bluuebunny/crossref_metadata_2025 huggingface dataset:
Compositional control of poly(ethylene glycol) hydrogel modulus independent of mesh size
Authors: Browning M. B. , Wilems T. , Hahn M. , Cosgriff‐Hernandez E.
Published: May 2011

Poly(ethylene glycol) (PEG) hydrogels are of great interest in tissue engineering because of their established biocompatibility, high permeability, and tunable material properties. However, rational design of PEG hydrogel scaffold properties has been inhibited by the interdependence of key material properties such as modulus and mesh size. This study examined the effect of an acrylated 4‐arm PEG cross‐linker on gel modulus and mesh size as a means of inducing local increases in cross‐link density to decouple these two parameters. It was determined that adding the 4‐arm PEG cross‐linker to PEG hydrogels resulted in statistically significant increases in both tensile and compressive modulus while having minimal effects on overall gel mesh size. The incorporation of the 4‐arm PEG cross‐linker also broadened the range of achievable mechanical properties. This study provides the methodology to independently tune PEG hydrogel modulus and mesh size, which may be utilized in future investigations of the individual and combined effects of PEG hydrogel modulus and mesh size on cell behavior and viability. It also presents a more finely tunable hydrogel scaffold with utility in a broad range of tissue engineering applications. © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 2011.
Immobilization of Ag nanoparticles/FGF‐2 on a modified titanium implant surface and improved human gingival fibroblasts behavior
Authors: Ma Qianli , Mei Shenglin , Ji Kun , Zhang Yumei , Chu Paul K.
Published: May 2011

The objective of this study was to form a rapid and firm soft tissue sealing around dental implants that resists bacterial invasion. We present a novel approach to modify Ti surface by immobilizing Ag nanoparticles/FGF‐2 compound bioactive factors onto a titania nanotubular surface. The titanium samples were anodized to form vertically organized TiO2nanotube arrays and Ag nanoparticles were electrodeposited onto the nanotubular surface, on which FGF‐2 was immobilized with repeated lyophilization. A uniform distribution of Ag nanoparticles/FGF‐2 was observed on the TiO2nanotubular surface. The L929 cell line was used for cytotoxicity assessment. Human gingival fibroblasts (HGFs) were cultured on the modified surface for cytocompatibility determination. The Ag/FGF‐2 immobilized samples displayed excellent cytocompatibility, negligible cytotoxicity, and enhanced HGF functions such as cell attachment, proliferation, and ECM‐related gene expression. The Ag nanoparticles also exhibit some bioactivity. In conclusion, this modified TiO2nanotubular surface has a large potential for use in dental implant abutment. © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 2011.
Understanding the impact of divalent cation substitution on hydroxyapatite: An in vitro multiparametric study on biocompatibility
Authors: de Lima Ingrid Russoni , Alves Gutemberg Gomes , Soriano Carlos Alberto , Campaneli Ana Paula , Gasparoto Thais Helena , Schnaider Ramos Erivan , de Sena Lídia Ágata , Rossi Alexandre Malta , Granjeiro José Mauro
Published: May 2011

Hydroxyapatite (HA), a stable and biocompatible material for bone tissue therapy, may present a variable stoichiometry and accept a large number of cationic substitutions. Such substitutions may modify the chemical activity of HA surface, with possible impact on biocompatibility. In this work, we assessed the effects of calcium substitution with diverse divalent cations (Pb2+, Sr2+, Co2+, Zn2+, Fe2+, Cu2+, or Mg2+) on the biological behavior of HA. Physicochemical analyses revealed that apatite characteristics related to crystallinity and calcium dissolution/uptake rates are very sensitive to the nature of cationic substitution. Cytocompatibility was evaluated by mitochondrial activity, membrane integrity, cell density, proapoptotic potential, and adhesion tests. With the exception of Zn‐HA, all the substituted HAs induced some level of apoptosis. The highest apoptosis levels were observed for Mg‐HA and Co‐HA. Cu‐HA was the only material to impair simultaneously mitochondrial activity, membrane integrity, and cell density. The highest relative cell densities after exposure to the modified HAs were observed for Mg‐HA and Zn‐HA, while Co‐HA significantly improved cell adhesion onto HA surface. These results show that changes on surface dissolution caused by cationic substitution, as well as the increase of metal species released to biological media, were the main responsible factors related to alterations on HA biocompatibility. © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 2011.
Recurring extracorporeal circuit clotting during continuous renal replacement therapy resolved after single‐session therapeutic plasma exchange
Authors: Fülöp Tibor , Cosmin Adrian , Juncos Luis A.
Published: May 2011

We report a case of a 17‐year‐old white male with multiple fractures and multiorgan failure who developed oliguric acute renal failure requiring continuous renal replacement therapy. Repeated clotting of the extracorporeal circuit (ECC) prevented delivery of a minimally acceptable dose of renal replacement therapy despite adequate anticoagulation and dialysis catheter exchanges. Evaluation for a primary hypercoagulable state was negative, but his fibrinogen was elevated (1,320 mg/dL, normal range: 150–400 mg/dL), which is likely induced by his severe inflammatory state. A single session of therapeutic plasma exchange (TPE) with albumin and normal saline replacement was performed with subsequent drop in fibrinogen to 615 mg/dL. No further episodes of premature ECC clotting occurred, suggesting plasma factor(s) removed may have contributed to the clinical hypercoagulable state. TPE may play an adjunctive role in select cases of recurrent ECC clotting refractory to current anticoagulation techniques. © 2011 Wiley‐Liss, Inc.
Molecular chaperones as therapeutic targets to counteract proteostasis defects
Authors: Cattaneo Monica , Dominici Roberto , Cardano Marina , Diaferia Giuseppe , Rovida Ermanna , Biunno Ida
Published: May 2011

