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  • 1985-1989  (257)
  • 1955-1959  (1.063)
  • Industrial Chemistry  (1.231)
  • gene expression
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  • 1
    Digitale Medien
    Digitale Medien
    Expression of the genes of interferons and other cytokines in normal and diseased tissues of man (1989)
    Springer
    Cellular and molecular life sciences 45 (1989), S. 526-535 
    Details
    ISSN: 1420-9071
    Schlagwort(e): Interferon ; cytokines ; interleukins ; gene expression ; transcription ; autoimmune ; disease
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Specific interferon genes are transcribed at low levels in the spleen, liver, and peripheral blood leukocytes of normal individuals in the apparent absence of virus infection while other interferon genes remain unexpressed in the same tissues. In contrast, the genes of cytokines such as IL-1, IL-6 and TNF are expressed at relatively high levels in the organs of normal individuals. The level of expression of the IL-1, IL-6 and TNF genes is markedly reduced in the livers of patients with autoimmune liver disease compared to the level of expression in the liver of normal individuals, whereas the expression of interferon genes is similar in both normal and diseased liver, suggesting that a defect in the expression of specific cytokines is associated with severe liver disease.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01990502
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  • 2
    Digitale Medien
    Digitale Medien
    Genetic and tissue-specific variation in the expression of a closely linked murine multigene family on chromosome 15 that encodes salivary and lacrimal proteins (1989)
    Springer
    Biochemical genetics 27 (1989), S. 613-637 
    Details
    ISSN: 1573-4927
    Schlagwort(e): mouse ; salivary protein ; lacrimal protein ; gene expression ; Spt locus ; multigene family
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract The murine submandibular gland (SMG) produces a novel class of highly acidic salivary proteins encoded by one or more highly abundant mRNA transcripts. In inbred mice, these transcripts are encoded by members of a multigene family comprising approximately 8–12 homologues. Most, and probably all, of these homologues are clustered at a new locus near belted (bt) on chromosome 15, which we designateSpt (salivary protein). Although physically closely linked,Spt genes differ in their patterns of expression both in strains of mice and in their tissues. One gene,Spt-1, is expressed at high levels in the SMG of all inbred strains examined. This gene is also expressed at significant levels in the lacrimal gland. A second gene,Spt-2, appears to be present as a single copy in some strains and as two copies in others. This gene is expressed at high levels only in the SMG of those strains carrying two copies, andSpt-2 mRNA is not detectable in the SMG of strains carrying only one copy. In contrast toSpt-1, theSpt-2 gene is not expressed at detectable levels in the lacrimal gland.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00553636
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  • 3
    Digitale Medien
    Digitale Medien
    Genetic and tissue-specific variation in the expression of a closely linked murine multigene family on chromosome 15 that encodes salivary and lacrimal proteins (1989)
    Springer
    Biochemical genetics 27 (1989), S. 613-637 
    Details
    ISSN: 1573-4927
    Schlagwort(e): mouse ; salivary protein ; lacrimal protein ; gene expression ; Spt locus ; multigene family
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract The murine submandibular gland (SMG) produces a novel class of highly acidic salivary proteins encoded by one or more highly abundant mRNA transcripts. In inbred mice, these transcripts are encoded by members of a multigene family comprising approximately 8–12 homologues. Most, and probably all, of these homologues are clustered at a new locus near belted (bt) on chromosome 15, which we designateSpt (salivary protein). Although physically closely linked,Spt genes differ in their patterns of expression both in strains of mice and in their tissues. One gene,Spt-1, is expressed at high levels in the SMG of all inbred strains examined. This gene is also expressed at significant levels in the lacrimal gland. A second gene,Spt-2, appears to be present as a single copy in some strains and as two copies in others. This gene is expressed at high levels only in the SMG of those strains carrying two copies, andSpt-2 mRNA is not detectable in the SMG of strains carrying only one copy. In contrast toSpt-1, theSpt-2 gene is not expressed at detectable levels in the lacrimal gland.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02396156
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  • 4
    Digitale Medien
    Digitale Medien
    Regulation of human and murine complement: Comparison of 5′ structural and functional elements regulating human and murine complement factor B gene expression (1989)
    Springer
    Molecular and cellular biochemistry 89 (1989), S. 1-14 
    Details
    ISSN: 1573-4919
    Schlagwort(e): complement ; factor B ; gene expression ; interferon-ψ ; interleukin-1
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie , Medizin
    Notizen: Abstract The serine protease complement factor B (Bf), an acute phase plasma protein, is a component of the alternative pathway of complement activation. Previous studies revealed that several cytokines including IFN-γ and IL-1 are involved in mediating acute phase Bf expression. To determine the molecular details of Bf expression we isolated, sequenced and characterized the 5′ flanking regions of the human and murine Bf genes. In both species the Bf transcriptional start site in liver was located 〈400 by 3′ to the polyadenylation site of the upstream C2 gene. This upstream intergenic region contained 〉65% nucleotide homology between species. Within this region, an IRS and three heat shock consensus elements were found in the murine sequence in an identical position to that of the human. To examine the functional details of Bf expression, a series of mouse and human Bf promoter - chloramphenicol acetyltransferase (CAT) chimeric gene constructs were transfected into mouse L or human HepG2 cells. Analysis of expression of these fusion gene constructs revealed that 1) cis-acting DNA sequences identified, at least in part, in the 3′ untranslated region of the C2 gene (within the 400 by upstream of the Bf cap site) mediate responsiveness to IL-1 and IFN-γ, 2) the responsiveness to each mediator appears to be conferred by separate upstream regions similar in position and homologous in man and mouse, and 3) the IL-1 responsive region in both species appears to have the characteristics of an enhancer element. The results of this analysis suggest a selective pressure to conserve the intergenic sequence between C2 and Bf genes and that further studies of these sequences will be useful in elucidating mechanisms controlling the acute phase response.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00228274
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  • 5
    Digitale Medien
    Digitale Medien
    Differential early activation of defense-related genes in elicitor-treated parsley cells (1989)
    Springer
    Plant molecular biology 12 (1989), S. 227-234 
    Details
    ISSN: 1573-5028
    Schlagwort(e): differential cDNA screening ; gene expression ; hybrid-select in vitro translation ; nuclear run-off transcription ; RNA blot hybridization
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract A cDNA library from cultured parsley (Petroselinum crispum) cells was differentially screened using labeled run-off transcripts derived from nucleic of elicitor-treated and untreated cells. This resulted in the isolation of 18 independent cDNA families representing putative defense-related genes. All genes are rapidly and transiently activated after elicitor application, but the time courses of transcriptional activity exhibit considerable variations, indicating differences in the mechanisms of gene regulation.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00020507
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  • 6
    Digitale Medien
    Digitale Medien
    A unified matrix hypothesis of DNA-directed morphogenesis, protodynamism and growth control (1989)
    Springer
    Bioscience reports 9 (1989), S. 157-188 
    Details
    ISSN: 1573-4935
    Schlagwort(e): matrix hypothesis ; morphogenesis ; protodynamics ; growth control ; DNA ; genome organisation ; gene expression ; gene regulation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract A theoretical concept is proposed, in order to explain some enigmatic aspects of cellular and molecular biology of eukaryotic organisms. Among these are the C-value paradox of DNA redundancy, the correlation of DNA content and cell size, the disruption of genes at DNA level, the “Chromosome field” data of Lima de Faria (Hereditas 93∶1, 1980), the “quantal mitosis” proposition of Holtzeret al. (Curr. Top. Dev. Biol. 7∶229 1972), the inheritance of morphological patterns, the relations of DNA and chromosome organisation to cellular structure and function, the molecular basis of speciation, etc. The basic proposition of the “Unified Matrix Hypothesis” is that the nuclear DNA has a direct morphogenic function, in addition to its coding function in protein synthesis. This additional genetic information is thought to be largely contained in the non-protein coding transcribed DNA, and in the untranscribed part of the genome.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01115994
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  • 7
    Digitale Medien
    Digitale Medien
    Expression of an active spinach acyl carrier protein-I/protein-A gene fusion (1989)
    Springer
    Plant molecular biology 12 (1989), S. 95-104 
    Details
    ISSN: 1573-5028
    Schlagwort(e): acyl carrier protein ; fatty acid synthesis ; gene expression ; gene fusion ; protein A ; spinach
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract A synthetic gene encoding spinach acyl carrier protein I (ACP-I) was fused to a gene encoding the Fc-binding portion of staphylococcal protein A. This gene fusion, under the control of the λPR promoter, was expressed at high levels in Escherichia coli producing a 42 kDa fusion protein. This fusion protein was phosphopantethenylated in E. coli. In vitro the ACP portion of the fusion protein was able to participate in acyl ACP synthetase reactions, plant malonyl-CoA:ACP transacylase (MCT) reactions, and plant fatty acid synthetase (FAS) reactions. Inhibitory effects of high ACP concentrations on in vitro plant FAS were observed with the unfused ACP-1 but not with the fusion protein. As with unfused ACP-I, the fusion protein was a poor substrate for E. coli FAS reactions. When injected into rabbits, the fusion protein was also able to generate antiserum to spinach ACP-I.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00017452
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  • 8
    Digitale Medien
    Digitale Medien
    cDNA sequence and differential expression of the gene encoding the glutamine synthetase γ polypeptide ofPhaseolus vulgaris L. (1989)
    Springer
    Plant molecular biology 12 (1989), S. 553-565 
    Details
    ISSN: 1573-5028
    Schlagwort(e): cDNA sequence ; gene expression ; glutamine synthetase ; legume-Rhizobium symbiosis ; nitrogen metabolism ; Phaseolus vulgaris L.
