目的探讨基于MRI的椎体骨质量评分(vertebral bone quality score,VBQ)和终板骨质量评分(endplate bone quality score,EBQ)在经椎间孔腰椎椎间融合(transforaminal lumbar interbody fusion,TLIF)术后cage沉降中的预测价值。方法因腰...目的探讨基于MRI的椎体骨质量评分(vertebral bone quality score,VBQ)和终板骨质量评分(endplate bone quality score,EBQ)在经椎间孔腰椎椎间融合(transforaminal lumbar interbody fusion,TLIF)术后cage沉降中的预测价值。方法因腰椎退行性疾病在我院行TLIF手术的226例患者,根据术后有无cage沉降将患者分为沉降组和非沉降组,比较两组患者VBQ和EBQ评分。通过多元回归分析cage沉降的危险因素,并根据受试者工作特征曲线下面积(AUC)评估VBQ和EBQ预测TLIF术后cage沉降的能力。结果226例患者中30例出现术后cage沉降。沉降组VBQ(3.8±0.4)分,EBQ(5.1±0.7)分,明显高于非沉降组(3.1±0.6)分和(4.2±1.0)分,差异有统计学意义(P<0.001)。多元回归分析显示VBQ(OR=4.258,95%CI:1.983~9.142,P<0.001)和EBQ(OR=1.971,95%CI:1.212~3.203,P=0.006)评分越高,发生cage沉降风险也越大。受试者工作特征曲线结果显示VBQ的AUC为0.843,EBQ的AUC是0.864。VBQ和EBQ预测cage沉降的最佳阈值分别为3.480(敏感性90%;特异性75.5%)和4.620(敏感性96.7%;特异性74.5%)。结论术前VBQ或EBQ评分越高,TLIF术后发生cage沉降风险越大。其中EBQ可能是一个更好的预测融合术后cage沉降的指标。展开更多
目的:探讨后路寰枢椎侧块关节cage植骨融合内固定术治疗难复性寰枢椎脱位的临床疗效,并与经口咽松解后路复位固定融合术进行疗效对比。方法:回顾性分析2018年1月~2022年8月我科采用后路寰枢椎侧块关节cage植骨融合内固定术(23例,cage组...目的:探讨后路寰枢椎侧块关节cage植骨融合内固定术治疗难复性寰枢椎脱位的临床疗效,并与经口咽松解后路复位固定融合术进行疗效对比。方法:回顾性分析2018年1月~2022年8月我科采用后路寰枢椎侧块关节cage植骨融合内固定术(23例,cage组)与经口咽松解后路复位固定融合术(25例,对照组)治疗的难复性寰枢椎脱位患者的临床资料,cage组男8例,女15例,年龄9~79岁(48.35±14.38岁);对照组男6例,女19例,年龄21~69岁(47.84±13.51岁)。记录两组患者手术时间、术中出血量、住院时间及并发症情况,术前、术后及末次随访时使用JOA评分评估患者神经功能状态,测量术前、术后及末次随访时的寰齿间距(atlantodental interval,ADI)、齿状突顶点距离Chamberlain线的垂直距离(vertical distance from odon to idprocess to Chamberlain′s line,DOCL)、延髓颈髓角(cervicomedullary angle,CMA)、斜坡枢椎角(clivus-axial angle,CAA),评估寰枢椎复位情况。评估侧块关节cage及后方植骨融合情况。结果:所有患者内固定位置良好,减压充分复位满意,症状均明显缓解,未出现椎动脉损伤和脊髓损伤加重。cage组手术时间133.04±34.04min、术中出血量119.13±54.77mL、住院时间14.74±6.10d,均明显短于或少于对照组(253.20±53.98min、181.20±45.40mL、23.96±5.47d)。cage组术前JOA、ADI、DOCL、CMA、CAA分别为6.33±1.13分、7.31±3.05mm、9.47±3.32mm、122.89°±12.58°、122.02°±12.50°,术后分别为13.04±2.17分、2.18±0.67mm、0.89±1.00mm、148.81°±5.43°、146.70°±9.32°,末次随访时分别为14.89±1.17分、2.09±0.69mm、0.83±0.86mm、149.10°±5.11°、146.89°±8.95°;对照组术前JOA、ADI、DOCL、CMA、CAA分别为6.76±1.21分、7.70±0.97mm、10.56±1.99mm、121.53°±4.87°、123.77°±8.95°,术后分别为13.26±1.32分、1.89±0.50mm、1.13±1.08mm、151.40°±6.15°、149.86°±5.58°,末次随访时分别为15.02±0.88分、1.87±0.44mm、0.87±1.39mm、149.48°±4.06°、149.94°±6.61°,两组术后及末次随访JOA、ADI、DOCL、CMA及CAA均较术前明显改善(P<0.05),术后JOA评分与末次随访相比存在统计学差异(P<0.05),但ADI、DOCL、CMA及CAA无统计学差异(P>0.05)。cage组仅1例切口感染;对照组3例切口感染(口咽2例,后路1例),1例脑脊液漏。两组随访期间内固定在位稳定,末次随访植骨均达到骨性融合,cage组关节间隙高度无丢失。结论:难复性寰枢椎脱位采用后路寰枢椎侧块关节cage植骨融合内固定术与经口咽松解后路复位固定融合术相比疗效相当,但增加了植骨融合位点,能更有效融合,避免了经口手术,减少了手术时间、术中出血量、住院时间及并发症的发生。展开更多
The semi-hydrogenation of alkyne to form Z-olefins with high conversion and high selectivity is still a huge challenge in the chemical industry.Moreover,flammable and explosive hydrogen as the common hydrogen source o...The semi-hydrogenation of alkyne to form Z-olefins with high conversion and high selectivity is still a huge challenge in the chemical industry.Moreover,flammable and explosive hydrogen as the common hydrogen source of this reaction increases the cost and danger of industrial production.Herein,we connect the photocatalytic hydrogen evolution reaction and the semihydrogenation reaction of alkynes in series and successfully realize the high