bluuebunny/crossref_metadata_2025 huggingface dataset:
Mice lacking cyclin‐dependent kinase inhibitor p19Ink4d show strain‐specific effects on male reproduction
Authors: Buchold Gregory M. , Magyar Patricia L. , O'Brien Deborah A.
Published: March 2007

p19Ink4d is a member of the INK4 family of cyclin‐dependent kinase inhibitors, which are important negative regulators of the G1‐phase cyclin‐dependent kinases CDK4 and CDK6. On a mixed C57BL/6 × 129P2/OlaHsd background, mice deficient for p19Ink4d exhibited defects in male reproductive function including testicular atrophy, alteration in serum follicle stimulating hormone, qualitative increase in germ cell apoptosis, and delayed kinetics of meiotic prophase markers (Zindy et al., 2001. Mol Cell Biol 21:3244–3255; Zindy et al., 2000. Mol Cell Biol 20:372–378). In this study, a quantitative assessment of these aspects of reproductive capacity demonstrated relatively mild deficits in p19Ink4d−/− males compared to controls. These effects did not dramatically worsen in older males although some seminiferous tubule defects were observed. Following marker‐assisted backcrossing into the C57BL/6 background, p19Ink4d−/− males did not display defects in testis weights, sperm numbers, serum FSH, germ cell apoptosis, or kinetics of selected meiotic prophase markers. These studies indicate that a reduction in Ink4 family function by the loss of p19Ink4d is sufficient to induce mild reproductive defects in male mice with a mixed genetic background, but not in the C57BL/6 genetic background. Mol. Reprod. Dev. 74: 1008–1020, 2007. © 2007 Wiley‐Liss, Inc.
Constrained minimax optimization of continuous search efforts for the detection of a stationary target
Authors: Dambreville Frédéric , Le Cadre Jean‐Pierre
Published: March 2007

Analytical resolution of search theory problems, as formalized by B.O. Koopman, may be applied with some model extension to various resource management issues. However, a fundamental prerequisite is the knowledge of the prior target density. Though this assumption has the definite advantage of simplicity, its drawback is clearly that target reactivity is not taken into account. As a preliminary step towards reactive target study stands the problem of resource planning under a min–max game context. This paper is related to Nakai's work about the game planning of resources for the detection of a stationary target. However, this initial problem is extended by adding new and more general constraints, allowing a more realistic modeling of the target and searcher behaviors. © 2007 Wiley Periodicals, Inc. Naval Research Logistics, 2007
Buckling of simply‐supported skew plates
Authors: Edwardes R. J. , Kabaila A. P.
Published: March 2007

The difficulties associated with the solution of the skew plate buckling problem are described, and the work of other writers is summarized.

By solving a numerical example, the relative advantages of two proposed refinements to the finite element displacement method are demonstrated: A technique of boundary condition relaxation appears justified and gives favourable results compared with conventional boundary condition specification. A mesh grading technique, which is simple to apply, results in a marked improvement in convergence to a solution.
Finite elements of C1‐class on a tetrahedron
Authors: Délèze M. , Goël J.‐J. , Meyenhofer B.
Published: March 2007

This paper describes two finite elements of C1‐class defined on a tetrahedron. In order to define these elements we give the corresponding function spaces in explicit form.
On suitable formulations of the method of modal analysis for numerical calculations
Authors: Gobmann E. , Krings W. , Waller H.
Published: March 2007

The method of modal analysis is a method widely used in structural analysis of linear systems. After a short introduction two step by step formulations for modal calculations are discussed. One of them is of more theoretical interest, the other is recommended for practical calculations for multi‐degree‐of‐freedom systems because it is efficient in computing time. The first is formulated for the whole system the latter for each mode. Likewise a combination of the method of modal analysis and the LAPLACE transformation is established. The numerical calculation of the LAPLACE transformation is done by using the algorithm of the Fast FOURIER transformation. The advantages of the different formulations for numerical calculations are discussed.
Solution of fixed cost trans‐shipment problems by a branch and bound method
Authors: Hindi K. S. , Brameller A. , Hamam K. M.
Published: March 2007

Varied problems in the fields of operation, scheduling, allocation and design in power systems analysis can be formulated as fixed cost trans‐shipment problems. This paper indicates possible areas of application of such formulations, and by exploiting specific characteristics of certain power systems problems presents an efficient branch and bound method for solving them.
Finite element method for spectral modelling of tides
Authors: le Provost Christian , Poncet Alain
Published: March 2007

A spectral method for modelling of tides is proposed and applied to the calculation of the M2 component of the tide in the English Channel. The classical non‐linear hyperbolic problem of long wave propagation in shallow waters is transformed into a sequence of elliptic problems by looking at a multiperiodic solution the frequencies of which are previously known. The method is based upon a perturbation technique, but the principal difficulties arise from the non‐analytical form of the quadratic friction term: the main conclusions of the corresponding study only are given here, because the purpose of this paper is to present a practical application of the method to the calculation of a tidal component by the finite element method. The variational formulation of the problem is presented, and the finite element package used is described. Some results are given for the M2 tide in the English Channel: cotidal maps and current fields.
A displacement scheme with drilling degrees of freedom for plane elements
Authors: Cannarozzi Agostino A. , Cannarozzi Mario
Published: March 2007

