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  • 1985-1989
  • 1975-1979  (466)
  • 1830-1839
  • 1978  (466)
  • Chemical Engineering  (394)
  • Rat
  • 1
    Electronic Resource
    Electronic Resource
    Myopathy associated with chronic alcohol drinking (1978)
    Springer
    Virchows Archiv 378 (1978), S. 45-53 
    Details
    ISSN: 1432-2307
    Keywords: Alcohol ; Myopathy ; Histochemistry ; Electrophysiology ; Human ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Muscles of the lower legs of rats given 25% ethanol in water ad libitum for up to 9.5 months were studied using histological, histochemical and electrophysiological techniques. Ethyl alcohol was substituted for about 20% of the total calorific input of the animals. The observations were compared with the structure of the gastrocnemius muscle of five alcoholics with clinical neuropathy. Fibrillation potentials and angulated atrophic fibers were observed in the muscles of animals on alcohol for 9.5 months. No fiber type grouping was present. There was also phagocytosis of the muscle fibers and changes in their internal structure, as reflected by the distribution of NADH-diaphorase. The observed muscle changes in the alcoholics and those in the experimental animals on alcohol differed mainly quantitatively, the only exception being the presence of fiber type grouping in the biopsies from the alcoholics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00427185
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  • 2
    Electronic Resource
    Electronic Resource
    Blood volume and body haematocrit of rats native to a simulated altitude of 3500 m (1978)
    Springer
    Pflügers Archiv 374 (1978), S. 285-288 
    Details
    ISSN: 1432-2013
    Keywords: High altitude ; Blood volume ; Red cell volume ; Plasma volume ; Body haematocrit ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Circulating blood volume (BV) as the sum of circulating red cell volume (RCV) and plasma volume (PV) was estimated in rats native to a simulated altitude of 3500 m (“natives”), in rats born at sea level and later in life transferred to the simulated high altitude (“newcomers”), and in control sea-level rats. RCV per kg body weight (b.w.) was significantly larger in both “newcomers” and “natives” than in controls. PV per kg b.w. was in the “newcomers” insignificantly and in the “natives” significantly smaller than in the controls. BV per kg b.w. in both high altitude groups tended to be larger than in controls but the difference was not significant. Arterial haematocrit (Ahct) in the “newcomers” was significantly higher than in the controls, and in the “natives” significantly higher than in both other groups. Body haematocrit (the ratio of RCV and BV in per cent) was smaller than Ahct in all groups; this was more pronounced in the “newcomers” than in the controls and even more so in the “natives”. Apparently the haematocrit in the minute vessels of the organs of animals exposed to chronic hypoxic hypoxia increases much less than might be expected from changes of the Ahct. An attempt was made to evaluate the possible error of the more commonly used method of estimating BV, when only RCV, or only PV, is measured, and BV and its complementary fraction are calculated from arterial or venous haematocrit. When, in our results, BV was calculated from RCV and Ahct, the absolute values and also the differences between groups were somewhat underestimated. When BV was calculated from PV and Ahct, the BV itself, and particularly the differences between groups, were overestimated quite considerably. It is suggested that the only safe way to estimate BV is to measure RCV and PV separately.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00585606
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  • 3
    Electronic Resource
    Electronic Resource
    Influence of polyphloretin phosphate on the central effects of prostaglandin E2 and F2α in rats (1978)
    Springer
    Psychopharmacology 59 (1978), S. 273-277 
    Details
    ISSN: 1432-2072
    Keywords: Polyphloretin phosphate ; Prostaglandins ; Behaviour ; Temperature ; Bram biogenic amines ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The possibility that polyphloretin phosphate (PPP) antagonizes the central effects elicited by prostaglandin (PG) E2 and F2α was investigated. PPP was administered i.c.v. to male Wistar rats (10 or 25 μg) 10 or 30 min before i.c.v. injection of PGE2 or PGF2α (1 or 10 μg). The duration of several components of behavior, the degree of irritability, and the rectal temperature of rats were measured; the levels of noradrenaline, dopamine, 5-hydroxytryptamine, and 5-hydroxyindoleacetic acid were measured spectrophotofluorometrically in discrete brain areas. PPP antagonized temperature and behavioral changes induced in rats by PGF2α, but not those induced by PGE2. The magnitude of antagonism depended on the dose of PPP and on the time of the pretreatment before PGF2α administration. Changes in the level of biogenic amines in discrete brain areas evoked by PGs were not affected by PPP. We found that PPP antagonizes the central effects of PGF2α but not those of PGE2, and that changes of biogenic amines in discrete brain areas elicited by PGs are not specific.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00426634
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  • 4
    Electronic Resource
    Electronic Resource
    Concentrative amino acid uptake at the serosal side of colon mucosa (1978)
    Springer
    Pflügers Archiv 376 (1978), S. 245-249 
    Details
    ISSN: 1432-2013
    Keywords: Colon ; Amino acid uptake ; Basolateral membrane ; Active transport ; Sheep ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Uptake of the nonmetabolizable model amino acid 2-aminoisobutyric acid (=AIB) through the basolateral membrane into epithelial cells was studied in sheep colon stripped of serosa and muscle layers. Only the antiluminal surface of the mucosa was exposed to the incubation medium. Thus AIB entry into epithelial cells could only occur through the basolateral membrane. AIB was taken up by a saturable process against a high concentration gradient. AIB uptake was inhibited by other neutral amino acids but not by sugars. In a low Na+ medium AIB uptake was impaired, indicating that active transport of amino acids through the basolateral membrane of colon epithelial cells is Na+-dependent. In the rat a saturable concentrative uptake of AIB through the basolateral membrane of colon epithelial cells has also been demonstrated. Concentrative uptake of amino acids through the basolateral membranes is probably important for the supply of colon epithelium with amino acids.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00584958
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  • 5
    Electronic Resource
    Electronic Resource
    Influence of glomerular filtration rate on renal PAH secretion rate in the rat kidney (1978)
    Springer
    Pflügers Archiv 375 (1978), S. 131-139 
    Details
    ISSN: 1432-2013
    Keywords: PAH clearance ; PAH extraction ; Glomerular filtration rate ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract PAH secretion (TPAH) was studied in rats at spontaneously occurring glomerular filtration rate (GFR). At saturated transport, TPAH was found to be correlated to GFR. This relationship was also observed at unsaturated transport where TPAH depends upon the PAH concentration in arterial plasma. However, no significant correlation between TPAH and renal PAH load or renal plasma flow rate was found when the effects of GFR were removed by partial correlation analysis. A dependency of TPAH on GFR explains the correlations found between filtration fraction (FF) and renal PAH extraction (EPAH) or renal tubular PAH extraction fraction (EPAH-FFPAH). Thus, even at low PAH concentration in a. plasma, renal PAH extraction may only be assumed to be constant if the filtration fraction is constant.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00584235
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  • 6
    Electronic Resource
    Electronic Resource
    Blood gases at several levels of oxygenation in rats with a left-shifted blood oxygen dissociation curve (1978)
    Springer
    Pflügers Archiv 376 (1978), S. 7-13 
    Details
    ISSN: 1432-2013
    Keywords: Oxygen dissociation curve ; Oxygen transport ; Blood gases ; Hypoxia ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Theoretical deductions have shown that a shift of the blood O2 dissociation curve (ODC) to the right might improve O2 transport to tissues at normoxia and at mild hypoxia whereas at severe hypoxia the organism should be better off with an ODC shifted to the left (Turek et al., 1973b; Turek and Kreuzer, 1976). The present study was performed in order to ascertain this ambiguous effect of an ODC shift depending on the degree of hypoxia in intact animals. A major displacement of the ODC to the left was achieved in rats by chronic administration of sodium cyanate (NaOCN). Control animals received sodium chloride (NaCl) instead. Arterial and mixed-venous $$P_{{\text{O}}_{\text{2}} }$$ , $$P_{{\text{CO}}_{\text{2}} }$$ , and pH were measured at normoxia and during breathing 14.9, 8.0, or 5.6% O2 in N2 in both groups. From $$P_{{\text{O}}_{\text{2}} }$$ , pH, ODC and arterial hematocrit, arterial and mixed-venous O2 contents were estimated and $$({\text{a}} - {\text{v)}}_{{\text{O}}_{\text{2}} }$$ as an index of blood O2 extraction was obtained. At normoxia and during breathing 14.9% O2 the NaOCN rats had a lower mixed-venous $$P_{{\text{O}}_{\text{2}} }$$ than the NaCl rats without any difference in pH. Arterio-venous O2 difference did not differ at normoxia but was lower in NaOCN rats at 14.9% O2. However, at 8.0 and 5.6% O2 the NaOCN rats had a higher mixed-venous $$P_{{\text{O}}_{\text{2}} }$$ , an increased $$({\text{a}} - {\text{v)}}_{{\text{O}}_{\text{2}} }$$ , and a higher pH (arterial and mixed-venous). At 5.6% O2 the NaCl rats developed a severe acidosis concomitant with pronounced hypocapnia. These findings confirm that rats with a left-shifted ODC have an impaired O2 transport to tissues at normoxia and mild hypoxia but a more efficient O2 transport at severe hypoxia as compared with rats with an unshifted ODC, in agreement with our previous theoretical studies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00585241
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  • 7
    Electronic Resource
    Electronic Resource
    Blood O2 content, cardiac output, and flow to organs at several levels of oxygenation in rats with a left-shifted blood oxygen dissociation curve (1978)
    Springer
    Pflügers Archiv 376 (1978), S. 201-207 
    Details
    ISSN: 1432-2013
    Keywords: Oxygen dissociation curve ; Oxygen transport ; Cardiac output ; Coronary blood flow ; Blood flow to organs ; Hypoxia ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A major displacement of the blood O2 dissociation curve (ODC) was achieved in rats by chronic administration of sodium cyanate (NaOCN). Control animals with a normal position of the ODC received NaCl instead. Arterial and mixed-venous O2 content ( $${\text{C}}_{{\text{O}}_{\text{2}} }$$ ) and O2 consumption were measured during breathing room air, 14.9, 8.0, or 5.6% O2 in N2. Cardiac output was obtained by the Fick principle.86RbCl was administered i.v., the rats were killed and the activity of86Rb in heart, spleen, stomach and intestines, liver, kidney, skeletal muscle, and skin was measured. According to Sapirstein (1956, 1958) the fractional uptake of86Rb in these organs corresponds to the fractions of cardiac output supplying these organs, and from the fractional uptake and cardiac output the nutritional blood flow may be calculated. Arterial and mixed-venous $${\text{C}}_{{\text{O}}_{\text{2}} }$$ was larger in the NaOCN than in the NaCl rats at all levels of oxygenation. At normoxia and 14.9% O2 the venous $${\text{C}}_{{\text{O}}_{\text{2}} }$$ was enlarged more than the arterial one, and so the arterio-venous O2 difference [ $$\left( {{\text{a}} - {\text{v}}} \right)_{{\text{O}}_{\text{2}} }$$ ] as an index of the O2 extraction in the body was smaller in the rats with a left-shifted ODC. However, at more severe hypoxia (8.0 and 5.6% O2) the arterial $${\text{C}}_{{\text{O}}_{\text{2}} }$$ in the NaOCN rats was enlarged more than the mixed-venous one, resulting in a larger $$\left( {{\text{a}} - {\text{v}}} \right)_{{\text{O}}_{\text{2}} }$$ (and therefore O2 extraction) when compared with the NaCl animals. Cardiac output was larger in the NaOCN than in the NaCl rats at 14.9 and 5.6% O2, when expressed per kg body weight. At 14.9% O2 the augmented cardiac output compensated for the lower O2 extraction when compared with the NaCl animals. At 5.6% O2 the NaOCN rats had both a larger ( $$\left( {{\text{a}} - {\text{v}}} \right)_{{\text{O}}_{\text{2}} }$$ ) and cardiac output than the NaCl animals. In the NaCl rats the decreased O2 extraction was not compensated for by an augmented cardiac output and therefore their O2 consumption was not only lower than that of the NaOCN rats but decreased even below the normoxic value of the NaCl rats. Coronary blood flow was increased in both NaOCN and NaCl animals at deep hypoxia to about the same extent, but due to a much lower arterial $${\text{C}}_{{\text{O}}_{\text{2}} }$$ of the NaCl animals, their O2 supply to the heart was lower than that of the NaOCN rats. The nutritional blood flow to spleen, kidney, liver, stomach and intestines, and skin in ml/min · g was lower in the rats with a normal position of the ODC than in those with a left-shifted ODC. This, together with the low arterial $${\text{C}}_{{\text{O}}_{\text{2}} }$$ of the NaCl rats, suggests a serious compromising of the O2 supply to these organs. Results of this study support the conclusion of our theoretical studies (Turek et al., 1973; Turek and Kreuzer, 1976) that a shift of the ODC to the left might be disadvantageous for the O2 transport to tissues at mild hypoxia, but advantageous at severe hypoxia.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00584951
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  • 8
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    Electronic Resource
    Arterial blood gases, muscle fiber diameter and intercapillary distance in cardiac hypertrophy of rats with an old myocardial infarction (1978)
    Springer
    Pflügers Archiv 376 (1978), S. 209-215 
    Details
    ISSN: 1432-2013
    Keywords: Blood gases ; Cardiac hypertrophy ; Intercapillary distance ; Myocardial infarction ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In rats with a myocardial infarction due to ligation of the left coronary artery a marked right ventricular hypertrophy developed after 41/2 weeks. At this time no difference against control animals was observed in arterial $$P_{{\text{O}}_2 }$$ , $$P_{{\text{CO}}_2 }$$ , pH, ideal alveolar $$P_{{\text{O}}_2 }$$ , and alveolar-arterial O2 pressure difference, as measured in unanesthetized animals at normoxia. In histological sections of the heart stained by PAS reaction capillaries and muscle fibers were counted, and the mean intercapillary distance and muscle fiber diameter were estimated. In the right ventricle of the rats with myocardial infarction both increased when compared with control animals or with sham-operated rats. Fibercapillary ratio was the same in all three groups. Similar results were obtained in the remaining undamaged tissue of the left ventricle of rats with a myocardial infarction when compared with the left ventricle of control or sham-operated rats. Findings concerning intercapillary distance suggest that also in the myocardium which remains intact during the development of the infarction and later hypertrophies, tissue oxygen transport might be impaired, particularly during a stress situation. Results in the right ventricle of rats with myocardial infarction show an opposite trend against rats exposed chronically to simulated high altitude, where in the hypertrophied right ventricle a shorter intercapillary distance occurs and therefore an improvement of tissue oxygen transport might be expected.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00584952
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  • 9
    Electronic Resource
    Electronic Resource
    Effect of the phosphodiesterase inhibitor 4-(3-cyclopentyloxy-4-methoxyphenyl)-2-pyrrolidone (ZK 62711) on gastric secretion and gastric mucosal cyclic AMP (1978)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 304 (1978), S. 69-75 
    Details
    ISSN: 1432-1912
    Keywords: Gastric secretion ; Cyclic AMP ; Phosphodiesterase inhibitor ; Rat ; Guinea pig
