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  • 2005-2009
  • 1985-1989  (35)
  • 1965-1969  (339)
  • 1985  (35)
  • 1967  (339)
  • Industrial Chemistry  (331)
  • Cat
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 60 (1985), S. 559-563 
    ISSN: 1432-1106
    Keywords: Cat ; Visual cortex ; Multiunit recordings ; Response variance ; Response covariance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The activity of pairs of neurons in the visual cortex (area 17) of anaesthetized, paralysed cats was recorded using two independently manipulated micropipettes. The number of spikes in the evoked responses of pairs of single neurons were analyzed for response covariance. Responses of the majority of cell pairs (83%) did not covary. Covariance was restricted to closeby neurons with distances of less than 150 μm and with identical orientation and ocular dominance preference.
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  • 2
    ISSN: 1432-0568
    Keywords: Synaptology ; Cerebellum ; Quantitative analysis ; Autoradiography ; Electron microscopy ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In a previous study observations in semithin sections of E-PTA-stained cerebellar cortex of the cat revealed differences in size of synaptic grids between the molecular and granular layer (Van der Want et al. 1984). In addition, synaptic size differences were observed between superficial and deep levels in the molecular layer. The present study was an attempt to analyze synapses in ultrathin sections of the cerebellar cortex with special emphasis on size differences of distinct types of synapses at different levels in the molecular layer. Climbing fibers were identified by means of anterograde transport of 3H-leucine injected in the inferior olive and parallel fibers were identified on account of fine structural criteria. Synaptic profiles were measured semi-automatically in the neuropil of the cerebellar cortex at the supra-Purkinje level and the subpial level. Measurements of the trace- and chordlength were obtained from random sections. The frequency distribution of the true diameters of the synapses was reconstructed with a discrete “unfolding”-procedure. The overall diameter at the superficial level was 390.2±1.5 nm, at the deep level 406.6±1.5 nin. Climbing fibers exhibited mean values of 431.9±4.7 and 461.3±4.1 nm at these levels and parallel fiber terminals mean values of 370.7±2.9 and 395.8±3.0 nm. The frequency distributions showed remarkable and statistically significant differences compared with the overall distributions observed at the superficial and the deep levels respectively. The frequency distributions of synaptic diameters at the superficial and deep levels also differ significantly. The results suggest that synapses are characterized by a specific size which might be related to the region of termination or might be determined by the afferent neuron. This is in agreement with earlier observations in E-PTA treated material.
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  • 3
    ISSN: 1432-0568
    Keywords: Lateral reticular nucleus ; Superior colliculus ; Retrograde transport of WGA-HRP ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Medium-sized and large superior collicular neurons were retrogradely labelled after small ejections of the wheat germ agglutinin-horseradish peroxidase complex in the lateral reticular nucleus of the feline medulla. The projection from the superior colliculus to the lateral reticular nucleus is bilateral with a contralateral predominance. It originates mainly from the intermediate, but also from the deep gray layer of the superior colliculus. Our observations provide evidence that the lateral reticular nucleus is an important target of tectal efferents. The findings are discussed in relation to the organization of other fiber connections of the superior colliculus.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Anatomy and embryology 171 (1985), S. 83-89 
    ISSN: 1432-0568
    Keywords: Quantitative anatomy ; Synaptic length ; Synaptic curvature ; Cerebeller cortex ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary At the supra Purkinje layer and the subpial level in the molecular layer of lobules V and VI of the cerebellar cortex of the cat, synaptic profiles were measured in ultrathin serial sections treated with either osmium tetroxide (OsO4) or ethanolic phosphotungstic acid (E-PTA). From trace and chord lengths of the intercepts of synaptic profiles the curvature and the mean caliper diameter of the synapse was calculated. In OsO4-material the curvature of synapses yielded an average angle of about 47 degrees and about 36 degrees in E-PTA material. Although these values are contrary to the assumption of a flat disc, which is commonly required in stereological procedures to estimate caliper diameter, the effect of the curvature on the estimation of the mean caliper diameter is limited. This is shown by serial reconstruction analysis of the largest diameter of synapses from maximal arc and chord length measurements at the subpial and supra Purkinje level. The results provide quantitative data concerning synaptic size, curvature and the frequency of intercepts per synapse at the subpial and supra Purkinje level in the cerebellar cortex in OsO4 and E-PTA material. In addition the advantages and disadvantages of E-PTA and osmiumtetroxide staining in quantitative analysis are discussed.
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Anatomy and embryology 171 (1985), S. 105-120 
    ISSN: 1432-0568
    Keywords: Cerebral cortex ; Corpus callosum ; Anterior commissure ; Horseradish peroxidase ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Large injections of horseradish peroxidase throughout major portions of the right cerebral hemispheres of four cats revealed extensive distributions of the neurons of origin of the corpus callosum, the anterior commissure and the hippocampal commissures in the uninjected left hemispheres. The distributions of labelled neurons were mapped by semiautomatic computer microscope. The radial and tangential neuron distributions presented here are of a higher density and greater extent than those in previously published studies based on injections of transportable label to more circumcribed areas of the cerebral cortex of the cat. Generally, commissural neurons in the cat were distributed in a bilaminar fashion with supragranular cells more numerous than infragranular cells.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 59 (1985), S. 395-403 
    ISSN: 1432-1106
    Keywords: Nucleus of the optic tract ; Direction-selective retinal ganglion cells ; Optokinetic reflex ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We have studied the physiological properties of ganglion cells in the retina of the cat. The experiments were designed to identify those ganglion cells which project to direction-selective cells in the nucleus of the optic tract (NOT), by demonstrating their antidromic activation at low threshold from an electrode in the NOT. These ganglion cells presumably provide the retinal drive to the optokinetic reflex. Altogether, 11 such ganglion cells were identified in a population of 578 cells studied. All 11 were W-cells, with slow-conducting axons. Five of the 11 had on-centre direction-selective receptive fields; the other 6 had a variety of receptive field patterns. Thus, on centre-selective cells form a much higher proportion of the retinal input to direction-selective cells in the NOT than of the overall ganglion cell population. However, their receptive field properties were too varied fully to account for the selectivity of NOT cells for horizontal stimulus movement. In summary the retinal input to the NOT appears to be formed principally or entirely by W-class ganglion cells, including many which are direction selective. It still seems necessary, however, to postulate, some non-retinal mechanism to account for all the receptive field properties of direction-selective NOT cells.
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 59 (1985), S. 463-469 
    ISSN: 1432-1106
    Keywords: Nitrous oxide ; Visual cortical cells ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The directional preferences, receptive field areas, peristimulus-time (PST) histograms and spontaneous activities of 112 feline visual cortical (area 18) cells were studied before, during, and after the administration of nitrous oxide. These cellular characteristics were altered by nitrous oxide inhalation; some quite substantially. The data indicate that the functional characteristics of cortical visual cells, such as the receptive field and the directional preference, are variable; and, among other factors, depend also on the anaesthetic administered to the animal.
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 59 (1985), S. 485-490 
    ISSN: 1432-1106
    Keywords: Vision ; Cat ; Pupil dimensions ; Luminance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The relationships between luminance and height, width or area of the feline pupil were investigated in awake, normal adult cats whose pupils were photographed over a range of light levels with the aid of electronic flash. The results are compared with previous measurements of pupil width and height in awake animals (Kappauf 1943); and with estimates of pupil width, height and area in lightly-anaesthetised cats (Wilcox and Barlow 1975). The implications of these results for retinal illumination and colour discrimination are discussed.
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 59 (1985), S. 633-635 
    ISSN: 1432-1106
    Keywords: Retinal ganglion cells ; Cat ; Optic nerve cut ; Retrograde labeling ; HRP
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary After intracranial transection of the optic nerve in cats the retinal stump of the nerve was injected with HRP. Surviving retinal ganglion cells can be retrogradely labeled at least up to 15.5 months of postoperative survival.
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 57 (1985), S. 576-584 
    ISSN: 1432-1106
    Keywords: Cat ; Lectin-conjugated horseradish peroxidase ; Lateral cervical nucleus ; Spinocervical tract ; Somatotopic termination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The labelling pattern of the feline lateral cervical nucleus (LCN) was investigated after pressure injections of lectin-conjugated horseradish peroxidase into cervical, thoracic or lumbar segments of the spinal cord. Sixteen cats received a 5–8 nl injection staining large parts of mainly the ipsilateral grey matter of a single segment. Light microscopic examination of frozen sections reacted with tetramethylbenzidine showed a somatotopic organization in the LCN. Rostral segments of the spinal cord projected mainly to rostroventral and medial parts of the ipsilateral LCN, while more caudally located segments projected to more dorsocaudal and lateral parts of the nucleus. Minor contralateral labelling with a similar somatotopic arrangement was seen in animals given cervical and lumbar injections. No significant labelling was found in the LCN of three control animals, the segmental injections of which were engaged mainly into the ipsilateral dorsal columns and the dorsolateral funiculus. Ultrastructural analysis in two animals which received multiple cervical or lumbar injections showed that about 70% of the peroxidase-positive structures in the LCN were boutons and the rest small myelinated axons. The precise termination pattern of ascending afferents to the LCN is compatible with the somatotopic organization of the other relay centres in the spino-cervicothalamic pathway.
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  • 11
    ISSN: 1432-1106
    Keywords: Cat ; Learning ; Limbic system ; Memory ; Multiple lesions ; Plasticity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Previous investigations (Irle and Markowitsch 1982a, 1983, 1984) demonstrated that triple or fourfold lesions within the cat's limbic system fail to produce learning impairments, as opposed to lesions of single or double loci, when tasks of visual reversal, delayed alternation, and active two-way avoidance were used. On the basis of these results, limbic regions of the cat's brain might be considered unessential for intact learning and mnemonic functions. Therefore, in order to obtain indisputable information on the importance of the limbic system for learning and memory, lesions of nearly all limbic core regions of the cat were performed. Ten cats received lesions of seven limbic core regions: the septum, amygdala, anterior thalamus, mamillary bodies, cingulate cortex, subicular cortex, and the hippocampus proper. Nine of these animals were tested postoperatively in the acquisition of a visual reversal task, a spatial alternation and delayed alternation task, and an active two-way avoidance task, and were then compared to the performance levels of ten control animals. The experimental animals turned out to be unimpaired in all tasks tested; the performance scores in the visual reversal and delayed alternation task and — for some experimental animals in the active two-way avoidance task even indicate a slight, though statistically insignificant, facilitation in the learning behavior of these animals. It is assumed that the learning functions underlying the tasks used were taken over by other brain regions, which, prior to massive limbic lesions, may be suppressed or otherwise inhibited. Alternatively, utilization of spared tissue in the damaged limbic regions must be considered as the possible explanation.
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  • 12
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 58 (1985), S. 427-434 
    ISSN: 1432-1106
    Keywords: Cat ; Retinal ganglion cells ; Atropine ; Optical blur ; Acuity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Two preparations were used to study the developmental effects of prolonged blurring of retinal images on the acuities of retinal ganglion cells. Five kittens were raised from three weeks to six months of age with daily administration of atropine to one eye. Another two kittens were raised from three weeks to 16 weeks with a contact lens of high refractive power fitted to one eye. Behavioural estimates of the visual acuity were made for two animals from each group. Animals of both groups demonstrated an amblyopia in the experimental eye: visual acuity varied from 1.8 to 2.5 cycles per degree compared with 6.0 to 7.5 cycles per degree when using the normal eye. The spatial resolving properties were measured for retinal ganglion cells within the amblyopic eyes of two lens-reared cats and three atropinized cats. Brisk-sustained (X) cells were recorded from along the naso-temporal division. The acuities of ganglion cells from the lens-reared cats were indistinguishable from those from normal cats at comparable eccentricities. However, for the cats raised with atropine administration, sub-normal acuities were determined for retinal ganglion cells from all regions that were studied in the experimental eye. We conclude that blur of retinal images produced by external means has no effect on the resolving power of retinal ganglion cells. The lowered ganglion cell acuities encountered with the atropinised cats must be attributable to a secondary effect of the atropine administration. Organic changes in the retinal blood vessel pattern support this contention.
