• Journal of Electrochemical Science and Technology
• /
• v.4 no.2
• /
• pp.47-56
• /
• 2013

Inhibition performance of Lornoxicam & Tenoxicam against corrosion of carbon steel in 1M $H_2SO_4$ solutions was investigated by weight loss, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) measurements. The inhibition efficiency increased with increasing inhibitor's concentration, but decreased with increase in temperature. Potentiodynamic polarization curves showed that, the inhibitors were of mixed type. The apparent activation energy ($E^*_a$) and other thermodynamic parameters for the corrosion process have also been calculated and discussed. The inhibition of carbon steel corrosion is due to the adsorption of the inhibitor molecules on the surface, which follows Temkin adsorption isotherm. The mechanism of inhibition was discussed in the light of the chemical structure of the undertaken inhibitors.

• Corrosion Science and Technology
• /
• v.10 no.4
• /
• pp.125-130
• /
• 2011

This study was performed to improve the corrosion resistance and the stability of passive film on copper tube by potentiostatic polarization method in synthetic tap water. Formation of passive film was carried out by anodic potentiostatic polarization at various passivation potentials and passivation times in 0.1 M NaOH solution. Stability of passive film and corrosion resistance was evaluated by self-activation time, ${\tau}_0$ from passive state to active state on open-circuit state in 0.1 M NaOH solution. Addition of polyphosphate in NaOH solution prolonged the self-activation time and improved the corrosion resistance, and the addition of 5 ppm polyphosphate was most effective. It was also observed that better corrosion resistance was obtained by potentiostatic polarization at 1.0 V (vs. SCE) than at any other passivation potentials. Passivated copper tube showed perfect corrosion resistance for the immersion test in synthetic tap water showing that the anodic potentiostatic polarization treatment in 0.1 M NaOH with 5 ppm polyphosphate solution would be effective in improving the corrosion resistance and preventing the blue water problem.

• Proceedings of the Optical Society of Korea Conference
• /
• 2009.10a
• /
• pp.359-360
• /
• 2009

This paper reports experimental results on temporal characteristics of injection-locked polarization switching of a conventional type 1.55-${\mu}m$ wavelength single-mode vertical-cavity surface-emitting laser (VCSEL). The polarization of external injection beam was kept orthogonal to main mode of VCSEL. The relation for variation of intensity of two polarization modes of VCSEL with wavelength detuning for various repetition rates of injection pulse is reported.

• Corrosion Science and Technology
• /
• v.4 no.6
• /
• pp.231-235
• /
• 2005

The inhibitive effect of extracts of tamarind seeds and jackfruit seeds, curry leaves and henna leaves on corrosion of mild steel in 1M HCl solution have been studied by weight loss, potentiodynamic polarization and impedance measurements. Results obtained from the electrochemical techniques were in good agreement with weight loss results. From the weight loss data, the values of surface coverage ($\Theta$) and corrosion rate were calculated. The inhibition efficiency (IE) increased with increasing inhibitor concentration in 1M HCl solution. In all the cases the adsorption of the natural product extracts on the mild steel surface from 1M HCl follows the Langmuir adsorption isotherm relationship. Potentiodynamic polarization studies reveal the fact that all the four natural product extracts act as mixed type inhibitors. The decrease in the inhibition efficiency follows the order: Extracts of jackfruit seed>henna leaves>curry leaves>tamarind seed.

• Journal of Ginseng Research
• /
• v.42 no.1
• /
• pp.68-74
• /
• 2018

Background: Ginsenosides have been reported to have many health benefits, including anti-inflammatory effects, and the resolution of inflammation is now considered to be an active process driven by M2-type macrophages. In order to determine whether ginsenosides modulate macrophage phenotypes to reduce inflammation, 11 ginsenosides were studied with respect to macrophage polarization and the resolution of inflammation. Methods: Mouse peritoneal macrophages were polarized into M1 or M2 phenotypes. Reverse transcription-polymerase chain reaction, Western blotting, and measurement of nitric oxide (NO) and prostaglandin $E_2$ levels were performed in vitro and in a zymosan-induced peritonitis C57BL/6 mouse model. Results: Ginsenoside $Rg_3$ was identified as a proresolving ginseng compound based on the induction of M2 macrophage polarization. Ginsenoside $Rg_3$ not only induced the expression of arginase-1 (a representative M2 marker gene), but also suppressed M1 marker genes, such as inducible NO synthase, and NO levels. The proresolving activity of ginsenoside $Rg_3$ was also observed in vivo in a zymosan-induced peritonitis model. Ginsenoside $Rg_3$ accelerated the resolution process when administered at peak inflammatory response into the peritoneal cavity. Conclusion: These results suggest that ginsenoside $Rg_3$ induces the M2 polarization of macrophages and accelerates the resolution of inflammation. This finding opens a new avenue in ginseng pharmacology.

