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Kang SH, Choi Y, Chung SJ, Moon SJ, Kim CK, Kim JH, Oh K, Yoon JS, Seo SW, Cho GJ, Koh SB. Fasting glucose variability and risk of dementia in Parkinson's disease: a 9-year longitudinal follow-up study of a nationwide cohort. Front Aging Neurosci 2024; 15:1292524. [PMID: 38235038 PMCID: PMC10791804 DOI: 10.3389/fnagi.2023.1292524] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2023] [Accepted: 11/21/2023] [Indexed: 01/19/2024] Open
Abstract
Background Diabetes is associated with an increased risk of Parkinson's disease dementia (PDD); however, it is unknown whether this association is dependent on continuous hyperglycemia, hypoglycemic events, or glycemic variability. We aimed to investigate the relationship between visit-to-visit fasting glucose variability and PDD development in patients with Parkinson's disease (PD). Methods Using data from the Korean National Health Insurance Service, we examined 9,264 patients aged ≥40 years with de novo Parkinson's disease (PD) who underwent ≥3 health examinations and were followed up until December 2019. Glucose variability was measured using the coefficient of variation, variability independent of the mean, and average real variability. Fine and Gray competing regression analysis was performed to determine the effect of glucose variability on incident PDD. Results During the 9.5-year follow-up period, 1,757 of 9,264 (19.0%) patients developed PDD. Patients with a higher visit-to-visit glucose variability had a higher risk of future PDD. In the multivariable adjusted model, patients with PD in the highest quartile (subdistribution hazard ratio [SHR] = 1.50, 95% CI 1.19 to 1.88), quartile 3 (SHR = 1.29, 95% CI 1.02 to 1.62), and quartile 2 (SHR = 1.30, 95% CI 1.04 to 1.63) were independently associated with a higher risk of PDD than those in the lowest quartile. Conclusion We highlighted the effect of long-term glucose variability on the development of PDD in patients with PD. Furthermore, our findings suggest that preventive measures for constant glucose control may be necessary to prevent PDD.
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Affiliation(s)
- Sung Hoon Kang
- Department of Neurology, Korea University Guro Hospital, Korea University College of Medicine, Seoul, Republic of Korea
| | - Yunjin Choi
- Biomedical Research Institute, Korea University Guro Hospital, Korea University College of Medicine, Seoul, Republic of Korea
| | - Su Jin Chung
- Department of Neurology, Myongji Hospital, Hanyang University College of Medicine, Goyang, Republic of Korea
| | - Seok-Joo Moon
- Smart Healthcare Center, Korea University Guro Hospital, Korea University College of Medicine, Seoul, Republic of Korea
| | - Chi Kyung Kim
- Department of Neurology, Korea University Guro Hospital, Korea University College of Medicine, Seoul, Republic of Korea
| | - Ji Hyun Kim
- Department of Neurology, Korea University Guro Hospital, Korea University College of Medicine, Seoul, Republic of Korea
| | - Kyungmi Oh
- Department of Neurology, Korea University Guro Hospital, Korea University College of Medicine, Seoul, Republic of Korea
| | - Joon Shik Yoon
- Department of Physical Medicine and Rehabilitation, Korea University Guro Hospital, Seoul, Republic of Korea
| | - Sang Won Seo
- Department of Neurology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea
- Alzheimer’s Disease Convergence Research Center, Samsung Medical Center, Seoul, Republic of Korea
| | - Geum Joon Cho
- Department of Obstetrics and Gynecology, Korea University Guro Hospital, Korea University College of Medicine, Seoul, Republic of Korea
| | - Seong-Beom Koh
- Department of Neurology, Korea University Guro Hospital, Korea University College of Medicine, Seoul, Republic of Korea
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Park JG, Han SB, Park JH, Moon SJ, Jang WY. A Decline in Overutilization of Transfusion after Total Knee Arthroplasty Using Pharmacological Agents for Patient Blood Management in South Korea: An Analysis Based on the Korean National Health Insurance Claims Database from 2008 to 2019. Clin Orthop Surg 2023; 15:942-952. [PMID: 38045586 PMCID: PMC10689217 DOI: 10.4055/cios22312] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Revised: 12/23/2022] [Accepted: 01/05/2023] [Indexed: 12/05/2023] Open
Abstract
Background This study aimed to evaluate the annual trends of transfusion rates and utilization of blood management agents in total knee arthroplasty (TKA) based on the operation type and to analyze the risk factors of transfusion after TKA. Methods Using the Korean National Insurance claims database of 797,106 primary and revision TKAs between January 2008 and October 2019, data on the patients' characteristics, comorbidities, utilization of transfusion, and blood management agents were collected. The patients were categorized into three groups based on the operation type: primary, revision, and simultaneous bilateral TKA. The transfusion rate and utilization of blood management agents (intraoperative tranexamic acid [TXA] and preoperative iron supplements) were compared, and the risk factors for transfusion were evaluated. Results After excluding the inaccurate data, 730,554 arthroplasties (636,292 primary, 10,540 revision, and 41,861 simultaneous bilateral TKAs) were identified. The transfusion rates of primary, revision, and simultaneous bilateral TKAs in 2019 were 64.0%, 67.7%, and 68.9%, respectively, which were significantly decreased compared with 83.2%, 88.0%, and 92.5% in 2008, respectively (p < 0.001). Conversely, the utilization of intraoperative TXA and preoperative iron supplements was significantly increased from 4.6% and 13.8%, respectively, in 2008 to 52.4% and 27.0%, respectively, in 2019 (p < 0.001). The utilization of intraoperative TXA and preoperative iron supplements significantly lowered the risk of transfusion after TKA (odds ratio [OR], 0.20; p < 0.001 and OR, 0.71; p < 0.001). Conclusions The transfusion rate after TKA decreased gradually from 83.5% to 64.5% between 2008 and 2019 in South Korea corresponding with the increased utilization of blood management agents. Therefore, consistent attention to patient blood management should be emphasized to reduce the transfusion rate after TKA.
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Affiliation(s)
- Jun-Gu Park
- Department of Orthopedic Surgery, Korea University Anam Hospital, Korea University College of Medicine, Seoul, Korea
| | - Seung-Beom Han
- Department of Orthopedic Surgery, Korea University Anam Hospital, Korea University College of Medicine, Seoul, Korea
| | - Jong-Hoon Park
- Department of Orthopedic Surgery, Korea University Anam Hospital, Korea University College of Medicine, Seoul, Korea
| | - Seok-Joo Moon
- Department of Biostatistics, Korea University College of Medicine, Seoul, Korea
| | - Woo-Young Jang
- Department of Orthopedic Surgery, Korea University Anam Hospital, Korea University College of Medicine, Seoul, Korea
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Kang EJ, Moon SJ, Lee K, Park IH, Kim JS, Choi YJ. Associations between missing teeth and the risk of cancer in Korea: a nationwide cohort study. BMC Oral Health 2023; 23:418. [PMID: 37353779 PMCID: PMC10288806 DOI: 10.1186/s12903-023-02997-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Accepted: 04/28/2023] [Indexed: 06/25/2023] Open
Abstract
BACKGROUND Poor dental health is correlated with an increased risk of cancer. Using a nationwide population cohort database, we investigated which cancer is highly associated with poor dental health and which dental indicator mostly influences cancer risk. METHODS This study was conducted using the National Health Checkups (NHC) and National Health Insurance System (NHIS) database in Korea. NHC in Korea includes dental examinations. We retrieved subjects who underwent NHC between 2002 and 2003 and their medical information in NHIS database was followed until December 31,2015. RESULTS Data for 200,170 who participated in the NHC between 2002 and 2003 were analysed. During the maximum follow-up period of 13 years, 15,506 (7.75%) subjects were diagnosed with cancer. The median time to cancer diagnosis after the dental examination was 87 months (range, 51-119 months). The proportion of people with missing teeth was higher in the cancer-diagnosed group than in the non-diagnosed group (26.27% vs. 22.59%, p < 0.001). Among several dental health factors, missing teeth were significantly associated with higher cancer risk. Subjects with missing teeth showed a 12% increased cancer risk compared to those without missing teeth (odds ratio [OR] 1.12, 95% confidence interval [CI], 1.08-1.16). The risk was significantly higher, especially in lung, head and neck, pancreatic, liver, biliary, and esophageal cancers (OR 1.27 [95% CI, 1.14-1.41], 1.32 [95% CI, 1.13-1.55], 1.27 [95% CI, 1.02-1.58], 1.24 [95% CI, 1.1-1.4], 1.28 [95% CI, 1.03-1.6], 1.4 [95% CI, 1.04-1.88], respectively). CONCLUSIONS Missing teeth were the most important dental indicator associated with cancer risk. Korean adults with missing teeth should be cautious about the risk of several cancers, particularly head and neck, lung, gastrointestinal, hepatobiliary, and pancreatic cancer.
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Affiliation(s)
- Eun Joo Kang
- Department of Internal Medicine, Korea University Guro Hospital, Korea University College of Medicine, 148, Gurodong-Ro, Guro-Gu, Seoul, 08308, Republic of Korea.
| | - Seok-Joo Moon
- Smart Healthcare Center, Korea University Guro Hospital, 148, Gurodong-Ro, Guro-Gu, Seoul, 08308, Republic of Korea
| | - Kyoungmin Lee
- Department of Internal Medicine, Korea University Guro Hospital, Korea University College of Medicine, 148, Gurodong-Ro, Guro-Gu, Seoul, 08308, Republic of Korea
| | - In Hae Park
- Department of Internal Medicine, Korea University Guro Hospital, Korea University College of Medicine, 148, Gurodong-Ro, Guro-Gu, Seoul, 08308, Republic of Korea
| | - Jung Sun Kim
- Department of Internal Medicine, Korea University Ansan Hospital, Korea University College of Medicine, 123, Jeokgeum-Ro, Danwon-Gu, Ansan, Gyeonggi-Do, 15355, Republic of Korea
| | - Yoon Ji Choi
- Department of Internal Medicine, Korea University Anam Hospital, Korea University College of Medicine, 73 Goryeodae-Ro Seongbuk-Gu, Seoul, 02841, Republic of Korea
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Kang SH, Moon SJ, Kang M, Chung SJ, Cho GJ, Koh SB. Incidence of Parkinson's disease and modifiable risk factors in Korean population: A longitudinal follow-up study of a nationwide cohort. Front Aging Neurosci 2023; 15:1094778. [PMID: 36865411 PMCID: PMC9971569 DOI: 10.3389/fnagi.2023.1094778] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2022] [Accepted: 01/27/2023] [Indexed: 02/16/2023] Open
Abstract
Introduction We aimed to investigate the incidence of Parkinson's disease (PD) by age and year for each sex as well as the modifiable risk factors for PD. Using data from the Korean National Health Insurance Service, 938,635 PD and dementia-free participants aged ≥40 years who underwent general health examinations were followed to December 2019. Methods We analyzed the PD incidence rates according to age, year and sex. To investigate the modifiable risk factors for PD, we used the Cox regression model. Additionally, we calculated the population-attributable fraction to measure the impact of the risk factors on PD. Results During follow-up, 9,924 of the 938,635 (1.1%) participants developed PD. The incidence of PD increased continuously from 2007 to 2018, reaching 1.34 per 1,000 person-years in 2018. The incidence of PD also increases with age, up to 80 y. Presence of hypertension (SHR = 1.09, 95% CI 1.05 to 1.14), diabetes (SHR = 1.24, 95% CI 1.17 to 1.31), dyslipidemia (SHR = 1.12, 95% CI 1.07 to 1.18), ischemic stroke (SHR = 1.26, 95% CI 1.17 to 1.36), hemorrhagic stroke (SHR = 1.26, 95% CI 1.08 to 1.47), ischemic heart disease (SHR = 1.09, 95% CI 1.02 to 1.17), depression (SHR = 1.61, 95% CI 1.53 to 1.69), osteoporosis (SHR = 1.24, 95% CI 1.18 to 1.30), and obesity (SHR = 1.06, 95% CI 1.01 to 1.10) were independently associated with a higher risk for PD. Discussion Our results highlight the effect of modifiable risk factors for PD in the Korean population, which will help establish health care policies to prevent the development of PD.
