Manufacture and Cytotoxicity of a Lead-free Piezoelectric Ceramic as a Bone Substitute—Consolidation of Porous Lithium Sodium Potassium Niobate by Cold Isostatic Pressing

Aim The piezoelectric properties and cytotoxicity of a porous lead-free piezoelectric ceramic for use as a direct bone substitute were investigated. Methodology Cold isostatic pressing （CIP） was applied to fabricate porous lithium sodium potassium niobate （Li0.06Na0.5K0.44） NbO3 specimens using a pore-forming method. The morphologies of the CIP-processed specimens were characterized and compared to those of specimens made by from conventional pressing procedures. The effects of the ceramic on the attachment and proliferation of osteoblasts isolated from the cranium of 1-day-old Sprague- Dawley rats were examined by a scanning electron microscopy （SEM） and metbylthiazol tetrazolium （MTT） assay. Results The results showed that CIP enhanced piezoelectricity and biological performance of the niobate specimen, and also promoted an extracellular matrix-like topography of it. In vitro studies showed that the CIP-enhanced material had positive effects on the attachment and proliferation of osteoblasts. Conclusion Niobate ceramic generated by CIP shows a promise for being a piezoelectric composite bone substitute.

Linde Type a Zeolite and Type Y Faujasite as a Solid-Phase for Lead, Cadmium, Nickel and Cobalt Preconcentration and Determination Using a Flow Injection System Coupled to Flame Atomic Absorption Spectrometry

In this work, a flow injection analysis (FIA) method for the trace determination of lead, cadmium, nickel and cobalt in natural waters by formation of neutral chelates with ammonium pyrrolidine dithiocarbamate (APDC) was developed. The neutral chelates formed was retained in a mini-column packed with Linde type A zeolite (LTA) and type Y Faujasite zeolite (FAU) and then eluted with methyl isobutyl ketone (MIBK) to flame atomic absorption spectrometry (EAA) for its detection. Physicochemical characterization of this zeolite was carried out by Fourier Transform infrared spectroscopy and attenuated total reflectance (FTIR and IR-ATR), scanning electron microscopy and energy dispersive X-ray microanalysis (SEM-EDX) and X-ray power diffraction (XRD). Then, a FIA configuration was used with a column preconcentration system coupled to the detection system at room temperature (22?C). The detection limit and the relative standard deviation for 5 determinations of different solutions of Pb2+, Co2+, Ni2+ and Cd2+ for FAU and LTA zeolite were calculated. The sampling frequency ranged from 18-35 h-1 and preconcentration factors from 21-250 were achieved, for a sample volume of 6 mL using 20 mg of sorbents, indicating a high retention of the analytes on the zeolites material. The recoveries obtained in natural waters samples were close to 100% for all ions metal using synthetic zeolites, confirming the applicability of the method. The isotherm models of Langmuir, Scatchard, Freundlich and Dubinin-Radushkevich were used to study the equilibrium data, indicating that successfully followed the Freundlich and Dubinin-Radushkevich (D-R) isotherms at low metal ion concentration. The Freundlich parameter n varied between 0.35-1.01, whereas D-R isotherm yields the sorption free energy E 8 kJ.mol-1 indicating psysisorption.

Sn60Pb40 solder powders produced by the planar flow casting atomization process

Conventional planar flow casting(PFC) is one of rapid solidification processes for the fabrication of microcrystalline or amorphous ribbons.Based on the conventional PFC process,the planar flow casting atomization(PFCA) process has been developed,which is a new rapid solidification process for the production of metal powder directly from alloy melts.A prototype experimental apparatus was designed and manufactured.With the apparatus,Sn60Pb40 alloy solder powders were prepared,and the effects of the main technological parameters on the powder size distribution and morphology were experimentally studied.The experimental investigations indicate that the metal powders produced by the PFCA process can be classified by velocity;and fine spherical tin-lead alloy solder powders can be fabricated by adjusting the technical parameters.The new PFCA process has such features as high productivity and efficiency,low energy consumption,simple operation,short technological process,and large gross yield.

Industrial flow of lead in China

The rules on industrial flow of lead were studied for theoretical foundation of nonrenewable resource conservation and environmental improvement. A model of lead flow in lead product life cycle was developed through lead flow analysis and was used to analyze the relationship between lead product system and its environment, thus the rules on industrial flow of lead were obtained. The results show that increasing eco-efficiency will favor both resource conservation and environmental improvement. Several indices were proposed to evaluate the lead flow. As for application, the lead-flow for China in 1999 was analyzed and the reasons for low eco-efficiency were identified. In the end, some countermeasures were proposed to improve eco-efficiency, and the future lead ore consumption and environment quality were forecasted.

