Low Radiation Intensity Research Articles

Investigation on Energetic Efficiency of Reactor Systems for Oxidation of Micro-Pollutants by Immobilized Active Titanium Dioxide Photocatalysis

In this work, the degradation performance for the photocatalytic oxidation of eight micro-pollutants (amisulpride, benzotriazole, candesartan, carbamazepine, diclofenac, gabapentin, methlybenzotriazole, and metoprolol) within real secondary effluent was investigated using three different reactor designs. For all reactor types, the influence of irradiation power on its reaction rate and energetic efficiency was investigated. Flat cell and batch reactor showed almost similar substance specific degradation behavior. Within the immersion rotary body reactor, benzotriazole and methyl-benzotriazole showed a significantly lower degradation affinity. The flat cell reactor achieved the highest mean degradation rate, with half time values ranging from 5 to 64 min with a mean of 18 min, due to its high catalysts surface to hydraulic volume ratio. The EE/O values were calculated for all micro-pollutants as well as the mean degradation rate constant of each experimental step. The lowest substance specific energy per order (EE/O) values of 5 kWh/m3 were measured for benzotriazole within the batch reactor. The batch reactor also reached the lowest mean values (11.8–15.9 kWh/m3) followed by the flat cell reactor (21.0–37.0 kWh/m3) and immersion rotary body reactor (23.9–41.0 kWh/m3). Catalyst arrangement and irradiation power were identified as major influences on the energetic performance of the reactors. Low radiation intensities as well as the use of submerged catalyst arrangement allowed a reduction in energy demand by a factor of 3–4. A treatment according to existing treatment goals of wastewater treatment plants (80% total degradation) was achieved using the batch reactor with a calculated energy demand of 7000 Wh/m3.

SrTiO3/CuNi‐Heterostructure‐Based Thermopile for Sensitive Human Radiation Detection and Noncontact Human–Machine Interaction

AbstractNoncontact interactive technology provides an intelligent solution to mitigate public health risks from cross‐infection in the era of COVID‐19. The utilization of human radiation as a stimulus source is conducive to the implementation of low‐power, robust noncontact human–machine interaction. However, the low radiation intensity emitted by humans puts forward a high demand for photodetection performance. Here, a SrTiO3−x/CuNi‐heterostructure‐based thermopile is constructed, which features the combination of high thermoelectric performance and near‐unity long‐wave infrared absorption, to realize the self‐powered detection of human radiation. The response level of this thermopile to human radiation is orders of magnitude higher than those of low‐dimensional‐materials‐based photothermoelectric detectors and even commercial thermopiles. Furthermore, a touchless input device based on the thermopile array is developed, which can recognize hand gestures, numbers, and letters in real‐time. This work offers a reliable strategy to integrate the spontaneous human radiation into noncontact human–machine interaction systems.

Experimental and numerical investigations of solar charging performances of 3D porous skeleton based latent heat storage devices

Volumetric-absorption-based solar charging via phase change processes is an emerging technology to harvest solar energy, however, how pore-scale radiation transport interacts with latent heat thermal energy storage processes is still vague. In this paper, volumetric-absorption-based solar charging processes at pore scale are investigated by experiments and numerical simulations based on Monte Carlo ray tracing coupled with the Finite Volume Method. The solar radiation transport, temperature distribution, liquid fraction, and solar thermal energy storage efficiency are systematically evaluated under different radiation intensities and skeleton thermal conductivities. Compared to the traditional surface-absorption-based mode, solar thermal energy storage efficiency of the volumetric-absorption mode is enhanced by 94% due to presence of multi-region heat sources. The solar thermal energy storage efficiency reaches a peak value of 54.09% at a radiation intensity of 10 kW·m−2. That is because low radiation intensities increase the melting time while too high intensities lead to large temperature nonuniformity, leading to high heat losses for both scenarios. Increasing the skeleton thermal conductivity can continuously improve the efficiency by reducing temperature nonuniformity, but further enhancement becomes marginal for thermal conductivity over 90 W·m−1·K−1. This work paves the way for the design and deployment of efficient integrated solar thermal conversion and latent heat storage systems.

