• Asian Pacific Journal of Cancer Prevention
• /
• 제15권8호
• /
• pp.3451-3455
• /
• 2014

Background: The serum carcinoembryonic antigen (CEA) level can reflect tumor growth, recurrence and metastasis. It has been reported that epidermal growth factor receptor (EGFR) mutations in exons 19 and 21may have an important relationship with tumor cell sensitivity to EGFR-TKI therapy. In this study, we investigated the clinical value of EGFR mutations and serum CEA in patients with non-small cell lung cancer (NSCLC). Materials and Methods: The presence of mutations in EGFR exons 19 and 21 in the tissue samples of 315 patients with NSCLC was detected with real-time fluorescent PCR technology, while the serum CEA level in cases who had not yet undergone surgery, radiotherapy, chemotherapy and targeted therapy were assessed by electrochemical luminescence. Results: The mutation rates in EGFR exons 19 and 21 were 23.2% and 14.9%, respectively, with the two combined in 3.81%. Measured prior to the start of surgery, radiotherapy, chemotherapy and targeted treatment, serum CEA levels were abnormally high in 54.3% of the patients. In those with a serum CEA level <5 ng/mL, the EGFR mutation rate was 18.8%, while with 5~19 ng/mL and ${\geq}20ng/mL$, the rates were 36.4% and 62.5%. In addition, in the cohort of patients with the CEA level being 20~49 ng/mL, the EGFR mutation rate was 85.7%, while in those with the CEA level ${\geq}50ng/mL$, the EGFR mutation rate was only 20.0%, approximately the same as in cases with the CEA level<5 ng/mL. Conclusions: There is a positive correlation between serum CEA expression level and EGFR mutation status in NSCLC patients, namely the EGFR mutation-positive rate increases as the serum CEA expression level rises within a certain range (${\geq}20ng/mL$, especially 20~49 ng/mL). If patient samples are not suitable for EGFR mutation testing, or cannot be obtained at all, testing serum CEA levels might be a simple and easy screening method. Hence, for the NSCLC patients with high serum CEA level (${\geq}20ng/mL$, especially 20~49 ng/mL), it is worthy of attempting EGFR-TKI treatment, which may achieve better clinical efficacy and quality of life.

• Journal of Advanced Marine Engineering and Technology
• /
• 제41권3호
• /
• pp.230-237
• /
• 2017

본 연구에서는 해상풍력 타워 지지구조물용 강재인 S355ML 강에 대하여 전기화학적 기법으로 전기방식 설계에 필요한 최적 방식전위를 규명하고자 하였다. 동전위분극 실험 결과, 양극분극 곡선 상에서는 부동태 구간은 존재하지 않으며, 음극분극 곡선 상에는 용존산소환원반응에 의한 농도분극 구간과 수소가스 발생에 의한 활성화분극 구간이 관찰되었다. 음극방식 시 방식전위에 해당하는 농도분극 구간은 약 - 0.72 V ~ - 1.0 V의 전위 구간인 것으로 확인되었다. 다양한 전위에서 정전위 실험을 실시한 결과 전류밀도 변화는 시간에 따라 안정화되는 경향을 나타냈다. 1200초 동안 정전위 실험 후 주사전자현미경과 3D 분석 현미경을 이용한 시험편 표면 분석 결과, 양극분극 전위에 해당하는 0 V ~ - 0.50 V의 전위구간에서는 양극용해반응에 의한 부식손상이 관찰되었다. 이에 반해 음극분극 전위 영역에서는 대체적으로 손상이 없는 양호한 표면을 유지하였으며 석회질 피막 형성을 확인할 수 있었다. 연구결과, 농도분극 영역에 해당하는 - 0.8 V ~ - 1.0 V의 전위영역이 S355ML 강의 외부전원법에 의한 음극방식 적용 시 최적 방식 전위 구간으로 사료된다.

