bluuebunny/crossref_metadata_2025 huggingface dataset:
Different profiles of hepatic alkoxyresorufin O‐dealkylase activities in small rodents
Authors: Chatuphonprasert Waranya , Rermraksakul Papimon , Udomsuk Latiporn , Lao‐ong Thinnakorn , Jarukamjorn Kanokwan
Published: May 2012

The aims of the present study were to determine cytochrome P450 enzyme activity in six strains of experimental rodents (n = 5/sex/species): ICR, C57BL/6 and DBA/2 mice; Sprague Dawley and Wistar rats; and Dunkin Hartley guinea pigs. After animals were treated with the typical inducers β‐naphthoflavone (BNF), dexamethasone (DEX) and phenobarbital (PB), the levels of O‐dealkylation of ethoxyresorufin (EROD), methoxyresorufin (MROD), pentoxyresorufin (PROD) and benzyloxyresorufin (BROD) activity were determined using responsive catalytic reactions to study CYP1A1, CYP1A2 and CYP2B, respectively. A maximal induction of EROD and MROD was found in BNF‐treated animals from all strains (2.4‐ to 15.1‐fold) except DBA/2 (0.9‐ to 1.8‐fold). C57BL/6 mice had the strongest BNF‐induced EROD (15.1‐fold) and MROD (8.3‐fold) activities. No differences in BNF‐induced EROD and MROD activities were observed between males and females. However, the EROD activity of Wistar rats and the MROD activity of Sprague Dawley rats were higher in males than females. DEX induced PROD activity only in mice (1.3‐ to 7.1‐fold), but not in rats and guinea pigs (0.2‐ to 1.1‐fold). However, induction of BROD activity was found in DEX‐treated mice and rats (1.5 to 12.5‐fold), but not in guinea pigs (0.3 to 0.4‐fold). PB caused a significant elevation of PROD (1.7‐ to 10.4‐fold) and BROD (31‐ to 13.2‐fold) activities in all the animals. PB‐induced BROD activity was higher in females than males in Sprague Dawley rats. These observations strongly suggest that the choice of experimental animal strain, species and inducer is of critical importance for studies of drug metabolism and interaction. Copyright © 2012 John Wiley & Sons, Ltd.
Usefulness of administration of non‐organophosphate cholinesterase inhibitors before acute exposure to organophosphates: assessment using paraoxon
Authors: Petroianu Georg A. , Nurulain Syed M. , Shafiullah Mohamed , Hasan Mohamed Y. , Kuča Kamil , Lorke Dietrich E.
Published: May 2012

Reversible acetylcholinesterase (AChE) inhibitors can protect against the lethal effects of irreversible organophosphorus AChE inhibitors (OPCs), when administered before OPC exposure. We have assessed in vivo the mortality‐reducing efficacy of a group of known AChE inhibitors, when given in equitoxic dosage before exposure to the OPC paraoxon. Protection was quantified in rats by determining the relative risk (RR) of death.

Best in vivo protection from paraoxon‐induced mortality was observed after prophylactic administration of physostigmine (RR = 0.30) or the oxime K‐27 (RR = 0.34); both treatments were significantly superior to the pre‐treatment with all other tested compounds, including the established substance pyridostigmine. Tacrine (RR = 0.67), ranitidine (RR = 0.72), pyridostigmine (RR = 0.76), tiapride (RR = 0.80) and 7‐MEOTA (RR = 0.86) also significantly reduced the relative risk of paraoxon‐induced death, but to a lesser degree. Methylene blue, amiloride and metoclopramide had an unfavorable effect (RR ≥ 1), significantly increasing mortality. When CNS penetration by prophylactic is undesirable K‐27 is a promising alternative to pyridostigmine. Copyright © 2012 John Wiley & Sons, Ltd.
In vivo protective effect of Copaifera langsdorffii hydroalcoholic extract on micronuclei induction by doxorubicin
Authors: Alves Jacqueline Morais , Munari Carla Carolina , de Azevedo Bentes Monteiro Neto Moacir , Furtado Ricardo Andrade , Senedese Juliana Marques , Bastos Jairo Kenupp , Tavares Denise Crispim
Published: May 2012

Copaifera lansdorffii Desf. is known as ‘copaíba’, ‘copaiva’ or ‘paú‐de‐óleo’, and is found in part of Brazil. The present study was undertaken to evaluate the genotoxic potential of C. langsdorffii leaf hydroalcoholic extract (CLE) and its influence on the genotoxicity induced by the chemotherapeutic agent doxorubicin (DXR) using the Swiss mouse peripheral blood micronucleus test. HPLC analysis of CLE using two monolithic columns linked in series allowed quantification of two major flavonoid heterosides, quercitrin and afzelin. Animals were treated with CLE by gavage at doses of 10, 20, 40 and 80 mg kg−1 body weight per day, each for 20 days. Peripheral blood samples were collected at 24 and 48 h, and 7, 15 and 21 days after the beginning of the treatment. For the antigenotoxicity evaluation, the animals treated with different concentrations of CLE received DXR (15 mg kg−1 body weight, intraperitoneal) at day 20. The peripheral blood samples were collected 24 and 48 h after the treatment with DXR. The results demonstrated that CLE itself was not genotoxic in the mouse micronucleus assay. In animals treated with CLE and DXR, the number of micronucleus was significantly decreased compared with animals receiving DXR alone. The putative antioxidant activity of one or more of the active compounds of CLE may explain the effect of this plant on DXR genotoxicity. Copyright © 2012 John Wiley & Sons, Ltd.
Hoechst increases adeno‐associated virus‐mediated transgene expression in airway epithelia by inducing the cytomegalovirus promoter
Authors: Dickey David D. , Excoffon Katherine J. D. A. , Young Krista R. , Parekh Kalpaj R. , Zabner Joseph
Published: May 2012

Background

In airway epithelia, the kinetics of recombinant adeno‐associated virus (AAV) transgene expression is slow. This has negative practical implications for research, as well as for translation into therapy. The DNA minor groove‐binding agent Hoechst‐33342 has been shown to enhance AAV transgene expression. In the present study, we investigated the mechanism of Hoechst‐related augmentation of AAV‐mediated transgene expression.

