Effectivity and safety of trifocal intraocular lenses and capsular tension rings implantation for cataract patients with axial high myopia

●AIM:To assess effectivity and safety of trifocal intraocular lenses(IOLs)and capsular tension rings in treating cataract patients with axial high myopia.●METHODS:A prospective nonrandomized controlled clinical trial was conducted.Totally 98 eyes(74 patients)who underwent femtosecond laser-assisted cataract surgery(FLACS)with trifocal IOLs were enrolled in the study and followed up for 2y after surgery:46 eyes(33 patients)with capsular tension ring implantation in the long axial lengths(AL)group(26<AL<29 mm)and 52 eyes(41 patients)in the normal AL group(22<AL<24.5 mm).Postoperative outcomes about effectivity and safety,including the subjective and objective visual quality,and postoperative complications were assessed.●RESULTS:Uncorrected distance visual acuity at 5 m and uncorrected intermediate visual acuity at 60 and 80 cm in the long AL group were significantly worse than those in the normal AL group at 3mo postoperatively(P<0.05).The differences in reading speed,spectacle independence and potential visual complaints between the two groups were not statistically significant(P>0.05).The dysfunctional lens index and total modulation transfer function(MTF)average height were similar between the two groups.The postoperative internal coma aberrations in the axial high myopia eyes were significantly higher than that in the normal AL group(P<0.05).The total satisfaction score in the long AL group(91.32±2.76)was slightly higher than that in the normal AL group(90.36±3.47),but there was no difference(P=0.136).A statistically negative correlation was found between corrected distance visual acuity(CDVA)and dysfunctional lens index(r=-0.382,P=0.009),and between CDVA and the total MTF average height(r=-0.374,P=0.01).But there was no significant correlation between CDVA and total satisfaction score(r=0.059,P=0.696).Postoperative complications mainly presented as posterior capsular opacity(PCO),retinal detachment and cystoid macular edema.There was no difference in the incidence of fundus disease(6.5%vs 3.8%,P=0.663)or PCO(17.4%vs 7.7%,P=0.217)between the two groups at two years.●CONCLUSION:The utilization of trifocal IOL and capsular tension ring implantation is beneficial for cataract patients with axial high myopia undergoing FLACS.This approach not only ensures excellent subjective feelings and objective visual quality,but also does not increase the incidence of postoperative complications.

Extra-Axial Anaplastic Pleomorphic Xanthoastrocytoma Mimicking Meningioma: A Case Report with Literature Review

Background: A number of meningeal neoplastic lesions may radiologically and clinically simulate meningioma, include hemangiopericytomas, solitary fibrous tumors, schwannomas, hematolymphoid lesions, metastases, and others very rarely, also may clinically mimic meningiomas. Case Description: We present the case of A 28-year-old male patient, with no notable medical history, who presented with worsening headaches for 3 months, imbalance, and visual deficits, An initial MRI revealed extra-axial lesion involving the right Parieto-occipital, The tumor was hypointense on T1-weighted MR images, hyperintense signals on T2-weightedMR images, and heterogeneously enhanced suggestive of a meningioma, total resection was achieved, and the histopathological analysis confirmed the diagnosis of an angioblastic meningioma. However, 15 months later, the patient presented with the same initial visual complaints. A subsequent MRI showed lesion recurrence, leading to a second surgical intervention. The histopathological analysis confirmed the diagnosis of an anaplastic xanthoastrocytoma. Conclusion: This represents an unusual location for an anaplastic pleomorphic xanthoastrocytoma, which should broaden the differential diagnosis of extra-axial lesions.

Experimental investigation of axially loaded steel fiber reinforced high strength concrete-filled steel tube columns

An experimental study on the compressive behavior of steel fiber reinforced concrete-filled steel tube columns is presented. Specimens were tested to investigate the effects of the concrete strength, the thickness of steel tube and the steel fiber volume fraction on the ultimate strength and the ductility. The experimental results indicate that the addition of steel fibers in concrete can significantly improve the ductility and the energy dissipation capacity of the concrete-filled steel tube columns and delay the local buckling of the steel tube, but has no obvious effect on the failure mode. It has also been found that the addition of steel fibers is a more effective method than using thicker steel tube in enhancing the ductility, and more advantageous in the case of higher strength concrete. An analytical model to estimate the load capacity is proposed for steel tube columns filled with both plain concrete and steel fiber reinforced concrete. The predicted results are in good agreement with the experimental ones obtained in this work and literatures.