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  • 13
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 61 (1985), S. 109-116 
    ISSN: 1432-1106
    Keywords: Motor cortex ; Reticulospinal neuron ; Corticobulbar pathways ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The connections between the pericruciate cortex and the medullary reticulospinal (RS) neurons were studied in anesthetized cat. Intracellular recordings were made from reticulospinal neurons and the effects of stimulating different areas of the pericruciate cortex were compared. (1) EPSPs were elicited in all the 93 neurons studied which were antidromically activated by spinal stimulation and had an IS-SD notch on the ascending limb of their antidromic spikes. According to the conduction velocity (c.v.) of the axon and the minimal EPSP latency to cortical stimulation, the neurons could be divided into two groups, i.e. fast-conducting RS neurons (FRS neurons, c.v. 〉 45 m/s) and slow-conducting RS neurons (SRS neurons, c.v. 〈 45 m/s). The minimal latencies of FRS neurons were equal to or shorter than 2 ms whereas those of SRS neurons were longer than 2 ms. (2) EPSPs with short latency (〈 2 ms) could be evoked in FRS neurons by stimulating a relatively wide cortical area including the major part of precruciate area 4 and area 6, with a central area of strongest excitatory effect located in area 4 slighthly medial to the tip of the cruciate sulcus. Stimulation of the postcruciate area 4 only produced long latency EPSPs. (3) By extrapolation from the cortical and peduncular latencies and the conducting distances it was revealed that the earliest part of the minimal latency EPSPs were monosynaptically evoked in FRS neurons and were mediated by fastconducting corticobulbar fibers. (4) FRS neurons could be excited by stimuli applied to both ipsilateral and contralateral pericruciate cortex. The influence from the contralateral cortex was slightly stronger.
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  • 14
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 57 (1985), S. 499-511 
    ISSN: 1432-1106
    Keywords: Cat ; Tensor tympani motoneurons ; Somadendritic morphology ; Intracellular HRP ; Auditory nuclei ; Tensor tympani motor nucleus of V ; Trigeminal motor nucleus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The morphology of single tensor tympani motoneurons was investigated following antidromic identification and intracellular injection of horseradish peroxidase. Eight motoneurons were selected for complete reconstruction and quantitative analysis. The mean size of tensor tympani somata (26.3±1.8 μm) make this parvocellular cluster of motoneurons below the trigeminal motor nucleus a population of the smallest cranial motoneurons yet described. Axons emerged from either the soma or a primary dendrite. They coursed dorsolaterally frequently through the trigeminal motor nucleus before looping ventrolaterally into the Vth nerve. No collaterals were observed within the brainstem. The 5 primary dendrites of each cell branched heavily and, on average, exhibited 40 terminal branches with an average tree expansion of 1262.5 μm. The dendritic arborization extended far beyond the nuclear boundaries described by the distribution of cell bodies. These data suggest that the overall membrane area for synaptic innervation is large and thus it provides morphological evidence for the hypothesis that tensor tympani motoneurons receive divergent multisensory synaptic input. The latter assumption was supported by morphological and electrophysiological evidence including close the proximity of motoneuronal dendrites to auditory (superior olivary complex) and somatosensory (trigeminal) relay centers. Since no dendrite ever entered the trigeminal motor nucleus proper the tensor motoneuron pool is distinct from the trigeminal not only in terms of soma size, location and function, but also the disposition and expansion of the postsynaptic receptive field. Based on these criteria the tensor tympani motoneuron pool should no longer be regarded as an accessory trigeminal nucleus but be recognized in its own right as the tensor tympani motor nucleus of V.
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  • 15
    ISSN: 1432-1106
    Keywords: Developmental plasticity ; Visual cortex ; Noradrenaline ; Cat ; 6-hydroxydopamine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Ten kittens had cannulas inserted into their lateral ventricles for daily injections of 6-hydroxydopamine (6-OHDA). At 5–6 weeks of age one eye was sutured shut, and one week later recordings were made from the visual cortex to assay the ocular dominance of a sample of cells. In six kittens the injections of 6-OHDA were continued until the day before recording, while in four kittens the injections were stopped around the time of eye suture, on the assumption that continued injections of 6-OHDA over several days has effects that are not specific to the noradrenaline (NA) system and that the two procedures might show different results. In all animals the concentration of NA in the visual cortex near the site of recording was reduced by approximately 90%. In all animals the ocular dominance histograms recorded from the visual cortex were shifted so that the majority of cells (83 ± 13%) were dominated by the open eye. There were no substantial differences between the two groups of experimental animals or between the experimental animals and two control animals that had cannulas implanted and ascorbate alone injected without 6-OHDA. We conclude that the concentration of NA in the visual cortex can be reduced substantially by injections of 6-OHDA into the lateral ventricle without preventing the shift in ocular dominance that usually occurs after suturing shut the eyelids of one eye.
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  • 16
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 57 (1985), S. 427-442 
    ISSN: 1432-1106
    Keywords: Cat ; Motor cortex ; Single unit activity ; Tracking ; Input switching
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In a previous study in the cat, we have reported that motor cortex neurons discharging before the initiation of an aimed forearm response (lead cells) are better timed to movement of a display (stimulus) than to the response. The present study was done to distinguish the coding of stimulus and response features in the discharge patterns of such early activity in motor cortex. Single neurons were recorded in the arm area of motor cortex in three cats performing the same pair of responses (forearm flexion and extension) but to display movements in either of the two directions by changing display polarity. The modulation of lead cell activity was contingent on the occurrence of the learned motor response and timed to the stimulus in all conditions. The majority of lead cells (88%, n = 50) fell into one of two distinct classes. In one class of neurons, force-direction (56%, n = 32), activity was contingent on a single direction of forelimb response (flexion or extension) and was thus independent of the direction of the display stimulus. The only muscles whose patterns matched the activity of this class of response-related neurons were forelimb flexors and extensors. In these neurons, the onset of modulation was timed to one or the other of the two stimuli according to the stimulus direction which elicited the appropriate response. Thus, the display-related input to these neurons varied according to the response required. In the second class of neurons, stimulus-direction (32%, n = 18), modulation was associated with a specific stimulus direction rather than the response direction. The pattern of activity of these neurons was similar to the pattern of EMG signals of shoulder and neck muscles during the different task conditions. The contraction of proximal and axial muscles corresponded to a second response elicited by the stimulus, namely attempts at head rotation towards the moving display and was independent of the conditioned forelimb response in both time of onset and direction. To test the possibility that stimulus-direction neurons participated in the control of head rotation we trained two of the animals to also produce isometric changes in neck torque in the direction of the moving display without making the forelimb response. The activity of stimulus-direction neurons was similarly modulated during performance of the neck task. By contrast, force-direction neurons examined during the neck task were either unmodulated or discharged after the neck response. These data suggest that force-direction neurons participate in response initiation and that their activity is triggered by stimuli specific for the task. The reorganization of the inputs to motor cortex is likely to result from gating mechanisms associated with behavioral set. Such neural gates could provide for the efficient transfer of any member of an array of behaviorally relevant stimuli to restricted sectors of the somatotopically organized motor areas.
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  • 17
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    Electronic Resource
    Springer
    Experimental brain research 59 (1985), S. 206-212 
    ISSN: 1432-1106
    Keywords: Lateral geniculate nucleus ; ChAT-immunocyto-chemistry ; Cholinergic pathways ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In this study we demonstrate at the ultrastructural level that both the dorsal lateral geniculate nucleus (dLGN), the visual relay of the thalamus, and the perigeniculate nucleus (PGN), the visual segment of the thalamic reticular nucleus (TRN), are densely innervated by fibres with Choline-Acetyl-Transferase (ChAT) like immuno-reactivity. These axons make synaptic contacts with interneurones considered to be inhibitory, both in the PGN and within the synaptic glomeruli of the dLGN. In addition, Chat positive terminals form intra- and extraglomerular synapses with dendrites thought to arise from relay cells. We interpret these results as evidence for direct cholinergic modulation of both relay cells and inhibitory interneurones.
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  • 18
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    Electronic Resource
    Springer
    Experimental brain research 61 (1985), S. 94-108 
    ISSN: 1432-1106
    Keywords: Cerebral cortex ; Canal-neck interaction ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Interaction of semicircular canal and neck proprioceptive inputs was studied in the cerebral cortex of awake, intact cats. Neuronal responses were recorded extracellularly in the anterior suprasylvian gyrus of the left hemisphere. Stimulations consisted of horizontal rotations in the dark applied as sinusoids or position ramps. There were three stimulus conditions: (1) Pure canal stimulation; rotation of whole body. (2) Pure neck stimulation; rotation of trunk about stationary head. (3) Canalneck interaction; rotation of head about stationary trunk. (1) We recorded 105 neurons with either Type I or Type II canal response. These showed often pronounced non-linearities such as a clear firing increase upon rotation in the “on-direction” and hardly any decrease in the opposite direction. The responses reflected mostly angular velocity, but angular position signals were also obtained. (2) In 79 neurons, either Type I or Type II neck responses were obtained. They coded either angular velocity, velocity plus position, or position. (3) Canal-neck convergence was found in 67 of 88 neurons tested. In the majority of neurons, interaction was “dantagonistic” in the sense that the canal and neck responses tended to cancel each other during rotation of the head about the stationary trunk. These neurons could signal trunk rotation in space rather than head in space or head relative to trunk. Most of the remaining neurons showed a “synergistic” interaction such that the response upon head rotation was enhanced as compared to whole body or trunk rotation. These neurons might be involved in the dual task of monitoring head rotation in space and relative to trunk. Interaction was compatible with linear summation of canal and neck inputs in 70% of the neurons. In part of these, however, the assumption had to be made that the interaction had taken place already at some stage prior to the cortical neurons investigated. The response characteristics of cortical canal neurons are discussed in comparison to vestibular nuclear neurons. Furthermore, parallels are drawn between the observed canal-neck interactions in the cortical neurons and (i) interactions of canal and neck dependent postural reflexes in the decerebrate cat, and (ii) interactions of canal and neck induced turning sensations in man.
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  • 19
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    Springer
    Experimental brain research 61 (1985), S. 117-127 
    ISSN: 1432-1106
    Keywords: Horizontal optokinetic nystagmus ; Nucleus of the optic tract ; Monocular deprivation ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 1. Six cats monocularly deprived by eye lid closure within the first week after birth showed the same deficits in the optokinetic reflex (OKR) when tested through the deprived eye as adults irrespective of whether the deprivation period was 6, 24 or 36 months. Closed loop gain (eye velocity/ stimulus velocity) during temporo-nasal stimulus movement was below 0.8 and approached zero at stimulus velocities above 20°/s. Naso-temporal stimulus movement was ineffective in eliciting OKR gain higher than 0.1 at velocities above 10°/s. 2. Different optokinetic deficits were found when the non-deprived eye was tested. In 3 cats OKR gain of the non-deprived eye was reduced with temporally directed stimulus movement when compared to normal whereas the gain of nasal OKR was uneffected. In these cats only monocular cells could be found in the nucleus of the optic tract (NOT), a pretectal cell aggregation involved in the optokinetic reflex pathway. In the other 3 cats the OKR of the non-deprived eye was not different from normal and could be elicited almost equally well in both directions. In these cats binocular cells were found in the NOT ipsilateral to the non-deprived eye. Again duration (6, 24 or 36 months) of monocular deprivation had no influence on this dichotomy. 3. In a cat with asymmetric OKR of the non-deprived eye, the removal of the visual cortex ipsilateral to the non-deprived eye produced a small but significant gain decrease for temporal OKR of the non-deprived eye but no change when the deprived eye was tested. Visual cortex lesion ipsilateral to the deprived eye in the same cat had also no effect on the deprived eye's performance but reduced nasal OKR gain for the non-deprived eye at high velocities. 4. The effects induced by long term monocular deprivation were not reversed after intensively forcing the use of the deprived eye by closing the non-deprived eye. Also enucleation of the deprived eye had no effect on the gain of the non-deprived eye. 5. These optokinetic deficits are discussed in relation to functional changes in the NOT.
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  • 20
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    Experimental brain research 58 (1985), S. 125-133 
    ISSN: 1432-1106
    Keywords: Cat ; Kitten ; Cytochrome oxidase ; Visual cortex
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The laminar pattern of cytochrome oxidase activity was studied in visual cortical areas 17,18 and 19 in adult cats and kittens, following electrophysiological determination of the boundaries of these areas in all but the youngest animals. The patterns of cytochrome oxidase staining and the cytoarchitectonic appearances of areas 17, 18 and 19 were compared. At all ages activity was especially high in the region of layers IV and VI in areas 17 and 18, and was low in all laminae in area 19. The results suggest that the degree of cytochrome oxidase activity in these regions of the visual cortex may be related to the strength and type of projection that they receive from the lateral geniculate nucleus. The cytochrome oxidase technique is a useful means of defining the 18/19 border, and may help locate the boundary between areas 17 and 18, in both adult cats and kittens.
