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

Photoluminescent characteristics of Ni-catalyzed GaN nanowires

The authors report on time-integrated and time-resolved photoluminescence (PL) of GaN nanowires grown by the Ni-catalyst-assisted vapor-liquid-solid method. From PL spectra of Ni-catalyzed GaN nanowires at 10 K, several PL peaks were observed at 3.472, 3.437, and 3.266 eV, respectively. PL peaks at 3.472 and 3.266 eV are attributed to neutral-donor-bound excitons and donor-acceptor pair, respectively. Furthermore, according to the results from temperature-dependent and time-resolved PL measurements, the origin of the PL peak at 3.437 eV is also discussed. (c) 2006 American Institute of Physics.X1147sciescopu

Effects of environmental enrichment on survivorship, growth, sex ratio and behaviour in laboratory maintained zebrafish Danio rerio

This is the author accepted manuscriptEnvironmental enrichment involves increasing the complexity of a fish's environment in order to improve welfare. Researchers are legally obliged to consider the welfare of laboratory animals and poor welfare may result in less robust data in experimental science. Laboratory zebrafish Danio rerio are usually kept in bare aquaria for ease of husbandry and, despite being a well-studied species, little is known about how laboratory housing affects their welfare. This study shows that environmental enrichment, in the form of the addition of gravel substratum and plants into the tank, affects survivorship, growth and behaviour in laboratory-maintained D. rerio. Larvae reared in enriched tanks had significantly higher survivorship compared with larvae reared in bare tanks. Effects of the tank conditions on growth were more variable. Females from enriched tanks had a higher body condition than females maintained in bare tanks, but intriguingly this was not the case for males, where the only difference was a more variable body condition in males maintained in bare tanks. Sex ratio in the rearing tanks did not differ between treatments. Resource monopolisation was higher for fish in enriched tanks than for those in bare tanks. Fish from enriched tanks displayed lower levels of behaviours associated with anxiety compared with fish from bare tanks when placed into a novel environment. Thus, this study demonstrates differences in welfare for D. rerio maintained under different environmental conditions with enhancements in welfare more commonly associated with tank enrichment.University of Exeter Aquatic Resources Centr

Vertically aligned ZnO nanostructures grown on graphene layers

We report the vertical growth of ZnO nanostructures on graphene layers and their photoluminescence (PL) characteristics. ZnO nanostructures were grown vertically on the graphene layers using catalyst-free metal-organic vapor-phase epitaxy. The surface morphology of the ZnO nanostructures on the graphene layers depended strongly on the growth temperature. Further, interesting growth behavior leading to the formation of aligned ZnO nanoneedles in a row and vertically aligned nanowalls was also observed and explained in terms of enhanced nucleation on graphene step edges and kinks. Additionally, the optical characteristics and carbon incorporation into ZnO were investigated using variable-temperature PL spectroscopy.open11121134sciescopu

Effect of solar fraction on the economic performance of a solar air conditioning by an adsorption chiller / F. Basrawi et al.

Solar cooling is a promising way for a sustainable air-conditioning system. However, since solar has intermittent output, it is usually backed-up by a conventional heater. Thus, it still needs electricity or fossil fuel to operate stabily. This study presents the effect of ratio of heat delivered by solar to the total heat delivered to an adsorption chiller (solar fraction) on the economic performance of a solar cooling system. This cooling system need covers cooling demand for an office building in a tropical region (Kuala Lumpur). Cooling demand was simulated using well-known energy analysis software for building, Equest. Flat-plate collectors and an adsorption chiller were the main component of the cooling system. Flat-plate collecters were simulated using another software, Watsun, and the adsorption chiller was based on our simulation model that is comparable with other studies. Economic performance was analyzed by life cycle cost analysis. Solar fraction of 0.33, 0.74 and 0.98 were studied. It was found that none of the solar fraction studied can generate Net Profit under subsidized electricity. It was also found that a natural gas boiler is a better solution than an electric heater as an auxiliary heater in term of economic. For a natural gas boiler, Net Profit increased when solar fraction decreased; the highest one was solar fraction of 0.33 with US$15,600. However, since more energy is used for the auxiliary heater in lower solar fraction, more emissions is expected to be released. Thus, emissions for all solar fraction need to be considered and studied further

Vaccines for prophylaxis of viral infections in patients with hematological malignancies.

