Regio- and Enantioselective Epoxy Ring Opening of 2,3-Epoxy-3-phenyl Alcohols/Carboxylic Acids and Their Derivatives

Russian Journal of Organic Chemistry - The review highlights the progress of ring opening of 2,3-epoxy-3-phenyl alcohols/carboxylic acids and their derivatives over the past few decades. The...     

Preparation and electrochemical properties of Li<Subscript>4</Subscript>Ti<Subscript>5</Subscript>O<Subscript>12</Subscript>/Ti<Subscript>4</Subscript>O<Subscript>7</Subscript> composite for lithium-ion batteries

In order to improve the rate capability of Li₄Ti₅O₁₂, Ti₄O₇ powder was successfully fabricated by improved hydrogen reduction method, then a dual-phase composite Li₄Ti₅O₁₂/Ti₄O₇ has been synthesized as anode material for lithium-ion batteries. It is found that the Li₄Ti₅O₁₂/Ti₄O₇ composite shows higher reversible capacity and better rate capability compared to Li₄Ti₅O₁₂. According to the charge-discharge tests, the Li₄Ti₅O₁₂/Ti₄O₇ composite exhibits excellent rate capability of 172.3 mAh g^?1 at 0.2 C, which is close to the theoretical value of the spinel Li₄Ti₅O₁₂. More impressively, the reversible capacity of Li₄Ti₅O₁₂/Ti₄O₇ composite is 103.1 mAh g^?1 at the current density of 20 C after 100th cycles, and it maintains 84.8% of the initial discharge capacity, whereas that of the bare spinel Li₄Ti₅O₁₂ is only 22.3 mAh g^?1 with a capacity retention of 31.1%. The results indicate that Li₄Ti₅O₁₂/Ti₄O₇ composite could be a promising anode material with relative high capacity and good rate capability for lithium-ion batteries.     

Radiolabeling of DNA nanostructure with 99mTc using DTPA as a chelate

In the field of nanotechnology, DNA-based nanoscale materials have facilitated the construction of DNA polyhedrons with different shapes and sizes by using predictable base pairing and highly tunable conformation. In this study DNA bipyramid nanostructures with one arm chain (T20-DBNs) were successfully prepared in a single annealing procedure. ^99mTc-A20 ssDNA was obtained by radiolabeled DTPA-A20 with ^99mTc, and then ^99mTc-DTPA-DBNs were obtained by hybridizing T20-DBNs with ^99mTc-A20 ssDNA. We focused on studying a method of ^99mTc radiolabeling DNA nanostructures with DTPA as a chelate, and hoped to develop a new SPECT molecular imaging probe based on DNA nanostructures.

     

DRIFTS investigation and DFT calculation of the adsorption of CO on Pt/TiO2, Pt/CeO2 and FeOx/Pt/CeO2

Molecular structures and vibrational spectra of the CO species adsorbed on the Pt/TiO2, Pt/CeO2 and FeOx/Pt/CeO2 have been investigated by means of density functional theory (DFT) calculation and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). The geometrical structures and vibrational frequencies were obtained at the MPW1PW91/SDD level. Theoretical calculation shows that the calculated IR spectra were in good agreement with the experimental results. The calculated results clarify the assignment of the adsorbed CO species on the surface of Pt/TiO2, Pt/CeO2 and FeOx/Pt/CeO2.     

高校“微课”教学设计促进教学效果策略研究

开放教学资源下新的教学方式"微课"的出现引起了国内外知名学者的广泛关注,越来越多的研究者将微课的研究视角从理论分析转移到了实践探索.该研究从剖析高等学校微课教学设计入手,分析了目前高校微课设计的误区和存在的问题,以笔者参加首届全国高校数学微课程教学设计竞赛为背景,从理论和实践两个层面提出了有效微课教学设计环节和实施策略,以期对高校微课教学模式的构建研究起到一定的借鉴意义.     

The development of carbon capture by functionalized ionic liquids

The CO₂ capture by functionalized ionic liquids developed in recent years was critically reviewed, where the relationship between the capacity and the enthalpy as well as that between the structure and the viscosity were discussed. This work reviews with special emphasis on tuning the basicity and designing the structure for improving absorption properties, such as adjusting the capacity and energy consumption, and decreasing the viscosity of ionic liquid. Subsequently, some unconventional absorption phenomenon was also set out detailed. Finally, the recent efforts in understanding CO₂ absorption and the future research directions were outlined.     

