Effects of Blast Wave-induced Biomechanical Changes on Lung Injury in Rats

Objective To observe the dynamic impacts of shock waves on the severity of lung injury in rats with different injury distances.Methods Simulate open-field shock waves;detect the biomechanical effects of explosion sources at distances of 40,44,and 48 cm from rats;and examine the changes in the gross anatomy of the lungs,lung wet/dry weight ratio,hemoglobin concentration,blood gas analysis,and pathology.Results Biomechanical parameters such as the overpressure peak and impulse were gradually attenuated with an increase in the injury distance.The lung tissue hemorrhage,edema,oxygenation index,and pathology changed more significantly for the 40 cm group than for the 44 and 48 cm groups.The overpressure peak and impulse were significantly higher for the 40 cm group than for the 44 and 48 cm groups(P<0.05 or P<0.01).The animal mortality was significantly higher for the 40 cm group than for the other two groups(41.2%vs.17.8%and 10.0%,P<0.05).The healing time of injured lung tissues for the 40 cm group was longer than those for the 44 and 48 cm groups.Conclusions The effects of simulated open-field shock waves on the severity of lung injuries in rats were correlated with the injury distances,the peak overpressure,and the overpressure impulse.

Identification of overlay differentially expressed genes in both rats and goats with blast lung injury through comparative transcriptomics

Purpose:To identify the potential target genes of blast lung injury(BLI)for the diagnosis and treatment.Methods:This is an experimental study.The BLI models in rats and goats were established by conducting a fuel-air explosive power test in an unobstructed environment,which was subsequently validated through hematoxylin-eosin staining.Transcriptome sequencing was performed on lung tissues from both goats and rats.Differentially expressed genes were identified using the criteria ofq≤0.05 and|log2 fold change|≥1.Following that,enrichment analyses were conducted for gene ontology and the Kyoto Encyclopedia of Genes and Genomes pathways.The potential target genes were further confirmed through quantitative real-time polymerase chain reaction and enzyme linked immunosorbent assay.Results:Observations through microscopy unveiled the presence of reddish edema fluid,erythrocytes,and instances of focal or patchy bleeding within the alveolar cavity.Transcriptome sequencing analysis identified a total of 83 differentially expressed genes in both rats and goats.Notably,49 genes exhibited a consistent expression pattern,with 38 genes displaying up-regulation and 11 genes demonstrating down-regulation.Enrichment analysis highlighted the potential involvement of the interleukin-17 signaling pathway and vascular smooth muscle contraction pathway in the underlying mechanism of BLI.Furthermore,the experimental findings in both goats and rats demonstrated a strong association between BLI and several key genes,including anterior gradient 2,ankyrin repeat domain 65,bactericidal/permeability-increasing fold containing family A member 1,bactericidal/permeability-increasing fold containing family B member 1,and keratin 4,which exhibited up-regulation.Conclusions:Anterior gradient 2,ankyrin repeat domain 65,bactericidal/permeability-increasing fold containing family A member 1,bactericidal/permeability-increasing fold containing family B member 1,and keratin 4 hold potential as target genes for the prognosis,diagnosis,and treatment of BLI.

Biomechanical modeling for the response of human thorax to blast waves

A simplified finite element model of a human thorax had been developed for probing into the mechani- cal response in simple and complex blast environments. The human thorax model was first created by CT images with blast loading applied via a coupled arbitrary Lagrangian- Eulerian method, allowing for a variety of loads to be considered. The goal is to analyze the maximum stress distri- butions of lung tissue and peak inward thorax wall velocity and to know the possible regions and levels of lung injury. In parallel, a mathematical model has been modified from the Lobdell model to investigate the detailed percentage of lung injury at each level. The blast loadings around the human tho- rax were obtained from the finite element model, and were then applied in the mathematical model as the boundary con- ditions to predict the normalized work of the human thorax lung. The present results are found in agreement with the modified Bowen curves and the results predicted by Axels- son＇s model.

