ARTICLE | doi:10.20944/preprints202107.0653.v1
Subject: Engineering, Automotive Engineering Keywords: Fluidization; Radioactive Particle Tracking; Information Geometry; Stability Criteria
Online: 29 July 2021 (12:20:07 CEST)
Currently, various industrial processes are carried out in fluidized bed reactors, such as fermentation, water treatment, and algae growth. Knowing its internal dynamics is fundamental for the intensification of these processes. This work assesses the motion of fluidized calcium alginate spheres under the influence of an upward fluid flow within a 1.2 m high and 0.1 m inner diameter acrylic column. The Radioactive Particle Tracking technique is a proper methodology to study the internal dynamics of these kinds of equipment. Liquid-Solid Fluidized Bed is compared with the Gas-Liquid-Solid Fluidized Bed operation mode in terms of mixing behavior. Data gathered is analyzed in view of Shannon entropy as a dynamic mixing measure. Mixing times are found to be of the same order of magnitude. However, the Liquid-Solid Fluidized Bed achieves a lower homogenization degree. Also, we found good agreement between two criteria for assessing stability for the mixed state: the Shannon Entropy time-series plateau and the Glansdorff-Prigogine criterion based on Fisher information.
ARTICLE | doi:10.20944/preprints202207.0188.v1
Subject: Physical Sciences, Radiation & Radiography Keywords: recycling; radioactive waste; radioactive nanopowders; radioactive nanocomposites; radioactive semiconductor devices; radioactive space microelectronics; space industry
Online: 12 July 2022 (10:08:57 CEST)
The article provides an overview of nanocomposites and microelectronic elements used in space electronics and radiation control systems of nuclear reactors. Only those nanocomposites and microelectronic elements are taken into account that improve their characteristics in radiation fields or remain indifferent when exposed to ionizing radiation. Considering the chemical composition of the materials of these nanocomposites and microelectronic elements, it is analyzed from which radioactive materials (RM) obtained by recycling radioactive waste (RW) such composites and microelectronic parts can be made. Thus, an alternative way of radioactive waste disposal is proposed, when these wastes are used in the form of microelectronic elements designed to operate under conditions of cosmic radiation.
ARTICLE | doi:10.20944/preprints202205.0198.v1
Subject: Physical Sciences, Radiation & Radiography Keywords: radioactive waste; radioactive waste recycling; industrial slag; industrial ash; aerospace industry
Online: 16 May 2022 (07:50:42 CEST)
The article discusses an alternative way of recycling radioactive waste (RW), presented in the form of radioactive building materials - concrete and reinforced concrete structures and metal fittings, with the further use of materials, obtained during recycling, in the space industry. That is, it is supposed to send radioactive waste into space not as a passive ballast, but as a payload that will operate in space under conditions of increased radiation.
ARTICLE | doi:10.20944/preprints201710.0024.v1
Subject: Earth Sciences, Geology Keywords: aquifer, rock, radioactive isotopes, groundwater dating
Online: 4 October 2017 (16:45:54 CEST)
Uranium isotopes actively investigated as mechanistic or time scale tracers of natural processes. This paper describes the occurrence and redistribution of U in the Vendian aquifer of the paleo valley at NW Russia. Forty-four rock samples were collected from boreholes, and twenty-five groundwater samples. The U, Fe concentration, and 234U/238U activity ratio were determined in the samples. We estimated the 14C and 234U-238U residence time of groundwater in an aquifer. It has been established that the processes of chemical weathering of Vendian deposits led to the formation of a strong oxidation zone, developed above -250 m.a.s.l. The inverse correlation between the concentrations of uranium and iron is a result of removal of U from paleo valley slopes in oxidizing conditions and accumulation of U at the bottom of the paleo valley in reducing conditions, and accumulation of Fe on the slopes and removal from bottom. Almost all U on the slopes replaced by a newly formed hydrogenic U with a higher 234U/238U activity ratio. After that dissolution and desorption of hydrogenic U was occurred from the slopes during periods without any glaciations and marine transgressions. Elevated concentrations of U preserved in not oxidized lenses at the paleo valley bottom.
REVIEW | doi:10.20944/preprints202010.0159.v1
Subject: Medicine & Pharmacology, Oncology & Oncogenics Keywords: Thyroid carcinoma; non-coding RNA; radioactive iodine; drug resistance; prognosis
Online: 7 October 2020 (14:28:40 CEST)
Thyroid cancer is the most prevalent malignancy of the endocrine system and the ninth most common cancer globally. Despite the advances in the management of thyroid cancer, there are critical issues with the diagnosis and treatment of thyroid cancer that result in the poor overall survival of undifferentiated and metastatic thyroid cancer patients. Recent studies have revealed the role of different non-coding RNAs (ncRNAs), such as microRNAs (miRNAs), long non-coding RNAs (lncRNAs) and circular RNAs (circRNAs) that are dysregulated during thyroid cancer development or the acquisition of resistance to therapeutics, and may play key roles in treatment failure and poor prognosis of the thyroid cancer patients. Here, we systematically review the emerging roles and molecular mechanisms of ncRNAs that regulate thyroid tumorigenesis and drug response. We then propose the potential clinical implications of ncRNAs as novel diagnostic and prognostic biomarkers for thyroid cancer.
