To investigate the association between smartphone use and refractive error in teenagers using the Myopia app.
Cross-sectional population-based study.
A total of 525 teenagers 12 to 16 years of age ...from 6 secondary schools and from the birth cohort study Generation R participated.
A smartphone application (Myopia app; Innovattic) was designed to measure smartphone use and face-to-screen distance objectively and to pose questions about outdoor exposure. Participants underwent cycloplegic refractive error and ocular biometry measurements. Mean daily smartphone use was calculated in hours per day and continuous use as the number of episodes of 20 minutes on screen without breaks. Linear mixed models were conducted with smartphone use, continuous use, and face-to-screen distance as determinants and spherical equivalent of refraction (SER) and axial length-to-corneal radius (AL:CR) ratio as outcome measures stratified by median outdoor exposure.
Spherical equivalent of refraction in diopters and AL:CR ratio.
The teenagers on average were 13.7 ± 0.85 years of age, and myopia prevalence was 18.9%. During school days, total smartphone use on average was 3.71 ± 1.70 hours/day and was associated only borderline significantly with AL:CR ratio (β = 0.008; 95% confidence interval CI, –0.001 to 0.017) and not with SER. Continuous use on average was 6.42 ± 4.36 episodes of 20-minute use without breaks per day and was associated significantly with SER and AL:CR ratio (β = –0.07 95% CI, –0.13 to –0.01 and β = 0.004 95% CI, 0.001–0.008, respectively). When stratifying for outdoor exposure, continuous use remained significant only for teenagers with low exposure (β = –0.10 95% CI, –0.20 to –0.01 and β = 0.007 95% CI, 0.001–0.013 for SER and AL:CR ratio, respectively). Smartphone use during weekends was not associated significantly with SER and AL:CR ratio, nor was face-to-screen distance.
Dutch teenagers spent almost 4 hours per day on their smartphones. Episodes of 20 minutes of continuous use were associated with more myopic refractive errors, particularly in those with low outdoor exposure. This study suggested that frequent breaks should become a recommendation for smartphone use in teenagers. Future large longitudinal studies will allow more detailed information on safe screen use in youth.
Recently, the electronic personal mobility has been focused for sustainable development goals. The synthetic leather is used as rider suit of personal mobility for comfort. But, the damage of rider ...suit using synthetic leather will be occurred under outdoor exposure environment. So, this study was examined the effect of outdoor exposure environment on tensile property of synthetic leather (front: polyurethane, back: polyester) for durability of raider suit of personal mobility. The maximum test time of outdoor exposure test was one month (start time: July 2022, test place: Japan (Hino, Tokyo)). The outdoor exposure test was conducted based on Japanese Industrial Standard (JIS) Z 2381. The test surface was front side. Before and after outdoor exposure tests, static tensile tests of synthetic leathers were conducted based on JIS K 6552. Test temperature and humidity were room temperature and 65%RH, respectively. As a result, tensile property of synthetic leather decreased after outdoor exposure test. Generally, the tensile property of polyurethane decrease with an increase of test time. The constituent material on surface of synthetic leather was probably degraded by ultraviolet irradiation. Therefore, tensile property of synthetic leather for personal mobility was mainly affected by ultraviolet irradiation under outdoor exposure environment.
•Different curing types give similar a carbonation behavior in real structures.•The ratio of unsheltered to sheltered carbonation depth is strength dependent.•New equation is proposed to account for ...effect of shelter on natural carbonation.•New equation is proposed to account for effect of CO2 level on carbonation.•The proposed equations could be used in future carbonation prediction models.
In the literature, the effects of curing, sheltering and CO2 concentration under natural carbonation are not fully understood. There is either controversy or limited research available regarding these factors, while most investigations are based on accelerated carbonation. The currently available research on natural carbonation is particularly constrained and limited. From a practical viewpoint, natural carbonation is more important as it represents the behavior of real structures.
This paper reviews the influences of different curing methods and their durations; sheltered and unsheltered exposure conditions, and different atmospheric CO2 concentration levels, on carbonation of concrete under the natural outdoor exposure environment. The various curing methods examined are moist-curing, steam-, air- and oven-curing. It is found that curing effects are coupled with the type of cement. For cements containing no more than 30% fly ash or 50% slag, three-day curing is sufficient to stabilize long-term strength and carbonation behavior of concrete under site conditions. Different types of normal curing do not significantly alter natural carbonation behavior. An equation is suggested which accounts for the effect of unsheltered outdoor exposure on carbonation. Also, correction factors are proposed to account for different atmospheric CO2 levels under natural carbonation.
