bluuebunny/crossref_metadata_2025 huggingface dataset:
Vasopressor use in free tissue transfer surgery
Authors: Monroe Marcus M. , McClelland Julie , Swide Chris , Wax Mark K.
Published: January 2010

Objective

To document the frequency of vasopressor use in free tissue transfer surgery and to compare the incidence of flap complications and flap survival in patients receiving or not receiving intraoperative vasopressors.

Study Design and Setting

Case series with chart review of free tissue transfers performed between 2004 and 2006 at a large‐volume tertiary academic hospital.

Results

Of 241 free flaps, 169 had data available for analysis. Flap survival was 96.5 percent. The rate of other flap complications was 29 percent. A total of 139 (82%) patients received vasopressors intraoperatively. Of these, four (2.9%) flap failures and 40 (29%) complications occurred. In the 30 (18%) patients who did not receive vasopressors, two (6.7%) flap failures and nine (30%) complications occurred. The most common reasons for flap failure were arterial thrombus (n = 3) and thrombosis of the venous pedicle (n = 3).

Conclusion

Intraoperative vasopressors are used more frequently than previously realized but do not appear to increase overall flap failure and the incidence of complications. Intraoperative vasopressor use in free flap surgery may not be as harmful as previously feared.
Homocysteine-lowering vitamins do not lower plasmaS-adenosylhomocysteine in older people with elevated homocysteine concentrations
Authors: Green Timothy J. , Skeaff C. Murray , McMahon Jennifer A. , Venn Bernard J. , Williams Sheila M. , Devlin Angela M. , Innis Sheila M.
Published: January 2010

Elevated plasma total homocysteine (tHcy) is a risk factor for vascular disease but lowering tHcy with B-vitamins, including folate, has generally not reduced vascular events in secondary prevention trials. Elevated plasmaS-adenosylhomocysteine (AdoHcy) concentration may be a more sensitive indicator of vascular disease than plasma tHcy. However, unlike tHcy, plasma AdoHcy did not correlate with folate concentration in one study indicating that folate supplementation may not lower AdoHcy. Our aim was to determine whether providing B-vitamin supplements to healthy older people with elevated tHcy (>13 μmol/l) affects plasma AdoHcy andS-adenosylmethionine (AdoMet) concentrations. Healthy older participants (n276; ≥ 65 years) were randomised to receive a daily supplement containing folate (1 mg), vitamin B12(500 μg) and vitamin B6(10 mg), or placebo, for 2 years. Of these participants, we selected the first fifty participants in each treatment group and measured plasma AdoHcy and AdoMet. Plasma tHcy was 4·4 (95 % CI 3·2, 5·6;P < 0·001) μmol/l lower at 2 years in the vitamins group compared with the placebo group. At 2 years, there were no significant differences in plasma AdoMet (+4 % (95 % CI − 2, 11);P = 0·19), AdoHcy ( − 1 % (95 % CI − 10, 8);P = 0·61) or the AdoMet:AdoHcy ratio (0·22 (95 % CI − 0·04, 0·49);P = 0·10) between the two groups. In conclusion, B-vitamin supplementation of older people lowered plasma tHcy but had no effect on plasma AdoMet or AdoHcy concentration. If elevated plasma AdoHcy is detrimental, this may explain why B-vitamins have generally failed to reduce vascular events in clinical trials.
Adherence to the Mediterranean dietary pattern among Balearic Islands adolescents
Authors: Martínez Elisa , Llull Rosa , del Mar Bibiloni Maria , Pons Antoni , Tur Josep A.
Published: January 2010

The aim of the present work was to assess the prevalence of the Mediterranean dietary pattern (MDP) in Balearic Islands adolescents, and socio-demographic and lifestyle factors that might determine adherence to the MDP. A cross-sectional nutritional survey was carried out in the Balearic Islands between 2007 and 2008. A random sample (n1231) of the adolescent population (12–17 years old) was interviewed. Dietary questionnaires and a general questionnaire incorporating questions related to socio-economic status, parental education level and lifestyle factors were used. Dietary habits were assessed by means of two 24 h recalls and a quantitative FFQ. Adherence to the MDP was defined according to a score constructed considering the consumption of nine MDP characteristic components: high MUFA:SFA ratio, moderate ethanol consumption, high legumes, cereals and roots, fruits, vegetables and fish consumption, and low consumption of meat and milk. Then, socio-demographic, lifestyle and health status variables that could determine a higher or ower adherence were assessed. The mean adherence was 57·9 (sd8·9) % and the median adherence was 57·3 %. Half of the Balearic Islands adolescents (50·5 %) showed an adherence to the MDP comprised between 52·7 and 62·8 %. By multivariate analyses, a high maternal level of education, increased physical activity, reduced alcohol intake and abstinence from smoking were independent associations of better adherence to the MDP. The promotion of not only the MDP but also the Mediterranean lifestyle, including greater physical activity, should be reinforced among the Balearic younger generations.
Arbitrary amplitude solitary waves in plasmas with dust grains of opposite polarity and non-thermal ions
Authors: MAHARAJ S. K. , BHARUTHRAM R. , SINGH S. V. , PILLAY S. R. , LAKHINA G. S.
Published: January 2010

