Kinetic Characteristic Research Articles

Exploration of microscopic physical processes of Z-pinch by a modified electrostatic direct implicit particle-in-cell algorithm

Abstract For investigating efficiently the stagnation kinetic-process of Z-pinch, we develop a novel modified electrostatic implicit particle-in-cell algorithm in radial one-dimension for Z-pinch simulation in which a small-angle cumulative binary collision algorithm is used. In our algorithm, the electric field in z-direction is solved by a parallel electrode-plate model, the azimuthal magnetic field is obtained by Ampere’s law, and the term for charged particle gyromotion is approximated by the cross product of the averaged velocity and magnetic field. In simulation results of 2 MA deuterium plasma shell Z-pinch, the mass-center implosion trajectory agrees generally with that obtained by one-dimensional MHD simulation, and the plasma current also closely aligns with the external current. The phase space diagrams and radial-velocity probability distributions of ions and electrons are obtained. The main kinetic characteristic of electron motion is thermal equilibrium and oscillation, which should be oscillated around the ions, while that of ion motion is implosion inwards. In the region of stagnation radius, the radial-velocity probability distribution of ions transits from the non-equilibrium to equilibrium state with the current increasing, while of electrons is basically the equilibrium state. When the initial ion density and current peak are not high enough, the ions may not reach their thermal equilibrium state through collisions even in its stagnation phase.

Inducing oxygen vacancies using plasma etching to enhance the oxygen evolution reaction activity of the CoMn2O4 catalyst

Spinel-type AB2O4 material has considerable potential as an efficient electrocatalyst in the oxygen evolution reaction (OER). However, developing spinel-type catalysts with higher catalytic activity still faces significant challenges. Herein, we reported an effective strategy to construct abundant oxygen vacancies into the CoMn2O4 (CMO) catalyst using plasma etching, and those oxygen vacancies were capable of enhancing the OER activity of the CMO catalyst. The results showed that the etched CMO catalyst possessed an overpotential of 367 mV at a current density of 10 mA/cm2, and the change overpotential of the etched CMO catalyst was only about half compared to that of the pristine CMO catalyst in a 24-h stability test. The charge transfer ability and reaction kinetic characteristic of the etched CMO catalyst were dramatically improved. Furthermore, the mechanism of oxygen vacancies inducing enhancement of the OER catalytic activity in CMO catalysts has also been elucidated. This work successfully used a defect engineering strategy for modifying the spinel-type catalyst to enhance its OER activity, thereby providing a new idea and method for developing more efficient OER catalysts.

Primary amino acid sequences of decapod (Na+, K+)-ATPase provide evolutionary insights into osmoregulatory mechanisms

Decapod Crustacea exhibit a marine origin, but many taxa have occupied environments ranging from brackish to fresh water and terrestrial habitats, overcoming their inherent osmotic challenges. Osmotic and ionic regulation is achieved by the gill epithelia, driven by two active ATP-hydrolyzing ion transporters, the basal (Na+, K+)-ATPase and the apical V(H+)-ATPase. The kinetic characteristic of gill (Na+, K+)-ATPase and the mRNA expression of its α subunit have been widely studied in various decapod species under different salinity challenges. However, the evolution of the primary structure has not been explored, especially considering the functional modifications associated with decapod phylogeny. Here, we proposed a model for the topology of the decapod α subunit, identifying the sites and motifs involved in its function and regulation, as well as the patterns of its evolution assuming a decapod phylogeny. We also examined both the amino acid substitutions and their functional implications within the context of biochemical and physiological adaptation. The α-subunit of decapod crustaceans shows greater conservation (∼94% identity) compared to the β-subunit (∼40%). While the binding sites for ATP and modulators are conserved in the decapod enzyme, the residues involved in the α-β interaction are only partially conserved. In the phylogenetic context of the complete sequence of (Na+, K+)-ATPase α-subunit, most substitutions appear to be characteristic of the entire group, with specific changes for different subgroups, especially among brachyuran crabs. Interestingly, there was no consistent separation of α-subunit partial sequences related to habitat, suggesting that the convergent evolution for freshwater or terrestrial modes of life is not correlated with similar changes in the enzyme's primary amino acid sequence.

