A metal-organic framework containing discrete single-walled nanotubes based on curved trinuclear [Cu3(micro3-O)(micro-OH)(triazolate)2]+ building blocks

A metal-organic nanotubular architecture was built from parallel-aligned single-walled nanotubes which interlink by means of mu(3)-bridged counterions, representing the first example of coordination nanotubes presumably generated from two-dimensional (2D) sheets.     

Efficient Intersystem Crossing and Long-lived Charge-Separated State Induced by Through-Space Intramolecular Charge Transfer in a Parallel Geometry Carbazole-Bodipy Dyad

The design of efficient heavy atom-free triplet photosensitizers (PSs) based on through bond charge transfer (TBCT) features is a formidable challenge due to the criteria of orthogonal donor-acceptor geometry. Herein, we propose using parallel (face-to-face) conformation carbazole-bodipy donor-acceptor dyads (BCZ-1 and BCZ-2) featuring through space intramolecular charge transfer (TSCT) process as efficient triplet PS. Efficient intersystem crossing (Φ_Δ=61 %) and long-lived triplet excited state (τ_T=186 μs) were observed in the TSCT dyad BCZ-1 compared to BCZ-3 (Φ_Δ=0.4 %), the dyad involving TBCT, demonstrating the superiority of the TSCT approach over conventional donor-acceptor system. Moreover, the transient absorption study revealed that TSCT dyads have a faster charge separation and slower intersystem crossing process induced by charge recombination compared to TBCT dyad. A long-lived charge-separated state (CSS) was observed in the BCZ-1 (τ_CSS=24 ns). For the first time, the TSCT dyad was explored for the triplet-triplet annihilation upconversion, and a high upconversion quantum yield of 11 % was observed. Our results demonstrate a new avenue for designing efficient PSs and open up exciting opportunities for future research in this field.     

Mixed-valence Cu(II)Cu(I)15I17 cluster builds up a 3D metal-organic framework with paramagnetic and thermochromic characteristics

Four cubane-like Cu4I4 units are assembled around an iodine atom to form the giant, mixed-valent Cu(II)Cu(I)15I17 cluster. The Cu(II)Cu(I)15I17 cluster and a bipyrazole linker form a 3D open framework with paramagnetic and thermochromic properties. This paper also touches on the resemblance of this cluster to the self-similar object of a Sierpinski tetrahedron.     

甲基丙烯酸甲酯的可控/“活性”细乳液光聚合

在室温下, 以2,2,6,6-四甲基-4-羟基哌啶-1-氧自由基(HTEMPO)为调控介质, 1-羟基-环己基-苯基甲酮(Irgacure 184)为引发剂, 采用光化学方法研究了甲基丙烯酸甲酯(MMA)/十二烷基硫酸钠(SDS)/十六醇(CA)/水细乳液体系的光聚合反应控制动力学. 结果表明, 该细乳液体系非常稳定, 在整个聚合过程中即没有絮凝物产生, 也没有沉淀析出, 获得了良好的ln([M0]/[M])与时间、数均分子量与转化率之间的线性动力学关系, 并且在整个聚合反应过程中MMA均聚物的分子量分布比较窄, 其多分散性指数较低(PDI=1.27~1.36), 具有明显的活性聚合特征.     

A rare chiral self-catenated network formed by two cationic and one anionic frameworks

A chiral heterometallic complex, obtained from the solvothermal reaction of [Zn(4-pytpy)2](BF4)2 [4-pytpy=4'-(4-pyridyl)-2,2':6',2'-terpyridine] and CuCN, exhibits a rare self-catenated network formed by two 3D cationic and one 3D anionic frameworks.     

平稳随机过程的小波分析方法

利用小波变换对平稳随机过程进行了谱分析,在小波变换的基础上给出了平稳随机过程的时—频功率谱及联合平稳随机过程的时—频互功率谱的概念,并详尽地研究了它们所具有的性质及与传统功率谱的关系。     

Analysis of CaSO4 scale formation mechanism in various nanofiltration modules

Scale formation of sparingly soluble salts has a significant effect on flux decline in nanofiltration (NF) system. This study focuses on the elucidation of the different mechanisms of scale formation according to membrane modules in NF system.In unstirred batch NF, flux decline was mainly due to surface (heterogeneous) crystallization, while in crossflow NF, fouling was attributed to both surface and bulk crystallization. However, the extent of contribution of each crystallization to the fouling depended on the NF modules. The bulk (homogeneous) crystallization followed by crystal deposition on the surface of the nanofilter played a major role in flux decline in the spiral wound module whereas surface blockage due to the surface crystallization does in the tubular module. When an on-line microfiler was introduced to prevent crystal deposition during the concentration run, flux improvement was pronounced only in case of the spiral wound module, whereas it was negligible in case of the tubular module. This was because the microfilter could only remove crystals formed in the retentate through the bulk crystallization which is the dominant fouling mechanism in the spiral wound module.A modified resistance-in-series model was applied to assess the fouling characteristics of each NF module based on the bulk and the surface crystallization. The greatest extent of the fouling due to surface crystallization in tubular module was attributed to its highest concentration polarization modulus compared with the other two modules at the same crossflow rate.     

Determination of lead in teeth of children for monitoring purposes by electrothermal atomic absorption spectrometry

A pilot study was carried out in order to establish proper sampling conditions and to verify a method for determination of lead in teeth suitable for monitoring long-term exposure of the population to lead. The population group in this study consisted of approximately 50 adults and 150 children (6–11 years). Only teeth without fillings were taken for analysis. After cleaning the teeth were dissolved in a mixture of HNO₃+H₂O₂. Conditions for the lead measurement by electrothermal atomic absorption spectrometry (Perkin Elmer 4100ZL) were optimized. Using a NH₄H₂PO₄ modifier, a pyrolysis temperature of 750°C and atomizing temperature of 1500°C were chosen for the determination. The calibration curve method has been used for evaluation. Results obtained in this pilot study indicate that the content of lead in teeth of children is lower than that of adults and depends on the type of tooth. In adults, in spite of a higher variability of lead concentration in different persons, the difference among lead contents in various teeth of one person is not significant.     

Cu/Al2O3催化剂的改性及其对NO选择性还原的催化性能

 以 γ-Al2O3 为载体,采用SO2-4进行改性并添加助剂La,再负载上Cu2+, 制备了改性的Cu/Al2O3催化剂(Cu/La/SO2-4/Al2O3),考察了SO2-4改性和助剂La对催化剂在富氧条件下催化丙烯选择性还原NO 反应的影响,并借助红外光谱、X射线衍射、扫描电镜、热重分析、程序升温还原和X射线光电子能谱等方法研究了改性催化剂的性能与结构的关系. 结果表明,改性催化剂的催化活性较高, NO转化率可高达83.7%. 采用SO2-4改性可促进催化剂表面的酸量增加,并促使产生B酸中心; 助剂La可提高Cu物种的分散程度,并提高催化剂的热稳定性和还原性,从而可有效提高催化剂在富氧条件下对丙烯选择性还原NO反应的催化活性和水热稳定性.