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  • 1975-1979  (5,587)
  • 1965-1969  (4,530)
  • Inorganic Chemistry  (7,960)
  • Computational Chemistry and Molecular Modeling  (991)
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  • 1
    ISSN: 1435-1463
    Keywords: Cat ; electrical stimulation ; serotonin ; splanchnic nerves ; substance P
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The blood levels of serotonin (5-HT) and substance P (SP) in the portal vein were studied after splanchnic nerve stimulation in the cat. The portal levels of both substances were studied before, during and after splanchnic nerve stimulation. There was a twofold increase in 5-HT during stimulation whilst the SP concentration remained unchanged. These results suggest that the nervous control of the amine release into the portal stream and the mechanism that regulates the release of the polypeptide is not the same.
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 34 (1979), S. 273-286 
    ISSN: 1432-1106
    Keywords: Stimulus velocity ; Single cell responses ; LGN ; Area 17 ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Neuronal responses to moving visual stimuli were recorded in the lateral geniculate nucleus (LGN) and area 17 of cats. Response duration (DE), number of spikes (NT), and mean frequency (FM) were estimated from the response histograms and analysed for their dependence on stimulus velocity. In the LGN, for about 2/3 of cells these response parameters changed monotonically with velocity up to about 100 °/s. In 1/3 of the cells, the response frequency was tuned to velocity. The speed at which individual cells reached a peak or plateau firing rate was correlated with their receptive field size. In area 17, most neurones were tuned to velocity. Nine out of 59 cells were insensitive to stimulus speed in that they responded equally well at stimulus velocities up to about 10 °/s. The results suggest that at higher levels in the nervous system information about velocity is represented in discrete groups of neurones. It is pointed out that different response parameters may be relevant for different perceptual phenomena associated with movement. The significance of integrational properties and lateral inhibition of nerve cells for the development of complex response properties is discussed.
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  • 3
    ISSN: 1432-1106
    Keywords: Thermoreceptors ; Gastro-intestinal tract ; Vagal nerve ; C Fibres ; Cat ; Thermorecepteurs ; Tractus gastro ; Intestinal ; Nerf vague ; Fibres amyéliniques ; Chat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Résumé Chez des chats anesthésiés, des décharges sensitives vagales ont été enregistrées dans le ganglion plexiforme à l'aide d'électrodes extracellulaires en verre. Nous avons trouvé au niveau de l'antre et du duodénum, des récepteurs toniques, activés par des solutions chaudes (38–51 ° C avec un optimum à 46–49 ° C) ou froides (36–10 ° C avec un optimum à 12–10 ° C). Ces récepteurs ne répondent ni aux stimulus mécaniques (compression et distension des viscères), ni aux stimulus chimiques (perfusion avec des solutions glucosées ou acides). Ces récepteurs n'appartiennent donc pas au groupe des récepteurs polymodaux, mais ils doivent être considérés comme de véritables thermorécepteurs spécifiquement sensibles au chaud ou au froid. Les thermorécepteurs de la région gastro-duodénale sont connectés à des fibres vagales amyéliniques (vitesse de conduction: 0,8–1,4 m/s). Par ailleurs, le rôle éventuel des thermorécepteurs vagaux de la région gastro-duodénale dans la régulation de la motilité digestive a été recherché. En dérivant simultanément l'EMG en plusieurs points du tractus gastro-duodénal, il a été possible de démontrer que les stimulations froides et chaudes du duodénum, qui mettent en jeu les thermorécepteurs, provoquent une inhibition de l'activité électrique de l'antre. Les modifications persistent apèrs bisplanchnectomie, mais disparaissent complètement après bivagotomie. A partir de ces faits, nous en avons conclu que les thermorécepteurs vagaux sont impliqués dans la régulation nerveuse de la motilité gastro-duodénale.
    Notes: Summary In anaesthetized cats, sensory vagal units were recorded in the nodose ganglion by means of extracellular glass microelectrodes. In the antrum and the duodenum we have found receptors tonically activated by warm (38–51 ° C with an optimum at 46–49 ° C) or cold (36–10 ° C with an optimum at 12–10 ° C) solutions. These receptors did not respond to mechanical stimuli (compression and distension of the viscera) and to chemical ones (perfusion with glucose and acid solutions). Thus they did not belong to polymodal type, but they must be considered as true thermoreceptors, specifically sensitive to warm or cold stimulations. The gastro-duodenal thermoreceptors were connected to non-medullated vagal fibres (conduction velocity: 0.8–1.4 m/s). On the other hand, the role of the gastro-duodenal vagal thermoreceptors in the regulation of the digestive motility was studied. By using several electromyographic recordings, it was possible to show that the cold and warm stimulations of the duodenum which elicited thermoreceptor responses, induced an inhibition of the electrical activity of the antrum. The changes persisted after bisplanchnectomy, but disappeared completely after bivagotomy. From these facts it was concluded that the vagal thermoreceptors were involved in the nervous regulations of the gastro-duodenal motility.
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  • 4
    ISSN: 1432-1106
    Keywords: Cooling ; Ventrolateral thalamic nucleus ; Pyramidal system ; Reaction time ; Ballistic movement ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Five cats were trained to perform a forelimb ballistic flexion on a reaction time paradigm including an upper limit of about 400 ms for reinforcement (food pellets). They were implanted with a cyrogenic probe thermically insulated, except at the tip, by a vacuum jacket (outer diameter, 1.1 mm). Four cats had the probe inserted into the ventrolateral thalamic nucleus (VL), contralateral to the moving limb. During cooling they showed increased reaction times, which remained constant throughout daily sessions performed during many weeks, independent of the foreperiod but varying from 25 to 100 ms according to the subject. The temperatures used to upset the reaction times varied from +10 ° C to −8 ° C, depending on the localisation of the probe and on the insulation of the silver tip used to prevent nervous tissue reaction, but for each subject the reaction times always increased when the temperature was lowered. The fifth cat, with a probe inserted between VL and the Centre Median, showed a decrease of reaction times on cooling to 0 ° C and an increase of the reaction times for a cooling at −10 ° C. For one of the four cats with a probe properly inserted into the VL, strain-gauges were stuck on the lever to measure the latency of the decrease of the pressure exerted by the subject when the subject initiated the forelimb flexion in response to the CS. Reaction times and latencies of pressure changes were closely correlated with the movement onset, and they were equally delayed during cooling. This result demonstrates that it is not by slowing down movement velocity that reaction times are upset during VL cooling but by delaying the movement onset.
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  • 5
    ISSN: 1432-1106
    Keywords: Retractor bulbi motoneurones ; Accessory abducens nucleus ; 6th nerve ; Oculomotricity ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Motoneurones innervating the retractor bulbi muscle in the cat have been identified by retrograde labelling with horseradish peroxidase, by intracellular recording and by intracellular staining with horseradish peroxidase. Their somata are found in an accessory abducens nucleus, analogous to that described in some other species, which consists of a narrow column of cells situated in the lateral tegmental reticular field, above the superior olive and medial to the facial nerve. This column of cells extends over approximately 1.5 mm from P 5.5 to P 7. The retractor bulbi motoneurones number from 80 to 120 and have large, elongated somata which give rise to five or six major dendrites. Their axons cross the reticular formation in a dorso-medial direction to pass through the principal abducens nucleus before turning to leave the brain stem in the 6th nerve. Antidromic latencies ranged from 0.4 to 0.7 ms. Some retractor bulbi motoneurones could also be activated antidromically by stimulation of the lateral rectus muscle nerve.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 35 (1979), S. 25-36 
    ISSN: 1432-1106
    Keywords: Retinal ganglion cells ; Cat ; Contrast reversal stimulus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A contrast reversal (alternating phase) stimulus was used to study the responses of 150 retinal ganglion cells from 15 adult cats. Because the majority of the cells did not show perfect linear spatial summation, a ratio of the firing rates at two time periods was used to express the degree of nonlinearity. Y-cells showed a high degree of nonlinearity, and their mean null ratio was significantly lower than that of X-cells. With the stimulus at the null position, X-cells had an unmodulated discharge rate which was significantly higher than maintained activity, while the firing rate of Y-cells was lower than maintained activity. With the stimulus placed at an eccentric position in the receptive field, X-cells responded in a sustained manner, while Y-cells respond transiently. Because of these observations, we conclude that X-cells correspond to the sustained cells, while Y-cells correspond to the transient cells.
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 35 (1979), S. 161-175 
    ISSN: 1432-1106
    Keywords: Cerebral cortex ; Superior colliculus ; Cat ; Horseradish peroxidase method
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The retrograde labeling of cortical neurons with horseradish peroxidase (HRP) was used to investigate the morphological features of neurons in various cortical areas projecting to the superior colliculus in the cat. Corticotectal cells were found to be labeled in layer V of the entire cerebral cortex. The number of labeled cells and their locations varied according to the sites of injections of HRP in the colliculus. Most of the Corticotectal cells identified in the present study were small (9–20 μm in diameter, 66%) and medium (20–40 urn, 30%) pyramidal neurons and only 4% of them were large (more than 40 μm). The labeled cells, 261 in total number, had somal diameters of 20.8±8.0 μm (mean and SD). The range of sizes of the labeled neurons was different in different cortical areas. For example, the labeled neurons in the Clare-Bishop area had a greater proportion of large diameter cells than in other areas. The present findings are largely in agreement with the previous data of anterograde degeneration methods with respect to the topographical correlation of the Corticotectal projections. However, in some cortical areas, e.g., the sensorimotor and the first visual (area 17) cortex of the lateral surface of the hemisphere, relatively small numbers of Corticotectal neurons appear to have been labeled by retrogradely transported HRP. The sparsity of the labeled neurons in certain cortical areas may reflect the existence of Corticotectal neurons with axon collaterals supplying brain structures other than the superior colliculus.
