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Biogas, landfill gas, associated petroleum gas, and other tail gases accompanying various industrial processes are potential sources of hydrogen and carbon monoxide for solid oxide fuel cells via the reforming process. As these gases contain heavy hydrocarbons, fine-tuning of steam and carbon dioxide addition and specific temperature control are necessary to avoid carbon deposition during the reforming process. Numerical simulation plays a crucial role in designing miniaturized steam reforming reactors and optimal working conditions. All simulations of reforming processes must account for carbon deposition. The methods commonly seen in the open literature include Gibbs free energy minimization or parametric equations formalism. This paper utilizes Gaussian process regression as a tool for making predictions about which reforming parameters are suitable for carrying out this process without the danger of damaging the catalyst due to a carbon formation. Parametric equations formalism and Gibbs free energy minimization involve either the minimization of objective function or a search for roots of nonlinear functions. These tasks are sensitive to a choice of the starting points of the algorithm — wrong choice of starting points could lead to numerical instability. Unlike conventional methods, the Gaussian process regression approach bypasses the computation of equilibrium composition. It predicts carbon formation tendencies directly from the initial conditions which ensure stability.

A numerical investigation of transient, two-dimensional natural convection in horizontal isothermal cylindrical annuli is performed to investigate the Prandtl number and diameter ratio effect on flow and heat transfer characteristics. The finite difference method is used to solve the governing equations, in which buoyancy is modeled via the Boussinesq approximation. Both vorticity and energy equations are solved using alternating direction implicit (ADI) method and stream function equation by successive over relaxation (SOR) method. Solutions for laminar case are obtained up to Grashof number of 105 as well as three different diameter ratios, namely 1.2, 1.5, and 2.0 and the Prandtl number varies from 0.7 to 10 are considered. The computed flow patterns and temperature fields are shown by means of streamlines and isotherms, respectively, and the average heat transfer coefficients are also presented. The numerical results are summarized by Nusselt number vs. Grashof number correlations with the Prandtl number and diameter ratio as a parameter. The results of the parametric study show that the diameter ratio and Grashof number have a profound influence on the temperature and flow field and they are almost independent of a low Prandtl number fluid. The average Nusselt number increases by 25% at large of diameter ratio and Prandtl number. Good agreement with earlier available data is obtained.

This research including a study of mechanical ,physical properties (band structure, density of states) and the elasticity constants of the Barium Ortho titanate by using Materials studio software. The calculations were based on the generalized gradient approximation (GGA) by linear method. The calculated equilibrium lattice constants of monoclinic barium orthotitanate were: a = 0.612nm, b = 0.77nm, c = 1.05nm,calculated bulk modulus =42.3021 GPa, young modulus= 40.29 GPa, share modulus = 15.97 GPa, lame constant (λ)= 142.56 GPa ,and energy band gap=3.435eV which is indirect band gap and the composite is insulator and the electronic properties where be calculated in first Brillion zone. According the mechanical stability conditions the composite is stable mechanically. These results were calculated by Materials studio software.

In this paper, an enhanced thermal model is proposed for pouch batteries, which can be used for a battery management system (BMS) at low temperatures and high current rates. This thermal model integrates a virtual resistance model (VRM) and post resistance model at low temperatures. Firstly, based on the Arrhenius equation, the resistance model at low temperatures (from 0 °C to -10 °C) and high discharge rates (from 3.125C to 12.5C) is extrapolated from the resistance model under room temperature conditions. In this context, the resistance model at low temperatures is regarded as the VRM. In comparison to the experimental results, the maximum error of this VRM is 0.851 mΩ. Additionally, the equivalent post resistance model of the pouch battery, including that of the positive electrode and negative electrode, is also given for low temperatures. Finally, the complete thermal model for pouch batteries is validated at low temperatures and high discharge rates. The temperature evolution at different points on the battery, along with the heat generation properties of the battery, are simulated under cyclic pulse current and constant current working conditions. For cyclic pulse current, the maximum mean error in terms of temperature evolution is 0.72 °C, and for constant current working conditions, the maximum mean error is 0.79 °C.

In this research, experimental investigation of the coefficient of the heat transfer has been conducted for a set of rectangular fins with different fin height, 0.27, 0.47 and 0.67 m at air velocity test points of 1.1, 1.3, 1.5, 1.7 and 2 m/s, to meet the Reynolds number (Re). Thirty samples from the two cases with changing fin positions were studied to verify the thermal performance of the system. The study was conducted based on the cross-sectional diameter of 21167, 25016, 28864, 32713, and 38486. Total heat flux in all tubes has been settled as 26.3, 58, and 88.7 W/m2. The experimental results showed that the temperature difference between the surface of the block and flowing air increases with increasing Reynolds number for all heat flow states.

Objective: A numerical and theoretical study is developed to analyze the combined effect of activation energy and chemical reaction in the flow of nanofluids due to the thin moving needle using the mathematical nanofluid model offered by Buongiorno. A passively controlled nanoparticle volume fraction boundary is assumed rather than actively controlled. Methods: A similarity transformation is utilized to convert the governing partial differential equations to a set of ordinary differential equations which are then solved numerically by Runge-Kutta Shooting Method (RKSM). The physical characteristics of flow, heat and mass transfer are illustrated via graphs and tables for some set of values of governing parameters. Results: In addition, the basic non-linear governing equations are solved analytically using semianalytical technique called Differential transform method (DTM) and the comparison has been made with the numerical and the published results. Conclusion: The present study reveals that the ratio between the needle velocity and the composite velocity brings out to increases the velocity distribution with λ

The prosthetic socket base material must have exhibited good mechanical properties. An experimental investigation about the behavior of different fibers reinforced laminated composite materials were done. This work has been done on seven laminated composites which were prepared by the Vacuum bagging technique from Polyester resin as a bonding matrix and reinforced with (Jute, Glass, Carbon, Perlon) fibers. Laminated specimens were characterized by mechanical tensile tests such as (Tensile Strength, Young’s Modulus, Elongation Percentage) and physical test (density) to measure specific strength and specific modulus. SEM test also had been studied for different laminated composite. The results of experimental work showed that the mechanical properties were changed with the type and number of reinforcing layers. So, the results showed that the best laminated composite specimens have three layers of Jute with four layers of Carbon fiber. Where tensile strength and modulus of elasticity reach (162 MPa. and 3.60 GPa.) respectively. And specific strength and specific modulus reach to (134 MPa.cm3/gm–2.544 GPa.cm3/gm). The smoothness of the fractured surface will increase, indicating a brittle to semi-ductile transformation, according to SEM results.

s Flower-like BiOI and Bi5O7I photocatalysts were synthesized by a microwave-assisted solvothermal process and then calcined at various temperatures. The effects of calcination temperature on the phase structure, crystal property, morphology, color, optical property, and activity of the photocatalysts were investigated. As the calcination temperature increased, a blue shift was observed in the diffuse reflection spectra and the band gap increased. After the calcination treatment at 500 °C, the XRD, Raman spectra, and TEM results confirmed that BiOI transformed to Bi5O7I. Although flower-like microspheres still existed, the shapes of building blocks changed from lamellar nanoplates to thick twisted stripes when the BiOI transformed to Bi5O7I. BiOI with a calcination treatment at 300 °C exhibits an improved H2 production activity of 1373 μmol g−1 h−1. The XRD spectra reveal that the B-400 photocatalyst was a Bi5O7I-rich and BiOI-deficient composite material. Fewer Bi5O7I–BiOI interfaces and lower light absorption may be the reasons why the B-400 photocatalyst with Bi5O7I–BiOI compositions did not exhibit higher activity than B-300 (pure BiOI) and B-500 (pure Bi5O7I) photocatalysts.

