bluuebunny/crossref_metadata_2025 huggingface dataset:
Green composites: An overview
Authors: Zini Elisa , Scandola Mariastella
Published: November 2011

The use of natural fibers to reinforce polymers is a well‐established practice, and biocomposites are increasingly used in sectors such as automotive and construction. Green composites are a specific class of biocomposites, where a bio‐based polymer matrix is reinforced by natural fibers, and they represent an emerging area in polymer science. This work discusses the environmental benefits deriving from the use of natural fibers in polymer composites and from substitution of oil‐derived polymers by bio‐based polymers as matrix material. New trends in the selection of natural fibers, that is, from waste rather than from valuable crops are described. Recently developed thermoplastic and thermosetting bio‐based polymers are reviewed, and commercially available green composites obtained thereof are discussed. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers
Rheological behavior of nanofibrillated cellulose/acrylic polymer nanocomposites: Effect of melt extrusion
Authors: Besbes Iskander , Magnin Albert , Boufi Sami
Published: November 2011

Nanocomposite films based on nanofibrillated cellulose (NFC) and acrylic latex were prepared by film casting and their melt rheology was investigated under dynamic conditions in both the linear and the nonlinear regimes. The addition of cellulose nanofiller increased the storage modulus G′ and the dynamic viscosities η* of the nanocomposites monotonically, with NFC contents up to 6wt%. In addition, a transition from liquid‐like to solid‐like viscoelastic behavior was observed up to 1wt% of the added NFC with a terminal plateau in the low‐frequency range. This was explained in terms of the formation of an interconnected network involving the filler. After melt extrusion, a considerable change in the rheological properties was observed, with a major downward shift in the magnitude of G′ vs. the frequencies along with an upward shift to higher strain in the linear viscoelastic range. Such a transition was attributed to the irreversible break‐down and disruption of the NFC network. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers
A geometry force field which converts low‐resolution X‐ray models to structures with properties found at ultra high resolution
Authors: McMartin Colin
Published: November 2011

A geometry optimization force field was developed using ultra high‐resolution structures and tested using high‐ and low‐resolution X‐ray structures. Protein and small molecule X‐ray data was used. When applied to ultra high‐resolution structures the force field conserves the internal geometry and local strain energy. When applied to low‐resolution structures there is a small change in geometry accompanied by a large drop in local strain energy. Although optimization causes only small structural changes in low‐resolution X‐ray models, it dramatically modifies profiles for hydrogen bonding, Van der Waals contact, bonded geometry, and local strain energy, making them almost indistinguishable from those found at high resolution. Further insight into the effect of the force field was obtained by comparing geometries of homologous proteins before and after geometry optimization. Optimization causes homologous regions of structures to become similar in internal geometry and energies. Once again, the changes only require small atomic movements. These findings provide insights into the structure of molecular complexes. The new force field contains only short‐range interatomic potential functions. Its effectiveness shows that local geometries are determined by short‐range interactions which are well modeled by the force field. Potential applications of this study include detection of possible structural errors, correction of errors with minimal change in geometry, improved understanding and prediction of the effects of modifying ligands or proteins, and computational addition of structural water.
MalPEFinder: fast and retrospective assessment of data breaches in malware attacks
Authors: Liu Shun‐Te , Chen Yi‐Ming
Published: November 2011

A successful data breach is often caused by malware installed by attackers. In a large‐scale computer environment, it is difficult and costly for information technology managers to identify the victims and to assess the scope of the data breach when a malware attack occurs. Therefore, a quick and retrospective mechanism that can find victims is required. One such technology is Search. However, most search techniques are not designed for searching executable files; indeed, they become worse in identifying malware files because of polymorphism and/or metamorphism.

In this paper, we propose a portable executable format file search mechanism, called MalPEFinder. Instead of searching malware files, this mechanism searches the malware‐related files retrospectively. Based on these files and their ownership, MalPEFinder can locate malware files on a large scale quickly. Furthermore, the possibly breached files also can be identified. A MalPEFinder prototype has been implemented on the hadoop platform in order to perform three functions: (i) searching retrospectively; (ii) protecting evidence against tampering; and (iii) dealing with future data growth. We used 72 malware to evaluate the accuracy and efficiency of our system. The experimental results show that MalPEFinder has a higher detection rate as well as a lower false positive rate than the famous splunk tool. Copyright © 2011 John Wiley & Sons, Ltd.
Chemiresistive Sensing with Chemically Modified Metal and Alloy Nanoparticles
Authors: Ibañez Francisco J. , Zamborini Francis P.
Published: November 2011

This review describes the use of chemically modified pure and alloyed metal nanoparticles for chemiresistive sensing applications. Chemically modified metal nanoparticles consist of a pure or alloyed metallic core with some type of chemical coating. Researchers have studied the electronic properties of 1D, 2D, and 3D assemblies of chemically modified metal nanoparticles, and even single individual nanoparticles. The interaction with the analyte alters the conductivity of the sensitive material, providing a signal to measure the analyte concentration. This review focuses on chemiresistive sensing of a wide variety of gas‐ and liquid‐phase analytes with metal nanoparticles coated with organothiols, ions, polymers, surfactants, and biomolecules. Different strategies used to incorporate chemically modified nanoparticles into chemiresistive sensing devices are reviewed, focusing on the different types of metal and alloy compositions, coatings, methods of assembly, and analytes (vapors, gases, liquids, biological materials), along with other important factors.
Synthesis and Characterization of Organotin Compounds of a New Schiff Base Ligand with α‐Oxoglutaric Acid Isonicotinyl Hydrazone
Authors: Li Jing , Yin Handong , Hong Min
Published: November 2011

