bluuebunny/crossref_metadata_2025_split huggingface dataset:
Spinodal decomposition and the luminescence of Er in AlxIn1−xN:Er layers
Authors: Yang Miao , Weng Ye , Strunk Horst P. 
Published: November 2012

AbstractIntegrated photoluminescence intensities of the green lines from Er centers (2H11/2–4I15/2 and 4S3/2–4I15/2) embedded in AlxIn1−xN films are investigated in dependence of excitation energy and band gap energy of the film host. The films are deposited onto silicon and sapphire substrates by sputtering and subsequently annealed for optimization of the luminescence intensity. Two significant maxima of integrated intensity are observed. The first maximum appears, if the excitation energy matches the band gap energy of the AlxIn1−xN matrix. It can be explained by a bound exciton mediated energy transfer to Er centers. The second maximum occurs at below band gap energy excitation of some films with special compositions. These observations call for an adequate path for the excitation of Er. We propose a mechanism based on spinodal decomposition of AlxIn1−xN. In fact, our calculations and experiments (structure analysis in a transmission electron microscope) confirm that nanoparticles form of an In‐rich AlxIn1−xN phase, which can be assumed as quantum dots. Resonant energy transfer from these quantum dots into the luminescent centers can explain the Er luminescence enhancement.
Anisotropy of porous silicon formation rate in p‐Si
Authors: Astrova E. V. , Zharova Yu. A. , Ulin V. P. , Enicheva G. V. 
Published: November 2012

AbstractWe studied the anisotropy of meso‐ and microporous silicon formation rate on curved surfaces and on flat samples. Experiments on anodization of model p++‐cylinders demonstrated that faceting appears on their lateral surface. This indicates that the etching rates vary between different crystallographic planes. Quantitative data on the etching‐rate anisotropy were obtained by anodization of wafers through a mask in the form of narrow wedges radiating from a center in all directions (wagon wheel mask). We examined the dependence of porous silicon formation rate anisotropy on current and Si doping. It was shown that for p++ substrates, in all anodization modes, the <100> direction corresponds to the maximum growth rate. The current affects the etching‐rate distribution among crystallographic directions: under low currents anisotropy of pore‐front propagation rate may be as high as 20%. An even stronger influence on the anisotropy characteristics is exerted by the substrate doping level. It was found for the first time that, for silicon with acceptor concentration NB ≈ 1017–1018 cm−3, the <111> axis becomes the fastest growth direction, and the <100> axis, by contrast, is transformed to the direction of the slowest pore‐front propagation. This phenomenon correlates with rotation of the optical axis in birefringent mesoporous silicon on passing from p++‐Si to p+‐Si, as is known from the literature.
Surface passivation for ultrathin Al2O3 layers grown at low temperature by thermal atomic layer deposition
Authors: Frascaroli J. , Seguini G. , Cianci E. , Saynova D. , van Roosmalen J. , Perego M. 
Published: November 2012

AbstractThin layers of Al2O3 with thickness tox ≤ 8 nm were grown by thermal atomic layer deposition at low temperature of 100 °C and applied to achieve functional surface passivation of crystalline silicon substrates. Measurements of the effective lifetime were performed to characterize the surface passivation effect. Lifetime values in the range of 0.5 ms were obtained for Al2O3 films with tox ≥ 6 nm upon post‐deposition annealing (PDA) at 250 °C in N2 atmosphere. However, when the thickness of the Al2O3 films was reduced to 4 nm, lifetime values well below 0.1 ms were observed even after PDA. Combined capacitance–voltage and conductance–voltage measurements were carried out to extract the amount of charges located near the silicon‐oxide interface and the density of electrically active interface states, respectively. The results of the electrical characterization were used to elucidate the intimate physical mechanisms that govern charge recombination at the Al2O3/Si interface.Density of interface states (a) and lifetime (b) values are reported as a function of the PDA temperature for Al2O3 films of three different thickness values: 4, 6, and 8 nm. magnified image
Crystalline graphite oxide/PVDF nanocomposite gate dielectric: Low‐voltage and high field effect mobility thin‐film transistor
Authors: Sannigrahi J. , Bhadra D. , Chaudhuri B. K. 
Published: November 2012

