bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evaluation of thin‐film solar cell temperature coefficients for space applications
Authors: Liu Simon H. , Simburger Edward J. , Matsumoto James , Garcia Alexander , Ross Jasen , Nocerino John 
Published: February 2005

AbstractAt present, commercially available thin‐film photovoltaic cells are evaluated for terrestrial applications. To apply thin‐film photovoltaic cells for space applications, the assessment of the solar cell performance must be conducted in simulated space conditions. We investigated the temperature coefficients of theI–Vcharacteristics of thin‐film amorphous silicon (a‐Si) solar cells manufactured by Uni‐Solar and Iowa Thin Film Technologies, and CuInGaSe2(CIGS) solar cells manufactured by MicroSat Systems with simulated space solar radiation. The temperature coefficient of the thin‐film solar cells between temperatures of 15 and 100°C was measured with a temperature‐controlled vacuum plate. The vacuum plate ensures maximum thermal contact between the plate and the solar cell as well as reducing the thermal gradient in the solar cell. The vacuum plate also serves as a thermal reservoir that provides temperature stability during the performance evaluation when the solar cell is exposed to simulated sunlight radiation. An X‐25 sunlight simulator calibrated for AM0 conditions provides the necessary radiation in performance characterization of the thin‐film solar cell. TheI–Vcharacteristics of the solar cell were obtained at various temperatures to gain a thorough knowledge of the cell's performance at different temperatures. Copyright © 2005 John Wiley & Sons, Ltd.
Teaching addition and subtraction to first graders: A Chinese perspective
Authors: Zhou Zheng , Peverly Stephen T. 
Published: February 2005

AbstractCross‐cultural studies on mathematical cognition and education have suggested that curriculum and teaching have contributed to U.S. versus Asian differences in student performance; however, previous discussions of curriculum and teaching practices have been very general and have not focused on a detailed analysis of how mathematics concepts are taught and presented in textbooks. To address this limitation, this article focuses on the teaching of addition and subtraction to first‐grade students in China. We discuss how curriculum topics are arranged, how concrete and abstract mathematical knowledge are reconciled in learning these concepts, and how teachers facilitate children's conceptual understanding of the logic behind addition and subtraction procedures. Toward this end, we analyze a research‐based Chinese mathematics curriculum to highlight the sequencing of topics pertaining to addition and subtraction and the instructional practices used by teachers to help students develop an understanding of these concepts. The purpose of this article is not to suggest that other nations' curriculum and instructional practices ought to follow the Chinese model. Rather, we attempt to provide useful information about developing effective curriculum and instructional practices that could help young children make sense of the mathematics they learn in school. © 2005 Wiley Periodicals, Inc. Psychol Schs 42: 259–272, 2005.
Autism in China: From acupuncture to applied behavior analysis
Authors: Clark Elaine , Zhou Zheng 
Published: February 2005

AbstractIt has been only in the past decade that autism has been widely recognized among Chinese service providers. As a result, there are few professionals who are trained to treat the disorder. Although efforts are currently under way to determine the prevalence of autism in China, to date there are no reliable data that indicate the magnitude of the problem. There are no formalized education programs for children with autism and only a handful of treatment programs in larger city hospitals and private schools. Treatments range from herbal medicines and acupuncture to sensory integration training and, in rare instances, applied behavior analysis (ABA). This article provides an update on what is taking place in China for autism treatment, and the challenges that lie ahead as the Chinese Ministry of Education struggles to address the needs of children identified with the disorder. © 2005 Wiley Periodicals, Inc. Psychol Schs 42: 285–295, 2005.
The measurement of stressful events in Chinese college students
Authors: Li Hong , Lin Chong‐De , Bray Melissa A. , Kehle Thomas J. 
Published: February 2005

