Maximum Irradiance Research Articles

Safety Analysis of Long-Range and High-Power Wireless Power Transfer Using Resonant Beam

Resonant Beam Charging (RBC) is a promising Wireless Power Transfer (WPT) technology to realize long-range and high-power charging for electronic devices. However, the safety mechanism of the RBC system has not been investigated so far. In this paper, we propose an analytical model based on electromagnetic field analysis for evaluating the performance of the RBC system with external object invasion, such as the benchmark for the WPT safety, irradiance on the invading object. For the RBC system with $\text{5}\;$ m transmission distance and $\text{1}\;$ W output electric power, the safety numerical analysis of radiation illustrates that the maximum irradiance on the invading object is $\text{0.81}\;\text{W/cm}^2$ , which is approximately $1/10$ compared with $ \text{8.22}\;\text{W/cm}^2$ for the comparable laser charging system. Particularly, the peak irradiance on the invading object of the RBC system satisfies the Maximum Permissible Exposure (MPE) requirement for human skin, which is $\text{1}\;\text{W/cm}^2$ in the standard “Safety of Laser Products IEC $60825-1$ ”. Hence, the RBC system can realize skin-safe WPT with Watt-level power over meter-level distance.

Tolerance to light of patients suffering from infectious keratitis

AbstractPurposeWith very photophobic patients, the advantages of red or near infrared (NIR) light to develop new ophthalmology imaging devices seem obvious: no or little glare, possibility of long signal integration, no phototoxicity, and lesser autofluorescence of ocular tissues. Nevertheless, in this range, the shortest possible wavelength facilitates signal detection.AimTo determine the maximal irradiance tolerated with 6 wavelengths: 2 red, 2 far red and 1 NIR lights in order to determine the shortest wavelength well tolerated by patients, in comparison with the standard cobalt blue light of ophthalmology slit lamp.MethodsStudy design: interventional, monocentric, single group assignment study on 30 eyes of 30 patients with infectious keratitis after informed consent. Thanks to a customized machine from our laboratory, the photophobic eye was exposed to the 6 lights with increasing intensity. The patients switched off the light when the discomfort was too elevated. The maximal cumulative irradiance possible at 482, 650, 675, 700, 750 and 800 nm were respectively 171, 689, 759, 862, 920 and 889 mW/cm2.ResultsThe maximal cumulative irradiance tolerated increased significantly with wavelength (p < 0.001). However, the difference was not significant between each increment. Thus, red at 675 nm gave a significantly higher cumulative irradiance than blue at 482 nm. Red at 700 nm did not provide significant gain; however, far red at 750 nm still provided additional gain, but not at 800 nm. The shortest wavelengths were stopped more quickly and more than 50% of patients reached the maximum irradiance delivered by the source at 750 and 800 nm.ConclusionsWe demonstrate that a light source at 750 and 800 nm can be used for ophthalmic imaging with good tolerance in the photophobic patient.

Maximal Selective Transmit Diversity for Petahertz Wireless Communications With Continuous Waveform Detector

Motivated by unique atmospheric scattering properties of optical waves at petahertz frequencies, we present a novel maximal selective transmit diversity scheme based on the selection of maximum irradiance optical path with a continuous waveform detector employed for petahertz wireless communications. The proposed scheme is designed to significantly improve the performance of a non-line-of-sight (NLOS) petahertz link in a turbulence-induced fading channel. We characterize the received signal by a continuous wave detector and quantify the cumulative distribution function (CDF) of the largest order statistics of the received irradiance. Furthermore, we derive closed-form expressions of important performance metrics including the average bit error rate, the outage probability, and the optical channel capacity with each scattered path experiencing the Gamma-Gamma distributed turbulence-induced fading. From the analytical expressions derived, the performance of the proposed NLOS petahertz communication system is analyzed and validated. Simulation results show that the proposed scheme effectively overcomes the channel impairment without increasing the transmit power. Even under strong turbulence fading, when the number of transmit diversity branches increases from 1 to 2 and 4, the required average signal-to-noise ratio (SNR) to maintain an outage probability of 10−5 is found to be significantly reduced by 13 dB and 21 dB, respectively.

