bluuebunny/crossref_metadata_2025 huggingface dataset:
Inhibition of Nuclear Factor-κB or Bax Prevents Endoplasmic Reticulum Stress- But Not Nitric Oxide-Mediated Apoptosis in INS-1E Cells
Authors: Tonnesen Morten F. , Grunnet Lars G. , Friberg Josefine , Cardozo Alessandra K. , Billestrup Nils , Eizirik Décio L. , Størling Joachim , Mandrup-Poulsen Thomas
Published: June 2009

Accumulating evidence suggests that endoplasmic reticulum (ER) stress by mechanisms that include ER Ca2+ depletion via NO-dependent down-regulation of sarcoendoplasmic reticulum Ca2+ ATPase 2b (SERCA2b) contributes to β-cell death in type 1 diabetes. To clarify whether the molecular pathways elicited by NO and ER Ca2+ depletion differ, we here compare the direct effects of NO, in the form of the NO donor S-nitroso-N-acetyl-d,l-penicillamine (SNAP), with the effects of SERCA2 inhibitor thapsigargin (TG) on MAPK, nuclear factor κB (NFκB), Bcl-2 proteins, ER stress, and apoptosis. Exposure of INS-1E cells to TG or SNAP caused caspase-3 cleavage and apoptosis. Both TG and SNAP induced activation of the proapoptotic transcription factor CCAAT/enhancer-binding protein homologous protein (CHOP). However, other classical ER stress-induced markers such as up-regulation of ER chaperone Bip and alternative splicing of the transcription factor Xbp-1 were exclusively activated by TG. TG exposure caused NFκB activation, as assessed by IκB degradation and NFκB DNA binding. Inhibition of NFκB or the Bcl-2 family member Bax pathways protected β-cells against TG- but not SNAP-induced β-cell death. These data suggest that NO generation and direct SERCA2 inhibition cause two quantitative and qualitative different forms of ER stress. In contrast to NO, direct ER stress induced by SERCA inhibition causes activation of ER stress signaling pathways and elicit proapoptotic signaling via NFκB and Bax.
Activation of Liver X Receptor Regulates Substrate Oxidation in White Adipocytes
Authors: Stenson Britta M. , Rydén Mikael , Steffensen Knut R. , Wåhlén Kerstin , Pettersson Amanda T. , Jocken Johan W. , Arner Peter , Laurencikiene Jurga
Published: June 2009

Liver X receptors (LXRs) are nuclear receptors with established roles in cholesterol, lipid, and carbohydrate metabolism, although their function in adipocytes is not well characterized. Increased adipose tissue mass in obesity is associated with increased adipocyte lipolysis. Fatty acids (FA) generated by lipolysis can be oxidized by mitochondrial β-oxidation, reesterified, or released from the adipocyte. The latter results in higher circulating levels of free FAs, in turn causing obesity-related metabolic complications. However, mitochondrial β-oxidation can at least in part counteract an increased output of FA into circulation. In this study, we provide evidence that activation of LXRs up-regulates mitochondrial β-oxidation in both human and murine white adipocytes. We also show that the expression of a kinase regulating the cellular fuel switch, pyruvate dehydrogenase kinase 4 (PDK4), is up-regulated by the LXR agonist GW3965 in both in vitro differentiated human primary adipocytes and differentiated murine 3T3-L1 cells. Moreover, activation of LXR causes PDK4-dependent phosphorylation of the pyruvate dehydrogenase complex, thereby decreasing its activity and attenuating glucose oxidation. The specificity of the GW3965 effect on oxidation was confirmed by RNA interference targeting LXRs. We propose that LXR has an important role in the regulation of substrate oxidation and the switch between lipids and carbohydrates as cellular fuel in both human and murine white adipocytes.
Cleaner gobies evolve advertising stripes of higher contrast
Authors: Lettieri L. , Cheney K. L. , Mazel C. H. , Boothe D. , Marshall N. J. , Streelman J. T.
Published: June 2009

Elacatinus gobies of the Caribbean have undergone rapid speciation along ecological axes, and particular species from this genus act as`cleaners' that remove ectoparasites from larger coral reef fish, termed`clients'. Evolutionary shifts in habitat use, behavior and lateral body stripe colors differentiate cleaners from ancestral sponge-dwelling lineages. High-contrast stripe colors associated with cleaning behavior on coral reefs may have evolved as a signal of cleaning status. We asked whether cleaner gobies with blue stripes are more conspicuous than ancestral yellow- and green-stripe phenotypes to a diverse set of potential client visual systems in the tropical reef environment where cleaning stations are commonly observed. Using spectrophotometric measurements of cleaners with blue and yellow stripes and their F1 hybrid, we tested the contrast of each color stripe to both potential dichromatic and trichromatic reef fish visual systems, against typical coral and sponge microhabitat background colors. Blue stripes provide the highest average chromatic contrast across a range of possible microhabitat colors to the majority of fish visual systems tested. The contrast provided by yellow and hybrid green stripes are comparable across habitats to dichromatic visual systems. The green stripe is less contrasting than both blue and yellow to many potential trichromatic visual systems. We suggest that the evolution of blue stripes in Elacatinus gobies could be a result of natural selection for signals of high color contrast, driven by the sensory biases and visual systems of diverse reef fish clients.
Mudskipper pectoral fin kinematics in aquatic and terrestrial environments
Authors: Pace C. M. , Gibb A. C.
Published: June 2009

