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1.
Artigo em Inglês | MEDLINE | ID: mdl-38605680

RESUMO

OBJECTIVES: Based on the "linked lives" tenant of the life course perspective, this longitudinal study aims to examine the actor and partner effects of social participation on cognitive function in older Chinese couples. METHODS: A total of 1,706 couples aged over 60 were included in the final analyses. Social participation was measured using two questions regarding types of activities and frequency. Cognitive function was measured using a combination of memory, orientation, visuoconstruction, attention, and calculation. The lagged-dependent APIM was used to model the dyadic associations between social participation and cognitive function. RESULTS: The time-averaged actor effects of both husbands' and wives' social participation on their own cognitive function were significant (p < .001 for both). The time-averaged partner effect of husbands' social participation on wives' cognitive function was significant (p < .001) but the reverse-the effect of wives' social participation on husbands' cognitive function-was not (p = .381). The time-specific actor and partner effects were not significant (p > .05 for all). DISCUSSION: Our findings indicate an asymmetrical pattern of actor-partner interdependence, where husbands' social participation may affect their wives' cognitive function on average, but wives' social participation does not affect their husbands' cognitive function. Clinical practitioners should invite both partners, especially husbands, to participate in social participation interventions to facilitate crossover benefits for wives. Moreover, policymakers should build more facilities to encourage older couples to engage in social activities to prevent cognitive decline.

2.
BMC Plant Biol ; 24(1): 224, 2024 Mar 27.
Artigo em Inglês | MEDLINE | ID: mdl-38539093

RESUMO

BACKGROUND: Drought severely limits sunflower production especially at the seedling stage. To investigate the response mechanism of sunflowers to drought stress, we utilized two genotypes of sunflower materials with different drought resistances as test materials. The physiological responses were investigated under well-watered (0 h) and drought-stressed conditions (24 h, 48 h, and 72 h). RESULTS: ANOVA revealed the greatest differences in physiological indices between 72 h of drought stress and 0 h of drought stress. Transcriptome analysis was performed after 72 h of drought stress. At 0 h, there were 7482 and 5627 differentially expressed genes (DEGs) in the leaves of K55 and K58, respectively, and 2150 and 2527 DEGs in the roots of K55 and K58, respectively. A total of 870 transcription factors (TFs) were identified among theDEGs, among which the high-abundance TF families included AP2/ERF, MYB, bHLH,and WRKY. Five modules were screened using weighted gene coexpressionnetwork analysis (WGCNA), three and two of which were positively and negatively, respectively, related to physiological traits. KEGG analysis revealedthat under drought stress, "photosynthesis", "carotenoid biosynthesis", "starch and sucrose metabolism", "ribosome", "carotenoid biosynthesis", "starch and sucrose metabolism", "protein phosphorylation" and "phytohormone signaling" are six important metabolic pathways involved in the response of sunflower to drought stress. Cytoscape software was used to visualize the three key modules, and the hub genes were screened. Finally, a total of 99 important candidate genes that may be associated with the drought response in sunflower plants were obtained, and the homology of these genes was compared with that in Arabidopsis thaliana. CONCLUSIONS: Taken together, our findings could lead to a better understanding of drought tolerance in sunflowers and facilitate the selection of drought-tolerant sunflower varieties.


Assuntos
Arabidopsis , Helianthus , Humanos , Transcriptoma , Helianthus/genética , Helianthus/metabolismo , Resistência à Seca , Perfilação da Expressão Gênica , Secas , Arabidopsis/genética , Amido/metabolismo , Carotenoides/metabolismo , Sacarose/metabolismo , Estresse Fisiológico/genética , Regulação da Expressão Gênica de Plantas
3.
Inorg Chem ; 63(11): 5076-5082, 2024 Mar 18.
Artigo em Inglês | MEDLINE | ID: mdl-38447153