Improved Pyramid Solar Still for Solar Water Desalination – A Case Study

Solar energy is considered as an available source of huge amount of thermal energy with low cost and it is environmentally friendly. Seawater desalination is the main source of freshwater in many countries using different technologies. Seawater desalination using solar thermal energy with passive techniques is vital for arid areas that have shortage in electricity grids or any other sources of energy. In this study, an experimental investigation for a solar still with pyramidal cover in the environmental conditions of arid regions in Saudi Arabia has been conducted. The pyramid surfaces have been designed and directed so that one of the faces receives sunlight directly for a period, which helps in the process of evaporation faster, and the other interface is away from the rays so that the temperature is low to help in the process of condensation of steam. In addition, a seawater feeding system is designed to maintain a constant level of water height within the basin. The accumulated freshwater productivity along sun shining period of the day has reached 3230 gm and the instantaneous productivity takes place at the maximum irradiance period and it has reached 472 gm. The energy and the exergy analyses for the system have indicated that the energy and the exergy efficiencies of the system have reached a maximum of 60% and 5%, respectively. The over day energy and exergy efficiencies of the system have been 31.6% and 2.35%, respectively. The produced freshwater cost from the system has been found out to be 0.1 $/L/m2.

Optimal operation of photovoltaic/diesel generator/pumped water reservoir power system using modified manta ray optimization

Abstract To fully utilize the renewable energy sources and increase the power system reliability with high penetration of renewable energy sources, hybridization with other renewable or nonrenewable sources as well as energy storage systems is highly recommended. This paper studies a hybrid power system consisting of solar panels, a diesel generator, and a pumped water reservoir. In this system, the excess solar energy is used to pump the water into the water storage for later use. When solar energy is not enough to supply the demand, diesel generation and pumped water reservoir help supply the demand. Due to the nonlinear nature of fuel consumption of diesel generator, an optimum amount of power generated by this unit can lead to cost-saving. This leads to an optimization problem, which is solved by an optimization technique proposed in this paper. The optimization used is named manta ray optimization and is based on the improved version of the manta ray foraging technique. The simulation results obtained from the proposed technique, the conventional manta ray foraging technique, and other well-known techniques are compared to the proposed method to prove better performance and robustness of the proposed method. Three scenarios are analyzed here which are associated with high, normal, and low solar radiation, which are respectively related to maximum, average, and minimum solar irradiance in the studied year. In the case of low solar radiation, optimization is not required as DG is the only auxiliary generation unit. The fuel consumptions using the proposed optimization technique are averagely 6.14% and 5.96% better in scenarios 1 and 2, respectively. Moreover, the robustness achieved by this optimization method is 17.94% and 48.41% higher in scenarios 1 and 2, respectively.

DETERMINATION OF THE INFLUENCE OF THE PHASE COMPOSITION OF Cu-Bi COATINGS ON THE EFFICIENCY OF SHIELDING FROM IONIZING RADIATION.

The work is devoted to the study of the efficiency of shielding the radiation exposure of heavy ions depending on the phase composition of Cu-Bi coatings. As a method of producing protective coatings, an electrochemical deposition method was used. The change in phase composition was carried out by varying the applied potentials difference during deposition. The study found that the change in phase composition leads to an increase in coating density, as a result of the dominance of the CuBi2O4 phase and an increase in the structural ordering degree. During shielding efficiency tests, it was found that the greatest decrease in the degree of crystallinity is observed for copper coatings, for which the amorphization of the structure at the maximum irradiation fluence didn’t exceed 12 %, while for coatings based on CuBi2O4 the value of amorphization was no more than 1.2 % of initial value. Amorphization and fragmentation of grains at high radiation doses leads to a decrease in the shielding efficiency, as well as an increase in the value of the deviation ΔU.

