bluuebunny/crossref_metadata_2025_split huggingface dataset:
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aman Spectroscopy in Virus Structure Analysis
Authors: Němeček Daniel , Thomas George J. 
Published: August 2009

Abstract

The structures of complex biological assemblies, such as viruses, and the molecular mechanisms governing virus assembly
in vivo
and
in vitro
require investigation by multiple biophysical techniques. One such technique is Raman spectroscopy, which is particularly useful for probing key steps in the assembly pathways of viruses and for elucidating the molecular structures of viral proteins and nucleic acids. Here, we briefly review the implementation of methods of Raman spectroscopy, including ultraviolet resonance Raman (UVRR) spectroscopy and polarized Raman spectroscopy as structural probes of native viruses, viral precursor assemblies and their constituent proteins, and nucleic acids. We illustrate the powerful analytical approaches of singular value decomposition (SVD) and polarized Raman microspectroscopy for unique quantitative assessments of viral protein structures. Attention is focused on recent applications to bacterial viruses (bacteriophages) of icosahedral (P22 and HK97) and cylindrical (fd, Pf1, Pf3, and PH75) capsid architectures. Methods of Raman spectroscopy provide novel and unique insights into viral macromolecular structures and their transformations that are essential to morphogenesis.
X‐Ray Methods for Investigation of Structures of Lipid Assemblies
Authors: Huang Huey W. , Yang Lin 
Published: August 2009

AbstractOne remarkable characteristic of lipid–water mixtures is their ability to combine in one phase a periodically ordered long‐range organization in one, two, or three dimensions and a disordered short‐range conformation in the unit cells. This unique property makes X‐ray methods ideally suited for the structural determination of lipid assemblies. The unit cell could be a lipid bilayer or a lipidic structure that might occur during a biological process such as membrane fusion or pore formation. In this chapter, we describe methods for resolving the electron density distributions in the unit cells of various lipidic phases, including the lamellar, hexagonal, distorted hexagonal, and rhombohedral phases. The biophysical applications are to determine the structural changes caused by the inclusion of proteins to lipid bilayers. The illustrated examples include changes of the bilayer thickness, distribution of proteins or lipid components in membranes, and monolayer configurations related to membrane fusion and pore formation. The technical sections include sample preparation, diffraction geometry, data reduction, and methods for solving the phase problem, in particular a method of multiwavelength anomalous dispersion uniquely suited for solving lipidic structures.
Ion Channels
Authors: Andersen Olaf S. , Ingólfsson Helgi I. , Lundbæk Jens A. 
Published: August 2009

AbstractIon channels catalyze the transmembrane movement of small inorganic ions across biological membranes. They do so by forming continuous, hydrophilic pores through which ions can cross the barrier imposed by the lipid bilayer hydrophobic core. Ion channels serve many functions: they underlie the changes in membrane potential that control many cell functions, including the propagated electrical signaling (the action potentials) in electrically excitable cells; they allow for the bulk movement of ions across cell membranes. In this chapter, we summarize key features of ion channels, with special emphasis on the channels in the plasma membrane — their structure and catalytic power, the generation of membrane potential changes, the regulation (or gating) that underlies normal channel function, and how channel function can be modulated by small molecules.
Ketonization of 1,5‐Cyclooctadiene by Nitrous Oxide
Authors: Ivanov Dmitry P. , Dubkov Konstantin A. , Babushkin Dmitry E. , Semikolenov Sergey V. , Panov Gennady I. 
Published: August 2009

AbstractThe kinetics and mechanism of the liquid phase ketonization of 1,5‐cyclooctadiene (COD) by nitrous oxide have been studied. The reaction proceeds without catalyst in the temperature range 473–553 K with the activation energy 113 kJ mol−1 and is first order with respect to the initial reactants. The mechanism includes consecutive ketonization of two CC bonds in the COD molecule, with the intermediate formation of an unsaturated monoketone (MK). Further ketonization of MK leads to two isomeric diketones (DK): 1,4‐ and 1,5‐cyclooctanedione. The 1,5‐DK is a stable final product while the 1,4‐DK undergoes further intramolecular aldol transformation leading to two bicyclic compounds, that retain the same number of carbon atoms. The distribution of mono‐ and diketones in the course of reaction is described by theoretical dependences pointing to identical reactivities of the CC double bonds residing in COD and MK molecules. The ketonization of COD by nitrous oxide exemplifies a prospective way for the preparation of valuable organic products in perfect harmony with the strategy of green chemistry.
TEMPO and Carboxylic Acid Functionalized Imidazolium Salts/Sodium Nitrite: An Efficient, Reusable, Transition Metal‐Free Catalytic System for Aerobic Oxidation of Alcohols
Authors: Miao Cheng‐Xia , He Liang‐Nian , Wang Jin‐Quan , Wang Jing‐Lun 
Published: August 2009

