radiation energy density
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2022 ◽  
Vol 1049 ◽  
pp. 11-17
Author(s):  
Ivan Kaplunov ◽  
Taras Malinskiy ◽  
S.I. Mikolutskiy ◽  
Vladimir Rogalin ◽  
Yuriy Khomich ◽  
...  

We investigated the process of laser heat treatment of polished brass samples (36% zinc, containing a small amount of lead, which does not dissolve in the alloy and is in the form of inclusions, having micron and submicron size) by impacting to a series of 25 - 30 ultraviolet (UV) pulses of a Nd:YAG laser (third harmonic, wavelength λ = 355 nm, duration τ = 10 ns, pulse repetition rate f = 10 Hz, pulse energy density ~ 0.15 - 1.0 J/cm2) in the stationary spot mode. Copper and its alloys absorb up to 90% of the energy of this laser. It is found that the relaxation of the absorbed energy of laser radiation in the metal occurs nonuniformly. Defects in the metal structure such as grain boundaries and lead inclusions are visualized. Traces of crystallographic sliding appear inside some grains. With an increase in the number of impacting impulses, accumulation of damage is observed. A further increase in the radiation energy density leads to an aggravation of the observed phenomena.


2022 ◽  
Vol 92 (2) ◽  
pp. 268
Author(s):  
Т.В. Малинский ◽  
В.Е. Рогалин

The prethreshold processes on the surface of copper and its alloys are investigated. In the absence of obvious traces of melting, while preserving the metal in a condensed state, under a nanosecond ultraviolet laser radiation energy density of 0.1–1.0 J/cm2, manifestations of high-temperature plastic deformation were observed. These are sliding and cracking along grain boundaries, within which crystallographic slipping was observed. A microprotrusion was formed on the surface of the irradiated zone, which was outwardly similar the distribution of laser radiation in the spot. The height of the microprotrusion reached 1 µm, and sometimes even more. An increase in the number of impacting impulses led to the accumulation of damage. The data obtained are in many ways similar to the acoustoplastic, electroplastic, and magnetoplastic effects. By analogy, we consider it possible to call the discovered effect optoplastic.


2021 ◽  
Vol 2086 (1) ◽  
pp. 012011
Author(s):  
A V Kuksin ◽  
U E Kurilova ◽  
O E Glukhova ◽  
E M Eganova ◽  
A A Dudin ◽  
...  

Abstract Materials containing conductive CNT networks were investigated in this work. Binding of CNTs to each other was carried out using laser radiation in scanning mode. As a result of experimental studies, radiation energy density at which the effect of SWCNT binding occured was found – 0.061 J/cm2. Mechanism by which formation of porous materials with SWCNTs in composition takes place has been established. Materials from CNTs and biopolymers with controllable pore sizes that make up more than 60% of nanocomposite volume have been made.


2021 ◽  
Vol 922 (2) ◽  
pp. 192
Author(s):  
Axel Brandenburg ◽  
Yutong He ◽  
Ramkishor Sharma

Abstract Using numerical simulations of helical inflationary magnetogenesis in a low reheating temperature scenario, we show that the magnetic energy spectrum is strongly peaked at a particular wavenumber that depends on the reheating temperature. Gravitational waves (GWs) are produced at frequencies between 3 nHz and 50 mHz for reheating temperatures between 150 MeV and 3 × 105 GeV, respectively. At and below the peak frequency, the stress spectrum is always found to be that of white noise. This implies a linear increase of GW energy per logarithmic wavenumber interval, instead of a cubic one. Both in the helical and nonhelical cases, the GW spectrum is followed by a sharp drop for frequencies above the respective peak frequency. In this magnetogenesis scenario, the presence of a helical term extends the peak of the GW spectrum and therefore also the position of the aforementioned drop toward larger frequencies compared to the case without helicity. This might make a difference in it being detectable with space interferometers. The efficiency of GW production is found to be almost the same as in the nonhelical case, and independent of the reheating temperature, provided the electromagnetic energy at the end of reheating is fixed to be a certain fraction of the radiation energy density. Also, contrary to the case without helicity, the electric energy is now less than the magnetic energy during reheating. The fractional circular polarization is found to be nearly 100% in a certain range below the peak frequency range.


