Dry Particle Size Research Articles

Robust magnetic vivianite recovery from digested sewage sludge: Evaluating resilience to sludge dry matter and particle size variations

Phosphorus recovery via vivianite extraction from digested sludge has recently gained considerable interest. The separation of vivianite was demonstrated earlier at the pilot scale, and operational parameters were optimized. In this study, we tested the robustness of this technology by changing the sludge characteristics, such as dry matter, and via that, sludge viscosity, and vivianite particle size. It was proven that the main factor influencing recovery was the concentration of vivianite in the feed. The technology can extract vivianite even when the sludge has higher dry matter (1.8% - 3.3%) and, therefore, higher viscosity. Smaller vivianite sizes (< 10 µm) can still be recovered but at a lower rate. This made magnetic separation applicable to a wide range of wastewater treatment plants.

Intranasal Vaccine Formulation: Advancing Towards Nasal Dry Powder Formulation

Unlike conventional mRNA vaccines,intranasal vaccines display several advantages, including the ability to generatestrong mucosal immunity. However,the formulation challenges associated with intranasal mRNA vaccines have so farhindered their extensive application and further research in the area of formulationdevelopment and optimisation are required before translation. This study aimsto optimise the manufacturing conditions of inhalable dry powders by examining theimpact of temperature and lipid composition on liposome particle size and theeffect of spray-drying parameters on the particle size of spray-dried powders. The results indicate that liposomesgenerated at 20°C exhibited notably larger sizes than those produced at 55°C,irrespective of the lipid composition. Notably, dry powder formulations featuringlarger particle sizes were achieved at a low gas flow rate of 25mm.

Effects of several factors in accelerated carbonation on neutralization and carbon dioxide capture of alkaline sludges treated with paper sludge ash-based stabilizer

Recently, a technology was developed in Japan to accelerate the carbonation of alkaline construction sludge and reduce its alkalinity. Alkaline construction sludge is treated in advance using a paper sludge ash-based stabilizer (PSAS) so that it becomes granular and well aerated. Subsequently, CO2 gas is injected from the bottom to the top of the treated sludge layer in the underground pit. This technology can reduce the pH of alkaline sludge within short periods; however, the completion period of pH neutralization has often been predicted empirically. This may be due to the combined effects of density, water content, particle size, PSAS amount in the sludge, and CO2 concentration in the accelerated carbonation on the pH neutralization process. However, there have been few studies on how these factors affect the pH neutralization and CO2 capture of PSAS-treated alkaline sludges subjected to accelerated carbonation. Therefore, in this study, the effects of several accelerated carbonation factors on neutralization and CO2 capture from alkaline sludge were experimentally investigated. PSAS-treated alkaline sludges with different densities, water contents, particle sizes, and amounts of PSAS were cured in incubators with controlled CO2 concentrations. Based on the pH measurements, the pH neutralization completion period (tN) was evaluated for each alkaline sludge sample. The test results revealed that tN increased with increasing dry density and particle size and decreasing CO2 concentration. The results also suggest that tN increases with increasing amounts of PSAS. However, the water content had a more significant effect on tN than the PSAS amount. There may be an optimum water content for pH neutralization if conditions other than the water content are the same. From the results of the carbonate content evaluation, the amounts of CO2 captured in each specimen (mCO2) and mCO2 at tN were determined for each alkaline sludge sample. The results revealed that the density, water content, particle size of the alkaline sludge, and CO2 concentration in the incubators did not significantly affect the amount of CO2 captured by the sludge (mCO2) upon the completion of pH neutralization. However, the amount of PSAS significantly affects the captured CO2 content. A higher amount of PSAS caused mCO2 to increase at tN.

