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  • Polymer and Materials Science  (495)
  • SOLAR PHYSICS  (161)
  • Life and Medical Sciences  (129)
  • 1980-1984  (785)
  • 1984  (374)
  • 1983  (411)
Collection
Publisher
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  • 1980-1984  (785)
Year
  • 1
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 17 (1983), S. 59-70 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Porous high-density polyethylene specimens were implanted in the femurs of mongrel canines. At the end of the residency period (3 or 6 months), the animals were sacrificed and the implants were retrieved. The work-of-fracture of the implant specimens was then determined using the technique of Tattersall and Tappin. The work required to fracture a specimen in three-point bending by controlled crack propagation through a triangular cross section was obtained directly from the load-deflection curve. The area of the resulting fracture surface was measured by macro-photographic techniques, and the work-of-fracture was calculated as work per unit area. The implants were subsequently sectioned and examined microradiographically to determine the extent of bone ingrowth. Bone specimens adjacent to the implants and porous high-density polyethylene controls (no ingrowth) were also tested to determine their work-of-fracture. The results showed that bone adjacent to the implant specimens had a higher work-of-fracture than normal medial, canine femoral bone and was not appreciably different from the composite. The work-of-fracture of porous high-density polyethylene was not significantly increased by an increase in bone infiltration, and this anomalous behavior was attributed to a degradation of the polyethylene during implant residence. Control studies supported this hypothesis.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0148-7280
    Keywords: spermatozoa ; flow cytometry ; DNA staining ; nuclear morphology ; ultrastructure ; mammals ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The morphological and ultrastructural changes that occur during preparation of porcine, bovine, and murine spermatozoa for flow cytometric quantification of the relative DNA content of the X- and Y-chromosome-bearing sperm populations were examined. Ejaculated spermatozoa from the boar and bull were washed using a series of dimethyl sulfoxide (DMSO) solutions prior to fixation, whereas the epididymal mouse spermatozoa were washed only in phosphate-buffered saline (PBS). Spermatozoa from all three species were then fixed in ethanol and processed for fluorochrome staining by a treatment regimen consisting of sulfhydryl reduction and proteolysis. The processed sperm nuclei were stained for DNA with the fluorochrome, 4′-6-diamidino-2-phenylindole (DAPI) before quantification by flow cytometry. Scanning and transmission electron micrographs of sperm heads taken at various steps of the preparation and staining procedures show 1) that the rigorous washing procedure disrupted the plasma and outer acrosomal membranes, 2) that ethanol fixation resulted in removal of the outer membranes and disintegration of the nuclear envelope, and 3) that thiol and proteolysis treatment removed the remaining cellular organelles including the tail and rapidly induced partial decondensation of the tightly packed chromatin. Sequential micrographs showed that the nuclear matrix of all three species increased in thickness about twofold during the preparation and staining. Consequently, the harsh procedures currently used for quantitative staining of DNA for high-resolution flow cytometric analyses destroy most cellular organelles and thereby prevent simultaneous characterization of DNA content and other sperm cell constituents.
    Additional Material: 6 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Fire and Materials 7 (1983), S. 79-88 
    ISSN: 0308-0501
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: There are two major fire processes, an understanding of which is essential for effective fire safety design: (1) the conditions under which a combustible material may become involved in flaming combustion, and (2) the rate at which such a material, once involved, will provide an output of heat, smoke, toxic gases, etc., which can endanger people and property. The first process may be regarded as covering both ignition and spread of fire on materials; its complement is the way in which fire may become extinguished. It is necessary for such processes to bring in a characteristic of the basic combustion reaction which, directly or indirectly, expresses the reactivity of the combustion process. Thus pilot ignition is usually associated with an approximate surface fuel temperature. More basically, it is associated with a critical flow rate of volatiles and a critical heat loss from the flame, the latter being influenced by ambient oxygen and temperatures conditions as well as heat lost and gained by the fuel itself. The most important factor governing the production of dangerous product is the rate at which volatiles first (fuel controlled fires) and later air (air controlled fires) are fed into the flames. The reactivity is of less importance, although it may be one of the factors which control combustion efficiency. In general, the more efficient is the combustion the more heat is produced, but the less smoke and toxic gases are produced. Some of the main advances in the above areas are reviewed in this paper.
    Additional Material: 2 Ill.
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  • 4
    Publication Date: 2019-06-28
    Description: Absorption features from the 8 micron SiO fundamental (upsilon = 1-0) and hot bands (upsilon = 2-1) have been observed in sunspots at sub-Doppler resolution using a ground-based tunable diode laser heterodyne spectrometer. The observed line widths suggest an upper limit of 0.5 km/s for the microturbulent velocity in sunspot umbrae. Since the silicon monoxide abundance is very sensitive to sunspot temperature, the measured equivalent widths permit an unambiguous determination of the temperature-pressure relation in the upper layers of the umbral atmosphere. In the region of SiO line formation (log P sub g = 3.0-4.5), the results support the sunspot model suggested by Stellmacher and Wiehr (1970).