Ventilating aged-care center based on solar chimney: Design and theoretical analysis

Natural ventilation is considered the first suggestion for COVID-19 prevention in buildings by the World Health Organization (WHO). Solar chimney’s viability in aged care centers or similar facilities was analyzed numerically and theoretically. A new solar chimney design was proposed to reduce the cross-infection risk of COVID-19 based on an airflow path through window, ceiling vent, attic, and then chimney cavity. Solar chimney performance, quantified by the natural ventilation rate, presented power function with window area, ceiling vent area, cavity height, and solar radiation. The ceiling vent is suggested to be closer to the corridor to enhance the performance and ventilation coverage of the room. A cavity gap of 1.0 m is recommended to balance the ventilation performance and construction cost. A theoretical model was also developed for aged care centers with multiple rooms and a joint attic. Its predictions obey reasonably well with the numerical results. Solar chimney’s viability in aged care center is confirmed as a 7.22 air change per hour (ACH) ventilation can be achieved even under a low solar radiation intensity of 200 W/m2, where its performance fulfills the minimal ventilation requirement (i.e., 6 ACH) suggested by the WHO for airborne infection isolation rooms. This study offers a new design and a guideline for the future implementation of solar chimney in aged care centers or similar facilities.

Development of exergy maps as a tool for assessing solar energy potential in Iraq

This work aims to develop three sets of maps: solar intensity, solar exergy, and the exergy efficiency of the solar and PV systems for Iraqi cities. Petela mode equations were programmed depending on the Iraqi weather data and solved using the Engineering Equation Solver software. It is found that the western regions of Iraq, which are often desert lands, suffer from the low intensity of solar radiation due to the dusty weather that characterises this region. The solar exergy is 70 W/m2 to 138 W/m2 in January, and the range in July is 260 W/m2 to 330 W/m2. The higher average exergy efficiency ranges from 15% to 19.3% in the winter, while the lower is 7.5% to 13.8% in the summer. Finally, the sites at lower latitudes have more global solar radiation. On the other hand, higher latitudes have more exergy efficiency than those at lower latitudes.

Wintertime subarctic new particle formation from Kola Peninsula sulfur emissions

Abstract. The metallurgical industry in the Kola Peninsula, north-west Russia, form, after Norilsk, Siberia, the second largest source of air pollution in the Arctic and subarctic domain. Sulfur dioxide (SO2) emissions from the ore smelters are transported to wide areas, including Finnish Lapland. We performed investigations on concentrations of SO2, aerosol precursor vapours, aerosol and ion cluster size distributions together with chemical composition measurements of freshly formed clusters at the SMEAR I station in Finnish Lapland relatively close (∼ 300 km) to the Kola Peninsula industrial sites during the winter 2019–2020. We show that highly concentrated SO2 from smelter emissions is converted to sulfuric acid (H2SO4) in sufficient concentrations to drive new particle formation hundreds of kilometres downwind from the emission sources, even at very low solar radiation intensities. Observed new particle formation is primarily initiated by H2SO4–ammonia (negative-)ion-induced nucleation. Particle growth to cloud condensation nuclei (CCN) sizes was concluded to result from sulfuric acid condensation. However, air mass advection had a large role in modifying aerosol size distributions, and other growth mechanisms and condensation of other compounds cannot be fully excluded. Our results demonstrate the dominance of SO2 emissions in controlling wintertime aerosol and CCN concentrations in the subarctic region with a heavily polluting industry.