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Affiliation(s)
- Sung Hoon Kang
- Department of Neurology, Korea University Guro Hospital, Korea University College of Medicine, Seoul, Republic of Korea
| | - Seok-Joo Moon
- Smart Healthcare Center, Korea University Guro Hospital, Korea University College of Medicine, Seoul, Republic of Korea
| | - Minwoong Kang
- Department of Biomedical Research Center, Korea University Guro Hospital, Korea University College of Medicine, Seoul, Republic of Korea
| | - Su Jin Chung
- Department of Neurology, Myongji Hospital, Hanyang University College of Medicine, Goyang, Republic of Korea
| | - Geum Joon Cho
- Department of Obstetrics and Gynecology, Korea University Guro Hospital, Korea University College of Medicine, Seoul, Republic of Korea
| | - Seong-Beom Koh
- Department of Neurology, Korea University Guro Hospital, Korea University College of Medicine, Seoul, Republic of Korea,*Correspondence: Seong-Beom Koh,
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Kim DH, Moon SJ, Lee J, Cha JK, Kim MH, Park JS, Ban B, Kang J, Kim BJ, Kim WS, Yoon CH, Lee H, Kim S, Kang EK, Her AY, Yoon CW, Rha JH, Woo SI, Lee WK, Jung HY, Lee JH, Park HS, Hwang YH, Kim K, Kim RB, Choi NC, Hwang J, Park HW, Park KS, Yi S, Cho JY, Kim NH, Choi KH, Kim J, Han JY, Choi JC, Kim SY, Choi JH, Kim J, Sohn MK, Choi SW, Shin DI, Lee SY, Bae JW, Lee KS, Bae HJ. Comparison of Factors Associated With Direct Versus Transferred-in Admission to Government-Designated Regional Centers Between Acute Ischemic Stroke and Myocardial Infarction in Korea. J Korean Med Sci 2022; 37:e305. [PMID: 36325609 PMCID: PMC9623032 DOI: 10.3346/jkms.2022.37.e305] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Accepted: 08/29/2022] [Indexed: 11/05/2022] Open
Abstract
BACKGROUND There has been no comparison of the determinants of admission route between acute ischemic stroke (AIS) and acute myocardial infarction (AMI). We examined whether factors associated with direct versus transferred-in admission to regional cardiocerebrovascular centers (RCVCs) differed between AIS and AMI. METHODS Using a nationwide RCVC registry, we identified consecutive patients presenting with AMI and AIS between July 2016 and December 2018. We explored factors associated with direct admission to RCVCs in patients with AIS and AMI and examined whether those associations differed between AIS and AMI, including interaction terms between each factor and disease type in multivariable models. To explore the influence of emergency medical service (EMS) paramedics on hospital selection, stratified analyses according to use of EMS were also performed. RESULTS Among the 17,897 and 8,927 AIS and AMI patients, 66.6% and 48.2% were directly admitted to RCVCs, respectively. Multivariable analysis showed that previous coronary heart disease, prehospital awareness, higher education level, and EMS use increased the odds of direct admission to RCVCs, but the odds ratio (OR) was different between AIS and AMI (for the first 3 factors, AMI > AIS; for EMS use, AMI < AIS). EMS use was the single most important factor for both AIS and AMI (OR, 4.72 vs. 3.90). Hypertension and hyperlipidemia increased, while living alone decreased the odds of direct admission only in AMI; additionally, age (65-74 years), previous stroke, and presentation during non-working hours increased the odds only in AIS. EMS use weakened the associations between direct admission and most factors in both AIS and AMI. CONCLUSIONS Various patient factors were differentially associated with direct admission to RCVCs between AIS and AMI. Public education for symptom awareness and use of EMS is essential in optimizing the transportation and hospitalization of patients with AMI and AIS.
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Affiliation(s)
- Dae-Hyun Kim
- Busan Regional Cardiocerebrovascular Disease Center, Dong-A University Hospital, Busan, Korea
| | - Seok-Joo Moon
- Department of Biostatistics, Korea University College of Medicine, Seoul, Korea
| | - Juneyoung Lee
- Department of Biostatistics, Korea University College of Medicine, Seoul, Korea
| | - Jae-Kwan Cha
- Busan Regional Cardiocerebrovascular Disease Center, Dong-A University Hospital, Busan, Korea
| | - Moo Hyun Kim
- Busan Regional Cardiocerebrovascular Disease Center, Dong-A University Hospital, Busan, Korea
| | - Jong-Sung Park
- Busan Regional Cardiocerebrovascular Disease Center, Dong-A University Hospital, Busan, Korea
| | - Byeolnim Ban
- Gyeonggi Regional Cardiocerebrovascular Disease Center, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, Korea
| | - Jihoon Kang
- Gyeonggi Regional Cardiocerebrovascular Disease Center, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, Korea
| | - Beom Joon Kim
- Gyeonggi Regional Cardiocerebrovascular Disease Center, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, Korea
| | - Won-Seok Kim
- Gyeonggi Regional Cardiocerebrovascular Disease Center, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, Korea
| | - Chang-Hwan Yoon
- Gyeonggi Regional Cardiocerebrovascular Disease Center, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, Korea
| | - Heeyoung Lee
- Gyeonggi Regional Cardiocerebrovascular Disease Center, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, Korea
| | - Seongheon Kim
- Gangwon Regional Cardiocerebrovascular Disease Center, Kangwon National University Hospital, Kangwon National University School of Medicine, Chuncheon, Korea
| | - Eun Kyoung Kang
- Gangwon Regional Cardiocerebrovascular Disease Center, Kangwon National University Hospital, Kangwon National University School of Medicine, Chuncheon, Korea
| | - Ae-Young Her
- Gangwon Regional Cardiocerebrovascular Disease Center, Kangwon National University Hospital, Kangwon National University School of Medicine, Chuncheon, Korea
| | - Cindy W Yoon
- Incheon Regional Cardiocerebrovascular Disease Center, Inha University College of Medicine, Incheon, Korea
| | - Joung-Ho Rha
- Incheon Regional Cardiocerebrovascular Disease Center, Inha University College of Medicine, Incheon, Korea
| | - Seong-Ill Woo
- Incheon Regional Cardiocerebrovascular Disease Center, Inha University College of Medicine, Incheon, Korea
| | - Won Kyung Lee
- Incheon Regional Cardiocerebrovascular Disease Center, Inha University College of Medicine, Incheon, Korea
| | - Han-Young Jung
- Incheon Regional Cardiocerebrovascular Disease Center, Inha University College of Medicine, Incheon, Korea
| | - Jang Hoon Lee
- Daegu-Gyeongbuk Regional Cardiocerebrovascular Disease Center, Kyungpook National University Hospital, Daegu, Korea
| | - Hun Sik Park
- Daegu-Gyeongbuk Regional Cardiocerebrovascular Disease Center, Kyungpook National University Hospital, Daegu, Korea
| | - Yang-Ha Hwang
- Daegu-Gyeongbuk Regional Cardiocerebrovascular Disease Center, Kyungpook National University Hospital, Daegu, Korea
| | - Keonyeop Kim
- Daegu-Gyeongbuk Regional Cardiocerebrovascular Disease Center, Kyungpook National University Hospital, Daegu, Korea
| | - Rock Bum Kim
- Gyeongnam Regional Cardiocerebrovascular Disease Center, Gyeongsang National University Hospital, Gyeongsang National University School of Medicine, Jinju, Korea
| | - Nack-Cheon Choi
- Gyeongnam Regional Cardiocerebrovascular Disease Center, Gyeongsang National University Hospital, Gyeongsang National University School of Medicine, Jinju, Korea
| | - Jinyong Hwang
- Gyeongnam Regional Cardiocerebrovascular Disease Center, Gyeongsang National University Hospital, Gyeongsang National University School of Medicine, Jinju, Korea
| | - Hyun-Woong Park
- Gyeongnam Regional Cardiocerebrovascular Disease Center, Gyeongsang National University Hospital, Gyeongsang National University School of Medicine, Jinju, Korea
| | - Ki Soo Park
- Gyeongnam Regional Cardiocerebrovascular Disease Center, Gyeongsang National University Hospital, Gyeongsang National University School of Medicine, Jinju, Korea
| | - SangHak Yi
- Jeonbuk Regional Cardiocerebrovascular Center, Wonkwang University Hospital, Iksan, Korea
| | - Jae Young Cho
- Jeonbuk Regional Cardiocerebrovascular Center, Wonkwang University Hospital, Iksan, Korea
| | - Nam-Ho Kim
- Jeonbuk Regional Cardiocerebrovascular Center, Wonkwang University Hospital, Iksan, Korea
| | - Kang-Ho Choi
- Gwangju-Jeonnam Regional Cardiocerebrovascular Disease Center, Chonnam National University Medical School and Hospital, Gwangju, Korea
| | - Juhan Kim
- Gwangju-Jeonnam Regional Cardiocerebrovascular Disease Center, Chonnam National University Medical School and Hospital, Gwangju, Korea
| | - Jae-Young Han
- Gwangju-Jeonnam Regional Cardiocerebrovascular Disease Center, Chonnam National University Medical School and Hospital, Gwangju, Korea
| | - Jay Chol Choi
- Jeju Regional Cardiocerebrovascular Disease Center, Jeju National University Hospital, Jeju, Korea
| | - Song-Yi Kim
- Jeju Regional Cardiocerebrovascular Disease Center, Jeju National University Hospital, Jeju, Korea
| | - Joon-Hyouk Choi
- Jeju Regional Cardiocerebrovascular Disease Center, Jeju National University Hospital, Jeju, Korea
| | - Jei Kim
- Daejeon-Chungnam Regional Cardiocerebrovascular Disease Center, Hospital and College of Medicine, Chungnam National University, Daejeon, Korea
| | - Min Kyun Sohn
- Daejeon-Chungnam Regional Cardiocerebrovascular Disease Center, Hospital and College of Medicine, Chungnam National University, Daejeon, Korea
| | - Si Wan Choi
- Daejeon-Chungnam Regional Cardiocerebrovascular Disease Center, Hospital and College of Medicine, Chungnam National University, Daejeon, Korea
| | - Dong-Ick Shin
- Chungbuk Regional Cardiocerebrovascular Disease Center, Chungbuk National University and Hospital, Cheongju, Korea
| | - Sang Yeub Lee
- Chungbuk Regional Cardiocerebrovascular Disease Center, Chungbuk National University and Hospital, Cheongju, Korea
| | - Jang-Whan Bae
- Chungbuk Regional Cardiocerebrovascular Disease Center, Chungbuk National University and Hospital, Cheongju, Korea
| | - Kun Sei Lee
- Department of Preventive Medicine, School of Medicine, Konkuk University, Seoul, Korea
| | - Hee-Joon Bae
- Gyeonggi Regional Cardiocerebrovascular Disease Center, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, Korea.
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Nguyen TH, Son J, Kim S, Cho H, Kim CH, Wang YP, Burch KS, Yang IS, Jeong J, Park JG, Moon SJ, Noh TW. Topological Magnon Band Crossing in Y_{2}Ir_{2}O_{7}. Phys Rev Lett 2021; 127:267203. [PMID: 35029465 DOI: 10.1103/physrevlett.127.267203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Accepted: 11/22/2021] [Indexed: 06/14/2023]
Abstract
Topological magnonic materials have attracted much interest because of the potential for dissipationless spintronic applications. Pyrochlore iridates are theoretically regarded as good candidates for designing topological magnon bands. However, experimental identification of topological magnon bands in pyrochlore iridates remains elusive. We explored this possibility in Y_{2}Ir_{2}O_{7} using Raman spectroscopy to measure both the single-magnon excitations and anomalous phonon shifts. From the single-magnon energies and tight-binding model calculations concerning the phonons, we determined the key parameters in the spin Hamiltonian. These confirm that Y_{2}Ir_{2}O_{7} hosts a nontrivial magnon band topology distinct from other pyrochlore iridate compounds. Our work demonstrates that pyrochlore iridates constitute a system in which the magnon band topology can be tailored and that Raman spectroscopy is a powerful technique to explore magnon band topology.
