Influence of impact velocity and impact attack angle of bullets on damage of human tissue surrogate -- ballistic gelatin.

PURPOSE: Terminal performance of a bullet in human body is critical for the treatment of gunshot injury and optimization of bullet design. The effects of the impact velocity (v0) and the impact attack angle (δ0) of the bullet on its terminal performance was investigated, using a new evaluation method (called expansion method) based on the expansion of cracks and the permanent cavity wall in ballistic gelatin. METHODS: Ballistic gelatin was used to simulate human body. The 7.62 mm × 39 mm rifle bullets with different v0 (600-760 m/s) and δ0 (0°-6°) were fired into the gelatin blocks. The gelatin block was cut into slices of about 20 mm thickness. The cracks and the permanent cavity on each slice were obtained manually. The damaged gelatin was determined using two methods: expanding the permanent cavity but ignoring the cracks, and expanding both the permanent cavity and the cracks. The relations between the damaged gelatin and v0 and δ0 were obtained using linear fitting method. RESULTS: According to the distribution of the damaged gelatin along the penetration depth, the damaged gelatin block could be divided into two parts: the less damaged part and the severely damaged part. The length of the less damaged part depends mostly on δ0; while the average damaged area of this part depends on both δ0 as well as v0. The cracks contributed significantly to the total volume of damaged gelatin, particularly when the expansion was larger than 1.9 mm. The total damaged gelatin increases with v0, δ0 and the expansion extent. The average length of equivalent cracks grew with v0 and δ0 when considering the cracks, and decreased with v0 when ignoring the cracks. CONCLUSION: The expansion method is suitable to investigate the influence of different factors of bullets on their terminal performance. The characteristics of the damaged gelatin have a linear relationship with the initial attack angle (δ0) and the initial velocity (v0) of the bullet.

[Fire needling on dysphagia due to pseudobulbar palsy after stroke: a randomized controlled trial].

OBJECTIVE: To observe the clinical effect of fire needling on dysphagia due to pseudobulbar paralysis after stroke and to compare the difference in clinical effect between fire needling and swallowing function rehabilitation training. METHODS: A total of 76 patients with dysphagia due to pseudobulbar paralysis after stroke were randomly divided into an observation group and a control group, 38 cases in each group (1 case dropped out in the control group). The both groups were based on conventional western medication treatment. Fire needle pricking was exerted at Lianquan (CV 23), Fengchi (GB 20), Wangu (GB 12), Shuigou (GV 26), Neiguan (PC 6) and Zusanli (ST 36) without needle retaining every other day in the observation group. The control group was treated with the swallowing function rehabilitation training. In both groups, treatment for 2 weeks was as one course and 2 courses of treatment with 2-day interval were required. After treatment, swallowing scores of Fujishima Ichiro and swallow quality of life questionnaire (SWAL-QOL) scores were observed in both groups, and the clinical effect was compared. Follow-up of swallowing scores of Fujishima Ichiro in 4 weeks after treatment was completed to evaluate the clinical effect. RESULTS: The clinical effective rates after treatment and follow-up were 92.1% (35/38) and 94.7% (36/38) in the observation group, higher than 75.7% (28/37) and 83.8% (31/37) in the control group (P<0.05). After treatment, the swallowing scores of Fujishima Ichiro and SWAL-QOL scores were increased in the two groups (P<0.05), and those in the observation group were higher than the control group (P<0.05). The swallowing scores of Fujishima Ichiro were increased during follow-up in the two groups (P<0.05). CONCLUSION: Fire needling has a better effect than conventional rehabilitation training in the treatment of dysphagia due to pseudobulbar paralysis after stroke, which can obviously improve the swallowing function and quality of life in patients with dysphagia.