金属离子协同效应对血红蛋白分子荧光光谱的影响

本文采用荧光光谱法对血红蛋白(Hb)与Zn^2 、Cu^2 、Ag^ 三种离子的单一离子及混合离子的相互作用进行了研究。结果表明,Zn^2 对Hb有较强的荧光增强作用,Cu^2 具有较强的荧光淬灭作用,而Ag^ 有较弱的荧光淬灭作用;在二元金属离子与Hb的混合体系中,由于金属离子与Hb之间存在竞争配位作用或离子之间相互制约及协同效应,使混合体系中Hb的荧光光谱变化较单一金属离子有明显的差异。     

季铵阳离子与无机阴离子对铁的缓蚀协同效应

在酸性介质中,季铵阳离子与无机阴离子对铁具有明显的缓蚀协同效应,阴离子的表面活性越强,对协同效应的贡献越大,阳离子的结构对协同效应同样有着明显的影响。本文采用电化学方法仔细地研究了硫酸溶液中四丁基铵阳离子(TBA~+)和十六烷基吡啶阳离子(HDP~+)与SCN~-及I~-对铁的缓蚀协同效应。     

氢键的协同效应与超加和性的理论研究

采用3种DF方法和MP2方法,6-31++G**基组对线性和环状(HF)_n分子簇(n=1~5)进行了详细的理论研究.计算结果表明,在(HF)_n分子簇(n=1~5)中氢键有很强的协同效应和超加和性.另外,计算结果也表明在同样的计算精度下,DF方法可以大大地节省计算时间.因此,采用其中的一种DF方法计算了更大的线性(HF)_n分子簇(n=6,9,12,18,24),发现 (HF)_n分子簇氢键的协同效应和超加和性在n>12时明显收敛,n=24时已接近极限,此时的计算结果与实验中得到的固体HF数据符合较好.     

一种基于协同效应的肼荧光探针及其在细胞成像中的应用

开发了一种基于协同效应的新型肼荧光探针.通过在发色团上引入两种不同的识别位点,双识别位点的协同效应使得该探针对肼具有良好的专一性和灵敏度,检测限可达0.05~10.0μmol·L^-1.此外,该探针还可用于细胞(Bt-474)中肼的检测.     

咪唑啉衍生物与硫脲之间的缓蚀协同效应研究

应用失重法、动电位扫描法、X射线光电子能谱(XPS)研究了咪唑啉缓蚀剂和硫脲复配后对碳钢在CO2盐水溶液中的缓蚀协同作用.实验表明,咪唑啉和硫脲之间存在着良好的协同效应,二者复合后对CO2腐蚀有较好的抑制作用.经XPS检测,试样表面吸附膜有N、S元素存在,而且,于接近基体处,S元素含量相对较高;而在溶液界面处,则N元素含量较高.据此推断缓蚀剂和硫脲在钢样表面可能形成"包含络合物",从而使缓蚀剂膜更加致密,缓蚀效果也更好.     

双功能受阻胺与紫外线吸收剂并用的协同效应研究

本文用IR、UV、ESR、TLC等方法研究了新型的双功能受阻胺光稳定剂,Tinuvin-144 [2-(4′-羟基-3′,5′-二叔丁基)苄基-2-正丁基丙二酸五甲基哌啶醇酯]与紫外线吸收剂,UV-531(2-羟基-4-正辛氧基二苯甲酮)和UV-327(2-[2′-羟基-3′,5′-二叔丁基]-5-氯 代苯并三唑)并用体系对聚丙烯光稳定化的并用效应。结果表明,Tinuvin-144与UV-531,UV-327并用时均具有良好的协同效应,144对531,327或531,327对144的光分解均具有相互的保护作用。结果还表明,144与531或327无论在模拟体系或聚丙烯中,在诱导期内均不存在促使他们消耗的化学反应,提出了协同作用的机理。     

多重非共价作用及其协同效应在吸附分离和药物控释方面的应用

从热力学推导可知,分子与较大的实体间通过多重非共价作用的结合,其结合能大于这些作用力分别单独作用时结合能的加和,即多重非共价作用之间存在协同效应。本文讨论了多重非共价作用(如疏水作用、离子作用、氢键等)及其协同效应在吸附体系和药物控释体系的设计中的应用,一些单独作用时对结合可能没有贡献的非共价作用(如水介质中的氢键),与其它作用同时发生时对结合可能有贡献。合理利用多重非共价作用及其协同效应不仅能提高吸附量和药物负载量,而且还能调控不同吸附质间的吸附选择性和药物的控制释放性能。     

光电协同效应降解饮用水中邻氯酚的机理与动力学

要 在集成光解电解一体化反应器中, 以邻氯酚(2-CP)为模型污染物, 通过产物和动力学分析详细探讨了光电复合作用的协同效应机理, 建立了光电复合作用的动力学模式. 表观动力学常数的对比表明复合协同作用对于总有机碳(TOC)的去除具有显著的协同效应. 研究表明, 光电复合作用在研究条件下对污染物的降解具有多层次、多途径的互补效应, 降解反应的途径不止是单独的光解与电解途径的简单累加, 而是通过新的作用途径组合构成光电协同效应. 通过紫外光辐射激发和定向直流电场作用控制电极中毒和污染物分子的激发态及其迁移趋势, 从而大大提高了降解反应的效率. 通过光电复合作用能够触发构成高级氧化的多种自由基链反应, 从而取得水中有机污染物的快速、完全的矿化. 动力学分析表明, 光电协同作用在溶液中形成的羟基自由基(OH·)反应是去除TOC的主要途径.     

