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  • 1
    Electronic Resource
    Electronic Resource
    Study of initial- and transition-state solvation in the solvolysis of tert-butyl halides in alcohols from infinite dilution activity coefficients (1993)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 6 (1993), S. 133-138 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The Gibbs energies of activation of the solvolytic reactions of tert-butyl halides (chloride, bromide and iodide) in eight mono-alcohols and eight di-alcohols were dissected into contributions from the initial state and transition state. The unified approach proposed by Abraham was applied and the various factors making up the overall solvent effect in both states were identified and compared. To perform this study, the Gibbs energies of transfer of the initial state were calculated using the infinite dilution activity coefficient values of the solutes in the solvents, γ∞. These values were determined from the UNIFAC group-contribution method, with the modified Flory-Huggins equation in the combinatorial term and with group interaction parameters from the Parameter Table exclusively based on experimental γ∞ data reported in the literature. It is concluded that solvent polarizability and polarity-HBD acidity and cavity effects during the activated process are mainly due to transition-state contributions.
    Additional Material: 5 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610060302
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  • 2
    Electronic Resource
    Electronic Resource
    Study of initial state and transition state solvation in the Menschutkin reaction of triethylamine with ethyl iodide in alcohols from infinite dilution activity coefficients (1993)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 6 (1993), S. 595-599 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The Gibbs energies of activation of the Menschutkin reactions of trethylamine with ethyl iodide in 10 monoalcohols and nine dialcohols, were dissected into contributions from the initial state and transition state. To perform this study, the infinite dilution activity coefficient values of the solutes in the solvents, γ∞, were determined by the UNIFAC group-contribution method, using the modified Flory-Huggins equation in the combinatorial term. For triethylamine, the γ∞ values were calculated using group-interaction parameters from the VLE Parameter Table, due to the nonavailability of specific γ∞ UNIFAC interaction parameters for the relevant groups. For ethyl iodide, the γ∞ values were calculated using the group-interaction parameters from the specific γ∞ UNIFAC Parameter Table, except for the solvents diethylene glycol and triethlene glycol, where VLE parameters were used for the same reasons as explained above for the triethylamine. The results were compared with those obtained for the unimolecular decomposition of tert-butyl halides. For the Menschutkin reaction, we conclude that solvent disruption and reorganization to a state appropriate to solvating the molecular species is a dominant interaction mechanisim.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610061011
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  • 3
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    Relation of phenotype evolution of HIV-1 to envelope V2 configuration (1993)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1993-06-04
    Description: Biological variability of human immunodeficiency virus type-1 (HIV-1) is involved in the pathogenesis of acquired immunodeficiency syndrome (AIDS). Syncytium-inducing (SI) HIV-1 variants emerge in 50 percent of infected individuals during infection, preceding accelerated CD4+ T cell loss and rapid progression to AIDS. The V1 to V2 and V3 region of the viral envelope glycoprotein gp120 contained the major determinants of SI capacity. The configuration of a hypervariable locus in the V2 domain appeared to be predictive for non-SI to SI phenotype conversion. Early prediction of HIV-1 phenotype evolution may be useful for clinical monitoring and treatment of asymptomatic infection.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Groenink, M -- Fouchier, R A -- Broersen, S -- Baker, C H -- Koot, M -- van't Wout, A B -- Huisman, H G -- Miedema, F -- Tersmette, M -- Schuitemaker, H -- New York, N.Y. -- Science. 1993 Jun 4;260(5113):1513-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Clinical Viro-Immunology, Central Laboratory of the Netherlands Red Cross Blood Transfusion Service, Amsterdam.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/8502996" target="_blank"〉PubMed〈/a〉
    Keywords: Acquired Immunodeficiency Syndrome/microbiology ; Amino Acid Sequence ; Base Sequence ; Biological Evolution ; Consensus Sequence ; Genetic Variation ; Giant Cells/microbiology ; HIV Envelope Protein gp120/*chemistry ; HIV Seropositivity/microbiology ; HIV-1/*chemistry/*genetics/pathogenicity ; Humans ; Male ; Molecular Sequence Data ; Phenotype ; Protein Conformation ; Recombination, Genetic
