This study examined the convective drying of red cabbage at temperatures ranging from 50 to 90 °C. Mathematical modeling was used to describe isotherms, drying kinetics and rehydration process. The effects of drying conditions on energy consumption and microstructure were also evaluated. The Halsey model had the best fit to the isotherm data and the equilibrium moisture was determined to be 0.0672, 0.0490, 0 0.0379, 0.0324 and 0.0279 g water/g d.m. at 50, 60, 70, 80 and 90 °C, respectively. Drying kinetics were described most accurately by the Midilli and Kuçuk model. Also, the diffusion coefficient values increased with drying temperature. Lower energy consumption was found for drying at 90 °C and the rehydration process was best described by the Weibull model. Samples dehydrated at 90 °C showed high water holding capacity and better maintenance of microstructure. These results could be used to foster a sustainable drying process for red cabbage.

Objectives: This article investigates the corrosion behavior and mechanical-property changes of S135, G105, and V150 drill pipe materials in a high-temperature-resistant, potassium amino poly-sulfonate drilling fluid, which has good lubrication performance and contains CO2/H2S, by applying an 80% yield-limit-load simulation. The results show that the CO2-corrosion behavior of G105, S135, and V150 drill pipes are obvious under the simulated constant-load-stress-corrosion environments at the wellhead, well-middle, and bottomhole positions. Compared to uncorroded drill pipes, S135 and V150 drill pipes have increased strength and yield ratios, decreased fracture elongation, and increased sensitivity to hydrogen embrittlement under H2S action, and V150 has a greater risk of stress-hydrogen embrittlement. The strength and yield ratios of G105-material drill pipes decrease, while the fracture elongation increases; the intensity-change amplitude levels are ranked V150 > G105 > S135, and the fr... [more]

A combined dispersed liquid−liquid microextraction (DLLME) and chromatography (GC) method was developed for the determination of 24 aromatic substances in rosemary hydrosol in this work. The pretreatment method of DLLME was optimized by carefully selecting the appropriate extraction agents, dispersants, and their respective amounts. With carbon tetrachloride as the extractant and acetone as the dispersant, the enrichment factor of DLLME is 13.3, and the 24 target substances such as eucalyptol, camphor and verbenone can be separated within 31 min and quantified by an external standard method using gas chromatography (GC). The correlation coefficient r2 of the linear regression equation is within the range of 0.9983 to 0.9991. The detection limit of the method was 0.02 mg/L, the recovery rate of the spiked solution was 76.4−118.4%, the relative standard deviation was 0.4−6.9% and the method was used to detect the semi-finished products of rosemary hydrosol and the finished rosemary hydro... [more]

Hard materials have found extensive applications in the fields of electronics, optics, and semiconductors. Parallel grinding is a common method for fabricating high-quality surfaces on hard materials with high efficiency. However, the surface generation mechanism has not been fully understood, resulting in a lack of an optimization approach for parallel grinding. In this study, the surface profile formation processes were analyzed under different grinding conditions. Then, a novel method was proposed to improve surface finish in parallel grinding, and grinding experiments were carried out to validate the proposed approach. It was found that the denominator (b) of the simplest form of the rotational speed ratio of the grinding wheel to the workpiece has a great influence on surface generation. The surface finish can be optimized without sacrificing the machining efficiency by slightly adjusting the rotational speeds of the wheel or the workpiece to make the value of b close to the ratio... [more]

This study deals with the synthesis and characterization of a series of hybrid photocatalysts consisting of different loadings of TiO2, Cd, and Fe on mesoporous SBA-15 material. The prepared samples were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and scanning electron microscopy (SEM), and tested for the removal of the neonicotinoid insecticide imidacloprid. The results showed that uncalcined 10% Cd-SBA-15 catalyst exhibited the best photocatalytic activity. The photocatalytic degradation of the imidacloprid was carried out in a batch photoreactor at different pH values, and in the presence or absence of additional compounds such as peroxymonosulfate (PMS) and peroxydisulfate (PDS). The best degradation results were achieved at a pH value of 6.5 with 10% Cd/SBA-15. The degradation performance increased with the addition of PMS and PDS. Based on the results of the experimental measurements, Cd/SBA-15 is a good candidate that can show a rea... [more]