Organotin compounds are a recurring motif in organometallic chemistry. The syntheses and characterization of new diorganotin compounds with α‐oxoglutaric acid isonicotinyl hydrazone are described, prepared compounds were characterized by elemental analysis, UV/Vis, 1H, and 13C NMR spectroscopy, and X‐ray diffraction. They both have a distorted pentagonal bipyramidal arrangement, with a heptacoordinated central tin atom. Compound 1 presents a centrosymmetric dinuclear framework. Interestingly, intermolecular O–H···N and O–H···O hydrogen bonds contribute to the two‐dimensional network. Compound 2 is a simple mononuclear compound, which exhibits a rare one‐dimensional chain constructed by intermolecular O–H···Cl and N–H···O hydrogen bonds.
Synthesis and Properties of Organosilicon Quaternary Salts Surfactants
Authors: Li Junying , Zhang Qingsi , Wang Yan , Zhang Wenyu , Li Tianduo
Published: November 2011

Diethyl‐benzyl‐[3‐methyldimethoxyl)]silpropyl ammonium chloride (DEBSAC) was synthesized from N,N‐diethyl‐aminopropyl‐methyldimethoxysilane (DEAPMDES) and benzyl chloride. Diethyl‐2,3‐epoxypropyl‐[3‐methyldimethoxyl)] silpropyl ammonium chloride (DEEPSAC) was synthesized from DEAPMDES and epoxy chloropropane. Trimethyl‐[3‐methyldimethoxyl)] silpropyl ammonium chloride (TMSAC) was synthesized from trimethylamine and γ‐chloropropylmethyldimethoxysilane (CPMDMS). The products were characterized by 1H NMR, 13C NMR, and IR. The surface tension measurements showed that the organosilicon quaternary salts exhibit a lower surface tension and a lower critical micelle concentration (CMC) than the hydrocarbon counterparts. The plate count method experiments illustrated that DEEPSAC has a better degree of antibacterial activity against Escherichia coli than DEBSAC. The solubilizing effects of the organosilicon quaternary salts on organosilicone were studied by pseudo‐ternary phase diagrams of synthesized products/cosurfactant(n‐butanol)/water/octamethylcyclotetrasiloxane. The solubilizing activities decreased in the order of TMSAC > DEBSAC > DEEPSAC.
Pictorial Essay: Pitfalls in Magnetic Resonance Imaging of the Shoulder
Authors: Goh Chin K. , Peh Wilfred C.G.
Published: November 2011

Numerous imaging pitfalls of normal variants due to imaging technique and artifacts can be seen on routine magnetic resonance imaging of the shoulder. Familiarity with these pitfalls is crucial to avoiding diagnostic errors. Understanding of the common causes of shoulder imaging artifacts will enable the radiologist to make rational changes in imaging technique to eliminate or reduce the effects of artifacts on magnetic resonance images. This pictorial essay highlights possible pitfalls that arise from imaging techniques, imaging artifacts, and normal variations, and how they may be recognized.
Rise of xenophobic nationalism in Europe: A case of Slovenia
Authors: Kuhelj Alenka
Published: November 2011

The article focuses on rise of nationalism and xenophobia in Slovenia. It starts by considering the issue of unrecognized minorities in Slovenia (former Yugoslavia nations) that have no minority rights, despite being large groups, as many international organizations for the protection of minorities have pointed out. A particular issue in this relation for Slovenia is the ‘Erased’ – the individuals who did not acquire Slovenian citizenship when Slovenia seceded from federal Yugoslavia – and despite the European Court of Human Rights (ECHR) decision, the Slovenian state has still not recognized their rights, which were violated in the post-independence period. The article also examines two other minorities in Slovenia, the Jews and the Roma. The article finds Slovenia to be a closed, non-globalised society which, in spite of its constitutional declaration to protect the rights of minorities and other national communities, is seeking to retain a politically and culturally homogeneous nation state.
Early protein malnutrition disrupts cerebellar development and impairs motor coordination
Authors: Ranade Sayali C. , Sarfaraz Nawaz Md. , Kumar Rambtla Pavan , Rose Applonia J. , Gressens Pierre , Mani Shyamala
Published: November 2011

Maternal malnutrition affects every aspect of fetal development. The present study asked the question whether a low-protein diet of the mother could result in motor deficits in the offspring. Further, to examine whether cerebellar pathology was correlated with motor deficits, several parameters of the postnatal development of the cerebellum were assayed. This is especially important because the development of the cerebellum is unique in that the time scale of development is protracted compared with that of the cortex or hippocampus. The most important result of the study is that animals born to protein-deficient mothers showed significant delays in motor development as assessed by rotarod and gait analysis. These animals also showed reduced cell proliferation and reduced thickness in the external granular layer. There was a reduction in the number of calbindin-positive Purkinje cells (PC) and granular cells in the internal granular layer. However, glial fibrillary acidic protein-positive population including Bergmann glia remained unaffected. We therefore conclude that the development of the granular cell layer and the PC is specifically prone to the effects of protein malnutrition potentially due to their protracted developmental period from approximately embryonic day 11 to 13 until about the third postnatal week.
European adolescents’ level of perceived stress is inversely related to their diet quality: the Healthy Lifestyle in Europe by Nutrition in Adolescence study
Authors: De Vriendt Tineke , Clays Els , Huybrechts Inge , De Bourdeaudhuij Ilse , Moreno Luis A. , Patterson Emma , Molnár Dénes , Mesana María I. , Beghin Laurent , Widhalm Kurt , Manios Yannis , De Henauw Stefaan
Published: November 2011

