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  • Digitale Medien  (853)
  • 1980-1984
  • 1970-1974  (853)
  • 1925-1929
  • 1890-1899
  • 1971  (853)
  • Cell & Developmental Biology  (405)
  • Chemical Engineering  (386)
  • Engineering General  (62)
  • Nuclear reactions
Materialart
  • Digitale Medien  (853)
Erscheinungszeitraum
  • 1980-1984
  • 1970-1974  (853)
  • 1925-1929
  • 1890-1899
Jahr
  • 101
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The earliest visible changes that occur in the normal organization of the lens epithelium after a penetrating wound in the lens suggest that passage of an injury stimulus outward from the wound occurs within the first half day after injury: changes in normal tissue architecture appear near the wound at six hours and move outward to involve the proliferative zone by 12 hours. This is followed by migration of cells toward the wound. There is a slight increase in cell number in the proliferative zone within the first day, followed at later intervals by a decrease there and a concomitant increase in cell number adjacent to the wound. After a pre-injury injection of H3-TdR (or I125-UdR), labeled cells that had incorporated the precursor in the normal proliferative zone were found progressively closer to the wound with increasing time. Only the cells which incorporated the radioactive tracer could be followed, but it is likely that cells in the central areas also migrated toward the wound since they showed spindling and superimposition. Migration of cells into the wound margins is an important phase of wound closure which begins long before the major productions of new cells by mitosis.
    Zusätzliches Material: 1 Tab.
    Materialart: Digitale Medien
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  • 102
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Morphology 133 (1971), S. 457-493 
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The sexual apparatus was studied in 100 adult axolotls (Siredon mexicanum) for 13 different spawnings. The ages of the animals varied between two and six years. Additional material from Indiana University was also studied. Altogether there were 55 female and 52 male adult axolotls represented. The purpose of the study was to investigate the limits of the variations occurring in normal axolotls and to compare the incidences of variations and developmental abnormalities in adult animals of both sexes at various ages and belonging to different strains.Among the 13 spawnings examined, five strains were completely normal in 100% of the animals, but the remaining eight strains all included abnormal animals. The incidence of abnormal animals in some of these latter strains was 40% or even 50%. Since all of the animals were under the same conditions, the variability and the occurrence of developmental abnormalities most likely depended upon hereditary factors. Among 55 females, only seven (12.7%) were abnormal; only four of these had developmental abnormalities, and only one was hermaphrodite. Among 45 males from the author's axolotl colony, 16 (28%) were abnormal. Of these latter, six had no sex cells or very few; this variation must be regarded as a developmental abnormality. All of these malformations resulted from major degeneration processes and abnormal morphogenesis.Arrested development was also observed in many males. Spermatozoa were completely absent from the testes of eight animals. In the additional material from Indiana University (testes from 7 males), there was also one completely abnormal testis with major degeneration processes and complete absence of sex cells. It is evident that variability and the incidence of developmental abnormalities in the sexual apparatus in adult axolotls of some strains are very great.
    Zusätzliches Material: 3 Tab.
    Materialart: Digitale Medien
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  • 103
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Morphology 134 (1971), S. 21-45 
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The sensillum of the ear of Feltia subgothica contains two ciliated receptor cells, the A cells. The cilium of each is enclosed within a well developed scolops consisting of a cap, a set of scolopalial rods and a collar, an unusual structure contained within the dendrite. The tip of the cilium is inserted in a channel in the scolopalial cap.The cap is linked to the tympanic membrane by a series of three structures: a cap cell, a microtubular shaft and a microfibrillar plug. The two latter structures are heavily reinforced by cytoskeletal elements and the microfibrillar plug is actually continuous with the tympanic membrane. These three structures transmit the vibration of the tympanic membrane to the scolops.The simplicity and accessibility of the ear suggests that it might be a good system in which to investigate cellular events associated with transduction of sound in these receptors.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 104
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Morphology 134 (1971) 
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Materialart: Digitale Medien
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  • 105
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Morphology 134 (1971), S. 181-194 
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: In Bombyx mori the male is the homogametic sex, crossing over occurs only in males, and chiasmata are observed in spermatocytes, but not in oocyte nuclei. If the assembly of synaptonemal complexes is an essential prerequisite for genetic crossing over and chiasmata formation, then the nuclei of Bombyx spermatocytes should contain synaptonemal complexes. Synaptonemal complexes were found in spermatocytes from young four instar larvae. The structure of meiotic bivalents is described using micrographs taken with 100 and 1000 KV electron microscopes. These data together with that from the literature are used to construct a three-dimensional model of the synaptonemal complex and to suggest its method of origin and its function during crossing over.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
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  • 106
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Morphology 134 (1971), S. 215-241 
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Queen butterflies do not mate until the male has brushed the tufts of his scented, abdominal “hairpencils„ over the female's head and antennae. The trichogen cells located at the base of each hairpencil are secretory. Presumably, these cells produce the sex pheromone necessary for mating. The liquid secretion must move from a central, microvillus-lined vesicle through the cuticle of the hairs to coat numerous, free, cuticular „dust“ particles which adhere to the hairs' surface. The dust carries the secretion to or near the female's antennae. In the pupal stage the dust particles develop as outpocketings of the hair epicuticle. An amorphous matrix, probably protein epicuticle, is deposited in the outpocketings between the cuticulin layer and plasma membrane of the hair. Before the butterfly emerges from the pupa the matrix becomes enclosed by cuticulin, and the particles pinch off from the hair.
    Materialart: Digitale Medien
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  • 107
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Light microscopy of serially sectioned nasopalatine duct remnants in ventral rostral integument of four adult (2 ♂, 2 ♀) fin whales reveals: (1) a common structure in all, (2) blindly ending nasopalatine pits 4 to 9 mm deep, (3) solid epithelial duct remnants 12 to 15 mm long, (4) lack of chemoreceptor endings, and (5) an abundance of presumed mechanoreceptors, mostly of the Pacinian category on the adoral sides, but also including some thinly encapsulated and perivascular ones that extend into the abundant connective tissue papillae of the duct remnants. Comparative and evolutionary relations of these structures are discussed.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
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  • 108
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Morphology 134 (1971), S. 281-313 
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: A morphohistological study was carried out on the pineal organ in 15 species of teleosts belonging to 12 different families. In spite of a general similarity in pineal structure in different species, there is evident a systematic diversity. The majority of species possess saccular pineal organs containing photoreceptors as prominent parenchymal components. The close anatomical relationship of the pineal organs with the relatively thin cranial roof further supports the photosensory nature of this organ in most species. However, in certain species, particularly Corydoras aneus, apparent paucity of sensory cell outer segments, parenchymal proliferation, epithelial compactness and rich vascularization suggest specializations for a predominantly nonsensory and possibly secretory function. On the other hand, the preponderance of sensory cells in the pineal organ of Symphysodon aequifasciatus and Gyrinocheilus aymoneri indicates exceptional adaptitions for a predominantly photosensory role. The results are discussed in the light of existing electron microscopic and biochemical investigations which support a secretory function of fish pineal. The need for proper selection of species for future research on pineal function is emphasized.There is also evident a close anatomical relationship between the pineal organ, the dorsal sac and the third ventricle in various species. The possibility of intramural functional relationship of the pineal with these structures and the brain is suggested.The presence of intrapineal neurones and an afferent (pinealofugal) innervation in majority of species is described. The tractus pinealis enters the posterior commissure area. In rainbow trout, Salmo gairdneri, some branches, right and left, leave the posterior commissure and could be seen to move toward the habenular ganglia. Their destination remains unclear. In jack smelt, Atherinopsis californiensis, a major bundle of tract fibres follows the ventral aspect of the posterior commissure reaching what may be nuclei dorsomedialis-dorsolateralis. The possibility of direct connections with the fasciculus retroflexus is suggested. No evidence could be provided supporting existence of an efferent (pinealopetal) innervation of parenchymal cells in the pineal of species studied. It is pointed out that clarification of this aspect in future is important for a proper understanding of metabolic aspects of pineal organs in fishes.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
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  • 109
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The structure, attachment and subsequent metamorphosis of larvae of the marine bryozoan Bugula neritina were studied by light and electron microscopy.Two points of larval anatomy are of special significance to proper interpretation of the metamorphosis: 1Two cytologically similar blastemal tissues, each laden with free ribosomes, occur as parts of the apical organ complex. The upper blastema directly contacts the larval surface, forming the non-ciliated rows of the apical organ. The lower blastema is internal and is oral to and contiguous with the upper blastema.2The epidermal tissues of the larva are joined in the following sequence, beginning at the aboral pole: a. apical organ complex; b. apical-connecting cell; c. infolded pallial sinus epithelium; d. vesicular-connecting cell; e. aboral vesicular epithelium; f. corona; g. oral vesicular epithelium; and i., j., and k. internal sac neck, wall and roof regions.The initial stages of metamorphosis involve a complex sequence of morphogenetic movements, including: 1eversion of the internal sac, permanently attaching the larva to the substrate;2inrolling of the aboral vesicular epithelium, corona, oral vesicular and ciliated epithelia, and neck region of the internal sac into the larval interior; concomitantly the pallial sinus epithelium evaginates;3loss of connection between the invaginated tissues and the surface;4fusion of the pallial sinus epithelium with the wall region of the internal sac, maintaining the integrity of the body surface;5retraction of the apical organ complex and invagination of the pallial sinus epithelium with the simultaneous elevation of the internal sac wall region to the aboral pole.At the conclusion of these events the preancestrular surface is covered by the wall and roof regions of the internal sac. Cells of the wall region form the epidermis of the body wall except for the attachment disc and secrete a cuticular exoskeleton that is secondarily calcified; the attachment disc is formed by the roof region of the internal sac.Internally, the ectodermal upper blastema differentiates into the lophophore and digestive tract of the ancestrular polypide, while the lower blastema forms the lining of the lophophoral coelom and the splanchnic (but not the somatic) lining of the visceral coelom. The visceral somatic peritoneum is formed from cells that may originate from the mesodermally derived pigmented cells of the larva to which they are similar in pigmentation and cytology. Such a composite derivation of a coelomic lining has not been described previously.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
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  • 110
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Morphology 135 (1971) 
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Materialart: Digitale Medien
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  • 111
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Morphology 134 (1971), S. 479-487 
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Smears of Orconectes virilis hemolymph were prepared by fixation in 10% formalin immediately upon withdrawal, and after an interval of 1, 5, or 15 minutes. These smears were then stained by a variety of histochemical means designed to identify a material which is released from both hyaline and granular cells during the coagulation process. Based upon reactions to various carbohydrate, lipid and protein tests, this material appears to consist of a glycoor muco-protein, and its localization and activity coincide with the „fibrin ferment“ described by Hardy (1892). Its release is probably initiated from the hyaline cells, followed shortly thereafter by a similar activity of the granulocytes. While it cannot be ascertained by the methods used in this study whether or not this material participates actively in clotting, its release is nevertheless coincidental with coagulation.
