Coarse Ones Research Articles

Dense liquid flotation: Can coarse particle flotation performance be enhanced by controlling fluid density?

• Bubble-load is optimized in bubble-particles aggregates of fine particles compared to coarser ones. • Coarser particles simulate the detachment behavior of finer particles at increased fluid SGs. • Increased critical detachment amplitudes at increased fluid SGs translate to better flotation performance for coarse particles in terms of recovery, rate, and maximum floatable size. • Increasing fluid SG beyond a limit increases the likelihood of detachment in the froth phase. • Particle weight in fluid is the major detachment force, and the effect of cell turbulence on coarse particle flotation performance is largely dependent on it. In this work, we investigate the influence of fluid density on bubble-particle detachment and coarse particle flotation performance. Detachment studies were carried out using an electro-acoustic apparatus in a dense liquid environment using a lithium heteropolytungstate (LST) mixture with subsequent flotation studies carried out in a micro flotation cell at varying fluid densities. Our results indicate that bubble load was inherently limited by particle surface area and weak particle–particle interactions at coarser sizes. Coarser particles tend to follow the detachment behavior of relatively finer particles at increased fluid density. We also found that flotation performance in terms of recovery, rate, and maximum floatable size can be enhanced by controlling fluid density within a stated limit beyond which detachment in the froth phase causes overall performance to drop.

Optimization on fishing net porosity of twin pontoon floating breakwater in waves

Chaotic process in wave passing through pores on the attached fishing net between twin pontoons of floating breakwater (TPFB) may lead to several severe problems relating to the hydrodynamic performance of such coastal structure. In presence of relatively fine pores, the wave transmission coefficient (Kt) tends to diminish while the reflection coefficient (Kr) will likely increase, or vice versa for coarse ones. The circumstance requires a complete design optimization study into obtaining an optimum porosity. This paper presents optimization on the fishing net porosity (n) of TPFB using artificial intelligence (AI) model. Here, a multi-objective evolutionary algorithm with various genetic parameters is proposed to search for optimum n ratio through primarily minimizing transmission (Kt) and reflection coefficients (Kr) while maximizing energy dissipation coefficient (Kd). In addition, a computational fluid dynamic (CFD) programme is developed using an extended Reynolds Average Navier-Stokes (RANS) solver for a solid-permeable obstacle. Several parameters such as wavelengths and porosity ratios including a set of optimization criteria, have been taken into account in the simulation, where the optimum solution is then selected from various populations. Meanwhile, the optimum result will be qualitatively evaluated, in which it is visualized by the characteristic patterns of induced energy dissipation. The results revealed that the optimization algorithm is effectively capable of determining global trade-offs between Kt, Kr, and Kd. As compared to the existing model, Kt and Kr decrease to less than 0.85 and 0.42 respectively, whereas Kd was increased up to 0.34 resulting in optimum hydrodynamics of TPFB indicated by further enhancement in the rate of energy dissipation across TPFB entanglement. For validation, the numerical model can fairly simulate well on the hydrodynamics of structure.

Size-Segregated Elemental Profile and Associated Heath Risk Assessment of Road Dust along Major Traffic Corridors in Kolkata Mega City

Particle size distribution (PSD) of road dust has significant repercussions on atmospheric pollution by road dust resuspension. The PSD of road dust at a few major commercial, traffic, and residential sites in Kolkata mega city was analyzed in the size range of <28–2000 µm. Predominance of the coarse size range (212–600 µm followed by 106–212 µm) was observed. In size-segregated road dust, Fe (4.02–31.2 g kg−1) dominated other elements and was followed by Mg (2.13–10.9 g kg−1), Mn (79.2–601 mg kg−1), Li (395.8–506.8 mg kg−1), and others. Fine particles (<28 μm) had higher elemental concentrations than coarser ones. Cd and Li showed the highest degree of enrichment compared to the Earth’s crust, but only Cd posed significant ecological risk due to its high ecological toxicity. Individual elements did not post significant non-cancer health risks, except for Li in children. However, the cumulative non-cancer risk from all toxic elements for children was almost four times higher than the acceptable level. Lifetime exposure to carcinogenic elements at the current level may pose 5 to 6 times higher cancer risk in the adult population than the acceptable risk of one in a million.

