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1

Digitale Medien

Transmission electron microscopy study of defects in Sn-doped GaAs films grown by molecular beam epitaxy (1987)

Chen, S. H. ; Carter, C. B. ; Enquist, P.

Springer

Applied physics 44 (1987), S. 143-151

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ISSN: 1432-0630

Schlagwort(e): 68.55Jh ; 81.30Fb ; 68.35

Quelle: Springer Online Journal Archives 1860-2000

Thema: Maschinenbau , Physik

Notizen: Abstract Films of GaAs, heavily doped with Sn, which have been grown by molecular-beam epitaxy are found to contain single-crystal Sn particles situated in the nearsurface region of the epilayer GaAs. The morphology and chemical composition of the particles have been examined by using cross-section transmission electron microscopy combined with energy-dispersive x-ray spectroscopy. Different growth conditions were used to study the Sn-particle formation and high-resolution transmission electron microscopy was used to investigate microstructures. The observations are discussed in terms of several models previously proposed for these phenomena.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF00626415

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2

Digitale Medien

DNA polymorphisms in north Sardinian newborns and their linkage with abnormal γ globin gene arrangements and with βo-thalassemia (1986)

Hattori, Y. ; Kutlar, F. ; Chen, S. S. ; [weitere]

Springer

Biochemical genetics 24 (1986), S. 669-681

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ISSN: 1573-4927

Schlagwort(e): fetal hemoglobin ; βo-thalassemia ; γ globin gene triplication ; γ globin gene deletion ; haplotypes ; silent β-chain variant ; F-Sardinia ; the AγT chain ; —Gγ—Gγ— and —Aγ—Aγ— arrangements

Quelle: Springer Online Journal Archives 1860-2000

Thema: Biologie , Chemie und Pharmazie

Notizen: Abstract Fetal hemoglobin analysis and globin gene mapping have identified one type of βo-thalassemia and four different γ globin gene arrangements among newborn babies from the northern part of Sardinia. The βo-thalassemia with a nonsense mutation at codon 39 was found on two chromosomes, each with a distinct pattern of polymorphic restriction sites; one had the AγT (Aγ75 Ile → Thr) mutation, while the second did not. Four closely related haplotypes were identified for chromosomes with the AγT mutation. The γ-thalassemia heterozygosity with the —GAγ— hybrid gene fell into two categories. One apparently originated through crossing-over between mismatched chromosomes characterized by the most common haplotype, while the other had polymorphisms resembling those of a less frequently occurring chromosome. Chromosomes with the —Gγ—AGγ—Aγ— triplication had polymorphic sites to be expected for this condition, being complimentary to the —GAγ— thalassemias. Of the two additional γ globin gene variations the —Gγ—Gγ— arrangement was associated with the chromosome with the most commonly occurring haplotype, while the chromosome with the —Aγ—Aγ— arrangement had a haplotype characteristic for that with the AγT mutation, which identified an —Aγ—AγT— arrangement. The incidental discovery of a silent β-chain mutant, Hb Hamilton, with the Val → Ile substitution at position β11, in five newborns was also reported.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF00499001

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3

Digitale Medien

SANS studies of concentrated protein solutions. I. Bovine serum albumin (1986)

Nossal, R. ; Glinka, C. J. ; Chen, S.-H.

New York : Wiley-Blackwell

Biopolymers 25 (1986), S. 1157-1175

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ISSN: 0006-3525

Schlagwort(e): Chemistry ; Polymer and Materials Science

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie

Notizen: Small-angle neutron scattering (SANS) was used to examine concentrated bovine serum albumin solutions of up to 20% protein w/v. At higher protein concentrations, scattering data show distinct features that can be ascribed to strong intermolecular interactions. Differential scattering cross-sections are fitted to a theoretical model of interparticle potential consisting of a hard core plus an exponentially decaying “tail.” For moderate ionic strength (0.03M K Acetate, pH 5.9), the intermolecular interaction agrees with the double-layer repulsive part of the well-known DLVO (Derjaguin, Landau, Verwey, Overbeek) theory for interacting colloidal particles. We thus demonstrate that it is possible to determine size parameters and the surface charge of protein molecules in dense solutions. At high salt concentrations (≥0.2M NaCl) data can be fitted by the same potential model, although interpretation in terms of DLVO theory is not possible. Even in this case, however, “effective” molecular size and potential parameters can be determined.

Zusätzliches Material: 7 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/bip.360250613

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4

Digitale Medien

Translational diffusion of polystyrene in 1,4-dioxane at infinite dilution determined with the extended Taylor dispersion method (1986)

Barooah, A. ; Sun, C. K. J. ; Chen, S. H.

