毛细管区带电泳测定纳米粒子粒度分布的研究

建立了一种用毛细管区带电泳测定纳米粒子平均粒径及粒径分布的新方法。该方法通过外标定量法对样品的原始电泳谱图进行定量校正,从而得到样品的粒径分布图及平均粒径。外标定量法包括迁移时间-粒径校正曲线的建立及不同粒径含量校正曲线的建立。该方法所需样品量少,且粒度分布结果具有统计代表性。     

Influence of diffusion on pore size distributions determined by xenon porometry

Xenon porometry is a new method for characterization of porous materials. In this method, the material is immersed in a medium, and its properties are studied by means of 129Xe NMR spectra of xenon dissolved in the sample. The method is particularly suitable for the determination of pore size distribution of the material, since the spectra display two signals whose chemical shift is dependent on the pore size. A prerequisite for an accurate determination is the fact that the diffusion of xenon between different pores is slow enough. The diffusion is studied in this work using two-dimensional exchange spectroscopy (2-D EXSY). The spectra measured as a function of the mixing time imply that the exchange is really slow as compared with the NMR time scale, and therefore the distribution of the resonance frequencies indeed represents the pore size distribution.     

A comparison of liquid–liquid porosimetry equations for evaluation of pore size distribution

This paper reviews and numerically tests many of the methods for the determination of pore size distribution of liquid membranes by liquid–liquid porosimetry. The flux through membranes was defined for flow of two immiscible liquids when drops or a liquid jet is formed, as well as the case when the interface is forced out by sufficient pressure. Several methods from literature for the determination of pore size distribution, some variations of these, and one new method are presented with a consistent theoretical basis. Using numerical tests it was found that all methods were very sensitive to measurement noise as low as ±0.1%, and that some form of data smoothing, such as a smoothing spline, was required to obtain a satisfactory distribution. The effects of elastic and permanent membrane compression were tested and a method was proposed to reduce the resulting error. A method based on the ratio of flux liquids with and without a liquid–liquid interface was recommended as it was less sensitive to the effects of compression in some cases and it provides a check when compression is not repeatable.     

Determination of spherulite size distribution by small-angle light scattering

The theoretical backgrounds of the method of spherulite size distribution determination, on the basis of the small-angle light scattering technique, are presented. Special corrections of experimental data are introduced to achieve great accuracy of the determination of scattered light intensity distribution. Experiments have been done on low-density polyethylene samples obtained in various crystallization conditions. For these samples, the stepwise distributions of spherulite size have been determined.     

Some aspects of determination of radionuclides at the former Semipalatinsk Nuclear Test Site

There is investigated a radionuclide composition of the soil samples, selected in various parts of former Semipalatinsk Nuclear Test Site (SNTS). The gamma-spectrometric method was used for determination of¹³⁷Cs and²⁴¹Am. For determination of⁹⁰Sr and isotopes of plutonium a radiochemical separation was used. The results of determinations show a distinction in distribution of radionuclides on depth for various investigated areas and for various size fractions of surface layers. The study of the size fractions has shown an enrichment of a magnetic faction by²⁴¹Am.     

Morphological analysis of polymer systems with broad particle size distribution

This contribution is focused on precise determination of particle size distribution in polymer blends with complex morphology by means of our new program called MDISTR. Standard determination of the particle size distribution is usually achieved by measurement of particle sizes in (a single set of) electron micrographs. We show why this method fails for two frequent cases: (i) blends with very broad particle size distribution and (ii) blends that are composed of domains with different particle sizes. On real-life examples, we demonstrate that program MDISTR yields accurate particle size distributions in both the above-mentioned cases, while the standard image analysis gives average particle sizes differing by >100 % from the correct result. We describe MDISTR calculations which are based on a linear combination of standard particle size distributions from two (or more) sets of micrographs with different magnifications, different locations within the sample and precisely defined statistical weights.     

基于单颗粒电感耦合等离子体质谱法测定环境基质水样中纳米银颗粒

采用单颗粒电感耦合等离子体质谱法(SP-ICP-MS)同时测定环境水样中纳米银颗粒(AgNPs)的颗粒浓度、质量浓度和粒径分布,并考察了溶液的pH值、溶解性有机质(DOM)浓度以及离子强度等对AgNPs测定的影响。结果表明:SP-ICP-MS方法对60 nm AgNPs标准溶液的测定结果与标准值一致,准确性较好;pH值(5.0～7.0)、离子强度(≤1 mmol/L)和DOM浓度(≤30 mg/L)对测定结果影响较小;当溶液的pH值≤5.0或离子强度1 mmol/L时,AgNPs的颗粒浓度和粒径随pH值的下降或离子强度的增强而减小。采用SP-ICP-MS方法测定河水、染料废水、养殖废水3种水样中AgNPs的加标回收率分别为98.1%、83.3%和93.3%,表明该方法在合适的基质条件下可用于快速准确测定环境水样中AgNPs的颗粒浓度、质量浓度和粒径分布。     