Effects of corn silage and grain expressing α-amylase on ruminal nutrient digestibility, microbial protein synthesis, and enteric methane emissions in lactating cows

Increasing ruminal starch digestibility has the potential to improve microbial protein synthesis (MPS), milk production, and feed efficiency. Enogen corn (Syngenta Seeds LLC) expresses high α-amylase activity, and we evaluated effects of Enogen corn silage (CS) and grain (CG) on ruminal starch digestibility, MPS, and milk production in lactating dairy cows. Fifteen Holstein cows (6 ruminally cannulated and 9 noncannulated; average ± standard deviation at the beginning of the trial: 170 ± 40 d in milk; milk yield, 37.2 ± 7.73 kg/d; body weight, 714 ± 37 kg) were used in a replicated 3 × 3 Latin square design (28 d per period) with 3 treatments: a diet containing isoline CS and CG (control, CON); a diet with Enogen CS and isoline CG (ECS); and a diet with Enogen CS and CG (ECSCG). Dry matter (DM; 30%), starch (35% of DM), and particle size distribution of the isoline and Enogen CS were similar. However, the mean particle size of Enogen CG was larger (1.05 vs. 0.65 mm) than that of the isoline CG. Cannulated cows were used for digestibility and nutrient flow measurements, noncannulated cows were used for enteric CH4 measurements, and all cows were used for production evaluation. Dry matter intake (DMI) and milk yield were greater for ECS and ECSCG compared with CON (26.7 and 26.6 vs. 25.1 kg/d and 36.5 and 34.1 vs. 33.1 kg/d, respectively) without a difference between ECS and ECSCG. Milk protein yield was greater (1.27 vs. 1.14 and 1.17 kg/d) for ECS compared with CON and ECSCG. Milk fat content was greater (3.79 vs. 3.32%) for ECSCG compared with ECS. Milk fat yield and energy-corrected milk did not differ among treatments. Ruminal digestibilities of DM, organic matter, starch, and neutral detergent fiber were not different among treatments. However, ruminal digestibility of nonammonia, nonmicrobial N was greater (85 vs. 75%) for ECS compared with ECSCG. Total-tract apparent starch digestibility was lower (97.6 and 97.1 vs. 98.3%) for ECS and ECSCG compared with CON, respectively, and tended to be lower (97.1 vs. 98.3%) for ECSCG compared with ECS. Ruminal outflows of bacterial OM and nonammonia N tended to be greater for ECS than for ECSCG. Efficiency of MPS tended to be greater (34.1 vs. 30.6 g of N/kg of organic matter truly digested) for ECS versus ECSCG. Ruminal pH and total and individual short-chain fatty acid concentrations did not differ among treatments. Concentration of ruminal NH3 for ECS and ECSCG was lower (10.4 and 12.4 vs. 13.4 mmol/L, respectively) compared with CON. Methane per unit of DMI decreased for ECS and ECSCG compared with CON (11.4 and 12.2 vs. 13.5 g/kg of DMI, respectively) without a difference between ECS and ECSCG. In conclusion, ECS and ECSCG did not increase ruminal or total-tract starch digestibility. However, the positive effects of ECS and ECSCG on milk protein yield, milk yield, and CH4 per unit of DMI may show potential benefits of feeding Enogen corn. Effects of ECSCG were not apparent when compared with ECS, partly due to larger particle size of Enogen CG compared with its isoline counterpart.

Annual cycle of hygroscopic properties and mixing state of the suburban aerosol in Athens, Greece

Abstract. The hygroscopic properties of atmospheric aerosol were investigated at a suburban environment in Athens, Greece, from August 2016 to July 2017. The growth factor distribution probability density function (GF-PDF) and mixing state were determined with a hygroscopicity tandem differential mobility analyser (HTDMA). Four dry particle sizes (D0) were selected to be analysed in terms of their hygroscopic properties at 90 % relative humidity. The annual mean GFs for D0 = 30, 50, 80 and 250 nm were found to be equal to 1.28, 1.11, 1.13 and 1.22, respectively. The hygroscopic growth spectra were divided into two distinct hygroscopic ranges: a non- and/or slightly hygroscopic mode (GF &lt; 1.12) and a moderately hygroscopic mode (GF &gt; 1.12), which are representative of a suburban environment influenced by local/urban emissions and background aerosol. The standard deviation σ of the GF-PDF was employed as a measure of the mixing state of ambient aerosol. The 30 nm particles were mostly internally mixed, whereas larger particles were found to be externally mixed, either with a distinct bimodal structure or with partly overlapping modes. Cluster analysis on the hourly dry number size distributions was performed to identify the link between aerosol hygroscopicity and aerosol emission sources and formation processes. The size distributions were classified into five groups, with the “mixed urban and regional background” aerosol (67 %) and the “fresh traffic-related particles” from the neighbourhood urban area (15 %) accounting for more than 80 % of the results. The hygroscopic properties for 50 and 80 nm were found to be similar in all cases, indicating particles of similar nature and origin across these sizes. This was also confirmed through the modal analysis of the average number size distributions for each cluster; the 50 and 80 nm particles were found to belong to the same Aitken mode in most cases. The 250 nm particles (i.e. accumulation mode) were generally more hygroscopic than Aitken particles but less hygroscopic than the 30 nm particles (nuclei mode).

