Generation of solid-density ultraintense ion beams by a picosecond laser pulse of circular polarization

This contribution reports particle-in-cell numerical studies of deuteron beam acceleration by a picosecond laser pulse of circular polarization. The effect of laser wavelength λ and the I(L)λ(2) product (I(L) is laser intensity) on the ion beam parameters is investigated. It is shown that at the I(L)λ(2) product fixed, the beam parameters (, I(i), F(i)) as well as the laser-ions energy conversion efficiency quickly increase with a decrease in the laser wavelength and the best results are achieved for a KrF laser (λ = 0.248 μm). In particular, a 2-ps KrF laser pulse of I(L)λ(2) ～ 2 × 10(20) Wcm(-2) μm(2) interacting with a 10-μm deuteron target produces a quasi-monoenergetic, solid-density deuteron beam of parameters approaching those required for inertial confinement fusion fast ignition.     

TEM study of the structural dependence of the epitaxial passive oxide films on crystal facets in polyhedral nanoparticles of chromium

Nanocubes and partially truncated rhombic dodecahedral nanoparticles of Cr have been studied by electron diffraction, high-resolution transmission electron microscopy and X-ray photoelectron spectroscopy. It is found that the nanoparticles of Cr are enclosed by the epitaxial passive oxide films. The oxide films on 100% truncated nanocubes of Cr with only one kind of facets, (100) facets, are face-centered cubic (fcc) structured Cr(2)O(3) with a lattice constant of 0.407nm. There are two kinds of oxide films in partially truncated nanoparticles of Cr with two kinds of crystallographic facets, (100) and (110). The same fcc Cr(2)O(3) is found on the (100) facets while the rhombohedral [Formula: see text] -Cr(2)O(3) is found on the (110) facets. This is similar to the two kinds of oxides, fcc and rhombohedral Fe(2)O(3), which have also been observed in polyhedral nanoparticles of Fe. These passive Cr(2)O(3), found in nanoparticles of Cr which have remained unchanged in water for four years, may have important implications for protective oxide films involving Cr.     

Characterization of micellar film morphologies of semifluorinated block copolymers by AFM

The micellar morphologies of well-defined amphiphilic block copolymers composed of 1H,1H-dihydroperfluorooctyl methacrylate (FOMA) and ethylene oxide (EO) blocks with different chain lengths were effectively investigated by using tapping mode-atomic force microscopy (TM-AFM). By spin-casting chloroform solutions, well-ordered spherical micellar films could be obtained for poly(FOMA(10k)-b-EO(10k)) and poly(FOMA(20k)-b-EO(20k)) copolymers. The atomic force microscopy (AFM) height and phase image analysis indicated that dark regions of the micelles corresponded to PEO blocks and the light regions were for PFOMA blocks. The spherical micelles with PEO corona and PFOMA core were also identified by transmission electron microscopy (TEM) and X-ray photoelectron spectrometer (XPS) analysis. The core diameters of the block-copolymer aggregates were 20nm for poly(FOMA(10k)-b-EO(10k)) and 30nm for poly(FOMA(20k)-b-EO(20k)) by TM-AFM, whereas slightly lower values of 17 and 26nm were obtained from TEM. A detailed study on the inverted morphological change observed in the micelles films after annealing above glass transition temperature (T(g)) was also presented.     

Influence of genotype and explant source on indirect organogenesis by in vitro culture of leaves of Melia azedarach L.

In vitro regeneration of shoots from leaf explants of the Paradise tree (Melia azedarach L.) was studied. Three different portions (proximal portion, distal portion and rachis of the leaflets) of three developmental stages (folded, young still expanding and completely expanded) of leaves of 10-15 year old plants of seven genotypes were cultured on Murashige and Skoog (1962) medium (MS) supplemented with 1 mg x l(-1) benzylaminopurine (BAP) + 0.1 mg x l(-1) kinetin (KIN) + 3 mg x l(-1) adenine sulphate (ADS). The rachis of the leaflets of the completely expanded leaves was found to be the most responsive tissue, in most of the genotypes employed. Shoot regeneration occurred in leaf explants of all the genotypes tested. The best genotype for shoot regeneration was clone 4. Rooting was induced on MS medium supplemented with 2.5 mg x l(-1) 3-indolebutyric acid, IBA, (4 days) followed by subculture on MS lacking growth regulators (26 days). Complete plants were transferred to soil.     

