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  • Digitale Medien  (1.058)
  • 2020-2023
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  • Digitale Medien  (1.058)
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  • 2020-2023
  • 1995-1999
  • 1980-1984  (490)
  • 1965-1969  (568)
  • 1860-1869
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  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Experimental brain research 43 (1981), S. 451-454 
    ISSN: 1432-1106
    Schlagwort(e): Monocular deprivation ; Cortico-geniculate projections ; Visual cortex ; Cat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary In 16 cats monocularly deprived from 2 to 3 weeks of age, we studied 53 striate cortical cells which were identified as projecting to the dorsal lateral geniculate nucleus (LGN) on the basis of antidromic activation from LGN and of histological localization within cortical layer VI. As in the normal cat, these cortico-geniculate cells could be classified as slow, intermediate or fast, according to their axonal conduction velocities. The sampling ratio of the slow cells (mostly unresponsive to visual stimuli) was much higher than normal. On the other hand, the ratio of the intermediate (one half were simple cells) and fast cells (all except one were complex cells) was significantly lower than the norm. Also, the average axonal conduction velocities of the complex and simple cells were significantly slower than normal. These results suggest that normal maturation of cortico-geniculate cells, particularly fast and intermediate ones, is retarded or arrested by monocular visual deprivation.
    Materialart: Digitale Medien
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Experimental brain research 44 (1981), S. 41-56 
    ISSN: 1432-1106
    Schlagwort(e): Eye movements ; Dark-rearing ; Cat ; Vestibulo-ocular reflex ; Optokinetic nystagmus
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Cats reared in total darkness to adulthood have abnormal eye movements. A spontaneous nystagmus is found in the dark before any visual experience. The eye movements evoked by vestibular or optokinetic stimulation are less effective at compensation than for a normal cat. The vestibuloocular reflex (VOR) has a low gain (around 0.3) and a frequency dependent phase relation. The efficiency of optokinetic nystagmus (OKN) is poorer than for a normal cat, except for downwards stimulus movement which is followed better than normal. OKN is poorest in response to a stimulus viewed monocularly moving in the nasal to temporal direction. Neither VOR nor OKN of a dark-reared cat recover in efficiency within 5 months of the animal being brought into the light. A normal cat put into the dark for 135 days shows none of these abnormalities except an occasional spontaneous nystagmus.
    Materialart: Digitale Medien
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    Experimental brain research 42 (1981), S. 73-80 
    ISSN: 1432-1106
    Schlagwort(e): Superior colliculus ; Vestibulo-ocular responses ; Cat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary 1. Unilateral lesions of the superior colliculus were made in normal cats. Following the operation, animals exhibited a typical neglect for contralateral visual space and forced circling toward the ipsilateral side. Optokinetic nystagmus was decreased for a stimulus moving toward the ipsilateral side, particularly in the temporal-to-nasal direction when the eye contralateral to the lesion was stimulated alone. — 2. When tested in the dark, animals exhibited a strong imbalance of their vestibulo-ocular responses (VOR) to velocity steps or to sinusoidal oscillations. Rotation of the animal toward the ipsilateral side produced a VOR with a higher gain, and a shorter phase-lead than in pre-operative controls. VOR was decreased in the opposite direction to a smaller extent, however. The overall asymmetry between the two sides at the post-operative stage was about 40%. — 3. In two animals, spontaneous nystagmus was present in the dark with the fast phase toward the ipsilateral side. — 4. Visual suppression of VOR was abolished during ipsiversive rotation and was still present during contraversive rotation. — 5. The effects of unilateral colliculectomy on VOR were transient. Spontaneous nystagmus disappeared in 3 days. VOR asymmetry in the dark was no longer present after 2–3 weeks. Loss of visual VOR suppression persisted for a few more days. — 6. Superior colliculus exerts a tonic control on static and dynamic components of VOR. This control may mediate part of VOR visual modulation and provide a substitutive input for compensation of pathological VOR asymmetry.
    Materialart: Digitale Medien
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  • 4
    Digitale Medien
    Digitale Medien
    Springer
    Anatomy and embryology 162 (1981), S. 363-378 
    ISSN: 1432-0568
    Schlagwort(e): Thalamus ; Ultrastructure ; Cat ; Quantitative analysis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The ultrastructure of the ventrobasal complex (VB) of the cat thalamus was investigated in order to compare the data with those obtained in other thalamic nuclei. New data are described regarding the identification of Golgi II type neurons and several forms of axo-somatic synapses. By means of a quantitative analysis the number of different profiles, distribution of interprofile contacts, synaptic densities and degree of synaptic input of the two main cell-types were defined. The quantitative data obtained in the VB complex were compared with values for the lateral geniculate body (CGL), nucleus anterior ventralis (AV-non-sensory relay thalamic nucleus) and nucleus lateralis posterior-pulvinar complex (LP-PU-associative thalamic nucleus). The quantitative data reveal that: 1. The occurrence of RL terminals is equal in the two relay nuclei (VB and AV) and three-fold higher than in the LP-PU. 2. The percentage ratio of specific terminals (RL) in the total surface area in the relay nuclei is three-fold higher than in the LP-PU. 3. The RL→D synapses are twice as numerous in the relay nuclei as in the associative nucleus. 4. The density of synaptic RS profiles in VB is half of that found in LP-Pu. 5. In the thalamic relay nuclei the number of synaptic contacts on Golgi II type neurons is one-third of the synaptic supply of relay neurons; in the LP-Pu the amount of synaptic contacts on Golgi II type neuron approaches the synaptic supply of projective neurons.
    Materialart: Digitale Medien
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  • 5
    Digitale Medien
    Digitale Medien
    Springer
    Experimental brain research 41 (1981), S. 233-246 
    ISSN: 1432-1106
    Schlagwort(e): Cat ; Ventral tegmental area ; Locus ceruleus ; Parabrachial nuclei ; Horseradish peroxidase
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Thirty-three cat brains with injections of horseradish peroxidase in various regions of the cerebral cortex were screened for afferent projections from the ventral tegmental area, the locus ceruleus, and the parabrachial nuclei. All three structures were found to project to rather divergent parts of the cortex, including regions in the posterior half of the hemisphere. These results, especially for the ventral tegmental area and, to a lesser degree, for the parabrachial neurons, disagree with most of the target loci of established cortical afferents in the rat. Though our results might be attributed to species differences in the cortical innervation of brain stem structures, we prefer explanations which emphasize different densities in the distribution of brain stem afferents to the cortex, and/or which suggest different cortical targets of catecholaminergic and noncatecholaminergic neurons.
    Materialart: Digitale Medien
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  • 6
    ISSN: 1432-1106
    Schlagwort(e): Vestibulo-ocular reflex ; Optokinetic nystagmus ; Vestibular habituation ; Cat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary 1.Unilateral habituation of the vestibuloocular reflex was produced in adult cats stimulated by repeated unidirectional velocity steps (vestibular training) or by a continuously moving visual surround (optokinetic training). — 2. Unidirectional vestibular training produced a strong asymmetry of vestibuloocular responses (VOR). Responses to velocity steps applied to the “trained” labyrinth were decreased both in gain and in time-constant. This effect generalized to responses to sinusoidal oscillations (0.03 Hz to 0.1 Hz), i.e. to a stimulus not used during training. — No spontaneous nystagmus was ever observed in spite of the dynamic VOR asymmetry. — 3. Unilateral vestibular habituation produced by vestibular training appeared to be a long-lasting phenomenon. It was still present 10 days after the end of training. — 4. Optokinetic responses were not affected by vestibular training. — 5. Unidirectional optokinetic training produced an increase in the slow phase velocity of optokinetic nystagmus (OKN) by about 25% in both directions. This effect did not persist for more than a few minutes. A marked spontaneous nystagmus was recorded in the dark after each session of optokinetic training, with a slow phase in the direction opposite to the previous OKN. — 6. VOR in response to velocity steps and to sinusoidal oscillations were decreased unilaterally after optokinetic training. This effect was of short duration, however, and disappeared within the interval between training sessions. This lack of retention contrasted with the prolonged effect of vestibular training.
