bluuebunny/crossref_metadata_2025 huggingface dataset:
Electromechanical response of 1–3 piezoelectric composites: Effect of fiber shape
Authors: Kar-Gupta R. , Marcheselli C. , Venkatesh T. A.
Published: July 2008

An analytical model and a finite element based numerical model is presented to study the effects of fiber shape on the complete elastic, dielectric, and piezoelectric properties of a general 1–3 long-fiber “longitudinal” and “transverse” composite with elastically anisotropic and piezoelectrically active constituents. Six classes of piezoelectric composites, each with several prismatic and nonprismatic shaped fibers, in two widely different ceramic and polymer matrices are considered. It is demonstrated that (i) while the longitudinal material properties are insensitive to changes in the shape of the fiber phase, the transverse properties display a strong dependence on the shape of the fiber phase, particularly for the polymer-matrix composites; (ii) while the figures of merit such as the longitudinal piezoelectric coupling constant and the acoustic impedance do not demonstrate significant fiber shape effects, the transverse sensing ability of the polymer-matrix transverse composite is significantly influenced by the fiber shape with the composites with prolate shaped fibers providing the highest piezoelectric voltage constant.
Ultrahigh temperature Bi3Ti0.96Sc0.02Ta0.02NbO9-based piezoelectric ceramics
Authors: Gai Zhi-Gang , Wang Jin-Feng , Sun Wen-bin , Wang Chun-Ming , Zhao Ming-Lei , Sun Shang-Qian , Ming Bao-Quan , Qi Peng , Zheng Li-mei , Du Juan , Zhang Shujun , Shrout Thomas R.
Published: July 2008

The effect of (Sc,Ta,Ce) doping on the properties of Bi3TiNbO9 (BTNO)-based ceramics was investigated. The cerium modification greatly improves the piezoelectric activity of Bi3(Ti0.96Sc0.02Ta0.02)NbO9-based ceramics and significantly decreases the dielectric dissipation. The d33 of Bi3Ti0.96Sc0.02Ta0.02NbO9+x wt %CeO2 (x=0.35) was found to be 18 pC/N, the highest value among the BTNO-based ceramics and almost three times as much as the reported d33 values of the pure BTNO ceramics (∼6 pC/N). The modification increased the resistivity ρ of the samples extremely, resolving the low resistivity problem for high temperature applications. The dielectric spectroscopy shows that the TC for all the ceramics is higher than 900 °C. The mechanical quality factor Q and planar coupling factors kp and kt of Bi3Ti0.96Sc0.02Ta0.02NbO9+0.35 wt %CeO2 ceramic were found to be 2835, 9%, and 23%, respectively, and it has high TC and stable piezoelectric properties, demonstrating that the (Sc,Ta,Ce) modified BTNO-based material is a wonderful candidate for high temperature applications.
Chaos at the border of criticality
Authors: Medvedev Georgi S. , Yoo Yun
Published: July 2008

The present paper points out a novel scenario for the formation of chaotic attractors in a class of models of excitable cell membranes near an Andronov–Hopf bifurcation (AHB). The mechanism underlying chaotic dynamics admits a simple and visual description in terms of the families of one-dimensional first-return maps, which are constructed using the combination of asymptotic and numerical techniques. The bifurcation structure of the continuous system (specifically, the proximity to a degenerate AHB) endows the Poincaré map with distinct qualitative features such as unimodality and the presence of the boundary layer, where the map is strongly expanding. This structure of the map in turn explains the bifurcation scenarios in the continuous system including chaotic mixed-mode oscillations near the border between the regions of sub- and supercritical AHB. The proposed mechanism yields the statistical properties of the mixed-mode oscillations in this regime. The statistics predicted by the analysis of the Poincaré map and those observed in the numerical experiments of the continuous system show a very good agreement.
Size dependent motion of nanodroplets on chemical steps
Authors: Moosavi A. , Rauscher M. , Dietrich S.
Published: July 2008

Nanodroplets on chemically structured substrates move under the action of disjoining pressure induced forces. A detailed analysis of them shows that, even in the absence of long-ranged lateral variations of the effective interface potential, already the fact that due to their small size nanodroplets do not sample the disjoining pressure at all distances from the substrate can lead to droplet motion toward the less wettable part of the substrate, i.e., in the direction opposite to the one expected on the basis of macroscopic wettability considerations.
Structural transition of hexagonal tube to rocksalt for (MgO)3n, 2≤n≤10
Authors: Dong Ruibin , Chen Xiaoshuang , Wang Xiaofang , Lu Wei
Published: July 2008

The structures of (MgO)3n (2≤n≤10) clusters are studied using density functional theory (DFT). The starting structures are generated from empirical genetic algorithm simulations. The lowest-energy structures of (MgO)3n are then obtained from a number of structural isomers by using DFT optimization. It is found that when n≤5 hexagonal tube is the most stable structure, and when n≥6 (except 7) the rocksaltlike structure is favored, which is the same as that of the bulk. The n=7 is an interesting case, where the structure again is the hexagonal tube as the most stable structure. However, from the second order difference of the average atomization energy, we find that the n=7 case is thermodynamically unstable with respect to disproportionation to the smaller and larger clusters. The result may be the reason that it is not observed in the experiment. Therefore, we can conclude that the geometry transition really takes place at n=6. The rocksalt is the most stable structure for a large range of n numbers, from the (MgO)3×6 cluster to bulk magnesium oxide. The result is different from Wilson’s previous prediction because of the use of the ionic potential.
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FePt-oxide columnar perpendicular media with high coercivity and small grain size
Authors: Yang En , Laughlin David E.
Published: July 2008