A scheme of boundary displacements with drilling degrees of freedom for plane elements is presented. The scheme is free from zero displacement modes and allows the development of hybrid finite elements with vertex and mid‐side nodes, each node including a drilling degree of freedom besides the translational ones. Four quadrilateral isoparametric hybrid stress elements are implemented, and numerical results for some current test problems are given.
A pseudo‐fully stressed design approach for optimum design of steel frames
Authors: Al‐Salloum Yousef A.
Published: March 2007

An iterative approach based on the fully‐stressed design concept employing scaling to find an efficient search path to the optimum design is developed for statically indeterminate elastic frames subjected to behavioural constraints on member stresses and nodal displacements, and side constraints on member sizes. In this approach the fully stressed solution, which recognizes only the stress constraints, is scaled to the boundary of the feasible design region by employing the other constraints on the structure. The inactive constraints in an iteration are identified by the Kuhn‐Tucker conditions. The computed stresses of the inactive constraints, for the time being, are considered to be the allowable values in order to develop a pseudo‐fully stressed solution with a new set of allowable stresses. Convergence takes places when the normalized change in the value of the objective function between the scaled and unsealed pseudo‐fully stressed designs is less than a specified tolerance. The method employs the established relationships between sectional area, section modulus and moment of inertia of W‐shapes to express the objective and constraint functions in terms of one design variable for each member. The efficiency and accuracy of the method in optimization of structural steel frames is demonstrated by sample problems designed for stress, displacement and minimum size constraints. The algorithm is verified against published results.
An incremental formulation for the prediction of two‐dimensional fatigue crack growth with curved paths
Authors: Kim Ki‐Seok , Lee Hae Sung
Published: March 2007

This paper presents a new incremental formulation for predicting the curved growth paths of two‐dimensional fatigue cracks. The displacement and traction boundary integral equations (BIEs) are employed to calculate responses of a linear elastic cracked body. The Paris law and the principle of local symmetry are adopted for defining the growth rate and direction of a fatigue crack, respectively. The three governing equations, i.e. the BIEs, the Paris law and the local symmetry condition, are non‐linear with respect to the crack growth path and unknowns on the boundary. Iterative forms of three governing equations are derived to solve problems of the fatigue crack growth by the Newton–Raphson method. The incremental crack path is modelled as a parabola defined by the crack‐tip position, and the trapezoidal rule is employed to integrate the Paris law. The validity of the proposed method is demonstrated by two numerical examples of plates with an edge crack. Copyright © 2007 John Wiley & Sons, Ltd.
Numerical comparison of some Hessian recovery techniques
Authors: Vallet M.‐G. , Manole C.‐M. , Dompierre J. , Dufour S. , Guibault F.
Published: March 2007

Derivative recovery techniques are used in a posteriori error indicators to drive mesh adaptation. Their behaviour in the core of the computational domain and on boundaries constitutes an important efficiency factor for a subsequent mesh adaptation process. A methodology to compare recovery techniques for second‐order derivatives from a piecewise linear approximation is presented in this paper. A systematic approach to measuring the performance of recovery techniques using analytical functions interpolated on a series of meshes is proposed. The asymptotic behaviour of some recently published recovery techniques, as well as new ones, is numerically assessed on various type of meshes. Recommendations are done on the choice of a recovery technique. Copyright © 2007 John Wiley & Sons, Ltd.
Enhancing care in older people with type 2 diabetes
Authors: Sinclair Alan J
Published: March 2007

Managing diabetes care in the elderly population is challenging because of complex co‐morbid medical issues and the generally lower functional status of older patients. Diabetes is an independent risk factor for admission into a care home and the prevalence of diabetes in this setting is high. A number of key issues relating to functional ability provide the basis of difficult management scenarios, e.g. falls, cognitive dysfunction, depressive illness, and a high prevalence of cardiovascular disease. This article presents a patient profile to illustrate the issues that are specific to the care of older people with diabetes and highlights the importance of clinical guidelines produced by the European Diabetes Working Party for Older People. These have been designed to give guidance for best clinical practice across all care settings. Copyright © 2007 John Wiley & Sons.
Adhesion of polyethylene to high energy substrates
Authors: Bright K. , Malpass B. W. , Packham D. E.
Published: March 2007

The paper describes results which have been used to establish salient features in the adhesion of polyethylene to high energy substrates. Generally, to obtain a good bond, conditions must favour oxidation of the polymer. However, with very porous substrates, good adhesion is obtainable in the absence of polymer oxidation.
Statistics of stiff chain molecules: II. The mean square radius of gyration of semiflexible helices
Authors: Burchard Walther
Published: March 2007

A simple chain model for semiflexible helices, defined by the pitch height, the number of residues per turn and a certain flexibility, is suggested. In this model, the coordinate system is chosen such that, in the limit of a rigid and perfect helix, the z‐axis coincides with the helix axis. Owing to its flexibility, the moving helix axis is allowed to perform random fluctuations in the x and y directions within certain limits. Analytic expressions are derived for the mean square end‐to‐end distance and for the mean square radius of gyration as functions of the degree of polymerisation through the use of generating functions. There appear three essential roots of a cubic equation, the largest of which is determined by the flexibility of the helix.
Statistics of stiff chain molecules: III. Chain length dependence of the mean square radius of gyration of cellulose‐ and amylose‐tricarbanilates
Authors: Burchard Walther
Published: March 2007

