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  • 1970-1974  (2,689)
  • 1965-1969  (1,941)
  • Physics  (4,396)
  • Cat
  • Psychopharmacology
  • 1
    Electronic Resource
    Electronic Resource
    On different patterns of dendritic bundling in the cerebral cortex of the cat (1974)
    Springer
    Anatomy and embryology 143 (1974), S. 115-126 
    Details
    ISSN: 1432-0568
    Keywords: Cerebral cortex ; Apical dendrites ; Dendritic bundles ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In frontal, horizontal and sagittal paraffin sections through the cat's brain regional differences in the pattern of dendritic bundling have been investigated. It is shown that in the gyrus splenialis and suprasplenialis 2–5 apical dendrites of layer IV pyramids approach each other to form vertical bundles which run straight through layer IV. In the posterior sigmoid gyrus, on the other hand, most apical dendrites arising from the pyramidal cells bifurcate immediately above layer V and give rise to obliquely running branches which cross each other before turning upwards and joining other dendrites to take part in the formation of bundles. In this region the dendritic tree of the pyramidal cells seems to be characterized by an unexpectedly high degree of directional specialization.—In functional terms the findings can be summarized by stating that in the visual and sensorimotor regions of the cat's cerebral cortex basic differences exist in the relation between the apical dendrites of layer V pyramids.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00525764
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  • 2
    Electronic Resource
    Electronic Resource
    Crossed reticulo-reticular projections in the medulla, pons and mesencephalon (1974)
    Springer
    Anatomy and embryology 143 (1974), S. 127-134 
    Details
    ISSN: 1432-0568
    Keywords: Reticular formation ; Crossed connections ; Autoradiography ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Injection of radioactive leucine in various regions of the brain stem reticular formation has revealed the presence of ample crossed reticulo-reticular connections in the cat. The terminal area for the crossed fibers are almost mirror images of the injected sites. The findings made is another example that hitherto unknown fiber connections can be demonstrated by axoplasmic protein tracing.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00525765
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  • 3
    Electronic Resource
    Electronic Resource
    Evolution ultrastructurale du labyrinthe de placenta de chatte (1974)
    Springer
    Anatomy and embryology 146 (1974), S. 1-20 
    Details
    ISSN: 1432-0568
    Keywords: Placenta ; Cat ; Differentiation ; Function ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Résumé L'ultrastructure du labyrinthe de placenta de chatte a été étudiée du 45e au 63e jour de gestation. Cette formation endothéliochoriale est composée: d'un endothélium maternel hypertrophié et de cellules géantes déciduales; d'une couche de «substance inerte interstitielle»; du trophoblaste constitué d'une assise syncytiale continue (syncytiotrophoblaste) et d'une assise cellulaire discontinue (cytotrophoblaste); d'un endothélium foetal accompagné de son environnement mésenchymateux. Les capillaires foetaux envahissent progressivement le syncytiotrophoblaste. L'hypertrophie de l'endothélium maternel diminue en fin de gestation; de ce fait la distance, séparant le sang maternel du sang foetal, peut atteindre en certains points 2 μ. L'endothélium maternel, le syncytiotrophoblaste et l'endothélium foetal présentent des signes ultrastructuraux d'un rôle de transfert. La «substance inerte inerte interstitielle», qui sépare les tissus d'origine maternelle des tissus d'origine foetale, est constante mais d'épaisseur variable; elle est spécifique des structures endothéliochoriales. Les cellules géantes déciduales, dont le nombre diminue en fin de gestation comportent parfois un ou plusieurs «corps glycogéniques». Le syncytiotrophoblaste, siége d'activité de biosynthése de stéroïdes, est riche en ergastoplasme, ce qui autorise à postuler la synthése d'hormones protéiques.
    Notes: Summary The ultrastructure of feline placental labyrinth has been studied from the 45th to the 63rd day of gestation. The endotheliochorial structure is composed of: a thick hypertrophied maternal endothelium with giant decidual cells; an “interstitial inert substance”; a continuous syncytial layer (syncytiotrophoblast) and a discontinuous cellular layer (cytotrophoblast) of trophoblast; and a thin foetal endothelium with its surrounding mesenchyme. Foetal capillaries increasingly invade the syncytiotrophoblast. Maternal endothelial hypertrophy is reduced in the last days of gestation. Thus the interval between maternal and foetal bloods may in some areas become 2 μ, in late pregnancy. Foetal endothelium, syncytiotrophoblast, and maternal endothelium demonstrate ultrastructural features of transfer function. The “interstitial inert substance”, which separates maternal from foetal tissue was always evident though with variable thickness. The giant decidual cells which are reduced in late pregnancy, show one or several “glycogen bodies”. The syncytiotrophoblast, where some steroïd biosynthesis has been demonstrated, has an extensive rough endoplasmic reticulum suggestive of protein hormone synthesis activity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00341379
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  • 4
    Electronic Resource
    Electronic Resource
    Zur histogenese und cytogenese des tapetum lucidum cellulosum der katze (1974)
    Springer
    Anatomy and embryology 146 (1974), S. 141-156 
    Details
    ISSN: 1432-0568
    Keywords: Tapetum lucidum cellulosum ; Cat ; Development ; Light and electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Die postnatale Entwicklung des Tapetum lucidum cellulosum der Katze wird mit licht- und elektronenmikroskopischen Methoden untersucht. Bereits am ersten postnatalen Tag sind im Bereich des prospektiven Tapetum zwei Zellarten voneinander zu unterscheiden: 1. mesenchymale Bindegewebszellen und 2. prospektive Tapetumzellen, die durch elektronendichte Tapetumstäbchen gekennzeichnet sind. Die Mesenchymzellen unterteilen als parallel zur Retinaoberfläche ausgebreitete Zellplatten in der Choriodea am hinteren Augenpol den weiten extracellulären Raum in 20–25 etwa 5 μm hohe Schichten. Die Tapetumzellen liegen zwischen den Mesenchymzellplatten und wachsen im Verlaufe der ersten vier postnatalen Wochen innerhalb der Schichten in die Breite, bis sie den extracellulären Raum vollständig ausfüllen und als polygonale Zellen direkt aneinander grenzen. Im weiteren Verlauf der Entwicklung werden die Mesenchymzellplatten rückgebildet, so daß bei der adulten Katze die Tapetumzellschichten direkt übereinander liegen und nur von Netzen elastischer und kollagener Fasern getrennt sind. Die von einer Elementarmembran umgebenen Tapetumstäbchen enthalten einen elektronendichten, in den ersten postnatalen Wochen mit einer Periode von 100 Å quergestreiften Kern. Zunächst nehmen sie an Zahl und Länge zu und füllen am Ende der vierten postnatalen Woche, zu Bündeln von parallel verlaufenden Stäbchen geordnet, das Cytoplasma der Tapetumzellen. Dann nehmen die Tapetumstäbchen an Dicke zu, und ihre Querstreifung wird von einem elektronendichten Material überlagert. Die Entwicklung der Tapetumstäbchen hat eine starke Ähnlichkeit mit der in der Literatur beschriebenen Entwicklung von Melanosomen in Melanocyten. Das Tapetum lucidum cellulosum wird als ein dichter Verband hochdifferenzierter extrakutaner Melanocyten angesehen.
    Notes: Summary The postnatal development of the tapetum lucidum cellulosum of the cat was studied by light and electron microscopy. Already by the first postnatal day two cell types can be distinguished in the prospective tapeta area: 1. mesenchymal cells and 2. prospective tapetal cells, characterized by electron dense, membrane bound, rod-like inclusions. The flattened mesenchymal elements form 20–25 separate layers of cells, which are arranged parallel to the surface of the retina, subdividing the extracellular space of the chorioidea at the posterior pole of the eye into 5 μm high compartments. These compartments contain the tapetal cells which enlarge (in their longitudinal axis) during the first four weeks post partum until they occupy the extracellular space almost completely. At this stage, the tapetal cells are polygonal in shape and closely attached to each other. During the subsequent period of development there is a gradual involution of the mesenchymal cell plates. Thus, in adult cats the individual layers of tapetal cells are only separated from each other by networks of collagen and elastic fibers. The tapetal rods are bound by unit membranes and contain an electron dense core which, during the early postnatal weeks, exhibits a periodic cross-striation (100 Å). The tapetal rods increase in number and length during the first four weeks post partum; by the end of the fourth week, they occupy the whole cytoplasm of the tapetal cells. Parallelly arranged rods are grouped into individual bundles coursing inside the cytoplasm in different directions. Thereafter, the tapetal rods increase in thickness and their cross-striation becomes obscured by an electron dense material. This development of the tapetal rods closely resembles that of melanosomes. Thus the tapetum lucidum cellulosum can be regarded as a compact tissue made up of modified extracutaneous melanocytes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00315591
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  • 5
    Electronic Resource
    Electronic Resource
    Function and interaction of on and off transients in vision II. Neurophysiology (1974)
    Springer
    Experimental brain research 19 (1974), S. 507-521 
    Details
    ISSN: 1432-1106
    Keywords: Cat ; LGN ; Transients ; Antagonistic inhibition ; Sensory storage
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Neuronal responses to interruptions of light stimuli were studied in 58 X-type and 7 Y-type LGN relay cells with intra- and extracellular recording techniques. The responses to interruption were then compared with responses to either appearing or disappearing light stimuli which had the same luminance and size as the interrupted stimulus. The extent to which responses to interruption differed from those to appearance and disappearance was studied as a function of the interstimulus interval (ISI), the duration of the stimulus before the interruption (t1) and after the interruption (t2). Responses to stimuli appearing after interruptions of up to 500 msec were weaker than those to appearance and disappearance. This difference decreased with increasing ISI. The difference between responses to appearance and interruption increased as t2 decreased, and decreased as t1 decreased. The reverse was true for the difference between responses to disappearance and interruption. Stimulation of the mesencephalic reticular formation consistently reduced the difference between responses to appearance and disappearance compared with those to interruption for all stimulus conditions. These results are discussed in the context of the psychophysical study presented in the preceding paper. It is shown that the neuronal reactions are reflected in detail by the ability of humans to detect appearances and disappearances that occur during interruptions. EPSP sequences recorded from LGN relay cells and relay cell responses conditioned by reticular stimulation suggest that the differentiation of responses to interruption and change partially occurs already in the retina. This differentiation is subsequently enhanced by antagonistic inhibition in the LGN. It is proposed that these inhibitory interactions at peripheral sites of the visual pathway store visual information and serve to reduce the redundancy of responses to short interruptions of the visual input. Centrifugal modulation of LGN inhibition is proposed to control the trade off between temporal integration and temporal resolution.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00236114
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  • 6
    Electronic Resource
    Electronic Resource
    Reflexes in postganglionic fibres within skin and muscle nerves after noxious stimulation of skin (1974)
    Springer
    Experimental brain research 20 (1974), S. 125-134 
    Details
    ISSN: 1432-1106
    Keywords: Somato-sympathetic reflexes ; Cutaneous and muscle postganglionic neurones ; Noxious stimulation of skin ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 1. Somomato-sympathetic reflexes in postganglionic neurones to skin and muscle induced by noxious stimulation of skin were studied in cats anaesthetized with chloralose. The reflexes were elicited by mechanical damaging stimuli and by temperature stimuli of more than 45°C. 2. In most cutaneous units the spontaneous activity was depressed during noxious stimulation of skin. Some cutaneous units were excited or showed mixed responses. The depression of the spontaneous activity was maximal from the skin area which was innervated by the cutaneous postganglionic neurones and much weaker or not elicitable from other skin areas. 3. Most muscle units were excited during noxious stimulation of skin. This excitation could be elicited from all over the body surface. 4. The effective cutaneous afferent fibres which are involved in these reflexes are the Group III axones which are excitable by mechanical damaging stimuli and the Group IV axones which are excitable by mechanical damaging and/or by thermal noxious stimuli. 5. These investigations reveal that the somato-sympathetic reflexes have opposite organization in cutaneous and muscle postganglionic fibres. The reflex patterns are discussed in relation to a possible central organization of the sympathetic nervous system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00234007
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  • 7
    Electronic Resource
    Electronic Resource
    Role of visual experience in the development of optokinetic response in kittens (1974)
    Springer
    Experimental brain research 20 (1974), S. 297-302 
    Details
    ISSN: 1432-1106
    Keywords: Cat ; Selective rearing ; Maturation ; OKN ; Perception of motion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 1. Kittens reared in the dark from birth were exposed one hour a day between the 4th and the 10th week of age, to a visual environment which consisted exclusively of vertical edges moving horizontally at a constant speed, and always in the same direction. Total exposure time varied between 10 and 60 hours. 2. At the 12th week of age, optokinetic nystagmus (OKN) in response to displacements of the visual field, was tested. Displacements in the direction that the kittens had experienced during the exposure period elicited immediately an OKN, the frequency of which was related to the speed of the moving pattern. Displacements in the opposite direction elicited a poorer response, only for slowly moving edges. When the speed of the displacement was increased, OKN failed to adapt and finally disappeared. 3. These results suggest the existence, in this type of visuomotor behavior, of a component built up by early visual experience (adaptative component) overlying another component pre-existing visual experience (pre-programmed component).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00238319
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  • 8
    Electronic Resource
    Electronic Resource
    Attention in the cat: Electrophysiological and behavioural studies (1974)
    Springer
    Experimental brain research 21 (1974), S. 67-82 
    Details
    ISSN: 1432-1106
    Keywords: Sensory transmission ; Lateral geniculate nucleus ; Visual cortex ; Attentive behaviour ; Vigilance ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The behaviour of 6 cats was studied in a vigilance task. Each cat was trained to press a pedal on the floor of a training box. A waiting interval of fixed (FI) or variable (VI) duration then followed, after which a stimulus (S), a spot of light or a tone, was presented for a short period of time. The cat gave a correct response if, during this time, it pressed a panel. The animal was then rewarded with food. When an experiment had been completed using one S the cat was trained to respond to the other. The latency of response following the onset of S was measured for each waiting interval in the VI schedules. It was found that the longer latencies were associated with the shorter waiting intervals; that is, the cats responded more quickly to S as expectancy increased. Between the time the pedal and pand were pressed the optic tract (OT) was shocked not more than once and the response of the LGN and visual cortex recorded. The time at which the shock was delivered varied from 1 trial to the next. The responsiveness of the LGN and visual cortex did not vary during the waiting interval in either of the FI schedules or in the VI schedule in which S was a spot of light. However, in the VI schedule in which S was a tone, the responsiveness of the visual cortex to the thalamocortical input declined as the length of the waiting interval increased. No changes were observed at the LGN or in the presynaptic cortical response. These results contrast with those observed during changes in the level of arousal as assessed by the ECoG. When the ECoG passed from the synchronised to the desynchronised state there was an increase in the amplitude of the postsynaptic LGN response to the OT shock, but no change in the responsiveness of the cortex to the increased thalamocortical input. These changes in transmission in the visual pathways are discussed in relationship to the animal's behaviour and to the inferred state of attention.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00234258
