局域热源对磁岛热输运的影响

研究托卡马克等离子体磁岛内的热输运行为.应用局域高斯热源对磁岛加热来模拟电子回旋共振加热.对同时存在背景热源与局域高斯热源的情况,观察局域高斯热源对径向电子温度分布及热输运产生的变化,分析局域高斯热源对温度扰动及磁岛约束能量的影响.     

The Fluorescence Enhancement of the Protein Adsorbed on the Surface of Ag Nanoparticle

The fluorescence enhancement of the BSA adsorbed on the surface of Ag nanoparticles is reported, where non-fluorescent collagen is used as the separator between the BSA and Ag nanoparticles. The study indicates that Ag nanoparticles can enhance the fluorescence of the BSA, especially the fluorescence of the tyrosine residues with lower quantum. Three types of Ag nanoparticles are evaluated including Ag island film, Ag colloids and fractal Ag electrode. Of them Ag island film is the best. The investigation suggests that the fluorescence enhancement of the BSA is related to the adsorption of the BSA on the surface of Ag island film through the hydrophobic interaction, while the collagen can promote the adsorption of the BSA on the surface of Ag island film and change its conformation, resulting in the interaction between BSA and Ag island film.     

Spatial variability of 2H and 18O composition of meteoric freshwater lakes in Scotland

Coastal regions, and in particular islands where precipitation from clouds formed out at sea occurs for the first time, are prime candidates for regions where ²H and ¹⁸O composition of precipitation will deviate significantly from the global mean geographic and physiographic trends of vapour-transport patterns. The results reported here are the outcome of a study that aimed to test this hypothesis by ‘isotopographically’ mapping the characteristic δ²H and δ¹⁸O signatures of Scottish freshwaters. The resulting isotope abundance landscapes or ‘isoscapes’ will underpin studies aiming to authenticate origin of Scottish produce but may also offer a baseline against which environmental changes could be assessed. Between April 2011 and May 2012 freshwater samples were collected from 127 different freshwater lochs and reservoirs across Scotland, and analysis results were compared to precipitation data provided by the British Geological Survey. Here we present the results of the ²H and ¹⁸O analyses of these water samples as well as the first detailed Scotland freshwater isoscapes with a grid resolution of about 5 × 5 km (0.05 degrees).     

渔山列岛潮间带生物生态学初步研究

本次调查共鉴定出潮间带生物116种,其中环节动物3种,占总生物种类的2.6%;软体动物45种,占38.8%;甲壳类19种,占16.4%;棘皮动物6种,占5.2%;藻类37种,占31.9%;其他种类6种,占5.2%.潮间带生物资源总平均生物量6760.21g·m-2,平均栖息密度为2750.36 ind·m-2.生物种类数、生物量和栖息密度均为低潮区中潮区高潮区.断面分布不均匀,生物量以大白礁最高,为16006.2g·m-2,小澳次之,为2499.3g·m-2,大沙岙里生物量最低,仅为大白礁生物量的1/10.优势种明显,日本笠藤壶生物量在优势种中占首位,最大生物量达970.91g·m-2;其次为角偏顶蛤,最大生物量为4088.29g·m-2;其他优势种主要有厚壳贻贝、覆瓦小蛇螺和条纹隔贻贝,生物量分别为1406.37,1012.82和949.39g·m-2.     

Tunable surface-plasmon-resonance wavelength of silver island films

This paper experimentally and theoretically investigates the effect of the underlayer medium on tuning of the surface plasmon resonance (SPR) wavelength of silver island films,and the effect of substrate temperature on the morphologies and optical properties of the films.From the absorption spectra of single Ag with various thickness and overcoated (Ag/TiO 2) films deposited on glass substrates at various substrate temperatures by RF magnetron sputtering,we demonstrate that the surface plasmon resonance wavelength can be made tunable by changing the underlayer medium,the thickness of metal layer and the substrate temperature.By varying substrate temperatures,the interparticle coupling effects on plasmon resonances of nanosilver particles enhance as the spacing between the particles reduces.When the substrate temperature is up to 500 C,the absorption peak decreases sharply and shifts to shorter wavelength side due to the severe coalescence between silver islands in the film.     

