bluuebunny/crossref_metadata_2025_split huggingface dataset:
Theoretical studies on the carcinogenicity of polycyclic aromatic hydrocarbons
Authors: Vijayalakshmi K. Periya , Suresh Cherumuttathu H. 
Published: March 2008

AbstractThe distinct molecular regions of a set of 28 polycyclic aromatic hydrocarbons (PAHs) showing varying degrees of carcinogenic activity (CA) have been analyzed on the basis of their calculated molecular electrostatic potential (MESP) at B3LYP/6‐31+G(d,p) level of theory. The MESP, being a property directly related to electron density, clearly distinguishes the electron dense centers in the molecule into K, L, M, and newly defined N regions. Further, a quantitative structure activity relationship (QSAR) model of carcinogenicity is developed using the volume of MESP lobes at the named regions for a set of 17 carcinogenic molecules with experimentally known CA index. The QSAR equation suggested that all the geometrical regions are significant in determining the carcinogenic property of PAHs. The model clearly showed that K and M regions have activating carcinogenic effect whereas L and N regions have deactivating carcinogenic effect. The CA showed considerable enhancement when any three distinct regions are present in a PAH. On the other hand, all the PAH systems with only one type of region are inactive irrespective of whether the region is activating or deactivating. Similarly, molecules showing the presence of two types of regions are either inactive or weakly active. The essential features of both the “K, L region” and the “bay region” theories of carcinogenesis are well evident in the new QSAR model, as the former theory works on the basis of activating K and deactivating L regions whereas the latter theory is related with the activating M region. © 2008 Wiley Periodicals, Inc. J Comput Chem, 2008
Efficient free energy calculation of water across lipid membranes
Authors: Shinoda Keiko , Shinoda Wataru , Mikami Masuhiro 
Published: March 2008

AbstractAn efficient free energy (FE) calculation of a water molecule to go across lipid membranes is presented. Both overlapping distribution and cavity insertion Widom methods are complementarily used. The former is useful for a dense region where water molecules are found, i.e., from the interfacial to bulk water region, while the latter works well in the low density region, i.e., the hydrocarbon region. Since both methods evaluate the excess chemical potential of water, the obtained FE profile is free from the fitting problem usually arisen when a FE difference method is used. A diphytanyl phosphatidylcholine bilayer is used for our test calculations. An excellent and fast convergence of the chemical potential is obtained when each method is applied for the appropriate region. The estimated FE barrier using the Ewald method for the electrostatic interaction is ∼7.2 kcal/mol, which is higher than that using the interaction cutoff of 20 Å by about 0.9 kcal/mol. © 2008 Wiley Periodicals, Inc. J Comput Chem 2008
Hypoxia promotes chondrogenesis in rat mesenchymal stem cells: A role for AKT and hypoxia‐inducible factor (HIF)‐1α
Authors: Kanichai Manoj , Ferguson Damien , Prendergast Patrick J. , Campbell Veronica A. 
Published: March 2008

AbstractMesenchymal stem cells (MSCs) are multipotent cells capable of developing along the chondrogenic, osteogenic and adipogenic lineages. As such, they have received interest as a potential cell source for tissue engineering strategies. Cartilage is an avascular tissue and thus resides in a microenvironment with reduced oxygen tension. The aim of this study was to examine the effect of a low oxygen environment on MSC differentiation along the chondrogenic route. In MSCs exposed to chondrogenic growth factors, transforming growth factor‐β and dexamethasone, in a hypoxic environment (2% oxygen), the induction of collagen II expression and proteoglygan deposition was significantly greater than that observed when cells were exposed to the chondrogenic growth factors under normoxic (20% oxygen) conditions. The transcription factor, hypoxia‐inducible factor‐1α (HIF‐1α), is a crucial mediator of the cellular response to hypoxia. Following exposure of MSCs to hypoxia (2% oxygen), HIF‐1α translocated from the cytosol to the nucleus and bound to its target DNA consensus sequence. Similarly, hypoxia evoked an increase in phosphorylation of both AKT and p38 mitogen activated protein kinase, upstream of HIF‐1α activation. Furthermore, the PI3 kinase/AKT inhibitor, LY294002, and p38 inhibitor, SB 203580, prevented the hypoxia‐mediated stabilisation of HIF‐1α. To assess the role of HIF‐1α in the hypoxia‐induced increase in chondrogenesis, we employed an siRNA knockdown approach. In cells exposed to HIF‐1α siRNA, the hypoxia‐induced enhancement of chondrogenesis, as evidenced by upregulation of collagen II, sox‐9 and proteoglycan deposition, was absent. This provides evidence for HIF‐1α being a key mediator of the beneficial effect of a low oxygen environment on chondrogenesis. J. Cell. Physiol. 216: 708–715, 2008, © 2008 Wiley‐Liss, Inc.
Sonographic appearance of angiolymphoid hyperplasia with eosinophilia in the upper arm
Authors: Mak Chee‐Wai , Tzeng Wen‐Sheng , Chen Chin‐Yu , Chou Chung‐Kuao , Lin Ching‐Nan 
Published: March 2008

