A chiral thioureido acid as an effective additive for enantioselective organocatalytic Michael additions of nitroolefins

A novel and effective organocatalytic system consisting of pyrrolidinyl-thioimidazole and a chiral thioureido acid efficiently catalyzed the asymmetric Michael addition reactions of ketones to nitroolefins to afford the adducts with high diastereoselectivities (up to 99 : 1) and excellent enantioselectivities (up to 99% ee).     

First-principles determinations and investigations of the electronic absorption and third-order polarizability spectra of electron donor-acceptor chromophores tetraalkylammonium halide/carbon tetrabromide

Calculations on donor-acceptor molecular pairs of tetraalkylammonium halide/carbon tetrabromide complexes are provided to investigate structure/property-related linear and nonlinear optical properties by using the time-dependent density functional theory technique coupled with the sum-over-states method. The calculated energies of the first allowed electronic transition decrease, and the nonresonant third-order polarizabilities at the THG, EFISHG, and DFWM optical processes increase progressively from [DBU-H+Br-.CBr(4) to [NPr(4)Br.CBr(4)] to [NMe(4)Br.CBr(4)]. The obtained electronic absorption spectra show a progressive red shift with increasing donor strength from Cl to I for [NR(4)h.CBr(4)] (h = Cl, Br, and I). The charge transfers from the halogen donor to the carbon tetrabromide acceptor make significant contributions to the electronic absorption spectra in the low-energy zone and the third-order polarizabilities in the nonresonant frequency region. The counterion indirectly affects the electronic absorption and third-order polarizability spectra through the interactions between the donor and acceptor.     

船载系泊状态下基于原子重力仪的绝对重力测量

重力场是反映地球质量分布及变化的重要参数,动态重力测量在地质调查、地球物理、资源勘探等领域有着重要应用.目前动态重力测量均基于相对测量原理,动态相对重力仪存在零点漂移问题,影响其测量性能.动态绝对重力仪可以为相对重力仪提供同步同址校准,解决其长漂问题,因此备受关注.本文基于原子重力仪和惯性稳定平台,搭建了一套船载绝对重力动态测量系统,并在船载系泊状态下开展了绝对重力动态测量实验.经评估,船载系泊环境下的重力测量灵敏度为16.6 mGal/Hz^-1/2,1000 s积分时间内重力测量的分辨率可达0.7 mGal.通过两周的绝对重力测量,评估了系统的稳定性.为了评估绝对重力的动态测量精度,将船上测量点与码头高精度绝对重力基准点的绝对重力值进行了比较,两点之间的绝对重力值差及其不确定度评估结果为(–0.072±0.134)mGal.本文结果为海洋相对重力仪的同时同船校准提供了一种新方案.     

基于前驱体Pb(OH)I溶液法制备FAPbI3太阳能电池

甲脒铅碘因具有高热稳定性和较窄的禁带宽度而受到广泛关注。本工作使用羟基碘化铅代替传统碘化铅、氯化铅,通过一步溶液法制备介孔甲脒铅碘钙钛矿太阳能电池,研究退火温度对材料的结晶性、覆盖层形貌和器件的效率等方面的影响。较之传统的溶液法工艺,基于羟基碘化铅制备的甲脒铅碘薄膜表现出更为优异的热稳定性能。最终在AM 1.5G一个太阳光照明下,得到了5.8%的光电转化效率,其中短路电流为18.6mA·cm^-2,开路电压为0.67V,填充因子为0.47。     

Synthesis,Structure and Photoluminescent Property of a Cd-organic Complex [Cd（L）_2（pbda）]_n

A new complex,[Cd(L)2(pbda)]n(1,L = 3-(2-pyridyl)-4-(p-methoxyphenyl)-5-(2-thienyl)-1,2,4-triazole,H2pbda = 1,4-benzenedicarboxylic acid),has been hydrothermally prepared and characterized by single-crystal X-ray diffraction,IR spectroscopy,elemental analysis and PXRD.The complex crystallizes in monoclinic,space group P21/c with a = 8.2929(9),b = 21.668(2),c = 10.9940(11) ,β = 90.242(2)o,V = 1975.5(4) 3,Z = 2,C44H32N8O6S2Cd,Mr = 945.30,Dc = 1.589 g/cm3,μ = 0.721 mm-1,S = 1.097,F(000) = 960,the final R = 0.0590 and wR = 0.1045 for 3846 observed reflections(I > 2σ(I)).In the title complex,the rigid bridging pbda2-ligands utilize oxygen atoms of carboxylate groups to coordinate with Cd(II) atoms to form one-dimensional chains which are further interlinked into a three-dimension framework via the intermolecular weak interactions.Photoluminescence study revealed that complex 1 exhibits strong fluorescent emission band in the solid state at room temperature.     

