• Journal of the Korean institute of surface engineering
• /
• v.51 no.5
• /
• pp.325-331
• /
• 2018

Calcium carbonate($CaCO_3$) films were formed by an eco-friendly electro-chemical technique on steel substrates in synthesized distilled water solutions containing $NaHCO_3$, $CaCl_2$ and $MgCl_2$ with different ratio respectively. It was investigated to confirm the effect of $Mg^{2+}$ concentration by Scanning Electron Microscopy(SEM), Energy Dispersive x-ray Spectroscopy(EDS) and X-Ray Diffraction(XRD) respectively. From an experimental result, only calcite crystals were found in solution containing no $Mg^{2+}$. By increasing concentration of $Mg^{2+}$, deposition rate decreased and crystal structure was transformed form calcite to aragonite. In case of including $MgCl_2$ 300mM in synthesized solutions containing $NaHCO_3$, $CaCl_2$ 60mM, it was showed over the 90% of aragonite contents which have quite high deposition rate of aragonite. Also, it was confirmed that $Mg^{2+}$ acted as inhibitor on the films which made transforming from calcite to aragonite.

• Analytical Science and Technology
• /
• v.20 no.6
• /
• pp.483-487
• /
• 2007

Electrochemistry of 1.0 mM bis(1,10-phenanthroline)copper(II) $(Cu(ph){_2}^{2+})$ in 100 mM NaCl solution including 27 mM $MgCl_2$ with and without sodium dodecyl sulfate (SDS) is studied. In the presence of SDS, $E_{pa}$ and $E_{1/2}$ of $Cu(ph){_2}^{2+}$ by adding $Mg^{2+}$ shifts to a positive direction compared to the SDS free. The intersection of two lines on ${\Delta}E_p$ vs -log[SDS] plot is determined as a critical micelle concentration (CMC). When $Mg^{2+}$ is added, it seems that the double layer became more compact. And the formation of micelles is retarded.

• Korean Journal of Animal Reproduction
• /
• v.26 no.1
• /
• pp.73-78
• /
• 2002

This study was conducted to investigate total protein, DNA, and RNA content in corpus luteum(CL) without and with central cavity in dairy cow. Stage of the estrous cycle of corpus luteum from slaughterhouse(CL3, days 11 to 17) was classified by method of Ireland et. al.(1980). Corpus luteum was classified into corpus luteum without(less than 2mm in diameter) and with central cavity(more than 2mm in diameter) by method of Kastelic et. al.(1990). 1 In total protein content, CL with central cavity did not differ from CL without central cavity. 2. In DNA content, CL with central cavity was significantly lower than CL without central cavity(p＜0.05). 3. In protein: DNA ratios, CL with central cavity was significantly lower than CL without central cavity(p＜0.05). 4. But in RNA content, protein:RNA and RNA:DNA ratios, CL with central cavity did not differ from CL without central cavity.

• Applied Microscopy
• /
• v.30 no.4
• /
• pp.389-401
• /
• 2000

The mouse for identifying the histological changes of kidney were also divided into the two groups; treated with only $HgCl_2$ (4 mg/kg), the group treated with $HgCl_2$ and squalene (200 mg/kg). The $HgCl_2$ treated only one time at first day. The squalene treated two times a day (12 hours interval) for every day. Each groups were divided into the five groups; 6, 12, 24, 48 and 72 hours after treated $HgCl_2$ and squalene. Historical changes of the kidneys were investigated by electron microscope. The group with only $HgCl_2$ showed that the nuclear membrane was shrinked, the inner membrane (cristae) of the mitochondria were destructed, and ribosomes on the rough endoplasmic reticulum were lost. The group treated with $HgCl_2$ and Squalene showed that the nuclear membrane was more rounded, the cristae of the mitochondria were almost normal shape, and more ribosomes on the rough endoplasmic reticulum were attached. Therefore , we concluded that squalene has significantly protective effects in kidney to harmful $HgCl_2$.

• Journal of Korean Society of Environmental Engineers
• /
• v.22 no.4
• /
• pp.599-607
• /
• 2000

In this research, ${NH_4}^+-N$ and ${PO_4}^{3-}-P$ in wastewater were removed by crystallization. Nitrogen and phosphate have been regarded as key nutrients in the eutrophication of rivers and lakes. Struvite, $MgNH_4PO_4{\cdot}6H_2O$, is insoluble in alkaline solutions. Fertilizer industry wastewater contains organic and nitrogen concentration of 330 mg/L and 550 mg/L, respectively. Nitrogen in this wastewater cannot be treated by conventional biological treatment without physicochemical pretreatment, because nitrogen concentration is relatively high compared to organic concentration. Magnesium ions used in this study were from bittern and commercial magnesium salts of $MgCl_2$ and $Mg(OH)_2$. Bittern obtained as a by-product of seasalt manufacture contains $8,000mg\;Ca^{2+}/L$ and $32,000mg\;Mg^{2+}/L$. Optimum initial pH was 10.5~11.0 and the reaction was complete or done in 2 min. Nitrogen removal efficiency using bittern, $MgCl_2 $ and $Mg(OH)_2$ (as source of $Mg^{2+}$) was 71 %, 81% and 83%. respectively. Phosphate removal efficiency was 99%, 98% and 93%, respectively. Therefore, bittern, $MgCl_2$ and $Mg(OH)_2$ can be efficiently used as $Mg^{2+}$ source for crystallization of nitrogen and phosphate. However, bittern is economically favorable $Mg^{2+}$ source for removing nitrogen and phosphate in wastewater.