AbstractWe fabricated an anthracene thin‐film transistor (TFT) with an ultrathin layer (∼450 nm) of poly‐vinylidene fluoride (PVDF)/graphite oxide nanoplatelets (GOnP) nanocomposite as a gate insulator. We obtained a TFT device with excellent electrical characteristics at low operating voltages (<1 V). The dielectric is a high‐ε gate insulator with a static dielectric constant of εr = 15.6. This device was found to have a field effect mobility of 1.1 cm2 V−1 s, a threshold voltage of 0.34 V, an exceptionally low subthreshold slope (SS) of 380 mV decade−1 and an on/off ratio of 105. The combination of favorable properties opens up the possibility to utilize such TFTs effectively at voltages as low as below 1 V. Such high‐ε PVDF/GOnP gate dielectric appears to be highly promising candidates for organic nonvolatile memories and sensor field effect transistors (FETs).
Elastic anisotropy and thermodynamic properties of tetrahedrally bonded dense C2N2(NH) under high pressure and high temperature
Authors: Yan Haiyan , Zhang Meiguang , Wei Qun , Guo Ping 
Published: November 2012

AbstractThe elastic anisotropy and thermodynamic properties of the potential superhard carbon nitride phase C2N2(NH) have been investigated by using an ab initio plane‐wave pseudopotential density theory method. The crystal parameters have been calculated at ambient as well as high pressure. The Young's modulus and shear modulus as a function of crystal orientations for C2N2(NH) have been systematically investigated. The Young's modulus is found to reach a maximum along the [100] direction. Using a set of total energy versus volume obtained with the first‐principles calculations, the quasiharmonic Debye model is applied to the study of the thermal and vibrational effects. The dependence of Debye temperature, Grüneisen parameter, heat capacity, and expansion coefficient on the temperature and pressure are systematically explored in the whole pressure range from 0 to 60 GPa and temperature range from 0 to 2000 K.
Neural network potentials for metals and oxides – First applications to copper clusters at zinc oxide
Authors: Artrith Nongnuch , Hiller Björn , Behler Jörg 
Published: November 2012

AbstractThe development of reliable interatomic potentials for large‐scale molecular dynamics (MD) simulations of chemical processes at surfaces and interfaces is a formidable challenge because a wide range of atomic environments and very different types of bonding can be present. In recent years interatomic potentials based on artificial neural networks (NNs) have emerged offering an unbiased approach to the construction of potential energy surfaces (PESs) for systems that are difficult to describe by conventional potentials. Here, we review the basic properties of NN potentials and describe their construction for materials like metals and oxides. The accuracy and efficiency are demonstrated using copper and zinc oxide as benchmark systems. First results for a potential of the combined ternary CuZnO system aiming at the description of oxide‐supported copper clusters are reported.magnified imageModel of a copper cluster at the ZnO($10\overline {1} 0$) surface.
Raman‐scattering probe of anharmonic effects due to temperature and composition in InGaN
Authors: Kong J. F. , Shen W. Z. , Guo Q. X. 
Published: November 2012

AbstractWe have carried out a detailed investigation of temperature‐dependent micro‐Raman scattering on In1 − xGaxN films with different Ga compositions (0.06 ≤ χ ≤ 0.91). The observed phonon frequency downshift and linewidth broadening with increasing temperature of A1(LO) and E2(high) modes can be well explained by a model taking into account the contributions of the thermal expansion, the lattice‐mismatch‐induced strain, and the anharmonic phonon processes. We have elucidated the variation with Ga composition of the contribution of the three‐ and four‐phonon processes in the anharmonic effect. It is found that with increasing Ga composition the three‐phonon process increases over the four‐phonon process. The variation in the relative contribution from three‐ and four‐processes can be further attributed to the diversification of structural properties and phonon density of states in InGaN.
Dislocations in 4H‐ and 3C‐SiC single crystals in the brittle regime
Authors: Demenet Jean‐Luc , Amer Madyan , Tromas Christophe , Eyidi Dominique , Rabier Jacques 
Published: November 2012

