内噪声作用下的随机共振算法对弱信号的检测

基于随机共振理论提出了一种简便、有效地检测弱信号的方法。在内噪声协同作用下，通过调节输入噪声信号的大小能较好地提高系统输出信号的信噪比，从而实现检测背景噪声很强的弱信号的目的。应用于模拟信号和实验信号的结果证明了方法是可行的。     

Weighted two-band target entropy minimization for the reconstruction of pure component mass spectra: Simulation studies and the application to real systems

A method is proposed, on the basis of a recently developed algorithm--Band Target Entropy Minimization (BTEM)--to reconstruct mass spectra of pure components from mixture spectra. This method is particular useful in dealing with spectral data with discrete features (like mass spectra). Compared to the original BTEM, which has been applied to differentiable spectroscopies such as Fourier-transfer infrared spectroscopy (FTIR), ultraviolet (UV), Raman, and nuclear magnetic resonance (NMR), the latest modifications were obtained through: (1) Reformulating the objective function using the peak heights instead of their derivatives; (2) weighting the abstract vector VT to reduce the effect of noise; (3) using a two-peak targeting strategy (tBTEM) to deal with strongly overlapping peaks; and (4) using exhaustive search to locate all the component spectra. A set of 50 multi-component mass spectra was generated from ten reference experimental pure component spectra. Many of the compounds chosen have common MS fragments and therefore, many of the pure component spectra have considerable intensity in same data channels. In addition, a set of MS spectra from a real system with four components was used to examine the newly developed algorithm. Successful reconstruction of the ten component spectra of the simulated system and the four component spectra of the real system was rapidly achieved using the new tBTEM algorithm. The advantages of the new algorithm and its implication for rapid system identification of unknown mixtures are readily apparent.     

La—Ba—Na—O催化剂上甲烷氧化偶联宏观反应动力学研究

甲烷氧化偶联反应在不同催化剂体系上动力学的研究各不相同,我们已报道了La-Ba-O系复合氧化物催化剂对此反应的优良催化性能。本文则是对该催化剂上的甲烷氧化偶联反应的动力学进行初步探讨。     

堇青石窑具多晶结构与性能研究

利用X-射线衍射分析和电子显微镜分析的结果，确定堇青石窑具的多晶结构和各晶相的含量；结合窑具性能的研究，确定堇青石窑具具有优良性能的适宜配方。     

SO_4~（2－）／Fe_2O_3－Dy_2O_3催化α－萘乙酸与甲醇酯化反应的色谱法研究

ＳＯ２－４／Ｆｅ２Ｏ３－Ｄｙ２Ｏ３是一种新的稀土改性固体超强酸，研究结果表明它对α－萘乙酸与甲醇酯化反应有很高的催化活性和良好的稳定性。反应混合物在ＮｏｖａｐａｋＣ１８（３．９×１５０ｍｍ，４μ）色谱柱上以甲醇－水（７０∶３０，Ｖ／Ｖ）作流动相８分钟内可实现良好分离。该反应产率高、工艺简便、无腐蚀。     

反相高效液相色谱法测定Arthrobacter sp.黄嘌呤氧化酶活性

报道了采用反相高效液相色谱法(RP-HPLC)测定节杆菌(Arthrobacter sp.)黄嘌呤氧化酶活性的有效方法. 将酶初提液与含有黄嘌呤的反应体系在37 ℃下反应20 min, 反应终止后通过HPLC测定产物尿酸生成量的变化来分析酶的活性. 通过流动相组成、pH和柱温等分离条件的优化, 确定了最佳的色谱检测条件以NH4H2PO4 (50 mmol/L, pH 7.5)溶液为流动相, 流速1 mL/min, 柱温25 ℃, 检测波长290 nm. 为深入研究微生物细胞内黄嘌呤氧化酶提供了高效检测手段.     

LaCo13基金属间化合物的磁性能和储氢性能

对LaCo13基金属间化合物在磁致冷材料和储氢材料领域中的应用进行了综述,总结了该系化合物的成相规律、替换元素对相稳定性的影响,讨论了近期的研究进展及存在的问题。作为磁致冷材料应用时,LaCo13基金属间化合物在室温具有巨大磁熵变,而作为储氢合金时该系化合物表现出优异的高温电化学容量。虽然在磁致冷和储氢材料领域尚未对LaCo13基金属间化合物进行实用开发,但作为新型绿色能源材料已经展示出良好的应用前景。     

Nonisothermal Kinetics of Sub‐Solidus Phase Transitions in C10Zn,C16Zn and Their Binary System

Nonisothermal kinetics of the solid‐solid phase transition in (n‐C₁₀H₂₁NH₃)₂ZnCl₄(C₁₀Zn), (n‐C₁₆H₃₃NH₃)₂ZnCl₄(C₁₆Zn) and their binary system were determined by Kissinger and Ozawa methods from DSC measurements. The activation energy E_a of the binary system shows a waving dependence on W_C10Zn%, which is caused by not only an intermediate (C₁₀H₂₁NH₃)(n‐C₁₆H₃₃NH₃)ZnCl₄ but also three solid solution ranges (α, β, γ) in the phase diagram of C₁₀Zn‐C₁₆Zn. The variations of the layer d‐spacing are also convenient for the above result.     

Chemical Constituents of Ailanthus triphysa

Two new compounds,8(14),15-isopimaradiene-2α，３α，19-triol(1),and 6α，７β－dihydroxy-17(20)-cis-5α－pregna-16-one(2),together with four known copounds,a oxygenated rare phyllocladane,phyllocladan-16α，19-diol(3),kaempferol-3-0-β－Ｄ-galactopyranosied,kaempferol-3-0-α－Ｌ－rhamnopyranoside and scopoletin, were isolated from the leaves of Ailanthus tripysa.Structures of 1-3 were elucidated on the basis of spectroscopic data as compared with related compounds.     

In Situ IR Spectroscopic Studies on Molybdenum Nitride Catalysts: Active Sites and Surface Reactions

Recent IR spectroscopic studies on the surface properties of fresh Mo₂N/-Al₂O₃ catalyst are presented in this paper. The surface sites of fresh Mo₂N/-Al₂O₃, both Mo⁺ (0<<2) and N sites, are probed by CO adsorption. Two characteristic IR bands were observed at 2045 and 2200 cm^-1, due to linearly adsorbed CO on Mo and N sites, respectively. The surface N sites are highly reactive and can react with adsorbed CO to form NCO species. Unlike adsorbed CO on reduced passivated one, the adsorbed CO on fresh Mo₂N/-Al₂O₃ behaves similarly to that of group VIII metals, suggesting that fresh nitride resembles noble metals. It is found that the surface of Mo nitrides slowly transformed into sulfide under hydrotreating conditions, which could be the main reason for the activity drop of molybdenum nitride catalysts in the presence of sulfur-containing species. Some surface reactions, such as selective hydrogenation of 1,3-butadiene, isomerization of 1-butene, and hydrodesulfurization of thiophene, were studied on both fresh and reduced passivated Mo₂N/-Al₂O₃ catalysts using IR spectroscopy. The mechanisms of these reactions are proposed. The adsorption and reaction behaviors of these molecules on fresh molybdenum nitride also resemble those on noble metals, manifesting the unique properties of fresh molybdenum nitride catalysts. Mo and N sites are found to play different roles in the adsorption and catalytic reactions on the fresh Mo₂N/-Al₂O₃ catalyst. Generally, Mo sites are the main active sites for the adsorption and reactions of adsorbates; N sites are not directly involved in catalytic reactions but they modify the electronic properties of Mo sites.