Bulk La2O3-Ga2O3-ZrO2 (LGZ) glass and Tm3+/Yb3+ co-doped LGZ glasses were synthesized successfully using containerless technique. Raman spectra result reveals that the matrix sample possesses the low highest phonon energy of ∼ 642 cm–1. The glasses show good compatibility between large Abbe numbers (>31) and high refractive indices (nd > 1.93). Moreover, transmittance measurements reflect the glasses have high infrared transmittance of ∼ 81.9%, small OH– absorption coefficient and long mid-infrared cut-off wavelengths (∼7.5 μm). The surface morphology of host glass was characterized by SEM micrograph and EDS tests reflect that the doped compositions are distributed into the matrix glass homogeneously. The results of thermal analysis show that the glasses have good thermal properties (Tg > 769 °C). Excited by 980 nm laser, an intense 1810 nm fluorescence is obtained originating from the transition: 3F4 → 3H6 of Tm3+ ion, accompanied by upconversion emission. It can be observed that 1810 nm fluorescence has the highest intensity at 1 mol% Yb2O3 and owns broad full width at half-maximum (>245 nm), the luminescence intensity of 3F4 → 3H6 transition increases with rising temperature from 300 to 550 K. Furthermore, the value of energy transfer efficiency shows that Yb3+ can transfer energy to Tm3+ effectively. By fitting the attenuation curves, the lifetimes of 1810 and 474 nm emission can be acquired.

Inexpensive Cu2ZnZnS4 (CZTS) films using a two-step method have been developed for use in photovoltaic devices. Gavalnostatic electroplating precursors from environmentally friendly electrolytes and sulfurization were implemented in this method. Optimized sequential electrodepositions of Cu, Sn, and Zn films were carried out on molybdenum-coated glass, while the sulfurization of Mo/Cu/Sn/Zn precursors was performed at 500 °C or 550 °C in a sealed quartz tube filled with argon. The produced CZTS films were characterized in detail by photoelectrochemical measurements (PECMs, as photoelectrocatalytic detections), scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDX), Raman microspectroscopy, X-ray diffraction (XRD), and UV-Vis spectroscopy. PECMs revealed a photocurrent of “copper poor” CZTS sulfurized at 550 °C up to 1.5 mA/cm2, much higher than that of “copper rich” CZTS sulfurized at 550 °C (0.1 mA/cm2). SEM showed Sn particles were dispersed in the precursors, and the morphologies of “copper poor” CZTS showed less crevices and/or pinholes than those of “copper rich” CZTS. EDX analysis showed only Zn-loss could be found after the sulfurization. Raman imaging revealed the uniform composition of “copper poor” CZTS sulfurized at 550 °C, while “copper rich” CZTS processed at the same temperature contained binary compound SnS2 interposing the CZTS. The results of both XRD and Raman depicted that all CZTS films possessed kesterite structure. A direct band gap of about 1.45 eV for the produced CZTS film was determined from UV-Vis spectroscopy. All the measurements demonstrated that the CZTS film fabricated by galvanostatic electroplating meets the requirements for a light-absorbing layer and is a potential candidate for assembling CZTS solar cells. The J-V measurement of the resulting device confirms this assertion, and demonstrates a 5.0% conversion efficiency of the CZTS solar cell.

Oxygen-assisted high temperature solid-state reaction approach was employed for the fabrication of Pr activated Ba(Mg0.28Zr0.16Ta0.56)O3 transparent ceramic phosphor. Retiveld refinement of X-ray diffraction pattern was carried out to reveal the lattice parameters and crystal structural information. Under the blue-light excitation of λex=473 nm, the phosphor exhibits a sharp intense red emission centered at 645 nm, accompanied by serval other weak peaks. PL evolution with temperature shows a significant luminescence quenching behavior, and the underlying multi-phonon interaction with optical center is revealed by proposing an unprecedent theoretical calculation work. Such a phonon effect is further confirmed from the red-shift of peak position with temperature, and the involved phonon energy of 50.7 meV is determined from Raman scattering measurement. More interestingly, the fitted results of transient-state PL spectra show a fluctuation of luminescence lifetime at various temperatures, further indicating a significant effect of phonon vibration in the system.

Ionic liquids (ILs) have attracted increasing attention since last few decades due to their high molecular design abilities and wide applications in different fields. In this study, four novel fluorescent isoquinolino [2,1-a]quinoxalin-5-ium ILs were designed and synthesized via a two-step process including a simple dual Schiff's base formation and a subsequent [RhCp∗Cl2]2-catalyzed oxidative C–H activation/annulation reaction. The as-synthesized ILs were extensively characterized using FT-IR, 1H-NMR, 13C-NMR, 19F-NMR, HSQC-NMR, HMBC-NMR and HR-MS. Their photophysical properties were determined by steady-state fluorescence spectroscopy. The results demonstrate that all these ILs showed dual or triple emissions, large stokes shift (90 nm) and mechanochromic behaviors. Basing on solvatochromism and titration experiments, it is thought that the emission bands of the ILs are raised from their local excited states, charge transfer states or excited state proton transfer of cations, while the substitute effect of these quinoxaline derived ILs on their stokes shifts is negligible.

Magnetic nanoparticles (MNPs) have been widely studied for use in biomedical and industrial applications. The frequency dependence of the magnetization of magnetic nanoparticles is analyzed for different AC excitation fields. We employ a Fokker-Planck equation, which accurately describes AC magnetization dynamics and analyze the difference in AC susceptibility between Fokker-Planck equation and Debye model. Based on these results we proposed a simple, empirical AC susceptibility model. Simulation and experimental results showed that the proposed empirical model accurately describes AC susceptibility, and the AC susceptibility constructed with the proposed empirical equation based on Debye model agrees well with the measured results. Therefore, we can utilize the proposed empirical model in biomedical applications, such as the estimation of the hydrodynamic size and temperature, which is expected to apply to biologicals assays and hyperthermia.

