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  • 1970-1974  (27,591)
  • 1890-1899  (12,616)
  • Chemistry  (39,783)
  • Electron microscopy  (425)
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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Anatomy and embryology 143 (1974), S. 215-222 
    ISSN: 1432-0568
    Keywords: Lung ; Stretch receptors ; Light microscopy ; Electron microscopy ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Lappenbronchien (3./6.) (Durchmesser bei mittlerer Inspirationslage 500–700 μ) von männlichen und weiblichen Wistarratten wurden licht- und elektronenmikroskopisch untersucht. Diese Bronchien entsprechen im Wandbau den mittleren Bronchioli größerer Säugetiere. Freie, verzweigte lanzettförmige Terminalfasern werden im Bindegewebe der lamina propria beschrieben. Sie sind in das elastisch muskuläre System der Bronchuswand eingebaut. Die zugehörige markhaltige afferente Nervenfaser ist verzweigt und hat einen Durchmesser von 4–6 μ. Außerdem werden efferente motorische Endigungen an der glatten Bronchialmuskulatur beschrieben. Die freien lanzettförmigen und verzweigten Terminalfasern sind möglicherweise Dehnungsrezeptoren für den Hering Breuer Reflex.
    Notes: Summary In rats the 3rd to 6th bronchi, measuring 500–700 μ in diameter during inspiration, were investigated by light and electron microscopy. The histological appearance of these bronchi is comparable to that of medium sized bronchioles of larger animals. The branched and lanceolate terminals are associated with the connective tissue of the lamina propria and the smooth muscle cell layer. In this way the terminals are bound to the myoelastic system of the bronchial wall. The myelinated afferent fiber is branched and the diameter measures about 4–6 microns. Besides afferent nerve terminals these are numerous efferent endings on the smooth muscle basement laminae. It is supposed that the described receptor represents the pulmonary stretch receptor of the Hering Breuer reflex.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Anatomy and embryology 147 (1974), S. 19-34 
    ISSN: 1432-0568
    Keywords: Gonads/embryology ; Swine/embryology ; Sex determination ; Electron microscopy ; Sex characteristics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Pig embryos aged 21–22 days (d) were obtained from artificially inseminated sows for an ultrastructural study of the development and sex differentiation of the gonadal ridge. The chromosomal sex of the embryos was identified by a chromosome analysis. At the age of 21 d the gonadal ridge consisted of three different tissue: the surface epithelium, the primitive cords, and the mesenchyme. The surface epithelial cells contained elongate mitochondria with lamellar cristae, granular endoplasmic reticulum (GER), the Golgi complex, free polysomes, coated vesicles and fine filaments. The epithelium was continuous with the primitive cords, which were composed of ultrastructurally similar cells. The epithelial basal lamina followed the cord surface, but covered it incompletely. Primordial germ cells (PGC) were located under the surface epithelium in the mesenchyme and in the cords. The nucleus with a prominent nucleolus, and the large mitochondria were round. The cytoplasm contained a pair of centrioles, the Golgi complex, solitary lamellae of the GER, free polysomes, lipid droplets and some coated vesicles. The PGC entered the gonadal cords before these were surrounded by the continuous basal lamina. A day later (22 d) the number and length of the cords were increased. The PGC were more frequent and seen also in deeper layers. All the structures studied at the age of 21–22 d showed that the gonadal ridge also at the ultrastructural level is at the sexually indifferent stage.
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  • 3
    ISSN: 1432-0568
    Keywords: Calcitonin ; C-Cells of the thyroid and cells of the parathyroid glands ; Secondary hyperparathyroidism ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Im Verlauf ein- bis achtwöchiger Behandlung von Wistar-Ratten mit täglich 300 mMRC Einheiten Schweinecalcitonin kam es in den C-Zellen der Schilddrüse, verglichen mit denen der Kontrollserien (unbehandelte und mit Acetatpuffer allein behandelte Tiere), einerseits zu einer morphometrisch signifikanten Abahme der Zahl der Sekretgranula, während andererseits sämtliche Zellorganellen (Mitochondrie,, Golgi-Apparat und auch das granuläre endoplasmatische Reticulum) besser entwickelt waren. In den in gleichen Zeitabschnitten untersuchten Parathyroideazellen fanden wir bei mit Calcitonin behandelten Ratten Strukturveränderungen, die auf eine erhöhte Aktivität hinwiesen: Einfaltungen des Kerns, Erweiterung der Intercellularräume mit Vermehrung und Verlängerung der in diese hineinragenden Mikrovilli, bessere Ausbildung des Golgi-Apparates und des granulären endoplasmatischen Reticulums sowie eine größere Menge freier Ribosomen. Die Zahl der Sekretgranula war eindeutig höher als bei den Kontrolltieren. Der Ca ++- und Mg++-Blutspiegel zeigte während der ganzen Versuchsdauer bei allen Tieren keine statistisch faßbaren Änderungen. Die Autoren vertreten die Hypothese, daß die Aktivierung der C-Zellen durch das Auftreten eines durch die Calcitoninverabreichung hervorgerufenen sekundären Hyperparathyroidismus zustande kommt.
    Notes: Summary Male Wistar rats were injected for one to eight weeks with 300 mMRC units per day of porcine calcitonin. During this period C-cells (or “parafollicular” cells) of the thyroid gland and cells of the parathyroid glands were examined ultrastructurally. The C-cells were further studied morphometrically in animals treated with calcitonin dissolved in acetate buffer as well as in acetate buffer- and not-treated control animals. In the thyroid C cells the number of secretion granules significantly decreased following calcitonin administration, whereas the volume of all cell organelles (mitochondria, Golgi complex and granular endoplasmic reticulum) augmented. The cells of the parathyroid glands of the calcitonin-treated rats showed structural changes due to higher activity: invaginations of the nuclear envelope, enlargement of the intercellular spaces with increase in number and size of the microvilli, better development of the Golgi complex and the granular endoplasmic reticulum, larger population of free ribosomes and secretory granules. However, no significant differences in the blood calcium and magnesium levels were detected when a comparison was made of calcitonin-treated and control animals. All these observations support the hypothesis that the activation of the C-cells may result from a secondary hyperparathyroidism itself induced by the administration of moderate doses of calcitonin.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Anatomy and embryology 144 (1974), S. 75-83 
    ISSN: 1432-0568
    Keywords: Colonic mucosa ; Mouse ; Vacuolated cells ; Electron microscopy ; Morphology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Swiss ICR adult male mice were used to analyse regional morphologic differences in the mucosa of the colon. The three cell types recently described in the descending colon of the mouse were also observed in the transverse and in the ascending colon. However the vacuolated cells of the crypts have presented different morphological characteristics depending on their localisation. In the ascending colon, they exhibited small supranuclear vesicles in contrast to the large vesicles observed in the descending colon. Several cell combining features of argentaffin-vacuolated, goblet-vacuolated and goblet-argentaffin cells have been observed. Furthermore a special type of granule referred to as a secondary lysosome was observed in the peripheral area of the typical goblet cells.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Anatomy and embryology 144 (1974), S. 85-100 
    ISSN: 1432-0568
    Keywords: X zone ; Electron microscopy ; Development ; Adrenal ; Mouse