锗原子量的新测定(英文)

用两种高富集锗同位素配制的标准混合溶液系列 ,以标定一台 MAT-2 62热电离质谱仪 ,求得 4个同位素丰度比的校准因数 ,从而测得 5种天然锗样品的 4个同位素丰度比的真值。由此计算天然锗 5种同位素的丰度值如下 :2 0 .37± 0 .0 5　　原子 %70 Ge2 7.38± 0 .0 4　　原子 %72 Ge7.76± 0 .0 5　　原子 %73 Ge36.66± 0 .0 5　　原子 %74 Ge7.83± 0 .0 5　　原子 %76Ge再各乘以已知的原子质量 ,得出锗原子量的新值为 :Ar( Ge) =72 .639± 0 .0 0 4这些精确数值的置信度为 95%。优于文献上所有已知的相应值。     

Modes of axial collapse of unconstrained capped frusta

Efforts are made to classify the modes of deformation of unconstrained capped end frusta when crushed axially between two parallel plates. Tens of aluminum spun capped end frusta of different semi-apex angles (15–60°) and thicknesses (1–3 mm) are crushed at quasi-static loading conditions using a universal instron machine. The resulting modes of deformation can be classified into: (1) outward inversion, (2) limited inward inversion followed by outward inversion, (3) full inward inversion followed by outward inversion, (4) limited extensible crumpling followed by outward inversion, and (5) full extensible crumpling. Samples of frusta made of low carbon steel sheets and nylon plastic were tested statically and gave similar results. An explicit version of ABAQUS 5.8 finite element (FE) program is used to model the crushing modes. Good agreement is obtained between the FE predictions and the experimental work.     

Effects of morphological control on the characteristics of vertical-type OTFTs using Alq3

We have fabricated vertical-type organic thin-film transistors (OTFTs) using tris-(8-hydroxyquinoline) aluminum (Alq(3)) as an n-type active material. Vertical-type OTFT using Alq(3) has a layered structure of Al(source electrode)/Alq(3)(active layer)/Al(gate electrode)/Alq(3)(active layer)/ITO glass(drain electrode). Alq(3) thin films containing various surface morphologies could be obtained by the control of evaporation rate and substrate temperature. The effects of the morphological control of Alq(3) thin layer on the grain size and the flatness of film surface were investigated. The characteristics of vertical-type OTFT significantly influenced the growth condition of Alq(3) layer.     

弱激光对神经元瞬时外向钾通道电流特性的影响

应用全细胞膜片钳技术,研究了急性分离的大鼠海马CA3区锥体神经细胞在波长670 nm、功率5 mW的半导体激光器照射时,其瞬时外向钾通道电流特性。实验发现:弱激光对瞬时外向钾电流I_A有抑制作用,5 min激光抑制作用达到稳定,去极化至+50 mV时抑制百分比为(40.13±5.19)%(n=10);弱激光对I_A的抑制作用呈现电压依赖性和可逆性,对照组、照射组和恢复组的最大激活电流密度分别为(398.55±36.49)pA/pF、(238.62±30.78)pA/pF(n=10,P<0.01)和(354.08±35.16)pA/pF(n=10,P>0.05);激光作用可显著地影响瞬时外向钾通道电流的稳态激活和失活过程,对照组和激光照射组通道的半数激活电压分别为(-27.05±4.53) mV和(-2.10±3.14) mV(n=10, P<0.01),斜率因子分别为(-26.71±6.15) mV和(-20.70±4.38) mV(n=10,P<0.05),半数失活电压分别为(-70.49±7.21) mV和(-81.27±6.26) mV(n=10, P<0.01),斜率因子分别为(9.47±3.54) mV和(9.58±3.02) mV(n=10,P>0.05)。结果表明:弱激光作用海马神经元可以改变其瞬时外向钾通道特性,从而影响动作电位的形成和发放,调节神经元的生理功能,有利于受损神经元的恢复和再生。     

