A Trial of Variational-Cumulant Expansion on Simple Ising Model With Second Order Phase Transition

The standard variational-cumulant expansion (VC) combined with a scheme for the enumeration of connected diagrams is employed to study the simple Ising model with the second-order phase transition. This model is evaluated to the 5th order approximations. A comparison with the 2-dimensional exact results shows that thermodynamic quantities converge rather slowly to the exact values in the intermediate region. A strict analytical calculation of the critical temperature with the 5th order approxinlation both for J_i and cumulant expansion suggests that VC chn achieve rather high standard accuracy if the variational parameters J_i could be determined up to higher degrees of corrections rather than the first one. Anomalies are found for U, C and M at extremely low temperature. A detailed study of M implies that thermodynamic formulae should be carefully chosen in VC approach so as to avoid these anomalies.     

噻唑烷类配体的手性结构及其在催化苯乙酮不对称硅氢化反应中的应用研究

用分级结晶或柱层析方法对2-(2-吡啶基)-4-羧甲基-1,3-噻唑烷(A)及2-甲基-2-(2-吡啶基)-4-羧甲基-1,3-噻唑烷(B)两种手性配体进行提纯,分别考察了其与[Rh(COD)Cl]₂制备的在位催化剂催化苯乙酮的不对称硅氢化反应,发现只有噻唑烷环上的C4位手性中心对催化反应结果有影响,其C2位手性中心在Rh(1)催化下发生了快速差向异构化反应.     

具有时间分辨能力的强流电子束束剖面测量系统

 高能强流电子束的束参数测量是加速器研制过程中重要的一项测量工作,由于光学渡越辐射具有时间响应快、分辨率高等特点而被用于测量电子束的具有时间分辨能力的束剖面、发散角、能量等多个参数;通过电子束束参数的时间分辨测量则能够了解电子束产生、输运中的问题,非常有利于加速器的研究与调试。一种具有时间分辨能力的、利用光学渡越辐射进行高能强流电子束束斑测量的系统在中国工程物理研究院被建立起来,并在12 MeV LIA的电子束束斑的测量中用于电子束传输研究,该系统拍摄图像的间隔时间最小为10 ns,最小的曝光时间为3 ns,具有一次可以拍摄8幅图像的能力,并获得了12 MeV LIA约100 ns内相应的时间分辨的束斑变化情况,观察到了一些过去未观察到的现象,为加速器的研究提供了又一个新测试方法。     

光学渡越辐射测量中能量分辨精度分析

 基于光学渡越辐射原理的用于高能强流电子束束流参数在线测量及诊断系统,具有时间响应快、分辨率高等特点,可以测量电子束的束剖面、发散角、能量等多个参数。分析了测量系统的结构参数（包括了透镜的焦距、成像面位置、CCD像元尺寸）对电子束能量测量精度的影响,并在理论上模拟了电子束的发散角的影响。还根据系统数据的特点,阐述了数据噪声对能量测量结果精度的影响,指出了光学渡越辐射测量中电子束能量分辨精度受到多种因素的影响,需要在数据处理时考虑修正。     

Multispectral Plasmon of Anisotropic Core-shell Gold Nanorods@SiO2: Dual-band Absorption Enhancement with Coupling Dye Molecules