As stress is hypothesised to influence dietary behaviour, the relationship between perceived stress and diet quality in European adolescents was investigated. Within the Healthy Lifestyle in Europe by Nutrition in Adolescence study, adolescents (n 704, aged 12–17 years) from schools in five European cities (Ghent, Stockholm, Zaragoza, Athens and Vienna) completed a 2 d 24 h dietary recall assessment and an Adolescent Stress Questionnaire. Measurements and information were taken on height, weight, pubertal stage, parental education level, the level of moderate-to-vigorous physical activity (MVPA) and sleep duration. The Diet Quality Index for Adolescents (DQI-A) was calculated from the dietary data, which comprised three components reflecting dietary diversity, quality and equilibrium. Hierarchical linear models were performed to investigate the relationship between the adolescents' level of perceived stress and the DQI-A and its components, adjusting for relevant covariates (age, BMI z-score, pubertal stage and parental education). These models were additionally adjusted for MVPA or sleep duration. In both boys and girls, perceived stress was a significant independent negative predictor for their overall DQI-A. This inverse relationship was observed for all dietary components, except for dietary diversity in boys, and it was unaltered when additionally adjusted for MVPA or sleep duration. The observed inverse relationship between stress and diet quality within these European adolescents supports the hypothesis that stress influences dietary behaviour, thus emphasising the need for preventive stress-coping strategies for adolescents.
Narrative Remains: Articulating Indian Identities in the Repatriation Context
Authors: Johnson Greg
Published: November 2011

This article pursues two basic agendas. My primary purpose is to explore the contours of repatriation language as spoken by Native Americans directly participating in repatriation processes. To this end, I argue that a first step entails a critical assessment of the terms and assumptions by which repatriation discourse is framed by observers, participant observers included. Therefore, the first section of this article works toward a critical theory of repatriation discourse, with particular reference to religious language and narratives of identity. I make a case for approaching repatriation discourse as a rhetorical field. Questions I ask include: Who speaks? Under what constraints? With what possibilities? Addressing these questions, among others, I advocate an analytical approach to repatriation that is both specific and frank in exploring the ways group boundaries are shaped and reshaped through narrative.
Middle Jurassic turtles from the Sichuan Basin, China: a review
Authors: TONG HAIYAN , DANILOV IGOR , YE YONG , OUYANG HUI , PENG GUANGZHAO
Published: November 2011

The turtle fauna of the Middle Jurassic Xiashaximiao Formation in the Sichuan Basin and the type series ofChengyuchelys baenoidesYoung & Chow, 1953 are revised. By the absence of a mesoplastron and other shell characters, both the holotype and paratype ofChengyuchelys baenoidesbelong to the family Xinjiangchelyidae and come probably from the Upper Jurassic Shangshaximiao Formation. The Middle Jurassic turtle assemblage of the Sichuan Basin is composed of two entities: the Bashuchelyidae fam. nov. (Bashuchelysgen. nov.,Chuannanchelysgen. nov.) andProtoxinjiangchelysgen. nov. on the one hand, andSichuanchelyson the other hand, with the former as the dominant group. Bashuchelyids and xinjiangchelyids are closely related to one another, whileSichuanchelysis more primitive and has no shared apomorphic features with bashuchelyids. The whole assemblage appears to be endemic to the Sichuan Basin at genus level and distinct from the Late Jurassic turtle fauna of the same basin in its relict nature and absence of the Polycryptodira.
Caste and power: An ethnography in West Bengal, India
Authors: ROY DAYABATI
Published: November 2011

This paper explores the institution of caste and its operation in a micro-level village setting of West Bengal, an Indian state, where state politics at grass roots level is vibrant with functioning local self-government and entrenched political parties. This ethnographic study reveals that caste relations and caste identities have overarching dimensions in the day-to-day politics of the study villages. Though caste almost ceases to operate in relation to strict religious strictures, under economic compulsion the division of labour largely coincides with caste division. In the cultural–ideological field, the concept of caste-hierarchy seems to continue as an influencing factor, even in the operation of leftist politics.
Low prevalence of major depressive disorder in Taiwanese adults: possible explanations and implications
Authors: Liao S.-C. , Chen W. J. , Lee M.-B. , Lung F.-W. , Lai T.-J. , Liu C.-Y. , Lin C.-Y. , Yang M.-J. , Chen C.-C.
Published: November 2011

Background

This study examined the prevalence of major depressive disorder (MDD), and the correlations and co-morbid conditions associated with MDD, in the adult Taiwanese population, which a previous estimate in the 1980s had found to be at the lower end of the spectrum worldwide. Possible explanations for the reported low prevalence of MDD were evaluated.

Method

As part of a survey of common psychiatric disorders in a nationally representative sample of individuals aged ⩾18 years who were non-institutionalized civilians in Taiwan, a face-to-face interview using the paper version of the World Mental Health Survey of the World Health Organization (WHO) Composite International Diagnostic Interview (WMH-CIDI) was conducted between 2003 and 2005. Functional impairment and help-seeking behaviors were compared between Taiwanese subjects with MDD and their counterparts in the USA.

