COAPO-5和MnAPO-5分子筛的合成、表征及在环己烷选择氧化反应中的应用

合成一系列具有不同质量分数Co、Mn的磷铝分子筛CoAPO 5和MnAPO 5;通过X 衍射、扫描电镜、氮气物理吸附、热重分析以及紫外可见漫反射光谱等技术对分子筛的结构、形貌以及Co、Mn原子在分子筛骨架中的存在状态进行了表征;考察了氧气作氧化剂时分子筛在环己烷低温液相氧化反应中的催化性能。结果表明,所合成的CoAPO 5和MnAPO 5具有典型的AlPO4 5分子筛结构,金属Me/P比小于0.1时,分子筛结晶度较高。金属的种类、价态、质量分数及存在形式决定了模板剂与分子筛骨架作用的强度及方式,而有机模板剂的脱附、燃烧温度与这种作用密切相关;部分模板剂需在高温下脱除,说明分子筛骨架与模板剂之间存在着强相互作用。在CoAPO 5和MnAPO 5分子筛的骨架结构中,存在四配位的Co(II)和Mn(II),经过焙烧可以部分氧化为Co(III)和Mn(III),说明在焙烧样中存在着氧化还原活性中心。对于环己烷选择氧化反应,CoAPO 5和MnAPO 5分子筛都具有适中的催化活性,氧化反应产物分布均随反应时间而变化。虽然MnAPO 5的催化活性比CoAPO 5高,但其深度氧化能力也较强;采用MnAPO 5为催化剂,环己烷氧化反应的环己酮选择性及深度氧化产物的量都较高。同时,骨架Co质量分数对环己烷氧化反应活性具有显著影响,Co/P比为0.05的CoAPO 5分子筛催化活性最高,130℃反应24h,主要目的产物环己醇和环己酮的选择性可达88.5%。     

Quantification of 5-methylcytosine, 5-hydroxymethylcytosine and 5-carboxylcytosine from the blood of cancer patients by an enzyme-based immunoassay

Background

Genome-wide aberrations of the classic epigenetic modification 5-methylcytosine (5mC), considered the hallmark of gene silencing, has been implicated to play a pivotal role in mediating carcinogenic transformation of healthy cells. Recently, three epigenetic marks derived from enzymatic oxidization of 5mC namely 5-hydroxymethylcytosine (5hmC), 5-formylcytosine (5fC) and 5-carboxylcytosine (5caC), have been discovered in the mammalian genome. Growing evidence suggests that these novel bases possess unique regulatory functions and may play critical roles in carcinogenesis.

Methods

To provide a quantitative basis for these rare epigenetic marks, we have designed a biotin–avidin mediated enzyme-based immunoassay (EIA) and evaluated its performance in genomic DNA isolated from blood of patients diagnosed with metastatic forms of lung, pancreatic and bladder cancer, as well as healthy controls. The proposed EIA incorporates spatially optimized biotinylated antibody and a high degree of horseradish-peroxidase (HRP) labeled streptavidin, facilitating signal amplification and sensitive detection.

Results

We report that the percentages of 5mC, 5hmC and 5caC present in the genomic DNA of blood in healthy controls as 1.025 ± 0.081, 0.023 ± 0.006 and 0.001 ± 0.0002, respectively. We observed a significant (p < 0.05) decrease in the mean global percentage of 5hmC in blood of patients with malignant lung cancer (0.013 ± 0.003%) in comparison to healthy controls.

Conclusion

The precise biological roles of these epigenetic modifications in cancers are still unknown but in the past two years it has become evident that the global 5hmC content is drastically reduced in a variety of cancers. To the best of our knowledge, this is the first report of decreased 5hmC content in the blood of metastatic lung cancer patients and the clinical utility of this observation needs to be further validated in larger sample datasets.     

Effect of the different modifications of A1PO-5 molecular sieve on its acidity and catalytic properties in methanol conversion to hydrocarbons

An AlPO-5 molecular sieve has been isomorphously substituted by one (Co or Si) or two (Co and Si) elements and studied in the catalytic conversion of methanol to hydrocarbons. The effect of different modifications on both acidity and catalytic behavior of this material was established and further discussed.     