The efficiency of the vapor phase crystallization (VPC) process in zeolite formation using mixtures of a natural source (obsidian) and common waste materials (red mud and fly ash) was analyzed. The aim was to demonstrate that water molecules available during this treatment control mainly the synthesis of sodalite, regardless of the raw material used, as long as it is rich in amorphous silica and alumina pre-fused with NaOH. The data indicate that increasing the temperature to generate steam from distilled water during the VPC process results in the continuous transformation of amorphous material into sodalite and, subordinately, cancrinite. The formation of the newly formed phases was monitored by powder XRD and SEM.

In addressing the issue of a low drawing rate in a steeply inclined and extremely thick coal seam, this study focused on the engineering background of the +575 horizontal working faces in the Wudong Coal Mine. By utilizing physical similarity simulation experiments, research was carried out on the top-coal-drawing rate and the gangue ratio at different coal-drawing intervals in horizontal segment mining for steeply inclined and thick coal seams, in which the relationships between the top-coal-drawing law and the drawing interval and technologies were revealed. The discrete element method was used to establish a numerical simulation model for the horizontal segment mining of steeply inclined and thick coal seams, and the roof-drawing law in the cases of the three-interval-group-of-support and drawing-once-every-two-support methods were analyzed before finally obtaining the optimal drawing technology. Through field practice, the coal-drawing effect of the technology was verified. The res... [more]

Inorganic phase-change materials (PCMs) with high melting points have great potential for thermal energy storage systems. Sodium chloride (NaCl) has a high melting point (801 °C) and high latent-heat-storage density (482 kJ/kg). However, it is difficult to encapsulate NaCl using a sintered ceramic shell because of its good wettability against ceramics and high volume-expansion capacity during melting. In this study, a novel NaCl/Al2O3 powder-composite structure was developed as highly stable PCM core material for highly stable encapsulation. The shape-retention performance and the mechanism of NaCl/Al2O3 powder-composite structure during melting were investigated. We have successfully fabricated a NaCl/Al2O3 powder-composite structure, which has a higher NaCl volume ratio of 80 vol% than conventional techniques. The gel-like network structure of Al2O3 particles in molten NaCl was a key structure to keep the shape of the composite ball and to prevent the evaporation of molten NaCl.

Life cycle assessment (LCA) is used to evaluate the environmental load of fibre composite manufacturing technologies in the shipyards industry in a frame of the Fibre4Yards (Horizon 2020) project. This paper is focused on the LCA of fibre-reinforced polymer (FRP) technologies used to produce all elements of the floating unit, i.e., the conventional vacuum infusion technology for the deck panel and adaptive mould process for superstructure panels, ultraviolet (UV) curved pultrusion process for the production of stiffeners, hot stamping technology for brackets, and three-dimensional (3D) printing and automatic tape placement (ATP) for pillars. Environmental impact was assessed based on standard indicators: Global Warming Potential, water consumption, and fossil resource scarcity. The results indicate that the total carbon footprint of analysed FRP technologies is mainly produced by the type of the materials applied rather than by the amount of energy consumed during the process.

In situ formation of TiB2−Mg2TiO4 composites was investigated by combustion synthesis involving the solid-state reaction of Ti with boron and magnesiothermic reduction of B2O3. Certain amounts of MgO and TiO2 were added to the reactant mixtures of Ti/B/Mg/B2O3 to act as the moderator of highly exothermic combustion and a portion of the precursors to form Mg2TiO4. Two combustion systems were designed to ensure that synthesis reactions were sufficiently energetic to carry on self-sustainably, that is, in the mode of self-propagating high-temperature synthesis (SHS). Consistent with thermodynamic analyses, experimental results indicated that the increase in pre-added MgO and TiO2 decreased the combustion temperature and propagation velocity of the flame front. MgO was shown to have a stronger dilution effect on combustion exothermicity than TiO2, because the extent of magnesiothermic reduction of B2O3 was reduced in the MgO-added samples. In situ formation of the TiB2−Mg2TiO4 composite wa... [more]

