新型二维声子晶体带隙特性及调控方法研究

为拓宽声子晶体弹性波带隙,提出一种关于基体双侧对称的声子晶体结构模型.采用有限元法计算了该声子晶体的能带结构和本征模态,基于局域共振机理深入分析了其带隙的形成机理,通过改变几何参数及施加等轴预拉伸应变的方法对该声子晶体的带隙进行被动调控与主动调控.仿真结果表明:所提声子晶体结构基体中的长波行波与振子的谐振相互耦合作用产生一条局域共振带隙,通过优化几何参数可以获得起始频率更低的宽频带隙,对结构施加等轴预拉伸应变可以有效拓宽带隙且带隙宽度随着预拉伸应变的增大而变宽.研究结果为声子晶体的带隙主动调控提供了方案,为结构减振降噪提供了新思路.

PI3K/AKT signaling and neuroprotection in ischemic stroke:molecular mechanisms and therapeutic perspectives

It has been reported that the PI3K/AKT signaling pathway plays a key role in the pathogenesis of ischemic stroke.As a result,the development of drugs targeting the PI3K/AKT signaling pathway has attracted increasing attention from researchers.This article reviews the pathological mechanisms and advancements in research related to the signaling pathways in ischemic stroke,with a focus on the PI3K/AKT signaling pathway.The key findings include the following:(1)The complex pathological mechanisms of ischemic stroke can be categorized into five major types:excitatory amino acid toxicity,Ca^(2+)overload,inflammatory response,oxidative stress,and apoptosis.(2)The PI3K/AKT-mediated signaling pathway is closely associated with the occurrence and progression of ischemic stroke,which primarily involves the NF-κB,NRF2,BCL-2,mTOR,and endothelial NOS signaling pathways.(3)Natural products,including flavonoids,quinones,alkaloids,phenylpropanoids,phenols,terpenoids,and iridoids,show great potential as candidate substances for the development of innovative anti-stroke medications.(4)Recently,novel therapeutic techniques,such as electroacupuncture and mesenchymal stem cell therapy,have demonstrated the potential to improve stroke outcomes by activating the PI3K/AKT signaling pathway,providing new possibilities for the treatment and rehabilitation of patients with ischemic stroke.Future investigations should focus on the direct regulatory mechanisms of drugs targeting the PI3K/AKT signaling pathway and their clinical translation to develop innovative treatment strategies for ischemic stroke.

Tranylcypromine upregulates Sestrin 2 expression to ameliorate NLRP3-related noise-induced hearing loss

Noise-induced hearing loss is the primary non-genetic factor contributing to auditory dysfunction.However,there are currently no effective pharmacological interventions for patients with noise-induced hearing loss.Here,we present evidence suggesting that the lysine-specific demethylase 1 inhibitor–tranylcypromine is an otoprotective agent that could be used to treat noise-induced hearing loss,and elucidate its underlying regulatory mechanisms.We established a mouse model of permanent threshold shift hearing loss by exposing the mice to white broadband noise at a sound pressure level of 120 d B for 4 hours.We found that tranylcypromine treatment led to the upregulation of Sestrin2(SESN2)and activation of the autophagy markers light chain 3B and lysosome-associated membrane glycoprotein 1 in the cochleae of mice treated with tranylcypromine.The noise exposure group treated with tranylcypromine showed significantly lower average auditory brainstem response hearing thresholds at click,4,8,and 16 k Hz frequencies compared with the noise exposure group treated with saline.These findings indicate that tranylcypromine treatment resulted in increased SESN2,light chain 3B,and lysosome-associated membrane glycoprotein 1 expression after noise exposure,leading to a reduction in levels of 4-hydroxynonenal and cleaved caspase-3,thereby reducing noise-induced hair cell loss.Additionally,immunoblot analysis demonstrated that treatment with tranylcypromine upregulated SESN2 expression via the autophagy pathway.Tranylcypromine treatment also reduced the production of NOD-like receptor family pyrin domaincontaining 3(NLRP3)production.In conclusion,our results showed that tranylcypromine treatment ameliorated cochlear inflammation by promoting the expression of SESN2,which induced autophagy,thereby restricting NLRP3-related inflammasome signaling,alleviating cochlear hair cell loss,and protecting hearing function.These findings suggest that inhibiting lysine-specific demethylase 1 is a potential therapeutic strategy for preventing hair cell loss and noise-induced hearing loss.

