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A significant obstacle in the development of phosphor-converted white-laser diodes (pc-wLDs) is associated with the laser-induced luminescence saturation of phosphors. YAG:Ce is a canonical yellow-emitting phosphor. However, there has been few systematic research of measurement and understanding of the luminescence saturation in YAG:Ce yet. Here, we analyze the luminescence saturation of a single-crystal YAG:Ce with a unique phosphor geometry. A novel characterization method, which enables the optical signals to be fully collected and analyzed, is introduced. The effects of both laser power and laser power density on the luminescence properties and colorimetric properties of the YAG:Ce are studied systematically. The results show that a single-crystal YAG:Ce has a high saturation threshold (over 360 W/mm2) so that only a very slight saturation behavior can be observed at a high power density. Furthermore, a pc-wLDs light source based on the combination of a single laser diode and a YAG:Ce phosphor exhibits remarkable efficiency and stability. Under the excitation of a 3.38 W blue laser (∼100 W/mm2), the white light emission with the luminous flux of 465 lm, the luminous efficacy (LE) of 145 lm/W, and the correlated color temperature (CCT) of 4980 K can be achieved. Image 1 [ABSTRACT FROM AUTHOR]

Abstract Correlated Colour Temperature (CCT) of lighting may affect not only occupant visual perception, but also other indoor environment perceptions, such as perceptions of the thermal environment or the air quality. This study aimed at quantifying the association between CCT of white LED lighting and subjective perceptions and performance at operative temperatures at the upper and lower borders and in the middle of the comfort range. Higher CCT was significantly associated with decreasing thermal sensation, but only at the thermally neutral condition. Female subjects responded stronger to changes in CCT than male subjects. Under all temperature conditions, CCT was clearly associated with the perceived brightness of the light, and at 22 °C also with the perceived air quality and with subjectively assessed alertness. CCT had no effect on the measured performance of a d2 task. At 22 °C, the observed decrease in thermal sensation when CCT went from 2700 K to 6200 K was equivalent to a difference in operative temperature of 1.7 °C. With an assumed neutral CCT of 4500 K (middle of range), a decreased heating set point in an office building, corresponding to an equivalent shift in CCT from 4500 K to 2700 K, resulted in a reduction of around 8% of the building's total annual energy use. However, this assumes ideal conditions without influence from daylight, light from PC monitors, or coloured surfaces and other potentially disturbing factors. Highlights • Increased correlated colour temperature significantly decreased thermal sensation at a neutral operative temperature. • Increased correlated colour temperature increased the perceived brightness of the light. • The observed shift in thermal sensation corresponded to a reduction of around 8% of a building's total annual energy use. [ABSTRACT FROM AUTHOR]

Background: Hygiene promotion interventions are likely to be more effective if they target the determinants of handwashing behaviour. Synthesis of the evidence on the determinants of handwashing behaviour is needed to enable practitioners to use evidence in hygiene promotion programming.Purpose: To identify, define and categorise the determinants of handwashing behaviour in domestic settings and to appraise the quality of this evidence.Methods: We conducted an integrative review, searching three databases for terms related to handwashing and behaviour change determinants. Studies were summarised and their quality assessed against a pre-defined set of criteria for qualitative, quantitative and mixed-method studies. Data on determinants were extracted and classified according to a predefined theoretical taxonomy. The effect of each association between a determinant and handwashing behaviour was summarised and weighted based on the quality of evidence provided. Determinants that were reported more than three times were combined into a meta-association and included in the main analysis. Sub-analyses were done for studies conducted during outbreaks or humanitarian crises.Results: Seventy-eight studies met the criteria. Of these, 18% were graded as 'good quality' and 497 associations between determinants and handwashing behaviour were extracted. We found that 21% of these associations did not clearly define the determinant and 70% did not use a valid or reliable method for assessing determinants and/or behaviour. Fifty meta-associations were included in the main analysis. The determinants of handwashing that were most commonly reported were knowledge, risk, psychological trade-offs or discounts, characteristic traits (like gender, wealth and education), and infrastructure. There was insufficient data to draw conclusions about the determinants of behaviour in outbreaks or crises.Conclusions: This review demonstrates that our understanding of behavioural determinants remains sub-optimal. We found that there are limitations in the way behavioural determinants are conceptualised and measured and that research is biased towards exploring a narrow range of behavioural determinants. Hygiene promotion programmes are likely to be most successful if they use multi-modal approaches, combining infrastructural improvement with 'soft' hygiene promotion which addresses a range of determinants rather than just education about disease transmission. [ABSTRACT FROM AUTHOR]

