Cobalt-Doped Ceria Sensitizer Effects on Metal Oxide Nanofibers: Heightened Surface Reactivity for High-Performing Chemiresistive Sensors.

Chemiresistive gas sensors based on semiconducting metal oxides typically rely on noble metal catalysts to enhance their sensitivity and selectivity. However, noble metal catalysts have several drawbacks for practical utilization, including their high cost, their propensity for spontaneous agglomeration, and poisoning effects with certain types of gases. As such, in the interest of commercializing the chemiresistive gas sensor technology, we propose an alternative design for a noble-metal-free sensing material through the case study of Co-doped ceria (Co-CeO2) catalysts embedded in a SnO2 matrix. In this investigation, we utilized electrospinning and subsequent calcination to prepare Co-CeO2 catalyst nanoparticles integrated with SnO2 nanofibers (NFs) with uniform particle distribution and particle size regulation down to the sub-2 nm regime. The resulting Co-CeO2@SnO2 NFs exhibited superior gas sensing characteristics toward isoprene (C5H8) gas, a significant biomarker for monitoring the onset of various diseases through breath diagnostics. In particular, we identified that the Co-CeO2 catalysts, owing to the transition metal doping, facilitated the spillover of chemisorbed oxygen species to the SnO2 sensing body. This resulting in the sensor having a 27.4-fold higher response toward 5 ppm of C5H8 (compared to pristine SnO2), exceptionally high selectivity, and a low detection limit of 100 ppb. The sensor also exhibited high stability for prolonged response-recovery cycles, attesting to the strong anchoring of Co-CeO2 catalysts in the SnO2 matrix. Based on our findings, the transition metal-doped metal oxide catalysts, such as Co-CeO2, demonstrate strong potential to completely replace noble metal catalysts, thereby advancing the development of the commercially viable chemiresistive gas sensors free from noble metals, capable of detecting target gases at sub-ppm levels.

A comparative analysis on the publicness of medical services in public health institutions: With an empirical analysis of the national health insurance database.

The purpose of this study is to analyze the publicness of medical services in public and private medical institutions, with a focus on treatment performance using National Health Insurance data. Data from the National Health Insurance Service were used to compare the publicness of medical services in public and private medical institutions. Beta regression analysis was conducted after adjusting for the relevant characteristics to identify the impact on the public treatment performance of medical institutions. The public case rate of public health institutions was higher than that of private medical institutions. According to the type of medical care institution, the public case rate was higher in general hospitals and tertiary hospitals than in hospitals. Recently, it has often highlighted that increasing emphasis of profitability in the evaluation of public health institutions is damaging the publicness of medical services. Even in this study, it can be evaluated that the public case rate of public health institutions is not higher than that of private medical institutions.

Two-Dimensional Electrically Conductive Metal-Organic Frameworks as Chemiresistive Sensors.

Metal-organic frameworks (MOFs) have emerged as attractive chemical sensing materials due to their exceptionally high porosity and chemical diversity. Nevertheless, the utilization of MOFs in chemiresistive type sensors has been hindered by their inherent limitation in electrical conductivity. The recent emergence of two-dimensional conductive MOFs (2D c-MOFs) has addressed this limitation by offering enhanced electrical conductivity, while still retaining the advantageous properties of MOFs. In particular, c-MOFs have shown promising advantages for the fabrication of sensors capable of operating at room temperature. Thus, active research on gas sensors utilizing c-MOFs is currently underway, focusing on enhancing sensitivity and selectivity. To comprehend the potential of MOFs as chemiresistive sensors for future applications, it is crucial to understand not only the fundamental properties of conductive MOFs but also the state-of-the-art works that contribute to improving their performance. This comprehensive review delves into the distinctive characteristics of 2D c-MOFs as a new class of chemiresistors, providing in-depth insights into their unique sensing properties. Furthermore, we discuss the proposed sensing mechanisms associated with 2D c-MOFs and provide a concise summary of the strategies employed to enhance the sensing performance of 2D c-MOFs. These strategies encompass a range of approaches, including the design of metal nodes and linkers, morphology control, and the synergistic use of composite materials. In addition, the review thoroughly explores the prospects of 2D c-MOFs as chemiresistors and elucidates their remarkable potential for further advancements. The insights presented in this review shed light on future directions and offer valuable opportunities in the chemical sensing research field.

Exploring Optimal Water Splitting Bifunctional Alloy Catalyst by Pareto Active Learning.