Comparison of four digestion protocols on the physical characteristics of gastric digesta from cooked couscous using the Human Gastric Simulator.

In vitro digestion is widely employed in food, nutraceutical and pharmaceutical research, and numerous in vitro gastric digestion protocols have been proposed, with a wide range of experimental conditions. Differences in the simulated gastric fluids (pH, mineral content, enzyme type and enzyme activity) of different digestion protocols may alter the results for the digestion of the same meal. This study aimed to investigate how variations in the gastric secretion rate and composition in four in vitro digestion protocols (Infogest Riddet, Infogest Semi-dynamic, UC Davis and United States Pharmacopeia) impacted the physical properties of the emptied gastric digesta. Cooked couscous was used as a model meal and subjected to simulated gastric digestion using a dynamic gastric model, the Human Gastric Simulator (HGS). The digesta were collected from the outlet of the HGS after 15, 30, 60, 90, 120, 150, or 180 min. The gastric emptying of dry matter, pH, rheological properties, and particle size were evaluated. The digestion protocol significantly influenced the solid content and moisture content of the digesta (p < 0.001), particles per gram of dry matter (p < 0.0001), gastric emptying of dry matter (p < 0.003), shear stress at 0.45 s-1 and consistency coefficient (p < 0.0001). The presence of NaHCO3 in the Infogest Riddet and Infogest Semi-dynamic gastric secretions provided an additional buffering effect and increased the digesta pH during gastric digestion. Similarly, the inclusion of mucin in the UC Davis protocol resulted in a higher flow and viscoelastic properties of the emptied digesta. The highest dilution of gastric content in the United States Pharmacopeia (USP) protocol resulted in larger particles emptied from the HGS and the longest gastric emptying half-time of all digestion protocols. These findings provide new insights into the impact of digestion protocols on the digesta properties, which can be beneficial for the design and standardization of in vitro digestion models.

Sediment trap height affects mass, particle size, and biogeochemical composition of material collected in an equatorial coral reef.

Anthropogenic sedimentation is a major contributor to the worldwide decline in coral cover. Resuspension of benthic material can exacerbate the threat to corals, but evidence of vertical sediment gradients is limited. Here, we installed sediment traps at 10, 20, 30, 40, and 50cm above the substrate at three equatorial reef sites for three months and determined the dry mass, particle size, and biogeochemical composition of the material collected. As the trap mouth height increased from 10 to 50cm, dry mass decreased as sediments became finer, poorer in carbonate, and richer in silicate. Despite among-site differences in collected sediment, this vertical gradient was present in all trap arrays, likely driven by resuspension mechanisms on seabed sediments. These results have implications for coral vertical ecology and underline the importance of standardising sediment collection protocols.

Predicting Spray Dried Dispersion Particle Size Via Machine Learning Regression Methods

Spray dried dispersion particle size is a critical quality attribute that impacts bioavailability and manufacturability of the spray drying process and final dosage form. Substantial experimentation has been required to relate formulation and process parameters to particle size with the results limited to a single active pharmaceutical ingredient (API). This is the first study that demonstrates prediction of particle size independent of API for a wide range of formulation and process parameters at pilot and commercial scale. Additionally we developed a strategy with formulation and target particle size as inputs to define a set of “first to try” process parameters. An ensemble machine learning model was created to predict dried particle size across pilot and production scale spray dryers, with prediction errors between −7.7% and 18.6% (25th/75th percentiles) for a hold-out evaluation set. Shapley additive explanations identified how changes in formulation and process parameters drove variations in model predictions of dried particle size and were found to be consistent with mechanistic understanding of the particle formation process. Additionally, an optimization strategy used the predictive model to determine initial estimates for process parameter values that best achieve a target particle size for a provided formulation. The optimization strategy was employed to estimate process parameters in the hold-out evaluation set and to illustrate selection of process parameters during scale-up. The results of this study illustrate how trained regression models can reduce the experimental effort required to create an in-silico design space for new molecules during early-stage process development and subsequent scale-up.

