Fraction Of Radiation Research Articles

Shedding light on the increased carbon uptake by a boreal forest under diffuse solar radiation across multiple scales.

Solar radiation is scattered by cloud cover, aerosols and other particles in the atmosphere, all of which are affected by global changes. Furthermore, the diffuse fraction of solar radiation is increased by more frequent forest fires and likewise would be if climate interventions such as stratospheric aerosol injection were adopted. Forest ecosystem studies predict that an increase in diffuse radiation would result in higher productivity, but ecophysiological data are required to identify the processes responsible within the forest canopy. In our study, the response of a boreal forest to direct, diffuse and heterogeneous solar radiation conditions was examined during the daytime in the growing season to determine how carbon uptake is affected by radiation conditions at different scales. A 10-year data set of ecosystem, shoot and forest floor vegetation carbon and water-flux data was examined. Ecosystem-level carbon assimilation was higher under diffuse radiation conditions in comparison with direct radiation conditions at equivalent total photosynthetically active radiation (PAR). This was driven by both an increase in shoot and forest floor vegetation photosynthetic rate. Most notably, ecosystem-scale productivity was strongly related to the absolute amount of diffuse PAR, since it integrates both changes in total PAR and diffuse fraction. This finding provides a gateway to explore the processes by which absolute diffuse PAR enhances productivity, and the long-term persistence of this effect under scenarios of higher global diffuse radiation.

Predictors of Tumor Dynamics Over a 6-Week Course of Concurrent Chemoradiotherapy for Glioblastoma and the Effect on Survival

We present the final analyses of tumor dynamics and their prognostic significance during a 6-week course of concurrent chemoradiotherapy for glioblastoma in the Glioblastoma Longitudinal Imaging Observational study. This is a prospective serial magnetic resonance imaging study in 129 patients with glioblastoma who had magnetic resonance imaging obtained at radiation therapy (RT) planning (F0), fraction 10 (F10), fraction 20 (F20), and 1-month post-RT. Tumor dynamics assessed included gross tumor volume relative to F0 (Vrel) and tumor migration distance (dmigration). Covariables evaluated included: corpus callosum involvement, extent of surgery, O6-methylguanine-DNA-methyltransferase methylation, and isocitrate dehydrogenase mutation status. The median Vrel were 0.85 (range, 0.25-2.29) at F10, 0.79 (range, 0.09-2.22) at F20, and 0.78 (range, 0.13-4.27) at 1 month after completion of RT. The median dmigration were 4.7 mm (range, 1.1-20.4 mm) at F10, 4.7 mm (range, 0.8-20.7 mm) at F20, and 6.1 mm (range, 0.0-45.5 mm) at 1 month after completion of RT. Compared with patients who had corpus callosum involvement (n = 26), those without corpus callosum involvement (n = 103) had significant Vrel reduction at F20 (P = .03) and smaller dmigration at F20 (P = .007). Compared with patients who had biopsy alone (n = 19) and subtotal resection (n = 71), those who had gross total resection (n = 38) had significant Vrel reduction at F10 (P = .001) and F20 (P = .001) and a smaller dmigration at F10 (P = .03) and F20 (P = .002). O6-Methylguanine-DNA-methyltransferase methylation and isocitrate dehydrogenase mutation status were not significantly associated with tumor dynamics. The median progression-free survival and overall survival (OS) were 8.5 months (95% CI, 6.9-9.9) and 20.4 months (95% CI, 17.6-25.2). In multivariable analyses, patients with Vrel ≥ 1.33 at F10 had worse OS (hazard ratio [HR], 4.6; 95% CI, 1.8-11.4; P = .001), and patients with dmigration ≥ 5 mm at 1-month post-RT had worse progression-free survival (HR, 1.76; 95% CI, 1.08-2.87) and OS (HR, 2.2; 95% CI, 1.2-4.0; P = .007). Corpus callosum involvement and extent of surgery are independent predictors of tumor dynamics during RT and can enable patient selection for adaptive RT strategies. Significant tumor enlargement at F10 and tumor migration 1-month post-RT were associated with poorer OS.

