Determination Of Size Distribution Research Articles

Determination of full-scale pore size distribution of Gaomiaozi bentonite and its permeability prediction

Abstract Gaomiaozi (GMZ) bentonite is a potential buffer/backfill material for a deep geological disposal of high-level radioactive waste. It has a wide pore size distribution (PSD) with sizes ranging from several nanometers to more than one hundred microns. Thus, properly characterizing the pore structures of GMZ bentonite is a challenging issue. In this study, pressure-controlled porosimetry (PCP), rate-controlled porosimetry (RCP), and scanning electron microscopy (SEM) were used to investigate the PSD of GMZ bentonite. The results indicate that each method has its limitation, and a combined use of PCP and RCP is suitable to obtain the full-scale PSD of GMZ bentonite. Moreover, we also compared the full-scale PSD with nuclear magnetic resonance (NMR) result. It is found that there is no significant difference in the range of PSD characterization between NMR and mercury intrusion method (PCP and RCP). However, in a certain range, the detection accuracy of NMR is higher than that of mercury injection method. Finally, permeability prediction based on PCP and SEM data was conducted, and both of the two methods were found to be able to predict the permeability. The combined method is effective to obtain the full-scale PSD of GMZ bentonite, which is the key to estimation of the sealing ability of bentonite buffer.

Determination of Bubble Size Distribution Using Ultrasound Array Imaging.

In this article, ultrasonic phased arrays are deployed as an imaging tool for industrial process analysis. Such arrays are typically used for sonar, medical diagnosis, and nondestructive testing; however, they have not yet been applied to industrial process analysis. The precise positioning of array elements and high frequencies possible with this technology mean that highly focused images can be generated, which cannot currently be achieved using ultrasound tomography. This article aims to highlight the potential of this technology for the measurement of bubble size distribution (BSD) and to demonstrate its application to both intrusive and noninvasive process measurements. Ultrasound images of bubble reflectors are generated using the total focusing method deployed using a 32-element, 5-MHz linear phased array, and an image processing algorithm for BSD determination is presented and evaluated under stationary and dynamic acquisition conditions. It is found that the sizing accuracy is within 10% for stationary reflectors larger than 4λ in diameter and that the algorithm is stable across the expected spatial variation of reflectors. The phased array is coupled to a six-axis robotic arm to scan a solid sample containing bubble reflectors at velocities up to 500 mms-1. The sizing accuracy is within 45% for bubbles larger than 4λ in diameter and at velocities up to 300 mms-1. However, above this velocity, the algorithm breaks down for reflectors smaller than 9λ in diameter. The ultrasound system is applied to a stream of air bubbles rising through water, which is verified via photographic analysis. Images were generated both intrusive and noninvasive, via a 10-mm Perspex barrier, to the process stream. The high bubble density in the process stream introduced scattering, limiting the measurement repeatability and the sample size in the measured distribution. Notwithstanding, this result demonstrates the potential of this technology to size bubbles for intrusive and noninvasive process analyses.

Particle size determination from magnetization curves in reduced graphene oxide decorated with monodispersed superparamagnetic iron oxide nanoparticles

Reduced graphene oxide (RGO) decorated with superparamagnetic iron oxide nanoparticles (SPION) is a novel composite nanomaterial with a myriad of promising applications. However, processes such as the fast and simple synthesis of non-agglomerated monodispersed SPION on RGO and the accurate characterization of particle size distributions remain challenging. Here we present how to solve these two problems. Firstly, we introduce a new microwave-assisted synthesis of stabilized SPION on RGO which is fast, simple and up-scalable but at the same time renders well dispersed SPION with narrow size distributions. The coverage of the RGO flakes with SPION is extensively tuned and the results are compared with a non-stabilized microwave-assisted method. Secondly, we implement an accurate method for the determination of particle size distributions from magnetization curves in RGO-SPION composite nanomaterials. This method is applied to the prepared composites with different particle size distributions, degrees of particle agglomeration and coverage of the RGO flakes. The influence of sample characteristics in the size determination method is discussed and the results are compared with the values obtained from transmission electron microscopy (TEM) and X-ray diffraction (XRD), showing that the method is well suited for these and potentially other types of superparamagnetic composite nanomaterials.

