Ni-Mo2N/SiO2复合纳米催化剂的制备及其对四氢萘加氢的催化活性

采用程序升温氮化法制备了Mo2N/SiO2,在此基础上负载Ni盐,制备了Ni-Mo2N/SiO2复合纳米催化剂,并考察了催化剂对四氢萘加氢的催化活性.结果表明,与Ni2Mo3N/SiO2及Ni/SiO2催化剂相比,Ni-Mo2N/SiO2复合催化剂具有较高的催化活性.采用"分离床"方法研究了Ni和Mo2N对四氢萘加氢活性的影响.通过X射线粉末衍射、透射电镜、氢吸附、元素分析和比表面积测定等技术对Ni-Mo2N/SiO2催化剂进行了表征.结果表明,与Ni/SiO2催化剂相比,Ni-Mo2N/SiO2复合催化剂中Ni的分散度并未提高;催化活性的提高归因于Ni与Mo2N在四氢萘加氢中的协同作用.氮化物的引入增加了芳烃吸附活性位的数目.提出了四氢萘在Ni-Mo2N/SiO2催化剂上的可能加氢机理.     

基于石墨烯-壳聚糖-辣根过氧化物酶的H2O2生物传感器的研制

制备了石墨烯-壳聚糖(GR-CS)纳米复合材料,并将之与辣根过氧化物酶(HRP)混合,构建了基于石墨烯-壳聚糖-辣根过氧化物酶的生物传感器(GR-CS-HRP/GC)。探针及循环伏安研究表明,该界面具有优异的电子传导能力、较大的比表面积和良好的生物相容性,对H2O2的还原显示出较好的电催化活性,在工作电位为-0.2 V,0.05 mol/L的磷酸盐缓冲盐溶液(PBS,pH 6.8)中,该酶传感器对过氧化氢响应灵敏度高,检测范围宽,测定H2O2的线性范围为5.0×10-7～2×10-3mol/L(相关系数为0.998)。检出限为2.0×10-7mol/L(S/N=3)。并且表现出良好的稳定性和高选择性。该电极用于实际样品中H2O2的测定,结果令人满意。     

Automated measurement system for H2O2 in the atmosphere by diffusion scrubber sampling and HPLC analysis of Ti(IV)-PAR-H2O2 complex

An automated selective measurement system for monitoring hydrogen peroxide (H2O2) in the atmosphere was developed (using a diffusion scrubber coupled to a high performance liquid chromatography) due to the importance of H2O2 in understanding tropospheric chemistry and its harmful effects on vegetation. H2O2 in the atmosphere was effectively collected by a diffusion scrubber, which consisted of a hydrophobic porous polytetrafluorethylene (PTFE) tube positioned concentrically within a Pyrex glass tube. Titanium(IV)-4-(2-pyridylazo)resorcinol (Ti(IV)-PAR) solution acidified at pH 2.2 was used as the scrubbing solution for the diffusion scrubber. After the collection of the air sample by the diffusion scrubber, the pH value of the Ti(IV)-PAR scrubbing solution was adjusted to pH 11.9 to form a stable complex of Ti(IV)-PAR-H2O2. An aliquot of the sample solution was injected into a high performance liquid chromatograph equipped with a semi-micro-reversed-phase column and a spectrophotometric detector set at 508 nm for separating and determining the Ti(IV)-PAR-H2O2 complex. The automated measurement could be performed at 60 min intervals. The collection efficiency of H2O2 was higher than 98% at an air flow rate of 1.0 l min-1. The detection limit (3 sigma of the blank value) of H2O2 was 9 parts per trillion by volume (pptv) for an air sampling volume of 55.1. The interference from coexisting O3 or SO2 in the atmosphere was negligible during the collection of H2O2 by the diffusion scrubber. The developed automated measurement system was suitable for monitoring H2O2 in the atmosphere.     