Wear debris sensing is an important approach for machine condition monitoring. To date, different types of debris sensors have been developed, among which the magnetostatic inductive debris sensor is preferable for monitoring ferromagnetic debris, but the existing induced voltage model cannot be used to quantify wear debris in lube oil. Accordingly, a modeling method was proposed for the debris sensor based on a high-gradient magnetostatic field. First, a Gaussian curve is used to fit the magnetic field along the axis of the sensor. Then, time-harmonic electromagnetic field analysis and Fourier series decomposition are combined to establish an induced voltage model. Furthermore, the influence of the relative permeability, size, and velocity of wear debris and induction coil parameters on the output voltage is analyzed. The results show a linear relationship between the theoretical calculations and experimental results. Therefore, the proposed model can be used to realize quantitative analysis of wear debris, laying a foundation for optimizing the sensor structure, and extracting features from output voltage signals.

Chromic oxide (Cr2O3) monolayer is a promising alternative hydrogen evolution reaction (HER) catalyst compared with expensive platinum (Pt) due to its advantages such as low cost, large specific surface area, high reserves, and designability. In this study, the two practical strategies, strain engineering and transition metal (TM) doping (Mn, Fe, Zn, etc.), are proposed to activate the catalytic sites of Cr2O3 monolayer for the HER. The density functional theory (DFT) calculations demonstrate that the strained Cr2O3 monolayer can stimulate the HER activity with the Gibbs free energy of hydrogen adsorption (ΔGH∗) close to 0.09eV, which can be considered as a performable strategy to tune the HER catalytic behavior of Cr2O3 monolayer. For the TM doping, it also plays a role in the performance adjustment. These results provide a guideline to optimize the HER performance of Cr2O3 monolayer.

The present work aimed to investigate the electrochemical properties of ITO substrates in propylene carbonate (PC) with 0.5 mol/L lithium perchlorate (LiClO4) medium in the presence of elaborated thin films of cerium dioxide pure and doped with manganese at varying percentages Ce1–xMnxO2 (x=0 wt%, 2 wt%, 4 wt% and 6 wt%) were successfully deposited by the spray pyrolysis (SP) technique on the glass substrate and ITO at 450 °C.The effects of manganese (Mn) doping thin films Ce1–xMnxO2 were studied and investigated by using different analyses namely X-ray diffraction (XRD) analysis, Raman spectroscopy method, UV-Vis spectrophotometer technique, atomic force microscopy (AFM) analysis and electrochemical properties. XRD data obtained present a polycrystalline with a face-centred cubic structure of fluorite type. Raman results of thin films undoped and Mn doped show two peaks at 465 and 600 cm–1, this letter due to the formation of extrinsic oxygen vacancies by the incorporation of Mn rate into Ce1–xMnxO2 matrix. Energy dispersive spectroscopy (EDS) data show the presence of Ce, O, and Mn elements in the elaborated films. The AFM results reveal that the surface roughness decreases with increasing Mn rate. Further, band gap energy of thin films decreases with increasing in Mn rate due to the formation of defect state between valence and conduction band. The storage capacity of the elaborated (Ce1–xMnxO2/ITO/PC+LiClO4) electrode reaches a maximum of 1.997 mF in the presence of 6% of Mn.

Raman spectroscopy is commonly used to estimate peak temperatures in rocks containing organic carbon. In geological settings such as fold-thrust belts, temperature constraints are particularly important as complex burial and exhumation histories cannot easily be modelled. Many authors have developed equations to determine peak tempertaures from Raman spectral parameters, most recently to temperatures as low as 75 °C. However, recent work has shown that Raman spectra can be affected by strain as well as temperature. Fold-thrust systems are often highly deformed on multiple scales, with deformation characterised by faults and shear zones, and therefore temperatures derived from Raman spectra in these settings may be erroneous. In this study, we investigate how the four most common Raman spectral parameters and ratios change through a thrust-stacked carbonate sequence. By comparing samples from relatively low-strain localities to those on thrust planes and in shear zones, we show maximum differences of 0.16 for I[d]/I[g] and 0.11 for R2, while FWHM[d] and Raman Band Separation show no significant change between low and high strained samples. Plausible frictional heating temperatures of faulted samples suggest that the observed changes in Raman spectra are not the result of frictional heating. We apply three equations used to derive the peak temperatures from Raman spectra to our data to investigate the implications on predicted temperatures between strained and unstrained samples. All three equations produce different temperature gradients with depth in unstrained samples. We observe that individual equations exhibit apparently varying sensitivities to strain, but calculated temperatures can be up to 140 °C different for adjacent strained and unstrained samples using the same temperature equation. These results have implications for how temperatures are determined in strained rock samples from Raman spectra.

As an endeavor to trace the origin of the active surface sites on La2Ce2O7 compound for OCM reaction, a dissection strategy is adopted in this work. In detail, the reaction performance of pure La2O3, CeO2, the physical mixture of La2O3 and CeO2 (La2O3+CeO2), and the combination of pure La2O3 and CeO2 with different orders in the reactor (La2O3-CeO2 or CeO2-La2O3) has been tested for OCM reaction under the same condition. Individual La2O3, CeO2 and their simple mixing/combination display much lower OCM performance than La2Ce2O7 compound, especially below 700 oC. Therefore, the reaction performance of La2Ce2O7 is not due to a simple accumulation of the two pure oxides. To achieve favorable OCM performance, La and Ce cations must be combined into a stable La2Ce2O7 compound possessing a disordered defective cubic fluorite structure with intrinsic oxygen vacancies. In situ Raman, CO2-TPD, EPR and XPS results have demonstrated on the surface of La2Ce2O7, much larger amount of both O2- species and moderate basic sites have been formed in comparison with the individual metal oxides or their simple mixing/combination, thus it exhibits the optimum reaction performance among all the catalysts.

Maltose and pectin-assisted low-temperature combustion modified sol–gel process was employed to synthesize nanopowders of Ce0.8Sm0.2O2−δ (SDC 20), Ce0.81Nd0.095Sm0.095O2−δ (NSDC). The sample's powder was sintered at 1250 oC for 6 h to form dense ceramics with a relative density greater than 95%. The Rietveld refinement of powder XRD patterns indicates a single-phase material with a cubic fluorite structure. The Raman spectroscopy studies confirm solid solution with evidence of more oxygen vacancies in sample NSDC to sample SDC 20. The SEM images of the samples show a high-dense surface with few pores. The EDX results confirm the sample's chemical composition. Impedance measurements were carried out to study electrical properties. The NSDC sample showed improved conductivity (3.06 × 10-2 S/cm at 600 °C) over SDC 20 (2.16 × 10-2 S/cm at 600 °C) with lower activation energy (0.81 eV). Specific grain (σ*g) and grain boundary (σ*gb) conductivity values were calculated using porosity corrections to the Bricklayer model.

