Silicon carbide resonant tuning fork for microsensing applications in high-temperature and high G-shock environments

We present the fabrication and testing of a silicon carbide(SiC)balanced mass double-ended tuning fork that survives harsh environments without compromising the device strain sensitivity and resolution bandwidth.The device features a material stack that survives corrosive environments and enables high-temperature operation.To perform high-temperature testing,a specialized setup was constructed that allows the tuning fork to be characterized using traditional silicon electronics.The tuning fork has been operated at 600 ℃ in the presence of dry steam for short durations.This tuning fork has also been tested to 64 000 G using a hard-launch,soft-catch shock implemented with a light gas gun.However,the device still has a strain sensitivity of 66 Hz/με and strain resolution of 0.045 με in a 10 kHz bandwidth.As such,this balanced-mass double-ended tuning fork can be used to create a variety of different sensors including strain gauges,accelerometers,gyroscopes,and pressure transducers.Given the adaptable fabrication process flow,this device could be useful to micro-electro-mechanical systems(MEMS) designers creating sensors for a variety of different applications.

Study on the thermal protection performance of superalloy honeycomb panels in high-speed thermal shock environments

The thermal protection performance of superalloy honeycomb structure in high-temperature environments are important for thermal protection design of high-speed aircrafts. By using a self-developed transient aerodynamic thermal simulation system, the thermal protection performance of superalloy honeycomb panel was tested in this paper at different transient heating rates ranging from 5℃/s to 30℃/s, with the maximum instantaneous temperature reaching 950℃. Furthermore, the thermal protection performance of superalloy honeycomb struc- ture under simulated thermal environments was computed for different high heat- ing rates by using 3D finite element method, and a comparison between calcu- lational and experimental results was carded out. The results of this research provide an important reference for the design of thermal protection systems com- prising superalloy honeycomb panel.

High temperature effects in moving shock reflection with protruding Mach stem

The influence of high temperature effects on the protrusion of Mach stem in strong shock reflection over a wedge was numerically investigated. A two-dimensional inviscid solver applies finite volume method and unstructured quadrilateral grids were employed to simulate the flow. Theoretical analysis was also conducted to understand the phenomenon. Both numerical and theoretical results indicate a wall-jet penetrating forward is responsible for the occurrence of Mach stem protrusion. The protrusion degree seems to depend on the thermal energy buffer capacity of the testing gas. Approaches to increase the energy buffer capacity, such as vibrational relaxation, molecular dissociation, and increase of frozen heat caoacitv, all tend to escalate the orotrusion effect.

The Ultracytochemical Effects of High Energy Shock Wave on Rabbit Liver

The ultracytochemical effects in the liver of rabbit undergoing high energy shock wave (HESW) were studied with electron microscope. The application of lanthanum as a tracer for ultrastructural study demonstrated that intracellular lanthanum could be observed, most of which entered the hepatocytes and its mitochondria. The lanthanum granules were also found to deposite in the zone of tight junctions of bile canaliculi, which indicated that the tight junctions had been damaged. The activities of succinate dehydrogenase (SDH) in liver cells, alkaline phosphatase (ALP) and thiamine pyrophosphatase (TPPase) on the wall of bile canaliculi became diminished obviously. Both the activites and localizations of TPPase had changed. Some TPPase from the damaged lysosome like vesicles and Golgi saccules of liver cells discharged into cytoplasm. TPPase reaction production in some bile canaliculi decreased. In the intercellular space of the liver cells and the tight junctions of bile canaliculi TPPase reaction could be seen. Ultrastructurally, the changes commonly seen were hydropic mitochondria and dilatation of rough endoplasmic reticulum. Serologic test demonstrated that there was an abnormal change of SGPT, SGOT and ALP. The results showed that HESW can damage the ultrastructure and function of liver.

Effects of Heat Shock Factor AtHsfA1a on Caspase-3 Activity in Arabidopsis thaliana under High Temperature Stress

[ Objective] This study aimed to investigate the effects of heat shock factor AtHsfAla on Caspase-3 activity in Arabidopsis thaliana under high tempera-ture stress, thus revealing the relationship between heat shock factor AtHsfAl a and programmed cell death in A. thaliana. [ Method ] Different genotypes of A. thaliana （AtHsfAla-silenced transgenic and wild-type） seedlings were treated at 42 ℃. According to the fragmentation level of fluorogenic substrate Ac-DEVD- pNA, Caspase-3 activity was determined by spectrophotometry. [ Result] After high temperature treatment, Caspase-3 activity in A. thaliana was enhanced signifi-cantly. Caspase-3 activity in AtHsfAla-si／enced transgenic A. thaliana was higher than that in wild-type A. thaliana, which indicated that AtHsfAla could inhibit Caspase-3 activity in A. thaliana under high temperature stress. [ Conclusion] Under high temperature stress, heat shock factor AtHsfAla might exert inhibitory effects on programmed cell death by reducing Caspase-3 activity. This study provided the basis for clarifying the mechanism of stress resistance in plants.