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  • 21
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    Experimental brain research 58 (1985), S. 134-143 
    ISSN: 1432-1106
    Keywords: Cat ; Lateral geniculate nucleus ; Recurrent inhibitory system ; Variable gain regulator
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Inhibitory interactions between interneurones of the lateral geniculate nucleus (LGN) of the cat were studied with an indirect method based on intracellular recordings of synaptic responses in principal cells. Recurrent inhibitory postsynaptic potentials (IPSPs), evoked by antidromic activation of principal cell axons in the visual cortex, were depresse by a preceding stimulation of the optic tract or the visual cortex. Disynaptic feed-forward IPSPs, evoked by optic tract stimulation, were likewise depressed after cortex stimulation. The duration of the depression was in both cases about 100 ms. The effect was not due to conductance changes in the recorded principal cells or to activation of corticogeniculate fibres. The observations indicate that perigeniculate neurones, the recurrent inhibitory interneurones of the LGN, have mutual inhibitory connexions and that they also project to intrageniculate interneurones, the inhibitory cells in the feed-forward pathway to principal cells. These conclusions were supported by intracellular recordings from a few interneurones. No evidence was found for interaction between feed-forward interneurones activated from separate eyes or for a projection from intrageniculate interneurones to perigeniculate cells. The results point to an unexpected similarity in the organization of the recurrent inhibitory system of principal cells in the LGN and of spinal motoneurones. It is suggested that the recurrent system of the LGN serves as a variable gain regulator in analogy with a recently proposed model for the spinal system.
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  • 22
    ISSN: 1432-1106
    Keywords: Reticulo-hypothalamic-hippocampal system ; Cerebral blood flow ; ECoG ; Hippocampal electrical activity ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The effect of stimulation of the medial and lateral reticulo-hypothalamic-hippocampal (RHH) systems on cerebral blood flow (CBF) and electrical activity of the hippocampus and neocortex was examined in 19 encéphale isolé cats. ECoG was recorded from posterior sigmoid gyri and marginal gyri and hippocampal activity from dorsal hippocampus. Changes in hippocampal activity were evoked by electrical stimulation of RHH systems. CBF was measured by external monitoring of the clearance of 133Xe given as a single bolus in the carotid artery. Stimulation of the lateral system resulted in desynchronisation of ECoG and hippocampal activity without changes in CBF. Stimulation of the medial system elicited desynchronisation in ECoG modulated by theta-like synchrony, theta activity in the hippocampus and a 45% CBF increase. After atropine administration, low frequency, high voltage waves appeared in both ECoG and hippocampal activity, but no change in CBF was observed. During stimulation of the medial system there were no changes in the type of electrical activity but the CBF response was still preserved (increase by 50%). Stimulation of the lateral system did not change either the type of electrical activity or the CBF. The results indicate that the two systems of neuronal pathways, which mediate two different patterns of electrical response in the dorsal hippocampus but similar ECoG activity in the neocortex, elicit different CBF responses. It is argued that the alterations of electrical activity of the neocortex and hippocampus mediated by these two pathways depend on the cholinergic system, whereas the CBF changes depend on a different mechanism.
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  • 23
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    Experimental brain research 60 (1985), S. 350-362 
    ISSN: 1432-1106
    Keywords: Pretectum ; Development ; Retinal afferents ; Visual responses ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Neuronal responses in the pretectum (PT) were analyzed in 4–16 week old kittens after visual and electrical stimulation and compared with adult responses from a previous study. All three retinal fiber types projecting to the adult PT could be electrically activated in kittens from 4 weeks on. There was a dramatic reduction of response latencies to electric shocks to retinal afferents applied at the optic chiasm (OX) and optic tract (OT) in postsynaptic cells as a function of age, involving X-, Y-, and Wfibers. At four through six weeks postnatally the reduction in latency was found to be due to enhanced signal transmission at the axonal terminal region. Latency reduction continued after six weeks of life due to sharp increases in conduction velocity of the afferent fibers. Different steps in the maturation of visual response specifity were found for neurons of different functional types. Possible relationships are discussed between the development of neuronal responses of pretectal cells and the maturation of oculomotor behavior.
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  • 24
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    Experimental brain research 60 (1985), S. 363-374 
    ISSN: 1432-1106
    Keywords: Pretectum ; Development ; Cortical influence ; Receptive field properties ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The sensory corticopretectal projection in the cat and in its postnatal development were investigated combining neuroanatomical and electrophysiological techniques. The anatomical pattern of fiber termination was studied in relation to age using the anterograde HRP tracing method. Large injections were made in areas 17 and 18 of one or both hemispheres in 1–13 week old kittens and cats. Terminal label in the ipsilateral pretectum was seen only after the fourth week of life. Electrical stimulation in the same cortical areas evoked postsynaptic orthodromic excitation in 9–18% of cells at 4 weeks increasing to about 60% in the adult. In cats, but not in kittens, successful stimulation depended on the retinotopic matching of stimulation and recording sites. In adult cats a high incidence of direction and velocity tuning and a high degree of binocularity were seen in cells driven by the cortex as opposed to cells not so driven. Cortex driven cells in cats and kittens received convergent retinal input mainly via direct W-fibers, whereas cells not driven from cortex shock mainly received delayed W-fiber input. In kittens visual responses lacked sensitivity for direction and high movement velocity of patterns until 6 weeks postnatally, whereas ocular dominance distribution was not age-dependent.
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  • 25
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    Experimental brain research 60 (1985), S. 411-416 
    ISSN: 1432-1106
    Keywords: Vision ; Motion after-effects ; Cat ; Visual cortex
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Responses of striate cortical neurones to bars of optimal orientation and width, moving with fixed velocity, were recorded in the lightly anaesthetized cat. Effects of periods of pre-adaptation with square-wave gratings of variable spatial frequency and velocity, drifting continuously in each cell's preferred or null directions, were investigated. Variations of cells' directional bias and responsiveness to oriented bars were assessed in relation to the degree and time-course of pre-adaptation to drifting gratings, compared with the preceding level of firing when exposed to uniform backgrounds of the same average luminance. All cells showed some susceptibility to pre-adapting moving gratings: subsequent responses to a bar were initially depressed in the direction of pre-adaptation and, in direction-biased or bidirectional cells, were enhanced in the opposite direction, compared with bar responses following exposure merely to a uniform background. These effects were strongest and most consistent amongst standard complex cells and weakest amongst special complex cells: maximal effects were obtained with adapting gratings of optimal velocity and spatial frequency.
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  • 26
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    Experimental brain research 60 (1985), S. 1-9 
    ISSN: 1432-1106
    Keywords: Strabismic amblyopia ; Cat ; Retina ; Acuity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Experiments were carried out to determine the effects of different types of experimental strabismus on the acuities of retinal ganglion cells. Six kittens were raised from twenty-one days of age with an esotropia surgically induced by myectomy of the lateral rectus muscle and a large portion of the superior oblique muscle. The results are compared with those, previously reported, from five other cats also made esotropic, but by tenotomy of the lateral rectus. All animals tested behaviourally were amblyopic in the strabismic eye. For square wave gratings, the visual acuities were 1.0 to 2.5 cyc/deg through the strabismic eye compared with 6.0 to 7.5 cyc/deg through the non-deviating eye. The cut-off spatial frequencies were determined for 132 brisk sustained cells from five of the myectomized strabismic cats. There was a loss of approximately 20% in cut-off spatial frequency when compared with both normal and tenotomized cats. A correlate of the physiologically observed difference between the tenotomized cats and the myectomized cats was also found in the morphology of cells in the lateral geniculate nucleus. The tenotomized cats showed no evidence of cell shrinkage in laminae receiving a projection from the amblyopic eye whereas in the myectomized cats large differences were observed in cell cross-sectional areas between laminae receiving input from the amblyopic eye and those receiving input from the non-deviating eye. Together, these findings indicate that the presence of a neural deficit in the retina of strabismic cats is associated with the actual removal of extra-ocular muscle and probably has little to do with the optical quality of images arriving at the retina.
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  • 27
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    Experimental brain research 60 (1985), S. 19-26 
    ISSN: 1432-1106
    Keywords: Corpus callosum ; Binocular depth perception ; Stereoacuity ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The role of the corpus callosum in the mediation of binocular depth perception was examined by measuring monocular and binocular depth discrimination thresholds in cats which had undergone section of the corpus callosum shortly after birth. Three kittens had the posterior callosum sectioned at the age of eleven days. A fourth kitten underwent a sham operation and one additional animal served intitially as an unoperated control. Monocular and binocular depth thresholds were measured for all kittens when they were between three and five months old. Although there was some individual variability, none of the callosum-sectioned kittens showed any deficits of binocular depth perception relative to normal animals. The initially unoperated kitten had its callosum sectioned at five months and was retested following surgery. Its performance did not change from preoperated levels. Finally, the three neonatal callosum-sectioned kittens underwent section of the optic chiasm when they were six months old, causing a complete breakdown in binocular depth discrimination. The results are interpreted to indicate that although the corpus callosum may be a sufficient pathway for the maintenance of stereopsis in cat, it is not necessary.
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  • 28
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    Experimental brain research 60 (1985), S. 179-183 
    ISSN: 1432-1106
    Keywords: Area 20 ; Corticofugal connections ; Pupilloconstrictor area ; Near reflex ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Following injections of horseradish peroxidase-wheat germ agglutinin conjugate (HRP-WGA) and tritiated leucine into area 20 of the cat, terminal labeling was observed in visual areas 19, 21, the splenial visual area, the lateral suprasylvian area as well as in premotor, association and limbic related cerebral cortical regions. Labeled terminals in the subcortex were distributed in the caudate nucleus, the claustrum, the putamen, the anterior ventral nucleus, the intralaminar nuclei, the caudal division of the intermediate lateral nucleus, the lateralis posterior-pulvinar complex, the parvocellular C laminae of the dorsal lateral geniculate nucleus and the ventral lateral geniculate nucleus. In HRP-WGA preparations, retrogradely labeled somata were observed in these regions with the exception of certain subcortical structures. The projections are discussed with respect to the possible role area 20 plays in the cortical control of pupillary constriction.
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  • 29
    ISSN: 1432-2072
    Keywords: β-Carbolines ; FG 7142 ; Benzodiazepines ; Diazepam ; Ro 15-1788 ; Drug dependence ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The β-carbolines, which are potent ligands for benzodiazepine receptors, antagonize the pharmacological actions of benzodiazepines. In the cat, the stable β-carboline derivative methylamide-β-carboline-3-carboxylate, FG 7142, and the specific benzodiazepine antagonist Ro 15-1788 reversed behavioral and electroencephalographic (EEG) changes produced by a single dose of diazepam. Surprisingly, the β-carboline did not elicit signs of withdrawal when given after 22 days of a daily dose regimen of diazepam, while Ro 15-1788 precipitated an acute abstinence syndrome largely characterized by tremors, increased muscle tone, back arching, myoclonic jerks and pupil dilatation. Unlike Ro 15-1788, the β-carboline produced effects of its own such as behavioral states of arousal and fearfulness. These findings indicate that the β-carboline functionally interacts with benzodiazepine receptors in a manner unlike that seen with typical agonists and antagonists.
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  • 30
    ISSN: 1432-2013
    Keywords: Arterial chemoreceptors ; Cat ; Control of breathing ; Electrical stimulation ; Intracranial chemosensitivity ; Oesophageal pressure ; Respiration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Ventilatory responses to stimulation of chemoreceptor afferents were studied in the anesthetized, spontaneously breathing cat. Short bursts of electrical stimuli were applied, at various times in the inspiratory or expiratory phase of consecutive breaths, to the carotid sinus (CSN) and aortic nerves (AN) and to the ventral medulla (VM), and effects on tidal volume (V T), inspiratory, expiratory and cycle durationst I,t E,t tot) and in ventilation (E) were measured. The responses evoked by stimulating CSN, AN and VM were qualitatively the same, although there were quantitative differences. It was found that effects of stimulation in expiration were restricted to the expiratory phase, and vice versa for inspiration. Stimulation during both inspiration and expiration resulted in increasedV T, by increasing end-inspiratory or decreasing end-expiratory lung volume, respectively, and also increased ventilation, E. These effects were most marked in response to stimulation in inspiration. During both phases there was an increasing effect with increasing delay of the stimulus,t St, from onset of inspiration or expiration, respectively. There was a continuous increase int I, from below control to above control values, with increasingt St during inspiration and similarly fort E during expiration. Hence, the total respiratory cycle duration was shortened when a stimulus was applied early in either phase, and was prolonged, when it was applied late. The results show that stimulation of peripheral and of central chemoafferents exerts qualitatively similar effects on respiration. The central neuronal mechanisms generating both inspiration and expiration show the same changes in reactivity in the respiratory cycle.
