Influence of Phase Composition in TiAlSiN Hard Coatings on the Evolution of Structure and Mechanical Properties

Jeong‑Han Lee,Ik‑Hyun Oh,Jun‑Ho Jang,Ju‑Hun Kim,Sung‑Kil Hong,Hyun‑Kuk Park 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.3

The aim of this study is to investigate the structural evolution and mechanical properties of TiAlSiN coatings when processedby the arc ion plating method. To form a hard coating, Ti, Al, and Si powders were mechanically alloyed by planetary ballmilling; the powders were then densely compacted during a rapid sintering process into a ternary system coating, i.e. TiAlSi. The evolution of the structural phase from a powder to a compact material is dominated considerably by phase states suchas a supersaturated solid solution or intermetallic compounds. In the case of coating layers, the factors that determine thestructural evolution are associated with the phase stability of the nano-crystalline structure that in turn is associated withthe Ti/Al composition ratio. Motivated by this, we performed experiments to investigate the distribution of microstructures;the material’s binding energy, quantitative properties, transformation of crystal structure, and distribution of amorphous/crystalline were all recorded. In particular, the relationship between the physical and chemical properties during the coatingprocess is considered to be the dominant factor controlling the orientation and morphology of that zone (1, T, and 2). TheTiAlSiN coating layer was found to have hardness above 45 GPa and an adhesion above 100 N. In other words, understandingthe evolution and structure of TiAlSin helped us to produce a material with excellent properties that can be used as a hardcoating. Specifically, these properties were induced by a grain refinement of the nano-crystalline structure that correspondsto an increase in the silicon nitride contents.

Preparation of mechanically enhanced supramolecular carbon nanotube (CNT) film using a water‑soluble π–π bonding linker

Jun‑Woo Lee,Moonseong Yoo,Kun Won Kim,Hyein Jeong,Jae Woo Chung 한국탄소학회 2019 Carbon Letters Vol.29 No.5

Mechanically enhanced supramolecular carbon nanotube (CNT) films were prepared in water by employing the π-electronrich phenyl, naphthalenyl, and pyrenyl end-functionalized polyethylene oxides (PEOs) as supramolecular linkers, followed by vacuum filtration. Among them, the supramolecular CNT film produced by the pyrenyl end-functionalized PEO (PEOPy) exhibited the highest mechanical strength, which was ~ 1.5–2 times higher than that of the CNT films produced using the typical dispersant, Triton X-100, although the functionality of PEO-Py was lower than that prepared using other linkers, and the content of PEO-Py in the CNT films was lower than that obtained using Triton X-100. Fluorescence and UV–Vis spectroscopy demonstrated that the improved mechanical properties of the supramolecular CNT film result from the formation of π–π interactions between the CNT and the pyrene moieties of the PEO-Py linker. Finally, the supramolecular CNT film exhibited a 40–50 dB electromagnetic shielding efficiency through hybridization with silver nanowires.

Effect of Mechanical Alloying on the Microstructural Evolution of Al60Cr30Si10 Alloys Processed by Spark Plasma Sintering

Jeong‑Han Lee,Ik‑Hyun Oh,Jun‑Ho Jang,Ju‑Hun Kim,Sung‑Kil Hong,Hyun‑Kuk Park 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.5

In this study, Al, Cr and Si fine powders were alloyed by planetary ball milling to investigate their microstructural evolution,following their mechanical alloying behavior. The formation of Al(Cr) supersaturated solid solution by the Cr grainsembedded in Al-matrix, which contributed substitutional structure is discussed in relation to their structural evolution inaccordance with the distortion of a crystal lattice. The compacts of Al–Cr–Si alloys were prepared by rapid sintering withina short time by dense consolidation above the density of 99.9% as the formation of intermetallics, except in the case of thedistribution of single-phases induced by the Al-melting. The formation behavior of intermetallics was dominated by dependenceon the structures of the milled-powder and subsequent sintering temperature. To estimate the consolidated behaviorsof compacts, various approaches derived from TEM and XRD analysis were taken to obtain microstructural evidences ofthe inter-diffusion, following the presence of thermally stable intermetallics.

대장암종에서 암관련 유전자들의 Promoter Methylation과 암종 발생 및 진행과의 관게에 대한 연구

정동준,이정은,민영기,조성우,백무준,양승하,김의한,김창진 순천향대학교 교수학습개발센터 2004 Journal of Soonchunhyang Medical Science Vol.10 No.3