In this work, a dual-action self-healing coating with excellent photothermal response to both near-infrared (NIR) laser and sunlight irradiation was prepared. The coating was composed of a shape ...memory epoxy matrix embedded with poly (ε-caprolactone) (PCL) microspheres, the surface of which was covered by titanium nitride nanoparticles (TiN NPs) to achieve the superior photothermal conversion ability. Upon light irradiation, the PCL@TiN composite microspheres could efficiently absorb light energy and generate sufficient heat to induce the shape memory recovery of coating defect as well as the melting of PCL to seal the scratch. Morphology observation and electrochemical measurements proved that the coating incorporated with 10 wt% of PCL@TiN microspheres presented an excellent self-healing performance under 30 s of NIR illumination to recover the barrier property. In addition, the photothermal conversion of PCL@TiN microspheres could accelerate the evaporation of water around the coating scratch, hence restraining the corrosion activity in the damaged region. The outdoor exposure test on the atmospheric corrosion monitor (ACM) covered by the coating confirmed that sunlight also benefited to achieve the prominent self-healing performance and shorten the water evaporation time, leading to much reduced corrosion current outputs hence improved corrosion protection property.
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•PCL@TiN microspheres with photothermal conversion property are developed.•Photothermal response triggers the “scratch closure and microsphere sealing” dual-action self-healing mechanism.•Efficient photothermal conversion makes the self-healing to be realized within 30s NIR laser irradiation.•Photothermal effect accelerates the evaporation of water around the coating scratch.•Outdoor exposure test demonstrates that sunlight irradiation also benefits to induce the self-healing effect of coating.
Understanding the impact of climate stressors on photovoltaic (PV) backsheet degradation in real-use conditions is critical to improve the accelerated testing exposures, extend the backsheet ...lifetime, and increase the confidence in PV reliability. Here, in this work, a total of 33 PV module backsheets were retrieved from six climatic zones worldwide with 2 - 28 years of exposure. These modules included five types of backsheet air-side materials (or outer layer): poly(vinylidene fluoride) (PVDF), poly(tetrafluoroethylene-co-hexafluoropropylene-co-vinylidene fluoride) (THV), poly(vinyl fluoride) (PVF), poly(ethylene terephthalate) (PET), and polyamide (PA). Attenuated total reflection Fourier-transform infrared spectroscopy (ATR-FTIR) was used to identify air-side materials. The degradation induced color change, gloss loss, and chemical material changes analyzed using optical microscopy, differential scanning calorimetry (DSC), scanning electron microscopy (SEM), colorimetry (yellowness index (YI)), and gloss measurements. PVDF, THV, and PVF air-side layer backsheets, in particular PVF, had minimal degradation in the air-side layer appearance and chemical structures after exposure in different climatic zones. The PET air-side backsheets exhibited obvious color increase (22.55 YI units after about 9 years exposure) and the PA/PA/PA backsheets showed large gloss loss (up to 76.4 %) relative to the unexposed backsheets. Severe cracks between cells that penetrated through the entire thickness of backsheets are observed on PA/PA/PA backsheets after 4-6 years of exposure in 6 climatic zones. The current indoor exposure standards were not sufficient to identify this degradation type. However, fluoropolymer based PV backsheets showed lower levels of degradation predictors and increased climatic resistance. Specific samples (PVF) showed little change from baseline after 28 years of outdoor exposure.
Understanding the impact of climate stressors on photovoltaic (PV) backsheet degradation in real-use conditions is critical to improve the accelerated testing exposures, extend the backsheet ...lifetime, and increase the confidence in PV reliability. In this work, a total of 33 PV module backsheets were retrieved from six climatic zones worldwide with 2 - 28 years of exposure. These modules included five types of backsheet air-side materials (or outer layer): poly(vinylidene fluoride) (PVDF), poly(tetrafluoroethylene-co-hexafluoropropylene-co-vinylidene fluoride) (THV), poly(vinyl fluoride) (PVF), poly(ethylene terephthalate) (PET), and polyamide (PA). Attenuated total reflection Fourier-transform infrared spectroscopy (ATR-FTIR) was used to identify air-side materials. The degradation induced color change, gloss loss, and chemical material changes analyzed using optical microscopy, differential scanning calorimetry (DSC), scanning electron microscopy (SEM), colorimetry (yellowness index (YI)), and gloss measurements. PVDF, THV, and PVF air-side layer backsheets, in particular PVF, had minimal degradation in the air-side layer appearance and chemical structures after exposure in different climatic zones. The PET air-side backsheets exhibited obvious color increase (22.55 YI units after about 9 years exposure) and the PA/PA/PA backsheets showed large gloss loss (up to 76.4 %) relative to the unexposed backsheets. Severe cracks between cells that penetrated through the entire thickness of backsheets are observed on PA/PA/PA backsheets after 4-6 years of exposure in 6 climatic zones. The current indoor exposure standards were not sufficient to identify this degradation type. However, fluoropolymer based PV backsheets showed lower levels of degradation predictors and increased climatic resistance. Specific samples (PVF) showed little change from baseline after 28 years of outdoor exposure.
