The Plastidial DIG5 Protein Affects Lateral Root Development by Regulating Flavonoid Biosynthesis and Auxin Transport in Arabidopsis

To reveal the mechanisms underlying root adaptation to drought stress, we isolated and characterized an Arabidopsis mutant, dig5 (drought inhibition of lateral root growth 5), which exhibited increased sensitivity to the phytohormone abscisic acid (ABA) for the inhibition of lateral root growth. The dig5 mutant also had fewer lateral roots under normal conditions and the aerial parts were yellowish with a lower level of chlorophylls. The mutant seedlings also displayed phenotypes indicative of impaired auxin transport, such as abnormal root curling, leaf venation defects, absence of apical hook formation, and reduced hypocotyl elongation in darkness. Auxin transport assays with [³H]-labeled indole acetic acid (IAA) confirmed that dig5 roots were impaired in polar auxin transport. Map-based cloning and complementation assays indicated that the DIG5 locus encodes a chloroplast-localized tRNA adenosine deaminase arginine (TADA) that is involved in chloroplast protein translation. The levels of flavonoids, which are naturally occurring auxin transport inhibitors in plants, were significantly higher in dig5 roots than in the wild type roots. Further investigation showed that flavonoid biosynthetic genes were upregulated in dig5. Introduction of the flavonoid biosynthetic mutation transparent testa 4 (tt4) into dig5 restored the lateral root growth of dig5. Our study uncovers an important role of DIG5/TADA in retrogradely controlling flavonoid biosynthesis and lateral root development. We suggest that the DIG5-related signaling pathways, triggered likely by drought-induced chlorophyll breakdown and leaf senescence, may potentially help the plants to adapt to drought stress through optimizing the root system architecture.     

钢筋混凝土结构抗震性能的设计谱曲线

基于性能的结构抗震设计正处于研究发展阶段,提出一种方法以适应当前需要。以我国现行的建筑抗震设计规范为基础,在设计中同时考虑地震作用以及结构侧移,得出结构等效单自由度体系的设计谱曲线,并由此求得结构在不同地震水准情况下的性能,检查其是否满足设计要求。结构设计完成后,可进行结构的弹塑性静力分析,全面复核结构性能。     

低耦合损耗的光电混合光纤旋转连接器

设计了一种光电混合光纤旋转连接器,能实现相对旋转的光信号在较大对准误差范围内低损耗连接.旋转状态下的自聚焦透镜准直光纤输出的光信号,并由PIN光电探测器将其转换为电信号,冉由激光器根据电信号再生出原始光信号继续在光纤通讯系统中传输.该光电混合光纤旋转连接器在离轴偏移量至520μm或对准倾斜角至0.5°时的附加耦合损耗为0.3 dB,而采用双自聚焦透镜的光纤旋转连接器要获得小于3 dB的插入损耗,其离轴偏移或倾斜角度必须小于100 μm和0.10°相比之下,本文设计的光纤旋转连接器能降低系统对机械加上及装配精度的要求,具有较高的实用价值.     

基于地质雷达技术的房屋周边缺陷探查

房屋周边的开裂、空洞、塌陷缺陷,影响着房屋的美观与使用。本文结合实际工程,对房屋周边的外露缺陷进行了检查记录,并运用地质雷达技术对房屋周边没有外露缺陷的位置进行了缺陷探查,亦探查出了下方存在明显的缺陷。该技术为快速普查房屋周边缺陷提供了一个好的解决方法。     