Beam propagation simulations for LISA in the presence of telescope aberrations

Accurate simulation of the propagation of light between the spacecraft of the laser interferometer space antenna (LISA) gravitational wave observatory will be a vital tool in determining the optical design of the telescopes used in the constellation. In this work, we examine the methods available for numerical simulation of this propagation, and consider the effect of an aberrated transmitting telescope (Tx) on the light collected by the receiving telescope (Rx). Propagation software has been developed using direct numerical integration methods, and has been validated by comparison to analytical solutions for particular cases. Zernike modal aberrations up to and including primary spherical have been considered in the Tx, and, in particular, the effects of defocus, astigmatism and coma were examined. It was found that minimization of the even radial order aberrations in Tx resulted in a reduced wavefront error at Rx, while odd aberrations such as coma can displace the maximum irradiance away from the optical axis. Thus careful consideration of the impact of telescope aberrations will be required to minimise detrimental effects on the detection of gravitational waves.

Real Time Monitoring System Dari Active Solar Photovoltaic Tracker Berbasis Internet Of Things

Abstract: This monitoring system is used to monitor currents and voltages from Solar Power Plants (PLTS) with solar cell capacities of 50WP, 80WP, and 100WP. PLTS used is an active type of solar tracker, where solar cells used can find the maximum solar irradiation position by determining the upper and lower voltages as the reference voltage in the Arduino program. After PLTS can produce energy, then the energy can be used to turn on AC and DC electrical loads. From the energy used, here of course there are currents and voltages starting from the output of the solar cell, the accumulator output, the input at the AC load, and the input at the DC load. The monitoring results that have been carried out subsequently will be automatically sent to the Thingspeak application by using the SIM800L Module. This thingspeak application will send data in the form of numbers and graphs in real time. By comparing the value of the measurement results on Arduino and the thingspeak application, we get the size of the percentage of reading errors on the measuring instrument.

Tolerance to Light of Patients Suffering From Infectious Keratitis.

With very photophobic patients, the advantages of red or near infrared light to develop new ophthalmology imaging devices seem obvious: no or little glare, possibility of long signal integration, no phototoxicity, and lesser autofluorescence of ocular tissues. Nevertheless, in this range, the shortest possible wavelength facilitates signal detection. The aim of this study was, thus, to determine the maximal irradiance tolerated with 6 wavelengths: 2 red, 2 far red, and 1 near infrared lights to determine the shortest wavelength well tolerated by patients, in comparison with the standard cobalt blue light of ophthalmology slitlamp. An interventional, monocentric, single-group assignment study was conducted on 30 eyes of 30 patients with infectious keratitis. Thanks to a customized machine, the photophobic eye was exposed to the 6 lights with increasing intensity. The patients switched off the light when the discomfort was too elevated. The maximal cumulative irradiance possible at 482, 650, 675, 700, 750, and 800 nm were 171, 689, 759, 862, 920, and 889 mW/cm, respectively. The maximal cumulative irradiance tolerated by patients increased significantly with wavelength (P < 0.001), but the difference was not significant between each increment: red at 675 nm gave a significantly higher cumulative irradiance than blue at 482 nm; red at 700 nm did not provide significant gain compared with 675 nm; and far red at 750 nm still provided additional gain compared with 700 nm, but no significant gain was observed between 750 and 800 nm. The shortest wavelengths were stopped more quickly, and more than 50% of patients reached the maximum irradiance delivered by the source at 750 and 800 nm. We demonstrate that a light source at 750 and 800 nm can be used for ophthalmic imaging with good tolerance in photophobic patients. NCT03586505.

Assessment of WWER-1000 Core Baffle Form Alteration during Operation

The paper illustrates the results of the computer assessment of the form alteration in WWER-1000 core baffle obtained via the solution to the coupled thermoelastoplastic task considering the strains of irradiation growth and creep. In the modeling of the contact conditions, the temperature redistribution is considered due to the incompliance of the coolant flow in the contact zone between the core baffle and in-vessel core barrel with the design conditions. The modern approaches to the modeling of strains of the irradiation growth and irradiation creep in austenite steels are used in the space-limited environment under neutron exposure and elevated temperature. The finite element analysis involves the mixed scheme of the finite element method, which allows determination of the stress-strain state with high accuracy. The calculations are performed in the two-dimensional statement for the cross-section of the core baffle with the maximum damaging dose and irradiation temperature under the condition of the generalized plane strain. The results of the calculations are presented for full-scale reactor operation and scheduled shutdown to recharge the fuel cluster at the end of core life. The data on the distribution and value of the gap between the core baffle and barrel, as well as the spacer grids of the edge fuel assemblies and reactor core baffle edges, have been obtained from the median values of the dose dependence on swelling at different temperatures in Kh18N10T austenite steel.

