功率金属-氧化物半导体场效应晶体管静电放电栅源电容解析模型的建立

在实际静电放电测试时,发现各种功率金属-氧化物半导体场效应晶体管(MOSFET)的静电放电测试结果均呈现出正反向耐压不对称现象,而人体与器件接触时的静电放电过程是不区分正反向的.正反向耐压差异较大对于功率MOSFET或作为静电放电保护器件来说都是无法接受的,其造成器件失效的问题格外凸显.本文通过建立SGT-MOSFET,VUMOSFET和VDMOS在静电放电正反向电压下的栅源电容解析模型,对比分析了三种功率MOSFET器件静电放电正反向耐压不对称及其比值不同的原因,为器件的静电放电测试及可靠性分析提供了理论依据.

利用高密度Bin遗传图谱定位水稻抽穗期QTL

挖掘新的控制水稻抽穗期相关位点和候选基因,对抽穗期的遗传机制研究和品种改良具有重要的意义。利用抽穗期存在明显差异的粳稻TD70和籼稻Kasalath杂交衍生的包含186个家系的重组自交系群体,构建了基于深度重测序的高密度Bin遗传图谱,图谱共包含12,328个Bin标记。RIL群体及亲本2018年和2021年正季种植于江苏省南京市江苏省农业科学院。以家系从播种到抽穗所经历的天数作为抽穗期表型值,使用IciMapping软件3.4版的完备区间作图法,对控制水稻抽穗期的QTL进行鉴定。2年共检测到15个抽穗期的QTL,分布在3号、6号、7号、8号、10号和12号染色体上,LOD值为2.58~10.68,其中7个QTL和已知抽穗期QTL的位置存在重叠或者部分重叠。共有4个QTL在2年均检测到,表现出较强的稳定性。对2年重复鉴定到的4个QTL区间进行基因功能注释和亲本间序列分析,共发现7个注释有功能,且在2个亲本间编码区存在非同义突变的基因。根据候选基因SNP的类型对RIL群体家系进行基因等位型分类和效应分析,发现4个基因其不同等位型的RIL家系在抽穗期上存在显著或者极显著差异,推测可能为候选基因,可用于后续水稻抽穗期的分子机制研究。

低谷蛋白半糯型粳稻品种(品系)的氨基酸组分含量及淀粉理化性质

氨基酸含量是评价稻米营养品质的重要指标之一,提高稻米中的氨基酸含量,尤其是提高赖氨酸等必需氨基酸含量是提高稻米品质的重要目标。低谷蛋白半糯型粳稻品种是一种具有低直链淀粉含量、低谷蛋白含量特性的新型粳稻品种,适合肾病患者食用。为了明确低谷蛋白半糯型粳稻品种(品系)的氨基酸组分含量与淀粉理化特性,以低谷蛋白半糯型粳稻品种(品系)为材料,半糯型粳稻、普通粳稻品种为对照,在相同生态环境和栽培条件下种植3种不同类型的粳稻品种(品系)共16个,测定并分析稻米总氨基酸含量及各氨基酸组分含量,同时分析直链淀粉含量、糊化温度、胶稠度等淀粉理化特征,并进一步分析氨基酸组分含量与淀粉理化指标的相关性。结果表明,3种类型粳稻品种(品系)间的总氨基酸、赖氨酸、苏氨酸及谷氨酸含量存在显著差异,低谷蛋白半糯型粳稻的总氨基酸、赖氨酸的平均含量显著低于半糯型粳稻、普通粳稻,半糯型粳稻谷氨酸的平均含量显著高于低谷蛋白半糯型粳稻、普通粳稻。低谷蛋白半糯型粳稻的崩解值显著低于半糯型粳稻、普通粳稻,半糯型粳稻的胶稠度与峰值黏度显著高于普通粳稻、低谷蛋白半糯型粳稻;赖氨酸、苏氨酸含量与峰值黏度、食味值呈显著或极显著负相关,与硬度呈显著或极显著正相关。3种不同类型粳稻品种(品系)在赖氨酸含量、直链淀粉含量和崩解值上存在显著差异,其中低谷蛋白半糯型粳稻品种(品系)的赖氨酸含量最低,半糯型粳稻品种具有较低的直链淀粉含量、消减值和回复值,同时具有较高的谷氨酸含量、胶稠度和崩解值。17种氨基酸中,赖氨酸含量对米饭食味品质的影响最大,与米饭的外观、黏度和食味值呈极显著负相关。