AbstractAngiolymphoid hyperplasia with eosinophilia is an uncommon benign condition characterized by cutaneous nodules involving primarily the head and neck regions of young adults. We report thecase of a 49‐year‐old woman with such a lesion in the arm. Sonographically, the lesion exhibited a hypoechoic rim and an echogenic central portion. On color Doppler imaging, the central portion was markedly vascular. © 2008 Wiley Periodicals, Inc. J Clin Ultrasound, 2008.
Zinc bioavailability in wheat grain in relation to phosphorus fertiliser, crop sequence and mycorrhizal fungi
Authors: Ryan Megan H , McInerney Jennifer K , Record Ian R , Angus John F 
Published: March 2008

AbstractBACKGROUND: While human diets are often deficient in zinc (Zn), the impacts of crop management on Zn in cereal grains are rarely examined. In this study the effect of phosphorus (P) fertiliser and crop sequence (wheat following canola, linola, fallow or pasture) on wheat grain Zn concentration and bioavailability for humans was investigated.RESULTS: The Zn concentration of wheat grain decreased by 33–39% in response to P fertiliser. It was also 30–40% lower for crops following canola and fallow than for those following linola and pasture. P fertiliser decreased the colonisation of arbuscular mycorrhizal fungi (AMF) in wheat roots, and canola and fallow led to lower colonisation than linola and pasture. Since AMF are known to assist in soil uptake of immobile nutrients such as Zn, it is hypothesised that P fertiliser and crop sequence affected grain Zn concentration through AMF. P fertiliser also increased the concentrations of grain P by 17% and grain phytic acid (PA) by 19%, but had little effect on the concentrations of calcium (Ca), iron (Fe) and polyphenols. Other impacts of crop sequence were slightly higher concentrations in grain of P after pasture and Fe after canola. The bioavailability of grain Zn, as shown by the PA:Zn and Ca × PA:Zn molar ratios, mostly reflected Zn concentration and was low in all treatments. After milling, the PA:Zn molar ratio suggested low Zn bioavailability for flour from wheat grown with P fertiliser after canola or fallow.CONCLUSION: Crop management can affect the bioavailability of Zn in wheat grain, with practices leading to high yields potentially leading to low Zn bioavailability. Copyright © 2008 Society of Chemical Industry
Supercritical fluid chromatography‐mass spectrometry for chemical analysis
Authors: Li Fangbiao , Hsieh Yunsheng 
Published: March 2008