    Materialart: Digitale Medien
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  • 7
    Digitale Medien
    Digitale Medien
    Springer
    Experimental brain research 42 (1981), S. 442-452 
    ISSN: 1432-1106
    Schlagwort(e): Chemoreceptors ; C Fibers ; Vagal nerves ; Gastro-duodenal Region ; Microelectrode technique ; Cat ; Chémorécepteurs ; Fibres C ; Nerfs vagues ; Région Gastro-duodénale ; Technique des ; Microélectrodes ; Chat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Résumé La sensibilité vagale aux hydrates de carbone (glucose en particulier) et aux acides (acide chlorhydrique et acide acétique) a été étudiée dans la région gastro-duodénale chez des chats anesthésiés. Les potentiels d'action ont été enregistrés dans le ganglion plexiforme droit au moyen de microélectrodes extracellulaires. Des récepteurs, sélectivement sensibles soit aux hydrates de carbone, soit aux acides, ont été ainsi mis en évidence. Ces récepteurs doivent donc être considérés comme de véritables glucorécepteurs et acidorécepteurs. Les deux types de chémorécepteurs, silencieux au départ, présentent une fréquence de décharge basse qui varie entre 2 et 14 imp/s pour les acido-récepteurs et entre 2 et 30 imp/s pour les glucorécepteurs. Les réponses peuvent être irrégulières ou régulières et durer plusieurs minutes; leur latence est faible (entre 1 et 20 s) pour les deux types de chémorécepteurs, ce qui suggère une localisation dans la muqueuse ou au voisinage de celleci. Les fibres connectées aux glucorécepteurs et aux acido-récepteurs ont une vitesse de conduction qui varie entre 0,8 et 1,2 m/s: elles sont donc amyéliniques. L'enregistrement de l'activité électromyographique de la région gastro-duodénale a permis de montrer que les acido-récepteurs et les glucorécepteurs interviennent dans la régulation de la motilité gastrique et duodénale, l'effet le plus marqué étant une diminution du rythme électrique de base de l'estomac.
    Notizen: Summary Vagal sensitivity to carbohydrates (mainly glucose) and to acids (hydrochloric and acetic acids) was studied in the gastro-duodenal region of anesthetized cats. Action potentials were recorded extracellularly from the nodose ganglion by means of glass microelectrodes. Receptors responding to glucose perfusion were found at this level as well as receptors stimulated by acid perfusion. It is shown that each type of receptor was activated by only one kind of stimulus (carbohydrates and acids, respectively). These receptors must thus be considered as true glucoreceptors or acido-receptors. Being silent before activation, these two types of chemoreceptors discharged at a frequency that varied from 2 to 14 imp/s for the acido-receptors, and from 2 to 30 imp/s for the glucoreceptors. The response could be irregular or regular and might last several minutes. Its latency was short (between 1 and 20 s for both types of chemoreceptors. It was therefore supposed that they were located in the mucosa or neighboring structures. From the conduction velocities (0.8–1.2 m/s), it was concluded that fibers originating from the acidoand glucoreceptors belonged to the C type. Recording of the electromyographic activity from the gastro-duodenal region demonstrated that the gluco- and acido-receptors are involved in the regulation of motility of the gastric and duodenal regions.
    Materialart: Digitale Medien
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  • 8
    Digitale Medien
    Digitale Medien
    Springer
    Experimental brain research 43 (1981), S. 25-33 
    ISSN: 1432-1106
    Schlagwort(e): Cat ; LP-pulvinar complex ; MIN ; Visual texture ; Receptive field properties
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Multiple visual field representations are contained within the feline LP-pulvinar complex; regions differentiated by their afferent and efferent connectivity patterns as the striate-, tecto- and retino-recipient zones. Cell responses from these visuotopic zones were investigated in immobilized cats under N2O/O2 supplemented with pentobarbitone or Althesin, using spot, bar and textured stimuli. Response fields recorded within the LP-pulvinar complex were classified as diffuse, concentric, movement-, direction- or orientation-sensitive. Concentric receptive fields were further classified as sustained (X), transient (Y) or tonic/phasic W-cells. Direction-and movement-sensitive cells predominated in the striate- and tecto-recipient zones, respectively. Motion of noise fields, or noise bars against an identical stationary noise background elicited vigorous responses from cells in the striate zone, many showing a preference for noise stimuli. In contrast, cells from the tectal zone and other divisions of the LP-pulvinar complex were insensitive to noise. The retino-recipient zone at the lateral margin of the pulvinar nucleus was characterized by cells with concentric receptive fields, the majority exhibiting properties similar to W-cells in the LGNd. The evidence supports the notion of functional subdivision within the LP-pulvinar complex corresponding to the visuotopically organized regions defined by their connectivity patterns. Consideration of the retino-recipient zone as an extension of the LGNd-MIN complex is discussed.
    Materialart: Digitale Medien
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  • 9
    Digitale Medien
    Digitale Medien
    Springer
    Experimental brain research 43 (1981), S. 101-103 
    ISSN: 1432-1106
    Schlagwort(e): Cat ; Pyramidal tract ; Corticospinal system ; Locomotion ; Stepping
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary We studied the pattern of stepping in cats, before and after the placement of lesions in the corticospinal system. We found a deficit after the lesions, which was characterized by increased extension of the involved hindlimbs during the stance (E2–E3) phase of the step cycle. This deficit lasted two weeks or less. It may reflect loss of inhibitory influences upon extensor motoneuron pools.
    Materialart: Digitale Medien
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  • 10
    Digitale Medien
    Digitale Medien
    Springer
    Experimental brain research 43 (1981), S. 413-418 
    ISSN: 1432-1106
    Schlagwort(e): Gracile nucleus ; Plasticity ; Somatotopy ; Agenetic defect ; Cat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The somatotopic representation of the hindlimb in the gracile nucleus was studied in two cats who had a congenital defect of one hindfoot. The defect comprised all of the foot downward from and including the heel, and the distal third of tibia and fibula. The part of the sciatic nerve normally supplying the lower hindlimb and the hindfoot was reduced in diameter by one third. The motoneurones corresponding to the absent muscles were lacking and replaced by glial elements. The cross-sectional area of the dorsal columns at segment S2 was reduced by more than 20%. The gracile nuclei, in contrast, were not reduced in size. Only the diameter of its neurones was significantly smaller. Electrophysiological single and multi-neurone recordings revealed an altered somatotopic representation in the gracile nucleus on the defective side. The nuclear area normally representing the missing parts of the body surface now received input from the stump. There was no nuclear area devoid of afferent input, and there was no input in the gracile from the forelimb or from the contralateral side. It is concluded that the remaining parts of the leg project onto the gracile nucleus in an ordered fashion, sharing the entire nucleus according to their present afferent fibres.
    Materialart: Digitale Medien
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  • 11
    Digitale Medien
    Digitale Medien
    Springer
    Experimental brain research 43 (1981), S. 422-428 
    ISSN: 1432-1106
    Schlagwort(e): Retinal ganglion cells ; Cat ; Rod and cone mediated receptive fields ; Receptive field size/shape
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Receptive field centres of cat retinal ganglion cells, as mediated by rod and by cone inputs, were mapped as contours of iso-sensitivity at a mid-mesopic adapting luminance using, respec-tively, 452 nm-blue and 578 nm-yellow narrow-band lights at an intensity 1 log unit above threshold for the most sensitive locus. Based on the sizes and shapes of mapped rod and cone centres for 74 ganglion cells, four receptive field centre categories were distinguished. Cone and rod centres were usually elliptical, and in almost 60% of cells the major axis through the receptive field centre was oriented within ±20 ° of horizontal. In 69%, rod and cone centres were non-concentric, 66% had larger rod than cone centres — area ratios ranging from 0.6 ∶ 1 to 2.9 ∶ 1, and in only two cases was the rod centre actually smaller than the cone centre.
