换热管直径对换热器(火用)效率影响的探讨

本文通过换热管直径对换热器(火用)效率影响的分析,提出了换热器设计及改造时,减小(火用)损失的一条途径.     

Metal microparticle – Polymer composites as printable,bio/ecoresorbable conductive inks

Biologically and environmentally resorbable electronic devices support application possibilities that cannot be addressed with conventional technologies. This paper presents highly conductive, water-soluble composites that can be printed to form contacts, interconnects, antennas, and other important features that are essential to nearly all systems of this type. An optimized material formulation involves in situ polymerization to yield a polyanhydride containing a dispersion of molybdenum microparticles at appropriate concentrations. Comparisons of essential physical and electrical properties of these materials to those of composites formed with other polymers and other metal microparticles reveal the relevant considerations. Various functional demonstrations of screen-printed test structures and devices illustrate the suitability of these conductive inks for use in water-soluble electronic devices. A key advantage of the material introduced here compared to alternatives is its ability to maintain conductance over significant periods of time while immersed in relevant aqueous solutions. Studies involving live animal models establish the biocompatibility.     

Hierarchical porous onion-shaped LiMn<Subscript>2</Subscript>O<Subscript>4</Subscript> as ultrahigh-rate cathode material for lithium ion batteries

Spinel LiMn₂O₄ is a widely utilized cathode material for Li-ion batteries. However, its applications are limited by its poor energy density and power density. Herein, a novel hierarchical porous onion-like LiMn₂O₄(LMO) was prepared to shorten the Li⁺ diffusion pathway with the presence of uniform pores and nanosized primary particles. The growth mechanism of the porous onion-like LiMn₂O₄ was analyzed to control the morphology and the crystal structure so that it forms a polyhedral crystal structure with reduced Mn dissolution. In addition, graphene was added to the cathode (LiMn₂O₄/graphene) to enhance the electronic conductivity. The synthesized LiMn₂O₄/graphene exhibited an ultrahigh-rate performance of 110.4 mAh·g^–1 at 50 C and an outstanding energy density at a high power density, maintaining 379.4 Wh·kg^–1 at 25,293 W·kg^–1. Besides, it shows durable stability, with only 0.02% decrease in the capacity per cycle at 10 C. Furthermore, the (LiMn₂O₄/graphene)/graphite full-cell exhibited a high discharge capacity. This work provides a promising method for the preparation of outstanding, integrated cathodes for potential applications in lithium ion batteries.

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Mutations in the ligand-binding domain of the kit receptor: an uncommon site in human piebaldism

Heterozygous mutations in the gene for the Kit transmembrane receptor have been identified recently in human piebaldism and mouse "dominant spotting." Interestingly, all of the 14 known missense mutations that cause depigmentation in these species map to the tyrosine kinase domain of the receptor, whereas none have involved the extracellular ligand-binding domain. In an attempt to detect these uncommon mutations, we screened the nine exons encoding the extracellular portion of Kit for single-strand conformation polymorphisms (SSCP) in eight piebald subjects previously reported to be negative for kinase mutations. Four of these eight kindreds proved to carry novel mutations. The first mutation, found in two apparently unrelated probands with mild piebaldism and English ancestry, substitutes an arginine for a highly conserved cysteine at codon 136. This substitution disrupts a putative disulfide bond required for formation of the second Ig-like (D2) loop of the Kit ligand-binding domain. The second mutation, detected in a piebald kindred characterized by unusually limited depigmentation, substitutes a threonine for an alanine at codon 178, a site just proximal to conserved cysteines at codons 183 and 186. The third mutation, occurring in a kindred with more extensive depigmentation, is a novel four-base insertion in exon 2 that results in a proximal frameshift and premature termination. The data strongly suggest that piebaldism can result from missense mutations in the Kit ligand-binding domain, although the resulting phenotype may be milder than that observed for null or kinase mutations. The apparent clustering of these uncommon mutations at or near the conserved cysteines for the D2 Ig-like loop further suggests a critical role for this region in Kit receptor function.     