The unperturbed mean square radii of gyration of the two isomeric chains of cellulose‐ and of amylose‐tricarbanilates were measured over a wide range of degree of polymerisation. Both chains exhibit pronounced deviations from the Gaussian statistical conformation because of a remarkable chain stiffness. Four model calculations were performed to interpret the data: (a) the freely rotating chain model; (b) a chain with a symmetric potential of the hindered rotation around ϕ = ϕ = 0; (c) a chain with a hindrance potential symmetric around ϕ = ϕ* (d) an approximate model of (c). Because of the complicated ring conformation, the glucose units have to be approximated by a two‐bond unit, or by a one‐bond unit with variable valence angle. Model (d) differs from model (c) by the assumption that the valence angle of stiff chains is constant. Cellulose‐tricarbanilate could be reasonably interpreted by model (b), while for amylose‐tricarbanilate, helical conformations had to be taken into account. Eight helix conformations, discussed in the literature, were calculated on the basis of models (c) and (d). The experimental data could best be fitted by a helix of 4 residues per turn, a pitch height of 10.4 Å and a remarkable chain stiffness, The conception of chain stiffness is discussed, and it is shown that the chain extension or the chain expansion are not suitable stiffness parameters, while a generalised persistence length and a fluctuation parameter cos x, defined in the paper, are appropriate to describe the stiffness. The approximate model (d) appeared practically equivalent to the more elaborate model (c) for all helices considered.
Oxidative degradation of a polyimide film: I. Initial studies
Authors: Dine‐Hart R. A. , Parker D. B. V. , Wright W. W.
Published: March 2007

High molecular weight poly‐N,N′‐(4,4′‐diphenylether)pyromellitimide film was prepared from pyromellitic dianhydride and 4,4′‐diaminodiphenylether and the oxidative degradation at 400°C was studied by weight loss measurements, infrared spectrometry and saponification experiments. The results indicated the rapid development of crosslinks between the polyimide chains.
Oxidative degradation of a polyimide film: III. Kinetic studies
Authors: Dine‐Hart R. A. , Parker D. B. V. , Wright W. W.
Published: March 2007

The amounts of unchanged pyromellitimide and diphenylether components in a poly‐N,N′‐(4,4′‐diphenyl‐ether)pyromellitimide film were determined as a function of the time of oxidation at 400°C. Coupling of the diphenylether portion of the chain to give complex aromatic structures occurred at a faster rate than destruction of the pyromellitimide ring. Both these processes were much faster than the overall rate of oxidation as measured by weight loss.
Ionic conduction in polymer films: IV. The effect of pigmentation with iron oxide
Authors: Mayne J. E. O. , Scantlebury J. D.
Published: March 2007

Ionic conduction in continuous polymer films is of two types. Inverse conduction occurs when the resistance of the film runs counter to, and direct conduction when the resistance follows, that of the external solution. The effect of pigmentation with iron oxide on the type of conduction has been examined in the case of films prepared from a pentaerythritol alkyd, a phenolformaldehyde tung oil and an epoxypolyamide varnish. It was found that upon progressive pigmentation the percentage samples showing direct conduction rose and then fell, furthermore no change in glass transition temperature was observed. It is suggested that this may be due to the segregation of low molecular weight material around the pigment particles thus screening them from the main bulk of the polymer.
‘Monte carlo’ computer simulation of chain molecules: II. The limiting distribution of end‐to‐end distance for two‐dimensional excluded‐volume chains
Authors: Lal M.
Published: March 2007

A computer technique for simulating configurational behaviour of chains, developed previously, was used to study the nature of the distribution of the magnitude of end‐to‐end vectors of excluded‐volume chains constrained to two dimensions. The study revealed that the above distribution in the limit of infinite chain length deviates greatly from Gaussian behaviour and that the deviation is much greater than for three‐dimensional chains. The probability distribution function A exp (—αR5.8) was derived.
Alkarenesulphonates from Fischer‐Tropsch waxes and their evaluation as anti‐stresscracking agents in polyethylene
Authors: Dressler Flemming , Meoni Massimo
Published: March 2007

Fischer‐Tropsch waxes were converted into alkarenesulphonates by successive chlorination, phenylation and sulphonation. The sulphonates showed high efficacy as anti‐stresscracking agents in low‐density polyethylene.
The preparation and characterisation of polymer latices formed in the absence of surface active agents
Authors: Goodwin J. W. , Hearn J. , Ho C. C. , Ottewill R. H.
Published: March 2007