Viral infections cause significant morbidity and mortality in patients with hematological malignancies. It remains uncertain whether viral vaccinations in these patients are supported by good evidence. We aimed to determine the effectiveness and safety of viral vaccines in patients with hematological malignancies. We searched Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, CINAHL (June 2010), reference lists of relevant papers, abstracts from scientific meetings and contacted vaccine manufacturers. Randomized controlled trials (RCTs) evaluating viral vaccines in patients with hematological malignancies were included. Relative risk (RR) was used for binary data and mean difference (MD) for continuous data. Primary outcome was incidence of infection. Secondary outcomes were mortality, incidence of complications and severe viral infection, hospitalization, immune response and adverse effects. Fixed-effect model was used in meta-analyses. Eight RCTs were included, with 305 patients in the intervention groups and 288 in the control groups. They evaluated heat-inactivated varicella zoster virus (VZV) vaccine (two trials), influenza vaccines (five trials) and inactivated poliovirus vaccine (IPV) (one trial). Seven trials had high and one trial had moderate risk of bias.VZV vaccine might reduce herpes zoster compared to no vaccine (RR 0.54, 95% CI 0.3 to 1.0, P=0.05), but not statistically significant. Vaccination also demonstrated efficacy in immune response but frequently caused local adverse effects. One trial reported severity score of zoster, which favored vaccination (MD 2.6, 95% CI 0.94 to 4.26, P=0.002).Two RCTs compared inactivated influenza vaccine with no vaccine and reported lower risk of lower respiratory infections (RR 0.39, 95% CI 0.19 to 0.78, P=0.008) and hospitalization (RR 0.17, 95% CI 0.09 to 0.31, P<0.00001) in vaccine recipients. However, vaccine recipients more frequently experienced irritability and local adverse effects. There was no significant difference in seroconversion between one and two doses of influenza vaccine (one trial), or between recombinant and standard influenza vaccine (one trial), or influenza vaccine given with or without re-induction chemotherapy (one trial).The IPV trial comparing vaccination starting at 6 versus 18 months after stem cell transplant (SCT) found no significant difference in seroconversion. Inactivated VZV vaccine might reduce zoster severity in adult SCT recipients. Inactivated influenza vaccine might reduce respiratory infections and hospitalization in adults with multiple myeloma or children with leukemia or lymphoma. However, the quality of evidence is low. Local adverse effects occur frequently. Further high-quality RCTs are needed.link_to_subscribed_fulltex

Thermoelectric power measurements of wide band gap semiconducting nanowires

We investigated the temperature-dependent thermoelectric power (TEP) of individual wide band gap ZnO and GaN semiconducting nanowires by fabricating the devices with good Ohmic contacts. In the temperature range of 10-300 K, the measured TEP of both nanowires was linearly dependent on temperature, indicating the degenerate doping nature of these nanowires. The room temperature TEP value of ZnO nanowires was as high as -400 mu V/K while an order of magnitude smaller TEP value was observed in GaN. The negative sign of TEP values shows that electrons are the majority carriers in these wide band gap nanowires. More importantly, in comparison with gate-dependent transport measurements of the nanowire field effect transistors, analysis of temperature-dependent TEP measurements provides a reliable way of estimating the majority carrier concentration of nanowires, where conventional Hall effect measurements cannot be used.open116075sciescopu

Enhanced field emission properties from well-aligned zinc oxide nanoneedles grown on the Au/Ti/n-Si substrate

The authors investigated the field emission from vertically well-aligned zinc oxide (ZnO) nanoneedles grown on the Au/Ti/n-Si (100) substrate using metal organic chemical vapor deposition. The turn-on field of ZnO nanoneedles was about 0.85 V/mu m at the current density of 0.1 mu A/cm(2), and the emission current density of 1 mA/cm(2) was achieved at the applied electric field of 5.0 V/mu m. The low turn-on field of the ZnO nanoneedles was attributed to very sharp tip morphology, and the high emission current density was mainly caused by the formation of the stable Ohmic contact between the ZnO nanoneedles and Au film. (c) 2007 American Institute of Physics.open117999sciescopu

Triple Higgs coupling in the most general 2HDM at SM-like scenario

We consider the triple Higgs coupling for h(125) Higgs boson within the most general 2HDM. At moderate values of parameters of model, allowing by modern data, noticeable deviation of this coupling from its SM value is improbable. This deviation can be sizable only if some measurable parameters of the model are exotic