Synthesis and anti-shock activity of divalent β-D-galactopyranosyl-(1→4)-β-D-glucopyranosides

Three divalent β-D-galactopyranosyl-（1 → 4）-β-D-glucopyranosides were synthesized using acetylated lactosyl bromide as donor and polyethylene glycols with different polymeric degree （n = 4, 5, 6） as linker, and evaluated for in vivo inhibitory activity to leukocyte-endothelial cell adhesion on severe bum-shock rats. The result showed that the length of linkers had apparent influence on anti cell adhesion activity.

Numerical simulation of the anti-shock performance of a gear case

Both sea battles and testing of ship in underwater explosions reveal unacceptably poor anti-shock performance of important shipboard equipment. Anti-shock performance of shipboard equipment is a significant factor determining fighting strength and survivability. The anti-shock performance of a shipboard gear case based on BV043/85 was investigated using numerical simulation. A geometric model of the gear case was built using MDT software and meshed in HyperMesh software, and then the finite element model of the gear case was formed. Using ABAQUS software, the anti-shock performance of the gear case was simulated. First, shock response of typical regions of gear case was determined. Next, some generalizations were made about the anti-shock performance of the gear case by analyzing the Mises stress of typical regions varied with shock inputs. Third, weak regions were determined from simulation results. The threshold values of shock resistance of the gear case at different impulse widths were obtained through interpolating the numerical simulation results selected from the most dangerous spot. This research provides a basis for further optimization of the design of gear cases.

A novel anti-shock silicon etching apparatus for solving diaphragm release problems

This paper presents a novel anti-shock bulk silicon etching apparatus for solving a universal problem which occurs when releasing the diaphragm （e.g. SiNx）, that the diaphragm tends to be probably cracked by the impact of heatinginduced bubbles, the swirling of heating-induced etchant, dithering of the hand and imbalanced etchant pressure during the wafer being taken out. Through finite element methods, the causes of the diaphragm cracking are analysed. The impact of heating-induced bubbles could be the main factor which results in the failure stress of the SiNx diaphragm and the rupture of it. In order to reduce the four potential effects on the cracking of the released diaphragm, an anti-shock hulk silicon etching apparatus is proposed for using during the last etching process of the diaphragm release. That is, the silicon wafer is first put into the regular constant temperature etching apparatus or ultrasonic plus, and when the residual bulk silicon to be etched reaches near the interface of the silicon and SiNx diaphragm, within a distance of 50-80μm （the exact value is determined by the thickness, surface area and intensity of the released diaphragm）, the wafer is taken out carefully and put into the said anti-shock silicon etching apparatus. The wafer＇s position is at the geometrical centre, also the centre of gravity of the etching vessel. An etchant outlet is built at the bottom. The wafer is etched continuously, and at the same time the etchant flows out of the vessel. Optionally, two symmetrically placed low-power heating resistors are put in the anti-shock silicon etching apparatus to quicken the etching process. The heating resistors＇ power should be low enough to avoid the swirling of the heating-induced etchant and the impact of the heating-induced bubbles on the released diaphragm. According to the experimental results, the released SiNx diaphragm thus treated is unbroken, which proves the practicality of the said anti-shock bulk silicon etching apparatus.

Frequency Analysis and Anti-Shock Mechanism of Woodpecker＇s Head Structure

The mechanical properties of the skull and the anti-shock characteristics of woodpecker＇s head were investigated by ex- periment and numerical simulation. We measured the micro-Young＇s modulus of the skull by nano-indentation method and calculated the macro-equivalent Young＇s modulus of the skull at different positions using homogenization theory. Based on the Computerized Tomography （CT） images of woodpecker head, we then built complete and symmetric finite element models of woodpecker＇s skull and its internal structure and performed modal analysis and stress spectrum analysis. The numerical results show that the application of pre-tension force to the hyoid bone can increase the natural frequency of woodpecker＇s head. The first natural frequency under the pre-tension force of 25 N reaches 57 Hz, which is increased by 21.3% from the non-pre-tension state and is more than twice the working frequency of woodpecker （20 Hz 25 Hz）. On the application of impact force to the tip of beak for 0.6 ms, high magnitudes of stress component occur at around 100 Hz and 8,000 Hz, far away from both the working frequencies and the natural frequencies of woodpecker head. The large gaps among the natural, working and stress response frequencies enable the woodpecker to effectively protect its brain from the resonance injury.

