How can the Cross-Link Adducts Formed by Novel Trans Platinum Drug be Influenced by Hydrogen Bond

A systematic quantum chemical characterization of intrinsic structure, energies and spectral properties of all the studied cross-link adducts formed by the novel trans platinum with thiazole ligand has been carried out at B3LYP/6-31G^＊ level of theory with the Lanl2dz pseudo potential basis set for the Pt atom. Special attention has been paid to the relative stability of these complexes and the factors that probably alter the order of the relative stability. The important influence of hydrogen bond on the structures, the energies and the spectral property was revealed. Other factors that contribute to relative stability including solvation effect, entropy and electronic delocalization energy were taken into account. The stability energy of the whole complex, and the interaction energy between two purine bases and the [Pt-（NH3）thiazole]^2＋ group were adopted to study the interplay among subsystems and their contribution to relative stability of all the studied cross-link model. Finally, basic spectral properties of these complexes including H（8） chemical shifts of all the studied complexes and the VCD （vibrational circular dichroism） spectra of two pairs of GG chelate enantiomers, were provided in order to define the structure of the most possible duplex bearing novel trans platinum drug lesions.     

Total luminescence intensity (TLI) offers superior early oxidation detection in unstabilised polyethylene but is no better than FT-IR for stabilised polyolefins

In an earlier study, we have shown that chemiluminescence (CL) and the total luminescence intensity (TLI) method are highly sensitive to oxidation in degradable PE. In this study, stabilised PE and PP were characterised with CL in an inert (TLI) and in an oxygen atmosphere (CL-OIT) and the results were compared to those obtained by the commonly used techniques, FT-IR (carbonyl index (CI)) and thermal analysis (DSC-OIT). PE was aged at a low temperature (80 °C) and PP was aged at temperatures between 60 and 120 °C. Non-Arrhenius behaviour was observed in the oxidation of PP. This showed the importance of aging at a low temperature to obtain realistic results. TLI and CI of stabilised PP and most of the stabilised PE gave comparable results with the same sensitivity for oxidation detection. This was in contrast to our previous results for degradable PE. However, TLI of unstabilised PE showed earlier oxidation detection than CI, which agreed with our earlier results. TLI of PE had a higher sensitivity than CL-OIT, and both TLI and CI of PP were sufficiently sensitive to detect the effect of aging at different temperatures, whereas DSC-OIT was not.     

Characterization of thermo-oxidative stability of polymer optical fibers using chemiluminescence technique

The thermo-oxidative stability of commercially available polymer optical fibers (POFs) and their components (cores and claddings) was investigated. All the bare POFs (core and cladding only) studied here were based on poly(methyl methacrylate) (PMMA) core. The fibers were exposed to 100 °C/low humidity for about 4200 h. Chemiluminescence (CL) technique was applied to investigate the thermo-oxidative stability and for measuring the transmission loss during exposure a prototype device called multiplexer was used. POFs exhibited variation in thermo-oxidative stability although they possessed identical core material PMMA. This was due to difference in the chemical compositions of claddings. Claddings were more susceptible to the thermo-oxidative degradation compared to cores. The thermo-oxidative degradation of both the cladding and the core was found in POFs as a result of climatic exposure. POFs showed an early drop-off followed by a slow decline of transmission. The early drop-off of transmission was attributed to physical changes like thermal expansion and the slow decline of transmission to chemical changes like oxidative degradation of POFs. A good linear relationship between optical transmission stability and thermo-oxidative stability of POFs was established from these studies.     

静电和疏水效应对TGEV主蛋白酶二聚体稳定性的影响

从TGEV 3CL蛋白酶二聚体结构出发,研究了TGEV 3CL蛋白酶二聚体单体之间的静电和疏水相互作用.蛋白质的静电相互作用通过有限差分方法求解Poisson-Boltzmann方程得到,疏水相互作用通过分析溶剂可及性表面模型得到.考察了不同pH值对TGEV 3CL蛋白酶二聚体静电和疏水相互作用的影响,在pH值为5.5～8.5时,二聚体静电相互作用能、静电去溶剂化能和疏水自由能都较小,表明在该条件下静电和疏水相互作用有利于二聚体的稳定存在,这符合实验结晶所需条件.pH值对静电去溶剂化能的影响大于疏水自由能,表明静电作用是造成强酸或强碱条件下二聚体不能稳定存在的主要原因.     