Visualization and Measurement of Swirling Flow of Dry Ice Particles in Cyclone Separator-Sublimator

The dry ice sublimation process of carbon dioxide (CO2) is a unique, environmentally friendly technology that can achieve a temperature of −56 °C or lower, which is a triple point of CO2 in CO2 refrigeration systems. In this study, a cyclone separator-evaporator was proposed to separate dry ice particles in an evaporator. As an initial step before introducing the cyclone separator-evaporator into an actual refrigeration system, a prototype cyclone separator-evaporator was constructed to visualize dry ice particles in a separation chamber. A high-speed camera was used to visualize the non-uniform flow of dry ice particles that repeatedly coalescence and collision in a swirl section. Consequently, the dry ice particle size and the circumferential and axial velocities of dry ice were measured. The results show that the equivalent diameter of the most abundant dry ice particles in the cyclone separation chamber is 2.0 mm. As the inner diameter of the separation section decreases, dry ice particles coalesce and grow from an equivalent diameter of 4 mm to a maximum of 40 mm. In addition, the comparison of the experimental and simulation results shows that the drag force due to CO2 gas flow is dominant in the circumferential velocity of dry ice particles.

Understanding the effect of porosity and pore size distribution on low loading catalyst layers

Stochastic reconstructions, generated using an overlapping sphere algorithm with different particle sizes, were used to understand the role of the catalyst layer (CL) pore size distribution and porosity on the gas transport, local saturation and electrochemical performance of a low loading cathode. Statistical functions were used to characterize the morphology of the CLs and numerical simulations were performed to study the effective transport properties and electrochemical performance under dry and wet conditions. Results show that an increase in pore size increases the dry effective diffusivity but lowers the partially-saturated diffusivity at a given capillary pressure due to higher local saturation in the CL. Under dry conditions, porosity and particle size had negligible effect on the electrochemical performance of low loading CLs despite substantial changes in the ionomer distribution. Electrochemical simulation results at different liquid pressures show that CLs with moderate porosity and small particle size would maximize performance at a given capillary pressure due to lower liquid water accumulation, higher evaporation driven water transport and lower probability of water breakthrough to the diffusion media.

On the evolution of sub- and super-saturated water uptake of secondary organic aerosol in chamber experiments from mixed precursors

Abstract. To better understand the chemical controls of sub- and super-saturated aerosol water uptake, we designed and conducted a series of chamber experiments to investigate the evolution of secondary organic aerosol (SOA) particle physicochemical properties during photo-oxidation of single and mixed biogenic (α-pinene, isoprene) and anthropogenic (o-cresol) volatile organic compounds (VOCs) in the presence of ammonium sulfate seeds. During the 6 h experiments, the cloud condensation nuclei (CCN) activity at super-saturation of water (0.1 %–0.5 %), hygroscopic growth factor at 90 % relative humidity (RH), and non-refractory PM1 chemical composition were recorded concurrently. Attempts to use the hygroscopicity parameter κ to reconcile water uptake ability below and above water saturation from various VOC precursor systems were made, aiming to predict the CCN activity from the sub-saturated hygroscopicity. The thermodynamic model AIOMFAC (aerosol inorganic-organic mixtures functional groups activity coefficients) was used to simulate κ values of model compound mixtures to compare with the observation and to isolate the controlling factors of water uptake at different RHs. The sub- and super-saturated water uptake (in terms of both κHTDMA and κCCN) were mainly controlled by the SOA mass fraction, which depended on the SOA production rate of the precursors, and the SOA composition played a second-order role. For the reconciliation of κHTDMA and κCCN, the κHTDMA/κCCN ratio increased with the SOA mass fraction and this was observed in all investigated single and mixed VOC systems, independent of initial VOC concentrations and sources. For all VOC systems, the mean κHTDMA of aerosol particles was ∼25 % lower than the κCCN at the beginning of the experiments with inorganic seeds. With the increase of condensed SOA on inorganic seed particles throughout the experiments, the discrepancy of κHTDMA and κCCN became weaker (down to ∼0 %) and finally the mean κHTDMA was ∼60 % higher than κCCN on average when the SOA mass fraction approached ∼0.8. As indicated by AIOMFAC model simulations, non-ideality alone cannot fully explain the κ discrepancy at high SOA mass fraction (0.8). A good agreement in κCCN between model and observation was achieved by doubling the molecular weight of the model compounds or by reducing the dry particle size in the CCN counter. This indicates that the evaporation of semi-volatile organics in the CCN counter together with non-ideality could have led to the observed κ discrepancy. As a result, the predicted CCN number concentrations from the κHTDMA and particle number size distribution were ∼10 % lower than CCN counter measurement on average at the beginning, and further even turned to an overestimation of ∼20 % on average when the SOA mass fraction was ∼0.8. This chemical composition-dependent performances of the κ-Köhler approach on CCN prediction can introduce a variable uncertainty in predicting cloud droplet numbers from the sub-saturated water uptake, the influence of which on models still needs to be investigated.

