3-卤代吲唑水助质子转移反应机理的理论研究(英文)

在密度泛函B3LYP/6-311G**理论水平上,对气相和水相中3-卤代吲唑瓦变异构体进行几何构型伞自由度优化,获得它们在气相和水相中的几何结构和电子结构,PCM反应场溶剂模型用于水相计算.结果显示在气相和水相中,3.卤代吲唑的N1-H形式比N2-H形式稳定.探讨了不同的3-取代基团和溶剂化效应对互变异构体的几何结构,能量,电荷分布以及互变异构反应活化能的影响等.进一步研究了3-卤代吲唑水催化质子迁移的反应机理,提出了平面五元环的过渡态结构.     

Fine Mapping and Functional Analysis of Major Regulatory Genes of Soluble Solids Content in Wax Gourd (Benincasa hispida)

Soluble solids content (SSC) is an important quality trait of wax gourd, but reports about its regulatory genes are scarce. In this study, the SSC regulatory gene BhSSC2.1 in wax gourd was mined via quantitative trait locus (QTL) mapping based on high-density genetic mapping containing 12 linkage groups (LG) and bulked segregant analysis (BSA)-seq. QTL mapping and BSA-seq revealed for the first time that the SSC QTL (107.658–108.176 cM) of wax gourd was on Chr2 (LG2). The interpretable phenotypic variation rate and maximum LOD were 16.033% and 6.454, respectively. The QTL interval contained 13 genes. Real-time fluorescence quantitative expression analysis, functional annotation, and sequence analysis suggested that Bch02G016960, named BhSSC2.1, was a candidate regulatory gene of the SSC in wax gourd. Functional annotation of this gene showed that it codes for a NADP-dependent malic enzyme. According to BhSSC2.1 sequence variation, an InDel marker was developed for molecular marker-assisted breeding of wax gourd. This study will lay the foundation for future studies regarding breeding and understanding genetic mechanisms of wax gourd.     

大曲中产阿魏酸酯酶菌株的筛选及其特性分析

目的 从浓香型白酒大曲中分离筛选出一株产阿魏酸酯酶的菌株。方法 将大曲样品中筛选出的11株菌进行划线纯化培养,进一步挑选出产阿魏酸酯酶酶活较强的菌株并鉴定,分析其安全性及生物学特性,最后对发酵产酶条件进行优化。结果 得到一株产阿魏酸酯酶酶活较强的菌株为L-7,经鉴定为屎肠球菌(Enterococcus faecium)。经毒力基因检测、有害代谢产物实验结果均为阴性;生物学特性研究实验结果为:在16 h时生物量达到最大,耐最低pH为4,最高为11, NaCl质量分数为8%的条件下仍能生长,耐受最高的乙醇体积分数为13%;具有较好的安全性且有耐乙醇、耐盐、广泛的pH耐受性等优良性能。通过发酵产酶条件优化,该菌株产阿魏酸酯酶最佳发酵条件为:接种量为6%体积分数、培养温度32℃、转速160r/min、培养时间96 h;此时该菌株产阿魏酸酯酶的酶活为(44.68±0.05) U/L,较优化前提高了57.05%。结论 本研究结果可为产阿魏酸酯酶的菌株筛选提供参考,且筛选所得屎肠球菌在提高浓香型白酒及其他发酵食品中阿魏酸含量及风味具有应用潜力。     

Evaluation of the passivation effect and the first-principles calculation on surface termination of germanium detector

The point-contact high-purity germanium detector (HPGe) has the advantages of low background, low energy threshold, and high energy resolution and can be applie...     

Linear-Dispersion Division Multiple-Access for MIMO systems

Comprehensive study on novel Linear-Dispersion Division Multiple-Access（LDDMA） for multi-user uplink Multiple-Input Multiple-Output（MIMO）systems is proposed.In the new multiplexing scheme,each user’s information symbol is dispersed by a User-Specific Matrix（USM）both in space and time domain and linearly combined at base-station side.And a simple random search algorithm,based on capacity maximization criteria,is developed to generate a bank of USMs.Simulation results are presented to demonstrate the advantages of LDDMA.When the Bit Error Rate（BER） reaches 10^–3,the performance gains are 3dB and 5dB,compared with Time-Division Linear Dispersion Codes（TD-LDC）and BLAST,respectively.     

工程总承包项目的成本风险及其防范

本文在介绍国外EPC项目所面临的成本风险概念、类别和特点的基础上,提出了相应的防范措施,并探讨了项目履行过程中,根据FIDIC合同相关规定,针对如何降低成本风险提出了相应的建议,以供对外承包商参考.     

一种基于内容相似度和推荐反馈的信任模型

在已有P2P模型的基础上提出了基于内容相似度和推荐反馈计算节点推荐值的对等网络信用模型IPBS(Integrated-partial based similarity Trust).该模型利用节点间的内容相似度来评价节点提供推荐服务的能力,根据每次交易的内容不同而改变节点间相似度值;同时依据节点交易历史时间和推荐反馈值自适应动态地调整节点的推荐值;实例表明,IPBS节点间推荐值,通过参考节点内容相似度、交易历史时间和推荐反馈3种机制,加强了模型的动态适应能力和搜索服务的效率.     

Velocity and turbulence characteristics in an open channel with multi-row staggered vegetation patches

A staggered distribution of vegetation is very common in nature,which might significantly affect the flow structure.To investigate its impact,three rows of stag...     

A Review of Microfluidic Experimental Designs for Nanoparticle Synthesis

Microfluidics is defined as emerging science and technology based on precisely manipulating fluids through miniaturized devices with micro-scale channels and chambers. Such microfluidic systems can be used for numerous applications, including reactions, separations, or detection of various compounds. Therefore, due to their potential as microreactors, a particular research focus was noted in exploring various microchannel configurations for on-chip chemical syntheses of materials with tailored properties. Given the significant number of studies in the field, this paper aims to review the recently developed microfluidic devices based on their geometry particularities, starting from a brief presentation of nanoparticle synthesis and mixing within microchannels, further moving to a more detailed discussion of different chip configurations with potential use in nanomaterial fabrication.     

小型无人直升机的纵向横向解耦优化控制

论文根据小型无人直升机的机理建立了数学模型,并在悬停状态下近似线性化,运用Matlab的非线性控制工具箱(NCD)设计了具有很强鲁棒性的控制器,实现了对于小型无人直升机的纵向和横向的解耦控制,仿真结果证明了方法的有效性。