SYSNTHESIS AND CHARACTERIZATION OF A NEW COMPOUND K_6Ti_2Nb_(14)O_(42)IN K_2O-TiO_2-Nb_2O_5SYSTEM

A new compound K_6Ti_2Nb_(14)O_(42)was found inthe ternary system K_2O-TiO_2-Nb_2O_5.The compound was char-acterized and investigated by electron,probe,X-ray powderdiffraction and differential thermal analysis.The transpar-ent crystal of light yellow color in form of hexagon-thinplate can be grown by flux method.Further,its crystal struc-ture was determined by four-circle diffratometer K_6Ti_2Nb_(14)O_(42)crystallizes in he(?)(?)(?)onal system with unitcell parameters a=9.1106(5)×10~(-10)m·c=12.0136(9)×10~(-10)m,Z=l andspace.group P6_3/mcm(193).     

胰岛素对初发2型糖尿病的疗效及影响

目的:观察胰岛素对初发2型糖尿病的疗效及不良反应,以及对血糖的影响.方法:选择2008年1月至2010年1月在我院住院的T2DM患者为观察对象.120例初发2型糖尿病患者随机分为治疗组和对照组各60例,治疗3个月后,观察治疗的疗效及对血糖控制情况.结果:治疗组的疗效优于对照组,且治疗组血糖控制效果明显优于对照组,差异有统计学意义(P＜0.05).结论:胰岛素对初发2型糖尿病疗效确切,更好地降低T2DM血糖水平,值得基层医院广泛推广和应用.     

计及数据不平衡的RUSBoost-LightGBM 短期负荷预测方法

随着人工智能技术的发展,负荷预测的准确度显著提高,但仍有一些负荷曲线预测精度较低。造成这种现象的原因 在于训练集中这类负荷曲线属于少数类,导致数据不平衡,模型无法充分学习,从而影响了预测的精度。为解决电力负荷数 据不平衡问题导致的预测精度降低的问题,提出了一种先分类后预测的解决方法。通过改进的K-Mediods 方法把具有高相 似性的历史负荷曲线进行聚类,并构造分类标签与电力负荷的特征集;然后根据预测时间的特征进行分类,通过RUSBoost 算 法很好的优化了分类过程中数据不平衡问题;最后在每类中使用LightGBM算法进行负荷预测。在公开数据集上的实验表 明,所提出方法对少数类负荷的预测效果显著,其平均绝对百分比误差(MAPE) 为2.95%,均方根误差(RMSE) 为 175.71 MW;对于常规负荷的预测,MAPE为3 .52%,RMSE为195.84 MW,相对其他方法也具有较好的预测效果。     

一种高精度圆柱形人工边界条件:水-柱体相互作用问题

针对水-柱体动力相互作用问题,提出一种用于模拟无限域水体的圆柱形高精度时域人工边界条件。首先,基于三维可压缩水体的波动方程和边界条件,采用分离变量法建立了时空全局的精确人工边界条件;然后,将其动力刚度表示为外域模型和波导模型人工边界条件动力刚度的嵌套形式;之后,应用时间局部化方法得到时间局部的高精度人工边界条件;最后,离散高精度人工边界条件,并将其与近场有限元方程耦合,形成一种能够采用显式时间积分方法求解的时间二阶常微分方程组。数值算例表明:提出的三维圆柱形高精度人工边界条件精确、高效、稳定。     

Effect of Seed Layer on the Orientation of Zinc Oxide Film on Silicon Substrate

1. IntroductionZinc oxide films have been attracting more and moreattention because of their high diffractive index, low resis-tance, and photoluminescence properties, and are beingused as transparent electrodes, basis material for opti-cal wave guide devices, gas sensors and so on. Manymethods have been developed to prepare ZnO films, suchas chemical vapor deposition[1], reactive evaporation[2],pulsed laser ablation[3], sputtering[4], spray pyrolysis[5]and hydrothermal method[6]. There are a…