金纳米粒子的微波法合成及在蛋白质检测中的应用

通过对微波反应器中氯金酸和柠檬酸钠混合物进行直接加热,快速、一步合成了金纳米粒子.通过调节反应初始混合物中氯金酸与柠檬酸钠的比例,可获得不同粒径窄分散的金纳米粒子.进一步将所合成的金纳米粒子功能化,考察了其在蛋白质检测中的应用.     

An Image-Based Technique for Measuring Droplet Size Distribution: The Use of CNN Algorithm

A challenging task in measuring droplet size is the ability to perform in-situ droplet size distribution analysis on multiphase fluids in their native states in the undisturbed environment. In this study, an inline two-dimensional low cost–high accuracy technique is presented for continuous measurement of spherical or non-spherical droplets in emulsions using image processing. The characteristic of the droplets is evaluated and the describe drop size distributions in different ranges is determined. This droplet size determination algorithm is based on both cellular neural networks and linear matrix inequality. Our main work focuses on the performance of the proposed methodology for exploring the dynamical evolution of such droplet size distributions by in-situ measurement. Moreover, the results were compared with those obtained using laser diffraction analyzer technique. It was proved that this method can efficiently characterize the quality of dispersed phase by determining droplet size distribution.     

Characterization of nanoparticles

Nanoparticles with diameters from 1–100 nm are used in large quantities for very different applications. A precise determination of the important physical quantities (which are responsible for the application properties) such as diameter, particle size distribution, and surface is therefore very essential. The most common methods for the determination of these quantities are analytical ultracentrifugation (AUC) and dynamic light scattering (DLS). The paper demonstrates the techniques of getting a precise characterization of nanoparticles and suggests a new method for the correction of the sedimentation coefficient and its distribution with respect to the diffusion coefficient.     

Distribution of carbon nanotube sizes from adsorption measurements and computer simulation

The method for the evaluation of the distribution of carbon nanotube sizes from the static adsorption measurements and computer simulation of nitrogen at 77 K is developed. We obtain the condensation/evaporation pressure as a function of pore size of a cylindrical carbon tube using Gauge Cell Monte Carlo Simulation (Gauge Cell MC). To obtain the analytical form of the relationships mentioned above we use Derjaguin-Broekhoff-deBoer theory. Finally, the pore size distribution (PSD) of the single-walled carbon nanohorns (SWNHs) is determined from a single nitrogen adsorption isotherm measured at 77 K. We neglect the conical part of an isolated SWNH tube and assume a structureless wall of a carbon nanotube. We find that the distribution of SWNH sizes is broad (internal pore radii varied in the range 1.0-3.6 nm with the maximum at 1.3 nm). Our method can be used for the determination of the pore size distribution of the other tubular carbon materials, like, for example, multiwalled or double-walled carbon nanotubes. Besides the applicable aspect of the current work the deep insight into the problem of capillary condensation/evaporation in confined carbon cylindrical geometry is presented. As a result, the critical pore radius in structureless single-walled carbon tubes is determined as being equal to three nitrogen collision diameters. Below that size the adsorption-desorption isotherm is reversible (i.e., supercritical in nature). We show that the classical static adsorption measurements combined with the proper modeling of the capillary condensation/evaporation phenomena is a powerful method that can be applied for the determination of the distribution of nanotube sizes.     

Application of a Laser Diffraction Method for Determination of Stability of Dispersion Systems in Food and Chemical Industry

Laser diffraction was used for determination of particle size of various emulsions. Mean particle size, fractions' number, and dispersion coefficients of tested systems are presented. Stability of greasing emulsions in relation to their pH was also tested. It was found out that determination of droplet size distribution in fat emulsions allows prediction of their properties (stability). The parameter may be helpful in selection of appropriate production process parameters, composition, and control of marketed emulsion systems during their storage. The purpose of the study was to determine applicability of a laser diffraction method for evaluation of stability of selected dispersion systems in food and chemical industry.     

Correction to Microscopically Determined Particle Size According to Diffraction Correction Theory: II. Application to Aqueous Polystyrene Latex Particles of Varying Size

The theory of diffraction correction for transparent (phase) spherical particles under partially coherent illumination has been applied to the optical photomicrographic determination of particle size distribution for four different nearly monodisperse polystyrene latex samples. The thus corrected particle size distribution for each sample has been compared with the corresponding electron microscopic determination.     

