bluuebunny/crossref_metadata_2025 huggingface dataset:
In vivo hepatic endoplasmic reticulum stress in patients with chronic hepatitis C
Authors: Asselah Tarik , Bièche Ivan , Mansouri Abdellah , Laurendeau Ingrid , Cazals‐Hatem Dominique , Feldmann Gérard , Bedossa Pierre , Paradis Valérie , Martinot‐Peignoux Michelle , Lebrec Didier , Guichard Cécile , Ogier‐Denis Eric , Vidaud Michel , Tellier Zéra , Soumelis Vassili , Marcellin Patrick , Moreau Richard
Published: February 2010

In hepatocytes, the accumulation of unfolded proteins in the endoplasmic reticulum (ER) causes ER stress and the unfolded protein response (UPR), mediated by the ER‐resident stress sensors ATF‐6, IRE1, and PERK. UPR‐responsive genes are involved in the fate of ER‐stressed cells. Cells carrying hepatitis C virus (HCV) subgenomic replicons exhibit in vitro ER stress and suggest that HCV inhibits the UPR. Since in vivo ER homeostasis is unknown in livers with chronic HCV infection, we investigated ER stress and the UPR in liver samples from untreated patients with chronic hepatitis C (CHC), in comparison with normal livers. Electron microscopy, western blotting, and real‐time RT‐PCR were used in liver biopsy specimens. Electron microscopy identified features showing ER stress in hepatocyte samples from patients with CHC; however, ‘ER‐stressed’ hepatocytes were found in clusters (3‐5 cells) that were scattered in the liver parenchyma. Western blot analysis confirmed the existence of hepatic ER stress by showing activation of the three ER stress sensors ATF‐6, IRE1, and PERK in CHC. Real‐time RT‐PCR showed no significant induction of UPR‐responsive genes in CHC. In contrast, genes involved in the control of diffuse processes such as liver proliferation, inflammation, and apoptosis were significantly induced in CHC. In conclusion, livers from patients with untreated CHC exhibit in vivo hepatocyte ER stress and activation of the three UPR sensors without apparent induction of UPR‐responsive genes. This lack of gene induction may be explained by the inhibiting action of HCV per se (as suggested by in vitro studies) and/or by our finding of the localized nature of hepatocyte ER stress. Copyright © 2010 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Improving surface quality of microcellular injection molded parts through mold surface temperature manipulation with thin film insulation
Authors: Lee Jungjoo , Turng Lih‐Sheng
Published: February 2010

Microcellular injection molding offers many advantages such as material and energy savings, reduced cycle times, and excellent dimensional stability. However, typical surface characteristics of microcellular injection molded parts—such as gas flow and swirl marks and a lack of smoothness—have precluded the process from being used for applications where surface appearance is important. This article presents an insulator‐assisted method that has been shown to improve the surface quality of microcellular injection molded parts significantly. By incorporating a thin film (75–225 μm) of polytetrafluoroethylene (PTFE) insulator on the mold surface, the polymer melt–insulator interfacial temperature can be manipulated and can be kept high enough during mold filling to reduce or eliminate swirl marks on the surface. The experimental results in terms of surface roughness and surface profile of conventional and microcellular injection molded parts with and without the insulator film are discussed. Thermal analyses of the corresponding microcellular injection molding experiments were performed to elucidate the correlation between film thickness, interfacial temperature, and the surface quality. The effect of insulator on the cooling time increase is also analyzed and presented. POLYM. ENG. SCI., 2010. © 2010 Society of Plastics Engineers
Spinodal regions due to disorder in superferromagnets
Authors: Kondratyev V. N. , Blanchard Ph.
Published: February 2010

Inter‐ and intra‐dot structures of an assembly of ferromagnetically coupled quantum dots are analyzed within the randomly jumping interacting moments (RJIM) model including quantum effects due to the dot discrete levels and disorder. At the magnetic jump anomalies due to quantization the magnetic state equation (MSE) and phase diagrams are found to indicate an existence of spinodal regions and critical points. Arrays of dots with multiple magnetic response anomalies are predicted to display some specific features. In a case of weak coupling such arrays exhibit the well‐separated instability regions surrounding the anomaly positions. With increase in coupling we observe further structure modification, plausibly, of bifurcation type. At strong coupling the instability region becomes wide while the stable regime arises as a narrow islands at small disorders.
Photo‐induced insulator–metal transition and magnetic solitons in the perovskite PrCaMnO
Authors: Kanazawa Ikuzo
Published: February 2010

We have discussed the percolation‐like insulator–metal transition, the conduction mechanism, and localization of photo‐induced magnetic solitons with the hole in the perovskite PrCaMnO by using quantized massive gauge fields, which are introduced theoretically in the path‐integral method, around the photohole.
Quantum criticality and global phase diagram of magnetic heavy fermions
Authors: Si Qimiao
Published: February 2010

Quantum criticality describes the collective fluctuations of matter undergoing a second‐order phase transition at zero temperature. It is being discussed in a number of strongly correlated electron systems. A prototype case occurs in the heavy fermion metals, in which antiferromagnetic quantum critical points (QCPs) have been explicitly observed. Here, I address two types of antiferromagnetic QCPs. In addition to the standard description based on the fluctuations of the antiferromagnetic order, a local QCP is also considered. It contains inherently quantum modes that are associated with a critical breakdown of the Kondo effect. Across such a QCP, there is a sudden collapse of a large Fermi surface to a small one. I also consider the proximate antiferromagnetic and paramagnetic phases, and these considerations lead to a global phase diagram. Finally, I discuss the pertinent experiments and outline some directions for future studies.
Proposed best practice for statisticians in the reporting and publication of pharmaceutical industry‐sponsored clinical trials
Authors: Matcham James , Julious Steven , Pyke Stephen , O'Kelly Michael , Todd Susan , Seldrup Jorgen , Day Simon
Published: February 2010