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 4
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    CD40 ligand gene defects responsible for X-linked hyper-IgM syndrome (1993)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1993-02-12
    Description: The ligand for CD40 (CD40L) is a membrane glycoprotein on activated T cells that induces B cell proliferation and immunoglobulin secretion. Abnormalities in the CD40L gene were associated with an X-linked immunodeficiency in humans [hyper-IgM (immunoglobulin M) syndrome]. This disease is characterized by elevated concentrations of serum IgM and decreased amounts of all other isotypes. CD40L complementary DNAs from three of four patients with this syndrome contained distinct point mutations. Recombinant expression of two of the mutant CD40L complementary DNAs resulted in proteins incapable of binding to CD40 and unable to induce proliferation or IgE secretion from normal B cells. Activated T cells from the four affected patients failed to express wild-type CD40L, although their B cells responded normally to wild-type CD40L. Thus, these CD40L defects lead to a T cell abnormality that results in the failure of patient B cells to undergo immunoglobulin class switching.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Allen, R C -- Armitage, R J -- Conley, M E -- Rosenblatt, H -- Jenkins, N A -- Copeland, N G -- Bedell, M A -- Edelhoff, S -- Disteche, C M -- Simoneaux, D K -- A125129/PHS HHS/ -- N01-CO-74101/CO/NCI NIH HHS/ -- New York, N.Y. -- Science. 1993 Feb 12;259(5097):990-3.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Howard Hughes Medical Institute, Baylor College of Medicine, Houston, TX 77030.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7679801" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Antigens, CD/*metabolism ; Antigens, CD40 ; Antigens, Differentiation, B-Lymphocyte/*metabolism ; Base Sequence ; CD40 Ligand ; DNA/chemistry/genetics ; Humans ; Immunoglobulin M/*blood ; Immunologic Deficiency Syndromes/*genetics/immunology ; Ligands ; Male ; Membrane Glycoproteins/*genetics ; Mice ; Molecular Sequence Data ; *Point Mutation ; Polymerase Chain Reaction ; T-Lymphocytes/*immunology ; Transfection ; *X Chromosome
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 5
    Electronic Resource
    Electronic Resource
    Microwave activation of the mutarotation of α-D-glucose: An example of an interinsic microwave effect (1993)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 6 (1993), S. 407-411 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The mutarotation reaction of α-D-glucose in ethanol-water solvent in a modified commercial microwave oven, when compared with control reactions carried out at identical temperatures, shows a non-thermal microwave effect, evidenced both by a more rapid reaction and by a change in relative amounts of α- and β-D-glucose over time.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610060705
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  • 6
    Electronic Resource
    Electronic Resource
    Oxidation kinetics of p-aminodiphenylamine with peroxydisulphate (1993)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 6 (1993), S. 609-614 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The kinetics of oxidation of p-aminodiphenylamine with the peroxydisulphate ion were investigated spectrophotometrically. The oxidation was accompanied by the appearance of a wine-red colour, which changed to become colourless. The reaction rate was measured by the stopped-flow technique with a UV spectrophotometer. The reactions proceeded with second-order kinetics, first-order for each individual reactant. Cationic micelles (cetyltrimethyl ammonium bromide) caused an enhancement in the reaction rate followed by inhibition at higher concentrations. Anionic micelles (sodium dodecyl sulphate), on the other hand, had a slightly retarding effect. The effects of radical scavenger, pH and ionic strength on the fast oxidation rate were examined. A mechanism consistent with the observations is discussed.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610061103
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  • 7
    Electronic Resource
    Electronic Resource
    Pharmacokinetics of the enantiomers of verapamil in the dog (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 5 (1993), S. 436-442 
    Details
    ISSN: 0899-0042