Determination of particle size distributions and transformation enthalpies from the temperature course of a phase transformation

The presented analysis of the temperature course of a phase transformation of nanoparticles offers a powerful tool to obtain data for the particle size distribution and the enthalpy of transformation. The analysis starts with the temperature distribution within an ensemble of nanoparticles and a functional relation between particle size and transformation temperature. In contrast to the Maxwell-Boltzmann distribution, in case of nanoparticles, the distribution of the temperature of the particles follows a normal distribution. Finally a reliable characterization of the specimen and the transformation in question are presented. These results, particularly the particle size distribution, represent – in many cases – a statistically more significant result as compared to the outcome, obtained by evaluation of electron micrographs. Looking at the problems of microcalorimetric determination of reaction enthalpies, one may realize comparable problems. By comparison of the experimental data with the calculated ones, one may obtain additional information about the interaction of the particles within the ensemble.

Expression of key myogenic, fibrogenic and adipogenic genes in Longissimus thoracis and Masseter muscles in cattle

Adipogenesis, myogenesis and fibrogenesis are related processes that can contribute to meat quality. Therefore, extending the knowledge of these processes would facilitate the identification of molecular markers that predict intramuscular fat accretion. The main purpose of this work, based on previous results, was to further study the expression of key genes related to adipogenic, myogenic, fibrogenic processes and some cytokines in Longissimus thoracis (LT) and Masseter (MS) muscles of Pirenaica and Holstein young bulls. Longissimus thoracis and MS muscles from Pirenaica (n = 4) and Spanish Holstein (n = 4) were sampled for proximate analysis, determination of adipocyte size distribution and expression of key candidate genes. Fat percentage was lower in LT than in MS muscle in Pirenaica young bulls (P = 0.023) and was higher in LT muscle in Holstein than in Pirenaica young bulls (P = 0.007). Gene expression analysis revealed that the mRNA level of myogenic differentiation 1 (MYOD) was higher in LT than in MS muscles in both groups of animals (P < 0.001) and that myostatin (MSTN) expression was also higher in LT than in MS muscle in Holstein bulls (P = 0.001). On the other hand, MSTN and PPARG showed higher expression in LT and MS in Pirenaica young bulls (P = 0.026), while the expression of fatty acid-binding protein 4 (FABP4) was higher in Holstein young bulls, also in both muscles (P < 0.001). The results suggested that the development of intramuscular adipose depot was directly related to the expression of adipogenic genes, such as FABP4, but inversely related to the expression of the cytokine MSTN and the myogenic gene MYOD, genes which showed a muscle-specific expression.

ДІАГНОСТУВАННЯ ГЕНЕТИЧНИХ ОСОБЛИВОСТЕЙ ЧОРНОЗЕМНИХ ҐРУНТІВ МЕТОДАМИ МАГНІТОМЕТРІЇ

The ecological-genetic status of soil is determined by the course of the soil-forming process and is the main factor in optimizing the agricultural use to achieve a sustainable state. The definition of a qualitative indicator of this status (KVAG) is developed in Ukraine and is characterized as costing and resource intensive. To solve the problem, it is proposed to replace agrochemical methods with less costly magnetic ones. The purpose of the study is to show the informativeness of geophysical methods for the indication of the process of pedogenesis on the example of chernozems podzolized of Kharkiv region. We used the standardized studies of determination of organic carbon content, determination of the particle size distribution of soil, and pH analysis. The characteristic of the sampling site on the slope was performed by determining the erosion hazard index. The mass-specific magnetic susceptibility of soil (MS) was determined and then calculated. The study sites were located at the area of distribution of chernozems podzolized in the northern part of Kharkiv district and the central part of Pechenigy district of Kharkiv region. Soil genetic identity has been determined initially at the large-scale survey map and refined by field studies. The erosion processes complicated the soil study at the slope. We registered high informativeness of MS for the indication of genetic status. MS is relevant to use not only within a single agrocenosis, but also in agrolandscapes for soils which pedogenesis is complicated by hydromorphism. The experiment was performed at one-lane terrace of the Siverskyi Donets River, where soils of varying degrees of hydromorphism are developed. Magnetic methods have significant outlook for their application in soil studies. The example of the podzolized soils investigation of Kharkiv region shows the possibility of the identification of hydromorphic processes in the lower part of the soil profile (decrease of the values of MS compared to the background). The example of the arable land shows the possibility of replacing the high-cost determining of the humus content by much cheaper MS as the indicator of ecological-genetic status of soil (KVAG). The correlation coefficient between the KVAG and KVAMS (based on the MS measuring) is: ρ = 0.901.