selective production of Z-alkenes using low-cost,safe,and green water as the proton source.Before the cascade reaction,a series of isomorphic metal–organic cage catalysts(Co_(x)Zn_(8−x)L_(6),x=0,3,4,5,and 8)are designed and synthesized to improve the yield of the photocatalytic hydrogen production.Among them,Co_(5)Zn_(3)L_(6) shows the highest photocatalytic activity,with a H_(2) generation rate of 8.81 mmol g^(−1) h^(−1).Then,Co_(5)Zn_(3)L_(6) is further applied in the above tandem reaction to efficiently reduce alkynes to Z-alkenes under ambient conditions,which can reach high conversion of>98%and high selectivity of>99%,and maintain original catalytic activity after multiple cycles.This“one-pot”tandem reaction can achieve a highly selective and safe stepwise conversion from water into hydrogen into Z-olefins under mild reaction conditions.展开更多
The harmonics that appear in the squirrel cage asynchronous machine have been discussed in great detail in the literature for a long time. However, the systematization of the phenomenon is still pending, so we made an...The harmonics that appear in the squirrel cage asynchronous machine have been discussed in great detail in the literature for a long time. However, the systematization of the phenomenon is still pending, so we made an attempt to fill this gap in the previous parts of our study by elaborating formulas for calculation of parasitic torques. It was a general demand among those who work in this field towards the author to verify his formulas with measurements. In the literature, it seems,only one detailed, purposeful series of measurements has been published so far, the purpose of which was to investigate the effect of the number of rotor slots on the torque-speed characteristic curve of the machine. The main goal of this study is to verify the correctness of the formulas by comparing them with the referred series of measurements. Relying on this, the expected synchronous parasitic torques were developed for the frequently used rotor slot numbers-as a design guide for the engineer.Thus, together with our complete table for radial magnetic pull published in our previous work, the designer has all the principles, data and formulas available for the right number of rotor slots for his given machine and for the drive system. This brings this series of papers to an end.展开更多
To date,there is still a lack of a comprehensive explanation for caged dynamics which is regarded as one of the intricate dynamic behaviors in amorphous alloys.This study focuses on Pd_(82)Si_(18)as the research objec...To date,there is still a lack of a comprehensive explanation for caged dynamics which is regarded as one of the intricate dynamic behaviors in amorphous alloys.This study focuses on Pd_(82)Si_(18)as the research object to further elucidate the underlying mechanism of caged dynamics from multiple perspectives,including the cage's lifetime,atomic local environment,and atomic potential energy.The results reveal that Si atoms exhibit a pronounced cage effect due to the hindrance of Pd atoms,resulting in an anomalous peak in the non-Gaussian