Direct Sun Irradiance Research Articles

Photodegradation of Rituximab and Critical Evaluation of Its Sensibility to Electromagnetic Radiation.

Rituximab is a monoclonal antibody used in the treatment of lymphoma non-Hodgkin. This mAb is photosensitive as it is administrated to the patient by infusion/perfusion; therefore, photostability is a decisive factor in the efficacy of this biologic. To better understand the photodegradation mechanisms of Rituximab, this biologic was exposed to different irradiance conditions. We show in this study that this mAb photodegrade proportionally to irradiance intensities. The main modifications of Rituximab by irradiance correlate to the increase in aggregates, decrease in its Tm, acidic charge variants, oxidation of the Trp (36) in the heavy chain, and decrease in complement-dependent cytotoxicity (CDC) potency. To understand the relationship between real-life photo-exposition conditions and ICH standardized light tests, a full characterization was set up. Worst photo-stress cases were evaluated, 1 and 2 h under direct sunlight through a window, mimicking the ID65 electromagnetic radiation profile. Our results show that only exposition to direct sun irradiance during 2 h, (≈ 150 kluxes•h), increases critically soluble and insoluble aggregates, diminishing Tm, increasingacidic charge variants, and thephotooxidation of the Trp (36) in the heavy chain measured by peptide mapping-RP-UPLC-MS. A decrease in CDC below 80% resulted under this condition, which correlates with physicochemical analyses. While inside light-room exposition (similar to ICH test) and ICH conditions do not have any contribution to the degradation of Rituximab measured by these physicochemical and biological analytical methods. These results indicate that exposition of Rituximab to below ≈ 75 kluxes•h of sun light cannot photodegrade critically this biologic inside of its primary container.

Scalable, fire-retardant, and spectrally robust melamine-formaldehyde photonic bulk for efficient daytime radiative cooling

Traditional building materials such as wood and concrete cannot effectively regulate the heat flux of buildings. Compressor-based cooling systems are used to provide comfortable interior environments for humans, contributing significantly to global energy consumption. It has recently been demonstrated that sub-ambient passive daytime radiative cooling has been obtained by efficiently radiating thermal energy to the cold outer space through the atmospheric transparent window while reflecting most of the solar irradiance. Here, we demonstrate a high-performance daytime radiative cooling material processed by hydraulic pressing melamine-formaldehyde (MF) particles and thermally annealing them into a cross-linked photonic cooling bulk as an efficient solar reflector and infrared thermal emitter. It reaches a sub-ambient stagnation temperature of 3.6 ∘C under direct sun irradiance (750 W m−2), which is 12 ∘C and 5 ∘C below the concrete and the wood as control group temperatures, respectively. The two-step fabrication process is straightforward and can be easily scaled up for industrial manufacturing. The as-prepared MF cooling material shows highly desirable fire-retardant properties and is self-extinguishing, make it excellent material for building safety. The material is durable, and spectrally robust in harsh environments, such as long exposure to the acidic and alkaline solutions.

Optomechanical Design and Application of Solar-Skylight Spectroradiometer.

Using a solar radiometer is an effective approach for improving the remote sensing of solar irradiance distribution and atmospheric composition. Long-term development of a solar scanning radiometer enables frequent and reliable measurement of atmospheric parameters such as the water vapor column and aerosol optical properties. However, the discrete wavelength radiometer has encountered a bottleneck with respect to its insufficient spectral resolution and limited observation waveband, and it has been unable to satisfy the needs of refined and intelligent on-site experiments. This study proposes a solar-skylight spectroradiometer for obtaining visible and near-IR fine spectrum with two types of measurement: direct-sun irradiance and diffuse-sky radiance. The instrument adopts distributed control architecture composed of the ARM-Linux embedded platform and sensor networks. The detailed design of the measuring light-path, two-axis turntable, and master control system will be addressed in this study. To determine all coefficients needed to convert instrument outputs to physical quantities, integrating sphere and Langley extrapolation methods are introduced for diffuse-sky and direct-sun calibration, respectively. Finally, the agreement of experimental results between spectroradiometers and measuring benchmarks (DTF sun-photometer, microwave radiometer, and Combined Atmospheric Radiative Transfer simulation) verifies the feasibility of the spectroradiometer system, and the radiation information of feature wavelengths can be used to retrieve the characteristics of atmospheric optics.