In this paper we set out what we consider to be a set of best practices for statisticians in the reporting of pharmaceutical industry‐sponsored clinical trials. We make eight recommendations covering: author responsibilities and recognition; publication timing; conflicts of interest; freedom to act; full author access to data; trial registration and independent review. These recommendations are made in the context of the prominent role played by statisticians in the design, conduct, analysis and reporting of pharmaceutical sponsored trials and the perception of the reporting of these trials in the wider community. Copyright © 2010 John Wiley & Sons, Ltd.
Persistence of increased uterine artery resistance in the third trimester and pregnancy outcome
Authors: Ghi T. , Contro E. , Youssef A. , Giorgetta F. , Farina A. , Pilu G. , Pelusi G.
Published: February 2010

Objective

To evaluate whether the persistence of abnormal findings in the third trimester following increased uterine artery (UtA) resistance in the second trimester is related to adverse pregnancy outcome.

Methods

Low‐risk nulliparous women with increased UtA mean pulsatility index (PI) at 20–22 weeks underwent repeat Doppler interrogation at 26–28 weeks and were divided into two groups: those with persistently abnormal Doppler and those with normalized UtA findings. Pregnancy outcome was noted for all patients and compared with that of 104 controls.

Results

We examined 104 women with increased UtA resistance in the second trimester and in 62 (59.6%) cases the abnormal uteroplacental Doppler findings persisted to 26–28 weeks. Compared with controls and with patients with normalized Doppler at the third‐trimester scan, patients with persistently abnormal Doppler results had a significantly higher risk of pre‐eclampsia (10/62 vs. 1/104, P = 0.002 and 10/62 vs. 1/42, P = 0.047, respectively), small‐for‐gestational age (SGA) fetus (20/62 vs. 1/104, P < 0.001 and 20/62 vs. 4/42; P = 0.007, respectively) and admission of the infant to a neonatal intensive care unit (16/62 vs. 4/104; P < 0.001 and 16/62 vs. 1/42; P < 0.001, respectively). Compared with controls, cases with normalization had an increased risk of SGA (4/42 vs. 1/104, P = 0.03), but there were no significant differences for the other outcome measures.

Conclusions

In low‐risk nulliparous women with increased UtA resistance in the second trimester, the persistence of abnormal Doppler findings at 26–28 weeks is associated with an increased risk of obstetric complications when compared with both controls and patients with third‐trimester Doppler normalization. Copyright © 2010 ISUOG. Published by John Wiley & Sons, Ltd.
Syntactic bootstrapping
Authors: Fisher Cynthia , Gertner Yael , Scott Rose M. , Yuan Sylvia
Published: February 2010

Children use syntax to guide verb learning in a process known as syntactic bootstrapping. Recent work explores how syntactic bootstrapping works—how it begins, and how it interacts with progress in syntax acquisition. We review evidence for three claims about the mechanisms and representations underlying syntactic bootstrapping: (1) Learners are biased to represent linguistic knowledge in a usefully abstract mental vocabulary, permitting rapid generalization of newly acquired syntactic knowledge to new verbs. (2) Toddlers collect information about each verb's combinatorial behavior in sentences based on listening experience, before they know anything about the verb's semantic content. (3) Syntactic bootstrapping begins with an unlearned bias to map nouns in sentences one‐to‐one onto the participant roles in events. These lines of evidence point toward a picture of early verb learning in which shallow structural analyses of sentences are intrinsically meaningful to learners, and in which information about verbs' combinatorial behavior pervades the lexicon from very early in development. Copyright © 2010 John Wiley & Sons, Ltd.

This article is categorized under:

Linguistics > Language in Mind and Brain
Evaluation of adrenocortical function in Florida manatees (Trichechus manatus latirostris)
Authors: Tripp Kathleen M. , Verstegen John P. , Deutsch Charles J. , Bonde Robert K. , Wit Martine de , Manire Charles A. , Gaspard Joseph , Harr Kendal E.
Published: February 2010

