Assessment of stiffness and strength of 4 different implants available for equine fracture treatment: a study on a 20 degrees oblique long-bone fracture model using a bone substitute

OBJECTIVE: To compare the mechanical properties of 4 stabilization methods for equine long-bone fractures: dynamic compression plate (DCP), limited contact-DCPlate (LC-DCP), locking compression plate (LCP), and the clamp-rod internal fixator (CRIF--formerly VetFix). STUDY DESIGN: In vitro mechanical study. SAMPLE POPULATION: Bone substitute material (24 tubes) was cut at 20 degrees to the long axis of the tube to simulate an oblique mid-shaft fracture. METHODS: Tubes were divided into 4 groups (n=6) and double plated in an orthogonal configuration, with 1 screw of 1 implant being inserted in lag fashion through the "fracture". Thus, the groups were: (1) 2 DCP implants (4.5, broad, 10 holes); (2) 2 LC-DCP implants (5.5, broad, 10 holes); (3) 2 LCP implants (4.5/5.0, broad, 10 holes) and 4 head locking screws/plate; and (4) 2 CRIF (4.5/5.0) and 10 clamps in alternating position left and right of the rod. All constructs were tested in 4-point bending with a quasi-static load until failure. The implant with the interfragmentary screw was always positioned on the tension side of the construct. Force, displacement, and angular displacement at the "fracture" line were determined. Construct stiffness under low and high loads, yield strength, ultimate strength, and maximum angular displacement were determined. RESULTS: None of the implants failed; the strength of the bone substitute was the limiting factor. At low loads, no differences in stiffness were found among groups, but LCP constructs were stiffer than other constructs under high loads (P=.004). Ultimate strength was lowest in the LCP group (P=.01), whereas yield strength was highest for LCP constructs (409 N m, P=.004). CRIF had the lowest yield strength (117 N m, P=.004); no differences in yield strength (250 N m) were found between DCP and LC-DCP constructs. Differences were found for maximum angular displacement at the "fracture" line, between groups: LPC<DCPDCPDCP, LC-DCP, and LCP constructs provided sufficient biomechanical stability to withstand single-cycle loads that might be experienced postoperatively. LCP constructs showed the best performance because of the highest yield strength, above which irreversible deformation occurred. Inadequate biomechanical properties, excessive motion, and shape of the device create concern about the use of CRIF in these large sizes. CLINICAL RELEVANCE: CRIF does not meet the demands for equine long-bone fracture treatment. With respect to biomechanical properties, DCP, LC-DCP, and LCP constructs did not show critical differences so other factors may direct clinical selection of these implants. We prefer the LCP implants because of the high yield strength, high stiffness under high-load application, and the least movement at the fracture line.     

不同来源饲料级磷酸氢钙的质量研究

选择硫酸法和盐酸法生产的饲料级磷酸氢钙,对不同来源的饲料级磷酸氢钙的质量进行研究,包括颜色、容重、均匀度、pH、钙、总磷、游离水分的测定。结果表明:硫酸法生产的饲料级磷酸氢钙和盐酸法生产的饲料级磷酸氢钙的质量指标之间存在差异,硫酸法产品pH值高于盐酸法,而在钙含量和游离水含量上面则是盐酸法的产品高于硫酸法的产品。     

车辆电磁制动器电磁体试验台基于LabVIEW和数字电位器的调速电机控制系统设计

在以LabVIEW虚拟仪器为测控系统的车辆电磁制动器电磁体试验台上,通过数字电位器的方法实现对当前通用电磁调速电动机调速控制器转速给定电压信号的电可调节。设计了实际电路对原控制器进行改造,实测了系统的运行特性,进而为电磁调速电机的自动控制提供一种简单实用的方案。     

