신장기능영상용 방사성의약품 Bz - MAG3 ( Benzoylmercaptoacetylglycylglycylglycine ) 의 키트화 및 체내분포

고창순(Chang Soon Koh),이명철(Myung Chul Lee),정준기(June Key Chung),이동수(Dong Soo Lee),김영주(Young Ju Kim),정재민(Jae Min Jeong),장영수(Young Soo Chang),조정혁(Jung Hyuk Cho) 대한핵의학회 1996 핵의학 분자영상 Vol.30 No.3

N/A The MAG3 is a tubular excreting radiopharmaceutical for renal image. We synthe-sized benzoyl MAG3 (Bz-MAG3) and made a kit for labeling with Tc-99m. We checked the labeling effeciency of Tc-99m labeled MAG3 and biodistribution. Labeling efficiency was checked by TLC- SG (acetonitrile/H2O=2/1). After injecting of 1 mCi of Tc-99M-MAG3 to ICR-mice, Tmax(min), T1/2(min) were obtained in the renogram. Sequencial images (30sec, 2min, 5min, 10min, 15min, 20min) of TC-99m-MAG3 were compared with those of commercial Tc-99m-DTPA (Du Pont Merck Pharmaceutical Co.) kit. 1) The Rf value of synthesized Tc-99m-MAG3 was 0.78 and labeling efficiency was 97.5±1.9% (n=10). 2) The dynamic images of the Tc-99m-MAG3 were better than those of the Tc-99m-DTPA. 3) The Tmax(min.) and T1/2(min.) of Tc-99m-MAG3 (n=10) were 1.5±0.5 (left), 1.4±0.4(right), and 4.3±1.4 (left), 4.8±2.0 (right), respectivel. The Tmax(min.) and T1/2(min.) of Tc-99m-DTPA (n=7) were 2.7±1.6 (left), 2.7±1.6 right), and 3.8±1.7 (left), 4.5±2.7 (right), respectively. The quaility of image and labeling efficiency of the synthesized Bz-MAG3 kit were excellent, that it was supposed to be used in routine clinical work.

Long second toe: its nail and skin changes

( Geun-hwi Park ),( Woo-il Kim ),( Min-young Yang ),( Won-ku Lee ),( Tae-wook Kim ),( Sung-min Park ),( Hyun-joo Lee ),( Gun-wook Kim ),( Hoon-soo Kim ),( Hyun-chang Ko ),( Byung-soo Kim ),( Moon-bum 대한피부과학회 2018 대한피부과학회 학술발표대회집 Vol.70 No.2

Background: Nail can be affected by trauma, infection, and systematic disorders. In particular, the toe nails are exposed to the repeated and cumulative minor traumas, which usually result in thickened, splitted, and discolorated nails. Considering these, it can be inferred that the long second toe can be related to various nail and skin changes by repeated minor traumas such as friction in shoes, but the study or report on this topic hasn’t been done yet. Objectives: The purpose of this study was to introduce various nail and skin changes on long second toe. Methods: We analyzed the kinds of nail/skin changes of 50 patients with long second toe, enrolled at Pusan National University Hospitals (Busan and Yangsan) from 2013 to 2018. Results: There was no significant difference in the incidence of left and right toe and toenail, and 7 (14%) patients presented bilateral distribution. The most common nail change on long second toe was melanonychia (23, 46%), followed by subungual hematoma (15, 30%), onycholysis (2, 4%), subungual hyperkeratosis (2, 4%), onychomadesis (1, 2%), and retronychia (1, 2%). The most common skin change was corn (9, 18%), followed by paronychia (2, 4%). Twenty (20/50, 40%) patients also had other toe or toenail changes. Among them, the most common site was big toe/nail (13, 62%), and the most common change was subungual hematoma (8, 42%). Conclusion: Through this study, the dermatologists can recognize and diagnose the nail and skin changes of long second toe.