    Zusätzliches Material: 1 Tab.
    Materialart: Digitale Medien
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  • 112
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Morphology 135 (1971), S. 13-50 
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The ectethmoid-mandibular articulation in Melithreptus and Manorina (Meliphagidae: Aves) consists of the dorsal mandibular process fitting into and abutting against the ventral ectethmoid fossa; it forms a brace for the mandible. This articulation in Melithreptus is a typical diarthrosis with long folded capsular walls. The mandible, thus, has two separate articulations, each with a different axis of rotation. No other genus of Meliphagidae (except Ptiloprora) or any other avian family possesses a similar feature.The jaw and tongue musculature of Melithreptus are described. The two muscles opening the jaws are well developed, while those closing the jaws are small. The tongue muscles show no special developments.A large maxillary gland, presumably muscus secreting, covers the ventral surface of the jaw muscles. Its duct opens into the oral cavity just behind the tip of the upper jaw. The frilled tip of the tongue rests against the duct opening.The ectethmoid-mandibular articulation braces the adducted mandible against dorsoposteriorly directed forces. The mandible can be held closed without a compression force exerted by the mandible on the quadrate, permitting the bird to raise its upper jaw with greater ease and less loss of force. The tongue can be protruded through the slight gap between the jaws, moving against the duct opening and thus be coated with mucus. Presumably, these birds capture insects with their sticky tongue. Hence, the ectethmoid-mandibular articulation is an adaptation for this feeding method; it evolved independently in three genera of the Meliphagidae.The ectethmoid-mandibular articulation demonstrates that a bone can have two articulations with different axes of rotation, that the two articular halves can separate widely, and that articular cartilages can be flat and remain in contact over a large area. Its function suggests that the basitemporal articulation of the mandible found in many other birds has a similar function. And it demonstrates that in the evolution of the mammalian dentary-squamosal articulation, the new hinge did not have to lie on the same rotational axis as the existing quadrate-articular hinge.
    Zusätzliches Material: 16 Ill.
    Materialart: Digitale Medien
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  • 113
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Spermatozoa in the head of the epididymis of the flying squirrel have large cup-shaped acrosomal heads with two ventral ridges. The cytoplasmic droplet contains an ovoid body and a group of large granules. These structures may be related to the chromatoid body of spermatids. The spermatozoa form polarized cylindrical bodies with centrally placed tails and peripheral heads. The tips of acrosomes protrude into concavities of acrosomal cups of neighboring spermatozoa. Peripheral portions of acrosomes are in contact with microvilli (stereocilia) of epididymal cells. Polarized cylindrical bodies are present in five species of Sciuridae.
    Materialart: Digitale Medien
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  • 114
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Morphology 135 (1971), S. 153-163 
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Fine structure of the carp torus longitudinalis was studied by electron and light microscopy and compared with the granular layer of the carp cerebellum. There are three types of cells in the torus longitudinalis, that is, small, medium-sized and large cells. From the small cells to the medium-sized cells, there is gradual transition in size and in the amounts of cell organelles. These cell profiles and the closely packed cell pattern in a part of the torus longitudinalis are quite similar to those in the granular layer of the cerebellum. Moreover, peculiar synaptic configurations of so-called “synaptic glomeruli” are found both in the torus longitudinalis and in the granular layer of the cerebellum. In the torus longitudinalis, unmyelinated nerve fibers are seen to have bulbous swellings along their course, most of which contain a mitochondrion, as do they in the carp tectum opticum.It is speculated that the torus longitudinalis may be partly related to the granular layer of the cerebellum and partly to the tectum opticum.
    Zusätzliches Material: 17 Ill.
    Materialart: Digitale Medien
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  • 115
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: In muskellunge blastulae the yolk sac syncytium originally contains nuclei comparable in size to the blastomere nuclei from which the syncytial nuclei arose. By mitosis the originally diploid syncytial nuclei become numerous and crowded together. Continued synchronous mitosis of neighboring syncytial nuclei and the resultant crowding together of their spindles culminates in overlapping spindles, multipolar spindles, disorganized spindles, and the crowding together of large numbers of condensed chromosomes from contigous spindles. When such an aggregation of condensed chromosomes becomes enclosed within one nuclear membrane, a giant nucleus appears in the following interphase. It soon becomes postmitotic.
    Zusätzliches Material: 16 Ill.
    Materialart: Digitale Medien
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  • 116
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Morphology 134 (1971), S. 383-397 
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The typical eupyrene and atypical apyrene cycles of sperm differentiation in Bombyx mori were studied, with special attention to centriole number and behavior. Contrary to other reports, there is always only one centriole in the differentiating and in the mature sperm, thus confirming our previous findings that insect sperm has one centriole at the base of the flagellum, in contrast to two centrioles found in many other groups of animals. This numerical difference is discussed in an evolutionary context.
    Zusätzliches Material: 17 Ill.
    Materialart: Digitale Medien
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  • 117
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Examination of the cardiac anatomy of lizards of the family Varanidae revealed that much of the previous literature contained basic errors both in description and interpretation. These are corrected and terminology of various authors is standardized.The varanid ventricle is similar to that of most other lizards in not being elongated, in having the base at right angles to the longitudinal axis, and in having the vertical septum weakly developed. However, it is not a typical lacertilian heart in that it has a number of characteristic ophidian features such as a muscular cone surrounding the cavum latero-dorsale and a prominent twisting of the cava. It lacks a gubernaculum cordis and a cartilaginous rod in the septum aortico-pulmonale, both of which are present in many non-varanid lizards, but seldom occur in snakes. The location of the heart is more posterior in the body than is true of other lizards.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 118
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Morphology 134 (1971), S. 425-435 
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Recent hypotheses about the mechanisms of adaptation of bone to impressed mechanical forces differ according to the extent to which tensile stresses are thought to be functionally important in bone. A pilot study of three anatomical regions by means of the photoelastic analogy suggests the possibility that net tension rarely exists in significantly large regions of bones during normal function.Thus the examination of two situations (opposite linear attachment of muscles to the lips of bony crests and opposite areal attachment of muscles to either side of thin bony plates) suggests that in rare cases where precise anatomical architecture is such that net tension may be present, then bone is not found; such regions consist of appropriate collagenous structures.In the third situation (opposite attachment of tendons to a sesamoid bone) where it would appear that net tension ought to exist, it is suggested that it is likely that it does not. Net tension probably occurs only in tendons running in tightly curved bony grooves: those very situations where sesamoid bones are not present.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
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  • 119
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Morphology 134 (1971), S. 437-445 
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The left and right afferent nerves to the corpus cardiacum contain approximately 50 and 90 axons, respectively, when they enter the gland. Both bifurcate within the gland, so that four nerves leave the corpus cardiacum. These, however, contain a total of 90 axons. Of the 50 axons unaccounted for 30 are believed to terminate in the corpus cardiacum and 20 in the corpus allatum. The corpus cardiacum contains 12 intrinsic neurosecretory cells which are disposed laterally with respect to the extrinsic axons. Many of these contain neurosecretory spheres and presumably originate in the brain. The intrinsic corpus cardiacum cells also contain neurosecretory granules, and they produce short cytoplasmic processes which interdigitate with the extrinsic axons.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
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  • 120
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Morphology 133 (1971), S. 1-15 
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The pineal organ of the bluefin tuna was studied using light and electron microscopy. The pineal, an evagination in the diencephalic pallium, consists of a distal expanded end-organ and a stalk. A pineal nerve connects this end-organ to the habenular area of the diencephalon. The tissues above the pineal are modified for light transmission. Supporting cells are the most numerous type seen in the pineal tissue. The cytoplasm often contains glycogen, while the golgi apparatus is seldom seen. The plasma membrane is a complex of folded membranes interdigitating with adjacent cells. The sensory cells are characterized by a basal nucleus, a constricted neck region, and an ellipsoid region that is capped distally by lamellae. Sensory cells have the basic appearance of retinal photoreceptors. The lamellae are more disorganized than those of retinal rods, and some lamellae appear to be discharged from the cell.This study indicates that the pineal may function to deliver photoperiodic stimuli to the central nervous system, through the transmission of nerve impulses.
