碳笼负载镍基磁性催化剂Ni@Cage-C的制备与性能研究

以自然结晶法制备的ZIF-67为前驱体,采用包裹-刻蚀-碳化策略,得到大小均匀的纳米碳笼(Cage-C),再于液相条件下以碳笼为载体负载上活性金属镍(Ni),成功制备了非贵金属磁性催化剂Ni@Cage-C,并应用于对硝基苯酚催化还原反应以考察其多相催化性能。结果表明:优化条件下制备的Ni@Cage-C催化剂为碳笼包裹单质镍结构,其平均颗粒大小为550 nm;将Ni@Cage-C用于对硝基苯酚催化还原反应时,催化性能明显优于参照催化剂雷尼镍(Raney-Ni)。质量反应速率常数kM为6.11 mg^(-1)·min^(-1),催化效率达到98.87%,循环反应十圈后活性仍高于初始活性的85%。

基于MRI椎体和终板骨质量评分对经椎间孔椎间融合术后cage沉降的预测价值

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。

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疗效初探

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。

Harmonics in the Squirrel Cage Induction Motor Analytic Calculation Part III: Influence on the Torque-speed Characteristic

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.

Selective photosynthesis of Z-olefins through crystalline metal-organic cage-initiated expeditious cascade reactions

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.

Effects of anions on the structural regulation of Zn‑salen‑modified metal‑organic cage

By virtue of a 3∶1 complementary coordination strategy,a chiral heteroleptic metal-organic cage that con-tains divergent functional units,Pd‑R(Zn),was precisely constructed via self-assembly of monodentate variational Zn-salen ligands RZn and NADH(reduced nicotinamide adenine dinucleotide)mimic modified tridentate ligands with square-planar Pd ions.UV-Vis and luminescence spectra experiments reveal that different anions could selec-tively interact with different sites of Zn-salen modified metal-organic cages to achieve the structural regulation of cage compound,by using the differentiated host-guest electrostatic interactions of counter ions with metal-organic hosts.Compared to other anions,the presence of chloride ions caused the most significant fluorescence emission enhancement of Pd‑R(Zn),meanwhile,the UV-Vis absorption band attributed to the salen aromatic backbone showed an absorption decrease,and the metal-to-ligand induced peak displayed a blue shift effect.Circular dichro-ism and ^(1)H NMR spectra further demonstrate that the introduction of chloride anions is beneficial to keeping a more rigid scaffold.

Metal-organic cage as fluorescent probe for LiPF_(6)in lithium batteries

Lithium hexafluorophosphate(LiPF_(6)),the most commonly used lithium battery electrolyte salt,is vulnerable to heat and humidity.Quantitative and qualitative determination the variation of LiPF_(6)have always relied on advanced equipment.Herein,we develop a fast,convenient,high-selective fluorescence detection method based on metal-organic cages(MOC),whose emission is enhanced by nearly 20 times in the presence of LiPF_(6)with good stability and photobleaching resistance.The fluorescent probe can also detect moisture in battery electrolyte.We propose and verify that the luminescence enhancement is due to the presence of hydrogen bond-induced enhanced emission effect in cages.Fluorescent excitation-emission matrix spectra and variable-temperature nuclear magnetic resonance spectroscopy are employed to clarify the role of hydrogen bonds in guest-loaded cages.Density functional theory(DFT)calculation is applied to simulate the structure of host-guest complexes and estimate the adsorption energy involved in the system.The precisely matched lock-and-key model paves a new way for designing and fabricating novel host structures,enabling specific recognition of other target compounds.

