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  • 1990-1994  (835)
  • 1991  (835)
  • Chemical Engineering  (643)
  • Genetics  (192)
  • 1
    Electronic Resource
    Electronic Resource
    Variation between strains of the flour beetle Tribolium castaneum in relative performance on five flours (1991)
    Springer
    Entomologia experimentalis et applicata 60 (1991), S. 173-182 
    Details
    ISSN: 1570-7458
    Keywords: Genetics ; evolution ; host adaptation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract When populations are exposed to different environments, evolutionary processes can lead either to genetically differentiated strains or to the appearance of increased generalism at the individual level. For evolution to occur, genetic variability in performance in different environments is required. Here, intraspecific genetic variation across environments was estimated in the flour beetle Tribolium castaneum (Herbst) by comparing the responses of two strains of T. castaneum to different flour types. Replicated groups from each strain were allowed to develop on either the standard whole wheat medium or on one of four novel flours (wheat, rice, corn and oat). In several of the novel flours, clear differences in mean development time or population size of one or both strains were seen relative to performance in the standard medium. Moreover, the strains differed significantly in their phenotypic responses to the flours. One strain did particularly poorly on oat flour. Reduced oviposition, reduced larval survivorship and increased larval cannibalism were examined as possible causes of the low productivity on oat flour. These three factors accounted for about 70% of the reduction in population size when this strain oviposited and developed in oat flour. The difference between these two outbred strains in response to these five flours suggests that genetic variation in resource use is present within T. castaneum and may also be present within strains and natural populations in grain storage facilities. Such variation would permit an evolutionary response to selection in multiple environments (flours). This process has agricultural implications when several types of grain are stored in a single location because it could eventually lead to the evolution of highly generalized populations of T. castaneum, an important pest of stored products.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00177038
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  • 2
    Electronic Resource
    Electronic Resource
    Molecular analysis of iron transport in plant growth-promotingPseudomonas putida WCS358 (1991)
    Springer
    BioMetals 4 (1991), S. 36-40 
    Details
    ISSN: 1572-8773
    Keywords: Iron transport ; Siderophores ; Pseudomonas putida ; Genetics ; Receptors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary Root-colonizingPseudomonas putida WCS358 enhances growth of potato in part by producing under iron-limiting conditions a yellow-green, fluorescent siderophore designated pseudobactin 358. This siderophore efficiently complexes iron(III) in the rhizosphere, making it less available to certain endemic microorganisms, including phytopathogens, thus inhibiting their growth. At least 15 genes distributed over five gene clusters are required for the biosynthesis of pseudobactin 358. High-affinity iron(III) transport in strain WCS358 is initiated by an 86-kDa outer membrane receptor protein (PupA) which appears to be specific for ferric pseudobactin 358. PupA shares strong similarity with TonB-dependent receptor proteins ofEscherichia coli, which suggests a TonB-like protein in strain WCS358 is required for iron(III) transport. Strain WCS358 possesses a second uptake system for ferric pseudobactin 358 and structurally diverse ferric siderophores produced by other microorganisms. A second receptor gene (pupB) responsible for iron transport from pseudobactin BN7 or pseudobactin BN8 has been identified. The production of this and certain other ferric siderophore receptor proteins requires that strain WCS358 be grown in the presence of these siderophores. An apparent regulatory gene required for the expression ofpupB is located adjacent topupB. Two positive regulatory genes have been identified which can independently activate, under low-iron(III) conditions, transcription of genes coding for the biosynthesis of pseudobactin 358.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01135555
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  • 3
    Electronic Resource
    Electronic Resource
    Immunoglobulin allotypes are not associated with HLA-antigens, autoantibodies and clinical symptoms in systemic lupus erythematosus (1991)
    Springer
    Rheumatology international 11 (1991), S. 179-182 
    Details
    ISSN: 1437-160X
    Keywords: Immunoglobulin allotypes ; Systemic lupus erythematosus ; Genetics ; Gm ; Km ; HLA-antigens ; Autoantibodies ; Clinical symptoms
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Immunoglobulin heavy chain (G1m, G2m, G3m, A2m) and kappa light chain (Km) allotype and phenotype frequencies of 323 central European Caucasian patients with systemic lupus erythematosus (SLE) were examined and correlated with various genetic, serologic and clinical markers of SLE. No significant associations were found between immunoglobulin allotypes or phenotypes and all 20 parameters tested (nephritis, vasculitis, arthralgias, photosensitivity, discoid lesions, central nervous system disease, Raynaud's phenomenon, sex, anti-Ro, anti-La, anti-nRNP, HLA-DR1-DR7, HLA phenotypes B8-DR3, B7-DR2). It could therefore be assumed that Gm, A2m and Km allotypes were not associated with HLA-antigens and had no influence on the serologic and clinical expression of SLE.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00332558
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  • 4
    Electronic Resource
    Electronic Resource
    Hemochromatosis and pyruvate kinase deficiency (1991)
    Springer
    Annals of hematology 62 (1991), S. 188-189 
    Details
    ISSN: 1432-0584
    Keywords: Hemochromatosis ; Pyruvate kinase deficiency ; Hereditary anemia ; Genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Hemochromatosis has been reported in several patients with chronic hemolytic anemia due to pyruvate kinase deficiency. We describe here a further patient with such an association and review the literature on the subject. We hypothesize that iron overload may occur in patients with pyruvate kinase deficiency who are also carriers of the hereditary hemochromatosis gene.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01703147
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  • 5
    Electronic Resource
    Electronic Resource
    Association between a restriction fragment length polymorphism at the liver/islet cell (GluT 2) glucose transporter and familial Type 2 (non-insulin-dependent) diabetes mellitus (1991)
    Springer
    Diabetologia 34 (1991), S. 734-736 
    Details
    ISSN: 1432-0428
    Keywords: Genetics ; diabetes mellitus ; restriction fragment length polymorphism ; glucose-transport ; familial
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Patients with Type 2 (non-insulin-dependent) diabetes mellitus and a strong family history of the disease may represent a sub-group where genetic factors play a pree-minent role in transmission of the disease. A defect in the liver/islet cell glucose transporter (GluT 2) could explain many of the pathophysiological features of the disease. In order to test the hypothesis that genetic variation at the GluT 2 locus contributes genetic susceptibility to Type 2 diabetes, 60 unrelated Caucasian diabetic patients with at least one affected sibling were genotyped for a Taq 1 restriction fragment length polymorphism marker. Hybridisation with a cDNA GluT 2 probe identified two alleles of sizes 13 kilobase (T1) and 19 kilobase (T2). The allele frequencies in the diabetic group with a family history were significantly different from those in a racially-matched control population of 122 subjects with no personal or family history of the disease (diabetic patients T1=0.96, T2=0.04, control subjects T1=0.89, T2=0.11, p〈 0.03). However, when the study was repeated with 54 diabetic patients with indeterminate family history, statistical significance was not reached although the allele frequencies showed a similar trend. The findings of this study support the hypothesis that a genetic variant of the liver/islet cell glucose transporter may contribute to familial susceptibility in Type 2 diabetes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00401519
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  • 6
    Electronic Resource
    Electronic Resource
    Shared genetic susceptibility of Type 1 (insulin-dependent) and Type 2 (non-insulin-dependent) diabetes mellitus: contributions of HLA and haptoglobin (1991)
    Springer
    Diabetologia 34 (1991), S. 350-355 
    Details
    ISSN: 1432-0428
    Keywords: Genetics ; Type 1 (insulin-dependent) diabetes mellitus ; Type 2 (non-insulin-dependent) diabetes mellitus ; HLA ; haptoglobin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Epidemiologic data suggest that having a parent with Type 2 (non-insulin-dependent) diabetes mellitus increases the risk for Type 1 (insulin-dependent) diabetes in siblings of a Type 1 diabetes proband. This increase in risk is consistent with a shared genetic susceptibility between Type 1 diabetes and Type 2 diabetes. We contrast genetic risk factors in three sets of families, consisting of (1) a single Type 1 diabetic child (proband) and non-diabetic parents, (2) multiple Type 1 diabetic siblings and non-diabetic parents, and (3) at least one Type 1 diabetic child and at least one Type 2 diabetic parent. Previous studies have demonstrated that HLA region genes, which elevate the risk in Type 1 diabetes, have no significant effect with respect to the risk for developing Type 2 diabetes. An earlier report cited a contribution by the haptoglobin locus to genetic susceptibility for Type 2 diabetes. We provide evidence that a high risk HLA antigen (HLA-DR3) is decreased to a greater extent in Type 1 patients with a Type 2 parent than in Type 1 patients in which the parents are not diabetic. The role of HLA-DR4 is maintained in these families, with an unexpectedly significant increased rate of transmission of the HLA-DR4 allele from Type 2 parent to Type 1 offspring. The role of haptoglobin in these families does not appear to be important, either with respect to association with diabetes or with respect to linkage with a secondary susceptibility locus. These results indicate that families with a Type 2 parent and Type 1 child, heavily determined by HLA-DR4 linked factors, may represent a homogeneous subset of diabetes susceptibility.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00405008
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  • 7
    Electronic Resource
    Electronic Resource
    The effect of size at birth, maturation threshold and genetic differences on the life-history of Daphnia magna (1991)
    Springer
    Oecologia 86 (1991), S. 243-250 
    Details
    ISSN: 1432-1939
    Keywords: Daphnia ; Life-history ; Genetics ; Variation ; Maturation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Life-history traits of 101 clones from two populations of Daphnia magna were measured under controlled environmental conditions in the laboratory. Some individuals had four juvenile instars, others had five. This depended on their length at birth and on the population they came from. Females in the group with five juvenile instars were smaller at birth but larger and older at maturity than those with four juvenile instars. Within groups of females with equal numbers of preadult instars (instar groups) age and size at maturity increased with size at birth. This relationship differed significantly among instar groups for both age and size at maturity. Significant differences in age and size at maturity between two populations became non-significant when size at birth was used as a covariable in AN-COVA. Within populations, size at birth depended on the clone and on the parity of the clutch. First-clutch offspring were considerably smaller than those from later clutches. The results suggest that variability in life-history traits is common within and between clones, but that most of this variation can be accounted for by size at birth and the number of pre-adult instars.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00317537
