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Appropriate Selection (appropriate + selection)
Selected AbstractsStereodivergent Addition of Allylmetal Reagents to Imines Derived from (R)-2,3-Di-O-benzylglyceraldehyde by Appropriate Selection of Metal and Double Stereodifferentiation.CHEMINFORM, Issue 7 2003Ramon Badorrey Abstract For Abstract see ChemInform Abstract in Full Text. [source] Novel Anion Exchangers for Electrodes with Improved Selectivity to Divalent AnionsELECTROANALYSIS, Issue 17 2004Vladimir Egorov Abstract It has been found that replacing of several long-chain alkyl substituents at the nitrogen atom of lipophilic quaternary ammonium salts (QAS) by methyls results in a dramatic increase of the potentiometric selectivity of ion-selective electrodes (ISE) with QAS-based plasticized PVC membranes to some divalent anions against the monovalent ones. The discussed effect of QAS cation nature on the potentiometric selectivity is also partly retained for ISE with neutral carrier-based membranes doped with QAS to provide anion permselectivity. This opens up new possibilities to control the potentiometric selectivity of ISE for divalent anions by the appropriate selection of the anion exchanger. [source] Quantitative structure-activity relationship methods: Perspectives on drug discovery and toxicologyENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 8 2003Roger Perkins Abstract Quantitative structure,activity relationships (QSARs) attempt to correlate chemical structure with activity using statistical approaches. The QSAR models are useful for various purposes including the prediction of activities of untested chemicals. Quantitative structure,activity relationships and other related approaches have attracted broad scientific interest, particularly in the pharmaceutical industry for drug discovery and in toxicology and environmental science for risk assessment. An assortment of new QSAR methods have been developed during the past decade, most of them focused on drug discovery. Besides advancing our fundamental knowledge of QSARs, these scientific efforts have stimulated their application in a wider range of disciplines, such as toxicology, where QSARs have not yet gained full appreciation. In this review, we attempt to summarize the status of QSAR with emphasis on illuminating the utility and limitations of QSAR technology. We will first review two-dimensional (2D) QSAR with a discussion of the availability and appropriate selection of molecular descriptors. We will then proceed to describe three-dimensional (3D) QSAR and key issues associated with this technology, then compare the relative suitability of 2D and 3D QSAR for different applications. Given the recent technological advances in biological research for rapid identification of drug targets, we mention several examples in which QSAR approaches are employed in conjunction with improved knowledge of the structure and function of the target receptor. The review will conclude by discussing statistical validation of QSAR models, a topic that has received sparse attention in recent years despite its critical importance. [source] The effect of metformin on measurements of insulin sensitivity and , cell response in 18 horses and ponies with insulin resistanceEQUINE VETERINARY JOURNAL, Issue 5 2008A. E. Durham Summary Reasons for performing study: Laminitis in equids is a very common debilitating disease, and insulin resistance (IR) and hyperinsulinaemia are increasingly recognised as important predisposing factors. Pharmacological modification of IR and hyperinsulinaemia might reduce the risk of laminitis. Hypothesis: Metformin, a drug commonly prescribed for treatment of human IR, may also decrease IR in equids. Methods: Eighteen horses and ponies with IR and recurrent laminitis were treated with 15 mg/kg bwt metformin per os q. 12 h. Each animal served as its own control by comparing pre- and post treatment proxies for IR, insulin sensitivity (IS) and pancreatic , cell function while controlling for possible dietary and managemental influences on IR. Results: Evidence of significantly improved IS and decreased pancreatic , cell secretion was found following metformin treatment. The magnitude of effect was greater at earlier resampling (6,14 days) than at later times (23,220 days). Apparent subjective clinical benefits were good but less favourable than effects on IR. Conclusions: Metformin is safe and appears to increase IS in equids. Potential relevance: Metformin may be indicated as a treatment for IR in equids. Further studies are required to define appropriate selection of subjects warranting therapy, dosing schedule and pharmacokinetics. [source] Fracture analysis of strength undermatched Al-Alloy welds in edge cracked tensile panels using FITNET procedureFATIGUE & FRACTURE OF ENGINEERING MATERIALS AND STRUCTURES, Issue 9 2008S. CICERO ABSTRACT This paper presents a methodology for the assessment of the remaining load carrying capacity of thin-walled components under tension containing highly strength undermatched welds and edge cracks. The analysis is based on the strength mismatch option of the fracture module, part of the newly developed European fitness-for-service (FFS) procedure FITNET. The mismatch option of the FITNET fracture module allows weld features such as weld tensile properties and weld geometry to be taken into account in the fracture analysis of cracked welded components. The methodology described was verified for centre cracked Al-alloy large tensile panels containing