Synchronization Characterization of DC Microgrid Converter Output Voltage and Improved Adaptive Synchronization Control Methods

This paper deeply introduces a brand-new research method for the synchronous characteristics of DC microgrid bus voltage and an improved synchronous control strategy.This method mainly targets the problem of bus voltage oscillation caused by the bifurcation behavior of DC microgrid converters.Firstly,the article elaborately establishes a mathematical model of a single distributed power source with hierarchical control.On this basis,a smallworld network model that can better adapt to the topology structure of DC microgrids is further constructed.Then,a voltage synchronization analysis method based on the main stability function is proposed,and the synchronous characteristics of DC bus voltage are deeply studied by analyzing the size of the minimum non-zero eigenvalue.In view of the situation that the line coupling strength between distributed power sources is insufficient to achieve bus voltage synchronization,this paper innovatively proposes a new improved adaptive controller to effectively control voltage synchronization.And the convergence of the designed controller is strictly proved by using Lyapunov’s stability theorem.Finally,the effectiveness and feasibility of the designed controller in this paper are fully verified through detailed simulation experiments.After comparative analysis with the traditional adaptive controller,it is found that the newly designed controller can make the bus voltages of each distributed power source achieve synchronization more quickly,and is significantly superior to the traditional adaptive controller in terms of anti-interference performance.

The spike weight contribution of the photosynthetic area above the upper internode in a winter wheat under different nitrogen and mulching regimes

Besides leaves, non-foliar green organs such as stem and spike are also considered photosynthetic organs. To assess the photosynthetic contributions of these organs, the correlations between these photosynthetic areas and single-spike weight were investigated in a winter wheat(Triticum aestivum L.) under four nitrogen and mulching treatments: N120,N150, N195, and N195 + M. Two-year repeated field experiments were conducted on the Loess Plateau of China. Non-foliar photosynthetic area, grain-filling ratio and duration,grain yield, and in particular, single-spike weight, were measured, recorded and analyzed.Under the N195 + M treatment, plants showed the largest area of photosynthetic organs(flag leaf and non-foliar organs) and the highest grain yield and single spike weight. Singlespike weight was positively correlated with the areas of all examined non-foliar photosynthetic organs, in particular with the area above the flag leaf node(R^2= 0.761*)and the area above the exposed part of the peduncle(EXP)(R^2= 0.800**). In addition, singlespike weight was highly correlated with average grain-filling ratio(R^2= 0.993**), whereas it was less highly correlated with grain-filling duration(R^2= 0.533). The morphological traits of non-foliar photosynthetic organs were also more highly correlated with average grainfilling ratio than with average grain-filling duration. The significant correlation between each of the morphological traits(area, length and width) of EXP and single-spike weight indicates that morphological traits of EXP are important in determining spike weight in the Loess Plateau environment.

Risk factors for Mallory-Weiss Tear during endoscopic submucosal dissection of superficial esophageal neoplasms

BACKGROUND Adverse events during endoscopic submucosal dissection(ESD)of superficial esophageal neoplasms,such as perforation and bleeding,have been welldocumented.However,the Mallory-Weiss Tear(MWT)during esophageal ESD remains under investigation.AIM To investigate the incidence and risk factors of the MWT during esophageal ESD.METHODS From June 2014 to July 2017,patients with superficial esophageal neoplasms who received ESD in our institution were retrospectively analyzed.The clinicopathological characteristics of the patients were collected.Patients were divided into an MWT group and non-MWT group based on whether MWT occurred during ESD.The incidence of MWTs was determined,and the risk factors for MWT were then further explored.RESULTS A total of 337 patients with 373 lesions treated by ESD were analyzed.Twenty patients developed MWTs during ESD(5.4%).Multivariate analysis identified that female sex(OR=5.36,95%CI:1.47-19.50,P=0.011)and procedure time longer than 88.5 min(OR=3.953,95%CI:1.497-10.417,P=0.005)were independent risk factors for an MWT during ESD.The cutoff value of the procedure time for an MWT was 88.5 min(sensitivity,65.0%;specificity,70.8%).Seven of the MWT patients received endoscopic hemostasis.All patients recovered satisfactorily without surgery for the laceration.CONCLUSION The incidence of MWTs during esophageal ESD was much higher than expected.Although most cases have a benign course,fatal conditions may occur.We recommend inspection of the stomach during and after the ESD procedure for timely management in cases of bleeding MWTs or even perforation outside of the procedure region.