Mudskippers use pectoral fins for their primary mode of locomotion on land and pectoral fins in conjunction with the axial musculature and caudal fin to move in water. We hypothesized that distinct pectoral fin movements enable effective locomotion in each environment. Additionally, we made three functional predictions about fin movements during locomotion on land versus water: the pectoral fin is depressed more on land than in water; the pectoral fin will have greater changes in fin area between propulsive and recovery phases in water versus land; anterior and posterior excursions will be greater on land than in water. Locomotion was recorded in each environment using a high-speed digital-imaging system and kinematic variables were calculated from digitized landmark points. Variables were analyzed using principal components analysis and matched pairs t-tests. Mudskippers produce distinct kinematic patterns across environments (P<0.003), although only some of our predictions were supported. The magnitude of fin depression is the same across habitats. However, depression occurs during the propulsive phase on land (by –0.60 cm), whereas during the propulsive phase in water the fin is elevated (by+0.13 cm). We were unable to support the hypothesis that fin orientation differs between environments. Lastly, anterior extension of the fin is greater on land (1.8 cm, versus 1.3 cm in water), creating a larger stride length in this environment. We posit that the mudskipper pectoral fin may facilitate stability in water and thrust production on land, and suggest that the robust fin morphology of the goby lineage may predispose species within this group to terrestrial locomotion.
`Different strokes for different folks': geographically isolated strains ofLymnaea stagnalisonly respond to sympatric predators and have different memory forming capabilities
Authors: Orr Michael V. , Hittel Karla , Lukowiak Ken
Published: June 2009

Gaining insight into how natural trait variation is manifest in populations shaped by differential environmental factors is crucial to understanding the evolution, ecology and sensory biology of natural populations. We have demonstrated that lab-reared Lymnaea detect and respond to the scent of a crayfish predator with specific, appropriate anti-predator behavioral responses, including enhanced long-term memory (LTM) formation, and that such predator detection significantly alters the electrophysiological activity of RPeD1, a neuron that is a necessary site for LTM formation. Here we ask: (1)do distinct populations of wild Lymnaea stagnalis respond only to sympatric predators and if so, can these traits be quantified at both the behavioral and neurophysiological levels, and (2) does the presence of a non-sympatric predator elicit anti-predator behaviors including augmentation of LTM? We tested three different populations of wild (i.e. not lab-reared)snails freshly collected from their natural habitat: (1) polders near Utrecht in The Netherlands, (2) six seasonally isolated ponds in the Belly River drainage in southern Alberta, Canada and (3) a 20-year-old human-made dugout pond in southern Alberta. We found strain-specific variations in the ability to form LTM and that only a sympatric predator evoked anti-predatory behaviors, including enhanced LTM formation and changes in RPeD1 activity.
Constraint effect in deformation of copper interconnect lines subjected to cyclic Joule heating
Authors: Read D T , Geiss R H , Barbosa N
Published: June 2009

Temperature distributions and von Mises strains produced by cyclic Joule heating of damascene copper interconnect structures of varying geometries were calculated by finite element analysis. Constraining the top surface of the lines with rigid dielectric increased the temperature range required to produce a given strain range, relative to unconstrained lines. Much narrower lines required much higher temperatures to reach this same range of strain. Electrical tests to failure of actual structures were conducted. Scanning electron microscope images of unconstrained damascene copper lines after testing showed significant topographic features that have been associated in previous reports with mechanical fatigue. None of the constrained lines – including those cycled at ranges of total strain similar to those of the unconstrained lines – exhibited these features, but they did have large voids. Present and previously reported observations suggest that both cyclic plastic deformation and void formation can contribute to damage and failure of small-scale structures subjected to cyclic Joule heating, and that mechanical constraint has a strong effect on the operation of these mechanisms.
Strain sensing using a multiwalled carbon nanotube film
Authors: Vemuru S M , Wahi R , Nagarajaiah S , Ajayan P M
Published: June 2009

The effectiveness of multiwalled carbon nanotubes (MWCNTs) as strain sensors is investigated. The key contribution of this paper is the study of real-time strain response at the macroscale of MWCNT film under tensile load. In addition, real-time voltage change as a function of temperature is examined. MWCNT films attached to a brass specimen by epoxy using vacuum bonding have been studied. The brass specimen is subjected to tensile loading, and voltage output from the MWCNT film is obtained using a four-point probe and a sensitive voltage measurement device. Experimental results show that there is a linear change in voltage across the film when subjected to tension, and the MWCNT film both fully recovers its unstressed state upon unloading and exhibits stable electromechanical properties. The effect of temperature on the voltage output of the nanotube film under no load condition is investigated. From the results obtained it is evident that MWCNT films exhibit a stable and predictable voltage response as a function of temperature. An increase in temperature leads to an increase in conductivity of the nanotube film. The study of MWCNT film for real-time strain sensing at the macroscale is very promising, and the effect of temperature on MWCNT film (with no load) can be reliably predicted.
Stress concentrations around a pressurized hole close to a uniformly loaded boundary
Authors: Scirè Mammano G , Dragoni E
Published: June 2009