    Materialart: Digitale Medien
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  • 121
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Morphology 133 (1971), S. 105-123 
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The endodermal nerve nets of the scyphozoan jellyfish Phacellophora camtschatica and Cyanea capillata were stained with methylene blue. Small animals (3-7.5 cm in diameter) stained easily. The endodermal nerve net of both species is a synaptic net consisting of bipolar and some few tripolar nerve cells with unbranched neurites. The neurites terminate on other neurites. Very few free nerve endings were observed. The neurites have a diameter of 1/4-1/2 μ and there is no indication of the presence of neurites too fine to be followed in the light microscope.The gross appearance of the net changes with the size of the medusa. Staining 15-53 cm diameter animals showed that the nerve cells increase in size with the size of the animals, that the density of the nerve net decreases.The endodermal nerve net is very similar to our interpretation of the Diffuse Nerve Net of the ectoderm but without the typical primary sense cells. In both cases the appearance of branching neurites is interpreted as an artifact caused by neurites terminating on other neurites.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
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  • 122
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Adult newts placed in an atmospheric environment of 85% oxygen, saturated humidity, and at a temperature of 20 ± 1°C survived particularly well a 44-day test period. They did not succumb to “oxygen toxicity” as has been frequently reported for other vertebrate species.Having established the newt's tolerance of high oxygen atmosphere, the effect of oxygen on growth and development in the regenerating newt limb was investigated. Under the atmospheric conditions described above, and under 92% oxygen, the regeneration of adult newt limbs appeared to be retarded during the first 25 days after amputation when compared with regenerating limbs of control animals kept under a normal atmosphere of 21% oxygen (air). Thereafter, little or no difference could be discerned between the regeneration of experimental and control limbs.It is known that molecular oxygen participates directly in the hydroxylation of proline to hydroxyproline in the synthesis of collagen. Sectioned regenerates stained specifically for collagen were examined to determine if collagen synthesis was induced in experimental animals. Two regeneration-inhibited limbs of oxygenated newts showed cicatrical repair of the apical limb stump 25 days after amputation. However, the majority of the experimental animals revealed no obvious increase in collagen fibers.These results contraindicate any marked “oxygen toxicity” affecting the life of the newts, or regeneration of their limbs. It is suggested that a change in collagen fiber type might have been induced by the high-oxygen atmosphere. Investigations to test this hypothesis are currently underway.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
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  • 123
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The morphology of the Weberian ossicles of Astyanax mexicanus, an eyed river fish, and A. jordani, the Mexican blind cave fish, was investigated and the results were correlated with behavioral data on the auditory capacities of the two species. Several characteristics of the ossicles of the two species were inter-specifically significantly different while other characteristics varied as much intra-specifically as inter-specifically. The ascending arm of the scaphium was shorter in the blind fish than in the river fish and the ascending arm of the intercalarium was further from the distal end of the base of the bones in the blind fish than in the river fish.A previously unreported ligament between the scaphium and the sinus atrium impar was found in Astyanax. It was hypothesized that this connective tissue retained perilymphatic fluid within the inner ear, helped the ossicles return to an anterior position after moving posteriorly, and might protect the inner ear during intense acoustical stimulation.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
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  • 124
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Morphology 133 (1971), S. 241-251 
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Changes with age in bone cortex of the rat were investigated by establishing histological parameters which could be quantitated to estimate age at death. Decalcified cross sections of mandible, femur and tibia were prepared from rats two to 120 days old, and measurements were made of: (1) number of osteons, (2) average number of lamellae per osteon, (3) average Haversian canal diameter, and (4) number of non-Haversian (primary) canals. Multiple regression techniques were used to estimate age at death from several combinations of these variables.With age, the number of osteons per unit area of bone and the number of lamellae per osteon increased, but Haversian canal diameter and the number of primary canals decreased. Multiple regression analyses indicated that age at death could be estimated to ± 3 days of the true value in 95% of the cases. Nomographs based on histological measurements of each bone were prepared which can provide accurate estimates of age between two and 120 days in the Sprague-Dawley female rat. It was concluded that microstructure of bone cortex can not only be quantitated to provide accurate estimates of age but it may also constitute a sensitive measure of the metabolic state of the organism. The techniques utilized should prove useful in anthropology as well in studies of bone aging.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
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  • 125
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Morphology 133 (1971), S. 253-271 
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The distribution of glycogen, lipids and succinic dehydrogenase (SDH) in twitch and tonus fibers of several amphibians and birds is described, and the correlation of histochemical properties with fiber structure and function is discussed. Twitch and tonus fibers were identified histologically by the presence of Fibrillenstruktur and Felderstruktur respectively. The rectus abdominis, sartorius and semitendinosus were studied in Rana pipiens, Xenopus laevis and Necturus maculosus; the pectoralis major, pectoralis minor, anterior latissimus dorsi and posterior latissimus dorsi were investigated in Gallus gallus and Passer domesticus. Periodic acid-Schiff was used to stain for glycogen, Sudan Black B for lipids and Nitro BT for localization of SDH activity.In amphibian muscles, fibers with Fibrillenstruktur and Felderstruktur constitute the rectus abdominis. Except in one case, only Fibrillenstruktur fibers were seen in the sartorius and semitendinosus. In the avian muscles, fibers with Fibrillenstruktur comprise the pectoralis major, pectoralis minor and posterior latissimus dorsi, while fibers with Felderstruktur constitute the anterior latissimus dorsi. These types of muscle fibers showed no consistent pattern in the distribution of glycogen, lipids and SDH. The evidence precludes the use of such data alone for distinguishing twitch (Fibrillenstruktur) and tonus (Felderstruktur) fibers.
    Zusätzliches Material: 1 Tab.
    Materialart: Digitale Medien
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  • 126
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Morphology 133 (1971), S. 319-337 
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The fine structure of the excretory tubes of the mesostigmatid mite Macrocheles muscaedomesticae were investigated. These paired tubes are partially ensheathed by fat body and invested throughout by a branching system of visceral muscles. The fine structure of the cells of the excretory tube is in general similar with only minor differences found throughout its length. The basal region of each epithelial cell of the excretory tube borders the hemocoel and is divided into many compartments by the extensive infolding of the plasma membrane. Mitochondria and vacuolar inclusions are often closely associated with these compartments. More than one morphological type of mitochondria was found distributed throughout the cells of the excretory tubes. The most commonly encountered type had well developed cristae and an electron dense matrix. Less commonly, mitochondria with somewhat poorly developed cristae and a translucent matrix often containing myelin-like figures of varying complexity were observed. It is suggested that they represent part of a normal process of mitochondrial degeneration. The apical region of the cell has a border composed of plate-like folds of the plasma membrane termed microlamellae. The lumen contains abundant granules of the excretory product.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
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  • 127
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Morphology 133 (1971), S. 375-386 
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The fine structure of the developing gizzard of the chick embryo has been studied to define the sequence of events in cytodifferentiation of the epithelium and to look for morphological evidence of epithelio-mesenchymal interaction. During the fourth day of incubation epithelial cells begin to form mucous secretory granules, later massive glycogen deposits appear, and finally by day 8 numerous cell processes have formed. Tissue was prepared by a number of methods to stain material associated with cell surfaces. At the time induction is presumbably occurring such stainable material is abundant. Epithelial and mesenchymal tissue components when cultured transfilter show no inductive effects and stainable cell surface material is greatly reduced near the epithelium.