AbstractChromatography with a supercritical fluid as the mobile phase was suggested more than four decades ago (Klesper, E., Corwin, A. H., Turner, D. A., J. Org. Chem. 1962, 27, 700–701). Supercritical fluid chromatography (SFC) is basically a hybrid of GC and LC that eases the resolution of a mixture of compounds not conveniently resolved by either GC or LC. The mobile phases for SFC have low viscosities and high diffusion coefficients compared to those for HPLC and allow for high efficiency separations. SFC uses supercritical fluid as the mobile phase, polar organic solvents as the modifiers in conjunction with acidic/basic compounds as additives to run the chromatographic process like in HPLC. In many applications, SFC‐based methods are advantageous over HPLC‐based methods as a separation tool in terms of efficiency and economical impact perspectives. Today, the availability of commercial hardware and API interfaces with a mass spectrometer makes SFC even more widely applicable for chemical analysis in many research fields. This review summarizes a variety of novel SFC‐MS methods for chemical analysis that have been reported in the peer‐reviewed publications.
Photoacoustic imaging of port‐wine stains
Authors: Kolkman Roy G.M. , Mulder Miranda J. , Glade Conrad P. , Steenbergen Wiendelt , van Leeuwen Ton G. 
Published: March 2008

AbstractBackground and ObjectiveTo optimize laser therapy of port‐wine stains (PWSs), information about the vasculature as well as lesion depth is valuable. In this study we investigated the use of photoacoustic imaging (PAI) to obtain this information.Study Design/Materials and MethodsPAI uses pulsed light to generate ultrasound upon absorption of short light pulses by blood. In this study we used PAI to image vasculature in PWSs in three human volunteers. Two‐dimensional imaging (scan direction vs. depth) was carried out by scanning a double‐ring photoacoustic sensor over the tissue surface.ResultsIn the photoacoustic images we observed an increased photoacoustic signal intensity at the locations of the PWS that is associated with increased vascularization. From the obtained images we measured the thickness of the vascular layer and estimated lesion depth. In some cases single vessels could be observed at the position of the PWS whereas in other cases the PWS appeared as a region with large photoacoustic signal intensity.ConclusionsPAI has the potential to reveal information about the lesion depth as well as thickness of the vascular layer. Laser Surg. Med. 40:178–182, 2008. © 2008 Wiley‐Liss, Inc.
Perturbation bounds for weighted polar decomposition in the weighted unitarily invariant norm
Authors: Yang Hu , Li Hanyu 
Published: March 2008

AbstractIn this paper, by generalizing the ideas of the (generalized) polar decomposition to the weighted polar decomposition and the unitarily invariant norm to the weighted unitarily invariant norm, we present some perturbation bounds for the generalized positive polar factor, generalized nonnegative polar factor, and weighted unitary polar factor of the weighted polar decomposition in the weighted unitarily invariant norm. These bounds extend the corresponding recent results for the (generalized) polar decomposition. In addition, we also give the comparison between the two perturbation bounds for the generalized positive polar factor obtained from two different methods. Copyright © 2008 John Wiley & Sons, Ltd.
Uganda's decentralised primary education: musical chairs and inverted elite capture in School Management Committees
Authors: Prinsen Gerard , Titeca Kristof 
Published: March 2008

AbstractDecentralisation policies in Africa increasingly place responsibilities and resources for the provision of public services in the hands of public bodies at the lowest level, for example in School Management Committees (SMCs). This paper questions whether elite capture, which is considered a major reason for the ineffectiveness of the management of public services at a national level, also characterises SMCs. On the basis of field research in Uganda, it is argued that elite capture does not trickle down to the lowest levels in the management of public services. Copyright © 2008 John Wiley & Sons, Ltd.
A method for optimal control in boundary‐layer flow
Authors: Dumitrache Alexandru 
Published: March 2008

AbstractA methodology for active flow control which couples unsteady flow fields and controls is described. Active‐control methods are used to maintain laminar flow in a region in which the natural instabilities lead to turbulent flow. The simplest form of control which might achieve this objective is the wave‐cancellation approach. The case of boundary layer instability suppression is considered as the initial validation and test case. Control is effected through the injection or suction of fluid through a single orifice on the boundary. The optimal control theory provides an approach which does not require a priori knowledge of the flow. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Local stochastic analysis of the effective material response of disordered two‐dimensional model foams
Authors: Hardenacke Volker , Hohe Jörg 
Published: March 2008