Accuracy of axial length measurements from immersion B-scan ultrasonography in highly myopic eyes

AIM:To evaluate the accuracy of axial length(AL)measurements obtained from immersion B-scan ultrasonography(immersion B-scan)for intraocular lens(IOL)power calculation in patients with high myopia and cataracts.METHODS:Immersion B-scan,contact A-scan ultrasonography(contact A-scan),and the IOLMaster were used to preoperatively measure the AL in 102 eyes from 102 patients who underwent phacoemulsification and IOL implantation.Patients were divided into two groups according to the AL:one containing patients with22 mm≤AL【26 mm(group A)and the other containing patients with AL≥26 mm(group B).The mean error(ME)was calculated from the difference between the AL measurement methods predicted refractive error and the actual postoperative refractive error.RESULTS:Ingroup A,ALs measured byimmersion Bscan(23.48±1.15)didn’t differ significantly from those measured by the IOLMaster(23.52±1.17)or from those by contact A-scan(23.38±1.20).In the same group,the standard deviation(SD)of the mean error(ME)of immersion B-scan(-0.090±0.397 D)didn’t differ significantly from those of IOLMaster(-0.095±0.411 D)and contact A-scan(-0.099±0.425 D).In group B,ALs measured by immersion B-scan(27.97±2.21 mm)didn’t differ significantly from those of the IOLMaster(27.86±2.18 mm),but longer than those measured by Contact A-scan(27.75±2.23 mm,P=0.009).In the same group,the standard deviation(SD)of the mean error(ME)of immersion B-scan(-0.635±0.157 D)didn’t differ significantly from those of the IOLMaster(-0.679±0.359 D),but differed significantly from those of contact A-scan(-0.953±1.713 D,P=0.028).CONCLUSION:ImmersionB-scanexhibitsmeasurement accuracy comparable to that of the IOLMaster,and is thus a good alternative in measuring AL in eyes with high myopia when the IOLMaster can’t be used,and it is more accurate than the contact A-scan.

Comparison axial length measurements from three biometric instruments in high myopia

AIM： To compare the axial lengths （ALs） measured with Lenstar, IOLMaster and A-scan contact ultrasound （Ultrasound） in normal and high myopia （HM）. METHODS： Eighty-four normal eyes and 49 HM eyes were included. Three consecutive measurements were performed on each eye in the following order： Lenstar, IOLMaster, and Ultrasound. The repeatabilities of the AL measurements for each instrument were assessed by calculating the pooled coefficients of variation （CVs） of 18 eyes in each group. Comparisons between the HM and normal groups were made with independent sample t-tests. The inter-device agreements were evaluated with Bland-Altman analyses and paired two-tailed t-tests. RESULTS： For normal group, the CVs of the AL measurements taken with the Lenstar, IOLMaster and Ultrasound were 0.001%, 0.01% and 0.14%, respectively. The corresponding CVs for the HM group were 0.005%, 0.02% and 0.15%, respectively. There was significant difference between the Lenstar and the IOLMaster in normal group （P=0.031） but not in HM group （n=0.100）. In the two groups, the Lenstar and the IOLMaster produced higher values than did the Ultrasound （all P〈 0.001）. All three instruments exhibited good agreement in terms of AL values. For the intraocular lens （IOL） power calculation using SRK II formula, the Lenstar and the IOLMaster showed 0.5 D higher than Ultrasound in both groups （all P〈0.001）. No significant difference existed between the Lenstar and the IOLMaster for the IOL power calculation in both normal （n=0.474） and HM group （P= 0.103）. CONCLUSION： The three devices exhibited excellent intra-visit repeatabilities in the AL measurements. The AL and IOL power difference between partial coherence interferometry and ultrasound instruments should be noticed.

