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  • 2020-2023
  • 1965-1969  (272)
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  • 1968  (272)
  • Chemical Engineering  (257)
  • Electron microscopy  (15)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Anatomy and embryology 127 (1968), S. 154-164 
    ISSN: 1432-0568
    Keywords: Collagen ; Connective tissue ; Electron microscopy ; Polarization microscopy ; Tendons
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The correlation of the mechanical properties and the morphological behaviour of collagenous tissue during strain was investigated. Relaxed and strained tendons were examined by incidental and transmitted polarized light microscopy and electron microscopy. It was concluded that the wavy pattern seen at the seminicroscopic level of the collagen fibers vanished at relatively low loads. The direction of birefringence in transmitted light microscopy varied in the relaxed preparations but became even in the strained. The electron microscopy showed that the fibrils had the same periodicity as calculated from X-ray diffraction patterns of moist collagen, i.e. 680 Å, and that straining increased the period lengths of some fibrils. The correlation of these findings to a mechanical analogy of the tissue was discussed.
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  • 2
    ISSN: 1432-0533
    Keywords: Electron microscopy ; Skeletal muscle ; Ring fibers (Ringbinden) ; Sarcoplasmic masses ; Sarcomere fragmentation ; Myofilaments
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Résumé Dans diverses conditions habituellement pathologiques, la fibre musculaire peut comporter une zone périphérique nettement individualisée et contenant des formations filamentaires dont la disposition spatiale est anormale. Les auteurs analysent les aspects ultrastructuraux de trois types de telles formations filamentaires périphériques: 1. lesfibrilles annulaires, bien visibles en microscopie optique; la microscopie électronique permet d'établir leur structure myofibrillaire normale, la fréquence des aspects complexes d'entretissage entre ces myofibrilles et les myofibrilles de disposition longitudinale; 2. lesmasses latérales dites “sarcoplasmiques” en microscopie optique, dont l'analyse en microscopie électronique permet d'établir la richesse fréquente en formations myofilamentaires disposées de façon anarchique; 3. lesempilements de fragments de sarcomère selon les différents plans de l'espace, qui ne peuvent être mis en évidence en microscopie optique, et n'apparaissent clairement qu'en microscopie électronique. L'étude ultrastructurale permet de récuser le caractère artificiel de ces différents aspects, souvent envisagé en microscopie optique, d'insister sur le caractère topographique limité le plus souvent à la périphérie de la fibre de telles altérations, et sur la fréquence de l'association de ces différentes anomalies entre elles. Cette étude apporte en outre des arguments en faveur de la nature dégénérative de ces aspects. Ces anomalies ne sont spécifiques d'aucune affection musculaire particulière, mais les auteurs les ont rencontrées cependant avec un maximum de fréquence dans les dystrophies musculaires progressives.
    Notes: Summary In various—usually pathologic—conditions the muscle fibre may show a distinct peripheral zone containing abnormally arranged filamentous formations. The authors have analysed the ultrastructural aspects of three types of such peripheral filamentous formations: 1.ring-shaped fibrils clearly visible under the light microscope; in these cases the electron microscope reveals their normal myofibrillar structure as well as the high incidence of complex formations resulting from the intertwining of such myofibrils and longitudinally disposed ones; 2. so-called“sarcoplasmic” lateral masses under light microscopy; in these cases the electron microscope shows a wealth of irregularly disposed myofilamentous formations; and 3.accumulations of sarcomere fragments at different spatial levels, which may be distinguished only under the electron microscope but not by light microscopy. The ultrastructural study permits the authors to disprove the artificial character of these different aspects—an assumption frequently made on the basis of light-microscopic findings—, to insist on the fact that such alterations are mostly limited topographically to the periphery of the fibre, and to stress that these different anomalies are often associated with one another. The study has furthermore furnished considerable evidence in favour of the degenerative nature of the forms under consideration. The anomalies in question are not specific to any one muscular affection; however they have been found most frequently in progressive muscular dystrophy.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 10 (1968), S. 336-346 
    ISSN: 1432-0533
    Keywords: Electron microscopy ; Rat brain, new born ; Porencephalic cyst ; Brain injury ; Glial reactions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Stichverletzung des Gehirns neugeborener Ratten erzeugte regelmäßig eine Defekthöhle, deren Begrenzung zuerst aus einer Schicht fibrillärer Astrocyten mit vielen dünnen Cytoplasmafortsätzen bestand. Während der 2. und 3. Woche wurde die Astrocytenschicht lockerer und durch eine Basalmembran abgegrenzt, die gewöhnlich in Verbindung mit einer darüberliegenden Schicht von Pia-ähnlichen Zellen stand, Erst hernach ähnelte die Feinstruktur der Defektwand jener der Heldschen “Membrana gliae accessoria” für die differenzierte Struktur vorbehalten bleiben und nicht zur Bezeichung der frühen Astrocytenbegrenzung verwendet werden sollte. Keine dichte Glia-oder Bindegewebsnarbe, wie im Erwachsenengehirn üblich, wurde gefunden. Die Makrophagen verschwinden vor der 3. Woche, anstelle monatelang wie beim Erwachsenen zu verweilen. Das Vorhandensein oder Fehlen von Narbenbildung und Makrophagen dürfte nur das Alter, in dem die Verletzung erfolgte, widerspiegeln und daher für die Unterscheidung zwischen Mißbildungs-und Verletzungsdefekten unverläßlich sein.
    Notes: Summary Needle injury of the newborn rat brain resulted regularly in cavity formation, the lining of which at first consisted of a layer of fibrous astrocytes with many thin cytoplasmic projections. Between the second and third weeks the astrocytic surface became smoother and was lined by a basement membrane, usually in association with an overlying layer of pia-like cells. Only after this time did the fine structure of the cavity wall resemble that of Held's membrana gliae limitans superficialis. It is, therefore, suggested that Spatz's “membrana gliae limitans accessoria” be reserved for this differentiated structure and not used to identify the earlier astrocytic lining. No dense glial or connective tissue scarring, as usually seen in the adult brain, was found. Macrophages disappear before the third week, rather than persisting for months, as in the adult. The presence or absence of scar formation and macrophages may only reflect the age at which the injury occurred and may, therefore, be unreliable in distinguishing between cavities due to malformation and to injury.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 10 (1968), S. 17-25 
    ISSN: 1432-0533
    Keywords: Myelinated CNS axons ; Axoplasm ; Tubular structures ; Axonal reactive changes ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Eine honigwabenartige tubuläre Anordnung wurde in stark myelinisierten Axonen gefunden. Sie wurde im Kleinhirn einer offenbar gesunden Ratte und eines Schimpansen mit Kuru-ähnlichen Symptomen beobachtet. Sie fand sich ferner in der Großhirnrnde einer Maus mit einem intracerebralen Tumorimplantat. Eine verbindliche Ursache konnte nicht aufgedeckt werden. Es wird jedoch angenommen, daß diese Struktur eine spezifische axonale Reaktion auf eine mögliche Vielfalt von noch unbekannten Bedingungen entspricht.
    Notes: Summary A honeycomb-like tubular array was observed in heavily myelinated axons. It was observed in the cerebellum of an apparently normal rat and a chimpanzee with “Kurulike” symptoms. It was also found in the cerebral cortex of a mouse that had had a intracerebral tumor implant. A common underlying etiology could not be found. It is suggested, however, that this structure represents a specific axonal response to perhaps a variety of as yet unknown conditions.
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 10 (1968), S. 132-142 
    ISSN: 1432-0533
    Keywords: Myoclonus body disease ; Lafora bodies ; Electron microscopy ; Corpora amylacea ; Unverricht-Lundborg disease
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Résumé Les auteurs analysent l'ultra-structure des corps de Lafora à propos d'une biopsie cérébrale pratiquée dans une maladie d'Unverricht-Lundborg caractéristique. La surcharge observée dans les périkaryons neuronaux et dans les prolongements dendroaxonaux, au niveau des synapses, comporte des structures filamenteuses hélicoïdales de 75 Å d'épaisseur, correspondant à des macro-molécules protéiques complexes, des corpuscules denses de 150 à 300 Å et une matrice finement granuleuse. Les corps de Lafora, dépourvus de membrane propre, correspondent à une sécrétion anormale ou à une transformation d'organites cellulaires. Des relations de continuité existent entre les filaments et les ribosomes ergastoplasmiques. Les auteurs soulignent les relations unissant corps de Lafora et corps amylacés. Ils discutent leur morphologie et la comparent à celle de plusieurs structures pathologiques connues d'aspect fibrillaire.