AbstractThe Chinese College Stress Scale was developed to ascertain stress in university students. Results suggested that the psychometric properties of the Chinese College Stress Scale were satisfactory. Overall, student stress was primarily related to academic, personal, and negative life events. Approximately 8% of Chinese students exhibited high stress associated with attending the university whereas 74% exhibited low stress, and approximately 18% did not report any stress. The general pattern of stressful college events is similar to that found in American studies; however, the rank order of stressors is somewhat different between these findings and the results of American studies. The top academic stressors for Chinese university students were low learning efficiency and competition among students whereas the top academic stressors for American students were related to examinations. Personal hassles for the Chinese students involved concerns that they were not being taught or educated properly and inadequate social skills. In contrast, the major personal stressors of American students were found to be associated with intimate relationships and parental conflicts. © 2005 Wiley Periodicals, Inc. Psychol Schs 42: 315–323, 2005.
Properties of integral membrane protein structures: Derivation of an implicit membrane potential
Authors: Ulmschneider Martin B. , Sansom Mark S.P. , Di Nola Alfredo 
Published: February 2005

AbstractDistributions of each amino acid in the trans‐membrane domain were calculated as a function of the membrane normal using all currently available α‐helical membrane protein structures with resolutions better than 4 Å. The results were compared with previous sequence‐ and structure‐based analyses. Calculation of the average hydrophobicity along the membrane normal demonstrated that the protein surface in the membrane domain is in fact much more hydrophobic than the protein core. While hydrophobic residues dominate the membrane domain, the interfacial regions of membrane proteins were found to be abundant in the small residues glycine, alanine, and serine, consistent with previous studies on membrane protein packing. Charged residues displayed nonsymmetric distributions with a preference for the intracellular interface. This effect was more prominent for Arg and Lys resulting in a direct confirmation of the positive inside rule. Potentials of mean force along the membrane normal were derived for each amino acid by fitting Gaussian functions to the residue distributions. The individual potentials agree well with experimental and theoretical considerations. The resulting implicit membrane potential was tested on various membrane proteins as well as single trans‐membrane α‐helices. All membrane proteins were found to be at an energy minimum when correctly inserted into the membrane. For α‐helices both interfacial (i.e. surface bound) and inserted configurations were found to correspond to energy minima. The results demonstrate that the use of trans‐membrane amino acid distributions to derive an implicit membrane representation yields meaningful residue potentials. Proteins 2005. © 2005 Wiley‐Liss, Inc.
A multibody, whole‐residue potential for protein structures, with testing by Monte Carlo simulated annealing
Authors: Mayewski Stefan 
Published: February 2005

AbstractA new multibody, whole‐residue potential for protein tertiary structure is described. The potential is based on the local environment surrounding each main‐chain α carbon (CA), defined as the set of all residues whose CA coordinates lie within a spherical volume of set radius in 3‐dimensional (3D) space surrounding that position. It is shown that the relative positions of the CAs in these local environments belong to a set of preferred templates. The templates are derived by cluster analysis of the presently available database of over 3000 protein chains (750,000 residues) having not more than 30% sequence similarity. For each template is derived also a set of residue propensities for each topological position in the template. Using lookup tables of these derived templates, it is then possible to calculate an energy for any conformation of a given protein sequence. The application of the potential to ab initio protein tertiary structure prediction is evaluated by performing Monte Carlo simulated annealing on test protein sequences. Proteins 2005. © 2005 Wiley‐Liss, Inc.
Neural network‐based prediction of mutation‐induced protein stability changes in Staphylococcal nuclease at 20 residue positions
Authors: Frenz Christopher M. 
Published: February 2005

AbstractProtein‐based therapeutics are playing an increasingly important role in the treatment of diseases, including diabetes and cancer. The viability of these treatments, however, are highly dependent on the stability of the therapeutic, since stability affects both the shelf life of the therapeutic as well as its active life in the body. Stability engineering can, therefore, be used to increase the effectiveness of protein‐based therapeutics. Computational methods of protein stability prediction have been under development for about a decade, but complex molecular interactions make stability prediction difficult and computationally intensive. A rapid computational method of protein stability prediction is developed using feed‐forward neural networks and used to predict mutation‐induced stability changes in Staphylococcal nuclease. The input to the neural network consisted of sequences of evolutionarily based amino acid similarity scores that were obtained through the comparison of the amino acids in a mutation containing sequence to their positional counterparts in the baseline wild‐type amino acid sequence. A training set was created which consisted of similarity score sequences, for which the stabilities of the corresponding amino acid sequences were known, paired with the relative stabilities of the sequences to that of the baseline. Back‐propagation of error was used to train the network to output accurate relative stability scores for the sequences in the training set. Neural network‐based relative stability predictions for 55 sequences containing mutation combinations not found in the training set had an accuracy of 92.8%. Proteins 2005. © 2005 Wiley‐Liss, Inc.
Characterization of differently grown GaN epilayers by time‐resolved four‐wave mixing technique
Authors: Jarašiūnas K. , Malinauskas T. , Aleksiejūnas R. , Sūdžius M. , Frayssinet E. , Beaumont B. , Faurie J.‐P. , Gibart P. 
Published: February 2005

