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Digitale Medien

Comparative kinetics of short and long sperm in sperm dimorphic Drosophila species (1991)

Bressac, C. ; Joly, D. ; Devaux, J. ; [weitere]

New York, NY : Wiley-Blackwell

Cell Motility and the Cytoskeleton 19 (1991), S. 269-274

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ISSN: 0886-1544

Schlagwort(e): minor and major waves ; beat frequeney ; wave propagation velocity ; coiling diameter ; storage effect ; differential behaviour ; Life and Medical Sciences ; Cell & Developmental Biology

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Biologie , Medizin

Notizen: All species of the Drosophila obscura group exhibit within-ejaculate sperm length dimorphism. The present work is a contribution to the understanding of sperm competition through a comparative study of sperm kinetic parameters in four of these species. Videomicrographic observations at 200 frames per second of sperm from males and females, out of the storage organ, prior or after storage were made. Drosophila sperm display both major and minor waves. The former is analysed by measuring coiling diameter (μm) and the latter by recording both beat frequency (s-1) and wave propagation velocity (μm·s-1). Results show that the ‘behaviour’ of short and long spermatozoa noticeably differ: short sperm kinetics remains unaltered after storage while both major and minor waves of long spermatozoa are markedly modified. Thus, evidence is provided here of a sort of “differential activation” which is assumed to result in different survival abilities of short and long sperm within the storage organ of females.

Zusätzliches Material: 2 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/cm.970190405

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2

Digitale Medien

Letters to the editor (1991)

Wiley, D. E. ; Nabetani, H. ; Nakao, S. ; [weitere]

Hoboken, NJ : Wiley-Blackwell

AIChE Journal 37 (1991), S. 791-799

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ISSN: 0001-1541

Schlagwort(e): Chemistry ; Chemical Engineering

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung

Zusätzliches Material: 2 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/aic.690370517

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3

Digitale Medien

Crystallinity and lateral crystallite size of different UHMW PE materials (1991)

Hofmann, D. ; Schulz, E. ; Fanter, D. ; [weitere]

New York, NY [u.a.] : Wiley-Blackwell

Journal of Applied Polymer Science 42 (1991), S. 863-866

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ISSN: 0021-8995

Schlagwort(e): Chemistry ; Polymer and Materials Science

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie , Maschinenbau , Physik

Notizen: Nascent high-molecular-weight (UHMW) polyethylene (PE) samples of different origins show a rather high crystallinity of about 70-75% and contain both a major portion of orthorhombic extended chain crystallites and a minor portion of triclinic crystallites. The triclinic content is greater the higher the molecular weight of the sample and the higher the activity of the used catalyser. A melting / recooling treatment results in a reduction of crystallinity by about 15-25% and disappearance of the triclinic phase. Further, an irreversible conversion of nascent orthorhombic extended chain crystallites to orthorhombic folded chain crystallites of increased lateral dimensions and crystalline perfections takes place during the melting / recooling treatment. The results are compared to those obtained for lower-molecular-weight PE samples and for high-strength / modulus PE fibers of different origins.

Zusätzliches Material: 3 Tab.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/app.1991.070420332

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4

Digitale Medien

Preparation of spermatogenic cell populations at specific stages of differentiation in the human (1991)

Blanchard, Y. ; Lavault, M. T. ; Quernee, D. ; [weitere]

New York, NY [u.a.] : Wiley-Blackwell

Molecular Reproduction and Development 30 (1991), S. 275-282

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ISSN: 1040-452X

Schlagwort(e): Human testis ; Cell separation ; Elutriation ; Spermatid ; Ultrastructure ; Life and Medical Sciences ; Cell & Developmental Biology

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Biologie

Notizen: Studying biochemical events in human spermatogenesis requires separated populations of spermatogenic cells. Dissociation of these cells was performed by a Trypsin-DNAse method adapted from the technique used for rodents. Cell separation was performed by centrifugal elutriation. Seven populations were collected, one further purified by Percoll gradient centrifugation, giving nine different cell populations. The efficiency of the cell separation was evaluated by phase contrast microscopy, flow cytometric DNA analysis, and electron microscopy. Five populations were enriched in spermatids: two in round spermatids (87% and 73%), another in round (52%) and elongating (44%) spermatids, another constituted by 80% elongating spermatids, and the last by 90% elongated spermatids. Two of the four remaining populations were enrichied in primary spermatocytes (74% and 54%); another population was the upper part of the Percoll gradient and constituted cytoplasmic lobes and residual bodies (89%); the last population was made up of various cells, with no specific enrichment. Electron microscopic observations revealed good preservation of the separated cells; only the flagella from elongated spermatids were lost. Furthermore, an unusual pattern of nucleoplasm distribution during stages 2-4 of spermatid differentiation was observed and its signification is discussed with regard to the shape of the human spermatozoon.