The existence of large amplitude solitary waves in a plasma comprised of a cold negative dust fluid, adiabatic positive dust fluid, Boltzmann electrons and non-thermal ions is theoretically investigated. Different regions in parameter space that correspond to different values of the ratio of the charge-to-mass ratios of the positive and negative dust grains have been identified where either negative or positive potential solitary wave structures occur and a region where coexistence of negative and positive potential solitary waves is supported.
How to achieve resilience as an older widower: turning points or gradual change?
Authors: BENNETT KATE M.
Published: January 2010

The paper draws together two conceptualisations of resilience in bereavement and widowhood that were developed by Bonanno (2004) and Moore and Stratton (2003), both using North American data. This paper has re-examined data from two United Kingdom studies of widowerhood. Among an aggregate sample of 60 widowers, 38 per cent showed resilience in the face of the exacting challenges that late-life widowhood brings. Resilient men were seen as having a positively viewed biography, were participating in relationships and activities, and had returned to a life that had meaning and brought satisfaction. Four broad categories among the resilient widowers were identified. The first had been resilient consistently throughout their widowhood. The second group achieved resilience gradually, and the third following a turning point. Finally, a small group of men demonstrated both gradual and turning point pathways towards resilience. Personal characteristics had been particularly influential for those in the first group, while for the last group, social support had made an important contribution to achieving resilience and had two forms: informal and formal. The paper concludes with a discussion of the implications of the differentiation of resilience for adaptation to bereavement amongst older men.
Time and money volunteering among older adults: the relationship between past and current volunteering and correlates of change and stability
Authors: CHOI NAMKEE G. , CHOU RITA JING-ANN
Published: January 2010

Using data from the first and second waves of the Survey of Midlife Development in the United States – MIDUS1 1995–1996 and MIDUS2 2004–2006, this paper examines the relationship between the extent of time and money volunteering among people aged 55 or more years at baseline and those of the same age nine years later. Following an analysis of the changes and stability in volunteering status, the paper examines the relationships between change or stability in volunteering and various socio-demographic attributes of the respondents and measures of their human capital, cultural capital and social capital. A majority of older volunteers of time and/or money were repeat volunteers, and the extent of volunteering at the start of the studied period was one of the most significant predictors of the extent of volunteering nine years later. The level of education was a consistent predictor of the extent of both time and money volunteering and of new engagement and stability in volunteering. Social network size, or social connectedness, represented by the number of various meetings attended, was a significant predictor not only of the hours of time volunteering, but also of new engagement and stability in both time and money volunteering. A high degree of religious identification also appeared to be a motivation for money volunteering and to affect the value of donations. The paper concludes by discussing the implications of the findings for the recruitment and retention of volunteers.
Perceptions and expectations of pension savings adequacy: a comparative study of Dutch and American workers
Authors: VAN DALEN HENDRIK P. , HENKENS KÈNE , HERSHEY DOUGLAS A.
Published: January 2010

What drives the perceptions of pension savings adequacy and what do workers expect to receive when they retire? These questions are assessed among married workers using an identical survey distributed to Dutch and American workers in 2007. Despite marked differences in expected pension replacement rates – where the Dutch replacement rates are systematically higher than the American rates – the perceived savings adequacy is more or less the same across Dutch and American workers. In both countries, about half of the respondents were confident they had amassed sufficient retirement savings. Individuals' perceived savings adequacy was found to be influenced by three groups of factors: trust in pension institutions (pension funds, banks, insurance companies and governments), social forces and psychological dispositions. This study shows that differences in the dispositions of workers (with respect to future orientation and financial planning) played a far larger role in explaining differences in perceptions of savings adequacy in the United States than in The Netherlands. Dutch workers rely and trust their pension fund and seem to leave thinking about and planning for retirement to its managers.
Relativistic and ponderomotive effects on evolution of laser beam in a non-uniform plasma channel
Authors: Gill T.S. , Mahajan R. , Kaur R.
Published: January 2010

The nonlinear parabolic partial differential equation governing the evolution of the complex envelope in the slowly varying envelope approximation is solved using the variational approach. The basic nonlinear phenomena of relativistic and ponderomotive self-focusing in a plasma channel are taken into account. Self-focusing, self-phase modulation as well as self-trapping of laser beam is studied in a variety of situations. Further, in the absence of dissipation mechanisms, the stability of the beam is also studied.
Generation of attosecond X-ray pulses via Thomson scattering of counter-propagating laser pulses
Authors: Liu L. , Xia C.-Q. , Liu J.-S. , Wang W.-T. , Cai Y. , Wang C. , Li R.-X. , Xu Z.-Z.
Published: January 2010

It is proposed that single attosecond pulses be generated via electron's Thomson scattering of two counter-propagating laser pulses. In the case of linear polarization, the generation of a single attosecond pulse is highly sensitive to the carrier envelope phase (CEP). However, in the case of circular polarization, it is completely independent on the CEP, which will make circular polarization favorable to generate a stable attosecond X-ray pulse. For either linear or circular polarization, the radiation obtained by using two counter-propagating pulses can be much more intense than that obtained by only using one of these two pulses.
Radiative reaction effect on electron dynamics in an ultra intense laser field
Authors: Mao Q.Q. , Kong Q. , Ho Y.K. , Che H.O. , Ban H.Y. , Gu Y.J. , Kawata S.
Published: January 2010