Heterometallic iodoplumbates modified by copper(I) or silver(I) with viologens

Cu/Ag(I) were introduced into iodoplumbate systems to produce two new heterometallic iodoplumbates with viologen as templates, i.e. (PV)₂(Pb₂Cu₂I₁₀) (1) and [(BV)(Pb₂AgI₇)]_n (2) (PV²⁺ = propyl viologen, BV²⁺ = benzyl viologen), in which the common connection of PbI₆ units have been remarkably altered. In (PV)₂(Pb₂Cu₂I₁₀) (1), two PbI₆ octahedra are bridged by two CuI₄ tetrahedra via face-sharing to give a (Pb₂Cu₂I₁₀)^4? cluster, but the ternary one-dimensional polymeric (Pb₂AgI₇)_n^2n? of [(BV)(Pb₂AgI₇)]_n (2) is assembled from edge-sharing AgI₄ tetrahedra and PbI₆ octahedra. Their optical band gaps and fluorescence were also discussed. The absorption edges of haloplumbates could be engineered by introduction of suitable conjugated molecules as templates.     

Synthesis of ionic liquids functionalized β-cyclodextrin-bonded chiral stationary phases and their applications in high-performance liquid chromatography

Four novel ILs functionalized β-cyclodextrins (β-CDs) were prepared by treating 6-tosyl-β-cyclodextrin with 1,2-dimethylimidazole or 1-amino-1,2,3-triazole, and bonded to silica gel to obtain chiral stationary phases (CSPs) to be used in high-performance liquid chromatography (HPLC). The separation performances of these CSPs were examined with 16 chiral aromatic alcohol derivatives and 2 racemic drugs in acetonitrile-based polar-organic mobile phase. Excellent enantioseparations were achieved for most of the analytes. The highest value of resolution factor calculated is 6.868. Comparison of the performance of 8a, 8b, 8c and 8d suggests that the positively charged imidazole group provides electrostatic interactions probably through strong H-bonding with the analytes, whereas the cationic triazole, which forms a weaker ion pair with its counter ion, is more capable of participating in ion-pairing interactions with acidic analytes. However, for compounds 12 and 13, which have larger molecular volumes than the other analytes, the interactions between analytes and both cationic imidazole and its counter ion of the selectors play an important role in the chiral resolution. Moreover, the high resolutions were found to depend on the properties of the cations and anions on the selectors in combination with the chiral recognition sites on the rim of the CD. The ionic strength in mobile phase affects the relative interactions between analytes and the chiral selector as well as between analytes and solvents.     

Synthesis and luminescent properties of SnO2:Eu nanopowder via polyacrylamide gel method

Nanocrystalline europium-doped tine oxide (SnO₂:Eu) were synthesized by a polyacrylamide gel method. The effects of heat treatment on structure, grain size and luminescence properties of SnO₂:Eu were studied with X-ray powder diffraction, transmission electron microscopy and photoluminescence measurements. The results indicate that high heat treatments can enhance greatly luminescence intensity of the samples. Furthermore, the presence of carbon network/cages in the polyacrylamide gel can effectively prevent particles agglomeration, so even when sintered at higher temperatures (1000 °C), the grain size is still below 20 nm.     

Platinum nanoparticles supported MoS2 nanosheet for simultaneous detection of dopamine and uric acid

Herein, platinum nanoparticles-decorated molybdenum disulfide(Pt NPs@MoS_2) nanocomposite has been synthesized via a microwave-assisted hydrothermal method, which was characterized by transmission electron microscopy(TEM) and powder X-ray diffraction(XRD). This MoS_2-based nanocomposite modified glass carbon electrode(Pt NPs@MoS_2/GCE) exhibited excellent electrocatalytic activity toward dopamine(DA) and uric acid(UA) due to their synergistic effect. Two well-defined oxidation peaks of DA and UA were obtained at Pt NPs@MoS_2/GCE with a large peak separation of 160 m V(DA-UA), suggesting that the modified electrode could individually or simultaneously analyze DA and AA. Under the optimal conditions, the peak currents of DA and UA were linearly dependent on their concentrations in the range of 0.5–150 and 5–1000 mmol/L with detection limit of 0.17 and 0.98 mmol/L, respectively. The proposed MoS_2-based sensor can also be employed to examine DA and UA in real samples with satisfactory results. Therefore, the Pt NPs@MoS_2 nanocomposite might offer a good possibility for electrochemical sensing and other electrocatalytic applications.