Decrease In Coefficient Research Articles

Numerical investigation of electroosmotic driven transport of MHD Casson fluid over an exponential stretching sheet using quartic B-spline method

The stretching surface flow phenomenon plays novel significance in the differential industrial sectors like manufacturing processes, food processing, polymers, petroleum engineering, glass fiber production, metal spinning, and many others. This research focuses on investigating the flow of electroosmotic-driven transport of magnetic Casson fluid over an exponential stretching sheet. The study employs mathematical modeling based on partial differential equations which are further truncated into ordinary system under the implementation of dimensionless variables. The quartic B-spline method is applied for obtaining solutions. Key findings indicate that electroosmotic and Helmholtz–Smoluchowski effects enhance fluid velocity, while magnetic forces reduce velocity. Additionally, an increase in the Hartmann parameter leads to a decrease in the skin friction coefficient.

Non-Invasive Hemodynamic Monitoring System Integrating Spectrometry, Photoplethysmography, and Arterial Pressure Measurement Capabilities.

Minimally invasive and non-invasive hemodynamic monitoring technologies have recently gained more attention, driven by technological advances and the inherent risk of complications in invasive techniques. In this article, an experimental non-invasive system is presented that effectively combines the capabilities of spectrometry, photoplethysmography (PPG), and arterial pressure measurement. Both time- and wavelength-resolved optical signals from the fingertip are measured under external pressure, which gradually increased above the level of systolic blood pressure. The optical channels measured at 434-731 nm divided into three groups separated by a group of channels with wavelengths approximately between 590 and 630 nm. This group of channels, labeled transition band, is characterized by abrupt changes resulting from a decrease in the absorption coefficient of whole blood. External pressure levels of maximum pulsation showed that shorter wavelengths (<590 nm) probe superficial low-pressure blood vessels, whereas longer wavelengths (>630 nm) probe high-pressure arteries. The results on perfusion indices and DC component level changes showed clear differences between the optical channels, further highlighting the importance of wavelength selection in optical hemodynamic monitoring systems. Altogether, the results demonstrated that the integrated system presented has the potential to extract new hemodynamic information simultaneously from macrocirculation tomicrocirculation.

Microscopic deformation and fragmentation energy consumption characteristics of soils with various moisture contents using discrete element method

Increased soil moisture content commonly leads to higher resistance and energy consumption during agricultural operations. However, the impact of moisture content on soil microscopic deformation and fragmentation energy consumption characteristics remains unclear. In this study, discrete element models of sandy clay loam with different gravimetric water contents (15.0%, 18.8%, 21.6%, 24.1%, and 27.3%) were constructed for simulation experiments using coupled contact method (Hertz-Mindlin with bonding and Hertz-Mindlin with JKR). The degree of soil fragmentation and the rate of crack propagation were investigated. The results indicated that at fixed gravimetric water content, fissure rate exhibited a pattern of slow increase, rapid increase, and eventual stabilization with increasing compression displacement, while the fissure transfer coefficient showed a pattern of first increase and then decrease. At a fixed compression displacement, the increase in moisture content led to a decrease in both fissure rate and fissure transfer coefficient. The analysis of soil stress-strain characteristics and energy dissipation patterns found that soil with a gravimetric water content of 27.3% (close to soil liquid limit) exhibited no compression yield point; at a soil gravimetric water content of 15.0%, the minimum crushing energy (Udmin) was achieved (1.32 J), with a maximum elastic strain energy (Uemax) of 1.83 J. Similarly, at a soil gravimetric water content of 24.1%, the minimum crushing energy (Udmin) was reached (2.17 J), with a maximum elastic strain energy (Uemax) of 2.25 J. The comparison between actual and simulated results revealed low relative errors (<6%) in Udmin for all the above soil gravimetric water contents, suggesting the feasibility of our coupled discrete element model for assessing soil crushing energy consumption. This study revealed microscopic deformation and instability fragmentation mechanisms of soils with various moisture contents under vertical axial loads. Our findings provide novel method and strategy for developing the high-efficiency low-consumption soil fragmentation model.