Assessment Model Impact of Climate Change on Potential Production for Food and Energy Needs for the Coastal Areas of Bengkulu, Indonesia

Bengkulu is said to be the center of the world's climate because of the influence of water conditions and the topography of the area where the rain cloud formation starts. The waters in Bengkulu Province become a meeting place for four ocean currents which eventually become an area where the evaporation process of forming rain clouds becomes the rainy or dry season and affects the world climate. Method to analyze descriptively, shows oldeman Classification and satellite rainfall estimation data is added. In relation to the Analysis of Potential Food Availability for the Coastal Areas of Bengkulu Province uses a quantifiable descriptive analysis method based. The results show that most are included in the Oldeman A1 climate zone, which means it is suitable for continuous rice but less production due to generally low radiation intensity throughout the year. In an effort to reduce or eliminate the impact of climate change on food crop production, it is necessary to suggest crop diversification, crop rotation, and the application of production enhancement technologies. Strategies in building food availability as a result of climate change are: First, develop food supplies originating from regional production and food reserves on a provincial scale. Second, Empowering small-scale food businesses which are the dominant characteristics of the agricultural economy, especially lowland rice and horticultural crops. Third, Increase technology dissemination and increase the capacity of farmers in adopting appropriate technology to increase crop productivity and business efficiency. Four, Promote the reduction of food loss through the use of food handling, processing and distribution technologies.

X-ray radiation monitor for measuring solids content in fluid fine tailings.

The extraction of bitumen from oil sands produces fluid fine tailings (FFT) consisting mainly of water, sands, clay, and residual bitumen. Generally, devices with radioactive sources are used to measure the variation of FFT density or solids concentration inline, but to date there is no suitable device for in situ monitoring in tailings storage facilities such as large tailings ponds. In this study, an alternative method using high-resolution spectrometry based on a low radiation intensity source and a cadmium telluride (CdTe) detector was used to measure the solids content in tailings samples based on X-ray attenuation. The radiation source used in the experiment was a 1 μCi 133 Ba. GEANT4, a Monte Carlo-based simulation code that calculates the transmission of radiation through matter, was used to simulate the results of this study and build calibration curves that can determine the solids content concentration based on measured sample composition. Experiments and simulations were performed on various concentrations of both actual FFT samples from tailings facilities and kaolin as a model material. Good agreement between the experimental and simulation results was observed, paving the way for a potential real-time solids content measurement system that could be deployed over large areas to measure the settling of FFT in tailings ponds.

Experimental study on solar air heater with encapsulated phase change material on its absorber plate

AbstractEffective usage of solar air heaters (SAH) is limited to specific time due to nonavailability and low intensity of solar radiation. In addition, SAH suffers from lower thermal efficiencies. Encapsulated phase change material (PCM) on absorber plate of SAH is one of the passive techniques to improve thermal efficiency of SAH as well as to extend its application to nonsunshine hours. In this article, capsules of circular and square cross sections filled with PCM were used on absorber plate of a double pass counter flow SAH and SAH efficiency was experimentally determined. Capsules were placed in inline and staggered grid arrangements perpendicular to the flow direction of the air and paraffin wax was used as the PCM. Experiments were conducted each day in two cycles (charging PCM from 10:00 am to 2:00 pm and discharging PCM from 4:30 pm to 5:30 pm), with fixed mass flow rate of air in between 0.00879 and 0.01484 kg/s. It is found from the results that, efficiency of SAH with square staggered encapsules is at an average of 15.8% higher than the remaining arrangements. During PCM discharge, air temperature at the SAH exit was at an average of 5.17°C greater than ambient temperature for all arrangements.

Experimental study and economic cost analysis about enhancement productivity for a conventional solar still combined with humidifiers ultrasonic

ABSTRACT This work investigates and compares the yield of distillate water and economic feasibility of two types of solar stills, namely the conventional solar still (CSS) and the suggested solar still (SSS). Both the solar stills (CSS and MSS) were identical in dimensions and under the same operating conditions to facilitate comparison of the thermal performance. An hourly daily production analysis was performed for both models together with the detailed analysis to assess the annual cost of producing a liter of distilled water. The purpose of the present work is to overcome the relatively low productivity issues of conventional solar stills and excessive fog from humidifiers ultrasonic during low solar radiation intensity hours. Therefore, the suggested solar still (SSS) was augmented by humidifiers ultrasonic devices inside the basin water solar still, and covering it with a cotton cloth cover, to increases the evaporation surface area, reducing the distinctive dimension and not allowing the generated fog to spread even in cases of low solar radiation and the most important is increased the distilled daily water productivity in comparison with conventional solar still. The results reveal that the suggested solar still (SSS) has a daily yield higher than of CSS by 68%, SSS thermal efficiency reached 1.1 times (110%) in comparison with CSS at 4:00 pm. The proposed improvement has reduced the cost of producing a liter of distillate water by 34.9% compared to CSS. To verify the importance of the suggested solar still, a comparison was conducted with the previous studies in terms of the cost of producing a liter of distilled water. The analysis of the results revealed that there is an appropriate agreement between the previous works and the suggested solar still in the current work.