The health of cells is preserved by the levels and correct folding states of the proteome, which is generated and maintained by the proteostasis network, an integrated biological system consisting of several cytoprotective and degradative pathways. Indeed, the health conditions of the proteostasis network is a fundamental prerequisite to life as the inability to cope with the mismanagement of protein folding arising from genetic, epigenetic, and micro‐environment stress appears to trigger a whole spectrum of unrelated diseases. Here we describe the potential functional role of the proteostasis network in tumor biology and in conformational diseases debating on how the signaling branches of this biological system may be manipulated to develop more efficacious and selective therapeutic strategies. We discuss the dual strategy of these processes in modulating the folding activity of molecular chaperones in order to counteract the antithetic proteostasis deficiencies occurring in cancer and loss/gain of function diseases. Finally, we provide perspectives on how to improve the outcome of these disorders by taking advantage of proteostasis modeling. J. Cell. Physiol. 227: 1226–1234, 2012. © 2011 Wiley Periodicals, Inc.
Adaptive‐weighted cubic B‐spline using lookup tables for fast and efficient axial resampling of 3D confocal microscopy images
Authors: Indhumathi C. , Cai Y.Y. , Guan Y.Q. , Opas M. , Zheng J.
Published: May 2011

Confocal laser scanning microscopy has become a most powerful tool to visualize and analyze the dynamic behavior of cellular molecules. Photobleaching of fluorochromes is a major problem with confocal image acquisition that will lead to intensity attenuation. Photobleaching effect can be reduced by optimizing the collection efficiency of the confocal image by fast z‐scanning. However, such images suffer from distortions, particularly in the z dimension, which causes disparities in the x, y, and z directions of the voxels with the original image stacks. As a result, reliable segmentation and feature extraction of these images may be difficult or even impossible. Image interpolation is especially needed for the correction of undersampling artifact in the axial plane of three‐dimensional images generated by a confocal microscope to obtain cubic voxels. In this work, we present an adaptive cubic B‐spline‐based interpolation with the aid of lookup tables by deriving adaptive weights based on local gradients for the sampling nodes in the interpolation formulae. Thus, the proposed method enhances the axial resolution of confocal images by improving the accuracy of the interpolated value simultaneously with great reduction in computational cost. Numerical experimental results confirm the effectiveness of the proposed interpolation approach and demonstrate its superiority both in terms of accuracy and speed compared to other interpolation algorithms. Microsc. Res. Tech., 2012. © 2011 Wiley Periodicals, Inc.
Morphological alterations in the prostate stroma of rats submitted to chronic nicotine treatment
Authors: Carvalho Cesar Alexandre Fabrega , Pissolato Mariana , Candido Eduardo Marcelo , Liberti Edson Aparecido , Cagnon Valéria Helena Alves
Published: May 2011

The stroma plays a fundamental role in the function of different glandular systems. In the prostate, the stroma is responsible for the development and maintenance of the differentiated state of the epithelium. Nicotine induces tobacco dependence and promotes morphological alterations in the epithelial compartment. However, its effects on the prostate stroma are unclear. The objective of this study was to evaluate the morphology of the stromal microenvironment in the ventral prostate lobe of rats submitted to chronic nicotine administration. Twenty rats (Rattus norvegicus) were divided into two groups: 10 animals received subcutaneous nicotine and 10 animals received physiological saline by the same route. After treatment, samples were collected from the ventral prostate lobe, processed and submitted to histology, histochemistry, and ultrastructural analysis by transmission and scanning electron microscopy. The level of circulating testosterone was also analyzed. The results showed a significant increase in the density of type I collagen (56.3% to 85.9%, P < 0.01) and a decrease in the density of type III collagen (43.7% to 14.1%, P < 0.01). In addition, there was a qualitative increase in elastic fibers and in the number of smooth muscle cells with a secretory phenotype. Circulating testosterone levels were significantly reduced (898.3 to 363.1 ng/mL, P < 0.01). The results showed that nicotine modifies different components of the prostate stroma, suggesting that this drug is a risk factor for morphofunctional alterations in the prostate gland. Microsc. Res. Tech. 2012. © 2011 Wiley Periodicals, Inc.
Development of a new open‐tubular capillary electrochromatography method for in vitro monitoring of toxic aromatic amines distribution in rat blood
Authors: Shen Ying , Qi Li , Qin Jianglei , Zhang Haizhi , Qiao Juan , Chen Yongming , Mao Lanqun
Published: May 2011