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Affiliation(s)
- Thi Huyen Nguyen
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul 08826, Republic of Korea
| | - Jaeseok Son
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul 08826, Republic of Korea
| | - Soyeun Kim
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul 08826, Republic of Korea
| | - Hwanbeom Cho
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul 08826, Republic of Korea
| | - Choong H Kim
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul 08826, Republic of Korea
| | - Y P Wang
- Physics Department, Boston College, Boston, Massachusetts 02467, USA
| | - Kenneth S Burch
- Physics Department, Boston College, Boston, Massachusetts 02467, USA
| | - In-Sang Yang
- Department of Physics, Ewha Womans University, Seoul 03760, Republic of Korea
| | - Jaehong Jeong
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul 08826, Republic of Korea
| | - Je-Geun Park
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul 08826, Republic of Korea
- Center for Quantum Materials, Seoul National University, Seoul 08826, Republic of Korea
| | - S J Moon
- Department of Physics, Hanyang University, Seoul 04763, Republic of Korea
| | - T W Noh
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul 08826, Republic of Korea
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Ahn G, Schmehr JL, Porter Z, Wilson SD, Moon SJ. Doping and temperature evolutions of optical response of Sr 3(Ir 1-xRu x) 2O 7. Sci Rep 2020; 10:22340. [PMID: 33339856 PMCID: PMC7749133 DOI: 10.1038/s41598-020-79263-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Accepted: 12/01/2020] [Indexed: 11/09/2022] Open
Abstract
We report on optical spectroscopic study of the Sr3(Ir1-xRux)2O7 system over a wide doping regime. We find that the changes in the electronic structure occur in the limited range of the concentration of Ru ions where the insulator-metal transition occurs. In the insulating regime, the electronic structure associated with the effective total angular momentum Jeff = 1/2 Mott state remains robust against Ru doping, indicating the localization of the doped holes. Upon entering the metallic regime, the Mott gap collapses and the Drude-like peak with strange metallic character appears. The evolution of the electronic structure registered in the optical data can be explained in terms of a percolative insulator-metal transition. The phonon spectra display anomalous doping evolution of the lineshapes. While the phonon modes of the compounds deep in the insulating and metallic regimes are almost symmetric, those of the semiconducting compound with x = 0.34 in close proximity to the doping-driven insulator-metal transition show a pronounced asymmetry. The temperature evolution of the phonon modes of the x = 0.34 compound reveals the asymmetry is enhanced in the antiferromagnetic state. We discuss roles of the S = 1 spins of the Ru ions and charge excitations for the conspicuous lineshape asymmetry of the x = 0.34 compound.
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Affiliation(s)
- Gihyeon Ahn
- Department of Physics, Hanyang University, Seoul, 04763, Republic of Korea
| | - J L Schmehr
- Materials Department, University of California, Santa Barbara, CA, 93106, USA
| | - Z Porter
- Materials Department, University of California, Santa Barbara, CA, 93106, USA
| | - S D Wilson
- Materials Department, University of California, Santa Barbara, CA, 93106, USA
| | - S J Moon
- Department of Physics, Hanyang University, Seoul, 04763, Republic of Korea. .,Research Institute of Natural Science, Hanyang University, Seoul, 04763, Republic of Korea.
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8
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Kim SJ, Zhang X, Cho SB, Kim CH, Park HC, Moon SJ. Uremic solutes of indoxyl sulfate and p-cresol enhance protease-activated receptor-2 expression in vitro and in vivo in keratinocytes. Hum Exp Toxicol 2020; 40:113-123. [PMID: 32757783 DOI: 10.1177/0960327120945758] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
OBJECTIVES Uremic pruritus is common in patients with chronic kidney disease (CKD). The retention of uremic solutes is thought to be associated with uremic pruritus. Meanwhile, activation of protease-activated receptor-2 (PAR-2) has been suggested to play an important role in pruritus. The present study was performed to investigate the effects of uremic solutes on the expression of PAR-2 in the skin. METHODS Indoxyl sulfate (IS), p-cresol (PC), and uremic sera from CKD patients were used to stimulate PAR-2 expression in normal human epidermal keratinocytes (NHEKs). Also, NHEKs were additionally pretreated with soybean trypsin inhibitor to evaluate its inhibitory effect on PAR-2 expression. Patterns of cutaneous PAR-2 expression were investigated in skin samples from five CKD patients and CKD mice. RESULTS In NHEKs, IS, PC, and sera from CKD patients significantly induced PAR-2 mRNA and protein expression. Soybean trypsin inhibitor significantly decreased PAR-2 mRNA and protein expression in NHEKs treated with IS, PC, and CKD sera. NHEKs treated with IS and PC exhibited significant increases in protease activity. Skin from both CKD patients and mice exhibited marked upregulation of PAR-2 expression compared to control skin. CONCLUSIONS Results from the present study suggest that uremic solutes either directly or indirectly affect PAR-2 expression in the skin of CKD subjects, potentially playing an important role in the pathogenesis of uremic pruritus.
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Affiliation(s)
- S J Kim
- Department of Internal Medicine, Institute for Translational & Clinical Research, 395886International St. Mary's Hospital, College of Medicine, Catholic Kwandong University, Incheon, Korea.,The Graduate School, 37991Yonsei University, Seoul, Korea
| | - X Zhang
- Department of Dermatology, 159436Yanbian University Hospital, Yanji, China.,Department of Pathology, 159436Yanbian University Hospital, Yanji, China.,Department of Dermatology and Cutaneous Biology Research Institute, 37991Yonsei University College of Medicine, Seoul, Korea
| | - S B Cho
- Department of Dermatology and Cutaneous Biology Research Institute, 37991Yonsei University College of Medicine, Seoul, Korea
| | - C H Kim
- Department of Internal Medicine, Institute for Translational & Clinical Research, 395886International St. Mary's Hospital, College of Medicine, Catholic Kwandong University, Incheon, Korea
| | - H C Park
- Department of Internal Medicine, 65655Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, Korea
| | - S J Moon
- Department of Internal Medicine, Institute for Translational & Clinical Research, 395886International St. Mary's Hospital, College of Medicine, Catholic Kwandong University, Incheon, Korea
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9
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Sunwoo J, Oh J, Moon SJ, Ji SC, Lee SH, Yu KS, Kim HS, Lee A, Jang IJ. Safety, tolerability, pharmacodynamics and pharmacokinetics of DWP14012, a novel potassium-competitive acid blocker, in healthy male subjects. Aliment Pharmacol Ther 2018; 48:206-218. [PMID: 29863280 DOI: 10.1111/apt.14818] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/17/2018] [Revised: 04/18/2018] [Accepted: 04/30/2018] [Indexed: 12/13/2022]
Abstract
BACKGROUND A novel potassium-competitive acid blocker, DWP14012, is in clinical development as a potential alternative to proton pump inhibitors for the treatment of acid-related diseases. AIMS To evaluate the safety, tolerability, pharmacodynamics and pharmacokinetics of DWP14012 in humans. METHODS A randomised, double-blind, double-dummy, placebo- and active-controlled, single- and multiple-ascending dose (SAD and MAD, respectively) study was conducted in healthy male subjects without Helicobacter pylori infection. Subjects randomly received a single oral dose of 10-320 mg DWP14012, esomeprazole (active comparator) or placebo in the SAD study (n = 72) and once daily doses of 20-160 mg DWP14012, esomeprazole or placebo for 7 days in the MAD study (n = 48; 8:2:2). Tolerability was evaluated using a microRNA-122 assay. Pharmacodynamics were evaluated through 24-hour gastric pH monitoring, and pharmacokinetics were evaluated plasma and urine DWP14012 concentrations. RESULTS DWP14012 was generally well tolerated. The liver toxicity of DWP14012 was not higher than that of placebo after multiple oral administrations. DWP14012 showed rapid and sustained suppression of gastric acid secretion for 24 hours after dosing. Clear dose-response and exposure-response relationships were observed. Plasma concentrations of DWP14012 increased in a dose-proportional manner in the MAD study, whereas in the SAD study, DWP14012 did not significantly accumulate in the plasma. CONCLUSIONS DWP14012 was well tolerated, and showed a rapid and long-lasting gastric acid suppression effect in healthy subjects. These results justify further investigation of DWP14012 in patients with acid-related disorders.
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Affiliation(s)
- J Sunwoo
- Department of Clinical Pharmacology and Therapeutics, Seoul National University College of Medicine and Hospital, Seoul, Korea
| | - J Oh
- Department of Clinical Pharmacology and Therapeutics, Seoul National University College of Medicine and Hospital, Seoul, Korea
| | - S J Moon
- Center for Clinical Pharmacology, Biomedical Research Institute, Chonbuk National University Hospital, Jeonju-so, Korea
| | - S C Ji
- Department of Clinical Pharmacology and Therapeutics, Seoul National University College of Medicine and Hospital, Seoul, Korea
| | - S H Lee
- Department of Clinical Pharmacology and Therapeutics, Seoul National University College of Medicine and Hospital, Seoul, Korea
| | - K-S Yu
- Department of Clinical Pharmacology and Therapeutics, Seoul National University College of Medicine and Hospital, Seoul, Korea
| | - H S Kim
- Daewoong Pharmaceutical Co., Ltd., Yongin, Korea
| | - A Lee
- Daewoong Pharmaceutical Co., Ltd., Yongin, Korea
| | - I-J Jang
- Department of Clinical Pharmacology and Therapeutics, Seoul National University College of Medicine and Hospital, Seoul, Korea
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10
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Kim SY, Kim TY, Sandilands LJ, Sinn S, Lee MC, Son J, Lee S, Choi KY, Kim W, Park BG, Jeon C, Kim HD, Park CH, Park JG, Moon SJ, Noh TW. Charge-Spin Correlation in van der Waals Antiferromagnet NiPS_{3}. Phys Rev Lett 2018; 120:136402. [PMID: 29694193 DOI: 10.1103/physrevlett.120.136402] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2017] [Revised: 09/29/2017] [Indexed: 06/08/2023]
Abstract
Strong charge-spin coupling is found in a layered transition-metal trichalcogenide NiPS_{3}, a van der Waals antiferromagnet, from studies of the electronic structure using several experimental and theoretical tools: spectroscopic ellipsometry, x-ray absorption, photoemission spectroscopy, and density functional calculations. NiPS_{3} displays an anomalous shift in the optical spectral weight at the magnetic ordering temperature, reflecting strong coupling between the electronic and magnetic structures. X-ray absorption, photoemission, and optical spectra support a self-doped ground state in NiPS_{3}. Our work demonstrates that layered transition-metal trichalcogenide magnets are useful candidates for the study of correlated-electron physics in two-dimensional magnetic materials.
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Affiliation(s)
- So Yeun Kim
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University (SNU), Seoul 08826, Republic of Korea
| | - Tae Yun Kim
- Department of Physics and Astronomy, Seoul National University (SNU), Seoul 08826, Republic of Korea
- Center for Theoretical Physics, SNU, Seoul 08826, Republic of Korea
| | - Luke J Sandilands
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University (SNU), Seoul 08826, Republic of Korea
| | - Soobin Sinn
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University (SNU), Seoul 08826, Republic of Korea
| | - Min-Cheol Lee
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University (SNU), Seoul 08826, Republic of Korea
| | - Jaeseok Son
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University (SNU), Seoul 08826, Republic of Korea
| | - Sungmin Lee
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University (SNU), Seoul 08826, Republic of Korea
| | - Ki-Young Choi
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University (SNU), Seoul 08826, Republic of Korea
| | - Wondong Kim
- Korea Research Institute of Standards and Science (KRISS), Daejeon 34113, Republic of Korea
| | - Byeong-Gyu Park
- Pohang Accelerator Laboratory, Pohang University of Science and Technology (POSTECH), Pohang 37673, Republic of Korea
| | - C Jeon
- Advanced Nano-Surface Group, Korea Basic Science Institute (KBSI), Daejeon 34133, Republic of Korea
| | - Hyeong-Do Kim
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University (SNU), Seoul 08826, Republic of Korea
| | - Cheol-Hwan Park
- Department of Physics and Astronomy, Seoul National University (SNU), Seoul 08826, Republic of Korea
- Center for Theoretical Physics, SNU, Seoul 08826, Republic of Korea
| | - Je-Geun Park
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University (SNU), Seoul 08826, Republic of Korea
| | - S J Moon
- Department of Physics, Hanyang University, Seoul 04763, Republic of Korea
| | - T W Noh
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University (SNU), Seoul 08826, Republic of Korea
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11
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Sandilands LJ, Kyung W, Kim SY, Son J, Kwon J, Kang TD, Yoshida Y, Moon SJ, Kim C, Noh TW. Spin-Orbit Coupling and Interband Transitions in the Optical Conductivity of Sr_{2}RhO_{4}. Phys Rev Lett 2017; 119:267402. [PMID: 29328701 DOI: 10.1103/physrevlett.119.267402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2017] [Indexed: 06/07/2023]
Abstract
The prototypical correlated metal Sr_{2}RhO_{4} was studied using optical and photoemission spectroscopy. At low energies and temperatures, the optical data reveal a complex, multicomponent response that on the surface points to an unconventional metallic state in this material. Via a comparison with photoemission, the anomalous optical response may be attributed to an unexpectedly strong interband transition near 180 meV between spin-orbit coupled bands that are nearly parallel along ΓX. This spin-orbit coupling effect is shown to occur in a number of related metallic ruthenates and explains the previously puzzling optical properties reported for these materials.