The radiative reaction effect of an electron is usually very small and can be neglected in most cases. But for an ultra intensity laser-electron interaction region, the radiation can become large. The influence of the radiative reaction effect of an electron interacting with an ultra intense laser pulses in vacuum on electron dynamics is investigated within the classical relativistic Lorentz-Dirac approach. A predictor-corrector method is proposed to numerically solve the equation of motion with the electron radiative reaction included. We study the counter-propagating case (for Thomson scattering scheme) and the same direction propagating cases (for laser acceleration). Our simulation results show that radiation can have great effect in the counter-propagating case. But in the vacuum laser electron acceleration regime, both the ponderomotive acceleration scenario case and the capture and acceleration scenario, radiative reaction effect can totally be ignored for laser intensity available presently or in the near-future.
Power Can Increase Stereotyping
Authors: Guinote Ana , Phillips Adele
Published: January 2010

Previous research indicates that power increases attention to stereotype-consistent information. The ecological validity of this hypothesis was tested in managers and subordinates in the hotel industry. Participants were presented with stereotype-consistent and stereotype-inconsistent information about an ingroup or outgroup target, and their task was to judge the suitability of the target for a job that was either consistent or inconsistent with the stereotype. Subordinates attended more to individuating information and paid overall more attention to social information than managers. In addition, the managers’ judgments of the suitability of the outgroup target were dependent on the stereotype consistency of the job, whereas the subordinates’ judgments were not. These findings are consistent with experimental research and shed light on the conditions that promote stereotyping and discrimination.
Bayesian nonparametric inference for earthquake recurrence time distributions in different tectonic regimes
Authors: Rotondi R.
Published: January 2010

The objective of this paper is to estimate the probability distribution of the time between consecutive earthquakes by employing two equally powerful tools: for the geology, a database of individual seismogenic sources, and for the statistics, assuming that the unknown distribution is a random measure, an estimation method based on the stochastic simulation of Markov chains. The resort to sophisticated instruments is motivated by the particular situation of Italy, where a complex tectonic model is combined with infrequent, medium‐size earthquakes. The quality and the length of the parametric catalogue of Italian earthquakes provide for a generous data set but bring with them problems of incompleteness and uncertainty regarding the parametrization of the events. The pointwise estimate of the interevent time density functions makes it possible to calculate the occurrence probability depending on the date of the last event at different forecasting horizons.
European ozone in a future climate: Importance of changes in dry deposition and isoprene emissions
Authors: Andersson Camilla , Engardt Magnuz
Published: January 2010

Projections of future surface ozone over Europe conducted utilizing chemistry transport models (CTMs) coupled to climate models differ greatly, even in sign. CTM sensitivity studies were conducted in order to investigate the importance of changes in natural isoprene emissions and dry deposition to vegetation, both coupled to meteorology. This knowledge can be used to improve surface ozone projections. Our simulations suggest climate change over Europe would cause changes in surface ozone between −4.0 to +13 ppb(v) on average (April–September) and −3.5 to +25 ppb(v) on average (April–September) daily maximum from 1961–1990 to 2071–2100. The change is positive in the southwest and negative in the north. The isoprene emissions increased by a factor of about 1.8 from 1961–1990 to 2071–2100. A rescaling of isoprene emissions shows that the large increase in isoprene emission is of importance (0–30% of the change in surface ozone) in central, southern, and western Europe. The use of a formulation for ozone dry deposition to vegetation, dependent on meteorology, and changes in snow cover, affecting the dry deposition, are more important processes. The changes in dry deposition to vegetation (not including changes in aerodynamic resistance) explain up to 80% of the surface ozone change in Spain. Therefore it is vital to include meteorological dependence for dry deposition of ozone to vegetation in surface ozone projections. Isoprene emissions are of less importance, but they are nonnegligible and should definitely be emitted online in climate ozone projection studies.
Horizontal and vertical zoning of heterogeneities in the Hawaiian mantle plume from the geochemistry of consecutive postshield volcano pairs: Kohala‐Mahukona and Mauna Kea–Hualalai
Authors: Hanano Diane , Weis Dominique , Scoates James S. , Aciego Sarah , DePaolo Donald J.
Published: January 2010