Contribution to column-integrated aerosol typing based on Sun-photometry using different criteria

This study analyses the aerosol optical and microphysical properties obtained by the Aerosol Robotic Network (AERONET) in seven different sites operating in the Iberian Peninsula during three coincident years (2010−2012) with the objective of studying different aerosol typing approaches. This area is of interest due to its location between the Sahara desert (the largest source of natural aerosols in the world) and mainland Europe (a relevant source of anthropogenic aerosols). In particular, we study the aerosol optical depth (AOD), Angström parameter (α440–870) and fine mode fraction (FMF), which are estimated from direct sun irradiance measurements. Additionally, the single scattering albedo (ωo) and aerosol particle size distribution (PSD), which are computed using additional sky radiances measurements under cloudless skies, are used in our analyses. The analyses show aerosol seasonal patterns in the AOD with maximum values in summer/spring and minimum values in winter/autumn for all the analysed stations. For α440–870, there are differences from site to site, with maximum values in winter and minimum values in summer for the southern locations, while there is not a remarkable pattern for the eastern locations close to the Mediterranean coast. The frequent and intense Saharan dust outbreaks over the southern Iberian Peninsula and the intense anthropogenic activity in the eastern urban locations are behind these seasonal patterns in the AOD and α440–870. In this work, two of the most employed classification schemes of aerosol type in the literature are used: one is based on the AOD and α440–870, the other one is based on ωo at 440 nm and the FMF and a new classification scheme based on ωo at 440 nm and FMF is proposed. The results revealed that the new classification method is more appropriate for distinguishing the aerosol types that affect the Iberian Peninsula. The relationship derived here between Δωo = ωo (440)- ωo (1020) and the FMF is demonstrated to be useful for aerosol type classification when no measurements of the sky radiances, and consequently of ωo(440), are available. Alternatively, the relationship between the ratio Δωo/ωo(440) and the FMF can be used because (Δωo/ωo) provides information about both the spectral ωo and the absolute values.

The Solar Ultraviolet Environment at the Ocean.

Atmospheric and oceanic radiative transfer models were used to compute spectral radiances between 285 and 400 nm onto horizontal and vertical plane surfaces over water. The calculations kept track of the contributions by the sun's direct beam, by diffuse-sky radiance, by radiance reflected from the sea surface and by water-leaving radiance. Clear, hazy and cloudy sky conditions were simulated for a range of solar zenith angles, wind speeds and atmospheric ozone concentrations. The radiances were used to estimate erythemal exposures due to the sun and sky, as well as from radiation reflected by the sea surface and backscattered from the water column. Diffuse-sky irradiance is usually greater than direct-sun irradiance at wavelengths below 330 nm, and reflected and water-leaving irradiance accounts for <20% of the UV exposure on a vertical surface. Total exposure depends strongly on solar zenith angle and azimuth angle relative to the sun. Sea surface roughness affects the UV exposures by only a few percent. For very clear waters and the sun high in the sky, the UV index within the water can be >10 at depths down to two meters and >6 down to 5 m.