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The effect of the phosphodiesterase inhibitor 4-(3-cyclopentyloxy-4-methoxyphenyl)-2-pyrrolidone (ZK 62711) on gastric secretion and the cyclic AMP system of the gastric mucosa was studied in rats and guinea pigs. In rats, 0.03–0.3 μmoles/kg ZK 62711 i.v. stimulated acid and pepsin secretion in a dose-dependent manner and 0.03 μmoles/kg i.v. enhanced the effect of histamine. In guinea pigs no reproducible stimulation was found after intravenous injections of ZK 62711. The stimulation of gastric secretion in the rat by 0.3 μmoles/kg ZK 62711 i.v. was not affected by vagotomy but was totally inhibited by 10 μmoles/kg cimetidine i.v. The structurally related phosphodiesterase inhibitor, 4-(3-butoxy-4-methoxybenzyl)-2-imidazolidine (Ro 20-1724), at the dose of 3.3 μmoles/kg i.v. stimulated gastric secretion in anaesthetised rats to a similar extent as 0.3 μmoles/kg ZK 62711 i.v. The content of cyclic AMP in the rat gastric mucosa in vivo was slightly increased by 10 μmoles/kg ZK 62711 i.v, whereas lower doses did not change it. Accumulation of cyclic AMP in the rat gastric mucosa by 50 μmoles/kg histamine i.v. was enhanced by simultaneous injections of 3.3 μmoles/kg ZK 62711 i.v. In rat gastric tissue slices in vitro 1–50 μM ZK 62711 increased the level of cyclic AMP but 100 μM histamine had no effect in the absence or presence of ZK 62711. In gastric mucosal slices of the guinea pig 10 and 50 μM ZK 62711 increased the cyclic AMP content which effect was inhibited by 100 μM cimetidine and enhanced the stimulatory effect of 100 μM histamine on cyclic AMP. The activity of soluble cyclic AMP phosphodiesterase was inhibited by ZK 62711 in the rat (IC50=18 μM) and guinea pig gastric mucosa (IC50=1.5 μM). Adenylate cyclase was not affected in the homogenate of the guinea pig gastric mucosa. The results indicate that the phosphodiesterase inhibitor ZK 62711 which increases cyclic AMP levels in the gastric mucosa in vivo and in vitro, is a potent stimulator of gastric acid secretion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00501379
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  • 10
    Electronic Resource
    Electronic Resource
    On the presence and distribution of α-adrenoceptors in the heart of various mammalian species (1978)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 302 (1978), S. 239-254 
    Details
    ISSN: 1432-1912
    Keywords: Myocardial α-adrenoceptors ; Rat ; Guinea pig ; Cat ; Hypothyroidism ; Single adrenoceptor type
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The presence and distribution of myocardial α-adrenoceptors in different parts of the heart of various mammalian species was investigated. For this reason experiments were performed in isolated cardiac preparations of rats, guinea pigs and cats. In order to obtain more information about the nature of the cardiac α-adrenoceptors additional experiments were undertaken at different temperatures. These studies were aimed to show whether or not a conversion of β-to α-adrenoceptors or vice versa takes place. Moreover, we analyzed the influence of hypothyroidism on the sensitivity of α- and β-adrenoceptors of preparations from rats fed with propylthiouracil. Finally, we tried to find out whether stimulation of these α-adrenoceptors leads to the formation of the cyclic nucleotides cAMP and cGMP. The following results were obtained: 1. In right ventricular strips of rats, guinea pigs and cats phenylephrine stimulated α-adrenoceptors. After blockade of β-adrenoceptors the respective pD2-values of phenylephrine were 5.32, 5.99 and 5.33. The doseresponse curves obtained in the presence of α-adrenolytic drugs were shifted to the right without depression of the maximum. In the rat, in addition, the pA2-values for the α-adrenolytic drugs yohimbine (5.79) and phentolamine (7.85) were determined. They were at least 0.5 log units higher than those found in the rat for other α-adrenoceptors (Van Rossum, 1965) thus supporting the view that the population of cardiac α-adrenoceptors is different from that of other organs. In left ventricular strips of guinea pigs the pD2-value for the α-mimetic effect of phenylephrine was of the same order of magnitude as that obtained in the right ventricle. 2. In the papillary muscle of the right ventricle of guinea pigs and cats phenylephrine stimulated α-adrenoceptors. 3. In the left atrium of the rat, phenylephrine stimulated myocardial α-adrenoceptors (pD2: 5.58). Also in this preparation the pA2-values for yohimbine (6.36) and phentolamine (8.21) were different from those found for other α-adrenoceptors in the rat (Van Rossum, 1965). Likewise in strips from the left atrium of the cat myocardial α-adrenoceptors are present. 4. In spontaneously beating right atria of the rat a clear-cut positive chronotropic effect mediated by stimulation of α-adrenoceptors could not be demonstrated although in 6 out of 15 preparations a small positive chronotropic effect became evident. No positive chronotropic effect at all was obtained by stimulation of α-adrenoceptors in the cat right atrium. 5. In ventricular strips as well as in left atria from hypothyroid rats the pD2-value for the α-effect of phenylephrine was increased, in the atrium more than in the ventricle, while the pA2-values for yohimbine and phentolamine were not significantly different from the controls. Under these conditions a distinct positive chronotropic effect mediated by stimulation of α-receptors was found in the spontaneously beating rat atrium. 6. After stimulation of α-adrenoceptors in atria and ventricular strips of normal and propylthiouraciltreated rats, as well as in strips of guinea-pig ventricles or cat atria no elevation of cAMP and cGMP was observed. 7. The concept of a single adrenoceptor convertible from α- to β-type or vice versa was not supported by our experiments. These were carried out at different temperatures on left atria and on ventricular strips of rat hearts using the irreversible α-adrenoceptor blocking agent phenoxybenzamine. 8. The present experiments provide evidence for the existence of α-adrenoceptors in the myocardium of various mammalian species. Their stimulation produces positive inotropic effects without increases in heart rate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00508293
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  • 11
    Electronic Resource
    Electronic Resource
    Diurnal variations in the motor activity of the rat: Effects of inhibitors of the catecholamine synthesis (1978)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 303 (1978), S. 251-256 
    Details
    ISSN: 1432-1912
    Keywords: Diurnal rhythm ; Motor activity ; Rat ; H 44/68 ; FLA 63 ; Animex
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The effects of the inhibitor of the tyrosine-hydroxylase H 44/68 and the inhibitor of the dopamine-β-hydroxylase FLA 63 on the diurnal variations of the motor activity was studied in male Wistar rats, which were kept under standardized conditions of light and darkness (L:D=12:12h). The motor activity was continuously registered in groups of 5 rats using a two-channel Animex motimeter. During light FLA 63 (40 mg/kg, s.c.) greatly increased motor activity on acute application and during darkness the physiological elevation in motor activity was further but slightly increased. H 44/68 (200 mg/kg, i.p.) also increased motor activity during light, but in contrast to FLA 63 greatly reduced motor activity during darkness. The results indicate that though dopamine and noradrenaline are involved in the regulation of behavioural components, one or the other catecholamine may play a predominant role at different times of the day. Thus, it seems worthwhile to study the effects of drugs separately during light and during darkness.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00498051
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  • 12
    Electronic Resource
    Electronic Resource
    The effect of some neuroleptics on the interaction of cortically and nigrally evoked potentials in the rat striatum (1978)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 303 (1978), S. 165-170 
    Details
    ISSN: 1432-1912
    Keywords: Striatum ; Evoked potentials ; Neuroleptics ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The interaction of cortico- and nigrofugal inputs to the striatum of the rat was investigated using the technique of evoked potentials. Repetitive, unilateral stimulation of the substantia nigra inhibited potentials which were evoked from the ipsilateral rostral cortex and recorded from the ipsilateral striatum. The inhibition was antagonized by low doses of various intraperitoneally administered neuroleptics such as: pimozide (0.1–0.2 mg/kg), haloperidol (0.1–0.5 mg/kg), chlorpromazine (0.5–2.0 mg/kg) and thioridazine azine (0.5–4.0 mg/kg). These findings are discussed in view of the existing controversy regarding the mode of action of dopamine in the striatum.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00508063
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  • 13
    Electronic Resource
    Electronic Resource
    Diurnal rhythm in the central dopamine turnover in the rat (1978)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 303 (1978), S. 257-261 
    Details
    ISSN: 1432-1912
    Keywords: Diurnal rhythm ; Central noradrenaline and dopamine turnover ; H 44/68 ; FLA 63 ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Under controlled conditions of environmental light and darkness of 12:12 h the turnover of dopamine and noradrenaline in brain of male Wistar rats was studied at different times of the day. The turnover was calculated from the decline of the amine concentrations either after inhibition of the tyrosine-hydroxylase with H 44/68 (200 mg/kg, i.p.) or after inhibition of the dopamine-β-hydroxylase with FLA 63 (40 mg/kg s.c.). Whereas the noradrenaline turnover showed only slight but not significant variations within 24 h, the turnover of the central dopamine exhibited significant variations with increased turnover rates in the second half of the light and first half of the dark period. Thus, diurnal variations have to be taken into account when studying the effects of drugs on the turnover of biogenic amines in the central nervous system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00498052
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  • 14
    Electronic Resource
    Electronic Resource
    Perhexiline induces generalized lipidosis in rats (1978)
    Springer
    Journal of molecular medicine 56 (1978), S. 309-310 
    Details
    ISSN: 1432-1440
    Keywords: Perhexilin-Maleat ; generalisierte Lipidose ; Ratte ; Perhexiline maleate ; Generalized lipidosis ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary Administration of perhexiline (Pexide®) to rats causes generalized occurrence of lamellated and crystalloid cytoplasmic inclusions which resemble those described in patients with perhexiline-induced polyneuropathy. It is concluded that perhexiline being an amphiphilic cationic compound is a potent inducer of generalized lipidosis.
    Notes: Zusammenfassung Perhexilin (Pexid®) verursacht bei der Ratte das generalisierte Auftreten von lamellären und kristalloiden zytoplasmatischen Einschlußkörpern, die denjenigen gleichen, die bei Patienten mit Perhexilin-induzierter Polyneuropathie beschrieben worden sind. Aus den vorgelegten Befunden wird geschlossen, daß Perhexilin, eine amphiphile kationische Verbindung, ein starker Induktor einer generalisierten Lipidose ist.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01489178
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  • 15
    Electronic Resource
    Electronic Resource
    In vivo DNA repair after N-methyl-N-nitrosourea administration to rats of different ages (1978)
    Springer
    Journal of cancer research and clinical oncology 91 (1978), S. 157-164 
    Details
    ISSN: 1432-1335
    Keywords: MNU ; DNA Repair ; Rat ; Age
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary DNA repair time-course was studied after injury by N-methyl-N-nitrosourea (MNU) in rat liver cells of animals of different ages and in fetuses using hydroxyurea (HU) as inhibitor of scheduled DNA synthesis. DNA repair was a rapid phenomenon, more so in young adults than in newborns, and was not detectable in fetuses. A correlation seems to exist among organ sensitivity to carcinogen, age of animal and DNA repair.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00284022
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  • 16
    Electronic Resource
    Electronic Resource
    Scanning electron microscopical study on the fluorosis of enamel in rats (1978)
    Springer
    Calcified tissue international 25 (1978), S. 75-83 
    Details
    ISSN: 1432-0827
    Keywords: Rat ; Fluorosis ; Enamel ; Scanning electron microscopy ; Low temperature incineration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Sixteen 58-day-old male rats of Wistar strain, with a mean body weight of 179 g, were divided into two equal groups. Each group of eight animals was maintained for 70 days on drinking water, ad lib., containing no fluorine (control group) and 100 ppm of fluorine (experimental group). All specimens examined were obtained from the incisal portions of the incisors. The following types of enamel specimens were prepared for scanning electron microscopy: (1) acid-etched specimens; (2) acid-etched specimens followed by low temperature microincineration; and (3) fractured specimens. The enamel formed during high fluoride exposure showed marked hypocalcification, that is, the crystallite density in the prism core and interprismatic region was lower than that of control animals. The organic substances appeared to increase in these regions. These changes were prominent in the outer and middle enamel layers. Such changes following fluoride administration appear to indicate an inhibition of enamel maturation, that is, an inhibition of the mineral deposition and/or an inhibition of organic matrix withdrawal.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02010754
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  • 17
    Electronic Resource
    Electronic Resource
    Scanning electron microscopic studies of ileal epithelial cells in suckling rats (1978)
    Springer
    Anatomy and embryology 153 (1978), S. 1-8 
    Details
    ISSN: 1432-0568
    Keywords: Ileal epithelial cell ; Suckling period ; Rat ; Scanning electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The ileal epithelial cells containing the tubulo-vacuolar systems and supranuclear vacuoles in suckling rats were investigated with scanning electron microscopy, using specimens treated with osmium-thiocarbohydrazide-osmium staining methods, and critical point drying and cracking. The cracked surface of the apical cytoplasm is seen as irregular and small hollows and pores of the anastomosing and branching tubulo-vacuolar system. The cracked surface of the supranuclear vacuoles shows the ellipsoidal structures. Numerous pores of various size and irregular shape are present on the apical inner surface of the supranuclear vacuole. These pores are clearly the openings from the tubulo-vacuolar system to the supranuclear vacuole. Some small pores are visible on the inner lateral surface of the supranuclear vacuole, especially near the nucleus. They are probably the pathways of the absorbed materials from the supranuclear vacuole into the lateral cytoplasm. Usually, the inclusions of the supranuclear vacuole reveal the globes or coarse and sponge-like networks.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00569845
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  • 18
    Electronic Resource
    Electronic Resource
    Der Sauerstoffverbrauch des spontanen und künstlich induzierten Hautcyclus zu verschiedenen Tageszeiten (1978)
    Springer
    Archives of dermatological research 262 (1978), S. 167-172 
    Details
    ISSN: 1432-069X
    Keywords: Rat ; Oxygen uptake ; Induced skincycle ; Spontaneous skincycle ; Diurnal rhythm ; Ratte ; Sauerstoffverbrauch ; Induzierter Hautcyclus ; Spontaner Hautcyclus ; Tagesschwankung
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung In der vom Panniculus carnosus gereinigten “glatten” Rattenhaut wurde der Sauerstoffverbrauch des spontanen und induzierten Hautcyclus zu verschiedenen Tageszeiten ermittelt. Das Niveau des Sauerstoffverbrauches korrelierte mit den Tag-Nacht-Zeiten. Der Sauerstoffverbrauch zeigte während des Hautcyclus Schwankungen. Ferner fanden sich Anhaltspunkte, daß der frühanagene Wert des Sauerstoffverbrauches von der Cyclusphase mit beeinflußt wird, während welcher der neue Cyclus künstlich induziert wird. Weiter wurde festgestellt, daß eine gewisse Abnahme des Sauerstoffverbrauches die ruhenden Haarfollikel zur spontanen Proliferation anregt. Während des Katagen schien der Maximalwert des Sauerstoffverbrauches mit speziellen morphofunktionellen perifollikulären Veränderungen in Beziehung zu stehen. Die Übertragung dieser Befunde auf die Pathophysiologie menschlicher Haarwachstumsstörungen wird erwogen.
