Determination Of Size Distribution Research Articles

Inverse association between serum endocan levels and small LDL and HDL particles in patients with type 2 diabetes mellitus.

Determination of lipoprotein size and subclasses distribution can provide more significant information on cardiovascular disease risk than measurement of traditional lipid parameters alone. Accordingly, we aimed to examine their potential relationship with the novel biomarker of endothelial dysfunction, such as endocan in patients with type 2 diabetes mellitus (T2D), since there are no studies concerning this issue. This case-control study included a total of 42 individuals with T2D and 64 diabetes-free participants. Serum endocan, lipid parameters, and lipoprotein subclasses were measured. Patients with T2D exhibited higher proportion of the smallest high-density lipoprotein (HDL) particles HDL 3c, as compared with diabetes-free participants (p=0.047). Higher serum endocan levels in T2D patients with low small dense low-density lipoprotein (LDL) particles (sdLDL) %, as compared with corresponding group of diabetes-free subjects was shown (p<0.01). Univariate binary logistic analysis revealed significant positive association of endocan and LDL diameter (OR=1.686, p=0.004), and negative associations of endocan with proportions of sdLDL (OR=0.928, p=0.007) and HDL3b (OR=0.789, p=0.009) particles. In a multivariate analysis, LDL diameter and proportions of sdLDL and HDL3b subclasses remained independent predictors of endocan levels in tested population. The results of our study showed that larger LDL diameters, but lower sdLDL and HDL3b proportions were associated with higher endocan levels in population with T2D. More studies in the future are needed to confirm the observed relationship and to examine its causal nature.

Data-driven model for the breakage of dry monodisperse agglomerates by wall impact applicable for multiphase flow simulations

The study is concerned with the development of a model for predicting the particle size distribution resulting from the impact of nearly spherical cohesive agglomerates at a wall under a variety of impact conditions. For the derivation of the model an extensive number of discrete element simulations is carried out. The matrix of impact conditions consists of eight agglomerate size classes between 10 and 104 primary particles and seven impact angles between a flat (7°) and a normal impact (90°). To include the effect of the van-der-Waals bond strength, three primary particle diameters in the micrometer range are considered. Furthermore, the range of velocities allows to reproduce the full breakage spectrum from a rebound of an intact agglomerate to a full disintegration. The model is intended for the application in Euler-Lagrange simulations based on the hard-sphere approach ignoring the time-consuming resolution and tracking of the detailed agglomerate structure. This allows the prediction of turbulent flows with high mass loadings. For the model derivation the impact outcome is quantified by measures enabling the determination of the particle size distribution, i.e., the overall number of resulting fragments (fragmentation ratio) and the number of primary particles incorporated in the three largest fragments. The results concerning the effect of different agglomerate and impact parameters are consistent with the reported literature. Relying on this broad data base a new physically meaningful dimensionless number πimp is derived based on an empirical approach to characterize the breakage phenomenon. The advantage of the proposed dimensionless number reasonably unifying the results obtained under widely varying impact conditions is demonstrated. In addition, the disagreement detected for some of the cases can be attributed to the re-agglomeration of detached fragments due to the van-der-Waals force. Since agglomeration is separately accounted for in the multiphase simulation approach targeted by the breakage model, the data influenced by high re-agglomeration rates are not considered in the derivation of the data-driven model.

Internal Volumes of Pharmaceutical Compendial Induction Port, Next-Generation Impactor With and Without Its Pre-separator, and Several Configurations of the Andersen Cascade Impactor With and Without Pre-separator.

Background: Determination of aerosol aerodynamic particle size distributions (APSD) from dry-powder inhalers (DPIs), following quality control procedures in the pharmacopeial compendia, requires that the flow through the measurement apparatus, comprising induction port, optional pre-separator, and cascade impactor, starts from zero on actuation of the inhaler, using a solenoid valve to apply vacuum to the apparatus exit. The target flow rate, governed by the inhaler resistance, is reached some time afterward. Understanding the behavior of the DPI design-specific flow rate-rise time curve can provide information about the kinetics of the initial powder dispersion in the inhaler and subsequent transport through the APSD measurement equipment. Accurate and precise measures of the internal volume of each component of this apparatus are required to enable reliable relationships to be established between this parameter and those defining the flow rate-rise time curve.Methods: An improved method is described that involves progressive withdrawal of an accurately known volume of air from the interior passageways of the apparatus-on-test that are closed to the outside atmosphere. This approach is applicable for determining internal volumes of components having complex internal geometries. Filling some components with water, along with volumetric or gravimetric measurement, has proven valuable for the induction port and for checking other measurements.Results: Values of internal volume are provided for the USP (United States Pharmacopeia)/PhEur (European Pharmacopoeia) induction port, the Next-Generation Impactor (NGI™) with and without its pre-separator, and various Andersen 8-stage cascade impactor configurations with and without their pre-separators.Conclusion: These data are more accurate and precise, and therefore update those reported by Copley et al.