Exposure to aromatic amines from different industrial and agricultural activities entails a substantial risk of deleterious somatic effects, genetic damage and cancer development. Thus, a new and simple method for separation and analysis of aromatic amines has been developed by open‐tubular capillary electrochromatography with a novel amphipathic block copolymer (poly(tert‐butyl acrylate)127‐block‐poly(glycidyl methacrylate)86) coating based on its self‐assembled property. Key factors affecting the separation efficiency of the test analytes, such as pH, buffer concentration and selective solvent, were studied in detail. Meanwhile, method validation was well evaluated by linearity (≥0.998), detection limit and recovery. Application of this developed protocol on in vitro monitoring of the target aromatic amines distribution in rat blood demonstrated its potential usage for separation and determination of aromatic amines in biological samples. Additionally, for assimilating more polymeric materials into analysis of aromatic amines, the effect of morphology changes of the amphipathic block copolymer coating on open‐tubular capillary electrochromatography separation was also studied, and the result revealed that the block copolymer coating could play the same role as surfactant.
Noise normalisation in capillary electrophoresis using a diode array detector
Authors: Erny Guillaume L. , Calisto Vania , Esteves Valdemar I.
Published: May 2011

When using capillary electrophoresis with a diode array detector, the wavelength at maximum absorbance is often chosen to quantify a given analyte. However, the background noise for every wavelength should be taken into account as it is by maximising the signal to noise ratio that the lowest limit of detection will be obtained. Here, we proposed an algorithm allowing to correct an electropherogram from its background absorption and to estimate the background noise. Applying it to all the electropherograms obtained in each wavelength channel allows obtaining the background noise as a function of the wavelength, which can be used to calculate the signal to noise ratio. This not only allows selecting the best wavelength to maximise the limit of detection of a given analyte, but also to generate a noise normalised base peak electropherogram (nn‐BPE). It is shown that the noise normalised base peak electropherograms substantially improve the peaks visualisation. The algorithm is part of a graphic user interface that runs under MatLab environment; it does not require any programming knowledge and is freely available.
Risky business: Trauma exposure and rate of posttraumatic stress disorder in African American children and adolescents
Authors: Hunt Kristin L. , Martens Patricia M. , Belcher Harolyn M.E.
Published: May 2011

Demographics, parental risk factors, and experiencing interpersonal trauma (domestic violence, community violence, and physical and sexual abuse) are related to childhood posttraumatic stress disorder (PTSD). Little is known about these factors and the risk of PTSD in African American children. This study examined associations between PTSD symptoms and gender, age, parent mental illness, parent substance abuse, and interpersonal trauma in African American children. Participants were 257 children and adolescents, ages 8–17 years (M = 11.7, SD = 2.5), who received outpatient mental health treatment. Being female and witnessing domestic violence was associated with more PTSD symptoms. Exposure to community violence and physical abuse increased the odds of clinically significant PTSD symptomatology by more than 2 times. The rate of PTSD (16%) was lower in the current study than in other same‐age study populations (25%–40%). Risk factors and identification strategies for PTSD are discussed.
Influence of anionic and nonionic micelles upon hydrolysis of 3‐hydroxy‐carbofuran
Authors: Astray G. , Cid A. , Manso J. A. , Mejuto J. C. , Moldes O. , Morales J.
Published: May 2011

The effect of nonionic and anionic micelles upon the stability of 3‐hydroxy‐carbofuran in basic media has been studied. The presence of micelles in the reaction medium implies a large inhibition of the basic hydrolysis of 3‐hydroxy‐carbofuran, due to the association of 3‐hydroxy‐carbofuran with the micellar core. The kinetic constants for the basic hydrolysis in these microheterogeneous media have been obtained on the basis of a micellar pseudophase model. © 2011 Wiley Periodicals, Inc. Int J Chem Kinet 43: 402–408, 2011
A novel mutation of gap junction protein beta 1 gene in x‐linked charcot–marie–tooth disease
Authors: Chen Sheng Dong , Li Zheng Xi , Guan Yang Tai , Zhou Xia Jun , Jiang Jian Ming , Hao Yong
Published: May 2011

Introduction: In this study we report a novel mutation in the gap junction protein beta 1 (GJB1) gene of a Chinese X‐linked Charcot–Marie–Tooth disease (CMTX1) family, which has specific electrophysiological characteristics. Methods: Twenty members in the family were studied by clinical neurological examination and GJB1 gene mutation analysis, and 3 patients were studied electrophysiologically. The proband and his mother also underwent sural nerve biopsy. Results: All patients have the CMT phenotype, except for 2 asymptomatic carriers. Electrophysiological examinations showed non‐uniform slowing of motor conduction velocities and partial motor conduction blocks and temporal dispersion. Sural nerve biopsy confirmed a predominantly demyelinating neuropathy, and an Asn2Lys mutation in the amino‐terminal domain was found in 9 members of this family, but not in 25 normal controls in the family. Conclusions: This family represents a novel mutation in the GJB1 form of CMTX1. The mutation in the amino‐terminus has an impact on the electrophysiological characteristics of the disease. Muscle Nerve, 2011
Effects of body orientation on maximum voluntary arm torques
Authors: Krainak Daniel M. , Ellis Michael D. , Bury Kathryn , Churchill Steven , Pavlovics Elynnor , Pearson Laura , Shah Miti , Dewald Julius P.A.
Published: May 2011