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 269; June 1
    Format: text
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  • 5
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Human fibrinogen was treated with thrombin in the presence of fibrinoligase (Factor XIIIa) and calcium ion at pH 8.5, ionic strength 0.45, and the ensuing polymerization was interrupted at various time intervals (t) both before and after the clotting time (tc) by solubilization with a solution of sodium dodecyl sulfate and urea. Aliquots of the solubilized protein were subjected to gel electrophoresis on polyacrylamide gels after disulfide reduction by dithiothreitol and on agarose gels without reduction. The degree of γ-γ ligation was determined from the former. The latter provided the size distribution of ligated end-to-end sequences produced by splitting the ligated staggered overlapped oligomers down the middle, for degrees of polymerization, x, from 1 to 10. Addition of fibrinoligase (in which the activating thrombin had been inhibited by p-nitrophenyl-p′-guanidinobenzoate, NPGB) to Kabi fibrinogen showed the presence of small amounts of ligatable oligomers. Addition of fibrinoligase to a polymerizing mixture in which the action of thrombin had been stopped before clotting by NPGB produced the same distribution of ligated end-to-end sequences that was obtained when fibrinoligase was originally present, at least for reaction times up to 0.7 of the clotting time. The kinetics of γ-γ ligation by fibrinoligase acting on a polymerized mixture stabilized by NPGB were followed. The reaction was first order in the concentration of ligatable γ-γ junctions and the initial velocity was proportional to the enzyme concentration. The time evolution of size distribution of ligated end-to-end sequences agreed with a theory based on random ligation of ligatable junctions.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 22 (1983), S. 1489-1498 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Empirical force-field calculations and ir and 1H-nmr spectra indicate that five-membered (C5) and seven-membered (C7eq) hydrogen-bonded rings are the preferred conformations of acetyl-L-Phe p-acetyl and p-valeryl anilides in nonpolar media. The C5/C7eq ratio was found to be dependent on the dryness of the solute and the solvent. This fact and the results from conformational-energy calculations suggest that a molecule of water participates in the stabilization of the C7eq conformation.
    Additional Material: 4 Ill.
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  • 7
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Biocompatible, biodegradable copolymers of glutamic acid and ethyl glutamate were evaluated for their permeability to proteins ranging in molecular weight from 12,300 to 69,000. The results showed that the copolymers were sufficiently permeable that they could be used for the preparation of implantable, controlled-release systems capable of releasing therapeutic amounts of high-molecular-weight drugs.
    Additional Material: 7 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 2067-2081 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Resonance Raman spectra of the nucleoside 5′-monophosphates UMP, CMP, AMP, and GMP have been obtained with 266- and 213-nm radiation, the fourth and fifth harmonics of a Nd:YAG laser. The 266-nm radiation is resonant with the states giving rise to the first absorption band of the bases. The resulting spectra are in agreement with those reported previously using similar wavelength excitation but are generally of better quality. The 213-nm radiation is resonant with those states giving rise to the second strong absorption band of the bases. The spectra obtained with this wavelength show several new features relative to the 266-nm spectra, including strong enhancement of modes of the pyrimidines with a character similar to the e2g ν8 mode of benzene, relative enhancement of ring modes at 1580 and 729 cm-1 in AMP, and strong enhancement of the 1670-cm-1 C = O mode of GMP. These enhancements are discussed in terms of previously reported preresonance behavior and predicted intensities based on CNDO bond-order changes and normal-mode calculations. The results of a preliminary study of the effect of the interaction of GMP with cis-dichlorodiammineplatinum(II) on the 213-nm resonance Raman spectrum is also discussed.
    Additional Material: 8 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 2157-2172 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The effects of organic solvents on the 31P-mr chemical shifts of various phosphate diesters have been investigated in water and mixed-organic solvent systems. The addition of organic solvents to cyclic phosphates and to diethyl phosphate causes large upfield shifts of the phosphorus resonance which are attributed to solvent-induced changes in the local hydration of the phosphodiester group. This is consistent with the fact that there is an inverse correlation between the hydrogen-bond-donating ability of the solvents and the magnitude of the shifts they induce. Other possible interpretations, such as solvent-induced ion pairing and solvent-induced conformational changes, appear to be eliminated. Fourier-transform ir study of the cyclic nucletides reveals that there are also large solvent-induced shifts in the frequency of the antisymmetric OPO stretching frequency, and a comparison of the two types of measurements indicates that there is a linear correlation between shifts observed in the ir and in the 31P-nmr spectra. With UpU, the solvent-induced 31P-nmr shifts are ∼3 times smaller than those observed with the cyclic phosphates and the solvent-induced shift of the OPO band is reduced (factor of ∼1.7) as compared with the cyclic phosphates. With the single-stranded polynuclotides, poly(C) and poly(U), the solvent-induced shifts in both the nmr and ir are quite small (∼0.1 ppm and ∼1 cm-1). The very small solvent effects observed with poly(U) and poly(C) are attributed to a combination of steric effects and a polyelectrolyte effect which maintains a high density of counterions with waters of hydration in the vicinity of the charged backbone and makes the phosphates much less susceptible to solvent-induced changes in hydration.
    Additional Material: 7 Ill.
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  • 10
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 24 Ill.
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