Effect of spark plasma sintering conditions on the thermoelectric properties of (Bi_0.25Sb_0.75)₂Te₃ alloys

Lim, Sang-Soon,Kim, Ju-Heon,Kwon, Beomjin,Kim, Seong Keun,Park, Hyung-Ho,Lee, Ki-Suk,Baik, Jeong Min,Choi, Won Jun,Kim, Dong-Ik,Hyun, Dow-Bin,Kim, Jin-Sang,Baek, Seung-Hyub Elsevier 2016 JOURNAL OF ALLOYS AND COMPOUNDS Vol.678 No.-

<P><B>Abstract</B></P> <P>As a field-assisted technique, spark plasma sintering (SPS) enables densification of specimens in a very short period of time compared to other sintering techniques. For high performance thermoelectric material synthesis, SPS is widely used to fabricate nanograin-structured thermoelectric materials by rapidly densifying the nanopowders suppressing grain growth. However, the microstructural evolution behavior of thermoelectric materials by SPS, another important process during sintering, has been rarely studied. Here, we explore SPS as a tool to control the microstructure by long-time SPS. Using p-type (Bi<SUB>0.25</SUB>Sb<SUB>0.75</SUB>)<SUB>2</SUB>Te<SUB>3</SUB> thermoelectric materials as a model system, we systematically vary SPS temperature and time to understand the correlations between SPS conditions, microstructural evolution, and the thermoelectric properties. Our results show that the relatively low eutectic temperature (∼420 °C) and the existence of volatile tellurium (Te) are critical factors to determine both microstructure and thermoelectric property. In the liquid-phase sintering regime, rapid evaporation of Te leads to a strong dependence of thermoelectric property on SPS time. On the other hand, in the solid-phase sintering regime, there is a weak dependence on SPS time. The optimum thermoelectric figure-of-merit (Z) of 2.93 × 10<SUP>−3</SUP>/K is achieved by SPS at 500 °C for 30 min. Our results will provide an insight on the optimization of SPS conditions for materials containing volatile elements with low eutectic temperature.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Spark plasma sintering (SPS) is used to synthesize the thermoelectric (Bi<SUB>0.25</SUB>Sb<SUB>0.75</SUB>)<SUB>2</SUB>Te<SUB>3</SUB>. </LI> <LI> Liquid phase and volatile element are a key for the microstructure and thermoelectric property. </LI> <LI> Thermoelectric figure-of-merit of 2.9 × 10<SUP>−3</SUP>/K is achieved at 500 °C for 30 min. </LI> </UL> </P>

Improving Upper Limb Spasticity in Patients with Stroke by Electroacupuncture Therapy: a Pre- and Post-Treatment Study

Lim Sung Min,Go Eunji,Lee Jungsup,Lee Go Eun,Kim Eun Joo,Son Chihyoung 사단법인약침학회 2023 Journal of Acupuncture & Meridian Studies Vol.16 No.6

Background: Post-stroke upper limb spasticity (PS-ULS) causes a decline in the quality of life of patients by reducing their ability to perform normal daily activities. Objectives: We performed pre- and post-treatment analyses of the changes in stroke patients with ULS following constant electroacupuncture therapy (EAT). Methods: Thirty patients with PS-ULS underwent 12 sessions of EAT over 4 weeks. After performing acupuncture therapy at four acupoints on the affected arm (LI11, LI10, LI4, and TE5), electrostimulation (60 Hz) was performed for 20 min. The modified Ashworth scale (MAS) and the Fugl–Meyer assessment of the upper extremity (FMA-UE) were measured as the outcome variables. Results: Following EAT, there was a significant decrease in the elbow MAS score (p < 0.001), a significant decrease in the wrist MAS score (p < 0.01), and a significant increase in the FMA-UE score (p < 0.001). Adverse events related to EAT were not reported. Conclusion: EAT decreased upper limb spasticity and improved functional recovery at the elbow and wrist. Large-scale and rigorous clinical trials are needed to verify the efficacy of EAT.