parameters.An in-depth investigation was conducted on the caged dynamics differences between fast and slow Si atoms.In comparison to fast Si atoms,slow Si atoms were surrounded by more Pd atoms and occupied lower potential energy states,resulting in smaller diffusion displacements for the slow Si atoms.Concurrently,slow Si atoms tend to be in the centers of smaller clusters with coordination numbers of 9 and 10.During the isothermal relaxation process,clusters with coordination numbers 9 and 10 have longer lifetimes,suggesting that the escape of slow Si atoms from their cages is more challenging.The findings mentioned above hold significant implications for understanding the caged dynamics.展开更多
目的探讨终板体积骨密度(endplate volumetric bone mineral density,EP-vBMD)对侧方入路腰椎融合(lateral lumbar interbody fusion,LLIF)术后Cage沉降的影响。方法选择2018年1月~2020年12月在本院接受LLIF手术治疗的151例患者进行回...目的探讨终板体积骨密度(endplate volumetric bone mineral density,EP-vBMD)对侧方入路腰椎融合(lateral lumbar interbody fusion,LLIF)术后Cage沉降的影响。方法选择2018年1月~2020年12月在本院接受LLIF手术治疗的151例患者进行回顾性分析,收集患者EP-vBMD、椎体体积骨密度(vertebral body volumetric bone mineral density,VB-vBMD)、年龄、性别、体质量指数(body mass index,BMI)、医学共病(糖尿病等)、吸烟、美国麻醉医师协会(american society of anesthesiologists,ASA)评分、查尔森共病指数(charlson comorbidity index,CCI)、手术节段、手术椎体和是否使用后路螺钉固定等资料。根据术后1年患者是否发生Cage沉降,将患者分为Cage沉降组和非沉降组,比较两组患者临床资料差异,将单因素分析P<0.2的变量进一步采用多因素Logsitic回归分析,观察EP-vBMD对终板沉陷的影响。结果Cage沉降患者的VB-vBMD和EP-vBMD水平均低于非Cage沉降患者,差异均有统计学意义(P<0.05)。Cage沉降组患者年龄高于非Cage沉降组患者,差异有统计学意义(P<0.05);Cage沉降组和非Cage沉降组患者性别、吸烟、糖尿病、后路螺钉固定等资料差异均有统计学意义(P<0.05)。多因素Logistic回归分析显示,EP-vBMD和应用后路螺钉固定均是Cage沉降的保护性因素(P<0.05)。结论低EP-vBMD是LLIF术后Cage沉降的风险因素,对患者进行LLIF时,应考虑术前EP-vBMD的测量。展开更多
Flat metal strips are deformed progressively into profiles with certain geometry sections by a series of successive rotating rolls at the room temperature, and it is called the cold roll-forming. An effective method i...Flat metal strips are deformed progressively into profiles with certain geometry sections by a series of successive rotating rolls at the room temperature, and it is called the cold roll-forming. An effective method is given for roll design to avoid major defects via finite element method （FEM） simulation using a booting model. The simulation gives reasonable fit to the actual product in the two major roll-forming defects, i.e. , edge wave and springback. The redesigned rolls using the approach of multi-stand FEM simulation can effectively control these two defects.展开更多
To simulate the process of cold roll-forming process, a new method isadopted. The theoretical foundation of this method is an elastic-plastic large deformation splinefinite strip method based on object-oriented progra...To simulate the process of cold roll-forming process, a new method isadopted. The theoretical foundation of this method is an elastic-plastic large deformation splinefinite strip method based on object-oriented programming. Combined with the computer graphicstechnology, the visual simulation of cold roll-forming is completed and the system is established.By analyzing common channel steel, the process is shown and explained including theory method, modeland result display. So the simulation system is already a kind of mature and effective tool toanalyze the process of cold roll forming.展开更多