Nanometer ultrastructural brain damage following low intensity primary blast wave exposure

Blast-induced mild traumatic brain injury（m TBI） is of particular concern among military personnel due to exposure to blast energy during military training and combat.The impact of primary low-intensity blast mediated pathophysiology upon later neurobehavioral disorders has been controversial.Developing a military preclinical blast model to simulate the pathophysiology of human blast injury is an important first step.This article provides an overview of primary blast effects and perspectives of our recent studies demonstrating ultrastructural changes in the brain and behavioral disorders resulting from open-field blast exposures up to 46.6 k Pa using a murine model.The model is scalable and permits exposure to varying magnitudes of primary blast injuries by placing animals at different distances from the blast center or by changing the amount of C4 charge.We here review the implications and future applications and directions of using this animal model to uncover the underlying mechanisms related to primary blast injury.Overall,these studies offer the prospect of enhanced understanding of the pathogenesis of primary low-intensity blast-induced TBI and insights for prevention,diagnosis and treatment of blast induced TBI,particularly m TBI/concussion related to current combat exposures.

Effects of orientation and distance of goats on blast lung injury characteristics on a plateau above 4500-meter

Purpose:High explosives are used to produce blast waves to study their biological effects.The lungs are considered as the critical target organ in blast-effect studies.The degree of lung hemorrhaging is related to both the explosive power and the increased lung weight.We studied the characteristics of the biological effects from an air explosion of a thermobaric bomb in a high-altitude environment and the lethality and lung injury severity of goats in different orientations and distances.Methods:Goats were placed at 2.5,3,4,and 5 m from the explosion center and exposed them to an air blast at an altitude of 4700-meter.A group of them standing oriented to the right side and the other group seated facing the explosion center vertically.The lung injuries were quantified according to the percentage of surface area contused,and using the pathologic severity scale of lung blast injury(PSSLBI)to score the 4 injury categories(slight,moderate,serious and severe)as 1,2,3,and 4,respectively.The lung coefficient(lung weight[g]/body weight[kg])was the indicator of pulmonary edema and was related to lung injury severity.Blast overpressure data were collected using blast test devices placed at matching locations to represent loadings to goats.All statistical analyses were performed using SPSS,version 26.0,statistical software(SPSS,Inc.,Chicago,IL,USA).Results:In total,127 goats were involved in this study.Right-side-standing goats had a significantly higher mortality rate than those seated vertical-facing(p<0.05).At the 2.5 m distance,the goat mortality was nearly 100%,whereas at 5 m,all the goats survived.Lung injuries of the right-side-standing goats were 1-2 grades more serious than those of seated goats at the same distances,the scores of PSSLBI were significantly higher than the seated vertical-facing goats(p<0.05).The lung coefficient of the right-side-standing goats were significantly higher than those of seated vertical-facing(p<0.05).Mortality,PSSLBI,and the lung coefficient results indicated that the right-side-standing goats experienced severer injuries than the seated vertical-facing goats,and the injuries were lessened as the distance increased.The blast overpressure was consistent with these results.Conclusion:The main killing factors of the thermobaric bomb in the high-altitude environment were blast overpressure,blast wind propulsions and burn.The orientation and distances of the goats significantly affected the blast injury severity.These results may provide a research basis for diagnosing,treating and protecting against injuries from thermobaric explosions.

Global gene expression profiling of blast lung injury of goats exposed to shock wave