Porous Organic Cage‑Based Quasi‑Solid‑State Electrolyte with Cavity‑Induced Anion‑Trapping Effect for Long‑Life Lithium Metal Batteries

Porous organic cages(POCs)with permanent porosity and excellent host–guest property hold great potentials in regulating ion transport behavior,yet their feasibility as solid-state electrolytes has never been testified in a practical battery.Herein,we design and fabricate a quasi-solid-state electrolyte(QSSE)based on a POC to enable the stable operation of Li-metal batteries(LMBs).Benefiting from the ordered channels and cavity-induced anion-trapping effect of POC,the resulting POC-based QSSE exhibits a high Li+transference number of 0.67 and a high ionic conductivity of 1.25×10^(−4) S cm^(−1) with a low activation energy of 0.17 eV.These allow for homogeneous Li deposition and highly reversible Li plating/stripping for over 2000 h.As a proof of concept,the LMB assembled with POC-based QSSE demonstrates extremely stable cycling performance with 85%capacity retention after 1000 cycles.Therefore,our work demonstrates the practical applicability of POC as SSEs for LMBs and could be extended to other energy-storage systems,such as Na and K batteries.

Research of caged dynamics of clusters center atoms in Pd_(82)Si_(18) amorphous alloy

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.

终板体积骨密度在侧方入路腰椎椎体间融合术后Cage沉降的预测价值

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。

鲁棒的满足误差约束的平面cage生成

Cage是基于广义重心坐标的形状编辑与变形应用的基本要素,但现有算法无法保证生成的cage与模型间的距离能够满足给定的误差约束.为此,提出一种鲁棒的平面cage生成算法,对于用户指定的平面网格模型和Hausdorff距离上界,首先生成初始cage,使其与平面网格模型边界间的双向Hausdorff距离在设定的界内;其次,通过拓扑优化和几何优化降低cage的复杂度,并保证cage满足距离上界约束.对于任意的平面网格模型,该算法能从理论上保证生成的cage满足约束.在包含大量平面网格模型的公开数据集上的实验结果表明,与现有方法相比,该算法生成的cage在相同的Hausdorff距离下顶点数更少,在相同的顶点数下Hausdorff距离更小.

腰椎椎体间融合术后cage后移危险因素的Meta分析

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。

Harmonics in the Squirrel Cage Induction Motor Analytic Calculation-Part Ⅰ: Differential Leakage, Attenuation, Asynchronous Parasitic Torques

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.

Harmonics in the Squirrel Cage Induction Motor,Analytic Calculation Part Ⅱ:Synchronous Parasitic Torques,Radial Magnetic Forces

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.

单边钉棒系统内固定联合椎间cage植骨融合治疗单侧相邻两节段腰椎间盘突出症的效果观察

目的:探讨单侧相邻两节段腰椎间盘突出症应用单边钉棒系统内固定联合椎间cage植骨融合的效果。方法:选取2016年3月—2021年2月中国人民解放军联勤保障部队第九六三医院收治的60例单侧相邻两节段腰椎间盘突出症患者作为研究对象,按照随机数表法分为两组,每组各30例,对照组采用双侧椎弓根内固定联合椎间cage植骨融合术,观察组采用单边钉棒系统内固定联合椎间cage植骨融合术,比较两组患者临床指标、疼痛程度、睡眠质量、生活质量。结果:观察组术中出血量、手术时间等临床指标均低于对照组,差异有统计学意义(t=6.004、14.203、5.018,P<0.05);术后1个月、术后3个月,观察组腿疼、腰痛疼痛评分低于对照组,差异有统计学意义(t=6.065、17.842;t=2.439、3.935,P<0.05);术后,观察组睡眠质量评分低于对照组,差异有统计学意义(t=2.802、 3.436、 2.320、 2.360、 2.281、 2.573、4.219,P<0.05);术后,观察组生活质量评分高于对照组,差异有统计学意义(t=2.517、2.618、2.113、2.176、2.716、2.413、2.133、3.749,P<0.05)。结论:单侧相邻两节段腰椎间盘突出症应用单边钉棒系统内固定联合椎间cage植骨融合术,手术时间较短,效率良好。