Direct evidence of effects of surface plasmon resonance(SPR) of gold nanorods(GNRs) on dual-band light absorption enhancement with coupling dye molecules was reported by introducing gold nanorod@SiO₂(GNR@SiO₂) core-shell nanoparticles into a photoelectric conversion system. GNR with asymmetric shape had unusual anisotropic SPR[transversal surface plasmon resonance(TSPR) and longitudinal surface plasmon resonance(LSPR)]. The excellent SPR of GNR made it a promising candidate as enhancing light absorption material to increase power conversion efficiency(PCE). The PCE was improved nearly 17.2% upon incorporating GNRs, mostly due to the increase in J_sc, while V_oc and FF were unchanged. The improvement was mostly contributed by the SPR of the GNRs with coupling of N719. And there was also a complementary to N719 in visible light range. Therefore, SPR is an effective tool in improving the photocurrent and consequently enhancement of PCE. The TSPR and LSPR effects of GNRs on light harvesting were reflected in the increased monochromatic incident photon-to-electron conversion efficiency(IPCE). We also utilized finite-difference time-domain(FDTD) to investigate the light coupling of GNRs with TiO₂. Compare to the base anode, the IPCE of optimized electrode showed significant improvement and peaks broadening at 500-600 nm and 610-710 nm. We got an increase in overall conversion efficiency from 6.4% to 7.5%.     

耦合相对转动非线性动力系统的稳定性与近似解

研究了一类含三次非线性耦合项的相对转动非线性动力系统的动力学行为. 建立了具有非线性弹性力、广义摩阻力耦合项的系统动力学方程. 运用多尺度法求解谐波激励下耦合非自治系统的近似解,通过讨论系统的主共振和内共振特性,分析了耦合项对系统响应的影响. 应用奇异性理论研究了主振稳态响应分岔方程的稳定性,得到了系统的转迁集和分岔曲线的拓扑结构. 关键词： 相对转动 非线性耦合动力系统 奇异性理论 稳定性     

Search for chiral bands in A ～ 110 neutron-rich nuclei

High spin states in A ～ 110 neutron-rich 106Mo, 110Ru and 112Ru nuclei have been reinvestigated by measuring the prompt γ-rays from the spontaneous fission of 252Cf. Two similar sets of bands are observed to high spins in each of three nuclei. Through analyzing of characters of the band structures, the chiral doublet bands are suggested in 106Mo, 110Ru and 112Ru.     

Gamma Vibrational Bands and Chiral Doublet Bands in A≈100 Neutron-rich Nuclei

The level structures of neutron-rich ~(105)Mo,~(106)Mo,~(108)Mo and 110Ru nuclei in A≈100 region have been carefully investigated by coincidence measurements of the prompt γ-rays populated in the spontaneous fission of ~(252)Cf with the Gammasphere detector array.In 105Mo,one-phonon K =9/2 and two-phonon K=13/2 γ-vibrational bands have been identified.In ~(108)Mo,one-phonon γ-vibrational band is expanded and two-phonon γ-vibrational band has been identified.Two similar sets of bands in ~(106)Mo and ~(110)Ru are observed to high spins,which have been proposed as the soft chiral γ-vibrational bands.The characteristics for these γ-vibrational bands and chiral doublet bands have been discussed.     

煤气化中NO_x及其前驱物释放规律研究

采用U型管反应系统,研究了氧浓度、气流速率和气化温度对神木煤气化过程中NO_x及其前驱物的释放规律.研究发现:气化时生成的HCN和NH_3总量比热解时大幅下降,表明O_2的引入抑制了H自由基的可获得性.随着氧浓度的增加,NO的收率先减后增,而NO_2收率几乎没有变化.氧浓度较低时,生成的高浓度CO阻止了挥发分氮向NO的转化.气流速率对含氮气相产物释放影响各不相同.低温气化产物以NO_2和HCN为主,NO_2主要来自进样期挥发分的缓慢氧化,而高温气化产物中的NH_3的生成主要来源于焦炭氮.     

丁基罗丹明B-表面活性剂体系荧光光谱法测定人血清蛋白

研究了阳离子染料丁基罗丹明 B在阴离子表面活性剂十二烷基苯磺酸钠存在时的吸收光谱和荧光性能 ,发现随蛋白质浓度增大荧光强度逐渐增强 ,在一定范围内增强程度与蛋白质浓度成正比 ,据此建立了一种测定人血清蛋白的新方法 ,线性范围 0— 6 .0 mg·L-1 ,检出限为 4 .4 μg/ L。用于合成样品测定 ,结果令人满意。