    Notes: Summary The authors analyse the Lafora bodies' ultra-structure about a cerebral biopsy in a typic case of Unverricht-Lundborg disease. This obvious storage is noticed in the nerve cells perikarya, dendro-axonal processes and synapses; it appears to be compound of helicoïdal, filamentous, 75 Å wide profiles corresponding to complex proteic macro-molecules, 150–300 Å wide densities and slightly granulous matrix. The Lafora bodies without any limiting membran correspond to a pathologic neuro-secretion or to changes of cytoplasmic organites. Some continuity is seen between filaments and ribosomes. The authors emphazise the relations connecting Lafora bodies and corpora amylacea. Their morphology is discussed and compared with that of several pathologic fibrillar structures.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 10 (1968), S. 263-272 
    ISSN: 1432-0533
    Keywords: Hypertensive encephalopathy ; Ischemic-anoxic encephalopathy ; Edema anoxic ; Electron microscopy ; Astrocytic swelling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Es wurden elektronenmikroskopische Untersuchungen am Gehirn von Katzen bei akuter Hypertonie, die durch wechselnde Kompression der absteigenden Aorta erzeugt wurde, ausgeführt. Die ultrastrukturellen Veränderungen umfaßten Schwellung der Astrocytenausläufer, Erweiterung des endoplasmatischen Reticulums, und geringe Erweiterung des Extracellulärraumes des Gehirnmarks. Manchmal wurde auch Schwellung der Mitochondrien mit Zerstörung der Cristae beobachtet. Der Extracellulärraum der Gehirnrinde zeigte keine Erweiterung. Die Veränderungen in der Ultrastruktur des Zentralnervensystems werden im Hinblick auf die Pathogenese der hypertonischen Encephalopathie diskutiert.
    Notes: Summary Electron microscopic examinations were carried out in the brains of cats with acute arterial hypertension produced by intermittent compression of the descending aorta. The ultrastructural changes included swelling of the astrocytic processes, dilatation of the endoplasmic reticulum, and slight enlargement of the extracellular space of the white matter. Swelling of the mitochondria with disruption of the cristae was sometimes observed. The extracellular space of the gray matter showed no expansion. The changes in the ultrastructure of the central nervous system in hypertensive and ischemic encephalopathy were found to be very similar. This finding is discussed with special regard to the pathogenesis of acute hypertensive encephalopathy.
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 10 (1968), S. 308-323 
    ISSN: 1432-0533
    Keywords: Experimental brain tumors ; Virus with brain tumors ; Electron microscopy ; Histochemistry ; Hydrocarbon (crystalls), oncogenic
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Krebserzeugende Kohlenwasserstoffe wurden in Gehirn und Muskel von C3H Mäusen implantiert. Dabei konnten virusähnliche, cylindrisch geformte Partikel in den präcarcinomatösen Läsionen nachgewiesen werden. Die filamentartigen Stäbchen wurden nur im Cytoplasma von solchen Zellen beobachtet, die phagocytiertes Carcinogen enthielten. Die meisten Zellen, in denen diese Viruspartikel nachzuweisen waren, wurden als Makrophagen angesehen und es wird angenommen, daß sie mesenchymaler Herkunft sind. Der genaue Mechanismus, durch den die krebserzeugende Wirkung der Kohlenwasserstoffe zur Bildung von Viruspartikel führt, ist nicht klar, aber offensichtlich ist das endoplasmatische Reticulum beteiligt. Viele Partikel konnten innerhalb der Cisternen beobachtet werden; dabei wurde ihre äußere Hülle von der Membran des endoplasmatischen Reticulums gebildet. Gelegentlich wurden die Viruspartikel auch zwischen den zwei Membranen der Kernhülle beobachtet. Die Bedeutung dieser Partikel in Beziehung zu den Tumoren ist unbestimmt. Die Möglichkeit besteht, daß sie eine unreife oder unvollendete Form darstellen und daß zusätzliche Faktoren erforderlich sind, um ihre krebserzeugende Wirkung hervorzubringen.
    Notes: Summary Carcinogenic hydrocarbons were implanted into brain and muscle of C3H mice. Virus-like particles of cylindrical form were demonstrated in the precancerous lesions. These filamentous rods were observed only within the cytoplasm of those cells which contained phagocytosed carcinogen. The majority of reactive cells containing the virus-like particles were identified as macrophages, and are thought to be mesenchymal in origin. The precise mechanism by which the carcinogenic effect results in the formation of virus-like particles is not clear, but evidently involves the endoplasmic reticulum. Many of the particles were found within the cisternae, and their outer shells were derived from the membranous component of the endoplasmic reticulum. Occasionally, they were seen between the two membranes of the nuclear envelope. The significance of these particles in relationship to tumors is not certain. The possibility exists that they represent immature or incomplete forms and that additional factors may be necessary to prove them oncogenic.
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 10 (1968), S. 324-335 
    ISSN: 1432-0533
    Keywords: Electron microscopy ; Rat brain, new born ; Brain injury ; Brain edema ; Extracellular space
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Die Reaktion des Gehirns neugeborener Ratten auf Stichverletzung wurde elektronenmikroskopisch untersucht. Die wenigen im Neugeborenenhirn vorhandenen protoplasmatischen Astrocyten erschienen an der Reaktion unbeteiligt. Hingegen erwies sich der Extracellularraum durch Anhäufung von Ödemflüssigkeit erweitert. Die Mikrogliazellen reagieren bemerkenswert schnell; viele, ganze Zellen sowie Myelinfiguren und Fetttröpfchen enthaltende Makrophagen werden schon 24 Stunden nach der Verletzung gefunden. Eine dichte Glia- oder Bindegewebsnarbe bildet sich nicht. Diese Reaktionen sind von denen für das reife Hirngwebe charakteristischen durchaus verschieden; mögliche Erklärungen für diese Unterschiede werden erörtert.
    Notes: Summary The reaction of the newborn rat brain following needle injury has been studied electron microscopically. Very few protoplasmic astrocytes are present in the newborn brain, and they do not appear to participate in the reaction. Instead, the extracellular space appears to be widened by an accumulation of oedema fluid. The microglial cells react remarkably rapidly; many macrophages containing whole cells as well as myelin figures and lipid droplets are found within 24 hours after the injury. At no time does a dense glial or connective tissue scar form. These reactions are quite different from those characteristic of mature brain tissue, and possible explanations for these differences are discussed.
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  • 9
    ISSN: 1432-0533
    Keywords: Hypocupremia, experimental ; Vascular pathology ; Basal brain arteries ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Kaninchen wurden in utero und post partum unter Entzug von Kupfer aus der Nahrung aufgezogen (die Nahrung enthielt nur 0,60 p.p.m. Kupfer). Eine Gruppe von Kontrolltieren wurde ebenfalls untersucht. Bei der post partum-Gruppe der Kaninchen dauerten die Versuche 2 Monate. Am Ende der 7. Woche wurden petechiale Blutungen in den Ohren beobachtet. Angiographisch wurden Gefäße des Kopfes und Nackens untersucht. Einige Dilatationen und Ungleichheiten wurden beobachtet. Bei zwei Tieren wurden Herzrisse festgestellt. Innerhalb von 2 Monaten wurden alle Tiere getötet und seziert. Es wurden Darmblutungen festgestellt. In der linken Niere einer der kupferarmen Kaninchen wurde eine cystenartige Bildung gefunden. Dieser Befund mag ein zufälliger gewesen sein. Das Herz, Cervicalgefäße und basale Hirngefäße wurden licht- und elektronenmikroskopisch untersucht. Anhäufungen von Fibroblasten, dissektive Blutungen und Defekte oder Brüche in Muskel- und elastischen Geweben wurden beobachtet. An den fibrösen Stellen wurde eine Anhäufung von neutral-rotem Material gefunden. Die Folgen des Entzugs von Kupfer aus der Nahrung waren somit Veränderungen des Herzens, muskulärer und elastischer Schichten der Cervicalgefäße und basalen Hirngefäße.