The magnetic field generated in the air gap of the cage asynchronous machine and the harmonics of the magnetomotive forces creating that magnetic field,as well as the synchronous parasitic torques,radial magnetic forc...The magnetic field generated in the air gap of the cage asynchronous machine and the harmonics of the magnetomotive forces creating that magnetic field,as well as the synchronous parasitic torques,radial magnetic forces have been discussed in great detail in the literature,but always separately,for a long time.However,systematization of the phenomenon still awaits.Therefore,it is worth summarizing the completeness of the phenomena in a single study–with a new approach at the same time-in order to reveal the relationships between them.The role of rotor slot number is emphasized much more than before.New formulas derived for both synchronous torques and radial magnetic forces are used for further investigation.It will be shown that both phenomena in subject must be treated together.Formulas will be provided to take into account attenuation.Design guide will be provided to avoid dangerous rotor slot numbers.It will be shown that the generation of synchronous torques and radial magnetic forces do not depend–in this new approach-on the slot combination,but on the rotor slot number itself.展开更多
The magnetic field generated in the air gap of the cage asynchronous machine and the harmonics of the magnetomotive forces creating that magnetic field, as well as the related differential leakage, attenuation, asynch...The magnetic field generated in the air gap of the cage asynchronous machine and the harmonics of the magnetomotive forces creating that magnetic field, as well as the related differential leakage, attenuation, asynchronous parasitic torques have been discussed in great detail in the literature, but always separately, for a long time. However, systematization of the phenomenon still awaits. Therefore, it is worth summarizing the completeness of the phenomena in a single study – with a new approach at the same time-in order to reveal the relationships between them. The role of rotor slot number is emphasized much more than before. An existing, commonly used, but still impractical basic figure has been modified to more clearly demonstrate the response of the rotor for the harmonics of the stator. The need to treat differential leakage, asynchronous parasitic torques and attenuation together will be demonstrated: new formula for asynchronous parasitic torque is derived;the long-used characteristic curves for differential leakage and attenuation used separately so far was merged into one, correct curve in order to provide a correct design guide for the engineers.展开更多
