大动脉粥样硬化性脑卒中与心脏功能关系的临床研究

目的分析主动脉弓粥样硬化性脑卒中与颅内外动脉粥样硬化性脑卒中心脏功能的区别,探讨心脏功能对大动脉粥样硬化性脑卒中预后的影响。方法选取2014年1月至2017年10月在解放军联勤保障部队第920医院住院的首次急性缺血性脑卒中患者共846例,其中符合中国缺血性卒中亚型分型的大动脉粥样硬化患者552例,分为颅内外动脉粥样硬化组507例,主动脉弓粥样硬化组45例。分析主动脉弓粥样硬化性脑卒中与颅内外动脉粥样硬化性脑卒中心脏功能的区别,采用多因素回归分析心脏功能对卒中30 d预后的影响。结果(1)主动脉弓粥样硬化组患者左室射血分数[(55.14±9.41)vs(62.99±10.44),P<0.001]、左室缩短率(中位数28.00 vs 35.00,P<0.001)低于颅内外动脉粥样硬化组;主动脉弓粥样硬化组患者收缩末期容量大于颅内外动脉粥样硬化组(中位数45.00 vs 36.00,P=0.001);(2)大动脉粥样硬化性脑卒中患者,每搏输出量降低(OR=0.968,95%CI:0.951~0.985)、冠心病(OR=2.063,95%CI:1.050~4.055)增加30 d残疾风险;心输出量增加(HR=1.582,95%CI:1.170~2.139)、高尿酸血症(HR=5.411,95%CI:1.265~23.153)、年龄(HR=1.104,95%CI:1.023~1.192)增加30 d死亡风险。结论主动脉弓粥样硬化性脑卒中患者心脏收缩功能比颅内外动脉粥样硬化性脑卒中患者差。大动脉粥样硬化性脑卒中患者,冠心病、每搏输出量降低与30 d残疾独立相关;心输出量增加、年龄、高尿酸血症与30d死亡独立相关。

液态Ag-O系表面张力和表面过剩量的理论计算

本工作利用表面能与内聚能的比例关系,计算了液态Ag的表面张力和表面过剩熵。结果显示,随着温度的升高,表面张力近似线性下降,表面过剩熵也逐渐减小,这表明液态Ag表面总是保持有序结构。在此基础上,证明了Ag-O系具有理想溶体性质,并简化了Butler方程,修正了液态Ag-O系表面张力关于氧气压力和温度的预测模型。结果表明,当氧气压力低于10 kPa时,液态Ag-O系的表面张力与温度呈负相关;而当氧气压力高于10 kPa时,随着温度的升高,表面张力呈现先增大后减小的趋势。此外,还探究了O原子的表面偏析行为。研究发现,表面偏析因子与温度和氧气压力均呈负相关,在较低的温度和氧气压力下,O原子倾向富集于表面。

Decoupled knowledge distillation method based on meta-learning

With the advancement of deep learning techniques,the number of model parameters has been increasing,leading to significant memory consumption and limits in the deployment of such models in real-time applications.To reduce the number of model parameters and enhance the generalization capability of neural networks,we propose a method called Decoupled MetaDistil,which involves decoupled meta-distillation.This method utilizes meta-learning to guide the teacher model and dynamically adjusts the knowledge transfer strategy based on feedback from the student model,thereby improving the generalization ability.Furthermore,we introduce a decoupled loss method to explicitly transfer positive sample knowledge and explore the potential of negative samples knowledge.Extensive experiments demonstrate the effectiveness of our method.

Drug resistance mechanisms and novel drug targets for tuberculosis therapy

Drug-resistant tuberculosis （TB） poses a significant challenge to the successful treatment and control of TB worldwide. Resistance to anti-TB drugs has existed since the beginning of the chemotherapy era. New insights into the resistant mechanisms of anti-TB drugs have been provided. Better understanding of drug resistance mechanisms helps in the development of new tools for the rapid diagnosis of drug- resistant TB. There is also a pressing need in the development of new drugs with novel targets to improve the current treatment of TB and to prevent the emergence of drug resistance in Mycobacterium tuber- culosis. This review summarizes the anti-TB drug resistance mechanisms, furnishes some possible novel drug targets in the development of new agents for TB therapy and discusses the usefulness using known targets to develop new anti-TB drugs. Whole genome sequencing is currently an advanced technology to uncover drug resistance mechanisms in M. tuberculosis. However, further research is required to unravel the significance of some newly discovered gene mutations in their contribution to drug resistance.

