Stability of the Dividing Distribution Function Method for ParticleSize Distribution Analysis in Small Angle X－Ray Scattering

The Dividing Distribution Function (DDF) method is one of the methods by which the particle size distribution of ultrafine powder can be evaluated from its small angle X-ray scattering data. In this paper, the stability of the solution obtained from DDF method has been investigated through optimizing the coefficient matrix, introducing a damping factor and a least square treatment. All calculations were accomplished with a microcomputer. It was shown that the average deviations of the size distribution obtained are not larger than the assigned random errors to the scattering intensities as long as the corresponding requirements are satisfied.

Theoretical Study of the Effect of Multi-Diameter Distribution on the Mie Scattering Characteristics of Milk Fat

To correct the light scattering property parameters of milk fat for improving the detection accuracy,the Mie-theory was used to establish a predictive model for light scattering properties of milk fat globule with multi-diameter distributions, by means of Monte Carlo approach to simulate actual multi-diameter size distribution of milk fat globule in milk fat solution. Scattering coefficient and absorption coefficient of multidiameter distribution milk fat particles were calculated by simulating the particles size distribution in milk fat solution. And the light scattering properties of multi-diameter distribution was compared with that of volume mean diameter,Sauter mean diameter and numerical mean diameter in milk fat solution. Theoretical simulation results indicate that the scattering coefficient and absorption coefficient of milk fat particles are determined by the particle size distribution in milk fat solution. There is a distinct difference in scattering characteristics between the milk fat particles with multi-diameter distribution and that with mean diameters. Compared to that with multi-diameter distribution,the scattering coefficient of the milk fat particles with mean diameter has a maximum mean deviation of 9042 m-1. The particle size distribution is not completely determined by the mean diameters. The dependence of the light scattering properties on the particle size distribution should be considered into the model and simulation. Therefore,it is found that the particle size distribution in milk fat solution is an essential and critical factor to significantly improve the detection accuracy of milk fat content.

Whether the Microemulsion is a Nano-pesticide: Exploration from the Perspective of Particle Size and Morphology

[Objectives] The paper was to explore whether the microemulsion is a nano-pesticide. [Methods] Several microemulsions commonly available on the market were studied from the perspective of particle size and morphological characteristics. With ZIF nano-pesticide prepared earlier as the control, the changes in particle size of microemulsions diluted at different concentrations and the microscopic morphology of dispersed particles were tested and compared by dynamic light scattering laser particle size analyzer combined with scanning electron microscope. [Results] Conventional microemulsions were in dynamic equilibrium, and the particle size changed irregularly after dilution at different concentrations. Especially under scanning electron microscope, the particle distribution of pesticide-bearing droplets were uneven after drying, with aggregation and precipitation of large particles, while the particle size of nano-pesticide changed little after dilution at different concentrations, ranging from 1 to 300 nm. Moreover, the microscopic morphology of nano-pesticide observed under scanning electron microscope was in monodisperse nano state, without aggregation. [Conclusions] The particle size measured by dynamic light scattering alone can not judge whether the microemulsion is a nanometer pesticide, and it is necessary to observe the microscopic disperse state and particle size distribution with the help of electron microscopy.

Mastersizer 2000激光粒度分析仪及其应用

概述了Mastersizer 2000激光粒度分析仪的原理与主要性能,在此基础上提出了测量应用中应注意的几个问题,并加以必要的分析。首先测量前最重要的问题是充分地准备样品,包括典型抽样、分散剂、表面活化剂和混合剂选用,超声波的使用等等;其次是要确保测量区的主要组成部件即检测器和样品池窗口一直是清洁的,并利用background测量装置纯化测量;最后被测样品的折光率和吸收率的正确输入也是一个关键因素;做好这些才有望获得重现性好的有效测量结果。

Mastersizer 2000分析报告解析

结合Mastersizer 2000激光粒度分析仪测量实践和实例,对典型的粒度分析报告的栏目内容和参数特征进行了较深入的解析,为激光粒度仪的应用与结果分析提供有益的参考。

