Synthesis of (−)-trachelanthamidine using a single electron transfer reaction in 1,4-dimethylpiperazine

Synthesis of (−)-trachelanthamidine, one of the pyrrolizidine alkaloids, has been achieved by using a single electron transfer reaction of 2-(2-acetoxyethenyl)-N-(trichloroacetyl)pyrrolidine in boiling 1,4-dimethylpiperazine as the key step.     

Ferroelectric Ionic Molecular Crystals with Significant Plasticity and a Low Melting Point: High Performance in Hot-Pressed Polycrystalline Plates and Melt-Grown Crystalline Sheets

Among ferroelectric crystals based on small molecules, plastic/ferroelectric crystals are currently receiving particular attention because they can be used as bulk polycrystals. Herein, we show that an ionic molecular ferroelectric crystal, guanidinium tetrafluoroborate, exhibits significant malleability and multiaxial ferroelectricity despite the absence of a plastic crystal phase. Powder samples of this crystal can be processed into transparent bulk crystalline plates either by press-forming or by melt-growing. The plates show high ferroelectric performance and related properties, demonstrating the largest hitherto reported spontaneous polarization for bulk polycrystals of small-molecule-based ferroelectrics. Owing to the ready availability of large-scale materials and processability into various bulk crystalline forms, this ferroelectric crystal represents a highly promising functional material that will boost research on diverse applications as bulk crystals.     

Chemical cleaning of oil contaminated polyethylene hollow fiber microfiltration membranes

The primary aim of this paper was to develop a more effective and economical procedure for cleaning polyethylene hollow fiber microfiltration membranes that have been used for removing oil from contaminated seawater. Alkaline cleaning showed higher recovery of operating cycle time but lower permeate flux recovery than acid cleaning. The combination of both alkaline and acid cleaning agents gave the best operating cycle time and flux recoveries (e.g. 96% and 94%, respectively). As the cleaning agent soaking time was reduced, the actual operating cycle time was reduced. However, the ratio of operating time/chemical cleaning time increased as the soaking time was reduced. The soaking time was recommended to be as short as possible (8–10 h) in the design of small capacity plants and 30 h or higher in case of large capacity plants. SEM analysis showed that in case of alkaline cleaning, most of the pores remained covered with a foulant layer, resulting in low flux recovery. The SEM results of acid cleaned membranes showed more complete removal of the foulant layer from the pores resulting in better flux recovery. Surface analysis of membranes cleaned with combined acid/base agents showed the best results. A membrane surface similar to the original one was obtained. The long-term objective is to increase the understanding of membrane fouling phenomena, preventive means and membrane cleaning processes as it applies to the clean-up and desalination of oil contaminated seawater.     

Direct photo-oxidation of benzene to phenol over Ti/Si binary oxide prepared by sol-gel method

Titanium-silicon (Ti/Si) binary oxides having a varying Ti content were prepared using the sol-gel method and used as photocatalysts. The photo-oxidation of benzene to phenol was carried out using Ti/Si binary oxide catalysts in the presence of benzene, water and gaseous oxygen. The amounts of benzene used hardly affected the phenol yield. On the other hand, the addition of sulfuric acid into reaction solution led to the improvement of phenol formation. The H₂O₂ formation rate seemed to be related to the phenol yeilds. The photocatalytic reactivity of Ti/Si binary oxide having different TiO₂ contents was investigated and it was found to be dramatically enhanced in the range of lower TiO₂ contents. XANES, ESR and XRD spectroscopic investigations of these Ti/Si binary oxide catalysts indicated that Ti species were highly dispersed in SiO₂ matrices and existed in a tetrahedral coordination. The photo-irradiation of catalysts having tetrahedral Ti species seemed to effectively lead to the formation of H₂O₂ as an intermediate.     

Electrochemical characterization of non-stoichiometric Cu2S x cathode for lithium batteries

Journal of Solid State Electrochemistry - Electrochemical performances of non-stoichiometric Cu2S x (1.25 ≤ x ≤ 0.625) cathodes prepared by spray...     