• The extent to which bifacial spectral effects are dependent on the albedo, sky conditions, and mounting structure are quantified. • Backside spectral mismatch can be reasonably approximated using spectral albedo measurements with just 5–8 narrow band channels. • The normalized difference vegetation index is a good predictor of the backside spectral effects present in bifacial systems. • An open access spectral dataset consisting of spectral albedo, spectral global horizontal irradiance, and spectral beam measurements is made freely available. This paper analyzes 15-months of spectral albedo measurements collected at the Technical University of Denmark (55.6°N, 12.1°E). High-resolution spectroradiometers are used to monitor four albedo scenarios, which include green vegetation, dry vegetation, gravel, and snow. Spectral mismatch and spectral impact are calculated for the front and backside of three different bifacial cell concepts mounted on horizontal single axis trackers and fixed-tilt substructures. The spectral nature of albedo is shown to have significant influence on bifacial photovoltaic performance wherein backside spectral impact as high as 1.20 is observed for fixed-tilt systems above green vegetation and as low as 0.98 for systems above snow. The results reveal that spectral impact is always lower on tracked than fixed-tilt systems because a greater fraction of sky diffuse light reaches the backside of tracked systems. Given the variety of albedos tested here, we find that the normalized difference vegetation index is a good predictor of backside spectral effects. When the high-resolution measurements are truncated to 4 to 8 carefully selected wavelengths, we find that this limited measurement resolution sufficiently captures the seasonal spectral albedo fluctuations that influence bifacial photovoltaic energy production. Finally, to alleviate the dearth of spectral datasets presently available to the PV community, the spectral irradiance and albedo measurements are made freely available in open access format (https://doi.org/10.11583/DTU.14695437.v1). [ABSTRACT FROM AUTHOR]

The majority of undiscovered hydrothermal vent fields are thought to be located on slow and ultraslow spreading ridges. Locating new vent sites on these ridges is important due to their tendency to host large seafloor massive sulfide deposits. It is also important as it can increase our understanding of the tectonics at ultraslow spreading ridges as well as giving us an understanding of how hydrothermal venting in these regions affect and interact with the surrounding water column. To assess the hydrothermal productivity of the slow to ultraslow spreading Mohns and Knipovich ridge segments of the Arctic Mid-Ocean Ridge we used the primordial isotope 3He. Due to the conservative nature of 3He, this isotope can function as a tracer both for hydrothermal activity and on the ocean current pathways. In addition to assessing the hydrothermal productivity of the ridges we also studied the impact the ridges have on ocean circulation. Between 2006 and 2016, 400 water samples were collected along the Mohns Ridge and the Knipovich Ridge and 117 samples were collected in two transects crossing each ridge. The results show that the surface mixed layer (500–0 m depth) directly above each ridge has higher than equilibrium values of δ3He, which we interpret as an effect of the bottom topography on the vertical mixing. We also observe direct indications of at least two undiscovered vent sites along the Mohns Ridge, making the total count of 7 vent fields along this 550 km ridge segment, which gives a vent field frequency (F s) of 1.27 sites/100 km. This number is comparable to the vent field frequency on other ultraslow ridges. By comparing the current speed to non-buoyant plume measurements obtained at the previously discovered Loki's Castle and the Jan Mayen vent fields (JMVF) we made an estimate of the 3He flux at these vent fields. This estimate gave a flux of 0.22 mmol/km/mm/yr from Loki's Castle, which is well below the world's average of 0.33 mmol/km/mm/yr. However, the flux rate estimated here is comparable to estimates previously calculated from the ultraslow Gakkel ridge. The northeastern termination of the Mohns Ridge, where Loki's Castle is located, is also the thinnest part of the ridge segment indicating a low magmatic influence. The flux rate of the JMVF was 0.40 mmol/km/mm/yr and thus higher than the global average. This could indicate an influence from the Jan Mayen hot spot as similar flux rates has been found at other hot spot influenced vent sites. This study not only illuminates the hydrothermal productivity of ultraslow spreading ridges, but also adds a considerable dataset of helium isotopes in Nordic Seas. [ABSTRACT FROM AUTHOR]