The colorectal corcinoma is one of the most common malignant tumor in Korea and its carcinogenic mechanism has not been elucidated exactly yet. So far, the most common carcinogenic mechanism has been known to be multiple genetic changes. But, the CpG island hypermethylation has been revealed to be one of the most important carcinogenic mechanism second to the genetic changes. The epigenetic changes characteristically imprint and transfer to the next generation without changes of nucleotide sequences. When the CpG island of promoter or 5'- exon 1 of a specific gene is methylated by DNA methyltrasferases (DNMTs), the gene expression is inhibited. Carcinogenic mechansisms by promoter methylation has been well known, but the progression of the cancer has not been elucidated yet. The molecular researches on the carcinogenic mechanisms largely depended on the tumor tissue containing various components of cell, due to difficulties in harvesting pure homogeneous tumor cells. Promoter methylatonof the cancer related genes as APc, hMLH2, p16, DAP-K and MGMT in 50 cases of sporadic colorectal carcinoma was studied. The pure normal colorectal epithelial cells, and cancer cells from superficial and deep invasive portion were harvested respectively by laser captured microdissection(LCM), and DNA was extracted from them. The promoter methylation was studied by methylation specific poymerase reaction (MSP) after bisulfite modification of the DNA and the expression of the genes by immunohistochemistry. The results suggests that promoter methylation of the cancer related genes are closely related with the colorectal carcinogenesis and it occurrs from early phase of carcinogenesis, progressing constantly to the late stage. And the promoter methylation of normal epithelial cells increased by age. The p15, known to be the genes related to hematologic malignancy, was closely related to the colorectal carcinoma as well.

3차 병원의 병동에서 시행된 심폐소생술의 분석

류진호,정경운,위준선,문정미,전병조,문원식,김용권,소정일,허탁,민용일 대한응급의학회 2001 대한응급의학회지 Vol.12 No.4

Background: Although cardiopulmonary resuscitation(CPR) is a very effective therapy in cardiac arrest, it is hard to prove the true effectiveness of CPR. Several studies about out-of-hospital and emergency department CPR exist, but only a few reports about in-hospital CPR are available. This study was designed to investigate in-hospital cardiac arrest, to analyze the result of CPR, and to evaluate the problems associated with in-hospital CPR. Methods: A clinical analysis of 71 cases of in-hospital CPR announcement from January 2000 to August 2000 was performed. The initial rhythm on cardiac arrest, return of spontaneous circulation(ROSC), and the survivals were analyzed in the case of the 46 true cardiac arrest patients. Results: During 8 months, there were 71 cases of in-hospital CPR announcement. Among them, there were 46 cases of true cardiac arrest and 25 cases of non-cardiac arrest. Of the 46 true cardiac-arrest cases, 27(58.7%) experienced ROSC, 15(32.6) survived for over 24 hours, and 7(15.2%) survived to be discharged. The initial rhythms on cardiac arrest were 30 cases(65.2%) of asystole, 14(30.4%) of PEA(pulseless electrical activity), and 2(4.3%) of ventricular fibrillation, with ROSC being 17 cases(56.7%), 9(64.3%) and 1(50.0%) cases and discharged survivors being 4 cases(13.3%), 3(21.4%) and 0(0.0%) cases, respectively. Conclusion: Extraordinarily high proportions of asystole and PEA were seen in the initial rhythm of cardiac arrest, and those were associated with high survival rates. Although further study is needed to evaluate the course leading to this high proportion of asystole and PEA, this result suggests that if the EMS system in the hospital is activated promptly and systematically, a better outcome will be achieved in case of cardiac arrest with asystole and PEA.

개에서 이중 결찰법을 통한 동맥관 개존증의 완치 예

윤헌영,정순욱,박희명,박철,정만복,김준영,한현정,황민,노병국,박상혁,장하영,박정윤 한국임상수의학회 2004 한국임상수의학회지 Vol.21 No.1

A ten months old, female Yorkshire terrier weighing 2.88 kg referred to veterinary teaching hospital of college of veterinary medicine, Konkuk University because of syncope, cough and dyspnea. First hematological and serum chemical test revealed thrombocytopenia, mild anemia, and increase of concentration of ALP (195 U/L). On 57 days later, second hematological and serum chemical test revealed polycythemia, increase of concentration of ALP (211 U/L), and Tchol (387 mg/dl). Right atrium enlargement, main pulmonary artery bulge and cardiomegaly (VHS = 11.5) were observed in radiographic findings. Ultrasonographic images showed both right and left ventricular dilation and turbulent flow between the descending aorta and the main pulmonary artery in color Doppler imaging. ECG showed left ventricular enlargement, SA block, and electrical alternant. Thoracotomy was performed through left fourth intercostal incision under isoflurane anesthesia. Patent ductus arteriosus was double ligated with 1-0 silk. Cough and dyspnea disappeared on 5 days after operation. Turbulent flow was not found in color doppler imaging of ultrasonography on 10 days after operation. Ten months later after the operation, syncope could not exist any more.