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  • 9
    Electronic Resource
    Electronic Resource
    Electrotonic coupling between motoneurones in the abducens nucleus of the cat (1974)
    Springer
    Experimental brain research 21 (1974), S. 139-154 
    Details
    ISSN: 1432-1106
    Keywords: Electrotonic coupling ; Antidromic responses ; Abducens motoneurone ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The electrical stimulation of the abducens nerve provokes the classical true antidromic invasion of the abducens motoneurone and a depolarization which is often capable of generating full action potentials in the impaled motoneurone. Experiments studying these depolarizations suggest the existence of electrotonic coupling between the abducens motoneurones of the cat. Intracellular activity of the abducens motoneurones was recorded following intracellular stimulation of the impaled neurone and antidromic stimulation of the abducens nerve. Collision between the outgoing action potential and the antidromic volley differentiated the true antidromic spike from the depolarizations which can induce or not action potentials. The latency of the depolarization ranged between 100 and 1200 μsec. Collision demonstrated that the depolarization and the true antidromic action potential have an independent origin. The depolarizations and action potentials which are not conveyed to the motoneurone by its own axon are interpreted to be generated by electrotonic coupling.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00234386
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  • 10
    Electronic Resource
    Electronic Resource
    The lateral reticular nucleus in the cat I. Mossy fibre distribution in cerebellar cortex (1974)
    Springer
    Experimental brain research 21 (1974), S. 473-486 
    Details
    ISSN: 1432-1106
    Keywords: Lateral reticular nucleus ; Reticulocerebellar projection ; Cerebellum ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 1. The areas of the cerebellar cortex receiving fibres from the mLRN (major portion of the lateral reticular nucleus comprising its parvi- and magnocellular parts) were determined by identifying the low-threshold spots on the cerebellar surface from which 286 mLRN neurones could be antidromically activated. 2. The mLRN fibres terminate bilaterally in the anterior lobe and pyramis, and ipsilaterally in the paramedian lobule. Some fibres terminate also in the rostral part of lobule VI but hardly any in other parts of the cortex. It follows that the mLRN projects almost exclusively to the classical spinal receiving areas. 3. Neurones in the parvi- and magnocellular parts project to similar cortical areas. 4. Two regions in the mLRN were distinguished on the basis of their different projection areas. Region A, a dorsolateral portion of the magnocellular part, projects to the ipsilateral parts intermedia of the anterior lobe and the ipsilateral paramedian lobule. Region B, a ventral portion of the parvi- and magnocellular parts, projects bilaterally to the pars intermedia and vermis of the anterior lobe and sparsely to the pyramis. 5. Neurones throughout the parvi- and magnocellular parts receive monosynaptic excitation from fibres ascending in the ventral part of the ipsilateral lateral funiculus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00237166
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  • 11
    Electronic Resource
    Electronic Resource
    Vertical organization in the visual cortex (area 17) in the cat (1974)
    Springer
    Experimental brain research 21 (1974), S. 315-336 
    Details
    ISSN: 1432-1106
    Keywords: Visual cortex (area 17) ; Cat ; Columnar organization ; Retino-cortical scatter ; Intracortical connections
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 1. Responses of cortical cells in the cat's area 17 (central and paracentral area), recorded successively during electrode penetrations perpendicular to the surface, were averaged (PSTH). All cells recorded during one penetration were stimulated with the same stimulus, a slowly moving light or dark slit oriented optimally for the first cell recorded. Comparisons between successively recorded cells were completed by simultaneous recordings from two neurones with the same microelectrode tip. Eye movements as an error were excluded by simultaneous recording of a geniculate cell throughout a cortical penetration. 2. The centers of excitatory receptive fields (ERFs) of simultaneously or successively recorded cells during a penetration may be separated by more than 4°. The mean scatter around a column average is 0.81±0.99° in both directions. The scatter is independent of the recording depth. Whereas the optimal orientation of cells recorded during one penetration was generally similar, the optimal direction (forward and backward movement of an optimally oriented stimulus) was variable. 3. The ERF diameters as determined from the PSTH were between 〈0.5° and 7.5°. During each penetration, cells with small (up to 3.0°) and large (〉3.0°) ERFs could be discriminated. The inhibitory fields (determined with the conditioning method of Bishop, Coombs and Henry, 1971) were between 2.0 and 8.5° along both the optimal and the non-optimal orientation axis of a cell. The borders of inhibitory fields of cells collected during one penetration were also scattered though overlapping. 4. Response analysis of simultaneously and successively recorded cells with different stimuli indicated that, in spite of considerable ERF-overlap, cells with small ERFs had separate excitatory inputs and that intracortical excitatory connections between cells recorded during one penetration were improbable. 5. The ERFs of cells with large ERFs covered a field approximately corresponding to the fields of cells with small ERFs. But a convergent input from many small ERF cells to single large ERF cells was excluded because of the incompatible functional properties of both types of cells, which correspond to some extent to simple and complex cells respectively. 6. It is concluded that cells within cortical cylinders are not connected through excitatory contacts with each other and that most cells in area 17 are excited by individual excitatory geniculate or cortical inputs. Inhibitory connections seem to be the most important intracortical connections. 7. In an Appendix it is shown that anatomical and physiological data do not support significant excitatory convergence of specific geniculate afferents on cortical neurones.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00235750
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  • 12
    Electronic Resource
    Electronic Resource
    Influence of flupenthixol and flupenthixol-decanoate on methylphenidate and apomorphine-induced compulsive gnawing in mice (1974)
    Springer
    Psychopharmacology 34 (1974), S. 119-126 
    Details
    ISSN: 1432-2072
    Keywords: Psychopharmacology ; Flupenthixol ; Flupenthixol-Decanoate ; Mice ; Methylphenidate ; Apomorphine ; Compulsive Behaviour
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract α-Flupenthixol and α-flupenthixol decanoate were tested in mice against methylphenidate-induced stereotyped gnaw-compulsions. The effect of both α-flupenthixol, and α-flupenthixol decanoate disappeared 2 days after administration. In addition, the influence of α-flupenthixol and α-flupenthixol decanoate on the apomorphine-induced behaviour in mice was followed over a period of 12 days. Under these conditions apomorphine-induced compulsive gnawing was seen on the days on which the methylphenidate antagonistic effect had subsided. The apomorphine-induced compulsive gnawing seen in α-flupenthixol and α-flupenthixol decanoate pretreated animals could be antagonized by additional small doses of α-flupenthixol given 2 h before apomorphine. The interference of the neuroleptic drugs with dopaminergic receptors is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00421936
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  • 13
    Electronic Resource
    Electronic Resource
    Flunitrazepam (Ro 5-4200) and sleep cycle in insomniac patients (1974)
    Springer
    Psychopharmacology 35 (1974), S. 371-379 
    Details
    ISSN: 1432-2072
    Keywords: Psychopharmacology ; Sleep ; Insomnia ; Flunitrazepam ; Benzodiazepine ; Hypnotic
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The action of flunitrazepam (Ro 5-4200), a benzodiazepine derivative, was assessed on the sleep cycle of insomniac patients by means of all-night reeordings. Baseline placebo nights were compared with the drug (2–8 mg p.o.) and with the placebo post-drug nights. Flunitrazepam induced a shift to faster frequencies of the EEG and a disappearance of sleep stages 3 and 4 while stage 2 was increased. In 10 out of 12 studied insomniacs the compound was effective in inducing and maintaining sleep (decrease in NREM sleep latency, wake time and number of wakes) throughout the drug administration period. Both NREM and REM sleep were increased, the latter most likely in relation to a blockade of processes precluding NREM emergence. The hypnotic action of flunitrazepam was still present during the first withdrawal night, pointing out to a carry over effect.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00429228
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  • 14
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    Electronic Resource
    Effects of chlordiazepoxide on heart rate and behavioural suppression in pigs subjected to operant conditioning procedures (1974)
    Springer
    Psychopharmacology 37 (1974), S. 169-177 
    Details
    ISSN: 1432-2072
    Keywords: Pigs ; Conflict Behaviour ; Non-Reinforcement ; Chlordiazepoxide ; Psychopharmacology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Two groups of four pigs were subjected to a punishment discrimination (conflict) or to a non-reinforcement procedure. Conflict behaviour was evidenced by the suppression of operant responding and the occurrence of a marked decrease in heart rate during the presentation of the conditioned stimulus. Pigs in the non-reinforcement procedure showed no consistent changes in heart rate although an important decrease occurred in response rate. Chlordiazepoxide was administered in order to establish whether it would attenuate the response suppression in either procedure. The drug produced a weak attenuation of conflict in terms of the operant and heart rate responses at the maximum dose used (20 mg/kg) and a small disinhibiting effect on the non-reinforced responding at 10 mg/kg. Such effects were less clear-cut than usually reported in other species.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00437423
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  • 15
    Electronic Resource
    Electronic Resource
    The projection of the superior colliculus onto the reticular formation of the brain stem an experimental anatomical study in the cat (1974)
    Springer
    Experimental brain research 19 (1974), S. 1-19 
    Details
    ISSN: 1432-1106
    Keywords: Reticular formation ; Superior colliculus ; Cat ; Experimental anatomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Following altogether 18 stereotactically placed lesions of different location and size in the superior colliculus the efferent fibres to the RF and their distribution were traced in silver impregnated, approximately serial sections (Nauta and Fink and Heimer methods), cut in the transverse, horizontal or sagittal plane. The projection to the mesencephalic RF was found to be almost completely ipsilateral, that to the pontomedullary RF largely contralateral. In the mesencephalic RF the fibres end in its dorsal half approximately. In the pons and medulla they supply only the medial 2/3 of the main RF, with two distinct maxima within the total field of termination. One maximum covers the rostral part of the nucleus reticularis gigantocellularis and the adjoining part of the nucleus reticularis pontis caudalis, the other occupies the rostralmost part of the latter and the caudal part of the nucleus reticularis pontis oralis. Of the precerebellar reticular nuclei the contralateral nucleus reticularis tegmenti pontis receives a distinct component of tectal fibres in a small area dorsomedially. Some fibres end in a restricted part of the nucleus reticularis lateralis and in the paramedian reticular nucleus. The tectoreticular projection appears to be organized according to the same principles as other afferents to the RF. In the main RF the areas of termination of the tectoreticular fibres coincide more or less with the areas of termination of corticoreticular, fastigioreticular and vestibuloreticular fibres. These common terminal areas are those which give off the bulk of reticulospinal fibres. Some functional implications of the pattern of organization in the tectoreticular projection are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00233392
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  • 16
    Electronic Resource
    Electronic Resource
    Neuronal activity during eye movements in a visual association area of cat cerebral cortex (1974)
    Springer
    Experimental brain research 19 (1974), S. 467-477 
    Details
    ISSN: 1432-1106
    Keywords: Suprasylvian gyrus ; Cat ; Single neurons ; Eye movements ; Direction sensitivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 270 single neurons from the anterior part of the middle suprasylvian gyrus (AMSS) were recorded in awake and non-paralyzed cats (Chronic preparation). 10% were unresponsive to visual stimulation, the remainder reacted well to moving visual stimuli. Half of the units tested were directionally selective. Horizontal, or downward preferred directions predominated. Most neurons were relative insensitive to changes of shape, orientation, contrast, and velocity of the visual stimulus. Some neurons preferred rapid (100°/sec) jerky movements, others required complex motions of irregular shapes, a few strongly preferred objects moving towards the animal in the midsagittal plane. 40% of neurons yielded phasic On-Off reaction to flashing stationary spots. Habituation to repeated stimulation was a common feature and occured in 50% of AMSS neurons. In 19% of neurons tested the discharge rate was not affected by saccadic eye movements, when the animal faced a patterned background. Among the remainder two types of saccade associated responses could be distinguished. Type I discharged prior to or simultaneously with the onset of saccades. This early response was usually associated with saccades of particular directions. Saccades in total darkness yielded weaker and less consistent responses. Type II discharged subsequent to the onset of the saccades after a latency of 40 msec (type IIa), 40–80 msec (type IIb) and 80 msec (type IIc). Responses of type IIa are probably consequences of the retinal effects of eye movements. The saccade associated responses of type Ia, IIb and IIc are tentatively interpreted as results of an eye movement-synchroneous subcortical input, which facilitates transmission in AMSS neurons. Presaccadic facilitation, which generates type Ia responses, may be functionally related to shifts of attention prior to eye movements. It is suggested that postsaccadic facilitation, which underlies the reactions of type IIb and IIc, may be a correlate of visual attention during the fixation period.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00236111
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  • 17
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    Electronic Resource
    The organization of projections from the cerebellar nuclei to the contralateral motor cortex in the cat (1974)
    Springer
    Experimental brain research 19 (1974), S. 36-60 
    Details
    ISSN: 1432-1106
    Keywords: Cerebellar nuclei ; Motor cortex ; Evoked potentials ; Topographical organization ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 1. A topographical study of cerebello-cortical relations was conducted in cats anesthetized with chloralose. The potentials evoked by punctate stimulation of the cerebellar nuclei were recorded at various sites in the contralateral motor cortex. A map of the cortical responses obtained by stimulating each of the cerebellar nuclei was established. For this purpose, the stimulation thresholds as well as the response amplitudes, polarity and latency were noted. 2. Local stimulation of each cerebellar nucleus evoked responses in particular regions of the contralateral motor cortex. When a stimulus was applied to the interpositus nucleus, short latency responses were recorded in the lateral part of the area 4. Dentate nucleus stimulation induced short latency responses in the medial part of area 4 and in area 6. Furthermore, late responses were also recorded laterally in area 4. 3. The interpositus nucleus was found to project to the portion of motor cortical area controlling the distal forelimb with only a fast conducting pathway. The fastigial nucleus seems to be connected with proximal and axial motor areas. The projection system of the dentate nucleus appears to have a temporal organization: a fast conducting pathway was found to project to the axial and proximal motor area while a slower one seems to transmit impulses to the motor area of the forelimb extremity. 4. The functional aspects suggested by the temporal organization of the cerebellocortical inputs and the distribution of each nucleus projections on the motor cortical areas are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00233394