• Journal of Korean Association for Spatial Structures
• /
• v.6 no.4 s.22
• /
• pp.73-80
• /
• 2006

It is an object of the present paper to investigate a electrochemical properties of Mg-based sacrificial anodes and the effect of calcium added from calcium chloride into magnesium on the melt protection during the melting. Electrochemical data will be correlated with processing control variables, and the microstructural change by the addition of CaCl2. Small addition of calcium into magnesium from CaCl2 imparts beneficial effect in electrochemical properties of Mg alloys, primarily, through microstructural modifications. In addition, the protection effect of the melts surface of Ca with low melting point modification is obtained by adding Ca not more than 0.6%.

• Journal of Korean Society of Environmental Engineers
• /
• v.35 no.10
• /
• pp.730-736
• /
• 2013

This study was conducted to examine the effects of the salt concentration in seafood wastewater on the high-rate anaerobic digestion process. In the general high-rate anaerobic process test, the TCODcr removal efficiency at 6 hr or more HRT was 81.1~0.7%, and the optimal HRT for seafood wastewater process was found to be 6 hr or more. The methane content in the biogas was 70.1~76.8% during the operation, and was hardly affected by the change in the influent load. The results of the anaerobic digestion efficiency according to the salt concentration showed that the removal efficiency of TCODcr was 83.4~89.2% below a $4,000mgCl^-/L$ salt concentration, and mid-70% at a $5,000mgCl^-/L$ salt concentration. Therefore, the salt concentration had to be kept below $4,000mgCl^-/L$ to ensure stable treatment efficiency. Below a $3,000mgCl^-/L$ salt concentration, the methane generation was 0.2999~0.346$m^3CH_4/kgCODrem.$, which was similar to the theoretical methane gas generation in STP condition ($0.35m^3CH_4/gTCODrem.$). The methane content in the biogas was 64.7~73.3% below a $3,000mgCl^-/L$ salt concentration, but decreased with an increase in the salt concentration, to 50.1~56.9% at a $4,000mgCl^-/L$ concentration.

• Elastomers and Composites
• /
• v.53 no.3
• /
• pp.158-167
• /
• 2018

In this study, in-situ trans-selective polymerization of isoprene was carried out using titanium-based Ziegler-Natta catalysts. The catalysts were prepared by high-energy ball milling. Individually Large-inner-diameter carbon nanotubes (CNTL), and hydroxylated carbon nanotubes (CNTOH), along with magnesium chloride ($MgCl_2$) were used as the carriers for the catalysts. The optimum ball-milling time for preparing the $CNT/MgCl_2/TiCl_4$ Ziegler-Natta catalysts was 4 h. The $CNTOH/MgCl_2/TiCl_4$ catalyst showed a higher efficiency than that of the $CNTL/MgCl_2/TiCl_4$ catalyst, based on the rate of polymerization. The effects of the CNT-filler type on the isoprene polymerization behaviors and polymer properties were investigated. The morphologies of the trans-1,4-polyisoprene (TPI)/CNT and TPI/CNTOH nanocomposites exhibited a tube-like shape, and the CNTL and CNTOH fillers were well dispersed in the TPI matrix. In addition, the thermal stability of TPI significantly increased upon the introduction of a small amount of both CNTL/CNTOH fillers (0.15 wt%), owing to the satisfactory dispersion of the CNTL/CNTOH in the TPI matrix.

• Membrane Journal
• /
• v.27 no.3
• /
• pp.240-247
• /
• 2017

In this study, the heterogeneous ion exchange membranes prepared by the combination of the carbon electrode and mixed the cation and anion exchange polymers and polyvinylidene fluoride as the basic polymer together were made to recognize the efficiency of the salt removal for the application of the membrane capacitive deionization process. The mixing weight ratio of the solvent, basic polymer and ion exchange resin was 7 : 2 : 1 and this mixed solution was directly cast on the electrode. As for the operating conditions of the adsorption voltage and time, feed flow rate, desorption voltage and time of the feed solution NaCl 100 mg/L, the salt removal efficiencies (SRE) were measured. Apart from this NaCl, the $CaCl_2$ and $MgSO_4$ solutions were investigated in terms of SRE as well. Typically, SRE for NaCl 100 mg/L solution under the conditions of adsorption voltage/time, 1.5 V/3 min, desorption voltage/time -0.1 V/3 min, was shown 98%. And for the $CaCl_2$ and $MgSO_4$ solutions, the SREs of 70 and 59% were measured under the conditions of adsorption voltage/time, 1.2 V/3 min, desorption voltage/time -0.5 V/5 min, respectively.

• Journal of Powder Materials
• /
• v.16 no.1
• /
• pp.43-49
• /
• 2009

Titanium carbides are widely used for cutting tools and grinding wheels, because of their superior physical properties such as high melting temperature, high hardness, high wear resistance, good thermal conductivity and excellent thermal shock resistance. The common synthesizing method for the titanium carbide powders is carbo-thermal reduction from the mixtures of titanium oxide($TiO_2$) and carbon black. The purpose of the present research is to fabricate nano TiC powders using titanium salt and titanium hydride by the mechanochemical process(MCP). The initial elements used in this experiment are liquid $TiCl_4$(99.9%), $TiH_2$(99.9%) and active carbon(<$32{\mu}m$, 99.9%). Mg powders were added to the $TiCl_4$ solution in order to induce the reaction with Cl-. The weight ratios of the carbon and Mg powders were theoretically calculated. The TiC and $MgCl_2$ powders were milled in the planetary milling jar for 10 hours. The 40 nm TiC powders were fabricated by wet milling for 4 hours from the $TiCl_4$+C+Mg solution, and 300 nm TiC particles were obtained by using titanium hydride.