Experimental and numerical studies are carried out to validate the potential of opposing Plasma Synthetic Jet (PSJ) for drag reduction for a hemisphere. Firstly, flow field changes of opposing PSJ are analyzed by comparing the experimental schlieren images and simulation results in a supersonic free stream of Mach number 3. As PSJ is a kind of unsteady pulsed jet, the shock standoff distance increases initially and then decreases under the control of PSJ, which corresponds to the change of the strength of PSJ. Accordingly, the amount of drag reduction of the hemisphere increases initially and then decreases. It is found that there is a short period of “drag rise” during the formation of PSJ before the drag reduction, which is induced by the generation of normal shock waves and the area difference of the cavity wall of PSJ Actuator (PSJA). Secondly, the effects of five parameters, including exit diameter, discharge energy of PSJA, Mach number, static pressure of incoming flow and angle of attack, on drag reduction of opposing PSJ were studied in detail by using numerical method. It is found that the Maximum Pressure Ratio (MPR) has a significant impact on the average drag reduction for a configuration-determined PSJA. For the configuration selected in this study, the flow field of opposing PSJ shows typical Short Penetration Mode (SPM) in a control cycle of PSJ when the MPR is less than 0.89. However, the flow field shows typical Long Penetration Mode (LPM) at some time when the MPR is bigger than 0.89. Relatively better drag reduction is achieved in this case.

Surface-enhanced Raman scattering (SERS) spectroscopy has been employed as a rapid analysis technology for food security inspection recently. Nowadays, it is still a great challenge to rapidly quantify multiple trace antibiotics potentially abused in aquaculture industry. In this work, a magnetic Ti3C2Tx/Fe3O4/Ag substrate was prepared for the development of a reliable rapid SERS quantification method for multiple trace sulfonamides in aquatic products. This magnetic substrate had good uniformity, reproducibility, stability and SERS activity. Moreover, this substrate could integrate the magnetic separation-enrichment and matrix clean-up without cross contamination, which endowed it with good selectivity and anti-interference capability during real sample analysis. The electromagnetic enhancement and chemical enhancement mechanism of this magnetic substrate were studied in detail to reveal its good separation-enrichment performance and SERS activity. Finally, a rapid SERS quantification method was established and practically applied for trace phthalic sulfathiazole (PST) and silver sulfadiazine (SSD) in aquatic products by using Ti3C2Tx/Fe3O4/Ag magnetic substrates. Trace PST and SSD could be actually detected and quantified as 55.9 μg/kg and 64.0 μg/kg in aquatic products respectively. Good recoveries of 83.9%-116% with relative standard deviations (RSDs) of 0.5%-3.2% for PST and 80.2%-102% with RSDs of 1.3%-5.8% for SSD were obtained. This work proposed an efficient and reliable method for rapid quantification of trace multiple sulfonamides in complex aquatic samples during food security inspection.

The work is dedicated to a research into the physicochemical aspects of carbon nanopowder production from the gas phase by the pyrolysis of the initial precursors in a cyclic adiabatic process in a flow-through chemical compression reactor (CCR). The method allows the production of carbon nanomaterials, such as the carbon nanoparticles and globular soot particles, as well, as the core-shell structures representing the 4–7 nm composite particles with a SiC crystal core covered with graphene layers. Products have controlled and reproducible properties, and output capacity of the method is sufficient for technological purposes. The nanopowders are characterized by high-resolution transmission electron (TEM) and scanning electron (SEM) microscopy, X-ray diffraction analysis and Raman spectroscopy. The nanomaterials were used to manufacture their aqueous suspensions - nanofluids, which have shown their effectiveness in enhancing oil recovery in oil displacement technologies.

This work presents the synthesis of Y2O3:Eu3+,xCa2+ (x = 0 mol%, 1 mol%, 3 mol%, 5 mol%, 7 mol%, 9 mol%, 11 mol% of Ca2+) nanophosphor with enhanced photoluminescence properties through a facile solution combustion method for optoelectronic, display, and lighting applications. The X-ray diffraction patterns (XRD) of the proposed nanophosphor reveal its structural properties and crystalline nature. The transmission electron microscope results (TEM) confirm the change in the shape of the particle and aggregation of particles after co-doping with Ca2+. Fourier transform infra-red spectroscopy (FTIR) and Raman vibrations also confirm the presence of Y-O vibration and subsequently explain the crystalline nature, structural properties, and purity of the samples. All the synthesized nanophosphors samples emit intense red emission at 613 nm (5D0→7F2) under excitation with 235, 394 and 466 nm wavelengths of Eu3+ ions. The photoluminescence (PL) emission spectra excited with 235 nm illustrates the highest emission peak with two other emission peaks excited with 466 and 394 nm that is 1.4 times higher than 466 nm and 1.9 times enhance by 394 nm wavelength, respectively. The emission intensity of Y2O3:Eu3+,xCa2+ (5 mol%) has been increased 8-fold as compared to Eu:Y2O3. Doping with Ca2+ ions enhances the emission intensity of Eu:Y2O3 nanophosphors due to an increase in energy transfer in Ca2+→Eu3+ through asymmetry in the crystal field and by introduction of radiative defect centers through oxygen vacancies in the yttria matrix. It has also been observed the optical band gap and the lifetime of the 5D0 level of Eu3+ ions in Y2O3:Eu3+,xCa2+ nanophosphor sample gets changed with a doping concentration of Ca2+ ions. Nanophosphor also reveals high thermal stability and quantum yield as estimating activation energy 0.25 eV and 81%, respectively. CIE, CCT, and color purity values (>98%) show an improved red-emitting nanophosphor in the warm region of light, which makes this material superior with a specific potential application for UV-based white LEDs with security ink, display devices, and various other optoelectronics devices.

Modeling the electromagnetic response of carbon nanotube (CNT) reinforced composites is inherently a three dimensional (3D) multi-scale problem that is challenging to solve in real-time for nondestructive evaluation applications. This article presents a fast and accurate full-wave electromagnetic solver based on a multi-layer dyadic Green’s function approach. In this approach, we account for the effects of the dielectric slab, where the CNTs are embedded, without explicitly discretizing its interfaces. Due to their large aspect ratios, the CNTs are modeled as arbitrary thin wires (ATWs), and the method of moment (MoM) formulation with distributed line impedance is used to solve for their coupled currents. The accuracy of the inhouse solver is validated against commercial method of moment (MoM) and finite element method (FEM) solvers over a broad range of frequencies (from 1 GHz to 10 THz) and for a wide range of dielectric slab properties. Examples of 100nm long vertical and horizontal CNTs embedded in a 1 μm thick lossy dielectric substrate are presented. The in-house solver provides more than 50 ✕ speed up while solving the vertical CNT, and more than 570 ✕ speed up while solving the horizontal CNT than a commercial MoM solver over the GHz to THz frequency range.