Effect of beam oscillating frequency on the microstructure and mechanical properties of dissimilar laser welding of AA2060 and AA6061 alloy

Welding of dissimilar aluminum alloys is gaining an attention in academic and industrial communities because of wide spread industrial application. In this study, the dissimilar laser welding of AA2060-T8 and AA6061-T6 thin slabs is conducted using circular mode oscillation welding with amplitude of 0.5 mm and different oscillation frequencies. With the aid of numerical simulation, optical microscopy (OM) and electron backscatter diffraction (EBSD), the microstructure evolution mechanism of the obtained welded joints and their correlations with mechanical properties and failure modes are systematically studied. In comparison to rectilinear weldment, the mechanical properties of welded joint could be significantly improved via beam oscillation welding, with the maximum of tensile strength reaching to 277 MPa at oscillation frequency of 30 HZ, (about 89% of the AA6061-T6 sheets) and the elongation improving by about 65% compared to the sample with non-oscillation welding. Higher frequency dramatically decreases the EQZ area at AA2060 side, and sharply expenses the equiaxed grain zone at central area of welded joints. In EBSD analyses, the orientations of refined columnar grains present randomization tendency, and the coarse ones show solidification texture component with <100> parallel to growth direction. The relationships of these microstructural variations and fracture modes are analyzed. In addition, to fully understand the formation mechanisms of welded microstructures, thermal simulation is conducted in this paper. From results of the thermal simulations, it can be observed that the 30 HZ oscillating weldment has a similar cooling rate with the one of non-oscillation mode, coupled with the stirring effect of beam oscillation, resulting in a refinement of the solidified microstructure and relatively higher mechanical properties.

Negative impact of humidity on the flowability of steel powders

Atmospheric humidity is introduced into powders during handling, transportation, and storage. High moisture content can increase cohesive forces between particles and make it difficult to spread a powder into thin layers in powder bed processes or to fill a mold in processes such as press-and-sinter. Furthermore, water can cause porosity and uptake of oxygen in the final component, damaging its mechanical properties. In this study, a Freeman FT4 powder rheometer was placed inside a climate chamber. Both flowability and shear tests were performed on four steel powders under a range of humidity and temperatures. Basic flowability energy and specific energy were both found to increase significantly with humidity (typically increase by 50% for 80% of relative humidity compared to dry conditions) and were insensitive to temperature change (10–30 °C). Conversely, the behavior of the powders under shear was neither sensitive to relative humidity nor temperature. Measurements of moisture content revealed that finer powders contained more moisture than coarser ones, but the moisture content was not correlated with humidity, probably due to shortcomings with the measurement method. This knowledge can be used to optimize powder processing conditions.

Impact of deforestation on radiative and thermal regimes of the territory of Ukraine on the base of global climate models data

This paper is dedicated to the influence of partial deforestation with using global retrospective modelling data from The Land Use Model Intercomparison Project (LUMIP) for the territory of Ukraine. This experiment aims to global gradual deforestation and has two phases. The first phase, defined as the pre-industrial period (1850—1899) with constant unchangeable anthropogenic impact. For this period deforestation modelled with further replacement with grass cover with a linear trend 400000 km2/yr or 20 million km2 per 50 years in general. The second phase is next 30 years with no significant changes in forest cover (1900—1929). For conducting this research the data of several global climate models were applied. The results of analysis have demonstrated that a partial deforestation with grass substitution influences the surface reflectivity or albedo and redistribution of shortwave radiative fluxes. In turn, it provokes changes in thermal regime. It was found that the most significant changes in surface reflectivity and the strongest correlation coefficients between albedo and deforestation are in the winter season due to the presence of snow cover. As a result, statistical significant increase of albedo is with maximum values up to 24 %/50 years in some grids in winter. Then in the summer season maximal changes are up to 2.7 %/50 years due to small differences between forest and grass albedos. As a consequence, changes in albedo cause changes in surface and air temperature regimes. Strong dependencies were found in winter between changes in albedo and temperatures with maximum temperature decrease 2.5…2.0 %/50 years. In warm season correlations are weaker in comparison to cold season, but nevertheless, temperatures decrease also take place with maximum values 2.0…1.5 %/50 years. The analysis between deforestation and daily air temperature range has shown that particularly in winter season there is an increase of 0.5...1.5 %/50 years, whereas such tendency is not observed in warm season. Calculations of year air temperature range demonstrated controversial results among climate models, as follows it is hard to make a conclusion about the contribution of forest cover reduction to changes in this index. It was revealed, that global climate models with higher resolution are more sensitive to changes in albedo and, as a consequence to other characteristics than models with coarse ones. It should be noticed that obtained results concern pre-industrial period with minimal anthropogenic impact, when observed a stable snow cover in winter in Ukraine. In the current climate change with significant warming and reduction of snow season duration deforestation can have opposite effects on radiative and thermal regimes that require further studying.

