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  • 1990-1994  (94)
  • Chemistry  (78)
  • Cell & Developmental Biology  (16)
  • crystal structure
  • 1
    Electronic Resource
    Electronic Resource
    Design and Synthesis of Novel Opiate Antagonists with LH-Stimulating Properties (1990)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 73 (1990), S. 326-336 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Opiate antagonists stimulate the release of LH and might, therefore, contribute to an innovative therapy for the treatment of numerous clinical syndromes characterized by hypofunction of the HHG axis. The purpose of this work was to design and synthesize pure opiate antagonists useful for this therapy. Me, Et, Pr, and PhCH2 groups were introduced at the crucial 14β-position of morphines and morphinans via a hetero-Diels-Alder key step starting from thebaine derivative 1 and tested for opiate antagonism and LH-stimulating activity. Me-, Et-, and Pr-substituted compounds 11a-c were stronger antagonists than naltrexone, whereas Pr and PhCH2 substituents in 11c, 11d, 9d, 9d3, 9d4, and 9d5 led to orally active LH stimulators. Based on our finding that the μ-antagonists 12 and 11b5 showed no LH stimulation, we conclude that a combination of both μ-and χ-antagonism is necessary for potent LH stimulation.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19900730212
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  • 2
    Electronic Resource
    Electronic Resource
    Reorganization of cytoskeletal and junctional proteins during cochlear hair cell degeneration (1991)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 18 (1991), S. 215-227 
    Details
    ISSN: 0886-1544
    Keywords: guinea pig ; organ of Corti ; cytokeratins ; actin ; cingulin ; phalangeal scar ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Experiments were carried out to elucidate changes in cytoskeletal elements and intercellular junctions in the organ of Corti, when hair cells degenerate and phalangeal scars form. Hair cell damage was induced by exposing guinea pigs to high intensity noise. The spatial and temporal changes in the organization of micro-filaments, intermediate filaments, and tight junction-specific proteins were investigated using scanning and transmission electron microscopy and histochemistry. The results show that microfilaments, cytokeratins, adherens junctions, and tight junctions rearrange their distribution in damaged areas. From the temporal sequence of these changes it appears that phalangeal scars develop simultaneous with hair cell degeneration, and that the integrity of the luminal membranes in the organ of Corti is not interrupted. Each scar is formed by two supporting cells which expand and invade the sub-apical region of the dying hair cell. This region becomes cytokeratin-positive. The two supporting cells meet at the mid-line of the scar, where a new junctional complex is formed. The junctional complex consists of tight junction and adherens-type junction, but desmosomes are absent.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970180307
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  • 3
    Electronic Resource
    Electronic Resource
    Excited states of CF4 plasma for polymerization of TMPTA monomer (1992)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 30 (1992), S. 323-328 
    Details
    ISSN: 0887-624X
    Keywords: CF4 plasma ; trimethylolpropane triacrylate ; excited states ; plasma induced polymerization ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The F and CF2-CF2+ excited states have been detected by emission spectroscopy in CF4RF plasmas used for TMPTA polymerization. These excited states are related through electron collision to F and CF2 ground states. The temporal variation of the F and CF2-CF2+ radiative states near the substrate reveals that the F atoms disappear first by incorporation in the monomer during the polymerization phase and, then, by a third body recombination process enhanced by the polymer surface. The CF2-CF2+ radiative states are varying as the inverse of the F states indicating a strong destruction mechanism of CF2 radicals by F atoms.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1992.080300217
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  • 4
    Electronic Resource
    Electronic Resource
    Metabolic regulation in mammalian sperm: Mitochondrial volume determines sperm length and flagellar beat frequency (1991)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 19 (1991), S. 180-188 
    Details
    ISSN: 0886-1544
    Keywords: spermatozoa ; cilia and flagella ; mechanochemical transduction ; dynein ; cell motility ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In the absence of glycolytic support, mammalian sperm derive their energy for motility from a densely packed array of mitochondria at the base of the flagellum known as the midpiece. Using data on the morphometric dimensions of over 200 mammalian species, we found that an allometric relationship exists between midpiece length (Lm) and flagellum length (Lf). Specifically, the length of the midpiece varies approximately as the 3/2 power of the flagellar length although the proportionality constant is different for eutherian and marsupial sperm. In contrast, when we corrected for the fraction of the midpiece that was taken up by mitochondria, a single linear correlation between mitochondrial volume and flagellar length for all mammals was found. These allometric relationships were used along with basic flagellar hydrodynamic theories to establish a unifying equation that predicted flagellar frequencies for any mammalian sperm between 40 μm and 200 μm in length. These findings imply that, at least in mammals, the mechanisms for energy production and dissipation in sperm flagella are highly conserved.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970190306
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  • 5
    Electronic Resource
    Electronic Resource
    Polymer drying. VII. 1H-NMR studies of evaporation from liquid saturated poly(styrene-co-divinylbenzene) (1992)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 30 (1992), S. 1155-1161 
    Details
    ISSN: 0887-624X
