MXene Hybrid Nanosheet of WS2/Ti3C2 for Electrocatalytic Hydrogen Evolution Reaction.

Designing low-cost hybrid electrocatalysts for hydrogen production is of significant importance. Recently, MXene-based materials are being increasingly employed in energy storage devices owing to their layered structure and high electrical conductivity. In this study, we propose a facile hydrothermal strategy for producing WS2/Ti3C2 nanosheets that function as electrocatalysts in the hydrogen evolution reaction (HER). WS2 provides a high surface area and active sites for electrocatalytic activity, whereas MXene Ti3C2 facilitates charge transfer. As a result, the synthesized WS2/Ti3C2 offers an increased surface area and exhibits an enhanced electrocatalytic activity in acidic media. The WS2/Ti3C2 (10%) catalyst exhibited a low onset potential of -150 mV versus RHE for the HER and a low Tafel slope of ∼62 mV dec-1. Moreover, WS2/Ti3C2 (10%) exhibited a double-layer capacitance of 1.2 mF/cm-2, which is 3 and 6 times greater than those of bare WS2 and Ti3C2, respectively. This catalyst also maintained a steady catalytic activity for the HER for over 1000 cycles.

Structural and functional investigation of GajB protein in Gabija anti-phage defense.

Bacteriophages (phages) are viruses that infect bacteria and archaea. To fend off invading phages, the hosts have evolved a variety of anti-phage defense mechanisms. Gabija is one of the most abundant prokaryotic antiviral systems and consists of two proteins, GajA and GajB. GajA has been characterized experimentally as a sequence-specific DNA endonuclease. Although GajB was previously predicted to be a UvrD-like helicase, its function is unclear. Here, we report the results of structural and functional analyses of GajB. The crystal structure of GajB revealed a UvrD-like domain architecture, including two RecA-like core and two accessory subdomains. However, local structural elements that are important for the helicase function of UvrD are not conserved in GajB. In functional assays, GajB did not unwind or bind various types of DNA substrates. We demonstrated that GajB interacts with GajA to form a heterooctameric Gabija complex, but GajB did not exhibit helicase activity when bound to GajA. These results advance our understanding of the molecular mechanism underlying Gabija anti-phage defense and highlight the role of GajB as a component of a multi-subunit antiviral complex in bacteria.

Prognostic value of resting heart rate in predicting undiagnosed diabetes in adults: Korean National Health and Nutrition Examination Survey 2008-2018.

BACKGROUND AND AIM: Although resting heart rate (RHR) is associated with prevalence and incidence of diabetes, whether it is associated with undiagnosed diabetes is still unclear. We aimed to investigate whether the RHR is associated with the prevalence of undiagnosed diabetes in a large Korean national dataset. METHODS AND RESULTS: The Korean National Health and Nutrition Examination Survey data from 2008 to 2018 were used. After screening, 51,637 participants were included in this study. The odds ratios and 95% confidence intervals (CIs) for undiagnosed diabetes were calculated using multivariable-adjusted logistic regression analyses. Analyses showed that participants with a RHR of ≥90 bpm showed a 4.00- (95% CI: 2.77-5.77) and 3.21-times (95% CI: 2.01-5.14) higher prevalence of undiagnosed diabetes for men and women, respectively, than those with a RHR of <60 bpm. The linear dose-response analyses showed that each 10-bpm increment in RHR was associated with a 1.39- (95% CI: 1.32-1.48) and 1.28-times (95% CI: 1.19-1.37) higher prevalence of undiagnosed diabetes for men and women, respectively. In the stratified analyses, the positive association between RHR and the prevalence of undiagnosed diabetes was tended to be stronger among those who were younger (age: <40 years) and lean (BMI: <23 kg/m2). CONCLUSIONS: Elevated RHR was significantly associated with a higher prevalence of undiagnosed diabetes in Korean men and women, independent of demographic, lifestyle, and medical factors. Accordingly, the value of RHR as a clinical indicator and health marker, especially in reducing the prevalence of undiagnosed diabetes, is suggestible.

High energy dissipation-based process to improve the rheological properties of bentonite drilling muds by reducing the particle size.