静电纺丝方法制备a2-K8 P2W17 MnO61纳米纤维

运用高压静电纺丝和程序升温焙烧的方法制备了a2-K8P2W17MnO61纳米纤维．通过红外光谱（FT-IR）和X射线粉末衍射（XRD）对纤维进行了表征．结果表明，制备的纳米纤维为纯杂多酸盐a2—K8P2W17MnO61,扫描电子显微镜（SEM）图形显示焙烧后获得纳米纤维的平均直径大约为140nm。     

Gas chromatographic determination of 2-ethylhexanoic acid in urine as its pentafluorobenzyl ester

A gas chromatographic (GC) method was developed for the determination of 2-ethylhexanoic acid (2-EHA), initially in the urine of animals, but subsequently in samples of urine from sawmill workers in order to evaluate their exposure to 2-EHA which is used as a wood preservative. The 2-EHA was derivatised to the pentafluorobenzyl ester, which was then analysed by means of a cross-linked methyl silicone GC column with electron capture detection. Gas chromatography-mass spectrometry was used to confirm the identity of the GC peaks. The analytical range of the method was 0.03-2.70 mmol of 2-EHA per mol of creatinine in urine and the limit of detection was 0.01 mmol per mol of creatinine. The recovery of 2-EHA was 81-90% with a coefficient of variation of 9.8%. The amount of 2-EHA excreted in urine was corrected for the excretion of creatinine. The concentration of 2-EHA in the urine of the workers studied varied from 0.01 to 5.40 mmol per mol of creatinine; the median was 0.1 mmol per mol of creatinine.     

Encapsulation and dynamic behavior of two H2 molecules in an open-cage C70

An open-cage C70 derivative having a 13-membered ring opening (2) was synthesized by a three-step reaction; thermal reaction of C70 with a pyridazine derivative, oxidative cleavage of the CC double bond, and insertion of a sulfur atom to the opening. The structure of 2 was determined by X-ray analysis. One H2 molecule was introduced into 2 to give H2@2 in 97% yield. Furthermore, two H2 molecules were encapsulated in 2 in 3% yield. The positional exchange of two H2 molecules inside 2 was clearly observed by the dynamic low-temperature NMR measurements.     

Et2NH2[Nd(S2CNEt2)4]的晶体结构和生成反应焓变

在干燥氮气气氛下,以无水乙醇为溶剂,制备了低水合氯化钕与二乙氨基荒酸二乙铵(D-DDC)配合物,确定其组成为Et2NH2[Nd(S2CNEt2)4].单晶结构分析表明,配合物中4个二乙氨基荒酸根各通过2个硫原子与钕离子成键形成八配位十二面体阴离子,并与二乙铵阳离子形成缔合型分子.晶体属单斜晶系,空间群P21/n,a=1.37517(14)nm,b=2.1146(2)nm,c=1.44641(15)nm,β=102.028(2)°,Z=4.用微量热法测定了298.15K下水合氯化钕和D-DDC在无水乙醇中的溶解焓及二乙氨基荒酸钕液相生成反应焓变分别为(-17.89±0.096),(50.280±0.151)和(-10.116±0.065)kJ/mol,求得固相生成反应焓变.     

单斜层状LiMnO2的球磨-离子交换法合成及其电化学性能研究

通过球磨促进固相反应法合成出了具有单斜层状结构的前驱物NaMnO₂，随后通过离子交换得到了单斜层状LiMnO₂。XRD测试结果显示产物为单相。扫描电镜(SEM)和透射电镜(TEM)观测结果显示LiMnO₂的粒子尺寸为300～500 nm，HRTEM分析显示干扰条纹的间距为0.485 nm，基本对应于m-LiMnO₂的(001)晶面间距。红外吸收光谱(IR)和X射线光电子能谱(XPS)被用来测量m-LiMnO₂中Mn-O键的伸缩和弯曲振动吸收和Mn元素的价态。合成的m-LiMnO₂在电化学充放电循环初期表现了较好的电化学性能，但其循环寿命仍需要进一步改善。     

Direct determination of horseradish peroxidase encapsulated in liposomes by using luminol chemiluminescence.