Purpose:Blast lung injury(BLI)is the most common damage resulted from explosion-derived shock wave in military,terrorism and industrial accidents.However,the molecular mechanisms underlying BLI induced by shock wave are still unclear.Methods:In this study,a goat BLI model was established by a fuel air explosive power.The key genes involved in were identified.The goats of the experimental group were fixed on the edge of the explosion cloud,while the goats of the control group were 3 km far away from the explosive environment.After successful modeling for 24 h,all the goats were sacrificed and the lung tissue was harvested for histopathological observation and RNA sequencing.Gene ontology(GO)and kyoto encyclopedia of genes and genomes(KEGG)analysis were performed to identify the main enriched biological functions of differentially expressed genes(DEGs).Quantitative real-time polymerase chain reaction(qRT-PCR)was used to verify the consistency of gene expression.Results:Of the sampled goat lungs,895 genes were identified to be significantly differentially expressed,and they were involved in 52 significantly enriched GO categories.KEGG analysis revealed that DEGs were highly enriched in 26 pathways,such as cytokine-cytokine receptor interaction,antifolate resistance,arachidonic acid metabolism,amoebiasis and bile secretion,JAK-STAT,and IL-17 signaling pathway.Furthermore,15 key DEGs involved in the biological processes of BLI were confirmed by qRTPCR,and the results were consistent with RNA sequencing.Conclusion:Gene expression profiling provide a better understanding of the molecular mechanisms of BLI,which will help to set strategy for treating lung injury and preventing secondary lung injury induced by shock wave.

Development of an experimental method for well-controlled blast induced traumatic limb fracture in rats

Heterotopic ossification(HO)is a consequence of traumatic bone and tissue damage,which occurs in 65%of military casualties with blast-associated amputations.However,the mechanisms behind blast-induced HO remain unclear.Animal models are used to study blast-induced HO,but developing such models is challenging,particularly in how to use a pure blast wave(primary blast)to induce limb fracture that then requires an amputation.Several studies,including our recent study,have developed platforms to induce limb fractures in rats with blast loading or a mixture of blast and impact loading.However,these models are limited by the survivability of the animal and repeatability of the model.In this study,we developed an improved platform,aiming to improve the animal's survivability and injury repeatability as well as focusing on primary blast only.The platform exposed only one limb of the rat to a blast wave while providing proper protection to the rest of the rat's body.We obtained very consistent fracture outcome in the tibia(location and pattern)in cadaveric rats with a large range of size and weight.Importantly,the rats did not obviously move during the test,where movement is a potential cause of uncontrolled injury.We further conducted parametric studies by varying the features of the design of the platform.These factors,such as how the limb is fixed and how the cavity through which the limb is placed is sealed,significantly affect the resulting injury.This platform and test setups enable well-controlled limb fracture induced directly by pure blast wave,which is the fundamental step towards a complete in vivo animal model for blast-induced HO induced by primary blast alone,excluding secondary and tertiary blast injury.In addition,the platform design and the findings presented here,particularly regarding the proper protection of the animal,have implications for future studies investigating localized blast injuries,such as blast induced brain and lung injuries.

The past and present of blast injury research in China

With the increasing incidence of blast injury, the research on its mechanisms and protective measures draws more and more attention. Blast injury has many characteristics different from general war injuries or trauma. For example, soldiers often have various degrees of visceral injury without significant surface damage, combined injuries and arterial air embolism. Researchers in China began to investigate blast injury later than the United States and Sweden, but the development is so fast that lots of achievements have been gained, including the development of biological shock tube, the mechanisms and characteristics of blast injury in various organs, as well as protective measures under special environments. This article reviews the past and current situation of blast injury research in China.