Introduction: Increased reliance on bulbospinal motor systems has been implicated in individuals with chronic stroke during maximum voluntary arm joint torque generation. Methods: Maximum isometric single‐joint and multi‐joint arm strength was observed in two body orientations (sitting and supine) while maintaining identical head/neck/trunk/extremity joint configurations in order to identify bulbospinal contributions to maximum joint torque generation in 11 individuals with stroke and 10 individuals without stroke. Results: During sitting, shoulder flexion was greater for both groups, whereas shoulder extension and elbow flexion, part of the “flexion synergy,” were greater only in individuals with stroke. Conclusions: Body orientation influenced isometric arm strength, notably the constituents of flexion synergy in individuals with stroke, suggesting bulbospinal motor pathway involvement. From a practical perspective, clinical evaluation of single joint strength in the supine position may underestimate strength available during activities of daily living that are performed in an upright orientation. Muscle Nerve, 2011
Nationwide register‐based surveillance system on drugs and pregnancy in Finland 1996–2006
Authors: Artama Miia , Gissler Mika , Malm Heli , Ritvanen Annukka
Published: May 2011

Purpose

The aim of this population‐based nationwide drugs and pregnancy surveillance system was to get basic information on the use of prescribed drugs during pregnancy and to achieve more detailed information on drug exposure–outcome associations with data obtained from the Finnish national health registers.

Methods

The data are based on information on all pregnancies ending in births (n = 632 629) or termination of pregnancy (TOP) (n = 117 255) in Finland between 1996 and 2006. The data containing information on maternal background factors, chronic diseases and drug purchases during pregnancy, born children, induced abortions, perinatal health and major congenital malformations were obtained from the Finnish national health registers. Information from the different registers was merged through record linkages based on unique personal identification numbers. Statistical analyses were conducted between the exposed and unexposed for individual drugs or Anatomical Therapeutic Chemical (ATC) classification drug groups in multivariate logistic regression including potential confounding factors.

Results

Nearly half of parturients and almost every third woman with TOP purchased drugs at least once 1 month prior to pregnancy and/or during pregnancy. The most frequent chronic diseases during pregnancy were asthma, hypothyroidism, epilepsy, rheumatoid arthritis and diabetes. Previously known causal connections between maternal chronic diseases and/or medication and perinatal health risks were already seen in the ATC‐group‐level analysis.

Conclusions

Comprehensive and detailed information for pharmacoepidemiological research on the effects of drug use during pregnancy in a cohort setting is possible with long‐term and cumulative data collection. Copyright © 2011 John Wiley & Sons, Ltd.
Effect of tackifiers on mechanical and dynamic properties of carbon‐black‐filled NR vulcanizates
Authors: Thaijaroen W.
Published: May 2011

This work focuses on the effect of tackifiers on mechanical and dynamic properties of carbon‐black‐filled vulcanizates. Three types of tackifiers with difference in softening points are selected for study including petroleum resin, phenolic resin, and gum rosin. The effect of tackifiers on the retardation of vulcanization is observed and the changes in mechanical properties due to the reduction in crosslink density are correlated. Good compatibility between natural rubber and all three tackifiers is verified by a single tan‐delta peak detected for each vulcanizate in temperature ramp test. A similar behavior to the Payne effect which usually found in the case of particulate‐filled rubbers is observed for the tackifier‐filled counterparts. The variation of temperature plays a crucial role in the dynamic behavior of tackified vulcanizates since the state of tackifiers determines its function during dynamic straining. As temperature passed through the softening point of a particular tackifier, substantial reduction in elastic response is observed; however, its relative damping to the untackified may still be maintained. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers.
Antireflection and light trapping of subwavelength surface structures formed by colloidal lithography on thin film solar cells
Authors: Tseng Ping‐Chen , Tsai Min‐An , Yu Peichen , Kuo Hao‐Chung
Published: May 2011

In this paper, we present a novel design of a surface nanostructure that suppresses the reflectivity and provides forward diffraction for light trapping. The structure under study comprises periodic nanoislands fabricated using self‐assembly polystyrene spheres, which are applicable to large‐area fabrication. We also show preliminary fabrication results of the proposed structure. The periodic nanoislands reduce the reflectivity through gradient effective refractive indices and enhance light trapping through diffraction in a periodic structure. We first systematically study the antireflection and light trapping effects using a rigorous coupled‐wave analysis and then calculate the short‐circuit current density of a 2‐μm‐thick crystalline silicon with periodic nanoislands and an aluminum back reflector. The optimum short‐circuit current density with periodic nanoislands achieves 25 mA/cm2 theoretically, which shows a 76.9% enhancement compared with that of bare silicon. Moreover, the structure also provides superior photocurrent densities at large angles of incidence, compared with conventional antireflection coatings. Copyright © 2011 John Wiley & Sons, Ltd.
Molecular dynamics simulations of PNIPAM‐co‐PEGMA copolymer hydrophilic to hydrophobic transition in NaCl solution
Authors: Du Hongbo , Qian Xianghong
Published: May 2011

Classical molecular dynamics simulations were carried out to investigate the hydrophilic to hydrophobic transition of PNIPAM‐co‐PEGMA close to its lower critical solution temperature (LCST) in 1 M NaCl solution. PNIPAM‐co‐PEGMA is a copolymer of poly(N‐isopropylacrylamide) (PNIPAM) and poly(ethylene glycol) methacrylate (PEGMA). The copolymer consists of 38 monomer units of NIPAM with two PEGMA chains attached to the PNIAPM backbone. The PNIPAM‐co‐PEGMA was observed to go through the hydrophilic−hydrophobic conformational change for simulations at temperature slightly above its LCST. Na+ ions were found to bind strongly and directly with amide O, even more strongly with the O atoms on PEGAMS chains, whereas Cl− ions only exhibit weak interaction with the polymer. Significantly a novel caged stable metal‐organic complex involving a Na+ ion coordinated by six O atoms from the copolymer was observed after the PNIPAM‐co‐PEGMA copolymer went through conformational transition to form a hydrophobic folded structure. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2011
Band gap bowings and anomalous pressure effects in III–V nitride alloys: Role of In‐segregation
Authors: Gorczyca I. , Suski T. , Christensen N. E. , Svane A.
Published: May 2011

