bluuebunny/crossref_metadata_2025_split huggingface dataset:
Oxidative DNA damage in osteoarthritic porcine articular cartilage
Authors: Chen Antonia F. , Davies Catrin M. , De Lin Ming , Fermor Beverley 
Published: August 2008

AbstractOsteoarthritis (OA) is associated with increased levels of reactive oxygen species. This study investigated if increased oxidative DNA damage accumulates in OA articular cartilage compared with non‐OA articular cartilage from pigs with spontaneous OA. Additionally, the ability of nitric oxide (NO) or peroxynitrite (ONOO−) induced DNA damage in non‐OA chondrocytes to undergo endogenous repair was investigated. Porcine femoral condyles were graded for the stage of OA, macroscopically by the Collins Scale, and histologically by the modified Mankin Grade. Levels of DNA damage were determined in non‐OA and OA cartilage, using the comet assay. For calibration, DNA damage was measured by exposing non‐OA chondrocytes to 0–12 Gray (Gy) of X‐ray irradiation. Non‐OA articular chondrocytes were treated with 0–500 µM of NO donors (NOC‐18 or SIN‐1), and DNA damage assessed after treatment and 5 days recovery. A significant increase (P < 0.01) in oxidative DNA damage occurred in OA chondrocytes in joints with Mankin Grades 3 or greater, compared to non‐OA chondrocytes. The percentage of nuclei containing DNA damage increased significantly (P < 0.001) from early to late grades of OA. An increase of approximately 0.65–1.7 breaks/1,000 kb of DNA occurred in OA, compared to non‐OA nuclei. NOC‐18 or SIN‐1 caused significant DNA damage (P < 0.001) in non‐OA chondrocytes that did not undergo full endogenous repair after 5 days (P < 0.05). Our data suggest significant levels of oxidative DNA damage occur in OA chondrocytes that accumulates with OA progression. Additionally, DNA damage induced by NO and ONOO− in non‐OA chondrocytes does not undergo full endogenous repair. J. Cell. Physiol. 217: 828–833, 2008. © 2008 Wiley‐Liss, Inc.
Thinking straight: New strategies are needed for ethical leadership
Authors: Marcy Richard T. , Gentry William A. , McKinnon Rob 
Published: August 2008

AbstractAfter all the high‐profile examples of ethical transgressions by top leaders in recent years, why do some leaders continue to make ethical mistakes? New research suggests that there is a pronounced disconnect between what leaders say they would do when faced with an ethical dilemma and what they might actually do. It also suggests that only when leaders begin to use specific strategies aimed directly at addressing certain biases and situational pressures will they be able to avoid ethical problems.
Selling your ideas: Giving some wattage to those lightbulbs
Authors: Scharlatt Harold 
Published: August 2008

AbstractWhen you want your organization to buy into your ideas, there are two important things to consider. The first is scanning your organization's environment to determine such things as how well each idea fits with the organization's goals and what level of support you'll need from key people. The second is collecting a set of tactics you can use to begin communicating and implementing your ideas. Doing these two things will improve your chances of accomplishing your objective—solving a problem or making an improvement for the benefit of everyone.
Selenoprotein deficiency enhances radiation‐induced micronuclei formation
Authors: Baliga Manjeshwar S. , Diwadkar‐Navsariwala Veda , Koh Timothy , Fayad Raja , Fantuzzi Giamila , Diamond Alan M. 
Published: August 2008

AbstractThe availability of selenium and the levels of specific selenoproteins might affect cancer risk by influencing the ability of DNA damaging agents to cause genomic instability and mutations. Transgenic mice that express reduced levels of selenoproteins and previously shown to be more susceptible to pathology associated with cancer development were used to study this possibility. These mice were exposed to X‐rays and DNA damage assessed in the erythrocytes, where micronuclei formation was higher compared to the same cells obtained from irradiated wild‐type controls. To determine whether the selenoprotein glutathione peroxidase‐1 (GPx‐1) might be involved in this protection, its levels were reduced by siRNA targeting in LNCaP human prostate cells. UV‐induced micronuclei frequency was higher in these cells compared to control‐transfected cells. These results indicate a role for selenoproteins in protecting DNA from damage and support human data implicating GPx‐1 as a possible target of the chemoprotective effect of selenium.
A comparison of FE–BE coupling schemes for large‐scale problems with fluid–structure interaction
Authors: Brunner Dominik , Junge Michael , Gaul Lothar 
Published: August 2008