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract We report the sequence of an essentially full-length glutamine synthetase (GS) cDNA clone (pcGS-γ1) isolated from a root nodule library ofPhaseolus vulgaris L. The polypeptide encoded by this cDNA has been producedin vitro by transcription/translation and shown to co-migrate on two-dimensional gels with the previously identified major cytosolic GS polypeptide (γ) of nodules. Two previously identified GS cDNA clones, pR-2 and pR-1 (see Gebhardtet al., EMBO J 5: 1429–1435, 1986) have similarly been shown to encode the α and β cytosolic GS polypeptides respectively. An RNase protection technique has been used to analyse specifically and quantitatively the abundance of mRNA related to these three GS cDNAs and to the cDNA (pcGS-δ1) encoding the chloroplast-located GS, during nodulation. Differences in the abundances of these mRNAs at different times suggest that they are not coordinately regulated. Moreover, using this technique mRNA specifically related to pcGS-γ1 was found at high levels in nodules but not in roots or leaves. Surprisingly the expression of this gene is not nodule-specific as previously suggested, as its mRNA was also detected, but at lower levels, in stems, petioles and in green cotyledons. By comparison, mRNA related to a leghaemoglobin gene was detected only in nodules. Comparisons of the relative abundances of the pcGS-γ1 mRNA and the γ polypeptide in different organs and at different stages during nodulation, suggest that the appearance of the γ polypeptide is largely under transcriptional control.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00036969
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  • 9
    Digitale Medien
    Digitale Medien
    Antisense RNA inhibition of β-glucuronidase gene expression in transgenic tobacco plants (1989)
    Springer
    Plant molecular biology 13 (1989), S. 399-409 
    Details
    ISSN: 1573-5028
    Schlagwort(e): antisense RNA ; β-glucuronidase ; tobacco ; transgenic plants ; gene expression
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Antisense RNA was used to specifically inhibit the expression of a GUS gene introduced in a transgenic plant. A tobacco transformant containing a single intact copy of the GUS gene and showing relatively high constitutive levels of GUS activity (GUS+) was re-transformed with an Agrobacterium Ti-derived binary vector containing an antisense version of this reporter gene. The sense and antisense GUS genes were each under the regulation of the CaMV 35S promoter. Re-transformed plants contained 1–5 copies of the antisense construct and all showed a greater than 90% reduction in GUS activity relative to the original GUS+ plant. This reduction in GUS activity correlated closely with the levels of GUS enzyme and steady state GUS mRNA observed in these plants. The relatively low levels of sense and antisense GUS transcripts found in the re-transformed plants may indicate a rapid degradation of the RNA:RNA duplex in the cell.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00015552
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  • 10
    Digitale Medien
    Digitale Medien
    Involvement of Rhizobium leguminosarum nodulation genes in gene expression in pea root hairs (1989)
    Springer
    Plant molecular biology 12 (1989), S. 157-167 
    Details
    ISSN: 1573-5028
    Schlagwort(e): deformation factor ; gene expression ; pea ; Rhizobium leguminosarum ; root hairs
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The mRNA population in pea root hairs was characterized by means of in vitro translation of total root hair RNA followed by 2-dimensional gel electrophoresis of the translation products. Root hairs contain several mRNAs not detectable in total RNA preparations from roots. Most of these root hair-specific mRNAs occur in elongating root hairs at higher levels than in mature root hairs. The expression of some genes in pea root hairs is typically affected by inoculation with Rhizobium leguminosarum. One gene, encoding RH-42, is specifically induced while the expression of another gene, encoding RH-44, is markedly enhanced. Using R. leguminosarum mutants it was shown that the nodC gene is required for the induction and enhancement of expression of the RH-42 and RH-44 genes, respectively, while the Rhizobium chromosomal gene pss1, involved in exopolysaccharide synthesis, is not essential. After induction of the nod genes with apigenin the bacteria excrete into the culture medium a factor that causes root hair deformation. This deformation factor stimulates the expression of the RH-44 gene but does not induce the expression of the gene encoding RH-42.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00020501
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  • 11
    Digitale Medien
    Digitale Medien
    Phytochrome control of multiple transcripts of the phytochrome gene in Pisum sativum (1989)
    Springer
    Plant molecular biology 12 (1989), S. 295-299 
    Details
    ISSN: 1573-5028
    Schlagwort(e): gene expression ; multiple transcripts ; phytochrome ; Pisum sativum ; red/far-red reversible effect
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The reversible effect of red and far-red light on the level of two RNA transcripts of the single-copy phytochrome gene in pea was investigated using the primer extension assay. In dark-grown seedlings, a brief irradiation with red light markedly reduced the level of one of the phytochrome transcripts, RNA1. This red light effect was reversed by subsequent irradiation with far-red light. The other phytochrome transcript, RNA2, was only slightly influenced by light. In light-grown seedlings, a brief irradiation with far-red light increased the content of both RNA1 and RNA2 when the seedlings were transferred from light to darkness. This far-red light effect was reversible by subsequent red light irradiation.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00043206
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  • 12
    Digitale Medien
    Digitale Medien
    Structure and expression of the maize gene encoding the phosphoenolpyruvate carboxylase isozyme involved in C4 photosynthesis (1989)
    Springer
    Plant molecular biology 12 (1989), S. 579-589 
    Details
    ISSN: 1573-5028
    Schlagwort(e): C4 photosynthesis ; gene structure ; gene expression ; genetic variation ; silent substitution ; Zea mays
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract We have determined the structure of the maize (Zea mays L. subsp.mays line B73) nuclear gene encoding the phosphoenolpyruvate (PEP) carboxylase isozyme involved in C4 photosynthesis. The gene is 5.3 kb long and has ten exons that range in size from 85 to 999 bp. The nine introns vary from 97 to 872 bp. The sequence of 663 bp of 5′-flanking and 205 bp of 3′-flanking DNA is reported along with the entire gene sequence. Several short repetitive sequences were found in the 5′-flanking DNA that have characteristics similar to elements important in the light regulation of pea genes encoding the small subunit of ribulose 1,5-bisphosphate carboxylase. In addition, some 5′-flanking sequence similarities were found in a comparison with other light-regulated genes from maize and wheat. The level of DNA sequence variation among different PEP carboxylase alleles is similar to the allelic variation observed for several other maize nuclear genes. The data suggest modern maize variaties have retained much of the genetic variation present in their ancestral forms. Finally, accumulation of transcripts encoding the PEP carboxylase isozyme involved in C4 photosynthesis is quite high in several structures besides leaves, including inner leaf sheaths, tassels and husks. This indicates that expression of this gene is not leaf-specific and may not necessarily be coupled to the development of Kranz anatomy.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00036971
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  • 13
    Digitale Medien
    Digitale Medien
    The bifunctional α-amylase/subtilisin inhibitor of barley: nucleotide sequence and patterns of seed-specific expression (1989)
    Springer
    Plant molecular biology 12 (1989), S. 673-682 
    Details
    ISSN: 1573-5028
    Schlagwort(e): amylase inhibitor ; barley ; cDNA sequence ; gene expression ; hormonal regulation ; protease inhibitor
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract We have cloned and sequenced a full-length cDNA from barley (Hordeum vulgare L.) seeds encoding the bifunctional α-amylase/subtilisin inhibitor (BASI). The nucleotide sequence predicts an open reading frame coding for a protein of 203 amino acids. The first 22 amino acids exhibit the sequence characteristic of a signal peptide, as found in several other plant protease inhibitors. Northern blot hybridization experiments indicate that BASI mRNA accumulation is strictly tissue-specific and is developmentally programmed. BASI mRNA transcripts were only identified in 1) developing starchy endosperm tissue from 14 days after flowering and 2) aleurone tissue of germinating seeds. In this latter tissue, BASI mRNA accumulation is enhanced by abscisic acid and abolished by gibberellic acid. Expression of BASI mRNA was also studied in the lys 3a high-lysine barley mutants Risø No. 1508 and Piggy. These high-lysine barleys show 2–4-fold higher levels as well as prolonged accumulation of BASI mRNA compared to the normal motherline Bomi. This correlates with the increased deposition of BASI protein in lys 3a barley mutants. Genomic blot analysis of barley DNA suggests that there are one or two BASI structural genes per haploid genome. Possible roles of BASI as part of a defence mechanism against precocious germination and pathogens are discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00044158
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  • 14
    Digitale Medien
    Digitale Medien
    Effects of cadmium on gene expression in cadmium-tolerant and cadmium-sensitiveDatura innoxia cells (1989)
    Springer
    Plant molecular biology 12 (1989), S. 487-497 
    Details
    ISSN: 1573-5028
    Schlagwort(e): cadmium ; Datura innoxia ; gene expression ; heat shock ; tolerance
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The effect of Cd on gene expression in suspension cultures of twoDatura innoxia cell lines with differing Cd tolerance was studied.In vivo labeling experiments using [3H] leucine showed that Cd induced the synthesis of a similar range of proteins in both cell lines at a concentration which will kill the sensitive but not the tolerant cells. Corresponding changes in levels of translatable mRNA were also observed. The induction of the synthesis of proteins by Cd was transient since Cd-tolerant cells growing continuously in 250 μM CdCl2 contained a similar set ofin vitro translation products to cells growing in the absence of Cd. Although Cd had a similar effect on gene expression in both cell lines, Cd-tolerant cells possess two abundant mRNAs which are constitutively produced. These mRNAs encode proteins of low molecular weight (about 11 kDa) and are either absent or present at a low level in Cd-sensitive cells. The functions of these proteins are not known but they may be involved in the tolerance mechanism. Two-dimensional gel electrophoresis ofin vitro translation products showed that many of the Cd-induced proteins are also induced by heat shock. A 42°C heat shock resulted in agreater range and more intense induction of translatable mRNAs than 4 h exposure to 250 μM CdCl2. However a subset of mRNAs were induced specifically by Cd while other mRNAs were heat shock-specific. There was no difference in the ability of the two cell lines to tolerate heat shock. This was also reflected by the same pattern of major proteins induced by heat shock in the two cell lines.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00036963
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  • 15
    Digitale Medien
    Digitale Medien
    Expression of Anabaena ferredoxin genes in Escherichia coli (1989)
    Springer
    Plant molecular biology 12 (1989), S. 667-672 
    Details
    ISSN: 1573-5028
    Schlagwort(e): ferredoxin ; gene expression ; heterocyst ; Anabaena 7120 ; Escherichia coli
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The genes for ferredoxin from heterocysts (fdx H) and vegetative cells (pet F) of Anabaena sp. strain 7120 were subcloned into plasmid pUC 18/19. Both genes were expressed in Escherichia coli at high levels (≈10% of total protein). Pet F could be expressed from its own promoter. The ferredoxins were correctly assembled to the holoprotein. Heterocyst ferredoxin was purified from E. coli extracts on a large scale. Its biochemical and biophysical properties were identical to those of the authentic ferredoxin, isolated from Anabaena heterocysts.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00044157
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  • 16
    Digitale Medien
    Digitale Medien
    Isolation, characterization and sequence analysis of a full-length cDNA clone encoding NADH-dependent hydroxypyruvate reductase from cucumber (1989)
    Springer
    Plant molecular biology 13 (1989), S. 139-150 
    Details
    ISSN: 1573-5028
    Schlagwort(e): cDNA ; gene expression ; hydroxypyruvate reductase ; light regulation ; peroxisomal enzyme
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract A full-length cDNA encoding NADH-dependent hydroxypyruvate reductase (HPR), a photorespiratory enzyme localized in leaf peroxisomes, was isolated from a λgt11 cDNA library made by reverse transcription of poly(A)+ RNA from cucumber cotyledons. In vitro transcription and translation of this clone yielded a major polypeptide which was identical in size, 43 kDA, to the product of in vitro translation of cotyledonary poly(A)+ RNA and subsequent immunoprecipitation with HPR antiserum. Escherichia coli cultures transformed with a plasmid construct containing the cDNA insert were induced to express HPR enzyme activity. RNA blot analysis showed that HPR transcript levels rise significantly in the first eight days of light-grown seedling development. This closely resembles the pattern seen for HPR-specific translatable mRNA. DNA blot analysis indicated that a single HPR gene is likely present per haploid genome. Nucleotide sequence analysis revealed an open reading frame of 1146 bases which encodes a polypeptide with a calculated molecular weight of 41.7 kDa. The derived amino acid sequence from this open reading frame is 26% identical and 50% similar to the amino acid sequence of the E. coli enzyme phosphoglycerate dehydrogenase, which catalyzes a similar reaction and functions in a related pathway. Statistical analyses show that this similarity is significant (z〉10). The derived amino acid sequence for HPR also contains the characteristics of an NAD-binding domain.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00016133
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  • 17
    Digitale Medien
    Digitale Medien
    Changes in gene expression in the rat brain induced by Zajdela's ascites hepatoma (1989)
    Springer
    Bulletin of experimental biology and medicine 108 (1989), S. 999-1001 
    Details
    ISSN: 1573-8221
    Schlagwort(e): brain ; gene expression ; mRNA ; transplantable hepatomas
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00839794
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  • 18
    Digitale Medien
    Digitale Medien
    Neurons containing cholecystokinin mRNA in the mammillary region: ontogeny and adult distribution in the rat (1989)
    Springer
    Cellular and molecular neurobiology 9 (1989), S. 281-294 
    Details
    ISSN: 1573-6830
    Schlagwort(e): cholecystokinin ; mammillary region ; development ; gene expression ; hybridization histochemistry
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary 1. The ontogeny and adult distribution of neurons containing cholecystokinin (CCK) mRNA in the premammillary and mammillary nuclei and supramammillary region of the rat brain were studied using hybridization histochemistry. 2. The earliest detection of CCK mRNA in the mammillary region was on E14, followed by a marked increase in transcript levels during the next 4 days, a time during which neurons in this region still divide. During the first 2 weeks of life, few changes in the levels of CCK transcripts were seen, and an adult-like pattern of expression was seen on the twenty-first day of life. 3. Low levels of transcripts were present in numerous neurons located in all divisions of the medial nucleus and in the posterior nucleus known to project ipsilaterally to the anteroventral and anteromedial thalamic nuclei. In contrast, none of the neurons in the lateral nucleus (projecting bilaterally to the anterodorsal thalamic nucleus) had detectable transcripts. 4. Many neurons in the supramammillary nucleus had low, moderate, or high levels of transcripts. Some nearby nuclei (such as the dorsal premammillary nucleus) had smaller numbers of neurons with low levels of CCK mRNA, whereas others (such as the ventral premammillary nucleus) had none.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00713035
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  • 19
    Digitale Medien
    Digitale Medien
    Functional mapping of the activity of the R region in the human T-cell leukemia virus type I long terminal repeat to increase gene expression (1989)
    Springer
    Virus genes 2 (1989), S. 147-155 
    Details
    ISSN: 1572-994X
    Schlagwort(e): BAL31 nuclease ; CAT assay ; gene expression ; HTLV-I ; R region ; 5′ untranslated sequence
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract We previously demonstrated the activity of the R fragment in the long terminal repeat of human T-cell leukemia virus type I for elevation of the level of gene expression. In this study, the fragment was deleted with BAL31 nuclease to determine its functional domain. Series of the shortened R fragments were linked to the simian virus 40 promoter unit, which regulated expression of a reporter gene. Examination with the R fragments deleted from the 5′ and 3′ ends showed that borders of the functional domain were mapped within nucleotide positions 458 to 473 for the 5′ end and nucleotide positions 559 to 594 for the 3′ end, respectively. Thus we conclude that a 136-base-pair fragment corresponding to the second half of the R region was sufficient to allow elevation of the level of gene expression.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00315258
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  • 20
    Digitale Medien
    Digitale Medien
    Selective hydrogenation: Kinetic investigation of 1, 3-cyclo-octadiene and cyclo-octene hydrogenationDedicated to Prof. Dr.-Ing. Hanns Hofmann on the occasion of his 65th birthday (1989)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 12 (1989), S. 45-53 
    Details
    ISSN: 0930-7516
    Schlagwort(e): Chemistry ; Industrial Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The vapour phase hydrogenation of 1,3-cyclo-octadiene (COD) over Pd on alumina has been studied in the gas phase, using a recycle reactor. The dependences of COD hydrogenation rates and those of the consecutive cyclo-octene (COE) hydrogenation on the reaction conditions are well described by a model which takes into account mass transfer in the porous layer of palladium. The kinetics of the COE hydrogenation is of a Langmuir-Hinshelwood type. The hydrogenation of COD is of first order with respect to hydrogen. The reaction order with respect to COD is -0.15. If the catalyst surface is completely covered by COD, the hydrogenation of COE is totally suppressed. This indicates a much stronger adsorption of COD than of COE. Hydrogenation of COE can only occur in the innermost part of the pores when the transport of COD by diffusion is insufficient to supply the entire active surface of the catalyst. This happens if the ratio PH2/PCOD exceeds 2/ϕ2 with ϕ being the Thiele's modulus. This relationship permits a simple evaluation of the effective diffusion coefficient in the porous Pd-layer.