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Affiliation(s)
- Luke J Sandilands
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul 08826, Republic of Korea
- Measurement Science and Standards, National Research Council Canada, Ottawa, Ottawa K1A 0R6 Canada
| | - Wonshik Kyung
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul 08826, Republic of Korea
| | - So Yeun Kim
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul 08826, Republic of Korea
| | - J Son
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul 08826, Republic of Korea
| | - J Kwon
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul 08826, Republic of Korea
| | - T D Kang
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul 08826, Republic of Korea
| | - Y Yoshida
- National Institute of Advanced Industrial Science and Technology, Tsukuba 305-8568, Japan
| | - S J Moon
- Department of Physics, Hanyang University, Seoul 04763, Republic of Korea
| | - C Kim
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul 08826, Republic of Korea
| | - Tae Won Noh
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul 08826, Republic of Korea
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12
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Nguyen TMH, Sandilands LJ, Sohn CH, Kim CH, Wysocki AL, Yang IS, Moon SJ, Ko JH, Yamaura J, Hiroi Z, Noh TW. Author Correction: Two-magnon scattering in the 5d all-in-all-out pyrochlore magnet Cd 2Os 2O 7. Nat Commun 2017; 8:1702. [PMID: 29150597 PMCID: PMC5693863 DOI: 10.1038/s41467-017-01513-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
A correction to this article has been published and is linked from the HTML version of this article.
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Affiliation(s)
- Thi Minh Hien Nguyen
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul, 151-742, Republic of Korea.,Department of Physics and Astronomy, Seoul National University (SNU), Seoul, 151-742, Republic of Korea
| | - Luke J Sandilands
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul, 151-742, Republic of Korea.,Department of Physics and Astronomy, Seoul National University (SNU), Seoul, 151-742, Republic of Korea.,Measurement Science and Standards, National Research Council of Canada, Ottawa, Ontario, Canada, K1A 0R6
| | - C H Sohn
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul, 151-742, Republic of Korea.,Department of Physics and Astronomy, Seoul National University (SNU), Seoul, 151-742, Republic of Korea
| | - C H Kim
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul, 151-742, Republic of Korea.,Department of Physics and Astronomy, Seoul National University (SNU), Seoul, 151-742, Republic of Korea
| | | | - In-Sang Yang
- Department of Physics and Division of Nano-Sciences, Ewha Womans University, Seoul, 120-750, Republic of Korea
| | - S J Moon
- Department of Physics, Hanyang University, Seoul, 133-791, Republic of Korea
| | - Jae-Hyeon Ko
- Department of Physics, Hallym University, Chuncheon, Gangwondo, 24252, Republic of Korea
| | - J Yamaura
- Materials Research Center for Element Strategy, Tokyo Institute of Technology, Kanagawa, 226-8503, Japan
| | - Z Hiroi
- Institute for Solid State Physics, University of Tokyo, Kashiwa, 277-8581, Japan
| | - Tae Won Noh
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul, 151-742, Republic of Korea. .,Department of Physics and Astronomy, Seoul National University (SNU), Seoul, 151-742, Republic of Korea.
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13
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Nguyen TMH, Sandilands LJ, Sohn CH, Kim CH, Wysocki AL, Yang IS, Moon SJ, Ko JH, Yamaura J, Hiroi Z, Noh TW. Two-magnon scattering in the 5d all-in-all-out pyrochlore magnet Cd 2Os 2O 7. Nat Commun 2017; 8:251. [PMID: 28811471 PMCID: PMC5557926 DOI: 10.1038/s41467-017-00228-w] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2016] [Accepted: 06/12/2017] [Indexed: 11/17/2022] Open
Abstract
5d pyrochlore oxides with all-in-all-out magnetic order are prime candidates for realizing strongly correlated, topological phases of matter. Despite significant effort, a full understanding of all-in-all-out magnetism remains elusive as the associated magnetic excitations have proven difficult to access with conventional techniques. Here we report a Raman spectroscopy study of spin dynamics in the all-in-all-out magnetic state of the 5d pyrochlore Cd2Os2O7. Through a comparison between the two-magnon scattering and spin-wave theory, we confirm the large single ion anisotropy in this material and show that the Dzyaloshinskii-Moriya and exchange interactions play a significant role in the spin-wave dispersions. The Raman data also reveal complex spin-charge-lattice coupling and indicate that the metal-insulator transition in Cd2Os2O7 is Lifshitz-type. Our work establishes Raman scattering as a simple and powerful method for exploring the spin dynamics in 5d pyrochlore magnets.Pyrochlore 5d transition metal oxides are expected to have interesting forms of magnetic order but are hard to study with conventional probes. Here the authors show that Raman scattering can be used to measure magnetic excitations in Cd2Os2O7 and that it exhibits complex spin-charge-lattice coupling.
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Affiliation(s)
- Thi Minh Hien Nguyen
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul, 151-742, Republic of Korea
- Department of Physics and Astronomy, Seoul National University (SNU), Seoul, 151-742, Republic of Korea
| | - Luke J Sandilands
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul, 151-742, Republic of Korea
- Department of Physics and Astronomy, Seoul National University (SNU), Seoul, 151-742, Republic of Korea
- Measurement Science and Standards, National Research Council of Canada, Ottawa, Ontario, Canada, K1A 0R6
| | - C H Sohn
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul, 151-742, Republic of Korea
- Department of Physics and Astronomy, Seoul National University (SNU), Seoul, 151-742, Republic of Korea
| | - C H Kim
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul, 151-742, Republic of Korea
- Department of Physics and Astronomy, Seoul National University (SNU), Seoul, 151-742, Republic of Korea
| | | | - In-Sang Yang
- Department of Physics and Division of Nano-Sciences, Ewha Womans University, Seoul, 03760, Republic of Korea
| | - S J Moon
- Department of Physics, Hanyang University, Seoul, 04763, Republic of Korea
| | - Jae-Hyeon Ko
- Department of Physics, Hallym University, Chuncheon, Gangwondo, 24252, Republic of Korea
| | - J Yamaura
- Materials Research Center for Element Strategy, Tokyo Institute of Technology, Kanagawa, 226-8503, Japan
| | - Z Hiroi
- Institute for Solid State Physics, University of Tokyo, Kashiwa, 277-8581, Japan
| | - Tae Won Noh
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul, 151-742, Republic of Korea.
- Department of Physics and Astronomy, Seoul National University (SNU), Seoul, 151-742, Republic of Korea.
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14
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Sohn CH, Kim CH, Sandilands LJ, Hien NTM, Kim SY, Park HJ, Kim KW, Moon SJ, Yamaura J, Hiroi Z, Noh TW. Strong Spin-Phonon Coupling Mediated by Single Ion Anisotropy in the All-In-All-Out Pyrochlore Magnet Cd_{2}Os_{2}O_{7}. Phys Rev Lett 2017; 118:117201. [PMID: 28368646 DOI: 10.1103/physrevlett.118.117201] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2016] [Indexed: 06/07/2023]
Abstract
Spin-phonon coupling mediated by single ion anisotropy was investigated using optical spectroscopy and first-principles calculations in the all-in-all-out pyrochlore magnet Cd_{2}Os_{2}O_{7}. Clear anomalies were observed in both the phonon frequencies and linewidths at the magnetic ordering temperature. The renormalization of the phonon modes was exceptionally large, signifying the presence of an unconventional magnetoelastic term from large spin-orbit coupling. In addition, the relative phonon frequency shifts show a strong correlation with the modulation of noncubic crystal field by the corresponding lattice distortion. Our observation establishes a new type of spin-phonon coupling through single ion anisotropy, a second-order spin-orbit coupling term, in Cd_{2}Os_{2}O_{7}.
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Affiliation(s)
- C H Sohn
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 151-742, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul 151-742, Republic of Korea
| | - C H Kim
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 151-742, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul 151-742, Republic of Korea
| | - L J Sandilands
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 151-742, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul 151-742, Republic of Korea
| | - N T M Hien
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 151-742, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul 151-742, Republic of Korea
| | - S Y Kim
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 151-742, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul 151-742, Republic of Korea
| | - H J Park
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 151-742, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul 151-742, Republic of Korea
| | - K W Kim
- Department of Physics, Chungbuk National University, Cheongju, Chungbuk 28644, Republic of Korea
| | - S J Moon
- Department of Physics, Hanyang University, Seoul 133-791, Republic of Korea
| | - J Yamaura
- Materials Research Center for Element Strategy, Tokyo Institute of Technology, Kanagawa 226-8503, Japan
| | - Z Hiroi
- ISSP, University of Tokyo, Kashiwa 277-8581, Japan
| | - T W Noh
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 151-742, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul 151-742, Republic of Korea
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15
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Kim KS, Moon SJ, Han SH, Kim KY, Bang IC. Polymorphic microsatellite markers for the endangered fish, the slender shiner Pseudopungtungia tenuicorpa and cross-species amplification across five related species. Genet Mol Res 2016; 15:gmr8496. [PMID: 27706685 DOI: 10.4238/gmr.15038496] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The slender shiner Pseudopungtungia tenuicorpa (Cypriniformes; Cyprinidae; Gobioninae) is an endangered freshwater fish species endemic to Korea. The current strategies for its conservation involve the study of population genetic characters and identification of management units. These strategies require suitable molecular markers to study genetic diversity and genetic structure. Here, we developed nine polymorphic microsatellite markers for P. tenuicorpa for the first time by applying an enrichment method from a size-selected genomic library. The developed microsatellite markers produced a total of 101 alleles (average 11.2). The observed and expected heterozygosities averaged 0.805 and 0.835, respectively. Among the nine identified markers, five markers showed successful amplification across five related Korean Gobioninae species. Thus, the microsatellite markers developed in this study will be useful to establish conservation strategies for both P. tenuicorpa and other related species.
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Affiliation(s)
- K S Kim
- East Sea Environment Research Center, East Sea Research Institute, Korea Institute of Ocean Science & Technology, Uljin, Republic of Korea
| | - S J Moon
- Department of Life Science & Biotechnology, Soonchunhyang University, Asan, Republic of Korea
| | - S H Han
- Department of Life Science & Biotechnology, Soonchunhyang University, Asan, Republic of Korea
| | - K Y Kim
- AquaGenTech Co., Ltd., Busan, Republic of Korea
| | - I C Bang
- Department of Life Science & Biotechnology, Soonchunhyang University, Asan, Republic of Korea
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16
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Kim JH, Kwon SS, Moon SJ, Choe JS, Kwak HI, Lee SY, Le HJ, Kim JY. Reliability of classification of ring and little finger carpometacarpal joint fracture subluxations: a comparison between two-dimensional computed tomography and three-dimensional computed tomography classifications. J Hand Surg Eur Vol 2016; 41:448-52. [PMID: 26329885 DOI: 10.1177/1753193415602589] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/26/2014] [Accepted: 06/09/2015] [Indexed: 02/03/2023]
Abstract
The aims of this study were to develop a classification for ring and little finger carpometacarpal joint fracture subluxations based on three-dimensional computed tomography images and evaluate the inter- and intraobserver reliability of the three-dimensional computed tomography classification. A retrospective review was performed of 30 cases of ring and little finger carpometacarpal joint fracture subluxations from 2005 to 2013. We classified ring and little finger carpometacarpal joint fracture subluxations into three types based on three-dimensional computed tomography images. An orthopaedic surgeon with 2 years of experience, a consultant hand surgeon with 8 years of experience, and a consultant radiologist with 9 years of experience, who were completely blind to the treatment algorithm, evaluated 30 cases twice at a 2-week interval using our new classification based on three-dimensional computed tomography images and the other classification based on two-dimensional computed tomography images. Our three-dimensional computed tomography classification showed almost perfect interobserver and intraobserver reliability and resulted in a better level of agreement than two-dimensional computed tomography classification.