Design of bifunctional multimetallic alloy catalysts, which are one of the most promising candidates for water splitting, is a significant issue for the efficient production of renewable energy. Owing to large dimensions of the components and composition of multimetallic alloys, as well as the trade-off behavior in terms of the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) overpotentials for bifunctional catalysts, it is difficult to search for high-performance bifunctional catalysts with multimetallic alloys using conventional trial-and-error experiments. Here, an optimal bifunctional catalyst for water splitting is obtained by combining Pareto active learning and experiments, where 110 experimental data points out of 77946 possible points lead to effective model development. The as-obtained bifunctional catalysts for HER and OER exhibit high performance, which is revealed by model development using Pareto active learning; among the catalysts, an optimal catalyst (Pt0.15 Pd0.30 Ru0.30 Cu0.25 ) exhibits a water splitting behavior of 1.56 V at a current density of 10 mA cm-2 . This study opens avenues for the efficient exploration of multimetallic alloys, which can be applied in multifunctional catalysts as well as in other applications.

Facile Synthesis of Co3O4/CoMoO4 Heterostructure Nanosheets for Enhanced Acetone Detection.

Although p-type semiconductors exhibit highly selective and stable chemiresistive gas sensing performances compared to conventional n-type semiconductors, their low sensitivity had long impeded their practical development. In this work, we developed highly porous Co3O4/CoMoO4 heterostructure nanosheets (NSs) with enhanced sensitivity and superior stability toward acetone gas through a facile solution-based approach with Mo-impregnated Co-based metal-organic frameworks as the starting material. The spontaneous formation of a large number of p-p heterojunctions at the Co3O4-CoMoO4 interface would facilitate the adsorption of oxygen and acetone molecules, as verified by density functional theory calculations. Consequently, experimental results showed that the Co3O4/CoMoO4 NSs have a greatly enhanced response of 8.5 toward 5 ppm acetone, which is 7.1 times higher than that of pure Co3O4 NS, without involving any noble metal catalysts. Moreover, the limit of detection of the Co3O4/CoMoO4 NSs was as low as 10 ppb. Altogether, we propose that our synthetic approach for the engineering of p-p heterojunctions is an effective strategy for the future development of highly practical and sensitive gas sensors based on p-type semiconductors.

Ultrafast Ambient-Air Exsolution on Metal Oxide via Momentary Photothermal Effect.

The process of exsolution for the synthesis of strongly anchored metal nanoparticles (NPs) on host oxide lattices has been proposed as a promising strategy for designing robust catalyst-support composite systems. However, because conventional exsolution processes occur in harsh reducing environments at high temperatures for long periods of time, the choice of support materials and dopant metals are limited to those with inherently high thermal and chemical stability. Herein, we report the exsolution of a series of noble metal catalysts (Pt, Rh, and Ir) from metal oxide nanofibers (WO3 NFs) supports in an entirely ambient environment induced by intense pulsed light (IPL)-derived momentary photothermal treatment (>1000 °C). Since the exsolution process spans an extremely short period of time (<20 ms), unwanted structural artifacts such as decreased surface area and phase transition of the support materials are effectively suppressed. At the same time, exsolved NPs (<5 nm) with uniform size distributions could successfully be formed. To prove the practical utility of exsolved catalytic NPs functionalized on WO3 NFs, the chemiresistive gas sensing characteristics of exsolved Pt-decorated WO3 NFs were analyzed, exhibiting high durability (>200 cyclic exposures), enhanced response (Rair/Rgas > 800 @ 1 ppm/350 °C), and selectivity toward H2S target gas. Altogether, we successfully demonstrated that ultrafast exsolution within a few milliseconds could be induced in ambient conditions using the IPL-derived momentary photothermal treatment and contributed to expanding the practical viability of the exsolution-based synthetic approaches for the production of highly stable catalyst systems.

Searching for an Optimal Multi-Metallic Alloy Catalyst by Active Learning Combined with Experiments.

Searching for an optimal component and composition of multi-metallic alloy catalysts, comprising two or more elements, is one of the key issues in catalysis research. Due to the exhaustive data requirement of conventional machine-learning (ML) models and the high cost of experimental trials, current approaches rely mainly on the combination of density functional theory and ML techniques. In this study, a significant step is taken toward overcoming limitations by the interplay of experiment and active learning to effectively search for an optimal component and composition of multi-metallic alloy catalysts. The active-learning model is iteratively updated using by examining electrocatalytic performance of fabricated solid-solution nanoparticles for the hydrogen evolution reaction (HER). An optimal metal precursor composition of Pt0.65 Ru0.30 Ni0.05 exhibits an HER overpotential of 54.2 mV, which is superior to that of the pure Pt catalyst. This result indicates the successful construction of the model by only utilizing the precursor mixture composition as input data, thereby improving the overpotential by searching for an optimal catalyst. This method appears to be widely applicable since it is able to determine an optimal component and composition of electrocatalyst without obvious restriction to the types of catalysts to which it can be applied.

