Low-temperature growth and photoluminescence property of ZnS nanoribbons

At a low temperature of 450 degrees C, ZnS nanoribbons have been synthesized on Si and KCl substrates by a simple chemical vapor deposition (CVD) method with a two-temperature-zone furnace. Zinc and sulfur powders are used as sources in the different temperature zones. X-ray diffraction (XRD), selected area electron diffraction (SEAD), and transmission electron microscopy (TEM) analysis show that the ZnS nanoribbons are the wurtzite structure, and there are two types-single-crystal and bicrystal nanoribbons. Photoluminescence (PL) spectrum shows that the spectrum mainly includes two parts: a purple emission band centering at about 390 nm and a blue emission band centering at about 445 nm with a weak green shoulder around 510 nm.     

Silicone-modified starch/protein microparticles: protecting biopolymers with a hydrophobic coating

Silicone-coated starch/protein (human serum albumin, HSA) microparticles were prepared by precipitation of a starch/HSA/DMSO/water (water-in-oil) emulsion into acetone containing a silicone: the silicone polymer was either unfunctionalized (SiMe₃ terminated, PDMS) or functionalized at its termini with Si(OEt)₃ groups (TES-PDMS). The microparticles of approximate diameter 2–7 μm were highly hydrophobic with advancing contact angles 115°. Over several minutes, however, the contact angle decreased to ca. 40–70°. Soxhlet extraction with water led to degradation of the microparticles, irrespective of the nature of their silicone coating, as evidenced by release of the protein from them. Intraperitoneal (IP) or gastric administration of the two different particles to mice, however, showed a clear difference between the two silicones. The microparticles coated with either PDMS or TES-PDMS led to very different immune responses. Oral administration of the microparticles prepared with functionalized silicone elicited a significant production of antibodies, whereas the particles prepared with the unfunctionalized silicone (PDMS) were only weakly active. By contrast, the IP results demonstrated that particles coated with PDMS elicited an immune response that was established much more rapidly than with the particles modified with TES-PDMS. It is proposed that the TES-PDMS forms a physically adhering film or covalent bond to the protein molecules, which serves to protect the microparticle from biological degradation in the gut and/or facilitates the microparticle/protein interaction with the immune system.     

一种新的库仑微水滴定仪的设计方法

在传统微库仑滴定仪原理的基础上，利用８７５１单片机和微机，采用对电解电流时间调制的方法以及测量精度为准则判断滴定终点，从而大大地提高了仪器的测量精度和重复性。     

Alcohol/water-soluble porphyrins as cathode interlayers in high-performance polymer solar cells

Three alcohol/water-soluble porphyrins,Zn-TPy PMe I:zinc(II)meso-tetra(N-methyl-4-pyridyl)porphyrin tetra-iodide,ZnTPy PAd Br:zinc(II)meso-tetra[1-(1-adamantylmethyl ketone)-4-pyridyl]porphyrin tetra-bromide and Mn Cl-TPy PAd Br:manganese(III)meso-tetra[1-(1-adamantylmethyl ketone)-4-pyridyl]porphyrin tetra-bromide were employed as cathode interlayers to fabricate polymer solar cells(PSCs).The PC71BM([6,6]-phenyl C71 butyric acid methyl ester)and PCDTBT(poly[N-9″-hepta-decanyl-2,7-carbazole-alt-5,5-(4′,7′-di-2-thienyl-2′,1′,3′-benzothiadiazole)])-blend films were used as active layers in polymer solar cells(PSCs).The PSCs with alcohol/water-soluble porphyrins interlayer showed obviously higher power conversion efficiency(PCE)than those without interlayers.The highest PCE,6.86%,was achieved for the device with Mn ClTPy PAd Br as an interlayer.Ultraviolet photoemission spectroscopic(UPS),carrier mobility,atomic force microscopy(AFM)and contact angle( )characterizations demonstrated that the porphyrin molecules can result in the formation of interfacial dipole layer between active layer and cathode.The interfacial dipole layer can obviously improve the open-circuit voltage(Voc)and charge extraction,and sequentially lead to the increase of PCE.     

