scholarly journals Lead evaporation by VUV radiation of various spectral ranges

2021 ◽  
Vol 2064 (1) ◽  
pp. 012078
Author(s):  
A V Pavlov ◽  
T S Shchepanuk ◽  
E O Chebykin ◽  
Yu Yu Protasov ◽  
V D Telekh
Keyword(s):  
Ionization Potential ◽  
Plasma Layer ◽  
Spectral Composition ◽  
Radiation Energy ◽  
Inert Gases ◽  
Lead Target ◽  
Buffer Gas ◽  
Gas Filtration ◽  
Spectral Ranges ◽  
The Impact

Abstract The results of an experimental study of the plasma formed by the evaporation of the lead target in the field of powerful broadband VUV radiation are presented. A pulse light-erosion magnetoplasma compressor (MPC’s) discharge is used as a model source of VUV radiation. “Gas filtration” of radiation is used to control the spectral composition – the discharge takes place in pure inert gases: in argon at 200 torr and neon at 400 torr. This allows us to manage the spectral distribution of radiation energy and to limit the energy of quants which irradiate the lead target with the first ionization potential of buffer gas. Shadow photography, toeplergrathy, double exposure laser holographic interferometry are used for diagnostics. Experimentally established different distribution of parameters in the lead plasma depending on the spectral composition of the impact radiation (the composition of buffer gas). It is shown that when the energy of quants increases (above the lead second ionization potential), a more even heating of the plasma layer is realized.

scholarly journals Emission of a low-power laser-induced vacuum discharge plasma in the EUV and SXR spectral ranges

2018 ◽  
Vol 167 ◽  
pp. 03010
Author(s):  
Alexander Rupasov ◽  
Igor Romanov ◽  
Andrey Kologrivov ◽  
Viktor Paperny
Keyword(s):  
Discharge Plasma ◽  
Spectral Characteristics ◽  
Spectral Composition ◽  
Radiation Energy ◽  
Vacuum Discharge ◽  
Power Laser ◽  
X Ray ◽  
Long Wavelength ◽  
Spectral Ranges ◽  
Storage Energy

X-ray spectral characteristics of a vacuum discharge plasma with the storage energy lower than 30 J initiated on an Al or a Fe cathode by a 1012 W/cm2 neodymium laser were studied in the 30 – 300 Å wavelength range. It is shown that both the spectral composition and intensity of radiation of a micropinch plasma produced in the cathode jet of the discharge are determined by parameters of the discharge and laser pulse. These parameters were optimized to achieve a regime in which a considerable part of radiation energy was concentrated in the long-wavelength band of the quasi-continuum (230 - 270 Å and 160 - 200 Å for Al and Fe, respectively), which makes this discharge a source of narrowband X-ray radiation.

scholarly journals Ocular growth and metabolomics are dependent upon the spectral content of ambient white light

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Raymond P. Najjar ◽  
Juan Manuel Chao De La Barca ◽  
Veluchamy A. Barathi ◽  
Candice Ee Hua Ho ◽  
Jing Zhan Lock ◽  
...  
Keyword(s):  
Critical Role ◽  
Spectral Composition ◽  
Light Therapy ◽  
World Population ◽  
Spectral Content ◽  
Ocular Growth ◽  
Nitric Oxide Metabolism ◽  
Therapy Strategies ◽  
Indoor Lighting ◽  
The Impact

AbstractMyopia results from an excessive axial growth of the eye, causing abnormal projection of remote images in front of the retina. Without adequate interventions, myopia is forecasted to affect 50% of the world population by 2050. Exposure to outdoor light plays a critical role in preventing myopia in children, possibly through the brightness and blue-shifted spectral composition of sunlight, which lacks in artificial indoor lighting. Here, we evaluated the impact of moderate levels of ambient standard white (SW: 233.1 lux, 3900 K) and blue-enriched white (BEW: 223.8 lux, 9700 K) lights on ocular growth and metabolomics in a chicken-model of form-deprivation myopia. Compared to SW light, BEW light decreased aberrant ocular axial elongation and accelerated recovery from form-deprivation. Furthermore, the metabolomic profiles in the vitreous and retinas of recovering form-deprived eyes were distinct from control eyes and were dependent on the spectral content of ambient light. For instance, exposure to BEW light was associated with deep lipid remodeling and metabolic changes related to energy production, cell proliferation, collagen turnover and nitric oxide metabolism. This study provides new insight on light-dependent modulations in ocular growth and metabolomics. If replicable in humans, our findings open new potential avenues for spectrally-tailored light-therapy strategies for myopia.