光谱学在有机导体研究中的应用

有机电荷转移复合物的光谱表征对于了解样品的电子结构、电性能和单晶结构相的归属是一种行之有效的手段。本文报道了我们在这方面所做的一些工作:(BEDT-TTF)_3Cl_2(H_2O)_2、(BEDT-TTF)_2、Cl(H_2O)_3的KBr压片的从中红外到可见、紫外区域的光谱和(BEDT-TTF)_5Cl_3(H_2O)_5的红外偏振光谱图。这些工作对于这些有机导体的进一步研究很有帮助。     

Development of a high-efficiency high-resolution particle-induced x-ray emission system for chemical state analysis of environmental samples

We have developed a high-efficiency high-resolution particle-induced x-ray emission (PIXE) system employing a von Hamos-type crystal spectrometer for a chemical state identification of trace elements in environmental samples. The energy resolution of the system was determined to be about 0.05% through the observation of Si Kalpha(1,2) x rays (1.74 keV) from elemental silicon. The throughput efficiency of the system was also evaluated quasitheoretically to be 1.6x10(-7) counts/incident proton for Si Kalpha(1,2) emission. To demonstrate a chemical state analysis using the high-resolution PIXE system, Si Kalpha(1,2) and Kbeta x-ray spectra for SiC, Si(3)N(4), and SiO(2) were measured and compared. The observed chemical shifts of the Si Kalpha(1,2) peaks for SiC, Si(3)N(4), and SiO(2) relative to elemental silicon were 0.20, 0.40, and 0.55 eV, respectively. The tendency of these shifts were well explained by the effective charges of the silicon atoms calculated by a molecular orbital method.     

One-step preparation of hybrid materials of polyacrylamide networks and gold nanoparticles

Hybrid materials of polyacrylamide networks and gold nanoparticles were prepared by directly heating an aqueous solution containing HAuCl(4), acrylamide, N,N'-methylenebis-acrylamide, and sodium sulfite (Na(2)SO(3)). Acrylamide, N,N'-methylenebis-acrylamide, and Na(2)SO(3) were used as monomers, crosslinking agent, and initiator, respectively. In the process of polyacrylamide network synthesis, HAuCl(4) was reduced by acrylamide and Na(2)SO(3) into gold nanoparticles and adsorbed on the produced polyacrylamide networks. Transmission electron microscopy proved that the size of gold nanoparticles was in the range of 3-10 nm. Atomic force microscopy showed that the gold nanoparticles homogeneously dispersed into the polyacrylamide networks matrix. The hybrid materials as absorbents may be useful in healthcare, communication technology, building industry, chromatography, water purification, and agriculture.     

Precise measurements of the total concentration of atmospheric CO2 and 13CO2/12CO2 isotopic ratio using a lead-salt laser diode spectrometer

