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Analysis of Sustainable Materials for Radiative Cooling Potential of Building Surfaces
摘要： The main goal of this paper is to explore the radiative cooling and solar heating potential of several materials for the built environment, based on their spectrally-selective properties. A material for solar heating, should have high spectral emissivity/absorptivity in the solar radiation band (within the wavelength range of 0.2–2 μm), and low emissivity/absorptivity at longer wavelengths. Radiative cooling applications require high spectral emissivity/absorptivity, within the atmospheric window band (8–13 μm), and a low emissivity/absorptivity in other bands. UV-Vis spectrophotometer and FTIR spectroscopy, are used to measure, the spectral absorption/emission spectra of six different types of materials. To evaluate the radiative cooling potential of the samples, the power of cooling is calculated. Heat transfer through most materials is not just a surface phenomenon, but it also needs a volumetric analysis. Therefore, a coupled radiation and conduction heat transfer analysis is used. Results are discussed for the selection of the best materials, for different applications on building surfaces.
关键词： sustainable materials,coupled radiation-conduction heat transfer,built environment,spectrally-selective surfaces,radiative cooling,roofs
更新于2025-09-23 15:22:29
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Diagnostic imaging and radiation exposure in inflammatory bowel disease
摘要： Diagnostic imaging plays a key role in the diagnosis and management of inflammatory bowel disease (IBD). However due to the relapsing nature of IBD, there is growing concern that IBD patients may be exposed to potentially harmful cumulative levels of ionising radiation in their lifetime, increasing malignant potential in a population already at risk. In this review we explore the proportion of IBD patients exposed to high cumulative radiation doses, the risk factors associated with higher radiation exposures, and we compare conventional diagnostic imaging with newer radiation-free imaging techniques used in the evaluation of patients with IBD. While computed tomography (CT) performs well as an imaging modality for IBD, the effective radiation dose is considerably higher than other abdominal imaging modalities. It is increasingly recognised that CT imaging remains responsible for the majority of diagnostic medical radiation to which IBD patients are exposed. Magnetic resonance imaging (MRI) and small intestine contrast enhanced ultrasonography (SICUS) have now emerged as suitable radiation-free alternatives to CT imaging, with comparable diagnostic accuracy. The routine use of MRI and SICUS for the clinical evaluation of patients with known or suspected small bowel Crohn’s disease is to be encouraged wherever possible. More provision is needed for out-of-hours radiation-free imaging modalities to reduce the need for CT.
关键词： Diagnostic medical radiation,Small intestine contrast-enhanced ultrasonography,Nuclear medicine,Computerised tomography,Inflammatory bowel disease,Magnetic resonance enterography,Small bowel follow-through
更新于2025-09-23 15:22:29
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Ensuring Radiation Resistance of Fiber Optic Gyroscopes and Ways to Improve It
摘要： The problem of ensuring the radiation resistance of fiber-optic gyroscopes and their main components (optical fibers, elements of integrated optics, optical sources, electronic components and optical materials) is analyzed on the basis of Russian and foreign publications. Possible ways of radiation resistance improvement are considered.
关键词： fiber-optic gyro,radiation resistance,review
更新于2025-09-23 15:22:29
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Fluorescent Penetrant Testing by Means of Excilamps
摘要： The paper provides a brief review of modern sources of ultraviolet (UV) radiation used in fluorescent penetrant testing (FT). The differences in implementation of the method with different radiation sources (excilamps, mercury UV lamp and LED UV lamp) are revealed experimentally. It is shown that the XeCl excilamp is not inferior to other sources of UV radiation used in FT.
