• Current Applied Physics
• /
• 제18권11호
• /
• pp.1201-1204
• /
• 2018

The effect of electric current pulses on a sub-100 nm magnetic bubble state in a symmetric Pt/Co multilayer was directly observed using a full-field transmission soft X-ray microscope (MTXM). Field-induced evolution of the magnetic stripe domains into isolated bubbles with their sizes down to 100 nm was imaged under varying external magnetic fields. Electric current pulses were then applied to the created magnetic bubbles, and it was observed that the bubbles could be either created or annihilated by the current pulse depending on the strength of applied magnetic field. The results suggest that the Joule heating plays a critical role in the formation and/or elimination of the bubbles and skyrmions. Finally, the schematic phase diagram for the creation and annihilation of bubbles is presented, suggesting an optimized scheme with the combination of magnetic field and electric current necessary to utilize skyrmions in the practical devices.

• Journal of Electrochemical Science and Technology
• /
• 제12권1호
• /
• pp.21-32
• /
• 2021

This study reports for the first time the application of electrocoagulation (EC) from laboratory to pilot scales for the treatment of printing wastewater, a hazardous waste whose treatment and disposal are strictly regulated. The wastewater was taken from three real printing companies with strongly varying characteristics. The treatment process was performed in the laboratory for operational optimization and then applied in the pilot scale. The weight loss of the electrode and the generation of sludge at both scales were compared. The results show that the raw wastewater should be diluted before EC treatment if its COD is higher than about 10,000 mg/L. Pilot scale removal efficiencies of COD and color were slightly lower compared to those obtained from the laboratory scale. At pilot scale, the effluent CODs removal efficiency was 81.9 - 88.9% (final concentration of 448 - 992 mg/L) and color removal efficiency was 95.8 - 98.6% (final level of 89 - 202 Pt-Co) which proved the feasibility of EC treatment as an effective pre-treatment method for printing wastewater as well as other high colored and hard-biodegradable wastewaters.

• Journal of Electrochemical Science and Technology
• /
• 제14권1호
• /
• pp.15-20
• /
• 2023

Ionic liquids are considered as a promising, alternative solvent for the electrochemical synthesis of metals because of their high thermal and chemical stability, relatively high ionic conductivity, and wide electrochemical window. In particular, their wide electrochemical window enables the electrodeposition of metals without any side reaction of electrolytes such as hydrogen evolution. The electrodeposition of silver is conducted in 1-n-butyl-3-methylimidazolium chloride ([C4mim]Cl) ionic liquid system with a silver source of AgCl. This study is the first attempt to electrodeposit silver nanoparticles without using co-solvents other than [C4mim]Cl. Pulse electrolysis is employed for the synthesis of silver nanoparticles by varying applied potentials from -3.0 V to -4.5 V (vs. Pt-quasi reference electrode) and pulse duration from 0.1 s to 0.7 s. Accordingly, the silver nanoparticles whose size ranges from 15 nm to ~100 nm are obtained. The successful preparation of silver nanoparticles is demonstrated regardless of the kinds of substrate including aluminum, stainless steel, and carbon paper in the pulse electrolysis. Finally, the antimicrobial property of electrodeposited silver nanoparticles is confirmed by an antimicrobial test using Staphylococcus aureus.

• Annals of Clinical Neurophysiology
• /
• 제25권1호
• /
• pp.32-37
• /
• 2023

Background: Type 2 diabetic mellitus (T2DM) is an emerging global pandemic which is associated with lots of co-morbidities and reported vascular dysfunctions. T2DM associated vascular dysfunctions leads to vasculopathy in the form of altered peripheral vascular dynamics. Cold stress test (CST) is a reliable sympathetic reactivity test used for assessing vascular dysfunctions. In this study we are trying to quantify vascular dysfunctions in T2DM patients non invasively by various parameters of photoplethysmography (PPG) of cold stress test. Methods: Case control study had done in referral health center AIIMS, Raipur. Parameters are recorded by finger-PPG before, during and after CST (1 min) in 2 groups, control (n = 20 healthy volunteers) and case (n = 20 diagnosed T2DM patients). Results: Due to cold stress, PPG parameter peak amplitude was significantly decreased in both healthy and T2DM groups (p <0.001 and p <0.001, respectively). However, recovery trend of amplitude was significantly slow in T2DM compared to healthy subjects. Another PPG parameter peak to peak interval was significantly higher in healthy group compared to T2DM patients. Conclusions: This study showed that T2DM patients has significant deranged pulse volume parameters like amplitude and peak to peak interval can be used to objectively quantify the vasculopathy in T2DM patients by using sympathetic reactivity to cold stress.