보문 : 항고혈압성 안지오텐신 전환효소 저해제를 생산하는 새로운 효모의 선별 및 저해물질 최적 생산조건

강민구 ( Min Gu Kang ),김하근 ( Ha Kun Kim ),이성훈 ( Sung Hun Yi ),임성일 ( Sung Il Lim ),이종수 ( Jong Soo Lee ) 한국균학회 2011 韓國菌學會誌 Vol.39 No.3

Forty eight strains of yeast were cultured in potato dextorse(PD) broth at 30˚C for 24 hr and centrifuged with 12,000 rpm for 20 min. After concentrated the cultures, antihypertensive angiotensin I-converting enzyme(ACE) inhibitory activities of its concentrates were investigated. Among them, the concentrates from Saccharomyces cerevisiae Y183-3 showed the highest ACE inhibitory activity of 71.8%. The ACE inhibitor from Saccharomyces cerevisiae Y183-3 was maximally produced when Saccharomyces cerevisiae Y183-3 cultured in PD broth at 30˚C for 36 hr.

COPA(cuffed oropharyngeal airway)를 이용한 마취 유도 시 근이완제 사용 유무에 따른 반응

김상태,배진호,김상범,임승운,민병상,신영덕 대한마취과학회 2000 Korean Journal of Anesthesiology Vol.38 No.3

Background : COPA (cuffed oropharyngeal airway) is a convenient device for airway management in patients undergoing general anesthesia for elective surgery in supine position. It causes less pharyngeal trauma than LMA(Laryngeal mask airway). The purpose of this study was to compare the effect of COPA with and without muscle relaxant. Methods : Forty patients with ASA physical status I and II for elective surgery were randomly assigned to two groups. Anaesthesia was induced with propofol (2 mg/kg) and vecuronium (1.5 mg/kg) and was administered intravenously in Group I but not in Group II. Mask ventilation was done for 5 min with 0: 5 L/min. COPA was placed and heart rate, and systolic, mean, diastolic blood pressure and peak inspiratory pressure were measured at 1 min interval for 5 min. Anaesthesia was maintained with pro- pofol 150 ㎍/kg/min, fentanyl 1 ㎍/kg/hr, O_2 2 L/min and N_2O 2 L/min. Results : There were no significant differences between Group I and Group II in heart rate, systolic, mean and dstolic blood pressure. PIP (Peak inspiratory pressure) was increased and hiccups occurred significantly (p $lt; 0.05) in Group II. Complete airway obstruction occurred in one patient of Group I and severe coughing, body movements and gagging occurred during induction and insertion in Group II. conclusions : With the use of appropriate muscle relaxant, we can use COPA without increased inspiratory pressure or significant complication. (Korean J Anesthesiol 2000; 38: 399~403)

친환경 세척제의 처리 방법을 달리하여 착즙한 당근 주스의 미생물 안전성 및 품질

임상욱(Sang-Wook Lim),최다정(Da-Jeong Choe),강민정(Min-Jung Kang),김종현(Jong-Hyun Kim),김묘정(Myo-Jeong Kim),김민주(Min-Ju Kim) 한국식품영양과학회 2017 한국식품영양과학회지 Vol.46 No.10