Perpendicular L10 ordered FePt-oxide two-phase thin films with an average grain size of ∼7nm were prepared by alternate sputtering of FePt and oxide at 475°C. Very uniform and well-isolated columnar grains were obtained with coercivity as high as 7kOe. It is found that the texture of thin films depends greatly on the thickness of FePt; SiO2 works better than MgO as the amorphous oxide, which provides for magnetic isolation of the FePt grains. The coercivity of the films rises with increasing grain size and thinner alternately sputtered single layers. Reducing the grain size to ∼2.9nm produces granular grains with a coercivity of 3.5kOe.
Spatially resolved residual stress assessments of GaN film on sapphire substrate by cathodoluminescence piezospectroscopy
Authors: Pezzotti Giuseppe , Porporati Alessandro Alan , Leto Andrea , Zhu Wenliang
Published: July 2008

Two cathodoluminescence piezospectroscopic (CL/PS) approaches for measuring the residual stress distribution in thin films are critically examined and compared using an intrinsic GaN film sample (2.5μm in thickness) grown on a (0001)-oriented sapphire substrate. The first approach invokes an analytical model to fit experimental stress distributions as retrieved in both film and substrate at the edge of an artificially created cross section of the sample. Such an edge-stress distribution takes into account both the thermal expansion mismatch between the film and substrate and the mechanistics of film growth process. In the second approach, we directly and nondestructively measure the bulk residual stress field from the sample top surface on the film side using an increase in electron beam voltage (maintaining a constant beam power) as a means for screening the film subsurface. In this latter case, the combined effects of self-absorption and misfit dislocations on the GaN spectrum severely affect the CL/PS assessments; therefore, they need to be analyzed separately from the effect of stress. After spectral deconvolution of the obtained stress profiles, according to either in-plane or in-depth response functions of the electron probe for both film and substrate, cross-section and top-surface stress data were compared and discussed in an effort to substantiate the feasibility of spatially resolved CL/PS approach for the examination of residual stress distributions in film structures.
Slim P-E hysteresis loop and anomalous dielectric response in sol-gel derived antiferroelectric PbZrO3 thin films
Authors: Parui Jayanta , Krupanidhi S. B.
Published: July 2008

Sol-gel derived PbZrO3 (PZ) thin films have been deposited on Pt(111)∕Ti∕SiO2∕Si substrate and according to the pseudotetragonal symmetry of PZ, the relatively preferred (110)t oriented phase formation has been noticed. The room temperature P-E hysteresis loops have been observed to be slim by nature. The slim hysteresis loops are attributed to the [110]t directional antiparallel lattice motion of Pb ions and by the directionality of the applied electric field. Pure PZ formation has been characterized by the dielectric phase transition at 235°C and antiferroelectric P-E hysteresis loops at room temperature. Dielectric response has been characterized within a frequency domain of 100Hz–1MHz at various temperatures ranging from 40to350°C. Though frequency dispersion of dielectric behaves like a Maxwell–Wagner type of relaxation, ω2 dependency of ac conductivity indicates that there must be G-C equivalent circuit dominance at high frequency. The presence of trap charges in PZ has been determined by Arrhenius plots of ac conductivity. The temperature dependent n (calculated from the universal power law of ac conductivity) values indicate an anomalous behavior of the trapped charges. This anomaly has been explained by strongly and weakly correlated potential wells of trapped charges and their behavior on thermal activation. The dominance of circuit∕circuits resembling Maxwell–Wagner type has been investigated by logarithmic Nyquist plots at various temperatures and it has been justified that the dielectric dispersion is not from the actual Maxwell–Wagner-type response.
Vacuum insulator development for the dielectric wall accelerator
Authors: Harris J. R. , Blackfield D. , Caporaso G. J. , Chen Y.-J. , Hawkins S. , Kendig M. , Poole B. , Sanders D. M. , Krogh M. , Managan J. E.
Published: July 2008

At Lawrence Livermore National Laboratory, we are developing a new type of accelerator, known as a dielectric wall accelerator, in which compact pulse-forming lines directly apply an accelerating field to the beam through an insulating vacuum boundary. The electrical strength of this insulator may define the maximum gradient achievable in these machines. To increase the system gradient, we use “high-gradient insulators” composed of alternating layers of dielectric and metal for the vacuum insulator. In this paper, we present our recent results from experiment and simulation, including successful testing of a high-gradient insulator in a functioning dielectric wall accelerator cell. Our results indicate that proper high-voltage conditioning of the insulators can delay the onset of flashover, that the observed conditioning consists of both a permanent and a temporary part, and that the insulators’ voltage-holding capability increases with increasing dielectric layer thickness.
Thermal stability of SrFeO3/Al2O3 thin films: Transmission electron microscopy study and conductometric sensing response
Authors: Wang Dashan , Tunney James J. , Du Xiaomei , Post Michael L. , Gauvin Raynald
Published: July 2008