• 한국분말재료학회지
• /
• 제30권2호
• /
• pp.156-168
• /
• 2023

The semiconductor industry faces physical limitations due to its top-down manufacturing processes. High cost of EUV equipment, time loss during tens or hundreds of photolithography steps, overlay, etch process errors, and contamination issues owing to photolithography still exist and may become more serious with the miniaturization of semiconductor devices. Therefore, a bottom-up approach is required to overcome these issues. The key technology that enables bottom-up semiconductor manufacturing is area-selective atomic layer deposition (ASALD). Here, various ASALD processes for elemental metals, such as Co, Cu, Ir, Ni, Pt, and Ru, are reviewed. Surface treatments using chemical species, such as self-assembled monolayers and small-molecule inhibitors, to control the hydrophilicity of the surface have been introduced. Finally, we discuss the future applications of metal ASALD processes.

• Journal of Electrochemical Science and Technology
• /
• 제15권2호
• /
• pp.207-219
• /
• 2024

Metal-N-C (MNC) catalysts have been anticipated as promising candidates for oxygen reduction reaction (ORR) to achieve low-cost polymer electrolyte membrane fuel cells. The structure of the M-N_x moiety enabled a high catalytic activity that was not observed in previously reported transition metal nanoparticle-based catalysts. Despite progress in non-precious metal catalysts, the low density of active sites of MNCs, which resulted in lower single-cell performance than Pt/C, needs to be resolved for practical application. This review focused on the recent studies and methodologies aimed to overcome these limitations and develop an inexpensive catalyst with excellent activity and durability in an alkaline environment. It included the possibility of non-precious metals as active materials for ORR catalysts, starting from Co phthalocyanine as ORR catalyst and the development of methodologies (e.g., metal-coordinated N-containing polymers, metal-organic frameworks) to form active sites, M-N_x moieties. Thereafter, the motivation, procedures, and progress of the latest research on the design of catalyst morphology for improved mass transport ability and active site engineering that allowed the promoted ORR kinetics were discussed.

• 센서학회지
• /
• 제7권3호
• /
• pp.188-196
• /
• 1998

$WO_{3}$계 n-형 반도체 가스센서의 검지특성 및 전기적 특성을 조사하였다. 공기중에서 결합제가 첨가되지 않은 $WO_{3}:TiO_{2}$(4 wt. %) 센서의 낱알경계에서의 전위장벽의 크기는 0.26 V로 나타났으며, 결합제로서 $Al_{2}O_{3}$, PVA (polyvinyl alcohol ), silica sol이 첨가된 센서의 경우는 전위장벽이 각각 0.17, 0.22, 0.26 V로 관측되었다. 이들 시료를 $NO_{x}$가 120 ppm 첨가된 분위기에 노출시켰을 때, 결합제가 첨가되지 않은 센서의 경우는 낱알경계에서의 전위장벽이 0.59 V로 증가하였으며, 결합제로서 $Al_{2}O_{3}$, PVA, silica sol이 첨가된 경우는 전위장벽이 각각 0.43, 0.66, 0.52 V로 나타나, PVA가 첨가된 센서에서 전위장벽의 변화가 가장 높아 감도가 우수하게 되는 것을 알 수가 있었다. 한편 센서 최적 작동온도 이상의 온도에서 나타나는 감도의 감소는 흡착가스 입자의 탈착보다는 공기중에서 다결정이 보이는 저항의 온도 의존성에 따라 나타남이 판명되었다. 또한 결합제가 첨가되지 않은 센서와 결합제로서 Pt가 첨가된 센서의 경우, CO가 250 ppm 존재할 때까지도 전위장벽의 크기가 약 0.2 V로 공기중에서와 비슷한 크기를 나타내어, CO와 $NO_{x}$가 혼합된 분위기에서 $NO_{x}$만을 선택적으로 검지하는데 유리함이 밝혀졌다.

• 청정기술
• /
• 제14권1호
• /
• pp.61-68
• /
• 2008

연료전지기술은 환경적으로 유해한 오염물질을 발생시키지 않으려, 높은 에너지 밀도를 가지는 청정에너지기술이다. 특히 고분자전해질 연료전지(Polymer electrolyte membrane fuel cell, PEMFC)는 넓은 응용분야로 인해 최근 큰 관심을 받고 있으며, 폭넓은 연구가 진행되고 있다. 본 연구에서는 단위전지 내 연료극(anode) 및 공기극(cathode) 촉매 층을 대상으로 고분자전해질연료전지의 운전시간 경과에 대한 성능변화 및 안정성을 예측하는 모델링을 수행하였다 촉매층에서 발생하는 단위전지의 주요한 성능감소 원인으로 연료극에서의 일산화탄소 피독 현상을 고려하였다. 전지의 장기간 운전모델링 결과 연료극에 공급되는 기체 내의 일산화탄소 비율이 클수록 단위전지성능의 안정성이 크게 감소되는 것으로 나타났다. 또한 장기 운전시 공기극의 느린 산소환원반응과 백금의 용해와 소결에 의해 전지의 성능이 감소되는 것으로 나타났다. 이들을 극복하는 방안으로 연료극에 공급되는 수소의 비율을 높이고 공기극의 촉매층 내에 있는 백금양을 높이는 것을 제안하고자 한다.