The influence of metal phase composition on microstructure and mechanical properties of Al2O3-Cu-Cr ceramic metal composites

Ceramic metal composites from the ternary Al2O3-Cu-Cr system were fabricated with the use of the slip casting method. Densities of the obtained composites with 15 vol.% of metal content and different percentage composition of Cu and Cr were examined by the Archimedes method. The samples’ microstructures, observed by scanning electron microscope, were analysed with image analysis program in order to determine size distribution of the metallic areas in the structure. Phase composition of the sintered samples was examined by X-ray diffraction analysis. Vickers hardness of the samples was tested along with their fracture toughness with the use of the Vickers indentation technique. The conducted research revealed the correlation between the microstructure and mechanical properties of the obtained specimens. It has demonstrated the possibility of manufacturing composites from ternary system with the use of the slip casting method. It was revealed that the addition of the chromium particles to the metallic phase enhances hardness of the composites. Also, the metallic phase composition of the samples affects mechanism of the crack propagation in the material. Although the mechanical properties have been improved, it was found that the density of the samples was not satisfying and the need for further analysis has been identified.

The Effect of Powder Characteristics on Build Quality of High-Purity Tungsten Produced via Laser Powder Bed Fusion (LPBF)

Two high-purity tungsten powders, produced via different manufacturing techniques, were characterized to determine size distribution, morphology, thermal properties, and flow characteristics and, thus, the likely suitability for Laser Powder Bed Fusion (LPBF) production. Specimens from duplicate builds were produced with the two powders and characterized for density, defect mechanisms, and thermal penetration into the substrate plate to compare apparent power densities. The first powder was a chemically reduced powder with irregular morphology and the second, a plasma spheroidized powder with highly spherical morphology. The latter was found to have tighter morphological control and size distribution, having a third of particles at the modal particle size in comparison to a fifth of the chemically reduced powder. This led to better flow characteristics, and an increase of 1.5 g cm−3 (1500 kg m−3) in the packing densities seen in the powder bed which corresponds to 57 pct theoretical density vs 50 pct theoretical density in the chemically reduced powder. As a result, the specimens produced from the plasma spheroidized powder had higher densities (97.3 vs 88.5 pct) and the dominant defect mechanism moved from lack of fusion dominated in the chemically reduced powder to cracking dominated in the plasma spheroidized. The plasma spheroidized powder also showed higher apparent power densities (effective absorptivities) as evidenced by an 80 pct deeper penetration of the laser into the substrate plate.

Passive Acoustic Method in Bubble Size Distribution Determination

The paper is considering existing methods for determining the gas phase hydrodynamic properties in liquid medium. This paper presents a passive hydroacoustic method for determining the air bubbles size distribution in water. Advantage of this method contrasting to the active ones lies in its invasiveness. Mathematical model proposed for converting the spectrum of noise emitted by a cloud of bubbles into size distribution was tested in a number of experiments. Experiments were carried out in a glass cubic reservoir filled with water. Experiment results were verified by comparison with the photometric method.

Determination of particle size distribution based on dynamic light scattering measurements in the near field

Particle size distribution (PSD) measurement is important for improving product quality, inhibiting environmental pollution, and safeguarding human health. The near-field scattering (NFS) technique offers many substantial advantages over conventional techniques. However, the reconstruction equations are ill-posed and it is difficult to get a reliable solution. In this paper, we propose a new method that can solve the reconstruction equations. This method combines the Backus-Gilbert eclectic theory with truncated singular value decomposition (TSVD) method to obtain a non-negative approximation solution as the initial value of Chahine algorithm for fine calculation. Our method exhibited good performance with several numerical cases of unimodal and bimodal PSDs. It was then used for PSD measurement of two standard particles (GBW(E) 120,028 and 120,047) using the NFS techniques. The relative errors of the length mean diameter, with respect to the peak size of these two standard particles, were 0.18% and 0.76%, respectively.

