液压缸驱动剪叉机构的运动学及动力学分析

对液压缸驱动的剪叉机构进行了运动学及动力学分析，推导出液压缸活塞运动速度与剪叉机构运动速度的关系式及活塞推力与剪叉机构荷重的关系式，并给出了实例及计算结果。     

Homozygous HOXA1 mutations disrupt human brainstem, inner ear, cardiovascular and cognitive development

We identified homozygous truncating mutations in HOXA1 in three genetically isolated human populations. The resulting phenotype includes horizontal gaze abnormalities, deafness, facial weakness, hypoventilation, vascular malformations of the internal carotid arteries and cardiac outflow tract, mental retardation and autism spectrum disorder. This is the first report to our knowledge of viable homozygous truncating mutations in any human HOX gene and of a mendelian disorder resulting from mutations in a human HOX gene critical for development of the central nervous system.     

Mechanical properties and microstructure of composites produced by recycling metal chips

In this study, the processing and mechanical properties of porous metal matrix composites (MMCs) composed of spheroidal cast iron chips (GGG40) and bronze chips (CuSn10) and formed by hot isostatic pressing were investigated. Bronze chips (CuSn10) were used as a matrix component, and spheroidal cast iron (GGG40) chips were used as a reinforcement component. The MMCs were produced with different CuSn10 contents (90wt%, 80wt%, 70wt%, and 60wt%). The hot isostatic pressing process was performed under three different pressures and temperatures. The produced MMCs were characterized using density tests, Brinell hardness tests, and compression tests. In addition, the consolidation mechanism was investigated by X-ray diffraction (XRD) analysis and scanning electron microscopy. The test results were compared with those for bulk CuSn10 and bulk GGG40. Mechanical tests results revealed that the metallic chips can be recycled by using hot pressing and that the mechanical properties of the produced MMCs were similar to those of bulk CuSn10. XRD and microscopy studies showed that no intermetallic compounds formed between the metallic chips. The results showed that the CuSn10 and GGG40 chips were consolidated by mechanical interlocking.     

新疆4个绵羊群体MHC-DRB1基因外显子2多态性的遗传分析

采用PCR-RFLP的方法研究了哈萨克羊、多浪羊、中国美利奴羊(新疆军垦型)及哈萨克羊与中国美利奴羊(新疆军垦型)杂交一代的MHC-DRB1基因外显子2遗传多态性。结果显示,4个绵羊群体的MHC-DRB1基因外显子2表现出丰富的多态性,共检测到28种基因型和14个等位基因,其在4个绵羊群体间的分布存在不一致。对4个群体的遗传参数检测结果显示,MHC-DRB1基因外显子2的基因杂合度较大,遗传变异程度较高。根据MHC-DRB1基因外显子2在5个酶切位点的等位基因频率对4个绵羊群体进行了聚类分析,结果反映了4个群体间就MHC多态性建立的遗传关系,并初步探讨了4个群体间抗病性的相互关系。     

Heterozygous mutations of the kinesin KIF21A in congenital fibrosis of the extraocular muscles type 1 (CFEOM1)

Congenital fibrosis of the extraocular muscles type 1 (CFEOM1; OMIM #135700) is an autosomal dominant strabismus disorder associated with defects of the oculomotor nerve. We show that individuals with CFEOM1 harbor heterozygous missense mutations in a kinesin motor protein encoded by KIF21A. We identified six different mutations in 44 of 45 probands. The primary mutational hotspots are in the stalk domain, highlighting an important new role for KIF21A and its stalk in the formation of the oculomotor axis.