Designing and analysis of the micro-trigeneration systems based on combined proton exchange membrane fuel cell with photovoltaic and photovoltaic/thermal prime movers in portable applications

Developing micro-trigeneration systems is an important step in military applications. Therefore, suggesting new portable trigeneration systems that use several energy sources is necessary. The importance of the issue is enhanced when renewable energy sources are used in suggested systems for places with no accessibility to energy sources. In this paper, different useful micro-personal trigenertion systems are proposed based on photovoltaic/thermal (PVT) and combination of photovoltaic (PV) with proton exchange membrane fuel cell (PEMFC). The proposed systems are designed to provide all or a part of personal demand loads by photovoltaic phenomena. Using different energy sources such as solar and hydrogen electrochemical energies in the proposed systems increases the flexibility and reliability of the system. The trigeneration performance of suggested cycles is simulated in the engineering equation solver software (EES) and the results based on different prime movers are compared with the system based on ultra-micro gas turbine (UMGT), which was studied in the previous work under extremely cold/hot weather. Although utilizing the PV module and PVT collector improves the performance of the system, it increases its weight as well, which is not suitable in portable applications. Therefore, the size of elements must be selected carefully. Results showed that the system based on PVT generated more power in summer so that the maximum of 105 and 17 W electrical power were generated with overall efficiency of 14% and 9% in summer and winter at maximum solar irradiance respectively. In addiotion, the most efficient system was the system based on UMGT in which the maximum overall efficiency was 21% and 28% in summer and winter respectively. The effects of the water mass flow rate of PVT on power and overall efficiency were investigated too. We found that increasing in mass flow rate increases the power and overall efficiency slightly about 16% and 15% in summer and about 33% and 25% in winter respectively. Additionally, results showed that in the combined PV-PEM system, the PV module decreased the aluminum hydride consumption significantly and generated a maximum of 13.5 W electrical power in summer. The weight of the suggested trigeneration systems is different based on different prime movers and varies from 5.66 kg to about 37.5 kg for single PEM and PVT systems respectively.

Comparison of GOME-2 UVA Satellite Data to Ground-Based UVA Measurements in South Africa.

Satellite estimates of surface ultraviolet A (UVA) (315-400nm) from the Global Ozone Monitoring Experiment (GOME)-2 were compared to ground-based measurements at four stations in South Africa for 2015. The comparison of daily exposure and daily maximum irradiance was completed for all-sky and clear-sky conditions. There is a strong linear correlation between the satellite and ground-based data with a correlation coefficient (r) between 0.86 and 0.97 for all-sky conditions. However, at three of the stations the satellite data are underestimated compared to ground-based data with a mean bias error (MBE) between -8.7% and -20.6%. A seasonal analysis indicated that there is a link between the bias in ground-based and GOME-2 UVA and cloud fraction. Factors such as aerosols, surface albedo, altitude and data resolution may contribute to the underestimations found at the three sites. These results indicate that satellite estimates of surface UVA over South Africa do not exhibit the same behavior as other stations around the world and therefore require further validation.

The effect of device position and use of transparent covers on the irradiance distribution of LED phototherapy devices

Background. Effective phototherapy reduces neonatal jaundice and its complications. Irradiance increases as the distance of the light source decreases from a single phototherapy light. There are limited studies of the effect of distance and positional changes on different light-emitting diode (LED) light designs on achieving effective phototherapy. Objectives. To describe and compare the effect of distance, angle and plastic barriers on three different LED lights of different design. Methods. Comparisons were made using a Servolite, a General Electric (GE) Lullaby and a Ningbo David LED phototherapy light. Measurements were done according to methods described by the International Electrotechnical Commission (IEC). The effective irradiated area was measured on a grid measuring 60 × 30 cm subdivided into 5 × 5 cm squares. Measurements were done for the following scenarios: light placed at the manufacturer’s recommended distance, 20 cm closer, 20 cm further, at an angle, through clear plastic and through scuffed Perspex. Results. When the lights were placed closer to the irradiated surface than the manufacturers’ recommendations, the maximum irradiance increased, but the median irradiance and uniformity ratio decreased. When the lights were angled at 45º, the median irradiance was decreased. A decrease in the median irradiance was also seen when phototherapy lights passed through scuffed plastic and food-grade plastic. Conclusion. Our study demonstrated that the placing of LED lights closer than the manufacturers’ recommendations, the use of transparent barriers and the use of lights at an angle, compromised phototherapy irradiance and distribution. Only the GE light met IEC standards.