The study objectives were to determine the predominant manatee glucocorticoid; validate assays to measure this glucocorticoid and adrenocorticotropic hormone (ACTH); determine diagnostic thresholds to distinguish physiological vs. pathological concentrations; identify differences associated with sex, age class, female reproductive status, capture time, and lactate; and determine the best methods for manatee biologists and clinicians to diagnose stress. Cortisol is the predominant manatee glucocorticoid. IMMULITE 1000 assays for cortisol and ACTH were validated. Precision yielded intra‐ and inter‐assay coefficients of variation for serum cortisol: ≤23.5 and ≤16.7%; and ACTH: ≤6.9 and ≤8.5%. Accuracy resulted in a mean adjustedR2≥0.87 for serum cortisol and ≥0.96 for ACTH. Assay analytical sensitivities for cortisol (0.1 µg/dl) and ACTH (10.0 pg/ml) were verified. Methods were highly correlated with another IMMULITE 1000 for serum cortisol (r=0.97) and ACTH (r=0.98). There was no significant variation in cortisol or ACTH with sex or age class and no correlation with female progesterone concentrations. Cortisol concentrations were highest in unhealthy manatees, chronically stressed by disease or injury. ACTH was greatest in healthy free‐ranging or short‐term rehabilitating individuals, peracutely stressed by capture and handling. Cortisol concentrations ≥1.0 µg/dl were diagnostic of chronic stress; ACTH concentrations ≥87.5 pg/ml were diagnostic of peracute stress. In healthy long‐term captive manatees, cortisol (0.4±0.2 µg/dl) and ACTH (47.7±15.9 pg/ml) concentrations were lower than healthy free‐ranging, short‐term rehabilitated or unhealthy manatees. Capture time was not significantly correlated with cortisol; ACTH correlation was borderline significant. Cortisol and ACTH were positively correlated with lactate. Zoo Biol 30:17–31, 2011. © 2010 Wiley‐Liss, Inc.
Risk Factors for Massive Bleeding during Major Hepatectomy
Authors: Shirabe Ken , Kajiyama Kiyoshi , Harimoto Norifumi , Tsujita Eiji , Wakiyama Shigeki , Maehara Yoshihiko
Published: February 2010

Background

Massive bleeding during hepatectomy is a risk for mortality and morbidity. We examined the risk factors for massive bleeding and their correlations with outcomes.

Methods

The study was a retrospective case series. Among 353 consecutively hepatectomized patients, the mean estimated blood loss (EBL) was 825 ml. Ten patients (2.8%) experienced EBL of between 3000 and 5000 ml. Five patients (1.4%) experienced massive EBL defined as more than 5000 ml, and all five patients had undergone right major hepatectomy (RMH) for primary liver cancer (PLC). All the patients with PLC who underwent RMH were divided into two groups: group I with EBL ≤ 5000 ml (n = 19) and group II with EBL > 5000 ml (n = 5). Perioperative factors regarding massive bleeding and operative mortality and morbidity were compared between the two groups.

Results

Among the ten patients who experienced EBL of between 3000 and 5000 ml, three had partial hepatectomy of no more than subsegmentectomy of the paracaval portion of the caudate lobe and three had central bisegmentectomy. The mean tumor size was 7.9 ± 4.7 cm in group I and 15.1 ± 2.2 cm in group II (P = 0. 0034). Tumor compression of the inferior vena cava (IVC) on CT scans was observed in all patients in group II, but in no patients in group I (P < 0.0001). Four of five patients in group II received surgery through an anterior approach. The liver‐hanging maneuver (LHM) was applied in 14 of 19 patients (74%) in group I but could not be applied in group II (P = 0.0059). No postoperative and in‐hospital mortalities occurred in group II and there were no significant differences in the incidence of mortality and morbidity between the groups.

Conclusions

RMH for large PLCs, tumor compression of the IVC, and an anterior approach without the LHM are risks for massive bleeding during hepatectomy. Preparation of rapid infusion devices in these cases is necessary to avoid prolonged hypotension.
Rice Germin-Like Proteins: Allelic Diversity and Relationships to Early Stress Responses
Authors: Davidson Rebecca M. , Manosalva Patricia M. , Snelling Jacob , Bruce Myron , Leung Hei , Leach Jan E.
Published: February 2010

Germin-like protein (GLP) markers were associated with quantitative trait loci (QTL) for resistance to the rice blast pathogen, Magnaporthe oryzae in multiple rice (Oryza sativa) mapping populations. Twelve paralogous OsGLP gene family members are located within the physical QTL region on chromosome 8, and gene silencing studies suggest that they contribute collectively to the resistance phenotype. We compared sequence and expression profiles of OsGLP alleles in two resistant and two susceptible parental rice lines to find functional polymorphisms that correlated with the resistant phenotype. Based on coding and promoter sequences, the genes belong to two germin subfamily groups (GER3 and GER4). OsGLP members from both subfamilies were constitutively expressed and developmentally regulated in all cultivars. Transient induction above constitutive levels was observed for some OsGLPs, especially GER4 subfamily members, at early time points after M. oryzae infection and mechanical wounding. Varying 5′ regulatory regions and differential expression of some family members between resistant and susceptible cultivars corresponded with differential hydrogen peroxide (H2O2) accumulation after the same stimuli. OsGLP of both GER subfamilies localized to the plant cell wall. The protein location and early gene induction suggest that OsGLPs protect rice leaves at early stages of infection before fungal penetration and subsequent ingress. Our data suggest that regulation of OsGLP genes defines resistant versus susceptible phenotypes.
Beneficial influence of dietary spices on the ultrastructure and fluidity of the intestinal brush border in rats
Authors: Prakash Usha N. S. , Srinivasan Krishnapura
Published: February 2010