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  • 31
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    International orthopaedics 9 (1985), S. 123-127 
    ISSN: 1432-5195
    Keywords: Hip Capsule ; Cat ; Afferent receptors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Résumé Les auteurs ont étudié les propriétés des nerfs afférents à la capsule de la hanche, chez le chat en imprimant à l'articulation des mouvements de rotation et sur des préparations de capsule isolée et ouverte en l'étirant directement grâce à un dispositif mécanique. In situ, on a trouvé deux types de nerfs afférents, les uns ayant en réponse à la rotation articulaire une étendue complète de sensibilité et les autres seulement une sensibilité limitée. Sur la capsule isolée les nerfs afférents sont indentiques en ce qui concerne le seuil et la sensibilité et on ne trouve aucun récepteur complet. On en conclut que les récepteurs de toute l'étendue de la sensibilité qui pénètrent les nerfs articulaires de la hanche sont des fibres en fuseau d'origine musculaire et non des récepteurs capsulaires. Sur ces bases et sur les résultats précédemment obtenus chez l'animal et chez l'homme, les auteurs discutent le rôle des récepteurs articulaires dans la cénesthésie et le sens des positions.
    Notes: Summary The properties of the afferent fibres from the capsule of the hip joint have been studied in the cat in situ, in relation to joint rotation, and in an isolated capsule preparation which was opened and stretched directly with an actuator. In situ two types of afferent fibres were found, those having a full range of sensitivity and others having only a limited range in response to the joint rotation. When studied in isolated tissue the afferent fibres of the capsule were uniform in threshold and sensitivities, and no full range receptors were found. We conclude that the full range receptors which enter the articular nerve of the hip are spindle afferents and not capsule receptors. On the basis of these and previous results in animals and man the role of joint receptors in kinaesthesia and position sense is discussed.
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  • 32
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    Cell & tissue research 239 (1985), S. 43-50 
    ISSN: 1432-0878
    Keywords: Centriolar antigen ; Basal body ; Immunoelectron microscopy ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary An antigen common to purported centriolar and basal body regions of a variety of cell types was previously visualized by immuno-fluorescence microscopy. The present study demonstrates the localization of the antigen relative to the defined basal body structures of ciliated tracheal cells at the electron-microscopic level. After ethyldimethylaminopropyl carbodiimide-glutaraldehyde-saponin (EGS) fixation and permeabilization, immunoferritin labeling is consistently found associated with amorphous electron-opaque material in proximity to basal bodies and their ciliary rootlets, but not with basal body microtubules themselves. This distribution pattern is distinct from that of other proteins found in the apical region of ciliated cells, such as calmodulin. It is proposed that the dense material may be analogous to pericentriolar material of centrosomes.
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  • 33
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    Cell & tissue research 240 (1985), S. 541-552 
    ISSN: 1432-0878
    Keywords: Oligodendroglia ; Neuroglia ; Perineuronal satellites ; Interfascicular glia ; Pons ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Morphology, microtopography and numerical density of oligodendrocytes were analyzed by light microscopy in the pontine gray and middle cerebellar peduncle of adult cats. The cells were selectively stained by use of the dicyanoargentate technique (Ogawa et al. 1975) that visualizes the entire cell population including perikarya and characteristic features of processes. On the basis of different microtopographical relations to neuronal perikarya and/or transversely oriented axon bundles, six groups of oligodendrocytes were separately analyzed: interfascicular, intrafascicular, perifascicular, perineuronal satellite, perifascicular-perineuronal, and “neuropil” cells. The cell morphology did not co-vary with any of these groups, but the shape of oligodendrocytes was on an average more elongated in the peduncle than in the pontine gray. The average cell density was similar in the gray and white matter (55000–56000 cells/mm3). However, 76% of the cells were concentrated near neuronal perikarya and axon bundles in a volume fraction of only 34%. Between adjacent neurons and axon bundles the cell density was even higher suggesting an additive behavior of these two topographical groups of oligodendrocytes. Axon bundles within the pontine gray contained only very few oligodendrocytes (density 6% that of the peduncle). These observations and quantitative data suggest that the perifascicular cells belong to the group of oligodendrocytes that are topographically related to axons (similar to interfascicular glia of the white matter) rather than to neuronal perikarya or neuropil.
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  • 34
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    Cell & tissue research 242 (1985), S. 399-407 
    ISSN: 1432-0878
    Keywords: Cerebral microvasculature ; Inflammatory reaction ; Polymorphonuclear leukocytes ; α-Bungarotoxin ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Postcapillary venules represent the segment of the microvasculature most vulnerable to inflammatory processes. While there is a considerable body of data on the peripheral vasculature, little is known about the primary events occurring during inflammatory reactions in cererbral blood vessels. We introduce here a model by which the migration of polymorphonuclear leukocytes through the CNS endothelial barrier can be studied. Alpha-bungarotoxin is used as a chemotactic agent and is shown, for the first time, to act by activating the complement cascade. Leukocytes migrate through the endothelium transcellularly. Two modes of migration are described: (i) a direct mode whereby the cells use temporary pores in the vessel wall as portals, and (ii) an indirect mode whereby the leukocytes leave the vascular compartment after being enveloped by and incorporated into endothelial cells. The functional implications of these findings lead us to conclude that the direct mode of migration is a causal agent in the massive breakdown of the blood-brain barrier under acute inflammatory conditions.
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  • 35
    ISSN: 1432-0878
    Keywords: Substance P ; Cardiovascular system ; Central nervous system ; Immunohistochemistry ; Mapping ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The distribution of substance P-immunoreactivity (SP-IR) in the brainstem and spinal cord of normal and colchicine-pretreated cats was analysed using the peroxidase-antiperoxidase (PAP) technique. Numerous SP-IR fibers are present in the nucleus solitarius, nucleus dorsalis nervi vagi and nucleus spinalis nervi trigemini, various parts of the formatio reticularis, substantia grisea centralis mesencephali, locus coeruleus and nucleus parabrachialis. SP-IR perikarya occur in the substantiae gelatinosa and intermedia of the spinal cord, the nucleus spinalis nervi trigemini-pars caudalis, the nucleus dorsalis nervi vagi, and the nucleus solitarius, as well as in the adjacent formatio reticularis and the medullary nuclei of the raphe. In addition, SP-IR cell bodies are located in the nuclei raphe magnus and incertus, ventral and dorsal to the nucleus tegmentalis dorsalis (Gudden), nucleus raphe dorsalis, substantia grisea centralis mensencephali, locus coeruleus, nucleus parabrachialis and colliculus superior. The results indicate that SP-IR neurons may be involved in the regulation of cardiovascular functions both at the central and peripheral level. A peripheral afferent portion seems to terminate in the nucleus solitarius and an efferent part is postulated to originate from the nucleus dorsalis nervi vagi and from the area of the nuclei retroambiguus, ambiguus and retrofacialis.
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  • 36
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    Experimental brain research 3 (1967), S. 117-134 
    ISSN: 1432-1106
    Keywords: Supraspinal effects ; Extrapyramidal pathways ; Spinal activity ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Effects of stimulation of the sensorimotor cortex on activity of the lumbosacral cord were studied in pyramidotomized cats. The following actions initiated by corticofugal volleys were found: 1. postsynaptic effects on motoneurones, mainly excitatory in flexor motoneurones and inhibitory or excitatory in extensor motoneurones, 2. facilitation of spinal reflexes to motoneurones at an interneuronal level, 3. depolarization of presynaptic terminals of group Ib and cutaneous fibres. The latencies of the earliest cortical effects on motoneurones as indicated by modification of monosynaptic reflexes or PSPs were 9–12 msec. Experiments with lesions of different spinal tracts suggest that the effects on motoneurones are mediated mainly by pathways in the ventral part of the lateral funiculus (probably reticulospinal), the facilitation of reflex transmission by pathways in the dorsal part of the lateral funiculus (probably rubrospinal) and primary afferent depolarization by both the former and the latter pathways. The strongest cortical effects were evoked by stimulation of an area around the postcruciate dimple.
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  • 37
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    Experimental brain research 3 (1967), S. 372-381 
    ISSN: 1432-1106
    Keywords: Red nucleus ; Inferior olive ; Muscle spindles ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In cats anesthetized with halothane the influence of central stimulation upon the dynamic sensitivity of muscle spindles in the flexor digitorum longus muscle was studied. One mesencephalic and one medullary region were found which caused an increase in dynamic spindle sensitivity when stimulated electrically. Histological identification of stimulating points showed these regions to be the caudal pole of the red nucleus and the inferior olivary nucleus respectively. Lesions in the olive decreased rubral effects on the spindles, indicating that the red nucleus and the olive are parts of the same system descending to dynamic fusimotor neurones. Further evidence for this point are given in a following paper (APPELBERG 1967).
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  • 38
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    Experimental brain research 3 (1967), S. 382-390 
    ISSN: 1432-1106
    Keywords: Red nucleus ; Inferior olive ; Cerebellum ; Muscle spindles ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In the preceding paper (Appelberg and Molander 1967) the caudal part of the red nucleus and parts of the inferior olivary nucleus were shown to cause increased dynamic sensitivity of muscle spindles when stimulated repetitively. The results to be presented will show that single shock electrical stimulation in the caudal part of the red nucleus evoked a field potential in the inferior olivary nucleus. This response seemed to be monosynaptically evoked and was observed only in parts of the olive where repetitive stimulation caused increased dynamic sensitivity of muscle spindles. Stimulation in the red nucleus as well as single shock stimulation in the actual part of the inferior olive also caused a potential in the vermis of the posterior cerebellar lobe. In conditioning — test experiments with the two stimuli the conditioning shock was seen to cause alternating periods of decreased and increased responsiveness in the pathway concerned. The same type of interaction was seen between two responses caused by double shock stimulation in the red nucleus. It is concluded that information from the caudal part of the red nucleus reaches dynamic fusimotor neurones in the spinal cord via a relay in the inferior olivary nucleus; an additional relay in the pathway is also predicted. The cerebellum seems to receive information about ongoing activity in the pathway but mesencephalic stimulation was seen to cause spindle effects also in decerebellated animals.
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  • 39
    ISSN: 1432-1106
    Keywords: Monosynaptic reflex ; Presynaptic inhibition ; Extensor nerve ; Spinal cord ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 1. Electrical stimulation of extensor nerves of the ankle has been used to investigate the presynaptic inhibition in a synergic monosynaptic reflex arc. 2. Depression of monosynaptic reflex response as well as increase in excitability of Ia afferent terminals in the MG (medial gastrocnemius) reflex arc is found following the conditioning stimulation of LGS (lateral gastrocnemius-soleus) nerve at Group I strength. 3. Excitability increase of the Ia terminals of the LGS nerve is also found following the conditioning stimulation of either a group of fibres of the same nerve or the MG nerve. 4. Conditioning by Group I afferent volleys from either the LGS or the PBST (posterior biceps-semitendinosus) muscles produces comparable changes in excitability of the Ia terminals from MG muscle. 5. The hypothesis is advanced that the depression of the monosynaptic reflex discharge during repetitive stimulation is mainly caused by the depolarization of the Ia afferent terminals, i.e. by presynaptic inhibition.