Sr‐Nd‐Pb‐Hf isotopic compositions of postshield lavas from two pairs of Hawaiian volcanoes, Mauna Kea and Kohala (Kea trend) and Hualalai and Mahukona (Loa trend), allow for identification of small‐scale (tens of kilometers) heterogeneities in the Hawaiian mantle plume and provide constraints on their distribution. The postshield lavas range from transitional/alkalic basalt to trachyte and are enriched in incompatible trace elements (e.g., LaN/YbN = 6.0–16.2). These lavas are characterized by a limited range of Sr‐Nd‐Hf isotopic compositions (87Sr/86Sr = 0.70343–0.70365, 143Nd/144Nd = 0.51292–0.51301, and 176Hf/177Hf = 0.28311–0.28314) and have distinct Pb isotopic compositions (206Pb/204Pb = 17.89–18.44, 207Pb/204Pb = 15.44–15.49, and 208Pb/204Pb = 37.68–38.01) that correspond to their respective Kea or Loa side of the Pb‐Pb isotopic boundary. Mauna Kea lavas show a systematic shift to less radiogenic Pb isotopic compositions from the shield to postshield stage and they trend to low 87Sr/86Sr toward, but not as extreme as, compositions characteristic of rejuvenated stage lavas. Hualalai postshield lavas lie distinctly above the Hf‐Nd Hawaiian array and have much lower Pb isotopic ratios than shield lavas, including some of the least radiogenic values (e.g., 206Pb/204Pb = 17.89–18.01) of recent Hawaiian volcanoes. In contrast, comparison of Kohala with the adjacent Mahukona volcano shows that these older postshield lavas become more radiogenic in Pb during the late stages of volcanism. The isotope systematics of the postshield lavas cannot be explained by mixing between Hawaiian plume end‐members (e.g., Kea, Koolau, and Loihi) or by assimilation of Pacific lithosphere and are consistent with the presence of ancient recycled lower oceanic crust (±sediments) in their source. More than one depleted component is sampled by the postshield lavas and these components are long‐lived features of the Hawaiian plume that are present in both the Kea and Loa source regions. The depleted components in the postshield lavas, particularly as sampled at Hualalai, are different from the much more homogeneous component present in rejuvenated lavas. The geochemistry of the postshield lavas provides evidence for a bilateral symmetry to the plume where the compositional boundary between the Kea and Loa sources is complex and vertical components of heterogeneity are significant.
Future change in Southern Hemisphere summertime and wintertime atmospheric blockings simulated using a 20‐km‐mesh AGCM
Authors: Matsueda Mio , Endo Hirokazu , Mizuta Ryo
Published: January 2010

Future changes in the frequency of Australia–New Zealand (AU; winter and summer) and Andes (AN; winter) blockings are investigated via present‐day (1979–2003) and future (2075–2099) simulations using 20‐, 60‐, and 180‐km‐mesh atmospheric general circulation models (AGCMs) under the IPCC SRES A1B emission scenario. The present‐day climate simulations reveal that the AGCM with the highest horizontal resolution is required to accurately simulate AU and AN blockings in both winter and summer. The future climate simulation predicts a significant decrease in AU blocking frequency in both summer and winter, mainly on the west side of the peak in present‐day blocking frequency, where the westerly jet is predicted to increase in strength. The decrease in the AU blocking frequency during winter is more remarkable than that during summer. The number of long‐lived AU blocking events is predicted to decrease with the possibility that events ≥13 days will disappear altogether. In contrast, no significant changes are predicted in AN blocking frequency and duration.
Resolving intercontinental pollution plumes in global models of atmospheric transport
Authors: Rastigejev Yevgenii , Park Rokjin , Brenner Michael P. , Jacob Daniel J.
Published: January 2010

Synoptic‐scale pollution plumes in the free troposphere can preserve their identity as well‐defined structures for a week or more while traveling around the globe. Eulerian chemical transport models (CTMs) have difficulty reproducing these layered structures due to numerical plume dissipation. We show that this dissipation is much faster than would be expected from the order of the advection scheme because of interaction between numerical diffusion and the nonuniformity of the atmospheric flow. The nonuniform flow stretches out the plume, enhancing the effect of numerical diffusion. For sufficiently strong stretching, the numerical decay of the plume is independent of the model grid resolution and is set instead by the flow Lyapunov exponent λ. In this regime, conventional numerical methods are not convergent: upon increasing grid resolution, the plume still decays with the same decay rate. The critical plume size below which the numerical scheme does not converge is set by the geometric mean of the grid spacing and the characteristic length scale l = v/λ over which the flow varies, where v is the wind speed. Above this critical plume size the numerically induced decay rate of the plume scales like the square root of the grid spacing. Application to an intercontinental pollution plume in a global CTM with realistic atmospheric flow shows that proper simulation of such a plume would require an impractical increase in grid resolution. Novel methods such as adaptive grids or embedded Lagrangian plumes are needed.
Optical characterization of dissolved organic matter in tropical rivers of the Guayana Shield, Venezuela
Authors: Yamashita Youhei , Maie Nagamitsu , Briceño Henry , Jaffé Rudolf
Published: January 2010

Tropical rivers are an important source of dissolved organic matter (DOM) to coastal oceans. However, temporal and spatial variability of DOM composition and thus its quality in such rivers, on landscape and basin scales, have not been well documented. In this study, we present data on the spatial distribution of DOM quantity and quality based on source, molecular weight, and composition using optical properties including excitation emission matrix fluorescence with parallel factor analysis. We compared such DOM quantity and quality determinations in main river channels and their tributaries for three river systems of the Guayana Shield, Venezuela. Spatial variabilities of DOM parameters were strongly related to differences in the geological settings of the drainage basins and presumably their associated vegetation cover. Linear relationships between quantitative and qualitative DOM parameters were also evident, suggesting that high DOC concentration correlated with chromophoric dissolved organic matter (CDOM) characteristics of higher molecular weight associated with terrestrial sources, while low DOC concentrations correlated with CDOM characteristics of lower molecular weight associated primarily with microbial sources. Such relationships seem to imply that DOM concentrations and their sources/characteristics may be coupled in the studied fluvial systems. In addition, shifts in DOM compositions between terrestrial and microbial signals were observed with changes in water discharge and in watersheds disturbed by gold mining activities. The observed linkages between, and the changes among DOM quantity and quality, suggest that the biogeochemistry of DOM in tropical rivers may be quite sensitive to climatic and land use change.
Comparison of the anaerobic microbiota of deep-water Geodia spp. and sandy sediments in the Straits of Florida
Authors: Brück Wolfram M , Brück Thomas B , Self William T , Reed John K , Nitecki Sonja S , McCarthy Peter J
Published: January 2010