    Keywords: adsorption ; desorption ; association ; polystyrene ; NMR ; polymer transitions ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Composition-studies were carried out in which samples of films composed of poly(styrene-co-divinylbenzene) particles enmeshed by poly(tetrafluoroethylene) fibers were saturated with dichloromethane and then allowed to evaporate at 23°C to virtual dryness as the 1H-NMR signals and residual weight of sorbed liquid were monitored. The correlations, of 1H-NMR line-widths with the corresponding log of the number, αt of residual sorbed molecules per monomer unit show that sharp changes occur as αt passes through αG the composition that exists when all the liquid not sorbed (i.e., not present within the liquid-saturated particles), has been eliminated, and again as αt passes through αg the composition that exists when the particles attain the rigidity characteristic of the glassy state. Correlation of the corresponding T1 relaxation times with log αt show that sharp changes occur when αt becomes equal first to α′s and then to α′g the compositions that exist respectively when, firstly, all the sorbed liquid not immobilized by adsorption to the polymer chains within the particles has been eliminated, and then when the desorption of immobilized liquid from the chains causes the composition to begin to undergo transition from its rubbery state to its glassy state.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1992.080300622
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  • 6
    Electronic Resource
    Electronic Resource
    Effect of polarity of the medium on the stereospecific polymerization of propylene by ansa-zirconocene catalyst (1994)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 32 (1994), S. 2049-2056 
    Details
    ISSN: 0887-624X
    Keywords: metallocenes ; olefin polymerizations ; Ziegler-Natta catalysts ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Propylene was polymerized with rac-ethylene-bis (1-η5-indenyl)dichlorozirconium/methylaluminoxane in solvents of different polarity. The poly (propylene) formed was separated by solvent extraction; 13C-NMR and DSC measurements were made on the polymer fractions. The poly(propylene) in each solvent fraction has its characteristic molecular weight steric pentad distributions, melting transition temperature, and enthalpy for fusion irrespective of the polymerization medium. The results suggest that the medium dielectric constant does not affect the polymerization rate or the intrinsic stereoselectivity, propagation and chain transfer rates a given catalytic species but can alter the occurrence of steric insertion errors through shifting of distributions of the propagating species producing poly(propylenes) of different stereoregularities. © 1994 John Wiley & Sons, Inc.
    Additional Material: 7 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1994.080321106
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  • 7
    Electronic Resource
    Electronic Resource
    CO2/CH4 separation by facilitated transport in amine-polyethylene glycol mixtures (1993)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 39 (1993), S. 1135-1145 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In this work, the separation of carbon dioxide from methane by reactive liquid membranes consisting of the secondary amines, diethanolamine, and diisopropanolamine in polyethylene glycol with an average molecular weight of 400 was studied. A mathematical model was developed to describe the transport process. This model employs the zwitterion mechanism for the CO2 amine reaction kinetics. Membrane flux experiments utilizing a flat plate device were carried out to verify the model predictions. It was found that large permeabilities and separations were achieved for low CO2 feed concentrations. The results also show that DEA based solutions give better separation than DIPA based solutions.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690390706
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  • 8
    Electronic Resource
    Electronic Resource
    Biological sulfuric acid transformation: Reactor design and process optimization (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 41 (1993), S. 303-315 
    Details
    ISSN: 0006-3592
    Keywords: biological acid transformation ; sulfuric acid conversion ; sulfuric acid disposal ; sulfate-reducing bacteria ; dihydrogensulfide toxicity ; fixed-bed reactor ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: As an alternative to the current disposal technologies for waste sulfuric acid, a new combination of recycling processes was developed. The strong acid (H2SO4) is biologically converted with the weak acid (CH3COOH) into two volatile weak acids (H2S, H2CO3) by sulfate-reducing bacteria. The transformation is possible without prior neutralization of the sulfuric acid. The microbially mediated transformation can be followed by physiochemical processes for the further conversion of the H2S.The reduction of sulfate to H2S is carried out under carbon-limited conditions at pH 7.5 to 8.5. A fixed-bed biofilm column reactor is used in conjunction with a separate gas-stripping column which was installed in the recycle stream. Sulfate, total sulfide, and the carbon substrate (in most cases acetate) were determined quantitatively. H2S and CO2 are continually removed by stripping with N2. Optimal removal is achieved under pH conditions which are adjusted to values below the pKa-values of the acids. The H2S concentration in the stripped gas was 2% to 8% (v/v) if H2SO4 and CH3COOH are fed to the recycle stream just before the stripping column.Microbiol conversion rates of 65 g of sulfate reduced per liter of bioreactor volume per day are achieved and bacterial conversion efficiencies for sulfate of more than 95% can be maintained if the concentration of undissociated H2S is kept below 40 to 50 mg/L. Porous glass spheres, lava beads, and polyurethane pellets are useful matrices for the attachment of the bacterial biomass. Theoretical aspects and the dependence of the overall conversion performance on selected process parameters are illustrated in the Appendix to this article. © 1993 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260410304
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  • 9
    Electronic Resource
    Electronic Resource
    Tomographic Techniques for Characterising Particulate Processes (1993)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 10 (1993), S. 252-261 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A review of existing and developing process tomographic instrumentation suitable for characterising dry and wet particulate systems is presented. Factors governing the selection of sensing techniques appropriate for static and dynamic imaging of a wide range of single and multiphase particulate processes are discussed. The paper presents a systematic comparison of different image reconstruction methods. Examples of existing, developing and proven applications are cited. Future needs and ways in which these needs can be met are suggested, including the use of multi-modality methods in which different types of sensing methods are embodied in a single tomographic instrument.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19930100507
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  • 10
    Electronic Resource
    Electronic Resource
    Letter to the editor (1993)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 16 (1993), S. 52-52 
    Details
    ISSN: 0935-6304
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240160110
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