Reaction of 5,5-Dimethyl-2-oxotetrahydrofuran-4-ylacetohydrazide with Aldehydes and Ketones

The reaction of 5,5-dimethyl-2-oxotetrahydrofuran-4-ylacetohydrazide with a series of aldehydes and ketones led to the synthesis of systems which, according to the ¹H NMR spectra, exist exclusively in the linear form. According to the mass spectra, however, in the gas phase some of the compounds can also exist partly in the cyclic form. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 991–997, July, 2005.     

分步晶化法合成ZSM-5/SAPO-5复合材料

通过分步晶化水热处理的方式合成了ZSM-5/SAPO-5复合材料。研究了两种分子筛凝胶的混合方式、调节ZSM-5母液的酸类型、SAPO-5凝胶组成以及晶化时间对复合材料形成的影响。实验结果表明,简单将两种分子筛的合成凝胶混合不能得到复合材料。采用H₂SO₄调节ZSM-5合成母液的pH值,在ZSM-5与SAPO-5理论质量比为3.5、SAPO-5凝胶中P₂O₅与Al₂O₃摩尔比为1.2的条件下可以得到ZSM-5/SAPO-5复合材料。但样品中含有少量无定形物质,这些无定形通过延长晶化时间并不能完全消除。     

Methane to Liquid Hydrocarbons over Tungsten-ZSM-5 and Tungsten Loaded Cu/ZSM-5 Catalysts

Metal containing ZSM-5 can produce higher hydrocarbons in methane oxidation. Many researchers have studied the applicability of HZSM-5 and modify ZSM-5 for methane conversion to liquid hydrocarbons, but their research results still lead to low conversion, low selectivity and low heat resistance. The modified HZSM-5, by loading with tungsten (W), could enhance its heat resistant performance, and the high reaction temperature (800℃) did not lead to a loss of the W component by sublimation. The loading of HZSM-5 with tungsten and copper (Cu) resulted in an increment in the methane conversion as well as CO2 and C5 selectivities. In contrast, CO, C2-3 and H2O selectivities were reduced. The process of converting methane to liquid hydrocarbons (C5 ) was dependent on the metal surface area and the acidity of the zeolite. High methane conversion and C5 selectivity, and low H2O selectivity are obtained over W/3.0Cu/HZSM.     

两阶段晶化合成复合分子筛

采用低温与高温相结合的两阶段晶化方式合成了一系列ZSM-5(core)/SAPO-5(shell)双结构分子筛, 研究了合成条件对核壳结构分子筛的形成及性质的影响, 并采用X射线衍射、扫描电镜、X射线能量散射谱、红外光谱及N₂静态吸附等手段对样品进行表征. 实验结果表明, 与直接高温晶化相比, 两阶段晶化方式在短晶化时间内合成的复合材料中SAPO-5的结晶度较低, 而合成纯SAPO-5分子筛的结晶度却明显较高; 两阶段晶化的方式能适当促进核壳结构型复合分子筛的形成, 减少SAPO-5的独立生长.     

One-pot synthesis of 5-(substituted-amino)pyrazoles

An efficient and mild one-pot synthesis of substituted 5-alkylamino and/or 5-(arylamino)pyrazoles is described. A suitably decorated β-ketoamide, an aryl or alkyl hydrazine and Lawesson's reagent are suspended in THF/Py and gently heated to yield the requisite 5-aminopyrazoles.     

One-pot non-template synthesis of hierarchical ZSM-5 from kaolin source

Hierarchical ZSM-5 was synthesized without organic template and seed-assisted from the abundant natural source, kaolin, via the facile 1-step hydrothermal process. The hierarchical structure was able to be well-controlled solely on the Na₂O/Al₂O₃ ratio of the precursor. This method is not only simple but greener from the scientific point of view. As revealed, kaolin layered structure that dispersed in the highly alkaline NaOH medium prompts the formation of zeolite as the molecular organization is induced. The excess of NaOH acts as desilication agent after the formation of zeolite as proven by the ²⁹Si MAS NMR data.     