    Materialart: Digitale Medien
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  • 12
    Digitale Medien
    Digitale Medien
    Springer
    Experimental brain research 41 (1981), S. 301-309 
    ISSN: 1432-1106
    Schlagwort(e): Cat ; Auditory ; Localization ; Development
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Responses of single neurones in the inferior colliculus of anaesthetized adult cats and kittens were studied using best-frequency stimuli of varying interaural intensity difference (IID). Two broad classes of neurone, distinguished by the predominant type of input from each ear, were examined. One class of cells received predominantly excitatory input from each ear (EE cells). The other class were excited by monaural stimulation of the contralateral ear and showed no response to monaural stimulation of the ipsilateral ear, but inhibition of the excitatory response by simultaneous ipsilateral stimulation (EI cells). Fourteen of the 18 adult EI cells showed marked changes in discharge rate with variation in IID. Adult EI cells showed low response variability and were insensitive to changes in average binaural intensity. In all cases of IID sensitivity, the onset component of the response was less sensitive to IID than the sustained component. Eight out of ten EE cells were insensitive to IID over the range tested. Cells of high best-frequency in kittens younger than 28 days showed irregular changes in discharge rate with variation in IID and wide response variability. Some low-frequency EI cells in young kittens showed sensitivity to IID, but it is unlikely that these could be involved in sound localization as their frequency response was inappropriate. Many cells in kittens aged 31–40 days showed monotonic, adult-like IID functions, but the response variability of these cells remained higher than that of adult cat neurones. These data provide evidence for a developmental change of binaural interaction in the cat.
    Materialart: Digitale Medien
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  • 13
    Digitale Medien
    Digitale Medien
    Springer
    Experimental brain research 41 (1981), S. 329-337 
    ISSN: 1432-1106
    Schlagwort(e): Caudate nucleus ; Golgi/EM ; Corticocaudate projection ; Cat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary A combined Golgi/electron microscopic technique was used to investigate the fine structure and synaptology of Golgi-stained spiny neurons in the caudate nucleus of the cat. In order to study the termination sites of cortical afferents on Golgistained spiny neurons, cortical fibres were caused to degenerate by making extensive cortical lesions 3 days prior to fixation of the animals. When examined in the electron microscope, perikarya of labelled spiny neurons have a round nucleus, a few mitochondria and microtubules, and a poorly developed Golgi apparatus and rough endoplasmic reticulum. Only rarely are axo-somatic contacts seen. Labelled dendrites exhibit a moderate number of microtubules and sometimes elongated mitochondria. Numerous labelled spines are seen in the vicinity of their parent dendrites. They are contacted by smaller type I and type III boutons and larger type IV boutons (Hassler et al. 1978). Large boutons filled with clear round vesicles establish symmetric contacts with labelled dendritic shafts. Degenerating boutons of cortical afferents are seen in contact with spines and, more rarely, with dendritic shafts of Golgi-stained spiny neurons. All degenerating boutons synapsing with labelled structures are found some distance from the cell body. No contacts of degenerating cortical boutons with the soma or with stem dendrites of Golgi-stained spiny neurons are found.
    Materialart: Digitale Medien
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  • 14
    Digitale Medien
    Digitale Medien
    Springer
    Experimental brain research 42 (1981), S. 196-202 
    ISSN: 1432-1106
    Schlagwort(e): Retina ; Sampling theorem ; Brisk, X and Y, ganglion cells ; Cat ; Visual acuity
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The relationship of brisk transient and brisk-sustained unit cut-off frequencies to their respective array cut-off frequencies has been calculated by means of sampling theory from the corresponding α and β-mode cell densities at various retinal eccentricities. Interpretation of the results depends on whether on and off cells of each class are functionally homogeneous or heterogeneous populations. In agreement with expectations from sampling theory for a system involved in resolution tasks, it is found that the brisk-sustained system has less potential for undersampling and spurious imagery than the brisk-transient system, which is thought to play a different role. The brisk-sustained array could avoid such aliasing altogether if it is functionally heterogeneous. The differences between the two systems are similar to those between insect eyes respectively optimised for high resolution vision or the detection of high velocity image motion.
    Materialart: Digitale Medien
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  • 15
    Digitale Medien
    Digitale Medien
    Springer
    Experimental brain research 44 (1981), S. 409-418 
    ISSN: 1432-1106
    Schlagwort(e): Oculomotricity ; Lateral rectus and retractor bulbi motoneurones ; Infraorbital nerve ; Vibrissal pad ; Cat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Responses from lateral rectus, medial rectus and retractor bulbi nerves were obtained following electrical stimulation of the vibrissal pad of the cat. Discharges in afferent fibres dissected from the infraorbital nerve were recorded during movements of the vibrissae and following electrical stimulation of the vibrissal pad. Both stimuli activated the same population of Aα fibers. Intracellular records were obtained from lateral rectus motoneurones identified antidromically in the principal abducens nucleus and from retractor bulbi motoneurones similarly identified in the accessory abducens nucleus. EPSPs (3 mV) were recorded in lateral rectus motoneurones following electrical stimulation of the ipsilateral vibrissal pad at a latency of 3.5 ms. Large-amplitude disynaptic EPSPs (15 mV) were recorded in retractor bulbi motoneurones following the same vibrissal stimulation. The synaptic excitation evoked in both lateral rectus and retractor bulbi motoneurones through stimulation of the ipsilateral vibrissal pad induced an early retraction followed by an abduction of the eye ball. The hypothesis is that the vibrissal message might complement other sensory modalities in the generation of patterned eye movements.
    Materialart: Digitale Medien
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  • 16
    Digitale Medien
    Digitale Medien
    Springer
    Experimental brain research 44 (1981), S. 431-436 
    ISSN: 1432-1106
    Schlagwort(e): Cat ; Visual cortex ; Orientation columns ; Deoxyglucose
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Three-dimensional reconstructions of the orientation column system were obtained from the visual cortex of four cats using the deoxyglucose technique. One cat had normal visual experience, one was monocularly deprived and two had selective experience with vertical and horizontal contours, respectively. In areas 17 and 18 orientation columns form a remarkably regular system of equally spaced parallel bands whose trajectory is orthogonal to the borderline between areas 17 and 18. This topographic organization is resistant to manipulations of early visual experience.
    Materialart: Digitale Medien
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  • 17
    Digitale Medien
    Digitale Medien
    Springer
    Experimental brain research 44 (1981), S. 437-440 
    ISSN: 1432-1106
    Schlagwort(e): Response variability ; Visual cortex ; Cat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The relationship between the variance and mean rate of discharges of simple cells in the cat striate cortex has been examined when mean rate was varied by changing either stimulus spatial frequency or contrast. In both cases, the variance was related to the mean discharge rate by an exponent of about 1.15; the relation was thus roughly linear. The discharge variance was on average 1.7 times the mean rate for data obtained from measurements of the neurones' spatial frequency tuning curves, and 1.48 times the mean for data from the response-contrast determination. However, this difference was not statistically significant.
    Materialart: Digitale Medien
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  • 18
    Digitale Medien
    Digitale Medien
    Springer
    Experimental brain research 41 (1981), S. 420-426 
    ISSN: 1432-1106
    Schlagwort(e): Vestibular nystagmus ; Cat ; Visual suppression ; Vertical asymmetries ; Nystagmus vestibulaire ; Chat ; Suppression visuelle ; Asymétries verticales
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Résumé Chez le chat, l'asymétrie des réponses nystagmiques verticales à une rotation autour d'un axe interaural a été caractérisée en mesurant la fréquence de battement et le gain du réflexe vestibulooculaire dans chaque sens vers le haut et vers le bas. Des variations sinusoïdales de la vitesse de la tête, ou des échelons de vitesse ont été exercés dans trois conditions visuelles: à l'obscurité (stimulation vestibulaire pure); à la lumière (stimulation mixte vestibulaire et optocinétique); et enfin, alors qu'un miroir placé devant l'animal et solidaire du mouvement de sa tête lui fournissait une référence visuelle stable (vision stabilisée). Dans les trois conditions, la fréquence de battement et le gain du nystagmus vers le bas (désigné par le sens des phases rapides) sont plus grands que ceux du nystagmus vers le haut. A l'obscurité, les caractéristiques des nystagmus postrotatoires suggèrent une constante de temps plus longue pour le réflexe vestibulo-oculaire vers le bas que vers le haut. A la lumière, les deux stimulations agissent synergiquement. En vision stabilisée, la suppression du nystagmus s'exerce préférentiellement sur le nystagmus haut, ce qui appuie l'hypothèse d'une addition algébrique des effets des deux stimulations.