Overview of advances in ASDEX Upgrade plasma control to support critical physics research for ITER and beyond

The successful operation of fusion reactors requires plasma scenarios with good core confinement and acceptable first wall heat loads that are stable and robust to external perturbations. This poses both physical and technological challenges. One of the technologies that addresses these challenges is a complex feedback control system that supports advances in physical understanding and helps to ensure stable operating conditions. The operation of marginally stable plasmas often leads to off-normal events (such as disruptions) and feedback control can prevent these to some extent. This contribution gives an overview of the main results of the development and operation of the feedback control algorithms on ASDEX Upgrade (AUG). Fueling actuators, using a combination of gas valves and pellet injection, can simultaneously control neutral density of the divertor and the density of the plasma core above the Greenwald limit. Impurity injection is employed to control the position of the X-point radiator, allowing the creation of an ELM-suppressed H-mode with high radiation fraction. Heating actuators are used to control the plasma energy content, which supports advanced tokamak experiments and enables stable I-mode operation, and the electron temperature control, which supports turbulence studies. In control technology, AUG has pioneered the use of virtual actuators, which allow effective use of the limited number of heating actuators, adaptive control policies, and exception handling. Such technologies will also be used in ITER. Advanced nonlinear state observers (RAPTOR, RAPDENS) and codes to evaluate the power deposition properties (RABBIT, TORBEAM) are available for routine use in the AUG feedback controllers. Extensive use of the AUG discharge control system further enhances the research capabilities of this machine.

Characteristics of proliferation and apoptosis of hepatocytes after administration of ascorbic acid in a model of radiation hepatitis

BACKGROUND: Radiation hepatitis with the development of radiation-induced acute liver failure is considered one of the most serious complications of radiotherapy for malignant neoplasms of the liver, abdominal organs, or whole body irradiation. However, the exact mechanisms of radiation-induced liver cell death have not been fully elucidated, and therefore the study of changes in the proliferative-apoptotic ratio in liver structures remains relevant, and pre-irradiation administration of ascorbic acid can potentially protect them from the effects of electron irradiation.
 AIM: assessment of proliferation and apoptosis of hepatocytes after administration of ascorbic acid in a model of radiation hepatitis.
 METHODS: Wistar rats (Rattus Wistar; n=40) were divided into four experimental groups: I – control (n=10); II (n=10) – fractional irradiation with electrons in a total irradiation dose of 30 Gy; III (n=10) – administration of ascorbic acid before electron irradiation; IV (n=10) – administration of ascorbic acid. Animals of all groups (I – IV) were removed from the experiment a week after the last fraction. Morphological and immunohistochemical (with antibodies to Ki-67 and caspase-3) studies were carried out.
 RESULTS: A week after electron irradiation, a sharp decrease in the proportion of Ki-67-positive hepatocytes in combination with an increase in immunolabeling with antibodies to caspase-3 was observed in group II. During the administration of ascorbic acid in group III, less pronounced depth and range of liver damage was noted, confirmed by morphological and immunohistochemical methods (less pronounced decrease in the level of Ki-67 expression and an increase in the proportion of caspase-positive hepatocytes compared to the control) methods.
 CONCLUSION: An immunohistochemical study of proliferation and apoptosis of hepatocytes revealed that a week after fractional electron irradiation in SOD 30 Gy, there is a decrease in mitotic activity and an increase in cell death, and pre-irradiation administration of ascorbic acid helped level out the detected changes, which indicates its protective effect.

Diffuse Fertilization Effect in Maize and Soybean Is Driven by Improved Light Use Efficiency Rather Than by Light Absorption

AbstractDiffuse radiation can improve the efficiency of terrestrial carbon uptake. Both light absorption and canopy light use efficiency (LUE) are affected by the fraction of diffuse radiation (DF). However, the relative contribution of these two factors to the diffuse fertilization effect (DFE) in the short term is not well understood. To investigate the mechanism of DFE in cropland, we collected gross primary productivity, fraction of absorbed photosynthetically active radiation (FAPAR), and other meteorological parameters from June to August in three crop sites. Our results indicated that the short‐term DFE in soybean and maize was primarily driven by the improvement of LUE rather than light absorption. The LUE increased significantly with DF, while the FAPAR changed a little with DF. The increased DF is typically associated with reduced photosynthetically active radiation (PAR). Our results showed that the potential gain in light absorption and canopy LUE from DF could not fully offset the reduced PAR in soybean and maize. The findings in this study contribute to our understanding of the mechanisms underlying the DFE.

Technical note: Workload and transmission data for mobile C-arm fluoroscopy in gastrointestinal endoscopy.

