Absorber Of Radiation Research Articles

Effect of Base Angle of an Isosceles Trapezoidal Solar Air Heater Duct on Flow and Thermal Characteristics—A Numerical Investigation

Abstract This paper reports the computational results of fluid flow and thermal characteristics in an isosceles trapezoidal solar air heater (SAH). By varying the base angle of the trapezoidal duct from 90 deg to 45 deg, six different models of solar air heater ducts are obtained. The six geometries of SAH ducts have cross sections of rectangular (90 deg), triangular (45 deg), and four isosceles trapezoidal (having base angles of 50 deg, 60 deg, 70 deg, and 80 deg) shapes. The solar radiation absorber plate width and the duct heights are maintained constant for all six models of SAH, i.e., 160 mm and 80 mm, respectively. The SAH is subjected to a constant and uniform heat flux value of 1000 W/m2 and Reynolds numbers varied from 5000 to 28,000. In all six cases, the size of the air heater is the same and having dimensions of 0.16 m width and 1 m length. For this investigation, a three-dimensional computational model has been developed and simulations are carried out using commercially available ansys fluent software. The numerical results are validated with the standard correlations and literature data, and a suitable model has been identified for the turbulence closure. A detailed analysis of the Nusselt number, temperature distribution over the SAH, and friction factor across the SAH duct is done. Empirical correlations for the estimation of heat transfer and friction factor have been developed as functions of the base angle of the duct and Reynolds number. An overall performance factor (λ) is adopted to get the combined effect of friction factor and Nusselt number with an intention to arrive at the optimum base angle of the SAH duct, and optimum geometry is identified. Based on the value of λ, it is concluded that the SAH duct with the highest base angle (90 deg) in this investigation, i.e., the rectangular duct, is the optimum among all the ducts considered in the study.

Degradation process on total solar irradiance radiometers due to UV radiation

During their lifetime, total solar irradiance (TSI) radiometers are exposed to different environmental conditions and processes that may degrade the coating that is used as absorber of the incoming radiation to be measured. We were able to reproduce in the laboratory the degradation observed in space with PMO6-type radiometers in instruments like PREMOS, using high-intensity UV light and show that a novel carbon nanotube coating does not degrade under the same conditions.

A study for gamma-ray attenuation performances of barite filled polymer composites

In this study, radiation protection efficiency (RPE) for the coded as UP-Ba0, UP-Ba25, UP-Ba50, UP-Ba75 and UP-Ba100 at different sample thicknesses, total mass attenuation coefficient (μ/ρ), linear attenuation coefficients (μ), half value layers (HVL), tenth value layers (TVL), mean free paths (MFP), effective atomic numbers (Zeff) and effective electron densities (NE) were determined at various gamma energies between 59.5 and 1408.0 keV. With the help of the geometric progression (G-P) fitting method, the energy absorption build-up factor (EABF) and exposure build-up factor (EBF) values were calculated in the energy range from 0.015 MeV to 15 MeV for the produced composites. HPGe detector and eight radioactive sources (241Am, 152Eu, 137Cs, 133Ba, 60Co, 57Co, 54Mn and 22Na) were utilized in the experiment. Experimental results were compared with theoretical calculations and it has been observed that there is a good agreement between theoretical and experimental results. It was observed that RPE, μ/ρ, μ, Zeff and NE parameters increased with increasing barite amount and decreased with increasing energy, while the opposite situation was observed in HVL, TVL and MFP parameters. EABF and EBF values increase with increasing penetration depth. As a result, UP-Ba100 is a good radiation absorber according to the other studied barite filled polymer composites.

Terahertz radiation detection with a cantilever-based photoacoustic sensor.

We report the photoacoustic (PA) response in the terahertz (THz) range by employing a detection process actuated with a silicon cantilever pressure sensor and a carbon-based radiation absorber. The detection relies on the mechanical response of the cantilever, when the volume of the carrier gas inside the PA cell expands with the heat produced by the radiation absorber. The detector interferometrically monitors the movement of the cantilever sensor to generate the PA signal. We selected the absorber material with the highest THz responsivity for detailed studies at 1.4 THz (214 µm wavelength). The observed responsivities of two different radiation absorbers are nearly the same at 1.4 THz and agree within 10% with responsivity values at 0.633 µm wavelength. The results demonstrate the potential of covering with a single PA detector a broad spectral range with approximately constant responsivity, large dynamic range, and high damage threshold.