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  • 18
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    Electronic Resource
    Lack of fixed order of recruitment in cat motoneuron pools (1974)
    Springer
    Experimental brain research 20 (1974), S. 101-114 
    Details
    ISSN: 1432-1106
    Keywords: Size principle ; Motoneurons ; Cat ; Recruitment ; Neurophysiology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Henneman et al. have shown that a wide variety of stimuli activate motoneurons in the order of their sizes, though some reversals occur. It is not clear which motoneurons should be included in the “pool” from which recruitment by size takes place. The “pool” may consist of 1. all the motoneurons to a given muscle 2. all the motoneurons in a given ventral root or 3. all the motoneurons activated by a given stimulus. We have examined recruitment in the pool of fibers to a given muscle. A variety of mechanical stimuli to cat's legs were used to elicit bursts of activity in gastrocnemius motor units. In 30% of pairs of units, one unit had a consistently lower threshold, i.e. it always began and ended a burst. In the other 70%, either unit could start or end a burst. For 48% of motor unit pairs recorded in either the medial or lateral gastrocnemius, each unit of the pair had runs of firing of at least 10 spikes while the other was totally inactive. By the same criterion, 23% of pairs of temporalis units showed differential activity. During spontaneous breathing there was no consistent recruitment order in 24% of pairs of units in throat respiratory muscles. These data indicate that reversals of recruitment order are relatively common for motoneurons innervating the same muscle. We discuss the possibility that size principle may hold for motoneurons in a single ventral rootlet whose somas are anatomical neighbors (even though they innervate different muscles), but not for motoneurons that are anatomically distant in the cord (even though they innervate the same muscle).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00234005
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  • 19
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    Electronic Resource
    Effect of differential blocking of motor axons on antidromic activation of Renshaw cells in the cat (1974)
    Springer
    Experimental brain research 20 (1974), S. 135-143 
    Details
    ISSN: 1432-1106
    Keywords: Cat ; Renshaw cell ; Antidromic activation ; Differential blocking
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Attempts were made to study differences in the relative effectiveness of different size ranges of motor axons to Renshaw cells by differential blocking of larger fibers of the gastrocnemius nerve in cats anesthetized with Nembutal. 1. Differential blocking of larger fibers in the nerve was successfully obtained by applying trapezoid wave current to the nerve. 2. It was shown that more than half (58.1%) of the Renshaw cells receive homogeneous inputs from a motor axon collaterals, 25.8% of the cell receive collateral inputs from a certain group of fibers, and 12.5% of the Renshaw cells were activated by “γ range” fibers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00234008
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  • 20
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    Electronic Resource
    Reflexes in postganglionic fibres within skin and muscle nerves after mechanical non-noxious stimulation of skin (1974)
    Springer
    Experimental brain research 20 (1974), S. 115-123 
    Details
    ISSN: 1432-1106
    Keywords: Somato-sympathetic reflexes ; Postganglionic fibres to skin and muscle ; Natural stimulation of skin ; Hair-follicle receptors ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 1. Somato-sympathetic reflexes in postganglionic neurones to hairy skin and to muscle produced by mechanical non-noxious stimulation of skin were studied in cats anesthetized with chloralose. Most of the postganglionic fibres investigated were spontaneously active and had presumably vasoconstrictor function. 2. In 60% of the cutaneous postganglionic neurones stimulation of hairs induced predominantly excitation. This excitation was mostly followed by a slight depression of the spontaneous activity. In 30% of the neurones the spontaneous activity was depressed or predominantly depressed by these stimuli. 3. In most muscle postganglionic neurones the spontaneous activity was depressed by stimulation of hairs. 4. In both types of neurones the reflexes were produced by activity in hair follicle receptors with Group II afferents. Hair follicle receptors with Group III afferents most probably also contributed to this effect. Except for a slight depression of the spontaneous activity in some cutaneous postganglionic neurones by slowly adapting receptors, mechanical stimulation of other types of receptors with Group II afferents had no effect on the postganglionic neurones. 5. Reflexes in postganglionic neurones could be elicited by stimulation of hairy skin all over the body surfaces.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00234006
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  • 21
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    Electronic Resource
    Projections thalamiques des noyaux vestibulaires: Etude histologique chez le chat (1974)
    Springer
    Experimental brain research 20 (1974), S. 273-283 
    Details
    ISSN: 1432-1106
    Keywords: Vestibular nuclei ; Thalamic projections ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Electrolytic lesions were placed into the left vestibular nuclei of 22 adult cats. Silver impregnation for degenerated terminal fibres of serial sections revealed the existence of a relay of the corticopetal vestibular pathway in the contralateral thalamus. Its main afferent fibres originate in the superior and medial vestibular nuclei. By crosschecking the results it was possible to demarcate a focus of vestibular projections in the ventro-caudal part of the thalamus, situated between the centre median, the ventro-basal group and the caudal segment of the ventro-lateral nucleus. The direct ascending afferents of this focus are relatively few in number. The functional significance of this vestibular relay with regard to the proprioceptive influx passing through this region of the thalamus is open to discussion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00238317
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  • 22
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    Electronic Resource
    Bilateral semicircular canal inputs to neurons in cat vestibular nuclei (1974)
    Springer
    Experimental brain research 20 (1974), S. 285-296 
    Details
    ISSN: 1432-1106
    Keywords: Ampullary nerve ; Cat ; EPSP ; IPSP ; Vestibular neuron
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The six ampullary nerves in both labyrinths were separately stimulated by electric pulses in anesthetized cats. Resulting responses in neurons in the vestibular nuclei were recorded intracellularly. Almost all the vestibular neurons showed an EPSP in response to stimulation of the ipsilateral ampullary nerve. These neurons were subclassified as A-, L-, and P-neuron receiving specific projections from the anterior, lateral and posterior canal, respectively. Three fourths of the vestibular neurons recorded from received an IPSP in response to stimulation of the contralateral ampullary nerve. Plane-specific contralateral inhibition was found in most of vestibular neurons; i.e. A-, L-, and P-neuron received IPSP from the contralateral posterior, lateral, and anterior ampullary nerve, respectively. Approximately two thirds of vestibular neurons exhibiting the plane-specific inhibition were recorded in the medial vestibular nucleus. A collision test of impulses in primary afferent fibers were performed during recording of ipsilateral EPSPs produced by strong stimulation of more than one ampullary nerve. No positive evidence was provided for the existence of neural convergence on single vestibular neurons from different ampullary nerves on the same side. It is suggested that the plane-specific contralateral inhibition increase the sensitivity of vestibular neurons during head rotation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00238318
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  • 23
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    Electronic Resource
    Responses of cat vestibular neurons to sinusoidal roll tilt (1974)
    Springer
    Experimental brain research 20 (1974), S. 347-362 
    Details
    ISSN: 1432-1106
    Keywords: Vestibular nuclei ; Tilt response ; Sinusoid ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Extracellular recordings were made in the lateral and inferior vestibular nuclei of decerebrate, unanesthetized cats. The firing patterns of single units were studied using small amplitude sinusoidal roll tilts of from 0.01 Hz to 1.0 Hz. Three-fourths of the tilt-sensitive units showed greater modulation of their firing rates as the frequency of the sinusoidal tilt was increased. The responses of cells in both nuclei were similar. These responses were virtually unchanged in cats with chronically plugged semicircular canals, indicating a probable otolith origin for the dynamics of the tilt response.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00237380
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  • 24
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    Electronic Resource
    Somatosensory cortical involvement in responses to noxious stimulation in the cat (1974)
    Springer
    Experimental brain research 20 (1974), S. 363-374 
    Details
    ISSN: 1432-1106
    Keywords: Pain ; Somatosensation ; Cerebral cortex ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The experiment examines the role of the cerebral cortex in regulating responses to noxious stimulation by studying the effects of cortical ablations in cats on escape from electric shock applied to the foot pads. The latency of escape as a function of shock intensity was measured before and after bilateral ablations of various portions of the cat's somatosensory cerebral cortex. Ablations of the second somatosensory cerebral cortex significantly increased the escape response threshold. If the sulci bordering this region were included in the ablation, the threshold increase was greater and longer-lasting. Ablations of the primary somatosensory cortex increased latencies at most intensities of electric shock, but did not change the response thresholds. Ablations of both primary and second somatosensory cortex increased response thresholds and response latencies. None of these ablations altered the responses, however, if the cat had been overtrained for six to seven months prior to surgery. The results suggest that the second somatosensory region and the sulci bordering the second somatosensory region in the cat cerebral cortex are involved in responses to noxious stimulation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00237381
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  • 25
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    Electronic Resource
    An intracellular study of neuronal organization in the visual cortex (1974)
    Springer
    Experimental brain research 21 (1974), S. 45-66 
    Details
    ISSN: 1432-1106
    Keywords: Visual cortex ; Efferent cells ; Non-efferent cells ; Synaptic connection ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Neuronal connections in the visual cortex of cat (areas 17 and 18) were studied with intracellular recording and electrical stimulation techniques under Nembutal anaesthesia. Four types of axonal projection were seen; 1. association efferent cells projecting to adjacent cerebral cortex on the ipsilateral side, 2. commissural efferent cells to visual cortex on the contralateral side, 3. corticofugal efferent cells to the ipsilateral lateral geniculate body and superior colliculus, and 4. non-efferent cells whose projection is confined within the visual cortex. Both association and commissural efferent cells were located in layer III, corticofugal efferent cells in layer V and non-efferent cells in layers II–VI. Upon these cells two types of synaptic actions were exerted by the specific visual afferents that originate from the lateral geniculate body; 1. type I, monosynaptic excitation plus disynaptic inhibition and 2. type II, disynaptic excitation plus trisynaptic inhibition. Type I effects were found in layers III–V, and type II in layers II and VI. In the border region between areas 17 and 18 monosynaptic excitation and disynaptic inhibition were produced also by the commissural efferents originating from the contralateral visual cortex. On the basis of these results, a possible neuronal circuitry in the visual cortex is postulated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00234257
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  • 26
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    Electronic Resource
    The lateral reticular nucleus in the cat III. Organization of component activated from ipsilateral forelimb tract (1974)
    Springer
    Experimental brain research 21 (1974), S. 501-513 
    Details
    ISSN: 1432-1106
    Keywords: Lateral reticular nucleus ; Spinoreticular tract ; Cerebellum ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 1. The activation of neurones in the mLRN (major portion of lateral reticular nucleus comprising its parvi- and magnocellular parts) by two spinal tracts ascending through the ventral part of the lateral funiculus has been studied by recording from 277 neurones of which 187 could be antidromically activated by stimulation of the cerebellar surface. Forty-eight % of the neurones were activated by the bVFRT and described in a previous paper (Clendenin et al., 1975b) and 12% were activated by a previously unknown tract denoted the ipsilateral forelimb (iF) tract and described in the present paper. 2. The iF-tract is activated by stimulation of nerves in the ipsilateral forelimb only. The response consists of a train of impulses with a high initial frequency and an almost constant latency. Cutaneous afferents and high threshold muscle afferents contribute to the excitation which is mediated by interneurones. 3. The responses to stimulation of peripheral receptors were weak and difficult to classify. 4. The iF-tract activates neurones in the dorsolateral portion of the magnocellular part of the mLRN which projects to the ipsilateral pars intermedia of the anterior lobe and the ipsilateral paramedian lobule. 5. The possible information carried by the iF-tract is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00237168
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  • 27
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    Electronic Resource
    On the origin of the corticotectal projections in the cat (1974)
    Springer
    Experimental brain research 21 (1974), S. 433-439 
    Details
    ISSN: 1432-1106
    Keywords: Superior colliculus ; Visual cortex ; Layer V-pyramids ; Clare Bishop area ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Stereotaxic injection of horseradish peroxidase into the superior colliculus produced retrograde labelling of layer V pyramides in the Clare Bishop area and the lateral bank of the suprasylvian sulcus, in area 17,18 and 19. Single labelled cells were also found scattered in the splenial, the suprasplenial, the lateral and the suprasylvian gyri. In the cruciate sulcus no labelled cells were observed. Autoradiographically, the lateral bank of the suprasylvian sulcus was also shown to give rise to fibres to the superior colliculus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00237905
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  • 28
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    Electronic Resource
    The lateral reticular nucleus in the cat II. Organization of component activated from bilateral ventral flexor reflex tract (bVFRT) (1974)
    Springer
    Experimental brain research 21 (1974), S. 487-500 
    Details
    ISSN: 1432-1106