Horseradish peroxidase (HRP) encapsulated in liposomes was directly detected by using luminol chemiluminescence (CL) with H2O2 without lysis of liposomes. At a low concentration of H2O2, the initial rate of HRP-catalyzed luminol CL in liposomes was slower than that of HRP-catalyzed luminol CL in a lipid-free bulk solution. The decrease in the initial rate of the CL reaction in liposomes was due to the membrane permeation of luminol and H2O2. At a high concentration of H2O2, the initial rate of the CL reaction in liposomes was the same as that in a lipid-free bulk solution. The CL measurement conditions in both a lipid-free bulk solution and in liposomes were optimized in the concentrations of luminol and H2O2 by measuring the CL response curves, in which only one peak appeared and the CL intensity was maximal. The CL intensity observed in HRP-catalyzed luminol CL in liposomes was a factor of seven greater than that observed in a lipid-free bulk solution. The CL intensity was dependent on the amount of HRP-encapsulated liposomes used. The detection limit in the direct detection of HRP encapsulated in liposomes was sensitive by a factor of 3 compared with that in HRP-catalyzed luminol CL in a lipid-free bulk solution.     

A new thermostable peroxidase from garlic Allium sativum

Analysis of peroxidase activity by native polyacrylamide gel electrophoresis (PAGE) from a garlic bulb (Allium sativum L) extract showed two major activities (designated POX1 and POX2). The POX2 isoenzyme was purified to homogeneity by ammonium sulfate precipitation, gel filtration, and cation-exchange chromatography. The purified enzyme was found to be monomeric with a molecular mass of 36.5 kDa, as determined by sodium dodecyl sulfate-PAGE. The optimum temperature ranged from 25 to 40 degrees C and optimum pH was about 5.0. The apparent Km values for guaiacol and H2O2 were 9.5 and 2 mM, respectively. POX2 appeared highly stable since 50% of its activity was conserved at 50 degrees C for 5 h. Moreover POX2 was stable over a pH range of 3.5-11.0. Immobilization of POX2 was achieved by covalent binding of the enzyme to an epoxy-Sepharose matrix. The immobilized enzyme showed great stability toward heat and storage when compared with soluble enzyme. These properties permit the use of this enzyme as a biosensor to detect H2O2 in some food components such as milk or its derivatives.     

直接由SiO_2低温合成含硅聚氨酯及其结构表征

有机硅材料是一类应用非常广泛的材料,但这些产品所用基本原料几乎都来源于石英沙(SiO2)的高温碳热还原[1],这个方法已大规模的工业化,但它的高能耗、高腐蚀成为人们越来越关注的问题.1991年美国Laine[2]直接以SiO2为原料成功地制备了五配位、六配位有机硅化合物,并进一步合成了导电材料和高性能陶瓷[3～7].我们实验室自1995年以来,在Laine的基础上,发现如果以沙子为原料,则产率非常低,即使在超声波作用下,反应一周合成的五配位硅化合物其产率不足10%,这可能是由于沙子的晶型非常完美,在200℃下很难打破Si-O键生成配位硅,如果以无定型SiO2为原料(如白碳黑,稻壳灰等),合成的五配位硅其产率几乎为100%,而且反应时间缩短为4h.然后以高活性的五配位硅为原料制备了一系列的含硅有机物,如与环氯丙烷反应[8],不仅消除了五配位硅化合物的水解可逆性反应,中和了它的强碱性,而且把环氧基团接到了配位硅化合物上,生成了一种非常类似于液态环氧树脂的淡黄色的粘稠状液体.我们按Laine的路线,向含硅聚合物方向发展[9].本文合成的双羟基四配位硅单体是五配位硅钾化合物向含硅聚合物转化的关键,由于其结构带有两个活泼羟基,可以和二元酰氯、二元羧酸、二异氰酸酯、导氰酸酯基封端的聚醚或异氰酸酯基封端的聚酯进行缩聚反应,合成主连含硅的聚合物.     