Energy conversion in woodpecker on successive peckings and its role on anti-shock protection of brain

To investigate the mechanism of brain protection of woodpecker,we built a finite element model of a whole woodpecker using computed topography scanning technique and geometry modeling.Dynamic analyses reveal:(i)99.7%of the impact energy is converted into strain energy in the bulk of body and 0.3%is converted into strain energy in the head after three successive peckings,indicating the majority of the impact energy is stored in the bulk of body;(ii)the strain energy in brain is mainly converted into the dissipated energy,alleviating the mechanical injury to brain;(iii)the deformation and the effective energy dissipation of the beaks facilitate the decrease of the stress and impact energy transferred to the brain;(iv)the skull and dura mater not only provide the physical protection for the brain,but also diminish the strain energy in the brain by energy dissipation;(v)the binding of skull with the hyoid bone enhances the anti-shock ability of head.The whole body of the woodpecker gets involved in the energy conversion and forms an efficient anti-shock protection system for brain.

Anti-shock loading capability of a fluidized-bed flocculator

The efficiency of a fluidized-bed flocculator with 800-um particles of 1360 kg/m3 in density was studied, and the anti-shock capability of the unit was estimated for three kinds of industrial wastewater： heavy turbidity wastewater, dispersed dyeing wastewater and starch wastewater. Steady removal efficiency was contributed by the following characteristics of the flocculator： （1） the dynamic conditions, flocculation time and velocity gradient, which were stabilized at a steady level as the loading rate changed; （2） hydrodynamic characteristics, especially the considerable rise of expanded bed height with increasing superficial velocity when small and light particles were employed as the solid phase; （3） flocs growth characteristics in the fluidized bed, which caused the density and size of the flocs being maintained at a compensational relationship, resulted the stabilized settling velocity of the flocs.

反倾销嵌入全球生产网络的级联效应仿真研究

本研究将复杂网络理论应用于投入产出模型并将其引入宏观经济学生产函数理论模型,对反倾销嵌入全球生产网络的内在机理与其产生的级联效应展开探讨与仿真模拟分析.研究发现:基于网络视角与投入产出关系,反倾销冲击对中间产品的贸易抑制作用要明显大于最终产品,多次跨境的中间品将会累积增加反倾销带来的贸易成本;反倾销带来的行业引致需求量降低与出口贸易受到抑制以及行业与国家总产出水平的波动等影响,会沿着以中间品贸易为基础的全球生产网络中的投入产出关系进行传播,从而产生显著的级联效应,并且该效应会随着不同国家-部门节点之间的联系紧密程度(贸易量)的降低而衰减;反倾销产生的级联效应不仅涉及全球生产网络中直接关联节点即涉案国(调查国与被调查国)的国内上下游行业,而且波及间接关联节点即非涉案国的第三方国家和地区,进而影响全球多边贸易发展,同时,级联效应也阻碍了网络节点参与全球价值链生产分工,导致了节点隶属国(地区)的国内价值链被拉长;反倾销嵌入全球生产网络后,会通过整个生产网络产生总量波动效应,从而改变全球生产网络的拓扑结构,即全球生产网络变的相对稀疏、节点间网络距离拉长等.