逆阻型IGCT驱动器关断电路的杂散电感研究

随着国内“双碳”战略的快速推进,特高压直流输电得到持续发展。为解决传统高压直流(HVDC)中存在的换相失败等问题,采用关断电流能力强的全控逆阻型IGCT(RB-IGCT),开发电流源型换流器(CSC)是最佳选择,而门极驱动器的性能直接影响到RB-IGCT器件性能的优劣。因此,此处主要针对RB-IGCT驱动器的关断电路,采用DirectFet替代塑封MOSFET,对环绕型RB-IGCT的印制电路板(PCB)布局进行优化,研究了DirectFet封装对电路杂散电感的影响。实测结果表明,与塑封MOSFET相比,采用DirectFet可以使关断回路的电流上升率提高26%,从而提升了IGCT的最大关断电流能力。

高压IGBT雪崩鲁棒性的研究

随着绝缘栅双极晶体管(insulated gate bipolar transistor,IGBT)电压等级的提升和电流容量的增大,雪崩效应已成为限制器件安全工作区(safe operating area,SOA)的重要因素.雪崩发生后IGBT背面p+n结的空穴注入是其雪崩效应区别于其他器件的主要特征.本文通过理论分析与数值模拟的方法研究了IGBT雪崩击穿特性以及雪崩产生电流丝的性质,揭示了控制雪崩产生电流丝性质的物理机制.结果表明IGBT背面的空穴注入导致其雪崩击穿曲线上产生额外的负微分电阻分支;器件共基极电流增益α_(pnp)是决定雪崩产生电流丝的关键因素,随着α_(pnp)的增大,雪崩产生的电流丝强度越强、移动速度越慢,从而导致器件的雪崩鲁棒性越弱.

SGT-MOSFET电场解析模型的建立

屏蔽栅沟槽金属氧化物半导体场效应晶体管(SGT-MOSFET)在体内引入了纵向接源电极的屏蔽栅极,可以辅助耗尽漂移区,其耐压原理与沟槽MOSFET(VUMOSFET)不同.本文以110 V左右结构的SGTMOSFET为研究对象,通过数值仿真、理论分析以及解析建模,研究了不同结构的耐压原理以及结构参数与电场强度分布的相关性;建立了与器件各个结构参数相关的电场解析模型,为器件结构设计提供了理论依据;并引入雪崩载流子对小电流下的电场解析模型进行了修正,使得解析结果和仿真结果吻合较好;通过修正后的电场解析模型提取了最优电场下的场氧厚度,使得相应产品的静、动态特性得到明显改善,从而极大地提升了器件的性能.

优良食味半糯粳稻品质标准的研制与应用

优良食味半糯粳稻是指稻米直链淀粉含量为8%~13%,含有低直链淀粉含量的Wx等位基因(如Wx^(mp)、Wx^(mq)、Wx^(mv)等)、食味值在80分以上的粳稻。现行国家标准和行业标准均没有关于半糯粳稻品质评价的具体指标,亟需制订优良食味半糯粳稻的品质标准。在调研中国关于粳稻稻谷和粳稻稻米现有国家和行业标准、分析近4年已审定和参加区域试验的半糯粳稻品种(系)品质的理化指标的基础上,制定了优良食味半糯粳稻品质标准,为半糯粳稻品种的选育、鉴定、评价和推广提供理论依据。

CRISPR/Cas9编辑GS3和qGL3基因创制大粒水稻新种质

CRISPR/Cas9基因编辑技术已成为植物新种质创制和性状定向改良的重要手段。GS3和qGL3是调控水稻籽粒伸长的主效基因,功能缺失后产生大粒表型。本研究拟以小粒型粳稻品种南粳5055为试验材料,对GS3和qGL3基因进行编辑,以期获得能稳定遗传的大粒水稻新种质。利用CRISPR/Cas9系统构建了分别携带GS3-gRNA和qGL3-gRNA双靶点的pYLCRISPR/Cas9编辑载体,通过农杆菌介导的遗传转化法,成功获得了GS3和qGL3基因编辑植株,编辑效率分别为90.0%和88.9%。与南粳5055相比,GS3编辑植株在T2、T3世代中平均粒长增幅约9.0%,千粒重增幅平均为12.7%,每穗粒数降低约9.3%,穗数、穗长、结实率和单株产量差异不明显;qGL3编辑植株的粒长增幅约21.0%,千粒重增幅平均为31.7%,每穗粒数降低约31.5%,且穗数表现出增加而结实率表现降低趋势,而穗长和单株产量差异不明显。qGL3基因对粒形和粒重的贡献明显大于GS3。综上所述,通过CRISPR/Cas9技术编辑南粳5055的GS3和qGL3基因,获得了一系列大粒水稻新种质,该结果为水稻粒形改良研究提供了重要参考。