RESUMO

Herein, two Laves intermetallic series, ZrCo1.75M0.25 and NbCo1.75M0.25 (M = Fe, Co, Ni, Ru, Rh, Pd, Os, Ir, and Pt), were synthesized, and their hydrogen evolution reaction (HER) activities were examined to reveal the influence of d electrons to the corresponding HER activities. Owing to the different electronegativity between Zr and Nb (χZr = 1.33; χNb = 1.60), Co and/or M elements receive more electrons in ZrCo1.75M0.25 than that of the Nb one. This leads to the overall weak H adsorption energy (ΔGHad) of ZrCo1.75M0.25 series compared to that of NbCo1.75M0.25 and rationalizes well the superior HER activity of the Rh member compared to that of the Pt one in the ZrCo1.75M0.25 series. Under industrial conditions (333 K, 6.0 M KOH), ZrCo1.75Rh0.25 only requires an overpotential of 110 mV to reach the current density of 500 mA/cm2 and can be operated at high current density over 400 h. This work demonstrates that with a proper combination between elements in intermetallic phases, one can manipulate d electrons of the active metal to be closer to the sweet spot (ΔGHad = 0). The Pt member may no longer exhibit the best HER activity in series, and all elements exhibit the potential to outperform the Pt member in the HER with careful control of the d electron population.

4.
Ecol Evol ; 14(2): e11063, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-38380067

RESUMO

Egg recognition and rejection are the most common and effective anti-parasitic strategies against avian brood parasitism in terms of maintaining stability over time and plasticity in response to environmental cues. Conversely, parasites have evolved multiple counter-adaptations to the anti-parasitic defenses of hosts. Among them, the crypsis hypothesis suggests that eggs that appear more cryptic in color and are closely matched to the environment are helping to counter the egg recognition strategy of the host. In this study, we investigated whether the egg recognition ability of Oriental reed warblers (Acrocephalus orientalis), a common host of common cuckoos (Cuculus canorus), changed during different reproductive stages by using model egg experiments. The effect of the crypsis hypothesis on the egg recognition ability of the hosts was also investigated by controlling the color contrast between the inside of the experimental nests and the model eggs. The results showed that the Oriental reed warbler retained strong egg recognition abilities, which were similar to the incubation stage (GLMMs: F 1,27 = 0.424, p = .521), even after entering the nestling stage and preferentially rejected model eggs with distinct contrasting colors (binomial test: Fisher's exact, p = .016). These results are consistent with the crypsis hypothesis. The present study suggests that the host retains a strong egg recognition ability even during the nestling stage and that cryptic-colored eggs that are closely matched with the breeding nest environment help counter the host's egg recognition abilities and increase the chances of successful parasitism by cuckoos. However, the effectiveness of cryptic egg may be weaker than mimic egg in countering egg recognition and rejection by hosts with open-cup nests.

5.
Adv Mater ; : e2312868, 2024 Jan 19.
Artigo em Inglês | MEDLINE | ID: mdl-38241728

RESUMO

The intelligent construction of non-noble metal materials that exhibit reversible oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) with bifunctional electrocatalytic performance is greatly coveted in the realm of zinc-air batteries (ZABs). Herein, a crafted structure-amorphous MnO2 lamellae encapsulated covalent triazine polymer-derived N, S, P co-doped carbon sphere (A-MnO2 /NSPC) is designed using a self-doped pyrolysis coupled with an in situ encapsulation strategy. The customized A-MnO2 /NSPC-2 demonstrates a superior bifunctional electrocatalytic performance, confirmed by a small ΔE index of 0.64 V for ORR/OER. Experimental investigations, along with density functional theory calculations validate that predesigned amorphous MnO2 surface defects and abundant heteroatom catalytic active sites collectively enhance the oxygen electrocatalytic performance. Impressively, the A-MnO2 /NSPC-based rechargeable liquid ZABs show a large open-circuit potential of 1.54 V, an ultrahigh peak power density of 181 mW cm-2 , an enormous capacity of 816 mAh g-1 , and a remarkable stability for more than 1720 discharging/charging cycles. Additionally, the assembled flexible all-solid-state ZABs also demonstrate outstanding cycle stability, surpassing 140 discharging/charging cycles. Therefore, this highly operable synthetic strategy offers substantial understanding in the development of magnificent bifunctional electrocatalysts for various sustainable energy conversions and beyond.

