摆动工艺参数对铝合金激光焊焊接质量的影响

为了研究铝合金激光焊接过程中摆动参数对焊接结果的影响,文章采用单因素的变量试验,在其他参数固定为功率4 kW、焊接速度80 mm/s、离焦量0的情况下,分别分析激光摆动频率、摆动幅度等参数对2 mm厚的6k21和5754铝合金薄板焊缝成型、焊接质量的影响。试验结果表明:随着摆动幅度的增加,焊缝熔深减小,熔宽先增加后减小;随着摆动频率的增加,熔深、熔宽均减小;在焊缝没有焊接缺陷的情况下,试件的剪切力与熔宽成正相关。文章研究结果可为汽车轻量化全铝车身连接中的激光焊接工艺提供一定的理论参考。

胱抑素C冰冻人血清国家标准品的建立及溯源性研究

目的:对胱抑素C进行量值溯源性研究,研制胱抑素C冰冻人血清国家标准品,建立用于胱抑素C检测试剂盒准确度评价的质量评价标准,提升检验检测水平。方法:以人血清样本为原料进行无菌分装、制备胱抑素C冰冻人血清国家标准品,采用多实验室联合赋值的方法对胱抑素C国家标准品候选品进行赋值、标定,建立可溯源至国际标准物质ERM-DA471/IFCC的溯源链,并采用免疫比浊的方法对其均匀性、稳定性进行验证。结果:建立了包含2个水平量值的胱抑素C冰冻人血清国家标准品,水平1为(0.94±0.03)mg·L^(-1)(k=2),水平2为(3.52±0.09)mg·L^(-1)(k=2)。该国家标准品均匀性和稳定性良好。30天短期稳定性研究结果显示,室温条件下,国家标准品(水平1和水平2)可稳定5天;2~8℃条件下,水平1可稳定10天,水平2可稳定20天;-20℃条件下,水平1和水平2均至少可稳定30天。溯源准确性采用血清参考盘和临床血清样本进行验证,研究结果显示,该国家标准品和国际标准品ERM-DA471/IFCC具有良好的溯源性。结论:通过对胱抑素C进行量值溯源性研究,研制出胱抑素C冰冻人血清国家标准品(360046-202001),并获得批准向社会提供,可用于人血清中胱抑素C检测试剂盒正确度评价及临床实验室检测系统量值准确性评价。

基于响应面法的铝合金角接激光焊工艺优化

文章选用板材厚度为2 mm的5754铝合金,采用角接的搭接形式,开展激光熔焊焊接试验。以激光功率P、焊接速度v、离焦量Z为试验参数,以焊接接头的最大拉力F为响应指标,建立响应面分析的数学模型。研究结果表明:激光功率、焊接速度、离焦量对最大拉力均有明显影响。激光功率越大、焊接速度和离焦量越小,最大拉力越大。分析所建立的数学模型,确定较优工艺区间,结合焊缝成形的宏观形貌,获取最优工艺参数组合。最大拉力相比于试验组中的最优组提升5.55%。

密闭空间内高压过冷水射流冲击高温铅铋熔池能质传输数值模拟研究

蒸汽发生器传热管破裂(SGTR)事故是铅铋冷却快堆(LFR)最为严重的设计基准事故之一,将导致二回路高压过冷水通过管道破口高速射流注入一回路高温液态铅铋(LBE),强烈的相间热质传输可能引发蒸汽爆炸,严重威胁堆芯结构的完整性。为了揭示SGTR事故现象机理,本文基于VOF多相流模型、LES湍流模型和Lee相变模型,考虑容器内覆盖气体层作用,建立了密闭空间内高压过冷水射流冲击高温LBE多相流动与瞬态传热传质过程的三维数值计算模型,重点分析了过冷水温度及入口压力对射流发展和射流周围环境(即覆盖气体层和LBE区域)的影响。结果表明,典型的射流按相态可分为4个区域,即水-蒸汽过渡区、多相流区、末端水相区和蒸汽斑块区。射流沸腾主要发生在射流中心区域和两侧的相界面上,相变产生的蒸汽夹带残余水相沿着界面从射流的末端向顶部迁移,计算工况下最大沸腾速率通常在喷管出口处,为7090 kg/(m^(3)·s)。覆盖气体层和LBE区压力与过冷水温度和入口压力均呈正相关,LBE区压力会随着射流发展逐渐增加,同时蒸汽的迁移可能引起LBE区压力发生波动,在4.4 ms时间内在覆盖气体层和LBE区获得的最大压力分别为0.157 MPa和0.351 MPa。本文结果揭示了射流沸腾机理与压力演化特性,为铅铋冷却快堆SGTR事故系统安全评估提供了理论支撑。

