一种高信噪比的双光束激光光声光谱仪原理及应用

作为一种新兴的检测手段 ,激光光声光谱技术与其他检测技术相比具有很多优点。本文设计的光声光谱仪用激光做光源 ,有两个光声池 ,分别用来放置参考样品和待测样品 ,输出结果为二者光声信号的比值。利用这一比值 ,可以由参考样品的性能参数方便地求出待测样品的相关性能参数。该光声光谱仪有效地减小了本底吸收噪声的影响 ,提高了信噪比 ,扩大了固体光声理论的应用范围。本文还阐述了该光声光谱仪在定性定量分析中的一些应用     

Point load determination of static elastic moduli using laser speckle interferometry

Electronic speckle interferometry (ESPI) is used to determine the Young's modulus E and Poisson ratio ν of an isotropic material. Micron scale deformations of the surface of the block of polymethyl-methacrylate (PMMA) are induced by normal application of a known near-point force. These deformations are recorded in speckle interferometric fringe patterns. An iterative minimum error inversion technique is developed to obtain the elastic properties from the positions of fringe peaks and troughs observed in the fringe patterns. Sensitivity tests of the method on calculated fringe patterns using measured experimental uncertainties suggest the technique will provide measures of the elastic moduli to better than 5%. In an experimental test on a bloc of PMMA (acrylic) the technique gave values of E and ν that differed from corresponding measures obtained using more conventional strain-gauge methods by less than 4%.     

Synthesis,Structure and Photoluminescence of Co-crystal of Bis[2-(benz(oxa/imida)zol-2-yl)phenolato-κ2N,O]zinc(Ⅱ) Being Site Occupancy Disorder with a Heteroatom Ratio of NH to O (0.408/0.592)

The zinc(Ⅱ) complex with Hpbx (Hpbx = 2-(benzoxazol-2-yl)phenol) and Hpbm (Hpbm=2-(benzimidazol-2-yl)phenol),namely[Zn(pbm)2]1.633[Zn(bpx)2]2.367·DMF·2H2O1,has been synthesized and characterized by X-ray crystallography,FTIR and elemental analysis.The coordination structures are statistically disordered and can be regarded as a co-crystal of [Zn(pbm)2]and [Zn(pbx)2] with the ratio of ca.0.408/0.592.Solvate water and DMF molecules are also present in the lattice.Crystal data for 1:monoclinic,space group P21/c,Mr= 2049.02,Z = 2,α = 9,7571(6),b = 25.6415(16),c = 19.8675(10)(A),β = 111.342(2)°,V = 4629.7(5) (A)3,Dc = 1.470 g/cm3,μ =1.100 mm-1,F(000) = 2104,R = 0.0575 and wR = 0.1282 for 5528 observed reflections (I＞ 2σ(I)).The photoluminescent spectra for this compound have also been studied.     

比值光谱导数法同时测定铝合金中铁,铜,锌

用比值光谱－导数分光光度法，在ｐＨ５．５缓冲溶液中，利用金属－２－（５－溴－２－吡啶偶氮）－５－二乙氨基酚（５－Ｂｒ－ＰＡＤＡＰ）－ＯＰ三元络合物显色体系，对混合物中铁，铜，锌三组分进行了同时测定。合成试样５次测定回收率在９７．３％－１０４．４％之间。应用于铝合金中铁，铜，锌的测定，各６次测定的ＲＳＤ分别为３．６６％，１．３８％，２．０３％。     

Resolution of global signals using ratio differential pulse polarograms: Determination of p-nitroaniline and p-nitrotoluene in their mixture

Ratio differential pulse polarograms obtained by dividing the multianalyte and single analyte signals are proposed as a tool for resolution of global signals and quantification of the analytes from a qualitatively known mixture by differential pulse polarography (DPP) and related electroanalytical techniques. The influences of shape and position of the resolving function (DP polarograms of individual analyte) on the efficiency of resolution are discussed on simulated and experimental results. The method is applied for the determination of p-nitroaniline (NA) and p-nitrotoluene (NT) from their mixture in N,N′-dimethylformamide solutions with 0.1 M tetrabutylammonium iodide as supporting electrolyte, using an external calibration diagram and internal standard addition methods. NA and NT give one-electron DP polarographic peaks with 93 mV of peak separation and, therefore, show significant overlapping which depends on the concentration ratio of NA and NT in the mixture. The method is especially suitable for quantification of one analyte in the presence of a large excess of another analyte, because by division the component in excess is removed and the pseudo-ratio DPP of the minor component is clearly revealed in a way which is not possible by deconvolution using polynomial division or deconvolution by Fourier transforms.     