    Notes: Summary Rabbits were reared in utero and post partum under hypocupremic conditions (the diet containing only 0.60 p.p.m. copper). A control series was investigated as well. For the post partum series of rabbits the experiments lasted 2 months. At the end of the 7 th week petechial hemorrhages were observed in the ears. Angiography was carried out and cervical and head vessels were studied. Some vessel dilatations and unevennesses were observed. One animal died of heart rupture and another collapsed as a consequence of intramural bleeding in the ventricular wall. Within about two months all the animals were killed and autopsied. Intestinal bleedings were observed. A cystlike structure was found in a kidney of one hypocupremic rabbit. This finding may have been coincidental. The hearts and cervical and basal cerebral vessels were investigated by light and electron microscopy. Fibroblast accumulation, dissecting hemorrhages and defects or breaks in muscular and elastic tissue were observed. At the sites of fibrosis, accumulation of a neutral red-positive material was found. At the ultrastructural level lipids could be identified. Deprivation of dietary copper thus resulted in changes of the heart and muscularis and elastica layers of cervical and basal cerebral vessels of rabbits.
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 10 (1968), S. 218-241 
    ISSN: 1432-0533
    Keywords: Myotonic dystrophy ; Sarcoplasmic masses ; Striated annulets (Ringbinden) ; Muscle fiber ; Electron microscopy ; Phase microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Das Biopsiematerial von drei Patienten mit unterschiedlichen klinischen und pathologischen Stadien der myotonischen Dystrophie wurde phasenkontrast-und elektronenmikroskopisch untersucht. Beim 1. und 2. Fall waren “sarkoplasmatische Massen” und “Ringbinden” besonders zahlreich, während sie beim 3. Fall mit klinisch erheblich fortgeschrittener Muskelatrophie nur ausnahmsweise vorkamen. Elektronenmikroskopisch erschienen fast alle Elemente der Muskelfasern, zumindest an einigen Stellen, von dem atrophischen oder dystrophischen Prozeß betroffen: Myofilamente, Z-Streifen, Triaden, Kerne, Mitochondrien und Sarkolemm. Außerdem fanden sich cytoplasmatische Cysten, multilamellierte Körperchen, zahlreiche Lipofuscingranula und verschiedene andere abnorme Strukturen. Besonders kennzeichnend für die Erkrankung waren die “sarkoplasmatischen Massen”, die mit variablen Mengen von fehlorientierten Myofilamenten, aber auch von anderen Komponenten der Muskelzelle ausgefüllt waren. Die Ringbinden wurden von fehlorientierten Myofibrillen gebildet, indem sie meist kreisförmig die im Zentrum normal ausgerichteten Myofibrillen umschlossen. Einzelne Veränderungen, die bisher weder bei der myotonischen Dystrophie noch in irgendeiner anderen Muskelkrankheit nachgewiesen worden sind, konnten in leicht dystrophischen wie auch in hochgradig atrophischen Fasern nachgewiesen und identifiziert werden: Große homogene Lacunen, die sich vom sarkoplasmatischen Reticulum herleiten und eigenartige geometrische Anordnungen der terminalen Cisternen. Der Ursprung bestimmter anderer Strukturen blieb unklar. In unserem Material fanden sich keine segmentalen Nekrosen, so daß sich die Relation des dystrophischen Prozesses zur Zenkerschen Degeneration und zur Atrophie, den nach histologischen Untersuchungen wesentlichsten Befunden bei der Steinertschen Erkrankung, nicht eindeutig bestimmen ließ.
    Notes: Summary Biopsies from three patients with different clinical and pathological stages of myotonic dystrophy were studied by phase and electron microscopy. Large sarcoplasmic masses and spiral annulets were prominent in Cases 1 and 2 while in Case 3, featured clinically by atrophic weakness, they were infrequent. In the latter the residual fibers were either large and dystrophic or small and atrophic. Electron microscopically, nearly all components of the muscle cell, in places, were involved in the dystrophic or atrophic process, such as myofilaments, Z discs, triads, nucleic, mitochondria, and the sarcolemma. In addition, cytoplasmic cysts, multilammellated bodies, and lipofuscin granules were observed. The most characteristic feature of the disease were sarcoplasmic masses, filled with varying amounts of disoriented myofilaments and other sarcoplasmic components. Disoriented myofibrils often encircled the remaining core of normal myofibrils, thus forming the striated annulets (Ringbinden). Several other abnormalities, not previously reported in myotonic dystrophy or any other myopathy, were identified in slightly dystrophic as well as in severaly atrophic fibers. These were large, homogenous lacunes derived from the sarcoplasmic reticulum and peculiar geometric arrangements of terminal cisternae. The origin of some other structures remains obscure. The relation of the dystrophic process to segmental degeneration and atrophy, the principal histologic findings in Steinert's disease, is unsettled since segmental necrosis was not observed in our samples for phase and electron microscopy.
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  • 11
    ISSN: 1432-0533
    Keywords: Nuclear inclusion body ; Herpes-virus-infection ; Immunology ; Electron microscopy ; Nuclear metabolism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Es werden die pathologischen Befunde bei einem 28 jährigen, schwachsinnigen Patienten beschrieben, der seit früher Kindheit progressive Spastizität und Ataxie zeigte. In Gehirn und allen anderen Organen wurden weitverbreitet eosinophile, intranucleäre Einschlußkörperchen, zugleich mit größeren, intensiver gefärbten, globulären Ablagerungen, gefunden. Corpus striatum, innere Kapsel, Pallidum und Thalamus waren besonders schwer betroffen. Die globulären Ablagerungen hatten sich wahrscheinlich aus vergrößerten, intranucleären Einschlußkörperchen entwickelt. Färberisch und histochemisch gaben beide Strukturen eine positive Reaktion für Protein. Entzündliche Reaktionen waren nicht vorhanden. Die Elektronmikroskopie zeigte, daß die intranucleären Einschlußkörperchen und die globulären Ablagerungen aus homogenem, feinkörnigem Material bestanden. Im Innern einer solchen Ablagerung in der inneren Kapsel wurden virusähnliche Partikel gesehen, die entweder unregelmäßig verteilt oder kristallartig angeordnet waren. Die Partikel sahen denen der Herpesvirusgruppe ähnlich. Es wird die Möglichkeit diskutiert, ob diese Veränderungen den Endzustand einer alten, generalisierten Herpesvirusinfektion darstellen, die entweder in früher Kindheit, zur Zeit der Geburt oder im Uterus stattgefunden hatte. Um den einzigartigen morphologischen Befund zu erklären, wird die Hypothese aufgestellt, daß entweder eine primäre immunologische Unzulänglichkeit vorlag oder daß eine Virusinfektion stattfand, bevor eine immunologische Kompetenz erworben war. Es wird kurz auf die zweite Möglichkeit hingewiesen, daß der Prozeß eine primäre, das Kernprotein beeinflussende Stoffwechselkrankheit darstellen könnte.
    Notes: Summary The pathologic findings are described in a mentally-retarded 28-year old man with progressive spasticity and ataxia since childhood. They consisted in the widespread presence, throughout the brain and visceral organs, of eosinophilic intranuclear inclusions, with the association of larger, more intensely staining globular bodies. The corpora striata, internal capsule, pallida and thalami were the most severely affected. The globular bodies seemed to be derived from the enlargement of the intranuclear inclusions: both gave the tinctorial and histochemical reactions for protein. There was no evidence of inflammation. Electron microscopy showed that the intranuclear inclusions and the globular bodies were composed of homogeneous finely granular material. In one such mass, in the internal capsule, virus-like particles, both randomly distributed and arranged in crystalline arrays, were seen. The particles resembled those of the herpesvirus group. The possibility is discussed that these alterations may present the residuum of an old generalized herpesvirus infection which could have been incurred in early life, at birth, or in utero. The hypothesis of a primary immunologic deficiency, or of a viral infection having occurred before the acquisition of immunologic competence, is advanced in order to account for the unique morphologic features. The alternative suggestion of a primary metabolic disorder affecting nuclear protein is briefly considered.