Densification behavior of microwave hybrid sintered Al2O3 bimodal powder mixtures and comparison with 3D modeling and simulation

In this study, slip casting and microwave hybrid sintering of Al2O3 bimodal powder mixtures were conducted to observe the effect on packing factor and densification behavior of different compositions. The powder mixtures contained up to 50 vol% fine particles. It was found that the green density increased remarkably with the addition of fine particles into coarse ones, and the composition having 30 vol% fine particles had the highest relative density of 72.7%. A similar behavior was also observed in sintered samples, where the sintered densities were also higher for bimodal compositions. Moreover, 3D modeling of the system was carried out, and the sintering behavior was simulated and compared with the experimental data. It was shown that with the same relative green density of 50% solid volume for all samples, the composition with 40 vol% fine particles exhibited the highest relative sintered density of 92.1%. The sintering behavior was also predicted for highly dense modeled structures, which could not be obtained experimentally, and pore analysis was performed. It was observed that the closed porosity increased with the addition of fine particles, while the pore size distribution significantly reduced, where 81.4 vol% pores had pore sizes of only up to 0.28 μm.

Polycyclic aromatic hydrocarbons in airborne particulate matter samples from Hanoi, Vietnam: Particle size distribution, aryl hydrocarbon ligand receptor activity, and implication for cancer risk assessment

Concentrations and profiles of unsubstituted and methylated polycyclic aromatic hydrocarbons (PAHs and Me-PAHs) were analyzed in airborne particulate matter (PM) samples collected from high-traffic roads in Hanoi urban area. Levels of PAHs and Me-PAHs ranged from 210 to 660 (average 420) ng/m3 in total PM, and these pollutants were mainly associated with fine particles (PM2.5) rather than coarser ones (PM > 10 and PM10). Proportions of high-molecular-weight compounds (i.e., 5- and 6-ring) increased with decreasing particle size. Benzo[b+k]fluoranthene, indeno[1,2,3-cd]pyrene, and benzo[ghi]perylene were the most predominant compounds in the PM2.5 samples. In all the samples, Me-PAHs were less abundant than unsubstituted PAHs. The PAH-CALUX assays were applied to evaluate aryl hydrocarbon receptor (AhR) ligand activities in crude extracts and different fractions from the PM samples. Benzo[a]pyrene equivalents (BaP-EQs) derived by the PAH-CALUX assays for low polar fractions (mainly PAHs and Me-PAHs) ranged from 300 to 840 ng/m3, which were more consistent with theoretical values derived by using PAH-CALUX relative potencies (270–710 ng/m3) rather than conventional toxic equivalency factor-based values (22–69 ng/m3). Concentrations of PAHs and Me-PAHs highly correlated with bioassay-derived BaP-EQs. AhR-mediated activities of more polar compounds and interaction effects between PAH-related compounds were observed. By using PAH-CALUX BaP-EQs, the ILCR values ranged from 1.0 × 10−4 to 2.8 × 10−4 for adults and from 6.4 × 10−5 to 1.8 × 10−4 for children. Underestimation of cancer risk can be eliminated by using effect-directed method (e.g., PAH-CALUX) rather than chemical-specific approach.

Release of particles and metals into seawater following sediment resuspension of a coastal mine tailings disposal off Portmán Bay, Southern Spain.