Orthogonal tests of lead-clad tin bimetal continuous casting by air pressure core-filling

To provide theoretical basis and practical guidance for preparing composite rods of external diameter no larger than 12 mm by directly continuous casting,low melting point materials of lead and tin were selected to prepare composite rods of external diameter 12 mm and inner diameter 8 mm with air pressing core filled continuous casting process.The orthogonal tests consisting of three factors and three levels were designed to investigate the parameters of melting lead temperature,continuous casting speed and air pressure that affect the performance of the composite rods.The results show that melting lead temperature is the most important factor that influences the solid/liquid interface location;continuous casting speed is the most important factor that influences the surface quality and lead and tin inter-diffusion amount;air pressure can improve the surface quality obviously and make the rods easily drawn out,but the surface quality cannot get obvious improvement when the air pressure is above 0.03 MPa.The composite rods have excellent surface quality,obvious intermediate layer,even thick clad,and metallurgical bonding interface under the condition of melting lead temperature of 375 °C,continuous casting speed of 10 mm/min,and air pressure of 0.03 MPa.

虚拟现实技术在成人心肺复苏培训中应用的范围综述

目的对虚拟现实(virtual reality,VR)技术在成人心肺复苏(cardiopulmonary resuscitation,CPR)培训中的应用进行范围审查,以识别VR技术干预的内容要素和应用效果。方法以乔安娜布里格斯研究所范围综述指南为方法学框架,检索PubMed、Embase、CINAHL、Web of Science、Cochrane Library、中国知网、万方和中国生物医学文献数据库,检索时限为建库至2023年8月31日,对纳入文献进行汇总和分析。结果共纳入15篇文献,VR技术干预的内容要素包括实施CPR的意愿、反应、自我效能、按压频率、按压深度、无血流时间、复训时间、时间成本;结局指标类型为心理指标、胸外按压的质量指标、经济指标。结论VR技术在成人CPR培训中具有良好的应用前景,在心理、胸外按压质量、经济等方面的效果还可进一步挖掘。未来可基于面对面培训联合数字化反馈装置,最大化发挥VR技术的优势,形成一套综合干预策略和创新的培训模式,以进一步提高CPR培训的整体成效。

极板凹凸排布对微流通道流动性能影响研究

目前电解单元极板多采用球凸球凹的组合布置形式,其目的是为了增强通道内部的抗扰动能力,提高流体分布的均匀性。为更深入改进通道内流场分布,采用CFD数值模拟的方法对比了5种不同球凸球凹排布方式内部的流场分布特性。结果表明,5种组合布置形式在入口处均呈涡旋运动的特点,且case A方形扩列在入口处的涡旋运动范围较小;布置的形式会影响流场的分布,在球凹球凸单元间形成连续的低速尾迹区,形成较大的速度梯度;温度场的分布与流体速度分布大体呈负相关;所有通道均有速度分量uw的负速度区域,其对应湍流动能较大;通道内部的凹凸单元布置形式会影响局部流动细节,改善流场分布均匀性,其中case A方形顺列的内部流场均匀性最佳。

燃料组件堵流工况下铅铋-氩气两相流的传热压降特性分析

带绕丝燃料组件的堵流事故是铅冷快堆安全分析的重要工况之一。由于在铅铋自由液面处的气体夹带或在气体增强自然循环条件下存在铅铋-氩气的两相流情况,可能引起燃料组件堵流工况下的局部热工水力特性变化。本文通过计算流体力学软件Fluent,对带绕丝19棒束燃料组件进行建模,模拟分析了堵流工况下的铅铋-氩气两相流传热压降特性,并对两相流模型进行了对比验证,对入口雷诺数、堵块孔隙率、氩气气泡直径等因素进行参数敏感性分析。结果表明:在堵流条件下氩气气泡的流动行为包括逃逸、耗散和受限,在气相体积分率较高的区域会产生局部微正压及过热现象。研究结果可为铅冷快堆堵流事故的安全分析提供参考。

局部凸起在V形钝前缘模型中的降热特性研究

三维内转式进气道的唇口结构通常存在复杂的激波干扰及严酷的气动热载荷,严重威胁高超声速飞行器的性能与安全.在6.0马赫的高超声速流动中,以V形钝前缘模型为研究对象,设计了局部凸起的被动流动控制降热方案.采用数值模拟手段,首先研究了局部凸起方案的降热能力以及降热原理,然后初步优化了局部凸起的位置、高度以及宽度等关键设计参数,最后分析了优化后的局部凸起方案的攻角、侧滑角及马赫数的适用性.研究结果表明:上游凸起边缘形成的斜激波与主马赫反射结构形成的透射激波发生干扰,能够减弱其冲击壁面的强度,实现降热的目的;驻点凸起通过改变超声速射流的对撞角度,能够降低其对撞的强度,实现降热的目的.原始方案的降热能力约为37.75%,在对局部凸起的关键设计参数进行初步优化后,优化方案的降热能力将提升至44.60%.设计工况下的优化方案具有良好的攻角适用性,而高度可变的优化方案可以较好地适用于有侧滑角及高马赫数的流动.在研究范围内,高度可变的优化局部凸起方案的降热能力均高于20%.