微量元素对超大线能量EH36船板热影响区粗晶区组织和性能的影响

通过焊接热模拟研究了在超大线能量下焊接时Al元素、Mg元素和Ti元素含量对EH36高强船板钢热影响区粗晶区组织、性能的影响规律,采用Thermo-Calc热力学计算与SEM,EDS测试相结合的方法揭示了Al元素、Mg元素和Ti元素含量与母材中氧化物类型、尺寸、数量及粗晶区相变的关系.结果表明,Al_(2)O_(3)无法诱导针状铁素体相变,当Al元素质量分数低于0.005%时,钢中可形成Mg元素、Ti元素或其复合氧化物,可促进粗晶区针状铁素体相变.Mg元素和Ti元素联合添加时,当Mg元素质量分数由0.0042%降低为0.0013%,氧化物类型由MgO转变为Mg_(2)TiO_(4),经统计20个视场内的氧化物数量由408个提高到503个,平均直径由1.37μm减小到1.10μm,显著提高了非均匀形核的比表面积,抑制了晶界铁素体的形成,使t8/5=300 s时粗晶区热模拟试样-20℃冲击吸收能量由43 J提升到127 J.

Mendelian Randomization Study of Causal Relationship between Inflammatory Factors and Vascular Dementia and Chinese Herbal Medicines Screening for Prevention and Treatment

Objective: This study aims to examine the causal relationship between inflammatory factors and the probability of developing vascular dementia (VD) using Mendelian Randomization (MR) and Chinese herbal medicine prediction method, and to screen potential Chinese herbal medicines for the prevention and treatment of VD. Methods: Single nucleotide polymorphisms (SNPs) that exhibit a strong association with vascular dementia (VD) were identified as instrumental variables from the summary statistics of genome-wide association studies (GWAS). The primary analytical method employed was inverse variance weighting (IVW), while auxiliary analyses included the MR-Egger method, weighted median method, simple model, and weighted model. A two-way Mendelian randomization analysis was conducted to assess the causal relationship between inflammatory factors and the risk of VD, thereby identifying the key inflammatory factors involved. The MR-Egger intercept test and Cochran’s Q test were employed to assess the horizontal polymorphism and heterogeneity of instrumental variables. A sensitivity analysis was conducted by excluding one method at a time. Ultimately, based on key inflammatory factors, predictions for the prevention and treatment using traditional Chinese medicine were made, along with the screening of homologous herbal remedies. Results: Based on the results of the forward MR, the probability of developing VD was elevated when the inflammatory factors CXCL10 and CXCL5 were expressed at higher levels, whereas the probability of developing VD decreased as the expression levels of IL-13 and IL-20RA increased. These findings were supported by the assessment of pleiotropy, heterogeneity, and sensitivity. The results of the reverse MR analysis showed that there was no causal relationship between VD, as an exposure dataset, and these four inflammatory factors. According to the key inflammatory factors, 37 Chinese herbal medicines such as Siraitia grosvenorii were selected. Their characteristics including four natures, five flavors, channel tropism and treatment efficiency were cold, warm, neutral, pungent, sweet, bitter, lung meridian, spleen meridian, liver meridian, kidney meridian and clearing heat. Among them, Siraitia grosvenorii, Poria with hostwood, Perilla frutescens, and Radix Platycodi were all medicine and food homologous Chinese herbal medicines. Conclusions: The increase of CXCL10 and CXCL5 expression levels can increase the risk of VD, and the increase of IL-13 and IL-20 RA expression levels can reduce the risk of VD. Siraitia grosvenorii and other Chinese herbal medicines might be potential sources of therapeutic drugs for the treatment of VD. Medicine and food homologous Chinese herbal medicines, such as Siraitia grosvenorii, Poria with hostwood, Perilla frutescens, and Radix Platycodi, may help the elderly population with corresponding Traditional Chinese Medicine (TCM) constitutions to prevent VD.