Citrus junos Tanaka Peel Extract and Its Bioactive Naringin Reduce Fine Dust-Induced Respiratory Injury Markers in BALB/c Male Mice.

Particulate matter (PM) 10 refers to fine dust with a diameter of less than 10 µm and induces apoptosis and inflammatory responses through oxidative stress. Citrus junos Tanaka is a citrus fruit and contains bioactive flavonoids including naringin. In the present study, we aimed to identify the preventive effect of Citrus junos Tanaka peel extract (CPE) against PM10-induced lung injury. As a proof of concept, NCI-H460 cells were treated with CPE (800 µg/mL, 12 h) in conjunction with PM10 to examine intracellular antioxidative capacity in the pulmonary system. In an in vivo model, male BALB/c mice (n = 8/group) were randomly assigned into five groups: NEG (saline-treated), POS (PM10 only), NAR (PM10 + naringin, 100 mg/kg), CPL (PM10 + CPE low, 100 mg/kg), and CPH (PM10 + CPE high, 400 mg/kg). Intervention groups received dietary supplementations for 7 days followed by PM10 exposure (100 mg/kg, intranasal instillation). Compared to the NEG, the CPE decreased to 22% of the ROS generation and significantly increased cell viability in vitro. The histological assessments confirmed that pulmonary damages were alleviated in the PM10 + CPL group compared to the POS. Pro-inflammatory cytokines and NF-κB/apoptosis signaling-related markers were decreased in the PM10 + CPL group compared to the POS. These results indicated that CPE showed promising efficacy in preventing pulmonary injuries in vivo. Such protection can be explained by the anti-oxidative capacity of CPE, likely due to its bioactives, including naringin (7.74 mg/g CPE). Follow-up human intervention, as well as population-level studies, will further shed light on the preventive efficacy of CPE against pulmonary damage in humans.

High-Performance, Flexible NO2 Chemiresistors Achieved by Design of Imine-Incorporated n-Type Conjugated Polymers.

Flexible and mechanically robust gas sensors are the key technologies for wearable and implantable electronics. Herein, the authors demonstrate the high-performance, flexible nitrogen dioxide (NO2 ) chemiresistors using a series of n-type conjugated polymers (CPs: PNDIT2/IM-x) and a polymer dopant (poly(ethyleneimine), PEI). Imine double bonds (C = N) are incorporated into the backbones of the CPs with different imine contents (x) to facilitate strong and selective interactions with NO2 . The PEI provides doping stability, enhanced electrical conductivity, and flexibility. As a result, the NO2 sensors with PNDIT2/IM-0.1 and PEI (1:1 by weight ratio) exhibit outstanding sensing performances, such as excellent sensitivity (ΔR/Rb = 240% @ 1 ppm), ultralow detection limit (0.1 ppm), high selectivity (ΔR/Rb < 8% @ 1 ppm of interfering analytes), and high stability, thereby outperforming other state-of-the-art CP-based chemiresistors. Furthermore, the thin film of PNDIT2/IM-0.1 and PEI blend is stretchable and mechanically robust, providing excellent flexibility to the NO2 sensors. Our study contributes to the rational design of high-performance flexible gas sensors.

Are high medical costs incurred by people with disabilities excessive?: An empirical analysis of Korean National Health Insurance Data.

A crude comparison of medical costs between people with disabilities (PWD) and without disabilities (PWoD) shows a much higher expenditure among PWD and such results have been a cause for further stigmatization. This study aims to empirically analyze whether the medical costs for PWD are actually high when characteristics related to medical costs are adjusted. Ten percent of the total population was randomly selected from the Korean National Health Insurance (NHI) Database in 2016. A crude comparative analysis was performed to calculate the medical cost of PWD and PWoD. A subsequent multiple regression analysis was conducted to adjust factors affecting the medical costs such as socioeconomic status, disease, and health behavior-related characteristics. The medical cost for PWD was 3.6 times higher than that for PWoD by crude comparison. However, after multiple regression analysis, margin of difference decreased to 1.5 times although the cost for PWD remained higher. Substantial decrease in higher medical costs for PWD after multiple analyses compared to crude analysis implies that additional adjustment using variables such as disease severity, not available in the NHI database, may predict a further reduction in differences. Thus, it is difficult to determine that the medical expenditure for PWD is excessive.