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Affiliation(s)
- J H Kim
- Department of Orthopedic Surgery, Seonam University College of Medicine, Myongji Hospital, Goyang - Si, Korea
| | - S-S Kwon
- Biomedical Research Institute, Seoul National University Bundang Hospital, Seoul, Korea
| | - S J Moon
- Department of Orthopedic Surgery, Seonam University College of Medicine, Myongji Hospital, Goyang - Si, Korea
| | - J S Choe
- Department of Orthopedic Surgery, Seonam University College of Medicine, Myongji Hospital, Goyang - Si, Korea
| | - H I Kwak
- Department of Orthopedic Surgery, Seonam University College of Medicine, Myongji Hospital, Goyang - Si, Korea
| | - S Y Lee
- Department of Orthopedic Surgery, Ewha Womans University Mokdong Hospital
| | - H J Le
- Department of Radiology, Konkuk University School of Medicine
| | - J Y Kim
- Department of Orthopedic Surgery, Seonam University College of Medicine, Myongji Hospital, Goyang - Si, Korea
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17
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Sohn CH, Jeong H, Jin H, Kim S, Sandilands LJ, Park HJ, Kim KW, Moon SJ, Cho DY, Yamaura J, Hiroi Z, Noh TW. Optical Spectroscopic Studies of the Metal-Insulator Transition Driven by All-In-All-Out Magnetic Ordering in 5d Pyrochlore Cd(2)Os(2)O(7). Phys Rev Lett 2015; 115:266402. [PMID: 26765010 DOI: 10.1103/physrevlett.115.266402] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2015] [Indexed: 06/05/2023]
Abstract
We investigated the metal-insulator transition (MIT) driven by all-in-all-out (AIAO) antiferromagnetic ordering in the 5d pyrochlore Cd(2)Os(2)O(7) using optical spectroscopy and first-principles calculations. We showed that the temperature evolution in the band-gap edge and free carrier density were consistent with rigid upward (downward) shifts of electron (hole) bands, similar to the case of Lifshitz transitions. The delicate relationship between the band gap and free carrier density provides experimental evidence for the presence of an AIAO metallic phase, a natural consequence of such MITs. The associated spectral weight change at high energy and first-principles calculations further support the origin of the MIT from the band shift near the Fermi level. Our data consistently support that the MIT induced by AIAO ordering in Cd(2)Os(2)O(7) is not close to a Slater type but instead to a Lifshitz type.
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Affiliation(s)
- C H Sohn
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University (SNU), Seoul 08826, Republic of Korea
| | - Hogyun Jeong
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
| | - Hosub Jin
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University (SNU), Seoul 08826, Republic of Korea
- Department of Physics, Ulsan National Institute of Science and Technology, Ulsan 44919, Republic of Korea
| | - Soyeon Kim
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University (SNU), Seoul 08826, Republic of Korea
| | - L J Sandilands
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University (SNU), Seoul 08826, Republic of Korea
| | - H J Park
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University (SNU), Seoul 08826, Republic of Korea
| | - K W Kim
- Department of Physics, Chungbuk National University, Cheongju, Chungbuk 28644, Republic of Korea
| | - S J Moon
- Department of Physics, Hanyang University, Seoul 04763, Republic of Korea
| | - Deok-Yong Cho
- Department of Physics, Chonbuk National University, Jeonju 54896, Republic of Korea
| | - J Yamaura
- Materials Research Center for Element Strategy, Tokyo Institute of Technology, Kanagawa 226-8503, Japan
| | - Z Hiroi
- ISSP, University of Tokyo, Kashiwa 277-8581, Japan
| | - T W Noh
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University (SNU), Seoul 08826, Republic of Korea
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Song S, Lee S, Jeon S, Park JG, Moon SJ. Infrared probe of spin-phonon coupling in antiferromagnetic honeycomb lattice compound Li₂MnO₃. J Phys Condens Matter 2015; 27:485604. [PMID: 26571347 DOI: 10.1088/0953-8984/27/48/485604] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We investigated temperature-dependent infrared-active phonon modes of honeycomb Li2MnO3 which shows an antiferromagnetic transition at T(N) = 36 K. In the far-infrared frequency region, we observed fourteen phonon modes. We obtained the temperature dependence of each phonon mode from the analysis of optical conductivity spectra by using the Lorentz and the Fano-type oscillator models. We found that the resonance frequencies of nine phonon modes showed an anomalous behavior near T(N) that should be attributed to the spin-phonon coupling. We calculated the magnitude of the spin-phonon coupling constant from the shift in the resonance frequencies of the phonon modes below T(N). Our results suggest that Li2MnO3 is weakly frustrated and that spin-phonon coupling plays a role in antiferromagnetic ordering.
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Affiliation(s)
- Seungjae Song
- Department of Physics, Hanyang University, Seoul 133-791, Korea
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Lee SY, Kwon SS, Kim HS, Yoo JH, Kim J, Kim JY, Min BC, Moon SJ, Sung KH. Reliability and validity of lower extremity computed tomography as a screening tool for osteoporosis. Osteoporos Int 2015; 26:1387-94. [PMID: 25592134 DOI: 10.1007/s00198-014-3013-x] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/11/2014] [Accepted: 12/17/2014] [Indexed: 01/22/2023]
Abstract
UNLABELLED We evaluated the correlation between central bone mineral density (BMD) and peripheral bone attenuation using lower extremity computed tomography (CT). A good correlation was found between lower extremity CT and central BMD suggesting that CT is useful for screening osteoporosis, and that peripheral bone attenuation adequately reflects central BMD. INTRODUCTION This study aimed to evaluate the reliability and validity of CT as a screening tool for osteoporosis and to estimate the correlation between central BMD and peripheral bone attenuation using lower extremity CT. METHODS In total, 292 patients who underwent a lower extremity, lumbar spine, or abdomen and pelvic CT scan within a 3-month interval of a dual-energy X-ray absorptiometry (DEXA) examination were included. Following reliability testing, bone attenuation of the L1, L2, L3, L4, femoral head, femoral neck, greater trochanter, distal femur, proximal tibia, distal tibia, and talus was measured by placing a circular region of interest on the central part of each bony region on a coronal CT image. Partial correlation was used to assess the correlation between CT and DEXA after adjusting for age and body mass index. RESULTS In terms of reliability, all bone attenuation measurements, except the femoral neck, showed good to excellent interobserver reliability (intraclass correlation coefficients, 0.691-0.941). In terms of validity, bone attenuation of the L1 to L4, femoral neck, and greater trochanter on CT showed significant correlations with BMD of each area on DEXA (correlation coefficients, 0.399-0.613). Bone attenuation of the distal tibia and talus on CT showed significant correlations with BMD of all parts on DEXA (correlation coefficients, 0.493-0.581 for distal tibia, 0.396-0.579 for talus). CONCLUSION Lower extremity CT is a useful screening tool for osteoporosis, and peripheral bone attenuation on lower extremity CT adequately reflects central BMD on DEXA.
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Affiliation(s)
- S Y Lee
- Department of Orthopaedic Surgery, Ewha Womans University Mokdong Hospital, Seoul, South Korea
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20
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Jeong DW, Choi HC, Kim CH, Chang SH, Sohn CH, Park HJ, Kang TD, Cho DY, Baek SH, Eom CB, Shim JH, Yu J, Kim KW, Moon SJ, Noh TW. Temperature evolution of itinerant ferromagnetism in SrRuO3 probed by optical spectroscopy. Phys Rev Lett 2013; 110:247202. [PMID: 25165956 DOI: 10.1103/physrevlett.110.247202] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2013] [Indexed: 06/03/2023]
Abstract
The temperature (T) dependence of the optical conductivity spectra σ(ω) of a single crystal SrRuO(3) thin film is studied over a T range from 5 to 450 K. We observed significant T dependence of the spectral weights of the charge transfer and interband d-d transitions across the ferromagnetic Curie temperature (T(c) ∼ 150 K). Such T dependence was attributed to the increase in the Ru spin moment, which is consistent with the results of density functional theory calculations. T scans of σ(Ω,T) at fixed frequencies Ω reveal a clear T(2) dependence below T(c), demonstrating that the Stoner mechanism is involved in the evolution of the electronic structure. In addition, σ(Ω,T) continues to evolve at temperatures above T(c), indicating that the local spin moment persists in the paramagnetic state. This suggests that SrRuO(3) is an intriguing oxide system with itinerant ferromagnetism.
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Affiliation(s)
- D W Jeong
- Center for Functional Interfaces of Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 151-747, Korea and Department of Physics and Astronomy, Seoul National University, Seoul 151-747, Korea
| | - Hong Chul Choi
- Department of Chemistry, Pohang University of Science and Technology, Pohang 790-784, Korea
| | - Choong H Kim
- Department of Physics and Astronomy, Seoul National University, Seoul 151-747, Korea
| | - Seo Hyoung Chang
- Center for Functional Interfaces of Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 151-747, Korea and Department of Physics and Astronomy, Seoul National University, Seoul 151-747, Korea
| | - C H Sohn
- Center for Functional Interfaces of Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 151-747, Korea and Department of Physics and Astronomy, Seoul National University, Seoul 151-747, Korea
| | - H J Park
- Center for Functional Interfaces of Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 151-747, Korea and Department of Physics and Astronomy, Seoul National University, Seoul 151-747, Korea
| | - T D Kang
- Center for Functional Interfaces of Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 151-747, Korea and Department of Physics and Astronomy, Seoul National University, Seoul 151-747, Korea
| | - Deok-Yong Cho
- Center for Functional Interfaces of Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 151-747, Korea and Department of Physics and Astronomy, Seoul National University, Seoul 151-747, Korea
| | - S H Baek
- Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - C B Eom
- Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - J H Shim
- Department of Chemistry, Pohang University of Science and Technology, Pohang 790-784, Korea and Division of Advanced Nuclear Engineering, Pohang University of Science and Technology, Pohang 790-784, Korea
| | - J Yu
- Department of Physics and Astronomy, Seoul National University, Seoul 151-747, Korea
| | - K W Kim
- Department of Physics, Chungbuk National University, Cheongju 361-763, Korea
| | - S J Moon
- Department of Physics, Hanyang University, Seoul 133-791, Korea
| | - T W Noh
- Center for Functional Interfaces of Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 151-747, Korea and Department of Physics and Astronomy, Seoul National University, Seoul 151-747, Korea
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21
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Moon SJ, Schafgans AA, Tanatar MA, Prozorov R, Thaler A, Canfield PC, Sefat AS, Mandrus D, Basov DN. Interlayer coherence and superconducting condensate in the c-axis response of optimally doped Ba(Fe(1-x)Co(x))2As2 high-T(c) superconductor using infrared spectroscopy. Phys Rev Lett 2013; 110:097003. [PMID: 23496739 DOI: 10.1103/physrevlett.110.097003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2012] [Indexed: 06/01/2023]
Abstract
We report on the infrared studies of the interlayer charge dynamics of a prototypical pnictide superconductor Ba(Fe(0.926)Co(0.074))(2)As(2). We succeeded in probing the intrinsic interlayer response by performing infrared experiments on the crystals with a cleaved ac surface. Our experiments identify the coexistence of the suppression of the electronic spectral weight and the development of a coherent Drude-like response in the normal state. The formation of the interlayer condensate is clearly observed in the superconducting state and appears to be linked to coherent contribution to the normal-state conductivity.
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Affiliation(s)
- S J Moon
- Department of Physics, University of California, San Diego, La Jolla, California 92093, USA
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22
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Moon SJ, Schafgans AA, Kasahara S, Shibauchi T, Terashima T, Matsuda Y, Tanatar MA, Prozorov R, Thaler A, Canfield PC, Sefat AS, Mandrus D, Basov DN. Infrared measurement of the pseudogap of P-doped and Co-doped high-temperature BaFe2As2 superconductors. Phys Rev Lett 2012; 109:027006. [PMID: 23030200 DOI: 10.1103/physrevlett.109.027006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2011] [Indexed: 06/01/2023]
Abstract
We report on infrared studies of charge dynamics in a prototypical pnictide system: the BaFe2As2 family. Our experiments have identified hallmarks of the pseudogap state in the BaFe2As2 system that mirror the spectroscopic manifestations of the pseudogap in the cuprates. The magnitude of the infrared pseudogap is in accord with that of the spin-density-wave gap of the parent compound. By monitoring the superconducting gap of both P- and Co-doped compounds, we find that the infrared pseudogap is unrelated to superconductivity. The appearance of the pseudogap is found to correlate with the evolution of the antiferromagnetic fluctuations associated with the spin-density-wave instability. The strong-coupling analysis of infrared data further reveals the interdependence between the magnetism and the pseudogap in the iron pnictides.
