MoBiTeO/SiO2催化剂在丙烷选择氧化反应中的表面结构重组

 考察了MoBiTeO/SiO2催化剂对丙烷选择氧化制丙烯醛的催化性能,并采用原位拉曼、 X射线衍射和X光电子能谱等技术研究了催化剂在反应过程中的结构重组及其对催化性能的影响. 实验结果表明,反应前, MoBiTeO/SiO2催化剂主要由Te多钼酸盐物种组成; 在570 ℃和C3H8/O2/N2=1.2/1/4的反应条件下, MoBiTeO/SiO2催化剂中的部分Te组分被深度还原为金属Te而流失,使部分Te多钼酸盐物种进行了结构重组形成了MoO3物种. Te多钼酸盐和MoO3之间的协同作用使催化剂的催化性能提高.     

免预硫化的加氢脱硫MoNiP/Al2O3催化剂的制备和表征

在Mo-Ni-P-O浸渍液中添加一定量的极性有机物如柠檬酸等,采用共浸渍法制备了一种不需预硫化和焙烧也具有较高加氢脱硫活性的MoNiP/Al2O3催化剂,并用N2吸附、程序升温还原、X射线光电子能谱、红外光谱和元素分析对催化剂进行了表征.结果表明,柠檬酸的添加削弱了金属组分与载体间的相互作用,有利于金属组分在载体表面的分散,且改善了催化剂的还原性,使催化剂在与含硫反应物料接触过程中自发硫化,从而有利于催化剂加氢脱硫活性的提高.     

b→cτ■ decay in supersymmetry with R-parity violation

In past years,several hints of lepton flavor universality(LFU)violation have emerged from the b→ct■,and b→sl~+l-data.More recently,the Belle Collaboration has reported the first measurement of the D* longitudinal polarization fraction in the B→D*τV decay.Motivated by this intriguing result,along with the recent measurements of RJ/Ψand τ polarization,we present the study of b→ct■ decays in supersymmetry(SUSY)with R-parity violation(RPV).We consider B→D(*)t■,Bc→ηct■,Bc→J/ψt■ and ∧b→∧ct■ modes and focus on the branching ratios,LFU ratios,forward-backward asymmetries,polarizations of daughter hadrons,and the τ lepton.The RPV SUSY was capable of explaining the RD(*) anomalies at the 2σ level,after taking into account various flavor constraints.In the allowed parameter space,the differential branching fractions and LFU ratios are largely enhanced by the SUSY effects,especially in the large dilepton invariant mass region.Moreover,a lower bound B(B~+→K~+vv)7.37×10~(-6) is obtained.These observables could provide testable signatures at the high-luminosity LHC and SuperKEKB,and correlate with direct searches for SUSY.     

Distinctive distribution of defects in CdZnTe:In ingots and their effects on the photoelectric properties

Photoelectric properties of CdZnTe:In samples with distinctive defect distributions are investigated using various techniques. Samples cut from the head(T04) and tail(W02) regions of a crystal ingot show distinct differences in Te inclusion distribution. Obvious difference is not observed in Fourier transform infrared(FTIR) spectra, UV–Vis–NIR transmittance spectra, and Ⅰ–Ⅴ measurements. However, carrier mobility of the tip sample is higher than that of the tail according to the laser beam induced current(LBIC) measurements. Low temperature photoluminescence(PL) measurement presents sharp emission peaks of D~0 X and A~0 X, and relatively large peak of D~0 X(or A~0 X)/D_(complexfor) T04, indicating a better crystalline quality. Thermally stimulated current(TSC) spectrum shows higher density of shallow point defects, i.e.,Cd vacancies, In_(Cd)~+, etc., in W02 sample, which could be responsible for the deterioration of electron mobility.     

Mode couplings of a semiconductor nanowire scanning across a photonic crystal nanocavity

The position-dependent mode couplings between a semiconductor nanowire(NW) and a planar photonic crystal(PPC) nanocavity are studied. By scanning an NW across a PPC nanocavity along the hexagonal lattice's Γ– M and M – K directions, the variations of resonant wavelengths, quality factors, and mode volumes in both fundamental and second-order resonant modes are calculated, implying optimal configurations for strong mode-NW couplings and light-NW interactions. For the fundamental(second-order) resonant mode, scanning an NW along the M – K(Γ– M) direction is preferred, which supports stronger light-NW interactions with larger NW-position tolerances and higher quality factors simultaneously. The simulation results are confirmed experimentally with good agreements.     