    Zusätzliches Material: 21 Ill.
    Materialart: Digitale Medien
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  • 128
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: An approximate 1:1 ratio of myelinated to unmyelinated fibers was established in counts from electron micrograph montages in nerves of the newt, Triturus (Notophthalmus) viridescens. The number of myelinated fibers correspond to the number counted with the light microscope after osmium fixation. Light microscope counts of silver impregnated sections yielded a value slightly higher suggesting that, except for bundles of unmyelinated fibers, the silver technique revealed mainly myelinated fibers. The results were used to reassess previous quantitative studies on the relation between number of nerve fibers and the control which nerves exert on regeneration. For a truer estimate of the number of axons affecting regeneration, fiber values previously reported should now be doubled to include the large number of unmyelinated fibers. However, calculations show that the unmyelinated fibers contribute less than 3% of the total neuroplasm in the peripheral nerve.Finally, counts made of Schwann cells and fibroblasts show that the latter are few in number.
    Zusätzliches Material: 4 Tab.
    Materialart: Digitale Medien
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  • 129
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Morphology 134 (1971) 
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Materialart: Digitale Medien
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  • 130
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Morphology 134 (1971), S. 1-19 
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: A histological study was undertaken of the differentiation of the lymphomyeloid complex of larvae of the common leopard frog, Rana pipiens, reared at 18-21 °C. Immature lymphocytes are first recognised in the thymus and pronephros at stage I of Taylor and Kollros ('46). By the end of stage II, small lymphocytes are regularly found among the predominant larger lymphoid cells in the thymus, in which corticomedullary differentiation has begun. At this time, a few small lymphocytes are also apparent in the ventral cavity bodies, lymph gland, pronephros, mesonephros and intestine, but rarely occur in the spleen. During stages III and IV extensive development of these components of the lymphomyeloid complex occurs. The organs now contain large numbers of mature lymphocytes and have attained states of differentiation that remain essentially similar in subsequent larval stages. By stage V, small epithelium-associated lymphoid accumulations are abundant throughout the length of the gastrointestinal tract. The anlagen of the procoracoid body and bone marrow appear just prior to metamorphosis.The kidneys are the main sites of blood formation in the larva. Masses of granulocytes are also usually found in the abundant ventral cavity bodies. A consideration of the roles of each of the organs provides insight into the ontogeny of the immune system of the Anura in general.
    Materialart: Digitale Medien
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  • 131
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Each chemoreceptor sensillum of Limulus polyphemus consists of 6-15 bipolar neurosensory cells with distal processes confined within a single cuticular tubule as they extend to the outside environment. The cuticular tubule, which is enveloped by the cuticulo-tubal cell, opens proximally into a fluid-filled extracellular space through which the dendrite passes before entering the cuticular tubule. Between the neurosensory cells are one to three microvillar cells also exposed to the extracellular space. This space is enclosed by a sheath cell extending proximally from the inner opening of the cuticular tubule and enveloping the proximal portions of the dendrites, the distal portions of the microvillar cells, as well as the distal portion of some neurosensory cell bodies. Most of the remaining portions of the neurosensory cells and microvillar cells are enveloped by neuroglia. Tight junctions occur between the distal portions of the dendrites in or near the cuticular tubule. Each dendrite has a cilium-like segment located where it traverses the extracellular space with a 9 + 0 pattern of fibers. Septuplelayered junctions occur among the proximal portions of some dendrites and some neurosensory cell bodies of the same sensillum. The subjacent processes of the sensillum frequently course proximally as isolated axons before joining nerve bundles. In the chilarial and gnathobasal chemoreceptors these nerve bundles course proximally to neuropile clumps of a peripheral nerve plexus. The presence of numerous synaptic vesicles in the neuropiles suggests that chemical transmission may occur among “en passant” synapses formed by the axons. Proximally the neuropiles are joined to the central nervous system by relatively long nerves.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
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  • 132
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Morphology 133 (1971), S. 303-317 
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: In the course of this investigation 24 fetuses of the Sprague-Dawley rats were used. Pregnant animals were sacrificed at 12, 14, 16, 18, and 20 days of gestation. The fetuses were removed and fixed in buffered formalin solution. The heads were dehydrated, embedded in paraffin, and the nasal cavities were sectioned serially. Light microscope observations were made on 10 to 15 μ thick sections stained with H and E, Mallory's trichrome stain, and Gomori's alkaline phosphatase stain. The 12 day old fetus possessed well developed olfactory depression with a thick epithelial covering. The olfactory fossa was still separated from the buccal cavity by a solid layer of young mesenchyme. In the 14 day old fetus the communication between the nasal and buccal cavities was established. The palatal shelves developed still vertically. All the turbinates and the nasal capsule were already differentiated. The glandular system was represented with the main and two to three accessory excretory ducts. During the sixteenth day of prenatal development, the sinus and the sinus related glands became for the first time evident. The ossification of the membranous parts of the lateral nasal wall was initiated. In the next two developing stages the maturation of the cartilage, the increasing ossification in the membrane, and the further differentiation of the glands were the major morphological changes in the formation of the lateral nasal wall.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
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  • 133
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Morphology 133 (1971), S. 339-352 
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The histogenetic and organogenetic capabilities of normal and lobeless embryos of Ilyanassa obsoleta are analyzed. Larvae developed from eggs in which the polar lobe was removed at the trefoil stage of first cleavage were studied in wholemount and section. None showed any evidence of eyes, statocysts, operculum, external shell, heart, or intestine. Sixty per cent of the wholemount larvae observed under polarized light exhibited internal masses of birefringent material resembling shell material. Of eight- to nine-day lobeless larvae studied as stained, sectioned material 100% possessed muscle tissue; 97.5% possessed velar tissue, digestive gland tissue, and style sac tissue; 52.5% possessed two or more style sac areas; 71% exhibited esophagus; 63% possessed stomach tissue; 37% exhibited stomodeal-like invaginations of the ectoderm; 31% exhibited a lightly staining ciliated area at the tip of the prevelar ectoderm; and 21% possessed glandular ectoderm resembling pedal or mantle gland tissue.The evidence presented suggests that the material of the polar lobe has an important role not only in cellular differentiation but also in the organization of tissue types into organs or organ primordia.
    Materialart: Digitale Medien
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  • 134
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Morphology 134 (1971), S. 47-55 
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: An electron microscopic investigation was made of the origin and morphology of the canal system that connects sister spermatocytes of larval Bombyx mori. Canal formation results from incomplete cleavages during the mitoses which immediately precede meiosis. We suggest the lip which surrounds each canal is derived from the contractile ring which is prevented from constricting completely by interaction with the midbody. Cells were found with as many as four canals which demonstrates that canal rims can persist through a number of mitotic cycles. Speculations are advanced as to the significance of these canals in restricting gonocytes from unlimited divisions.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
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  • 135
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Morphology 134 (1971), S. 91-103 
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Adult and nymphal antennae of the cockroach, Leucophaea maderae, contain nine or more different morphological types of sense organs. There is no outwardly apparent sexual dimorphism in adult antennae. Nymphs are dificient in gross numbers of sensilla. Sense organs are classified morphologically by their similarity to known types of sensila and are assigned functions on this basis and preliminary electrophysiological data: Sensilla chaetica (A), thick-walled mechanoreceptive hairs in groups on the antennal base; S. chaetica (B), thick-walled setae which are tactile and probably chemoreceptive, occurring in the antennal base and flagellum; S. trichodea (A), thin-walled chemoreceptive hairs of the flagellum; S. trichodea (B), minute hairs on the scape and pedicel; S. basiconica, thin-walled chemoreceptive pegs, and S. coeloconica („pit-pegs“) of the flagellum; S. campaniformia and scolopidia, mechanoreceptors in the base and flagellum; plus Johnston's organ and/or connective chrodotonal organs in the pedicel. Calculations based on absolute counts of sensilla and their known innervation yield an estimate of about 3.3 × 104 sensilla and 105 cells per antenna.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 136
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Morphology 134 (1971), S. 131-140 
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The carp, Cyprinus carpio, was found to have eight pairs of muscles inserting on the pharyngeal bones. These were the levator arcus branchialis V, retractor os pharyngeus superioris, retractor os pharyngeus inferioris, cleithropharyngeus superficialis, cleithropharyngeus profundus, coracobranchialis posterior, transversus ventralis V and subarcualis rectus communis. Complete morphological descriptions of the muscles are given along with relevant osteological information. The pharyngeal muscles function in mastication by moving the bones and their attached teeth against the chewing pad so that crushing and grinding of food occurs during occlusion. In addition, certain pharyngeal bone muscles enlarge the lumen of the posterior pharynx thereby admitting food to the region of the teeth and chewing pad. The homologies of some of these muscles are considered along with the historical details pertinent to the establishment of a suitable nomenclature for the pharyngeal bone muscles.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
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  • 137
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The hypothalamus of the opossum (Didelphis virginiana), the armadillo (Dasypus novemcinctus mexicanus), and the cat (Felis domestica) was studied using Del Rio Hortega's silver carbonate technique, as modified by Scharenberg ('60). This technique demonstrates astrocytes, oligodendroglia, and neuronal perikarya, but does not impregnate microglia. The morphology of macroglia was observed in ten comparable nuclei in each of the three species. The subpial and subependymal areas were also examined.Astrocytes display more cell body angularity and have more processes in most hypothalamic regions of the cat when compared to similar regions of the opossum and armadillo.In the anterior hypothalamic nucleus, the ventromedial and the dorsomedial hypothalamic nuclei, and the medial mammillary nucleus of all three species, astrocytes send processes to neurons, but neuronal and astrocytic perikarya are usually not directly contiguous. However, oligodendrocytes in a perisomatic position on neurons are a consistent feature in these nuclei.A closer relationship appears to exist between astrocytes and neurons in the neurosecretory nuclei. In the supraoptic nucleus and paraventricular nucleus of all three species a basket-like structure, designated a „pericellular envelope“ was observed surrounding neuronal perikarya. This structure is composed of astrocytic and oligodendroglial cell bodies and processes, and is most highly developed in the cat.A dense astrocytic plexus was observed in the suprachiasmatic nucleus of the cat, and in the comparable nuclei of the armadillo and opossum. The most prominent macroglial cell type of the lateral hypothalamic and lateral mammillary nuclei of all three species is the interfascicular oligodendrocyte. The posterior hypothalamic nucleus of each species has many perisomatic oligodendrocytes, and in the armadillo and cat astrocytes are closely related to the larger neurons.A subpial plexus, consisting of a palisade of small glial cells with many processes, is present in the hypothalamus of the three species. Ependymal cells have long projecting processes throughout the length of the third ventricle in the armadillo hypothalamus, but such processes are only apparent in the region of the infundibular nucleus and median eminence in the opossum and cat.