Water vapour retrieval using the Precision Solar Spectroradiometer

Abstract. The Precision Solar Spectroradiometer (PSR) is a new spectroradiometer developed at Physikalisch-Meteorologisches Observatorium Davos – World Radiation Center (PMOD–WRC), Davos, measuring direct solar irradiance at the surface, in the 300–1020 nm spectral range and at high temporal resolution. The purpose of this work is to investigate the instrument's potential to retrieve integrated water vapour (IWV) using its spectral measurements. Two different approaches were developed in order to retrieve IWV: the first one uses single-channel and wavelength measurements, following a theoretical water vapour high absorption wavelength, and the second one uses direct sun irradiance integrated at a certain spectral region. IWV results have been validated using a 2-year data set, consisting of an AERONET sun-photometer Cimel CE318, a Global Positioning System (GPS), a microwave radiometer profiler (MWP) and radiosonde retrievals recorded at Meteorological Observatorium Lindenberg, Germany. For the monochromatic approach, better agreement with retrievals from other methods and instruments was achieved using the 946 nm channel, while for the spectral approach the 934–948 nm window was used. Compared to other instruments' retrievals, the monochromatic approach leads to mean relative differences up to 3.3 % with the coefficient of determination (R2) being in the region of 0.87–0.95, while for the spectral approach mean relative differences up to 0.7 % were recorded with R2 in the region of 0.96–0.98. Uncertainties related to IWV retrieval methods were investigated and found to be less than 0.28 cm for both methods. Absolute IWV deviations of differences between PSR and other instruments were determined the range of 0.08–0.30 cm and only in extreme cases would reach up to 15 %.

Retrieving vertical ozone profiles from measurements of global spectral irradiance

Abstract. A new method is presented to determine vertical ozone profiles from measurements of spectral global (direct Sun plus upper hemisphere) irradiance in the ultraviolet. The method is similar to the widely used Umkehr technique, which inverts measurements of zenith sky radiance. The procedure was applied to measurements of a high-resolution spectroradiometer installed near the centre of the Greenland ice sheet. Retrieved profiles were validated with balloon-sonde observations and ozone profiles from the space-borne Microwave Limb Sounder (MLS). Depending on altitude, the bias between retrieval results presented in this paper and MLS observations ranges between −5 and +3 %. The magnitude of this bias is comparable, if not smaller, to values reported in the literature for the standard Dobson Umkehr method. Total ozone columns (TOCs) calculated from the retrieved profiles agree to within 0.7±2.0 % (±1σ) with TOCs measured by the Ozone Monitoring Instrument on board the Aura satellite. The new method is called the Global-Umkehr method.

Photoactive nanocomplex formed from chlorophyll assembly on TMA-coated iron oxide nanoparticles

In this study, hierarchical self-assembly of photocatalytic nanodisks through non-covalent interactions between spinach-extracted chlorophyll molecules and trimethylammonium hydroxide-coated magnetic iron oxide nanoparticles was discussed. Combination of chlorophyll molecules with iron oxide nanoparticles generated an alteration in light absorption at both visible and near-IR region with accompanying enhancement in fluorescence emission. Further, photocatalytic role of resulting molecular assembly was studied by means of the photoinduced degradation of methylene blue dye under UV light and direct sun irradiation at neutral pH. In order to enhance the long-term stability of the hybrid nanocatalyst, commercially available cellulose membrane was used as a support and magnetic recovery and reusability was achieved where the nanocatalyst retained more than 90 % of its efficiency even after four cycles. This simple strategy could initiate the development of new materials for wastewater treatment including membrane-based technologies. On the other hand, their sunlight-induced photocatalytic activity could easily be conducted to dye-synthesized solar cells or their enhanced photoluminescence can provide a strong basis for future bioimaging tools.

Improvements for ground-based remote sensing of atmospheric aerosol properties by additional polarimetric measurements

We discuss the improvements in the aerosol properties characterization resulting from the additional multi-wavelength polarization measurements measured by a new CIMEL polarized sun/sky-photometer, CE318-DP. In order to process direct-sun, sky and polarization measurements in a wide spectral range (340–1640 nm), we developed new calibration methods and strategies, e.g. using the Langley plot method to calibrate both direct-sun irradiance and sky radiance, as well as combining laboratory facilities with a vicarious method to calibrate the polarized sky measurements. For studying the impact of new polarimetric measurements on the retrievals of aerosol properties, we have processed an extensive record of field measurements using an updated Dubovik and King retrieval algorithm [Dubovik O, Sinyuk A, Lapyonok T, Holben BN, Mishchenko MI, et al. Application of spheroid models to account for aerosol particle nonsphericity in remote sensing of desert dust. J Geophys Res 2006;111:D11208.]. A preliminary analysis shows that adding polarization in the inversion can reduce possible errors (notably for about 30% of our field cases) in the fine mode size distribution, real part of refractive index and particle shape parameter retrievals, especially for small particles.

