Natural history and evolutionary principles of gene duplication in fungi

Gene duplication and loss is a powerful source of functional innovation. However, the general principles that govern this process are still largely unknown. With the growing number of sequenced genomes, it is now possible to examine these events in a comprehensive and unbiased manner. Here, we develop a procedure that resolves the evolutionary history of all genes in a large group of species. We apply our procedure to seventeen fungal genomes to create a genome-wide catalogue of gene trees that determine precise orthology and paralogy relations across these species. We show that gene duplication and loss is highly constrained by the functional properties and interacting partners of genes. In particular, stress-related genes exhibit many duplications and losses, whereas growth-related genes show selection against such changes. Whole-genome duplication circumvents this constraint and relaxes the dichotomy, resulting in an expanded functional scope of gene duplication. By characterizing the functional fate of duplicate genes we show that duplicated genes rarely diverge with respect to biochemical function, but typically diverge with respect to regulatory control. Surprisingly, paralogous modules of genes rarely arise, even after whole-genome duplication. Rather, gene duplication may drive the modularization of functional networks through specialization, thereby disentangling cellular systems.     

影响铸造涂料工艺性能的因素分析

通过正交实验研究，测试了铸造涂料的碾压工艺、原材料以及原材料的处理工艺对涂料的悬浮性、表面强度、发气量等主要工艺性能的影响。结果表明：当选用轮碾机制作铸造涂料时，碾压时间达到１．５小时即可满足工艺性能的要求；涂料中无论是粘结剂还是悬浮剂的增加均会大幅度提高涂料的表面强度和悬浮性。     

一种基于CMAC网络的自学习控制器

通过分析了ＣＭＡＣ神经网络的学习机制和连续搅拌反应釜的结构，提出了一种自动选择学习率的ＣＭＡＣ自学习控制方法。给出了自学习控制器的结构和算法，并以连续搅拌反应釜模型为对象进行了仿真研究，这种网络每次学习少量参数，算法简单，仿真结果表明所提出的控制器优于传统的ＰＩＤ控制器。     

Sn—Pb／Cu润湿性测试分析研究

介绍了利用图象处理技术研究了Ｓｎ－Ｐｂ合金钱民铜润湿性的方法，提出了联机的图象特征提出算法和润湿参数求取算法，给出了Ｓｎ－Ｐｂ／Ｃｕ润湿特性在直流电影响下测试分析结果。     

基于加权全局时频特征的易混淆词识别

针对易混淆词特征差异小,分类决策困难的特点,提出了一种新的语音识别特征。该特征可以根据待识单词的发音特点,通过选用合适的基函数及加权处理,突出混淆词特征之间的差异性;     

我国淡水水产品加工业的现状与前景展望

通过分析我国水产品养殖业和加工业的现状、存在问题以及人们将来对淡水水产品深精加工食品的需求趋势,指出我国应该大力发展淡水鱼的深精加工技术,生产淡水鱼深精加工方便食品,以满足人们对营养、方便、卫生食品的需求。     

生物驻极体极化弛豫特性的热刺激电流分析

采用热刺激电流的方法,以猪的肩胛骨为例,对生物体的驻极效应进行了研究,并由此对生物驻极体的极化弛豫特性作了分析．实验表明,复杂的有机生命体中存在着显著的电荷储存效应,产生这一效应的基本原因在于生物体胶原纤维和基质细胞中的结合水及生物体内少量可动载流子,从单一频率弛豫进行计算所得的ＴＳＤＣ谱图与测量结果基本一致,说明其弛豫过程主要对应于单一频率的水分子的极化弛豫．     

Nitrogen transfer in the arbuscular mycorrhizal symbiosis

Most land plants are symbiotic with arbuscular mycorrhizal fungi (AMF), which take up mineral nutrients from the soil and exchange them with plants for photosynthetically fixed carbon. This exchange is a significant factor in global nutrient cycles as well as in the ecology, evolution and physiology of plants. Despite its importance as a nutrient, very little is known about how AMF take up nitrogen and transfer it to their host plants. Here we report the results of stable isotope labelling experiments showing that inorganic nitrogen taken up by the fungus outside the roots is incorporated into amino acids, translocated from the extraradical to the intraradical mycelium as arginine, but transferred to the plant without carbon. Consistent with this mechanism, the genes of primary nitrogen assimilation are preferentially expressed in the extraradical tissues, whereas genes associated with arginine breakdown are more highly expressed in the intraradical mycelium. Strong changes in the expression of these genes in response to nitrogen availability and form also support the operation of this novel metabolic pathway in the arbuscular mycorrhizal symbiosis.     

SS3B电力机车新制构架焊接变形的控制

分析了SS3B新制构架及侧梁在焊接过程中易产生的各种变形。针对焊接中的变形问题，通过对焊接材料参数的到定，制定了SS3B新制构架及侧梁的焊接工艺，使焊接变形得到有效控制，保证了新制构架的产品质量。