关键词： Penetrant testing,UV lamp,fluorescent method,LED UV flashlight,ultraviolet radiation,test sample,excilamp
更新于2025-09-23 15:22:29
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Reducing radiation exposure in an electrophysiology lab with introduction of newer fluoroscopic technology
摘要： The use of fluoroscopic devices exposes patients and operators to harmful effects of ionizing radiation in an electrophysiology (EP) lab. We sought to know if the newer fluoroscopic technology (Allura Clarity) installed in a hybrid EP helps to reduce prescribed radiation dose. We performed radiation dose analysis of 90 patients who underwent various procedures in the EP lab at a community teaching hospital after the introduction of newer fluoroscopic technology in June of 2016. Watchman device insertion, radiofrequency ablation procedures, pacemaker permanent (PPM)/implantable cardioverter defibrillator (ICD) placement and battery changes were included in the study to compare radiation exposure during different procedures performed commonly in an EP lab. In all cases of watchman device placement, radiofrequency ablation procedures, PPM/ICD placement and battery changes, there was a statistically significant difference (<0.05) in radiation dose exposure. Significant reduction in radiation exposure during various procedures performed in an EP lab was achieved with aid of newer fluoroscopic technology and better image detection technology.
关键词： watchman device,permanent pacemaker,Radiation exposure,insertable cardioverter defibrillator,electrophysiology lab,newer fluoroscopic system,radiofrequency ablation
更新于2025-09-23 15:22:29
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Robustness of Astrix Fiber Optic Gyros in space radiative environment
摘要： When developing the Fiber Optics Gyro Astrix? family, Airbus and Ixblue faced the problematics of the possible radiation effects on optical and opto-electronics parts. After bibliographic research on the subject, selection of parts was made according to existing knowledge, and batch qualification tests performed to quantify the radiation effects. On-ground test results were introduced in worst case optical budget for the optical loop dimensioning. Several years later, following consequent in-orbit data gathering, we can assess that radiation effect are barely noticeable and that inertial performances remain tremendously stable. The careful design of the Astrix optical loop and the proper selection of opto parts were mastered key factor for such an in-flight success.
关键词： Radiation,Fiber,Optical,Gyroscope,Astrix
更新于2025-09-23 15:22:29
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The Application of a New Model-Based Iterative Reconstruction in Low-Dose Upper Abdominal CT
摘要： Rationale and Objectives: To compare upper abdominal computed tomography (CT) image quality of new model-based iterative reconstruction (MBIR) with low-contrast resolution preference (MBIRNR40), conventional MBIR (MBIRc), and adaptive statistical iterative reconstruction (ASIR) at low dose with ASIR at routine-dose. Materials and Methods: Study included phantom and 60 patients who had initial and follow-up CT scans. For patients, the delay phase was acquired at routine-dose (noise index = 10 HU) for the initial scan and low dose (noise index = 20 HU) for the follow-up. The low-dose CT was reconstructed with 40% and 60% ASIR, MBIRc, and MBIRNR40, while routine-dose CT was reconstructed with 40% ASIR. CT value and noise measurements of the subcutaneous fat, back muscle, liver, and spleen parenchyma were compared using one-way ANOVA. Two radiologists used semiquantitative 7-scale (-3 to +3) to rate image quality and artifacts. Results: The phantom study revealed superior low-contrast resolution with MBIRNR40. For patient scans, the CT dose index for the low-dose CT was 3.00 ± 1.32 mGy, 75% lower than the 11.90 ± 4.75 mGy for the routine-dose CT. Image noise for the low-dose MBIRNR40 images was significantly lower than the low-dose MBIRc and ASIR images, and routine-dose ASIR images (p < 0.05). Subjective ratings showed higher image quality for low-dose MBIRNR40, with lower noise, better low-contrast resolution for abdominal structures, and finer lesion contours than those of low-dose MBIRc and ASIR images, and routine-dose ASIR images (p < 0.05). Conclusion: MBIRNR40 with low-contrast resolution preference provides significantly lower noise and better image quality than MBIRc and ASIR in low-dose abdominal CT; significantly better objective and subjective image quality than the routine-dose ASIR with 75% dose reduction.