Marine sediments and sponges may show steep variations in redox potential, providing niches for both aerobic and anaerobic microorganisms. Geodia spp. and sediment specimens from the Straits of Florida were fixed using paraformaldehyde and 95% ethanol (v/v) for fluorescence in situ hybridization (FISH). In addition, homogenates of sponge and sediment samples were incubated anaerobically on various cysteine supplemented agars. FISH analysis showed a prominent similarity of microbiota in sediments and Geodia spp. samples. Furthermore, the presence of sulfate-reducing and annamox bacteria as well as other obligate anaerobic microorganisms in both Geodia spp. and sediment samples were also confirmed. Anaerobic cultures obtained from the homogenates allowed the isolation of a variety of facultative anaerobes, primarily Bacillus spp. and Vibrio spp. Obligate anaerobes such as Desulfovibrio spp. and Clostridium spp. were also found. We also provide the first evidence for a culturable marine member of the Chloroflexi, which may enter into symbiotic relationships with deep-water sponges such as Geodia spp. Resuspended sediment particles, may provide a source of microorganisms able to associate or form a symbiotic relationship with sponges.
Experimental factors affecting PCR-based estimates of microbial species richness and evenness
Authors: Engelbrektson Anna , Kunin Victor , Wrighton Kelly C , Zvenigorodsky Natasha , Chen Feng , Ochman Howard , Hugenholtz Philip
Published: January 2010

Pyrosequencing of 16S rRNA gene amplicons for microbial community profiling can, for equivalent costs, yield more than two orders of magnitude more sensitivity than traditional PCR cloning and Sanger sequencing. With this increased sensitivity and the ability to analyze multiple samples in parallel, it has become possible to evaluate several technical aspects of PCR-based community structure profiling methods. We tested the effect of amplicon length and primer pair on estimates of species richness (number of species) and evenness (relative abundance of species) by assessing the potentially tractable microbial community residing in the termite hindgut. Two regions of the 16S rRNA gene were sequenced from one of two common priming sites, spanning the V1–V2 or V8 regions, using amplicons ranging in length from 352 to 1443 bp. Our results show that both amplicon length and primer pair markedly influence estimates of richness and evenness. However, estimates of species evenness are consistent among different primer pairs targeting the same region. These results highlight the importance of experimental methodology when comparing diversity estimates across communities.
Implementation Methods for Estimating Haplotypes with Grid Computing Technology
Authors: Muhammad Zafri , KC Sanjaya , Kia Kien Phua
Published: January 2010

Introduction: PHASE is a software for haplotype reconstruction and recombination rate estimation from population data and implements the methods for estimating haplotypes from population genotype data. This software require enormous computing power due to the complexity algorithms used. Recent advancement in grid computing and multi-core processing technology has resulted in the creating of virtual supercomputers (that are capable of massive parallel computations).

Method:

PHASE version 2.0 was downloaded from PHASE’s homepage (http://stephenslab.uchicago.edu/software.html), and installed on 10 Apple iMac computers (20 CPUs) running Mac OS 10.5 using Apple™ Xserve as a controller. A PHP web-based application was developed to enable easy job submission and result retrieval. Haplotype estimation jobs for PHASE were submitted using a web browser running either from Windows®, Linux® or Macintosh™ OS 10.5 operating systems. Jobs consisting of 20 input files of genomic loci (SNPs) were submitted to the Xgrid via the controller and the job completion time for each run were recorded and compared.

Results:

The job completion time for estimating 20 input files and returning the results to the controller using XGrid (20 CPUs) took 4,980 seconds compared with 58,800 seconds using a single computer (2 CPUs), representing 91.5% reduction in computing time.
Synthesis of 4,5-diheteroarylphenanthrenes and their dinuclear ruthenium(ii) bis(2,2′:6′,2″-terpyridine) complexes possessing severe helical twists
Authors: Wen Bo , Petersen Jeffrey L. , Wang Kung K.
Published: January 2010

Two helical dinuclear Ru(ii) bis(terpyridine) complexes were synthesized from a derivative of 4,5-bis(2,2′:6″,2″-terpyridyl)phenanthrene.
Size dependent oxygen buffering capacity of ceria nanocrystals
Authors: Xu Jiahui , Harmer Jeffrey , Li Guoqiang , Chapman Thomas , Collier Paul , Longworth Sarennah , Tsang Shik Chi
Published: January 2010

The structural, chemical and electronic changes of ceria as a function of decreasing particle size have been studied: at sizes below 5 nm the total amount of reducible oxygen dramatically increases due to superoxide formation on the ceria surface, a result indicative of a size dependent oxygen buffering capacity.
Highly fluorescent water-soluble polyglycerol-dendronized perylene bisimide dyes
Authors: Heek Timm , Fasting Carlo , Rest Christina , Zhang Xin , Würthner Frank , Haag Rainer
Published: January 2010

Water-soluble perylene tetracarboxylic acid bisimides with terminally linked polyglycerol dendrons [G1–G4] reveal a strong dendritic effect, enabling outstanding fluorescence quantum yields in water for [G3] and [G4] dendrons.
Geometry effects on thermoelectric properties of silicon nanowires based on electronic band structures
Authors: Liang Gengchiau , Huang Wen , Koong Chee Shin , Wang Jian-Sheng , Lan Jinghua
Published: January 2010