    Notizen: Summary In the cat, the asymmetry of vertical nystagmus in response to a rotation around the Yaxis has been characterized by measuring the beat frequency and gain of vestibulo-ocular reflexes in each direction (upward and downward). Sinusoidal variations of head velocity or velocity steps have been applied under three visual conditions (a) in darkness (pure vestibular stimulation); (b) in the light (mixed vestibular and optokinetic stimulation); (c) with a mirror placed in front of the animal; since the mirror image moved with the head, the animal was provided with a stable visual cue (stabilized vision). In all three conditions, beat frequency and gain were greater for downward than for upward nystagmus (the direction refers to that of the quick phase). In darkness, the characteristics of postrotatory nystagmus suggested a greater time constant for downward than for upward vestibulo-ocular reflexes. In the light, both stimuli acted synergistically. In stabilized vision, upward vestibular nystagmus was preferentially suppressed, suggesting an algebraic summation of the effects arising from both kinds of stimuli.
    Materialart: Digitale Medien
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  • 19
    Digitale Medien
    Digitale Medien
    Springer
    Experimental brain research 42 (1981), S. 89-98 
    ISSN: 1432-1106
    Schlagwort(e): Receptive field ; Single unit ; Striate cortex ; Simple cell ; Cat ; Model stimulation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The receptive field organization of simple cells was studied by analyzing interaction effects between two stationary flashing light stimuli. One stimulus was positioned in the most responsive part of the receptive field to produce activity against which the effects of the other stimulus in various positions of the visual field could be determined. The receptive field was subdivided into an elongated center and elongated antagonistic flanks. The effects on the flanks were always considerably stronger on one side. Powerful flank suppression could be elicited within a region which usually was only slightly wider than the receptive field center. The suppression was just as stimulus specific as the activation of the center and occurred only by light ON or OFF. The cells were classified into ON-dominant and OFF-dominant depending on the kind of response found in the center. In ON-dominant cells the strong flank suppression occurred only by light ON, and light OFF produced enhancement. Correspondingly, the strong flank suppression occurred only by light OFF in OFF-dominant cells. This is consistent with the interpretation that simple cells have excitatory and inhibitory input from the same type of cells in the lateral geniculate nucleus (LGN), i.e., only from ON-center or OFF-center cells. The small size of the area where strong flank suppression occurred shows that inhibition comes from a few LGN cells rather than from a large pool of cells. A model for simple cell receptive fields presuming overlapping but acentric excitatory and inhibitory fields with input to both fields from either ON- or OFF-center LGN cells was tested by computer simulation and shown to fit the experimental data.
    Materialart: Digitale Medien
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  • 20
    Digitale Medien
    Digitale Medien
    Springer
    Experimental brain research 42 (1981), S. 99-107 
    ISSN: 1432-1106
    Schlagwort(e): Receptive field ; Single unit ; Striate cortex ; Complex cells ; Cat ; Model simulation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The receptive field organization of complex cells was studied by analyzing interaction effects between two stationary flashing light stimuli. One was placed in the most responsive part of the receptive field to produce activity against which effects of the other in different visual field positions could be determined. The receptive field was spatially organized into antagonistic center and flanks just like the fields of simple cells. However, both center and flanks were found within the receptive field area where a single slit evoked discharge. Center and flanks were elongated along the optimal stimulus orientation. The flanks were displaced from the center normal to optimal stimulus orientation. In the center, ON- and OFF-responses were usually about equal in strength and the maximum ON- and OFF-responses occurred in about the same position. This shows that complex cells are activated by input from both ON- and OFF-center cells in the lateral geniculate nucleus (LGN) where the receptive field centers of the LGN cells overlap closely. This explains most of the specific features of complex cells, e.g., the spatially overlapping ON- and OFF-zones, the large response field, the repetitive firing when a slit moves over the receptive field, and the marked non-linear spatial summation. Strong flank suppression occurred with both ON and OFF. The effects were usually stronger on one side of the center. Maximal suppression occurred on the same side with both ON and OFF. This is consistent with the interpretation that complex cells are inhibited by input from both LGN ON- and OFF-center cells with overlapping receptive field centers. A model presuming that complex cells have overlapping but acentric excitatory and inhibitory fields was tested by computer simulation and shown to fit the experimental data. This is the same model as presented for simple cells in the preceding paper (Heggelund 1980), except that the excitatory and inhibitory fields of simple cells have input from either ON- or OFF-center LGN cells, whereas in complex cells they have input from both types.
    Materialart: Digitale Medien
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  • 21
    Digitale Medien
    Digitale Medien
    Springer
    Experimental brain research 42 (1981), S. 146-157 
    ISSN: 1432-1106
    Schlagwort(e): Nucleus tractus opticus ; Visual response ; Direction specificity ; Optokinetic nystagmus ; Cat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary All cells in the nucleus of the optic tract (NOT) of the cat, that Bcould be activated antidromically from the inferior olive, were shown to be direction-specific, as influenced by horizontal movements of an extensive visual stimulus. Cells in the left NOT were activated by leftward and inhibited by rightward movement, while those in the right NOT were activated by rightward and inhibited by leftward movement. Vertical movements did not modulate the spontaneous activity of the cells. The mean spontaneous discharge rate in 50 NOT cells was 30 spikes/s. This direction-specific response was maintained over a broad velocity range (〈0.1 ° – 〉100 °/s). Velocities over 200 °/s could inhibit NOT cells regardless of stimulus direction. All cells in the NOT were driven by the contralateral eye, about half of them by the ipsilateral eye also. In addition, activation through the contralateral eye was stronger in most binocular units. Binocular cells preferred the same direction in the visual space through both eyes. An area approximately corresponding to the visual streak in the cat's retina projected most densely onto NOT cells. This included an extensive ipsilateral projection. No clear retinotopic order was seen. The most sensitive zone in the very large receptive fields (most diameters being 〉20 °) was along the horizontal zero meridian of the visual field. The retinal input to NOT cells was mediated by W-fibers. The striking similarities between the input characteristics of NOT-cells and optokinetic nystagmus are discussed. The direction selectivity and ocular dominance of the NOT system as a whole can provide a possible explanation for the directional asymmetry in the cat's optokinetic nystagmus when only one eye is stimulated.
    Materialart: Digitale Medien
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  • 22
    Digitale Medien
    Digitale Medien
    Springer
    Experimental brain research 44 (1981), S. 177-186 
    ISSN: 1432-1106
    Schlagwort(e): Posture ; Movement ; Motor cortex ; Cat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The influence of postural support on posturo-kinetic co-ordination has been studied with a model of movement consisting of limb flexion induced by stimulation of the motor cortex in chronically implanted cats. To more easily quantify the responses by measuring the vertical forces exerted at the level of the four limbs, only weak stimuli were used, mainly triggering isometric motor activity. The aim of the study was to analyse the influence on the motor responses of various postural supports leading to a weight distribution between the limbs which differs from the normal situation. Three kinds of initial posture were tested. The first was obtained by directing the head of the cat to the left or to the right. The second type consisted in raising one or two of the platforms supporting the limbs. The third was obtained by adding a load to one of the limbs. The main results established in these conditions were the following: The latencies of the beginning of the movement and its associated postural adjustment, as revealed by the onset of force changes, were independent of the initial postural situation. Whatever the initial weight distribution, the amplitudes of force variations induced by given intensities of cortical stimulation were generally constant, though small variations of amplitude were noted in some cases. When there were changes in the response amplitudes, all four limbs were generally affected. The effect was observed whatever the limb concerned by modification of the support. This not only means that the postural responses depend on the amplitude of the movement but also that the amplitude of the movement itself may be modified according to perturbations affecting the postural limbs. Comparison of the present data with previous results leads to the hypothesis that a postural reference is taken into account in the determination of amplitudes of responses to cortical stimulation.
    Materialart: Digitale Medien
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  • 23
    Digitale Medien
    Digitale Medien
    Springer
    Pflügers Archiv 391 (1981), S. 226-230 
    ISSN: 1432-2013
    Schlagwort(e): Central chemosensitivity ; Morphology ; HRP ; Labelling ; Mapping ; Medulla oblongata ; Cat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract A modified horseradish peroxidase labelling technique was used to study the distribution pattern of neurons in the central chemosensitive fields of the medulla oblongata of cats. In several cryosectioned medullae a mapping of superficially located HRP-labelled neurons was achieved. The distribution and configuration of the labelled neurons indicate that most of them belong to the nucleus paragigantocellularis lateralis. However, by varying the time of incubation it was possible to identify different types of neurons. On the basis of certain aspects of the HRP incorporation mode and neuronal topography a specific type of small-sized neurons has been identified. Some functional implications of these small neurons with respect to their possible chemosensitive activity are discussed.