18–30세 사이에 발생하는 뇌경색의 특징, 다기관 레지스트리 연구

장윤경,송태진,김용재,허지회,이경열,김영은,장민욱,조수진,강석윤 이화여자대학교 의과학연구소 2017 EMJ (Ewha medical journal) Vol.40 No.3

Objectives: Although there have been several reports that described characteristics for young age stroke, information regarding very young age (18–30 years old) has been limited. We aimed to analyze demographic factors, stroke subtype, and 3-month outcome in acute ischemic stroke patient who have relatively very young age in multicenter stroke registry. Methods: We evaluated all 122 (7.1%) consecutive acute ischemic stroke (within 7 days after symptom onset) patients aged 18 to 30 from 17,144 patients who registered in multicenter prospective stroke registry, 1997 to 2012. Etiology was classified by Trial of Org 10172 in Acute Stroke Treatment criteria. Stroke severity was defined as National Institutes of Health Stroke Scale (NIHSS) and stroke outcome was defined by modified Rankin scale (mRS) at 3 months after index stroke. Results: The mean age of all included patients was 25.1±3.7 years and 76 patients (62.2%) were male. The median NIHSS at admission was 4. Considering stroke subtype, 37 patients (30.3%) had stroke of other determined etiology (SOD), 37 (30.3%) had undetermined negative evaluation (UN) and 31 (25.4%) had cardioembolism (CE) were frequently noted. After adjusting age, sex and variables which had P<0.1 in univariable analysis (NIHSS and stroke subtype), CE stroke subtype (odds ratio, 4.68; 95% confidence interval, 1.42–15.48; P=0.011) were significantly associated with poor functional outcome (mRS≥3). Conclusion: In very young age ischemic stroke patients, SOD and UN stroke subtype were most common and CE stroke subtype was independently associated with poor discharge outcome.

용성산인(龍城山人) 이창원(李昌遠)의 사상학설(四象學說)과 체질침(體質鍼)에 대한 고찰(考察)

안창범,윤현민,허재영,권혜연,Ahn, Chang-beohm,Youn, Byuon-Min,Hea, Jae-young,Kwon, Hae-Yon 대한침구의학회 2002 대한침구의학회지 Vol.19 No.1

Objective : This study was carried out to review Chang-Won Lee's theory of Sasangand acupuncture of constitution. Methods : We have investigated Chang-Won Lee's unknown literature "Medicine of sassang "(四象醫學). Results : Constitutional acupuncture is based on the diversity of human being and medically developed the response variation to disease and acupuncture. The diversity is due to the Organ's Congenital Formation Variation based on human nature and it is categorized as four from physiology, pathology, symptoms, to therapy. Chang-Won Lee's constitutional acupuncture discriminated constitution of comparison palpations of right and left both sides. He insisted that constitution only four type(Sasang), not exist man of To-Hyoung (土形人) in "young -chu"(靈樞) and his constitutional acupuncture all used Jung-kyuck (reinforcement acupuncture method) and Seong-kyuck(reducing acupuncture method) of Sa-am(舍岩)

Rat의 복강내에 투여한 5-fluorouracil-polyglycolic acid 제형이 장기에 미치는 영향에 관한 연구

강대영,송규상,최정목,노승무,정경수,오정연,김진향,양준묵,최선웅,이진호,조준식,민병무,김용백,김창식,박근성,김승영,김학용,인현빈 충남대학교 의과대학 지역사회의학연구소 1998 충남의대잡지 Vol.25 No.1