    Keywords: Lateral reticular nucleus ; Bilateral ventral flexor reflex tract (bVFRT) ; Spino-reticulo-cerebellar path ; Cerebellum ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 1. Neurones in the lateral reticular nucleus (LRN) activated by the bilateral ventral flexor reflex tract (bVFRT-LRN neurones) were identified by their responses to stimulation of fibres descending in the contralateral ventral quadrant of the spinal cord which activate the bVFRT neurones monosynaptically. 2. Eighty-eight of the 134 bVFRT-LRN neurones encountered could be antidromically activated at a low stimulus strength from small areas of the cerebellar surface assumed to represent cortical termination points. 3. The bVFRT-LRN neurones occurred throughout the parvi- and magnocellular parts of the LRN and terminated bilaterally in the anterior lobe and sparsely in the ipsilateral paramedian lobule and in the pyramis. 4. The responses evoked in the bVFRT-LRN neurones on stimulation of the contralateral ventral quadrant at C5 and L1 made it possible to estimate the approximate spinal level from which the bVFRT fibres originated. On this basis the bVFRT-LRN neurones were divided into cervical, thoracic, and lumbar groups receiving bVFRT afferents from mainly one spinal level and a convergence group receiving bVFRT afferents from several levels. 5. The different bVFRT-LRN groups received excitation from different combinations of nerves in the four limbs. 6. The cervical, thoracic and lumbar groups of the bVFRT-LRN neurones occurred in successively more ventrolateral portions of the LRN. 7. The cervical, thoracic and lumbar groups of the bVFRT-LRN neurones terminated in successively more rostral areas of the anterior lobe. 8. The organization of the bVFRT-LRN path is compared with that of the ventral and rostral spinocerebellar tracts. The possible function of the bVFRT-LRN path is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00237167
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  • 29
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    Effets de la stimulation des fibres et des mécanorécepteurs splanchniques sur l'activité unitaire du cortex somesthésique (1974)
    Springer
    Pflügers Archiv 348 (1974), S. 127-137 
    Details
    ISSN: 1432-2013
    Keywords: Splanchnic Afferents ; G.I. and Peritoneal Receptors ; Cortical Projections ; Microelectrode Technique ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The experiments were performed on cats anesthetized with chloralose or Nembutal. The unitary activity of cortical neurons was recorded in the SI and SII areas by means of extracellular glass microelectrodes. The neurons showed frequently a spontaneous discharge (irregular or regular tonic discharge bursts of spikes). The electrical stimulation of contralateral splanchnic nerves produced different effects on a great number of the neurons: 1. early short activation, 2. late activation, 3. early and late complex activation, 4. partial or total inhibition of the spontaneous activity. These effects were obtained in the different cortical layers. Similar results have been observed by mechanical stimulation of the splanchnic receptors located in the gastro-intestinal tract and in the peritoneum. However in this case, the duration and the amplitude of inhibition and activation were generally weaker.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00586475
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  • 30
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    Electronic Resource
    Junctions in the central nervous system of the cat (1974)
    Springer
    Cell & tissue research 148 (1974), S. 577-586 
    Details
    ISSN: 1432-0878
    Keywords: Node of Ranvier ; Axonal-glial junctions ; Cat ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The paranodal zone of myelinated nerve fibers from the CNS of cats has been studied by means of the lanthanum technique and after freeze-etching. Special interest was given to the axonal-glial zones of contact in this region. Examination of the membranes of the paranodal pockets and the axolemma revealed that the membrane thickenings which occur between the adjacent membranes actually consist of bands. The bands show a specific pattern of diagonal running subunits 10 nm apart. These substructures of the axonal side of the membrane contacts protrude outwards, i.e. towards the glial membrane, where they fit into depressions on the glial membrane surface. This arrangement in form of a “zip-fastener” makes the whole structure very flexible. The subdivision of the bands was identified with both techniques. The different membrane aspects obtained by the freeze-etching technique are discussed in respect to the splitting theory, and a hypothetical model of this membrane specialization is presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00221941
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  • 31
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    Electronic Resource
    Electron microscopic investigation of synaptic organization of the trochlear nucleus in cat (1974)
    Springer
    Cell & tissue research 150 (1974), S. 409-423 
    Details
    ISSN: 1432-0878
    Keywords: Synaptic organization ; Trochlear nucleus ; Cat ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Two distinct types of neuron in the cat trochlear nucleus (one large, one small) are described, the α- and γ-motoneurons, respectively. Four types of terminals are observed which establish axo-dendritic synapses. Two of them (Types I and II) perform axo-somatic synapses as well. Terminals en passant (Types I and II) are predominant. The Type I terminal is long and slender with a characteristic distribution of the axoplasmic organelles and the unique feature of a relative narrowing of the synaptic cleft as compared to the width of the neighboring extracellular space. Its vesicle population is pleomorphic and a conspicuous glial barrier surrounds the synaptic zones. The Type II terminal differs slightly from Type I, revealing a wider synaptic cleft and lacking a characteristic distribution of the axoplasmic organelles. The type III terminal is rarely observed performing axo-somatic synapses, but is a common finding in the neuropil. Post-junctional dense bodies are often present in its axodendritic synapses. The Type IV nerve terminal performs axo-dendritic synapses and is characterized by a rich content of large granulated vesicles. Axo-axonal synapses are observed only very rarely. The synaptic organization of the feline trochlear nucleus is compared with the synaptic morphology of the oculomotor nuclei of inframammalian species (Waxman and Pappas, 1971). In addition to certain similarities (e.g., richness of synapses en passant), significant differences are encountered: the present study provides no morphological evidence for electrotonic transmission in the trochlear nucleus of cat.
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    URL: http://dx.doi.org/10.1007/BF00220147
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  • 32
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    Some observations on the ultrastructure of the central amygdaloid nucleus in the cat (1974)
    Springer
    Cell & tissue research 151 (1974), S. 489-498 
    Details
    ISSN: 1432-0878
    Keywords: Limbic system ; Cat ; Amygdaloid body ; Light and electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The present study was undertaken to re-examine the central nucleus of the cat in Nissl stained sections, to describe its fine structural characteristics, and to compare the lateral subdivision of this nucleus with the putamen. In Nissl preparations, it was observed that the lateral subdivision of the central nucleus contains a fairly homogeneous population of small cells while the putamen contains both small and large cells. It is the presence of a few large cells at the lateral periphery of the lateral part of the central nucleus that makes the boundary between the two nuclei indistinct. Examination of the fine structure of the medial and lateral subdivisions of the central nucleus revealed the presence of many boutons containing flattened vesicles and fewer with spheroid vesicles. In contrast, most of the boutons in the putamen have spheroid vesicles. It is concluded that the lateral subdivision of the central nucleus may be distinguished from the putamen, except at its most lateral border, by its homogeneous population of small cells and its many boutons containing flattened vesicles.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00222994
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  • 33
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    Electronic Resource
    Junctions in the central nervous system of the cat (1974)
    Springer
    Cell & tissue research 149 (1974), S. 121-135 
    Details
    ISSN: 1432-0878
    Keywords: Astrocytic membranes ; Cat ; Orthogonal particle-complexes ; Freeze-etching
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Fixed and unfixed astrocytic membranes from the CNS of the cat were studied by means of the freeze-etching technique. A variable number of gap junctions was detected in astrocytic membranes. They are characterized by the well known hexagonal composition of their subunits. Besides this type of highly ordered membrane-bound particles, a second one was found. It is composed of four single particles (diameter 5 nm) which form an orthogonal subunit with a side length of about 10 nm. These membrane-associated orthogonal particle complexes (MOPC) could be observed in different stages of aggregation and expansion. They reveal an accumulation in membranes of the marginal glia layers and in the perivascular astrocytic end-feet. Unfixed, glycerol treated membranes, however, do not show these structures. After glycerol treatment of the unfixed membranes by immersion, the MOPC disintegrate to single particles which form clusters of various extension. The clustering phenomenon is dependent on the length of the time of exposure to glycerol. Shortening of the glycerol treatment by intravasal perfusion of the cryoprotectant agent causes an decrease of the clusters. Fragments and transient forms of the MOPC become visible. By variation of different physico-chemical parameters of the washing solution a similar effect on the MOPC was not achieved. The discussion deals with probable functional aspects of the MOPC. They are considered to act as membrane-bound functional multienzyme complexes which a) might play a role in mediating transmembrane passage of metabolites, or b) are essential for CSF control mechanisms, or c) have a functional relation to the nexus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00209055
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  • 34
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    Electronic Resource
    Nerve endings in the arteria centralis retinae (1974)
    Springer
    Cell & tissue research 150 (1974), S. 143-145 
    Details
    ISSN: 1432-0878
    Keywords: Arteria centralis retinae ; Cat ; Innervation ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Terminal axons emerging from the inner plexiform layer of the cat retina reach the wall of the arteria centralis retinae, as revealed by electron microscopy. Numerous unusually large dense core vesicles (about 1000 Å in diameter), of different electron densities, occur in the varicosities of these axons. These observations may be compatible with the idea of an innervation of the central artery of the retina which is non-autonomic, possibly intrinsic in nature.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00220387
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    Electronic Resource
    Junctions in the central nervous system of the cat (1974)
    Springer
    Cell & tissue research 148 (1974), S. 565-576 
    Details
    ISSN: 1432-0878
    Keywords: Central myelin ; Junctions ; Cat ; Freeze-etching ; Lanthanum impregnation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In male and female cats central myelin was studied using the freeze-etching technique, and after impregnation with lanthanum as a tracer. The freeze-fractured and etched faces of the myelin reveal membrane formations which in many respects resemble tight junctions. The formations consist of parallel rows of particles on one half of the membranes matched by corresponding furrows on the other membrane half. These structures occur across the width of the myelin sheath and are most common in that part of the myelin underlying the external cytoplasmic loop. They are interpreted as correlates of the radial component of the i-line which occurs in cross-sections of central myelin after potassium permanganate staining. In the paranodal zone the lanthanum-impregnated myelin displays punctate fusions between the outer leaflets of the oligodendrocytic membranes. These findings strongly suggest that tight junctions are a common feature in the central myelin. The arrangement of the membrane fusion in relation to the elements of the lamellar complex and their functional significance is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00221940
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    Electronic Resource
    Electronic Resource
    Hypothalamic projections to the amygdala in the cat (1974)
    Springer
    Cell & tissue research 151 (1974), S. 499-508 
    Details
    ISSN: 1432-0878
    Keywords: Limbic system ; Cat ; Amygdaloid body ; Hypothalamus ; Stereotaxic lesions ; Light and electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In order to determine the origin of the hypothalamo-amygdaloid connections in the cat, small lesions were placed at various rostro-caudal levels of the hypothalamus. The animals were sacrificed after a period of 4, 8 or 11 days and the brains stained with the Nauta (1957), Fink and Heimer (1967) or Wiitanen (1969) method for the demonstration of degenerating axons and their terminals. It was observed that the anterior hypothalamic nucleus sends a small projection to the medial subdivision of the central nucleus and to the basal and lateral nuclei of the amygdala. The lateral preoptic area sends a larger projection to the anterior amygdaloid area, both subdivisions of the central and basal nuclei, and to the lateral and medial nuclei. No degeneration was observed in the amygdala following lesions in the medial preoptic area, the ventromedial nucleus or the lateral hypothalamic area caudal to the anterior hypothalamic area. In a series of animals with lateral preoptic lesions, the site of termination of degenerating boutons on neurons of the amygdaloid nuclei was determined and the course of the degenerative process followed over a period ranging from 2 to 15 days. Many of the boutons, especially in the earlier stages of degeneration, appeared to be of the B3 type, containing flattened vesicles and forming symmetrical synaptic contacts with dendrites or somata. With longer post-operative survival times, however, they became increasingly electron dense and shrunken, so that the bouton type could not be determined.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00222995
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    Morphology of siloxane block copolymers: Tetramethyl-p-silphenylene siloxane-dimethylsiloxane (1974)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 12 (1974), S. 317-333 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The morphological features of random block copolymers of tetramethyl-p-silphenylene (TMPS) and dimethylsiloxane (DMS) have been studied as a function of copolymer composition. Wide-angle and small-angle x-ray diffraction coupled with several electron diffraction and microscopy studies were used to investigate these materials. The results of this work clearly indicate that the amorphous segments do not enter into the crystalline lattice of the crystallizable component which is varied in content from 90% to 30%. Over the entire range of compositions the block copolymers are crystallizable. Spherulites can be grown from the melt, and single crystals and/or spherulites may be obtained from solution. Single crystals can be obtained over the entire range of compositions provided ample time is allowed for crystallization. The crystalline TMPS component exhibits tetragonal symmetry at all compositions. The amorphous phase manifests itself as a diffuse halo in patterns obtained by electron and x-ray diffraction.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1974.180120208
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    Crystallization of poly(ethylene terephthalate) induced by inorganic compounds. I. Crystallization behavior from the glassy state in a low-temperature regionThis paper was presented in part at the IUPAC Symposium on Macromolecules in Leiden, 1970. (1974)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 12 (1974), S. 303-316 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The kinetics of isothermal crystallization from the glassy state at low temperatures and the morphology of poly(ethylene terephthalate) (PET) filled with additives are reported. Talc, kaolin, silicon oxide, and titanium oxide have been used as fillers; they act as effective nucleating agents for PET. The overall rate of crystallization depends on the volume concentration, the size distribution, and the nucleating ability of the additives. An electron microscopic study reveals a transcrystalline morphology at the surface of the filler particles. The occurrence of transcrystallinity is attributed to extensive heterogeneous nucleation induced at the filler surface. From the shape of the crystallization isotherms, it can be concluded that the crystallization mechanism depends on the type of filler.