The Prospects of Metal Oxide Nanoradiosensitizers: The Effect of the Elemental Composition of Particles and Characteristics of Radiation Sources on Enhancement of the Adsorbed Dose

Nanoparticles with a high atomic number are of interest as radiosensitizers for radiation therapy of cancer. A variety of nanoparticles and radiation sources makes the challenge of selecting their optimal combinations to achieve maximum irradiation efficacy relevant. In this work, we calculated the values of the dose enhancement factors of elemental compositions of metal oxide nanoparticles (Al2O3, TiO2, MnO2, Fe2O3 and Fe3O4, NiO, GeO2, ZrO2, CeO2, Gd2O3, Tm2O3, HfO2, Ta2O5, and Bi2O3), as well as GeO2 and HfO2 doped with the rare-earth elements lanthanum or ytterbium in combination with monochromatic photons (1–500 keV) and X-ray radiation corresponding to the radiation of kilovoltage X-ray therapy machines. At a nanoparticle concentration of 10 mg/mL, the maximum values of the dose enhancement factors were from 1.03 to 2.55 for monochromatic radiation and from 1.01 to 2.33 for the studied X-ray spectra. Doping GeO2 with 20% lanthanum or ytterbium led to an increase in the maximum value of dose enhancement factors by ~10%. Doping HfO2 did not lead to significant changes in the value of dose-enhancement factors. Thus, all studied elemental compositions of nanoparticles, with the exception of Al2O3 (a dose enhancement factor ~1.02), are promising for application in kilovoltage X-ray radiotherapy. At the same time, the complex dependence of dose enhancement factors on the spectral composition of X-ray radiation requires detailed studies of the impact of irradiation conditions on the magnitude of the radiomodifying effect of nanoparticles.

Studi Kelayakan Pemanfaatan Energi Matahari Sebagai Pembangkit Listrik Tenaga Surya Di Dusun Toalang

PLTS can be a solution that can be used to provide energy in the area provided far from the electricity network. This study aims to examine the feasibility of PLTS development in. Toalang Hamlet is one of the areas in West Kalimantan that has not been electrified, based on analysis in terms of geographical and demographic areas, has the potential to build PLTS. So to examine the feasibility of PLTS development the factors were collected and analyzed using PVSyst software. Of the several factors studied from the average air temperature between 21.0 to 35.4 degrees Celsius and the average humidity between 80% to 90%. Maximum irradiation at 11.00 a.m. and reached a value of 386 kWh / m 2 , and effective irradiation at the same time reached a value of 362 kWh / m2. The potential data of solar energy obtained from the measurement results with a pyranometer is 680 Watt / m 2 at 10:05 WIB using a solar meter measuring instrument. From the results of calculations and analysis using PVSyst software, what is concluded is; PLTS built in the area Centralized PLTS with Off Grid system which has a capacity of 21.84 kWp, load 55.758 Wh / day and Direction of solar panels to the south with a slope angle of 4 (four) degrees. Keywords: Feasibility Study , Renewable Energy, PLTS, PVsyst

Thermophysical properties and heating performance of self-healing asphalt mixture with fibres and its application as a solar collector