The comparison between similar materials and original coal rock is the basis for similar simulation experiments in coal mines. The differences in mechanical properties, acoustic characteristics, and damage laws between similar materials and the original coal rock are of great significance for similar simulation research, to reveal objective laws. First, materials similar to coal rock with similar theoretical ratios were taken as the object of research, and the sand−cement ratio, the carbon paste ratio, and the water content were determined by multivariate linear regression to accurately match the ratios. Second, by using acoustic emission and digital scattering technology to explore the acoustic law, deformation characteristics, and spatial feature similarities of the materials similar to coal rock, the acoustic emission evolution law of the original rock was found to be the same as that of the similar materials. Digital scattering was able to describe the localization of strain in the... [more]

Developing bifunctional oxygen electrode materials with superior activity for oxygen reduction (ORR) and oxygen evolution (OER) reactions is essential for advancing regenerative fuel cell and rechargeable metal−air battery technologies. This present work deals with the synthesis and characterization of electrocatalysts containing Pt and Ni nanoparticles supported on nitrogen-doped mixed metal oxides (Mn2O3-NiO) and the systematic evaluation of their bifunctional ORR/OER performance in an alkaline medium. These electrocatalysts have been successfully synthesized by a simple and fast microwave method. PtNi/Mn2O3-NiO-N with a binary metal oxide-to-N ratio of 1:2 demonstrated the best performance among the studied materials regarding bifunctional electrocatalytic activity (∆E = 0.96 V) and robust stability.

Biochar, a carbon-dense material known for its substantial specific surface area, remarkable porosity, diversity of functional groups, and cost-effective production, has garnered widespread acclaim as a premier adsorbent for the elimination of heavy metal ions and organic contaminants. Nevertheless, the application of powdered biochar is hindered by the challenges associated with its separation from aqueous solutions, and without appropriate management, it risks becoming hazardous waste. To facilitate its use as an immobilization medium, biochar necessitates modification. In this investigation, sodium alginate, celebrated for its superior gelation capabilities, was amalgamated with polyvinyl alcohol to bolster mechanical robustness, thereby embedding biochar to formulate sodium alginate biochar microspheres (PVA/SA-FMB). A meticulously designed response surface methodology experiment was employed to ascertain the optimal synthesis conditions for PVA/SA-FMB. Characterization outcomes un... [more]

The present research aims at determining the axial buckling load of stiffened multilayer cylindrical shell panels made of functionally graded graphene-reinforced composites (FG-GPL RCs). Rings and stringers are applied as stiffening tools for shell panels, whose elastic properties are determined according to the Halpin−Tsai relations. The virtual work principle and finite element approach are implemented here, according to a first-order shear deformation theory (FSDT) and Lekhnitskii smeared stiffener approach, in order to determine the governing equations of the stability problem. Four different dispersions of nanofillers are assumed in the thickness direction, including the FG-X, FG-A, FG-O, and UD distributions. A large systematic investigation considers the effect of different geometric and material parameters on the buckling loads and mode shapes of the stiffened FG-GPL RC cylindrical shell panel, primarily the dispersion and weight fractions of the nanofiller, the number of rings... [more]

The potential of the supercritical antisolvent micronization (SAS) technique was evaluated for the production of CaO-based particles with a size and a physical structure that could enable high performance for CO2 capture through the calcium looping process. Two sources of calcium derivative compounds were tested, waste marble powder (WMP) and dolomite. The SAS micronization of the derivate calcium acetate was carried out at 60 °C, 200 bar, a 0.5 mL min−1 flow rate of liquid solution, and 20 mg mL−1 concentration of solute, producing, with a yield of more than 70%, needle-like particles. Moreover, since dolomite presents with a mixture of calcium and magnesium carbonates, the influence of the magnesium fraction in the SAS micronization was also assessed. The micronized mixtures with lower magnesium content (higher calcium fraction) presented needle-like particles similar to WMP. On the other hand, for the higher magnesium fractions, the micronized material was similar to magnesium aceta... [more]

