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  • 1
    Electronic Resource
    Electronic Resource
    Kinetics of polyesterification III: Solid-state polymerization of polyethylene terephthalate (1987)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 25 (1987), S. 533-549 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Experimental studies on the solid-state polymerization (SSP) of polyethylene terephthalate (PET) for the particle sizes of 14-16 mesh at 170-200°C and for the particle sizes of 14-18 mesh at 210-240°C are carried out under a vacuum of about 60 mtorr. Analysis of the data of the concentrations of hydroxyl and carboxyl groups and the number average molecular weight during the SSP allows determinations of the rates of esterification and ester interchange separately. It is found that at the temperature 170-200°C and the particle size 80-100 mesh the SSP is end-group diffusion limiting, and that at the temperature 210-240°C and the particle size 14-16 mesh the ester interchange is ethylene glycol diffusion limiting and the esterification is predominantely end-group diffusion limiting due to higher diffusion rate of water. These phenomena are explored by an assistance of the proposed rate expressions for the end-group diffusion limited reactions and diffusion models for the by-products, water, and ethylene glycol.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1987.080250208
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  • 2
    Electronic Resource
    Electronic Resource
    The performance of immobilized glucose isomerase supported by shrimp chitin in various types of reactors (1983)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 25 (1983), S. 725-733 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Five different types of reactors were employed for glucose isomerization using shrimp shell as the support on which to immobilize the glucose isomerase. The Michaelis-Menten constants and effective diffusivity of glucose in the immobilized enzyme bed were experimentally determined and used in a theoretical analysis of the radial-flow reactor. The fractional conversions of the radial-flow, fluidizedbed, and packed-bed reactors with the same -residence time were found experimentally to be almost the same. This result reveals that the use of radial-flow and fluidized-bed reactors for this immobilized enzyme system is highly feasible.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260250309
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  • 3
    Electronic Resource
    Electronic Resource
    Conformational aspect of polypeptide structure. XLIV. Conformational transitions of poly(N-methyl-alanines) induced by trifluoroacetic acid (1973)
    New York : Wiley-Blackwell
    Biopolymers 12 (1973), S. 2549-2561 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of poly(N-methyl-L-alanine) and poly (N-methyl-DL-alanine) are described. The polymers were examined by 220 MHz high-resolution nuclear magnetic resonance (nmr) and circular dichroism (CD). The results demonstrate that poly(N-methyl-L-alanine) exists as an ordered helical structure with all the amide bonds in the trans configuration in appropriate solvents. As trifluoroacetic acid (TFA) is added to the solutions of the polymer in helix-supporting solvents, resonances corresponding to both trans and cis amide conformations of N-methyl, C-methyl, and α-CH are observed. The presence of both the trans and the cis peptide bonds in a polymer chain disrupts the ordered structures. Our conclusions from CD data are in agreement with the nmr results. Ultracentrifugation shows that degradation of the polymer chain does not occur during the TFA treatment.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1973.360121109
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  • 4
    Electronic Resource
    Electronic Resource
    Viscoelastic properties of dilute nematic mixtures containing cyclic and hyperbranched liquid crystal polymers dissolved in a nematic solvent (1995)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 33 (1995), S. 1213-1223 
    Details
    ISSN: 0887-6266
    Keywords: viscoelastic properties ; dynamic light scattering ; dilute nematic solutions ; cyclic liquid crystal polymer ; hyperbranched liquid crystal polymer ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The twist and bend viscosities of dilute solutions of cyclic and hyperbranched liquid crystal polymers (LCP) dissolved in low molar mass nematic solvents were determined via dynamic light scattering analysis. These results were compared to those of linear chains with similar chemical repeat structures. The nematic solvent used was 4′-pentyloxy-4-cyanobiphenyl (50CB). The cyclic LCP oligomers, Cy TPB10, have a mesogenic group, 1-(4-hydroxy-4′-biphenyl)-2-(4-hydroxyphenyl) butane, separated by flexible decamethylene spacers. The twist viscosity of the cyclic Cy-TPB10 oligomers increases with molecular weight more strongly than the linear, TPB-10, suggesting that the hydrodynamic behavior of Cy-TPB10 is closer to that of a rigid rod than TPB10. Surprisingly, the intrinsic bend viscosity [ηbend] of Cy-TPB10 decreases with molecular weight, in contrast to the positive dependence for linear TPB10. This may reflect the higher strain energy in the smaller ring sizes. The hyperbranched LCP, TPD-b-8, is also based on the mesogen 10-bromo-1-(4-hydroxy-4′-biphenyl)-2(4-hydroxyphenyl) decane but with octyl groups at the chain ends. We compare the viscoelastic behavior of dilute nematic solutions of TPD-b-8 in 50CB against that of a linear main-chain LCP, TPB7, with the same mesogenic group but with heptamethylene spacers. The viscometric properties of TPD-b-8/50CB and TPB7/50CB are quite different. The results suggest that each chain is prolate (i. e., R∥ 〉 R⊥) but that TPD-b-8 has a smaller chain anisotropy than that of TPB7. © 1995 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1995.090330807
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  • 5
    Electronic Resource
    Electronic Resource
    Acid-catalyzed reductive amination of aldoses with 8-aminopyrene-1,3,6-trisulfonate (1996)
    Weinheim : Wiley-Blackwell
    Electrophoresis 17 (1996), S. 347-351 
    Details
    ISSN: 0173-0835
