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Qualification of the ANET Code for Spallation Neutron Yield and Core Criticality in the KUCA ADS

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World Journal of Nuclear Science and Technology 2019年第4期9卷 174-181页

作者： Xenofontos Thalia panayiota savva Melpomeni Varvayanni Jacques Maillard Jorge Silva Marc-Thierry Jaekel Nicolas Catsaros Institute of Nuclear and Radiological Sciences & Technology Energy & Safety National Centre for Scientific Research Demokritos Aghia Paraskevi Greece Laboratoire de Physique de l’Ecole Normale Supérieure CNRS Paris France.

Innovative nuclear reactor concepts such as the Accelerator Driven Systems (ADSs) have imposed extra requirements of simulation capabilities on the existing stochastic neutronics codes. The combination of an accelerator and a nuclear reactor in the ADS requires the simulation of both subsystems for an integrated system analysis. Therefore, a need arises for more advanced simulation tools, able to cover the broad neutron energy spectrum involved in these systems. ANET (Advanced Neutronics with Evolution and Thermal hydraulic feedback) is an under development stochastic code for simulating conventional and hybrid nuclear reactors. Successive testing applications performed throughout the ANET development have been utilized to verify and validate the new code capabilities. In this context, the ANET reliability in simulating the spallation reaction and the corresponding neutron yield as well as computing the multiplication factor of an operating ADS are here examined. More specifically, three cores of the Kyoto University Critical Assembly (KUCA) facility in Japan were analyzed focusing on the spallation neutron yield and the neutron multiplication factor. The ANET-produced results are compared with independent results obtained using the stochastic codes MCNP6.1 and MCNPX. Satisfactory agreement is found between the codes, confirming thus ANET’s capability to successfully estimate both the neutron yield of the spallation reaction and the keff of a realistic ADS.

关键词： Monte Carlo Neutronics Analysis Code Validation Accelerator Driven Systems

A real-world data collection framework for a fused dataset creation for joint human and remotely operated vehicle monitoring and anomalous command detection

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CAAI Transactions on Intelligence Technology 2022年第3期7卷 432-445页

作者： Rafaella Elia George Plastiras Eva Pettemeridou Antonis savva Theocharis Theocharides Department of Electrical and Computer Engineering University of CyprusNicosiaCyprus KIOS Research and Innovation Center of Excellence University of CyprusNicosiaCyprus Center for Applied Neuroscience(CAN) University of CyprusNicosiaCyprus

Unmanned Remotely Operated Vehicles(ROVs)are widely used in safety-critical missions,spanning across monitoring,surveillance,and search and rescue *** most cases,the human operator controls the ROV under stressful conditions and in harsh *** physical and mental states of the operator are vital as they may cause involuntary movements,issuing unintentional commands due to fatigue or ***,a joint monitoring mechanism that will assess the operator's commands can be beneficial in preventing potentially catastrophic events,such as *** this end,in this study,we propose a data collection framework for creating a fused dataset,consisting of data obtained from both the human operator and the ROV,and we integrate stress induction to stimulate stress and fatigue that may affect operators during *** optimise the dataset,which includes the operator's physiological signals and inertial measurement unit(IMU)sensor data from the ROV,using data fusion approaches and feature *** evaluate the dataset through the statistical analysis,illustrating a statistical difference between data characterising normal and involuntary ***,we evaluate the optimised and original datasets over a variety of classifiers,demonstrating an accuracy of 94%and 95%,respectively.

关键词： operator fused operators

On the Origin of the Apparent Volume of Distribution and Its Significance in Pharmacokinetics

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Journal of Biosciences and Medicines 2022年第1期10卷 78-98页

作者： Michalakis savva South University Savannah USA

The apparent volume of distribution was defined for the first time as the phase volume that can hold the total amount of a substance at the measured phase substance concentration, in a system composed of two immiscible media that are in contact under conditions of constant phase volumes, at equilibrium. Its value is not affected by the total system solute mass and it only depends on the total system volume, the phase volumes and the affinity of the solute for the two phases in the system. Using this new concept of the apparent volume of distribution, we were able to demonstrate that under certain conditions compartment volumes in multi-compartment and multi-phasic pharmacokinetic models represent the actual physiological volumes of body fluids accessible by drugs. The classical pharmacokinetic models are now fully explained and can be used to provide accurate estimation of the pharmacokinetic parameters for hydrophilic drugs. In contrast, in the absence of tissue-plasma partition coefficients, lipophilic drugs that do not follow a one-compartment model are unlikely to be adequately described with classical multi-compartment pharmacokinetic models.