Transferring the calibration of direct solar irradiance to diffuse-sky radiance measurements for CIMEL Sun-sky radiometers

Two types of sunphotometric measurement are considered in this study: direct-Sun irradiance and diffuse-sky radiance. Based on CIMEL CE318 Sun-sky radiometer characteristics, we introduce a gain-corrected solid angle that allows interconverting calibration coefficients of these two types of measurement, thus realizing a "vicarious" radiance calibration. The accuracy of the gain-corrected solid angle depends on the number of available historical calibration records. The method is easy to use, provided that at least one laboratory calibration has been made previously. Examples coming from three distinct CE318 versions belonging to the AERONET/PHOTONS network are presented to provide details on the vicarious calibration method and protocols. From the error propagation analysis and the comparison with laboratory results, the uncertainty of the vicarious radiance calibration is shown to be comparable with the laboratory one, e.g., 3%-5%.

Dual-aureole and sun spectrometer system for airborne measurements of aerosol optical properties

We have designed an airborne spectrometer system for the simultaneous measurement of the direct sun irradiance and the aureole radiance in two different solid angles. The high-resolution spectral radiation measurements are used to derive vertical profiles of aerosol optical properties. Combined measurements in two solid angles provide better information about the aerosol type without additional and elaborate measuring geometries. It is even possible to discriminate between absorbing and nonabsorbing aerosol types. Furthermore, they allow to apply additional calibration methods and simplify the detection of contaminated data (e.g., by thin cirrus clouds). For the characterization of the detected aerosol type a new index is introduced that is the slope of the aerosol phase function in the forward scattering region. The instrumentation is a flexible modular setup, which has already been successfully applied in airborne and ground-based field campaigns. We describe the setup as well as the calibration of the instrument. In addition, example vertical profiles of aerosol optical properties--including the aureole measurements--are shown and discussed.

Retrieval of aerosol optical and physical properties from ground-based spectral, multi-angular, and polarized sun-photometer measurements

An inversion algorithm to retrieve a complete set of aerosol optical and physical properties has been developed. The algorithm is based on sun-photometer measurements with emphasis on polarimetric observations. At present, these polarized sun-photometer observations are mainly provided by PHOTONS network included in AERONET worldwide network. With ground-based measurement of direct sun irradiance, as well as total and polarized sky radiance, most of key characteristics of atmospheric aerosols are retrieved, including spectral single-scattering albedo from UV to NIR wavelength, elements of scattering matrix F 11 and − F 12 (i.e. phase function and polarized phase function), complex refractive index, and size distribution. These parameters are fundamentally valuable in atmospheric physical and chemical studies. The theoretical accuracy is assessed based on three distinct bimodal log-normal aerosol models. The sensitivity studies to measurement uncertainties and to observing geometrical conditions are implemented to estimate the retrieval accuracy. Examples of typical retrievals when applying to real measurements are illustrated and compared with AERONET operational inversions. The particle shape-independent advantage of the retrieved single-scattering albedo, phase function, and polarized phase function is validated by considering a non-spherical aerosol model, which consisted of spheroid particles.

Sun and aureole spectrometer for airborne measurements to derive aerosol optical properties.

We have designed an airborne spectrometer system for the simultaneous measurement of the direct Sun irradiance and aureole radiance. The instrument is based on diffraction grating spectrometers with linear image sensors. It is robust, lightweight, compact, and reliable, characteristics that are important for airborne applications. The multispectral radiation measurements are used to derive optical properties of tropospheric aerosols. We extract the altitude dependence of the aerosol volume scattering function and of the aerosol optical depth by using flight patterns with descents and ascents ranging from the surface level to the top of the boundary layer. The extinction coefficient and the product of single scattering albedo and phase function of separate layers can be derived from the airborne measurements.