• 한국표면공학회지
• /
• 제51권2호
• /
• pp.95-103
• /
• 2018

Recently, many types of constructional steels have been often exposed to under severe corrosive environments due to acid rain with increasing environmental contamination. In order to inhibit their corrosion in severe corrosive environments, a painting method has been widely applied to numerous constructional steels of land as well as marine. Therefore, development of paint having a good quality of corrosion resistance is considered to be very important. In this study, four types of anti-corrosive paints (AP: Phenol epoxy, AC: Ceramic epoxy, AT: Coal tar epoxy, AH: High solid epoxy) were coated to the specimens, and then, were immerged in various salt solutions (0.1, 0.3, 3, 6, 9 and 15% NaCl solutions) for 11 days. And, the corrosion resistance of these samples by effect of osmotic pressure with salt concentration was investigated with electrochemical methods such as measurement of corrosion potential, impedance and corrosion current density. The corrosion current densities of all samples (AC, AT and AH) submerged in 3% NaCl solution exhibited the smallest values compared to other salt solutions. However, in the case of lower values of salt solutions than 3% NaCl solution, the corrosion current density increased again because it makes easier for water, dissolved oxygen and chloride ion etc. to invade toward inner side of coating film due to increasing of the osmotic pressure than 3% NaCl solution, but in the case of higher values of salt solutions than 3% NaCl solution, the coating film is easily deteriorated due to high concentration of chloride ion rather than the osmotic pressure, which resulted in increasing the corrosion current density. In particular, the AC sample indicated the best corrosion resistance in 6% NaCl solution compared to other samples. Consequently, it is considered that the corrosion mechanism of the coated steel plate is completely different from bare steel plate, and the corrosion resistance of coating film by osmotic pressure and chloride ion depend on various types of epoxy of paint in NaCl solution.

• 보존과학회지
• /
• 제30권1호
• /
• pp.95-101
• /
• 2014

은제품은 대기의 아황산가스나 황화수소 등과 반응하여 검게 변색된다. 검은 변색은 표면에 황화은이 형성되는 것으로 보존처리시 제거하는 것이 일반적이다. 황화은을 제거하는 방법은 화학적, 전기화학적, 미세마모법 등을 사용하지만 모두 은의 손실을 초래한다. 따라서 본 연구는 표면 오염물만을 선택적으로 제거할 수 있는 레이저클리닝을 은시편에 실험하여 안전하고 효율적인 레이저 조건을 알아보고자 하였다. 먼저 부식되지 않은 순수한 은에 레이저를 조사하여 안전한 레이저에너지밀도 범위를 확인하였다. 실험 결과 은은 1064nm $4.00J/cm^2$ 이하, 532nm $2.39J/cm^2$ 이하 레이저에너지밀도 범위에서 안전하였다. 인공적으로 부식시킨 은판의 부식층(황화은)은 레이저조건 1064nm $2.39J/cm^2$로 약 5~10회, 532nm $1.19J/cm^2$로 5~10회 조사하였을 때 제거되었다. AES를 이용하여 레이저 펄스당 제거되는 부식층 두께를 확인한 결과 약 13 ~ 25nm이다. 은 시편의 레이저클리닝 조건을 은제품에 적용한 결과 표면의 검은 부식층이 제거되었으며 은 광택도 유지되었다. 이를 통해 은제품의 레이저클리닝 적용 가능성을 확인하였다.

• 대한화학회지
• /
• 제45권5호
• /
• pp.442-447
• /
• 2001

Octamethylenethiafulvalene(OMTTF)와 $HAuCl_4{\cdot}3H_2O$를 THF 용액 내에서 직접 반응시켜 $(OMTTF)AuCl_4$를 합성하였다. $(OMTTF)_2PtCl_4,\; (OMTTF)_2\;IrCl6{\cdot}2H_2O,\; (OMTTF)OsCl5{\cdot}THF$ 등은 각각 $H_2PtCl_6{\cdot}xH_2O,\;H_2IrCl_6{\cdot}xH_2O$ 및 $H_2OsCl_6$를 사용하여 유사한 방법으로 합성하였다. 합성된 화합물들은 자기적(EPR, 자화율 측정), 분광학적(IR, UV-Vis), 전기화학적(CV) 특성과 전기전도도를 측정하였다. 상온에서의 분말 전기전도도는 모두 ~$10^{-7}\; S{\cdot}cm^{-1}$ 이하의 낮은 전기전도도를 나타내었다. 합성 과정에서 OMTTF로부터 Au, Pt, Ir, Os 금속 화합물로 전하 이동이 이루어져 OMTTF는 완전히 이온화된 $OMTTF^+$ 양이온 라디칼로 존재하였다. $OMTTF^+$ 양이온 라디칼의 안정성은 산화·환원 전위 값에서 확인하였다. 자화율 결과로부터 $(OMTTF)_2IrCl_6{\cdot}2H_2O$ 및 $(OMTTF)OsCl5{\cdot}THF$에서는 $OMTTF^+$ 이온에 존재하는 홀전자와 중심 금속(Ir 및 Os)에 편재화된 홀전자들 사이에는 강한 반강자성 상호작용이 존재함을 알 수 있었다.

