晶体结构模型软件Diamond的使用技巧

通过用Diamond软件构造C60笼型分子结构模型以及对笼型分子各个面的分别封闭,介绍了从“.CIF”格式文件中获得晶体结构数据;原子间距的测量;插入“dummy”原子辅助构造多面体及利用插入“dummy”原子对五边形、六边形分别进行封闭等Diamond软件的使用方法和技巧。     

The Electro‐Oxidation of Formaldehyde at a Boron‐Doped Diamond Electrode

Abstract

The characteristics of the boron‐doped diamond (BDD) electrode in this work were studied by atomic force microscope (AFM), scanning electron microscopy, and Raman spectroscopy. The electro‐oxidation of formaldehyde at the BDD electrode in 0.5 M K₂SO₄ with different pH was studied by cyclic voltammetry and amperometry. There is no significant oxidation peak of formaldehyde in acidic solution because the oxidation of formaldehyde is at the potential range of water discharge. However, in neutral solution, there is a well‐defined oxidation peak at about +2.2 V vs. Ag/AgCl. The relation between the response current and formaldehyde concentration is linear behavior at the concentration range from 50 to 600 µM. Besides, in neutral solution, the oxidation of formaldehyde is dominated by indirect oxidation at lower formaldehyde concentration, and it is dominated by direct oxidation at higher concentration. Finally, in alkaline solution, the oxidation of formaldehyde is dominated by indirect oxidation caused by a powerful oxidant and is related to the ratio of the amounts of formaldehyde and OH molecules at the BDD electrode surface.     

Diamond nanospherulite: A novel material produced at carbon-water interface by pulsed-laser ablation

Formation of carbon nanoparticles with perfectly spherical.shape and diamond structure (diamond nanospherulite) by laser-ablating a variety of carbon samples in water is reported for the first time The studies reveal that molten carbon nanoparticles generated by laser ablation are quenched directly by water and end up as diamond nanospherulites,possibly due to the high pressure arising from surface tension and the high stability resulting from termination of dangling bonds with hydrogen atoms.     

Study of the “Diamond—Pyrolytic Carbon” nanocomposites using lithium intercalation

Electrochemical behavior of the diamond-based composites: a nanodiamond—pyrocarbon composite and Carbal, as well as vacuum-high-temperature-annealed polycrystalline diamond is studied by the cathodic lithium incorporation from LiPF ₆ solution in a (1 : 4) propylene carbonate—diethyl carbonate mixture. The amount of incorporated lithium steadily increases with the nondiamond (graphite-like) carbon content in the composite. The intercalation capacity of Carbal equals ~33 mA-h per g of the graphite-like carbon. It is concluded that the graphite-like carbon distributed in the nano-(or micro-)diamond carcass is the electrochemically active phase in the composites.Translated from Elektrokhimiya, Vol. 40, No. 12, 2004, pp. 1508–1513.Original Russian Text Copyright © 2004 by Pleskov, Kulova, Skundin, Krotova, Ralchenko, Korchagina, Gordeev.     

High Resistive ZnO／Diamond／Si Films Grown via Metal-organic Chemical Vapour Deposition

Piezoelectric ZnO layers with high resistivity for surface acoustic wave applications were prepared on polycrystalline diamond/Si substrates with(Ill) orientation via metal-organic chemical vapour deposition.The characteristics of the films were optimized through different growth methods. The comparative study of the X-ray diffraction spectra and scanning electron microscopic images showed that the final-prepared ZnO films were dominantly c-axis oriented. Zn and O elements in the final prepared ZnO films were investigated through X-ray photoelectron spectroscopy. According to the statistical results, the n(Zn)/n(O) ratio is near 1. The Raman scattering was also performed in back scattering configuration. E2 mode was observed for the final films, which indicated that the better quality ZnO films had been obtained. The resistivity of the films was also enhanced via the modification of the growth methods.     