Value of lung ultrasound score for evaluation of blast lung injury in goats

Purpose:To establish a severe blast lung injury model of goats and investigate the feasibility of lung ultrasonic score in the evaluation of blast lung injury.Methods:Twenty female healthy goats were randomly divided into three groups by different driving pressures:4.0 MPa group(n=4),4.5 MPa group(n=12)and 5.0 MPa group(n=4).The severe blast lung injury model of goats was established using a BST-I bio-shock tube.Vital signs(respiration,heart rate and blood pressure),lung ultrasound score(LUS),PO2/FiO2 and extravascular lung water(EVLW)were measured before injury(0 h)and at 0.5 h,3 h,6 h,9 h,12 h after injury.Computed tomography scan was performed before injury(0 h)and at 12 h after injury for dynamic monitoring of blast lung injury and measurement of lung volume.The correlation of LUS with PaO2/FiO2,EVLW,and lung injury ratio(lesion volume/total lung volume*100%)was analyzed.All animals were sacrificed at 12 h after injury for gross observation of lung injury and histopathological examination.Statistical analysis was performed by the SPSS 22.0 software.The measurement data were expressed as mean±standard deviation.The means of two samples were compared using independent-sample t-test.Pearson correlation analysis was conducted.Results:(1)At 12 h after injury,the mortality of goats was 0,41.67% and 100%in the 4.0 Mpa,4.5 MPa and 5.0 MPa groups,respectively;the area of pulmonary hemorrhage was 20.00%±13.14% in the 4.0 Mpa group and 42.14%±15.33% in the 4.5 MPa group.A severe lung shock injury model was established under the driving pressure of 4.5 MPa.(2)The respiratory rate,heart rate,LUS and EVLW were significantly increased,while PaO2/FiO2 was significantly reduced immediately after injury,and then they gradually recovered and became stabilized at 3 h after injury.(3)LUS was positively correlated with EVLW(3 h:r=-0.597,6 h:r=-0.698,9 h:r=-0.729;p<0.05)and lung injury ratio(12 h:r=-0.884,p<0.05),negatively correlated with PaO2/FiO2(3 h:r=-0.871,6 h:r=-0.637,9 h:r=-0.658;p<0.05).Conclusion:We established a severe blast lung injury model of goats using the BST-I bio-shock tube under the driving pressure of 4.5 MPa and confirmed that ultrasound can be used for quick evaluation and dynamic monitoring of blast lung injury.

An underpressure generator and its application

A generator to induce simulated underpressure of blast waves has been designed andapplied for the study of underpressure injuries in animals.The generator consists of a vacuumchamber,a vacuum pump,an experimental chamber,a membrane-rupturing device,and apressure-measuring system.When the pressure in the vacuum chamber is reduced with the suc-tion of the vacuum pump to a given level,the membrane separating the vacuum chamber andthe experimental chamber,in which the experimental animal is fixed,is ruptured instantly by asharp pointer.Underpressure occurs in the experimental chamber as soon as its pressure is re-duced rapidly.The physical parameters of the simulated underpressure of blast waves rangefrom-13 to-90 kPa for the peak level,1 to 90 ms for the decreasing time and 14 to 2000 msfor the duration.Animal experimentation with the generator verified that underpressure can in-flict injuries on living bodies as well.

A zebrafish model for hearing loss and regeneration induced by blast wave

Zebrafish have the potential to regrow injured organs and tissues,but their use as a model for hearing regeneration following blast injury has never been reported.In this study,zebrafish were exposed to a blast wave produced by an underwater blast wave generator.The first peak sound pressures produced by this generator were up to 224dB and 160kPa,measured at 25cm away from the machine.Zebrafish hearing sensitivity was examined by analyzing auditory evoked potentials from 1 to 35 days post blast wave exposure.Cell death and cell proliferation in inner ear organs,including the saccule,lagena,and utricle,were investigated using a terminal deoxynucleotidyl transferase deoxyuridine triphosphate nick-end labeling assay,and cell proliferation assay using 5-ethynyl-20-deoxyuridine,respectively.Significant differences in auditory evoked potential thresholds were observed between exposed and control groups,demonstrating both blast wave-induced hearing loss and recovery of hearing sensitivity.An apoptosis assay revealed significantly increased numbers of terminal deoxynucleotidyl transferase deoxyuridine triphosphate nick-end labelingpositive cells in the inner ear sensory epithelia of exposed groups compared with the control group.However,numbers of 5-ethynyl-20-deoxyuridine-positive cells in the inner ear of exposed groups recovered to a normal level within 10 post blast wave exposure.Furthermore,blast wave exposure caused brain injury with increased cell apoptosis and decreased neurogenesis.Compared with drug or noise-induced zebrafish models,our blast wave-induced model elicited more serious hearing loss phenotypes,which required more time to return to a normal level.Overall,this zebrafish model can provide a reliable animal model for both hearing loss and regeneration research.The study was approved by the Shanghai 6th Hospital Animal Care and Use Committee,China(approval No.2017-0196)on February 28,2017.

