Redesign of Anode Catalyst for Sustainable Survival of Fuel Cells.

Polymer electrolyte membrane fuel cells (PEMFCs) suffer from severe performance degradation when operating under harsh conditions such as fuel starvation, shut-down/start-up, and open circuit voltage. A fundamental solution to these technical issues requires an integrated approach rather than condition-specific solutions. In this study, an anode catalyst based on Pt nanoparticles encapsulated in a multifunctional carbon layer (MCL), acting as a molecular sieve layer and protective layer is designed. The MCL enabled selective hydrogen oxidation reaction on the surface of the Pt nanoparticles while preventing their dissolution and agglomeration. Thus, the structural deterioration of a membrane electrode assembly can be effectively suppressed under various harsh operating conditions. The results demonstrated that redesigning the anode catalyst structure can serve as a promising strategy to maximize the service life of the current PEMFC system.

Origin and Formation Mechanism of Carbon Shell-Encapsulated Metal Nanoparticles for Powerful Fuel Cell Durability.

Proton exchange membrane fuel cells (PEMFCs) face technical issues of performance degradation due to catalyst dissolution and agglomeration in real-world operations. To address these challenges, intensive research has been recently conducted to introduce additional structural units on the catalyst surface. Among various concepts for surface modification, carbon shell encapsulation is known to be a promising strategy since the carbon shell can act as a protective layer for metal nanoparticles. As an interesting approach to form carbon shells on catalyst surfaces, the precursor ligand-induced formation is preferred due to its facile synthesis and tunable control over the carbon shell porosity. However, the origin of the carbon source and the carbon shell formation mechanism have not been studied in depth yet. Herein, this study aims to investigate carbon sources through the use of different precursors and the introduction of new methodologies related to the ligand exchange phenomenon. Subsequently, we provide new insights into the carbon shell formation mechanism using X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). Finally, the thermal stability and electrochemical durability of carbon shells are thoroughly investigated through in situ transmission electron microscopy (in situ TEM) and accelerated durability tests.

Fine-tuning of ultrathin carbon shells coated on metal nanoparticles: carbon etching and defect healing effects.

Carbon-incorporated metal nanoparticles are heat-treated in various gas atmospheres to create carbon shells with different porosity. A highly porous carbon shell is formed due to the carbon etching effect by H2, and the defect healing effect by CO is discovered through additional CO gas treatment of the H2/N2 gas-treated sample.

Activity Quantification of Fuel Cell Catalysts via Sequential Poisoning by Multiple Reaction Inhibitors.

The development of non-Pt or carbon-based catalysts for anion exchange membrane fuel cells (AEMFCs) requires identification of the active sites of the catalyst. Since not only metals but also carbon materials exhibit oxygen reduction reaction (ORR) activity in alkaline conditions, the contribution of carbon-based materials to ORR performance should also be thoroughly analyzed. However, the conventional CN- poisoning experiments, which are mainly used to explain the main active site of M-N-C catalysts, are limited to only qualitative discussions, having the potential to make fundamental errors. Here, we report a modified electrochemical analysis to quantitatively investigate the contribution of the metal and carbon active sites to ORR currents at a fixed potential by sequentially performing chronoamperometry with two reaction inhibitors, CN- and benzyl trimethylammonium (BTMA+). As a result, we discover how to quantify the individual contributions of two active sites (Pt nanoparticles and carbon support) of carbon-supported Pt (Pt/C) nanoparticles as a model catalyst. This study is expected to provide important clues for the active site analysis of carbon-supported non-Pt catalysts, such as M-N-C catalysts composed of heterogeneous elements.

Regulation of BRCA1 stability through the tandem UBX domains of isoleucyl-tRNA synthetase 1.

