Worker Lifespan Research Articles

Comparative assessment of food consumption, longevity, thermoregulation, and molecular health markers in mite-resistant and Italian honey bee stocks

Identifying traits for adaptation to different management and environmental regimes is key to maintaining robust honey bee populations under global climate change. We compared mite-resistant (Pol-line and Russian) and Italian honey bee stocks in variable-temperature cage experiments (200 bees per cage) with respect to food consumption, thermoregulation, gene expression, and lifespan, in 3 experiments over 2 years. The Italian stock bees consumed more syrup and pollen on average than the mite-resistant stocks, but the mite-resistant stocks maintained higher cluster temperatures and had median lifespans 8 days longer, consistent with the increased expression of vitellogenin relative to Italian stock. Model results indicated that, to maintain the same colony size as the mite-resistant stocks, Italian stock colonies would need about 13% more sealed brood to offset reduced worker lifespans. These differences among bee stocks likely influence colony-level productivity and health, and showed the importance of experimental replication.

Ladderlike polysilsesquioxanes derived dual-carbon-buffer-shell structural silicon as stable anode materials for lithium-ion batteries

Silicon-carbon (Si/C) composite materials have been proven to be one of the most promising anode materials for the next generation of lithium-ion batteries (LIBs) due to their high theoretical capacity. However, the substantial volume changes during alloying/dealloying processes have posed significant challenges to the working lifespan of Si-based anodes. In this study, we designed a dual-carbon-layer-structured Si composite anode material (DCS-Si). Using ladderlike polysilsesquioxanes as a precursor, we employed a zinc thermal reaction to internally reduce the Si–O–Si framework to Si0. Simultaneously, the phenyl groups directly connected to Si atoms served as a carbon source for the internally dense coating layer. The obtained product underwent further coating controllable pyrolysis reactions to form an external carbon coating layer. As anode for LIBs, DCS-Si delivered a reversible specific capacity exceeding 1000 mAh g−1. Even after 1350 cycles at a current density of 0.3 A g−1, the specific capacity remained above 500 mAh g−1. Moreover, even under a high current density of 3 A g−1, after nearly 1000 cycles, the capacity retention rate still exceeded 70%. Further testing of the full cell also indicated that DCS-Si is a highly promising high-energy-density anode, with potential applications in future commercial lithium-ion batteries.

Synergistic negative effects between a fungicide and high temperatures on homing behaviours in honeybees.

Interactions between environmental stressors may contribute to ongoing pollinator declines, but have not been extensively studied. Here, we examined the interaction between the agricultural fungicide Pristine (active ingredients: 25.2% boscalid, 12.8% pyraclostrobin) and high temperatures on critical honeybee behaviours. We have previously shown that consumption of field-realistic levels of this fungicide shortens worker lifespan in the field and impairs associative learning performance in a laboratory-based assay. We hypothesized that Pristine would also impair homing and foraging behaviours in the field, and that an interaction with hot weather would exacerbate this effect. Both field-relevant Pristine exposure and higher air temperatures reduced the probability of successful return on their own. Together, the two factors synergistically reduced the probability of return and increased the time required for bees to return to the hive. Pristine did not affect the masses of pollen or volumes of nectar or water brought back to the hive by foragers, and it did not affect the ratio of forager types in a colony. However, Pristine-fed bees brought more concentrated nectar back to the hive. As both agrochemical usage and heat waves increase, additive and synergistic negative effects may pose major threats to pollinators and sustainable agriculture.

Effects of ingested essential oils and propolis extracts on honey bee (Hymenoptera: Apidae) health and gut microbiota.