GaN Radiation Detection Research Based on Monte Carlo Method

2014 ◽  
Vol 668-669 ◽  
pp. 1011-1014
Author(s):  
Yang Liu ◽  
Guo Zheng Zhu ◽  
Zhen Ni Xing
Keyword(s):  
Monte Carlo ◽  
Energy Deposition ◽  
Detection Efficiency ◽  
Hadron Collider ◽  
Radiation Detection ◽  
Radiation Energy ◽  
Radiation Detectors ◽  
Detection Mechanism ◽  
Radiation Beam ◽  
The Impact

Gallium nitride (GaN) is the third generation of semiconductor material; it has a large band gap, high thermal conductivity, low dielectric constant, high drift speed, etc. Radiation detectors based on GaN material have small volume, high radiation resistance, and fast response, can be used to replace the existing Large Hadron Collider vertex detector and track detector. Energy deposition characteristic of GaN detectors to radiation beam is an important factor for detection efficiency, and there are many factors that affect the energy deposition characteristics of the detector, like the detection mechanism, the impact of material properties, the type of incident ray, radiation energy, and many other factors. This paper studies the physical properties of GaN detector by calculation based on Monte Carlo simulation. Energy deposition characteristics are discussed respectively for incident γ-ray with different energy, in the front-end and back-end add PTFE material. The results of our study present the theoretical properties of GaN radiation detectors.

scholarly journals Experimental Etching of Diamonds: Extrapolation to Impact Diamonds from the Popigai Crater (Russia)

Minerals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1229
Author(s):  
Valeri Sonin ◽  
Egor Zhimulev ◽  
Aleksei Chepurov ◽  
Ivan Gryaznov ◽  
Anatoly Chepurov ◽  
...  
Keyword(s):  
Large Range ◽  
Ambient Pressure ◽  
Inert Gases ◽  
Oxidation States ◽  
Silicate Melts ◽  
Etch Pits ◽  
Diamond Crystals ◽  
Surface Graphitization ◽  
O2 Diffusion ◽  
The Impact

Diamond etching in high-temperature ambient-pressure experiments has been performed aimed to assess possible postimpact effects on diamonds in impact craters, for the case of the Popigai crater in Yakutia (Russia). The experiments with different etchants, including various combinations of silicate melts, air, and inert gases, demonstrated the diversity of microstructures on {111} diamond faces: negative or positive trigons, as well as hexagonal, round, or irregularly shaped etch pits and striation. The surface features obtained after etching experiments with kimberlitic diamonds are similar to those observed on natural impact diamonds with some difference due to the origin of the latter as a result of a martensitic transformation of graphite in target rocks. Extrapolated to natural impact diamonds, the experimental results lead to several inferences: (1) Diamond crystals experienced natural oxidation and surface graphitization during the pressure decrease after the impact event, while the molten target rocks remained at high temperatures. (2) Natural etching of diamonds in silicate melts is possible in a large range of oxidation states controlled by O2 diffusion. (3) Impact diamonds near the surface of molten target rocks oxidized at the highest rates, whereas those within the melt were shielded from the oxidizing agents and remained unchanged.

The Use of Lasers at Various Stages of the Manufacturing Process of Solar Cells Based on Crystalline Silicon

2020 ◽  
Vol 308 ◽  
pp. 138-156
Author(s):  
Małgorzata Musztyfaga-Staszuk ◽  
Piotr Panek
Keyword(s):  
Solar Cells ◽  
Laser Radiation ◽  
Crystalline Silicon ◽  
Point Contact ◽  
Radiation Energy ◽  
Photovoltaic Cell ◽  
Materials Engineering ◽  
University Of Technology ◽  
Academy Of Sciences ◽  
The Impact