Investigation of Early Stage of Carbon Nanotube Growth on Plasma-Pretreated Inconel Plates and Comparison with Other Superalloys as Substrates.

We investigate the early stage of carbon nanotube (CNTs) growth on Inconel 600 to address the effect of pretreatments such as annealing and plasma pretreatment on growth behavior. In addition, we compare the growth results to other Ni-based superalloys including Invar 42 and Hastelloy C276. The growth substrates were prepared using mechanical polish, thermal annealing and plasma pretreatment. The air annealing was performed at 725 °C for 10 min and plasma pretreatment was subsequently undergone with 10.5 W at 500 °C for 30 min. The annealed and plasma-pretreated substrates exhibited different surface morphologies on the surface and enhanced growth behavior of CNT was observed from the region of particulate surface. The optimized growth temperature, which produces the highest CNT height, was determined at 525 °C for Ni and Inconel 600 and 625 °C for Invar 42 and Hastelloy C276 substrates. The difference of optimal growth temperature is expected to the existence of high temperature elements such as Mn or Mo in the alloys. X-ray diffraction spectroscopy revealed that the formation of roughened oxide layers caused by the pretreatments would promote the nucleation and growth of the CNTs.

Impact of Continuous Care on Health Outcomes and Cost for Type 2 Diabetes Mellitus: Analysis Using National Health Insurance Cohort Database.

BACKGROUND: The objective of the study was to determine the impact of continuous care on health outcomes and cost of type 2 diabetes mellitus (T2DM) in Korea. METHODS: A nationwide retrospective, observational case-control study was conducted. Continuity of treatment was measured using Continuity of Care (COC) score. Information of all patients newly diagnosed with T2DM in 2004 was retrieved from the National Health Insurance database for the period of 2002 to 2013. The study examined 2,373 patients after applying exclusion criteria, such as for patients who died from conditions not related to T2DM. Statistical analyses were performed using frequency distribution, simple analysis (t-test and chi-squared test), and multi-method analysis (simple linear regression, logistic regression, and survival analysis). RESULTS: The overall COC score was 0.8±0.24. The average incidence of diabetic complications was 0.39 per patient with a higher COC score, whereas it was 0.49 per patient with a lower COC score. In both survival and logistic analyses, patients who had high COC score were significantly less likely to have diabetic complications (hazard ratio, 0.69; 95% confidence interval, 0.54 to 0.88). The average medical cost was approximately 3,496 United States dollar (USD) per patient for patients with a higher COC score, whereas it was 3,973 USD per patient for patients with a lower COC score during the 2006 to 2013 period, with a difference of around 477 USD, which is statistically significant after adjusting for other factors (ß=-0.152). CONCLUSION: Continuity of care for diabetes significantly reduced health complications and medical costs from patients with T2DM.

Reliability and Validity of the Appropriateness Evaluation Protocol for Public Hospitals in Korea.

OBJECTIVES: This study was conducted to assess the applicability of the Appropriateness Evaluation Protocol (AEP) for public hospitals in Korea. METHODS: In May 2016, 1500 admission claims were collected from Korean public district hospitals using stratified random sampling. Of these claims, 560 admissions to 37 hospitals were retrieved for analysis. Medical records administrators determined the appropriateness of admission using the criteria detailed in the AEP, and a physician separately assessed the appropriateness of admission based on her clinical judgment. To examine the applicability of the AEP, the concordance of the decisions made between a pair of AEP reviewers and between an AEP reviewer and a physician reviewer was compared. RESULTS: The results showed an almost perfect inter-rater agreement between the AEP reviewers and a moderate agreement between the AEP reviewers and the physician. The sensitivity and specificity of the AEP were calculated as 0.86 and 0.56, respectively. CONCLUSIONS: Our findings suggest that the AEP could potentially be applied to Korean public hospitals as a reliable and valid instrument for assessing the appropriateness of admissions.

The Effect of Diagnosis-Related Groups on the Shift of Medical Services From Inpatient to Outpatient Settings: A National Claims-Based Analysis.

The purpose of this study was to determine whether the introduction of diagnosis-related groups (DRGs) shifted the medical services from inpatient to outpatient settings. Using a difference-in-difference analysis, the changes in length of stay, outpatient visit days within 30 days before hospitalization, and outpatient visit days within 30 days after hospital discharge were evaluated. The length of stay was reduced after the DRG policy, consistent with previous studies. Outpatient visit days within 30 days before a hospital admission increased significantly after the policy change. In addition, outpatient visit days within 30 days after a hospital discharge increased in all the medical institutions excluding hospitals. The study findings are consistent with the expectation that providers respond to changes in the payment system to protect or enhance their economic interests. Health care providers in Korea responded to the DRG policy by reducing the intensity of inpatient treatment and transferring costs to outpatient settings.