    Zusätzliches Material: 14 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/ceat.270120109
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  • 21
    Digitale Medien
    Digitale Medien
    Advances in modelling and design of multitubular fixed-bed reactorsII. A Mathematical Model of the Cocurrent Multitubular Reactor System (1989)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 12 (1989), S. 170-175 
    Details
    ISSN: 0930-7516
    Schlagwort(e): Chemistry ; Industrial Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: This paper presents a method mathematical modelling of cocurrent multitubular fixed-bed reactors. The method is adapted to the most widespread type of industrial reactor design, i.e. the system fitted with disk-and-doughnut baffles. The proposed model makes it possible to estimate the influence of non-uniformity of the heat carrier flow on the reactor characteristics, taking into account the coolant streams by-passing via the tube-to-baffle clearances. Based on the model, the effect of the operating parameters as well as of some more important geometrical parameters of the reactor on an exemplary highly exothermic process of partial benzene oxidation to maleic anhydride is discussed.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/ceat.270120123
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  • 22
    Digitale Medien
    Digitale Medien
    A new model of the effect of stirring intensity on the rate of secondary nucleationPaper presented at the Anual Meeting of the “GVC-Fachausschuß Kristallisation”, The Hague, March 10 to 12, 1986. (1989)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 12 (1989), S. 137-146 
    Details
    ISSN: 0930-7516
    Schlagwort(e): Chemistry ; Industrial Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Secondary nucleation in industrial crystallizers depends on both supersaturation and mechanical stress by stirring. Most models which consider mechanical stress assume that nucleation is proprotional to the energy transferred to the crystals during collisions. This is not based on any physical relationship and, in addition, the models do not satisfactorily reproduce the experimental results. Own model, based on the theory of Hertz/Huber, which accounts for the stress of the crystals caused by impact, gave better results. This well-known and proven theory allows the calculation of the volume abraded during collisions between crystals and stirrer or walls. Introducing a nucleate efficienncy, the effect of mechanical stress on the rate of secondary nucleation, due to stirring intensity and crystallizer size, can be determined.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/ceat.270120119
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  • 23
    Digitale Medien
    Digitale Medien
    Effects of turbulence on heat and mass transfer in stagnation flowsPaper presented at the “Jahrestreffen der Verfahrens-Ingenieure”, Freiburg, September 30 to October 2, 1987.Dedicated to Professor Dr. Josef Kestin on the occasion of his 75th birthday (1989)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 12 (1989), S. 176-187 
    Details
    ISSN: 0930-7516
    Schlagwort(e): Chemistry ; Industrial Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The influence of turbulence on local heat and mass transfer is systematically analyzed. Essential prerequisite is the availability of measurement methods, based on convective mass transfer, which allow the visualization of heat and mass transfer distributions. The results show that, even at low turbulence intensities, the flow and transport phenomena are decisively influenced by the specific design of turbulence grids and the orientation of the grid wires with respect to the stagnation line. Thereby, two different flow mechanisms occur which may interact. The anisotropy of grid turbulence leads to the “wire-gap effect” depending on the actual position of the grid wires in relation to the stagnation line. The other mechanism is based on the wavy wake velocity distribution behind screens and grid which, in conjunction with the centrifugal instability of stagnation flows, may lead to longitudinal vortices. The results indicate why turbulence has not been sufficiently considered in the available (semi-) empirical correlations. Information needed for an accurate prediction of heat and mass transfer in turbulence flows is discussed.
    Zusätzliches Material: 15 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/ceat.270120124
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  • 24
    Digitale Medien
    Digitale Medien
    Reduction of energy requirements in distillationExtended version of a paper presented at the “Jahrestreffen der Verfahrens-Ingenieure”, Freiburg, September 30 to October 2, 1987. (1989)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 12 (1989), S. 163-169 
    Details
    ISSN: 0930-7516
    Schlagwort(e): Chemistry ; Industrial Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Distillation has been, up to now, the standard method for separating fluid mixtures in the process industry and the consensus is that it will remain so for years to come. The only disadvantage of distillation is its high energy requirement. In the following, it will be demonstrated on the example of an ideal ternary mixture, how the energy requirement of distillation process can be reduced. Very effective are some modifications of single columns, optimization of column sequences and direct or indirect column coupling. It will be shown that, just by column coupling, the energy requirement can be reduced to a third.
    Zusätzliches Material: 15 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/ceat.270120122
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  • 25
    Digitale Medien
    Digitale Medien
    Venturi scrubber calculation and optimization (1989)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 12 (1989), S. 188-195 
    Details
    ISSN: 0930-7516
    Schlagwort(e): Chemistry ; Industrial Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Collection efficiency and pressure loss of a venturi scrubber can usually be determined from the calculation models of Barth and Calvert. However, this only leads to reasonable results if the droplets are uniformly distributed throughout each cross-section of the washing zone. In this work, a two-zone models is developed which allows the calculation of the venturi scrubber at operating conditions with a non-uniform droplet distribution. The scrubber geometry is also taken into account. A venturi scrubber was developed on the basis of this new model. Its energy consumption is significantly lower than the well-Known optimum characteristic of Wicke and Holzer. For ideal operating conditions, a new optimum characteristic is given which should be the aim of future optimizations.
    Zusätzliches Material: 17 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/ceat.270120125
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  • 26
    Digitale Medien
    Digitale Medien
    Model concept of floc disintegration in centrifugal fields (1989)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 12 (1989), S. 200-204 
    Details
    ISSN: 0930-7516
    Schlagwort(e): Chemistry ; Industrial Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: A model of floc destruction resulting form mass forces in a centrifugal field is postulated and its validity examined. This model is to be regarded as a supplement to the existing shear-loading disagglomeration models. In order to verify this additional floc disintegration mechanism, appropriate investigations were carried out with flocculated suspensions of silica and Hamburg dock sludge. As a result, in addition to floc disintegration by shear forces within a turbulent flow and in the centrifuge inlet, the existence of another mechanism was demonstrated. This consists in the floc destruction in a centrifugal field where particles in excess of a certain size, or specifically heavier components, are preferentially torn out of the floc. This floc disintegration by mass forces can lead to a classification effect in centrifuges which also subject the flocs to instant high centrifugal forces.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/ceat.270120127
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  • 27
    Digitale Medien
    Digitale Medien
    Mass transfer and chemical reaction in fluid two-phase systemsPresented in part at the 21th meeting of the Dechema-Arbeitsausschuß “Technische Reaktionen” together with the GVC-Fachausschuß “Technische Reaktionsführung” in Aronoldsheim/Taunus, 10-11th February 1982. (1989)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 12 (1989), S. 195-199 
    Details
    ISSN: 0930-7516
    Schlagwort(e): Chemistry ; Industrial Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Steady-state concentrations of the transferred reactant in the bulk phase and the non-flowing diffusion boundary layer of an isothermal, isobaric two-phase reactor with an irreversible first-order reaction and constant composition of one phase.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/ceat.270120126
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  • 28
    Digitale Medien
    Digitale Medien
    Measurement of aeration capacity of fermenters (1989)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 12 (1989), S. 213-217 
    Details
    ISSN: 0930-7516
    Schlagwort(e): Chemistry ; Industrial Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Important aspects of K1a measurement in agitated aerated vessels are briefly characterized from the standpoint of reliability of the measured data. An analysis of the shortcomings of dynamic methods for measuring the K1a is given. A new modification of the dynamic method is proposed, which excludes these inadequacies through a special experimental arrangement. This was verified by comparing the data with those obtained by an independent steady-state method. The new method can serve as a standard of reference, suitable for testing newly developed methods for K1a measurement. The initial response method was tested in this way in non-coalescent liquids, and shown to lead to errors of the order of hundreds of percent. K1a values obtained with the initial response method were found to depend strongly on the probe's location in the vessel.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/ceat.270120129
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  • 29
    Digitale Medien
    Digitale Medien
    Characterization of mixing and residence time distributions in nozzle-type reactors (1989)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 12 (1989), S. 262-269 
    Details
    ISSN: 0930-7516
    Schlagwort(e): Chemistry ; Industrial Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Studies of flow characteristics and residence time distribution, (RTD), have been undertaken in a range of geometrically similar, laboratory nozzle-type reactors. High-speed cine-photography was employed to record the complex phenomena of liquid mixing in the reactor and also to record on film the colour of an injected tracer solution leaving in the effluent. A novel atomic absorption spectrophotometric (AAS) technique was applied to transform the results of the latter film into response curves. This technique provide detailed quantitative data on the residence time distributions (RTD) for different feed rates. A multiparameter model, comprising a network of CSTR's and plug flows, was developed to simulate the experimental response data. Good agreement was obtained between model predictions and experimental results. The experimental technique and theoretical approach are recommended for analyzing the flow patterns and mixing mechanisms in such reactors.
    Zusätzliches Material: 13 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/ceat.270120136
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  • 30
    Digitale Medien
    Digitale Medien
    Streamline-upwind/Petrov-galerkin finite element methods in polymer processing (1989)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 12 (1989), S. 269-273 
    Details
    ISSN: 0930-7516
    Schlagwort(e): Chemistry ; Industrial Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/ceat.270120137
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  • 31
    Digitale Medien
    Digitale Medien
    Vapour-liquid equilibria of hydrogen/coal liquid and methane/coal liquid systems at elevated temperatures and pressures (1989)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 12 (1989), S. 280-288 
    Details
    ISSN: 0930-7516
    Schlagwort(e): Chemistry ; Industrial Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: A cubic equation of state is modified in such a way that prediction of PVT data from 40 model compounds, typical of coal oil, becomes possible with an absolute mean deviation of less than 2% for saturated liquid volumes and vapour pressures 〉 1 bar. Additional correlations for binary interaction parameters are obtained by an optimization procedure using vapour-liquid euilibrium (VLE) data from known heavy hydrocarbon liquid/light gas systems. When the modified equation is applied to coal-derived liquids, only specific gravity and boiling analysis data of the coal liquids are required, primarily in order to determine the equation-of-state parameters. The proposed equation is shown to allow a good prediction of VLE data for systems consisting of wide-boiling-range coal oils and light gases. Experimental values were obtained at elevated temperatures and pressures with a circulation flow apparatus.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/ceat.270120139
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  • 32
    Digitale Medien
    Digitale Medien
    Heat transfer enhancement in fin-plate heat exchangers by wing type vortex generatorsDedicated to Professor Dr. Klaus Gersten on the occasion of his birthday. (1989)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 12 (1989), S. 288-294 
    Details
    ISSN: 0930-7516
    Schlagwort(e): Chemistry ; Industrial Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Heat transfer and fluid mechanical data were computed for laminar channel flows containing strong longitudinal vortex pairs. The strong vortices are generated by thin delta wings and delta winglet pairs of low aspect ratios and large angles of attack. These wings are attached to the channel walls. The data show that longitudinal vortices cause high local peaks in heat transfer and marked increases in the overall channel heat transfer. These increases occur over a wide region of channel wall, compared to the vortex generating wing area. The results are of special interest for compact heat exchangers. The heat transfer enhancement allows a considerable reduction in the heat transfer area which, in turn, reduces the manufacturing and operating costs.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/ceat.270120140
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  • 33
    Digitale Medien
    Digitale Medien
    Fluid dynamic description of jet-loop reactors in multiphase operationModified version of a paper presented by K.H. Tebel at the “Jahrestreffen der Verfahrens-Ingenieure”, Strasbourg, September 17 to 19, 1986. (1989)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 12 (1989), S. 274-280 
    Details
    ISSN: 0930-7516
    Schlagwort(e): Chemistry ; Industrial Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: A superposition of simple physical equations allows a satisfactory, comprehensive fluid dynamic description of jet-loop reactors in multiphase operation up to a dispersed phase hold-up of 15%. In the case of higher concentrations, there are further interactions which are not yet included in the model description. Apart from the drag coefficient of the single-phase jet loop, information on the particle swarm behaviour, i.e. on the slip velocity of the dispersed phase is required. Explicit formulation of the influence of the relevant geometrical parameters permits a reliable scale-up without additional adaptation parameters.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/ceat.270120138
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  • 34
    Digitale Medien
    Digitale Medien
    Incorporation of gradient into random search optimizationPresented at the Second Canadian-German Workshop on Chemical Engineering Mathematics, Bad Honnef, Fr Germany, May 30-June 2, 1988. (1989)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 12 (1989), S. 309-318 
    Details
    ISSN: 0930-7516
    Schlagwort(e): Chemistry ; Industrial Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: To improve the rate of convergence of random search optimization procedures, the incorporation of a gradient-oriented one-dimensional search is investigated. With this modification to the random search procedure based on uniform sampling and region contraction [1], convergence to within 0.01% of the global optimum was obtained substantially faster for typical chemical engineering problems. It was also found that the reliability of obtaining the global optimum was improved.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/ceat.270120143
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  • 35
    Digitale Medien
    Digitale Medien
    Particle collection in small laboratory cyclones as a basis for the design of large-scale cyclonesPaper presented by H. Büttner at the “Jahrestreffen der Verfahrens-Ingenieure”, Freiburg September 30 to October 2, 1987. (1989)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 12 (1989), S. 295-301 
