基于愈创木酚荧光减量准确测定过氧化物酶活性的新方法

利用H2O2/过氧化物酶(POD)/愈创木酚(GA)反应体系的产物(470 nm)吸光度去定量POD活性是目前常用方法之一,但产物不稳定且对比色皿有吸附现象是该反应的主要缺点之一。为了解决此问题,本研究利用GA的荧光特性建立了一种能准确测定POD活性的方法。用辣根过氧化物酶( HRP)作为测试样品得到了以下优化条件：0.5 mmol/L GA,0.5 mmol/L H2O2,0.05 mol/L PBS缓冲液(pH 6.0),反应温度20℃,样品耗量20μL;本方法的线性范围为500~60000 U/L(r=0.9993),RSD≤2.4%(n=11),检出限为385 U/L。在优化条件下,用白萝卜提取液作为测试样品,用本方法((9714依132) U/L)与比色法((9926依352) U/L)和循环催化流动分析法((9608依456) U/L)进行了对比,结果表明,3种方法相互一致性很好。     

在Al-P-Ti-Si-O催化剂上由甲醇和邻苯二酚合成愈创木酚的研究

采用非均匀沉淀法制备了Al1P1.30TiaSib(a=0-0.51,b=0-0.90）复合催化剂,研究了邻苯二酚与甲醇在该催化剂上的气相o-甲基化反应。结果表明,催化剂组成、相结构和表面性质对催化剂的活性和选择性有很大影响。其中Al1P1.30Ti0.30si0.17催化剂的愈创木酚收率最高,在反应温度为553K时,邻苯二酚转化率和愈创木酚收率分别为92%和86%。     

薄层色谱法在香兰素合成中的应用

应用薄层色谱法对愈创木酚、3－甲氧基－4－羟基扁桃酸和香兰素进行了分析，以硅胶GF254作为吸附剂，从几种溶剂系统中选出氯仿：乙酸乙酯：正丙醇：冰乙酸：水＝20：1：1：1：2溶液作为展开剂。建立了 香兰素的薄层扫描定量分析方法，测定波长为500nm，参比波长为570nm，线性范围为0．31－6．2μg。     

毛蕊杜鹃挥发油化学成分研究

毛蕊杜鹃(Rhododendron tubulosum Ching ex wang wei-yei)系杜鹃花科杜鹃花属植物,分布于四川、西藏、甘肃和青海,其中青海分布最广,藏民常作为单方草药用于治疗肺炎和老年慢性气管炎,具有镇咳、祛痰作用,本文用自制的同时水汽蒸馏-溶剂萃取装置,从采自青海玉树州的毛蕊杜鹃鲜叶和嫩枝提取挥发油,用毛细管气相色谱-质谱和Kovats指数双重定性法对     

The influence of composition and structure of water-in-oil microemulsions on activities of Iraqi Turnip peroxidase

The activity of the enzyme Iraqi Turnip peroxidase (ITP) is studied in a reverse microemulsion composed of chloroform, aqueous buffer, sodium dodecylsulfate (SDS) and alcohols of the homologous series 1-propanol to 1-hexanol through the measurements of absorbancy of the product of oxidation at the wavelength of 470 nm in the course of reactions. The ITP catalyzed reaction is the oxidation of guaiacol by hydrogen peroxide. Maximum enzyme activity was obtained at ω₀ (molar ratio of water to surfactant) = 8. It was found that the oxidation reaction obeyed Michaelis–Menten kinetics in the investigated concentration rang (0.08–0.8 mM) of the substrate, and the Michaelis constant K_m and maximal reaction rate V_m were determined. The enzyme inhibition caused by the alcohols in microemulsions is a consequence of both the solubility of the alcohols in the buffer and the flexibility of the interfacial film.     

复合氧化物负载的Ni基催化剂上愈创木酚加氢脱氧性能

分别以Al₂O₃-SiO₂,Al₂O₃-TiO₂,TiO₂-SiO₂和TiO₂-ZrO₂双金属氧化物为载体研究Ni基催化剂的愈创木酚加氢脱氧性能. 重点考察了催化剂载体、溶剂种类、反应温度和压力对愈创木酚转化率及产物选择性的影响,并对催化剂的抗积碳性能、重复利用性能和愈创木酚加氢脱氧反应机理进行了探讨. 通过BET（Brunauer-Emmett-Teller）比表面积、X射线衍射（XRD）、NH₃程序升温脱附（NH₃-TPD）和H₂程序升温还原（H₂-TPR）等表征手段对催化剂的比表面积、物相结构、表面酸性、可还原性能进行了表征. 结果表明,Ni/TiO₂-ZrO₂催化性能相对较优. 在300 ℃、初始氢压4 MPa、以十氢萘为溶剂的最佳反应条件下,愈创木酚的转化率为100%,环己烷选择性高达86.4%. 该催化剂还具有抗积碳性能,反应后的催化剂上仅检测到3.2%（质量分数）的积碳量.     