Drilling mud is a multi-phase fluid that is used in the petroleum drilling process. Bentonite is the most important constituent of drilling mud; it endows the drilling mud with its rheological behaviors, such as viscosity, yield stress, and shear thinning. The process of manufacturing microscale bentonite at the nanoscale level is very promising for commercializing nano-based drilling mud. In contrast to the conventional method using the impeller, bentonite was manufactured in its nanoparticle state in the present work through ultrasonic and homogenizer processes in the solution state. In case of the ultrasonic process, the viscosity increase in the low shear rate region before and after processing of the 5 wt% bentonite-based mud and the rheological properties in the presence of polymer additive were compared. In case of the homogenizer process, the rheological properties of 3 wt% bentonite-based mud employed through the homogenizer process and 5 wt% mud prepared generally were compared. Both processes reported improvement of rheological properties, in which shear thinning behavior strongly occurred when particle size decreased through FE-SEM, TEM image analysis, and particle size analyzer. A regularized Herschel-Bulkley model suitable for rheological quantitative explanation of drilling mud including yield stress was selected. The homogenizer process has the potential to be applied in the petroleum drilling industry for large-scale production, and the mechanism was confirmed by numerical analyses. In conclusion, we presented a simple and easy-to-apply process to rapidly produce nano-based drilling mud.

Transition Metal Ion Doping on ZIF-8 Enhances the Electrochemical CO2 Reduction Reaction.

The electrochemical reduction of CO2  to diverse value-added chemicals is a unique, environmentally friendly approach for curbing greenhouse gas emissions while addressing sluggish catalytic activity and low Faradaic efficiency (FE) of electrocatalysts. Here, zeolite-imidazolate-frameworks-8 (ZIF-8) containing various transition metal ions-Ni, Fe, and Cu-at varying concentrations upon doping are fabricated for the electrocatalytic CO2 reduction reaction (CO2 RR) to carbon monoxide (CO) without further processing. Atom coordination environments and theoretical electrocatalytic performance are scrutinized via X-ray absorption spectroscopy (XAS) and density functional theory (DFT) calculations. Upon optimized Cu doping on ZIF-8, Cu0.5 Zn0.5 /ZIF-8 achieves a high partial current density of 11.57 mA cm-2 and maximum FE for CO of 88.5% at -1.0 V (versus RHE) with a stable catalytic activity over 6 h. Furthermore, the electron-rich sp2 C atom facilitates COOH* promotion after Cu doping of ZIF-8, leading to a local effect between the zinc-nitrogen (Zn-N4 ) and copper-nitrogen (Cu-N4 ) moieties. Additionally, the advanced CO2 RR pathway is illustrated from various perspectives, including the pre-H-covered state under the CO2 RR. The findings expand the pool of efficient metal-organic framework (MOF)-based CO2 RR catalysts, deeming them viable alternatives to conventional catalysts.

[Hyponatremic Seizure after Ingestion of an Oral Sulfate Tablet for Bowel Preparation for Colonoscopy].

The oral sulfate tablet (OST), commercially available as Orafang® (Pharmbio Korea Co., Seoul, Korea) in Korea, is being used increasingly because of its bowel-cleansing efficacy, safety, and tolerability in adults undergoing colonoscopy. Other bowel cleansing agents, such as polyethylene glycol and sodium picosulfate/magnesium citrate, can cause plasma volume depletion and electrolyte disturbances, such as hyponatremia. On the other hand, the OST has never been reported to cause hyponatremia in Korea. To our knowledge, the authors experienced the first case of hyponatremic seizure in an 81-year-old woman to whom an OST was administered for bowel preparation before a colonoscopy. After ingesting the OST, she presented with seizure, confusion, and dyspnea. Upon arrival, her serum sodium level was 120 mEq/L, and the urine osmolality and sodium levels were 449 mOsm/kg and 253 mOsm/kg, respectively; chest imaging suggested pulmonary edema. The associated symptoms disappeared following treatment with an intravenous injection of normal saline and 3% NaCl to normalize the sodium level. This case shows that the OST can cause hyponatremia and other severe complications related to hyponatremia.

The structure of AcrIE4-F7 reveals a common strategy for dual CRISPR inhibition by targeting PAM recognition sites.