Study of nanoclusters growth at initial stages of ultrathin film deposition by kinetic modeling

Comparative analysis of Au, Cu, Pt, Ni and Fe nanoclusters growth on amorphous carbon substrate by proposed kinetic model based on rate equations is present. Partial sticking coefficients introduced into the model let to discriminate elementary processes such as adatom adsorption and diffusion on bare substrate and on top of islands, nucleation and mobility of islands and its coalescence, 2-d and 3-d island growth modes. The quantitative fittings of experimental time dependencies of surface coverage, clusters density, cluster size are performed by solving model equations. From the best fittings the values of phenomenological coefficients defining elementary processes are found for different materials. Comparative analysis of those coefficients let to discover mechanisms of nanoclusters formation and growth of different materials. It is shown that clusterization for Cu and Au is more favorable than for Pt and Ni. Diffusivity for Pt and Ni on amorphous carbon (a-C) substrate is significantly less than for Au and Cu. In opposite, diffusivity on the top of islands for Ni and Pt is significantly higher than for Au and Cu. The mobility of islands for Au and Cu is much higher than for Ni and Pt. The fitting of experimental curves of Fe deposition on a-C at different temperatures showed that temperature mainly influences sticking process but not diffusion.     

HL—1装置的硬X射线锯齿振荡

软X射线的锯齿振荡,在ST,Pulsator和TEXT等装置上已观测到;在Pulsator和PLT上已研究了硬X射线锯齿波。PLT和Pulsator观测结果为,产生的硬X射线锯齿振荡为反锯齿和内破裂的软X射线锯齿相对应。Pulsator的硬X射线锯齿和软X射线锯齿一样,这种趋势一直持继到放电结束,而硬X射线峰值发生在软X射线内破裂后大约200μs。PLT的硬X射线锯齿比软X射线锯齿延迟1至5ms。本工作目的是在内破裂后,从软、硬X射线锯齿波对比,观测硬X射线到达峰值这段延迟时间,并以此来量度逃逸电子约束时间。     

A novel method for positioning of InAs islands on GaAs (1 1 0)

A novel method for positioning of InAs islands on GaAs (1 1 0) by cleaved edge overgrowth is reported. The first growth sample contains strained In_xGa_1−xAs/GaAs superlattice (SL) of varying indium fraction, which acts as a strain nanopattern for the cleaved-edge overgrowth. Atoms incident on the cleaved edge will preferentially migrate to InGaAs regions where favorable bonding sites are available. By this method InAs island chains with lateral periodicity defined by the thickness of InGaAs and GaAs of SL have been realized by molecular beam epitaxy (MBE). They are observed by means of atomic force microscopy (AFM). The strain nanopattern's effect is studied by the different indium fraction of SL and MBE growth conditions.     

Computer simulation for the pervaporation process of wate/ethanol mixture through interpenetrating polymer network (IPN) membranes

In this study, the pervaporation behavior of EtOH-water mixture through interpenetrating polymer network (IPN) membranes was predicted. The pervaporation characteristics of single component membranes were modelled according to the “six coefficients model” proposed by Brun [J. Membrane Sci., 23 (1985) 257]. In the case of the IPN membrane, two models were proposed according to the phase structure of the IPN. For a uniphase membrane with no phase separation, the compositional averages of the single component membrane coefficients were used. In the case of the phase separated IPN, two cases exist. The first is the island and sea model: one phase is continuous and the other is discrete. The second is the cocontinuous model, in which two continuous phases exist. For these cases the permeation rate and separation factor of the IPN membrane were calculated using the experimental sorption data and pure component values for each IPN composition. Comparison with the experimental data indicates that these models could be to predict the performances of IPN membranes depending on the morphology of the IPN.