Structural, electronic, optical and mechanical properties of oxide-based perovskite ABO3 (A = Cu, Nd and B = Sn, Sc): A DFT study

The structural, electronic, optical and mechanical properties for oxide-based cubic perovskites ABO3 (A ​= ​Nd, Cu and B= Sc, Sn) were investigated employing density functional theory (DFT) within the CASTEP (Cambridge Serial Total Energy Package) code, based on ultra-soft pseudo-potential (USP) plane wave and Perdew Burke Ernzerhof (PBE) exchange-correlation functional of Generalized Gradient Approximation (GGA) and Local Density Approximation (LDA). The structural results showed that all compounds are stable. The computed elastic constants also meet the requirements of mechanical stability, hardness, ductile/brittle and bonding nature of materials. All the compounds have anisotropic nature. The electronic band structure calculations show that CuScO3 and CuSnO3 compounds have indirect band gap nature. NdScO3 compound has a direct band gap and NdSnO3 compounds show metallic behavior. All the compounds were identified as semiconductors, except NdSnO3 compounds. The band gap values were in the best agreement with the information that is already available. Partial density of states (PDOS) and total density of states (TDOS) were employed to measure the degree of localized electrons in different bands. The optical transition in the compounds was computed by fitting the dispersion relation of the imagined component. Optical properties showed that these compounds were excellent absorbers of incident radiation. Therefore, it may be assumed that these compounds could be in employment in optoelectronics to capture the ultraviolet range of solar radiations.

Effect of nano ferrosilicon and heavyweight fine aggregates on the properties and radiation shielding of ultra-high performance heavyweight concrete

Minerals such as ilmenite and magnetite better absorb gamma rays compared with silica aggregates because of their elevated densities. However, utilizing such minerals as key elements in ultra-high performance heavyweight concrete (UHPHWC) demonstrates promising outcomes, in addition to the enhanced tensile strength of the optimum radiation absorber for nuclear sites. This paper presented ilmenite and magnetite separated from black sand for use as substitutes for fine aggregates in the production of UHPHWC. In addition, nano ferrosilicon (NFS) at 1%, 2%, and 3% of the cement mass was developed using a mechanical method and mixed into the UHPHWC mixes. Their effects on the microstructure, gamma-ray attenuation coefficient, mechanical properties, and density of UHPHWC were explored. The total replacement of fine sand with ilmenite and magnetite enhanced the attenuation efficiency of the concrete mixes by 18.9% and 24.2%, respectively, after 28 days. The addition of 3% NFS to produce UHPHWC achieved the highest compressive strengths of 130.5, 167.2, and 189.8 MPa after 7, 28, and 91 days, respectively. In addition, the combination comprising 3% NFS and 100% magnetite acquired the maximum density and gamma-ray attenuation coefficient values.

Deposited layer substrate (DeLaS)-A module for radiation measurement.

Infrared Imaging Video Bolometer (IRVB) measures the radiation from plasma in two-dimensions. IRVB uses a few micrometer thick metal foil as a radiation absorber. The foil being ultra-thin has several limitations. A new radiation absorbing module is proposed here that can effectively overcome the shortcomings of the foils used in IRVB. This module is developed by depositing carbon and metal thin films on an infrared transmitting substrate using magnetron sputtering. This patented module is termed Deposited Layer on a Substrate. A prototype is developed and laboratory tests are carried out using a laser source to demonstrate its feasibility as a radiation detector. The advantages of this module over conventional foils, its development, and experimental results validating the concept are discussed in this article.