• Journal of Preventive Medicine and Public Health
• /
• 제35권3호
• /
• pp.229-235
• /
• 2002

Objectives : To evaluate the effects on the formation of benzidine-hemoglobin, and benzidine metabolite-hemoglobin adducts, caused by pretreatment with the known xenobiotic metabolism effectors, ethanol and phenobarbital, in rats administered Direct Black 38 dye. Methods : The experimental rats were divided into three groups: a control group, an ethanol group and a phenobarbital group. Rats were pretreated with ethanol (1g/kg) or phenobarbital (80mg/kg) 24 hours prior to the oral administration of Direct Black 38 (0.5mmol/kg), with the control group being administered the same amount of distilled water. Blood samples were obtained from the vena cava of 5 rats from each group prior to, and at 30 min, 3h, 5h, 9h, 12h, 24h, 48h, 72h, 96h, and 144h following the oral administration of Direct Black 38. Directly after sampling the blood was separated into hemoglobin and plasma, with the adducts being converted into aromatic amines by basic hydrolysis. Hydrolyzed benzidiene, monoacetylbenzidine and 4-aminobiphenyl were analyzed by reverse-phase liquid chromatography with an electrochemical detector, The quantitative amount of the metabolites was expressed by the hemoglobin binding index (HBI). Results : In the ethanol group, benzidine-, monoacetylbenzidine-, and 4-aminobiphenyl-HBI were increased to a greater extent than those in the control group. These results were attributed to the ethanol inducing N-hydrgxylation, which is related to the formation of the hemoglobin adduct, In the phenobarbital group, all the HBIs, with the exception of the benzidine-HBI, were increased to a greater extent than those of the control group. These results were attributed to the phenobarbital inducing N-hydroxylation related to the formation of the hemoglobin adduct. The N-acetylation ratio was only increased with the phenobarbital pretreatment due to the lower benzidine-HBI of the phenobarbital group compared to these of the control and ethanol groups. The N-acetylation ratios for all groups were higher than f for the duration of the experimental period. Although the azo reduction was unaffected by the ethanol, it was inhibited by the phenobarbital, The ratio of the benzidine-HBI in the phenobarbital group was lower than those of the ethanol the control groups for the entire experiment. Conclusion : Our results indicate that both ethanol and phenobarbital increase the formation of adducts by the induction of N-hydroxylation, but also induced N-acetylation. Phenobarbital decreased the formation of benzidine-HBI due to the decrease of the azo reduction. These results suggest that the effects or ethanol and phenobarbital need to be considered in the biochemical monitoring of Direct Black 38.

• Corrosion Science and Technology
• /
• 제13권1호
• /
• pp.20-27
• /
• 2014

The structures of reinforced concrete has been extensively increased with rapid development of industrial society. Futhermore, these reinforced concretes are easy to expose to severe corrosive environments such as sea water, contaminated water, acid rain and seashore etc.. Thus, corrosion problem of inner steel bar embedded in concrete is very important in terms of safety and economical point of view. In this study, multiple mortar test specimen(W/C:0.4) with six types having different cover thickness each other was prepared and was immerged in seawater solution for five years to evaluate the effect of cover thickness and immersion years to corrosion property of embedded steel bar. And the polarization characteristics of these embedded steel bars was investigated using electrochemical methods such as measuring corrosion potential, cathodic polarization curve, and cyclic voltammogram. At the beginning of immersion, the corrosion potentials exhibited increasingly nobler values with increasing cover thickness. However, after immersed for 5 years, the thicker cover of thickness, the corrosion potentials shifted in the negative direction, and the relationship between corrosion potential and cover thickness was not in good agreement with each other. Therefore, it is considered that the thinner cover of thickness, corrosive products deposited on the surface of the embedded steel bar plays the role as a resistance polarization which is resulted in decreasing the corrosion rate as well as shifting the corrosion potential in the positive direction. As a result, it seemed that the evaluation which corrosion possibility of the reinforced steel would be estimated by only measuring the corrosion potential may not be a completely desirable method. Therefore, it is suggested that we should take into account various parameters, including cover thickness, passed aged years as well as corrosion potential for more accurate assessment of corrosion possibility of reinforced steel which is exposed to partially or fully in marine environment for long years.