This paper presents the first analysis on the evaluation of the thermophysical and heating performance of self-healing asphalt mixtures with different contents of steel wool fibres for their potential use as a solar radiation absorbing material in an asphalt solar collector prototype. With this aim, four different dense-graded asphalt mixtures were prepared using the same aggregate gradation and bitumen content, but with different content of steel wool fibres: 0%, 2%, 4%, and 6% by total volume of bitumen. Physical and thermal properties, such as bulk density, air void content, thermal conductivity, specific heat capacity, and thermal diffusivity were evaluated on the asphalt test specimens. Steel wool fibre distribution inside the asphalt mixture samples was also evaluated by X-ray computed microtomography. Moreover, the thermal behaviour of a solar collector prototype, using an asphalt mixture with 4% of steel wool fibres as a solar radiation absorbing material was exposed to solar radiation conditions simulated in laboratory using a novel direct normal irradiance experimental model. This model was developed by the authors to experimentally simulate the maximum and minimum irradiance conditions for the city of Concepcion in Chile. The main results showed that self-healing asphalt mixtures with steel wool fibre addition reduced their thermophysical properties, explained by an increment in their total volume and due to the fibre distribution inside the samples. Additionally, this study proves that asphalt mixtures with 4% of steel wool fibres can be potentially used as a radiation absorbing material, transmitting the infrared radiation from the asphalt pavement surface to the water stored inside it. In short, this study provides the first assessment on the fundamental thermophysical variables of self-healing asphalt mixtures with metallic fibres, with the purpose of exploring their future use for energy harvesting applications.

Heavy-ion irradiation effects of Gd2Zr2O7 nanocrystalline ceramics as nuclear waste immobilization matrix

In this study, the irradiation response of Gd2Zr2O7 nanocrystalline ceramic was systematically studied under 5 MeV Xe20+ with radiation dose ranging from 2.6 dpa to 20.4 dpa. The grazing incidence X-ray diffraction (GIXRD) results demonstrate that the most severe irradiation area is located at a depth of about 180 nm under the maximum irradiation dose. The irradiated samples exhibit slight lattice expansion in the shallow superficial layer with maximum expansion ratio of 0.3% and corresponding amorphization rate of 62.2%. The Raman spectroscopy analysis show that there is a disorder in the local structure of Gd2Zr2O7 ceramics upon irradiation and the disorder increases with elevated radiation dose. FESEM-EDX indicates that the irradiation exhibits negligible effects on the elemental distribution. The HRTEM-SAED test confirms partial amorphization of the irradiated sample. Our work provides a detailed set of data for evaluating the radiation resistance of Gd2Zr2O7 nanocrystalline ceramics.

Special Features of Computational Assessment of the Change in Shape of WWER-1000 Reactor Core Baffle in View of Irradiation-Induced Swelling

Special features of computational assessment of dimensional change of WWER-1000 reactor core baffle during the reactor operation are discussed. The paper gives results of computational analysis of a change in shape of core baffle, which was performed by applying up-to-date approaches of modeling the irradiation-induced swelling of constrained austenitic steels under the action of neutron irradiation and elevated temperatures. The results have been obtained by using median and conservative values of parameters of the temperature and dose dependence of free swelling of austenitic steel Kh18N10T. The authors have set out the fundamental principles of elastic-plastic stress-strain analysis of the reactor core baffle and core barrel, taking into account the irradiationinduced swelling deformation and contact interaction conditions. The finite-element analysis is based on a FEM mixed scheme that ensures a continuous approximation both for displacements as well as stresses and strains, thus providing a high-accuracy determination of the stress-strain state. The calculations were carried out in the two-dimensional definition for the baffle cross-section with the maximum damaging dose and irradiation temperature in the baffle height, assuming a generalized plane-strain deformation. The calculated results are given for the reactor full-power operation and scheduled shutdown for re-fueling at the end of the charge life. According to the calculation data, disregarding the irradiation-induced swelling deformation leads to an incorrect assessment of the change in shape of the core baffle during its operation, while the use of the accepted free swelling model gives too conservative results on the shape change, even within the designed lifetime. The influence of the mean normal stress on the irradiation-induced swelling of metal makes the principal contribution to the change in shape of the core baffle. During the reactor operation beyond the designed lifetime there occurs a local contact between the core baffle and the core barrel in the zone of the largest-diameter circular opening of the longitudinal cooling channel and the port channel for coolant flow between the baffle and the barrel. The paper gives results of the analysis of the change in shape of the baffle in modeling of the contact conditions taking into consideration the temperature re-distribution due to deviation from the design coolant passage conditions in the zone where the baffle is in contact with the barrel. In the case of using the median dependence of the free swelling, no loss of the nominal gap between the core baffle and the core barrel is observed within the designed lifetime. The computational assessment using the conservative parameters of the irradiation-induced swelling leads to a distinct decrease of the gap between the core baffle and the core barrel and a local contact between them at the end of the designed lifetime. The residual gap between the spacer grids of edge fuel assemblies and the baffle faces is ensured in the case of the median and conservative dependence of the irradiation-induced swelling.