铅精矿侧吹熔炼气-液多相流动过程数值模拟

铅精矿富氧侧吹熔池熔炼技术具备原料适用范围广、炉体使用寿命长、废热废料利用率高、热量有效利用率高等诸多特点,在炼铅工艺中占有重要地位。基于VOF多相流模型与Realizable k-ε湍流模型建立了侧吹炉内的多相湍流流动过程数值仿真模型,并利用物理模型对仿真可靠性进行了验证。模拟研究了喷枪喷气速度、喷嘴排布方式以及渣液位高度对熔池搅拌效果的影响,确定了喷枪结构不变的情况下,最佳的工艺条件为喷枪喷气速度100~150 m/s、渣液位高度1.6~1.7 m。

“Click”运动高升力机制

研究了具有“Click”运动的模型翼在三维流场中的气动特性.采用计算流体力学方法求解三维非定常不可压缩Navier-Stokes方程,对比了简谐和“Click”运动所产生的升力与阻力,研究了升力最大时的前缘涡特性和展向流动.结果表明,在下拍过程的升力最大处,“Click”和简谐运动的前缘涡能够分别维持至翼展的80%和60%处.两种运动都会在翼展方向存在维持展向流动的压力梯度,而“Click”运动具有更显著的展向压力梯度,对展向涡度的能量输运效率更高,因此其前缘涡能够保持更完整的形态.在上拍过程中,两种运动的前缘涡形态差异不明显,“Click”运动快速上拍的运动特点使其能够快速地摆脱尾涡的干扰,从而维持升力.

子午流注择时揿针疗法预防非小细胞肺癌患者化疗后骨髓抑制的效果研究

背景骨髓抑制是肺癌化疗常见的不良反应之一,针对化疗相关性骨髓抑制,现代医学多采用对症治疗,但存在一定局限性。目的探讨“子午流注”理论指导下择时揿针疗法预防肺癌化疗后骨髓抑制的效果。方法选择2020年7月—2022年6月在江苏省苏北人民医院呼吸科住院的142例首次行化疗的非小细胞肺癌(NSCLC)患者,按事先电脑生成的随机数字表和制订的分配方案,根据入院时间将研究对象随机分为对照组(47例)、揿针组(48例)及择时组(47例)。对照组给予肺癌化疗常规护理措施,揿针组在对照组措施基础上加用膈俞穴、脾俞穴、胃俞穴等穴位揿针疗法,择时组在对照组遵循子午流注纳子法于当日辰时(7:00—9:00)至巳时(9:00—11:00)实施择时揿针疗法。检测分析三组化疗前1 d及化疗第3、7、14、21天反映骨髓抑制情况的血常规指标及舒适度评分的变化情况。结果白细胞计数、中性粒细胞计数:揿针组和择时组化疗第7、14天均高于对照组(P<0.05),择时组均高于揿针组(P<0.05);血小板计数:化疗第7、14天揿针组和择时组均高于对照组(P<0.05)。舒适度评分:化疗第7、14天揿针组和择时组均高于对照组(P<0.05),化疗第14天择时组高于揿针组(P<0.05)。结论子午流注择时揿针疗法能有效预防NSCLC患者化疗后骨髓抑制,提高白细胞计数、中性粒细胞计数和血小板计数等部分血常规指标,提升患者的舒适度。

小翼羽掠角对机翼增升效果的影响

鸟类会通过抬起其翅膀前缘3至4根长度较短的羽毛(小翼羽)来抑制失速和增加升力,并根据不同飞行状态改变小翼羽与翅膀之间的掠角。为应对大迎角下的机翼失速问题,本文结合风洞测力和粒子图像测速实验研究了小翼羽掠角对机翼增升效果的影响。风洞测力实验结果表明,相比于无前掠的小翼羽,适当前掠的小翼羽对机翼的增升效果更好且不会增加机翼阻力。平面粒子图像测速和体视粒子图像测速实验表明,适当的前掠角能够增强小翼羽产生的前缘涡的强度,并扩大前缘涡增升的有效机翼迎角范围,最终导致适当前掠的小翼羽对机翼的增升效果更好。

X荧光光谱法测定有机肥中的金属元素砷、铬、铅

为了快速、准确地分析有机肥中砷、铬、铅的含量,更好地为农业土壤污染防治服务,营造一个健康的农业生态环境,保证农产品的安全性。采用X荧光光谱法测定有机肥中的砷、铬、铅,测定结果中砷、铬、铅的精密度(RSD)分别为2.5%~6.2%、2.6%~5.6%、3.4%~7.8%;方法检出限分别为0.5 mg/kg、3.3 mg/kg、Pb为1.8 mg/kg,其满足质量规范要求。与标准NY 525—2021作方法比对,数据一致性好,可靠。充分解决了操作繁琐、测定周期长、精密度差、成本高、污染环境等问题,值得研究借鉴,具有一定的应用推广价值。