undermatched welds in Ref. [1] and hence the present work provides validation with experimental results of the single edge cracked (SEC) and double edge cracked (DEC) panels. The material used is an age-hardening aluminium alloy 6013 in T6 temper condition used in welded airframe components. The welds in the form of butt joints were produced using the CO2 laser beam welding process. The results show that by using the FITNET FFS methodology with an appropriate selection of the input parameters, safe acceptable predictions of the maximum load carrying capacity of the welded panels can be obtained. It should also be noted that one of the main difficulties that engineers encounter when applying mismatch analysis for first time is its apparent complexity. A step-by-step analysis is proposed here in order to provide guidance for this kind of assessments. [source] Perfect Bi4Ti3O12 Single-Crystal Films via Flux-Mediated Epitaxy,ADVANCED FUNCTIONAL MATERIALS, Issue 4 2006R. Takahashi Abstract Excellent crystallinity of material films and atomic control of their surface/interface, sufficient for the realization of their optimal physical properties, are technological premises for modern functional-device applications. Bi4Ti3O12 and related compounds attract much interest as highly insulating, ferroelectric materials for use in ferroelectric random-access memories. However, it has been difficult thus far for Bi4Ti3O12 films to satisfy such requirements when formed using vapor-phase epitaxy, owing to the high volatility of Bi in a vacuum. Here, we demonstrate that flux-mediated epitaxy is one of the most promising and widely applicable concepts to overcome this inevitable problem. The key point of this process is the appropriate selection of a multi-component flux system. A combinatorial approach has led to the successful discovery of the novel flux composition of Bi,Cu,O for Bi4Ti3O12 single-crystal film growth. The perfect single-crystal nature of the stoichiometric Bi4Ti3O12 film formed has been verified through its giant grain size and electric properties, equivalent to those of bulk single crystals. This demonstration has broad implications, opening up the possibility of preparing stoichiometric single-crystal oxide films via vapor-phase epitaxy, even if volatile constituents are required. [source] Percutaneous Transluminal Angioplasty of the Anomalous Circumflex ArteryJOURNAL OF INTERVENTIONAL CARDIOLOGY, Issue 1 2001DIDIER BLANCHARD M.D. The technical experience reported in the literature concerning angioplasty in patients with anomalous origin of the left circumflex artery is limited. Balloon angioplasty seems to be a favorable approach for revascularization in these vessels, and major determinants of successful angioplasty are angiographic knowledge of their course and structure, appropriate selection of guiding catheter, and the possibility of advancing the balloon into the anomalous vessel. Five consecutive patients with severe atherosclerotic lesions on the anomalous left circumflex artery who underwent coronary angioplasty of the anomalous vessel are reported. Angiographic and clinical success were achieved in three patients with balloon alone and in one with stent implantation. (J Interven Cardiol 2001;14:11,16) [source] New stage in living cationic polymerization: An array of effective Lewis acid catalysts and fast living polymerization in secondsJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 10 2007Sadahito Aoshima Abstract Our recent extensive research on Lewis acid catalysts with a weak base for the cationic polymerization of vinyl ethers led to unprecedented living reaction systems: fast living polymerization within 1,3 s; a wide choice of metal halides containing Al, Sn, Fe, Ti, Zr, Hf, Zn, Ga, In, Si, Ge, and Bi; and heterogeneously catalyzed living polymerization with Fe2O3. The use of added bases for the stabilization of the propagating carbocation and the appropriate selection of Lewis acid catalysts were crucial to the success of such new types of living polymerizations. In addition, the base-stabilized living polymerization allowed the quantitative synthesis of star-shaped polymers with a narrow molecular weight distribution via polymer-linking reactions and the precision synthesis and self-assembly of stimuli-responsive block copolymers. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1801,1813, 2007. [source] Photopolymerization of ternary thiol,ene/acrylate systems: Film and network propertiesJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 5 2007Huanyu Wei Abstract Photocurable, ternary-component mixtures of a 1:1 molar multifunctional thiol,ene (trithiol and triallyl ether) blend and a 16-functional acrylate based monomer have been photopolymerized, and the final film properties of the ternary crosslinked networks have been measured. The photopolymerization kinetics, morphology, and mechanical and physical properties of the films have been investigated with real-time infrared, atomic force microscopy, and dynamic mechanical analysis. The photopolymerization process is a combination of acrylate homopolymerization and copolymerizations of thiol with allyl ether and acrylate functionalities. The tan , peaks of the photopolymerized ternary systems are relatively narrow and tunable over a large temperature range. The morphology is characterized by a distinct phase-separated nanostructure. The photocured thiol,ene/acrylate ternary systems can be made to exhibit good mechanical properties with enhanced energy absorption at room temperature by the appropriate selection of each component concentration. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 822,829, 2007. [source] How to diagnose and treat hepatitis B virus antiviral drug resistance in the liver transplant settingLIVER TRANSPLANTATION, Issue S2 2008Anna S. F. Lok Key Points 1Hepatitis B virus variants with antiviral drug,resistant mutations and/or hepatitis B immune globulin,resistant mutations are the main cause of hepatitis B virus reinfections post,liver transplant. 2Early diagnosis of antiviral drug resistance and prompt initiation of rescue therapy are important in preventing hepatitis flares and hepatic decompensation. 3Virologic breakthrough is the first indication of antiviral drug resistance. 4Genotypic resistance testing should be performed when possible to avoid unnecessary modification of treatment in patients who do not have confirmed antiviral drug resistance and to permit appropriate selection of rescue therapy in those who have confirmed antiviral drug resistance. 5Choice of rescue therapy requires knowledge of the past history of hepatitis B virus treatments and virologic response to those treatments, patterns of mutations detected at the time of virologic breakthrough, and in vitro cross-resistance data. 6Occurrence of antiviral drug resistance can be reduced by the use of the most potent nucleos(t)ide analogue(s) with the highest genetic barrier to resistance, emphasis of medication compliance, and close monitoring of virologic response. Liver Transpl 14:S8,S14, 2008. © 2008 AASLD. [source] Maximising the fuel efficiency of engine oils: The role of tribologyLUBRICATION SCIENCE, Issue 3 2001Stefan Korcek Abstract Improvement of engine fuel efficiency is one of the most important goals of current automotive development. Maximising the contribution of engine oils to fuel efficiency is a very important part of this process. Engine friction modelling, based on fundamental tribological considerations, has shown that further engine friction improvements are possible through engine oil reformulation. This reformulation should minimise friction under hydrodynamic conditions through modification of the rheological properties of oils, and also minimise friction under mixed and boundary lubrication conditions through changes in the chemical composition of the oils. These improvements can be achieved by appropriate selection of a base oil as well as by the use of effective friction-reducing additive systems. A very important consideration in formulating these highly fuel-efficient oils is their ability to retain their fuel efficiency during the entire oil service interval. This paper describes the role of tribological research in the development and introduction of advanced fuel-efficient engine oils. [source] The management of severe Crohn's diseaseALIMENTARY PHARMACOLOGY & THERAPEUTICS, Issue 5 2001M. Parkes The treatment of severe and active Crohn's disease is currently based on immunosuppression, but also involves the management of nutrition, appropriate selection of patients for surgery, and maintenance of remission in the long term. Corticosteroids remain the drug of the first choice, particularly in the acute setting. However, there is evolving understanding of the role of other immunosuppressants and immune modifiers, as major concerns regarding side-effects and efficacy of steroids in the medium to long-term drive the search for alternatives. [source] Numerical solution of a minimax ergodic optimal control problemPROCEEDINGS IN APPLIED MATHEMATICS & MECHANICS, Issue 1 2007Aragone Laura S. In this work we consider an L, minimax ergodic optimal control problem with cumulative cost. We approximate the cost function as a limit of evolutions problems. We present the associated Hamilton-Jacobi-Bellman equation and we prove that it has a unique solution in the viscosity sense. As this HJB equation is consistent with a numerical procedure, we use this discretization to obtain a procedure for the primitive problem. For the numerical solution of the ergodic version we need a perturbation of the instantaneous cost function. We give an appropriate selection of the discretization and penalization parameters to obtain discrete solutions that converge to the optimal cost. We present numerical results. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Assessing the technological capabilities of firms: developing a policy toolR & D MANAGEMENT, Issue 3 2007Howard Rush The development of technological capabilities results from an extended learning process and external policy agents can play an important role in its development. This paper outlines trends in governmental and non-governmental policy initiatives and the use of concepts such as capability and absorptive capacity, which are positioned within generic-staged models of capability maturity. This paper describes the development of a technology capability assessment/audit tool that has been designed to help locate firms within four archetypes based upon their level of maturity on nine key dimensions of the management of technology. The tool is intended to help bridge the gap between our theoretical understanding of the principles of technology management and policy practice , allowing policy makers to design mechanisms that focus resources in areas of greatest need through the appropriate selection of policy mechanisms and the targeted design of policy. The use of this tool in field experiments is described along with the implications for policy making. [source] Temperature changes in dental pulp