6.
Adv Sci (Weinh) ; : e2400364, 2024 Jan 22.
Artigo em Inglês | MEDLINE | ID: mdl-38251278

RESUMO

Sodium-ion batteries (SIBs) and sodium-ion capacitors (SICs) are promising candidates for cost-effective and large-scale energy storage devices. However, sluggish kinetics and low capacity of traditional anode materials inhibit their practical applications. Herein, a novel design featuring a layer-expanded MoS2 is presented that dual-reinforced by hollow N, P-codoped carbon as the inner supporter and surface groups abundant MXene as the outer supporter, resulting in a cross-linked robust composite (NPC@MoS2 /MXene). The hollow N, P-codoped carbon effectively prevents agglomeration of MoS2 layers and facilitates shorter distances between the electrolyte and electrode. The conductive MXene outer surface envelops the NPC@MoS2 units inside, creating interconnected channels that enable efficient charge transfer and diffusion, ensuring rapid kinetics and enhanced electrode utilization. It exhibits a high reversible capacity of 453 mAh g-1 , remarkable cycling stability, and exceptional rate capability with 54% capacity retention when the current density increases from 100 to 5000 mA g-1 toward SIBs. The kinetic mechanism studies reveal that the NPC@MoS2 /MXene demonstrates a pseudocapacitance dominated hybrid sodiation/desodiation process. Coupled with active carbon (AC), the NPC@MoS2 /MXene//AC SICs achieve both high energy density of 136 Wh kg-1 at 254 W kg-1 and high-power density of 5940 W kg-1 at 27 Wh g-1 , maintaining excellent stability.

7.
J Psychosom Res ; 176: 111563, 2024 01.
Artigo em Inglês | MEDLINE | ID: mdl-38103280

RESUMO

OBJECTIVE: Illness perceptions direct coping resources in the illness adaptation process. Previous studies regarding illness perception profiles have been conducted at the individual level, without considering the couple as a unit. This study aimed to investigate the dyadic topologies of illness perceptions in HIV-serodiscordant couples and the association between the identified profiles and individual- and couple-level outcomes. METHODS: A comprehensive examination was undertaken, encompassing 231 Chinese HIV-serodiscordant couples, who voluntarily participated in this cross-sectional study during the period spanning June to October 2022. To discern various patterns of illness perception, dyadic latent profile analyses were performed, followed by the implementation of one-way analyses of variance to investigate outcome differences at both the individual and couple levels across the identified profiles. RESULTS: We identified three distinct profiles of illness perception, namely the incongruent-but-low, congruent-but-high, and incongruent-and-high profiles. Except for the partner's sex (p < .01, Cramer' v = 0.214) and the education levels of persons living with HIV and their partners (both p < .01, Cramer' v = 0.236 for persons living with HIV and 0.198 for partners), no significant demographic differences across the various profiles were found. Furthermore, we observed significant differences in all outcomes among the different couple profiles (all p < .001). These differences were of medium-to-large magnitudes (partial η2 values ranging from 0.07 to 0.22). CONCLUSION: A couple-centered typological approach provides a useful way of identifying the couple's configuration of illness perceptions, which will inform the provision of tailor-made treatment for couples with different profiles.


Assuntos
Infecções por HIV , Parceiros Sexuais , Humanos , Estudos Transversais , HIV , População do Leste Asiático
8.
ACS Appl Mater Interfaces ; 16(1): 633-642, 2024 Jan 10.
Artigo em Inglês | MEDLINE | ID: mdl-38150331

RESUMO

It is highly desirable to fabricate transition bimetallic alloy-embedded porous nanocarbons with a unique nanoarchitecture for the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) in rechargeable zinc-air batteries. In this work, we introduce a template-assisted in situ alloying synthesis of FeNi alloy nanoparticle-decorated coral-like nanocarbons (FeNi-CNCs) as efficient OER/ORR dual-functional electrocatalysts. The present materials are produced through polycondensation of a covalent triazine framework (CTF), the coordination of Ni and Fe ions, and sequential pyrolytic treatment. Through the pyrolysis process, the nanolamellar FeNi-CTF precursors can be facilely converted into FeNi alloy nanoparticle-decorated nanocarbons. These nanocarbons possess a distinctive three-dimensional (3D) coral-like nanostructure, which is favorable for the transport of oxygen and the diffusion of electrolyte. As a result, FeNi-CNC-800 with the highest efficiency exhibited remarkable electrocatalytic performance and great durability. Additionally, it also can be assembled into rechargeable zinc-air batteries that can be assembled in both liquid and solid forms, offering a superior peak power density, large specific capacity, and outstanding reusability during charging/discharging cycles (e.g., 5160 charging-and-discharging cycles at 10 mA cm-2 for the liquid forms). These traits make it a highly promising option in the burgeoning field of wearable energy conversion.