Improvement of Analytical Model for Oblique Cutting—Part I: Identification of Mechanical Characteristics of Machined Material

Analytical cutting models have recently become quite widespread due to the simplicity and rapidity of calculations as well as the stability of the solutions. This paper considers a procedure for determining the mechanical properties of machined material based on parameters for the analytical model of oblique cutting for a certain range of changes in cutting modes and inclination angles of the tool cutting edge. The model is based on the energy method of determining the main cutting process characteristics using the extreme assumptions of continuum mechanics. It is proposed to determine the parameters characterizing the mechanical properties of the processed material using the Johnson–Cook constitutive equation in two stages: preliminary determination of the constitutive equation parameters based on the results of mechanical compression specimen tests and experimental data of the oblique cutting process, and specifying the generalized values of the constitutive equation parameters using the inverse method through the finite element cutting model. The adequacy of the applied analytical cutting model is confirmed by comparing the kinetic characteristic values calculated using the analytical model of oblique cutting with the application of the specified parameters of the constitutive equation and the measured values of the kinetic characteristics. The deviation between the calculated and measured values of the cutting force components when changing the cutting depth (undeformed chip thickness) does not exceed 15%. The difference between the calculated and measured values of the cutting force components when the cutting speed is changed is about 20%.

Straw, biochar, and nanocarbon altered the enzymatic reaction kinetics and thermodynamic process of catalase in the black soil under continuous warming

ABSTRACT Different C influences the kinetic and thermodynamic behavior of catalase (CAT) remains unknown. The study aimed to assess the impact of three different C [straw, biochar, nanocarbon] on kinetic and thermodynamic characteristic of CAT in 5 °C ~ 45 °C. These three C-sources increased Vmax, Vmax/Km, and decreased Km, ΔG, ΔH, ΔS at different temperatures. The addition of nanocarbon induced significant changes in the soil enzymatic characteristics, resulting in the highest soil CAT-activity. After continuous-heating, the addition of three C-sources to the soil increased and then decreased the CAT-activity and its kinetic parameters and their values peaked at 15 °C or 25 °C. On the other hand, the ΔG showed decreasing and then increasing trend and ΔS gradually increased. Q 10 decreased and correlations between CAT and kinetic thermodynamic parameters were observed with increasing-temperature in three C-treatments. There was a significant correlation between soil’s physicochemical properties and soil CAT-activity and their enzymatic reaction characteristics after straw and biochar-treatments. However, an insignificant correlation was observed between the soil indexes after the nanocarbon-treatment. Thus, different C-sources could increase the soil CAT-activity by promoting the enzymatic reaction process under continuous-warming. The continues-warming without any change in the temperature-adaptation of CAT, but its temperature-sensitivity decreased after C-source addition.

Synergistic inhibition of azoles compounds on chloride-induced atmospheric corrosion of copper: Experimental and theoretical characterization

Synergistic implementation of corrosion inhibitors is an efficient and economic method for metal protection. The adsorption dynamics and inhibition behavior of 2-phenyl imidazoline (2-PI) and benzotriazole (BTA) are investigated in atmospheric and aqueous environments by electrochemical and quartz crystal microbalance sensors. Moreover, their synergistic mechanisms are illustrated from molecule scales by theoretical calculations. Electrochemical tests show that 2-PI and BTA exhibit promising synergistic effects on the corrosion of copper with inhibition efficiency up to 99.1% in 0.1 mol/L NaCl solution and 94.1% in the atmosphere, respectively. In addition, the adsorption kinetics of inhibitors on copper obey a pseudo-first-order kinetic model characteristic of exponential damping. Quantum chemical and molecule dynamic calculations also suggest that there exists an intermolecular interaction between 2-PI and BTA molecules in a parallel adsorption manner when they are co-adsorbed on the surface of copper.

Adsorption, regeneration and kinetic of gas phase elemental mercury capture on sulfur incorporated porous carbon synthesized by template method under simulated coal-fired flue gas

A sulfur incorporated porous carbon (SIC) was synthesized by utilizing template method with precursor of 2-thiophene ethanol (C6H8OS) and thymol blue (C27H30O5S). Gas phase elemental mercury capture and regeneration capability of the SIC was explored in a fixed-bed experimental system. Mercury capture product on the SIC was studied by using Hg-TPD experiment. The kinetic parameter, activation energy, and mass transfer characteristic of mercury capture by the SIC was analyzed by using different mathematical models to reveal the mechanism of mercury removal. The results show that the SIC displays excellent mercury capture capability under different flue gas component with adsorption product of HgS. Coexistence of SO2 and H2O in flue gas slightly promotes mercury capture with formation of a small amount of HgSO4. The SIC also exhibits good regeneration ability that after multiple cycles of mercury capture and regeneration, the SIC still keeps a mercury capture rate of 90%. This is because after thermal regeneration, the group of C-S-C on the SIC gets restore and the adsorbed oxidized sulfur is released. Mercury adsorption on the SIC has better thermal stability compared to traditional activated carbon with an adsorption energy of −62.82 kJ/mol, which belongs to chemisorption. Mercury capture on the SIC is firstly dominated by surface adsorption and then converts to internal diffusion adsorption. External mass transfer is mercury adsorption control step and increase of initial mercury concentration promotes global mass transfer mainly via improvement of internal diffusion rate.