Methods have been devised for the formation of monodisperse polystyrene latices in the absence of added surface active agents. The particles are stabilised, as a colloidal dispersion, by surface groupings which are an integral part of the particle and are not removed by dialysis. By suitable variation of the ionic strength of the aqueous phase, the initiator concentration and the polymerisation temperature, the final particle size obtained in single‐stage reactions was varied between c. 0.15 and 1.0 μm. The coefficient of variation on particle diameters was usually less than 5%. The ionic strength of the aqueous phase was found to play an important part in determining particle size; this was explained in terms of a limited coagulation process occurring at the stage involving the nucleation of polymer particles. Conductometric titration experiments revealed the presence of sulphate, carboxyl and hydroxyl groups on the particle surfaces. Molecular weight determination of the polystyrene formed showed that this was lower than that formed in conventional emulsion polymerisation.
Copolymerisation reactions of acenaphthylene at high pressures
Authors: Romani M. Nazir , Weale Kenneth E.
Published: March 2007

Radical copolymerisations in the systems acenaphthylene/methyl methacrylate, and acenaphthylene/maleic anhydride, have been investigated at 60 °C, and at pressures up to 4 kbars. The effect of pressure on the rate of polymerisation of acenaphthylene in tetrachloroethylene has also been measured. The pressure acceleration of the reactions varies with the monomer ratio in the first system, but is invariant in the copolymerisation with maleic anhydride, in which an alternating copolymer is formed. The reactivity ratio of ACN is significantly lower in both systems at high pressures. The results are related to a degradative transfer reaction with acenaphthylene monomer.
Use of polyvinyl alcohol in the manufacture of polyvinyl chloride
Authors: Shiraishi Makoto , Toyoshima Kentaro
Published: March 2007

The stabiliser used in the suspension polymerisation of vinylchloride influences greatly the quality of the resulting polyvinyl chloride, in particle size and distribution, and the absorption rate of plasticiser, etc.

The relationship between the manufacturing conditions of polyvinylalcohol (PV‐OH) and its dispersing power was studied using vinyl acetate and trichloro‐ethylene in place of vinyl chloride monomer.

It was found that the dispersing power increased with greater the blocklike distribution of the intramolecular residual acetyl group and uneven distribution of the intermolecular residual acetyl groups of PV‐OH.

When such PV‐OH was used in suspension polymerisation of vinyl‐chloride monomer, good quality polyvinylchloride was obtained. PV‐OH with such characteristics is preferable as stabiliser for the suspension polymerisation of vinyl chloride monomer.
Monitoring ultraviolet radiation with polyvinylchloride
Authors: Martin Keith G.
Published: March 2007

The photo‐oxidation of unstabilised polyvinylchloride has been shown to be sensitive only to the ultraviolet region of xenon‐arc radiation, and the rate of oxidation as determined by an infrared spectrophotometer is approximately linear with radiation intensity. Since both spectrum and intensity of the xenon arc closely simulate terrestrial solar radiation, PVC has been examined as a simple monitor of ultraviolet radiation for use in characterising outdoor sites at which the durability of building materials is assessed. PVC films have been exposed at London, Melbourne, and Pretoria and the extent of oxidation compared with solar radiation recorded at the sites; in the case of Melbourne the extent was also compared with ultraviolet radiation.
The low temperature infrared spectrum of polyvinyl acetate
Authors: Haken John K. , Werner Ronald L.
Published: March 2007

The infrared spectrum of polyvinyl acetate is considered at liquid nitrogen temperature where an increased intensity of many bands is apparent, the increases being greatest with bands associated with the polymer chain.
The homogeneous nucleation of polymer colloids
Authors: Fitch Robert M.
Published: March 2007

A theory of particle formation based on a model involving initiation of free radicals in the continuous medium and self‐nucleation or particle capture is proposed. Expressions for determining the number of particles are presented together with a consideration of limiting cases.
Dibasic lead phosphite as a stabiliser against the natural weathering of plasticised PVC
Authors: Pearson Derek , Morley John
Published: March 2007

Dibasic lead phosphite is known to be a stabiliser for plasticised PVC against weathering. The stabilisation mechanism, however, is not known and could be due to absorption of u.v. radiation by the dibasic lead phosphite, or to an antioxidant action.

It is suggested that the mechanism, in fact, depends upon an antioxidant action against the harmful effect of atmospheric oxygen absorbed during the test, and also that a similar effect occurs during thermal degradation of the PVC in free air. This beneficial effect is due to the presence of the phosphite grouping, but it is also necessary to have sufficient basic lead present to remove chlorine ions or radicals in the form of lead chloride. It has been found that equivalent molecular amounts of dibasic lead phosphite and normal lead phosphite are equally efficient in the presence of basic lead sulphate compounds.

An interesting discovery is that the weather conditions during the early stages of an exposure test may be more important than the total radiation received by the test piece at a later date. The conditions in the early stages of a test influence the manner in which the basic lead stabiliser removes the harmful chlorine ions or radicals liberated from the polymer. Mild conditions allow sufficient time for lead to diffuse through the plastic to the surface region where it reacts to form a precipitate of lead chloride in the form of needle like crystals. Harsher conditions result in the basic lead stabiliser particles themselves absorbing the chlorine ions or radicals to form lead chlorine in situ.

Tetrabasic lead sulphate improves the stability of the PVC by absorbing some of the harmful u.v. radiation with the result that the diffusion mechanism is favoured even under severe conditions.
Transverse properties of three‐phase composites comprising continuous glass fibre, glass microspheres, and epoxy resin
Authors: Marom Gad , Stanford John L. , White Eric F. T.
Published: March 2007

Some transverse mechanical properties of composites comprising uniaxially aligned continuous glass fibres embedded in a glass microsphere‐reinforced expoxy resin matrix have been determined from three‐point bending experiments.

