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  • 1
    Electronic Resource
    Electronic Resource
    Microstructural changes in a colloidal liquid in the shear thinning and shear thickening regimes (1999)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 111 (1999), S. 4827-4838 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The structure of a colloidal suspension under shear flow was studied by in situ small angle neutron scattering (SANS). This suspension exhibited shear thinning at low shear rates and shear thickening at high shear rates. Under quiescent conditions, the SANS profiles were azimuthally symmetric and contained a well-defined scattering maximum. This is due to local, liquidlike correlations between neighboring particles. Increasing shear rate lead to changes in the interparticle correlations. These changes are quantified by obtaining the anisotropic structure factor of the suspension under shear flow. We found an increased probability for the formation of inter-particle clusters in the gradient-vorticity plane. This results in an increase in the low angle scattering intensity in the flow direction, and the scattering peak, observed under quiescent conditions, is reduced to a shoulder. We found no evidence for a shear-induced phase transition in our experimental window. At low shear rates (γ(overdot)), the microstructure is relatively insensitive to shear rate. On the other hand, a pronounced shear rate dependence of microstructure is observed when γ(overdot)(approximate)1/τ, where τ is the characteristic time for the decay of concentration fluctuations. Dynamic light scattering was used to measure τ. The onset of shear thickening occurs when γ(overdot)τ is of order unity suggesting an intimate relationship between quiescent dynamics, and shear-induced microscopic and macroscopic changes. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.479245
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  • 2
    Electronic Resource
    Electronic Resource
    Dielectric properties of silicon nitride films deposited by microwave electron cyclotron resonance plasma chemical vapor deposition at low temperature (1997)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 71 (1997), S. 336-337 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The dielectric properties of amorphous silicon nitride (SiNx) films that were prepared by microwave electron cyclotron resonance plasma chemical vapor deposition at low temperature in the frequency range 5 Hz–1 MHz have been investigated. The dielectric dispersion in the frequency range exhibits two fractional power laws of (ε′−ε∞′)∝ω−p1 and (ε′−ε∞′)∝ωn1−1 with p1=0.12–0.18 and n1=0.95–0.96. These are close to the result predicted by the many-cluster anomalous conduction theory of fractal structure. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.119531
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  • 3
    Electronic Resource
    Electronic Resource
    Deposition of diamond-like carbon films by electrolysis of methanol solution (1996)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 69 (1996), S. 1074-1076 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: By electrolysis of the methanol solution, an attempt was made to deposit diamondlike carbon (DLC) films on silicon substrate at temperature of less than 60 °C. Substrates were negatively biased with a dc potential of 0 to −3000 V. IR spectra showed that the O–H, C–H, and C–O vibration bands of electrolyte decreased remarkably after electrolysis and a new peak characterized as the C=C bond appeared. The deposited films were characterized as DLC films by Raman spectroscopy. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.116935
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  • 4
    Electronic Resource
    Electronic Resource
    Fullerene formation during production of chemical vapor deposited diamond (1995)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 66 (1995), S. 430-432 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report a novel method for fullerene formation during diamond synthesis via a hot filament, chemical vapor deposition (CVD) procedure. The fullerenes occur in the soot that forms as a by-product on the edges and rear surface of the substrate holder, where the temperature does not favor diamond deposition. Mass spectrometry of the soot shows a peak having a mass to charge ratio corresponding to C60. From typical concentrations of gaseous species in the diamond-growing CVD chamber, we conclude that hydrocarbon species such as CH3 or C2H2 may be the precursors for the fullerene in the CVD chamber. The atomic hydrogen in the gaseous species is believed to play an important role in removing the hydrogen from hydrocarbon to form the all-carbon fullerene. Our observations also suggest that fullerenes produced in the CVD diamond growth chamber play a role in diamond nucleation on foreign substrates. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.114046
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  • 5
    Electronic Resource
    Electronic Resource
    En passant neurotrophic action of an intermediate axonal target in the developing mammalian CNS (1999)
    [s.l.] : Macmillian Magazines Ltd.