扶梯上侧板横撑液力成形仿真研究

目的 缩短上侧板横撑胀形件的开发周期,降低开发成本。方法 采用理论研究与仿真分析相结合的方法对胀形管件的壁厚分布及加载路径进行研究。首先,借助ABAQUS有限元软件,对简单管件两次液压成形过程进行仿真模拟,通过对比仿真结果与实验结果,验证仿真建模的正确性。其次,基于有限元软件对横撑管件液力成形、退火等过程进行仿真分析。最后,通过分析、总结获取合理的加载路径。结果 通过理论计算得到了预胀形所需的内压力值,为横撑管件预胀形仿真分析提供了参考。在预胀形阶段,当内压力<65 MPa时,由于内压力不足,管件无法成功胀形,当内压力>65 MPa时,管件中间胀形区域存在应力集中现象,不利于后续管件胀形,所以预胀形阶段的合理加载路径为常压65 MPa。在终胀形阶段,常压加载路径下的胀形结果不理想,而在多线性加载路径4下退火件及未退火件都能获得理想的胀形结果,因此,多线性加载路径4为终胀形的合理加载路径。结论 相较于常压加载,终胀形阶段采用多线性高压加载,管件成形效果更好;终胀形前进行退火处理,可以降低胀形管件的残余应力,壁厚分布也更加均匀。     

智能车辆横向控制研究

本文分析了智能车辆横向控制特性，说明了目前一些研究中的不足，并探讨了 模糊控制方法．仿真结果表明，该算法对纵向速度、轮胎侧偏刚度以及载荷等明显影响车辆 横向运动特性的三个关键因素具有良好的适应性能．     

TMEM106B Acts as a Modifier of Cognitive and Motor Functions in Amyotrophic Lateral Sclerosis

The transmembrane protein 106B (TMEM106B) gene is a susceptibility factor and disease modifier of frontotemporal dementia, but few studies have investigated its role in amyotrophic lateral sclerosis. The aim of this work was to assess the impact of the TMEM106B rs1990622 (A–major risk allele; G–minor allele) on phenotypic variability of 865 patients with amyotrophic lateral sclerosis. Demographic and clinical features were compared according to genotypes by additive, dominant, and recessive genetic models. Bulbar onset was overrepresented among carriers of the AA risk genotype, together with enhanced upper motor neuron involvement and poorer functional status in patients harboring at least one major risk allele (A). In a subset of 195 patients, we found that the homozygotes for the minor allele (GG) showed lower scores at the Edinburgh Cognitive and Behavioral Amyotrophic Lateral Sclerosis Screen, indicating a more severe cognitive impairment, mainly involving the amyotrophic lateral sclerosis-specific cognitive functions and memory. Moreover, lower motor neuron burden predominated among patients with at least one minor allele (G). Overall, we found that TMEM106B is a disease modifier of amyotrophic lateral sclerosis, whose phenotypic effects encompass both sites of onset and functional status (major risk allele), motor functions (both major risk and minor alleles), and cognition (minor allele).     

江南地区宋元时期传统木构铺作对结构整体抗连续倒塌性能的影响

为了研究江南地区宋元时期传统木构建筑的抗连续倒塌性能,选择典型实例,通过三维扫描测绘建立实例及对应无铺作大殿的有限元模型,并进行抽柱后结构的空间推覆分析,研究铺作在空间木构架连续倒塌时对结构传力路径及极限承载力的影响。结果表明:对于江南地区宋元传统木构建筑,当某根柱突然失效时,周围的梁、枋、槫、阑额等横向构件可以提供多个方向的拉结,防止结构进一步倒塌;铺作的存在对结构整体抗连续倒塌性能有明显提升,铺作之间的横向构件在倒塌时联合周围构件形成"组合桁架"共同受力,提供了有效传力路径和整体性拉结,使得局部柱失效后结构的极限承载力相对于无铺作结构提升约30%～50%;檐柱和角柱的失效更容易引起木构的连续性倒塌。     

一种基于二次误差测度的三维累进网格生成算法

研究了一类三维累进网格生成算法,在网格分辨率固定的前提下,以期获得较高质量的三维模型;基于二次误差模型,提出了基于累进网格生成的改进算法;引入了边界约束条件,提出了二阶邻域指标。实验证明,该算法输出的模型质量优于文献中的算法。