Managed honey bee (Hymenoptera: Apidae: Apis mellifera Linnaeus) hives require frequent human inputs to maintain colony health and productivity. A variety of plant natural products (PNPs) are delivered via feeding to control diseases and reduce the use of synthetic chemical treatments. However, despite their prevalent use in beekeeping, there is limited information regarding the impact of ingested PNPs on bee health. Here, we tested the effects of different essential oils and propolis extracts on honey bee life span, nutrient assimilation, xenobiotic detoxification, and gut microbiota abundance. Brazilian propolis extract lengthened worker life span, while the other PNPs (Louisiana propolis extract, lemongrass oil, spearmint oil, and thyme oil) exerted variable and dose-dependent effects on life span. Vitellogenin (vg) gene expression was reduced by Brazilian propolis extract at high doses. Expression of CYP6AS1, a detoxification-related gene, was reduced by low doses of thyme oil. The abundances of 8 core gut microbiota taxa were largely unaffected by host consumption of PNPs. Our results suggest that in addition to propolis's structural and immunomodulatory roles in the colony, it may also exert beneficial health effects when ingested. Thyme oil, a commonly used hive treatment, was toxic at field-realistic dosages, and its use as a feed additive should be viewed with caution until its effects on bee health are more thoroughly investigated. We conclude that the tested propolis extracts, lemongrass oil, and spearmint oil are generally safe for bee consumption, with some apparent health-promoting effects.

Performance and analysis of sputtered silicon nitride cutting inserts in CNC machining

In this automated world, the role of machine tools such as cutting inserts and drills required for any type of work piece plays an important role in producing precision outputs. As technology improved, the manufacture of Components is mostly automatic in all type of manufacturing industries. The different measurements for a given component are generated with CAD software and then transformed into a finished component with CAM software. CNC machines are used in industries to cut metal components with extreme precision for any hardware goods. Automobile parts, aero parts and polymer consumer components are the most often produced things by these machines. Since these machines have certain specifications, CNC machines frequently use additional tools and parts which includes cutting inserts. So, in this automated environment, these cutting inserts quality has to be ensured for maintaining the precision measurements. A wide known fact is that insert tool failure occurs due to tool wear. When comparing with uncoated Silicon nitride insert, the working life span of coated insert can also be increased. Hence for this reason, DC magnetron technique is proposed to ensure quality and also to increase life of cutting tool by improving its hardness and wear resistance by coating a thin film of tungsten carbide in cutting tool insert. For this reason, the hardest material Tungsten carbide is coated over the Silicon Nitride tool insert. The coated insert has to be tested for its microstructure, surface hardness and grain distribution. Later, bonding efficiency and surface hardness test has to be carried out through Nano indentation and scratch test process.

A Systematic Analysis of Biological, Sociodemographic, Psychosocial, and Lifestyle Factors Contributing to Work Ability Across the Working Life Span: Cross-sectional Study

As employees age, their physical and mental abilities decline and work ability decreases, enhancing the risk for long-term sick leave or even premature retirement. However, the relative impact of biological and environmental determinants on work ability with increasing age is poorly understood in terms of their complexity. Previous research has shown relationships between work ability and job and individual resources, as well as specific demographic and lifestyle-related variables. However, other potentially important predictors of work ability remain unexplored, such as personality traits and biological determinants, including cardiovascular, metabolic, immunological, and cognitive abilities or psychosocial factors. Our aim was to systematically evaluate a wide range of factors to extract the most crucial predictors of low and high work ability across the working life span. As part of the Dortmund Vital Study, 494 participants from different occupational sectors, aged between 20 and 69 years, completed the Work Ability Index (WAI) assessing employee's mental and physical resources. A total of 30 sociodemographic variables were grouped into 4 categories (social relationships, nutrition and stimulants, education and lifestyle, and work related), and 80 biological and environmental variables were grouped into 8 domains (anthropometric, cardiovascular, metabolic, immunologic, personality, cognitive, stress related, and quality of life) and have been related to the WAI. Using the analyses, we extracted important sociodemographic factors influencing work ability, such as education, social activities, or sleep quality, and identified age-dependent and age-independent determinants of work ability. Regression models explained up to 52% of the WAI variance. Negative predictors of work ability were chronological and immunological age, immunological inefficiency, BMI, neuroticism, psychosocial stress, emotional exhaustion, demands from work, daily cognitive failures, subclinical depression, and burnout symptoms. Positive predictors were maximum heart rate during ergometry, normal blood pressure, hemoglobin and monocyte concentration, weekly physical activity, commitment to the company, pressure to succeed, and good quality of life. The identified biological and environmental risk factors allowed us to evaluate work ability in its complexity. Policy makers, employers, and occupational safety and health personnel should consider the modifiable risk factors we identified to promote healthy aging at work through focused physical, dietary, cognitive, and stress-reduced preventive programs, in addition to well-balanced working conditions. This may also increase the quality of life, commitment to the job, and motivation to succeed, which are important factors to maintain or even enhance work ability in the aging workforce and to prevent early retirement. ClinicalTrials.gov NCT05155397; https://clinicaltrials.gov/ct2/show/NCT05155397. RR2-10.2196/32352.

