With little to no natural fracture development and the high calcite content in porous carbonate reservoirs, for multistage acid fracturing, different fluids are used to form a viscous fingering in the fracture, thus enhancing the degree of nonuniform etching. However, existing studies on multistage acid fracturing mainly focused on the combination of fracturing fluid and acid, which is less specific for porous carbonate rocks. Here, the rheological properties of five fluids, including guar-based fluid, cross-linked guar, gelled acid, cross-linked acid, and diverting acid, were studied at each temperature condition, and the viscosity relationship between each fluid was clarified. Based on the rheological properties, the differences between the seven liquid combinations on the etched morphology of the fracture walls were studied and analyzed. The conductivity of the seven acid-etched fractures under different closure stress was simulated. The experimental results showed that the viscosit... [more]

3D printing is more and more often used for the development and manufacturing of electronic devices and components. These applications require knowledge about the dielectric properties of the used materials—in particular minimal and stable values of relative permittivity and dielectric losses. The paper deals with the testing of the relative permittivity and loss factor of materials as follows: PLA (in three dye modifications), PET-G, and ABS and ASA in the frequency range 1−100 MHz. It was found that relative permittivity varied between 2.88−3.48 and the loss factor was in the range 0.03−4.31%. In terms of relative permittivity, all tested materials manifested a slight decline with increasing frequency. Concerning loss factor PLA (colorless) and ABS were proven to be more suitable for electrotechnical application due to the lower values and frequency dependences of the loss factor. Different results were observed in PLA-Silver and PLA-Metallic green. These materials showed a higher fr... [more]

As a versatile and valuable intermediate, furfuryl alcohol (FOL) has been widely used in manufacturing resins, vitamin C, perfumes, lubricants, plasticizers, fuel additives, biofuels, and other furan-based chemicals. This work developed an efficient hybrid strategy for the valorization of lignocellulosic biomass to FOL. Corncob (75 g/L) was catalyzed with heterogenous catalyst Sn-SSXR (2 wt%) to generate FAL (65.4% yield) in a deep eutectic solvent ChCl:LA−water system (30:70, v/v; 180 °C) after 15 min. Subsequently, the obtained FAL liquor containing FAL and formate could be biologically reduced to FOL by recombinant E. coli CF containing aldehyde reductase and formate dehydrogenase at pH 6.5 and 35 °C, achieving the FOL productivity of 0.66 g FOL/(g xylan in corncob). The formed formate could be used as a cosubstrate for the bioreduction of FAL into FOL. In addition, other biomasses (e.g., sugarcane bagasse and rice straw) could be converted into FOL at a high yield. Overall, this hy... [more]

mRNA-based therapeutics are predicted to have a bright future. Recently, a B2C study was published highlighting the critical bottlenecks of mRNA manufacturing. The study focused on supply bottlenecks of various chemicals as well as shortages of skilled personnel. The assessment of existing messenger ribonucleic acid (mRNA) vaccine processing shows the need for continuous manufacturing processes that are capable of about 80% chemical reduction and more than 70% personnel at factor five more efficient equipment utilization. The key technology to solve these problems is both a higher degree of automation and the maximization of process throughput. In this paper, the application of a quality-by-design process development approach is demonstrated, using process models as digital twins. Their systematic application leads to both robust optimized process parameters, with an increase in productivity of up to 108%, and sophisticated control concepts, preventing batch failures and minimizing the... [more]

The machining of glass-fiber-reinforced composites is complex due to their heterogeneous structures. Research has indicated that high-speed machining, at high spindle speeds and feed rates, not only increases productivity but also reduces drilling defects, such as delamination. However, there are several challenges with high-speed machining, such as the heat generated during drilling between the drill tool and chip contact surfaces that can result in hole size errors. Therefore, it is essential to determine the optimum drilling parameters. This paper presents an innovative hybrid optimization approach called Grey Entropy Fuzzy. This approach is a combination of entropy-based weight integrated Grey Relation analysis and fuzzy logic. With the consideration of all responses simultaneously, an optimum machining combination was obtained at a spindle speed of 12,000 rpm and a feed rate of 0.02 mm/rev using a drill bit with a point angle of 118° and a drill diameter of 6 mm.