    Details
    ISSN: 0930-7516
    Schlagwort(e): Chemistry ; Industrial Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Grade efficiencies must be measured in order to characterize particle collection in cyclones. For real, irregularly shaped partcles, the grade efficiencies depend on the shape and orientation of the particles and the flow around them. Therefore, the collection characteristics of cyclones should be defined in relation to spherical particles. Deviations occurring on the use of real, irregularly shaped dusts can then be attributed to a material influence. A fast and accurate measuring technique to determine the collection characteristic for spherical particles is described, followed by the presentation of results of extensive investigations on small model cyclones. A similarity relationship is presented. The validity of this relationship was confirmed by investigations with similar, larger cyclones.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/ceat.270120141
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  • 36
    Digitale Medien
    Digitale Medien
    Leakage rates of refrigerants through cracksPaper presented by F. Westphal at the European Two-Phase Flow Group Meeting, Université Catholique de Louvain, Brussels, May 30 to June 1, 1988. (1989)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 12 (1989), S. 301-308 
    Details
    ISSN: 0930-7516
    Schlagwort(e): Chemistry ; Industrial Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: An independent preliminary mechanistic prediction method for leakage rates through small slit-shaped through-wall cracks, based on coupled pressure drop and (critical) mass flux calculation is presented. The predictions are verified against initially subcooled liquid refrigerants and water data collected during experiments in real and model cracks in a wide range of parameters. The achieved accuracy of prediction is already comparable to that of the experimental results. Further model modifications are put forward.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/ceat.270120142
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  • 37
    Digitale Medien
    Digitale Medien
    Parameter estimation from integral Mars-van Krevelen type of kinetic data of a reaction networkDedicated to Professor Dr. Horst Langemann on the occasion of his 60th birthday (1989)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 12 (1989), S. 11-14 
    Details
    ISSN: 0930-7516
    Schlagwort(e): Chemistry ; Industrial Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/ceat.270120103
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  • 38
    Digitale Medien
    Digitale Medien
    Micromixing limits in an MSMPR crystallizer (1989)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 12 (1989), S. 1-11 
    Details
    ISSN: 0930-7516
    Schlagwort(e): Chemistry ; Industrial Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The effect of micromixing limits on a process of crystallization in an MSMPR crystallizer is studied with respect to power law growth and nucleation kinetics. Three limiting cases corresponding to maximum mixedness and complete segregation in an MSMPR crystallizer and plug flow configuration were analyzed for processes in which supersaturation is generated by conventional techniques. The sensitivity of these three limiting cases to the supersaturation generation term in each mode of operation was investigated using several numerical examples. The study demonstrates the effects of mixing on the overall crystallizer performance and, in particular, the enormous micromixing influence at high supersaturation generation rates. The difference in the product CSD arise from the variations of supersaturation profiles experienced by the elementary volumes throughout their sojourn. Characterization of mixing in a real crystallizer at some intermediate levels is emphasized with the aid of relevant industrial examples.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/ceat.270120102
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  • 39
    Digitale Medien
    Digitale Medien
    Coupled simulation of heat transfer and reaction in a steam reforming furnaceDedicated to Professor Dr. Hanns Hofmann on the occasion of his 65th birthday (1989)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 12 (1989), S. 20-26 
    Details
    ISSN: 0930-7516
    Schlagwort(e): Chemistry ; Industrial Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: For design and simulation of chemical process furnaces in accordance with present-day standards, the temperature distributions in the firebox and in the reactors must be generated simultaneously. This calls for coupling of the simulations of the firebox and of the reactor. For the calculation of heat transfer in the firebox, a generalized furnace simulations program, based on the zone method, is applied. Monte Carlo simulation techniques are used to determine the view factors. The location of the burners is explicitly accounted for. Absorption and emission of radiation by the flue gas are calculated by considering band contributions for carbon dioxide and water. For the simulation of the steam reforming reactors, a one-dimensional heterogeneous model, which accounts for the presence of intraparticle partial pressure gradients, is used. The simulated temperature distribution in the furnace is in excellent agreement with industrial results, as is the simulated product distribution.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/ceat.270120105
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  • 40
    Digitale Medien
    Digitale Medien
    Performance of an RTL contactor for gas-liquid systems: Effective interfacial area and volumetric mass transfer coefficient by oxidation of sodium sulphite solution (1989)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 12 (1989), S. 15-19 
    Details
    ISSN: 0930-7516
    Schlagwort(e): Chemistry ; Industrial Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Effective interfacial area a and volumetric liquid-side mass transfer coefficient kLa of an RTL contactor were obtained at different stirring speeds by absorption of oxygen from air into 0.8 kmol/m3 sodium sulphite solution, in the presence of Co++ ions. The values of a and kLa ranged from 80 to 150 m2/m3 and 0.0003 to 0.00053 s-1, respectively, when stirrer speed was increased from 8 to 40 rpm. When kL alone was evaluated, it was found to be practically constant, irrespective of stirring speed.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/ceat.270120104
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  • 41
    Digitale Medien
    Digitale Medien
    IR study of chlorination of alumina employing mixtures of gaseous chlorine and carbon monoxideDedicated to Professor Dr.-Ing. Hanns Hofmann on the occasion of his 65th birthday (1989)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 12 (1989), S. 27-32 
    Details
    ISSN: 0930-7516
    Schlagwort(e): Chemistry ; Industrial Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The chlorination of an alumina with BET surface area of 100 m2/g has been studied in situ by transmission IR measurements at about 670 K. The chlorinating gases consisting of Cl2 and CO were employed individually and in equimolar proportion. The IR results do not reveal the presence of a phosgene surface species which could support the only mechanism proposed so far to explain the chlorination. A detailed alternative reaction mechanism is suggested for the high temperature chlorination reaction, taking into account the IR results, together with the known electron donor-acceptor properties of the activated alumina and the reaction gases: Cl2 molecules accept electrons from oxide ions with a lower coordination number on the alumina surface, leading to the formation of Cl-and Oad. While Cl- yields AlCl3, Oad reacts further with CO producing CO2.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/ceat.270120106
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  • 42
    Digitale Medien
    Digitale Medien
    Heat transfer to submerged surfaces in coarse-grained pressurized fluidized beds and fixed bedsPaper presented by J. Schweinzer at the “Jahrestreffen der Verfahrens-Ingenieure”, Freiburg, September 30 to October 2, 1987. (1989)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 12 (1989), S. 38-44 
    Details
    ISSN: 0930-7516
    Schlagwort(e): Chemistry ; Industrial Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: This contribution reports on the theory underlying a uniform representation of heat transfer to submerged surfaces in fixed bed reactors and of gas convective part of heat transfer in fluidized beds with coarse-grained bulk solids and/or at elevated pressure. Based on an analysis of the pressure drop behaviour of fixed bed percolation at different gas pressures and with different bulk solids, a new dimensionless pressure drop parameter was developed. Fixed bed heat transfer data are very well correlated by this new dimensionless number. As soon as fluid throughput is in excess of minimum fluidization velocity, the pressure drop parameter transforms into the well-known Archimedes number. These two dimensionless numbers are connected by the condition of equilibrium for pressure drop and mass of practices in a fluidized bed. This equilibrium is fulfilled as soon as fluidization commences. Up to now, the Archimedes number has been generally accepted as the significant parameter, determining the gas convective part of heat transfer in fluidized beds; however, without any physical interpretation of this parameter. Introduction of the pressure drop number, which is consistent with the Archimedes number, reduces the heat transfer behaviour to pressure drop characteristics. The usefulness of this concept is proven by the comparison of experimental results and prediction.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/ceat.270120108
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  • 43
    Digitale Medien
    Digitale Medien
    Reversible absorption of nitric oxide in low volatile organic liquids containing cupric halides (1989)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 12 (1989), S. 33-37 
    Details
    ISSN: 0930-7516
    Schlagwort(e): Chemistry ; Industrial Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The absorption of nitric oxide (NO) in phosphoric acid esters and polyethylene glycol ethers which contain cupric halides has been investigated. Due to high solubility of cupric halides and high equilibrium constants of formed nitrosyl complexes, the effective solubility of nitric oxide can be enhanced to about 100-fold its solubility in the salt-free organic liquid which itself amounts to only about 5-fold the NO-solubility in water. Calculations taking into account flue gas conditions indicate that the required gas-liquid ratio in industrial absorption processes will lie in the normal range of flue gas scrubbing processes, namely in the region of 400:1 to 1000:1 in volume. Thus, such a reversible absorption process could a viable alternative to SCR-processes in flue gas denitrification.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/ceat.270120107
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  • 44
    Digitale Medien
    Digitale Medien
    Increase in viscosity and its influence on polymerization processesDedicated to Prof. Dr. Heinz Gerrens on the occasion of his 65th birthday (1989)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 12 (1989), S. 71-87 
    Details
    ISSN: 0930-7516
    Schlagwort(e): Chemistry ; Industrial Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: In the course of polymerization in homogeneous systems, the viscosity of the reaction mass increases by several orders of magnitude. The viscosity increase is affected by reaction conditions, concentration and properties of the formed polymer. Empirical correlations for homogeneous and heterogeneous polymerizations are given. Viscosity significantly affects the polymerization kinetics as well as heat, mass and momentum balances of the polymerization reactor. The influence of viscosity and its increase on conductive heat transfer, stirrer power input and cooling capacity, molecular diffusion and mass transfer coefficients, mixing time and residence time distribution in homogeneous and heterogeneous polymerizations in stirred tank and tubular reactors is reviewed.
    Zusätzliches Material: 16 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/ceat.270120112
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  • 45
    Digitale Medien
    Digitale Medien
    The pressure ratio of critical two-phase flowsDedicated to Professor Dr. h.c. Dr.-Ing. Heinz Brauer on the occasion of his 65th birthday (1989)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 12 (1989), S. 89-96 
    Details
    ISSN: 0930-7516
    Schlagwort(e): Chemistry ; Industrial Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Depressurization of a pressure vessel, containing a liquid or a gas is limited by the maximum possible mass flux. This flux occurs at a certain drop in pressure. The ratio of ambient pressure to that inside the vessel must be less than a certain critical value. The critical pressure ratio depends on the thermodynamic state of the fluid inside the vessel and on the geometry of the outlet cross-section. The outlet can be a pipeline, a safety valve or a rupture disk. The results of known theoretical and experimental work are presented. In previous experiments, saturated liquids, two-phase flows or pure vapours were examined. In order to predict the critical pressure ratio, certain assumptions are necessary. These are derived for three well-defined cross-sections of the vessel outlet.
    Zusätzliches Material: 17 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/ceat.270120113
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  • 46
    Digitale Medien
    Digitale Medien
    Effects of pretreatments on semi-continuous anaerobic digestion of wheat straw (1989)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 12 (1989), S. 96-102 
    Details
    ISSN: 0930-7516
    Schlagwort(e): Chemistry ; Industrial Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The effects of alkali treatment, nitrogen supplement and hydraulic retention time on methane production rate from semi-continuous anaerobic digestion of 5% wheat straw-water mixtures were investigated. The experiments were carried out in laboratory scale fermenters, fed with 1 1 of basic, alkali treated and nitrogen supplemented 5% wheat straw-water mixtures, respectively, and maintained at 55 °C. Digestion experiments were performed for hydraulic retention times of 8, 10 and 15 days. The amount and composition of produced gas were measured until steady state was attained in each run. The steady-state methane production rates were found to increase with hydraulic retention time and with the type of slurry in the following order; basic, nitrogen supplemented and alkali treated slurry. Data obtained from the experiments were employed to determine the kinetics of methane production from anaerobic digestion of wheat straw, for the assessment of pretreatment effects on process kinetics. The predicted methane production rates were found to be in a reasonably good agreement with the measurements.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/ceat.270120114
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  • 47
    Digitale Medien
    Digitale Medien
    Simulation of sintering of model supported metal catalysts (1989)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 12 (1989), S. 103-109 
    Details
    ISSN: 0930-7516
    Schlagwort(e): Chemistry ; Industrial Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: During the past decade, the sintering of model supported metal catalysts, i.e. catalysts consisting of metal deposited on very thin and flat oxide films, has been intensively investigated by transmission electron microscopy. In the current paper, a mathematical model, based on an atomic migration mechanism, for the sintering of these catalysts is presented. The predictions of the model, based on Monte Carlo simulations, are in very good agreement with the experimental observations, i.e. phenomena such as ‘apparent’ particle migration, splitting and neck formation between particles are predicated by the model.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/ceat.270120115
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  • 48
    Digitale Medien
    Digitale Medien
    Dispersion behaviour of droplets in circular loop reactors (1989)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 12 (1989), S. 205-212 
    Details
    ISSN: 0930-7516
    Schlagwort(e): Chemistry ; Industrial Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: A circular loop reactor was built for application to a heterogeneous liquid-liquid reaction. In order to investigate the dispersion behaviour of droplets in the reactor, basic experiments were performed using a number of liquid-liquid dispersions. Droplets discharged form the impeller region were found to grow due to coalescence in the circulation region. Mean droplet diameter decreased exponentially with elapsing time. An expression correlating the steady-state mean droplet diameter with the operating conditions was derived. Moreover, the transition time required for the droplet diameter to reach the equilibrium value was determined and correlated with the operating conditions.
