Fabrication and electrical characteristics of high-performance ZnO nanorod field-effect transistors

We report on fabrication and electrical characteristics of high-mobility field-effect transistors (FETs) using ZnO nanorods. For FET fabrications, single-crystal ZnO nanorods were prepared using catalyst-free metalorganic vapor phase epitaxy. Although typical ZnO nanorod FETs exhibited good electrical characteristics, with a transconductance of similar to140 nS and a mobility of 75 cm(2)/V s, the device characteristics were significantly improved by coating a polyimide thin layer on the nanorod surface, exhibiting a large turn-ON/OFF ratio of 10(4)-10(5), a high transconductance of 1.9 muS, and high electron mobility above 1000 cm(2)/V s. The role of the polymer coating in the enhancement of the devices is also discussed. (C) 2004 American Institute of Physics.X11333sciescopu

Thermoelectric properties of Al-doped mesoporous ZnO thin films

Al-doped mesoporous ZnO thin films were synthesized by a sol-gel process and an evaporation-induced self-assembly process. In this work, the effects of Al doping concentration on the electrical conductivity and characterization of mesoporous ZnO thin films were investigated. By changing the Al doping concentration, ZnO grain growth is inhibited, and the mesoporous structure of ZnO is maintained during a relatively high temperature annealing process. The porosity of Al-doped mesoporous ZnO thin films increased slightly with increasing Al doping concentration. Finally, as electrical conductivity was increased as electrons were freed and pore structure was maintained by inhibiting grain growth, the thermoelectric property was enhanced with increasing Al concentration. © 2013 Min-Hee Hong et al

INTERPARTICLE POTENTIAL OF 10 NANOMETER TITANIUM NANOPARTICLES IN LIQUID SODIUM: THEORETICAL APPROACH

A suspension of titanium nanoparticles (Ti NPs) in liquid sodium (Na) has been proposed as a method to mitigate the violent sodium-water reaction (SWR). The interparticle potential between Ti NPs in liquid Na may play a significant role in the agglomeration of NPs on the reaction surface and in the bulk liquid Na, since the potential contributes to a reduction in the long-term dispersion stability. For the effective control of the SWR with NPs, a physical understanding of the molecular dynamics of NPs in liquid Na is key. Therefore in this study, the nonretarded Van der Waals model and the solvation potential model are employed to analyze the interparticle potential. The ab initio calculation reveals that a strong repulsive force driven by the solvation potential exceeds the interparticle attraction and predicts the agglomeration energy required for two 10-nm Ti NPs to be 4 x 10(-17) J. The collision theory suggests that Ti NPs can be effective suppressors of the SWR due to the high energy barrier that prevents significant agglomeration of Ti NPs in quiescent liquid Na. Copyright (C) 2015, Published by Elsevier Korea LLC on behalf of Korean Nuclear Society.110Ysciescopu

Testing for a Debt-Threshold Effect on Output Growth

© 2017 The Authors. Fiscal Studies published by John Wiley & Sons Ltd. on behalf of Institute for Fiscal Studies Using the Reinhart–Rogoff dataset, we find a debt threshold not around 90 per cent but around 30 per cent, above which the median real gross domestic product (GDP) growth falls abruptly. Our work is the first to formally test for threshold effects in the relationship between public debt and median real GDP growth. The null hypothesis of no threshold effect is rejected at the 5 per cent significance level for most cases. While we find no evidence of a threshold around 90 per cent, our findings from the post-war sample suggest that the debt threshold for economic growth may exist around a relatively small debt-to-GDP ratio of 30 per cent. Furthermore, countries with debt-to-GDP ratios above 30 per cent have GDP growth that is 1 percentage point lower at the median

Effects of propolis on streptococcus mutans, actinomyces naeslundii and staphylococcus aureus

It is known that formation of dental caries is caused by the colonization and accumulation of oral microorganisms and extracellular polysaccharides which are synthesized from sucrose by glucosyltransferases of Streptococcus mutans. Actinomyces naeslundii and Staphylococcus aureus are associated with human root caries and some oral mucosa infections, respectively. In this research Streptococcus mutans Ingbritt 1600 exhibiting glucosyltransferase activity was used to test whether different ethanolic extracts of propolis (EEP) inhibit or not the enzyme activity and growth of the bacteria. Antimicrobial activity of EEP against A. naeslundii and S. aureus was also examined. All EEP from various regions in Brazil inhibited both glucosyltransferase activity and growth of S. mutans, A. naeslundii and S. aureus, but one of propolis from Rio Grande do Sul (RS2) demonstrated highest inhibition of the enzyme activity and growth of the bacteria. It was also found that propolis (RS2) contained highest concentrations of pinocembrin and galangin292014314

Effect of surfactant concentration variation on the thermoelectric properties of mesoporous ZnO

The electrical and thermal conductivities and the Seebeck coefficient of mesoporous ZnO thin films were investigated to determine the change of their thermoelectric properties by controlling surfactant concentration in the mesoporous ZnO films, because the thermoelectric properties of mesoporous ZnO films can be influenced by the porosity of the mesoporous structures, which is primarily determined by surfactant concentration in the films. Mesoporous ZnO thin films were successfully synthesized by using sol-gel and evaporation-induced self-assembly processes. Zinc acetate dihydrate and Brij-76 were used as the starting material and pore structure-forming template, respectively. The porosity of mesoporous ZnO thin films increased from 29% to 40% with increasing surfactant molar ratio. Porosity can be easily altered by controlling the molar ratio of surfactant/precursor. The electrical and thermal conductivity and Seebeck coefficients showed a close correlation with the porosity of the films, indicating that the thermoelectric properties of thin films can be changed by altering their porosity. Mesoporous ZnO thin films with the highest porosity had the best thermoelectric properties (the lowest thermal conductivity and the highest Seebeck coefficient) of the films examined. © 2013 Min-Hee Hong et al

The impact of childhood obesity on long-term health burden in the UK

In the UK, 7-10% of the child and adolescent population are currently considered obese according to International Obesity Task Force (IOTF) definitions, and this proportion is expected to rise to 14% over the next 20 years. Childhood obesity is associated with complications including dyslipidemia, insulin resistance, and respiratory problems, and childhood body mass index (BMI) is correlated with BMI in adulthood. However, the ways in which overweight and obesity in early life impact on long-term health are not well understood.This thesis reviews the current evidence for the associations between overweight in childhood and disease outcomes in adulthood, and discusses the limitations of methods that have commonly been used to examine this topic. To investigate the effects of childhood and adolescent overweight on long-term health, pooled data from three British National Birth Cohorts (the 1946 National Survey of Health and Development, 1958 National Child Development Study, and 1970 British Cohort Study) are analysed. The findings of this analysis indicate that being overweight in childhood and adolescence may contribute to increased risk of type 2 diabetes and coronary heart disease, but not hypertension or non-cardiovascular outcomes. Projections from a micro-simulation model show that overweight and obesity in the current UK child population could present a substantial burden in terms of disease prevalence and healthcare costs by the year 2050, and the effects of different obesity interventions on long-term burden are explored.Overweight and obesity in childhood may have important implications for long-term cardiovascular risk, and current trends in childhood obesity prevalence are likely to have a substantial impact on long-term health burden in the UK. Early intervention to reduce overweight in childhood is likely to have an important role in reducing future obesity-related disease burden