We have developed a tunable diode laser spectrometer, called SIMCO (spectrometer for isotopic measurements of CO(2)), for determining the concentrations of (12)CO(2) and (13)CO(2) in atmospheric air, from which the total concentration of CO(2) and the isotopic composition (expressed in delta units) delta(13)CO(2) are calculated. The two concentrations are measured using a pair of lines around 2290.1 cm(-1), by fitting a line profile model, taking into account the confinement narrowing effect to achieve a better accuracy. Using the Allan variance, we have demonstrated (for an integration time of 25 s) a precision of 0.1 ppmv for the total CO(2) concentration and of 0.3[per thousand] for delta(13)CO(2). The performances on atmospheric air have been tested during a 3 days campaign by comparing the SIMCO instrument with a gas chromatograph (GC) for the measurement of the total CO(2) concentration and with an isotopic ratio mass spectrometer (MS) for the isotopic composition. The CO(2) concentration measurements of SIMCO are in very good agreement with the GC data with a mean difference of Delta(CO(2))=0.16+/-1.20 ppmv for a comparison period of 45 h and the linearity of the concentration between the two instruments is also very good (slope of correlation: 0.9996+/-0.0003) over the range between 380 and 415 ppmv. For delta(13)CO(2), the comparison with the MS data shows a larger mean difference of Delta(delta(13)CO(2))=(-1.9+/-1.2)[per thousand], which could be partly related to small residual fluctuations of the overall SIMCO instrument response.     

Optimal model of PDIG based microgrid and design of complementary stabilizer using ICA

The generalized Heffron–Phillips model (GHPM) for a microgrid containing a photovoltaic (PV)-diesel machine (DM)-induction motor (IM)-governor (GV) (PDIG) has been developed at the low voltage level. A GHPM is calculated by linearization method about a loading condition. An effective Maximum Power Point Tracking (MPPT) approach for PV network has been done using sliding mode control (SMC) to maximize output power. Additionally, to improve stability of microgrid for more penetration of renewable energy resources with nonlinear load, a complementary stabilizer has been presented. Imperialist competitive algorithm (ICA) is utilized to design of gains for the complementary stabilizer with the multiobjective function. The stability analysis of the PDIG system has been completed with eigenvalues analysis and nonlinear simulations. Robustness and validity of the proposed controllers on damping of electromechanical modes examine through time domain simulation under input mechanical torque disturbances.     

Quantitative calibration of radiofrequency NMR Stark effects

Nuclear magnetic resonance (NMR) Stark responses can occur in quadrupolar nuclei for an electric field oscillating at twice the usual NMR frequency (2ω(0)). Calibration of responses to an applied E field is needed to establish nuclear spins as probes of native E fields within material and molecular systems. We present an improved approach and apparatus for accurate measurement of quadrupolar Stark effects. Updated values of C(14) (the response parameter in cubic crystals) were obtained for both (69)Ga and (75)As in GaAs. Keys to improvement include a modified implementation of voltage dividers to assess the 2ω(0) amplitude, |E|, and the stabilization of divider response by reduction of stray couplings in 2ω(0) circuitry. Finally, accuracy was enhanced by filtering sets of |E| through a linear response function that we established for the radiofrequency amplifier. Our approach is verified by two types of spectral results. Steady-state 2ω(0) excitation to presaturate NMR spectra yielded C(14) = (2.59 ± 0.06) × 10(12) m(-1) for (69)Ga at room-temperature and 14.1 T. For (75)As, we obtained (3.1 ± 0.1) × 10(12) m(-1). Both values reconcile with earlier results from 77 K and below 1 T, whereas current experiments are at room temperature and 14.1 T. Finally, we present results where few-microsecond pulses of the 2ω(0) field induced small (tens of Hz) changes in high-resolution NMR line shapes. There too, spectra collected vs |E| agree with the model for response, further establishing the validity of our protocols to specify |E|.     

Fabrication of functional poly(thiophene) electrode for biosensors

Three-type polymer electrodes such as poly(Th), poly(Th-AP) and poly(Th-AP-TAA) were fabricated, respectively, by electro-oxidative polymerization of thiophene (Th), mixture of Th and 2-aminophenol (AP), and mixture of Th, AP and 3-thiopheneacetic acid (TAA) on the surface of indium tin oxide (ITO) glass by cyclic voltammetry (CV). The polymer electrodes were electrodeposited by cycling the potential between -1.0 and +2.5V in acetonitrile containing 50mM tetrabutylammoniumhexafluorophosphate (TBAF(6)P). The surface morphology of polymer electrodes was investigated by scanning electron microscopy (SEM) and atomic force microscopy (AFM) analysis. The surface morphology of the poly(Th) showed typical roughness and fractal-like growth patterns, and the morphologies of poly(Th-AP) and poly(Th-AP-TAA) were dramatically changed. The water contact angle at the poly(Th-AP-TAA) (23 degrees ) is lower in comparison to poly(Th) (47 degrees ). The functional groups (-OH) and carboxylic acid (-COOH) group play an important role. Horseradish peroxidase was loaded onto poly(Th-AP-TAA) surface and used to test the sensing of H(2)O(2).     