9.
J Environ Sci (China) ; 138: 418-427, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38135407

RESUMO

Bi2O2CO3(BOC)/Bi4O5Br2(BOB)/reduced graphene oxide (rGO) Z-scheme heterojunction with promising photocatalytic properties was synthesized via a facile one-pot room-temperature method. Ultra-thin nanosheets of BOC and BOB were grown in situ on rGO. The formed 2D/2D direct Z-scheme heterojunction of BOC/BOB with oxygen vacancies (OVs) effectively leads to lower negative electron reduction potential of BOB as well as higher positive hole oxidation potential of BOC, showing improved reduction/oxidation ability. Particularly, rGO is an acceptor of the electrons from the conduction band of BOC. Its dual roles significantly improve the transfer performance of photo-induced charge carriers and accelerate their separation. With layered nanosheet structure, rich OVs, high specific surface area, and increased utilization efficiency of visible light, the multiple synergistic effects of BOC/BOB/rGO can achieve effective generation and separation of the electron-holes, thereby generating more •O2- and h+. The photocatalytic reduction efficiency of CO2 to CO (12.91 µmol/(g·hr)) is three times higher than that of BOC (4.18 µmol/(g·hr)). Moreover, it also achieved almost 100% removal of Rhodamine B and cyanobacterial cells within 2 hours.


Assuntos
Elétrons , Grafite , Temperatura , Oxigênio
10.
Phys Chem Chem Phys ; 25(42): 29182-29191, 2023 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-37870596

RESUMO

In recent years, two-dimensional materials have aroused enormous interest owing to their superior electrochemical performance, abundant exposed active sites, high specific surfaces and so on. Unlike many stable allotropes, honeycomb hexagonal borophene is kinetically unstable. In this study, we introduce transition metal atoms (Cr, Fe and Co) to stabilize honeycomb hexagonal borophene, forming stable graphene-like TMB6 (TM = Cr, Fe and Co) monolayers. Moreover, we explored the possibility of superconductivity and the anchoring materials of lithium-sulfur batteries using the first-principles density functional theory (DFT) calculation. Our results show that CoB6 exhibited the best superconductivity with a superconducting transition temperature of 33.3 K. Furthermore, CoB6 and FeB6 are promising anchoring materials because of the suppression of lithium polysulfides shuttling in lithium-sulfur batteries because they can accelerate sulfur reduction reaction kinetics.

11.
J Mol Model ; 29(10): 314, 2023 Sep 14.
Artigo em Inglês | MEDLINE | ID: mdl-37707644

RESUMO

CONTEXT: The adsorptions of toxic gases SO2 and H2S on 2D α/ß/γ-FeB6 monolayer were investigated using density functional theory calculations. To analyze the interaction between gas molecule H2S/SO2 and α/ß/γ-FeB6 monolayer, we calculated adsorption energy, adsorption distance, Mullikan charge, charge density difference, band structure, the density of states, work function, and theoretical recovery time. The adsorption energies show that H2S/SO2 is chemisorbed on α/ß-FeB6 while H2S/SO2 is physiosorbed on γ-FeB6 monolayer. As a result, γ-FeB6 has a short recovery time for H2S (5.71×10-8 s)/SO2 (1.94×10-5 s) due to modest adsorption. Therefore, γ-FeB6 may be a promising candidate for reusable H2S/SO2 sensors at room temperature. Although H2S is chemisorbed on α/ß-FeB6, as the working temperature rises to 500 K, the recovery time of α/ß-FeB6 for H2S can decrease to 1.13×10-1 s and 2.08×10-1 s, respectively, which are well within the detectable range. So, α/ß-FeB6 monolayer also may be a good candidate for H2S gas sensor. METHODS: Calculations were performed at GGA-PBE/DNP level using the Dmol3 module implemented in the Material Studio 2018 software package.