Methods

We investigated the effect of Hoechst‐33342 on HT1080, COS‐7, mouse and human airway epithelia transduced with different AAV serotypes encoding enhanced green fluorescent protein (eGFP). We exposed cells to increasing concentrations of Hoechst‐33342 at different time points. We evaluated the effect on second‐strand DNA synthesis using AAV with a self‐complementary genome. We also investigated the effect on expression from transfected plasmids with and without AAV2 inverted terminal repeats (ITRs).

Results

We found that Hoechst‐33342 significantly accelerated AAV transgene expression for all serotypes tested. Hoechst‐33342 only had an effect when the treatment was given during or after transduction, even 120 days post‐transduction, suggesting an effect on transgene expression regulation. Hoechst‐33342 increased transgene expression when cells were transduced with a self‐complementary AAV with the cytomegalovirus promoter, although there was no effect on cells transduced with conventional single‐stranded AAV encoding the Rous sarcoma virus promoter. Finally, Hoechst‐33342 increases gene expression from transfected plasmids regardless of the presence of AAV2 ITRs.

Conclusions

Hoechst dramatically augments and accelerates AAV‐mediated transgene expression in airway epithelia without altering AAV‐mediated gene transfer. Hoechst activation of the cytomegalovirus promoter is seen in plasmids, although it is drastically enhanced in the context of AAV. Copyright © 2012 John Wiley & Sons, Ltd.
Γ‐convergence: a tool to investigate physical phenomena across scales
Authors: Focardi Matteo
Published: May 2012

De Giorgi's Γ‐convergence is a variational theory modelled upon the convergence of families of (perturbed) minimum problems and of the corresponding minimizers.

In these notes, after reviewing briefly the basic theory and accounting for some recent new insights, we discuss three examples of static mechanical models, which can be analysed by means of Γ‐convergence arguments. Copyright © 2012 John Wiley & Sons, Ltd.
Simple linear flow decomposition algorithms on trees, circles, and augmented trees
Authors: Vaidyanathan Balachandran
Published: May 2012

The flow decomposition algorithm transforms an arc flow‐based solution to a network flow problem into flows on directed paths and cycles. When the undirected graph induced by arcs with positive flow is a tree, a circle, or an augmented tree (with n nodes), the standard implementation of the algorithm runs in O (n2) time. In this article, we exploit the structure of the network to develop an O (n) flow decomposition algorithm. The run‐time relies on the property that for these networks, paths or cycles can be represented implicitly in O (1) space. The algorithm is easy to implement and does not use complicated data structures. Because the size of the input is O (n), our algorithm is the fastest possible for flow decomposition on these special networks. Our algorithm can be used to improve run‐times for solving matching and transportation problems on trees and circles. © 2012 Wiley Periodicals, Inc. NETWORKS, 2012
Robust mean absolute deviation problems on networks with linear vertex weights
Authors: López‐de‐los‐Mozos M.C. , Puerto J. , Rodríguez‐Chía A.M.
Published: May 2012

This article deals with incorporating the mean absolute deviation objective function in several robust single facility location models on networks with dynamic evolution of node weights, which are modeled by means of linear functions of a parameter. Specifically, we have considered two robustness criteria applied to the mean absolute deviation problem: the MinMax criterion, and the MinMax regret criterion. For solving the corresponding optimization problems, exact algorithms have been proposed and their complexities have been also analyzed. © 2012 Wiley Periodicals, Inc. NETWORKS, 2013
Can students run their own interventions?: A self‐administered math fluency intervention
Authors: Hulac David M. , Dejong Kayla , Benson Nicholas
Published: May 2012

Manipulating the ratio of known to unknown items has been shown to improve student on‐task behavior and increase the desirability of schoolwork. Although many intervention protocols manipulate ratios of known to unknown items, these frequently require extensive adult cuing. School psychologists recommending such interventions may face resistance from teachers who find the work to be too time intensive. Self‐administered interventions whereby the students act as primary interventionists may alleviate this concern. A modified multiple baseline design across a group of 11 students identified by their teachers as having difficulty mastering multiplication facts was used to evaluate a self‐administered folding‐in technique. As hypothesized, for the overall sample, stronger effects were observed on math curriculum‐based measures (CBM) than on a control reading task (Maze CBM). Individually, 7 of the 11 students demonstrated higher levels of growth during the intervention phase than during the baseline phase. No student demonstrated higher Maze CBM growth rates during the intervention phase relative to the baseline phase. In contrast, of the 4 students for whom a link between the intervention and the baseline could not be established, 3 demonstrated higher levels of performance on math CBMs following the intervention phase. Results are discussed in light of a response‐to‐intervention model. © 2012 Wiley Periodicals, Inc.
From Principles to Practice: Collegial Observation for Teacher Development
Authors: Gray Susan M.
Published: May 2012