Experimental and theoretical determination of low electron energy loss spectra of Ag and Ru

We show the experimental and calculated q-dependent low energy loss electron energy loss spectrum of Ru and Ag. The spectra were calculated within the time-dependent density-functional theory including local-field effects. For Ag, the momentum transfer was parallel to the (110) direction. For Ru the three main directions (010), (110) and (001) were investigated. The agreement between theory and experiment is very good for Ag and for momentum transfers parallel to the (001) direction of Ru. For momentum transfers parallel to the in-plane directions (110) and (010) the agreement for Ru is not satisfactory, which could be attributed to relativistic effects or to strong localization of the 4d states of Ru.     

锑,铕,铈,铒同位素丰度和原子量测量

用已知化学纯度的两种浓缩同位素通过化学计量,配制人工合成样品,用来测量质谱计系统误差校正系数,校正用该仪器测量的来自地球不同地域矿样和试剂样品中锑（Ｓｂ）、铕（Ｅｕ）、铈（Ｃｅ）、铒（Ｅｒ）四种元素天然同位素丰度比,求出这些元素同位素丰度的真值。用该真值和已知的上述四元素核素质量,计算得原子量分别为１２１．７５９７（７）Ｓｂ、１５１．９６４４（９）Ｅｕ、１４０．１１５７（８）Ｃｅ、１６７．２５９１（９）Ｅｒ     

Assessment of selected properties of LDPE composites reinforced with sugar beet pulp

This study measured the effect of sugar beet pulp (SBP) and maleated polyethylene (MAPE) concentrations on the properties of low density polyethylene (LDPE) composites. SBP concentration has significantly increased density, thickness swelling (TSW), water absorption (WA), flexural strength (FS), tensile modulus (TM) and flexural modulus (FM) of composites while reducing tensile strength (TS), elongation at break (EatB) and impact strength (IS). Presence of MAPE has improved TSW, WA, TS, FS, TM and FM. However, EatB and IS were slightly worsened by MAPE use. Composites showed two main decomposition peaks; one coming from SBP (360–368 °C) and the second one from LDPE degradation (484–490 °C). SEM images showed improved dispersion of SBP. The composites has provided less than 2% weight loss and classified as ‘very durable material’ against white-rot and brown-rot fungi attack. Through this study, potential utilization of SBP in LDPE matrix was demonstrated.     

沱茶中茶多酚的分析与鉴定

用索氏提取器以三氯甲烷为萃取剂,在95 ℃下从沱茶中提取茶多酚。用旋转蒸发器将滤液浓缩,有机相中加入三氯甲烷(V(三氯甲烷):V(浓缩液)=3:1)将咖啡因萃取分离、去除。水相中加入乙酸乙脂(V(乙酸乙酯):V(水)=3:1)将沱茶提取物萃取分离。以硅胶G作填充剂,以乙酸乙酯(V(乙酸乙酯):V(乙醚)=4:1)为洗脱剂进行柱层析。用傅里立变换-红外光谱法(FT/IR)测定沱茶提取物待测组分的红外光谱图,提供官能团的有关信息。确定待测组分的可能结构;应用气相色谱-质谱法(GC/MS)对其进行分析与鉴定,由电子电离源质谱(EI/MS)获得待测组分的质谱图和相关数据,进而对子离子裂解途径和特征离子进行辅助解析,确证待测组分为茶多酚。为开发利用沱茶提供了科学依据。