A COMPARISON OF FOUR RECENT NUMERICAL SCHEMES GIViNG HIGH RESOLUTION OF SHOCK WAVE AND CONCENTRATED VORTEX

In recent ten years high resolution difference schenies for the computation of thefull unsteady Eulerian system of equations for invisid compressible gas finds celebratedprogress. This paper tests furtherly, by a complex two-dimensional unsteady problem,four recent schemes. to them attentions are paid. The test problem is the initial stageof a two-dimensional diffraction and reflection of a plane shock wave, impinging on arectangular obstacle. At whose top side there are two sharp corners, near which flow.parameters finds severe variation. There is occurrence of expansion fan with a centerand also concentrated vortices. To simulate them well, the schemes should have goodadaptivity. The special shock Mach number M,=2.068 is so chosen, that at this M,the partical velocity behind impinging shock in fixed coordinate system is just equal tothe speed of sound there, this condition also occurs along a curve in the region ofexpansion fan with a center at the corner. This can clarify the computational featureof different schemes in case,when one of the eigenvalues is just zero. Zero eigenvaluemay spoil some schemes locally. Graphical visualization of the computational resultsmay, show features of the tested schemes about the shock wave resolution, schemeviscosity, expansion wave and the ability. to simulate the process of the generation ofunsteadv concentrated vortex.

A study of therapeutic effects of 7.5% NaCl-6% dextran 70 in small dosage on hemorrhagic shock at high altitude in dogs

The effects of 7.5％ NaCl-6％ dextran 70 in small dosage on the cardiovascular func-tion and the survival rate in hemorrhagic shock at a simnlated altitude of 4000 m were observedin dogs.The animals were bled from the femoral artery for 8 rain to reduce the mean arterialpressure to 5.73±0.1kPa,which was maintained for an hour.Then the dogs were intravenouslyinjected with 4ml/kg 0.9％ NaCL(NS group,n=7),7.5％ NaCl(HS group,n=6)and 7.5％Naa-6％ dextran 70(HSD group,n=6)respectively.In the 2-hour-period after injection,5out of 7 dogs of NS group died but only 1 out of the 6 of both the HS and HSD groupsdied.Significant increase of mean arterial pressure,left ventricular pressure,±dp/dt max of leftventricle,cardiac output,cardiac index and cardiac minute work index was observed in both theHS and HSD groups.Improvement of the cardiovascular function was even more marked inHSD group than in HS group,thougth the difference between the 2 groups was statisticallyinsignificant.There was a tendency for the pulmonary vascular resistance to decrease in HS andHSD groups as compared with the NS group.The percentage of plasma expansion of HSDgroup was larger than that of HS group(P【0.05)and of NS group(P【0.01),but nosignificant difference existed between the HS and NS groups.It is believed that intravenous injection of hypertonic saline alone or in combination with dextran is effective for the treatment ofhemorrhagic shock at high altitude and the combination of 7.5％ NaCl and 6％ dextran 70seems even more effective.

Influence of High Temperature on the Expression of Arabidopsis Heat Shock Transcription Factor AtHsfA1a

[ Objective] This study ~med to investigate the influence of high temperature on the expression of heat shock transcription factor AtHsfAla in different genotypes of Arabidopsis. [ Method ] Arabidopsis plants overexpressing heat shock transcription factor AtHsfA1 a were used as experimental materials and treated un- der high temperature at 39℃ for 1 rain and 5 min; total RNA of AtI-IsfAla was extracted, and the reverse transcription and amplification were conducted using RT- PCR technology, the amplification products were detected by electrophoresis. [ Result ] The expression levels of AtHsfA1 a in Arabidopsis plants overexpressing heat shock transcription factor AtHsfAla at high temperature and room temperature were higher than wild-type Arabidopsis; the expression levels of AtHsfAla in both wild-type Arab/dops/s and transgenic Arabidopsls plants overexpressing heat shock transcription factor AtHsfAla at high temperature of 39 ~C were higher than that at room temperature of 25 ~C, but the expression levels of AtHsfAla in wild-type Arab/dops/s and transgenic Arab/dops/s plants overexpressing heat shock transcription factor AtHsfAla varied little after high temperature treatment at 39 ~C for 1 rain or 5 rain. [ Conclusion] The expression of AtHsfAla is induced rapidly by high tem- perature, thus regulating the expression of early adversity-resistant genes. This study will lay the foundation demonstrating the mechanism of Arabidopsis heat shock transcription factor AtHsfAla.