基于热藏-井筒-地面一体化的地热田智能开发研究与实践

地热能开发利用对于优化能源结构、实现碳达峰、碳中和目标具有重要意义。按照总体规划、逐步实施、突出重点的思路,进行了智能地热田整体架构设计,并结合地热供暖业务开展了实践,整体架构为“一个中心、两个平台”,即数据资源中心、地热余热生产指挥平台、地下地面一体化协同应用平台,以地质热藏、地热井筒作为地热资源开发的地面边界条件,建立基于IAM(综合资产模型)技术的地质热藏-井筒-地面一体化耦合模型,结合机器学习等技术初步实现了地热供热智能辅助决策,支撑预测预警、平稳开发、智能运维、安全生产。该技术方案在地热田开发优化调整、管网及换热站内工艺设备优化、智能供热运维等方面得到了应用,整体架构设计符合信息技术发展方向,对于地热资源智能开发具有参考价值。

窒息氧合在临床麻醉中的研究进展

窒息氧合是指患者在没有自主呼吸或机械正压通气的情况下血液从肺部摄取氧气维持氧合。在全麻实施过程中,诱导后自主呼吸停止而安全的气道未建立之前,使用窒息氧合能在预充氧的基础上延长患者的安全呼吸暂停时间,从而减少气管插管的尝试次数,降低气道损伤以及低氧血症、血流动力学失代偿的发生率。近十年来,越来越多的窒息氧合技术已经被应用于不同的临床环境中,如围术期的气道管理和“无管麻醉”等。为进一步加深对窒息氧合的认识和了解其应用范围,本文根据现有关于窒息氧合机制、方法及临床应用的最新研究进行综述,为临床应用提供参考。

超声处理对Al-2Sn合金凝固组织及除气效果的影响

研究了超声处理对Al-2Sn合金凝固组织及除气的影响,除气效果用密度法来表征。结果表明,超声处理对铸锭凝固组织的细化和除气有极佳的效果。使用2000 W超声功率处理30 s的晶粒细化效果最好,铸锭断面组织主要为等轴晶;使用2000 W超声处理60 s具有最佳的除气效果,此时铸锭的密度和除气率最高,分别为2.7224 g/cm^(3)和67%。最后对高强超声的细化和除气机理也进行了分析。

Passive activity enhances residual control ability in patients with complete spinal cord injury

Patients with complete spinal cord injury retain the potential for volitional muscle activity in muscles located below the spinal injury level.However,because of prolonged inactivity,initial attempts to activate these muscles may not effectively engage any of the remaining neurons in the descending pathway.A previous study unexpectedly found that a brief clinical round of passive activity significantly increased volitional muscle activation,as measured by surface electromyography.In this study,we further explored the effect of passive activity on surface electromyographic signals during volitional control tasks among individuals with complete spinal cord injury.Eleven patients with chronic complete thoracic spinal cord injury were recruited.Surface electromyography data from eight major leg muscles were acquired and compared before and after the passive activity protocol.The results indicated that the passive activity led to an increased number of activated volitional muscles and an increased frequency of activation.Although the cumulative root mean square of surface electromyography amplitude for volitional control of movement showed a slight increase after passive activity,the difference was not statistically significant.These findings suggest that brief passive activity may enhance the ability to initiate volitional muscle activity during surface electromyography tasks and underscore the potential of passive activity for improving residual motor control among patients with motor complete spinal cord injury.

Voluntary wheel running ameliorated the deleterious effects of high-fat diet on glucose metabolism,gut microbiota and microbial-associated metabolites

Exercise training is critical for the early prevention and treatment of obesity and diabetes mellitus.However,the mechanism with gut microbiota and fecal metabolites underlying the effects of voluntary wheel running on high-fat diet induced abnormal glucose metabolism has not been fully elaborated.C57BL/6 male mice were randomly assigned to 4 groups according to diets(fed with normal chow diet or high-fat diet)and running paradigm(housed in static cage or with voluntary running wheel).An integrative 16S rDNA sequencing and metabolites profiling was synchronously performed to characterize the effects of voluntary wheel running on gut microbiota and metabolites.It showed that voluntary wheel running prevented the detrimental effects of high-fat feeding on glucose metabolism 16S rDNA sequencing showed remarkable changes in Rikenella and Marvinbryantia genera.Metabolic profiling indicated multiple altered metabolites,which were enriched in secondary bile acid biosynthesis signaling.In conclusion,our study indicated that voluntary wheel running significantly improved glucose metabolism and counteracted the deleterious effects of high-fat feeding on body weight and glucose intolerance.We further found that voluntary wheel running could integratively program gut microbiota composition and fecal metabolites changes,and may regulate muricholic acid metabolism and secondary bile acid biosynthesis in high-fat fed mice.