Teachers constantly question their own practice. Often, their questions remain unexplored. Collegial observation provides one way to see teaching differently and understand the tensions involved in incorporating new theoretical understandings into practice. Gebhard (1999) argues that conversations preceding and following such observations are critical triggers for teacher development. The questions, conversations, and observations that are the focus of this article occurred within a larger case study with teachers who taught culturally and linguistically diverse classes comprising students who were native English speakers as well as students who spoke English as an additional language. Pairs of secondary content teachers (social studies, science, and mathematics) planned, implemented, and evaluated lesson sequences with a language focus in their content area. Each pair chose one principle from language learning research to guide the design of their sequence. This article investigates the mathematics pair's use of collegial observation to explore ways of incorporating opportunities for student interaction, particularly for English language learners, in their lesson sequence. Findings suggest that such observations and conversations contribute to understanding the tensions in questioning, seeing, reimagining, and reshaping practice. What makes this observation so unusual is that New Zealand secondary schools lack a systemic collegial culture.
Extended Nonfiction Readers for EAP Programs
Authors: Fitzsimmons‐Doolan Shannon , Davis Jessica , Stoller Fredricka L. , Crawford William
Published: May 2012

Content‐based instruction course designers have many important decisions to make when developing courses for postsecondary English for academic purposes (EAP) students. One important consideration revolves around deciding if students would benefit most from the use of sustained content (Murphy & Stoller, 2001) or a topical approach (Brinton, Snow, & Wesche, 2003). The authors advocate the sustained content approach and promote the use of extended nonfiction readers, specifically those designed for students in Grades 7–12, as primary texts for achieving course goals for intermediate‐level EAP students. The authors support this stance by (a) establishing a strong case for the adoption of extended nonfiction readers in sustained content instruction, (b) introducing helpful text selection criteria, (c) describing scaffolding techniques and synthesis tasks to be used with such readers, and (d) offering tips that can assist teachers and administrators in making a programmatic transition to this pedagogical approach. For practitioners at other grade levels or in programs that endorse other content‐based approaches, many of the ideas presented here are relevant with modest adaptations.
Differentiated Instruction in an Elementary School EFL Classroom
Authors: Chien Chin‐Wen
Published: May 2012

Elementary school English teachers in Taiwan face classes of students with differing levels of English proficiency, to the point where about one‐third of the students may have never learned English before, and another third may already have read Harry Potter in English. A successful teacher recognizes that diversity may affect learning and works toward a classroom in which diversity is valued (Tileston, 2004). Differentiated instruction is one way to meet the needs of diverse students (Thousand, Villa, & Nevin, 2007). This article focuses on how Tomlinson's (1999) three components of differentiated instruction can be implemented in an elementary school EFL classroom.
Fluoride decreased osteoclastic bone resorption through the inhibition of NFATc1 gene expression
Authors: Pei Junrui , Li Bingyun , Gao Yanhui , Wei Yudan , Zhou Lingwang , Yao Hongju , Wang Jing , Sun Dianjun
Published: May 2012

Over the past two decades, fluoride effects on osteoclasts have been evaluated; however, its molecular mechanisms remain unclear. In this study, we investigated the effect of fluoride on osteoclast formation, function, and regulation using osteoclasts formed from mice bone marrow macrophages treated with the receptor activator of NF‐κB ligand and macrophage colony‐stimulating factor. Our data showed that fluoride levels ≤ 8 mg/L had no effect on osteoclast formation; however, it significantly reduced osteoclast resorption at 0.5 mg/L. Fluoride activity on bone resorption occurred through the inhibition of nuclear factor of active T cells (NFAT) c1 expression. Furthermore, the expression of its downstream genes, including the dendritic cell‐specific transmembrane protein, c‐Src, the d2 isoform of vacuolar (H+) ATPase v0 domain, matrix metalloproteinase 9, and cathepsin K were decreased, leading to impaired osteoclast acidification, reduced secretion of proteolytic enzymes, and decreased bone resorption. In summary, our results suggested that fluoride has different roles in osteoclast formation and function. Fluoride ≤ 8 mg/L did not impact osteoclast formation; however, it significantly decreased the resorption activity of newly formed osteoclasts. The molecular mechanism of fluoride action may involve inhibition of NFATc1 and its downstream genes. © 2012 Wiley Periodicals, Inc. Environ Toxicol 29: 588–595, 2014.
Perinatal exposure to di‐(2‐ethylhexyl)‐phthalate leads to cognitive dysfunction and phospho‐tau level increase in aged rats
Authors: Sun Wei , Ban Jin‐Bao , Zhang Ni , Zu Yu‐Kun , Sun Wen‐Xiao
Published: May 2012

Di‐(2‐ethylhexyl)‐Phthalate (DEHP) can affect glucose and insulin homeostasis in periphery and lead to insulin resistance, especially exposure of DEHP during critical developmental period. Given the potential relationship between insulin resistance and pathogenesis of Alzheimer's disease (AD) in elderly life, we investigated the relationship between perinatal DEHP exposure and AD pathogenesis. Our results suggested that perinatal exposure to DEHP can affect the expression of insulin and insulin‐Akt‐ GSK‐3β signal pathway in hippocampus. Furthermore, impaired cognitive ability and increased level of phospho‐Tau was observed in DEHP‐exposed rat offspring (1.25 ± 0.11 vs. 0.47 ± 0.07, P < 0.05). The present study demonstrates that perinatal exposure to DEHP may be a potential risk factor for AD pathogenesis associated with insulin resistance and insulin metabolism disorder in the hippocampus. © 2012 Wiley Periodicals, Inc. Environ Toxicol 29: 596–603, 2014.
Overall Distribution of Trauma‐related Deaths in Berlin 2010: Advancement or Stagnation of German Trauma Management?
Authors: Kleber Christian , Giesecke Moritz T. , Tsokos Michael , Haas Norbert P. , Schaser Klaus D. , Stefan Poloczek , Buschmann Claas T.
Published: May 2012

Background

Trauma is the leading cause of death among children, adolescents, and young adults. The latest data from the German Trauma Registry reveals a constant decrease in trauma mortality, indicating that 11.6 % of all trauma patients in 2010 died in hospital. Notably, trauma casualties dying before admission to hospital have not been systematically surveyed and analyzed in Germany.