    Additional Material: 9 Ill.
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    URL: http://dx.doi.org/10.1002/pol.1974.180120207
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    Electronic Resource
    Electronic Resource
    Theory of phase transition kinetics with growth site impingement. I. Homogeneous nucleation (1974)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 12 (1974), S. 399-406 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The nonlinear integral equations governing phase transition kinetics with homogeneous nucleation and growth site impingement are developed and solved to the first order for the two-dimensional case. It is shown that the fractional transformed area at time t is given approximately by a(t) = Kt3/(1 + Kt3). The iteration method used to get the solution is applicable to certain other nonlinear differential and integral equations. It is shown that the theory predicts the total number of growth sites formed, and that the nucleation rate and growth constants can be deduced from this and the gross kinetic data. The extension of the method of three-dimensional growth is indicated.
    Additional Material: 1 Tab.
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    URL: http://dx.doi.org/10.1002/pol.1974.180120212
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    Electronic Resource
    Excluded-volume effect for various chain models. I. Application to optical anisotropy and end-to-end distance of linear polymers (1974)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 12 (1974), S. 417-429 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A study of the effect of excluded volume on the mean-square optical anisotropy 〈γ2〉 and the mean-square end-to-end distance 〈R2〉 has been carried out for polymer chains of up to 2000 bonds. The calculations have been made for models assuming (a) equiprobability of internal rotations and (b) interdependence of short-range intramolecular interactions. All the results indicate that 〈γ2〉 is practically insensitive to the excluded-volume effect. Concomitantly the behavior of 〈R2〉 has been analyzed.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1974.180120214
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    Electronic Resource
    NMR spectrum of poly(vinyl chloride) (1974)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 12 (1974), S. 655-664 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The 100-MHz proton NMR spectra of commercial and laboratory-prepared poly(vinyl chloride) (PVC) have been measured in various solvents at high temperature (80-150°C). Tacticity in PVC was determined by the analysis of the β-proton spectrum. The spectrum was calculated assuming that the PVC chain consists of tetrad sequences of monomer units and that their distribution in the chain is described by a simple Bernoulli-sequence statistics with a Pm (the probability of isotactic placement) of 0.45 for commercial PVC polymerized at 50°C. Tacticity calibration curves based on measurements made for the polymer in pentachloroethane and β-dichlorobenzene were established, and they provide a simple method for the measurement of tacticity in PVC directly from the observed spectra. Excluding samples prepared in butyraldehyde solution, the formation of syndiotactic structures in PVC (prepared by free-radical polymerization) was found to be favored by lowering the polymerization temperature. This preference is due to an increase in the activation enthalpy of 510 cal/mole which is required for forming an isotactic placement in the chain during the propagation step.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/pol.1974.180120403
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    Electronic Resource
    Raman scattering in uniaxially oriented samples of planar zigzag poly(vinylidiene fluoride) (1974)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 12 (1974), S. 695-702 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Band assignments of phase-I PVF2 have been Revised by using additional data obtained by laser Raman spectra of oriented samples. A set of least-squares refined force constants was obtained which reproduce the experimental data to an average error in frequencies of 1.3 cm-1. In order to determine the effect of electrical polarization on the spectra, a Gaussian distribution of the dipole axis was assumed. The calculation shows that polarizations of less than 60% will not significantly affect the Raman spectra.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1974.180120406
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  • 43
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    Electronic Resource
    Brillouin scattering in amorphous polymeric solids (1974)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 12 (1974), S. 713-733 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Brillouin scattering of laser light has been used to study the temperature dependence of phonon velocity in a variety of amorphous polymeric systems, particularly internally and externally plasticized methacrylates. Discontinuities in the temperature coefficient of the hypersound velocities are observed at the glass transition temperatures (Tg). This phenomenon is related to changes in the temperature behavior of the specific volume accompanied by corresponding discontinuities in certain second-order thermodynamic quantities. This method was also used to examine the temperature dependence of the Landau-Placzek ratio.This ratio is relatively large in polymer systems and appears to be independent of temperature in the region of the glass transition, provided that there are no internal strains in the sample at the temperature of measurement. Evidence is presented which suggests that the abrupt changes in this ratio at Tg reported by earlier workers were due to kinetic effects related to the relaxation of internal strains above Tg, and the results of recent studies by other investigators, both corroborating and supplementing the present work, are reviewed.
    Additional Material: 11 Ill.
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    URL: http://dx.doi.org/10.1002/pol.1974.180120408
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    Electronic Resource
    Analysis of fractionation of ethylene-propylene copolymers (1974)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 12 (1974), S. 785-793 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Analysis of the solution fractionation of ethylene-propylene copolymers was carried out by assuming a bivariate normal distribution function for the distribution of molecular weight and chemical composition. It was found that the variation of the molecular weight and composition distributions in fractions was complicated, because two distribution characteristics of the original copolymer affect fractionation to differing extents. The hypothetical cumulative weight distribution curves thus obtained agreed essentially with those obtained experimentally.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1974.180120411
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    Study of the λ transition in liquid sulfur with a differential scanning calorimeter (1974)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 12 (1974), S. 815-818 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1974.180120415
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    Electronic Resource
    Solution properties of high molecular weight polystyrene (1974)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 12 (1974), S. 871-890 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A series of polystyrenes with weight-average molecular weight M̄w up to 1.3 × 107 was prepared by anionic polymerization in tetrahydrofuran (THF). Each sample was characterized by gel-permeation chromatography, light scattering, and viscometry. It was found that each sample had an almost symmetrical and very narrow molecular weight distribution (M̄w/M̄n 〈 1.07). The mean-square unperturbed radius of gyration 〈S2〉0 was determined in trans-decalin at 20.4°C as 〈S2〉0 = 7.86 × 10-18M̄w (cm2). The particle scattering factor was well represented by the Debye equation irrespective of solvent in the range of M̄w 〈 4 × 106, and only a small deviation was observed in benzene at higher molecular weights. The penetration function Ψ ≡ A2M2/4π3/2NA〈S〉23/2 was found to approach a relatively low asymptotic value of 0.21-0.23 at molecular weights above 2 × 106 in benzene at 30°C, where A2 is the second virial coefficient and NA is Avogrado's number. It was also found that the theta temperature in trans-decalin was affected by the nature of polymer samples. A difference of about 3°C in the theta temperature was observed between two series of anionic polystyrenes, one prepared in THF and the other in benzene, but there was practically no difference in unperturbed chain dimension.
    Additional Material: 15 Ill.
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    URL: http://dx.doi.org/10.1002/pol.1974.180120503
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  • 47
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    Electronic Resource
    A search for the mosaic block structure in polyethylene single crystals (1974)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 12 (1974), S. 1015-1022 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A diffraction contrast study with the aid of an image intensifier was undertaken to obtain direct evidence for the existence of a mosaic block structure in polyethylene single crystals grown by self seeding under isothermal conditions. Dark-field microscopy indicates that the crystals do not contain a mosaic block structure. High-resolution electron diffraction confirms that the crystal is coherent (i.e., mosaic block-free) over regions of several thousands of Angstroms. It is concluded that a mosaic structure on the scale of ∼300 Å does not exist in polyethylene single crystals grown under carefully controlled conditions from dilute solutions. Possible reasons for previous results that indicate the presence of a ∼300 Å mosaic block structure are discussed.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1974.180120512
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  • 48
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    Electronic Resource
    Dynamic viscosity of dilute aqueous solutions of poly(acrylic acid) at frequencies of 2-500 kHz (1974)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 12 (1974), S. 1035-1052 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The dynamic viscosity of aqueous solutions of poly(acrylic acid) at a polymer concentration of ca. 0.15 g/100 ml has been measured at frequencies from 2 to 500 kHz as a function of degree of polymerization P, degree of neutralization α, and salt (NaCl) concentration Cs. Relaxation spectra have been obtained from the dynamic viscosity. The spectra in the short relaxation time region can be approximated by the Zimm theory for the conformational relaxation of nonionic polymers. The maximum relaxation time τ1 of the Zimm spectra is proportional to P2 and depends rather moderately on α and Cs. Increased deviation is found, however, in the long relaxation time region, in particular for high values of P and α and low values of Cs. The major part of the deviation is interpreted in terms of rotational relaxation of a molecule as a whole. The rotational relaxation time τR is proportional to P3 and increases with increasing α and decreasing Cs. The remaining part of the excess spectra located between τ1 and τR is ascribed to the deviation of the conformational relaxation from the Zimm theory arising from ionization of the polymer.
    Additional Material: 18 Ill.
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    URL: http://dx.doi.org/10.1002/pol.1974.180120602
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    Electronic Resource
    Cellulose triacetate single crystals grown from solution at high temperature without inclusion of solvent (1974)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 12 (1974), S. 1117-1126 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Single crystals of cellulose triacetate II (CTA II) free of crystallization solvent can be grown from dilute solution in mixtures of dibenzyl ether and n-tetradecane. Good results are obtained by using a polymer fraction with a degree of polymerization of 60 and a mixture of 70% n-tetradecane and 30% dibenzyl ether at 245°C. The lamellar crystals produced are lozenge-shaped with the longer diagonal parallel to the a axis of the lattice and with {110} as the growth faces. Twin growth occurs frequently with {110} as a twinning plane and less frequently with {210}.
    Additional Material: 8 Ill.
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    URL: http://dx.doi.org/10.1002/pol.1974.180120607
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  • 50
    Electronic Resource
    Electronic Resource
    Electron trapping and luminescence mechanism in thermoluminescence of irradiated polycarbonate (1974)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 12 (1974), S. 1109-1115 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Thermoluminescence of polycarbonate irradiated by electron beams was observed in order to investigate the trapping of electrons and the luminescence mechanism. The thermoluminescence glow curve is composed of three components. The peaks appear at -150°C (α peak), -120°C (β peak), and -30°C (γ peak). The α peak is attributed to recombination of cations with electrons released from trapping sites formed by carbonate groups. The β peak is attributed to small amounts of impurities. The γ peak is perhaps due to untrapping of electrons from the phenoxy anion. The luminescence intensity of the α peak is linearly dependent on the absorbed dose, and that of the β peak is approximately proportional to the cube of the dose. The appearance of these peaks is presumably closely related to local molecular motions.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/pol.1974.180120606
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    An etching technique to reveal the supermolecular structure of crystalline polymers (1974)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 12 (1974), S. 1163-1175 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Highly polished surfaces of nylon 6, nylon 66, polychlorotrifluoroethylene and polypropylene were etched by aromatic and chlorinated hydrocarbons at temperatures between 25 and 75°C to reveal surface morphology. Comparison with micrographs obtained with microtomed sections shows the absence of etching artifacts which are known to accompany the use of oxidizing etching agents.
    Additional Material: 13 Ill.
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    Electronic conduction and polarization in polyphthalocyanines (1974)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 12 (1974), S. 913-924 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The polymeric hydrogen form of phthalocyanine is found to be more conductive than the metallic derivatives, in contrast to the behavior of the monomers. In addition, the polymers were found to be much more conductive than the corresponding monomers with the resistivity of the polymers ranging from 7 ohm-cm to about 3 × 106 ohm-cm. The polymers were found to have moderately high dielectric constants ranging from 16 to 1300 at room temperature, depending upon the applied pressure. Based on the dependences of the conductivity and permittivity upon the electric field strength, the average molecular length of the conductive paths within the polymer molecule has been estimated to be 100-1000 Å. In view of these estimated lengths, together with the exponential dependence of the permittivity and conductivity upon the pressure and temperature, the dispersion of the dielectric constants in the range of 10-100 KHz, and the chemical architecture of these ribbonlike polymers, the electronic behavior of these polymers is concluded to be consonant with the model of essentially one-dimensional conduction within and along the chains by freed charges. Much as in a number of previously studied highly conjugated polymers, the present polyphthalocyanines are semiconducting and exhibit nomadic polarization, with dielectric constants ranging from 70 to 1300.
