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  • 1
    Electronic Resource
    Electronic Resource
    Theoretical studies of inclusion complexes of α- and β-cyclodextrin with benzoic acid and phenol (1997)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 65 (1997), S. 1135-1152 
    Details
    ISSN: 0020-7608
    Keywords: Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A series of semiempirical molecular orbital calculations using the AM1 method were performed on the inclusion complexes of α- and β-cyclodextrin with benzoic acid and phenol in the “head-first” and “tail-first” positions. The AM1 results show that α-cyclodextrin complexes with both guest compounds in the “head first” position are more stable than in the “tail-first” position, while the β-cyclodextrin complex with phenol in the “tail-first” position is more stable, but with benzoic acid, the “head-first” position is more stable. The driving forces for complex formation were investigated based on different intramolecular and intermolecular interactions. In addition, 1SCF AM1 calculations were performed on the β-cyclodextrin complexes with benzoic acid in the “tail-first” and “head-first” positions with the benzoic acid moved stepwise along the Z-axis of the β-cyclodextrin principal axis coordinate system.   © 1997 John Wiley & Sons, Inc. Int J Quant Chem 65: 1135-1152, 1997
    Additional Material: 3 Ill.
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  • 2
    Electronic Resource
    Electronic Resource
    Theoretical studies of inclusion complexes of β-cyclodextrin with methylated benzoic acids (1997)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 64 (1997), S. 711-719 
    Details
    ISSN: 0020-7608
    Keywords: Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: AM1 semiempirical molecular orbital calculations have been performed on the inclusion complexes of β-cyclodextrin (β-CD) with methylated benzoic acids in two orientations, the “head-first” and “tail-first” positions. In the former, the CO2H group points toward the primary hydroxyls of the CD. In the latter, it points away from them. Out of 30 possible inclusion complexes, AM1 results predict only three clearly stable inclusion complexes. These are β-CD with 4-methyl benzoic acid in the head-first position, β-CD with 2,4-dimethyl benzoic acid in the head-first position, and β-CD with 3,5-dimethyl benzoic acid in the tail-first position. The orientations of the stable inclusion complexes correlate with the total number of intramolecular hydrogen bonds and intermolecular hydrogen bonds. The stability of a complex also correlates with the closeness of the host and guest geometries in the complex to their isolated molecule geometries.   © 1997 John Wiley & Sons, Inc. Int J Quant Chem 64: 711-719, 1997
    Additional Material: 2 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    Structure and properties of NH52+: A dication with two 2-electron 3-center bonds (1998)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 70 (1998), S. 1003-1007 
    Details
    ISSN: 0020-7608
    Keywords: dications ; coupled-cluster calculations ; penta coordinate nitrogen ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The dication NH52+ has been studied by state-of-the-art quantum chemical techniques. NH52+ is a square-based pyramid with C4v symmetry. The apical H is bonded to N with a 2-electron covalent bond, while the other H atoms are bonded to N through degenerate 2-electron 3-center bonds. No other local minimum exists on the potential energy surface. A C2v transition state linking equivalent C4v structures is only 1.35 kcal mol-1 higher in energy. The barrier to deprotonation is 26.4 kcal mol-1.   © 1998 John Wiley & Sons, Inc. Int J Quant Chem 70: 1003-1007, 1998
    Additional Material: 1 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    On the determination and ramifications of chaos in many-body systems: A model study of polyethylene (1997)
    Weinheim : Wiley-Blackwell
    Macromolecular Theory and Simulations 6 (1997), S. 577-590 
    Details
    ISSN: 1022-1344
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Computational methods for elucidating information related to the dynamical behavior of multidimensional systems are presented and applied in the area of macromolecular dynamics. Results indicate that the dimensionality of chaotic dynamics for a model of polyethylene can only be characterized for a very narrow range of extremely low temperature (0-2 K). These results provide evidence that suggests the dynamics of this system are completely chaotic at temperatures as low as 10 K. The preponderance of increasing density of low frequency floppy vibrational modes in large molecular systems provides a facile mechanism for the onset of global chaos. Ramifications of such global chaos to the accurate modeling and simulation of macromolecular dynamics is discussed.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mats.1997.040060217
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  • 5
    Electronic Resource
    Electronic Resource
    Influence of formulation chemistry on the locus of failure of adhesive joints (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 23 (1995), S. 342-348 
    Details
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The durability of photocured resins adhered to ceramic substrates has been investigated. Monochromated XPS and time-of-flight SIMS were employed to determine the precise locus of failure in butt-joints comprised of a photocured resin adhered to either a 96% pure, debased alumina substrate or single-crystal silicon. Prolonged (〉 14 days) immersion in water at 50°C resulted in cohesive failure, with 1-2 nm of polymer remaining on one of the ceramic substrates. An absence in the spectrum of any components attributable to characteristic groups from a major constituent of the polymer within this overlayer suggested the possibility that one of the minor resin components was aggregating at the organic/inorganic interface to produce an in situ weak boundary layer. The interactions of some of the organic molecules present in the formulation with the α-alumina substrate were investigated using molecular modelling techniques to indicate the most favourable interactions with the substrate. Durability studies were also carried out on a reformulated photocured resin to investigate the effect of removal of the ethoxylated methacrylate monomer, suspected of being the principal organic component at the weak boundary layer, on both joint performance and locus of failure.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/sia.740230511
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  • 6
    Electronic Resource
    Electronic Resource
    The use of high-resolution XPS and ToF-SIMS to investigate segregation phenomena of minor components of a model coil coating formulation (1998)
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 26 (1998), S. 444-454 
    Details
    ISSN: 0142-2421
    Keywords: XPS ; ToF-SIMS ; surface segregation ; coil coatings ; adhesion ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The segregation of minor components - a melamine-formaldehyde resin and a poly(acrylic) flow control agent - in a model epoxy resin coil coating applied to hot-dipped galvanized steel has been investigated by high-resolution XPS and time-of-flight SIMS (ToF-SIMS). It is shown that by using the highest resolution monochromated XPS currently available, the C 1s spectrum can be peak fitted to account for all eleven carbon functionalities present in the three components of the organic coating. A ToF-SIMS analysis of the melamine-formaldehyde resin has been undertaken and a comprehensive ion fragmentation scheme for the positive ion spectrum of this molecule in the range 0-500 Da is proposed. It is shown, by both surface analytical techniques, that when the flow control agent is excluded from the formulation the surface of the paint film is enriched in the melamine-formaldehyde component. On addition of the flow control agent such segregation is only identified by XPS; the ToF-SIMS spectrum resembles that of the flow control agent. This is taken to be an indication of monolayer segregation of this component at the paint/air interface. Such segregation phenomena are shown to be insensitive to substrate surface pretreatment. © 1998 John Wiley & Sons, Ltd.
