bluuebunny/crossref_metadata_2025_split huggingface dataset:
The structural, morphological and magnetic characteristics of Mn‐implanted nonpolar a ‐plane GaN films
Authors: Sun Lili , Yan Fawang , Wang Junxi , Zeng Yiping , Wang Guohong , Li Jinmin 
Published: November 2008

AbstractDilute magnetic nonpolar GaN films have been fabricated by implanting Mn into unintentionally doped nonpolar a ‐plane GaN films at room temperature, and a subsequent rapid thermal annealing. The X‐ray diffraction analysis shows that after rapid thermal annealing the peak of the GaN X‐ray diffraction curve shifts to a lower angle, indicating a slight expansion of the GaN crystal lattice. Atomic force microscopy analysis shows that the annealing process does not change the morphology of the sample greatly. Magnetic property analysis indicates that the as‐annealed sample shows obvious ferromagnetic properties. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
High‐dielectric‐constant hafnium silicate insulator for low‐voltage pentacene field‐effect transistors
Authors: Yan Hu , Kagata Tsubasa , Arima Susumu , Sato Hiroshi , Okuzaki Hidenori 
Published: November 2008

AbstractWe prepared HfSiOx on a heavily doped n‐type silicon wafer by sputtering of a HfSi (50:50 at%) target using Ar:N2:O2 as carrier gas. The HfSiOx layer thus prepared was characterized by XPS, XRD, STEM and C –F measurements, indicating that the layer mainly consisted of 100 nm thick amorphous HfSiO5 with a dielectric constant ϵr = 7.7. The leakage current density was 1 nA/cm2 at an electric field of 2 MV/cm. We first fabricated top‐contact pentacene FETs using the high dielectric constant hafnium silicate as an insulator, coupled with a polymer microfiber‐based channel patterning technique. The pentacene FET showed well‐saturated output characteristics at low driving voltages, i.e. VD = –10 V and VG = –10 V, and hole mobility of 0.02 cm2/V s and on/off current ratio of 2600. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Scintillation properties of K2LaCl5:Ce microcrystals embedded in KCl host
Authors: Stryganyuk G. , Savchyn P. , Vistovskyy V. , Voloshinovskii A. , Antonyak O. , Birowosuto M. , Dorenbos P. 
Published: November 2008

AbstractScintillation properties under γ‐ray excitation and luminescence properties under X‐ray excitation of KCl with embedded K2LaCl5:Ce microphase crystals have been investigated. KCl–LaCl3(2 mol%)–CeCl3(0.1 mol% and 0.02 mol%) show scintillation yields of 15000–18000 photons/MeV with two decay time components of 300–420 ns and 1.2–1.9 µs. These properties compare with those of K2LaCl5:Ce bulk crystal. The luminescence study and scanning electron microscopy data indicate that the KCl–LaCl3–CeCl3 system contains K2LaCl5:Ce microcrystals of 10–50 μm size. The decrease of the intensity contribution and decay times of the slow component in the scintillation pulse of microcrystals compared with those in K2LaCl5:Ce single crystals are discussed. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Dielectric properties of highly c‐axis oriented chemical solution deposition derived SrBi4Ti4O15 thin films
Authors: Kambara Hiroyuki , Schneller Theodor , Sakabe Yukio , Waser Rainer 
Published: November 2008

AbstractC‐axis oriented thin films of SrBi4Ti4O15 were prepared by a chemical solution deposition method. The influence of precursor chemistry and processing conditions on the resulting film morphology and the dielectric properties of SrBi4Ti4O15 thin films were investigated. By controlling the film formation process, highly c‐axis oriented SrBi4Ti4O15 thin films on (111)Pt/Si substrates were obtained at temperatures of 600 °C and 700 °C. The dielectric constant of the films is about 200 and it is independent of film thickness ranging from 55 to 160 nm. The dielectric constant also shows stable value with an increase in temperature from 25 °C to 200 °C. The leakage current of the film at 125 °C is in the order of 10–7 A/cm2 at an applied electric field of 500 kV/cm. These films exhibit stable dielectric constant and excellent insulating properties. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The structures, thermochemistry, and electron affinities of hydrogenated silicon clusters Si6Hn/Si6H (n = 3–14)
Authors: Li Xiao‐Jun , Li Chun‐Ping , Yang Ju‐Cai , Jalbout Abraham F. 
Published: November 2008