The beneficial influence of three common spices was examined in experimental rats on: (i) the membrane fluidity of intestinal brush-border membranes (BBM), (ii) the activity of intestinal membrane-bound enzymes, and (iii) ultrastructural alterations in the intestinal epithelium. Groups of male Wistar rats were maintained on dietary black pepper (0·5 %), red pepper (3·0 %), ginger (0·05 %) and spice bioactive compounds piperine (0·02 %) and capsaicin (0·01 %) for 8 weeks. A membrane fluidity study using an apolar fluorescent probe showed increased BBM fluidity in all the spice-fed animals. This was corroborated by a decreased cholesterol:phospholipid ratio in the jejunal and ileal regions of the intestine. These dietary spices stimulated the activities of BBM enzymes (glycyl-glycine dipeptidase, leucine amino peptidase and γ-glutamyl transpeptidase) in the jejunal mucosa, suggesting a modulation in membrane dynamics due to the apolar spice bioactive compounds interacting with surrounding lipids and hydrophobic portions in the protein vicinity, which may decrease the tendency of membrane lipids to act as steric constraints to enzyme proteins and thus modify enzyme conformation. Scanning electronic microscopy of the intestinal villi in these spice treatments revealed alterations in the ultrastructure, especially an increase in microvilli length and perimeter which would mean a beneficial increase in the absorptive surface of the small intestine, providing for an increased bioavailability of micronutrients. Thus, dietary spices (black pepper, red pepper and ginger) were evidenced to induce alterations in BBM fluidity and passive permeability property, associated with the induction of an increased microvilli length and perimeter, resulting in an increased absorptive surface of the small intestine.
Public Protestantism and Mission in Germany's Thuringian States, 1871–1914
Authors: Mathieu Edward C.
Published: February 2010

Bourgeois Germans engaged with considerable urgency in religious debate in the public discourse of Imperial Germany. There were those who saw this religious conversation in a negative light. As socialist leader Wilhelm Liebknecht quipped, “Religious questions have been handled with greater fervor in no epoch of German history than in this moment. One feels oneself transported into the most befuddled times of the Reformation, so widespread is the incessant religious squabbling.” Bourgeois Protestants, the primary interlocutors in religious discourse, viewed the growing religious discussion of the world's problem more positively.
Variability of fouling communities in the Mar Piccolo of Taranto (Northern Ionian Sea, Mediterranean Sea)
Authors: Pierri Cataldo , Longo Caterina , Giangrande Adriana
Published: February 2010

In order to investigate the intensity and variability of fouling recruitment on artificial hard substrates, three sites were chosen in the First Inlet of the Mar Piccolo of Taranto (Southern Italy, Ionian Sea). Taxa richness and percentage coverage were examined in three different sampling times within each site. Differences were tested both by univariate and multivariate statistical analysis (ANOVA, SIMPER and MDS). The results show that each site seems to be characterized by its own structural make-up over the whole period of observation, underlying the presence of large-scale variability. By contrast, variability on a smaller scale within each site (replicates) appeared less marked, both in space and time. A set of a quite stable group of species characterized each site. Differences between sites were maintained over time with a difference in community evolution although with a tendency towards a higher similarity in species composition along the time.
Has Man an Essence?
Authors: Quinton Anthony
Published: February 2010

Much of recent ethics has been thoroughly formalistic in character. In the first place it has confined itself to the investigation of the general logical properties of møral discourse and has largely ignored the broad psychological context of motives and purposes in which that kind of discourse has its life. Secondly, it has sought to distinguish the field of discourse that it takes as its subject-matter in a formalistic way, in terms of such properties as its universalisability, its autonomy and its overridingness, without reference to the concrete and specific human interests with which moral discourse is connected and which it might serve to promote.
Respiratory syncytial virus and complete heart block in a child
Authors: Menahem Samuel
Published: February 2010

The common respiratory syncytial virus has been associated with cardiac involvement, usually tachyarrhythmias and occasionally myocarditis. A child is described who probably developed a complete heart block following respiratory syncytial bronchiolitis. Such an association needs to be considered if the heart is structurally normal and there is no evidence of a congenital heart block in a setting of maternal anti-Ro and anti-La antibodies.
Jet and prolongation spaces
Authors: Moosa Rahim , Scanlon Thomas
Published: February 2010

The notion of a prolongation of an algebraic variety is developed in an abstract setting that generalizes the difference and (Hasse) differential contexts. An interpolating map that compares these prolongation spaces with algebraic jet spaces is introduced and studied.
Fire‐climate interactions in the American West since 1400 CE
Authors: Trouet Valerie , Taylor Alan H. , Wahl Eugene R. , Skinner Carl N. , Stephens Scott L.
Published: February 2010

Despite a strong anthropogenic fingerprint on 20th Century wildland fire activity in the American West, climate remains a main driver. A better understanding of the spatio‐temporal variability in fire‐climate interactions is therefore crucial for fire management. Here, we present annually resolved, tree‐ring based fire records for four regions in the American West that extend back to 1400 CE. In all regions, years with high fire activity were characterized by widespread yet regionally distinct summer droughts. Overall fire activity was high in late Medieval times, when much of the American West was affected by mega‐droughts. A distinct decline in fire activity in the late 16th Century corresponds with anomalously low temperatures during the Little Ice Age and a decline in Native American fire use. The high spatiotemporal resolution of our fire record discloses a time‐frequency dependent climatic influence on wildfire regimes in the American West that needs to be accounted for in fire models.
High duty factor plasma generator for CERN’s Superconducting Proton Linac
Authors: Lettry J. , Kronberger M. , Scrivens R. , Chaudet E. , Faircloth D. , Favre G. , Geisser J.-M. , Küchler D. , Mathot S. , Midttun O. , Paoluzzi M. , Schmitzer C. , Steyaert D.
Published: February 2010