Hydrogen isotope permeation and retention behavior in the RAFM steel manufactured by laser powder bed fusion

Laser powder bed fusion (LPBF) has emerged as a promising additive manufacturing technique for producing complex components across various industries. This method is particularly instrumental in fabricating reduced activation ferritic/martensitic (RAFM) steel, a candidate structural material for the tritium breeding blanket. Hydrogen transport behaviors in the conventional RAFM steel have been largely investigated; however, they are not well understood in the LPBF-RAFM steel. In this work, we studied the hydrogen isotope permeation and retention behavior in the RAFM steel fabricated by LPBF, utilizing the deuterium gas driven permeation and thermal desorption spectroscopy experiments. The results show that the hydrogen isotope permeability of the LPBF-RAFM steel is close to the conventionally fabricated RAFM steel, but the diffusion coefficient is greatly lower and the retention is markedly higher in the LPBF-RAFM steel compared to the conventional RAFM steel. The large number density of microvoids and TiC precipitates in the LPBF-RAFM steel could be the predominant factors that result in the decrease in hydrogen isotope diffusion coefficient and the increase in the total amount of deuterium retention.

Formation of ceramic coating on VAL10 aluminum alloy surface via laser modification in polysilicate solution

This article presents the results of an experimental study on the physical and mechanical properties of the surface layer of the VAL10 aluminum alloy after pulsed laser treatment, conducted in a bath with an aqueous solution of polysilicates (PS) at various concentrations. Ceramic coatings were produced on specimens measuring 10×10×3 mm. The laser processing of aluminum alloy specimens was carried out using an Nd:YAG laser. The study demonstrates that the quality of the resulting surface and its properties can vary depending on the laser exposure parameters, the concentration of the polysilicate solution, and the overall processing technique. The scattering of radiation by the PS solution layer leads to a significant reduction in surface roughness. In specimens processed in ambient air, the crater sizes on the surface exceeded 400 μm, while for specimens processed in a PS solution, they did not exceed 100 μm. A comparative analysis of the impact of solution concentration on elemental composition was performed. The study also included an investigation of friction characteristics and the measurement of microhardness of the modified surface. The research revealed that surface hardening processes occur as a result of the treatment, associated with the filling of recesses with high-strength oxides. This enabled the creation of a mixture containing silicon carbide and aluminum oxide in the surface layer of the specimens. Furthermore, wear tests of the modified surface were conducted using a “ball–specimen” tribological coupling. Specimens subjected to laser irradiation in a PS solution demonstrated increased wear resistance (a 40 % reduction in wear) and a 30 % decrease in the friction coefficient. Additionally, an increase in microhardness was observed.

Analysis of Pressure Characteristics of Ultra-High Specific Energy Lithium Metal Battery for Flying Electric Vehicles

The lithium metal battery is likely to become the main power source for the future development of flying electric vehicles for its ultra-high theoretical specific capacity. In an attempt to study macroscopic battery performance and microscopic lithium deposition under different pressure conditions, we first conduct a pressure cycling test proving that amplifying the initial preload can delay the battery failure stage, and the scanning electron microscope (SEM) shows that the pressure is effective in improving the electrode’s surface structure. Secondly, we analyze how differing pressure conditions affect the topography of lithium deposits by coupling the nonlinear phase-field model with the force model. The results show that the gradual increase in the external pressure is accompanied by a drop in the length of the dendrite and the migration curvature in the diaphragm, and the deposition morphology is gradually geared towards smooth and thick development, which can significantly reduce the specific surface area of lithium dendrite. However, as cyclic charging and discharging continue, the decrease in the electrolyte diffusion coefficient results in higher internal stress inside the battery, and thus the external pressure must be increased so as to achieve marked inhibitory effects on the growth of the lithium dendrite.