AbstractTo predict the sound radiation of structures, both a structural problem and an acoustic problem have to be solved. In case of thin structures and dense fluids, a strong coupling scheme between the two problems is essential, since the feedback of the acoustic pressure onto the structure is not negligible. In this paper, the structural part is modeled with the finite element (FE) method. An interface to a commercial FE package is set up to import the structural matrices. The exterior acoustic problem is efficiently modeled with the Galerkin boundary element (BE) method. To overcome the well‐known drawback of fully populated system matrices, the fast multipole method is applied. Different coupling formulations are investigated. They are either based on the Burton–Miller approach or use a mortar coupling scheme. For all cases, iterative solvers with different preconditioners are used. The efficiency with respect to their memory consumption and computation time is compared for a simple model problem. At the end of the paper, a more complex structure is simulated. Copyright © 2008 John Wiley & Sons, Ltd.
An efficient out‐of‐core multifrontal solver for large‐scale unsymmetric element problems
Authors: Reid J. K. , Scott J. A. 
Published: August 2008

AbstractIn many applications where the efficient solution of large sparse linear systems of equations is required, a direct method is frequently the method of choice. Unfortunately, direct methods have a potentially severe limitation: as the problem size grows, the memory needed generally increases rapidly. However, the in‐core memory requirements can be limited by storing the matrix and its factors externally, allowing the solver to be used for very large problems. We have designed a new out‐of‐core package for the large sparse unsymmetric systems that arise from finite‐element problems. The code, which is called HSL_MA78, implements a multifrontal algorithm and achieves efficiency through the use of specially designed code for handling the input/output operations and efficient dense linear algebra kernels. These kernels, which are available as a separate package called HSL_MA74, use high‐level BLAS to perform the partial factorization of the frontal matrices and offer both threshold partial and rook pivoting. In this paper, we describe the design of HSL_MA78 and explain its user interface and the options it offers. We also describe the algorithms used by HSL_MA74 and illustrate the performance of our new codes using problems from a range of practical applications. Copyright © 2008 John Wiley & Sons, Ltd.
Migration and surface modification in polypropylene (PP)/polyhedral oligomeric silsequioxane (POSS) nanocomposites
Authors: Tang Yong , Lewin Menachem 
Published: August 2008

AbstractThis paper reports on the migration of POSS‐based nanocomposites both by annealing the melt and by heating the solid blend in the microwave oven. The migration proceeds to all surfaces of the sample as verified by ATR‐FTIR spectra of the bottom and top surfaces. Concentrations of POSS on the surface, exceeding 50%, are obtained. Polarity of the matrix increases POSS migration. During annealing at 190°C, a sublimation of POSS from the upper surface occurs. In air, sublimation is decreased by oxidizing the organic side groups of POSS and the PP to non‐volatile moieties. No sublimation occurs below 100°C. The AFM and SEM‐EDAX verified the high POSS concentration on the surface and indicated very pronounced roughness of the surface of the sample. The static contact angle measurements reveal very high hydrophobicity as well as low surface free energy (SFE) of the surface of the sample, which is close to that of Teflon and of pristine POSS. The migration of POSS is due to its lower surface tension, the entropy considerations, its lower cohesive energy with the matrix chains as compared to the cohesion energy between the chains, and the density and temperature fluctuations of the matrix chains which upon relaxation repulse and propel POSS to the surfaces. Copyright © 2008 John Wiley & Sons, Ltd.
Ultrafast photoluminescence of nanocrystalline diamond films
Authors: Preclíková J. , Trojánek F. , Kromka A. , Rezek B. , Dzurňák B. , Malý P. 
Published: August 2008