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  • 8
    Electronic Resource
    Electronic Resource
    Genetic differences in the effects of competitive and non-competitive NMDA receptor antagonists on locomotor activity in mice (1991)
    Springer
    Psychopharmacology 104 (1991), S. 17-21 
    Details
    ISSN: 1432-2072
    Keywords: MK-801 ; Phencyclidine ; Ketamine ; CGP 39551 ; CGS 19755 ; NPC 12626 ; Locomotor activity ; Genetics ; NMDA/glutamate receptor complex ; Mice
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The effects of non-competitive (MK-801, phencyclidine, and ketamine) and competitive (CGP 39551, CGS 19755, and NPC 12626) N-methyl-d-aspartate (NMDA) receptor antagonists on locomotor activity in inbred CBA and C57, and in outbred NMRI mice were examined. Administration of the non-competitive NMDA antagonists produced a dose-dependent increase in well-coordinated locomotor activity at lower doses, followed by a bizarre behavioral syndrome (head weaving, body rolling, rotations, ataxia) after higher doses. The pharmacological profile of the competitive antagonists CGP 39551, CGS 19755, and NPC 12626 was more complex. CGP 39551 dose-dependently inhibited locomotor activity, whereas CGS 19755 and NPC 12626 displayed a biphasic action, that is low doses inhibited locomotor activity, whereas higher doses produced mild behavioral stimulation. The behavioral effects of NMDA antagonists appear to be genetically determined, since CBA animals were most sensitive to both noncompetitive and competitive antagonists, followed by NMRI and C57 animals. The differential effects of NMDA antagonists in various strains of mice suggest that the observed behavioral differences may be due to genetic differences in the NMDA/glutamate receptor channel complex.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02244548
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  • 9
    Electronic Resource
    Electronic Resource
    Genes encoding ribulosebisphosphate carboxylase and phosphoribulokinase are duplicated in Pseudomonas carboxydovorans and conserved in carboxydotrophic bacteria (1991)
    Springer
    Archives of microbiology 157 (1991), S. 92-96 
    Details
    ISSN: 1432-072X
    Keywords: Carboxydotrophic bacteria ; Ribulosebis-phosphate carboxylase ; Phosphoribulokinase ; Hybridization ; Plasmids ; Genetics ; CO2 fixation ; Alcaligenes eutrophus ; Pseudomonas carboxydovorans ; Rhodospirillum rubrum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Heterologous gene probes derived from cfxLp and cfxPp genes of Alcaligenes eutrophus H16 revealed the presence of structural genes encoding ribulosebisphosphate carboxylase (Rubisco) and phosphoribulokinase (PRK) on the genome of carboxydotrophic bacteria. The two genes were found to be rather conserved. In Pseudomonas carboxydovorans OM5 cfx genes reside on the plasmid pHCG3 and the chromosome as well, indicating that they are duplicated. Also in all plasmidharboring carboxydotrophic bacteria cfxL and cfxP structural genes were found to be plasmid-coded. Our results extend the list of carboxydotrophy structural genes residing on the plasmid pHCG3 and strongly support the idea that the components essential for the chemolithoautotrophic utilization of CO by Pseudomonas carboxydovorans OM5 are plasmid-coded. A cfxL gene probe from Rhodospirillum rubrum did not detectably hybridize with DNA from any of the carboxydotrophic bacteria examined.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00245342
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  • 10
    Electronic Resource
    Electronic Resource
    Evidence that genetic differences in habituation and GABAergic mechanisms may be related to sensitivity to ethanol and development of ethanol tolerance in mice (1991)
    Springer
    Psychopharmacology 105 (1991), S. 13-21 
    Details
    ISSN: 1432-2072
    Keywords: Habituation ; GABA ; Ethanol sensitivity ; Ethanol tolerance ; Genetics ; Mice
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Habituation to a test environment following daily exposure for 5 days was examined in three genetically different strains of mice. C57 animals showed significant habituation to the new environment already on the second day. The habituation of NMRI mice was significant on the third day, whereas CBA mice showed no habituation at all during the experimental period. There was no difference between the animal strains in learning capacity in a passive avoidance test, but CBA mice displayed a significant increase in latency in their performance. When tested for sensitivity to the convulsant actions of GABAergic antagonists, picrotoxin produced seizures at lower doses in CBA as compared to NMRI and C57 mice, whereas there was no difference between the strains in the seizure activity produced by the specific GABA receptor antagonist bicuculline. When the animals were tested for sensitivity to ethanol in a horizontal wire test, ethanol (2 g/kg, IP) produced muscle relaxation in CBA mice whereas the performance of NMRI and C57 was not affected. A large dose of ethanol (4 g/kg, IP) produced a significantly longer sleeping time in CBA mice as compared to NMRI and C57 animals. Ethanol-produced hypothermia was, however, similar in all animals. Environment-dependent development of tolerance to ethanol following daily injections of ethanol for 4 days was examined. C57 mice showed the most rapid development of tolerance towards ethanol's hypnotic actions, whereas CBA mice showed no tolerance to this effect of ethanol. No difference between the strains to the development of tolerance to ethanol's hypothermic effects was observed. The present findings indicate that sensitivity to ethanol and ethanol tolerance are complex phenomena which cannot be adequately characterized by measuring only one single functional response to ethanol. The possibility that a genetically determined perturbation in the functions of the GABA receptor-coupled chloride channel, noted as variable sensitivity to picrotoxin, may be of importance for the observed disturbance in habituation to a new environment, for the different sensitivity to ethanol, and for the different rate of development of ethanol tolerance is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02316858
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  • 11
    Electronic Resource
    Electronic Resource
    Clinical polydiagnostic studies in a large Swedish pedigree with schizophrenia (1991)
    Springer
    European archives of psychiatry and clinical neuroscience 240 (1991), S. 188-190 
    Details
    ISSN: 1433-8491
    Keywords: Families ; Genetics ; Polydiagnostic approach ; Schizophrenia ; Swedish family complex
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A polydiagnostic computerized diagnostic system for psychosis was used in a Swedish family complex, and 51 patients with psychiatric symptomatology were examined with eight main diagnostic systems for schizophrenia and three systems for schizophrenic subgroups. All patients fulfilled the criteria for schizophrenia according to Taylor et al., 50 according to Carpenter, 41 according to RDC, and 31 of the 51 according to DSM-III and DSM-III-R. The hypothesis that the patients in the Swedish family complex differ from other phenotypes of schizophrenia must be refuted based on the data of the present study.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02190762
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  • 12
    Electronic Resource
    Electronic Resource
    Genetic architecture of growth curve parameters in chickens (1991)
    Springer
    Theoretical and applied genetics 83 (1991), S. 24-32 
    Details
    ISSN: 1432-2242
    Keywords: Genetics ; Growth curve ; Body weight ; Chickens
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Genetic improvement in growth of poultry has traditionally proceeded via selection for body weight at a fixed age. Due to increased maintenance costs and reproductive problems of adult broiler breeders, the potential for genetic manipulation of the growth curve has been receiving increased interest. Research of both male and female progeny of a three-way diallel cross was used to investigate the inheritance of growth curve parameters. The Laird form of the Gompertz equation was used to determine growth curve parameters, and was suited to the juvenile growth data frequently collected from meat-type chickens. Growth rate exhibited significant heterosis due to both autosomes and the sex chromosomes. Age at inflection point also exhibited significant average heterosis, though only among females. Growth rate was also influenced by average line effects, as was age at inflection point. Maternal effects had no influence on growth curve parameters, while additive sex linkage was observed for growth rate. Phenotypic and genetic correlations were calculated among the growth curve parameters and suggest that specific breeding programs could alter the growth trajectory of the contemporary broiler chicken. Moderate heritabilities were observed for the growth curve parameters and support the hypothesis that the growth curve could be altered via genetic manipulation of early postnatal growth, especially during the first 14 days post-hatch.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00229222
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  • 13
    Electronic Resource
    Electronic Resource
    Genetic analysis of rye (Secale cereale L.) Genetics of male sterility of the G-type (1991)
    Springer
    Theoretical and applied genetics 82 (1991), S. 761-764 
    Details
    ISSN: 1432-2242
    Keywords: Rye ; Male sterility ; Genetics ; Gene location ; Trisomies
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The genetics and relationships between the genes in rye located in the nucleus and cytoplasm of the male sterility of the G-type were investigated. A factor inducing male sterility was found in the cytoplasms or rye cv Schlägler alt and rye cv Norddeutscher Champagner. Monogenic inheritance was observed in linkage tests. Using primary trisomies of rye cv Esto, the nuclear gene ms1 was found to be located on chromosome 4R. Modifying genes, probably masked in normal cytoplasm but expressed in male-sterility-inducing cytoplasm together with gene ms1, were located on chromosomes 3R (ms2) and 6R (ms3). Mono-, di-, and trigenic inheritance types were found in backcross progenies of trisomies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00227322
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  • 14
    Electronic Resource
    Electronic Resource
    Molecular heterogeneity and genetics of Vicia faba seed storage proteins (1991)
    Springer
    Theoretical and applied genetics 81 (1991), S. 50-58 
    Details
    ISSN: 1432-2242