AbstractThe hydrogenated silicon clusters structures, electron affinities, and dissociation energies of the Si6Hn/Si6H (n = 3−14) species have been systematically investigated by means of three density functional theory (DFT) methods. The basis set used in this work is of double‐ζ plus polarization quality with additional diffuse s‐ and p‐type functions, denoted DZP++. The geometries are fully optimized with each DFT method independently. Three different types of energy separations presented in this work are the adiabatic electron affinity (EAad), the vertical electron affinity (EAvert), and the vertical detachment energy (VDE). The first SiH dissociation energies De (Si6Hn→ Si6Hn−1+H) for the neutral Si6Hn and De (Si6H→Si6H+H) for the anionic Si6H species have also been reported. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2009
Theoretical study on HBC− and HCB− anions using multiconfiguration second‐order perturbation theory
Authors: Li Wen‐Zuo , Cheng Jian‐Bo , Li Qing‐Zhong , Gong Bao‐An , Sun Jia‐Zhong 
Published: November 2008

AbstractThe HBC− and HCB− anions have been studied using the complete active space self‐consistent field, CASPT2, and DFT/B3LYP methods with the contracted atomic natural orbital (ANO) and cc‐pVTZ basis sets. The geometries of all stationary points along the potential energy surfaces were optimized at the CASSCF/ANO and B3LYP/cc‐pVTZ levels. The ground state of HBC− is predicted to be X2ϕ state, which is different from the previously published results. The CASPT2/ANO potential energy curves (PECs) of isomerization reactions were calculated as a function of HBC bond angle and the PECs also show the 2ϕ state is the ground state of HBC− anion. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2009
Theoretical studies on QSAR and mechanism of 2‐indolinone derivatives as tubulin inhibitors
Authors: Liao Si Yan , Qian Li , Miao Ti Fang , Lu Hai Liang , Zheng Kang Cheng 
Published: November 2008

AbstractThe theoretical studies on three‐dimensional quantitative structure activity relationship (3D‐QSAR) and action mechanism of a series of 2‐indolinone derivatives as tubulin inhibitors against human breast cancer cell line MDA‐MB‐231 have been carried out. The established 3D‐QSAR model from the comparative molecular field analysis (CoMFA) shows not only significant statistical quality but also predictive ability, with high correlation coefficient (R2 = 0.986) and cross‐validation coefficient (q2 = 0.683). In particular, the appropriate binding orientations and conformations of these 2‐indolinone derivatives interacting with tubulin are located by docking study, and it is very interesting to find that the plot of the energy scores of these compounds in DOCK versus the corresponding experimental pIC50 values exhibits a considerable linear correlation. Therefore, the inhibition mechanism that 2‐indolinone derivatives were regarded as tubulin inhibitors can be theoretically confirmed. Based on such an inhibition mechanism along with 3D‐QSAR results, some important factors improving the activities of these compounds were discussed in detail. These factors can be summarized as follows: the H atom adopted as substituent R1, the substituent R2 with higher electropositivity and smaller bulk, the substituents R4–R6 (on the phenyl ring) with higher electropositivity and larger bulk, and so on. These results can offer useful theoretical references for understanding the action mechanism, designing more potent inhibitors, and predicting their activities prior to synthesis. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2009
Gas‐phase pyrolysis mechanisms of 3‐anilino‐1‐propanol: Density functional theory study
Authors: Zhao Jing , Tang Ming‐Sheng , Wei Dong‐Hui , Zhao Chu‐Feng , Zhang Wen‐Jing , Wang Hong‐Ming 
Published: November 2008

AbstractThe gas‐phase pyrolytic decomposition mechanisms of 3‐anilino‐1‐propanol with the products of aniline, ethylene, and formaldehyde orN‐methyl aniline and aldehyde were studied by density functional theory. The geometries of the reactant, transition states, and intermediates were optimized at the B3LYP/6‐31G (d, p) level. Vibration analysis was carried out to confirm the transition state structures, and the intrinsic reaction coordinate method was performed to search the minimum energy path. Four possible reaction channels are shown, including two concerted reactions of direct pyrolytic decomposition and two indirect channels in which the reactant first becomes a ring‐like intermediate, followed by concerted pyrogenation. One of the concerted reactions in the direct pyrolytic decomposition has the lowest activation barrier among all the four channels, and so, it occurs more often than others. The results appear to be consistent with the experimental outcomes. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2009
Progressive changes in phytoplankton community structure in urbanized lowland river floodplains—a multivariate approach
Authors: Tabasum Tanveera , Trisal C. L. 
Published: November 2008