A Spatial Analysis of Preventable Hospitalization for Ambulatory Care Sensitive Conditions and Regional Characteristics in South Korea.

Hospitalization rates for ambulatory care sensitive conditions (ACSCs) can indicate the accessibility of a community's primary care. We examined regional variation in ACSC hospitalization rates and identified associated factors. ACSC hospitalization rates in the 232 districts in 2013 ranged from 4.08 to 101.53 per 1000 adults. Spatial analysis showed that none of the 24 highest rate districts were located near Seoul, whereas 80% of the 45 lowest rate districts were, suggesting health care inequality between people living near Seoul and in other areas. Regression analysis showed significantly higher ACSC hospitalization rates in districts with higher elderly (ß = 0.94) and low-income populations (ß = 2.25), more remote areas (ß = 0.29), and more hospital beds (ß = 0.03). The number of primary care clinics was negatively associated with ACSC hospitalization (ß = -1.37). For these variables, geographically weighted regression analysis provided local regression coefficients, useful for developing region-specific strategies to reduce ACSC hospitalization.

Effect of health insurance type on health care utilization in patients with hypertension: a national health insurance database study in Korea.

BACKGROUND: Higher utilization of healthcare services has been observed among individuals who receive public aid compared to individuals who do not receive public aid in many countries. However, no systematic investigations have explored whether this pattern of higher utilization persists after correcting for a number of factors in Korea. In this study, we sought to examine whether the type of health insurance, wage-based contributory insurance (Health Insurance, HI) or government-subsidized public assistance (Medical Aid, MA), affects the utilization of inpatient services after controlling for baseline patient and institutional characteristics among patients with hypertension in Korea. METHODS: The Korean National Health Insurance claims database from 2006 and 2007 was used for analysis. To avoid biased estimates, we determined the most appropriate type of multivariate model for each outcome variable: a logistic regression model for the likelihood of hospitalization, a zero-inflated negative binomial model for the length of stay (LOS), and a generalized linear model with a log-link function for hospitalization costs. RESULTS: Adjusted odds ratio (OR) and factor changes showed that MA patients (n = 21,539) had a significantly higher likelihood of hospitalization (OR: 1.41-1.71), average LOS per patient (factor change: 1.31-1.42), and hospitalization costs per patient (factor change: 1.10-1.41) compared to HI patients (n = 304,027). CONCLUSIONS: The pattern of higher healthcare utilization among MA patients persists even after controlling for baseline health conditions. This finding confirms that the type of health insurance affects the utilization of healthcare resources, and suggests that effective strategies are necessary to prevent the potential overutilization of inpatient care by MA patients with hypertension in Korea.

Effects of health insurance on non-working married women's medical care use and bed days at home.

BACKGROUND: This study examines whether bed days are alternative methods to medical care use for treating a particular illness. If bed days at home are considered as an alternative to medical treatment, then medical care use and bed days at home should be influenced by an individual's health insurance status. METHOD: This study uses data from the 2003 Medical Expenditure Panel Survey (MEPS) on medical care use and bed days at home for each contracted illness of non-working married women. RESULTS: The results suggest that the health insurance status of non-working married women has considerable influence on their choice between medical care use and bed days at home. In addition, those with health insurance are more likely to use medical care and less likely to use bed days at home, but they tend to avoid the simultaneous use of medical care and bed days at home. CONCLUSIONS: In contrast to previous studies' findings indicating that absences from work and medical care use among working males may be complements, this study's results for non-working married women without health insurance suggest that they use rest and medical treatment as substitutes, not complements.

Disease coding errors by health care organizations: effects of a government quality intervention.

Disease coding errors in claims data can cause serious problems for financing, reimbursement systems, public health surveillance and health research. This study analysed a government intervention to improve coding accuracy of health care organizations in South Korea. The intervention was implemented in 1997 by 226 organizations that had submitted erroneous claims in 1996 for five selected diseases. In 1998, 94% of these organizations eliminated coding errors for these diseases. Those organizations least responsive to the intervention were tertiary hospitals, those publicly owned, and those with other complex organizational characteristics. Overall, this simple intervention appeared extremely effective, and wider adoption of such techniques should be explored.