Mobile C-arms may be used in fixed locations, and it is recommended that qualified experts evaluate structural shielding. To assess clinical workload distributions for mobile C-arms used in gastrointestinal endoscopy and determine the Archer equation parameters for the C-arm beam spectra. Consecutive (30 months) gastrointestinal endoscopic procedures on two Cios Alpha systems (Siemens) were retrospectively analyzed. X-ray tube voltage, tube current-time product, reference point air kerma (Ka,r), air kerma-area product (PKA), and fluoroscopic time were examined. The primary beam half-value layer (HVL) was measured with an ionization chamber and aluminum 1100 plates. Stray radiation fraction at 1m from a scattering source (ACR R/F phantom) was directly measured. Monte Carlo (Geant4) simulation was performed to calculate the transmission of broad X-ray beams through lead, concrete, gypsum, and steel, with X-ray HVLs matching those of the C-arm X-ray beam. The transmission data were fitted to the Archer equation. The number of procedures (3509) was equivalent to 13.48 procedures per room per week. Dose quantities were 54.8 mGy (Ka,r), 18.3Gy∙cm2 (PKA), and 7.8 min (fluoroscopic time) per procedure. X-ray beam irradiation events were recorded for 2906 (82.8%) procedures with 160,009 events, whose mA-minute weighted tube voltage was 91.0kV and the workload was 0.68mA-minute per procedure. The two rooms had a significant difference in the number of procedures per week, 17.3 (29) [mean (maximum)] and 9.6 (16), respectively. The stray radiation fraction was 9.7×10-4 (80kV) and 1.25×10-3 (120kV). Transmission fitting parameters were provided for the tube voltage (on average, 90kV; high end, 120kV) of the C-arm. This work provides workload and transmission data for mobile C-arm fluoroscopy in gastrointestinal endoscopy, which indicates a need for structural shielding evaluation of the procedure rooms.

Dual solutions of Darcy-Forchheimer radiative-convective magneto-nanofluid flow over an exponentially stretching/shrinking surface: Stability and entropy generation analysis

A numerical investigation was conducted to examine the existence of dual solutions over exponentially stretching or shrinking permeable surfaces. The study aimed to analyze the impact of thermal and second-order velocity slip on magnetohydrodynamic (MHD) mixed convective radiative nanofluid flow within a Darcy-Forchheimer porous medium while considering heat generation. Two distinct types of nanofluids, namely Cu-water and TiO 2/water, were employed in the investigation. To address the nonlinear partial differential equations (PDEs), similarity transformations were utilized to transform them into a system of ordinary differential equations (ODEs). The resulting coupled higher-order nonlinear ODEs were then solved using a MATLAB-based boundary value algorithm known as bvp4c. Two distinct solutions are observed within a restricted range of the stretching/shrinking parameter ξ ( ξ > ξ c ) and suction parameter S ( S > S c ), terminating respectively at ξ = ξ c or S = S c . The critical values are identified as ξ c = − 1.1952 ( Cu − water ) , − 0.9304 ( Ti O 2 − water ) and S c = 1.6437 ( Cu − water ) , 1.8900 ( Ti O 2 − water ) , maintaining the fixed values of the remaining physical parameters. Notably, the critical value for Cu-water is lower than that of TiO 2-water. Moreover, in both solution branches, the range of skin-friction coefficient and local Nusselt number for Cu-water surpasses that of TiO 2-water. An evaluation of the temporal stability of these solutions reveals that only the first solution remains stable. This is supported by the positivity of the smallest eigenvalues ( γ 1 > 0 ), indicating stability. Conversely, for the second solution, the smallest eigenvalues ( γ 1 < 0 ) are negative, signifying its instability. Also, Cu-water nanofluid exhibits higher fluid velocity and lower fluid temperature than TiO 2-water nanofluid for stable solutions and the opposite behavior for unstable solution branches. Significantly, within the initial solution branch, there is an escalation in velocity profiles attributed to the magnetic parameter, Grashof number, porous parameter, and first- and second-order velocity slip parameter. Conversely, a decrease is observed for the Forchheimer number, while the opposite holds true for the second solution branch. For both solution branches, the temperature profiles experience a reduction due to thermal slip and stretching/shrinking parameters, whereas enhancements are noted for thermal radiation and heat generation parameters. Furthermore, an increase in the suction parameter leads to elevated skin friction coefficient and local Nusselt number in the first stable solution, thereby promptly improving heat transfer efficiency. Moreover, improvements in entropy generation arise from factors such as thermal radiation, magnetic field, and nanoparticle solid volume fraction, presenting opportunities to optimize heat transmission in cooling and heating systems.