Дозазависимое влияние 20-гидроксиэкдизона и левзейного мёда на продолжительность жизни медоносных пчёл в условиях гипертермии

A study was conducted on 20-hydroxyecdysone at a concentration of 10-10 mol/l to 10-7 mol/l, fed in sugar syrup on the lifespan of workers under conditions of hyperthermia (50 °C). The study was carried out both in summer and during wintering. Low concentrations of 20E up to 0.4×10-9 mol/l inclusive promoted the increase in resistance to hyperthermia, which, when increased to 2×10-9, sharply drops by 1.8 times and rises again at a concentration of 1×10-7 mol/l. It has been suggested that when exogenous 20E was supplied with food at a concentration of 2×10-9 mol/l, the enzymatic oxidation of 20E was activated, which causes a decrease in the level of endogenous 20E titer in the hemolymph and change in the sign of the effect. The change of bees survival time under hyperthermia with half-maximal effective concentration (EC50) of 20E 1×10-9 mol/l can be used as a method for determining the content of 20E. In this way it is determined that the Leuzea honey sample contains 2×10-5 mol/kg (10 mg/kg) 20E. The content of 20Е in Leuzea honey sample determined in this way was 2×10-5 mol/kg (10 mg/kg).

Biomaterials for artificial knee joint replacement: a review

Human knee works under lubrication conditions that are characterised as boundary or mixed lubrication. In these situations, the joint suffers from starved lubrication provided by the synovial fluid. Over an extended period of time, this starved lubrication causes excessive wear and leads to osteoarthritis. Biomedical implants are gaining increasing attention nowadays to improve the working lifespan of artificial implants like hip and knee joints. This stems from the fact that friction and wear are the key factors affecting the life of artificial joints. In this review, we discuss the processes affecting the normal functioning of the joint. In this model, we also discuss the materials used for the orthopaedic industry and the problems which lead to the failure of the same. The possibilities of improving the life span of ultra-high molecular weight polyethylene (UHMWPE) are also discussed as UHMWPE is the gold in the orthopaedic industry.

Simulation Study of the Swirl Spray Atomization of a Bipropellant Thruster under Low Temperature Conditions

The spray atomization of an injector significantly influences the performance and working life span of a bipropellant thruster of a spacecraft. Deep space exploration requires the thruster to be able to operate reliably at a low temperature range from −40 °C to 0 °C, so the effect of low temperature conditions on the atomization characteristics of injector spray is motivated to be comprehensively investigated. To study the swirl atomization characteristics of MMH (methylhydrazine), which is more difficult to atomize than NTO (nitrogen tetroxide), numerical simulations were conducted, employing the methods of VOF (volume of fluid) and LES (large eddy simulation) under low temperature conditions. The physical model with a nozzle size of 0.5 mm and boundary conditions with a velocity inlet of 3.89 m/s both follow the actual operation of thrusters. The development of spray atomization at low temperatures was observed through parametric comparisons, such as spray velocity, liquid total surface area, droplet particle size distribution, spray cone angle and breakup distance. When the temperature decreased from 20 °C to −40 °C at the same condition of flowrate inlet, those atomization characteristics of MMH propellant vary following these rules: the spray ejection velocity of MMH is significantly reduced by 7.7%, and gas-liquid disturbance sequentially decreases; the liquid film development is more stable, with a negative influence on atomization quality, causing difficulties for primary and secondary breakup, so the total surface area of droplets also decreases by 6.4%; the spatial distribution characteristics, spray cone angle and breakup distance vary less than 5%. Therefore, the low temperature condition can directly lower the combustion efficiency of thrusters with obvious performance degradation, but there are no significant changes in the propellant mixing and liquid film cooling. It is concluded that the bipropellant thruster can reliably work at low temperatures around −40 °C for deep space probe operation.