Effects of reduced solar radiation on photosynthetic physiological characteristics and accumulation of secondary and micro elements in paddy rice.

Atmospheric haze pollution is a popular environmental issue in recent years. The aerosols reduce solar radiation reaching land surface, with consequences on the growth of crops. In order to examine the effects of low solar radiation intensity on the physiological characteristics and mineral nutrition of grain crops, the random designed field experiment of rice cultivar 'Nanjing 5055' planted under different shading degrees (CK, natural sunlight control; Y1 and Y2 were treatments with shading rates of 19% and 45%, respectively) were conducted. The response of chlorophyll content (SPAD), leaf area index (LAI), net photosynthetic rate of leaves, grain yields and secondary/micro element contents (Ca, Mg, Fe, Zn, Mn, Cu) in rice were measured during key growth stages (jointing, heading, and grain filling stages). Results showed that, shading treatments inhibited the synthesis of photosynthetic products and reduced the LAI during the whole growing period, but at the early stage it did not affect the chlorophyll content, which was significantly increased at the late growth stage. Compared with CK, the 1000-grain weight of rice was decreased by 14.4% and 18.4%, and seed setting rate was decreased by 4.3% and 12.9%, which resulted in rice yield reduction. With the increases of shading rates, rice yield was decreased by 58.5% and 66.4%, respectively. The nutrient concentrations, especially for the micro-elements, in brown rice and glume were increased. Shading had a negative effect on rice growth, which would eventually reduce the crop production. The higher contents of heavy metals such as Cu and Mn would be a pollution risk for human health. Therefore, the impacts of weakened solar radiation on quantity and quality of crops need comprehensive evaluation.

Physiological potential of wheat seeds produced under light restriction

The low radiation intensity can negatively affect the production of photoassimilates in plants for allocation and synthesis of reserves into seeds. This study aimed to evaluate the physiological quality of wheat seeds produced by plants imposed on conditions of light reduction in different phenological stages, remaining until the end of the cycle. The experiment was carried out in a greenhouse in 2018, with a completely randomized design, with 11 treatments and 20 repetitions. The treatments consisted of 11 seed lots: 10 of plants grown in artificial shade (70%) started in the Zadoks code’s phenological stages: 23; 30; 35; 45; 55; 60; 65; 70; 75; 80 and control lot (without shading). The seeds were analyzed for germination and vigor. Seed germination was not affected. There was a reduction in vigor through the tests of accelerated and cold aging when the shading started between stages 55 and 65, but with a minimum vigor of 93 and 94%, respectively. It is concluded that the restriction of light during the development of wheat plants does not affect the germination of the seeds produced but impairs the vigor mainly when imposed in the reproductive phases.

Impacts of the PAH size and the radiation intensity on the IR features of illuminated dust within the reflection nebulae

Interstellar dust grains are illuminated in the reflection nebulae. Under conditions of the PAH size and the intensity of the interstellar radiation field, we follow their impact on the PAH aromatic infrared bands using the numerical DustEM code. For a dust model consisting of PAH, amorphous C and amorphous silicate, the PAH size varies in a range from 0.31 to 4.9 nm while the radiation intensity varies by a scale factor from 0.1 to 10 4 . Various trends of the results show the effect of varying both the PAH size and the radiation intensity on the strength of the aromatic mid-IR bands. Through small PAH sizes less than 0.7 nm, the grain temperature distribution of PAHs shows a small variation within 2–3 K at low radiation intensity while it increases to 15 and 8 K for PAH 0 and PAH + , respectively, at higher radiation intensity. In final the variability in these results reveals the evolution of the dust grains under the physical space conditions of the reflection nebulae. In the mid-IR region, the contributions of PAH 0 and PAH + in the total SED intensity agree with the proportions of these PAHs observed in some reflection nebulae having higher radiation intensities.