Recently, fabricating type-II vertical van der Waals (vdWs) heterostructure is a promising material for hydrogen production. The absorption capability, charge density distributions, band alignments and electronic properties of the monolayers and heterostructures are systematically investigated using computational studies. Using ab initio molecular dynamics, binding energy and phonon calculations, the stability of the heterostructures are verified. Both heterostructures are type-II materials, which can increase the separation of charge carriers. Moreover, the charge density difference and the potential drop across the interface of MSe2/BSe creates a high built-in electric field that can prevent the recombination of charge carriers. We found that the visible-light optical properties of both heterostructures are much enhanced with suitable bandgap energy for water splitting. The band alignment suggests that the heterostructures straddle water redox potentials in acid solutions (0

The first-principles calculations demonstrate that covalently bonded (cb) heterojunction and van der Waals (vdW) heterojunction can coexist in silicene/CeO2 heterojunctions, due to the different stacking patterns. Especially, the cb heterojunction with band gap of 1.97 eV, forms a type-II heterojunction, exhibits good redox performance and has high-effective optical absorption spectra, thus it is a promising photocatalyst for overall water splitting. Besides, for the vdW heterojunction, the Dirac cone of silicene is well kept on CeO2 semiconducting substrate, with a considerable energy gap of 0.43 eV, which can be an ideal material in building silicene-based electronic device. These results may open a new gateway in both of nanoelectronic device and energy conversion for silicene/CeO2 nanocomposites.

Two-dimensional (2D) materials with honeycomb, kagome or star lattice have been intensively studied because electrons in such lattices could give rise to exotic quantum effects. In order to improve structural diversity of 2D materials to achieve unique properties, here we propose a new quasi-2D honeycomb-star-honeycomb (HSH) lattice based on first-principles calculations. A carbon allotrope named HSH-C10 is designed with the HSH lattice, and its mechanical properties have been intensively investigated through total energy, phonon dispersion, ab initio molecular dynamic simulations, as well as elastic constants calculations. Besides the classical covalent bonds, there is an interesting charge-shift bond in this material from the chemical bonding analysis. Additionally, through the analysis of electronic structure, HSH-C10 is predicted to be a semiconductor with a direct band gap of 2.89 eV, which could combine the desirable characteristics of honeycomb and star lattice. Importantly, by modulating coupling strength, a flat band near the Fermi level can be obtained in compounds HSH-C6Si4 and HSH-C6Ge4, which have potential applications in superconductivity. Insight into such mixed lattice would inspire new materials with properties we have yet to imagine.

This work aims to evaluate the dynamic performance of a highly selective Ni-based surface during the oxidative dehydrogenation of ethane (ODH-C2). The catalyst comprises an in-house bimetallic mixed-oxide formulation with a Ni/Sn atomic ratio of 10. To corroborate its proper synthesis, it is characterized by TGA, AES, XRD, physisorption of N2 and TEM. The catalytic evaluation of the mixed oxide under dynamic conditions allows the proposition of a redox surface mechanism whose reliability is evaluated through a rigorous analysis, which is based on the development of a kinetic model and a robust experimentation program using a fully-automated micro-reaction unit and registering in-situ surface temperatures and continuous inline monitoring of oxygen and carbon dioxide. Experiments are carried out using a mixture of ethane or ethylene, oxygen and nitrogen as feedstock, at temperatures from 360 to 480 °C, total pressures from 100 to 500 kPa, and space-time values from 8.1 to 133.1 kgcat s molC2H6−1. Oxygen conversion ranges from 5% to 100% while the one for ethane varies from 5% to 60%. Besides, the selectivity and yield to ethylene vary from 30% to 90% and from 2% to 40%, respectively. The suitability of the redox mechanism is here assessed by evaluating statistical and phenomenological foundations, including Boudart’s criteria. Kinetic parameters, estimated by non-linear regression and using the reparametrized form of the Arrhenius and van’t Hoff equations, are phenomenologically well founded, such that changes of entropy and enthalpy of adsorption correctly describe the loss of mobility due to adsorption and the exothermic nature of the adsorption processes. Ethylene formation is the reaction demanding the lowest activation energy (Ea1 = 61.94 kJ mol−1), while the total oxidation of ethane is the path requiring the largest activation energy (Ea2 = 132.6 kJ mol−1). Concerning the adsorption enthalpy, ethylene exhibits the largest value ( − Δ H C 2 H 4 ° = 123.39 kJ mol−1), while carbon dioxide presents the lowest one ( − Δ H C O 2 ° = 42.00 kJ mol−1). Additional findings can be summarized as follows: activity and selectivity are recovered after the dynamic operation under oxidative conditions of the catalytic surface; carbon dioxide is identified as the only no desired byproduct; and hydroxyl surface species lead to the formation of water which affects the selectivity to ethylene, as well as the reaction rates. These findings are of interest for future studies directed at elucidating the performance of the Ni-based catalyst at larger scales, paving the way for the efficient design of the industrial reactor for the ODH-C2.

The linear stability analysis has been analyzed for an electrified liquid sheet confined between two symmetric dielectric movable ambient gas. The present study aims to estimate the planer jet systems response when applying a tangential electric field. The dispersion relations for varicose and sinuous modes have been formulated. The electrical Euler number and some flow parameters have been tested for their influence on the electrified liquid sheet instability. In other words, the effects of electric field on the dominant wave number, and instability range (cutoff wave number) are discussed. The results clarify that the tangential electric field has a stabilizing effect for sinuous mode over the whole range of gas velocity ratio. On the other hand, for varicose mode, the electric field slightly improves the system stability to a certain limit, but it has a great role in stability for higher values of gas velocity ratio.

In this work, thermodynamic and kinetic factors that affect formation and phase transformation process of different solid forms of levofloxacin hydrochloride were investigated in detail. Dynamic vapor sorption experiments (DVS) and varying temperature-powder X-ray diffraction (VT-PXRD) experiments were carried out to study moisture-dependent stability, thermal stability as well as the transformation process between Form I and Form II. Critical water activities of levofloxacin hydrochloride were determined in temperature range of 5.0–45.0 °C. Raman spectroscopy was applied to in situ monitor the temperature-induced phase transformation and the hydration process of levofloxacin hydrochloride, and one possible mechanism consisting of multiple chemical equilibria was proposed to analyze the effect of thermodynamic and kinetic factors on the formation and transformation of different solid forms. Results show that the anhydrate, Form II would transform to the monohydrate, Form I more easily with the increasing water content. And the transition point moves toward higher water contents as the temperature increases. The results suggested that, except for thermodynamic factors, kinetic factors also play an essential role in controlling the solid forms of polymorphic compounds.