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 35 (1979), S. 269-285 
    ISSN: 1432-1106
    Keywords: Cerebral cortex ; Pontine nuclei ; Cat ; Horseradish peroxidase method
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Horseradish peroxidase (HRP) injections in various portions of the cat pontine nuclei resulted in retrograde labeling of neurons in layer V of the ipsilateral cerebral cortex. Corticopontine neurons, pyramidal in type, have been found to be labeled in the entire cortex, confirming the previous findings of anterograde degeneration studies. Most (91%) of the labeled cells were 14–26 μm in diameter (mean 19.4±4.5 μm SD). Small (10–20 μm) and medium (20–40 μm) cells represent 51.5% and 47.7%, respectively, of the total number of the labeled neurons. The populations of the neurons of various sizes were almost identical in different cortical areas, and were different from the populations of corticoreticular and corticospinal cells. Corticopontine cells were well labeled in experimental cases of 3-days' survival time, confirming the topographical organization established previously by degeneration studies for this projection system. However, in cases of shorter survival time (20–27 h), the number of labeled neurons was very small. The relative paucity of labeled Corticopontine neurons in the sigmoid and lateral gyri is discussed with reference to other cortical descending neurons (e.g., the corticotectal, corticoreticular and corticospinal) which have hitherto been identified morphologically as well as physiologically.
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 35 (1979), S. 395-406 
    ISSN: 1432-1106
    Keywords: Cat ; Spinal cord ; Phrenic motoneurons ; Neuron geometry ; Horseradish peroxidase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Cat phrenic motoneurons, labeled by intradiaphragmatic injection of horseradish peroxidase, formed a tight cluster in the most ventral portion of the ventral horn in lamina IX of the lower cervical cord. Cell counts were symmetrically distributed for 17 to 21 mm along the longitudinal axis of the cord with a unimodal peak at the junction of segments C5 and C6. The phrenic nucleus was bilaterally organized on either side of the cord with anatomical symmetry and in no case was there evidence for the crossing of phrenic axons in the cord. Assessment of cellular geometry and intercellular relationships demonstrated that phrenic cell diameters approximated a normal distribution with a single peak at 26 μm while longitudinal cell lengths averaged 76 μm. Cells of different size were mixed randomly at all levels of the nucleus. The minimum distance between cells was about 10 μm and the maximum cell packing density approached 2 cells per 106 μm3. The results confirm the location of the cat phrenic nucleus, extend the knowledge of phrenic motoneuronal geometry, and provide an anatomical basis for the understanding of recruitment and synchronization phenomena within the phrenic nucleus.
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 35 (1979), S. 465-477 
    ISSN: 1432-1106
    Keywords: Cat ; Monkey ; Lateral geniculate nucleus ; Visual nondominant suppression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We have studied the suppression of firing in single LGN cells of cat and monkey in response to visual stimulation of the nondominant eye. In the cat LGN most of the cells of each of the main laminae show this nondominat suppression. X cells having their dominant input from the ipsilateral eye were suppressed to a significantly greater degree than any other cell type in the cat LGN. In the monkey LGN nondominant suppression was absent in all 19 X-like cells studied, whereas 6 of 21 Y-like cells showed nondominant suppression. Thus nondominant suppression is present in the magnocellular laminae of the monkey LGN, where the Y-like cells are found, but appears to be absent from the parvocellular laminae, where the X-like cells are found.
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  • 11
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 35 (1979), S. 479-494 
    ISSN: 1432-1106
    Keywords: Thermosensitivity ; Lesions ; Spinal cord ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The behavioural thermosensitivity of cat paws was examined before and/or after restricted uni- and/or bilateral lesions had been made in the spinal cord between the first and fifth cervical segments. Unilateral lesions of the lateral funiculus, which involved at least its whole width at the level of the central canal, reproducibly were found to interfere with the contralateral sensitivity for temperature increases and/or decreases. No corresponding thermosensory deficiencies were found after unilateral lesions involving the ventral spinal quadrant or the dorsal funiculus. Various bilateral and combined lesions were made, but no cat ever developed thermoanaesthesia. The bilateral lesions included bilateral transections of: the middle parts of the lateral funiculi, the dorsal halves of the lateral funiculi, the dorsal funiculi, and the ventral spinal half. Most of our knowledge about peripheral behavioural thermosensitivity after spinal cord injury is based on observations of human patients, especially after anterolateral chordotomies. The present finding of contralateral thermosensory deficiencies after lesions of the middle part of the lateral funiculus fits with some of the clinical reports. The present failure to cause thermoanaesthesia, on the other hand, is inconsistent with the theory of a single ascending spinal pathway for behavioural thermo-sensitivity, which has emanated mainly from the clinical observations.
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  • 12
    Electronic Resource
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    Springer
    Experimental brain research 35 (1979), S. 495-510 
    ISSN: 1432-1106
    Keywords: Pretectal nuclei ; Superior colliculus ; Visual response pattern ; Retinal input types ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Single unit recordings from 220 units were obtained from the nuclei praetectalis anterior (NPA) and posterior (NPP) of 30 immobilized, anesthetized cats. Quantitative analysis of pretectal (PT) visual activity was mainly based on recordings from the NPP. For comparison, 160 collicular (CS) neurons were studied. A strong sensitivity for moving objects was evident in both samples. The following main types of PT activity were categorized: (A) slow movement, direction-selective units (21%); (B) slow movement, nondirection-selective units (19%); (C) units nonselective for stimulus velocity and direction (24%); (D) jerk movement selective, nondirection-selective units (36%). Latency measurements following single shocks to optic chiasm (OX) and tract (OT) showed mainly slow conducting fiber input to the PT and CS which can be divided into two different groups by conduction properties and synaptic delay: direct W-input and delayed W-input. Fast Y-fiber input of both types, direct and indirect, was recorded at both sites, PT and CS.
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  • 13
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    Springer
    Experimental brain research 36 (1979), S. 191-194 
    ISSN: 1432-1106
    Keywords: Hypercomplex cells ; Area 18 ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Single unit recording has revealed the same orientation sensitive cell classes in cat area 18 as are to be found in area 17. These include particularly the various types of hypercomplex cell belonging to the S, C, and B cell families.
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  • 14
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    Springer
    Experimental brain research 36 (1979), S. 285-300 
    ISSN: 1432-1106
    Keywords: VL nucleus ; Single units ; Reaction time ; Movement initiation ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Unrestrained cats performed ballistic forelimb flexion movements triggered by an auditory stimulus (CS) on a simple reaction time (RT) paradigm. During the variable foreperiod the subject was required to hold down a lever and to release it on presentation of the CS. The RTs ranged from 200 to 300 ms. The activity of single neurons of the ventrolateral nucleus of the thalamus (VL) was recorded bilaterally. More than 40% of the 166 units recorded in the VL contralateral to the performing limb presented, after the CS, changes of activity with a latency less than 100 ms and were classified into three types: (1) Twenty-five units had a short latency transient increase of activity 10 to 30 ms after the CS, followed by a longer increase or decrease in activity. Short latency increase as well as subsequent increase of the firing rate were not correlated to the RTs. (2) Twenty-nine units showed a 40–60 ms latency increase of activity which lasted long enough to continue during the forelimb movement. These units displayed a correlation between the RTs and the mean firing rate measured in the 40–100 ms period after the CS. The more the cells were activated, the shorter the RTs. (3) Fifteen units presented a reciprocal pattern of discharge with respect to the type (2) units. The firing rate decreased with latencies ranging from 20 to 90 ms after the CS. Only 14,5% of the 96 units recorded in the VL ipsilateral to the performing limb presented changes of activity starting in the 100 ms period following the CS. Background firing levels as well as phasic activity were rather low compared to those observed contralaterally. Sixteen units showed burst activity while the cat was performing but burst pattern was not time-related to the task. In an unconditioned animal, a very low level of activity and an absence of modulations were observed in both VLs.
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  • 15
    Electronic Resource
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    Springer
    Experimental brain research 37 (1979), S. 41-47 
    ISSN: 1432-1106
    Keywords: Eye alignment ; Cat ; Visual experience ; Maturation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In the developing kitten, the alignment of the pupils changes from strongly divergent to almost parallel. The visual axes, however, seem to stay almost parallel throughout this period. The influence of early visual experience on this development is examined in the present study. The results suggest that the development of eye alignment is not controlled by visual experience, but depends on maturational processes, and that normal visual input serves only to halt these processes at the appropriate time.
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  • 16
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    Springer
    Experimental brain research 37 (1979), S. 177-181 
    ISSN: 1432-1106
    Keywords: Cat ; Autoradiography ; Abducens nucleus ; Primary vestibular fibers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Primary vestibular projections to the ipsilateral abducens nucleus were found in cats by injecting anterograde tracer substances (radioactive proline and fucose) into Scarpa's ganglion. Labelling was observed in the rostral and middle portion of the abducens nucleus.
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  • 17
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    Springer
    Experimental brain research 37 (1979), S. 405-416 
    ISSN: 1432-1106
    Keywords: Cerebellum ; Purkinje Cells ; Splanchnic mechanoreceptors ; Cat ; Cervelet ; Cellules Purkinje ; Mécanorécepteurs splanchniques ; Chat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Résumé Les activités simple et complexe de cellules de Purkinje du cervelet du Chat (zone vermienne des lobules V et VI) ont été enregistrées au moyen de microélectrodes extracellulaires. Ces réponses étaient obtenues par stimulation de différents types de mécanorécepteurs du tractus gastro-intestinal: récepteurs musculaires connectés à des fibres C, récepteurs péritonéaux de mouvement connectés à des fibres Aγδ ou B, corpuscules de Pacini connectés à des fibres Aβ. Les caractéristiques des fibres splanchniques projetant sur cette aire cérébelleuse ont été définies. Des convergences splanchno-somatiques, splanchno-viscérales et splanchno-corticales ont été mises en évidence.