Methods

We conducted a prospective observational study of all traumatic deaths in Berlin, recording demographic data, trauma mechanisms, and causes/localization and time of death after trauma. Inclusion criteria were all deaths following trauma from 1 January 2010 to 31 December 2010.

Results

A total of 440 trauma fatalities were included in this study, with a mortality rate of 13/100,000 inhabitants; 78.6 % were blunt injuries, and fall from a height >3 m (32.7 %) was the leading trauma mechanism. 32.5 % died immediately, 23.9 % died within 60 min, 7.7 % died within 1–4 h, 16.8 % died within 4–48 h, 11.1 % died <1 week later, and 8 % died >1 week after trauma. The predominant causes of death were polytrauma (45.7 %), sTBI (38 %), exsanguination (9.5 %), and thoracic trauma (3.2 %). Death occurred on‐scene in 58.7 % of these cases, in the intensive care unit in 33.2 %, and in 2.7 % of the cases, in the emergency department, the operating room, and the ward, respectively.

Conclusions

Polytrauma is the leading cause of death, followed by severe traumatic brain injury (sTBI). The temporal analysis of traumatic death indicates a shift from the classic “trimodal” distribution to a new “bimodal” distribution. Besides advances in road safety, prevention programs and improvement in trauma management—especially the pre‐hospital phase—have the potential to significantly improve the survival rate after trauma.
Severity of Complications After Gastrectomy in Elderly Patients With Gastric Cancer
Authors: Hayashi Tsutomu , Yoshikawa Takaki , Aoyama Toru , Ogata Takashi , Cho Haruhiko , Tsuburaya Akira
Published: May 2012

Background

The risk of surgery for gastric cancer has not been fully evaluated, and this study aimed to assess the severity of postoperative complications after D2 or modified D2 gastrectomy in elderly patients.

Methods

Eligible patients were retrospectively selected from the Kanagawa Cancer Center database between 1990 and 2009 based on the following criteria: age ≥80 years and D2 or modified D2 gastrectomy as a primary treatment for gastric cancer. The severity of complications was evaluated using the Clavien–Dindo classification.

Results

A total of 83 patients with a median age of 82 years (range 80–88 years) were entered in this study. Sixty (72 %) had at least one co‐morbid condition. American Society of Anesthesiologists scores were 2 in 66 patients and 3 in 17 patients. The extent of gastrectomy was distal in 65 (78 %) and total in 18 (22 %) patients. The procedure used for lymphadenectomy was modified D2 in 38 (46 %) and D2 in 45 (54 %) patients. Altogether, 18 complications were observed in 15 patients. The overall morbidity rate was 18 % [95 % confidence interval (CI) 9.7–26.2 %], and the mortality rate was 3.6 % (95 % CI 0–7.6 %). Complications were classified as grade 2 (n = 9), grade 3a (n = 1), grade 3b (n = 4), grade 4 (n = 1), and grade 5 (n = 3). Severe complications (≥ grade 3) occurred in 8.4 % (95 % CI 2.4–14.4 %).

Conclusions

The morbidity rate was acceptable, but that of severe complications was high, suggesting that surgery for gastric cancer in elderly patients is risky and should be limited.
Chemical and Sensory Stability of Fried‐Salted Soybeans Prepared in Different Vegetable Oils
Authors: Jáuregui María P. , Riveros Cecilia , Nepote Valeria , Grosso Nelson R. , Gayol María F.
Published: May 2012

The purpose of this work was to evaluate the stability of fried‐salted soybeans prepared in normal and high‐oleic sunflower and normal peanut oils. Three products were obtained: fried‐salted soybeans prepared in sunflower oil (FSS), in high‐oleic sunflower oil (FSH) and in peanut oil (FSP). Products were stored for 112 days at 22 and 40 °C. Samples were removed from storage for chemical and sensory descriptive analyses. Fatty acid composition of raw soybeans changed after the frying process. Palmitic, linoleic, linolenic acids, iodine value and saturated/unsaturated ratio decreased while oleic acid and the oleic/linoleic ratio (O/L) increased after the frying process of soybeans. Soybeans fried in FSH had the highest O/L (2.42), followed by FSP (1.07), FSS (0.52), and finally by raw soybeans (0.37). Peroxide values higher than 10 mequiv O2 kg−1 were reached after 23 days in FSS, 223 days in FSH, and 159 days in FSP at 22 °C. The shelf life was 10 (at 22 °C) and 7 (at 40 °C) times longer in FSH than in FSS. Soybeans fried in high‐oleic sunflower and peanut oils had a higher stability than soybeans fried in sunflower oil, making them more resistant to lipid oxidation and the development of rancid flavors.
Structural Controls on Coal Fire Distributions – Remote Sensing Based Investigation in the Raniganj Coalfield, West Bengal
Authors: Guha Arindam , Kumar K. Vinod
Published: May 2012