The effect of substitution Pb2O3 by CuO content was studied for 75% Li2B4O7 + (25 − x)Pb2O3 + xCuO glass system where x = 0, 5, 10, 15, 20, and 25 wt%. The mechanical and radiation shielding properties were evaluated for the investigated glass samples. The mechanical properties included Young's, shear, bulk, longitudinal, Poisson ratio, and micro-hardness were computed theoretically based on the packing factor (Vi) and dissociation energy (Gi) of the metal oxides constituting the existing glass samples using the Makishima–Mackenzie model. The obtained results depicted the insertion of CuO enhances the different mechanical parameters up to 20 mol% of the investigated LBPCu glasses. Furthermore, the radiation shielding properties were studied for the investigated LBPCu glass using the Monte Carlo N-particle transport code (MCNP-5) simulation. MCNP-5 was used to detect the simulated linear attenuation coefficient (LAC) and then mass attenuation coefficient (MAC) and other factors based on various gamma-ray sources with energies of 0.24, 0.66, 1.17, 1.33, and 1.40 MeV. The results showed that LAC's highest value decreased from 0.578 to 0.320 cm−1 for glasses LBPCu0 and LBPCu25, respectively, at low energy of 0.284 MeV. Moreover, the effective and equivalent atomic numbers (Zeff and Zeq), buildup factor (EBF), and absorption buildup factor (EABF) were evaluated for the investigated LBPCu glass using the BXCOM program. The results revealed that the shielding properties of the investigated glasses improved by the insertion of CuO content.

The optical and thermal properties of a new class of fluoroindate glass with different erbium contents were investigated via Raman, transmission, and fluorescence spectroscopies, fluorescence decay curve analysis, and differential scanning calorimetry. The strength parameters of the samples were calculated using the Judd–Ofelt theory. The mid-infrared luminescence properties of erbium-doped fluoroindate glasses were studied, and a strong emission at 2.7 μm was obtained. Compared with the traditional ZBLAN glass, this glass has excellent emission properties, especially a longer fluorescence lifetime (7.09 ms) and larger emission cross-section (6.95 × 10−21 cm2) at 2.7 μm. The results indicate that fluoroindate glass is an attractive host for mid-infrared lasers and as a gain medium for optical amplifier applications.

In recent years, utilization of nano-technology in drugs and cancer growth treatment has produced a great deal of temptation in thermal properties of biological nanofluid, for example, blood with nanoparticles suspension. The objective of this research is to discover a MHD naturally bio-convective flow of non-Newtonian bio-nano-fluid containing blood as base fluid with ( A l 2 O 3 ) alumina nanoparticles suspension carrying effect of buoyancy, chemical reaction, moving microorganism and heat generation near stagnation region. The Buongiorno along Tiwari and Das nanofluid model is employed whereas Oldroyd-B model is capitalized for depicting the viscoelastic behavior of blood. The non-similarity transformations are exercised on governing nonlinear partial differential system (PDE’s) to transform them into system of non-dimensional PDE’s. After applying appropriate transformations the local non-similarity method via bvp4c algorithm is adopted to numerically deal with the problem. The significance of parameters such as Grashof numbers, magnetic field, Brownian motion, thermophoresis, Deborah numbers, Prandtl number, Schmidt number, Peclet number, heat generation/absorption number and chemical reaction on velocity, temperature, concentration and density of moving microorganism are computed in the graphical profiles to explain the physical state of problem. Physical quantities i.e. local Nusselt number, local Sherwood number and local microorganism density number are also calculated.

Developing dual-state luminophores (DSLs) with strong fluorescence in both the monomer and aggregate states is urgently needed but remains a huge challenge because most current luminophores are eit...

The present study proposes a segmented cooling-stream injection structure based on a certain coolant mass flow rate, and numerically investigates the effect of segmented cooling-stream injection on supersonic film cooling. The results indicate that without shock-wave impingement and with helium as the coolant, segmented cooling-stream injection can reduce the mixing between the mainstream and the cooling stream to produce better cooling performance than single injection, especially at larger coolant Mach numbers. However, with nitrogen as the coolant, the cooling effect of the segmented-injection system is very close to that of the single-injection system. Mixing at the impinging region is enhanced significantly when there is an incident shock wave. When the shock wave impinges between the two coolant inlets, segmented cooling-stream injection improves film cooling effectiveness in the midstream and downstream regions more than single injection because only part of the cooling stream undergoes the enhanced mixing effect of the shock wave. The advantage of segmented injection is reduced when the impinging region is behind the second coolant inlet. The further downstream the impinging region, the smaller the associated advantage.

This paper investigates the rate of transformation induced plasticity in TRIP steel (TRansformation-Induced Plasticity) after plastic straining by the use of Barkhausen noise emission. The samples were subjected to a variable degree of plastic straining and analysed by the use of conventional techniques such SEM, XRD, as well as microhardness in order to investigate residual stress and microstructural alterations initiated by the uniaxial tensile test. Barkhausen noise emission is analysed as a function of plastic straining as well as in the direction of the exerted load and interpreted with respect to the aforementioned microstructure and stress alterations. It was found that Barkhausen noise markedly decreases along with increasing plastic straining, up to 20%, followed by a strain region in which the evolution of Barkhausen noise reaches saturation. Samples after the tensile test exhibited marked magnetic anisotropy since the Barkhausen noise emission in the direction perpendicular to the tensile stress remained less affected. Apart from the effective value of Barkhausen noise, the Barkhausen noise envelopes were also analysed.

The equivalent elastic modulus is a parameter for controlling the deformation behavior of fractured rock masses in the equivalent continuum approach. The confining stress, whose effect on the equivalent elastic modulus is of great importance, is the fundamental stress environment of natural rock masses. This paper employs an analytical approach to obtain the equivalent elastic modulus of fractured rock masses containing random discrete fractures (RDFs) or regular fracture sets (RFSs) while considering the confining stress. The proposed analytical solution considers not only the elastic properties of the intact rocks and fractures, but also the geometrical structure of the fractures and the confining stress. The performance of the analytical solution is verified by comparing it with the results of numerical tests obtained using the three-dimensional distinct element code (3DEC), leading to a reasonably good agreement. The analytical solution quantitatively demonstrates that the equivalent elastic modulus increases substantially with an increase in confining stress, i.e. it is characterized by stress-dependency. Further, a sensitivity analysis of the variables in the analytical solution is conducted using a global sensitivity analysis approach, i.e. the extended Fourier amplitude sensitivity test (EFAST). The variations in the sensitivity indices for different ranges and distribution types of the variables are investigated. The results provide an in-depth understanding of the influence of the variables on the equivalent elastic modulus from different perspectives.