The SrFeO3/Al2O3 thin film system has been studied using transmission electron microscopy (TEM). The thin films of SrFeO3 were grown by pulsed laser deposition onto single crystal and sintered polycrystalline Al2O3 substrates at room temperature (RT) and 700 °C and subjected to annealing for various periods of time at 700–1000 °C. TEM characterization showed that the morphology of the film varied with changes of deposition temperature. Films deposited at RT featured a columnar structure and those deposited at 700 °C showed layers with crystalline grains. The interfacial structures of the films remained unchanged below 700 °C. Interfacial reactions were observed following annealing at 850 °C for 5 h. The phase transformation at the interface was characterized for the film annealed at 1000 °C for 5 h, for which the principal phases were identified as SrAl2−xFexO4 and SrFe12−yAlyO19. Evaluation for thin film conductometric sensing applications indicated that the untreated films deposited at 700 °C onto both single crystal and sintered Al2O3 substrates exhibited a p-type gas sensor response to oxygen at 500 °C.
Approximation scheme for master equations: Variational approach to multivariate case
Authors: Ohkubo Jun
Published: July 2008

We study an approximation scheme based on a second quantization method for a chemical master equation. Small systems, such as cells, could not be studied by the traditional rate equation approach because fluctuation effects are very large in such small systems. Although a Fokker–Planck equation obtained by the system size expansion includes the fluctuation effects, it needs large computational costs for complicated chemical reaction systems. In addition, discrete characteristics of the original master equation are neglected in the system size expansion scheme. It has been shown that the use of the second quantization description and a variational method achieves tremendous reduction in the dimensionality of the master equation approximately, without loss of the discrete characteristics. Here, we propose a new scheme for the choice of variational functions, which is applicable to multivariate cases. It is revealed that the new scheme gives better numerical results than old ones and the computational cost increases only slightly.
The phase behavior of polyethylene ring chains
Authors: Su Jiaye , Zhang Linxi , Liang Haojun
Published: July 2008

The equilibrium properties of an isolated polyethylene ring chain are studied by using molecular dynamics (MD) simulations. The results of an 80-bond linear chain are also presented, which are in agreement with previous studies of square-well chains and Lennard-Jones (LJ) homopolymers. Mainly, we focus on the collapse of polyethylene ring chains. At high temperatures, a fully oblate structure is observed for the ring chains with different chain lengths. For such an oblate structure, a shape factor of ⟨δ*⟩=0.25 and a rodlike scaling relation between the radius of gyration and chain lengths could be deduced easily in theory, and the same results are obtained by our MD simulations. Such an oblate structure can be obtained by Monte Carlo simulation only for sufficient stiff ring chains. When the temperature decreases, an internal energy barrier is observed. This induces a strong peak in the heat capacity, denoting a gas-liquid-like transition. This energy barrier comes mainly from the local monomer-monomer interactions, i.e., the bond-stretching, the bond-bending, and the torsion potentials. A low temperature peak is also observed in the same heat capacity curve, representing a liquid-solid-like transition. These numerical simulation results support a two-stage collapse of polyethylene ring chains; however, the nature should be different from the square-well and LJ ring chains.
Evolution of valence-band alignment with nitrogen content in GaNAs∕GaAs single quantum wells
Authors: Shao Jun , Lu Wei , Sadeghi M. , Lü Xiang , Wang S. M. , Ma Lili , Larsson A.
Published: July 2008

We report on experimental evidence for the transition of valence-band alignment from type I to type II in GaNxAs1−x∕GaAs single quantum wells by photoreflectance measurements. The substitutional nitrogen content covers a range of 1.4%–5.9%. The turning point of the type I–type II transition occurs at x≳4.7%. The experimental observations can be well interpreted by a combination of band anticrossing model and model-solid theory when nonlinear behavior of either the shear deformation potential or the average valence-band energy is taken into account. The effect of dilute nitrogen on the valence-band offset of GaNAs∕GaAs quantum well structure is hence clarified.
Prompted hydrogenation of carbon nanotubes by doping light metals
Authors: Chen Bei , Li Baihai , Chen Liang
Published: July 2008

Dissociative chemisorption of H2 on the exterior wall of the (5,5) single-walled carbon nanotubes (SWCNTs) are examined using density functional theory. We show that the hydrogenation of SWCNTs can be promoted by doping light metals in the interior channel. Potassium and aluminum are identified as promising dopants, which can enhance the binding energies of H2 on the (5,5) SWCNTs by 0.5–0.7eV and reduce the H2 dissociation barriers by 0.7–1.0eV. A possible method to further improve the hydrogenation kinetics is discussed.
Crystallinity improvement of benzodithiophene-dimer films for organic field-effect transistors
Authors: Yamaguchi K. , Takamiya S. , Minami M. , Doge Y. , Nishide Y. , Osuga H. , Uno K. , Tanaka Ichiro
Published: July 2008

We have significantly improved the crystallinity of vacuum-evaporated benzodithiophene (BDT)-dimer films using pentacene crystallinity control layers. The pentacene molecules evaporated on hexamethyldisilazane-treated SiO2 surfaces first form many small islands. Then, the islands grow two dimensionally. We used thin pentacene films with surface coverage of approximately 90% as crystallinity control layers, and deposited 30-nm-thick BDT-dimer films on them. Micron-scale planar grains are observed in atomic force microscopy images of the BDT-dimer films. The highly anisotropic shape of the grains indicates that the BDT-dimer films of good crystallinity have been obtained. The field-effect transistors based on the BDT-dimer films showed excellent hole mobility of 1.2cm2V−1s−1 at maximum.
An optimal tunable Josephson element for quantum computing
Authors: Chiarello F. , Castellano M. G. , Torrioli G. , Poletto S. , Cosmelli C. , Carelli P. , Balashov D. V. , Khabipov M. I. , Zorin A. B.
Published: July 2008