Characterization of sugarcane bagasse particles separated by elutriation for energy generation

Bagasse particle is used in energy generation, and the usual method for determining their size distribution is sieving. Traditional methods for measuring the bagasse particle size distribution, such as sieving, do not evaluate the effect of the irregular particle shape, producing results that are not always applicable to the prediction of fluid dynamic behavior. This work determined size distribution of bagasse particles considering their aerodynamic behavior. Physical-chemical characterization was performed in different particle sizes of the bagasse. A particulate elutriation and settling system was developed to determine the terminal velocity distribution of particles. Drag coefficients and terminal velocities measured were compared with literature correlations. Almost all the correlations analyzed showed significant deviations from the values obtained experimentally. Haider and Levenspiel’s correlation showed the smallest average deviation. Two types of particles were observed in bagasse: fibers and spongy pith. The apparent density of the particles depends on the particle size, and the ash concentration in smaller fractions is 3 times larger than the average. The method of aerodynamic separation for the characterization of bagasse particle allowed to obtain information that cannot be found by the traditional method of separation by sieving.

COMPOSITION AND STRUCTURE OF THE NEPSKY AND TIRSKY FORMATION OF THE PRILENSK-NEPSKY STRUCTURAL-FACIES ZONE OF THE NEPA-BOTUOBA ANTECLISE BY THE RESULTS OF CORE MATERIAL STUDIES

Background. Clarification of the structure of sedimentary formations located on the Siberian Platform by means of lithological and petrographic core studies has a theoretical and practical significance for the creation of geological models for oil and gas prospecting and exploration works. Aim. To characterize and compare the composition of the upper Vendian of the central and southern parts of the Prilensk-Nepsky structural-facies zone. Materials and methods . Core samples for analysis were obtained from boreholes in the Preobrazhenskaya, Verkhnechenskaya, Danilovskaya, Yaraktinskaya and other areas. The article is based on the results of a layered lithological description of the cores from 15 wells with a total core output of 560 m in the interval of the Nepsky and Tirsky formations; the petrographic analysis of 540 thin sections; the determination of grain size distribution of rocks by laser light scattering in 220 samples; and X-ray diffraction analysis of 540 samples. Results . The Nepsky formation is represented by the following lithotypes: conglomerates, gravelites, sandstones, aleurolites and argillites. The section of the southern part of the structural-facies zone, compared to its central part, is characterised by increased claying. This is associated with the location of this zone in transitional coastal-marine environments, where large river systems were discharged carrying sandy-clay material into the basin. The source of the terrigenous rocks was felsic igneous rocks. The section of the Tirsky formation of the central part is represented (from bottom to top) by a transition from argillites and aleurolites to dolomites. In the section of the southern part, basal sandstones lie at the base, alternating upstream with clay-carbonate rocks. Conclusion . The material composition of the studied sediments reflects the specifics of sedimentation during the Nepsky and Tirsky time periods. For the first time, the Tirsky formation of the southern part of the structural-facies zone was divided into four lithological members. The formation of basal sandy rocks at the bottom of the sub-formations is associated with the stages of tectonic activity and positive tectonic movements that initiated relatively rapid weathering and transportation of terrigenous material from adjacent heights to the sedimentation basin.