For a constant fibre volume fraction, the transverse modulus, strength, fracture surface energy for crack initiation and work of fracture are investigated as a function of microsphere content and compared with the equivalent two‐phase composites without beads.

Modification of composite transverse properties are attributed to corresponding changes in matrix properties and comparisons are made with boundary expressions established for two‐phase particulate systems. The effects of voids, microsphere size and surface treatment on the properties are also examined.
Particulate reinforcement of polyacrylate elastomers III. Swelling measurements
Authors: Blackley David C. , Sheikh Majid W.
Published: March 2007

This paper presents and discusses results which have been obtained for the swelling in chlorobenzene of crosslinked polyethylacrylates containing various amounts of microscopic glass beads. The adhesion between the glass beads and the elastomer matrix was varied by subjecting the beads to different surface treatments. The swelling behaviour has been found to correlate very closely with the extent of adhesion as judged by peel force measurements and tensile stress‐strain properties reported previously. In the case of beads showing pronounced adhesion to the matrix, restrictions on swelling have been interpreted in terms of an apparent enhancement of crosslink density by the reactive beads.
Latent trait models for assessing multirater multiattribute agreement
Authors: Zhou Zheng , Xin Tao
Published: April 2007

The traditional kappa statistic in assessing interrater agreement is not adequate when multiraters and multiattributes are involved. In this article, latent trait models are proposed to assess the multirater multiattribute (MRMA) agreement. Data from the Third International Mathematics and Science Studies (TIMSS) are used to illustrate the application of the latent trait models. Results showed that among four possible latent trait models, the correlated uniqueness model had the best fit to assess the MRMA agreement. Furthermore, in coding a set of different attributes, the coding accuracy within the same rater may differ across attributes. Likewise, when different raters rate the same attribute, the accuracy in rating varies among the raters. Thus, the latent models provide us with a more refined and accurate assessment of interrater agreement. The application of the latent trait models is important in school psychology research and intervention because accurate assessment of children's functioning is fundamental in designing effective intervention strategies. © 2007 Wiley Periodicals, Inc. Psychol Schs 44: 515–525, 2007.
Analyzing change in school psychology research
Authors: Kulikowich Jonna M. , Edwards Maeghan N.
Published: April 2007

We look at three common research scenarios, one in the behavioral domain (i.e., disruptive behaviors) one in the cognitive domain (i.e., academic achievement), and one in the affective domain (i.e., anxiety and stress) for which school psychologists are asked to address important questions related to change. We list measurement and statistical considerations across these scenarios, including whether variables are manifest or latent, the scales of measurement, the dimensionality of measures, the units of analysis, the sample size, and the frequency or duration of time, given the primary nature of the variables under study. We suggest that researchers carefully consider whether assumptions can be met employing classical general linear models, or whether contemporary alternatives, such as hierarchical linear modeling (HLM), should be recommended for the more appropriate handling of data. © 2007 Wiley Periodicals, Inc. Psychol Schs 44: 535–542, 2007.
Comments on ‘an improved characteristic molecular volume parameter for linear solvation energy relationships of acyclic alkanes’
Authors: Mintz Christina , Acree William E.
Published: March 2007

The characteristic molecular volume parameter suggested by Palatinus et al. [J. Phys. Org. Chem., DOI: 10.1002/poc.1065] is used in predicting the enthalpies of vaporization of 41 branched acyclic alkanes. Calculations provide one additional example illustrating where the use of the Palatinus et al. characteristic molecular volume parameter over the Abraham‐McGowan molecular volume parameter led to a better mathematical description/description of thermodynamic and/or physical property data for branched acyclic alkanes. Copyright © 2007 John Wiley & Sons, Ltd.
Conservation of metal‐coordinating residues
Authors: Kasampalidis Ioannis N. , Pitas Ioannis , Lyroudia Kleoniki
Published: March 2007

As a result of rapid advances in genome sequencing, the pace of discovery of new protein sequences has surpassed that of structure and function determination by orders of magnitude. This is also true for metal‐binding proteins, that is, proteins that bind one or more metal atoms necessary for their biological function. While metal binding site geometry and composition have been extensively studied, no large scale investigation of metal‐coordinating residue conservation has been pursued so far. In pursuing this analysis, we were able to corroborate anecdotal evidence that certain residues are preferred to others for binding to certain metals. The conservation of most metal‐coordinating residues is correlated with residue preference in a statistically significant manner. Additionally, we also established a statistically significant difference in conservation between metal‐coordinating and noncoordinating residues. These results could be useful for providing better insight to functional importance of metal‐coordinating residues, possibly aiding metal binding site prediction and design, metal‐protein complex structure prediction, drug discovery, as well as model fitting to electron‐density maps produced by X‐ray crystallography. Proteins 2007. © 2007 Wiley‐Liss, Inc.
Characterization of Salmonella typhimurium YegS, a putative lipid kinase homologous to eukaryotic sphingosine and diacylglycerol kinases
Authors: Nichols Charlie E. , Lamb Heather K. , Lockyer Mike , Charles Ian G. , Pyne Susan , Hawkins Alastair R. , Stammers David K.
Published: March 2007