    Notes: Summary Climbing and mossy fibre activity in Purkinje cells of cat cerebellum (vermis part of lobules V and VI) were recorded by means of extracellular microelectrodes. Responses were obtained by stimulation of different types of mechanoreceptors in the gastro-intestinal tract: muscular receptors connected with C fibres, peritoneal movement receptors connected with Aγδ or B fibres, Pacinian corpuscules connected with Aβ fibres. The characteristics of the splanchnic fibre projections on this cerebellar area were defined. Splanchno-somatic, splanchno-visceral, and splanchno-cortical convergences were demonstrated.
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  • 18
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    Springer
    Experimental brain research 37 (1979), S. 609-613 
    ISSN: 1432-1106
    Keywords: Orientation subunits ; Visual cortex ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The orientation domain in the cortical visual areas of anesthetized cats has been investigated by employing the 14C-Deoxyglucose technique (Sokoloff et al., 1977). Orientation subunits (OS) are seen in the first (V1), the second (V2) and the third visual area (V3) as well as in the visual areas of the suprasylvian sulcus. In the latter regions OS are less elaborated than in V1, V2, and V3. The OS are continuous through all cortical layers; in V1 however, only weak label is detected in layer 4C. In V1, V2, and V3 the width of the OS is about 0.4 mm and the average distance between two OS centers is 0.9 mm. The spatial pattern of the OS seems to be more regular in the visual field periphery than in regions representing the vertical meridian.
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  • 19
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    Anatomy and embryology 155 (1979), S. 323-331 
    ISSN: 1432-0568
    Keywords: Telencephalon ; Choroid plexus ; Lateral ventricle ; Blood vessels ; Micro Corrosion cast ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Corrosion casts of the complete vascular network of the choroid plexus of the lateral ventricle in the cat brain were studied in SEM using the injection-replication method. The villi of this plexus are located only on its supero-anterior and infero-posterior parts, being most densely packed in the former region, close to the interventricular foramen. The capillaries of the villi display small nodular thickenings, which suggest the presence of small, sinusoidal dilatations. The main vessel supplying the plexus with blood is the anterior choroidal artery. The plexus is also characterized by a particularly rich venous network, which is drained by a prominent (main) choroid vein. The vascular organization of the choroid plexus of the lateral ventricle in cat is compared to that of the corresponding plexuses in other mammals.
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  • 20
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    Acta neuropathologica 48 (1979), S. 55-58 
    ISSN: 1432-0533
    Keywords: Lafora-like bodies ; Morphogenesis ; Glycogen metabolism ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Lafora-like bodies in an 8-year-old cat were studied light and electron microscopically and histochemically. In addition to Lafora-like bodies composed of branching filaments, glycogen granules and electron-dense materials, abnormal accumulations of glycogen granules attracted attention. The most remarkable features were the developmental processes of the branching filaments originating directly from glycogen granules. Lafora-like bodies in the present study showed ultrastructural, histochemical, and enzymatic similarities to those described in the previous reports in Lafora's disease, glycogenosis and other cases. From these results, a certain disturbance of the glycogen metabolism is considered to be probably related to the productive mechanism of Lafora-like bodies.
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  • 21
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    Experimental brain research 34 (1979), S. 197-200 
    ISSN: 1432-1106
    Keywords: Claustrum ; Visual cortex ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Visual cortex, including areas 17, 18, and sometimes 19, was injected with tritiated leucine. Terminal labelling could be detected by autoradiography in the dorsocaudal part of the ipsilateral claustrum in all cases.
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  • 22
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    Experimental brain research 34 (1979), S. 241-261 
    ISSN: 1432-1106
    Keywords: Locomotion ; Central generator ; Cat ; Deafferentation ; Spinal cord
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A central network of neurones in the spinal cord has been shown to produce a rhythmic motor output similar to locomotion after suppression of all afferent inflow. The experiments were performed mainly in acute spinal cats (th. 12), which had received DOPA i.v. and the monoamine oxidase inhibitor Nialamide. In some preparations all dorsal roots supplying the spinal cord were transected, in others phasic afferent activity was suppressed by curarization. The activity was recorded as neurograms from nerve filaments or as electromyograms. It is concluded that: 1. alternating activity between flexors and extensors of foot, ankle, knee, and hip of one limb can still occur 2. the duration of the flexor discharges vary less with the cycle duration than the extensor discharges 3. different flexor muscles may retain individual patterns 4. the activity at different joints can be dissociated 5. there is at least one network for each limb 6. the coordination between the two hindlimbs can be alternating as in walking or be more closely spaced as in galloping 7. alternating activity in the ankle remains even when only segments L6, L7 and S1 are intact.
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  • 23
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    Pflügers Archiv 382 (1979), S. 51-55 
    ISSN: 1432-2013
    Keywords: Cerebellectomy ; Vestibuloocular reflex ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The effects of cerebellectomy on the semi-circular canal evoked responses recorded from individual vertical and oblique eye muscles were studied in cats anesthetized with Ketamine. The phase lag relative angular acceleration of the electromyographic response was consistantly smaller over the frequency range tested (0.02–1.0 Hz) in cerebellectomized than in intact animals. This finding indicates that the time constant of the central, neural integrator was shifted towards smaller values by the lesion. This was also suggested when the vertical eye movements generated by rotation about the pitch axis were recorded in the fully alert animal. In addition, the EOG data show that the phase of the VOR in the low frequency range was not altered following cerebellectomy suggesting that the macular influences were still present. When the EMG responses of the superior oblique (SO) and superior rectus (SR) muscles were studied in their presumed main mode, i.e. roll-canal and pitch-canal, respectively, no difference was noted in hemicerebellectomized animals when compared to intact control animals. However, when SO and SR were studied in pitch-canal and roll-canal rotation, respectively, dramatic changes in the response pattern were noted in lesioned animals.
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  • 24
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    Psychopharmacology 63 (1979), S. 151-153 
    ISSN: 1432-2072
    Keywords: Discriminative stimulus properties ; Psychomotor stimulants ; Cat ; d-Amphetamine ; Clozapine ; Cocaine ; Morphine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Cats were trained to choose between two levers of an operant chamber using interoceptive cues provided by d-amphetamine or saline as the discriminative stimuli. Following training, stimulus generalization was observed to additional doses of d-amphetamine and cocaine, but not to morphine. Clozapine blocked the generalization of the drug discrimination response to d-amphetamine, but had no effect on generalization to cocaine. These data indicate that discriminative stimulus properties of psychomotor stimulants, previously described in rats, are similar in cats.
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  • 25
    ISSN: 1432-0878
    Keywords: Thalamus ; Horseradish peroxidase ; Golgi-impregnation ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Afferent connections to the ventrobasal complex (VB) of the thalamus were studied by means of retrograde transport of horseradish peroxidase (HRP) and by the Golgi-method. After HRP-injection into the VB, peroxidase-positive cells were observed contralaterally in the dorsal column nuclei (DCN), in the trigeminal nuclei and in the lateral cervical nucleus (LCN), and ipsilaterally in the somatosensory I (SI) and II (SII) cortical areas. Labeled cells of different shape and size were compared with neurons impregnated by the Golgi-technique. On the basis of HRP-labeling it is concluded that cells projecting to the VB are different in size and shape even within one region and that they correspond to the relay or efferent neurons observed in the Golgimaterial.
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  • 26
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    Springer
    European archives of oto-rhino-laryngology and head & neck 222 (1979), S. 113-118 
    ISSN: 1434-4726
    Keywords: Brain-stem electric response (BSER) ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The early auditory evoked responses have been studied in bilaterally hearing cats, and in animals with hereditary unilateral anacusis. Cross-over stimulation of the hearing ear occurs at an interaural attenuation of 50-50 dB, and all six waves of the responsare present at supra-threshold stimulus levels.
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  • 27
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    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 112 (1979), S. 2012-2021 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Bicyclo[2.1.1]hexanes from Tricyclo[3.1.0.02,6]hexanesThe novel tricyclo[3.1.0.02,6]hexane derivatives 3 and 4, being fused with a fife- and a sixmembered ring respectively, are prepared from benzvalene in several steps. They and their lower homologues 1 and 2, having a three- and fourmembered ring respectively, add thiophenol under conditions of a radical reaction to form smoothly one cyclobutylphenyl thioether (16-19) in each case. Therefrom the parent hydrocarbons (5-8) which contain the bicyclo[2.1.1]hexane skeleton, are obtained by means of reduction with lithium in ethylamine.
    Notes: Ausgehend von Benzvalen werden in mehreren Stufen die neuen Tricyclo[3.1.0.02,6]hexan-Derivate 3 und 4 mit anelliertem Fünf- bzw. Sechsring dargestellt. Sie und ihre niedrigeren Homologen 1 und 2 mit Drei- bzw. Vierring nehmen unter Bedingungen einer Radikalreaktion Thiophenol auf, wobei glatt jeweils ein Cyclobutylphenylthioether (16-19) gebildet wird. Mit Lithium in Ethylamin sind aus 16-19 die tricyclischen Stammkohlenwasserstoffe mit dem Bicyclo[2.1.1 ]hexan-Gerüst (5-8) erhältlich.
    Additional Material: 2 Ill.
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  • 28
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    Berichte der deutschen chemischen Gesellschaft 112 (1979), S. 2022-2027 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The Influence of Fused Rings on the 13C Shieldings of Tricyclo[3.1.0.02,6]hexane and Bicyclo[2.1.1]hexane DerivativesThe 13C shieldings of the tricyclo[3.1.0.02,6]hexane derivatives 2-5 and of the bicyclo[2.1.1]-hexane derivatives 7-10 and 12-15 show a strong dependence on the size of the fused rings. Especially the γ-anti-effects, which cause downfield shifts, and the γ-syn-effects of these rings, which result in upfield shifts, are subject to unexpected variations.