    Nature 401 (1999), S. 765-769 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] During development, neurons extend axons to their targets, then become dependent for their survival on trophic substances secreted by their target cells. Competition for limiting amounts of these substances is thought to account for much of the extensive naturally-occurring cell death that is seen ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/44521
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  • 6
    Electronic Resource
    Electronic Resource
    The influence of the p53 gene on the in vitro chemosensitivity of colorectal cancer cells (1999)
    Springer
    Journal of cancer research and clinical oncology 125 (1999), S. 357-360 
    Details
    ISSN: 1432-1335
    Keywords: Key words Colorectal neoplasms ; Apoptosis ; Chemosensitivity ; p53 gene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Purpose : The p53 gene is considered one of the most important in the control of apoptosis, and its mutations have a close relationship with chemosensitivity. The aim of this work was to investigate the role of p53 in the apoptosis of colorectal cancer cells in vitro, induced by 5-fluorouracil (5-FU) and hydroxy-camptothecin (HCPT). Methods : A total of 39 colorectal cancer samples from patients were treated in vitro with 5-FU (10 μg/ml), 5-FU (10 μg/ml) + leucovorin (5 μg/ml), HCPT (0.1 μg/ml) and HCPT (0.1 μg/ml) + Salvia mitorrhiza (6 μl), using an in situ terminal deoxynucleotidyltransferase assay to detect chemosensitivity. p53 gene mutations from tumor DNA were detected, after amplification by the polymerase chain reaction of exons 5–8, by non-radioactive single-strand conformation polymorphism. Results : p53 gene mutations were observed in 43.6% (17/39) of colorectal carcinomas, when the terminal deoxynucleotidyltransferase assay was used to detect the tumor apoptotic rate. Cells with mutated p53 had lower chemosensitivity than those without (p 〈 0.01). Conclusion : Routine assessment of p53 status may be helpful in selecting patients with the wild-type p53 gene, who have a predictably better response to chemotherapy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004320050286
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  • 7
    Electronic Resource
    Electronic Resource
    Approximate expressions of determining the double layer energy and force of interaction between two charged colloidal spheres (1995)
    Springer
    Colloid & polymer science 273 (1995), S. 947-950 
    Details
    ISSN: 1435-1536
    Keywords: Force ; energy ; sphere ; Derjaguin method
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The approximate expressions have been obtained to calculate the electrical double layer energy and force between two spherical colloidal particles based on the improved Derjaguin approximation. Results for identical spheres interacting under constant surface potential, constant surface charge are given. Comparison of present results with numerical results calculated by Carnie and Chan is made. The expressions are found to work quite well for the constant surface potential case, and for the constant charge case, we make correction for the expressions. The results given are satisfactory providedkh≧0.4.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00660372
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  • 8
    Electronic Resource
    Electronic Resource
    Relationship between interferon therapy and variability in nonstructural gene 5b of hepatitis C virus (1998)
    Springer
    Journal of gastroenterology 33 (1998), S. 684-693 
    Details
    ISSN: 1435-5922
    Keywords: Key words: hepatitis C virus ; nonstructural gene 5 ; quasispecies ; sequence analysis ; interferon
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract: The hepatitis C virus (HCV) quasispecies nature in the hypervariable region (HVR) has been reported and found to relate to the effectiveness of interferon (IFN) treatment. However, the quasispecies nature in the nonstructural (NS) 5b region remains to be addressed. To examine this characterization and relationship with IFN therapy, we sequenced six independent HCV clones from each of eight patients. The eight patients were classified as responders or nonresponders to IFN. In the four responders, we found one to three isolates in each of the six clones. In the nonresponders, the six clones consisted of four, five, six, and six isolates, respectively. Compared the (NS) 5b genes of the isolates obtained from the patients with that of the reported hepatitis C virus HC-C2 or HC-J6 isolate the ratio of nonsynonymous to total substitutions ranged from 17.61% to 30.95% in the responders and from 33.11% to 76.47% in the nonresponders. We also compared posttreatment with pretreatment sequences. The average number of varying amino acids ranged from 5.5 to 9.0 in isolates remaining after IFN treatment and from 4.3 to 5.5 in the isolates that disappeared with IFN treatment. Two changed amino acids (glycine to arginine and valine to isoleucine) (compared with the pretreatment clones) were found in the posttreatment clones of one of the responders and one amino acid change (valine to alanine) was found in another responder. These results suggest that the NS5b quasispecies correlates with IFN treatment effectiveness. These results also implied that the heterogeneity in different hierarchical strata has a common impact on IFN treatment, making infected patients resistant to IFN. Our study also provides evidence that HCV elimination and mutation may occur simultaneously during IFN therapy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s005350050156
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  • 9
    Electronic Resource
    Electronic Resource
    Genetic variability and characterization of non-structural region 5 of hepatitis C virus genome from Chinese patients (1998)
    Springer
    Journal of gastroenterology 33 (1998), S. 62-72 
    Details
    ISSN: 1435-5922
    Keywords: Key words: hepatitis C virus ; nonstructural region 5 ; sequence analysis ; China
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract: Sequence variation in the putative nonstructural region 5b (NS5b) of hepatitis C virus (HCV) was analyzed in China. Complementary DNA fragments from sera of 49 Chinese patients were amplified by polymerase chain reaction (PCR) and the products were cloned and sequenced. Based on the comparison in NS5b of 33 clones of genotype 1b and 16 clones of genotype 2a, Chinese isolates of HCV belong to the same subtype as HCV-J, and HC-J6 from Japan. There does exist, however, some heterogeneity in the primary structure of the nucleotide acid. Higher homology was found among Chinese isolates than among Chinese isolates and Japanese isolates. Furthermore, among Chinese isolates, we found some conserved nucleotide acid positions different from those of Japanese isolates. Comparison of average homology among the 33 clones of genotype 1b and the 16 clones of genotype 2a indicated that the average homology among genotype 2a was lower than that among genotype 1b. In addition, a deletion of three nucleotide acids and a frame-shift, resulting in the introduction of an in-frame stop codon, were first observed in the NS5b region. These results indicated geographical differences in the distribution of individual HCV isolates, and the existence of a local variant in the same subtype. Our findings also suggested the need for further study on the sequence of genotype 2a, to improve diagnosis and help to advance the development of a vaccine.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s005350050046
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  • 10
    Electronic Resource
    Electronic Resource
    Nonlinear rheology and flow-induced structure in a concentrated spherical silica suspension (1998)
    Springer
    Rheologica acta 37 (1998), S. 1-6 
    Details
    ISSN: 1435-1528
    Keywords: Key words Suspension ; small angle neutron ; scattering ; shear-thinning ; shear-thickening
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003970050085
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