• Analytical Science and Technology
• /
• v.37 no.1
• /
• pp.47-62
• /
• 2024

Abu Gurdi area is located in the South-eastern Desert of Egypt which considered as volcanic massive sulfide deposits (VMS). The present work aims at investigating the ore mineralogy of Abu Gurdi region in addition to the effectiveness of the hydrometallurgical route for processing these ores using alkaline leaching for the extraction of Zn, Cu, and Pb in the presence of hydrogen peroxide, has been investigated. The factors affecting the efficiency of the alkaline leaching of the used ore including the reagent composition, reagent concentration, leaching temperature, leaching time, and Solid /Liquid ratio, have been investigated. It was noted that the sulfide mineralization consists mainly of chalcopyrite, sphalerite, pyrite, galena and bornite. Gold is detected as rare, disseminated crystals within the gangue minerals. Under supergene conditions, secondary copper minerals (covellite, malachite, chrysocolla and atacamite) were formed. The maximum dissolution efficiencies of Cu, Zn, and Pb at the optimum leaching conditions i.e., 250 g/L NaCO₃ - NaHCO₃ alkali concentration, for 3 hr., at 250 ℃, and 1/5 Solid/liquid (S/L) ratio, were 99.48 %, 96.70 % and 99.11 %, respectively. An apparent activation energy for Zn, Cu and Pb dissolution were 21.599, 21.779 and 23.761 kJ.mol^-1, respectively, which were between those of a typical diffusion-controlled process and a chemical reaction-controlled process. Hence, the diffusion of the solid product layer contributed more than the chemical reaction to control the rate of the leaching process. High pure Cu(OH)₂, Pb(OH)₂, and ZnCl₂ were obtained from the finally obtained leach liquor at the optimum leaching conditions by precipitation at different pH. Finally, highly pure Au metal was separated from the mineralized massive sulfide via using adsorption method.

• Membrane and Water Treatment
• /
• v.15 no.3
• /
• pp.107-115
• /
• 2024

This study proposes the recycling of MVS as a value-added product for the removal of phosphate from aqueous solutions. By comparing the phosphate adsorption capacity of each calcined adsorbent at each temperature of MVS, it was determined that the optimal heat treatment temperature of MVS to improve the phosphate adsorption capacity was 800 ℃. MVS-800 suggests an adsorption mechanism through calcium phosphate precipitation. Subsequent kinetic studies with MVS-800 showed that the PFO model was more appropriate than the PSO model. In the equilibrium adsorption experiment, through the analysis of Langmuir and Freundlich models, Langmuir can provide a more appropriate explanation for the phosphate adsorption of MVS-800. This means that the adsorption of phosphate by MVS-800 is uniform over all surfaces and the adsorption consists of a single layer. Thermodynamic analysis of thermally activated MVS-800 shows that phosphate adsorption is an endothermic and involuntary reaction. MVS-800 has the highest phosphate adsorption capacity under low pH conditions. The presence of anions in phosphate adsorption reduces the phosphate adsorption capacity of MVS-800 in the order of CO 3 2-, SO 4 2-, NO 3- and Cl-. Based on experimental data to date, MVS-800 is an environmentally friendly adsorbent for recycling waste resources and is considered to be an adsorbent with high adsorption capacity for removing phosphates from aqueous solutions. This paper combines the advantages of gray predictor and AI fuzzy. The gray predictor can be used to predict whether the bear point exceeds the allowable deviation range, and then perform appropriate control corrections to accelerate the bear point to return to the boundary layer and achieve.

