TiO_2-K_2SiO_3无机涂层对空间材料Ag的防护行为研究

在微波电离型原子氮（AO）源地面模拟设备中对空间材料Ag及TiO_2- K_2SiO_3无机涂层进行原子氧剥蚀效应试验。用扫描电镜（SEM）、光电子能谱（ XPS）、红外光谱（FT-IR）、X射线衍射光谱（XRD）和LAMBDA-9分光光度计，对在 模拟原子氧（AO）环境中Ag及在其表面涂覆的无机涂层，所发生的侵蚀与防护作用 进行了表征研究。AO对Ag表现了较严重的侵蚀作用，原来光亮如镜的表面形貌变得 粗糙，且失去光泽。而所施用的TiO_2-K_2SiO_3无机涂层，经AO辐照后，表面形貌 则变化甚少。实验表明，该涂层对AO辐照有较强的防护效果、较好的空间稳定性（ AO辐照前后Δα ≈ 0.024），能阻止AO对基材的侵蚀。     

TiO_2-K_2SiO_3无机涂层对空间材料Ag的防护行为研究

在微波电离型原子氧 (AO)源地面模拟设备中对空间材料Ag及TiO2 K2 SiO3 无机涂层进行原子氧剥蚀效应试验 .用扫描电镜 (SEM)、光电子能谱 (XPS)、红外光谱 (FT IR)、X射线衍射光谱 (XRD)和LAMBDA 9分光光度计 ,对在模拟原子氧(AO)环境中Ag及在其表面涂覆的无机涂层 ,所发生的侵蚀与防护作用进行了表征研究 .AO对Ag表现了较严重的侵蚀作用 ,原来光亮如镜的表面形貌变得粗糙 ,且失去光泽 .而所施用的TiO2 K2 SiO3 无机涂层 ,经AO辐照后 ,表面形貌则变化甚少 .实验表明 ,该涂层对AO辐照有较强的防护效果、较好的空间稳定性 (AO辐照前后Δαs≈ 0 .0 2 4) ,能阻止AO对基材的侵蚀 .     

聚乙烯/氧化铝复合材料形态、流变和力学性能

将聚乙烯（PE）和氧化铝（AO）熔融共混制得综合性能更好的PE/AO复合材料。通过对其进行流变分析、热力学性能分析、力学性能分析、导热性能分析和断面微观结构分析,探究AO质量分数对复合材料结构及性能的影响。结果表明,随着AO质量分数的增加,复合材料逐步转为脆性材料,其弹性模量、屈服强度、导热系数、储能模量同步增加;当AO质量分数为10%时,复合材料的断裂强度为18.2 MPa,综合性能最好。     

表面氨基高密度化介孔氧化硅的合成及其高效去除酸性橙7

以月桂酸为阴离子表面活性剂,3-胺丙基三乙氧基硅烷(APTES)为共结构导向剂,合成了高含量氨基功能化介孔氧化硅材料(AFMS)。以AFMS为吸附剂对溶液中酸性橙7(AO7)进行吸附,对影响AO7吸附效率的相关因素进行了详细研究,结果表明,溶液p H值及温度影响较大。吸附动力学表明,本研究中合成的AFMS对AO7的吸附速率极快。Sips吸附模型对吸附等温线模拟效果最好,从中可知AO7在样品D(由3.0 m L正硅酸乙酯及1.4 m L APTES合成)上的最大吸附量为1.26 mmol·g-1,远远高于相关文献报道的值。此外,通过吸-脱附循环实验证明,样品D具有良好的稳定性。     

酸性橙Ⅱ与牛血清白蛋白相互作用的电化学研究

以电化学法和光度法对酸性橙Ⅱ(AOⅡ)与牛血清白蛋白(BSA)的相互作用进行了研究。在pH 7.20的Tris-HCl缓冲溶液中,AOⅡ有一灵敏的还原峰,峰电位Ep约为-0.69 V(vs.SCE),加入BSA后AOⅡ还原峰电位正移,峰电流下降,据此建立了一种测定BSA的电分析方法。在优化条件下,峰电流下降值与BSA的浓度在5.0×10-8~1.0×10-5mol/L(r=0.9900~0.9939)范围内呈良好的线性关系,检出限为3.0×10-8mol/L。测定了AOⅡ与BSA的结合比和结合常数,并对结合反应机理进行了初步的探讨。     