Mastersizer 2000型激光粒度仪技术参数对粒度分布的影响

根据英国马尔文Mastersizer 2000型激光粒度仪的特点,探讨不同技术参数对样品粒度分布测试结果的影响。结果表明,影响样品粒度分布的主要参数为样品量(检测遮光度)、采集时间、循环速度、检测光源波长、反演光学模型及数学模型等;对于状态不明确的未知样品,应借助其他检测技术进行样品状态表征后,选择合理的光学模型和数学模型进行粒度测试。

马尔文激光粒度分析仪Mastersizer 2000及其应用

介绍了激光粒度分析仪Mastersizer 2000的工作原理,并以聚丙烯催化剂载体粒径分布测量为例,介绍了Mastersizer 2000的测试方法、参数选择及注意事项,最后对其应用现状进行了综述。

Mastersizer 2000粒径仪对SiO_2粒径分析的影响因素研究

使用英国马尔文公司的Mastersizer 2000激光粒径仪来考察测量条件对Stber法制得SiO2粒径分布结果的影响。通过改变测量过程中的遮光度、泵速、超声波强度等参数,比较不同测量条件对测量结果的影响。实验结果表明,各种测量条件的变化都会对粒径分布结果产生重要影响,在进行测量时应该仔细地选择各项参数。本体系在测量过程中的遮光度不能高于26%,可行的泵速范围是1 500～3 000 r/min,不需要使用超声波帮助分散。

A regularization algorithm for estimating the multimodal size distribution of nanoparticles from multiangle dynamic light scattering

The multiangle dynamic light scattering (MDLS)technique provides more robust,reproducible,and accu- rate particle size distributions (PSDs)than single-angle dynamic light scattering.However,in MDLS,the determination of peak locations is difficult but significant,particularly for multimodal distributions.In this paper,a self-adaptive algorithm,the iterative recursion nonnegative Tikhonov-Phillips-Twomey (IRNNT-PT)algorithm,is proposed for the estimation of the PSD from MDLS measurements.This algorithm optimizes the weighting coefficients,distinguishes features of PSDs and chooses the optimal inversion method from two regularization algorithms self-adaptively.Numerical simulations and experimental results for unimodal and multimodal distributions are presented to demonstrate both the validity and noise immunity of the IRNNT-PT algorithm,and demonstrate that the proposed algorithm can be well applied to reconstruct PSDs from MDLS measurements.

Inversion of particle size distribution from light-scattering data using a modified regularization algorithm

A modified regularization algorithm with a more proper operator was proposed for the inversion of particle size distribution （PSD） from light-scattering data in a laser particle sizer based on the Mie scattering principle. The Generalized Cross-Validation （GCV） method and the L-curve method were used for deter- mining the regularization parameter. The Successive Over-Relaxation （SOR） iterative method was used to increase the exactness and stability of the converged result. The simulated results based on the modified algorithm are in a good agreement with the experimental data measured for nine standard particulate samples, their mixtures as well as three natural particulate materials with irregular shapes, indicating that this modified regularization method is not only feasible but also effective for the simulation of PSD from corresponding light-scattering data.

Determination of deferasirox particle size distribution via laser diffraction and its application in establishing a correlation between particle size and drug dissolution in vitro

Deferasirox is the first-line drug for iron overload due to thalassemia in adults and pediatric patients. It is classified as a type II compound in the Biopharmaceutics Classification System, and thus the particle size of its active pharmaceutical ingredient(API) should be strictly controlled during the manufacturing process. In the present study, laser diffraction was adopted to measure the particle size distribution of deferasirox API. We also developed and validated an accurate and convenient method by investigating important optical parameters and sample dispersing conditions. The relative standard deviation values, namely, d(0.1), d(0.5), d(0.9), and d(4,3), measured via methodology validation and actual sample measurement were < 3%. The dissolution curves of several batches of dispersible tablets prepared using deferasirox with different particle sizes were compared in the four dissolved media to investigate the influence of particle size on drug dissolution in vitro. Results indicated that the particle size distribution of deferasirox API significantly affected the release of its dispersible tablet.

