• BMB Reports
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• v.37 no.2
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• pp.239-245
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• 2004

We have previously demonstrated that the redox reactant pyruvate prevents apoptosis in the oxidant model of bovine pulmonary artery endothelial cells (BPAEC), and that the anti-apoptotic mechanism of pyruvate is mediated in part via the mitochondrial matrix compartment. However, cytosolic mechanisms for the cytoprotective feature of pyruvate remain to be elucidated. This study investigated the pyruvate protection against endothelial cytotoxicity when the glycolysis inhibitor 2-deoxy-D-glucose (2DG) was applied to BPAEC. Millimolar 2DG blocked the cellular glucose uptake in a concentration- and time-dependent manner with >85% inhibition at $\geq$5 mM within 24 h. The addition of 2DG evoked BPAEC cytotoxicity with a substantial increase in lipid peroxidation and a marked decrease in intracellular total glutathione. Exogenous pyruvate partially prevented the 2DG-induced cell damage with increasing viability of BPAEC by 25-30%, and the total glutathione was also modestly increased. In contrast, 10 mM L-lactate, as a cytosolic reductant, had no effect on the cytotoxicity and lipid peroxidation that are evoked by 2DG. These results suggest that 2DG toxicity may be a consequence of the diminished potential of glutathione antioxidant, which was partially restored by exogenous pyruvate but not L-lactate. Therefore, pyruvate qualifies as a cytoprotective agent for strategies that attenuate the metabolic dysfunction of the endothelium, and cellular glucose oxidation is required for the functioning of the cytosolic glutathione/NADPH redox system.

• Advances in environmental research
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• v.1 no.1
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• pp.37-55
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• 2012

Here we show that perchlorate reduction during pitting corrosion of zero-valent titanium (ZVT) is likely caused by dissolved titanium species, especially Ti(II). Several possible mechanisms were suggested based on the literature and were evaluated based on experimental observations. Direct reduction of perchlorate on the bare metal of the ZVT electrode was thermodynamically infeasible due to the high anodic potential that was applied. Other potential mechanisms were considered such as reduction by small ZVT metal particles released from the electrode and direct reduction on the oxide layer of the electrode where potential was sufficiently reduced by a high ohmic potential drop. However, these mechanisms were not supported by experimental results. The most likely mechanism for perchlorate reduction was that during pitting corrosion, in which ZVT is partially oxidized to form dissolved ions such as Ti(II), which diffuse from the electrode surface and react with perchlorate in solution. This mechanism is supported by measurements of the dissolution valence and the molar ratio of ZVT consumed to perchlorate reduced (${\Delta}Ti(0)/{\Delta}ClO_4{^-}$). The results shown in this study demonstrate that ZVT undergoing pitting corrosion has the capability to chemically reduce perchlorate by producing dissolved Ti(II) and therefore, it has the potential to be applied in treatment systems. On the other hand, the results of this research imply that the application of ZVT undergoing pitting corrosion in treatment systems may not be feasible now due to several factors, including material and electricity costs and possible chloride oxidation.

• Advances in nano research
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• v.3 no.2
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• pp.97-109
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• 2015

Citrate ion is a commonly used reductant in metal colloid synthesis, undergoes strong surface interaction with silver nanocrystallites. The slow crystal growth observed as a result of the interaction between the silver surface and the citrate ion makes this reduction process unique compared to other chemical and radiolytic synthetic methods. The antimicrobial effects of silver (Ag) ion or salts are well known, but the effects of citrate coated Ag nanoparticles (CAgNPs) are scant. Herein, we have isolated biofilm causative bacteria and fungi from drinking water PVC pipe lines. Stable CAgNPs were prepared and the formation of CAgNPs was confirmed by UV-visible spectroscopic analysis and recorded the localized surface plasmon resonance of CAgNPs at 430 nm. Fourier transform infrared spectroscopic analysis revealed C=O and O-H bending vibrations due to organic capping of silver responsible for the reduction and stabilization of the CAgNPs. X-ray diffraction micrograph indicated the face centered cubic structure of the formed CAgNPs, and morphological studies including size (average size 50 nm) were carried out using transmission electron microscopy. The hydrodynamic diameter (60.7 nm) and zeta potential (-27.6 mV) were measured using the dynamic light scattering technique. The antimicrobial activity of CAgNPs was evaluated (in vitro) against the isolated fungi, Gram-negative and Gram-positive bacteria using disc diffusion method and results revealed that CAgNPs with 170ppm concentration are having significant antimicrobial effects against an array of microbes tested.