Aminoacyl-tRNA synthetases (ARSs) have evolved to acquire various additional domains. These domains allow ARSs to communicate with other cellular proteins in order to promote non-translational functions. Vertebrate cytoplasmic isoleucyl-tRNA synthetases (IARS1s) have an uncharacterized unique domain, UNE-I. Here, we present the crystal structure of the chicken IARS1 UNE-I complexed with glutamyl-tRNA synthetase 1 (EARS1). UNE-I consists of tandem ubiquitin regulatory X (UBX) domains that interact with a distinct hairpin loop on EARS1 and protect its neighboring proteins in the multi-synthetase complex from degradation. Phosphomimetic mutation of the two serine residues in the hairpin loop releases IARS1 from the complex. IARS1 interacts with BRCA1 in the nucleus, regulates its stability by inhibiting ubiquitylation via the UBX domains, and controls DNA repair function.

A comprehensive examination of association between belief in vaccine misinformation and vaccination intention in the COVID-19 context.

Misinformation about COVID-19 vaccines is widely available in the public communication environment. Exposure to the misinformation may increase perceived risk of and evoke negative emotions toward COVID-19 vaccines that may eventually reduce COVID-19 vaccination intentions. The negative influences of misinformation may vary by aspects of individuals' social networks. Expanding the reasoned action approach, we proposed a comprehensive model to examine the roles of misinformation beliefs, perceived risk, fear, worry, and social networks in explaining COVID-19 vaccination intentions. We tested the model using survey data of South Korean adults, collected when the Korean government launched its nationwide vaccination program in April 2021 (n = 744). The results from our step-by-step path analyses indicated that COVID-19 vaccination intentions had positive direct associations with vaccination-specific factors such as attitudes toward, injunctive norms on, and perceived behavioral control over COVID-19 vaccination. Perceived risk was also directly linked to intentions. Among these factors, attitudes and injunctive norms were most strongly related to intentions. Misinformation beliefs and worry had negative indirect relationships with intentions via the mediation of these variables directly connected to intentions. The negative influences of misinformation beliefs were greater among respondents reported stronger tie strengths. Theoretical and practical implications were discussed.

Eco-friendly alkaline lignin/cellulose nanofiber drying system for efficient redispersion behavior.

Although nanocellulose is an eco-friendly, high-performance raw material provided by nature, the agglomeration of nanocellulose that occurs during the drying process is the biggest obstacle to its advanced materialization and commercialization. In this study, a facile and simple nanocellulose drying system was designed using lignin, which is self-assembled together with cellulose in natural wood, as an eco-friendly additive. The addition of lignin not only minimized aggregation during the drying and dehydration process of nanocellulose but also ensured excellent redispersion kinetics and stability. In addition, the added lignin could be removed through a simple washing process. Through FTIR, XRD, TGA, tensile and swelling tests, it was confirmed that the addition of lignin enabled the reversible restitution of the nanocellulose physicochemical properties to the level of pristine never-dried nanocellulose in drying, redispersion, and polymer processing processes.

Cationic surface-modified regenerated nanocellulose hydrogel for efficient Cr(VI) remediation.

Because nanocellulose has a large specific surface area and abundant hydroxyl functional groups due to its unique nanomorphology, interest increases as an eco-friendly water treatment material. However, the distinctive properties of nanocellulose, which exists in a dispersion state, strongly hamper its usage in practical water treatment processes. Additionally, nanocellulose shows low performance in removing anionic pollutants because of its anionic characteristics. In an effort to address this challenge, regenerated cellulose (RC) hydrogel was fabricated through cellulose's dissolution and regeneration process using an eco-friendly aqueous solvent system. Subsequently, a crosslinking process was carried out to introduce the cationic functional groups to the RC surface PEI coating (P/RC). As a result, the PEI surface cationization process improved the mechanical rigidity of RC and showed an excellent Cr(VI) removal capacity of 578 mg/g. In addition, the prepared P/RC maintained more than 90% removal efficiency even after seven reuses.

Highly efficient Cr(VI) remediation by cationic functionalized nanocellulose beads.

