Improvement of catalytic activity and sulfur-resistance of Ag/TiO2–Al2O3 for NO reduction with propene under lean burn conditions

Ag-based catalysts supported on various metal oxides, Al₂O₃, TiO₂, and TiO₂–Al₂O₃, were prepared by the sol–gel method. The effect of SO₂ on catalytic activity was investigated for NO reduction with propene under lean burn condition. The results showed the catalytic activities were greatly enhanced on Ag/TiO₂–Al₂O₃ in comparison to Ag/Al₂O₃ and Ag/TiO₂, especially in the low temperature region. Application of different characterization techniques revealed that the activity enhancement was correlated with the properties of the support material. Silver was highly dispersed over the amorphous system of TiO₂–Al₂O₃. NO₃⁻ rather than NO₂⁻ or NOx reacted with the carboxylate species to form CN or NCO. NO₂ was the predominant desorption species in the temperature programmed desorption (TPD) of NO on Ag/TiO₂–Al₂O₃. More amount of formate (HCOO⁻) and CN were generated on the Ag/TiO₂–Al₂O₃ catalyst than the Ag/Al₂O₃ catalyst, due to an increased number of Lewis acid sites. Sulfate species, resulted from SO₂ oxidation, played dual roles on catalytic activity. On aged samples, the slow decomposition of accumulated sulfate species on catalyst surface led to poor NO conversion due to the blockage of these species on active sites. On the other hand, catalytic activity was greatly enhanced in the low temperature region because of the enhanced intensity of Lewis acid site caused by the adsorbed sulfate species. The rate of sulfate accumulation on the Ag/TiO₂–Al₂O₃ system was relatively slow. As a consequence, the system showed superior capability for selective adsorption of NO and SO₂ toleration to the Ag/Al₂O₃ catalyst.     

化工易爆场所电气设备选型和应用

介绍了防爆电气设备所应用的场所和环境,防爆电气设备的选型原则,防爆电气设备所分的种类,阐述了在不同性质的爆炸危险场所和环境应选用不同的防爆电气设备。     

不明原发灶的颈部淋巴结转移癌的治疗探讨(附25例报告)

目的探讨不明原发灶的颈部转移癌的治疗方式。方法回顾分析我院2003～2009年收治的25例不明原发灶的颈部淋巴结转移癌的病例资料,采用治疗方法为手术(S)、放疗(R)、化疗(C)、手术加放疗(S+R)、手术加化疗(S+C)、放化疗(R+C),手术加放化疗(S+R+C)。结果全组5年总生存率为48%,其中转移性低分化癌的治疗方式为以手术+放疗为主,转移性鳞癌则以手术+化疗为主,转移性腺癌以手术+化疗为主,其中的乳头状腺癌采用甲状腺癌联合根治术式,锁骨上区转移癌以化疗及放疗为主。结论对原发灶不明的颈部转移癌的治疗,应根据淋巴结转移的部位、N分期、病理类型及患者的身体状况等多种因素决定,应选择综合治疗。     

1,4-二(5,5-二甲基-1,3-二氧杂己内磷酰亚胺基)苯的合成

对以新戊二醇、三氯氧磷和对苯二胺为原料,在三乙胺和４ Ｎ,Ｎ 二甲胺基吡啶（ＤＭＡＰ）催化作用下合成１,４ 二（５,５ 二甲基 １,３ 二氧杂己内磷酰亚胺基）苯（ＮＢＰＡＮ）的反应进行了研究。讨论了ＤＭＡＰ对该反应的作用机制,合成收率达８２．７％。并用元素分析、ＩＲ和１ＨＮＭＲ表征了产物的结构。热重分析表明ＮＢＰＡＮ的起始分解温度为２８０℃,并在２８０～３１０℃迅速炭化,成炭率达３５．５８％。     

木瓜蛋白酶对MPA诱导的单核细胞分泌和黏附功能的抑制作用及分子机制初步研究

目的: 观察木瓜蛋白酶对单核细胞-血小板聚集物（MPA）诱导的单核细胞分泌和黏附功能的抑制作用,并初步探讨其分子机制。方法: 分离人外周血单核细胞和富血小板血浆（PRP）,检测20 U/L木瓜蛋白酶不同作用方式下凝血酶和花生四烯酸（AA）诱导的MPA形成及肿瘤坏死因子-α（TNF-α）水平。将实验分为0（对照）、20、80 U/L木瓜蛋白酶组,分别以ELISA、流式细胞术和显微镜检查测定木瓜蛋白酶与单核细胞共孵育后MPA诱导的单核细胞趋化蛋白-1（MCP-1）和组织因子（TF）释放、CD11b和CC趋化因子受体2（CCR2）表达水平以及单核细胞与人脐静脉内皮细胞黏附率,再以Western blot检测单核细胞Akt磷酸化（p-Akt）和环氧化酶-2（COX-2）表达水平。结果: 20 U/L木瓜蛋白酶与单核细胞和血小板共孵育时显著降低凝血酶和AA诱导的MPA形成和TNF-α 水平（P<0.01）。20 U/L木瓜蛋白酶组MCP-1和TF水平,CD11b和CCR2表达率,单核细胞与内皮细胞黏附率均显著低于对照组（P<0.01）,80 U/L组对五者的抑制率显著高于20 U/L组（P<0.01）。木瓜蛋白酶显著抑制p-AKT和COX-2表达,80 U/L组p-Akt和COX-2光密度比值显著低于20 U/L组（P<0.01）。结论:木瓜蛋白酶可通过抑制Akt磷酸化和COX-2表达途径而抑制MPA诱导单核细胞活化后的释放和黏附功能,从而可能有助于预防动脉粥样硬化。     