12.
Ann Behav Med ; 57(11): 978-987, 2023 Oct 16.
Artigo em Inglês | MEDLINE | ID: mdl-37435876

RESUMO

BACKGROUND: Since HIV has evolved into a lifelong but manageable condition, improving the quality of life (QoL) of persons living with HIV (PLWHs) has become increasingly important. Living with HIV is life-altering and poses substantial challenges for both PLWHs and their partners, so identifying how HIV serodiscordant couples cope with HIV together is crucial. Here, Bodenmann's Systemic Transaction Model highlights common dyadic coping (CDC), which refers to both partners working together to alleviate the negative effects of stress. PURPOSE: We examined the mediating role of CDC in linking we-disease appraisal with relationship satisfaction and QoL. METHODS: We recruited a convenience sample of 231 HIV serodiscordant couples via local grassroots organizations between June and October 2022. Participants completed measures of we-disease appraisal, CDC, relationship satisfaction, and QoL. We examined the mediation effect of CDC on the association between we-disease appraisal and outcomes using the common fate mediation model. RESULTS: The mean age of PLWHs was 32.18 years (standard deviation = 8.61 years), and that of their partners was 32.55 years (standard deviation = 9.24 years). The average time since HIV diagnosis was 4.18 years. Most couples were same-sex male couples. We found that CDC mediated the effect of we-disease appraisal on relationship satisfaction. Moreover, CDC significantly mediated the effect of we-disease appraisal on the QoL of PLWHs and their partners. CONCLUSIONS: Our findings highlight the importance of CDC in dyadic illness management among Chinese HIV serodiscordant couples.


Numerous studies have shown that HIV serodiscordant couples may face HIV-related stress as a unit. Yet, it is not clear how the appraisal of HIV as a shared illness (i.e., we-disease appraisal) may influence relationship satisfaction and both partners' quality of life (QoL) via common dyadic coping (CDC) behaviors (e.g., collaboration). In this study, we collected data from 231 HIV serodiscordant couples. Participants completed reports of how they appraise HIV as a we-disease, their CDC behaviors, and their relationship satisfaction and QoL. We found that we-disease appraisal was positively associated with CDC, which in turn was positively associated with relationship satisfaction and both partners' QoL. Future couple-based interventions should incorporate psycho-educational components to raise awareness about we-disease appraisal, as well as skill-building components to encourage the use of CDC in clinical settings.

13.
ACS Nano ; 17(13): 12278-12289, 2023 Jul 11.
Artigo em Inglês | MEDLINE | ID: mdl-37377176

RESUMO

A catalyst kinetics optimization strategy based on tuning active site intermediates adsorption is proposed. Construction of the M-OOH on the catalytic site before the rate-determining step (RDS) is considered a central issue in the strategy, which can optimize the overall catalytic kinetics by avoiding competition from other reaction intermediates on the active site. Herein, the kinetic energy barrier of the O-O coupling for as-prepared sulfated Co-NiFe-LDH nanosheets is significantly reduced, resulting in the formation of M-OOH on the active site at low overpotential, which is directly confirmed by in situ Raman and charge transfer fitting results. Moreover, catalysts constructed from active sites of highly efficient intermediates make a reliable model for studying the mechanism of the OER in proton transfer restriction. In weakly alkaline environments, a sequential proton-electron transfer (SPET) mechanism replaces the concerted proton-electron transfer (CPET) mechanism, and the proton transfer step becomes the RDS; high-speed consumption of reaction intermediates (M-OOH) induces sulfated Co-NiFe-LDH to exhibit excellent kinetics.