AbstractWe report on ultrafast photoluminescence of nanocrystalline diamond membranes and films on silicon and fused silica glass measured by femtosecond upconversion technique. The nanodiamond samples were prepared by microwave plasma enhanced CVD technique. Photoluminescence with very fast non‐exponential decay with the effective time of about 1 ps was observed in the investigated spectral interval 1.8–2.8 eV. The decay was spectrally dependent being faster at higher photon energies. We have found that the photoluminescence dynamics are affected by temperature and ambient pressure. We interpret the photoluminescence dynamics in terms of charge‐carrier relaxation via the continuum of the nanocrystal surface‐related energy states lying energetically below the diamond band‐gap energy. The results can be explained by the spectral dependence of the density of these states and its changes due to ambient conditions. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The influence of thermal annealing on the electronic defect states in nanocrystalline CVD diamond films
Authors: Remes Z. , Kromka A. , Potmesil J. , Vanecek M. 
Published: August 2008

AbstractThe photosensitive, nominally undoped nanocrystalline diamond (NCD) films were grown on insulating substrates at a relatively low temperature below 600 °C. The NCD films were exposed to the hydrogen plasma and then briefly to the oxide plasma. This treatment significantly reduced the surface conductivity and enhanced the bulk photosensitivity. The broad optical spectral range (200–2000 nm) photocurrent and optical absorption spectra were measured by the dual‐beam photoconductivity (DBP), Fourier‐transform photocurrent spectroscopy (FTPS) in amplitude modulated step scan mode, optical transmittance and reflectance and photothermal deflection spectroscopy (PDS). The photoionization cross section spectrum of our NCD films is dominated by the non‐diamond phase with the photo‐ionization threshold energy at about 1 eV. At 350 °C the thermal annealing increased the concentration of defects related to the non‐diamond phase and deteriorated the UV photosensitivity. The significant increase of the optical absorption was observed after annealing at 500 °C. The hydrogenation can reduce to some extend the defects created by the thermal annealing. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Detonation nanodiamond and onion‐like carbon: applications in composites
Authors: Shenderova O. , Jones C. , Borjanovic V. , Hens S. , Cunningham G. , Moseenkov S. , Kuznetsov V. , McGuire G. 
Published: August 2008

AbstractSeveral properties and envisioned related applications in structural and functional composites of nanodiamond (ND) and their derivatives, onion‐like carbon (OLC) are reported. The electromagnetic radiation shielding properties of the OLC‐polyurethane composites had been characterized in the 120–165 GHz spectral range for 1–15 wt% OLC loading. It was also demonstrated that nanodiamond particles embedded to a polymer matrix attain photoluminescent properties when irradiated with a flux of MeV protons. This suggests an application of the ND‐polymer coatings as fluorescence‐induced indicators of a proton dose acquired by a spacecraft vehicle. Finally, we report on the fabrication of novel composites of carbon nanotubes incorporated into a nanodiamond matrix obtained by electrophoretic codeposition of these two strongest nanocarbon components. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Chemical and morphological aspects of diamond film oxidation and regeneration
Authors: Shpilman Z. , Gouzman I. , Grossman E. , Akhvlediani R. , Hoffman A. 
Published: August 2008

AbstractHot Filament – CVD diamond films with sub‐micron grain size have been exposed to atomic oxygen (AO) and annealed in ultra‐high vacuum at 700 °C. After oxidation, the surface was exposed in‐situ to thermally activated hydrogen or ex‐situ to hydrogen MW plasma in order to assess the surface regeneration mechanism. The morphological effects of hydrogen plasma were compared to the effects of oxygen plasma exposure. High Resolution Electron Energy Loss Spectroscopy (HREELS) was used to evaluate the surface bonding states, while tapping mode Atomic Force Microscopy (AFM) measurements were used to visualize surface morphology and to identify the preferential etching sites. Atomic oxygen exposure results in a very low erosion yield of the CVD diamond films, but significantly affects chemical composition of the upper surface layer. The main constituents of the surface after exposure to AO are saturated and unsaturated hydrocarbon species and oxygen‐bonded fragments. The diamond optical phonon (OP) overtones are absent indicating on a non‐diamond top layer. Gradual annealing and exposure to thermally activated hydrogen leads to a removal of hydrocarbons and oxygen containing species, and emergence of the diamond OP overtones. However, regeneration of diamond surface was not complete. On the other hand, the MW‐hydrogen treatment of the AO exposed sample fully regenerates chemical composition of diamond surface. Changes of the diamond surface morphology after exposure to AO are mild. The thermally activated hydrogen does not affect the surface morphology, while hydrogen MW plasma treatment severely damages the surface, resulting in selective etching of certain diamond facets. Oxygen plasma also leads to severe morphological damage, but in this case the damage was uniform, creating a dense granular phase on top of the diamond film. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Radiation detector performances of nitrogen doped HPHT diamond films
Authors: Schirru F. , Kupriyanov I. , Marczewska B. , Nowak T. 
Published: August 2008