We introduce a three-junction superconducting quantum interference device (SQUID) that can be used as an optimal tunable element in Josephson quantum computing applications. This device can replace the simple dc SQUID generally used as a tunable element in this kind of applications, with a series of advantages concerning the coherence time and the tolerance to small errors. We study the device both theoretically and experimentally at 4.2K, obtaining a good agreement between the results.
Giant effective g-factor in PbxEu1−xTe epitaxial films
Authors: Heredia E. , de Oliveira Rappl P. H. , Motisuke P. , Gazoto A. L. , Iikawa F. , Brasil M. J. S. P.
Published: July 2008

We investigated PbxEu1−xTe films with x⩽0.2 by magneto-optical measurements. For x∼0.01, the optical emission is similar to high quality EuTe films with two narrow lines attributed to excitonic recombinations associated with magnetic polarons. For increasing x, the emission becomes dominated by a broader lower energy band, which is very efficient as compared to the binary emission. The magneto-optical properties of the ternary films show various similarities with EuTe results, such as quenchings at similar temperatures and magnetic fields. Most remarkably, they also present a giant effective g-factor that makes this material a strong candidate for spintronic applications.
Modulus mapping of nanoscale closure variants in Ni–Mn–Ga
Authors: Ganor Yaniv , Shilo Doron
Published: July 2008

The twinned magnetic microstructure of Ni2MnGa ferromagnetic shape-memory alloy is investigated by high resolution nanoscale modulus mapping. A surprisingly fine near-surface nanoscale substructure of closure magnetic twin variants was observed. The lateral distance between adjacent closure variants was found to be 100nm. The small size of twin variant prisms provides a unique opportunity for evaluating the twin boundary energy by considering the competition between the magnetic field and interface energies. Our estimate shows a relatively small twin boundary energy of 3ergs∕cm2, which suggests the ability of Ni2MnGa to form nanoscale structures of magnetic twin variants.
Improved GaN film overgrown with a molybdenum nanoisland mask
Authors: Lin Chaotong , Yu Guanghui , Wang Xinzhong , Cao Mingxia , Gong Hang , Qi Ming , Li Aizhen
Published: July 2008

We report the improved crystalline and optical quality of GaN film overgrown by hydride vapor phase epitaxy adopting a molybdenum (Mo) nanoisland mask (MNM). The MNM is fabricated following thermal annealing of the nanometer-thick Mo film deposited by electron-beam evaporation. The full width at half maximum values of high-resolution x-ray diffraction (HRXRD) rocking curves for the GaN film with MNM are 188arcsec (002 reflection) and 219arcsec (102 reflection), while those for the GaN film without MNM are 256 and 364arcsec, respectively. This result indicates a significant reduction of dislocation density in the overgrown GaN film with MNM. Photoluminescence spectra measurements reveal the compressive strain relaxation and improvement in the quality of the overgrown GaN film with MNM as compared to the regrown GaN film without MNM, which is consistent with the trend observed by HRXRD.
Incoherent structural relaxation of fivefold twinned nanowires
Authors: Fu Xin , Jiang Jun , Zhang Wenzheng , Yuan Jun
Published: July 2008

Boron carbide nanowires with a fivefold twinned structure have been shown to have regular spaced microtwin lamellas localized in one of the crystalline segments. This defect structure is interpreted as incoherent structural relaxation to relieve the angular excess. A structural model, in terms of a disclination core surrounded by a small angle grain boundary with an intersecting microtwin lamella pair structure, has been proposed and strain analyses suggest it could be a common phenomena for nanowires with large angular mismatch and small twinning formation energy.
The structure and local surrounding of Fe in Co2−xFe1+xSi
Authors: Jung Verena , Balke Benjamin , Fecher Gerhard H. , Felser Claudia
Published: July 2008

This work reports on the magnetostructural properties of Co2−xFe1+xSi with 0<x<1. The Heusler compound Co2FeSi is a half-metallic ferromagnet with high Curie temperature and was suggested as candidate for a high tunneling magnetoresistance. Changing the Fe content allows to tune its magnetic properties. It is demonstrated that the solid solution series Co2−xFe1+xSi is perfectly ordered. Fe57 Mössbauer spectroscopy was used to determine the local hyperfine magnetic fields of the Fe atoms. Two different hyperfine magnetic fields are detected in samples with x>0. Changes in the relative intensities indicate the well ordered substitution of Co by Fe atoms.
Alternative, Complementary, or Integrative Approaches to Treating Depression
Authors: Zahourek Rothlyn
Published: July 2008

More Americans are seeking out alternative, complementary, and integrative (ACI) approaches to painful chronic conditions, such as depression. This article reviews a variety of the interventions that are potentially helpfulfor those with depression. Approaches discussed include supplements, exercise, massage, light therapy, homeopathy, and rapid rate transcranial electromagnetic stimulation. Articles in the lay press abound and herbs, homeopathic remedies, and supplements are sold in supermarkets, drug stores, and catalogs. Persons use these approaches without consulting knowledgeable providers. Information related to the use of ACI approaches is often confusing, and many approaches are not supported by research. However, most ACI interventions enhance comfort and result in few dangerous side effects. Psychiatric nurses need to become knowledgeable about these interventions and can serve as a resource to clients by assessing the usefulness of ACI interventions and prescribing them in their practice.
The Power of Water: Developing Dialogues between Foucault and Gramsci
Authors: Ekers Michael , Loftus Alex
Published: July 2008

