Study on the Low-Velocity Impact Response and Damage Mechanisms of Thermoplastic Composites.

A comparative experimental and numerical study of the impact behaviour of carbon-fiber-reinforced thermoplastic (TP) and thermoset (TS) composites has been carried out. On the one hand, low velocity impact (LVI) tests were performed on TP and TS composites with different lay-up sequences at different energy levels, and the damage modes and microscopic damage mechanisms after impact were investigated using macroscale inspection, C-scan inspection, and X-ray-computed tomography. The comparative results show that the initial damage valve force under LVI depends not only on the material, but also on the layup sequence. The initial valve force of the P2 soft layer with lower stiffness is about 11% lower than that of the P1 quasi-isotropic layer under the same material, while the initial valve force of thermoplastic composites is about 28% lower than that of thermoset composites under the same stacking order. Under the same stacking order and impact energy level, the damage area and depth of TP composites are smaller than those of TS composites; while under the same material and impact energy level, the indentation depth of P2 plies is greater than that of P1 plies, and the damage area of P2 plies is smaller than that of P1 plies, but the change of thermoplastic composites is not as obvious as that of thermoset composites. This indicates that TP composites have a higher initial damage threshold energy and impact resistance at the same lay-up order, while increasing the lay-up ratio of the same material by 45° improves the impact resistance of the structure. In addition, a damage model based on continuum damage mechanics (CDM) was developed to predict different damage modes of thermoplastic composites during low velocity impact, and the analytical results were compared with the experimental results. At an impact energy of 4.45 J/mm, the error of the initial damage valve force is 5.26% and the error of the maximum impact force is 4.36%. The simulated impact energy and impact velocity curves agree with the experimental results, indicating that the finite element model has good reliability.

[Clinical phenotype and genotype analysis of the family with the Usher syndrome].

OBJECTIVE: To detect potential variants in a family affected with Usher syndrome type I, and analyze its genotype-phenotype correlation. METHODS: Clinical data of the family was collected. Potential variants in the proband were detected by high-throughput sequencing. Suspected variants were verified by Sanger sequencing. RESULTS: The proband developed night blindness at 10 year old, in addition with bilateral cataract and retinal degeneration. Hearing loss occurred along with increase of age. High-throughput sequencing and Sanger sequencing revealed that she has carried compound heterozygous variants of the MYO7A gene, namely c.2694+2T>G and c.6028G>A. Her sister carried the same variants with similar clinical phenotypes. Her daughter was heterozygous for the c.6028G>A variant but was phenotypically normal. CONCLUSION: The clinical features and genetic variants were delineated in this family with Usher syndrome type I. The results have enriched the phenotype and genotype data of the disease and provided a basis for genetic counseling.

Efficacy of Xuebijing for coagulopathy in patients with sepsis.

OBJECTIVES: To provide evidence of the clinical efficacy of Xuebijing (XBJ) on blood coagulation in patients with sepsis. METHODS: We conducted this meta-analysis in The People's Hospital of Liaoning Province, Shenyang, China between December 2013 and May 2014. We searched a number of databases for relevant randomized controlled trials (RCTs) published before December 2013 using the keywords 'Xuebijing', 'coagulation' and 'sepsis'. Statistical analysis was performed with Review Manager 5.2 from the Cochrane Collaboration. RESULTS: Fourteen RCTs involving 867 patients were included. Compared with placebo, XBJ injection significantly improved platelets (mean differences [MD] = 42.14, 95% confidence interval [CI]: 22.42 - 61.86, p<0.00001), shortened the activated partial thromboplastin time (MD = -4.81, 95% CI: -7.86 - [-1.76], p=0.002), shortened the prothrombin time (MD = -2.33, 95% CI: -4.15 - [-0.51], p=0.01), and shortened the thrombin time (MD = -2.05, 95% CI: -3.52 - [-0.58], p=0.006). However, no significant difference was found between the XBJ injection and the placebo group for fibrinogen (MD = 0.21, 95% CI: -0.38 - 0.81, p=0.48). CONCLUSION: Xuebijing injection may improve coagulopathy in patients with sepsis. High-quality and large sample clinical trials are needed for confirmation.