• Clinical and Experimental Pediatrics
• /
• 제45권12호
• /
• pp.1512-1518
• /
• 2002

목 적 : 쌍태 임신에서 일측 태아가 자궁내 사망한 경우 생존아의 사망률이 높고 범발성 혈관내 응고병증, 패혈증 및 뇌손상 등을 증가시킨다고 알려져 있다. 본 연구는 일측 태아의 자궁내 사망 후 생존아들의 주산기 합병증 및 이와 연관된 위험 인자들에 대해 알아보고자 하였다. 방 법 : 1995년 1월부터 2000년 12월까지 쌍태 임신 중 일측 태아가 자궁내 사망한 후 생존 출생한 15례의 의무 기록지를 후향적으로 분석하였다. 생존아에서는 말초 혈액과 혈액 응고계 검사, 두부 초음파 및 뇌 자기공영상 검사를, 그리고 산모에서는 말초 혈액과 혈액 응고계 검사 및 임신과 관련된 합병증에 대해 의무 기록지를 통하여 후향적으로 조사하였고, 생존아에서 주산기 합병증에 대한 위험 인자로 융모막 상태, 출생 체중, 재태 주령 및 일측 태아의 자궁내 사망 후 분만까지의 기간에 대해 관찰하였다. 결 과 : 1) 일측 태아의 자궁내 사망 후 생존 출생아 15례의 재태 주령은 $33.7{\pm}3.2$주, 출생 체중은 $1,992{\pm}592g$, 분만까지의 기간은 $32.4{\pm}29.5$일이었고, 조산아 11례(73.3%), 만삭아 4례(26.7%)로 조산의 원인은 조기 진통과 조기 양막 파수가 주였다. 2) 산모에서 시행한 혈액 검사상 범발성 혈관내 응고병증은 1례도 없었고, 산모의 말초 혈액 검사(백혈구수, 혈소판수, PT, aPTT, fibrongen, FDP) 소견과 생존아의 범발성 혈관내 응고병증 및 뇌연화증 발생과는 연관이 없었다. 3) 생존아 총 15례 중 6례(40.0%)는 정상이었고, 범발성 혈관내 응고병증 3례(20.0%), 뇌연화증 3례(20.0%), 자궁내 발육 지연 1례, 쌍태아간 수혈 증후군(recepient) 1례, 선천성 심장기형(심방 중격 결손 및 폐동맥 협착)이 동반된 경우 1례 있었다. 4) 생존 출생아에서 범발성 혈관내 응고장애 및 뇌연화증의 발생은 융모막 상태, 출생 체중, 재태 주령 및 일측 태아의 자궁내 사망 후 생존아 분만까지의 기간과 통계학적 유의성이 없었다. 결 론 : 본 연구에서는 자궁내에서 일측 태아가 사망한 경우 산모에서 혈액학적 이상은 발견할 수 없었고 생존아에서 주산기 합병증을 예측할 수 있는 의의 있는 위험 인자를 발견할 수 없었지만 약 20.0%에서 뇌연화증 및 범발성 혈관내 응고병증이 발생하였기에 쌍태 임신 중 임신 제2, 3기에 일측 태아가 자궁내 사망한 경우 생존 출생아에 대한 면밀한 혈액학적 및 신경학적 검사가 필요하다고 사료되었다.

• 한국수소및신에너지학회논문집
• /
• 제24권5호
• /
• pp.359-366
• /
• 2013

This work is investigated for the catalytic decomposition of hydrogen iodide (HI). Platinum was used as active material by loading on $ZrO_2-SiO_2$ mixed oxide in HI decomposition reaction. To obtain high and stable conversion of hydrogen iodide in severe condition, it was required to improve catalytic activity. For this reason, a method increasing dispersion of platinum was proposed in this study. In order to get high dispersion of platinum, zirconia was incorporated in silica by sol-gel synthesis. Incorporating zirconia influence increasing platinum dispersion and BET surface area as well as decreasing deactivation of catalysts. It should be able to stably product hydrogen for a long time because of inhibitive deactivation. HI decomposition reaction was carried out under the condition of $450^{\circ}C$ and 1 atm in a fixed bed reactor. Catalysts analysis methods such as $N_2$ adsorption/desorption analysis, X-ray diffraction, X-ray fluorescence, ICP-AES and CO gas chemisorption were used to measurement of their physico-chemical properties.