Coal fires are serious problem in Raniganj coalfield as it is the case for some of the other coalfields of India like Jharia coalfield. Earlier efforts were made to map the coal fires of this coal-field based on satellite observation. But the restricted distribution of major coal fires in the particular portion of the coalfield makes the basis for finding the geological control if responsible for coal fire distribution. In present study, night time thermal data of ASTER (Advance spaceborne thermal emission and reflection radiometer) is used to map the latest distribution (December, 2006) of coal fires in the Raniganj coalfield. Coal fire map shows that most significant zone affected by fire is at the north-western portion of the coalfield; where NE- trending open cast mines are affected by fire. This fire zone is associated with high grade coal of the Barakar Formation. Coal fires are also mapped in open cast pits of Jambad-Mangalpur area occurring over rocks of the Raniganj Formation. By integrating geological map and satellite-derived coal fire map of Raniganj coal field, it is observed that the coal fires detected by remote sensing study are spatially associated with intraformational faults. These faults may have played significant role in supplying oxygen to these coal-fires and allowing them to propagate down the depth along the trends of the faults.
Interface mediated resistive switching in epitaxial NiO nanostructures
Authors: Sullaphen Jivika , Bogle Kashinath , Cheng Xuan , Gregg John M. , Valanoor Nagarajan
Published: May 2012

We report on the non-volatile resistive switching properties of epitaxial nickel oxide (NiO) nanostructures, 10-100 nm wide and up to 30 nm high grown on (001)-Nb:SrTiO3 substrates. Conducting-atomic force microscopy on individual nano-islands confirms prominent bipolar switching with a maximum ON/OFF ratio of ∼103 at a read voltage of ∼+0.4 V. This ratio is found to decrease with increasing height of the nanostructure. Linear fittings of I-V loops reveal that low and high resistance states follow Ohmic-conduction and Schottky-emission mechanism, respectively. The switching behavior (dependence on height) is attributed to the modulation of the carrier density at the nanostructure-substrate interface due to the applied electric field.
Resolved E-symmetry zone-centre phonons in LiTaO3 and LiNbO3
Authors: Margueron S. , Bartasyte A. , Glazer A. M. , Simon E. , Hlinka J. , Gregora I. , Gleize J.
Published: May 2012

E-symmetry optical phonons at the Γ point of LiNbO3 and LiTaO3 were experimentally resolved in spectra measured by infrared and Raman spectroscopy. For this purpose, congruent and nearly stoichiometric crystals of LiNbO3 and LiTaO3, and mixed LiNb1−xTaxO3, crystals were studied. The results show that some of the E modes have weak intensities in Raman or infrared spectra. Thus the complete assignment of E-symmetry modes has been achieved by comparing Raman and infrared data. In addition, this assignment has been confirmed by Raman measurements at low temperatures.
Tunable strain effect and ferroelectric field effect on the electronic transport properties of La0.5Sr0.5CoO3 thin films
Authors: Zhu Q. X. , Wang W. , Zhao X. Q. , Li X. M. , Wang Y. , Luo H. S. , Chan H. L. W. , Zheng R. K.
Published: May 2012

Tensiled La0.5Sr0.5CoO3 (LSCO) thin films were epitaxially grown on piezoelectric 0.67Pb (Mg1/3Nb2/3)O3-0.33PbTiO3 (PMN-PT) single-crystal substrates. Due to the epitaxial nature of the interface, the lattice strain induced by ferroelectric poling or the converse piezoelectric effect in the PMN-PT substrate is effectively transferred to the LSCO film and thus reduces the tensile strain of the film, giving rise to a decrease in the resistivity of the LSCO film. We discuss these strain effects within the framework of the spin state transition of Co3+ ions and modification of the electronic bandwidth that is relevant to the induced strain. By simultaneously measuring the strain and the resistivity, quantitative relationship between the resistivity and the strain was established for the LSCO film. Both theoretical calculation and experimental results demonstrate that the ferroelectric field effect at room temperature in the LSCO/PMN-PT field-effect transistor is minor and could be neglected. Nevertheless, with decreasing temperature, the ferroelectric field effect competes with the strain effect and plays a more and more important role in influencing the electronic transport properties of the LSCO film, which we interpreted as due to the localization of charge carriers at low temperature.
Phenomenological description of depoling current in Pb0.99Nb0.02(Zr0.95Ti0.05)0.98O3 ferroelectric ceramics under shock wave compression: Relaxation model
Authors: Jiang Dongdong , Du Jinmei , Gu Yan , Feng Yujun
Published: May 2012

By assuming a relaxation process for depolarization associated with the ferroelectric (FE) to antiferroelectric (AFE) phase transition in Pb0.99Nb0.02(Zr0.95Ti0.05)0.98O3 ferroelectric ceramics under shock wave compression, we build a new model for the depoling current, which is different from both the traditional constant current source (CCS) model and the phase transition kinetics (PTK) model. The characteristic relaxation time and new-equilibrated polarization are dependent on both the shock pressure and electric field. After incorporating a Maxwell s equation, the relaxation model developed applies to all the depoling currents under short-circuit condition and high-impedance condition. Influences of shock pressure, load resistance, dielectric property, and electrical conductivity on the depoling current are also discussed. The relaxation model gives a good description about the suppressing effect of the self-generated electric field on the FE-to-AFE phase transition at low shock pressures, which cannot be described by the traditional models. After incorporating a time- and electric-field-dependent repolarization, this model predicts that the high-impedance current eventually becomes higher than the short-circuit current, which is consistent with the experimental results in the literature. Finally, we make the comparison between our relaxation model and the traditional CCS model and PTK model.
Phononic and structural response to strain in wurtzite-gallium nitride nanowires
Authors: Loh G. C. , Teo E. H. T. , Tay B. K.
Published: May 2012