응급실에 내원한 환자에서 어지럼증의 원인과 임상양상의 분석

문원식,정경운,위준선,문정미,전병조,김용권,소정일,류진호,허탁,민용일 대한응급의학회 2001 대한응급의학회지 Vol.12 No.3

Background: Recently, The number of patients who have been complaining of the vertigo or dizziness has been increasing due to rapid growth of elderly population and senile disease. The differentiation of dizzy patients is not familiar to most emergency physicians. This study was designed to differentiate true vertigo and to investigate the clinical difference among central vertigo, peripheral vertigo, and other causes of dizziness. Methods: The authors analyzed the cases of 237 dizzy patients who visited the emergency department of Chonnam University Hospital during the recent 2 years. For the base of dizziness, associated past illnesses, severity, nystagmus type, and the causes of central and peripheral vertigo. Results: Female patients were 142(59.9%) and male patients were 95(40.1%). The most common age group was the 6th decade. The origin of dizziness was classified as peripheral cause(25.3%), central cause(32.9%), and others(41.8%). As to nature of the dizziness, the rotatory sense was dominant in peripheral vertigo and the floating sense and blurred vision in central vertigo. Peripheral vertigo was triggered by position change of head and body, and central vertigo by the eye movement. Audiograms I showed that most patients with central vertigo had normal hearing, but 46.7% of thoswith peripheral vertigo had an abnormal hearing disturbance. Nystagmus was more prevalent in peripheral vertigo Conclusion: History taking and physical examination played an important role in the diagnosis of dizzy patients. An important part of the diagnosis of a dizzy patient could be to evaluate the peripheral origin, the central origin and others causes. Because central vertigo may be associated with a significant neurological pathology, spectral radiological studies, including MRI and CT, are mandatory to rule out a devastating brain lesion.

대동맥 협착증과 동반된 출혈성 위장관 동정맥 기형에서 Estrogen-Progesterone 치료 1예

김도연,김화정,김효정,남준식,박수영,박영미,신정은,주미순,황민규,정혜경,손혜영,이선영,이한주 大韓消化器內視鏡學會 1999 Clinical Endoscopy Vol.19 No.부록2

혈액 투석 환자에서 중심정맥 협착에 대한 스텐트 삽입술 : Wallstent Placement

임대승,노상필,이유선,정승현,김보영,이정우,강정아,김정희,이민수,정준용,최시완,정진옥,성인환,이강욱,신영태 충남대학교 의과대학 의학연구소 2002 충남의대잡지 Vol.29 No.1

Stenosis of central vein is a common complication arising after percutaneous subclavian vein catheter insertion performed for temporary vascular access in chronic renal failure patients undergoing hemodialysis. There are several treatment methods for the condition like percutaneous angioplasty(PTA), stent insertion, and surgery, but recent trend is toward PTA and stents. Among the patients diagnosed with chronic renal failure from March 1993 to May 2002 and undergoing hemodialysis through AV fistula, the 14 Patients in whom central vein stenosis arose were selected for the study. A total of 28 percutaneous interventions(5 PTA and 23 stent placement) were performed, and restenosis rate and the time taken till the restenosis in de novo lesions and instant lesions were compared. All 28 cases were operated successfully. The 14 cases that received both anigioplasty and stent placement initially. (de novo lesion : 14 cases), Among the 10 cases with de novo lesion that followed up more than 1 year, 3 cases are currently undergoing hemodialysis without restenosis, and the remaining 7 cases have recurred stenosis with the mean time to restenosis of 10.9 months. In the 7 cases in whom stenosis recurred, 11 interventions were done(instent lesion: 11 cases). 4 of these were using only ballon angioplasty with 100% restenosis rate and the mean time of 3 months until restenosis. The remaining 7 cases were using both balloon angioplasty and stent placement, also with 100% restenosis rate but with the mean time of 12 months until restenosis, which was later than the group receiving only balloon angioplasty. In treating the patients with central vein stenosis, stent placement seems to be more advantageous over PTA in terms of restenosis rate and the mean duration of patency. In the case of instent lesion, inserting the stent for the second time after stenosis recurred lengthened the duration of patency compared to performing balloon angioplasty alone.

Carnosine Promotes Exhaustive Swimming Capacity in Mice

Jong-Soo Kim, Ki Nam Lee, Jin-Joo Hue, Jun-Hyeong Kim, Bong Soo Kang, Sang Yoon Nam, Young Won Yun, Jae-Hwang Jeong2, Beom Jun Lee 충북대학교 동물의학연구소 2011 Journal of Biomedical and Translational Research Vol.12 No.1

To investigate the effect of carnosine on exhaustive exercise, swimming tests were conducted weekly with loads corresponding to 5% of body weight attached to the tails of mice, and the swimming time to exhaustion was measured. Eighty male ICR mice were divided into four groups, to which carnosine was administered at doses of 0 (control), 10, 50, and 250 mg/kg/day, respectively, for a period of four weeks. At the end of swimming exercise challenges, serum biochemistry, oxidative stress enzyme activity, and antioxidant enzyme activity in tissues were determined. Treatment with 250 mg/kg carnosine resulted in a significant increase in swimming times to exhaustion, compared to the control group in the first (P<0.01) and third week (P<0.05). Significantly lower serum lactate levels were observed after the swimming exercise in the carnosine-treated groups (10 and 250 mg/kg), compared with the control (P<0.01). Malondialdehyde levels in the liver (10 and 50 mg/kg carnosine treated groups) and skeletal muscle (250 mg/kg carnosine treated group) were significantly lower, compared with the control (P<0.05). Significantly lower protein carbonyl levels in skeletal muscle were observed in the 50 and 250 mg/kg carnosine treated groups, compared with the control (P<0.01). Superoxide dismutase and glutathione peroxidase activities in skeletal muscle did not differ significantly among the groups. These results indicate that carnosine may improve swimming exercise capacity by attenuating production of lactate and reducing oxidative stress in mice.