表面氨基高密度化介孔氧化硅的合成及其高效去除酸性橙7

以月桂酸为阴离子表面活性剂,3-胺丙基三乙氧基硅烷(APTES)为共结构导向剂,合成了高含量氨基功能化介孔氧化硅材料(AFMS)。以AFMS为吸附剂对溶液中酸性橙7(AO7)进行吸附,对影响AO7吸附效率的相关因素进行了详细研究,结果表明,溶液pH值及温度影响较大。吸附动力学表明,本研究中合成的AFMS对AO7的吸附速率极快。Sips吸附模型对吸附等温线模拟效果最好,从中可知AO7在样品D(由3.0 mL正硅酸乙酯及1.4 mL APTES合成)上的最大吸附量为1.26 mmol·g^-1,远远高于相关文献报道的值。此外,通过吸-脱附循环实验证明,样品D具有良好的稳定性。     

LCAO中轨道对称性匹配的两种判别方法

著名分子轨道理论的核心内容是,组成MO的AO必须满足三条原则即对称性一致原则,最大重叠原则和能量相近原则.在这三条原则中,对称性一致原则是首要的,它决定着AO是否能组合成MO.因此在应用LCAO-MO理论处理问题时,首先要判别相组合的AO对称性是否一致.目前文献[1～5]中,均提出了用对称轴和对称面判别组合轨道的对称性是否一致,但都没有给出完善的判别方法.因此对此问题很有必要进一步研究,以期得到更好的结果.本文在研究LCAO-MO三原则新推证方法[6]的基础上,提出了对称面和对称轴各自独立判据两接近AO的对称性是否一致的理论公式,又通过分析得出了完整的判别方法.该法简便实用,并对常见的s、p、d、f等AO的组合进行了判据,结果无一例外.     

丁腈橡胶/聚氯乙烯/酚醛树脂/受阻酚AO60共混阻尼材料研究

主要研究了丁腈橡胶(NBR)/聚氯乙烯(PVC)/酚醛树脂(PR)/受阻酚AO60共混体系中PR、AO60和增塑剂癸二酸二丁酯(DS)的用量对硫化橡胶力学性能和阻尼性能的影响。在共混体系中添加不超过50phr的AO60,其硫化胶损耗因子-温度曲线仍呈现单峰特征,体系相容性良好。随着AO60含量的增加,硫化胶的玻璃化转变温度提高,阻尼峰值增大。拉伸强度及动态模量先随之增高,然后降低。随着PR含量的增加,硫化胶的拉伸强度随之增加,tanδ峰值温度升高,而阻尼峰值则先提高后降低。加入增塑剂,硫化胶的力学性能、储能模量及玻璃化转变温度都有不同程度的降低。     

吖啶橙-细胞DNA荧光抑制法筛选抗癌药物

在DNA荧光法‘’‘初步筛选抗癌药物的实验中,漠化乙锭（EB）是常用的荧光探针,其本身荧光板弱,但能与双链DNA发生专一性插入作用,使荧光大幅度地增强．但EB不能进入完整的细胞膜［’j．对陕橙（AO）常用于细胞内DNA和RNA的定量测定,并能用于活细胞染色;AO与核酸的结合方式有2种：一种是在嵌入核酸双链的碱基对之间形成AO－DNA复合物,另一种是与单链核酸的磷酸发生静电间相互作用,形成AO－RNA复合物．如用蓝光激发,前者发射峰波长为530urn的绿色荧光,后者发射峰波长为640urn的红色荧卅’‘．本文提出一种对细胞周期非…     

乙二胺改性磁性壳聚糖纳米粒子对酸性染料的吸附特性

利用乙二胺改性磁性壳聚糖纳米粒子(EMCN)吸附酸性橙7 (AO7)和酸性橙10 (AO10). EMCN制备时先通过在由环已烷/正已醇、壳聚糖和铁盐组成的反相微乳体系中加NaOH溶液沉淀剂, 得到磁性壳聚糖纳米粒子, 再经乙二胺改性以增加氨基含量和提高吸附容量. 透射电镜表明, EMCN分散良好, 粒径15-40 nm. 吸附实验表明, AO7和AO10最佳吸附分别在pH 4.0和pH 3.0. EMCN具有粒径小和高表面活性, 因此吸附速率快. 吸附平衡符合Langmuir模型, AO7和AO10的最大吸附容量分别为3.47和2.25 mmol·g^-1. 热力学分析表明吸附过程放热, 且能自发进行. EMCN可用NH⁴OH/NH⁴Cl (pH 10.0)溶液再生并可重复使用.     

