Cross-linked polyvinyl amidoxime fiber: a highly selective and recyclable adsorbent of gallium from Bayer liquor

Gallium, a scarce metal produced mainly from Bayer liquor, is widely used in semiconductors. Ion-exchange method is currently considered as the most effective method to recover gallium from Bayer liquor. In this article, fibrous amidoxime adsorbents are introduced to recover gallium from Bayer liquor. In addition, hydrazine cross-linked polyvinyl amidoxime (HPAO) fibers have been prepared. The structure of the as-prepared fibers was ascertained by FTIR, elemental analysis and weight gain rate. The adsorption kinetics, adsorption isotherm and recycling performance were investigated by batch method. Cross-linking duration was studied and it turned out to be an important factor to optimize the adsorption capacity and recycling performance. After 1.5 h cross-linking time, the fiber showed the highest gallium adsorption capacity of 14.83 mg/g in Bayer liquor. After 3 h cross-linking time, the fiber showed the best recycling performance, which retained 82.9% of the initial adsorption ability after four cycles. Adsorption capacity of vanadium was lower than 1 mg/g for all samples. HPAO displayed very fast adsorption kinetics with an equilibrium at 60 min. The EDS results confirmed the low extraction of aluminum and vanadium provided by HPAO fibers. The gallium-loaded fiber could be effectively eluted by acidified thiourea. With proper control of the cross-linking duration by hydrazine, HPAO fiber with high selectivity towards gallium, high adsorption capacity and good recycle performance could be obtained, which is promising for recovering gallium needed for industrial applications.     

南海中尺度海域低放废水数值模拟研究

低放废水的排放一直是国内外关注的问题,目前国内多数研究采用小尺度海域模拟短期低放废水排放后的迁移扩散状况。以南海中尺度海域为例,采用MIKE模拟软件,分析南海中尺度海域的潮汐特征,模拟计算低放废水长期排放后的浓度场分布规律。研究表明:放射性核素氚的浓度场分布情况主要受到潮流场、余流的影响,雷州半岛东部低放废水排放情形下,放射性核素环抱于雷州半岛,并在北部湾迁移扩散,主要流向为西北和西南向;雷州半岛西部排放的主要流向为西北和西南向。就东西部低放废水排放比较而言,西部排放更加有利于低放废水的稀释扩散,排放口附近海域氚的浓度活度较高,对海洋环境敏感目标影响较小。     

Hydroxyapatite coating by dipping method,and bone bonding strength

Hydroxyapatite (HA) was coated onto titanium rods by a dip coating method using HA sol. The HA sols were prepared by dispersing HA crystals less than 100 nm length in distilled water or physiological salt solution using an ultrasonic homogenizer. The surface of the HA coating was homogeneous as determined by scanning electron microscopy (SEM). After implantation of uncoated and HA dip coated titanium rods in dog femurs, new bone formation was observed only around the coated material. The bone bonding strength to HA coated rods was 1.0, 1.5, 2.0 and 2.5 Mpa after 1,2,3 and 4 weeks implantation, respectively, as determined by pull-out testing. These values were over twice that of the uncoated titanium rods at 1–4 weeks after implantation. The dip coated titanium exhibited superior biocompatibility to the uncoated implant and may be of great value for bone repacement applications.This paper was accepted for publication after the 1995 Conference of the European Society of Biomaterials, Oporto, Portugal, 10–13 September.     

钼酸铅晶体表面红外增透膜的研究

本文讨论了用于钼酸铅晶体表面的宽带红外增透膜的设计以及其在真空环境中的制备。膜系设计中 ,运用反射率图解法以获得满意的光学性能 ;与传统的热蒸发镀膜工艺相比 ,在真空沉积过程中采用了离子辅助沉积技术 ,从而大大提高了膜层的光学特性及膜层品质。试验表明所镀膜层性能优异 ,在光纤通信领域具有广阔的应用前景     

