Girls typically show much lower suicide rates than boys in most OECD countries. However, in South Korea, the suicide rate of girls almost reaches that of boys. Moreover, Korean girls’ suicide rate is ...remarkable even among other advanced countries. One potential approach to explaining Korean girls’ relatively high suicide rate is to investigate how their peer groups affect suicidal ideation, but this approach has rarely been explored in Korean adolescents. We tested how the gender heterogeneity of peer groups is associated with suicidal ideation by analyzing 2,990 adolescents from the 2018 Korean Children and Youth Well-Being Index Survey. For the analysis, logistic regression models with survey weights were used. The analysis revealed that adolescents with different-gender friends were associated with a higher likelihood of suicidal ideation than those with exclusively same-gender friends when adjusting for covariates. In addition, an analysis stratified by gender found that this association was significant only among girls. Furthermore, the protective power of having a mentor against suicidal ideation was significantly lower in girls with male and female friends than in girls with only female friends. The findings suggest a less protective role of different-gender peer groups for suicidal ideation among girls. During adolescent suicidality consultations, school counselors and practitioners should pay attention to the characteristics of adolescents’ peers, particularly their gender.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Given a well-known overlapping prevalence of social isolation with loneliness and depression among older adults, this study aimed to contextually investigate the relationship of these constructs with ...weight loss of more than 5kg in a year, with a special focus on the intersection of living alone and marital dissolution as key dimensions of isolation. The data were obtained from the Korean Longitudinal Study of Aging (KLoSA) from 2006, 2008, 2010, 2012, 2014, 2016, and 2018, with an adult sample of those aged 65 and older (n = 5,481). The study evaluated several critical dimensions of social isolation: living alone, transition to living alone, infrequent social contact with children or friends, and infrequent social participation. These dimensions were examined individually and as a composite scale, along with loneliness and depressive symptoms, to determine their association with weight loss of 5kg or greater among older men and women. Generalized Estimating Equation (GEE) regression models enabled investigation of whether socially isolated men and women tended to lose 5kg or more in weight, given other confounding factors. Surprisingly, the results showed no evidence of such a trend. However, significant associations were found between weight loss and changes in living alone and marital status. For older men, transitioning to living alone without a change in marital status was linked to significant weight loss. For older women, transitioning to living alone following widowhood or divorce was the risk factor. These relationships remained significant even after adjusting for depression and a wide range of covariates. Additional analysis testing a cumulative effect revealed that only depression was a risk factor for being underweight at the last observation. Therefore, to prevent a clinically risky extent of weight loss, health policies for older Koreans should focus on those who transition to living alone, especially due to spousal bereavement or divorce (among women) and separation from living with children (among men).
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
With the demand for high-energy-storage devices, the rechargeable metal-oxygen battery has attracted attention recently. Sodium-oxygen batteries have been regarded as the most promising candidates ...because of their lower-charge overpotential compared with that of lithium-oxygen system. However, conflicting observations with different discharge products have inhibited the understanding of precise reactions in the battery. Here we demonstrate that the competition between the electrochemical and chemical reactions in sodium-oxygen batteries leads to the dissolution and ionization of sodium superoxide, liberating superoxide anion and triggering the formation of sodium peroxide dihydrate (Na2O2·2H2O). On the formation of Na2O2·2H2O, the charge overpotential of sodium-oxygen cells significantly increases. This verification addresses the origin of conflicting discharge products and overpotentials observed in sodium-oxygen systems. Our proposed model provides guidelines to help direct the reactions in sodium-oxygen batteries to achieve high efficiency and rechargeability.
Abstract Objectives Previous studies have indicated that compared to older adults, younger older adults (e.g., baby boomers) are more susceptible to obesity, but their risk decreases as they age. ...However, there is a lack of research on how individuals experience sarcopenic obesity, which increases in later life and is a mortality risk factor. This study examined how younger cohorts of older Americans and their demographic traits are related to sarcopenic obesity. Methods Generalized estimating equations were used to analyze participants aged 65 years and older, stratified by sex using data from the 2006–2016 Health and Retirement Study, with survey weights (n = 2,896 men and n = 4,268 women). Results The findings indicate that the youngest cohort (born between 1948 and 1953) had greater odds of sarcopenic obesity than older cohorts (born before 1931). However, the youngest cohort did not have significantly different risks from those born between 1931 and 1947. Unexpectedly, the youngest cohort of older women living alone tended not to have sarcopenic obesity compared to the older cohorts living alone. These results remained significant even after adjusting for various covariates, including marital status, race, education level, wealth, and other factors. Discussion This paper contributes to the existing literature on population health and demographic change in 2 ways. First, the risk of sarcopenic obesity is higher among younger cohorts of older Americans relative to older cohorts (born before 1931). Second, living alone may not necessarily be considered a worse health condition, particularly for younger female cohorts.
Redox mediators (RMs) are considered an effective countermeasure to reduce the large polarization in lithium‐oxygen batteries. Nevertheless, achieving sufficient enhancement of the cyclability is ...limited by the trade‐offs of freely mobile RMs, which are beneficial for charge transport but also trigger the shuttling phenomenon. Here, we successfully decoupled the charge‐carrying redox property of RMs and shuttling phenomenon by anchoring the RMs in polymer form, where physical RM migration was replaced by charge transfer along polymer chains. Using PTMA (poly(2,2,6,6‐tetramethyl‐1‐piperidinyloxy‐4‐yl methacrylate)) as a polymer model system based on the well‐known RM tetramethylpiperidinyloxyl (TEMPO), it is demonstrated that PTMA can function as stationary RM, preserving the redox activity of TEMPO. The efficiency of RM‐mediated Li2O2 decomposition remains remarkably stable without the consumption of oxidized RMs or degradation of the lithium anode, resulting in an improved performance of the lithium‐oxygen cell.