• Journal of Environmental Health Sciences
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• v.31 no.4 s.85
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• pp.332-339
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• 2005

The environmental regulations in the world has been reinforced and many nations has devoted themselves to the development of cost-effective technology. Selective catalyst reduction(SCR) and selective non-catalyst reduction (SNCR) processes are mainly used to treat nitrogen oxidants generated from fossil-fuel combustion. One of these typical technologies for reduction of do-NOx is SNCR process has increased continuously because of the low cost for building and maintenance. Nevertheless the researches on the application to real scale plant by the reductant like Urea are rarely studied. In this paper, an experimental investigations were performed on the SNCR process in the industrial waste incineration plant. With no reducing agent, the concentration of NOx stayed in around 180 ppm $(O_2\;12\%)$ with the exhausting temperature of $950^{\circ}C$ and changed within the range of 20 ppm to remain relatively consistent. When $10\;wt\%)$ of a solution was added, the efficiency of denitrification reached above $61.4\%$ with the NSR of 2.0 and the exhausting temperature of $950^{\circ}C.$ When the concentration of the urea solution was set to $10\;wt\%$ and the sprinkling to four nozzles, the reaction temperature was reduced to about $50~100^{\circ}C$ with a mixture of $10\;wt\%\;CH_3OH\;and\;5wt\%\;Na_2CO_3$ in $40\;wt\%$ of the solution. The NOx removal efficiency increased to $78.4\%,$ achieving a broader and expansive range of reaction temperatures than the addition of an unmixed pure solution.

• Resources Recycling
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• v.14 no.1
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• pp.26-32
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• 2005

A study on the preparation of Ag fine particles was performed through a reduction reaction using ascorbic acids as a reductant, which is one of the indispensable processes for the recycling of silver-bearing wastes. Silver nitrate solution in the range of 10~120 mmole/l was used and Tamol NN8906 or PVP was also used as a dispersant in the preparation of Ag fine particles size analyze, SEM, and TEM to determine the particle size and morphology of them. As a result, the reduction reaction of silver ions with ascorbic acid reached equilibrium within 10 min. It was found that about 60% excess of ascorbic acid was required in order to reduce completely silver ions in the solution. The particle size distribution of Ag particles prepared through the reduction reaction showed typically biomodal or trimodal distribution. Especially, initial Ag concentration in the solution, the type and amount of dispersant added during the reduction reaction played an important role in determining the mean particle size of Ag particles.

• Resources Recycling
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• v.9 no.4
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• pp.37-43
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• 2000

Leaching of $LiCoO_2$ as a cathodic active materials for recovering Li and Co from spent lithium ion battery was investigated in terms of reaction variables. At the optimum condition determined in the previous work, Li and Co in a $H_2SO_4$ and $HNO_3$ solution were dissolved 70~80% and 40%, respectively. Li and Co were leached over 95% with the addition of a reductant such as $Na_2S_2O_3$ or $H_2O_2$. This behavior is probably due to the reduction of $Co^{3+}$ to $Co^{2+}$. Leaching of $LiCoCo_2$ powder obtained by calcination of an electrode materials from spent batteries was also carried out. Leaching efficiency of Li and Co were over 99% at the optimum condition with $H_2O_2$ addition of 1.7 vol.%. It seems to be due to the activation of $LiCoO_2$ by repeated charging and discharging or an imperfect crystal structure by deintercalation of Li.