ICP-AES法测定茶叶中As,Cd,Ni,Pb等元素的含量

目的对样品前处理、酸度及茶叶中共存元素干扰的影响等因素进行探讨,方法用微波消解前处理样品,ICP-AES法同时测定茶叶中铅(Pb)、砷(As)、镉(Cd)、镍(Ni)等元素含量。结果该法的回收率在84.5%～115%之间,精密度RSD均小于9%,结论该法能满足茶叶测定要求。     

原子荧光光谱法测定白砂糖和红糖中硒含量

目的：测定白砂糖和红糖中硒含量为研制富硒糖提供科学依据。方法采用微波消解-原子荧光光谱法测定白砂糖和红糖中硒含量。结果在确定的最佳仪器条件下,原子荧光光谱法测定白砂糖和红糖中硒的检出限为0.063μg · L-1;白砂糖硒的RSD为2.28％,红糖的RSD为2.13％;白砂糖回收率为103.4％,红糖回收率为99.7％。结论该法具有方法简便、快捷、准确等优点,适用于白砂糖和红糖中硒含量测定。     

Substitution reactions at silicon under strongly acidic conditions: Ligand metathesis between methyltrichlorosilane and octamethylcyclotetrasiloxane

A study of the reactions between methyltrichlorosilane (MeSiCl₃) and octamethylcyclotetrasiloxane (D₄) in the presence of trifluoromethanesulfonic acid (HOTf) showed that nucleophilic substitution in CHCl₃ solution at the trifunctional silicon was surprisingly slow in comparison with the rate of equilibration/polymerization of D₄. The reaction rate at MeSiCl₃ was significantly faster with water present and faster still in THF. In these reactions, there was no evidence for SiOH groups (²⁹Si NMR), even in the presence of excess water. The overriding criterion for relative reactivity toward nucleophilic substitution under strongly acidic conditions is the relative leaving group ability of the groups on silicon. Once MeSiCl₃ begins to participate in the redistribution reactions, mono- 3 and tri- 5 , but not di-substituted 4 systems are formed (MeSiCl_3−x(D_nSiMe₂Z (Z = OTf, Cl))_x, x = 1, 3), likely through an intramolecular reaction. The mechanisms of nucleophilic substitution at silicon under these conditions are discussed.     

改性SiO2载体对邻菲咯啉钌荧光特性及氧敏感荧光膜性能的影响

为提高极性荧光指示剂Ru(dpp)₃Cl₂在非极性硅橡胶中的分散性,以沉淀白炭黑、气相白炭黑和甲基MQ树脂,载负荧光指示剂Ru(dpp)₃Cl₂,再填充到二甲基硅橡胶(PDMS)中,制备氧敏感荧光膜.以分光光度计和荧光光谱仪,研究载体种类对Ru(dpp)₃Cl₂的吸附性、荧光特性及氧敏感荧光膜性能的影响.白炭黑载负Ru(dpp)₃Cl₂的荧光发射光谱相对其稀溶液约红移20 nm.载体表面的甲基可减弱SiO₂载体对Ru(dpp)₃Cl₂分子的吸附性和相互作用,减少荧光发射光谱的红移12 nm,提高荧光强度近10倍.白炭黑有助改善Ru(dpp)₃Cl₂在PDMS中的分散性和氧敏感荧光膜的荧光输出和猝灭比,尤以MQ树脂的效果最为显著.     

应用ICP-MS测定市售红葡萄酒中重金属元素的含量

目的随着对葡萄酒功效的认识,它逐渐成为普通人喜欢的饮品,所以对葡萄酒中各种成分的研究也成了热点。方法借助先进的ICP-MS技术对4种葡萄酒中的各种重金属和微量元素进行测定。结果金属元素质量浓度由高到低顺序为:As,Cr,Pb,Cd,As最高不超过0.5μg.mL-1,结论符合国家食品卫生标准。     

SBA-15负载Pd催化剂的制备及其在Heck反应中的应用研究

利用水热反应制备了表面离子液体功能化的SBA-15介孔材料,在丙酮溶液中与氯化钯反应,然后使用水合肼在乙醇中还原.测试了这种催化剂在Mizoroki-Heck反应中的催化活性.与直接负载在SBA-15上的钯催化剂相比,这种表面修饰的介孔SBA-15负载催化剂表现出更高的催化活性、可回收性和反应稳定性.氮气吸脱附实验和小角XRD衍射实验表明,在合成中,材料的介孔性能并没有被破坏.透视电镜也表征了该材料的表面形貌.最后,Mizoroki-Heck反应表明该催化剂具有很高的催化活性,且循环五次后,其催化活性降低并不明显.