Soil–water characteristic curves and hydraulic conductivity of Gaomiaozi bentonite pellet-contained materials

The bentonite pellet-contained material (PCM) is a desired joint sealer for high-level radioactive waste repositories. During the operation of the repository, however, the PCM is unsaturated for most of the period. The water retention capacity and permeability of PCM can thus directly affect the bentonite buffer barrier seepage, nuclide migration, and joint healing. Moreover, the performance of PCM can be strongly influenced by the particle size of bentonite pellets and dry density. In this work, the pressure plate method and vapor equilibrium technique were both utilized to test the soil–water characteristic curves (SWCCs) of the PCMs with varying particle sizes and dry densities. The unsaturated hydraulic conductivity of the PCMs was then predicted by combining the SWCC model and saturated hydraulic conductivity. The results showed that in the low suction range (20–1150 kPa), the dry density and particle size are anti-correlated with the water content. In the high suction range (4200–309,000 kPa), the SWCC is almost insensitive to the variation of dry density and particle size. The Gardner model is suitable for describing the SWCC of PCM. In addition, the hydraulic conductivity of the PCM increases with the rise in particle size, while it decreases as the dry density grows. Finally, the influence mechanism of the SWCC and hydraulic conductivity was further discussed based on the scanning electron microscopy images and pore size distribution curves.

Mechanical characteristics of compressed earth blocks, compressed stabilized earth blocks and stabilized adobe bricks with cement in the town of Ngaoundere - Cameroon

The aim of this study is to examine the effects of cement stabilization on the mechanical stress of compressed stabilized earth blocks (CSEBs) and adobe stabilized earth bricks (ASEBs). Hence, this work is based on an experimental study carried out in order to determine the geotechnical properties of the samples soil, namely, the dry particle size analysis after washing, the particle size distribution by sedimentometry, Atterberg limits, and the preparation of specimens with different levels of cement proportions. Moreover, single compression and three-point bending compression out on specimens measuring 4x4x4cm3 and 4x4x16cm3 respectively. The findings indicate that dosing with 8% cement results in a clear increase in compression stress of approximately 25.55% for CSEBs compared to the reference set at 0% and 22.85% for ASEBs. On the other hand, for a dosage of 4%, we observe a slight increase in stress by simple compression of around 3.26% for CSEBs and 3.14% for ASEBs. For three-point bending compression for a cement dosage of 8%, there is also an increase in stress of about 25% for the CSEBs compared to the reference taken at 0% and 23.02% for the ASEBs.

STUDY ON THE INFLUENCE OF DRY DENSITY AND PARTICLE SIZE FRACTAL DISTRIBUTION ON THE RADON CONTROL PERFORMANCE OF OVERLYING SOIL IN URANIUM TAILINGS POND.