Bacteria and archaea use the CRISPR-Cas system to fend off invasions of bacteriophages and foreign plasmids. In response, bacteriophages encode anti-CRISPR (Acr) proteins that potently inhibit host Cas proteins to suppress CRISPR-mediated immunity. AcrIE4-F7, which was isolated from Pseudomonas citronellolis, is a fused form of AcrIE4 and AcrIF7 that inhibits both type I-E and type I-F CRISPR-Cas systems. Here, we determined the structure of AcrIE4-F7 and identified its Cas target proteins. The N-terminal AcrIE4 domain adopts a novel α-helical fold that targets the PAM interaction site of the type I-E Cas8e subunit. The C-terminal AcrIF7 domain exhibits an αß fold like native AcrIF7, which disables target DNA recognition by the PAM interaction site in the type I-F Cas8f subunit. The two Acr domains are connected by a flexible linker that allows prompt docking onto their cognate Cas8 targets. Conserved negative charges in each Acr domain are required for interaction with their Cas8 targets. Our results illustrate a common mechanism by which AcrIE4-F7 inhibits divergent CRISPR-Cas types.

Surface-Tailored Medium Entropy Alloys as Radically Low Overpotential Oxygen Evolution Electrocatalysts.

Numerous studies have explored new materials for electrocatalysts, but it is difficult to discover materials that surpass the catalytic activity of current commercially available noble metal electrocatalysts. In contrast to conventional transition metal alloys, high-entropy alloys (HEAs) have immense potential to maximize their catalytic properties because of their high stability and compositional diversity as oxygen evolution reactions (OERs). This work presents medium-entropy alloys (MEAs) as OER electrocatalysts to simultaneously satisfy the requirement of high catalytic activity and long-term stability. The surface of MEA electrocatalyst is tailored to suit the OER via anodizing and cyclic voltammetry activation methods. Optimized electrical properties and hydrophilicity of the surface enable an extremely low overpotential of 187 mV for achieving the current density of 10 mA cm-2 alkaline media. Furthermore, a combined photovoltaic-electrochemical system with MEA electrocatalyst and a perovskite/Si tandem solar cell exhibits a solar-to-hydrogen conversion efficiency of 20.6% for an unassisted hydrogen generation system. These results present a new pathway for designing sustainable high efficiency water splitting cells.

WS2-WC-WO3 nano-hollow spheres as an efficient and durable catalyst for hydrogen evolution reaction.

Transition metal dichalcogenides (TMDs), transition metal carbides (TMCs), and transition metal oxides (TMOs) have been widely investigated for electrocatalytic applications owing to their abundant active sites, high stability, good conductivity, and various other fascinating properties. Therefore, the synthesis of composites of TMDs, TMCs, and TMOs is a new avenue for the preparation of efficient electrocatalysts. Herein, we propose a novel low-cost and facile method to prepare TMD-TMC-TMO nano-hollow spheres (WS2-WC-WO3 NH) as an efficient catalyst for the hydrogen evolution reaction (HER). The crystallinity, morphology, chemical bonding, and composition of the composite material were comprehensively investigated using X-ray diffraction, Raman spectroscopy, field emission scanning electron microscopy, and X-ray photoelectron spectroscopy. The results confirmed the successful synthesis of the WS2-WC-WO3 NH spheres. Interestingly, the presence of nitrogen significantly enhanced the electrical conductivity of the hybrid material, facilitating electron transfer during the catalytic process. As a result, the WS2-WC-WO3 NH hybrid exhibited better HER performance than the pure WS2 nanoflowers, which can be attributed to the synergistic effect of the W-S, W-C, and W-O bonding in the composite. Remarkably, the Tafel slope of the WS2-WC-WO3 NH spheres was 59 mV dec-1, which is significantly lower than that of the pure WS2 NFs (82 mV dec-1). The results also confirmed the unprecedented stability and superior electrocatalytic performance of the WS2-WC-WO3 NH spheres toward the HER, which opens new avenues for the preparation of low-cost and highly effective materials for energy conversion and storage applications.