Radiative MHD Boundary Layer Flow and Heat Transfer Characteristics of Fe-Casson Base Nanofluid over Stretching/Shrinking Surface

In this paper, there is considered MHD boundary layer flow and heat transfer characteristics of Fe-Casson base nanofluid over an exponentially stretching/shrinking surface along the heat source/sink and Newtonian heating effects. In this regard, to develop the system of the governing equations, the one phase model named as Tiwari and Das model is considered with iron nanoparticles. The non-linear governing PDEs are first changed into the system of ODEs using suitable similarity transformations. Later on, the equations are solved numerically by using bvp4c in Matlab software. Effects of certain physical parameters on skin friction coefficient and the local Nusselt number are illustrated graphically. Moreover, the velocity and temperature profiles are examined to observe the influence of various physical parameters such as, Casson, magnetic, suction, radiation, Newtonian heating, heat source/sink and the nanoparticles volume fractions. It is seen that an increase in Casson, magnetic, suction and the nanoparticle volume fractions decrease the velocity profiles for both shrinking and shrinking cases of surface. The temperature profile recedes due to augmentation of Prandlt number and the suction parameter for both stretching/shrinking case while increases with increase in Magnetic, radiation and nanoparticles volume fractions.

MHD unsteady flow of carbon nanotubes over nonlinear radiative surface with anisotropic slip conditions: computational analysis of irreversibility for Yamada-Ota model

In this study, the Yamada-Ota model is used to look for an analysis of irreversibility when there is nonsymmetric magnetohydrodynamic flow inside a nanoliquid made of carbon nanotubes (CNTs) across an unsteady three-dimensional stretching surface. In this investigation, both single- and multi-walled carbon nanotubes (SWCNTs and MWCNTs, respectively) are considered, as they are both suspended in a water solution. Anisotropic slip conditions, nonlinear thermal radiation, and an induced magnetic field are all accounted for in the model. The PDEs are changed into a group of nonlinear Equations using the non-similarity transformations and then solved by using the BVP4c program in MATLAB. The effects of important parameters like magnetic field strength, unsteadiness, nanoparticle volume fraction, slip conditions and nonlinear thermal radiation are also looked at. Increasing the nanoparticle volume percentage results in a greater velocity field for SWCNTs than for MWCNTs. The profile of entropy production exhibits an upward trend in relation to the parameters Φ, M , Br, Rd and θ w , however, it has a downward trend in relation to the parameter α. The Bejan number profile shows an upward trend in the concentration of α, while showing a decline in the cases of Φ, M , Br, Rd and θ w .

Morphofunctional characteristics of the pancreas after N-acetylcysteine administration in an acute postradiation pancreatitis model

BACKGROUND: The development of effective nondrug and drug-based methods for protecting humans and animals from the effects of ionizing radiation remains important. A morphofunctional assessment of changes in the pancreatic parenchyma is required to determine the degree of radiosensitization of acinar cells and islet cells outside the tumor and during electron treatment of cancer of nearby organs, such as the colon and stomach.&#x0D; AIM: Morphofunctional assessment of the pancreas after N-acetylcysteine administration in a model of acute radiation-induced pancreatitis.&#x0D; MATERIALS AND METHODS: Wistar rats (Rattus Wistar; n=40) were divided into three experimental groups: control group I (n=10); II (n=10) — fractional irradiation with electrons in a total dose of 25 Gy; III (n=10) — administration of N-acetylcysteine before electron irradiation; and IV (n=10) — administration of N-acetylcysteine. A week after the last fraction, animals from all groups were removed from the experiment.&#x0D; RESULTS: A week after electron irradiation, a disruption in histoarchitecture was found in group II due to signs of acute postradiation pancreatitis. Increases in glucose, amylase, and malondialdehyde levels were associated with decreases in insulin and superoxide dismutase levels. In group III, the depth and range of damage to the pancreas were less evident with N-acetylcysteine administration.&#x0D; CONCLUSIONS: After a week of local irradiation with electrons at a total irradiation dose of 25 Gy, the histoarchitecture of the pancreas is disrupted, resulting in acute postradiation pancreatitis. N-acetylcysteine reduces the depth and range of radiation-induced damage while increasing the effectiveness of antioxidant protection.

Consolidative thoracic radiation therapy for extensive-stage small cell lung cancer in the era of first-line chemoimmunotherapy: preclinical data and a retrospective study in Southern Italy.