Water provisioning increases caged worker bee lifespan and caged worker bees are living half as long as observed 50 years ago

The high loss rates of honey bee colonies drive research for solutions aimed to mitigate these losses. While honey bee colonies are superorganisms, experiments that measure the response to stressors often use caged individuals to allow for inference in a controlled setting. In an initial experiment, we showed that caged honey bees provisioned with various types of water (deionized, 1%NaCl in deionized, or tap) have greater median lifespans than those that did not. While researching the history of water provisioning in cage studies, we observed that the median lifespan of caged honey bees has been declining in the US since the 1970’s, from an average of 34.3 days to 17.7 days. In response to this, we again turned to historical record and found a relationship between this trend and a decline in the average amount of honey produced per colony per year in the US over the last 5 decades. To understand the relationship between individual bee lifespan and colony success we used an established honey bee population model (BEEHAVE) to simulate the predicted effects of decreased worker lifespans. Declines in downstream measures of colony population, overall honey production, and colony lifespan resulted from reduced worker bee lifespans. Modeled colony lifespans allowed us to estimate colony loss rates in a beekeeping operation where lost colonies are replaced annually. Resulting loss rates were reflective of what beekeepers’ experience today, which suggests the average lifespan of individual bees plays an important role in colony success.

Those who need it the most get it the least: Age specific reciprocal effects between social support and mental strain

Socioemotional selectivity theory and models of lifespan development of resources suggest that older workers may particularly benefit from social resources so as to maintain their well-being throughout their work-life span. However, the age-differential effects of social support at work have been rarely investigated. We hypothesised that age moderates the effects of colleagues' and supervisors' social support on mental strain, with strongest effects for older workers. A two-wave complete panel design (six months' time lag) was used. Self-reports from N = 334 nurses (age: 21–63 years) were gathered with established questionnaires: strain was measured by means of the irritation scale; social support from colleagues and supervisors by using a German adaptation of the social support scales. We proved factorial validity and measurement invariance across time points (CFA) and computed path models (SEM). As expected, age moderated the negative longitudinal effects of colleagues' social support on mental strain. Older nurses (≥45 years) benefited the most from colleagues' social support. However, mental strain in older nurses was associated with reduced social support from colleagues. Surprisingly with middle-aged nurses (35–44 years) an increase in colleagues' social support resulted in higher mental strain. No effects for supervisor support were observed. Results indicate that social support by colleagues is an important resource for older workers, but older workers are less likely to receive social support when mental strain is present. Moreover, the timing of social support across the work lifespan seems to be critical, as it might have detrimental effects in middle-aged workers.

An Innovative and Comprehensive Approach to Nursing Workforce Sustainability in Nova Scotia.

The COVID-19 pandemic has revealed long-standing deficiencies with existing nurse recruitment and retention approaches, resulting in critical shortages of nursing capacity that are set to worsen without appropriate action. Decades of evidence and experience suggest that a multi-pronged approach that fosters an enabling and supportive work environment for nurses across all stages of their working lifespan will be required to build a more sustainable nursing workforce. This paper demonstrates Nova Scotia's innovation in creating a comprehensive, evidence-informed approach to nursing workforce planning and management, including key strategic areas of action related to (1) facilitating entry into the workforce, (2) investing in the active workforce and (3) enhancing support for and managing attrition of the workforce. This paper also offers nursing leaders a series of reflections on current learnings in the implementation of this innovative and person-centred approach to nursing workforce sustainability. Recognizing the pressing need for action, Nova Scotia Health and provincial leaders have and are implementing strategic innovations to enhance the nursing workforce. These include: (1) investment in organizational capacity for evidence-based innovation, (2) development of collaborative relationships between both internal stakeholders and community partners and (3) creation of mechanisms for meaningful engagement and co-design of locally relevant innovative solutions.