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The postnatal development and involution of the X zone in the mouse adrenal cortex of both sexes were examined using the light and electron microscopes. At 0–5 days of age, no special cell group could be distinguished for the developing X zone in the inner cortex. The inner cortical cells contained spherical or ellipsoidal mitochondria with vesiculotubular cristae, vesiculotubular smooth endoplasmic reticulum (sER) and electron-lucent lipid droplets. The first sign of the developing X zone was the appearance of small groups of cells in juxtamedullary region differing from the cells in other part of inner cortex at 8 days. The electron microscopy showed that such cells contained nuclei of somewhat irregular outline and some parallel stacks of flattened sER. At 10–11 days, a thin layer of small eosinophilic cells were clearly identified as the developing X zone light microscopically in both sexes. Electron microscopically, the X zone cells showed a much dense cytoplas, which contained abundant sER, many mitochondria and numerous ribosomes. The typical X zone cells were characterized by the formation of peculiar mitochondrial complexes and whorled pattern of the sER. Mitoses were often found in the X zone, where mitotic cells even contained the whorled sER and bizarre mitochondria characteristic of the typical X zone cells. In the male the X zone rapidly involuted and might disappear by 30 days of age, whereas in the female X zone persisted as a thicker layer with the earlist sign of fatty degeneration. The origin of the X zone cell and the process of formation of its characteristic organelles are discussed.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Anatomy and embryology 144 (1974), S. 1-18 
    ISSN: 1432-0568
    Keywords: Mammals ; Mole ; Ovary ; Interstitial cells ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Das Ovar des Maulwurfs wurde licht- und elektronenmikroskopisch untersucht. Der Feinbau der verschiedenen Follikel und der Keimzellen entspricht dem anderer Species. Die Granulosa wird vermutlich erst mit der Ovulation luteinisiert. Sie enthält reichlich rauhes endoplasmatisches Reticulum und Sprossen von glattem endoplasmatischem Reticulum. Die Zellen der Theka interna leiten sich von Fibrocyten ab und enthalten neben reichlich glattem ER auch granuläres ER sowie Lipidtropfen und Mitochondrien mit Cristae und Tubuli. Diese Zellen ähneln in ihrer Feinstruktur stark den Zwischenzellen des ovarialen Marks. Dieses enthält in der Marksträngen Epithelien, die einer kräftigen Basalmembran aufsitzen. Sie werden teils als embryonal persistierende Vorstufen von Granulosa- oder Sertoli-Zellen, teils als Granulosasprossen aus der Rinde gedeutet. Für die Zwischenzellen des Marks erscheint eine Analogie mit den Hiluszellen des menschlichen Ovarialmarks bzw. eine Homologie mit den Leydig-Zellen des Hodens zweifelhaft. Als mögliche Quelle für diesen Zelltyp werden neben embryonal liegengebliebenen Anteilen auch Thekakeile und Epoophoronzellen sowie Fibroblasten diskutiert. Neben einer Steroid-synthese dürfte ihnen eine Reserve- und Speicherfunktion zukommen.
    Notes: Summary In order to make possible comparison between relatively primitive and relatively specialized gonads, the ovary of the mole was studied by light and electron microscopy. The ultrastructure of primary, secondary and tertiary follicles and of the germ cells is similar to that of other species. The granulosa cells of secondary and early tertiary follicles contain abundant rough endoplasmic reticulum and a small number profiles of smooth endoplasmic reticulum. The cells of the theca interna, which develop from simple fibrocytes are rich in smooth and rough endoplasmic reticulum and contain many lipid droplets and mitochondria, which possess both cristae and tubuli mitochondriales. At the time of ovulation, the granulosa cells are luteinized and their ultrastructure changes correspondingly. The medulla of the ovary is composed of the medullary cords and the interstitial cells. The medullary cords are solid epithelial cords, which are surrounded by a prominent basement membrane. They may be derived from embryonic precursors of granulosa—or Sertoli-cells or bud from the cortical zonae granulosae. There is a striking morphological similarity between the theca and interstitial cells. The interstitial cells of the ovarian medulla differ from the hilus cells of the human ovary and the Leydig-cells of the testis. They may develop either from embryonic rudiments of Leydig—or hilus-cell precursors, or bud from the theca or the epoophoron, or they may develop from fibrocytes. In addition to their suggested activity in steroid biosynthesis, the interstitial cells may have a trophic or storage function.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Anatomy and embryology 145 (1974), S. 187-196 
    ISSN: 1432-0568
    Keywords: Human skeletal muscle ; Sarcolemma ; Isolation ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary An isolation procedure for sarcolemma of human skeletal muscle is described. The method includes the possibility to prepare sarcoplasmic reticulum from the same muscle fibres. Electron microscopy reveals a homogeneous final fraction of 80–90% myofibre enveloping membranes contaminated by blood vessel membranes. The typical three-laminar composition of isolated sarcolemma is demonstrated. The mechanism of muscle fibre emptying is discussed.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Anatomy and embryology 146 (1974), S. 95-111 
    ISSN: 1432-0568
    Keywords: Cerebellum ; Thalamus ; Electron microscopy ; Autoradiography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary An experimental electron microscopical study has been made on the mode of termination of the cerebellothalamic projections in the cat. Supporting experimental light microscopical studies of silver impregnated sections following a large lesion of the cerebellar nuclei and light microscopical autoradiographic studies of the thalamus following injections of tritiated leucine in parts of the cerebellar nuclei, have been made as well. Following large lesions of the cerebellar nuclei, only the largest occuring type of bouton in the cat's VL and VA (type LR bouton) degenerates. Following such lesions, type LR boutons undergo a filamentous hypertrophy before becoming electrondense. One degenerating LR bouton establishes complex synapses with the dendrites of both thalamocortical relay cells and interneurons. Not all type LR boutons in VL and VA degenerate following lesions of the cerebellar nuclei. Light microscopical autoradiographic studies as well as experimental electron microscopical investigations indicate that cerebellothalamic fibers end in clusters within VL and VA, and that the areas of termination lie more rostrally within these thalamic nuclei than has been inferred from experimental studies of silver impregnated sections following lesions of the cerebellar nuclei. The findings are discussed with respect to relevant morphological and physiological data.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 16 (1974), S. 145-152 
    ISSN: 1432-0827
    Keywords: EHDP ; Bone ; Chemistry ; Serum ; Rabbits
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract The effects of disodium ethane-1-hydroxy-1,1-diphosphonate (EHDP) on bone and serum chemistry were investigated in adult rabbits. EHDP was administered by subcutaneous injection at doses of 0.25, 2.5 and 10 mg/kg body weight/day for of 28 days. Blood samples were obtained weekly from each rabbit and serum levels of total calcium, ionized calcium, inorganic phosphate and alkaline phosphatase were determined. At the end of the treatment period all rabbits were sacrificed and the tibiae removed for chemical analysis and histological evaluation. The effect of EHDP administration on serum chemistry was both dose- and time-related. The highest of the three doses, 10 mg/kg/day, resulted in a time-related decrease in total serum calcium. This dose also caused a rapid but transient reduction in serum ionized calcium. The effect of EHDP on serum inorganic phosphate was biphasic. Administration of 2.5 mg/kg/day resulted in a time-related elevation in this parameter, whereas the 10 mg/kg/day dose resulted in a time-related hypophosphatemic response. There were no significant drug-related changes in tibial fat-free dry weight, ash weight, total calcium or total phosphorus values. However, administration of 2.5 and 10 mg/kg/day EHDP resulted in increased osteoid tissue as measured histologically. These results are compared with data from other EHDP studies, and discussed in relation to the maturity and growth-state of the experimental animals.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Langenbeck's archives of surgery 335 (1974), S. 263-272 
    ISSN: 1435-2451
    Keywords: Coating ; Blood-Compatibility ; Gels ; Chemistry ; Hydrophilic Monomers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Es wurden die wichtigsten Arbeiten über hydrophile Gele ausgewählt und im Hinblick auf ihre Eignung als aussichtsreiche Blut-Kontaktmaterialien betrachtet. Die Reaktionsbedingungen werden beschrieben, und die gegenseitige Wechselwirkung von Blut und Kunststoff wird dargestellt.
    Notes: Summary By the selection of the relevant sources it is attempted to present the contemporary research situation of the hydrophilic polymeric gels as promising materials for the contact with the blood in the organism. The reaction conditions of the current syntheses are described as well as the mutual interactions of the blood and the contact surface.