Gallium nitride (GaN) nanowires exist in a myriad of cross-sectional shapes. In this study, a series of classical molecular dynamics simulations is performed to investigate the strain-phononics-structure relationship in rectangular and triangular wurtzite-GaN nanowires. The thermal conductivity of the nanowires is linearly dependent on the uniaxial strain in both compressive and tensile regimes, and shows no significant dissimilitude for the same amount of strain exerted on the two types of nanowire. This is coherent with an analytical approach using the Boltzmann transport theory. However, the thermomechanical behaviour at the vertex regions shows palpable differences between the two subfamilies, relative to the non-vertex faceted regions, as the structural morphology is most disparate at the vertices. Furthermore, the degree of strain asymmetry is a strong determinant of the vibrational response and consequently thermal conductance.
Photonic band effect in single-layers of high refractive index spheres of different compactness
Authors: Andueza A. , Morales P. , Sevilla J.
Published: May 2012

Transmission spectra from single-layers of high dielectric permittivity (ɛ = 7) glass spheres have been measured, in microwave region, for different angular incidences. The same systems have been calculated by Finite-Difference Time-Domain (FDTD) method. The dispersion diagrams of photonic bands in triangular geometries have been obtained for a number of different compactness cases. The experimental and the calculated photonic band structures show a good agreement in all the compactness values studied. They were also compared with the Mie resonances of the isolated spheres. The results indicate that the characteristics of the Mie resonances appear dominant in the photonic band structure as the compactness of the lattice decreases. Dispersion diagrams present several low dispersion photonic bands, independent of incidence-angle, with high Q-values, that could be useful for future applications of the considered structures like filters or solar cells.
Hexagonal superlattice pattern consisting of colliding filament pairs in a dielectric barrier discharge
Authors: Dong Lifang , Li Ben , Lu Ning , Li Xinchun , Shen Zhongkai
Published: May 2012

Colliding-pairs hexagonal superlattice pattern (CPHSP) is studied in a dielectric barrier discharge system. The evolution of CPHSP bifurcating from a hexagonal pattern to chaos is shown. The phase diagrams of CPHSP as a function of discharge parameters are given. From a series of pictures taken by a high speed video camera, collisions between two spots are observed and the superposition of many collisions results in each big spot presenting four small spots on long time scales. Measurements of the correlation between filaments indicate that the pattern is an interleaving of four different transient hexagonal sublattices. Depending on the discharging sequence, the forces exerted on one colliding spot are discussed briefly.
Optical switch based on electrowetting liquid lens
Authors: Li Lei , Liu Chao , Peng Hua-Rong , Wang Qiong-Hua
Published: May 2012

In this paper, we propose an optical switch based on an electrowetting liquid lens. The device consists of an electrowetting liquid lens and a non-transparent cap with a pin hole. When the lens is actuated to be positive, the incident light can be converged on the pin hole and pass through the hole with less attenuation. When the lens is deformed to be negative, the incident light is diverged and most of light is blocked by the cap. Our results show that the system can provide high contrast ratio (∼800:1) and reasonable response time (∼88 ms). The proposed optical switch has potential application in light shutters, variable optical attenuators, and adaptive irises.
Stochastic fluctuations of dust particle charge in RF discharges
Authors: Shotorban B.
Published: May 2012

In addition to RF oscillations, intrinsic stochastic fluctuations due to the discreteness of electrons and ions could be important to the charging of a dust particle in RF discharges. These fluctuations are studied in the present work for three cases [M. Bacharis et al., Plasma Sources Sci. Technol. 19, 025002 (2010)] relevant to RF discharges employing a recently proposed model [B. Shotorban, Phys. Rev. E 83, 066403 (2011)] valid for stochastic charging at nonstationary states. The cases are concerned with a time varying electron number density relevant to sheaths, a time varying electric field relevant to the bulk plasma, and a time-dependent bi-Maxwellian distribution of electrons in a low pressure discharge. Two dust particles with different sizes are individually studied in each case. The radius of one is ten times larger than the radius of the other. In all of the cases, for the larger dust particle, the root-mean-squre of charge stochastic fluctuations is about an order of magnitude smaller than the amplitude of RF charge oscillations, while for the smaller dust particle, they are comparable in magnitude.
Energy spectrum, dissipation, and spatial structures in reduced Hall magnetohydrodynamic
Authors: Martin L. N. , Dmitruk P. , Gomez D. O.
Published: May 2012

We analyze the effect of the Hall term in the magnetohydrodynamic turbulence under a strong externally supported magnetic field, seeing how this changes the energy cascade, the characteristic scales of the flow, and the dynamics of global magnitudes, with particular interest in the dissipation. Numerical simulations of freely evolving three-dimensional reduced magnetohydrodynamics are performed, for different values of the Hall parameter (the ratio of the ion skin depth to the macroscopic scale of the turbulence) controlling the impact of the Hall term. The Hall effect modifies the transfer of energy across scales, slowing down the transfer of energy from the large scales up to the Hall scale (ion skin depth) and carrying faster the energy from the Hall scale to smaller scales. The final outcome is an effective shift of the dissipation scale to larger scales but also a development of smaller scales. Current sheets (fundamental structures for energy dissipation) are affected in two ways by increasing the Hall effect, with a widening but at the same time generating an internal structure within them. In the case where the Hall term is sufficiently intense, the current sheet is fully delocalized. The effect appears to reduce impulsive effects in the flow, making it less intermittent.
On the delayed gas breakdown in a ringing theta-pinch with bias magnetic field
Authors: Meeks Warner C. , Rovey Joshua L.
Published: May 2012