Coral-Like Hierarchical Nanostructured ZnMn2O4/Mn2O3 Composites Synthesized by Zinc-Absent Method as a High-Performance Cathode Material for Aqueous Zinc-Ion Batteries

As one of the multivalent ion batteries, the zinc ion battery has the advantages of high-volume energy density and good safety. In this paper, coral-like and nanoparticle crosslinking hierarchical nanostructured ZnMn2O4/Mn2O3 composites were successfully synthesized as cathode materials for zinc ion batteries by a simple sol-gel combined with the zinc-absent method. ZnMn2O4/Mn2O3 composites with good properties were prepared when the zinc content was 10%. The prepared ZnMn2O4/Mn2O3 composites have the morphology of coral-like and nanoparticle crosslinking and uniform particle size distribution. Compared with pure ZnMn2O4 and Mn2O3, the composites show excellent electrochemical properties. Using 0.5 M Zn(CF3SO3)2-AN/H2O (8:2) as the electrolyte, the first discharge capacity of the material can reach 170.7 mAh·g−1 at 0.05 C. After 150 cycles, the discharge capacity remained 109 mAh·g−1. The kinetic characteristic of the electrode was studied by the galvanostatic intermittent titration technique, and the electrochemical reaction mechanism was studied by ex situ XRD. It was found that the two-phase recombination improved the diffusion rate of Zn2+. In the field of aqueous zinc ion batteries, an effective modification idea is provided for the research of spinel ZnMn2O4 cathode material with low specific capacity.

Carbon and oxygen isotope fractionation in the Late Devonian heterocoral Oligophylloides: Implications for the skeletogenesis and evolution of the Heterocorallia

The order Heterocorallia is an enigmatic, anatomically distinct group of calcifying Palaeozoic corals with unclear affinities to other, either extinct or modern cnidarian lineages. Here, we present results of microstructure and stable isotope studies on exceptionally well-preserved skeletons of two species of the heterocoral Oligophylloides from the Famennian (Upper Devonian) of the Anti-Atlas, Morocco and the Holy Cross Mountains, Poland. The investigations provide new information on the skeletogenesis and isotope fractionation effects in Palaeozoic heterocorals. In order to estimate the possible role of diagenetic alteration on the observed carbon and oxygen isotope ratios, we have conducted several preservation tests, including transmitted-light, scanning-electron, fluorescence and cathodoluminescence microscopy, Raman spectroscopy, and trace element analyses. The least- and most-altered skeleton portions identified based on this approach are typified by clearly different isotopic signatures. The least-altered parts of the specimens reveal carbon and oxygen isotope ratios close to those of contemporaneous marine-equilibrated calcites. The moderately-pronounced, positive correlations between the δ13C and δ18O values observed for these coralla may reflect relatively minor vital fractionation effects, obscured to some degree by diagenetic overprint. The results suggest that the isotope fractionation mechanisms of the heterocorals differed markedly from the significant kinetic fractionation characteristic of the modern scleractinian corals. Rather, the moderate, if any, extent of non-equilibrium fractionation during skeletogenesis in the Heterocorallia resembled the typical, environmental and metabolic CO2-dominated fractionation effects shown by most other marine calcifiers. These include the extinct rugose corals, modern hydrocorals and, in particular, modern octocorals, with which the heterocorals show notable architectural and structural similarities.