    Notes: Summary In the “clean” rat skin purified from the panniculus carnosus the oxygen consumption of the spontaneous and artificially induced skincycle was measured at different times of day. The level of oxygen consumption correlated to diurnal and nocturnal periods. During the skincycle the oxygen consumption showed fluctuations. There were indications that the value of oxygen consumption of the early anagen is influenced by that phase of the cycle at which the new cycle is artificially induced. Furthermore, it was found that a certain decrease of oxygen consumption stimulates the quiescent hair follicles to spontaneous proliferation. During the katagen the peak value of the oxygen consumption seemed to be correlated with specially morphofunctional perifollicular changes. The application of these findings to the pathophysiology of human hair growth disturbances is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00455386
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  • 19
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    Electronic Resource
    Normal and 6-aminonicotinamide impaired development of capillarization in occipital cortex of rat (1978)
    Springer
    Anatomy and embryology 154 (1978), S. 27-37 
    Details
    ISSN: 1432-0568
    Keywords: Capillarization ; Cortex ; Rat ; 6-Aminonicotinamide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary During different embryonic and postnatal stages, 6-aminonicotinamide (6-AN) was administered to Wistar albino rats. The capillarization of the occipital cortex has been examined morphometrically. A 6-AN-vulnerable stage of prenatal development was found, which lasted to the 19th prenatal day and which only partly corresponds to the so-called ‘critical stage’ of capillary sprouting (Kapillarsprossung). Capillary sprouting was not impaired by 6-AN during postnatal stages. Impairment of capillarization by 6-AN might be the result of glial lesion. The importance of glia for capillarization is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00317952
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  • 20
    Electronic Resource
    Electronic Resource
    Pre- and postnatal development of catecholamine-containing and cholinesterase-positive nerves of the rat cornea and iris (1978)
    Springer
    Anatomy and embryology 154 (1978), S. 253-265 
    Details
    ISSN: 1432-0568
    Keywords: Rat ; Iris ; Cornea ; Catecholamine fluorescence ; Cholinesterase ; Histochemistry ; Ontogenesis ; Catecholamines
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Glyoxylic acid-induced fluorescence technique and a copper thiocholine method were used to investigate the ontogenesis of the catecholamine-containing and cholinesterase-positive nerves of the rat iris and cornea. First fluorescent nerve fibres appeared in the iris on the 18th gestation day and in the cornea on the 19th day. A rapid increase in the density of the adrenergic nerve fibres of the iris continued to the age of three weeks, while the number of such fibres were small in the cornea. Acetylcholinesterase-positive fibres appeared both in the cornea and in the iris on the 19th gestation day. Their density increased more rapidly in the iris, especially in the sphincter muscle, than in the cornea. Non-specific cholinesterase activity was localized in the Schwann cells and the reaction was more intense during development than in the nerves of the cornea of adult rats.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00345656
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  • 21
    Electronic Resource
    Electronic Resource
    Developmental organization of raphe serotonin neuron groups in the rat (1978)
    Springer
    Anatomy and embryology 154 (1978), S. 241-251 
    Details
    ISSN: 1432-0568
    Keywords: Nervous system ; Serotonin ; Raphe nuclei ; Development ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The pre- and early postnatal development of serotonin neurons in the rat brainstem was studied using the fluorescence histochemical method. The technique utilized does not require drug pretreatment to visualize an intense serotonin fluorophore localized in neuronal perikarya, dendrites, and axons. All the serotonin neuron groups develop as bilateral nuclei which extend from the midbrain through the medulla. Six of the nine groups undergo a midline fusion from embryonic day 18 (E 18) through postnatal day 6 (P 6) in a rostrocaudal gradient. Cells of the nucleus raphe dorsalis fuse first (by P1), whereas the serotonin neurons located in nucleus raphe pallidus do not fuse until P 6. This gradient is comparable to the one described for the first observable fluorescence in the serotonin neurons groups. After final cell division, the serotonin neurons undergo a primary migration from the ventricular zone along the midline, where they are situated during embryogenesis, and a secondary migration extending into postnatal life which concludes with fusion in the midline. The bilateral origins of the serotonin cell groups are maintained in the adult. This is expressed by the apparent ipsilateral projections of some of the raphe neurons determined recently in our laboratory utilizing autoradiographic and horseradish peroxidase techniques.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00345655
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  • 22
    Electronic Resource
    Electronic Resource
    Morphological changes in CNS of rats treated with perhexiline maleate (Pexid) (1978)
    Springer
    Acta neuropathologica 42 (1978), S. 159-164 
    Details
    ISSN: 1432-0533
    Keywords: Perhexiline maleate ; Pexid ; Abnormal inclusion ; Rat ; CNS
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The basic cellular lesion in CNS of suckling rats treated with Pexid was studied by light and electron microscopy. The most pronounced abnormality, the formation of various intracytoplasmic inclusions, was found in neurons, astrocytes, oligodendrocytes, ependymal cells, endothelial cells and fibroblasts. These abnormal inclusions were generally membrane-bound, although clearly non-membrane-bound inclusions were occasionally found. The several internal patterns of the inclusions were (1) lamellar, both concentric and parallel, (2) reticular and (3) crystalloid. These alterations were completely resersed following withdrawal of the drug. The structural characteristics of the abnormal inclusions in Pexid-treated animals were similar to those found with certain hypocholesterolemic, neuroleptic, anorectic, and antimalarial drugs. This suggests that the inclusions occurring within the cells of animals treated with any of these drugs may develop in a similar manner, and that the formation of such inclusions is likely to be a form of cellular reaction common to certain metabolic disturbances.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00690352
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  • 23
    Electronic Resource
    Electronic Resource
    Schwann cells and peripheral nervous system myelin in the rat retina (1978)
    Springer
    Acta neuropathologica 44 (1978), S. 245-247 
    Details
    ISSN: 1432-0533
    Keywords: Schwann cells ; PNS myelin ; Retina ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Within the retinal nerve fiber layer of a 6-week-old Sprague-Dawley rat, scattered aggregates of PNS myelinated axons have been found and described. We believe this is likely to represent a normal but rare phenomenon in the rat.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00691075
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  • 24
    Electronic Resource
    Electronic Resource
    Studies of rat alkaline phosphatase (1978)
    Springer
    Archives of toxicology 39 (1978), S. 249-266 
    Details
    ISSN: 1432-0738
    Keywords: Rat ; Alkaline phosphatase ; Plasma ; Organs ; Toxicity testing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A manual system of various estimations of rat plasma alkaline phosphatase activity has been devised for small volumes of plasma which uses different inhibitors, compares the utilisation of two substrates and includes acrylamide gel electrophoresis. The different inhibitors etc. allow a degree of discrimination between alkaline phosphatase extracts of rat organs. The properties of isoenzymes, e.g. intestinal alkaline phosphatase, differ depending upon the environment in which they are studied. In conjunction, if necessary, with the methods described for the estimation of liver and intestinal alkaline phosphatase activity, it is hoped to use the system to discriminate between the isoenzymes present in the plasma alkaline phosphatase of rats in toxicological studies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00296386
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  • 25
    Electronic Resource
    Electronic Resource
    Distention ulcer as a model for testing of drugs for ulcerogenic side effects (1978)
    Springer
    Archives of toxicology 41 (1978), S. 99-105 
    Details
    ISSN: 1432-0738
    Keywords: Rat ; Method ; Gastric ulceration ; Distention of stomach ; Stress ; Anti-inflammatory drugs ; Ulcerogenic side effect
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Das sog. „distention“-Ulkus wurde an Albinoratten untersucht und als neue Möglichkeit für die Feststellung ulzerogener Nebenwirkungen von Substanzen beschrieben. Die Dehnung des Magens in sich war nicht ausreichend um ulzerogene Läsionen auszulösen, denn die Dehnung des Magens mit physiologischer Kochsalzlösung führte nicht zur Ulzeration. Die Säure ist ein entscheidender Faktor in der Bildung des „distention“-Ulkus. Große Volumina von 0,1 N Salzsäure riefen innerhalb von 1 Std massive Ulzeration hervor. Kleine Mengen von dieser Säurelösung verursachten keine Ulzeration im Magen. Entzündungshemmer, die in noch von ulzerogenen Nebenwirkungen freien therapeutischen Dosen verabreicht wurden, erhöhten die Empfindlichkeit der gastralen Mukosa dem aggressiven Faktor, der Säure, gegenüber. Bei den mit bekanntlich ulzerogen wirkenden Dosen von Entzündungshemmern vorbehandelten Ratten wurde eine schnellere Bildung von Ulzera durch die Dehnung des Magens mit Säure beobachtet. Auch die Stressvorbehandlung beschleunigte und verstärkte die Bildung der durch Dehnung hervorgerufenen ulzerogenen Veränderungen im Magen.
    Notes: Abstract A modification of the distention ulcer was studied in albino rats and a new possibility of testing ulcerogenic side effects of drugs was described. The distention alone was not sufficient to produce lesions. The severity of ulcer lesions was highly dependent on the volume of the acid solution. Large volumes of 0.1 N HCl evoked severe ulcers within 1 h. Small amounts of weak acid solution did not cause any ulceration. Anti-inflammatory drugs administered in therapeutic doses, which did not yet produce any ulcers in animals, increased the sensitivity of the gastric mucosa against the aggresive factor, the acid. In animals pretreated by anti-inflammatory drugs in toxic doses an earlier development of ulceration was observed by distention with acid. Stress also accelerated and aggravated the formation of distention ulcers.
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    URL: http://dx.doi.org/10.1007/BF00351774
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  • 26
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    Electronic Resource
    Effect of acute and chronic cadmium treatment on hepatic drug metabolism in male rats (1978)
    Springer
    Archives of toxicology 40 (1978), S. 269-277 
    Details
    ISSN: 1432-0738
    Keywords: Cadmium ; Drug Metabolism ; Metallothionein ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The effect of acute and chronic cadmium administration on hepatic drug metabolism was investigated in the male rat. 3 days after the acute administration of cadmium by either the intraperitoneal (0.84 mg Cd/kg) or the oral (〉 80 mg Cd/kg) route, there was a significant potentiation in duration of hexobarbital hypnosis and inhibition of hepatic microsomal metabolism of hexobarbital and aniline. Administration of cadmium in the drinking water at levels of 100 or 200 ppm Cd for periods of 2–12 weeks or at levels of 5 or 20 ppm Cd for 50 weeks did not produce alterations in either drug response or hepatic drug metabolism. Significant levels of metallothionein, a cadmium binding protein, found in the liver of the rats receiving cadmium chronically may offer an explanation for the observed differences in drug metabolism between the acute and chronic administration of cadmium. In additional studies, pretreatment of the rats with subthreshold doses of cadmium (0.21 or 0.42 mg Cd/kg) intraperitoneally produced a tolerance to the alterations in drug metabolism induced by the previous cadmium dose (0.84 mg Cd/kg, i.p.). However, chronic cadmium treatment (5 or 20 ppm Cd for 50 weeks) did not impart any such tolerance to subsequently administered Cd (0.84 mg/kg) by the intraperitoneal route. The hepatic levels of metallothionein induced by the chronic cadmium treatment were only 30–60% of those induced by the subthreshold cadmium and thus may not have bound enough of the large challenge cadmium dose to produce the tolerance phenomenon.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00310332
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  • 27
    Electronic Resource
    Electronic Resource
    Studies of rat alkaline phosphatase (1978)
    Springer
    Archives of toxicology 39 (1978), S. 267-287 
    Details
    ISSN: 1432-0738
    Keywords: Rat ; Plasma ; Alkaline phosphatase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract This report describes the application of a test system which applies different substrates, inhibitors and acrylamide electrophoresis to the study of the alkaline phosphatase activity of rats. The system, which was specifically devised to characterise the alkaline phosphatase activity of small quantities of plasma from rats in toxicological studies, was also used to examine the plasma from rats under several physiological conditions, e.g. time of day, age, diet, etc. These physiological factors can influence the measurement of plasma alkaline phosphatase activity and should be taken into account when designing toxicological studies. Different experimental regimes were used to produce increases in liver, bone and intestinal alkaline phosphatase isoenzymes in the plasma of rats and these were reflected in the characterisations by the system. Although much remains unknown, a few concepts of rat plasma alkaline phosphatase activity emerged under our conditions. There is a ‘tidal’ intestinal component which arises from feeding and is approximately 60% of the total activity of the fed rat. In the fasted rat this ‘tidal’ component has largely disappeared and the ‘core’ activity which remains is composed of approximately equal proportions of bone isoenzyme and another as yet ill-defined component. The liver isoenzyme which appears in the plasma of the cholestatic rat appears to be either a very minor component or absent from the plasma of our normal CFE derived rat.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00296387
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  • 28
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    Electronic Resource
    Accelerated elimination of thallium in the rat due to subchronic treatment with furosemide (1978)
    Springer
    Archives of toxicology 40 (1978), S. 7-16 
    Details
    ISSN: 1432-0738
    Keywords: Thallium ; Furosemide ; Acetazolamide ; Renal elimination ; Oral absorption ; 204Tl ; Kidney ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Im Rahmen einer Untersuchung über das Schicksal von Thallium im Organismus und über den Einfluß von Diuretika auf die Eliminationsgeschwindigkeit dieses Giftes wurde Tl2SO4 (48.9 μmol = 10 mg/kg) an wachen Ratten oral verabreicht. Die Blutspiegel von Tl+ wurden anschließend als Funktion der Zeit ermittelt, sie konnten mit einer klassischen Bateman-Funktion nicht richtig beschrieben werden. Etwa l Std nach oraler Verabreichung war die Blutkonzentration maximal. Die Behandlung mit Furosemid (30 mg/kg) beschleunigte die Entfernung von Thallium aus dem Organismus auf signifikante Weise. Etwa 35% der zugeführten Menge Thallium wurde während einer Woche nach der Injektion dieses Diuretikums mit dem Urin ausgeschieden. Auch die Ausscheidung von Natriumionen und Wasser war signifikant erhöht, die von Kaliumionen blieb jedoch fast unverändert. Thallium selbst verursachte eine schwache diuretische Wirkung. Nach fortgesetzter Behandlung mit Furosemid (bis 2 Wochen) blieb die Eliminationsgeschwindigkeit von Thallium, Wasser und Natrium beschleunigt, während die Ausscheidung von Kaliumionen im Vergleich zu Kontrolltieren etwas herabgesetzt war. Ethacrynsäure verursachte nach wiederholter Gabe in diuretisch wirksamen Dosen eine retroperitoneale Fibrose. Dieses wirksame Diuretikum konnte daher nicht in die Untersuchung einbezogen werden. Acetazolamid (30 mg/kg) erhöhte ebenfalls die Ausscheidung von Thallium, vor allem innerhalb der anfänglichen 24 Std. Die Wirkung war weniger intensiv als die von Furosemid, sie war außerdem bald erschöpft. Die Ergebnisse legen den Schluß nahe, Furosemid in hohen Dosen sei eine wirksame Maßnahme zur Beschleunigung der Thalliumentfernung aus dem Organismus, zumindest im vorliegenden Tiermodell. Acetazolamid ist zu diesem Zwecke wahrscheinlich nicht geeignet.
    Notes: Abstract In connection with a programme of investigations concerning the disposition of thallium in the rat and the influence of diuretic agents on the rate of elimination of thallium from the body, Tl2SO4 (48.9 μmol = 10 mg/kg) was given by mouth to conscious rats. Blood levels were studied as a function of time. They could not be described adequately by means of a classical Bateman function. The maximum blood level was achieved approximately 1 h following oral ingestion. Treatment with furosemide for 11 days (30 mg/kg twice daily) significantly accelerated the removal of thallium from the body with the urine. Approximately 35% of the administered thallium was excreted within one week following the injection of this diuretic agent. The excretion of sodium and water was also considerably enhanced, that of potassium hardly changed. Thallium itself displayed weak diuretic activity. Upon prolonged treatment (1–2 weeks) with furosemide the elimination of thallium, water and Na+ was still accelerated, although that of potassium proved diminished with respect to controls. Ethacrynic acid when administered repeatedly in appropriate doses caused retroperitoneal fibrosis. Therefore, this potent diuretic agent was not included in the investigations. Acetazolamide (30 mg/kg) also enhanced the excretion of thallium, especially within the initial 24 h of treatment. The effect was less pronounced than that of furosemide and rapidly exhausted. The results suggest that furosemide in a high dose is effective in accelerating thallium elimination from the body in the present animal model. Acetazolamide is probably not suitable for this purpose.