超大孔磷酸铝分子筛的合成及性能

1988年Davis等首次报道了以二正丙胺和四丁基氢氧化铵为结构导向剂合成出一种命名为VPI-5的新型磷酸铝超大孔分子筛。它是一族具有相同三维拓朴学骨架的磷酸铝系分子筛,该结构的对称性属六方晶系,P6_3cm空间群,单位晶胞由36个TO_2组成,晶胞参数α=1.8989nm,c=0.8112nm,其主孔道由18员环构成,孔直径约为1.2-1.3nm。     

Heterocyclization of ω-Bromo-2-trichloroacetyl Cycloalkanones to Isoxazole Derivatives

A new series of brominated 3,4-polymethylene-5-hydroxy-5-trichloromethyl-4,5-dihydroisoxazoles (2a–d) has been regiospecifically obtained from the reaction of ω-bromo-2-trichloroacetylcycloalkanones with hydroxylamine in 79–87% yield. Dehydration of the 5-hydroxydihydroisoxazoles 2a–d can be effected with concentrated sulfuric acid at 25 °C to give the regioisomeric brominated 3,4-polymethylene-5-trichloromethylisoxazoles (3a–d). In contrast, the dehydration of 5-hydroxydihydroisoxazoles with sulfuric acid in ethanol solution at 65 °C, for transformation of trichloromethyl to carboxyl group, was reproducible only with 9-bromo-3-trichloromethyl-3,3a,4,5,6,7,8,9-octahydrocycloocta[c]isoxazole-3-ol, 2d, leading to isoxazolecarboxylate 4d. The structural assignments of all isolated products are based on the analysis of their ¹H and ¹³C NMR spectral data.     

Vacuum Ultraviolet Photoionization and Dissociative Photoionization of Capecitabine, 50-Deoxy-5-'uorocytidine,and 50-Deoxy-5-'uorouridine

Vacuum ultraviolet (VUV) photoionization and dissociative photoionization of capecitabine and its metabolites, 5'-deoxy-5-fluorocytidine (5'-DFCR) and 50-deoxy-5- fluorouridine (5'-DFUR), were investigated with infrared laser desorption/tunable synchrotron VUV pho-toionization mass spectrometry. Molecular ions (M+) with small amounts of fragments can be found for these compounds at relatively low photon energies, while more fragment ions would be produced by increasing the photon energies. (M-H₂O)⁺, (base+H)⁺, (base+2H)⁺,(base+30)⁺, (base+60)⁺, and sugar moiety were proposed for these nucleoside drugs with similar backbones. Decomposition channels for the major fragments were discussed in de-tail. Moreover, ab initio calculations were introduced to study the dehydration pathways of three fluoro-nucleosides. Corresponding appearance energies for the (M-H₂O)⁺ ions were computed.     

液相色谱-串联质谱法同时测定生物组织全基因组DNA甲基化和羟甲基化水平

测定全基因组DNA甲基化和羟甲基化水平对于研究环境污染物暴露的影响及致病机理具有重要的作用。本文建立了液相色谱-串联质谱（LC-MS/MS）同时测定动物组织中全基因组DNA甲基化和羟甲基化水平的方法。从动物组织样品中提取DNA,并将其酶解成单核苷,利用液相色谱-串联质谱法测定5-甲基胞嘧啶核苷、5-羟甲基胞嘧啶核苷和鸟嘌呤核苷的含量,计算全基因组DNA甲基化率和羟甲基化率。利用该方法研究了砷暴露对大鼠肝脏和小脑全基因组DNA甲基化和羟甲基化水平的影响,得到了砷影响DNA甲基化及羟甲基化的初步数据。该方法具有良好的重现性、灵敏度和稳定性,可以同时检测差异较大的DNA甲基化和羟甲基化水平。为同时研究DNA甲基化和羟甲基化水平提供了有力的支持。     

制备沸石基纳米非晶软磁材料的新方法及其磁性

首次以分步水热合成封装法于孔径分别为0.56,0.73和0.78nm的沸石ZSM-5,Naβ和NaY的孔道中成功地封装了强磁性材料SmCo₅和铁氧体Fe₃O₄,并测得其磁滞回线及饱和磁化强度M_s,剩余磁化强度M_r和矫顽力H_c.实验结果表明,体相Fe₃O的矫顽力为8117A/m.封装后减小至1114A/m;体相SmCo₅的矫顽力为55863A/m,封装后减小至5491A/m,即由体相强磁性材料变为纳米非晶软磁材料,这是纳米粒子的小尺寸效应和量子尺寸效应所致.并由XRD,IR和磁滞回线对该材料进行了表征.     

