Controllable step-flow growth of GaN on patterned freestanding substrate

A new kind of step-flow growth mode is proposed,which adopts sidewall as step source on patterned GaN substrate.The terrace width of steps originated from the sidewall was found to change with the growth temperature and ammonia flux.The growth mechanism is explained and simulated based on step motion model.This work helps better understand the behaviors of step advancement and puts forward a method of precisely modulating atomic steps.

基于TeamSTEPPS理论的案例情景教学法在急诊护理团队培训中的应用

急诊科具有危重患者多,突发状况多,医疗风险高等特点,目前国内大多数医院急诊科护士以团队形式开展工作,但临床工作中易出现职责分工不明确、配合不协调、组织抢救混乱等问题^([1])。团队培训是增强团队优质高效协作的重要途径^([2]),为进一步提升急诊护理团队协作,保障患者安全,本次研究将前期基于提高医疗质量和患者安全的团队策略与工具(team strategies and tools to enhance performance and patient safety,TeamSTEPPS)理论构建的急诊护理团队培训方案^([3])进行临床应用,取得了较好的效果。现报道如下。

谐波驱动系统Back-stepping滑模控制研究

针对谐波传动系统动力学模型中存在的柔性变形、摩擦和运动误差等非线性因素。为了提高系统的传动精度,针对系统非线性刚度和静态误差因素进行了建模,并提出了一种Back-stepping滑模控制方法。利用Lyapunov稳定性理论,证明了闭环系统的误差是一致有界的。仿真结果表明,与PID控制相比,采用Back-stepping滑模控制,系统传动误差曲线峰峰值减小66.63%;负载端角速率误差曲线峰峰值减小77.35%。Back-stepping滑模控制能有效地补偿系统传动误差,抑制其负载端的速度波动,提高了系统的传动精度。

Stability analysis of intermittently jointed rock slopes based on the stepped failure mode

In practical engineering,due to the noncontinuity characteristics of joints in rock slopes,in addition to plane failure,stepped sliding failure may occur for intermittently jointed rock slopes.Especially for intermittently bedding jointed rock slopes,the correlation and difference in strength parameters between joints and rock bridges,along with the various failure modes and intermittency of rock bridges,contribute to the complexity of stepped failure modes and the unpredictability of failure regions.Based on the upper-bound limit analysis method and multi-sliders step-path failure mode,considering the shear and tensile failure of rock bridges and the weakened relationship between the strength parameters of rock bridges and jointed surfaces,by introducing the modified M-C failure criterion and the formula for calculating the energy consumption of tensile failure of rock bridges,two failure mechanisms are constructed to obtain the safety factor(F_(s))of intermittently jointed rock slopes.The sequential quadratic programming method is used to obtain the optimal upper-bound solution for F_(s).The influence of multiple key parameters(slope height H,horizontal distance L,Slope angleβ,shear strength parameters of the rock bridgeφr and cr,Dimensionless parameter u,weakening coefficients of the internal friction angle and cohesion between the rock bridges and joint surfaces Kφand Kc)on the stability analysis of intermittently jointed rock slopes under the shear failure mode of rock bridges as well as under the tensile failure mode is also explored.The reliability of the failure mechanisms is verified by comparative analysis with theoretical results,numerical results,and landslide cases,and the variation rules of F_(s)with each key parameter are obtained.The results show that F_(s) varies linearly withφr and cr of the rock bridge and with K_(φ)and K_(c),whereas F_(s)changes nonlinearly with H and L.In particular,with the increase in Kφand Kc,Fs increases by approximately 52.78%and 171.02%on average,respectively.For rock bridge tensile failure,F_(s) shows a nonlinearly positive correlation withφr,cr,Kφand Kc.In particular,with the increase in Kφand Kc,Fs increases by approximately 13%and 61.69%on average,respectively.Fs decreases rapidly with increasing slope gradientβand decreasing dimensionless parameterμ.When Kφand Kc are both less than 1.0,the stepped sliding surface occurs more easily than the plane failure surface,especially in the case of tensile failure of the rock bridge.In addition,rock slopes with higher strength parameters,taller heights,and greater weakening coefficients are prone to rock bridge tension failure with lower Fs,and more attention should be given to the occurrence of such accidents in actual engineering.