2021 ◽  
Vol 2064 (1) ◽  
pp. 012092
Author(s):  
A E Ligachev ◽  
M V Zhidkov ◽  
S A Sorokin ◽  
G V Potemkin ◽  
Yu R Kolobov

Abstract Effect of the pulsed soft X-ray fluxes (PSXF) on the surface topography of metals (Mg and Cu) has been investigated. Soft pulse X-ray irradiation (energy quanta of 0.1-1.0 keV) were carried out on a high-current MIG generator. The sample of magnesium was located at a distance of 10 cm from the X-ray source. Since the distance to the sample significantly exceeded the size of the X-ray beam, it can be assumed that the density of the X-ray radiation flow to the magnesium sample was uniform. The duration of the radiation pulse was 100 ns, and the radiation energy density in the pulse varied from 13 to 19 J/cm2. As a result of melting under the action of PSXF of the near-surface layer of metals and subsequent solidification, a wavy relief is formed on their surface. Defects in the form of craters, which usually occur after the impact of a powerful pulsed ion flow on metals, were not detected.


2021 ◽  
Vol 10 (3) ◽  
pp. 12-22
Author(s):  
O. B. Abramova ◽  
V. V. Drozhzhina ◽  
T. P. Churikova ◽  
E. A. Kozlovtceva ◽  
L. M. Arkhipova ◽  
...  

The article summarizes the results of studies of the effectiveness of photodynamic therapy using a new domestic photosensitizer liposomal borated chlorin e6 (LBC) after its parenteral administration (intraperitoneal and intravenous). Antitumor efficacy was evaluated in rats with M-1 sarcoma and PC-1 alveolar liver cancer and mice with B16 melanoma and Ehrlich’s carcinoma, which were transplanted subcutaneously into the thigh area of the animals. The aim of the study was to determine the optimal regimes of photodynamic therapy that would allow achieving the maximum antitumor effect up to 21 days after the photodynamic therapy. The therapy was carried out under the control of the accumulation of the photosensitizer in the tumor and surrounding tissues of the thigh by selecting the doses of the drug and the parameters of laser radiation (energy density and power density). The effectiveness of therapy was assessed by the inhibition of tumor growth, by the percentage of animals with complete tumor regression, by the absolute growth rate in animals with continued tumor growth compared to controls. The results of our studies have shown that the domestic photosensitizer liposomal borated chlorin e6 has high antitumor activity in vivo. In an experimental study of the photosensitizer under certain PDT modes, the maximum antitumor effect (complete tumor regression in 100% of animals) was obtained up to 21 days after PDT in all tumor models used.


Author(s):  
Alessandro Di Marco ◽  
Gianfranco Pradisi

We explore the consequences of a time-dependent inflaton equation-of-state (EoS) parameter in the context of the post-inflationary perturbative Boltzmann reheating. In particular, we numerically solve the perturbative coupled system of Boltzmann equations involving the inflaton energy density, the radiation energy density and the related entropy density and temperature of the produced particle thermal bath. We exploit reasonable Ansätze for the EoS and discuss the robustness of the Boltzmann system. We also comment on the possible microscopic origin related to a time-dependent inflaton potential, discussing the consequences on a preheating stage and the related (primordial) gravitational waves.


2021 ◽  
Vol 24 (4) ◽  
pp. 54-61
Author(s):  
V. N. Kapinus ◽  
M. A. Kaplan ◽  
E. V. Yaroslavtseva-Isayeva ◽  
I. S. Spichenkova ◽  
A. D. Kaprin ◽  
...  