    Keywords: Vicia faba ; Legumin ; Vicilin ; Structure ; Genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Legumin and vicilin were purified from seeds of Vicia faba L. var. Scuro, characterized in different electrophoretic systems, and used to produce polyclonal antibodies in rabbits. Two-dimensional electrophoretic studies showed a wide range of heterogeneity in the subunits of both legumin and vicilin. Legumin was found to be composed of 29 disulphide-linked subunit pairs with different molecular weight and/or isoelectric point. Western blot analysis of legumin of several mutants revealed molecular polymorphism based on a corresponding gene family. Three different α-major legumin patterns were found, and inheritance studies showed that the 34.3-kD legumin polypeptide is the product of one locus, Lg-1α, which is the first legumin genetic locus described in Vicia faba. Vicilin was found to be composed of as many as 59 subunits distributed in a molecular weight range of 65.7 to 42.8 kD (major polypeptides) and 37.2 to 15.2 kD (minor polypeptides), with different isoelectric points. A model is proposed that explains the possible formation of the minor subunits and the major subunits of 48.2 and 46 kD molecular weight (MW) from proteolytic cleavages and/or glycosilation of precursor polypeptides. Ten different vicilin electrophoretic patterns were observed among the analyzed accessions, which showed large molecular polymorphism that proved to be under genetic control.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00226111
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  • 15
    Electronic Resource
    Electronic Resource
    α-Amylase structural genes in rye (1991)
    Springer
    Theoretical and applied genetics 82 (1991), S. 771-776 
    Details
    ISSN: 1432-2242
    Keywords: Secale cereale ; RFLP ; α-Amylase ; Genetics ; Isozymes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Rye α-Amy1, α-Amy2, and α-Amy3 genes were studied in the cross between inbred lines using wheat α-amylase cDNA probes. The α-Amy1 and α-Amy2 probes uncovered considerable restriction fragment length polymorphism, whereas the α-Amy3 region was much more conserved. The numbers of restriction fragments found and the F2 segregation data suggest that there are three α-Amy1 genes, two or three α-Amy2 genes, and three α-Amy3 genes in rye. These conclusions were supported by a simultaneous study of α-amylase isozyme polymorphism. The F2 data showed the three individual α-Amy1 genes to span a distance of 3cM at the locus on chromosome 6RL. The genes were mapped relative to other RFLP markers on 6RL. On chromosome 7RL two α-Amy2 genes were shown to be separated by 5 cM. Linkage data within α-Amy3 on 5RL were not obtained since RFLP could be detected at only one of the genes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00227324
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  • 16
    Electronic Resource
    Electronic Resource
    Creutzfeldt-Jakob disease among libyan jews (1991)
    Springer
    European journal of epidemiology 7 (1991), S. 490-493 
    Details
    ISSN: 1573-7284
    Keywords: Creutzfeldt-Jakob diseases ; Prion disease ; Jews ; Libya ; Genetics ; Pathophysiology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The focus of CJD among Jews of Libyan origin has been recognized for two decades, but the reasons underlying it were unknown. Prevailing views suggested transmission from sheep infected with scrapie. However, recent data show that in fact CJD in this ethnic group is a genetically determined disease due to a point mutation on the codon 200 of the prion protein gene. The clinical characteristics of CJD in this group, and particularly the less common periodic activity in the EEG, are reviewed. New findings include peripheral neuropathy of the demyelinating type in two cases, presumably due to involvement of Schwann cells. The pathophysiology of the disease includes, presumably, a focal post-translational modification of the prion protein, (predisposed by the mutation). Later, the disease progresses through cell-to-cell transmission.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00143127
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  • 17
    Electronic Resource
    Electronic Resource
    Mutants of Nicotiana plumbaginifolia with specific resistance to auxin (1991)
    Springer
    Molecular genetics and genomics 228 (1991), S. 361-371 
    Details
    ISSN: 1617-4623
    Keywords: Plant ; Hormone ; Genetics ; Hypocotyl ; Development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We have isolated nine independent auxin-resistant mutants of Nicotiana plumbaginifolia by culturing M2 seedlings in the presence of indole-3-acetic acid ethyl ester or 1-naphthaleneacetic acid at concentrations which significantly inhibit hypocotyl elongation of the wild type. The mutations were induced by treating seed with ethyl methanesulphonate and were found in the course of screening 10 000 individual M2 families. Auxin resistance was in all cases the result of a mutation at a single, nuclear locus. The dominance relationships of two of the mutants could be defined as recessive or dominant; all other mutants showed partial dominance. In contrast to previously described mutants of Arabidopsis and N. plumbaginifolia, all of the present mutants were specifically resistant to auxin; the mutants were cross-resistant to several auxins, but showed no increased resistance to cytokinin, abscisic acid, ethylene or 1-amino-cyclopropane-1-carboxylic acid. The importance of the choice of the selection criterion for the isolation of specific resistance traits is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00260628
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  • 18
    Electronic Resource
    Electronic Resource
    Genotype differences in catecholamine concentrations in hypothalamus, intramedial hyperstriatum ventrale, and optic tectum of newly hatched chicks (1991)
    Springer
    Neurochemical research 16 (1991), S. 105-112 
    Details
    ISSN: 1573-6903
    Keywords: Genetics ; catecholamine ; brain ; imprinting ; development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract This study was designed to compare catecholamine concentrations among three brain areas of four pureline populations of visually isolated chicks. The purelines used were a commercial male line, a fertility selected line, an unselected fertility control line, and unselected White Jersey Giants. In general, male chicks had significantly larger brain weights than females. Six catecholamine-related compounds (norepinephrine, epinephrine,l-DOPA, dopamine, DOPAC, and MHPG) were measured via HPLC-ECD. No significant differences in neurochemical concentration were observed for any line or brain area due to sex of the chick. The hypothalamus (HT) contained the greatest concentration of catecholamines in all lines, followed by the intramedial hyperstriatum ventrale (IMHV) and optic tectum (OT). The HT exhibited consistent lateralization in all lines with the right HT containing ca. 30% more catecholamines than the left HT. While no consistent lateralization was observed among the other brain areas, the IMHV exhibited significantly different degrees of lateralization among the populations. Neuronal activity, as measured by MHPG:NE and DOPAC:DA ratio varied by line within each brain area. There were line differences for MHPG:NE in the HT, IMHV, and OT, while line differences for DOPAC:DA were observed in the HT. Since differences among purelines have been demonstrated in this study, care must be given to precisely define the genotype of chicks used in behavioral and neurochemical research.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00965696
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  • 19
    Electronic Resource
    Electronic Resource
    Inheritance of stalk rot resistance in cauliflower (Brassica oleracea var. Botrytis L.) (1991)
    Springer
    Euphytica 57 (1991), S. 93-96 
    Details
    ISSN: 1573-5060
    Keywords: Brassica oleracea ; Cauliflower ; Stalk rot ; Screening ; Genetics ; Resistance ; Sclerotinia sclerotiorum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The inheritance of resistance in cauliflower to stalk rot (Sclerotinia sclerotiorum (Lib.) de Bary) was investigated in population from six generations of six crosses. Disease incidence was recorded on 4 parents, 6 Fs 1, 6 Fs 2 and 12 back-crosses in a screenhouse under artificially created epiphytotic conditions. Resistance to stalk rot in this set of parents was found to be polygenic and under the control of recessive genes and due primarily to additive gene action. A breeding strategy emphasizing recurrent selection should lead to improvement in resistance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00023065
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  • 20
    Electronic Resource
    Electronic Resource
    Crystallization kinetics of poly(ethylene terephthalate). Part I: Kinetic equation with variable growth rate (1991)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 31 (1991), S. 110-115 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A new crystallization kinetic equation has been derived considering the decrease in growth rate. The average linear growth rate of spherulite was assumed to be proportional to the m-th order of the uncrystallized fraction of the crystallizing material. A modified Avrami equation, 1 - Vc = exp[-Kf(t)n], was used where f(t) is the integral of the growth function, (1 - Vc)m. The validity of the equation was tested by analyzing the isothermal crystallization kinetic data of poly(ethylene terephthalate) from the melt using differential scanning calorimetry.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760310209
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  • 21
    Electronic Resource
    Electronic Resource
    The coupled relaxation model for toner melt rheology (1991)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 31 (1991), S. 99-103 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Process changes aimed at improving printer engine performance must take into consideration not only the process variables (such as nip temperature and pressure and process time to), but also the melt rheological variables (such as the characteristic time scale of the toner Tc). The melt rheology relevant to the electrophotographic toner fusing process is discussed. One criterion for toner quality can be conveniently measured through the Deborah number De, which is the ratio of Tc to to. Modification of the melt rheology by matrix polymer composition and carbon black size and concentration has previously been explored. Here, the melt rheology of toners with a range of gel content was studied using a step shear test. The coupled relaxation model was employed to fit the stress relaxation data. The viscoelastic properties were calculated from the melt data with this model. These properties were then used to estimate the strain deformation of the toner as it passes through the nip with arbitrary residence time and nip pressure as a function of gel content. This method can be used to match the toner melt properties with the processing conditions.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760310207
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  • 22
    Electronic Resource
    Electronic Resource
    Masthead (1991)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 31 (1991) 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760310301
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  • 23
    Electronic Resource
    Electronic Resource
    A unified simulation of the filling and postfilling stages in injection molding. Part II: Experimental verification (1991)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 31 (1991), S. 125-139 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The unified numerical simulation of the filling/postfilling stages of the injection-molding process described in Part I is compared in the present paper with experimental results obtained with instrumented test molds. Flush-mounted pressure traces in the delivery system as well as in the cavity are favorably compared with corresponding predictions for both an amorphous and a semicrystalline polymer. It is demonstrated that the present unified formulation is well suited to handle complicated molds where compressibility effects can become important even during the filling stage, as portions of the cavity fill and undergo a packing behavior even when other regions of the cavity are still only partially filled.