Zusätzliches Material: 3 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/mrd.1080300316

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5

Digitale Medien

The influence of charge density and steric factor of aminated chloromethyl polystyrene homologs in bilirubin adsorption (1991)

Raghavan, D. ; Shaligram, A. M. ; Deshpande, D. D.

New York, NY [u.a.] : Wiley-Blackwell

Journal of Applied Polymer Science 42 (1991), S. 2483-2488

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ISSN: 0021-8995

Schlagwort(e): Chemistry ; Polymer and Materials Science

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie , Maschinenbau , Physik

Notizen: Bilirubin, a bile pigment, was studied for its extent of adsorption on substituted aminechloromethyl polystyrene by UV spectrophotometry. By performing simple displacement reactions on chloromethyl polystyrene with secondary and tertiary amines, the amount of charge density and steric factor on substituted nitrogen atom have been varied. Adsorption isotherms of bilirubin at 0°C by different amine-chloromethyl polystyrene homologs suggest the existence of electrostatic interaction of polymeric resin with bilirubin moiety. Results of adsorption of bilirubin to polymeric resin have shown that the extent of adsorption of bilirubin depends on the unit charge, and on the structure of the substituted amine-chloromethyl polystyrene. The effects of porosity of resin on bilirubin adsorption have also been discussed.

Zusätzliches Material: 7 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/app.1991.070420913

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6

Digitale Medien

Deterioration of plastic films under soil burial conditionsIssued as N.R.C.C. # 18807. (1981)

Colin, G. ; Cooney, J. D. ; Carlsson, D. J. ; [weitere]

New York, NY [u.a.] : Wiley-Blackwell

Journal of Applied Polymer Science 26 (1981), S. 509-519

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ISSN: 0021-8995

Schlagwort(e): Chemistry ; Polymer and Materials Science

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie , Maschinenbau , Physik

Notizen: The deterioration of polyolefin, poly(ethylene terephthalate), and polyamide films under soil burial conditions extending up to 32 months has been investigated. Based on changes in their elongation at break, the films can be ranked in order of increasing sensitivity to degradation: Polyester ≃ polypropylene 〈 low-density polyethylene ≃ high-density polyethylene 〈 nylon 6.6. The degraded nylon 6.6 and polyethylene films were characterized by infrared and luminescence spectroscopy and scanning electron microscopy, as well as by wet analysis for hydroperoxides. From a comparison with the well-known oxidative sensitivity of nylon 6.6 in oxygenated water at slightly elevated temperatures, the rapid deterioration of nylon 6.6 film during soil burial was also concluded to be an oxidative process. The somewhat smaller, but significant, embrittlement of the polyethylenes studied could not be simply explained by thermal oxidation (with only trace oxidation products detectable) or microbiological attack (deterioration being unaffected by surface activation to enhance wettability).

Zusätzliches Material: 5 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/app.1981.070260211

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7

Digitale Medien

Inhibition of the metabolism of ram spermatozoa by derivatives of α-chlorohydrin (1981)

Brown-Woodman, P. D. C. ; White, I. G. ; Ridley, D. D.

New York, NY : Wiley-Blackwell

Gamete Research 4 (1981), S. 203-217

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ISSN: 0148-7280

Schlagwort(e): α-chlorohydrin ; antifertility agent ; ram ; sperm metabolism ; Life and Medical Sciences ; Cell & Developmental Biology

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Biologie

Notizen: The effects of the male antifertility agent, α-chlorohydrin, six of its derivatives, and glycidol were studied on the metabolism of washed ram spermatozoa in vitro with fructose as substrate. The α-chlorohydrin derivatives were the amino, the phosphorylated, and four glycol-bridge (ketal) compounds. All compounds except glycidol, in a concentration between 0.1 and 100 mM, reduced the aerobic glycolsis and/or oxidation of fructose. However, there was not a high correlation between the ability of these compounds to inhibit the metabolism of ram spermatozoa in vitro and their antifertility activity when administered to male rats. Other factors are clearly involved in their antifertility activity, eg, the concentration of the compounds in the epididymis and their conversion of either more or less spermicidal compounds in the body.