    Materialart: Digitale Medien
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  • 24
    Digitale Medien
    Digitale Medien
    Springer
    Pflügers Archiv 389 (1981), S. 143-148 
    ISSN: 1432-2013
    Schlagwort(e): Retractor bulbi muscle ; Trigeminal afferents ; Oculomotricity ; Cat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract The effects of vestibular and trigeminal stimulation on reflex responses of each slip of the retractor bulbi muscle were tested by recording the electromyogram. 1. In “encéphale isolé” cat, phasic electrical stimulation of the horizontal canal induced no response in the RB slips. Repetitive vestibular stimulation did not produce nystagmus in the RB muscle while strong muscular discharges were observed in the nystagmus lateral rectus muscle. 2. In anaesthetized cats, three trigeminal inputs elicited strong reflex responses in each slip of the RB muscle. Electrical stimulation of the vibrissae or the infra-orbital nerve evoked a two component reflex response (latencies: 5ms±0.5 and 14ms±2). Electrical stimulation of the supraorbital nerve elicited a single component reflex response (latency: 6ms±0.5). Electrical stimulation of the long ciliary nerves evoked a complex response with four components (latencies: 7.5ms±0.5, 10ms±2,15ms±2,20ms±2) 3. Pentobarbital and morphine produced lasting depression of the reflex responses of the RB muscle. The depressive effect of morphine was reversed by naloxone.
    Materialart: Digitale Medien
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  • 25
    Digitale Medien
    Digitale Medien
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 317 (1981), S. 168-172 
    ISSN: 1432-1912
    Schlagwort(e): Paraoxon ; Blood pressure ; Vertebral artery ; Central muscarinic receptors ; Cat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Application of paraoxon into the left vertebral artery (8–80 μg) or both the left and right vertebral artery (4–8 μg) of the anaesthetized cat evoked dose-dependent depressor effects, whereas heart rate was not influenced significantly. Also after systemic administration of paraoxon (150–825 μg·kg−1), while peripheral muscarinic receptors were blocked, depressor effects were still observed. Dose-response curves for the depressor response to paraoxon were established. Infusion of low doses of dexetimide via the vertebral artery prevented the hypotensive action of paraoxon. The distribution of this antimuscarinic drug in the brain was investigated. The depressor effect of paraoxon can be attributed to both a decrease in peripheral resistance and cardiac output. Decerebration and midcollicular transection were carried out in order to elucidate the site and mechanism of action. The depressor effect of paraoxon seems to be mediated by a central mechanism of action located within the lower brain stem. It is concluded that stimulation of muscarinic receptors in the pontomedullary region gives rise to the observed changes in haemodynamic parameters. Muscarinic receptors in the hypothalamus seem to be of minor importance for the hypotensive action of paraoxon.
    Materialart: Digitale Medien
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  • 26
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 216 (1981), S. 557-568 
    ISSN: 1432-0878
    Schlagwort(e): Electron microscopy ; Neuroglia ; Silver impregnation ; Brain ; Cat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The silver-impregnation procedure of Tsujiyama is suitable for demonstration of all three classical types of neuroglial cells; in the present study it was used for electron microscopic identification of neuroglial cells in the brain of the cat. The aim of the present study was 1) to determine impregnated structural correlates of neuroglial cells at the light- and electron-microscopic levels, and 2) to determine whether the method of Tsujiyama is applicable for the electron microscopic identification of the single types of neuroglial cells. Silver deposits were observed over the cytoplasm and processes of astrocytes where numerous glial filaments were present. Oligodendrocytes and microglial cells may be precisely differentiated by use of Tsujiyama's silver impregnation method at the electron microscopic level due to the pattern of silver-deposition in these two basic types of cells. This silver-impregnation method combined with electron microscopy is thus suitable for a precise identification of neuroglial cells; the technique may prove to be very helpful in identification of such categories of neuroglial cells that encompass also the images of cells which cannot be classified by use of the standard methods.
    Materialart: Digitale Medien
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  • 27
    Digitale Medien
    Digitale Medien
    Springer
    European archives of oto-rhino-laryngology and head & neck 233 (1981), S. 1-12 
    ISSN: 1434-4726
    Schlagwort(e): CM ; SP ; Hirnstamm-Reaktion ; Katze ; Entwicklung ; CM ; SP ; Brainstem response ; Cat ; Development
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Summary The development of the surface-recorded cochlear and early neural potentials has been studied in the cat from birth to the 8th post-natal week. CM, SP, and each of the neural waves has a characteristic temporal developmental pattern and mature threshold. Wave IV is the most resistant to reduction in stimulus intensity levels, while the thresholds of both cochlear potentials are high. Animals with hereditary unilateral deafness constitute a most convenient model for the study of functional maturation in the auditory pathways, particularly with regard to precise latency estimations.
    Notizen: Zusammenfassung Die Entwicklung der an der Oberfläche registrierten cochlearen und frühen neuralen Potentiale wurde bei der Katze von der Geburt bis zur 8. Woche studiert. CM, SP und jeder der neuralen Wellen haben ein charakteristisches altersbedingtes Entwicklungsmuster und eine Responsschwelle. Welle IV wird am wenigsten von einer Reduktion in der Stimulusintensität beeinflußt. Die Schwelle der beiden cochlearen Potentiale sind dagegen erhöht. Tiere mit angeborener einseitiger Taubheit sind bestens geeignet für das Studium der funktionellen Reifung der Gehörbahnen, besonders in bezug auf die exakten Latenzzeitmessungen.
    Materialart: Digitale Medien
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  • 28
    Digitale Medien
    Digitale Medien
    Springer
    European archives of oto-rhino-laryngology and head & neck 230 (1981), S. 251-255 
    ISSN: 1434-4726
    Schlagwort(e): Ganglion Scarpae ; Katze ; Labyrinthektomie ; Scarpa's ganglion ; Cat ; Labyrinthectomy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Summary One year after membraneous labyrinthectomy in three cats a quantitative analysis of neurons in Scarpa's ganglion was performed under the light microscope. Total numbers of neurons were found 30% lower than in the respective contralateral ears. Although remaining perikarya showed signs of degeneration, such as shrinkage and vacuoles the proportions of large and small neurons remained unchanged after this procedure.
    Notizen: Zusammenfassung Ein Jahr nach Labyrinthektomie wurde eine quantitative Analyse der Neuronen im Ganglion Scarpae der Katze durchgeführt. Die Gesamtzahl der Perikarya war 30% niedriger als in den unoperiert belassenen kontralateralen Ohren. Obwohl die verbleibenden Neuronen degenerative Veränderungen wie Schrumpfung und Vakuolen aufwiesen, waren die Anteile an großen und kleinen Neuronen unverändert.