    Type of Medium: Electronic Resource
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  • 11
    Electronic Resource
    Electronic Resource
    Springer
    International archives of occupational and environmental health 32 (1974), S. 129-144 
    ISSN: 1432-1246
    Keywords: Lead intoxication ; Lead line ; Electron microscopy ; Stomato-Logy ; Bleiintoxikation ; Bleisaum ; Elektronenmikroskopie ; Stomatologie
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Die histologischen Befunde beim Bleisaum im Licht- und Dunkelfeld werden kurz besprochen. Die Beobachtungen stimmen mit den bekannten Angaben aus der Literatur überein. Elektronenmikroskopische Untersuchungen an Gingivabiopsien von 3 Patienten mit Bleivergiftung und deutlichem Bleisaum zeigten, daß die Ablagerungen sowohl extra- als auch intracellulär zu finden sind. Extracelluläres Blei war hauptsächlich zwischen kollagenen Pasern, um die Blutgefäße und in die Basallamina an der dermo-epidermalen Grenze eingelagert. Intracelluläres Blei war in einer Gruppe von Zellen in membranbegrenzten Phagosomen vorhanden, während es in anderen Zellen diffus im Cytoplasma verteilt war, wobei es zu einer Einlagerung in die verschiedenen cytoplasmatischen Membransysteme, besonders in die mitochondrialen Membranen, kam. Reste von lytischen Zellen mit diffus im Cytoplasma verteiltem Metall wurden von Makrophagen aufgenommen. Es wird vermutet, daß ein Cyclus abläuft, der mit der Phagocytose von Blei beginnt und über progrediente Zellschädigung zur Lyse führt. Die Ergebnisse werden mit Beobachtungen bei Argyrose verglichen. Das unterschiedliche Verteilungsmuster der Metalle bei diesen beiden Erkrankungen wird im Hinblick auf eine Hypothese über den Pathomechanismus von Schwermetallvergiftungen diskutiert.
    Notes: Summary The histology of the lead line is briefly reviewed on the basis of light- and dark-field microscope studies. The observations correspond with published data. Electron microscope studies on gingival biopsies obtained from 3 patients with lead intoxication and marked lead lines showed extra- and intracellular deposits of the metal. Extracellular lead was preferentially deposited between collagen fibers, around blood vessels and on the basal lamina of the dermal-epidermal junction. Intracellular lead was present within membrane-bound phagosomes of one group of cells, whereas it was diffusely distributed within the cytoplasm of another cell group. In the latter it was deposited on the different cytoplasmic membrane systems, particularly on the mitochondrial membranes. Residues of lytic cells, which contained diffusely distributed metal, were phagocytized by macrophages. It is assumed that a cycle starts with the phagocytosis of lead and ends with increasing cellular damage and cytolysis. The results are compared with the observations in argyria. The different distribution patterns of the metal in the two diseases are discussed in the light of a proposed hypothesis on the pathomechanisms of heavy-metal poisoning.
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  • 12
    ISSN: 1432-1459
    Keywords: Amaurotic Idiocy ; Late infantile Neuronal ceroid-lipofuscinosis ; Mental retardation ; Electron microscopy ; Inclusion bodies ; Membrane bound neuronal
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Es werden die lichtmikroskopischen, histochemischen und elektronenmikroskopischen Befunde in der Gehirnbiopsie eines Frühfalles von später infantiler Form der amaurotischen Idiotie (oder einer frühen Form der Batten-Spielmeyer-Vogt-Krankheit) beschrieben. An die Membranen gebundene cytoplasmatische Einschlußkörperchen sind in einigen wenigen Neuronen vorhanden. Die morphologischen Befunde werden mit Bezug auf die Ätiologie der Erkrankung diskutiert.
    Notes: Summary The light microscopic, histochemical and electron microscopic findings in a brain biopsy of an early case of Late Infantile Amaurotic Idioty (early form of Batten-Spielmeyer-Vogt disease) are reported. Membrane bound cytoplasmic inclusion bodies are present in a small number of neurons. The morphological findings are discussed in relation to the etiology of the disease.
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  • 13
    Electronic Resource
    Electronic Resource
    Springer
    Journal of neurology 208 (1974), S. 1-16 
    ISSN: 1432-1459
    Keywords: Neuroblastoma, central ; N-methyl-N-nitrosourea ; Transplacentar carcinogenesis ; Neuronal differentiation ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Die transplacentare Gabe von MNH an schwangere Ratten am 16. Tage der Gravidität, obwohl sie bei allen untersuchten Nachkommen zu Gehirnmißbildungen führte, erzeugte nur einen Tumor des Nervensystems. Dieser bösartige Tumor, bei dem am Lichtmikroskop die Diagnose Neuroblastoma gestellt wurde, wurde auch durch E.M. untersucht. Obwohl Strukturen stark andeutend auf unreife oder regressive synapsenartige Kontakte vorhanden waren, konnten gutentwickelte Synapsen jedoch nicht beobachtet werden. Bei den verschiedenen neuronalen Eigenschaften, die bei den Tumorzellen zum Vorschein kamen, besonders extensive Nissl-Schollen und zahlreiche „subsurface“ Zisternen, waren mehrere typisch für die embryonale Entwicklung der Nervenzellen: geästete Zellfortsätze mit Wachstumskonen und dense core, neurosekretorische Granula; diese Granula wurde als charakteristisch für neuerwachsende Nervenfasern angesehen. Die Anwesenheit dieser Entwicklungsmerkmale in einem Nervenzellenmalignom kann die vermutete embryonale Abstammung des Neuroblastomas als Abkömmling von unreifen Formen und nicht von entdifferenzierten Zellen bestätigen.
    Notes: Summary Transplacentar administration of MNU to pregnant Wistar-R rats at the 16th day of gestation, while inducing cerebral malformations in all the offspring examined, produced only one nervous system tumor. This malignant neoplasm, diagnosed optically as a neuroblastoma, was also examined at the EM level. Although structures strongly suggestive of incipient or abortive synaptic formations were present, well developed synapses were not observed. Among the various neuronal features displayed by the tumor cells, notably some extensive Nissl arrays and numerous subsurface cisternae, several were indicative of maturing nerve cells: branching tumoral processes provided with typical growth cones and dense cored “neurosecretory” vesicles. These vesicles are now considered to be one of the characteristics of newly developing nerve fibers. The presence of these developmental features in a nerve cell tumor helps to substantiate the embryonic origin of neuroblastomas postulated as arising from immature forms and not from dedifferentiated cells.
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  • 14
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 16 (1974), S. 93-107 
    ISSN: 1432-0827
    Keywords: Dentinogenesis ; Globules ; Pyrophosphatase ; Calcification ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract Three-day-old rats were fixed by perfusion with glutaraldehyde and thin slices were cut of the first molar germs. The slices were treated with EDTA and “activated” with buffered solutions containing Mg2+, Ca2+ or Zn2+. Incubation was carried out in buffered solutions (pH 8.5) containing inorganic pyrophosphate and Pb2+. In the Mg2+-activated specimens incubation products were localized to the plasma membranes in the stratum intermedium and the subodontoblastic area. Lead deposits were found on the periphery of the dentinal globules. Incubation products were more randomly distributed in Ca2+-activated specimens whereas those activated with Zn2+ displayed a deposition of lead precipitates mainly corresponding to that seen after activation with Mg2+. The findings are discussed in reference to the localization of alkaline phosphatase in the dentin-producing tissues and it is proposed that the results are indicative of the presence of an inorganic pyrophosphatase in these tissues.
