3-D Design and Numerical Simulation of Two-Phase Flow in the Laser Rapid Prototyping Coaxial Powder Delivery System

The metal powder direct and rapid prototyping technology is one of the most developing methods in the laser rapid prototyping technique. The coaxial powder delivery system is the key technique. The purpose of this paper is to introduce a new type of coaxial powder delivery system and simulate the metal powder and shield gas flow in the powder nozzle. 2-D and 3-D model of the new coaxial powder delivery system are established. Then gas-solid two-phase flow model and the k-? turbulent model are selected to simulate the flow of metal powder in powder nozzle. The Euler-Lagrange method is used in the simulating computation. The results show that the new coaxial powder delivery system has stable performance, uniform powder flux, high cooling efficiency, and long useful life.     

玻璃微球敏化乳化炸药爆速特性

建立了乳化炸药实验室制备工艺，并自制了玻璃微球敏化的乳化炸药试样，通过对试样的爆速测试，研究了乳化炸药爆速与其密度及玻璃微球含量等因素的关系，分析了这种工业炸药爆速的特点，结果表明，这种乳化炸药的爆速随其密度的增大而增大到最大值后逐渐降低，直到被压死。     

基于AHP的秀山县生物资源可持续发展力评价

为了实现秀山县生物资源的可持续性发展,构建了秀山县生物资源的经济发展系统、社会发展系统、生物资源基础系统、可持续发展实施系统4项准则层和人均GDP等21项指标的评价体系。运用AHP层次分析方法,两两比较得出判断矩阵,进而算出各项指标权重,通过多目标加权函数方法,最终得出秀山县可持续发展力得分为6.79,处于可持续发展力一般的阶段。通过评价结果,分析了秀山县生物资源可持续发展的主要问题,提出了生物资源可持续发展的建议与对策。     

带非线性边界条件热方程组正解的爆破速率估计

利用最大最小值原理和上下解的方法,研究了一类既有非线性反应项又有非线性边界条件的热方程组正解爆破速率的估计,得到了估计的上下界.     

Mesoangioblast stem cells ameliorate muscle function in dystrophic dogs

Duchenne muscular dystrophy remains an untreatable genetic disease that severely limits motility and life expectancy in affected children. The only animal model specifically reproducing the alterations in the dystrophin gene and the full spectrum of human pathology is the golden retriever dog model. Affected animals present a single mutation in intron 6, resulting in complete absence of the dystrophin protein, and early and severe muscle degeneration with nearly complete loss of motility and walking ability. Death usually occurs at about 1 year of age as a result of failure of respiratory muscles. Here we report that intra-arterial delivery of wild-type canine mesoangioblasts (vessel-associated stem cells) results in an extensive recovery of dystrophin expression, normal muscle morphology and function (confirmed by measurement of contraction force on single fibres). The outcome is a remarkable clinical amelioration and preservation of active motility. These data qualify mesoangioblasts as candidates for future stem cell therapy for Duchenne patients.     

Infantile-onset symptomatic epilepsy syndrome caused by a homozygous loss-of-function mutation of GM3 synthase

We identified an autosomal recessive infantile-onset symptomatic epilepsy syndrome associated with developmental stagnation and blindness. Assuming a founder effect in a large Old Order Amish pedigree, we carried out a genome-wide screen for linkage and identified a single region of homozygosity on chromosome 2p12-p11.2 spanning 5.1 cM (maximum lod score of 6.84). We sequenced genes in the region and identified a nonsense mutation in SIAT9, which is predicted to result in the premature termination of the GM3 synthase enzyme (also called lactosylceramide alpha-2,3 sialyltransferase). GM3 synthase is a member of the sialyltransferase family and catalyzes the initial step in the biosynthesis of most complex gangliosides from lactosylceramide. Biochemical analysis of plasma glycosphingolipids confirmed that affected individuals lack GM3 synthase activity, as marked by a complete lack of GM3 ganglioside and its biosynthetic derivatives and an increase in lactosylceramide and its alternative derivatives. Although the relationship between defects in ganglioside catabolism and a range of lysosomal storage diseases is well documented, this is the first report, to our knowledge, of a disruption of ganglioside biosynthesis associated with human disease.