    Additional Material: 19 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760310211
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  • 24
    Electronic Resource
    Electronic Resource
    A unified simulation of the filling and postfilling stages in injection molding. Part I: Formulation (1991)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 31 (1991), S. 116-124 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: This study employs a unified theoretical model to simulate the filling and postfilling stages of the injection-molding process. Implementation of such a model is based on a hybrid finite-element/finite-difference numerical solution of the generalized Hele-Shaw flow of a compressible viscous fluid under nonisothermal conditions. The shear viscosity of the polymeric material is represented by a Cross model for the shear-rate dependence and a WLF-type functional form for the temperature and pressure dependence, whereas the specific volume is modeled in terms of a double-domain Tait equation. The analysis also handles variable specific heat and thermal conductivity of the polymer as a function of temperature. Complex thin parts of variable thickness can be modeled and discretized by flat, triangular finite elements which may have arbitrary orientation in three-dimensional space, whereas runners and possible round pins or bosses in the part are represented as one-dimensional circular-tube elements. A control-volume scheme is employed that leads to automatic melt-front advancement during the cavity-filling stage.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760310210
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  • 25
    Electronic Resource
    Electronic Resource
    Models for the compressibility of layered polymeric sponges (1991)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 31 (1991), S. 140-144 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The characteristic sigmoid compressive stress-strain relationships of sponges and their layered arrays are described by two kinds of mathematical models having three experimentally determined parameters. Since sponge compression is not accompanied by a significant cross-sectional area expansion, it was assumed that the stress in a multilayered array is the same in each layer. This enables prediction of the array's stress-strain relationship from the parameters of the individual layers and their known thickness. The applicability of the method is demonstrated with experimental data of two kinds of double-layered arrays of polyurethane sponges. It is shown that the arrays' compressive behavior can be satisfactorily predicted irrespective of the mathematical form of the model and whether the strain is expressed as engineering strain or Hencky's.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760310212
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  • 26
    Electronic Resource
    Electronic Resource
    Development of density distributions in injection molded amorphous engineering plastics. Part I (1991)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 31 (1991), S. 145-152 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The gapwise density distributions of the injection molded specimens of two engineering thermoplastics, i.e., poly(phenylene ether) and poly(ether imide), were characterized employing the density gradient column technique. The samples were molded using a 40t Van Dorn injection molding machine. The effects of the thermal history on the density distribution of unconstrained quenched specimens were also investigated. In addition, various material properties, such as pressure-volume-temperature, isothermal contraction, and pressure induced densification behavior were characterized, for the two resins employed in this study. The moldings of the two resins exhibited different trends in their density distributions. These findings were explained in terms of the competing effects of cooling rate and the pressure history experienced by the engineering plastic resins during the molding cycle. The data collected were also used as input to mathematical modeling of density distributions in injection molded articles, which is reported in Part II of this article.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760310302
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  • 27
    Electronic Resource
    Electronic Resource
    Steady solidification of non-Newtonian fluid flowing in a round tube (1991)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 31 (1991), S. 191-196 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The problem of steady solidification of a power law fluid flowing in a round tube was solved numerically. The fluid considered was a polymer with temperature dependent viscosity. The mathematical solution was obtained by using an implicit finite difference method. Results are presented to show the effects of the Peclet number, Nahme number, and the power law index on the profiles of the frozen layer. Melt temperature profiles at different axial locations are also presented.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760310306
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  • 28
    Electronic Resource
    Electronic Resource
    Masthead (1991)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 31 (1991) 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760310401
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  • 29
    Electronic Resource
    Electronic Resource
    A study on bicomponent two-layer slot cast coextrusion (1991)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 31 (1991), S. 197-203 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Extensional flow of a bicomponent two-layer slot cast coextrusion process has been studied. A Newtonian and an upper-convected Maxwell fluid were considered to be the two layers, respectively, and the two-layer flow was assumed to be steady and isothermal. This choice was made as a simple model for a system which consists of two distinctly different fluids in terms of their extensional behaviors. Present study considered only the draw-down region where the film thickness changes slowly with the distance from the die exit. For this region, asymptotic solutions could be obtained for two limiting cases in which the elasticity effect of the Maxwell fluid layer is small and the applied tension at the take-off is large, respectively. When the elasticity effect is small, the melt thickness and the velocity profiles are exponential as in the case of a Newtonian single-layer flow. When the applied tension is large, on the other hand, the velocity profile is shown to be near linear. Furthermore, the viscoelasticity effect of the Maxwell fluid layer becomes so dominant that it dictates the mechanics of the coextrusion flow even when its flow rate and shear viscosity may be much smaller than those of the Newtonian layer.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760310307
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  • 30
    Electronic Resource
    Electronic Resource
    Masthead (1991)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 31 (1991) 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760310501
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  • 31
    Electronic Resource
    Electronic Resource
    An experimental study of multiobjective dynamic optimization of a semibatch copolymerization process (1991)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 31 (1991), S. 353-364 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Optimal open loop control strategies are developed for a semibatch free radical copolymerization of methyl methacrylate and vinyl acetate using the multiobjective dynamic optimization method. A detailed kinetic model is validated through experimentation and used for the design of optimal controls. Both monomer feed rate and reactor temperature are varied to produce the copolymer of desired composition and molecular weight. The open loop control policies are implemented in a process control computer and tested on an experimental stirred tank polymerization system. Excellent agreement between the model predictions and the experimental data have been obtained.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760310507
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  • 32
    Electronic Resource
    Electronic Resource
    Dynamics of a cascade of two continuous stirred tank polymerization reactors with a binary initiator mixture (1991)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 31 (1991), S. 333-352 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The dynamic behavior of two continuous stirred tank reactors in series has been investigated for free radical solution polymerization of styrene with a binary mixture of two initiators having different thermal decomposition activities. For a wide range of initiator feed composition, both reactors exhibit quite complex nonlinear steady state and transient behavior. When the reactor residence time is used as a bifurcation parameter, the second reactor can have up to five steady states. For certain range of reactor operating conditions, bifurcations to various types of periodic solutions have been observed, such as Hopf bifurcation, isolas, period doubling, period-doubling cascade, and homoclinics. The effects of other reactor variables, such as total initiator concentration, coolant temperature, and reactor volume ratio on the reactor dynamics, are illustrated to show the complex dynamic behavior of the two-reactor system catalyzed by a mixture of t-butyl perbenzoate and benzoyl peroxide.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760310506
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  • 33
    Electronic Resource
    Electronic Resource
    Development of an in-line rheometer suitable for reactive extrusion processes (1991)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 31 (1991), S. 365-375 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: This paper presents the development of a novel in-line extrusion rheometer based on the flow of polymer through a wedge (vertically tapered slit). This rheometer is suitable for measuring changes in rheological properties on-line during reactive extrusion, because it can be used to estimate the viscosity for a range of shear rates without the need to change the polymer flow rate (i.e., extruder throughput). Equations have been developed to estimate the parameters of the power-law equation, used to describe the viscosity-shear rate relationship, from measurements of pressure drops along the wedge. An experimental in-line wedge rheometer has been built and used to measure the viscosity for a series of polypropylenes prepared via reactive extrusion. Viscosity measurements from the experimental in-line wedge rheometer are compared with measurements from a capillary rheometer. Good agreement is found between the capillary and wedge rheometer measurements.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760310508
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    Electronic Resource
    Electronic Resource
    Correction (1991)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 31 (1991), S. 391-391 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760310511
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  • 35
    Electronic Resource
    Electronic Resource
    Masthead (1991)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 31 (1991) 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760310101
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  • 36
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    Electronic Resource
    The design and manufacture of a graphite fiber reinforced poly(ether ether ketone) (PEEK) tetrahedron truss array (1991)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 31 (1991), S. 1-5 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Orbital space structures are required to be lightweight, have high specific stiffness, have near-zero coefficient of thermal expansion, exhibit low outgassing, and be cost-effective. Graphite-reinforced thermoplastics have the potential to satisfy the criteria noted. However, prior to committing the materials to specific projects, technology demonstration and risk reduction is necessary. In order to demonstrate the application of fiber-reinforced thermoplastic composites for truss structure applications, a graphite-reinforced poly(ether ether ketone) (PEEK) composite tetrahedron truss array was designed and manufactured. The resulting structure clearly demonstrated that fiber-reinforced thermoplastic composites are a viable alternative to epoxy composites for orbital structures.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760310102
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  • 37
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    Electronic Resource
    371°C (700°F) properties of celion 6000/N-phenylnadimide modified pmr polyimide compositesPart of this work was performed under the auspice of the Polymer Composite Branch of the Materials Division, NASA-Lewis Research Center, Cleveland, Ohio. (1991)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 31 (1991), S. 14-19 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The 371°C (700°F) properties of Celion 6000/N-phenylnadimide modified PMR-15 polyimide composites were investigated to determine the feasibility of using these materials at a 371°C (700°F) service temperature. The processing characteristics and physical and mechanical properties of the composite systems are presented. The results of the 371°C thermooxidative stability study suggest that the composite materials can be considered for short-term (at least 100 hours) application at 371°C.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760310104
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  • 38
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    Electronic Resource
    Mechanical properties and mechanism of the degradation process of 316°C isothermally aged graphite fiber/PMR-15 composites (1991)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 31 (1991), S. 6-13 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A series of graphite fiber/PMR-15 polyimide composites, isothermally aged at 316°C in flowing air (100 cc/min) for time periods up to 2000 h, were investigated for mechanical property changes, fiber/resin interface changes, overall dimensional changes, and weight loss. The mechanism of the degradation process is suggested based on shear and flexural property measurements at room temperature and 316°C, optical micrographs of composite cross sections, and SEM analysis of fractured surfaces. The fiber materials investigated in composite form were Celion 6000 unsized and epoxy sized. G40-700 unsized and epoxy sized, and T40R and IM6 both unsized.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760310103
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  • 39
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    Interpenetrating polymer network approach to tough and microcracking resistant high temperature polymers. Part III. LaRC-RP71 (1991)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 31 (1991), S. 28-33 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A high performance semi-interpenetrating polymer network (semi-IPN) has been synthesized from Thermid-600 and LARC-TPI. Notable improvements in resin fracture toughness and graphite fiber reinforced composite microcracking resistance over the unmodified Thermid-600 neat resin and composite have been realized. The chemistry, processing, physical and mechanical properties, and phase morphology of the neat resin and composite reinforced with graphite fibers are presented.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760310106
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  • 40