Applications of nanocellulose as a water treatment material are being actively pursued based on its interesting properties, such as renewability, large specific surface area, hydrophilic surface chemistry, and biodegradability. This study used carboxymethyl cellulose nanofibrils (CMCNFs) to prepare a typical bead-type adsorbent with improved structural stability as an actual water treatment restoration material. In addition, a cationized nanocellulose adsorbent was prepared by introducing polyethyleneimine (PEI) on the surface of the CMCNF (P/CMCNF), the removal efficiency of Cr(VI) was evaluated, and its mechanism was elucidated. As a result, the P/CMCNF beads showed an excellent Cr(VI) removal capacity of 1302.3 mg/g, the best result among cellulose-based adsorption materials. Cr(VI) was effectively removed by electrostatic attractions combined with chemical reduction and chelation mechanisms. Furthermore, the macrobead fabrication and PEI surface modification process improved the underwater stability of the P/CMCNF, and it showed excellent reuse efficiency.

Association between Irritable Bowel Syndrome and Risk of Osteoporosis in Korean Premenopausal Women.

OBJECTIVE: The objective of this study is to evaluate irritable bowel syndrome (IBS) as a risk factor for osteoporosis and osteoporotic fracture in Korean women after controlling for basic confounding factors and considering detailed demographic and clinical information. SUBJECTS AND METHODS: We performed a nationwide population-based retrospective cohort analysis and matched every IBS case with a non-IBS case at a 1:4 frequency ratio based on age. The population consisted of female patients with data in the Health Insurance Review and Assessment (HIRA) database from 2002 to 2010. To determine the risk of osteoporosis and osteoporotic fracture in IBS and non-IBS patients, hazard ratios (HRs) with 95% confidence intervals (CI) were estimated using Cox proportional hazards regression models, adjusting for confounding variables, such as the area of residence, health insurance type, and economic status. RESULTS: We identified 1,017,468 patients in the HIRA database with data from 2002 to 2010 who could potentially be included in the cohort. Among these, we identified 1,545 (11.4%) women (age >19 years) with newly diagnosed IBS (IBS group). Additionally, 6,180 patients without IBS and age-matched to the IBS group were selected. Cox modeling revealed that the crude HRs for osteoporosis and osteoporotic fractures in patients with IBS were 1.476 (95% CI, 1.241-1.754) and 1.427 (95% CI, 1.086-1.876), respectively. CONCLUSION: Our data showed an increased incidence of osteoporosis and osteoporotic fractures in women with IBS compared with age-matched controls.

Effects of education methods on self-efficacy of smoking cessation counseling among medical students.

BACKGROUND: Medical students need to receive training in providing smoking cessation counseling to provide effective smoking cessation interventions to smokers when they become doctors. This study examined the smoking cessation education curricula and factors affecting counseling self-efficacy (CSE) in smoking cessation treatment among medical students. METHODS: In a multicenter cross-sectional study, we obtained demographic information, personal history of tobacco use and intention to quit smoking, exposure to secondhand smoke in the school premises during the past week, the experience of learning about tobacco in each medical school, tobacco-related medical knowledge, and self-efficacy in smoking cessation counseling on medical students of four Korean medical schools. RESULTS: Among 1,416 medical students eligible, 313 (22.1%) students completed a self-administered questionnaire. Only 20.3% of the students reported positive CSE on smoking cessation. The factors affecting positive CSE were scores of ≥ 60 on tobacco-related medical knowledge, smoking experience, and blended learning (p = 0.014, 0.005, and 0.015, respectively). CONCLUSION: This study shows that high scores in tobacco-related medical knowledge and blended learning are correlated with positive CSE for smoking cessation counseling.

Effects of Sleep Patterns on the Subjective Health Status in Older Men from the 7th Korea National Health and Nutrition Examination Survey, 2016.