AbstractNanoindentations at room temperature have been performed on 4H‐ and 3C‐SiC single crystals, and resulting microstructures have been analyzed by Transmission Electron Microscopy. In both structures, dislocations emitted from imprints are perfect dislocations lying in the basal plane for 4H‐ and in the {111} planes for 3C‐SiC. Dislocation segments are not dissociated and they are assumed to be lying in the shuffle set where only one bound per atom has to be cut for dislocation motion. It is deduced that the low stacking fault energy of silicon carbide is not involved in plasticity under high stress as compared to high temperature behaviour. The change in deformation mechanism reported in this study indicates that silicon carbide exhibits the same behaviour under high stress as other semiconducting materials, as silicon or antimonide indium. This could be a general feature for all this family of materials (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modification of dislocation PL centres due to misfit of bonded Si wafers
Authors: Steinman E. , Tereshchenko A. , Kononchuk O. , Vdovin V. 
Published: November 2012

AbstractStructure and low temperature photoluminescence of Si(001) hydrophilic bonded wafers have been studied. Even at minimal misfit angles the observed dislocation related luminescence (DL) did not coincide with the luminescence of isolated dislocations. The dependence of spectral distribution of DL on the dislocation network density has been studied and analyzed on the basic of previously suggested recombination model. A strong dependence of the spectral distribution of DL on the misfit angle has been found. The temperature dependence of different sub bands in DL spectra has been interpreted in the model of successive thermal emptying of upper states. The similar behavior of DL at increasing temperature and increasing density of misfit dislocations has been interpreted in the model of a relative dependence of dislocation related upper states on the distance between dislocations (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Energetic spectra of dislocation networks produced by hydrophilic bonding of silicon wafers
Authors: Kolevatov I. , Trushin M. , Vyvenko O. , Kittler M. , Kononchuk O. 
Published: November 2012

AbstractElectronic states of dislocation networks produced by Si wafers bonding was studied by means of deep level transient and admittance spectroscopy methods. A strong field‐enhanced hole thermoemission was established for one shallow and one deep states in p‐type Si that was explained in the framework of dislocation‐related Poole‐Frenkel‐effect model. The shallow dislocation related states situated close to the valence as well as to the conduction band of silicon were found to be associated with the broad energetic bands with rapid interstate exchange. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Degenerate random environments
Authors: Holmes Mark , Salisbury Thomas S. 
Published: November 2012

AbstractWe consider connectivity properties of certain i.i.d. random environments on, where at each location some steps may not be available. Site percolation and oriented percolation are examples of such environments. In these models, one of the quantities most often studied is the (random) set of vertices that can be reached from the origin by following a connected path. More generally, for the models we consider, multiple different types of connectivity are of interest, including: the set of vertices that can be reached from the origin; the set of vertices from which the origin can be reached; the intersection of the two. As with percolation models, many of the models we consider admit, or are expected to admit phase transitions. Among the main results of the paper is a proof of the existence of phase transitions for some two‐dimensional models that are non‐monotone in their underlying parameter, and an improved bound on the critical value for oriented site percolation on the triangular lattice. The connectivity of the random directed graphs provides a foundation for understanding the asymptotic properties of random walks in these random environments, which we study in a second paper. © 2012 Wiley Periodicals, Inc. Random Struct. Alg., 45, 111–137, 2014
Mobile user authentication system in cloud environment
Authors: Yeh Her‐Tyan , Chen Bing‐Chang , Wu Yi‐Cong 
Published: November 2012