AbstractPhytoplankton communities along the river Yamuna in Delhi stretch and its associated floodplain lakes showed considerable spatio‐temporal variations. Most of the species identified were cosmopolitan and typical of highly polluted rivers in tropical ecosystems. All the groups of phytoplankton with predominance of Cyanophyceae and some species of Chlorophyceae were distributed within the river stretch though with varying diversity and density. Relatively cleaner sites supported larger phytoplankton assemblages compared to those subjected to sewage outfalls and industrial effluents. Species elimination was observed mainly in the mid‐stretch and downstream of Okhla subjected to high loads of pollution. Co‐inertia analysis indicated significant co‐structures between water quality and species richness and density indicating water quality as the governing factor for phytoplankton distributions in the river stretch. Floodplain plays an important role in regenerating water quality thereby enhancing species richness and density. Floods play an important role in seasonal dynamics through dilution effects and promoting connectivity between river channel and floodplain lakes thereby facilitating species exchanges. Copyright © 2008 John Wiley & Sons, Ltd.
An ant colony optimization approach for reputation and quality‐of‐service‐based security in wireless sensor networks
Authors: Dhurandher Sanjay Kumar , Misra Sudip , Obaidat Mohammad S. , Gupta Nidhi 
Published: November 2008

AbstractIn wireless sensor networks (WSN), message security is an important concern. The protection of integrity and confidentiality of information and the protection from unauthorized access are important issues. However, due to factors such as resource limitations, absence of centralized access points, open wireless medium and small size of the sensor nodes, the implementation of security in WSN is a challenging task.In this paper, we propose a protocol, quality‐based distance vector routing (QDV), for securing WSN using concepts based on Ant colony optimization ACO [1]. Two fundamental parameters—quality‐of‐service (QoS) and reputation [2]—are used. The high value of reputation of a node signifies that the node is trusted and is more reliable for data communication purposes. As a node shows signs of misbehavior, its reputation decreases, which, in turn, affects its quality‐of‐security QSec [2], thereby disabling the malicious nodes from gaining access to the network. By incorporating these two factors, we are able to distinguish the nodes present in the network. We, then, present a method to achieve “equilibrium” where the node is able to guarantee that its neighbors are secure. Copyright © 2008 John Wiley & Sons, Ltd.
An effective defensive node against jamming attacks in sensor networks
Authors: Mpitziopoulos Aristides , Gavalas Damianos 
Published: November 2008

AbstractJamming is defined as the act of intentionally directing electromagnetic energy towards a communication system to disrupt or prevent signal transmission. In the context of wireless sensor networks (WSNs), jamming is the type of attack which interferes with the radio frequencies used by sensor nodes and may be viewed as a special case of denial of service (DoS) attacks. Herein, we outline the possible jamming attacks a WSN may encounter. The main contribution of this paper is the outline of the design specifications of a prototype node ‘Ares’ that effectively defends jamming attacks. Our focus is on frequency hopping spread spectrum (FHSS) and direct sequence spread spectrum (DSSS), two of the most effective countermeasures against jamming. The main novel aspect of Ares is that it uses a hybrid FHSS–DSSS approach to defend jamming attacks. We suggest the use of a specific FHSS technique in 5 GHz band with 51 frequency channels wherein the channel sequence is generated using a key (which derives from a secret word), known only to the sink and the sensor nodes, as a seed. Each channel uses DSSS modulation with 16‐bit pseudo noise (PN) code. The PN code derives from the same key used for FHSS channel generation. The pre‐eminence of our method against alternative anti‐jamming techniques is demonstrated through extensive simulation tests. Copyright © 2008 John Wiley & Sons, Ltd.
Bayesian propensity score analysis for observational data
Authors: McCandless Lawrence C. , Gustafson Paul , Austin Peter C. 
Published: November 2008