Sample size determination for within‐device precision

The within‐device precision for quantitative assays is the square root of the total variance, which is defined as the sum of the between‐day, between‐run, and within‐run variances under a two‐stage nested random‐effects model. Currently, methods for point and interval estimations have been proposed. However, the literature on sample size determination for within‐device precision is scarce. We propose an approach for the determination of sample size for within‐device precision. Our approach is based on the probability for which the 100(1 − α)% upper confidence bound for the within‐device precision smaller than the pre‐specified claim is greater than 1 − β. We derive the asymptotic distribution of the confidence upper bound based on the modified large‐sample method for sample size determination and allocation. Our study reveals that the dominant term for sample size determination is the between‐day variance. Results of simulation studies are reported. An example with real data is used to illustrate the proposed method. Copyright © 2014 John Wiley & Sons, Ltd.     

毛细管区带电泳法测定超细β分子筛的平均粒径及粒径分布

建立了毛细管区带电泳(CZE)测定超细β分子筛平均粒径及粒径分布的测定方法。通过研究β分子筛的等电点,确定了CZE法测定过程中β分子筛悬浮液分散稳定的方法。以激光粒度仪粒径分布测量数据为基准,结合β分子筛电泳谱图,建立了β分子筛粒径-迁移时间校正方程及含量校正方程。样品用量小、分析成本低、测试速度快是该方法的主要特点。     

Correction to Microscopically Determined Particle Size According to Diffraction Correction Theory

The theory of diffraction correction for transparent (phase) spherical particles under partially coherent illumination has been applied to the optical photomicrographic determination of particle size distribution for four different nearly monodisperse polystyrene latex samples. The thus corrected particle size distribution for each sample has been compared with the corresponding electron microscopic determination. Copyright 1999 Academic Press.     

Ellipsometric determination of the structure of nanoscale porous layers

A new ellipsometric method is proposed to measure adsorption in thin layers directly in a stream of vapors of volatile liquid and inert gas at atmospheric pressure. The method enables the determination of the main structural parameters of nano- and microporous materials: the average pore size, pore surface, size pore distribution, and the total porosity of sorbents. A procedure to find the Young modulus in nanoscale porous layers with the use of a spectroellipsometer is described.     

Average cluster size determination in supersonic beams from angular distribution measurements after scattering by a buffer gas

A method for the determination of average cluster size in supersonic beams is presented. Based on angular distribution broadening of the beams caused by passing through a buffer gas, this method is well suited for in situ determination of the mean cluster size when the apparatus contains a movable detector with sufficient spatial resolution. The shape and width of the beam profile after scattering by a buffer gas are evaluated theoretically as functions of buffer gas pressure and atom-cluster collision cross-section. Experimental results are presented for an argon beam, yielding average cluster sizes between 300 and 7000 atoms depending on the stagnation pressure. Simple criteria to assess the applicability of the method to a given experimental situation are discussed. The average cluster sizes determined in this work agree quite satisfactorily with previously published values for similar beam generation conditions.     

Size‐exclusion chromatography for the determination of the boiling point distribution of high‐boiling petroleum fractions

The paper describes a new procedure for the determination of boiling point distribution of high‐boiling petroleum fractions using size‐exclusion chromatography with refractive index detection. Thus far, the determination of boiling range distribution by chromatography has been accomplished using simulated distillation with gas chromatography with flame ionization detection. This study revealed that in spite of substantial differences in the separation mechanism and the detection mode, the size‐exclusion chromatography technique yields similar results for the determination of boiling point distribution compared with simulated distillation and novel empty column gas chromatography. The developed procedure using size‐exclusion chromatography has a substantial applicability, especially for the determination of exact final boiling point values for high‐boiling mixtures, for which a standard high‐temperature simulated distillation would have to be used. In this case, the precision of final boiling point determination is low due to the high final temperatures of the gas chromatograph oven and an insufficient thermal stability of both the gas chromatography stationary phase and the sample. Additionally, the use of high‐performance liquid chromatography detectors more sensitive than refractive index detection allows a lower detection limit for high‐molar‐mass aromatic compounds, and thus increases the sensitivity of final boiling point determination.     

杀虫单介稳区宽度的理论计算

从晶体生长成核、动力学等几个方面出发,在Mersmann模型基础上建立了适合高粘度有机体系的介稳区宽度的理论计算模型,确立了计算程序和方法.结合“杀虫单”农药结晶过程的具体参数,计算和预测了工业结晶过程中介稳区的宽度.理论计算值与实验测定值较为接近.该方法可为工业结晶中过饱和度的选择提供参考.