均匀设计在烷基水杨酸钙合成中的应用

运用均匀设计对烷基水杨酸钙碱化反应进行研究，成功解决了产品钙含量、碱值偏低的主要问题。探讨了促进剂第一次和第二次加量、溶剂量及C02流量等因素的影响，建立了钙含量和碱值的数学模型，通过参数优化，确定了优化工艺条件。实验结果表明，在保证烷基水杨酸投料一定的前提下，促进剂两次进料比约为50：(60—65)g，溶剂用量为135—150g，C02流量控制在150ml/min以下，产品钙含量可达6．85％，碱值可达187mgKOH/g，产品质量明显提高。同时说明采用均匀设计进行实验，不仅可以提高工作效率、提高试验水平、节约时间、节约经费，而且利用它所建立的数学模型及模拟的单因素变化规律符合实际反应情况，并能进行推确、有效的预报，对生产具有积极的指导作用。     

冷镦钢SWRCH22A炼钢工艺优化研究

主要介绍了首钢水钢冷镦钢SWRCH22A炼钢生产工艺优化的改造实践。针对冷镦钢SWRCH22A工艺存在钢水回si现象严重、可浇性不稳定的问题采取相应的优化工艺措施,通过生产工艺的优化,水钢生产的SWRCH22A钢水回si量由开发初期的平均0．04％降至平均0．02％,连浇炉数由2炉提高至7炉。生产节奏和品质明显提升。     

Continuous microwave assisted flow synthesis and characterization of calcium deficient hydroxyapatite nanorods

Synthetic calcium deficient hydroxyapatite (CDHA) nanorods (<100?nm) were rapidly prepared with the help of a new continuous microwave assisted flow synthesis (CMFS) reactor in 5?min only from aqueous solution of calcium hydroxide and orthophosphoric acid at pH 8.5. The effect of various reaction parameters like, pH, concentration, temperature, residence time, degree of crystallinity and particle surface area were studied in detail. The phase purity, particle size and morphology of the powder samples were characterised by techniques such as X-ray diffraction analysis, transmission electron microscopy, scanning electron microscopy and FTIR and Raman spectroscopy. With the help of X-ray photoelectron spectroscopy, the chemical analysis was completed. Measurements were taken into account to estimate the particle size following the dynamic light scattering. The results showed that the employed synthesis procedure offered an efficient and economical route to achieve high quality nano-sized products with suitable size and low level of impurities.     

Simulation of methylene blue adsorption by salts-treated beech sawdust in batch and fixed-bed systems

Batch and column kinetics of methylene blue adsorption on calcium chloride, zinc chloride, magnesium chloride and sodium chloride treated beech sawdust were simulated, using untreated beech sawdust as control, in order to explore its potential use as a low-cost adsorbent for wastewater dye removal. The adsorption capacity, estimated according to Freundlich's model, the Langmuir constant K(L) and the adsorption capacity coefficient values, determined using the Bohart and Adams' bed depth service model indicate that salts treatment enhanced the adsorption properties of the original material. Since sawdust is an industrial waste/byproduct and the salts used can be recovered as spent liquids from various chemical operations, this process of adsorbent upgrading/modification might be considered to take place within an 'Industrial Ecology' framework.     

Growth of calcium carbonate by the atomic layer chemical vapour deposition technique

Thin films of CaCO₃ (calcite) have been grown with the atomic layer chemical vapour deposition (ALCVD) technique, using Ca(thd)₂ (Hthd=2,2,6,6-tetramethylheptan-3,5-dione), CO₂, and ozone as precursors. Pulse parameters for the ALCVD-type growth are found and self-limiting reaction conditions are established between 200 and 400 °C. Calcium carbonate films have been deposited on soda-lime glass, Si(100), -Al₂O₃(001), -Al₂O₃(012), -SiO₂(001), and MgO(100) substrates. The observed textures were: in-plane oriented films with [100](001)CaCO₃ [100](001)Al₂O₃ and [100](001)CaCO₃[110](001)Al₂O₃ on -Al₂O₃(001), amorphous films on -Al₂O₃(012) when grown at 250 °C, and columnar oriented films on soda-lime glass, Si(001), -SiO₂(001), and MgO(100) substrates with (00l) and (104) parallel to the substrate plane at 250 and 350 °C, respectively. The film topography was studied by atomic force microscopy and AC impedance characteristics were measured on as-deposited films at room temperature. The films were found to be insulating with a dielectric constant (_r) typically approximately 8. Thin films of CaO were obtained by heat treatment of the carbonate films at 670 °C in a CO₂-free atmosphere, but the thermal decomposition led to a significant increase in surface roughness.     