An easy and innovative one-step in situ synthesis strategy of silica nanoparticles decorated by graphene oxide particles through covalent linkages

This research work presents the development of an easy synthesis method for functionalized and covered graphene oxide (GO) nanosheets with silica nanoparticles through one-step in situ sol-gel approach by using two different silane molecules: a tetraethylorthosilane (TEOS) grafted with N (β-aminoethyl)-γ-aminopropyltrimethoxysilane (Z6020) and a TEOS with γ-aminopropyltriethoxy-silane (A1100). Both synthetized GO/SiO2-Z6020 and GO/SiO2-A1100 nanoparticles were characterized and compared in terms of exfoliation level, GO chemical partial reduction and self-condensation efficiency of silica nanoparticles over carbon planes. This way, microstructural and morphological analysis were performed using UV-visible, Fourier Transform InfraRed and Raman spectroscopies, Wide Angle x-rays Scattering, scanning electron microscopy, confocal optical microscopy and thermogravimetric analysis. Laser granulometry and zeta potential measurements on colloidal solutions in water allowed the determination of the particles size distribution and dispersion quality of these nanohybrid materials.

Determination of Size Distribution of Precipitation Aggregates Using Non-Invasive Microscopy and Semiautomated Image Processing and Analysis

Particle size distribution (PSD) determination is a typical practice for the characterization of the slurries generated in a precipitation plant. Furthermore, the precipitates generated in these processes form colloidal or aggregated suspensions. Nevertheless, the conventional methods used to estimate PSD (e.g., laser diffraction and/or a cyclosizer) have not been designed to measure particles that tend to aggregate or disaggregate, since they include external forces (e.g., centrifugal, agitation, pumping and sonication). These forces affect the true size of the aggregates formed in a unit operation, thereby losing representativeness in terms of aggregates particle size. This study presents an alternative method of measuring the size distribution of particles with aggregation behavior, particularly, by using non-invasive microscopy and image processing and analysis. The samples used were obtained from an experimental precipitation process by applying sulfidization to treat the cyanide-copper complexes contained in a cyanidation solution. This method has been validated with statistical tools and compared with a conventional analysis based on laser diffraction (Mastersizer). The PSD results obtained with optical microscopy show a bi-modal behavior of the precipitates. However this behavior could be not determined when using the laser diffraction technique. The PSD obtained for the sample tested by microscopy had a mean of 119.7 μm, a median of 147 μm and a 90% distribution reached a particle size of 312.5 μm. These values differ with those obtained by the laser diffraction technique. Our results show significant differences between the methods analyzed, demonstrating that the image processing and analysis obtained by optical microscopy is an excellent and non-invasive alternative to obtain size distributions of aggregates in precipitation processes.

Presentation of three dimensional geometric characteristics of food porous systems in the form of statistical functions

The article discusses the method of representing the three dimensionless geometric characteristics of porous materials in the form of statistical functions. The technique allows to obtain formulas for histograms of porous materials. The study relates to the analytical development of a method for determining the dimensionless parameters of food porous media. As an example, we consider a porous material similar in geometrical characteristics to a typical food product with a homogeneous and isotropic porous medium similar to starch, finely divided food additives, and flour. The study is based on the statistical lognormal distribution of random variables and the analytical relationship between the three dimensionless integral parameters of porous systems. The formulas of three dimensionless geometric parameters of a porous medium are obtained analytically: discontinuity, transparency, and porosity. They take into account the statistics of random pore size distribution. The formulas include an experimental integral parameter of porosity, defined by standard techniques. It corrects the results of the automated determination of the pore size distribution. The formulas allow calculating the influence of individual size groups of pores or of their entire size ensemble, which is important in calculating heat and mass transfer processes in porous food, chemical and other technologies. The considered technique allows to apply it in similar studies for statistical tasks of various types.

Wolfgang Beyer: A Groundwater Scientist from Dresden.

Wolfgang Beyer: A Groundwater Scientist from Dresden.