"Five steps four quadrants" modularized en bloc dissection technique for accessing hepatic hilum lymph nodes in laparoscopic pancreaticoduodenectomy

BACKGROUND Although en bloc dissection of hepatic hilum lymph nodes has many advantages in radical tumor treatment,the feasibility and safety of this approach for laparo-scopic pancreaticoduodenectomy(LPD)require further clinical evaluation and investigation.AIM To explore the application value of the"five steps four quadrants"modularized en bloc dissection technique for accessing hepatic hilum lymph nodes in LPD patients.METHODS A total of 52 patients who underwent LPD via the"five steps four quadrants"modularized en bloc dissection technique for hepatic hilum lymph nodes from April 2021 to July 2023 in our department were analyzed retrospectively.The patients'body mass index(BMI),preoperative laboratory indices,intraoperative variables and postoperative complications were recorded.The relationships between preoperative data and intraoperative lymph node dissection time and blood loss were also analyzed.RESULTS Among the 52 patients,36 were males and 16 were females,and the average age was 62.2±11.0 years.There were 26 patients with pancreatic head cancer,16 patients with periampullary cancer,and 10 patients with distal bile duct cancer.The BMI was 22.3±3.3 kg/m²,and the median total bilirubin(TBIL)concentration was 57.7(16.0-155.7)µmol/L.All patients successfully underwent the"five steps four quadrants"modularized en bloc dissection technique without lymph node clearance-related complications such as postoperative bleeding or lymphatic leakage.Correlation analysis revealed significant associations between preoperative BMI(r=0.3581,P=0.0091),TBIL level(r=0.2988,P=0.0341),prothrombin time(r=0.3018,P=0.0297)and lymph node dissection time.Moreover,dissection time was significantly correlated with intraoperative blood loss(r=0.7744,P<0.0001).Further stratified analysis demonstrated that patients with a preoperative BMI≥21.9 kg/m²and a TIBL concentration≥57.7μmol/L had significantly longer lymph node dissection times(both P<0.05).CONCLUSION The"five steps four quadrants"modularized en bloc dissection technique for accessing the hepatic hilum lymph node is safe and feasible for LPD.This technique is expected to improve the efficiency of hepatic hilum lymph node dissection and shorten the learning curve;thus,it is worthy of further clinical promotion and application.

Contribution to the Full 3D Finite Element Modelling of a Hybrid Stepping Motor with and without Current in the Coils

The paper presents our contribution to the full 3D finite element modelling of a hybrid stepping motor using COMSOL Multiphysics software. This type of four-phase motor has a permanent magnet interposed between the two identical and coaxial half stators. The calculation of the field with or without current in the windings (respectively with or without permanent magnet) is done using a mixed formulation with strong coupling. In addition, the local high saturation of the ferromagnetic material and the radial and axial components of the magnetic flux are taken into account. The results obtained make it possible to clearly observe, as a function of the intensity of the bus current or the remanent induction, the saturation zones, the lines, the orientations and the magnetic flux densities. 3D finite element modelling provide more accurate numerical data on the magnetic field through multiphysics analysis. This analysis considers the actual operating conditions and leads to the design of an optimized machine structure, with or without current in the windings and/or permanent magnet.

A Clean Switch Inner Mongolian town takes giant steps in transitioning to clean energy production

Staff at the Ruichen Wanniu Livestock Farm in Jungar Zhao Town,Jungar Banner,Inner Mongolia,are consistently busy,even during important festivals.

基于STEP模式下的计算机专业课堂实践教学效果提升策略

本研究的目的在于探讨基于STEP模式的计算机专业课堂实践教学效果提升策略。本研究采用了文献研究和理论分析的方法,探讨了STEP模式在计算机专业课堂中的优势,并提出了提升教学效果的策略。研究结果表明,STEP模式在计算机专业课堂实践教学中有利于跨学科整合、解决实际问题、促进团队协作。为了提高教学效果,本研究提出了多元化教学手段、师资队伍培训、及时更新理论教材等策略。本研究的结论是,采用STEP模式并实施相应策略可以有效提升计算机专业课堂实践教学的效果,帮助学生更好地适应现实问题解决和职业需求。