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    URL: http://dx.doi.org/10.1007/BF00353275
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  • 29
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    Electronic Resource
    Tumor specific fluorescent and complement-dependent cytotoxic antibodies in the serum of rats with chemically induced brain gliomas (1978)
    Springer
    Acta neuropathologica 43 (1978), S. 111-117 
    Details
    ISSN: 1432-0533
    Keywords: Experimental brain gliomas ; Chemically induced ; Rat ; Cell cultures ; Humoral antibodies ; Immunofluorescence staining ; Microcytotoxicity assay
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Brain tumors were induced in Sprague-Dawley and Long-Evans rats by administration of N-methyl-N-nitrosourea in the drinking water. Of these tumors, a grade 2 mixed glioma, a grade 2 to 3 astrocytoma and a grade 1 to 2 oligodendroglioma were established in vitro, maintained in culture and designated 75SD-G-376, 75SD-G-420 and 77LE-G-180, respectively. Of these mass cultures, two were successfully cloned and are currently available as 75SD-G-376C and 75SD-420C cell lines. Clonal lines produce S-100 protein and grow as tumors when isografted in young rats. Using the cultured cells as target cells, specific antibodies were searched for in the sera of the rats with the primary tumors by means of an indirect fluorescent antibody staining method and a complement-dependent antibody-mediated microcytotoxicity assay. Fluorescent and cytotoxic antibodies were demonstrated in the sera of the mixed glioma- and astrocytoma-bearing animals. However, a variable proportion of cells of the 75SD-G-376 and 75SD-G-420 lines showed no reaction with the corresponding sera. Furthermore, cytotoxic anfibodies had a lytic effect on the autologous glioma cells only in the presence of rabbit complement.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00685005
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  • 30
    Electronic Resource
    Electronic Resource
    Cadmium induced endothelial cell alterations in the fetal brain from prenatal exposure (1978)
    Springer
    Acta neuropathologica 44 (1978), S. 147-149 
    Details
    ISSN: 1432-0533
    Keywords: Cadmium ; Endothelial cell ; Capillary ; Fetal brain ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Pregnant rats received a single administration of 0.5, 1.0, or 2.0 mg/kg of cadmium on day 18 or 20 or gestation Maternal animals were killed on day 21 and samples of the caudate nucleus from fetal brains were examined using the transmission electron microscope. A 2.0 mg/kg dose of cadmium administered to maternal rats on day 20 of gestation caused the formation of vacuoles in the endothelial cells of capilaries in the fetal brain. Significant endothelial cell vacuolization was not observed in the brain of fetuses from other treatment groups. The vacuoles occurred singly, were spherical in shape, were located adjacent to the intercellular junctions and caused focal distortion of the endothelial cell. Vacuoles were the only ultrastructural alteration observed in the caudate nucleus of fetal brains.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00691482
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  • 31
    Electronic Resource
    Electronic Resource
    Direct characterization ofΒ-adrenoceptors in membranes of immature red blood cells from rats (1978)
    Springer
    Annals of hematology 37 (1978), S. 295-306 
    Details
    ISSN: 1432-0584
    Keywords: Β-adrenerge Rezeptoren ; (3H) (−) Dihydroalprenolol ; Erythrozyten ; Ratte ; Β-Adrenoceptors ; (3H) (−) Dihydroalprenolol ; Erythrocytes ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary By means of the radioactive antagonist ligand (3H) (−) dihydroalprenolol (DHAP) specific binding sites were identified in membrane preparations from red blood cells from rats. These specific sites were characterized asΒ-adrenoceptors because of the following reasons: Specific binding of DHAP (in contrast to unspecific binding) was dependent on temparature and time of incubation. Furthermore, specific binding of DHAP showed saturability, temperature-dependent reversibility and high affinity (KD-value of DHAP = 6.51 nM). Specific binding of DHAP was competitively inhibited byΒ-adrenergic antagonists (pindolol 〉 alprenolol ≧ propranolol 〉 practolol) and agonists (isoprenaline 〉 adrenaline). The (−) enantiomers of pindolol and isoprenaline showed pronounced higher affinities for the receptor sites than the respective (+) enantiomers. The receptor density in the membrane preparations (pmoles/mg protein) was strongly dependent on the degree of reticulocytosis: The Bmax-values increased more than 4 to 5 fold without alteration of the respective KD-values when reticulocyte counts were enhanced from 3 to 80 % treatment of the animals with increasing doses of acetyl phenylhydrazine.
    Notes: Zusammenfassung Mittels des radioaktiv markierten Antagonist-Liganden (3H) (−) Dihydroalprenolol (DHAP) wurden spezifische Bindungsstellen in Membran-PrÄparationen von Erythrozyten der Ratte identifiziert, die aus folgenden Gründen alsΒ-adrenerge Rezeptoren angesprochen werden können: Im Gegensatz zur unspezifischen Bindung von DHAP war die spezifische Bindung abhÄngig von der Inkubationszeit und der Temperatur. Sie folgte einer SÄttigungskinetik, war — in AbhÄngigkeit von der Temperatur — reversibel und wies eine hohe AffinitÄt auf (KD für DHAP = 6,51 nM). Die rezeptorspezifische Bindung von DHAP wurde durchΒ-Rezeptorenblocker (Pindolol 〉 Alprenolol ≧ Propranolol 〉 Practolol) oderΒ-Sympathomimetika (Isoprenalin 〉 Adrenalin) kompetitiv gehemmt. Die (−) Enantiomeren von Pindolol und Isoprenalin hatten eine wesentlich höhere AffinitÄt als die antsprechenden (+) Enantiomeren. Die Dichte Β-adrenerger Rezeptoren (pmole/mg Eiwei\) nahm mit steigendem Retikulozytosegrad zu: Sie stieg auf das 4-bis 5fache an, wenn die Retikulozytenwerte durch Vorbehandlung der Tiere mit Azetylphenylhydrazin von 3 auf 80 % gesteigert wurden.
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    URL: http://dx.doi.org/10.1007/BF01007864
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    The influence of protein-calorie malnutrition on the development of internodal segments. A study on peripheral nerve and spinal roots in rats (1978)
    Springer
    Acta neuropathologica 41 (1978), S. 103-108 
    Details
    ISSN: 1432-0533
    Keywords: Protein-calorie malnutrition ; Rat ; Spinal root ; Sciatic nerve ; Internodal length
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The current investigation comprised normal young rats as well as rats submitted to a 50% food reduction or severe protein restriction. Isolated nerve fibres from lumbar spinal roots and sciatic nerves were investigated with reference to the relation between length and diameter of internodes as well as variation of internodal length along single nerve fibres. The present results do not support the view that protein-calorie malnutrition should cause neuropathy. Internodal segments were, on an average, shorter in relation to their thickness in young rats submitted to severe protein restriction or a 50% food reduction. The deviation was most marked in low-protein animals and particularly among coarser internodal segments. An inhibition of longitudinal growth was considered to be the main factor behind the difference between malnourished and normal rats.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00689760
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  • 33
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    Electronic Resource
    Ultrastructural studies on blood-brain barrier dysfunction after cerebral air embolism in the rat (1978)
    Springer
    Acta neuropathologica 44 (1978), S. 53-56 
    Details
    ISSN: 1432-0533
    Keywords: Blood-brain barrier ; Air embolism ; Horseradish peroxidase ; Cerebral cortex ; Electron microscopy ; Carotid artery ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Male albino rats were anaesthetized with diazepam, injected with horseradish peroxidase and Evans blue-labeled albumin and given an embolus of 0.01 ml air in the right common carotid artery after ligation of the external carotid branch. The pial arteries of the right cerebral hemisphere were stained blue, particularly the middle cerebral artery and its main arterial branchlets. Ultrastructurally, some endothelial cells in the right middle cerebral artery, small arteries and arterioles showed a diffuse distribution of horseradish peroxidase in their cytoplasm, although these vessels only occasionally showed peroxidase in their basement membranes. Other endothelial cells in these arterial branchlets showed few if any signs of a diffuse distribution of peroxidase but displayed several pinocytotic vesicles and occasionally trans-endothelial channels filled with peroxidase, sometimes with a slight leakage of peroxidase into adjacent basement membranes and neuropil. Scattered pinocytotic vesicles were observed in capillaries and venules, but there was usually no extravasation of peroxidase around these vessels.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00691639
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    Electronic Resource
    Accelerated development of tolerance during repeated cycles of ethanol exposure (1978)
    Springer
    Psychopharmacology 60 (1978), S. 59-65 
    Details
    ISSN: 1432-2072
    Keywords: Ethanol ; Tolerance ; Behavioral augmentation ; Physical dependence ; Carry-over ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Adult male rats were subjected to 1–4 cycles of daily gastric intubation with ethanol (6 g/kg) for 16 days, separated by 17-day alcohol-free periods. Tolerance produced by this treatment (designated ‘physiological tolerance’) was measured by change in effect of a 2.2 g/kg i.p. dose of ethanol on the moving-belt test. It occurred in each cycle, disappeared completely in the drug-free periods, and developed more rapidly in the second and later cycles than in the first. Tolerance produced by the ‘behavioral augmentation’ technique (daily test practice under the influence of ethanol) also developed more rapidly on a second than on a first cycle. The progression from within-session to between-session tolerance was still evident, but accelerated. With 25-day alcohol cycles, separated by a one-month drug-free period, the ‘carry-over’ effect (i.e., more rapid acquisition of tolerance in the second cycle) applied equally, regardless of whether or not tolerance was produced by the same technique in both cycles, or by a crossover in either direction between the two techniques.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00429180
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    Some effects of chlordiazepoxide and d-amphetamine on response force during punished responding in rats (1978)
    Springer
    Psychopharmacology 56 (1978), S. 211-215 
    Details
    ISSN: 1432-2072
    Keywords: Chlordiazepoxide ; d-Amphetamine ; Response force ; Punishment ; Stereotyped behavior ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Rats were reinforced with water on a continuous reinforcement schedule and were also punished with electric shock for every fifth response applied to a silent, isometric, force-sensing manipulandum. Oral doses of chlordiazepoxide (3.0, 9.0, 27.0 mg/kg) increased both conventional rate and force of punished responding. In contrast, d-amphetamine (0.8, 1.6, 3.2 mg/kg, by gavage) further decreased conventional rate and force of response, but this latter drug increased the rate of recorded responses that were lower than the 15-g force criterion for response consequences. The results for chlordiazepoxide are viewed in terms of its anxiolytic properties, while the d-amphetamine data appear to support a theory of amphetamine effects based on the concept of stereotyped behaviors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00431852
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    Electronic Resource
    Rat intestinal brush border enzymes release by deoxycholate in vivo (1978)
    Springer
    Pflügers Archiv 373 (1978), S. 133-138 
    Details
    ISSN: 1432-2013
    Keywords: Deoxycholate ; Intestinal perfusion ; Rat ; Enzymatic release ; Localization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The release of proteins, sucrase (SA), maltase (MA), leucine aminopeptidase (LA) and alkaline phosphatase (AP) activity from rat jejunum by sodium deoxycholate (DOC) was studied by an in vivo perfusion technique. In our experimental conditions, a 2 mmol/l DOC perfusion for 30 min induced a marked and reversible release of proteins and hydrolases. When specific activities were considered, each enzyme showed a distinct release pattern. Significantly, the SA release was largely increased, the AP release was decreased and there was no correlation between the releases of SA and AP. Furthermore, the various enzymes recovered into the lumen were solubilized at different extents. SA was chiefly present in a soluble and AP in a particular form. The microscopical appearances showed a slight exfoliation of the epithelial cells from the villous tips but no specific changes when compared to the control group. The results are discussed in terms of enzymic localization in the brush border membrane; SA would be located very superficially in the surface membrane and AP buried in the membrane and less accessible than the other enzymes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00584851
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    Dissociation between antidiuretic response and renal medullary cyclic AMP levels in the rat (1978)
    Springer
    Pflügers Archiv 374 (1978), S. 229-234 
    Details
    ISSN: 1432-2013
    Keywords: Cyclic AMP ; ADH ; Vasopressin ; Isoproterenol ; 3-isobutyl-1-methylxanthin ; Rat ; Water diuresis ; Antidiuresis ; Dehydration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In vivo experiments were performed in male Wistar rats to elucidate the probable relation between renal concentrating ability and medullary cyclic AMP content as influenced by changes of hydration and by administration of antidiuretic hormone (ADH). Cyclic AMP levels were 37% lower in water diuretic than in control animals (P〈0.01), but were not significantly changed during prolonged antidiuresis induced by dehydration or ADH administration. Nor could any change of cyclic AMP levels be demonstrated between 2 and 20 min after ADH injection. Significant increases of medullary cyclic AMP content occurred following stress, anesthesia, and administration of isoproterenol and 3-isobutyl-1-methylxanthin. The results suggest that the level of cyclic AMP in the renal medulla may not be an important determinant of the antidiuretic response produced by ADH in rats.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00585599
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    Rasterelektronenmikroskopische Studien am Epithel der Plica vocalis von männlichen Albinoratten (1978)
    Springer
    European archives of oto-rhino-laryngology and head & neck 220 (1978), S. 201-212 
    Details
    ISSN: 1434-4726
    Keywords: Plica vocalis ; Epithelial surface ; Rat ; Extrapulmonary airway epithelium ; Scanning electron microscopy ; Stimmbänder ; Epitheliale Oberfläche ; Ratte ; Larynxepithel ; Rasterelektronenmikroskopie
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Das Stimmbandepithel ausgewachsener männlicher Albinoratten wird rasterelektronenmikroskopisch untersucht. Seine Oberflächenstruktur wird mit jener des Epithels auf der Plica ventricularis und im Recessus ventricularis verglichen. Charakteristischerweise zeigen die Zellen im Epithel über den Stimmbändern einen dichten, lückenlosen Besatz mit Mikrovilli. Die Übergänge des Stimmbandepithels in die benachbarten Larynxabschnitte wird dokumentiert. Besondere Aufmerksamkeit wird dem Auftreten von Mikroleisten auf den apikalen Zellpolen im Larynxepithel gewidmet, die bisher als charakteristische Struktur für das Stimmbandepithel gewertet wurden.
    Notes: Summary The epithelial surface of the Plica vocalis in adult male rat is studied by scanning electron microscopy. It's structure is compared with that of the plica and of the recessus ventricularis. The transition of the epithelium in the plica vocalis to the epithelium of the joining parts of the larynx is documented. Special attention is paid to the occurrence of microridges at the apical poles of epithelial cells in the larynx. Up to now microridge cells have been said to be characteristic for the plica vocalis.