    Keywords: Aldoses ; Reductive amination ; Acid catalysis ; Capillary electrophoresis ; Laser-induced fluorescence ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: The reductive amination of monosaccharides with 8-aminopyrene-1,3,6-trisulfonate (APTS) in seven different organic acids including the commonly used acetic acid was investigated by capillary electrophoresis (CE) with laser-induced fluorescence (LIF) detection. The correlation between the yields of the saccharide-APTS adducts and pKa of the organic acid catalyst is consistent with general acid catalysis of the rate-determining step of the reductive amination reaction. Derivatization in the presence of organic acids of higher strength than acetic acid produced substantially higher yields of APTS-sugar adducts, an effect which is more pronounced for N-acetylamino sugars. Optimum yields were obtained using citric acid as a catalyst. Conversion of a few nanomoles of neutral saccharides to the APTS derivatives is achieved at 75°C in less than 60 min.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.1150170210
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  • 6
    Electronic Resource
    Electronic Resource
    Characterization of proteins by capillary electrophoresis in fused-silica columns: Review on serum protein analysis and application to immunoassays (1994)
    Weinheim : Wiley-Blackwell
    Electrophoresis 15 (1994), S. 13-21 
    Details
    ISSN: 0173-0835
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Protein mixtures can be characterized in terms of their separations by capillary electrophoresis (CE). The separation of proteins by CE is performed in untreated fused-silica columns. Model proteins and complex protein mixtures with pI values ranging from 4.0 to 11.0 are separated in such columns in less than 10 min in the presence of phosphate buffer with a pH between 4.0 and 9.0. The application of CE separation procedures for routine analysis of protein in serum, urine, and cerebrospinal fluid in borate-based buffer is also demonstrated. The detection of protein in CE is usually based on the intrinsic ultraviolet (UV) absorbance of the peptide bond at or near 200 nm, which provides a detection limit of about 10-5 M. The same protein separation procedures can also be applied to immunochemical reaction systems in which one component is labeled. Thus, an antigen analyte, or the antibody to the analyte, may be labeled with a fluor and detected by laser-induced fluorescence (LIF). With a fluorescent-labeled reactant, the use of LIF detection further extends the detection limit to 10-11 M. The CE separation technique for proteins provides a means to separate the bound and free species of the labeled antigen or antibody without the use of a solid support. The application of these separation techniques in conjunction with laser-induced fluorescence detection to make possible the homogeneous immunochemical measurement of species at concentrations in the range of 10-9 to 10-10 M is shown.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.1150150104
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  • 7
    Electronic Resource
    Electronic Resource
    Separation of 1-aminopyrene-3,6,8-trisulfonate-labeled asparagine-linked fetuin glycans by capillary gel electrophoresis (1996)
    Weinheim : Wiley-Blackwell
    Electrophoresis 17 (1996), S. 412-417 
    Details
    ISSN: 0173-0835
    Keywords: Capillary gel electrophoresis ; Fetuin ; Sialylated oligosaccharides ; Laser-induced fluorescence detection ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Asparagine-linked glycans of bovine fetuin were separated by capillary gel electrophoresis after enzymatic release (peptide-N-glycosidase F) and labeling via reductive amination by a fluorescent dye, 1-aminopyrene-3,6-8-trisulfonate (APTS). At low separation pH (2.5) only two dominant peaks were observed. Increasing the separation buffer pH to 4.75 resulted in complete separation of two primary doublets and several minor peaks from the fetuin N-linked glycan pool. Two of the four major peaks were spiked with purified individual standards and were identified as trisialylated triantennary structures with different sialylation linkages. The other two larger peaks were postulated to be tetrasialylated triantennary structures, based on calculations considering their corresponding glucose unit (GU) values. Effects of the electrophoretic separation parameters, such as gel concentration, electric field strength and temperature on the migration behavior of the two major doublets of the fetuin glycan pool were also thoroughly examined. Our data suggest that the capillary gel electrophoresis separation of the multisialylated branched oligosaccharides with different linkage isomers, released from bovine fetuin, is fundamentally based on their degree of sialylation and hydrodynamic volumes.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.1150170221
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  • 8
    Electronic Resource
    Electronic Resource
    Profiling glycoprotein N-linked oligosaccharide by capillary electrophoresis (1998)
    Weinheim : Wiley-Blackwell
    Electrophoresis 19 (1998), S. 2639-2644 
    Details
    ISSN: 0173-0835
    Keywords: Erythropoietin ; Fetuin ; Kallikrein ; Ribonuclease B ; 8-Amino-1,3,6-trisulfonic acid ; Sialidase ; Capillary electrophoresis ; Laser-induced fluoresence detection ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: A method for analysis of N-linked oligosaccharides derived from glycoproteins including sialic acid-containing species is presented. It is based on the combination of specific chemical and enzymatic conversions coupled with capillary electrophoretic (CE) separation and laser-induced fluorescence (LIF) detection. Glycoproteins were heat-denatured in the presence of a reducing agent and the N-linked oligosaccharides were released by peptide N-glycosidase (PNGase F; EC3.5.1.52)-catalyzed hydrolysis. The released N-linked oligosaccharides were derivatized with 8-aminopyrene-1,3,6-trisulfonate (APTS) under mild reductive amination conditions in which desialylation and loss of fucose residues are minimized. A model N-linked oligosaccharide, desialylated, galactosylated biantennary, core-substituted with fucose (A2F) was tested for APTS-based derivatization chemistry with excellent recovery of the adduct without losing fucose and neuraminic acid residues. The profiles of heavily sialylated N-linked oligosaccharides derived from fetuin, recombinant human erythropoietin and kallikrein are reported and the data show that the present method produces a high resoluton of the N-linked oligosaccharide profile for fingerprinting glycans derived from glycoproteins.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.1150191512
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