The pressure drop prediction of wet gas across single-orifice plate in horizontal pipes had been solved satisfactorily under an annular-mist flow in the upstream of orifice plates. However, this pressure drop prediction is still not clearly determined when the upstream is in an intermittent flow or stratified flow, which is corresponding to a region of low FrG (gas phase Froude number) in the flow pattern map of wet gases. In this study, the wet gas pressure drop across a single-orifice plate was experimentally investigated in the low FrG region. By the experiment, the flow pattern transition in the downstream of single-orifice plates, as well as the effects of FrG and FrL (liquid phase Froude number) on ΦG (gas phase multiplier), were determined and compared when the upstream is in the flow pattern transition and the stratified flow region, respectively. Prediction performances were examined on the available pressure drop models. It was found that no model could be capable of jointly predicting the wet gas pressure drop in the low FrG region with an acceptable accuracy. With a new method of correlating FrG and FrL simultaneously, new correlations were proposed for the low FrG region. Among which the modified Chisholm model shows the best prediction accuracies, with the prediction deviations of ΦG being within 7% and 3% when the upstream is in flow pattern transition and stratified flow region, respectively.

In this work, the effect of using baffles and vortex generators on the cooling performance of a gas turbine combustion chamber is numerically investigated. The RNG k-ɛ model is utilized in order to simulate the flow turbulence. The effects of baffles and vortex generator pitch, hydraulic diameter and bypass ratio on the Nusselt number and friction coefficient at different Reynolds number are studied. The cooling performance of applying baffles and vortex generators are also evaluated and compared based on the Performance Evaluation Criterion (PEC). The numerical results are verified with available experimental data. The results show that the pitch increment results in the decrement of the Nusselt number and the wall friction coefficient due to the lower vortices generation and the turbulence kinetic energy dissipation. Also, the Nusselt number is increased by increasing both the bypass ratio and the hydraulic diameter. It is also found that vortex generators and baffles improve the cooling performance of the gas turbine combustion chamber by 18.8% and 26% respectively through decreasing the external wall temperature.

Based on the effective continuum model, we study alternating-twist multilayer graphene system and emergence of magic angles and flat band topology. All the alternating-twist multilayer graphene system (from triple layers to few layers) are found to have flat bands at magic angles where the area of AA stacking equals n -fold ( n is an integer) electron cyclotron area. From the pseudo-Landau-level representation, there is always an isolated Dirac band in the alternating-twist graphene system constructed by odd number of layers. Since each pair of flat bands can be perceived as the zeroth pseudo-Landau-levels in two dimensional Dirac fermions, electron in the flat band pair can feel a pseudo-magnetic field with the same magnitude but the opposite sign. Calculated Chern number for each flat band is+1 (or -1) which can be tuned by twistingin the vicinity of magic angles or by gating. The concurrent appearance of strong correlation and band topology of flat bands in the alternating-twist multilayer graphene may pave an avenue for the new understanding of superconductivity observed in triple-layered graphene, and supply a new playground for realizing (quantum) anomalous Hall effect.

At present, electrospinning technology is a versatile and simple method for generating nano-scale membranes, and it provides attractive solutions in solving environmental problems and many energy problems. However, such films generally have low mechanical properties which limit their use in industry. Nanocellulose with excellent mechanical properties, high specific surface area, and renewable nature is an ideal green reinforcing material. In this paper, the cellulose nanocrystals (CNC) coatings on electrospun polyamide 6 (PA6) were prepared via coating method and explored as potential high-performance reinforced materials. The extraction of CNC and the performance of the composite membranes were studied by calculating the yield, scanning electron microscopy, 3D imaging, mechanical testing, and thermogravimetric analysis. Results show that the yield of CNC is impacted by various factors among which acid concentration is the most important. The CNC/PA6 composite film shows lower porosity and higher surface roughness than the pure PA6 membrane. With the increase of CNC concentration, lower porosity and higher surface roughness are obtained. With CNC coatings, tensile strength and Young s modulus of PA6 increase dramatically, while the tensile strain decreases obviously. The Young s modulus of the composite film has been increased by 250%. The composite membranes reveal high mechanical strength and low porosity, which can be applied infiltration and packaging.

Karbon atomlarının hekzagonal örgüde bir araya gelerek oluşturduğu tek atom kalınlığındaki grafen son yılların en yoğun araştırılan konularından bir tanesi olmasının yanı sıra yüksek elektrik ve ısı iletkenliği, yüksek ışık geçirgenliği, yüksek dayanım ve geniş yüzey alanı gibi birçok üstün özellikleri ile geniş bir yelpazede kullanım alanına sahiptir. Bu üstün özelliklere karşın grafenin sahip olduğu yüksek tabak direnci ve yasak enerji aralığının olmaması grafenin optoelektronik uygulamalarda kullanımını sınırlamaktadır. Grafenin bu dezavantajları grafen yapısına yapılan katkılamalarla aşılabilmektedir. Ancak, katkılı grafen sentez sürecince katkıcı seçimi ve sentez yöntemi çok önemli olmakla birlikte özellikle katkılamanın kalıcılığı ve homojenliği daha değerlidir. Bu çalışmada CVD sistemi kullanılarak bakır folyo üzerinde katkısız ve nitrojen katkılı grafen sentezi ve karakterizasyonu gerçekleştirilmiştir. Katkılı grafen sentezi için piridin kullanılmış olup, piridin hem karbon hem de nitrojen kaynağı olarak kullanılmıştır. CVD tekniğinin kullanımı hem homojen hem de kalıcı katkılama gerçekleştirilebilmesine imkan vermiştir. Çalışma kapsamında ayrıca piridine ek olarak sentez sırasında CVD sistemine düşük miktarda metan gaz akışı sağlanarak film kalınlığı optimize edilmiştir. Katkılı filmlerin karakterizasyonu kapsamında Raman spektroskopisi, Enerji Dağılımlı X-ışını spektroskopisi ve X-ışını foto elektron spektroskopisi teknikleri kullanılmış olup, film kalitesi, kalınlığı, homojenliği, katkılama oranı ve türü belirlenmiştir.

Owing to the exorbitant overpotential and serious carrier recombination of graphitic carbon nitride (g-C3N4), noble metal (NM) is usually served as the H2 evolution co-catalyst. Although the NM (such as Pt) nanoparticles can reduce the H2 evolution overpotential, the weak Van der Waals interaction between Pt and g-C3N4 makes against the charge transfer. Herein, the solvothermal method is developed to achieve semi-chemical interaction between Pt and g-C3N4 nanotube (Pt-CNNT) for fast charge transfer. Moreover, the generated in-plane homojunction of CNNT can accelerate charge separation and restrain recombination. Meanwhile, the metallic Pt is an excellent H2 evolution co-catalyst. Photo/electrochemical tests verify that the semi-chemical interaction can improve photogenerated charge separation and transferability of CNNT. As a result, the photocatalytic H2 evolution turnover frequency (TOF) of Pt-CNNT under visible light irradiation reaches up to 918 h−1, which is one of the highest in the g-C3N4-based photocatalysts. This work provides a new idea to improve the charge transfer for efficient photocatalytic H2 evolution.