Semantic segmentation: A modern approach for identifying soil clods in precision farming

Clod identification and determination of aggregate size distribution have undeniable importance in tillage operations, it affects other missions in the field regarding the energy issue. The objective of the study is accurate identification of clods based on a state-of-the-art method entitled semantic segmentation. In this regard, a deep network in the domain of deep learning was used. As the shape of clods on the surface of the ground is often irregular, object detection algorithms are unable to determine the boundary and, they only put a bounding box around the objects. Thus, there is a gap in this regard with deep learning based semantic segmentation filling this gap properly. In order to identify soil clods and compute their various geometrical specifications in different sizes and then to deal with the clods according to required action in variable-rate applicators, VGG16, which is a deep model, was used for implementing the semantic segmentation task. RGB images obtained from a stereo camera were used for feeding the proposed model as stereo cameras are relatively robust to the ambient light conditions and provide high resolution data in real field conditions. The pixels in each image of the dataset were divided into five groups of clod size, based on the equivalent diameter of each clod. These image pixels were labeled for training the network and extracting the required features. Finally, different soil clods were segmented and classified. A classical watershed segmentation was applied and the deep model was also trained in binary setting to evaluate the performance of the deep model and the results of the binary segmentations were compared. The mean accuracy and mean intersection over union (IoU) of the binary semantic segmentation reached 89.09% and 80.50%, respectively. Also, the watershed segmentation yielded 85.17% and 72.01%, for the same metrics. These results indicated that the semantic segmentation used in this study has significant advantages over the conventional watershed segmentation method.

New Prospects for Particle Characterization Using Analytical Centrifugation with Sector‐Shaped Centerpieces

AbstractAnalytical centrifugation (AC) has recently shown great potential for the accurate determination of particle size distributions. The well‐established LUMiSizer(R) is customized by a new design allowing for higher rotor speeds, improved thermal insulation, and measurement cell assembly. The latter enables sedimentation analysis of nanoparticles (NPs) in sector‐shaped centerpieces. The measurement window of AC experiments is assessed by the Peclet (Pe) number. It is shown that at low Pe numbers (0.7 &lt; Pe &lt; 30), sedimentation, and diffusion can be accurately and simultaneously analyzed from the sedimentation boundaries within one experiment. Moreover, sedimentation properties can be reliably determined up to Pe numbers of 4000. The thermal characteristic throughout the sedimentation analysis is validated by measuring polystyrene particles at elevated temperatures. Moreover, the performance of the setup is demonstrated by determining the sedimentation properties of SiO2 NPs at intermediate Pe numbers in excellent agreement with results from analytical ultracentrifugation experiments. Finally, for the first time, an accurate analysis of the core–shell properties of Au NPs via AC is presented. By combining the analysis of sedimentation and diffusional properties at low Pe numbers, the shell thickness of the stabilizer cetyltrimethylammonium bromide alongside the core diameter distribution of the Au NPs is determined.

The impact of cyclic fuels on the formation and structure of soot

This paper investigates the impact of cyclic fuels on the nanostructure, nucleation and overall production of soot in an n-heptane (C7H16) laminar coflow diffusion flame. The fuels selected to dope the n-heptane flame are cyclopentene (C5H8), cyclohexene (C6H10) and methylcyclohexane (C7H14). These fuels were chosen for their differences in their structure and sooting tendency. The flame structure was studied with Differential Mobility Spectrometry (DMS) for particle size distribution determination, two-colour ratio pyrometry to calculate the soot volume fraction and soot temperature. The soot nanostructure was investigated using Raman spectroscopy and high-resolution transmission electron microscopy (HRTEM). The addition of cyclic fuels was found to promote the formation of soot nanoparticles earlier in flames. In addition, the soot volume fraction was increased significantly by the addition of the cyclic fuels, especially by the addition of cyclopentene. The addition of 20% of cyclopentene increased the soot volume fraction by a factor of 2. HRTEM results suggest a significant influence of cyclopentene on the soot nanostructure; cyclopentene addition promotes the incorporation of five-membered rings (pentagonal rings) leading to highly curved fringes. This suggests cyclopentene could be used as a fuel to promote curvature in different carbonaceous materials to modify their properties.