Consolidative thoracic radiotherapy (TRT) has been commonly used in the management of extensive-stage small cell lung cancer (ES-SCLC). Nevertheless, phase III trials exploring first-line chemoimmunotherapy have excluded this treatment approach. However, there is a strong biological rationale to support the use of radiotherapy (RT) as a boost to sustain anti-tumor immune responses. Currently, the benefit of TRT after chemoimmunotherapy remains unclear. The present report describes the real-world experiences of 120 patients with ES-SCLC treated with different chemoimmunotherapy combinations. Preclinical data supporting the hypothesis of anti-tumor immune responses induced by RT are also presented. A total of 120 ES-SCLC patients treated with chemoimmunotherapy since 2019 in the South of Italy were retrospectively analyzed. None of the patients included in the analysis experienced disease progression after undergoing first-line chemoimmunotherapy. Of these, 59 patients underwent TRT after a multidisciplinary decision by the treatment team. Patient characteristics, chemoimmunotherapy schedule, and timing of TRT onset were assessed. Safety served as the primary endpoint, while efficacy measured in terms of overall survival (OS) and progression-free survival (PFS) was used as the secondary endpoint. Immune pathway activation induced by RT in SCLC cells was explored to investigate the biological rationale for combining RT and immunotherapy. Preclinical data supported the activation of innate immune pathways, including the STimulator of INterferon pathway (STING), gamma-interferon-inducible protein (IFI-16), and mitochondrial antiviral-signaling protein (MAVS) related to DNA and RNA release. Clinical data showed that TRT was associated with a good safety profile. Of the 59 patients treated with TRT, only 10% experienced radiation toxicity, while no ≥ G3 radiation-induced adverse events occurred. The median time for TRT onset after cycles of chemoimmunotherapy was 62 days. Total radiation dose and fraction dose of TRT include from 30 Gy in 10 fractions, up to definitive dose in selected patients. Consolidative TRT was associated with a significantly longer PFS than systemic therapy alone (one-year PFS of 61% vs. 31%, p<0.001), with a trend toward improved OS (one-year OS of 80% vs. 61%, p=0.027). Multi-center data from establishments in the South of Italy provide a general confidence in using TRT as a consolidative strategy after chemoimmunotherapy. Considering the limits of a restrospective analysis, these preliminary results support the feasibility of the approach and encourage a prospective evaluation.

Comparative Characterisation of Proliferation and Apoptosis of Colonic Epithelium after Electron Irradiation with 2 GY and 25 GY.

Development of new techniques for multimodal treatment and diagnostics of various neoplasms and the improvement of current techniques can significantly increase the life expectancy of patients with carcinomas of the colon and abdominal-cavity organs, since prevention of various side effects of radiation therapy is one of the main problems of oncological care. Electron irradiation is one of the most promising types of radiation therapy. There are no data on proliferation and apoptosis of the colon epithelium after irradiation with electrons, especially in different modes (single and summary). Morphological evaluation of apoptosis and proliferation of colonic epithelium after local irradiation with electrons were conducted at doses of 2 Gy (Gray) and 25 Gy. Colon fragments from sexually mature Wistar rats (n = 50, body weight 200 ± 10 g) were divided into three groups: I-control (n = 10); II-experimental group (n = 20; local single electron irradiation at a dose of 2 Gy); III-experimental group (n = 30) with local fractional irradiation with electrons at a total dose of 25 Gy. They were studied using light microscopy using hematoxylin and eosin staining and immunohistochemical reactions with antibodies to Ki-67 and caspase-3 (Cas3). Morphological disorders were accompanied by increased expression of pro-apoptotic molecules (caspase-3), and the period of regeneration by proliferative marker (Ki-67). Colon electron irradiation led to disturbances in the histoarchitecture of varying severity, and an increase in cell apoptosis was observed (increased expression of caspase-3 and decrease in Ki-67). In addition, modulation of the PI3K/AKT and MAPK/ERK signalling pathways was detected. The most pronounced destructive changes were observed in the group of 25 Gy fractionated electron irradiation.