14.
Small Methods ; 7(9): e2300050, 2023 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-37144659

RESUMO

An electrical-biased or mechanical-loaded scanning probe written on the ferroelectric surface can generate programmable domain nanopatterns for ultra-scaled and reconfigurable nanoscale electronics. Fabricating ferroelectric domain patterns by direct-writing as quickly as possible is highly desirable for high response rate devices. Using monolayer α-In2 Se3 ferroelectric with ≈1.2 nm thickness and intrinsic out-of-plane polarization as an example, a writing-speed dependent effect on ferroelectric domain switching is discovered. The results indicate that the threshold voltages and threshold forces for domain switching can be increased from -4.2 to -5 V and from 365 to 1216 nN, respectively, as the writing-speed increases from 2.2 to 10.6 µm s-1 . The writing-speed dependent threshold voltages can be attributed to the nucleations of reoriented ferroelectric domains, in which sufficient time is needed for subsequent domain growth. The writing-speed dependent threshold forces can be attributed to the flexoelectric effect. Furthermore, the electrical-mechanical coupling can be employed to decrease the threshold force, achieving as low as ≈189±41 nN, a value smaller than those of perovskite ferroelectric films. Such findings reveal a critical issue of ferroelectric domain pattern engineering that should be carefully addressed for programmable direct-writing electronics applications.

15.
PeerJ ; 11: e15275, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37159834

RESUMO

Sunflower is an important oilseed crop across the world. It is considered as a moderately drought tolerant plant, however, its yield is still negatively affected by drought stress. Improving drought tolerance is of the outmost important for breeding. Although several studies have documented the relationship between the sunflower phenotype and genotype under drought stress, but relatively few studies have simultaneously investigated the molecular mechanisms of drought tolerance in the sunflower at different growth stages. In this study, we conducted quantitative trait locus (QTL) analysis for different sunflower traits during the germination and seedling stages. Eighteen phenotypic traits were evaluated under well-watered and drought stress conditions. We determined that the germination rate, germination potential, germination index, and root-to-shoot ratio can be used as effective indexes for drought tolerance selection and breeding. A total of 33 QTLs were identified on eight chromosomes (PVE: 0.016%-10.712% with LOD: 2.017-7.439). Within the confidence interval of the QTL, we identified 60 putative drought-related genes. Four genes located on chromosome 13 may function in both germination and seedling stages for drought response. Genes LOC110898128, LOC110898092, LOC110898071, and LOC110898072 were annotated as aquaporin SIP1-2-like, cytochrome P450 94C1, GABA transporter 1-like, and GABA transporter 1-like isoform X2, respectively. These genes will be used for further functional validation. This study provides insight into the molecular mechanisms of the sunflower's in response to drought stress. At the same time, it lays a foundation for sunflower drought tolerance breeding and genetic improvement.


Assuntos
Asteraceae , Helianthus , Helianthus/genética , Plântula/genética , Germinação/genética , Secas , Proteínas da Membrana Plasmática de Transporte de GABA , Melhoramento Vegetal , Aquaporina 2
17.
Small ; 19(32): e2208211, 2023 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-37078912

RESUMO

Nowadays, the exploration of electromagnetic (EM) wave absorbers with anticorrosion to improve the survivability and environmental adaptability of military targets in the harsh environments is becoming an attractive and unavoidable challenge. Herein, through modulation of the metal composition in the precursors, the core@shell structure Prussian blue analog-derived NiCo@C, CoFe@C, NiFe@C, and NiCoFe@C are obtained with excellent EM wave absorption performance. As for NiCoFe@C, ascribed to the coupling effect of the dual magnetic alloy, a minimum reflection loss (RL) of -47.6 dB and an effective absorption bandwidthof 5.83 GHz are realized, which cover the whole Ku-band. Meanwhile, four absorbers display the lower corrosion current density (10-4 -10-6 A cm-2 ) and larger polarization resistance (104 -106  Ω) under acid, neutral, and alkaline corrosion conditions over uninterrupted 30 days. Furthermore, due to the spatial barrier effect and the passivation effect of the graphitic carbon shell , the continuous salt spray test has little effect on RL performance and inconspicuously changes the surface morphologies of coating, demonstrating its excellent bifunctional performance. This work lays the foundation for the development of metal-organic frameworks-derived materials with both anticorrosion and EM wave absorption performance.