目的:通过系统评价的方法分析影响腰椎椎体间融合术后cage后移(cage retropulsion,CR)发生的危险因素。方法:检索PubMed、Embase、Cochrane Library、Web of Science、中国生物医学文献数据库(CBM)、中国知网(CNKI)、万方数据库和维普...目的:通过系统评价的方法分析影响腰椎椎体间融合术后cage后移(cage retropulsion,CR)发生的危险因素。方法:检索PubMed、Embase、Cochrane Library、Web of Science、中国生物医学文献数据库(CBM)、中国知网(CNKI)、万方数据库和维普数据库,收集各数据库建库至2023年4月有关影响腰椎椎体间融合术后CR危险因素的文献,研究类型为队列研究及病例对照研究,采用纽卡斯尔-渥太华质量评估量表(Newcastle-Ottawa scale,NOS)对纳入研究进行质量评价,提取纳入研究的基本信息,包括年龄及性别等以及CR发生相关研究因素,如骨质疏松、终板损伤、螺钉松动、梨形椎间隙、cage形状、cage置入深度及手术时长、出血量等。评价纳入研究的偏倚风险后,使用Stata14.0软件进行Meta分析。结果:共纳入16篇相关文献,其中15篇文献为回顾性病例对照研究,1篇为前瞻性队列研究,均为中等及以上质量研究,NOS评分均≥7分。总样本量12667例,其中发生CR者(CR组)326例,未发生CR者(nCR组)12341例,CR发生率为2.83%。Meta分析结果显示:性别(男性)[比值比(odds ratio,OR)=1.264,95%置信区间(confidence interval,CI)(1.003~1.593),P=0.047]、年龄[效应量标准化平均差(standardized mean difference,SMD)=0.237,95%CI(0.054~0.419),P=0.011]、骨质疏松[OR=3.126,95%CI(1.040~9.401),P=0.042]、骨终板损伤[OR=8.161,95%CI(3.711~17.945),P=0.000]、螺钉松动[OR=7.978,95%CI(3.487~18.255),P=0.000]、梨形椎间隙[OR=6.037,95%CI(2.381~15.305),P=0.000]、cage置入深度不足[OR=5.157,95%CI(1.760~15.111),P=0.003]是腰椎椎体间融合术后发生CR的危险因素。结论:性别(男性)、高龄、骨质疏松、骨终板损伤、螺钉松动、梨形椎间隙、cage置入深度不足与腰椎椎体间融合术后发生CR密切相关,随访期间应对此类患者密切观察,预防发生严重cage移位的并发症。展开更多
文摘目的探讨基于MRI的椎体骨质量评分(vertebral bone quality score,VBQ)和终板骨质量评分(endplate bone quality score,EBQ)在经椎间孔腰椎椎间融合(transforaminal lumbar interbody fusion,TLIF)术后cage沉降中的预测价值。方法因腰椎退行性疾病在我院行TLIF手术的226例患者,根据术后有无cage沉降将患者分为沉降组和非沉降组,比较两组患者VBQ和EBQ评分。通过多元回归分析cage沉降的危险因素,并根据受试者工作特征曲线下面积(AUC)评估VBQ和EBQ预测TLIF术后cage沉降的能力。结果226例患者中30例出现术后cage沉降。沉降组VBQ(3.8±0.4)分,EBQ(5.1±0.7)分,明显高于非沉降组(3.1±0.6)分和(4.2±1.0)分,差异有统计学意义(P<0.001)。多元回归分析显示VBQ(OR=4.258,95%CI:1.983~9.142,P<0.001)和EBQ(OR=1.971,95%CI:1.212~3.203,P=0.006)评分越高,发生cage沉降风险也越大。受试者工作特征曲线结果显示VBQ的AUC为0.843,EBQ的AUC是0.864。VBQ和EBQ预测cage沉降的最佳阈值分别为3.480(敏感性90%;特异性75.5%)和4.620(敏感性96.7%;特异性74.5%)。结论术前VBQ或EBQ评分越高,TLIF术后发生cage沉降风险越大。其中EBQ可能是一个更好的预测融合术后cage沉降的指标。
文摘目的:探讨后路寰枢椎侧块关节cage植骨融合内固定术治疗难复性寰枢椎脱位的临床疗效,并与经口咽松解后路复位固定融合术进行疗效对比。方法:回顾性分析2018年1月~2022年8月我科采用后路寰枢椎侧块关节cage植骨融合内固定术(23例,cage组)与经口咽松解后路复位固定融合术(25例,对照组)治疗的难复性寰枢椎脱位患者的临床资料,cage组男8例,女15例,年龄9~79岁(48.35±14.38岁);对照组男6例,女19例,年龄21~69岁(47.84±13.51岁)。记录两组患者手术时间、术中出血量、住院时间及并发症情况,术前、术后及末次随访时使用JOA评分评估患者神经功能状态,测量术前、术后及末次随访时的寰齿间距(atlantodental interval,ADI)、齿状突顶点距离Chamberlain线的垂直距离(vertical distance from odon to idprocess to Chamberlain′s line,DOCL)、延髓颈髓角(cervicomedullary angle,CMA)、斜坡枢椎角(clivus-axial angle,CAA),评估寰枢椎复位情况。评估侧块关节cage及后方植骨融合情况。结果:所有患者内固定位置良好,减压充分复位满意,症状均明显缓解,未出现椎动脉损伤和脊髓损伤加重。cage组手术时间133.04±34.04min、术中出血量119.13±54.77mL、住院时间14.74±6.10d,均明显短于或少于对照组(253.20±53.98min、181.20±45.40mL、23.96±5.47d)。cage组术前JOA、ADI、DOCL、CMA、CAA分别为6.33±1.13分、7.31±3.05mm、9.47±3.32mm、122.89°±12.58°、122.02°±12.50°,术后分别为13.04±2.17分、2.18±0.67mm、0.89±1.00mm、148.81°±5.43°、146.70°±9.32°,末次随访时分别为14.89±1.17分、2.09±0.69mm、0.83±0.86mm、149.10°±5.11°、146.89°±8.95°;对照组术前JOA、ADI、DOCL、CMA、CAA分别为6.76±1.21分、7.70±0.97mm、10.56±1.99mm、121.53°±4.87°、123.77°±8.95°,术后分别为13.26±1.32分、1.89±0.50mm、1.13±1.08mm、151.40°±6.15°、149.86°±5.58°,末次随访时分别为15.02±0.88分、1.87±0.44mm、0.87±1.39mm、149.48°±4.06°、149.94°±6.61°,两组术后及末次随访JOA、ADI、DOCL、CMA及CAA均较术前明显改善(P<0.05),术后JOA评分与末次随访相比存在统计学差异(P<0.05),但ADI、DOCL、CMA及CAA无统计学差异(P>0.05)。cage组仅1例切口感染;对照组3例切口感染(口咽2例,后路1例),1例脑脊液漏。两组随访期间内固定在位稳定,末次随访植骨均达到骨性融合,cage组关节间隙高度无丢失。结论:难复性寰枢椎脱位采用后路寰枢椎侧块关节cage植骨融合内固定术与经口咽松解后路复位固定融合术相比疗效相当,但增加了植骨融合位点,能更有效融合,避免了经口手术,减少了手术时间、术中出血量、住院时间及并发症的发生。