    Notes: Die 13C-chemischen Verschiebungen der Tricyclo[3.1.0.02,6]hexan-Derivate 2-5 und der Bicyclo[2.1.1]hexan-Derivate 7-10 und 12-15 zeigen eine starke Abhängigkeit von der Größe der anellierten Ringe. Insbesondere die nach tieferem Feld gerichteten γ-anti-Effekte und die nach höherem Feld gerichteten γ-syn-Effekte dieser Ringe unterliegen unerwarteten Variationen.
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  • 29
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    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 112 (1979), S. 1902-1912 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Reactions with Indole Derivatives, XXXIX. A Stereoselective Synthesis of Eburnamonine, Eburnamine, and EburnamenineStudies on the five-membered lactams 1 and 2 disclose a stereoselective access to eburnamonin-19-one (22). This substance is easily transformed into eburnamonine (25), eburnamine (30), and eburnamenine.
    Notes: Das Studium der 5-Ring-Lactame 1 und 2 eröffnet einen stereoselektiven Zugang zum Eburnamonin-19-on (22). Diese Substanz läßt sich auf einfache Weise in die drei Alkaloide Eburnamonin (25), Eburnamin (30) und Ehurnamenin überführen.
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  • 30
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    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 112 (1979), S. 1916-1918 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ene Reactions with CyanothioformanilidesCyanothioformanilides 3 react with methylenecyclohexane (1) and β-pinene (2) in boiling toluene to yield the adducts 4 and 5, resp., according to the mechanistic scheme of an ene reaction.
    Additional Material: 3 Tab.
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  • 31
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    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 112 (1979) 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 32
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    Berichte der deutschen chemischen Gesellschaft 112 (1979), S. 1919-1922 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthese von neuen chiralen KohlenwasserstoffenUnsymmetrisches Anheften einer aliphatischen (CH2)n-Brücke an ein an sich achirales aromatisches System führt zu starren chiralen Kohlenwasserstoffen des Typs 2; die Enantiomeren 2 a konnten mit Hilfe von TAPA angereichert werden. Die Racemisierungskinetik wurde polarimetrisch bestimmt: ΔG≠20 = 93.6 kJ · mol-1.
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  • 33
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    Berichte der deutschen chemischen Gesellschaft 112 (1979), S. 1923-1925 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Pheromones, XXIV. Synthesis of the Sex Attractants (Z)-7-Dodecenyl Acetate and (Z)-7-Tetradecenyl Acetate(Z)-7-Dodecenyl acetate, the female sex pheromone of the Noctuid moth Trichoplusia ni, and (Z)-7-tetradecenyl acetate, the sex attractant of Amathes c-nigrum (Lepidoptera), are prepared by stereoselective Wittig olefination using the „silazide“ -technique.
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  • 34
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    Berichte der deutschen chemischen Gesellschaft 112 (1979), S. 1927-1933 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Dynamic NMR Studies of (Di-tert-butylamino)arsanes and -stibanesThe reaction of LiN[C(CH3)3]2 with AsX3 (X = F → Br). (CH3)3CAsCl2 and SbCl3 yields the di-tert-butylamino)arsanes 1a-c, 2 and dichloro(di-tert-butylamino)stibane (1d). LiN(CR3)-(SiR3), R=CH3and 1a-c form 3. The El — N torsional barriers of these compounds (measured by temperature dependent 1H-NMR spectroscopy) are compared with those of the (diisopropylamino)arsanes 4. and other related compounds. The influence of the N and El ligands with respect to the El — N torsional barrier is discussed. Thermolysis of 3c affords the di-tert-butylaminyl radical.
    Notes: Durch Umsetzung von LiN[C(CH3)3]2 mit AsX3 (X = F → Br), (CH3)3CAsCl2 und SbCl3 erhält man die (Di-tert-butylamino)arsane 1a-c und 2 sowie Dichlor(di-tert-butylamino)stiban reagieren mit LiN(CR3)(SiR3), R=CH3 zu 3 weiter. Die durch temperaturabhängige 1 H-NMR-Messungen ermittelten El- N-Rotationsbarrieren dieser Verbindungen werden hinsichtlich des Ligandeneinflusses am N- El - Atom mit den (Diisopropylamino)arsanen 4. und verwandten Molekülen verglichen. 3c. ergibt bei der Thermolyse das Di-tert-butylaminyl-Radikal.
    Additional Material: 1 Tab.
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  • 35
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    Berichte der deutschen chemischen Gesellschaft 112 (1979), S. 1934-1940 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Isocyanide Complexes, I. Isocyanophosphanes and -arsanes as Ligands of ComplexesThe reaction of K[CpMn(CO)2CN] (Cp = η-C5H5) with PR2Cl (R=C2H5, OC2H5, C6H5) and As(C6H5)2Cl yields the complexes CpMn(CO)2CNPR2 (3a - c) and CpMn(CO)2CNAsPh2 (3d) with C-coordinated isocyanophosphanes and -arsanes. In the reaction of CpMn(CO)2CNPPh2 with CpMn(CO)2 THF or of K[CpMn(CO)2CN] with CpMn(CO)2PPh2Cl a complex with an isocyanophosphane bridge, {CpMn(CO)2}2(CNPPh2) (4), is obtained. The IR, NMR, and mass spectra of the compounds 3a-d and 4 are discussed.
    Notes: Bei der Umsetzung von K[CpMn(CO)2CN] (Cp = η-C5H5) mit PR2Cl (R=C2H5, OC2H5, C6H5) und As(C6H5)2Cl entstehen die Komplexe CpMn(CO)2CNPR2 (3 a - c) und CpMn(CO)2CNAsPh2 (3d) mit C-gebundenen Isocyanphosphanen und -arsanen. Durch Reaktion von CpMn(CO)2CNPPh2 (3c) mit CpMn(CO)2 THF bzw. von K[CpMn(CO)2]CN mit CpMn(CO)2PPh2Cl erhält man den Komplex {CpMn(CO)2}2(CNPPh2) (4) mit einer Isocyanphosphan-Brücke. Die IR-, NMR- und Massenspektren der Verbindungen 3a-d und 4 werden diskutiert.
    Additional Material: 3 Tab.
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  • 36
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    Berichte der deutschen chemischen Gesellschaft 112 (1979), S. 1941-1947 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Barriers to Hindered Rotation Around the N-Glycosidic Bond, IV. 1-(βD-Ribofuranosyl) isocyanuric AcidsThe β-ribofuranosyl nucleosides 5a-c and 6b, c are synthesized. The temperature dependency of the 1H- and 13C-NMR spectra can only be interpreted as hindered rotation around the N-glycosidic bond2). The Gibbs activation energies (43-46 kJmol-1) are independent of acetylation of the OH groups of the furanose ring or restriction of its flexibility through formation of a 2′,3′-isopropylidene derivative, and are considerably lower than the corresponding data (about 69 kJmol-1) of the glucopyranosyl nucleosides 7b, c. The activation entropies are small. The results are interpreted.
    Notes: Es werden Synthesen der β-Ribofuranosylnucleoside 5a-c und 6b, c beschrieben. Die Temperaturabhängigkeiten der 1H-und 13C-NMR-Spektren lassen sich nur als Folge behinderter Rotation um die N-glycosidische Bindung deuten2) Die Gibbsschen Aktivierungsenergien (43-46 kJmol-1) sind unabhängig von einer Acetylierung der OH-Gruppen des Furanoseringes oder einer Einschränkung von dessen Flexibilität durch Bildung eines 2′,3′-Isopropylidenderivates und liegen erheblich tiefer als die entsprechenden Werte (um 69 kJmol-1) der Glucopyranosylnucleoside 7b, c. Die Aktivierungsentropien sind gering. Die Befunde werden gedeutet.
    Additional Material: 3 Tab.
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  • 37
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    Berichte der deutschen chemischen Gesellschaft 112 (1979), S. 1948-1955 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Syntheses of α-BromoisothiocyanatesSecondary isothiocyanates (1j-q) and primary isothiocyanates R—CH2 - NCS with an activating group R (1f, g) react with N-bromosuccinimide (NBS) to form α-bromoisothiocyanates 2 in high yields. The not activated primary isothiocyanate 1c slowly forms the stable α,α-dibromoisothiocyanate 10. In the presence of β-hydrogens some of the α-bromoisothiocyanates 2 eliminate HBr spontaneously, and secondary products may be formed. The α-bromination of isothiocyanates is a radical reaction following a Goldfinger mechanism.
    Notes: Sekundäre Isothiocyanate (1j-q) und primäre Isothiocyanate R-CH2 - NCS mit einer aktivierenden Gruppe R (1f, g) lassen sich mit N-Bromsuccinimid (NBS) in hohen Ausbeuten zu den α-Bromisothiocyanaten 2 bromieren. Das nicht aktivierte Isothiocyanat 1c reagiert langsam zum stabilen α,α-Dibromisothiocyanat 10. Bei Anwesenheit von β-Wasserstoffatomen spalten die α-Bromisothiocyanate 2 zum Teil spontan HBr ab, und es entstehen Folgeprodukte. Die α-Bromierung der Isothiocyanate erfolgt radikalisch nach einem Goldfinger-Mechanismus.
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  • 38
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    Berichte der deutschen chemischen Gesellschaft 112 (1979), S. 1956-1972 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Reactions of α-Bromoisothiocyanatesα-Bromoisothiocyanates 11.2) with a hydrogen in β-position eliminate HBr to form vinyl isothiocyanates (products 2, 3, 5). Water hydrolyzes 1 to carbonyl compounds (7a). Hard nucleophiles attack 1 at the α-C-atom with substitution of bromine (products 8-12), but soft nucleophiles add to the C-atom of the isothiocyanato group (products 14, 19). Compounds 1 react with bifunctional nucleophiles to heterocycles (e. g. products 16, 21). The chemical properties of the classes of compounds, part of which are new, e. g. the geminal diisothiocyanates 12, are examined. The alkylidene thiourea 14f shows hindered rotation around the amide-CS—N bond (ΔG≠394 = 82.8 kJmol-1) and around the C=N double bond (ΔG≠244 = 52.9 kJmol-1).
