Role of interface dipole in metal gate/high-k effective work function modulation by aluminum incorporation

The interface dipole and its role in the effective work function (EWF) modulation by Al incorporation are investigated. Our study shows that the interface dipole located at the high-k/SiO2 interface causes an electrostatic potential difference across the metal/high-k interface, which significantly shifts the band alignment between the metal and high-k, consequently modulating the EWF. The electrochemical potential equalization and electrostatic potential methods are used to evaluate the interface dipole and its contribution. The calculated EWF modulation agrees with experimental data and can provide insight to the control of EWF in future pMOS technology.

Role of interface absorption in laser-induced local heating of optical coatings

Considering the interface absorption in optical coatings, we propose a model to simulate interface absorption. Calculations are made and the temperature field of several kinds of thin film multilayers, including those of partial reflectivity, high-reflectivity, and antireflectivity coatings are analyzed. The interface absorption is found to greatly influence the temperature distribution within multilayer coatings and to weaken the laser damage resistance of the samples. The real-time results of the photothermal deflection technique for laser induced damage to samples supports the model. (C) 1997 Society of Photo-Optical Instrumentation Engineers.

The role of MC1R gene in buffalo coat color

Melanocortin-1 receptor (MC1R) plays a major role in pigmentation in many species. To investigate if the MC1R gene is associated with coat color in water buffalo, the coding region of MC1R gene of 216 buffalo samples was sequenced, which included 49 black river buffalo (Murrah and Nili-Ravi), 136 swamp buffalo (Dehong, Diandongnan, Dechang, Guizhou, and Xilin) with white and gray body, and 31 hybrid offspring of river buffalo Nili-Ravi (or Murrah) and swamp buffalo. Among the three variation sites found, SNP684 was synonymous, while SNP310 and SNP384 were nonsynonymous, leading to p.S104G and p.I128M changes, respectively. Only Individuals carrying homozygote E-BR/E-BR were black. The genotype and phenotype analysis of the hybrid offspring of black river buffalo and gray swamp buffalo further revealed that the river buffalo type allele E-BR or the allele carrying the amino acid p.104S was important for the full function of MC1R. The in silico functional analysis showed that the amino acid substitutions p.G104S and p.M128I had significant impact on the function of MC1R. Above results indicate that the allele E-BR or the allele carrying the amino acid p.104S was associated with the black coat color in buffalo.

The Critically Endangered black crested gibbon Nomascus concolor on Wuliang Mountain, Yunnan, China: the role of forest types in the species' conservation

The Critically Endangered black crested gibbon Nomascus concolor of China, Laos and Vietnam is threatened by deforestation and habitat destruction but there have been no studies of how it uses its forest habitat, probably because of the typically rugged t

The Essential Role of Endogenous Ghrelin in Growth Hormone Expression during Zebrafish Adenohypophysis Development

Ghrelin, a multifunctional hormone, including potent GH stimulation activity, has been suggested to be important during embryonic development. Expression of ghrelin has been confirmed in the zebrafish pancreas during embryonic stages. Interfering with ghrelin function using two specific antisense morpholino oligonucleotides causes defects during zebrafish embryonic development. In ghrelin morphants the expression of GH was abolished in zebrafish somatotropes, whereas the expression patterns of the other key molecules involved in hypothalamic-pituitary development and distinct pituitary hormones genes remain largely intact at the appropriate time during zebrafish adenohypophysis development. Effective rescue of the ghrelin morphants with exogenous ghrelin mRNA showed that the correct gene had been targeted. Moreover, by analyzing the efficiencies of the ghrelin morphants rescue experiments with various forms of exogenous mutant ghrelin mRNAs, we also demonstrated the essentiality of the form acyl-ghrelin on GH stimulation during zebrafish adenohypophysis development. Our in vivo experiments, for the first time, also provided evidence of the existence of functional obestatin in the C-terminal part of zebrafish proghrelin peptides. Our research here has demonstrated that zebrafish is a unique model for functional studies of endogenous ghrelin, especially during embryonic development. (Endocrinology 150: 2767-2774, 2009)

The role of glutathione metabolism in tolerance of tobacco BY-2 suspension cells to microcystin-RR

This study was undertaken to investigate the role of the glutathione-involved detoxifying mechanism in defending the tobacco BY-2 suspension cells against microcystin-RR (MC-RR). Analysis showed that exposure of the cells to different concentrations of MC-RR (0.1, 1 and 10 mu g/mL) for 0-6 days resulted in a time and concentration-dependent decrease in cell viability and increase in reactive oxygen species (ROS) content. Reduced glutathione (GSH) and total glutathione (tGSH) content as well as glutathione reductase (GR), glutathione peroxidase (GPX) and glutathione-S-transferase (GST) activities significantly increased after 3-4 days exposure in the highest two concentration treated groups, while decreased until reaching the control values except for GPX at day 6. Oxidized glutathione (GSSG) content markedly increased compared with control in high concentration MC-RR treated group after 6 days exposure. The GSH/GSSG ratio was much higher than control in 10 mu g/mL MC-RR treated group at day 4, but after 6 days exposure, the ratios in all treated groups were lower than that of the control group.