Portmán Bay in Southern Spain is one of the most extreme cases in Europe of anthropogenic impact on the marine ecosystem by the disposal of mine tailings resulting from the processing of sulphide ores. First, the composition and extent of the surficial deposit were investigated from geochemical and metal analysis on high spatial density of sediment samples. Then, a disturbance experiment was conducted in the coastal area off Portmán Bay in order to investigate the potential impact of mining activities on marine ecosystems. Two research vessels were used for that experiment, one performing as a trawler resuspending bottom sediments while the other monitor the behaviour of turbid plumes thus generated and the evolution of their characteristics through time by using a range of acoustic and optical tools together with water and bottom sediment sampling for biogeochemical and metal analyses. The surficial part of the submarine extension of the mine tailings deposit is highly concentrated in As, Cd, Pb, Fe and Zn with peak concentrations adjacent to the present coastline, from where they decrease seawards before reaching average values for the Mediterranean Sea around 50-m water depth. The artificially triggered resuspension of the surface layer of the deposit led to the formation of resuspension plume about 100 m in width and up to 6 m in height. Resuspended plume was composed of fine particles which rapidly aggregated into flocs of 100 μm. While the biggest particles settled rapidly, the finest fraction remained in suspension during at least 3 h. Resuspended sediment and metal concentrations in particles remained at relatively high levels throughout the experiments following triggering. Fe, Pb, and As concentrations in resuspended particles showed a continuous increase while trawling before decreasing in parallel with the settling down of the resuspended sediments. Those metals have higher affinity with fine particles than with coarse ones, so that while the coarsest fraction from sediment plumes settled first, the finest fraction remained in suspension thus increasing the metals/sediments concentration ratio. On the other hand, Cd and Zn concentrations in suspended particles did not change significantly over time, which is thought to be caused by the fast dissolution of such metals in seawater. Beyond waste dumping itself, the observed increase in some metals in marine particulate material could have a significant impact on the adjacent coastal ecosystems due to their toxicity above certain thresholds. The consequences of the resuspension experiment here presented can be extrapolated to the impact of seafloor mining activities leading to the resuspension of metal-rich particle plumes into the water column. The experimental set-up presented here may be further explored for investigating metal behaviour during seafloor mining activities.

Particle Size Effects on Selectivity in Confined Bed Comminution

Confined bed comminution in high-pressure grinding rollers (HPGRs) and vertical roller mills (VRMs) was previously used preferably for grinding comparably homogeneous materials such as coal or clinker. Meanwhile, it started to complement or even replace tumbling mills in ore beneficiation with ore and gangue particles of rather different breakage behaviors. The selectivity in the comminution of a mixture of particles with different strengths but similar particle size distribution (PSD) of the constituents in a particle bed was investigated earlier. The strength of a material is, however, also a function of particle size. Finer particles tend to be more competent than coarser ones of the same material. In industrial ore processing using confined bed comminution, this effect cannot be neglected but even be exploited to increase efficiency. This paper presents research results on this topic based on experimental investigations with model materials and with natural particles, which were stressed in a piston–die press. It appeared that the comminution result substantially depends on the material characteristics, the composition of the mixture and the PSD of the constituents. Conclusions will be drawn for the future applications of selective comminution in mineral processing.

Knowledge-based classification of fine-grained immune cell types in single-cell RNA-Seq data.

Single-cell RNA sequencing (scRNA-Seq) is an emerging strategy for characterizing immune cell populations. Compared to flow or mass cytometry, scRNA-Seq could potentially identify cell types and activation states that lack precise cell surface markers. However, scRNA-Seq is currently limited due to the need to manually classify each immune cell from its transcriptional profile. While recently developed algorithms accurately annotate coarse cell types (e.g. T cells versus macrophages), making fine distinctions (e.g. CD8+ effector memory T cells) remains a difficult challenge. To address this, we developed a machine learning classifier called ImmClassifier that leverages a hierarchical ontology of cell type. We demonstrate that its predictions are highly concordant with flow-based markers from CITE-seq and outperforms other tools (+15% recall, +14% precision) in distinguishing fine-grained cell types with comparable performance on coarse ones. Thus, ImmClassifier can be used to explore more deeply the heterogeneity of the immune system in scRNA-Seq experiments.