The calculation of carbon emissions is important to determine the carbon footprint and environmental impact of manufacturing processes to assess which steps could be further optimized and make processes greener and more sustainable. A previously published holistic approach to carbon footprint calculation was applied in conventional and laser-based material removal processes to determine which is the most carbon intensive one. The carbon footprint and environmental impact were calculated and the results show that conventional drilling was more carbon intensive than laser-based drilling, while the reverse was true for the case of laser-based grooving and conventional milling. This is because the cutting forces in conventional milling are higher than the cutting forces in conventional drilling due to increased mechanical resistance from the material in the first case. In the case of laser-based processes, the energy consumption is linked to material absorptivity which remained the same in... [more]

Thallium (I) was removed from aqueous solution by using gamma-alumina nanoparticles (γANPs) materials as nano adsorbents. Varied experimental conditions such as adsorbent dose, agitation time, initial concentration, pH, and temperature effects were carried out in batch conditions in view of the optimization of thallium (I) adsorption and the identification of the adsorption mechanisms in the system γANPs-Tl. The pH effect indicated a remarkable increase in the quantity of Tl(I) removed for pH values ranging from 4 to 8, an almost constant magnitude for pH values between 8 and 10, and a decrease for pH values above 10. Considering an initial Tl(I) concentration of 20 µg/L and an adsorbent dose of 1 g/L at a pH value of 8.5, the removal was achieved at 95.12 ± 0.02% efficiency. The pseudo-second-order kinetics and the Freundlich isotherm perfectly described the adsorption mechanism. The process of thallium (I) adsorption reaction, as highlighted by thermodynamic investigations, was found... [more]

Volcanic activity is characteristic of seismic zones. Consequently, volcanic material form part of the landscape in places where earthquakes are common natural phenomena. As volcanic wastes (VW) show pozzolanic activity, the substitution of manufactured Portland cement (PC) with VW is clearly a desirable option not only from an economical point of view but also to reduce the CO2 fingerprint. Therefore, designing concretes with volcanic Portland cements (VPC) clearly contributes to cleaner cement production. Construction and building activities in seismic zones need to use a specific kind of concrete—self-compacting concrete (SCC). The challenge we focused on was the design of SCC using VPC. The flow behavior of SCC is characterized by low yield stress, high plastic viscosity, and shear-thickening behavior at high shear. However, obtaining these striking properties of the concrete is not easy with traditional concrete flow tests (Abrams cone, etc.). Moreover, these methods are very cost... [more]

Nowadays, energy saving, and green sustainability are influencing the development of all industries, including the construction industry. In recent years, geopolymeric cement and concrete have become hot topic materials as a replacement for traditional OPC; this work carried out orthogonal experiments to identify four potential factors affecting the basic properties of the metakaolin-geopolymeric cement specimens. The results showed that the metakaolin and activator contents were the two primary influencing factors. Given the importance of studying the durability of building restoration materials in harsh environments, this experiment focused on testing the bond strength, permeability resistance, sulphate corrosion resistance, and freeze-thaw resistance of metakaolin geopolymer pastes with different proportions of metakaolin dopant and alkali activator content. The findings are that durability of the formed specimens significantly improved when suitable metakaolin and activator content... [more]

This paper investigates bending and compressive strengths as mechanical characteristics of cement-based repair mortar containing nano-silica (NS) and micro-silica (SF) as cement replacements particles and polyvinyl alcohol (PVA) fibers. The mentioned materials were added to the mortar in three different conditions, including single (just one material), binary (mixture of two admixtures), and ternary (mixture of all three admixtures) modes. The use of PVA fibers, nano-silica and micro-silica in the triple combination of a cement-based mortar is the primary objective of the current research. In total, 28 mix designs with various percentages of particles and fiber were employed in the current study, and 112 different specimens were prepared to conduct the experimental research. The compressive and flexural strength results have been selected as the criteria for obtaining the optimum mix design for each condition. In order to specify the mechanical characteristics of specimens, a compressi... [more]