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  • 15
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 14 (1974), S. 3-14 
    ISSN: 1432-0827
    Keywords: Hydroxyapatite ; Mineral ; Phase ; Chemistry ; Synthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Des diagrammes de phase d'équilibre ont été déterminés pour le système CaO-P2O5-H2O en utilisant des techniques de synthèse hydrothermique au cours de variatio nsde température allant de 300–600° et 2 Kb H2O de pression. De l'hydroxyapatite bien cristallisé a été synthétisé et caractérisé. De faibles variations de paramètres de la maille cristalline, liées à la température de synthèse et composition globale du matériel initial, ont été déterminées. Des conditions chimiques précises sont nécessaires pour obtenir de l'apatite, en tant que seule phase solide en équilibre dans la solution. Les résultats de diagramme de phase d'équilibre sont comparés avec ceux obtenus dans des milieux synthétiques.
    Abstract: Zusammenfassung Es wurden Gleichgewichts-Phasendiagramme für das System CaO-P2O5-H2O bestimmt, indem hydrothermale Synthese-Techniken im Temperaturbereich von 300–600° und bei einem Druck von 2 Kb H2O verwendet wurden. Es wurde gut-kristallisiertes Hydroxyapatit erzeugt und charakterisiert. Es wurden geringe Unterschiede in den Parametern der Zelleinheiten festgestellt, welche von der angewandten Temperatur und der Zusammensetzung des Startmaterials abhingen. Es waren genaue chemische Bedingungen nötig, um Apatit als die einzige feste Phase im Gleichgewicht mit der Lösung zu erhalten. Die Resultate der Gleichgewichts-Phasendiagramme werden mit früheren Untersuchungen mit der Synthesetechnik verglichen.
    Notes: Abstract Equilibrium phase diagrams have been determined for the system CaO-P2O5-H2 using hydrothermal synthesis techniques in the temperature range 300–600° and 2 Kb H2O pressure. Well-crystallized hydroxyapatite has been produced and characterized. Small variations in unit cell parameters dependent on temperature of synthesis and bulk composition of the starting materials have been determined. Precise chemical conditions were required to obtain apatite as the only solid phase in equilibrium with solution. Equilibrium phase diagram results are compared with previous synthetic investigations.
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  • 16
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 15 (1974), S. 213-220 
    ISSN: 1432-0827
    Keywords: Acid phosphatase ; Electron microscopy ; Shell Regeneration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract Acid phosphatase activity was mainly localized in the lysosomes in all the regions of the outer epithelium. The transitional portion of the outer epithelium showed more intense activity than the other regions. During shell regeneration the activity of this portion decreased to a minimum level at 12 hours and was restored to normal at 72 hours. The other regions showed no change of activity during shell regeneration. It is postulated that the acid phosphatase in the transitional protion is responsible for conferring calcifiability to the organic matrix of the shell.
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  • 17
    ISSN: 1573-0832
    Keywords: Microsporon audouinii ; Pyrrolnitrin ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Scanning and transmission electron microscopy showed that a ceiling quantity (1.56 mcg) of antifungal antibiotic Pyrrolnitrin caused heavy damage to dermathophyteMicrosporon audouinii Gruby CBS 313-54in vitro. Suitable preparation technique made it clear that the changes involved consisted of hyphal collapse on the edge of the culture, with loss of euplasmic organelles identity and cell autolysis. The cell wall, however, was apparently undamaged. These findings fit in with the suggestion that the mode of action of the antibiotic leads to generalised lipoproteic membranes damage. They must, however, be considered as representing the result of the terminal phase of cell distress.
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  • 18
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    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 20 (1974), S. 974-980 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Through the statement of the Ergun equation in a vectorial form, a formulation is presented for three-dimensional flow of fluids through packed beds having a spatially variable resistance to flow. The equations were put in a form convenient for numerical solution by successive over-relaxation, and a selection of computed results is presented for cylindrical beds where the nonuniform resistance to flow obeys axial symmetry. The method outlined in the paper for calculating flow maldistribution in packed beds is thought to be a necessary first step in the representation of hot spot formation and flow nonuniformities in packed bed reactors.
    Additional Material: 6 Ill.
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  • 19
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    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 20 (1974), S. 981-988 
    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 linear stability of thermally stratified horizontal two-phase Couette flow is analyzed for the case of a constant vertical temperature gradient. Instabilities driven by buoyancy, surface tension gradients, or shear are allowed for. It is shown that the instability can take three possible forms: streamwise oriented roll vortices, long interfacial waves, and short Tollmien-Schlichting waves. It is shown that the stability limits for rolls are identical to those for plane, stagnant layers. A long wave expansion is presented and the stability limits for this mode are given algebraically. The nonexistence of a Squire's Theorem is demonstrated and some numerical experiments at moderate Reynolds numbers are described. Detailed comparisons with previous work are possible for only one fluid pair, but it is shown that reasonably accurate statements may be made to determine which mode may manifest itself in any given experimental situation.
    Additional Material: 1 Ill.
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  • 20
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    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 20 (1974), S. 989-995 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Extensive ternary ion-exchange rate data for cases where particle-diffusion is important are presented. Experimental rate data, using a single-particle radioactive-tracer technique, were obtained for the following systems in Dowex 50W-X8 resin: Mn-Cs-Na, Ba-Mn-Na, and Sr-Mn-Cs. Nernst-Planck equations have been used to describe the ternary ion-exchange kinetics. The Nernst-Planck model, when used for the correlation of binary and various types of ternary exchange data obtained under unfavorable equilibrium conditions, usually cannot afford to disregard liquid-film resistance. The model incorporating the film effects correlated satisfactorily most of the experimental data, and even in cases where the correlation was not good, it interpreted adequately the trend of the results.
    Additional Material: 11 Ill.
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  • 21
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    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 20 (1974), S. 1010-1011 
    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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  • 22
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    AIChE Journal 20 (1974), S. 959-966 
    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 rate of secondary nucleation of ice, assumed to be proportional to the product of collision frequency and impact energy, has been quantitatively modeled using idealized representations of collisions between crystals and either other crystals or surfaces in the crystallizer. The crystal-crystallizer collisions were assumed to be driven by either steady or turbulent fluid motion and the crystal-crystal collisions were assumed to be driven by either gravitational forces or turbulent eddies. The models predict to a good approximation the experimentally determined dependence of the secondary nucleation of ice on crystal size, ice concentration, and agitation power.
    Additional Material: 6 Ill.
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  • 23
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    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 20 (1974), S. 1037-1037 
    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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  • 24
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    AIChE Journal 20 (1974), S. 1040-1040 
    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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  • 25
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    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 20 (1974) 
    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 20 (1974), S. 1017-1020 
    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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  • 27
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    AIChE Journal 20 (1974), S. 1020-1022 
    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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  • 28
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    AIChE Journal 20 (1974), S. 1027-1027 
    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 20 (1974), S. 1031-1034 
    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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  • 30
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    AIChE Journal 20 (1974), S. 1034-1036 
    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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  • 31
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    AIChE Journal 20 (1974), S. 1038-1040 
    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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  • 32
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    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Criteria are derived to specify the limit of stability for pure material and multicomponent thermodynamic systems. Through the use of Legendre transforms, the criteria may be expressed in a very simple form that only involves the determination of positiveness of a single second-order partial derivative of a potential function. Alternate and equivalent criteria are shown to result from a simple reordering of the independent variables in the Fundamental Equation of Gibbs. Certain criteria that are often stated as necessary conditions of stability (for example, Cv 〉 0) are shown to be insufficient for specifying the limit of stability; that is, a system will always become unstable for other reasons before Cb can attain a negative value.
