Identification and releasing characteristics of β-cyclodextrin–phenylethanoid glycosides inclusion complex

β-Cyclodextrin–phenylethanoid glycosides inclusion complex was prepared and its releasing characteristic was investigated in this study. The results, obtained from Fourier-transform infrared spectroscopy, thermogravimetric analysis, and X-ray diffraction, indicated that phenylethanoid glycosides (PG) were able to form an inclusion complex with β-cyclodextrin (β-CD). This complex exhibited different spectroscopic features, thermal stability and crystalline structure from PG. Molecular simulation results showed the benzene rings of PG incorporating into the hydrophobic cavity of β-CD during the complex formation. Furthermore, the releasing rate of the included PG in the inclusion complex was positively correlated with temperature and it was slightly higher in 0.5 % HCl solution than in water. These results suggested that the complexation technique using β-CD was a promising strategy for increasing the applications of PG in food and healthcare industries.     

Electro-oxidation of amino-functionalized multiwalled carbon nanotubes

We report the electrochemistry of amino-functionalized multiwalled carbon nanotubes (MWCNTs-NH₂) in the pH range from 0.3 to 6.4 using quantitative cyclic voltammetry (CV) and single entity electrochemistry measurements, making comparison with non-functionalized MWCNTs. CV showed the latter to both catalyze the solvent (water) decomposition and to undergo irreversible electro-oxidation forming oxygen containing surface functionality. The MWCNTs-NH₂ additionally undergo an irreversible oxidation to an extent which is dependent on the pH of the solution, reflecting the variable amount of deprotonated amino groups present as a function of pH. Nano-impact experiments conducted at the single particle level confirmed the oxidation of both types of MWCNTs, showing agreement with the CV. The pK_a of the amino groups in MWCNTs was determined via both electrochemical methods giving consistent values of ca. 2.5.

A new and generic approach to the study of the oxidation of different forms of CNTs is found by using quantitative single entity and ensemble electrochemistry measurements.     

Co_2Fe(μ_3-S)(CO)_7(CH_3CSNH)的合成与结构

用Co2（CO）8与CH3CSNH2反应制得产物Ⅰ，又用Na2Fe（CO）4与Ⅰ反应制得产物Ⅱ（Ⅰ：Co3（μ3－S）（CO）7（CH3CSNH），Ⅱ：Co2Fe（μ3-S）（CO）7（CH3CSNH）．通过元素分析。IR、UV、1HNMR、MS表征并用X射线衍射法测得Ⅱ的单晶结构.该簇合物属三斜晶系、PT空间群，晶胞参数：a=0．9203（1），b=1．1296（2），c=1.1425（2）nm；α=116．40°（2），β＝101．92°（2），γ＝92．58°（1）；z＝2，V=1．2162nm3，Dc＝1．698cm3，μ＝21．89cm-1.结构分析表明，Co2FeS构三角锥分子骨架，所有CO均为端基配体，S1为面桥基配体，CH3CSNH为双齿配体，与Co、Fe形成五元环结构．     

A first-principles investigation on interactions between various surface-terminated diamond films

To elucidate the influence of different terminations on diamond surface interaction, the geometry and electronic structures of the diamond films modified by different terminations (H, F, O, NH₂, and OH) are studied by using the first principles method. Strong bonding is formed between the clean diamond surfaces, which suggest an obvious interface interaction. Both H and F terminals have significant effects on the reduction of the interface interactions. Due to the larger difference in electronegativity between C and F, the F termination layer has a higher electron density coverage to give a larger repulsive force. Therefore, the interaction between the F-terminated diamond interfaces is stronger than that between the H-terminated diamond interfaces. The O-terminated diamond surfaces are unstable. The NH₂- and OH-terminals have weak interaction due to the presence of large functional group atoms that leads to an electronic offset.     

Cuprous oxide/titanium dioxide composite photocatalytic decolorization of reactive brilliant red X-3B dyes wastewater under visible light

Research on Chemical Intermediates - In recent years, how to improve photocatalytic performance under visible light has become one of the research hot topics. The nano-TiO2 particles were...     