New continuous total ozone, UV, VIS and PAR measurements at Marambio, 64° S, Antarctica

Abstract. A ground-based ultraviolet (GUV) multi-filter radiometer was set up at Marambio, 64∘ S, 56∘ W, Antarctica, in 2017. The instrument continuously measures ultraviolet (UV) radiation, visible (VIS) radiation and photosynthetically active radiation (PAR). The measurements are designed for providing high-quality long-term time series that can be used to assess the impact of global climate change in the Antarctic region. The quality assurance includes regular absolute calibrations and solar comparisons performed at Marambio and at Sodankylä, Finland. The measurements continue observations at Marambio that were performed with (Norwegian Institute for Air Re-search UV Radiometer (NILU-UV) radiometers between 2000 and 2010 as part of the Antarctic NILU-UV network. These measurements are ideally suited for assessing the effects of the ongoing stratospheric ozone recovery on the ecosystem, as the data products include information on radiation at various wavelengths ranging from UV to VIS so that changes on biologically effective radiation due to ozone can be separated from those due to other factors. Data products include total ozone, photosynthetically active radiation (PAR), visible (VIS) radiation at 555 nm, UV index, UV irradiance at 5 channels, UVB and UVA dose rate and daily dose, and biologically weighted UV dose rate and daily dose, calculated with 10 different action spectra. The data from the last 5 d and the daily maximum UV index time series are plotted and updated daily on the following web page: http://fmiarc.fmi.fi/sub_sites/GUVant/ (last access: 17 April 2020). The first 2 years of UV measurements were very different in terms of the results: for October, November and December the monthly average of daily maximum UVB dose rates were clearly higher in 2018 than in 2017. The largest difference was observed in October, when the average of daily maximum UVB dose rates was 76 and 102 µW cm−2 in 2017 and 2018, respectively. Monthly averages of the 3 months were similar in 2018, while in 2017 the monthly average of October was lower than those of November and December. The VIS and PAR time series show that daily maxima in 2018–2019 exceed those in 2017–2018 during late spring and summer (mid-November–January). The studied dataset, including daily maximum irradiances at five UV channels and one VIS channel; daily maximum UVB, UVA, and PAR dose rates; noon UVB, UVA, and PAR dose rates; noon total column ozone; and UVB and UVA daily doses, is freely accessible at https://doi.org/10.5281/zenodo.3688700 (Lakkala et al., 2019).

Visible Light as an Antimicrobial Strategy for Inactivation of Pseudomonas fluorescens and Staphylococcus epidermidis Biofilms

The increase of antimicrobial resistance is challenging the scientific community to find solutions to eradicate bacteria, specifically biofilms. Light-Emitting Diodes (LED) represent an alternative way to tackle this problem in the presence of endogenous or exogenous photosensitizers. This work adds to a growing body of research on photodynamic inactivation using visible light against biofilms. Violet (400 nm), blue (420 nm), green (570 nm), yellow (584 nm) and red (698 nm) LEDs were used against Pseudomonas fluorescens and Staphylococcus epidermidis. Biofilms, grown on a polystyrene surface, were irradiated for 4 h. Different irradiance levels were investigated (2.5%, 25%, 50% and 100% of the maximum irradiance). Surviving cells were quantified and the inactivation kinetic parameters were estimated. Violet light could successfully inactivate P. fluorescens and S. epidermidis (up to 6.80 and 3.69 log10 reduction, respectively), while blue light was effective only against P. fluorescens (100% of maximum irradiance). Green, yellow and red irradiation neither increased nor reduced the biofilm cell density. This is the first research to test five different wavelengths (each with three intensities) in the visible spectrum against Gram-positive and Gram-negative biofilms. It provides a detailed study of the potential of visible light against biofilms of a different Gram-nature.