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Affiliation(s)
- S J Moon
- Department of Physics, University of California, San Diego, La Jolla, California 92093, USA
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Schafgans AA, Moon SJ, Pursley BC, LaForge AD, Qazilbash MM, Sefat AS, Mandrus D, Haule K, Kotliar G, Basov DN. Electronic correlations and unconventional spectral weight transfer in the high-temperature pnictide BaFe(2-x)Co(x)As(2) superconductor using infrared spectroscopy. Phys Rev Lett 2012; 108:147002. [PMID: 22540817 DOI: 10.1103/physrevlett.108.147002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2011] [Indexed: 05/31/2023]
Abstract
We report an infrared optical study of the pnictide high-temperature superconductor BaFe(1.84)Co(0.16)As(2) and its parent compound BaFe(2)As(2). We demonstrate that electronic correlations are moderately strong and do not change across the spin-density wave transition or with doping. By examining the energy scale and direction of spectral weight transfer, we argue that Hund's coupling J is the primary mechanism that gives rise to correlations.
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Affiliation(s)
- A A Schafgans
- Department of Physics, University of California, San Diego, La Jolla, California 92093, USA.
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24
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Moon SJ, Homes CC, Akrap A, Xu ZJ, Wen JS, Lin ZW, Li Q, Gu GD, Basov DN. Incoherent c-axis interplane response of the iron chalcogenide FeTe(0.55)Se(0.45) superconductor from infrared spectroscopy. Phys Rev Lett 2011; 106:217001. [PMID: 21699329 DOI: 10.1103/physrevlett.106.217001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2010] [Indexed: 05/31/2023]
Abstract
We report on the interplane c-axis electronic response of FeTe(0.55)Se(0.45) investigated by infrared spectroscopy. We find that the normal-state c-axis electronic response of FeTe(0.55)Se(0.45) is incoherent and bears significant similarities to those of mildly underdoped cuprates. The c-axis optical conductivity σ(c)(ω) of FeTe(0.55)Se(0.45) does not display well-defined Drude response at all temperatures. As temperature decreases, σ(c)(ω) is continuously suppressed. The incoherent c-axis response is found to be related to the strong dissipation in the ab-plane transport: a pattern that holds true for various correlated materials as well as FeTe(0.55)Se(0.45).
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Affiliation(s)
- S J Moon
- Department of Physics, University of California, San Diego, La Jolla, California 92093, USA.
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25
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Dubroka A, Rössle M, Kim KW, Malik VK, Munzar D, Basov DN, Schafgans AA, Moon SJ, Lin CT, Haug D, Hinkov V, Keimer B, Wolf T, Storey JG, Tallon JL, Bernhard C. Evidence of a precursor superconducting phase at temperatures as high as 180 K in RBa2Cu3O(7-δ) (R=Y, Gd, Eu) superconducting crystals from infrared spectroscopy. Phys Rev Lett 2011; 106:047006. [PMID: 21405352 DOI: 10.1103/physrevlett.106.047006] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2010] [Indexed: 05/30/2023]
Abstract
We show that a multilayer analysis of the infrared c-axis response of RBa2Cu3O(7-δ) (R=Y, Gd, Eu) provides important new information about the anomalous normal-state properties of underdoped cuprate high temperature superconductors. In addition to competing correlations which give rise to a pseudogap that depletes the low-energy electronic states below T*≫T(c), it enables us to identify the onset of a precursor superconducting state below T(ons)>T(c). We map out the doping phase diagram of T(ons) which reaches a maximum of 180 K at strong underdoping and present magnetic field dependent data which confirm our conclusions.
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Affiliation(s)
- A Dubroka
- University of Fribourg, Department of Physics, Fribourg, Switzerland
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26
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Jang SY, Kim H, Moon SJ, Choi WS, Jeon BC, Yu J, Noh TW. The electronic structure of epitaxially stabilized 5d perovskite Ca(1-x)Sr(x)IrO3 (x = 0, 0.5, and 1) thin films: the role of strong spin-orbit coupling. J Phys Condens Matter 2010; 22:485602. [PMID: 21406751 DOI: 10.1088/0953-8984/22/48/485602] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
We have investigated the electronic structure of meta-stable perovskite Ca(1 - x)Sr(x)IrO(3)(x = 0, 0.5, and 1) thin films using transport measurements, optical spectroscopy, and first-principles calculations. We artificially fabricated the perovskite phase of Ca(1 - x)Sr(x)IrO(3), which has a hexagonal or post-perovskite crystal structure in bulk form, by growing epitaxial thin films on perovskite GdScO(3) substrates using an epi-stabilization technique. The transport properties of the perovskite Ca(1 - x)Sr(x)IrO(3) films systematically change from nearly insulating (or semi-metallic) for x = 0 to weakly metallic for x = 1. Due to the extended wavefunctions, 5d electrons are usually delocalized. However, the strong spin-orbit coupling in Ca(1 - x)Sr(x)IrO(3) results in the formation of effective total angular momentum J(eff) = 1/2 and 3/2 states, which puts Ca(1 - x)Sr(x)IrO(3) in the vicinity of a metal-insulator phase boundary. As a result, the electrical properties of the Ca(1 - x)Sr(x)IrO(3) films are found to be sensitive to x and strain.
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Affiliation(s)
- S Y Jang
- ReCFI, Department of Physics and Astronomy, Seoul National University, Seoul, Republic of Korea
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27
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Lee JA, Kim CK, Jahng GH, Hwang LK, Cho YW, Kim YJ, Lee WH, Moon SJ, Cho AR, Bahn GH. A pilot study of brain activation in children with trichotillomania during a visual-tactile symptom provocation task: a functional magnetic resonance imaging study. Prog Neuropsychopharmacol Biol Psychiatry 2010; 34:1250-8. [PMID: 20637819 DOI: 10.1016/j.pnpbp.2010.06.031] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/01/2010] [Revised: 06/30/2010] [Accepted: 06/30/2010] [Indexed: 01/25/2023]
Abstract
OBJECTIVES In order to reveal the etiology and pathophysiology of trichotillomania (TTM), it is necessary to investigate which brain regions are involved in TTM, but limited knowledge exists regarding the neurobiology of TTM and the available functional neuroimaging studies of TTM are little. The purpose of the present study was to investigate the specific brain regions involved in the pathophysiology of TTM with symptom provocation task using functional magnetic resonance imaging (fMRI) for children and adolescents with TTM. METHODS Pediatric subjects who met the DSM-IV TR criteria for TTM (n=9) and age-, sex-, handedness-, IQ matched healthy controls (HC) (n=10), ages 9 to 17 years, were recruited for two fMRI experiments; symptom provocation of Visual Only (VO) and Visual and Tactile (VT). They were scanned while viewing two alternating blocks of symptom provocation (S) and neutral (N) movies. RESULTS Random effects between-group analysis revealed significant activation in left temporal cortex(including middle and superior temporal gyrus), dorsal posterior cingulate gyrus, and putamen for the contrast S>N in TTM subjects versus HC subjects during the VO session. And TTM subjects demonstrated higher activity in the precuneus and dorsal posterior cingulate gyrus to the contrast S>N during the VT session. CONCLUSIONS This study provided an objective whole-brain-based analysis that directed researchers to areas that were abnormal in TTM. Using the symptom provocation tasks, we found significant differences in regional brain function between pediatric TTM and HC subjects. However, in the face of modest statistical power, our preliminary findings in TTM need to be replicated in a larger sample. As the functional neuroanatomic circuits involved in TTM remain largely unexplored, future functional neuroimaging studies using other various paradigms may help investigate the neuroanatomic abnormalities of TTM.
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Affiliation(s)
- J A Lee
- Department of Psychiatry, Subdivision of Child & Adolescent Psychiatry, School of Medicine, Kyung Hee University, 1 Hoegi-dong, Dongdaemoon-gu, Seoul 130-701, Republic of Korea
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Jeon BC, Kim CH, Moon SJ, Choi WS, Jeong H, Lee YS, Yu J, Won CJ, Jung JH, Hur N, Noh TW. Electronic structure of double perovskite A2FeReO6 (A = Ba and Ca): interplay between spin-orbit interaction, electron correlation, and lattice distortion. J Phys Condens Matter 2010; 22:345602. [PMID: 21403258 DOI: 10.1088/0953-8984/22/34/345602] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
We have investigated the electronic structure of double perovskites, Ba(2)FeReO(6) (metallic) and Ca(2)FeReO(6) (insulating) using optical and x-ray absorption spectroscopy. By comparing the experimental results with the density functional theory calculations, we found that the electronic structure of Ba(2)FeReO(6) could be determined from the interaction of the electron correlation and spin-orbit coupling. On the other hand, for Ca(2)FeReO(6), the lattice distortion and electron correlation are important in determining the electronic structure. Additionally, the insulating gap in Ca(2)FeReO(6) is realized by the spin-orbit coupling. Our work shows that the subtle interplay of the spin-orbit interaction, electron correlation, and lattice distortion should be taken into account to understand the electronic structure of the 5d transition metal oxides.
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Affiliation(s)
- B C Jeon
- ReCFI, Department of Physics and Astronomy, Seoul National University, Seoul, Korea
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Xu F, Moon SJ, Emre AE, Turali ES, Song YS, Hacking SA, Nagatomi J, Demirci U. A droplet-based building block approach for bladder smooth muscle cell (SMC) proliferation. Biofabrication 2010; 2:014105. [PMID: 20811120 DOI: 10.1088/1758-5082/2/1/014105] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Tissue engineering based on building blocks is an emerging method to fabricate 3D tissue constructs. This method requires depositing and assembling building blocks (cell-laden microgels) at high throughput. The current technologies (e.g., molding and photolithography) to fabricate microgels have throughput challenges and provide limited control over building block properties (e.g., cell density). The cell-encapsulating droplet generation technique has potential to address these challenges. In this study, we monitored individual building blocks for viability, proliferation and cell density. The results showed that (i) SMCs can be encapsulated in collagen droplets with high viability (>94.2 +/- 3.2%) for four cases of initial number of cells per building block (i.e. 7 +/- 2, 16 +/- 2, 26 +/- 3 and 37 +/- 3 cells/building block). (ii) Encapsulated SMCs can proliferate in building blocks at rates that are consistent (1.49 +/- 0.29) across all four cases, compared to that of the controls. (iii) By assembling these building blocks, we created an SMC patch (5 mm x 5 mm x 20 microm), which was cultured for 51 days forming a 3D tissue-like construct. The histology of the cultured patch was compared to that of a native rat bladder. These results indicate the potential of creating 3D tissue models at high throughput in vitro using building blocks.
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Affiliation(s)
- F Xu
- Department of Medicine, Bio-Acoustic-MEMS in Medicine (BAMM) Laboratory, Center for Biomedical Engineering, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
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30
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Seo SSA, Han MJ, Hassink GWJ, Choi WS, Moon SJ, Kim JS, Susaki T, Lee YS, Yu J, Bernhard C, Hwang HY, Rijnders G, Blank DHA, Keimer B, Noh TW. Two-dimensional confinement of 3d{1} electrons in LaTiO_{3}/LaAlO{3} multilayers. Phys Rev Lett 2010; 104:036401. [PMID: 20366664 DOI: 10.1103/physrevlett.104.036401] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2009] [Indexed: 05/29/2023]
Abstract
We report spectroscopic ellipsometry measurements of the anisotropy of the interband transitions parallel and perpendicular to the planes of (LaTiO3)n(LaAlO3)5 multilayers with n=1-3. These provide direct information about the electronic structure of the two-dimensional (2D) 3d{1} state of the Ti ions. In combination with local density approximation, including a Hubbard U calculation, we suggest that 2D confinement in the TiO2 slabs lifts the degeneracy of the t{2g} states leaving only the planar d{xy} orbitals occupied. We outline that these multilayers can serve as a model system for the study of the t{2g} 2D Hubbard model.
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Affiliation(s)
- S S A Seo
- Department of Physics and Astronomy, Seoul National University, Seoul 151-747, Korea.
