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Relevant Examples (relevant + example)

Distribution by Scientific Domains

Chemistry	63%

Selected Abstracts

Basic pharmacology relevant to drug abuse assessment: tramadol as example

JOURNAL OF CLINICAL PHARMACY & THERAPEUTICS, Issue 2 2008
R. B. Raffa PhD
Summary Tramadol is a centrally acting analgesic in widespread use throughout the world. Although there is extensive preclinical, clinical, post-marketing and epidemiological data indicating relatively low , but not zero , abuse/dependence, questions continue to arise about its abuse potential and appropriate regulatory classification. This article considers these questions from the point of view of the basic pharmacology of tramadol. There is nothing unique about tramadol in this regard, but its multimodal mechanism of action, pharmacologically active enantiomers, and active metabolite make it a particularly instructive and relevant example. [source]

Neutralization theory and the denial of risk: some evidence from cannabis use among French adolescents*

THE BRITISH JOURNAL OF SOCIOLOGY, Issue 1 2003
Patrick Peretti-Watel
ABSTRACT In contemporary societies, risk culture and risk profiling lead to the stigmatization of unhealthy behaviours as ,risky'. Risk denial theory refers to a cognitive way to deal with risky behaviours and can be considered as an updated variant of Sykes and Matza's neutralization theory. People neutralize the ,risky' label using specific techniques that must be added to those previously enlisted by Sykes and Matza. This paper introduces and discusses three techniques of risk denial: scapegoating, self-confidence and comparison between risks. As it is usually defined and studied as a ,risky behaviour', cannabis use provides a relevant example to illustrate these types of risk denial, thanks to various ethnographic studies (including Becker's seminal work on marijuana smokers) and quantitative French data from the 1999 European School Survey on Alcohol and Other Drugs (ESPAD). In order to deny the ,risky' label, cannabis users scapegoat ,hard drugs' users, they emphasize their own ability to control their consumption personally, or they compare cannabis and alcohol risks. The paper concludes with suggestions for further analyses of risk denial. [source]

The Synthesis and Assembly of Polymeric Microparticles Using Microfluidics

ADVANCED MATERIALS, Issue 41 2009
Dhananjay Dendukuri
Abstract The controlled synthesis of micrometer-sized polymeric particles bearing features such as nonspherical shapes and spatially segregated chemical properties is becoming increasingly important. Such particles can enable fundamental studies on self-assembly and suspension rheology, as well as be used in applications ranging from medical diagnostics to photonic devices. Microfluidics has recently emerged as a very promising route to the synthesis of such polymeric particles, providing fine control over particle shape, size, chemical anisotropy, porosity, and core/shell structure. This progress report summarizes microfluidic approaches to particle synthesis using both droplet- and flow-lithography-based methods, as well as particle assembly in microfluidic devices. The particles formed are classified according to their morphology, chemical anisotropy, and internal structure, and relevant examples are provided to illustrate each of these approaches. Emerging applications of the complex particles formed using these techniques and the outlook for such processes are discussed. [source]

Three-dimensional incompressible flow calculations using the characteristic based split (CBS) scheme

INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 11 2004
P. Nithiarasu
Abstract In this paper, the characteristic based split scheme is employed for the solution of three-dimensional incompressible viscous flow problems on unstructured meshes. Many algorithm related issues are discussed. Fully explicit and semiimplicit forms of the scheme are explained and employed in the calculation of both isothermal and nonisothermal incompressible flows simulation. The extension of the scheme to porous medium flows is also demonstrated with relevant examples. Copyright © 2004 John Wiley & Sons, Ltd. [source]

PTR-TOF-MS and data-mining methods for rapid characterisation of agro-industrial samples: influence of milk storage conditions on the volatile compounds profile of Trentingrana cheese,

JOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 9 2010
Alessandra Fabris
Abstract Proton transfer reaction-mass spectrometry (PTR-MS), a direct injection mass spectrometric technique based on an efficient implementation of chemical ionisation, allows for fast and high-sensitivity monitoring of volatile organic compounds (VOCs). The first implementations of PTR-MS, based on quadrupole mass analyzers (PTR-Quad-MS), provided only the nominal mass of the ions measured and thus little chemical information. To partially overcome these limitations and improve the analytical capability of this technique, the coupling of proton transfer reaction ionisation with a time-of-flight mass analyser has been recently realised and commercialised (PTR-TOF-MS). Here we discuss the very first application of this new instrument to agro-industrial problems and dairy science in particular. As a case study, we show here that the rapid PTR-TOF-MS fingerprinting coupled with data-mining methods can quickly verify whether the storage condition of the milk affects the final quality of cheese and we provide relevant examples of better compound identification in comparison with the previous PTR-MS implementations. In particular, ,Trentingrana' cheese produced by four different procedures for milk storage are compared both in the case of winter and summer production. It is indeed possible to set classification models with low prediction errors and to identify the chemical formula of the ion peaks used for classification, providing evidence of the role that this novel spectrometric technique can play for fundamental and applied agro-industrial themes. Copyright © 2010 John Wiley & Sons, Ltd. [source]

Wavelet-based adaptive grid method for the resolution of nonlinear PDEs

AICHE JOURNAL, Issue 4 2002
Paulo Cruz
Theoretical modeling of dynamic processes in chemical engineering often implies the numeric solution of one or more partial differential equations. The complexity of such problems is increased when the solutions exhibit sharp moving fronts. A new numerical method is established, based on interpolating wavelets, that dynamically adapts the collocation grid so that higher resolution is automatically attributed to domain regions where sharp features are present. The effectiveness of the method is demonstrated with some relevant examples in a chemical engineering context. [source]