融合YOLOv5s与Criminisi算法的农业遥感图像去云方法研究

【目的】构建融合YOLOv5s与改进Criminisi算法的农业遥感图像去云方法,为云层干扰环境下地表信息获取、地表物的解译等研究提供支持。【方法】首先使用基于容差的暗通道先验(dark channel prior,DCP)算法去除雾和部分薄云,以提升图像整体对比度与云层边缘清晰度;然后融合YOLOv5s深度学习网络进行云层区域阈值分割,实现云层蒙版的快速精确自动提取;最后通过样本块大小自适应调整策略对Criminisi算法进行改进,实现遥感图像的有效去云修复处理。通过对含不同大小云层的遥感图像进行去云试验,并利用信息熵、峰值信噪比(peak signal-to-noise ratio,PSNR)、均方误差(mean-square error,MSE)和结构相似性(structural similarity index measure,SSIM)4个指标对去云结果进行评价,以验证本研究算法的有效性。【结果】采用融合YOLOv5s和自适应样本块的改进Criminisi算法对8幅含云图像进行了修复,修复后图像的平均PSNR为21.01,平均SSIM为0.77;并对57幅模拟加云图像进行修复,其平均PSNR为28.59,平均SSIM为0.93,表明将改进Criminisi算法应用于遥感图像去云研究是可行的。在此基础上,对本研究算法的适用性以及阴影对去云效果影响的研究表明,不同大小和位置的云层干扰造成未知区域不确定度较大,对修复效果影响较为严重;阴影区域与云区域相接时存在阴影块填充,修复效果尚有待提升。【结论】融合YOLOv5s与改进Criminisi算法的去云方法可有效修复云层遮挡区域,同时保留较为真实的地表信息,可用于农业遥感信息精细感知研究。     

不同添加水平的磷酸一二钙对肉鸡生产性能、钙磷代谢及盲肠微生物的影响

本试验旨在研究磷酸一二钙（MDCP）对AA肉鸡生产性能、血液生化指标、胫骨强度、骨骼中钙、磷代谢和盲肠微生态的影响以及在饲粮中完全替代磷酸氢钙的适宜磷酸一二钙添加水平。试验选取健康的1日龄AA肉鸡450只，随机分为5组。对照组（CK）以磷酸氢钙（DCP）补充饲粮非植酸磷，试验组以MDCP补充饲粮非植酸磷，试验1组至试验4组饲粮中非植酸磷水平分别为对照组的60%、80%、100%及120%，即T1、T2、T3和T4。每组6个重复，每个重复15只，试验期42 d。于试验第19~21天和第39~41天进行代谢试验，于第21、42天分别进行生产性能、血液、盲肠微生物等指标测定和样品采集及分析。结果表明：1）与对照组相比，不同试验组均显著提高21 d和42 d肉鸡的生产性能（P<0.05），其中试验2组欧洲指数最高；2）除试验1组钙表观代谢率外，其他3个试验组21 d钙、磷的表观代谢率显著降低（P<0.05），试验1组和试验2组42 d的钙、磷表观代谢率显著提高（P<0.05）；3）试验1组21 d胫骨的钙含量较对照组显著升高（P<0.05），磷和最大应力显著降低（P<0.05），试验3组42 d胫骨的钙和磷含量较对照组和试验1组显著提高（P<0.05），试验2组和试验3组的最大应力显著高于其他处理组（P<0.05）；4）试验1组21 d血磷含量较对照组显著降低（P<0.05），试验4组较对照组显著提高（P<0.05）；5）肉鸡盲肠微生物高通量测序结果表示，对照组和4个试验组21 d肉鸡盲肠微生物有明显差异，聚类分支距离较远，42 d肉鸡试验组的微生物多样性较对照组丰富，其多样性明显高于21 d。综合各项指标结果表明，添加MDCP磷源的量为DCP磷源量的80%时，肉鸡1~21和1~42 d的生产性能，血液、骨骼指标均能达到最佳效果，同时有助于肠道微生物的稳定和健康。     

Effects of varying dietary protein and energy supply on growth, body composition and protein utilization in gilthead seabream (Sparus aurata L.)

Diets formulated with increasing digestible energy (10–22 DE MJ kg⁻¹) contents and decreasing digestible crude protein (DCP)/DE ratios (34–15 g MJ⁻¹) were fed to triplicate groups of Sparus aurata in three consecutive trials. Fish were hand-fed to apparent satiation and voluntary feed intake was found to be dependent upon dietary DE content. Daily growth was regulated both by energy and protein intake and reached its maximum at high energy levels. Growth composition showed narrow limits regarding protein gain (157–190 g kg⁻¹) and a wider range regarding lipid (55–210 g kg⁻¹) deposition reflecting the dietary energy to protein supply. Energy utilization for growth was constant at a value of 0.50 regardless of energy intake. Efficiency of protein utilization for growth varied between 0.33 and 0.60 depending on the DCP/DE ratio in the diet. The optimal protein utilization for protein deposition was found to be at 0.47. These values allow daily energy and protein requirements for growing S. aurata to be quantified. This demonstrates that the optimal dietary DCP/DE supply changes with fish size, growth potential and daily feed intake.