Using ab initio calculations a comparison between InxGa1−xN, InxAl1−xN and GaxAl1−xN is performed to examine the role of indium in nitride alloys. The band gap, Eg, as well as its pressure coefficient, dEg/dp, are studied as functions of chemical composition, x. Following theoretical and experimental suggestions about the crucial role of In‐segregation in InxGa1−xN and InxAl1−xN, different arrangements of In atoms, uniform and clustered are considered. The presence of In and its clustering introduces a significant reduction of both Eg and dEg/dp, as well as strong bowings. These effects are most pronounced in InxAl1−xN, (with x = 0.25) and depend strongly on clustering geometry. It is shown that the In–N bonds are shortened when more than one In‐cation is bound to one nitrogen anion. The strong hybridization of wave functions (In‐p,d‐states and N‐p‐states) at the top of the valence band is responsible for the enhancements of bowings in the case of clustered distribution of indium atoms.
Nanometer to micron scale mechanics of [100] silicon nanowires using atomistic simulations at accelerated time steps
Authors: Kim Hansung , Tomar Vikas
Published: May 2011

Atomistic simulations have a unique capability to reveal the material deformation mechanisms and the corresponding deformation‐based constitutive behavior. However, atomistic simulations are limited by the accessible length and time scales. In the present work an equivalent crystal lattice method is used to perform mechanical deformation atomistic simulations of nanometer to micrometer sized silicon (Si) nanowires at accelerated time steps. The equivalent crystal lattice method's validity is verified by comparing the method's results with the results of classical molecular dynamics (MD) simulations at MD strain rates. The simulations predict that when the nanowire cross‐sectional size exceeds 50 nm, the dependence of the nanowire Young's moduli values on the changes in nanowire cross‐sectional size is considerably reduced. Analyses show a transition in nanowire failure mechanism from being ductile to being brittle with increase in the nanowire cross‐sectional size. Examinations of the surface effect reveal that below a critical surface to volume ratio value of 0.05 nm−1, the peak nanowire strength is independent of further reduction in the surface to volume ratio value. This finding places a size limit on the surface effect observed in Si nanowires.
Implantation of single crystalline iron garnet thin films with He+, B+, and Si+ ions
Authors: Ostafiychuk B. K. , Fedoriv V. D. , Yaremiy I. P. , Garpul O. Z. , Kurovets V. V. , Yaremiy I. C.
Published: May 2011

The mechanisms of defect formation in single crystalline epitaxial iron garnet thin films implanted with intermediate energy He+, B+, and Si+ ions have been investigated. X‐ray diffraction and modeling of the implantation process are used to show the effectiveness of defect formation from the electronic energy losses of ion implants decelerating in the target. High temperature diffractometry demonstrates the existence of two centers of disorder in the crystal lattices of ion‐implanted thin films: one due to the defect formation from the electronic energy losses and the other – from the nuclear energy losses of the implant ions.
Theoretical study of the band gap of SrS in GW approximation
Authors: Zhu Xiao‐Ling , Zhang Hong , Chen Gang , Cheng Xin‐Lu
Published: May 2011

Using the first‐principles pseudopotential method within a local density approximation of the density functional theory (DFT), the structural, electronic properties of SrS in the NaCl(B1) and CsCl(B2) structures have been studied. The calculated lattice parameters, bulk modulus and elastic constants are in excellent agreement with the experiment value and other theoretical value, whereas the minimum gap error is as high as 50.46% in the B1 structure. To get the reliable band gap values of the B1 structure, we employ the GW (G is Green's function and W is the screened Coulomb interaction) approximation method. The result in GW approximation improves the band gap value of the B1 structure greatly and agrees with the value of experimental measurement. And we also predict the band gap value of the B2 structure reliably by GW approximation.
Thermal wave propagation in thin films on substrate: the time‐harmonic thermal transfer function
Authors: Straube Hilmar , Breitenstein Otwin , Wagner Jan‐Martin
Published: May 2011

We present an analytical description of thermal wave propagation for cylindrical symmetry based on a transfer function concept which is analogous to optics. This concept leads to a general criterion for the spatial resolution and to computational benefits. It is applied to a medium consisting of a thermally thin layer of highly heat conductive material on a finite substrate. The result is then specialized to the two cases of highly heat conductive layer on quasi‐infinite substrate and finite substrate with no additional layer. This completes the theory of heat propagation between the thermally thick and thermally thin cases. We encounter the mathematical necessity to revise the definition of the latter terms, taking into account the lateral modulation of the thermal signal. The derived expressions are verified experimentally using infrared lock‐in thermography.
Large hidden orbital moments in magnetite
Authors: Goering Eberhard
Published: May 2011