Research and clinical translation of trilayer stent-graft of expanded polytetrafluoroethylene for interventional treatment of aortic dissection

The aortic dissection(AD)is a life-threatening disease.The transcatheter endovascular aortic repair(EVAR)affords a minimally invasive technique to save the lives of these critical patients,and an appropriate stent-graft gets to be the key medical device during an EVAR procedure.Herein,we report a trilayer stent-graft and corresponding delivery system used for the treatment of the AD disease.The stent-graft is made of nitinol stents with an asymmetric Z-wave design and two expanded polytetrafluoroethylene(ePTFE)membranes.Each of the inner and outer surfaces of the stent-graft was covered by an ePTFE membrane,and the two membranes were then sintered together.The biological studies of the sintered ePTFE membranes indicated that the stent-graft had excellent cytocompatibility and hemocompatibility in vitro.Both the stent-graft and the delivery system exhibited satisfactory mechanical properties and operability.The safety and efficacy of this stent-graft and the corresponding delivery system were demonstrated in vivo.In nine canine experiments,the blood vessels of the animals implanted with the stent-grafts were of good patency,and there were no thrombus and obvious stenosis by angiography after implantation for 6months.Furthermore,all of the nine clinical cases experienced successful implantation using the stent-graft and its postrelease delivery system,and the 1-year follow-ups indicated the preliminary safety and efficacy of the trilayer stent-graft with an asymmetric Z-wave design for interventional treatment.

Advances in the development of molecular genetic tools for Mycobacterium tuberculosis

Mycobacterium tuberculosis, a Gram-positive bacterium of great clinical relevance, is a lethal pathogen owing to its complex physiological characteristics and development of drug resistance. Several molecular genetic tools have been developed in the past few decades to study this microorganism. These tools have been instrumental in understanding how M. tuberculosis became a successful pathogen. Advanced molecular genetic tools have played a significant role in exploring the complex pathways involved in M. tuberculosis pathogenesis. Here, we review various molecular genetic tools used in the study of M. tuberculosis. Further, we discuss the applications of clustered regularly interspaced short palindromic repeat interference（CRISPRi）, a novel technology recently applied in M. tuberculosis research to study target gene functions. Finally, prospective outcomes of the applications of molecular techniques in the field of M. tuberculosis genetic research are also discussed.

Biaxial stretching of polytetrafluoroethylene in industrial scale to fabricate medical ePTFE membrane with node-fibril microstructure

Expanded polytetrafluoroethylene(ePTFE)is promising in biomedical fields such as covered stents and plastic surgery owing to its excellent biocompatibility and mechanical properties.However,ePTFE material prepared by the traditional biaxial stretching process is with thicker middle and thinner sides due to the bowing effect,which poses a major problem in industrial-scale fabrication.To solve this problem,we design an olive-shaped winding roller to provide the middle part of the ePTFE tape with a greater longitudinal stretching amplitude than the two sides,so as to make up for the excessive longitudinal retraction tendency of the middle part when it is transversely stretched.The as-fabricated ePTFE membrane has,as designed,uniform thickness and node-fibril microstructure.In addition,we examine the effects of mass ratio of lubricant to PTFE powder,biaxial stretching ratio and sintering temperature on the performance of the resultant ePTFE membranes.Particularly,the relation between the internal microstructure of the ePTFE membrane and its mechanical properties is revealed.Besides stable mechanical properties,the sintered ePTFE membrane exhibits satisfactory biological properties.We make a series of biological assessments including in vitro hemolysis,coagulation,bacterial reverse mutation and in vivo thrombosis,intracutaneous reactivity test,pyrogen test and subchronic systemic toxicity test;all of the results meet the relevant international standards.The muscle implantation of the sintered ePTFE membrane into rabbits indicates acceptable inflammatory reactions of our sintered ePTFE membrane fabricated on industrial scale.Such a medical-grade raw material with the unique physical form and condensed-state microstructure is expected to afford an inert biomaterial potentially for stent-graft membrane.

Pt nanodendrites with (111) crystalline facet as an efficient, stable and pH-universal catalyst for electrochemical hydrogen production

High-performance nanomaterial catalysts for hydrogen evolution reaction via electrochemical water splitting are significant to the development of hydrogen energy.In this work,we report a robust and highly active catalyst fabricated through direct electrochemical deposition of Pt nanodendrites at the surface of activated carbon(Pt NDs).Owing to the large elect roc he mically active area and the exposed(111) facet of Pt,Pt NDs exhibits outstanding activity towards hydrogen evolution reaction with a low requiring overpotential of 0.027 V at 10 mA/cm2 and Tafel slope of ≈22 mV/dec in acidic media.In addition,the hydrogen yield of Pt NDs is 30%-45% larger than that of commercial Pt/C at the same Pt loadings.Moreover,Pt NDs exhibits excellent lo ng-term durability whose hydrogen production efficiency remains unchanged after six-hour hydrogen production,while the efficiency of commercial Pt/C catalyst decayed 9% under the same circumstance.Considering the superiority of catalytic activity and stability,this Pt NDs present great potentiality towards practical hydrogen production application.