    Notes: α-Bromisothiocyanate 1 mit einem β-Wasserstoff spalten HBr zu Vinylisothiocyanaten ab (Produkte 2, 3, 5). Wasser hydrolysiert 1 zu Carbonylverbindungen (7a). Harte Nucleophile greifen 1 am α-C-Atom unter Substitution des Broms an (Produkte 8-12), weiche Nucleophile lagern sich dagegen an das C-Atom der Isothiocyanatgruppe an (Produkte 14, 19). Verbindungen 1 reagieren mit bifunktionellen Nucleophilen zu Heterocyclen (z. B. Produkte 16, 21). Die chemischen Eigenschaften der z. T. neuen Verbindungsklassen, z. B. der geminalen Diisothiocyanate 12, werden untersucht. Der Alkylidenthioharnstoff 14f zeigt behinderte Rotation um die Amid Cs—N-Bindung (ΔG≠394 = 82.8 kJmol-1) und um die C=N-Doppelbindung (ΔG≠244 = 52.9 kJmol-1).
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  • 39
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    Berichte der deutschen chemischen Gesellschaft 112 (1979), S. 1973-1980 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The Crystal Structure and the Fluxional Behaviour in Solution of (η3-Allyl)dicarbonyl(triphenyl-phosphane)cobalt[Co(η3-C3H5)(CO)2PPh3] (1) crystallizes in the triclinic space group P1 with two molecules per unit cell. The crystal structure was solved and refined with X-ray diffraction data (R = 0.031, 2046 observed reflections). The cobalt atom has a distorted square pyramidal coordination with the formally bidentate η3-allyl ligand, the phosphane, and one carbonyl in the basal positions. According to the NMR spectra at temperatures down to 135 K, in solution there exists a fluxional equilibrium with the η3-allyl ligand oscillating between two enantiomeric positions.
    Notes: [Co(η3-C3H5)(CO)2PPh3] (1) kristallisiert triklin in der Raumgruppe P1 mit zwei Molekülen pro Elementarzelle. Die Kristallstruktur wurde mit Röntgenbeugungsdaten ermittelt und verfeinert (R = 0.031, 2046 beobachtete Reflexe). Das Cobaltatom ist verzerrt quadratisch-pyramidal koordiniert, mit dem formal zweizähnigen η3-Allylliganden, dem Phosphan und einem Carbonylliganden in der Pyramidenbasis. Nach den NMR-Spektren bei Temperaturen hinab bis 135 K liegt in Lösung ein dynamisches Gleichgewicht vor, bei dem die η3-Allylgruppe zwischen zwei enantiomeren Positionen fluktuiert.
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  • 40
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    Berichte der deutschen chemischen Gesellschaft 112 (1979), S. 1981-1990 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Hydrazidines, III. Synthesis of 1,2,4,5-Tetrazino[3,2-a]isoindolesReaction of acetohydrazide hydrazone hydrochloride (1) with phthalaldehydic acid (5) yields 3-methyl-1,10b-dihydro-1,2,4,5-tetrazino[3,2-a]isoindol-6(4H)-one (8), which affords 1,2,4,5-tetrazino[3,2-a]isoindol-6(4H)-one (9a) by mild oxidation. 9a is also obtained by the reaction of 1 with the phthalic acid derivatives 6a, 7a, and 7b. Starting with 9a, the 1,2,4,5-tetrazino[3,2-a]isoindoles 12-15 are synthesized. Interaction of 1 and 3-nitrophthalic anhydride (6b) yields two isomeric nitro-1,2,4,5-tetrazino[3,2-a]isoindol-6(4H)-ones (9b,c). Oxidation of 9a or b with KMnO4 in methanol affords the 1,2,4,5-tetrazino 17a, b. Mild Oxidation of 9a with KMnO4 in water/trichloromethane yields a dimer (20), which dissociates in nitromethane into the radical 19.
    Notes: Durch Reaktion von Acetohydrazid-hydrazon-hydrochlorid (1) mit Phthaladehydsäure (5) wird 3-Methyl-1, 10b-dihydro-1,2,4,5-tetrazino[3,2-a]isoindol-6(4H)-on (8) erhalten das durch milde Oxidation in 3-Methyl-1,2,4,5-tetrazino[3,2-a]isoindol-6(4H)-on (9a) übergeführt wird. 9a entsteht auch aus 1 und den Phthalsäurederivaten 6a, 7a und 7b. Ausgehend von 9a werden die 1,2,4,5-Tetrazino[3,2-a]isoindole 12-15 synthetisiert. Aus 1 und 3-Nitrophthalsäureanhydrid (6b) werden zwei isomere Nitro-1,2,4,5-tetrazino[3,2-a]isoindol-6(4H)-one (9b, c) erhalten. Oxidation von 9a oder b mit KMnO 4 in Methanol ergibt die 1,2,4,5-Tetrazine 17a, b. Vorsichtige Oxidation von 9a mit KmnO4 in Wasser/Chloroform ergibt ein Dimeres (20), das in Nitromethan in das Radikal 19 dissoziiert.
    Additional Material: 2 Ill.
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    Berichte der deutschen chemischen Gesellschaft 112 (1979), S. 1991-1998 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Stereochemistry of the Metal-Metal Bond. Structural Comparison of the Complexes Cr2(CO)8(AsMe2)2, CrFe(CO)7(AsMe2)2, and Fe2(CO)6(AsMe2)2The molecular structures of the new complexes CFer2(CO)8(AsMe2)2 (1) and CrFe(CO)7(AsMe2)2 (2) were determined crystallographically, that of Fe2(CO)6(AsMe2)2 (3) was redetermined. In all three compounds the metal-metal bond lengths are determined by the goemetrical requirements of the ligands. The fact that the M2As2 framework is planar in 1 and strongly folded in 2 and 3 can also be explained by the steric demands of the ligands. Aspects of the fluxionality of these complexes are discussed.
    Notes: Die Molekülstrukturen der neuen Komplexe Cr2(CO)8(AsMe2)2 (1) und CrFe(CO)7(AsMe2)2 (2) wurden kristallographisch ermittelt, die von Fe2(CO)6(AsMe2)2 (3) wurde neu bestimmt. In allen drei Verbindungen sind die Metall-Metall-Bindungslängen durch die geometrischen Ansprüche der Liganden festgelegt. Auch die Tatsache, daß das M2As2-Gerüst in 1 eben und in 2 und 3 jeweils stark gefaltet ist, läßt sich auf den Raumbedarf der Liganden zurückführen. Aspekte der Fluktuation dieser Komplexe werden diskutiert.
    Additional Material: 2 Ill.
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  • 42
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    Berichte der deutschen chemischen Gesellschaft 112 (1979), S. 1999-2011 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Investigations on Metabolites of Microorganisms, XX. The Structures of the Flexirubin-type Pigments from Cytophaga johnsonae CyjlCytophaga johnsonae Cy jl produces more than 25 different flexirubin-type pigments (2 a-h, 3 a-h, 4 a-h, 5) besides lower concentrations of carotenoids. These pigments could be separated using HPLC. Their structures have been elucidated. 5 is the first known member in this class of bacterial pigments containing two chlorine atoms.
    Notes: Das Gleitende Bakterium Cytophaga johnsonae Cy jl produziert neben wenig Carotinoiden mehr als 25 verschiedene Pigmente vom Flexirubin-Typ (2a-h, 3a-h, 4a-h, 5), deren Trennung u.a. durch Hochdruckflüssigchromatographie gelang. Über die Konstitutionen dieser Pigmente wird berichtet. Mit 5 wurde erstmals in dieser Verbindungsklasse ein dichlorhaltiges Pigment aufgefunden.
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  • 43
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    International Journal of Quantum Chemistry 15 (1979) 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 44
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    International Journal of Quantum Chemistry 15 (1979), S. 121-129 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The molecular electrostatic potentials computed by the overlap-multipole-expansion procedure (OMTP) are compared to exact electrostatic potentials computed with the same Gaussian basis set, for different molecular species. It is shown that at distances of the molecule larger than 2.2 Å, the OMTP values compared to those of the exact ones are within an error of 0.5 kcal/mol. This error decreases with increasing distance. For distances below this limit the OMTP potentials may be used as a first indication of the trends of the molecule, provided the values to compare are not too close.
    Additional Material: 4 Ill.
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  • 45
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    International Journal of Quantum Chemistry 15 (1979), S. 109-120 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The random-walk method of solving the Schrödinger equation is applied to the 1B1g and 1B2g states of the H4 square with side length 2.4 a.u. The results provide an independent check of the accuracy of prior variational calculations for these states. With node structures for the 1B1g state taken from a variational calculation with a single-zeta basis set and taken in the simplest form meeting symmetry requirements, the calculated energies are lower than the expectation value of the energy for the single-zeta basis set but not as low as the expectation value for an optimized-exponent double-zeta basis set with polarization terms. Comparisons of results give no suggestion of a barrier height lower than ∼120 kcal/mol for passage through the square configuration in the exchange reaction H2 + D2 → 2HD. For the 1B2g state with node structure in the simplest form meeting symmetry requirements the calculated energy is ∼65 kcal/mol lower than the expectation value of the energy for variational calculations with a double-zeta basis set.
    Additional Material: 6 Ill.