高压压榨和风穿流压滤脱水技术试验研究与应用

采用2种半工业机型对高压压榨和风穿流这2种新型压滤脱水技术,分别开展了不同运行参数下的浮选精煤和煤泥压滤脱水规律研究。研究结果表明,物料为高硫浮选精煤和高硫煤泥时,风穿流机型比高压压榨机型的产品水分分别降低了5.51%、3.63%。采用高压压榨机型,当压榨压力提高幅度为3 MPa时,浮选精煤和煤泥水分降幅均在4个百分点左右;在压榨压力为4 MPa时,增加风穿流,高硫浮选精煤和高硫煤泥的水分降幅分别为5.15和2.67个百分点。采用风穿流机型,当压榨压力由0.8 MPa提高至1.2 MPa时,高硫、低硫的浮选精煤水分降幅分别为6.4和2.2个百分点;当压榨压力由1.2 MPa提高至1.6 MPa时,高硫、低硫的浮选精煤水分降幅分别为0.1和0.3个百分点;说明对于风穿流机型,压榨压力为1.2 MPa时,浮选精煤压滤脱水效果最佳。随着风穿流时间的增长,2种机型作用下的浮选精煤和煤泥的水分均呈下降趋势,且降幅逐渐收窄,浮选精煤水分降幅大于煤泥水分降幅。通过数据对比,结合物料附加值,浮选精煤优先选用风穿流机型,煤泥优先选用高压压榨机型,该选型原则在工业应用得到进一步验证。最后,根据工业应用经验,给出风穿流机型的配套风包选型为8~10 m^(3)/100 m^(2)(过滤面积)。

某铅锌矿选矿试验研究

对某铅锌矿进行选矿工艺流程试验研究,该矿石铅锌品位较高,闪锌矿分布不均匀,以中细粒为主,铅锌矿物嵌布关系密切,铅锌分离难度较大;通过铅粗选磨矿细度、铅粗精矿再磨细度、铅粗选石灰、铅粗选HB26、铅粗选HB535、铅粗选HB165、铅精选I石灰、铅精选I HB26、铅精选I HB535、锌粗选2#油、锌精选I石灰、锌精选I丁基黄药用量试验,采用原则流程铅锌顺序优先浮选,获得了铅精矿铅品位64.80%、含锌7.07%、铅回收率93.67%,锌精矿锌品位50.11%、含铅0.98%、锌回收率88.47%,硫精矿品位50.02%、硫回收率35.23%的试验指标。

某20万吨再生铅项目设计及能耗分析

本文以某年产20万吨再生铅项目为例,首先对项目的工艺流程进行了简要介绍,其次对项目主要工艺流程包括富氧双侧吹熔池熔炼系统、粗铅火法精炼系统和冶炼烟气脱硫制酸系统进行详细介绍。通过对主要工艺耗能分析,提出有针对性的工艺节能措施,以期达到良好的节能效果。

空气穿流模式在洗煤厂压滤机自动化改造中的应用

针对浮选工艺中压滤机升级改造技术的应用展开研究,按空气穿流压滤的工作原理,对压滤机滤板、压紧板、止推板进行打孔和堵孔改造,利用高压风瞬间吹风,强力吹透滤饼,在压滤机内形成新的脱水风道。同时,升级现有压滤机的自动控制程序,可实现自动控制运行,达到滤饼穿流脱水的目的。

Application of shear-sensitive liquid crystal coating to visualization of transition and reattachment in compressor cascade

The present paper aims at introducing Shear-Sensitive Liquid Crystal Coating(SSLCC)technology into compressor cascade measurement for the first time and serves as a basis for better understanding of the influence from the boundary layers. Optical path layout, which is the most significant difficulty in internal flow field measurement, will be solved in this paper by selfdesigned image acquisition device. Massive experiments with different Mach number and incidence are conducted at a continuous subsonic cascade wind tunnel to capture the boundary layer phenomenon. Image processing methods, such as Three-Dimensional(3-D) reconstruction and Hue conversion, are used to improve the accuracy for transition position detection. The analysis of the color-images indicates that complex flow phenomena including transition, flow separation,and reattachment are captured successfully, and the effect of Mach number and incidence on the boundary layer flow is also discussed. The results show that: the Mach number has a significant effect on transition position; the incidence has little effect on transition position, but it has a great impact on the transition distance and leading-edge separation; influenced by the end-walls, the reattachment occurs in advance under positive angle of attack conditions.