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  • 138
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Morphology 134 (1971), S. 243-257 
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: This paper reports the demonstration, using fluorescence microscopy, of nucleolar DNA in two species of Drosophila. In Drosophila fulvimaculoides, the nucleolar DNA presents a variable morphology, suggestive of puffing activity. This material, which sometimes shows a banded structure like that of the polytene chromosomes, is shown not to be coextensive with the Y chromosome. Nucleolar DNA is demonstrated in Drosophila tumiditarsus also, and previous reports of an association of the dot chromosome with the nucleolus in this species are confirmed. The special usefulness of these two species for various sorts of investigation in pointed out.
    Materialart: Digitale Medien
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  • 139
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Striated visceral muscle cells are scattered singly or in small groups at the base of the intestinal cells of the mid-gut of Drosophila melanogaster larvae. Fibers less than 1 μ in diameter, designated as small, contain a single myofibril, few, if any, dyads and few mitochondria. Fibers of somewhat larger diameter contain dyads and more mitochondria. Both types of fiber have a perforate Z band which appears as discontinuous bodies in longitudinal sections and as a perforate sheet of dense rims and clear perforations in transverse sections. The Z rims contain filaments, 30 to 50 Å, oriented in the transverse direction. The number and arrangement of myofilaments and the ultrastructure of the Z band are consistent with the function of these muscles.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
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  • 140
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Morphology 135 (1971) 
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Materialart: Digitale Medien
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  • 141
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Morphology 135 (1971), S. 259-272 
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The segmental anatomy of Harmothoë imbricata deviates from the plan of a typical errant polychaete only slightly. The body is partitioned into 37 nonmetameric segments and is covered by 15 pairs of elytra. The segmental musculature consists of paired dorsal and ventral longitudinal muscles, pairs of dorso-ventral muscles, and in places the external surface of the worm is covered by a sheet of circularly coursing muscle fibers subjacent to the cuticle. The dorsal tubercles, elytrophores, cirratophores and ventral cirri are moved by muscles derived from segmental and intrinsic parapodial muscles. From the anatomy it is surmised that the lateral bending of the worm during swimming is due to cycles of activity involving the longitudinal muscles (S-waves). During a cycle of parapodial stepping, parapodial levators and promotors raise a parapodium from the substrate and direct it forward (the recovery stroke), at which time the muscles of the aciculum and setal sacs withdraw the neuropodial setae. During the power stroke parapodial depressors and remotors bring the tip of the parapodium against the substrate, applying a forward thrust and the neuropodial setae are extended. At the conclusion of the power stroke, the recovery stroke begins anew.
    Zusätzliches Material: 12 Ill.
    Materialart: Digitale Medien
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  • 142
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Morphology 135 (1971), S. 309-321 
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Subcapsular cells lining the thymic stroma vary from low to high forms, while others have a hemocytoblastoid aspect. The purpose of the present study was to establish whether the transformation of the low forms into hemocytoblastoid subcapsular cells can be induced by an antigen. Rats given 10 Lf of diphtheria toxoid intramediastinally were killed at periods ranging from 3 to 24 hours later. Other rats were injected with 3H-thymidine at various intervals after the toxoid injection, and were killed one hour later. The observations revealed a rapid hemocytoblastoid transformation of subcapsular cells following administration of the toxoid. The transformation is detectable as early as three hours after the injection and can be completed after nine hours. Radioautography revealed that DNA duplication is initiated rapidly in the transforming subcapsular cells, since it can be completed 9 to 12 hours after the toxoid injection. Other observations suggested the transformation of reactive perithymic fibroblasts into subcapsular cells as well as the transformation of hemocytoblastoid fibroblasts and subcapsular cells into free hemocytoblastoid cells.
    Materialart: Digitale Medien
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  • 143
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. 3-4 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Enthalpies of the coexisting equilibrium vapor and liquid mixtures of the ethane-n-butane-n-pentane system are computed at several pressures. Saturated liquid enthalpies are obtained by using a new multicomponent Clapeyron equation with the B-W-R equation of state and the experimental temperature-composition data for the ternary mixture. Saturated vapor enthalpies are calculated by applying the B-W-R equation to the vapor mixture. Ideal gas state enthalpies are used in both vapor and liquid enthalpy calculations.
    Zusätzliches Material: 1 Tab.
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  • 144
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. 30-37 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: For certain classes of chemical reactions, it is possible to increase the yield of the desired products by choosing appropriate variable-volume operating policies. An analysis of the steady state and semibatch operation of a stirred tank reactor demonstrates operating policies for both the isothermal and adiabatic case to maximize the steady state yield and to produce an improved semibatch yield. Computations carried out by using an analogue computer with a digital logic expansion system demonstrate further relationships between yield increase and operating policy.
    Zusätzliches Material: 13 Ill.
    Materialart: Digitale Medien
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  • 145
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. 51-56 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Models for the laminar sublayer of turbulent pipe flow are reviewed. The observations of the sublayer by Popovich and Hummel and the experimental fluctuation frequencies obtained by Shaw and Hanratty are used with the models to evaluate experimental heat and mass transfer data. The eddy diffusivity model and a parallel conductance model appear to be consistent with the experimental data.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 146
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. 81-85 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The effect of viscosity and diffusivity variations on concentration polarization during the ultrafiltration of protein solutions in two-dimensional stagnation flows is investigated by numerical integration of the equations of continuity and motion. It is found that these effects are surprisingly small and insensitive to the forms of concentration dependence postulated. The high Schmidt numbers and low permeation rates characteristic of these systems result in considerable simplification of the analysis and permit use of a modified Chilton-Colburn relation for predicting the onset of sludge formation at the membrane-solution interface. The predicted dependence on Schmidt number agrees with published experimental data for other boundary-layer flows and suggests the possibility of improved prediction of equipment performance.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
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  • 147
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. 246-248 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Zusätzliches Material: 1 Tab.