The search for and design of high-performance electrode materials is always an important topic in rechargeable batteries. Using a global structure prediction method together with first-principles calculations, a free-standing two-dimensional B2C3P monolayer with honeycomb structure was identified. The stability of the B2C3P monolayer was confirmed by cohesive energy, phonon curves, and ab initio molecular dynamics calculations. Of note, the B2C3P monolayer was demonstrated to be metallic, which shows excellent performance for Li-ion batteries. For example, the B2C3P monolayer also exhibited a metallic characteristic after Li adsorption, therefore the ability to keep good electrical conductivity during battery operation. Furthermore, when a B2C3P monolayer is used as a lithium-ion battery anode, it shows an ultra-high theoretical capacity of 3024 mAh/g, and a comparatively low diffusion barrier of 0.33 eV. All calculated results showed that the B2C3P monolayer is an appealing anode mate... [more]

Deep mining has started in the Huaibei mining area, and the serious threat of high confined water on the floor to the coal seam is gradually increasing. Based on the deep confined water mining project at working face II633 of the Hengyuan coal mine, this paper theoretically analyzes the damage depth of the floor and the risk of water inrush from the floor. The best proportion of grouting materials was quantitatively optimized by indoor experiments, and an industrial field test was conducted to judge the grouting effect. The results show that the failure depth of the bottom plate calculated by theoretical analysis is 31.73 m; a single factor test and a response surface optimization design method determined the best value of each index: water cement ratio 0.8, bentonite 2%, water reducer 0.6%, sodium silicate 2%. The damage depth of the bottom plate after grouting is 18.83~20 m, according to the field monitoring by the strain method. The optimized slurry significantly reduces the damage... [more]

This study provides evidence on the stability of vitamin K1 (VK) in the form of phytomenadione, in the absence and presence of a therapeutic preparation, as the gold nanoparticles (AuNPs), under the effect of sodium halide ions. The degradation susceptibility of the two compounds was assessed individually and in mixtures by cyclic voltammetry and electrolysis at a constant current density assisted by UV-Vis spectrophotometry. Their interactions with the halide ions differently impact on the electrochemical processes as follows: (i) the fluoride ions weakly affects the VK/AuNP stability and compatibility; (ii) the presence of chloride ions leads to VK/AuNP stability, for a short time and restrictive compatibility; (iii) bromide ions induce instability and incompatibility of the VK/AuNP system; (iv) spontaneous interactions between VK/AuNPs and iodide ions take place, consequently defining as an unstable and incompatible system.

Microorganism biomass is a sustainable and innovative source of biopolymers, such as proteins and polysaccharides, that is suitable for the development of biodegradable films. The aim of this research was to evaluate the synthesis, morphology, rheology, and morphological and mechanical properties on the production of edible biofilms based on water kefir grains, and compare them with edible films based on thermoplastic compounds from starch (TPS) obtained from taro (Colocasia esculenta) and cassava (Manihot esculenta). Edible biofilms were prepared in solution with 30% wt/wt glycerol relative to starch mass and kefir grain biofilms using the casting method. A stationary rheological analysis was performed on the film-forming suspensions of kefir, taro starch, and cassava starch. Once the films were obtained, a physicochemical and morphological characterization was carried out. Results of the characterization showed the following main aspects: The results indicated an increase in biomass... [more]

In this research, the extraction with supercritical carbon dioxide (SC-CO2) and the subsequent impregnation of the extracted bioactive compounds from Zataria multiflora Boiss (Z. multiflora) into polylactic acid (PLA) films was investigated. The effects of temperature (318 and 338 K), pressure (15 and 25 MPa) and cosolvent presence (0 and 3 mol%) on the extraction yield were studied. The SC-CO2 assisted impregnation runs were carried out in a discontinuous mode at different pressure (15 and 25 MPa), temperature (318 and 328 K), and time (2 and 8 h) values, using 0.5 MPa min−1 as a constant value of depressurization rate. ANOVA results confirmed that pressure, temperature, and time influenced the extraction yield. Moreover, antioxidant activities of extracts of Z. multiflora were evaluated using 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assays. In addition, the antibacterial activities of the extracts were screened against standard strains of Staphylococcus aureus (S. aure... [more]