•Retrieved module backsheet characterization.•Diverse climatic exposure.•Inhomogeneous backsheet degradation.
Durability studies of solar reflectors: A review García-Segura, A.; Fernández-García, A.; Ariza, M.J. ...
Renewable & sustainable energy reviews,
September 2016, 2016-09-00, 20160901, Letnik:
62
Journal Article
Recenzirano
Reflectors are a vital part of a concentrating solar thermal power plant. One of their most important characteristics is their durability, which entails the maintenance of their optical properties ...throughout their service lifetime, aimed at 10–30 years or more. The assessment of their optical durability involves the design of two types of aging tests, outdoor exposure testing under real ambient conditions and accelerated exposure testing in weathering chambers under simulated conditions. After exposure to different stress factors for certain periods of time, the optical performance of reflectors is evaluated mainly in terms of reflectance, but also regarding qualitative parameters such as their visual appearance and degradation patterns. The ultimate goal of a durability study is to conceive meaningful accelerated testing procedures that simulate real outdoor degradation in a short time and provide service lifetime estimates for a certain type of reflector at a specific site. To achieve this, more research on service lifetime prediction should be conducted and the standardization of accelerated testing procedures and reflectance evaluation methods should become widespread, to obtain comparable representative results. In this article, the most significant durability studies performed on the three main types of solar reflectors (glass-based, aluminum and silvered-polymer) and prospective approaches for improving future endeavors are discussed.
The longevity of geopolymer-based radiative cooling coatings is questionable due to their hydrophilic nature. This study used four hydrophobic agents - sodium methyl silicate (SMS), ...polydimethylsiloxane (PDMS), polytetrafluoroethylene (PTFE), and triethoxyoctylsilane (TEOS) - to modify the surface hydrophobicity of geopolymer while maintaining its optical properties. The optimal agent contents were determined by optical performance and water contact angle: 5 % for SMS, 10 % for 50 cP viscosity PDMS, and a single-layer thickness for PTFE and TEOS (60 °C). The agents' working mechanisms were analyzed using FTIR and XRD characterization: SMS forms a hydrophobic alkylsilanol layer by reacting with the geopolymer's silanol group; PDMS lowers the geopolymer's surface energy with its hydrophobic methyl groups; PTFE's low electric polarizability is due to its fluorine content; and TEOS replaces the geopolymer surface's hydroxyl groups with hydrophobic octyl groups. The long-term durability of these modified coatings was evaluated through outdoor exposure tests, resulting in total solar reflectance losses of 0.74 %, 1.9 %, 3.9 %, and 0.05 % respectively. A slight reduction in the water contact angle confirmed their enduring hydrophobic characteristics. These modification methods open up possibilities for the practical use of hydrophobic geopolymer radiative cooling coatings.
•SMS, PDMS, PTFE and TEOS could tailor geopolymer’s hydrophobic properties.•If designed well, the effect of modifiers on the optical properties was ignorable.•SMS and TEOS reacted with geopolymer, but PDMS and PTFE did not.•Outdoor exposure revealed a limited reduction in optical and hydrophobic properties.•SMS, PTFE and TEOS were beneficial for the bond strength, but PDMS was not.
•Surface erosion bring to light underlying layer with different features respect than the old ones.•An ultrasonic quality index (vri) between good and very good was detected after ageing.•Secondary ...calcite patina could increase the hardness of the sample.•Surface roughness regulates the gas-driven permeability.
Building stone materials have to satisfy long-term durability requirements in different environments in terms of mechanical strength and resistance to aggressive conditions. Several studies and field observations show that weathering on geo-materials is related to average annual precipitation and temperature.
The decay also depends on salts air/soil concentrations and biological agents, but the more harmful impact is given by greenhouse gas (e.g. CO2, SOX, NOX, O3). These last induce the acidification of the rain and runoff waters. Nowadays, decay prediction is required in order to estimate the behaviour of stone materials over time. This research represents a second part of a previous work where the response to weathering of some construction materials used in ancient and contemporary architecture and cultural heritage has been evaluated by a laboratory simulation of hot-summer Csa Mediterranean climate. Simulation consists of accelerate ageing test on climate chamber by reproducing macro (e.g. daily and seasonal cycles of temperature, relative humidity, CO2 air concentration) and micro (e.g. rain, soil capillary rising) environments. Some non-destructive testing were executed to evaluate some physical–mechanical “decay markers” before and after the ageing. Test caused both decreasing and increasing of Leeb D hardness, decreases of permeability and a general decrease of ultrasonic speed, mainly due to the formations of patinas, crusts and efflorescences on the surfaces.
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