Filamentous bodies in human glomerulonephritis

Summary Filamentous bodies have been identified in the glomerular cells of human kidney biopsies. These structures have a close morphological resemblance to ciliary rootlets, although the cells of the glomerular tuft only occasionally bear cilia. Their significance could be, as for cilia, of a cellular disdifferentiation of a pathological cellular proliferation.     

光纤水听器PGC技术的反正切函数法研究

分析了基于PGC解调方案的DCM技术和反正切函数法(arctangent)的原理,并讨论了反正切函数法中载波信号幅度C的选择标准.与DCM技术相比,反正切函数法具有原理简单,受光功率波动的影响小,对光源的要求低等优点.仿真实验结果表明反正切函数法具有良好的解调效果和实际可行性.     

工程图学模型虚拟实验系统参数控制实现

工程图学模型虚拟实验系统是教学过程优化的一种崭新手段,可以有效地克服传统工程制图实验教学的缺陷.而系统参数控制解决了传统模型实验不能实现参数化控制、连续性变化的问题,突破了模型数量和学习时间的限制,实现了传统实验达不到的效果,提高了学生的图形认知能力和水平.     

The genome sequence of the plant pathogen Xylella fastidiosa. The Xylella fastidiosa Consortium of the Organization for Nucleotide Sequencing and Analysis

Xylella fastidiosa is a fastidious, xylem-limited bacterium that causes a range of economically important plant diseases. Here we report the complete genome sequence of X. fastidiosa clone 9a5c, which causes citrus variegated chlorosis--a serious disease of orange trees. The genome comprises a 52.7% GC-rich 2,679,305-base-pair (bp) circular chromosome and two plasmids of 51,158 bp and 1,285 bp. We can assign putative functions to 47% of the 2,904 predicted coding regions. Efficient metabolic functions are predicted, with sugars as the principal energy and carbon source, supporting existence in the nutrient-poor xylem sap. The mechanisms associated with pathogenicity and virulence involve toxins, antibiotics and ion sequestration systems, as well as bacterium-bacterium and bacterium-host interactions mediated by a range of proteins. Orthologues of some of these proteins have only been identified in animal and human pathogens; their presence in X. fastidiosa indicates that the molecular basis for bacterial pathogenicity is both conserved and independent of host. At least 83 genes are bacteriophage-derived and include virulence-associated genes from other bacteria, providing direct evidence of phage-mediated horizontal gene transfer.     

Origin of the cataclysmic Late Heavy Bombardment period of the terrestrial planets

The petrology record on the Moon suggests that a cataclysmic spike in the cratering rate occurred approximately 700 million years after the planets formed; this event is known as the Late Heavy Bombardment (LHB). Planetary formation theories cannot naturally account for an intense period of planetesimal bombardment so late in Solar System history. Several models have been proposed to explain a late impact spike, but none of them has been set within a self-consistent framework of Solar System evolution. Here we propose that the LHB was triggered by the rapid migration of the giant planets, which occurred after a long quiescent period. During this burst of migration, the planetesimal disk outside the orbits of the planets was destabilized, causing a sudden massive delivery of planetesimals to the inner Solar System. The asteroid belt was also strongly perturbed, with these objects supplying a significant fraction of the LHB impactors in accordance with recent geochemical evidence. Our model not only naturally explains the LHB, but also reproduces the observational constraints of the outer Solar System.     

支撑式冲击破岩掘进机垂向随机振动响应分析

为探究支撑式冲击破岩掘进机在随机载荷作用下垂直方向的振动响应特性,以某支撑式冲击破岩掘进机为例,根据多体动力学和拉格朗日法建立了垂向多体动力学模型,根据虚拟激励法构造虚拟载荷,得到相应的虚拟响应.分析确定了破碎锤随机冲击载荷,应用Matlab/Simulink进行仿真,得到该机破碎锤在最远位垂直底板冲击岩石时各部垂向振幅大小依次为破碎锤、支臂、机身,支臂最大扭转角为0.6401°,与实际情况相符.分析位移功率谱可知,破碎锤最大位移时的低频接近其固有频率,是导致该机振动的主要根源.     

Snake venoms: attractive antimicrobial proteinaceous compounds for therapeutic purposes

Gram-positive and -negative bacteria are dangerous pathogens that may cause human infection diseases, especially due to the increasingly high prevalence of antibiotic resistance, which is becoming one of the most alarming clinical problems. In the search for novel antimicrobial compounds, snake venoms represent a rich source for such compounds, which are produced by specialized glands in the snake’s jawbone. Several venom compounds have been used for antimicrobial effects. Among them are phospholipases A₂, which hydrolyze phospholipids and could act on bacterial cell surfaces. Moreover, metalloproteinases and l-amino acid oxidases, which represent important enzyme classes with antimicrobial properties, are investigated in this study. Finally, antimicrobial peptides from multiple classes are also found in snake venoms and will be mentioned. All these molecules have demonstrated an interesting alternative for controlling microorganisms that are resistant to conventional antibiotics, contributing in medicine due to their differential mechanisms of action and versatility. In this review, snake venom antimicrobial compounds will be focused on, including their enormous biotechnological applications for drug development.     

Morphology and larval development of Polydora cf. websteri (Polychaeta: Spionidae) in a tropical region of north-eastern Brazil

Polydora websteri belongs to a group of the Spionidae known as the Polydora complex, members of which are known for building tubes within the shells of mussels and for their ability to infest commercially valuable bivalves, which causes serious losses for malacoculture. P. websteri is a species subjected to increasing research due to the global scale at which these infestations occur. In this paper, we describe the larval development of P.cf. websteri associated with the oyster Crassostrea cf. brasiliana in a tropical region of north-east Brazil. The main structures of all stages of development were analysed and compared to other populations of P. websteri. Ovigerous capsules of P.cf. websteri were cultured in the laboratory and the larval stages were analysed until metamorphosis. Ovigerous capsules were present in all sampling intervals, indicating that this population exhibits continuous reproduction. Up to 21 capsules per tube were found, and the number of eggs per capsule varied from 20 to 40. All observed eggs developed into larvae. Larval development from egg to recruitment stage did not exceed 13 days. Metamorphosis occurred when larvae attained 17 chaetigers, at which stage important diagnostic characteristics were revealed, such as the spines on chaetiger 5. The developmental stages of P.cf. websteri larvae, and the morphological features found at each stage, are in accordance with what has been recorded for temperate populations. In our study, the planktonic stage was found to be of shorter duration than elsewhere, which might be associated with the higher temperatures at which larvae were cultured compared to previous studies.     

木醋液除臭工艺研究

分析了小兴安岭松木枝杈及加工废料干馏木醋液,研究了不同条件下木醋液对禽舍的除臭效果。结果表明,木醋液有机成分中乙酸含量最高,可与氨气作用后达到除臭效果;粗木醋液比蒸馏木醋液的乙酸含量略高;随着木醋液用量的增加,除臭效果提高;除臭效果在16 h前随作用时间延长而提高,16 h后趋于稳定;表面活性剂对除臭效果正面影响很小。实际应用时若考虑降低成本,选用质量分数为60 %(相对于污泥)的粗木醋液,作用于鸡舍污泥16 h后除臭效果最佳。