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  • 33
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    AIChE Journal 20 (1974), S. 1219-1221 
    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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  • 34
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    AIChE Journal 20 (1974), S. 1218-1219 
    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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  • 35
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    AIChE Journal 20 (1974), S. 1234-1235 
    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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  • 36
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    AIChE Journal 20 (1974), S. 1236-1236 
    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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  • 37
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    AIChE Journal 20 (1974), S. 50-59 
    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 behavior of an immobilized enzyme reactor utilizing asymmetric hollow fibers is simulated using a theoretical model. In this reactor, an enzyme solution contained within the annular open-cell porous support structure of the fiber is separated from a substrate flowing through the fiber lumen by an ultrathin dense membrane impermeable to enzyme but permeable to substrate and product. The coupled set of model equations describing the behavior of this reactor represents an extended Graetz problem in the fiber lumen, with diffusion through the ultrathin fiber skin and reaction in the microporous sponge region. Exact analytic expressions for substrate concentration profiles throughout an idealized fiber which incorporate the membrane and hydrodynamic mass transfer resistances are obtained for a first-order enzyme reaction, and numerical techniques for their evaluation are given. This analysis is extended to yield a numerical finite difference solution for nonlinear Michaelis-Menten reaction kinetics, which is shown to agree with the analytic solution, as Km/C0, the ratio of the Michaelis constant to the initial substrate concentration, becomes large (〉 100).
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  • 38
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    AIChE Journal 20 (1974), S. 94-103 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Temperature and concentration profiles are obtained by solution of the coupled nonlinear differential equations which describe transient operation of an adiabatic fixed bed reactor. The unreacted-shrinking core mechanism describes the multiple, irreversible, exothermic gas-solid reactions. Numerical integration is accomplished by a predictor-corrector scheme which is programmed in Fortran IV language. The influence of kinetic parameters, heat and mass diffusivities within pellets, temperature variation of properties, gas velocity, bed and particle dimensions, inlet gas temperature and composition, and initial bed temperature on reactor performance are studied for sulfur dioxide removal from flue gases by fixed beds of copper oxide. Comparison with commercial reactors is in qualitative agreement.
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  • 39
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    AIChE Journal 20 (1974), S. 118-127 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A general structure is proposed for determining a set of long-term (multi-year) source control measures which achieve specified levels of air quality for an airshed at least cost. Such a structure is useful in evaluating alternative air pollution abatement strategies from the standpoint of air quality and total cost. The theory is applied to the problem of evaluating sets of control actions over the period 1973-1975 in Los Angeles. Costs of achieving various levels of air quality in Los Angeles over this period are determined.
    Additional Material: 2 Ill.
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  • 40
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    AIChE Journal 20 (1974), S. 109-118 
    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 three-parameter correlation of Pitzer et al. for fugacity coefficients (f/P) has been extended to liquids in the 0.5 ≤ Tr ≤ 0.8 and 0.2 ≤ Pr ≤ 9.0 region. In addition, values of the derivative compressibility factors ZT and ZP have also been obtained in the same region. This extension is based on the generalized correlation of the compressibility factor Z recently reported. The isothermal coefficient of bulk compressibility βT compiled by Rowlinson has been employed with the pressure effect on βT taken into consideration. The correlation for f/P obtained in this work is compared with that of Curl and Pitzer at Tr = 0.8, Chao et al. at Tr from 0.50 to 0.70, and that of Carruth and Kobayashi in the 0.50 ≤ Tr ≤ 0.64 region. Using the tabulated ZP and ZT values \documentclass{article}\pagestyle{empty}\begin{document}$ \frac{{H^* - H}}{{T_c }},{\rm }\left ({\frac{{\partial V}}{{\partial P}}} \right)_T $\end{document}, and \documentclass{article}\pagestyle{empty}\begin{document}$ \left ({\frac{{\partial V}}{{\partial T}}} \right)_P $\end{document} have been calculated and compared satisfactorily with the corresponding values derived from literature data. In addition, a correlation of vapor pressures of both hydrocarbons and nonhydrocarbons is also presented. The agreement between this correlation and those reported by Pitzer et al. and Carruth and Kobayashi is very satisfactory.
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  • 41
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    AIChE Journal 20 (1974), S. 133-140 
    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 simple algorithm for the time-optimal control of chemical processes during setpoint changes, in processes which can be described by a second-order lag plus dead time model, is described. Knowledge of the unsteady state model parameters is not required because the algorithm uses a dimensionless phase plane on which the switching curves are independent of system parameters for a given forcing function. The algorithm gives the parameters of a second-order lag plus dead time model as a by product of the setpoint change. It is easily tuned and is relatively insensitive to changes in the process dynamics. The algorithm does not require a large computer or long computing times and has been implemented on both analog and digital computers in controlling computer simulated systems.
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  • 42
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    AIChE Journal 20 (1974), S. 141-147 
    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 is a study of a photochemical reactor consisting of a vortex-stabilized arc and an annular, triple-walled, fused silica reaction chamber. An argon arc plasma provides the light. For power inputs of 3-12 kw, the spectral output of the light source was characterized as a function of wavelength, arc-gas flow rate, power input to the arc, and position along the arc. For power inputs of 3.84 and 8.45 kw, there were, respectively, 0.314 and 0.862 einsteins emitted per hour in the 2500 to 5000Å wavelength region. Selective filter solutions of 1.5N KNO3 and 0.05N KI were investigated. A reactor analysis is presented, based on mass and energy balances, and the geometrical properties of the system.
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  • 43
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    AIChE Journal 20 (1974), S. 148-154 
    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 photochemical chlorination of sulfur dioxide was investigated experimentally. The photochemical reactor was the vortex-stabilized arc radiation source described in Part I. Aqueous inorganic solutions, providing selective wavelength filtration, were circulated through the inner annular region. The outer annulus served as the reaction volume. The dependence of the reaction on wavelength, reaction gas inlet temperature, pressure, and reactant flow rate was investigated. The amount of sulfur dioxide in the mixture was varied from 1/6 to 2/3 atmosphere. The photochemical rate of formation of sulfuryl chloride is best described by the rate expression: \documentclass{article}\pagestyle{empty}\begin{document}$$ r = J - k_0 \exp \left[{ - \frac{E}{{RT}}\sqrt {J/\left ({{\rm SO}_2 } \right)} } \right]{\rm } \cdot \left ({{\rm SO}_{\rm 2} {\rm Cl}_{\rm 2} } \right) $$\end{document} where J is the volumetric rate of light absorption and where k0 and E have values of 0.0542 s1/2 and -2.6 kcal/gmol, respectively.
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  • 44
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    AIChE Journal 20 (1974), S. 154-158 
    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 steady, laminar, isothermal flow of non-Newtonian fluids in the entrance region of an annulus has been studied experimentally. The axial pressure distributions, as well as the excess pressure energy, in the developing flow region are presented. The loss coefficients are found to increase with increasing flow behavior index for inelastic power law fluids. The experimental values of the loss coefficients are about 20% lower than those predicted from the boundary-layer approximation method presented earlier. A preliminary result indicates that the entrance loss for a viscoelastic fluid is much smaller than that for the inelastic fluid of the same flow behavior index.
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  • 45
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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: The effect of changing platinum crystallite size from 2.7 to 15.5 nm on the specific catalytic activity in NO reduction by NH3, with and without added O2, was studied over alumina supported platinum catalysts between 423 and 473°K. In the NO-NH3 system both specific catalytic activity and selectivity to N2 are independent of crystallite size. In the NO-O2-NH3 system the specific catalytic activity of the 15.5 nm crystallites is about six times that of the 2.7 nm crystallites. The NO reduction rate shows dependence on NO to the first power and on NH3 to the one-half power.
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  • 46
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    AIChE Journal 20 (1974), S. 306-310 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A thermal continuous parametric pump for separating multicomponent mixtures was experimentally investigated using the model system tolueneaniline-n-heptane on silica gel adsorbent. A simple method for predicting separations is presented and is found to be in good agreement with the experimental results. The method, based on an equilibrium theory, invokes the assumption that a multicomponent mixture contains a series of pseudo binary systems. Each binary system consists of one of the solutes as one component and the common inert solvent as the other component.