Up to now, a great number of catalysts have been reported that are active in the oxidation of volatile organic compounds (VOCs). However, supported noble-metal catalysts (especially Pt-based catalysts) are still the most excellent ones for this reaction. In this study, Pt species supported on γ-Al2O3 and ranging from single-atom sites to clusters (less than 1 nm) and 1−2 nm nanoparticles were prepared and investigated for oxidizing C2H4. The Pt-loaded γ-Al2O3 nanoflakes (PtAl-NF) and Pt-loaded γ-Al2O3 nanowires (PtAl-NW) were successfully prepared. The samples were characterized using XRD, TEM, XPS, HAADF-STEM, and in situ DRIFTS. Based on in situ DRIFTS, a simple surface reaction mechanism was developed. The stable intermediates CO on single-atom Pt, subnanometer Pt particles, and fully exposed Pt clusters could be explained by the strong binding of CO molecule poisoning Pt sites. Moreover, the oxidation of C2H4 was best achieved by Pt particles that were 1−2 nm in size and the cataly... [more]

Mo-Si compound-based ultrahigh temperature structural material (UHTM) is a new high-temperature structural material with great potential due to its high melting point, high hardness, and suitable density. As an important material to meet the demands of advanced high-temperature structural applications in the range 1200−1600 °C, in oxidizing and aggressive environments, it has attracted the attention of researchers in aerospace, energy, chemical industry, machinery, mechanical metallurgy, and other fields. This study could provide a reference for the research and application of Mo-Si intermetallic compounds as UHTMs. Based on their crystal structure and properties, we summarized the preparation, limitations, and modification methods of Mo-Si intermetallic compounds and reviewed the research progress in their toughness reinforcement and medium-temperature resistance improvement. Based on the literature review, there has been a certain level of progress in the research on modification of... [more]

The failure of a 101.6 mm drill pipe was studied by combining experimental testing and finite element simulation. The macro analysis, metallographic structure and energy spectrum, chemical composition and a mechanical property test of the failed drill pipe sample were firstly carried out. Then, a three-dimensional finite element model of drill pipe failure was established based on the experimental results. Finally, the failure mechanism of drill pipe was analyzed and the mitigation measures were put forward. The results showed that solids settling sticking was the direct cause of fracture failure of the drill pipe joint. Due to the violent friction and wear between the drill pipe joint and the settled sand, the large amount of heat generated caused the microstructure of the joint material to undergo phase transformation and the bearing capacity to be reduced. Finally, fracture occurs under tensile and torsional loads.

Using single metal salts of zirconium, lanthanum, and iron as raw materials and sodium alginate as a cross-linking agent, a new composite adsorbent was prepared via the co-precipitation method and embedding immobilization technology, and its phosphorus adsorption performance in wastewater was evaluated. Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) were used for characterization, and a 0.5 mol·L−1 sodium hydroxide solution was used to regenerate the adsorbent. The experimental results demonstrated that the adsorption rate reached 99.88% when the wastewater volume was 50 mL, the initial concentration of phosphorus-containing wastewater was 5 mg·L−1, the pH was 5, the dosage of composite adsorbent was 0.2 g, and the adsorption time was 200 min. The prepared adsorbent could reduce the initial phosphorus concentration of 5 mg·L−1 to 0.006 mg·L−1 in simulated wastewater, and from 4.17... [more]

In aero-engines, the rotor systems are frequently designed with multistage discs, in which the discs are fastened together through bolted joints. During operation, rotating machines are susceptible to rotor−stator rubbing faults. Those bolted joints are subjected to friction and impact forces during a rubbing event, leading to a dramatic change in mechanical properties at the contacting interfaces, influencing the rotor dynamics, which have attracted the attention of scholars. In the present work, a mathematical model, which considers the unbalance force, rotor dimensional properties, nonlinear oil-film force and rub-impact effect, is developed to study the bifurcation and stability characteristics of the bolted joint rotor system containing multi-discs subjected to the rub-impact effect. The time-domain waveforms of the system are obtained numerically by using the Runge−Kutta method, and a bifurcation diagram, time domain waveforms, spectrum plots, shaft orbits and Poincaré maps are a... [more]