A Morphometric Study of the Lungs after Blast lnjury in Rats

A lot of research work has been carriod out on thc lungs after blast injury, but nomorphomctric study of the blast-injured lungs has ever been reported so far.The authors quantifiedthe morphological changes of the lungs with blast injury in rats with stereological methods.t wasfound that following the blast injury,the pulmonary capillary volume and the intcmal surface arca de-creased significantly,while the arithmetic and harmonic mean thickness of the air-blood barrier andthe volume of polymorphonuclear leucocytes and platelets in the capillaries incrcased markedly.Themorphometric oxygen diffusion capacity of the lungs was remarkably reduced mainly due to the de-crease of the conductance of the air-blood barrier and erythrocytcs.In addition,the changes of theoxygen diffussion capacity of the lungs were closely related to the partial pressure of arteria/blood oxy-gen.These facts imply that the damage to the pulmonary capillaries was one of the main causes ofalveolar bleeding and early respiratory insufficiency.It is possible that a mathematic relationshipcould be established between the intensity of the blast impact and the consequent morphologicalchanges of the injured lungs.

大鼠密闭管道内爆炸烧冲复合伤及重要器官损伤的观察研究

目的采用密闭管道内气体爆炸方式,建立热辐射与冲击波复合致伤模型,探讨爆炸烧冲复合因素致大鼠重要器官伤情特点。方法8~10周龄雄性SD大鼠72只,体质量(200±10)g,随机分为对照组、轻度组、重度组。采用爆炸冲击波与热辐射致伤系统致大鼠不同程度损伤,并进行物理参数测试,伤后存活大鼠进行呼吸功能检测,24 h后解剖并检测血气、血液生化及血清炎症因子、肺损伤相关蛋白等指标,并观察肺组织及气管病理学形态变化情况。结果爆炸冲击波超压峰值范围为209~493 kPa,温度为152~258℃;轻度组死亡率为8.3%,重度组死亡率为53.1%;与对照组比较,伤后6 h内大鼠吸气时间(inspiratory time,Ti)、潮气量(Tidal Volume,TV)、松弛时间(relaxation time,Tr)增高(P<0.05),呼吸频率(respiratory rate,f)降低(P<0.05);伤后24 h二氧化碳分压(PaCO_(2))、碱剩余值(BE)、碳酸氢根(HCO_(3)^(-))值显著增高(P<0.05),氧分压(PaO_(2))显著降低(P<0.05);血清丙氨酸转氨酶(alanine transaminase,ALT)、天冬氨酸氨基转氨酶(aspartate aminotransferase,AST)、碱性磷酸酶(alkaline phosphatase,ALP)、总胆红素(total bilirubin,TBI)、总胆汁酸(total bile acid,TBA)水平均显著增高(P<0.05),白细胞介素-1β(interleukin-1β,IL-1β)、肿瘤坏死因子-α(tumor necrosis factor-α,TNF-α)、IL-6水平均显著增高(P<0.01);伤后大鼠气管黏膜层有不同程度的出血灶及发炎;肺损伤发生率高且病理表现为点片状出血至整肺叶弥漫性出血,肺泡间隔断裂,间隔增厚,红细胞及炎性细胞浸润,血清肺损伤相关蛋白水平显著增高(P<0.05)。结论建立出高度模拟密闭管道内轻至重度爆炸烧冲复合伤、能够满足研究需要的大鼠模型;爆炸烧冲复合伤以肺损伤、呼吸功能障碍、肝脏损伤及继发性感染为主。