The role of NH4+ toxicity in the decline of the submersed macrophyte Vallisneria natans in lakes of the Yangtze River basin, China

Experimental and field studies were conducted to evaluate the effects of NH4+ enrichment on growth and distribution of the submersed macrophyte, Vallisneria natans L, in lakes of the Yangtze River in China, based on the balance between free amino acids (FAA) and soluble carbohydrates (SC) in the plant tissue. Increase of NH4+ rather than NO3- concentrations in the water column caused FAA accumulation and SC depletion of the plant. The plant showed a unimodal pattern of biomass distribution along both FAA/SC ratios and external NH4+ concentrations, indicating that a moderate NH4-N concentration (< 0.3 mg L-1) benefited the plant, whereas the high NH4-N concentration (> 0.56 mg L-1) eliminated the plant completely. Therefore, 0.56 mg NH4-N mg L-1 in the water column was taken as the upper limit for V. natans in lakes of the Yangtze River basin. The mesocosm experiment showed that at a high external NH4-N (0.81 mg L-1), V. natans failed to propagate with a loss of half SC content (5 mg g(-1) DW) in the rhizomes, indicating that the consumption of carbohydrates for detoxification of excess NH4+ into non-toxic FAA significantly diminished carbohydrate supply to the rhizomes. This might consequently inhibit the vegetative reproduction of the plant, and also might be an important cause for the decline and disappearance of the plant with eutrophication. The present study for the first time reports substantial ecophysiological evidences for NH4+ stress to submersed macrophytes, and indicates that NH4+ toxicity arising from eutrophication probably plays a key role in the deterioration of submersed macrophytes like V. natans.

The role of sense organs in the feeding behaviour of Chinese perch

Experiments were conducted to identify the rules of the individual sense organs in the feeding behaviour of Chinese perch Siniperca chuatsi by determining the consumption of natural food after selective removal or blocking of eyes, lateral lines and olfactory organs, and also by observing the behavioural response to visual, mechanical and chemical stimulation by artificial prey. Chinese perch were able to feed properly on live prey fish when either eyes or lateral lines were intact or functional, but could scarcely feed without these two senses. Chinese perch recognized its prey by vision through the perception of motion and shape, and showed a greater dependence on vision in predation when both visual and mechanical cues were available. Chemical stimulation by natural food could not elicit any feeding response in Chinese perch, and gustation was only important to the fish for the last stage of food discrimination in the oropharyngeal cavity. The sensory basis of Chinese perch in feeding is well adapted to its nocturnal stalking hunting strategy. and also explains its peculiar food habit of accepting live prey fish only and refusing dead prey fish or artificial diets. (C) 1998 The Fisheries Society of the British Isles.

ROLE OF PHOSPHORUS CYCLING IN ALGAL METABOLISM AND ALGAL SUCCESSION IN LAKE DONGHU, CHINA

The role of phosphorus cycling in algal metabolism was studied in a shallow lake, Donghu, in Wuhan using the methods of measuring cell quota C, N and P, and calculating nutrients uptake rate by algal photosynthesis. The mean daily phosphorus uptake rate of phytoplankton varied between 0.04-0.11 and 0.027-0.053 g/m2/d in station I and station II respectively. The turnover time of phosphorus in phytoplankton metabolism ranged from 0.75-5.0 days during 1979-1986. The available P was 0.176 (+/- 0.156) g/m3 (mean +/- SD) in 1982 and 0.591 (+/- 0.24) g/m3 in 1986. The relationship between P/B ratio (Y) and TP (X: mg/l) was described by the following regression equation Y = 1.163 + 0.512logX (r = 0.731, P < 0.001). The dynamics of algal biomass and algal species succession were monitored as the indicators of environmental enrichment. The small-sized algae have replaced the blue-green algae as the dominant species during 1979-1986. The small-sized algae include Merismopedia glauca, Cryptomonas ovata, Cryptomonas erosa, several species Cyclotella. There has been drastic decrease in algal biomass and an obvious increase in P/B ratio. A nutrient competition hypothesis is proposed to explain the reason of the disappearance of blue-green algae bloom. The drastic change in algal size and the results in high P/B ratio (reaching a maximum mean daily ratio of 1.09 in 1986) may suggest a transition of algal species from K-selection to r-selection in Lake Donghu.

Role of Ga vacancies in enhancing the leakage current of GaN Schottky barrier ultraviolet photodetectors

The leakage current of GaN Schottky barrier ultraviolet photodetectors is investigated. It is found that the photodetectors adopting undoped GaN instead of lightly Si-doped GaN as an active layer show a much lower leakage current even when they have a higher dislocation density. It is also found that the density of Ga vacancies in undoped GaN is much lower than in Si-doped GaN. The Ga vacancies may enhance tunneling and reduce effective Schottky barrier height, leading to an increase of leakage current. It suggests that when undoped GaN is used as the active layer, it is necessary to reduce the leakage current of GaN Schottky barrier ultraviolet photodetector.