AbstractThe objective of the present study is a numerical analysis of disorder effects in solid structural foams caused by their random irregular micro structure. Using a strain energy based concept, the effective material response is computed in a probabilistic homogenization based on the analysis of a large scale statistically representative volume element. The stochastic information about the scatter in the material response on the lowest possible level is generated by a subsequent division of the representative volume element in substructures consisting of a single cell wall intersection and parts of the adjacent cell walls. For each of the substructures a homogenization analysis is performed. The results for the local effective stress and strain components are evaluated by means of stochastic methods. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Investigation of properties of the solutions of hyperbolic stochastic PDEs
Authors: Ignatyev Oleksiy 
Published: March 2008

AbstractIn this paper we investigate the compact support property of the solutions of hyperbolic Stochastic PDE (SPDE) providing that initial condition function is deterministic and has compact support property. First, to approach this problem, we consider semi‐SPDE. It turns out that in the semi‐SPDE case solution u (t, x) preserve compact support property. When we consider SPDE, we use the stochastic differential‐difference equations (SDDE) approach. It turns out that in SPDE case solution u (t, x) does not preserve compact support property. So, if we compare the semi‐SPDE and SPDE then it becomes obvious that differentiation in space in SPDE plays crucial role and influence the behavior of the solution. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Graphical simulation of a new concept of low sized surgical parallel robot for camera guidance in minimally invasive surgery
Authors: Vaida C. , Pisla D. , Plitea N. 
Published: March 2008

AbstractRobotic systems have been developed in every field where a further progress was constricted due to the human limitations in terms of speed, precision, fatigue, repeatability, strength, safety etc. One of the pioneer fields for robots is their assimilation in surgery, especially in minimally invasive procedures which aim the treatment of a disease with minimum damage to healthy tissue and suffering for the patient [1], [2]. The paper presents a complex simulation system used for the study of the characteristics of a new low sized parallel robot used for minimally invasive surgery (MIS). (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A contractive operator solution of an airfoil design inverse problem
Authors: Šimák Jan , Pelant Jaroslav 
Published: March 2008

AbstractThis paper deals with a numerical method for an airfoil design which was presented in [3, 5]. This method is intended for design of an airfoil from a given velocity distribution along a mean camber line. The method is based on searching for a fixed point of a contractive operator. This operator combines an inexact inverse operator and equations describing the flow. A subsonic flow is assumed, the flow is described by a system of the Euler equations which is solved by an implicit finite volume method. The Newton method is applied to the solution of the nonlinear system. The resulting system of linear algebraic equations is solved by GMRES method, the Jacobian‐free version is described. The inexact inverse operator consists of a middle curve function and a thickness function, both depending on the given velocity distribution. In addition to the velocity distribution the velocity in infinity is given. The angle of attack is determined so that the stagnation point is in a specific position. Successful numerical results are presented. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A method for determining control inputs for prescribed accelerations of the end‐effector of a motion‐simulator robot
Authors: Tändl Martin , Kecskeméthy Andrés 
Published: March 2008

AbstractDescribed in this paper is an approach for generating control inputs for an industrial Kuka robot such that it produces prescribed linear acceleration time histories for a given point of the end‐effector. The method takes into account the workspace limits, and uses the internal interpolation cycle of the robot controller to generate the corresponding trajectories that will produce the prescribed accelerations. The PI parameters of the internal interpolation are identified from test measurements. The control scheme consists in producing time‐varying values for the desired angle values of the interpolation algorithm, making the changes as the algorithm proceeds and thus generating smooth trajectories. The resulting acceleration of these trajectories is compared to the prescribed accelerations, and an optimization procedure is run such as to determine the required time‐histories of the desired angles for the interpolation algorithm such that both accelerations match. The approach is demonstrated for the example of a 500kg payload Kuka robot that is aimed at producing given motions as a physical motion simulator (e. g. for cars or complex working machines). It is shown that the desired accelerations can be generated accurately and with high repeatability, making the approach suitable for example for simulating car rollover tests. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Linear and nonlinear problems of active sound control
Authors: Utyuzhnikov Sergei V. , Ryaben'kii Victor S. , Turan Ali 
Published: March 2008