Sodium sulfate (Na2SO4) is used in the ecofriendly production of sodium sulfide (Na2S) through H2 reduction, thereby facilitating the valorization of Na2SO4. However, studies on this technique remain at the laboratory stage. This paper proposes a novel process involving the external circulation of Na2S in a dilute-phase fluidized system to address the low-temperature eutectic formation between Na2S and Na2SO4 during the H2 reduction of Na2SO4 to Na2S. The process aims to increase the reaction temperature of the Na2SO4 while reducing the volume of the liquid phase formed to prevent sintering blockages and enhance the reduction rate. In a proprietary experimental setup, the H2 reduction process in a dilute-phase fluidized system was investigated. The Na2S/Na2SO4 ratio and reaction temperature were determined to be critical factors influencing the Na2SO4 reduction rate. The melting point of the system increased and the amount of liquid phase produced decreased as the Na2S content was incr... [more]

Atomic Force Microscopy (AFM) nanoindentation is a powerful technique for determining the mechanical properties of soft samples at the nanoscale. The Hertz model is typically used for data processing when employing spherical indenters for small indentation depths (h) compared to the radius of the tip (R). When dealing with larger indentation depths, Sneddon’s equations can be used instead. In such cases, the fitting procedure becomes more intricate. Nevertheless, as the h/R ratio increases, the force−indentation curves tend to become linear. In this paper the potential of using the linear segment of the curve (for h > R) to determine Young’s modulus is explored. Force−indentation data from mouse and human lung tissues were utilized, and Young’s modulus was calculated using both conventional and linear approximation methods. The linear approximation proved to be accurate in all cases. Gaussian functions were applied to the results obtained from both classic Sneddon’s equations and the s... [more]

Using slow-release fertilizer is one of the sustainable strategies to improve the effectiveness of fertilizers and mitigate the environmental pollution caused by excess usage of fertilizer. In this study, a slow-release urea fertilizer with water retention and photosensitivity properties was prepared by a two-step method. It was characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy and an infrared camera. This fertilizer can prolong the release period of urea, improve water-retention capacity of soil, and carry out photothermal conversion under illumination. Comparing four release kinetics models, the Ritger−Peppas model was the best fitting model for releasing behavior in soil, and diffusion followed the Fickian mechanism. The application of fertilizer on winter wheat was carried out to intuitively evaluate the fertilizer’s effects on promoting plant growth and resisting water stress. Thus, this study provides a new strategy... [more]

In order to reduce the failure accidents caused by the insufficient strength of fracturing string joints, theoretical calculation and string design methods were adopted to conduct finite element calculations on commonly used long circular threads. The distribution laws of stress and contact pressure of long round threads were obtained, a non-standard special thread was designed, and a finite element model of the joint of the casing was established. Considering different make-up torques, tensile loads, and tensile torque loads within a certain range, the stress variation law of the special casing threaded joint under this design size was analyzed. Finally, the stress and contact pressure variation law on the threaded tooth was analyzed under different structures, working conditions, and wall thickness parameters. The thread strength and sealing function were compared under various parameters. The results showed that the smaller the wall thickness of the joints, the greater the contact p... [more]

Media thermal conductivity is important in various heat-transfer processes. Many conventional fluid conductors suffered low conductivity and environmental issues. Therefore, research was active in finding out alternative systems, mostly relying on aqueous liquids that are low-cost and ecofriendly. After the emergence of carbon nanotubes (CNTs), with their many special structural, electrical and thermal properties, they have been examined for many applications, including heat-transfer processes. Adding CNTs to water yields CNT aqueous nanofluids that have been widely investigated as heat-transfer media. The literature shows that CNT addition improves water thermal conductivity and other water properties, such as viscosity, surface tension, freezing point and boiling point. The literature also shows that nanofluid thermal conductivity improvement is affected by CNT type and concentration, in addition to other factors such as surfactant addition. All these subjects were widely described i... [more]

