基于液相~(31)P核磁共振的太湖水体溶解态磷富集方法优化研究

铝盐富集法是应用31P核磁共振技术(31P Nuclear magnetic resonance,31P-NMR)分析水体溶解态磷组成的前处理方法。为将该方法更好地应用于太湖水体溶解态磷的研究中,针对铝盐添加时水体的pH值、铝盐的添加量、提取剂的选择、水样体积等进行研究。结果表明,铝盐的添加量不仅和水体中溶解态总磷的浓度有关,也与富集水的体积相关;铝盐添加过程中,水体pH值会影响有机磷的去除率;太湖水体溶解态磷富集的最优方法是取过滤后的湖水20 L,添加3 g AlCl3·6H2O并充分搅拌,且水体pH值保持6.0,静置过夜后,除去上覆水,收集含磷絮状物并离心,最后用0.5 mol/L NaOH+0.1 mol/L EDTA进行提取。     

Response of peptide intensity to concentration in ESI–MS-based proteome

High-throughput quantification with label-free methods has received considerable attention in electrospray ionization(ESI)-mass spectrometry(MS),but the manner by which MS signals respond to peptide concentration remains unclear in proteomics.We developed a new mathematical formula to describe the intrinsic log-log relationship between the MS intensity response and peptide concentration in an analytical ESI process.Experimental results showed that the calibration curve is fairly fit to the log-log formula with a linear dynamic range of approximate four to five orders of magnitude.However,we found that the ionization of analytical peptides can be severely suppressed by coexisting matrix peptides,such that the calibration curve can be poorly leveled off on both ends.Our study suggests that the interferences from coexisting matrix peptides should be reduced in the ESI process to use the log-log calibration curve successfully for the high-throughput quantification.     

On-line capillary electrophoresis enrichment by combining chitosan trapping with surfactant assisted sample stacking for the ultratrace determination of organic acids in Plateau alfalfa roots

In this paper, four organic acids constituents of Plateau alfalfa roots have been identified and detected by a novel capillary electrophoresis (CE) strategy which combined chitosan (CS) trapping and cetyltrimethyl ammonium bromide (CTAB) assisted sample stacking. Under the optimized condition, organic acids, i.e., aconitic acid, gallic acid, citric acid and l-malic acid were concentrated and separated within 3 min. Validation parameters of this method (such as detection limits, linearity and precision) were also investigated and the limit of detection (LOD) was 2.41-53.9 ng mL⁻¹. Linearity was obtained over the magnitude range of 5-4000 ng mL⁻¹ approximately for different organic acids and 3 × 10²-1.5 × 10⁴ folds enrichment was achieved. The method has been applied to the determination of organic acids in roots of normal grown Plateau alfalfa and stressing affected Plateau alfalfa. Satisfactory results and recoveries were obtained in the analysis without costly and complicated sample pretreatment.     

Self-aggregation of liquids from biomass in aqueous solution

Aggregation of several chemicals from biomass: furfural derived compounds (furfural, 5-methylfurfural, furfuryl alcohol and tetrahydrofurfuryl alcohol), lactate derived compounds (methyl lactate, ethyl lactate and butyl lactate), acrylate derived compound (methyl acrylate) and levulinate compounds (methyl levulinate, ethyl levulinate and butyl levulinate) in aqueous solution has been characterised at T = 298.15 K through density, ρ, speed of sound, u, and isentropic compressibilities, κ_S, measurements. In addition the standard Gibbs free energies of aggregation have been also calculated. Furthermore, in order to deepen insight the behaviour of these chemicals in aqueous solution, the solubility of these compounds has been measured at T = 298.15 K.     

Physically nonlinear problems of stress concentration in members,structures, and buildings

Results from studies of stress concentration in physically nonlinear elastic structural members are reviewed __________ Translated from Prikladnaya Mekhanika, Vol. 43, No. 1, pp. 93–99, January 2007.     

Preparation of microspheres by radiation-induced polymerization. II. Mechanism of microsphere growth

The effects of the monomer concentration were investigated on the preparation of diethylene glycol dimethacrylate (2G) microspheres by radiation-induced polymerization. The monomer concentration strongly affected the conversion and the shape of the microspheres. The particles were obtained in the range from 2 to 24 vol % of 2G monomer. The effective concentration for the preparation of monodisperse microspheres is around 10 vol %. Higher monomer concentrations up to 24 vol % gave rough surface particles. Considering the effects on the number of microspheres in the solution, the authors introduced the inhibiting region, where one microsphere disturbs the existence of another microsphere, and tried to explain the mechanism of the microsphere growth. The competition between the propagation and the crosslinking reactions is balanced to give the microspheres.     

用染料激光增益降低二元混合物中少量化合物的受激拉曼散射可探测浓度

在二元混合物构成的圆形谐振腔中,用染料的激光增益增强了少量化合物(乙醇溶液中的甲醇、水溶液中的乙醇)的受激拉曼散射（SRS）光谱,将少量化合物在悬垂液滴中的瞬态SRS探测极限提高了近一个数量级. 用受激拉曼散射理论,解释了增强少量化合物SRS的机理. 关键词： 受激拉曼散射 染料激光增益 二元混合物 最小可探测浓度     

Taking into account physical and instrumental parameters in atomic absorption spectroscopy with a continuous radiation source

We present a detailed analysis of the dependences of the absorption contours and concentration curves on various parameters in atomic absorption spectrometry with a continuous radiation source. We have developed a multifunctional application software package allowing us to calculate the emission and absorption line profiles for different elements under different physical conditions. We take into account Doppler and collisional broadening of the absorption lines, which have a complex structure as a result of the isotopic shift, hyperfine splitting of the components, and also instrumental distortion of these lines. We consider two different procedures for calculating the absorbance and do a comparative analysis of the two procedures. For all the listed cases, we can plot concentration curves and find the absorbance within the classical definition and plot the concentration curve using only a portion of the spectral width of the profile rather than the entire width. We have modeled the instrumental distortions of the spectral profile due to spectral selection, and we have analyzed their effect on the shape of the absorption contour. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 3, pp. 285–289, May–June, 2006.     

Thermo-stress concentration of an orthotropic plate weakened by multiple elliptical holes

A laminate weakened by multiple elliptical holes of arbitrary distribution, arbitrary orientation and arbitrary dimensions, is treated as an anisotropic, infinite, multiple connected thin plate. By Faber series expansion [1–6] and a complex potential method in the plane theory of thermo-elasticity of an anisotropic body, the general step to deduce the thermostress concentration in the laminate subjected to arbitrary mechanical and thermal loads is obtained.Supported by The Chinese Science Foundation of Aeronautics     

四能级和准四能级激活离子的最佳掺杂浓度

推导了在连续抽运和脉冲抽运条件下,利用荧光衰减曲线,在双掺与单掺晶体中,激发态布居数与激活离子掺杂浓度的关系,分析了四能级系统与准四能级系统中激活离子最佳掺杂浓度的计算方法.并利用上述方法,以准四能级系统Tm,Tb:LiYF4和四能级系统Nd:YAG为例,计算了相应离子的最佳掺杂浓度,并与文献的有关报道进行了比较 关键词： 激发态布居数 最佳掺杂浓度 四能级系统与准四能级系统 Tm Tb:LiYF4