Development of Genetic Modification Tools for Hanseniaspora uvarum

Apiculate yeasts belonging to the genus Hanseniaspora are commonly isolated from viticultural settings and often dominate the initial stages of grape must fermentations. Although considered spoilage yeasts, they are now increasingly becoming the focus of research, with several whole-genome sequencing studies published in recent years. However, tools for their molecular genetic manipulation are still lacking. Here, we report the development of a tool for the genetic modification of Hanseniaspora uvarum. This was employed for the disruption of the HuATF1 gene, which encodes a putative alcohol acetyltransferase involved in acetate ester formation. We generated a synthetic marker gene consisting of the HuTEF1 promoter controlling a hygromycin resistance open reading frame (ORF). This new marker gene was used in disruption cassettes containing long-flanking (1000 bp) homology regions to the target locus. By increasing the antibiotic concentration, transformants were obtained in which both alleles of the putative HuATF1 gene were deleted in a diploid H. uvarum strain. Phenotypic characterisation including fermentation in Müller-Thurgau must showed that the null mutant produced significantly less acetate ester, particularly ethyl acetate. This study marks the first steps in the development of gene modification tools and paves the road for functional gene analyses of this yeast.     

加氢基础油的发展和市场前景

论述了世界９０年代润滑油加氢基础的发展态势和下世纪初的市场需求。并从新一代ＰＣＭＯ和ＡＦＴ对基础油的要求加氢基础油迅猛发展的必然趋势。     

一种ADS、Cadence软件联合仿真的LNA设计方法

为提高无线通信系统的接收灵敏度,低噪声放大器的设计尤为重要.基于Avago公司的高电子迁移率晶体管ATF54143芯片的2.4G～2.5G ISM频段范围低噪声放大器的设计,采用安捷伦公司的ADS软件设计、制作原理图并进行仿真,然后利用Cadence公司的Allegro SPB软件设计并制作原理图和PCB版图,最后将PCB版图导入到安捷伦公司的ADS系列软件中进行联合仿真,反复调整得到的仿真结果显示放大器工作在绝对稳定状态,噪声系数（NF）低于0.7,增益可达15dB.     

Cr涂层锆合金事故容错燃料包壳材料研究进展

自2011年日本福岛核事故后，事故容错燃料成为核电企业和相关科研机构的研究重点，旨在提升反应堆燃料系统的可靠性与安全性。锆合金包壳表面涂层技术是事故容错燃料研发的短期目标之一，其中，Cr涂层锆合金包壳为当前的主要技术路线。围绕涂层制备工艺、微观组织以及关键服役性能三方面，对Cr涂层锆合金的相关研究进展进行了综述。首先，对比介绍了锆合金表面金属Cr涂层制备工艺及其特点，涵盖了物理气相沉积、冷喷涂和3D激光熔覆等技术，同步介绍了国际核电巨头所采用的制备工艺及相关研发进展。其次，简单阐述了Cr涂层微观组织特征，重点阐述了正常运行工况下Cr涂层锆合金高温高压水腐蚀性能、高温高压水微动磨蚀性能、高温力学行为和辐照行为，以及事故工况下该材料体系高温内压爆破行为、高温蒸气氧化-淬火行为等，并同步针对其微观辐照机制、高温氧化/腐蚀机制等进行了归纳和深入分析。最后，对当前研究所存在的问题和未来发展方向进行了归纳分析。     

ATF对自动变速器工作性能的影响

现代汽车配用自动变速器的越来越多,使用中经常遇到自动变速器故障,这些故障与自动变速器油(ATF)有关,正确使用和检查ATF可以减少变速器故障,延长自动变速器使用寿命,所以在检查自动变速器油质时,不能忽视ATF对变速器性能的影响,通过实例分析从油液颜色、气味和所含杂质,推断出自动变速器的故障部位,从而快速排除故障,同时增强车辆用户对自动变速器的维护保养。     

Effects of overexpression of the alcohol acetyltransferase‐encoding gene ATF1 and disruption of the esterase‐encoding gene IAH1 on the flavour profiles of Chinese yellow rice wine