CERN’s Linac4 is a 160 MeV linear accelerator currently under construction. It will inject negatively charged hydrogen ions into CERN’s PS-Booster. Its ion source is a noncesiated rf driven H− volume source directly inspired from the one of DESY and is aimed to deliver pulses of 80 mA of H− during 0.4 ms at a 2 Hz repetition rate. The Superconducting Proton Linac (SPL) project is part of the luminosity upgrade of the Large Hadron Collider. It consists of an extension of Linac4 up to 5 GeV and is foreseen to deliver protons to a future 50 GeV synchrotron (PS2). For the SPL high power option (HP-SPL), the ion source would deliver pulses of 80 mA of H− during 1.2 ms and operate at a 50 Hz repetition rate. This significant upgrade motivates the design of the new water cooled plasma generator presented in this paper. Its engineering is based on the results of a finite element thermal study of the Linac4 H− plasma generator that identified critical components and thermal barriers. A cooling system is proposed which achieves the required heat dissipation and maintains the original functionality. Materials with higher thermal conductivity are selected and, wherever possible, thermal barriers resulting from low pressure contacts are removed by brazing metals on insulators. The AlN plasma chamber cooling circuit is inspired from the approach chosen for the cesiated high duty factor rf H− source operating at SNS.
Ion sources for MedAustron
Authors: Lettry J. , Penescu L. , Wallner J. , Sargsyan E.
Published: February 2010

The MedAustron Ion therapy center will be constructed in Wiener Neustadt (Austria) in the vicinity of Vienna. Its accelerator complex consists of four ion sources, a linear accelerator, a synchrotron, and a beam delivery system to the three medical treatment rooms and to the research irradiation room. The ion sources shall deliver beams of H31+, C4+, and light ions with utmost reliability and stability. This paper describes the features of the ion sources presently planned for the MedAustron facility, such as ion source main parameters, gas injection, temperature control, and cooling systems. A dedicated beam diagnostics technique is proposed in order to characterize electron cyclotron resonance (ECR) ion beams; in the first drift region after the ion source, a fraction of the mixed beam is selected via moveable aperture. With standard beam diagnostics, we then aim to produce position-dependant observables such as ion-current density, beam energy distribution, and emittance for each charge states to be compared to simulations of ECR e-heating, plasma simulation, beam formation, and transport.
Laser plasma in a magnetic field
Authors: Kondo K. , Kanesue T. , Tamura J. , Dabrowski R. , Okamura M.
Published: February 2010

Laser ion source (LIS) is a candidate among various heavy ion sources. A high density plasma produced by Nd:yttrium aluminum garnet laser with drift velocity realizes high current and high charge state ion beams. In order to obtain higher beam current, we made experiments using the LIS with a magnetic field by which a confinement effect can make higher beam current. We measured total current by Faraday cup and analyzed charge distribution by electrostatic ion analyzer. It is shown that the ion beam charge state is higher by a permanent magnet.
Aberration of a negative ion beam caused by space charge effect
Authors: Miyamoto K. , Wada S. , Hatayama A.
Published: February 2010

Aberrations are inevitable when the charged particle beams are extracted, accelerated, transmitted, and focused with electrostatic and magnetic fields. In this study, we investigate the aberration of a negative ion accelerator for a neutral beam injector theoretically, especially the spherical aberration caused by the negative ion beam expansion due to the space charge effect. The negative ion current density profiles with the spherical aberration are compared with those without the spherical aberration. It is found that the negative ion current density profiles in a log scale are tailed due to the spherical aberration.
A two step method in inverse scattering problem for a crack
Authors: Lee Kuo-Ming
Published: February 2010

In this paper, we present a method for solving a time-harmonic acoustic inverse scattering problem for a sound-soft crack in R2. Based on the integral equation method, our method splits the nonlinear, severely ill-posed inverse problem into a linear well-posed direct problem and a nonlinear ill-posed problem. At this setting, not only the regularized Newton’s method can still be used to solve the inverse problem numerically but also with the advantage of keeping the structure of the algorithm simple and efficient.
Dynamics of reactive high-power impulse magnetron sputtering discharge studied by time- and space-resolved optical emission spectroscopy and fast imaging
Authors: Hala M. , Viau N. , Zabeida O. , Klemberg-Sapieha J. E. , Martinu L.
Published: February 2010

Time- and space-resolved optical emission spectroscopy and fast imaging were used for the investigation of the plasma dynamics of high-power impulse magnetron sputtering discharges. 200 μs pulses with a 50 Hz repetition frequency were applied to a Cr target in Ar, N2, and N2/Ar mixtures and in a pressure range from 0.7 to 2.66 Pa. The power density peaked at 2.2–6 kW cm−2. Evidence of dominating self-sputtering was found for all investigated conditions. Up to four different discharge phases within each pulse were identified: (i) the ignition phase, (ii) the high-current metal-dominated phase, (iii) the transient phase, and (iv) the low-current gas-dominated phase. The emission of working gas excited by fast electrons penetrating the space in-between the electrodes during the ignition phase spread far outwards from the target at a speed of 24 km s−1 in 1.3 Pa of Ar and at 7.5 km s−1 in 1.3 Pa of N2. The dense metal plasma created next to the target propagated in the reactor at a speed ranging from 0.7 to 3.5 km s−1, depending on the working gas composition and the pressure. In fact, it increased with higher N2 concentration and lower pressure. The form of the propagating plasma wave changed from a hemispherical shape in Ar, to a droplike shape extending far from the target in N2. An important N2 emission rise in the latter case was detected during the transition at the end of the metal-dominated phase.
Analysis of neutral particle recycling and pedestal fueling in a H-mode DIII-D discharge
Authors: Friis Z. W. , Stacey W. M. , Leonard A. W. , Rensink M. E.
Published: February 2010

