The power reflected in a SAW RAC

Considerations relating to the design of surface-acoustic-wave (SAW) reflective array pulse compressors (RACS), including the effect of array width on power reflected, the transmitted beam profile and the effect of randomized arrays, are discussed. Only a first-order analysis is used. Potential misunderstandings of these issues that could arise from the existing literature are clarified.     

经食道心房调搏的放射性核素心血管造影

本文应用反符合电路剔除调搏脉冲干扰的方法,制成经食道心房调搏心电心音门电路触发装置,用于经食道心房调搏的核素心血管造影。参考Tzivoni标准,当逐级增加调搏心率至140次/min或亚极量心率后发现:冠心病人有调搏后EF降低;急性心肌梗塞病人EF减低更为明显,并呈室壁反向运动。因此,心房调搏核素心血管造影有助于冠心病,特别是心肌梗塞的诊断。     

Red-Blood-Cell-Membrane-Coated Metal-Drug Nanoparticles for Enhanced Chemotherapy

To overcome high toxicity, low bioavailability and poor water solubility of chemotherapeutics, a variety of drug carriers have been designed. However, most carriers are severely limited by low drug loading capacity and adverse side effects. Here, a new type of metal-drug nanoparticles (MDNs) was designed and synthesized. The MDNs self-assembled with Fe(III) ions and drug molecules through coordination, resulting in nanoparticles with high drug loading. To assist systemic delivery and prolong circulation time, the obtained MDNs were camouflaged with red blood cell (RBCs) membranes (RBCs@Fe-DOX MDNs) to improve their stability and dispersity. The RBCs@Fe-DOX MDNs presented pH-responsive release functionalities, resulting in drug release accelerated in acidic tumor microenvironments. The outstanding in vitro and in vivo antitumor therapeutic outcome was realized by RBCs@Fe-DOX MDNs. This study provides an innovative design guideline for chemotherapy and demonstrates the great capacity of nanomaterials in anticancer treatments.     

CHARAC TERIZATION OF TiAl POWDER PRODUCED BY MECHANICAL ALLOYING

The microstructure,alloying reaction and sintering behavior of the powder produced by Mechanical Al-loying(MA)for 8 h from 64 wt.-% Ti powder and 36 wt.-% Al powder were studied by scanning electronmicroscopy,optical microscopy,X-ray diffractometry,differential scanning calorimetry(DSC)and dilatometry.The mechanically alloyed powder partictes are Ti-Al composite particles.Thus,titanium aluminides can formeasily in the powder through diffusion during heat treatment.It is shown that the sintering behavior of this pow-der,different from the behaviors of TiAl alloy powder and mixed powder of 64 wt.-% Ti powder and 36 wt.-%Al powder,changes from expansion at temperatures below 1000℃ to shrinkage at temperatures above 1000℃.Homogeneously alloyed TiAl material with a density over 96% of the theoretical density can be produced fromthe mechanically alloyed powder by compaction-sintering.     

Mold-filling characteristics of AZ91 magnesium alloy in the low-pressure expendable pattern casting process

The magnesium (Mg) alloy low-pressure expendable pattern casting (EPC) process is a newly developed casting technique combining the advantages of both EPC and low-pressure casting. In this article, metal filling and the effect of the flow quantity of inert gas on the filling rate in the low-pressure EPC process are investigated. The results showed that the molten Mg alloy filled the mold cavity with a convex front laminar flow and the metal-filling rate increased significantly with increasing flow quantity when flow quantity was below a critical value. However, once the flow quantity exceeded a critical value, the filling rate increased slightly. The influence of the flow quantity of inert gas on melt-filling rate reveals that the mold fill is controlled by flow quantity for a lower filling rate, and, subsequently, controlled by the evaporation of polystyrene and the evaporation products for higher metal velocity. Meanwhile, the experimental results showed that the melt-filling rate significantly affected the flow profile, and the filling procedure for the Mg alloy in the low-pressure EPC process. A slower melt-filling rate could lead to misrun defects, whereas a higher filling rate results in folds, blisters, and porosity. The optimized filling rate with Mg alloy casting is 140 to 170 mm/s in low-pressure EPC.     

电感电容损耗电阻的讨论

通过对电容电感阻抗的测量，发现实验值偏离理论值。定性地分析了误差的来源，得出的结论是电感电容内部的损耗电阻随着频率的变化而变化，变化方向相反而并非相同。     

活性酯硬化水玻璃砂的研究

用焙烧活性砂混制而成的活性酯硬化水玻璃砂与普通酯硬化水玻璃砂相比，强度成倍提高，从而减少水玻璃的加入量，改善水玻璃砂的溃散性。实验证明：原砂的表面活性直接影响在水玻璃砂中水玻璃的加入量，是改善水玻璃砂溃散性的关键之一。焙烧活性砂的水玻璃加入量只要１．５％～２．０％，即能满足实际生产的强度要求。     

氰化氢在终冷塔中气液两相之间转移的研究

分析了煤气中氰化氢的形成,论述了氰化氢在煤气和其冷凝液中的平衡机理,讨论了影响氰化氢相平衡的因素,研究了直接终冷、间接终冷时煤气中氰化氢的转移情况。     

气流床水煤浆气化技术的应用现状及开发进展

气流床水煤浆气化是煤高效、洁净利用的一项关键技术。简述了具有代表性的气流床水煤浆气化技术的应用现状及开发进展,并分析了影响水煤浆气化的主要因素,如烧嘴、耐火砖、进料系统、激冷环等,提出了一些改进措施。     

提高磷酸二铵产品质量方法浅析

针对磷酸二铵(DAP)产品养分波动大、含水量偏高、易结块、颜色变化大等缺点,在生产过程中采取了相应的解决措施,如配矿、联产、设备改造、工艺指标调整等,使DAP装置不仅保持了原有的优点,而且产品质量问题也得到了有效解决。养分基本保持在64.0%~64.6%,水分下降到2.1%~2.2%,结块现象较少,颜色也比较统一。