Cation segregation on perovskite oxide surfaces affects vastly the oxygen reduction activity and stability of solid oxide fuel cell (SOFC) cathodes. A unified theory that explains the physical origins of this phenomenon is therefore needed for designing cathode materials with optimal surface chemistry. We quantitatively assessed the elastic and electrostatic interactions of the dopant with the surrounding lattice as the key driving forces for segregation on model perovskite compounds, LnMnO3 (host cation Ln = La, Sm). Our approach combines surface chemical analysis with X-ray photoelectron and Auger electron spectroscopy on model dense thin films and computational analysis with density functional theory (DFT) calculations and analytical models. Elastic energy differences were systematically induced in the system by varying the radius of the selected dopants (Ca, Sr, Ba) with respect to the host cations (La, Sm) while retaining the same charge state. Electrostatic energy differences were introduced by varying the distribution of charged oxygen and cation vacancies in our models. Varying the oxygen chemical potential in our experiments induced changes in both the elastic energy and electrostatic interactions. Our results quantitatively demonstrate that the mechanism of dopant segregation on perovskite oxides includes both the elastic and electrostatic energy contributions. A smaller size mismatch between the host and dopant cations and a chemically expanded lattice were found to reduce the segregation level of the dopant and to enable more stable cathode surfaces. Ca-doped LaMnO3 was found to have the most stable surface composition with the least cation segregation among the compositions surveyed. The diffusion kinetics of the larger dopants, Ba and Sr, was found to be slower and can kinetically trap the segregation at reduced temperatures despite the larger elastic energy driving force. Lastly, scanning probe image contrast showed that the surface chemical heterogeneities made of dopant oxides upon segregation were electronically insulating. The consistency between the results obtained from experiments, DFT calculations, and analytical theory in this work provides a predictive capability to tailor the cathode surface compositions for high-performance SOFCs.

Obesity increases the risks of diabetes, hypertension, and cardiovascular diseases, ultimately contributing to mortality. Korean Society for the Study of Obesity (KSSO) was established to improve the management of obesity through research and education; to that end, the Committee of Clinical Practice Guidelines of KSSO reviews systemic evidence using expert panels to develop clinical guidelines. The clinical practice guidelines for obesity were revised in 2018 using National Health Insurance Service Health checkup data from 2006 to 2015. Following these guidelines, we added a category, class III obesity, which includes individuals with body mass index (BMI) ≥35 kg/m 2 . Agreeing with the International Federation for the Surgery of Obesity and Metabolic Disorders, Asian Pacific Chapter consensus, we determined that bariatric surgery is indicated for Korean patients with BMI ≥35 kg/m 2 and for Korean patients with BMI ≥30 kg/m 2 who have comorbidities. The new guidelines focus on guiding clinicians and patients to manage obesity more effectively. Our recommendations and treatment algorithms can serve as a guide for the evaluation, prevention, and management of overweight and obesity.

etabolic syndrome is a cluster of metabolic abnormalities related to an increased risk of cardiovascular disease, 1 and recent research has demonstrated that adipocytokines, especially adiponectin, are associated with metabolic syndrome. 2 In terms of the evaluation and management of hypercholesterolemia (a risk factor of cardiovascular disease and a causative factor of death in more than 40% of heart-related deaths) according to the recommendations of the 2001 Third Report of the National Cholesterol Education Program (NCEP) Adult Treatment Panel (ATP) III Guidelines, the risk factors for the development of metabolic syndrome are visceral obesity, hypertension, hypertriglyceridemia, a low level of high-density lipoprotein cholesterolemia, and an impaired glucose tolerance. 3 Hyperuricemia is also considered by some investigators to be a component of metabolic syndrome that reflects insulin resistance. 4,5 In several epidemiological studies, a close relationship between hyperuricemia and hypertension, heart failure and other cardiovascular diseases has been reported, [6][7][8][9] and correlations between hyperuricemia and obesity, dyslipidemia, and diabetes have also been recently reported. [10][11][12] However, studies of Asians, who differ physically from Caucasians, are relatively rare. In Korea, knowledge of the general adult population without type 2 diabetes, hypertension and other diseases is inadequate, and no study has been performed on the association between the newly defined metabolic syndrome and hyperuricemia in the Korean population. Hence, this study investigated Korean adults who had undergone health screening to assess the correlation between increased serum uric acid concentration and hypertension, insulin resistance, and other risk factors of metabolic syndrome. Methods Study PopulationThe study group comprised 53,477 individuals (34,169 males, 19,308 females), who underwent health screening at Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Korea between January 1, 2002, and December 31, 2002. Subjects who were taking diuretics, antihypertensive or antidiabetic agents, lipid-lowering agents, hyper-or hypouricemic agents, and those with any clinical suspicion of malignancy, acute infectious disease, acute inflammatory disease or renal disease were excluded. Physical Examination and Blood Pressure (BP)Height, weight, waist -hip circumference and systolic and diastolic BP were measured. According to the Hypertension Detection and Follow-up Program protocol, 13 BP was measured using a sphygmomanometer after the subjects had rested for more than 5 min. For those with a systolic BP >140 mmHg and a diastolic BP >90 mmHg (defined as hypertension by the 2003 JNC-7 14 ) BP was measured on a further 2 occasions after resting, and average Seung Ho Ryu, MD*; Dong Geuk Keum, MD** Background Associations between hyperuricemia, cardiovascular diseases and diabetes have been reported, but few of the studies have been conducted in the Korean population. The present study examined ...