Cu Stress-Induced Transcriptome Alterations in Sorghum and Expression Analysis of the Transcription Factor-Encoding Gene SbWRKY24

Sorghum is not only an important bio-energy crop but also a vital raw material for brewing.Exogenous copper affects the growth and metabolism of crops in specific ways.This study identified 8475 differentially expressed genes(DEGs)by high-throughput transcriptome sequencing in the sorghum cultivar‘Jinnuoliang 2’after 24 h of treatment with 10 mM CuSO4.Using GO analysis,476 genes were functionally annotated,which were mainly related to catabolism and biosynthetic processes.Additionally,90 pathways were annotated by employing the KEGG analysis.Among them,glutathione metabolism and peroxisome were induced,while photosynthesis,photosynthesis-antenna protein,and carbon sequestration of photosynthetic organisms were inhibited.Of the DEGs,399 were identified to encode transcription factors belonging to 49 families.This study also identified a WRKY transcription factor-encoding gene SbWRKY24 from the transcriptome data.For studying its function,the relative expression levels of SbWRKY24 in roots and leaves post-treatment with different growth hormones and exposure to a variety of abiotic stresses were detected by RT-qPCR.SbWRKY24 showed treatment-and tis-sue-specific expression patterns,indicating its unique role in stress tolerance.This study lays a theoretical basis for the functional exploration of SbWRKY24,elucidating the mechanism of copper resistance,and elaborating on the stress responses in sorghum.It also guides the exploration of the molecular mechanism of copper ions inducing intracellular signal transduction pathways.

The dynamic characteristics of saturated remolded loess under cyclic load

Due to the joint development characteristic and macropore structure of loess,it is easy to cause structure collapse under earthquake or artificial vibration.The study on the loess disaster effect and its mechanism under earthquake action is insufficient due to its complexity.Hence,to study the deformation and mechanical properties more accurately,the dynamic characteristics of saturated remolded loess under cyclic dynamic load were tested using a GDS dynamic triaxial instrument in this paper.The test results show that strain and pore water pressure increase gradually at different rates with the development of vibration,and there is an obvious inflection point in the time-history curve of both.When the number of vibrations(N)exceeds this point,the strain increases rapidly,and pore water pressure tends to be stable.Under the action of large amplitude and low-frequency dynamic load,the strain and pore water pressure increase rapidly with fewer vibrations and the deviator stress(q)decreases rapidly,while the sample achieves damage faster with the increase of amplitude.During the application of a dynamic load,the effective stress(p)gradually decreases and its rate of change slows down.Finally,when the saturated remolded loess is subjected to a constant-amplitude dynamic load,the combination of large amplitude and low frequency leads to the failure of the sample in the shortest time.

Icariin accelerates bone regeneration by inducing osteogenesisangiogenesis coupling in rats with type 1 diabetes mellitus

BACKGROUND Icariin(ICA),a natural flavonoid compound monomer,has multiple pharmacological activities.However,its effect on bone defect in the context of type 1 diabetes mellitus(T1DM)has not yet been examined.AIM To explore the role and potential mechanism of ICA on bone defect in the context of T1DM.METHODS The effects of ICA on osteogenesis and angiogenesis were evaluated by alkaline phosphatase staining,alizarin red S staining,quantitative real-time polymerase chain reaction,Western blot,and immunofluorescence.Angiogenesis-related assays were conducted to investigate the relationship between osteogenesis and angiogenesis.A bone defect model was established in T1DM rats.The model rats were then treated with ICA or placebo and micron-scale computed tomography,histomorphometry,histology,and sequential fluorescent labeling were used to evaluate the effect of ICA on bone formation in the defect area.RESULTS ICA promoted bone marrow mesenchymal stem cell(BMSC)proliferation and osteogenic differentiation.The ICA treated-BMSCs showed higher expression levels of osteogenesis-related markers(alkaline phosphatase and osteocalcin)and angiogenesis-related markers(vascular endothelial growth factor A and platelet endothelial cell adhesion molecule 1)compared to the untreated group.ICA was also found to induce osteogenesis-angiogenesis coupling of BMSCs.In the bone defect model T1DM rats,ICA facilitated bone formation and CD31hiEMCNhi type H-positive capillary formation.Lastly,ICA effectively accelerated the rate of bone formation in the defect area.CONCLUSION ICA was able to accelerate bone regeneration in a T1DM rat model by inducing osteogenesis-angiogenesis coupling of BMSCs.

