Protein separation mechanisms in surfactant precipitation systems

Separation of globular proteins (cytochrome c and ribonuclease A) from buffer using precipitation by sodium bis-(2-ethylhexyl) sulfosuccinate (AOT), and their recovery with a counterionic surfactant, trioctylmethylammonium chloride (TOMAC) was investigated. The molar ratio between AOT and the protein (R) required for complete removal was 17 for cytochrome c, and 22 for ribonuclease A. Finally, three mixtures of the two proteins and lysozyme (studied earlier by us) were used to determine the factors controlling separation: selectivity was a strong function of surface charge distribution, indicating that charge interactions between the surfactant and surface groups of different proteins was driving precipitation.     

Comparison of functional properties and secondary structures of defatted wheat germ proteins separated by reverse micelles and alkaline extraction and isoelectric precipitation

The functional properties and secondary structures of defatted wheat germ protein separated by reverse micelles (DWGRMPI) were investigated and compared with those of defatted wheat germ protein separated by alkaline extraction and isoelectric precipitation (DWGPI). The results showed that DWGRMPI had a higher nitrogen solubility index, fat absorption capacity, foaming capacity, foaming stability and emulsifying stability compared to DWGPI, whilst water holding capacity, surface hydrophobicity and emulsifying activity of DWGRMPI were relatively lower than those of DWGPI. DWGRMPI contained high levels of threonine, histidine, alanine, arginine, glycine, serine, cysteine, proline and especially lysine compared to DWGPI. The denaturation temperature and denaturation enthalpy of DWGPI were both lower than those of DWGRMPI, and DWGPI contained more random coil and less α-helix than DWGRMPI, which suggested that DWGPI has lost its ordered secondary structure. This may possibly due to the conditions the used in protein extraction.     

白酒中晶体状沉淀成因探析与预防

通过对白酒中晶体状沉淀的成因探析,探明了白酒中晶状沉淀的产生是由于加浆水硬度过大,所含的Ca2＋和SO42-形成白色晶体状沉淀CaSO4.2H2O,硬度越大、温度越低,沉淀也越多。通常情况下,采用软水加浆工艺,即可解决此类沉淀的产生,较为经济、简便。     

Regulating the multifactor during wet chemical synthesis to obtain calcium phosphate powders with controllable phase purity for bone repair

Calcium phosphate ceramics are widely used as bone repair materials owing to their excellent biocompatibility, bone conductivity, bone induction, and degradability. Although there are many methods for synthesizing calcium phosphate and controlling its phase composition, it is necessary to explore effective preparation methods by understanding the formation of calcium phosphate and its influencing factors. In this study, calcium phosphate powders with controllable phase compositions were synthesized using a wet chemical precipitation method by adjusting the process parameters (aging time, bipolar solution, initial Ca-P molar ratio, capping agent concentration, and system concentration). Subsequently, a certain biphasic proportion of (biphasic calcium phosphate, BCP) products was prepared, and pure (β-tricalcium phosphate, β-TCP) can be obtained according to the customer's requirements. BCP ceramics with desired phase compositions were obtained by pressing and sintering different calcium-deficient powders. Specifically, β-TCP powder with a purity of 99.83 wt% was obtained when the aging time, bipolar solution, initial Ca-P molar ratio, capping agent concentration, and system concentration were 0 h, 50% ethanol, 1, 0.27 M, and 0.0135 M, respectively. The BCP synthesized in this study shows great application potential in the field of bone tissue repair materials.     

化学沉淀法脱除焦化废水中氨氮的研究

采用化学沉淀法处理高浓度氨氮废水,研究了药剂配比、pH值等因素对氨氮去除率的影响。在适当的条件下,可得到纯净的MAP晶体,氨氮的去除率可达98%。在温度为100℃、加热3h将MAP分解后,分解物重复用于脱除废水中的氨氮,氨氮的去除率可达93%,既可大幅度降低药品成本,又可回收废水中的氨。     

9Cr马氏体耐热钢膨胀-温度曲线上的斜率变化研究

9Cr马氏体耐热钢在发生α→γ相变前的升温过程中其膨胀-温度曲线的斜率发生了偏折,偏折点处的温度为660 ℃左右.采用相同的升温速率将该钢样品升温至600、660和750℃三个温度,保温15 min后水淬,利用金相显微镜和扫描电镜分析各样品中组织的差异.研究结果表明,9Cr钢加热至660 ℃和750℃的样品中析出相的数量较600℃明显增加,因此钢中碳氮化物在偏折点温度处的大量析出是膨胀曲线斜率发生明显改变的原因.     

Fe_(16)N_2 的沉淀效应

含氮马氏体室温时效和低于１７５℃回火时有Ｆｅ１６Ｎ２沉淀。Ｆｅ１６Ｎ２的沉淀效应显著,于１００℃回火时沉淀效应最大,ＨＶ、ｃ／ａ比和α（２２０）半高宽均达到最大值。Ｆｅ１６Ｎ２淀淀具有很高的强化效果,纯铁和２０钢渗氮后于１００℃回火,硬度分别提高５８％和６２％。Ｆｅ１６Ｎ２的沉淀效应具有广泛的应用前景     

Effect of metallurgical evolution during post-weld aging treatment on localised corrosion of resistance spot welding joints of A286 superalloy

The combined effect of resistance spot welding and precipitation hardening on the localised corrosion of A286 superalloy is studied. The specimens tested by double loop electrochemical potentiokinetic reactivation were welded in the solution treated condition, and then subjected to different precipitation hardening treatments. For both base metal and weld nugget, the maximum localised corrosion is reached when η phase is clearly observable. The fact that the localised corrosion resistance of weld nugget is different from that shown by base metal may be explained by the segregation of Ni and Ti towards the interdendritic region of weld nugget (studied by using scanning electron microscope/energy dispersive X-ray analysis).     

Preparation of Aqueous Nanodispersions of Disperse Dye by High-Gravity Technology and Spray Drying

Disperse dyes are poorly water-soluble and difficult to stably disperse in an aqueous medium, which greatly limits their application in dyeing synthetic fibers. Micronization can solve this problem. Herein, a facile way to prepare stable aqueous nanodispersions of disperse dye (C.I. disperse yellow 54) is presented by combining high-gravity antisolvent precipitation in a rotating packed bed (RPB) with spray drying. The as-prepared product had an average particle size of 120 nm, which could be readily redispersed in water. Compared with raw dye, the wettability and dispersibility of disperse dye nanoparticles were remarkably improved. Furthermore, the dyeing properties of the nanodispersions were obviously better than those of the commercial dye, which was micronized by ball milling.