Diffuse low-temperature hydrothermal vents on the seafloor host neutrophilic microaerophilic Fe-oxidizing bacteria that utilize the Fe(II) supplied by hydrothermal fluids and produce intricate twisted and branching extracellular stalks. The growth behavior of Fe-oxidizing bacteria in strongly opposing gradients of Fe(II) and O 2 have been thoroughly investigated in laboratory settings to assess whether extracellular stalks and aligned biomineralized fabrics may serve as biosignatures of Fe-oxidizing bacteria and indications of palaeo-redox conditions in the rock record. However, the processes controlling the growth of biogenic Fe-oxyhydroxide deposits in natural, modern hydrothermal systems are still not well constrained. In this study, we aimed to establish how variations in the texture of stratified hydrothermal Fe-oxyhydroxide deposits are linked to the physicochemical conditions of the hydrothermal environment. We conducted 16S rRNA gene analyses, microscopy and geochemical analyses of laminated siliceous Fe-mounds from the Jan Mayen Vent Fields at the Arctic Mid-Ocean Ridge. Chemical analyses of low- and high-temperature hydrothermal fluids were performed to characterize the hydrothermal system in which the Fe-deposits form. Our results reveal synchronous inter-laminar variations in texture and major and trace element geochemistry. The Fe-deposits are composed of alternating porous laminae of mineralized twisted stalks and branching tubes, Mn-rich horizons with abundant detrital sediment, domal internal cavities and thin P- and REE-enriched lamina characterized by networks of ≪1 μm wide fibers. Zetaproteobacteria constitute one third of the microbial community in the surface layer of actively forming mounds, indicating that microbial Fe-oxidation is contributing to mound accretion. We suggest that Mn-oxide precipitation and detrital sediment accumulation take place during periodically low hydrothermal fluid discharge conditions. The elevated concentrations of P and REE in distinct laminae suggest Fe-cycling and accumulation of diagenetic species at depth in the deposits during hydrothermal quiescence and co-precipitation of these species with Fe-oxyhydroxides at the mound surface with reinitiated hydrothermal discharge. The origin of the low-temperature hydrothermal source fluid and the Fe-deposits are evident by low LREE/HREE ratios and negative Eu-anomalies, which clearly differ from the LREE and Eu enrichment of nearby high-temperature white smoker venting fluids. Our study demonstrates that hydrothermal fluctuations exert the primary control on the formation of laminae and the activity of Fe-oxidizing bacteria in marine hydrothermal Fe-deposits and indicates that REE-patterns may be used to distinguish high-temperature plume fallout and biomineralized low-temperature Fe-deposits in the rock record. [ABSTRACT FROM AUTHOR]

Abstract: Formation pathways of ancient siliceous iron formations and related Fe isotopic fractionation are still not completely understood. Investigating these processes, however, is difficult as good modern analogues to ancient iron formations are scarce. Modern siliceous Fe oxyhydroxide deposits are found at marine hydrothermal vent sites, where they precipitate from diffuse, low temperature fluids along faults and fissures on the seafloor. These deposits exhibit textural and chemical features that are similar to some Phanerozoic iron formations, raising the question as to whether the latter could have precipitated from diffuse hydrothermal fluids rather than from hydrothermal plumes. In this study, we present the first data on modern Fe oxyhydroxide deposits from the Jan Mayen hydrothermal vent fields, Norwegian-Greenland Sea. The samples we investigated exhibited very low δ56Fe values between −2.09‰ and −0.66‰. Due to various degrees of partial oxidation, the Fe oxyhydroxides are with one exception either indistinguishable from low-temperature hydrothermal fluids from which they precipitated (−1.84‰ and −1.53‰ in δ56Fe) or are enriched in the heavy Fe isotopes. In addition, we investigated Fe isotope variations in Ordovician jasper beds from the Løkken ophiolite complex, Norway, which have been interpreted to represent diagenetic products of siliceous ferrihydrite precursors that precipitated in a hydrothermal plume, in order to compare different formation pathways of Fe oxyhydroxide deposits. Iron isotopes in the jasper samples have higher δ56Fe values (−0.38‰ to +0.89‰) relative to modern, high-temperature hydrothermal vent fluids (ca. −0.40‰ on average), supporting the fallout model. However, formation of the Ordovician jaspers by diffuse venting cannot be excluded, due to lithological differences of the subsurface of the two investigated vent systems. Our study shows that reliable interpretation of Fe isotope variations in modern and ancient marine Fe oxyhydroxide deposits depends on comprehensive knowledge of the geological context. Furthermore, we demonstrate that very negative δ56Fe values in such samples might not be the result of microbial dissimilatory iron reduction, but could be caused instead by inorganic reactions. [Copyright &y& Elsevier]