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molecular docking of superantigens with class II major histocompatibility complex proteins

Journal of molecular Recognition 1998年第6期10卷

作者： Mark A. Olson Lilee Cuff Molecular Modeling Laboratory Department of Cell Biology and Biochemistry USAMRIID 1425 Porter Street Frederick Maryland 21702 USA Department of Chemical Engineering and Materials Science University of Minnesota Minneapolis MN 55415 USA

The molecular recognition of two superantigens with class II major histocompatibility complex molecules was simulated by using protein– protein docking. Superantigens studied were staphylococcal enterotoxin B (SEB) and toxic shock syndrome toxin-1 (TSST-1) in their crystallographic assemblies with HLA-DR1. Rigid-body docking was performed sampling configurational space of the interfacial surfaces by employing a strategy of partitioning the contact regions on HLA-DR1 into separate molecular recognition units. Scoring of docked conformations was based on an electrostatic continuum model evaluated with the finite-difference Poisson– Boltzmann method. Estimates of nonpolar contributions were derived from the buried molecular surface areas. We found for both superantigens that docking the HLA-DR1 surface complementary with the SEB and TSST-1 contact regions containing a homologous hydrophobic surface loop provided sufficient recognition for the reconstitution of native-like conformers exhibiting the highest-scoring free energies. For the SEB complex, the calculations were successful in reproducing the total association free energy. A comparison of the free-energy determinants of the conserved hydrophobic contact residue indicates functional similarity between the two proteins for this interface. Though both superantigens share a common global association mode, differences in binding topology distinguish the conformational specificities underlying recognition. © 1998 John Wiley & Sons, Ltd.

关键词： protein–protein docking surface complementarity binding free energy molecular recognition electrostatics hydrophobic effect

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Sedimentation‐resistant electrorheological fluids based on PVAL‐coated microballoons

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Journal of Applied Polymer science 1998年第3期65卷

作者： Mancun Qi Montgomery T. Shaw Department of Chemical Engineering University of Connecticut Storrs Connecticut 06269‐3136 Polymer Science Program Institute of Materials Science University of Connecticut 97 North Eagleville Road U‐136 Storrs Connecticut 06269‐3136

Sedimentation is often a problem in electrorheological (ER) fluids featuring solid particles suspended in a low‐density hydrocarbon oil. This problem was addressed by synthesizing particles comprising silica microballoons coated with PVAL using a salt‐induced coacervation process. The ER performance of the fluids based on these particles was equivalent to prototypical commercial fluids, both with respect to current leakage and shear stress under steady simple shear flow. For comparing diverse fluids as to these practical characteristics, a dimensionless ER effectiveness number, Er, was proposed: Er = σγ˙/ EJ where σ is the shear stress, γ˙ is the electric field, and J is the current. The resulting uniform coatings were also found to impart a degree of resistance to breakage. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65:539–547, 1997

关键词： ER fluids electrorheology PVAL‐coated microballoons ER effectiveness number sedimentation attrition

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A relationship between the glass transition temperature (Tg) and fractional conversion for thermosetting systems

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Journal of Applied Polymer science 1998年第1期64卷

作者： R. A. Venditti J. K. Gillham Department of Wood and Paper Science North Carolina State University Box 8005 Raleigh North Carolina 27695‐8005 Polymer Materials Program Department of Chemical Engineering Princeton University Princeton New Jersey 08544

An equation, based on thermodynamic considerations to relate the glass transition temperature, T g , to compositional variation of a polymer system, is adapted in this article for modeling the T g vs. fractional conversion ( x ) relationship of reactive thermosetting systems. Agreement between the adapted equation and experimental T g vs. x data is found for several thermosetting crosslinking systems (i.e., epoxies and cyanate ester/polycyanurate) as well as for reactive thermosetting linear polymer systems (i.e., polyamic acid and esters to polyimides). The equation models the experimentally obtained T g vs. x behavior of thermosetting systems which include competing reactions. Agreement for widely varying molecular structures demonstrates the generality of the equation. The entire T g vs. x relationship can be predicted for a thermosetting material by using the T g vs. x equation and the values of the initial glass transition temperature, T g 0 , the fully reacted system glass transition temperature, T g∞ , and the ratio of the change in specific heat from the liquid or rubbery state to the glassy state (Δ c p ) at T g 0 and T g∞ , Δ c p∞ /Δ c p 0 . The values of T g 0 , T g ∞ , and Δ c p∞ /Δ c p 0 can be measured generally from two differential scanning calorimetric experiments. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 3–14, 1997