IVUS引导下Step-Crush术治疗左主干分叉病变对支架贴壁情况及患者预后的影响

目的:分析血管内超声(IVUS)引导下Step-Crush术治疗左主干分叉病变对支架贴壁情况及患者预后的影响。方法:回顾分析2021年3月—2022年12月于九江市第一人民医院总院心血管内科就诊的左主干分叉病变患者60例,根据手术方式将患者分为IVUS组(n=34,采用IVUS引导下StepCrush术)和常规组(n=26,采用常规Step-Crush术)。对比两组支架情况(最大支架直径、左主干支架长度、支架贴壁不良发生率、支架边缘夹层发生率)、球囊参数(球囊最大直径、球囊最大压力)、心功能指标[左室射血分数(LVEF)、左室舒张末内径(LVEDD)]及心血管不良事件发生率。结果:相较于常规组,IVUS组最大支架直径、左主干支架长度、球囊最大直径均更长,球囊最大压力更大(P<0.05);术后2个月,IVUS组LVEF较常规组更高,LVEDD较常规组更低,差异均有统计学意义(P<0.05);IVUS组支架贴壁不良发生率、心血管不良事件发生率均更低,差异均有统计学意义(P<0.05)。两组支架边缘夹层发生率对比,差异无统计学意义(P>0.05)。结论:IVUS应用于Step-Crush术中可改善左主干分叉病变患者支架置入情况,降低支架贴壁发生率,有效预防心血管不良事件发生。

产品模型数据交换标准STEP研究

在设计和制造中,许多系统过去常常要处理技术产品数据。每个系统有它自己的数据格式,所以相同的信息必然在多个系统中多次存储,这会导致了信息的冗余和错误。STEP是一个广泛使用的ISO标准(ISO10303),描述了表示和交换数字产品信息的方式。研究了STEP的标准体系结构,并研究不同应用对象的STEP和STEP未来的发展趋势。

基于STEP工程教育理念的卓越工程师培养模式

为了适应新形势下卓越工程师人才培养的需求,在工程教育改革和工程认证大环境下,对标国际一流高校,借鉴CDIO等国内外先进的教育理念,并结合北京航空航天大学工程教育实际,提出了对支撑工程教育、培养卓越工程师具有普适性的STEP(即软件、理论、实验、项目)教育模式。STEP教育模式构建了项目驱动、理论教学与实验教学协同、软件工具支撑的课程体系,科教融合、虚实结合、竞赛聚合的教学模式,以及提升教学能力、完善实践环境、改进质量评价体系的保障机制。STEP教育模式已在北京航空航天大学相关学院部分课程建设中进行了推广和实践,并取得了良好的教学实践效果。

阿尔茨海默病细胞模型中β淀粉样蛋白介导ERK信号通路的STEP_(61)负性调控

背景:研究表明纹状体富集的酪氨酸磷酸酶61(striatal-enriched phosphatase,STEP_(61))在突触可塑性方面发挥重要作用。STEP位于后突触末端,影响突触增强的形成,可能的机制是使关键性信号蛋白如MAPK激酶ERK1/2去磷酸化并失活。目的:探讨STEP_(61)负性调控阿尔茨海默病细胞模型中β淀粉样蛋白介导的ERK信号通路的机制。方法:实验分3组,正常组为C57BL/6小鼠原代皮质神经元细胞;阿尔茨海默病细胞模型组是利用1μmol/L凝聚态的β淀粉样蛋白1-42加入皮质神经元细胞中1 h作为阿尔茨海默病细胞模型;β淀粉样蛋白1-42+RNAi组为在阿尔茨海默病细胞模型基础上,利用sRNAi技术制作STEP_(61)基因沉默组。应用Western Blot技术检测STEP_(61)的RNAi对ERK信号通路的影响。结果与结论:Western blot结果显示,阿尔茨海默病细胞模型组与正常组相比STEP_(61)蛋白表达增加了223%(P<0.05),使磷酸化STEP_(61)的比例减少到(75.6±4.6)%(P<0.05)。β淀粉样蛋白1-42+RNAi组STEP_(61)磷酸化的比例与阿尔茨海默病细胞模型组相比差异无显著性意义。同时阿尔茨海默病细胞模型组pE RK1/2的蛋白表达量较对照组减少(P<0.05),而β淀粉样蛋白1-42+RNAi组p ERK1/2的蛋白表达量较阿尔茨海默病细胞模型组显著增加(P<0.05)。结果说明:在阿尔茨海默细胞模型中证实了STEP_(61)调控β淀粉样蛋白介导的ERKs活性,并且很可能是通过脱磷酸化使他们失活而实现的。