• BMB Reports
• /
• v.53 no.11
• /
• pp.600-604
• /
• 2020

Macrophages are re-educated and polarized in response to myocardial infarction (MI). The M2 anti-inflammatory phenotype is a known dominator of late stage MI. Mesenchymal stem cells (MSCs) represent a promising tool for cell therapy, particularly heart related diseases. In general, MSCs induce alteration of the macrophage subtype from M1 to M2, both in vitro and in vivo. We conjectured that hypoxic conditions can promote secretome productivity of MSCs. Hypoxia induces TGF-β1 expression, and TGF-β1 mediates M2 macrophage polarization for anti-inflammation and angiogenesis in infarcted areas. We hypothesized that macrophages undergo advanced M2 polarization after exposure to MSCs in hypoxia. Treatment of MSCs derived hypoxic conditioned medium (hypo-CM) promoted M2 phenotype and neovascularization through the TGF-β1/Smad3 pathway. In addition, hypo-CM derived from MSCs improved restoration of ischemic heart, such as attenuating cell apoptosis and fibrosis, and ameliorating microvessel density. Based on our results, we propose a new therapeutic method for effective MI treatment using regulation of macrophage polarization.

• Journal of Welding and Joining
• /
• v.19 no.1
• /
• pp.65-74
• /
• 2001

A study on the corrosion behavior in case of As-welded and PWHT temperature 55$0^{\circ}C$ of welding part of RE36 steel for marine structure was investigated with parameters such as micro-Vickers hardness, corrosion potential measurement of weld metal(WM), base metal(BM) and heat affected zone(HAZ), both Al anode generating current and Al anode weight loss quantity under sacrificial anode cathodic protection conditions. And also we carried out slow strain rate test(SSRT) in order to research both limiting cathodic polarization potential for hydrogen embrittlement and optimum cathodic protection potential as well as mechanical properties by post-weld heat treatment(PWHT) effect. Hardness of HAZ was the highest among three parts(WM, BM and HAZ) and the highest galvanic corrosion susceptibility was HAZ. And the optimum cathodic polarization potential showing the best mechanical properties by SSRT method was from -770mV to -875mV(SCE). In analysis of SEM fractography, applied cathodic potential from -770mV to -875mV(SCE) it appeared dimple pattern with ductile fracture while it showed transgranular pattern (Q. C : quasicleavage) under -900mV(SCE). However it is suggested that limiting cathodic polarization potential indicating hydrogen embrittlement was under -900mV(SCE).

• Journal of the Korean Institute of Gas
• /
• v.9 no.4 s.29
• /
• pp.30-35
• /
• 2005

In order to examine the electrochemical polarization characteristics of hydrogen embrittlement far STS444 with welding conditions, this paper carried out the accelerated hydrogen osmosis test and the electrochemical polarization test. That is, in $0.5M\; H_2SO_4+0.001M\;As_2O_3$ solution, the hydrogen embrittlement behavior of STS444 added to load of $1,400kg/cm^2$ together with hydrogen osmosis by current of $30mA/cm^2$ far 60 min. was considered. In researching the electrochemical polarization characteristics of hydrogen embrittlement for STS444 with welding conditions, the previous study clarified that tensile strength or elongation became low influenced by absorption of oil or water before welding. In this paper, we proposed the advanced mechanism of hydrogen embrittlement that integrated electrochemical corrosion with the existing mechanism of hydrogen embrirtlement.

• Membrane Journal
• /
• v.2 no.1
• /
• pp.59-66
• /
• 1992

The experimental studies were carried out on ultrafiltration of PEG #6000 and dextran 70T macromole¬cules. using an asymmetric cellulose acetate membrane in a cross flow plane type cell. Effects of pressure difference. feed concentration were studied on permeate flux and observed rejection for both the macromole¬cules. and the concentration polarization layer resistance $R_{b1}$ on permeate flux was analysed. The concentration polarization layer resistance $R_{b1}$ was correlated with the average macromolecule concen¬tration $C_{b1}$ in polarization layer. The resulting dimensionless correlation was expressed as : $\frac{R_{b1}}{{R_m}}=\alpha[\frac{\rho_{b1}}{C_{b1}}]^\beta$

• Korean Journal of Optics and Photonics
• /
• v.13 no.1
• /
• pp.32-37
• /
• 2002

Passive polarization mode splitters at λ= 1.55 ${\mu}{\textrm}{m}$ were designed and fabricated based on Ti:x-cut LiNbO$_3$ single-mode optical waveguide and two-mode interference theory. The splitting ratio with waveguide width 8 ${\mu}{\textrm}{m}$, branching angle 0.55$^{\circ}$ and interfering length 470 ${\mu}{\textrm}{m}$ showed 16.18 dB, 21.25 dB for TE and TM input polarization modes, respectively. Polarization cross-talk of -16.28 dB and -21.28 dB for TE and TM modes was achieved. Total insertion losses of 2.24 dB/cm (TE) and 2.41 dB/cm (TM) were also measured. The devices operated nearly wavelength independently over a range or 30 nm.