For more effective intraperitoneal chemotherapy, the authers made 5-fluorouracil-polyglycolic acid composite disks(FU-PGA disks) with 5-fluorouracil and polyglycolic acid, a biodegradable polymer. We inserted the FU-PGA disk into the peritoneal cavites of Sprague-Dawley male rats, the control and three experimental groups; one FU-PGA disk insert group(300mg/kg), two FU-PGA disk insert group(600mg/kg), and three FU-PGA disk insert group(900mg/kg). The control group received a similar number of PGA disk inserts. A pharmacokinetic study was performed to measure the 5-fluorouracil concentration in the peritoneal fluid, blood, and tissues(liver, kidney and heart) at 24 hours, 72hours and 168 hours after insertion of the FU-PGA disk. Light and electron microscopic studies were done. The results were as follows: 1) The number of white blood cells and platelets decreased after FU-PGA insertion. The degree was proportional to the duration and amounts inserted. The change in the number of red blood cells varied slightly. 2) Light microscopically, slight changes were noted at 168 hours in the 3 disk insert group (900mg/kg). Mild fatty change and hepatocyte degeneration around the central veins of the liver were noted, with vacuolar degeneration in the proximal convoluted tubules of the kidney. 3) Electron microscopically,the liver showed focal increases of lipid droplets in the hepatocytes, and irregular nuclear membrane with focal nucleolar segregation of the fibrillar and granular elements. Also the double membranous structure of the hepatocytes and Kupffer cells was widened with bleb formation. The kidney showed wide separation of the nuclear double membrane in the proximal convoluted tubular cells and mesangial cells, with vacuolation and myelin figure formation in the mitochondria of the proximal convoluted tubular cells, at 72 hours and 168 hours in the 2 to 3 FU-PGA insert groups. The heart showed focal loss of cristae,vacuolation and myelin figure formation in the mitochondria of the 2 to 3 FU-PGA insert groups. In conclusion, despite the large amont of FU-PGA inserted, the histopathological changes in the liver, kidney and heart were slight, and consonant with the very low amount of 5-fluorouracil concentrations detected in the liver, kidney and heart. The above results suggest that the FU-PGA composite can serve as a new device for releasing drugs in a controlled manner and easily targeted to intraperitoneal organs. This device can improve the efficacy of intraperitoneal chemotherapy for gastric cancer.

속박 (束縛) 과 침수 (浸水) 로 유도된 흰쥐의 스트레스성 급성 (急性) 위점막병변 (胃粘膜病變) 발생에 있어서 위산분비의 (胃酸分泌) 역할

민영일(Young Il Min),박충기(Choong Kee Park),장린(Rin Chang),김병호(Byung Ho Kim),장영운(Young Woon Chang),이정일(Jung Il Lee),박승준(Seung Joon Park),정주호(Joo Ho chung),정지창(Jee Chang Jung) 대한소화기학회 1989 대한소화기학회지 Vol.21 No.1

N/A The possible roles of gastric acid secretion in the pathogenesis of stress ulcers induced by restraint with water-immersion for 7 hours in pylorus-ligated rats were investigated. Control rats with pylorus-ligation only did not show any gastric mucosa} lesion, and their mean gastric acid output was 449.2 ± 36.1 umol/rat. In contrast, the stressed rats, group II, showed multiple, punctate and hemorrhagic erosions in gastric mucosa, and mean gastric acid output was decreased to the level of 253.7 ± 27.3 umol/rat. Subcutaneous administration of histamine(40 mg/kg every 2.5 h for a total three times) to stressed rats augmented the lesion with severe multiple, linear and hemorrhagic erosions and mean acid output increased significantly (328.1 ± 31.5 umol/, p<0.005) compared with group II. Pretreatment with rantidine(20 mg/kg) or prostaglandin E2 (30 ug/kg) before exposure to stress reduced gastric lesion formation slightly with no significance. In ranitidine pretreated rats, mean gastric acid output was decreased significantly (120.1 ± 15.3 umol/rat, p<0.005) compared with group II. However, in prostaglandin pretreated rats, mean gastric acid output showed no significant changes. Therefore, it is suggested that increased gastric acid secretion seems to be an aggravating or a permissive factor rather than a major factor in the pathogenesis of stress-induced gastric mucosal lesions.