沙漏型声子晶体的中低频隔声减振性能研究

针对机械工业装备上难以解决的低频振动与噪声问题,提出一种小尺寸、轻量化的新型声子晶体结构,研究其隔声减振特性,通过有限元仿真计算该声子晶体无限周期排列时的隔声量、能带结构以及有限周期排列时的振动响应,分析该结构的隔声机理及减振特性,并研究了关键几何参数、散射体材料和声波入射角度对该结构的隔声特性的影响规律,以及板结构减振频带的拓宽方法.结果表明:该声子晶体结构在1 000 Hz以下频率范围内具有优越的隔声减振性能,通过将不同参数的结构进行组合的方法可以拓宽声子晶体板的减振频带,为工程结构的中低频隔声减振及声子晶体的应用提供了新的思路与可行性参考.

突发事件中的嵌入式协同情报服务机制

[目的/意义]面对错综复杂的跨域突发事件时,必须破除情报资源、情报服务和应急管理内权责之间的壁垒,以产生嵌入式协同效应,从而提高应急管理效能。[方法/过程]文章从情报制度保障、情报组织保障及预警情报机制3个层面的视角出发,研究跨域情报服务突发事件的基础保障、情报缺失问题和实现路径。基于应急管理体系和传统情报协同服务体系,利用嵌入式协同情报监测采集系统和危机预警情报系统等工具,构建嵌入式协同情报服务体系框架。[结果/结论]情报理应成为突发事件应急管理的“冲锋号”。文章以嵌入式协同视角从3个层面提出变革情报支持范式:在法律法规层面凸显情报主导、提升情报组织保障和赋能、建立常态化危机预警情报机制。通过构建耦合联动的情报共同体,优化功能互补的应急管理工具箱,打造双重共轭的情报保障体系,从而形塑“随时待命、明辨真相、贴身决策”的嵌入式情报主导的突发事件应急管理情报服务机制。

X80管线钢焊缝区金属元素原位定量分析研究

X80高钢级管线钢是我国长距油气输送管线的主要用材,应用过程中发现不同厂家钢板焊后焊缝金属韧性差异较大,严重影响油气储运安全。迫切需要一种能对沿焊缝厚度方向的元素分布进行快速、准确原位定量分析的方法,帮助探索X80管线钢母材与焊材的共同作用对焊缝金属韧性的影响机理。提出一种用LA-ICP-MS法对钢材焊缝中Mn元素、Ni元素、Cr元素、Al元素及Nb元素进行原位定量分析的方法。通过优化激光脉冲频率20 Hz、激光能量100%(激光输出Imaged Aperture模式)、剥蚀孔径100μm及离焦距离0μm等提升质谱信号的强度及稳定性。实验采用基体匹配的标准样品进行校准,以基体元素^(57)Fe作为内标辅以校正。通过对相关质谱干扰进行分析,优选同位素^(27)Al、^(53)Cr、^(55)Mn、^(60)Ni及^(93)Nb。该方法线性相关系数达0.9927~0.9996,定量限0.23~2.57μg·g^(-1)。将建立的LA-ICP-MS微区原位定量分析方法应用于分析焊材相同而母材成分不同的2种X80管线钢焊缝中的元素含量分布。发现在两种母材中含量接近的Mn、Cr、Al、Nb元素在焊缝根部表现的稀释情况相当,而在两种母材中含量差异较大的Ni元素在距焊缝根部8.4 mm以内的含量差异显著。冲击试验结果显示,母材中Ni元素含量高的焊缝韧性相对明显高。对焊缝根部进行SEM分析,发现Ni元素含量提高利于生成板条状贝氏体组织。分析结果表明,X80管线钢中加入0.14%的Ni元素可减少母材对根部焊缝金属中Ni元素的稀释作用,较高的Ni元素含量通过促进低温板条贝氏体相变而提高焊缝冲击韧性。所建立的LA-ICP-MS原位定量分析方法对保障X80长输管线的安全运行有借鉴意义。