关键词： Apparent Volume of Distribution Partition Coefficient Phase Extraction Pharmacokinetic Compartmental Modeling Physiologically-Based Pharmacokinetic Modeling

The Presence of Phases and the Inability of the Classical Compartment Models to Provide Pharmacokinetic Parameters of Physiological Significance for Lipophilic Drugs

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Journal of Biosciences and Medicines 2022年第4期10卷 1-13页

作者： Michalakis savva South University Savannah USA

The first biphasic open one-compartment pharmacokinetic model is described. Its analytical solutions to drug concentration were developed from parameters of an open two-compartment pharmacokinetic model. The model is used to explain the unusually large compartment volumes and apparent volumes of distribution of lipophilic drugs, as well as to identify which of the pharmacokinetic parameters of the classical compartment models are biologically relevant.

关键词： Lipophilic Drugs Pharmacokinetic Compartment Model Apparent Volume of Distribution Clearance Prazosin Doxazosin Digoxin Pindolol

Real-Time Analytical Solutions as Series Formulas and Heaviside off/on Switch Functions for Multiple Intermittent Intravenous Infusions in One- and Two-Compartment Models

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Journal of Biosciences and Medicines 2022年第1期10卷 150-189页

作者： Michalakis savva South University Savannah USA

Pharmacokinetic compartment models are the only models that can extract pharmacokinetic parameters from data collected in clinical studies but their estimates lack accuracy, explanations and physiological significance. The objective of this work was to develop particular solutions to drug concentration and AUC in the form of mathematical series and Heaviside functions for repetitive intermittent infusions in the one- and two-compartment models, as a function of dose number and total time using differential calculus. It was demonstrated that the central and peripheral compartment volumes determined from regression analysis of the aminoglycoside antibiotic Sisomicin concentration in plasma represent the actual physiological body fluid volumes accessible by the drug. The drug peak time and peak concentration in the peripheral compartment were also calculated as a function of dose number. It is also shown that the time of intercompartmental momentary distribution equilibrium can be used to determine the drug’s apparent volume of distribution within any dosing interval in multi-compartment models. These estimates were used to carry out simulations of plasma drug concentration with time in the one-compartment model. In conclusion, the two-compartment open mammillary pharmacokinetic model was fully explained for the aminoglycoside antibiotic sisomicin through the new concept of the apparent volume of distribution.

关键词： Pharmacokinetics Intermittent Intravenous Infusion Multiple Doses Compartment Models Heaviside Function Apparent Volume of Distribution

A Reevaluation of Prazosin Pharmacokinetics in a Two-Compartment Model, the Apparent Volume of Distribution and Comparative Simulations in the One-Compartment Model

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Journal of Biosciences and Medicines 2022年第1期10卷 108-140页

作者： Michalakis savva Xudong Yuan South University Savannah USA Acon Pharmaceuticals Cranbury USA

Published clinical data of Prazosin were reevaluated pharmacokinetically using explicit solutions to drug concentration as a function of total time for IV bolus injection, intermittent intravenous infusion and oral routes of administration in an open two-compartment model. In a novel way, the apparent volume of distribution was estimated from a two-compartment model and found to be close to the total body water suggesting that Prazosin is distributed in all tissues both extracellularly and intracellularly. In addition, extracting the value of the apparent volume of distribution from a two-compartment model allowed comparative simulations in the one-compartment model. It is shown that dosage calculations of Prazosin intermittent infusion can be safely performed using the simpler one-compartment model equations. Lastly, several additional time-dependent pharmacokinetic parameters e.g., the peak time in the central and peripheral compartment and non-steady state and steady state peak concentration and AUC were determined using series equations for all three routes of administration, as a function of dose number and total time upon multiple drug administrations in the two-compartment model. It is also the first time that steady-state plasma drug concentration equations were derived in a two-compartment mammillary model.