• Journal of Trauma and Injury
• /
• v.37 no.3
• /
• pp.233-237
• /
• 2024

Bullet embolism is a potential complication of a gunshot wound, especially with a low-velocity missile. This is because the trajectory of the low-velocity bullet can be significantly slowed as it passes through tissue. An unusual form of travel can occur in which the bullet enters the vasculature but does not have enough kinetic energy to create a through-and-through wound, leading it to remain inside the vasculature. Once inside the vasculature, the bullet could migrate to different parts of the body, potentially causing complications such as ischemia, becoming a source of thromboembolism, or functioning as a nidus for infection. The management of a bullet embolism varies from case to case, as each patient with this issue has a unique body habitus that can result in infinite possibilities of the trajectory and destination of the bullet embolus. Additional damage to surrounding vasculature or tissue can occur, as well as embolization of the bullet to critical areas of the body. Here we present the case of a 72-year-old man who had a self-inflicted gunshot wound to the chest with a low-velocity bullet, which penetrated the right atrium of the heart. It traveled into the venous vasculature through the right atrium, into the inferior vena cava, and eventually settled in the right internal iliac vein. He refused further intervention and management after initial workup and resuscitation.

• Parasites, Hosts and Diseases
• /
• v.62 no.2
• /
• pp.205-216
• /
• 2024

Sigma-class glutathione transferase (GST) proteins with dual GST and prostaglandin synthase (PGS) activities play a crucial role in the establishment of Clonorchis sinensis infection. Herein, we analyzed the structural and enzymatic properties of sigma-class GST (CsGST-σ) proteins to obtain insight into their antioxidant and immunomodulatory functions in comparison with mu-class GST (CsGST-µ) proteins. CsGST-σ proteins conserved characteristic structures, which had been described in mammalian hematopoietic prostaglandin D₂ synthases. Recombinant forms of these CsGST-σ and CsGST-µ proteins expressed in Escherichia coli exhibited considerable degrees of GST and PGS activities with substantially different specific activities. All recombinant proteins displayed higher affinities toward prostaglandin H₂ (PGS substrate; average K_m of 30.7 and 3.0 ㎛ for prostaglandin D₂ [PGDS] and E₂ synthase [PGES], respectively) than those toward CDNB (GST substrate; average K_m of 1,205.1 ㎛). Furthermore, the catalytic efficiency (K_cat/K_m) of the PGDS/PGES activity was higher than that of GST activity (average K_cat/K_m of 3.1, 0.7, and 7.0×10^-3 s^-1㎛^-1 for PGDS, PGES, and GST, respectively). Our data strongly suggest that the C. sinensis sigma- and mu-class GST proteins are deeply involved in regulating host immune responses by generating PGD₂ and PGE₂ in addition to their roles in general detoxification.

• Journal of Climate Change Research
• /
• v.34 no.22
• /
• pp.9093-9113
• /
• 2021

This study examines the role of the relative wind (RW) effect (wind relative to ocean current) in the regional ocean circulation and extratropical storm track in the south Indian Ocean. Comparison of two high-resolution regional coupled model simulations with and without the RW effect reveals that the most conspicuous ocean circulation response is the significant weakening of the overly energetic anticyclonic standing eddy off Port Elizabeth, South Africa, a biased feature ascribed to upstream retroflection of the Agulhas Current (AC). This opens a pathway through which the AC transports the warm and salty water mass from the subtropics, yielding marked increases in sea surface temperature (SST), upward turbulent heat flux (THF), and meridional SST gradient in the Agulhas retroflection region. These thermodynamic and dynamic changes are accompanied by the robust strengthening of the local low-tropospheric baroclinicity and the baroclinic wave activity in the atmosphere. Examination of the composite life cycle of synoptic-scale storms subjected to the high-THF events indicates a robust strengthening of the extratropical storms far downstream. Energetics calculations for the atmosphere suggest that the baroclinic energy conversion from the basic flow is the chief source of increased eddy available potential energy, which is subsequently converted to eddy kinetic energy, providing for the growth of transient baroclinic waves. Overall, the results suggest that the mechanical and thermal air-sea interactions are inherently and inextricably linked together to substantially influence the extratropical storm tracks in the south Indian Ocean.