Study of damage to a high concrete dam subjected to underwater shock waves

To study the effect of a strong underwater shock wave on a concrete dam, this research aims to improve hammer impact methods in model tests. Six 1:200 scale models were designed and tested under distributed impact loads. A device was deployed for a direct measurement of the impact force at the upstream face of the dams. The model dam bases were anchored to prevent displacement. The experimental results indicate that the top part of the concrete dam is a weak zone, and the impact failure initiates with a fracture on the top of the dam. The peak value of impact stress increases when the second crack appears in the concrete dam from the upstream face to the downstream face. And, the level of the second crack in the dam body is lower as the peak value of impact stress increases. In this study, dynamic analysis was conducted by calculating the results to verify the effectiveness of a device to directly measure the impact force. This method may be used to approximately forecast the damage of concrete dam and may also be useful in other engineering applications.

Study on the shock absorbing technique of high speed railway bridges

Based on the idea of "bearing function separation", a structural member called shock absorber that makes use of its plastic deformation is presented for reducing the seismic response of the bridge. The design criterion for matching material stress, strain and earthquake fortification aim, is also given. The analysis results show that the high speed railway box girder with the absorber in this paper has great reduction effect in seismic response of the bridge piers.

马赫数10条件下冲压发动机内氢气燃烧特性试验

针对高马赫数超燃冲压发动机面临的高效燃烧组织挑战,本文提出了一种凹腔后缘激波强化的高马赫数超声速燃烧组织技术,并设计了一套燃烧室采用双侧对称布置凹腔结构的三维发动机试验模型。采用OH*基化学发光光谱诊断与壁面测压相结合的试验手段,在自由活塞驱动激波风洞的名义Ma=10流场中,对凹腔上游横向氢气射流的燃烧特性进行了研究,并讨论了模拟流场的重复性,给出了氢气燃烧演化特征、火焰稳定结构及释热特性。不同车次的总压等流场参数表明试验流场具有较高的重复性,可保障氢气燃烧特性的可复现性。通过观察试验过程中OH*基动态发光特征发现,在高焓激波风洞发动机试验中采用燃料提前喷注的方法使发动机流道在空气主流到来之前充盈大量的氢气,进而在主流到达发动机内的瞬间形成所谓“激波管流动-燃烧”效应,使来流空气与氢气接触面发生自点火与剧烈燃烧,产生显著不同于发动机正常工作情况下的点火与燃烧机制,但随着主流趋于平稳,“激波管流动-燃烧”效应消失,在高总温气流的自点火效应与凹腔后缘的X型激波耦合作用下,火焰稳定在凹腔上游近壁面区的氢气射流尾迹区和凹腔后缘附近的全流场中。通过分析壁面压力分布特征发现,凹腔后缘的X型激波实现了燃烧的强化与火焰的稳定,并获得了最显著的释热压升。这些结果表明高马赫数冲压发动机可利用凹腔后缘X型激波强化燃烧和稳定火焰。

Modeling of the Coupling of the Lightning Shock Wave Flow Circuit in the High Voltage Electrical Network

This article focuses on the aggression of lightning overload on the equipment of the electrical network of sites where storm activity is very dense;and the electrocution of people located in the direct environment of the high-voltage substation during the flow of lightning current to the ground through the ground socket. The modeling of the flow circuit of the shock wave consisting of guard wire, lightning arrester and ground socket couple to the transformer of the high voltage substations, thanks to the approach of a servo block, led to the synthesis of a PID regulator (corrector) whose action is to reject the effects of the overvoltage on the network equipment and to significantly reduce or even cancel the effects of the step or touch voltage due to the distribution of the potential around the ground socket;and thus improve the quality of service of the high-voltage transmission and distribution electricity network, especially in stormy times.