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  • 12
    ISSN: 1432-0533
    Keywords: Inclusion body, intranuclear ; Leucoencephalitis, subacute sclerotizing ; Electron microscopy ; Microtubuli (ultrastructural) ; Myxovirus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Ein klinisch-biologisch völlig typischer Fall von SSLE wurde enzymhistochemisch und elektronenoptisch untersucht. Enzymhistochemisch erwiesen sich die Läsionen als unspezifisch. Die nachgewiesenen Zunahme der oxydativen Enzyme ist identisch mit jener, die man bei allen reaktiven Makro- und Mikrogliosen beobachtet. Elektronenoptisch fanden sich keine intranucleären Einschlüsse aus Mikrotubuli von 170 bis 230 Å Durchmesser, deren Morphologie an gewisse Myxoviren erinnert. Andererseits bot dieser Fall auch lichtoptisch keine sicher nachweisbaren Kerneinschlüsse vom Typ Cowdry A, die bei SSLE nicht obligat sind. Die von einem Verfasser erstmals beobachteten mikrotubulären Einschlüsse erscheinen als das am meisten spezifische ultrastrukturelle Element der SSLE. Hingegen fanden sich bei der vorliegenden Beobachtung intracytoplasmatische Partikeln von virusähnlichem Aussehen, die vonGonatas bei SSLE und von den Verfassern bei entzündlicher diffuser Sklerose Typ Schilder beschrieben wurden. Gegenwärtig ergibt sich der Eindruck, daß diese Partikeln nicht spezifisch sind und ihre Deutung als virale Elemente größter Vorsicht bedarf. Es könnte sich um Sekretgranula in der Glia unter bestimmten pathologischen Bedingungen handeln, oder aber um phagocytierte Partikeln, die beispielsweise aus dem Myelin stammen.
    Notes: Summary Enzyme histochemical as well as electron microscopic studies were made in a typical case of SSLE. From the enzyme histochemical point of view the lesions were not specific, and the observed increase of oxydative enzymes is identical with that found in every reactive macro- and microgliosis. No intranuclear inclusions of microtubuli with a diameter of 170–230 Å resembling certain mixoviruses could be demonstrated by electron microscopy. By light microscopy, nuclear inclusions of the Cowdry type could not be demonstrated neither; however, they are not always found in SSLE. The microtubuli inclusions, observed for the first time by one of us, seem to be the most specific element in SSLE. On the other hand, the intracytoplasmatical particles with a virus-like aspect which have been described byGonatas in SSLE and by ourselves in periaxial diffuse encephalitis of the Schilder type were also found in the present case. Our impression is that these particles are nonspecific and great caution has to take place in classifying them as viral elements. They might be secretory granules arising in the glia in certain pathological conditions, or perhaps phagocyted particles, possibly stemming from myelin.
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  • 13
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    Acta neuropathologica 10 (1968), S. 279-294 
    ISSN: 1432-0533
    Keywords: Neurofibromas ; von Recklinghausen's disease ; Neurinomas (or schwannomas) ; Electron microscopy ; Peripheral nervous tumors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Résumé L'examen en microscopie optique et électronique de 6 neurofibromes prélevés chirurgicalement chez des patients atteints de maladie de Recklinghausen autorise un certain nombre de conclusions: l'ultrastructure des neurofibromes est faite de 2 types de cellules (cellules de Schwann et fibroblastes) dispersées au sein d'un espace extra-cellulaire contenant de nombreuses fibres de collagène. Des axones myélinisés et amyéliniques sont présents; l'aspect ultrastructural de 3 neurinomes de l'acoustique a été comparé à celui des neurofibromes et apparaît comme différent. Les neurinomes sont faits d'un seul type cellulaire (très probablement cellule de Schwann), le collagène y est beaucoup moins abondant, les axones absents. Quelques déductions pathogéniques et nosologiques sont proposées.
    Notes: Summary Six neurofibromas from patients with von Recklinghausen's disease have been examined by light and electron microscopy: 2 types of cells have been found (Schwann cells and fibroblasts) scattered in extracellular spaces rich in collagen fibers. Myelinated and nonmyelinated axons were observed. These data have been compared with other ones collected from 3 acoustic neurinomas. These latter contained only one cellular type (very likely to be Schwann cell), much less collagen and no axon at all. A pathogenic and nosologic discussion is given.
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  • 14
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    Experimental brain research 6 (1968), S. 89-99 
    ISSN: 1432-1106
    Keywords: Substantia gelatinosa ; Dorsal root fibers ; Light microscopy ; Electron microscopy ; Operated rats
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The terminal degeneration in the substantia gelatinosa of the rat was studied with the Fink-Heimer silver technique following dorsal root section. Providing the survival time of the animal was in the range of 1–4 days, a massive degeneration was seen in lamina I, II and III of Rexed. The light microscope findings were corroborated by electronmicroscopic observations of degenerating boutons. Spinal cord material examined with silver methods one week after dorsal root section showed few signs of degeneration in the substantia gelatinosa. Although a significant dorsal root distribution to the substantia gelatinosa was found also in the cat, the terminal degeneration in lamina II showed considerable regional variations in this species.
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  • 15
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    Clinical and experimental medicine 148 (1968), S. 255-274 
    ISSN: 1591-9528
    Keywords: Adipose tissue ; Fat cells ; Isolated fat cells ; Electron microscopy ; Ultrastructure ; Tissu adipeux ; Cellules adipeuses isolées ; Microscopie électronique ; Ultrastructure ; Fixation de tissus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Résumé Au cours de ces dernières années, la recherche biochimique au niveau du tissu adipeux a pris un très grand développement. La technique d'isolement des cellules adipeuses a beaucoup contribué à accroître la connaissance de leur métabolisme, rendant plus nécessaire encore l'étude des corrélations existant entre les données biochimiques et l'aspect ultrastructural. Ce travail porte sur la préparation de ce matériel pour l'observation au microscope électronique. Les cellules adipeuses sont des «gouttes» lipidiques recouvertes d'une fine couche de cytoplasme. La fragilité qui en résulte nécessite une préparation particulière: 1. les cellules doivent être maniées avec précaution tout au long de la préparation; 2. il faut fixer très peu de cellules à la fois; 3. cette fixation requiert une concentration élevée d'osmium, sans quoi les lipides de la cellule restent partiellement solubles dans les solvants employés pour la déshydratation. Il faut admettre que l'osmium modifie les propriétés de solubilité des triglycérides, probablement de par sa fixation au niveau des doubles liaisons, ou en facilitant une liaison en chaîne unissant les triglycérides entre eux par l'intermédiaire des doubles liaisons de leurs acides gras; 4. l'enrobage peut être fait au Vestopal ou à l'Epon, ce dernier étant techniquement plus maniable. Isolées, les cellules adipeuses sont semblables aux cellules fixéesin situ. Les cellules adipeuses présentent une particularité: la gouttelette lipidique est isolée du cytoplasme par une membrane elle-même doublée du côté cytoplasmique par des saccules du reticulum endoplasmique lisse disposés parallèlement à elle.
    Notes: Summary During these past years, an increasing attention has been paid to the biochemical aspects of metabolic regulation in adipose tissue. An important advance has been that of the availability of a technique for the isolation of adipose cells without contamination by any other cellular component. As yet, morphological investigations have not kept up with biochemical ones, and little is known about the ultrastructural aspects of isolated adipose cells. The present study describes the precautions required during the preparation of isolated adipose cells for study with the electron microscope. These cells are lipid “droplets” surrounded by an extremely thin cytoplasmatic layer and their fragility requires special precautions: 1. the cells must be carefully handled at all stages of preparation, avoiding mechanic or chemical trauma; 2. only small numbers of cells should be processed at any one time; 3. fixation requires a relatively high concentration of osmium to prevent continued partial solubility of the triglycerides in the solvents used for dehydration. It would seem that osmium modifies the solubility of triglycerides, probably through reaction at the level of the double bonds, perhaps facilitating cross-linkage between triglycerides at the level of the double bonds of the fatty acids involved; 4. either Vestopal or Epon can be used for embedding, Epon being somewhat easier to handle technically. Isolated adipose cells resemble in most aspects cells fixedin situ, while presenting one added particularity. In the isolated, spherical fat cell, the fat droplet is isolated from the cytoplasm by a membrane, which is itself associated with numerous saccules of smooth endoplasmic reticulum along the cytoplasmic surface of the membrane.
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  • 16
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    AIChE Journal 14 (1968), S. 37-45 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This paper illustrates the synthesis of nonlinear feedforward controllers for chemical reactors. In most of the theoretical development and application of feedforward control only linear systems have been considered. There are, however, no inherent linear limitations in feedforward control. Since chemical reactors are usually nonlinear, the effectiveness of control should be improved by including nonlinearities in the design of feedforward controllers. This is particularly true for batch reactors because of the large changes in variables during a batch cycle. Continuous stirred-tank reactors are studied with single and consecutive reactions of first and higher order. Effectiveness of linear and nonlinear feedforward controllers is compared for disturbances of various magnitude and direction. Feedforward control of batch and tubular reactors is also discussed.
