Efficient Intersystem Crossing in the Tröger's Base Derived From 4-Amino-1,8-naphthalimide and Application as a Potent Photodynamic Therapy Reagent

Intersystem crossing (ISC) was observed for naphthalimide (NI)-derived Tröger's base, and the ISC was confirmed to occur by a spin-orbital charge-transfer (SOCT) mechanism. Conventional electron donor/acceptor dyads showing SOCT-ISC have semirigid linkers. In contrast, the linker between the two chromophores in Tröger's base is rigid and torsion is completely inhibited, which is beneficial for efficient SOCT-ISC. Femtosecond transient absorption (TA) spectra demonstrated charge-separation and charge-recombination-induced ISC processes. Nanosecond TA spectroscopy confirmed the ISC, and the triplet state is long-lived (46 μs, room temperature). The ISC quantum yield is dependent on solvent polarity (8–41 %). The triplet state was studied by pulsed-laser-excited time-resolved EPR spectroscopy, and both the NI-localized triplet state and triplet charge-transfer state were observed, which is in good agreement with the spin-density analysis. The Tröger's base was confirmed to be a potent photodynamic therapy reagent with HeLa cells (EC₅₀=5.0 nm ).     

REE bound DNA in natural plant

The binding of rare earth elements (REEs) with nucleic acids in the leaves of fern Dicranopteris dichotoma (DD) has been studied by molecular activation analysis (MAA). The REEs bound DNA (REE-DNA) was obtained from the leaves of DD. The CTAB-based procedure was modified for extraction of total DNA. The purity of DNA was examined by UV spectroscopy. The DNA obtained was separated and determined by agarose gel electrophoresis further. Meanwhile, the contents of eight rare earth elements (La, Ce, Nd, Sm, Eu,Tb, Yb and Lu) in REE-DNA were detected by instrumental neutron activation analysis (INAA). The results showed that REE-DNA with higher purity could be extracted from plant using this method. It was also found that REEs were bound firmly with DNA in the leaves of DD. The molecular weight (MW) of REE-DNA band was about 22 kb in agarose gel electrophoresis.     

The lattice of idempotent distributive semiring varieties

A solution is given for the word problem for free idempotent distributive semirings. Using this solution the latticeL (ID) of subvarieties of the variety ID of idempotent distributive semirings is determined. It turns out thatL (ID) is isomorphic to the direct product of a four-element lattice and a lattice which is itself a subdirect product of four copies of the latticeL(B) of all band varieties. ThereforeL(ID) is countably infinite and distributive. Every subvariety of ID is finitely based. Project supported by the National Natural Science Foundation of China (Grant No. 19761004) and the Provincial Applied Fundamental Research Foundation of Yunnan (96a001z).     

弱阴离子交换硅胶整体柱的制备及其电色谱性能

采用溶胶-凝胶法,结合超分子模板技术,制备了一类新型有机-无机杂化硅胶离子交换整体柱。采用扫描电镜对整体柱的微观结构加以表征,证实孔结构均匀。将制备的弱阴离子交换整体柱应用于9种有机酸的分离,获得最高19万塔板数／米的柱效。探讨了pH值和有机改性剂浓度对分离的影响。     

离子色谱法测定米线中甲醛次硫酸氢钠的含量

建立了测定米线中甲醛次硫酸氢钠(甲醛次硫酸氢钠)的离子色谱方法。样品采用0.03 mol/L的Na OH溶液提取,离子色谱分离,KOH淋洗液洗脱,电导检测器测定。结果表明:方法的线性范围为2.0~50.0μg/m L,检出限为0.007μg/m L,测定结果的相对标准偏差不大于2.72%(n=6),加标回收率为91.4%~110.7%。该方法前处理简单、样品稳定性好、准确度高,具有较高的实用价值。     

石墨烯/钴镍双氢氧化物复合材料的制备及其超电容特性

采用氧化石墨(GO)还原法制备石墨烯(GNS),以氨水为沉淀剂,在石墨烯存在的情况下,通过Co²⁺和Ni²⁺化学共沉积的方法合成了石墨烯/钴镍双氢氧化物复合电极材料,采用红外光谱(FT-IR)、X射线衍射(XRD)、场发射扫描电子显微镜(FE-SEM)、比表面积测试(BET)等技术手段表征了产物的组成、结构和形貌,用循环伏安、恒电流充放电等测试方法对复合材料的电化学性能进行了研究。 研究发现,石墨烯纳米片均匀分散在钴镍双氢氧化物中,改善了钴镍双氢氧化物的传导性和结构稳定性。 电化学测试表明,在1 A/g的电流密度下,复合材料比电容高达2770 F/g,且循环500次后,比电容仍能保持93.4%,呈示该复合材料具有优异的电化学性能。     

Degradation and Pathways of Carvone in Soil and Water

Carvone is a monoterpene compound that has been widely used as a pesticide for more than 10 years. However, little is known regarding the fate of carvone, or its degradation products, in the environment. We used GC-MS (gas chromatography–mass spectrometry) to study the fate of carvone and its degradation and photolysis products under different soil and light conditions. We identified and quantified three degradation products of carvone in soil and water samples: dihydrocarvone, dihydrocarveol, and carvone camphor. In soil, dihydrocarveol was produced at very low levels (≤0.067 mg/kg), while dihydrocarvone was produced at much higher levels (≤2.07 mg/kg). In water exposed to differing light conditions, carvone was degraded to carvone camphor. The photolysis rate of carvone camphor under a mercury lamp was faster, but its persistence was lower than under a xenon lamp. The results of this study provide fundamental data to better understand the fate and degradation of carvone and its metabolites in the environment.     

机场蓄车池出租车司机的选择决策研究 ——以首都机场为例

随着中国全面小康的逐步实现,乘客下飞机后乘坐出租车回市区已经成为大多数人的选择.着眼出租车送客至机场后的情景,以出租车司机的盈利最大化为目标,讨论出租车司机的两种决策选择——决策A是留在机场蓄车池等待回城区的乘客,决策B是空载回城找生意.控制时间相同的条件下,用机场接客的订单金额来估计决策A的收益,用司机单位时间内平均收益乘以经营时长来衡量决策B的收益.以北京市首都国际机场为例,从数学模型的角度为出租车司机提供决策条件,有效实现司机利润最大化.     

Nanofabrication of 50 nm zone plates through e-beam lithography with local proximity effect correction for x-ray imaging

High resolution Fresnel zone plates for nanoscale three-dimensional imaging of materials by both soft and hard x-rays are increasingly needed by the broad applications in nanoscience and nanotechnology.When the outmost zone-width is shrinking down to 50 nm or even below,patterning the zone plates with high aspect ratio by electron beam lithography still remains a challenge because of the proximity effect.The uneven charge distribution in the exposed resist is still frequently observed even after standard proximity effect correction(PEC),because of the large variety in the line width.This work develops a new strategy,nicknamed as local proximity effect correction(LPEC),efficiently modifying the deposited energy over the whole zone plate on the top of proximity effect correction.By this way,50 nm zone plates with the aspect ratio from 4:1 up to 15:1 and the duty cycle close to 0.5 have been fabricated.Their imaging capability in soft(1.3 keV)and hard(9 keV)x-ray,respectively,has been demonstrated in Shanghai Synchrotron Radiation Facility(SSRF)with the resolution of 50 nm.The local proximity effect correction developed in this work should also be generally significant for the generation of zone plates with high resolutions beyond 50 nm.