This paper develops an exchange between two important strands of research within contemporary human geography. One concerns the matter of socionatures; the other concerns the operation and establishment of power within liberal, capitalist social formations. Through mobilising some of the recent writings on the political ecology of water, we seek to show how an engagement with Gramscian and Foucauldian work on power could be mutually beneficial for both areas of research. In so doing, we seek to mobilise some of the tensions, as well as the points of engagement, between Gramscian and Foucauldian approaches. Through opening up the ways in which water contributes to the survival of liberal capitalist formations and also to the production of distinctive subjectivities, this dialogue provides new inroads into the politics and praxis of everyday life.
Gendered Occupational Differences and Earnings Gaps in Globalising Urban Economies: The Case of Tel-Aviv
Authors: Menahem Gila , Elias Nelly
Published: July 2008

The major theoretical purpose of the paper is to investigate the implications of globalising and restructuring urban economies on gender-related differences in occupational distribution and earnings within the urban context. The study uses data from national censuses (1983 and 1995) and a labour force survey of 2001, in Israel, to investigate the evolution of gender gaps in Tel-Aviv. The findings that point to the erosion of advantages in the globalising and restructuring urban economy, compared with the nation as a whole, may indicate new potential sources of gender inequality. The theoretical implications, for both the restructuring and globalisation theses and the study of sources of inequality among men and women, are discussed.
Revisiting the Price of Residential Land in Jakarta
Authors: Lewis Blane David
Published: July 2008

This paper corroborates the main stylised facts of previous studies regarding the relationship between urban residential land price and distance from the centre of the city: the effect of distance on land values is significant and negative and the influence of distance on the price of land has become less important over time. The analysis, using data from Jakarta, reveals that the use of market prices instead of appraised prices does not have much effect on the estimated land value gradient, although it does have major consequences for the estimated influence of environmental conditions on land price. Apparently, the market values environmental conditions to a significant degree whereas such conditions have no impact on government assessments of land price. The examination demonstrates that the elasticity of land price with respect to parcel size is significantly different from one, contrary to the assumption of the basic model, but that changing the naive model to reflect that fact does not have notable impact on the estimated land value gradient. Finally, the investigation illustrates the potential importance of using randomly generated data in the estimation of the influence of distance and other independent variables on land price. Utilisation of an incidental truncation model, which attempts to adjust for the non-random character of the sample data, results in an estimate of the absolute value of the land price gradient that is larger by a factor of two relative to that derived from the unadjusted model.
Müllerian Tumor (Atypical Polypoid Adenomyoma) with Sex-Cord Differentiation Arising from the Oviduct in an Adolescent Cynomolgus Monkey (Macaca fascicularis)
Authors: Satoh Hiroshi , Kai Kiyonori , Yabe Koichi , Fuj Fumitaka , Furuhama Kazuhisa
Published: July 2008

In a 6.5-year-old cynomolgus monkey ( Macaca fascicularis), a tumor mass was macroscopically located near the right ovary, connected to the oviduct, and completely separated from the uterus. The mass was an elongated spherical shape with a smooth surface and milky-white color. It was approximately 3.5 cm across its major axis, and the sagittal section was composed of cystic walls and a multi-lobular luminal nodule. Light-microscopically, the polypoid mass consisted of admixtures of neoplastic mesenchymal and epithelial elements. Lipid-rich foamy cells scattered within the tumor mass formed nest-like/aggregated populations. Immunohistochemically, mesenchymal tumor cells stained diffusely positive for vimentin, desmin, and alpha ( α)-smooth muscle actin, demonstrating a smooth muscle origin. Mesenchymal tumor cells contained mitotic figures, and tumor elements including mesenchymal, epithelial, and lipid-rich foamy cells stained strongly positive for proliferating cell nuclear antigen (PCNA). Moreover, lipid-rich foamy cells elicited positive reactions for testosterone, suggesting sex-cord element differentiation. Electron-microscopically, actin filaments, basement membranes, and electron-dense cytoplasmic bodies were noted in the spindle cells, and invaginated nuclei were observed in adenomatous cells. In contrast, foamy cells contained numerous lipid vacuoles in the cytoplasm. From these findings, the tumor was diagnosed as an atypical polypoid adenomyoma (benign mixed müllerian tumor) with sex-cord differentiation arising from the oviduct. This tumor was considered to be an exceedingly rare finding in the adolescent cynomolgus monkey.
The Incidence of Thymic B Lymphoid Follicles in Healthy Beagle Dogs
Authors: Ploemen Jan-Peter H. T. M. , Ravesloot Wilma T.M. , Van Esch Eric
Published: July 2008

