Association between cesarean section rate and maternal age in twin pregnancies.

OBJECTIVES: To evaluate the effect of maternal age to the cesarean section rate of twin pregnancies in late preterm and term gestation. METHODS: A retrospective study was performed on twin pregnancies delivered at Seoul National University Bundang Hospital from June 2003 to December 2020. Preterm births before 34 weeks of gestation were excluded, and only live births were analyzed. The patients were classified into four groups according to maternal age (<30, 30-34, 35-39, and ≥40 years). The primary outcome was the rate of cesarean section. RESULTS: The median value of maternal body mass index, the rate of assisted reproductive technology, dichorionic twin pregnancy, preeclampsia, and gestational diabetes increased significantly according to the maternal age group (all p<0.05). Among a total of 2,075 twin pregnancies, the rates of cesarean section were 65, 74, 80, and 95% for groups with maternal age under 30, 30-34, 35-39, and ≥40 years, respectively (p<0.001). The cesarean section rates after a trial of labor were 22, 22, 28, and 63%, respectively (p=0.032). Maternal old age was an independent risk factor for cesarean section after a trial of labor in both nulliparous and multiparous women after adjusting for confounding factors. CONCLUSIONS: The rate of cesarean section in twin pregnancies significantly increased as maternal age increased, even in multiparous women.

Versatile Strategy for Tuning ORR Activity of a Single Fe-N4 Site by Controlling Electron-Withdrawing/Donating Properties of a Carbon Plane.

Replacement of Pt-based oxygen reduction reaction (ORR) catalysts with non-precious metal catalysts (NPMCs) such as Fe/N/C is one of the most important issues in the commercialization of proton exchange membrane fuel cells (PEMFCs). Despite numerous studies on Fe/N/C catalysts, a fundamental study on the development of a versatile strategy is still required for tuning the kinetic activity of a single Fe-N4 site. Herein, we report a new and intuitive design strategy for tuning and enhancing the kinetic activity of a single Fe-N4 site by controlling electron-withdrawing/donating properties of a carbon plane with the incorporation of sulfur functionalities. The effect of electron-withdrawing/donating functionalities was elucidated by experimentation and theoretical calculations. Finally, the introduction of an oxidized sulfur functionality decreases the d-band center of iron by withdrawing electrons, thereby facilitating ORR at the Fe-N4 site by lowering the intermediate adsorption energy. Furthermore, this strategy can enhance ORR activity without a decrease in the stability of the catalyst. This simple and straightforward approach can be a cornerstone to develop optimum NPMCs for application in the cathodes of PEMFCs.

Investigation of the Support Effect in Atomically Dispersed Pt on WO3-x for Utilization of Pt in the Hydrogen Evolution Reaction.

Single-atom catalysts (SACs) have attracted growing attention because they maximize the number of active sites, with unpredictable catalytic activity. Despite numerous studies on SACs, there is little research on the support, which is essential to understanding SAC. Herein, we systematically investigated the influence of the support on the performance of the SAC by comparing with single-atom Pt supported on carbon (Pt SA/C) and Pt nanoparticles supported on WO3-x (Pt NP/WO3-x ). The results revealed that the support effect was maximized for atomically dispersed Pt supported on WO3-x (Pt SA/WO3-x ). The Pt SA/WO3-x exhibited a higher degree of hydrogen spillover from Pt atoms to WO3-x at the interface, compared with Pt NP/WO3-x , which drastically enhanced Pt mass activity for hydrogen evolution (up to 10 times). This strategy provides a new framework for enhancing catalytic activity for HER, by reducing noble metal usage in the field of SACs.

Bridging the Catalytic Turnover Gap Between Single-Atom Iron Nanozymes and Natural Enzymes by Engineering the First and Second Shell Coordination.

Single-atom nanozymes (SAzymes) constitute a promising category of enzyme-mimicking materials with outstanding catalytic performance. The performance of SAzymes improves through modification of the coordination environments around the metal center. However, the catalytic turnover rates of SAzymes, which are key measures of the effectiveness of active site modifications, remain lower than those of natural enzymes, especially in peroxidase-reactions. Here, the first and second shell coordination tuning strategy that yields SAzymes with structures and activities analogous to those of natural enzymes is reported. The optimized SAzyme exhibits a turnover rate of 52.7 s-1 and a catalytic efficiency of 6.97 × 105 M-1 s-1. A computational study reveals that axial S-ligands induce an alternative reaction mechanism, and SO2- functional groups provide hydrogen bonds to reduce the activation energy. In addition, SAzyme shows superior anti-tumor ability in vitro and in vivo. These results demonstrate the validity of coordination engineering strategies and the carcinostatic potential of SAzymes.