兔抗人胸腺细胞免疫球蛋白致患儿严重过敏性休克2例的护理

本研究回顾性分析2例患儿在造血干细胞移植预处理阶段中,使用兔抗人胸腺细胞免疫球蛋白(rATG)出现严重过敏性休克现象。经验总结包括:全面评估病史,精准识别过敏风险;规范用药流程,严格执行预防措施;常态化应急演练,确保快速高效抢救;实施人文关怀,缓解焦虑情绪。经过及时有效的抢救治疗,2例患儿均顺利度过预处理阶段,成功完成造血干细胞移植手术,分别在术后28 d和23 d好转出院。

敷设抗冲覆盖层的双层圆柱壳抗冲性能研究

[目的]旨在研究双壳体潜艇非接触水下爆炸下的抗冲性能,提出在壳体表面敷设抗冲覆盖层的防护方法,以内壳冲击响应为评价指标,研究不同敷设方式下的抗冲击效能。[方法]采用声−固耦合法,建立外流场−外壳体−舷间水−内壳体的非线性流−固耦合冲击动力学模型,对内外壳外表面均敷设覆盖层(工况2)、仅内壳外表面敷设覆盖层(工况3)和仅外壳外表面敷设覆盖层(工况4)情况下的壳体冲击响应及覆盖层抗冲击效能进行对比分析。[结果]结果表明,对于工况2,内壳体迎爆面不同测点处的加速度、速度和位移峰值平均降低量分别达94.1%,81.2%和23.3%,周向和纵向微应变峰值平均降低量达67.7%和88.3%;对于工况3,相应值分别为60.4%,45.4%和−2.1%,以及34.6%和68.0%;对于工况4,相应值分别达86.7%,75.1%和20.3%,以及68.6%和77.8%。[结论]针对双壳体潜艇,在壳体上敷设抗冲覆盖层可有效降低内壳冲击响应,尤其是加速度和速度响应。在外壳体外表面上敷设覆盖层时的抗冲击效果更好。

FMEA联合PDCA在感染性休克1 h抗生素使用中的应用

目的探讨失效模式与效应分析(failure model and effect analysis,FMEA)联合PDCA管理工具在感染性休克患者1 h抗生素使用中的效果。方法选取河北医科大学第二医院收治的感染性休克患者177例及医护人员32例为研究对象。采用不同时间段分组,2组医护人员相同。以2022年1—6月的感染性休克患者87例及医护人员32名为对照组。以2022年7—12月90例感染性休克患者及32名医护人员为观察组。对照组采用常规管理。观察组采用FMEA联合PDCA管理。对比2组一般资料、风险优先数(risk priority number,RPN)值、1 h抗生素使用达标率、28 d病死率及医护人员合作满意度,分析影响1 h抗生素使用达标率的因素。结果患者一般资料、28 d病死率差异无统计学意义(P>0.05)。观察组感染性休克患者1 h抗生素使用达标率及医护合作满意度明显高于对照组,前5位失效模式的RPN值明显低于对照组,差异有统计学意义(P<0.05)。多因素分析结果显示,基础疾病(OR=0.585,95%CI:0.405~0.845,P<0.05)、抗生素使用级别(OR=0.272,95%CI:0.134~0.551,P<0.05)、患者家属教育程度(OR=2.484,95%CI:1.100~5.611,P<0.05)是影响1 h内抗生素使用达标率的独立危险因素。结论FMEA联合PDCA管理工具可规范感染性休克患者1 h抗生素使用流程,提高1 h抗生素使用达标率,加强医护合作。