Importance of the choice of assumptions and models in the estimation of analytical quality specifications

The validity of any model depends on its ability to imagine the situation or problem to which it is applied. Further, the assumptions made in relation to the model are determining for the actual outcome. Within the field of clinical biochemistry a lot of models for analytical quality specifications, based on a variety of concepts and ’clinical settings’, have been proposed. A hierarchical structure for application of these approaches and models has been agreed on at several occasions in 1999. In this hierarchy, the highest rank is given to evaluation of analytical quality specifications based on ’clinical settings’/’clinical outcome’ models, followed by specifications based on biological variation and on ’clinicians opinions’. This contribution, deals with the problems of combining random and systematic errors and the implications of application of different models to a variety of clinical settings. Received: 1 June, 2002 Accepted: 17 July 2002 Presented at the European Conference on Quality in the Spotlight in Medical Laboratories, 7–9 October 2001, Antwerp, Belgium     

Improved Flexural Strength of N-Vinyl-Pyrrolidone Modified Acrylic Acid Copolymers for Glass-Ionomers

Abstract

The flexural strengths of N-vinylpyrrolidone modified glass-ionomer cements were investigated. The optimal molar ratio of the monomers in copolymers, composed of the three components acrylic acid, itaconic acid and N-vinylpyrrolidone, was determined using a SAS statistical program. The copolymers were prepared using a free-radical polymerization process. The viscosities of aqueous solutions of these polymers were determined. Cements were formed by the reaction of these solutions with glass particles. Flexural strength (FS) was used as the basic screening property to find the optimum molar ratio. Statistical models were applied to predict the optimum molar ratios. All strength values were recorded on the specimens conditioned in distilled water at 37°C for 7 days. The optimal molar ratio for these copolymers was 7:1:3 for poly(acrylic acid-co-itaconic acid-co-N-vinylpyrrolidone), based on flexural strength and viscosity. The effect of molecular weight (MW) on FS was also evaluated. Copolymer with a MW of 10, 800 (M_n) showed 85% higher FS than the Ketac-Molar (KM) system, along with a reasonable working viscosity.     

Effect of purified fractions from cell culture supernate of high‐density pre‐B acute lymphoblastic leukemia cells (ALL3) on the growth of ALL3 cells at low density

The mechanisms underlying the aberrant growth and interactions between cells are not understood very well. The pre‐B acute lymphoblastic leukemia cells directly obtained from an adult patient grow very poorly or do not grow at all at low density (LD), but grow better at high starting cell density (HD). We found that the LD ALL3 cells can be stimulated to grow in the presence of diffusible, soluble factors secreted by ALL3 cells themselves growing at high starting cell density. We then developed a biochemical purification procedure that allowed us to purify the factor(s) with stimulatory activity and analyzed them by nanoliquid chromatography‐tandem mass spectrometry (nanoLC‐MS/MS). Using nanoLC‐MS/MS we have identified several proteins which were further processed using various bioinformatics tools. This resulted in eight protein candidates which might be responsible for the growth activity on non‐growing LD ALL3 cells and their involvement in the stimulatory activity are discussed.     

Preparation of novel chelating sponge as an adsorbent for the removal of Cu~（2＋） from water

The novel chelating sponge modifed with hydroxamic acid groups was prepared by a grafting polymerization followed by a nucleophilic substitution reaction.Elementary analysis,SEM,FT-IR spectroscopy and XPS were used to characterize the spongy adsorbent（PVA-MA-HH）.Adsorption isotherm study indicated that PVA-MA-HH had high equilibrium adsorption capacity for Cu2＋.     

Utilization of Pine Nut Shell derived carbon as an efficient alternate for the sequestration of phthalates from aqueous system

This study highlights the importance of a cheap bio waste; Pine Nut Shell (PNS), from which a carbon is synthesized that can efficiently remove toxic phthalates from an aqueous system. PNS derived carbon shows high affinity toward phthalates in descending order along with adsorption capacity i.e., dibutyl phthalate (DBP) 5.65 mg/g > diallyl phthalate (DAP) 3.64 mg/g > diethyl phthalate (DEP) and 2.87 mg/g > dimethyl phthalate (DMP) 2.48 mg/g. Different characterization techniques such as FTIR, elemental analysis, point of zero electric charge (PZC), SEM, EDX and BET were employed to investigate the binding sites and surface area of the adsorbent. Adsorption experiments were performed both in batch and column modes. Equilibrium studies showed that the Langmuir isotherm fits best to experimental data. Kinetically, adsorption phenomena obeyed pseudo second order. Furthermore, thermodynamic results expressed the exothermic nature of adsorption on the basis of negative value of enthalpy change. Column sorption method was also adapted to check the feasibility of the adsorption process through the investigation of flow rate, breakthrough curve and pre-concentration factor which is found to be 13 for DMP and DEP and 16 for DAP and DBP. Methanol was found to be best solvent for the recovery of phthalates. Application in real water samples also showed good efficiency of PNS derived carbon for the removal of phthalates.