射弹高速撞击下结构冲击响应建模方法

装备受到外界打击可能造成失效,以往的研究多集中在打击部位的损伤破坏,而对于打击引起的冲击波及其在装备内传播研究较少,而后者同样能够导致装备失效。本文针对结构在高速撞击下的冲击响应问题开展了建模方法研究,提出了结构在高速打击下的冲击源建模方法,并通过理论分析给出了建模方法的适用条件。利用传统的有限元技术,结合本文的冲击源建模方法,可以有效地对结构高速撞击下的冲击响应进行仿真,通过试验验证了方法的适用性。

Effects of mechanical boundary conditions on thermal shock resistance of ultra-high temperature ceramics

The effects of mechanical boundary conditions, often encountered in thermalstructural engineering, on the thermal shock resistance（TSR） of ultra-high temperature ceramics（UHTCs） are studied by investigating the TSR of a UHTC plate with various types of constraints under the first, second, and third type of thermal boundary conditions. The TSR of UHTCs is strongly dependent on the heat transfer modes and severity of the thermal environments. Constraining the displacement of the lower surface in the thickness direction can significantly decrease the TSR of the UHTC plate, which is subject to the thermal shock at the upper surface. In contrast, the TSR of the UHTC plate with simply supported edges or clamped edges around the lower surface is much better.

血清超敏C反应蛋白、胱抑素C与脓毒性休克患者心功能、肾功能损伤的关系

目的检测脓毒性休克患者血清超敏C反应蛋白(hs-CRP)、胱抑素C(Cys C)水平,探讨其与脓毒性休克患者心功能、肾功能损伤的关系。方法选取2020年5月—2023年12月我院收治的脓毒性休克患者50例,纳入休克组。另选取同期健康体检者48名,纳入参照组。比较2组研究对象hs-CRP、Cys C水平,分析脓毒性休克患者血清hs-CRP、Cys C水平与患者左室射血分数(LVEF)、二尖瓣舒张早期血流峰速(E)/二尖瓣环舒张早期速度(E’)、血浆脑钠肽(BNP)、心肌肌钙蛋白Ⅰ(c TnⅠ)、肾小球滤过率(GFR)及急性生理学与慢性健康状况评分系统Ⅱ(APACHEⅡ)评分的关系。结果2组研究对象年龄、性别分布、身体质量指数(BMI)及基础疾病患病情况等方面的差异均无统计学意义(P>0.05)。休克组患者的血清hs-CRP水平[(181.01±37.39)mg/L]和血清Cys C水平[(2.62±0.25)mg/L]显著高于参照组[(38.78±10.55)mg/L、(0.96±0.15)mg/L],差异均有统计学意义(P<0.05)。休克组患者的血清hs-CRP水平与LVEF、E/E’、BNP、c TnⅠ水平、APACHEⅡ评分有关(P<0.05),与GFR无相关性(P>0.05);休克组患者的血清Cys C水平与GFR水平、APACHEⅡ评分有关(P<0.05),与LVEF、E/E’、BNP及c TnⅠ水平均无相关性(P>0.05)。结论脓毒性休克患者血清hs-CRP、Cys C水平均显著高于健康体验者,推测其可能与心肌细胞受损、炎症因子水平升高、肾血流量降低等因素有关,可作为评估脓毒性休克患者心、肾功能损伤的参考指标。

高能束表面改性技术在航空领域的应用

高能束表面改性适用于各种金属和合金,能够显著提升材料表面硬度、耐磨、耐蚀等性能指标,是航空部件实现性能提升的有效手段之一。本文总结了6种高能束表面改性技术的基本原理、设备构成和改性应用,其中激光相变硬化通过马氏体相变强化金属材料表面;激光熔覆通过选择不同粉末实现表面修复和表面性能提升,重点在于控制裂纹缺陷;激光冲击强化可有效解决航空发动机部件高周疲劳断裂问题;强流脉冲电子束和强流脉冲离子束一方面需要提高设备的性能和运行稳定性,另一方面要针对航空部件应用开展深入研究;而离子束辅助沉积则可以通过制备固体润滑涂层实现对微动磨损的有效防护。最后,提出对高能束表面改性机理深入研究、发展专业化智能化装备和实现多种束源复合与集成的发展方向。