The incidence of thymic B cell lymphoid follicles was retrospectively studied in 62 male and 58 female healthy control beagle dogs (age 11.3 ± 4.8, range 6 to 23 months). The animals were selected from toxicological studies performed in the period 1990—2001 at the Organon labs. The animals had received vehicle treatment. Thorough microscopic examination of the thymus in hematoxylin & eosin (H&E)-stained sections resulted in an unexpectedly high overall incidence of 70% of medullary lymphoid follicles. Occasionally, these lymphoid follicles contained germinal centers. With the use of a T- and B cell marker (respectively CD3 and CD79 α) we confirmed that the lymphoid follicles exclusively contained large numbers of B lymphocytes. Moreover, with the use of the B cell marker, almost all animals (97%) prove to have B cell rich medullary areas. The study also confirmed that the dog thymus underwent progressive involution during the period from 6 to 23 months of age. As a consequence of the involution, B cell areas and lymphoid follicles may be obscured in some H&E sections. Results of this study indicated that dense B lymphocyte aggregates and/or B lymphoid follicles are a normal constituent of the canine thymus.
Induction of Transitional Cell Hyperplasia in the Urinary Bladder and Aberrant Crypt Foci in the Colon of Rats Treated with Individual and a Mixture of Drinking Water Disinfection By-Products
Authors: Mcdorman Kevin S. , Chandra Sundeep , Hooth Michelle J. , Hester Susan D. , Schoonhoven Robert , Wolf Douglas C.
Published: July 2008

Cancer of the urinary bladder and colon are significant human health concerns. Epidemiological studies have suggested a correlation between these cancers and the chronic consumption of chlorinated surface water containing disinfection by-products (DBPs). The present study was designed to determine if exposure to DBPs would cause preneoplastic or neoplastic lesions in the urinary bladder and colon of rats, and what effect a mixture of DBPs would have on these lesions. Male and female Eker rats were treated via drinking water with low and high concentrations of potassium bromate, 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5 H)-furanone (MX), chloroform, or bromodichloromethane individually or in a mixture for 10 months. The urinary bladders and colons were examined for the presence of preneoplastic lesions. Cell proliferation in the urothelium was examined using immunohistochemical staining for bromodeoxyuridine. Aberrant crypt foci (ACF), as well as the number of individual crypts in each ACF, were identified and counted microscopically after staining with 0.2% methylene blue. Colon crypt cell proliferation and mitotic index were determined using immunohistochemical staining for proliferating cell nuclear antigen. Labeling indexes for the urinary bladder and colon were calculated based on the percentage of positively labeled cells. Treatment with the high dose of MX caused transitional epithelial hyperplasia and cell proliferation in the rat urinary bladder, and this effect was diminished in the high dose mixture animals. Treatment with 4 individual DBPs, as well as a mixture of them, caused the development of ACF, the putative preneoplastic lesion of colon cancer.
Hylan G-F 20 Induces Delayed Foreign Body Inflammation in Guinea Pigs and Rabbits
Authors: Sasaki Masanori , Miyazaki Yuka , Takahashi Toyomi
Published: July 2008

Recent clinical evidence suggests that hylan, a modified hyaluronan, and related products potentially elicit foreign body granulomatous inflammation in human soft tissue. We investigated the biocompatibility of hylan G-F 20 (Synvisc) for up to 28 days after intradermal injection in guinea pigs and intramuscular injection in rabbits. Compared to saline and unmodified hyaluronan, hylan induced definitive macroscopic changes in guinea pigs by day 14 or later and in rabbits by 28 days after injection. Histologically, at the injection sites, there was severe granulomatous inflammation in guinea pigs and acute inflammation with minimal infiltration of macrophages and foreign body giant cells in rabbits. Furthermore, specific antibodies against hylan were demonstrated in guinea pigs by passive cutaneous anaphylaxis, and substantial deposits of IgG on hylan were evident by immunohistochemistry. The present results contradict previous reports on biocompatibility of hylan and suggest that hylan may potentially induce similar unfavorable reactions in humans.
Immune Responses in the Lung and Local Lymph Node of A/J Mice to Intranasal Sensitization and Challenge with Adjuvant-Free Ovalbumin
Authors: Farraj Aimen K. , Harkema Jack R. , Jan Tong-Rong , Kaminski Norbert E.
Published: July 2008

Pathologic features of IgE-mediated allergic airway diseases include airway infiltration of inflammatory cells (eg, lymphocytes, plasma cells, and eosinophils) and mucous cell metaplasia (MCM) in airway epithelium. CD4+ T lymphocytes, specifically those producing a type 2 (Th2) cytokine profile, are necessary for the induction of IgE-mediated allergic airway responses. Most experimental models of IgE-mediated allergic airway disease use systemic (eg, intraperitoneal) administration of an allergen coupled with an adjuvant to sensitize animals. Cytokine changes are measured in a number of ways including in bronchoalveolar lavage fluid (BALF) or lymph node cells stimulated ex vivo. The primary objective of this study was to test the hypothesis that intranasal sensitization and challenge of mice with ovalbumin in the absence of an adjuvant will induce the pathologic features that are characteristic of IgE-mediated allergic airway disease. Another objective was to determine if intranasal delivery of this allergen will result in the induction of a profile of cytokine gene expression in the lung and tracheobronchial (TB) lymph node, that is typical of immunologic changes associated with IgE-mediated allergic airway disease. Only mice that were intranasally sensitized and challenged with ovalbumin exhibited pulmonary lesions that included marked MCM in the respiratory epithelium lining the nasal and pulmonary airways, and an associated mixed inflammatory cell influx consisting of lymphocytes, plasma cells and eosinophils. Ovalbumin-treated mice also exhibited enhanced expression of the Th2 cytokine mRNAs IL-4, IL-5, IL-10, and IL-13 in the lung and IL-4 in the TB lymph node, and concurrent increases in ovalbumin-specific IgE in the serum. The results of this study indicate that A/J mice intranasally instilled with ovalbumin without adjuvant have the hallmark histopathologic and immunologic features of IgE-mediated allergic airway disease of humans.
A Fast Histochemical Staining Method to Identify Hyaline Droplets in the Rat Kidney
Authors: De Rijk Eveline P.C.T. , Ravesloot Wilma T.M. , Wijnands Yvonne , Van Esch Eric
Published: July 2008

