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  • Polymer and Materials Science  (13)
  • Cell & Developmental Biology  (10)
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  • 1
    Electronic Resource
    Electronic Resource
    Cleavage and 3H-uridine incorporation in bovine embryos of high in vitro developmental potential (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 39 (1994), S. 375-383 
    Details
    ISSN: 1040-452X
    Keywords: In vitro fertilization ; Bovine ; Embryo ; Genome Activation ; Transcription ; 3H-Uridine ; α-Amanitin ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The timing of genome activation in bovine embryos is still not well defined. The objective of this study was therefore to investigate transcription in bovine embryos with a high potential to develop in culture after in vitro fertilization, by examining, autoradiographically, their incorporation of 3H-uridine. Initial experiments determined that developmental potential in vitro could be related to the time of first division of the zygote. Embryos that completed their first cleavage within 30 hours of exposure to sperm were more likely to develop into blastocysts (65.7%) and to hatch (50.9%). Using such embryos, it was found that 10 of 12 8-cell and all 11 4-cell stage embryos were labeled after a 2-4-hr exposure to 3H-Uridine. Among 2-cell stage embryos, 0 of 23, 3 of 17, 8 of 15, and 3 of 4 were labeled after exposure to 3H-uridine of 2, 4, 7, and 10 hr, respectively. Treatment with α-amanatin (10-100 m̈g/ml) blocked 3H-uridine incorporation but did not inhibit cleavage during the first 4 cell cycles. It was concluded that transcription occurs as early as the 2-cell stage in bovine embryos in vitro but is not critical to the first four cell cycles. © 1994 Wiley-Liss, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1080390405
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  • 2
    Electronic Resource
    Electronic Resource
    Principles of specificity and redundancy underlying the organization of the olfactory system (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Microscopy Research and Technique 24 (1993), S. 106-112 
    Details
    ISSN: 1059-910X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jemt.1070240203
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  • 3
    Electronic Resource
    Electronic Resource
    Influence of recipient oocyte cell cycle stage on DNA synthesis, nuclear envelope breakdown, chromosome constitution, and development in nuclear transplant bovine embryos (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 36 (1993), S. 33-41 
    Details
    ISSN: 1040-452X
    Keywords: Cell cycle ; DNA synthesis ; NEBD ; Nuclear transplantation ; Bovine ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Nuclear transplantations into metaphase II (MII) and S phase oocyte cytoplasm were performed to investigate the influence of recipient cell cycle stage on nuclear function and development of bovine nuclear transplant (NT) embryos. Rate of inactivation of histone H1 kinase and duration of DNA synthesis in activated oocytes were determined. The proportion of S phase blastomeres in in vivo produced day 5.5 bovine embryos was measured. DNA synthesis was also assessed in NT embryos after transfer into MII and S phase cytoplasm. MII NT embryos were produced by fusing a blastomere into a MII oocyte; the fusion pulse served to activate the oocyte. S NT embryos were produced by fusing a blastomere into an early S phase oocyte electrically activated 4 h prior to fusion. Nuclear envelope structure, chromosome constitution, and extent of development were examined in MII and S NT embryos. Histone H1 kinase activity dropped to baseline within 2 h of electrical activation. A second electrical pulse did not alter H1 kinase activity when delivered 4 h after the first pulse. The frequency of S phase blastomeres in day 5.5 bovine embryos ranged from. 79% to 100%, depending on the duration of culture in 3H-thymidine. Nuclear transplantation into MII cytoplasm resulted in a transient drop in DNA synthesis over 3.5 h. DNA synthesis resumed at 4.5 h post activation (hpa), concomittantly with initiation of DNA replication in activated oocytes. In contrast, DNA synthesis was not interrupted after transfer into S phase cytoplasm. DNA synthesis persisted until 13.5 hpa, as in activated oocytes. Partial or complete nuclear envelope breakdown (NEBD) occurred after transfer into MII cytoplasm, whereas the nuclear envelope remained intact in 50% of the embryos or underwent partial breakdown in S phase cytoplasm. A greater proportion of S NT embryos was diploid (50% vs. 23% MII NT embryos, P 〈 0.001), and a higher frequency of S NT embryos developed to the morula or blastocyst stage (22% vs. 5%, P 〈 0.001). The data indicate that DNA synthesis is regulated differently if the recipient oocyte is in MII or in S phase at the time of fusion. Extended DNA synthesis after transfer into MII cytoplasm suggests a re-replication of the donor chromatin. Re-replication, presumably, does not occur after transfer into S phase cytoplasm. Re-replication is likely to be a consequence of permeabilization of the nuclear envelope upon NEBD in MII cytoplasm. Improved regulation of DNA synthesis after transfer into S phase cytoplasm and reduced incidence of chromosome damage in the first cell cycle may have been responsible for increased frequency of development of S NT embryos to the morula/blastocyst stage. © 1993 Wiley-Liss, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1080360106
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  • 4
    Electronic Resource
    Electronic Resource
    An investigation of the effects of the molecular weight distribution on the sensitivity of positive electron resists (1976)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 20 (1976), S. 2367-2375 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The molecular weight distribution of two grades of poly(methyl methacrylate) was determined, and the solubility of that polymer in methyl ethyl ketone-2-propanol mixtures was studied. The effects of the molecular weight distribution of the polymer and the strength of the developing solvent on electron resist sensitivity were studied experimentally and compared with a computer model of the electron exposure process. The molecular weight and the molecular weight distribution were found to have a significant effect on the sensitivity of poly(methyl methacrylate) as an electron resist. Increased sensitivity is predicted for higher molecular weight and narrower molecular weight distribution.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1976.070200907