Complicated microstructure transformation mechanism of the greenly grinding coating layer

The grinding surface mechanical property is important for its working life span, which is determined by the microstructure distribution. To improve the machining mechanical performance, the greenly grinding generated heat is utilized to generate the coating layer without extra liquid. However, the coating layer microstructure composite is difficult to predict due to the non-steady grinding temperature. A digital complicated microstructure transformation (DCM) model is established and coupled with the transient grinding heat based on the validated improved finite difference method. The austenization, the ferrite reverted transformation, the cementite precipitation, the bainite transformation and the martensite transformation are all considered and automatically distinguished according to the grinding coating CCT. The analytic results indicate that the larger grinding depth mainly increases the bainite content, which can be restricted by improving the feeding rate, and the quicker feeding rate can increase the martensite content by three times. Combined with the measurement of corresponding representative mechanical performances (hardness and the residual stress), the achieved model is verified as an effective tool to realize the microstructure prediction. The research brings about a novelty macro mechanical property control of the grinding coating layer and is significant for achieving higher mechanical performance in surface strengthening manufacturing components.

Eusociality and the Evolution of Aging in Superorganisms.

AbstractEusocial insects-ants, bees, wasps, and termites-are being recognized as model organisms to unravel the evolutionary paradox of aging for two reasons: (1) queens (and kings, in termites) of social insects outlive similarly sized solitary insects by up to several orders of magnitude and (2) all eusocial taxa show a divergence of long queen and shorter worker life spans, despite their shared genomes and even under risk-free laboratory environments. Traditionally, these observations have been explained by invoking the classical evolutionary aging theory: well-protected inside their nests, queens are much less exposed to external hazards than foraging workers, and this provides natural selection the opportunity to favor queens that perform well at advanced ages. Although quite plausible, these verbal arguments have not been backed up by mathematical analysis. Here, for the first time, we provide quantitative models for the evolution of caste-specific aging patterns. We show that caste-specific mortality risks are in general neither sufficient nor necessary to explain the evolutionary divergence in life span between queens and workers and the extraordinary queen life spans. Reproductive monopolization and the delayed production of sexual offspring in highly social colonies lead natural selection to inherently favor queens that live much longer than workers, even when exposed to the same external hazards. Factors that reduce a colony's reproductive skew, such as polygyny and worker reproduction, tend to reduce the evolutionary divergence in life span between queens and workers. Caste-specific extrinsic hazards also affect life span divergence, but to a much smaller extent than reproductive monopolization.

The response of dual-species bacterial biofilm to 2% and 5% NaOCl mixed with etidronic acid: A laboratory real-time evaluation using optical coherence tomography.

AimThe addition of etidronic acid (HEDP) to sodium hypochlorite (NaOCl) could increase the antibiofilm potency of the irrigant, whilst maintaining the benefits of continuous chelation. Studies conducted so far have shown that mixing HEDP with NaOCl solutions of relatively low concentration does not compromise the antibiofilm efficacy of the irrigant. However, the working lifespan of NaOCl may decrease resulting in a reduction of its antibiofilm efficacy over time (efficiency). In this regard, continuous irrigant replenishment needs to be examined. This study investigated the response of a dual‐species biofilm when challenged with 2% and 5% NaOCl mixed with HEDP for a prolonged timespan and under steady laminar flow.MethodologyDual‐species biofilms comprised of Streptococcus oralis J22 and Actinomyces naeslundii T14V‐J1 were grown on human dentine discs in a constant depth film fermenter (CDFF) for 96 h. Biofilms were treated with 2% and 5% NaOCl, alone or mixed with HEDP. Irrigants were applied under steady laminar flow for 8 min. Biofilm response was evaluated by means of optical coherence tomography (OCT). Biofilm removal, biofilm disruption, rate of biofilm loss and disruption as well as bubble formation were assessed. One‐way anova, Wilcoxon's signed‐rank test and Kruskal–Wallis H test were performed for statistical analysis of the data. The level of significance was set at a ≤.05.ResultsIncreasing NaOCl concentration resulted in increased biofilm removal and disruption, higher rate of biofilm loss and disruption and increased bubble formation. Mixing HEDP with NaOCl caused a delay in the antibiofilm action of the latter, without compromising its antibiofilm efficacy.ConclusionsNaOCl concentration dictates the biofilm response irrespective of the presence of HEDP. The addition of HEDP resulted in a delay in the antibiofilm action of NaOCl. This delay affects the efficiency, but not the efficacy of the irrigant over time.