Results

Among the 10 135 respondents, the lifetime prevalence of MDD was 1.20% [standard error (s.e.)=0.2%]. Individuals who were divorced or widowed, aged ⩽40 years, and female were at increased risk, whereas rural residents were at lower risk for MDD. The proportion of MDD cases co-morbid with other psychiatric disorders in this study was much lower than in the US study. Only one-third of Taiwanese individuals with MDD sought help despite having twice the number of lost workdays compared with the US sample.

Conclusions

Despite the low prevalence of MDD in Taiwanese adults, the pattern of low help-seeking behavior and profound functional impairment indicates much room for improvement in the early detection of and intervention in major depression in this population.
La géographie du vieillissement au Canada atlantique: une analyse sous l’angle des disparités territoriales au cours de la période 1981–2006
Authors: Simard Majella
Published: November 2011

Following the example of other Canadian provinces, those in Atlantic Canada are affected, albeit to a lesser degree, by the increase in the number of persons aged 65 or over, a trend that we can define as gerontogrowth. In addition, this region of Canada seems particularly affected by the trend of an aging population, that is, the rise in the proportion of people in the total population aged 65 or more. For example, on a national scale, New Brunswick is the third oldest province according to the last five-year period (2001–2006), having advanced from the fourth position it held between 1981 and 2001 and from the fifth position occupied between 1971 and 1981. In addition, these trends evolve in different manners in different places, contrasts that are strongest at the regional and local level. The goal of this article is to examine the strength of these disparities during the period 1981 to 2006 and to identify some potential solutions for a territorial development strategy for seniors.
The relation between the working memory skills of sign language interpreters and the quality of their interpretations
Authors: VAN DIJK RICK , CHRISTOFFELS INGRID , POSTMA ALBERT , HERMANS DAAN
Published: November 2011

In two experiments we investigated the relationship between the working memory skills of sign language interpreters and the quality of their interpretations. In Experiment 1, we found that scores on 3-back tasks with signs and words were not related to the quality of interpreted narratives. In Experiment 2, we found that memory span scores for words and signs under oral articulatory suppression were related to the quality of interpreted narratives. We argue that the insensitivity to articulatory suppression in memory span tasks reflects the interpreters' ability to bind information from multiple sources in episodic memory. This enhanced ability leads to less reliance on the retention of information from the source language in memory during interpreting, and will positively affect the quality of interpretations (Padilla, Bajo & Macizo, 2005). Finally, in contrast to previous studies on the memory spans for signs and words (Hall & Bavelier, 2010), we found that the memory spans scores for spoken words and signs were equally large. We argue that the use of a large set of phonologically complex stimuli in the present study may have stimulated participants to use a speech-based code to store and retain the signs in short-term memory.
Prevalence and risk factors for self-reported diabetes among adult men and women in India: findings from a national cross-sectional survey
Authors: Agrawal Sutapa , Ebrahim Shah
Published: November 2011

Objective

We examined the distribution of diabetes and modifiable risk factors to provide data to aid diabetes prevention programmes in India.

Design

Population-based cross-sectional survey of men and women included in India's third National Family Health Survey (NFHS-3, 2005–2006).

Setting

The sample is a multistage cluster sample with an overall response rate of 98 %. All states of India are represented in the sample (except the small Union Territories), covering more than 99 % of the country's population.

Subjects

Women (n 99 574) and men (n 56 742) aged 20–49 years residing in the sample households.

Results

Prevalence of diabetes was 1598/100 000 (95 % CI 1462, 1735) among men and 1054/100 000 (95 % CI 974, 1134) among women in India. Rural–urban and marked geographic variation were found with higher rates in south and north-eastern India. Weekly and daily fish intake contributed to a significantly higher risk of diabetes among both women and men. Risks of diabetes increased with increased BMI, age and wealth status of both women and men, but no effects of the consumption of milk/curd, vegetables, eggs, television watching, alcohol consumption or smoking were found. Daily consumption of pulse/beans or fruits was associated with a significantly reduced risk of diabetes among women, whereas non-significant inverse associations were observed in the case of men.

Conclusions

Prevalence was underestimated using self-reports. The wide variation in self-reported diabetes is unlikely to be due entirely to reporting biases or access to health care, and indicates that modifiable risk factors exist. Prevention of diabetes should focus on obesity and target specific socio-economic groups in India.
Three-Dimensional Analysis by Electron Diffraction Methods of Nanocrystalline Materials
Authors: Gammer Christoph , Mangler Clemens , Karnthaler Hans-Peter , Rentenberger Christian
Published: November 2011

To analyze nanocrystalline structures quantitatively in 3D, a novel method is presented based on electron diffraction. It allows determination of the average size and morphology of the coherently scattering domains (CSD) in a straightforward way without the need to prepare multiple sections. The method is applicable to all kinds of bulk nanocrystalline materials. As an example, the average size of the CSD in nanocrystalline FeAl made by severe plastic deformation is determined in 3D. Assuming ellipsoidal CSD, it is deduced that the CSD have a width of 19 ± 2 nm, a length of 18 ± 1 nm, and a height of 10 ± 1 nm.
The 2008 United States-India Nuclear Co-operation Agreement and the Work of the International Law Commission on International Liability for Injurious Consequences Arising Out of Acts not Prohibited by International Law
Authors: BARNIDGE Robert P.
Published: November 2011