BACKGROUND: Sleeping is a major component of health. The prevalence of sleep disorders is expected to be high in older adults, and sleep habits generally differ on weekdays and weekends. This study aimed to clarify the associations between sleep habits and the subjective health status of older adults. METHODS: This study analyzed data of 1,678 older adults (695 men and 883 women) aged 65 years or older who had participated in the 2016 Korea National Health and Nutrition Examination Survey (KNHANES VII-1) conducted by the Korea Centers for Disease Control and Prevention. The participants' subjective health perceptions were analyzed according to their sleep habits. RESULTS: Weekday and weekend sleep durations were related to subjective health in older men (p<0.05) but not in women. The subjective health perception was significantly better for a 9-hour sleep duration than for a 7-hour sleep duration in older men. Sleeping and waking times on weekdays and weekends were not related to the subjective health of either men or women. CONCLUSION: Weekday and weekend sleep durations were related to subjective health perception in older men.

The Application of Auriculotherapy to the Treatment of Chronic Spontaneous Urticaria: A Systematic Review and Meta-analysis.

Auriculotherapy has been extensively used for chronic spontaneous urticaria in China. However, the evidence of its effectiveness and safety for the treatment of chronic spontaneous urticaria is insufficient. Hence, we conducted this study to compare auriculotherapy or auriculotherapy joint treatment with Western medicine for the cure of chronic spontaneous urticaria. This meta-analysis of seven randomized controlled trials showed that auriculotherapy or auriculotherapy joint treatment was significantly superior to Western medicine in curing clinical signs and symptoms of chronic spontaneous urticaria [odds ration (OR), 2.61; 95% confidence interval (CI), 1.54-4.43; p = 0.0004) and also better in total effect rate (OR, 3.81; 95% CI, 2.07-7.01; p＜0.0001). But, auriculotherapy or auriculotherapy joint treatment was similar to Western medicine in improving clinical signs and symptoms of chronic spontaneous urticaria (OR, 0.74; 95% CI, 0.35-1.56; p = 0.42). Auriculotherapy or auriculotherapy joint treatment was safer than Western medicine for curing chronic spontaneous urticaria (OR, 0.26; 95% CI, 0.09-0.80; p = 0.02). Auriculotherapy alone or auriculotherapy joint treatment appears to be more effective and safer than Western medicine that contains antihistamines in the treatment of chronic spontaneous urticaria. However, these findings should be interpreted with caution due to the unclear risk bias of methodological quality, and further studies with large-scale, better, and more rigorously designed protocol are necessary to prove these findings.

Health behaviors of Korean adults with hepatitis B: Findings of the 2016 Korean National Health and Nutrition Examination Survey.

AIM: To assess the frequencies of five health-related behaviors (smoking, alcohol consumption, body weight, sleep duration, and physical activity) in Korean adults with chronic hepatitis B. METHODS: Data were obtained from the 2016 Korean National Health and Nutrition Examination Survey. In total, 5887 subjects (2568 males, 3319 females) over 19 years old were enrolled in this study. Interviews were performed to obtain information on demographic characteristics and medical conditions. A selfadministered questionnaire and medical examination were used to assess the smoking history, alcohol use, physical activity, sleep duration, and body weight of the subjects. Chronic hepatitis B was diagnosed based on detection of hepatitis B surface antigen (HBsAg). The subjects were categorized into HBsAg positive and negative groups, and a complex sampling analysis was conducted to compare the health behaviors between these groups. RESULTS: Among males, the current smoking rate in the HBsAg positive group was higher than that in the negative group (45.5% vs 38.5%). In the positive group, the rates of monthly and high-risk alcohol use were 70.4% and 17.6% in males and 45.9% and 3.8% in females, respectively. The rate of alcohol use was similar between the two groups [P = 0.455 (males) and P = 0.476 (females)]. In the HBsAg positive group, 32.3% and 49.9% of males and 26.5% and 49.6% of females were overweight and physically inactive, respectively. High-risk alcohol consumption and physical inactivity were significantly associated with self-perceived health status. CONCLUSION: Our data demonstrate that a large proportion of Korean adults with chronic hepatitis B have poor health behaviors. Further studies are needed to confirm our results.

Clustering Effects of Metabolic Factors and the Risk of Metabolic Syndrome.