    Materialart: Digitale Medien
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  • 29
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 27 (1981), S. 13-20 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: A suboptimal control algorithm is derived for a continuous latex reactor subject to deterministic and stochastic disturbances to control the pathological behavior of the reactor. An extended Kalman filter based on an instantaneous local linearization technique is used to estimate the reactor states, and a quadratic performance index is used to derive the suboptimal feedback control law. This study successfully demonstrates the application of the multivariable control theory to the control of a simulated continuous latex reactor operating under limit-cycle conditions. The mathematical model used for the control studies was previously developed and has been shown to describe the performance of an actual reactor system extremely well over its entire range of operation.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
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  • 30
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 27 (1981), S. 33-40 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Infinite dilution activity coefficients (γ∞) in binary liquid mixtures are data of wide practical and theoretical applicability, but their extensive use has been hindered by the experimental limitations of classical vapor-liquid equilibrium techniques. Two new experimental methods for accurate γ∞ determinations are presented. These techniques, both faster and more accurate than classical methods, are complementary, and their applicability to different types of binary systems is discussed.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
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  • 31
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 27 (1981), S. 59-65 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Kerosine or propane was injected near the base of a small, air-fluidized bed of sand at 940°C. The fraction of fuel burnt within the bed was determined from a heat balance, for various particle sizes, fluidizing velocities, and bed depths.Assuming the initial formation of a train of fuel vapor bubbles, theoretical analysis indicated two stages of combustion: (1) rapid consumption of the oxygen initially between fuel vapor bubbles; (2) slow consumption of oxygen initially outside the fuel vapor region by radial diffusion of oxygen and fuel vapor, analogous to a diffusion flame.Comparison of experiment with theory gave effective radial diffusion coefficients of the same order of magnitude as the molecular diffusion coefficient. It was inferred that combustion occurs largely by a diffusion flame within the bed, with diffusion through the particulate phase being the rate-controlling step. This explains why fuel distribution is so important in attaining efficient combustion.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
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  • 32
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The gas chromatography technique was applied to measurements of diffusion of n-butane in zeolite NaY. The linear chromatography theory failed to explain these results quantitatively, and a significant system nonlinearity was demonstrated. This nonlinearity is likely associated with non-Fickian diffusion. Order of magnitude estimates of the diffusivity could still be obtained, however. Over the range of temperatures 105 to 240°C, the n-butane diffusivities were in the range 10-8 to 10-6 cm2/s. Similar results were obtained with n-hexane and calculated diffusivities were about an order of magnitude smaller than the corresponding n-butane values. In contrast, limited experiments with cyclohexane, 2, 2-dimethylbutane, and trans-decalin were entirely consistent with the linear chromatography theory. At the measurement temperatures, the intracrystalline diffusion was too rapid to be detected in any of these systems. Attempts to operate at lower temperatures where diffusion might be significant were frustrated by extensive peak broadening and concomitant loss of detector response.
    Zusätzliches Material: 13 Ill.
    Materialart: Digitale Medien
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  • 33
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 27 (1981), S. 125-131 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Alteration in concentration-independent catalyst decay rates due to the presence of finite external and internal mass transfer resistances is examined. Analytical expressions for external and overall time-dependent catalytic effectiveness are developed. Analysis of diffusion-limited catalyst deactivation in flow reactors is discussed.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
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  • 34
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 27 (1981), S. 138-148 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: A correlation is developed for the solubility of hydrogen in hydrocarbon solvents at temperatures from 310 to 700 K and pressures to 30 MPa (300 bar). The fugacity of dissolved hydrogen at zero pressure is correlated as a function of solubility parameter and temperature. The high-pressure fugacity is obtained upon applying a Poynting factor for which the required partial molal volume of hydrogen is also correlated in terms of solubility parameter and temperature. The Henry constant of hydrogen is included in the correlation. The correlated results are compared with experimental data for 22 systems of binary and ternary solutions and five narrow-boiling cuts of coal liquids. The overall average absolute deviation for all systems studied is approximately 6%.
    Zusätzliches Material: 13 Ill.
    Materialart: Digitale Medien
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  • 35
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 27 (1981), S. 120-125 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The interrelation between internal diffusion and concentration-independent deactivation is examined using a simple mathematical model. Analytical procedures are developed for evaluating the performance of single catalyst particles in the presence of diffusion and deactivation. By incorporating time-dependent effectiveness factors in design equations, reactor performance under the combined influence of diffusion and deactivation is predicted. By analogy to the effectiveness factor for non-deactivating systems, the concept of a deactivation effectiveness factor is introduced.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 36
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 27 (1981), S. 159-162 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 37
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 27 (1981), S. 163-166 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 38
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 27 (1981), S. 170-172 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 39
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 27 (1981), S. 174-174 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 40
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 27 (1981) 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 41
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 27 (1981), S. 203-207 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: A new static cell for vapor-liquid equilibria up to 100 MPa between 233 and 433 K is presented. A detachable sampling microcell and a special chromatographic injector are used in a new sampling system suitable for gas chromatographic analysis of mixtures with high boiling components. The test system is N2 - n-Heptane at 305.45 K.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
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  • 42
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 27 (1981), S. 193-202 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Dust particles originally generated by two steelmaking processes were dispersed in an air stream and passed through a pilot-scale high gradient magnetic filter. In accordance with theoretical predictions, the experimental results showed that collection was improved by increasing the depth or density of the steel wool filter, increasing the applied magnetic field, or decreasing the filtration velocity. Collection efficiency increased with particle size up to about 2 μm, above which the efficiency tapered off, apparently due to reentrainment effects. Collection efficiencies of greater than 99% were obtained, indicating that high gradient magnetic filtration may be a practical method of controlling particulate emission from processes in the iron and steel industry.
    Zusätzliches Material: 14 Ill.
    Materialart: Digitale Medien
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  • 43
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 27 (1981), S. 284-292 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The existence of multiple stable and unstable steady states in a continuous stirred tank biological reactor (CSTBR) was demonstrated experimentally for the first time. These experiments resulted in the determination of growth rate, yield and intermediate metabolite concentration data entirely from continuous culture. This information was used to qualitatively interpret the stability behavior in terms of the biochemistry and bioenergetics of substrate metabolism.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
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  • 44
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 27 (1981), S. 301-303 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 45
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Zusätzliches Material: 17 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 46
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 27 (1981), S. 316-316 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 47
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 27 (1981) 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 48
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 27 (1981), S. 372-377 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: This paper presents numerical solutions to the nonlinear, coupled boundary-layer equations governing laminar condensation heat and mass transfer in the vicinity of the forward stagnation point of a spherical cold water droplet translating in a saturated mixture of three components. The environment surrounding the droplet is composed of a condensable (steam), a noncondensable and nonabsorbable (air), and a third component which is noncondensable but absorbable (Elemental Iodine, for example). The dispersed and the continuous phases have been treated simultaneously. Results obtained here show excellent agreement with experimental results where available. An important conclusion is that for laminar condensation on a freely falling droplet, for a given thermal driving force and noncondensable gas concentration in the bulk, the dimensionless heat transfer decreases with increasing saturation temperature of the outside medium.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
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  • 49
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 27 (1981), S. 396-403 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Simultaneous biological and activated-carbon treatment of organic wastewaters appears promising. The effects of bacterial film growth on adsorbent particles is investigated by laboratory work and mathematical modelling. Regeneration of the adsorbent due to film growth does occur, but faster than predicted. The discrepancy reflects uncertainty about the structure of bacterial films.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 50
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 27 (1981), S. 429-442 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The development of processes requires the consideration of a wide variety of reactions which are required to transform raw materials into desired products, solve separation problems, and heat or cool process streams. These reactions have to be evaluated on the basis of raw material costs, kinetics, potential separation difficulties, catalyst costs, safety and reliability, as well as other factors that would arise in their industrial implementation. In this paper, the current status of research in reaction path synthesis has been reviewed. Details have been presented on the REACT program that has been developed for the synthesis of reaction paths for industrial organic chemicals.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 51
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 27 (1981), S. 277-284 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: A calculational method is proposed for the simulation of steady-state, multisolute, countercurrent extraction with axial dispersion. The method provides for complex chemical-equilibrium and phase-equilibrium relationships, and accounts for the individual resistances of the liquid phases in the calculation of mass-transfer rates. The solution procedure follows that developed by Newman (1967, 1968) for systems of simultaneous, second-order difference equations.Three example problems are solved to demonstrate the efficiency and flexibility of the method. These include (1) an example from McSwain and Durbin (1966), (2) calculation of axial-dispersion and mass-transfer parameters from experimental data for the extraction of acetic acid from water by a tertiary amine in an RDC extractor, and (3) simultaneous extraction of solutes that interact in an acid-base complexing reaction at the liquid-liquid interface. The examples all assume that extraction is governed by interphase mass-transfer rates and cell-wise backmixing; however, the method is also applicable to equilibrium-stage separators, separators described by the diffusional model of axial dispersion, and other countercurrent separation processes.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 52
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 27 (1981), S. 312-315 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 53
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 27 (1981), S. 588-592 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Quantitative measurements of the effect of a third phase of buoyant solid particles on the settling rates of suspensions of heavy particles are reported. It is found that for a wide range of concentration of both buoyant and heavy particles, the settling rates of both solid phases are greatly increased. If the phases are dilute, the settling velocities of both are retarded. The total settling time of heavy particles can be halved, but only under conditions that the light phase is unaccelerated. This suggests that small gas bubbles would form a more satisfactory buoyant phase. The high concentrations of thickened suspensions which result from the acceleration process are also reported.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 54
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 27 (1981), S. 632-636 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 55
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 27 (1981), S. 673-679 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: A procedure for inserting vapor pressure data in the equations of state is presented. It provides a straightforward scheme for the extension of direct methods to the study of phase equilibria of polar mixtures and of solutions containing nonvolatile electrolytes. Some examples of application are also given.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 56
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 27 (1981), S. 861-863 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Experimental data and theory both support the contention that there is a maximum solubility in solid-fluid equilibria. An example system, naphthalene-ethylene, at temperatures between the upper and lower critical end points and at pressures from 1 to 1000 bar is considered. There is also a solubility minimum in this system.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 57
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 27 (1981), S. 829-836 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: A general analysis of a cascade of identical recycle units is presented by means of studying the fluid history inside the system. This is an extension of Part I (Mann et al., 1979) in which a single recycle unit was analyzed. The history of a fluid element is expressed in terms of the number of cycles it completes, the time it resides in the system and the total time it resides in a specific section of the system - all are random variables. Concepts from probability theory and stochastic processes are used to derive the number of cycles distribution (NCD), residence time distribution (RTD) and various total regional residence time distributions (TRRTDs) as well as their means and variances. Expressions for the joint distributions of pairs of these random variables are also derived as well as explicit expressions for their covariances and correlation coefficients. Two applications of the results are illustrated: one in analyzing a continuous spouted-bed coating unit and the second in using the cascade as a flexible, physically based multi-parameter flow model.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
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  • 58
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 27 (1981), S. 928-937 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The Isotherm Migration Method of numerically analyzing conduction with phase change is modified to handle surface and external resistances, appearance, and propagation of successive fronts into slabs of composite material of one or more constituents finely dispersed in a matrix, different components transforming at different temperatures. Procedures are developed for selecting temperature intervals between isotherms, initially locating isotherms by means of analytical approximations to the earliest stages, and thereafter inserting and removing isotherms as appropriate, particularly when each component gives rise to a separate front.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 59
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 27 (1981), S. 968-974 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: An improved model and solution procedure for nonequilibrium, multicomponent, two-phase, steady-state mass transfer problems are developed. Processes as diverse as packed column operation and the drying of porous solids are included. Ideas such as “HETP,” “HTU” or “mass transfer section” are avoided. “Stiff” systems appear to be handled well.