ARTICLE | doi:10.20944/preprints201807.0586.v1
Subject: Engineering, Electrical & Electronic Engineering Keywords: Positron emission tomography, Prediction of radioactive injection dosage, PET image, Monte Carlo Simulation.
Online: 30 July 2018 (11:53:42 CEST)
An important aspect of PET imaging in clinical application is the localization and detection of tumors and lesions by administering a predetermined amount of radiotracer. This allows for example, a detailed view of what is going inside the patient body in cellular level. The quality of PET image is strongly dependent on the amount of administrated radiotracer and the patient’s body parameters. As the amount of injection radiotracer increases, the quality of resulting image increases and the lesion detection efficiency increases. The PET examiner society recognizes that any dose of radiotracer is associated with some possible radiation risks. It can harmful to the patient if essential PET imaging session is not made due to fear of radiation risk. In order to ensure the highest quality diagnosis and the smallest radiation risk, the patient should receive the smallest amount of radiotracer that provide image with sufficient quality. Our study is focused on proposing an efficient PET simulation tool that predict the smallest possible amount of administrated radiotracer to provides the appropriate diagnostic information based on significant patient’s body parameters (weight, age) at fixed scanning to improve the clinical diagnostic process in term of tumor detecting and localization. We have built a model of particular PET scanner and model of patient based on real MRI image and digital anthropomorphic phantom of our region of interest (brain). We have performed Monte Carlo simulation for whole PET procedure with special parameter In evaluating stage, a dataset of 60 patient is used and 11 independent dose prediction simulation for each patient are performed. We conclude that our simulator perform a desirable and efficient prediction of injection radiotracer amount that optimizes the current clinical amount up to 28%. In addition, we found that the total injected radiotracer dosage for adult patients are mostly affected when considering patient weight rather than patient age.
ARTICLE | doi:10.20944/preprints202005.0418.v1
Subject: Earth Sciences, Geology Keywords: geological risk; pre-Neogene basement; radioactive waste; waste disposal; Northern Croatia; Probability of Success (PoS)
Online: 26 May 2020 (04:11:18 CEST)
The basic principles of geological risk calculation through Probability of Success (PoS) are mostly applied for numerical estimation of additional hydrocarbon existence in proven reservoirs or potential hydrocarbon discoveries in selected geological regional subsurface volume. It can be tailored and validated for a comprehensive input dataset collected in the selected petroleum province, adapted by dividing up geological events into several probability categories and classes. The most applied categories are (existence of) reservoir rocks, traps and isolators, source rocks, migration pathways and preservation conditions for hydrocarbons The methodology results in unique probability values as multiplication of independent statistical events, which can also be applied in the assessment of a potential hydrocarbon discovery of desired minimal volume and its value in any virtual currency like risk-neutral dollars. Such methodology has been extensively developed in the last decades in the Croatian subsurface, mostly in the Croatian part of the Pannonian Basin System (CPBS). Through the adaptation of geological categories, it was also applied in hybrid, i.e., stochastical, models developed in the CPBS (Drava Depression). Stochastically estimation of porosity was already applied. As the robustness of this methodology is very high, it was also modified to estimate the influence of water-flooding in increasing oil recovery in some proven Neogene sandstone reservoirs in the CPBS (Sava Depression). This new modification is being presented to be applied to geological risk calculation, intending to assess the safety of geological environment in deep wells, where depleted radioactive fuel would be disposed, a subject of great importance. The case study encompassed the magmatic and metamorphic rocks in the pre-Neogene basement of the CPBS. For disposal purpose, these are regionally lithologies considered as to be the safest ones considering petrophysical values, water saturation, recent weathering and tectonic activity.
ARTICLE | doi:10.20944/preprints202103.0157.v1
Subject: Engineering, Automotive Engineering Keywords: Coating; Light extraction; Nanostructure; Optical interface; Packing fraction; PET; Photonic crystals; Radioactive source; Scintillators; Thin films
Online: 4 March 2021 (12:28:18 CET)
Scintillators play a key role in the detection chain of several applications which rely on the use of ionizing radiation, and it is often mandatory to extract and detect the generated scintillation light as efficiently as possible. In positron emission tomography (PET), for example, both energy resolution and coincidence resolving time, two of the key detection parameters, depend strongly on the total amount of light which reaches the photodetector surface as well as its spatial and temporal distribution. Typical inorganic scintillators do however feature a high index of refraction, which impacts light extraction efficiency in a negative way. Furthermore, several applications such as preclinical PET rely on pixelated scintillators with small pitch. In this case, applying reflectors on the crystal pixel surface, as done conventionally, can have a dramatic impact of the packing fraction and thus the overall system sensitivity. This paper presents a study on light extraction techniques, as well as combinations thereof, for two of the most used inorganic scintillators (LYSO and BGO). Novel approaches, employing distributed Bragg reflectors (DBRs), metal coatings, and a modified Photonic Crystal (PhC) structure, are described in detail and compared with commonly used techniques. The nanostructure of the PhC is surrounded by a hybrid organic/inorganic silica sol-gel buffer layer which ensures robustness while maintaining its performance unchanged. We observed in particular a maximum light gain of about 41% on light extraction and 21% on energy resolution for BGO, a scintillator which has gained interest in the recent past due to its prompt Cherenkov component and lower cost.