    Zusätzliches Material: 12 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/ceat.270120128
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  • 49
    Digitale Medien
    Digitale Medien
    The contradiction in the theory of desorption phenomena: A new interpretation of the classical concept for its avoidance (1989)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 12 (1989), S. 218-225 
    Details
    ISSN: 0930-7516
    Schlagwort(e): Chemistry ; Industrial Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Most chemical engineers presently accept that the mass transfer rate in desorption from the solid to the gas phase or from the liquid to the gas phase is accelerated with increasing temperature in the liquid or the solid phase, or increasing partial pressure of inert gas in the gas phase, and/or decreasing total system pressure in the gas phase. Nevertheless, many reports about such mass transfer are still based on the former concept, which completely contradicts the actual phenomena mentioned above. Here, we discuss the contradiction and suggest a way of resolving it in terms of diffusion theory.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/ceat.270120130
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  • 50
    Digitale Medien
    Digitale Medien
    Thermally stabilized combustionPaper presented at the “Jahrestreffen der Verfahrens-Ingenieure”, Hannover, September 21 to 23, 1988. (1989)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 12 (1989), S. 249-254 
    Details
    ISSN: 0930-7516
    Schlagwort(e): Chemistry ; Industrial Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Thermally stabilized combustion has a number of unique characteristics which permit the generation of steam or other forms of process energy from the heat of combustion of a gaseous or clean liquid fuel in remarkably compact, integrated apparatus while truly minimizing the concentrations of NOx, CO and unburnt fuel in the effluent. These characteristics, which have been identified by a long-range program of research, are described and the advantages and limitations of this process are discussed.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/ceat.270120134
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  • 51
    Digitale Medien
    Digitale Medien
    Heat and mass transfer during condensation of steam in the presence of air at pressures of up to 21 bar (1989)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 12 (1989), S. 235-244 
    Details
    ISSN: 0930-7516
    Schlagwort(e): Chemistry ; Industrial Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Film theory under consideration of one-sided diffusion is a satisfactory basis for the calculation of vapour condensation from a flowing turbulent mixture with non-condensable gases. At atmospheric pressure and low condensate flow rates, coefficient equations for smooth tubes are used as a rule. At higher pressures and thus, at higher temperatures and gas densities, there are additional parameters. For instance, non-ideal behaviour of the gas phase or the surface roughness affects the condensation process. These parameters were examined in a test plant under variation of pressure, steam concentration and temperature in a vapour/air mixture. At pressures of up to 21 bar, the Reynolds number of the gaseous phase reaches a maximum value of 128 000 and of 720 for the condensed phase. After description of the test facility, the experimental results are explained and discussed. It is shown that the experimental results are not in a good agreement with the common calculating methods. Taking into account the non-ideal behaviour of the steam/air mixture and the roughness of condensate surface by using a friction factor ξr, all the results could be calculated with an accuracy of ± 20%. This was achived with a modification of the coefficient equation of Gnielinski [1] and by using the equation of Andreussi [2] for the friction factor of a cocurrent annular flow. With respect to one-sided diffusion, the film theory is still applicable. The described method for the determination of local transfer coefficients includes the common calculating method. It represents an extension of the general validity of the film theory.
    Zusätzliches Material: 15 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/ceat.270120132
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  • 52
    Digitale Medien
    Digitale Medien
    Influence of turbulence on transient premixed flame propagation inside closed vessels (1989)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 12 (1989), S. 226-233 
    Details
    ISSN: 0930-7516
    Schlagwort(e): Chemistry ; Industrial Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The explosion behaviour of CH4/air mixtures inside a closed 0.065 m3 spherical and a 1 m3 cylindrical vessel was investigated to determine the effect of turbulence on the structure and propagation rate of transient turbulent flames for different initial turbulence levels generated by 4 ventilators installed inside the equipment. Laser-Doppler and hot wire anemometry were used to measure the turbulent motion. It was found that fairly uniform turbulence could be achieved in the central zones of the vessels and that the RMS-values of flow velocity were proportional to the ventilator speed. The evaluation of burning velocity from the pressure/time records showed that, starting from an initial burning velocity which depends on the initial turbulence level, the flame accelerates as a result of pressure, temperature and turbulence effects. Maximum burning velocity coincides with the inflexion point of the pressure/time curve, and is followed by a rapid deceleration of the flame front. A linear relationship between burning velocity and measured RMS-velocity is recognized in the observed range of RMS-values.
    Zusätzliches Material: 13 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/ceat.270120131
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  • 53
    Digitale Medien
    Digitale Medien
    Study of mass transfer in a centrifugal film apparatus (1989)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 12 (1989), S. 245-248 
    Details
    ISSN: 0930-7516
    Schlagwort(e): Chemistry ; Industrial Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Mass transfer data are presented for absorption of oxygen in a centrifugal film apparatus. The apparatus was designed to exclude the formation of foam by gas dispersion in liquid. Cells and micro-organisms are not subjected to high shear stress. Therefore, this equipment can be applied in fermentation processes. In the present work, experimental data and correlations were obtained on splitting of the liquid film and oxygen absorption into the film through a spiral ridge formed on the conical surface. The performance of the apparatus is found to be equivalent to those of other types of absorbers.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/ceat.270120133
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  • 54
    Digitale Medien
    Digitale Medien
    Porosity and permeametry at sub-atmospheric pressures (1989)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 12 (1989), S. 255-261 
    Details
    ISSN: 0930-7516
    Schlagwort(e): Chemistry ; Industrial Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The Carman-Kozeny equation is applicable in the viscous flow regime but, as the powder becomes finer, this equation fails. The controlling factor is the ratio of the hydraulic diameter to the mean free path of gas molecules (rH/λ) and, as this approaches unity, “slip flow” occurs. This effect increases with (a) increasing fineness, i.e. rH reduced, (b) decreasing porosity, i.e. rH reduced, and (c) decreasing pressure, i.e. λ increased. In order to account for the enhanced flow arising as a result of this failure, a second term is introduced into the equation and this includes an unknown “constant” (δK0/K), the coefficient of slip. It was considered probable that this so-called constant was a function of (rH/λ), and an attempt was made to investigate this relationship.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/ceat.270120135
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  • 55
    Digitale Medien
    Digitale Medien
    A new load cell for measuring normal and shear stresses (1989)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 12 (1989), S. 318-323 
    Details
    ISSN: 0930-7516
    Schlagwort(e): Chemistry ; Industrial Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: A special stress measuring device for determining the normal and shear stresses acting on silo walls was developed and tested. The load cell can be used for measuring simultaneously the normal stress as well as the intensity and direction of the shear stress.
    Zusätzliches Material: 16 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/ceat.270120144
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  • 56
    Digitale Medien
    Digitale Medien
    Heat transfer to liquids and suspensions in agitated narrow vesselsPaper presented by D.-H. Frobese at the “Jahrestreffen der Verfahrensingenieure”, Hannover, September 21 to 23, 1988. (1989)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 12 (1989), S. 324-332 
    Details
    ISSN: 0930-7516
    Schlagwort(e): Chemistry ; Industrial Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The knowledge of the heat transfer coefficient on the inner side of a heated vessel wall is of the utmost importance for the design of agitated vessels. In the case of large Reynolds numbers, the heat transfer is mainly determined by these numbers whereas, with small Reynolds numbers, the heat transfer is better described by considering the Grashof number. Investigations of heat transfer in agitated narrow vessels have shown that the height/diameter ratio exerts virtually no influence on the heat transfer when multi-impeller stirrers are used. The heat transfer to stirred suspensions can be described by relationships valid for liquids if the characteristic data of the liquid are replaced by those of the suspension and when the solids volume concentration is also taken into account. This relationship allows the heat transfer coefficient to be calculated for given solids volume concentrations of up to 60%.
    Zusätzliches Material: 22 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/ceat.270120145
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  • 57
    Digitale Medien
    Digitale Medien
    Design and analysis of a state observer for the temperature front of a retification columnExtended version of a paper presented by G. Feig at the “Jahrestreffen der Verfahrens-Ingenieure”, Hannover, September 21 to 23, 1988. (1989)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 12 (1989), S. 339-344 
    Details
    ISSN: 0930-7516
    Schlagwort(e): Chemistry ; Industrial Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: In order to achieve optimal energy-saving, load-dependent operation of rectification columns, development and implementation of model-based control concepts are necessary. This paper reports on the design and step-by-step testing of a state observer for the estimation of two state variables which cannot be measured directly, namely the vapour rate and the location of mass transfer zone (temperature front) in the stripping section of a production column. The procedure is described, and the relevant simulation and operation results are presented and discussed. Initial experience, gained when the concept was put into practical operation, is reported.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/ceat.270120147
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  • 58
    Digitale Medien
    Digitale Medien
    Directional specific shear-rate measurements in gas-liquid two-phase flow (1989)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 12 (1989), S. 374-378 
    Details
    ISSN: 0930-7516
    Schlagwort(e): Chemistry ; Industrial Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Wall shear rate vectors in a bubble column and an airlift-loop reactor were measured using the limiting-current electrodiffusion technique. In connection with a new circular three-segment probe, the magnitudes and directions of shear rates were determined. The results for the bubble column are in good agreement with hot film-anemometry measurements in the same column. Moreover, the spiral flow structure, postulated in the shear-zone model of Franz, has been confirmed. In addition, the measuring technique was used to determine the flow structure in an airlift-loop reactor employed for the cultivation of animal cells. The region above the gas distributor of this fermenter has been identified as critical for mechanical damage to the cells.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/ceat.270120153
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  • 59
    Digitale Medien
    Digitale Medien
    Effect of transfer on droplet size in liquid-liquid dispersions (1989)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 12 (1989), S. 395-399 
    Details
    ISSN: 0930-7516
    Schlagwort(e): Chemistry ; Industrial Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Mean droplet diameter of the dispersed phase in pulsed plate extraction columns was measured for binary and ternary systems. A change in the droplet size in the presence of solute, dependent on such factors as the direction of mass transfer, droplet size in the binary system, radio of diffusion coefficients, viscosity of the continuous phase, interfacial tension and driving force for extraction was observed. Two new empirical correlations of mean droplet sizes in mass transfer conditions are proposed. These correlations have been successfully applied to other extraction columns.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/ceat.270120156
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  • 60
    Digitale Medien
    Digitale Medien
    Flow phenomena and local heat and mass transfer in corrugated passagesPaper presented by G. Gaiser at the “Jahrestreffen der Verfahrens-Ingenieure”, Hannover, September 21 to 23, 1988. (1989)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 12 (1989), S. 400-405 
    Details
    ISSN: 0930-7516
    Schlagwort(e): Chemistry ; Industrial Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Flow phenomena, local heat and mass transfer and pressure drop of corrugated passages in process equipment are examined. Based on a method for measuring local heat and mass transfer, developed in previous investigations, a procedure has been formulated for the determination of local heat and mass transfer in corrugated passages. Using the analogy between heat and mass transfer, this technique allows the determination of heat transfer distributions in any structures with high local resolution. The corresponding pressure drop is presented together with the local and integral heat and mass transfer of different structures. It is shown that differences in heat and mass transfer as well as in pressure drop are due to different flow phenomena which also characterize mixing behaviour.
    Zusätzliches Material: 16 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/ceat.270120157
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  • 61
    Digitale Medien
    Digitale Medien
    A study of gas and liquid distributions in structured packingsPaper presented by R. Stikkelman at the “Jahrestreffen der Verfahrens-Ingenieure”, Hannover, September 21 to 23, 1988. (1989)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 12 (1989), S. 445-449 
    Details
    ISSN: 0930-7516
    Schlagwort(e): Chemistry ; Industrial Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: This study describes the gas and liquid distributions in a column with structured packings. The column is 0.5 m in diameter. It is equipped with a total of 1289 detectors in the top and bottom cross-sections. These detectors provide a detailed picture of the gas and liquid flows through elements of only 25 × 25 mm2. The maldistribution in the gas bulk flow is negligible. Only the observed wall can contribute to malperformance. The gas flows in parallel to sheet orientation, thus introducing a radial transport. Together with the change in the orientation of subsequent packing elements, this results in good gas mixing. It was observed that the liquid wall flow rate decreases when the gas velocity exceeds 1.7 m/s. Up to the loading point, the maldistribution of the liquid is constant. Above this point, the equality of the distribution deteriorates rapidly, due to the occurrence of large-scale liquid segregation.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/ceat.270120164
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  • 62
    Digitale Medien
    Digitale Medien
    Investigation of a wet dust scrubber with a pneumatic nozzle: Dust collection based on turbulent diffusionPaper presented by P. Centner at the “Jahrestreffen der Verfahrens-Ingenieure”, Hannover, September 21 to 23, 1988. (1989)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 12 (1989), S. 439-444 
    Details
    ISSN: 0930-7516
    Schlagwort(e): Chemistry ; Industrial Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The “nozzle scrubber” is a wet scrubber in which the scrubbing water is dispersed in dust laden gas stream by means of one or more pneumatic nozzle. This scrubber is distinguished by an excellent collection efficiency for submicron dust at an unusually low energy and water consumption. So far, the physical effects affecting the separation cannot be explained by a well-defined theory. Therefore, it is sensible to investigate the collection efficiency with regard to the mechanisms of inertial impaction, turbulent diffusion and coalescence induced by turbulence. The experimental equipment is of a very simple design. A light scattering device was used to measure the particle distributions. In addition, electron micrographs were analyzed to obtain information about the submicron particles. The influence of operating parameters on grade efficiency has been demonstrated by their systematic variation. The contribution of turbulent diffusion to the collection efficiency has been confirmed; nevertheless, grade efficiencies were also measured when inertial impaction prevailed.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/ceat.270120163
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  • 63
    Digitale Medien
    Digitale Medien
    On-line measurement of partical size distribution and partical concentration in suspensions by ultrasonic spectrometryPaper presented by U. Riebel at the “Jahrestreffen der Verfahrens-Ingenieure”, Hannover, September 21 to 23, 1988. (1989)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 12 (1989), S. 433-438 
    Details
    ISSN: 0930-7516
    Schlagwort(e): Chemistry ; Industrial Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The principle of ultrasonic spectrometry is based on the measurement of the ultrasonic extinction caused by the presence of particles. From measurements at different frequencies and with the knowledge of the ultrasonic extinction cross section of the particles, a system of linear equations can be established and solved to obtain the particle size distribution and particle concentration. With an experimental apparatus covering the frequency range from 1.7 MHz to 81 MHz, particles ranging from 20 to 1000 μm in diameter may be analyzed. The measurements can be carried out with particle concentrations as high as 10% by volume.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/ceat.270120162
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  • 64
    Digitale Medien
    Digitale Medien
    Masthead (1989)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 12 (1989) 
    Details
    ISSN: 0930-7516
    Schlagwort(e): Chemistry ; Industrial Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/ceat.270120101
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  • 65
    Digitale Medien
    Digitale Medien
    Separation of liquid from vapour upon pressure relief (1989)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 12 (1989), S. 54-63 
    Details
    ISSN: 0930-7516
    Schlagwort(e): Chemistry ; Industrial Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: When a chemical reactor is depressurized or pressure in a vessel, filled with saturated liquid, has to be decreased, generally both vapour and liquid flow out through the relief valve. Since chemical reactors are usually operated with toxic and explosive fluids, the discharged liquid which vaporizes on the ground around the vessel may reach dangerous concentrations, causing explosions or accidents with the poisonous gas. During a research project, some fundamentals were developed for the design of separation systems which separate liquid from vapour and store it in a receiver. The requirement for a separation efficiency of a least 80% is related to the condition that the separated liquid should flow back into the reactor still during the pressure relief phase. For safety reasons, both separation and re-storage are to be carried out without the supply of external energy. Theoretical and experimental investigations of pressure distribution within the piping to the relief valve and in an integrated separator show that re-storage of the separated liquid in the vessel can be achieved under certain flow conditions. Therefore, the separator must be integrated in the pipe at a certain height above the vessel, so that the hydrostatic pressure of the separated liquid, corresponding to the difference in height, is sufficient to lead it back through another pipe against the internal pressure of the vessel. First, several separators were tested with air-water mixtures. A swirl separator and a reversing separator have been developed to such an extent that they appear suitable for the set task. Experimental results with air-water mixtures and refrigerant R12 upon pressure relief show separation efficiencies of between 90 and 100% at low pressure drops within the whole operating range. As an alternative to separation outside the vessel, a rotary separator was also developed which is fixed to the outlet opening in the vessel. A centrifugal field is produced by the separator rotor and the heavier liquid is largely separated from the vapour so that only drops in the range 〈 100 μm flow together with the vapour towards the central standpipe. The outflowing vapour leaves the separator via 4 tangentially arranged nozzles, under critical conditions. The vapour flow momentum drives the separator rotor. The arrangement was developed and tested during various series of experiments, under conditions or pressure relief with refrigerant R12. So far, separation efficiencies between 60 and 95% have been achieved at stirring speeds of up to 2500 min-1.