基金supported by NSFC(Grant Nos.92061101,22271104,21871141,22225109,and 21901123)the Excellent Youth Foundation of Jiangsu Scientific Committee(BK20211593)+2 种基金the project funded by the China Postdoctoral Science Foundation(2018M630572)the Priority Academic Program Development of Jiangsu Higher Education Institutions,and the Foundation of Jiangsu Collaborative Innovation Center of Biomedical Functional Materials,the National Key Research and Development Project of China(Grant No.2021YFC2100100)the Natural Science Foundation of Jiangsu Province(Grant No.BK20190694)。
文摘The semi-hydrogenation of alkyne to form Z-olefins with high conversion and high selectivity is still a huge challenge in the chemical industry.Moreover,flammable and explosive hydrogen as the common hydrogen source of this reaction increases the cost and danger of industrial production.Herein,we connect the photocatalytic hydrogen evolution reaction and the semihydrogenation reaction of alkynes in series and successfully realize the high selective production of Z-alkenes using low-cost,safe,and green water as the proton source.Before the cascade reaction,a series of isomorphic metal–organic cage catalysts(Co_(x)Zn_(8−x)L_(6),x=0,3,4,5,and 8)are designed and synthesized to improve the yield of the photocatalytic hydrogen production.Among them,Co_(5)Zn_(3)L_(6) shows the highest photocatalytic activity,with a H_(2) generation rate of 8.81 mmol g^(−1) h^(−1).Then,Co_(5)Zn_(3)L_(6) is further applied in the above tandem reaction to efficiently reduce alkynes to Z-alkenes under ambient conditions,which can reach high conversion of>98%and high selectivity of>99%,and maintain original catalytic activity after multiple cycles.This“one-pot”tandem reaction can achieve a highly selective and safe stepwise conversion from water into hydrogen into Z-olefins under mild reaction conditions.
文摘The harmonics that appear in the squirrel cage asynchronous machine have been discussed in great detail in the literature for a long time. However, the systematization of the phenomenon is still pending, so we made an attempt to fill this gap in the previous parts of our study by elaborating formulas for calculation of parasitic torques. It was a general demand among those who work in this field towards the author to verify his formulas with measurements. In the literature, it seems,only one detailed, purposeful series of measurements has been published so far, the purpose of which was to investigate the effect of the number of rotor slots on the torque-speed characteristic curve of the machine. The main goal of this study is to verify the correctness of the formulas by comparing them with the referred series of measurements. Relying on this, the expected synchronous parasitic torques were developed for the frequently used rotor slot numbers-as a design guide for the engineer.Thus, together with our complete table for radial magnetic pull published in our previous work, the designer has all the principles, data and formulas available for the right number of rotor slots for his given machine and for the drive system. This brings this series of papers to an end.