    Zusätzliches Material: 1 Tab.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 60
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 27 (1981), S. 1002-1008 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Our purpose is to give the physical conditions under which transfer of a surfactant through a fluid interface between two immiscible liquids may induce aperiodic convective motion.Adsorption-desorption rates are considered together with diffusional exchanges. New kinds of surface instabilities are then predicted.
    Zusätzliches Material: 2 Tab.
    Materialart: Digitale Medien
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  • 61
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 27 (1981), S. 1017-1020 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 62
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 27 (1981), S. 1026-1028 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 63
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 27 (1981), S. 1039-1041 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 64
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 27 (1981), S. 509-514 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 65
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 27 (1981), S. 521-523 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 66
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 27 (1981), S. 527-528 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 67
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 27 (1981), S. 526-526 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 68
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 27 (1981), S. 529-545 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The increasing demands for oil, water, and food produced in an environmentally sound manner have placed emphasis on the manner of their production, a major part of which is concerned with flow through porous media.The movement of materials through porous media is of interest in many disciplines: in chemical engineering - adsorption, chromatography, filtration, flow in packed columns, ion exchange, reactor-engineering; in petroleum engineering - displacement of oil with gas, water and miscible solvents including surface-active agent solutions and description of reservoirs; in hydrology - movement of trace pollutants in water systems, recovery of water for drinking and irrigation, salt water encorachment into fresh water reservoirs; in soil physics - movement of water, nutrients, and pollutants into plants; in biophysics - life processes such as flow in the lung and the kidney.This paper reviews the fundamentals of steady flow through porous media: it discusses the pseudotransport coefficients permeability, capillary pressure, and dispersion and relates these coefficients to the geometry of porous media. It also discusses single-fluid flow, multifluid immiscible flow, and multifluid miscible flow including the effects of heterogeneity, nonuniformity, and anisotropy of media.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
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  • 69
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 27 (1981), S. 578-587 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: This paper deals with the problem of finding, among many alternatives, the sequence of separation units that will isolate desired products from given feed at the minimum cost. Multicomponent products can be specified. An evolutionary procedure is presented. This method consists of two phases. In the first phase, a good initial structure is created by heuristic methods. In the second phase, the initial structure is successively modified by making evolutionary structural changes. This logic has been programmed on a digital computer and has been tested on several problems.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
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  • 70
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 27 (1981), S. 605-613 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Previously published data for the six binary combinations that can be formed from CO2, H2S, N2 and methanol are used to obtain parameters of the four-suffix Margules equation describing liquid solution behavior. The vapor phase is described by the Soave modification of the Redlich-Kwong equation of state. Isothermal binary data are fit well by these equations. The effects of temperature on the Margules parameters are significant and, except for N2-containing mixtures, the parameters were taken to be inversely proportional to absolute temperature.Experimental data were obtained for multicomponent mixtures of CO2, H2S, N2 and methanol. Model predictions were tested against these data. Comparisons of predicted and measured values of bubble point pressure and equilibrium vapor compositions are satisfactory.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
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  • 71
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 27 (1981), S. 613-619 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The objective of this paper is to point out the relationship between the relative gain array (RGA) and control system stability and design. Rigorous stability limits are presented for a general 2 × 2 system for several cases involving both steady state and dynamic interactions. These stability limits explicity involve the RGA. Two specific examples of interaction in distillation models are also discussed.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
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  • 72
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 27 (1981), S. 637-645 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 73
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 27 (1981), S. 654-663 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: A theoretical model is presented to describe the kinetics of nonisothermal sorption for a system in which the main resistance to mass transfer is the macrodiffusional resistance of the absorbent particle bed while the main resistance to heat transfer is the resistance at the external surface of the adsorbent sample. The model is used to interpret experimental kinetic data for the sorption of several hydrocarbons in 10X and 13X zeolite crystals. By varying the configuration of the sample bed and the size of the zeolite crystals it is shown that, for n-heptane and iso-octane in 13X, the intracrystalline diffusional resistance is negligible even in 40-μm crystals. The assumption of intracrystalline diffusion control which has been made in earlier kinetic studies of similar systems is therefore incorrect.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
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  • 74
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 27 (1981), S. 690-693 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: A general theory for examining the dynamic as well as static interactions among inputs and outputs in a multivariable control system has been developed. Both state space and frequency domain approaches are used, and at steady state the interaction equations assume the same form as the relative gain array developed by Bristol. Implications of selecting input-output pairings with regard to steady state vs. dynamic consideration are discussed. The application of the method of analysis to a distillation column control system is presented.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
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  • 75
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 27 (1981), S. 697-699 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Zusätzliches Material: 1 Tab.
    Materialart: Digitale Medien
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  • 76
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 27 (1981) 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 77
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 27 (1981), S. 733-739 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: A mathematical model and iterative correction algorithm are described for the exact solution of separation systems which contain interlinked columns in which some stages have two liquid phases and others have a vapor and liquid phase. The correction algorithm is based on Newton's method and provides for simultaneous correction of all iteration variables. The derivatives are calculated analytically from the model equations. The separation of a binary mixture which forms a heterogeneous azeotrope is analyzed. Modifications to the correction algorithm which provide for fixed condenser temperature and fixed product flows are described. The separation of butanol and water is used to illustrate the method.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
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  • 78
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 27 (1981), S. 761-767 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The kinetics of the esterification of n-butyl alcohol with acetic acid has been studied experimentally in concentrated solutions at near ambient temperature in the presence of a sulphuric acid catalyst and the rate constants for the forward and reverse reaction determined.The rate data obtained from the homogeneous system has been applied to analyse the performance of a batch-extractive reactor using n-heptane as solvent. The rate of mass transfer of the ester was found to be significant and when introduced in a model of the reaction process gave good agreement with the experimental results.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
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  • 79
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 27 (1981), S. 793-805 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: This paper deals with defining the relation between modeling of process units and controller design. In the process industries, it is often difficult to obtain accurate process models. It is shown that advanced algorithms such as dead-time compensators require more detailed process information for design than do with PI and PID controllers. A method is described to systematically evaluate the relation between process identification and controller design, stability, and performance. It is shown that conventional gain and phase margins do not provide proper safety margins for dead-time compensators and optimal controllers. Methods for safe design of dead-time compensators are derived, and the approach could be useful in a wide class of problems.To illustrate the approach presented, the design of PI controllers by conventional methods is analyzed. The conditions, as well as the exceptions, are specified in which methods such as described by Ziegler and Nichols or Cohen and Coon will give good results. It is shown that for any stable nonlinear system with an input/output function y = G*p(u), a linearized design function G′pd can be constructed and identified that guarantees stability and reasonable performance of the controller (Eqs. 21 and 22 and Figures 4-7) over a wide range of operating conditions. A rigorous framework for identifying the exceptions and understanding the reason why such methods work is presented.
