差分吸收光谱法测量大气污染的测量误差分析

差分吸收光谱技术被广泛地应用于测量大气中微量元素的浓度，尽管该技术利用最小二乘法来反演待测气体的浓度，能够得到很高的测量精度。但是，由于仪器本身的噪声以及测量波段其它气体的干扰等，使得仪器的测量有一定的误差，而且上述因素还决定着仪器的测量下限。对差分吸收光谱方法的测量误差以及引起误差的原因作了详细的分析。     

Pointwise Estimates for a Class of Oscillatory Integrals and Related Lp–Lq Estimates

In this article we establish pointwise estimates for a class of oscillatory integrals related to the fundamental solution of the dispersive equation ∂_t u − iP (D_x)u = 0, where P(D_x) is a differential operator whose symbol P(ξ) is a real polynomial in one variable. Then we use such pointwise estimates to establish L^p–L^q estimates for the solution of this equation.     

物理实验考核初探

在以素质教育为目标的今天，各类学校对实验的认识越来越重视，一般都建立了专门的物理实验室和配备专职的实验员．但对物理实验教学的效果学生实验能力的考查却不够重视．如，考核没有新的实验内容，仍停留在让学生死记一些实验现象或步骤，或者重复做某个实验操作等．随着物理教学改革的深入，物理实验的考核问题必须给予充分的重视，下面对实验考核中的几个问题作初步的探讨．     

Generation of UV laser light by stimulated Raman scattering in D2, D2/Ar and D2/He using a pulsed Nd:YAG laser at 355nm

A pulsed Nd:YAG laser at 355nm is used to pump Raman cell filled with D_2, D_2/Ar and D_2/He. With adequately adjusted parameters, the maximum photon conversion efficiency of the first-order Stokes light (S_1, 396.796nm) reaches 33.33% in D_2/Ar and the stability of S_1 in pure D_2 is fairly high, the energy drift being less than 10% when the pump energy drifts in the range of 5%. The conversion efficiency and stability, which are functions of the composition and pressure of the Raman medium and the energy of pump laser, are investigated. The result has been used to optimize the laser transmitter system for a differential absorption lidar system to measure NO_2 concentration profiles.     

Mid-infrared generation based on a periodically poled LiNbO3 optical parametric oscillator

We report a nanosecond Nd:YVO_4-pumped optical parametric oscillator (OPO) based on periodically poled LiNbO_3 (PPLN). Tuning is achieved in this experiment by varying the temperature and period of the PPLN. The design of double-pass singly resonant oscillator (DSRO) and confocal cavity enables the OPO threshold to be lowered considerably, resulting in a simple, compact, all-solid-state configuration with the mid-infrared idler powers of up to 466mW at 3.41μm.     

The effect of micro-morphology of Bi2O3 on catalytic properties of Co/Bi catalyst for wet air oxidation of acetic acid

The novel phase transfer catalysts S-8 [4-(dimethyloctylammonium) propansultan] and DB-X [1,4-bis(triethylmethylammonium)benzene dibromide] were synthesized and employed for high conversion synthesis of dichlorocyclopropane from various olefins.This revised version was published online in December 2005 with corrections to the Cover Date.     

The algebraic Bethe ansatz for the Izergin–Korepin model with open boundary conditions

We present the procedure of exactly solving the Izergin–Korepin model with open boundary conditions by using the algebraic Bethe ansatz, which include constructing the multi-particle state and achieving the eigenvalue of the transfer matrix and corresponding Bethe equations. We give a proof about our conclusions on the multi-particle state based on an assumption. When the model is U_q(su(2)) quantum invariant, our results agree with that obtained by analytic Bethe ansatz method.     

Lithium heptadecafluorooctanesulfonate catalyzed Mannich-type and aza-Diels-Alder reactions in supercritical carbon dioxide

The Mannich-type reaction of imines with (1-methoxy-2-methylpropenyloxy)trimethylsilane and aza-Diels-Alder reaction of imines with Danishefsky's diene can be carried out in scCO₂ in the presence of lithium heptadecafluorooctanesulfonate which offer a way to synthesize β-amino carbonyl compounds and nitrogen-containing six-membered ring compounds under environmentally benign conditions.     

Facilitated sulfate transfer across the nitrobenzene-water interface as mediated by hydrogen-bonding ionophores.

Facilitated SO4(2-) transfers by hydrogen bond-forming ionophores are investigated across the nitrobenzene (NB)-water interface by using polarography with a dropping electrolyte electrode. Bis-thiourea 1, alpha,alpha'-bis(N'-p-nitrophenylthioureylene)-m-xylene, is found to significantly facilitate the transfer of the highly hydrophilic SO4(2-) whereas its counterpart, N-(p-nitrophenyl)-N'-propylthiourea (ionophore 2), cannot. In contrast to the predominant formation of a 1:1 complex with SO4(2-) in the bulk NB phase, the SO4(2-) transfer assisted by 1 is indeed based on the formation of a 1:2 complex between SO4(2-) and ionophore, even under the condition of [SO4(2-)]aq > [1]org. Such an exclusive formation of the 1:2 (SO4(2-) to ionophore) complex at the NB-water interface is not observed with structurally similar bis-thiourea 3, alpha,alpha'-bis(N'-phenylthioureylene)-m-xylene, where p-nitrophenyl moietes of bis-thiourea 1 are simply replaced by phenyl groups. The facilitated transfer of SO4(2-) with bis-thiourea 1 is further compared to that of HPO4(2-) and H2PO4- across the NB-water interface, which was previously shown to be assisted by 1 through the formation of the 1:1 and 2:1 (anion to ionophore) complexes, respectively. On the basis of these examinations, unique binding behaviors of hydrogen bond-forming ionophores at the NB-water interface are discussed, with a view towards development of ionophore-based anion-selective chemical sensors.     

Study on the Superhydrophilicity of the SiO2-TiO2 Thin Films Prepared by Sol-Gel Method at Room Temperature

Nanoscale SiO₂-TiO₂ composite thin films with the thickness of about 100 nm were prepared by sol-gel method at room temperature in air. The chemical states of the elements on the surface and near the surface were measured by XPS. The results showed that the Ti on/near the surface of the thin films existed not only as TiO₂ but also as Ti₂O₃. Part of the TiO₂ was changed to Ti₂O₃ after UV irradiation. The crystalline structure of the TiO₂ in the SiO₂-TiO₂ thin films was anatase with the crystallite size of 14–20 nm. It was found that the thin film prepared at room temperature in air has good superhydrophilic property and has strong adherence to the substrate.