고혈당증과 신적출 후 신증의 실험적 흰쥐 모형에서 신사구체의 형태계측학적 연구 - 사구체 경화증의 발달 과정과 기전에 관한 연구 -

심영웅 ( Young Woong Shim ),설미영 ( Mee Young Sol ),이경민 ( Kyeong Min Lee ),최경운 ( Kyung Un Choi ),김지연 ( Jee Yeon Kim ),이진숙 ( Jin Sook Lee ),박도윤 ( Do Youn Park ),이창훈 ( Chang Hoon Lee ),서강석 ( Kang Suek Suh ) 대한신장학회 2002 Kidney Research and Clinical Practice Vol.21 No.6

목적 : 당뇨병의 가장 흔한 합병증의 당뇨병성 신중에서 현저한 조직 변화인 사구체의 섬유화와 이와 유사한 조직 소견을 보이는 다른 질병들과의 관련성 및 섬유화 기전의 기전의 일단을 밝히기 위하여 연구를 시행하였다. 방 법 : 당뇨병성 신증과 신 조직 일부 소실 후 발생하는 신 적출 후 신증, 생리적 노령화로 인한 사구체 섬유화 등에서 섬유화가 일어나는 시기와 부위, 섬유화의 정도와 시간 경과에 따른 변화 등을 조사하기 위하여 실험 동물 모형을 이용하여 형태계측학적 연구를 하였다. 수컷 Sprague-Dowley (이하 S-D) 흰쥐에 streptozotocin을 꼬리 정맥으로 투여하여 당뇨병성 신증 모델을 만들고, S-D 백서의 우측 신장을 절제하여 과여과 모형을 만들었다. 시술 후 일정 기간이 지난 후 시기별로 희생시켜 Sirius red 염색 표본을 만들어 시구체 단면적과 실질의 섬유화 정도를 측정하고, 전자현미경으로 얻은 사구체 소견에서 메산지움 기질의 면적, 사구체 기저막의 두께, 근위우곡세뇨관 기저막의 두께 등을 조사하였다. 이들에서 질병 시기에 따른 변화, 두 실험군 사이의 차이, 정상 대조군 및 생리적 노화 대조군과의 차이 등을 분석하였다. 결 과 : 당뇨병성 신증 모델에서 사구체 단면적은 실험8주 이후 24주까지 전 예에서 정상 대조군에 비해 크기가 의의있게 증가하였고 신 실질과 사구체 내의 섬유화는 실험 2주 째부터 대조군에 비해 의의있는 교원질 양의 증가가 있었다. 사구체 기저막은 streptozotocin 투여 1주에 희생시킨 군에서도 의의있는 두께의 증가가 있었고, 세뇨관 기저막도 3주에 측정한 군에서부터 현저한 두께의 증가가 있었다. 우측신 절제를 시행한 모형에서 사구체 평면적은 실험 7주군에서 커진 소견이 나타났고 16주 이후의 군대에서는 현저한 크기의 증가 소견이 있었다. 신실질과 사구체의 교원질 염색 소견에서 2주 이후 전 기간에 걸쳐 교원질 양의 증가가 있었고, 사구체 기저막과 세뇨관 기저막 두께는 술 후 2주에 희생시킨 군부터 두께가 의의있게 증가하였다. 생리적 노화과정을 거친 군에서도 사구체의 섬유화가 나타났는데 당뇨병 모형과 신적출 모형에 비해 그 정도는 덜하였다. 당뇨병 모형과 신적출 모형 사이의 사구체 조직 변화는 실험 기간이 긴 군들에서 사구체 평면적의 크기, 교원질 양의 증가, GBM과 TBM의 두께 등이 두 군 모두 현저한 증가를 보였고 신적출 모형에서 실험 최종 기간이 같지 않아 실험 수치의 비교가 의미가 없을 것으로 생각된다. 결 론 : 이상의 성적에 의거하면 신사구체와 간질의 섬유화, GBM과 TBM의 두께 증가는 당뇨병성 신증만의 특징적인 조직 변화는 아니고 신 실질 일부 소실이 일어나는 사구체 질환에서 공통적으로 일어나는 소견이다. 그러므로 본 연구의 대상이 된 당뇨병성 신중, 신적출 후 신증, 그리고 생리적 노화 과정 등에서 공통적으로 나타나는 사구체 모세관의 혈역동학적 변화가 사구체의 섬유화에 병인기전을 밝히는데 중요한 요소가 될 것으로 사료된다. Objective :Diabetic nephropathy and ablation nephropathy are characterized by sclerotic processes in the glomeruli. To elucidate the site, degree and time-honored changes of glomerular sclerosis, morphometric analysis was performed using the experimental animals models. Methods : The animals used were male Sprague-Dowley rats and separated into 4 groups as young mormal control, old control, streptozotocin-injected group, and right nephrectornized group. Chronologically kidney specimens were obtained after each treatment and processed to evaluated histologic changes. To evaluated the glomerular area, interstitial fibrosis and glomerular tuft fibrosis, the kidney specimens were fixed in Buin`s