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Advantages of self-propagating combustion reactions for synthesis of oxide phosphors

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Journal of the Society for Information Display 1997年第2期5卷 117-125页

作者： Shea, L.E. McKittrick, J. Lopez, O.A. Sluzky, E. Phillips, M.L.F. Optoelectronics Characterization and Sensor Development Sandia National Laboratories Albuquerque NM Department of Applied Mechanics and Engineering Sciences University of California at San Diego La Jolla CA Materials Science Program University of California at San Diego La Jolla CA Department of Chemical Engineering and Materials Sciences University of California Davis CA Deacon Research in Palo Alto CA

Combustion synthesis was explored as an alternate synthetic route to producing oxide phosphors with improved luminescent properties. The technique involves the highly exothermic reaction of metal nitrates (oxidizers) with an organic fuel (e.g., urea, carbohydrazide, glycine) at 500 °C. We have synthesized Tb3+, Eu3+, Tm3+ and Cr3+-activated Y3Al5O12 (YAG), Y2O3:Eu3+, and Y2SiO5:Ce3+ phosphors. As-reacted powders are well-crystallized, luminescent, and have a small particle size. The effects of processing parameters such as type of fuel and fuel/oxidizer ratio on the spectral energy distribution were determined using photoluminescence measurements. Low-voltage (100-1000 V) efficiency of combustion-synthesized phosphors was compared with efficiencies obtained for phosphors prepared via hydrothermal synthesis and high-temperature solid-state reaction.

关键词： Phosphors

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Moisture effects on the behavior of graphite/polyimide composites

Moisture effects on the behavior of graphite/polyimide compo...

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作者： Burcham, Loyd J. VanLandingham, Mark R. Eduljee, Rushad F. Gillespie, John W. Department of Chemical Engineering Materials Science Program Center for Composite Materials University of Delaware NewarkDE19716 United States Department of Chemical Engineering Lehigh University BethlehemPA18015 United States

The effect of moisture on the material behavior of Magnamite® IM7 Graphite/Avimid® K3B thermoplastic polyimide composite laminates has been investigated. Laminates consisting of a 62 vol% fiber were laid up with several different stacking sequences: [90]10 or unidirectional, [02/90]S or thin cross-ply, [02/902/02]S or thick cross-ply, [45/0/-45/90]S or quasi-isotropic, and [0/90] laminates. In this study, the glass-transition temperature, Tg, and the intralaminar fracture toughness, GIC, were measured for dry and moisture-saturated unidirectional samples. When laminates were saturated with moisture, the value of Tg was found to decrease from its baseline (dry) value, but recovered upon redrying the samples. This observation is consistent with the effects of moisture on the Tg of other polymer composites. Permanent toughness losses have not been observed in samples conditioned in room-temperature 75% and 100% relative humidity environments. However, during long-term conditioning of cross-ply and quasi-isotropic samples in liquid water, transverse cracks initiated in the absence of an applied mechanical load. Moisture uptake curves for conditioning in room-temperature liquid water, 80°C (176°F) liquid water, and at room temperature and 75% relative humidity were used to calculate Henry's Law constants and diffusion coefficients. Non-Fickian behavior, consisting of a postsaturation increase in moisture uptake, was observed in crossply and quasi-isotropic laminates and might be due to the observed transverse cracking. Copyright © 1996 Society of Plastics Engineers.

关键词： Moisture

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Structure in a Confined Smectic Liquid Crystal with Competing Surface and Sample Elasticities

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Physical Review Letters 1996年第9期76卷 1477-1477页

作者： Stefan H. J. Idziak Ilya Koltover Jacob N. Israelachvili Cyrus R. Safinya Materials Department Materials Research Laboratory Physics Department and Biochemistry and Molecular Biology Program University of California Santa Barbara California 93106 Department of Chemical Engineering Materials Department and Materials Research Laboratory University of California Santa Barbara California 93106

We report on studies using the x-ray surface forces apparatus (XSFA) to compare the structure of a liquid crystal confined between hard surfaces and, for the first time, between soft surfaces that can deform due to the stresses imposed by the confined fluid. We find that the alignment of smectic domains in confined films depends critically on both the shape and compliance of the confining walls or surfaces: “Soft surfaces” exhibit a critical gap thickness of 3.4 μm for the liquid crystal studied at which maximum alignment occurs, while “hard surfaces” do not exhibit gap-dependent alignment.