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  • 46
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    International Journal of Quantum Chemistry 15 (1979), S. 135-145 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Two distinct approaches to the calculation of first-order properties with a limited CI wave function are discussed. One is based on the Hellmann-Feynman theorem and the other on the direct evaluation of the total energy derivative at zero perturbation. Corrections to the Hellmann-Feynman expectation value are given for the CI wave function consisting of a single determinant reference state and all single and double replacements of this. These corrections are the extended Brillouin matrix elements and involve interactions between the zeroth-order wave function and triply substituted configurations. The usefulness of these matrix elements for the generation of MC SCF orbitals and for the calculation of cluster corrections to the wave function is briefly discussed. The formulas for the Brillouin matrix elements expressed in terms of one- and two-electron integrals have been automatically generated using the syntax of the algebraic program SCHOONSCHIP.
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  • 47
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    International Journal of Quantum Chemistry 15 (1979) 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 48
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    International Journal of Quantum Chemistry 15 (1979), S. 207-242 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We argue that the goal of developing a satisfactory general formalism for the justification of effective π-electron Hamiltonians, as well as for ab initio calculation of their parameters (α, β, and γ), has now been achieved. The need for a fully linked many-body formalism is emphasized; this feature requires a Rayleigh-Schrödinger (RS) type of degenerate perturbation theory. A number of apparently different degenerate RS perturbation formalisms are reviewed. Most of these formalisms are actually identical term-by-term, when their RS expansions are worked out explicitly; the formal relations that prove their complete equivalence are presented and discussed. One of these formalisms, a version developed by the author for related open-shell problems in nuclear physics, is shown to be most convenient for many-body applications. This is owing to the relatively simple and transparent nature of its general algebraic structure, which facilitates partial summation to infinite order. A simple and concise derivation is presented for the algebraic features of this preferred formalism, and its many-body (linked cluster) aspects are briefly discussed. The recent development of a nonperturbative (coupled-cluster) analog of this formalism is also described. Some practical issues are examined, including the choice of orbital basis. Illustrative numerical results are presented, based on the calculations of Iwata and Freed. Several remaining problems are described; these are both qualitative and quantitative in nature, and their resolution will require some detailed calculations.
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  • 49
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    International Journal of Quantum Chemistry 15 (1979), S. 359-359 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 50
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    International Journal of Quantum Chemistry 15 (1979), S. 389-401 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: It is found that ordinary STOs fall off too fast in the atomic region in many cases. A new type of basis set, which is more adaptable to the rather different requirements of the various atomic orbitals in an atom, is developed. The suggested functional form χ(r) = Nrn-1 exp{-α[(βr + 1)1/2 - 1]} contains the STOs as a limiting case. Calculations on a series of atoms from H to Zn show that the new basis gives better results than STOs for equal basis set size. The necessary integrals do not present any problem to evaluate.
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  • 51
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    International Journal of Quantum Chemistry 15 (1979), S. 403-410 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The valence spectrum of CoO has been calculated using the CoO610- cluster, stabilized by an electrostatic field, as a model of bulk CoO. The wave functions were generated using basis sets of better than double-zeta quality. SCF wave functions were obtained for the ground state and for the first ionized state of the cluster. Limited CI calculations were performed using these orbital sets. The lowest states of the ion correspond to the main lines in the spectrum, while higher states can give rise to high-energy satellites to the main lines. The relative intensities of these satellites were estimated in the case of high-energy incident photons.
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  • 52
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    International Journal of Quantum Chemistry 15 (1979), S. 445-445 
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    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 53
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    International Journal of Quantum Chemistry 15 (1979), S. 411-421 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Pseudospectra from Gaussian basis set calculations within a frozen-core approximation have been used in a moment analysis to obtain Tchebychev profiles for the photoabsorption process in the valence shell of Ne. The profiles show good agreement with cross sections obtained in equivalent calculations using numerical atomic wave functions and continuum orbitals, particularly when the dipole-velocity form is employed. Variation of the basis sets shows that it is possible to obtain meaningful photoabsorption profiles using 13-15 virtual orbitals to describe the outgoing electron.
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  • 54
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    International Journal of Quantum Chemistry 15 (1979), S. 481-489 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The paper reports the study of a possible mechanism of Ca+2 activation of prostaglandin PGF2α on the basis of molecular-orbital and conformation-energy calculations. The electronic charges on various atoms of the molecule have been evaluated from the available crystallographic data by the extended Hückel theory (EHT). Conformation energies were calculated for intrinsic torsional rotations around the C11—C12, C7—C8, and C14—C15 bonds. The minimum energy conformation was found to differ from the crystallographic conformation by 9.3 kcal/mol. Some additional local energy minima are also reported within this range. The calculation of the long-range interchain interaction energy between the α and ω chains shows variation with conformation. The binding site for the Ca+2 ion has been estimated on the basis of the molecular electrostatic potentials. Such a binding site was found near the carboxyl group, which agrees with the current chemical thinking. Changes in the electronic charge distribution due to Ca+2 complexation were studied by EHT method using the supramolecular approach. Calcium complexation decreases the conformation energy by 2-3 kcal/mol and has a small effect on the interchain interaction energy.
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  • 55
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    International Journal of Quantum Chemistry 15 (1979), S. 491-497 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Several analogs of valinomycin have been simulated. These are analogs obtained by changing the configuration of the amino acid and hydroxy acid residues one at a time. Nonbonded interactions have been calculated for three conformations of each analog. The electrostatic and polarization contributions to the energy are conformation selective, whereas the Pauli repulsion is the only component which is isomer selective. For the ring chirality considered here the analog of valinomycin having all the three L-valyl residues replaced by D-valyl residues is predicted to be frozen in a “top open” conformation.
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  • 56
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    International Journal of Quantum Chemistry 15 (1979), S. 499-510 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The ab initio SCF LCAO-MO method is used to compute the main electronic properties of a purine nucleoside, adenosine, in two specific conformational arrangements (3′-endo conformation of the ribose, gt orientation of the extracyclic CH2OH group, anti orientation of the base with respect to the sugar and 3′-endo conformation of the ribose, gg orientation of the extra-cyclic CH2OH group, syn orientation of the base with respect to the sugar). The results are compared with those performed for the isolated component fragments, adenine and 3′-endo riboses.
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  • 57
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    International Journal of Quantum Chemistry 15 (1979) 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 58
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    International Journal of Quantum Chemistry 15 (1979), S. 547-557 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The cyanide-isocyanide isomerization has been studied with ab initio calculations in an STO-3G basis as applied to NCNCO, NCCNO, NCOCN, and NCONC, and the corresponding isocyanides. Geometry optimization has been performed on these cyanides, their isocyanides, and their hypothetical transition states. The energies of isomerization were calculated to be 42.2, 29.8, 44.6, and 41.4 kcal/mol, respectively, while the energy barriers were found as 84.3, 67.5, 107.9, and 106.8 kcal/mol. Overlap populations and atomic charges were employed to provide simple correlations of the results.
    Additional Material: 4 Ill.
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  • 59
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    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Configuration-interaction calculations, with an extended basis, are carried out on the ground and lower excited states of O2 and O2+ at and near the equilibrium internuclear distance (R = 2.3 a.u.) of the ground state of O2. Particular attention has been paid to the two lowest 3Σu- states, and the mixing of the valence and Rydberg characters in these states are studied. The lowest 3Σu- state is a Rydberg-type state for R 〈 2.3 a.u., but becomes valence-type for R ≳ 2.3 a.u. The second 3Σu- state, which is 1.6 eV above the lowest 3Σu- at R = 2.3 a.u., changes its character from Rydberg to valence, valence to Rydberg, and then to valence again when R increases from 1.9 to 3.1 a.u. Satisfactory agreement between the calculated and experimental vertical excitation energies is obtained.
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  • 60
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    International Journal of Quantum Chemistry 15 (1979), S. 559-566 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new form of pseudopotential for applicaiton in ab initio molecular calculations is described. A method for determining pseudopotential parameters is suggested and pseudopotential parameters of double-zeta quality are presented for the first row atoms of the periodic table. The pseudopotential is especially well suited for incorporation into the floating-spherical-Gaussian-orbital (FSGO) method, though it is not restricted to any particular method. Applications of the resulting pseudo-FSGO method to BeH2, BH3, CH4, and C2H6 are presented.
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  • 61
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    International Journal of Quantum Chemistry 15 (1979), S. 567-578 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Pseudopotential theory is introduced into the ab initio FSGO molecular fragment method. A theoretical background for the pseudopotential fragment description and a method for large molecule formation is presented. Core-valence electron separation is achieved at both levels of the calculations with the resulting simplification of the molecular calculations. Using pseudopotentials of double-zeta quality a detailed description of pseudopotential molecular fragments CH4 (tetrahedral) and CH3 (planar) is presented. Applications of the pseudo-FSGO molecular fragment method to hydrocaroons are discussed. The results are compared to those of the original FSGO method and experiment.
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  • 62
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    International Journal of Quantum Chemistry 15 (1979), S. 579-588 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A procedure is outlined for a programmable spin-free configuration-interaction (CI) study in molecules using single-parameter alternant molecular orbitals for generating various configurations. The configurations were chosen to form bases for the irreducible representation {2N/2-2, 12S} of the general linear group GL(n). Using a transformation to biorthogonal space the CI matrix elements of a spin-free Hamiltonian were generated. The procedure has been used to obtain the π-electron energies for the 3,1Ag and 3,1Bu states of cis- and trans-butadiene.
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  • 63
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    International Journal of Quantum Chemistry 15 (1979), S. 713-715 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The Longuet-Higgins group is used to obtain an alternative formulation of a criterion for optical activity of nonrigid molecules recently given by Frei and Günthard.
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  • 64
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    International Journal of Quantum Chemistry 16 (1979), S. 5-17 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The properties of exciton and soliton excitations in one-dimensional molecular systems and in α-helical protein molecules are investigated. It is shown that collective excitations - solitons, corresponding to a combination of vibrational excitations in peptide groups and a local deformation of molecules - are possible in α-helical protein molecules. These excitations move along the molecule without energy losses and are perfect energy carriers. A qualitative description of the shortening in the length of muscular fibers is given using the concept of solitons occurring under the hydrolysis of ATP molecules at the ends of thick fibers contained in the sarcomeres of muscular fibers.