    Zusätzliches Material: 15 Ill.
    Materialart: Digitale Medien
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  • 80
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 27 (1981), S. 819-823 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Electrochemical measurements of overall mass transfer rates from a single sphere have been performed in a highly turbulent liquid. The increase in mass transfer rate due to turbulence has been shown to be more important at high Reynolds number and high turbulence intensity. Various equations of correlation have been proposed between the overall Sherwood number, the Reynolds number and turbulence intensity, the simplest one being \documentclass{article}\pagestyle{empty}\begin{document}$$ Sh = 6.82\,{\mathop{Re}\nolimits} ^{0.559}\, Tu^{0.069} $$\end{document} A correct agreement has been found with previous heat or mass transfer results between a gas and a sphere.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 81
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 27 (1981), S. 851-853 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 82
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 27 (1981), S. 853-856 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 83
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 27 (1981), S. 864-866 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 84
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 27 (1981), S. 872-875 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 85
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 27 (1981), S. 876-876 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 86
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 27 (1981), S. 881-888 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: We hereby submit three different numerical methods for the solution of the multicomponent distillation model for two partially immiscible liquids. A procedure to define the real number of phases present on each stage has been developed. The proposed Newton-Raphson method allows efficient solution of problems with a large selection of the unknowns and the specification equations.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 87
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 27 (1981), S. 888-892 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Based on terLinden's (A. J. terLinden, “Investigations into Cyclone Dust Collectors,” IME Proc., 160, 233, 1949) experimental observations, a three-region model is proposed for the fluid flow in a cyclone. Within each region, turbulence is assumed to promote mixing of the suspended particles. Incorporation of this mixing concept into the three-region model allows an analytic expression for the collection efficiency of the cyclone to be developed.The theoretical result is compared with data obtained in the high temperature, high pressure exhaust from a pressurized fluidized bed combustor.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
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  • 88
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 27 (1981), S. 920-927 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: A series of seven coals were oxidized in a fixed bed reactor to determine the controlling reaction regimes during mild coal oxidation. The effects of coal porosity and particle size, reactor temperature, and oxygen partial pressure were evaluated. The results show that coal-oxygen reactions are controlled by the rate of internal gaseous diffusion for most coals, and by the rate of chemical reaction for the most porous coal of the set tested. Particle size effects also suggest internal diffusional control. Determinations of cumulative oxygen deposition indicate that surface areas several orders of magnitude greater than the superficial surface can participate in oxidation reactions, putting in doubt the applicability of the model previously derived by Kam et al. (1976a) for external mass transfer control.
    Zusätzliches Material: 12 Ill.
    Materialart: Digitale Medien
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  • 89
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 27 (1981), S. 946-951 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: A novel experimental setup allowed both the kinetics of the thermal cracking of ethane and of the coke formation to be studied over a temperature range extending from 750 to 870°C. The overall kinetics of ethane disappearance are in excellent agreement with previously reported pilot results. Coking rates are initially high but rapidly decrease to reach an asymptotic value. The initial product distribution also differs from the asymptotic product distribution. A kinetic model for the coking is derived from the experiments and used in conjunction with a set of conservation equations for the simulation of industrial ethane cracking. The predicted run length, thickness of the coke layer and evolution of the tubeskin temperatures are in agreement with industrial observations.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
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  • 90
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 27 (1981), S. 984-993 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: A theoretical model of venturi scrubber performance consisting of the governing differential equations for momentum, material, and energy exchange is solved using a Milne fourth-order predictor - Hamming corrector numerical integration procedure. The model provides for specification of the operating variables, including scrubber geometry, throat gas velocity, liquid to gas loading ratio, and collector droplet and particle-size distributions. Liquid loading ratio and gas velocity are shown to be the two most important operating variables, while the dispersity of the droplet size distribution only slightly affects collection efficiency over the operating range normally encountered. Location of the liquid injection site and length of the throat are also important design considerations. While particle collection in venturi scrubbers has typically been assumed to occur in the potential flow regime, the present results show that collection can also occur under conditions corresponding to viscous flow about the collecting droplets. The transition Reynolds number used to change from the potential to viscous flow equations affects the predicted performance.
    Zusätzliches Material: 13 Ill.
    Materialart: Digitale Medien
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  • 91
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 27 (1981), S. 1024-1026 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Zusätzliches Material: 2 Tab.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 92
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 27 (1981), S. 1035-1038 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 93
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 27 (1981), S. 1-4 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Zusätzliches Material: 1 Tab.
    Materialart: Digitale Medien
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  • 94
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 27 (1981), S. 20-25 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The trend observed on variation of the operating conditions during CO oxidation on platinum in a CSTR is as follows: stable states → simple oscillations → multipeak oscillations → stable states. Analysis of the experimental results indicates that a third or higher order system of differential equations is necessary to describe most of the observations.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
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  • 95
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 27 (1981), S. 26-32 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: A branched pore kinetic model for aqueous phase activated carbon adsorption is presented in which the carbon particle is separated into rapidly and slowly diffusing regions. The model was developed to overcome problems arising from a single rate parameter analysis and is shown to describe experimental data well. In addition to very different rates of transport in the two regions, parameters estimated by regression analysis indicated differences in the adsorptive characteristics.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
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  • 96
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 97
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 27 (1981), S. 184-192 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Some fluid mechanical information concerning mixing generation in complex flow fields can be obtained from conversion data of fast chemical reactions. Computation of such information and averages required in the procedure are presented here. Complex turbulent flow fields present deterministic-like behavior when analyzed in average sense with regard to mixing generation.
    Zusätzliches Material: 15 Ill.
    Materialart: Digitale Medien
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  • 98
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 27 (1981), S. 92-99 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The effects on the fine-crystal CSD of various surface active and ionic additives were studied for the sodium tetraborate decahydrate (borax) system. The organic modifiers used were effective at the ppm level. Surface active agents inhibited nucleation rate, while ionic additives increased nucleation. A simultaneous reduction in both the linear-crystal growth rate and the degree of polycrystalline growth was observed in both cases. These effects correlated with modifier concentration in the liquor, but not with modifier/solids ratio. Borax exhibits classical magma and RPM-dependent secondary nucleation and the results were well-correlated with a conventional power-law kinetic model.
    Zusätzliches Material: 13 Ill.
    Materialart: Digitale Medien
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  • 99
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 27 (1981), S. 234-246 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: A sudden reduction in the feed temperature to a packed-bed reactor leads to a transient temperature rise, which is referred to as the wrong-way behavior. A pseudo-homogeneous plug-flow model is used to analyze the structure of this transient behavior. The key parameters which determine the magnitude of this response are the dimensionless adiabatic temperature rise, activation energy, heat transfer capacity, coolant temperature, magnitude of temperature drop and length of the reactor. A simple expression is derived for predicing the maximum transient temperature rise.
    Zusätzliches Material: 14 Ill.
    Materialart: Digitale Medien
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  • 100
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 27 (1981), S. 255-262 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: This work presents an analysis of heat and mass transfer of extruded corn meal. Isotherm, thermal conductivity, drying and center temperature data were experimentally obtained for the cylindrically extruded product.Modeling of the drying process was made by incorporating the mechanistic and irreversible thermodynamics approaches for determining heat and mass transfer in capillary-porous media. The proposed model shows that both liquid and vapor fluxes can be expressed in terms of the same driving-forces, namely, temperature and equilibrium moisture content gradients. A search technique allowed for the evaluation of both liquid and vapor conductivities.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
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