    Keywords: verapamil ; enantiomers ; kinetics ; blood binding ; dogs ; HPLC separation ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The intravenous (0.5 mg/kg) and oral (5 mg/kg) dose kinetics of verapamil were studied in 6 dogs during steady-state oral verapamil dosing (5 mg/kg every 8 h for 3 days). Racemic verapamil and norverapamil, a metabolite of verapamil, were quantitated in plasma by HPLC-fluorescence detection. The verapamil peaks eluting off the column were collected and rechromatographed on an Ultron-OVM column, which resolved the two verapamil enantiomers. After intravenous administration, the systemic clearance and apparent volume of distribution of (-)-(S)-verapamil were nearly twice that of the (+)-(R)-isomer. There was no difference in the elimination half-lives between the two isomers. After oral administration, the oral clearance of (-)-(S)-verapamil was 20 times that of the (+)-(R)-isomer. The apparent bioavailability of (+)-(R)-verapamil was over 14 times that of (-)-(S)-verapamil. The plasma protein binding of the (+)-(R)-isomer was slightly higher by 5% than (-)-(S)-verapamil; however, this effect was not enough to account for the difference between the apparent volume of distribution of the enantiomers, indicating that the tissue binding of (-)-(S)-verapamil was greater than that of the (+)-(R)-isomer. This data on the disposition of the enantiomers of verapamil in the dog is similar to that reported for man and demonstrates that the dog may be an appropriate animal model for man in future studies on the disposition of the enantiomers of verapamil. © 1993 Wiley-Liss, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530050608
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  • 8
    Electronic Resource
    Electronic Resource
    Acidities of 4-substituted benzoic, bicyclo[2.2.2]oct-1-yl and bicyclo[2.2.2]oct-2-enyl carboxylic acids (1993)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 6 (1993), S. 685-689 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Experimental gas-phase acidities are reported for a series of 4-substituted bicyclo [2.2.2] oct-1-yl carboxylic acids and for a limited number of the corresponding bicyclo [2.2.2] oct-2-enyl carboxylic acids. Similar acidities are also reported for additional 4-substituted benzoic acids, allowing a comparison of field and resonance effects between the three series. Ab initio molecular orbital calculations for these series of acids confirm the conclusion that the aromatic acids display direct field and resonance effects, whereas the acidities in the aliphatic series acids are largely determined by direct field effects.
    Additional Material: 5 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610061205
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  • 9
    Electronic Resource
    Electronic Resource
    Acidity constants of benzamide and some Ortho-substituted derivatives (1993)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 6 (1993), S. 101-106 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Acidity constants of benzamide and seven ortho-substituted derivatives were determined. Except for o-nitrobenzamide, all the amides exhibit medium effects. The data were treated by vector analysis. o-Aminobenzamide displays two protonation equilibria. The second acidity constant was determined by vector analysis and by the excess acidity function, since the acid strength provided by perchloric acid is insufficient for complete protonation. Different acidity functions and the ortho substituent effect on ionization of the amide group are compared.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610060206
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  • 10
    Electronic Resource
    Electronic Resource
    Precipitation of strong uncharged organic acids with various crown ethers or with acyclic polyethers from aqueous medium. Characterization of adducts in the solid state (1993)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 6 (1993), S. 47-53 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: It was found that substituted picric acids form slightly soluble 1 : 2 : 2 adducts with several simple crown ethers or with tri-, tetra-, or pentaethylene glycol dimethyl ether (glymes 4, 5 and 6) in water, whereas 2,4,6-trinitrobenzenesulfonic acid forms a 1 : 1 : 1 adduct with dicyclohexano-18-crown-6 (cis-syn-cis). The ability of a crown ether to precipitate a given acid follows the order dicyclohexano-18-crown-6 (cis-syn-cis) 〉 benzo-15-crown-5 〉 dicyclohexano-24-crown-8 〉 18-crown-6 〉 21-crown-7, 15-crown-5 ≫ 12-crown-4, roughly in the order of its base strength. Precipitation can occur even when the concentration(s) of one or more of the components are 〈 10-4 M. The solubility products of the 18-crown-6 complexes with dichloro- or dimethylpicric acids were estimated. In the solid state the 1 : 2 : 2 dicyclohexano-18-crown-6 (cis-anti-cis)-dichloropicric acid-water complex, which reportedly has two pseudohydronium ions lacking C3v symmetry of H3O+, exhibits an IR spectrum in the OH stretching region characteristic of an aqua complex.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610060108
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