AbstractAn effective catalytic system comprising a 2,2,6,6‐tetramethylpiperidine‐1‐oxyl (TEMPO) functionalized imidazolium salt ([Imim‐TEMPO]+ X−), a carboxylic acid substituted imidazolium salt ([Imim‐COOH]+ X−), and sodium nitrite (NaNO2) was developed for the aerobic oxidation of aliphatic, allylic, heterocyclic and benzylic alcohols to the respective carbonyl compounds with excellent selectivity up to >99%, even at ambient conditions. Notably, the catalyst system could preferentially oxidize a primary alcohol to the aldehyde rather than a secondary alcohol to the ketone. Moreover, the reaction rate is greatly enhanced when a proper amount of water is present. And a high turnover number (TON 5000) is achieved in the present transition metal‐free aerobic catalytic system. Additionally, the functionalized imidazolium salts are successfully reused at least four times. This process thus represents a greener pathway for the aerobic oxidation of alcohols into carbonyl compounds by using the present task‐specific ionic liquids in place of the toxic and volatile additive, such as hydrogen bromide, bromine, or hydrogen chloride (HBr, Br2 or HCl), which is commonly required for the transition metal‐free aerobic oxidation of alcohols.
Impact of surface tension and viscosity on solids motion in a conical high shear mixer granulator
Authors: Fan Xianfeng , Yang Zhufang , Parker David J. , Ng Boonho , Ding Yulong , Ghadiri Mojtaba 
Published: August 2009

AbstractSurface tension and viscosity are the important properties of liquid binders affecting wet granulation processes. They could be used to control solids flow pattern and relative motion of particles for controlling wetting, granule growth, consolidation, and breakage. This study aims to investigate experimentally the impacts of the two properties with a conical high shear granulator. The results show significant effects of viscosity and surface tension on solids flow pattern and relative motion of particles. The relative importance of the two parameters, the surface tension and the viscosity, are found to vary with the axial and radial positions in the granulator. For example, the viscosity force decreases with an increase in the bed height in the axial direction (vertical plane). The viscosity force between particles coated with PEG4000 solution is in mN order, whereas that between particles coated with ethanol and water is in μN order. © 2009 American Institute of Chemical Engineers AIChE J, 2009
Theoretical study of a membrane reactor for the water gas shift reaction under nonisothermal conditions
Authors: Adrover María E. , López Eduardo , Borio Daniel O. , Pedernera Marisa N. 
Published: August 2009

AbstractA simulation of a membrane reactor for the water gas shift reaction is carried out by means of a 1D pseudo‐homogeneous nonisothermal mathematical model. The composite membrane consists of a dense layer of Pd (selective to H2) supported over a porous ceramic layer. The effect of temperature, overall heat‐transfer coefficient, and mode of operation on the membrane reactor performance and stability are analyzed, and the results obtained are compared with those corresponding to a reactor with no hydrogen permeation. © 2009 American Institute of Chemical Engineers AIChE J, 2009
A novel dual circulating fluidized bed system for chemical looping processes
Authors: Pröll Tobias , Kolbitsch Philipp , Bolhàr‐Nordenkampf Johannes , Hofbauer Hermann 
Published: August 2009