中药抗休克合剂对严重烫伤大鼠早期肠损伤的影响

目的观察在高渗盐溶液(HS)补液基础上应用中药抗休克合剂对严重烫伤大鼠早期肠损伤的影响。方法选取32只8周龄SD大鼠,按照随机数表法将其随机分为假伤组、LR组、HS600组、HS600+中药组,每组8只。假伤组大鼠建立假伤模型以及LR组、HS600组、HS600+中药组大鼠建立烫伤模型后,LR组大鼠采用乳酸钠林格注射液(LR)补液,HS600组大鼠采用600 mmol/L HS补液,HS600+中药组大鼠采用600 mmol/L HS补液+中药抗休克合剂灌胃。对比观察模型建立24 h后各组大鼠血Na^(+)浓度,血清炎症因子水平以及小肠组织氧化应激水平与p38丝裂原活化蛋白激酶(p38MAPK)通路活化程度。结果LR组大鼠血Na^(+)浓度明显低于假伤组、HS600组及HS600+中药组(q=14910、32211、30010,P均<0001),且HS600组与HS600+中药组无明显差异(q=2198,P=0130)。LR组、HS600组及HS600+中药组大鼠血清肿瘤坏死因子-α、白细胞介素-10、白细胞介素-18水平以及小肠组织中丙二醛水平和磷酸化p38MAPK与p38MAPK比值均明显高于假伤组(肿瘤坏死因子-α:q=16070、10810、7579,P均<0001;白细胞介素-10:q=15920、20210、23850,P均<0001;白细胞介素-18:q=12750、7562、3897,P<0001、P<0001、P=0049;丙二醛:q=28450、20320、10160,P均<0001;磷酸化p38MAPK与p38MAPK比值:q=54310、15090、9196,P均<0001),且HS600+中药组大鼠血清肿瘤坏死因子-α与白细胞介素-18水平以及小肠组织中丙二醛水平和磷酸化p38MAPK与p38MAPK比值均明显低于LR组与HS600组、白细胞介素-10水平明显高于LR组与HS600组(肿瘤坏死因子-α:q=8494、3932,P<0001、P=0048;白细胞介素-18:q=9357、4165,P<0001、P=0031;丙二醛:q=18290、10160,P均<0001;磷酸化p38MAPK与p38MAPK比值:q=45110、5899,P<0001、P=0001;白细胞介素-10:q=7929、3939,P<0001、P=0047)。LR组、HS600组及HS600+中药组大鼠小肠组织中超氧化物歧化酶水平均明显低于假伤组(q=20880、14120、11110,P均<0001),且HS600+中药组明显高于LR组与HS600组(q=9772、4008,P<0001、P=0043)。结论与单独应用LR或HS补液相比,在HS补液基础上加用中药抗休克合剂可有效降低严重烫伤大鼠机体炎症反应及氧化应激反应程度、抑制p38MAPK通路过度活化,从而减轻早期肠损伤。

双变频切换在炼化企业风机类负载中的应用

炼化企业变频调节风机类负载是装置的重要设备之一。为了解决变频器本体故障、电力系统波动等因素导致的设备停机事故,提出了双变频器切换的抗晃电方案。在实施过程中,从设备选型、参数优化、简化接线方式等方面进行改造。通过改造后的试验结果分析表明,该方案满足了工艺需求,提高了炼化企业重要变频风机类负载的运行可靠性。

变频器抗晃电的直流支撑技术研究

随着现代社会的蓬勃发展,人们的生活与社会生产都需要使用大量电能。尤其是化工、冶金等连续型生产企业,在其生产过程中要求供电不中断,为生产活动的工艺流程提供持续不断的电流。变频器在工业生产中具有重要作用,能够通过调节电源频率来控制机械设备的速度,满足生产过程中对不同设备的调速需求。系统电压的短时波动将导致变频器失压停机,进而造成整条生产线停机,给生产企业造成了严重的经济损失,因此强化变频器抗晃电具有一定的现实意义。通过动能缓冲技术、直流支撑技术来实现变频器的抗晃电,能够为企业的生产活动提供稳定电流,保障电力设备的安全性,有助于提高生产企业的经济效益。通过分析变频器抗晃电的直流支撑技术路线,研究Boost技术、高频变压技术以及晶闸管技术等抗晃电技术方案的使用原理及其优缺点。