    Additional Material: 9 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    Peptides as standards for denaturing isoelectric focusing (1995)
    Weinheim : Wiley-Blackwell
    Electrophoresis 16 (1995), S. 22-27 
    Details
    ISSN: 0173-0835
    Keywords: Standards ; Peptides ; Isoelectric focusing ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: A set of commercially available peptides suitable for use as standards in denaturing isoelectric focusing (IEF) is described. The peptides N-procalcitonin fragment 1-57 (pI 3.98), Gln11-amyloid β-protein fragment 1-28 (pI 5.76), gastric inhibitory polypeptide (pI 7.14), parathyroid hormone fragment 1-34 (pI 8.64) and human β-endorphin (pI 9.49) can be focused to their isoelectric point in the presence of 8 M urea and 2% Nonidet P-40, and subsequently fixed and stained in polyacrylamide gels. The peptides give a linear standard curve in close agreement with a slope determined with a surface pH electrode. Under the same conditions some proteins focus to positions significantly at odds with their theoretical isoelectric point. The origins of these discrepancies and the implications for the determination of isoelectric points of unknown proteins by denaturing IEF are discussed.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.1150160106
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  • 8
    Electronic Resource
    Electronic Resource
    Separation of tumor necrosis factor α isoforms by two-dimensional polyacrylamide gel electrophoresis (1997)
    Weinheim : Wiley-Blackwell
    Electrophoresis 18 (1997), S. 1086-1091 
    Details
    ISSN: 0173-0835
    Keywords: Immobilized pH gradients ; Two-dimensional polyacrylamide gel electrophoresis ; Tumor necrosis factor α ; Glycosylated isoform ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: The mouse macrophage cell-line RAW264.7, stimulated with lipopolysaccharide, was used as a model for the study of the production of tumor necrosis factor (TNF) isoforms. TNF is synthesised initially as a 26 kDa transmembrane precursor, which is then processed enzymatically by a protease to release a mature molecule of 17 kDa. Dose-dependent production of transmembrane TNF was assessed by fractionation of cell membranes and Western blot analysis followed by autoradiography and densitometry. Isoforms of both the precursor and mature molecules were separated using two-dimensional (2-D) electrophoresis with immobilised pH gradient 3-10 linear gels as the first dimension. After radiolabelling of cells with 35S, both cell-associated and supernate-associated TNF isoforms were immunoprecipitated. A large number of protein spots were visualised on the 2-D gel map, for both the transmembrane and mature TNF species, more than have been detected previously using one-dimensional sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). The likelihood that these putative isoforms were the result of differential glycosylation was tested by preincubating the cells with tunicamycin. This had the effect of reducing the number of protein spots, notably the higher molecular weight species. There were a number of precursor TNF isoforms that were unchanged upon tunicamycin treatment and these presumably reflect protein modifications other than glycosylation.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.1150180710
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  • 9
    Electronic Resource
    Electronic Resource
    Electrophoresis combined with novel mass spectrometry techniques: Powerful tools for the analysis of proteins and proteomes (1998)
    Weinheim : Wiley-Blackwell
    Electrophoresis 19 (1998), S. 1811-1818 
    Details
    ISSN: 0173-0835
    Keywords: Electrospray ionization ; Mass spectrometry ; Capillary electrophoresis ; Two-dimensional gel electrophoresis ; Proteome ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Analytical and preparative electrophoresis separation techniques have been essential tools in protein biochemistry and the biological sciences in general. The combination of high resolution electrophoresis techniques with high performance analytical procedures has dramatically enhanced analytical protein biochemistry. In this report we describe the combination of electrophoretic separation techniques with electrospray ionization (ESI) tandem mass spectrometry (MS/MS). A series of different techniques, consisting of automated high performance liquid chromatography (HPLC)-MS/MS, capillary-HPLC-MS/MS, and solid phase extraction (SPE)-capillary zone electrophoresis (CZE)-MS/MS, are described in the context of the identification of high pmol to the low fmol amounts of proteins. Application of these powerful new tools for the analysis of proteins on a large proteome-wide scale is presented. Furthermore, the combination of orthogonal separation techniques, such as immobilized metal affinity chromatography (IMAC) with SPE-CZE-MS/MS, and IMAC followed by HPLC, and by SPE-CZE-MS/MS, are presented for the detailed investigation of post-translational modifications of specific proteins.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.1150191045
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