AbstractRoom temperature time‐resolved four‐wave mixing has been performed in MOCVD GaN epilayers, grown on sapphire substrates by using either conventional or a 3D‐growth mode with Si/N treatment technique (micro‐ELO). Picosecond pulses at 355 nm were used to create light interference pattern and record a spatially modulated carrier distribution by interband transitions, while a delayed probe beam at 1064 nm monitored the carrier dynamics far from the bandgap. The determined values of the bipolar diffusion coefficient and the carrier lifetime were found equal to Da = 1.7–1.8 cm2/s and τR ≈ 1.1 ns for standard grown epilayers, while in the samples with ultralow dislocation density they were found equal to 2.4 cm2/s and 2.7 ns. In the interface region of the epilayers with high dislocation density, a dependence of D and τR values on excitation intensity was found. The latter effect was attributed to a screening of potencial barriers around the charged dislocations by free carriers and an ability of the carriers to become less localized and thus avoid the nonradiative recombination at dislocations. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Free energy and capture cross section of the E2 trap in n‐type GaN
Authors: Pernot J. , Ulzhöfer C. , Muret P. , Beaumont B. , Gibart P. 
Published: February 2005

AbstractFree energy and capture cross section of the E2 trap in n‐type GaN are investigated by deep level transient spectroscopy with the help of an experimental method, relying on space charge depth modulation [D. Pons, J. Appl. Phys. 55, 3644 (1984)]. This technique is applied with a large range of filling pulse durations (up to 6 orders of magnitude) and for temperature varying between 260 K and 330 K. Entropy and capture barrier are found to be negligible. Analysis of our results makes N in Ga site (NGa antisite) as the best candidate for this trap. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Defect tuning of GaAs doping superlattices by hydrogen ion implantation
Authors: Brink D. J. , Haile K. M. , Kunert H. W. 
Published: February 2005

AbstractGaAs doping superlattices were implanted with 0.5 MeV hydrogen ions at doses ranging from 1012 to 1016 cm–2. This gradually modified their optical characteristics from superlattice behaviour to something resembling the bulk material and beyond. Ellipsometry and near infrared reflectance measurements were used to determine the dose dependent effective band gap. Implantation damage could be reversed to a large extent by a simple thermal annealing step. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Terahertz generation by plasma waves in nanometer gate high electron mobility transistors
Authors: Łusakowski J. , Teppe F. , Dyakonova N. , Meziani Y. M. , Knap W. , Parenty T. , Bollaert S. , Cappy A. , Popov V. , Shur M. S. 
Published: February 2005

AbstractA resonant voltage tuneable radiation (0.4 THz–1.0 THz) from the gated two dimensional electron gas in a 60 nm InGaAs field effect transistor was investigated. We show that (i) the observed emission appears once the drain‐to‐source voltage, UDS, exceeds the threshold value, UTH; (ii) the resonant frequency can be tuned by UDS in agreement with the current driven plasma instability model of Dyakonov and Shur; (iii) by applying a quantizing magnetic field one increases UTH linearly with the magnetic field while the evolution of the emission signal is approximately a universal function of (UDS–UTH). (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Barrier inhomogeneities and electrical characteristics of Ni/Ti bilayer Schottky contacts on 4H–SiC after high temperature treatments
Authors: Pérez R. , Mestres N. , Montserrat J. , Tournier D. , Godignon P. 
Published: February 2005