Numerical and Experimental Investigation of High-efficiency Axial-flow Pump

The experimental investigation of axial-flow pump has been rapidly developed to meet the needs of South-to-North Water Diversion Project of China. Owing to the boundary conditions of hub, blade tip clearance, much of the physical phenomena and laws involved in this complex flow field can＇t be fully determined. The flow characteristics of the high efficiency axial-flow pump have been simulated by RNG k-e turbulence model and SIMPLEC arithmetic based on FLUENT software. Numerical results indicate that the data from the prediction show agreement with the experimental results, static pressure on pressure side of blades increases slightly at circumferential direction with radius increasing, and keep almost constant at the same radial while increasing gradually from inlet to exit on the suction side along flow direction at design conditions. The static pressure, total pressure and velocity at inlet, impeller outlet and vane outlet were measured by a five-hole probe, and a contrastive experiment was done to investigate the influence of hub leakage. The experimental results show that inlet flow is almost axial and the prerotation is very small at various conditions. The meridional velocity and circulation distribution are almost identical at impeller outlet at design conditions due to steady flow and high efficiency. The residual circulation exits at downstream of the guide vane, and the circumferential velocity component increases linearly from hub to tip at small flow rate conditions. Hub leakage in adjustable blades results in the decrease of the meridional velocity and circulation at blade exit near hub. The results of numerical simulation and experiments supply important flow structure information for the high-efficiency axial-flow pump.

Seismic ductility of very-high-strength-concrete short columns subject to combined axial loading and cyclic lateral loading

The seismic ductility of reinforced very-high-strength-concrete (VHSC) short columns was studied by combinatively applying axial load and low cyclic lateral load on specimens to simulate seismic impact. Twelve specimens with concrete compressive strength ranging from 95.6 MPa to 118.6 MPa and a shear-span ratio of 2.0 were tested for shear failure pattern and fear force-displacement hysteretic responses. Combinative application of axial load and low cyclic lateral load to VHSC short columns incurs shear failure. The displacement ductility is much smaller when the axial load ratio is larger;whereas a larger stirrup ratio is accompanied with a better displacement ductility. The relationship of displacement ductility factor, μ?, with stirrup characteristic value, λv, and test axial load ratio, nt, is μ?=(1+8λv)/(0.33+nt). By this relationship and relevant codes for aseismatic design, the axial load ratio limits for aseismatic design of reinforced VHSC (C95 to C100) short columns for frame construction are respectively 0.5, 0.6, and 0.7 for seismic classes I, II, and Ⅲ;corresponding minimum characteristic values of stirrups are calculated according to the required characteristic values of at least 1.273 times of experimental results. These data are very useful to aseismatic engineering.

Change in foveal position based on age and axial length in high myopic eyes

AIM：To evaluate the influence of age and axial length（AL） on the position of the fovea in patients with high myopia（HM）.METHODS：In this prospective study,96 patients（186 eyes） with HM were consecutively recruited from the Third Affiliated Hospital of Nanchang University.DRI-OCT Atlantis,fundus imaging,and IOL Master were used in this study.Three indices were measured：the distance between the fovea and the optic nerve head（ONH） center（DFO）,the vertical distance between the fovea and the horizontal line pass of the ONH center（VDFO）,and the horizontal distance between the fovea and the vertical line pass of the ONH center（HDFO）.These measurements were used to analyze the effects of different age groups（A1,A2,A3 groups） and AL（AL1,AL2,AL3,AL4 groups） on these indices.RESULTS：The results showed that there was no statistical significance in DFO among the age and AL groups（F=0.46,0.37;P=0.62,0.76,respectively）.In HDFO,there was also no statistical significance among the age and AL groups（F=0.10,0.48;P=0.90,0.69,respectively）.In VDFO,however,the difference in the age and AL groups was statistically significant（F=3.21,3.12;P=0.04,0.02,respectively）.Thus,VDFO were correlated with age and AL（r=0.21,0.23,all P〈0.01）,while HDFO and DFO were not correlated with age and AL（r=0.30,P〉0.05）.CONCLUSION：In high myopia,the foveal position changes mainly in the vertical direction along with factors of age and AL.