Dynamic Visualization of Free Radicals at Single Oxygen Bubbles using Chemiluminescence

The generation of free radicals is a key process in the formation and the collapse of the bubbles in water, however, the direct and dynamic observation of the radicals in this process at single bubbles has never been achieved. Here, the hydroxyl (OH^.) and oxygen (O₂^.−) radicals at single oxygen bubbles are continuously traced using chemiluminescence (CL), in which these radicals at the bubble react with the surrounding luminol in the solution emitting the light. Varied increase trends of luminescence are observed in the generation of a bubble, floating, short parking at the water/air interface and the final explosion, revealing the complexity in the distribution of radicals at the bubble unprecedentedly. Despite more radicals are observed at the bubble generated at a deep position under the water for the stabilization, almost the same amount of radicals are included in the bubbles that is independent on the water pressure during the production of the bubble. This rich information collected from the dynamic study of bubbles illustrates the complicated generation and distribution process of radicals at the bubbles, and will facilitate the understanding of the function about the bubbles.     

用偶合反应流动注射化学发光法测定矿样和水样中的痕量铊

将Tl(Ⅲ)置换Co(Ⅱ)-EDTA配合物中的Co(Ⅱ)与Co(Ⅱ)-鲁米诺-H2O2化学发光体系相偶合,建立了流动注射化学发光测定铊的新方法。本方法测定铊的线性范围为3.0×10-6~1.0×10-2mg/mL,检出限为1.0×10-6mg/mL。对1.0×10-4mg/mL的Tl(Ⅲ)标准溶液连续11次测定的相对标准偏差为2.0%。方法可用于矿样和水样中铊的测定。     

Mg掺杂AlGaN的特性研究

采用金属有机物化学气相淀积方法在Al2O3衬底上生长不同浓度Mg掺杂的AlxGa1-xN合金薄膜,并在750℃、N2气氛下对Mg进行热退火激活。用X射线衍射ω-2θ扫描计算确定样品的Al组分,发现Mg摩尔掺杂浓度和退火对Al组分均未产生明显影响。X射线衍射摇摆曲线与原子力显微镜扫描表明随Mg摩尔掺杂浓度增加,样品晶体质量下降,样品表面凹坑增加,但热退火对薄膜表面形貌有明显的改善。阴极射线发光测量发现带边峰强度随掺杂浓度增加而减弱,退火后样品的施主-受主对复合发射与导带受主的复合发射均有增强,验证了热退火对钝化受主杂质的激活作用,对实现高效AlGaN的p型掺杂具有重要意义。     

Ag(Ⅲ)配合物-鲁米诺化学发光体系用于文拉法辛的测定

Ag(Ⅲ)配合物在碱性介质中可氧化鲁米诺产生化学发光.实验发现,抗抑郁药物文拉法辛对该化学发光体系有显著的增敏作用.据此,结合流动注射技术,建立了化学发光测定文拉法辛的新方法.在优化条件下,方法的线性范围为0.1～2.0 mg·L-1,检出限(S/N=3)为0.05 mg·L-1,回收率为96％ ～ 105％,相对标准...     

纳米金催化Luminol-H_2O_2化学发光体系对异烟肼的测定

碱性条件下,纳米金对Luminol-H2O2化学发光体系有增敏作用,而异烟肼对该化学反应具有强烈的抑制作用。基于此,在优化化学发光反应条件的基础上,提出了一种测定异烟肼的新方法,并对其可能的化学发光机理进行了探讨。该方法测定异烟肼的线性范围为0.005~9.0 mg/L,检出限(3σ)为3.0μg/L,相对标准偏差为3.5%(n=11,ρ=0.2 mg/L)。该法已成功用于药物制剂中异烟肼含量的测定。     

Molecular dynamics simulation and density functional theory insight into the cocrystal explosive of hexaazaisowurtzitane/nitroguanidine

Theoretical methods involving molecular dynamics (MD) simulation and density functional theory were performed to investigate the different molecular ratios, mechanical Properties, structure, trigger bond, and intermolecular interaction of hexaazaisowurtzitane (CL‐20)/nitroguanidine (NQ) cocrystal explosive. Results of MD simulation show that CL‐20 and NQ packed in ratios of 1:1 present the larger binding energy and better mechanical properties than any other molecular ratios, which indicates 1:1 cocrystal can form the stable crystal structure. Shorter length and larger dissociation energy of trigger bond in composite structure than in isolated CL‐20 component suggests that the cocrystal may exhibit less sensitive than CL‐20. Analyses of atoms in molecules, reduced density gradient, and natural bond orbital confirm that intermolecular interactions are mainly derived from a series of weak hydrogen bond and strong vdW forces, involving of NH···O, CH···O, CH···N, O···N, and O···O. Additionally, composite structures of 2 and 3 bringing us more attractive performance will act as a key role in constructing of CL‐20/NQ cocrystal explosive. © 2015 Wiley Periodicals, Inc.