    Materialart: Digitale Medien
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  • 148
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. 255-256 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
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  • 149
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 150
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. 272-280 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The kinetics of simultaneous, noncatalytic solid-gas reaction systems has been analyzed in terms of the selectivity and effectiveness factor, based on the unreacted core shrinking model. The reaction systems discussed include the first-order independent, parallel, and consecutive reactions with the simultaneous influences of heat and mass transfer. The effects of various chemical and transport properties on the stability, selectivity, and effectiveness factor of the system are discussed. The pseudosteady state approximation is employed to reduce the mathematical difficulties.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
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  • 151
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. 291-294 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: An analysis is made of the Van der Waals forces of two different species when separated by a third continuous component. Results show that under certain circumstances, attractions as well as repulsions can exist between the two different species. The theory is applied to a fibrous bed coalescer to determine what type of material would best serve as a coalescence medium.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
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  • 152
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. 335-342 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The periodic process utilizes a rapid pressure swing cycle in an adsorbent bed to effect the separation of gas mixtures. During the first portion of a cycle the compressed gas mixture flows into the adsorbent-filled column. Next, while the feed gas is restrained, an exhaust orifice is opened at the feed end of the column providing depressurization. The product stream is enriched in the component exhibiting the lowest coefficient of adsorption.A mathematical model based upon the assumption of instantaneous equilibrium between the gas phase and the adsorbed gas was formulated and solved to simulate the periodic, adsorption process. The measured nitrogen content of the product gas stream was found to correlate with the ratio of the product gas rate to the feed gas rate.At 24°C. the calculated pressure response, feed gas flow rate, and product gas composition correspond favorably with related experimental measurements for all values of the feed gas pressure, cycling frequency, and product gas flow rate within the ranges investigated.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
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  • 153
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. 365-371 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The optimal control problem for multiple beds is formulated and a distributed maximum principle derived. Gradient methods are then used to synthesize the optimal control policies for some examples in three-bed isothermal and adiabatic reactors. Finally, examples are worked to illustrate the computational algorithm in adiabatic beds when optimal catalyst loading is to be determined, and when it is desired to distribute the feed in an optimal fashion between the beds. Reasonably good convergence was obtained in all the examples, so that the method appears quite feasible for determining optimal control policies in multiple reactors subject to catalyst decay.
    Zusätzliches Material: 10 Ill.
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  • 154
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. 383-390 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The nature of flow choking has been studied as steam-water mixtures are passed through a tube with ever increasing pressure gradient. Choked flow for two-phase, one-component mixtures has been characterized with a separated flow model as resulting from maximization of the ratio of gas to liquid velocities, or slip ratio. Slip ratios at choking were measured and found to increase from 1.2 to 5.0 at 30 lb./sq.in. exit plane pressure with decrease in quality from 0.95 to 0.02. Separated models predict either 9.3 or 28.4 with no quality dependence. The difference is attributed to liquid entrainment. Flow regimes were observed to vary from purely entrained to annular entrained to slug entrained as quality decreased. Normal shock waves were observed in the free jet at qualities above 0.25. Choking flow rates were predicted with an average error of less than 2% with a stagnation energy balance model using an empirically developed slip ratio relation corrected for entrainment.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
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  • 155
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. 257-257 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 156
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. 259-265 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Relationships have been developed for the calculation of second virial coefficients of polar fluids from the critical constants, acentric factor w, and fourth parameter x of the substance. Coefficients for the expansion of the reduced second virial coefficient in w and x are presented for 0.64 ≤TR ≤ 0.94. Comparisons with available experimental data indicate that good results are obtained by the method of this study for most polar fluids. The second virial coefficient for water is found to exhibit anomalous behavior. Procedures have also been established for extending the relationships for pure fluids to the second virial coefficient of mixtures containing nonpolar or polar components.
    Zusätzliches Material: 5 Ill.
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  • 157
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. 281-285 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The modification of the Blake-Kozeny equation for porous media flow using the power law has been shown to hold for molten polymers as well as for the previous cases for polymer solutions. The present work extended the correlation of friction factor with Reynolds number an additional three decades.It was also shown, however, that the modified Blake-Kozeny equation broke down when bed shear rates were in the range of excessive curvature on the polymer flow curves (shear stress-shear rate). In such cases it is suggested that the Newtonian Blake-Kozeny equation, together with apparent viscosity data, could be used to correlate such porous media flow of non-Newtonians.Appearance of viscoelastic effects at the critical Deborah number value of 0.05 predicted earlier were not found to hold. The data of the present investigation show that such a critical value must be at least 0.19 or even higher. This result helps to resolve partially the anomalous results obtained by previous investigators.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
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  • 158
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. 322-325 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Velocity profiles were calculated for transient fluid flow in the hydrodynamic entrance regions of a long narrow slit and of a long tube. The solutions were obtained by use of a linearized momentum equation. An estimate was also made of the manner in which the resistance to flow of the entrance region develops with time.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 159
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. 349-352 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Torque measurements were made in experiments carried out using a cylindrical Couette apparatus with the inner cylinder rotating and the outer one stationary. The fluid systems employed consisted of distilled water, 50% distilled-water glycerine solutions, and these with several concentrations of suspended polystyrene spheres (through 40 on 70 mesh). The parameters employed by Bjorklund and Kays were found to correlate the data successfully when suspension viscosities were used for the two-phase systems.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 160
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. 419-424 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: A three-stage procexsss of reduction of acid chromate (HCrO4-), with NaHSO3 followed by precipitation of Cr(III) with NaOH followed by flotation with an anionic surfactant, provides 97% removal of chromium from aqueous suspensions containing 48.3 mg./liter Cr (0.929 mM). The required dosage of surfactant (sodium laurylsulfate) is 0.093 mole SLS/mole Cr, compared to a dosage of 1.1 mole cationic surfactant/mole Cr, used to ion float soluble acid chromate. The precipitate flotation process is pH dependent: below pH 6.3, soluble chromium species become appreciable and the flotation results agree with calculated soluble chromium concentrations; above pH 9.7, the charge of the precipitate is reversed, as indicated by surface potential measurements. The optimum pH range for flotation is 7.0 to 8.8. The effect of initial surfactant concentration on the flotation efficiency is established. Small quantities of calcium enhance the flotation of Cr, while higher concentrations, 0.5 mM and greater, decrease flotation efficiency. For suspensions with a doubled chromium concentration (96.6 mg./liter), the optimum pH range for flotation is lowered and narrowed to 6.3 to 6.5, indicating modifications in particle surface characteristics validated by measurements of surface potential and surfactant adsorption. Eighty-seven percent flotation is achieved at a 0.093 mole/mole ratio.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
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  • 161
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. 2-2 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 162
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. 25-30 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: A numerical study was performed to investigate improvement in mass transfer rates obtainable by introduction of secondary convection into a proposed membrane blood oxygenator. The three-dimensional Navier-Stokes equations were solved numerically for the velocity field in channel and the results used in the numerical solution for the local Po2 in the oxygenator. The convective diffusion equation solved is nonlinear, in addition to being three-dimensional, because of the presence of red cell oxygen sinks.The convection introduced was generated by moving one wall of the blood flow channel laterally to the main flow. Decreases in blood side film resistance up to 5 × 104 were predicted. In the presence of moderate to strong convection, the limiting factor on oxygenation rate is imposed by the membrane situated between blood and gas phases. It appears that a considerable decrease in required blood priming volume would be possible if the method discussed here were implemented.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
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  • 163
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. 57-65 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The effects of aliphatic alcohols on mass transfer and drag coefficients of a carbon dioxide bubble were investigated in very dilute aqueous solutions. A high speed photography technique provided an almost continuous record of the bubble volume, shape, and oscillation, as related to the height of the bubble in the liquid and the time elapsed from the moment of its release. The results showed that the concentration, molecular size, and structure of the investigated alcohols have a pronounced effect on mass transfer as well as drag coefficients of the rising bubble. The significance of these effects with respect to idealized models of a highly circulating bubble and a solid sphere was considered, and a functional relationship was found to exist. This relationship may be applied to systems more complex than a single bubble.
    Zusätzliches Material: 21 Ill.