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  • 47
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    AIChE Journal 20 (1974), S. 311-319 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Since operation error is a major factor contributing to industrial disaster, it is necessary to develop safety interlock systems which prevent modes of operation that are known to be dangerous. It is not possible to foresee all the disruptions that might occur and, for this reason, an a priori analysis of safety problems is incomplete. At each step in operation the state of the process must be updated if hazardous conditions are to be avoided. To a large extent this is a problem in logic which can be handled rapidly by the computer using the methods developed here.
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  • 48
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    AIChE Journal 20 (1974), S. 402-404 
    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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  • 49
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    AIChE Journal 20 (1974), S. 404-407 
    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: 4 Ill.
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  • 50
    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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    AIChE Journal 20 (1974), S. 410-412 
    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: 4 Ill.
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    AIChE Journal 20 (1974), S. 413-413 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
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    AIChE Journal 20 (1974), S. 414-415 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
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    AIChE Journal 20 (1974), S. 415-416 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
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    AIChE Journal 20 (1974) 
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    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
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    AIChE Journal 20 (1974), S. 416-416 
    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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    AIChE Journal 20 (1974), S. 445-453 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Procedures are developed for predicting liquid film controlled mass transfer in gas sparged contactors with and without mechanical agitation. Mass transfer is shown to depend on mean bubble size. Bubble shape, motion, and interface fluctuations are all properties that are associated with bubble size, which, in turn, can be determined from the physical characteristics of the contacting system.Experimental measurements were made on CO2 stripping from aqueous solution with air in 0.00252, 0.0252, and 0.252 m3 tanks. The vessels were geometrically similar, fully baffled, and equipped with four flat-blade impellers and spargers. These measurements are used to evaluate earlier correlations and to develop improved scale-up procedures.
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  • 58
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    AIChE Journal 20 (1974), S. 454-461 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Turbulent pipe flow was examined by measuring the radial dispersion of dyed fluid introduced at an axial point source within the flow. From the classical theoretical results of G. I. Taylor it was possible thereby to calculate various parameters that characterize the structure of the turbulent flow field. A comparison was made between water, and aqueous solutions of polyethylene oxide (Polyox) at concentrations up to 50 ppm (by weight). Results indicate that Polyox affects the turbulence in the following ways: (1) intensity is reduced, (2) the energy spectrum is shifted toward low frequency, (3) dispersion occurs largely through large scale motion, and intermittency is increased. Indication is also seen that a simple exponential form for the Lagrangian correlation coefficient is superior to other often recommended models.
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  • 59
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    AIChE Journal 20 (1974), S. 467-474 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Nucleation and crystal growth processes involved in the batch precipitation of photographic emulsions by the addition of silver nitrate to an aqueous solution of bromide and gelatin have been reasonably successfully modeled. Simulation predicts the known increase in average crystal size with increased addition time, with increased temperature, and with increased halide levels. Solubility is related to crystal size by the Gibbs-Thomson equation. The predicted decrease in the number of crystals during the course of precipitation is similar to published data, but there are quantitative differences. The model is very sensitive to variations in the constant in the growth equation, but not to variations in the constants in the nucleation equation.
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  • 60
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    AIChE Journal 20 (1974), S. 474-484 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Theoretical investigations of viscous heating in the flow of fluids with an exponential dependence of viscosity on temperature have shown that, for a given shear stress, two shear rates are possible. Above a critical value, the stress decreases as the shear rate increases.The present work is an experimental study of this phenomenon in plane and circular Couette flows and in cylindrical Poiseuille flow. ArochlorR 1260, a high viscosity Newtonian fluid with an extremely sensitive viscosity-temperature dependence is used as the test fluid. The results clearly show that two shear rates for Couette flow exist for one measured wall shear stress. Because of the viscosity-pressure dependence of the fluid, the Poiseuille flow results are inconclusive.
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  • 61
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    AIChE Journal 20 (1974), S. 485-491 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: When ultrasound is applied to a liquid reacting system, the reaction rates are often increased. The application of ultrasonics, therefore, provides additional modes of accelerating the reaction rates which are usually not considered by conventional mechanisms. In an attempt to study the effect of ultrasonics on chemical reactions, experimental work was undertaken in which the reaction rates of the hydrolysis of methyl acetate were measured under the presence of ultrasound. The temperature, the vapor pressure with in the cavitating bubbles, the resonance characteristics, the volume of the reacting system, and the intensity and frequency of the ultrasound are all influencing parameters on the reaction rates.
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  • 62
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    AIChE Journal 20 (1974), S. 564-570 
    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 refractive index matching technique has been developed to study the behavior and coalescence phenomena of drops in closely packed dispersion bands. The frequency of drop-drop coalescence has been measured and correlated, and a mathematical model, based on film rupture thickness, has been written for solution by computer to predict dispersion band thickness as a function of inlet drop size, flow rate, and the physical properties of the system.
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  • 63
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    AIChE Journal 20 (1974), S. 619-620 
    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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  • 64
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  • 65
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    AIChE Journal 20 (1974), S. 622-622 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 66
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    AIChE Journal 20 (1974), S. 622-623 
    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 20 (1974) 
    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 20 (1974), S. 707-712 
    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 optimal temperature policy which will maximize the final catalyst activity that gives a fixed conversion of reactants in a specified time for batch operation was determined by the formulation of a calculus of variations problem following the technique of Szepé and Levenspiel (1968). The method was applied to the general case of first-order reversible reactions which occur in the presence of catalysts deactivating by an irreversible first-order mechanism. To reduce trial and error estimations and circumvent numerical instabilities, the two-point boundary value variational problem was reformulated in terms of an initial value problem with a parameter which includes the initial value of temperature. This initial value problem was solved by a regression technique.These techniques were applied to the industrially important enzymatic reaction of the isomerization of D-glucose to D-fructose catalyzed by glucose isomerase in solution. Kinetic and deactivation data are available for this endothermic reaction which obeys first-order reversible kinetics and for the isomerase denaturation which appears to be first order. The optimal temperature operational policy as stated above maximized final enzyme activity such that 10% less denaturation of glucose isomerase occurred when compared to final isomerase activity yielding the same conversion for the same reaction time when the reactor is operated at the optimal isothermal temperature.
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  • 69
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    AIChE Journal 20 (1974), S. 720-727 
    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 rate constants appearing in differential equations derived from proposed mechanisms for methane pyrolysis were estimated from published integral conversion data. Quasilinearization, capable of fitting the differential equation solutions directly to the integral data and therefore not requiring differentiation or transformations, was used. Since differential equations representing free radical reactions have coefficients varying over many orders of magnitude, implicit numerical integration was used to obtain the numerous particular and homogeneous solutions required in the execution of the algorithm. Convergence was achieved by replacing the concentrations after each iteration with values near the solution at that point and by repeatedly estimating a small number of parameters in a cyclic manner in order to improve starting estimates of all parameters simultaneously. The mechanisms attempted were considered plausible when they led to adequate data fits and reasonable rate constant estimates. The major contribution of the work is that the algorithm is capable of testing a mechanistic model over a relatively wide range of conditions with minimal experimental data.
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  • 70
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    AIChE Journal 20 (1974), S. 728-734 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Adsorption rate data were measured at 25° to 75°C for benzaldehyde on polymeric, porous Amberlite particles. When the benzaldehyde is dissolved in methanol, the adsorption capacity is very low. Data for methanol solutions gave reasonable values for intraparticle diffusivities based solely on transport in the pore volume. For adsorption from aqueous solution (where the adsorption capacity was high), the contribution of surface diffusion was important.From the two sets of data it was possible to evaluate average effective surface diffusivities by using a model based upon both pore-volume and surface transport. These values were about 10-8 cm2/s and were sufficiently sensitive to temperature to give activation energies of 7 to 9 k cal/mole.For the more hydrophobic Amberlite, XAD-4, surface transport was many times as large as pore-volume diffusion.