Transferencia de oxígeno en una columna de tres fases utilizando polímeros sólidos como vectores de transferencia de masa

Three solid polymers; Kraton, Elvax, and Desmopan, previously suggested to be used in three-phase reactors, were evaluated for their ability to enhance oxygen transfer in a bubble column. These vectors were first characterized through determination of particle size distribution, surface roughness, specific surface area, density, void fraction and thermal stability. Oxygen transfer was then determined with a non-coalescing medium using polymer volume fractions from 0 to 75% in a 4 L bubble column operated at air flow rates ranging from 1 to 6 L/min. The results showed that the oxygen transfer was significantly improved in presence of 10 and 25% of Kraton and Elvax, compared with control experiment with no polymer. A maximum oxygen transfer improvement of 90%, compared with control, was observed with 10% Kraton. With Desmopan, no positive effect on oxygen transfer was observed regardless of the vector percentage used. Phase’s dispersion and oxygen transfer was further explored in presence of 10% Kraton. Gas holdup, Sauter mean bubble diameter and vector dispersion were characterized by means of high speed digital image analysis. The results showed that the enhancement of oxygen transfer mediated by Kraton was mainly caused by an increase of gas holdup and consequently of the gas/liquid surface area.

Determination of Size Distribution of Nanoparticles Using Asymmetric Flow Field-flow Fractionation (AF4)

Determination of Size Distribution of Nanoparticles Using Asymmetric Flow Field-flow Fractionation (AF4)

Experimental Method for the Determination of the Saturation Vapor Pressure above Supercooled Nanoconfined Liquids

For sorption studies, the saturation vapor pressure p0 above an adsorbate is of great significance. For example, it is needed for the determination of the pore size distribution, the Laplace pressure, and the chemical potential. Above the bulk triple point, T3bulk, this pressure is identical with the saturation vapor pressure above the bulk liquid. However, below T3bulk, the correct value of p0(T) is controversial. Nanoconfined fluids exhibit a shift of the freezing and melting temperatures in comparison to the bulk state. Thus, the adsorbed fluid is supercooled in a certain temperature range below T3bulk. Here, we show that it is possible to determine the appropriate saturation vapor pressure above the nanoconfined supercooled liquid experimentally. For this purpose, we have performed sorption measurements with liquid argon in nanoporous Vycor glass in the temperature range of the supercooled liquid and at temperatures above the bulk triple point. In order to determine the unknown and temperature-dependent saturation vapor pressure of the supercooled confined adsorbate, p0(T), we use the Kelvin equation relating this quantity to the pore radius, rP(p0), that is independent of temperature. The knowledge of the absolute values for the liquid–vapor surface tension of the supercooled adsorbate, γlv(T), is not required. However, we presuppose that its dependence on the unknown vapor pressure, γlv(p0), is bulk-like. Our results indicate that the saturation vapor pressure above the supercooled nanoconfined liquid corresponds to that above supercooled bulk argon (i.e., to the pressure obtained by an extension of the usual vaporization curve to T < T3bulk). We expect that this method can be used for the determination of p0 above other supercooled adsorbates.

INFLUENCE OF BACKGROUND ELECTROLYTE AND SURFACE-ACTIVE SUBSTANCES ON EFFICIENCY OF ELECTRO-FLOTATION EXTRACTION OF HARDLY SOLUBLE EUROPIUM COMPOUNDS

Europium and its compounds are widely used in high-tech processes of nuclear and hydrogen energy, electronics, medicine and other fields. In this work, the regularities of electroflotation extraction of hardly soluble europium compounds from model systems were obtained and analyzed. The aim of the work is to obtain data on the process of electroflotation extraction of hardly soluble europium (III) compounds from model systems with background electrolyte and the addition of surface-active substances, establishing optimal conditions for efficient extraction of hardly soluble europium (III) compounds. The research was conducted at room temperature (20 ± 2 °C) in a non- current electric flotator of periodic action, which is made in the form of a vertical column. The cross-sectional area of the electric flotator is 10 cm2, the volume of the treated solution is 500 ml, the height of the apparatus is 800 mm, and the sampling valve is located at a height of 40 mm from the electrode unit. The electrode unit consists of an insoluble anode made of ORTA (titanium with ruthenium oxide coating) and of a cathode made of stainless steel mesh (cell size 0.5 × 0.4 mm, wire thickness 0.3 mm). The mass concentration of europium (III) was determined by a mass-spectrometer with inductively coupled plasma of Termo Scientific brand. Determination of particle size and particle size distribution, surface charge of particles of the dispersed phase (ξ) were carried out using a Photocor Compact-Z laser particle analyzer. The efficiency of the process of extracting hardly soluble compounds of Eu3+ was evaluated by the degree of extraction α (%). The objects of study are colloid-dispersed systems of poorly soluble compounds of europium (III) in aqueous solutions in the presence of surface-active substances of various nature and background electrolytes. The initial aqueous solution contains: СEu3+ - 0.1 g/l, Cbackground electrolyte - 1 g/l, background salts: NaCl, NaNO3, Na2SO4; Csas - 5 mg/l. It has been shown that for each type of solution the efficiency of the electroflotation process is achieved at certain pH. It is established that the optimal conditions for the extraction of europium (III) compounds are: volume current density, Jv = 0.4 A/l; process duration 10 min. For nitrate background the degree of extraction is maximum at pH 10 - 11 and at the presence of an anionic surfactant additive in the solution (Оxy surfactant A1218). When extracting europium (III) compounds from a system with a sulphate background the best results were obtained at pH values of 8 and 10, as well as the addition of an anionic and, or cationic (Septa surfactant XEV70) surfactant. Chloride background showed the best conditions for the extraction of europium (III) at pH 7 with the addition of a non-ionic surfactant of PEO-1500 brand. The degree of extraction of europium is 98-99%.