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    Interpenetrating polymer network approach to tough and microcracking resistant high temperature polymers. Part II. LaRC-RP41 (1991)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 31 (1991), S. 20-27 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Recently, we reported on the interpenetrating polyimide network (IPN) approach to develop tough and microcracking resistant high temperature matrix resins for use in aircraft/aerospace structural components. One such polymer developed is designated LaRC-RP40. This new simultaneous semi-IPN was prepared from easy-to-process but brittle crosslinking PMR-15 and tough but difficult-to-process linear NR-150B2. Significantly improved toughness, microcracking resistance, and glass transition temperature over PMR-15 were realized from the combination. These property improvements were achieved without compromising ease of processing, high temperature mechanical performance, and cost effectiveness compared to PMR-15. These results encouraged us to further explore this approach for the development of a wider range of polymers of basic technological and economic interest. In the present work, we combine crosslinking PMR-15 and linear LaRC-TPI to provide a new sequential semi-2-IPN called LaRC-RP41. The physical and mechanical properties of the neat resin and composite reinforced with graphite fibers are presented. The phase morphology and phase stability of the neat resin and composite studied by various techniques are also discussed.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760310105
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  • 41
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    Mechanical properties in multidimensional composites (1991)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 31 (1991), S. 40-46 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The mechanical properties of three dimensional stitched composites were compared against those of the traditional two dimensional laminates. An attempt was made to correlate the change in properties to the change in the third directional fiber density. Tests conducted were the impact, three-point bending, damage tolerance, end notched flexure, and bending fatigue test. The results of these tests show that the third directional fibers can effectively inhibit delamination by increasing the interlaminar shear strength. Three dimensional composites also possess better damage tolerance, fracture toughness, and fatigue life. However, a high stitching density can degrade the in-plane properties of the composites.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760310108
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  • 42
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    Environmental effects on the water absorption and mechanical properties of carbon fiber reinforced PPS and PEEK composites. Part II (1991)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 31 (1991), S. 34-39 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Research has been conducted to investigate the water absorption in carbon fiber reinforced poly(ether ether ketone) (PEEK/CF) and poly(phenylene sulfide) composites (PPS/CF). Effect of humidity and temperature on tensile, flexural, and impact strength of these composites were also studied. Results indicated that the water absorbed in PPS/CF and PEEK/CF are 0.059 %wt, 0.130 %wt, 0.138 %wt, and 0.153 %wt at 80°C. 75 %RH and 85 %RH, respectively. The diffusion process is a classical Fickian diffusion in the temperature range investigated. The activation energies of diffusion are 667 cal/g-mole (for PPS/CF) and 8934 cal/g-mole (for PEEK/CF) at 80°C and 75 %RH. The retention of mechanical properties of these composites is very good under hot-wet conditions. These composite materials can be served as high performance materials even in the hostile environment. PEEK/CF composites shows excellent mechanical properties retention even at 80°C, 75 %RH, and 85 %RH.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760310107
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    Vibration based non-destructive evaluation of polymer composites (1991)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 31 (1991), S. 47-55 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A feasibility study on the use of vibration spectrum analysis as a tool for nondestructive evaluation (NDE) of polymer composites was conducted. Material integrity of polymer composite samples was determined from the vibrational measurements by analyzing the resonant frequency and damping information. A number of important “states” in the composites tested could be characterized by this analysis. The vibration tehnique was found to be sensitive to physical flawing (fiber breakage, delamination, and matrix cracking). Vibrational NDE has many potential advantages that make it very attractive for composite applications. These include the ability to make global measurements of large structures in real-time, no geometry restrictions, and high sensitivity to a wide variety of damage states.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760310109
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    In-situ monitoring of the resin transfer molding impregnation and cure process (1991)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 31 (1991), S. 56-60 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Resin transfer molding (RTM) of advanced fiber architecture materials promises to be a cost effective process for obtaining composite parts with exceptional strength. However there are a larger number of material processing parameters that must be observed, known, and/or controlled during the resin transfer molding process. These include the viscosity both during impregnation and cure. In-situ sensors which can observe these processing properties within the RTM tool during the fabrication process are essential. This paper will discuss recent work on the use of frequency dependent electromagnetic sensing (FDMS) techniques to monitor these properties in the RTM tool. Our objective is to use these sensing techniques to address problems of RTM scaleup for large complex parts and to develop a closed loop, intelligent, sensor controlled RTM fabrication process.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760310110
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    Gas-liquid two-phase flow in symmetrically dividing horizontal tubes (1991)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 37 (1991), S. 111-122 
    Details
    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 time-averaged void fraction, pressure drop and flow regime transition behavior of horizontal air-water two-phase flows is studied experimentally and numerically for 2-cm-inner-diameter tubes with various flow dividing junctions at its end. The time-average void and pressure drop behavior along the channel is simulated using a two fluid separated flow model. The results show that two-phase behavior (flow regime, void fraction, and pressure drop) is affected strongly by the presence of a flow division in the system. These effects extend far upstream of the junction for low-momentum flows and far downstream for high-momentum flows. Both numerical and experimental results show that there occurs a large increase in void just downstream of the junction owing to the halving of the fluid volume flow rates and the liquid deceleration.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690370110
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    Fault diagnosis in complex chemical plants using artificial neural networks (1991)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 37 (1991), S. 137-141 
    Details
    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
    URL: http://dx.doi.org/10.1002/aic.690370112
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    Masthead (1991)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 37 (1991) 
    Details
    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
    URL: http://dx.doi.org/10.1002/aic.690370201
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  • 48
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    Influence of chemical and electrostatic gradients on diffusion in microemulsions (1991)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 37 (1991), S. 169-181 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Nonequilibrium diffusion behavior in nonionic and ionic surfactant microemulsion systems has been studied experimentally using the open-ended capillary method. Experimental results for these systems have been compared with a drop theory of diffusion for microemulsions under conditions where large concentration and electrostatic gradients exist. The results show good agreement in concentration profiles between theory and experiment for the microemulsion components - water, benzene, and phenol. Furthermore, under certain conditions the theory predicts that over a limited time interval phenol will diffuse from low-concentration regions to regions of higher concentration. This phenomenon has been observed.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690370203
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    Use of a second endothermic reaction to desensitize a tubular reactor (1991)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 37 (1991), S. 225-232 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Three parametric sensitivity criteria were examined for application to a pseudohomogeneous tubular reactor system, in which both methanol dehydration (exothermic) and methanol dissociation (endothermic) were catalyzed. The addition of the endothermic reaction was shown to lead to a desensitized reactor. It was illustrated, however, that the relative activities of the two catalysts should be somewhat similar to maintain the overall conversion of the resulting reactor for a given residence time.The three criteria investigated tended to disagree with one another more, as the system was made less sensitive by the addition of more endothermic catalyst. A potential application of the resulting nonsensitive reactor design would be in methanol-fueled vehicles.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690370208
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  • 50
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    Spray-to-bubbly transition for distillation systems containing two liquid phases (1991)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 37 (1991), S. 597-606 
    Details
    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 tray hydrodynamics were determined for a system containing water and kerosene as immiscible liquids. Plates with hole diameters ranging from 3.18 to 12.70 mm were used in a 44.5-cm2 perspex air-water-kerosene simulator. Experiments were also carried out in a 50-mm-ID column using different depths of oil and water mixtures to study the drop and bubble mechanisms. A spray-to-bubble transition occurred for the two liquid-phase system experiments. The liquid holdup at the transition increased directly with gas velocity and hole diameter, and decreased with increasing free area. At the same hole velocity, the presence of two liquid phases caused the transition to occur at different liquid holdups than for the single pure liquid. Two different modes of coalescence were observed in the small column work. New correlations have been proposed for the liquid holdup at the transition which allow for the presence of two liquid phases.
    Additional Material: 21 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690370413
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    Letters to the editor (1991)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 37 (1991), S. 791-799 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690370517
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    In transition (1991)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 37 (1991), S. 803-803 
    Details
    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
    URL: http://dx.doi.org/10.1002/aic.690370603
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    Masthead (1991)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 37 (1991) 
    Details
    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
    URL: http://dx.doi.org/10.1002/aic.690370701
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  • 54
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    Gas-solid flow in vertical tubes (1991)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 37 (1991), S. 1009-1018 
    Details
    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 computational study of fully-developed flow of gas-particle suspensions in vertical pipes was carried out, using the model proposed recently by Sinclair and Jackson (1989), to understand the predicted scale-up characteristics. It was shown that the model can capture the existence of steady-state multiplicity wherein different pressure gradients can be obtained for the same gas and solids fluxes. A pronounced and nonmonotonic variation of the pressure gradient required to achieve desired fluxes of solid and gas with tube diameter was predicted by the model, and this is explained on a physical basis. The computed results were compared with the experimental data. The model manifests an unsatisfactory degree of sensitivity to the inelasticity of the particle-particle collisions and the damping of particle-phase fluctuating motion by the gas.
    Additional Material: 18 Ill.
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    URL: http://dx.doi.org/10.1002/aic.690370706
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    Liquid saturation data in trickle beds operating under elevated pressure (1991)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 37 (1991), S. 1109-1112 
    Details
    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: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690370717
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  • 56
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    L-serine obtained by methanol addition in batch crystallization (1991)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 37 (1991), S. 1121-1128 
    Details
    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 solubility of L-serine in water was measured as a function of temperature, and the solubility in methanol-water solutions was determined as a function of temperature and methanol concentration. Solubility in aqueous solutions was found to be a linear function of temperature. Additionally, a statistical design of experiments was used to identify the kinetic variables that influence the purity of L-serine crystals recovered by batch crystallization. Agitation and the rate at which super-saturation was generated through cooling and methanol addition were found to influence the methanol content of the recovered crystals. The size of the recovered crystals also was found to depend on agitation and the rate at which methanol was added to the L-serine mother liquor.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690370802
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  • 57
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    Emulsion layer model for wall heat transfer in a circulating fluidized bed (1991)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 37 (1991), S. 1139-1150 
    Details
    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 emulsion layer model is presented which predicts the thickness of a downward-moving emulsion layer along the wall of a circulating fluidized bed, the mean solids velocity, and the solids flux in the layer. Also presented is a heat transfer model which, in combination with the emulsion layer model, predicts the low-temperature data very well. An alternate slab model proposed for the radiative component in a high-temperature circulating fluidized bed agrees well with experimental data. The heat transfer predictions of the overall model for such operating parameters as solid circulation flux, suspension temperature, length of the heat transfer surface, superficial gas velocity, and mean particle size are in good agreement with the published data for long surfaces.