Simultaneous Determination of Creatine and Creatinine using Monocrystalline Diamond Paste–Based Amperometric Biosensors

Abstract

In order to determine creatine and creatinine, amperometric diamond paste biosensors were proposed. A bienzymatic biosensor based on creatinase and sarcosine oxidase was used for the assay of creatine and a trienzymatic biosensor based on creatinase, sarcosine oxidase, and creatininase was proposed for the assay of creatinine. The linear concentration ranges are of fmol/L magnitude order, with very low limits of detection. The biosensors proved to be highly reliable for determination of creatine and creatinine as raw materials in pharmaceutical formulations as well as in serum samples.     

Direct and Simultaneous Determination of Phenol, Hydroquinone and Nitrophenol at Boron-Doped Diamond Film Electrode

The electrochemical characteristics of multi-component phenolic pollutants, such as phenol （Ph）, hydroquinone （HQ） and 4-nitrophenol （4-NP）, were investigated on boron-doped diamond （BDD） film electrode by differential pulse voltammetry （DPV） technique. A simple and feasible platform was accordingly established for the direct and simultaneous determination of these three phenolic pollutants. Results showed that, Ph, HQ and 4-NP gave obvious oxidation peaks on BDD electrode at the potential of 1.24, 0.76 and 1.52 V, respectively. Each of them displayed good linear relationship between their oxidation peak currents and their corresponding concentrations in a rather wide range coexisting with one or two of the other phenolic pollutants. The detection limits of Ph, HQ and 4-NP were estimated to be as low as 1.82×10^-6, 1.67×10^-6 and 1.44×10^-6 mol·L^-1, respectively. Therefore, a promising direct and simultaneous electrochemical determination method of multi-component phenolic pollutants in wastewater samples was constructed successfully on BDD electrode with advantages being rapid, simple, convenient, sensitive, in situ and inexpensive.     

Diamond软件在晶体对称性教学中的应用-32点群晶体模型库的建立

介绍了用Diamond软件构造32点群晶体结构模型的方法,给出了建立晶体结构模型的具体参数.利用此模型有助于加深学生对点群及其与晶体结构关系的理解.     

Electrocatalytic Oxidation of Organic Pollutants on Boron-Doped Diamond and Ti–Ru Oxide Anodes in Sulfate Medium

Electrochemical oxidation for degradation of industrial dye Methyl Orange in aqueous sulfate solutions with various electrocatalytic materials: boron-doped diamond electrode and electrode based on titanium and ruthenium oxides. The influence exerted by the main working parameters of electrolysis (current density, concentration of Methyl Orange, pH) on the discoloration efficiency and on the chemical oxygen demand (COD) was examined. It was shown that an increase in the current density and a decrease in the pollutant concentration improve the process efficiency. However, this leads to an increase in the specific electric energy consumption per unit mass of COD. It was found that the boron-doped diamond electrode is a more efficient electrocatalytic material, compared with electrode based on titanium and ruthenium oxides. At low concentrations of Methyl Orange (<50 mg L^–1), there exists the possibility in principle of using the electrode based on titanium and ruthenium oxides not only for discoloration, but also for making lower the COD level.     

Square‐Wave Voltammetry Determination of Aspartame in Dietary Products Using a Boron‐Doped Diamond Electrode

Abstract

The use of square‐wave voltammetry in conjunction with a cathodically pretreated boron‐doped diamond electrode for the analytical determination of aspartame in dietary products is described. In this determination, the samples were analyzed without previous treatment in a 0.5 mol l^?1 H₂SO₄ solution. A single oxidation peak at a potential of 1.6 V vs. Ag/AgCl (3.0 mol l^?1 KCl) with the characteristics of an irreversible reaction was obtained. The analytical curve was linear in the aspartame concentration range 9.9×10^?6 to 5.2×10^?5 mol l^?1 with a detection limit of 2.3×10^?7 mol l^?1. The relative standard deviation (n=5) obtained was smaller than 0.2% for the 1.0×10^?4 mol l^?1 aspartame solution. The proposed method was applied with success to the determination of aspartame in several dietary products and the results were similar to those obtained using an HPLC method at 95% confidence level.     