In order to explore the influence of dry density and particle size fractal distribution on the radon control performance of overlying soil in uranium tailings pond, overlying soil samples with different particle size fractal dimension and dry density were prepared for radon exhalation experiments. According to the principle of radon generation and diffusion, a set of radon measuring device was designed independently. In addition, the radon concentration on the surface of different overlying soil layers was measured by local static method, and the radon exhalation rate was further calculated. The relationship between radon exhalation law, dry density and fractal dimension of overlying soil was studied by correlation analysis method. Furthermore, a piecewise linear function between radon exhalation rate, dry density and fractal dimension was constructed. Then, the average value of the experimental data was compared with the calculated results. Results show that: at the same dry density and different fractal dimension, the radon exhalation rate decreased with the increase of fractal dimension. When the fractal dimension increased to a certain value, the radon exhalation rate tended to be stable. At the same fractal dimension and different dry density, the radon exhalation rate decreased with the increase of dry density. The calculated results of piecewise linear function were relatively close to the experimental data, which verified the practicability of the formula.

Effects of Dry Heat Treatment and Milling on Sorghum Chemical Composition, Functional and Molecular Characteristics

This study aimed to highlight the effects of grains dry heat treatment, flour particle size and variety on sorghum flour nutritional, functional, and molecular characteristics. The results obtained showed that dry heat treatment led to fat, fiber and water absorption capacity increase, while the moisture, protein, ash, water retention capacity, solubility index, foaming capacity, and FT-IR absorption bands characteristic to phytic acids decreased with temperature applied raised. Particle size reduction determined lower protein, solubility index, and emulsifying activity and higher fat content, oil absorption capacity, swelling power, and foaming capacity. White sorghum flour fractions presented lower protein content, except when they were treated at 140 °C, lower carbohydrates and fibers and higher fat content compared to those made of red sorghum. Moderate significant correlations (p &lt; 0.05) were observed between some of the functional properties and proximate composition of flours. Thus, both dry heat treatment conditions and particle size exerted significant influences of sorghum flour chemical and functional properties. These results showed the importance of particle size and dry heat treatment on sorghum flours functionality, being helpful for further optimizations and choices for bakery products use.

Characterization of the Relationship between the Loess Moisture and Image Grayscale Value.

This paper presents a model for estimating the moisture of loess from an image grayscale value. A series of well-controlled air-dry tests were performed on saturated Malan loess, and the moisture content of the loess sample during the desiccation process was automatically recorded while the soil images were continually captured using a photogrammetric device equipped with a CMOS image sensor. By converting the red, green, and blue (RGB) image into a grayscale one, the relationship between the water content and grayscale value, referred to as the water content–gray value characteristic curve (WGCC), was obtained; the impacts of dry density, particle size distribution, and illuminance on WGCC were investigated. It is shown that the grayscale value increases as the water content decreases; based on the rate of increase of grayscale value, the WGCC can be segmented into three stages: slow-rise, rapid-rise, and asymptotically stable stages. The influences that dry density and particle size distribution have on WGCC are dependent on light reflection and transmission, and this dependence is closely related to soil water types and their relative proportion. Besides, the WGCC for a given soil sample is unique if normalized with illuminance. The mechanism behind the three stages of WGCC is discussed in terms of visible light reflection. A mathematical model was proposed to describe WGCC, and the physical meaning of the model parameters was interpreted. The proposed model is validated independently using another six different types of loess samples and is shown to match well the experimental data. The results of this study can provide a reference for the development of non-contact soil moisture monitoring methods as well as relevant sensors and instruments.

Aerosol Activation in Radiation Fog at the Atmospheric Radiation Program Southern Great Plains Site

AbstractEnvironmental supersaturation is a key parameter in the formation of fog and clouds, yet it cannot be measured directly and must be inferred. Calculating the ambient supersaturation in fog requires knowledge of the aerosol hygroscopicity as well as particle size distribution, and relatively few values have been reported in the literature. Here we use κ‐Köhler theory to derive aerosol activation properties based on particle hygroscopicity and dry particle size distributions, and then estimate the effective peak supersaturation during eight cases of radiative fog at the Southern Great Plains site in rural north‐central Oklahoma, USA. The mean hygroscopicity parameter κ of particles likely to act as cloud condensation nuclei varied from 0.14 to 0.43. Ambient effective peak supersaturation during the fog episodes was between 0.01%–0.07%, with most values below 0.04%. The minimum 50% dry activation diameter generally ranged between 300–400 nm with little activation of particles with diameters below 300 nm.