中尺度海域核设施低放废液排放方案的初步探究

以某海域为例,初步探究某核设施正常运行时低放废液在中尺度海域的排放方案。采用MIKE21模拟软件,利用水动力模块(HD)和对流扩散模块(AD)建立了中尺度海域放射性核素迁移扩散数值模型,以半衰期为12.5年的放射性核素氚为例,考虑了排放口离岸距离、排放口方位和不利风向等因素,对放射性核素在中尺度海域的迁移分布状况进行了数值模拟。初步计算结果表明,排放口设在某河口东北侧,距岸不小于30 km的海域,有利于放射性核素的迁移、扩散。     

弹丸初速可调的电磁轨道炮对空射击策略

基于电磁轨道炮射弹速度可调的特点,研究其对视距内空中目标的射击策略。建立弹丸六自由度外弹道运动方程组以及弹丸对空中目标单发射击、全航路连续射击时的命中概率模型,系统分析单发射击、全航路连续射击下目标距离、弹丸初速对命中概率的影响。结果表明：单发射击下弹丸初速越大,目标命中概率越大;全航路连续射击下,累积命中概率随着弹丸初速增大,整体趋势上先增大、后减小,但存在局部阶跃下降现象;由近及远、有效射程内单发命中概率最大、射击远界上多发同时弹着的全航路平衡射击策略可兼顾全航路累积命中概率和舰炮打击成本,以较小的打击成本获得较优的作战效能。     

基于随机共振的轴承早期微弱故障诊断

针对早期轴承微弱信号难以发现、检测精度低等问题,提出一种基于随机共振的轴承早期微弱故障诊断方法。首先利用排列熵对周期信号的敏感特性,提出一种新的信号筛选方法来对信号进行初步滤波筛选;其次采用随机共振算法对故障信号进行噪声辅助增强,以信噪比为目标函数,采用麻雀搜索算法对随机共振系统参数k、a、b、h进行寻优,最后将寻优后的参数送入随机共振系统进行检测。仿真结果表明：该方法可以有效检测出强噪声中的未知微弱故障信号。     

临港工业区建设对核电厂液态流出物稀释扩散的影响

临港工业区建设会导致核电厂取排水口局部潮流场发生变化,影响液态流出物稀释与扩散。以中国北部湾的廉江港为例,采用二维数值模拟计算核电厂2台机组投入运行后,考虑和不考虑临港工业区两种情况下夏季中潮¹³¹I和⁶⁰Co在取排水口附近海域的浓度分布和时空变化。结果表明:临港工业区建设前,¹³¹I和⁶⁰Co主要随潮流运动,¹³¹I和⁶⁰Co稀释10倍的浓度平均值包络面积分别为0.9×10^-3km²和1.2×10^-3km²,高浓度区主要分布于排水口所在的安铺湾。临港工业区建设后,潮流场仅在工业区附近发生变化,变化幅度工业区东侧明显大于西侧,并在东侧形成回流区,挑流作用使附近水域的流动减弱,贴近工业区受影响最大,流速、流向均有较明显的改变。¹³¹I和⁶⁰Co稀释10倍的浓度平均值包络面积分别为1.0×10^-3km     

Click‐Chemistry‐Mediated Rapid Microbubble Capture for Acute Thrombus Ultrasound Molecular Imaging

Bioorthogonal coupling chemistry has been studied as a potentially advantageous approach for molecular imaging because it offers rapid, efficient, and strong binding, which might also benefit stability, production, and chemical conjugation. The inverse‐electron‐demand Diels–Alder reaction between a 1,2,4,5‐tetrazine and trans‐cyclooctene (TCO) is an example of a highly selective and rapid bioorthogonal coupling reaction that has been used successfully to prepare targeted molecular imaging probes. Here we report a fast, reliable, and highly sensitive approach, based on a two‐step pretargeting bioorthogonal approach, to achieving activated‐platelet‐specific CD62p‐targeted thrombus ultrasound molecular imaging. Tetrazine‐modified microbubbles (tetra‐MBs) could be uniquely and rapidly captured by subsequent click chemistry of thrombus tagged with a trans‐cyclooctene‐pretreated CD62p antibody. Moreover, such tetra‐MBs showed great long‐term stability under physiological conditions, thus offering the ability to monitor thrombus changes in real time. We demonstrated for the first time that a bioorthogonal targeting molecular ultrasound imaging strategy based on tetra‐MBs could be a simple but powerful tool for rapid diagnosis of acute thrombosis.