钙[Ca(NO3)2和CaO]对茶树氟吸收的影响

通过水培和土壤盆栽试验,研究了Ca对茶树F吸收的影响。结果显示,在含F溶液中添加Ca显著降低茶树对F的吸收。在土壤盆栽试验中也得到了类似结果,在2种土壤F含量条件下,加入Ca(NO3)2后显著降低茶树成熟叶和新梢F含量。同样土壤加入CaO后,显著降低茶树对F的吸收。土壤分析表明加入Ca(NO3)2后并没有显著改变土壤水溶性F含量,而加入CaO后还增加了土壤水溶性F含量。因此,Ca减少F吸收可能并不单纯是因为形成CaF2后降低土壤F的有效性。     

微/纳米结构含锌硅酸钙基涂层成骨性能研究

骨科植入物涂层的表面形貌和化学组成对炎症反应的进程和骨形成的发生都发挥着重要调节作用。为综合利用微/纳米仿生结构和生物活性元素的优势,将含锌(Zn)的纳米结构物质引入到经水热处理后的等离子喷涂硅酸钙(calcium silicate, CS)涂层表面,对所制备涂层的物相组成、表面和截面形貌、比表面积、Zeta电位和生理环境下离子溶出等物理化学性能进行了表征。相比于常规CS涂层,具有微/纳米复合结构的CS和含锌CS涂层拥有更高比表面积和孔容,可吸附更多血清蛋白和纤维连接蛋白,通过刺激细胞内整合素以及下游vinculin和FAK基因表达,提高了骨髓间充质干细胞(BMSCs)铺展能力。涂层中锌的引入进一步提高了其表面BMSCs的增殖能力和与成骨细胞分化相关的基因表达。具有微/纳米复合结构的涂层明显上调了RAW264.7巨噬细胞中M2表型因子(CD206和ARG)基因表达,而涂层中溶出的Zn²⁺显著提高了RAW264.7细胞中抑炎症因子(IL-1ra和IL-10)基因表达,促使其向抑炎症表型转化。骨科植入物涂层表面锌元素和纳米结构的引入有利于创建良好的骨免疫微环境,促进骨...     

Novel sol-gel derived calcium phosphate coatings on Mg4Y alloy

Calcium phosphates (CaPs) and silicon containing calcium phosphates (Si-CaPs) coatings on a biodegradable magnesium yttrium alloy (Mg4Y) were prepared by a sol-gel technique to improve the bioactivity of the alloy surface. The experimental results show that thick porous coatings comprised of nano-sized calcium phosphate particles can be prepared by heating the as dip coated substrates at 450 °C. The in vitro degradation results show that the coatings do not alter the degradation kinetics of the substrates significantly and the release of magnesium and yttrium ions at initial time points was very similar for both the coated and bare substrates. The cyto-compatibility studies using MC3T3-E1 osteoblasts show that the coated substrates were more bioactive than the uncoated substrates as the cells begin to grow and form a matrix on the coated substrates more easily than on the bare metal. These preliminary results collectively show the potential of use of sol-gel derived calcium phosphate coatings on magnesium based degradable scaffolds to improve their surface bioactivity.     

Experimental investigation and numerical modeling of chloride penetration and calcium dissolution in saturated concrete

Chloride penetration and calcium dissolution have been investigated for a saturated concrete after exposure to a 0.5 mol/L NaCl solution for a period of up to 3150 days. Simultaneous ion transport model (SiTraM) that allows the transport of chloride and calcium ions to be simultaneously simulated in a hydrated cement system has been used to verify the experimental results.Self-compacting concrete (SCC) with a water to cement ratio of 0.3 resulted in a limited chloride penetration depth while the calcium dissolution was also reduced within the near surface zone. Increased unit water content for normal concrete resulted in higher chloride penetration depth and larger dissolution front of Ca(OH)₂ regardless of having the same water to cement ratio.It was revealed that the SiTraM can predict the profiles of chloride and calcium for self-compacting concrete. It was also found that the primary factor to control chloride penetration front and the dissolution front of Ca(OH)₂ was the pore structure characteristic of concrete.     

Reaction mechanism and size control of CaB6 micron powder synthesized by the boroncarbide method

Reaction synthesis mechanism of Calcium hexaboride (CaB₆) powder was investigated by using CaCO₃-B₄C-C system. Micron-scale CaCO₃ and B₄C powders were used as main raw materials. The synthesized powder was determined by X-ray diffraction, showing no left reactants if enough CaCO₃ was added to compensate the evaporation of calcium atoms at high temperature. The powder morphology was observed through SEM. The synthesized CaB₆ powder formed hard agglomerates which consisted of cubic CaB₆ crystallites when the reaction completely finished. Reaction process was illustrated indicating it was a solid-state reaction occurred from B₄C surface to the centre. The dry high-energy ball milling was used to investigate the influence of ball-milling time on the shape and size of powder particles. The particle granularity was measured by laser size analysis method. It is obvious that the particles were refined greatly after ball milling for 8 h. However, the CaB₆ powder could not been refined markedly after 16 h. Finally, optimized parameters for size controlling were given in this paper.