AbstractIn the analysis of observational data, stratifying patients on the estimated propensity scores reduces confounding from measured variables. Confidence intervals for the treatment effect are typically calculated without acknowledging uncertainty in the estimated propensity scores, and intuitively this may yield inferences, which are falsely precise. In this paper, we describe a Bayesian method that models the propensity score as a latent variable. We consider observational studies with a dichotomous treatment, dichotomous outcome, and measured confounders where the log odds ratio is the measure of effect. Markov chain Monte Carlo is used for posterior simulation. We study the impact of modelling uncertainty in the propensity scores in a case study investigating the effect of statin therapy on mortality in Ontario patients discharged from hospital following acute myocardial infarction. Our analysis reveals that the Bayesian credible interval for the treatment effect is 10 per cent wider compared with a conventional propensity score analysis. Using simulations, we show that when the association between treatment and confounders is weak, then this increases uncertainty in the estimated propensity scores. Bayesian interval estimates for the treatment effect are longer on average, though there is little improvement in coverage probability. A novel feature of the proposed method is that it fits models for the treatment and outcome simultaneously rather than one at a time. The method uses the outcome variable to inform the fit of the propensity model. We explore the performance of the estimated propensity scores using cross‐validation. Copyright © 2008 John Wiley & Sons, Ltd.
Proof of concept and dose estimation with binary responses under model uncertainty
Authors: Klingenberg B. 
Published: November 2008

AbstractThis article suggests a unified framework for testing Proof of Concept (PoC) and estimating a target dose for the benefit of a more comprehensive, robust and powerful analysis in phase II or similar clinical trials. From a pre‐specified set of candidate models, we choose the ones that best describe the observed dose–response. To decide which models, if any, significantly pick up a dose effect, we construct the permutation distribution of the minimum P‐value over the candidate set. This allows us to find critical values and multiplicity adjusted P‐values that control the familywise error rate of declaring any spurious effect in the candidate set as significant. Model averaging is then used to estimate a target dose. Popular single or multiple contrast tests for PoC, such as the Cochran–Armitage, Dunnett or Williams tests, are only optimal for specific dose–response shapes and do not provide target dose estimates with confidence limits. A thorough evaluation and comparison of our approach to these tests reveal that its power is as good or better in detecting a dose–response under various shapes with many more additional benefits: It incorporates model uncertainty in PoC decisions and target dose estimation, yields confidence intervals for target dose estimates and extends to more complicated data structures. We illustrate our method with the analysis of a Phase II clinical trial. Copyright © 2008 John Wiley & Sons, Ltd.
Robust outbreak surveillance of epidemics in Sweden
Authors: Frisén M. , Andersson E. , Schiöler L. 
Published: November 2008

AbstractOutbreak detection is of interest in connection with several diseases and syndromes. The aim is to detect the progressive increase in the incidence as soon as possible after the onset of the outbreak. A semiparametric method is applied to Swedish data on tularaemia and influenza. The method is constructed to detect a change from a constant level to a monotonically increasing incidence. If seasonal effects are present, the residuals from a model incorporating these can be used. The properties of the method are evaluated by application to Swedish data on tularaemia and influenza and by simulations. The suggested method is compared with subjective judgments as well as with other algorithms. The conclusion is that the method works well. A user‐friendly computer program is described. Copyright © 2008 John Wiley & Sons, Ltd.
Principles of complex systems for systems engineering
Authors: Sheard Sarah A , Mostashari Ali 
Published: November 2008

AbstractThis paper shows how three systems of types well known to systems engineers can be understood as complex systems. This is important because research in complex systems sciences is vibrant and provides critical insight, but if systems engineers do not understand the complex aspects of the systems they work with daily, they may not be able to use these research results. To date, systems engineering has been looking only at exploiting the “order” side of the order‐to‐chaos spectrum, and it is time now to understand and begin to utilize principles from the middle and from the chaos side of the spectrum. Three complex systems examples are INCOSE, the systems engineering process (such as a company's standard process), and air traffic control. INCOSE represents most volunteer organizations and social groups. Most systems engineers do not realize that the systems engineering process for a company is a network that can be studied by complex systems methods. Air traffic control may come closest to many systems engineers' definition of a system. This paper provides principles of complex systems based on a variety of sources, and shows the application of complex systems to one of the examples. © 2008 Wiley Periodicals, Inc. Syst Eng
Prognostic Factors After Resection of Pancreatic Cancer
Authors: Ueda Michio , Endo Itaru , Nakashima Masayuki , Minami Yuta , Takeda Kazuhisa , Matsuo Kenichi , Nagano Yasuhiko , Tanaka Kuniya , Ichikawa Yasushi , Togo Shinji , Kunisaki Chikara , Shimada Hiroshi 
Published: November 2008