DETERMINATION OF SIZE DISTRIBUTION OF THE CRYSTALLINE PARTICLE IN AGED METALLIC GLASS BY SMALL ANGLE X-RAY SCATTERING

Ⅰ. INTRODUCTIONAlthough many authors have investigated the structure of annealed metallic glass by means of small angle X-ray scattering (SAXS), there has been no report in which size distribution of the crystalline particle in aged metallic glass is determined. Determining size distribution of the crystalline particle will be beneficial to understanding the nucleation and growth process of the crystalline particle. In this note, size distribution of the crystalline parti-

激光粒度仪在特殊土颗粒分析试验中的应用

采用激光粒度仪对膨胀土、黄土和红土进行了颗粒分析试验,研究了取样质量和超声波分散时间对试验结果的影响,发现遮光率与取样质量呈现很好的线性正相关,给出了特殊土在激光粒度仪法试验中适宜的遮光率范围(15%~25%)、取样质量(膨胀土取0.1~0.2 g,黄土取0.4~0.8 g,红土取0.2~0.4 g)和超声波分散时间(膨胀土取6 min,黄土和红土取2 min);激光粒度仪法试验结果的离散性,对于黄土和膨胀土较小,但对红土相对较大,红土平行试验中粒组含量极差的最大值为10.1%;与密度计法相比,激光粒度仪法测得的胶粒(0,0.002]mm含量偏小,而黏粒(0.002,0.005]mm或更大粒组的含量则偏大,可能是因为两者试验原理的不同而导致的;2种方法对红土的测试结果差异较大,与红土的特殊性质有一定关系。研究成果为激光粒度仪在特殊土颗粒分析试验中的应用提供了借鉴。

折反式激光粒度测量方法

激光粒度仪因其快速、非接触等优点被广泛应用于各领域的粒度分布测量,但颗粒散射光的角分布与粒度大小关系复杂。为了获得不同粒度下的相对精度一致,通常会造成粒度分布测量范围小、无法满足宽分布粒度测量要求等问题。根据Mie散射近似的菲涅尔原理,提出采用折反式光路,将颗粒散射信号由分光镜分成两束,经两组组合式镜头和2个光电探测器分别采集透射和反射的散射信号,信号组合后经反演得到颗粒粒度分布,从而提高了可测粒度范围。采用两种标准粒子及其混合物进行了实验,结果表明,单种标准粒子测量结果的体积中位径D50的测量相对误差都不大于7.9%;对混合粒子也能够得到正确的峰值分布。

碱性蛋白酶酶解蛋白制备活性肽的质控研究

以胶原蛋白和大豆分离蛋白为主要研究对象,应用体积排阻色谱(SEC)结合多角度激光光散射(MALLS)及示差折光(RI)联用技术对碱性蛋白酶酶解蛋白制备肽段的过程进行了详细分析。在酶解过程中,不同来源的胶原蛋白(牛、鸡)和大豆分离蛋白在分子量分布、体系的分散度及粒径变化规律上表现出了典型的差异。结果表明,牛胶原蛋白在酶解开始时就迅速被降解产生了大量小分子肽段,鸡胶原蛋白相对于牛胶原蛋白在相同的酶解条件下更难产生小分子肽段,大豆分离蛋白随着酶的加入则是表现出了先聚集再降解的特性。SEC-MALLS技术可以有效把控蛋白酶解的过程以及体系中肽段分子量分布,该技术可以为活性肽产品的开发及品质检测提供依据。

基于改进Morozov偏差原理的动态光散射粒度反演

与窄粒度分布反演相比,宽粒度分布的反演难以获取与其相适应的正则参数。为提高宽分布颗粒体系反演结果的准确性,提出基于改进Morozov偏差原理,通过遗传算法迭代求取正则参数的方法,该方法通过小波包分解求出电场自相关函数的噪声分量,利用Morozov偏差原理建立适应值函数,在正则参数经验范围内生成初始种群,将适应值函数与初始种群带入遗传算法,全局寻找最优适应值对应的参数值作为正则参数。模拟与实测数据的反演结果表明,在窄分布颗粒体系条件下,所提方法与L-curve准则反演结果无显著差异,在宽分布条件下,所提方法反演结果的性能指标均优于L-curve准则,且避免了宽粒度分布条件下可能出现的虚假峰情况,表现出明显优于L-curve准则的宽分布反演效果。