在β-环糊精和阳离子表面活性剂作用下5-Br-TADEB 分光光度法测定微量铑

研究了在 β-环糊精 ( β- CD)和各种不同类型表面活性剂存在下 5-溴 - ( 2 -噻唑偶氮 ) - 5-二乙氨基苯甲酸 ( 5- Br- TADEB)与铑的显色反应。在 p H 4.0～5.7的 HAc- Na Ac介质中 ,Rh3 +与 5- Br- TADEB形成稳定的 1∶ 2蓝色络合物 ,最大吸收波长位于 687nm处。阴离子和非离子表面活性剂对体系无明显作用 ,β- CD和阳离子表面活性剂分别加入使体系灵敏度提高 2 0 % ,而当 β- CD与阳离子表面活性剂同时加入则可使体系灵敏度提高 50 % ,其表观摩尔吸光系数ε=1 .1 4× 1 0 5L·mol-1·cm-1。该方法已用于含铑催化剂中微量铑的测定     

添加锡组分对Pt/ZSM-5催化剂丙烷脱氢反应性能的影响

丙烷脱氢制丙烯是优化利用炼厂气和油田伴生气资源的一条重要途径,这方面的研究已日益引起研究者的关注[1～5].对γ-Al2O3为载体的负载型铂催化剂丙烷脱氢催化性能已进行了深入的研究.通过引入特定的助剂,可以提高负载型铂催化剂低碳烷烃脱氢选择性和稳定性[6,7].与Ce、Zn、V、La、Cr、Fe、Zr、Mn等助剂比较,Sn助剂更有利于提高催化剂丙烷脱氢的反应稳定性[8].     

H-ZSM-5分子筛上苯与乙醇和乙烯烷基化反应的理论研究

采用ONIOM2(B3LYP/6-31G(d):UFF)计算方法研究了H-ZSM-5分子筛上苯与乙醇和乙烯烷基化反应历程.选取40T簇模型模拟了H-ZSM-5分子筛位于孔道交叉点的酸性位.从生成能和反应活化能角度分析并比较了苯与乙醇和乙烯烷基化反应机理.结果表明,苯与乙醇的烷基化按照分步机理进行,速控步骤的活化能为170.34 kJ/mol.而乙烯作为烷基化剂与苯反应时同时存在联合机理和分步机理,且二者之间存在一定程度的竞争,其中联合机理的活化能为167.24 kJ/mol,分步机理速控步骤的活化能为155.20 kJ/mol.比较苯与乙醇和乙烯发生烷基化反应的机理可以看出,二者作为烷基化试剂对烷基化反应性能影响不大.     

铝和硅元素掺杂对LaNi5电子结构影响的研究

采用第一原理离散变分法（DVM）研究了常用元素Al和Si掺杂对稀土系贮氢合金LaNi5电子结构的影响，在计算结果的基础上进一步探讨了微观结构对合金宏观性能的影响。分析结果表明：进入八面体间隙的H原子主要与LaNi5合金中非氢化物形成元素M和Ni发生较强的相互作用．而H原子与合金中的氢化物形成元素La的相互作用很弱。同时Al和Si两种掺杂元素对LaNi5合金性能的影响基本相似。     

Photochemical reactions of 5-fluoropyrimidine bases with selected alkylamines

Novel photochemical reactions between 5-fluoropyrimidine bases and primary alkylamines are described. Photoreaction of 5-fluorouracil with alkylamines in aqueous solution (pH>8) leads to 5-alkylaminouracils as the main photoproducts. Similarly, photoreaction of 5-fluorocytosine with alkylamines yields 5-alkylaminocytosines.     

ZSM-5分子筛催化1-己烯生成cis-2-己烯的理论研究

基于54T团簇模型, 采用ONIOM分层计算方法, 研究了1-己烯在ZSM-5分子筛上进行顺式双键异构的反应机理. 计算结果表明, 1-己烯的顺式双键异构反应通过只有分子筛Brønsted酸部分起作用的机理进行. 首先, 1-己烯与分子筛的Brønsted酸性位形成π配位复合物. 接着, 酸质子发生迁移使1-己烯的双键端基碳原子被质子化, 同时双键的另一碳原子与失去质子的Brønsted酸羟基的氧原子成键, 形成稳定的烷氧基中间体. 然后, 烷氧基中间体中的C―O共价键被打断, 同时Brønsted酸羟基的氧原子从C₆H₁₃基团提取一个氢原子还原分子筛的酸性位, 并且生成cis-2-己烯. 这一反应路径与借助于分子筛活性位的酸-碱双功能性质的反应路径是相互竞争的. 计算得到的表观活化能是59.37 kJ·mol^-1, 该值与实验值非常接近. 这一结果合理解释了双键异构过程中的能量特征, 并且扩展了对分子筛活性位本质的理解.