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  • 65
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    International Journal of Quantum Chemistry 16 (1979), S. 31-42 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new electron structural mechanism is proposed for interpretations in molecular biology, in addition to the already existing theories of Szent-Györgyi (semiconductivity) and Fröhlich (long-range coherence). The hypothetical “intermediate-” or “zigzag states” (ZZS) of solids are investigated by the recursion (transfer matrix) method. The physical reality of the ZZS is discussed up to an SCF DODS-type theory and the necessity of additional less approximate investigations is emphasized. The possible role of ZZS in the explanation of: (i) translation in protein synthesis, (ii) energy and charge transfer processes, as well as (iii) initiation of protein formation is outlined.
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  • 66
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    International Journal of Quantum Chemistry 16 (1979), S. 19-29 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Preferred conformations of phospholipids have been predicted through quantum-chemical techniques and classical potential functions. An essential condition for a conformation to exist in a biomembrane is that it should be possible for it to organize in the form of a bilayer. Taking into consideration the conformational flexibility of the polar head group, organization at the lipid-water interface has been considered. The biological implications of such an organization in terms of formation of “hydrophobic channels” is discussed. Quantum-mechanical investigations on the transport phenomenon have shown that the “selectivity” of biological membranes is connected with the “organization.” Calculations of the quantum-mechanical transmission coefficients for different model potential profiles indicate that minor differences in the height of potential barriers in certain regions can lead to significant changes in transmission coefficients. The “directional selectivity” of substrates (differences in transmission coefficients for flow in and out of the cell) can be explained on the basis of differences in membrane organization. These results have some important consequences in the evolutionary process in biological membranes.
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  • 67
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    International Journal of Quantum Chemistry 16 (1979), S. 43-50 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In the myosin-auramine O system 10 or 11 binding sites of auramine O on the rod-like part of myosin were discovered. The myosin fluorescence decreases with an increase in auramine O concentration. This is evidence of the excitation energy transfer from tryptophanyls situated near the binding sites to auramine O. The effective distance of energy transfer is 35 Å. It is suggested that the light meromyosin has binding sites with periodicities of 77-86 Å. Every binding site has a negative charge and hydrophobic locus.
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  • 68
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    International Journal of Quantum Chemistry 16 (1979), S. 51-56 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The transition from quantum chemistry to quantum biology is discussed, and the contributions that quantum biology can make to the study of biological structure and process are outlined. The need for extensions to the theory to deal with larger systems, to include solvent effects and to account for specificity, are emphasized.
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  • 69
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    International Journal of Quantum Chemistry 16 (1979), S. 57-64 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Pseudopotential theory is introduced into the ab initio FSGO molecular fragment method. Pseudopotential molecular fragments using pseudopotentials of double-zeta quality are characterized, and a method of their assembly into larger molecules is presented. Core-valence electron separation is achieved at both levels of the molecular calculations. Heteroatom incorporation into the method is also considered. Applications of the pseudo-FSGO molecular fragment method to hydrocarbons and simple molecular systems containing heteroatoms are discussed. Results are compared to those of the original FSGO method and experiment.
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  • 70
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    International Journal of Quantum Chemistry 16 (1979), S. 65-70 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Pair energies contributing to the correlation energies of the outer-shell electrons (n = 3) as well as for the 1s2 and 2s2 pairs are computed for the Zn2+ closed-shell ion by means of the variational-perturbation method starting with the sum of one-electron Hartree-Fock operators as the zeroth-order Hamiltonian. The results allow an understanding of the electron correlation for pairs of electrons of the p and d type. For 3p3d pairs it has been found that the correlation energy for the singlet pair of 1D symmetry is lower than for the triplet pair 3D. The 3l-3l′ correlation energies are compared with the MBPT results of Kelly and Ron for Fe. The total correlation energy of the outer shell is -1.032 a. u.
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  • 71
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    International Journal of Quantum Chemistry 16 (1979), S. 71-77 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The intermolecular electronic correlation contributions to the Coulomb component of the nucleic acid base interaction energy are estimated. The Coulomb energy is evaluated with the use of atomic monopoles, which are determined from the π-electronic densities calculated by the SCF method and by employing partially or completely optimized APSG wave functions. When the correlation is thus taken into account, a systematic decrease in atomic charges occurs; this effect is considerable only if an optimized orbital set is used. As a result, the Coulomb interaction energy due to the π-electronic atoms decreases from -1.13 to -0.85 kcal/mol for the AT pair and from -7.15 to -4.61 kcal/mol for the GC pair.
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  • 72
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    International Journal of Quantum Chemistry 16 (1979), S. 79-86 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A method is described for processing the enthalpy, entropy, and Gibbs free energy terms of formation of the individual isomers of n-particle clusters obtained by means of quantum-chemical calculations, to enable a comparison of these partial theoretical characteristics with the overall experimental ones. The general scheme of weighting treatment is illustrated by examples based on recent quantum-chemical results of studies of isomeric forms of (NO)2, (H2O)5 and (D2O)5, and CH3OH · 3H2O and CH3OH · 6H2O clusters.
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  • 73
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    International Journal of Quantum Chemistry 16 (1979), S. 87-110 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The electronic structure of a series of 25 chlorinated dibenzo-p-dioxins and dibenzofurans has been characterized by means of the ab initio molecular fragment technique. This information has been employed to investigate some of the factors affecting the affinity of the molecules for the hepatic cytosol binding species described by Poland, Glover, and Kende. A quantitative structure-activity relationship involving electronic and steric parameters could be established from the data. It appears that the toxins act as electron acceptors in a charge-transfer complex with the receptor.
    Additional Material: 5 Ill.
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  • 74
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    International Journal of Quantum Chemistry 16 (1979), S. 111-117 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The circular dichroism of molecules, which are large compared to the wavelength of light, is considered. Explicit expressions are obtained for the circular dichroism and absorption of an exciton dimer and of a free particle on a helix. The dimensions are described for which the dipole approximation for the optical properties fails.
    Additional Material: 1 Ill.
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  • 75
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    International Journal of Quantum Chemistry 16 (1979), S. 133-152 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The analysis of modern physical mechanisms of electron transfer in proteins is given. The tunnel electron transfer and donor-acceptor electron transfer through conducting states of a protein chain are discussed in detail. The expressions for the values of the electron resonance interaction and the formulas for probabilities of electron transfer between vibronic levels of donor and acceptor states in the presence of “transverse” and “longitudinal” relaxation are given.
    Additional Material: 6 Ill.
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  • 76
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    International Journal of Quantum Chemistry 16 (1979), S. 119-132 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The expressions for the polymer absorption band hypochromism and oscillator strength are studied in frames of the first-order perturbation theory. The physically justified approximations for a polymer hypochromism calculation are indicated. The uniform interpretation of the effect origin is given independently on the approximation used. In frames of the perturbation theory the DNA hypochromism formula is obtained, from which the known experimental dependences of hypochromism on chain length and polymer helicity degree follows directly. The analytic expression of the DNA hypochromism dependence on AT pairs content is obtained. It is established that in most cases for natural DNA the nucleotide sequence does not influence in practice the value of the hypochromic effect.
    Additional Material: 1 Ill.
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  • 77
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    International Journal of Quantum Chemistry 16 (1979), S. 153-157 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The intramolecular interaction energy of the regular double-helical polynucleotide as a function of variables that determine the mutual position of base pairs and sugar pucker was calculated using atom-atom potentials. The calculations showed the existence of two valley-like regions with minimal values on the energetic surface. One of them corresponds to the A family of nucleic acids, the other to the B family. The points that correspond to the models constructed by means of x-ray data are placed in a conformational space near the lines that describe the position of the bottom of the valleys.
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  • 78
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    International Journal of Quantum Chemistry 16 (1979) 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 79
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    International Journal of Quantum Chemistry 16 (1979), S. 847-855 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The investigation of the factors determining the formation and stability of the higher biopolymers structures is one of the most important trends of the development of molecular biophysics. A feature common to most macromolecular systems under physiological conditions is that they function in an aqueous environment. Thus, it is natural to assume that the peculiarities of biological macromolecules structures and their functional activity as well are closely related to the specific properties of such a unique solvent as water. The investigations of the conformational changes of biopolymer, induced by dehydration of the macromolecule, give information about the nature of the forces stabilizing its structure. The dehydration of the macromolecule in solution can be attained by addition of a nonaqueous cosolvent. Generally low-molecular-weight aliphatic alcohols, amides, and amines are used as a nonaqueous component. At present a vast number of experimental and theoretical data concerning the properties of water and aqueous systems are available. The specificity of water as a solvent arises primarily from the spatial hydrogen-bonded structure. The addition of a nonaqueous component exerts changes in this structure, which evolve to the singularities of the physical characteristics of water-nonelectrolyte mixtures. It is generally assumed that nonelectrolytes may be divided, according to their effect on the spatial water structure, largely into two basic classes: (1) the structure makers, i.e., the compounds of aliphatic alcohols type; (2) the structure breakers, i.e., the compounds of urea type. The agents belonging to the first class show a stabilizing effect in the range of low nonelectrolyte content. At a certain critical concentration, Ccrit, characteristic of each substance, the nonaqueous solute molecules leave the cavities of the spatial water structure which leads to a disruption of the latter. The agents belonging to the second class exert a structure-breaking effect even in the range of extremely low concentrations, which arises from their high competitive ability for hydrogen bonding.
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  • 80
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    International Journal of Quantum Chemistry 16 (1979), S. 877-882 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The physical aspects of the primary charge separation processes in bacterial photosynthesis are discussed. The donor-acceptor model of electron transfer due to participation of protein current states is used. The kinetics of photosynthetic reaction center (PRC) processes is investigated and the PRC energetic scheme is constructed using the nonequilibrium density matrix method. It is shown that with allowance for the effect of vibrational sublevels of states participating in transitions the theory describes well experimental data.