Bognor Regis [u.a.] : Wiley-Blackwell

Journal of Polymer Science Part B: Polymer Physics 24 (1986), S. 817-825

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ISSN: 0887-6266

Schlagwort(e): Chemistry ; Polymer and Materials Science

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie , Physik

Notizen: The extended Taylor dispersion method was used to determine the translational diffusion coefficients of a series of polystyrene standards in 1,4-dioxane at infinite dilution at temperatures from 323.2 to 378.2 K. The experimental data suggest that in the context of Kirkwood's theory the Monte Carlo chain represents real polystyrene molecules better than does the Guassian chain with physically reasonable values for the hydrodynamic interaction parameter h*. The feasibility and accuracy of the simultaneous determination of the diffusivities of several polystyrene standards from a single dispersion measurement were also analyzed using a binary mixture of polystyrenes with molecular weights of 2000 and 100,000 as an example.

Zusätzliches Material: 3 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/polb.1986.090240408

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5

Digitale Medien

Translational diffusion of relatively short polystyrene chains in cyclohexane. II. An interpretation of hydrodynamic radius with the freely jointed chain model (1987)

Sun, C. K. Jacob ; Maa, Y. F. ; Chen, S. H.

Bognor Regis [u.a.] : Wiley-Blackwell

Journal of Polymer Science Part B: Polymer Physics 25 (1987), S. 1473-1480

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ISSN: 0887-6266

Schlagwort(e): Chemistry ; Polymer and Materials Science

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie , Physik

Notizen: The translational diffusion coefficients for three relatively short, nearly monodisperse polystyrene chains (with molecular weights 2000, 4000, and 9000) in liquid cyclohexane have been measured up to 523.2 K using the extended Taylor dispersion method. The resultant hydrodynamic radii are successfully interpreted with the freely jointed chain model corrected for the approximations intrinsic to Kirkwood's theory with Stokes' radius as the only adjustable parameter, which is found to decrease with chain length but approach a constant value for long enough chains. The experimentally observed hydrodynamic radii of polystyrene standards with molecular weights 17,500, 50,000 and 100,000 at 308.2 K conform quite well to the values predicted with the approach formulated in this work.

Zusätzliches Material: 2 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/polb.1987.090250709

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6

Digitale Medien

Diffusion and solubility of some azo dyes in swollen gelatin matrices: The effects of dye size, matrix swell, and dye-matrix interactions (1985)

Chen, S. P. ; Osterhoudt, H. W.

New York, NY [u.a.] : Wiley-Blackwell

Journal of Applied Polymer Science 30 (1985), S. 2075-2094

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ISSN: 0021-8995

Schlagwort(e): Chemistry ; Polymer and Materials Science

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie , Maschinenbau , Physik

Notizen: The diffusion coefficient (D) and the solubility coefficient (K) of three sulfonated azo dyes were measured in swollen gelatin membranes at pH 12 by two techniques (time lag and desorption rate), with good agreement between the two. A strong correlation was established between log D and the reciprocal of the free volume of the matrix. Hence, as free volume of the matrix increased (due to increasing solvent imbibition), dye mobility increased. As dye size increased, however, mobility decreased. Dye affinity for gelatin, as measured in dilute solutions by dynamic dialysis, was small and could be related to the dye solubility in more concentrated gelatin matrices. Increasing ionic strength or decreasing alcohol content increased K without affecting the dye mobility. On the other hand, the presence of polymers with strong affinity for the dye anions, e.g., polyvinylpyrrolidone, immobilized a large fraction of the dye ions and greatly slowed the overall dye transport.

Zusätzliches Material: 14 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/app.1985.070300524

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7

Digitale Medien

Translational diffusion of polystyrene in cyclohexane at infinite dilution from 283 to 348 K (1985)

Barooah, A. ; Chen, S. H.

New York : Wiley-Blackwell

Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 2457-2468

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ISSN: 0098-1273

Schlagwort(e): Physics ; Polymer and Materials Science

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie , Physik

Notizen: The translational diffusion coefficients are reported for polystyrenes with molecular weights 2000, 4000, and 9000 in cyclohexane at infinite dilution from 283.2 to 348.2 K. The results suggest that the hydrodynamic radii stay constant to within ±3% and that the real chain for molecular weight 9000 at 308.2 K is well represented by a Gaussian or Monte Carlo model involving the idea of statistical steps. Furthermore, the success of Hildebrand's free-volume empiricism has led to a correlation between Dμ0/T and M which represents the observed diffusivities to within ±2%.

Zusätzliches Material: 6 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/pol.1985.180231204

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