The elastic stresses arising around a pressurized circular hole close to a free or uniformly loaded boundary are examined. The boundary near to the hole can represent the periphery of a circular disc, the straight edge of a half-plane, or the contour of a second circular hole. All three configurations are modelled with the same general geometry, described by means of bipolar coordinates, from which each particular shape is obtained by assigning a suitable value to the curvature of the adjacent boundary. An exact solution found in the literature, covering the cases of a pressurized hole cut in a disc or in a half-plane, is developed semi-analytically to solve the third case of two arbitrary, loaded, adjacent holes. For the three cases examined, closed-form expressions are derived for the stress distributions along the contour of the hole and along the nearby edge. These expressions hold true for any geometry and for arbitrary combinations of uniform loadings on the two boundaries. For the special case of a pressurized hole close to a free edge, readily accessible charts of stress concentration factors are also provided.
Modelling of laser processing cut quality by an adaptive network-based fuzzy inference system
Authors: Subramonian Sivarao , Brevern P , El-Tayeb N S M , Vengkatesh V C
Published: June 2009

Real-world problems in precision machining now require intelligent systems that integrate knowledge, techniques, and methodologies. Intelligent systems possess human-like expertise within a specific domain to adapt themselves and to learn to do better in making decisions for an intelligent manufacturing system. An intelligent tool called adaptive network-based fuzzy inference system (ANFIS) was used to model and predict the laser cut quality of a 2.5 mm manganese—molybdenum (Mn—Mo) alloy pressure vessel plate in this article. A 3 kW CO2 laser machine with seven selected design parameters was used to carry out 128 experiments based on 2 k factorial design with single replication. Because surface roughness (Ra) was the response parameter, it was targeted to be <15 μm to meet the requirement and benchmark of the pressure vessel manufacturer who sponsored this project. The DIN 2310-5 German laser cutting of metallic materials standard and procedure was referred to for evaluating surface roughness, where experimentally obtained results were used for Ra predictive modelling. Predictions of non-linear laser processing by ANFIS were found to be extremely promising in supplying the desired output, where Ra was predicted to an excellent degree of accuracy, reaching almost 70 per cent with the experimental pure error below 30 per cent.
Application of a two-dimensional lifting wavelet transform to rotating mechanical vibration data compression
Authors: Bao W , Wang W , Zhou R , Li N , Yang J , Yu D
Published: June 2009

This article presents a novel method for rotating mechanical vibration data compression based on a two-dimensional (2D) lifting wavelet transform. This method consists of three stages. First, the periodical vibration data are converted from one-dimensional (1D) to 2D in order to reduce the dependency both within a single cycle and across cycles more efficiently. Then, the 2D matrix is decomposed based on a 2D wavelet transform via biorthogonal filters constructed by the lifting scheme. Second, with the purpose of data compression, the significant wavelet coefficients are selected to retain while the small coefficients are discarded owing for their lesser contribution to the reconstruction signal. Finally, the reserved coefficients are utilized to reconstruct the 2D matrix through inverse wavelet transform and the reconstructed vibration data can be obtained by transforming the matrix from 2D to 1D. To evaluate the performance of the proposed compression method, the real-life rotating mechanical vibration data were used to test this method. The results show that the proposed method can achieve better performance compared to the method based on a 1D wavelet transform.
System reliability modelling: The current capability and potential future developments
Authors: Andrews J
Published: June 2009

This article describes the state-of-the-art methods available for systems reliability assessment. The significant contributions made to those methods in common use for the analysis of industrial systems are identified. The article reviews the developments in engineering systems that are likely to occur over the next decade that will challenge the current capability in this field and the potential advances that may result. A discussion is also provided of novel uses that will become possible due to the advances made in the assessment techniques over this period.
The thermal expansion behaviour of polyamide composites filled with surface modified carbon fibre
Authors: Jian L , Xiaohua Y
Published: June 2009

A comparison was made of the effects of coupling regents (RES) surface modification and air oxidation on the improvement of the interfacial adhesion of carbon fibres in reinforced polyamide (PA) composites. Results showed that RES modification greatly strengthens the adhesion between the reinforcement and matrix and is superior to improvements produced by surface oxidation in air. The optimum interfacial adhesion was reached at 0.3 wt% RES concentration. The thermal expansion behaviours of the carbon fibre reinforced PA (CF—PA) composite also showed that RES modification improved the interfacial adhesion.
The addition of polyamide-6 on tensile properties of carbon fibre reinforced acrylonitrile-butadiene-styrene composites
Authors: Li J , Zhang Y F
Published: June 2009

Acrylonitrile-butadiene-styrene (ABS) terpolymer was reinforced with HNO3-treated short carbon fibres (HCFs). The effects of HCF concentration on the tensile properties of the composites were examined. Increasing the HCF concentration in the ABS matrix from 10wt% to 30wt% resulted in improved tensile strength and tensile modulus. To obtain a strong interaction at the interface, polyamide-6 (PA6) at varying concentrations was introduced into the ABS/10wt% short carbon fibre (SCF) composite. The incorporation and increasing amount of PA6 in the composites increased tensile properties of the ABS/PA6/HCF systems because of improved adhesion at the interface, which was confirmed by the ratio of tensile strength as an adhesion parameter. These results were also supported by scanning electron micrographs of the ABS/PA6/HCF composites, which exhibited an improved adhesion between the SCFs and the ABS/PA6 matrix.
On the limitations of two- and three-dimensional linear hydroelasticity analyses applied to a fast patrol boat
Authors: Santos F M , Temarel P , Soares C Guedes
Published: June 2009