    Zusätzliches Material: 17 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/ceat.270120110
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  • 66
    Digitale Medien
    Digitale Medien
    Absorption process for the removal of organic solvents from exhaust air (1989)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 12 (1989), S. 63-70 
    Details
    ISSN: 0930-7516
    Schlagwort(e): Chemistry ; Industrial Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: It is shown in this report that, under certain conditions, cleaning of exhaust air by absorption presents an interesting alternative to the existing methods. In particular, this process can be used with advantage for small quantities of exhaust air, high and strongly fluctuating solvent concentrations and solvent mixtures such as those occurring in batch operation. A washing agent was employed which had not been previously used for this purpose. Its properties, which were investigated in the laboratory, were confirmed during a 15-months' trial period in a semi-industrial plant. The process and plant were optimized for practical use. Through its option of solvent recovery from exhaust air, this physical absorption process contributes to environmental control.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/ceat.270120111
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  • 67
    Digitale Medien
    Digitale Medien
    Advances in modelling and design of multitubular fixed- bed reactorsI. Description of Interaction Between Reactants and Coolant (1989)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 12 (1989), S. 113-130 
    Details
    ISSN: 0930-7516
    Schlagwort(e): Chemistry ; Industrial Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Starting from the review of current industrial designs, the present paper analyzes thermal interaction between reactants and coolant in multitubular fixed-bed reactors. The interaction can be described quantitatively in terms of parameters characterizing transport processes both on the tube side and in the intertubular space. The study provides a detailed discussion of existing methods and correlations used for the evaluation of these parameters. The methods presented here can be considered as a basis for the development of a more comprehensive approach to the modeling and design of multitubular catalytic reactors.
    Zusätzliches Material: 13 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/ceat.270120117
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  • 68
    Digitale Medien
    Digitale Medien
    Determination of size and stress intensity factors for leaks in nozzle attachmentsPaper presented by G. Wiedemann at the “Jahrestreffen der Verfahrens-Ingenieure”, Freiburg, September 30 to October 2, 1987. (1989)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 12 (1989), S. 131-137 
    Details
    ISSN: 0930-7516
    Schlagwort(e): Chemistry ; Industrial Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The prediction of leak areas in pressure vessels is an important objective in the safety analysis of chemical plants. Using suitable design rules, a leak-before-break behaviour can be achieved. This contribution outlines a procedure for the leak-before-break design of nozzle attachments and the determination of the size of the corresponding opening area. In addition, K1-factors and leak areas for a number of nozzle geometries have been calculated and plotted.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/ceat.270120118
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  • 69
    Digitale Medien
    Digitale Medien
    Combined process treatment of molasses fermentation waste water for biogas generation (1989)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 12 (1989), S. 109-112 
    Details
    ISSN: 0930-7516
    Schlagwort(e): Chemistry ; Industrial Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Anaerobic fermentation of molasses distillery slops to biogas was carried out with the aid of an adapted and selected anaerobic mixed culture. Two different types of fermenters were used, namely an agitated pretreatment fermenter and a column fermenter with glass rings as carriers for micro-organisms. The production of biogas in both fermenters amounted to between 0.6 and 0.8 dm3/g COD. The aerobic pretreatment of distillery slops by T. fermentans, yeast during a 4 to 6 h period allows a high reduction of COD in the subsequent anaerobic phase of the process. After treatment of the distillery slops by T. fermentans, it was possible to convert between 85 and 93% of the organic matter to methane. Conversion was about 93% with loading rate of 25g COD/litre day.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/ceat.270120116
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  • 70
    Digitale Medien
    Digitale Medien
    A new particle size effect (1989)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 12 (1989), S. 147-154 
    Details
    ISSN: 0930-7516
    Schlagwort(e): Chemistry ; Industrial Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The sintering effect of highly dispersed metals is the reason for the following phenomena: thermal deactivation, particle size effect, separable or non-separable kinetics and the isokinetic relationship ( = compensation effect). A comparison of these phenomena reveals a contradiction which can be reconciled by a new particle size effect. This effect is characterized in the following way: The dependence of specific activity on particle size is always connected with a variation of the activation energy, caused by the particle size distribution. Therefore, this effect is referred to as the partical size and distribution effect, P.S.D.E. This new concept describes all the observed phenomena of the conventional partical size effect. Moreover, it is consistent with similar effects such as non-separable kinetics and the isokinetic relationship. In consequence, the method of isothermal measurement of specific activity is inadequate.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/ceat.270120120
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  • 71
    Digitale Medien
    Digitale Medien
    Conversion of methanol to light olefins over zeolite H-T (1989)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 12 (1989), S. 155-161 
    Details
    ISSN: 0930-7516
    Schlagwort(e): Chemistry ; Industrial Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The conversion of methanol over zeolite H-T was investigated in a fixed bed reactor. H-T was prepared from Na-T by ion exchange with HCl and NH4Cl solutions. The HCl solution caused appreciable dealumination. High yields of ethene were obtained with NH4Cl exchangeed zeolites Na-T with 45% decationization, high proprne yields with low HCl or NH4Cl Exchanged catalysts. Low methanol partial pressures and short residence times favoured the formation of lower olefins. Lowest coking rates were observed at a reaction temperature of 693 K. The catalytic activity decrased slowly with the number of reaction/regeneration cycles. The distribution of procucts 〉 C2 could be described by the most probable distribution of Schulz and Flory.
    Zusätzliches Material: 13 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/ceat.270120121
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  • 72
    Digitale Medien
    Digitale Medien
    Generalization of AIChE and colburn models for tray efficiency (1989)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 12 (1989), S. 333-339 
    Details
    ISSN: 0930-7516
    Schlagwort(e): Chemistry ; Industrial Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The most important investigations on liquid weeping and entrainment in plate columns with downcomers are reveiwed. The formulae for calculating column plate efficiency under conditions of liquid weeping and entrainment have been derived on the basis of mass balance equations. The presented model is a generalization of the models of AIChE and Colburn. Sample results are shown graphically. The effect of liquid entrainment on tray efficiency predicted by the model is in agreement with experimental data of FRI.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/ceat.270120146
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  • 73
    Digitale Medien
    Digitale Medien
    Selective absorption of ethylene by methanol solutions of Copper(I) chloride-ethylenediamine complex (1989)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 12 (1989), S. 356-357 
    Details
    ISSN: 0930-7516
    Schlagwort(e): Chemistry ; Industrial Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/ceat.270120150
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  • 74
    Digitale Medien
    Digitale Medien
    Continuous crystallization of potassium carbonate (1989)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 12 (1989), S. 345-350 
    Details
    ISSN: 0930-7516
    Schlagwort(e): Chemistry ; Industrial Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Continuous crystallization of potassium carbonate was investigated in a mixed suspension mixed product removal (MSMPR) crystallizer with 7.0 1 working volume. Highly polydispersed product was obtained, with x50 varying between 320 and 670 μm. Crystal growth rates can be described by the model of Abegg, Stevens and Larson (ASL) (size dependent crystal growth rate). Values of G0 = 8.6 × 10-9 to 3.6 × 10-8 m/s and B0/ϕ = 2.7 × 108 to 4.2 × 109 1/m3s were obtained for mT = 45 to 92 kg/m3 and ε = 0.45 ± 0.05 W/kg. Nucleation kinetics at 27 °C can be described by the equation: B0/ϕ = kBϕsε0.73G02.5. Since G0 ∝ σ, convection and/or diffusion rather than surface integration are the crystal growth controlling mechanisms.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/ceat.270120148
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  • 75
    Digitale Medien
    Digitale Medien
    Experienmental and theoretical combustion rates of graphite plates in hot parallel flows of air and O2/N2 mixturesPaper presented by H. Wilhelmi at the “Jahrestreffen der Verfahrens-Ingenieure”, Hannover, September 21 to 23, 1988. (1989)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 12 (1989), S. 351-356 
    Details
    ISSN: 0930-7516
    Schlagwort(e): Chemistry ; Industrial Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Combustion rate of flat graphite plates in oxidizing flows with velocities of up to 80 m/s and stagnation temperatures between 1600 and 2500 K were investigated. The flow field and its local properties were recorded in addition to surface temperature of the solid sample and change in surface structure. The experiments, in which the surface temperature of graphite was adjusted and carefully controlled by radiation shields, indicated that, under these experimental conditions, between 15 and 20 wt-% of carbon was lost as particles of up to 100 μm which burnt rapidly in the boundary layer region. Subtraction of erosion rates from the recorded global combustion rates yield the heterogeneous chemical reaction rates, which are approximated by an Arrhenius type function for the mathematical modelling. Since steep temperature and concentration gradients occur in the boundary layer, the local values of the multicomponent transport coefficients were evaluated in order to design a more realistic computational procedure which, in addition, also includes radiative heat transfer. Computational checks revealed that, in the past, the assumption of mean constant values for the transport coefficients has led to errors of up to 100% in the evaluation of the chemical reaction and global combustion rates.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/ceat.270120149
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  • 76
    Digitale Medien
    Digitale Medien
    Simulation of primary and secondary reformers for improved energy performance of an ammonia plant (1989)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 12 (1989), S. 358-364 
    Details
    ISSN: 0930-7516
    Schlagwort(e): Chemistry ; Industrial Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The energy consumption of ammonia plants based on steam reforming of naphtha or natural gas can be reduced by shifting the reforming load from the primary to the secondary reformer. It is shown that lowering of the primary reformer operating temperature 20 °C results in 2% increase of unconverted methane content in the outlet stream. The increased methane content can be processed in the secondary reformer if the process air inlet temperature is increased to 400 °C. The lower operating temperature reduces the energy consumption of the primary reformer by about 6% (and the overall consumption by about 2%) and also prolongs the service life of reformer tubes.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/ceat.270120151
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  • 77
    Digitale Medien
    Digitale Medien
    Overproduction of lipase with staphylococcus carnosus (pLipPS1) under modified gravity in a centrifugal field bioreactorReport from SFB 145 “Biological, chemical and technical fundamentals of bioconversion” (1989)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 12 (1989), S. 364-373 
    Details
    ISSN: 0930-7516
    Schlagwort(e): Chemistry ; Industrial Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Fermentation under modified gravity could be of interest in application to (a) increasing productivity of growth and growth linked production with microorganisms at high cell densities and (b) increasing the productivity of highly viscous pseudoplastic polysaccharide fermentation. In both cases, higher oxygen transfer rates in centrifugal fields result in higher productivities since these fermentations are usually oxygen limited. A further aspect of fermentation under increased gravity is the reduction of foam since foam coalescence time decreases with acceleration number. On the other hand, under microgravity, shear reduction would allow growth and production even for very shear sensitive organisms. In order to carry out fermentations under modified gravity, a special type of fermenter-the centrifugal field bioreactor CFBR-has been developed at the Institute of Chemical Engineering (Head: Prof. Mersmann) of the Technical University of Munich. For the first time, exoprotein biosynthesis of lipase with S. carnosus has been carried out under sterile and controlled conditions in this novel bioreactor, in presence of increased mass forces.