Boosting Alkaline Hydrogen Oxidation Activity of Ru Single-Atom Through Promoting Hydroxyl Adsorption on Ru/WC1- x Interfaces.

The sluggish kinetics of the hydrogen oxidation reaction (HOR) in alkaline conditions continue to pose a significant challenge for the practical implementation of anion-exchange membrane fuel cells. Developing single-atom catalysts can accelerate the pace of new HOR catalyst discovery for highly cost-effective and active HOR performance. However, single-atom catalysts (SACs) for the alkaline HOR have rarely been reported, and fundamental studies on the rational design of SACs are still required. Herein, the design of Ru SAC supported on the tungsten carbide (Ru SA/WC1- x ) via in situ high-temperature annealing strategy is reported. The resulting Ru SA/WC1- x catalyst exhibits remarkably enhanced HOR performance in alkaline media, a level of activity that can not be achieved with carbon-supported Ru SAC. Electrochemical results and density functional theory demonstrate that promoting the hydroxyl adsorption on Ru SA/WC1- x interfaces, which is derived from the low potential of zero charge of WC1- x support, has a significant effect on enhancing the HOR performance of SACs. This enhancement leads to 5.8 and 60.1 times higher Ru mass activity of Ru SA/WC1- x than Ru nanoparticles on carbon and Ru single-atom on N-doped carbon, respectively. This work provides new insights into the design of highly active SACs for alkaline HOR.

A Comparison of Ultrasound Imaging Texture Analyses During the Early Postpartum With the Mode of Delivery.

BACKGROUND: Breastfeeding is beneficial to infants. However, cesarean section is reported to be a risk factor for unsuccessful breastfeeding. RESEARCH AIMS: (1) To extract discriminating data from texture analysis of breast ultrasound images in the immediate postpartum period; and (2) to compare the analysis results according to delivery mode. METHODS: A cross-sectional, prospective non-experimental design with a questionnaire and observational components was used. Participants (N = 30) were women who delivered neonates at a center from September 2020 to December 2020. The participants underwent ultrasound examination of bilateral breasts 7-14 days after delivery. Ultrasound images were collected for texture analysis. A questionnaire about breastfeeding patterns was given to the participants on the day of the ultrasound examination. RESULTS: No significant differences were found in texture analysis between the breasts of participants who had undergone Cesarean section and vaginal deliveries. The mean volume of total human milk produced in 1 day was significantly greater in the vaginal delivery group than in the cesarean section group (M = 350.87 ml, SD = 183.83 vs. M = 186.20 ml, SD = 184.02; p = .017). The pain score due to breast engorgement measured subjectively by participants was significantly lower in the vaginal delivery group than in the cesarean section group (M = 2.8, SD = 0.86 vs. M = 3.4, SD = 0.63; p = .047). CONCLUSION: Texture analysis of breast ultrasound images did not demonstrate difference between the cesarean section and vaginal delivery groups in the immediate postpartum period; nevertheless, cesarean section was independently associated with less successful breastfeeding.

The Experience of Fertility Preservation in a Single Tertiary Center in Korea.

Objective: Oocyte (OC), embryo (EC), and ovarian tissue cryopreservation (OTC) are options for fertility preservation (FP) before going through gonadotoxic cancer treatment, or anticipated fertility decline in benign ovarian diseases, or for planned OC. The aim of this study is to report outcomes of FP in a single tertiary hospital in Korea. Methods: This is a retrospective study of OC, EC, and OTC cycles. All patients who visited or were referred to the infertility clinic at the Department of Obstetrics and Gynecology for the purpose of FP between 2010 and October 2021 were included. Results: A total of 564 controlled ovarian stimulation cycles were conducted in 416 women. Three hundred fifty-seven women underwent 494 OC cycles. Most patients were diagnosed with breast cancer (22.4%), followed by endometriomas (21.9%), and then by planned OC (20.7%). Cases of OC have increased over the years, peaking at 109 cycles in 2019 compared to one in 2010. Fifty-nine women underwent 70 EC cycles, and breast cancer (50.8%) was the most common indication. Repetitive OC and EC cycles were undergone in 92 and 9 women, respectively (mean number of repetition, 1.37 and 1.19 times in OC and EC, respectively), yielding a maximum number of 33 oocytes or 23 embryos being cryopreserved per patient. The utilization rate was 3.1% (11/357) in OC and 16.9% (10/59) in EC. Twenty-six women underwent OTC, and gynecologic cancer was the most common indication (9/26, 34.6%). One woman had the cryopreserved ovarian tissue retransplanted and successfully generated embryos. Conclusion: OC, EC, and OTC are possible options for preserving fertility, and these opportunities should be provided for women at risk of fertility decline or those who are eager to protect their future fertility. This is the first report on long-term FP outcomes in a single tertiary center in Korea. We expect that there will be more cases over the years and more women returning to use their gametes or embryos for pregnancy.