Effects of Radiation Intensity, Mineral Matrix, and Pre-Irradiation on the Bacterial Resistance to Gamma Irradiation under Low Temperature Conditions.

Ionizing radiation is one of the main factors limiting the survival of microorganisms in extraterrestrial conditions. The survivability of microorganisms under irradiation depends significantly on the conditions, in which the irradiation occurs. In particular, temperature, pressure, oxygen and water concentrations are of great influence. However, the influence of factors such as the radiation intensity (in low-temperature conditions) and the type of mineral matrix, in which microorganisms are located, has been practically unstudied. It has been shown that the radioresistance of bacteria can increase after their exposure to sublethal doses and subsequent repair of damage under favorable conditions, however, such studies are also few and the influence of other factors of extraterrestrial space (temperature, pressure) was not studied in them. The viability of bacteria Arthrobacter polychromogenes, Kocuria rosea and Xanthomonas sp. after irradiation with gamma radiation at a dose of 1 kGy under conditions of low pressure (1 Torr) and low temperature (−50 °C) at different radiation intensities (4 vs. 0.8 kGy/h) with immobilization of bacteria on various mineral matrices (montmorillonite vs. analogue of lunar dust) has been studied. Native, previously non-irradiated strains, and strains that were previously irradiated with gamma radiation and subjected to 10 passages of cultivation on solid media were irradiated. The number of survived cells was determined by culturing on a solid medium. It has been shown that the radioresistance of bacteria depends significantly on the type of mineral matrix, on which they are immobilized, wherein montmorillonite contributes to an increased survivability in comparison with a silicate matrix. Survivability of the studied bacteria was found to increase with decreasing radiation intensity, despite the impossibility of active reparation processes under experimental conditions. Considering the low intensity of radiation on various space objects in comparison with radiobiological experiments, this suggests a longer preservation of the viable microorganisms outside the Earth than is commonly believed. An increase in bacterial radioresistance was revealed even after one cycle of irradiation of the strains and their subsequent cultivation under favourable conditions. This indicates the possibility of hypothetical microorganisms on Mars increasing their radioresistance.

Optimal site selection for the installation of solar PV plants: a case study in Nakhchivan Ar, Azerbaijan

Since the electrical power produced by converting total solar radiation on a horizontal surface, composed of direct and diffuse components of PV cells, has low output power, it is necessary to identify areas with high power factor for more efficient power generation. However, due to the low efficiency of PV panels (14-18%) and the low intensity of total solar radiation on a horizontal surface, large installation space is required to achieve a certain power level. Due to the high cost of installing solar power plants, a comprehensive systematic assessment of the geographic factors of the region is required to select the most suitable location. The reason we chose Nakhchivan as the study area is that the radiation level is high compared to other regions of Azerbaijan (1220-1699 kWh/m2-year), and the number of hours of sunshine per year exceeds 2500. Since the creation of solar power plants in regions with high values of the total radiation on a horizontal surface depends on technical, economic and environmental criteria, descriptive criteria are used to determine the optimal areas. The analytical hierarchy process model, based on multi-criteria decision-making methods, was used to identify suitable locations for solar power plants. In the first phase of the study, seven criteria were analysed to determine suitable locations: Total solar radiation on a horizontal surface, slope, and land use, buffer distance from areas with high annual solar energy potential to residential areas, proximity to substations, highways, and power lines. At the second stage, the level of accessibility and suitability of areas within the framework of certain criteria was determined using the weighted overlay tool in geographic information systems. At the second stage, using the weighted overlay tool in GIS, the level of suitability of territories was determined according to certain criteria. As a result, the study, it was concluded that 9.5% (510 km2) of the land of Nakhchivan have high suitability, 12% (645 km2) - average suitability and 24% (1290 km2) - low suitability for placing solar power plants. The remaining 54.5% (2930 km2) of the region belongs to the territories that are not suitable for use due to low radiation, high slope, the presence of protected areas, settlements, agricultural areas and poorly developed infrastructure. Optimal locations cover mainly the southern and eastern parts of the region, as shown in the polygon shape on the suitability map.   The electricity generated by converting full solar radiation to the horizontal surface consists of direct and diffuse components of PV cells, which, due to their low output power, can be used in areas with high energy efficiency for efficient power generation. &nbsp