    Additional Material: 15 Ill.
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    URL: http://dx.doi.org/10.1002/aic.690370804
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    Water and ethanol sorption phenomena on starch (1991)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 37 (1991), S. 1187-1195 
    Details
    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 sorption behavior of water and ethanol on starch material has been investigated in relation to the adsorptive separation of water from ethanol. The adsorption isotherms of water-starch, ethanol-starch and water-ethanol-starch were measured using a Cahn electrobalance. Careful examination of the many sorption isotherm models resulted in selection of Sircar's model and the potential theory to best represent the isotherm data of water-starch and ethanol-starch adsorption. Experimental results showed that ethanol as well as water can adsorb on starch. The adsorption rate of ethanol, however, is much slower than that of water. This suggests that the selective removal of water from ethanol vapor in a packed-bed adsorber is likely a rate-dependent, not an equilibrium-dependent, process.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/aic.690370808
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    Influence of operating and physical variables on interfacial area determination (1991)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 37 (1991), S. 1196-1204 
    Details
    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 influence of various operating and liquid-phase physical variables on interfacial area ab in cylindrical and spherical gas-liquid stirred contactors was studied using the sulfite method. Studied were stirring speed, sparger porosity, gas flow rate, liquid-phase temperature, surface tension, and pH.The results show that the influence of operating variables (gas flow rate Qg, stirring speed ω, and the average pore radius of the sparger used rp) on ab, for both types of contactors, can be given by the equation: \documentclass{article}\pagestyle{empty}\begin{document}$$ a_b = Q_g^{0.5} \left({\frac{{k_1 }}{{k_2 }} + \frac{{k_2 }}{{r_p^{1.5} }}\omega } \right) $$\end{document} Dependency of ab on surface tension observed was believed to be caused by a rising rate of bubble coalescence with increased surfactant concentration. The higher the surfactant concentration, the lower ab, tending to a limit that depends on both the type of surfactant and the average size of sparger pore used. Due to the measurement method used, solution pH and temperature were also observed to influence ab.
    Additional Material: 9 Ill.
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    URL: http://dx.doi.org/10.1002/aic.690370809
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    Quantitative description of ultrafiltration in a rotating filtration device (1991)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 37 (1991), S. 1219-1226 
    Details
    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 correlation was developed to quantitatively describe the flux in a high-speed rotating filtration device using a minimum set of parameters. The experimental results were found to be consistent with the concentration polarization (CP) model. Beyond a threshold pressure flux ceases to depend on membrane permeability. The CP model was modified to include the concentration dependence of the diffusivity. This approach was found to be consistent with the strong dependence of flux on pH. Protein concentration in the polarized layer adjacent to the membrane surface was estimated using a procedure that corrects for some of the inconsistencies in the methods usually applied. Four dimensionless numbers were necessary to correlate the experiments with good accuracy. Previously-reported correlations used only three dimensionless numbers. Usage of four numbers could be justified by dimensional analysis. Finally, the performance of rotary or vortex filtration was compared to that of other configurations.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/aic.690370811
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    Continuous olefin copolymerization with soluble Ziegler-Natta catalysts (1991)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 37 (1991), S. 1255-1260 
    Details
    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
    URL: http://dx.doi.org/10.1002/aic.690370817
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    Statistical analysis of anomalous transport phenomena in complex media (1991)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 37 (1991), S. 1249-1254 
    Details
    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
    URL: http://dx.doi.org/10.1002/aic.690370816
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    Determining external film mass transfer coefficients for adsorption columns (1991)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 37 (1991), S. 1270-1274 
    Details
    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
    URL: http://dx.doi.org/10.1002/aic.690370820
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    Transient deformation of freely-suspended liquid droplets in electrostatic fields (1991)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 37 (1991), S. 1305-1317 
    Details
    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 problem of freely-suspended liquid droplets deforming due to an applied electrostatic field is examined. Developed is a numerical model capable of predicting the complete transient histories of droplets in systems with a wide range of dispersedand continuous-phase densities, viscosities, relative permittivities, and electric field strengths. For liquid/gas systems, the predictions of the numerical model demonstrated that the critical field strength and critical permittivity ratio during actual transient breakup are not necessarily the same as those predicted by steady-state theories. An approximate analytical model of transient droplet deformation is also developed, which is able to predict the deformation time histories for large Ohnesorge number, small-deformation liquid/liquid systems. The approximate analytical model agreed well with the results of the complete numerical model.
    Additional Material: 12 Ill.
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    URL: http://dx.doi.org/10.1002/aic.690370904
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    A series solution for mass transfer in laminar flow with surface reaction (1991)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 37 (1991), S. 1341-1353 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: We present an explicit analytical solution for the Lévêque's problem with the boundary condition of the third kind. This solution is applicable to problems of mass (heat) transfer with surface reaction (surface resistance) in the entry region of fully developed flow fields of power law fluids, and to the developing boundary layer flows that admit Falkner-Skan solutions, provided that the Schmidt (Prandtl) number is large. The series form of the solution developed by inversion of the Laplace transform has excellent convergence properties within the concentration (temperature) boundary layer in contrast to the integral forms that are usually reported for problems of this type. An efficient computational algorithm for evaluation of the surface concentration is presented, as well as accurate approximate formulas in the form of simple algebraic expressions for the local and average mass (heat) transfer coefficients and the surface concentration (temperature).
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/aic.690370907
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    Microwave thawing of cylinders (1991)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 37 (1991), S. 1789-1800 
    Details
    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 finite element method was used to model microwave thawing of pure-water and 0.1-M NaCl cylinders. The electromagnetic field was described by Maxwell's equations with temperature-dependent dielectric properties, while the heat equation, coupled with the Stefan and Robin conditions, was used to describe the thawing process. An additional equation for the frozen volume fraction was used, when necessary, to account for the presence of a mushy region. Two microwave frequencies, 915 MHz and 2,450 MHz, were examined and the microwave radiation was assumed to be radially isotropic and normal to the surface of the cylinder. Results show that a two-phase mushy region may exist, and an additional thawing front may appear at the center of the cylinder. Salt cylinders have a higher dielectric loss than pure-water cylinders and therefore thaw more quickly. Internal resonance occurs when the wavelength of the radiation is a harmonic of the cylinder radius. Resonance increases power deposition and expedites the thawing process. The onset of resonance alters thawing times and complicates the development of heuristic rules for microwave thawing.
    Additional Material: 12 Ill.
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    URL: http://dx.doi.org/10.1002/aic.690371204
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    Effect of electrode surface area on chaotic attractor dimensions (1991)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 37 (1991), S. 1833-1843 
    Details
    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 experimental study of the dynamics of electrodissolution of iron in sulfuric acid is reported. The experiments were done under potentiostatic conditions with a rotating disk electrode as a function of two parameters, potential and electrode diameter. The dynamic behavior depends strongly on the latter parameter; with increasing electrode size we observe transitions from periodic oscillations to low-order chaos to higher-order chaos. The attractor dimension increases with increasing electrode size. In addition, for the large electrodes at more positive potentials, a secondary higher frequency oscillation also arises.
    Additional Material: 30 Ill.
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    URL: http://dx.doi.org/10.1002/aic.690371208
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    Generalized approach toward modeling resist performance (1991)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 37 (1991), S. 1863-1874 
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    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 generalized technique for modeling resist performance is outlined. In this approach, the fraction of resist remaining after development as a function of incident dose, or characteristic curve, is related to the development rate which is assumed to be a power law of a dominant soluble species. Soluble species are either photochemically consumed for negative resists or generated for positive. Expressions for the dependence of characteristic curves on exposure dose and chemistry are derived for various resist systems, which are consistent with current models. For similar chemical kinetics, negative resists yield fewer lumped parameters to describe their development rate and characteristic curves than positive.Under conditions of negligible surface inhibition, lumped parameters can be extracted from characteristic curves and used to simulate lithography. A generalized method to correct for absorption in the resist and reflections is outlined. Exposure latitude was accurately predicted for a commercial negative chemically amplified resist. However, prediction of linewidths from characteristic curves of positive resists is complicated by surface inhibition effects.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/aic.690371211
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    Robust process control. By Manfred Morari and Evanghelos Zafiriou, Prentice-Hall, Inc., Englewood Cliffs, NJ, 1989, 488 pp., $55.00 (1991)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 37 (1991), S. 1905-1906 
    Details
    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
    URL: http://dx.doi.org/10.1002/aic.690371216
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    Curvature and parametric sensitivity in models for adsorption in micropores (1991)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 37 (1991), S. 429-436 
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    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 sensitivity of the calculated micropore size of zeolite Y in a fluidized cracking catalyst based on empirical models for argon adsorption has been tested by examining the effect of curvature and by systematically verifying the magnitude of physical constants in the model equations. With a consistent set of physical parameters the slit model provided a pore size value of 0.45 nm, while the new cylindrical models provided values of 0.69 and 0.74 nm. The latter values are found to correspond well with the known aperture size of zeolite Y, 0.74 nm. By separately varying the magnitudes of five of the physical constants in the model over a range of ±30%, it was concluded that the diameter of the oxide ion at the surface had a large effect on the calculated pore size, while the other parameters had only moderate to small effects. Preliminary application of the cylindrical pore model to isotherms of argon on other zeolites and molecular sieves leads to promising results, especially for medium to large pore zeolites. These results suggest that the cylindrical pore model is a useful means for the transformation of argon adsorption data on a zeolite into a micropore size distribution.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/aic.690370312
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    Approximate models for nonlinear adsorption in a packed-bed adsorber (1991)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 37 (1991), S. 461-465 
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    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690370315
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    Prediction of the three-dimensional turbulent flow in stirred tanks (1991)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 37 (1991), S. 448-460 
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    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Efforts to model the turbulent flow in stirred tanks require accurate boundary conditions at the tip of the impeller, not just of velocities, but of the turbulence quantities k and ε. Kolar's (1982) phenomenological, swirling radial jet model of the impeller region is extended by using a two-equation k - ε turbulence model to obtain direct estimates of k and ε on the impeller periphery. The model is extended and clarified, so that the number of parameters required for its application is reduced to two: the rotational speed and the diameter of the impeller. Three-dimensional simulations allow a realistic treatment of the baffles. Agreement of the modeling results with recently published experimental data is excellent. This is particularly true in the important impeller discharge zone, where details of the predicted behavior of the turbulence kinetic energy and dissipation rate are in quantitative agreement with the available data. Based on these results, average values of ε are calculated, along with the zones over which the apply. For the impeller discharge zone, the dimensionless, volume-averaged ε is 0.19.