Interaction Mediator Assisted Synthesis of Mesoporous Molybdenum Carbide: Mo-Valence State Adjustment for Optimizing Hydrogen Evolution.

To overcome inherent limitations of molybdenum carbide (MoxC) for hydrogen evolution reaction (HER), i.e., low density of active site and nonideal hydrogen binding strength, we report the synthesis of valence-controlled mesoporous MoxC as a highly efficient HER electrocatalyst. The synthesis procedure uses an interaction mediator (IM), which significantly increases the density of active site by mediating interaction between PEO-b-PS template and Mo source. The valence state of Mo is tuned by systematic control of the environment around Mo by controlled heat treatment under air before thermal treatment at 1100 °C. Theoretical calculations reveal that the hydrogen binding is strongly influenced by Mo valence. Consequently, MoxC achieves a significant increase in HER activity (exceeding that of Pt/C at high current density ∼35 mA/cm2 in alkaline solution). In addition, a volcano-type correlation between HER activity and Mo valence is identified with various experimental indicators. The present strategies can be applied to various carbide and Mo-based catalysts, and the established Mo valence and HER relations can guide development of highly active HER electrocatalysts.

Enhancing Durability and Photoelectrochemical Performance of the Earth Abundant Ni-Mo/TiO2 /CdS/CIGS Photocathode under Various pH Conditions.

Cu(In,Ga)(S,Se)2 (CIGS) is a promising photocathode material owing to its high absorption coefficient, adjustable band gap, and suitable band edge for the hydrogen evolution reaction (HER). However, most CIGS photocathodes have suffered from instability in applications that require a wide range of pH conditions and have utilized noble metal HER catalysts to achieve a high performance. Thus, improving the durability of the CIGS photocathode under various pH conditions and developing a cost-effective non-noble metal catalyst are critical issues in the photoelectrochemical (PEC) application of this promising photocathode material. Here, we catalyze the CIGS photocathode with Ni-Mo as a non-noble metal to enhance the PEC efficiency, and we employ atomically grown TiO2 to passivate the CdS/CIGS surface and improve the stability under a wide range of pH conditions. Our Ni-Mo alloy exhibits the best HER catalytic activity among reported earth-abundant HER catalysts in both acidic and alkaline solutions. The Ni-Mo/CdS/CIGS photocathode yields an onset potential of 0.5 V (vs. RHE) and a short-circuit photocurrent density as high as 15-25 mA cm-2 under various pH conditions ranging from 0.4 to 14, which is highly comparable to that of Pt/CdS/CIGS. Furthermore, the passivation of CdS/CIGS with a thin TiO2 layer, obtained by atomic layer deposition, effectively prevents the photocorrosion of CdS and the dissolution of the Mo back contact, which are the main causes of the degradation of the photocathode. The optimized Ni-Mo/TiO2 /CdS/CIGS photocathode produces a stable photocurrent density at 0 VRHE for 100 minutes except under strong alkaline conditions. The current work presents a very useful method to improve the efficiency and durability of the CIGS photocathodes with an earth-abundant metal catalyst, which completely replaces Pt.

Association of low aerobic fitness with hyperfiltration and albuminuria in men.

PURPOSE: The purpose of this study was to evaluate the association of low aerobic fitness (AF), a quantitative phenotype primarily modified by physical activity, with the earlier markers of chronic kidney disease (CKD). METHODS: Maximum oxygen uptake (VO2max), the best index of AF, was estimated in an apparently healthy population of 34,769 adults without known history of diabetes and/or hypertension, and its association with renal function and albuminuria was analyzed retrospectively. VO2max was estimated using a cycle ergometer. Glomerular filtration rate was estimated with the Modification of Diet in Renal Disease Study equation. Glomerular hyperfiltration was defined as estimated glomerular filtration rate above the age- and sex-specific 97.5th percentile. Albuminuria was detected with dipstick urinalysis on fast morning urine and defined as ≥1+. RESULTS: VO2max levels were negatively correlated with the odds ratios of glomerular hyperfiltration in men (Ptrend = 0.039), not in women. VO2max was associated with glomerular hyperfiltration in young men (≤ the median age; Ptrend < 0.001), but not in old men. VO2max levels were negatively correlated with the odds ratio of albuminuria in men (Ptrend < 0.001), but not in women. These findings suggest that low AF may be associated with earlier markers of CKD in men. This association was not observed in women. CONCLUSION: From the results of this study, it can be concluded that low AF may be a possible independent, modifiable risk factor for CKD in men.