关键词： Model-based iterative reconstruction,Abdominal CT.,X-ray computed tomography,Adaptive statistical iterative reconstruction,Radiation dose
更新于2025-09-23 15:22:29
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Radiation dose and image quality in intraoperative CT (iCT) angiography of the brain with stereotactic head frames
摘要： Objectives Intraoperative CT (iCT) angiography of the brain with stereotactic frames is an integral part of navigated neurosurgery. Validated data regarding radiation dose and image quality in these special examinations are not available. We therefore investigated two iCT protocols in this IRB-approved study. Methods Retrospective analysis of patients, who received a cerebral stereotactic iCT angiography on a 128 slice CT scanner between February 2016 and December 2017. In group A, automated tube current modulation (ATCM; reference value 410 mAs) and automated tube voltage selection (reference value 120 kV) were enabled, and only examinations with a selected voltage of 120 kV were included. In group B, fixed parameters were applied (300 mAs, 120 kV). Radiation dose was measured by assessing the volumetric CT dose index (CTDIvol), dose length product (DLP) and effective dose (ED). Signal-to-noise ratio (SNR) and image noise were assessed for objective image quality, visibility of arteries and grey-white differentiation for subjective image quality. Results Two hundred patients (n = 100 in each group) were included. In group A, median selected tube current was 643 mAs (group B, 300 mAs; p < 0.001). Median values of CTDIvol, DLP and ED were 91.54 mGy, 1561 mGy cm and 2.97 mSv in group A, and 43.15 mGy, 769 mGy cm and 1.46 mSv in group B (p < 0.001). Image quality did not significantly differ between groups (p > 0.05). Conclusions ATCM yielded disproportionally high radiation dose due to substantial tube current increase at the frame level, while image quality did not improve. Thus, ATCM should preferentially be disabled.
关键词： Neuronavigation,Brain,Computed tomography angiography,Radiation dosage
更新于2025-09-23 15:22:29
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Defect formation in AlN after irradiation with He2+ ions
摘要： The paper presents results of studies on defect formation processes, radiation resistance, amd changes in the conductive and insulating characteristics of AlN ceramics under irradiation with 40 keV He2+ ions. The radiation fluence ranged from 1015 to 5x1017 ion/cm2. Using the method of X-ray structural analysis, it has been established that an increase in the irradiation fluence leads to a decrease in intensities of diffraction peaks and a change in lines shape, which indicates an increase in the concentration of distortions and stresses in the crystal structure. The change in concentration of deformation in the structure is due to the increase in the content of introduced helium and the formation of cascades of secondary defects and vacancies. At large fluences of irradiation (above 1017 ions/cm2), diffraction patterns show the formation of a halo characteristic of X-ray amorphous or highly disordered impurity inclusions and the formation of spherical inclusions in the surface layer, the average size of which varies from 50 to 100 nm. The decrease in resistance and thermal conductivity as a result of irradiation and the formation of helium inclusions in the structure indicates a degradation of the structural characteristics, as well as a decrease in radiation resistance, which is caused by a drop in strength characteristics.
关键词： ceramics,swelling,radiation embrittlement,defects,structural materials
更新于2025-09-23 15:22:29
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Size dependent radiation-stability of ZnO and TiO2 particles
摘要： ZnO and TiO2 particles are typical pigments used in solar reflective coatings. In this letter, the radiation stability of ZnO and TiO2 particles within submicron (several hundred nm) and nanoscale (30 nm) size is systematically studied. We reported previously that the 90 nm and 300 nm ZnO particles have nearly a same radiation tolerance (Phys. Status Solidi B 2017, 254, 1600411). Unexpectedly, we found herein that the 30 nm oxides have significant higher radiation tolerance in relation to the submicron particles. Detailed analysis illustrated that the abundant native defects and surface/interface states in oxides nanocrystals, in-situ restored radiation damage through rapid diffusion and annihilation with implantation created vacancies. This work would be beneficial for developing nanoscaled oxides and devices used for space and nuclear radiative environments.
关键词： radiation damage,optical properties,TiO2,ZnO
更新于2025-09-23 15:22:29