Alcohol acetyltransferase (AATase), which is mainly encoded by ATF1, is one of the most important enzymes for acetate ester synthesis. On the other hand, isoamyl acetate is degraded into a higher alcohol under the catalysis of IAH1‐encoded esterase. In this study, Chinese Saccharomyces cerevisiae was used as the parent strain to construct an ATF1 overexpression and IAH1 disruption mutant. The results show that after 5 days of pre‐fermentation, the concentrations of ethyl acetate, isoamyl acetate and isobutyl acetate in the yellow rice wines fermented with EY1 (pUC‐PIAK) increased to 468.94 mg L^?1 (which is approximately 22‐fold higher than that of the parent cell RY1), 99.86 and 7.69 mg L^?1 respectively. Meanwhile, isoamyl alcohol production was reduced to 56.37 mg L^?1 (which is approximately 50% of that produced by the parent strain RY1). Therefore, ATF1 overexpression and IAH1 disruption can significantly increase acetate esters contents and reduce isoamyl alcohol content in Chinese yellow rice wine, thereby paving the way for breeding an excellent yeast strain for high‐quality Chinese yellow rice wine production.     

基于小型盘盘型摩擦试验机的ATF油摩擦性能评定

提出采用小型盘盘型摩擦试验机(WAZAU)评价自动传动液(ATF)的抗颤性。采用WAZAU对2种ATF的抗颤性进行评价,并与传统的低速摩擦磨损试验机(LVFA)评价结果进行比较。结果表明:WAZAU与LVFA 2种摩擦试验机测得的摩擦特性曲线(摩擦因数-速度曲线)具有高拟合度,且试验后钢片表面发生摩擦化学反应成膜的主要成分也基本一致,从而证实2种摩擦试验机的试验结果具有很高的正相关性。WAZAU试验机是LVFA试验机的微型版,相比LVFA具有用油量小、操作简单的优点,且在检测噪声、震动、舒适性上比LVFA更具直观性,可作为快速模拟评价手段用于ATF的摩擦特性研究。     

电弧离子镀制备耐事故包壳材料厚Cr涂层及高温抗氧化性能

目的在Zr-4包壳材料表面制备具有耐事故高温性能的抗氧化厚Cr涂层,保护Zr基体,以防止与高温水蒸汽反应。方法采用自主研发的φ155 mm大弧源电弧离子镀技术在Zr-4合金表面制备约20μm的Cr涂层,通过X射线衍射仪(XRD)分析氧化前后的物相变化,通过扫描电子显微镜(SEM)和电子探针(EPMA)研究厚Cr涂层在不同温度下产生的多种缺陷,探究厚Cr涂层对Zr基体的防护机制。结果当涂层沉积速率3μm/h,制备的Cr涂层均匀致密,结合力优异,具有柱状晶结构,可经受至少15.8%的形变量,其抗塑性形变能力优异。沉积Cr层样品经过1000、1100、1200℃氧化,保温1h后快速冷却至室温,厚Cr涂层分化为Cr Ox层、Cr_2O_3层、残余Cr层和Cr-Zr扩散层。经受苛刻条件(1200℃/3600 s)测试,除保持连续性的氧化层外,在基体上仍残余良好结合的6.8μm Cr层。氧化层两次开裂阻止基体被进一步破坏。Cr-Zr扩散层是由Zr元素向Cr涂层方向渗透生长的。1200℃时,在基体近表面处产生的大尺寸隆起,是由于在近表面处韧性β-Zr(O)相转变为脆性α-Zr相,以及Cr偏聚贫Sn造成的。残余Cr层的柱状晶结构会形成Zr-O扩散通道,对涂层最后失效将起关键作用。结论 Zr合金包壳材料镀覆20μm的Cr涂层具有充分的耐事故能力,在严苛的事故条件测试下,各缺陷均未能使Zr-4合金基体暴露,涂层能够形成有效壁垒,防止锆合金基体暴露造成核事故,阻止基体进一步被破坏。     

The influence of lubricating oil on the performance of a metal V‐belt‐type continuously variable transmission

The influence of lubricating oil on the torque capacity and the efficiency of a continuously variable transmission (CVT) of metal V‐belt type were experimentally investigated using a commercial CVT unit with a belt assembly and pulley. In order to analyse the friction characteristics of each of the contacting parts in the CVT, a block‐on‐disc type friction testing machine was used. The maximum torque capacity between the belt and pulley in the actual CVT correlated with the friction coefficient under high contact pressure (200 MPa) and relatively high sliding velocity (0.1 m/s) on the friction testing machine. The transmission efficiency decreased as the load decreased. The maximum difference in the efficiency between all the commercial automotive transmission and CVT fluids tested reached 6%. It was found that the requirements for the efficiency of transmission at a lower load were in contradiction with the maximum torque capacity.