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  • 1
    Publication Date: 2012-01-24
    Description: Multidentate, noncovalent interactions between small molecules and biopolymer fragments are central to processes ranging from drug action to selective catalysis. We present a versatile and sensitive spectroscopic probe of functional groups engaged in hydrogen bonding in such contexts. This involves measurement of the frequency changes in specific covalent bonds upon complex formation, information drawn from otherwise transient complexes that have been extracted from solution and conformationally frozen near 10 kelvin in gas-phase clusters. Resonances closely associated with individual oscillators are easily identified through site-specific isotopic labeling, as demonstrated by application of the method to an archetypal system involving a synthetic tripeptide known to bind biaryl substrates through tailored hydrogen bonding to catalyze their asymmetric bromination. With such data, calculations readily converge on the plausible operative structures in otherwise computationally prohibitive, high-dimensionality landscapes.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4038764/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4038764/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Garand, Etienne -- Kamrath, Michael Z -- Jordan, Peter A -- Wolk, Arron B -- Leavitt, Christopher M -- McCoy, Anne B -- Miller, Scott J -- Johnson, Mark A -- R01-GM068649/GM/NIGMS NIH HHS/ -- R37 GM068649/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 2012 Feb 10;335(6069):694-8. doi: 10.1126/science.1214948. Epub 2012 Jan 19.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Sterling Chemistry Laboratory, Yale University, Post Office Box 208107, New Haven, CT 06520, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/22267579" target="_blank"〉PubMed〈/a〉
    Keywords: Binding Sites ; Biphenyl Compounds/*chemistry ; Catalysis ; Freezing ; Gases ; Halogenation ; Hydrogen Bonding ; Infrared Rays ; Molecular Conformation ; Molecular Structure ; Oligopeptides/*chemistry ; Physicochemical Processes ; Spectrum Analysis/*methods ; Stereoisomerism
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 2
    Publication Date: 2014-09-27
    Description: Ozonolysis of alkenes, an important nonphotolytic source of hydroxyl (OH) radicals in the troposphere, proceeds through energized Criegee intermediates that undergo unimolecular decay to produce OH radicals. Here, we used infrared (IR) activation of cold CH3CHOO Criegee intermediates to drive hydrogen transfer from the methyl group to the terminal oxygen, followed by dissociation to OH radicals. State-selective excitation of CH3CHOO in the CH stretch overtone region combined with sensitive OH detection revealed the IR spectrum of CH3CHOO, effective barrier height for the critical hydrogen transfer step, and rapid decay dynamics to OH products. Complementary theory provides insights on the IR overtone spectrum, as well as vibrational excitations, structural changes, and energy required to move from the minimum-energy configuration of CH3CHOO to the transition state for the hydrogen transfer reaction.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Liu, Fang -- Beames, Joseph M -- Petit, Andrew S -- McCoy, Anne B -- Lester, Marsha I -- New York, N.Y. -- Science. 2014 Sep 26;345(6204):1596-8. doi: 10.1126/science.1257158.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104-6323, USA. ; Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210-1173, USA. ; Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104-6323, USA. milester@sas.upenn.edu.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/25258077" target="_blank"〉PubMed〈/a〉
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 3
    ISSN: 1612-1112
    Keywords: Gas-liquid-solid chromatography ; Partitioning ; Adsorption ; Mass transfer ; Retention ; Variance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The resolution of gaseous chemical species in gasliquid-solid chromatography is influenced by absorption (partitioning) in the liquid and adsorption at the liquid-solid interface. We consider fundamental mass transfer models with adsorption and partitioning effects for solid chromatographic supports covered with thin films of stationary liquid. The dynamic models, based on mass-balance partial-differential equations, include the significant phenomena: convection, axial dispersion, gas-liquid mass transfer, intraparticle diffusion, and liquid-solid adsorption. Expressions for retention time and band variance (first and second temporal moments) are presented and evaluated for four distinct models: (1) capillary tube with inner surface covered with a uniform-thickness liquid film, (2) column of nonporous spheres covered with a uniform-thickness liquid film, (3) porous spherical particles with intraparticle pores covered with a uniform-thickness liquid film, (4) porous spherical particles with intraparticle pores completely filled with liquid.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of food science 38 (1973), S. 0 
    ISSN: 1750-3841
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Notes: At higher temperatures reverse osmosis membrane coefficients increase and cause permeation rates to increase. Diffusion coefficients also increase and viscosity coefficients decrease causing concentration polarization to decrease and improve permeation. Experiments were performed with 15% (w/w) sucrose solutions in tubular cellulose acetate reverse osmosis membranes at 500 psig for low flow rates (Reynolds numbers between 10 and 1000). Depending upon the flow rate and mode of heating, raising the temperature from 25 to 35°C increased permeation rates up to 20%, and from 25 to 45°C up to 55%. Two methods of heating were tested: preheating the entire feed to the system, and heating the boundary layer at the membrane surface. Comparisons with theory are discussed
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of food science 40 (1975), S. 0 
    ISSN: 1750-3841
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Clinica Chimica Acta 225 (1994), S. 97-103 
    ISSN: 0009-8981
    Keywords: Newborn infants ; Vitamin E ; Whole blood clotting time
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 19 (1973), S. 1068-1070 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 28 (1982), S. 844-847 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Dynamic experiments provide an opportunity to determine, separately, values of the adsorption and surface reaction rates occurring in a heterogeneous, catalytic reaction. In this method it is not necessary to assume that either adsorption, surface reaction, or desorption controls the rate, in contrast to the procedure used for analyzing steady state rate data.The dynamic method is applied to experimental data for the oxidation of sulfur dioxide in a three-phase aqueous-slurry reactor using activated carbon as the catalyst. The results for 274.5 K show that both rates of reversible adsorption of oxygen and the subsequent, irreversible surface reaction affect the overall rate. Neither process can be considered to be controlling.The data required for the analysis are the zero and first moments of the response in the effluent gas to a disturbance in the feed, the adsorption equilibrium constant for oxygen, and appropriate mass transfer coefficients.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 31 (1985), S. 1572-1574 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Regular perturbation theory is applied to determine the response to an impulse input in a continuous-flow stirred-tank reactor (CSTR) with nonlinear adsorption. A series expansion for temporal moments is a result of the procedure. This moment expansion allows the usual restriction of linearity in analysis of experimental data by moments to be waived. The response at each order can be expressed as an expansion in Laguerre polynomials involving moments, which, in the present example, converges to the exact solution.
    Type of Medium: Electronic Resource
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