Interfacial electrical properties of DNA-modified diamond thin films: intrinsic response and hybridization-induced field effects

We have investigated the frequency-dependent interfacial electrical properties of nanocrystalline diamond films that were covalently linked to DNA oligonucleotides and how these properties are changed upon exposure to complementary and noncomplementary DNA oligonucleotides. Frequency-dependent electrical measurements at the open-circuit potential show significant changes in impedance at frequencies of >10(4) Hz when DNA-modified diamond films are exposed to complementary DNA, with only minimal changes when exposed to noncomplementary DNA molecules. Measurements as a function of potential show that at 10(5) Hz, the impedance is dominated by the space-charge region of the diamond film. DNA molecules hybridizing at the interface induce a field effect in the diamond space-charge layer, altering the impedance of the diamond film. By identifying a range of impedances where the impedance is dominated by the diamond space-charge layer, we show that it possible to directly observe DNA hybridization, in real time and without additional labels, via simple measurement of the interfacial impedance.     

A theoretical study of electronic excited states of photosynthetic reaction center in Rhodopseudomonas viridis

The electronic singlet vertical excited states of photosynthetic reaction center (PSRC) in Rhodopseudomonas (Rps.) viridis were investigated by ZINDO and INDO/S methods. The effects of the interactions of pigment-pigment and pigment-protein on the electronic excitations were examined. The calculation results showed that the interactions of pigment-pigment and pigment-protein play an important role in reasonably assigning the experimental absorption and circular dichroism (CD) spectra of PSRC in Rps. virids. By comparing the theoretically computed excited states with the experimental absorption and CD spectra, satisfactory assignments of the experimental spectroscopic peaks were achieved.     

EDTA—Cu配合物用于还原糖的测定

首次报道了应用ＥＤＴＡ（乙二胺四乙酸二钠盐）－铜配合物（ＥＣ）测定还原糖的分光光度法，结果表明，ｐＨ４～１１时ＥＣ的最大吸收波长为７３２ｎｍ，在ＨＣＯ－３ＣＯ２－３缓冲介质中，配合物ＥＣ的吸光度与还原糖在０７７～１６１ｍｇ（六碳糖）范围内有很好的线性关系，相关系数大于０９９８，样品测定回收率在９５％～１０５％之间。该法试剂易得、性质稳定，操作方便，灵敏度较高，取样量少于５ｍＬ。     

铕和镧与吡啶－2，6－二甲酸配合物的NMR研究

合成了稀土铕、镧与吡啶－２，６二甲酸形成的二元配合物及铕与邻菲罗啉和吡啶－２，６二甲酸形成的三元配合物。经元素分析确定该配合物的组成分别为二元：Ｎａ３［Ｅｕ（ＤＰＣ）３］·２Ｈ２Ｏ，Ｎａ３［Ｌａ（ＤＰＣ）３］·２Ｈ２Ｏ；三元：ＮａＥｕ（ＤＰＣ）２·ｐｈｅｎ·４Ｈ２Ｏ。用核磁共振研究了配体与稀土的配位方式，讨论了诱导效应、屏蔽效应及稀土离子的顺磁性对配合物化学位移和ＮＭＲ谱图的影响。ＮＭＲ研究表明，三种配合物具有相似的对称结构和相同的化学位移变化规律。吡啶－２，６二甲酸中的羧酸以单齿配位（整个分子为三齿配位），二元配合物中，铕和镧的配位数均为９，三元配合物中，铕的配位数最低为８。     

肉桂酸类分子非线性光学效应的理论研究

计算了一系列肉桂酸（苯基丙烯酸）类化合物的二阶非线性光学系数，系统地研究了取代基的电子性质和取代位置对其非线性光学性质的影响，并且探讨了该类化合物的饱和取代效应．研究表明，该类化合物的非线性光学性质与其分子结构有着密切的关系．     

Two New ent-Kaurane Diterpenoids from Isodon xerophilus

In continuation of our research on diterpenoids in the Isodon species, several newcompounds"' were obtained from the leaves oflsodon xerophilus (C. Y. Wu et H. W. Li)H. Hara (Labiatae), a perennial shrub native to Yunnan province. Further fractionation ofthe EtOAc extract led to the isolation of tWo new enl-kauranoids, xerophilusin E (l) andxerophilusin F (2). This paper deals with the structUral elucidation of the newcompounds.Xerophilusin E (l), a minor constitUent, was obtained as p…     