Differential Pulse Voltammetric Determination of Sildenafil Citrate (Viagra®) in Pharmaceutical Formulations Using a Boron-Doped Diamond Electrode

The determination of sildenafil citrate using differential pulse voltammetry and a cathodically pre-treated boron-doped diamond electrode is described. The obtained analytical curve is linear in the sildenafil concentration range 7.3 × 10^?7 ? 7.3 × 10^?6 mol L^?1 in a 0.1 mol L^?1 H₂SO₄, with a detection limit of 6.4 × 10^?7 mol L^?1. The proposed method, which is fast and simple to carry out, was successfully applied in the determination of sildenafil citrate in Viagra® pharmaceutical formulations, with results in close agreement (at 95% confidence level) with those obtained using a comparative HPLC method.     

Diamond软件及数据库在晶体结构教学中的应用——以钙钛矿(CaTiO3)为例

晶体结构是《材料科学基础》课程的重中之重,是学好后续专业知识的基础,此部分内容概念抽象,需要很强的空间想象能力,传统的二维图片很难表达离子/原子的三维空间排布。本文以钙钛矿(CaTiO₃)结构教学为例,借助Diamond软件和网络数据库构建立体性和可操作性三维晶体结构模型,利用此模型可以清晰直观的看到晶体结构内部原子的排列。通过改变立方体位置和配位体中心原子构建不同的晶体结构模型,采用坐标系法、最紧密堆积法和多面体的连接方式三种方法,对钙钛矿的晶体结构进行全面的描述,有助于提高学生的学习兴趣和效率。     

The Use of Boron‐Doped Diamond Electrodes for the Amperometric Determination of Flavonoids in a Flow Injection System

Abstract

This paper describes the use of boron‐doped diamond electrode for the amperometric detection and quantification of flavonoids in tea samples using a flow injection system. Flavonoids are phenol derivates widely distributed in fruits, nuts, seeds, flowers, vegetable peels, and beverages; they are known to exhibit high antioxidative activities. After optimization, the experiments were performed at a fixed potential of 0.42 V vs Ag/AgCl with a flow rate of 2.5 ml min^?1 in a Britton‐Robinson buffer at pH 5.0. The results revealed that the peak current increases linearly with rutin concentration in the interval 0.1–2.5×10^?4 mol L^?1 and the detection limit was 7.7×10^?6 mol L^?1. The method was used for the determination of rutin in three different green tea (Camellia sinensis) infusions by the direct addition of 150 µL of untreated sample. The repeatability of current responses for injections of 150 µL rutin was evaluated to be 2.1% (n=20) and the analytical frequency was 100 Hz h^?1. The results were compared with the results obtained by high‐performance liquid chromatrography‐diode ray detector.     

用Diamond TG/DTA热重/差热综合热分析仪在外加磁场下研究磁性材料相转变

介绍综合热分析仪Diamond TG/DTA在磁性材料研究中的应用.提出在外加磁场作用下,得到样品的热重曲线(TG),由TG曲线分析样品磁性相变及样品居里温度变化的原因,看到稀土铁基金属间化合物样品替代的Co元素的站位和元素之间相互作用对居里温度有很大影响.作为一种测量居里温度的方法,拓展Diamond TG/DTA热分析仪应用研究领域.     