Regulation of Dual Activity of Ascorbate Peroxidase 1 From Arabidopsis thaliana by Conformational Changes and Posttranslational Modifications.

Ascorbate peroxidase (APX) is an important reactive oxygen species (ROS)-scavenging enzyme, which catalyzes the removal of hydrogen peroxide (H2O2) to prevent oxidative damage. The peroxidase activity of APX is regulated by posttranslational modifications (PTMs), such as S-nitrosylation, tyrosine nitration, and S-sulfhydration. In addition, it has been recently reported that APX functions as a molecular chaperone, protecting rice against heat stress. In this study, we attempted to identify the various functions of APX in Arabidopsis and the effects of PTMs on these functions. Cytosol type APX1 from Arabidopsis thaliana (AtAPX1) exists in multimeric forms ranging from dimeric to high-molecular-weight (HMW) complexes. Similar to the rice APX2, AtAPX1 plays a dual role behaving both as a regular peroxidase and a chaperone molecule. The dual activity of AtAPX1 was strongly related to its structural status. The main dimeric form of the AtAPX1 protein showed the highest peroxidase activity, whereas the HMW form exhibited the highest chaperone activity. Moreover, in vivo studies indicated that the structure of AtAPX1 was regulated by heat and salt stresses, with both involved in the association and dissociation of complexes, respectively. Additionally, we investigated the effects of S-nitrosylation, S-sulfhydration, and tyrosine nitration on the protein structure and functions using gel analysis and enzymatic activity assays. S-nitrosylation and S-sulfhydration positively regulated the peroxidase activity, whereas tyrosine nitration had a negative impact. However, no effects were observed on the chaperone function and the oligomeric status of AtAPX1. Our results will facilitate the understanding of the role and regulation of APX under abiotic stress and posttranslational modifications.

Measurement of Ankle Joint Movements Using IMUs during Running.

Gait analysis has historically been implemented in laboratory settings only with expensive instruments; yet, recently, efforts to develop and integrate wearable sensors into clinical applications have been made. A limited number of previous studies have been conducted to validate inertial measurement units (IMUs) for measuring ankle joint kinematics, especially with small movement ranges. Therefore, the purpose of this study was to validate the ability of available IMUs to accurately measure the ankle joint angles by comparing the ankle joint angles measured using a wearable device with those obtained using a motion capture system during running. Ten healthy subjects participated in the study. The intraclass correlation coefficient (ICC) and standard error of measurement were calculated for reliability, whereas the Pearson coefficient correlation was performed for validity. The results showed that the day-to-day reliability was excellent (0.974 and 0.900 for sagittal and frontal plane, respectively), and the validity was good in both sagittal (r = 0.821, p < 0.001) and frontal (r = 0.835, p < 0.001) planes for ankle joints. In conclusion, we suggest that the developed device could be used as an alternative tool for the 3D motion capture system for assessing ankle joint kinematics.

Cost-Effectiveness of Tiotropium in Elderly Patients with Severe Asthma Using Real-World Data.

BACKGROUND: Tiotropium has the potential to alleviate asthmatic symptoms caused by the aging of lungs. However, few studies have focused on specific treatments for elderly patients with asthma. OBJECTIVES: To estimate the cost-effectiveness of adding tiotropium to inhaled corticosteroids and long-acting beta-agonists in elderly patients with severe asthma using real-world data. METHODS: Phase I was a retrospective cohort study using the National Health Insurance claims data to measure clinical and economic outcomes. In phase II, a Markov model was constructed to evaluate cost-effectiveness from Korean health care system perspective, based on phase I, including 2 health states, and an asthma exacerbation event. We estimated cost given in 2018 US dollars, quality-adjusted life-years (QALYs), and incremental cost-effectiveness ratio. Subgroup analyses for patients with poorly controlled symptoms (frequent short-acting beta-agonist users; frequent exacerbators) were performed. RESULTS: In elderly patients with severe asthma, the incremental cost and effectiveness in the tiotropium group compared with the inhaled corticosteroid and long-acting beta-agonist group were $2281 and 0.038 QALYs, respectively. The incremental cost-effectiveness ratio was $60,074/QALY, indicating that the addition of tiotropium is not a cost-effective alternative. Meanwhile, 2 subgroups with poorly controlled symptoms showed that adding tiotropium is a cost-effective alternative (frequent short-acting beta-agonist users $4078/QALY; frequent exacerbators $8332/QALY). CONCLUSIONS: Tiotropium shows a higher cost-effectiveness profile when applied to elderly patients with uncontrolled symptoms. These results using real-world evidence provide information beyond the clinical outcomes reported by randomized controlled trials, providing a complementary ground in establishing the reimbursement criteria of tiotropium for elderly patients with severe asthma.