Real-time measurement of high rotational projectile axial acceleration based on 2-axis acceleration sensor

The real-time measurement principle of high rotational projectile＇s angular velocity based on 2-axis acceleration sensor and the axial acceleration measurement error caused by the installation error are discussed.The 2-axis acceleration sensor is applied to measure the high rotational projectile＇s angular velocity and the measurement value of axial acceleration,the axial acceleration of the high rotational projectile equals the measurement value of axial acceleration subtracting the centrifugal acceleration component,so that the high-accuracy real-time measurement of axial acceleration is realized.The memory test has confirmed the strike tally of the theoretical analysis and the test result.The measurement technique can satisfy the high-accuracy measurement of the high rotational projectile axial acceleration in the self-determination course correction fuze projectile.

基于声发射的高强混凝土轴拉与劈拉损伤演化特征

本研究对抗压强度约100 MPa的高强混凝土开展了轴拉和劈拉应力-应变全曲线试验,比较分析了两种试验全过程声发射特征,揭示了高强混凝土轴拉和劈拉破坏机制及损伤模式演化规律。研究表明:轴拉试样在峰值应力后受宏观裂缝不稳定扩展影响易发生偏心受拉,劈拉试样在峰值应力后应变分布较均匀,裂缝扩展较稳定;轴拉试样累计声发射撞击曲线在峰值应力处呈下凸型,而劈拉试样受局部集中应力影响累计声发射撞击曲线呈上凸型;轴拉试样受拉伸应力主导发生破坏,劈拉试样的破坏经历了拉剪混合破坏到拉伸破坏的转变。

高速轴向柱塞泵空化机制研究与优化

为降低高速轴向柱塞的空化程度,以某型号轴向柱塞泵为例,利用Pumplinx软件搭建CFD仿真模型,探究不同转速与不同吸油口压力对泵空化程度的影响,并结合MATLAB软件对离散的仿真结果进行拟合,得到转速、吸油口压力与吸油效率的变化规律曲线。研究结果表明:当柱塞腔内气体体积达到12%以上,柱塞泵吸油效率下降甚至无法吸油;通过提高吸油口压力可以有效降低柱塞腔的空化程度,提高柱塞泵吸油效率;为了保证泵在5000~6000 r/min下能够正常吸油且有较高的吸油效率,可以使吸油口压力值介于0.25~0.30 MPa之间,此时柱塞腔空化程度和吸油效率均达到相对稳定。

半直驱MW级轴向磁通永磁风力发电机电磁设计与分析

在大功率直驱式风力发电机设计中,针对轴向磁通永磁发电机径向尺寸大、后期维护成本高的问题,文章将轴向磁通永磁发电机设计为大功率半直驱式风力发电机。以2 MW半直驱轴向磁通永磁发电机为研究对象,研究其参数设计原则和方法。通过探究不同极对数对发电机输出性能的影响,确定满足设计目标的发电机优选方案。采用3D有限元分析法对发电机空载和额定负载工况下的气隙磁密、电压、电流波形以及输出功率、损耗和效率进行分析,验证发电机电磁设计的正确性,发电机效率可以达到97.79%,具有损耗小、效率高的优点。通过与现有发电机进行对比,文章所提出的半直驱MW级轴向磁通永磁发电机径向尺寸显著减小,且在轴向尺寸和齿槽转矩方面比现有径向磁通结构的大功率半直驱永磁发电机表现更优。

玻璃纤维增强聚合物管约束高强混凝土柱轴压试验研究

为研究玻璃纤维增强聚合物管约束高强混凝土柱的轴压性能,设计了6个不同长细比的试件并对其进行了轴心受压试验,分析了其破坏过程及破坏形态、承载力、位移、荷载-位移曲线、骨架曲线、荷载-应变曲线。研究表明:玻璃纤维增强聚合物管约束混凝土柱轴压承载性能优异,随着长细比的减小,试件的轴压承载力提升显著;加载后期,该组合结构的破坏模式为玻璃纤维增强聚合物管发生环向破坏,内部混凝土被压溃;玻璃纤维增强聚合物空管轴压承载力相对较低,破坏时脆性特征明显;随着长细比的减小,玻璃纤维增强聚合物管约束高强混凝土柱的承载力和刚度逐步增加,长细比对结构的承载能力影响显著。研究结果对玻璃纤维增强聚合物管约束高强混凝土柱的理论研究和工程应用具有一定的指导意义。