    Additional Material: 13 Ill.
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    URL: http://dx.doi.org/10.1002/aic.690370314
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    Analysis of a photochemical film reactor (1991)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 37 (1991), S. 475-479 
    Details
    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
    URL: http://dx.doi.org/10.1002/aic.690370319
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    Multiple steady states in ideal two-product distillation (1991)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 37 (1991), S. 499-511 
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    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Simple distillation columns with ideal vapor-liquid equilibrium may display multiple steady-state solutions. Two fundamentally different sources for the multiplicity are presented. Both bring about the unexpected result that increasing reflux makes separation worse in the top part of the column. It corresponds to an unstable operating point.The first type of multiplicity is found for columns with mass or volume inputs (e.g., mass reflux and molar boilup). Even for constant molar flows, the transformation from the actual input units to molar units may become singular (corresponding to a pitchfork bifurcation point), resulting in multiple steady-state solutions. The results are highly relevant in practice, as industrial columns usually have inputs on a mass or volume basis. The second type for specifications on a molar basis (e.g., molar reflux and molar boilup) depends on the presence of an energy balance in the model. The multiplicity is caused by interactions between flows and compositions in the column.
    Additional Material: 10 Ill.
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    URL: http://dx.doi.org/10.1002/aic.690370404
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    Pressure buildup and internal stresses during binder burnout: Numerical analysis (1991)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 37 (1991), S. 547-554 
    Details
    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 interstitial pressure buildup and the internal stresses on the skeleton of a cylindrical green body during burnout are analyzed numerically. The intrinsic kinetics of pyrolysis is coupled with the Carman-Kozeny equation or the slip-flow model of Wakao and Smith to evaluate the pressure distribution. The stress distributions before failure are estimated from elasticity theory. The stresses are tensile, and their maxima are located at the center of the cylinder. The tangential stress is larger than the radial stress. The effects of green body size, specific surface area, and pressurized atmosphere are discussed. The approximate solution is accurate for small green bodies. The pressurized atmosphere reduces the interstitial pressure and the internal stresses effectively.
    Additional Material: 8 Ill.
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    URL: http://dx.doi.org/10.1002/aic.690370408
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    Fault diagnosis based on qualitative/quantitative process knowledge (1991)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 37 (1991), S. 617-628 
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    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Recent advances in knowledge engineering have led to develop the qualitative (deep) model based diagnostic systems. As process knowledge accumulated, however, the diagnostic system remains strictly qualitative. This limits the usefulness of such systems. In this work, a framework is developed for integrating quantitative process knowledge into the qualitative model. Once quantitative process information, e.g., steady-state gains, is available, it can be incorporated into the simplest qualitative process model called the signed directed graph. The quantitative process knowledge is described in terms of membership functions of fuzzy set theory. According to the measurement pattern, the truth values of a hypothesis (e.g., a fault origin) can be calculated based on the fuzzy logic. Consequently, the diagnostic resolution can be improved significantly. Furthermore, the proposed method becomes a strictly qualitative diagnostic system, if no quantitative information is available. A chemical reactor example illustrates the design and performance of the qualitative/quantitative model-based diagnostic system. The proposed approach can also be extended to the multiple-fault situations in a straightforward manner.
    Additional Material: 18 Ill.
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    URL: http://dx.doi.org/10.1002/aic.690370415
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    Ignition and extinction of surface and homogeneous oxidation of NH3 and CH4 (1991)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 37 (1991), S. 641-649 
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    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Ignition, extinction and autothermal behavior of surface and homogeneous oxidation reactions of CH4, NH3, and mixed NH3/CH4 fuel systems in air over resistively heated Pt foils was studied in an atmospheric pressure flow reactor. Also examined were the effects of varying fuel concentration on the ignition, extinction, and autothermal surface temperatures. Heterogeneous ignition occurred at ∼200°C for NH3 and at ∼600°C for CH4. The mixed fuel systems exhibited two surface ignitions (∼200°C and ∼600°C), implying a sequential ignition of the two fuels. The effects of removing one of the fuels during autothermal operation gave results consistent with this hypothesis.In homogeneous ignition, two types of flames were observed: a boundary layer flame associated with NH3 systems and an independent flame observed in all systems. Homogeneous ignition of the two fuels and the mixtures occurred at surface temperatures ranging from 1,100°C to 1,600°C and appeared to be dominated by CH4 in the mixed systems. A generic behavior is proposed for homogenous-heterogeneous combustion of single and mixed fuels.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/aic.690370502
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    Pillared clays as a new class of sorbents for gas separation (1991)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 37 (1991), S. 679-686 
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    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: High-surface-area, Zr-pillared, layered clays are synthesized and characterized for their adsorption properties. Although large free interlayer spacings are claimed in the literature (as also found in this work, 14.3 Å), the limiting pore size is the narrow interpillar spacing. The distribution of interpillar spacing is determined by molecular probing and adsorption data along with a theoretical framework available from the literature. Interpillar spacing can be tailored by controlling the number density of pillars inserted during the ion exchange (oligomer inserting) step. The following variables in the ion exchange solution result in lowering the pillar density: higher pH, lower oligomer concentration, and introduction of competitive cations. By changing these variables, peak interpillar spacing is shifted by nearly 2 Å (from 5 to 7 Å). The versatility of pillared clays as sorbents for kinetic separation (i.e., separation based on diffusivity differences) has been demonstrated by the separations of air and xylene isomers.
    Additional Material: 8 Ill.
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    URL: http://dx.doi.org/10.1002/aic.690370506
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    Prediction of gas adsorption in 5a zeolites using Monte Carlo simulation (1991)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 37 (1991), S. 769-779 
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    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 of air in 5A zeolites was studied using Monte Carlo simulations in the grand canonical ensemble (μ, V, T constant). Site-site potentials were used to model the adsorbate-zeolite and adsorbate-adsorbate interactions. The potential model contains one adjustable parameter that was fit to a single experimental isotherm data point. Adsorption isotherms and heats of adsorption were determined for pure argon, oxygen, and nitrogen at 203.15 K, 233.15 K, and 297.15 K from 0.1 bar to 4.0 bar. Multicomponent adsorption isotherms were determined for binary mixtures of oxygen and nitrogen at 203.15 K. The results for the pure-component isotherms are in excellent agreement with experimental data. The results for the heat of adsorption are in good agreement with experimental data for argon and oxygen, but not for nitrogen. The results for multicomponent adsorption isotherms are qualitatively correct; however, the simulation was not able to quantitatively predict mixture data.
    Additional Material: 13 Ill.
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    URL: http://dx.doi.org/10.1002/aic.690370514
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    Isotherm selection for band profile simulations in preparative chromatography (1991)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 37 (1991), S. 836-844 
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    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Equilibrium adsorption data for the N-benzoyl derivatives of D- and L-phenyl alanine in water/propanol solutions have been determined on a chiral-selective stationary phase, bovine serum albumin immobilized on silica. These data are well accounted for by an isotherm equation resulting from the sum of two Langmuir terms. The first term corresponds to the chiral-selective interactions, and the second to the nonselective molecular interactions between the enantiomers and the stationary phase. The individual band profiles of the two enantiomeric amino acids, either pure or in binary mixtures of various compositions, are predicted exactly by an equilibrium dispersive model using this bi-Langmuir isotherm. A classical Langmuir isotherm fails to predict these band profiles, illustrating the importance to collect accurate adsorption data and to use a correct isotherm model when calculating chromatographic band profiles.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/aic.690370606
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    Flow characteristics of waxy crude oils: Application to pipeline design (1991)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 37 (1991), S. 871-885 
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    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Waxy crude oils are highly non-Newtonian materials known to cause handling and pipelining difficulties and whose flow properties are time- and history-dependent. Experimental techniques are described that enable reproducible steady-state flow property data to be obtained from rotational viscometers. The flow properties are shown to depend strongly on the shear rate applied during cooling (shear history effect). This leads to a definable minimum operating point below which flow in a waxy crude oil pipeline would cease. Modified pipeline design techniques are presented for both laminar and turbulent flow at temperatures below the pour point, and it is shown that existing techniques overestimate the flow rate in laminar flow by the order of 100%. The modified design techniques can be used to quantitatively assess the performance of flow improver (pour point depressant) additives under steady-state conditions.
    Additional Material: 17 Ill.
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    URL: http://dx.doi.org/10.1002/aic.690370610
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    Oxidative pyrolysis of methane to higher hydrocarbons: Effects of water in feed (1991)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 37 (1991), S. 915-922 
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    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Direct conversion of methane into higher hydrocarbons (ethane, ethylene, and to small extent C3-4 hydrocarbons) by its partial oxidation with oxygen in the absence of catalyst has been investigated. It was carried out in a quartz flow reactor at atmospheric pressure under nonflame conditions at different temperatures (1,123-1,273 K), CH4/O2 ratios (1.7-9.0), space velocities (500-5,000 h-1), and water concentrations (0.0-80 mol %) in the feed. No coke deposition was observed in the reactor, but there was a formation of small amounts of tarry matter in the reaction at ≥ 1,223 K, particularly for the lower CH4/O2 ratios (≤3.5). The product distribution in the process was strongly influenced by the dilution of feed with N2 or water. Addition of water in the feed was highly beneficial to obtaining higher yield and/or to selectivity for the higher hydrocarbons and suppressing almost completely the formation of tarry matter.