AbstractThe problem of active shielding of some domain from the effect of the field generated in another domain is considered. The active shielding is implemented via the placement of additional sources in such a way that the total contribution of all sources leads to the desirable effect. The obtained solution does not require either the knowledge of the particular Green's function or any other information on source distribution and the surrounding medium. It is also important that along with undesirable field to be shielded, a desirable field can be admitted in the analysis. The solution of the problem requires only knowledge of the total field on the perimeter of the shielded domain. The active shielding sources are obtained for both the linear and nonlinear formulations of the problem. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The effect of EVA content on the processing parameters and the mechanical properties of LDPE/ground tire rubber blends
Authors: Mészáros L. , Tábi T. , Kovács J.G. , Bárány T. 
Published: March 2008

AbstractIn this work, thermoplastic elastomers were prepared based on low‐density polyethylene (LDPE) and ground tire rubber (GTR). To improve the adhesion and achieve better rubber‐like properties, ethylene vinyl acetate copolymer (EVA) was selected and used as a compatibilizer. The GTR and EVA content were varied between 0–45 and 0–20 wt%, respectively. Blends with different composition were produced from the raw materials on a twin screw extruder. Tensile and instrumented falling weight impact (IFWI) specimens were injection molded from the granulated blends. Injection pressure and the shrinkage of the IFWI specimens were measured. Besides the tensile and IFWI tests, the cut cross‐sections were inspected with a scanning electron microscope. Based on the results, it can be stated that the application of EVA as a compatibilizer is essential for even lower weight percentage to ensure the rubber‐like properties, but as the EVA content is increased, only less additional improvement can be detected. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers
An in‐process ultrasonic approach to investigating the relaxation of orientation and disorientation of polymer melts
Authors: Li Jiang , Sun Zhigang , Tatibouët Jacques , Jen Cheng‐Kuei 
Published: March 2008

AbstractThe orientation and relaxation behaviors of a low‐density polyethylene melt and polypropylene melts with different melt indices undergoing a shear flow in a restricted channel were investigated by using ultrasound. A capillary rheometer was used to force the polymer melt through a slit die equipped with pressure, temperature, and ultrasound sensors, and the variation of ultrasound velocity traversing the melt was measured. Experimental results revealed that due to different mechanisms involved, the relaxations of orientation and disorientation processes show different dependences of ultrasound velocity on shear rate, temperature, and melt index. POLYM. ENG. SCI., 2008. Published 2008 Society of Plastics Engineers
Applications of interferometric ellipsometry
Authors: Kawabata S. , Matsumoto T. , Wakaki M. , Chen J. 
Published: March 2008

AbstractIn the polarization division interferometric ellipsometry, two orthogonal linearly polarized light are superposed with an interferometer and the state of polarization of the composite light is measured to obtain the phase difference between the two orthogonal linearly polarized light. The Polarimetric Interferometer based on the polarization division interferometric ellipsometry was devised to carry out the measurement of the thickness of transparent thin films. It was capable of measuring the optical thickness of the films of an order of nm with ease. It was applied to observe the surface dynamics caused by water vapor adsorption and desorption on a glass substrate. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optical properties of PZT thin films by spectroscopic ellipsometry and optical reflectivity
Authors: Chvostová D. , Pajasová L. , Železný V. 
Published: March 2008

AbstractOptical properties of PbZr0.3Ti0.7O3 (PZT) thin films have been investigated using variable angle spectroscopic ellipsometry (VASE) and near‐normal spectroscopic reflectivity (NNSR). The measurements were carried out in the spectral range 1 – 6 eV up to 500 °C by VASE and in the range 1 – 12 eV by NNSR at room temperature. The PZT films of two different thicknesses (730 and 900 nm) were deposited on platinized Si substrates by sol‐gel (CSD) technique. VASE and NNSR data were simultaneously evaluated to obtain the optical response functions (e.g. complex refractive index, dielectric function) and thicknesses of these films. Several dispersion models were used to fit the experimental data and determine the optical response functions and geometric parameters of the thin films. The absorption edge of PZT films was found about 3.2 eV and its temperature dependence was also determined. These results werere compared with the Kramers‐Kronig analysis. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)