笼养密度对公母分饲黄羽肉鸡生长性能、免疫器官发育、抗氧化能力、肠道组织形态及免疫相关基因mRNA表达的影响

本试验旨在探讨笼养密度对公母分饲黄羽肉鸡生长性能、免疫器官发育、抗氧化能力、肠道组织形态及免疫相关基因mRNA表达的影响。选用21日龄黄脚麻鸡720只,3层层叠式笼内饲喂,鸡笼规格为长×宽×高=1.2 m×0.8 m×0.4 m,公鸡和母鸡分开饲养,均随机分为4组(每组5个重复),笼养密度分别为15(低密度组)、17(中密度组)、19(中高密度组)和21只/m 2(高密度组)。试验期42 d。结果表明:1)对于公鸡,21~42日龄时,高密度组平均日采食量显著低于低密度组和中密度组(P<0.05);43~63日龄时,中高密度组和高密度组平均日采食量显著低于低密度组和中密度组(P<0.05),中高密度组和高密度组平均日增重显著低于低密度组(P<0.05)。对于母鸡,21~42日龄时,中高密度组和高密度组平均日采食量显著低于低密度组(P<0.05),高密度组平均日增重显著低于低密度组(P<0.05);43~63日龄时,高密度组平均日采食量显著低于低密度组和中密度组(P<0.05),中高密度组平均日增重显著低于低密度组(P<0.05)。2)对于公鸡,低密度组肝脏重量显著低于其他各组(P<0.05),肝脏指数显著低于高密度组(P<0.05)。3)对于母鸡,中密度组血清超氧化物歧化酶活性显著高于高密度组(P<0.05),中高密度组血清丙二醛含量显著高于高密度组(P<0.05)。4)对于公鸡,中密度组空肠绒毛高度/隐窝深度显著高于高密度组(P<0.05)。对于母鸡,高密度组十二指肠隐窝深度显著高于中高密度组(P<0.05),中高密度组十二指肠绒毛高度/隐窝深度显著高于高密度组(P<0.05);高密度组空肠绒毛高度显著低于中密度组和中高密度组(P<0.05),高密度组空肠绒毛高度/隐窝深度显著低于低密度组(P<0.05);高密度组回肠隐窝深度显著高于其他各组(P<0.05)。5)对于公鸡,中高密度组空肠肿瘤坏死因子-α(TNF-α)mRNA相对表达量显著高于其他各组(P<0.05)。对于母鸡,中高密度组空肠核因子E2相关因子2(Nrf2)和Toll样受体4(TLR4)mRNA相对表达量显著高于低密度组(P<0.05)。由此可见,高笼养密度会对黄羽肉鸡生长性能、抗氧化能力、肠道组织形态等相关指标产生影响;笼养密度可能通过影响肠道抗氧化和免疫相关基因表达影响黄羽肉鸡肠道免疫功能。

基于多元数据的夏季鸡舍环境质量评价及其对产蛋性能的影响

蛋鸡舍环境质量直接影响蛋鸡产蛋性能。为探究夏季蛋鸡舍环境质量及其对产蛋性能的影响,研究提出基于多元数据的分析方法,首先采集鸡舍内7类关键环境因子数据,按照热环境、光环境和气体环境分组,再根据改进D-S证据理论规则进行迭代融合,得到蛋鸡舍各检测点环境质量的综合评价结果,进而分析其对产蛋性能的影响。以夏季八层层叠式蛋鸡舍为试验鸡舍开展试验。结果显示:八层层叠式蛋鸡舍下四层的环境质量和平均产蛋率的最优位置均处于鸡舍前端;平均产蛋率最差的位置处于鸡舍中端,该位置环境质量综合评价结果为一般;上四层平均产蛋率最优位置为鸡舍中端,该位置环境质量综合评价结果为适宜;平均产蛋率最差位置和环境质量最差位置均为鸡舍后端(靠近风机端)。在试验鸡舍所有检测点中,平均产蛋率高于86%的检测点,环境质量综合评价结果大都为适宜,平均产蛋率低于86%的检测点,环境质量综合评价结果为一般或差,鸡舍内各检测点环境质量综合评价结果与平均产蛋率的变化趋势高度一致。该研究为准确评价蛋鸡舍环境质量,揭示蛋鸡舍环境质量对产蛋性能的影响提供了一种行之有效的方法。