Integrated modeling methodology for ash agglomeration in poly-disperse fluidized beds using particle population framework

This paper discusses a unique agglomeration modeling methodology developed based on binary collisions to combine the effects of heterogeneity in ash chemistry and granular physics. A simple population balance is defined to find changes in the particle size distribution (PSD) of a fluidized bed. Thermodynamic equilibrium calculations and a computational fluid dynamics (CFD) code, are used to obtain hydrodynamic parameters. A method to calculate and use a distribution of collision frequencies in fluidized beds, corresponding to a poly-disperse particle size distribution, was developed in order to incorporate the particle level heterogeneities. A distribution of collision frequencies obtained for poly-dispersed particles showed a three orders of magnitude higher collision frequency amongst the smaller particles than the coarser ones, at the initiation of agglomeration. Ash agglomeration occurred when the slag amount (binder) was less than 10 wt% at temperatures <850 °C for Pittsburgh No. 8 coal.

Balancing the strength and ductility of Mg-6Zn-0.2Ca alloy via sub-rapid solidification combined with hard-plate rolling

In this study, we successfully prepared a Mg-6Zn-0.2Ca alloy by utilizing sub-rapid solidification (SRS) combined with hard-plate rolling (HPR), whose elongation-to-failure increases from ∼17 % to ∼23 % without sacrificing tensile strength (∼290 MPa) compared with its counterpart processed via conventional solidification (CS) followed by HPR. Notably, both samples feature a similar refined grain structure with an average grain size of ∼2.1 and ∼2.5 μm, respectively. However, the high cooling rate of ∼150 K/s introduced by SRS modified both the size and morphology of Ca2Mg6Zn3 eutectic phase in comparison to those coarse ones under CS condition. By subsequent HPR, the Ca2Mg6Zn3 phase was further refined and dispersed uniformly by severe fragmentation. Specially, the achieved supersaturation containing excessive Ca solute atoms due to high cooling rate was maintained in the SRS-HPR condition. The mechanisms that govern the high ductility of the SRS-HPR sample could be ascribed to following reasons. First, refined Ca2Mg6Zn3 eutectic phase could effectively alleviate or avoid the crack initiation. Furthermore, excessive Ca solute atoms in α-Mg matrix result in the yield point phenomenon and enhanced strain-hardening ability during tension. The findings proposed a short-processed strategy towards superior performance of Mg-6Zn-0.2Ca alloy for industrial applications.

Performance of rubberized concrete exposed to chloride solution and continuous wet–dry cycle

Worldwide, the accumulation of discarded waste tire rubbers remains one of the major environmental concerns unless recycled in an eco-friendly approach. One of the sustainable solutions is to recycle the waste tire rubber as a partial replacement of natural aggregates in concrete. The main aim of this study was to investigate the durability of rubberized concrete (RuC) with different amounts (0–30%) of rubber aggregate (RA) at two most practical and common exposure conditions. The main investigating parameters were the rubber particle size, replacement type, replacement amount, and exposure conditions. To evaluate the performance of RuC, the slump value, compressive strength, splitting tensile strength, chloride ion penetration, water absorption, strength loss at different exposure conditions were evaluated. The addition of RA causes a reduction in strength due to the less adhesion of RA and cement paste compared with the control mix. However, finer sized rubber particles show better adhesion and develop higher strength than coarser ones. Consequently, the durability under continuous wet–dry cycles and chloride ion solution was much better for finer RA incorporated concrete. With the increasing content and particle size of RA, the porosity of RuC increased, thus the chloride ion penetration was maximum for 30% replacement level. Therefore, to develop sustainable RuC without any considerable reduction in mechanical and durability properties, the finer particle sized RA is suitable up to an optimum level (< 30%).

XDose: toward online cross-validation of experimental and computational X-ray dose estimation