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  • 5
    Electronic Resource
    Electronic Resource
    Development of in situ blends of poly(p-oxybenzoate-co-p-phenyleneisophthalate) with other thermotropic liquid crystalline polymers (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 53 (1994), S. 575-586 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A new in situ polymerization method is discussed wherein monomers of the major component are polymerized in the presence of a preformed thermotropic liquid crystalline polymer (LCP). Poly(p-oxybenzoate-co-p-phenyleneisophthalate) (HIQ) was chosen for this study. HIQ is well known to have a narrow process window and to be difficult to process reproducibly, both drawbacks for a commercial product. An in situ polymerization of the HIQ monomers in the presence of a fully polymerized LCP, such as poly(4-oxybenzoate-co-6-oxy-2-naphthoate) (CO) results in the “CO-HIQ” in situ blend. The in situ blend exhibited reduced biphasic morphology and was more homogeneous than was HIQ. The glass fiber-filled CO-HIQ resin also featured improved melt flow and more reproducible mechanical properties than those of HIQ. The in situ blends were characterized by optical microscopy, 1H-NMR, and melt rheology. The effect of the LCP level on the morphology of the in situ blend is discussed. © 1994 John Wiley & Sons, Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1994.070530510
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  • 6
    Electronic Resource
    Electronic Resource
    CircadianThe term circadian derives from the Latin “circadiem” - about a day. activity rhythms in cockroaches. III. The role of endocrine and neural factorsThis third paper of a series includes some material which is part of a thesis presented to the Department of Biology of Princeton University (unpublished) in partial fulfillment of the requirements for the degree of Doctor of Philosophy. (1966)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 67 (1966), S. 473-486 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The control of circadian activity rhythms (diurnal rhythms) in insects has been suggested to result by periodic neuroendocrine secretions. More specifically, Harker ('56) claimed that the locomotor rhythm in the cockroach, Periplaneta americana, is timed by a secretory “clock” located in the subesophageal ganglion. Later experiments by Harker indicated that this “clock” function failed unless the retrocerebral organs were left intact; allatectomy was said (no evidence given) to abolish a rhythm. The procedure for demonstrating a “clock” function in the ganglion involved transplanting it from a rhythmic donor into the hemocoel of an arrhythmic host and observing that the host subsequently became rhythmic. This result (without explicit information about the phase of the rhythm) does not warrant the conclusion that the ganglion acts as a clock. Therefore, I have attempted to confirm and extend these important results. Employing techniques essentially identical to Harker's, and using the same species of roach, I have been unable to find any evidence to support the original claim: (1) in 20 test animals, implantation of ganglia from rhythmic donors failed to re-instate a rhythm, and (2) allatectomy (22 cases) or removal of the entire retrocerebral complex (20 cases) did not interfere with the rhythm.The results of another series of experiments show that the cockroach brain is involved in the control of the activity rhythm. When the brain is surgically bisected (mid-sagittal) through the pars intercerebralis, arrhythmic activity patterns are immediately evoked. These continue for many weeks, but in a few cases rhythms ultimately “regenerate”.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1040670312
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  • 7
    Electronic Resource
    Electronic Resource
    Mechanical properties of a hydrophilic acrylic polymer (1972)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 6 (1972), S. 15-24 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Acrylic polymers with hydrophilic groups (i.e., ethyl hydroxyl) may be prepared that convert to a soft elastic gel by absorbing water. Such a polymer has been applied to dentistry for use as an elastic lining material for dentures. A commercial product, Hydron, was used in this study. The linear expansion of this material after 520 hr of water immersion was found to be 20.4%. Hardness was found to decrease from 15.7 KHN for the dry polymer to 1.5 KHN at 19% absorbed water content. The swelling pressure was measured and found to reach a maximum value of 157 psi after 204 hr of water immersion. The Young's modulus was found to decrease from a value of 295,300 psi to 290 psi with 19% absorbed water content. Values were determined on intermediate water contents for the properties studied.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820060204
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  • 8
    Electronic Resource
    Electronic Resource
    The curing reaction of an epoxide resin with 2-ethyl-4-methylimidazole, a calorimetric study of the kinetics of formation of epoxide-imidazole adducts (1975)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 176 (1975), S. 919-930 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Kinetik der Bildung von 1:1 und 2:1-Addukten (bezogen auf die Äquivalente Epoxid) von 2,3-Epoxipropyloxybenzol (2) und 2,2-Bis[p-(2,3-epoxypropyloxy)phenyl]-propan (1) mit 2-Äthyl-4-methylimidazol (3) wurde mit Hilfe der Differentialkalorimetrie (DSC) untersucht. Ein Vergleich isothermer und dynamischer Werte des 1:1-Systems 2/3 zeigte, daß die dynamische Geschwindigkeit nicht einfach mit der isothermen Geschwindigkeit gleichgesetzt werden kann, wohingegen die wahre dynamische Geschwindigkeitsgleichung dα/dt = (∂α/∂tT)+(∂α/∂Tt) (dT/dt), gute Übereinstimmung mit den isothermen Werten ergab. Die dynamischen DSC-Messungen deuten darauf hin, daß alle Reaktionen angenähert nach der 1. Ordnung verlaufen und ähnliche Werte für die Aktivierungsenergie (E = 81-93 kJ/mol) und den Frequenzfaktor (log A ≈ 9-10) ergeben. Die Ergebnisse stützen den Vorschlag, daß die Adduktbildung wahrscheinlich die erste Stufe der durch 3 katalysierten Harzvernetzung darstellt.