CO_2体系中咪唑啉季铵盐与十二烷基磺酸钠之间的缓蚀协同效应

采用失重法、电化学阻抗谱(EIS)、极化曲线、X射线光电子能谱仪(XPS)及扫描电子显微镜(SEM)研究了CO2饱和的3.5%NaCl腐蚀介质中,咪唑啉季铵盐(IAS)与十二烷基磺酸钠(SDSH)对Q235钢的缓蚀协同效应.结果表明,IAS与低浓度SDSH在腐蚀介质中具有较好的缓蚀协同效应,且当二者以1:1(50 mg·L-1:50 mg·L-1)的浓度比例复配时,协同效应最明显,缓蚀率为88.5%;而IAS与高浓度SDSH间会产生拮抗效应.本文通过建立合理的吸附模型,阐述了协同效应及拮抗效应的机理.SDSH与IAS在Q235钢表面的吸附过程均为放热的自发过程,前者符合Frumkin吸附模型,后者符合Temkin吸附模型.单独使用较高浓度的SDSH对Q235钢也有较好的缓蚀作用,缓蚀率接近90%.     

钙作为合金元素对铝在碱溶液中的缓蚀作用及其与酒石酸盐的协同效应

通过集气法、极化曲线和电化学阻抗谱研究了在铝中添加合金元素钙对其在碱 溶液中的缓蚀作用及其与酒石酸盐的协同效应。实验结果表明，铝电极的腐蚀速率 随钙含量的增加而减小。溶液中不含酒石酸盐时，钙对电极反应的阴极过程有显著 的抑制作用，对阳极过程作用不明显；而当溶液中含有酒石酸盐时，阴极过程和阳 极过程均被显著抑制。阻抗谱的解析结果还表明，钙离子或酒石酸钙络离子是通过 减小反应物在活性位上的反应速率而起缓蚀作用的，它们可能属于界面型缓蚀剂而 非成相型缓蚀剂。     

蛋白质荧光标记中协同效应的高效液相色谱

以牛血清白蛋白和胰岛素为研究对象, 经1,5-I-AEDANS衍生后, 采用高效液相色谱(HPLC)进行分离分析, 发现两者的衍生存在明显的协同作用.     

质谱法研究鸭梨最佳施肥期肥料N的平衡及其效应

本实验利用质谱法探讨鸭梨最佳施肥期肥料N的平衡及其效应。数据分析表明,秋施肥较春施和夏施有利于植株吸收更多的肥料N;促进树体间的协调生长;能够最有效地提高土壤的供肥能力对于肥料N的损失最少。从秋施、春施、夏施三个施肥期的综合效果看,梨树施肥应以秋施为主、春施为辅。     

Theoretical study of hydrogen bonded clusters of water and fulminic acid

Ab initio and density functional calculations are used to analyze the interaction between a molecule of fulminic acid with 1, 2, 3, and 4 molecules of water along with a 2:2 complex at B3LYP/6-31+G(d,p) and MP2/6-311++G(d,p) computational levels. Cooperative effect (CE) in terms of stabilization energy of clusters are calculated and discussed as well. CE is increased with increasing cluster size of studied clusters. Red shifts of H–C stretching frequency for complexes involving HCNO as H-donor are predicted.     

铁和铈共掺杂二氧化钛中的协同效应

The co-doping of iron and cerium into TiO2 was studied by means of X-ray diffraction, Raman spectroscopy, UV-Vis diffuse reflectance spectroscopy and X-ray photoelectron spectroscopy. when separately doping via the sol-gel method, iron was introduced in the framework of anatase TiO2 whereas cerium was not; interestingly, both iron and cerium were introduced in the framework when co-doping by the sol-gel method. The co-doped TiO2 behaves much more intense surface hydroxyl concentration than the separately-doped and pure TiO2. This observation demonstrates for the first time a cooperative effect in the co-doping of transitional metals in the framework of TiO2.     

Theoretical study of hydrogen bonded clusters of water and cyanic acid: Hydrogen bonding in terms of the molecular structure

Ab initio and density functional calculations were used to analyze the interaction between a molecule of cyanic acid (HOCN) and up to 4 molecules of water at the B3LYP/6-311++G(d,p) and MP2/6-311++G(d,p) computational levels. The cooperative effect (CE) is increased with the increasing size of the studied clusters. Red shifts of the H–O stretching frequency for complexes involving HOCN as an H-donor were predicted. The strength of the hydrogen bonds in terms of molecular structures could be deduced from a comparison of HOCN–H₂O with HCNO–H₂O, HONC–H₂O and HNCO–H₂O HB clusters. The atom in molecules (AIM) method was used to analyze the cooperative effects on topological parameters.     