    Additional Material: 5 Ill.
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    Vibrational spectra of thiuram sulfides: Normal coordinate analysis of tetramethylthiuram mono-, di-, and tetrasulfides (1974)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 12 (1974), S. 1001-1013 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The normal coordinate analyses of tetramethylthiuram mono-, di-, and tetrasulfides have been carried out by utilizing vibrational energies obtained from infrared and Raman spectroscopic data reported here. The C=S vibration is demonstrated to be highly coupled and to contribute to frequencies in the 850-1000 cm-1 region, but can be identified based on the strong Raman intensity. The results are useful in interpreting the spectra of these complex vulcanizing agents.
    Additional Material: 4 Ill.
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  • 54
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    Relation of elastic modulus to crosslink and entanglement concentrations in rubber networks (1974)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 12 (1974), S. 1023-1034 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The theory of rubber elasticity relates the elastic modulus of unfilled amorphous rubber to the concentration of elastically effective strands. A theoretical relation between this concentration and the concentrations of potential entanglements, random tetrafunctional crosslinks, and chain ends was proposed recently. In the present work, the new relation was combined with the theory of rubber elasticity and verified experimentally. Polydimethylsiloxane samples were cured by 60Co irradiation and were extensively extracted to determine gel fraction, which was used to calculate concentrations of crosslinking and scission due to irradiation. Equilibrium modulus values determined from creep tests were in excellent agreement with those calculated using the new relation if the average spacing between potential entanglements is 116 (CH3)2SiO units. Thus, in typical commercial silicone rubbers, the contribution to the modulus from trapped entanglements is greater than the direct contribution from crosslinks. The new relation allows the calculation of crosslink concentrations from modulus measurements on other unfilled rubbers once the potential entanglement spacing of the polymer is determined.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/pol.1974.180120601
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    Kinetics of polymer crystallization from the melt (calorimetric approach) (1974)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 12 (1974), S. 1053-1080 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Crystallization kinetics for 12 polymers including polyolefins, polyesters, polyurethanes, polysiloxanes was measured by the evolution of heat in a modified Calvet-type calorimeter over wide temperature ranges. The results are analyzed in terms of the Avrami equation and a comparison between calorimetric and dilatometric results is carried out. It is concluded that, although in the majority of cases experimental results do not obey the Avrami equation, for some polymers the agreement is rather good. The Avrami parameter obtained, however, depends on the experimental technique. Possible reasons for this disagreement are discussed. Analysis of the calorimetric crystallization rate in the vicinity of the melting point by using the kinetic theory of crystallization shows that the growth is controlled by surface (two-dimentional) nucleation. Energy parameters for the crystallites were determined and it is shown that the surface energy of the crystallites depends on the molecular structure of the polymer. Temperature dependence of the calorimetric crystallization rate of the polymers for which crystallization rates could be determined above and below the maximum rate are analyzed using a kinetic equation with common approximations for the transport term. The influence of melting conditions on the crystallization rate was studied. The results indicate heterogeneous nucleation in the polymer melt. It is concluded that this may be due both to impurities and to high regularity of macromolecules in the polymer melt.
    Additional Material: 10 Ill.
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    URL: http://dx.doi.org/10.1002/pol.1974.180120603
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    Excluded volume effect for various chain models. II. Application to optical anisotropy and end-to-end distance of branched polymers (1974)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 12 (1974), S. 1137-1143 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Monte Carlo simulation has been used to investigate the excluded volume problem for branched polymers. The mean-square optical anisotropy and mean-square end-to-end distance were examined for two models including short-range intramolecular interactions. Molecules of regular-comb and random-comb type were studied. The various effects found are discussed.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/pol.1974.180120609
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    Study of the mechanism of creep recovery by the T-jump technique (1974)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 12 (1974), S. 1255-1258 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1974.180120624
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    Correct measurement of birefringence in a nonuniform medium (1974)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 12 (1974), S. 1319-1325 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The birefringence of an object is usually obtained from its retardation. For an object of variable refractive index and optic axis orientation, a matrix procedure should be used for relating the retardation to the birefringence. There are many cases in the literature where this correct procedure has not been used. The correct procedure is illustrated for the case of a polymer spherulite.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/pol.1974.180120706
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    Relation between the critical point and the precipitation threshold (1974)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 12 (1974), S. 1865-1874 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The relationship between the critical point and the precipitation threshold is examined in the Flory - Huggins approximation with concentration-independent interaction parameter χ. Approximate explicit expressions for the difference between the critical point and the threshold can be derived by series expansion of threshold conditions. In the first-order approximation, the concentration difference depends only on the chainlength averages xw, xz, and xz+1, in the second-order approximation it depends on xw, xz, xz+1, and xz+2, etc. For polymers of low polydispersity, the second-order approximation gives a good estimate of the concentration difference; for instance, for polymers with exponential distribution and xw/xn 〈 1.25, the error is lower than ca. 1%. The approximation is not suitable for polymers with xz+1 ≫ xz (including polymers whose cloud-point curve exhibits a triple point). Irrespective of the polydispersity of the polymer, the threshold as well as the whole cloud-point curve depend only on the weight-average and higher averages, xw, xz, xz+1, …, xz+k, where k → ∞; they are, however, independent of the number average xn.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/pol.1974.180120910
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    Relaxations in the transition region of crosslinked polyesters. II. The glass transition (1974)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 12 (1974), S. 1925-1937 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The glass-transition region of crosslinked polymers prepared from poly(1,2-propylene phthalate fumarate) and styrene was studied using a torsion pendulum. The glass-transition temperature and the modulus in the rubbery region of these polymers were analyzed in terms of the crosslink density. The styrene concentration at which the maximum crosslink density occurs, as estimated from the viscoelastic data, is found to be in agreement with estimates made by other workers using chemical methods.
    Additional Material: 8 Ill.
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    URL: http://dx.doi.org/10.1002/pol.1974.180120914
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    Scattering of light from thin polymer films. I. Multiple scattering (1974)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 12 (1974), S. 1955-1968 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A general method is described to take into account the multiple scattering effect in a small-angle light scattering from thin polymer films. It is seen that multiple scattering tends to make the scattering envelope more diffuse, reducing the intensity in the high intensity regions and increasing it in the low intensity regions. The method is applied here to a spherulitic system, but it is valid for any other system where the principal scattering is in the forward direction.
    Additional Material: 8 Ill.
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    URL: http://dx.doi.org/10.1002/pol.1974.180121001
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  • 62
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    Gel permeation chromatography: Examination of column efficiencyPart V of a series on Characterization and Properties of Macromolecules. (1974)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 12 (1974), S. 1969-1977 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Gel permeation chromatographic (GPC) separations have been performed with several commercially available column packing materials. The results have been analyzed in the conventional manner to obtain the ratio of weight average to number-average molecular weight, Mw/Mn, for solutes with narrow molecular weight distribution. Various other parameters proposed to measure the efficiency of GPC columns have been evaluated and compared. It is proposed that the experimentally determined value of Mw/Mn for a series of different molecular weight samples with similar, narrow distribution for a given set of columns is a convenient parameter for comparing column efficiency in GPC. This parameter may be calculated from a single chromatogram unlike resolution, R, resolution index, RI, or specific resolution, RS, which require a pair of chromatograms. Results from the Mw/Mn method are usually in agreement with those from the R, RI, and RS calculations but one exception has been found. The number of theoretical plates calculated from the elution of a small molecule or from the polymer peak bears little relation to efficiencies predicted from the proposed Mw/Mn method or from R, RI, or RS.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/pol.1974.180121002
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    ESR study of radicals formed during tensile deformation of poly[p-(2-hydroxyethoxy) benzoic acid] fibers (1974)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 12 (1974), S. 2019-2034 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Radical formation during tensile deformation of highly oriented poly[p-(2-hydroxyethoxy)benzoic acid] fibers was investigated by electron spin resonance. Stretching of fibers in vacuo and in a stream of nitrogen gas at room temperature generated a large number of radicals which increased rapidly with macroscopic strain, while stretching in air generated only a small number of radicals. The radicals formed in vacuo or in nitrogen decayed rather rapidly after introduction of air. The observed spectrum was apparently a triplet with a line separation of about 7.5 gauss and a small asymmetry. The inspection of the hyperfine structure, line separation, and total width of the spectrum and the comparison between the observed and the calculated spectrum based on a model substance proved that the observed species is a phenoxy type radical generated by rupture of main chains. A small asymmetry of observed spectrum was explained by anisotropy of the g-tensor. The alkyl end-radical generated together with one of the phenoxy type could not be detected, perhaps owing to its high reactivity.
    Additional Material: 11 Ill.
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    URL: http://dx.doi.org/10.1002/pol.1974.180121005
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    Convergence of the distribution functions for wormlike chains (1974)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 12 (1974), S. 2075-2089 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The Daniels-type distribution functions of the end-to-end distance of three-dimensional and two-dimensional wormlike chains are obtained to terms of order t-10, by an operational method with use of a digital computer, where t is the ratio of the total chain contour length to the Kuhn segment length in three-dimensional cases and of the contour length to the persistence length in two-dimensional cases. The convergence of the ring-closure probability and the mean reciprocal distance is examined on the basis of these distribution functions. A similar study of the moment-based distribution functions is also made.
    Additional Material: 8 Ill.
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    URL: http://dx.doi.org/10.1002/pol.1974.180121009
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    Temperature dependence of viscosity-shear rate behavior in undiluted polystyrene (1974)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 12 (1974), S. 1771-1783 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The time - temperature superposition principle is well-established for linear viscoelastic properties of polymer systems. It is generally supposed that the same principle carries over into nonlinear phenomena, such as the relationship between viscosity η and shear rate \documentclass{article}\pagestyle{empty}\begin{document}$ \dot \gamma $\end{document}. Guided by this principle and the forms of various molecular theories, one would expect that η - \documentclass{article}\pagestyle{empty}\begin{document}$ \dot \gamma $\end{document} data on the same polymer at different temperatures would superimpose when plotted as η/η0 versus \documentclass{article}\pagestyle{empty}\begin{document}$ \dot \gamma $\end{document}η0/ρT, η0 being the limiting viscosity at low shear rates, ρ the polymer density, and T the absolute temperature. Data on polystyrene melts, obtained in a plate-cone viscometer, appear systematically to violate this principle in the range 140-190°. Such anomalies are absent in concentrated solutions of polystyrene. The trends are similar to those reported by Plazek in the steady-state compliance of polystyrene melts near Tg, but they appear to persist to higher temperatures than the compliance anomaly.
    Additional Material: 11 Ill.
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    URL: http://dx.doi.org/10.1002/pol.1974.180120904
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    Dilute solution behavior of polyelectrolytes. Intrinsic viscosity and light scattering studies (1974)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 12 (1974), S. 1785-1804 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The conformational character of a random copolymer of ethyl acrylate and acrylic acid (mole ratio 3:1) has been examined by intrinsic viscosity and light scattering in organic and in aqueous media. The unperturbed dimensions of this copolymer in its un-ionized state in an organic theta solvent are 1.3 to 1.4 times those obtained for the fully ionized polymer in an aqueous theta solvent. The data also suggest that a change in conformation from a swollen random coil to a compact random coil occurs in aqueous media as a function of ionic strength. These results are interpreted in terms of the hydrophobic interaction of the ester groups on the chain.An application of the wormlike chain model shows that viscosity data can be used to predict the light scattering results well with in experimental error.
    Additional Material: 8 Ill.
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    URL: http://dx.doi.org/10.1002/pol.1974.180120905
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    Optical studies of the deformation of model filled rubbers (1974)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 12 (1974), S. 1899-1924 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The strain pattern about a spherical glass bead imbedded in a stretched rubber has been calculated and used to predict the birefringence and light scattering. This is compared with experimental measurements of the retardation pattern observed using a polarization microscope and deduced from the low-angle laser Hv light scattering pattern. The agreement with theory is favorable. The light scattering is suggestive of similar origins of light scattering from crystallizing rubbers and from inhomogeneously crosslinked rubbers.
    Additional Material: 22 Ill.
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    URL: http://dx.doi.org/10.1002/pol.1974.180120913
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    Mechanism of dc electrical conductivity in poly(vinyl chloride) (1974)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 12 (1974), S. 2399-2407 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Dc conductivity measurements were performed as a function of temperature on unplasticized poly(vinyl chloride) and on PVC plasticized with various amounts of dioctylphthalate. The conductivity curves consist of two or three straight-line segments denoted I, II, and III with increasing of temperature. The intersection of segments I and II occurs at the glass-transition temperature Tg. The slope in region I is independent of the DOP concentration, while the slope in region II decreases slowly with an increase in the amount of DOP. No dependence of the conductivity on the molecular weight was found. From the conductivity curves, activation energies were evaluated below and above Tg. These satisfactorily coincide with those determined by dielectric loss or by electrical transient phenomena. A dc conduction mechanism is proposed based on electronic hopping favored by the micro-Brownian motions responsible for dielectric losses. These motions involve smaller chain lengths below than above Tg. The experimental results are discussed and interpreted in terms of the proposed mechanism.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/pol.1974.180121201
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    Pressure and temperature effects on the vibrational frequencies of crystalline polymethylenes. I. Infrared-active rocking modesThe experimental work was done in the Department of Chemistry, University of California at Berkeley, Berkeley, Ca. 94720 (1974)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 12 (1974), S. 2493-2506 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The energy level dispersion, along the chain wave vector, of infrared-active methylene rocking modes has been measured as a function of pressure to 40 kbar for a number of polymethylenes. They are crystalline polyethylene and n-paraffins C23H48, C24H50, C28H58, and C29H60. The crystalline factor-group splitting of each chain mode is observed at various pressures, for those polymethylenes which have orthorhombic or monoclinic structures. The effects of crystal structure, intermolecular force field and intramolecular force field on the observed energy levels as well as on the crystalline factor-group splittings are discussed A hydrogen-hydrogen nonbonded repulsion potential has been calculated as a function of interatomic distance rH••H for 2.3 Å 〈 rH••H 〈 3.0 Å from the observed volume dependence of the factor-group splittings of methylene rocking modes. It is shown that the dynamic potential wells along the normal coordinates of the rocking modes are harmonic up to room temperature.