Experimental evaluation of the in-the-field capabilities of total-reflection X-ray fluorescence analysis to trace fine and ultrafine aerosol particles in populated areas

European countries have made progress in reducing particulate air pollution in recent decades being concerned about their heath and climate effect. In addition to determining particulate number size distributions, it is crucial to have a methodology to determine size distribution of elemental concentrations down to the ultrafine size fraction. The present study shows capabilities for combination of May-type cascade impactor sampling and laboratory total-reflection X-ray fluorescence analysis on ambient aerosol samples taken in urban areas of Budapest (Hungary) and Cassino (Italy). In addition, results for a sample collected in Budapest during the fireworks provided for the Hungarian National Day are discussed.The combined novel method is suitable for determining size distributions for major and trace elemental concentrations form ultrafine to coarse particles (70 nm up to 10 μm) in seven size fractions. Moreover, short sampling times (1–4 h) are sufficient for reaching detection limits in the range of 100 pg/m3 for transition metals. The size and time resolution were found to be optimal for identifying pollution episodes with elevated elemental concentrations. The in-the-field analytical applicability of the proposed method for major and trace elements is demonstrated by comparison to elemental size distributions resulted from destructive analytical techniques.

Comparison of pipette method and state of the art analytical techniques to determine granulometric properties of sediments and soils

The determination of particle size distribution is a crucial issue in various fields of earth sciences (e.g., Quaternary research, sedimentology, stratigraphy, structural geology, volcanology), environmental sciences as well as diverse industrial applications (e.g., pharmaceuticals, cement industry). New measurement techniques developed as a result of industrial demands have also gained ground in environmental and Earth sciences research. The new techniques (especially laser diffraction) have enabled the particle characterisation in the broader size-range with a more detailed resolution. Still, they have to be compared with data obtained by classical methods. In light of the above, the primary aim of our research is to examine the methods of particle size determination critically. Excessive oversimplifications of particle size analyses routinely have used in paleo-environmental and paleo-climatological reconstructions, and other sedimentary studies, as well as insufficient knowledge of the background of the applied methods, distort the interpretation of the results. Over the past four decades, laser diffraction particle size analysers have proven to be practical tools of particle size characterisation. However, the shape of the natural sediment and soil particles are irregular and, therefore, affects the particle size distribution results obtained by different methods. The results of the traditional pipette method differed from laser diffraction results. The presence or absence of the pretreatments did control the differences between the two techniques. The results of Fraunhofer optical method were significantly different from Mie theory because it can detect much lower volume percentages of finer particles. Grain size results of coarse-grained samples measured by different laser diffraction devices were more comparable than the results of more clayey samples. The ratios of different sizes were changed due to the hydrochloric acid and hydrogen peroxide pretreatments. The comparison of different techniques is necessary to revaluate standards in grain size measurements which can enable the shift from conventional methods to more productive and reproducible methods. Still, light scattering techniques have not yet been able to displace classical methods in Earth sciences completely, in contrast to industrial applications.