This article examines the 2008 Agreement for Co-operation Between the Government of the United States of America and the Government of India Concerning Peaceful Uses of Nuclear Energy [“123 Agreement”] within the context of the International Law Commission's (ILC) work on international liability for injurious consequences arising out of acts not prohibited by international law. Attention is paid to three issues in particular, namely how international environmental law has developed to interact with vaguely worded environmental protection provisions, such as those in the 123 Agreement, and the role of experts in this regard, the issue of civil nuclear liability, and the question of what international law might require for environmental impact assessments under the 123 Agreement to pass muster.
In-silico analysis of human IGFBP-4 involved in cardiovascular diseases
Authors: MuniKumar Manne , Roopesh Kavali , Umamaheswari Amineni
Published: November 2011

Cardiovascular disease is the major cause of disability and premature death throughout the world and contributes substantially to the escalating costs of health care. Insulin like growth factor binding protein 4 (IGFBP-4) mainly belongs to the family of IGFB protein. Over expression of IGFBP-4 leads to cardiovascular diseases namely stroke, acute myocardial infarction and heart failure. IGFBP-4 serves as an effective drug target against cardiovascular disease. Hence, ligand based virtual screening was pursued in the present study to propose potential inhibitors of IGFBP-4. Two published inhibitors were selected to initiate high throughput virtual screening from small molecule databases namely, NCI, ChemBank, ChemPDB, AKos GmbH, Asinex Ltd and KEGG ligand. The structures listed through database search were docked with IGFBP-4 using virtual screening workflow of Maestro v9.2. Three leads that showed better binding affinity and good correlation than two published inhibitors were proposed as potential IGFBP-4 inhibitors. The three proposed leads showed good pharmacological properties in comparison to the two existing inhibitors for next generation drug designing against cardiovascular diseases.
Hydro tropes as promoters in soap flotation
Authors: Khadri Abubakar , P Vijay Kumar , Dassin Yasser , Gowda Prabhulingaiah , DMR Sekhar
Published: November 2011

Soaps, the salts of fatty acids are generally used as collectors in the flotation process to separate salt type minerals. Some times light diesel oil is mixed with soaps and the emulsion is used as collector. Addition of detergents to soaps not only enhances the collector efficiency but also reduces the consumption of soap. Urea a known hydro trope is found to improve the flotation efficiency of soaps. Our current testing is indicating that other hydro tropes such as tri sodium citrate and sodium salicylate are also effective in improving the flotation efficiency of soap and also the soap-LDO emulsion.
Controlled synthesis of radiolabelled amine methacrylate water-soluble polymers with end-groups of varying hydrophobicity and studies of adsorption behaviour
Authors: Long Mark , Thornthwaite David W. , Rogers Suzanne H. , Livens Francis R. , Rannard Steve P.
Published: November 2011

Radioactive initiators of increasing hydrophobicity, including fluorescent initiators, have been used to conduct the ambient ATRP of poly(2-(diethylamino)ethyl methacrylate) and the behaviour of the resultant polymers has been monitored with respect to surface adsorption using radio-techniques; considerable effects of end group type were observed.
Correlation between symmetry-selective transport and spin-dependent resonant tunneling in fully epitaxial Cr/ultrathin-Fe/MgO/Fe(001) magnetic tunnel junctions
Authors: Niizeki Tomohiko , Sukegawa Hiroaki , Mitani Seiji , Tezuka Nobuki , Inomata Koichiro
Published: November 2011

Spin-dependent resonant tunneling was investigated in fully epitaxial Cr(001)/ultrathin Fe(001)/MgO(001)/Fe(001) pseudo double-barrier magnetic tunnel junctions (MTJs) by varying structural coherence of the MgO barrier through postdeposition annealing and Mg layer insertion. It was clearly demonstrated that not only the flatness of the Fe quantum-well layer, but also the structural coherence of the MgO barrier caused the appearance of sharp resonant conductance peaks which were not obtained for spin-dependent resonant tunneling in amorphous AlO-barrier MTJs. The symmetry-selective transport via MgO barrier plays a crucial role for the resonant tunneling as well as large tunneling magnetoresistance.
Electrical signal-to-noise ratio improvement in indirect detection of mid-IR signals by wavelength conversion in silicon-on-sapphire waveguides
Authors: Huang Y. , Tien E. K. , Gao S. , Kalyoncu S. K. , Song Q. , Qian F. , Adas E. , Yildirim D. , Boyraz O.
Published: November 2011

Planar waveguide devices based on silicon-on-sapphire are emerging as a bridge between mid-infrared (IR) and near-IR wavelength through frequency conversion process. We analyze the limits of indirect detection of mid-IR signals by wavelength conversion in such waveguides and investigate signal-to-noise ratio improvement that is attainable with respect to direct detection using state of the art commercial detectors. Our calculation shows that, in addition to room temperature and high speed operation, the proposed indirect detection can improve the electrical signal-to-noise ratio up to 40 dB compared to direct detection by PbSe, HgCdTe, and InSb detectors, especially in detection of weak mid-IR signals.
Dissipative quantum transport in silicon nanowires based on Wigner transport equation
Authors: Barraud Sylvain
Published: November 2011