反向挤压对Mg-1Bi-0.5Gd合金耐蚀性的影响

镁合金因其密度低、比强度高等优点,在航空航天、汽车工业和电子产品中得到广泛应用。然而,镁合金的耐蚀性能较差,限制了其应用。为改善镁合金的耐蚀性,本文采用Bi和Gd元素进行合金化处理,并通过反向挤压工艺制备了Mg-1Bi-0.5Gd(0.94%Bi,0.53%Gd,质量分数)合金。通过XRD、OM、SEM、析氢实验和电化学测试,研究了挤压前后Mg-1Bi-0.5Gd合金的微观组织和腐蚀行为的变化。结果表明,与均匀态合金相比,挤压态Mg-1Bi-0.5Gd合金表现出更高的腐蚀电位和更低的腐蚀电流密度,显示出更优异的耐蚀性。这是由于挤压工艺细化了合金的晶粒组织,显著提升了耐蚀性能。

Zn对挤压态Mg-3Sn-1Ca合金耐蚀性的影响

目的 提高挤压态Mg-3Sn-1Ca合金的耐腐蚀性能。方法 通过合金熔炼制备了Mg-3Sn-Ca(TX31)和Mg-3Sn-Ca-Zn(TXZ311)两种挤压态合金,利用XRD、金相、SEM、EDS、EBSD、析氢、电化学极化曲线和阻抗谱,分析了TX31和TXZ311两种合金的微观组织及耐腐蚀性能。结果 XRD和EDS结果表明,挤压态TX31和TXZ311两种合金中第二相均为CaMgSn相,TXZ311合金中由于Zn的添加,CaMgSn相增加且分布更加均匀。金相和EBSD结果表明,Zn的添加可以提高TX31合金的动态再结晶程度和{0002}基面织构强度,改善TX31合金中组织的不均匀性。从极化曲线上可得,腐蚀电位和腐蚀电流分别为-1.57V和6.95×10^(-5)A。添加Zn后,腐蚀电位升高(-1.49 V),腐蚀电流减小(1.02×10^(-5)A),表明合金耐蚀性提高。对比两种合金阻抗谱可发现,TXZ311合金具有比TX31合金更大的容抗弧,表明其表面的电荷转移电阻和表面膜的电阻最高,动态腐蚀过程中氧化产物膜具有较好的稳定性,有效阻碍了α-Mg基体的腐蚀。TX31合金析氢量和时间成正比,腐蚀速率为3.7mm/a。而TXZ311合金腐蚀速率仅为1.6mm/a,析氢量在腐蚀12 h后明显降低,表明合金表面形成了可以阻碍腐蚀进行的氧化膜。结论 Zn元素可以极大提高TX31合金的耐蚀性。这是由于添加Zn元素后,TXZ311合金腐蚀膜层间的黏附力增加,动态再结晶程度增高,晶粒组织更加均匀,{0001}基面织构强度增加。因此,TXZ311合金的耐蚀性远高于TX31合金。

抗生素风险管理体系构建策略

抗生素在给人们带来临床价值的同时也带来风险:耐药菌株的不断出现,神经毒性、肾衰竭、心脏疾病、哮喘等各种不良反应发生。我们可以采取措施来控制抗生素使用风险,建立抗生素使用的量化指标进行定量控制,通过处方系统对抗生素的使用进行监控,依靠药师来监督医生的处方行为,另外还可以对患者进行抗生素使用的教育,使其对潜在的风险有所认识。

Stromal cell-derived factor-1α regulates chondrogenic differentiation via activation of the Wnt/β-catenin pathway in mesenchymal stem cells