    Additional Material: 3 Ill.
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  • 81
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This paper analyzes the low-temperature magnetic circular dichroism of NO-Fe(II)hemoproteins in detail. We include the Jahn-Teller effect in our consideration of the low-temperature MCD results.
    Additional Material: 3 Ill.
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  • 82
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    International Journal of Quantum Chemistry 16 (1979), S. 891-895 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The unrestricted HF method in the INDO approximation with optimized geometry was used to describe the electronic structure of the hetero-ring of verdazyl and the derivatives of the latter. The results obtained are in good agreement with the experimental EPR spectra of triphenylverdazyl radical and its dipole moment. These data may be a basis for understanding and predicting the chemical properties and reactivity of verdazyl and its derivatives.
    Additional Material: 1 Ill.
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  • 83
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    International Journal of Quantum Chemistry 16 (1979) 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 84
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    International Journal of Quantum Chemistry 15 (1979), S. 83-95 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A screened potential model (SPM) is formulated with Slater-type functions to reproduce the density of the electron shells. The orbital exponent for the valence shell is optimized to calibrate the SPM against experimental valence and Rydberg s and p energy levels for the alkali metals (Li, Na, and K) rare gases (He, Ne, Ar, and Kr), second-row atoms, and Cu, Zn, Mg, S, and Ga. The resulting one-electron wave functions are used to calculate the dipole and velocity forms of the oscillator strengths and 〈1/r3〉 for spin-orbit coupling. The excellent agreement with the averaged experimental results suggests that the SPM atomic orbitals are a good starting point for the evaluation of one-electron properties.
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  • 85
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    International Journal of Quantum Chemistry 15 (1979), S. 97-107 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The validity of two models used in comparisons of the UHF and PHF methods in hyperfine structure calculations is investigated for the lowest 2P state of Li. An improved model for the angular splitting of the core orbitals is proposed and shown to give an accurate description of both the UHF and the PHF wave functions.
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  • 86
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    International Journal of Quantum Chemistry 15 (1979), S. 131-131 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 87
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    International Journal of Quantum Chemistry 15 (1979), S. 261-270 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A number of Gaussian basis sets for carbon and silicon have been examined in terms of the one-electron properties of methane and silane. The convergence of the properties to their limiting values is not monotonic but, in general, a representation that involves five Gaussian functions per occupied atomic orbital on the heavy atom is sufficient to closely approach the limits. A relationship between the sizes and partitioned electronic energies is shown to hold to a good approximation for the Boys spatially localized molecular orbitals employed in this study.
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  • 88
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    International Journal of Quantum Chemistry 15 (1979), S. 281-291 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A simple model for surface reconstruction is developed utilizing the next-nearest-neighbor approximation within the framework of molecular-orbital theory. Exact energy expressions for this model and various special cases are derived, and they are illustrated by numerical results. The influence of a very weak surface deformation on the energy spectrum of surface states is also discussed.
    Additional Material: 4 Ill.
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  • 89
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    International Journal of Quantum Chemistry 15 (1979), S. 293-309 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Löwdin's correlation potential formalism has been used to define a modified bielectronic potential, allowing one to calculate the exact electronic energy, given the Hartree-Fock wave function. This modified potential is in principle peculiar to each electronic system, and is defined by a correlation factor depending on the interelectronic distance r2. The explicit calculation of the correlation factor has been performed for some two-electron atoms, in the 11S and 23S states, and for the beryllium atom. Examination of the results so obtained leads us to conclude in favor of the nonexistence of a universal modified bielectronic potential.
    Additional Material: 9 Ill.
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  • 90
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    International Journal of Quantum Chemistry 15 (1979), S. 271-280 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This paper offers a unified presentation of the main ring conformers of the diol expoxides, triol carbonium ions, and tetrols related to the “bay-region” benzo ring of carcinogenic metabolites of PAH and brings forward quantitative information through ab initio SCF computations about their relative energies. It substantiates and evaluates the energy of the syn epoxide-OH4 hydrogen bond and, on the contrary, refutes the significance of an O⃛H—O or an O-⃛H—O bond in the triol carbonium ions. It provides an explanation for the similar rates of acid-catalyzed hydrolysis of the syn and anti diol expoxides. It evaluates the stabilization of the triol carbonium ions due to the presence of a neighboring double bond and accounts for the spontaneous opening of protonated epoxides. Finally it accounts for cis hydrolysis of the syn diol epoxide and trans hydrolysis of the anit diol epoxide under acid conditions.
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  • 91
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    International Journal of Quantum Chemistry 15 (1979), S. 333-341 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A dynamical model describing DNA as superconductant is proposed. The status of superconductivity is described as being represented by a radiation-induced harmonic oscillation of a parcel of π electrons between the reference level and critical temperatures. A set of field equations is used to describe the information exchange process mediated by a coherent wave phenomenon.
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  • 92
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    International Journal of Quantum Chemistry 15 (1979), S. 379-387 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new theoretical approach to the cooperativity of an enzyme has been proposed. When we applied the present theory to the allosteric effect of hemoglobin, we obtained a so-called Koshland-Nemethy-Filmer formula. Our theory suggested that the sigmoid curve becomes sharper when the affinity of the first oxygen molecule of the hemoglobin is smaller.
    Additional Material: 4 Ill.
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  • 93
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The atomic dipole approximation has been employed to calculate the energies of electrostatic interaction between adenine and various pyrimidine derivatives. Minima of the interaction energy for various planar configurations were determined. Inclusion of the “monopole-dipole” and “dipole-dipole” terms in the multipole expansion improves considerably the agreement with experimental data. The effect of sulfur substitution has been investigated in detail. Formation of N—H…S hydrogen bonds is less favorable than of N—H…O bonds, due largely to the lower atomic dipole of the sulfur atom resulting from the shift of the π-electron charge toward the neighboring carbon. The results are relevant to the interactions of thiouracils in nucleic acids.
    Additional Material: 2 Ill.
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  • 94
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The physical interpretation of intermolecular interactions is usually based on the well-known multipole expansion of the inverse of the interparticle distance. The interaction energy is then interpreted as a sum of terms arising from the interaction of various multipole moments of both systems. It is supposed that the interaction energy calculated via the truncated multipole expansion generally depends on the choice of local coordinate systems through the coordinate dependence of the multipole moments. In this paper we prove that each term of the multipole expansion given in the form ∑k = 1 Ck/Rk is invariant with respect to identical translations and arbitrary rotations of the local coordinate systems. The invariant form of the convergence criterion of the multipole expansion is given and discussed.
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  • 95
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    International Journal of Quantum Chemistry 15 (1979), S. 717-729 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Power moments for all of the reduced hydrogenic Green's functions have been computed. These moments have the same form as the corresponding moments of the free-particle Green's functions. Green's functions of the second kind are defined, and uses for these objects in model potential theory and the theory of many-body Green's functions are pointed out. In the case of the ground state of the hydrogenic atom, the Green's function of the second kind has been given.
    Additional Material: 1 Ill.
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  • 96
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    International Journal of Quantum Chemistry 15 (1979), S. 745-750 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Different kinds of improved uncoupled Hartree-Fock methods are proposed for the calculation of second-order perturbation energies. Using these methods inequalities are derived for the error of the uncoupled procedure with geometric approximation.
    Additional Material: 1 Tab.
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  • 97
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    International Journal of Quantum Chemistry 15 (1979), S. 731-744 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The use of multiple scattering techniques combined with a statistical exchange potential for the description of the electronic structure of atoms, molecules, and solids depends strongly on the geometry (muffin tin, overlapping spheres, or cellular potentials) and on the form of the electron gas exchange. In this work we compare only the effects of using different geometries. For that purpose we have done calculations on the hydrogen molecular ion and Hartree-type calculations on the hydrogen molecule so that no exchange effects are involved. To avoid arbitrariness in the choice of the sphere sizes we propose a nonempirical criterion that consists of using the set of radii that will minimize the charge in the interstitial region of the molecule or cluster. Some arguments are given to justify this criterion, and to clarify the differences between cellular, overlapping spheres, and muffin-tin geometries. It is found that the cellular geometry gives a very good description around the equilibrium internuclear distance. However, for most systems of interest, exchange will be present. Thus, we have done, for comparison, the calculation on H2 using Xαβ statistical exchange. It is shown through this calculation that some of the correlation energy may be obtained by redefining the molecular orbitals in terms of non-paired-spins spatial orbitals, this formulation being required to obtain the correct free-atom limit.
    Additional Material: 6 Ill.
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  • 98
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    International Journal of Quantum Chemistry 15 (1979), S. 751-767 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The theory of the open-and closed-shell restricted Hartree-Fock method is given a unitary group formulation. Both extremum and stability conditions are employed, the former leading to a generalized Brillouin theorem.
    Additional Material: 2 Tab.
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  • 99
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    International Journal of Quantum Chemistry 15 (1979), S. 769-782 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An improved interaction potential has been devised for diatomic alkali halide molecules. This potential, in addition to similar attraction terms as in the Rittner potential, includes a new exponential for the short-range repulsion. The constant m in the exponential is seen to be well expressible in terms of the parameters of the Rittner potential. The new potential is also correlated with different properties, as for example, effective charges, effective radii, effective principal quantum numbers, etc., of the combining ions. Various spectroscopic constants, viz., the ionic dissociation energy Di, the vibrational-rotational coupling constant αe, the vibrational anharmonicity constant ωexe, as well as two second-order spectroscopic constants γe and βe have been calculated for this and for the Rittner potential. From comparisons between these two potentials, the new one has been observed better than the other.
    Additional Material: 3 Tab.
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  • 100
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    International Journal of Quantum Chemistry 16 (1979) 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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