Salmonella typhimurium YegS is a protein conserved in many prokaryotes. Although the function of YegS is not definitively known, it has been annotated as a potential diacylglycerol or sphingosine kinase based on sequence similarity with eukaryotic enzymes of known function. To further characterize YegS, we report its purification, biochemical analysis, crystallization, and structure determination. The crystal structure of YegS reveals a two‐domain fold related to bacterial polyphosphate/ATP NAD kinases, comprising a central cleft between an N‐terminal α/β domain and a C‐terminal two‐layer β‐sandwich domain; conserved structural features are consistent with nucleotide binding within the cleft. The N‐terminal and C‐ terminal domains of YegS are however counter‐rotated, relative to the polyphosphate/ATP NAD kinase archetype, such that the potential nucleotide binding site is blocked. There are also two Ca2+ binding sites and two hydrophobic clefts, one in each domain of YegS. Analysis of mutagenesis data from eukaryotic homologues of YegS suggest that the N‐terminal cleft may bind activating lipids while the C‐terminal cleft may bind the lipid substrate. Microcalorimetry experiments showed interaction between recombinant YegS and Mg2+, Ca2+, and Mn2+ ions, with a weaker interaction also observed with polyphosphates and ATP. However, biochemical assays showed that recombinant YegS is endogenously neither an active diacylglycerol nor sphingosine kinase. Thus although the bioinformatics analysis and structure of YegS indicate that many of the ligand recognition determinants for lipid kinase activity are present, the absence of such activity may be due to specificity for a different lipid substrate or the requirement for activation by an, as yet, undetermined mechanism. In this regard the specific interaction of YegS with the periplasmic chaperone OmpH, which we demonstrate from pulldown experiments, may be of significance. Such an interaction suggests that YegS can be translocated to the periplasm and directed to the outer‐membrane, an environment that may be required for enzyme activity. Proteins 2007. © 2007 Wiley‐Liss, Inc.
Accidental emissions of sulfur oxides from the stack of a sulfuric acid plant: Case study
Authors: Gangopadhyay R. K. , Das S. K.
Published: March 2007

In a manufacturing unit producing sulfuric acid, a large emission of sulfur oxide gases from a stack continued for several minutes. The cause for the emissions could not be determined immediately by the operating people in the control room. The emitted gases not only affected the nearby inhabitants but also affected the vegetation and the environment. This study deals with a release of sulfur oxide gases from a sulfuric acid plant. More than a 100 children in a school, approximately 500 m from the plant boundary, were affected. The incident description and the lessons learned from this tragedy is described in this article. The problem and causes associated with the emission of acid gases and the recommended corrective actions are discussed. © 2007 American Institute of Chemical Engineers Process Saf Prog, 2007
GORD: current drug treatment and maintenance options
Authors: Green Caroline , Mee Anthony
Published: March 2007

Gastro‐oesophageal reflux disease is a com mon complaint and lifestyle changes and drug treatment are usually successful in con trolling symptoms. Our Drug review describes the mode of action and efficacy of the drugs used in treatment and maintenance, followed by an analysis of prescription data, sources of further information and the Datafile. Copyright © 2007 Wiley Interface Ltd
Current management of atrial fibrillation in older people
Authors: Shantsila Eduard , Watson Timothy , Lip Gregory
Published: March 2007

Our series Prescribing in Older People gives practical advice for successful man agement of the special prob lems experienced by this patient group. Here, the authors describe current approaches to the diagnosis and management of atrial fibrillation. Copyright © 2007 Wiley Interface Ltd
The importance of medicines information for patients
Authors: Raynor DK Theo
Published: March 2007

Professor Raynor discusses the importance of spoken and written information for patients about their treat ment and suggests how cur rent patient information leaflets can be improved. Copyright © 2007 Wiley Interface Ltd
No clear winner in MEDAL race
Authors: Plant Michael
Published: March 2007

Prescribing an anti‐inflammatory medication is becoming an increasingly complicated therapeutic decision. This editorial will explore whether the recently published results of the Multinational Etoricoxib and Diclofenac Arthritis Long‐term (MEDAL) studies help to inform that decision.1 First of all, it is worth reviewing the convoluted background that has been reported as much in the newspapers and financial press as in the medical journals.

It was in the 1990s that unacceptable rates of GI toxicity were linked with NSAIDs. MacDonald et al estimated that someone aged over 50 years taking an NSAID had a 0.7 per cent risk of a bleeding or perforated ulcer per year,2 and one out of three of these ulcers would be directly attributable to the drug. Assuming a mortality of 10 per cent it was estimated that NSAID therapy might account for 1200 deaths per year in the UK.

Impressive scientific discoveries showed that benefits and toxicity could possibly be separated. Inhibition of cyclo‐oxygenase‐1 (COX‐1) was found to be the mechanism of GI toxicity, whereas a separate enzyme (COX‐2) mediated the suppression of inflammation. This paved the way for the pharmaceutical companies to develop drugs to selectively inhibit COX‐2. These coxib drugs still caused dyspepsia, but they did not seem to carry the serious GI risks of standard NSAIDs. Admittedly, arguments did rage over the reporting of results for celecoxib (Celebrex) and the lessening of the safety advantage by concomitant low‐dose aspirin.