Mechanical analysis of radial hydraulic force in oil recovery by sliding vane pump

Due to the mechanical structure and operating principle of sliding vane pump (SVP), an all-metal artificial lift equipment with high temperature resistance and high pump efficiency, an unbalanced radial hydraulic force always exists in it during oil recovery, which will cause damage on efficiency, safety and service life of production system. What's more, the flow behavior of fluid through the pump cannot be accurately characterized because current related works fails to capture the influence of the force mentioned. To bridge this knowledge gap, in this paper, the computational fluid dynamics method was introduced and used to analyze the radial hydraulic force under different operating parameters for the first time. On this basis, novel measures to reduce this unbalanced force were put forward, and a design scheme of concentric stator-rotor to completely eliminate the radial hydraulic force was proposed. Main results show that a) increase in eccentricity will contribute to the enhancement of discharge capacity, which will simultaneously aggravate the radial hydraulic force. And this force is proportional to the fluid viscosity, lifting pressure difference and rotation speed. b) The direction of radial hydraulic force of adjacent stages in multistage SVP is opposite. To reduce this unbalanced force, it is recommended to use even-numbered (odd-numbered) multistage pump when the number of total stages is small (large). c) The concentric design eliminates the radial hydraulic force at the expense of the function of self-regulating flow rate. Besides, the stator curve under concentric stator-rotor condition will degrade the kinetic characteristic of vanes.

Experimental Evaluation for the Catalytic Effect of Nickel in Micron Size on Magnesium Hydride

Magnesium hydride is well known as the ideal candidate for solid-state hydrogen storage and thermochemical thermal storage since both gravimetric and volumetric storage are considerably high. The main drawbacks of magnesium hydride are thermodynamic unfavorable and poor kinetic. Adding Nickel as a catalyst, which mainly incorporates mechanical modification (alloying or particle size reduction), can accelerate the reaction rate and decrease the enthalpy formation. It is hard to determine the catalytic of Nickel in magnesium hydride for the kinetic rate improvement. This study is focused on the observation of the effect of Nickel on magnesium hydride by using the market size availability of magnesium and nickel powder (74 μm for Mg and 63 μm for Ni). Mg and Ni are mixed by Ni variation (weight %) from 14%, 15%, and 16%. The characterization starts with initial hydrogenation and dehydrogenation, continues with activation and PCI measurement to obtain the kinetic characteristic of each sample. From this study, it is clear that the increase in nickel ratio will improve the rate of reaction for magnesium hydride, where the maximum storage for magnesium hydride is 4.2% by adding 16 wt% nickel.

Application of model-free and multivariate nonlinear regression methods for evaluation of the kinetic scheme and kinetic parameters of thermal decomposition of low density polyethylene

A sort of low density polyethylene (LDPE) was characterized by X-ray diffraction, X-ray photoelectron spectroscopy (XPS), thermal analysis methods (TG, DTG, DTA) in nitrogen flow at constant heating rates of 2.50, 5.00, 9.91, 14.98 and 19.92 K min−1 and at other five temperature programs, coupled TG + FTIR analysis, and DSC analysis in nitrogen flow. The kinetic analysis of TG data has been performed using an algorithm consisting of the following three successive steps: (1) the application of model-free (isoconversional) methods for evaluation of apparent activation energy dependence on the conversion degree, (2) the processing of the TG data recorded at constant heating rates to assess the possible kinetic schemes and the corresponding kinetic parameters, and (3) the selection of the kinetic scheme characteristic of the thermal decomposition of LDPE by comparing the experimental TG curves with the reconstructed ones corresponding to the temperature programs used. It has been pointed out that the overall process of thermal decomposition of LDPE consists of four successive stages with the Avrami-Erofeev kinetic models (An) - reaction order (Fn) -reaction order (Fn) - three-dimensional diffusion (D3). This kinetic scheme and corresponding kinetic parameters is suitable for prediction of thermal behavior of LDPE in some temperature programs and can be used for the design of pyrolysis reactors necessary for the conversion of LDPE waste into low molecular mass chemicals, which can be used as raw materials for chemical and petrochemical industry.

Study on the kinetic characteristics of indoor air pollutants removal by ventilation

Ventilation is an efficient and convenient method to remove indoor air pollutants, such as particulate matter and VOCs. The computational fluid dynamics (CFD) method is an economical and efficient method to study the removal efficiency of indoor air pollutants by ventilation. However, CFD method is usually restricted by the extensive computational time. In this study, the kinetic characteristic of removing indoor air pollutants by ventilation was investigated to reduce the CFD computational time. The impact of ventilation rate and ventilation model on the removal efficiency of indoor air pollutants was studied. The results show that the removal of particulate matter and VOCs is consistent with the Langmuir–Hinshelwood (L-H) kinetic model when there are no barriers. The fit coefficients (R2) are larger than 0.984 and 0.978 under different ventilation rates and ventilation models, respectively. The fit coefficients of VOCs removal are larger than those of particulate matter. The removal of VOCs in a benchmark full-scale indoor model was successfully predicted by the L-H kinetic model with a mean prediction error of 0.8%. Meanwhile, 99% CFD computational times were reduced. The removal of particulate matter cannot be predicted accurately by the L-H kinetic model when the barriers present (prediction error reached 18.0%). Therefore, the L-H kinetic model is a high-efficient tool to design the ventilation rate and ventilation model when the main air pollutants are airflow-determined (gaseous pollutants or no barriers condition).