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  • 40
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    Diabetologia 3 (1967), S. 249-265 
    ISSN: 1432-0428
    Keywords: Spontaneous Diabetes ; Dog ; Cat ; Diabetes in dogs and cats ; Pancreas ; Islets of Langerhans ; B cells ; Insulitis ; Hyalin ; Capillaries ; Kidney ; Retina ; Microaneurysms ; Pituitary
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Résumé Les auteurs présentent une étude histopathologique de 30 chiens et de 5 chats spontanément diabétiques. — Les îlots de Langerhans et les cellules B étaient fortement diminués en nombre chez la grande majorité des chiens. Les cellules B étaient souvent dégranulées et hydropiques. Chez les chiens dont le diabète avait évolué pendant longtemps, les îlots étaient très rares et les cellules B absentes. — Chez les 5 chats spontanément diabétiques par contre, les îlots et les cellules B étaient nombreuses. Les cellules B étaient dégranulées et hydropiques chez 4 chats. Chez 1 des chats, les cellules B paraissaient normales. De nombreux îlots présentaient des dépôts de substance hyaline dans le stroma. Chez un chat, il existait une infiltration lymphocytaire très dense dans un îlot. — Ni chez les chiens, ni chez les chats, il n'a été vu de lésions glomérulaires identiques à celles de glomérulosclérose diabétique humaine. Les lésions les plus fréquentes consistaient en un épaississement des axes membraneux des touffes glomérulaires et une hypertrophie de la paroi des artérioles afférentes.— Dans les rétines des chiens diabétiques il existait une acellularité focale ou généralisée de la paroi des capillaires. Un petit nombre de microanévrysmes ont été trouvés chez 3 chiens diabétiques. L'incidence plus faible des lésions de rétinopathie vasculaire, comparativement aux diabétiques humains, s'explique probablement par la durée de vie plus courte du chien et du chat. Il est possible aussi que les capillaires rétiniens de ces animaux soient moins susceptibles de développer des lésions dégénératives. — Un degré marqué de stéatose hépatique a été observé chez beaucoup de chiens et de chats. Les surrénales étaient souvent hypertrophiées et contenaient des adénomes, mais ces lésions ne paraissent pas différentes de celles que l'on peut trouver chez des chiens et des chats non diabétiques de même âge. L'hypophyse a été prélevée chez 7 chiens. Dans 2 cas, elle contenait un adénome. Une étude cytologique plus complète des hypophyses sera publiée ultérieurement.
    Abstract: Zusammenfassung Die Autoren berichten über die Ergebnisse von Untersuchungen an 30 spontan-diabetischen Hunden und 5 spontan-diabetischen Katzen. Bei der großen Mehrzahl der diabetischen Hunde war die Zahl der Langerhansschen Inseln und der B-Zellen stark herabgesetzt. Die B-Zellen waren oft degranuliert und hydropisch. Bei Hunden mit schon lang anhaltender Krankheit waren die Inseln nur noch vereinzelt und B-Zellen überhaupt nicht mehr nachweisbar. — Im Gegensatz zu diesen Ergebnissen fanden sich bei allen 5 Katzen zahlreiche Inseln und B-Zellen. Bei 4 dieser Katzen jedoch waren die B-Zellen, wie bei den Hunden, degranuliert und hydropisch entartet. Bei einer Katze war das Aussehen der B-Zellen normal. Im Stroma der Inseln von 2 Katzen konnten starke Hyalinablagerungen nachgewiesen werden. In einem Falle zeigten die Inseln eine starke lymphocytäre Infiltration. — Weder bei den Hunden noch bei den Katzen waren typische Läsionen der Glomeruli, wie sie bei der Glomerulosklerose des menschlichen Diabetes auftreten, nachweisbar. Die häufigsten Veränderungen bestanden aus einer mehr oder weniger ausgeprägten Verdickung des mesangialen Teils der Kapillaren der Glomeruli und aus einer Hypertrophie der Wand der zuführenden Arteriolen. Bei einigen Hunden und Katzen bestanden auf chronische Pyelonephritis zurückführende Narben. — In der Retina der diabetischen Hunde waren zellenlose und funktionslose Kapillaren vorhanden, und degenerierte Pericyten (“ghostcells”) waren häufiger als bei normalen Hunden. In drei Hunden wurden einige Mikroaneurismen beobachtet. Daß diese für die Retinopathie des Diabetes typischen Läsionen beim Hund verhältnismäßig selten auftreten könnte mit der kürzeren Lebensdauer der Krankheit bei diesen Tieren zusammenhängen. Es ist jedoch nicht ausgeschlossen, daß die Retina von Hunden und Katzen weniger zu degenerativen Veränderungen neigt. — In der Leber vieler Hunde und Katzen wurde eine schwere Steatose beobachtet. In vier Hunden zeigte sich beginnende Lebercirrhose. In diabetischen Hunden und Katzen waren die Nebennieren oft hypertrophisch und enthielten Adenome, die allerdings auch bei nichtdiabetischen alternden Hunden beobachtet wurden. In 2 von 7 Hypophysen diabetischer Hunde fanden sich Adenome, über deren cytologische Untersuchung in einer späteren Veröffentlichung berichtet wird.
    Notes: Summary A histological study of 30 spontaneously diabetic dogs and 5 spontaneously diabetic cats is presented. — The islets of Langerhans and the B cells were strongly reduced in number in a large majority of the diabetic dogs. The B cells were often degranulated and hydropic. In cases of longer duration, the islets were scarce and B cells could no longer be found. — In contrast to the findings in diabetic dogs, all five cats showed numerous islets and B cells. However in 4 cats, the B cells showed complete degranulation and hydropic changes, as in the dogs. In one cat, the B cells had a normal appearance. Extensive hyalin deposits were found in the stroma of the islets in 2 cats. In one cat, an islet showed a dense lymphocytic infiltration. — No lesions identical to human diabetic glomerulosclerosis were found in any of the dogs or cats. The changes most frequently observed were a variable degree of thickening of the mesangial stalk of the glomerular capillaries, and an hypertrophy of the wall of the afferent arteriole. Scars resulting from chronic pyelonephritis, were found in a few dogs and cats. — Acellular, non-functional capillaries, with degeneration of pericytes (“ghost-cells”) were found in larger numbers in the retinas of the diabetic dogs than in non-diabetic control dogs. A very few microaneurysms could be found in 3 dogs. The lower incidence of the most typical lesions of diabetic retinopathy in dogs, as compared with the human diabetic, is probably related to the shorter duration of the disease in these animals. However, a lower susceptibility of the retina of dogs and cats to develop degenerative changes cannot be excluded. — A severe steatosis was observed in the liver of many dogs and cats. In 4 dogs, the liver showed early cirrhosis. In diabetic dogs and cats, the adrenal cortex often showed hypertrophy and contained adenomas; however, these changes have also been reported in non-diabetic aging dogs. An adenoma was found in 2 of the 7 pituitaries obtained from diabetic dogs; the cytological aspect of these adenomas and of the pituitaries will be reported in a later publication.
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  • 41
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    Springer
    Experimental brain research 3 (1967), S. 95-110 
    ISSN: 1432-1106
    Keywords: Mossy fibre pathways ; Cerebellum ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 1. Field potentials in the vermal cerebellar cortex generated by a mossy fibre volley along reticulo-, cuneo- and spino-cerebellar tracts were recorded with microelectrodes and analysed by the same procedures as was done for the mossy fibre responses in the cortex by juxta-fastigial (J.F.) and trans-folial (T.F.) stimulations in the previous paper (Eccles, Sasaki and Strata 1967a). li 3. All these results corroborate the analyses and the interpretations of the field potentials in the cerebellar cortex produced by T.F.- and J.F.-evoked mossy fibre volleys in the previous paper. 4. There have not been found electrophysiologically significant differences, as Szentágothai (1964) has suggested, between the modes of mossy fibre terminations of the reticulo-cerebellar and the spino-cerebellar systems.
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  • 42
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    Springer
    Experimental brain research 3 (1967), S. 353-367 
    ISSN: 1432-1106
    Keywords: Tectum opticum ; Movement detecting neurons ; Directional sensitive neurons ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Es wurden 80 Einheiten des Tectum opticum der Katze abgeleitet und ihre Reaktionen auf stationäre und bewegte optische Reize geprüft. Neben den Neuronen, die in ihrer Reaktionsweise retinalen Einheiten vergleichbar waren, fanden sich überwiegend (89%) Neurone, die auf bewegte optische Reize reagierten. Unter den letzteren zeigte die Mehrheit (70%) richtungsspezifisches Verhalten. Bei einigen Neuronen war in einem beschränkten Bereich von 1–7.5∘/sec die Reaktion gesetzmäßig abhängig von der Winkelgeschwindigkeit des Bewegungsreizes (Potenzfunktion mit dem Exponenten 0.67). Die rezeptiven Felder waren meist rund mit einem durchschnittlichen Durchmesser von 8.1∘ (3–22∘). 68% der Einheiten reagierten nicht auf diffusen Lichtreiz. Die Reaktionen auf nicht bewegte Punktlichtreize waren rasch adaptierend und inkonstant in ihrer Art und Stärke. In kurzen Abständen mehrfach wiederholte Bewegungsreize bewirkten bei einem Teil der Bewegungsneurone rasche Adaptation. Zwei kurz aufeinander folgende Punktlichtreize ergaben eine Reaktion, die niedriger als die Summe der Erregungen der jeweils einzeln gegebenen Lichtreize war, wenn die zeitliche Folge der beiden Reize der Vorzugsrichtung des Neurons entgegengesetzt war. Bei Reizfolgen entsprechend der Vorzugsrichtung entsprach die Gesamtreaktion der Summe der Einzelreizantworten. Dies läßt vermuten, daß die Richtungsspezifität durch unilaterale Hemmung bedingt ist.
    Notes: Summary Recordings were made from 80 single units in cat's Tectum opticum during visual stimulation with moving and stationary optic stimuli. The majority of units (89%) showed movement specific reactions, the rest behaved functionally similar to retinal or geniculate neurons. 70% of the movement specific units showed directional selective reactions. The receptive fields, as determined with stationary and moving stimuli were mostly circular with an average diameter of 8.1° (range 3–22°). Stimuli passing through the periphery of the field led to less pronounced reactions than those going through the center. In 10 out of 30 units, the relation between discharge rate and angular velocity in a restricted range from 1°–7.5°/sec could be approximated by a power function with an exponent of 0.67. Above 10°/sec irregular and unsystematic alterations of reactivity were observed. 68% of the tectal units recorded did not respond to diffuse light stimuli. The reactions to localized intermittent stationary light stimuli were mostly off (42%) or on-off-responses (19%) and were characterized by fast adaptation, change of reaction type during successive intermittent stimulation and by the absence of an antagonistic field-structure. Stimulation of adjacent points in a temporal sequence corresponding to movement opposite to the most sensitive direction of a directional specific neuron led to a reaction which was below the sum of the reaction of the two stimuli given alone. At a temporal sequence of the two stimuli such as to simulate the most sensitive direction, the resulting reaction corresponded to the sum of the reactions of both stimuli given alone. This suggests a mechanism of unilateral inhibition to be responsible for directional selectivity.
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  • 43
    ISSN: 1432-1912
    Keywords: Dopa formation ; Tyrosine hydroxylase ; Dopa decarboxylase ; Adrenal gland ; Cat ; Dopa-Bildung ; Tyrosin-Hydroxylase ; Dopa-Decarboxylase ; Nebenniere ; Katze
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Nach Injektion von H-3-Tyrosin wurde die Bildung von H-3-Dopa in verschiedenen Organen (Nebenniere, Hirnstamm, Herz, Leber, Niere, Milz, Pankreas und Blut) des Huhnes und der Katze gemessen. Die Isolierung von H-3-Dopa wurde wie folgt durchgeführt: 1. Die säurelösliche Fraktion wurde durch Papierhochspannungselektrophorese im Pyridin-Eisessig-Puffer vorgetrennt. 2. Die Tyrosin-Dopa-Bande wurde eluiert und papierchromatographisch aufgetrennt. 3. Die Dopa-Bande wurde erneut eluiert und Dopa wurde als Borat-Komplex durch Papierhochspannungselektrophorese in einem Borat-Puffer charakterisiert. Nach Hemmung der Dopa-Decarboxylase mit NSD-1034 [N-Methyl-N-(3-hydroxybenzyl)hydrazin-dihydrogenphosphat] betrug der Anteil des H-3-Dopa an der Gesamtaktivität der säurelöslichen Fraktion der Nebenniere beim Huhn 4% und bei der Katze 5%. Unter diesen Bedingungen konnte H-3-Dopa in allen anderen untersuchten Organen nicht nachgewiesen werden. Ohne NSD-1034 fand sich auch in der Nebenniere kein H-3-Dopa. Bei Versuchen an Katzen wurde die H-3-Dopa-Konzentration im venösen Blut der Nebenniere gemessen. In einigen Blutproben betrug die H-3-Dopa-Aktivität bis zu 3% der Gesamtaktivität. Nahezu die gesamte von der Nebenniere gebildete Menge an H-3-Dopa wurde an das venöse Blut abgegeben. Nur 5% des neugebildeten Dopa waren am Ende des Versuches in der Nebenniere nachweisbar. Das zeigt, daß Dopa von der Nebenniere nicht gespeichert wird. Im Blut anderer Organe fand sich hingegen kein Dopa. Die Dopa-Konzentration der Nebenniere betrug nach Blockierung der Dopa-Decarboxylase ca. 1 μg/g Naßgewebe und war ohne Hemmung 〈0,2 μg/g. Die Dopa-Neubildungsrate der Nebenniere wurde abgeschätzt aus dem H-3-Dopa-Gehalt der Nebenniere sowie aus dem zeitlichen Verlauf der H-3-Dopa-Aktivität und der spezifischen Aktivität des freien H-3-Tyrosins. Bei der Katze werden von einer einzelnen Nebenniere etwa $$\frac{{0,02{{\mu}}g}}{{\min /kg}}$$ Dopa gebildet $$\left( { = \frac{{1,2{{m\mu Mol}}}}{{\min /1{{gNebenniere}}}}} \right)$$ .