Phase change dynamics under the rotational surface effects, area expansion and nanoparticle loading in the base fluid are explored for forced convective flow of hybrid nanofluid in a phase change packed bed installed cylindrical reactor. The study is performed with finite element method for different parameters of rotational Reynolds number, fluid stream Reynolds number and concentration of nanoparticle. The hybrid nanofluid properties are based on experimental data for binary particle of Al2O3-TiO2 in 40 % ethylene–glycol. Complete phase transition time is estimated with ANFIS based model. The recirculation zone due to the area expansion within the phase change installed region is controlled by the complex interactions between the forced flow, rotation of the surface and nanoparticle amount. Higher values of Reynolds number and nanoparticle concentration result in fast phase change process at rotational Reynolds number of 0 while the effects become reverse in the presence of rotations. Complete phase transition time reduces by about 49 % and 10.5 % at the highest Reynolds number and at the highest concentration in the absence of rotation while it is increased by about 88 % and 6.5 % when rotational effects are considered at the highest rotational speed. When only rotational effects are considered, phase change process completion time reduces by about 60 % at the highest speed.

The safety of grid-connected voltage-controlled inverter is threatened by transient angle instability due to fault. The impact of different active power control (APC) and reactive power control (RPC) on the inverters transient angle stability hasnt been fully investigated. To fill this gap, firstly, a unified model of the voltage-controlled inverter considering different APC and RPC is put forward. Based on the proposed unified model, the effect of different APC and RPC loops on the inverters transient angle stability are qualitatively analyzed by using equal area criterion (EAC). Then, the TS multimodeling method which is based on the Lyapunov function is applied to evaluate the effect of control parameters on the inverters transient angle stability quantificationally. Finally, the above analysis is verified based on an experiment. It is found that lowering inertia improves the inverters global stability but decreases the inverters first swing stability. Transient stability of the inverter can be improved by increasing damping component of the inverter. Transient angle stability of the inverter is influenced by the RPC loop. With the increase of the output voltage of the RPC loop, reference reactive power, and output voltage of the inverter, transient angle stability of the inverter can be improved.

The properties of two-dimensional (2D) materials are highly dependent on their phase and thickness. Various phases exist in tin disulfide (SnS2), resulting in promising electronic and optical properties. Hence, accurately identifying the phase and thickness of SnS2 nanosheets is prior to their optoelectronic applications. Herein, layered 2H-SnS2 and 4H-SnS2 crystals were grown by chemical vapor transportation and the crystalline phase of SnS2 was characterized by X-ray diffraction, ultralow frequency (ULF) Raman spectroscopy and high-resolution transmission electron microscope. As-grown crystals were mechanically exfoliated to single- and few-layer nanosheets, which were investigated by optical microscopy, atomic force microscopy and ULF Raman spectroscopy. Although the 2H-SnS2 and 4H-SnS2 nanosheets have similar optical contrast on SiO2/Si substrates, their ULF Raman spectra obviously show different shear and breathing modes, which are highly dependent on their phases and thicknesses. Interestingly, the SnS2 nanosheets have shown phase-dependent electrical properties. The 4H-SnS2 nanosheet shows a current on/off ratio of 2.58 × 105 and excellent photosensitivity, which are much higher than those of the 2H-SnS2 nanosheet. Our work not only offers an accurate method for identifying single- and few-layer SnS2 nanosheets with different phases, but also paves the way for the application of SnS2 nanosheets in high-performance optoelectronic devices.

Nature of carbon nanotubes (CNT’s) mechanical characteristics can only be disclosed through advanced studies. Carbon nanotubes show diverse features in radial and axial directions when studied geometrically. Since CNT’s have two dimensional symmetrical behavior and they are in cylindrical shape, they show strong electrical and thermal conductivity in base fluid. In order to develop energy equation, such characteristics must be kept in view, we nominate the heat flux model of Catteneo-Christov. Carbon nanotubes of singlewall and multiwall are analyzed and compared in base fluid of water. Cylindrical coordinates are used in mathematical formulation and modeling for the flow equations to be converted to partial differential equations. For solution and study of fluid equations shooting method and Keller box scheme are used. Our computations resulted in an increase in fluid temperature due to thermal relaxation time, while fluid temperature decreases with an increases in Prandtl number. Further more, porosity also has fluid velocity as its decreasing function. The results are displayed through tables and graphs.

Embargado hasta 31/01/2024 In this work, photocatalysts consisting of TiO2 supported on zeolite (USY62) were synthesized by sol-gel method and, subsequently, a noble metal (Pt, Au, or Ag) was incorporated by impregnation or photodeposition. Zeolite-TiO2 composites were characterized by SEM, TEM, XRD, N2 adsorption-desorption, Raman and UV–vis spectroscopy, and well-dispersed anatase TiO2 particles (ca. 10 nm) that exhibited a blue-shift in the UV–vis absorption due to the size quantization effect were produced. The photocatalytic activity of all zeolite-TiO2 composites was examined by the photoreforming of aqueous glycerol solution (10% w/w) under UV and solar-simulated radiation. The activity of the zeolitic photocatalysts decreased in the order Pt > Au > Ag, being catalysts prepared by photodeposition more active than those prepared by impregnation. Moreover, Zeolite-supported TiO2, led to a TiO2 with smaller deactivation in H2 production than unsupported TiO2, which can be ascribed to the small TiO2 particle size or an interaction zeolite-TiO2. All in all, a photocatalyst (USY-Ti-PPt) with TiO2 up to four times more active than unsupported TiO2 under UV radiation was prepared.

Compared with antiferroelectric (AFE) orthorhombic R phases, AFE orthorhombic P phases in NaNbO3 (NN) ceramics have been rarely investigated, particularly in the field of energy-storage capacitors. The main bottleneck is closely related to the contradiction between difficultly-achieved stable relaxor AFE P phase and easily induced P-R phase transition during modifying chemical compositions. Herein, we report a novel lead-free AFE ceramic of (1-x)NN-x(Bi0.5K0.5)ZrO3 ((1-x)NN-xBKZ) with a pure AFE P phase structure, which exhibits excellent energy-storage characteristics, such as an ultrahigh recoverable energy density (Wrec) ∼4.4 J/cm3 at x = 0.11, a large powder density PD ∼104 MW/cm3 and a fast discharge rate t0.9 ∼45 ns. The analysis of polarization-field response, Raman spectrum and transmission electron microscopy demonstrates that the giant amplification of Wrec by ≥177% should be mainly ascribed to the simultaneously and effectively enhanced AFE P-phase stability and its relaxor characteristics, resulting in a diffused reversible electric field-induced AFE P-ferroelectric phase transition with concurrently increased driving electric fields. Different from most (1-x)NN-xABO3 systems, it was found that the reduced polarizability of B-site cations dominates the enhanced AFE P-phase stability in (1-x)NN-xBKZ ceramics, but the almost unchanged tolerance factor tends to cause the AFE R phase to be induced at a relatively high x value.