CMT Cycle Step工艺参数对焊缝表面特征纹路及成形尺寸的影响

采用CMT Cycle Step焊接工艺进行平板堆焊正交试验,研究了送丝速度、焊接速度、熔滴数量和间隔时间四个参数对焊缝表面特征纹路及成形尺寸的影响,建立了各参数与焊缝表面鱼鳞纹步长S、焊缝熔宽B、堆焊层厚度h之间的回归模型.结果表明,随着焊接速度、熔滴数量和间隔时间的增大,焊缝表面鱼鳞纹步长S呈逐渐增大的趋势.适当减小焊接速度和间隔时间,可有效减小焊缝表面高度差Δh,提高焊缝表面成形质量.随着送丝速度和熔滴数量的增大,焊缝熔宽B和堆焊层厚度h均逐渐增大;随着焊接速度的增大,焊缝熔宽B和堆焊层厚度h逐渐减小.根据理论分析和回归分析得到准确性较高的回归方程,为预测焊接焊缝成形以及优化焊接工艺参数提供理论依据.创新点:(1)系统研究了CMT Cycle Step焊接工艺参数对焊缝成形的影响规律,有助于采用该方法解决点焊、热敏感材料焊接、电弧增材制造等领域的相关技术难题.(2)建立了CMT Cycle Step焊接工艺的送丝速度、焊接速度、熔滴数量和间隔时间四个参数对焊缝表面特征纹路及成形尺寸回归模型,为预测焊缝成形以及优化焊接工艺参数提供理论依据.(3)对CMT Cycle Step焊缝表面特征纹路—鱼鳞纹进行量化评价,探究工艺参数对焊缝表面鱼鳞纹步长S和表面高度差Δh的影响规律,有利于获得高表面平整度的焊缝.

基于多线程加速的STEP标准并行解析算法

当前CAD软件加载大型STEP中性文件时速度慢,其效率瓶颈关键在于其解析算法.针对基于单线程的中性标准解析算法已经远远不能满足当前CAD应用需求的问题,提出了一种基于多线程的分层并行数据解析算法,利用当前主流CPU都采用的多核并行架构,大幅提升了STEP文件解析效率.根据模型体中数据的分层特性,算法利用线程池对各层数据解析进行并行加速.文中算法已经在开源几何引擎OpenGE中实现.与OpenCASCADE的对比实验验证了文中算法的有效性.实验结果表明,算法的并行解析程序运行速度相比串行解析程序运行速度提升至原算法的2倍,比OpenCASCADE解析算法快50%.

基于move-step模型的地铁车站站务通信言语特征分析

规范化的通信用语可以减少沟通双方的交流时间,使接收者获取到准确的信息内容。将地铁车站站务通信按内容分为日常运营信息及突发/紧急事件信息两类,并基于move-step模型将这两类信息分为3个沟通阶段及多个沟通步骤。根据地铁车站站务通信的特点,将其言语特征分为呼叫、指示、请求、声明、通知、回复及通话完毕7种类型,并列举了相应的标准化用语范例。

基于TeamSTEPPS理论的急诊护理团队培训模式的构建

提高护理团队合作能力可有效提高救治效率,降低护理过程中不良事件的发生率,进而挽救患者的生命。因此,如何培训优质高效的急诊护理团队,提高团队协作能力是迫切需要解决的问题。提高医疗质量和患者安全的团队策略与工具(team strategies and tools to enhance performance and patient safety,TeamSTEPPS)定义了领导力、情境监控、相互支持和有效沟通这4项可被训练的团队合作核心技能,将临床实践与团队合作技能统一结合,改善医疗过程中的团队表现,以提高医疗、护理质量和患者安全[1]。本次研究旨在探讨基于TeamSTEPPS团队培训的优势,构建急诊护理队伍团队培训模式。

Competition between Stepwise Polarization Switching and Chirality Coupling in Ferroelectric GeS Nanotubes

Ferroelectricity of group-Ⅳ chalcogenides MX(M = Ge,Sn;X = Se,S) monolayers has been extensively investigated.However,how the ferroelectricity evolves in their one-dimensional nanotubes remains largely unclear.Employing an accurate deep-learning interatomic potential of first-principles precision,we uncover a general stepwise mechanism for polarization switching in zigzag and chiral Ge S nanotubes,which has an energy barrier that is substantially lower than the one associated with the conventional one-step switching mechanism.The switching barrier(per atom) gradually decreases with increasing the number of intermediate steps and converges to a value that is almost independent of the tube diameter.In the chiral Ge S nanotubes,the switching path of polarization with chirality coupling is preferred at less intermediate steps.This study unveils novel ferroelectric switching behaviors in one-dimensional nanotubes,which is critical to coupling ferroelectricity and chirality.