The purpose of this chapter of the book is to present knowledge on the use of laser technology in silicon photovoltaic cell manufacturing processes. Particular consideration was given to the technique of using a disk laser to cut the edges of silicon wafers together with the recognition of the flow of laser micromachining on the quality of cut edges to obtain their minimal deformation. The second topic described is the method of producing point contacts employing laser radiation between a layer of vaporised aluminium and crystalline silicon using the Nd:YAG laser. The results illustrating the impact of the structure and parameters of point contact for a given laser radiation energy on basic electrical parameters for complete, prototype solar cells are included. The chapter in the book provides an overview of the literature on the above topics and presents selected results of experimental works carried out by the authors. The motive for its publication is the need to present selected results of own research carried out in the Welding Department cooperating for many years with the Institute of Engineering and Biomedical Materials (IMIiB) of the Silesian University of Technology and the Institute of Metallurgy and Materials Engineering (IMIM) of the Polish Academy of Sciences in Cracow.

scholarly journals Can downwelling far-infrared radiances over Antarctica be estimated from mid-infrared information?

2019 ◽  
Vol 19 (11) ◽  
pp. 7927-7937
Author(s):  
Christophe Bellisario ◽  
Helen E. Brindley ◽  
Simon F. B. Tett ◽  
Rolando Rizzi ◽  
Gianluca Di Natale ◽  
...  
Keyword(s):  
Climate Models ◽  
Far Infrared ◽  
Mid Infrared ◽  
Spectral Bands ◽  
Noise Characteristics ◽  
Infrared Spectral ◽  
Infrared Radiances ◽  
Spectrally Resolved ◽  
Spectral Ranges ◽  
The Impact

Abstract. Far-infrared (FIR: 100cm-1<wavenumber, ν<667 cm−1) radiation emitted by the Earth and its atmosphere plays a key role in the Earth's energy budget. However, because of a lack of spectrally resolved measurements, radiation schemes in climate models suffer from a lack of constraint across this spectral range. Exploiting a method developed to estimate upwelling far-infrared radiation from mid-infrared (MIR: 667cm-1<ν<1400 cm−1) observations, we explore the possibility of inferring zenith FIR downwelling radiances in zenith-looking observation geometry, focusing on clear-sky conditions in Antarctica. The methodology selects a MIR predictor wavenumber for each FIR wavenumber based on the maximum correlation seen between the different spectral ranges. Observations from the REFIR-PAD instrument (Radiation Explorer in the Far Infrared – Prototype for Application and Development) and high-resolution radiance simulations generated from co-located radio soundings are used to develop and assess the method. We highlight the impact of noise on the correlation between MIR and FIR radiances by comparing the observational and theoretical cases. Using the observed values in isolation, between 150 and 360 cm−1, differences between the “true” and “extended” radiances are less than 5 %. However, in spectral bands of low signal, between 360 and 667 cm−1, the impact of instrument noise is strong and increases the differences seen. When the extension of the observed spectra is performed using regression coefficients based on noise-free radiative transfer simulations the results show strong biases, exceeding 100 % where the signal is low. These biases are reduced to just a few percent if the noise in the observations is accounted for in the simulation procedure. Our results imply that while it is feasible to use this type of approach to extend mid-infrared spectral measurements to the far-infrared, the quality of the extension will be strongly dependent on the noise characteristics of the observations. A good knowledge of the atmospheric state associated with the measurements is also required in order to build a representative regression model.

scholarly journals Liquid Platelet-Rich Fibrin and Heat-Coagulated Albumin Gel: Bioassays for TGF-β Activity

Materials ◽  
2020 ◽  
Vol 13 (16) ◽  
pp. 3466
Author(s):  
Zahra Kargarpour ◽  
Jila Nasirzade ◽  
Layla Panahipour ◽  
Richard J. Miron ◽  
Reinhard Gruber
Keyword(s):  
Target Genes ◽  
Nuclear Translocation ◽  
Kinase Inhibitor ◽  
Plasma Layer ◽  
Buffy Coat ◽  
Type I ◽  
Platelet Rich Fibrin ◽  
Nadph Oxidase 4 ◽  
Coat Layer ◽  
The Impact