Electrochemically Determining Electronic Structure of ZnO Quantum Dots with Different Surface Ligands

The electronic structure of quantum dots (QDs) including band edges and possible trap states is an important physical property for optoelectronic applications. The reliable determination of the energy levels of QDs remains a big challenge. Herein we employ cyclic voltammetry (CV) to determine the energy levels of three types of ZnO QDs with different surface ligands. Coupled with spectroscopic techniques, it is found that the onset potential of the first reductive wave is likely related to the conduction band edges while the first oxidative wave originates from the trap states. The determined specific energy levels in CV further demonstrates that the ZnO QDs without surface ligands mainly have oxygen interstitial defects whilst the ZnO QDs covered with ligands contain oxygen vacancies. The present electrochemical method offers a powerful and effective way to determine the energy levels of wide bandgap ZnO QDs, which will boost their device performance.     

Formation and Characterization of Zr<Superscript>4+</Superscript> Stabilized by Neutral Tridentate Ligands in the Gas Phase

Ligated tetrapositive metal ions are rare gas-phase species which tend to form complexes with lower charges due to the high 4th ionization energies of metals. We report the observation of tetrapositive Zr(TMPDA)₃⁴⁺ and Zr(TMOGA)₃⁴⁺ complexes in the gas phase by electrospray ionization of Zr(ClO₄)₄/TMPDA and Zr(ClO₄)₄/TMOGA mixtures. The Zr⁴⁺ center in both complexes is coordinated by nine atoms from three neutral diamide ligands forming nine-coordinate twisted tricapped trigonal prismatic geometry on the basis of DFT calculations. Collision-induced dissociation of both complexes resulted in the loss of protonated ligands to form tripositive Zr(TMPDA)(TMPDA-H)³⁺ and Zr(TMOGA)(TMOGA-H)³⁺ products which retain the IV oxidation state of zirconium at the cost of charge reduction from 4+ to 3+ of the whole complexes. The very high 4th ionization energy of zirconium (34.34 eV) makes tetrapositive zirconium complex the most challenging tetracation to be stabilized against charge reduction in the gas phase to date.

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一类新型多方向准零刚度隔振平台

本文提出了一种新的多自由度非线性隔振平台．利用一组预压的三角机构和曲面边界同时实现了竖直-旋转多自由度上的负刚度特性,结合正刚度原件,实现竖直-旋转多自由度准零刚度特性．首先,文章基于平面问题建立竖直-旋转两自由度隔振平台的力学模型,确定结构参数与非线性刚度之间的关系．可以看到,通过设计预压弹性元件的结构参数可以同时实现两自由度的准零刚度特性．然后,利用谐波平衡法建立振动响应与频率之间的关系,确定有效的振动带隙的宽度,由此确定结构参数的最优取值．本文提出的隔振平台可以用于大型装备的隔振,也适用于微振动的工况,还可以作为教学的演示实验．     

Single Nanoparticle Voltammetry: Contact Modulation of the Mediated Current

The cyclic voltammetric responses of individual palladium‐coated carbon nanotubes are reported. Upon impact—from the solution phase—with the electrified interface, the nanoparticles act as individual nanoelectrodes catalyzing the hydrogen‐oxidation reaction. At high overpotentials the current is shown to reach a quasi‐steady‐state diffusion limit, allowing determination of the tube length. The electrochemical response of the individual nanotubes also reveals the system to be modulated by the electrical contact between the electrode and carbon nanotube. This modulation presents itself as fluctuations in the recorded Faradaic current.     

A simplified methodology: pH sensing using an in situ fabricated Ir electrode under neutral conditions

Herein, a simplified fabrication method for the producing of a pH-sensitive iridium electrode is developed. The in situ electrochemical fabrication of an iridium oxide film is optimized and shown to be achievable under neutral conditions rather than the acidic conditions hitherto employed. The formation of a pH sensitive Ir(III/IV) hydrous film is confirmed via XPS. The amperometric pH-sensing properties of this electrochemically generated material were investigated using square wave voltammetry. In the pH range 2–13, the iridium oxide redox signal has a pH dependency of 86.1 ± 1.1 mV per pH unit for midpoint potentials with uncertainties being ± 0.01–0.05 pH. Finally, the newly developed pH sensor was used to measure the pH of a natural water sample with excellent results as compared to a conventional glass pH probe.