Tribological and Mechanical Properties of Graphene Nano Platelets (GNP)-Reinforced Aluminium 7075 Nano Composites

Background:: The present need for manufacturing industries is the creation of a new class of engineered materials with high specific properties. In this regard, nanocomposite materials have shown promising results compared to monolithic materials. Recent patents also show high mechanical and tribological properties. Objective:: The tribological and mechanical properties of graphene nanoplatelets (GNP)-reinforced aluminium 7075 nanocomposites are reported in this article with the objective of finding optimum properties. Methods:: The nanocomposites were successfully produced with the stir casting technique, a liquid metallurgy route with varying weight percentages of reinforcement composition of 0.5%, 1%, and 2%. Results:: The result showed an improvement in ultimate tensile strength of 69.5% and microhardness of 76.67% in contrast to the base alloy when it was cast. The wear rate was dropped significantly by 43% and 40% in 10N and 20N loading conditions with respect to as-cast conditions. Further, a decrease in the average coefficient of friction was observed from 0.680 to 0.565. Conclusion:: Graphene nanoplatelets came out as excellent reinforcement in the aluminium 7075 alloy, as they showed an impact on improved properties. The decreasing wear rate and coefficient of friction showed their self-lubricating nature. Additionally, X-ray diffraction (XRD) results and optical microstructure were also discussed.

Investigation of static and rotordynamic characteristics of the segmented annular seals based on the differential quadrature method

Theoretically, a solution model for the static and rotordynamic characteristics of a segmented annular seal based on the local differential quadrature (LDQ) method was established. The impacts of node density and the number of local support domain nodes on the accuracy of the algorithm were analyzed. A test rig for the leakage of segmented annular seals was designed and built. The leakage results measured on the test rig were compared with the theoretical analysis results to demonstrate the accuracy of the local differential quadrature method. The influence of structural and operating parameters on the seal static and rotordynamic characteristics was analyzed Based on the work carried out above. The research results indicate that when the number of local support domain nodes is equal to 3, the static and rotordynamic characteristics of the segmented annular seal can be obtained accurately based on the solution model. As the rotational speed increases, the segmented annular seal’s lift force, leakage, stiffness coefficient, and damping coefficient increase. As the pressure ratio increases, the lift force and leakage of the segmented annular seal significantly increase while the stiffness and damping coefficients decrease. As the depth and width of the pocket increase, the lift force, stiffness coefficient, and damping coefficient of the segmented annular seal first increase and then decrease. As the length of the pocket increases, the lift force, stiffness coefficient, and damping coefficient of the segmented annular seal increase. The influence of the pocket depth, width, and length on the leakage is minimal.

Parameterization scheme of the sea surface drag coefficient considering the influence of wave states and sea spray stress

The drag coefficient of the sea surface is crucial for the exchange of momentum between the ocean and atmosphere. The wave state significantly influences the variability of the drag coefficient. In the past, researchers commonly employed single-parameterization methods to describe this influence. However, the influence of wave conditions on drag coefficient is complex and variable, and it is difficult to accurately describe it with a single parameter alone. Wave age represents the ability of wind-induced waves to input energy, while wave steepness reflects the stability of the waves. By simultaneously considering wave age and wave steepness, a more accurate characterization of the dynamic nature of waves can be achieved. Additionally, the presence of sea spray profoundly impacts the distribution of the momentum flux between the ocean and atmosphere, thereby influencing the drag coefficient of the sea surface. In this study, we established a novel sea spray generation function that bases on both the wind speed and wave states (wave steepness and wave age). Considering this function, the momentum flux of sea spray droplets was analyzed under different wave states. Moreover, with increasing wave age or wave steepness, the effective sea surface drag coefficient is attenuated at low to moderate wind speeds. Considering the challenge of simultaneously obtaining wave age and wave steepness data, this paper proposes a relationship equation between the two wave state parameters. When the wave age is greater than 0.4, the correlation between the wave age and the wave steepness is strong. As the wind speed increases from low to high, there is a noticeable decrease in the effective sea surface drag coefficient with the corresponding increase in wave age. When the wave age is less than 0.4, the wave steepness reaches a maximum value, and the effective sea surface drag coefficient increases with the increase of the wave age at medium and low wind speed. With further increases in wind speed, the momentum flux derived from the air also increases. Simultaneously, the effective sea surface drag coefficient exhibits a decrease as wave age increases.