定子通风槽钢结构对提高中型高压电机散热性能分析

为降低YJK450-6、400kW中型高压电机的通风散热性能,本文对该电机不同通风槽钢结构进行了散热性能研究。首先,在现有电机的直线标准型通风结构基础上,提出单列缩放型、双列直线型、双列缩放型3种轴-径向混合通风结构形式;在SpaceClaim软件中建立电机3维温度场数值计算模型,根据基本假设和边界条件结合电机内部热量传递公式计算出电机仿真设置参数,并导入Fluent软件进行仿真模拟,其中,计算温度场所用热源通过AnsoftMaxwell平台计算的电机损耗值获取。其次,通过网格无关性和温升试验验证本文建立的电机3维温度场数值计算模型;通过仿真模拟对比分析3种轴-径向混合通风结构与直线标准型结构对电机流场和温度场的影响;采用正交试验法对轴-径向混合通风结构进行参数优化,得到最佳散热结构和参数方案;进一步探究冷却风速对双列缩放型槽钢的电机换热性能的影响;结合定子绕组温升和电机整体的温升均匀性系数,对最佳散热结构和参数方案电机进行散热效果评价。仿真结果表明:本文建立的计算模型是有效的;双列缩放型通风槽钢结构的各项散热性能指标均最好,是最优通风槽钢结构;径向风道高度为6mm且数量为13的双列缩放型通风槽钢结构为最佳散热结构和参数方案;双列缩放型通风槽钢结构两侧的平均对流换热系数随冷却风速增大而增大,且槽钢迎风面的平均对流换热系数明显大于背风面;径向风道高度为6mm且数量为13的双列缩放型通风槽钢结构电机的内/外层绕组温升分布均匀性系数比直线标准型电机分别提高88.13%、20.11%。因此,优化设计通风槽钢结构有利于电机内部空气流动和散热,可实现有效降低电机内部温升的目的。

轴力对预应力高强混凝土管桩抗震性能的影响

目的研究轴力和往复荷载作用下预应力高强混凝土管桩的抗震性能,为预应力高强混凝土管桩的设计和实际工程应用提供参考依据。方法应用ABAQUS有限元软件对预应力高强混凝土管桩进行有限元模拟,并与已有试验结果对比,两者吻合良好,验证了模型的准确性。在此基础上,研究轴压比和有无普通钢筋及普通钢筋直径对预应力高强混凝土管桩滞回曲线、骨架曲线、刚度退化、延性及耗能能力的影响。结果配置普通钢筋可以提高预应力高强混凝土管桩的承载能力和延性,对刚度影响不大;随着轴压比的增加,预应力高强混凝土管桩的承载能力逐渐提高,但延性变差,轴压比为0.45时,预应力高强混凝土管桩发生脆性破坏。结论配置普通钢筋可以有效改善预应力高强混凝土管桩的抗震性能,预应力高强混凝土管桩的轴压比不宜超过0.3。

高温后预损伤混凝土的轴压试验研究

对不同预损伤程度下C30混凝土试件进行了高温(200、350、500℃)后轴心抗压试验,获取了试件的应力-应变全曲线,分析了高温对预损伤试件的质量损失率、峰值应力、峰值应变、弹性模量等的影响。结果表明:在相同温度下,预损伤程度越高的混凝土试件破坏越早;在相同预损伤程度下,高温温度越高,试件破坏越早;与温度相比,预损伤程度对试件轴压破坏的影响更大;各试件的质量损失率随着温度的升高而增加;预损伤程度越高,高温温度越高,试件的轴心抗压强度越低;随着温度的升高,各试件的峰值应力降低,峰值应变增加,上升段的斜率变小;各试件的弹性模量均随着温度的升高而降低。