A single particle model and particle-in-cell simulations are used to elucidate the breakdown physics in a ringing theta-pinch with a bias magnetic field. Previous experimental results show that gas breakdown occurs when the bias magnetic field is nullified by the theta-pinch magnetic field. The analyses presented here agree with the experimental results and show that electron kinetic energy does not exceed the ionization threshold of deuterium until the net magnetic field is approximately zero. Despite the presence of a strong electric field, the gyromotion of electrons within the bias magnetic field prevents them from gaining energy necessary to ionize the gas. Parametric analysis of the peak electron energy as a function of the bias and pre-ionization magnetic fields reveals that: (1) when the bias magnetic field is ≈97% of the pre-ionization magnetic field, peak electron energies are highly erratic resulting in poor overall ionization, and (2) full ionization with repeatable behavior requires a pre-ionization to bias magnetic field ratio of approximately 2 to 1 or higher.
Plasmonic dispersion engineering of coupled metal nanoparticle-film systems
Authors: DiMaria Jeff , Paiella Roberto
Published: May 2012

The plasmonic dispersion properties of thin silver films in close proximity of square-periodic arrays of silver nanocylinders are investigated via transmission measurements and numerical simulations. Due to their nanoscale thicknesses, these films support hybrid surface plasmon modes extended across both interfaces, whose dispersion curves exhibit a large geometrically tunable energy splitting. Furthermore, the spatial and spectral overlap between these modes and the nanoparticles’ localized plasmonic resonances produces an additional anticrossing in the dispersion spectrum. The resulting plasmonic excitations are attractive for applications given their wide tunability, coupling to free-space radiation, and ability to extend into an optically active substrate.
Optical transitions of InAs/GaAs quantum dot under annealing process
Authors: Triki M. , Jaziri S. , Bennaceur R.
Published: May 2012

A numerical method has been used for the determination of the confined eigenstates and their corresponding optical transitions in an interdiffused InAs/GaAs single quantum dot (QD). Annealing process has found to result in the change of the QD composition, morphology and hence the potential profiles. Compared with the as-grown QD, calculations presented here show blueshifter and nearer optical transition energies for the excitons in the interdiffused one. We find also that QDs retain their zero-dimensional density of states after the diffusion of the potential. The results are compared with experimental data.
An apparatus for immersing trapped ions into an ultracold gas of neutral atoms
Authors: Schmid Stefan , Härter Arne , Frisch Albert , Hoinka Sascha , Denschlag Johannes Hecker
Published: May 2012

We describe a hybrid vacuum system in which a single ion or a well-defined small number of trapped ions (in our case Ba+ or Rb+) can be immersed into a cloud of ultracold neutral atoms (in our case Rb). This apparatus allows for the study of collisions and interactions between atoms and ions in the ultracold regime. Our setup is a combination of a Bose-Einstein condensation apparatus and a linear Paul trap. The main design feature of the apparatus is to first separate the production locations for the ion and the ultracold atoms and then to bring the two species together. This scheme has advantages in terms of stability and available access to the region where the atom-ion collision experiments are carried out. The ion and the atoms are brought together using a moving one-dimensional optical lattice transport which vertically lifts the atomic sample over a distance of 30 cm from its production chamber into the center of the Paul trap in another chamber. We present techniques to detect and control the relative position between the ion and the atom cloud.
A ultra-high-vacuum wafer-fusion-bonding system
Authors: McKay Kyle , Wolter Scott , Kim Jungsang
Published: May 2012

The design of heterojunction devices is typically limited by material integration constraints and the energy band alignment. Wafer bonding can be used to integrate material pairs that cannot be epitaxially grown together due to large lattice mismatch. Control of the energy band alignment can be provided by formation of interface dipoles through control of the surface chemistry. We have developed an ultra-high-vacuum system for wafer-fusion-bonding semiconductors with in situ control and measurement of surface properties relevant to interface dipoles. A wafer-fusion-bonding chamber with annealing capabilities was integrated into an ultra-high-vacuum system with a sputtering chamber and an x-ray photoelectron spectroscopy system for preparing and measuring the surface chemistry of wafers prior to bonding. The design of the system along with initial results for the fusion-bonded InGaAs/Si heterojunction is presented.
Multiplex and simultaneous measurement of displacement and temperature using tapered fiber and fiber Bragg grating
Authors: Ji Chongke , Zhao Chun-Liu , Kang Juan , Dong Xinyong , Jin Shangzhong
Published: May 2012

A simple method to work out the multiplexing of tapered fiber based sensors is proposed and demonstrated. By cascading a tapered fiber with a fiber Bragg grating (FBG), the sensor head is provided with a wavelength identification, different FBGs provide the sensor heads with different reflective peaks and they can be distinguished in optical spectrum. By compositing several such sensor heads with a multi-channel beam splitter, a star-style topological structure sensor for multipoint sensing is achieved. At the same time, the output intensity at the peak wavelength is sensitive to one external physical parameter applied on the related FBG-cascaded tapered fiber and the central wavelength of the peak is only sensitive to temperature, so that that parameter and temperature can be measured simultaneously. A sensor for dual-point measurement of the displacement and temperature simultaneously is experimentally demonstrated by using a 2 × 2 coupler in this paper. Experiment results show that the sensor works well and the largest sensitivities reach to 0.11 dB/μm for displacement in the range of 0–400 μm, and ∼0.0097 nm/°C for temperature between 20 °C and 70 °C.
Texture and microstructure in co-sputtered Mg-M-O (M = Mg, Al, Cr, Ti, Zr, and Y) films
Authors: Saraiva M. , Depla D.
Published: May 2012

