直缝埋弧焊钢管焊缝点状缺陷原因分析及改进

为了解决壁厚23 mm直缝埋弧焊管出现的焊缝点状缺陷问题，通过超声波探伤和宏观金相检测对实际生产过程中出现的焊缝点状缺陷不合格试样进行了分析，对铣边坡口形状、焊接工艺参数、焊接材料、焊接设备及焊件清理等方面给出了相应的优化改进措施。现场应用效果表明:这些措施的实施有效控制了此类直缝埋弧焊管焊缝中的点状缺陷，保证了直缝埋弧焊管焊缝形貌及各项力学性能指标，提高了焊接质量。     

Potential Applications of Cucurbit[n]urils Inclusion Complexes in Photodynamic Therapy

Cucurbit[n]urils (CB[n]s) have emerged as potential candidates for drug delivery in several areas due to their strong binding interactions and low toxicity. More recently, their benefits for a type of cancer treatment termed Photodynamic Therapy (PDT) have been recognized. The outcomes of this therapy rely on better drug delivery strategies and improving overall photoactivity of the drugs, which is where CB[n]s could have a strong impact. The effects of these molecular containers on photoactivity are discussed and new interesting work is highlighted.     

Viscosity reduction of isotonic solutions of the photosensitizer TPCS2a by cyclodextrin complexation

Meso-tetraphenyl chlorin disulphonate (TPCS_2a) is a photosensitizer (PS) particularly developed and patented for use in the technology of photochemical internalization (PCI) against cancer. TPCS_2a is known to aggregate in aqueous media even at low concentrations (≥0.1?µM) and to form a high-viscosity network at clinically relevant concentrations (mM). The aim of this work was to evaluate the effect of two hydroxypropylated cyclodextrin derivatives of beta and gamma type, respectively i.e. HPβCD and HPγCD, on the aggregation and solubilization of TPCS_2a in isotonic solutions. Samples containing micromolar concentrations of TPCS_2a were studied spectrophotometrically, while samples containing a clinical relevant concentration (10?mM?=?9?mg/ml) of TPCS_2a were evaluated by dynamic viscosity measurements. HPβCD was determined to be a more suitable solubilizer of TPCS_2a than HPγCD in aqueous media both in the absence and presence of salt. The complexation stoichiometry between TPCS_2a/HPβCD at micromolar to millimolar concentrations of TPCS_2a was determined to be 1:3 and 1:2 in the absence and presence of isotonic NaCl, respectively. The network of TPCS_2a (10?mM) was broken down in the presence of 3% w/v (=?20?mM) HPβCD, i.e. a 1:2 molar ratio between TPCS_2a and the cyclodextrin. Formation of the inclusion complex resulted in low viscosity samples both in water and in the presence of isotonic NaCl or phosphate buffered saline (PBS) at 25?°C and 37?°C.     

耐蚀合金中TiN析出机制

摘要：TiN颗粒尺寸及其分布对耐蚀合金性能有明显的影响，因此有必要对TiN在铸坯中的分布及其析出行为进行研究。采用扫描电镜(SEM)、金相显微镜（OM）观察了TiN夹杂物在铸坯中的分布、尺寸及其形貌；基于热力学和动力学理论分析了耐蚀合金铸坯中TiN夹杂物的析出时机及其尺寸，结合试验结果和理论计算明确了TiN夹杂物在凝固后铸坯中的位置和尺寸与析出时机的关系，为控制TiN夹杂物提供理论指导。结果表明，冶炼过程中析出的TiN夹杂物尺寸较大，在凝固过程中被枝晶吞没，位于铸坯枝晶内和等轴晶内；微观偏析计算结果表明，在凝固分数为0.55时，TiN开始析出，最开始析出TiN夹杂物的逐渐长大，长大后的TiN易于被二次枝晶吞没，最终位于铸坯中的枝晶间和等轴晶内，后期析出的TiN则在枝晶间和等轴晶间。固相中析出的TiN夹杂物长大较慢，尺寸细小，最终位于奥氏体晶界。     

诱发IAF夹杂物与原晶粒的尺寸匹配关系

 对于氧化物冶金船板钢而言，细小弥散分布的夹杂物会对其原始晶粒产生钉扎和诱发晶内铁素体的双重作用，且研究发现诱发晶内铁素体的夹杂物尺寸与原始奥氏体晶粒尺寸存在一定的匹配关系。围绕上述问题进行了系统的分析研究和数据统计,结果表明，不同晶粒尺寸下，诱发晶内铁素体的夹杂物尺寸与原奥氏体晶粒度间存在近似线性关系，且随着奥氏体晶粒度的增大，诱发晶内铁素体的夹杂物尺寸则相应减小。     