Breath Acetone Measurement-Based Prediction of Exercise-Induced Energy and Substrate Expenditure.

The purpose of our study was to validate a newly developed breath acetone (BrAce) analyzer, and to explore if BrAce could predict aerobic exercise-related substrate use. Six healthy men ran on a treadmill at 70% of maximal oxygen consumption (VO2max) for 1 h after two days of a low-carbohydrate diet. BrAce and blood ketone (acetoacetate (ACAC), beta-hydroxybutyrate (BOHB)) levels were measured at baseline and at different time points of post-exercise. BrAce values were validated against blood ketones and respiratory exchange ratio (RER). Our results showed that BrAce was moderately correlated with BOHB (r = 0.68, p < 0.01), ACAC (r = 0.37, p < 0.01) and blood ketone (r = 0.60, p < 0.01), suggesting that BrAce reflect blood ketone levels, which increase when fat is oxidized. Furthermore, BrAce also negatively correlated with RER (r = 0.67, p < 0.01). In our multiple regression analyses, we found that when BMI and VO2max were added to the prediction model in addition to BrAce, R2 values increased up to 0.972 at rest and 0.917 at 1 h after exercise. In conclusion, BrAce level measurements of our BrAce analyzer reflect blood ketone levels and the device could potentially predict fat oxidation.

Incidence and risk factors of subsequent osteoporotic fracture: a nationwide cohort study in South Korea.

This study analyzed the incidence and risk factors of subsequent osteoporotic fractures in South Korea. The results showed that the incidence rate of subsequent fractures within 24 months was 10.23 per 100 person-years. Additionally, the index hip fracture site was a significant risk factor for a subsequent fracture. PURPOSE: To identify and analyze the incidence and risk factors of subsequent osteoporotic fractures in South Korea. METHODS: This retrospective cohort study analyzed data from the National Health Insurance Review and Assessment claims database from 2012 to 2017. Men and women with osteoporosis, aged ≥50 years, with index fractures between July 1, 2014, and July 1, 2015, were included. The incidence rate of subsequent fractures was calculated by determining the number of second event within 2 years from the index fracture. To identify the risk factors for subsequent fractures, we applied the Cox proportional hazard model to estimate the hazard ratios (HRs). RESULTS: Of the 73,717 patients with osteoporotic fractures, 13,203 (17.91%) had a subsequent fracture. The incidence rate of subsequent fractures within 24 months was 10.23/100 person-years. The index fracture site was a significant risk factor for a subsequent fracture, with the hip showing the highest risk (HR, 7.51; 95% confidence interval [CI], 6.77-8.34), followed by the vertebra (HR, 1.99; 95% CI, 1.91-2.06). The risk of subsequent fractures increased with a higher Charlson Comorbidity Index (CCI) score (CCI score ≥ 5: HR, 1.79; 95% CI, 1.67-1.92). CONCLUSION: The incidence rate of subsequent osteoporotic fractures in South Korea is similar or higher than that reported in the USA and Europe. A hip fracture within the prior 2 years, relative to other fracture sites, significantly increased the risk of subsequent fractures in osteoporosis patients. Patients who have these risk factors need closer disease management to prevent subsequent fractures.

Economic burden of subsequent fracture in osteoporosis patients in South Korea.