Assessing the mechanisms underlying sunflower grain weight and oil content responses to temperature during grain filling

Temperature and solar radiation during grain filling are the main drivers of grain weight and composition in several crops. While significant progress has been done on the effect of solar radiation intercepted by the plants (ISR) on grain weight (GW, mg) and oil content (OC, mg grain−1) of sunflower (Helianthus Annus L.), the effects of temperature on these traits are far from clear. As temperature affects the rate of plant development, increasing temperature would shorten grain filling duration and so, the critical period for ISR effect on GW and OC (indirect effect of temperature). However, direct effects of temperature non-mediated by ISR accumulation could also affect these traits. The objectives of this work were a) to characterize the responses of grain weight and oil content to mean temperature during grain filling in two traditional sunflower hybrids and b) to determine whether these responses can be exclusively explained by changes in ISR or any direct effect of temperature should also be considered. Two experimental approaches have been used to address these objectives: i) temperature manipulation at constant incident radiation in growth chambers; ii) modification of radiation interception in the field in different locations and years (different mean temperatures). Growth chamber experiments showed that GW and OC respond to temperature in a plateau lineal shape. At low incident radiation such as that of growth chambers, temperature effects on GW can be exclusively explained by reductions in ISR, while both direct and indirect effects of MT are evident on OC. Results obtained in field experiments confirmed this behavior at low radiation. Both GW and OC exponentially increased up to a maximum with ISR disregarding MT. Mathematical models were established to describe the responses of GW and OC to MT and ISR. These models consider MT x ISR interactive effects on GW; and MT - ISR additive effects on OC. The combination of growth chamber and field experiments observations allowed to unravel different mechanisms underlying the responses of GW and OC to temperature: at low incident radiation intensity, increasing temperature decreased GW exclusively by reducing ISR accumulation (indirect effects) while at higher radiation, temperature displays both direct (non-mediated by ISR) and indirect (ISR mediated) effects on GW. OC is affected by temperature in both direct and indirect way disregarding ISR. This work constitutes an important contribution towards understanding the effect of temperature during grain filling on sunflower yield and its relationship to solar radiation effects.

Electrical Modelling of Switching Arcs in a Low Voltage Relay at Low Currents

The arc behaviour of short, low current switching arcs is not well understood and lacks a reliable model. In this work, the behaviour of an arc in the air is studied during contact separation at low DC currents (0.5 A to 20 A) and for small gap lengths (0 mm to 6 mm). The experiments are performed on a low voltage relay with two different electrode configurations. The arc voltage is measured during the opening of the contacts at constant current. The arc length is determined optically by tracing the mean path of the arc over time from a series of high-speed images. From the synchronised data of voltage vs. distance, first a sudden jump of the voltage at the start of contact opening is observed. Secondly, a sudden change in the voltage gradient occurs as the arc is elongated. Short arcs with a length up to approximately 1.25 mm show an intense radiation in the overall gap region and high voltage gradients. An unexpected behaviour never reported before was observed for longer arcs at low current: Two characteristic regions occur, a region in front of the cathode, with a length of approximately 1.25 mm, having an intense radiation and a high voltage gradient as well as a region of much lower radiation intensity and a comparatively lower voltage gradient in the remaining gap area despite a small anode spot region. The characteristic border of approximately 1.25 mm is almost independent of the current. A generalised arc voltage model is proposed based on the assumption that a constant sheath voltage and two discrete field regions exist, which are modelled as two independent linear functions of voltage vs. length. The data for various currents is combined to yield a general non-linear function for predicting the arc voltage vs. arc length and current.