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    URL: http://dx.doi.org/10.1007/BF00457488
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    Electronic Resource
    Some observations on the efferent innervation of rat soleus muscle spindles (1978)
    Springer
    Experimental brain research 31 (1978), S. 433-443 
    Details
    ISSN: 1432-1106
    Keywords: Rat ; Soleus ; Fusimotor innervation ; Skeletofusimotor innervation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In the small segmental tail muscles of the rat beta fibres provide exclusively the dynamic fusimotor control, while gamma fibres provide exclusively the static fusimor control. The present experiments were made to investigate the fusimotor innervation of spindles in a large muscle of the rat, the soleus, and thus to determine the occurrence and significance of beta innervation in this muscle. Our results have revealed no case of beta innervation in the rat soleus. As a consequence of our experimental method, however, we would not claim that beta innervation does not exist in the soleus, only that it must play an insignificant role relative to that seen in the tail segmental muscles. Investigations of the fusimotor innervation of eight spindles were sufficiently complete to warrant detailed illustration. The number of gamma fibres ranged from two to four. In every case the slowest conducting gamma fibre was dynamic. However, the conduction velocity spectra for the static and dynamic gamma fibres to rat soleus overlap to such an extent that it is impossible to use conduction velocity as the sole guide to functional gamma fibre classification. The pooled results from the eight spindles fully investigated provide a ratio of static to dynamic gamma fibres of approximately 1:1. Other evidence discussed in the paper suggests that in the muscle nerve the ratio is considerably higher. These differences are reconciled if the dynamic gamma fibres branch more profusely and innervate more spindles than do the static gamma fibres.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00237300
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  • 40
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    Electronic Resource
    Hippocampal place units in the freely moving rat: Why they fire where they fire (1978)
    Springer
    Experimental brain research 31 (1978), S. 573-590 
    Details
    ISSN: 1432-1106
    Keywords: Hippocampus ; Place units ; Unit recording ; Sensory cues ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Place units in the dorsal hippocampus of the freely-moving rat signal the animal's position in an environment (place field). In the present experiments, thirty four place units were recorded in two different environments: one, a small platform where the rat had received neither training nor reward; the other, an elevated T-maze inside a set of black curtains where the rat had been trained on a place discrimination. The places within the curtained enclosure were specified by four cues (a light, a card, a fan, and a buzzer) in addition to the food. Other cues were eliminated by rotating the maze and the four controlled cues relative to the external world from trial-to-trial. Some units had place fields in both environments while others only had a place field in one. No relationship could be seen between the place fields of units with fields in both environments. All twelve units tested extensively in the controlled enclosure had place fields related to the controlled cues. Probe experiments in which only some of the controlled cues were available showed that some of these units were being excited by one or two cues while others were influenced in a more complex way. The fields of these latter units were maintained by any two of the 4 cues and were due to inhibitory influences which suppressed the unit firing over the rest of the maze.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00239813
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  • 41
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    Electronic Resource
    Hypothalamically induced intraspecific aggressive behaviour in the rat (1978)
    Springer
    Experimental brain research 32 (1978), S. 365-375 
    Details
    ISSN: 1432-1106
    Keywords: Intraspecific aggression ; Lateral hypothalamus ; Electrical stimulation ; Specificity ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The effects of electrical stimulation of the lateral hypothalamus (LH) of rats on intraspecific aggressive behaviour were studied. In order to investigate the specificity of the stimulation effects, each experimental animal was stimulated in a number of different social situations. Stimulation of the LH in the presence of a subordinate male increased the amount of time spent on aggressive behaviour patterns and locomotion. In the presence of a dominant male, however, the stimulated animal never initiated a fight, whereas in the presence of an estrous female attack occurred in some rare occasions and sexual behaviour disappeared almost entirely. Stimulation of some sites also elicited mouse killing behaviour. Many of the electrodes that elicited intraspecific aggressive behaviour also supported intracranial self-stimulation. It is concluded that 1. electrical stimulation of this area of the LH predominantly potentiates intraspecific aggressive behaviour, 2. that this behaviour becomes overt depends on the external situation, including the behaviour of the opponent.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00238708
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  • 42
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    Electronic Resource
    Membrane-associated adenosine triphosphatase in normal and injured hypoglossal nuclei (1978)
    Springer
    Experimental brain research 33 (1978), S. 213-225 
    Details
    ISSN: 1432-1106
    Keywords: Rat ; Hypoglossal nucleus ; Axotomy ; ATP-ase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The hypoglossal nuclei of adult male albino rats, either normal, or from 1 to 70 days after left hypoglossal nerve transection, were studied cytochemically with a lead method for sodium- and potassium-activated membrane ATP-ase, using light and electron microscopy. Reaction product was measured at the light microscopical level by microdensitometry, and significance determined statistically. Light microscopy revealed a brown reaction product in the neuropil, but none in cell bodies. Blood vessel walls were more strongly coloured. Reaction product was undiminished by ouabain pre-incubation, or by incubation without sodium or potassium, or by incubation with calcium instead of magnesium. Reaction product was diminished by absence of magnesium if calcium was also absent, and abolished if sections were boiled before incubation, or if substrate was absent. Axotomy caused a statistically significant increase in neuropil reaction product in injured nuclei, maximal at 35 days postoperatively, and subsequently decreasing to normal at 70 days. Electron microscopy showed a predominantly surface membrane reaction product, with occasional positive intracellular cisternae. Basal lamina and intra-endothelial vacuoles were also positive. Axotomy resulted in the arrival and disappearance of microglia (2 to 35 days), followed by astrocyte hypertrophy (35 days), and increase in thickness and homogeneity of surface membrane reaction product. The results suggest the presence of one or more calcium- or magnesium-dependent membrane ATP-ases. The peak of the increase after axotomy is probably partly attributable to hypertrophic astrocytes, and partly to the surfaces of neuronal processes. Increase of membrane movements might explain such enzyme activity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00238061
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    Electronic Resource
    Technique of continuous collection of parotid saliva in the rat (1978)
    Springer
    Research in experimental medicine 172 (1978), S. 247-253 
    Details
    ISSN: 1433-8580
    Keywords: Rat ; Parotid saliva
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A method is described, which is suitable to collect continuously and quantitatively saliva from both parotid glands in rats under in vivo conditions and which allows to investigate salivary electrolyte composition in relation to flow rate during several hours. This might be of expanding scientific interest in disturbances of transepithelial electrolyte transport in various pathophysiological situations (for instance different forms of experimental hypertension, endstage renal failure and so on).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01855835
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  • 44
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    Electronic Resource
    Sauerstoffverbrauch und Gewichtsentwicklung chronisch urämischer Ratten (1978)
    Springer
    Research in experimental medicine 173 (1978), S. 239-244 
    Details
    ISSN: 1433-8580
    Keywords: Experimental chronic uremia ; Rat ; Oxygen consumption ; Body weight ; Experimentelle chronische Urämie ; Ratte ; Sauerstoffverbrauch ; Körpergewicht
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Die verminderte Gewichtszunahme bei experimenteller chronischer Urämie führte zu der Bestimmung des Sauerstoffverbrauches chronisch urämischer Ratten und eines normalen Vergleichskollektivs. Die Messung des Sauerstoffverbrauches wird als Hinweis auf den Energiebedarf des Gesamtstoffwechsels gewertet. Drei Gruppen von Versuchstieren wurden untersucht: urämische Ratten (CU) von geringerem Gewicht (403,66 ± 9,9 g) als deren gesunde Vergleichstiere (NA) (498,31 ± 26,13) und jüngere Normaltiere (NJ), welche ein annähernd ähnliches Körpergewicht wie die chronisch Niereninsuffizienten aufwiesen (376,0 ± 8,8). Signifikante Unterschiede des Sauerstoffverbrauches, bezogen auf das Körpergewicht, wurden zwischen den Gruppen NJ (0,927 ± 0,042 ml O2/mn/100 g Ratte) und beiden Gruppen CU und NA (0,788 ± 0,036 und 0,788 ± 0,028 jeweils) gefunden. Eine proportionale Verminderung der energetisch aktiven Körpermasse mag die Ursache der Sauerstoff-Meßergebnisse bei chronischer experimenteller Urämie sein.
    Notes: Summary Impaired weight gain, a common feature in experimental chronic uremia, led to compare oxygen consumption values of chronic uremic rats and their controls. Oxygen consumption measurement may allow an approach to the evaluation of total energy requirement. Three groups of animals were considered: uremic rats (CU) of less weight (402.66 ± 9.9 g) than their control group (NA) (498.31 ± 26.13) and younger normal animals (NJ), showing a similar weight (376.0 ± 8.8) to that of the uremics. Significant differences in oxygen consumption values/body weight were found between group NJ (0.927 ± 0.042 ml O2/mn/100 g rat) and both groups CU and NA (0.788 ± 0.036 and 0.788 ± 0.028 respectively). Proportional decrease of energetically active body mass in chronic uremic animals may be the reason of the findings.
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    URL: http://dx.doi.org/10.1007/BF01851495
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    Complement system in sodium taurocholate pancreatitis in the rat (1978)
    Springer
    Research in experimental medicine 174 (1978), S. 57-65 
    Details
    ISSN: 1433-8580
    Keywords: Complement system ; Sodium taurocholate ; Acute experimental pancreatitis ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The role of the complement system was studied in Na-taurocholate pancreatitis in rats. Complement activity (CH 50) was determined at various times in the course of pancreatitis. Immediately after induction of acute pancreatitis, serum complement activity declined and massive C 3 deposits could be detected in the vicinity of acinar necroses and necrobioses. After a phase of recovery three to six hours postoperatively a second complement consumption occurred. Lethality rate increased as serum complement activity fell below 50% of preoperative values. The degree of C 3 deposition increased up to six hours. Decline of serum complement activity and deposition within the pancreas seemed to be correlated with histologically demonstrable tissue lesion. The first decline of complement activity in serum is thought to be caused by liberation of complement activating substances within the pancreas due to the detergent action of Na-taurocholate itself. The second decline, however, may be due to the liberation of complement activating and/or destroying enzymes into the blood stream.
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    URL: http://dx.doi.org/10.1007/BF01851939
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  • 46
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    Resting values of left ventricular work to coronary blood flow ratio in rats exposed to intermittent high altitude hypoxia and swimming (1978)
    Springer
    European journal of applied physiology 39 (1978), S. 173-179 
    Details
    ISSN: 1439-6327
    Keywords: Exercise ; Altitude ; Left ventricular work ; Myocardial blood flow ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Total hemodynamic values and left ventricular blood flow were studied using Sapirstein's method of 86Rb uptake in female rats 24 h after a last exposure to high altitude. A simulated altitude of 1350 m was used, initial exposure being for 30 min, gradually increased by 30 min daily up to 330 min daily for 5 days a week; the total number of exposures was 32. In another animal group the hypobaric exposure was combined with swimming in water at 37
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    URL: http://dx.doi.org/10.1007/BF00421344
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  • 47
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    Hypothalamic and extrahypothalamic distribution of somatostatin-immunoreactive elements in the rat brain (1978)
    Springer
    Cell & tissue research 195 (1978), S. 499-513 
    Details
    ISSN: 1432-0878
    Keywords: Somatostatin neurons ; Hypothalamic, extrahypothalamic distribution ; Immunohistochemistry ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Using a highly sensitive antibody to somatostatin, its hypothalamic and extrahypothalamic distribution in the rat was re-examined by light microscopic immunohistochemistry (PAP-method). The scattered somatostatin-producing perikarya occur in multiple layers within the subependymal neuropil surrounding the third ventricle. They supply with short-distance projections the following hypothalamic nuclei: 1) preoptic nuclei (especially their suprachiasmatic and medial components), 2) the peripheral zones of the suprachiasmatic nuclei, 3) the ventromedial and 4) arcuate nuclei, and 5) the ventral premammillary nuclei. Furthermore, the following long-distance projections have been observed: In a rostral direction (A1) rostral of the anterior commissure to the lamina terminalis, (A2) to the OVLT, (A3) to the olfactory tubercle, and (A4) rostrally and caudally by-passing the anterior commissure to the dorsal part of the stria terminalis. More caudally, at the retrochiasmatic level an ascending dorso-lateral projection joins the ventral amygdalo-hypothalamic pathway in a reciprocal manner (B1). In addition, a descending ventrolateral tract projects to the optic tract bending dorsal to it in different directions: (C1) medial to the median eminence, (C2) lateral to the corticomedial amygdala, and (C3) caudal for additional support of the arcuate and ventral premammillary nuclei. The principal tract of somatostatin-containing fibers descends in the subependymal neuropil to the median eminence (D). The results are discussed with reference to a possible participation of the somatostatin fiber system in the afferent branch of the circuit connecting the hypothalamus with the amygdala via the stria terminalis.
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    URL: http://dx.doi.org/10.1007/BF00233892
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  • 48
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    Influence of maternal adrenalectomy on the ultrastructure of the adrenal gland in neonatal rats (1978)
    Springer
    Cell & tissue research 189 (1978), S. 277-286 
    Details
    ISSN: 1432-0878
    Keywords: Maternal adrenalectomy ; Rat ; Influence on the adrenals of newborn animals ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Maternal adrenalectomy at 7 or 14 days of gestation produced increased cell necrosis within zona reticularis cells on the day of birth and at 24 or 48 h after birth. Small remnants or large portions of adrenocortical cells were present within macrophages. In otherwise normal adrenocortical cells, lipid droplets were incorporated within some mitochondria. Autophagocytosis of single mitochondria was observed within adrenocortical cells. Undoubtedly ultrastructural changes represent stimulation of adrenocortical cells in neonatal rats in response to maternal adrenalectomy.
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    URL: http://dx.doi.org/10.1007/BF00209277
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  • 49
    Electronic Resource
    Electronic Resource
    Investigations into the mechanism of hormone release by rat adrenocortical cells (1978)
    Springer
    Cell & tissue research 189 (1978), S. 403-407 
    Details
    ISSN: 1432-0878
    Keywords: Adrenal gland ; Rat ; Vinblastine ; Corticosterone ; Exocytosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Vinblastine treatment blocks corticosterone release from rat adrenal zona fasciculata without impairing hormone synthesis, and induces the formation of acid phosphatase-positive granular clumps at the juxta-sinusoidal pole of the cells. Autoradiography shows that ACTH administration to vinblastine-treated animals mobilizes the 3H-cholesterol stored in the lipid droplets and leads to a noticeable labelling of the granular clumps. The possible significance of these granules is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00209129
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  • 50
    Electronic Resource
    Electronic Resource
    Kinetics of gametogenesis (1978)
    Springer
    Cell & tissue research 190 (1978), S. 61-68 
    Details
    ISSN: 1432-0878
    Keywords: Oogonia and M-prospermatogonia ; Rat ; Duration of the S-phase and the minimal generation time ; Comparative autoradiographic studies
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung Bei der Ratte tritt die letzte Generation der Oogonien und “multiplying prospermatogonia” (M-prospermatogonia), die häufig in Form synchronisierter “Cluster” angeordnet sind, um den Tag 17 post conceptionem (p.c.), in die Mitose. Die S-Phasen-Dauer D-S-Duration und die minimale Generationszeit T min der weiblichen und männlichen “Gonien” wurden nach der Methode der markierten Mitosen bestimmt (22 weibliche und 22 männliche Feten von 11 Muttertieren wurden 2–22 Std nach einmaliger i.p. Injektion mit 3H-thymidin getötet). Die drei Kurven markierter Prophasen, Metaphasen und der postmitotischen Abkömmlinge, d.h. der Postmitosephasen der Oocyten und primary transitional prospermatogonia” (T1-prospermatogonia), wurden ausgewertet. Die Auswertungen ergaben, daß der Verlauf der einander entsprechenden Markierungskurven von Prophasen, Metaphasen und Postmitosephasen sowie die daraus errechneten Werte für D-S-Duration und Tmin weitgehend übereinstimmen. Die gewonnenen Werte liegen zwischen 10 und 12,5h für D-S-Duration (10h entsprechend dem Verlauf der markierten Metaphasenkurven) und 16,5 und 18h für Tmin (16,5h entsprechend dem Verlauf der markierten Metaphasenkurven).