Zusätzliches Material: 1 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/mrd.1120040305

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8

Digitale Medien

Aromatic polyamides. II. Thermal degradation of some aromatic polyamides and their model diamides (1981)

Khanna, Y. P. ; Pearce, E. M. ; Smith, J. S. ; [weitere]

New York : Wiley-Blackwell

Journal of Polymer Science: Polymer Chemistry Edition 19 (1981), S. 2817-2834

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ISSN: 0360-6376

Schlagwort(e): Physics ; Polymer and Materials Science

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie

Notizen: Thermal degradation behavior of poly(1,3-phenylene isophthalamide) and poly(chloro-2,4-phenylene isophthalamide) was investigated with the aid of some appropriate model compounds. The pyrolysis products of these materials were identified by gas chromatography (GC), gas chromatography/Fourier transform infrared spectroscopy (GC/FT-IR), and gas chromatography/mass spectrometry (GC/MS). The residual chars were characterized by IR spectroscopy. Thermogravimetric analysis (TGA) was applied to study the effect of end-group concentration on the degradation characteristics of the two polyamides. Kinetic parameters that describe the thermal degradation of the polyamides were also evaluated by TGA. The results of this investigation suggest that the thermal decomposition of these aromatic polyamides involves homolytic as well as hydrolytic cleavages of the amide units.

Zusätzliches Material: 13 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/pol.1981.170191115

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9

Digitale Medien

Spectroscopic studies of solutions, suspensions, and precipitates of poly(1,6-di-p-toluene sulfonyloxy-2,4-hexadiyne) (1981)

Bloor, D. ; Batchelder, D. N. ; Ando, D. J. ; [weitere]

New York : Wiley-Blackwell

Journal of Polymer Science: Polymer Physics Edition 19 (1981), S. 321-334

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ISSN: 0098-1273

Schlagwort(e): Physics ; Polymer and Materials Science

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie , Physik

Notizen: Optical-absorption, fluorescence, and Raman spectra for solutions, suspensions, and precipitates of poly(1,6-di-p-toluene sulfonoxy-2,4-hexadiyne) in and from nitrobenzene, acetone, and chloroform are presented. These are interpreted in terms of the occurrence of two forms of the polymer chain; a quasicrystalline form with properties close to those of single crystal polymer and a chain-extended form occurring in solution and colloidal particles, with an absorption energy of about 2.5 eV (20,000 cm-1). No evidence is found for the presence of very short polymer chains in partially polymerized monomer at low conversion. The relationship of these results to those for deformed single crystals is briefly discussed.

Zusätzliches Material: 9 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/pol.1981.180190212

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10

Digitale Medien

Developmental protein synthesis is required for the transcription of Dictyostelium prespore genes (1991)

Benedict, M. A. ; Desilver, D. A. ; Pelletier, D. E. ; [weitere]

Chichester [u.a.] : Wiley-Blackwell

Developmental Genetics 12 (1991), S. 113-122

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ISSN: 0192-253X

Schlagwort(e): Dictyostelium discoideum ; cyclo heximide ; emetine ; protein synthesis ; mRNA accu mulation ; transcription ; Life and Medical Sciences ; Genetics

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Biologie

Notizen: It has been established previ- ously that the maintenance of expression of pre-spore-specific genes of Dictyostelium discoideum is prevented by the translational inhibitor cyclohex- imide. The drug had no effect upon the level of transcripts of the other genes examined, prestalk-specific or cell type-nonspecific. However, the interpretation of this result is open to question, because of possible nonspecific effects of cyclo-heximide. We have now characterized the cellular specificity and temporal profiles of mRNA accumu- lation of additional Dictyostelium cDNA clones, and have examined other inhibitors of in vivo protein synthesis. Four structurally and mechanistically distinct translational inhibitors each prevented the reaccumulation of prespore transcripts in cyclic AMP-primed, disaggregated amoebae. These results establish the importance of developmental protein synthesis in the accumulation of prespore gene transcripts. Nuclear run-on transcription assays were used to learn whether protein synthesis is required primarily for mRNA synthesis or transcript stability. A transcriptional time course first demonstrated that the abundance of these cell-specific transcripts during development mirrors their rates of synthesis. Significantly, the protein synthesis requirement of the prespore genes examined also occurs at the level of mRNA transcription, implying the existence of one or more developmentally regulated transcriptional activators.

Zusätzliches Material: 6 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/dvg.1020120119

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