氯柱硼镁石在87 ℃水中的溶解及相转化动力学

对氯柱硼镁石(2MgO•2B2O3•MgCl2•14H2O)在87 ℃水中的溶解转化进行了动力学考察.通过对不同时间取出液样的化学分析和不同阶段分离的固相IR和XRD鉴定表明：其高温区溶解转化不同于低温,氯柱硼镁石很快溶脱掉MgCl2,形成晶形的MgO•B2O3•4H2O中间产物,最终转化产物柱硼镁石（MgO•B2O3•3H2O）,是由MgO•B2O3•4H2O脱水后从溶液中大量析出的.提出了溶解及相转化机理,拟合出转化结晶动力学方程.     

An Easy Synthesis of Monofluorinated Derivatives of Pyrroles from β-Fluoro-β-Nitrostyrenes

The catalyst-free conjugate addition of pyrroles to β-Fluoro-β-nitrostyrenes was investigated. The reaction was found to proceed under solvent-free conditions to form 2-(2-Fluoro-2-nitro-1-arylethyl)-1H-pyrroles. The effectiveness of this approach was demonstrated through the preparation of a series of the target products in a quantitative yield. The kinetics of a conjugate addition of pyrrole was studied in detail to reveal the substituent effect and activation parameters of the reaction. The subsequent base-induced elimination of nitrous acid afforded a series of novel 2-(2-Fluoro-1-arylvinyl)-1H-pyrroles prepared in up to an 85% isolated yield. The two-step sequence herein proposed is an indispensable alternative to a direct reaction with elusive and unstable 1-Fluoroacetylenes.     

中孔TiO_2的制备与表征

以聚氧乙烯十二烷基醚为模板剂,钛酸四丁酯为钛源制备了中孔TiO2,探讨了焙烧温度和掺杂对中孔TiO2结构的影响。利用XRD,TEM,FT-IR和N2吸附等对其结构进行了表征。结果表明,中孔TiO2具有较大的孔径和较高的热稳定性;钇掺杂使中孔TiO2的比表面积和孔体积增大及热稳定性提高。以噻吩加氢脱硫为探针反应,考察了以中孔TiO2为载体的N i基催化剂的催化活性,钇掺杂能提高其催化活性。     

Uptake of transition metal ions using liposomes containing dicetylphosphate as a ligand.

The uptake of Cu2+ was investigated using various types of liposomes composed of phosphatidylcholine (PC), cholesterol (Chol) and dicethylphosphate (DCP). DCP played a role as a ligand for Cu2+. Multilamellar vesicles (MLVs) were more effective for the uptake of Cu2+ compared to unilamellar vesicles prepared by the extrusion technique. The uptake efficiency of MLVs for Cu2+ was dependent on the molar ratio of DCP in MLVs. The uptake percent of Cu2+ was 92% using MLVs having a PC:DCP:Chol molar ratio of 4:3:3; 95% of the total vesicle Cu2+ was bound to DCP of the outer membrane surface of the MLVs, and the remaining 5% of the total Cu2+ was distributed into the interior side of the MLVs. MLVs having a PC:DCP:Chol molar ratio of 4:3:3 were also effective as separation media for Mn2+, Co2+, Ni2+ and Zn2+. The uptake efficiency of the MLVs for the transition-metal ions increased in the order Co2+ < Zn2+ < Ni2+ < Mn2+ < Cu2+.     

复合模板剂下有序介孔TiO2的制备研究

在复合模板剂聚氧乙烯十二烷基醚(Brij35）和聚乙二醇（PEG)下，制备出有序介孔TiO2.用XRD、HRTEM、SEM、FT-IR和N2吸附脱附等方法进行表征；并通过对反应过程中电导率和粘度的连续监测，分析有序介孔TiO2形成过程.研究表明,介孔TiO2为规整的六方排列结构，在低于400 ℃焙烧，有序结构稳定性高，比表面积达252 m2•g－1，孔径3.4 nm，晶型为锐钛矿；经500 ℃焙烧，有序介孔结构破坏，并开始出现金红石型晶相.有序介孔TiO2形成过程是基于在高极性介质中非极性的碳氢链聚集成为胶束，同时钛酸丁酯（TBOT）在已形成的胶束上聚集，在酸作用下不断水解缩聚而形成有序介孔结构，有效控制水解和聚合过程是控制介孔材料结构形成的关键.     