In this work, we present a one-dimensional model of quantum electron transport for silicon nanowire transistor that makes use of the Wigner function formalism and that takes into account the carrier scattering. Effect of scattering on the current-voltage (I-V) characteristics is assessed using both the relaxation time approximation and the Boltzmann collision operator. Similarly to the classical transport theory, the scattering mechanisms are included in the Wigner formulation through the addition of a collision term in the Liouville equation. As compared to the relaxation time, the Boltzmann collision operator approach is considered to be more realistic because it provides a better description of the scattering events. Within the Fermi golden rule approximation, the standard collision term is described for both acoustic phonon and surface-roughness interactions. It is introduced in the discretized version of the Liouville equation to obtain the Wigner distribution function and the current density. The model is then applied to study the impact of each scattering mechanism on short-channel electrical performance of silicon nanowire transistors for different gate lengths and nanowire widths.
Low beta confinement in a Polywell modelled with conventional point cusp theories
Authors: Carr Matthew , Gummersall David , Cornish Scott , Khachan Joe
Published: November 2011

The magnetic field structure in a Polywell device is studied to understand both the physics underlying the electron confinement properties and its estimated performance compared to other cusped devices. Analytical expressions are presented for the magnetic field in addition to expressions for the point and line cusps as a function of device parameters. It is found that at small coil spacings, it is possible for the point cusp losses to dominate over the line cusp losses, leading to longer overall electron confinement. The types of single particle trajectories that can occur are analysed in the context of the magnetic field structure which results in the ability to define two general classes of trajectories, separated by a critical flux surface. Finally, an expression for the single particle confinement time is proposed and subsequently compared with simulation.
Influence of cross-section geometry and wire orientation on the phonon shifts in ultra-scaled Si nanowires
Authors: Paul Abhijeet , Luisier Mathieu , Klimeck Gerhard
Published: November 2011

Engineering of the cross-section shape and size of ultra-scaled Si nanowires (SiNWs) provides an attractive way for tuning their structural properties. The acoustic and optical phonon shifts of the free-standing circular, hexagonal, square, and triangular SiNWs are calculated using a modified valence force field (MVFF) model. The acoustic phonon blue shift (acoustic hardening) and the optical phonon red shift (optical softening) show a strong dependence on the cross-section shape and size of the SiNWs. The triangular SiNWs have the least structural symmetry as revealed by the splitting of the degenerate flexural phonon modes and these show the minimum acoustic hardening and the maximum optical hardening. The acoustic hardening, in all SiNWs, is attributed to the decreasing difference in the vibrational energy distribution between the inner and the surface atoms with decreasing cross-section size. The optical softening is attributed to the reduced phonon group velocity and the localization of the vibrational energy density on the inner atoms. While the acoustic phonon shift shows a strong wire orientation dependence, the optical phonon softening is independent of wire orientation.
On a generalization of Jacobi's elliptic functions and the double sine-Gordon kink chain
Authors: Pawellek Michael
Published: November 2011

A generalization of Jacobi's elliptic functions is introduced as inversions of hyperelliptic integrals. We discuss the special properties of these functions, present addition theorems, and give a list of indefinite integrals. As a physical application, we show that periodic kink solutions (kink chains) of the double sine-Gordon model can be described in a canonical form in terms of generalized Jacobi functions.
On the Hurwitz zeta function of imaginary second argument
Authors: Fucci Guglielmo
Published: November 2011

In this work, we exploit Jonquière's formula relating the Hurwitz zeta function to a linear combination of polylogarithmic functions in order to evaluate the real and imaginary part of ζH(s, ia) and its first derivative with respect to the first argument s. In particular, we obtain expressions for the real and imaginary party of ζH(s, ia) and its derivative for s = m with \documentclass[12pt]{minimal}\begin{document}$m\in \mathbb {Z}\backslash \lbrace 1\rbrace$\end{document}m∈Z∖{1} involving simpler transcendental functions. We apply these results to the computation of the imaginary part of the one-loop effective action for massive scalar fields under the influence of a strong electric field in higher dimensional Minkowski spacetime.
Scanning photoelectron microscope for nanoscale three-dimensional spatial-resolved electron spectroscopy for chemical analysis
Authors: Horiba K. , Nakamura Y. , Nagamura N. , Toyoda S. , Kumigashira H. , Oshima M. , Amemiya K. , Senba Y. , Ohashi H.
Published: November 2011

In order to achieve nondestructive observation of the three-dimensional spatially resolved electronic structure of solids, we have developed a scanning photoelectron microscope system with the capability of depth profiling in electron spectroscopy for chemical analysis (ESCA). We call this system 3D nano-ESCA. For focusing the x-ray, a Fresnel zone plate with a diameter of 200 μm and an outermost zone width of 35 nm is used. In order to obtain the angular dependence of the photoelectron spectra for the depth-profile analysis without rotating the sample, we adopted a modified VG Scienta R3000 analyzer with an acceptance angle of 60° as a high-resolution angle-resolved electron spectrometer. The system has been installed at the University-of-Tokyo Materials Science Outstation beamline, BL07LSU, at SPring-8. From the results of the line-scan profiles of the poly-Si/high-k gate patterns, we achieved a total spatial resolution better than 70 nm. The capability of our system for pinpoint depth-profile analysis and high-resolution chemical state analysis is demonstrated.
Binary jumps in continuum. II. Non-equilibrium process and a Vlasov-type scaling limit
Authors: Finkelshtein Dmitri , Kondratiev Yuri , Kutoviy Oleksandr , Lytvynov Eugene
Published: November 2011