Titanium carbide (TiC) dispersed surface on titanium based alloy (Ti-13Nb-13Zr) by in-situ laser composite surfacing and its wear performance

Ti-13Nb-13Zr is a promising titanium-based alloy for bioimplant applications due to its low Young’s modulus (80 GPa). However, it undergoes mechanical and mechano-chemical degradation after long-term application in the human body. The present study concerns the development of TiC dispersed surface on Ti-13Nb-13Zr by preplacement of graphite and subsequent melting with a continuous wave (CW) fiber-coupled diode laser using varied power (1000 W to 1400 W) and scan speed (10 mm/s to 20 mm/s). Laser composite surfacing leads to the formation of dispersion of carbide (TiC) in the beta (β) matrix. There is an improvement in microhardness from 257 VHN (for as-received) to 360–519 VHN for laser composite surfaced Ti-13Nb-13Zr and varied with process parameters. There is an increase in nanohardness value from 3.6 GPa (for as-received Ti-13Nb-13Zr) to 5.14–9.224 GPa and increased in Young’s modulus from 100 MPa (for as-received Ti-13Nb-13Zr) to 103.22–120.85 MPa due to laser composite surfacing. A significant improvement in wear resistance (5.8 times) and a decrease in coefficient of friction (COF) (2.8 times) against the WC ball in fretting wear mode was noticed. The wear mechanism has been schematically presented and discussed in details.

Research on the effect of shallow draft on the performance of azimuth thruster under bollard conditions

For the azimuth thruster installed on shallow draft ships, the shallow water effect leads to a decrease in propulsive performance, especially under the bollard condition. In order to accurately predict the bollard propulsion performance of the azimuth thruster under shallow draft conditions, this paper firstly obtains the bollard thrust performance in several waters through the shallow water test, and then analyzes the effect of hull wake and cavitation on the bollard thrust performance of the azimuth thruster by using the CFD method. The results are consistent with the test results under the open water. When the water depth is less than 1.0D, the thrust coefficient increases with the increase of water depth, when the water depth is greater than 1.0D, the thrust coefficient basically does not change; Considering the influence of hull wake, the axial inlet velocity of the azimuth thruster is 7.27% higher than that of the open water condition; meanwhile considering the influence of the hull wake and cavitation, the leading edge of the bottom of the azimuth thruster conduit and the back of the paddle blade are susceptible to cavitation, which leads to average decrease of the thrust coefficient and torque coefficient by 7.03% and 6.12%, respectively.

Downhole detection of gas kick using low-frequency elastic wave: Multiphysics modeling and its implications

Gas kick is a common and high-risk drilling trouble in geo-energy engineering, especially for deep-water drilling and ultra-deep well drilling. The most favorable way of early detection of gas kick is to move the detection from the wellhead or near surface to the downhole. In this paper, a new conception of downhole detection of gas kick using low-frequency elastic wave was put forward. The framework of coupling the multiple physic processes of gas-liquid two-phase annulus flow, bubble migration and low-frequency elastic wave propagation during gas kick was developed. The characteristic responses of low frequency elastic wave to gas kick were quantitatively analyzed based on multiphysics modeling under the ideal case and different levels of background gas (BGG), respectively. The modeling results indicated that: (i) The velocity decreases cliff-like and the attenuation coefficient increases significantly at the gas-kick bubble front. The change magnitudes of the velocity and the attenuation coefficient increase with the gas intrusion rate, and decrease with the pump displacement. The change magnitude of attenuation coefficient decreases with mud density, while the increase of velocity is not sensitive to the mud density. (ii) For the ideal case of the vertical well, the effective detection within the depth section of (2014–2568) meter could identify gas kick about (14.3–29.2) minutes earlier than the conventional pit-gain method. The gas kick could be identified earlier when the deviation angle is smaller and/or the monitoring point goes deeper. (iii) The changing magnitudes and rates of the velocity and the attenuation coefficient decrease with the BGG. The downhole detection of gas kick using low-frequency elastic wave should be reliable when the BGG is lower than 5%. The effects of rock cuttings, phase transition of the gas, and drill-string vibrations should be further investigated in future study.