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    AIChE Journal 14 (1968), S. 57-61 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The effect of standing waves of controlled amplitude and frequency on the steady state rate of mass transfer through thin horizontal liquid layers is studied experimentally. The variables studied are the film thickness, the amplitude and frequency of the waves, and the spacing between the probes generating the waves. A bulk motion of complicated pattern known as drift is caused by the finite amplitude of the waves. The rate of mass transfer in the absence of imposed vibration is two to three times greater than that expected by molecular diffusion alone. Vibration increases the rate up to an order of magnitude or more, depending on the hydrodynamic conditions. The data at low frequencies are correlated by an expression of the form (i-io)/idiff = KAf3/4h1/2L-1/2.
    Additional Material: 6 Ill.
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    AIChE Journal 14 (1968), S. 85-91 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A general method has been developed for controlling deterministic systems described by linear or linearized dynamics. The discrete problem has been treated in detail. Step-by-step optimal controls for a quadratic performance index have been derived. The method accommodates upper and lower limits on the components of the control vector.A small binary distillation unit was considered as a typical application of the method. The control vector was made up of feed rate, reflux ratio, and reboiler heat load. Control to a desired state and about a load upset was effected.Calculations are performed quite rapidly and only grow significantly with an increase in the dimension of the control vector. Extension to much larger distillation units with the same controls thus seems practical.
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  • 19
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    AIChE Journal 14 (1968), S. 235-241 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The extraction of lanthanum and barium from single falling drops of the uranium-chromium eutectic into magnesium was studied at 1,000°C. Because of the short contact times involved, the data best fit the stagnant diffusion model for lanthanum. For barium, the fraction extracted was governed by external resistance of the magnesium phase. Drop velocities were adequately represented by the Hu-Kintner correlation.
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  • 20
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    AIChE Journal 14 (1968), S. 260-265 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The external velocity field associated with the fall of a single drop through a quiescent liquid phase is discussed. The field responsible for the transfer of vorticity from the point of generation to the disperse phase is assumed to be almost identical with the field that transfers mass from the drop interface. The stream surfaces associated with this field are made visible by means of dye trails. Since the field is not amenable to mathematical formulation, and since many reports appear in the literature concerning correlations between measurable flow parameters and the physical properties of the system, the field configurations relative to mass transfer mechanisms are considered qualitatively. The delineation of the flow patterns behind the drop gives some indication of the manner in which the external flow contributes to the transfer coefficients.
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  • 21
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    AIChE Journal 14 (1968), S. 275-279 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This paper presents an investigation of the equations of motion to find the conditions under which these equations admit exact viscometric solutions for certain unsteady torsional flows of incompressible simple fluids. In general, for the cone and plane and the parallel disk geometries, curvilineal solutions do not exist for arbitrary members of the class of simple fluids; however, if the inertia terms can be neglected in the equations of motion, curvilineal solutions can be found for the complete class of simple fluids.
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    AIChE Journal 14 (1968), S. 301-310 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This paper presents a theoretical study of the stability of chemical reaction on the external surface of a single spherical particle in stagnant surroundings. The analysis, which invokes methods of linear stability theory, yields necessary and sufficient conditions for stability of a steady state solution to small disturbances for the cases of very small and very large solid thermal conductivity. It is shown that heat losses from the solid surface may lead to transient behavior which is characteristically different from that for adiabatic surfaces, and that the unsteady state is strongly affected by the thermal capacity of the solid material. A numerical example is employed to illustrate the possible significance of unstable situations.
    Additional Material: 7 Ill.
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  • 23
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    AIChE Journal 14 (1968), S. 311-317 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A comparison of the kinetic and diffusional models for solid-gas reactions occurring in a spherical particle is presented. The similarities and differences of the unreacted-core shrinking model and the homogeneous model are examined in light of the rate-controlling factors. In view of the similarity of the two models, it is shown that erroneous conclusions in regard to the mechanism and the activation energies may be drawn from an analysis of the experimental data. A more versatile model is presented in order to augment the two models so that wider varieties of solid-gas reaction systems may be treated. The concept of effectiveness factors in solid-gas reactions is introduced, and the influence of diffusion is ascertained.
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    AIChE Journal 14 (1968), S. 350-351 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
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    AIChE Journal 14 (1968), S. 356-356 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
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  • 26
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    AIChE Journal 14 (1968), S. 368-368 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
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  • 27
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    AIChE Journal 14 (1968), S. 371-371 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
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    AIChE Journal 14 (1968), S. 523-525 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
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  • 29
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    AIChE Journal 14 (1968), S. 370-526 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
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    AIChE Journal 14 (1968), S. 295-300 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In a previous paper, an analogy was presented which related the rise velocity of bubbles in liquids of infinite extent to the velocity of surface waves over infinitly deep liquids. In the present paper, a corresponding analogy is found which relates bubble velocities in bounded liquids to wave velocities over liquids of finite depth.
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  • 31
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    AIChE Journal 14 (1968), S. 392-397 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In gas-metal permeation, diffusion is normally considered to be the rate-controlling step. In addition, the diffusivity is usually taken to be independent of concentration. Under these conditions, the time lag (a characteristic of the system which depends on the time required to achieve steady state flow) is found to be (and theoretically should be) independent of the gas pressure applied to the inlet surface of the metal membrane. Furthermore, the time lag can then be directly related to the diffusivity of the system.In this paper, data on the hydrogen type 321 stainless steel system are presented which show a pronounced effect of pressure on measured values of the time lag. Taken alone, these data can be explained either by a concentration-dependent diffusivity or by resistance to flow at the metal surface. From steady state data it is shown that surface resistance is the better explanation. A model of the permeation process is presented which is consistent with the time lag data, and an estimate is made of the diffusivity of hydrogen in type 321 stainless steel.The variables studied were hydrogen pressure at the entrance surface of the membrane (0.1 to 30.0 atm.), temperature (300° to 800°C.), and membrane wall thickness (0.0252 to 0.2475 cm.).
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  • 32
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    AIChE Journal 14 (1968), S. 415-420 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A packed bed model has been adopted to develop a general correlation applicable to the flow of Newtonian fluids through all types of woven metal screens. Both of the main theoretical approaches to studying pressure drop in packed systems have been used by visualizing the screen as a collection of submerged objects with surface area to unit volume ratio a for laminar flow, and as a bundle of tubes of diameter D for turbulent flow. In the usual manner viscous and inertial energy losses are added to give an expression for the total pressure loss. Rearrangement of the general equation to the form of a friction factor yields a unique definition of the Reynolds number for screens NRe = ρu/μa2D. Procedures are described for collection of pressure drop-velocity data for the flow of nitrogen and helium through plain square, full twill, fourdrinier, plain dutch, and twilled dutch weaves. The data are used to derive a viscous resistance coefficient α = 8.61 and an inertial resistance coefficient β = 0.52. The validity of the correlation equation is tested by using additional data from the literature. The correlation successfully predicts pressure drop for a Reynolds number range of 0.1 to 1,000, void fractions from 0.35 to 0.76, screen pore diameters from 5 to 550 μ, mesh sizes from 30 to 2,400 wires/in., and surface area to unit volume ratios from 1,200 to 29,000 ft.-1.
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    AIChE Journal 14 (1968), S. 352-352 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 1 Ill.
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    AIChE Journal 14 (1968), S. 357-357 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
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    AIChE Journal 14 (1968), S. 363-363 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
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    AIChE Journal 14 (1968), S. 372-379 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Pool nucleate boiling heat transfer curves for pure nitrogen, oxygen, argon, methane, and carbon tetrafluoride have been measured on a horizontal, flat, circular, platinum plated disk for saturation pressures ranging from 1 atm. or less to the immediate vicinity of the critical pressure for each liquid. The results have been compared with various suggested nucleate boiling correlations, and the correlations of McNelly, of Kutateladze, and of Borishanskiy-Minchenko are found to be roughly equally successful and all distinctly superior to those of Rohsenow, of Gilmour, and of Forster and his collaborators for these liquids. For oxygen, argon, methane, and carbon tetrafluoride, boiling hysteresis of a type not previously reported was observed at intermediate and high saturation pressures on this surface.
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    AIChE Journal 14 (1968), S. 388-391 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The movement of solids associated with the rise of a single gas bubble in an incipiently fluidized bed has been determined. The bulk volume, measured at the porosity of incipient fluidization, of tracer solid which is transported across the original interface between undyed glass spheres in the upper region and dyed glass spheres (tracer solid) in the lower region, is approximately 30% of the bubble volume. The measurements relate to bubble volumes from 14 to 200 ml. in a glass column, 4 in. diam. Solids used were glass spheres of diameter 380 μ. The profile created when a bubble rises through a layer of fluidized tracer solids into the fluidized solids above the tracer layer has been approximately determined. The distance by which the solids were displaced upward, due to the passage of the bubble, was found to be greater than would have been the case if the behavior were that of a sphere in an inviscid liquid.