电渣重熔过程结晶器旋转对钢中夹杂物的影响

基于自行设计的双极串联结晶器旋转电渣重熔炉，采用ASPEX全自动夹杂物分析仪研究了结晶器转速对M2电渣锭洁净度的影响。结果表明，不论结晶器是否旋转，电渣锭中的夹杂物组成基本不变，主要由Al2O3, Al2O3–MnS, Al2O3–SiO2–CaO–MnS, MgO–Al2O3–SiO2–CaO–MnO, MgO–Al2O3–SiO2–CaO–TiO2–MnS, Al2O3–SiO2–CaO–MnO–TiO2组成，其中以Al2O3, Al2O3–SiO2–CaO–MnO–TiO2和Al2O3–MnS数量最多。结晶器静止电渣重熔时，钢中的夹杂物数量较多，且存在50 ?m以上的大颗粒夹杂物，而结晶器转速为6和13 r/min时，夹杂物数量减少，大颗粒夹杂含量大大降低；转速增至19 r/min时，夹杂物数量及尺寸又进一步增加，同时钢中全氧含量、氮含量明显增加。电渣锭中大颗粒夹杂物得以去除的主要原因是结晶器旋转导致金属自耗电极末端的熔融层变薄、熔滴尺寸变小，渣–金接触面积增大，促进了夹杂物被熔渣去除；过快的转速会增加自耗电极氧化、减少渣–金接触时间，从而降低电渣重熔过程的精炼能力。     

异型中间包结构优化对帘线钢夹杂物的影响

为了解决帘线钢中因大颗粒夹杂物导致的拉拔断裂问题，通过水模型研究结果对异型中间包结构改进优化，并将优化异型中间包结构进行工业试验。结果表明，挡墙优化结构后,去除夹杂物的效果明显提高，采用优化的挡墙中间包生产的帘线钢铸坯中夹杂物尺寸不大于10 μm比例为87.95%，平均尺寸为6.7 μm；大颗粒的高MgO类和高SiO2类夹杂物已得到有效去除，盘条中B细不大于0.5级比例达到97.56%。     

尿素包合法富集压榨松籽油中皮诺敛酸工艺优化

以压榨松籽油为原料,研究乙醇浓度、脂肪酸与尿素比、脂肪酸与乙醇比、包合时间、包合温度及包合次数对松籽油中皮诺敛酸的影响。在单因素试验的基础上,以皮诺敛酸含量和损失率的综合分为响应值,根据Box-Behnken中心组合试验设计原理,进行优化试验设计,并建立皮诺敛酸的尿素包合回归模型。研究表明:脂肪酸:尿素=1:2. 88(g/g),脂肪酸:乙醇=1:7. 98 (g/mL),包合时间23. 44 h,包合温度4. 18℃,该条件下对皮诺敛酸进行二次包合,含量可由一次包合的39. 27%提高到53. 36%,皮诺敛酸损失率为17. 24%,综合分值为0. 954 3,综合评价指标最高。     

Production of the Carboxylate Reductase from Nocardia otitidiscaviarum in a Soluble,Active Form for in vitro Applications

Accessing aldehydes from carboxylate moieties is often a challenging task. In this regard, carboxylate reductases (CARs) are promising catalysts provided by nature that are able to accomplish this task in just one step, avoiding over-reduction to the alcohol product. However, the heterologous expression of CARs can be quite difficult due to the excessive formation of insoluble protein, thus hindering further characterization and application of the enzyme. Here, the heterologous production of the carboxylate reductase from Nocardia otitidiscaviarum (NoCAR) was optimized by a combination of i) optimized cultivation conditions, ii) post-translational modification with a phosphopantetheinyl transferase and iii) selection of an appropriate expression strain. Especially, the selection of Escherichia coli tuner cells as host had a strong effect on the final 110-fold increase in the specific activity of NoCAR. This highly active NoCAR was used to reduce sodium benzoate to benzaldehyde, and it was successfully assembled with an in vitro regeneration of ATP and NADPH, being capable of reducing about 30 mM sodium benzoate with high selectivity in only 2 h of reaction.     

肉桂油及其β-环糊精包合物对鲜切西瓜的保鲜效果

以鲜切西瓜为试材,设置肉桂油(cinnamon oil,CO)、CO-β-环糊精(β-cyclodextrin,β-CD)包合物和空白对照3个处理组,通过测定微生物和品质指标变化,研究CO及其β-CD包合物对鲜切西瓜的保鲜效果。结果表明:贮藏期间,鲜切西瓜质量损失率、菌落总数和可滴定酸质量分数呈现增加趋势,L~*值和a~*值呈现下降趋势,可溶性固形物含量先增加后下降,上述指标冷藏比常温贮藏变化缓慢;其中CO-β-CD包合物(含CO 0.040 8 g/100 g西瓜)结合4℃冷藏处理对鲜切西瓜保鲜效果最好,可以有效抑制西瓜质量损失率和可滴定酸质量分数的增加,降低西瓜褐变程度,保持西瓜较高可溶性固形物含量;冷藏4 d,该处理条件下西瓜菌落总数显著低于对照和其他处理组(P0.05),感官分数显著高于对照和CO处理组(P0.05),仍然具有商品价值。CO被β-CD包埋后稳定性提高并可以掩盖肉桂醛气味,有效维持西瓜品质,延长保质期,在鲜切西瓜保鲜上具有较好的应用前景。