    Zusätzliches Material: 17 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/ceat.270120152
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  • 78
    Digitale Medien
    Digitale Medien
    Measurement of heat transfer coefficients in tubes by temperature oscillation analysisPaper presented at the “Jahrestreffen der Verfahrens-Ingenieure”, Hannover, September 21 to 23, 1988. (1989)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 12 (1989), S. 379-387 
    Details
    ISSN: 0930-7516
    Schlagwort(e): Chemistry ; Industrial Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: An experimental technique and evaluation method is described for the determination of local heat transfer coefficients in tubes or other ducts. By means of a rotary mixing valve, cold and warm fluid flows are mixed in order to generate an arbitrarily shaped but periodically oscillating inlet temperature profile at the test tube. The propagation of the fundamental harmonic oscillation from the fluid to the outer surface of the tube wall is calculated analytically. Comparison of fluid and wall oscillations yields the heat transfer coefficient to be measured. The inaccurate measurement of fluid bulk temperature in the centre of the cross-section is compensated by an additional correction. Experiments were carried out with turbulent water flow through a copper tube. Measured heat transfer coefficients were compared to values calculated using Hausen's equation and good agreement was obtained.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/ceat.270120154
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  • 79
    Digitale Medien
    Digitale Medien
    Studies in liquid-liquid direct-contact heat transferPaper presented by E. Marschall at the “Jahrestreffen der Verfahrens-Ingenieure”, Hannover, September 21 to 23, 1988. (1989)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 12 (1989), S. 388-394 
    Details
    ISSN: 0930-7516
    Schlagwort(e): Chemistry ; Industrial Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Liquid-liquid direct-contact heat transfer in a spray column was studied numerically for a low hold-up. The solutions of the conservation equations of mass, momentum and energy for both phases agree well with earlier experimental results, if one assumes a rigid liquid-liquid interface. Heat transfer inside is dominated by transient conduction and natural convection. It was found that the Nusselt number for free convection depends essentially only on the Rayleigh number.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/ceat.270120155
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  • 80
    Digitale Medien
    Digitale Medien
    Evaporation rate and separation factor of molecular distillation in a falling film apparatus (1989)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 12 (1989), S. 406-413 
    Details
    ISSN: 0930-7516
    Schlagwort(e): Chemistry ; Industrial Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: During molecular distillation in a falling film apparatus, temperature and concentration of the more volatile components undergo a marked decrease in axial and radial directions, due to the distillation in vacuo. The gradients produce changes in the rate of surface evaporation and separation efficiency along the flow path. A theoretical study of this problem is presented for binary mixtures. The respective differential equations for heat and mass transfer in the liquid film are solved numerically. As the results demonstrate, the aspect ratio of an apparatus should be large when a high separation is required and small when a high distillation rate is more important.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/ceat.270120158
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  • 81
    Digitale Medien
    Digitale Medien
    The importance of dynamic performance and testing of industrial thermometers in process control (1989)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 12 (1989), S. 419-426 
    Details
    ISSN: 0930-7516
    Schlagwort(e): Chemistry ; Industrial Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: This paper considers the dynamic performance of instruments in control systems. Errors connected with transient measurements are discussed. It is shown that it is not always proper to assign common statistical properties to these dynamic errors. Emphasis is placed on temperature sensors. Common industrial thermometers are described and factors affecting their response discussed. An a-priori dynamic performance prediction procedure is presented. This permits preinstallation estimation of response characteristics of sensors used in industrial processes. Sensors in service also require performance assessment since they can deteriorate with use. In-situ testing is useful for this purpose and a recently develolped procedure is described.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/ceat.270120160
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  • 82
    Digitale Medien
    Digitale Medien
    Parameters influencing the mean particle size of a crystalline productPaper presented by A.B. Mersmann at the “Jahrestreffen der Verfahrens-Ingenieure”, Hannover, September 21 to 23, 1988.Dedicated to Professor Dr.-Ing. Dr. h.c. Ernst-Ulrich Schlünder on the occasion of his 60th birthday (1989)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 12 (1989), S. 414-419 
    Details
    ISSN: 0930-7516
    Schlagwort(e): Chemistry ; Industrial Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Crystallizer design has to take into account the physical and chemical properties of the solution and solids as well as the geometry, type and operating conditions of the crystallizer. The most important property of a crystallizing system is its solubility. High solubility leads to low relative supersaturation and large mean crystal size, and vice versa. High solubility systems can be sensitive to abrasion and attrition. For low solubility systems, mixing is crucial.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/ceat.270120159
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  • 83
    Digitale Medien
    Digitale Medien
    Modelling and simulation of monopropellant hydrazine thrusters for spacecraft position controlDedicated to Professor Dr. Dr. h.c. Ewald Wicke on the occasion of his 75th birthday (1989)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 12 (1989), S. 426-432 
    Details
    ISSN: 0930-7516
    Schlagwort(e): Chemistry ; Industrial Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Modelling of the kinetics of a 20-N hydrazine thruster is carried out by considering two different heterogeneous reaction channels for hydrazine decomposition to the intermediate ammonia. The parameters of the reactor model are estimated by making use of temperature profiles at the wall of the decomposition chamber. Simulated ageing of the catalyst revealed an increase of the rate of deactivation with increasing total firing time.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/ceat.270120161
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  • 84
    Digitale Medien
    Digitale Medien
    Phenotypic effects of overexpression of PKCβ1 in rat liver epithelial cells (1989)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 41 (1989), S. 179-188 
    Details
    ISSN: 0730-2312
    Schlagwort(e): protein kinase C ; TPA ; cell transformation ; gene expression ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Chemie und Pharmazie , Medizin
    Notizen: We have used a previously described retroviral expression vector pMV7-PKCβ1 to develop derivatives of two rat liver epithelial cell lines, K16 and K22, that stably express about tenfold-higher PKC activity than control cells. Despite these high levels of PKC, these cells did not exhibit gross morphologic changes, anchorage-independent growth, or tumorigenicity. K16PKC-4 and K22PKC-2, two lines with the highest PKC enzyme activity, were studied further in terms of several responses to the phorbol ester tumor promoter TPA. When treated with 100 ng/ml of TPA, the control K16MV7 and K22MV7 cells displayed a slight change in morphology, whereas the K16PKC-4 and K22PKC-2 cells displayed a marked change in morphology. Northern blot analyses demonstrated that TPA induced increased levels of fos, myc, phorbin, and ODC RNAs in control K16MV7 and K22MV7 cells, with maximum induction occurring at about 0.5, 1, 8, and 8 h, respectively. In K16PKC-4 and K22PKC-2 cells, TPA induction of phorbin and ODC RNAs was markedly enhanced, but this was not the case for myc and fos RNAs. In addition, the levels of myc RNA were constitutively higher in both K16PKC-4 and K22PKC-2 cells than in the control cells. Taken together, these results provide direct evidence that PKC plays a critical role in modulating the expression of myc, phorbin, and ODC RNAs. On the other hand, overexpression of PKCβ1 is not itself sufficient to cause cell transformation.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jcb.240410403
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  • 85
    Digitale Medien
    Digitale Medien
    Heart anatomy and developmental biology (1988)
    Springer
    Cellular and molecular life sciences 44 (1988), S. 910-919 
    Details
    ISSN: 1420-9071
    Schlagwort(e): Heart embryology ; developmental biology ; differentiation ; morphogenesis ; gene expression
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The subject of heart development has attracted the interest of many embryologists over the last two centuries. As a result, the main morphologic features of the developmental anatomy of the heart are already well established. Although there are still some controversial points, and there is probably much descriptive work yet to be done, emphasis is currently being placed on developmental mechanisms rather than simply on descriptive facts. The availability of new techniques and the overall advances in biological research are placing heart embryology in a new perspective. Today, we do not simply ask whether one or another embryonic structure arises further right or further left; instead, we are studying how cells, tissues, and their microenvironment interrelate at the several levels of biological organization (from the gene upwards) so as to give rise to a mature organ with a distinct shape and well-established functions. This paper attempts to review some of the basic aspects of the developmental anatomy of the heart. Descriptive embryology is used here as a tool. Emphasis is placed on developmental mechanisms, and on the present knowledge of how these mechanisms are related to the structural development of the heart.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01939884
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  • 86
    Digitale Medien
    Digitale Medien
    A molecular view of cardiogenesis (1988)
    Springer
    Cellular and molecular life sciences 44 (1988), S. 930-936 
    Details
    ISSN: 1420-9071
    Schlagwort(e): Cardiac development ; embryogenesis ; gene expression ; complementary DNA ; molecular methodologies ; myocardial contractility ; myosin ; atrial natriuretic factor
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Cardiac development involves a complex integration of subcellular processes into multicellular and, finally, whole organ effects. Until recently it has been difficult to investigate the genetic control of this organ level differentiation of the heart. The proliferation of molecular biology methodologies has provided mechanisms to directly investigate the control of these processes. This article focuses on molecular lines of research on two key areas in cardiac development: the regulation of expression of sarcomeric contractile and regulatory proteins, and atrial natriuretic factor. Molecular approaches are described which have allowed investigators to begin to determine the tissue and stage-specific expression of genes, to locate those genes in the genome, determine their sequences, and to directly investigate the mechanisms controlling their expression.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01939886
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  • 87
    Digitale Medien
    Digitale Medien
    Aberrant protamine 1/protamine 2 ratios in sperm of infertile human males (1988)
    Springer
    Cellular and molecular life sciences 44 (1988), S. 52-55 
    Details
    ISSN: 1420-9071
    Schlagwort(e): Human sperm ; human protamine ; protamine 1 ; protamine 2 ; protamine 3 ; infertility ; gene expression
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Protamines were extracted from the sperm of fertile and infertile human males and the relative proportion of protamines 1, 2, and 3 were determined by scanning microdensitometry following electrophoresis of total protamine in polyacrylamide gels. The proportion of the three protamines was found to be similar in sperm obtained from different normal males. The distribution of protamines in sperm obtained from a select group of infertile males producing an elevated level of large sperm heads, in contrast, was different from that of the fertile males.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01960243
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  • 88
    Digitale Medien
    Digitale Medien
    Post-castration rebound of an androgen regulated prostatic gene (1988)
    Springer
    Molecular and cellular biochemistry 84 (1988), S. 3-15 
    Details
    ISSN: 1573-4919
    Schlagwort(e): prostate ; androgens ; gene expression ; in situ hybridization
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie , Medizin
    Notizen: Summary After castration, the rat dorsolateral prostate M-40 mRNA initially decreased then rebounded to precastrated levels. The cellular site of M-40 expression and its renewed expression after castration was defined by in situ hybridization histochemistry. In situ hybridization with either a 32P-labeled or biotin-labeled M-40 cDNA probe demonstrated that M-40 mRNA levels were higher in the lateral than dorsal prostate. A second androgen regulated gene, RWB, also was highly expressed in the lateral prostate. The biotinylated cDNA probes provided microscopic resolution of the expressing cells, revealing two distinct morphologies of lateral epithelium which expressed both the M-40 and RWB mRNA. These morphologies appeared in ducts which contained either epithelial cell sheets that were highly convoluted or thinner epithelial cells with a minimal degree of convolution. The RWB mRNA decreased in both cell populations in response to androgen withdrawal. The decline and reappearance of M-40 mRNA also appeared in both epithelial cell types. These data demonstrated that after castration the M-40 mRNA initially decreased as expected for an androgen sensitive gene and then progressed to a fully inducible state. The mechanism of this progression remains to be elucidated.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00235188
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  • 89
    Digitale Medien
    Digitale Medien
    The cat hemoglobin polymorphism: Southern blot analysis of theβ-globin gene region from cats of various Hb A/Hb B phenotypes (1988)
    Springer
    Biochemical genetics 26 (1988), S. 239-248 
    Details
    ISSN: 1573-4927
    Schlagwort(e): cat hemoglobins ; polymorphism ; DNA ; restriction endonuclease ; gene expression
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract The molecular basis for the genetic control of variable proportions of the two cat hemoglobins Hb A(α2β 2 A ) and Hb B (α2β 2 B ) was investigated. Ratios of Hb A/Hb B vary between 50/50 and 90/10 among members of the mongrel cat population, with clusters around 50, 35, and 10% Hb B. Genomic DNA from cats of 50/50, 70/30, and 90/10 phenotypes were cut by restriction endonucleasesHindIII,EcoRI,BamHI,Bg1II,and Pst1 and hybridized to a fragment of the human β-globin gene. The results of the Southern blots suggested a pattern of homozygote, heterozygote, homozygote for the respective cat phenotypes, 50/50, 70/30, and 90/10. Therefore, the cat hemoglobin polymorphism seems to result from the possible combinations of an allelic gene pair.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00561463
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  • 90
    Digitale Medien
    Digitale Medien
    Molecular cloning of two isoinhibitor forms of chymotrypsin inhibitor 1 (CI-1) from barley endosperm and their expression in normal and mutant barleys (1988)
    Springer
    Plant molecular biology 10 (1988), S. 521-535 
    Details
    ISSN: 1573-5028
    Schlagwort(e): barley ; chymotrypsin inhibitor ; gene expression ; endosperm