硅氧聚合度对细胞毒性的影响

本文采用家兔肺泡巨噬细胞(AM)存活率和细胞过氧化脂质(LPO)值为测定指标,研究了硅氧的聚合度对其细胞毒性的影响。结果表明:各种聚合度的硅氧都有一定的细胞毒性,聚合度愈大,细胞毒性也愈大。胶体SiO_2的粒径增大,其细胞毒性降低。十硅酸盐及粒径小于5nm的硅溶胶的细胞毒性大于α-石英。聚合度小于6的低聚硅酸及其盐、粒径18nm以上的硅溶胶以及硅胶H的毒性皆小于α-石英。本实验细胞存活率降低和过氧化脂质值升高的趋势基本一致,这表明硅氧可能主要与细胞表面膜作用,膜上磷脂等表面活性物质被氧化和变性,从而导致细胞损伤。     

Simple sulfone-bridged heterohelicene structure realizes ultraviolet narrowband thermally activated delayed fluorescence,circularly polarized luminescence,and room temperature phosphorescence

Due to narrowband emission and high quantum efficiencies, polycyclic aromatic heterocycles with multi-resonance thermally activated delayed fluorescence (MR-TADF) properties have recently gained considerable attention in the organic optoelectronic field. Albeit their great promise in the full visible region covering from blue to red, MR-TADF emitters with ultraviolet emission have been rarely reported. Through locking the two ortho-positions of a triphenylamine core by sulfone groups, a simple polycyclic aromatic heterocycle, BTPT, was facilely constructed, exhibiting 368 nm ultraviolet emission with a narrow full width at half maximum (FWHM) of 33 nm. Its neat film exhibited distinct TADF property with a main emission peak at 388 nm. Noteworthily, the enantiomeric crystals of BTPT not only demonstrated significant circularly polarized luminescence (CPL) with large luminescence dissymmetry factor in the 10^?3 order but also displayed obvious room temperature phosphorescence (RTP). The relationship between this innovative helical unit and unique photophysical properties, including ultraviolet MRTADF, CPL, and RTP, was reasonably revealed.

     

Biradicals/zwitterions from thermolysis of enyne-isocyanates. Application to the synthesis of 2(1H)-pyridones, benzofuro[3,2-c]pyridin-1(2H)-ones, 2,5-dihydro-1H-pyrido[4,3-b]indol-1-ones, and related compounds

Thermolysis of benzannulated enyne-isocyanates 13 and enyne-isocyanates 36 and 37 promoted the cycloaromatization reactions to generate in situ O,4-didehydro-2-hydroxyquinolines and O,4-didehydro-2-hydroxypyridines, respectively, as reactive intermediates. These cycloaromatized intermediates could be captured either as biradicals and/or as zwitterions depending on the nature of the substituent at the alkynyl terminus. The intermediate derived from cycloaromatization of 13a bearing a phenyl substituent could be regarded as biradical 14, which then abstracts hydrogen atoms from gamma-terpinene leading to 2(1H)-quinolinone 15. Alternatively, the same intermediate could also be regarded as zwitterion 14', which then undergoes an initial hydride abstraction from gamma-terpinene followed by protonation to produce 15. The presence of a 2-phenylethyl substituent in 13b and 37a or a 2-methylphenyl substituent in 37b also allowed the resulting intermediates to be captured intramolecularly either as biradicals or as zwitterions, producing 2(1H)-quinolinone 19, 2(1H)-pyridone 39, and benzopyranopyridine 43, respectively. On the other hand, with a 2-methoxyphenyl, a 2-(dimethylamino)phenyl, or a 3-methoxypropyl substituent, the chemical behavior of the cycloaromatized adduct could be best accounted for in terms of a zwitterionic intermediate leading to benzofuro[3,2-c]quinolin-6(5H)-one (20), 5,11-dihydro-11-methyl-6H-indolo[3,2-c]quinolin-6-one (25), benzofuro[3,2-c]pyridin-1(2H)-one 44, 2,5-dihydro-2,5-dimethyl-1H-pyrido[4,3-b]indol-1-one 46, and related compounds. Interestingly, thermolysis of 37f bearing a 2-(methoxymethyl)phenyl substituent at the alkynyl terminus produced the unexpected benzopyranopyridine 56 as the major product in a process involving the cleavage of the bond between the methoxyl oxygen and the adjacent methylene carbon. The efficiency and selectivity of the cycloaromatization reaction could also be enhanced by the introduction of 1.1 to 10 equiv of dimethylphenylsilyl chloride to the reaction mixture to capture the resulting zwitterion.