• Corrosion Science and Technology
• /
• 제13권1호
• /
• pp.28-35
• /
• 2014

Recently, the fuel oil of diesel engines of marine ships has been increasingly changed to heavy oil of low quality as the oil price is getting higher and higher. Therefore, the spiral gear attached at the motor of the oil purifier which plays an important role to purify the heavy oil is also easy to expose at severe environmental condition due to the purification of the heavy oil in higher temperature. Thus, the material of the spiral gear requires a better mechanical strength, wear and corrosion resistance. In this study, the heat treatment(tempering) with various holding time at temperature of $500^{\circ}C$ was carried out to the alloy of Cu-7Al-2.5Si as centrifugal casting, and the properties of both hardness and corrosion resistance with and without heat treatment were investigated with observation of the microstructure and with electrochemical methods, such as measurement of corrosion potential, cathodic and anodic polarization curves, cyclic voltammogram, and a.c. impedance. in natural seawater solution. The ${\alpha}$, ${\beta}^{\prime}$ and ${\gamma}_2$ phases were observed in the material in spite of no heat treatment due to quenching effect of a spin mold. However, their phases, that is, ${\beta}^{\prime}$ and ${\gamma}_2$ phases decreased gradually with increasing the holding time at a constant temperature of $500^{\circ}C$. The hardness more or less decreased with heat treatment, however its corrosion resistance was improved with the heat treatment. Furthermore, the longer holding time, the better corrosion resistance. In addition, when the holding time was 48hrs, its corrosion current density showed the lowest value. The pattern of corroded surface was nearly similar to that of the pitting corrosion, and this morphology was greatly observed in the case of no heat treatment. It is considered that ${\gamma}_2$ phase at the grain boundary was corroded preferentially as an anode. However, the pattern of general corrosion exhibited increasingly due to decreasing the ${\gamma}_2$ phase with heat treatment. Consequently, it is suggested that the corrosion resistance of Cu-7Al-2.5Si alloy can be improved with the heat treatment as a holding time for 48 hrs at $500^{\circ}C$.

• 대한치과보철학회지
• /
• 제31권3호
• /
• pp.423-446
• /
• 1993

Titanium and its alloys are finding increasing use in medical devices and dental implants. The strong selling point of titanium is its resistance to the highly corrosive body fluids in which an implant must survive. This corrosion resistance is due to a tenacious passive oxide or film which exists on the metal's surface and renders it passive. Potentiodynamic polarization measurement is one of the most commonly used electro-chemical methods that have been applied to measure corrosion rates. And the potentiodynamic polarization test supplies detailed information such as open circuit, rupture, and passivation potential. Furthermore, it indicates the passive range and sensitivity to pitting corrosion. This study was designed to compare the corrosion resistance of the commonly used dental implant materials such as CP Ti, Ti-6A1-4V, Co-Cr-Mo alloy, and 316L stainless steel. And the effects of galvanic couples between titanium and the dental alloys were assessed for their useful-ness-as. materials for superstructure. The working electrode is the specimen , the reference electrode is a saturated calomel electrode (SCE), and the counter electrode is made of carbon. In $N_2-saturated$ 0.9% NaCl solutions, the potential scanning was performed starting from -800mV (SCE) and the scan rate was 1 mV/sec. At least three different polarization measurements were carried out for each material on separate specimen. The galvanic corrosion measurements were conducted in the zero-shunt ammeter with an implant supraconstruction surface ratio of 1:1. The contact current density was recorded over a 24-hour period. The results were as follows : 1. In potential-time curve, all specimens became increasingly more noble after immersion in the test solution and reached between -70mV and 50mV (SCE) respectively after 12 hours. 2. The Ti and Ti alloy in the saline solution were most resistant to corrosion. They showed the typical passive behavior which was exhibited over the entire experimental range. Therefore no breakdown potentials were observed. 3. Comparing the rupture potentials, Ti and Ti alloy had the high(:st value (because their break-down potentials were not observed in this study potential range ) followed by Co-Cr-Mo alloy and stainless steel (316L). So , the corrosion resistance of titanium was cecellent, Co-Cr-Mo alloy slightly inferior and stainless steel (316L) much less. 4. The contact current density sinks faster than any other galvanic couple in the case of Ti/gold alloy. 5. Ag-Pd alloy coupled with Ti yielded high current density in the early stage. Furthermore, Ti became anodic. 6. Ti/Ni-Cr alloy showed a relatively high galvanic current and a tendency to increase.

• 자원리싸이클링
• /
• 제25권3호
• /
• pp.55-62
• /
• 2016

해양환경 및 공장지역과 같이 가혹한 부식환경에 놓인 강구조물은 사용수명을 증대시키기 위하여 다양한 방식 기술을 적용하여 건설되고 있다. 그 중 금속용사에 의한 방식기술은 일반적으로 널리 쓰이는 기술의 단점을 보완한 방식 기술이지만 완벽하다 할 수 없어 내식성 향상에 대한 연구개발이 절실한 상황이다. 본 연구에서는 금속용사에서 사용되는 금속 재료의 종류 및 용사 두께의 변화에 따른 내식성을 평가하였으며 전기화학적 방법인 부식전위 및 부식전류밀도 측정을 통하여 비교 고찰하였다. 금속용사 재료로는 아연(Zn) 및 알루미늄(Al)을 사용하여 비율을 조절하였고, 용사 두께는 $30{\sim}100{\mu}m$ 사이에서 구분하여 선정하였다. 검토 결과, 금속용사 재료로 Zn을 100% 사용한 경우에서 가장 낮은 부식전위가 측정된 것을 확인하였으며, Zn 85%-Al 15% 합금과 Al 100%의 경우에는 부식전류밀도가 감소하였다. 또한 용사재료에 관계없이 용사두께가 증가할수록 부식전위는 감소하였다.