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Lee SM, Jeong YH, Kim HM, Park HY, Yoon D, Kim DH, Saeki S, Moon SJ, Kang MJ. Presenilin enhancer-2 (PSENEN), a component of the gamma-secretase complex, is involved in adipocyte differentiation. Domest Anim Endocrinol 2009; 37:170-80. [PMID: 19592191 DOI: 10.1016/j.domaniend.2009.05.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/12/2009] [Revised: 05/20/2009] [Accepted: 05/23/2009] [Indexed: 11/16/2022]
Abstract
This study was conducted to identify genes expressed during adipocyte differentiation of bovine intramuscular fibroblast-like cells using differential display reverse-transcriptase polymerase chain reaction. The presenilin enhancer-2 (PSENEN) gene was found to be down-regulated during adipocyte differentiation of bovine intramuscular fibroblast-like cells. The ectopic expression of bovine PSENEN in 3T3-L1 reduced adipogenesis and the inhibition of endogenous PSENEN by siRNA induced adipogenesis on d 4 of adipocyte differentiation of 3T3-L1 cells. Interestingly, the expression of gamma-secretase complex gene-related Notch signaling was decreased at d 2 and d 4 during adipocyte differentiation. In addition, expression of the Notch-signaling genes (Notch-1, Hes-1, Pref-1, adipsin) was regulated during adipocyte differentiation by regulation of PSENEN expression. These results suggest that PSENEN plays an important role in adipocyte differentiation and that Notch signaling is involved in adipogenesis.
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Affiliation(s)
- S M Lee
- Department of Animal Science, College of Agriculture and Life Science, Institute of Agricultural Science and Technology, Chonnam National University, Gwangju 500-757, Korea
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32
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Moon SJ, Jin H, Kim KW, Choi WS, Lee YS, Yu J, Cao G, Sumi A, Funakubo H, Bernhard C, Noh TW. Dimensionality-controlled insulator-metal transition and correlated metallic state in 5d transition metal oxides Sr n+1Ir nO3n+1 (n=1, 2, and infinity). Phys Rev Lett 2008; 101:226402. [PMID: 19113493 DOI: 10.1103/physrevlett.101.226402] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2008] [Indexed: 05/27/2023]
Abstract
We investigated the electronic structures of the 5d Ruddlesden-Popper series Sr n+1Ir nO3n+1 (n=1, 2, and infinity) using optical spectroscopy and first-principles calculations. As 5d orbitals are spatially more extended than 3d or 4d orbitals, it has been widely accepted that correlation effects are minimal in 5d compounds. However, we observed a Mott insulator-metal transition with a change of bandwidth as we increased n. In addition, the artificially synthesized perovskite SrIrO3 showed a very large mass enhancement of about 6, indicating that it was in a correlated metallic state.
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Affiliation(s)
- S J Moon
- ReCOE & FPRD, Department of Physics and Astronomy, Seoul National University, Seoul 151-747, Korea
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33
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Yum JH, Moon SJ, Humphry-Baker R, Walter P, Geiger T, Nüesch F, Grätzel M, Nazeeruddin MDK. Effect of coadsorbent on the photovoltaic performance of squaraine sensitized nanocrystalline solar cells. Nanotechnology 2008; 19:424005. [PMID: 21832665 DOI: 10.1088/0957-4484/19/42/424005] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The effect of chenodeoxycholic acid as the coadsorbent with a squaraine sensitizer on TiO(2) nanocrystalline solar cells was investigated, and it was found that the coadsorbent prevents the squaraine sensitizer from aggregating on the TiO(2) nanoparticles but reduces dye loading leading to an interdependent photovoltaic performance. Analysis of the absorption spectra, and incident monochromatic photon-to-current conversion efficiency data showed that the load of squaraine sensitizer as well as the appearance of H-aggregates is strongly dependent on the molar concentration of chenodeoxycholic acid coadsorbent. The open circuit voltage of the solar cells with chenodeoxycholic acid increases due to the enhanced electron lifetime in the TiO(2) nanoparticles coupled with the band edge shift of TiO(2) to negative potentials.
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Affiliation(s)
- J H Yum
- Laboratory for Photonics and Interfaces, Institute of Chemical Sciences and Engineering, School of basic Sciences, Swiss Federal Institute of Technology, CH-1015 Lausanne, Switzerland
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Dunn J, Magee EW, Shepherd R, Chen H, Hansen SB, Moon SJ, Brown GV, Gu MF, Beiersdorfer P, Purvis MA. High resolution soft x-ray spectroscopy of low Z K-shell emission from laser-produced plasmas. Rev Sci Instrum 2008; 79:10E314. [PMID: 19044476 DOI: 10.1063/1.2968704] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
A large radius, R=44.3 m, high resolution grating spectrometer (HRGS) with 2400 lines/mm variable line spacing has been designed for laser-produced plasma experiments conducted at the Lawrence Livermore National Laboratory Jupiter Laser Facility. The instrument has been run with a low-noise, charge-coupled device detector to record high signal-to-noise spectra in the 10-50 A wavelength range. The instrument can be run with a 10-20 microm wide slit to achieve the best spectral resolving power, approaching 1000 and similar to crystal spectrometers at 12-20 A, or in slitless operation with a small symmetrical emission source. We describe preliminary spectra emitted from various H-like and He-like low Z ion plasmas heated by 100-500 ps (full width at half maximum), 527 nm wavelength laser pulses. This instrument can be developed as a useful spectroscopy platform relevant to laboratory-based astrophysics as well as high energy density plasma studies.
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Affiliation(s)
- J Dunn
- Lawrence Livermore National Laboratory, Livermore, California 94551, USA.
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35
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Kim BJ, Jin H, Moon SJ, Kim JY, Park BG, Leem CS, Yu J, Noh TW, Kim C, Oh SJ, Park JH, Durairaj V, Cao G, Rotenberg E. Novel Jeff=1/2 Mott state induced by relativistic spin-orbit coupling in Sr2IrO4. Phys Rev Lett 2008; 101:076402. [PMID: 18764560 DOI: 10.1103/physrevlett.101.076402] [Citation(s) in RCA: 352] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2008] [Indexed: 05/23/2023]
Abstract
We investigated the electronic structure of 5d transition-metal oxide Sr2IrO4 using angle-resolved photoemission, optical conductivity, x-ray absorption measurements, and first-principles band calculations. The system was found to be well described by novel effective total angular momentum Jeff states, in which the relativistic spin-orbit coupling is fully taken into account under a large crystal field. Despite delocalized Ir 5d states, the Jeff states form such narrow bands that even a small correlation energy leads to the Jeff=1/2 Mott ground state with unique electronic and magnetic behaviors, suggesting a new class of Jeff quantum spin driven correlated-electron phenomena.
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Affiliation(s)
- B J Kim
- School of Physics and Astronomy, Seoul National University, Seoul 151-747, Korea
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36
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Moon SJ, Choi WS, Kim SJ, Lee YS, Khalifah PG, Mandrus D, Noh TW. Orbital-driven electronic structure changes and the resulting optical anisotropy of the quasi-two-dimensional spin gap compound La4Ru2O10. Phys Rev Lett 2008; 100:116404. [PMID: 18517806 DOI: 10.1103/physrevlett.100.116404] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2007] [Indexed: 05/26/2023]
Abstract
We investigated the electronic response of the quasi-two-dimensional spin gap compound La4Ru2O10 using optical spectroscopy. We observed the drastic changes in the optical spectra as the temperature decreased, resulting in anisotropy in the electronic structure of the spin-singlet ground state. Using the orbital-dependent hopping analysis, we found that orbital ordering plays a crucial role in forming the spin gap state in the non-one-dimensional material.
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Affiliation(s)
- S J Moon
- ReCOE and FPRD, Department of Physics and Astronomy, Seoul National University, Seoul 151-747, Korea
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Li JJ, Kwak SJ, Jung DS, Kim JJ, Yoo TH, Ryu DR, Han SH, Choi HY, Lee JE, Moon SJ, Kim DK, Han DS, Kang SW. Podocyte biology in diabetic nephropathy. Kidney Int 2007:S36-42. [PMID: 17653209 DOI: 10.1038/sj.ki.5002384] [Citation(s) in RCA: 143] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Glomerular visceral epithelial cells, namely podocytes, are highly specialized cells and give rise to primary processes, secondary processes, and finally foot processes. The foot processes of neighboring podocytes interdigitate, leaving between them filtration slits. These are bridged by an extracellular substance, known as the slit diaphragm, which plays a major role in establishing size-selective barrier to protein loss. Furthermore, podocytes are known to synthesize matrix molecules to the glomerular basement membrane (GBM), including type IV collagen, laminin, entactin, and agrin. Because diabetic nephropathy is clinically characterized by proteinuria and pathologically by glomerular hypertrophy and GBM thickening with foot process effacement, podocytes have been the focus in the field of research on diabetic nephropathy. As a result, many investigations have demonstrated that the diabetic milieu per se, hemodynamic changes, and local growth factors such as transforming growth factor-beta and angiotensin II, which are considered mediators in the pathogenesis of diabetic nephropathy, induce directly and/or indirectly hypertrophy, apoptosis, and structural changes, and increase type IV collagen synthesis in podocytes. This review explores some of the structural and functional changes of podocytes under diabetic conditions and their role in the development and progression of diabetic nephropathy.
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Affiliation(s)
- J J Li
- Department of Internal Medicine, Nephrology and Dialysis Unit, The Affiliated Hospital, YanBian University Medical College, JiLin, China
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38
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Lee JS, Moon SJ, Yang BJ, Yu J, Schade U, Yoshida Y, Ikeda SI, Noh TW. Pseudogap dependence of the optical conductivity spectra of Ca3Ru2O7: a possible contribution of the orbital flip excitation. Phys Rev Lett 2007; 98:097403. [PMID: 17359196 DOI: 10.1103/physrevlett.98.097403] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2006] [Indexed: 05/14/2023]
Abstract
Optical spectra of a double-layered perovskite ruthenate Ca3Ru2O7 show a pseudogap opening around 200 cm(-1) below 50 K, which is attributable to the partial k-space gap opening due to the density wave instability. Unlike most other density wave materials, Ca3Ru2O7 has spectral weight redistributions, not near the energy gap region, but at a much higher energy region around 800 cm(-1). As a possible origin of these intriguing features, we discuss the orbital flip excitation in the density wave ground state.
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Affiliation(s)
- J S Lee
- ReCOE & FPRD, Department of Physics and Astronomy, Seoul National University, Seoul 151-747, Korea
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39
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Yoon DS, Won K, Kim YH, Song BK, Kim SJ, Moon SJ, Kim BS. Continuous removal of hydrogen peroxide with immobilised catalase for wastewater reuse. Water Sci Technol 2007; 55:27-33. [PMID: 17305120 DOI: 10.2166/wst.2007.016] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Hydrogen peroxide was continuously removed for wastewater reuse using an immobilised biocatalyst. A commercial catalase, which is an enzyme to decompose hydrogen peroxide to water and oxygen, was entrapped in chitosan beads. Hydrogen peroxide in aqueous solutions of varying pH, temperature and concentration was continuously removed through a reactor containing the catalase-entrapped chitosan beads at high efficiency for 24 h. Additional silicate coating of the chitosan beads resulted in significant improvements in the catalase performance under harsh conditions, which are often found in peroxide-based industrial processes. We expect that immobilisation of catalases can enhance their applicability for continuous degradation of hydrogen peroxide for wastewater reuse.
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Affiliation(s)
- D S Yoon
- Korea Research Institute of Chemical Technology, 100 Jang-dong, Yuseong-gu, Daejeon 305-343, Korea
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40
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Kim MW, Moon SJ, Jung JH, Yu J, Parashar S, Murugavel P, Lee JH, Noh TW. Effect of orbital rotation and mixing on the optical properties of orthorhombic RMnO3 (R=La, Pr, Nd, Gd, and Tb). Phys Rev Lett 2006; 96:247205. [PMID: 16907278 DOI: 10.1103/physrevlett.96.247205] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2005] [Indexed: 05/11/2023]
Abstract
We investigated the ab-plane absorption spectra of RMnO3 (R=La, Pr, Nd, Gd, and Tb) thin films. As the ionic radius of the R ion decreases, we observed a drastic suppression of the 2 eV peak, i.e., the intersite optical transition between spin- and orbital-aligned states across the Mott gap. We found that, in addition to orbital rotation, orbital mixing in the orbital-ordered state should play an important role in the suppression of 2 eV peak. We also found that the spectral weight of 2 eV peak is proportional to the A-type antiferromagnetic ordering temperature, which suggests that the magnetic interaction should be sensitively coupled to the orbital degree of freedom.