Detection and characterization of cholesteryl ester hydroperoxides in oxidized LDL and oxidized HDL by use of an Orbitrap mass spectrometer

Oxidation of cholesteryl esters in lipoproteins by reactive oxygen species yields cholesteryl ester hydroperoxides (CEOOH). In this study, we developed a novel method for identification and characterization of CEOOH molecules in human lipoproteins by use of reversed-phase liquid chromatography with an hybrid linear ion trap-Orbitrap mass spectrometer (LC-LTQ Orbitrap). Electrospray ionization tandem mass spectrometric analysis was performed in both positive-ion and negative-ion modes. Identification of CEOOH molecules was completed by use of high-mass-accuracy (MA) mass spectrometric data obtained by using the spectrometer in Fourier-transform (FT) mode. Native low-density lipoproteins (nLDL) and native high-density lipoproteins (nHDL) from a healthy donor were oxidized by CuSO(4), furnishing oxidized LDL (oxLDL) and oxidized HDL (oxHDL). No CEOOH molecules were detected in the nLDL and the nHDL, whereas six CEOOH molecules were detected in the oxLDL and the oxHDL. In positive-ion mode, CEOOH was detected as [M + NH(4)](+) and [M + Na](+) ions. In negative-ion mode, CEOOH was detected as [M + CH(3)COO](-) ions. CEOOH were more easily ionized in positive-ion mode than in negative-ion mode. The LC-LTQ Orbitrap method was applied to human plasma and six species of CEOOH were detected. The limit of detection was 0.1 pmol (S/N = 5:1) for synthesized CEOOH.     

食品中苏丹红Ⅰ和辣椒红的表面增强拉曼散射(SERS)光谱与激发-发射矩阵荧光光谱鉴别

利用表面增强拉曼散射(SERS)光谱及激发-发射矩阵(EEM)荧光光谱对食品中非法添加剂苏丹红Ⅰ和合法食品添加剂辣椒红进行了定性分析和检测. SERS光谱结果表明, 苏丹红Ⅰ在低波数区域分子的扭转振动信号增强比较明显; 而辣椒红在1521和1158 cm^-1处拉曼信号增强效果比较明显; EEM荧光光谱结果表明, 苏丹红Ⅰ的乙醇溶液在P₁(λ_ex=285 nm, λ_em=345 nm)和P₂(λ_ex= 335 nm, λ_em=548 nm)处有2个明显的荧光特征峰; 而辣椒红的乙醇溶液有3个特征荧光峰, 分别为P₁(λ_ex=545 nm, λ_em=580 nm), P₂(λ_ex=560 nm, λ_em=665 nm)和P₃(λ_ex=608 nm, λ_em=672 nm).     

8-或6-(3-氯苯甲酰)香豆素衍生物的合成、表征、生物活性及与牛血清白蛋白的相互作用

合成了2个新化合物7-羟基-8-(3-氯苯甲酰基)-4-甲基香豆素(1)和7-羟基-6-(3-氯苯甲酰基)-4-甲基香豆素(2). X射线单晶衍射分析表明, 2个化合物的晶体同属于单斜晶系, P2₁/c空间群, 化合物1: a=1.21527(14) nm, b=1.01550(12) nm, c=1.5045(2) nm, β=112.377(2)°, V=1.7169(4) nm³, D_c=1.396 g/cm³, Z=4, F(000)=752, R₁=0.0415, wR₂=0.0981[I>2σ(I)], S=1.063; 化合物2: a=2.0168(2) nm, b=0.76229(12) nm, c=2.25497(17) nm, β=123.987(6)° , V=0.8745(6) nm³, D_c=1.454 g/cm³, Z=8, F(000)=1296, R₁=0.0604, wR₂=0.1384[I>2σ(I)], S=0.948. 抗菌实验结果表明, 2个化合物对大肠杆菌(E. coli)、 枯草杆菌(B. subtilis)和金色葡萄球菌(S. aureus) 均有中等程度的抑制作用; 体外抗氧化实验结果表明, 2个化合物对超氧阴离子自由基(O₂^-·)、 羟基自由基(·OH)和二苯代苦味肼基自由基(DPPH·)均有良好的清除能力. 采用荧光光谱法研究了不同温度下2个化合物与牛血清白蛋白(BSA)的相互作用, 结果表明, 2个化合物对BSA 的荧光猝灭均属于静态猝灭; 热力学数据表明, 化合物1(ΔH>0, ΔS>0, ΔG<0)与BSA主要以疏水作用力相结合, 化合物2(ΔH<0, ΔS<0, ΔG<0)与BSA主要以氢键或范德华力相结合; BSA与化合物1和化合物2间的距离分别为2.59和2.38 nm, 说明2个化合物与BSA 之间可能发生了非辐射能量转移.     

PDA5500Ⅱ直读光谱仪在线分析中的应用

介绍了PDA5500直读光谱仪在线分析低合金钢中常规五元素(碳、硅、锰、磷和硫)的分析方法,讨论了分析过程中的分析条件、设置、校正方法及得出的结果评判,配合唐山钢铁集团公司一钢厂150吨转炉的生产控制,结果令人满意。     

Au-Ag三角纳米环单层膜的原位转化制备及 SERS效应

利用模板牺牲氧化还原反应将自组装在基片上的三角板银纳米粒子(边长约为79.2 nm)与氯金酸溶液作用进而原位转化形成三角纳米环. 通过紫外-可见(UV-Vis)光谱实时监测基片上银三角板纳米粒子在反应不同阶段的消光特性; 扫描电子显微镜(SEM)显示了银三角板纳米粒子转化过程的形貌变化; 利用X射线光电子能谱(XPS)对其成分进行分析. 表征结果表明, 三角纳米环的成分为Au-Ag合金或复合物; 随着基片与氯金酸溶液作用时间的增加, 自组装膜的表面等离子体共振峰逐渐红移; Au-Ag三角环状纳米粒子的平均壁厚度从29.3 nm缩小至16.2 nm. 以4-巯基苯胺(4-ATP)为探针分子研究了该Au-Ag三角环状纳米粒子单层膜的表面增强拉曼(SERS)活性. 自组装单层膜基底的SERS信号随着Au-Ag三角纳米环平均壁厚度的增加逐渐增强.