水稻超大籽粒形成的重要基因和调控通路的转录组分析

以特大粒水稻品系TD70和小粒籼稻品种Kasalath不同发育时期的幼穗为材料,进行转录组测序。将获得的干净读长(Clean read)以日本晴(Nipponbare)基因组序列为参考序列进行比对得到唯一读长(即特异比对到参考基因组的read),利用FPKM(Fragments per kilobase of transcript per million fragments mapped)法计算基因的表达水平,用GO和KEGG数据库对差异表达基因(Differentially expressed genes,DEGs)进行功能注释、富集和代谢通路分析。结果表明,在水稻幼穗发育的早、中、后3个时期分别获得3618个、4183个和5254个差异表达基因,共有4374个差异表达基因得到基因本体(Gene ontology,GO)功能注释,主要涉及DNA结合、细胞进程、信号转导、细胞增殖、物质转运等方面。KEGG数据库分析结果显示,差异表达基因共涉及119条代谢通路,主要包括淀粉和蔗糖代谢通路、内质网中的蛋白质加工通路、激素信号转导通路、细胞周期蛋白通路等。

论大学生创新创业对提升自身竞争优势的影响

由于我国人口众多,社会压力大,各方面竞争也很强。为了适应社会发展需求,必须为社会培养社会需要能力强、知识面广的复合型人才。那么如何提升相关能力,如何提升竞争优势,这两个问题之间可以说有着千丝万缕的联系,而大力支持大学生创新创业的方式则可以作为一个良好的解决问题的办法。

面向HVDC应用的逆阻型IGCT控制保护功能研究

特高压直流输电(HVDC)作为电力传输的重要部分,在国家实现“双碳”目标的驱动下快速发展。大功率逆阻型集成门极换流晶闸管(IGCT)作为HVDC换流阀的核心器件,在阀上应用时需要进行串联以提升其功率容量。为解决IGCT串联使用时系统启动可靠性及功率控制问题,采用启动双模式闭锁及驱动供电多模式控制等方法,实现了阀上器件启动保护及供电功率的有效控制,实验结果表明,具备实际应用的良好效果。

掺氢天然气环境下管道钢氢脆行为研究进展

为推动我国掺氢天然气管道的发展,综述了目前含氢气环境下管道钢氢脆的研究成果,总结了温度、压力、掺氢比等运行条件对钢材氢脆的影响,分析了钢材强度、微观组织、氢陷阱等材料性质与管道钢氢脆行为之间的联系,归纳了预防和抑制管道钢氢脆行为的方法。笔者认为,当前亟待解决的科学技术问题包括进一步探究掺氢天然气管道环境下不同运行条件对管道钢氢脆行为的影响规律;确定掺氢天然气管道的安全运行温度、压力、掺氢比等关键参数;建立不同服役条件下掺氢天然气管道输送的安全评价方法,完善掺氢天然气管道与现役管道相容性评价体系;形成掺氢天然气管道的设计规范和相关标准;开展气体抑制剂和阻氢涂层等抗氢脆方法的评价。

膜技术纯化枸杞多糖的试验研究

为精制枸杞多糖(Lyeium barbarum Polysaccharide,LBP),并获得可靠的工艺参数,为工业化生产的实现提供必要的数据积累和依据。本文采用高速离心和膜技术相结合的试验方法对枸杞水提液进行处理,选用截留分子量为 1×10^4的超滤膜浓缩纯化 LBP,并用硫酸-苯酚显色法测定截留液和透过液多糖的含量。结果表明:操作时间和操作压力对膜通量有较大的影响。在料液温度 25 ℃、操作压力 0.8 MPa 条件下,对枸杞水提的第一汁、第二汁和合并液超滤 4~5 h,所得截留液干燥快速,其多糖含量分别为 15.51%、8.36%和 14.24%。因此,采用膜技术分离枸杞水提液的工艺操作简单,能耗小,纯化效果较显著,所得成品性状好,适用于工业化生产。

Characterization of eating quality and starch properties of two Wx alleles japonica rice cultivars under different nitrogen treatments