At this exciting stage COX‐2 inhibitors were also being considered for treatment of other diseases. The hope that cognitive decline in Alzheimer's disease might be slowed proved unfounded, however.3 Although rofecoxib and celecoxib did reduce the rate of recurrence of colorectal polyps,4 the three‐year studies against placebo provided a unique dataset to identify other long‐term side‐effects, including a fourfold increase in cardiovascular thrombotic events with rofecoxib.5 Amid a flurry of publicity rofecoxib was withdrawn, and safety warnings were sent to all doctors in the UK about COX‐2 inhibitors as a class. Litigation cases were brought, confidence fell and so did share prices. Copyright © 2007 Wiley Interface Ltd
Rimonabant (Acomplia): a novel adjunctive treatment for obesity
Authors: Barnett Anthony
Published: March 2007

Rimonabant is the first selective cannabinoid‐1 receptor inhibitor for use in the treatment of obesity. In this article Professor Barnett describes its novel mode of action and the results of clinical trials of its efficacy and safety. Copyright © 2007 Wiley Interface Ltd
Atomic layer epitaxy of GaMnAs on GaAs(001)
Authors: Ozeki M. , Haraguchi T. , Fujita A.
Published: March 2007

A self‐limiting mechanism in atomic layer epitaxy (ALE) has been investigated for the heterogrowth of GaMnAs on GaAs(001) substrate. In the ALE, trimethylgallium, bismethylcyclopentadienylmanganese and trisdimethylaminoarsine were used as source materials of gallium, manganese and arsenic atoms, respectively. Although the growth of GaMnAs was carried out at a high growth temperature of 500 °C, a distinct self‐limiting mechanism was observed for the manganese alloy composition up to 6% and the epitaxial layer had no indications of including MnAs phase. The layer showed an atomically flat surface morphology reflecting the self‐limiting growth. The self‐limiting mechanism was largely affected by the lattice mismatch between GaMnAs epitaxial layer and GaAs substrate. When the manganese alloy composition exceeded 7%, the self‐limiting mechanism was broken and MnAs precipitates were observed in the epitaxial layer. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Transistor with organic emitter and electrodeposited Au base
Authors: Delatorre R. G. , Munford M. L. , Zhou Q. , Pasa A. A. , Schwarzacher W.
Published: March 2007

In this work we present results from a metal‐base transistor consisting of organic C60 as emitter, an ultra‐thin Au as base and n‐Si as collector. The Au layer was directly electrodeposited on the n‐Si surface from a commercial electrolyte containing K2SO3 and Au sulphite complexes. The fullerene emitter was subsequently evaporated on top of the Au layer. For a base thickness of 10 nm the common‐base current gain is close to 1, which is a strong evidence that the transistor is a permeable base device. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Surface modification of EPDM in r.f. plasma: process optimization and surface characterization
Authors: Moraes J. H. , Maciel H. S. , Dutra J. C. N. , Mello S. A. C. , da Silva Sobrinho A. S. , Massi M.
Published: March 2007

Due to the excellent thermal and mechanical properties, the EPDM rubber is used as protective film in the aerospace industry. However, its chemical composition and structure do not allow good adhesive properties, making necessary a surface treatment to improve adhesion properties. Most of the conventional chemical methods make use pollutant solvents. Cold plasma is a clean technology that becomes an important alternative for treating these material surfaces. In this work we present a study of the EPDM rubber surface treatment by plasma. The process was conducted in a RIE plasma system excited by r.f. power using N2 and Ar gas mixtures. A significant improvement of the surface properties regarding to the adhesion properties was obtained. An optimization of the plasma parameters, such as gas ratio mixture, rf power, total gas pressure and treatment time is presented. The rubber surface properties were analyzed by goniometry and AFM. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Raman shift on n‐doped amorphous carbon thin films grown by electron beam evaporation
Authors: Rebollo P. B. , Freire L. F. , Lozada M. R. , Palomino M. R. , Jiménez S. S. , Zelaya A. O.
Published: March 2007

The structural properties of carbon thin films synthesized under an atmosphere of nitrogen by means of electron beam evaporation were studied by Raman scattering spectroscopy. The electron beam evaporation technique is an important alternative to grown layers of this material with interesting structural properties. The observed shift of the Raman G band shows that the structure of the films tends to become more graphitic upon the increase of the deposition time. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Study of Te diffused into GaSb by photoluminescence and HRXRD
Authors: Vargas‐Sanabria R. , Rosendo E. , Martínez J. , Díaz T. , Juárez H. , García G. , Rosendo‐Francisco P. , Rubín M. , de Anda F.
Published: March 2007