OBJECTIVES: This study aimed to assess the economic burden of subsequent fracture in osteoporosis patients with incident fracture. METHODS: The authors conducted a retrospective cohort analysis of the South Korean national health insurance claims data. Study subjects included osteoporosis patients aged ≥50 with incident fracture (July 1, 2014-June 30, 2015). Fracture-related 1-year healthcare cost was evaluated after incident fracture for patients with and without subsequent fracture, defined as a fracture occurring within 2 years from incident fracture at a different site or at the same site after 6-months washout period. Per-patient-per-month (PPPM) cost was calculated by dividing each patient's cumulative healthcare cost until subsequent fracture with time-to-subsequent-fracture. For the patients without subsequent fracture, PPPM cost equaled 1-year monthly cost. A generalized linear model (GLM) was used to estimate the ratio of increase in healthcare cost to assess the economic impact of subsequent fracture. RESULTS: A total of 73,717 osteoporosis patients with incident fracture were identified, consisting of 52.1% vertebral, 1.9% hip, and 46.0% non-vertebral-non-hip fractures. Subsequent fracture occurred in 17.9% of patients with average time-to-subsequent-fracture of 256 days. Patients with subsequent fracture had significantly higher 1-year healthcare cost after incident fracture than those without subsequent fracture ($4,307 vs $1,721) and the difference was greater in PPPM cost ($930 vs $141). GLM analysis showed that having subsequent fracture increased both 1-year healthcare cost and PPPM cost by 1.91-fold (95% CI = 1.87-1.95) and 6.14-fold (95% CI = 5.99-6.28), respectively. CONCLUSIONS: Subsequent fracture imposes a substantial burden on osteoporosis patients and, therefore, more efforts are needed for preventing subsequent fracture among osteoporosis patients.

Synthesis of Diatomite-Based Mesoporous Wool-Ball-Like Microspheres and Their Application for Toluene Total Oxidation Reaction.

Diatomite (DE) has attracted considerable attention owing to its abundance, low cost, and potential for a wide variety of applications. This work reports the development of mesoporous wool-ball-like (WBL) microspheres from natural DE through a simple hydrothermal treatment. We discovered that the presence of cetyltrimethylammonium bromide is a prerequisite for generating monodispersed WBL microspheres. The mechanism for the transformation of pristine DE into mesoporous microspheres through dissolution-recrystallization was clearly investigated. Interestingly, the microspheres exhibited a specific surface area 25-60 times larger than that of the pristine DE. The application of WBL microsphere DE as an effective support for metallic catalysts in the toluene total oxidation reaction was demonstrated.

Functional properties and the oligomeric state of alkyl hydroperoxide reductase subunit F (AhpF) in Pseudomonas aeruginosa.

Alkyl hydroperoxide reductase subunit F (AhpF) is a well-known flavoprotein that transfers electrons from pyridine nucleotides to the peroxidase protein AhpC via redox-active disulfide centers to detoxify hydrogen peroxide. However, study of AhpF has historically been limited to particular eubacteria, and the connection between the functional and structural properties of AhpF remains unknown. The present study demonstrates the dual function of Pseudomonas aeruginosa AhpF (PaAhpF) as a reductase and a molecular chaperone. It was observed that the functions of PaAhpF are closely linked with its structural status. The reductase and foldase chaperone function of PaAhpF predominated for its low-molecular-weight (LMW) form, whereas the holdase chaperone function of PaAhpF was found associated with its high-molecular-weight (HMW) complex. Further, the present study also demonstrates the multiple function of PaAhpF in controlling oxidative and heat stresses in P. aeruginosa resistance to oxidative and heat stress.

Decoding the Capability of Lactobacillus plantarum W1 Isolated from Soybean Whey in Producing an Exopolysaccharide.

This study aims at producing exopolysaccharides (EPS) from a lactic acid bacterial strain. The soybean whey-isolated Lactobacillus plantarum W1 (EPS-W1), which belongs to genus Lactobacillus, is identified using the phenylalanyl-tRNA sequencing method. Of all the examined strains, R-49778 (as numbered by BCCM/LMG Bacteria Collection, Ghent University, Belgium) showed the highest capability of producing exopolysaccharides. Structural characterization revealed a novel exopolysaccharide consisting of repeating units of →6)-d-Glcp-(1→; →3)-d-Manp-(1→; →3)-d-Glcp-(1→ and a branch of →6)-d-Manp-(1→; →2)-d-Glcp-(1→. This discovery opens up avenues for the production of EPS for food industries, functional foods, and biomedical applications.