Autonomous Above-Water Radiance Measurements from an Offshore Platform: A Field Assessment Experiment

Abstract An autonomous system for making above-water radiance measurements has been produced by adding a new measurement scenario to a CIMEL CE-318 sun photometer. The new system, called the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) Photometer Revision for Incident Surface Measurement (SeaPRISM), combines the normal CE-318 capability for measuring direct sun irradiance and sky radiance, with a new capability for measuring above-water radiance for the retrieval of water-leaving radiance. The system has been extensively tested during several measurement periods over a 1-yr time frame from August 1999 to July 2000 under various sun elevations along with different atmospheric, seawater, and sea-state conditions. The field assessment of the new instrument was conducted at an oceanographic tower located in the northern Adriatic Sea within the framework of measurement campaigns aimed at supporting ocean color calibration and validation activities. Sample data at 440, 500, 670, 870, and 1020 nm were collect...

Rooting and vegetative propagation in Laguncularia racemosa

Reproduction and dispersal in mangrove species occurs mainly through propagules. Vegetative propagation is considered to be insignificant by many researchers, however, for restoration projects, it could be an important advantage. Therefore, we carried out experiments with shoot cuttings of Laguncularia racemosa and Rhizophora mangle under controlled conditions as well as in the field to prove the feasibility of vegetative propagation in these mangrove species. None of 110 planted R. mangle cuttings survived the experiments, but the results with L. racemosa were promising. We observed that the single most important factor for survival of L. racemosa cuttings was rooting of the shoots prior to cutting from the parent trees. This is a common feature in the study area, the Ciénaga Grande de Santa Marta, Colombia. Seasonal floodings of lower branches induce secondary root growth and can even lead to natural vegetative propagation. Other factors that have favorable effects on the survival of the cuttings are a large shoot diameter, manual defoliation to reduce transpiration, and direct sun irradiation. Additionally, burying a small part of the roots in a way that allows some roots to freely float in the surface water, improves the survival rate to 95%. However, the watering with rooting agents shows slightly negative effects. The surviving shoots grow rapidly and fruit set can be observed within six months after planting in the field. In restoration attempts with L. racemosa it is, therefore, possible to bypass the very sensitive seedling phase by planting shoot cuttings. The value of this method is linked to quicker establishment and reproduction of the cuttings as well as the possibility to plant them in flooded areas, where establishment of propagules and survival of seedlings of L. racemosa is very difficult to achieve.

THE URINARY MELANOGEN CYSTEINYLDOPA IN MELANOMA AND IN SUNTANNING: AUSTRALIAN EXPERIENCE

Determination of urine cysteinyldopa excretion is the most sensitive chemical test for the detection of melanoma metastases and has been successfully applied during the Scandinavian winter, when sun irradiation is low. The value of this determination, under Australian conditions of greater sun irradiation, has been assessed by comparing the cysteinyldopa excretion of patients with that of normal subjects exposed to sunlight. Cysteinyldopa is an intermediate in the biosynthesis of the red-brown phaeomelanin. Of 20 patients without known secondary melanoma, the cysteinyldopa concentration of "spot" urines ranged from 0 to 190 (mean 48) microgram/ml; of six known to have local metastases, 0 to 80 (mean 19) microgram/ml; and of four known to have extensive metastases 80 to 1350 (mean 330) microgram/ml. The effect of sun irradiation alone was assessed in nine healthy subjects followed one to 11 weeks before and after recorded periods of sun exposure. The cysteinyldopa concentrations of 24-hour urines ranged from 40 to 3100 microgram/ml. Increases occurred three to 10 days following sun exposure and were greatest following multiple small exposures in an individual with "Celtic" complexion. It is concluded that measurement of cysteinyldopa concentration would be of value in the follow-up of melanoma patients in Australia only if patients could be persuaded to live under conditions free of all direct sun-irradiation.