    Notes: Summary In the rat the last generation of oogonia and multiplying prospermatogonia (M-prospermatogonia), frequently arranged in synchronized clusters, enters mitosis on about day 17 post conception (p.c.). The duration of the S-phase D-S-Duration and the minimal generation time T min of both kinds of “gonia” were determined by the method of labeled mitoses (22 female and 22 male fetuses derived from 11 pregnant rats were sacrificed from 2 to 22 h after a single i.p. injection of 3H-thymidine on day 17 p.c.). Three curves, derived from the labeled prophases, metaphases and the postmitotic descendents of oogonia and M-prospermatogonia — oocytes and primary transitional prospermatogonia (T1-prospermatogonia) — were evaluated. It was demonstrated that the curves as well as the calculated values of D-S-Duration and T min are very similar for oogonia and M-prospermatogonia. D-S-Duration ranged from about 10 to 12.5 h (10 h read off from the curves of labeled metaphases), T min from 16.5 to 18 h (16.5 h read off from the curves of labeled metaphases).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00210036
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    Electronic Resource
    Evidence for amygdaloid projections to the contralateral hypothalamus and the ipsilateral midbrain in the rat (1978)
    Springer
    Cell & tissue research 191 (1978), S. 183-186 
    Details
    ISSN: 1432-0878
    Keywords: Amygdaloid body ; Hypothalamus ; Midbrain ; Autoradiography ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Light microscopic autoradiography was performed subsequent to injection of tritiated amino acids into various parts of the amygdaloid body of the rat. Evidence is provided for two hitherto unreported projections of the amygdala: from the medial amygdaloid nucleus to the contralateral premamillary nuclei and from the central amygdaloid nucleus to the mesencephalic central grey. The functional implications of these findings are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00223226
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  • 52
    Electronic Resource
    Electronic Resource
    Intranuclear microfilament bundles in the ependymal cells of the third ventricle of the rat (1978)
    Springer
    Cell & tissue research 194 (1978), S. 353-359 
    Details
    ISSN: 1432-0878
    Keywords: Intranuclear microfilament bundles ; Third ventricle ; Ependymal cells ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Intranuclear microfilament bundles were observed in ependymal cells of the third ventricle of the rat. They appeared as single, cylindricallyshaped fibrillar bands up to 4.9 μm in length. In cross sections of bundles, the microfilaments exhibited an apparently regular arrangement. They were separated by a distance of 4 to 5 nm, measuring approximately 11 nm from centre to centre. One bundle consisted of 55 to 88 microfilaments. The intranuclear bundles terminated at the inner membrane of the nucleus. They exhibited close spatial relationship to perinuclear chromatin, chromatin centres, intrachromatin granules and fibrillar structures. The average ratio of nuclear sections with and without bundles was 1∶15.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00220401
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  • 53
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    Electronic Resource
    A determination of the volumes of the layers of the rat hippocampal region (1978)
    Springer
    Cell & tissue research 188 (1978), S. 345-359 
    Details
    ISSN: 1432-0878
    Keywords: Hippocampal subfields ; Rat ; Volumes ; Timm stain
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The absolute volumes of the hippocampal and subicular cortical layers in the rat were determined. The boundaries of the various layers were defined on series of sections made through the entire hippocampal region of five rats and stained according to the Timm sulfide silver technique. Coordinates representing the boundaries of the layers on selected sections were fed into a mini-computer programmed to calculate the volume of the layers from the areas of the profiles and the distances between the sections. The distribution of the layers indicates that they constitute the same proportion of the volume of the dorsal and ventral divisions of the hippocampal region, with the exception of the structures lying in regio inferior and regio superior. Although the combined regio superior and regio inferior components of the layers of Ammon's horn occupy the same percentage of the volume of the dorsal and ventral hippocampal regions, the regio superior components occupy a larger percentage of Ammon's horn in the dorsal region than they do in the ventral region. The inter-animal variations in the volumes of the various layers indicate that it is possible to describe quantitatively the subdivisions of the hippocampal region with a precision that is compatible with comparative studies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00219777
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  • 54
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    Electronic Resource
    Quantitative observations of the effect of sex-steroids on the postnatal development of LH-cells (1978)
    Springer
    Cell & tissue research 188 (1978), S. 491-496 
    Details
    ISSN: 1432-0878
    Keywords: Castration ; LH-cells ; Rat ; Development ; Sex-steroids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The effects of sex-steroids on the LH-cell development in neonatal rats were studied. The cells were stained immunohistochemically by applying anti-HCG serum. On the second day after birth some of the animals of both sexes were gonadectomized and simultaneously injected with testosterone or estradiol (50 or 200 μg). The remaining animals were either gonadectomized or injected with either one of the sex-steroids. The LH-cell numbers in each group were determined on the 12th day of age from serially cut histological sections of the pituitary. In castrated males the number of LH-cells was about twice that of the intact animals. In the so-called sex-zone, LH-cells tended to be hypertrophied in castrates. These alterations in the appearance of LH-cells did not occur after ovariectomy. In gonadectomized animals injected with sexsteroids (200 μg), the cells were markedly reduced in number and size, both in males and females. Testosterone injection (50 μg) into intact newborn animals also suppressed the numerical development of LH-cells, especially in females. These alterations were particularly evident in the sex-zone in both sexes. Thus the present findings show that sex-steroids may be involved in sexual differences in morphological development of LH-cells in newborn rats.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00219786
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  • 55
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    Electronic Resource
    Intranuclear inclusions in pericytes of the hypothalamus of the rat (1978)
    Springer
    Cell & tissue research 193 (1978), S. 315-322 
    Details
    ISSN: 1432-0878
    Keywords: Intranuclear inclusions ; Pericytes ; Hypothalamus ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary This paper deals with the ultrastructure of two types of intranuclear inclusions, “nuclear bodies” and “membranous lamellar bodies”, present in hypothalamic pericytes of intact adult rats. The nuclear bodies exhibited “simple” and “granular” forms, whereas the membranous lamellar bodies were entirely made up of myelin-like membrane whorls. The occurrence of these bodies in nuclei of pericytes has never been previously reported. The origin and functional meaning of such structures is discussed in the light of recent ultrastructural and biochemical studies on nuclear inclusions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00209043
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  • 56
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    Electronic Resource
    Regeneration of the vallate papilla in the rat with special reference to the origin of the taste bud-bearing epithelium (1978)
    Springer
    Cell & tissue research 193 (1978), S. 399-411 
    Details
    ISSN: 1432-0878
    Keywords: Taste bud ; Vallate papilla ; Regeneration ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The regeneration of the vallate papilla in the rat was studied by both light and electron microscopy. The papillae were excised and regeneration was studied at time intervals of 3 to 45 days. It was found that the vallate papilla is capable of regeneration after both partial and total papillectomies. The regenerated papillae were asymmetrical in shape. Several invaginations, independent of one another, were the equivalent of the original sulcus. Regeneration of the gustatory system occurred at circumscribed portions of the associated Von Ebner glands. The amounts of newly formed taste buds were proportional to the amount of nerve fibers in the subepithelial plexus. The regenerated taste buds showed normal histochemical and fine-structural characteristics. The results support the contention of some degree of specificity concerning the epithelium where taste bud regeneration occurs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00225338
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  • 57
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    Electronic Resource
    Intranuclear inclusions in the developing neurons of the rat cuneate nuclei (1978)
    Springer
    Cell & tissue research 193 (1978), S. 525-532 
    Details
    ISSN: 1432-0878
    Keywords: Intranuclear inclusions ; Neurons ; Development ; Ultrastructure ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ultrastructure of intranuclear rodlets, microtubules, fibrillar lattices and membranous inclusions found in the developing cuneate nuclei of rats is described. Rodlets, ranging in diameter from 96–312 nm and in length from 1–2 μm, are made up of tightly packed straight filaments measuring 5–8 nm in diameter. Microtubules with a diameter of 26 nm are clustered together. Fibrillar lattices are made up of fibrils with a diameter of 9 nm arranged in layers or sets. Two to nine sets make up a lattice, with a maximum width of 68 nm, in which the adjacent sets are arranged at an angle to each other. Rodlets and fibrillar lattices occur in 6.8% of the neurons. Membranous inclusions, reported here for the first time in normal neurons, are of 2 types: small vesicles of 0.1–0.6 μm and large vacuoles measuring 1–2 μm. Both types are bounded by either a single or a double membrane and generally have an electron lucent content. Membranous inclusions occur in 25.3 % of the neurons. Changes in the frequency of occurrence of the various intranuclear inclusions in the course of postnatal development are also reported.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00225348
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    Electronic Resource
    Masthead (1978)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 18 (1978) 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760180201
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  • 59
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    Electronic Resource
    The use of urethane rubber/epoxide resin blends as matrix materials for glass and carbon fiber compositesPresented 32nd. S.P.I. Conf., Washington, D.C. (Feb. 1977). (1978)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 18 (1978), S. 87-96 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: We consider the effects of using urethane rubber/epoxide resin blends as matrices for unidirectional glass and carbon fiber and for balanced-weave glass fiber cloth composites. The mechanical properties of the unreinforced resin and various composites were measured for specimens with matrices containing up to 35 percent of urethane. The properties of the unreinforced resin show very marked changes between 30 and 35 percent of urethane due, it is believed, to the existence of discrete regions of urethane polymer throughout the matrix. The transverse properties of the unidirectional carbon fiber composites are significantly enhanced by the presence of 20 percent of urethane in the matrix without, apart from a decrease in the shear modulus, any marked change in other properties. This could prove useful in the applications of carbon fiber composites. Results for glass fiber materials are less dramatic, possibly because of poorer adhesion between the glass fiber and the urethane. If this is indeed the cause of the results, it should be possible to bring about an improvement for glass fiber composites by using fibers coated with a suitable coupling agent.
    Additional Material: 17 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760180206
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  • 60
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    Electronic Resource
    The production of glass fiber-reinforced poly(butylene terephthalate) on a continuous kneader (1978)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 18 (1978), S. 107-113 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: In poly(butylene terephthalate) based compositions, thermal degradation of the polymer matrix during processing has to be minimized to achieve quality products. Experience has shown a temperature-residence time relationship, indicating that for mixing systems with high product temperatures, the residence time of the product has to be reduced to avoid excessive thermal degradation. The power density of the mixing system is related to the specific energy input and the residence time of the product. From rheology, the power density is also known for a simple shear deformation which can thus be used to characterize the shear intensity of a particular mixing process. Comparing two different mixing systems by their power density provides us with a qualitative better understanding why higher shear is permitted with lower residence time. From theoretical considerations it was found that for a temperature-sensitive product, like PBT, the power density in the mixing operation can be further raised, taking into account that with shorter residence time a higher product temperature is permitted. Production-scale test work was carried out on a 200 mm screw-diameter continuous kneader to investigate the effect of running conditions and screw design on the thermal degradation of two different types of PBT. Results have shown that for the high-viscosity PBT a linear relationship exists between product temperature and the viscosity retained upon compounding. In a two-stage kneader only minor thermal degradation is encountered in the melting section, but conditions become critical in the mixing stage due to the viscosity increase after introducing the glass fibers to the melt. A new feature in compounding thermodegradable products is the addition of unmolten polymer into the mixing stage of the kneader since this leads to a reduction in the product end temperature and, consequently, thermal degradation of the matrix material. The limited results obtained so far indicate that an optimum exists as to the amount of pellets added. At a 15 percent level the product temperature was reduced by 20°C as compared to 10°C at 20 percent. An energy balance carried out on the continuous kneader indicates that because of the low melt viscosity approximately 30 percent of the energy put into the product in the melting section of the kneader originates from external heating. A rough comparison shows that the power density of a continuous kneader is twice that of a single-screw extruder designed for compounding PBT, but, can be tolerated because of the considerably lower residence time in the former mixing system.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760180208
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    On the damage energy of polymers in creepThis paper is based in part on an oral presentation at the VIIth International Congress on Rheology, Gothenburg (1976) (1978)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 18 (1978), S. 42-44 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Creep experiments carried out on transparent and translucent polymers permit the observation of irreversible material damage in the form of crazes or microcracks. The formation of such damage is strongly dependent on the applied stress, temperature and environmental conditions. The first appearance of observable material damage seems to be explicable by an energy criterion. The energy supplied by the external load can be divided into conserved and dissipated parts, each of them causing volume (isotropic) and shape (deviatoric) changes. The different parts of the energy can be computed if the creep-compliance is approximated by a Prony-Dirichlet series with a finite number of terms. Computations carried out for experiments with air as the environmental medium under isothermal conditions show the dependence between the appearance of first visible material damage (crazes or microcracks) and the conserved energy.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760180109
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  • 62
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    The effect of filler packing fraction on plastics properties (1978)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 18 (1978), S. 33-35 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A critical factor in the performance of fillers in plastics composites is the manner in which the particles pack together. This is called the packing fraction; the true volume occupied by a filler divided by its apparent total volume. The means for determining packing fraction and its effect on viscosity and physical, thermal, electrical and economic properties are outlined.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760180107
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  • 63
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    Oriented short glass-fiber composites. IV. Dependence of mechanical properties on the distribution of fiber orientations (1978)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 18 (1978), S. 45-52 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Short glass fiber-epoxy laminates of controlled fiber orientation and distribution were loaded to failure under uniaxial tension. The mechanical characteristics of specimens with different orientation patterns, which were determined experimentally, were compared with analytical predictions based on “Laminate Analogy” methods. Results show good agreement between empirical data and prediction in the case of stiffness, stress-strain relationship and strength based on ultimate strain criteria. A methodology is proposed according to which a well-defined, orthotropic, short fiber reinforced plastic system can be prepared, analyzed, and optimized by tailoring it according to the loading pattern in a similar manner to that of the well-established, continuous fiber reinforced laminates.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760180110
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  • 64
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    The reinforcement mechanism of fiber-glass reinforced plastics under wet conditions: A review (1978)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 18 (1978), S. 128-145 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Reinforcement mechanisms of fiber-glass reinforced plastics (FRP) under wet conditions are reviewed with emphasis on molecular structures of glass/matrix interfaces. Included are studies on glass surface, the glass/coupling agent interface, silane coupling agents on glass surfaces as well as in solution, the coupling agent/matrix interface, extending to the interphase of particulate-filled composites, and matrix resin. For a better understanding of wet strength of FRP, the structures under dry conditions are extensively, reviewed. The chemical bonding theory still dominates other reinforcement theories. The importance of other factors such as orientation of silane coupling agents and the restriction of matrix polymer conformations are also considered. Based on recent development in spectroscopy, molecular level research of the glass/matrix interfaces has been initiated in the past decade, yet only a few spectroscopic investigations on the function of water have appeared. It is concluded that the correlation between spectroscopic investigations and mechanical properties of a FRP is indispensable.