AbstractThe remarkable physical properties of diamond such as tissue equivalence (atomic number Z = 6, close to that of human tissue), radiation and mechanical hardness and a wide band gap (5.5 eV) make it an ideal material for the fabrication of detectors for radiotherapy applications. However, the response to the radiation of such a kind of detector strongly depends on the bulk structure and in particular on the different impurities concentration inside the material.In the present paper we investigated the detector performances of two nitrogen doped HPHT synthetic diamonds grown at the IGM using a split‐sphere type high‐pressure apparatus. The samples were characterized using two different types of contacts: Au and Ti/Pt/Au configuration. The fabricated devices, studied as active detectors, presented totally different current response when they were exposed to the Co‐60 gamma irradiation. One sample in particular showed under irradiation strong value of current for which the photoconductive gain was found to be as high as 105. A model of trap‐induced sensitizing is suggested in order to explain the very high photoconductive gain obtained. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Dependence of CVD diamond growth rate on substrate orientation as a function of process parameters in the high microwave power density regime
Authors: Brinza O. , Achard J. , Silva F. , Bonnin X. , Barroy P. , Corte K. De , Gicquel A. 
Published: August 2008

AbstractThe use of diamond as a material for high power electronics requires high‐purity monocrystalline thick diamond films. Hence it is extremely important to have perfect control of the morphology during the entire growth process, so that the useable surface be maximized and residual stresses (which may cause cracking of the sample during the growth process) be limited. To assist in this work, a 3D geometric growth model has been recently developed, taking into account the growth rate of the different crystallographic planes: {100}, {110}, {111}, and {113}. The knowledge of the growth rate along the different directions as a function of growth parameters (substrate temperature, methane concentration, and nitrogen content in the gas phase) was the missing link between simulations and effective thick film processing. This knowledge is here embodied in the measurements displayed in this paper. In particular, we report on a way of limiting the occurrence of specific facets with deleterious effects on stress and crystal cracking probability. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effect of ECR etching conditions of (100)Ib diamond substrates on homoepitaxial low boron doped diamond layer quality
Authors: Volpe Pierre‐Nicolas , Muret Pierre , Omnes Franck 
Published: August 2008

AbstractThe effect of oxygen electron cyclotron resonance (ECR) microwave plasma etching on the crystallinity of low boron doped thin diamond films grown on Ib (100)‐oriented diamond substrates by MPCVD has been investigated with respect to the main experimental conditions: microwave power and O2 pressure at a constant DC bias. The substrates were exposed to ECR oxygen plasma to remove from 0.8 μm to 3.5 μm (depending on the value of the microwave power). The optimization of these two parameters has been performed in order to get the lowest surfaces roughness. This study aims also at demonstrating that oxygen ECR plasma etching is a powerful tool to remove surface and subsurface defects of diamond substrates as polishing grooves, subsurface damaged zone (polishing process induced defects) and various substrate roughness according to the observed growth sector. Low boron doped layers ([acceptors] = 4 × 1016 atoms/cm3) were grown by MPCVD on either O2 ECR plasma etched or merely chemically prepared (100) Ib diamond substrates. Cathodoluminescence analysis showed, for specific substrate etching conditions, a decrease of the band A emission (2.8 eV) in a low boron doped layer deposited on an etched substrate compared to a layer grown on a chemically prepared one. The FWHM of the FETO excitonic line of all theses layers is comprised between 16 meV and 13 meV for the best ones at 5 K. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Synthesis and characterisation of NCD films on 10 × 10 mm2 and deposition on 2 inch wafer using rotating substrate‐holder set‐up
Authors: Saada S. , Arnault J. C. , Rocha L. , Bazin B. , Bergonzo P. 
Published: August 2008