关键词： Prazosin Pharmacokinetics Intravenous Bolus Intermittent Infusion Oral Dose Multiple Doses Compartment Model Apparent Volume of Distribution

Gupeiite Body in the Siberian Taiga (the Zone of Passage of the Tunguska Meteorite and the Vitim Bollid)

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Natural Resources 2022年第2期13卷 53-64页

作者： Natalya Evgenievna savva Pavel Sergeevich Minyuk Tatiana Vladimirovna Subbotnikova Federal State Budgetary Institution North-Eastern Integrated Research Institute Named after N.A. Shilo of the Far Eastern Branch of the Russian Academy of Sciences Magadan Russia

Many years have passed since the two cosmic bodies of the Tunguska meteorite and the Vitim bollid fell to Earth, but so far the substance of these bodies has not been found on Earth. Therefore, each metal body found on the territory of their passage is of particular interest. The body of iron silicide weighing 12 kg was studied, which was accidentally discovered by a hunter of the village of Kyker in the Siberian taiga on the right bank of the Nercha River, Tungokochensky district, Trans-Baikal Territory. Coordinates of the place of discovery are: 53º19'N lat, 116º19'E long. The territory is located in the zone of the passage of the Tunguska meteorite and the Vitim bollid, 25 km from the hunting village of Green Lake. The body is named “Ilekta” after the nearest stream flowing into the Nercha River. The composition and magnetic properties of the exotic find have been determined. It is established that its main mass is composed of iron silicide, gupesiite Fe3Si (zussite?) and contains inclusions of needle-like rhabdite. On the surface, the body is covered with a melting crust, with signs of boiling, a bubbly structure and a film of clay minerals of terrestrial origin. In the molten porous crust, eutectic-schreibersite-gupeiite is observed, and rare titanium carbide crystals are also noted. The magnetic susceptibility of the samples is not uniform (286.6 - 461.8 10-6E-06 m3/kg). It is assumed that a drop of melt separated from the flying space body, and experienced overheating and boiling of the surface layer in the dense layers of the atmosphere.

关键词： Gupeiite Melting Crust Cosmos Tunguska Meteorite

Reconstruction of the Indigenous Sources of Gold of the Glu-Kharinsky Placer (Kolyma River Basin, Magadan Region, Russia)

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Natural Resources 2022年第12期13卷 225-241页

作者： Natalya Evgenievna savva Aleksandr Aleksandrovich Biruykov Anton Nikolaevich Gluhov Shilo North-East Interdisciplinary Scientific Research Institute Far Eastern Branch of the Russian Academy of Sciences Magadan Russia

A comparative analysis of typomorphic features of gold placers and indigenous sources of gold was carried out for the Glukharinsky ore-placer node (the Nadezhda deposit and Glukharinskoye, Tyomnoye, and Tyi-Jurye ore occurrences). A correlation between fineness of placer native gold and composition of relic minerals preserved inside gold particles was obtained for the first time. This made it possible to establish mineral parageneses of native gold from potential indigenous sources. The study of placer gold fineness in combination with com-position of mineral inclusions allowed us to identify seven types of gold paragenesis: petzite-hessite with a fineness of 855‰, pyrite-polybasite-galena (a fineness of 670‰), bismuth telluride (900‰), cosalite-vikingite (790‰), galena (870‰), glaucodot (950‰), and hydrohematite (840‰). It was also shown that the placer contains the material from ore occurrences of different formation: gold-quartz-porphyry occurrences in granitoids (Au-Te-Bi type) and gold-silver occurrences. The method developed by us allows one to estimate the percentage of each ore source in placer formation.

关键词： Ore-Placer Node Native Gold Mineral Associations Placer Indigenous Sources

Ionization and transfection activity of n-methyl-substituted carbamoyl-cholesterol derivatives

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Journal of Biophysical Chemistry 2011年第2期2卷 53-62页

作者： Samuel Acheampong Michalakis savva Division of pharmaceuticals Sciences Arnold & Marie Schwartz College of Pharmacy & Health Sciences Long Island University New York United States

Five novel cationic lipids, the polar head group of which was attached to the cholesterol backbone via a tertiary carbamate linker, were synthesized and their physicochemical properties were compared to their transfection efficiencies. Transfection activity of the primary amine analog was highest among the series, while the quaternary ammonium iodide salt was essentially transfection incompetent. Contrary to DC-Chol, methyl and ethyl carbamoyl derivatives of DC-Chol mediated high levels of transfection in the absence of DOPE. Ionization of the cationic assemblies in 40 mM Tris buffer pH 7.2 exactly correlated with the competitive nature of the inductive and steric effects of the methyl groups on the aliphatic nitrogen of the lipids’ polar moiety. Interestingly, the pH interaction zone of all lipid dispersions at 25°C was extended by ± 2 pH units from the pKa, while the pKa of the cationic lipids determined in mixed vesicles composed of 90 % DOPC and cholesterol was approximately 1.3 to 1.5 times higher than that of pure cationic assemblies. The interaction of cationic lipids with plasmid DNA was correlated with pKa, but not the transfection activity.

关键词： Cationic Lipids DC-Chol Transfection Pka Plasmid DNA Monolayer Surface Pressure.