Production of instant coffee from cold brewed coffee; process characteristics and optimization

This study aimed to develop a process for producing instant coffee from cold brewed Arabica and Robusta roasted coffee beans. The process starts by selecting an appropriate mixture of Arabica and Robusta coffee beans, degree of roasting (light, medium, dark) and degree of grinding (coarse, fine). Sensory evaluation by a trained panel showed that a mixture of 92.5% Arabica and 7.5% Robusta medium roasted, coarsely ground coffee beans produces instant cold brewed coffee equally or better accepted from other instant coffees available to consumers. The selected coffee beans were subjected to vacuum assisted cold extraction and the extract was spray dried. Spray drying conditions (inlet temperature, air volumetric flow and air aspiration rate) were optimized by a 33 full factorial design. Response variables were solids yield, process thermal efficiency and anti-oxidant capacity of the produced powder measured as %DPPH scavenging ability, FRAP and total phenolic content. The produced powder was analysed for its physicochemical characteristics (caffeine content, phenolics, moisture content, hygroscopicity, bulk density, solubility, particle size distribution, acrylamide content and shelf life determination).

Detectability of the τes−21cm cross-correlation: a tomographic probe of patchy reionization

The cross-correlation between fluctuations in the electron scattering optical depth τes as probed by future Cosmic Microwave Background (CMB) experiments, and fluctuations in the 21cm differential brightness temperature Δ T 21cm as probed by ground-based radio interferometers, will trace the reionization history of the Universe. In particular, the τes−21cm cross-correlation should yield a determination of the characteristic bubble size distribution and ionization fraction as a function of redshift. When assuming that the cross-correlation signal is limited by instrumental noise rather than by foregrounds, we estimate its potential detectability by upcoming experiments. Specifically, the combination of HERA and Simons Observatory, CMB-S4 and PICO should yield a signal-to-noise ratio around 3–6, while and the exploitation of the SKA should increase it to 10-20. Finally, we have discussed how such levels of detectability can be affected when (simply modeled) 21cm foregrounds are present. For the most promising PICO×SKA configuration, an efficiency of foreground removal to a level of 7× 10−4 is needed to achieve a 5σ detection of the cross-correlation signal; in addition, safe avoidance of foreground contamination in the line-of-sight Fourier modes above 0.03 h Mpc−1 would guarantee a detection significance around 3σ.

Digital UV/VIS imaging: A rapid PAT tool for crushing strength, drug content and particle size distribution determination in tablets.

The Process Analytical Technology (PAT) and the Quality-by-Design (QbD) approaches can efficiently facilitate the shift to the desired continuous manufacturing and real time release testing (RTRT). By this, it is vital to develop new, in-line analytical methods which fulfil the pharmaceutical requirements. The fast-developing digital imaging-based machine vision systems can provide revolutionary solutions not just in the automotive industry but in the pharmaceutical technology, as well. This study aimed to explore the capabilities of UV/VIS-based machine vision in tablet inspection as a PAT tool for the determination of compression force and crushing strength, drug content and drug distribution in tablets using meloxicam a yellow model drug. In the case of determining the compression force and crushing strength, the application of multivariate wavelet texture analysis (MWTA) based models provided relatively low prediction errors. To predict the drug content of meloxicam tablets CIELAB or RGB colorspace based algorithms were successfully developed and validated. UV/VIS imaging was also used to map the particle size distribution and spatial distribution of meloxicam, the results were compared to chemical maps obtained by Raman microscopy. Digital imaging combined with multivariate data analysis might be a valuable, high throughput, in-line PAT tool for automated inspection of pharmaceutical tablets.

Measurement of pore size distribution of building materials by thermal method

The present work focuses on the study of the thermophysical properties of low porous insulation materials. In peculiar, we investigate the pore structure of composite materials and cements by thermal method. This method, adapted for fragile materials, is based on an existing model which allows the determination of pore size distribution. Firstly, the existing analytical model is presented. The thermal conductivity is modeled by assimilating the studied medium to N fluid phases and one solid phase in series / parallel. Secondly, some extensions to this model are proposed. In particular, we show that in the case of a single pore size, it is possible to obtain a finer pore size distribution by means of a normal law. We also show for the first time that the normalization of the thermal conductivity is an interesting way to study the pore size distribution of a material without knowing the overall porosity rate (which strongly depends on the method used). Furthermore, this model and its extensions have been successfully applied to different kinds of materials (plant fiber composites and cements). Fibers reinforced composites have one class of pores around 30 – 60 μm. Chemical treatments do not affect this pore size. Cements show a macroporosity (around 20 μm) which is often underestimated.

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.