Diamond nanoparticles as a way to improve electron transfer in sol–gel l-lactate biosensing platforms

In the present work, we have included for the first time diamond nanoparticles (DNPs) in a sol–gel matrix derived from (3-mercaptopropyl)-trimethoxysilane (MPTS) in order to improve electron transfer in a lactate oxidase (LOx) based electrochemical biosensing platform. Firstly, an exhaustive AFM study, including topographical, surface potential (KFM) and capacitance gradient (CG) measurements, of each step involved in the biosensing platform development was performed. The platform is based on gold electrodes (Au) modified with the sol–gel matrix (Au/MPTS) in which diamond nanoparticles (Au/MPTS/DNPs) and lactate oxidase (Au/MPTS/DNPs/LOx) have been included. For the sake of comparison, we have also characterized a gold electrode directly modified with DNPs (Au/DNPs). Secondly, the electrochemical behavior of a redox mediator (hydroxymethyl-ferrocene, HMF) was evaluated at the platforms mentioned above. The response of Au/MPTS/DNPs/LOx towards lactate was obtained. A linear concentration range from 0.053 mM to 1.6 mM, a sensitivity of 2.6 μA mM⁻¹ and a detection limit of 16 μM were obtained. These analytical properties are comparable to other biosensors, presenting also as advantages that DNPs are inexpensive, environment-friendly and easy-handled nanomaterials. Finally, the developed biosensor was applied for lactate determination in wine samples.     

Spectroscopic Properties of a Biologically Relevant [Fe2(μ-O)2] Diamond Core Motif with a Short Iron-Iron Distance

Diiron cofactors in enzymes perform diverse challenging transformations. The structures of high valent intermediates ( Q in methane monooxygenase and X in ribonucleotide reductase) are debated since Fe−Fe distances of 2.5–3.4 Å were attributed to “open” or “closed” cores with bridging or terminal oxido groups. We report the crystallographic and spectroscopic characterization of a Fe^III₂(μ-O)₂ complex ( 2 ) with tetrahedral (4C) centres and short Fe−Fe distance (2.52 Å), persisting in organic solutions. 2 shows a large Fe K-pre-edge intensity, which is caused by the pronounced asymmetry at the T_D Fe^III centres due to the short Fe−μ−O bonds. A ≈2.5 Å Fe−Fe distance is unlikely for six-coordinate sites in Q or X , but for a Fe₂(μ-O)₂ core containing four-coordinate (or by possible extension five-coordinate) iron centres there may be enough flexibility to accommodate a particularly short Fe−Fe separation with intense pre-edge transition. This finding may broaden the scope of models considered for the structure of high-valent diiron intermediates formed upon O₂ activation in biology.     

钻石对顶砧(Diamond Anvil Cell,DAC)高压产生技术及在高压条件下的光物理和光化学研究

高压作为一个重要的物理参量引入到科学研究的各个领域将会大大扩展研究的范围.本文介绍了一种简单安全的产生高压的技术和在高压条件下进行的一些光物理和光化学研究工作,并指出了今后在高压光物理和光化学研究领域的若干重要研究方向.     

Aggregation Stability of SiO2, FeOOH, ZrO2, CeO2, and Natural Diamond Sols and Their Binary Mixtures: 2. The Photometric Study of Heterocoagulation of SiO2–FeOOH, SiO2–ZrO2, SiO2–CeO2, and CeO2–Natural Diamond Binary Systems in KCl Solutions

The aggregation stability of 1 : 1 and 3 : 1 (by volume) binary mixtures of two hydrophobic (SiO₂–FeOOH), one hydrophobic and one hydrophilic (SiO₂–ZrO₂, SiO₂–CeO₂), and two hydrophilic (CeO₂–natural diamond) sols was studied by photometry over a wide range of KCl concentrations at pH 6 and 3. The stability of the mixed binary sols was determined by the stability of the sol with a predominant particle number concentration. In the SiO₂–FeOOH system, the phenomenon of heteroadagulation stabilization was caused by the electrostatic factor of the stability of adsorbed SiO₂ particles and, in the SiO₂–ZrO₂ system, by the structural factor of the stability of adsorbed hydrophilic ZrO₂ particles. The stability of binary mixtures containing one or two hydrophobic components is qualitatively explained in terms of the Derjaguin theory of heterocoagulation of hydrophobic colloids. The stability of the binary system of two hydrophilic components (CeO₂–natural diamond) is determined by the structural component of the interaction energy of particles.