Applying photogrammetry and semi-automated joint mapping for rock mass characterization

Rock engineering in blocky rock masses demands a sound knowledge about the joint network, since it consists of planes of weakness than can lead to block instabilities. However, collecting data about the joint network is time consuming, seldom very detailed and depends strongly on the experience of the mapping geologist. Additionally, the characterization is reduced to the identification of the most relevant joint structures with their characteristic orientation and spacing. Other parameters, like the in situ block shape and the block size distribution or the main orientation of the blocks are seldom collected or determined, if at all. With the emergence and increasing application of digital surface mapping techniques in rock mass characterization, like ShapeMetriX3D or the Discontinuity Set Extractor, the time needed on site could be reduced and the degree of detail in the mapping of discontinuities is improved significantly. The work presented in this study displays a continuous work flow from the data collection in the field to the determination of the block size and shape distribution, generated by the intersection of joint sets. For the process, a marble quarry in Styria (Austria) was digitized, using photogrammetry. The joint sets are semi-automatically identified with the Discontinuity Set Extractor whose results are transferred into the software ShapeMetriX3D, where the joint set spacing along with its standard deviations are determined. These parameters are used to generate statistical representation of representative rock mass units, using 3DEC (Itasca Consulting Group, Inc.) and determine the block sizes, block shapes and main orientation of the blocks in a row of simulations.

Size fractionation of magnetic nanoparticles by magnetic chromatography

Magnetic chromatography is a promising method for fractionation of magnetic nanoparticles with respect to their size and/or magnetic properties. In this study, we investigate the effect of different magnetic field sources and operation modes on the retention of magnetic nanoparticles which pass through a chromatographic column filled with a fine magnetizable matrix. For nanoparticles in the size range between 50 and 400 nm, both constant magnetic fields and square wave AC fields with amplitudes of around 2 mT, result in retention factors of up to 2, while still showing good particle recoveries of more than 95%. In contrast, when using the ‘on-off’ magnetic field operation reported previously, retention factors of only 1.4 could be achieved. We also demonstrate that single domain magnetic nanoparticles show retention factors of 1.2–1.4 even without the application of an external magnetic field, due to their spontaneous magnetization. By using a combination of online UV-measurement and sample collection followed by the determination of the particle size distribution (PSD) by dynamic light scattering, a quantification of the fractionation efficiency could be achieved. Despite the short column of only 12 cm and the high specific throughput of more than 30 column volumes per hour a separation sharpness of 0.62 could be attained, demonstrating the high potential of the method for scalable nanoparticle fractionation.

Airborne nanoparticle (Nanoaerosol) sampling efficiency analysis based on filtration on TEM grid

The scientific and technological issues associated with the characterization of the exposure of nano-aerosols is a huge technological challenge. Nano-aerosol measurement is a key point to characterize nanoparticle exposure. Transmission electron microscopy (TEM) coupled with energy-dispersive X-ray (EDX) is a comprehensive tool for determining size distributions and elemental compositions. Individual particle analysis allows the determination of size, morphology, specific surface, and elemental composition. Techniques allowing sampling on adapted analysis support TEM grids are of great interest to aerosol analysis: by using MPS and TEM analysis, sampling is directly and easily performed. The current paper explores the available theoretical models which assess sampling efficiency according to the chosen empirical approach. The recent studies which use this method are also briefly introduced.

Determination of the size distribution of monodesperse and bidisperse mixtures of spherical particles in the nanometer and submicron size range by applying cumulant analysis and contin algorithm in dynamic light scattering

تعیین اندازه ذرات یکی از نیاز‌های مهم در صنعت و بیوتکنولوژی به شمار می‌رود. پراکندگی دینامیکی نور (DLS) یکی از پرکاربرد‌ترین روش‌ها در تعیین توزیع اندازه ذرات کروی در مقیاس نانو و زیر- میکرون است. در این روش الگوریتم‌های متفاوتی برای تعیین اندازه و توزیع اندازه ذرات وجود دارد، که با توجه به دقت مورد نیاز و همچنین نمونه مورد آزمایش انتخاب می‌شوند. در این پژوهش، مروری بر نظریه پراکندگی دینامیکی نور و الگوریتم‌های متداول تعیین اندازه ذرات انجام شده است. دقت و محدوده عملکرد تحلیل تجمعی (cumulant) و الگوریتم تداومی (contin) در بازه گسترده‌ای از اندازه ذرات استاندارد پلی‌استایرن در محدوده نانو و زیر- میکرون (900-20 نانومتر) به صورت تجربی بررسی می‌شود. نشان داده می‌شود که اندازه ذرات استاندارد به دست آمده توسط هر دو الگوریتم، با اندازه گزارش شده توسط شرکت سازنده مطابقت دارد. از آنجا‌یی‌که اغلب نمونه‌های مورد بررسی ذرات هم‌اندازه با توزیع اندازه باریک نیستند، نمونه‌های ترکیبی متشکل از دو ذره استاندارد با اندازه متفاوت، توسط هر دو رهیافت برای بررسی عملکرد DLS در نمونه‌های غیراستاندارد مورد آزمایش قرار گرفتند. تحلیل تجمعی اندازه‌ای را گزارش می‌کند که با اندازه هیچکدام از ذرات برابر نیست. اما مقدار شاخص بس ‌پراکندگی نشان‌دهنده توزیع اندازه بسیار گسترده نمونه است. الگوریتم تداومی هم تنها یک اندازه را گزارش می‌کند که با اندازه هیچکدام از ذرات برابر نیست اما به اندازه ذره بزرگ‌تر نزدیک است. نتایج به دست آمده از هر دو الگوریتم نشان‌دهنده عدم توانایی روش پراکندگی دینامیکی نور در تعیین اندازه ذرات در نمونه‌های ترکیبی مورد آزمایش است.