The orbital magnetic moments in magnetite have recently been discussed with strong controversy. Here, the presence of orbital moments has been revealed by the independent analysis of the Fe L2,3 edge X‐ray absorption spectroscopy (XAS) spectra, a moment analysis fit of the Fe L2,3 edge X‐ray magnetic circular dichroism (XMCD), and by the comparison with O K edge XMCD. These orbital moments are located at the A and B sites of magnetite and aligned antiparallel with each other, similar to the spin moments. They also cancel each other and are not observable by methods averaging over the whole unit cell. These findings have strong implications for the understanding of the A and B site valence states, because the existence of orbital moments is also an indicator for the half‐metallic character of magnetite.
Trivalent Er and Sm ions in fluorochlorozirconate glasses: optical properties and X‐ray luminescence
Authors: Koughia Cyril , Belev George , Soundararajan Gokulakrishnan , Okada Go , Tonchev Dancho , Edgar Andy , Varoy Christopher R. , von Seggern Heinz , Kasap Safa
Published: May 2011

The optical properties and X‐ray luminescence of fluorochlorozirconate glasses and glass‐ceramics with composition 53% ZrF4, 20% NaF, 3% AlF3, 3% LaF3, 1% SmF3, (20‐ x)% BaF2 and x% BaCl2 with x varying from 0% to 19% and doped by the addition of ErCl3 or SmF3 have been investigated. The glasses show absorption and emission bands typical for trivalent Er3+ and Sm3+ ions. The samples doped with Sm showed X‐ray stimulated luminescence while those doped with Er gave no response. The annealing of samples at temperatures 250‐290 °C increases the X‐ray stimulated luminescence while there were no changes in optical absorption and photoluminescence. The observed effects are explained in terms of changes in the host glass and the enhancement of excitation transfer from the glass to embedded Sm3+ ions (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Photoinduced mass transfer in amorphous As2S3 films
Authors: Teteris Janis , Gertners Ugis , Reinfelde Mara
Published: May 2011

The surface relief grating formation in amorphous As2S3 films strongly depends on the polarization state of recording beams. The surface relief grating formation efficiency of s‐s and p‐p recording beam combination can be essentially enhanced by additional illumination with orthogonal polarization. It is shown that the direction of mass transport on the film surface is determined by the direction of light electric vector (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Spectroscopy and structural properties of amorphous and nanocrystalline silicon carbide thin films
Authors: Halindintwali Sylvain , Knoesen D. , Julies B. A. , Arendse C. J. , Muller T. , Gengler Régis Y. N. , Rudolf P. , van Loosdrecht P. H. M.
Published: May 2011

Amorphous SiC:H thin films were grown by hot wire chemical vapour deposition from a SiH4/CH4/H2 mixture at a substrate temperature below 400 °C. Thermal annealing in an argon environment up to 900 °C shows that the films crystallize as μc‐Si:H and SiC with a porous microstructure that favours an oxidation process. By a combination of spectroscopic tools comprising Fourier transform infrared, Raman scattering and X‐rays photoelectron spectroscopy we show that the films evolve from the amorphous SiHx/SiCH2 structure to nanocrystalline Si and SiC upon annealing at a temperature of 900 °C. A strong RT photoluminescence peak of similar shape has been observed at around 420 nm in both as‐deposited and annealed samples. Time‐resolved luminescence measurements reveal that this peak is fast decaying with lifetimes ranging from 0.5 to ∼1.1 ns. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optical properties of multilayer silicon nitride structures with silicon quantum dots
Authors: Lipiński Marek , Jaglarz Janusz , Chrzanowska Agnieszka , Hejduk Krzysztof
Published: May 2011

In our study we report the investigation of nanostructures embedded in silicon nitride films deposited by RF plasma enhanced chemical vapor deposition (PECVD). The multilayer structure consisting of fifty near‐stoichiometric silicon nitride layers followed by silicon–rich silicon nitride layers has been deposited and heated in 1100 °C in order to realize the quantum dot superlattice. The properties of the quantum dots are investigated using high resolution transmission electron microscopy (HRTEM) and spectroscopic ellipsometry. It has been observed that after annealing the photoluminescence that was previously observed in the sample is strongly suppressed. At the same time a new absorption peak in the dispersion of the extinction coefficient occurred almost at the same value of the wavelength. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Developmental exposure to decabrominated diphenyl ether (BDE‐209): Effects on sperm oxidative stress and chromatin dna damage in mouse offspring
Authors: Tseng Li‐Ho , Hsu Ping‐Chi , Lee Chia‐Wei , Tsai Shinn‐Shyong , Pan Min‐Hsiung , Li Mei‐Hui
Published: May 2011