AbstractThe analysis of “nonideal” behaviour in current–voltage characteristics of fabricated Schottky diodes on 4H–SiC is carried out. An accurate theoretical modelling of the effect of the presence of inhomogeneities on the electron transport across the metal‐semiconductor interface is applied. This model trends to explain a large series of abnormal experimental results obtained on “real” Schottky diodes. Our results clearly demonstrate that the electron transport at the metal–semiconductor interface is significantly affected by low barrier regions. It is suggested that the commonly observed larger‐than‐unity ideality factors, underestimation of the Richardson constant and Schottky Barrier Height correlation with ideality factor can be attributed to an effective area involved in the current transport which may be significantly lower than the geometric area of the diode contact. It is also proved by comparing different types of Schottky diodes that in order to properly characterise the interface uniformity, not only the absolute value of the ideality factor is important but also its temperature dependence and its correlation with barrier height have to be taken into account. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Manifestation of the equilibrium hole distribution in photoluminescence of n‐InN
Authors: Klochikhin A. A. , Davydov V. Yu. , Emtsev V. V. , Sakharov A. V. , Kapitonov V. A. , Andreev B. A. , Lu Hai , Schaff William J. 
Published: February 2005

AbstractPhotoluminescence (PL) of n‐InN grown by molecular beam epitaxy with Hall concentrations from 3.6 to 7.3 × 1017 cm–3 demonstrates dependences on carrier concentration, temperature, and excitation density which give evidences of a fast energy relaxation rate of photoholes and their equilibrium distribution over localized states. The structure of the PL spectra observed at 4.2 and 77 K in the energy interval from 0.50 to 0.67 eV indicates that a considerable part of holes is trapped by deep and shallow acceptors before the interband recombi‐ nation with degenerate electrons occurs. At room temperature, the band‐to‐band recombination of free holes and electrons dominates in PL. Experimental results on PL and absorption are described by model calculations under the assumptions of a band gap equal to 0.665–0.670 eV at zero temperature and zero carrier concentration and a non‐parabolic conduction band with the effective mass at the G‐point equal to 0.07 of the free electron mass. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Liquid chromatography/mass spectrometry analysis of bifunctional electrophiles and DNA adducts from vitamin C mediated decomposition of 15‐hydroperoxyeicosatetraenoic acid
Authors: Williams Michelle V. , Lee Seon Hwa , Blair Ian A. 
Published: February 2005

AbstractReactive oxygen species convert the ω‐6 polyunsaturated fatty acid arachidonic acid into 15‐hydroperoxy‐5,8,11,13‐(Z,Z,ZE)‐eicosatetraenoic acid (15‐HPETE). Cyclooxygenases and lipoxygenases can also convert arachidonic acid into 15‐HPETE. Vitamin C mediated decomposition of 15(S)‐HPETE to protein‐ and DNA‐reactive bifunctional electrophiles was examined by normal‐phase liquid chromatography/atmospheric pressure chemical ionization/mass spectrometry (LC/APCI‐MS). The individual bifunctional electrophiles, trans‐4,5‐epoxy‐2(E)‐decenal (t‐EDE), cis‐4,5‐epoxy‐2(E)‐decenal (c‐EDE), 4‐oxo‐2(E)‐nonenal (ONE), and 4‐hydroxy‐2(E)‐nonenal (HNE), exhibited protonated molecules at m/z 169, 169, 155, and 157, respectively. The MH+ ion at m/z 173 for 4‐hydroperoxy‐2(E)‐nonenal (HPNE) was very weak with an ion corresponding to the loss of OH at m/z 156 as the major ion in the APCI mass spectrum. The bifunctional electrophiles were all separated under normal‐phase LC conditions. All five bifunctional electrophiles were formed when 15‐HPETE was treated with vitamin C. The LC/MS‐based methodology showed that t‐EDE was the major bifunctional electrophile formed during vitamin C mediated 15(S)‐HPETE decomposition. Stable isotope dilution LC/MS studies revealed that this did not result in the formation of increased levels of unsubstituted etheno‐dGuo adducts in calf thymus DNA when compared with 13(S)‐hydroperoxy‐9,10‐(Z,E)‐octadecadienoic acid [13(S)‐HPODE], a lipid hydroperoxide derived from linoleic acid. However, the formation of heptanone‐etheno‐dGuo adducts in calf thymus DNA was reduced when compared with the 13(S)‐HPODE. This was attributed to the reduced formation of ONE from 15‐HPETE when compared with its formation from 13‐HPODE. In contrast to reactions with dGuo or DNA conducted using 13(S)‐HPODE, no carboxy‐containing adducts were observed with 15(S)‐HPETE. Copyright © 2005 John Wiley & Sons, Ltd.
An accurate semi‐empirical equation for sputtering yields I: for argon ions
Authors: Seah M. P. , Clifford C. A. , Green F. M. , Gilmore I. S. 
Published: February 2005