Formation of Dense and High-Aspect-Ratio Iron Oxide Nanowires by Water Vapor-Assisted Thermal Oxidation and Their Cr(VI) Adsorption Properties.

Coral-like and nanowire (NW) iron oxide nanostructures were produced at 700 and 800 °C, respectively, through thermal oxidation of iron foils in air- and water vapor-assisted conditions. Water vapor-assisted thermal oxidation at 800 °C for 2 h resulted in the formation of highly crystalline α-Fe2O3 NWs with good foil surface coverage, and we propose that their formation was due to a stress-driven surface diffusion mechanism. The Cr(VI) adsorption property of an aqueous solution on α-Fe2O3 NWs was also evaluated after a contact time of 90 min. The NWs had a removal efficiency of 97% in a 225 mg/L Cr(VI) solution (pH 2, 25 °C). The kinetic characteristic of the adsorption was fitted to a pseudo-second-order kinetic model, and isothermal studies indicated that the α-Fe2O3 NWs exhibited an adsorption capacity of 66.26 mg/g. We also investigated and postulated a mechanism of the Cr(VI) adsorption in an aqueous solution of α-Fe2O3 NWs.

Numerical visualization of drop and opening process for parachute-payload system adopting fluid\u2013solid coupling simulation

In order to study the fluid–solid coupling dynamic characteristics of parachute-payload system during drop process and analyze the unsteady aerodynamic characteristics under finite mass opening conditions, an adaptive moving fluid mesh method is developed on the basis of the existing arbitrary Lagrangian–Eulerian (ALE) fluid–solid coupling method. The calculation results of open force and drop velocity on the C-9 parachute demonstrate the effectiveness of this method. On this basis, the effect of canopies with three different permeability on parachute-payload system motion characteristic including opening property, steady descent property and stability is studied. Comparative analysis is conducted for structures and characteristics of vortex with different canopy materials, and interference mechanism of unsteady flow for parachute-payload system in unsteady oscillation is revealed. The results show that the adaptive moving fluid mesh method can effectively eliminate restrictions of existing simulation methods for parachute-payload system and significantly reduce calculation time. For the lightweight parachute, permeability has significant effect on kinetic characteristic of parachute-payload system. Canopy with large permeability has small opening load and structural stress in opening stage. After opening, there are mainly small vortexes distributed evenly behind the canopy with good stability. However, canopy with small permeability has obvious breath behavior and oscillation in opening stage. The main vortexes periodically shed off after opening. With the change of permeability from small to large, Parachute-payload system eventually presents three steady descent modes: conical descent, gliding descent and stable vertical descent.Graphical abstract

A High Selective Chemiluminescent Probe Derived fromIso‐luminol Enabling High Sensitive Determination of Ferrous Ions in the Environmental Waters

Main observation and conclusionA new chemiluminescence (CL) reagent named 4‐amino‐5‐thiocyanato‐phthalyl‐hydrazine (iso‐luminol‐SCN) is synthesized by the bromide‐mediated substitution reaction ofiso‐luminol with sodium thiocyanate in dimethyl formamide (DMF) at room temperature. Strong CL is observed foriso‐luminol‐SCN oxidized by hydrogen peroxide (H2O2) in the presence of Fe2+, with the CL intensity strongly depending on the concentration of Fe2+and being hardly interferred by other common metal ions. Based on this fact, a flow injection CL method is established for the high sensitive and selective determination of Fe2+. The CL intensity was linearly correlated with the concentration of Fe2+in the range of 1.0 × 10–8mol·L–1to 1.0 × 10–5mol·L–1following the equation CLnet= 166.3c+ 57.7 (c, ×10–6mol·L–1;n= 7;R2= 0.9988). The detection limit is calculated to be 3.2 × 10–9mol·L–1Fe2+based on the 3S0/K principle. The relative standard deviation (RSD) was 3.7% for 1.0 × 10–6mol·L–1Fe2+(n= 11), a support for the precision of Fe2+measurement. The recoveries of Fe2+were obtained in the range of 98.8%—101.6% in three real water samples, showing the applicability and reliability by the proposed method. The possible CL mechanism is proposed based on the kinetic characteristic of the CL reaction and the CL spectrum.

