广州新建住宅空气中甲醛的分析

利用SKC便携式甲醛检测器对一新建住宅群 (7栋252套 )室内空气的甲醛含量进行抽样测定,测定结果在0.070～0.373mg/m3之间 ,大部分超出了美国和加拿大的0.1×10 -6(φ)的室内空气质量标准,以及我国的0.080mg/m3 的标准,分析结果表明木制品是室内装修甲醛污染的主要来源     

The Preparation of Perovskite Nano Powder by Sol-gel from DTPA and the Mechanism of Thermal Decomposition

Dy0.8Sr0.2FeO3 nano powder, a synthetic oxide, is made by sol-gel method from metal nitrate and diethylenetriaminepentaaeetic acid (DTPA), and the processing parameters are optimized.The process of the preparation, thermal decomposition and the property of the powder are studied by TG-DTA, IR, TEM, and XRD. The diameter of the average grain is about 70 nm. This new technique can be used in the preparation and the studying of ha‘no materials in the complex oxide system.     

Synthesis and Crystal Structure of a Novel Supramolecular Compound [Mg(H_2O)_6](C_(16)H_(11)O_4SO_3)_2·10H_2O

IntroductionMolecularpolymerwithonedimensionalormultidimen sionalstructureassemblingthroughhydrogenbondsisanim portantresearchcontentinthesupramolecularchemistryandcrystalenginnering .1,2 Withthedevelopmentofnewtypefunctionalmaterialssuchasmolecularmagnetic ,selectedcatalysis ,reversiblecatalysis ,reversiblehost guestmolecular(ion)exchangeetc.,3themoleculardesignandsynthesishavealreadyattractedconsiderableattentioninsupramolecu larsystem .Thesupramolecularcomplexesandorganiccom poundscontainin…     

Synthesis,DNA binding,nuclease activity and cytotoxic studies of a wheel‐shaped octanuclear copper(II) complex based on 1,2,4‐triazole

The antitumor activity shown by many platinum complexes has produced a strong interest in research of new organometallic compounds. Among the metal compounds synthesized and tested, copper compounds have received considerable attention because of their cytotoxic activity against solid tumors. A novel wheel‐shaped octanuclear copper(II) complex with a 1,2,4‐triazole derivative ligand formulated as [Cu₈L₄](ClO₄)₈?11H₂O ( 1 ) (L = 3,5‐bis((bis(2‐hydroxylethyl)amino)methyl)‐4 H‐1,2,4,‐triazole‐4‐amine) has been synthesized and structurally characterized. In 1 , eight Cu atoms are linked through 1,2,4‐triazole units and alkoxide bridges to form a centrosymmetric octanuclear Cu(II) metallomacrocycle. The interaction of complex 1 with calf thymus DNA has been studied using UV absorption, fluorescence and circular dichroism spectroscopies, viscosity measurements and cyclic voltammetry. The apparent binding constant (k_app) value for 1 is 1.59 × 10⁵ M^?1. Furthermore, complex 1 displays efficient oxidative cleavage of supercoiled DNA in the presence of external agents, the rate constant for the conversion of supercoiled to nicked DNA being 2.67 × 10^?5 s^?1. Interestingly, cytotoxicity studies on the MCF‐7 human breast cancer cell line show that the IC₅₀ value of 1 is less than that of cisplatin for the same cell line, revealing that it has the potential to act as an effective metal‐based anticancer drug. Copyright © 2016 John Wiley & Sons, Ltd.     

C_4O_4~(m-)(m=0,1,2,3,4)的从头算研究——1.平衡几何和相对稳定性

在RHF(基离子在UHF和ROHF)/6-31G,6-31G~*和6-31 G水平优化得到C_4O_4~(m-)(m=0,1,2,3,4)的平衡几何构型,发现从中性分子(C_4O_4)到负4价离子(C_4O_4~(4-))经历了一个由非芳香性到芳香性再到反芳香性的结构变化过程,它们的相对稳定性为C_4O_4~->C_4O_4~(2-)>C_4O_4>C_4O_4~(3-)>C_4O_4~(4-).     

The preparation of functionalized single walled carbon nanotubes as high efficiency DNA carriers

The positively charged single walled carbon nanotubes (SWNTs~ ) were prepared by conjugating with-CONH-C_6H_(12)-NH_3~ . The double strand DNA(dsDNA) chains were loaded onto SWNTs~ via the electrostatic interactions.SWNTs~ shows improved loading efficiency (353.5μg/mg) toward dsDNA compared with that of charged free single walled carbon nanotubes (SWNTs) (82.9μg/mg).     

Prototropic tautomers of 5‐methylcytosine and enthalpy changes of their protonation,deprotonation, and deamination: Hybrid density functional B3LYP study

Molecular and thermodynamic properties such as geometric parameters, dipole moments, vibrational frequencies, the first ionization potentials, relative tautomerization energies, and tautomeric equilibrium constants of all prototropic tautomers of 5‐methylcytosine have been studied at the hybrid density functional level B3LYP/6‐31+G(d,p). The methylation on the C5 atom does not lead to significant geometric deformation of the pyrimidine structures of the corresponding tautomers of cytosine, which maintains the similar stability order. The tautomeric species 2‐oxo‐4‐amino [T(0)], 2‐hydroxy‐4‐amino [T(1‐2s) and T(1‐2t)], and trans‐2‐oxo‐4‐imino [T(3‐4t)] are predominated in the gas phase. The zwitterionic conformers of tautomerism [T(1‐4)] and protonation [P(4), P(1‐2s‐4), P(1‐2t‐4), and P(1‐3‐4)] are investigated for the first time due to their close relationship with deamination during genetic repair. Enthalpy changes (Δ_rH) of protonation, deprotonation, and deamination are calculated for these tautomeric species at room temperature; it is noted that the relative enthalpies [δ(ΔH)] of the tautomers are rationalized well in terms of a second‐order polynomial of the sum of the mean Δ_rH values of protonation and deprotonation processes. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002     

基于统计学模型的真空绝缘堆闪络概率计算分析

对比了几种不同类型的过电压因子下绝缘堆闪络概率的特点, 考虑了多层均压及圆周渡越时间后得到的闪络概率更能反映绝缘堆耐压水平;简化计算统计学经验公式中矩阵可保持绝缘堆闪络概率计算值准确性并减少过电压因子的静电场计算次数。分析在固定间隙距离下绝缘环个数与电压峰值及电场强度峰值的关系, 计算结果表明:存在最优绝缘环个数承受最高电压峰值与电场强度, 承受最大工作场强的绝缘环个数下, 工作电压幅值已降低很多。在选择绝缘环个数时应综合考虑, 该计算方法可应用于工程绝缘结构设计中合理选取绝缘环个数。     

Spin-Tunneling Time in Ferromagnetic/Semiconductor/Ferromagnetic Three-Terminal Heterojunction in the Presence of Rashba Spin-Orbit Coupling

We study theoretically the transmission coefficients and the spin-tunneling time in ferromagnetic/semiconductor/ferromagnetic three-terminal heterojunction in the presence of Rashba spin-orbit interaction, in which onedimensional quantum waveguide theory is developed and applied. Based on the group velocity concept and the particle current conservation principle, we calculate the spin-tunneling time as the function of the intensity of Rashba spinrblt coupling and the length of the semiconductor. We find that as the length of the semiconductor increases, the spintunneling time does not increase linearly but shows behavior of slight oscillation, i;brthermore, with the increasing of the soin-orbit coupling, the spin-tunneling time increases.