To understand the effect of nitrogen(N) fertilizer on rice(Oryza sativa L.) eating and cooking quality(ECQ). Here, we investigated the ECQ attributes, physicochemical foundation of ECQ, and amylopectin fine structure of two Waxy(Wx) alleles japonica rice cultivars Nanjing 9108(NJ9108) and Huaidao 5(HD5) under four N rates(0, 150, 300, and 450 kg ha^-1). Sensory and pasting properties of the two cultivars varied depending on N rates. Compared with the control(0 kg ha^-1), the overall eating quality and sensory value were significantly decreased under the N rates of 300 and 450 kg ha^-1. Further, conventional descriptive analysis showed that the stickiness and retrogradation of cooked rice were significantly decreased. These results indicated that application of N fertilizer seems to affect the texture of cooked rice, causing it to be less sticky, lowering its retrogradation, and consequently reducing its palatability. Results from rapid visco analyzer(RVA) revealed that the peak and breakdown viscosities significantly decreased, while the setback viscosity and peak time increased under the N rates of 300 and 450 kg ha^-1. However, no significant difference was observed when the N rate was 150 kg ha^-1, indicating that less N fertilization can maintain rice ECQ. As the N rate increasing, protein content increased, whereas apparent amylose content, starch content, and gel consistency almost unchanged. Interestingly, compared with the control, under N treatments, the percentage of short amylopectin branches in NJ9108 was decreased, but increased in HD5, as controlled by amylopectin synthesis-related genes. Notably, SSI and BEIIb were down-regulated in NJ9108, whereas BEIIb was up-regulated in HD5. Thus, the palatability of both rice cultivars was significantly decreased under excessive N fertilization as a consequence of reduced stickiness and retrogradation of the cooked rice, which might have resulted from an elevated protein content and altered amylopectin fine structure. In addition, amylopectin synthesis appeared to be affected by N fertilizer and the genotype of the rice cultivar.

Research progress on the breeding of japonica super rice varieties in Jiangsu Province,China

In this study we report the results of a decade-long breeding program for japonica super rice made by Nanjing Branch of Chinese National Center for Rice Improvement in Jiangsu Academy of Agricultural Sciences. We concluded that selection of parents with good comprehensive traits and complementary advantages and disadvantages of both parents in the hybrid combination, and early selection of high heritability traits in earlier segregating generations could significantly improve the breeding efficiency. The use of closely-linked functional markers in pyramiding of multiple genes could greatly increase breeding efficiency, avoiding time-consuming and laborious steps that were used in traditional breeding program. It is also important to coordinate the yield components with variety characteristics such as yield stability, wide adaptability, lodging resistance, and an attractive grain appearance during late growth stage of rice.

Cluster Analysis on Japonica Rice(Oryza sativa L.) with Good Eating Quality Based on SSR Markers and Phenotypic Traits

Diversity of 60 conventional japonica rice accessions with good eating quality at home and abroad was analyzed using SSR molecular markers, agronomic traits and taste characteristics. A total of 290 alleles were detected in the 60 accessions at 72 SSR loci with the high similarity coefficients varying between 0.600 and 0.924. The loci on chromosome 5 showed the greatest value in average allele number. Additionally, most of the SSR loci could detect 3 to 4 alleles. An UPGMA dendrogram based on the cluster analysis of the genetic similarity coefficients showed that the grouping trend of part of the rice accessions was geographic-related and most of the rice accessions in Jiangsu Province, China were clustered together. Furthermore, many domestic accessions from south and north origins in China were close to the foreign japonica rice varieties, as proved by their pedigree origin from the foreign high-quality sources. For taste characteristics, part of the accessions with excellent taste were clearly clustered into one category though they came from different geographical regions, which indicates that taste characteristics of some varieties were mainly genetically determined. In addition, the agronomic traits of japonica rice with good taste might be closely related with their geographical origins, but the relationship between superior taste characteristics and agronomic traits should be further clarified.

Genetic Improvement of Japonica Rice Variety Wuyujing 3 for Stripe Disease Resistance and Eating Quality by Pyramiding Stv-b^i and Wx-mq

Japonica rice variety Kanto 194 as the donor of resistance gene Stv-b^i and Iow-amylose content gene Wx-mq was used to improve the resistance and eating quality of Wuyujing 3 by the breeding strategy of backcross. In continuous backcross and selfcross generations, the related molecular markers with Stvobi and Wx-mq genes were utilized for genotypic detection by associated with resistance identification of rice stripe disease and agronomic traits selection. Finally, 10 improved lines with homozygous genotype Stv-b^i Stv-b^iWx-mqWx-mq were obtained from BC3F4 generation. The results of comparative analysis indicated that most characters of these lines were consistent with those of recipient parent Wuyujing 3, except for the improved resistance, appearance and eating quality. By evaluation of the comprehensive performance of them, two excellent lines K01 and K04 were selected for further experiments.