Liquid platelet-rich fibrin (PRF) can be prepared by high centrifugation forces separating the blood into a platelet-poor plasma (PPP) layer and a cell-rich buffy coat layer, termed concentrated PRF (C-PRF). Heating the liquid PPP was recently introduced to prepare an albumin gel (Alb-gel) that is later mixed back with the concentrated liquid C-PRF to generate Alb-PRF. PRF is a rich source of TGF-β activity; however, the overall TGF-β activity in the PPP and the impact of heating the upper plasma layer remains unknown. Here, we investigated for the first time the in vitro TGF-β activity of all fractions of Alb-PRF. We report that exposure of oral fibroblasts with lysates of PPP and the buffy coat layer, but not with heated PPP, provoked a robust increase in the TGF-β target genes interleukin 11 and NADPH oxidase 4 by RT-PCR, and for IL11 by immunoassay. Consistent with the activation of TGF-β signaling, expression changes were blocked in the presence of the TGF-β receptor type I kinase inhibitor SB431542. Immunofluorescence and Western blot further confirmed that lysates of PPP and the buffy coat layer, but not heated PPP, induced the nuclear translocation of Smad2/3 and increased phosphorylation of Smad3. The immunoassay further revealed that PPP and particularly BC are rich in active TGF-β compared to heated PPP. These results strengthen the evidence that not only the cell-rich C-PRF but also PPP comprise a TGF-β activity that is, however, heat sensitive. It thus seems relevant to mix the heated PPP with the buffy coat C-PRF layer to regain TGF-β activity, as proposed during the preparation of Alb-PRF.

scholarly journals Long-Term Comparison of Attraction of Flying Insects to Streetlights after the Transition from Traditional Light Sources to Light-Emitting Diodes in Urban and Peri-Urban Settings

2019 ◽  
Vol 11 (22) ◽  
pp. 6198 ◽  
Author(s):  
Roy H. A. van Grunsven ◽  
Julia Becker ◽  
Stephanie Peter ◽  
Stefan Heller ◽  
Franz Hölker
Keyword(s):  
Light Emitting Diodes ◽  
Spectral Composition ◽  
Mercury Vapor ◽  
World Market ◽  
Relative Difference ◽  
Urban Setting ◽  
Light Sources ◽  
Urban Settings ◽  
Light Emitting ◽  
The Impact

Among the different light sources used for street lighting, light-emitting diodes (LEDs) are likely to dominate the world market in the coming years. At the same time, the spectral composition of nocturnal illumination is changing. Europe and many other areas worldwide have implemented bans on energy-inefficient lamps, such as the still very common mercury vapor lamps. However, the impact of artificial light on insects is mostly tested with light-traps or flight-intercept traps that are used for short periods only. By comparing the numbers of insects attracted by street lamps before and after replacing mercury vapor light sources (MV) with light emitting diodes, we assessed the impact in more typical (urban and peri-urban) settings over several years. We found that LED attracted approximately half of the number of insects compared to MV lights. Furthermore, most insect groups are less drawn by LED than by MV, while Hymenoptera are less attracted by MV than by LED. Thus, the composition of the attracted communities differed between the light sources, which may impact ecosystem processes and functions. In green peri-urban settings more insects are attracted than in an urban setting, but the relative difference between the light sources is the same.

scholarly journals Influence of macroclumping on type II supernova light curves

2019 ◽  
Vol 629 ◽  
pp. A17
Author(s):  
Luc Dessart ◽  
Edouard Audit
Keyword(s):  
Light Curve ◽  
Early Time ◽  
Radiation Energy ◽  
Mean Free Path ◽  
Light Curves ◽  
Type Ii ◽  
Different Temperatures ◽  
Curve Modeling ◽  
2D And 3D ◽  
The Impact

Core-collapse supernova (SN) ejecta are probably structured on both small and large scales, with greater deviations from spherical symmetry nearer the explosion site. Here, we present 2D and 3D gray radiation hydrodynamics simulations of type II SN light curves from red and blue supergiant star explosions to investigate the impact of inhomogeneities in density or composition on SN observables, with a characteristic scale set to a few percent of the local radius. Clumping is found to hasten the release of stored radiation, boosting the early time luminosity and shortening the photospheric phase. Around the photosphere, radiation leaks between the clumps where the photon mean free path is greater. Since radiation is stored uniformly in volume, a greater clumping can increase this leakage by storing more and more mass into smaller and denser clumps containing less and less radiation energy. An inhomogeneous medium in which different regions recombine at different temperatures can also impact the light curve. Clumping can thus be a source of diversity in SN brightness. Clumping may lead to a systematic underestimate of ejecta masses from light curve modeling, although a significant offset seems to require a large density contrast of a few tens between clumps and interclump medium.

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