Structural, mechanical, thermodynamic, electronic, magnetic and optical properties of ZnFe2O4 ferrite: A DFT study

The density functional theory (DFT) was employed to investigate the influence of externally applied pressure ranging from 0 to -35 GPa on the structural, electronic, elastic, thermodynamic, optical and magnetic properties of ZnFe2O4 ferrite. The values of the lattice constant of the ZnFe2O4 ferrite as calculated by the computed patterns of XRD proved to be a function of applied pressure and ranged from 8.458 to 7.949 Å whereas, its direct bandgap ranged from 1.246 to 0.563 eV versus 0–35 GPa applied pressure. Thus, both the calculated parameters exhibited an inverse response against the externally applied pressure. The B/G showed that the ZnFe2O4 ferrite was ductile at all the values of applied pressure whereas, the Poisson's ratio indicated that the compound was having an ionic nature of bonding. Owing to the structural stability and the ionic interplay among O2−, Fe3+ and Zn2+ ions in the ZnFe2O4 ferrite, it becomes a suitable compound for application as anode material in high-performance lithium-ion batteries. Moreover, the computed sound velocities and the bond lengths behaved inversely versus the applied pressure and a decrease in their values was noted at higher values of pressure owing to the varying valence electrons of Fe ions. The calculation of the optical parameters showed that ZnFe2O4 ferrite was an excellent absorber of solar radiation in the visible light region and hence, it is an attractive candidate for photocatalytic applications.

Characterization of the Thermal Properties of Ir/Pt Bilayer Transition Edge Sensors

We are developing a low-\(T_c\) TES-based large-area and low-threshold detector targeting a variety of potential applications. The detector consists of a 50.8-mm-diameter Si wafer as the substrate and radiation absorber, a single Ir/Pt bilayer TES sensor in the center, and normal metal Au pads added to the TES to strengthen the TES–absorber thermal coupling. Tight TES–absorber thermal coupling improves detector sensitivity and response uniformity. Here, we report on the electron–phonon (e–ph) coupling strengths for the Ir/Pt bilayer and Au that are measured with our prototype detectors and TES devices. We found that a second weak thermal link besides the one due to e–ph coupling in Ir/Pt or Au was required to explain our data. With the effects of the second weak link accounted for, the extracted e–ph coupling constant \(\varSigma \) for Ir/Pt bilayer in the \(T_c\) range between 32 and 70 mK is \(1.9 \times 10^8\ {{\,\mathrm{\mathrm {WK^{-5}m^{-3}}}\,}}\), and \(\varSigma \)’s for Au at 40 mK and 55 mK are \(2.2 \times 10^9\ {{\,\mathrm{\mathrm {WK^{-5}m^{-3}}}\,}}\) and \(3.2 \times 10^9\ {{\,\mathrm{\mathrm {WK^{-5}m^{-3}}}\,}}\), respectively.

Constructing cross-functional intumescent flame retardants with UV resistance for polypropylene composites

Cross-functional additives were carefully designed for polypropylene (PP) composites to enhance the flame retardancy, UV resistance, and mechanical properties. In this work, first, ammonium polyphosphate (APP) was coated with polysiloxane to avoid the pyrolysis of APP under UV irradiation; second, the charring formation agent (CFA) with triazine groups was selected to enhance the absorbance of UV radiation. Hindered amine light stabilizer (TEMP) was reacted with sodium lignin sulfonate (SLS) to obtain SLS-TEMP. By using 19 wt.% (SiAPP/CFA)/2 wt.% SLS-TEMP, the limiting oxygen index of the PP composite was increased to 33.5 and the UL-94 grade was achieved to V-0. The peak heat release rate and peak smoke release rate were reduced by 76% and 74% compared with that of the control PP sample, respectively. Moreover, the aging process of the PP composite sample was delayed. The tensile and impact strength of the PP/19 wt.%(SiAPP/CFA)/2 wt.%SLS-TEMP sample was decreased by 13.4% and 27.8%, respectively after 60 h UV irradiation, which was significantly lower than that of control PP (50.9% and 68%). The change of limiting oxygen index before and after aging was minimal, and the sample still passed UL-94 V-0 grade after 100 h UV-aging test. It was proved that the SLS-TEMP has an excellent synergy effect on improving the flame retardancy and UV resistance of PP. This cross-functional additive strategy provides a good solution for obtaining high-performance PP composites.