    Additional Material: 10 Ill.
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    URL: http://dx.doi.org/10.1002/pol.1974.180121209
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    Change in fibrous morphology during the transformation of cellulose triacetate I to triacetate IIPart of this work was presented at the 1974 Colston Symposium on the Structure of Fibrous Biopolymers held at the University of Bristol, April 1974. (1974)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 12 (1974), S. 2583-2586 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/pol.1974.180121217
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    Thermoelasticity of weak polyelectrolyte networks (1974)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 12 (1974), S. 7-21 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The thermoelastic behavior of poly(vinyl alcohol)-poly(acrylic acid) networks was evaluated in pure water and CaCl2 solution. The ratio fe/f of the energy component of the force to the total force, evaluated without taking into account polymer-diluent specific interactions, ranged from -0.75 for networks swollen in pure water to -5.7 in 0.1M CaCl2. However, an analysis based on Flory's theory of polyelectrolyte gels yields fe/f constant at -1.32 when specific interactions are accounted for. In addition, the variation of In (r2)0 with CaCl2 concentration is 2000 times that with water. In neither pure water nor CaCl2 solution can specific interactions be neglected.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/pol.1974.180120102
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    Precipitation chromatography. III. Optimization of the experimental conditions and determination of the polydispersity of fractions (1974)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 12 (1974), S. 239-254 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The influence of the solvent-nonsolvent gradient and the temperature gradient on the efficiency of the precipitation chromatography is investigated with radically and anionically prepared polystyrene samples. Only a combination of both gradients gives optimal effectiveness of the column. The separating power of the column was determined by using mixtures of well defined samples. From the elution curves of the mixtures the nonuniformity Ufr of fractions can be estimated. For fractions of anionically prepared polystyrenes Ufr is on the average 0.001; this value is of the same order of magnitude as the statistical error. These results show that with this chromatographic method it is possible to determine the narrow molecular weight distributions of anionically prepared polystyrenes (or other polymers) with an accuracy sufficient for kinetic studies.
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    Electron spin resonance study of free radicals in the radiation grafting of butadiene to poly(vinyl chloride) (1974)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 12 (1974), S. 1189-1193 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The kinetics of the disappearance of propagating butadiene radicals produced in the grafting of butadiene to poly(vinyl chloride) was followed by electron spin resonance measurements. The radical species observed in the temperature range 213-298°K is the conjugated allylic radical: \documentclass{article}\pagestyle{empty}\begin{document}$$ \hbox{---} {\rm CH}_{2}\hbox{---}\rm{CH}\hbox{=\hskip-1pt=}{\rm CH}\hbox{---}{\rm CH}_2 \rightleftharpoons\hbox{---}{\rm CH}_2\hbox{---}{\rm CH}\hbox{---}{\rm CH}\hbox{=\hskip-1pt=}{\rm CH}_2 $$\end{document} The reaction conditions were adjusted to provide a highly viscous medium in which the propagation reaction took place. Under these conditions the radicals were stabilized and a precise ESR spectrum was obtained. Arrhenius plots of the second-order decay rate constants yield an activation energy of 5 kcal/mole. This suggests that the bimolecular termination reaction is controlled by the segmental motion of the grafted side chains.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/pol.1974.180120613
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    High-speed gel-permeation chromatography (1974)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 12 (1974), S. 1339-1345 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: To establish optimum operating conditions for high-speed gel-permeation chromatography (GPC), the effects of column packing particle size, solvent flow rate, and column length on the separation efficiency have been investigated by using monodisperse polystyrene samples and polystyrene gel columns (TSK-GEL column, Type-H). Decreasing the particle size of the column packing reduces the time required to obtain a given resolution. Monodisperse polystyrene standards were measured under the optimum operating conditions established (gel particle size 5 μ, column length 2 ft, flow rate 2.5 ml/min). The molecular weight distribution of a polymer mixture was determined in less than 10 min with the same accuracy as by the conventional GPC. Such short analysis time enables one to use GPC for in-plant quality control.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/pol.1974.180120708
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    Stress relaxation in carbon-black-filled styrene-butadiene rubber (1974)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 12 (1974), S. 1383-1394 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The tensile stress relaxation of carbon-black-filled SBR was studied in the linear viscoelasticity region as a function of temperature and volume fraction of fillers. Time - temperature superposition was valid, and master relaxation curves were obtained. Carbon black increases the modulus of the compound, especially in the rubbery region, and the time range over which the glass-rubber transition occurred. The shift factor is divided into three regions; an Arrhenius dependence in rubbery and glassy states, and Williams-Landel-Ferry (WLF) dependence in the transition region. The apparent activation energy in the rubbery state increases with the volume fraction of carbon black (or silica) and is unaffected by the structure of the filler. The increase in activation energy is caused by the attachment of rubber chains to the carbon surface. At 30% elongation, the activation energy for carbon-black-filled rubber has a value of 32 kcal/mole, independent of structure and concentration of the filler.
    Additional Material: 12 Ill.
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    URL: http://dx.doi.org/10.1002/pol.1974.180120712
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    Edge yielding in poly(vinyl chloride) films (1974)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 12 (1974), S. 579-586 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Samples of thin, unplasticized PVC films were fatigued to rupture in nitrogen and ethanol vapor. Examination of the fracture surface edges showed unusual yielding due to the proximity of an unconstrained surface. The scanning electron microscope (SEM) photomicrographs show several indications of supermolecular order in these highly oriented edges and possibly in the relatively unoriented bulk material.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/pol.1974.180120311
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    Effect of morphology on the dynamic mechanical properties of a semicrystalline polysiloxaneThis paper is part of a dissertation submitted by A. D. Murray to the Department of Metallurgy and Materials Science, Carnegie-Mellon University, in partial fulfillment of the requirements for the Ph.D. degree. (1974)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 12 (1974), S. 587-616 
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    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The dynamic mechanical properties of semicrystalline poly(tetramethyl-p-silphenylene siloxane) in three morphological preparations were measured over the wide frequency range of about 0.002 Hz to 500 Hz and the temperature range of about - 190°C to 100°C. The three samples were all isothermally crystallized at 125°C. Two samples had a spherulite size of 25 μ diameter but differed in the time allowed for secondary crystallization. The other sample had a smaller spherulite size. By assuming compliance additivity, the viscoelastic behavior could be separated into five relaxation processes with an indication that a sixth existed at low temperature. Two processes called γ1 and γ2 could be resolved at low temperatures. The γ1 process was associated with the amorphous region since the peak strength was affected by the rate of cooling through the glass transition region; the γ2 peak, unaffected by cooling rate, is attributed to the crystalline part. In the high-temperature region, the β peak is associated with the glass transition and has a shape and location that is essentially independent of the morphology. The highest temperature α2 process, whose maximum was not observed in the experimental range covered, is attributed to the crystalline region and is sensitive to changes in crystallization history. The strength of the α1 process unlike that of the other processes was found to be a function of temperature; it was associated with the noncrystalline region.
    Additional Material: 26 Ill.
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    Studies on amylose and its derivatives. X. Dilute solution conformation of amylose tripropionate (1974)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 12 (1974), S. 407-416 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Some dilute solution parameters have been measured for linear amylose tripropionate samples in ethyl acetate and tetrahydrofuran. Mark-Houwink relations for the molecular weight range 104 to 1.5 × 105 have been established, and the exponents are 0.58 and 0.61 in ethyl acetate and tetrahydrofuran, respectively. This indicates that the coil is only slightly expanded in these solvents. A value of 6.21 was calculated for the characteristic ratio C∞ leading to a steric parameter of σ = 2.32. The temperature dependence of the unperturbed dimensions (d In C∞/dT) was found to negative and of the order -4.05 × 10-3°K-1.
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    URL: http://dx.doi.org/10.1002/pol.1974.180120213
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  • 79
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    Effect of temperature and molecular weight on the rate of spreading of polystyrene melts on plane soda lime glass surfaces (1974)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 12 (1974), S. 431-439 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The effect of temperature T and weight-average molecular weight M̄w on the rate of spreading of polystyrene melts on plane solid surfaces has been examined. The activation energy E of spreading was estimated to be 25.2 ± 3 kcal/mole, which is of the same magnitude as the activation energy for flow of polystyrene melts. The rate of spreading was found to be inversely proportional to M̄w raised to the 1.5 power. This rate of spreading, measured as the time rate of increase in the liquid-solid contact area, dA/dt, could be expressed as \documentclass{article}\pagestyle{empty}\begin{document}$ dA/dt = Ke^{-E/RT} \bar M_w {}^{-1.5}\gamma _{1{\rm v}} (\cos \theta _{\rm s} - \cos \theta _{\rm d}) $\end{document} where γ1v is the melt surface tension and θd and θs are the dynamic and static contact angles, respectively. The numerical value of K has been calculated to be (6.025 ± 3.693) × 10-14 in the temperature range of 110-260°C and for the values of M̄w from 2000 to 37000.
    Additional Material: 3 Ill.
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  • 80
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    Synthesis and dynamic mechanical properties of heterogeneous network polymers from poly(L-glutamic acid) and poly(oxyethylene glycol) (1974)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 12 (1974), S. 501-513 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Heterogeneous network polymers composed of rigid polypeptide chains and flexible polyether chains were synthesized. That is, poly(L-glutamic acid) (PLGA) was crosslinked with poly(oxyethylene glycol) (PEG) at various carboxy/hydroxyl mole ratios K. The solubility tests and hydrolysis of heterogeneous network polymers suggest that the crosslinking reaction proceeds by esterification. The dynamic mechanical properties of these polymers(100 Hz, -100-200°C) are greatly influenced by the presence of a trace of water and the weight per cent of PLGA. In addition, some of these polymers show only one maximum in the temperature dispersion of dynamic loss modulus E″ and tan δ, although their shape is rather broad. The x-ray photographs of these polymers show an amorphous halo or weak Debye-Sherrer rings. These findings suggest that these polymers are not simple adducts; neverthless PLGA and/or PEG domains exist.
    Additional Material: 13 Ill.
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    URL: http://dx.doi.org/10.1002/pol.1974.180120305
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  • 81
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    On critical concentration determination (1974)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 12 (1974), S. 555-562 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The rules formulated by Koningsveld for the determination of the critical concentration are shown to be in accord with the Flory-Huggins theory. Sometimes, however, they may not refer to stable conditions, and their application in such cases will result in misleading conclusions.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/pol.1974.180120309
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  • 82
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    Rheology of poly(vinyl chloride) melts. II. Shear rate-dependent properties (1974)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 12 (1974), S. 563-578 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Four samples containing 40, 60, 80, and 97 wt-% of poly(vinyl chloride), the rest being plasticizer and stabilizer, were tested by using the Weissenberg Rheogoniometer in the steady-shearing mode at temperatures between 155 and 235°C and rates of shear \documentclass{article}\pagestyle{empty}\begin{document}$ \dot \gamma = 0.01 - 400 $\end{document} sec-1. The viscosity η versus \documentclass{article}\pagestyle{empty}\begin{document}$ \dot \gamma $\end{document} follows Graessley's theoretical dependence for infinitely entangled system. The primary normal-stress difference coefficient ψ versus \documentclass{article}\pagestyle{empty}\begin{document}$ \dot \gamma $\end{document} is well described by the same theoretical function, used with the square of its argument. The temperature dependence of η0 and ψ0 shows discontinuities at T = Tb. The numerical values of Tb can be calculated from the theory of the melting point depression due to diluent. The activation energy of viscous flow Eη below Tb is 5-9 times as large as above this temperature. The activation energy of normal stress is found to be Eψ ≈ 5Eη. The characteristic relaxation times τo, ψp, calculated from superposition of η versus \documentclass{article}\pagestyle{empty}\begin{document}$ \dot \gamma $\end{document} and ψ versus \documentclass{article}\pagestyle{empty}\begin{document}$ \dot \gamma $\end{document} data, respectively, onto Graessley's master curves, and τN, computed from zero shear parameters η0 and ψ0, differ in their sensitivity to the melting of microcrystalline regions. It is postulated that in the systems investigated, aggregates with long lifetimes are being formed, increasing the effective molecular weight and introducing changes in the effective polydispersity.
    Additional Material: 10 Ill.