Оптическая плотность и атомные отношения Н/С гумусовых кислот донных отложений озер Среднего Приобья

The paper presents the results of studies of the optical density of alkaline solutions of humic acids (HA) and himatomelanic acids (MMC) characteristic of the Middle Ob bottom sediments of lakes of silicate, organo-silicate and organic class and their dependence on the atomic ratios of H/S of HA macromolecules. It is established that the results of spectroscopy of the UV and visible regions of the HA spectrum depend on the results of the elemental composition. With an increase in the atomic ratios of N/S, the values of E465 quantities (quasi-extinction coefficients) decrease, which reflects the composition of the aromatic part of GC macromolecules. MMCs have been studied, however, they contain more peripheral groups than GC and do not have patterns of the relationship of E465 quantities from N/S, therefore, correlation dependencies are not given in the article. The highest content of aromatic carbon in GC was found for samples of GC K-6 of the silicate class of the Kondinsky province (left bank of the Ob) and C-5 of the organic class of the Sredneob province (right bank of the Ob). The general correlation dependence of N/S and E465 values is higher in the samples of the GK of the Kondinsky province. Keywords: SAPROPEL, HUMIC ACIDS, HIMATOMELANIC ACIDS, UV SPECTROSCOPY, MIDDLE OB

Nucleation and growth mechanism of Ni/SiC composite coatings electrodeposited with micro- and nano-SiC particles

To study the nucleation and growth mechanism of Ni/SiC composite coatings, electrodeposition was conducted in the Ni bath containing SiC particles with different sizes. Compared to the Ni coating electrodeposited from the bare Ni bath, the Ni/SiC composite coatings exhibited similar grain size but rougher surface morphology due to the incorporation of SiC particles. By means of chronoamperometry (CA) and linear sweep voltammetry (LSV) techniques, it was found that the introduction of SiC particles did not change the nucleation mode of Ni: the Scharifker-Hills three-dimensional instantaneous nucleation mode. However, the nucleation sites on the cathode were reduced due to the inert surface and low conductivity of SiC particles. At a step potential of −0.94 V, Ni presented the maximum nucleation density (N0) of 3.09 × 107 cm−2, which was reduced by one order of magnitude for the Ni/SiC. Furthermore, SiC particles in the bath would extend the diffusion path of Ni2+ ions, resulting in the decrease in diffusion coefficient from 1.04 × 10−7 cm2 s−1 (Ni) to 9.91 × 10−9 cm2 s−1 (Ni/50 nm SiC), 1.83 × 10−8 cm2 s−1 (Ni/500 nm SiC) and 2.29 × 10−8 cm2 s−1 (Ni/5 μm SiC), suggesting the “Blocking effect”. COMSOL simulation further confirmed the “Blocking effect”. The “Blocking effect” would lead to excessive interface gaps around 5 μm SiC particles due to the uneven electrodeposition of Ni. To address the issue, we proposed that adding non-ionic surfactants into the bath to lower the electrochemical reaction rate of Ni2+ ions and accordingly gained composite coatings with fine continuity.

Study of the effect of onion husk ethanol extract on the chemical composition and microstructure of meat pates