Investigation on step overcharge to self-heating behavior and mechanism analysis of lithium ion batteries

To obtain intrinsic overcharge boundary and investigate overcharge mechanism,here we propose an innovative method,the step overcharge test,to reduce the thermal crossover and distinguish the overcharge thermal behavior,including 5%state of charge(SOC)with small current overcharge and resting until the temperature equilibrium under adiabatic conditions.The intrinsic thermal response and the self-excitation behaviour are analysed through temperature and voltage changes during the step overcharge period.Experimental results show that the deintercalated state of the cathode is highly correlated to self-heating parasitic reactions.Before reaching the upper limit of Negative/Positive(N/P)ratio,the temperature changes little,the heat generation is significantly induced by the reversible heat(endothermic)and ohmic heat,which could balance each other.Following that the lithium metal is gradually deposited on the surface of the anode and reacts with electrolyte upon overcharge,inducing selfheating side reaction.However,this spontaneous thermal reaction could be“self-extinguished”.When the lithium in cathode is completely deintercalated,the boundary point of overcharge is about 4.7 V(~148%SOC,>40℃),and from this point,the self-heating behaviour could be continuously triggered until thermal runaway(TR)without additional overcharge.The whole static and spontaneous process lasts for 115 h and the side reaction heat is beyond 320,000 J.The continuous self-excitation behavior inside the battery is attributed to the interaction between the highly oxidized cathode and the solvent,which leads to the dissolution of metal ions.The dissolved metal ions destroy the SEI(solid electrolyte interphase)film on the surface of the deposited Li of anode,which induces the thermal reaction between lithium metal and the solvent.The interaction between cathode,the deposited Li of anode,and solvent promotes the temperature of the battery to rise slowly.When the temperature of the battery reaches more than 60℃,the reaction between lithium metal and solvent is accelerated.After the temperature rises rapidly to the melting point of the separator,it triggers the thermal runaway of the battery due to the short circuit of the battery.

Bionic microchannels for step lifting transpiration

Those various cross-sectional vessels in trees transfer water to as high as 100 meters,but the traditional fabrication methods limit the manufacturing of those vessels,resulting in the non-availability of those bionic microchannels.Herein,we fabricate those bionic microchannels with various cross-sections by employing projection micro-stereolithography(PμSL)based 3D printing technique.The circumradius of bionic microchannels(pentagonal,square,triangle,and five-pointed star)can be as small as 100μm with precisely fabricated sharp corners.What's more,those bionic microchannels demonstrate marvelous microfluidic performance with strong precursor effects enabled by their sharp corners.Most significantly,those special properties of our bionic microchannels enable them outstanding step lifting performance to transport water to tens of millimeters,though the water can only be transported to at most 20 mm for a single bionic microchannel.The mimicked transpiration based on the step lifting of water from bionic microchannels is also achieved.Those precisely fabricated,low-cost,various cross-sectional bionic microchannels promise applications as microfluidic chips,long-distance unpowered water transportation,step lifting,mimicked transpiration,and so on.

Aging effect and test-retest reliability of the sinusoidal harmonic acceleration test and velocity step test using nanotorque rotatory chair

Introduction:Rotatory chair testing has been used to evaluate horizontal canal function.Frequently used tests include sinusoidal harmonic acceleration test(SHAT)and velocity step test(VST).Objectives:Assessment of age effect on the SHAT and VST and assessment of test-retest reliability of the parameters of those two tests.Methods:A prospective study was performed on 100 subjects with no ear or vestibular complaints and normal vestibular evaluation.They were divided into two groups;Group A:below 50 years of age and Group B:50 years of age or above.SHAT was presented at frequencies 0.02,0.04,0.08,0.16,0.32,0.64 Hz with a peak velocity of 60°/s.VST was performed using a maximum velocity of 100°/s with acceleration and deceleration of 200°/s2.Thirty subjects were tested twice to assess reliability.Results:Study participants ranged in age from 20 to 67 years.Regarding group A,the mean age was30.92±7.31 and 55.36±4.61 for group B.No significant differences were found in SHAT parameters between the two groups.As well,there was no significant difference in VST per-rotatory time constant,however,post-rotatory time constant was significantly longer for Group B(P value<0.05).Intraclass correlation coefficient(ICC)values showed moderate to good reliability(ICC 0.5800.818)for SHAT parameters for the lower frequencies and indicated moderate reliability for VST time constant(ICC 0.5090.652).Conclusions:Age has no significant effect on the parameters of SHAT and VST.Test-retest reliability is generally good for both tests.