AbstractA fluidized bed system combining two circulating fluidized bed reactors is proposed and investigated for chemical looping combustion. Direct hydraulic communication of the two circulating fluidized bed reactors via a fluidized loop seal allows for high rates of global solids circulation and results in a stable solids distribution in the system. A 120 kW fuel power bench scale unit was designed, built, and operated. Experimental results are presented for natural gas as fuel using a nickel‐based oxygen carrier. No carbon was lost to the air reactor under any conditions operated. It is shown from fuel power variations that a turbulent/fast fluidized bed regime in the fuel reactor is advantageous. Despite the relatively low riser heights (air reactor: 4.1 m, fuel reactor: 3.0 m), high CH4conversion and CO2yield of up to 98% and 94%, respectively, can be reported for the material tested. © 2009 American Institute of Chemical Engineers AIChE J, 2009
Experimental investigation on evaporation of urea‐water‐solution droplet for SCR applications
Authors: Wang Tae Joong , Baek Seung Wook , Lee Seung Yeol , Kang Dae Hwan , Yeo Gwon Koo 
Published: August 2009

AbstractThe evaporation behavior of urea‐water‐solution (UWS) droplet was investigated for application to urea‐selective catalytic reduction (SCR) systems. A number of experiments were performed with single UWS droplet suspended on the tip of a fine quartz fiber. To cover the temperature range of real‐world diesel exhausts, droplet ambient temperature was regulated from 373 to 873 K using an electrical furnace. As a result of this study, UWS droplet revealed different evaporation characteristics depending on its ambient temperature. At high temperatures, it showed quite complicated behaviors such as bubble formation, distortion, and partial rupture after a linear D2‐law period. However, as temperature decreases, these phenomena became weak and finally disappeared. Also, droplet diminishment coefficients were extracted from transient evaporation histories for various ambient temperatures, which yields a quantitative evaluation on evaporation characteristics of UWS droplet as well as provides valuable empirical data required for modeling or simulation works on urea‐SCR systems. © 2009 American Institute of Chemical Engineers AIChE J, 2009
Synthesis, structure, and selective separation behavior of copper‐imprinted microporous polymethacrylate beads
Authors: Hoai Nguyen To , Kim Dukjoon 
Published: August 2009

AbstractMetal ion‐imprinted polymethacrylate beads with sizes ranging from 100 to 300 μm were prepared by suspension polymerization for the application of selective separation of target metal ions. The metal ion contacting area of the beads was enlarged via pore formation (BET 425 m2/g) using toluene as a porogenic agent. The synthesis of the copper‐imprinted porous beads was verified using FTIR, SEM, and ESCA. Separation capacity and selectivity were investigated carrying out column separation experiments. The selective adsorption behavior of the imprinted beads was significantly affected by flow rate, pH, and metal ion concentration in the solution. Adsorption of the copper ion, the template metal ion, onto the beads was highly selective, compared with other ions such as nickel and zinc, with the selective coefficients at approximately 5–10. The microporous particles possessing such high selectivity has a potential application as novel column packing materials especially requiring high selective efficiency, which is usually not achievable by commercial ion exchange resins. © 2009 American Institute of Chemical Engineers AIChE J, 2009
Beryllium lymphocyte proliferation test surveillance identifies clinically significant beryllium disease
Authors: Mroz Margaret M. , Maier Lisa A. , Strand Matthew , Silviera Lori , Newman Lee S. 
Published: August 2009

AbstractBackgroundWorkplace surveillance identifies chronic beryllium disease (CBD) but it remains unknown over what time frame mild CBD will progress to a more severe form.MethodsWe examined physiology and treatment in 229 beryllium sensitization (BeS) and 171 CBD surveillance‐identified cases diagnosed from 1982 to 2002. Never smoking CBD cases (81) were compared to never smoking BeS patients (83) to assess disease progression. We compared CBD machinists to non‐machinists to examine effects of exposure.ResultsAt baseline, CBD and BeS cases did not differ significantly in exposure time or physiology. CBD patients were more likely to have machined beryllium. Of CBD cases, 19.3% went on to require oral immunosuppressive therapy. At 30 years from first exposure, measures of gas exchange were significantly worse and total lung capacity was lower for CBD subjects. Machinists had faster disease progression as measured by pulmonary function testing and gas exchange.ConclusionsMedical surveillance for CBD identifies individuals at significant risk of disease progression and impairment with sufficient time since first exposure. Am. J. Ind. Med. 52:762–773, 2009. © 2009 Wiley‐Liss, Inc.
Gene therapy and protein therapy of ectodermal dysplasias: A perspective
Authors: Gaide Olivier 
Published: August 2009