solution, paraffin-embedded and 2 ㎛ sections were Sirius red stained. To study the mesangial area, mesangial matrix area, glomerular basement membrane, and tubular basement membrane, the specimens were fixed in 2,5% glutaraldehyde, epon-embedded, double-stained and examined under the transmission electron microscope. All the specimens were analyzed morphometrically using the Image Pro Plus software. The obtained morphometric data were statistically analyzed to evaluate the differences of fibrotic processes and degree between experimental groups. Results : Diabetic group revealed statistically significant increase of glomerular area from 8th week after streptozotocin injection to 24th week of experimental date. The parenchymal fibrosis and glomerular tuft fibrosis was prominent from the 2nd week of injection and steadily increased until the end of experimental date. The thickness of glomerular basement membrane was significantly increased even at the first week of injection and the tubular basement membrane also increased in thickness at the 3rd week of experiment. Ablation nephropathy model made by right nephrectomy showed increased glomerular area at the 7th week of ablation and the degree were intensified after 16th week of experimental date. The amount of stainable collagen in the renal parenchyme and glomerular tuft increased in the second week kidney sample and steadily increased thereafter until the end of experimental date. The increase of thickness of GBM and TBM also started to appear at the second week of operation. The old control also revealed fibrosis but the degree was less than the diabetic and ablation groups. Both diabetic and ablation nephropathy groups exhibited extensive increase of glomerular area, stainable collagen, thickness of GBM and TBM at the end of experimental date and the ablation group revealed more extensive evidences of fibrosis without statistical significance. Comparison between the experimental groups were meaningless because the duration of the experimental manipulation was not the same. Conclusion: Glomerular and renal interstitial sclerosis and thickening of GBM and TBM are not the specific lesions of the diabetic glomerulopathy and are the common histologic changes occur in the kidney of partial parenchymal loss of any etiology. And it is suggested by this study that the common hemodynamic change involving the diabetic nephropathy, ablation nephropathy and physiologic aging is one of the important pathogenetic factors of glomerular sclerosis.