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  • 83
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    Infrared spectroscopic studies of polymer transitions. III. Effects of sodium ion of glass transitions in styrene-based ionomers (1974)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 12 (1974), S. 633-633 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1974.180120315
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  • 84
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    Mechanical properties of ultra-oriented polyethylene (1974)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 12 (1974), S. 635-643 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Semicrystalline polymers generally exhibit moduli well below their theoretical limit due to chain folding and to lack of crystal alignment. Modulus increases attainable through standard drawing procedures are limited by sample fracture before large draw ratios are reached. Using an Instron capillary rheometer which allowed a draw ratio of 〉 300, transparent polyethylene strands of unusually high c-axis orientation have been produced by a combination of pressure and shear. The virtually perfect crystalline orientation and evidence for extended chains confirm that a significant improvement in modulus can be realized by this technique. The dynamic tensile storage modulus was measured by Vibron over the temperature range -160°C to +120°C. Room-temperature moduli were 7 × 1011 dyne/cm2, higher than any reported values for drawn polyethylene. Values also remained above 1011 dyne/cm2 even at 120°C. The moduli and morphological data have been related by a model consisting of an extended-chain component in paralled with a conventional drawn morphology. Experimental and calculated moduli are compared and related to available theory.
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    URL: http://dx.doi.org/10.1002/pol.1974.180120401
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  • 85
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    Effects of peroxide bonds and their degradation products on the dielectric relaxations of polystyrene (1974)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 12 (1974), S. 665-683 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Polystyrene radically polymerized in atmosphere of air is composed of bisegment (C-A) or trisegment (C-A-C) block copolymers consisting of styrene segment (A) and styrene peroxide segment (C). Dielectric measurements of a system of copolymers of styrene and oxygen were obtained above the glass temperature. Three primary relaxations, a, b, and c, in order of descending temperature, were found corresponding to three microphases: styrene phase (phase a), styrene peroxide phase (phase c), and an intermediate phase (phase b) which contains a low concentration of peroxide bonds. An alternating copolymer of styrene and oxygen exhibits the relaxation c alone. With heat treatment above the glass temperature, relaxation c and subsequently relaxation b vanish with thermal degradation of peroxide bonds. The sum of relaxation strengths is linearly related to the content of peroxide bonds which was evaluated by the elementary analysis and DTA. Below the glass temperature, the temperature dependence of dielectric loss of carefully purified polystyrene without peroxide bonds shows very weak peaks which correspond to γ (200°K at 10 kHz) and δ (50°K at 10 kHz) peaks, respectively, in the activation plot. When low molecular degradation products of peroxide bonds are occluded or impurities such as benzaldehyde are added into the specimen, the height of the γ peak is appreciably enhanced, indicating that the reorientation of small polar molecules in polystyrene accompanies the vibration of the phenyl group about the C—C6H5 bond which gives rise to the γ relaxation.
    Additional Material: 14 Ill.
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  • 86
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    New apparatus for the immersion of test sample in a liquid medium on rheovibron viscoelastometer (1974)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 12 (1974), S. 1211-1213 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/pol.1974.180120616
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  • 87
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    Further comments on the relation between hydraulic permeation and diffusion (1974)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 12 (1974), S. 1221-1230 
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    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: We feel that the lengthy comments given here come down to a few simple points. For uniform, homogeneous swollen membranes the internal driving force for transport in hydraulic permeation experiments is a concentration gradient not a pressure gradient. Equation (1) is in error because it neglects the frame of reference term 1/(1 - ν1). Equation (19) shows properly the connection between K0 and the various diffusion coefficients. In the particular case discussed here and previously we see no evidence to say that a viscous flow mechanism is operative since we can explain all of the K0 data in terms of reasonable diffusion coefficients if proper consideration is given to the frame of reference correction. This is not to say that in many other cases a viscous flow mechanism will not be present or even predominate.
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  • 88
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    Crystallization behavior of low-density polyethylene: Effects of molecular weight and branch concentration (1974)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 12 (1974), S. 1245-1249 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/pol.1974.180120622
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  • 89
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    Radiothermoluminescence. I. Radiothermoluminescence for investigation of thermal and radiation-induced crosslinking of rubber mixtures (1974)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 12 (1974), S. 1259-1265 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Phase heterogeneity of vulcanizates based on cis-polybutadiene (cis-Europrene) and SBR (Europrene 1500) blends obtained by radiation, thermal, two-stage radiation-thermal, and two-stage thermal-radiation processes was investigated by the radiothermoluminescence method. Unvulcanized blends of these polymers are found to be heterogeneous, exhibiting two glass transition temperatures Tg, which coincide with the values for the initial components. Following vulcanization, the difference between the two Tg values for a polyblend decreases. The decrease is more distinct for polyblends crosslinked at high temperatures. When the vulcanization temperature exceeds 140°C and the crosslink density (or 1/Mc) exceeds 5 × 10-5-1 × 10-4 mole/cm3, the glass temperature ranges of the crosslinked blend are practically superimposed. Such crosslinked mixtures should be considered pseudohomogeneous in phase.
    Additional Material: 3 Ill.
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  • 90
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    Statistical mechanics of two-dimensional wormlike chains (1974)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 12 (1974), S. 1327-1338 
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    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The bivariate distribution function and the ring closure probability for a continuous wormlike chain derived by Gobush et al. and by Yamakawa and Stockmayer are translated into the two-dimensional case. The results may be written in terms of Fourier series instead of spherical harmonics. Evaluation is carried out to terms of order t-3, where t is the ratio of the total contour length to the persistence length.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/pol.1974.180120707
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  • 91
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    Gel-permeation chromatographic studies of cellulose degradation. III. Methanolysis of cellulose (1974)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 12 (1974), S. 1347-1354 
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    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The molecular weight distribution in various celluloses degraded by methanolysis has been studied by gel-permeation chromatography. It is shown that the accessible portion of the sample apparently degrades preferentially into molecular fragments with a size distribution centered on species with a degree of approximately 8. This result is interpreted as indicating the presence of weak links in the cellulose chains.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/pol.1974.180120709
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  • 92
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    Unperturbed dimensions of isotactic poly(tert-butylethylene oxide) (1974)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 12 (1974), S. 1395-1406 
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    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The root-mean-square end-to-end distances of isotactic poly(tert-butylethylene oxide) fractions were determined in xylene at 80°C from intrinsic viscosity measurements and in o-dichlorobenzene at 80 and 100°C by light scattering. The characteristic dimension (〈L2〉0/M)1/2 was 1.04 × 10-8 cm in xylene and 0.9 and 0.7 × 10-8 cm in o-dichlorobenzene at 80 and 100°C, respectively. The value in xylene corresponds to a C∞ of 15.9. This observation and the large negative temperature coefficient of (〈L2〉0/M)1/2 suggest that poly(tert-butylethylene oxide) exists in a helical block conformation under these experimental conditions. This conclusion is in agreement with earlier reported NMR measurements.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/pol.1974.180120713
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  • 93
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    Small-angle light scattering and crystallization processes in solid polymer films (1974)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 12 (1974), S. 1417-1439 
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    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Information, not previously measurable, about the internal crystallization processes occurring within spherulitic films can now be obtained by combining refractive index, birefringence, and small-angle light-scattering measurements. The surroundings of a spherulite in a solid film are composed of both the adjacent spherulites and their interstices (boundaries), and it is shown that different crystallization processes can occur in each of these regions. Upon annealing a quenched isotactic polypropylene film, the rate of crystallization within the interstices of the space-filling spherulites is observed to be greater than the rate of crystallization within the spherulites themselves.
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  • 94
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    Elastic modulus of poly(isobutylene oxide) crystals parallel to the chain axis (1974)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 12 (1974), S. 1457-1463 
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    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The elastic tensile modulus of the crystalline regions parallel to the chain axis E1 for poly(isobutylene oxide) (PIBO) was determined by an x-ray diffraction method. The stress-strain (σ - ε) curve calculated from the meridional reflection of (002) shows an inflection point at about 75 MN/m2 or an extension of 0.25%. The observed moduli below and above this point are 29 and 47 GN/m2, respectively, at room temperature. The initial lower modulus agrees well with the value, 29.7 GN/m2, calculated on the basis of the double zigzag structure of PIBO chain determined by Kaji and Sakurada. The higher modulus may be due to an intrachain steric hindrance between the hydrogen atoms of the methylenic group in the main chain and those of the two side methyl groups.
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  • 95
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    Dilute solution properties and phase separation of branched low-density polyethylene (1974)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 12 (1974), S. 1499-1508 
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    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Viscosity, light scattering, and precipitation temperature measurements on dilute solutions of high-density and low-density polyethylene fractions have been carried out and a theory by Flory for phase equilibrium of linear polymers has been extended to branched polymer. From the results, it is shown that the entropy parameter ψ, depends on branching; a method for the determination of long-chain branching in polymer fractions is proposed combining precipitation temperature and molecular weight measurements. The method has been applied to the evaluation of long-chain branching in low-density polyethylene.
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    URL: http://dx.doi.org/10.1002/pol.1974.180120722
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  • 96
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    Crystallite size determination of nylon 6 by wallner's methodA part of this paper was presented at the 20th Polymer Symposium of the Society of Polymer Science, Japan, Tokyo, 1971; Proceedings, p. 675. (1974)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 12 (1974), S. 1491-1497 
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    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The crystallite sizes of α and β forms of nylon 6 along the chain axis were determined by Wallner's method. First the shifts of the maximum positions of meridional reflections from their ideal reciprocal-lattice positions were calculated for the various crystallite sizes. Second, using these relationships, crystallite sizes were estimated from the observed maximum positions of reflections. The estimated values agree well with those from the integral widths of reflections by the method of Hosemann and Wilke.
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    URL: http://dx.doi.org/10.1002/pol.1974.180120721
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  • 97
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    Dielectric properties of some semiconducting polyazophenylenes (1974)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 12 (1974), S. 1547-1553 
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    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The dielectric properties of a series of semiconducting polyazophenylenes were studied as a function of temperature and molecular weight in the temperature range 293-600°K and for molecular weights between 5,100 and 62,800 at a constant frequency of 1 kHz. The compounds studied included poly-2,4-diaminotoluene, poly-2,4-diaminoanisole, and poly-2,5-diaminotoluene. The dielectric properties are presented in the usual way in terms of a complex dielectric constant ε* = ε′ - jε″. Activation energies of relaxation processes were evaluated from the areas and widths of the dielectric loss factor, ε″, against reciprocal temperature at constant frequency. The dielectric activation energies were found to be roughly equal to the activation energies from the DC conductivity. This indicates that the conduction mechanism is based on rotational movements of molecules or parts of molecules.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/pol.1974.180120803
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  • 98
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    Low-frequency dielectric behavior of poly(vinylidene fluoride) (1974)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 12 (1974), S. 1177-1188 
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    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: An explicit mechanism is described for the anomalous increase in dielectric constant and dielectric loss at low frequencies and high temperatures for poly(vinylidene fluoride) containing ionic impurities. Relations are proposed for the ionic contributions, εi″ and εi″, to the dielectric constant and dielectric loss: \documentclass{article}\pagestyle{empty}\begin{document}$$ \begin{array}{*{20}c} {\varepsilon _i ^\prime = (2v_0 q^2 /\pi ^{1/2} lkT){\rm }(D_0 /f)^{3/2} e^{ - (3Ed/2 + W/2\varepsilon 0)/kT} } \\ \\ {\varepsilon _i ^\prime = (2v_0 q^2 /kT){\rm }(D_0 f){\rm }e^{ - (Ed + W/2\varepsilon 0)/kT} } \\ \end{array} $$\end{document} where v0 and D0 are the concentration and the diffusion coefficient of the mobile ions at infinite temperature, q is the charge of an ion (in cgs electrostatic units), l is the distance between electrodes, k is the Boltzmann constant, T is the absolute temperature, Ed is the apparent activation energy for diffusion of the ions, and W is the dissociation energy of the ionic impurities. From the slopes of curves of log εT′ versus 1/T and log ε″T versus 1/T for poly(vinylidene fluoride), energies Ed = 34 kcal/mole and W = 342 kcal/mole were obtained.
    Additional Material: 11 Ill.
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    URL: http://dx.doi.org/10.1002/pol.1974.180120612
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  • 99
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    Surface tension of polymer mixtures and copolymers (1974)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 12 (1974), S. 1195-1205 
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    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Contact angles θ of liquids of different polarity were measured on a series of mixtures of solid high polymers and a series of copolymers. The mixtures were composed of an alternating poly(ethylene-co-maleic anhydride) (EMA), and its addition product with n-octadecylamine, poly(ethylene-co-N-n-octadecylmaleamic acid) (EOM). The co-polymers were composed of the same monomeric units as the mixtures. The surface tension γs of EOM, calculated from θ by the Good-Fowkes-Owens-Wendt treatment, decreased slightly with increasing molecular weights and then reached a limiting value. Plots of γs against EOM concentration indicated large negative excess surface tension of the units with lower surface tension, EOM, in both series studied. For the mixture series, γa first sharply decreased with the EOM concentration; then it reached a limiting value, the γs of pure EOM, at a very low EOM concentration. This indicates phase separation of the two polymers, and the thickness of a monomolecular surface layer was calculated from these data. For the copolymers, γs varied logarithmically with the EOM concentration. Throughout the whole concentration range, the data fitted the equation developed by Belton and Evans for ideal mixtures.
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    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1974.180120614
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    Electronic Resource
    Electronic Resource
    Dielectric properties of polystyrene formed in a glow discharge (1974)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 12 (1974), S. 1231-1234 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1974.180120619
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