Polybrominated diphenyl ethers (PBDEs) are used as brominated flame retardants and have been found in human milk in recent years. This study investigates whether prenatal exposure to decabrominated diphenyl ether (BDE‐209) induces sperm dysfunction in male offspring. Pregnant CD‐1 mice were gavaged once daily with corn oil (control), 10, 500, and 1500 mg kg−1 body weight of BDE‐209 from day 0 of gestation to day 17. The outcomes of male reproductive parameters were assessed on postnatal day 71. Anogenital distance, sperm‐head abnormalities, and testicular histopathology were significantly affected in male offspring prenatally exposed to 1500 mg kg−1. Significant increases in the tendency for sperm DNA denaturation (αT) induction and the DNA fragmentation index (DFI) were found in those exposed to 10, 500, and 1500 mg kg−1 (P < 0.05). We observed a significant increase of sperm hydrogen peroxide (H2O2) generation in the 10 and 1500 mg/kg/day groups compared to the control group (P < 0.05). Although our findings suggested that the mechanisms underlying BDE‐209‐induced sperm DNA damage and H2O2 generation might not be represented as a dose‐response relationship, we found that the greater the excess production of sperm H2O2, the greater the sperm αT (r = 0.65, P = 0.0155) and DFI (r = 0.53, P = 0.002). In conclusion, developmental exposure to BDE‐209 induced sperm‐head abnormality, oxidative stress, chromatin DNA damage, and testicular histopathological changes. These findings suggest that BDE‐209‐induced male reproductive effects might involve the formation of sperm H2O2 which attacks nucleic acids via H2O2 generation. © 2011 Wiley Periodicals, Inc. Environ Toxicol, 2013.
Oxidation of Corn Oils with Spiked Tocols
Authors: Dolde David , Wang Tong
Published: May 2011

Stripped corn oils with added tocopherols and tocotrienols, at concentrations between 100 and 5,000 ppm, were used to evaluate antioxidant activity of these tocol compounds. The formation of lipid hydroperoxides, measured as peroxide value (PV), was accelerated at 60 °C in the dark for 5 days. Resistance to oxidation as induction period (IP) was also measured using an oxidative stability instrument (OSI) at 100 °C. For PV inhibition, the oils containing α‐tocols exhibited decreasing effectiveness with increasing concentration. At day five, samples with 100 ppm α‐tocols had the lowest PVs of about 40 mequiv/kg and samples containing 5,000 ppm had the highest values, ranging from 150 to 200 mequiv/kg. At concentrations above 700 ppm of α‐tocols, there was an inversion of antioxidative properties as α‐tocols promoted lipid oxidation. The opposite concentration effect was observed with δ‐tocols and γ‐tocotrienol (T3) for which antioxidant effectiveness increased with concentration. OSI‐IP hour at 100 °C increased with increasing tocol concentrations for all tocol homologs, although with diminishing effectiveness at greater than 700 ppm. The α‐tocols were less effective in extending the IP (~9 h at 5,000 ppm) than the δ‐tocols and γ‐T3 (13–14 h at 5,000 ppm). Therefore, the antioxidant or prooxidant activities of different tocols are different and the outcomes are different depending on the evaluation methods used.
Contrast-enhanced ultrasound of the spleen: an introduction and pictorial essay
Authors: Sutherland Tom , Temple Faye , Galvin Angela , Hennessy Oliver
Published: May 2011

A wide variety of pathologies can produce focal lesions within the spleen. These are being more frequently encountered as imaging technology improves. It is vital that radiologists are aware of these pathologies to enable accurate diagnosis. The role of ultrasound contrast in splenic disease will be discussed and illustrated with cases likely to be encountered by general and abdominal radiologists.
Histone tails: Directing the chromatin response to DNA damage
Authors: Greenberg Roger A.
Published: May 2011

Considerable energetic investment is devoted to altering large stretches of chromatin adjacent to DNA double strand breaks (DSBs). Immediately ensuing DSB formation, a myriad of histone modifications are elicited to create a platform for inducible and modular assembly of DNA repair protein complexes in the vicinity of the DNA lesion. This complex signaling network is critical to repair DNA damage and communicate with cellular processes that occur in cis and in trans to the genomic lesion. Failure to properly execute DNA damage inducible chromatin changes is associated with developmental abnormalities, immunodeficiency, and malignancy in humans and in genetically engineered mouse models. This review will discuss current knowledge of DNA damage responsive histone changes that occur in mammalian cells, highlighting their involvement in the maintenance of genome integrity.
Purchasing IPOs with Commissions
Authors: Goldstein Michael A. , Irvine Paul , Puckett Andy
Published: May 2011

We find direct evidence that institutions increase round-trip stock trades, increase average commissions per share, and pay unusually high commissions on some trades in order to send abnormally high commissions to the lead underwriters of profitable initial public offerings (IPOs). These excess commission payments are a particularly effective way for transient investors to receive lucrative IPO allocations. Our results suggest that the underwriter’s concern for their long-term client relationships limits the payment-for-IPO practice. We estimate that abnormal commission payments are large for the most profitable issues, and that an additional $1 excess commission payment to the lead underwriter results in $2.21 in investor profits from allocated shares.
Comparison of self-fields effects in two-stream electromagnetically pumped FEL with ion-channel guiding and axial magnetic field
Authors: SAVIZ S. , MEHDIAN H. , AGHAMIR FARZIN M. , GHORANNEVIS M. , ASHKARRAN A. A.
Published: May 2011

A theory of two-stream free-electron laser in a combined electromagnetic wiggler and an ion-channel guiding is developed. In the analysis, the electron trajectories and the small signal gain are derived by considering the effects of self-fields. Numerical calculations show that there are seven group's trajectories rather than nine groups reported in Mehdian and Saviz (2010 Chin. Phys. B 19(1), 014214). The comparison of the normalized gains and their corresponding normalized frequencies by employing the axial magnetic field and ion-channel guiding, with and without self-fields, in FEL has been studied numerically. The results show that the normalized maximum gain in FEL with axial magnetic is larger than that for using ion-channel guiding except in small region, but the results for their corresponding normalized frequencies are opposite.
The ‘routes’ and ‘roots’ ofdanzón: a critique of the history of a genre
Authors: Malcomson Hettie
Published: May 2011