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Affiliation(s)
- M W Kim
- ReCOE & School of Physics, Seoul National University, Seoul 151-747, Korea
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41
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Lee JS, Moon SJ, Noh TW, Nakatsuji S, Maeno Y. Orbital-selective mass enhancements in multiband Ca(2-x)Sr(x)RuO4 systems analyzed by the extended Drude model. Phys Rev Lett 2006; 96:057401. [PMID: 16486981 DOI: 10.1103/physrevlett.96.057401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2005] [Revised: 08/09/2005] [Indexed: 05/06/2023]
Abstract
We investigated optical spectra of quasi-two-dimensional multiband systems. The extended Drude model analysis on the -plane optical conductivity spectra indicates that the effective mass should be enhanced near . Based on the sum rule argument, we showed that the orbital-selective Mott-gap opening for the bands, the widely investigated picture, could not be the origin of the mass enhancement. We exploited the multiband effects in the extended Drude model analysis, and demonstrated that the intriguing heavy mass state near should come from the renormalization of the band.
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Affiliation(s)
- J S Lee
- ReCOE & School of Physics, Seoul National University, Seoul 151-747, Korea
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42
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Filevich J, Rocca JJ, Marconi MC, Moon SJ, Nilsen J, Scofield JH, Dunn J, Smith RF, Keenan R, Hunter JR, Shlyaptsev VN. Observation of a multiply ionized plasma with index of refraction greater than one. Phys Rev Lett 2005; 94:035005. [PMID: 15698278 DOI: 10.1103/physrevlett.94.035005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2004] [Indexed: 05/24/2023]
Abstract
We present clear experimental evidence showing that the contribution of bound electrons can dominate the index of refraction of laser-created plasmas at soft x-ray wavelengths. We report anomalous fringe shifts in soft x-ray laser interferograms of Al laser-created plasmas. The comparison of measured and simulated interferograms shows that this results from the dominant contribution of low charge ions to the index of refraction. This usually neglected bound electron contribution can affect the propagation of soft x-ray radiation in plasmas and the interferometric diagnostics of plasmas for many elements.
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Affiliation(s)
- J Filevich
- NSF ERC for Extreme Ultraviolet Science and Technology and Department of Electrical and Computer Engineering, Colorado State University, Fort Collins, Colorado 80523, USA
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Bradley DK, Eggert JH, Hicks DG, Celliers PM, Moon SJ, Cauble RC, Collins GW. Shock compressing diamond to a conducting fluid. Phys Rev Lett 2004; 93:195506. [PMID: 15600850 DOI: 10.1103/physrevlett.93.195506] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2004] [Indexed: 05/24/2023]
Abstract
Laser generated shock reflectance data show that diamond undergoes a continuous transition from optically absorbing to reflecting between Hugoniot pressures 600<P(H)<1000 GPa. The data are consistent with diamond having a thermal population of carriers at P(H) approximately 600 GPa, undergoing band overlap metallization at P(H) approximately 1000 GPa and melting at 800<P(H)<1000 GPa. The results agree well with an equation of state model that predicts that elemental carbon remains solid throughout the interior of Neptune.
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Affiliation(s)
- D K Bradley
- Lawrence Livermore National Laboratory, Livermore, California 94551, USA
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Hicks DG, Celliers PM, Collins GW, Eggert JH, Moon SJ. Shock-induced transformation of Al2O3 and LiF into semiconducting liquids. Phys Rev Lett 2003; 91:035502. [PMID: 12906427 DOI: 10.1103/physrevlett.91.035502] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2002] [Indexed: 05/24/2023]
Abstract
Shock compression of sapphire (Al2O3) and lithium fluoride (LiF) to pressures above 5 Mbar has been observed to transform these transparent, wide band-gap insulators into partially degenerate liquid semiconductors with optical reflectivities of several percent. Reflectivities rise steadily with shock pressure up to 45% in sapphire at 20 Mbar and 20% in LiF at 13 Mbar. Using a simple model, the electron scattering length was inferred to be approximately the interatomic distance. In addition, several equation-of-state points at these pressures were measured.
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Affiliation(s)
- D G Hicks
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
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Filevich J, Rocca JJ, Jankowska E, Hammarsten EC, Kanizay K, Marconi MC, Moon SJ, Shlyaptsev VN. Two-dimensional effects in laser-created plasmas measured with soft-x-ray laser interferometry. Phys Rev E Stat Nonlin Soft Matter Phys 2003; 67:056409. [PMID: 12786289 DOI: 10.1103/physreve.67.056409] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2002] [Indexed: 05/24/2023]
Abstract
Soft-x-ray laser interferograms of laser-created plasmas generated at moderate irradiation intensities (1 x 10(11)-7 x 10(12) W cm(-2)) with lambda=1.06 microm light pulses of approximately 13-ns-FWHM (full width at half maximum) duration and narrow focus (approximately 30 microm) reveal the unexpected formation of an inverted density profile with a density minimum on axis and distinct plasma sidelobes. Model simulations show that this strong two-dimensional hydrodynamic behavior is essentially a universal phenomena that is the result of plasma radiation induced mass ablation and cooling in the areas surrounding the focal spot.
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Affiliation(s)
- J Filevich
- Department of Electrical and Computer Engineering, Colorado State University, Fort Collins, CO 80523, USA
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46
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Cha JS, Moon SJ, Park JH. A solution of borane in tetrahydrofuran. A stereoselective reducing agent for reduction of cyclic ketones to thermodynamically more stable alcohols. J Org Chem 2001; 66:7514-5. [PMID: 11681970 DOI: 10.1021/jo010401c] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- J S Cha
- Department of Chemistry and Institute of Natural Sciences, Yeungnam University, Gyongsan 712-749, Republic of Korea.
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Suh J, Moon SJ. Artificial peptidase with an active site comprising a Cu(II) center and a proximal guanidinium ion. A carboxypeptidase A analogue. Inorg Chem 2001; 40:4890-5. [PMID: 11531436 DOI: 10.1021/ic001165b] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
An immobile artificial metallopeptidase having a well-defined active site was constructed on the backbone of cross-linked polystyrene by adjoining a guanidinium moiety to the Cu(II) complex of a tetraaza ligand. The catalyst (CABP) and intermediate polymers were characterized by elemental analysis, IR, inductively coupled plasma measurement, electron probe microanalysis, test for primary amines, binding of Cu(II) ion, and complexation of p-nitrobenzoate ion. CABP effectively catalyzed amide hydrolysis of carboxyl-containing N-acyl amino acids. The catalytic rate of CABP in the hydrolysis of unactivated amides was comparable to that of the catalytic antibody with the highest peptidase activity reported to date. It is proposed that the guanidinium moiety of CABP recognizes the carboxylate anion of the substrate whereas the Cu(II) center participates in the cleavage of the amide bond of the complexed substrate. Several characteristic features of carboxypeptidase A were reproduced by CABP: catalytic action of the metal ion, participation of guanidinium in substrate recognition, hydrolysis of small unactivated amides, and substrate selectivity toward amide bonds adjacent to a carboxylate group.
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Affiliation(s)
- J Suh
- School of Chemistry and Molecular Engineering and Center for Molecular Catalysis, Seoul National University, Seoul 151-747, Korea
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48
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Moon SJ, Shattuck MD, Swift JB. Velocity distributions and correlations in homogeneously heated granular media. Phys Rev E Stat Nonlin Soft Matter Phys 2001; 64:031303. [PMID: 11580328 DOI: 10.1103/physreve.64.031303] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2001] [Indexed: 05/23/2023]
Abstract
We compare the steady state velocity distributions from our three-dimensional inelastic hard sphere molecular dynamics simulation for homogeneously heated granular media, with the predictions of a mean field-type Enskog-Boltzmann equation for inelastic hard spheres [T. P. C. van Noije and M. H. Ernst, Granular Matter 1, 57 (1998)]. Although we find qualitative agreement for all values of density and inelasticity, the quantitative disagreement approaches approximately 40% at high inelasticity or density. By contrast the predictions of the pseudo-Maxwell molecule model [J. A. Carrillo, C. Cercignani, and I. M. Gamba, Phys. Rev. E, 62, 7700 (2000)] are both qualitatively and quantitatively different from those of our simulation. We also measure short-range and long-range velocity correlations exhibiting nonzero correlations at contact before the collision, and being consistent with a slow algebraic decay over a decade in the unit of the diameter of the particle, proportional to r(-(1+alpha)), where 0.2<alpha<0.3. The existence of these correlations implies the failure of the molecular chaos assumption and the mean field approximation, which is responsible for the quantitative disagreement of the inelastic hard sphere kinetic theory.
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Affiliation(s)
- S J Moon
- Center for Nonlinear Dynamics and Department of Physics, University of Texas, Austin, Texas 78712, USA.
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Kim DS, Kim SY, Moon SJ, Chung JH, Kim KH, Cho KH, Park KC. Ceramide inhibits cell proliferation through Akt/PKB inactivation and decreases melanin synthesis in Mel-Ab cells. Pigment Cell Res 2001; 14:110-5. [PMID: 11310790 DOI: 10.1034/j.1600-0749.2001.140206.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Ceramide is a bioactive sphingolipid that mediates a variety of cell functions. However, the effects of ceramide on cell growth and the melanogenesis of melanocytes are not known. In the present study, we investigated the actions of cell-permeable ceramide and its possible role in the signaling pathway of a spontaneously immortalized mouse melanocyte cell line, Mel-Ab. Our results show that C2-ceramide inhibits DNA synthesis in Mel-Ab cells and G361 human melanoma cells in a dose-dependent manner. Cell cycle analysis confirmed the inhibition of DNA synthesis by a reduction in the S phase. To investigate the ceramide signaling pathway, we studied whether C2-ceramide is able to influence extracellular signal-regulated kinase (ERK) and/or Akt/protein kinase B (PKB) activation. We demonstrated that phosphorylated Akt/PKB is decreased by C2-ceramide, whereas phosphorylated ERK was only slightly affected. Therefore, the C2-ceramide-induced inactivation of Akt/PKB may be closely related to the reduced cell proliferation of Mel-Ab cells. Furthermore, we assessed the effects of C2-ceramide on the pigmentation of Mel-Ab cells. The results obtained showed that the melanin content of cells was significantly reduced by C2-ceramide at concentrations in the range of 1-10 microM, and that the pigmentation-inhibiting effect of C2-ceramide is much greater than that of kojic acid at 1-100 microM. In addition, we found that the activity of tyrosinase is reduced by C2-ceramide treatment. Our results demonstrate that C2-ceramide reduces the pigmentation of Mel-Ab cells by inhibiting tyrosinase activity.
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Affiliation(s)
- D S Kim
- Department of Dermatology and Artificial Organ, Seoul National University College of Medicine, Chongno-Gu, Korea
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50
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Blackmon SM, Peng YW, Hao Y, Moon SJ, Oliveira LB, Tatebayashi M, Petters RM, Wong F. Early loss of synaptic protein PSD-95 from rod terminals of rhodopsin P347L transgenic porcine retina. Brain Res 2000; 885:53-61. [PMID: 11121529 DOI: 10.1016/s0006-8993(00)02928-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Retinitis pigmentosa (RP), a type of retinal degeneration involving first rod and then slow cone photoreceptor degeneration, can be caused by any of a number of mutations in different genes. In the cases of mutations affecting rod-specific genes such as rhodopsin, it is unclear how the mutations may cause degeneration of cones. We have used the porcine retina, which is rod-dominated and has an abundance of cones, to study the mutation-induced changes in both rod and cone photoreceptors. Like patients with the same mutation, rhodopsin P347L transgenic swine manifest rod-cone degeneration. In addition, the rod bipolar cells fail to form synaptic connections with rods; instead, they form ectopic synapses with cones. The mechanisms that prevent the formation of the rod-rod bipolar cell synaptic connection are not known. We used specific antibodies and immunocytochemistry to show that the synaptic protein, PSD-95, is present in both normal and transgenic porcine retinas. During neonatal development, however, PSD-95 is lost from rod terminals in the transgenic swine. This loss is virtually complete (90%) by postnatal day 5, at a time when greater than 80% of rod cell bodies still remain. Furthermore, the remaining rods retain their outer segments and their gross morphology appears relatively normal. In contrast, PSD-95 expression continues in cone terminals, even in 10-month-old transgenic swine, where the rods have all disappeared and the cones show signs of severe degeneration. These results suggest that loss of PSD-95 may not be a general consequence of the deteriorating cell. Rather, the very early and selective loss of PSD-95 from the rod terminals may be causally related to the absence of rod-rod bipolar cell synapses in the rhodopsin P347L transgenic retina.
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Affiliation(s)
- S M Blackmon
- Department of Ophthalmology, Duke University School of Medicine, Durham, NC 27710, USA
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