The aim of this paper is to study the symmetric (i.e. heave and pitch motions and distortions associated with vertical bending) wave-induced dynamic behaviour of a fast patrol boat using a unified hydroelasticity analysis. This includes two- and three-dimensional structural idealizations using beam and three-dimensional finite element modelling. The fluid—flexible structure interaction is carried out using three-dimensional potential flow analysis, for both structural idealizations, based on a pulsating source singularity distribution on the mean wetted surface. The calculations are carried out in regular waves for two forward speeds (Froude numbers Fn = 0.5 and 0.63) and three heading angles, i.e. 180 (head), 135, and 90 degrees. Results from full-scale trials are also presented in order to compare rigid body motion transfer functions with numerical predictions. There are large differences between numerically predicted and measured motions, as is to be expected for this fast hull form. The paper reports that the evaluation of the dynamic behaviour of the fast patrol boat, with small length to beam ratio, by means of the unified hydroelastic analysis, shows some inherent limitations of the beamlike approach for this particular type of vessel.
Polypyrrole/oligonucleotide nanocomposite: Its initial growth
Authors: Li Y , Jiang J H , Ma X D , Dong G X , Wang J , Paul Sung K-L
Published: June 2009

In this work, the initial growth process of a polypyrrole/oligonucleotide (PPy/ODN) nanocomposite electrochemically synthesized on an indium tin oxide (ITO)-coated glass surface was investigated by means of chronoamperometric measurements combined with optical microscopy and atomic force microscopy (AFM). It was found that the growth of PPy/ODN onto ITO was a three-stage process including incubation, rapid nucleation and growth, and constant nucleation and growth. The presence of ODN molecules significantly shortened the first stage. Further analysis showed that the nucleation and growth mechanism of PPy/ODN was progressive nucleation and 3D growth, which then changed to instantaneous nucleation and 3D growth before nucleus overlapping. In the third stage, the nucleation and growth mechanism of PPy/ODN was a combination of progressive nucleation and 3D growth and instantaneous nucleation and 3D growth.
A Decision-Analytic Approach to Reliability-Based Design Optimization
Authors: Bordley Robert F. , Pollock Stephen M.
Published: June 2009

Reliability-based design optimization is concerned with designing a product to optimize an objective function, given uncertainties about whether various design constraints will be satisfied. However, the widespread practice of formulating such problems as chance-constrained programs can lead to misleading solutions. While a decision-analytic approach would avoid this undesirable result, many engineers find it difficult to determine the utility functions required for a traditional decision analysis. This paper presents an alternative decision-analytic formulation that, although implicitly using utility functions, is more closely related to probability maximization formulations with which engineers are comfortable and skilled. This result combines the rigor of decision analysis with the convenience of existing optimization approaches.
Constructing Risk Measures from Uncertainty Sets
Authors: Natarajan Karthik , Pachamanova Dessislava , Sim Melvyn
Published: June 2009

We illustrate the correspondence between uncertainty sets in robust optimization and some popular risk measures in finance and show how robust optimization can be used to generalize the concepts of these risk measures. We also show that by using properly defined uncertainty sets in robust optimization models, one can construct coherent risk measures and address the issue of the computational tractability of the resulting formulations. Our results have implications for efficient portfolio optimization under different measures of risk.
Changes in student teachers' agency beliefs during a teacher education year, and relationships with observed classroom quality, and day‐to‐day experiences
Authors: Malmberg Lars‐Erik , Hagger Hazel
Published: June 2009

Background Conceptualizations of teachers' agency beliefs converge around domains of support and instruction.

Aim We investigated changes in student teachers' agency beliefs during a 1 year teacher education course, and related these to observed classroom quality and day‐to‐day experiences in partnership schools during the practicum.

Samples Out of a sample of 66 student teachers who had responded to at least two out of four times to a questionnaire (18 men 48 women; mean age 26.4 years), 30 were observed during teaching, and 20 completed a 4‐day short form diary.

Methods Confirmatory factor analysis validated two agency belief constructs. Multi‐level models for change investigated individual differences in change over time. Multi‐level path models related observation and diary responses to agency beliefs.

Results Supportive agency belief was high and stable across time. Instructional agency belief increased over time, suggesting a beneficial effect of teacher education. This increase was predicted by observed classroom quality (emotional support and student engagement) and daily positive affect and agency beliefs.

Conclusions Teacher education is successful in creating a context in which student teachers' supportive agency beliefs can be maintained and instructional agency beliefs can increase during the course.
The relationship between dispositional mindfulness and conditional goal setting in depressed patients
Authors: Crane Catherine , Barnhofer Thorsten , Hargus Emily , Amarasinghe Myanthi , Winder Rosie
Published: June 2009

Objectives. This study explored the association between conditional goal setting (CGS; the tendency to view the achievement of high order goals for the self as conditional upon the achievement of lower order goals) and dispositional mindfulness.

Design/methods. CGS and dispositional mindfulness were assessed in 31 depressed patients in a cross‐sectional design.

Results. A significant association was identified between increased dispositional mindfulness and reduced CGS, which remained after controlling for severity of depressed mood.