BACKGROUND: Metabolic syndrome is a major risk factor for cardiovascular disease. Clustering of a combination of individual factors that increase the actual rather than the expected prevalence might be helpful in understanding the pathophysiology of metabolic syndrome. The aim of this study was to analyze the most influential factors for metabolic syndrome to assess clustering factors of metabolic syndrome. METHODS: Subjects from the Korea National Health and Nutrition Examination Survey (KNHANES) VI were included in the present study. The status of health behaviors was obtained using the questionnaires included in the KNHANES VI. A complex, stratified, and multistage sampling design was used to analyze the data according to statistics from the Korea Centers for Disease Control and Prevention. RESULTS: A total of 2,101 men and 2,831 women aged older than 20 years were included in this study. In men, drinking alcohol more than twice per week was related with the prevalence of metabolic syndrome; while, in women, exercise was related with the prevalence of metabolic syndrome. The clustering effect was observed for more than three metabolic factors. In men, the clustering effect was strongest for the combination of hypertension, hyperglycemia, and hypertriglyceridemia. In women, the strongest clustering effect was observed for the combination of abdominal obesity, hypertriglyceridemia, and low high-density lipoprotein cholesterol concentration. CONCLUSION: The health behaviors affecting metabolic syndrome in men and women included drinking alcohol more than twice a week and exercising more than four times a week, respectively; in addition, hypertriglyceridemia most significantly influenced the clustering effect of metabolic syndrome.

Association Between Serum 25-Hydroxyvitamin D Levels and Dry Eye in Korean Adults: A Study Based on Korean National Health and Nutrition Examination Survey, 2010-2011.

BACKGROUND: Dry eye is a common disease. Many patients continue to experience residual symptoms despite optimal treatment. Thus, new treatment options are required. The purpose of this study was to evaluate the association between serum 25-hydroxyvitamin D [25(OH)D] levels and dry eye. METHODS: This study was performed using data from the fifth Korean National Health and Nutrition Examination Survey, which is a cross-sectional study of the Korean population that was conducted from 2010 to 2011. We included adults aged >19 years who underwent ophthalmologic interviews and examinations. We excluded subjects who had comorbid conditions (rheumatoid arthritis, thyroid disease, chronic kidney disease, or depression) that are associated with dry eye. The subjects were divided into normal and dry eye groups. The dry eye group consisted of those who had clinically diagnosed dry eye syndrome or symptoms. Multiple logistic regression analysis was conducted to determine the association between serum 25(OH)D levels and dry eye. RESULTS: In the univariate model, the 25(OH)D levels were lower in the dry eye group than in the normal group (P=0.01). A significant association was found between severe vitamin D deficiency (<10 ng/mL) and dry eye (P=0.04). However, after multivariate adjustment, the statistical significance of the association disappeared (P-values= 0.49, vitamin D insufficiency; P=0.33, vitamin D deficiency; P=0.18, severe vitamin D deficiency). CONCLUSION: Severe vitamin D deficiency was associated with dry eye in an unadjusted model, but the association was not statistically significant after adjustment.

The relationship between hypertension and sleep duration: an analysis of the fifth Korea National Health and Nutrition Examination Survey (KNHANES V-3).

INTRODUCTION: Hypertension is a significant risk factor for cardiovascular disease (CVD). The majority of patients, however, cannot easily maintain a healthy blood pressure. Therefore, lifestyle modifications are important and may include getting enough sleep. The purpose of this study was to determine the relationship between sleep duration and hypertension, as defined by the Joint National Committee (JNC) 7 and JNC 8 guidelines. METHODS: We used the data from 6,365 individuals aged ≥ 18 years based on national data from a representative sample of the 5(th) Korea National Health and Nutrition Examination Survey V-3 in 2012. The participants were divided into three categories: JNC 7, JNC 8, and newly excluded only. The duration of sleep was classified as less than 5, 6, 7, 8, or more than 9 hours. RESULTS: Compared with the appropriate sleep duration of 7 hours, with a sleep duration of less than 5 hours, the recommended pharmacological treatment of hypertension rate increased 1.908-fold (95% CI = 1.483-2.456) according to the JNC 8 guidelines and 1.864-fold (95% CI = 1.446-2.403) according to the JNC 7 guidelines. However, there was no statistical difference with the other sleep categories. DISCUSSION: The recommended hypertension treatment rate increased significantly in the less than 5 hours sleep group according to the JNC 8 guidelines. To manage hypertension effectively, it may be useful to maintain a lifestyle of sleeping more than 6 hours.