The role of ASTM E27 methods in hazard assessment part II: Flammability and ignitability

PROCESS SAFETY PROGRESS, Issue 1 2005
Laurence G. Britton
Accurate flammability and ignitability data for chemicals form the cornerstone of procedures used to assess the hazards associated with commercial chemical production and use. Since 1967 the ASTM E27 Committee on the Hazard Potential of Chemicals has issued numerous, widely used consensus standards dealing with diverse testing and predictive procedures used to obtain relevant chemical hazard properties. The decision to issue a standard rests solely with the membership, which consists of representatives from industry, testing laboratories, consulting firms, government, academia, and instrument suppliers. Consequently, the procedures are automatically relevant, timely, and widely applicable. The purpose of this paper is to highlight some of the widely used standards, complemented with hypothetical but relevant examples describing the testing strategy, interpretation, and application of the results. A further goal of this paper is to encourage participation in the consensus standards development process. The paper is published in two parts. The first part (in the preceding issue of Process Safety Progress) dealt with the E27 standards pertaining to thermodynamics, thermal stability, and chemical compatibility. The second part, published here, focuses on the flammability, ignitability, and explosibility of fuel and air mixtures. © 2005 American Institute of Chemical Engineers Process Saf Prog, 2005 [source]

The active site of hydroxynitrile lyase from Prunus amygdalus: Modeling studies provide new insights into the mechanism of cyanogenesis

PROTEIN SCIENCE, Issue 2 2002
Ingrid Dreveny
Abstract The FAD-dependent hydroxynitrile lyase from almond (Prunus amygdalus, PaHNL) catalyzes the cleavage of R -mandelonitrile into benzaldehyde and hydrocyanic acid. Catalysis of the reverse reaction,the enantiospecific formation of ,-hydroxynitriles,is now widely utilized in organic syntheses as one of the few industrially relevant examples of enzyme-mediated C,C bond formation. Starting from the recently determined X-ray crystal structure, systematic docking calculations with the natural substrate were used to locate the active site of the enzyme and to identify amino acid residues involved in substrate binding and catalysis. Analysis of the modeled substrate complexes supports an enzymatic mechanism that includes the flavin cofactor as a mere "spectator" of the reaction and relies on general acid/base catalysis by the conserved His-497. Stabilization of the negative charge of the cyanide ion is accomplished by a pronounced positive electrostatic potential at the binding site. PaHNL activity requires the FAD cofactor to be bound in its oxidized form, and calculations of the pKa of enzyme-bound HCN showed that the observed inactivation upon cofactor reduction is largely caused by the reversal of the electrostatic potential within the active site. The suggested mechanism closely resembles the one proposed for the FAD-independent, and structurally unrelated HNL from Hevea brasiliensis. Although the actual amino acid residues involved in the catalytic cycle are completely different in the two enzymes, a common motif for the mechanism of cyanogenesis (general acid/base catalysis plus electrostatic stabilization of the cyanide ion) becomes evident. [source]

The Biochemistry of Drug Metabolism , An Introduction

CHEMISTRY & BIODIVERSITY, Issue 5 2009

Abstract This review continues a general presentation of the metabolism of drugs and other xenobiotics begun in five recent issues of Chemistry & Biodiversity. The present Part is dedicated to the pharmacological and toxicological consequences of drug and xenobiotic metabolism. In other words, the key concepts here are activation vs. deactivation, toxification vs. detoxification, and their interplay. These concepts are illustrated with a number of medicinally, toxicologically, and environmentally relevant examples. But, far from being concerned only with individual cases, the review is based on broad classifications, global rationalizations, and synthetic hypotheses. [source]

The Biochemistry of Drug Metabolism , An Introduction

CHEMISTRY & BIODIVERSITY, Issue 11 2008

Abstract This review continues a general presentation of the metabolism of drugs and other xenobiotics begun in three recent issues of Chemistry & Biodiversity. The present Part is dedicated to reactions of conjugation, namely methylation, sulfonation, and phosphorylation, glucuronidation and other glycosidations, acetylation and other acylations, the formation and fate of coenzyme A conjugates, glutathione conjugation, and the reaction of amines with carbonyl compounds. It presents the many transferases involved, their nomenclature, relevant biochemical properties, catalytic mechanisms, and the reactions they catalyze. Nonenzymatic reactions, mainly of glutathione conjugation, also receive due attention. A number of medicinally, environmentally, and toxicologically relevant examples are presented and discussed. [source]

The Biochemistry of Drug Metabolism , An Introduction

CHEMISTRY & BIODIVERSITY, Issue 3 2007

Abstract This review continues a general presentation of the metabolism of drugs and other xenobiotics started in a recent issue of Chemistry & Biodiversity. This Part,2 presents the numerous oxidoreductases involved, their nomenclature, relevant biochemical properties, catalytic mechanisms, and the very diverse reactions they catalyze. Many medicinally, environmentally, and toxicologically relevant examples are presented and discussed. Cytochromes P450 occupy a majority of the pages of Part,2, but a large number of relevant oxidoreductases are also considered, e.g., flavin-containing monooxygenases, amine oxidases, molybdenum hydroxylases, peroxidases, and the innumerable dehydrogenases/reductases. [source]