Estimating Functions for Nonlinear Time Series Models

This paper discusses the problem of estimation for two classes of nonlinear models, namely random coefficient autoregressive (RCA) and autoregressive conditional heteroskedasticity (ARCH) models. For the RCA model, first assuming that the nuisance parameters are known we construct an estimator for parameters of interest based on Godambe's asymptotically optimal estimating function. Then, using the conditional least squares (CLS) estimator given by Tjøstheim (1986, Stochastic Process. Appl., 21, 251–273) and classical moment estimators for the nuisance parameters, we propose an estimated version of this estimator. These results are extended to the case of vector parameter. Next, we turn to discuss the problem of estimating the ARCH model with unknown parameter vector. We construct an estimator for parameters of interest based on Godambe's optimal estimator allowing that a part of the estimator depends on unknown parameters. Then, substituting the CLS estimators for the unknown parameters, the estimated version is proposed. Comparisons between the CLS and estimated optimal estimator of the RCA model and between the CLS and estimated version of the ARCH model are given via simulation studies.     

Characterization of yttrium-doped ceria with various yttrium concentrations as cathode interlayers of SOFCs

This study focuses on enhancing the efficiency of solid oxide fuel cells (SOFCs) by modulating the thickness of the highly resistive solid solution layer of (Ce,Zr)O₂ formed between the yttria-stabilized zirconia (YSZ) electrolyte and the CeO₂-based interlayer on the cathode side. The effects of the concentration of dopant in CeO₂ on the thickness of the solid solution were analyzed. Yttrium-doped CeO₂ (YDC) interlayers were studied, with dopant concentrations in the range of 5–40 mol%. The results revealed that the thickness of the solid solution decreased with increasing dopant concentration up to 20 mol% and then saturated at higher dopant concentrations. In addition, the electrical conductivities of yttrium-doped ceria (YDC) and the solid solution of YSZ and YDC were measured. YDC with a dopant concentration of 20 mol% exhibited the highest conductivity. The conductivities of the YSZ/YDC solid solution decreased compared to those of YDC and YSZ for each dopant concentration, and the extent of the reductions was approximately the same for all dopant concentrations. These results indicate that a dopant concentration of 20 mol% is optimal to minimize the internal resistance of SOFCs when YDC is used as the interlayer material.     

电感耦合等离子体原子发射光谱法(ICP-AES)测定硫化物矿石中的14种常微量元素

采用高压消解罐-王水溶样前处理硫化物矿石样品,ICP-AES法测定了硫化物矿GBW07163标准物质中的14种常微量元素的含量,确定了最佳工作条件,选择了最佳分析谱线。实验结果表明,方法线性相关系数良好,可同时测定硫化物矿石中的常微量元素,方法检出限低,精密度高,分析结果与标准值相吻合,可以满足地矿检测的需求。     

SiO2 Fibers of Two Lengths and Their Effect on Cellular Responses of Macrophage-like Cells

The immunoreactivity or/and stress response can be induced by nanomaterials’ different properties, such as size, shape, etc. These effects are, however, not yet fully understood. This study aimed to clarify the effects of SiO₂ nanofibers (SiO₂NFs) on the cellular responses of THP-1-derived macrophage-like cells. The effects of SiO₂NFs with different lengths on reactive oxygen species (ROS) and pro-inflammatory cytokines TNF-α and IL-1β in THP-1 cells were evaluated. From the two tested lengths, it was only the L-SiO₂NFs with a length ≈ 44 ± 22 µm that could induce ROS. Compared to this, only S-SiO₂NFs with a length ≈ 14 ± 17 µm could enhance TNF-α and IL-1β expression. Our results suggested that L-SiO₂NFs disassembled by THP-1 cells produced ROS and that the inflammatory reaction was induced by the uptake of S-SiO₂NFs by THP-1 cells. The F-actin staining results indicated that SiO₂NFs induced cell motility and phagocytosis. There was no difference in cytotoxicity between L- and S-SiO₂NFs. However, our results suggested that the lengths of SiO₂NFs induced different cellular responses.