On the effect of d orbitals on relativistic bond-length contractions

5d AOs are found to diminish the usual relativistic bond-length contraction in some hydrides. This is shown to be a first-order effect, unrelated to the relativistic expansion of 5d AOs, by both the perturbative Dirac-Fock one-center expansion and Hartree-Fock-Slater methods. The latter method is used to investigate the chemical similarity of Zr and Hf.     

In vitro antioxidative activities of three marine oligosaccharides

The antioxidant activities of three marine oligosaccharides, alginate oligosaccharides (AOs), chitosan oligosaccharides (COs), and fucoidan oligosaccharides (FOs), were investigated in vitro by several antioxidant assays, including hydroxyl radical scavenging, superoxide radical scavenging, erythrocyte hemolysis inhibiting, metal chelating activities, and anti-lipid peroxidation. The results show that these oligosaccharides exhibited different activities in various assays. AOs had the highest scavenging hydroxyl radical activity than FOs and COs at all the tested amounts. COs had the highest scavenging superoxide radical and inhibiting erythrocyte hemolysis activity than AOs and FOs at all the tested amounts. In the assay of chelating Fe2+, COs and FOs indicated good chelation while AOs hardly had any activity. In the assay of anti-lipid peroxidation, only COs had significantly high antioxidant activity.     

The use of comet assay data with a simple reaction mechanism to evaluate the relative effectiveness of free radical scavenging by quercetin, epigallocatechin gallate and N-acetylcysteine in UV-irradiated MRC5 lung fibroblasts

Comet assay data (tail DNA %) have been gathered for the concentration dependent role of three antioxidants (AOs); quercetin (Q), epigallocatechin gallate (EGCG) and N-acetylcysteine (NAC) in reducing UV-induced damage to DNA in normal fetal lung fibroblasts (MRC5). All three compounds demonstrate a concentration dependent reduction maximum with a pro-oxidant effect at higher (though not cytotoxic) concentrations. Manipulation of a simple 4-step reaction mechanism for free radical (FR) scavenging by AOs produced rate constant ratios which allowed the relative effectiveness (Q > EGCG > NAC) of the AOs to be evaluated.     

An improved set of mndo parameters for sulfur

The MNDO parameters for sulfur have been reoptimized. Calculations for a number of sulfur compounds indicate a very significant improvement. Inclusion of d AOs failed to correct the errors for compounds of sulfur in its higher valence states. Since d AOs are not included, the calculations are still confined to compounds of divalent sulfur.     

Electrochemical antioxidant detection technique based on guanine-bonded graphene and magnetic nanoparticles composite materials

An antioxidant (AO) amperometric technique based on guanine attached to graphene and Fe(3)O(4) nanoparticles (NPs) magnetic materials was developed. Guanine molecules acted as an antioxidant competitor were bonded with graphene nanosheets, onto which magnetic Fe(3)O(4) NPs were attached and the as-prepared magnetic composite can be attracted to the electrode surface by an external magnetic field. When applied with negative potentials, the dissolved oxygen was reduced to H(2)O(2) at the electrode surface, and then reacted with the EDTA-Fe(ii) complex via a Fenton-like reaction to produce OH radicals. After oxidation damage by OH radicals, the electrochemical oxidation of guanine gave a decreased current. In the presence of AOs, the reactive oxygen species (ROS, e.g. OH radicals and H(2)O(2)) were scavenged by AOs and fewer guanine probe molecules were oxidized, thus inducing a higher electrochemical oxidation current of guanine. So AOs competed with the guanine probe molecules toward oxidation by ROS. The current signals of the guanine probe molecules were proportional to the concentrations of AOs. A kinetic model was proposed to quantify the ROS scavenging capacities of the AOs. Using guanine as an oxidizable probe and OH radicals and H(2)O(2) as endogenous ROS, this kind of AO detection technique mimicks the antioxidant protection mechanism by small AO molecules in the human body.     