    Materialart: Digitale Medien
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  • 164
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. 75-81 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: A steady state experimental technique for measuring fluxes of the components and diffusivities in binary liquid systems has been developed. Steady state diffusion is established through a sintered glass diaphragm of ultrafine porosity with a known concentration difference across the diaphragm. The concentrations are maintained by a flow of solution on one side of the diaphragm and an infinite sink on the other side. The fluxes and diffusivities are calculated from the measured flows and compositions. A syringe pump capable of delivering extremely small flow rates with good reproducibility is used to pump the solution past the sintered glass diaphragm. The diffusion cell design permits an accurate control of pressure drop across the diaphragm so that fluxes can be measured both with and without pressure gradients. The diffusion cell was calibrated by using the hydrochloric acid-water system.Three binary systems, ethanol-benzene, aniline-benzene, and aniline-carbon tetrachloride were chosen for diffusion studies. Diffusivity-composition data for these systems at 25°C. were used to test the existing correlations for the concentration dependence of binary diffusivity. Of these, the empirical correlation of Vignes (11) represents the data satisfactorily. In addition, experimental molar diffusion flux ratio data for the above systems at 25°C. with no pressure gradients are reported and found to be essentially equal to the ratio of molar volumes of the components.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
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  • 165
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. 101-103 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Analyses of stretching of a viscoelastic liquid have been interpreted as showing that there is a maximum stretch rate to which the material can be subjected, and several physical phenomena have been explained on this basis. It is shown here theoretically and experimentally that the concept of a limiting stretch rate does not have general validity.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 166
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. 115-121 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The stability of a capillary liquid bridge of given volume between two small, solid, equal, separated spheres is investigated by formulating and treating a minimum energy problem in the calculus of variations and by experiment. A conjecture is made that in the case of two solutions one and only one is minimizing, and that the case of one solution represents the limiting stable bridge. This theory agrees accurately with our stability experiments. Furthermore, it is possible to predict the cohesive force. For the case of spheres in contact, the theory presented here is in agreement with some experimental work and also with the theory of Fisher and calculations of cohesive force based on Melrose and Wallick's solution to the bridge problem. For the case of separated spheres, the agreement with the only available experimental data is excellent except for close separations.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
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  • 167
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. 122-130 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Bubble size and distribution of bubble sizes were studied in an air fluidized bed, 11.5 in. in diam. and 3 ft. high, by taking motion pictures of the bubbles breaking the top surface of the bed and by determining the size of the bubbles from the film. The distribution of bubble volumes at a given bed height was expressed as a gamma distribution with parameters obtained from the observations. A statistical mechanical method proposed by Hulburt and Katz for studies in agglomeration of particles was used in the mathematical formulation of the problem. A proposed mechanism of bubble growth by coalescence in gas fluidized beds resulted in a one parameter model. Comparisons of the distributions predicted by the model to the experimentally obtained profiles yielded the parameter of the model.
    Zusätzliches Material: 16 Ill.
    Materialart: Digitale Medien
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  • 168
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. 148-153 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: A new approach to separation calculations has been developed which has many practical advantages. The equations of conservation of mass and energy and of equilibrium are grouped by stage and then linearized. The resulting set of equations has a block-tridiagonal structure which permits solution by a simple technique. Thus a new way to apply the Newton-Raphson technique to separation calculations is devised. The method has been tried on a number of problems chosen to exhibit characteristics which cause other solution technique to fail. Most problems are solved with ten iterations or less.
    Zusätzliches Material: 1 Ill.
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  • 169
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. 171-176 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Direct thermal parametric pumping separations of a NaCl-H2O-ion retardation resin system have been investigated. Experimental breakthrough curves and batch parapump runs were used to determine the lumped-parameter mass transfer coefficient λ and its dependence on velocity and temperature. Computer simulation of additional batch runs verified both the model and the STOP-GO algorithm used to solve it. Computer estimates of open-system behavior are presented.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
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  • 170
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. 191-198 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: A correlation based on conformal solution theory has been developed for the excess properties of the nitrogen-oxygen-argon systems. A better method for calculating the conformal parameters makes possible the simulataneous correlation of the three excess properties FE, HE, and VE. Each binary is characterized by a k12, c12 set which represents corrections to the geometric and arithmetic mean combination rules. These binary constants predict the ternary data. Also, the correlation based on data at one atm. (77° and 84°K.) predicts the FE data accurately up to the critical points (110° to 120°K.).
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
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  • 171
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    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. 215-219 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The problem treating an irreversible, first-order chemical reaction in an isothermal, tubular reactor operating under steady, non-Newtonian, laminar flow is studied. Numerical results for the eigenvalues, eigenfunctions, expansion coefficients and bulk concentration are reported for Ostwald-de Waele and Prandtl-Eyring fluids. Results show that chemical conversion in a tubular reactor may be significantly influenced by the non-Newtonian characteristics of a fluid.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 172
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. 252-254 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
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  • 173
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971) 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 174
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. 258-510 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
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  • 175
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. 285-288 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The following nucleation rate and growth rate relationships for the aqueous, continuous, cooling crystallization of potassium dichromate were determined from experimental crystal size distributions: J = 3.9 × 1010 (C - Ceq)0.9; r = 3.0 × 103 (C - Ceq)1.7. Since nucleation rate is of lower kinetic order than growth rate, higher levels of supersaturation will yield crystal distributions with a larger mean size. Therefore for this system, batch or plug-flow reactors are preferred to continuous-stirred tanks.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
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  • 176
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. 308-312 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: An experimental facility for vapor-liquid equilibrium measurements at high pressures (100 to 15,000 lb./sq. in. abs.) and ordinary temperatures (100° to 300°F.) on multicomponent mixtures is described. The vapor-liquid phase behavior of a six-component hydrocarbon mixture, which simulated a natural gas and a condensate, was studied with this apparatus. Measurements were made at 150° and 250°F. and pressures ranging from 100 lb./sq. in. abs. to the single-phase pressures for these systems and temperatures.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 177
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. 326-335 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: A method has been developed for applying classical minimization techniques to forms of algebraic performance indices for use in optimal adaptive control systems. Essentially, the derivative of a general objective function is constrained to be equal to the integrand of a desired integral performance index. This generates a set of linear algebraic equations, the solution of which results in an algebraic objective function which is explicit in the system parameters. Derivatives of this function can be taken with respect to the controllable parameters, set equal to zero, and solved for the settings which minimize the performance index over time. Alternatively, the function itself may be searched for its minimum on the controllable parameters.The method has been applied to a stirred tank chemical reactor with an exothermic first-order reaction in which heat removal was accomplished by cooling coils. The cooling water flow rate was controlled by a proportional-plus-integral controller and by a three-mode controller. The adaptive control system adjusted the controller settings periodically. The plant, which was third-order, was controlled to a second-order dynamic reference model. The responses to both initial offsets (start-up problem) and disturbances in system parameters were investigated. In all cases, the adaptive control system performance was markedly superior to that for the unadapted, ordinary feedback control system.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
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  • 178
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. 353-356 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Available generalized correlations of fugacity coefficients of nonpolar liquids are reexamined in their lower temperature ranges, and these correlations are extended to a reduced temperature of 0.35. Generalized functions are constructed from literature data on vapor pressures and liquid densities. Two sets of functions are presented with w and zc, respectively, as third parameter. The results fulfill a need for basic information in the engineering of cryogenic systems.The same vapor pressure data are correlated in a generalized form down to Tr = 0.35 to give a one-parameter family of reduced vapor pressures curves. The correlation is compared with data on simple fluids, normal fluids, polar substances, and quantum fluids.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
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  • 179
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. 379-383 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: An analysis is made of diffusion and chemical reaction in an isothermal multicomponent fluid. Transient gas-phase reaction in a one-dimensional nonflow system and steady state gas-phase or surface reaction in a tubular reactor are considered. The equations are linearized around some state away from equilibrium. Multicomponent and binary diffusivity expressions are used and a series of reactions of varying complexity is considered. The possibility of oscillations increases as the complexity of the reactions is increased. These oscillations occur with time in the nonflow system and with space-time in the tubular reactor, and it appears that any reacting mixture which oscillates in one of these two systems will also oscillate in the other.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 180
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. 402-409 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Pressure drag coefficients of spheres in a cubic packing of equal spheres have been determined at Reynolds numbers of 27,000, 10,000, 5,000 and 2,500, where NRe is based on superficial air velocity and a sphere diameter of 7 cm. Two cubic arrangements were used: in the regular arrangement, the mean flow was parallel to one of the principal axes, while in the skewed arrangement, the mean flow made equal angles with the three principal axes of the packing.The pressure drag coefficient of the central sphere has been measured for each of the 12 banks in the regular arrangement, and the effect of bed length has been determined for lengths varying between 1 and 12 banks. The pressure drag coefficient for the central sphere and the overall pressure drop in the skewed arrangement were found to be lower than for the regular arrangement at the same Reynolds number. From the distribution of local pressure measurements, the separation and reattachment points on the central sphere in each bank were determined, indicating that the boundary-layer behavior on a sphere in a packing is similar to that over a single sphere, when allowing for the effects of turbulence and of pressure gradient.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 181
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. 425-427 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Sufficiency conditions for equality constrained extrema are formulated in terms of a transformed set of coordinates by means of a generalized inverse of the constraint Jacobian matrix. This procedure produces a computationally simple and efficient method for testing sufficiency of a previously established stationary point. Computation of Lagrange multipliers is also facilitated by the method.