基金Project supported by the National Natural Science Foundation of China (Grant No.51701071)the Natural Science Foundation of Hunan Province,China (Grant Nos.2022JJ50115 and 2021JJ30179)the Research Foundation of the Education Bureau of Hunan Province,China (Grant No.22A0522)。
文摘To date,there is still a lack of a comprehensive explanation for caged dynamics which is regarded as one of the intricate dynamic behaviors in amorphous alloys.This study focuses on Pd_(82)Si_(18)as the research object to further elucidate the underlying mechanism of caged dynamics from multiple perspectives,including the cage's lifetime,atomic local environment,and atomic potential energy.The results reveal that Si atoms exhibit a pronounced cage effect due to the hindrance of Pd atoms,resulting in an anomalous peak in the non-Gaussian parameters.An in-depth investigation was conducted on the caged dynamics differences between fast and slow Si atoms.In comparison to fast Si atoms,slow Si atoms were surrounded by more Pd atoms and occupied lower potential energy states,resulting in smaller diffusion displacements for the slow Si atoms.Concurrently,slow Si atoms tend to be in the centers of smaller clusters with coordination numbers of 9 and 10.During the isothermal relaxation process,clusters with coordination numbers 9 and 10 have longer lifetimes,suggesting that the escape of slow Si atoms from their cages is more challenging.The findings mentioned above hold significant implications for understanding the caged dynamics.
文摘目的探讨终板体积骨密度(endplate volumetric bone mineral density,EP-vBMD)对侧方入路腰椎融合(lateral lumbar interbody fusion,LLIF)术后Cage沉降的影响。方法选择2018年1月~2020年12月在本院接受LLIF手术治疗的151例患者进行回顾性分析,收集患者EP-vBMD、椎体体积骨密度(vertebral body volumetric bone mineral density,VB-vBMD)、年龄、性别、体质量指数(body mass index,BMI)、医学共病(糖尿病等)、吸烟、美国麻醉医师协会(american society of anesthesiologists,ASA)评分、查尔森共病指数(charlson comorbidity index,CCI)、手术节段、手术椎体和是否使用后路螺钉固定等资料。根据术后1年患者是否发生Cage沉降,将患者分为Cage沉降组和非沉降组,比较两组患者临床资料差异,将单因素分析P<0.2的变量进一步采用多因素Logsitic回归分析,观察EP-vBMD对终板沉陷的影响。结果Cage沉降患者的VB-vBMD和EP-vBMD水平均低于非Cage沉降患者,差异均有统计学意义(P<0.05)。Cage沉降组患者年龄高于非Cage沉降组患者,差异有统计学意义(P<0.05);Cage沉降组和非Cage沉降组患者性别、吸烟、糖尿病、后路螺钉固定等资料差异均有统计学意义(P<0.05)。多因素Logistic回归分析显示,EP-vBMD和应用后路螺钉固定均是Cage沉降的保护性因素(P<0.05)。结论低EP-vBMD是LLIF术后Cage沉降的风险因素,对患者进行LLIF时,应考虑术前EP-vBMD的测量。
文摘Flat metal strips are deformed progressively into profiles with certain geometry sections by a series of successive rotating rolls at the room temperature, and it is called the cold roll-forming. An effective method is given for roll design to avoid major defects via finite element method （FEM） simulation using a booting model. The simulation gives reasonable fit to the actual product in the two major roll-forming defects, i.e. , edge wave and springback. The redesigned rolls using the approach of multi-stand FEM simulation can effectively control these two defects.
基金This project is supported by Provincial Natural Science Foundation of Hebei (No.502214).
文摘To simulate the process of cold roll-forming process, a new method isadopted. The theoretical foundation of this method is an elastic-plastic large deformation splinefinite strip method based on object-oriented programming. Combined with the computer graphicstechnology, the visual simulation of cold roll-forming is completed and the system is established.By analyzing common channel steel, the process is shown and explained including theory method, modeland result display. So the simulation system is already a kind of mature and effective tool toanalyze the process of cold roll forming.