Pengaruh Cara Pengeringan Gabah terhadap Mutu Fisik, Fisikokimia, dan Organoleptik Beras Varietas Unggul Padi

Rice grain drying using sun radiation has its problem during the rainy season, due to low radiation intensity. Box dryer using gas as its source of energy had been developed to overcome the problem during the rainy season. This research was aimed to study the effect of drying methods on physical, physicochemical, and organoleptic quality of some improved rice varieties. Seed of five rice varieties, namely Ciherang, Inpari 30, Inpari 32 (white grain rice), Inpari 24 and Inpago 7 (red grain rice), were planted at Sukamandi Research Station, Indonesian Center for Rice Research, following the Integrated Crop Management approach. The rice crops were harvested when the grain had ripen optimally, threshed using a threshing machine and the grains were dried using a box type dryer and using the sun radiation. The milled rice was analyzed for their physical, physicochemical, and organoleptic quality. Results showed that the differences of drying methods, namely sun-drying and box drying, affected the physical quality of rice grain. Box dryer for Ciherang variety yielded higher percentage of unpolished milled rice and the head grain rice was slightly higher than that of sun-drying. However, drying methods did not affect the physicochemical and organoleptic quality of the cooked rice. Box dryer is considered suitable for rice grain drying during the rainy season.

Winter temperature measurements in a composite girder segment

This article presents experimental results from a concrete-steel composite girder. The girder is composed of an I-shape steel beam that is topped by a reinforced concrete slab. The girder was constructed in an open environment so that it is freely subjected to the variation of the atmospheric thermal loads. These loads include the solar radiation, temperature of the surrounding air and speed of the wind. Therefore, a weather station that includes sensors to measure the three aforementioned thermal loads was installed beside the girder. The girder was instrumented with thermocouples that were either embedded in the concrete slab or attached to the steel beam. The thermocouples were distributed across the slab thickness, along its width and along the vertical centerline of the composite girder. The aim of this research is to provide experimental measurements that facilitate better understanding of temperature gradient distributions in composite bridge girders in winter. The test records were continued for approximately two months during the cold season. The test results showed that the negative vertical temperature gradient was higher than the corresponding positive one due to the low intensity of solar radiation. Similarly, the lateral positive temperature gradient along the width of the concrete slab was higher than the vertical positive temperature gradient due to the low altitude of solar radiations.

Increased 25(OH)D3 level in redheaded people: Could redheadedness be an adaptation to temperate climate?

About 1-2% of European population are redheaded, meaning they synthesize more pheomelanin than eumelanin, the main melanin pigment in humans. Several mutations could be responsible for this phenotype. It has been suggested that corresponding mutations spread in Europe due to a founder effect shaped either by a relaxation of selection for dark, UV-protective phenotypes or by sexual selection in favour of rare phenotypes. In our study, we investigated the levels of vitamin D precursor 25(OH)D3 (calcidiol) and folic acid in the blood serum of 73 redheaded and 130 non-redheaded individuals. In redheaded individuals, we found higher 25(OH)D3 concentrations and approximately the same folic acid concentrations as in non-redheaded subjects. 25(OH)D3 concentrations correlated with the intensity of hair redness measured by two spectrophotometric methods and estimated by participants themselves and by independent observers. In non-redheaded individuals, 25(OH)D3 levels covaried with the amount of sun exposure and intensity of suntan while in redheaded individuals, this was not the case. It suggests that increased 25(OH)D3 levels in redheaded individuals are due to differences in physiology rather than in behaviour. We also found that folic acid levels increased with age and the intensity of baldness and decreased with the frequency of visiting tanning salons. Our results suggest that the redheaded phenotype could be an evolutionary adaptation for sufficient photosynthesis of provitamin D in conditions of low intensity of UVB radiation in central and northern parts of Europe.