有机磷毒剂的电化学传感研究进展

有机磷毒剂是一类含磷（膦）酸或磷（膦）酸酯类高毒有机物及其衍生物的统称，能破坏正常神经传导，造成神经系统损伤，在军事行动和农业生产等方面的非常规使用给人类生存发展带来了严重威胁。电化学传感技术以其设备简便、灵敏度高、响应速度快等优点展现了实地传感有机磷毒剂的巨大潜力。总结了近几年有机磷毒剂的电化学传感相关研究报道，依据检测原理差异性将其分为4类：直接检测法、电化学酶法、电化学免疫法和电化学发光法。分析了各种方法的检测机理和优缺点；介绍了不同传感方法对工作电极修饰材料的要求；比较了不同电极修饰材料对方法检出限和线性范围的影响；阐述了电化学与生物技术结合检测有机磷毒剂的研究进展。电化学酶法和电化学免疫法具备选择性好和适用范围宽等优点，进而提出了纳米酶、纳米抗体和多维修饰材料结合传感检测含磷毒剂的新思路。     

压缩感知的远场亚波长声成像仿真

压缩感知算法可以利用信号的稀疏性较好地分辨出两个相距较远的目标,但是当两个目标相距较近时仅利用压缩感知算法,分辨性能较差;另外,当分辨目标为硬散射体时,由于偶极散射的影响,分辨性能也会变得较差。考虑到上述两个问题,该文提出了以下解决方案：针对第一个问题,该文将声学超透镜和压缩感知算法进行结合;针对第二个问题,该文提出在压缩感知算法中考虑偶极散射分量的影响。根据上述方案进行仿真,仿真结果证明了在加入声超透镜并考虑偶极散射以后,硬散射体目标在相距较近时实现了较好的分辨率。     

Ⅱ-Ⅵ族碲化物体单晶低温光致发光谱研究（英文）SCIEI北大核心CSCD

采用熔体法生长Ⅱ-Ⅵ族碲化物体单晶时,不同的生长条件及热经历过程会导致生长态晶体材料中,占主导的点缺陷类型存在较大的差异,进而影响了晶体的物理性能及器件的使用。低温光致发光(PL)谱作为一种无损检测方法,可以用于研究不同条件下生长的Ⅱ-Ⅵ族碲化物体单晶中的点缺陷和杂质的能级状态。对比富Te条件下生长的未掺杂ZnTe和CdTe晶体在8.6 K下的PL谱可以发现,电阻率较低的p型ZnTe晶体,其PL谱中,电子到中性受主复合发光峰(e,A^0)强度高于施主-受主对复合发光峰(DAP),而高电阻率阻n型CdTe晶体则刚好相反,这可能是由于生长速率及降温过程的热经历不同导致占主导的本征点缺陷类型不同造成的。按化学计量比生长的未掺杂CdZnTe晶体,其PL谱中自由激子发光峰(D^0,X)占主导,而(e,A^0)峰强度高于DAP峰,变温PL谱测试表明当温度高于15 K时,(e,A^0)峰与DAP峰逐渐叠加在一起。In掺杂导致在富Te条件下生长的CdZnTe晶体的PL谱中产生明显的A中心复合发光峰,与导带的能量差约为0.15 eV,主要与In补偿Cd空位形成的复合体[In_(Cd)^+V_(Cd)^(2-)]^-有关,且其强度与In掺杂元素的含量成正比。     

"一步法"合成多级孔SAPO-34分子筛

以TPOAC和硅溶胶为硅源,合成了多级孔SAPO-34分子筛,总比表面积达到649 m²·g^-1。详细考察了TPOAC和硅溶胶的配比对多级孔SAPO-34外比表面的影响,通过XRD、BET、SEM、NH₃-TPD等对其结构进行表征,结果表明多级孔SAPO-34的外比表面积可调变,晶体外观有较多缺陷位置,弱酸量减少,强酸位有变弱的趋势。在TPOAC与硅溶胶的投料比为3:2,晶化时间为10 d,投料比为n_Al2O3:n_P2O5:n_Si:n_TEAOH:n_H2O=1:0.9:0.5:2:60时,合成的多级孔SAPO-34的外比表面积达到最大,为100 m²·g^-1。     

基于荧光寿命机理的光纤温度传感器研究

为了实现恶劣环境下温度的测量,设计了一种基于荧光寿命机理的光纤温度传感系统.温度传感系统选用415 nm LED作为光源,以稀土荧光材料Y2O2S:Eu作为温度敏感材料,通过探测放大器和信号采集模块测量了敏感材料的荧光寿命,并由荧光寿命与温度的单调关系最终实现了温度的测量.采用油浴加热的方法进行温度实验,实验结果表明,温度传感系统在25~80℃实现了温度的测量,分辨率为0.5℃.