复杂爆炸载荷致肺损伤试验研究

为研究真实工况下人员在爆炸冲击波作用下的动态响应特性,开展某型云爆弹静爆作用下工事内仿人形装置(Anthropomorphic Test Device,ATD)和绵羊的毁伤试验研究。采用爆炸测试装置和简易假人作为研究对象,通过6发爆炸试验分析爆炸冲击波在ATD表面传播规律,开展2种人员损伤预测模型的对比分析。研究结果表明:在本试验工况下,冲击波和崩落的混凝土碎块是主要的毁伤元;爆炸冲击波在ATD表面首先发生反射,随后绕射至其他部位,压力曲线表现出非典型冲击波特征,反射叠加效应明显;在典型冲击波特征正压作用时间区间内,由于Axelsson损伤模型线性阻尼项的影响,求解的胸壁运动速度呈现出先增大至峰值后降低的现象;Axelsson损伤模型与UFC 3-340-02规范相比,在人员损伤预测方面相对保守。所得研究结果可为工程应用及毁伤评估提供参考。

基于动物模型的院前临时VV-ECMO治疗高原重度肺冲击伤的研究

目的通过在高海拔地区进行自由场化爆实验,建立山羊重度肺冲击伤动物模型,探讨临时静脉-静脉体外膜肺氧合(VV-ECMO)技术在现场早期救治中的可行性。方法选择成年山羊16只,按照随机数字表法分为对照组和救治组,每组8只,在海拔4600 m高原环境下建立重度肺冲击伤模型,随后对照组山羊给予呼吸机支持,救治组山羊给予临时VV-ECMO救治。记录伤后15 min山羊存活情况,比较2组山羊伤前和伤后1 h、2 h、3 h生命体征[体温、呼吸频率、心率、平均动脉压(MAP)]及动脉血气分析指标[pH、动脉血氧分压(PO_(2))、动脉血二氧化碳分压(PCO_(2))、动脉血氧饱和度(SaO_(2))、乳酸(LAC)、血钙离子(Ca^(2+))、红细胞压积(HCT)、血红蛋白(Hb)]。对所有死亡和救治结束后处死的山羊进行尸检,采用器官损伤分级(OIS)评估肺损伤严重程度,依据简明损伤评分(AIS)进行肺损伤评分。计算肺组织湿重与干重比值(W/D)和肺系数。结果爆炸后15 min内对照组山羊死亡4只,存活4只;救治组山羊死亡5只,存活3只。2组山羊受伤前后体温、呼吸频率、心率、MAP组间比较,差异均无统计学意义(P>0.05)。救治组山羊伤后1 h、2 h、3 h PO_(2)、SaO_(2)均优于对照组(P<0.05),伤后2 h Ca^(2+)显著高于对照组(P<0.05);2组山羊伤后不同时间点pH、PCO_(2)、LAC、HCT、Hb比较差异均无统计学意义(P>0.05)。2组山羊伤后OIS、AIS、肺系数比较,差异无统计学意义(P>0.05),但对照组肺组织W/D较救治组低(P<0.05)。结论在高海拔地区,我们首次建立了一种新型、可行性强、救治效果稳定的临时VV-ECMO动物救治策略,可以为高原地区重度肺冲击伤现场早期的VV-ECMO救治提供动物实验依据。