高轴压比下小剪跨比剪力墙的抗震性能试验研究

通过5片不同轴压比下小剪跨比剪力墙构件的低周反复荷载试验,研究了高轴压比对小剪跨比剪力墙的破坏模式、受剪承载力、延性、刚度特征及耗能能力的影响,并对加载全过程中剪力墙腹板双向钢筋的受力情况及传力机制进行分析。研究结果表明:所有构件均发生了剪切破坏,并在高轴压力作用下发生了平面外的错动;高轴压比阻碍了裂缝的产生及发展,提高了构件的受剪承载力,但在构件达到峰值荷载后,强度和刚度退化剧烈,极限位移小,提高边缘约束构件配箍率可以有限地提高构件的变形能力、延性及耗能能力,但对破坏模式、传力机制的影响不大。轴压比对构件的传力机制有着显著的影响,当轴压比较小时,桁架作用明显,水平钢筋与竖向钢筋对受剪承载力的贡献相当,均能充分发挥作用;当轴压比较高时,拱作用明显,水平钢筋未能充分发挥作用,对受剪承载力的贡献有限,竖向钢筋主要对拱作用有贡献。

高强型钢超高性能混凝土短柱轴压性能试验及其有限元分析

为研究高强型钢超高性能混凝土短柱的轴压性能,对试件进行了轴心受压试验,设计参数包括配钢率、箍筋间距和箍筋形式。观察了试件的轴压破坏过程,获得了破坏形态及轴向荷载-位移曲线,分析了承载能力、变形能力、刚度等轴压性能指标,以及超高性能混凝土、纵筋、箍筋和型钢的应变发展规律。在试验研究基础上,采用ABAQUS建立了高强型钢超高性能混凝土短柱轴压性能有限元分析模型,计算结果与试验结果吻合较好,进而进行了参数分析。结果表明:试件发生的是典型轴压破坏,中部表面出现“锯齿形”裂缝;轴向荷载-位移曲线会出现2次荷载峰值;箍筋间距减小时,试件的承载能力和变形能力均提高,但刚度退化速率没有显著变化;配钢率增大时,试件的承载能力提高,变形能力先增大后减小,刚度退化变缓;型钢强度增大时,试件的承载能力和变形能力均提高,提高速度先快后慢;超高性能混凝土抗压强度增大时,试件的承载能力提高,变形能力降低;超高性能混凝土受拉能够达到峰值应变;纵筋在极限点之前发生受压屈服;箍筋在极限点时应变不足屈服应变的1/3,但在破坏点前达到受拉屈服;型钢翼缘在极限点前后发生屈服,腹板屈服晚于翼缘。

内置工字型CFRP型材高强圆钢管高强混凝土轴压短柱组合效应分析

目的 研究内置工字型CFRP型材的高强圆钢管高强混凝土短柱在轴心压力作用下三种材料的组合效应。方法 采用有限元分析软件ABAQUS对其进行数值模拟,通过相关试验验证模型的准确性,并对典型构件的破坏形态、受力全过程曲线进行分析,揭示构件各组成部分之间的相互作用和工作机理,评估CFRP配置率、钢材屈服强度、混凝土抗压强度、约束效应系数对组合效应的影响。结果 在高强圆钢管高强混凝土柱中内置CFRP型材,对构件的延性及安全裕度有显著提高,并改善了高强圆钢管对高强混凝土的约束,提高了构件的组合效应。结论 CFRP配置率控制在5.9%~8.4%,约束效应系数在1.2~1.4,钢材屈服强度不大于770 MPa时,构件中三种材料组合效应最佳。

热-湿-力耦合作用对高温后方钢管混凝土短柱轴压力学性能影响试验研究

火灾发生时钢管混凝土内部会产生水蒸气,为探讨热-湿-力耦合作用对高温后方钢管混凝土轴压力学性能的影响,进行了10根高温后方形钢管混凝土短柱轴压力学性能试验,研究排气孔数量、布置位置、轴压比和升温时间等参数对其破坏形态、轴压刚度与剩余承载力等力学性能的影响。试验结果表明,试件破坏形态表现为压溃破坏;在其他参数相同的情况下,与升温前相比,随着排气孔数量从2个增加至4个和6个,轴压刚度分别降低了69.1%、73.3%、76.4%,剩余承载力分别降低了15.8%、16.2%、21.7%。轴压刚度随轴压比的增大而降低;随着升温时间的延长,剩余承载力先随轴压比的增大而增大,后随轴压比的增大而减小。研究结果可为钢管混凝土柱的抗火设计和该类结构火灾后的损伤评估与加固提供参考。