基于脉冲涡流监测与Wiener过程的再制造工作辊实时剩余寿命预测方法

再制造工作辊在热轧工作过程中熔覆层易发生复杂的退化行为,而其性能退化会影响轧制产品的质量。为实时监测轧辊退化情况并预测其剩余寿命,构建一套在线脉冲涡流监测方法和系统,采用变分模态分解-希尔伯特变换(VMD-Hilbert)方法提取0~5000 Hz频率边际谱能量和的增量作为轧辊退化特征。基于此,构造考虑个体差异的状态退化空间模型,结合最大期望(EM)算法和Kalman平滑滤波算法联合对模型中未知参数进行自适应参数估计,并利用层次分析法融合监测的历史数据与实时数据,以实现对再制造工作辊实时剩余寿命预测。实验结果表明,所提方法能够准确预测再制造工作辊剩余寿命,具有一定的应用前景。

基于激光图像特征提取的危险目标越界识别研究

为了提升危险目标越界激光识别准确性和效率,提出基于激光图像特征提取的危险目标越界识别研究。利用非线性直接变换方法完成激光点云反射图像转换的尺度不变特征点匹配;设计反锐化双掩模法图像增强结构,优化增强处理图像;对点云反射特征点展开沃尔什变换与融合,利用BP神经网络结构,识别越界的危险目标。实验结果表明,所提方法应用后图像特征细节信息得到增强,不存在局部曝光问题,对危险目标越界的错检率和漏检率最低,且具有较高的识别精度和识别效率。

大型实验室网络敏感数据访问认证方法仿真

由于大型实验室网络中的敏感数据认证过程繁琐复杂,且对其安全性要求较高,增加用户访问敏感数据的复杂性和时间成本。为此,提出一种大型实验室网络敏感数据访问多阶段认证算法。利用互补集合经验模态分解(Coplementary Ensemble Empirical Mode Decomposition,CEEMD),分解含有噪声的大型实验室网络数据,获取不同本征模态函数,通过改进小波阈值去噪,重构本征模态函数(Intrinsic Mode Functions,IMF)信息,获取降噪处理后的数据。通过Apriori算法和互信息理论,分析不同数据之间的相关性,挖掘其关联性,实现大型实验室网络敏感数据访问多阶段认证。通过仿真分析证实,采用所提算法可以精准完成大型实验室网络敏感数据访问多阶段认证,准确性在90%以上。

锅炉捕渣屏失效原因分析及预防措施

通过宏观特征、化学成分、力学性能分析,以及金相检验、硬度检测和电镜观察等技术手段,对捕渣屏水冷壁管爆管和断管失效原因进行分析。结果表明,锅炉炉顶落焦导致管道韧性断裂,产生断口。断口管与爆口管为同一水冷壁壁管,由于断口处工质泄漏,管道中的介质流量减少,导致管壁温度迅速上升,材料性能急剧下降,最终发生爆管。建议电厂在运行期间控制结焦,在检修期间加强对泄漏部位和水冷壁外敷设的耐热材料的检查,并及时修复脱落的耐热材料。

金融危机预警情报的失灵与治理

[研究目的]金融安全是国家安全的重要构成部分。金融危机预警作为金融监管的前哨和第一道防线,可将危机扼杀在摇篮中或将灾害损失降到最少。因此,探究金融危机预警情报服务框架,不仅为完善金融风险治理提供新的思路,还有助于提升情报服务金融安全的能力和水平。[研究方法]基于情报学视角,采用访谈和文献调查方法,对金融危机预警情报失灵的根源进行探析,构建了金融危机预警情报框架,并从预警原则、情报感知、分析策略和预警机制等方面进行阐释。[研究结论]研究表明,实施分级分解的分析战略、转变预警方式和强化危机预警机制等手段,有助于在不确定风险中提高危机管理响应效能,减少危机预警情报失灵的发生。

综合呼吸训练对老年帕金森病病人运动减少型构音障碍的影响

目的观察综合呼吸训练改善老年帕金森病病人运动减少型构音障碍的效果。方法将严格按照纳入、排除标准筛选的48例老年帕金森病病人随机分为对照组和治疗组,每组各24例。对照组实施基础构音训练,治疗组在对照组的基础上联合综合呼吸训练,2组均治疗4周,观察2组病人治疗前后Frenchay构音障碍评定量表(FDA)评分、最长发音时间(MPT)、不同音节轮替运动速率(DR)和最大吸气压力(MIP)的改变。结果治疗前,2组病人的FDA评分、MPT、不同音节DR和MIP差异均无统计学意义(P>0.05)。治疗后,2组病人的FDA评分、MPT和不同音节DR均较治疗前显著提高(P<0.01),且治疗组FDA评分、MPT、不同音节DR和MIP水平较对照组改善更明显,差异有统计学意义(P<0.05或P<0.01)。结论综合呼吸训练可以促进呼吸与发声的协调性,改善老年帕金森病病人运动减少型构音障碍。