• Korean Journal of Veterinary Service
• /
• v.47 no.3
• /
• pp.185-191
• /
• 2024

This case report examines the efficacy of carprofen and rehabilitation therapy in a 7-year-old, 4.5 kg, spayed Poodle with unilateral forelimb lameness. Gait analysis assessed kinetic parameters such as peak vertical force (PVF), vertical impulse (VI), symmetry index (SI), and body load distribution (BLD) before and after treatment. The differences between the left and right forelimbs were recorded. Before intervention, the PVF differences between the forelimbs were -4.00% during walking and 40.00% during trotting. Two weeks post-intervention, these improved to 8.33% and 27.67%, further reducing to 6.33% and 18.00% after four weeks. VI differences also improved, with initial values of -0.67 N∙s during walking and -1.3 N∙s during trotting decreasing to -0.03 N∙s and -0.87 N∙s, respectively. SI increased from 6.23% to 11.87% during walking, while it decreased from 33.63% to 14.73% during trotting. BLD differences reduced from -1.17 cm² and -7.13 cm² to 0.23 cm² and -2.17 cm², respectively, after four weeks. These results suggest that a combination of carprofen administration and rehabilitative intervention can effectively reduce lameness and improve symmetry in dogs with unilateral forelimb lameness, as evidenced by improvements in key gait parameters over the treatment period.

• Korean Journal of Applied Biomechanics
• /
• v.34 no.3
• /
• pp.133-144
• /
• 2024

Objective: Neuromuscular training may often result in an incomplete improvement of biomechanical risk factors associated with non-contact ACL injury. This study aimed to investigate the effects of reactive neuromuscular training (RNT) on dynamic postural control of the lower extremity during single-leg drop landing (SLDL) in comparison with conventional neuromuscular training (CNT). Method: Twenty-eight recreational female athletes were randomized to a CNT group (n=15) or a RNT group (n=13). All participants performed SLDL for three-dimensional motion analysis before and after CNT and RNT. The kinematic variable was calculated from before 50 milliseconds (ms) to after 100 ms initial contact: joint angle (degree). The kinetic variable was calculated from initial contact to after 100 ms: internal net joint moment (Nm/kg). Time series curve for normalized data was represented for group means and associated 95% confidence intervals. Effect sizes using Cohen's d was also calculated. Results: In within-group differences, the CNT group showed decreased knee flexion angle (0~100% of the task) and decreased knee valgus angle (0~50% of the task) after the intervention, whereas the RNT group showed increased hip flexion angle (0~14% of the task), decreased hip adduction angle (0~100% of the task), and decreased knee valgus angle (0~100% of the task) after the intervention. In between-group differences, the RNT group exhibited more hip flexion angle (0~49, 61~91% of the task), more knee flexion angle (0~100% of the task), and less knee valgus angle (0~55% of the task) than the CNT group. Conclusion: These findings suggest that both training intervention programs modified dynamic posture of the hip and knee during SLDL. Therefore, combining a neuromuscular training program with RNT technique would be more efficient for future injury prevention efforts.

• Journal of Korean Society of Environmental Engineers
• /
• v.33 no.6
• /
• pp.396-404
• /
• 2011

An investigation on the removals of PAH-quinone compounds, which are commonly produced from the biological and/or chemical treatments of PAH-contaminated soils, from the aqueous phase via birnessite (${\delta}-MnO_2$)-mediated oxidative transformation is described. It was demonstrated that acenaphthenequinone (APQ), p-PAH quinone can be removed via birnessite-mediated oxidative-coupling reactions, and anthraquinone (AQ) and 1,4-naphthoquinone (1,4-NPQ), o-PAH quinones were efficiently removed by birnessite-mediated cross-coupling reactions in the presence of catechol (CAT) as a reactive mediator. The removals of PAH-quinone compounds followed pseudo-first-order reactions, and the rate constant (k, $hr^{-1}$) for the removals of 1,4-NPQ under the experiment conditions (1,4-NPQ = 10 mg/L, CAT = 50 mg/L, ${\delta}-MnO_2$ = 1.0 g/L, pH 5, Reaction time = 6~96 hr) was 0.0426, which was about 4 times lower than that of APQ (0.173). With the observed pseudo-first order rate constants with respect to birnessite loadings under the same experimental conditions, the surface-normalized specific rate constant, $K_{surf}$, for 1,4-NPQ was determined to be $8.5{\times}10^{-4}L/m^2{\cdot}hr$. The analysis of the kinetic data with respect to birnessite loading indicated that the cross-coupling reactions of 1,4-NPQ consist of two different reaction steps over time and the results have also been discussed in terms of the reaction mechanisms.