A detailed analysis of neutral atom recycling and pedestal fueling in a DIII-D [J. Luxon, Nucl. Fusion 42, 614 (2002)] high-confinement mode discharge is presented. Experimental data and two-dimensional (2D) edge plasma fluid code calculations are employed to provide ion wall recycling and recombination neutral sources and background edge plasma parameters for a 2D edge neutral code calculation of detailed neutral density, ionization, and charge-exchange distributions throughout the edge pedestal, scrape-off layer and surrounding halo region, divertor, and private flux regions. The effectiveness of the different neutral sources for fueling the confined plasma is evaluated.
Positioning effects on quantum dot solar cells grown by molecular beam epitaxy
Authors: Zhou D. , Vullum P. E. , Sharma G. , Thomassen S. F. , Holmestad R. , Reenaas T. W. , Fimland B. O.
Published: February 2010

We report current-voltage and spectral response characteristics of high density InAs/GaAs quantum dot (QD) solar cells with different positions where dots are located. The short circuit current density (Jsc), open circuit voltage (Voc), and external quantum efficiency of these cells under air mass 1.5 are presented and compared with a GaAs reference cell. An extended photoresponse in contrast to the GaAs reference cell was confirmed for all these cells. The effect of inserting QD layers into emitter and base region on device performance is shown. The Jsc is reduced, while the Voc is maintained. The cell with QDs located toward the base side shows better performance, confirmed by both current-voltage and spectral response measurements.
Photoluminescence from exciton-exciton scattering in a GaAs1−xNx thin film
Authors: Hashimoto J. , Maeda Y. , Nakayama M.
Published: February 2010

We have investigated photoluminescence (PL) properties under high-density-excitation conditions at 10 K in a GaAs1−xNx thin film (x=0.008) with a narrow band-gap energy of 1.34 eV. A PL band was observed with a threshold-like nature, and its intensity was found to exhibit quadratic dependence on the excitation power. At the threshold excitation power, the PL-peak energy is lower than the energy of the fundamental exciton by the magnitude of the exciton binding energy that is ∼4 meV. The results described above indicate that the PL band originates from exciton-exciton scattering, the so-called P emission, which is typically observed in wide-gap semiconductors with large exciton binding energies. Furthermore, we have confirmed the existence of optical gain in the energy region of the P band using a variable-stripe-length method.
Dielectric and piezoelectric properties of lead-free (Bi,Na)TiO3-based thin films
Authors: Abazari M. , Safari A. , Bharadwaja S. S. N. , Trolier-McKinstry S.
Published: February 2010

Dielectric and piezoelectric properties of morphotropic phase boundary (Bi,Na)TiO3–(Bi,K)TiO3–BaTiO3 epitaxial thin films deposited on SrRuO3 coated SrTiO3 substrates were reported. Thin films of 350 nm thickness exhibited small signal dielectric permittivity and loss tangent values of 750 and 0.15, respectively, at 1 kHz. Ferroelectric hysteresis measurements indicated a remanent polarization value of 30 μC/cm2 with a coercive field of 85–100 kV/cm. The thin film transverse piezoelectric coefficient (e31,f) of these films after poling at 600 kV/cm was found to be −2.2 C/m2. The results indicate that these BNT-based thin films are a potential candidate for lead-free piezoelectric devices.
Gradient-based multiconfiguration Shepard interpolation for generating potential energy surfaces for polyatomic reactions
Authors: Tishchenko Oksana , Truhlar Donald G.
Published: February 2010

This paper describes and illustrates a way to construct multidimensional representations of reactive potential energy surfaces (PESs) by a multiconfiguration Shepard interpolation (MCSI) method based only on gradient information, that is, without using any Hessian information from electronic structure calculations. MCSI, which is called multiconfiguration molecular mechanics (MCMM) in previous articles, is a semiautomated method designed for constructing full-dimensional PESs for subsequent dynamics calculations (classical trajectories, full quantum dynamics, or variational transition state theory with multidimensional tunneling). The MCSI method is based on Shepard interpolation of Taylor series expansions of the coupling term of a 2×2 electronically diabatic Hamiltonian matrix with the diagonal elements representing nonreactive analytical PESs for reactants and products. In contrast to the previously developed method, these expansions are truncated in the present version at the first order, and, therefore, no input of electronic structure Hessians is required. The accuracy of the interpolated energies is evaluated for two test reactions, namely, the reaction OH+H2→H2O+H and the hydrogen atom abstraction from a model of α-tocopherol by methyl radical. The latter reaction involves 38 atoms and a 108-dimensional PES. The mean unsigned errors averaged over a wide range of representative nuclear configurations (corresponding to an energy range of 19.5 kcal/mol in the former case and 32 kcal/mol in the latter) are found to be within 1 kcal/mol for both reactions, based on 13 gradients in one case and 11 in the other. The gradient-based MCMM method can be applied for efficient representations of multidimensional PESs in cases where analytical electronic structure Hessians are too expensive or unavailable, and it provides new opportunities to employ high-level electronic structure calculations for dynamics at an affordable cost.
Bilayer metal oxide gate insulators for scaled Ge-channel metal-oxide-semiconductor devices
Authors: Swaminathan Shankar , Shandalov Michael , Oshima Yasuhiro , McIntyre Paul C.
Published: February 2010