In this article, I examine the history of a genre that spans several continents and several centuries. I bring together material from Mexico, Cuba, France and the UK to create anew, expand upon and critique the ‘standard’ histories of danzón narrated by Mexico's danzón experts (and others). In these ‘standard’ histories, origins and nationality are key to the constitution of genres which are racialised and moralised for political ends. Danzón, its antecedents and successors are treated as generic equivalents despite being quite different. From the danzón on, these genres are positioned as being the products of individual, male originators (and their nations). ‘Africa’ is treated as a conceptual nation, and ‘Africanness’ as something extra which racialises hegemonic European music-dance forms. Political leanings and strategies determine whether these music-dance forms are interpreted, adopted or co-opted as being ‘black’ or ‘white’.
The External Ion Microbeam of the LABEC Laboratory in Florence: Some Applications to Cultural Heritage
Authors: Calusi Silvia
Published: May 2011

Ion beam analysis (IBA) techniques are a powerful analytical tool used to investigate the composition and structure of precious materials principally because they can be applied in atmosphere. Thus, the sample can be analyzed as is, and heating and charging effects are strongly diminished. Since IBA measurements can be made with low ion currents and acquisition time, the damage risk is limited. At the microbeam line of the LABEC laboratory, it is possible to exploit the potentials of IBA techniques in an external set up to reconstruct the distribution maps of all the detected elements over the analyzed area with spatial resolutions as low as 10 μm. This is an important feature when objects with inhomogeneous structures—on a scale of hundred microns or so—are investigated, as happens in some cases with artworks. The detection set up installed on our external microbeam allows us to use different IBA techniques simultaneously. Thus, in a single measurement run, it is possible to obtain complementary information on both sample composition and structure. Some applications to works of art are presented here as examples of the analytical capabilities of the external scanning microbeam in the cultural heritage field.
The role of wildlife in transboundary animal diseases
Authors: Siembieda J. L. , Kock R. A. , McCracken T. A. , Newman S. H.
Published: May 2011

This paper identifies some of the more important diseases at the wildlife–livestock interface and the role wildlife plays in disease transmission. Domestic livestock, wildlife and humans share many similar pathogens. Pathogens of wild or domestic animal origin that can cause infections in humans are known as zoonotic organisms and the converse are termed as anthroponotic organisms. Seventy-seven percent of livestock pathogens and 91% of domestic carnivore pathogens are known to infect multiple hosts, including wildlife. Understanding this group of pathogens is critical to public health safety, because they infect a wide range of hosts and are most likely to emerge as novel causes of infection in humans and domestic animals. Diseases at the wildlife–livestock interface, particularly those that are zoonotic, must be an area of focus for public health programs and surveillance for emerging infectious diseases. Additionally, understanding wildlife and their role is a vital part of understanding the epidemiology and ecology of diseases. To do this, a multi-faceted approach combining capacity building and training, wildlife disease surveillance, wildlife–livestock interface and disease ecology studies, data and information sharing and outbreak investigation are needed.
Tinnitus: some thoughts about its origin
Authors: Eggermont J. J.
Published: May 2011

An auditory sensation follows generally as the result of the sequence stimulus, transduction, coding, transformation and sensation. This is then optionally followed by perception and a reaction. The stimulus is usually airborne sound causing movements of the tympanic membrane, the middle ear ossicles, the inner ear fluids and the basilar membrane. The movements of the basilar membrane are dependent on stimulus frequency: high frequency tones excite only the basal part of the cochlea, regardless of the stimulus intensity; low frequency tones at low levels only excite the so-called place specific region at the apical end but at high levels (above 60–70 dB SPL) cause appreciable movement of the entire basilar membrane. Basilar membrane tuning is as sharp as that of inner hair cells or auditory nerve fibers (Sellick et al., 1982) at least in the basal turn of animals that have a cochlea in physiologically impeccable condition.
Effects of electrical stimulation on tinnitus
Authors: House John W.
Published: May 2011

Our early experience with the use of cochlear implants indicated that chronic electrical stimulation to the inner ear tends to help tinnitus. For this reason we have been investigating the use of electrical stimulation as a treatment for the symptom of tinnitus.
Inflammatory ear disease and tinnitus
Authors: Ronis M.
Published: May 2011

Tinnitus, in most instances, is a symptom of a disease process which defies clear identification. The multiplicity of sites of origin and the mechanisms of production are truly a diagnostic and therapeutic dilemma. The clinician can, however, easily recognize the classic presentation of acute and chronic inflammatory disease.
Introduction
Authors: Shulman A.
Published: May 2011

We now come to our final session concerning treatment methods and results. We are very honoured to have with us here a number of internationally-distinguished individuals in various specialties, particularly otolaryngology. We now have the treatment session divided into three sections: one section for treatment that will control tinnitus by masking; the second for medical treatment; and the third for surgical treatment. I have selected moderators for each of these sections who are international in their experience as well as in their reputations. First, for the section on tinnitus masking, I have asked Mr John C. Ballantyne, of London, England, to chair the section. He is editor of the Journal of Laryngolgy and Otology. We are honoured to have him with us.