PurposeAs the spectrum of X-ray procedures has increased both for diagnostic and for interventional cases, more attention is paid to X-ray dose management. While the medical benefit to the patient outweighs the risk of radiation injuries in almost all cases, reproducible studies on organ dose values help to plan preventive measures helping both patient as well as staff. Dose studies are either carried out retrospectively, experimentally using anthropomorphic phantoms, or computationally. When performed experimentally, it is helpful to combine them with simulations validating the measurements. In this paper, we show how such a dose simulation method, carried out together with actual X-ray experiments, can be realized to obtain reliable organ dose values efficiently.MethodsA Monte Carlo simulation technique was developed combining down-sampling and super-resolution techniques for accelerated processing accompanying X-ray dose measurements. The target volume is down-sampled using the statistical mode first. The estimated dose distribution is then up-sampled using guided filtering and the high-resolution target volume as guidance image. Second, we present a comparison of dose estimates calculated with our Monte Carlo code experimentally obtained values for an anthropomorphic phantom using metal oxide semiconductor field effect transistor dosimeters.ResultsWe reconstructed high-resolution dose distributions from coarse ones (down-sampling factor 2 to 16) with error rates ranging from 1.62 % to 4.91 %. Using down-sampled target volumes further reduced the computation time by 30 % to 60 %. Comparison of measured results to simulated dose values demonstrated high agreement with an average percentage error of under 10 % for all measurement points.ConclusionsOur results indicate that Monte Carlo methods can be accelerated hardware-independently and still yield reliable results. This facilitates empirical dose studies that make use of online Monte Carlo simulations to easily cross-validate dose estimates on-site.

Displacement Estimation in Ultrasound Elastography Using Pyramidal Convolutional Neural Network.

In this article, two novel deep learning methods are proposed for displacement estimation in ultrasound elastography (USE). Although convolutional neural networks (CNNs) have been very successful for displacement estimation in computer vision, they have been rarely used for USE. One of the main limitations is that the radio frequency (RF) ultrasound data, which is crucial for precise displacement estimation, has vastly different frequency characteristics compared with images in computer vision. Top-rank CNN methods used in computer vision applications are mostly based on a multilevel strategy, which estimates finer resolution based on coarser ones. This strategy does not work well for RF data due to its large high-frequency content. To mitigate the problem, we propose modified pyramid warping and cost volume network (MPWC-Net) and RFMPWC-Net, both based on PWC-Net, to exploit information in RF data by employing two different strategies. We obtained promising results using networks trained only on computer vision images. In the next step, we constructed a large ultrasound simulation database and proposed a new loss function to fine-tune the network to improve its performance. The proposed networks and well-known optical flow networks as well as state-of-the-art elastography methods are evaluated using simulation, phantom, and in vivo data. Our two proposed networks substantially outperform current deep learning methods in terms of contrast-to-noise ratio (CNR) and strain ratio (SR). Also, the proposed methods perform similar to the state-of-the-art elastography methods in terms of CNR and have better SR by substantially reducing the underestimation bias.

Evaluating the Effects of Watershed Subdivision on Hydrological Simulation by Swat Model in an Arctic Watershed

The hydrological model SWAT is a state-of-the-art tool for environmental and water resources management. Like other semi-distributed models, the whole river basin in the SWAT model is delineated into smaller sub-basins prior to conducting the simulation. Watershed delineation is an importance step since it could potentially influence the modelling results. The present study aimed to conducte an investigation of the effects of watershed delineation schemes on hydrological simulation in an Arctic watershed Målselv, north of Norway. Four delineation schemes were set up with different threshold drainage area (TDA) from fine to coarse including 100 ha, 2,000 ha, 5,000 ha and 10,000 ha. The model was run on monthly time step from 1979-2012. The results showed higher variation of average annual precipitation and runoff especially in the upstream sections of the watershed by the fine TDA schemes compared to the coarse ones. The average monthly precipitation and runoff slightly increased from the finest TDA scheme to the coarsest scheme. All TDA schemes reproduced the observed tendency of the average monthly and annual streamflow although the peak flow was over and under estimated at different hydro-gauging stations. The higher value of estimated streamflow was found at the coarsest scheme.