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  • 71
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    AIChE Journal 20 (1974), S. 742-750 
    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 applies the principles of geometric programming to the optimization of the well-known Williams-Otto process. Following the trend of the articles published on this subject, two different objective functions are considered and the results are compared to those of other investigators.The dual geometric program is used to provide an answer to the question of why the optimal value of the objective function remains unchanged for perturbations in a certain variable.
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  • 72
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    AIChE Journal 20 (1974), S. 735-742 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: By means of infrared internal reflection spectroscopy we measured the time dependence of the surface concentration of stearic acid molecules over a well defined region of the surface. The molecules were diffusing into this region from a source comprising a compressed monolayer or bulk crystalline material outside the field of view. By these measurements in conjunction with solutions to the diffusion equations we determined the diffusion coefficient Ds of stearic acid on the (0001) plane of α-alumina. We also determined the dependence of Ds upon the amount of water coadsorbed on the surface. When the surface was free of reversibly adsorbed water, Ds had a value of about 2 × 10-7 cm2/s. As the surface coverage of coadsorbed water increased to about a monolayer Ds increased to a maximum value of about 4 × 10-5 cm2/s. With further additions of surface water Ds then decreased and became less than 10-8 cm2/s at coverages slightly less than about two monolayers. In the region of its maximum value the temperature dependence of Ds indicated an activation energy for the diffusion process of about 26 kcal/mole.
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  • 73
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    AIChE Journal 20 (1974), S. 751-761 
    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 desalination performance of a tubular reverse osmosis membrane was studied under well-defined hydrodynamic conditions. Experimental measurements were made of local mass transfer rates in a 2.31-cm I.D. × 81-cm long horizontal cellulose acetate membrane at 16 locations along the tube length for both laminar and turbulent flows. The membrane's intrinsic permeability to water and NaCl was found to vary significantly along its productive length.The experiments suggest that the dominant transport mechanisms in laminar flow are forced convection in the upstream region and combined free and forced convection in the downstream region, beyond a distance of approximately 16 tube diameters, for all feed concentrations studied. The Deissler analogy applies well to the turbulent region for Re ≧ 104; however, it increasingly overpredicts performance as Re is decreased below 104.The experimental results of other workers are interpreted successfully in terms of the mechanisms deduced in the present work.
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  • 74
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    AIChE Journal 20 (1974), S. 776-784 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: It is suggested that chromatographic separations can be performed very effectively in the absence of a stationary sorbent phase by using small diameter tubes or tube bundles for the column and segregating the solutes radially into the slower moving fluid near the tube walls. Separation is achieved by differential solute retardation whenever the degree of segregation is different for the various solute species present.An approximate analysis and preliminary experimental studies demonstrate the feasibility of using ultrafiltration through the tube wall to achieve solute separation. Preliminary estimates based on our ultrafiltration analysis also show that segregation by electromigration is very promising for electrically charged solutes.
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  • 75
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    AIChE Journal 20 (1974), S. 785-795 
    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 flow of polymer melts in cylindrical, annular, and slit dies has been examined. Large temperature rises at the outer surface of the extrudate were measured with an infrared pyrometer. Calculations show that severe radial temperature gradients exist in these flow geometries under conditions similar to those encontered in polymer processing and in viscometry measurements. A common method of estimating the average temperature rise from the total mechanical energy input seriously underestimates the maximum temperature rise.A numerical solution of the flow and energy equations models the flow in all three geometries. A very simple Nusselt number correlation allowed an estimate of the temperature rises possible if heat transfer with the die wall occurrs. Good agreement was obtained between predicted and infrared measured melt surface temperature rises. The pressure drop gives only an indication that nonisothermal flow is occuring and is not sensitive enough to distinguish the type of heat transfer boundary condition present.The mathematical model presented could be helpful in die design and in process modeling, allowing the designer to obtain some knowledge of the kind of flow situations which might be encountered.
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  • 76
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    AIChE Journal 20 (1974), S. 795-803 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Ice-crystal secondary nucleation kinetics are derived from thermal response experiments carried out with concentrated sugar solutions and fruit juices. Variables studied include the level of supersaturation, power input, sugar concentration, sugar type, and the presence of high-molecular-weight additives. The nucleation rate is indicated to have a low-order dependence upon subcooling (about 1.25 power) for subcoolings in the range 0.25 to 1.00°C. Fruit juices are well modeled by the corresponding synthetic sugar solution. The selection and improvement of processing approaches for freeze concentration of food liquids are discussed in light of the experimental results.
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  • 77
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    AIChE Journal 20 (1974), S. 803-814 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Adiabatic Joule-Thomson coefficients are presented for argon and two argon-carbon dioxide mixtures (46.4% CO2 and 75.4% CO2) in the single-phase part of the range: -120 〈 T 〈110°C, P 〈 190 atm. Results are analyzed in terms of the virial equation (including terms to account for the quadrupole moment of CO2), several forms of the Redlich-Kwong equation, and the Benedict-Webb-Rubin equation. In general, the best results were obtained by the Redlich-Kwong equation as modified by Barner et al. (1966).
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    AIChE Journal 20 (1974), S. 815-816 
    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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  • 79
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    AIChE Journal 20 (1974), S. 819-820 
    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 Tab.
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  • 80
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    AIChE Journal 20 (1974), S. 820-822 
    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: 4 Ill.
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  • 81
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    AIChE Journal 20 (1974), S. 817-818 
    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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  • 82
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    AIChE Journal 20 (1974), S. 847-855 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: It is demonstrated that a single equation of state may be used to describe all three phases in liquid-liquid-vapor equilibrium situations. Wilson's version of the Redlich-Kwong equation is shown to predict accurately the water solubility in normal paraffins with interaction parameters k12 = 0.50. A simple procedure for three-phase flash computations is presented. Results obtained using this procedure for the system methane, n-butane, water exhibit many of the characteristics of the experimental data of McKetta and Katz (1948). In particular, the water content of the vapor phase and the liquid hydrocarbon phase are accurately predicted.
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    AIChE Journal 20 (1974), S. 863-872 
    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 instability and breakup of laminar liquid jets in gaseous surroundings is investigated for conditions under which a solute is transferring across the jet interface rendering the system susceptible to Marangoni convection. Linear hydrodynamic stability analysis reveals that solute transfer out of the jet is stabilizing (produces longer jets) while transfer into the jet is destabilizing and promotes breakup. Solute adsorption, including as a limiting case the presence of a spread surfactant monolayer, may strongly counteract the stabilizing or destabilizing effects of mass transfer but has only a negligible effect on jet stability in the absence of interphase mass transfer. Qualitative experimental results for water jets in air with acetone as the transferring solute corroborate both the stabilizing and destabilizing mass transfer effects predicted by the theory.
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    AIChE Journal 20 (1974), S. 872-880 
    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 instability and breakup of laminar liquid jets in liquid surroundings is investigated for situations where solute transfer across the jet interface renders the system susceptible to Marangoni convection. This work parallels Part I (Burkholder and Berg, 1974) on the effect of mass transfer on the breakup of laminar liquid jets in gases. Behavior in liquid-liquid systems, however, differs significantly from that for liquid-gas systems and cannot be inferred from the analysis of the latter. Linear hydrodynamic stability analysis reveals that transfer either into or out of the jet may be either stabilizing (longer jets) or destabilizing depending on system physical properties and mass transfer rate. Solute adsorption may strongly counteract the effects of the mass transfer but has only a small effect on jet stability in the absence of mass transfer. The predicted mass transfer effects conform qualitatively to the experimental results of Meister and Scheele (1969) for acetone transfer between benzene jets and water.