Experience, vulnerability, or overload? Emotional job demands as moderator in trajectories of emotional well-being and job satisfaction across the working lifespan.

Employees exert emotional effort in order to perform their work effectively, albeit to varying degrees based on their occupation. These emotional job demands (EJDs) affect employees' well-being, yet evidence is mixed as to whether these effects are positive or negative. One limiting factor in extant studies is that they investigated short-term effects or cross-sectional relationships between EJDs (usually assessed at the employee level) and work outcomes. The present study used an accelerated longitudinal design with a 10-year timespan of data (effectively covering the whole working lifespan) to test the effects of EJDs at the occupational level on long-term trajectories of well-being. Drawing on the model of strengths and vulnerabilities integration (SAVI) from the lifespan psychology literature, we tested three competing effects: an experience effect (EJDs predict increased well-being), a vulnerability effect (EJDs predict diminished well-being), and an overload effect (a non-linear relationship in which very high levels lead to more unfavorable trajectories). Using data of N = 2,478 working adults in Germany drawn from the Socioeconomic Panel Study (SOEP), in tandem with data on EJDs from the Occupational Information Network (O*NET), we found an overload effect of EJDs on trajectories of positive affect and job satisfaction. However, EJDs did not influence trajectories of negative affect. We discuss the implications of our findings for theory and practice. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

The adult lifespan of the female honey bee (Apis mellifera): Metabolic rate, AGE pigment and the effect of dietary fatty acids

Female honey bees can be queens or workers and although genetically identical, workers have an adult lifespan of weeks while queens can live for years. The mechanisms underlying this extraordinary difference remain unknown. This study examines three potential explanations of the queen-worker lifespan difference. Metabolic rates were similar in age-matched queens and workers and thus are not an explanation. The accumulation of fluorescent AGE pigment has been successfully used as a good measure of cellular senescence in many species. Unlike other animals, AGE pigment level reduced during adult life of queens and workers. This unusual finding suggests female honey bees can either modify, or remove from their body, AGE pigment. Another queen-worker difference is that, as adults, workers eat pollen but queens do not. Pollen is a source of polyunsaturated fatty acids. Its consumption explains the queen-worker difference in membrane fat composition of female adult honey bees which has previously been suggested as a cause of the lifespan difference. We were able to produce “queen-worker” membrane differences in workers by manipulation of diet that did not change worker lifespan and we can, thus, also rule out pollen consumption by workers as an explanation of the dramatic queen-worker lifespan difference.

Antagonistic pleiotropy and the evolution of extraordinary lifespans in eusocial organisms.

Queens of eusocial species live extraordinarily long compared to their workers. So far, it has been argued that these lifespan divergences are readily explained by the classical evolutionary theory of ageing. As workers predominantly perform risky tasks, such as foraging and nest defense, and queens stay in the well‐protected nests, selection against harmful genetic mutations expressed in old age should be weaker in workers than in queens due to caste differences in extrinsic mortality risk, and thus, lead to the evolution of longer queen and shorter worker lifespans. However, these arguments have not been supported by formal models. Here, we present a model for the evolution of caste‐specific ageing in social insects, based on Williams’ antagonistic pleiotropy theory of ageing. In individual‐based simulations, we assume that mutations with antagonistic fitness effects can act within castes, that is, mutations in early life are accompanied by an antagonistic effect acting in later life, or between castes, where antagonistic effects emerge due to caste antagonism or indirect genetic effects between castes. In monogynous social insect species with sterile workers, large lifespan divergences between castes evolved under all different scenarios of antagonistic effects, but regardless of the degree of caste‐specific extrinsic mortality. Mutations with antagonistic fitness effects within castes reduced lifespans of both castes, while mutations with between‐caste antagonistic effects decreased worker lifespans more than queen lifespans, and consequently increased lifespan divergences. Our results challenge the central explanatory role of extrinsic mortality for caste‐specific ageing in eusocial organisms and suggest that antagonistic pleiotropy affects castes differently due to reproductive monopolization by queens, hence, reproductive division of labor. Finally, these findings provide new insights into the evolution of tissue‐specific ageing in multicellular organisms in general.