Experimental Investigation of Particle Size Degradation and Plugging Efficiency of Three Granular Lost Circulation Materials

This work delineates a comprehensive study of one of the main problems that contributes towards nonproductive time (NPT) in a drilling operation, which is lost circulation. The focus of this study was to investigate the performance of walnut, graphite, and marble, which are three widely used and industry-available granular lost circulation materials (LCMs). Additionally, the study aimed to establish a particle size selection guideline for better operational performance and plugging efficiency. Four water-based carrier fluid systems (water–bentonite mix, water–polymer mix, and two polymer–salt systems) were tested with the LCMs in this study. Dry and wet particle size degradation studies were conducted on all the LCMs with the different carrier fluid systems to study their compatibility and efficiency. The effect of the carrier fluid type was proven to be significant only on marble particles size degradation; walnut and graphite were not affected by the carrier fluids and showed consistent size degradation performance with all fluids. The results of this work led to newly developed particle size selection guidelines to enhance plugging efficiency—guidelines that are custom-made for each material by taking into consideration the rate of the degradation and type of material and by correlating the findings with fracture width. Applying this method of investigation to the current lost circulation management practice can help resolve many lost circulation incidents by effectively and efficiently selecting the appropriate LCM.

Interaction of cesium bound fission product compounds (CsI and CsOH) with abundant inorganic compounds of atmosphere: Effect on hygroscopic growth properties

Cesium compounds if present in atmosphere, can affect human health as well as the ecosystem due to their highly hazardous nature. Interaction of cesium compounds with abundantly available atmospheric salts can modify the hygroscopic behavior in sub-saturation relative humidity (RH) domain. Any marked modification in growth factor (GF) for the mixed particle state in comparison to the single particles ultimately affects the settling rates and hence the deposition flux. This work studies the hygroscopic behavior of two important cesium bound fission product aerosols (CsI, CsOH) internally mixed with some common atmospheric particles viz. NaCl,(NH4)2SO4 and NaNO3 for a fixed dry particle size of 100 nm. Experimental measurements, performed with Hygroscopic tandem differential mobility analyzer in the range of 20–94% RH, have been compared with the predictions made from Zdanovskii-Stokes-Robinson (ZSR) approach. Apart from the single/pure particle state for the constituents (i.e. mixing ratios 1:0 and 0:1), three other mixing ratios 1:4, 1:1 and 4:1 have been considered. The results show that the GF vs RH pattern for mixed particles is different from that for single CsI and CsOH particles. The intrinsic water uptake behavior for these cesium compounds was found to be perturbed for some of the chosen combinations as well. Deliquescent transition for the mixed particles was observed at lower RH compared to the single electrolytes. Relative differences noticeable for the chosen mixing ratios could be related to the available fractions in the mixed state. Overall, ZSR method was found to be capturing the trend of increasing GFs with increasing RH. Terminal gravitational settling velocities calculated from the measured GFs were also found to be different for single and mixed particles. The relative difference was significant for some combinations and test conditions. Any modification in settling velocity ultimately impacts the deposition flux estimations. Hence neglecting the presence of atmospheric salts affects the accuracy of the source term estimates for a postulated nuclear reactor accident scenario.

Soil-water characteristics of weathered crust elution-deposited rare earth ores

The permeability of the weathered crust elution-deposited rare earth ores directly affects the efficiency of in-situ leaching. The soil-water characteristic curve (SWCC) is an important constitutive relation for calculating the permeability of ore body, which is related to many factors. Soil-water characteristic tests of rare earth ore samples considering different factors were carried out by using the pressure plate instrument. Effects of dry density, particle size and solution leaching on water holding behavior and the mechanism were investigated. The experimental observations indicate that with the decrease of dry density, the pore ratio increases gradually, and the saturated water content increases. Under the same matric suction, the water content decreases gradually with the increase of particle size, thus decreasing water holding capacity of ore accordingly. In the same water content, matric suction is inversely proportional to particle size. Under the same matric suction, the water content of ore samples after leaching is less than that of the ore samples before leaching, indicating that solution leaching can decrease water holding capacity of ore.