본 연구에서는 당근의 세척에 사용되는 친환경 세척제의 초기 미생물 제어 효과를 향상시키기 위해 탄산수소나트륨과 구연산의 단독 및 병합 처리 조건을 설정하였으며 저장 중 당근 주스의 미생물 수 및 품질 특성 변화를 분석하였다. 친환경 세척제의 단독 처리 방법으로는 0.5, 1, 2% 탄산나트륨수와 0.2, 0.5, 1% 구연산수를 적용하였고, 살균 효과를 비교하기 위해 무처리구, 수돗물 처리구, 50 ppm 차아염소산나트륨 처리구를 사용하였다. 당근의 세척을 위한 병합처리 방법으로는 단독 처리에서 우수한 살균 효과를 나타낸 1% 탄산수소나트륨수와 1% 구연산수를 이용하였고, 1% 탄산수소나트륨수 처리 후 1% 구연산수로 처리하는 단계적 병합 처리구가 가장 우수한 살균 효과를 나타내었다. 1% 탄산수소나트륨수와 1% 구연산수의 단계적 병합 처리구는 무처리구에 비해 일반 세균수 1.87 log CFU/mL, 대장균군 1.56 log CFU/mL를 감소시켰고, 50 ppm 차아염소산수에 비해서도 일반 세균수 1.07 log CFU/mL, 대장균군 0.22 log CFU/mL의 미생물 감균효과를 나타냈다. 1% 탄산수소나트륨수 처리 후 1% 구연산수의 단계적 병합 처리구를 4°C에서 7일 동안 저장한 결과 수돗물, 50 ppm 차아염소산수나 혼합 병합 처리구, 1% 구연산수 처리 후 1% 탄산수소나트륨 처리구에 비해 미생물 제어 효과가 확실하게 나타났지만, pH, 당도, 산도, 색도에는 유의적인 차이가 나타나지 않았다. 본 연구 결과 1% 탄산수소나트륨과 1% 구연산의 단계적 병합 처리는 당근 세척 시 초기 미생물 제어와 품질 유지에 있어 효과적인 살균처리 방법으로 비가열 당근 주스의 유통기간 동안 미생물 안전기준에 부합하며 주스의 품질을 유지할 수 있는 바람직한 세척방법으로 판단된다. The aim of this study was to evaluate the microbial inhibitory activity and physicochemical quality of fresh carrot juice prepared with different environmentally-friendly washing methods during low temperature storage. Individual and combined treatments with sodium bicarbonate (baking soda, NaHCO₃) and citric acid were applied to carrots for 10 min. Tap water and 50 ppm of sodium hypochlorite (NaOCl) were used as the control. Combined treatment of 1% NaHCO₃ and 1% citric acid significantly reduced total aerobic counts and coliforms. In addition, combined treatment of 1% NaHCO₃ and 1% citric acid inhibited microbial growth for 7 days at 4°C and 10°C in a shelf-life study. There were no significant differences among the sanitizers in terms of °Brix, acidity, pH, and color. Changes in physicochemical quality were not significantly different by sanitizer but were affected by storage temperature. These results indicate that washing with combined treatment of 1% NaHCO₃ and 1% citric acid is an effective method to inhibit the microbial population and maintain physicochemical quality. Therefore, combined treatment of 1% NaHCO₃ and 1% citric acid can be effectively used to sanitize and prepare carrot juice without affecting other properties.

세 개의 히드록실기를 가진 양이온 계면활성제 합성 및 계면 특성에 관한 연구

이병민 ( Byung Min Lee ),김지현 ( Ji Hyun Kim ),김승수 ( Sung Soo Kim ),임종주 ( Jong Choo Lim ) 한국공업화학회 2012 공업화학 Vol.23 No.5

본 연구에서는 도데실 글리시딜 에테르와 아미노에탄올을 반응시킨 후 디메틸 설페이트로 4급화시켜 분자 내에 2개의 라우릴기, 3개의 히드록실기를 가진 양이온 계면활성제 BHMAS (N, N-bis-(3`-n-dodecyloxy-2`-hydroxypropyl)-N-methyl- 2-hydroxyethylammonium methyl sulfate)를 합성하였고, 생성물의 분자구조는 1 H-NMR, FT-IR 등의 기기분석을 통하여 확인하였다. 합성한 계면활성제의 CMC (critical micelle concentration)는 9.12 × 10 -4 mol/L이며, CMC에서의 표면장력은 28.71mN/m이었다. Maximum bubble pressure tensiometer를 사용하여 동적 표면장력을 측정한 결과, 공기와 수용액의 계면이 계면활성제 단분자에 의하여 포화되는 데 비교적 오랜 시간이 소요되었다. 1 wt% 계면활성제 수용액과 n-decane 사이의 계면장력은 0.045mN/m이며, 평형에 도달하는 데 약 5 min의 시간이 소요되었다. 합성된 계면활성제의 흡착 특성이 매우 우수하였으며, 합성한 양이온 계면활성제가 섬유표면에 효과적으로 흡착되어 유연효과를 나타낼 수 있음을 확인하였다. In this study, a cationic surfactant BHMAS (N,N-bis-(3`-n-dodecyloxy-2`-hydroxypropyl)-N-methyl-2-hydroxyethylammonium methyl sulfate) having two lauryl and three hydroxyl groups was synthesized by the reaction of n-dodecyl glycidyl ether and 2-aminoethanol followed by the quarternization with dimethyl sulfate. The structure of the product was elucidated by 1 H-NMR and FT-IR. The CMC (critical micelle concentration) and surface tension of BHMAS at CMC condition were found to be 9.12 × 10 -4mol/L and 28.71mN/m respectively. Dynamic surface tension measurements using a maximum bubble pressure tensiometer indicated that a relatively long time was required to saturate the interface between air and aqueous surfactant solution. The interfacial tension measured between 1 wt% surfactant solution and n-decane reached an equilibrium value of 0.045mN/m in 5 min. The adsorption capacity of the synthesized surfactant was observed to be excellent, which suggests that the surfactant can be used as a softening agent during a laundry process.