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Full-length cDNA clones for barley chymotrypsin inhibitor 1 (CI-1) have been isolated from an endosperm-specific cDNA library. Hybridization and nucleotide sequence analyses indicate that these cDNAs represent two distinct types of CI-1 mRNA which we have called CI-1A and CI-1B. Both mRNAs encode polypeptides of 83 residues (M r=8790 and 8960) which differ at eleven positions. The full-length cDNA sequences do not predict N-terminal signal peptide extensions indicating that CI-1 is synthesized in the mature form in contrast to the homologous proteinase inhibitors of tomato and potato. Northern hybridization experiments show that the CI-1 genes are under strict developmental and organ-specific control. CI-1 transcripts were first detected in the developing barley endosperm between 12 and 14 days after anthesis but no CI-1-related sequences were detected in the RNA preparations from shoots, leaves or roots. The expression of CI-1 was also studied in the high-lysine barley mutants Hiproly, Risø 56 and Risø 1508. Approximately 15-fold (Hiproly) and 4-fold (Risø 56 and 1508) higher levels of CI-1 mRNA were detected in the mutant endosperms compared to normal barley. These results correlate well with the increased deposition of CI-1 in the high-lysine lines and show that the differential expression is controlled mainly at the level of transcription or stability of the mRNA. Using Southern-blots of barley DNA we estimate that there are three copies of CI-1 per haploid genome in both normal and mutant barley lines.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00033607
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  • 91
    Digitale Medien
    Digitale Medien
    Isolation of an alfalfa histone H3 gene: structure and expression (1988)
    Springer
    Plant molecular biology 11 (1988), S. 641-649 
    Details
    ISSN: 1573-5028
    Schlagwort(e): codon usage ; gene expression ; histone H3 gene ; Medicago sativa ; somatic embryos
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract A histone H3 gene was isolated from a dicotyledonous plant, alfalfa (Medicago sativa). The sequence analysis of this gene revealed no obvious GC preference in its codon usage. Apart from containing most of the typical consensus sequences found in both animal and plant histone genes, the alfalfa H3 gene exhibits distinct structural features such as (1) the unusual location of two GATCC motifs in its 5′ flanking sequence, (2) the existence of a CGCGGATC on the nonsense strand at position −232, (3) the existence of a long palindromic structure, and (4) several polyadenylation signal-like sequences in the 3′ flanking region. There are about 160 copies of histone H3 gene in alfalfa tetraploid genome. Using the alfalfa H3 gene as a probe to study the pattern of histone H3 transcripts in the alfalfa, we found that the H3 RNAs are undetectable in leaves, more in stems than in roots, and highest in somatic embryos. Moreover, the RNA products of H3 genes in all alfalfa tissues tested show unusually long nontranslated region compared to those of animal histone genes. An additional high molecular weight species of H3 transcript was detected only in somatic embryos.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00017464
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  • 92
    Digitale Medien
    Digitale Medien
    Tissue-specific expression of a pea legumin gene in seeds of Nicotiana plumbaginifolia (1988)
    Springer
    Plant molecular biology 10 (1988), S. 203-214 
    Details
    ISSN: 1573-5028
    Schlagwort(e): Agrobacterium ; gene expression ; legumin (Pisum) ; Nicotiana ; seed storage protein ; transformation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract A 3.4-kilobase genomic DNA fragment from Pisum sativum L. containing the LegA gene, which encodes a major legumin storage protein, was transferred to Nicotiana plumbaginifolia using an Agrobacterium tumefaciens strain containing the Bin 19 binary vector system. Northern hybridisation analysis of legA-transformed plants demonstrated that legumin-specific RNA was present in developing seeds but not in developing leaves. Legumin protein was immunologically detected in the mature seeds of legA-transformed plants, and was present as the correct-size protein composed of disulphide-bonded polypeptides. It is concluded that the transferred pea genomic fragment contains all the information necessary for seed-specific expression of the legA gene, and for correct processing of the primary transcript and the precursor legumin protein.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00027397
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  • 93
    Digitale Medien
    Digitale Medien
    Molecular cloning and analysis of four potato tuber mRNAs (1988)
    Springer
    Plant molecular biology 11 (1988), S. 255-269 
    Details
    ISSN: 1573-5028
    Schlagwort(e): potato ; patatin ; proteinase inhibitor ; cloning ; gene expression
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Tuberization in potato is a complex developmental process involving the expression of a specific set of genes leading to the synthesis of tuber proteins. We here report the cloning and analysis of mRNAs encoding tuber proteins. From a potato tuber cDNA library four different recombinants were isolated which hybridized predominantly with tuber mRNAs. Northern blot hybridization experiments showed that three of them, pPATB2, p303 and p340, can be regarded as tuber-specific while the fourth, p322, hybridizes to tuber and stem mRNA. Hybrid-selected in vitro translation and nucleotide sequence analysis indicate that pPATB2 and p303 represent patatin and the proteinase inhibitor II mRNA respectively. Recombinant p322 represents an mRNA encoding a polypeptide having homology with the soybean Bowman-Birk proteinase inhibitor while p340 represents an mRNA encoding a polypeptide showing homology with the winged bean Kunitz trypsin inhibitor. In total, these four polypeptides constitute approximately 50% of the soluble tuber protein. Using Southern blot analysis of potato DNA we estimate that these mRNAs are encoded by small multigene families.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00027383
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  • 94
    Digitale Medien
    Digitale Medien
    The chloroplast-located glutamine synthetase of Phaseolus vulgaris L.: nucleotide sequence, expression in different organs and uptake into isolated chloroplasts (1988)
    Springer
    Plant molecular biology 11 (1988), S. 191-202 
    Details
    ISSN: 1573-5028
    Schlagwort(e): cDNA sequence ; chloroplast protein import ; gene expression ; glutamine synthetase ; nitrogen metabolism ; Phaseolus vulgaris L.
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Work using a full-length cDNA clone has revealed that the plastid-located glutamine synthetase (GS) of Phaseolus vulgaris is encoded by a single nuclear gene. Nucleotide sequencing has shown that this cDNA is more closely related to a cDNA encoding the plastidic GS of Pisum sativum than to cDNAs encoding three different cytosolic GS subunits of P. vulgaris. The plastid GS subunits are initially synthesized as higher M r (47000) precursors containing an N-terminal presequence of about 50 amino acids which is structurally similar to the presequences of other nuclear-encoded chloroplast proteins. The precursor has been synthesized in vitro and is imported by isolated pea chloroplasts and processed to two polypeptides of the same size as native P. vulgaris chloroplast GS subunits (M r 42000). Experiments with fusion proteins show that the N-terminal 68 amino acids of this precursor allow the cytosolic GS subunit β also to be imported and processed by isolated chloroplasts. Polyadenylated mRNA specifically related to the plastidic GS gene is most highly abundant in chloroplast-containing organs (leaves and stems) but is also detectable in roots and nodules.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00015671
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  • 95
    Digitale Medien
    Digitale Medien
    Molecular basis for the overproduction of 5-enolpyruvylshikimate 3-phosphate synthase in a glyphosate-tolerant cell suspension culture of Corydalis sempervirens (1988)
    Springer
    Plant molecular biology 11 (1988), S. 215-220 
    Details
    ISSN: 1573-5028
    Schlagwort(e): glyphosate ; herbicide ; 5-enolpyruvylshikimic acid 3-phosphate (EPSP) synthase ; enzyme overproduction ; gene expression
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Cell cultures of Corydalis sempervirens adapted to growth in the presence of 5 mM glyphosate [N-(phosphonomethyl)glycine] display a 30- to 40-fold increase in the cellular content of 5-enolpyruvylshikimic acid 3-phosphate (EPSP) synthase, the target enzyme of the herbicide. Translatable mRNA activity as well as transcript levels for EPSP synthase were increased 8-to 12-fold in the adapted (glyphosate-tolerant) as compared to the non-adapted (glyphosate-sensitive) cultures. Northern blot analysis revealed a single 1.8 kb transcript after hybridization with an oligonucleotide probe deduced from the N-terminal amino acid sequence of the enzyme. No significant differences in the relative abundance of EPSP synthase-specific DNA sequences could be detected, however, in Southern and dot blot analyses of restricted DNA isolated from the two cultures. We conclude that the overproduction of EPSP synthase in glyphosate-tolerant C. sempervirens cells is not based on the amplification of the corresponding gene.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00015673
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  • 96
    Digitale Medien
    Digitale Medien
    Cloning and characterization of a cDNA encoding a mRNA rapidly-induced by ABA in barley aleurone layers (1988)
    Springer
    Plant molecular biology 11 (1988), S. 495-506 
    Details
    ISSN: 1573-5028
    Schlagwort(e): abscisic acid ; barley aleurone layers ; cDNA cloning ; gene expression
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Abscisic acid (ABA) inhibits the gibberellic acid induced synthesis of α-amylase in barley aleurone layers, yet ABA itself induces more than a dozen polypeptides (Lin & Ho, Plant Physiol 82: 289–297, 1986). As part of our effort to elucidate the molecular action of ABA in barley aleurone layers, we have isolated and characterized an ABA-induced cDNA clone, pHV A1. This cDNA clone hybridizes to an RNA species of approximately 1.1 kb from ABA-treated barley aleurone layers. The level of this mRNA is tripled within 40 minutes after ABA treatment, reaches a peak at 8–12 h, and is present up to 48 h. The induction of this mRNA responds to concentrations of ABA as low as 10-9 M, but higher ABA concentrations induce higher expression of this mRNA. The products of hybrid-select translation and in vitro transcription/translation with pHV A1 comigrate on SDS gel as a 27 kDa polypeptide. However, the sequence of pHV A1 indicates that it has an open reading frame encoding a 22 kDa protein. This size discrepancy is probably due to the high content of the basic amino acid, lysine. This notion has been confirmed by two-dimensional gel electrophoresis showing that this polypeptide is one of the most basic proteins in ABA-treated barley aleurone layers. The deduced amino acid sequence of pHV A1 contains nine imperfect repeats 11 amino acids long which share homology with cotton Lea 7 protein (Baker, Steele & Dure, Plant Mol Biol, in press). The identity and function of the encoded product of pHV A1 is under investigation.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00039030
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  • 97
    Digitale Medien
    Digitale Medien
    CG Dinucleotides of class II MHC genes are mutation hot-spots (1988)
    Springer
    Cytotechnology 1 (1988), S. 133-138 
    Details
    ISSN: 1573-0778
    Schlagwort(e): CG suppression ; DNA methylation ; gene expression ; MHC ; mutation hot spots
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Abstract DNA methylation of human class II genes of the Major Histocompatibility Complex (MHC) was correlated with gene expression and methyl-related CG → TG and CG → CA changes. It was found that cytosine methylation of the CG dinucleotides of MHC class II genes should be involved in generating a fraction of nucleotide polymorphism, rather than in controlling transcription.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00146813
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  • 98
    Digitale Medien
    Digitale Medien
    Nicotiana chloroplast genes for components of the photosynthetic apparatus (1988)
    Springer
    Photosynthesis research 18 (1988), S. 7-31 
    Details
    ISSN: 1573-5079
    Schlagwort(e): Nicotiana ; chloroplast genome ; photosynthesis ; NADH dehydrogenase ; protein structure ; gene expression
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract In order to understand more fully chloroplast genetic systems, we have determined the complete nucleotide sequence (155, 844 bp) of tobacco (Nicotiana tabacum var. Bright Yellow 4) chloroplast DNA. It contains two copies of an identical 25,339 bp inverted repeat, which are separated by 86, 684 bp and 18,482 bp single-copy regions. The genes for 4 different rRNAs, 30 different tRNAs, 44 different proteins and 9 other predicted protein-coding genes have been located. Fifteen different genes contain introns. Twenty-two genes for components of the photosynthetic apparatus have so far been identified. Most of the genes (except the gene for the large subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase) code for thylakoid membrane proteins. Twenty of them are located in the large single-copy region and one gene for a 9-kd polypeptide of photosystem I is located in the small single-copy region. The gene for the 32-kd protein of photosystem II as well as the gene for the large subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase have strong promoters and are transcribed monocistronically while the other genes are transcribed polycistronically. We have found that the predicted amino acid sequences of six DNA sequences resemble those of components of the respiratory-chain NADH dehydrogenase from human mitochondria. As these six sequences are highly transcribed in tobacco chloroplasts, they are probably genes for components of a chloroplast NADH dehydrogenase. These observations suggest the existence of a respiratory-chain in the chloroplast of higher plants.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00042978
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  • 99
    Digitale Medien
    Digitale Medien
    Structural gene regions of Rhodobacter sphaeroides involved in CO2 fixation (1988)
    Springer
    Photosynthesis research 19 (1988), S. 63-71 
    Details
    ISSN: 1573-5079
    Schlagwort(e): CO2 fixation ; gene expression
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract From studies conducted in both our laboratory and by Gibson, Tabita and colleagues, as well as drawing on the recent studies with Alcaligenes eutrophus, we describe two genetic regions which have been identified on the chromosome of Rhodobacter sphaeroides which code for a number of enzymes involved in CO2 fixation. One region was found to contain the genes coding for fructose 1,6-bisphosphatase (fbpA), phosphoribulokinase (prkA), a 37 kDa polypeptide (cfxA), and form I ribulose 1,5-bisphosphate carboxylase/oxygenase (rbcL, S). These genes appear to be expressed in the same transcriptional direction and are tandomly arranged. A second, apparently unlinked region of the chromosome contains a duplicate (with respect to functionality of gene products) but not identical set of these same four genes. Although the gene order in both regions is apparently identical, there is approximately 4 kb of DNA separating the 3′-end of prkB and the beginning of cfxB. The specific genetic organizations and proposed roles of these two genetic regions are discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00114569
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  • 100
    Digitale Medien
    Digitale Medien
    Protein synthesis by isolated chloroplasts (1988)
    Springer
    Photosynthesis research 19 (1988), S. 129-152 
    Details
    ISSN: 1573-5079
    Schlagwort(e): chloroplast biogenesis ; gene expression ; ribosomes ; transcription ; translation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Isolated chloroplasts show substantial rates of protein synthesis when illuminated. This ‘in organello’ protein synthesis system has been advantageously utilised to elucidate the coding capacity of chloroplast and the regulation of chloroplast genes. The system is also being used recently to transcribe and translate homologous and heterologous templates. In this mini-review, we attempt to critically ecaluate the available literature and present the current and the prospective lines of research.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00114572
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