• Resources Recycling
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• v.15 no.4 s.72
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• pp.19-26
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• 2006

The preparation of Ag nano-powder from aqueous silver nitrate solution, which would be available for the recycling of silver bearing wastes, was investigated by a reductive precipitation reaction using hydrazine hydrate as a reducing agent. Silver solution was prepared by dissolving silver nitrate with distilled water, and then the dispersant, Tamol NN8906 or Tween 20, was also mixed to avoid the agglomeration of particles during the reductive reaction followed by the addition of hydrazine hydrate to prepare Ag nano-particles. Ag particles obtained from the reduction reaction from silver solution were characterized using the particle size analyzer and TEM to determine the particle size distribution and morphology. It was found that about 100% excess of hydrazine hydrate was required to reduce completely silver ions in the solution. Ag powders with very narrow distribution could be obtained when Tamol NN8906 was used as the dispersant. In case of Tween 20, the particle size distribution showed typically the bimodal or multimodal distribution and the morphology of Ag particles was found to be irregular shape in both cases.

• Advances in nano research
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• v.5 no.4
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• pp.359-372
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• 2017

Metallic copper nanoparticles were synthesised by reduction of copper ions in aqueous solution, and metal-metal bonding by using the nanoparticles was studied. A colloid solution of metallic copper nanoparticles was prepared by mixing an aqueous solution of $CuCl_2$ (0.01 M) and an aqueous solution of hydrazine (reductant) (0.2-1.0 M) in the presence of 0.0005 M of citric acid and 0.005 M of n-hexadecyltrimethylammonium bromide (stabilizers) at reduction temperature of $30-80^{\circ}C$. Copper-particle size varied (in the range of ca. 80-165 nm) with varying hydrazine concentration and reduction temperature. These dependences of particle size are explained by changes in number of metallic-copper-particle nuclei (determined by reduction rate) and changes in collision frequency of particles (based on movement of particles in accordance with temperature). The main component in the nanoparticles is metallic copper, and the metallic-copper particles are polycrystalline. Metallic-copper discs were successfully bonded by annealing at $400^{\circ}C$ and pressure of 1.2 MPa for 5 min in hydrogen gas with the help of the metalli-ccopper particles. Shear strength of the bonded copper discs was then measured. Dependences of shear strength on hydrazine concentration and reduction temperature were explained in terms of progress state of reduction, amount of impurity and particle size. Highest shear strength of 40.0 MPa was recorded for a colloid solution prepared at hydrazine concentration of 0.8 M and reduction temperature of $50^{\circ}C$.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.3
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• pp.74-79
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• 2021

This study examined the mixing efficiency of exhaust gas and urea according to the mixer shape in the SCR system. For the experiment, an SCR simulation system was manufactured, and a uniformity detector was attached to the catalyst location to measure the uniformity. The experiment was conducted by setting the exhaust-gas flow rate, temperature, mixer type, and catalyst distance as variables. The experimental results confirmed the swirl angle analysis, urea number distribution, and uniformity. The swirl angle experiment of Models A and B confirmed that the swirl angle of Model A was formed approximately 7 to 8 degrees higher over the entire RPM range. When there was no mixer in the SCR system, the urea and water were concentrated to one side. Mixer Model A showed an even distribution overall, and Model B showed a slightly concentrated tendency at the beginning but then showed a stable distribution of urea. The mixing efficiency of 90%, which was the uniformity target, could be satisfied in Model A and Model B. In particular, Model A showed excellent results that satisfied 90% efficiency at 10 cm of the catalyst position.

• Resources Recycling
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• v.30 no.2
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• pp.46-52
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• 2021

Off-grade Ti generated from smelting and mechanical processing has a high oxygen content. In this work, off-grade Ti was deoxidized using Mg and a chloride mixture as the reductant and flux, respectively. The experiments were conducted in the α-Ti temperature range (1,023~1,123 K) and the effects of the reaction time, reaction temperature, quantitiy of Mg and chloride ratio on deoxidation were investigated. Notably, when YCl3 is used as the flux to react with MgO, it is possible to reduce the activity of MgO. Therefore Ti can be deoxidized using Mg. In this study, the O content was decreased from 0.5 wt% to 0.1004 wt% at 1073 K, for 6 hours, with Mg=3.6 g and $X_{YCl_3}=0.22$.