Let Γ denote the space of all locally finite subsets (configurations) in \documentclass[12pt]{minimal}\begin{document}$\mathbb {R}^d$\end{document}Rd. A stochastic dynamics of binary jumps in continuum is a Markov process on Γ in which pairs of particles simultaneously hop over \documentclass[12pt]{minimal}\begin{document}$\mathbb {R}^d$\end{document}Rd. We discuss a non-equilibrium dynamics of binary jumps. We prove the existence of an evolution of correlation functions on a finite time interval. We also show that a Vlasov-type mesoscopic scaling for such a dynamics leads to a generalized Boltzmann nonlinear equation for the particle density.
Geometric spectral inversion for singular potentials
Authors: Hall Richard L. , Lucha Wolfgang
Published: November 2011

The function E = F(v) expresses the dependence of a discrete eigenvalue E of the Schrödinger Hamiltonian H = −Δ + vf(r) on the coupling parameter v. We use envelope theory to generate a functional sequence {f [k](r)} to reconstruct f(r) from F(v) starting from a seed potential f [0](r). In the power-law or log cases, the inversion can be effected analytically and is complete in just two steps. In other cases, convergence is observed numerically. To provide concrete illustrations of the inversion method it is first applied to the Hulthén potential, and it is then used to invert spectral data generated by singular potentials with shapes of the form f(r) = −a/r + b sgn(q)rq and f(r) = −a/r + bln (r), a, b > 0. For the class of attractive central potentials with shapes f(r) = g(r)/r, with g(0) < 0 and g′(r) ⩾ 0, we prove that the ground-state energy curve F(v) determines f(r) uniquely.
High-temperature materials testing with full-field strain measurement: Experimental design and practice
Authors: Novak Mark D. , Zok Frank W.
Published: November 2011

Experimental characterization of the thermomechanical response of ceramic composites at very high temperatures is plagued by challenges associated with imaging and strain measurement. The problems involve illumination, heat haze, and surface contrast. Techniques that address these challenges have been developed and implemented in a laser heating facility, enabling non-contact strain measurement via digital image correlation. The thermomechanical characterization of both a Ni-based superalloy and a C/SiC composite are used to demonstrate the efficacy of experimental practices in realizing such measurements at temperatures up to 1500 °C.
A comparative study of the electrical properties of Pd/ZnO Schottky contacts fabricated using electron beam deposition and resistive/thermal evaporation techniques
Authors: Mtangi W. , Auret F. D. , Janse van Rensburg P. J. , Coelho S. M. M. , Legodi M. J. , Nel J. M. , Meyer W. E. , Chawanda A.
Published: November 2011

A systematic investigation to check the quality of Pd Schottky contacts deposited on ZnO has been performed on electron beam (e-beam) deposited and resistively/thermally evaporated samples using current-voltage, IV, and conventional deep level transient spectroscopy (DLTS) measurements. Room temperature IV measurements reveal the dominance of pure thermionic emission on the resistively evaporated contacts, while the e-beam deposited contacts show the dominance of generation recombination at low voltages, <0.30 V, and the dominance of pure thermionic emission at high voltages, greater than 0.30 V. The resistively evaporated contacts have very low reverse currents of the order of 10−10 A at a reverse voltage of 1.0 V whereas the e-beam deposited contacts have reverse currents of the order of 10−6 A at 1.0 V. Average ideality factors have been determined as (1.43 ± 0.01) and (1.66 ± 0.02) for the resistively evaporated contacts and e-beam deposited contacts, respectively. The IV barrier heights have been calculated as (0.721 ± 0.002) eV and (0.624 ± 0.005) eV for the resistively evaporated and e-beam deposited contacts, respectively. Conventional DLTS measurements reveal the presence of three prominent defects in both the resistive and e-beam contacts. Two extra peaks with energy levels of 0.60 and 0.81 eV below the conduction band minimum have been observed in the e-beam deposited contacts. These have been explained as contributing to the generation recombination current that dominates at low voltages and high leakage currents. Based on the reverse current at 1.0 V, the degree of rectification, the dominant current transport mechanism and the observed defects, we conclude that the resistive evaporation technique yields better quality Schottky contacts for use in solar cells and ultraviolet detectors compared to the e-beam deposition technique. The 0.60 eV has been identified as possibly related to the unoccupied level for the doubly charged oxygen vacancy, Vo2+.
Study of the local field distribution on a single-molecule magnet by a single paramagnetic crystal: A DPPH crystal on the surface of an Mn12-acetate crystal
Authors: Žilić Dijana , Rakvin Boris , Dalal Naresh S.
Published: November 2011

The local magnetic field distribution on the surface of a single-molecule magnet crystal (SMM) above blocking temperature (T≫Tb) detected for a very short time interval (~10-10s), has been investigated. Electron paramagnetic resonance (EPR) spectroscopy, using a local paramagnetic probe, was employed as a simple alternative detection method. An SMM crystal of [Mn12O12(CH3COO)16(H2O)4]·2CH3COOH·4H2O (Mn12-acetate) and a crystal of 2,2-diphenyl-1-picrylhydrazyl (DPPH), as the paramagnetic probe, were chosen for this study. The EPR spectra of DPPH deposited on Mn12-acetate show additional broadening and shifting in the magnetic field in comparison to the spectra of the DPPH in the absence of the SMM crystal. The additional broadening of the DPPH linewidth was considered in terms of the two dominant electron spin interactions (dipolar and exchange) and the local magnetic field distribution on the crystal surface. The temperature dependence of the linewidth of the Gaussian distribution of local fields at the SMM surface was extrapolated for the low-temperature interval (70–5 K).
The giant electrocaloric effect and high effective cooling power near room temperature for BaTiO3 thick film
Authors: Bai Yang , Zheng Guang-Ping , Ding Kai , Qiao Lijie , Shi San-Qiang , Guo Dong
Published: November 2011