    Materialart: Digitale Medien
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  • 182
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. 446-454 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The kinetic patterns of sorption, desorption, and sorbate exchange have been studied for several C2-C5 hydrocarbons in synthetic zeolites of the mordenite, T and Y structures. The rate observations can best be represented by a model of sorption on interstitial sites in the solid, rather than by a model based on the analogy with macroporous sorbents. Two cases of interstitial diffusion have to be distinguished for this purpose. The number of vacant sites changes in time during the process of sorption, whereas it can remain constant if one sorbate is exchanged against another one. Rate measurements for both types of processes are reported and their interrelation is discussed.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
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  • 183
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. 470-475 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: A new method is presented for the determination of adsorption equilibria for pure components and mixtures both at high and low pressures. Isotherms for carbon dioxide, methane, ethane, propane, i-butane, n-butane, i-pentane, and n-pentane on activated carbon (Columbia grade NXC 8/10) and on silica gel (Mobil Sorbead H) at 75°, 125°, 200°, and 300°F. are given for pressures ranging from below atmospheric to 1,000 lb./sq. in. Also, adsorption equilibria data are presented for several multicomponent mixtures of the light hydrocarbon gases.The data collected were correlated with good accuracy by use of the two-layer kinetic model developed previously by Gonzalez.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
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  • 184
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. 504-505 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Zusätzliches Material: 3 Tab.
    Materialart: Digitale Medien
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  • 185
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. i 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Materialart: Digitale Medien
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  • 186
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. 762-762 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 187
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 188
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. 763-763 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 189
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. 513-519 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: This paper presents a nonequilibrium mathematical model of a vapor-liquid separator. The model is used as the focus of a computer simulation control study conducted to provide the foundation for applying recent multivariate control developments to distillation systems.Greenfield and Ward's structural analysis was found to provide reasonably good feedforward and decoupling control of pressure, liquid temperature, and liquid pressure. Because of implicit relationships between product composition variables and their manipulative inputs, structural analysis was inapplicable when these composition variables were among the controlled variables.A method is presented which provides feedforward and some decoupling control for linear multivariable systems despite the existence of implicit relationships between controlled variables and their manipulative inputs. It is seen however that genuinely decoupled servo action on isolated state variables requires control through derivatives and thus an expansion of state space.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
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  • 190
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. 519-528 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Mean velocity and turbulence measurements in the void spaces of a cubic packing of equal spheres have been made at Reynolds numbers of 27,000, 10,000, 5,000 and 2,500, where NRe is based on superficial air velocity and a sphere diameter of 7 cm. Two cubic arrangements were used: in the regular arrangement, the mean flow was parallel to one of the principal axes, while in the skewed arrangement, the mean flow made equal angles with the three principal axes of the packing.Transverse mean velocity and turbulence intensity profiles across the center line of a central pore have been measured behind every bank and behind the bed for the regular arrangement of ten banks of spheres. The power spectrum and probability distribution of the fluctuating velocity have also been determined.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
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  • 191
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. 529-535 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: A mathematical model of the heavy water production facility at the Savannah River Plant, an installation of the U.S. Atomic Energy Commission at Aiken, South Carolina, operated by E. I. du Pont de Nemours and Company, was developed because measured production rates, even when averaged over one-month periods, are inadequately precise for process control. With this model the instantaneous steady state production rate for any set of process conditions is calculated with precision. Therefore the model is used to establish process set points for achieving production goals, to study the effect of important process variables on these goals, and to evaluate proposed changes of equipment. In fact, with only minor changes in the computer program, several features of a newly designed heavy water plant are being evaluated.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
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  • 192
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. 536-541 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The processes of absorption and desorption with reversible reaction are compared theoretically for reactions of the type A ⇌ nB. With the same concentration difference between bulk and interface, it is found that in general, the rate of desorption is lower than that of absorption. Under certain conditions the difference may be as much as 35%.The analysis is based on the penetration theory. The numerical solution introduces a new transformation of the time and distance variables (based on the error function) which reduces the computing time required. An analytical examination of the penetration theory equations provides an explanation of the results of the numerical solution.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
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  • 193
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. 541-549 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The rates of hemoglobin saturation and carbon dioxide reduction in blood flowing in a curved channel membrane exchanger were studied theoretically by considering the fluid-limited process and the wall-limited process. The fluid-limited process was studied for laminar flows with and without secondary circulations. The relatively nontraumatic centrifugally induced circulations in the curved channel can reduce the required channel length to less than 1/500 that required for unperturbed flow. Such improvement, however, is practical only if very permeable membranes are available. If the PO2 = 715 mm. Hg and PCO2 = 0 mm. Hg at the walls, the fluid-limited analyses show oxygenation to be the slower process and the wall-limited analyses indicate CO2 removal to be the limiting process. If the best available silicone rubber membranes are used, the process will be fluid limited for the unperturbed flow and wall limited for the flow with secondary circulations.
    Zusätzliches Material: 14 Ill.
    Materialart: Digitale Medien
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  • 194
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. 550-553 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The relaxed steady state operation of a tubular fixed-bed catalytic reactor under control of the inlet composition is investigated. It is shown that the performance of such a reactor can be improved under certain conditions by periodically varying inlet concentrations rather than keeping these concentrations time invariant.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 195
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. 557-561 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: In this paper we consider the problem of the flow of a viscous incompressible fluid down an inclined wall. A solution is obtained by assuming that the free surface is a wave of low frequency. The solution is numerical and the results are compared with existing theories and available experimental results.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
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  • 196
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. 554-557 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: A theoretical model is derived which permits the analytical calculation of the friction factor-Reynolds number curves for non-Newtonian slurries flowing isothermally in smooth pipes. This model is based upon the Bingham plastic rheological equation of state.A change of mechanism in the transition phenomenon is observed to occur for NHe = 5 (105), where NHe is the familiar Hedstrom number. Below this value turbulence is suppressed relative to Newtonian flow, while above this value the transition is delayed but turbulence is enhanced relative to Newtonian flow.A set of theoretical design curves of friction factor versus Reynolds number covering laminar, transitional, and turbulent flows is calculated and presented for a range of NHe values from 103 to 109.
    Zusätzliches Material: 4 Ill.
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  • 197
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. 569-574 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Effective experimental and theoretical techniques for studying the heat transfer characteristics of a stationary evaporating meniscus formed on a flat plate immersed in a pool of liquid were developed. Integral heat transfer data were obtained for the four systems: 304 stainless steel-water, 6061 aluminum-water, 304 stainless steel-methanol, and 6061 aluminum-methanol. High rates of heat transfer were obtained in the triple interline region with a stable meniscus. Detailed descriptions of the heat flux and temperature field were obtained for the stainless steel-water and stainless steel-methanol systems. The effect of the evaporation coefficient on the heat flux distribution was evaluated. The heat transfer process in the interline region proved to be more efficient than a simple conduction process in an evaporating liquid meniscus.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
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  • 198
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. 585-589 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: A generalized correlation is presented for the backmix ratio in multistage agitated contactors. The backmix ratio is shown to be a function of the ratio of impeller tip speed to superficial flow velocity, and of the column configuration and impeller design. For single-phase flow and for the continuous phase in two-phase flow, the following expression is recommended: \documentclass{article}\pagestyle{empty}\begin{document}$$\alpha = 0.0098\left[ {\varepsilon \frac{{ND}}{u}\left( {\frac{{D^2 a}}{{THA}}} \right)^{1/2} } \right]^{1.2}$$\end{document}
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 199
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. 562-569 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: An analytical technique based on the method of least squares has been developed to fit experimental second virial coefficients to the functional form derived from the Lennard-Jones (6-12) potential. Both the functional form and the normal equations of the least squares fit are rigorously derived. Because of the implicit, nonlinear dependence upon one of the adjustable parameters, a computer solution of the normal equations is required. Second virial coefficient data for a large number (60) of materials, including hydrocarbons, halides, alcohols, and cyclic compounds, have been extracted from published sources, carefully evaluated for consistency, and fitted to the Lennard-Jones potential function.Force constants for these materials as determined from fitting the data in this uniform manner have been found to be related to structural parameters. The final correlation, with the potential well-depth related to critical temperature and the collision diameter calculated from a set of group contributions with appropriate corrections for polarity and/or association, produces average deviations between computed and experimental second virial coefficients of 10 to 15% or 100 cc./g.-mole, whichever is greater. In many cases the agreement is much better.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 200
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. 575-584 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: A study was made of the atomizing characteristics of convergent-type pneumatic nozzles. Drop-size correlations were obtained for the following ranges: drop size, 6 to 350 μ, mass median diameter; mass flow ratio, 0.06 to 40; relative velocity, 250 ft./sec. to sonic velocity; and viscosity. 1 to 50 cp. The technique employed was to spray cool a molten wax, and melts of wax-polyethylene mixtures. The most important operating variables in pneumatic atomization are the dynamic force of the atomizing gas, and the mass flow ratio of air to liquid. The cumulative volume drop-size distribution of spray from a pneumatic nozzle was fitted by a modified logistic equation. Empirical correlations developed in the study can be used to design nozzles or to predict drop size for sprays produced by the types of nozzles studied. In particular, this study provides new experimental data on the performance of pneumatic atomizers in producing relatively large drops.
    Zusätzliches Material: 16 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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