文摘The magnetic field generated in the air gap of the cage asynchronous machine and the harmonics of the magnetomotive forces creating that magnetic field,as well as the synchronous parasitic torques,radial magnetic forces have been discussed in great detail in the literature,but always separately,for a long time.However,systematization of the phenomenon still awaits.Therefore,it is worth summarizing the completeness of the phenomena in a single study–with a new approach at the same time-in order to reveal the relationships between them.The role of rotor slot number is emphasized much more than before.New formulas derived for both synchronous torques and radial magnetic forces are used for further investigation.It will be shown that both phenomena in subject must be treated together.Formulas will be provided to take into account attenuation.Design guide will be provided to avoid dangerous rotor slot numbers.It will be shown that the generation of synchronous torques and radial magnetic forces do not depend–in this new approach-on the slot combination,but on the rotor slot number itself.
文摘The magnetic field generated in the air gap of the cage asynchronous machine and the harmonics of the magnetomotive forces creating that magnetic field, as well as the related differential leakage, attenuation, asynchronous parasitic torques have been discussed in great detail in the literature, but always separately, for a long time. However, systematization of the phenomenon still awaits. Therefore, it is worth summarizing the completeness of the phenomena in a single study – with a new approach at the same time-in order to reveal the relationships between them. The role of rotor slot number is emphasized much more than before. An existing, commonly used, but still impractical basic figure has been modified to more clearly demonstrate the response of the rotor for the harmonics of the stator. The need to treat differential leakage, asynchronous parasitic torques and attenuation together will be demonstrated: new formula for asynchronous parasitic torque is derived;the long-used characteristic curves for differential leakage and attenuation used separately so far was merged into one, correct curve in order to provide a correct design guide for the engineers.
文摘目的:通过系统评价的方法分析影响腰椎椎体间融合术后cage后移(cage retropulsion,CR)发生的危险因素。方法:检索PubMed、Embase、Cochrane Library、Web of Science、中国生物医学文献数据库(CBM)、中国知网(CNKI)、万方数据库和维普数据库,收集各数据库建库至2023年4月有关影响腰椎椎体间融合术后CR危险因素的文献,研究类型为队列研究及病例对照研究,采用纽卡斯尔-渥太华质量评估量表(Newcastle-Ottawa scale,NOS)对纳入研究进行质量评价,提取纳入研究的基本信息,包括年龄及性别等以及CR发生相关研究因素,如骨质疏松、终板损伤、螺钉松动、梨形椎间隙、cage形状、cage置入深度及手术时长、出血量等。评价纳入研究的偏倚风险后,使用Stata14.0软件进行Meta分析。结果:共纳入16篇相关文献,其中15篇文献为回顾性病例对照研究,1篇为前瞻性队列研究,均为中等及以上质量研究,NOS评分均≥7分。总样本量12667例,其中发生CR者(CR组)326例,未发生CR者(nCR组)12341例,CR发生率为2.83%。Meta分析结果显示:性别(男性)[比值比(odds ratio,OR)=1.264,95%置信区间(confidence interval,CI)(1.003~1.593),P=0.047]、年龄[效应量标准化平均差(standardized mean difference,SMD)=0.237,95%CI(0.054~0.419),P=0.011]、骨质疏松[OR=3.126,95%CI(1.040~9.401),P=0.042]、骨终板损伤[OR=8.161,95%CI(3.711~17.945),P=0.000]、螺钉松动[OR=7.978,95%CI(3.487~18.255),P=0.000]、梨形椎间隙[OR=6.037,95%CI(2.381~15.305),P=0.000]、cage置入深度不足[OR=5.157,95%CI(1.760~15.111),P=0.003]是腰椎椎体间融合术后发生CR的危险因素。结论:性别(男性)、高龄、骨质疏松、骨终板损伤、螺钉松动、梨形椎间隙、cage置入深度不足与腰椎椎体间融合术后发生CR密切相关,随访期间应对此类患者密切观察,预防发生严重cage移位的并发症。
