Sol-gel Preparation and Preliminary in vitro Evaluation of Fluorapatite／Hydroxyapatite Solid Solution Films

Fluorapatite/hydroxyapatite solid solution has better biological properties than other apatites, especially used as films or coatings. In this work, sol-gel preparation and in vitro behavior of fluorapatite/hydroxyapatite solid solution films on titanium alloy were investigated. Ca(NO3)2-4H20 and PO(OH)x(OEt)3-x were selected as precursors, and hexafluorophosphoric acid (HPFo) was used as a fluorine containing reagent. The Ca and P precursors were mixed with HPFo to keep the Ca/P molar ratio 1.67. The mixtures refluxed for 12 h were used as dipping sols for the preparation of the films. The phase of the films obtained at 600℃ was apatite. The F contents in the films increased with the concentrations of HPF6 in the dipping sols. The solid solution films were shown to have better stability than hydroxyapatite films, and a reasonably good bioactivity in the in vitro evaluation.     

锌(Ⅱ)-氨基酸配合物分子内配体间疏水作用

应用 p H电位滴定法研究了配合物 Zn( Aa) 2 [Aa-=L- val(缬氨酸根 ) ,L- phe(苯丙氨酸根 ) ,L- trp(色氨酸根 ) ,L- tyr(酪氨酸根 ) ]在水和 2 0 %、40 %及 60 %二氧六环 /水溶液中的稳定性 [t=2 5℃ ,c=0 .1 mol/L Na Cl O4]。配合物 Zn( Aa) 2 相对于母体配合物 Zn( Aa) + 稳定性用Δlog K=log KZn( Aa)Zn( Aa) 2 - log KZn Zn( Aa) 表示。结果表明 :与 L-丙氨酸 ( L- ala)配合物 Zn( L- ala) 2 相比 ,所有这些氨基酸配合物 Zn( Aa) 2 均具有相对较大的 Δlog K值 ,表明这些配合物分子内存在着额外的稳定化作用。这种稳定性化作用可能主要归因于配合物分子内氨基酸侧链之间的疏水作用 ,并且这种作用随着氨基酸侧链结构及溶剂极性变化而变化     

Research and application of automatic control system of argon blowing at ladle shroud

Argon blowing at the ladle shroud requires the best flow control strategy to effectively avoid the secondary oxidation of molten steel, slag entrapment and heat loss during the casting of the tundish, and at the same time, give full play to the role of bubbles to remove inclusions. Therefore, an automatic control system for argon blowing at the ladle shroud was proposed. The data collected by S7-300PLC and software programming were used to adjust the argon blowing flow online in real time according to factors such as pouring and continuous pouring. On this basis, PID control algorithm and closed loop control mechanism were used for real time adjustment. The flow control valve ensures theminimum deviation between the actual value of the flow and the set value. The production data of this system in the first quarter of 2021 in a special steel plant show that the proportion of furnaces with an acid soluble aluminum (Als) loss percentage of less than 10% of each steel grade has increased by 5.52%, and the proportion of furnaces with an Als loss percentage of more than 60% has increased from 1% decrease to 0. The actual application results show that the use of the system improves the surface quality of the continuous casting slab and the performance of the final product.     

蜗杆副的跑合工艺

叙述了蜗杆副跑合的目的、作用以及跑合过程的特点和跑合中应重视的几个问题。     

建设工程质量保证体系存在的问题及对策

结合建筑业市场管理体制的改革及其发展态势，就建筑工程质量保证体系存在的问题作了阐述，从加强勘察设计资格的管理，完善监理法规等方面，提出了健全和完善质保体系的措施。     

螺纹钢牙筋长度不足的原因及解决办法

分析了影响螺纹钢牙筋长度的原因，根据铣床的工作原理，利用刀头夹持长度与凸轮工作轨面半径的几何关系，推导出计算各种不同规格螺纹钢牙筋的工艺参数，解决了螺纹钢牙筋长度不足之问题。     

P／MCs新型复合材料制备、结构及阻尼性能

采用特殊的渗流法所制备的新型Ｐ／ＭＣｓ复合材料，由高分子聚合物与蜂窝状铝架组成，它具有优异的阻尼性能，并简述了结构对阻尼的影响     

适合航天电子系统应用的DC－DC变换器

讨论了航天ＤＣ－ＤＣ混合集成电路的拓朴结构。通过对几种电路的性能比较，提出了适合航天应用的ＤＣ－ＤＣ变换器的最佳拓朴结构。论述了ＰＷＭ－ＬＩＮ变换器的控制方法，该方法对于确保二次稳压ＤＣ－ＤＣ变换器较高的效率具有重要意义，亦可大大提高混合集成电路的成品率。     

树脂悬浮光度法测定微量银

在ｐＨ６．９的缓冲溶液中，银与硫代米Ｃｈｉ酮（ＴＭＫ）形成的螯合物在树脂甘油相中悬浮富集，用光度法测定银在波长４６１ｎｍ处有最大吸收，银在０～６μｇ／１０ｍＬ范围内遵守比尔定律，可用于样品中微量银的测定。     

半导体陶瓷致冷材料的性能与结构

采用新的陶瓷工艺技术,在气氛保护条件下,通过固相烧结反应法制备出温差电多晶材料。对膺三元固溶体化合物 P 型(72%Sb_2Te_3+25%Bi_2Te_3+3%Sb_2Se_3)和 N 型(90%Bi_2Te_3+5%Sb_2Te_3+5%Sb_2Se_3)的掺杂陶瓷样品进行了性能与结构研究。找到了最佳工艺制度。样品性能参数为:N 型:α=186μV/K σ=1250Ω~(-1)·cm~(-1) λ=14.7mW/(cm.K) Z=2.9×10~(-3)/KP 型:α=220μV/K σ=900 Ω~(-1)·cm~(-1) λ=14.0mW/(cm.K) Z=3.1×10~(-3)/K