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    AIChE Journal 14 (1968), S. 411-414 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The profile of a growing droplet was determined with a pressure balance which was similar to that derived by Laplace for the static droplet. An additional term was added to the balance to account for the pressure on the interface due to the motion of the fluid within the droplet. The entire pressure balance was then combined with differential equations describing the geometry of the droplet. Computed profiles compared favorably with those obtained experimentally.An additional result was the definition of a parameter, f, indicating the importance of internal fluid motion on the shape of the profile. A method of estimating this parameter without solving the equations was developed.
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    AIChE Journal 14 (1968), S. 426-434 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A Bench-scale size fluidization system was constructed for the purpose of conducting experiments to determine density and pressure fluctuations in gas fluidized beds. Density fluctuations and bubble sizes were measured with a photocell device and β-ray absorption. Pressure fluctuations were determined with a conductivity cell. The frequency distributions of the density and pressure fluctuations and bubble sizes were determined as functions of several variables. They could be described by dimensionless coefficients and X2-distributions with different degrees of freedom. Such variables as distance from the gas distribution plate, bed height, particle size, gas flow rate, and internal screens were considered.
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    AIChE Journal 14 (1968), S. 421-425 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Dialysis of binary aqueous solutions of several sugars through a cellophane membrane was studied in a stirred batch dialyzer. Sherwood numbers describing mass transfer resistance in the fluid adjacent to the membrane were determined as a function of the corresponding Reynolds and Schmidt numbers. The results establish a reproducible environment for membrane testing in which a known controllable and small interfacial resistance is placed in series with that of the membrane. The results are also shown to support, for this geometry, the postulation of a third power relationship between eddy diffusivity and dimensionless distance from the phase boundary as well as the Sherwood-Ryan nondimensionalization of this distance.
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  • 41
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    AIChE Journal 14 (1968), S. 458-467 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A method is developed for predicting rates of gas absorption into laminar rippling films in terms of the surface velocities. The description is an extension of the surface-stretch model of mass transfer (1) and is therefore useful for cases of high Peclet number. The description can be used with any of the presently known hydrodynamic models of rippling films and with any future models which may be developed, provided they satisfy two relatively nonrestrictive conditions: (1) the ripples are of a two dimensional nature, being of constant thickness in the direction normal to their direction of propagation, and having no velocity components in this transverse direction; and (2) the ripples propagate at constant celerity and with constant shape. It can be used for both traveling and standing waves and can be extended to describe the effects of high net-mass transfer rates and combined diffusion and chemical reaction.
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  • 42
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    AIChE Journal 14 (1968), S. 473-479 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Experimental data and a mathematical model for the dehydrogenation of cyclohexane on a platinum-on-alumina catalyst in the presence of excess hydrogen are presented. Differential rate data were obtained by using a fixed bed flow reactor over a temperature range of 400° to 500°C., and a pressure range of 21.3 to 41.8 atm. at modified Reynold's numbers of 20 to 65. Cyclohexane concentration was varied from 16 to 25 mole %. In the development of the basic model, complete transport control of the overall reaction rate with equilibrium at the fluid external surface interface is assumed. The average deviation between experimentally determined and basic model calculated rates was 5.65%.Modification of the model by replacing the equilibrium assumption by a crude surface rate expression resulted in a reduction in average deviation to 4.3% and the maximum deviation was reduced from 22 to 12%.
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  • 43
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    AIChE Journal 14 (1968), S. 490-496 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A finite difference method combined with the quasilinearization technique is used to solve the nonlinear two-point boundary value problems. This method does not have the stability problem connected with the marching integration techniques. A scheme which can be used to reduce the rapid access memory requirements of digital computers is also proposed. The steady state equations resulting from mass and energy balances in a tubular reactor with axial diffusion are solved by this method. With very poor initial approximations, only three to seven iterations are needed to obtain the correct answer.
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  • 44
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    AIChE Journal 14 (1968), S. 650-650 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
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  • 45
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 2 Ill.
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  • 46
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    AIChE Journal 14 (1968), S. 658-659 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 3 Ill.
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  • 47
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    AIChE Journal 14 (1968), S. 661-662 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
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  • 48
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    AIChE Journal 14 (1968), S. 666-667 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 2 Ill.
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  • 49
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    AIChE Journal 14 (1968), S. 671-673 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 1 Ill.
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  • 50
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    AIChE Journal 14 (1968), S. 673-673 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
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  • 51
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    AIChE Journal 14 (1968) 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
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  • 52
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    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Various modifications of the Prandtl mixing-length model for turbulent momentum transport in pipes and between parallel plane walls are discussed. The most complete modification, due to Gill and Scher, is improved by replacing one of their two empirical constants by a theoretically calculable parameter. The new theory is compared with experimental data from the literature and found to reproduce frictional resistance data accurately for all values of the Reynolds number. It is somewhat in error for velocity profiles at high Reynolds numbers, but accurately reproduces velocity profile data in the transition region. The new theory represents the first accurate semi-theoretical calculation of frictional resistance coefficients for all regimes of flow (laminar, transitional, and turbulent) for both pipes and parallel plane ducts, and of velocity profiles in the transitional flow regime in either geometry.
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  • 53
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    AIChE Journal 14 (1968), S. 703-708 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An analysis of oxygen absorption by blood flowing through a small oxygen-permeable fiber in steady state laminar flow is presented. The rigidity and geometry of the fibers eliminate unpredictable shunting and distention, permitting a more detailed analysis of blood-membrane factors than has previously been undertaken. The mathematical analysis treats the blood as a homogeneous, non-Newtonian fluid with a reversible nonlinear oxygen sink (erythrocytes). The differential equations are solved numerically and the results of the parametric analysis are presented. The parameters that have a major influence on residence time necessary to obtain a specified oxygen content are the Grashof number, the concentration of hemoglobin in the blood, and wall Nusselt number, γ: γ = DLαL/DMαM In [1 + tm/R] where D = diffusion coefficient, α = Bunsen solubility coefficient, subscript L = liquid in tube, subscript M = tube material, R = inner radius of tube, tm = tube wall thickness.Comparison of the experimental results to the model indicate that mixing due to the heterogeneous nature of blood is minimal and that the major limitation in oxygen absorption is the blood film. Means of reducing this resistance are discussed.
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  • 54
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 55
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    AIChE Journal 14 (1968), S. 866-869 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A study was made to evaluate pulses as a forcing function on a 24-plate distillation column. Pulses of two shapes, rectangular and displaced cosines, and of different widths were used as inputs to the reflux return line from the condenser to the column. The effect of the disturbance was a change in the liquid return rate which correspond to the shape and size of the pulse. The output responses of the system were temperatures measured at different times and at different plates in the column.Bode diagrams were plotted from the experimentally determined data. From these plots, it was determined that the system could be approximated by linear first-order equatons. The time constants for the linear system were determined both by direct sinusoidal forcing and by pulse forcing. Pulse data were considered acceptable when the values of the time constant and the phase angle determined by the pulse compared favorably with those determined by steady state sinusoidal forcing.
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  • 56
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    AIChE Journal 14 (1968), S. 903-908 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Free convective effects on forced convective mass transfer in the Stokes flow region were studied experimentally by using a single drop in a liquid-liquid system.Liquids used to form the drops were methyl acetate or 2-ethoxyethyl acetate with distilled water as the continuous medium. Spherical drops were formed on the capillary tip of a 0.58 cm. O.D. capillary glass tube centered in a 2.5 cm. O.D. pyrex tubular flow cell.Results are presented graphically as NSh vs. NPe, NSh vs. NRe, and NSh/NRa1/4 vs. NPe to show the variation of mass transfer with flow rate and free convection. The range of variables was 10 ≤ NPe ≤35,000; 0.1 ≤ NRe ≤ 30; 578 ≤ NSc ≤ 1,149; and 12.3 ≤ NGr ≤ 75.7.Satisfactory comparisons were also made with other investigators' findings.Results substantiate that at low flow rates (Reynolds number 〈 10, Peclet number 〈 1,000) free convective effects either reinforce or interfere with mass transfer. This interference takes place until flow becomes high enough to overcome interfering effects of free convection.