18.
Polymers (Basel) ; 15(6)2023 Mar 17.
Artigo em Inglês | MEDLINE | ID: mdl-36987279

RESUMO

With the increasing demand for plastic components, the development of lightweight, high strength and functionalized polypropylene (PP) from a cost-effective and environmentally friendly process is critical for resource conservation. In situ fibrillation (INF) and supercritical CO2 (scCO2) foaming technology were combined in this work to fabricate PP foams. Polyethylene terephthalate (PET) and poly(diaryloxyphosphazene)(PDPP) particles were applied to fabricate in situ fibrillated PP/PET/PDPP composite foams with enhanced mechanical properties and favorable flame-retardant performance. The existence of PET nanofibrils with a diameter of 270 nm were uniformly dispersed in PP matrix and served multiple roles by tuning melt viscoelasticity for improving microcellular foaming behavior, enhancing crystallization of PP matrix and contributing to improving the uniformity of PDPP's dispersion in INF composite. Compared to pure PP foam, PP/PET(F)/PDPP foam exhibited refined cellular structures, thus the cell size of PP/PET(F)/PDPP foam was decreased from 69 to 23 µm, and the cell density increased from 5.4 × 106 to 1.8 × 108 cells/cm3. Furthermore, PP/PET(F)/PDPP foam showed remarkable mechanical properties, including a 975% increase in compressive stress, which was attributed to the physical entangled PET nanofibrils and refined cellular structure. Moreover, the presence of PET nanofibrils also improved the intrinsic flame-retardant nature of PDPP. The synergistical effect of the PET nanofibrillar network and low loading of PDPP additives inhibited the combustion process. These gathered advantages of PP/PET(F)/PDPP foam make it promising for lightweight, strong, and fire-retardant polymeric foams.

19.
Small ; 19(28): e2301075, 2023 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-36978240

RESUMO

Defect chemistry in carbon matrix shows great potential for promoting the oxygen reduction reaction (ORR) of metal single-atom catalysts. Herein, a modified pyrolysis strategy is proposed to tune carbon defects in copper single-atom catalysts (Cu-SACs) to fully understand their positive effect on the ORR activity. The optimized Cu-SACs with controllable carbon defect degree and enhanced active specific surface area can exhibit improved ORR activity with a half-wave potential of 0.897 VRHE , ultrahigh limiting current density of 6.5 mA cm-2 , and superior turnover frequency of 2.23 e site-1 s-1 . The assembled Zn-air batteries based on Cu-SACs can also show well-retained reversibility and voltage platform over 1100 h charge/discharge period. Density functional theory calculations reveal that suitable carbon defects can redistribute charge density of Cu-N4 active sites to weaken the O-O bond in adsorbed OOH* intermediate and thus reduce its dissociation energy. This discovery offers a universal strategy for fabricating superior single-atom catalysts with high-efficiency active sites toward energy-directed applications.

20.
Artigo em Inglês | MEDLINE | ID: mdl-36834037

RESUMO

Synthesizing evidence to examine changes in suicide-related outcomes before and during the pandemic can inform suicide management during the COVID-19 crisis. We searched 13 databases as of December 2022 for studies reporting both the pre- and peri-pandemic prevalence of suicidal ideation, suicide attempts, or rate of death by suicide. A random-effects model was used to pool the ratio of peri- and pre-pandemic prevalence of suicidal ideation and attempt (Prevalence Ratio-PR) and rate of death by suicide (Rate Ratio; RR). We identified 51, 55, and 25 samples for suicidal ideation, attempt, and death by suicide. The prevalence of suicidal ideation increased significantly among non-clinical (PR = 1.142; 95% CI: 1.018-1.282; p = 0.024; k = 28) and clinical (PR = 1.134; 95% CI: 1.048-1.227; p = 0.002; k = 23) samples, and pooled estimates differed by population and study design. Suicide attempts were more prevalent during the pandemic among non-clinical (PR = 1.14; 95% CI: 1.053-1.233; p = 0.001; k = 30) and clinical (PR = 1.32; 95% CI: 1.17-1.489; p = 0.000; k = 25) participants. The pooled RR for death by suicide was 0.923 (95% CI: 0.84-1.01; p = 0.092; k = 25), indicating a nonsignificant downward trend. An upward trend of suicidal ideation and suicide attempts was observed during the COVID-19 pandemic, despite suicide rate remaining stable. Our findings suggest that timely prevention and intervention programs are highly needed for non-clinical adult population and clinical patients. Monitoring the real-time and long-run suicide risk as the pandemic evolves is warranted.


Assuntos
COVID-19 , Pandemias , Adulto , Humanos , Tentativa de Suicídio , Ideação Suicida , Prevalência
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