老年糖尿病合并肺部感染患者病原菌分布及血清HSP70、HMGB1水平与病情严重程度和预后的关系

目的探讨老年糖尿病合并肺部感染患者病原菌分布情况,分析血清热休克蛋白70(HSP70)、高迁移率族蛋白B1(HMGB1)水平与病情严重程度和预后的关系。方法选择2021年1月—2023年11月西安交通大学第一附属医院呼吸内科与危重症医学科收治的2型糖尿病(T2DM)合并肺部感染患者253例为研究对象,根据出院时预后情况分为预后良好组(n=191)和预后不良组(n=62)。鉴定患者痰液中病原菌并检测血清HSP70和HMGB1水平;采用多因素Logistic回归分析老年T2DM合并肺部感染预后的影响因素;受试者工作特征曲线(ROC)分析血清HSP70和HMGB1水平对老年T2DM合并肺部感染预后的预测价值。结果预后不良组患者年龄、空腹血糖(FPG)、高血压、慢性阻塞性肺疾病(COPD)及病情重度占比显著高于预后良好组(t/χ^(2)/P=6.251/<0.001、14.949/<0.001、4.666/0.031、5.827/0.016、16.530/<0.001)。253例患者痰标本中共检出病原菌株298株,其中革兰阴性菌占比65.10%(194/298)、革兰阳性菌占比28.86%(86/298)、真菌占比6.04%(18/298)。预后不良组血清HSP70和HMGB1水平明显高于预后良好组(t=11.672、13.069,P均<0.001)。血清HSP70和HMGB1水平比较,重度>中度>轻度患者(F=54.146、231.257,P均<0.001);多因素Logistic回归显示,年龄大、HSP70高、HMGB1高、FPG高、COPD及严重程度重均为老年T2DM合并肺部感染预后的危险因素[OR(95%CI)=1.322(1.015~1.722)、1.993(1.336~2.973)、1.754(1.302~2.363)、1.876(1.401~2.512)、3.016(1.798~5.060)、3.956(2.208~7.718)];血清HSP70、HMGB1及二者联合预测老年T2DM合并肺部感染预后的曲线下面积(AUC)分别为0.785、0.772、0.897,二者联合优于各自单独预测效能(Z=3.452、3.297,P均<0.001)。结论血清HSP70、HMGB1水平与老年T2DM合并肺部感染严重程度和预后密切相关,二者联合对其预后具有较高预测价值。

蛹期高温对稻纵卷叶螟种群的抑制作用

【目的】本研究旨在明确稻纵卷叶螟Cnaphalocrocis medinalis蛹对高温的敏感性,为利用蛹期高温预测种群发展趋势提供生物学指标和模型。【方法】对稻纵卷叶螟1-5日龄蛹分别在37,39和41℃下进行1次性1-7 h的热击,对1日龄蛹在37,39和41℃进行1-7 h/d持续2和3 d的多次热击,并以一直饲养在27℃下的蛹为对照组,测定热击处理组和对照组蛹羽化率、蛹历期、每雌产卵量及卵孵化率;采用线性回归方法建立蛹羽化率、蛹历期、每雌产卵量及卵孵化率与热击时长的关系模型。【结果】与对照组相比,1-5日龄稻纵卷叶螟蛹分别受37,39和41℃高温1次性热击1-7 h后,随着热击温度的升高蛹历期延长,蛹羽化率、每雌产卵量和卵孵化率降低;在相同的高温下,随着热击时间的增长蛹历期呈线性延长,蛹羽化率、每雌产卵量和卵孵化率呈线性下降,并且变化率在各日龄处理间基本相同;37或39℃热击后,1日龄蛹组的蛹历期长于3-5日龄蛹组的,但前者的蛹羽化率低于后者。1日龄蛹在37和39℃下多次热击后蛹历期随日热击时间的增长而缩短,在41℃下仅2 d内的热击有该趋势,3 d内7 h/d的热击延长了蛹历期;蛹羽化率、每雌产卵量及卵孵化率均随日热击时长的延长而线性降低,并且降低幅度随温度的升高而增大,但在热击2和3 d间无显著差异。37,39和41℃下2和3 d,日热击时长每延长1 h蛹羽化率将分别降低3.25%,4.95%和7.49%,每雌产卵量分别减少5.02%,7.80%和10.82%,卵孵化率分别降低2.20%,3.31%和5.05%,说明热击显著抑制了种群的发展。【结论】稻纵卷叶螟蛹对高温较为敏感,热击影响其发育、存活和繁殖力,可根据蛹期高温及持续时长预测稻纵卷叶螟种群的数量。

大尺寸自由活塞激波风洞自由流参数诊断方法

高焓激波风洞自由流具有一定程度的热化学非平衡,使得流场参数的确定存在困难。针对大尺寸自由活塞高焓激波风洞的总温2 700~4 700 K、总压5.6~20.3 MPa条件,采用非接触吸收光谱技术、接触测量技术等测试技术,结合多温度多组分数值模拟方法,共同诊断喷管名义马赫数10出口自由流的参数。结果显示,温度测量值与计算值最大偏差小于7.5%,速度测量值与计算值最大偏差小于5%,NO浓度测量值与计算中最大偏差小于12%。