상대습도 및 저장 온도가 분말녹차의 품질에 미치는 영향

이정민(Jung-Min Lee),임상욱(Sang-Wook Lim),조성환(Sung-Hwan Cho),최성길(Sung-Gil Choi),허호진(Ho-Jin Heo),이승철(Seung-Cheol Lee) 한국식품영양과학회 2009 한국식품영양과학회지 Vol.38 No.1

분말 녹차를 상대습도(23, 69, 81%)와 온도(-20, 4, 20℃)를 달리하여 3달간 저장한 후, 1.5 g에 100 mL을 첨가하여 추출물을 제조하여 총 페놀 함량, 총 플라바놀 함량, 아스코르브산 함량, 카테킨 함량의 변화를 조사하였다. 상대습도 23%, 4℃의 조건에 저장한 경우에서 총 페놀 함량, 총 플라바놀 함량, 아스코르브산 함량이 가장 높았는데 각각 287.1 ㎎/g, 44.9 ㎎/g, 36.9 ㎎/g의 값을 보였다. 이는 저장 초기의 각각의 측정값인 267.5 ㎎/g, 49.4 ㎎/g, 24.2 ㎎/g에 비해 총 페놀과 아스코르브산은 증가하였고, 총 플라바놀 함량은 감소하였다. 카테킨류의 경우에도 상대습도 23%, 4℃에 저장하였을 때 가장 높았는데 주된 카테킨인 EGC와 EGCG는 초기의 16.9와 27.3 ㎎/g에서 3달 후에는 각각 24.3과 36.5 ㎎/g으로 증가하였다. 또한 카페인도 같은 조건에서 초기의 20.7 ㎎/g에서 3달 후에는 30.7 ㎎/g으로 증가하였다. 그러나 상대습도가 높고 온도가 -20℃나 20℃에 저장한 경우에는 상대적으로 각 성분들이 감소하는 경향을 나타내었다. 이러한 결과는 분말 녹차의 상대습도와 저장 온도가 녹차의 품질 보존에 매우 중요하며, 낮은 습도에서 냉장 상태로 저장하는 것이 녹차의 품질 유지에 유리함을 의미한다. After storing green tea powder for three months at three different temperatures (-20, 4, and 20℃) with three different relative humidities (RHs) (23, 69, and 81%), the chemical quality was evaluated with green tea, which was prepared by soaking 1.5 g of the powder into 100 mL of distilled water at 70℃ for 5 min. Total phenolic contents, total flavanol contents, and ascorbic acid contents of green tea powder stored at 4℃ with 23% RH changed from 267.5, 49.4, and 24.2 ㎎/g to 287.1, 44.9, and 36.9 ㎎/g, respectively, compared to the powder before storage. EGC and EGCG, the main catechins of green tea, also changed from 16.9 and 27.3 ㎎/g to 24.3 and 36.5, g/g, respectively, after storage for 3 months at 4℃ with 23% RH. However, when the green tea powder was stored at -20 or 20oC with higher RH such as 69 and 81%, the chemical compounds were significantly decreased. The results indicate that temperature and RH are important during storage of green tea powder, and low RH and refrigerated condition (-4oC) are preferable to increase or preserve the chemical compounds of the tea.