The wide use of antioxidants is due to their involvement in free radical processes in foods and human body. Interest in the use of low-value raw materials providing products with functional properties and increasing their shelf life is rapidly increasing. However, any changes in the formulation and technology may affect the properties and composition of the finished product. During the work, the effect of replacing 34% (sample 1) or 17% (sample 2) beef broth with 70% water-ethanol extract of yellow onion peels in the formulation of the experimental meat pates was investigated. The control product contained only beef broth as liquid. The total antioxidant capacity by the DPPH radical method (TACDPPH), fatty acid composition and amino acid composition were determined; microelement content analysis, proteomic and microstructural studies of meat pate samples with and without the addition of extract were also carried out. For 14 days, TACDPPH values of experimental pates were higher than in control by at least 2.32 times (P&lt;0.10). Samples 1 and 2 were characterized by a decrease in the concentrations of zinc, manganese and magnesium by no more than 14% (P&lt;0.10), with a simultaneous increase in selenium, copper, potassium and calcium of 8% to 17.35% (P&lt;0.10) depending on the microelement. The mass fraction of protein in experimental pates 1 and 2 was higher by 6.76% and 2.73% (P&lt;0.10), respectively, which was due to a decrease in moisture because of ethanol evaporation. Replacing the broth in the formulation affected the decrease in the protein biological value, as evidenced by a decrease in amino acid scores (AASs). However, a decrease in the AAS difference coefficient in experimental pates 1 and 2 by 7.71% and 3.07%, respectively, led to an increase in the biological value of the pates by 7.7% and 3.06%, respectively. Based on the results of proteomic and histological analysis, it was revealed that the addition of ethanol extract did not lead to significant changes in the protein composition and microstructural characteristics of the test samples.

Simulation study of water shut-off treatment for heterogeneous layered oil reservoirs

The purpose of this paper is to develop a hydrodynamic model of two-phase, three-component fluid flow in a heterogeneous layered reservoir, taking into account cross-flow between layers, and to predict the process of oil displacement by water under conditions of water shut-off in the vicinity of injection or production wells. Numerical calculations at different water cuts (38%, 50%, 96%) showed that in the presence of cross-flow between layers, the current oil recovery coefficient of the reservoir at water shut-off in the vicinity of the producing well increases by 0.3254, 0.3067, and 0.0429 respectively, compared to water shut-off in the vicinity of the injection well. In the absence of cross-flow between layers, there is a decrease in oil recovery coefficient by 0.0082 and 0.0072 at 38 and 50% water cut, respectively. Additionally, there is an increase in recovery coefficient by 0.007 at 96% water cut. It was also obtained that in the presence of cross-flow between layers the gel washout period at water shut-off in the vicinity of the injection well is less at different water cut in 1.24–1.81 times than in the vicinity of the production well. In the absence of cross-flow between layers, the washout time at 38 and 50% water cut is almost the same, but increases by 1.084 times at 96% water cut. Comparison of results of water shut-off prediction using proposed hydrodynamic model and real data showed that calculations describe real data with an average error of about 7%.

Experimental study on scale inhibition performance and fouling characteristics of spiral insert in heat transfer tube

In order to study the anti-scaling and descaling performance in the process of cooling crystallization, the effects of flow velocity and reciprocating displacement on fouling resistance and overall heat transfer coefficient under two spiral insert schemes are experimentally studied. The system studied in the experiment is a saturated sodium sulfate solution, which forms crystalline fouling during the experiment. The micro structure of the fouling layer is investigated to explain the variation of macroscopic thermal parameters. The average fouling thickness curve is obtained by heat transfer theory analysis. The results show that the maximum decrease of the asymptotic value of the fouling resistance of the fixed spiral insert is 63 % with the increase of the flow velocity. When the reciprocating displacement of the spiral insert increases to one pitch, the asymptotic value of the fouling resistance decreases by 83 %, and the overall heat transfer coefficient decreases by only 3 %. The particle size and porosity of fouling at different observation positions gradually increased, while the shape of fouling crystals changed from small to regular, and the degree of bonding changed from tight to loose. Statistics on the particle size of fouling particles show that the fouling particle size increases from 2-8 μm to more than 30 μm. For the fixed spiral inserts, the porosity of the fouling layer is up to 42 %, but the porosity of the middle layer increases rapidly with the flow velocity. With the change of flow velocity, the flow field characteristics in the tube are the main reason for changing the structure of the fouling layer. With the increase of reciprocating displacement, the collision effect of the spiral on the fouling layer is more comprehensive, and the interlayer bonding of the fouling layer is completely destroyed. In the field of industrial cooling crystallization, it can greatly improve the heat transfer efficiency of the inner wall crystallization process.