The electrocaloric effect (ECE) of BaTiO3 multilayer thick film was investigated by direct calorimetric measurement. The ECE increases monotonically with the enhancement of applied field. The maximum ECE occurs above Tc and shifts to higher temperature with increasing applied field. Under an ultrahigh field of 800 kV/cm, it exhibits a giant ECE of ΔT = 7.1 K and ΔS = 10.1 J/kg · K at 80 °C. The ECE heat follows a general power-law relation with the varying rate of applied field within a certain range. A high cooling power (∼50 W/kg) is achieved based on the net-cooling resulting from the different varying rates of rising and falling fields.
Wide range tuning of external cavity bent-waveguide laser diode
Authors: Dybala Filip , Bajda Monika , Bercha Artem , Mrozowicz Milan , Trzeciakowski Witold , Ivonyak Yurii
Published: November 2011

Bent-waveguide laser emitting around 1550 nm was tuned by external grating (in Littrow configuration) at temperatures from 300 K down to 80 K and at hydrostatic pressures up to 2.2 GPa. The tuning range achieved with grating was significantly reduced at lower temperatures. The tuning range achieved by pressure and grating was 390 nm (from 1220 to 1610 nm). In this range the emission power of the laser was above 30 mW with narrow emission line and the side-mode suppression ratio above 30 dB. Our results were interpreted by calculating the pressure and temperature dependence of gain spectra determined from a nonparabolic 8×8 kp model.
Localized surface plasmon-enhanced electroluminescence from ZnO-based heterojunction light-emitting diodes
Authors: Zhang S. G. , Zhang X. W. , Yin Z. G. , Wang J. X. , Dong J. J. , Gao H. L. , Si F. T. , Sun S. S. , Tao Y.
Published: November 2011

We demonstrate the surface plasmon (SP) enhanced n-ZnO/AlN/p-GaN light-emitting diodes (LEDs) by inserting the Ag nanoparticles (NPs) between the ZnO and AlN layers. The ultraviolet/violet near band edge emission of the device is significantly enhanced while the green defect-related emission is modestly suppressed compared to the LEDs without Ag NPs. The red-shift of electroluminescence (EL) peak and the reduced photoluminescence decay lifetime of ZnO suggest that the improved EL performance of the device with Ag NPs is attributed to the resonant coupling between excitons in ZnO and localized SPs in Ag NPs.
InGaN epilayer characterization by microfocused x-ray reciprocal space mapping
Authors: Kachkanov V. , Dolbnya I. P. , O’Donnell K. P. , Martin R. W. , Edwards P. R. , Pereira S.
Published: November 2011

We report the use of microfocused three-dimensional x-ray reciprocal space mapping to study InGaN epilayers with average InN content ∼20%-22%. Analysis of the full volume of reciprocal space, while probing samples on the microscale with a focused x-ray beam, allowed us to gain valuable information about the nanostructure of InN-rich InGaN epilayers. It is found that “seed” InGaN mosaic nanocrystallites are twisted with respect to the ensemble average and strain-free. The initial stages of InGaN-on-GaN epitaxial growth, therefore, conform to the Volmer-Weber growth mechanism with “seeds” nucleated on strain fields generated by the a-type edge dislocations.
Polarity replication across m-plane GaN/ZnO interfaces
Authors: Kobayashi Atsushi , Ohnishi Tsuyoshi , Lippmaa Mikk , Oda Yasuhiro , Ishii Akira , Ohta Jitsuo , Oshima Masaharu , Fujioka Hiroshi
Published: November 2011

We have investigated the crystal plane alignment at m-plane GaN/ZnO heterointerfaces prepared by a room temperature epitaxial growth technique. Coaxial impact-collision ion scattering spectroscopy was used to show that the +c directions for GaN and ZnO are aligned at the GaN/ZnO (11¯00) hetero interface, which makes a striking contrast to polar c-plane GaN (0001)/ZnO (0001¯) interfaces, where polarity-flipping always occurs. Theoretical calculations revealed that an atomic alignment at the m-plane GaN/ZnO interface that maintains the +c direction across the interface is energetically favorable, although there could be an in-plane shift in the positions of the anions and cations at the interface.
Pd/InAlN Schottky diode with low reverse current by sulfide treatment
Authors: Chen Z. T. , Fujita K. , Egawa T.
Published: November 2011

The authors report the effect of sulfide treatment on electrical characteristic of Pd/InAlN Schottky diode. Quantitative analysis considering different current-transport mechanisms revealed that the sulfide treatment not only significantly reduced leakage current but also almost completely suppressed a tunneling current between InAlN surface and Pd contact, which could be attributed to the surface passivation of InAlN with forming S-N and S-O bonds as revealed by x-ray photoelectron spectroscopy (XPS) measurements. As a result of the treatment, the reverse-biased current was reduced significantly by more than one order of magnitude at −5 V to be as low as 3.95 × 10−8 A/cm2, and by more than two orders of magnitude at −10 V to be 1.27 × 10−7 A/cm2, corresponding to the record-low values reported to date.