Conclusions. The results suggest that treatment interventions that increase levels of mindful awareness may have the capacity to reduce CGS in depressed patients.
Regulation of Osteogenesis-Angiogenesis Coupling by HIFs and VEGF
Authors: Schipani Ernestina , Maes Christa , Carmeliet Geert , Semenza Gregg L
Published: June 2009

Bone is a highly vascularized tissue, but the function of angiogenesis in bone modeling and remodeling is still poorly defined, and the molecular mechanisms that regulate angiogenesis in bone are only partially elucidated. Genetic manipulations in mice have recently highlighted the critical role of the hypoxia-inducible-factor/vascular endothelial growth factor pathway in coupling angiogenesis and osteogenesis. In this brief perspective, we review the current understanding of the mechanisms responsible for this coupling. Elucidation of such mechanisms will expand our knowledge of bone development and homeostasis, and it may aid in the design of new therapies for accelerating bone regeneration and repair.
India's Regional and International Support for Democracy: Rhetoric or Reality?
Authors: Cartwright Jan
Published: June 2009

In recent years, Indian leaders have elevated the prominence of democratic rhetoric in their regional and international political discourse. This paper examines India's record of democracy promotion. It argues that India has much to gain by selectively supporting democracy in neighboring countries. Furthermore, participating in multinational efforts at democracy promotion offers India a potential vehicle for global leadership.
China's “Soft” Clash with South Korea: The History War and Beyond
Authors: Chung Jae Ho
Published: June 2009

South Korea's mode of responding to the rise of China is not fixed but continues to evolve. The recent clash over Koguryo historiography provides a sobering example of how easily the symbiotic relationship can be abruptly interrupted. It shows the need for careful management of the bilateral relationship by both Seoul and Beijing.
Economics, History, and the Origins of Vietnam's Post-War Economic Success
Authors: Fforde Adam
Published: June 2009

During the 1990s, skeptical aid donors confronted an example of development “success” in Vietnam. Understanding this requires reflection upon economic conditions in North Vietnam prior to 1975. These conditions created important prerequisites for a successful transition to a market economy, sufficiently guided by local reformists so as not to unduly threaten stability, and sufficiently reflective of realities that it could work.
Contradictions in the Development of Citizenship in Hong Kong: Governance without Democracy
Authors: Ku Agnes Shuk-mei
Published: June 2009

This article discusses the trajectory of citizenship (re-)formation in relation to governance strategies in Hong Kong. Extending Marshall's theory with a notion of democratic citizenship, it shows how the governance strategies become increasingly inadequate and how civil society's new proposals outgrow the conventional model of citizenship.
Perceptions of Anti-Terrorism among Students at China's Guangzhou University: Misinformation or Misinterpretation?
Authors: Shen Simon , Liu Peng
Published: June 2009

By conducting a set of quantitative surveys, this study evaluates the perception of Chinese students on terrorism. Three questions are tackled: (1) how they know about terrorism; (2) how they evaluate terrorist organizations and the U.S., and (3) how they view the corresponding Chinese foreign policy.
Reactive wetting of polycrystalline TiC by molten Zr55Cu30Al10Ni5 metallic glass alloy
Authors: Shen Ping , Lin Qiaoli , Jiang Qichuan , Fujii Hidetoshi , Nogi Kiyoshi
Published: June 2009

The isotherm wetting and spreading behaviors of polycrystalline TiC by molten Zr55Cu30Al10Ni5 alloy were investigated at 1133 to 1253 K in a vacuum by using a modified sessile drop method. The system displays good wettability with the initial and final stable contact angles of 44 to 50° and 10 to 14°, respectively, mildly depending on the temperature. The spreading kinetics follows well defined exponential functions and could be described by a molecular dynamic model. On the other hand, a ZrC reaction layer was formed at the interface. The wetting was primarily promoted by the Zr adsorption at the triple junction and then by the formation of the reaction layer.
Nitrogen function of aluminum-nitride codoped ZnO films deposited using cosputter system
Authors: Lai Li-Wen , Yan Jheng-Tai , Chen Chia-Hsun , Lou Li-Ren , Lee Ching-Ting
Published: June 2009

AlN codoped ZnO films were deposited on sapphire substrates at low temperature using a cosputter system under various N2/(N2 + Ar) flow ratios. To investigate the nitrogen function, the ratio of nitrogen ambient was varied during cosputtering. AlN codoped ZnO films with various crystallographic structures and bonding configurations were measured. With an adequate nitrogen atmosphere deposition condition and postannealing temperature at 450 °C, the p-type conductive behaviors of AlN codoped ZnO films were achieved due to the formation of Zn–N bonds. According to the low-temperature photoluminescence spectra, the binding energy (EA) of 0.16 eV for N acceptors can be calculated. Using time-resolved photoluminescence measurement, the carrier lifetime in AlN codoped ZnO films increases due to the reduction of oxygen vacancies caused by the occupation of adequate nitrogen atoms.
Experimental investigation of Zr-rich Zr–Zr2Ni–(Zr,Ti)2Ni ternary eutectic system
Authors: Lee Dong-Myoung , Sun Ju-Hyun , Kang Dong-Han , Shin Seung-Yong , Lee Chi-Whan
Published: June 2009