The association between 25-hydroxyvitamin D and mammographic density in healthy pre- and postmenopausal women regardless of the menstrual cycle phase: a cross-sectional study.

Vitamin D deficiency is a known risk factor of breast cancer. An association between vitamin D and breast density has been suggested; however, it remains controversial. The aim of this study was to determine the association between serum 25-hydroxyvitamin D [25(OH)D] level and mammographic density. Subjects in our study included 517 patients who visited the health promotion center of the University Hospital. Mammographic density was classified using the American College of Radiology, Breast Imaging Reporting and Data System. Analysis of variance was performed to clarify the association of serum 25(OH)D level and mammographic density, and odds ratio was calculated by ordinal logistic regression analysis. The mean serum 25(OH)D level was 14.3 ± 7.0 ng/mL in all subjects. In correlation analysis, weak negative correlation was observed between serum 25(OH)D level and mammographic density groups (r = -0.09, P = 0.049). However, ordinal logistic regression analysis showed no statistically significant association between serum 25(OH)D level and mammographic density (odds ratio: 0.75, 95% confidence interval: 0.50-1.13). Results of our study showed that there is no significant association between serum 25(OH)D level and mammographic density. It is thought to be an another mechanism of serum 25(OH)D level on breast cancer risk in addition to breast density.

Association between viral hepatitis B infection and halitosis.

OBJECTIVE: Oral malodor can be increased in breath of liver patients. However, no study has been performed for the association between volatile sulfur compounds (VSCs) and viral hepatitis. The aim of the present study was to determine the relationship between viral hepatitis and VSCs. METHODS: This study analyzed 182 subjects and measured hydrogen sulfide (H2S), methyl mercaptan (CH3SH) and dimethyl sulfide [(CH3)2S] using the OralChroma(®). Hepatitis type B was evaluated. Periodontal health was assessed using the Community Periodontal Index (CPI) and bleeding on probing (BOP). Tongue coating score (TCS) was evaluated. Multiple logistic regression analyses were conducted to evaluate the relationship. RESULTS: Viral hepatitis had an elevated odds of dimethyl sulfide defined halitosis (OR = 9.22, 95% CI = 2.08-40.95) after controlling for age, gender, alcohol consumption, current smoking, periodontitis, BOP, TCS and tongue brushing habit. The magnitude of the association between viral hepatitis and VSCs defined halitosis attenuated with adjustment of mediators (alcohol consumption, periodontitis, BOP, TCS and tongue brushing habit for hydrogen sulfide defined halitosis; periodontitis, TCS and tongue brushing habit for methyl mercaptan defined halitosis; tongue brushing habit for dimethyl sulfide defined halitosis). CONCLUSIONS: Findings of this study suggest that viral hepatitis may be associated with methyl mercaptan defined halitosis.

A case of incidentally discovered subclinical cushing syndrome in a patient with chronic fatigue and anxiety.

Subclinical Cushing syndrome (SCS) is a hypothalamic-pituitary-adrenal axis abnormality characterized by autonomous cortisol secretion in patients with no typical signs or symptoms of Cushing syndrome. SCS patients may have adverse metabolic and cardiovascular effects due to slight, but continuous glucocorticoid secretion. Glucocorticoids also affect behavior, mood, neural activity, and a number of specific biochemical processes in the central nervous system. Here, we report a case of SCS due to an adrenal incidentaloma in a hypertensive diabetic patient who presented with chronic fatigue and anxiety that disappeared after the removal of the adrenal adenoma.