The paper shows the expediency of supplementing the balance simplex method by calculating the number of free variables of separation flowsheets containing recycle flows. The need to determine and set the free variables that provide lower energy consumption when calculating the material balance of flowsheets with recycling is justified. The problem of material balance multivariance is illustrated, and ways to solve it are shown with the example of separation flowsheets for two ternary mixtures: n-butanol + water + toluene and n-butanol + butyl acetate + water. Separation flowsheets containing three distillation columns and a liquid−liquid separator are proposed for both systems. The dependence of the recycle flow values and the energy consumption of distillation columns and separation flowsheets on the selection and setting of values of free variables in solving the balance problem is shown. The dependence of energy consumption on the composition of the original mixture is studied for a... [more]

The pyrolysis of three different biomasses, rice husk (RH), zoita wood sawdust (ZW) and pine wood sawdust (PW), was studied at 500 °C in a multipurpose unit at the bench scale to determine the yields of the different products and the compositions and properties of the liquid products, with particular emphasis given to the alquitranous fractions (tars). It was possible to link the characteristics of the tars with the compositions of the raw biomasses and verify their potential in various applications. The analytical techniques employed in the characterization of biomasses included lignin, celulose and hemicellulose analysis, ultimate and proximate analysis and thermogravimetry−mass spectrometry analysis (TG-MS). Elemental analysis, gas chromatography−mass spectrometry (GC-MS), nuclear magnetic resonance spectroscopy (1H NMR), Fourier transform infrared spectroscopy (FTIR) and size exclusion chromatography (SEC) were used to characterize the tars. The tar yields were 1.8, 7.4 and 4.0 %wt... [more]

In order to remove high-concentration emulsified oil from wastewater, a chitosan-based magnetic flocculant, denoted as FS@CTS-P(AM-DMC), was employed in this present study. The effects of factors including the magnetic flocculant dose, pH values, and coexisting ions were investigated. A comparative dosing mode with the assistance of polyacrylamide (PAM) was also included. The evolution of floc size was studied using microscopic observation to investigate the properties of flocs under different pH values and dosing modes. Particle image velocimetry (PIV) and extended Deryaguin−Landau−Verwey−Overbeek models were utilized to illustrate the distribution and velocity magnitude of the particle flow fields and to delve into the mechanism of magnetic flocculation. The results showed that FS@CTS-P(AM-DMC) achieved values of 96.4 and 74.5% for both turbidity and COD removal for 3000 mg/L of simulated emulsified oil. In the presence of PAM, the turbidity and COD removal reached 95.7 and 71.6%. In... [more]

Protective coatings are typically applied to enhance their resistance to corrosion. There is considerable research on the corrosion resistance of coated casings. However, few research studies have focused on the erosion resistance on coated casings. In this work, the erosion resistance of resin- and metallic-coated casings in liquid−solid two-phase fluids were investigated using a self-made erosion facility. The results show that the resin coating tends to peel off the material base in the form of brittle spalling or coating bulge in the high-speed sand-carrying liquid. Both resin and metallic coatings were broken through within 20 min in a liquid−solid two-phase flow environment. Compared to resin coatings, metallic coatings exhibit weaker erosion resistance in similar liquid−solid flow. Through the analysis of experimental results and fitted curves, empirical constants for materials and sand content influencing factors were determined using non-dimensional processing. The erosion pre... [more]

Nitrogen fixation, the conversion of atmospheric nitrogen into biologically useful compounds, is crucial for sustaining biological processes and industrial productivity. Recent advances have explored plasma-assisted processes as an innovative approach to facilitate nitrogen fixation. This review offers a comprehensive summary of the development, current state of the art, and potential future applications of plasma-based nitrogen fixation. The analysis encompasses fundamental principles, mechanisms, advantages, challenges, and prospects associated with plasma-induced nitrogen fixation.