It is given a literature reference on the etiology, frequency and mechanisms of development, features of the clinical presentation and treatment options for skin cancer that has developed on scars. It is presented a detailed clinical observation of a patient with squamous cell skin cancer in the area of the right elbow joint, which occurred 67 years after the kerosene lamp burns of the skin of the right upper limb and the right half of the chest. The patient was initially treated with electron radiotherapy in the total focal dose 60 Gy with a partial effect, but after 10 months a relapse was diagnosed, for which multi-course photodynamic therapy was performed with a Photolon photosensitizer at a dose of 1.1 mg/kg; the way of light delivery was polypositional interstitial and distant, the laser radiation power density was 0.30 W/cm2, the laser radiation energy density was 200 J/cm2. The result of treatment is complete regression of the tumor, the patient was under regular observation without any signs of local, regional and distant metastasis. After 3 years, by the absence of signs of local relapse, the disease progression was diagnosed: metastatic lesion of the axillary lymph nodes on the right and multiple metastases in the lung tissue of both lungs. Treatment was performed: axillary lymphadenectomy on the right, targeted therapy with IgGl monoclonal antibodies directed against the epidermal growth factor receptor; on this background stabilization of the process was noted.


2021 ◽  
Vol 503 (1) ◽  
pp. 1367-1373
Author(s):  
J Fukue

ABSTRACT Two-dimensional funnel flows driven by radiation pressure in the conical funnel formed by the critical accretion disc are examined using the self-similar treatment. The flow is assumed to be steady and axisymmetric, and other forces such as viscosity and magnetic fields are ignored. For various boundary conditions on the funnel wall at the disc surface, the self-similar solutions are found to be classified into three types: funnel-filled solutions, where the flow gas fills the whole region of the funnel; polar-hollow ones, where there appears a cavity around the polar axis, and unphysical ones in a sense that, e.g. the radiation energy density becomes negative. For the physically reasonable solutions, the flow gas generally concentrates to the funnel wall, and the flow density and the radiation energy density monotonically decrease from the funnel wall towards the polar axis, while the radial flux becomes negative near the polar axis. The vertical velocity increases towards the polar axis, while the vertical flux has often the maximum between the polar axis and the funnel wall. As a result, the present self-similar funnel jets are such a flow with a slow dense outer part and a fast rarefied inner part.


2021 ◽  
Vol 63 (9) ◽  
pp. 1245
Author(s):  
Б.Н. Звонков ◽  
О.В. Вихрова ◽  
Ю.А. Данилов ◽  
П.Б. Демина ◽  
М.В. Дорохин ◽  
...  

InGaAs/GaAs heteronanostructures with a (Ga,Mn)As layer on the surface were fabricated by MOCVD epitaxy and pulsed laser deposition, and the effect of a pulsed excimer laser (wavelength 248 nm, pulse duration ~ 30 ns) on their radiative, structural and galvanomagnetic properties was studied. The radiation energy density was varied in the range from 200 to 360 mJ/cm2. In the studies, photoluminescence spectroscopy was used, which makes it possible to analyze the polarization characteristics of the radiation of the structures. The crystalline perfection of the initial and laser-irradiated samples was studied using Raman spectroscopy. The elemental composition of the structures and its depth distribution were studied by secondary ion mass spectrometry. The effect of pulsed laser annealing on the ferromagnetic properties of heteronanostructures was characterized by the behavior of the magnetic field dependences of the Hall resistance and magnetoresistance at temperatures of 10–300 K in the range of magnetic fields ± 3600 Oe. At room temperature, the study was carried out in magnetic fields reaching values of ± 28000 Oe. To obtain the calculated temperature distributions along the sample thickness and in time using a model of the laser annealing process based on solving the problem of heat propagation in a one-dimensional GaAs system taking into account the (Ga,Mn)As layer on the surface, we used the original data on the thermal conductivity coefficient of structures with a layer (Ga,Mn)As obtained using a modified frequency separation technique (3ω-method).


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