Diagnostics and correction of dental pathology in rodents and lagomorphs

The article presents the different types of abnormal bite found in rodents and lagomorphs. Methods of diagnosis, treatment and prognosis are considered. Some malocclusions are curable, while others can only be controlled in the course of life through regular examination by a veterinary doctor and periodic correction. The need to conduct a complete examination of the oral cavity and find the cause of the disease is emphasized, since this will seriously affect the prognosis. When establishing a diagnosis, it is necessary to obtain information about the animal from the owner and conduct a thorough clinical examination of all patients, and, if necessary, using a radiology examination. Animals suffering from systemic diseases require special attention, and in severe conditions, life-threatening should urgently respond to treatment. Therapeutic measures for this pathology provide for dental correction, including the elimination of problems associated with excessive tooth growth, consists in filing the hooks and revising the commissure. Sometimes teeth affected by caries must be removed. All procedures are performed strictly under general anesthesia.&#x0D; The main reason for the occurrence of such diseases is the inheritance of an incorrect configuration of the bones of the skull and teeth (a genetic defect in the jaw apparatus). In recent years, as a result of the low level of breeding work, the number of such animals has increased in several cases. However, there are a number of other reasons: improper feeding (an excess of succulent feed in the diet and a lack of coarse ones), a lack of ascorbic acid and an excess of selenium; other metabolic disorders; violations of the density of dental tissues due to errors in feeding (violation of the exchange of calcium, phosphorus and vitamin D); trauma in the head area; diseases of the temporomandibular joint; tumors; refusal to eat in the presence of other diseases accompanied by pain and discomfort for the animal.

McrtFOAM: A mesh-agglomeration Monte Carlo ray-tracing solver for radiative transfer in gray semitransparent solids

Monte Carlo ray-tracing method has become a promising technique for solving radiative transfer. However, large memory footprint or long CPU time hampers its further utilization. In this work, a Monte Carlo ray-tracing method radiation solver called mcrtFOAM is developed in the framework of open source CFD toolbox OpenFOAM. The radiative source term is calculated based on the radiation distribution factor to avoid repeated ray tracing. In addition, a mesh-agglomeration technique is used to overcome the problem of memory catastrophe for storing a huge radiation distribution factor matrix caused by a large number of mesh elements. The key principle is to agglomerate the refined mesh elements to the coarse ones, and the calculation of radiation distribution factor as well as radiative source term is carried out in the coarse mesh, while the procedure of ray tracing as well as solving the heat conduction is performed in the refined mesh. After validation of the algorithm code within a cubic enclosure, a coupled conductive–radiative heat transfer problem within a cylindrical enclosure filled with gray semitransparent solids is also tested. To test the present solver in realistic industrial systems, a coupled conductive–radiative heat transfer within a tomographic porous structure with gray surfaces is further investigated. All results are compared with previous studies and the solutions by the Finite Volume Discrete Ordinate Method (FVDOM) in OpenFOAM, and they all show great satisfaction. When the mcrtFOAM solver is used for solving the radiative transfer equation, it is found that the CPU time and the memory footprint consumed by the present mcrtFOAM solver with mesh-agglomeration technique are far less than that without this technique. Convincing first implementation exercises indicate that both significant memory and CPU benefits can be expected for configurations of industrial interest These findings will contribute greatly to achieve the calculation of coupled heat transfer involving radiation within large number of mesh elements.

Using orthogonal arrays to obtain efficient and reproducible extraction conditions of geniposide and genipin in gardenia fruit with liquid chromatography-mass spectrometry determinations

The conditions to efficiently and reproducibly extract geniposide and genipin in Gardenia fruit powders were established using Taguchi experimental design approaches to improve extraction recovery. Geniposide, the major iridoid glycoside component of Gardenia fruits, which has been recognized to have choleretic effects, is transformed to Genipin in animals. In this study, the extraction conditions of geniposide and genipin such as solvent types, solvent acidities and boiling times were investigated under the guidance of experimental designs to obtain the highest content in extracts determined with liquid chromatography-mass spectrometry (LC-MS) methods. Herbal powders ground from Gardenia fruits, Gardenia jasminoides Ellis and Gardenia jasminoides Ellis var. grandiflora Nakai, were used. This paper has successfully demonstrated the use of Taguchi orthogonal arrays to obtain proper extraction conditions of geniposide and genipin in the above fruits. These design methods are capable of obtaining the optimum extraction conditions in only nine trials in which three factors, namely solvent type, boiling time and solvent acidity are investigated. The results show that solvent acidity is the influencing factor in achieving adequate contents and the other factors only have minor influences. The highest content obtained is similar to the reported data. In addition, using Taguchi orthogonal arrays within four experimental trials has identified that the extraction of ground fine powders results in more reproducible recovery than that of coarse ones.