Application of heterostructured CdS/ZnS quantum dots as luminescence down-shifting layer in P3HT:PCBM solar cells

Organic photovoltaic devices (OPVs) have a shorter working lifespan and lower power conversion efficiency if compared to traditional silicon-based solar cells. Intending to increase the lifespan and improve the performance of OPVs, in this work we have applied a layer of Cadmium Sulfide (CdS) Quantum Dots (QDs) encapsulated in Zinc Sulfide (CdS/ZnS) to act as a luminescence down-shifting (LDS) layer in poly(3-hexylthiophene-2,5-diyl) (P3HT):phenyl-C61-butyric-acid-methyl ester (PCBM) organic solar cell. The QDs were synthesized by the hot injection route and deposited by casting on a device with ITO/PEDOT:PSS/P3HT:PCBM/Al structure. OPVs with and without the LDS layer of QDs were tested over time of exposure to the illumination of an AM1.5 solar simulator. The results showed that in the cells with the QDs layer, there was an increase in Open Circuit Voltage (Voc), Short Circuit Current Density (Jsc), Fill Factor (FF), and Power Conversion Efficiency (η), after 70 min of exposure, reaching a peak of these parameter values around 120 min of light exposure, while in the cells without the LDS layer, these parameters have decreased over the entire exposure time. This behavior was explained taking into account the improvement of the photoluminescence (PL) yield by the QDs film and the illumination process.

Boosting the rate capability and working lifespan of K/Co co-doped Na3V2(PO4)3/C for sodium ion batteries

Na3V2(PO4)3 (NVP) has been deemed to be a prospective cathode for sodium ion batteries (SIBs) duo to its high structural stability and flat voltage platform. Herein, a series of K/Co co-doped NVP composites with optimized sodium storage property are produced via a feasible sol-gel method. Significantly, the introduced K+ has substituted of Na+ at Na1 site, strictly demonstrated by the Rietveld refinement results. Meanwhile, this substitution has hardly influence on the reversible de/insertion of Na+ situated at Na2 site. Moreover, the beneficial K+ with larger ionic radius can act as the pillar ion to improve the structural stability efficiently. Furthermore, the replacement of V3+ by Co2+ facilitates to enlarging the interplanar spacing in crystal structure, resulting in accelerating the Na+ migration effectively. Moreover, substitution with low valence element (Co2+vs. V3+) can generate the favorable holes to increase the intrinsic electronic conductivity. Notably, doping with appropriate content of K/Co elements favors to reduce the particle size and shorten the pathway for Na+ transformation, distinctly boosting the apparent ionic diffusivity. Specifically, K/Co co-doping induces to forming the unique mesoporous morphology, immensely enlarging the specific surface area of active grains and therefore facilitating the infiltration between the particles and electrolyte. Comprehensively, the optimized K0.1Co0.05-NVP/C exhibits an outstanding electrochemical performance. It shows a high initial capacity of 122.7 mA h g−1 at 0.1 C, which is higher than the theoretical value of NVP (117.6 mA h g−1). It can release an initial capacity of 100.9 mA h g−1 at 1 C and maintain 71.0 mA h g−1 after 500 cycles. Moreover, the reversible capacity can be achieved as 98.8 mA h g−1 at a high rate of 10 C and a favorable retention of 75.9% can be obtained after 400 cycles. Besides, the kinetic characteristics for the modified K0.1Co0.05-NVP/C cathode are superior than those of pristine NVP/C. Specifically, it reveals a relatively high diffusion coefficient of Na+ (0.53 × 10−10 cm2 s−1). Thus, the modified K/Co co-doped NVP/C sample can be a promising cathode material for SIBs.