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  • 57
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    AIChE Journal 14 (1968), S. 934-939 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: If the transient equations of a plug flow tubular reactor are transformed into a set of corresponding ordinary differential equations, stability information for the former may be obtained graphically from knowledge about the transients of the latter. The analysis presented in this paper combines this simplification with the definitions and theorems of Weiss and Infante to propose a method of direct computation whereby transient bounds may be found for this important class of distributed-parameter chemical reactor systems.
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  • 58
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    AIChE Journal 14 (1968), S. 813-813 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 59
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    AIChE Journal 14 (1968), S. 946-955 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This paper presents the cause of instabilities which arise during the numerical solution of ordinary differential equations. By using the numerical integration routines presently available, one actually approximates the differential equation by a difference equation. If the difference equation is of a higher order than the original differential equation, the approximate solution contains extraneous solutions which are not at all related to the true solution. It is the behavior of these extraneous solutions that one is usually concerned with in a stability analysis.Also presented is a procedure for obtaining a bound on the largest allowable integration step size for a class of chemical engineering problems. A detailed explanation of the procedure is illustrated for unsteady state distillation calculations.
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  • 60
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    AIChE Journal 14 (1968), S. 966-969 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 6 Ill.
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  • 61
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    AIChE Journal 14 (1968), S. 977-979 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
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  • 62
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    AIChE Journal 14 (1968), S. 986-988 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 3 Ill.
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  • 63
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    AIChE Journal 14 (1968), S. 762-771 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A new method for determining adsorption equilibrium constants, rate constants, and intraparticle diffusivities is described and applied for the adsorption of ethane, propane, and n-butane on silica gel. The method rests upon recently developed theory for relating the moments of the effluent concentration wave from a bed of adsorbent particles to the rate constants associated with the various steps in the overall adsorption process. It is necessary to operate at concentrations of adsorbable gas such that the adsorption isotherm is linear. However, it is possible to take into account effects of longitudinal dispersion and diffusion to the particle surface as well as the intraparticle processes of diffusion and adsorption on the pore surface.The method gave reasonable values for intraparticle diffusivities and adsorption rate constants. Intraparticle diffusion was a major resistance for all particle sizes studied and for the largest size (R = 0.50 mm.) this step controlled the overall rate.From the constants determined chromatographically it is possible to predict breakthrough curves for the adsorption of these hydrocarbons on silica gel. The predicted curves agree well with experimentally established breakthrough curves.
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  • 64
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    AIChE Journal 14 (1968), S. 805-806 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 3 Ill.
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  • 65
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    AIChE Journal 14 (1968), S. 809-811 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
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  • 66
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    AIChE Journal 14 (1968), S. 816-817 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 67
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    AIChE Journal 14 (1968), S. 825-826 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
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  • 68
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    AIChE Journal 14 (1968), S. 835-836 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 69
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    AIChE Journal 14 (1968), S. 886-895 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A new method, based upon chromatography, was used to measure surface diffusion coefficients for ethane, propane, and n-butane on silica gel. The diffusivities correspond to very low surface coverages (fraction of a monolayer of the order of 10-4) and hence should represent limiting values. A survey of available surface diffusion information, all at higher coverages, indicated that the results reported here are at the lower end of the range of diffusivities. The activation energy and heat of adsorption, for example, for n-butane, were 4.4 and -7.8 k cal./mole, respectively.Surface diffusion was a significant fraction of the total intraparticle mass transport, in part because in the small pores in silica gel gas phase diffusion was solely by the Knudsen mechanism. For propane, surface migration was 73% of the total transport at 50°C. and 61.5% at 125°C.
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  • 70
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    AIChE Journal 14 (1968), S. 917-922 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A study has been made of the expansion characteristics of beds of uniformly sized spherical particles of lead, nickel, sand, glass, and plastic that have been fluidized with air, carbon dioxide, and helium in columns packed with open-ended cylindrical screen packing. The addition of packing to a gas-fluidized bed limits the bubble size, prevents slugging and allows beds of high aspect ratio to expand smoothly in a manner similar to the behavior of liquid-fluidized beds. Moreover, much of the experimental data for gas-fluidized screen-packed beds have yielded straight lines on a Richardson-Zaki type of plot, again similar to the expansion of liquid-fluidized beds. The conditions necessary for this pseudoparticulate behavior in packed gas-fluidized beds are discussed. A correlation, based on the analysis given by Richardson and Zaki for liquid-fluidized beds, is proposed to relate bed porosity with gas velocity, density and viscosity, particle size and density, and bed diameter.
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  • 71
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    AIChE Journal 14 (1968), S. 939-946 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Convective diffusion in laminar flows which develop from rest and in the velocity entrance region of tubes, is studied. Criteria for the validity of the simple dispersion model are established by comparison of analytical results with numerical experiments.It is found that the extent of dispersion is less in developing velocity fields than in those which are fully developed. This occurs because dispersion is enhanced by differences in the velocity of the fluid particles on a plane perpendicular to the main direction of flow. Such differences are greatest when the flow is fully developed.
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  • 72
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    AIChE Journal 14 (1968), S. 956-961 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A theoretical study was made of transient diffusion to a body immersed in a finite volume of well-stirred fluid. The major contribution of this work was the development of a technique for solving the problem for a three-dimensional body of arbitrary shape. The solutions are in a form that is useful for determining diffusion coefficients insolids by means of the constant-volume experimental technique.The partial differential equation coupled with the ordinary differential equation describing the diffusion process is transformed into a single integral equation in terms of the solute concentration in the reservoir. A numerical technique is then presented for solving the integral equation. Numerical solutions were computed for the three geometries that possess analytical solutions: the infinite slab, the infinite cylinder, and the sphere. By properly choosing the step-size numerical results were easily obtained that agreed with the exact solution to four decimal places.New solutions were computed for two three-dimensional geometries: the finite cylinder and the rectangular prism. A range of shape factors and ratios of the volume of the reservoir to that of the solid body were employed for each geometry. It was shown that by selecting the ratio of volume to external surface area as the characteristic length of each shape object, the solutions for all shapes were brought close together and were identical during the initial part of the transient.
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    AIChE Journal 14 (1968), S. 973-975 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
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  • 74
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    AIChE Journal 14 (1968), S. 983-983 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
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    AIChE Journal 14 (1968), S. 993-993 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
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    AIChE Journal 14 (1968), S. 118-122 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Empirical size-dependent growth rate models are studied for their effect on the population density distributions from a continuous, mixed suspension, mixed product removal (CMSMPR) crystallizer. The growth rate models and/or their corresponding population density distributions are examined for continuity, convergence of moments, versatility, and their ability to fit experimental data.A new empirical size-dependent growth rate model is proposed which has properties superior to those of previous models. Experimental steady state data are presented to illustrate the application of the model to actual CMSMPR crystallization systems.
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    AIChE Journal 14 (1968), S. 135-144 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A critical discussion is given of the use of local compositions for representation of excess Gibbs energies of liquid mixtures. A new equation is derived, based on Scott's two-liquid model and on an assumption of nonrandomness similar to that used by Wilson. For the same activity coefficients at infinite dilution, the Gibbs energy of mixing is calculated with the new equation as well as the equations of van Laar, Wilson, and Heil; these four equations give similar results for mixtures of moderate nonideality but they differ appreciably for strongly nonideal systems, especially for those with limited miscibility. The new equation contains a nonrandomness parameter α12 which makes it applicable to a large variety of mixtures. By proper selection of α12, the new equation gives an excellent representation of many types of liquid mixtures while other local composition equations appear to be limited to specific types. Consideration is given to prediction of ternary vapor-liquid and ternary liquid-liquid equilibria based on binary data alone.
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    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 14 (1968), S. 77-84 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Locally linearized equations for dynamic disturbances from a steady state have been solved analytically for an adiabatic chemical reactor with chemically inert packing and a homogeneous chemical reaction. The solutions, in the form of transfer functions, include the effects of heat capacity of the packing and heat transfer between the packing and the fluid, as well as the coupling effects of chemical reaction and the associated heat generation.Several limiting cases of the transfer functions are discussed and the transfer functions are simplified by an approximation of the temperature dependence of the reaction rate. Frequency responses and step responses of the reactor are calculated from the transfer functions.
    Additional Material: 8 Ill.
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  • 79
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    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 14 (1968), S. 169-173 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: One of the greatest difficulties in the analysis of mixing operations for powders is that of specifying the degree of mixedness in a quantitative manner. This problem is studied for on idealized model. A precise index of the degree of mixing is found for this model, which holds promise of being useful for real mixtures. It is shown that samples of a single size provide all the necessary information. The effect of sample size is defined quantitatively, and a minimum sample size is recommended.