The Difference between the Responses of Gross Primary Production and Sun-Induced Chlorophyll Fluorescence to the Environment Based on Tower-Based and TROPOMI SIF Data

The strong correlation between gross primary production (GPP) and sun-induced chlorophyll fluorescence (SIF) has been reported in many studies and is the basis of the SIF-based GPP estimation. However, GPP and SIF are not fully synchronous under various environmental conditions, which may destroy a stable GPP–SIF relationship. Therefore, exploring the difference between responses of GPP and SIF to the environment is essential to correctly understand the GPP–SIF relationship. As the common driver of GPP and SIF, the incident radiation could cause GPP and SIF to have similar responses to the environment, which may obscure the discrepancies in the responses of GPP and SIF to the other environmental variables, and further result in the ambiguity of the GPP–SIF relationship and uncertainties in the application of SIF. Therefore, we tried to exclude the dominant role of radiation in the responses of GPP and SIF to the environment based on the binning method, in which continuous tower-based SIF, satellite SIF, and eddy covariance GPP data from two growing seasons were used to investigate the differences in the responses of GPP and SIF to radiation, air temperature (Ta), and evaporation fraction (EF). We found that the following: (1) At both the site and satellite scales, there were divergences in the light response speeds between GPP and SIF which were affected by Ta and EF. (2) SIF and its light response curves were insensitive to EF and Ta compared to GPP, and the consistency in GPP and SIF light responses was gradually improved with the improvement of Ta and EF. (3) The dynamic slope values of the GPP–SIF relationship were mostly caused by the different sensitivities of GPP and SIF to EF and Ta. Our results highlighted that GPP and SIF were not highly consistent, having differences in environmental responses that further confused the GPP–SIF relationship, leading to complex SIF application.

Differential Distribution of the DNA-PKcs Inhibitor Peposertib Selectively Radiosensitizes Patient-derived Melanoma Brain Metastasis Xenografts.

Radioresistance of melanoma brain metastases limits the clinical utility of conventionally fractionated brain radiation in this disease, and strategies to improve radiation response could have significant clinical impact. The catalytic subunit of DNA-dependent protein kinase (DNA-PKcs) is critical for repair of radiation-induced DNA damage, and inhibitors of this kinase can have potent effects on radiation sensitivity. In this study, the radiosensitizing effects of the DNA-PKcs inhibitor peposertib were evaluated in patient-derived xenografts of melanoma brain metastases (M12, M15, M27). In clonogenic survival assays, peposertib augmented radiation-induced killing of M12 cells at concentrations ≥100 nmol/L, and a minimum of 16 hours exposure allowed maximal sensitization. This information was integrated with pharmacokinetic modeling to define an optimal dosing regimen for peposertib of 125 mpk dosed just prior to and 7 hours after irradiation. Using this drug dosing regimen in combination with 2.5 Gy × 5 fractions of radiation, significant prolongation in median survival was observed in M12-eGFP (104%; P = 0.0015) and M15 (50%; P = 0.03), while more limited effects were seen in M27 (16%, P = 0.04). These data support the concept of developing peposertib as a radiosensitizer for brain metastases and provide a paradigm for integrating in vitro and pharmacokinetic data to define an optimal radiosensitizing regimen for potent DNA repair inhibitors.

Numerical investigation of increasing the efficiency of thermal photovoltaic system by changing the level of heat transfer distribution

In photovoltaic systems, only a small fraction of solar radiation effectively reaches the module's surface and is converted into electrical energy. The unused solar radiation results in elevated cell temperature and reduced electrical efficiency. In the photovoltaic-thermal system, the circulation of fluids such as water or air around the panels allows for the utilization of otherwise wasted thermal energy, leading to increased electrical efficiency and overall system efficiency. The objective of this article is to examine the thermal efficiency of copper and aluminum oxides in photovoltaic systems when combined with nanofluid. The aim is to identify any changes in efficiency that may arise from this combination. This article presents a novel approach by employing a combination of aluminum oxide and copper nanofluids, along with a water mixture, to investigate the influence of key factors on the electrical, thermal, and overall efficiency of photovoltaic systems. These factors encompass incoming radiation levels on the panel surface, fluid inlet temperature in mountainous regions, and absorber temperature. The study aims to analyze and compare the thermal efficiency of copper and aluminum oxide in this particular context. In the present study, the finite volume method is used to solve the equations. According to the research findings, raising the initial temperature of the incoming fluid results in a proportional increase in the outlet temperature. However, it is important to note that the thermal efficiency remains constant regardless of changes in the initial fluid temperature. Furthermore, copper oxide exhibits superior thermal efficiency compared to aluminum oxide, and the use of nanofluids enhances the thermal efficiency of photovoltaic systems.