• Journal of Wetlands Research
• /
• v.17 no.3
• /
• pp.228-236
• /
• 2015

Urbanization causes many environmental, hydrological and ecological problems such as distortion of the natural water circulation system, increase in nonpoint source pollutants in stormwater runoff, degradation of surface water quality, and damage to the ecosystem. Due to the increase in impervious surface by urbanization, developed countries apply low impact development (LID) techniques as important alternatives to reduce the impacts of urbanization. In Korea, LID techniques were employed since 2012 in order to manage nonpoint source pollutants. LID technology is a technique for removing pollutants using a variety of physical, chemical and biological mechanisms in plants, microorganisms and filter media with the reduced effluence of stormwater runoff by mimicking natural water circulation system. These LID facilities are used in a variety of filter media, but an assessment has not been carried out for the comprehensive comparison evaluation of adsorption and desorption characteristics for the pollutant removal capacity. Therefore, this study was conducted to analyze the adsorption and desorption characteristics of various filter media used in the LID facilities such as sand, gravel, bioceramic, wood chips and bottom ash etc. in reducing heavy metals(Pb, Cu). In this study, the adsorption affinity for Pb in all filter media was higher than Cu. Pseudo second order equation and Langmuir-3 isotherm are more applicable in the adsorption kinetic model and adsorption isotherm model, respectively. As a result of the desorption experiment, the filter media does not exceed KSLT which is the hazardous substance leaching limit, showing the capability of the filter media in LID. The bioceramic and woodchip as filter medias were evaluated and exhibited excellent adsorption capacity for Pb.

• Korean Chemical Engineering Research
• /
• v.52 no.6
• /
• pp.814-820
• /
• 2014

In this work, hydrate inhibition performance of water-soluble polymers including pyrrolidone, caprolactam, acrylamide types were evaluated using torque measurement and high pressure differential scanning calorimeter (HP ${\mu}$-DSC). The obtained experimental results suggest that the studied polymers represent the kinetic hydrate inhibition (KHI) performance. 0.5 wt% polyvinylcaprolactam (PVCap) solution shows the hydrate onset time of 34.4 min and subcooling temperature of 15.9 K, which is better KHI performance than that of pure water - hydrate onset time of 12.3 min and subcooling temperature of 6.0 K. 0.5 wt% polyvinylpyrrolidone (PVP) solution shows the hydrate onset time of 27.6 min and the subcooling temperature of 13.2 K while polyacrylamide-co-acrylic acid partial sodium salt (PAM-co-AA) solution shows less KHI performance than PVP solution at both 0.5 and 5.0 wt%. However, PAM-co-AA solution shows slow growth rate and low hydrate amount than PVCap. In addition to hydrate onset and growth condition, torque change with time was investigated as one of KHI evaluation methods. 0.5 wt% PVCap solution shows the lowest average torque of 6.4 N cm and 0.5 wt% PAM-co-AA solution shows the average torque of 7.2 N cm. For 0.5 wt% PVP solution, it increases 11.5 N cm and 5.0 wt% PAM-co-AA solution shows the maximum average torque of 13.4 N cm, which is similar to the average torque of pure water, 15.2 N cm. Judging from the experimental results obtained by both an autoclave and a HP ${\mu}$-DSC, the PVCap solution shows the best performance among the KHIs in terms of delaying hydrate nucleation. From these results, it can be concluded that the torque change with time is useful to identify the flow ability of tested solution, and the further research on the inhibition of hydrate formation can be approached in various aspects using a HP ${\mu}$-DSC.