AbstractEctodermal dysplasias (EDs) form a complex and heterogeneous group of diseases currently defined and classified according to their clinical symptoms. The characterization, for several EDs, of the molecular events underlying their development, not only challenges this classification but also opens the door to new therapeutic options such as gene or protein therapy. This article provides a concise overview of the most recent successes and failures of this new type of treatment and sets in perspective how the specificities of given EDs will influence their feasibility in the near future. It makes the case for the need of new classification of EDs that is based on our most recent knowledge of the molecular basis of these diseases. © 2009 Wiley‐Liss, Inc.
2008 International Conference on Ectodermal Dysplasias Classification: Conference report
Authors: Salinas Carlos F. , Jorgenson Ronald J. , Wright J. Timothy , DiGiovanna John J. , Fete Mary D. 
Published: August 2009

AbstractThere are many ways to classify ectodermal dysplasia syndromes. Clinicians in practice use a list of syndromes from which to choose a potential diagnosis, paging through a volume, such as Freire‐Maia and Pinheiro's corpus, matching their patient's findings to listed syndromes. Medical researchers may want a list of syndromes that share one (monothetic system) or several (polythetic system) traits in order to focus research on a narrowly defined group. Special interest groups may want a list from which they can choose constituencies, and insurance companies and government agencies may want a list to determine for whom to provide (or deny) health‐care coverage. Furthermore, various molecular biologists are now promoting classification systems based on gene mutation (e.g., TP63‐associated syndromes) or common molecular pathways. The challenge will be to balance comprehensiveness within the classification with usability and accessibility so that the benefits truly serve the needs of researchers, health‐care providers, and ultimately the individuals and families directly affected by ectodermal dysplasias. It is also recognized that a new classification approach is an ongoing process and will require periodical reviews or updates. Whatever scheme is developed, however, will have far‐reaching application for other groups of disorders for which classification is complicated by the number of interested parties and advances in diagnostic acumen. Consensus among interested parties is necessary for optimizing communication among the diverse groups whether it be for equitable distribution of funds, correctness of diagnosis and treatment, or focusing research efforts. © 2009 Wiley‐Liss, Inc.
Katalytische C‐C‐, C‐N‐ und C‐O‐Ullmann‐Kupplungen
Authors: Monnier Florian , Taillefer Marc 
Published: August 2009

AbstractKupferkatalysierte Ullmann‐Kondensationen sind Schlüsselreaktionen in der organischen Synthese zur Bildung von Kohlenstoff‐ Heteroatom‐ und Kohlenstoff‐Kohlenstoff‐Bindungen. Die mit diesen Methoden erhältlichen Strukturmotive sind in biologisch aktiven Molekülen und vielen Materialvorstufen weit verbreitet. Dementsprechend waren intermolekulare Ullmann‐Reaktionen zur Kupplung von Aryl‐ und Vinylhalogeniden mit N‐, O‐ und C‐Nucleophilen Gegenstand zahlreicher Studien, und dieser Kurzaufsatz beleuchtet die aktuellsten und wichtigsten Entwicklungen auf diesem Gebiet seit 2004.
Effect of ceramic nanoadditive content and type on the rheological properties of poly(vinyl alcohol) spinning solutions
Authors: Boguń Maciej , Mikołajczyk Teresa 
Published: August 2009

AbstractRheological properties of aqueous PVA solutions within a wide concentration range have been examined to select a concentration at which apparent dynamic viscosity is suitable for fiber spinning from solution by the wet process. The rheological properties of PVA solutions containing various quantities of nanosilica and nanohydroxyapatite were assessed. It has been found that an increase in the quantity of both types of nanoadditives from 1 to 5% brings about a decrease in the value of the rheological parameter n and enhances the polymeric character of the fluid. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Natural rubber/poly(acrylic acid) semi‐interpenetrating polymer network membranes for the pervaporation of water–ethanol mixtures
Authors: Amnuaypanich Sittipong , Kongchana Nuchjarin 
Published: August 2009