As potential substitutes for traditional Ti(Zr)–Cu–Ni-based brazing metals for high strength Ti alloys as well as a study for metallic glass, Zr–Ti–Ni-based alloys have been attracting much attention recently. In this study, the melting temperatures and microstructures of the Zr(Ti)-rich Zr–Ti–Ni alloys with Ni content below 33.3 at.% were systematically studied. A ternary deep eutectic alloy consisting of three phases was found at the composition of Zr50Ti26Ni24 with a solidus temperature of 798 °C and a liquidus temperature of 809 °C, which are significantly lower than the Zr2Ni–(Zr,Ti)2Ni pseudobinary eutectic melting temperature of 850 °C. This ternary eutectic reaction can be presented as L → α-(Zr/Ti) solid solution + Zr2Ni + ternary Laves (Zr,Ti)2Ni.
The scanning electron acoustic microscopy investigation on ferroic materials under local stress
Authors: Song Hongzhang , Li Yongxiang , Zhao Kunyu , Zeng Huarong , Li Guorong , Yin Qingrui
Published: June 2009

In this paper, the responses in the microregion of three ferroic-type materials, such as ferroelectric single crystals (PMN-PT and BaTiO3), ferromagnetic alloy (Fe81Ga19), and ferroelastic alloy (Ni53Mn24Ga23), to local stress induced by Vickers indentations were studied using scanning electron-acoustic microscopy (SEAM), a powerful technique for nondestructive investigation of the microstructure of materials. The responses of ferroelectric domains, magnetic domains, and ferroelastic domains to local stress were successfully observed. These responses possess three major features including the plastic deformation underneath the indenter, the extension of microcracks induced by indentation, and the formation of new lamellar domains within the matrix domain structure. In addition, by using the unique ability of SEAM to image layer by layer, the distributions of residual stress at different depths were obtained. The generation mechanisms of the electron acoustic signals of ferroelectric domains, magnetic domains, and ferroelastic domains are discussed.
Solidified microstructure evolution of Mn-Sb near-eutectic alloy under high magnetic field conditions
Authors: Wang Qiang , Gao Ao , Liu Tie , Liu Feng , Zhang Chao , He Jicheng
Published: June 2009

Mn-90.8 wt%Sb alloys were solidified without and with high magnetic fields to investigate the effects of high magnetic fields on the structure evolution of the alloys. It was found that there were only MnSb/Sb eutectics without any primary phase in the alloy at 0 T, whereas a small amount of primary MnSb dendrites appeared in the MnSb/Sb eutectic matrix when the magnetic flux density was 4.4 T. In magnetic fields of 6.6, 8.8, and 11.5 T, both of two primary phases, i.e., MnSb and Sb, occurred in the matrix. In addition, the volume fraction of these two primary phases increased with increasing magnetic flux density. In magnetic fields of 8.8 and 11.5 T, primary MnSb dendrites aligned parallel to the magnetic field direction and gathered at the edge of the specimens. In contrast, primary Sb dendrites gathered in the center region of the specimens.
Effect of melt temperature on the mechanical properties of bulk metallic glasses
Authors: Kumar Golden , Ohkubo Tadakatsu , Hono Kazuhiro
Published: June 2009

The effect of melt temperature on the structure and mechanical properties of three Zr-based bulk metallic glasses (BMGs)—Zr62Cu17Ni13Al8, Zr55Cu20Ni10Al10Ti5, and Zr52.5Cu17.9Ni14.6Al10Ti5 (Vit105)—has been studied. The results show that the BMGs cast from higher melt temperature exhibit large plastic strains despite their amorphous structure. The samples become macroscopically brittle when the quenched-in crystals form an interconnected microstructure. In contrast to previous studies, there is no notable effect on the Poisson’s ratio (ν) and other elastic constants.
Structural and elastic properties of Cu6Sn5 and Cu3Snfrom first-principles calculations
Authors: Chen Jiunn , Lai Yi-Shao , Yang Ping-Feng , Ren Chung-Yuan , Huang Di-Jing
Published: June 2009

We investigated the elastic properties of two tin-copper crystalline phases, the η′-Cu6Sn5 and ε-Cu3Sn, which are often encountered in microelectronic packaging applications. The full elastic stiffness of both phases is determined based on strain-energy relations using first-principles calculations. The computed results show the elastic anisotropy of both phases that cannot be resolved from experiments. Our results, suggesting both phases have the greatest stiffness along the c direction, particularly showed the unique in-plane elastic anisotropy associated with the lattice modulation of the Cu3Sn superstructure. The polycrystalline moduli obtained using the Voigt-Reuss scheme are 125.98 GPa for Cu6Sn5 and 134.16 GPa for Cu3Sn. Our data analysis indicates that the smaller elastic moduli of Cu6Sn5 are attributed to the direct Sn–Sn bond in Cu6Sn5. We reassert the elastic modulus and hardness of both phases using the nanoindentation experiment for our calculation benchmark. Interestingly, the computed polycrystalline elastic modulus of Cu6Sn5 seems to be overestimated, whereas that of Cu3Sn falls nicely in the range of reported data. Based on the observations, the elastic modulus of Cu6Sn5 obtained from nanoindentation tests admit the microstructure effect that is absent for Cu3Sn is concluded. Our analysis of electronic structure shows that the intrinsic hardness and elastic modulus of both phases are dominated by electronic structure and atomic lattice structure, respectively.
Formation of tough interlocking microstructure in ZrB2–SiC-based ultrahigh-temperature ceramics by pressureless sintering
Authors: Zou Ji , Zhang Guo-Jun , Kan Yan-Mei
Published: June 2009