    Additional Material: 3 Ill.
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  • 80
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    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 14 (1968), S. 32-37 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Inequalities are derived for a general class of convex-functional means which may contain negative weights. Specific cases include the arithmetic-mean-geometric-mean inequality and other power-mean inequalities. These inequalities make possible the solution of a wider class of extremum problems than are susceptible to the classical means with positive weights. In particular, it is shown that the geometric programming algorithm may in some cases be extended to functions with negative coefficients. A weaker result is derived for application without restrictions on the signs of the coefficients or variables. This leads to a computational scheme which is useful in the solution of certain classes of nonlinear programming and inequality-constrained multistage optimization problems.
    Additional Material: 2 Ill.
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  • 81
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The selective, highly endothermic reaction of methylcyclohexane to toluene and hydrogen was studied experimentally over a commercial Pt/Al2O3 catalyst, in an electrically heated tube serving as a packed-bed reactor heat exchanger. The constant-flux reactor, with measurement of temperatures within the bed at points intermediate along its length, proved well suited as an integral reactor for providing information on the reaction rate. A simple analytical model of the reactor was developed, and some of the data were used with the model to derive a rate expression.The model gives a good representation of radial variation of temperature in the packed bed. In the region of high Reynolds numbers investigated, radial transport of enthalpy is described in the model by a film resistance at the tube wall defined by heat transfer coefficient, and a diffusive transport through the packing, dominated by eddy diffusion.
    Additional Material: 9 Ill.
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  • 82
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An approximate theory for transient dispersion with combined free and forced convection in vertical tubes is developed and tested experimentally. It is found that the dispersion coefficient in such systems depends on a parameter α, which is defined by Equation (38). The analytical expression developed for the dispersion coefficient, Equation (33), is found to be a reasonably good approximation in the range -50 〈 α 〈 300.Experimental results are reported for a rather wide range of parameters for tubes with both 1 1/2 and 5 mm. diameters.It is found that the extent of dispersion is enhanced significantly when lighter fluid is on the bottom and displaces a heavier one. On the other hand, the dispersion coefficient is inhibited when the situation is reversed. It is found that these effects are not symmetrical with respect to the absolute magnitude of the parameter α as is illustrated in Figure 12.
    Additional Material: 13 Ill.
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  • 83
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    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 14 (1968), S. 123-127 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The theoretical equations for the flow of Newtonian fluids in a falling cylinder viscometer with eccentricity are developed. The error in fall velocity of the cylinder caused by eccentricity is determined and presented in tabular form. An approximate method to determine the error in fall velocity caused by eccentricity for non-Newtonian fluids of the power law type is also presented. For the Newtonian case, n=1, the approximate method is shown to give excellent agreement with the exact method.
    Additional Material: 3 Ill.
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  • 84
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A correlational procedure was developed to predict the vapor liquid equilibrium behavior of light hydrocarbons in heavier hydrocarbon solvents at low temperatures and elevated pressures. The method is applicable to paraffinic as well as aromatic solvents.The method employed the Benedict-Webb-Rubin equation of state to predict the vapor phase fugacities. Methane liquid fugacities in the various hydrocarbon solvents were based upon Henry's law which included terms to account for compositional and pressure effects. The liquid fugacities for ethane and propane were calculated using infinite dilution data to modify empirically the Scatchard-Hildebrand equation. Excellent agreement between the correlated and low-temperature data available on this class of systems was obtained.
    Additional Material: 14 Ill.
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  • 85
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    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 14 (1968), S. 159-164 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The intrinsic kinetics of the hydrogenolysis of thiophene on a cobalt molybdate catalyst were studied in a differential reactor with recirculation, at a total pressure of about 1 atm. and temperatures of 235° to 265°C. Retardation of the reaction by both thiophene and hydrogen sulfide was significant and the rate of thiophene disappearance was correlated by a Langmuir-Hinshelwood type of kinetic equation. Hydrogenation of the butene intermediate was inhibited by both butene and hydrogen sulfide and the rate of this reaction was also described with a Langmuir-Hinshelwood rate equation. The forms of the kinetic expressions obtained imply that the butene is not hydrogenated at the original desulfurization site.
    Additional Material: 3 Ill.
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  • 86
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    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 14 (1968), S. 173-180 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 2 Ill.
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  • 87
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    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 14 (1968) 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 88
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    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 14 (1968), S. 210-364 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 89
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    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 14 (1968), S. 211-221 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This work is a study of the stability of a batch fluidized bed with a simple model. It is shown that multiple steady states can occur with all catalyst particles at the same temperature, some of these states being unstable. If the initial temperature of all the particles is not the same, a special kind of steady state, in which particles of different temperatures can coexist in the bed, might be obtained. The number of these pathological steady states is not finite, and the conversion obtained may be very different from that obtained by a uniform steady state.The analysis has demonstrated that the initial temperature of the catalyst particles may be a predominate factor in determining the kind of steady state obtained. For the case of uniform catalyst particles, a simple stability analysis has been developed. Several numerical solutions of the transient equations were performed to investigate the possible responses of the system to disturbances of various steady states.
    Additional Material: 11 Ill.
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  • 90
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    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 14 (1968), S. 242-244 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 3 Ill.
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  • 91
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    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 14 (1968), S. 266-274 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An apparatus and experimental technique were developed for the study of the kinetics of relatively rapid reaction and subsequent crystallization in condensed phases. The method employs batch experiments to establish the integral of crystallization rate over ranges of pertinent external variables.The crystallization of potassium dipicrylamine from aqueous solution, a system of potential interest in application to potassium recovery from brines, was studied experimentally. It is shown that both reaction and crystallization rate parameters may be determined from the data on the basis of the consecutive rate model developed; application of the Burton-Cabrera-Frank theory of crystal growth to this system is demonstrated.
    Additional Material: 12 Ill.
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  • 92
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    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 14 (1968) 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 93
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
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  • 94
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    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 14 (1968), S. 286-294 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A rigorous analysis of jet hydrodynamics is used to develop a technique for determining diffusion coefficients from laminar liquid jet absorption experiments, and the influence of the jet fluid mechanics on the absorption process is clarified. The new technique is used to determine the diffusivities of carbon dioxide, oxygen, argon, nitrous oxide, ethylene, and propylene in water within the temperature range 25° to 40°C.A critical analysis of available diffusivity data for these gases indicates that there is no conclusive evidence that demonstrates the existence of a significant interfacial resistance in uncontaminated laminar jet experiments. In addition, comparison of existing data shows that the commonly accepted diffusivities for the oxygen-water system may be significantly higher than the actual values. It is concluded that the laminar jet experiment is a rapid, accurate method of obtaining diffusion coefficients of dissolved gases in liquids.
    Additional Material: 8 Ill.
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  • 95
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    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 14 (1968), S. 325-330 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 7 Ill.
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  • 96
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    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 14 (1968), S. 331-334 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The characteristics of cylindrical particles settling in the Stokes regime in a bounded fluid are discussed. Applicable theory is reviewed and experimental data showing the effect of orientation on the terminal velocity are presented.
    Additional Material: 4 Ill.
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  • 97
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    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 14 (1968), S. 351-351 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 98
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    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 14 (1968), S. 448-452 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The concept of a continuous mixed suspension-mixed product removal crystallizer was used both as an analysis and experimental tool to study the effects of suspension density on crystal size distribution. If the crystals present in suspension are not a source of nuclei, larger crystals will be obtained in the presence of higher suspension densities. If the rate of new particle formation is proportional to the amount of crystals present, the crystal size obtained will not be changed by the suspension density level. There was evidence of nucleation rate dependency on the quantity of suspended crystals in the two systems studied experimentally.
    Additional Material: 5 Ill.
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  • 99
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    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 14 (1968), S. 452-457 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The nucleation kinetics of three materials were related to the growth kinetics using steady state data obtained at various degrees of supersaturation. The power models obtained from the three crystallizaitons exhibited widely different kinetic orders. These materials were then crystallized under unsteady state conditions in a mixed suspension-mixed product removal crystallizer and the transient size distributions were determined. The unsteady state model previously developed by Randolph and Larson was solved on a digital computer for the three systems. Good agreement was obtained. It was found that unsteady state experiments have some advantages over steady state experiments in determining the kinetic order of nucleation.
    Additional Material: 9 Ill.
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  • 100
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    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 14 (1968), S. 497-499 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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