    Notes: Summary After injection of H-3-tyrosine the synthesis of H-3-dopa was measured in various organs (adrenal glands, brain stem, heart, liver, kidney, spleen, pancreas and blood) of fowl and cat. The isolation of H-3-dopa was carried out in the following way: 1. The acid soluble fraction was fractionated by high voltage paper electrophoresis in a pyridine-acetic acid-buffer. 2. The tyrosine-dopa-spot was eluated and descending paper chromatography was carried out. This system separated tyrosine from dopa. 3. The dopa-spot was eluated again, and dopa was characterized by its complex with boric acid in paper high voltage electrophoresis in a boric acid-sodium hydroxide-buffer. After inhibition of the dopa decarboxylase by NSD-1034 [N-methyl-N-(3-hydroxybenzyl)hydrazine dihydrogen phosphate] H-3-dopa represented in adrenal glands of domestic fowl 4% and in those of cats 5% of the total radioactivity. Under these conditions in all the other organs investigated H-3-dopa could not be detected. Without NSD-1034 H-3-dopa was undetectable in the adrenals, too. In experiments with cats the H-3-dopa concentration in the venous blood of the adrenals was measured. In some samples H-3-dopa represented up to 3% of the total radioactivity. Nearly the total amount of H-3-dopa formed in the adrenals was secreted into the venous blood, and only 5% of the total amount were detected in the gland at the end of the experiments. This demonstrates that dopa cannot be stored by the adrenals. We failed to detect H-3-dopa in blood from any other organ. The concentration of dopa in the adrenals was about 1 μg/g wet weight after inhibition of dopa decarboxylase and without inhibition it was 〈0.2 μg/g wet weight. The dopa synthesis rate in adrenals was calculated from the H-3-dopa activity in the gland and in the venous blood and from the specific activity of its precursor H-3-tyrosine. One adrenal of the cat synthetized 0.02 μg dopa/min·kg body weight (=1.2 mμMol/min·1 g adrenal).
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  • 44
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    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 39 (1967) 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
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  • 45
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    Chemie Ingenieur Technik - CIT 39 (1967), S. 848-851 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Um die Explosionsneigung des im Lichtbogenprozeß erzeugten acetylen-haltigen Ofengases zu verringern, wird in der Praxis Wasser in die Rohrleitungen eingedüst und nebelförmig über das strömende Gas verteilt. Durch Laboratoriumsversuche konnte nachgewiesen werden, daß der Zerfallsdruck von Acetylen beim Besprühen des Gases mit Wasser erheblich ansteigt und die Zerfallskonzentration von Acetylen im Ofengas sich zu beträchtlich höheren Werten verschiebt.
    Additional Material: 4 Ill.
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  • 46
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    Chemie Ingenieur Technik - CIT 39 (1967), S. 851-858 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Der Vorgang einer Pulvermischung wurde in einer früheren Veröffentlichung(1) als Markoff-Prozeß dargestellt. Im Sonderfall gleichen Bewegungsverhaltens der Mischgutteilchen folgen deren Ortsveränderungen dem Diffusionsmodell. Hier wird nun über weitere Untersuchungen zum Diffusionsmodell berichtet. Es wurden die Formen der rotierenden Mischelemente und die Drehzahl der Mischtrommel variiert. Die Mischgeschwindigkeit nimmt zu mit steigender Drehzahl und mit Vergrößerung der Elementfläche. Die massenbezogene spezifische Mischarbeit wächst mit der Trommellänge, dem Trommeldurchmesser und dem Füllungsgrad. Bei Mischgut mit Kornmassenunterschieden treten Entmischungen auf; nach hinreichend langer Mischzeit stellen sich stationäre Konzentrationsverteilungen ein.
    Additional Material: 14 Ill.
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  • 47
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Ungarischer Bauxit aus der Lagerstätte von Halimba wurde nach drei verschiedenen Methoden mechanisch behandelt und sein Löseverhalten in Natronlauge bei Raumtemperatur ermittelt. Außerdem wurde der Autoklavenaufschluß von mechanisch aktiviertem Bauxit unter Variation von Aktivierungsdauer, Temperatur und Konzentration der Aufschlußlauge untersucht. Die Bestimmung der Sekundärteilchengröße, Dichtemessungen sowie röntgenographische und differentialthermoanalytische Untersuchungen zeigen, daß nach einer mechanischen Behandlung grundlegende Veränderungen am Festkörper entstehen, die eine größere Reaktionsfähigkeit des Bauxits zur Folge haben. Die mechanische Bauxit-Aktivierung bringt für die heute üblichen Aufschlußverfahren wesentliche Vorteile.
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  • 48
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    Chemie Ingenieur Technik - CIT 39 (1967), S. 859-865 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Die heutigen Anforderungen an Hochleistungskraftmaschinen setzen einen optimalen Verbrennungswirkungsgrad voraus. Wesentlich beeinflußt wird dieser durch die Art der Zerstäubung und die Wirksamkeit der Durchmischung von Brennstoff und Oxidator. Im vorliegenden Bericht wird über die Zusammenhänge zwischen dem Einspritzvorgang, der Zündverzugs- und Gesamtbrennzeit und dem Verbrennungswirkungsgrad berichtet sowie über den Einfluß des Impulsverhältnisses der Brennstoff- und Oxidatorstrahlen auf den Prozeß der Durchmischung und damit auf den Verbrennungswirkungsgrad. Hochleistungsbrennkammern, an die besonders hohe Anforderungen gestellt werden, befinden sich in Raketenmotoren. Zur Stützung der theoretischen Überlegungen werden deshalb experimentelle Ergebnisse aus dem Versuchsbetrieb eines in Entwicklung befindlichen Raketentriebwerkes herangezogen.
    Additional Material: 14 Ill.
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  • 49
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    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 39 (1967) 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
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  • 50
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    Chemie Ingenieur Technik - CIT 39 (1967), S. 937-945 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Bei dem Verfahren der nichtdispersiven Ultrarot-Gasanalyse unterscheidet man zwischen Ein- und Zweistrahl-Geräten. Meßprinzip und technische Ausführung eines neuartigen Einstrahl-Gerätes werden beschrieben. An Hand der physikalischen Grundlagen werden Meßempfindlichkeit und Störeinflüsse diskutiert. Abschließend wird über technische Anwendungen bei der Gasanalyse von Rauch- und Abgasen sowie Brenn- und Synthese-Gasen berichtet.
    Additional Material: 13 Ill.
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  • 51
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    Chemie Ingenieur Technik - CIT 39 (1967), S. 945-948 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In Gegenwart eines großen SO2-Überschusses ist die quantitative polarographische COS-Spurenbestimmung in Diäthylamin/Äthanol als Grundlösung möglich, wenn das SO2 ganz oder teilweise durch Braunstein oder Silicagel gebunden wird. COS und H2S lassen sich gemeinsam bestimmen, wenn die SO2-Menge in 25 ml Grundlösung etwa 5 mg SO2 nicht übersteigt. Die quantitative polarographische Analyse von H2S-Spuren in Gegenwart eines großen SO2-Überschusses gelingt in Hydrazinhydrat/Äthanol als Grundlösung.
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  • 52
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    Chemie Ingenieur Technik - CIT 39 (1967), S. 955-963 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Die röntgenographische Phasenanalyse erlaubt im Gegensatz zur chemischen Analyse die Identifizierung der einzelnen Verbindungen einer Probe. Diese Untersuchungsmethode bringt in der Korrosionsforschung klärende Aufschlüsse über die Korrosions-mechanismen in rauchgasseitigen Rohrbelägen von Dampferzengern mit Steinkohle-, Braunkohle- und Ölfeuerungen sowie in Rohrbelägen von Müllverbrennungsanlagen. Die verschiedenen Typen der Sulfat-, Phosphat- und Vanadat-Korrosionen werden diskutiert und die bisher ermittelten Verschlackungs- und Korrosionsprodukte tabellarisch zusammengestellt.
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  • 53
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    Chemie Ingenieur Technik - CIT 39 (1967), S. 949-955 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Die physikalisch-chemischen Grundlagen einer „trockenen“ Abgasentschwefelung durch Bindung von SO2 an verschiedene Adsorptionskokse werden in einer halbtechnischen Anlage mit Festbettreaktoren und repräsentativen Öl- und Kohlefeuerungsabgasen untersucht. Das SO2 wird in zwei hintereinander ablaufenden Teilschritten, einer schnell verlaufenden Adsorption und einer langsam ablaufenden chemischen Umwandlung des adsorbierten SO2 zu H2SO4, gebunden. Die Geschwindigkeit der Oxidationsreaktion ist abhängig vom SO2-, O2- und H2O-Gehalt der Abgase, von der Beladungstemperatur, der Verweilzeit der Abgase in der Reaktorschüttung sowie von der Porengröße und der Porenverteilung der Adsorptionskokse. Die beladenen Adsorptionsmittel werden thermisch mit Inertgas regeneriert, wobei die gebildete Schwefelsäure zwischen 200 und 400°C zu SO2 und H2O unter Oxidation von festem Kohlenstoff zu CO2 zerfällt.
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  • 54
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    Chemie Ingenieur Technik - CIT 39 (1967), S. 966-971 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Radioaktive Aerosole, die in der Kerntechnik eine Gefahrenquelle darstellen können, werden hinsichtlich ihrer Größen- und Aktivitätsverteilung untersucht. Die mathematischen Zusammenhänge für die Anlagerung radioaktiver Atome und Ionen an atmosphärische Aerosole als Funktion der Teilchengröße werden abgeleitet.
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  • 55
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    Chemie Ingenieur Technik - CIT 39 (1967), S. 963-966 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Experimentell wird nachgewiesen, daß eine Staubmenge über die Änderung der Eigenfrequenz eines transversal schwingenden Bandes im Vakuum gut gemessen werden kann. Statt Entdämpfung durch Vakuum erscheint es praktischer, der Dämpfung durch elektrische Hilfsmittel entgegenzuwirken. Auf dieser Grundlage ist es wahrscheinlich möglich, ein empfindliches kontinuierliches Konzentrationsmeßverfahren für Schwebstoffe zu entwickeln, etwa mittels eines Bandes mit konstantem Vorschub und konstanter Vorspannung, dessen Eigenfrequenz laufend vor und nach einer Staubabscheidestelle gemessen und verglichen wird. Der Meßwert kann hierbei leicht registrert werden.
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  • 56
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    Chemie Ingenieur Technik - CIT 39 (1967), S. 981-985 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 57
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    Chemie Ingenieur Technik - CIT 39 (1967), S. 972-977 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Der absolute Feststoffgehalt in strömenden Gasen wird fast ausschließlich durch Absaugen und Analysieren eines Teilgasstromes bestimmt. Voraussetzung einer einwandfreien Messung nach dem Teilstromverfahren ist die isokinetische Absaugung des Teilgasstromes an für den Feststoffgehalt im Gasstrom repräsentativen Stellen. Bei nicht-geschwindigkeitsgleicher Absaugung ergeben sich Meßfehler, die mit wachsender Abweichung der Absauggeschwindigkeit von der Kanalgeschwindigkeit und der Größe der Feststoffteilchen zunehmen. Die Berechnung des Strömungsfeldes in der Nähe der Sondenöffnung ermöglicht die Bestimmung der Bewegungsbahnen der Feststoffteilchen und damit eine Aussage über die Größe des Meßfehlers. Für die nachträgliche Korrektur des Meßergebnisses wird ein einfach zu handhabendes Diagramm aufgestellt.
    Additional Material: 9 Ill.
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  • 58
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    Chemie Ingenieur Technik - CIT 39 (1967), S. 977-981 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Es werden die verschiedenen bekannten Verfahren zur Bestimmung der Teilchengröße von Aerosolen kurz beschrieben. Bei einem neuen Verfahren werden die Teilchen beliebig lange in einem elektrischen Feld „aufgehängt“, d. h. in Schwebe gehalten. Veränderungen ihrer Ladung oder Masse lassen sich aus den Stabilitätsbedingungen ermitteln. Das Verfahren ermöglicht in Kombination mit Beugungsaufnahmen durch Laserlicht auch die Untersuchung kinetischer Vorgänge im Aerosol-Zustand.