    Additional Material: 32 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760180211
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  • 65
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    Development of stress birefringence and flow patterns during mold fillin and cooling (1978)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 18 (1978), S. 173-179 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: An experimental study was carried out to investigate the development of stress birefringence patterns of molten polymer during the mold filling and cooling operation. For this study, a rectangular mold cavity with glass windows on both sides was constructed, which permitted us to record on a movie film the changes in stress birefringence patterns in the mold cavity during the molding operation, using a circular polariscope. The mold was equipped with an automatic relay system which closes the shut-off valve when the pressure in the mold cavity reaches a predetermined value. The mold was also equipped with both heating and cooling devices, so that either isothermal or non-isothermal injection molding could be carried out. The mold temperature was controlled by thermistor regulated controllers. During the entire cycle of the molding operation, the mold cavity pressure was continuously recorded on a chart recorder, using a melt pressure transducer. The present study shows how molding conditions (namely, injection pressure, melt temperature, mold temperature) influence the distribution of stress birefringence patterns in a molten polymer while it is being injected into, and cooled in, a rectangular mold cavity.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760180302
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  • 66
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    Morphological and physical property effects for solvent cast films of poly-2, 5(6) benzimidazole (1978)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 18 (1978), S. 204-209 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A polybenzimidazole having the structural repeat unit and designated AB-PBI was formed into films by casting or precipitating from dilute solutions. Selected films were swollen in a plasticizing medium arid drawn about 2X. All films were dried in a vacuum oven to aid in the removal of residual solvent and moisture. Wide angle X-ray scattering (WAXS) was used to show the type of ordering found in this material and to indicate the extent of molecular orientation. Neither a glass transition nor a crystalline melting point has been observed for this polymer, A Perkin-Elmer DSC was used to scan the temperature range from -150 to H-400°C in search of secondary transitions. The rheovibron proved more sensitive and a transition was located in the vicinity of -60°C. An activation energy-was determined. The morphology of this polymer is subject to speculation. The ability of the chain to adopt a linear conformation leads to the possibility of a liquid-crystalline nature in solution. A model based on the data in hand is suggested. Stress-strain data was used to compare the mechanical properties of films prepared by several methods as well as to demonstrate the effect of orientation on strength.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760180306
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  • 67
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    Masthead (1978)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 18 (1978) 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760180401
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  • 68
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    Vinyl chloride formation from the thermal degradation of poly(vinyl chloride) (1978)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 18 (1978), S. 404-407 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The volatile products from the thermal degradation of poly(vinyl chloride) (PVC) resins and compounds are shown to contain trace amounts of vinyl chloride. Data presented show the effect of temperature and resin type on the amount of vinyl chloride formed. At the maximum temperatures involved in PVC processing which may reach 210°C., vinyl chloride monomer (VCM) evolution amounts to less than 1 ppm (resin basis). A technique employing a thermogravimetric balance and charcoal adsorption of volatiles is described for studying thermal degradation of PVC. The volatiles are analyzed for vinyl chloride by gas chromatography. Peak identity was confirmed by mass spectrometry.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760180512
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  • 69
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    Masthead (1978)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 18 (1978) 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760180501
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  • 70
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    Corona-discharge treatment of polyethylene films. I. Experimental work and physical effects (1978)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 18 (1978), S. 326-334 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Corona treatment of films, mainly polyethylene, was studied at commercial levels in a small continuous treater. Degree of treatment was characterized by measuring polar and dispersion components of surface energy, ASTM Wipe and ASTM Adhesion Ratio (“peel adhesion”). The chief factors studied were corona current, applied frequency, web speed, dielectric thickness and air-gap thickness between electrode and film. Other factors less intensively investigated were type of film, film additives, aging time after treatment, humidity and corona atmosphere. The polar component of surface energy, γSP, is the key to understanding the changes in adhesive behavior of the films during treatment. We found that, for the equipment used, γSP is accurately given by the equation \documentclass{article}\pagestyle{empty}\begin{document}$$ \gamma _S^P = 16.91\,D^{0.297}\, G^{- 0.404}\, S^{0.303} (1 - e^{- 1.95\,I/S}) $$\end{document} where D = dielectric thick ness and G = air gap, both in mils; S = web speed, ft/min; I = corona current, ma, and γSP is in dyne-cm/cm2. A similarly structured equation describes ASTM Wipe. Using measured surface-energy components for the pressure-sensitive tape used in the peel adhesion test, it was possible to calculate an adhesion interaction for each film on which peel adhesion was measured and to show that it closely correlates with peel strength. Humidity changes in the moderate-humidity range, number of electrodes used and corona frequency had little effect on properties. Slip additives inhibited development of adhesion until treatment levels became high; adhesion properties gradually diminished upon aging of films stored at ambient conditions.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760180415
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  • 71
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    Superdrawn filaments of polypropylene (1978)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 18 (1978), S. 518-526 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Filaments of polypropylene having remarkably high strength and modulus have been prepared by the two-stage drawing process of Clark and Scott (4). In the first stage, un-oriented extruded billet is rapidly drawn to the natural draw ratio of ca 7X in hot silicone oil. The second stage of draw, a post neck draw process termed superdrawing, requires a slow rate of draw at carefully controlled temperatures to achieve maximum property values; the optimum conditions appear to be close to 4 percent/min at 130°C, The highest mechanical properties obtained were a Young's modulus of 22 GPa (240 gdtex, 3 × 106 psi) and a tensile strength of 0.93 GPa (10 gdtex, 1.3 = 105 psi) with an elongation to break of 7 percent. The filaments show a distinctive dead bend lack of recovery, WAXS data indicate high orientation of the molecules. SAXS data show no scattering to a resolution of 40 nm which is interpreted in terms of a continuous crystal matrix in the superdrawn filament. SEM micrographs of fractured filaments reveal a morphology of large fibrils of lath like habit with a thickness of ca. 0.1 μm. A series of experiments relating mechanical properties to the rate and temperature of superdrawing is interpreted in terms of two competing mechanisms; shearing displacement of microfibrils and unfolding of chain-fold blocks. Models are offered to explain the observed mechanical and physical property changes on superdrawing.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760180615
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  • 72
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    Theory of mixing sections in single screw extruders (1978)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 18 (1978), S. 572-576 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A discussion of the effect of deformation on mixing leads to reorientation of fluid interfaces as a proposed mechanism for special “mixing sections” in single screw extruders. Based on the kinematics of mixing it is shown how a mixing section can greatly decrease the amount of work necessary to accomplish extensive mixing through orienting the fluid more favorably for mixing by subsequent shear. Mathematical development quantitatively describes favored configurations of mixing sections. An upper bound for the mixing performance of a simple model of an extruder with special sections is shown to be similar to turbulent mixing. Based on this theory the key actions of the special sections are identified.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760180705
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  • 73
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    Diffusion of vinyl chloride from PVC packaging material into food simulating solvents (1978)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 18 (1978), S. 601-606 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Two models are used to describe vinyl chloride monomer (VCM) diffusion from poly(vinyl chloride) (PVC) packages to food simulating solvents. It was found that when the initial solid concentration in a PVC package is 0,35 ppm: (a) For poor solvents such as water and oils, VCM concentration in the solvent, Cl, theoretically will not exceed 20 ppb. (b) For strong solvents, the volume ratio of package solid/solvent should not exceed 0.1 in order to keep (Cl)max below 20 ppb. (c) It was demonstrated that thickness can be adjusted to give a Cl = 20 ppb at the time equal to the shelf-life of the package. The method can also be used to calculate the initial concentration of VCM in a package which will give a proposed level of maximum Cl when the solvent and package geometry are fixed. VCM diffusion from PVC pressure pipe to pipe fluids was similarly analyzed.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760180709
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  • 74
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    A simplified method for analyzing mold filling dynamicsPortions of this paper were presented at the Society of Rheology Meeting in New York City on March 2, 1977. Part I: Theory (1978)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 18 (1978), S. 577-582 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A graphical method based on dimensional analysis is presented for estimating the injection pressure and clamp force required for injection molding amorphous polymers to form disk-shaped parts with a constant wall thickness. A procedure is suggested for estimating clamp force when the projected area of the mold cavity is smaller than the surface area of one side of the molded part. The results reported here are based on a numerical simulation of a power-law fluid filling a cold mold at a constant injection rate. The dimensionless bulk temperature and the ratios of the nonisothermal injection pressure (clamp force) to the isothermal injection pressure (clamp force) are given as functions of the dimensionless cooling time τ, the Brinkman number Br which characterizes viscous heating, the power-law exponent n, and a dimensionless temperature β which includes the inlet melt and mold wall temperatures and the temperature coefficient for viscosity.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760180706
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  • 75
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    The effect of molecular weight and weight distribution upon polymer melt rheologyPresented at the American Physical Society Meeting, San Diego, California (March 24, 1977). (1978)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 18 (1978), S. 583-589 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A major objective in polymer rheology is to predict a fluid's response to a general deformation from molecular information. A method has been developed which allows one to predict the viscoelastic properties of polymer melts from a limited amount of rheological and molecular data for the polymer. The input parameters are: (a) zero-shear viscosity; (b) molecular weight distribution; (c) temperature and density; and (d) constants relating Graessley's relaxation time to the Rouse relaxation time. The technique then “simulates” a discrete relaxation spectrum using G′ and G″ data from the Rouse theory and finally requires that a continuum model of polymer viscoelasticity be fit to shear viscosity data predicted by Graessley's theory. Examples of the utility of the procedure are given to illustrate the role of molecular weight and weight distribution in determining rheological behavior.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760180707
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  • 76
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    Prediction of diallyl phthalate molding performance from laboratory tests III. Correlation of data from capillary extrusion rheometer, mechanical spectrometer and differential scanning calorimeter (1978)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 18 (1978), S. 607-610 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The purpose of this work was to determine if capillary extrusion rheometer and mechanical spectrometer data can be used to predict the molding performance of a commercially available diallyl phthalate (DAP) compound. In addition, differential scanning calorimetry (DSC) curves of “good” and “bad” batches were statistically analyzed in order to determine if the DSC peak shape is related to the molding performance. It was found that the data obtained from all three techniques correlate very well with the molding behavior of the DAP material studied. Capillary rheometer and mechanical spectrometer results show that lower melt viscosities and lower curing rates are desirable for obtaining satisfactory molding performance. The mathematical moments analysis of DSC curves indicates that DAP batches which molded well give peaks of fairly high symmetry, while all peaks of “bad” batches are skewed to the left. The center of gravity of the former is at a higher temperature and the variance is smaller than the corresponding values of “bad” compounds.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760180710
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  • 77
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    Metal-containing cured resins based on divalent metal salts of ethylene glycol-methacrylate-maleate (1978)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 18 (1978), S. 628-633 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Divalent metal salts of ethylene glycol-methacrylate-maleate in the amorphous state were easily soluble in styrene, methyl methacrylate and ethyl acrylate, to give homogeneous, curable mixtures with high metal content. The viscosities of the mixtures varied depending on the metal present. The mixtures were copolymerized to give metal-containing cured resins of increased compressive strength and Rockwell hardness. Moreover, heat distortion temperature could be improved by introducing Mg or Ca. Of the cured resins studied, the Mg-containing resin showed the best physical properties. Resistance of the metal-containing resins to attack by organic solvents was generally high, whereas greater degradation by aqueous reagents was noted. The thermal behavior of the resins is discussed.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760180805
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  • 78
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    The operating characteristics of twin screw extruders (1978)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 18 (1978), S. 660-667 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The operation of a twin screw extruder processing a powder or granular solid is reviewed. The operating variables of screw speed and barrel temperature profile interact with a number of design parameters -  screw design, die geometry, feed zone geometry and with the material properties, in determining machine performance. The factors that determine output and pressure development are specified in a sequence of block diagrams. The dynamic response of an operating machine to disturbances in the steady state conditions is explained in the light of the established relationships and interpreted in conventional control theory terms. Attention is drawn to the importance of mixing in the chambers formed by the screw channels and of the residence time distribution in determining the quality of the final product.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760180810
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  • 79
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    Crazing of fibrous polymersIssued on NRCC 17001 (1978)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 18 (1978), S. 923-927 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Highly oriented filaments of nylon 6 and polypropylene (PP) are shown to craze when deformed slowly at room temperature. A marked yield point occurs at 20-40 percent elongation. After this point extensive voiding occurs until at fracture the overall density is reduced by ∽25 percent for PP and ∽15 percent for nylon 6. SAXS analysis indicates that for PP the voids are elongated in the fiber axis while for nylon 6 voiding occurs both parallel and perpendicular to the fiber axis. Optical and electron microscopy show typical craze structures. The use of etching demonstrates that crazing occurs across the whole filament cross section. This yielding behavior is shown to be associated with the use of a low temperature of drawing during fiber production and becomes less important when a higher temperature of drawing or a separate annealing step are used. The crazing mechanism is thought to involve progressive separation of interfibril boundaries with the production of elongated voids.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760181203
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  • 80
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    Polymerization of α, α-disubstituted-β-propiolactones and lactams. 9. ABA block copolymers of α-methyl-α-butyl-β-propiolactone and pivalolactone (1978)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 18 (1978), S. 937-942 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: ABA block copolymers were prepared by the anionic polymerization of α-methyl-α-butyl-β-propiolactone, MBPL (B block), and pivalolactone, PL (A blocks). The MBPL block had a very low decree of crystallinity and a glass temperature of - 13°C, so phase separation with extensive crystallization of the PL blocks gave thermoplastic elastomers when the MBPL block constituted the principal and continuous phase. The observed crystallinity and melting point of 40-45°C in the MBPL homopolymer have not been previously reported. Measurements were obtained by electron microscopy of the initial size distribution of the PL domains as a function of copolymer composition and degree of polymerization, and on the effect of annealing on this parameter. Tensile strengths and elongations at break were both less than those previously observed for equivalent ABA block copolymers of PL and α-methyl-α-propyl-β-propiolactone.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760181206
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  • 81
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    Heat transfer to a plastic tape traveling over heated rolls (1978)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 18 (1978), S. 955-962 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Temperature was calculated as a function of lateral and axial position within a thin poly(ethylene terephthalate) (PET) tape traveling alternately over a heated roll and through air. The system consists of a pair of rolls which are internally heated and located in an oven. The centers of the rolls are ten inches apart and the tape makes eight wraps around the roll pair. Three sources of heat transfer to the tape are considered: convection and radiation from the heated rolls, convection from the air, and radiation from the hot oven walls. Calculations were carried out for oven wall temperatures of 100 and 1000°C, air temperatures of 100 and 205°C, and roll surface temperatures of 180 and 235°C. The computations generally indicate that after several wraps the temperature of the outside surface of the tape (i.e., the surface that does not contact the rolls) is essentially the same each time the tape leaves the roll. However, this temperature changes us the tape then travels through the adjacent, downstream air space. Although there is a temperature gradient across the tape, the temperature of the inside surface (i.e., the side that contacts the rolls) exhibits behavior similar to that of the outside surface.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760181209
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  • 82
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    Geometry of fully wiped twin-screw equipment (1978)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 18 (1978), S. 973-984 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The cross section geometry of fully wiped corotating twin screws is derived from simple kinematic principles. A pair of screws can have identical cross sections with each screw running at the same speed, or they can have an unequal number of tips and rotate at different speeds. The more conventional case of equal cross section is reviewed in detail, showing how screw diameter, centerline distance, lead, and number of tips influences design, net volumes, and surface areas. The screw cross section is unique for a given diameter, centerline distance, and number of tips. The construction of the cross section is shown, both for pairs of identical screws, and for screws with a speed ratio. Maps are provided to show applicability of screws with 1, 2, and 3 tips.