associated with use of power grinding equipment on equine teethAUSTRALIAN VETERINARY JOURNAL, Issue 1-2 2005GJ WILSON Objective To quantify the temperature changes in the dental pulp associated with equine dental procedures using power grinding equipment. Design A matrix experimental design with replication on the same sample was followed to allow the following independent variables to be assessed: horse age (young or old), tooth type (premolar or molar), powered grinding instrument (rotating disc or die grinder), grinding time (15 or 20 seconds) and the presence or absence of water coolant. Procedure Sound premolar and molar teeth from a 6-year-old horse and a 15-year-old horse, which had been removed postmortem, were sectioned parallel to the occlusal plane to allow placement of a miniature thermocouple at the level of the dental pulp. The maximum temperature increase, the time taken to reach this maximum and the cooling time were measured (n=10 in each study). The teeth were placed in a vice and the instrument used on the tooth as per clinical situation. Results Significant differences were recorded for horse age (P < 0.001), instrument type (P < 0.001), grinding time (P < 0.001) and presence or absence of coolant (P < 0.001). There was no significant difference for tooth type. Conclusion Thermal insult to the dental pulp from the use of power instruments poses a significant risk to the tooth. This risk can be reduced or eliminated by appropriate selection of treatment time and by the use of water irrigation as a coolant. The increased dentine thickness in older horses appears to mitigate against thermal injury from frictional heat. [source] Optimal Synthesis of Protein Purification ProcessesBIOTECHNOLOGY PROGRESS, Issue 4 2001Elsa Vásquez-Alvarez There has been an increasing interest in the development of systematic methods for the synthesis of purification steps for biotechnological products, which are often the most difficult and costly stages in a biochemical process. Chromatographic processes are extensively used in the purification of multicomponent biotechnological systems. One of the main challenges in the synthesis of purification processes is the appropriate selection and sequencing of chromatographic steps that are capable of producing the desired product at an acceptable cost and quality. This paper describes mathematical models and solution strategies based on mixed integer linear programming (MILP) for the synthesis of multistep purification processes. First, an optimization model is proposed that uses physicochemical data on a protein mixture, which contains the desired product, to select a sequence of operations with the minimum number of steps from a set of candidate chromatographic techniques that must achieve a specified purity level. Since several sequences that have the minimum number of steps may satisfy the purity level, it is possible to obtain the one that maximizes final purity. Then, a second model that may use the total number of steps obtained in the first model generates a solution with the maximum purity of the product. Whenever the sequence does not affect the final purity or more generally does not impact the objective function, alternative models that are of smaller size are developed for the optimal selection of steps. The models are tested in several examples, containing up to 13 contaminants and a set of 22 candidate high-resolution steps, generating sequences of six operations, and are compared to the current synthesis approaches. [source] Magnifying Superlenses and other Applications of Plasmonic Metamaterials in Microscopy and SensingCHEMPHYSCHEM, Issue 4 2009Igor I. Smolyaninov Dr. Abstract Every last detail: New advances in the construction of metamaterials enable the creation of artificial optical media, whose use in microscopy can provide resolution that is not determined by the conventional diffraction limit. The picture shows a superposition of an AFM image of a plasmonic metamaterial onto the corresponding optical image obtained using a conventional optical microscope. Over the past century, the resolution of conventional optical microscopes, which rely on optical waves that propagate into the far field, has been limited because of diffraction to a value of the order of a half-wavelength (,0/2) of the light used. Although immersion microscopes have slightly improved resolution, of the order of ,0/2n, the increased resolution is limited by the small range of refractive indices n of available transparent materials. However, now we are experiencing a quick demolition of the diffraction limit in optical microscopy. In the last few years, numerous nonlinear optical microscopy techniques based on photoswitching and saturation of fluorescence have demonstrated far-field resolution of 20 to 30 nm. In a parallel development, recent progress in metamaterials has demonstrated that artificial optical media can be created, whose use in microscopy can provide resolution that is not determined by the conventional diffraction limit. The resolution of linear immersion microscopes based on such metamaterials is only limited by losses, which can be minimized by appropriate selection of the constituents of the metamaterials used and by the wavelength(s) used for imaging. It is also feasible to compensate for losses by adding gain to the structure. Thus, optical microscopy is quickly moving towards resolution of around 10 nm, which should bring about numerous revolutionary advances in lithography and imaging. [source] | ||||||||||||||||||||||