Mg-M-O solid solution films (M = Mg, Al, Cr, Ti, Zr, and Y) with various M contents are grown employing reactive co-sputtering by varying the target-to-substrate distance. It is shown that all films are biaxially aligned. When the two cathodes are equipped with the same target material (Mg), the in-plane alignment is determined by the cathode closest to the substrate, i.e., by the largest material flux. In the case of nearly equal material fluxes from the two cathodes, double in-plane orientation is observed. This is also the case for the Mg-Al-O and Mg-Cr-O films, while the Mg-Ti-O, Mg-Zr-O and Mg-Y-O films exhibit single in-plane orientation. Pole figures indicate that the grains in Mg-M-O (M different than Mg) are titled; in the Mg-Al-O, Mg-Cr-O, and Mg-Ti-O films, the grains tilt towards the Al, Cr, and Ti metal flux, respectively, while the grain tilt of the Mg-Zr-O and Mg-Y-O films is found to be towards the Mg metal flux. Furthermore, SEM cross-sectional images of the Mg-M-O films reveal columnar microstructure with columns tilted to the same direction as the grains. A mechanism which is based on the cation radius change upon the incorporation of an M atom in the MgO lattice is proposed to explain the tilting.
Suppressing electron turbulence and triggering internal transport barriers with reversed magnetic shear in the National Spherical Torus Experiment
Authors: Peterson J. L. , Bell R. , Candy J. , Guttenfelder W. , Hammett G. W. , Kaye S. M. , LeBlanc B. , Mikkelsen D. R. , Smith D. R. , Yuh H. Y.
Published: May 2012

The National Spherical Torus Experiment (NSTX) [M. Ono et al., Nucl. Fusion 40, 557 (2000)] can achieve high electron plasma confinement regimes that are super-critically unstable to the electron temperature gradient driven (ETG) instability. These plasmas, dubbed electron internal transport barriers (e-ITBs), occur when the magnetic shear becomes strongly negative. Using the gyrokinetic code GYRO [J. Candy and R. E. Waltz, J. Comput. Phys. 186, 545 (2003)], the first nonlinear ETG simulations of NSTX e-ITB plasmas reinforce this observation. Local simulations identify a strongly upshifted nonlinear critical gradient for thermal transport that depends on magnetic shear. Global simulations show e-ITB formation can occur when the magnetic shear becomes strongly negative. While the ETG-driven thermal flux at the outer edge of the barrier is large enough to be experimentally relevant, the turbulence cannot propagate past the barrier into the plasma interior.
Ab initio-based double many-body expansion potential energy surface for the first excited triplet state of the ammonia molecule
Authors: Li Y. Q. , Song Y. Z. , Song P. , Li Y. Z. , Ding Y. , Sun M. T. , Ma F. C.
Published: May 2012

A global single-sheeted double many-body expansion potential energy surface is reported for the first excited triplet state of \documentclass[12pt]{minimal}\begin{document}$\rm NH_3$\end{document} NH 3. It employs an approximate cluster expansion of the molecular potential that utilizes previously reported functions of the same family for the triatomic fragments. Four-body energy terms have been calibrated from extensive accurate ab initio data so as to reproduce the main features of the title system. A new switching function formalism has been reported to approximate the true multisheeted nature of \documentclass[12pt]{minimal}\begin{document}${\rm NH_3}({\sideset{^3}{^{\prime \prime }_{2}}{A}})$\end{document} NH 3(A2′′3) potential energy surface, thus allowing the correct behavior at the NH2(2A″) + H(2S) and NH2(4A″) + H(2S) dissociation limits. The resulting fully six-dimensional potential energy function reproduces the correct symmetry under the permutation of identical atoms, and predicts the correct behavior at all dissociation channels while providing a realistic representation at all interatomic separations. The major attributes of the \documentclass[12pt]{minimal}\begin{document}$\rm NH_3$\end{document} NH 3 double many-body expansion potential energy surface have also been characterized, and found to be in good agreement, both with the calculated ones from the raw ab initio energies and the theoretical results available in the literature.
Generalized Gibbs state with modified Redfield solution: Exact agreement up to second order
Authors: Thingna Juzar , Wang Jian-Sheng , Hänggi Peter
Published: May 2012

A novel scheme for the steady state solution of the standard Redfield quantum master equation is developed which yields agreement with the exact result for the corresponding reduced density matrix up to second order in the system-bath coupling strength. We achieve this objective by use of an analytic continuation of the off-diagonal matrix elements of the Redfield solution towards its diagonal limit. Notably, our scheme does not require the provision of yet higher order relaxation tensors. Testing this modified method for a heat bath consisting of a collection of harmonic oscillators we assess that the system relaxes towards its correct coupling-dependent, generalized quantum Gibbs state in second order. We numerically compare our formulation for a damped quantum harmonic system with the nonequilibrium Green's function formalism: we find good agreement at low temperatures for coupling strengths that are even larger than expected from the very regime of validity of the second-order Redfield quantum master equation. Yet another advantage of our method is that it markedly reduces the numerical complexity of the problem; thus, allowing to study efficiently large-sized system Hilbert spaces.