    Additional Material: 23 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760181212
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  • 83
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    The effects of thermal treatment, residual solvent, and preswelling on the thermal properties and sorption behavior of poly(2,6-dimethyl, 1,4-phenylene oxide)-polystyrene blends (1978)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 18 (1978), S. 1006-1011 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The effects of thermal treatment, residual solvent, and preswelling on the thermal properties and swelling behavior of solution cast polyblend films of poly(2,6-dimethyl,1,4-phenylene oxide) (PPO) and polystyrene (PS) were determined. Repeated cycling in the DSC analysis of the “as cast” films suggested that the original films contained residual casting solvent and that solvent-induced crystallization occurred in the PPO-rich compositions. Crystallinity was, apparently, eliminated by the first heating cycle in the differential scanning calorimeter. Sorption kinetics and apparent equilibria, characterizing the penetration of these films by n-hexane from the vapor phase, indicated that both the sorption rate and apparent equilibria are significantly affected by the prior history of the film samples. The sorption results presented here are quantitatively consistent with earlier studies of the PPO-PS system. The increased rate and amount of sorption observed in preswollen samples, and the reduced rate and amount of sorption observed in annealed samples are consistent with recent descriptions of sorption behavior in diverse glassy homopolymer systems.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760181307
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  • 84
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    Orientation effects and cooling stresses in amorphous polymers (1978)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 18 (1978), S. 799-811 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: This paper deals with two kinds of internal stresses in amorphous polymers. First, the internal stresses connected with molecular orientation are discussed. A framework is presented that describes the interrelations of the various orientation effects (anisotropy, birefringence, etc.) and their dependence on the thermomechanical history of the material. The second part of the paper deals with the residual thermal stresses generated by rapid inhomogeneous cooling through the glass transition range. These so-called cooling stresses are well-known in glass technology. The theory of the quenching of flat glass plates is described, generalized to objects of arbitrary geometry, and shown to be applicable to polymers. The practical importance of cooling stresses is discussed.
    Additional Material: 20 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760181011
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  • 85
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    Kinetic studies on shear degradation of polystyrene during extrusion (1978)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 18 (1978), S. 812-816 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Kinetic studies on shear degradation of a polystyrene (M̄n = 115,700 and P̄n = 1113) during extrusion in a model extruder were made at different temperatures (170, 190, 210, and 230°C) and shear stresses (340,406, and 472 g/cm2) for determination of rate constants for degradation, reaction order, and effects of temperature and stress on the rate constants. Mechanical energy and effective activation energy (E*) of bond rupture were related to temperature and applied stress. The following results were obtained. The degradation process is found to be satisfied by a second order reaction over the temperatures and stresses studied with respect to the changes in number average chain length (Pt - P∞), thus -dP/dt = k(Pt - P∞)2, where k is a reaction rate constant and t and ∞ refer to degradation times. The mechanical energy of bond rupture has a maximum and the rate constant a minimum at about 180°C, indicating that the least effective temperature for mechanical degradation is about 180°C. E* decreases with increasing applied stress (τ) as a linear relationship, i.e., E* = EA - ατ. At τ = 0, E* becomes equal to the activation energy for thermal degradation with the value EA = 48.6 kcal/mole which agrees well with literature data. Temperature and stress effects on the rate constant are well expressed for our study by the Arrhenius equation proposed by Zhurkov, et al., i.e., k = A exp[-(Ea - ατ)/RT] where A and α are coefficients.
    Additional Material: 8 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760181012
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    The fracture mechanics of polymers at high rates (1978)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 18 (1978), S. 833-839 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Instrumented pendula have been applied to investigate the fracture toughness of some polymeric materials - homopolymers and composites - by fracture mechanics. The method is simple, and can be easily used for routine testing or research work. The load transducer is such that it allows the achievement of very accurate stress-time curves. Data are reported which clearly show the dependence of Kc on speed, temperature, and molecular weight. Kc is the critical stress intensity factor. It has also been found that the Kc experimental values can be correlated with a peculiar feature of the fracture surface for the determination of the intrinsic value of Kc/1 by the use of both the Dugdale model and a simple graphic correlation.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760181016
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  • 87
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    Solubility of vinyl chloride in poly (vinyl chloride) in a water slurry (1978)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 18 (1978), S. 841-843 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The solubility of vinyl chloride (VCM) vapor in poly (vinyl chloride) (PVC) in a water slurry has been measured between 55 and 65°C. The heat and entropy of sorption were shown to be very close to those of condensation. The solubilities measured in this study were higher than those obtained in other studies on dry PVC and PVC latex. The interaction parameter (x) in the Flory-Huggins equation has been shown to vary between 0.34 and 0.61 over the composition range studied. The effect of ageing the slurry in the presence of VCM is also discussed.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760181102
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  • 88
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    Electronic Resource
    Infrared laser ablation of polymers (1978)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 18 (1978), S. 900-904 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Ablation produced by 10.6 μm laser irradiation of eleven polymers is reported. Polymers which formed a carbonaceous residue were found to have much higher ablation energies than cleanly ablating polymers. All non-char forming polymers studied had observed laser ablation energies in the range 3.4-3.9 KJ/g except for poly (α-methylstyrene) which had a value of 2.4 KJ/g. The low value forpoly (α-methylstyrene) is attributed to an exceptionally efficient depolymerization. The observed ablation energy of poly (methyl methacrylate) was found to decrease with increasing irradiance up to about 15 watts/cm2, reaching a constant value of 3.5 KJ/g at irradiances between 20 and 2600 watts/cm2. The proposed process of laser ablation is one that involves random fragmentation resulting from the accumulation of vibronic energy.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760181113
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  • 89
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    Electronic Resource
    The appearance retention properties of poly (vinyl chloride) compounds during weathering (1978)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 18 (1978), S. 905-907 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Damage to poly (vinyl chloride) (PVC) compounds due to thermal degradation during processing has an important influence on its subsequent weatherability. High melt temperatures and/or high residence times cause white PVC to become more yellow and colored PVC to fade and bleach more upon weathering. If high melt temperatures are used, then short residence times are needed to maintain excellent weatherability. In addition to careful consideration of extrusion conditions, stream-lined equipment is necessary to produce extrudate of uniform thermal history. Also, relatively high thermal stabilizer levels help reduce thermal damage and, therefore, improve weatherability. Impact resistance is better retained when processing occurs at higher melt temperatures. A reasonable compromise between extrusion rate and temperature must be reached to provide for adequate color and impact retention.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760181114
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  • 90
    Electronic Resource
    Electronic Resource
    Masthead (1978)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 18 (1978) 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760181201
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  • 91
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    Electronic Resource
    Dispersion viscosity of aluminum trihydroxide of various particle size distributions in an unsaturated polyester resinPresented in part of the St. Louis AIChE Symposium (March 29, 1977) under the title “Searching for the Optimum Particle Size Distribution” (1978)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 18 (1978), S. 928-931 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The effect of filler particle size distribution on the viscosity of an aluminum trihydroxide/unsaturated polyester resin dispersion was studied. Four basic aluminum trihydroxides with distinctively different particle sizes were combined to generate various particle size distributions systematically. The particle size distribution producing the minimum viscosity was determined by employing a modified extreme vertices experiment design for mixtures to establish a quadratic model which was then optimized. The predicted viscosities in general as well as the particle size distribution corresponding to the minimum viscosity agreed well with the observed data.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760181204
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  • 92
    Electronic Resource
    Electronic Resource
    The influence of morphology on the tensile properties of polyethylenes (1978)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 18 (1978), S. 943-950 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The tensile properties of high and low density polyethylene specimens produced under careful crystallization and annealing procedures have been determined. A morphologically controlled brittle-ductile transition has been observed for high density polyethylene. Although the lamellar thickness appears to determine the transition, a postulate involving molecular fractional on during crystallization as the cause is offered. For ductile materials, dependence of the Young's Modulus on morphology is interpreted using the fiber-composite analogy of Halpin and Kardos. Yield stress varies as modulus and achieves maximum values consistent with estimates of the critical resolved shear stress of polyethylene crystals.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760181207
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  • 93
    Electronic Resource
    Electronic Resource
    Elongational flow of polymer melts (1978)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 18 (1978), S. 963-968 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A new technique is described whereby the rate of collapse of an air bubble within a molten polymer may be measured without the need for visual observation. The method involves use of a high speed recording dilatometer, From such data it is possible to measure an apparent elongational viscosity of the melt, and such measurements are presented for two polyethylenes (Tennite, a low density PE, and Plaskon, a high density PE), Limitations of the methods are discussed. This is one of a series of papers (1-3) documenting our development of a new experimental technique, and the corresponding mathematical modeling, whereby one may measure the elongational viscosity of polymeric viscoelastic fluids. Previous experimental work was confined to transparent fluids, since the technique depended on high-speed motion picture photography of the collapse of an air bubble within the fluid. In this paper we describe an attempt, largely successful, to develop a new experimental system which permits the study of molten polymers, including opaque fluids. Sample results are presented for both a low and a high density polyethylene.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760181210
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  • 94
    Electronic Resource
    Electronic Resource
    Effect of gamma radiation and annealing on ultra-oriented polyethylene (1978)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 18 (1978), S. 527-532 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Filaments of ultra-oriented high density polyethylene were solid-state extruded at an extrusion (draw) ratio of 26 and subsequently irradiated under vacuum by a cobalt-60 source at doses of 10,15, 20, 40 and 60 megarads (MRad). Several identically prepared but unirradiated strands were also tested. One set of samples at each dose was immersed in a silicone oil bath for one half hour at 128°C and one set was given no post-irradiation thermal treatment. Characterization of the resultant morphologies included differential scanning calorimetry (DSC), birefringence, thermomechanical analysis (TMA), and tensile testing. Results from DSC measurements indicate that initial radiation crosslinking only slightly disrupts the crystal lattice, but on subsequent melting and re crystallization, the chains are unable to recrystallize effectively in their former habit. In all cases, melting point and crystallinity decrease with increasing radiation dose. Birefringence and TMA results indicate that orientation is not disrupted by irradiation. For unannealed samples, Young's modulus increases slightly then levels off while tensile strength and elongation at break increase initially, then drop, For annealed irradiated samples, Young's modulus rises at first, then levels off at higher doses. Tensile strength and elongation at break increase significantly with increasing radiation treatment, then essentially reach constant values at highest doses.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760180616
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  • 95
    Electronic Resource
    Electronic Resource
    A rigid poly(vinyl chloride) compound with improved combustion characteristics (1978)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 18 (1978), S. 549-555 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: By means of compounding, we have developed a rigid poly(vinyl chloride) (PVC) formulation with improved overall combustion properties. Newly developed analytical methods indicate a considerable reduction in the level of gases released during combustion, in addition to excellent flammability characteristics and low visible smoke emission levels. The analytical methods discussed are expected to aid in the selection of a feasible protocol for biological testing and in the interpretation of results obtained from such testing. The under-lying compounding technology is currently restricted to normal impact rigid PVC cube compounds but expected to be expanded into high impact PVC, flexible PVC, PVC powder compounds and cellular PVC.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760180702
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  • 96
    Electronic Resource
    Electronic Resource
    The thermal conductivity of several plastics determined by an improved line-source apparatus (1978)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 18 (1978), S. 556-563 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The line-source method, previously used for measuring thermal conductivity of plastics, was increased in sensitivity so that automatic recording of data and data reduction by computer could be used, The correspondence between the underlying mathematics and the experiment is examined. The apparatus is described. The effect of experimental variables such as heating rate is determined- Measured values of thermal conductivity are reported for several commercial plastics, from room temperature, or lower, to processing temperatures. The precision of the results is excellent.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760180703
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  • 97
    Electronic Resource
    Electronic Resource
    Masthead (1978)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 18 (1978) 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760180801
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  • 98
    Electronic Resource
    Electronic Resource
    A critical analysis of the use of sample-supportive techniques in the measurement of dynamic mechanical relaxation processes (1978)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 18 (1978), S. 624-627 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: It is shown that the technique of dynamic spring analysis (DSA) gives rise to a dynamic mechanical loss dispersion well above the glass transition temperature, Tg, analogous to the Tu process observed in torsional braid analysis. A mechanical model is proposed which explains why any composite sample consisting of an elastic support coupled to a viscous liquid must necessarily produce such a relaxation regardless of whether the liquid is monomeric or polymeric in nature. Loss tangent measurements performed on a series of polystyrenes of varying molecular weight and on glycerol using both DSA and a Rheometrics mechanical spectrometer show that the relaxation observed in DSA is not of molecular origin.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760180804
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  • 99
    Electronic Resource
    Electronic Resource
    The effect of glass-resin interface strength on the impact strength of fiber reinforced plasticsPresented at the 1977 Reinforced Plastics Conf., Society of the Plastics Industries, Inc. (Feb. 1977). (1978)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 18 (1978), S. 62-72 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The effect of glass-resin interface strength on the impact energy of glass fabric (style 181) reinforced epoxy and polyester laminates has been determined. The interface strength was altered by surface treatment of the fabrics with silane coupling agents and with a silicone fluid mold release and the interlaminar shear strength was determined as a means to evaluate the interface strength. An instrumented Charpy impact test was used on unnotehed specimens and thus both initiation and propagation energies could be determined as well as dynamic strength. It was found that the initiation energy for both polyester and epoxy laminates increased with increasing interlaminar shear strength, The propagation energy and thus the total energy for polyester laminates displays a minimum at a critical value of interlaminar shear strength (ILSS). Below this critical value, the total impact energy increases with decreasing shear strength and the dominant energy absorption mode appears to be delamination. Above the critical value, the impact energy increases with increasing values of ILSS and the fracture mode is predominantly one of fiber failure. In all cases, even with mold release applied, the shear strength of epoxy laminates was above this critical value and-thus the total impact energy increases with Increasing values of ILSS. The maximum energy absorbed for the epoxy laminate and the polyester laminate is nearly identical. However, the maximum for the epoxy laminate occurs when the shear strength is maximized while for the polyester laminate the shear strength must be minimized. For the polyester laminate when delamination is predominant, it was found that the glass surface treatment affects the amount of delamination as opposed to the specific value of delamination fracture work.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760180203
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  • 100
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    Prediction of transport properties of composites from equations of elasticityPresented at 32nd Annual Conference of the Reinforced Plastics/Composite Institute of the Society of the Plastics Industry, Inc., Washington, D.C. (February 8-11, 1977). (1978)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 18 (1978), S. 114-119 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The mathematically-analogous equations of elasticity were used to predict the transport properties of anisotropic composite films. Composite films of controlled structural and physical characteristics were prepared by embedding impermeable glass ribbons in a cellulose acetate matrix. Simple but approximately-precise equations of composite moduli developed by Halpin and Tsai were used to predict the composite permeability in terms of the permeabilities of the constituent phases and a structure factor which is a measure of the filler reinforcement and signifies the resistance of the filler phase to the diffusive flow in the composite medium. The discrepancy between the theoretical predictions and experimental composite permeabilities has been explained in terms of diffusive flux lines not staying in a single direction. In the case of glass ribbons the diffusive1 flow lines tend to bend away from the ribbons (regions of lower permeabilities). The extent of influence of the filler phase to impede the overall composite permeation is a function of the geometry, orientation and volume fraction of the filler.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760180209
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