Inheritance Analysis and QTL Mapping of Rice Starch Viscosity (Rapid Visco Analyzer Profile) Characteristics

The rice starch viscosity characteristics, which can be indicated by Rapid Visco Analyzer profile （RVA profile）, have been proved useful for the evaluation of cooking and eating quality in rice breeding program. To study the inheritance of the RVA profile, an F2 population of Wuyujing 3/Aichi 106 was used. The results indicated that the peak viscosity （PKV） was a typical quantitative character, and the hot paste viscosity （HPV）, cool paste viscosity （CPV）, setback viscosity （SBV）, breakdown viscosity （BDV）, and consistence viscosity （CSV） might be controlled by one major gene and several minor genes To elucidate the genetic basis of the paste viscosity characteristics, a recombinant inbred line （RIL） population derived from Nikken 2/Milyang 23 and its genetic linkage map were used to map the QTLs controlling RVA profiles in 2005 and 2006. A total of 34 QTLs distributed on chromosomes 1,2, 3, 4, 6, 7 and 8 were detected, including 19 and 15 QTLs in 2005 and 2006 respectively. Eight QTLs were both detected in the two years, qHPV6, qCPV6, qCSV6, qSBV6, and qBDV6 were located on chromosome 6, while qHPV2, qCSV2, and qCPV2were on chromosome 2.

QTL Mapping for Grain Size Traits Based on Extra-Large Grain Rice Line TD70

Grain size traits, including grain length, grain width and grain thickness, are controlled by quantitative trait loci （QTLs）. Many QTLs relating to rice grain size traits had been reported, but their control mechanisms have not yet been elucidated. A recombinant inbred line （RIL） population of 240 lines, deriving from a cross between TD70, an extra-large grain size japonica line with 80 g of 1000-grain weight, and Kasalath, a small grain size indica variety, were constructed and used to map grain size QTLs to a linkage map by using 141 SSR markers in 2010 and 2011. Five QTLs for grain length, six for grain width and seven for grain thickness were detected distributing over chromosomes 2, 3, 5, 7, 9 and 12. Seven QTLs, namely qGL3.1, qGW2, qGW2.2, qGW5.1, qGW5.2, qGT2.3 and qGT3.1, were detected in either of the two years and explained for 56.19%, 4.42%, 29.41%, 10.37%, 7.61%, 21.19% and 17.06% of the observed phenotypic variances on average, respectively. The marker interval RM1347-RM5699 on chromosome 2 was found common for grain length, grain width and grain thickness; qGL3.1 and qGT3.1 were mapped to the same interval RM6080-RM6832 on chromosome 3. All 18 QTL alleles were derived from the large grain parent TD70. Most of the QTLs mapped in the present study were found the same as the genes previously cloned （GW2, GS3 or qGL3, GW5 and GS5）, and several were the same as the QTLs （GS7 and qGL-7） previously mapped. Three QTLs, qGL2.2 on chromosome 2, qGW9 and qGT9 on chromosome 9, were first detected. These results laid a foundation for further fine mapping or cloning of these QTLs.

Transferring Translucent Endosperm Mutant Gene Wx-mq and Rice Stripe Disease Resistance Gene Stv-bi by Marker-Assisted Selection in Rice (Oryza sativa)

A high-yielding japonica rice variety, Wuyunjing 7, bred in Jiangsu Province, China as a female parent was crossed with a Japanese rice variety Kantou 194, which carries a rice stripe disease resistance gene Stv-b＇ and a translucent endosperm mutant gene Wx-mq. From F2 generations, a sequence characterized amplified region （SCAR） marker tightly linked with Stv-b＇ and a cleaved amplified polymorphic sequence （CAPS） marker for Wx-mq were used for marker-assisted selection. Finally, a new japonica rice line, Ning 9108, with excellent agronomic traits was obtained by multi-generational selection on stripe disease resistance and endosperm appearance. The utilization of the markers from genes related to rice quality and disease resistance was helpful not only for establishing a marker-assisted selection system of high-quality and disease resistance for rice but also for providing important intermediate materials and rapid selection method for good quality, disease resistance and high yield in rice breeding.