AbstractIn this study, we compare NCD films on 10 × 10 mm2 silicon substrates synthesised with high methane concentration and NCD films synthesised with prolongated bias during the growth step. Further, we performed in‐situ sequential XPS analysis (carbon binding state) using an UHV surface analysis system connected to the MPCVD reactor. AFM and HRSEM were used to characterize films morphology. Using the same substrate holder, NCD films have been deposited on silicon 2 in wafers. To improve the homogeneity, a rotating substrate‐holder set‐up enabling biasing and heating of the stage has been developed and coupled with computer control of the process for a better reproducibility. UV‐interferometry was performed to map the film thickness on 2 inches and quantify its thickness uniformity. Considering the symmetry of the system, AFM measurements were performed along the radius of the wafer to evaluate the surface homogeneity and its smoothness. The thickness uniformity of a NCD film of 1.6 µm deposited on 2 inch wafer is under 10% and the RMS roughness comprised between 13 and 14 nm. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A geometric confidence ellipse approach to the estimation of the ratio of two variables
Authors: Walter S. D. , Gafni A. , Birch S. 
Published: August 2008

AbstractOne is often interested in the ratio of two variables, for example in genetics, assessing drug effectiveness, and in health economics. In this paper, we derive an explicit geometric solution to the general problem of identifying the two tangents from an arbitrary external point to an ellipse. This solution permits numerical integration of a bivariate normal distribution over a wedge‐shaped region bounded by the tangents, which yields an evaluation of the tangent slopes as confidence limits on the ratio of the component variables. After suitable adjustment of the confidence coverage of the ellipse, these confidence limits are shown to be equivalent to those from Fieller's method. However, the geometric approach allows additional interpretation of the data through identification of the points of tangency, the ellipse itself, and expressions for the coverage probability of the confidence interval.Numerical evaluations using the theoretical expressions for the geometric confidence intervals (but ignoring sample variation in the underlying parameters) suggested that they perform well overall and are slightly conservative. Simulations that do take account of sample variation in the underlying parameters again suggested that the intervals perform well overall, although here they are slightly anti‐conservative. Coverage probabilities for the confidence intervals were only weakly dependent on the distance and correlation of the ellipse, but there were asymmetries in the failure rates of the upper and lower confidence limits in some configurations. The probability of no real solution existing was also evaluated. These ideas are illustrated by a practical example. Copyright © 2008 John Wiley & Sons, Ltd.
Very low CD19+ B‐lymphocyte percentage is associated with high levels of academic stress among healthy graduate students
Authors: McGregor Bonnie A. , Antoni Michael H. , Ceballos Rachel , Blomberg Bonnie B. 
Published: August 2008

AbstractElevated chronic psychological stress is associated with weakened immune response to vaccines. B‐lymphocyte development may provide a pathway by which psychological stress can weaken immune response to vaccines. The current study examined the effect of chronic psychological stress on B‐ and T‐lymphocytes among doctoral students, after their qualifying exams, and matched community controls. Blood was drawn from 10 doctoral students immediately after their 3‐day qualifying exams and from 10 age‐ and gender‐matched community controls. B‐ (CD19+) and T‐ (CD3+) lymphocyte percentages were enumerated with flow cytometry. Psychological stress was measured with the Perceived Stress Scale (PSS). The mean PSS score was higher for the graduate students compared with the control group (p< 0.01). Mean CD19+ lymphocyte percentage for the students (5.82 per cent) was dramatically lower than the control group (15.32 per cent,p< 0.0001). CD3+ lymphocyte percentage did not differ between the two groups. There was a significant negative correlation between CD19+ lymphocyte percentage and PSS score (r= −0.60,p= 0.003). Chronic psychological stress is associated with significant reductions in B‐lymphocytes among doctoral students undergoing qualifying exams and community participants. B‐lymphocyte decrements are a potential mechanism linking psychological stress and reduced antibody response to vaccines. Copyright © 2008 John Wiley & Sons, Ltd.