ABSTRACTIn order to reach a safe environment that can be automatically used on the Internet and to take precautions against the Internet fishing attack, the system integrates some features including one‐time password, Completely Automated Public Turing Test to tell Computers and Humans Apart, voiceprint identification of creatural features, and visual cryptography, designing a formula wherein users do not need to remember any accounts and passwords when they surf the Internet through mobile devices, and it aims at smart phones and the Cloud. The formula is able to improve the problems of rampant Internet fishing and the management of passwords. In techniques, on one hand, it uses PIN information visual passwords in cell phones to improve the security of the account; on the other hand, it uses voiceprint identification features so that the system center can ensure the user's identification with a view to improve the leak in mobile devices rather than only to check mobile devices. And then, it utilizes the voiceprint, which we use when we log in, to produce a one‐time password that is able to lower the risk of the account and passwords being attacked by Internet fishing. Through the frame of this research, it can protect our cell phones from being lost and embezzled and can prevent the account and passwords from being attacked by Internet fishing. It can also solve the problem of users forgetting accounts and passwords, and reduce the operational burden of cell phones. Besides, it is capable of preventing the Cloud servers from incurring many malicious registrations and logins, keeping them working efficiently. Copyright © 2012 John Wiley & Sons, Ltd.
Preventive Cancer Stem Cell-Based Vaccination Reduces Liver Metastasis Development in a Rat Colon Carcinoma Syngeneic Model
Authors: Duarte Sonia , Momier David , Baqué Patrick , Casanova Vincent , Loubat Agnès , Samson Michel , Guigonis Jean-Marie , Staccini Pascal , Saint-Paul Marie-Christine , De Lima Maria Pedroso , Carle Georges F. , Pierrefite-Carle Valérie 
Published: November 2012

Abstract
Cancer stem cells (CSCs) represent a minor population of self-renewing cancer cells that fuel tumor growth. As CSCs are generally spared by conventional treatments, this population is likely to be responsible for relapses that are observed in most cancers. In this work, we analyzed the preventive efficiency of a CSC-based vaccine on the development of liver metastasis from colon cancer in a syngeneic rat model. We isolated a CSC-enriched population from the rat PROb colon carcinoma cell line on the basis of the expression of the aldehyde dehydrogenase-1 (ALDH1) marker. Comparative analysis of vaccines containing lysates of PROb or ALDHhigh cells by mass spectrometry identifies four proteins specifically expressed in the CSC subpopulation. The expression of two of them (heat shock protein 27-kDa and aldose reductase) is already known to be associated with treatment resistance and poor prognosis in colon cancer. Preventive intraperitoneal administration of vaccines was then performed before the intrahepatic injection of PROb cancer cells. While no significant difference in tumor occurrence was observed between control and PROb-vaccinated groups, 50% of the CSC-based vaccinated animals became resistant to tumor development. In addition, CSC-based vaccination induced a 99.5% reduction in tumor volume compared to the control group. To our knowledge, this study constitutes the first work analyzing the potential of a CSC-based vaccination to prevent liver metastasis development. Our data demonstrate that a CSC-based vaccine reduces efficiently both tumor volume and occurrence in a rat colon carcinoma syngeneic model.
The parallel operation control of a modular AC to DC converter via serial communication bus
Authors: Kanthaphayao Yutthana , Kamnarn Uthen , Chunkag Viboon 
Published: November 2012

AbstractThis paper presents the parallel operation control of a modular AC to DC converter via a serial communication bus. In the proposed system, multiple AC to DC converters are parallel‐connected at the output end for load current sharing. Each module of the AC to DC converter is controlled by its individual microcontroller. The microcontroller of each module is employed for the voltage control loop and communicates with the microcontrollers of the other converter modules. The RS485 serial communication is used to transmit information among the controllers, which checks the number of the converter module for calculating the input inductor current command of each converter module. Moreover, the clock signal is used for synchronization to prevent data collision on the serial communication bus. The proposed parallel operation control provides fast response when the converter module connects or disconnects according to the required power. The performance evaluation of the proposed system is conducted by simulation and experimental verification on two parallel isolated CUK converters. © 2012 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.
Smoke detection in open areas with texture analysis and support vector machines
Authors: Maruta Hidenori , Nakamura Akihiro , Kurokawa Fujio 
Published: November 2012