BACKGROUND Mesenchymal stem cells(MSCs)have been applied to treat degenerative articular diseases,and stromal cell-derived factor-1α(SDF-1α)may enhance their therapeutic efficacy.However,the regulatory effects of SDF-1αon cartilage differentiation remain largely unknown.Identifying the specific regulatory effects of SDF-1αon MSCs will provide a useful target for the treatment of degenerative articular diseases.AIM To explore the role and mechanism of SDF-1αin cartilage differentiation of MSCs and primary chondrocytes.METHODS The expression level of C-X-C chemokine receptor 4(CXCR4)in MSCs was assessed by immunofluorescence.MSCs treated with SDF-1αwere stained for alkaline phosphatase(ALP)and with Alcian blue to observe differentiation.Western blot analysis was used to examine the expression of SRY-box transcription factor 9,aggrecan,collagen II,runt-related transcription factor 2,collagen X,and matrix metalloproteinase(MMP)13 in untreated MSCs,of aggrecan,collagen II,collagen X,and MMP13 in SDF-1α-treated primary chondrocytes,of glycogen synthase kinase 3β(GSK3β)p-GSK3βandβ-catenin expression in SDF-1α-treated MSCs,and of aggrecan,collagen X,and MMP13 in SDF-1α-treated MSCs in the presence or absence of ICG-001(SDF-1αinhibitor).RESULTS Immunofluorescence showed CXCR4 expression in the membranes of MSCs.ALP stain was intensified in MSCs treated with SDF-1αfor 14 d.The SDF-1αtreatment promoted expression of collagen X and MMP13 during cartilage differentiation,whereas it had no effect on the expression of collagen II or aggrecan nor on the formation of cartilage matrix in MSCs.Further,those SDF-1α-mediated effects on MSCs were validated in primary chondrocytes.SDF-1αpromoted the expression of p-GSK3βandβ-catenin in MSCs.And,finally,inhibition of this pathway by ICG-001(5μmol/L)neutralized the SDF-1α-mediated up-regulation of collagen X and MMP13 expression in MSCs.CONCLUSION SDF-1αmay promote hypertrophic cartilage differentiation in MSCs by activating the Wnt/β-catenin pathway.These findings provide further evidence for the use of MSCs and SDF-1αin the treatment of cartilage degeneration and osteoarthritis.

储热材料技术性能与适用范围研究

储热技术的开发和利用在提高能源转换和利用、解决可再生能源方面起着至关重要的作用,当前的关注热点极高。文章通过对储热技术的研究进展,对相变储热材料、显热储热材料、热化学储热材料三大类储热材料从技术性能、适用范围及应用情况方面进行了概述。指出了各种不同形式储热材料的优劣性,将其覆盖到不同温度范围、不同储能规模的能量储存领域,为能源系统提供多种解决方案,为新型储热系统的研究、应用及发展提供参考。

文物贴金用传统金胶漆耐湿污染大气腐蚀性能的研究

根据重庆大足所处的酸雨雾环境条件,采用多种模拟加速老化试验,并结合红外光谱、接触角和形貌观察等分析手段,研究了文物贴金用传统金胶漆耐湿污染大气腐蚀的情况。结果表明:大气酸雨污染加速了水的干湿交替环境对金胶漆的影响。光照、湿度和污染大气的干湿交替环境对金胶漆都有不同程度的影响,其中污染大气的干湿交替环境对金胶漆的耐老化性能破坏最严重,最终导致了金胶漆材料的腐蚀破坏。

城市区域综合交通安全管理评估方法研究

为营造交通行业安全生态,助力城市安全发展,在对大量交通运输企业开展安全生产千分制评价分析的基础上,构建包括千分制评价结果、区域事故特征、行业监管情况3个一级指标,15个二级指标的区域交通运输安全管理综合评估指标体系,依托结构熵权法计算各级指标权重,引入同行业权重,构建了安全管理现状评估模型,并选取具体行政区域开展方法应用,研究表明评估结果与区域现实交通运输安全管理现状吻合,研究成果对城市区域交通安全风险的准确把握、精准管控、源头治理及动态管理具有重要现实和理论意义.

液相色谱-氢化物发生原子荧光光谱法测定饲料中砷的形态

建立了饲料中亚砷酸盐(As^(3+))、砷酸盐(As^(5+))、一甲基砷酸(MMA)、二甲基砷酸(DMA)、对氨基苯胂酸(p-ASA)、羟基苯胂酸(4-OH)和洛克沙胂(ROX)共7种不同形态砷的高效液相色谱-氢化物发生原子荧光光谱(HPLC-HG-AFS)分析方法。饲料样品采用甲醇-水(1∶1,V/V)溶液提取,15 mmol/L(NH_4)_2HPO_4和10 mmol/L邻苯二甲酸氢钾为流动相,经PRP-X100阴离子交换色谱柱分离后,由HG-AFS测定。结果表明,7种砷形态标准曲线的线性关系良好(R2≥0.9964),方法检出限为5~30 μg/kg,平均回收率为76.3%~108.1%,日内相对标准偏差≤7.7%,日间相对标准偏差≤17.4%。本方法灵敏度高、前处理简单、运行费用低廉,适用于饲料产品中砷的形态分析。