诺卡酮对轻度脑爆震伤大鼠抑郁样行为的缓解作用及其机制

目的探究诺卡酮(NKT)对轻度脑爆震伤(bTBI)大鼠抑郁样行为的缓解作用及其机制。方法采用生物激波管分别模拟爆炸超压(BOP)为60 kPa、90 kPa和120 kPa的冲击波建立大鼠bTBI抑郁样模型。BOP暴露后14 d,采用悬尾实验及强迫游泳实验对大鼠抑郁样行为进行评估,选取抑郁样行为最为明显的BOP(120 kPa)进行后续实验。30只大鼠随机分为假手术组、bTBI组(120 kPa BOP暴露)、bTBI+NKT组[120 kPa BOP暴露后第1天开始,经口给药给予NKT 10 mg/(kg·d),共14 d],每组10只。BOP暴露后14 d,采用悬尾实验及强迫游泳实验对大鼠抑郁样行为进行评估;采用Western blotting检测海马组织中蛋白激酶A(PKA)、磷酸化环磷腺苷效应元件结合蛋白(pCREB)及脑源性神经营养因子(BDNF)的表达水平;免疫组化检测海马齿状回区(DG)增殖细胞核抗原(PCNA)标记的神经发生情况。结果90 kPa的BOP暴露即可引起大鼠抑郁样行为,而120 kPa组大鼠BOP暴露后产生的抑郁样行为更明显(P<0.05),据此选取120 kPa的BOP暴露进行后续实验。BOP暴露后14 d,与假手术组比较,bTBI组大鼠悬尾实验不动时间延长(P<0.05),强迫游泳实验潜伏期缩短,不动时间延长(P<0.05),海马组织中PKA、pCREB和BDNF蛋白表达水平降低(P<0.05),海马DG区PCNA阳性神经元数量减少(P<0.05);与bTBI组比较,bTBI+NKT组大鼠悬尾实验不动时间缩短(P<0.05),强迫游泳实验潜伏期延长,不动时间缩短(P<0.05),海马组织中PKA、pCREB和BDNF蛋白表达水平升高(P<0.05),海马DG区PCNA阳性神经元数量增加(P<0.05)。结论早期给予NKT治疗可缓解轻度bTBI大鼠的抑郁样行为,其机制可能与NKT通过激活海马PKA/CREB/BDNF信号通路,使pCREB和BDNF表达水平上调,进而促进海马DG区神经发生有关。

An experimental study on shock wave mitigation capability of polyurea and shear thickening fluid based suspension pads

The present experimental study investigates shock wave mitigation capability of potentially new personal protective equipment(PPE) suspension pads made from polyurea and shear thickening fluid(STF).The shock tube test results show that when placed behind Twaron fabric systems with thickness ranging from 2 mm to 18 mm, the replacement of conventional flexible foam pad with STF and STF-infused foam pads with the same thickness of 20 mm greatly reduces the normalized peak pressure(by about 72% for each pad). However, this benefit is partially offset by a large increase in the normalized impulse(by about78% for the STF pad and 131% for the STF-infused foam pad) which may cause the shock wave mitigation performance of these two pads to become less effective. Interestingly, the use of 4 mm thick polyurea pad can greatly reduce the normalized peak pressure and impulse as well(by about 74% and 49%, respectively). These results reveal that among the potentially new suspension pads tested, the polyurea pad displays the best shock wave mitigation performance. Therefore, polyurea has potential for use as a suspension pad in personal protective equipment requiring shock wave mitigation capability such as fabric ballistic vests, bomb suits and combat helmets.

球形爆炸冲击波正面作用下人体头部损伤规律的数值模拟

在军事行动、恐怖袭击和工业事故等爆炸事件中,爆炸冲击波引起的头部损伤已成为主要致伤形式之一。为了阐明冲击波损伤规律及头部承受冲击波损伤阈值,针对不同冲击波入射压力对人体颅脑不同部位的损伤规律进行了研究。建立了头部三维有限元模型,验证了其有效性。建立了冲击波-头部流固耦合模型,在大脑表面沿正中矢状面选取5个特征点,对头部分别在1 000 kPa、800 kPa、600 kPa、400 kPa、300 kPa、200 kPa、100 kPa和50 kPa入射冲击波作用下的损伤情况进行分析。在球形冲击波的作用下,颅骨分散冲击波,为脑组织提供防护;冠状面前侧的特征点受压,后侧特征点受拉;入射冲击波超压大于600 kPa时,距离爆源越近的特征点压力越大,距离爆源越远的特征点压力越小;造成颅脑组织80%严重损伤的入射冲击波超压临界值约为137 kPa。