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    AIChE Journal 20 (1974), S. 950-958 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Experiments were designed to identify the mechanism of the secondary nucleation of ice in a vigorously agitated crystallizer. It has been shown that the nucleation rate is proportional to the product of two factors, one characterizing crystal morphology and the other the rate of removal of potential nuclei from the surfaces of the existing crystals. Consequently, the nucleation rate attributable to different mechanisms is additive and the rate is proportional to the number of collisions per crystal. The contribution to the secondary nucleation of ice, by collisions of crystals with the impeller, baffles, and other crystals in an agitated crystallizer have been identified by measurements in a batch crystallizer in which each of the different collision mechanisms could be suppressed.
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    AIChE Journal 20 (1974), S. 966-974 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: With a Mach-Zehnder interferometer, salt concentration profiles were measured in a reverse osmosis system under natural convection with the membrane in a vertical position. The measured concentration profiles compared favorably with those predicted theoretically as long as the motion remained laminar. At large distances from the leading edge, however, the flow developed a wavy pattern, especially for bulk salt concentrations in excess of 0.1 moles/liter. As expected, whenever this motion became especially pronounced, the concentration of salt at the membrane surface was less and the production rate of fresh water greater than that predicted using the laminar analysis.
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  • 87
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    Additional Material: 3 Ill.
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  • 88
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    AIChE Journal 20 (1974), S. 1003-1009 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Extensive gas phase dispersion data are reported for extremely high liquid-gas ratios in a cylindrical packed absorption tower operated at atmospheric pressure under counterflow conditions.The dispersion data report gas Peclet numbers in terms of superficial liquid and gas Reynolds numbers over the range \documentclass{article}\pagestyle{empty}\begin{document}$$ \begin{array}{*{20}c} 0 & 〈 & {N{\mathop{\rm Re}\nolimits} _{\rm L} } & 〈 & {1500} \\ {15.0} & 〈 & {N{\mathop{\rm Re}\nolimits} _{\rm S} } & 〈 & {500} \\ \end{array} $$\end{document}An increase in Peclet number with increasing gas rate is observed at subloading conditions.Reverse gas flow was observed in the gas phase when the liquid Reynolds number exceeded 650. Dispersion in the gas phase at liquid rates for which NReL 〈 650 is consistent with previously recorded correlations but becomes independent of further increases of liquid rate when NReL is 〉 650.The dispersion coefficients obtained by dynamic testing under reverse gas flow conditions were consistent with those obtained from steady state absorption profiles and provide a quantitative explanation for the anomalies in plug-flow KLa at high water rates recorded by Sherwood and Holloway (1940).
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    AIChE Journal 20 (1974), S. 1178-1187 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Rates of deposition of particles onto a spherical collector, immersed in a creeping fluid, are calculated as a function of Peclet number, aspect ratio, and the ratio of Hamaker's constant to kT for all cases of practical importance involving convective-diffusion and London forces. Boundaries of regions where London forces or Brownian motion may be neglected are established in terms of the above dimensionless groups. Gravitational forces were included in the calculations for some representative conditions but may be neglected for small or neutrally buoyant particles or for high flow rates.Close agreement was noted between deposition rates calculated by summing individual contributions from each transport mechanism and deposition rates calculated from a rigorous consideration of their combined effect. Thus the additivity rule was verified for the cases studied.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 90
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    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 20 (1974), S. 1041-1066 
    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 survey is given of co-rotational rheological equations suitable for describing the flow of viscoelastic liquids such as polymer solutions and melts. Comparisons are given with experimental data and molecular theories. An introduction to kinematical descriptions in co-rotating reference frames is included.
    Additional Material: 21 Ill.
    Type of Medium: Electronic Resource
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  • 91
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 20 (1974), S. 1079-1086 
    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 challenging problem in liquid-gas, interfacial phenomena is the prediction of the size and location of a flowing meniscus because it involves surfaces which are highly curved. The paper presents one aspect of this problem. A numerical method is presented for predicting the dynamic meniscus profiles-specifically these distorted considerably by flow. The geometry considered to provide those free (liquid-gas) surfaces is coating of a moving sheet by upward withdrawal from a finite bath. The predicted profiles agree with data taken with a glycerine-water solution and with viscous oils.The method predicts the three parameters (coating thickness and two others) which are the minimum number of parameters necessary to describe the dynamic-meniscus profiles for this geometry. The numerical method is iterative, it simultaneously predicts the flow field in the bath, and it is based on the two-dimensional Navier-Stokes equations and appropriate boundary conditions. The interfacial boundary condition used for iteration is the normal stress condition which is composed of pressure, surface tension, and viscous terms.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 92
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 20 (1974), S. 1110-1117 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Surface diffusivities of benzaldehyde in liquid-filled pores of Amberlite particles (polystyrene) were measured at 25°C using water as a solvent. For particles of different surface areas but chemically similar pore surfaces, the intrinsic surface diffusivity Ds' was about the same, but the relative importance of surface to pore-volume diffusion increased with surface area. For a single type of particle, the adsorption capacity was decreased about twenty-fold by adding up to 19 mole % methanol to the solvent. This was accompanied by an increase in Ds' from 1.2 × 10-8 to 1.2 × 10-7 cm2/s. These results were interpreted in terms of a two-step theory for surface migration: (1) formation of a vacant site on the adsorbent surface followed by (2) movement of the adsorbate molecule into the site by breaking the surface-adsorbate bond. The theory predicts that surface transport will be large when the surface area is high and that the Ds' will be large when the heat of adsorption is low, and when the bond between solvent molecules and the surface is weak.In our studies the surface contribution to intraparticle transport was as much as 20 times the contribution due to pore-volume diffusion. This ratio increases as the concentration of adsorbate in the liquid decreases.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 93
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 20 (1974), S. 1228-1231 
    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.
    Type of Medium: Electronic Resource
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  • 94
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    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 20 (1974), S. 1233-1233 
    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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  • 95
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 20 (1974), S. 1224-1226 
    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: 4 Ill.
    Type of Medium: Electronic Resource
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  • 96
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 20 (1974), S. 1154-1160 
    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 optimization method has been developed that searches one variable at a time under the conditions that previously searched variables are at their approximate optimum and variables to be searched later are constant. This method provides the optimum and also information on the effects of the variables. The method is based on the Partan and Powell methods and on assuming linear partial derivatives of the objective function with respect to any given variable. The procedure involves searching each variable separately with other variables either constant or varied so that they remain at their estimated optimum for the given conditions. This method provides useful information on the effects of independent variables as well as locating the overall optimum and a number of partial optimums and requires a comparable number of trials.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 97
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 20 (1974), S. 1235-1235 
    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
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 20 (1974), S. 1236-1246 
    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 Tab.
    Type of Medium: Electronic Resource
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  • 99
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 20 (1974), S. 128-133 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Both polymeric solutions and fiber suspensions have separately been known to exhibit drag reduction under turbulent flow conditions. It has recently been shown that the mechanisms of drag reduction differ appreciably in these two kinds of systems.The objective of this study was to show that both mechanisms may be exploited concomitantly to achieve unusually low friction factors. Drag reductions in excess of 95% have been obtained in a 2.4-cm tube and there is no evidence that even more dramatic results could not be obtained under optimal conditions.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
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  • 100
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 20 (1974), S. 159-166 
    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 class of algorithms for the suboptimal feedback control of parabolic systems is presented. Three specific techniques within this class are developed and tested numerically using a linear example with three different types of boundary conditions. Performance of two of these techniques is found to compare favorably with that obtained by use of a rigorous open-loop optimal control computed by the gradient method. It is also shown for linear systems having quadratic performance criteria that the new algorithms are superior to the technique presented by Vermeychuk and Lapidus (1973) in cases where state deviation has a weighting coefficient much greater than that for control energy.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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