Encapsulation of Hydroxyapatite Microspheres with Fluorapatite Using a Diffusion Process

Modification of hydroxyapatite surfaces can improve the properties of biomedical devices. The objective of this work was to encapsulate hydroxyapatite particles with a fluorapatite layer. A suspension of hydroxyapatite microspheres was prepared in a solution at different pH and treated with ammonium fluoride. pH, calcium, and fluoride were monitored in real time and particles subjected to fluoride analysis. After addition of fluoride, it was found that more material is released from the particle surface at low pH conditions, but leads to a high fluoride uptake from solution. Low solution fluoride levels produce a fluorapatite layer, but higher fluoride levels produce calcium fluoride.     

库水升降速率对老蛇窝滑坡稳定性影响分析

通过监测资料分析和滑坡稳定性数值计算,探讨了三峡库水位在不同升降速率下对老蛇窝滑坡稳定性的影响规律。研究结果表明,理论上库水位上升有利于老蛇窝滑坡的稳定,但实际运行中库水位上升是不利于滑坡稳定的,因为库水浸泡会使滑坡前缘塌岸;老蛇窝滑坡为动水压力型滑坡,最主要诱发因素为库水位的下(骤)降;老蛇窝滑坡稳定性的临界库水位调度速率为0.9 m/d,即当库水位下降速率大于0.9 m/d时,滑坡K值小于1。     

货架喷塑前处理工艺的选择与应用

介绍了CZ99-03(7)常温锌系磷化剂在货架上的应用,根据货架构件的特点,优化货架喷塑前处理工艺,讨论了影响磷化质量的工艺因素,提出了提高磷化效果的措施以及进一步改进磷化工艺的工艺设计。     

关于高氮尿素磷肥工艺的试验研究

介绍一种用尿素生产高氮磷肥的新工艺 ,分析该工艺的技术参数和影响因素。新工艺克服了过磷酸钙和尿素直接相混时会释放出结晶水的局限性 ,所得产品不仅可以作为复肥生产的原料 ,而且可以直接喷浆造粒生产NP复肥 ,因而具有良好的实用性     

Partial acidulation of an ‘unground’ phosphate rock: II. Plant availability of phosphate

Four greenhouse experiments were conducted using three soils to determine the availability to plants of P from unground North Carolina phosphate rock (PR) treated with 20% to 50% of the H₃PO₄ required for complete acidulation. The influences of soil P retention, P status, the method of preparation of partially acidulated phosphate rocks (PAPRs) and the granule size of the products were investigated. Perennial ryegrass was grown as the test plant for up to 8 months. Triple superphosphate (TSP) was used as the standard fertilizer and unground North Carolina rock was included for comparison.The dry matter yield and P uptake response curves showed that in all experiments PAPRs were markedly superior to the PR. P status of soils appeared to influence the effectiveness of PAPRs to a greater extent than P retention. In soils of low P status the degree of acidulation required for PAPR to be nearly or as effective as TSP was 50% whereas in a soil of high P status even 30% PAPR applied as a maintenance fertilizer was effective. There was a significant positive correlation between water soluble P of fertilizers and P uptake by ryegrass. However, in general PAPRs were more effective per unit of water soluble P than TSP. Granule size (< 1 mm and 1–2 mm) and method of preparation of PAPRs did not alter the effectiveness of PAPRs.     

葡萄糖-6-磷酸和果糖-6-磷酸的酶法测定

在血液、发酵液或组织液中加入磷酸葡萄糖异构酶（ＰＧＩ，ＥＣ．５．３．１．９）、６－磷酸葡萄糖脱氢酶（ＧＤＨ，ＥＣ．１．１．１．４．９）及还原型辅酶Ⅱ（β－ＮＡＤＰ），利用快速、准确的酶法检测Ｄ－６－磷酸葡萄糖和Ｄ－６－磷酸果糖浓度。对该法的专一性、精确性、准确性以及误差来源及消除方法作了讨论。对其它物质的分析作了探讨     

贵州省磷化工现状及发展前景

阐述贵州磷资源、煤炭、电力基本情况及在全国的地位和我省发展磷化工的重要意义。介绍我省磷化工生产现状、生产能力、实际产量、产品出口等情况。对世界磷化工产品市场需求，我国和我省的磷化工到2000年的发展情况，达到的目标进行初步援测和构想，并对我省磷化工发展对策进行探讨，提出几点建设性意见。     

Exploration of mesoporous structure of tunisian raw and acid-leached phosphate ore particles

Rock phosphate fractions were examined for their porous structure by nitrogen adsorption. The pore size distribution and the shape of pores does not seem to depend on the particle size. The specific surface area values present two regions, one above and one below that of the particles with 125 μrn diameter. Particles of a given size were leached with dilute phosphoric acid (1.5 mass% P₂O₅) at 25°C. It was observed that there is a widening of the initial pores during leaching. The particles collected at the initial period of the reaction are pitted and those collected at the final period are disintegrated.     

磷矿中氧化钙,氧化镁测定方法的研究

用硝酸铋分离磷酸根离子，在滤液中用ＥＧＴＡ－ＥＤＴＡ分别测定氧化钙，氧化镁较之传统方法简便效果好。     

Oxidation of Butane to Maleic Anhydride using Vanadium Phosphate Catalysts: Comparison of Operation in Aerobic and Anaerobic Conditions using a Gas-gas Periodic Flow Reactor

The use of a periodic flow reactor is described for the oxidation of butane to maleic anhydride to compare the catalytic performance of vanadium phosphate catalysts operating under aerobic and anaerobic conditions. It is found that for the catalyst prepared via a standard VPO method, operation in the absence of oxygen leads to a very small enhancement in selectivity when butane concentrations in the range 0.9–2.9% are used. Operation in the absence of oxygen leads to very small differences in conversion such that the overall yield is enhanced and this effect is maximised for reactor feeds containing 1.5% butane. However, the enhancement is negligible when the catalyst is operated at high conversion required for commercial operation, indicating that reactors operating with continuous flow with aerobic conditions are preferred. Similar experiments are conducted for a catalyst prepared by the VPD method and, in contrast, this catalyst gives lower butane conversion and maleic anhydride selectivity when operated in the absence of oxygen.