The thermoelectric properties of silicon nanowires with different shapes, sizes, and orientations are theoretically investigated using sp3d5s∗ tight-binding model coupled with ballistic transport approach. We found that the thermoelectric properties significantly depend on nanowire geometry. Compared to [111] and [100] nanowires, n-doped and p-doped [110] nanowires show the worst performance in terms of power factor per cross-section area and figure of merit (ZT). As nanowire size decreases, thermoelectric properties of nanowires can be enhanced. As a result, triangular nanowires with side length of 1 nm have the best results of ZT and it can be enhanced to 1.5 and 0.85 for an n-type nanowire along [111] orientation and a p-type nanowire along [100] orientation, respectively. For extremely narrow nanowires, thermoelectric properties are only dependent on the number of the transmission modes instead of material properties such as carrier effective mass. Moreover, cross-section shape and thermal conductance contributed by electrons play important roles in ZT while their influence can be ignored for large size nanowires. Even though smaller size nanowires have better performance with the consideration of the single nanowire thermoelectric properties, they might be less efficient than larger diameter nanowires, as packing space is not very dense.
Multireference quantum chemistry through a joint density matrix renormalization group and canonical transformation theory
Authors: Yanai Takeshi , Kurashige Yuki , Neuscamman Eric , Chan Garnet Kin-Lic
Published: January 2010

We describe the joint application of the density matrix renormalization group and canonical transformation theory to multireference quantum chemistry. The density matrix renormalization group provides the ability to describe static correlation in large active spaces, while the canonical transformation theory provides a high-order description of the dynamic correlation effects. We demonstrate the joint theory in two benchmark systems designed to test the dynamic and static correlation capabilities of the methods, namely, (i) total correlation energies in long polyenes and (ii) the isomerization curve of the [Cu2O2]2+ core. The largest complete active spaces and atomic orbital basis sets treated by the joint DMRG-CT theory in these systems correspond to a (24e,24o) active space and 268 atomic orbitals in the polyenes and a (28e,32o) active space and 278 atomic orbitals in [Cu2O2]2+.
Two-dimensional time-resolved x-ray diffraction study of dual phase rapid solidification in steels
Authors: Yonemura Mitsuharu , Osuki Takahiro , Terasaki Hidenori , Komizo Yuichi , Sato Masugu , Toyokawa Hidenori , Nozaki Akiko
Published: January 2010

The high intensity heat source used for fusion welding creates steep thermal gradients of 100 °C/s from 1800 °C. Further, the influence of preferred orientation is important for the observation of a directional solidification that follows the dendrite growth along the ⟨100⟩ direction toward the moving heat source. In the present study, we observed the rapid solidification of weld metal at a time resolution of 0.01–0.1 s by a two-dimensional time-resolved x-ray diffraction (2DTRXRD) system for real welding. The diffraction rings were dynamically observed by 2DTRXRD with synchrotron energy of 18 keV while the arc passes over the irradiation area of the x-rays. The arc power output was 10 V-150 A, and the scan speed of the arc was 1.0 mm/s. The temperature rise in instruments was suppressed by a water-cooled copper plate under the specimen. Further, the temperature distribution of the weld metal was measured by a thermocouple and correlated with the diffraction patterns. Consequently, solidification and solid phase transformation of low carbon steels and stainless steels were observed during rapid cooling by 2DTRXRD. In the low carbon steel, the microstructure is formed in a two step process, (i) formation of crystallites and (ii) increase of crystallinity. In stainless steel, the irregular interface layer of δ/γ in the quenched metal after solidification is expected to show the easy movement of dendrites at a lower temperature. In carbide precipitation stainless steel, it is easy for NbC to grow on δ phase with a little undercooling. Further, a mistlike pattern, which differs from the halo pattern, in the fusion zone gave some indication of the possibilities to observe the nucleation and the early solidification by 2DTRXRD.
Improved performance and reliability for metal-oxide-semiconductor field-effect-transistor with fluorinated silicate glass passivation layer
Authors: Hsieh Chih-Ren , Chen Yung-Yu , Lou Jen-Chung
Published: January 2010

The superior characteristics of the fluorinated HfO2/SiON gate dielectric are investigated comprehensively. Fluorine is incorporated into the gate dielectric through fluorinated silicate glass (FSG) passivation layer to form fluorinated HfO2/SiON dielectric. Fluorine incorporation has been proved to eliminate both bulk and interface trap densities due to Hf–F and Si–F bonds formation, which can strongly reduce trap generation as well as trap-assisted tunneling during subsequently constant voltage stress, and results in improved electrical characteristics and dielectric reliabilities. The results clearly indicate that the fluorinated HfO2/SiON gate dielectric using FSG passivation layer becomes a feasible technology for future ultrathin gate dielectric applications.
Magnetostrictive and structural properties of FeCoGa films
Authors: Jen S. U. , Tsai T. L. , Kuo P. C. , Chi W. L. , Cheng W. C.
Published: January 2010