Performance analysis of lead-free halide double perovskite-based photovoltaic devices for solar cell conception

The conception and modeling of a photovoltaic cell are done by combining the density functional theory (DFT) and solar cell capacitance simulator (SCAPS). The search for new lead-free halide semiconductor perovskite materials with an appropriate band gap, which can be used as good absorbers of solar radiation in the studied photovoltaic cell, is realized by substituting a percentage of sodium (Na) with potassium (K) and sulphur (S) in the double perovskite Cs2NaCrCl6. The study also focuses on the choice of the best materials for the electron transport layer (ETL) and the hole transport one (HTL) as well as the thickness of the perovskite semiconductor materials Cs2Na1−xXxCrCl6 (X = S and K). The results reveal that Cu2O and WS2 are suitable materials for HTL and ETL layers, respectively. The optimal thickness of the perovskite semiconductor is equal to 2μm. Under optimized conditions, the photovoltaic device power conversion efficiency (η) equals 15.01 % and 20.01 % by using Cs2Na0.5K0.5CrCl6 with Eg = 1.8eV and Cs2NaCrCl6 with Eg = 1.6eV as active layer, respectively. Therefore, the obtained photovoltaic cell model is (Cu2O/Cs2NaCrCl6/WS2/FTO), with an efficiency of η = 20.01 %.

Biological Activities of Plant Ethanolic Extracts from Asplenium trichomanes (Maidenhair spleenwort) and Lagenaria siceraria (Bottle Gourd)

Plant is commonly known as one of the main dietary sources of the human being. Many plant-derived compounds have been used as drugs, either in their original or semi-synthetic form. There are also several plant extracts or “phytomedicine” in clinical trials for the treatment of various diseases. Plant-derived compounds will still be an essential aspect of the therapeutic array of medicines available to the physician, particularly with the availability of new hyphenated primary analytical methods by determining biological activities of medicinal plants. The ethanolic extracts of two creeper plants namely Asplenium trichomanes (Maidenhair spleenwort), Lagenaria siceraria (Bottle gourd), originated from different geographical part of the world were chosen to be determine its antimicrobial, antioxidants, anti-inflammatory and UV radiation absorbance activity which is mainly characterize the anticancer activity which is nowadays become the most fatal disease. Such kind of biomedical and biotechnology approaches have been aimed to eradicate naturally such illness which is the main objective of this work. The present study shows that different ethanolic leaf extracts have an important and necessary antioxidant and anti-inflammatory properties with UV absorbing activity at UV–A region. These results show that Asplenium trichomanes and Lagenaria siceraria will be potential natural sources of antioxidant and anti-inflammatory activity. They could have greater importance as therapeutic agents in preventing or treating oxidative stress and inflammation related disorders, such as cancer and other health disorders. While the negative result of the antimicrobial activity of most of both ethanolic extract is considered as a positive result depending to main purpose of future work. Because it shows that extracts will never upset the gastric flora, in which they must be applied safely away from any harmful reaction and allergic or side effects for the living organism.

DEPENDENCE OF OPTICAL PROPERTIES OF TWO-LAYERED METAL-DIELECTRIC SPHERICAL NANOPARTICLES ON TEMPERATURE

The dependences of the efficiency factors of radiation absorption by spherical hybrid nanoparticles of the core-shell system, respectively, with gold-quartz and quartz-gold materials with core radii r0 = 40, 50, 60, 70 nm and shell thicknesses Δr1 = 10, 20, 30 nm in the wavelength range of 300–3000 nm at temperatures of particles and surrounding quartz T = 300, 1173 K are theoretically calculated and studied. Essential change of radiation absorption by a nanoparticle is established with an increase of temperatures of nanoparticles and environment. The change of optical properties of nanoparticles significantly influences the efficiency of energy absorption of solar or optical radiation by nanoparticles, heating temperature of nanoparticles and environment and further thermal processes. The results are interesting for purposes of creation of high-temperature solid nanostructured absorbers of solar radiation containing absorbing radiation of a nanoparticle and also for creation of new materials for high-temperature nanophotonics.

Optical Behavior of Human Skin Substitutes: Absorbance in the 200-400 nm UV Range.