Interrelation of the chemical structure and inhibiting activity of sterically hindered phenols in methyl oleate oxidation in homogeneous and microheterogeneous systems

Specific features of the inhibiting activity of sterically hindered phenolic antioxidants (AOs) 3, 5-Bu^t ₂-4-OHC₆H₂(CH₂)₂C(O)O(CH₂)₂N⁺Me₂R·X⁻ (R = H, Me, C₈H₁₇, C₁₀H₂₁, C₁₂H₂₅, C₁₆H₃₃; X = Br, I), being phenosan derivatives containing the ethanolamine residue substituted at the N atom by an alkyl substituent, were studied. The action of these AOs was studied in the initiated oxidation of homogeneous solutions of methyl oleate in chlorobenzene and an aqueous emulsion medium in the presence of the surfactant sodium dodecyl sulfate. Phenolic AOs act in two directions: they react with peroxy radicals with a rate constant of 0. 98·10⁴ L mol⁻¹ s⁻¹ and decompose hydroperoxides to form molecular products. The effect of hindered phenols as AOs depends substantially on their chemical structure and oxidation conditions. In lipid solutions, they efficiently hinder the oxidation of methyl oleate, outperforming the action of α-tocopherol, dibunol, phenosan K, and its methyl ester taken in comparative concentrations. The inhibiting activity of the AOs decreases substantially with the chain elongation of the R substituent. For oxidation in an aqueous emulsion medium, the inhibition effect of the AOs under study weakens compared to oxidation in a homogeneous solution, which is accompanied by the disappearance of differences in efficiency of different AOs.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 323–328, February, 2005.     

分子轨道成键性质及原子间化学键强度的成键能判据

本文定义了成键能Eb并用作分子轨道成键性质和分子中原子间化学键强度的判据。与Mulliken重叠布居Pb不同, 在成键能Eb中同时包含了原子轨道间的重叠因素和原子轨道的能量因素。对一些分子所作计算结果表明, 成键能判据较Mulliken重叠布居判据所得结论与实验更相符。     

Force in scf theories

A new force approach is reported in which we improve the wavefunction so that the Hellmann-Feynman theorem is satisfied. A sufficient condition for the Hellmann-Feynman theorem to be satisfied is that the basis set includes AO derivatives ?x_r/?x_rfor any basis x_r. Here we test a procedure in which only the first derivative AOs are added to the “parent” AOs. The results are very encouraging.     

MPI/OpenMP hybrid parallel algorithm for resolution of identity second‐order Møller–Plesset perturbation calculation of analytical energy gradient for massively parallel multicore supercomputers

A massively parallel algorithm of the analytical energy gradient calculations based the resolution of identity Møller–Plesset perturbation (RI‐MP2) method from the restricted Hartree–Fock reference is presented for geometry optimization calculations and one‐electron property calculations of large molecules. This algorithm is designed for massively parallel computation on multicore supercomputers applying the Message Passing Interface (MPI) and Open Multi‐Processing (OpenMP) hybrid parallel programming model. In this algorithm, the two‐dimensional hierarchical MP2 parallelization scheme is applied using a huge number of MPI processes (more than 1000 MPI processes) for acceleration of the computationally demanding O (N ⁵) step such as calculations of occupied–occupied and virtual–virtual blocks of MP2 one‐particle density matrix and MP2 two‐particle density matrices. The new parallel algorithm performance is assessed using test calculations of several large molecules such as buckycatcher C₆₀@C₆₀H₂₈ (144 atoms, 1820 atomic orbitals (AOs) for def2‐SVP basis set, and 3888 AOs for def2‐TZVP), nanographene dimer (C₉₆H₂₄)₂ (240 atoms, 2928 AOs for def2‐SVP, and 6432 AOs for cc‐pVTZ), and trp‐cage protein 1L2Y (304 atoms and 2906 AOs for def2‐SVP) using up to 32,768 nodes and 262,144 central processing unit (CPU) cores of the K computer. The results of geometry optimization calculations of trp‐cage protein 1L2Y at the RI‐MP2/def2‐SVP level using the 3072 nodes and 24,576 cores of the K computer are presented and discussed to assess the efficiency of the proposed algorithm. © 2017 Wiley Periodicals, Inc.