Hyaline droplet formation in the proximal tubular cells of the kidney commonly occurs under different pathological conditions in experimental animals. In rats, intracytoplasmic hyaline droplet formation is predominantly associated with accumulation of the male rat-specific α2u-globulin, whereas under other (pathological) conditions (eg, histiocytic sarcoma and chronic progressive nephropathy [CPN]) other proteins are involved. Staining methods to visualize hyaline droplets either need plastic embedded material or time-consuming (immuno)histochemical methods. A fast Chromotrope-Aniline-Blue-staining on formalin-fixed paraffin-embedded kidneys taking only 30 minutes is described. Using this method, hyaline droplets consisting of different types of proteins are easily recognized by their bright-red color.
Developmental Toxicology Studies of WHI-07, a Novel Nucleoside Analogue-Based Dual-Function Microbicide, Administered Intravaginally to Rabbits
Authors: D'Cruz Osmond J. , Erbeck Douglas , Uckun Fatih M.
Published: July 2008

The zidovudine derivative, 5-bromo-6-methoxy-5,6-dihydro-3-azidothymidine-5'-( p-bromophenyl) methoxy alaninyl phosphate (WHI-07), is a dual-function spermicidal and anti-HIV agent with contraceptive and microbicidal activity. In previous subchronic and reproductive toxicity studies and a two-year carcinogenicity study, daily intravaginal application of 0.5 to 2.0% WHI-07 via a gel-microemulsion, was shown to cause no local, systemic and reproductive toxicity or increased carcinogenicity in mice. To evaluate the developmental toxicity potential of WHI-07 in a nonrodent model, subgroups of 20 superovulated NZW rabbits were artificially inseminated and exposed intravaginally to a gel-microemulsion containing 0, 0.5, 1.0, or 2.0% WHI-07 during major organogenesis [gestation days 6—18]. The dose of WHI-07 was equivalent to 1 .4 × 106 to 5 .7 × 106 times its anti-HIV IC50 and 1400 to 5700 times its spermicidal EC50. Throughout the duration of the experiment (GD 0-29), clinical observations, food consumption, and body weights were recorded. Reproductive and fetal parameters were evaluated following uterotomies on GD 29. Measurements included numbers of corpora lutea, pregnancy, number and distribution of implantations, resorptions, live and dead fetuses, fetal weight, sex ratio, and gross external and skeletal malformations and variations. Maternal food consumption and body weight gain were unaffected by WHI-07 treatment. Hematologic and clinical chemistry determinations on GD 19 and 29 revealed no treatment-related maternal effects. Prior studies of repeated intravaginal administration of WHI-07 gel-microemulsion revealed lack of local toxicity to rabbit vaginal mucosa. In the current study, no drug-related gross lesions were apparent at necropsy. Reproductive indices, ie, pregnancy rate, gravid uterine weights, litter size, number of corpora lutea, implantation sites, pre- and postimplantation losses, viable fetuses, resorptions, fetal body weights, and fetal sex ratio, were not affected by intravaginal exposure to WHI-07. External, and skeletal examinations of fetuses for malformations and variations did not reveal any evidence of teratogenicity in any WHI-07-treated groups. Intravaginal administration of WHI-07 at concentrations as high as 2% did not produce teratogenicity or other developmental toxicity in rabbit conceptus. These findings indicated that WHI-07 shows unique clinical potential to become the active ingredient of a new female-controlled topical microbicidal vaginal contraceptive for women who are at high risk of acquiring HIV/AIDS.
Invited Reviews: Carcinogenic and Systemic Health Effects Associated with Arsenic Exposure—A Critical Review
Authors: Tchounwou Paul B. , Patlolla Anita K. , Centeno Jose A.
Published: July 2008

Arsenic and arsenic containing compounds are human carcinogens. Exposure to arsenic occurs occupationally in several industries, including mining, pesticide, pharmaceutical, glass and microelectronics, as well as environmentally from both industrial and natural sources. Inhalation is the principal route of arsenic exposure in occupational settings, while ingestion of contaminated drinking water is the predominant source of significant environmental exposure globally. Drinking water contamination by arsenic remains a major public health problem. Acute and chronic arsenic exposure via drinking water has been reported in many countries of the world, where a large proportion of drinking water is contaminated with high concentrations of arsenic. General health effects that are associated with arsenic exposure include cardiovascular and peripheral vascular disease, developmental anomalies, neurologic and neurobehavioural disorders, diabetes, hearing loss, portal fibrosis, hematologic disorders (anemia, leukopenia and eosinophilia) and multiple cancers: significantly higher standardized mortality rates and cumulative mortality rates for cancers of the skin, lung, liver, urinary bladder, kidney, and colon in many areas of arsenic pollution. Although several epidemiological studies have documented the sources of exposure and the global impact of arsenic contamination, the mechanisms by which arsenic induces health effects, including cancer, are not well characterized. Further research is needed to provide a better understanding of the pathobiology of arsenic-induced diseases and to better define the toxicologic pathology of arsenic in various organ systems. In this review, we provide and discuss the underlying pathology and nature of arsenic-induced lesions. Such information is critical for understanding the magnitude of health effects associated with arsenic exposure throughout the world.
Effects of Granulocyte Colony-Stimulating Factor (G-CSF) on Bleomycin-Induced Lung Injury of Varying Severity
Authors: Adachi Kenji , Suzuki Masami , Sugimoto Tetsurou , Yorozu Keigo , Takai Hirotake , Uetsuka Koji , Nakayama Hiroyuki , Doi Kunio
Published: July 2008