颅脑爆炸伤数值模拟研究进展:建模、力学机制及防护

爆炸致创伤性脑损伤是现代战争和爆炸事故中最常见的伤亡之一。近年来由爆炸波引起的轻度原发性颅脑冲击伤在士兵伤患中占大多数,引起了研究人员重视。由于伦理和技术方面的限制,人体爆炸实验难以开展,数值模拟已经成为研究颅脑爆炸伤的重要手段之一。合理的物理建模结合可靠的模型和参数,能够定量给出爆炸冲击波作用下人体头部和大脑的生物力学响应,揭示大脑损伤的力学机制,这些对于认识颅脑爆炸伤的生物力学特性以及单兵防护装备的设计和优化都具有重要的意义。本文旨在为研究人员提供有关原发性颅脑爆炸伤数值模拟方面研究现状的背景信息,以及在计算建模、力学机制和防护3个方面的进展。重点针对大脑的多尺度性质及颅脑爆炸伤的生物力学建模,介绍了脑组织的线弹性、超弹性和黏超弹性本构模型,人头有限元模型在大脑结构、网格尺寸等方面的发展和演化,以及颅脑爆炸伤的宏观、介观和多尺度建模和数值模拟方法。针对颅脑爆炸伤的波传播直接作用、脑血管系统的影响,以及全身响应的连续过程,分析和讨论了数值模拟得到的力学机制证据。介绍了颅脑爆炸伤防护策略的数值模拟研究进展,如提高头部封闭性的重要性、新结构和新材料的应用。最后,对当前颅脑爆炸伤的数值模拟研究和应用进行了总结,并确定了未来需要发展和改进的地方。

爆炸冲击波致大鼠抑郁样行为及其初步机制

目的观察爆炸冲击波引起的轻度脑爆震伤(mbTBI)模型大鼠抑郁样行为改变及其海马中c AMP-PKACREB-BDNF信号通路变化,探讨mbTBI导致神经功能障碍的相关机制。方法44只雄性SD大鼠随机分为对照组和模型组,每组22只。模型组大鼠放入带网格的铁笼内,头部朝向爆心,呈扇形固定于距离爆心15 m的地面,同时检测大鼠布放位置的冲击波强度。爆炸结束后,每组随机选取7只大鼠分笼饲养,于暴露后7、14、28 d,分别采用旷场实验和高架十字迷宫实验评价大鼠的抑郁样行为;每组剩余大鼠分别于暴露后7、14、28 d各随机处死5只,取海马组织并提取蛋白,采用Western blotting检测环磷酸腺苷(cAMP)、蛋白激酶A(PKA)、环磷腺苷效应元件结合蛋白(CREB)、磷酸化CREB(p-CREB)、脑源性神经营养因子(BDNF)及原癌蛋白c-FOS的相对表达量。结果爆炸试验后模型组大鼠全部存活,但24 h内精神萎靡、行动迟缓、食欲差,72 h后上述症状逐渐缓解;两组大鼠各时间点的体重差异均无统计学意义(P>0.05)。行为学实验结果显示,与对照组比较,爆炸试验后14 d模型组大鼠的移动总距离、中央区域停留时间、进入开放臂的次数及时间占比均明显减少或降低(P<0.05);爆炸试验后28 d,两组大鼠中央区域停留时间、进入开放臂的次数占比差异无统计学意义(P>0.05)。Western blotting检测结果显示,与对照组比较,爆炸试验后7、14、28 d模型组大鼠海马组织PKA、CREB、p-CREB和BDNF蛋白表达量均明显降低(P<0.05);爆炸试验后7、14 d模型组大鼠海马组织cAMP、c-FOS表达量明显降低(P<0.05),而28 d时两组差异无统计学意义(P>0.05)。与爆炸试验后7、14 d比较,爆炸试验后28 d模型组大鼠海马组织PKA、CREB和BDNF表达量均明显升高(P<0.05)。结论单次爆炸冲击波暴露可引起大鼠抑郁样行为,其机制可能与海马组织cAMP-PKA-CREB-BDNF信号通路下调有关。