Synthesis of enantiomerically pure C2-branched-2-deoxy-heptitols

2,3; 4,5-Di-O-isopropylidene-al- -(+)-arabinose 1a reacts with di-l-menthylmalonate to give the hepturonates 2a and 3a in a manno-glaco 7.8:2.2 ratio. The C-2 branched 2-Deoxy-2-hydroxy-methyl- -manno-heptitol 6 and 2-Deoxy-2-hydroxy-methyl- -gluco-heptitol 7 were obtained by submitting 2a and 3a to routine procedures. When the same reaction was performed with di-d-menthylmalonate a 3.5:6.5 mixture of 2b and 3b was obtained. A 8.2:1.8 anti-diastereosetectivity was also observed by reacting 2,3,4,5-O-tetraacetyl-al- -(−)-arabinose 1b with di-d-menthylmalonate. The absolute stereochemistry of the major hepturonate 10 obtained in this reaction was secured by a single crystal X-ray analysis.     

Enhanced remote photocatalytic oxidation on surface-fluorinated TiO2

The mobile nature of active oxygen species generated on the UV-illuminated TiO2 surface is now well-recognized. Surface oxidants not only migrate two-dimensionally but also desorb from the surface to be air-borne oxidants. The remote photocatalytic oxidation (PCO) of stearic acids over the surface-fluorinated TiO2 (F-TiO2) film was carried out in the ambient air to study the effects of fluorination on the desorption of oxidants from the surface. The F-TiO2 film was faced to a stearic acid-coated glass plate separated by a small gap (typically 30 microm), and the photocatalytic degradation of the stearic acid was monitored by Fourier transform infrared measurement or gas-chromatographic CO2 production analysis. Remote photocatalytic degradation of stearic acids was markedly faster with F-TiO2 than with the pure TiO2 film, which indicates that the generation of air-borne oxidants is enhanced over the F-TiO2 surface. The remote PCO activity was higher with a higher surface fluoride concentration, higher UV intensity, and smaller gap. The remote photocatalytic activity of F-TiO2 was maximal at a relative humidity of 50% and did not show any sign of deactivation with repeated reactions. The production of CO2 that evolved as a result of the remote PCO of stearic acids was enhanced when H2O2 vapor was present but was strongly inhibited in the presence of ammonia gas that should scavenge OH radicals. Judging from various evidences, the air-borne oxidants in remote PCO are most likely OH radicals and the surface fluorination of TiO2 seems to facilitate the desorption of OH radicals.     

低温等离子体与MnO_x/γ-Al_2O_3协同催化降解正己醛

研究了在低温等离子体和催化剂共同作用下低浓度正己醛的降解反应.结果表明,等离子体与γ-Al2O3之间产生了很好的催化协同作用,在低放电功率(2.8W)和低温(80℃)下,干燥空气气氛中,γ-Al2O3对0.12%正己醛的去除率为87.1%;当γ-Al2O3负载7.5%MnOx后,正己醛去除率达到96.5%,其效果与Pt/γ-Al2O3相当.7.5%MnOx/γ-Al2O3在实验条件下连续使用50h,其催化活性未见下降.     

稀土氧硫化物上的羰基硫水解反应

研究了一种新型的羰基硫水解催化剂--稀土氧硫化物.考察了稀土系列氧化物硫化后的水解活性,发现其活性顺序为La≈Pr≈Nd≈Sm>Eu>Ce>Gd≈Ho>Dy>Er.XRD物相分析表明,各种稀土氧化物经水合及硫化后呈现出不同的物相变化特性,稀土氧硫化物是COS水解的活性物质.在氧硫化镧和氧硫化钕催化剂上研究了O₂和SO₂对羰基硫水解反应的影响,与传统的氧化铝基和氧化钛基水解催化剂相比,稀土氧硫化物显示出良好的抗氧化性能,而SO₂对催化活性的影响是可逆的.