Computational insights into shape effects and heat transport enhancement in MHD-free convection of polar ternary hybrid nanofluid around a radiant sphere

The control and management of energy and their associated issues are increasingly recognized as one of mankind’s greatest challenges in the coming years to keep pace with the surge in industrialization and technology. Free convection optimizes the heat transfer processes in energy systems like solar collectors and power plants, reducing energy consumption and increasing system effectiveness. Further, studying and analyzing critical factors like magnetic fields, thermal radiation, and the shape of nanoparticles can assist in the control of fluid motion and improve the efficiency of heat transfer processes in a wide range of real-world applications, such as the power sector, aerospace applications, molten metal, nuclear power, and aeronautical engineering. This study aims to scrutinize the thermal performance of a magneto tri-hybrid polar nanoliquid flowing over a radiative sphere, considering the nanosolids’ shape. The single-phase model is developed to acquire the problems governing equations, and the hybrid linearization spectral collection approach is utilized to approximate the solution. The present findings reveal that blade-shaped nanosolids exhibit the highest thermal conductivity ratio when incorporated into the base fluid, whereas spherical nanosolids exhibit the lowest ratio. Volume fraction and thermal radiation factors have an effective role in raising fluid velocity and thermal performance. The magnetic and microapolar factors significantly suppress fluid velocity and energy transfer. As the volume fraction factor increases, the average percentage improvement in convective heat transfer for Al2O3 + Cu + MWCNT/kerosene oil compared to Al2O3 + Cu + graphene/kerosene oil approximately ranges from 0.8 to 2.6%.

Covering Factor of the Dust-Driven Broad-Line Region Clouds

The origin of the broad-line region (BLR) clouds in active galactic nuclei is still under discussion. We develop a scenario in which the clouds in the outer, less ionized part of the BLR are launched by the radiation pressure acting on dust. Most of the outflow forms a failed wind, so we refer to it as failed radiatively accelerated dusty outflow (FRADO), but, for a certain parameter range, actual outflow also takes place. We aim to test the model predictions. In this paper, we present the calculation of the angular distribution of clouds and the net covering factor as this affects the fraction of radiation that can be intercepted and reprocessed in the form of the Hβ or Mg II emission line. The results reveal that the covering factor is intricately linked to the mass, accretion rate, and metallicity of the clouds. Notably, as these parameters increase, so does the covering factor, shedding light on the dynamic interplay between the central engine and the surrounding material in AGNs.

Влияние облучения на заболевания крови среди участников ликвидации последствий аварии на Чернобыльской атомной электростанции с учётом мультиморбидности состояний пациентов

The statistical relationships between radiation doses and blood diseases with the account of the multimorbidity factor in the Russian cohort of workers involved in mitigation of the consequences of the accident at the Chernobyl NPP have been investigated. For analysis observation data accumulated from 1986 over 2022 kept in the National Radiation Epidemiological Register were used. The size of the liquidators cohort was 89,578 men. During the follow-up period 6,013 blood disorders (D50-D89 ICD-10) were detected for the first time. The average radiation dose in the cohort was 0.13 Gy, and the average age at the first exposure was 33.6 years. Common approaches to data mining (Data Mining) were used to identify statistical relationships between blood diseases and other diseases; for radiation risk assessment, logistic regression models were used to link disease probability to radiation dose. The effect of low-dose radiation (less than 0.3 Gy) on blood diseases is statistically significant and is characterized by a multiplicative linear no-threshold model, the dose-response model with ERR/Gy=0.59 at 95% CI (0.23; 0.99). When considering multimorbidity in patients, the blood diseases radiation risk change was not statistically significant. Radiation risks several times higher than risks of malignant neoplasms, were found in three groups of diseases: 1) blood and haemopoietic organs other than anaemia and hemorrhages (D70-D77), with ERR/Gy=2.25; 2) immunodeficiency states (D80-D89), with ERR/Gr=2.01; 3) aplastic anemias (D60-D61), with ERR/Gy=5.56. The inclusion of aplastic anaemia in the officially approved list of diseases caused by exposure to ionizing radiation in Russia should be considered as scientifically justified document. The list may need to be supplemented by diseases of blood and haemorrhagic organs other than anaemia and hemorrhage, as well as immunodeficiency conditions. The radiation risk coefficients (ERR/Gy) for the main groups of blood diseases estimated for the first time will make it possible to establish radiation dependence in exposed people with the use of a dose and radiation-epidemiological approach, estimating the attributive fraction of radiation in the etiology of each specific disease case.