It has been suggested that oxidative stress is associated with the pathogenesis of osteoporosis. The objective of this study was to explore the association between a marker of oxidative stress and either bone turnover markers or bone mineral density (BMD) in postmenopausal women. In addition, the effects of oxidative stress on the formation of osteoclasts in human bone marrow cell culture were examined. We performed a cross-sectional analysis in healthy postmenopausal women aged 60-78 years (n = 135, 68.2 +/- 4.9). Oxidative stress was evaluated in the serum by measuring 8-hydroxy-2'-deoxyguanosine (8-OH-dG) levels. The biochemical markers of bone turnover and areal BMD were measured in all participants. Multivariate linear regression analysis revealed a negative association between 8-OH-dG levels and BMD of the lumbar spine, total hip, femoral neck, and trochanter and positive association with type I collagen C-telopeptide (ICTP) levels. The odds ratio of 8-OH-dG for osteoporosis was 1.54 (1.14-2.31, P = 0.003). In cultures of primary human marrow cells, H2O2 caused concentration-dependent activation of TRAP-positive multinucleated giant cells. H2O2 also increased the area of pits per osteoclast activity assay substrate. RT-PCR showed that H2O2 stimulated the expression of M-CSF and RANKL and increased the RANKL/OPG ratio. The data support the view that oxidative stress is associated with increased bone resorption and low bone mass in otherwise healthy women. In addition, RANKL and M-CSF stimulation induced by oxidative stress may participate in osteoclastogenesis in human bone.

The dramatic increase in the prevalence of obesity and its accompanying comorbidities are major health concerns in Korea. Obesity is defined as a body mass index ≥25 kg/m2 in Korea. Current estimates are that 32.8% of adults are obese: 36.1% of men and 29.7% of women. The prevalence of being overweight and obese in national surveys is increasing steadily. Early detection and the proper management of obesity are urgently needed. Weight loss of 5% to 10% is the standard goal. In obese patients, control of cardiovascular risk factors deserves the same emphasis as weight-loss therapy. Since obesity is multifactorial, proper care of obesity requires a coordinated multidisciplinary treatment team, as a single intervention is unlikely to modify the incidence or natural history of obesity.

Techniques for anionic defect engineering in transition metal oxides and mechanisms of how anion defects affect their oxygen reaction activities.

Insulin resistance and systemic inflammatory response are of key importance for inducing NAFLD, particularly in apparently healthy non-obese men.

The effects of exendin-4 on Sirt1 expression as a mechanism of reducing fatty liver have not been previously reported. Therefore, we investigated whether the beneficial effects of exendin-4 treatment on fatty liver are mediated via Sirt1 in high-fat (HF) diet-induced obese C57BL/6J mice and related cell culture models. Exendin-4 treatment decreased body weight, serum free fatty acid (FA), and triglyceride levels in HF-induced obese C57BL/6J mice. Histological analysis showed that exendin-4 reversed HF-induced hepatic accumulation of lipids and inflammation. Exendin-4 treatment increased mRNA and protein expression of Sirt1 and its downstream factor, AMPK, in vivo and also induced genes associated with FA oxidation and glucose metabolism. In addition, a significant increase in the hepatic expression of Lkb1 and Nampt mRNA was observed in exendin-4-treated groups. We also observed increased expression of phospho-Foxo1 and GLUT2, which are involved in hepatic glucose metabolism. In HepG2 and Huh7 cells, mRNA and protein expressions of GLP-1R were increased by exendin-4 treatment in a dose-dependent manner. Exendin-4 enhanced protein expression of Sirt1 and phospho-AMPKα in HepG2 cells treated with 0.4 mM palmitic acid. We also found that Sirt1 was an upstream regulator of AMPK in hepatocytes. A novel finding of this study was the observation that expression of GLP-1R is proportional to exendin-4 concentration and exendin-4 could attenuate fatty liver through activation of Sirt1.