A self-reinforced ultrahigh-temperature ceramic (UHTC) with elongated ZrB2grains has been successfully densified by pressureless sintering using commercially available ZrB2, SiC, and WC powders as raw materials. Benefiting from the unique interlocking microstructure, this material had improved strength (518 ± 10 MPa) and higher fracture toughness (6.5 ± 0.2 MPa m1/2) compared to ZrB2–SiC ceramics prepared by pressureless sintering. This work provides a new route for tailoring the microstructure and mechanical properties of UHTCs.
Effect ofStreptococcus mutanson mechanical properties of human dental structures
Authors: Chang Shou-Yi , Chung Ren-Jei , Chou Fang-Cheng , Hsiao Hsiang-Long , Hsu Hung-Bin
Published: June 2009

In this study, the mechanical properties of human dental structures have been investigated by using instrumented nanoindentation. Immersion in solutions containingStreptococcus mutans, which is the principal cause of dental caries, was applied to tooth specimens to clarify its effect on the microstructure and mechanical properties of the dental structures. With an extended time of up to 16 h, the pH value of theS. mutanssolutions dropped from 7.3 to 5.8. Therefore, after immersion in theS. mutanssolutions for 16 h, slight erosions of the dental structures began; after 64 h, severe tooth decay occurred with obviously etched dental features. After 128 h, the elastic modulus of enamel and dentine dropped to 85 and 67%, respectively, of the original values of untreated specimens, and the hardness dropped to 88 and 55%, respectively.
Synthesis and field-responsive properties of SrTiO3 nanoparticle/polymer hybrid
Authors: Umeda Junji , Sakamoto Wataru , Yogo Toshinobu
Published: June 2009

Nanocrystalline strontium titanate (SrTiO3) particle/polymer hybrid was synthesized from metal–organics and 2-(methacryloyloxy)ethyl maleate (MMEM). SrTiO3 precursor was prepared from strontium isopropoxide and titanium isopropoxide in 2-methoxyethanol. Nanocrystalline SrTiO3 particle/poly-MMEM hybrid was formed by hydrolysis followed by reaction with MMEM. The crystallinity of SrTiO3 particles depended on the amount of water for hydrolysis. The nanocrystalline particles were identified to be strontium titanate by x-ray diffraction. Fourier transform infrared spectroscopy and x-ray photoelectron spectroscopy showed the presence of the chemical bond between SrTiO3 particles and the organic matrix. The fluid consisting of SrTiO3 particle/poly-MMEM and silicone oil revealed a yield stress dependent on various conditions, such as hydrolysis conditions and applied field. The hybridization was found to have a pronounced effect on the electrorheological properties of the nanoparticle/polymer-based system.
Structural and optical properties of nanocrystalline ZnO thin films derived from clear emulsion of monodispersed ZnO nanocrystals
Authors: Inoguchi Masashi , Suzuki Keigo , Tanaka Nobuhiko , Kageyama Keisuke , Takagi Hiroshi
Published: June 2009

In this study, the dense films of well-crystallized ZnO nanocrystals were successfully prepared by direct spin-coating of the colloidal solution of ZnO nanoparticles derived from the microemulsion method. The average grain sizes in the films were reasonably controlled in the range from 6.5 to 34.3 nm by simply changing the annealing temperatures. The increase in band gap energies was found in the size region less than 13.3 nm, finally resulting in 3.47 eV for the average size of 6.5 nm. The photoluminescence spectra at room temperature showed intense ultraviolet (UV) emission with faint green luminescence. The Stokes shifts of the films were estimated to be one or two orders of magnitude smaller than those of the conventional ZnO nanocrystalline films, suggesting the well crystallization and slight amounts of lattice defects in the ZnO nanoparticles. These excellent features may be favorable to make high-performance optical application such as UV emitting devices.
Microwave-assisted synthesis of various gallium oxyhydroxide nanorods and their controllable conversion into different gallium oxide polymorphs
Authors: Ge Suxiang , Zhang Lizhi , Jia Huimin , Zheng Zhi
Published: June 2009

Various α-GaOOH nanorods were synthesized through a microwave-assisted method at 80 °C. In the synthesis, Ga(NO3)3 was used as the gallium source, and urea, L-cysteine, and EDTA disodium salt were used as the additives. The thermal decomposition of the as-prepared α-GaOOH nanorods could selectively produce α-, β-, and ε-Ga2O3 nanorods. X-ray diffraction, scanning electron microscopy, transmission electron microscopy, high-resolution transmission electron microscopy, and cathodoluminescence were used to characterize the resulting samples. On the basis of characterization results, the possible growth mechanisms of these various GaOOH nanorods were proposed. This study provides a controllable method to prepare various gallium oxyhydroxide and gallium oxide nanorods.
Synthesis and oxidation stability of monosized and monocrystalline Pr nanoparticles
Authors: Kala Shubhra , Mehta Bodh Raj , Kruis Frank Einar , Singh Vidya Nand
Published: June 2009

This study reports the synthesis of monosized Pr nanoparticles with a controllable size ranging from 5 to 20 nm. Pr agglomerates generated by a spark generator first size-selected by a differential mobility analyzer and subsequently sintered in-flight at different temperatures result in spherical and monocrystalline Pr nanoparticles. The dependence of size and size distribution of Pr nanoparticles has been studied as a function of deposition parameters related to spark generator, differential mobility analyzer, and sintering. Transmission electron microscopy, energy-dispersive x-ray analysis, glancing angle x-ray diffraction, and x-ray photoelectron spectroscopy studies confirm that initial Pr agglomerates and the resulting nanoparticles are metallic with d-hexagonal structure and remain stable in air during post-deposition exposure. Incomplete or partially sintered nanoparticles were found to be oxidized, resulting in the formation of amorphous oxide phase due to enhanced oxidation at grain boundaries.
NMR and Raman spectroscopic characterization of single walled carbon nanotube composites of polybutadiene
Authors: Bennett George D. , Greenbaum Steve G. , Owens Frank J.
Published: June 2009