AbstractPervaporation membranes for the dehydration of water–ethanol mixtures were prepared from a semi‐interpenetrating polymer network (semi‐IPN) of natural rubber (NR) and crosslinked poly(acrylic acid) (PAA). The swelling studies revealed that hydrophilic PAA present in the semi‐IPN membranes caused the membranes to swell greatly in water. The swelling degree of the membranes in water was significantly affected by the amount ratio between the hydrophobic NR and the hydrophilic PAA. The sorption experiments of the NR/PAA membranes in various concentrations of water–ethanol mixtures suggested the preferential sorption to water. However, for the membrane with high PAA content, the water sorption selectivity decreased considerably at high water concentration of water–ethanol mixtures because the membrane was in the highly swollen state. Pervaporation separations of water–ethanol mixtures using NR/PAA membranes were performed and it was found that at low water concentrations of feed mixtures, increasing the PAA content of the membrane can enhance both water permeation flux and selectivity. Additionally, under low feed water concentration, increasing the feed temperature would increase the water flux with the decreasing of the ethanol flux. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Influence of polyacrylate/titanium dioxide composite particles on the antiaging performance of polycarbonates
Authors: Han Shi‐Min , Yang Ming‐Jiao , Gao Wei‐Bin , Tang Ming‐Jing , Jiang Long , Dan Yi 
Published: August 2009

AbstractPolycarbonate (PC) and PC modified by polyacrylate/TiO2 composite particles were exposed both in an outdoor environment with typical humid and hot climatic conditions in the Jiangjin area and in an indoor hygrothermal environment for accelerated aging. Then, the effects of the polyacrylate/TiO2 composite particles on the antiaging performance of PC were investigated by measurement of the mechanical properties of PC before and after aging. The results show that the mechanical properties of PC decreased a lot after aging by the outdoor environment of the Jiangjin area. After accelerated aging by the indoor hygrothermal environment, the tensile strength and the bending strength of PC increased a little, and the elongation at break of PC decreased. The polyacrylate/TiO2 composite particles effectively increased the elongation at break of PC aged by the hygrothermal environment and outdoor aging. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Large‐scale synthesis of polyaniline nanofibers based on renewable resource molecular template
Authors: Anilkumar P. , Jayakannan M. 
Published: August 2009

AbstractWe report reproducible large‐scale synthesis of polyaniline (PANI) nanofibers up to 100 g scale via micelle mediated soft template approach. A unique built‐in amphiphilic azobenzenesulfonic acid based on renewable resource dopant was synthesized for large‐scale production of PANI nanofibres. The amphiphilic surfactant exists as 4.3 nm micelle in water and it self‐organized with aniline to form long cylindrical aggregates, which template for PANI nanofibers. The PANI nanofibers were found soluble in water and organic solvents and they were characterized by 1H‐NMR, FT‐IR, and viscosity techniques. The mechanism of the PANI nanofiber formation was investigated by dynamic light scattering, scanning electron microscopy, and high resolution transmission electron microscopy. The width of the nanofibers was precisely controlled from 130–200 nm with length up to ∼ 5 μm. The absorption spectroscopic analysis of nanofibers in water revealed that the large‐scale samples (10, 50, and 100 g) were found to posses expanded chain conformation compared to that of 1 g scale sample. The wide angle X‐ray diffraction patterns showed two new peaks at lower angles at d spacing of 25.5 and 13.6 Å corresponding to lamellar ordering of PANI chains followed by interdigitation of the amphiphilic dopant in the nanofibers. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Influence of hybridization of glass fiber and talc on the mechanical performance of polypropylene composites
Authors: Morelli Carolina L. , Pouzada António S. , Sousa José A. 
Published: August 2009

AbstractThe effect of the hybridization of short glass fibers (GFs) and talc mineral filler on the tensile mechanical performance of injection‐molded propylene‐ethylene copolymer composites (PPcop) with and without weld lines (WLs) was studied in this work. The fibrous reinforcement imparts high‐tensile stiffness and strength to the molding but originates a highly anisotropic composite. The negative effect of this anisotropy is even worse when WLs occur in the molding, as the high aspect ratio GFs tend to be oriented on the weak plane of the WL. Through hybridization of GF and talc, combined in different proportions, it is possible to obtain improved mechanical properties in comparison to the standard GF reinforced PPcop composites. The combination of GF with talc was shown to be beneficial for the WL strength of PPcop composites, once a synergism effect was achieved with the expected optimization of the fibers/particles packing efficiency of the hybrid reinforcement. At a given constant total reinforcement concentration, the experimental data of both tensile modulus and strength properties of the hybrid composites without WL were above the predictions derived from the estimated rule of mixtures. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009