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  • 1995-1999  (35)
  • 1970-1974
  • 1960-1964
  • 1997  (35)
  • 1
    Electronic Resource
    Electronic Resource
    Noise in wavelength conversion using four-wave mixing in semiconductor optical amplifiers (1997)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 70 (1997), S. 306-308 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We measure the pump power dependence of efficiency and signal-to-background ratio in wavelength conversion using four-wave mixing in semiconductor optical amplifiers, for different lengths of the device. We show that the efficiency for a 1-mm-long amplifier is about 40 dB larger and the signal-to-noise ratio is about 23 dB larger than for a 0.25 mm amplifier. We also show that, unlike the efficiency, for constant ratio between pump- and signal-power, the signal-to-background ratio monotonically increases with the pump power. We show theoretically that this behavior holds for any range of pump-power values. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.118400
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  • 2
    Electronic Resource
    Electronic Resource
    X-ray diffraction and x-ray photoelectron spectroscopy study of partially strained SiGe layers produced via excimer laser processing (1997)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 82 (1997), S. 147-154 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Structural properties of graded Si(1−x)Gex layers obtained on Si(100) by pulsed laser induced epitaxy were investigated by means of conventional powder x-ray diffraction and x-ray photoelectron spectroscopy. The Si(1−x)Gex epitaxial layers were formed by pulsed KrF-laser driven rapid melting and crystallization of thin amorphous Ge layers deposited onto the Si(100). The experimental results showed that, by increasing the number of laser pulses, good quality and partially strained epitaxial layers could be attained. A Monte Carlo data evaluation algorithm is proposed, which is capable to determine, by the simultaneous fit of data obtained by x-ray diffraction and x-ray photoelectron spectroscopy, the strain level as a function of Ge concentration. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.365793
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  • 3
    Electronic Resource
    Electronic Resource
    A novel solid state battery based on a polymer proton conductor: poly(propargyl alcohol) doped with perchloric acid (1997)
    Springer
    Journal of applied electrochemistry 27 (1997), S. 862-866 
    Details
    ISSN: 1572-8838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract A battery was constructed by including a polymer proton conductor, poly(propargyl alcohol) doped with perchloric acid, between electrodes of magnesium and gold. The characteristics of the cell, showing an open circuit voltage of 2.0–2.2V, were studied as the function of the relative humidity. It was found that the system behaves as a fuel cell and that the discharge current of the battery is due to magnesium oxidation at the anode and proton reduction at the cathode.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018485131407
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  • 4
    Electronic Resource
    Electronic Resource
    Subnuclear localization of S/MAR-binding proteins is differently affected by in vitro stabilization with heat or Cu2+ (1997)
    Springer
    Chromosoma 106 (1997), S. 81-93 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. The nuclear matrix, a proteinaceous entity thought to be a scaffolding structure that determines the higher order organization of eukaryotic chromatin, is usually prepared from intact nuclei by a series of extraction steps. In most cell types investigated, the nuclear matrix does not spontaneously resist these extractions, but must rather be stabilized before the application of extracting agents such as high salt solutions or lithium diiodosalicylate. We have examined the effect of two widely used stabilization procedures on the localization of nuclear matrix proteins. Four individual polypeptides were studied, all of which are scaffold or matrix-associated region (S/MAR)-binding proteins: SATB1, SAF-A/hnRNP-U, NuMA , and topoisomerase II α. Nuclei were isolated from K562 human erythroleukemia cells in a buffer containing spermine, spermidine, KCl and EDTA, and the nuclear matrix or scaffold was obtained by extraction with lithium diiodosalicylate after stabilization by heat treatment (37° or 42°C) or incubation with Cu2+ ions. When the localization of individual proteins was determined by immunofluorescent staining and confocal scanning laser microscopy, markedly different consequences of the two stabilization strategies became evident, ranging from a total maintenance of the localization (NuMA and topoisomerase II α) to a marked redistribution (SATB1 and SAF-A/hnRNP-U). Our results seem to indicate that a reevaluation of stabilization protocols employed for the preparation of the nuclear matrix is desirable, especially by performing morphological controls.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004120050227
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  • 5
    Electronic Resource
    Electronic Resource
    The nuclear matrix and apoptosis (1997)
    Springer
    Histochemistry and cell biology 108 (1997), S. 1-10 
    Details
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  Apoptosis is a form of active cell death, genetically encoded, that plays a key role during several physiological and pathological conditions. During the apoptotic process, striking morphological and biochemical changes take place in the cell nucleus. However, the molecular mechanisms underlying these changes have escaped clarification for many years. Recently, attention has been devoted to identifying the modifications that occur during apoptosis in the nuclear matrix, a mainly proteinaceous framework structure which is thought to play a fundamental role in organizing nuclear structure and function. In this review, we focus our attention on the biochemical and morphological changes detected in the nuclear matrix during the apoptotic process. Particular emphasis will be placed on the proteolysis that some nuclear matrix proteins undergo early during the apoptotic process, as well as on the detachment of DNA loops from the matrix by the action of endonuclease(s). Future research in this field may provide important information about the principal mechanisms that cause nuclear destruction in apoptotic cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004180050140