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Dielectric monitoring of epoxy cure

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Journal of Polymer science 1996年第16期34卷

作者： G. Levita A. Livi P. A. Rolla C. Culicchi Department of Industrial Chemistry and Chemical Engineering Polytechnic of Milan Institute for Atomic and Molecular Physics IFAM-CNR Pisa National Institute for Physics of Matter and Department of Physics University of Pisa Piazza Torricelli 2 56126 Pisa Italy Department of Chemical Engineering Industrial Chemistry and Materials Science University of Pisa Italy

The cure process of mixtures of a DGEBA-type epoxy resin and ethylenediamine, in different molar ratios, was investigated by dielectrometry in a wide frequency range, 10 3 -2·10 10 Hz, at three temperatures, 25, 60, and 70°C. Two relaxation processes were found whose relevant parameters were obtained by a proper fit procedure. A deeper knowledge and a quantitative description of the observed effects was achieved by analyzing the change of dielectric data caused by the chemical reaction. The change of the dielectric strength of both processes, as well as of other dielectric parameters, reflect the chemical modifications of the system; the permittivity, both static and at microwave frequencies, was linearly related to the conversion. These results support the interpretative model based on the disappearance of dipoles, and confirm the permittivity as a valuable quantity to monitor the kinetics of the reaction. © 1996 John Wiley & Sons, Inc.

关键词： dielectric monitoring epoxy cure microwave dielectrometry

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Abstract

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Pflügers Archiv 1996年第6期431卷 R322-R356页

作者： L. J. Andries S. U. Sys A. L. Meulemans J. A. J. Schuurkes B. Vanheel J. Van de Voorde P. De Smet J. Li W. Van Driessche B. Flamion S. Foulon M. Abramow P. Calders W. Eechaute E. Lacroix I. Weyne D. Hoeben C. Burvenich P. Fransen D. Van Bedaf M. Demolder R. Ouedraogo P. Lebrun A. Herchuelz M. -H. Antoine S. Vandenput D. Votion N. Anciaux D. H. Duvivier T. Art P. Lekeux Y. Ghafir M. Geurts E. Hermans J. -M. Maloteaux B. Perrad B. Noel F. Lagache J. L. Bister R. Paquay G. Derycke M. A. Vandermeir S. de Brouwer C. -A. Porret N. Stergiopulos J. -J. Meister M. Verbeke N. Lameire N. M. De Clerck J. De Schuytter J. Tytgato G. Buyse J. Eggermont G. Droogmans B. Nilius P. Daenens S. Salomone O. Feron C. Dessy N. Morel T. Godfraind A. M. Aloisi P. Sacerdote L. Lodi G. Carli C. Carobi G. Garinei U. C. Miniaci P. Scotto M. Sabatino P. Sardo L. Iurato V. La Grutta M. A. Bagni G. Cecchi E. Cecchini F. Colomo P. Garzella R. Bottinelli S. D. H. Harridge M. Canepari C. Reggiani Saltin Reggiani D. Bambagioni G. Fanò G, Menchetti P. Danieli-Betto A. Esposito R. Betto A. Megighian M. Midrio D. Danieli Betto C. Orizio D. Liberati C. Locatelli D. De Grandis A. Veicsteinas D. Angoli D. Delia E. Wanke M. Bramucci A. Miano L. Quassinti E. Maccari O. Murri D. Amici G. Cibelli S. Jüngling S. Schoch H. H. Gerdest G. Thiel I. Demori C. Bottazzi A. Voci E. Fugassa A. Barreca F. Minuto G. Gallo S. Fulle S. Belia G. Menchetti M. Cacchio G. Gastaldi U. Laforenza G. Ferrari G. Rindi M. G. Doni E. Padoin O. Residori M. Cesaro L. Toma A. Rubini F Mutinelli L. Paulesu R. Romagnolie M. Cintorino P. Pippia M. A. Meloni L. Sciola A. Spano M. Cogoli-Greuter A. Cogoli A. Sardini G. M. Mintenig M. A. Valverde F. V. Sepùlveda D. R. Gill S. C. Hyde C. F. Higgins P. A. McNaughton A. Spena M. T. Arcuri S. Bonofiglio R. Chimenti C. Covello T. De Cicco S. Mazzulla G. Martino A. Tottene A. Moretti D. Pietrobon M. C. Baccari F. Calamai G. Staderini E. Cova R. Marelli P. Sommi U. Ventura A. M. Lombardi R. Fabris C. Pagano G. Federspil R. Vettor R. Mancinelli P. To Laboratory of Physiology RUCA University of Antwerp Belgium Dept. of Gastroint. Pharmacol. Janssen Research Foundation Beerse Belgium Department of Physiology and Physipathology University of Gent De Pintelaan 185 Gent Belgium Laboratory of Physiology K. U. Leuven Leuven Belgium Laboratory of Pathophysiology University of Bruxelles (ULB) Brussels Belgium Laboratory of Normal and Pathological Physiology University of Gent Belgium Department of Physiology Biochemistry and Biometrics Faculty of Veterinary Medicine University of Ghent Merelbeke Belgium Laboratory of Physiology University of Antwerp (RUCA) Antwerp Belgium Lab. de Pharmacodynamie et de Thérapeutique Université Libre de Bruxelles Bruxelles Belgique Laboratory for Functional Investigation Faculty of Veterinary Medicine University of Liége Liège Belgium Laboratory for Functional Investigation Faculty of Veterinary Medicine University of Liège Liège Belgium Laboratory of Pharmacology Catholic University of Louvain Brussels Laboratoire de Physiologie Animale FUNDP Namur Laboratory of animal Physiology Facultés universitaires Notre-Dame de la Paix Namur Belgium Biomedical Engineering Laboratory Swiss Federal Institute of Technology Lausanne Switzerland RUCA University of Antwerp Antwerp Belgium Laboratory of Physiology Laboratory of Toxicology University of Leuven Leuven Belgium Laboratoire de Pharmacologie Université Catholique de Louvain Bruxelles Belgium Istituto di Fisiologia Umana Università degli Studi Siena Dipartimento di Farmacologia Università degli Studi di Milano Milano Istituto di Fisiologia Umana Università di Perugia Perugia Dipartimento di Medicina Sperimentale Università di Reggio Calabria Laboratorio di Fisiologia Umana Catanzaro Istituto di Fisiologia umana Palermo Dipartimento di Scienze Fisiologiche Università di Firenze Firenze Dipartimento Biologia Cellulare e Molecolare (sez. Fisiologia e Biofisica) Università di Perugia Perugia Istituto di Fisiologia Umana Univer