정신분열병에 대한 리스페리돈의 효과 및 안정성

이민수,김용구,김영훈,연병길,오병훈,윤도준,윤진상,이철,정희연,강병조,김광수,김동언,김명정,김상훈,김희철,나철,노승호,민경준,박기창,박두병,백기청,백인호,손봉기,손진욱,양병환,양창국,우행원,이정호,이종범,이홍식,임기영,전태연,정영조,정영철,정인과,정인원,지익성,채정호,한상익,한선호,한진희,서광윤 大韓神經精神醫學會 1998 신경정신의학 Vol.37 No.1

연구목적 : 본 시험의 목적은 임상시험 시작전에 연구자들을 대상으로 PANSS Workshop을 통하여 PANSS, ESRS에 대한 국내에서의 표준화 작업을 구축하고 새로운 정신병 치료제인 리스페리돈의 효과와 안정성을 재확인하여 리스페리돈 사용에 대한 적정화를 이루는데 있다. 연구방법 : 1996년 4월부터 1996년 9월까지 국내 39개 대학병원 정신과에 입원중인 혹은 증상이 악화되어 입원하는 정신분열병 환자 377명을 대상으로 다시설 개방 연구를 시행하였다. 1주일간의 약물 배설기간을 가진후, 리스페리돈을 8주간 투여하였고, 기준점, 1주, 2주, 4주, 그리고 8주후에 평가되었다. 용량은 제1일에는 리스페리돈 1mg씩 1일 2회, 제2일에는 2mg씩 1일 2회, 제3∼7일에는 3mg씩 1일 2회 투여하였다. 이후 환자의 임상상태에 따라 임의로 증량할 수 있으며, 최대 일일 16mg을 초과하지 않도록 하였다. 추체외로 증상을 조절하기 위한 투약을 허용하였다. 임상증상 및 부작용의 평가는 PANSS(Positive and Negative Syndrome Scale), CGI(Clinical Global Impression) 그리고 ESRS(Extrapyramidal Symptom Rating Scale)을 사용하였다. 연구결과 : 377명중 343명(91%)이 8주간의 연구를 완결하였다. 치료 종결시점인 8주후 PANSS 총점수가 20% 이상 호전된 경우를 약물 반응군으로 정의할때, 약물반응군은 81.3%였다. 리스페리돈에 반응하는 예측인자로는 발병연령, 이전의 입원 횟수, 유병기간이 관련 있었다. 리스페리돈은 1주후부터 PANSS양성, 음성, 및 일반정신병리 점수상에 유의한 호전을 보여 효과가 빨랐다. CGI의 경우도 기준점에 비해 1주후부터 유의한 감소를 나타내었다. ESRS의 경우, 파킨슨 평가점수는 기준점과 비교해 투여 1주, 2주, 4주후 유의하게 증가되었다가 8주후 기준점과 차이가 없었다. Dystonia 평가점수는 1주후만 유의한 증가를 보였으며, dyskinesia 평가점수는 유의한 차이가 없었다. 혈압, 맥박수의 생명징후 및 일반 혈액학 검사, 생화학적 검사, 심전도 검사에서 유의한 변화는 없었다. 결 론 : 이상의 다시설 개방 임상 연구를 통해 리스페리돈은 정신분열병 환자에서 양성증상뿐만 아니라 음성증상 및 전반적인 증상에도 효과적인 것으로 사료된다. 보다 명확한 평가를 위해서는 다른 항정신병약물과의 이중맹검 연구가 필요할 것으로 생각되며, 또한 장기적 치료에 대한 평가도 함께 이루어져야 하겠다. Objective : The purpose of this study was to investigate the efficacy and safety of risperidone in the treatment of Korean schizophrenic patients. Method : This multicenter open study included 377 schizophrenic patients drawn from 39 university hospitals. After a wash-out period of 1 week, the schizophrenic patients were treated with risperidone for 8 weeks and evaluated at 5 points ; at baseline, and 1, 2, 4 and 8 weeks of treatment. The dose was increased from 2mg/day(1mg twice daily) to 6mg/day(3mg twice daily) during the first week and adjusted to a maximum of 16mg/day over the next 7 weeks according to the patient's clinical response. Medication to control extrapyramidal symptoms was permitted. The psychiatric and neurological status of the patients was assessed by PANSS, CGI, and ESRS scales. Results : 343(91%) of 377 patients completed the 8-week trial period. Clinical improvement, as defined by a 20% or more reduction in total PANSS score at end point, was shown by 81.3% of patients. The predictors of response to risperidone were associated older age, shorter duration of illness, fewer previous hospitalization. Risperidone had rapid onset of action ; a significant decrease of the total PANSS and three PANSS factor(positive, negative, general), and CGI was already noticed at the end of first week. For the ESRS, parkinsonism rating scores were significantly increased until week 4 comparing with baseline. Dystonia rating scores were significantly increased until week 1, and dyskinesia rating scores were not significantly changed during the study. Laboratory parameters including vital sign, EKG, hematological, and biochemical values showed no significant changes during the trial. Conclusions : This study suggests that risperidone is generally safe and effective against both the positive and negative symptoms in our group of patients.