Hydrogeological Properties of Gypseous soils in South Africa

Abstract Gypseous soils occur in the western arid and semi-arid regions of South Africa and Namibia. These soils exhibit a complex nature and abnormal behaviour due to their gypsum content and as such they have become more prevalent in research. As these soils are finding more use in industry, an astute understanding of their hydrogeological properties and behaviour is required. Powdery gypseous soil samples collected from the Northern Cape (Geelvloer) and Western Cape (Rooiberg and R355) Provinces, as well as a prepared sample, are subject to XRD analysis, particle size distribution determination and falling-head permeability tests using both water and brine. The testing served as preliminary research to guide further studies into the topic. The prepared sample, with 19% fines, comprises 35% gypsum and 65% sand. Geelvloer samples, with 91.95% gypsum content, are comprised mostly of sand-sized particles with 45% fines. Rooiberg samples contain 75% fines with a slightly lower gypsum content of 83.25%, while R355 samples have 50% fines with 75.35% gypsum. It is generally understood that particle size distribution contributes to the hydraulic conductivity of soils, where a higher portion fines will result in a lower conductivity. In the case of gypseous soils, the solubility is of importance as well, as it may have long term effects. With the intent of evaluating the effect of the aforementioned factors on the hydraulic conductivity of gypseous soils in South Africa, the samples taken represent differences in particle size distribution and origin. Geelvloer had k-values in the order of 8.82×10-6 m/s, with the brine sample giving 9.43×10-6 m/s, while the k-values for Rooiberg and R355 were in the order of 3.90×10-6 m/s and 5.87×10-6 m/s, respectively. The brine resulted in 5.63×10-6 m/s for Rooiberg and 9.90×10-6 m/s for the R355 sample. The made sample, having less fines, had k values in the order of 2.15×10-5 m/s, and 4.19×10-5 m/s for the brine. The differences between the results are largely negligible and show that despite what is believed to influence the hydraulic conductivity, in the case of gypseous soils in South Africa, on a small scale, it remained unaffected.

Chitosan Nanoparticle for Loading and Release of Nitrogen, Potassium, and Phosphorus Nutrients

In the present study, chitosan nanoparticle (Ch NP) was prepared by polymerizing methacrylic acid for loading of nitrogen (N), potassium (K), and phosphorus (P) nutrients as fertilizer. Nutrient loading was done by suspensions of Ch nanoparticles with urea, calcium phosphate, and potassium chloride as sources of N, P, and K, respectively. The products were characterized by dynamic light scattering for determination of size and size distribution, zeta potential for signification of surface charge, scanning electron microscopy for investigation of size and morphology, Fourier transform infrared spectrum for characterization of functional group, UV–Vis spectroscopy for phosphorus loading, atomic adsorption spectroscopy for potassium loading, and KJDAL digestion method for nitrogen loading. The amount of nutrient release was investigated after 168 h in water solution at room temperature. According to the results, nutrient loading caused the increase in the size and the decrease in the stability due to loaded components. However, the percentage of nutrient loading differs not so much, but the percentage of nutrient release differs. Based on the obtained results, Ch NP is a good candidate as fertilizer for agricultural applications.