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  • 59
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    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 39 (1967), S. 1101-1106 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Es wird ein Naßwaschverfahren beschrieben, mit dem große Abgasmengen gleichzeitig von kleinen staub- und gasförmigen Verunreinigungen gereinigt werden können. Für das hier behandelte Beispiel der Entstaubung der Abgase einer Düngemittelfabrik kamen erschwerend hinzu die teilweise Löslichkeit des Salzstaubes, seine hygroskopischen Eigenschaften und die Notwendigkeit, den abgeschiedenen Staub bzw. das absorbierte Ammoniak zurückzugewinnen. Es werden zwei Verfahrensstufen angewandt, das senkrechte Aufblasen eines Freistrahles auf eine Flüssigkeitsoberfläche und der anschließende Waschvorgang in einem Rieselfilmaustauscher. Beide Verfahrensstufen arbeiten mit guten Wirkungsgraden auch als Entstauber. Das Gas konnte daher mit nur geringem Kostenaufwand gereinigt werden.
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  • 60
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    Chemie Ingenieur Technik - CIT 39 (1967), S. 1107-1111 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Theoretische und experimentelle Untersuchungen über Strömungs- und Abscheidemechanismus bei der Tropfenabscheidung mit Hilfe von Trägheitskräften führten zur Konstruktion und Optimierung eines Tropfenabscheiders. Für ein Tropfenspektrum oberhalb 10 μm konnten in einer Versuchsanlage Abscheidegrade von über 99,9% bei geringem Energieaufwand erzielt werden. Die Ergebnisse bei einer Großausführung mit einem Durchsatz von 250 000 Nm3/h bestätigen die theoretischen und experimentellen Untersuchungen.
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  • 61
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    Chemie Ingenieur Technik - CIT 39 (1967), S. 1112-1116 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Es wird ein Überblick über die Möglichkeiten und Grenzen des Vorhabens gegeben, die Mahlbarkeit spröder Feststoffe allein durch Schallgeschwindigkeitsmessungen zu ermitteln. Für ein idealisiertes Modell läßt sich ein Zusammenhang zwischen der Stabwellengeschwindigkeit und der Mahlbarkeit unter Verwendung der Mieschen Beziehung für das Gitterpotential rechnerisch nachweisen. Zur Charakterisierung der Mahlbarkeit inhomogener Feststoffe muß neben der Stabwellengeschwindigkeit auch die Feststoffstruktur bekannt sein. Es besteht eine individuelle Abhängigkeit zwischen der Art des Aufbaus eines Festkörpers und den Geschwindigkeiten der drei Schallausbreitungsarten. Sie können damit zur Strukturbestimmung verwendet werden.
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  • 62
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    Chemie Ingenieur Technik - CIT 39 (1967), S. 1116-1120 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Die Untersuchungen über die Koagulation wäßriger Ton-Suspensionen nach Zugabe von Metallsalzen als Flockungsmittel ergeben, daß man je nach dem pH-Wert zwei Mechanismen unterscheiden kann: physikalische Adsorption oder Flockung und ß-Potential-Effekt oder Koagulation. Bei der Flockung im Scherfeld nimmt die Flockenbildung mit steigendem Geschwindigkeitsgradienten zu und fällt nach Überschreiten eines Maximums wieder ab, da die Scherkräfte proportional mit dem Geschwindigkeitsgradienten ansteigen. Die Flockenbildung ist reversibel. Aus der Wechselwirkung der hydrodynamischen Kraft im Scherfeld und der van der Waalsschen Anziehungskraft läßt sich eine Beziehung für den kritischen Geschwindigkeitsgradienten herleiten. Die Festigkeit der Hydroxid-Flockung ist sehr gering.
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  • 63
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    Chemie Ingenieur Technik - CIT 39 (1967), S. 1121-1124 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Die Verfahrenstechnik findet sich in den Fortschritten der Medizintechnik besonders bei der Entwicklung künstlicher Herzen auf dem Arbeitsgebiet des Entwurfs und der apparativen Gestaltung produkt-schonender Membranpumpen bestätigt. In enger Zusammenarbeit tragen Wissenschaftler aller Fakultäten zur Entwicklung eines mechanischen „Ersatzteils“ bei, das in wenigen Jahren in der Lage sein soll, die Funktion des menschlichen Herzens voll zu übernehmen.
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  • 64
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    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Die Auflösung von Feststoffen kann durch bestimmte Verunreinigungen der flüssigen Phase behindert werden. Diese Verzögerung wurde von Mutaftschiev theoretisch begründet und für kleine Konzentrationen an Verunreinigungen experimentell bestätigt. Die Vorstellung der irreversiblen Blockierung der Grenzfläche vor allem bei größeren Konzentrationen führte zu einem Integral, dessen Lösung hier entwickelt werden konnte. Versuche zeigten aber, daß der Mechanismus der irreversiblen Adsorption der Verunreinigungen an Teilen der Grenzfläche mit Vorbehalt angesehen werden muß.
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  • 65
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    Chemie Ingenieur Technik - CIT 39 (1967), S. 1180-1187 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Eine mathematisch strenge Diskussion der Strömungsvorgänge in Schnecken mit und ohne Einfluß der Massenträgheit bildet eine Grundlage für eine systematische experimentelle Erforschung des fördertechnischen Verhaltens der Schnecken und deren optimale Auslegung. Die unter Heranziehung von dimensions-theoretischen Methoden gewonnenen Schlußfolgerungen werden durch einige experimentelle Ergebnisse belegt.
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  • 66
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    Chemie Ingenieur Technik - CIT 39 (1967), S. 1187-1190 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An Hand von hydraulischen Schaltplänen für Einzel- und Gruppenantriebe werden Auswahlkriterien für hydrostatische Rührwerkantriebe aufgestellt, die dem Entwurf, der Erweiterung oder dem Umbau von Rührwerken zugrunde gelegt werden können. Entsprechend den betrieblichen Gegebenheiten werden hier nur geschlossene Ölkreisläufe sowie eine Drehzahlsteuerung durch Fördermengenänderung an der Ölpumpe oder durch Bypass-Ölstrom erörtert.
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    Chemie Ingenieur Technik - CIT 39 (1967), S. 1351-1355 
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    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 7 Ill.
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    Chemie Ingenieur Technik - CIT 39 (1967), S. 1355-1358 
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    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 3 Ill.
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    Chemie Ingenieur Technik - CIT 39 (1967), S. 1358-1360 
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    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 5 Ill.
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    Chemie Ingenieur Technik - CIT 39 (1967), S. 1361-1362 
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    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Chemie Ingenieur Technik - CIT 39 (1967), S. 1362-1363 
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    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Chemie Ingenieur Technik - CIT 39 (1967), S. 1364-1369 
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    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 7 Ill.
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  • 73
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    Chemie Ingenieur Technik - CIT 39 (1967), S. 1401-1401 
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    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 74
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    Chemie Ingenieur Technik - CIT 39 (1967), S. 1408-1410 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
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  • 75
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    Chemie Ingenieur Technik - CIT 39 (1967), S. 209-217 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Für das Rühren in einem zylindrischen Rührgefäß mit einem konzentrisch angeordneten Zylinderrührer werden die Geschwindigkeitsverteilung, der Schubspannungsverlauf, die Trombenform und die Leistung bei laminarer Strömung berechnet. Die Leistung bei turbulenter Strömung läßt sich abschätzen. Der Vergleich mit gemessenen Leistungsdaten eines Gitterrührers zeigt gute Übereinstimmung.  -  Die Berechnung des Wärmeüberganges in Rührgefäßen ist mit dem Modell des Zylinderrührers qualitativ möglich. Eine quantitative Klärung erfordert zunächst noch Untersuchungen über die Turbulenz in Rührgefäßen, die auch von der Art des jeweiligen Rührers abhängt.
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  • 76
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    Chemie Ingenieur Technik - CIT 39 (1967), S. 218-224 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Bei Rührwerken zum Mischen zäher, ineinander löslicher Flüssigkeiten hängen Drehmoment und Rührleistung von der Rührwerksgeometrie, den rheologischen Eigenschaften des Rührguts und der Rührerdrehzahl ab. Ein Diagramm zeigt die Drehmoment- und Leistungsbeiwerte von neun Rührern in Abhängigkeit von der Reynolds-Zahl. Um die Mischwirkung der verschiedenen Bauarten miteinander zu vergleichen, kann man die zum Entfärben einer Testflüssigkeit nötige spezifische Mischarbeit als Vergleichsgröße benutzen. Photographische Aufnahmen geben die von der Rührerbauart abhängige Totzonenbildung wieder.
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  • 77
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    Chemie Ingenieur Technik - CIT 39 (1967), S. 224-231 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Es wurde die Stoffübertragung zwischen zwei flüssigen Phasen in einer Rührzelle als Funktion der Drehzahl und der Diffusionszahl gemessen. Störende Marangoni-Instabilitäten wurden dabei durch Verwendung von teilweise löslichen Zweikomponentensystemen vermieden. Je nach der Rührerdrehzahl ergaben sich drei verschiedene Bereiche für den Stoffübergang. Im ersten Bereich bei niedriger Drehzahl ist die Gravitationsstabilität der Phasen von großer Bedeutung. Bei höheren Drehzahlen sind die Hauptmengen der Phasen homogen, wobei die Grenzschicht im zweiten Bereich verdünnt und im dritten Bereich erneuert wird. Für die Stoffübergangszahl im zweiten und dritten Bereich werden Gleichungen aufgestellt, die mit den physikalischen Vorstellungen übereinstimmen.
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  • 78
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    Chemie Ingenieur Technik - CIT 39 (1967), S. 231-236 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Ausgehend von der Annahme analoger Bedingungen für den Stofftransport zwischen Feststoff und Flüssigkeit werden vergleichende Untersuchungen über das Lösen von Salzen im Fließbett und im Rührgefäß durchgeführt. In beiden Einrichtungen lassen sich ausgezeichnete Grenzzustände mit  -  auf den Leistungsbedarf bezogen  -  optimalen Stoffübergangszahlen definieren. Als Bestätigung der genannten Hypothese kann angesehen werden, daß es gelingt, diese verschiedenartigen Prozesse gemeinsam mit einer einzigen dimensionslosen Auswertung darzustellen und die optimalen Stoffübergangszahlen mit einer einzigen Bestimmungsgleichung vorauszuberechen.  -  Ein Wirtschaftlichkeitsvergleich für verschiedene, schnellaufende Rührerarten und auch für veränderte Rühreranordnung im Behälter zeigt beträchtliche Unterschiede.
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    Chemie Ingenieur Technik - CIT 39 (1967), S. 237-242 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Aus der Fließkurve nicht-Newtonscher Flüssigkeiten, gemessen in Kapillar- oder Rotationsviskosimetern, lassen sich Stoffwerte gewinnen, die zur Ähnlichkeitsdarstellung der Modelluntersuchungen von Rührwerken herangezogen werden können. Messungen des Drehmoments an Rührern in verschiedenen Flüssigkeiten zeigen jedoch, daß vor allem auch deren elastische Eigenschaften, die in der Fließkurve nicht erfaßt werden, die Rührercharakteristiken beeinflussen.
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    Chemie Ingenieur Technik - CIT 39 (1967), S. 265-268 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Die Größe der verfahrenstechnischen Anlagen, der Zwang, deren Planung in begrenzter Zeit durchzuführen und der Wunsch, wichtige Betriebsergebnisse der Anlage schon vor ihrer Errichtung zu kennen, zwingen dazu, automatisierte Planungsmethoden mit analytischen Rechnungen anzuwenden, wobei Rechenautomaten benutzt werden müssen.
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    Chemie Ingenieur Technik - CIT 39 (1967), S. 269-274 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Versuche mit dem Gemisch Äthylenchlorid/Äthylenbromid in einer hydraulisch betriebenen Druckkolonne lassen die Möglichkeiten und Grenzen der einstufigen Druckkolonne zur fraktionierten Kristallisation fester Lösungen erkennen. Zusammen mit einer vorgeschalteten Kristallisier-Rinne werden 1,34 theoretische Böden erzielt. Der notwendige Preßdruck ist vom Durchsatz abhängig. Eine pulsierte Kolbenbewegung verbessert nur den Wärmeübergang.