We investigate the electrical properties of germanium-channel metal-oxide-semiconductor capacitors with an amorphous atomic-layer-deposited (ALD)-Al2O3 interlayer (IL) and higher-k ALD-TiO2 gate dielectric. An ALD-Al2O3 IL of ∼1 nm thickness reduces the gate leakage current density at the otherwise low band-offset TiO2/Ge interface by six orders of magnitude at flatband. Devices with the thinnest Al2O3 IL exhibited a low capacitance equivalent thickness of 1.2 nm. The hysteresis of the capacitance-voltage curves was <10 mV for TiO2/Al2O3/Ge capacitors with different Al2O3 thicknesses. We obtained a relatively low minimum density of interface states, Dit ∼3×1011 cm−2 eV−1, suggesting the potential of Al2O3 ILs for higher-k/Ge interface passivation.
The HOOH UV spectrum: Importance of the transition dipole moment and torsional motion from semiclassical calculations on an ab initio potential energy surface
Authors: Drozd Greg T. , Melnichuk Ann , Donahue Neil M.
Published: February 2010

The absorption cross section of HOOH, a starting point for larger ROOH, was calculated using the “Wigner method.” Calculations use the Wigner transform of ground state wave functions and classical approximations for excited state wave functions. Potential energy and transition dipole moment surfaces were calculated using the equation-of-motion coupled-cluster singles and doubles method over an extended Franck–Condon region. The first two O–O stretches and the first five HOOH torsional levels are included. This study also addresses two fundamental questions about ROOH photodissociation. The long wavelength Ã1A:B̃1B excited state preference has been measured from dynamics experiments, but a Franck–Condon overlap explanation has not been directly verified. A moderate barrier to HOOH torsional motion and excited state dynamics affect the temperature dependence in the UV spectrum. Based on these initial findings for HOOH, photodissociation of large ROOH cannot be eliminated as an important factor for ozone and particulate matter production seen in both ambient and laboratory studies.
Magnetic properties of nonmetal atoms absorbed MoS2 monolayers
Authors: He Jiangang , Wu Kechen , Sa Rongjian , Li Qiaohong , Wei Yongqin
Published: February 2010

The geometries, electronic structures, and magnetic properties of H-, B-, C-, N-, O-, and F-absorbed MoS2 monolayers have been investigated by first-principles calculations. The results demonstrate that all these atoms can chemically absorb on MoS2 monolayer. The total magnetic moments of H-, B-, C-, N-, and F-absorbed MoS2 monolayers are 1.0, 1.0, 2.0, 1.0, and 1.0 μB, respectively. The large spatial extensions of spin density and long-range antiferromagnetic coupling were observed in H- and F-absorbed MoS2 monolayers. Additionally, the n-type and p-type two-dimensional MoS2 semiconductors can be realized by absorbing H and N atoms, respectively.
Production of highly charged heavy ions by 18 GHz superconducting electron cyclotron resonance at Research Center for Nuclear Physics
Authors: Yorita Tetsuhiko , Hatanaka Kichiji , Fukuda Mitsuhiro , Kibayashi Mitsuru , Morinobu Shunpei , Okamura Hiroyuki , Tamii Atsushi
Published: February 2010

An 18 GHz superconducting electron cyclotron resonance ion source has been installed as a subject of the azimuthally varying field cyclotron upgrade project (K. Hatanaka et al., in Proceedings of the 17th International Conference on Cyclotrons and Their Applications, Tokyo, Japan, 18–22 October 2004, pp. 115–117), in order to increase beam currents and to extend the variety of ions. The production development of several ions has been performed since 2006 and some of them have already been used for user experiments [T. Yorita et al., Rev. Sci. Instrum. 79, 02A311 (2008)]. Further optimizations for each component such as the material of plasma electrode, material, and shape of bias probe and mirror field have been continued and more intense ion beams have been obtained for O, N, and Ar. For the purpose of obtaining highly charged Xe with several microamperes, the optimization of position and shape of plasma electrode and bias disk has also been done and highly charged Xe32+ beam has been obtained successfully.
Valence ionized states of iron pentacarbonyl and η5-cyclopentadienyl cobalt dicarbonyl studied by symmetry-adapted cluster-configuration interaction calculation and collision-energy resolved Penning ionization electron spectroscopy
Authors: Fukuda Ryoichi , Ehara Masahiro , Nakatsuji Hiroshi , Kishimoto Naoki , Ohno Koichi
Published: February 2010

Valence ionized states of iron pentacarbonyl Fe(CO)5 and η5-cyclopentadienyl cobalt dicarbonyl Co(η5-C5H5)(CO)2 have been studied by ultraviolet photoelectron spectroscopy, two-dimensional Penning ionization electron spectroscopy (2D-PIES), and symmetry-adapted cluster-configuration interaction calculations. Theory provided reliable assignments for the complex ionization spectra of these molecules, which have metal-carbonyl bonds. Theoretical ionization energies agreed well with experimental observations and the calculated wave functions could explain the relative intensities of PIES spectra. The collision-energy dependence of partial ionization cross sections (CEDPICS) was obtained by 2D-PIES. To interpret these CEDPICS, the interaction potentials between the molecules and a Li atom were examined in several coordinates by calculations. The relation between the slope of the CEDPICS and the electronic structure of the ionized states, such as molecular symmetry and the spatial distribution of ionizing orbitals, was analyzed. In Fe(CO)5, an attractive interaction was obtained for the equatorial CO, while the interaction for the axial CO direction was repulsive. For Co(η5-C5H5)(CO)2, the interaction potential in the direction of both Co–C–O and Co–Cp ring was attractive. These anisotropic interactions and ionizing orbital distributions consistently explain the relative slopes of the CEDPICS.
Low-voltage nanodomain writing in He-implanted lithium niobate crystals
Authors: Lilienblum M. , Ofan A. , Hoffmann Á. , Gaathon O. , Vanamurthy L. , Bakhru S. , Bakhru H. , Osgood R. M. , Soergel E.
Published: February 2010

