Experimental and Numerical Study on the Mechanical Behavior of Composite Steel Structure under Explosion Load

Most engineering structures are composed of basic components such as plates, shells, and beams, and their dynamic characteristics under explosion load determine the impact resistance of the structure. In this paper, a three-dimensional composite steel structure was designed using a beam, plate, and other basic elements to study its mechanical behavior under explosion load. Subsequently, experiments on the composite steel structure under explosion load were carried out to study its mechanical behavior, and the failure mode and deformation data of the composite steel structure were obtained, which provided important experimental data regarding the dynamic response and mechanical behavior of the composite steel structure under explosion load. Then, we independently developed a parallel program with the coupled calculation method to solve the numerical simulation of the dynamic response and failure process of the composite steel structure under explosion load. This program adopts the Euler method as a whole, and Lagrange particles are used for materials that need to be accurately tracked. The numerical calculation results are in good agreement with the experimental data, indicating that the developed parallel program can effectively deal with the large deformation problems of multi-medium materials and the numerical simulation of the complex engineering structure failures subjected to the strong impact load.     

水下爆炸致水面泅渡战位比格犬脑和肺的损伤特点

目的 研究水下爆炸引起水面泅渡战位比格犬脑和肺的损伤情况.方法 20只健康比格犬随机分为4个实验组(距爆源5、8、11和15 m)和1个对照组(n=4).利用1 kg 2,4,6-三硝基甲苯(TNT)裸药在水下2 m实施爆炸对水中漂浮比格犬进行致伤,采用水下及颅内压力传感器和高速摄像机记录爆炸致伤的过程.爆炸后3 h内对存活的比格犬行头部和胸部CT检查及头部MRI检查.爆炸后24 h取脑和肺标本,观察颅脑和胸、肺大体损伤情况,并通过H-E染色和TUNEL染色观察脑和肺组织病理学变化及细胞凋亡情况.结果 压力传感器和高速摄像机观察到水下爆炸的致伤过程包括冲击波作用和气泡作用2个阶段.5 m、8 m、11 m和15 m组比格犬分别死亡4、3、1、0只.头部CT和MRI检查示实验组比格犬脑组织没有明显损伤,胸部CT检查示有肺内出血、气胸、血胸或胸腔积液等表现.H-E染色结果示实验组比格犬脑组织无明显变化,而肺组织肺泡破裂,肺泡腔内有大量红细胞,肺间质内有大量炎症细胞浸润.TUNEL染色仅见海马区少量细胞呈阳性表现,而肺组织肺泡上皮细胞和间质细胞呈现广泛的凋亡坏死趋势.结论 水下爆炸引起水面泅渡战位比格犬的损伤主要为肺爆震伤,脑组织损伤相对轻微.     

爆炸冲击波性腹部损伤的研究进展

在近年来恐怖袭击事件中,爆炸冲击波性腹部损伤是无辜民众遭受的一种严重且隐匿的创伤,但其确切的致伤机制及有效的诊断方案仍不确定。本文针对冲击波性腹部损伤可能的致伤机制、临床表现及诊断方案等进行综述,在查阅国内外近年来关于腹部损伤相关文献的基础上进行提炼总结。腹部的受伤程度与冲击波超压值和超压作用时间紧密相关,且小肠是最易受伤的脏器。针对腹部损伤隐匿性强的特点,影像学检查结合传统的临床观察被应用于腹部伤情的诊断。爆炸现场,对无明显外伤但有腹膜炎临床表现的伤员,均应考虑到发生冲击伤的可能性,以免漏诊贻误病情。     

水下内镜切除术在消化道肿瘤治疗中的应用 （附452例综合分析）*

目的探讨水下内镜切除术在治疗消化道肿瘤中的疗效及安全性。方法通过美国国立医学图书馆搜索引擎PubMed,分别以"underwater endoscopic mucosal resection","underwater endoscopic submucosal dissection","underwater peroral endoscopic myotomy"为关键词,检索出相关文献,汇总病例并进行分析。结果共检索出40篇相关文献,纳入452例病例,其中水下内镜下黏膜切除术(UEMR)413例,水下内镜黏膜下剥离术(UESD)37例,水下经口内镜下肌切开术(UPOEM)2例。413例UEMR患者一共有468个病灶,切除成功率为98.5%,其中整块切除率达61.1%,整块切除者的R0切除率为94.3%;37例UESD患者共有39个病灶,所有病灶均经UESD完整剥离;2例UPOEM患者成功行水下黏膜下隧道建立及肌切开。全组术后并发症较低,以出血多见,其他包括穿孔、十二指肠腔狭窄、低钠血症、吸入性肺炎和自限性息肉切除术后综合征。结论水下内镜切除技术是一项较为安全有效的治疗手段,易于掌握且操作方便。今后仍需要更多的临床研究以及长期随访资料,以明确水下内镜切除技术与常规内镜下黏膜切除术(EMR)或内镜黏膜下剥离术(ESD)相比的优势及适应证,便于临床应用及推广。     

Sucker with a fat lip: The soft tissues underlying the viscoelastic grip of remora adhesion

Remoras are fishes that attach to a broad range of hosts using an adhesive disc on their head that is derived from dorsal fin elements. Research on the adhesive mechanism of remoras has focused primarily on the skeletal components of the disc and their contribution to generating suction and friction. However, the soft tissues of the disc, such as the soft lip surrounding the bony disc and the muscles that control the bony lamellae, have been largely ignored. To understand the sealing mechanism of the disc, it is imperative to understand the tissue morphology and material properties of the soft lip. Here, we show that the soft lip surrounding the remora disc is comprised of discrete multilayered collagen, fat, and elastic tissues which we hypothesize to have specific roles in the viscoelastic sealing mechanism of the remora disc. The central, heavily vascularized fat and collagen layer are infiltrated by strands of elastic tissue and surrounded by crossed-fiber collagen. A newly described jubilee muscle underneath the adhesive disc provides a mechanism for stopping venous return from the disc lip, thereby allowing it to become engorged and create a pressurized fit to the attachment substrate. Thus, the remora lip acts as a vascular hydrostat.