TS-1/H2O2碱溶液中低温氧化愈创木酚制备马来酸（英）

可再生生物质资源的开发与利用能够缓解化石燃料产生的温室气体对环境的负面影响.在生物质燃料制备过程中联产高附加值化学品能大幅提高生物质炼制的经济性.愈创木酚是常见的木质纤维素快速热解产物.本文研究了低温液相氧化愈创木酚制备马来酸,并重点考察了催化剂添加量、pH值、反应时间和反应温度等反应条件的影响.研究发现,在钛硅沸石-过氧化氢碱溶液氧化反应体系中（80℃,pH=13.3）,20₃0mol%的愈创木酚可以选择性转化为马来酸.同时初步探讨了愈创木酚氧化开环转化为马来酸的反应机理.     

Guaiacol as an Organic Superoxide Dismutase Mimics for Anti-ageing a Ru-based Li-rich Layered Oxide Cathode

High-capacity Li-rich layered oxides using oxygen redox as well as transition metal redox suffer from its structural instability due to lattice oxygen escaped from its structure during oxygen redox and the following electrolyte decomposition by the reactive oxygen species. Herein, we rescued a Li-rich layered oxide based on 4d transition metal by employing an organic superoxide dismutase mimics as a homogeneous electrolyte additive. Guaiacol scavenged superoxide radicals via dismutation or disproportionation to convert two superoxide molecules to peroxide and dioxygen after absorbing lithium superoxide on its partially negative oxygen of methoxy and hydroxyl groups. Additionally, guaiacol was decomposed to form a thin and stable cathode-electrolyte interphase (CEI) layer, endowing the cathode with the interfacial stability.     

Selective Curcuminoid Separation and Detection via Nickel Complexation and Adsorptive Stripping Voltammetry

Curcumin is a widely studied biologically active redox molecule. Although sensitive, electrochemical methods are commonly hindered by their lack of specificity. This article demonstrates how curcumin may be readily separated from other structurally and electrochemically similar redox moieties. This separation is achieved through exploitation of the molecules diketone functionality providing a route for its selective chelation to nickel(II). Recovery of the curcumin from the nickel complex is achieved simply and quantitatively through acidification of the precipitate. Adsorptive stripping voltammetry at a carbon screen‐printed electrode (SPE) is utilised both as a method for evidencing the effectiveness of the separation technique but further as a procedure for the analytical quantification of the curcumin concentration.     

Ab Initio Studies on the Molecular Conformation of Lignin Model Compounds I. Conformational Preferences of the Phenolic Hydroxyl and Methoxy Groups in Guaiacol

Summary. The conformational preferences of the lignin guaiacyl structural unit were studied at the MP2/6-311G(d,p) level of theory using guaiacol (2-methoxyphenol) as model compound. The potential energy surface of guaiacol was investigated by the ab initio method with full geometry optimization by varying the torsion angles of the guaiacol functional groups (hydroxyl and methoxy). An overall of nine stationary points were located, four of which were found to be minima and the other five transition structures between them. The energy minima of guaiacol can adopt one cisoid and three transoid conformations for the hydroxyl and methoxy groups. The transoid structures differ by the orientation of the methoxy group inside and outside of the aromatic plane. The most stable cisoid conformer has an intramolecular hydrogen bond between phenolic hydrogen and methoxy oxygen with a binding energy of 18.09–18.51 kJ/mol as calculated with the second-order (MP2) and fourth-order (MP4SDQ) M?ller-Plesset methods and with larger polarized basis sets including diffuse functions. When comparing the geometrical parameters of the global energy structure with relevant experimental data from crystallographic structures good agreement between the data was found. The saddle points, the effect of calculation level on the energy relative stability, the rotational barrier heights, and the relative concentrations of the conformers are also discussed.