Fe 81 − x Co x Ga 19 (with x ranging from 0 to 19 at. % Co) films were made by the dc magnetron sputtering method. We have studied the structural (phases, texturing, and grain size D), magnetic (saturation magnetostriction λS and coercivity HC), mechanical (Young’s modulus Ef and hardness Hf), and electrical (electrical resistivity ρ) properties of these films. The main results are as follows: (i) all the films are (110) textured; (ii) the bct phase (with twinned grains) coexists with the bcc phase only in the case of x≤3 at. % Co; (iii) λS increases steadily from 42 to 86 ppm, as x increases from 0 to 19 at. % Co; and (iv) ρ reaches the saturation limit, about 200 μΩ cm, when 19≥x≥15 at. % Co. In conclusion, we report that the Fe62Co19Ga19 film has the optimal magnetic, mechanical, and electrical properties among all the FeCoGa films measured.
Numerical approach for retention characteristics of double floating-gate memories
Authors: Tanamoto Tetsufumi , Muraoka Kouichi
Published: January 2010

We report on a numerical investigation in which memory characteristics of double floating-gate (DFG) structure were compared to those of the conventional single floating-gate structure, including an interference effect between two cells. We found that the advantage of the DFG structure is its longer retention time and the disadvantage is its smaller threshold voltage shift. We also provide an analytical form of charging energy including the interference effect.
The Sc2 dimer revisited
Authors: Kalemos Apostolos , Kaplan Ilya G. , Mavridis Aristides
Published: January 2010

Thirty two states of the homonuclear neutral diatomic Sc2 molecule have been studied by multireference methods using basis sets of quadruple quality. For all 30 states resulting from the ground state Sc atoms, Sc(D2g)+Sc(D2g), and two out of 80, X Σ5u− and 1 Σ3u−, issued from the first excited channel Sc(D2g)+Sc(a F4g), we have constructed full potential energy curves and extracted the standard spectroscopic parameters. With the exception of X Σ5u− and 1 Σ3u− which are covalently bound, the 30 states related to the ground state Sc atoms are of van der Waals nature with interaction energies of 3–5 kcal/mol at distances of 7–7.5 bohr. For the X Σ5u− state the proposed De value is 48 kcal/mol, with respect to the adiabatic fragments and with the 1 Σ3u− state just 380 cm−1 above it.
Melting of Zn nanoparticles embedded in SiO2 at high temperatures: Effects on surface plasmon resonances
Authors: Amekura H. , Tanaka M. , Katsuya Y. , Yoshikawa H. , Shinotsuka H. , Tanuma S. , Ohnuma M. , Matsushita Y. , Kobayashi K. , Buchal Ch. , Mantl S. , Kishimoto N.
Published: January 2010

Zn nanoparticles at room temperature show two absorption peaks in the near-infrared (NIR) and the ultraviolet (UV) regions, both of which satisfy the criterion of surface plasmon resonance (SPR). From x-ray diffraction at high temperatures, it was found that the Zn nanoparticles in SiO2 melt at 360–420 °C and solidify at 250–310 °C with a large temperature hysteresis. While the NIR peak disappears with melting, the UV peak shows sudden energy shift with melting but survives even after the melting. The first-principle band calculation ascribes the UV and NIR peaks to SPR-enhanced inter- and intraband transitions, respectively.
Controlled directional growth of silver microwires on a solid electrolyte surface
Authors: Hsu Keng , Ferreira Placid , Fang Nicholas
Published: January 2010

A silver microwire was formed on a silver sulfide surface in a directional and reversible manner. This wire formed upon applying an electric field between a tip-less atomic force microscopy probe placed on the Ag2S surface and a grounded silver electrode embedded in the surface. The process was studied in real-time with optical microscope and a discussion was provided on how the morphological instability was violated. A numerical model based on the mixed ionic-electronic transport was developed to study the observation and a good match of growth rates was found. The fast metal wire growth phenomenon observed here has potential in applications for electronics as well as plasmonic sensors and waveguides
Ab initio study on pressure-induced change of effective Coulomb interaction in superconducting yttrium
Authors: Kim Duck Young , Ahuja Rajeev
Published: January 2010

Ab initio lattice dynamics based on linear response method are performed for high pressure phase of yttrium to describe electron-phonon coupling and subsequent superconducting behavior. The critical temperature Tc in fcc-Y increases monotonically with pressure up to 9.25 K at 31 GPa, which is quantitatively in excellent agreement with two quasihydrostatic experiments and is qualitatively compatible with recent experiments. The excellent agreement with experiments gives us a better understanding of the effective pseudopotential μ∗ as well as spectral function α2(ω)F(ω) in yttrium. These results demonstrate that there exists strong electron-phonon coupling in Y within the studied pressure regime, and for lower pressure electron correlation becomes stronger. Generally, it is found that superconductivity in yttrium under pressure can be described quantitatively within standard theory of phonon-mediated superconductivity.
Surface plasmon enhanced photoconductance and single electron effects in mesoporous titania nanofibers loaded with gold nanoparticles
Authors: Son Min-Soo , Im Ji-Eun , Wang Kang-Kyun , Oh Seung-Lim , Kim Yong-Rok , Yoo Kyung-Hwa
Published: January 2010

We have synthesized mesoporous TiO2 nanofibers loaded with Au nanoparticles (MTNF-Au) and fabricated single nanofiber-based devices. MTNF-Au devices exhibited surface plasmon enhanced photoconductance under visible light, whereas MTNF devices without Au nanoparticles did not. Moreover, Coulomb oscillations were observed at 4.2 K in MTNF-Au devices, indicating that Au nanoparticles embedded in MTNF-Au played a role of Coulomb islands. These results suggested that the enhanced photoconductance was ascribed to electron tunneling of hot electrons generated by the surface plasmon resonance.
Band bowing and band alignment in InGaN alloys
Authors: Moses Poul Georg , Van de Walle Chris G.
Published: January 2010