The most recent generation of bioengineered human skin allows for the efficient treatment of patients with severe skin defects. Despite UV sunlight can seriously affect human skin, the optical behavior in the UV range of skin models is still unexplored. In the present study, absorbance and transmittance of the UGRSKIN bioartificial skin substitute generated with human skin cells combined with fibrin-agarose biomaterials were evaluated for: UV-C (200–280 nm), -B (280–315 nm), and -A (315–400 nm) spectral range after 7, 14, 21 and 28 days of ex vivo development. The epidermis of the bioartificial skin substitute was able to mature and differentiate in a time-dependent manner, expressing relevant molecules able to absorb most of the incoming UV radiation. Absorbance spectral behavior of the skin substitutes showed similar patterns to control native skin (VAF > 99.4%), with values 0.85–0.90 times lower than control values at 7 and 14- days and 1.05–1.10 times the control values at 21- and 28-days. UV absorbance increased, and UV transmission decreased with culture time, and comparable results to the control were found at 21 and 28 days. These findings support the use of samples corresponding to 21 or 28 days of development for clinical purposes due to their higher histological similarities with native skin, but also because of their absorbance of UV radiation.

Thermal Prandtl-Eyring hybridized [formula omitted]-[formula omitted] and [formula omitted]-[formula omitted] nanofluids for effective solar energy absorber and entropy optimization: A solar water pump implementation

The functional properties of a hybridized nanofluid offer high applications in nanotechnology advancement and efficient industrial output. Hence, this analysis focuses on the dynamical properties of a magnetized viscoplastic nanofluid of solar heat absorber for water pump. The hybridization of Prandtl-Eyring fluid, molybdenum disulfide and silicon dioxide nanoparticles in propylene glycol liquid is examined with Ohmic heating and viscous dissipation. A second order parabolic trough slip collector of radiative solar energy absorber is used to study the flowing fluid characteristics. A dimensionless mathematical model is obtained with convective cooling and slip boundary conditions via similarity quantities, and the model is solved by Chebyshev collocation technique. The optimization of entropy is determined using the thermodynamic second law. In tabular form, the results comparison is done, and the wall friction and heat gradient are presented. The hybridized nanofluid significantly lowers the entropy generation in the presence of Prandtl-Eyring material as compared to the single nanofluid.

Mechanical and thermal design of the target neutral beam absorber for the High-Luminosity LHC upgrade

The High-Luminosity target neutral beam absorber (TAXN) is the radiation absorber of the neutral particle debris generated at the beam collisions carried out in the ATLAS and CMS detectors at the Large Hadron Collider (LHC). The new absorber will protect the superconducting magnets from this radiation to prevent their quenching at a design luminosity of $7.5\ifmmode\times\else\texttimes\fi{}{10}^{34}\text{ }\text{ }{\mathrm{cm}}^{\ensuremath{-}2}\text{ }{\mathrm{s}}^{\ensuremath{-}1}$. This article describes the mechanical design of the TAXN assembly and the recombination chamber together with the thermal computations performed for the water-cooling and bakeout system prepared for the engineering design review held in January, 2021. It takes into account the internal integration of the zero degree calorimeter and beam rate of neutrals luminosity detector as well as their physics case overview. In addition, it provides the beam aperture breakdown and the heat deposition expected in the absorber.

Modeling a novel terahertz sensing scheme based on a black phosphorus-liquid crystal-DBR structure

In this work, we propose a new scheme of a photonic device containing a layer of black phosphorus, an electrically controlled nematic liquid crystal (LC) and a distributed Bragg reflector (DBR). We have studied the influence of the electron carrier density in the black phosphorus layer, as well as the thickness of the defect layer, and also the reorientation of the LC director on the reflection spectrum of the device in the THz spectral range. It is shown how a change in these parameters affects the reflection spectra of the device. Such device can be used, for example, as tunable phase shifter, modulator and absorber of electromagnetic radiation.