Photoluminescence (PL) and High Resolution X‐Ray Diffraction (HRXRD) measurements were used to study the diffusion of Te on GaSb‐p thin films deposited on GaSb‐n substrates by Liquid Phase Epitaxy (LPE). The studied samples consist of an n‐type layer on a p‐type layer to carry out the diffusion. The diffusion process was done through thermic treatment at 450 °C and 2, 4 and 6 hours in to the hydrogen atmosphere. After carrying out the heat treatment, the n‐type layer was removed with the purpose of studying the diffusion behavior of Te. The PL spectra show that when the time of diffusion increases, the signal produced by the exitonic transitions increases its intesity, this can be attributed to the increase of the concentration of Te in the GaSb‐p film. The X‐ray spectra show that in agreement it increases the time of diffusion, the amount of Te increases until having a single peak to 6 hrs of diffusion. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Structural evolution of nanocrystalline silicon studied by high resolution transmission electron microscopy
Authors: Ponce A. , Benami A. , Santana G. , Alonso J. C. , Aguilar‐Hernández J. , Contreras‐Puente G. , Ortiz A. , Fandiño J. , Romeu D.
Published: March 2007

In this work, nanocrystalline silicon (nc‐Si) embedded in amorphous silicon nitride (a‐SixNy) films have been characterized by High Resolution Transmission Electron Microscopy (HRTEM). The films have been grown by remote plasma enhanced chemical vapour deposition (RPECVD) onto silicon substrates using a mixture of SiCl4, NH3 and H2. Subsequently, the sample has been introduced to an annealed process. The nanocrystalline inclusions have been measured from the analysis of HRTEM images. The size of nc‐Si inclusions is modified due to the annealing process. The diameter of nc‐Si inclusions in as‐grown films vary from 1.3 to 3.1 nm. In annealed films, a high density of new clusters with reduction of 1 nm of those diameters is observed, as well as the coalescence phenomenon among some nc‐Si inclusions is observed too. Consequently, the diameters of annealed films nc‐Si inclusions range from 0.7 to 4 nm. The thin films show an excellent photoluminescence emission. The density per unit area and size of the nc‐Si inclusions are correlated with the PL emissions. The influence of the structural changes of the nc‐Si on the PL emissions is discussed. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Thermodynamics of InxGa1–xN MOVPE using x ‐dependent interaction parameter
Authors: Moon Won Ha , Kim Changsung Sean , Choi Chang Hwan
Published: March 2007

Thermodynamic properties of Inx Ga1–x N MOVPE are investigated using x ‐dependent interaction parameter. The interaction parameter (Ω = –1.3435x + 6.1607 (kcal/mol)) dependent on In composition is calculated using a molecular‐mechanics method to investigate the phase stability of InGaN. This parameter is more reliable than that proposed until now. The phase diagram and critical temperature (1392 K at x = 0.44) of Inx Ga1–x N are also obtained. With this interaction parameter, many thermodynamic characteristics of InGaN by the change of In composition, input V/III ratio, and input mol ratio of group III sources are calculated to predict the growth condition of InGaN. These results are in agreement with other data for InGaN. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Photoluminescence and TEM characterization of (AlyGa1–y)1–xInxP layers grown on graded buffers
Authors: Novak J. , Hasenöhrl S. , Kučera M. , Vavra I. , Štrichovanec P. , Kovác J. , Vincze A.
Published: March 2007

Composition, crystallographic quality and low temperature photoluminescence of AlGaInP quaternary layers were studied. These layers were grown on the InGaP/GaP graded buffers by metalorganic vapour phase epitaxy. Final composition of the graded buffer top layer was xIn = 0.24. Incorporation of the small amount Al into quaternary led to a substantial improvement of the surface morpohology and crystallographic quality observed in cross‐sectional TEM view. Incorporation of higher amount of Al (above 1%) led to the increase of lattice mismatch, decrease of In content in the alloy and to the indirect band gap. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Synthesis of PbI2 with admixture of rare earth elements: Electrical and optical properties
Authors: Matuchova M. , Zdansky K. , Zavadil J.
Published: March 2007

Lead iodide is a promising material applicable for X‐ray and gamma ray detectors operating at room temperature. It has been prepared by direct synthesis of elements lead and iodine and purified by zone melting. The Bridgman‐Stockbarger method has been used for growth of single crystals. The influence of rare earth elements (cerium, gadolinium, terbium, holmium, erbium, thulium and ytterbium) on the quality of resulting material has been investigated. The electrical properties have been studied by the measurement of resistivity. Optical properties have been evaluated by using low temperature photoluminescence spectroscopy. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Bidirectional current 4H‐SiC VJFET
Authors: Brosselard P. , Tournier D. , Mihaila A. , Udrea F. , Rashid S. J. , Godignon P. , Amaratunga G. , Millán J.
Published: March 2007

Silicon Carbide is an attractive material to develop new generation of power devices due to its outstanding physical and thermal properties. Due to the JFET performances, the reverse mode shows a great interest for power applications particularly concerning bidirectional current capability. Besides, the device temperature behaviour has been characterised up to 300 °C. We have observed excellent temperature performances in the reverse and forward conduction modes since Ron only shows a ×5 and ×4 increase, respectively, from 30 °C to 300 °C. In blocking mode, the leakage current is below the nA range at room temperature and rises the μA range at 300 °C, remaining very low compared to Si devices. In conclusion, one may state that the SiC JFET is a suitable switch for high temperature power applications, showing bidirectional current capability. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)