An investigation on the behavior of electrospun ZnO nanofibers under the application of low frequency AC electric fields

In present study, the behavior of electrospun ZnO nanofibers under the application of low frequency alternating (AC) electric fields within the range of 1 Hz–20 kHz was investigated using planar parallel electrodes. In the first stage, ZnO nanofibers with diameters up to 100 nm were prepared by electrospinning. At 1 Hz, the strong electric field-induced fluid flow due to charge redistribution around the electrode swept the fibers on the electrode surface farther from the edges. As the frequency was increased to 1 kHz, most depositing fibers accumulated on the electrode edges and in the meantime, a small fraction of them was pushed into the surface as a result of AC electroosmosis effect. Above 1 kHz, the fibers were assembled within the electrode gap bridging the interelectrode space. The dielectrophoresis force was considered responsible for the assembly and relative alignment of ZnO nanofibers above 1 kHz.     

Correlates of recency of eye examination among elderly African-Americans

The E2 gene of the branched-chain alpha-keto acid dehydrogenase (BCKDH) complex was studied at the molecular level in three patients with intermittent maple syrup urine disease (MSUD). All three patients had higher BCKDH activity than did those with the classical phenotype. In the first patient, a single base substitution from A to G in intron 8 created a new 5' splice site and caused an insertion of 126 nucleotides between exons 8 and 9 by activating an upstream cryptic 3' splice site in the same intron. The predicted mRNA encoded a truncated protein with 282 amino acids including 4 novel ones at the carboxyl terminus, compared with the normal protein with 421 amino acids. In vitro, the region from the patient but not from a normal control was recognized and was recovered as a novel exon, indicating that the single substitution was responsible for incorporation of the region into mRNA. This mutation probably supports an exon definition model in which the spliceosome recognizes a 3' splice site and then scans downstream for an acceptable 5' splice site, thereby defining an exon. The second patient was homozygous for a G to T transversion at nucleotide 1463 in exon 11, which predicted a substitution of the termination codon by a leucine residue and the addition of 7 extra amino acids at the carboxyl terminus. For each mutation, these two patients were homozygous and their parents were heterozygous. The third patient was a compound heterozygote for a C to G transversion at nucleotide 309 in exon 4 and a G to A transition at nucleotide 1165 in exon 9, causing an Ile-to-Met substitution at amino acid 37 and a Gly-to-Ser substitution at amino acid 323, respectively. Taken together, these results indicate that the molecular basis of intermittent phenotype MSUD in some patients can be due to mutations in the E2 gene, giving rise to a low but significant residual activity of the BCKDH complex.     

Application of Strong Porous Polymer Sheets for Superior Oil Spill Recovery

The usage of natural and synthetic sorbents in order to control oil spills is gaining increasing attention due to environmental concerns. In particular, polyolefins including polypropylene and polyethylene are the most commonly used oil sorbent materials because of their low cost but suffer from low oil absorption capacity. Attempts at trying to increase the surface‐to‐thickness ratio for improving uptake capacity makes them vulnerable to breakage and impractical for most oil spill applications. Novel super oil sorbent polymer sheets consisting of porous ultrahigh‐molecular‐weight polyethylene have been prepared. The presented sorbent exhibits extremely high uptake and retention capacities along with a mechanically strong structure. The combination of these factors as well as the cost effectiveness of the material used makes these sheets viable candidates for widespread production and utilization.     

Titania Nanostructures for Dye-sensitized Solar Cells

Nano-Micro Letters - Titania is one kind of important materials, which has been extensively investigated because of its unique electronic and optical properties. Research efforts have largely...     

节能发电调度研究综述

基于节能发电调度的基本原则,分析了节能发电调度的实施模式,针对调度时间的跨度长短、优化目标的不同及系统中机组类型的差异,分别综述了不同的节能发电调度模型,并介绍了现有节能发电调度的传统求解算法和智能算法,探讨了节能发电调度可能对电网和电力企业造成的影响并提出了应对措施,分析了深入推进节能调度可能存在的问题,为未来的研究英定了基础.     

Electrospinning preparation and characterization of cadmium oxide nanofibers

Using a facile synthesis route, cadmium oxide (CdO) nanofibers in the diameter range of 50–60 nm have been prepared employing the electrospinning technique followed by a single-step calcination from the aqueous solution of polyvinyl alcohol (PVA) and cadmium acetate dihydrate. Electron microscopy (EM) and the Brunauer–Emmett–Teller (BET) technique were employed to characterize the as-spun nanofibers as well as the calcined product. The specific surface area of the product was calculated to be 42.6711 m² g⁻¹. Infrared (IR) absorbance spectroscopy and X-ray powder diffractometery were conducted on the samples to study their chemical composition as well as their crystallographic structure. The study on the optical properties based on the photoluminescence (PL) spectrum demonstrated that the emission peaks of CdO nanofibers are centered at 493 and 528 nm. The direct bandgap of the CdO nanofibers was determined to be 2.51 eV.     

一种多准则综合的电压脆弱性评估方法

在现有的电力系统电压脆弱性评估方法中,存在单一指标难以反映全貌、基于权重的综合指标又过于主观的问题。文中根据已有的具有代表性的电压稳定指标,并结合节点重要性的信息,提出了基于超效率数据包络分析的多准则综合电压脆弱性评估方法以及相应的综合指标——相对电压脆弱性指标,用于辨识电网中的薄弱节点。在此基础上,还考虑了离群点的检验,以完善所提出的方法。最后,以江西电网作为算例进行了仿真分析,结果证明了所提出方法和指标的全面性、有效性和客观性。     

考虑用户停电损失的微网网架规划

基于对微网网架规划特点和用户停电损失的研究,建立了考虑用户停电损失的微网网架规划模型,并将分布式电源(DG)和负荷的时序特性纳入目标函数中,以最小化网络年费用为优化目标,综合考虑潮流约束、运行安全性约束、网络约束和可靠性约束。在Dijkstra形成初始网架后,采用改进的遗传算法求解模型。最后,将其应用于上海某居民小区29节点的微网网架规划中,得出了最优网架规划方案。