C -11 및 F - 18 표지 콜린의 합성과 체내동태에 관한 연구

전권수,유국현,김상욱,임상무,홍성운,서용섭,양승대,안순혁,허민구 대한핵의학회 2001 핵의학 분자영상 Vol.35 No.3

Objectives: Recently, [methyl-(11)^C]-(β-Hydroxyethyl)trimethylammonium ([(11)^C]choline) has been discovered to be a very effective tracer in imaging various human tumors using positron emission tomography. Because of the short half-life of C-11, it is very difficult to use in a routine imaging procedure and needs a frequent synthesis of [(11)^]choline. This can be supplemented by the substitution of [(11)^Ccholine with [methyS-18]fluorocholine. Here, we would like to report cell uptake and biodistribution of [(11)^Ccholine and [(18)^F]fluorocholine as a basic study. Methods [(11)^C]Choline was prepared by the treatment of [(11)^C]CHzI with N,N-dimethylaminoethanol and [18F]fluorocholine was synthesized from reaction of CHzBr[18F]F with N,N-dimethylaminoethanol. The radiochemical purity was checked by high performance liquid chromatography (HPLC). The biodistribution of [(11)^C]choline and [(18)^F]fluorocholine was determined in balb/c mouse at 5 min, 20 min, 40 min and 80 min. The cell uptake wa measured using glioma (9L) and colon adeocarcinoma (SW620). Results: The radiochemical purity was more than 98% after purification. In the liver, uptake did not change over time the uptake was 20/ID/g for [C]choline and 13%ID/g for [(18)^F]fluorocholine. In the kidney, radioactivity decreased over tirne the uptake was 15%1D/g for [(11)^Ccholine and 20%ID/g for [(18)^F]fluorocholine, 80 min post-injection. The cell uptake of [(11)^Ccholine was 4.93% for glioma (9L) and 18.69F for colon adenocarcinoma (SW620). For [(18)^F]fluorocholine, 1.77% for glioma (9L) and 2.77% for colon adenocarcinoma (SW620). Conclusion: [(11)^CCholine and [(18)^F]fluorocholine showed a different cell uptake tendency, depending on cancer cell line. (Korean J Nucl Med 200135:185-191)

성인에서 기관내삽관을 위한 Pipecuronium 일회 정주 적정 용량

최영석,윤석민,임상호,이미경,박영철,류태간 대한마취과학회 1997 Korean Journal of Anesthesiology Vol.33 No.3

Background : Studies in animals suggest that pipecuronium dose not induce hemodynamic chan-ges related to histamine release or to an effect on the autonomic nervous system. Therefore the effects of bolus administration of large doses of pipecuronium, up to 0.20 mg/kg, on the intubation condition, onset and duration of neuromuscular blockade, heart rate and blood pressure were studied during fentanyl- nitrous oxide anesthesia. Method : Forty adults were randomly assigned to receive a bolus injection of either 0.05, 0.10, 0.15, 0.20 mg/kg of pipecuronium. Neuromuscular blockade was measured using mechanomyographic activity of the adductor pollicis muscle after supramaximal stimulation of the ulnar nerve. Four subgroups of 10 patients received pipecuronium doses of 0.05, 0.10, 0.15 and 0.20 mg/kg, respectively, as an intubating dose. Results : The times of onset and clinical duration(mean sem) after each dose were as follows: 0.05 mg/kg, 2.98 0.42 and 41.5 2.42 min; 0.10 mg/kg, 1.54 0.06 and 82.9 7.48 min; 0.15 mg/kg, 1.41 0.14 and 124.8 13.1 min; 0.20 mg/kg, 1.12 0.05 and 187.1 12.8 min. The intubation condition, time of onset and duration after doses of 0.05 mg/kg were significantly different from values after the higer doses. The duration was increased with dose-increments. No dose-related changes in heart rate or blood pressure were observed. Conclusion : The authors conclude that dose of 0.10 mg/kg and over has good intubation condition clinically and large bolus dose of pipecuronium can be safely used with a significantly prolonged duration of action without hemodynamic change. (Korean J Anesthesiol 1997; 33: 453∼457)

Five-minute synthesis of silver nanowires and their roll-to-roll processing for large-area organic light emitting diodes

Sim, Hwansu,Kim, Chanho,Bok, Shingyu,Kim, Min Ki,Oh, Hwisu,Lim, Guh-Hwan,Cho, Sung Min,Lim, Byungkwon The Royal Society of Chemistry 2018 Nanoscale Vol.10 No.25

<P>Silver (Ag) nanowires (NWs) are promising building blocks for flexible transparent electrodes, which are key components in fabricating soft electronic devices such as flexible organic light emitting diodes (OLEDs). Typically, Ag NWs have been synthesized using a polyol method, but it still remains a challenge to produce high-aspect-ratio Ag NWs <I>via</I> a simple and rapid process. In this work, we developed a modified polyol method and newly found that the addition of propylene glycol to ethylene glycol-based polyol synthesis facilitated the growth of Ag NWs, allowing the rapid production of long Ag NWs with high aspect ratios of about 2000 in a high yield (∼90%) within 5 min. Transparent electrodes fabricated with our Ag NWs exhibited performance comparable to that of an indium tin oxide-based electrode. With these Ag NWs, we successfully demonstrated the fabrication of a large-area flexible OLED with dimensions of 30 cm × 15 cm using a roll-to-roll process.</P>