A scanning force microscope tip is used to write ferroelectric domains in He-implanted single-crystal lithium niobate and subsequently probe them by piezoresponse force microscopy. Investigation of cross-sections of the samples showed that the buried implanted layer, ∼1 μm below the surface, is nonferroelectric and can thus act as a barrier to domain growth. This barrier enabled stable surface domains of <1 μm size to be written in 500 μm thick crystal substrates with voltage pulses of only 10 V applied to the tip.
Phase separation and Si nanocrystal formation in bulk SiO studied by x-ray scattering
Authors: Feroughi O. M. , Sternemann C. , Sahle Ch. J. , Schroer M. A. , Sternemann H. , Conrad H. , Hohl A. , Seidler G. T. , Bradley J. , Fister T. T. , Balasubramanian M. , Sakko A. , Pirkkalainen K. , Hämäläinen K. , Tolan M.
Published: February 2010

We present an x-ray scattering study of the temperature-induced phase separation and Si nanocrystal formation in bulk amorphous SiOx with x≈1. X-ray Raman scattering at the Si LII,III-edge reveals a significant contribution of suboxides present in native amorphous SiO. The suboxide contribution decreases with increasing annealing temperature between 800–1200 °C pointing toward a phase separation of SiO into Si and SiO2 domains. In combination with x-ray diffraction and small angle x-ray scattering the SiO microstructure is found to be dominated by internal suboxide interfaces in the native state. For higher annealing temperatures above 900 °C growth of Si nanocrystals with rough surfaces embedded in a silicon oxide matrix can be observed.
Piezoelectric energy harvesting using shear mode 0.71Pb(Mg1/3Nb2/3)O3–0.29PbTiO3 single crystal cantilever
Authors: Ren Bo , Or Siu Wing , Zhang Yaoyao , Zhang Qinhui , Li Xiaobing , Jiao Jie , Wang Wei , Liu Da’an , Zhao Xiangyong , Luo Haosu
Published: February 2010

In this letter we presented a cantilever beam used for vibration energy harvesting based on shear mode 0.71Pb(Mg1/3Nb2/3)O3–0.29PbTiO3 single crystal. The working principle of the device was inferred and the factors influencing the output were obtained using an analytical method. The electrical properties under different conditions were studied systematically. Under a cyclic force of 0.05 N (peak value), a peak voltage of 91.23 V, maximum power of 4.16 mW were measured at 60 Hz with a proof mass of 0.5 g. The results demonstrate the potential of the device in energy harvesting applied to low-power portable electronics and wireless sensors.
Hydrogen in InN: A ubiquitous phenomenon in molecular beam epitaxy grown material
Authors: Darakchieva V. , Lorenz K. , Barradas N. P. , Alves E. , Monemar B. , Schubert M. , Franco N. , Hsiao C. L. , Chen L. C. , Schaff W. J. , Tu L. W. , Yamaguchi T. , Nanishi Y.
Published: February 2010

We study the unintentional H impurities in relation to the free electron properties of state-of-the-art InN films grown by molecular beam epitaxy (MBE). Enhanced concentrations of H are revealed in the near surface regions of the films, indicating postgrowth surface contamination by H. The near surface hydrogen could not be removed upon thermal annealing and may have significant implications for the surface and bulk free electron properties of InN. The bulk free electron concentrations were found to scale with the bulk H concentrations while no distinct correlation with dislocation density could be inferred, indicating a major role of hydrogen for the unintentional conductivity in MBE InN.
Fabrication of silicon nanobump arrays by near-field enhanced laser irradiation
Authors: Wang X. C. , Zheng H. Y. , Tan C. W. , Wang F. , Yu H. Y. , Pey K. L.
Published: February 2010

A simple approach to fabricate two-dimensional nanobump arrays on silicon (Si) substrate is reported. In the process, a single 248 nm excimer laser pulse was applied on a self-assembled monolayer of 1.5-μm-diameter silica microspheres on a n-doped (100) Si wafer. After laser irradiation at a fluence of 300 mJ/cm2, a regular array of conical Si nanobumps surrounded by a ring shaped trench were fabricated. The structure of the nanobump arrays was characterized by scanning electron microscope, and atomic force microscope. The formed nanobumps were determined to be Si-based bumps with energy disperse spectroscopy. The mechanisms involved in the formation of nanobumps were discussed.
Tuning superconductivity by carrier injection
Authors: Koval Yuri , Jin Xiaoyue , Bergmann Christoph , Simsek Yilmaz , Özyüzer Lütfi , Müller Paul , Wang Huabing , Behr Günter , Büchner Bernd
Published: February 2010

We have found that by extensive current injection along the c-axis, the superconducting properties of Bi2Sr2CaCu2O8+δ can be changed effectively. We show that critical temperature, c-axis resistivity, and critical current of intrinsic Josephson junctions can be tuned in a large range from underdoping to extreme overdoping. This effect is reversible and persistent. Our results can be explained by trapping charges in the insulating layers, which induce a change of carrier concentration in superconducting planes. This floating gate concept can be a general property of layered materials where the insulating charge reservoir layers are separated from the conducting planes.