Numerical Simulation of Time-Varying Characteristics in a High-Permeability Sandstone Reservoir: A Case of Gaoqian Southern Area

In the process of long-term water flooding in the Gaoqian Southern Area with an average porosity of 30% and an average permeability of 1333.5×10−3 μm2, the fluid-solid interaction among oil, water, and rock has a great influence on the pore structure. It has resulted in changes in reservoir parameters with the extension of time. This paper used electron microscopy scanning, mercury injection, X-ray diffraction, physical properties, and oil-water relative permeability curves to study the variation of clay mineral content, pore throat structure, porosity, permeability, and relative permeability curves of high-permeability sandstone after high-pressure water flooding. The results showed that clay minerals such as montmorillonite and kaolinite were dissolved, hydrated, and migrated after long-term water flooding, which resulted in the decrease of clay mineral content in fine sandstone and medium sandstone, the increase of pore throat radius, and the decrease of displacement pressure, median pressure, and separation coefficient. The saturation of the isotonic point of the oil-water relative permeability curve was obviously shifted to the right, the hydrophilicity was significantly enhanced, and the porosity and permeability were effectively improved, but there was a blockage of the throat less than 2 μm in the fine sandstone. In addition, this paper established the equations of water injection, permeability, irreducible water saturation, residual oil saturation, and oil-water relative permeability curve coefficient and establishes the initial permeability model with the well data before water flooding. The logging interpretation results of development wells in the process of water flooding as verification data were used, and the relative error of permeability far lower than the general requirement of permeability error within an order of magnitude was less than 30%, which verified the rationality of the method.

Electrochemical Behavior of Niobium and Titanium Complexes in Chloride-Fluoride Melts with Addition of Alkaline Earth Metal Cations

The standard rate constants of charge transfer (k s) for the Nb(V)/Nb(IV) redox couple in the NaCl-KCl(equimol.)-NaF(10 wt%)-K2NbF7 melt with addition of alkaline Earth metal cations (Mg2+, Ca2+, Sr2+, Ba2+) were determined. It was found that addition of alkaline Earth metal cations resulted in increasing of k s to the certain ratio of Me2+/Nb(V) for the all alkaline Earth metal cations due to substitution of Na+ and K+ cations by Me2+ in the second coordination sphere of niobium complexes that leads to decreasing of niobium fluoride complexes stability. Further addition brought to some decrease of the standard rate constants because the viscosity of melts increasing, which brings to decrease of the diffusion coefficients. The standard rate constants increase with increasing of the ionic potential and reach maximum values for the complexes with outer-sphere magnesium cations. Comparative analysis of the electrochemical behavior of Nb(V)/Nb(IV) and Ti(IV/Ti(III)) redox couples in the NaCl-KCl(equimol.)-NaF(10 wt%) melt without and with addition of alkaline Earth metal cations has been done. It was determined that mechanism of electron transfer from the cathode to niobium and titanium complexes in melts containing alkaline Earth metal cations is the same and has a bridge nature.

Imperfect Vaccination Evolutionary Game Incorporating Individual Social Difference and Subjective Perception

Previous studies have focused on the assumption that individual attitudes toward epidemics, epidemic-related information, and vaccination are identical with much less effort attempting to consider psychological factors and individual heterogeneity. In this article, we employ a two-layer susceptible–infected–recovered–vaccinated/unaware–aware–unaware (SIRV-UAU) coupled network to depict the interplay between epidemic spreading and information diffusion. We propose an imperfect vaccination evolutionary game model integrating prospect theory (PT) to explore the effect of individual subjective perception and social difference on epidemic spreading and vaccination equilibrium. We find that the individual social difference in the epidemic spreading layer has a more significant impact on the epidemic threshold than that in the information diffusion layer. Individual psychological perception and vaccination behavior decision-making determine the vaccination equilibrium: under the PT, vaccination equilibrium increases with the decrease of the rationality coefficient when the vaccination cost is small. Furthermore, we analyze the effect of social differences on individual vaccination behavior decision-making and find that vaccination equilibrium increases with the increase of social reinforcement strength and primary protective probability. Finally, we discuss the effect of infection cost on vaccination equilibrium when the infection cost of vaccinated individuals is less than that of unvaccinated individuals and observe that a small infection cost helps improve the vaccination equilibrium.