    Notes: The kinetics of formation of the 1:1 and 2:1 adducts of (in terms of equivalents of epoxide) 2,3-epoxypropyloxybenzene (2) and 2,2-bis[p-(2,3-epoxypropyloxy)phenyl]-propane (1) with 2-ethyl-4-methylimidazole (3) have been investigated by differential scanning calorimetry (DSC). A comparison of isothermal and dynamic data for the 1:1 system 2/3 showed that the dynamic rate cannot simply be equated to the isothermal rate, but the true dynamic rate equation, dα/dt = (∂α/∂tT)+(∂α/∂Tt) (dT/dt), gave good agreement with the isothermal data. The dynamic DSC measurements indicate that all of the reactions approximate to first order kinetics and have similar values for activation energy (E = 81-93 kJ/mol) and pre-exponential factor (log A ≈ 9-10). The results support the suggestion that adduct formation is likely to be the first stage of the resin curing reaction catalyzed by 3.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1975.021760408
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  • 9
    Electronic Resource
    Electronic Resource
    Biosynthesis of the photosynthetic membranes of rhodopseudomonas sphaeroides (1983)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 22 (1983), S. 15-29 
    Details
    ISSN: 0730-2312
    Keywords: Rhodopseudomonas sphaeroides ; photosynthetic membrane synthesis ; cell cycle ; freeze fracture ; macromolecule distribution ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: The steady-state biosynthesis of the photosynthetic membrane (ICM) of Rhodopseudomonas sphaeroides has been reviewed. At moderate light intensities, 500 ft-c, preexisting ICM serves as the insertion matrix for newly synthesized membrane components. Whereas the bulk of the membrane protein, protein-pigment complexes, and pigments are inserted into preexisting ICM throughout the cell cycle, phospholipid is transferred from outside the ICM to the ICM only at the time of cell division. Because the site of cellular phospholipid synthesis is the cytoplasmic membrane, these results infer that despite the physical continuity of cytoplasmic membrane and ICM, there must exist between these membranous domains a “barrier” to the free diffusion of cellular phospholipid. The cyclical alternation in protein to phospholipid ratio of the ICM infers major structural and functional alternations, such as changes in the protein to lipid ratio of the membrane, specific density of the membrane, lipid structure within the membrane, and the rate of cyclic electron flow. When biochemical studies are correlated with detailed electron microscopic investigations we can further conclude that the number of photosynthetic units within the plane of the membrane can vary by nearly a factor of two over the course of the cell cycle. The average physical size of the photosynthetic units is constant for a given light intensity but inversely proportional to light intensity. The distribution of photosynthetic unit size classes within the membrane can be interpreted as suggesting that the “core” of the photosynthetic unit (reaction center plus fixed antenna complex) is inserted into the membrane coordinately as a structural entity. The variable antenna complex is, on the other hand, inserted independent of the “core” and randomly associates with both old and new core complexes. Finally, we conclude that there is substantial substructure to the distribution of photosynthetic units within the ICM, ie, they are highly ordered and exist in a defined spatial orientation to one another.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcb.240220103
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  • 10
    Electronic Resource
    Electronic Resource
    Use of cobalt complexes as activators in emulsion copolymerization of butadiene and styrene (1948)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 3 (1948), S. 181-194 
    Details
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Cobalt complex compounds exhibited varying degrees of activation and retardation in butadiene-styrene-soap emulsion polymerization systems at 20-50°C. An accompanying effect was the wasting of modifier, particularly by large concentrations of activator. The most active complexes for use with dodecyl mercaptan were those in which the cobalt was coordinated with two or more negative groups other than thiocyanate, and in which the neutral coordinated groups were not ethylenediamine.
    Additional Material: 17 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1948.120030205
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