    Additional Material: 10 Ill.
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    Equation for the superficial bubble-phase gas velocity in fluidized beds (1991)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 37 (1991), S. 953-954 
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    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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    URL: http://dx.doi.org/10.1002/aic.690370619
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    Role of AIChE journal in the chemical engineering profession (1991)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 37 (1991), S. 961-961 
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    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
    URL: http://dx.doi.org/10.1002/aic.690370702
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    Comparative analysis of qualitative models when the model changes (1991)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 37 (1991), S. 931-943 
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    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 important application of the recently developed techniques in qualitative mathematical modeling is to qualitatively predict how changes in the operation of chemical units affect their behavior. Weld (1987, 1988a,b) has developed a series of comparative techniques that analyze the effect of perturbations to the parameters of a given qualitative unit model. In this article we demonstrate a system, based on the qualitative process theory of Forbus (1984), which extends comparative analysis in two ways. First, it predicts the effects of changes in the qualitative equations and in parameter values. Secondly, it compares physical descriptions, rather than comparing models directly, and builds and compares the associated models automatically.
    Additional Material: 13 Ill.
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    URL: http://dx.doi.org/10.1002/aic.690370616
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    Correlation method for chemical communication of coal (1991)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 37 (1991), S. 955-957 
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    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690370620
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    Reaction-driven convection in a porous medium (1991)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 37 (1991), S. 963-985 
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    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 onset of three-dimensional reaction-driven convection in a porous medium is investigated using linear stability theory. The geometries investigated include a finite cylinder and a rectangular parallelepipped of arbitrary aspect ratios. The analysis determines, among other things, the likely modes (flow patterns) to emerge first as a function of reaction parameters and aspect ratios. The flow fields corresponding to three-dimensional modes are described in detail. Important qualitative differences are found between reaction-driven convection and the standard Lapwood or Bénard convection due to a temperature gradient applied to the boundaries of the system.The second part of the work examines numerically reaction-driven natural convection in a porous two-dimensional rectangular box. Orthogonal collocation and continuation techniques are used to determine the conduction and convection branches of solutions as a function of the Rayleigh number (Ra), the Frank-Kamenetskii number (δ) and the aspect ratio (α). The convective solutions (streamlines and isotherms) corresponding to primary, secondary and tertiary bifurcations are presented. The effect of natural convection (Ra) on the ignition point (critical δ value) is determined for three different aspect ratios.
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    URL: http://dx.doi.org/10.1002/aic.690370703
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    Dynamics of carbon dioxide sorption on activated-carbon particles (1991)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 37 (1991), S. 1027-1034 
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    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A theoretical model comprising the processes of micropore, macropore and surface diffusion was derived and applied to the dynamics of adsorption of CO2 on a single activated-carbon particle. The effects of a nonlinear isotherm (Langmuir), particle nonisothermality and concentration dependence of the surface diffusivity were also incorporated. The theoretical model was fitted to a preliminary set of adsorption experimental data (two particle sizes, and various temperatures and concentrations) to determine the diffusion coefficients. The validity of the theoretical model was checked by using the model, with fitted diffusivities, to simulate dynamic adsorption curves at conditions different from those of the preliminary fitting data set. These model simulations were found to predict the experimental data in a satisfactory manner.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/aic.690370708
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    Multicomponent adsorption and chromatography with uneven saturation capacities (1991)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 37 (1991), S. 1333-1340 
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    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In chromatographic separations involving elutes with large differences in the molecular size, the adsorption saturation capacities of the elutes may differ because of the differences in the degree of size exclusion. With uneven saturation capacities, isotherm crossovers may occur, which often results in selectivity reversal. In this work, a new multicomponent isotherm has been developed for this kind of system. The isotherm is an extension of the common multicomponent Langmuir isotherm and introduces no or a very limited number of new parameters for its construction. The isotherm crossover conditions have also been derived. Simulations based on a general rate model using the new isotherm have successfully demonstrated the phenomena of peak reversal and crossover of breakthrough curves.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/aic.690370906
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    Contact time distributions in a large fluidized bed (1991)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 37 (1991), S. 1589-1592 
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    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690371017
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    Linear oscillations of a drop in uniform alternating electric fields (1991)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 37 (1991), S. 1601-1606 
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    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Oscillations of a conducting drop immersed in a dielectric fluid in an alternating electric field were modeled to understand the enhancement of transport processes by the electric field. Numerical solutions for oscillation amplitude, velocity distribution, resonant frequency and streamlines were obtained. The effects of viscosity and density on the resonant frequency and the velocity distribution were investigated. It was found that the resonant frequency of viscous fluids was always smaller than the free oscillation frequency of the same droplet. The predicted scanning frequency response curve and the streamlines agree well with the experimental observations.
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    URL: http://dx.doi.org/10.1002/aic.690371102
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    Analysis method of pyrolysis kinetics using modern signal processing techniques (1991)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 37 (1991), S. 1415-1419 
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    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690370914
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  • 93
    Electronic Resource
    Electronic Resource
    Direct numerical simulations of reacting flows in homogeneous turbulence (1991)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 37 (1991), S. 1459-1470 
    Details
    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 direct numerical simulation (DNS) code has been modified to investigate chemically reacting flows in a stationary, homogeneous turbulence. Single and multispecies reactions as well as complicated reaction schemes such as parallel/consecutive reactions are studied. The effects of some parameters are discussed. The numerical data are used to test a simple first-order closure model, proposed by Dutta and Tarbell (1989), for turbulent reacting flows. It is shown that the DNS technique provides us with an effective tool to isolate the effects of different parameters and is likely to be useful for proposing and testing closure models.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690371004
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  • 94
    Electronic Resource
    Electronic Resource
    Turbulent diffusivities in reacting systems (1991)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 37 (1991), S. 1737-1738 
    Details
    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
    URL: http://dx.doi.org/10.1002/aic.690371118
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  • 95
    Electronic Resource
    Electronic Resource
    Evaluating all real roots of nonlinear equations using a global fixed-point homotopy method (1991)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 37 (1991), S. 1749-1752 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690371122
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  • 96
    Electronic Resource
    Electronic Resource
    Explicit runaway criterion for catalytic reactors with transport limitations (1991)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 37 (1991), S. 1780-1788 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Most existing criteria for predicting parametric sensitivity or runaway in a catalytic reactor are based on a single-phase model that does not account for interparticle heat and mass transfer resistances and intraparticle diffusion. Accounting for these effects, the simple criterion \documentclass{article}\pagestyle{empty}\begin{document}$$\frac{E}{{RT_f }}\frac{{(- \Delta H)r(T_f,C_f)}}{{T_f }}\left[{\frac{{d_t }}{{4U}} + \frac{{d_p }}{{6h}}} \right] 〈 0.368f(\phi _0)$$\end{document} defines the boundary of operating conditions, in which a catalytic reactor is insensitive to small perturbations. Here, r(Tf,Cf) is the intrinsic reaction rate at inlet conditions, dt(dp) and U(h) are the diameter of reactor tube (catalyst particle) and heat transfer coefficient between the fluid and tube wall (catalyst particle), respectively. The function f(φ0), where φ0 is the normalized Thiele modulus at inlet conditions, accounts for the effects of intraparticle diffusion. For the common case of equal coolant and feed temperatures, f(φ0) = 1 for φ0 〈 0.5 and f(φ0) = 2 φ0 for φ0〉0.5. The conservatism associated with the above criterion is comparable to the uncertainty involved in determining the parameters of the packed bed.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690371203
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  • 97
    Electronic Resource
    Electronic Resource
    Effect of radiation on the combustion rate in a condensed phase (1991)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 37 (1991), S. 1595-1597 
    Details
    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
    URL: http://dx.doi.org/10.1002/aic.690371019
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  • 98
    Electronic Resource
    Electronic Resource
    Pore size engineering in zeolites. By E. F. Vansant, John Wiley & Sons, Chichester, 1990, 148 pp., $59.95 (1991)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 37 (1991), S. 1905-1905 
    Details
    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
    URL: http://dx.doi.org/10.1002/aic.690371215
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  • 99
    Electronic Resource
    Electronic Resource
    Chemical, quasi-chemical and perturbation theories for associating fluids (1991)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 37 (1991), S. 1875-1894 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Pure fluids and mixtures of species that hydrogen bond behave differently from systems that interact only through dispersion forces. The deviations from classical behavior often are sufficiently large that conventional equations of state and activity models cannot be used without the introduction of large, condition-dependent empirical parameters. Consequently, three different classes of theories have been developed specifically to treat hydrogen-bonding systems. The first is based on the assumption that when molecules hydrogen-bond, they react to form new species and consequently is referred to as “chemical” theory. The second is based on lattice-fluid theory that is used to describe different types of specific interactions and is known as “quasi-chemical” theory. The last is based on the solution of integral equations using a potential function that mimics that of a hydrogen bond. It is shown here that these three approaches give essentially equivalent results. This allows one to relate the parameters in the perturbation theory to the equilibrium constant and hence greatly improves its utility for real systems. All three theories are compared with simulation data.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690371212
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  • 100
    Electronic Resource
    Electronic Resource
    Basic bioreactor design. By Klass van't Reit and Johannes Tramper, Marcel Decker, Inc., New York, 472 pp., $135.00 ($55.0 for orders of 5 or more copies, for classroom use only) (1991)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 37 (1991), S. 1906-1906 
    Details
    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
    URL: http://dx.doi.org/10.1002/aic.690371217
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