Significant shifts of the frequency of the Raman spectra of the tangential mode of single walled carbon nanotubes (SWNTs) and fluorinated tubes (FSWNTs) in composites of polybutadiene (PB) were observed relative to the pristine SWNTs indicative of the interaction between the polymer and the SWNTs. Proton NMR line width measurements demonstrate partial suppression of polymer segmental motion for both types of nanotube composites and spin-lattice relaxation results indicate that short time-scale localized motions are also affected by SWNT inclusion, more so for FSWNTs. Hardness measurements as a function of wt% SWNTs and FSWNTs in the polymer show larger enhancements of hardness in the composite with the fluorinated tubes.
A new viewpoint to the mechanism for the effects of melt overheating on solidification of Pb-Bi alloys
Authors: Zu Fang-Qiu , Chen Jie , Li Xian-Fen , Mao Li-Na , Liu Yong-Chi
Published: June 2009

The effects of melt overheating treatment on solidification of Pb-Bi alloys were studied from the viewpoint of liquid-liquid structure change (LLSC). Anomalous temperature dependence of internal friction, electrical resistivity, and entropy of liquid Pb-Bi alloys suggested that discontinuous LLSC occurred within about 520–740 °C, based on which the solidification experiments were carried out with different states of Pb-Bi melts. The results revealed that the LLSC affected the solidification behavior and microstructures significantly, that is, the enlarged undercooling, increased nucleation rate, and refined and improved morphologies were brought about when solidifying from the melt experienced LLSC. It is assumed that the LLSC changed the energy constitution of the melt system, and further affected the effective partition coefficient, thermodynamics, and kinetics of crystal growth, then finally altered the solidification behavior and solidified microstructures. This work brings a novel insight into the effect of melt overheating treatment on solidification, by which it could be more effective to manipulate melts.
Magnetic and electronic transport properties of nanocomposites of superconducting Mo carbides’ nanoparticles embedded in a ferromagnetic carbon matrix
Authors: Wang Zhen H. , Li Da , Geng Dianyu , Ma Song , Liu Wei , Zhang Z.D.
Published: June 2009

The electronic transport and magnetic properties of nanocomposites, in which nanoparticles of superconducting (SC) molybdenum carbides are embedded in a ferromagnetic (FM) carbon matrix to form a three-dimensional SC-FM network, are studied. The high-resolution transmission electron microscope observation shows that the carbon in the nanocomposites is in both ordered and disordered forms. The magnetic properties of the nanocomposites are ruled by the ferromagnetic carbon matrix. The temperature dependence of electrical resistivity of the nanocomposites is dominated by the carbon matrix, showing the semi-conductivity. The special I-V curves near the zero voltage bias of the nanocomposites are observed at low temperatures, due to the influence of contact barriers between molybdenum carbides and the carbon matrix.
Effects of Antiepileptic Drug Substitutions on Epileptic Events Requiring Acute Care
Authors: Rascati Karen L. , Richards Kristin M. , Johnsrud Michael T. , Mann Teresa A.
Published: June 2009

Study Objectives. To determine the odds of antiepileptic drug substitution among patients who had an epileptic event requiring acute care—ambulance service, emergency department visit, or hospitalization—relative to patients who did not have an event, and to compare these results with those from a recent study involving a similar method but different patients.

Design. Case‐control analysis.

Data Source. United States health care claims from the PharMetrics database.

Patients. A cohort of patients aged 12–64 years with a primary diagnosis of epilepsy between October 1, 2005, and December 31, 2006; 991 cases (patients who experienced an epileptic event requiring acute care) and 2973 controls (patients who did not have an event) were matched in a 1:3 ratio for sex, age, and type of epilepsy.

Measurements and Main Results. Using discordant pairs analysis, we calculated the odds ratio of an epileptic event that required acute care occurring in patients whose antiepileptic drug underwent substitution to an A‐rated (therapeutically equivalent) alternative (switch from branded product to generic, generic to branded, or generic to generic) versus those whose drugs were not substituted. For matched data, 109 (11.0%) of 991 cases had an A‐rated antiepileptic drug substitution in the 6 months before the event, whereas only 186 (6.3%) of 2973 controls had a substitution (odds ratio 1.84, 95% confidence interval 1.44‐2.36). Our results were similar to those of a previous study involving a different patient database, which showed substitution rates of 11.3% for cases versus 6.5% for controls (odds ratio 1.81, 95% confidence interval 1.25‐2.63). Our sensitivity analyses were robust, and we found a temporal relationship in that numerous substitutions occurred in the month before the acute event.

Conclusion. Patients who had an epileptic event requiring acute care were about 80% more likely than matched controls without an acute event to have recently had an antiepileptic drug substitution. Our replication of a previously published case‐control analysis revealed a similar association between substitution involving A‐rated antiepileptic drugs and subsequent epileptic events requiring acute care, thereby lending credibility to the findings.