Моделирование теплового потока пожара пролива в программном комплексе PyroSim

Purpose. This article discusses the configuration of parameters in the PyroSim software, which play a significant role in modeling thermal flows during a pool fire. The results of thermal flow calculations in PyroSim are compared with experimental results obtained by other researchers. Methods. Mathematical modeling methods in the PyroSim software were used, as well as comparison of physical modeling results of a pool fire with mathematical modeling results. Findings. The results of a pool fire modeling in PyroSim are influenced by such parameters as the lower heating value of the substance, the flame radiation fraction coefficient, the mass burning rate of the substance, and the division of the burning surface by the computational grid. Research application field. The results of the study can be used when modeling pool fires in the PyroSim software. Conclusions. The article highlights settings that require special attention during pool fire modeling in PyroSim, as they significantly impact thermal flow values. It is recommended to use a flame radiation fraction coefficient of 0.15 when modeling pool fires with diameters up to 10 meters.

Therapeutic pathomorphosis of stage IB–IIA cervical cancer cells after various regimens of preoperative HDR brachytherapy

Background. Despite of the constant improvement of existing treatment methods, involving the latest technologies into the treatment programs, the results of the treatment remain unsatisfactory. It is impossible to prevent the dissemination of tumor cells during surgery, which cause the tumor recurrence. Even in case of early stage cervical cancer, after only adequate conducted surgery, the relapse-rate is 20–30%, and the five-year survival rate is 40–60%. The aim of the work is to evaluate the effectiveness of different doses of preoperative HDR-brachytherapy in cervical cancer patients stage IB–IIA, based on the data of therapeutic pathomorphosis of the tumor. Materials and methods. There was investigated the structural and functional status of cells of squamous cell cervical cancer stage IB–IIA in two treatment schemes. According to the first scheme, there was conducted two sessions of brachytherapy with a single dose of 5 Gy with an interval of 7 days, up to the common dose of 10 Gy (5+5 Gy). According to another scheme, the single dose at the first session was 7 Gy, at the second session – 5 Gy, total dose was 12 Gy. The comparison group included primary patients with squamous cell cervical cancer and patients, who received fractional EBRT and EBRT + LDR-brachytherapy, total dose of 20 Gy and 40 Gy respectively. The morphofunctional status of cancer cells was investigated using standard electron microscopy methods. In all studied groups, there was detected the frequency of tumors samples, which contain large cells, the frequency of tumors with the presence of mitoses, and frequency of cases with significant therapeutic pathomorphosis. The obtained data was processed by the application of non-parametric statistical methods, using the «Biostat» software, and non-parametric criterion of the most plausible reliability assessment for small selections. Results. It is established that 26.9% of primary patients with cervical cancer had tumors with large cancer cells. After fractional irradiation with total doses of 20 and 40 Gy, an increase in the frequency of cases of tumors with such cells to 37.5 and 50.0%, respectively, was observed although these changes were unreliable in comparison with the control group of primary patients. However, after the first session of HDR-brachytherapy in a single dose of 5 or 7 Gy, in contrast to the indicators in the group of primary patients, there was a sharp and reliable increase in the frequency of tumors cases with large cancer cells up to 83.3% and 90%, respectively. At the same time, pronounced therapeutic pathomorphosis did not exceed 10.0–16.7% of cases. The second session of HDR brachytherapy at a dose of 5 Gy (total doses of 10 and 12 Gy) led both to a decrease in the frequency of tumors with large cancer cells to the level of control values (20 and 27.3%), and to a dose-dependent increase in the indicators of pronounced therapeutic pathomorphosis ( 40 and 70% respectively). Conclusions. There has been established that HDR-brachytherapy with the initial single dose of 5 or 7 Gy initiate a significant reaction, when the primary population of cancer cells is replaced by others, where prevail their large forms, which may be giant polyploid cancer cells. After the second session of brachytherapy of 5 Gy, the proportion of tumors, which are composed of large cells, significantly decreases simultaneously with the increase of significant therapeutic pathomorphosis in the cellpopulation of cervical cancer. The application of HDR-brachytherapy of 7 Gy at the first session will lead to the higher efficacy of the proposed scheme of the preoperative irradiation in cervical cancer patients stages IB–IIA, when the therapeutic pathomorphosis reaches 70%, when at the same time with a total dose of brachytherapy of 10 Gy, therapeutic pathomorphosis is only 40%.