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    Chemie Ingenieur Technik - CIT 39 (1967), S. 282-283 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 2 Ill.
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  • 83
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    Chemie Ingenieur Technik - CIT 39 (1967), S. 275-282 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Die Zerlegung eines gasförmigen oder flüssigen Zweistoffgemisches durch selektive Absorption bzw. extraktive Destillation mit Hilfe einer zusätzlichen, selektive wirkenden Komponente kann an Hand eines allgemeinen Gleichgewichtsdiagramms nach einem modifizierten McCabe-Thiele-Verfahren einfach berechnet werden. Das Diagramm gilt für ein vorgegebenes Stoffsystem unabhängig von den verschiedenen Betriebsparametern, wie Gesamtdruck, spezifischer Lösungsmittelverbrauch, Inertgasgehalt, Kolonnendruckverlust, Zwischenkühlung und  -  mit Einschränkung  -  Temperaturbereich. Bei der Vorausberechnung des Phasengleichgewichtes im nicht-idealen Vielstoffgemisch greift man zweckmäßigerweise auf ein Verfahren zurück, bei dem nur Meßdaten der Zweistoffgemische benötigt werden.
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    Chemie Ingenieur Technik - CIT 39 (1967), S. 284-290 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In einer Kolonne von 180 mm Dmr. wurde der Druckverlust an verschiedenen Siebböden am System Luft/Wasser untersucht. Aus Versuchen an Einlochböden, die mit mehreren Flüssigkeiten betrieben wurden, konnte geschlossen werden, daß ein Ansatz, nach welchem der Gesamtdruckverlust aus der Summe von Teildruckverlusten berechnet wird, sinnvoll sei. Es gelang, dimensionslose Korrelationen zu finden, mit deren Hilfe diese Teildruckverluste darstellbar sind. Die Flüssigkeitshöhe auf den Siebböden war vom jeweiligen Betriebszustand abhängig. Sie wurde durch einen Satz dimensionsloser Kenngrößen erfaßt. Es ist möglich, mittels der gewonnenen und den bereits früher mitgeteilten Ergebnissen, den Gesamtdruckverlust zu berechnen.
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    Chemie Ingenieur Technik - CIT 39 (1967), S. 306-310 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Modellversuche und Betriebserfahrungen zeigen, daß man an Stelle der meist üblichen Zyklone in geeigneten Fällen einfach gebaute Abscheider mit kleinem Platzbedarf verwenden kann, bei denen die Abscheidung durch eine scharfe Strömungsumlenkung erreicht wird.
    Additional Material: 12 Ill.
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  • 86
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    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 39 (1967), S. 311-318 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Entgegen der bisherigen Annahme tritt in der Überlaufzentrifuge eine geschichtete Strömung auf. Die Flüssigkeit strömt in einer relativ dünnen Schicht an der inneren Oberfläche der Füllung durch die Trommel. Der konstruktiv bedingte Flüssigkeitsring zwischen dieser überströmenden Schicht und der Trommelwand wird nicht durchströmt, zeigt jedoch durch die Zähigkeit des Fluids bedingte Zirkulationen. Abhängig von den Betriebsbedingungen läuft die Drehzahl der Flüssigkeitsfüllung gegenüber der Trommel nach, auch wenn keine Einbauten vorhanden sind.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
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  • 87
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    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 39 (1967), S. 319-325 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Versuche zur Kobalt-Extraktion an einem ruhenden Tropfen und zur Auslaugung von Eisen aus Eisenamalgam in einer Rührerapparatur zeigen, daß man den Stoffaustausch an der Grenze zwischen zwei flüssigen Phasen mit Diffusionsvorstellungen nur unvollständig oder überhaupt nicht erfassen kann. In vielen Fällen treten komplizierte Überlagerungen von spontanen Grenzflächenbewegungen und chemischen Reaktionen auf. Letztere können sich nicht nur primär als geschwindigkeitsbestimmend erweisen, sondern auch durch ihre Reaktionsprodukte den Ablauf einer Extraktion entscheidend beeinflussen.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
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  • 88
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 39 (1967), S. 326-334 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Es wird der Stoffübergang bei einseitiger Diffusion und großen Partialdruckdifferenzen in der laminaren ebenen Plattengrenzschicht für den isothermen Fall berechnet. Dazu müssen die miteinander gekoppelten Differentialgleichungen des Impuls- und Stofftransportes iterativ gelöst werden. Geschwindigkeits- und Partialdruckprofile werden durch den zusätzlichen Diffusionsstrom der einseitigen Diffusion stark verändert, doch beeinflussen die Geschwindigkeitsprofile nicht den zusätzlichen Diffusionsstrom. Zur Beurteilung der Ergebnisse erweist sich die bezogene Partialdruckdifferenz als sehr geeignet. Der Stoffaustausch bei der einseitigen Diffusion wird in einfacher Weise durch Sherwood-Zahlen dargestellt, die auf ihre Werte bei kleinen Partialdruckdifferenzen bezogen sind. Die gefundene Beziehung ist auch für Systeme mit anderer Geometrie und anderen Stoffeigenschaften gültig.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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  • 89
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    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 39 (1967), S. 354-355 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 90
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    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 39 (1967), S. 341-348 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Die Abgrenzung des Zustandes der gleichmäßigen Fluidisation von dem der ungleichmäßigen, der i. a. mit Blasenbildung verbunden ist, wird als Stabilitätsproblem formuliert, wobei die Stabilität der gleichmäßigen Fluidisation gegen Störungen der Feststoffkonzentration geprüft wird. Die Rechnung erlaubt die Abgrenzung stabiler Zustände von instabilen Zuständen. Eine Stabilitätskarte für das Fließbett wird entwickelt. Die rechnerische Lösung liefert Stabilitätsgrenzen in dieser Karte, die in guter Übereinstimmung mit der bisherigen experimentellen Erfahrung stehen.  -  Schwierigkeiten bei der vergleichenden Auswertung von Experimenten an Wirbelschichten lassen sich mit der rechnerischen Lösung deuten.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 91
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    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 39 (1967), S. 349-353 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Auf Grund zahlreicher Meßergebnisse anderer Autoren wird mit Hilfe der Ähnlichkeitstheorie eine neue Gleichung aufgestellt, die es gestattet, die maximal mögliche Wärmeübergangszahl zwischen einer Wirbelschicht und einer Heiz- oder Kühlfläche zu berechnen. Wenn die zur maximalen Wärmeübergangszahl gehörige Gasgeschwindigkeit vergrößert wird, verschlechtert sich der Wärmeübergang wieder. Ferner werden Hinweise zur Auslegung von Wirbelschichten gegeben.
    Additional Material: 4 Ill.
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  • 92
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    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 39 (1967), S. 334-340 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Soll beim Abfackeln petrochemischer Abgase Ruß-Bildung vermieden werden, so ist der Flamme eine genügende Sauerstoff-Menge beizumischen. Hierzu dient als „Vergasungsmittel“ ein Gemisch aus Wasserdampf und Luft. Zur Bestimmung der wirtschaftlichsten Menge und Zusammensetzung des Vergasungsmittels bei der Verbrennung von Acetylen wird in Anlehnung an den Wassergas-Prozeß zunächst das Reaktionsgleichgewicht berechnet. Die experimentelle Ermittlung der Leucht- und Rußgrenze gibt Aufschluß über die Verweilzeit und den Impuls des ausströmenden Gases. Am wirtschaftlichsten sind Abgasfackeln mit hohem Ausström-Impuls und geringer Wasserdampf-Beimengung. Die Ausströmgeschwindigkeit wird allerdings durch die Forderung nach Stabilität und einer begrenzten Lautstärke der Flammen beschränkt. Auch in dieser Hinsicht ist ein niedriger Wasserdampf-Gehalt vorteilhaft.
    Additional Material: 14 Ill.
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  • 93
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    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 39 (1967), S. 355-356 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 94
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    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 39 (1967), S. 374-374 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 95
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 39 (1967), S. 357-364 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Kalkstein- und Zementklinker-Körner der Korngröße 0,2 bis 1 mm wurden in einem Walzenspalt mit und ohne Friktion beansprucht. Unterschiedliche Friktion wurde durch verschiedene Drehzahlen der beiden Walzen eingestellt. Es wurden Walzenpaare von unterschiedlicher Oberflächenrauhigkeit verwendet.  -  Bei beiden Stoffen ergab die Beanspruchung ohne Friktion im Bereich kleiner Abbaugrade und Ausgangskorngrößen von 1000 μm und 500 μm mehr Oberfläche als die Beanspruchung mit Friktion. Die Zerkleinerungsarbeit nahm im Bereich kleiner Abbaugrade mit steigender Friktion erheblich zu.  -  Steigende Walzenrauhigkeit bewirkte beim Zerkleinern ohne Friktion eine höhere Zerkleinerungsarbeit. Mit zunehmender Friktion kehrte sich dieser Einfluß um.  -  Die Agglomeration war bei Kalkstein im Mittel doppelt so hoch wie bei Zementklinker und bei der Beanspruchung mit Friktion wesentlich niedriger als bei Beanspruchung ohne.  -  Die Energieausnutzung nimmt bei beiden Stoffen im Bereich kleinerer Abbaugrade mit steigender Friktion sehr stark ab.
    Additional Material: 20 Ill.
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  • 96
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    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 39 (1967), S. 375-379 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Bringt man eine Flüssigkeit in einen rotierenden porösen Hohlzylinder, so strömt sie infolge der Fliehkraft durch die Wandung nach außen. Dabei wird die Flüssigkeit in Tröpfchen zerteilt. Bei richtig bemessenem Durchsatz geht die Zerteilung vorwiegend unter der Wirkung statischer Kräfte vor sich. Man erzielt dadurch ein Abtropfen der Flüssigkeit oder ein Zertropfen von Flüssigkeitsfäden zu annähernd gleich großen Tropfen. Es muß zwischen der Zerteilung benetzender und nicht-benetzender Flüssigkeiten unterschieden werden. Das Verfahren hat Aussicht, im großtechnischen Maßstab angewandt zu werden.
    Additional Material: 13 Ill.
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  • 97
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    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 39 (1967), S. 379-384 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Es wurde eine Lichtsonde entwickelt, um die Fehler zu vermeiden, die bei der üblichen Probenahme aus einem Mischer auftreten. Mit der Lichtsonde und üblicher Probenahme wurden Messungen bei Mischversuchen in einer kleinen zylindrischen Trommel und in fünf verschiedenen Mischertypen ausgeführt. Der Einfluß verschiedener Parameter, wie Füllungsgrad, Füllmethode, spezifisches Gewicht der Mischungskomponenten und Korngröße auf den Mischungsgrad bei Zweikomponentenmischungen, wurden ermittelt, um so die Leistung der Mischer miteinander vergleichen zu können.
    Additional Material: 16 Ill.
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  • 98
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    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 39 (1967), S. 395-400 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 99
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    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 39 (1967), S. 385-390 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Gegen verschiedene, in Chemiebetrieben häufig zu verarbeitende Medien, wie z. B. Salpetersäure, Essigsäure oder Flüssigkeiten, die Chlor-Ionen enthalten, ist Titan widerstandsfähiger als Edelstähle. Die Angaben der Korrosionstabellen für Titan sind jedoch nicht ohne Vorbehalt zu übernehmen, weil mangelnde Belüftung oder das Verkrusten der Titan-Oberfläche die Korrosionsgeschwindigkeit im Betrieb erheblich vergrößern können. In Essigsäure bricht die passivierende Schutzschicht des Titans zusammen, wenn die Säure vollständig wasserfrei ist. Die Ursache für das spröde Verhalten von Titan-Schweißnähten konnte noch nicht gefunden werden.
    Additional Material: 9 Ill.
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  • 100
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    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 39 (1967), S. 390-394 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In Niederdruck-Luftzerlegungsanlagen werden heute mehr und mehr Aluminium-Plattenwärmeaustauscher an Stelle von Regeneratoren verwendet. Im Betrieb als Reversing Heat Exchanger (Umschalt-Wärmeaustauscher) kann auch in den Plattenaustauschern die Gasreinigung zusammen mit dem Wärmeaustauschvorgang, der für das Gesamtverfahren ohnehin notwendig ist, gleichzeitig ablaufen. Die Plattenwärmeaustauscher haben den Vorteil, daß auch im Umschaltbetrieb fast die Hälfte der ausströmenden Gase ohne Verunreinigung durch Luft, Kohlendioxid und Wasser entzogen werden können.
    Additional Material: 8 Ill.
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