Hydrochars are an alternative form of biochar produced by hydrothermal carbonisation (HTC), a potentially cheaper and greener method. In this paper, the effect of multiple variables on hydrochar properties was investigated. Waste biomass was converted to hydrochar via microwave-assisted hydrothermal carbonisation. The variables were temperature, solution ratio (water-biomass ratio), time, particle size, pH and acetone washing. The measured properties were yield, carbon, oxygen and ash content, higher heating value (HHV), carbon and energy recovery and dye and water adsorption. Feedstock significance was investigated using apple, wheat, barley, oat and pea straw. The investigation into this specific combination of variables and feedstock has not been done before. HTC increased carbon content (~60%), HHV (~24 MJ/kg) and water adsorption and reduced oxygen content and dye adsorption. Thermal analysis suggested hydrochars were not suitable for sequestration. Decreasing the solution ratio w... [more]

The handling of bulk solids in the form of powders is a fundamental process in a wide range of manufacturing industries, such as the automotive, aerospace, food, and healthcare sectors. All these sectors employ additive manufacturing (AM), as it enables the production of complex parts in a short amount of time. Thus, it is considered an established method for developing an agile manufacturing environment that can drastically reduce the lead time from conception to the production stage. At the same time, powder is a unique material sensitive to environmental and machine conditions; hence, establishing an optimal configuration is not straight-forward. This work presents a discrete element method (DEM) simulation of an experimental dosing system used in AM. We introduce a robust workflow that correlates suitable experimental data with simulation results, establishing models of real powders with different flowability. The results showed an excellent agreement between the experimental data... [more]

This review covers the operating conditions for extracting top value-added chemicals, such as levulinic acid, lactic acid, succinic acid, vanillic acid, 3-hydroxypropionic acid, xylitol, 2,5-furandicarboxylic acid, 5-hydroxymethyl furfural, chitosan, 2,3-butanediol, and xylo-oligosaccharides, from common lignocellulosic biomass. Operating principles of novel extraction methods, beyond pretreatments, such as Soxhlet extraction, ultrasound-assisted extraction, and enzymatic extraction, are also presented and reviewed. Post extraction, high-value biochemicals need to be isolated, which is achieved through a combination of one or more isolation and purification steps. The operating principles, as well as a review of isolation methods, such as membrane filtration and liquid−liquid extraction and purification using preparative chromatography, are also discussed.

The effect of zinc sulfate as a catalyst on the pyrolysis of empty fruit bunches (EFB) from oil palm was assessed. Thus, a thermo-gravimetric analyzer coupled with a Fourier transform infrared spectroscopy (TG-FTIR) was used, while the percentage of catalyst varied between 0 wt% and 3 wt% at different heating rates (10, 30, and 50 K/min). The kinetic parameters (activation energy, pre-exponential factor, and reaction order) and activation energy distribution were calculated using three kinetic models. The thermogravimetric curves for the EFB pyrolysis showed three prominent peaks in which the maximum mass loss rate was mainly due to cellulose and lignin pyrolysis. On the other hand, FTIR analysis indicated that the main gaseous products were CO2, CO, H2O, CH4, NH3, acids, and aldehydes (CH3COOH). The samples with 2 wt% of catalyst presented higher activation energies in pseudo reactions 1 and 2, ranging between 181,500 kJ/mol−184,000 kJ/mol and 165,200 kJ/mol−165,600 kJ/mol, respective... [more]

MXene has a unique two-dimensional layered structure, a large specific surface area, and good electrical conductivity, stability, magnetic properties, and mechanical properties. Attributed to its structure and properties, MXene has entered various application fields, such as tumors, antibiotics, batteries, hydrogen storage, sensors, electromagnetic shielding, etc. Studies on MXene are implemented in various fields. The preparation methods, surface functional groups, and the preparation technology of composite materials directly affect the performance of MXene and determine its application fields. As significantly important issues, many influencing factors exist in the preparation process of MXene and the process of composite material design, which directly impact the properties and applications of MXene. This paper investigates and analyzes the factors influencing the preparation, properties, and application of MXene, explores the research progress of MXene, and provides critical insig... [more]