The shuttling phenomenon is the most severe drawback of redox mediators (RMs) in lithium‐oxygen batteries, caused by the freely mobile nature of RMs. The shuttle effect was eliminated by anchoring RMs on the air electrode in form of a polymer. Successful prevention of the shuttle effect results in a remarkable improvement of the lithium‐oxygen cell‐performance.
Shedding new light on conventional batteries sometimes inspires a chemistry adoptable for rechargeable batteries. Recently, the primary lithium-sulfur dioxide battery, which offers a high energy ...density and long shelf-life, is successfully renewed as a promising rechargeable system exhibiting small polarization and good reversibility. Here, we demonstrate for the first time that reversible operation of the lithium-sulfur dioxide battery is also possible by exploiting conventional carbonate-based electrolytes. Theoretical and experimental studies reveal that the sulfur dioxide electrochemistry is highly stable in carbonate-based electrolytes, enabling the reversible formation of lithium dithionite. The use of the carbonate-based electrolyte leads to a remarkable enhancement of power and reversibility; furthermore, the optimized lithium-sulfur dioxide battery with catalysts achieves outstanding cycle stability for over 450 cycles with 0.2 V polarization. This study highlights the potential promise of lithium-sulfur dioxide chemistry along with the viability of conventional carbonate-based electrolytes in metal-gas rechargeable systems.
The discovery of a reliable electrolyte system remains one of the key challenges for the development of advanced lithium–oxygen batteries. To date, no single electrolyte is verified to be stable and ...compatible with both the cathode (e.g., oxygen radicals, lithium peroxide, etc.) and anode (lithium metal) for lithium–oxygen batteries. In this work, a novel liquid‐based Janus electrolyte system consisting of two different immiscible liquid phases is proposed and it is demonstrated that this system is remarkably effective in promoting the sustainable operation of redox‐mediated lithium–oxygen batteries. The liquid‐based Janus electrolyte is rationally designed by considering its compatibility with the lithium–oxygen cell environment, the solubility difference of target soluble species, and the mutual immiscibility of the two liquid phases. By combining spectral characterization, a phase‐separation experiment, and in situ observation of the electrochemical cell, it is revealed that the liquid‐based Janus electrolyte suppresses the migration of redox mediators from one liquid phase to the other, thereby preventing the detrimental shuttle effect. The enhanced stability of redox mediation leads to improved cycling performance of the cell. The various combinations possible for the liquid‐based Janus electrolyte open a new unexplored pathway for the design of advanced electrolyte systems for lithium–oxygen batteries.
Liquid‐based Janus electrolytes refer to the electrolyte systems consisting of two immiscible liquid electrolytes. Janus electrolytes enable simultaneous use of two different liquid electrolytes whose properties are customized for anode and cathode, respectively. As a representative application, it is demonstrated that a Janus electrolyte with two electrolytes having distinct solvating properties suppresses the shuttle effect of redox mediators in lithium–oxygen batteries.
The Li–O2 battery is capable of delivering the highest energy density among currently known battery chemistries and is thus regarded as one of the most promising candidates for emerging ...high-energy-density applications such as electric vehicles. Although much progress has been made in the past decade in understanding the reaction chemistry of this battery system, many issues must be resolved regarding the active components, including the air electrode and electrolyte, to overcome the presently insufficient cycle life. In this work, we demonstrate that the degradation kinetics of both the air electrode and electrolyte during cycles can be significantly retarded through control of the crystallinity of the carbon electrode, the most frequently used air electrode in current Li–O2 batteries. Using 13C-based air electrodes with various degrees of graphitic crystallinity and in situ differential electrochemical mass spectroscopy analysis, it is demonstrated that, as the crystallinity increases in the carbon, the CO2 evolution from the cell is significantly reduced, which leads to a 3-fold enhancement in the cyclic stability of the cell.
Li‐O2 batteries are promising next‐generation energy storage systems because of their exceptionally high energy density (≈3500 W h kg−1). However, to achieve stable operation, grand challenges remain ...to be resolved, such as preventing electrolyte decomposition and degradation of carbon, a commonly used air electrode in Li‐O2 batteries. In this work, using in situ differential electrochemical mass spectrometry, it is demonstrated that the application of a ZnO coating on the carbon electrode can effectively suppress side reactions occurring in the Li‐O2 battery. By probing the CO2 evolution during charging of 13C‐labeled air electrodes, the major sources of parasitic reactions are precisely identified, which further reveals that the ZnO coating retards the degradation of both the carbon electrode and electrolyte. The successful suppression of the degradation results in a higher oxygen efficiency, leading to enhanced stability for more than 100 cycles. Nevertheless, the degradation of the carbon electrode is not completely prevented by the coating, because the Li2O2 discharge product gradually grows at the interface between the ZnO and carbon, which eventually results in detachment of the ZnO particles from the electrode and subsequent deterioration of the performance. This finding implies that surface protection of the carbon electrode is a viable option to enhance the stability of Li‐O2 batteries; however, fundamental studies on the growth mechanism of the discharge product on the carbon surface are required along with more effective coating strategies.
The effect of the atomic layer deposition coating on the stability of the carbon cathode and electrolyte in Li‐O2 batteries is studied using isotope 13C carbon to distinguish side reactions from the electrolyte decomposition and carbon degradation. Degradation kinetics of both the air electrode and electrolyte during cycles can be significantly retarded by shielding defect sites of carbon cathode, which result in enhanced cycle stability.
PDF