Research on Republic China＇s Diplomat Chengting Thomas WANG： From a Chinese Nationalist to an Internationalist

Chengting Thomas WANG, a Christian went on to be an important Chinese Diplomat. Then after his diplomatic career had ended he focused on his religious beliefs. In the course of this process, he transformed from a nationalist to an internationalist. As a nationalist he represented the interests of China, opposing Western Powers unequal treaties on China. As an internationalist his response to the Peace advocates in Western countries during the two world wars initiated in him taking the route of international cooperation to combat the rise of communism in China. Chengting Thomas WANG changed to an international activists, from nationalists, had very little benefit for his own country.

政府扶持与战略产业技术追赶:全球商用飞机产业的追赶策略

面对西方国家在高端技术领域的不断封锁,中国应该采取何种模式才能实现高新技术产业追赶?对此问题,学界围绕“市场主导”与“政府主导”争论不休。论文结合战略产业技术特征与后发追赶理论,探索追赶策略与技术创新的关系。研究发现:政府扶持模式所具备的行政长期指导与制度网络协调的特征,能够满足战略产业对长期技术积累和技术整合的要求;并且,追赶条件越落后,政府扶持模式对战略产业技术追赶的优势越明显。本文以全球商用飞机产业作为典型案例,通过分析空中客车公司与中国商飞公司的技术追赶历程,展现欧洲政府和中国政府如何通过间接(政策)与直接(国企)扶持手段帮助企业克服技术追赶困难。研究结论表明:发挥政府以及国有体制对战略产业技术追赶的优势,对中国赢得全球技术竞争具有重要的战略意义,也为当下中国探索“新型举国体制”提供实践启示。

镜像疗法对脑卒中患者上肢运动功能和日常生活活动能力影响的Meta分析

目的系统评价镜像疗法(MT)干预是否能有效改善脑卒中患者上肢运动功能和日常生活活动能力(ADL),其改善效果是否受到患者年龄和病程的影响,MT的干预周期、时间、频次等影响因素是否对改善上肢运动功能和ADL具有剂量效应。方法检索Embase、Web of Science、PubMed、Cochrane Library、万方数据库、维普和中国知网等7个数据库,时间范围为建库至2023年4月。筛选MT对脑卒中患者上肢运动功能和ADL的随机对照试验。采用物理治疗证据数据库(PEDro)量表进行质量评估,采用RevMan 5.4.1进行Meta分析,采用R软件进行网状Meta分析,绘制网状Meta分析表和累计概率表进行排序比较,采用Stata 17.0软件绘制漏斗图检验结局指标发表偏倚情况。采用GRADE对结局指标进行证据质量评价。结果共纳入13篇文献,涉及532例患者。PEDro评分6~8分。多数文献未完整汇报盲法情况或未实施分配隐藏,可能存在一定局限。MT能够提高脑卒中患者的Fugl-Meyer评定量表上肢部分评分(n=466,MD=6.05,95%CI 3.44~8.66,P<0.001)、(改良)Barthel指数(n=230,MD=9.95,95%CI 6.23~13.68,P<0.001)和功能性独立测量评分(n=147,MD=4.17,95%CI 2.61~5.72,P<0.001)。网状Meta分析显示,MT对于40~59岁,病程≤3个月的脑卒中患者上肢运动功能干预效果更好;干预周期≤4周、单次干预时间≤30 min、每天干预时间>30 min和每天2次的MT干预处方对于脑卒中患者的上肢运动功能改善效果更好。结论MT对脑卒中患者上肢运动功能和ADL有较显著的改善效果,上肢运动功能改善效果受到患者年龄和病程的影响,且与干预的周期、时间和频次存在一定程度的剂量效应。