Quest for the Crypto-phosphoproteome

Protein phosphorylation is one of the most studied post-translational modifications (PTMs). Despite the remarkable advances in phosphoproteomics, a chemically less-stable subset of the phosphosites, which we call the crypto-phosphoproteome, has remained underexplored due to technological challenges. In this Viewpoint, we briefly summarize the current understanding of these elusive protein phosphorylations and identify the missing pieces for future studies.     

The Histidine Phosphocarrier Kinase/Phosphorylase from Bacillus Subtilis Is an Oligomer in Solution with a High Thermal Stability

The histidine phosphocarrier protein (HPr) kinase/phosphorylase (HPrK/P) modulates the phosphorylation state of the HPr protein, and it is involved in the use of carbon sources by Gram-positive bacteria. Its X-ray structure, as concluded from crystals of proteins from several species, is a hexamer; however, there are no studies about its conformational stability, and how its structure is modified by the pH. We have embarked on the conformational characterization of HPrK/P of Bacillus subtilis (bsHPrK/P) in solution by using several spectroscopic (namely, fluorescence and circular dichroism (CD)) and biophysical techniques (namely, small-angle X-ray-scattering (SAXS) and dynamic light-scattering (DLS)). bsHPrK/P was mainly a hexamer in solution at pH 7.0, in the presence of phosphate. The protein had a high conformational stability, with an apparent thermal denaturation midpoint of ~70 °C, at pH 7.0, as monitored by fluorescence and CD. The protein was very pH-sensitive, precipitated between pH 3.5 and 6.5; below pH 3.5, it had a molten-globule-like conformation; and it acquired a native-like structure in a narrow pH range (between pH 7.0 and 8.0). Guanidinium hydrochloride (GdmCl) denaturation occurred through an oligomeric intermediate. On the other hand, urea denaturation occurred as a single transition, in the range of concentrations between 1.8 and 18 µM, as detected by far-UV CD and fluorescence.     

选择性絮凝的方法及其机理(I)——增加或减少颗粒上的活性质点数法

选择性絮凝现有方法的分类可从吸附角度和动力角度两个大方面考虑。着重介绍从吸附角度考虑的增减颗粒上的活性质点数的方法,它包括选择合适的絮凝剂官能团、改变颗粒表面电位法、使用选择性分散剂法和近年来开发的SBA(质点阻塞剂)法等一些常用的方法。也对选择性絮凝方法的机理和分类规律进行了阐述。     

Adsorption behavior and mechanism of Bi(III) ions on rutile–water interface in the presence of nonyl hydroxamic acid

The adsorption behavior and mechanism of Bi(III) ions on the rutile–water interface were investigated through micro-flotation, Zeta potential measurement, adsorption amount measurement and X-ray photoelectron spectroscopy (XPS). According to the results of micro-flotation, Bi(III) ions could largely improve the rutile flotation recovery (from 62% to 91%), and they could increase the activating sites and reduce the competitive adsorption between nonyl hydroxamic acid negative ions and OH^? ions, which determined that Bi(III) ions were capable of activating rutile flotation. The adsorption of Bi(III) ions onto the rutile surface led to the shift of Zeta potential into the positive direction, which was good for the adsorption of nonyl hydroxamic acid anions. In addition, the results of XPS indicated that the chemical environment around Ti atom had not changed before and after the adsorption of Bi(III) ions. Based on the adsorption mechanism of Bi(III) ions, it was deduced that firstly Bi(III) ions occupied the vacancies of the original Ca²⁺, Mg²⁺ and Fe²⁺ ions on the rutile surface; secondly Bi(III) ions covered on the rutile surface in the form of hydroxides.     

Multifunctional heteroatom zeolites: construction and applications

Multifunctional heteroatom zeolites have drawn broad attentions due to the possible synergistic effects in the catalytic reactions. Remarkable achievements have been made on the synthesis, characterization and catalytic applications of multifunctional heteroatom zeolite, while a review on this important topic is still missing. Herein, current research status of multifunctional heteroatom zeolites is briefly summarized, aiming to boost further researches. First, the synthesis strategies toward heteroatom zeolites are introduced, including the direct synthesis and postsynthesis routes; then, the spectroscopic techniques to identify the existing states of heteroatom sites and the corresponding physiochemical properties are shown and compared; finally, the catalytic applications of multifunctional heteroatom zeolites in various chemical reactions, especially in one-step tandem reactions, are discussed.