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Synthesis and processing of nanostructured M50 type steel

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Nanostructured materials 1994年第2期4卷 139-139页

作者： Gonsalves, K.E. Xiao, T.D. Chow, G.M. Law, C.O. Polymer Science Program Institute of Materials Science and Department of Chemistry University of Connecticut Storrs CT 06269 USA Connecticut Advanced Technology Center for Precision Manufacturing University of Connecticut Storrs CT 06269 USA Center for Bio/Molecular Science and Engineering Naval Research Laboratory Washington D.C. 20375 USA Pratt & Whitney United Technologies Corporation East Hartford CT 06108 USA

A nanostructured FeCrMoVM50 type steel was prepared via a chemical route. The process involved the thermal decomposition of organometallic precursors Fe(CO) 5 , Cr(CO) 6 , Mo(CO) 6 and V(CO) 6 , at 150°C for the formation of nanostructured M50 type steel powders. In addition to the thermal decomposition of these carbonyls, the results of the reduction of respective metal halides for the production of the same steel are also presented. The nanostructured steel powders obtained were also consolidated samples, were characterized using x-ray synthesized powders, as well as the consolidated samples, were characterized using x-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and high resolution electron microscopy (HRTEM). Possible mechanisms for the formation of nanostructured particles are also discussed.

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Substrate Influenced Nucleation and Crystallization of LinbO 3 Thin Films Made by Sol-Gel

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MRS Online Proceedings Library 1993年第1期310卷 287-292页

作者： Vikram Joshi Debasis Roy Martha L. Mecartney Department of Chemical Engineering and Materials Science University of Minnesota Minneapolis USA Materials Science and Engineering Program University of California Irvine USA

Lithium niobate films were deposited on amorphous carbon, silicate glass, (0001) sapphire, and (100) silicon by spin or dip coating double metal ethoxide sols. The crystallinity and microstructure of the deposited films were examined by XRD and ТЕМ. Crystallization behavior and resulting microstructure were strongly influenced by the type of substrate. The formation of crystalline LiNbO3 on amorphous carbon was detected at room temperature. Randomly oriented polycrystalline films were obtained on glass at 400°C. Choice of one mole of water per mole of ethoxide generated heteroepitaxial growth of LiNbO3 thin films on (0001) sapphire. Oriented but polycrystalline films were obtained on silicon. The electrical behavior of film on silicon was evaluated in metal-ferroelectric-semiconductor configuration. A dielectric constant of 35 and a dissipation factor of 0.004 was measured at 100 KHz.

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