Soymilk를 이용한 요구르트 제조 및 저장기간 동안의 품질변화에 관한 연구

신상민 ( Sang Min Shin ),송광영 ( Kwang Young Song ),서건호 ( Kun Ho Seo ),윤여창 ( Yoh Chang Yoon ) 한국유가공기술과학회 2012 한국유가공기술과학회지 Vol.30 No.2

This study was performed for analyzing the general composition and the change in the quality of soymilk-derived yogurts manufactured by adding skim milk and whey powder to soymilk heat-treated at 95℃/5 min and 120℃/10 min, respectively. 1. During the storage of soymilk yogurt, the concentrations of total solids, protein, fat, and lactose slightly decreased, whereas viscosity, content of ash and NPN, and the number of lactic acid bacteria remained unchanged. 2. The pH and titratable acidity changed rapidly in all soymilk yogurts after 3 h of incubation. 3. We found 7.8×108 lactic acid bacteria in the control sample, 4.7×108 and 5.02×108 in soymilk yogurt with skim milk, respectively, and 5.9×108 and 5.5×108, respectively in soymilk yogurt with whey powder according to degree of heat treatment with 95℃/5 min and 120℃/10 min. 4. The viscosity of yogurt samples became lower as the heat treatment increased in temperature and in the length of time. 5. The value of sensory evaluation was relatively high in soymilk yogurt with the added skim milk, which was heat-treated 95℃/5 min; however, the value was significantly lower than that of the control sample. 6. Lactose, glucose, and galactose were detected in all samples because lactose is degraded into glucose and galactose within 3 h of inoculation.

Using Real-Time Electron Microscopy To Explore the Effects of Transition-Metal Composition on the Local Thermal Stability in Charged Li_<i>x</i>Ni_<i>y</i>Mn_<i>z</i>Co_{1–<i>y</i>–<i>z</i>}O<sub>2</sub

Hwang, Sooyeon,Kim, Seung Min,Bak, Seong-Min,Kim, Se Young,Cho, Byung-Won,Chung, Kyung Yoon,Lee, Jeong Yong,Stach, Eric A.,Chang, Wonyoung American Chemical Society 2015 Chemistry of materials Vol.27 No.11

<P>In this work, we use in situ transmission electron microscopy (TEM) to investigate the thermal decomposition that occurs at the surface of charged LixNiyMnzCo1-y-zO2 (NMC) cathode materials of different composition (with y, z = 0.8, 0.1, and 0.6, 0.2, and 0.4,and 0.3), after they have been charged to their practical upper limit voltage (4.3 V). By heating these materials inside the TEM, we are able to directly characterize near surface changes in both their electronic structure (using electron energy loss spectroscopy) and crystal structure and morphology (using electron diffraction and bright-field imaging). The most Ni-rich material (y, z = 0.8, 0.1) is found to be thermally unstable at significantly lower temperatures than the other compositionsthis is manifested by changes in both the electronic structure and the onset of phase transitions at temperatures as low as 100 degrees C. Electron energy loss spectroscopy indicates that (i) the thermally induced reduction of Ni ions drives these changes, and (ii) this is exacerbated by the presence of an additional redox reaction that occurs at 4.2 V in the y, z = 0.8, 0.1 material. Exploration of individual particles shows that there are substantial variations in the onset temperatures and overall extent of these changes. Of the compositions studied, the composition of y, z = 0.6, 0.2 has the optimal combination of high energy density and reasonable thermal stability. The observations herein demonstrate that real-time electron microscopy provide direct insight into the changes that occur in cathode materials with temperature, allowing optimization of different alloy concentrations to maximize overall performance.</P>