非高斯项对超低浓度动态光散射测量的影响

采用去除和保留非高斯项方法,分别反演了不同分布宽度颗粒的模拟动态光散射数据,并通过相应的光强自相关函数(autocorrelation function,ACF)与平均粒径对应的光强ACF间的差值,计算出不同分布宽度颗粒的粒度信息在光强ACF中的分布。结果表明,对于窄分布颗粒,在较低噪声水平下,去除与保留非高斯项对颗粒粒度分布反演无明显影响。随着噪声水平的增高,去除非高斯项反演的性能指标优于保留非高斯项。对于宽分布颗粒(变异系数一般大于3%),保留非高斯项则可得到更为准确的反演结果。产生上述结果的原因在于,不同分布宽度颗粒对应的非高斯项中的粒度信息含量不同。与窄粒度分布相比,宽分布颗粒对应的非高斯项包含更多的粒度信息,去除非高斯项会导致粒度信息丢失,从而降低反演结果的准确性。由于光强ACF的长延迟时段含有较多噪声,窄分布颗粒的反演不仅不能通过保留非高斯项获益,而且还会因噪声增加使反演结果的准确性降低。

基于全局阈值分割的泥沙粒度分布测量及校正

针对泥沙颗粒灰度图像中的噪声和边缘模糊问题,提出了一种新的基于全局阈值分割方法。通过利用背景像素的正态分布特征和像素灰度值的突变点作为参考阈值,实现了有效的阈值分割,进而采用SURF检测和FLANN匹配方法验证了图像分割的准确性和可靠性。构建了泥沙颗粒形状测定系统,通过线性修正方法对系统误差进行了修正,将误差范围控制在±0.01 mm以内。进一步将该方法与马尔文激光粒度仪法进行了比较分析。结果表明:在D50—D60尺度下,两种方法的测量结果基本一致;当颗粒粒径小于D50时,测量结果偏大,大于D60时,测量结果偏小,平均百分位偏差在±0.02 mm范围内,相对百分位偏差在7%以内,证明了该方法的可靠性。

激光衍射法测定西格列他钠粒径分布

目的建立西格列他钠的粒径分布测定方法,为药物粒径测定的方法开发和质量控制提供参考。方法采用MALVERN Mastersizer 3000激光衍射粒度仪和AEROS干法进样器建立西格列他钠的粒径分布方法。背景测量持续时间7 s;样品测量持续时间7 s;遮光度0.5%~5%;样品分散气压0.4 MPa;进样速度60%;文丘里管类型为高能文丘里管;料斗间隙2.5 mm。结果3批样品粒径分布特征值d(0.1)在1.02~1.17μm,d(0.5)在5.94~6.69μm,d(0.9)在20.70~22.40μm,平均标准偏差(RSD)均小于1%。结论建立了西格列他钠的粒度测定方法,可为其他易引湿药物的干法粒径测定方法开发提供参考。

激光粒度分析仪测试条件对粒径分析的影响

合适的激光粒度分析仪测试条件对于粒径分布数据的准确性至关重要。对比不同粒径粉末在欧美克LS-909激光粒度分析仪、SCF-105B湿法进样器中的测试结果并进行分析。结果表明,对于小于1μm的粉末样品,建议超声60 min以上,遮光率选择5%~8%,泵速选择2000~3000 r/min;对于几十μm的粉末样品,可不超声,遮光率选择10%~15%,泵速选择1500~2500 r/min;对于几百μm的样品,建议不超声,遮光率选择10%~20%,泵速选择2500~3500 r/min。在以上条件下测得的数据可靠且重复性高。