We evaluated the effects of granulocyte colony-stimulating factor (G-CSF) on bleomycin (BLM)-induced lung injury that developed diffuse alveolar damage and subsequent pulmonary fibrosis (PF) of varying severity. G-CSF (100 μg/kg/day) was administered subcutaneously to BLM (0.2, 20, 2,000 μg)-treated or -untreated rats for 3 or 14 days. In the BLM 0.2 μg group, slight alveolar mononuclear cell infiltration was observed, although PF was not noted. In the BLM 20- μg and 2,000- μg groups, diffuse alveolar damage along with neutrophil infiltration and subsequent PF were observed. In the saline + G-CSF group and BLM 0.2 μg + G-CSF group, a marked increase in the number of alkaline phosphatase (ALP)-positive neutrophils was noted in the alveolar capillaries, although there was neither neutrophil infiltration in alveoli nor exacerbation of lung injury. In the BLM 20 μg + G-CSF and BLM 2,000 μg + G-CSF groups, an exacerbation of lung injury along with an increase in the number of ALP-positive neutrophils in the alveoli was observed. These results indicate that the administration of G-CSF to rats with slight lung injury bearing no PF does not exacerbate the lung injury. The exacerbating effects of G-CSF seem to be associated not only with the marked infiltration of activated neutrophils but also with the severity of underlying lung injury.
Slug is a direct Notch target required for initiation of cardiac cushion cellularization
Authors: Niessen Kyle , Fu YangXin , Chang Linda , Hoodless Pamela A. , McFadden Deborah , Karsan Aly
Published: July 2008

Snail family proteins are key regulators of epithelial-mesenchymal transition, but their role in endothelial-to-mesenchymal transition (EMT) is less well studied. We show that Slug, a Snail family member, is expressed by a subset of endothelial cells as well as mesenchymal cells of the atrioventricular canal and outflow tract during cardiac cushion morphogenesis. Slug deficiency results in impaired cellularization of the cardiac cushion at embryonic day (E)–9.5 but is compensated by increased Snail expression at E10.5, which restores cardiac cushion EMT. We further demonstrate that Slug, but not Snail, is directly up-regulated by Notch in endothelial cells and that Slug expression is required for Notch-mediated repression of the vascular endothelial cadherin promoter and for promoting migration of transformed endothelial cells. In contrast, transforming growth factor β (TGF-β) induces Snail but not Slug. Interestingly, activation of Notch in the context of TGF-β stimulation results in synergistic up-regulation of Snail in endothelial cells. Collectively, our data suggest that combined expression of Slug and Snail is required for EMT in cardiac cushion morphogenesis.
An Analytical Study of a Composite Dovetail Joint
Authors: Semb Gunnar , Gradin Per A , Hällgren Ingvar
Published: July 2008

In this paper a simple analytical model for determining the elastic fields in a so called dovetail joint is developed. The model is restricted to joints having a small wedge angle. With some simplifying assumptions regarding for example the mechanical behaviour of the wedge material, the elastic fields can be expressed in terms of convergent polynomial series. Two situations in which closed form solutions exists are identified: (a)when the lateral contraction of the laminates can be ignored, the laminate displacement is obtained in closed form in terms of Bessel functions, whereas (b): when the wedge can be considered to be rigid, it is obtained in terms of exponential functions. Finally, some numerical examples regarding contact pressure, stress distribution and stiffness are presented.
Property Modeling Across Transition Temperatures in Polymers: Application to Filled and Unfilled Polybutadiene
Authors: Mahieux C. A. , Reifsnider K. L.
Published: July 2008

A new model was recently established describing the stiffness of polymers as a function of temperature. This polymer stiffness-temperature model was proven to be applicable to thermoplastics for the entire temperature range from the glassy state to the flow of the material. The present paper focuses on the potential application of the statistical stiffness-temperature model to an elastomer system. A new set of cryogenic DMA data for filled and unfilled Polybutadiene was established. The effects of molecular weight and carbon black content on the mechanical response of the elastomer were carefully studied. The polymer stiffness-temperature model was applied to the polybutadiene system and the effect of the various microstructures on the model inputs was investigated. Finally, conclusions were drawn on the applicability of the stiffness-temperature model to elastomer systems.
Studies on the Rheology and the Mechanical Properties of Thermoplastic Elastomer from Latex Product Waste and High Density Polyethylene
Authors: Rajalekshmi S. , Joseph Rani
Published: July 2008

Latex waste products contain rubber hydrocarbon of very high quality, which is only lightly cross linked. Selected wastes such as thread waste and glove waste were modified into processable materials by a novel economic process and thermoplastic elastomers were prepared by blending these modified waste materials with high density polyethylene in various proportions. The mechanical properties as well as the rheological behaviour of these blends were evaluated and compared with those of the natural rubber-high density polyethylene blends.