We use density functional theory calculations with the HSE06 hybrid exchange-correlation functional to investigate InGaN alloys and accurately determine band gaps and band alignments. We find a strong band-gap bowing at low In content. Band positions on an absolute energy scale are determined from surface calculations. The resulting GaN/InN valence-band offset is 0.62 eV. The dependence of InGaN valence-band alignment on In content is found to be almost linear. Based on the values of band gaps and band alignments, we conclude that InGaN fulfills the requirements for a photoelectrochemical electrode for In contents up to 50%.
Mechanism of effective three-photon induced lasing
Authors: Fan H. H. , He Y. J. , Dong J. W. , Chen B. C. , Wang H. Z. , Tian Y. P. , Reid M. F.
Published: January 2010

The experimental and theoretical results in this letter reveal that three-photon absorption effect can help light wave to form solitonlike filament; and a stable solitonlike filament is observed in solution with high quintic nonlinearity. This stable solitonlike filament makes pumping infrared laser be localized within the filament and reach high pumping density for a long distance. This high density pumping laser in the filament generates high efficiency lasing induced by three-photon absorption. This work is an approach to make practical application of high order nonlinear optical processes possible.
Self-injection of electrons in a laser-wakefield accelerator by using longitudinal density ripple
Authors: Dahiya Deepak , Sajal Vivek , Sharma A. K.
Published: January 2010

By introducing a longitudinal density ripple (periodic modulation in background plasma density), we demonstrate self-injection of electrons in a laser-wakefield accelerator. The wakefield driven plasma wave, in presence of density ripple excites two side band waves of same frequency but different wave numbers. One of these side bands, having smaller phase velocity compared to wakefield driven plasma wave, preaccelerates the background plasma electrons. Significant number of these preaccelerated electrons get trapped in the laser-wakefield and further accelerated to higher energies.
Volume magnetic domain mirroring in magnetic shape memory crystals
Authors: Lai Yiu-Wai , Schäfer Rudolf , Schultz Ludwig , McCord Jeffrey
Published: January 2010

From the magnetic domain patterns at adjacent crystal surfaces of NiMnGa shape memory crystals the internal domain configurations across a hidden twin-boundary are derived. The results proof the existence of domains extending from the sample surfaces into the nonvisible sample volume. Moreover, the structural twin boundary inside the material acts as a mirror for the basic domains. The analysis validates the relevance of surface magnetic response analysis for the understanding of the magnetoelastic behavior of magnetic shape memory alloys and is essential for the interpretation of magnetic domain images obtained from other surface-restricted observation techniques.
DNA damage and mitochondria dysfunction in cell apoptosis induced by nonthermal air plasma
Authors: Kim G. J. , Kim W. , Kim K. T. , Lee J. K.
Published: January 2010

Nonthermal plasma is known to induce animal cell death but the mechanism is not yet clear. Here, cellular and biochemical regulation of cell apoptosis is demonstrated for plasma treated cells. Surface type nonthermal air plasma triggered apoptosis of B16F10 mouse melanoma cancer cells causing DNA damage and mitochondria dysfunction. Plasma treatment activated caspase-3, apoptosis executioner. The plasma treated cells also accumulated gamma-H2A.X, marker for DNA double strand breaks, and p53 tumor suppressor gene as a response to DNA damage. Interestingly, cytochrome C was released from mitochondria and its membrane potential was changed significantly.
Enhanced multiferroicity in Mg-doped Ca3Co2−xMnxO6
Authors: Li L. , Luo W. Z. , Guo Y. J. , Li S. Z. , Luo S. J. , Wang K. F. , Liu J.-M.
Published: January 2010

Polycrystalline Ca3−xMgxCo2−yMnyO6 (y∼1.0) samples are prepared in order to investigate the A-site doping effect of Ca3Co2−yMnyO6 (y∼1.0). Compared with Ca3Co2−yMnyO6 (y∼1.0), the ferroelectric polarization and Curie point of Ca3−xMgxCo2−yMnyO6 (y∼1.0) at the maximal doping x∼0.3 are significantly enhanced. The magnetic order of Ca3−xMgxCo2−yMnyO6 (x∼0.3, y∼1.0) and thus ferroelectric order are more robust than the undoped compound. The slight lattice shrinking as a result of Mg substitution may contribute to the enhancement of exchange striction, leading to the changes in magnetic and ferroelectric properties.
Surface effects on nanoscale Poiseuille flows under large driving force
Authors: Liu Chong , Li Zhigang
Published: January 2010

In this work, we examine the effects of fluid-wall interaction on the fluid flux of nanoscale Poiseuille flows under large external driving force. The mass fluxes of liquid Ar and He confined by two parallel planar walls are measured by molecular dynamics simulations. For liquid Ar, a bimodal behavior in the flux is observed as the effective surface effect is varied. However, the bimodal behavior for Ar is not observed for He. At weak fluid-wall interactions, the flux of He is independent of fluid-wall binding energy, while it decreases monotonously with increasing fluid-wall binding energy when the fluid-wall interaction is strong.