AbstractEarly and certain fire detection is one of the important issues to keep infrastructures safe. Especially, it becomes an urgent problem for open places such as port facilities, large factories, and power plants, due to its large harmful effect to the surrounding areas. In these places, direct detection of fire or flame has some difficulties because they are open and hence have problem to set sensor devices. Therefore, smoke is an important and useful sign to detect fire or flames robustly even in such cases. In this paper, we present a novel smoke detection method based on image information. First, we extract moving objects in an image sequence as smoke candidate regions in a preprocessing step. Since smoke has a characteristic pattern as image information, we focus on the texture pattern of smoke. Here, we use texture analysis to extract feature vectors of the images. To classify extracted areas of moving objects to smoke or nonsmoke, we use support vector machines (SVMs) with texture features as an input feature vector. Extraction of moving objects is sometimes easily and greatly affected by environmental conditions such as wind, background objects, and so forth. It obviously causes bad classification results. To solve this problem, we additionally accumulate the results of classification with SVM about time to obtain accurate extraction result of smoke regions under these conditions. Experimental results using real‐scene data show that our method works effectively under several different environmental conditions. © 2012 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.
Coarse‐grained models of protein folding as detailed tools to connect with experiments
Authors: Naganathan Athi N. 
Published: November 2012

AbstractProtein folding, a process that spans a wide range of timescales and that involves complex conformational dynamics, is an extremely challenging problem to decode at the atomic level. Over the past decade, coarse‐grained (CG) models that rely on a reduced representation of the polymer chain as dictated by the native structure have been quite successful in characterizing and predicting a variety of aspects of the folding mechanism of single‐domain proteins. The ever‐increasing ability of this minimalist treatment is a primarily due to the rapid and efficient sampling afforded by coarse‐graining that smoothens the folding landscape and the simple nature of the constituent physical energy functions that can be easily cast in various forms or parameterized using experimental or knowledge‐based approaches. With the advances in computational power we have now reached a stage where CG simulations can be routinely performed to test various mechanistic hypothesis, to interpret intricate experimental observables and even suggest new experimental avenues. Here, we provide an overview of recent CG developments that have predicted experiments quantitatively and others that have sought to use experimental information as constraints to tune the energetics and answer fundamental questions in folding and conformational behavior of proteins. We further discuss open issues and point to new directions that can drive the CG models toward better agreement with experiments and to a better understanding of folding mechanisms in general. © 2012 John Wiley & Sons, Ltd.This article is categorized under:

Electronic Structure Theory > Density Functional Theory
Mycotic Aneurysms in the Abdominal Aorta and Iliac Arteries: CT‐based Grading and Correlation with Surgical Outcomes
Authors: Lai Chao‐Han , Chang Ruey‐Sheng , Luo Chwan‐Yau , Kan Chung‐Dann , Lin Pao‐Yen , Yang Yu‐Jen 
Published: November 2012

AbstractBackgroundComputed tomography (CT) is the modality of choice in the diagnosis of mycotic aneurysms. The present study aimed to classify the CT findings of mycotic aneurysms, and to assess their predictive value based on the correlation of a CT‐based grading system with prognostic factors and outcomes.MethodsOver the past 21 years, 40 consecutive patients underwent open surgery for mycotic aneurysms of the abdominal aorta and iliac arteries in our hospital. The CT appearances of mycotic aneurysms were categorized into four grades: grade 1, periarterial changes without destruction of the arterial wall; grade 2, presence of saccular outpouching; grade 3, extensive retroperitoneal infection; and grade 4, massive perianeurysmal hemorrhage. Clinical data were recorded for analysis.ResultsThe surgical mortality and overall aneurysm‐related mortality rates were 17.5 and 25 %, respectively. The poor prognostic predictors were shock, rupture, and concomitant gastrointestinal procedures. The increasing proportions of shock and rupture status corresponded to mycotic aneurysms of higher grades in the CT‐based grading. In addition, one patient in grades 1 and 2, versus five in grades 3 and 4 (P = 0.02), required concomitant gastrointestinal procedures. The CT‐based grading exhibited a strong association with surgical mortality (Cramer’s V coefficient = 0.65; P = 0.002) and a relatively strong association with overall aneurysm‐related mortality (Cramer’s V coefficient = 0.53; P = 0.01).ConclusionsFor patients surgically treated for abdominal mycotic aneurysms, the CT‐based grading is correlated with clinical severity, surgical complexity, and outcomes, and thus it may serve as a simple scale for risk classification.