First-principles insights into the mechanical, optoelectronic, thermophysical, and lattice dynamical properties of binary topological semimetal BaGa2

In the present study we have investigated the structural properties, electronic band dispersion, elastic constants, acoustic behavior, phonon spectrum, optical properties, and a number of thermophysical parameters of binary topological semimetal BaGa2 in details via first-principles calculations using the density functional theory (DFT) based formalisms. The electronic band structure and density of states calculations with spin–orbit coupling reveal semimetallic nature with clear topological signatures. The minimum thermal conductivities and anisotropies of the compound are calculated. The elastic constants and phonon dispersion calculations show that the compound under study is both mechanically and dynamically stable. Comprehensive study of elastic parameters shows that BaGa2 possesses fairly isotropic mechanical properties, reasonably good machinability, low Debye temperature and melting point. The chemical bonding in BaGa2 is interpreted via the electronic energy density of states, electron density distribution, elastic properties and Mulliken bond population analysis. The compound possesses both ionic and covalent bondings. The reflectivity spectra show strong anisotropy with respect to polarization of the incident electric field in the visible to mid-ultraviolet regions. High reflectivity over wide spectral range makes BaGa2 suitable as a reflecting material. BaGa2 is also an efficient absorber of ultraviolet radiation. Furthermore, the refractive index is quite high in the infrared to visible range. All the energy dependent optical parameters show metallic features and are in complete accord with the underlying bulk electronic density of states calculations. Most of the results presented in this study are novel and should serve as useful reference for future study.

Possible applications of Mo2C in the orthorhombic and hexagonal phases explored via ab-initio investigations of elastic, bonding, optoelectronic and thermophysical properties

Binary carbides demonstrate an attractive set of physical properties that are suitable for numerous and diverse applications. In the present study, we have explored the structural properties, electronic structures, elastic constants, acoustic behaviors, phonon dispersions, optical properties, and various thermophysical properties of binary orthorhombic and hexagonal Mo2C (O-MC and H-MC, respectively) compounds in detail via first-principles calculations using the density functional theory (DFT). The calculated ground state lattice parameters in both the symmetries are in excellent agreement with available experimental results. The calculated electronic band structure, density of states, and optical properties of Mo2C in both structures reveal metallic features. The orthorhombic crystal shows a higher level of mechanical and thermal anisotropy compared to that in the hexagonal phase. The elastic constants and phonon dispersion calculations show that, in both structures, Mo2C is mechanically and dynamically stable. A comprehensive mechanical and thermophysical study shows that both phases possess high structural stability, reasonably good machinability, ductile nature, high hardness, low compressibility, high Debye temperature and high melting temperature. Moreover, the electronic energy density of states, electron density distribution, elastic properties, and Mulliken bond population analyses indicate that the structures under consideration consist of mixed bonding characteristics with ionic and covalent contributions. Investigation of the optical properties reveals that the reflectivity spectra are anisotropic with respect to the polarization directions of the electric field in the visible to mid‑ultraviolet regions. High reflectivity over a wide spectral range makes the compound suitable as reflecting coating. Both the structures are efficient absorbers of ultraviolet radiation. The refractive indices are quite high in the infrared to the visible range. Both structures show directional optical anisotropy. Though, H-MC exhibits stronger optical anisotropy than the O-MC.

Michler's Ketone: β-Cyclodextrin Host-Guest Inclusion Complex for Enhancing the Ultraviolet Protection Factor of Poplin Cotton Fabric.

Michler's ketone (4,4' bis(N,N-dimethylamino)benzophenone) mk is a potential ultraviolet radiation (UVR) absorber in various materials. In this study, we have tested the UVR filtering ability of mk on cotton fabric. The beta-cyclodextrin (β-CD) inclusion complex of mk enhances ultraviolet protection factor (UPF) drastically. The impact of β-CD on the UVR filtering of mk are demonstrated by investigating the guest (mk:absorbers)-host (β-CD:enhancer) inclusion complex. Spectral and molecular docking analysis of mk:β-CD complex infers the vertical insertion of the guest molecule by positioning -C=O group of mk at the center of the host molecule with the exclusion of the terminal atoms of guest molecule outside the β-CD cavity. Thus, the host; β-CD renders an inflexible fit to the guest:mk. The inflexible fit of mk into the β-CD cavity enhances the UVR dissipation when it is incorporated on the poplin cotton fabric. With UPF = 46 mk:β-CD complex is proposed as a potential UVR absorber suitable for manufacturing sun protective textiles. The holding of mk by β-CD enhances the UVR dissipation and hence facilitates the native red-shifted emission and non-radiative relaxation by the formation of twisted intramolecular charge transfer in mk.