AbstractAn analysis has been made of the historical data for argon ion sputtering yields of 28 mono‐elemental solids in the energy range 250–10 000 eV to develop an improved semi‐empirical formula based on Matsunami et al.'s and Yamamura and Tawara's formulations. The best result is found if an essential component involving the target density is included in Matsunami et al.'s approach. The scatter between the predictions and the experimental data is reduced to 9.0% by generating an analytical expression for the term Q that requires none of the target‐specific numbers from special look‐up tables of the type used by Matsunami et al. and Yamamura and Tawara. For elements other than the 34 elements for which Q values are tabulated, the new Q values range up to a factor of 5 from the default value that they recommend.The predictions are tested by a new method for determining sputtering yields using atomic force microscopy to measure very small crater volumes sputtered in ultrahigh vacuum. Here, 26 mono‐elemental targets were studied using a 5 keV argon ion beam set at 45° to the surface normal. The effect of the angle of incidence is evaluated best using Yamamura et al.'s angular equations for this contribution. Results for Sb, Te and Bi indicate a significantly higher sputtering yield than expected. This is thought to arise from the high content of polyatomic groups associated with the low sublimation energies for such clusters in the pure elements of groups V‐B and VI‐B of the Periodic Table. These 5 keV sputtering yield data, excluding Sb, Te and Bi, fit the new equations with a scatter of 20%. Results using SRIM‐2003 exhibit a poorer scatter of 27%. © Crown Copyright 2005. Reproduced with the permission of Her Majesty's Stationary Office. Published by John Wiley & Sons, Ltd.
Myelopeptides: Bone marrow regulatory mediators
Authors: Petrov Rem V. , Mikhailova Augusta A. , Fonina Larissa A. 
Published: February 2005

Bone marrow cells of various animal species and men produce a group of bioregulatory peptides called myelopeptides (MPs). A highly purified MP fraction and some individual molecules have been isolated from the supernatant of porcine bone marrow cell cultures by reverse phase chromatography.MPs have a wide spectrum of functional activities: immunoregulatory, differentiating and opiate-like. They evoke 2–5-fold stimulation of antibody production to various antigens. They correct some immune defects in MRL/lpr mice with spontaneous autoimmune disorders that results in 2-fold prolongation of the life span of these mice. MPs influence the differentiation of bone marrow and peripheral blood cells derived from healthy and leukemic donors. They induce terminal differentiation in the leukemic human HL-60 cell line. MPs also show an effect on pain sensitivity.A new immunocorrective drug Myelopid has been developed on the basis of MP mixtures. This drug is effectively used in Russia both in medicine and veterinary practice for prophylaxis and treatment of diseases accompanied by immunodeficiency.Two individual MPs were isolated and identified: Phe-Leu-Gly-Phe-Pro-Thr (MP-1) and Leu-Val-Val-Tyr-Pro-Trp (MP-2). MP-1 displays immunoregulatory activity; MP-2 abolishes the inhibitory effect of leukemic cells on T-lymphocyte functional activity.MPs seem to provide not only immunoregulation but also to participate in complex interactions between different systems in the organism.
Transformations of normal and inverted function tables
Authors: Zucker J. I. 
Published: February 2005

AbstractWe develop a theory of function tables, similar to, and inspired by, that given in the work of D. Parnas. We consider, in particular, two classes of function tables: normal and inverted. We study effective transformations between tables of these two classes, as well as transformations which change the dimension of a table. We also consider the interrelationship between these three types of transformation.