颈椎前路椎体次全切除减压融合钛笼倾斜角度与术后钛笼下沉的有限元分析

背景:颈椎前路椎体次全切除减压融合是治疗颈椎退行性疾病的常规手段,钛笼是椎体次全切后维持颈椎稳定的重要植入物,近几年临床发现,术后很多患者出现钛笼下沉等并发症,其原因存在很大争议。目的:探讨颈椎前路椎体次全切除减压融合钛笼倾斜角度与术后钛笼下沉的内在生物力学关系。方法:通过正常人体颈椎CT图像建立C_(4)-C_(6)节段三维有限元模型,在三维模型中模拟颈椎前路C5椎体次全切除减压融合,并模拟置入不同倾斜角度的钛笼(-6°至-1°称之为负角度,即钛笼前缘短于钛笼后缘为负角度;1°-6°称之为正角度,即钛笼前缘长于钛笼后缘为正角度)。在C_(4)椎体上分别施加预载荷50,100和150 N的应力作用,记录钛笼与C_(4)下终板和C_(6)上终板各个接触点的应力值(钛网接触面的各7个应力接触点),并进行统计学分析。结果与结论:①钛笼倾斜角正角度组和负角度组分别在C_(4)椎体施加50,100和150 N应力下产生的数据经Mann-Whitn检验发现,差异均有显著性意义(P<0.05);钛笼倾斜角正角度组在50,100和150 N应力条件下,其离散系数均小于负角度组;②在C_(4)椎体施加50,100和150 N应力条件下,钛笼倾斜角正角度组内Wilcoxon符号秩检验发现当角度设为1°-5°时,差异无显著性意义(P>0.05);但当钛笼倾斜角设为6°时,差异有显著性意义(P<0.05);③在C_(4)椎体施加50,100和150 N应力条件下,钛笼倾斜角负角度组内Wilcoxon符号秩检验发现当倾斜角设为-1°至-6°时,差异无显著性意义(P>0.05);④提示矢状位上,钛笼倾斜角为正角度时比倾斜角为负角度时更加稳定,更加适合临床使用;钛笼倾斜角在1°-5°区间内表现相对稳定,当倾斜角为6°时则稳定性开始下降,容易出现术后钛笼下沉的并发症,临床上根据术中情况更适合选用倾斜角度在1°-5°的钛笼,以提高疗效。

3D打印不同骨密度的椎间融合器优化设计

依据颈椎的原始数据,通过医学图像处理和逆向建模操作分别重建了颈椎C6段和C7段的模型,并将其装配形成颈椎C6~C7节段,得到椎间融合器基本数据。依据基本数据分别建立了矩形多孔、梯度多孔、八面体多孔椎间融合器模型。对融合器施加成年男性颈部所受到的最大力,通过有限元分析求解应力、应变以及最大变形量。计算设计的椎间融合器的弹性模量下降情况,对不同孔隙率的矩形多孔结构椎间融合器进行分析,并优化设计。结果可知,3种结构的融合器均有不同程度的弹性模量下降,而矩形结构椎间融合器的孔隙率在60%左右时,弹性模量下降得最多。

精密轴系低温动态摩擦力矩波动分析及优化策略

精密轴系作为机械设备旋转支承核心,其动态摩擦力矩及平稳性直接影响整机功耗及运转精度,尤其在低温环境下,由于温度对润滑油黏度、零件尺寸和配合关系的影响,精密轴系更易出现动态摩擦力矩异常波动。针对某精密轴系低温环境下批次性动态摩擦力矩异常波动现象进行了主因素分析,通过ADAMS平台建立仿真模型,分析了引导间隙、兜孔间隙对保持架动态特性的影响。结合拆解数据,指出兜孔间隙不合理引发的兜孔磨损是造成精密轴系动态摩擦力矩异常波动的原因,通过数理统计对保持架参数进行优化,兜孔间隙与引导间隙之比为0.70~0.85时,该精密轴系低温下运转稳定。