Solvent and Substituent Effects on the Protonation of Anilines in Dioxane–Water Mixtures

Protonation constants of a number of mono-substituted anilines were determined potentiometrically in 0, 20, 30, 40, 50, and 60% (v/v) dioxane–water mixtures at (25.00 ± 0.0.02)°C at an ionic strength of 0.1 mol-dm^–3 in sodium perchlorate. The data from the potentiometric titrations were evaluated using the BEST computer program. The trends in the values of the protonation constants of anilines were explained in terms of the nature of substituent and the solute–solvent and solvent–solvent interactions. Furthermore, the effects of the substituents on the basicity of aniline, the additivies of these effects, and the applicability of the Hammett equation to the behavior of these substituents are discussed.     

Theoretical Simulations of Kinetic Isotope Effects on Decarboxylation of 3-Carboxybenzisoxazole

Kinetic isotope effect values on the decarboxylation of 3-carboxybenzisoxazole have been computed using the second-order Kleinert's variational perturbation theory in the framework of Feynman's path integrals along with the potential energy surface obtained at the MP2/6-31+G(d) level. Good agreement with the experimental data was obtained, demonstrating that this novel computational approach for computing KIE values of organic reaction is a viable alternative to the traditional method employing the Bigeleisen equation and harmonic vibrational frequencies. Compared with the experimental measurements, consideration of anharmonicity and tunneling effects can significantly improve the calculated KIE values, reducing the root-mean-square deviation from 1.19 % for traditional method to 0.20 % for path-integral method.     

Cooperative trial studies on the analysis of ethyl carbamate using capillary gas chromatography

A design for cooperative study of analytical methods is described which involves the analysis of spiked samples and evaluation of the results using a linear regression technique. Two examples are described involving the study of ethyl carbamate in whisky at levels from 40–170 μg/L and in beer at levels <1–20 μg/L. Most participating laboratories used capillary gas chromatography with variations in sample preparation and detection methods. Acceptability criteria were defined as: intercept ±2 standard deviations of the group mean, slope 0.9 to 1.1, individual analyses of duplicates within ±10% of the mean and correlation coefficient better than 0.99. In the whisky trial, four of the seven laboratories taking part met these criteria, while for the beer trial all of the laboratories taking part were sufficiently close to these standards to be considered satisfactory given that the analyses were being performed close to the detection limit of the methods.     

PBO聚合物紫外吸收光谱中环境因素影响的理论研究

芳杂环液晶高分子聚对亚苯基苯并二噁唑（PBO, poly(p-phenylene-2,6- benzobisoxazole)）的共轭平面结构赋予其光电性能而备受关注.实验结果表明其光电性能受其所处环境状态影响. 通过量子化学计算研究发现,PBO无论固态还是溶液状态的最大紫外吸收均较其本征值有所红移.对PBO二聚体模型以及其在强质子酸中所具有的质子化形态模型的紫外吸收光谱计算模拟的结果表明,PBO聚集态时的分子间相互作用,以及溶液中质子化效应均导致红移.质子化模型所得紫外吸收光谱能很好地阐释溶液中具有精细结构实测的紫外吸收光谱.     

A Combined Theoretical Calculation and Hirshfeld Surface Analysis of Cooperative Non‐covalent Interactions in the Crystal Packing in [Cu(L1)2(EDA)]

The monomeric complex [Cu(L1)₂(EDA)] ( I ) [L1 = 2,4‐dinitrobenzoic acid, EDA = ethylenediamine), was solved in orthorhombic space group (Pbca) and characterized by elemental analysis, IR spectroscopy, powder XRD analysis, and single‐crystal X‐ray crystallography, in addition to photoluminescence and thermal stability investigation. The Cu²⁺ ion is connecting with two L1 through monodentate mode of coordination and two nitrogen atoms from EDA. I is associated through cooperative non‐covalent interactions, which are also responsible for the strengthening of the molecular assembly and organize it into a supramolecular 2D motif. Hirshfeld surface analysis was also applied to investigate the cooperative non‐covalent supramolecular interactions and the results were compared with the single‐crystal X‐ray diffraction data. To get clear insights into the both species, electronic properties such as HOMO‐LUMO, electronic chemical potential and other derived parameters were also highlighted using DFT calculations at M06‐2X/ 6‐31G** level of theory. The observed photoluminescence of complex I arises mainly from an excited LLCT state with small MLCT contributions (from Cu²⁺ to the unoccupied p orbital of L1). The presented work exhibits another example of the utility and prosperity of such kinds of subtle information and features especially, and for complex I at molecular level, generally.