Autocatalytic Friedel‐Crafts Acylation of Arenes without Additional Catalyst and Additive

AbstractA new and autocatalytic method was developed for Friedel‐Crafts acylation of arenes without additional catalyst and additive. A series of electron‐rich arenes underwent the acylation to give the targeted product in low to high yields by using aryl, alkyl and vinyl acyl chlorides as the acylating reagent, which gave an effective method for the preparation of diaryl ketones, alkyl aryl ketones and α,β‐unsaturated ketones. Preliminary mechanistic investigation suggested that the present acylation displayed an induction period and a sigmoid kinetic profile characteristic of autocatalytic systems, and the resulting H+ played a role of the catalyst.

Математическое моделирование процесса гидроочистки дизельного топлива на основе кинетических характеристик его фракций

The principles of mathematical modeling of the diesel fuel hydrotreatment process as a multicomponent reaction system are considered. Feedstock containing a large number of organosulphuric components from the standpoint of increasing the level of model adequacy and calculation accuracy can be characterized by the total sulfur content in the raw material as a whole (1), the total sulfur content in pseudocomponents in the feedstock or its narrow fractions (2), the concentration of individual organosulphuric substances (3). It is shown that in cases 1 and 2, the concept of the reaction rate constant as a constant that characterizes the physico-chemical process is degenerate, and in calculations it should be considered as a kinetic characteristic that takes into account the inhomogeneity of the chemical process over time. As the hydrogenated feedstock comes into contact with the hydrogen-containing gas, the most active organosulfuric components with a high reaction rate constant are first hydrogenated on the catalyst, and at the final stage of the process, the less active components with a low reaction rate constant are hydrogenated. Examples of calculating the dependence of the kinetic characteristic and the total sulfur content in the hydrogenate in two broad fractions of diesel fuel on the time of contact of the reaction medium with the catalyst and the subsequent compounding of the fractions into diesel fuel.

The effect of torrefaction on the thermo‐kinetics of thermally processed black pine

AbstractThis paper investigates the kinetic behaviour of thermal decomposition of pre‐treated pine needles. The model‐free methods of Flynn‐Wall‐Ozawa (FWO), Kissinger‐Akahira‐Sunose (KAS), and Kissinger, are used to determine the kinetic parameters of the processed pine needles. For a comparative analysis, the kinetic characteristic of the pre‐treated pine needles is equated to the thermal decomposition of the raw pine needles. For torrefaction of the raw substrate, some changes related to the design have been made to the furnace. The raw material has been thermally pre‐treated at a temperature of 523 K for 5 minutes. The volumetric rate of nitrogen during the torrefaction process is 42 L · min−1, while the purge flow rate of nitrogen gas is 0.2 L · min−1 for the thermogravimetric analysis. The temperature range for the thermal degradation of the torrefied pine needles is 308 K‐873 K. The activation energies determined by the FWO and the KAS methods are 157.08 kJ · mol−1 and 160.54 kJ · mol−1, respectively, whereas it is 137 kJ · mol−1 by the Kissinger method. The activation energy computed by the FWO and the KAS schemes for the raw material is found to be 1.3% less than that of the processed pine needles. The aromaticity of the thermally processed pine needles is increased by 13.61%. Thermal immunity or stability due to the increasing fraction of lignin causes the activation energy and frequency factor of the pre‐treated pine needles to slightly elevate. The redistribution of the pyrolysis stages has been observed for the torrefied pine needle sample, the temperature scale at a constant heating rate increases slightly by 0.34% during the char formation.

Neutron and Neutron-Breeding Medium Interaction Process Description Within the Physical Birth-and-Death Model

Analytic methods for nuclear reactor physics problems are still of current interest. They allow the physical interpretation to be obtained for studied processes within simple mathematical apparatus. This work proposes a new approach of neutron and neutronbreeding medium interaction process description based on birth-and-death model. This approach was named the physical birth-and-death model. The equations for the main kinetic characteristic are presented and reactivity values are estimated for two subcritical nuclear assemblies: MASURCA and KUCA.