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  • 6
    Electronic Resource
    Electronic Resource
    Changes in the subnuclear distribution of two RNA metabolism-related proteins can be detected in nuclear scaffold or matrix prepared by different techniques (1997)
    Springer
    Histochemistry and cell biology 108 (1997), S. 525-536 
    Details
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  The nuclear scaffold or matrix is a mainly proteinaceous structure thought to act as a nucleoskeleton determining the higher order organization of eukaryotic chromatin. These structures are prepared from isolated nuclei by a series of extraction steps involving the use of ionic detergents or high salt, and restriction enzymes or non-specific nucleases to remove chromatin and other loosely bound components. Since these treatments are harsh and unphysiological, the question remains open as to whether or not these structures, isolated in vitro, correspond to a nucleoskeleton existing in vivo. Recently, it has been demonstrated that the majority of nuclear matrix proteins are involved in RNA metabolism. In this study we have employed a morphological approach involving the use of confocal laser scanning microscopy and indirect immunofluorescence techniques to analyze whether two widely employed methods to prepare the nuclear scaffold or matrix can maintain the spatial distribution of two polypeptides involved in RNA metabolism, i.e., a 105-kDa component of spliceosomes and a ribonucleoprotein antigen. We demonstrate that the localization of these polypeptides changes, in some cases dramatically, in the final nucleoskeletal structures when compared with intact cells. Only when isolated nuclei were stabilized in vitro with the cross-linking agent sodium tetrathionate (NaTT) prior to extraction with 2 M NaCl and DNase I digestion, were the immunofluorescent patterns displayed by the nuclear matrix indistinguishable from those detected in intact cells. These results emphasize the usefulness of NaTT in studying putative nucleoskeletal structures, but also show that the methods currently employed to prepare the nuclear scaffold or matrix may create in vitro artifacts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004180050193
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  • 7
    Electronic Resource
    Electronic Resource
    Synthesis of TiC and SiC/TiC nanocrystalline powders by gas-phase laser-induced reaction (1997)
    Springer
    Journal of materials science 32 (1997), S. 5629-5635 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract In the development of advanced ceramic nanocomposites, the production of titanium-based nanopowders has assumed importance, especially since recent results showed that mechanical properties of SiC matrices could be significantly improved by the incorporation of TiC second phase and vice versa. Nanosized TiC and TiC/SiC powders were synthesized by CO2 laser-induced reactions. A TiCl4 and hydrocarbons mixture was irradiated for titanium carbide production; the addition of SiH4 gave rise to the composite powders. The results of the powder characterization, obtained mainly by X-ray photoelectron spectroscopy, X-ray-induced Auger Spectroscopy and X-ray diffraction, are discussed in detail to correlate the reaction parameters to the composition and morphology of the products. Both TiC and SiC/TiC nanopowders showed a high reactivity to the air exposure, as evinced by the surface oxidation of the particles. Nevertheless, a quite good yield was obtained for nanocomposites of β-SiC matrix with the addition of up to 20% TiC phase.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018640911556
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  • 8
    Electronic Resource
    Electronic Resource
    Stereochemistry and antitumour activity of platinum metal complexes of 2-acetylpyridine thiosemicarbazones (1997)
    Springer
    Transition metal chemistry 22 (1997), S. 263-269 
    Details
    ISSN: 1572-901X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Complexes, [M(HL)2], where M = PdII, PtII and HL = neutral 2-acetylpyridine-(2-methylthiosemicarbazone), 2-acetylpyridine-(4-methylthiosemicarbazone) and 2-acetylpyridine-(4-phenylthiosemicarbazone), as well as [M(HL)2]Cl3, where M = RuIII, RhIII and IrIII, have been prepared and characterized by elemental analyses, conductivity measurements, magnetic susceptibility measurements and spectroscopic (i.r., Raman, u.v.-vis. and 1H and 13C-n.m.r) studies. The ligands behave as neutral bidentate components in the PdII and PtII complexes, whereas in RuIII, RhIII and IrIII complexes the ligands exist as neutral tridentates. Various ligand and nephelauxetic parameters have been calculated for the metal complexes. The RuIII, RhIII and IrIII complexes are six-coordinate distorted octahedral, whereas PdII and PtII are four coordinated. The ligands and their platinum group complexes exhibit a potent cytotoxic activity against Ehrlich ascites tumour cells in vitro but appear to be more in vivo.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018416624951
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  • 9
    Electronic Resource
    Electronic Resource
    Photoluminescence from oxidised Si nanoparticles produced by CW CO2 laser synthesis in a continuous-flow reactor (1997)
    Springer
    Journal of materials science 16 (1997), S. 221-223 
    Details
    ISSN: 1573-4811
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Abstracts are not published in this journal
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018551707263
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  • 10
    Electronic Resource
    Electronic Resource
    Palmitoylcarnitine, and important component of the repair system in the synaptosome membrane, in oxidative stress (1997)
    Springer
    Bulletin of experimental biology and medicine 123 (1997), S. 565-567 
    Details
    ISSN: 1573-8221
    Keywords: synaptosomes ; oxidative stress ; palmitoylcarnitine ; reacylation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Oxidative stress is accompanied by a considerable rise of palmitic acid incorporation into phosphatidylethanolamine of synaptosome membranes due to activation of lysophosphatidylethanolamine palmitoyltransferase and carnitine palmitoyltransferase. In the absence of ATP carnitine palmitoyltransferase plays an essential role in reacylation of phosphatidylethanolamine, and palmitoylcarnitine serves as a reserve pool of palmitoyl coenzyme A.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02458078
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