AbstractObjectivesThe purpose of this study was to identify important prognostic factors related to the status of a pancreatic tumor, its treatment, and the patient’s general condition.MethodsBetween April 1992 and December 2006, 140 patients underwent a pancreatic resection for invasive ductal carcinoma. Prognostic factors were defined by univariate and multivariate analyses.ResultsThe study included 103 tumors in the head of the pancreas and 37 tumors in the body or tail. The median survival time and the actuarial 5‐year survival rate for all patients were 14.5 months and 12.3%, respectively. Using the significant prognostic factors identified by univariate analysis, multivariate analysis revealed that a preoperative serum CA19‐9 concentration >100 U/ml (HR = 1.84, p = 0.0074), a tumor size >3 cm (HR = 1.74, p = 0.0235), venous involvement (HR = 2.39, p = 0.0006), a transfusion requirement of ≥1000 ml (HR = 2.23, p = 0.0006), and a serum albumin concentration on 1 postoperative month (1POM) < 3 g/dl (HR = 2.40, p = 0.0009) were significant adverse prognostic factors. The presence of hypoalbuminemia on 1POM significantly correlated with a longer surgical procedure (p = 0.0041), extended nerve plexus resection around the superior mesenteric artery (p = 0.0456), and a longer postoperative hospital stay (p = 0.0063).ConclusionTo improve long‐term survival, preserving the patient’s general condition by performing a curative resection with a short operation time and minimal blood loss should be the most important principle in the surgical treatment of pancreatic cancer.
From Molecular Fossils of Bacterial Hopanoids to the Formation of Isoprene Units: Discovery and Elucidation of the Methylerythritol Phosphate Pathway
Authors: Rohmer Michel 
Published: November 2008

AbstractInvestigations on the biosynthesis of bacterial triterpenoids of the hopane series led to the unexpected discovery of an alternative mevalonate independent pathway for the formation of isoprene units. Methylerythritol phosphate, already presenting the C5 branched isoprene skeleton, is the key intermediate. This pathway was independently characterized in ginkgo embryos for the formation of diterpenoids. It is present in most bacteria and in the plastids of all organisms belonging to phototrophic phyla. The key steps of the discovery and elucidation of this metabolic route are presented in this review.
The antioxidant effects of quercetin metabolites on the prevention of high glucose-induced apoptosis of human umbilical vein endothelial cells
Authors: Chao Chia-Lun , Hou Yu-Chi , Lee Chao Pei-Dawn , Weng Ching-Sung , Ho Feng-Ming 
Published: November 2008

Diabetes mellitus is an important risk factor for CVD. A previous study showed that high glucose induced the apoptosis of human umbilical vein endothelial cells (HUVEC) via the sequential activation of reactive oxygen species, Jun N-terminal kinase (JNK) and caspase-3. The apoptosis cascade could be blocked by ascorbic acid at the micromolar concentration (100 μm). In addition to ascorbic acid, quercetin, the most abundant dietary flavonol, has been recently actively studied in vascular protection effects due to its antioxidant effect at low micromolar concentrations (10–50 μm). Quercetin sulfate/glucuronide, the metabolite of quercetin in blood, however, has been rarely evaluated. In the present study, we investigated the effect of quercetin sulfate/glucuronide on the prevention of high glucose-induced apoptosis of HUVEC. HUVEC were treated with media containing high glucose (33 mm) in the presence or absence of ascorbic acid (100 μm) or quercetin sulfate/glucuronide (100 nm, 300 nm and 1 μm). For the detection of apoptosis, a cell death detection ELISA assay was used. The level of intracellular H2O2 was measured by flow cytometry. JNK and caspase-3 were evaluated by a kinase activity assay and Western blot analysis. The results showed that high glucose-induced apoptosis was inhibited by quercetin sulfate/glucuronide in a dose-dependent manner. The effect of quercetin sulfate/glucuronide on H2O2 quenching, inhibition of JNK and caspase-3 activity at the nanomolar concentration (300 nm) was similar to that of ascorbic acid at the micromolar concentration (100 μm). The findings of the present study may shed light on the pharmacological application of quercetin in CVD.