一种数值稳定的低耗散激波捕捉格式

HLLC格式应用广泛且可以准确捕捉激波间断,其满足熵条件和保正性,易于推广到其他双曲系统。但是,在计算多维强激波时出现的数值不稳定现象大大限制了它在高马赫数流动问题中的应用。本文基于三维无黏可压缩欧拉方程组构造一种激波数值稳定的HLLC格式(SS-HLLC):将传统的HLLC通量显式地改写成耗散的HLL通量和反扩散项的形式,利用充分光滑的控制函数调节激波附近横向通量中的反扩散项来改善格式的激波数值稳定性,分析证明了反扩散控制技术的有效性。此外,采用简单的THINC重构方法和BVD算法来减少数值耗散项中的密度差,从而构造了一种低耗散的激波数值稳定格式(LD-SS-HLLC),可进一步提高格式对接触间断的分辨率。经过一系列标准算例测试,结果证明了LD-SS-HLLC格式的低耗散性和激波数值稳定性。

某户外电炉防触电可靠性验证方案研究

本文论述了户外电烤炉在消费者操作过程中可能会存在漏电风险,本文根据可靠性管理办法,运用不同环境应力筛选,对其整机系统防触电可靠性进行研究,并提出验证方案,有效识别和关闭其触电风险,提高产品安全性,为后面的户外电炉产品防触电可靠性验证方案提供了方向和措施依据。

强震下城铁高架简支梁桥合理减隔震措施研究

城际铁路(城铁)高架桥是城市交通中的核心枢纽工程。目前对于城铁桥梁抗震设计更多仍是借鉴公路桥梁延性抗震为主,然而规范中城铁桥墩最小体积配箍率和高铁桥墩一致,比公路桥墩的最小体积配箍率要小25%。因此,有必要借鉴高铁桥梁减隔震设计原则,研究城铁桥梁的合理减隔震体系。以某城铁高架三跨32.7m标准跨径简支梁桥为研究对象,首先,提出强震区多种减隔震布置措施,研究各布置措施的本构模型,进而基于OpenSees建立三维城铁高架桥梁弹塑性模型,并对其进行验证;其次,对比分析强震下城铁高架桥梁的多种减隔震措施的减震效果,并提出最优减隔震体系。研究结果表明:强震下球形钢支座、摩擦摆支座均可降低墩底内力和墩顶位移,但无法限制墩梁间相对位移,易落梁,需配合限位装置共同使用,以限制上部结构出现过大的地震位移及缓解强震区竖向地震动作用。采用“球形钢支座+减震卡榫”和“摩擦摆支座+减震卡榫”均可有效限制墩梁间的相对位移,但“球形钢支座+减震卡榫”对墩底内力和墩顶位移的减震效果较差。因此,建议采用“摩擦摆支座+减震卡榫”作为强震区城铁高架桥梁的最优减隔震体系。

基于防跳继电器引发全站失电的分析

当前,高压开关柜的防跳继电器通常采用电磁式继电器,当高压开关柜震动时,继电器的触点易被导通,引起断路器误跳闸,导致设备停电。对此,文章基于防跳继电器的结构、原理等角度对其引发的全站失电事件进行分析。针对常规防跳继电器易误跳的问题,利用微机综保自身的触点,配合必要的逻辑编程解决该问题。该方法可替换常规的继电器,避免因震动造成开关误动作跳闸,同时又可实现开关的防跳跃功能。

基于三维负泊松比蜂窝结构的防冲支架性能研究

提出一种应用于支架顶梁上方的吸能缓冲装置,该缓冲装置采用轻质、吸能量高的负泊松比材料,旨在将冲击地压带来的能量快速让位、缓冲吸收。对缓冲装置的构型进行设计并进行准静态压缩仿真;对缓冲装置施加低速、中速、高速进行抗冲击特性研究。结果表明:胞元角度为θ=70°的胞元具有良好的负泊松比效应、更长的压缩行程、更高的吸能量,适宜于做缓冲结构的胞元结构。对缓冲结构施加不同的速度,得到随着冲击速度的增大,缓冲结构的比吸能越大。

舰艇管路系统的抗冲击性能弹性评估方法

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