Search Results (181)

Compared with biocompatibility, osteoconductivity, and mechanical properties, the poor injectability of calcium phosphate bone cements (CPCs) is always ignored, which actually hinders the development of CPC clinical transfer in minimally invasive orthopedic surgeries. Moreover, currently, CPC preparation in the clinic is labor-intensive and requires well-trained technicists, which might also result in the unstable quality of CPCs. In this work, we focused on three research objectives: (i) introducing a standardized preparation method for CPCs; (ii) studying the effects of preparation parameters on CPC injectability and compressive strength; and (iii) studying the injecting condition effects on CPC injectability, aiming to overcome CPCs’ disadvantages in minimally invasive surgeries. Firstly, two strategies, named “variable mixing barrel control (VMBC)” and the “nested blade–baffle stirring rod (NBBSR)”, were proposed in this study to solve the problems in the preparation of CPCs, which involved blending CPC powder and an agent to generate a paste, by enhancing the mixing performance and mimicking human manual stirring actions. Secondly, although the grinding parameter could significantly generate differences in the microstructure of CPCs, the compressive strength remained relatively stable. However, it was found to significantly affect the injectability of CPCs, leading to the inefficient injection of CPCs. Finally, the effects of syringe design, dimensions, and injecting conditions on CPC injectability were studied, and the results showed that the optimization of these factors enables the injection of CPCs, which has otherwise always been infeasible to implement in minimally invasive orthopedic surgeries. Full article

This study investigates the behavior of phosphate ion transport through two structurally distinct anion-exchange membranes—AMV (homogeneous) and HC-A (heterogeneous)—in an electrodialysis system under both static and stirred conditions at varying pH levels. Chronopotentiometric and current–voltage analyses were used to investigate the influence of pH and hydrodynamics on ion transport. Under underlimiting (ohmic) conditions, the AMV membrane exhibited simultaneous transport of H₂PO₄⁻ and HPO₄²⁻ ions at neutral and mildly alkaline pH, while such behavior was not verified at acidic pH and in all cases for the HC-A membrane. Under overlimiting current conditions, AMV favored electroconvection at low pH and exhibited significant water dissociation at high pH, leading to local pH shifts and chemical equilibrium displacement at the membrane–solution interface. In contrast, the HC-A membrane operated predominantly under strong electroconvective regimes, regardless of the pH value, without evidence of water dissociation or equilibrium change phenomena. Stirring significantly impacted the electrochemical responses: it altered the chronopotentiogram profiles through the emergence of intense oscillations in membrane potential drop at overlimiting currents and modified the current–voltage behavior by increasing the limiting current density, reducing electrical resistance, and compressing the plateau region that separates ohmic and overlimiting regimes. Additionally, both membranes showed signs of NH₃ formation at the anodic-side interface under pH 7–8, associated with increased electrical resistance. These findings reveal distinct ionic transport characteristics and hydrodynamic sensitivities of the membranes, thus providing valuable insights for optimizing phosphate recovery via electrodialysis. Full article

Copper-doped indium zinc sulfides were synthesized by heating and stirring a mixture of zinc chloride, indium chloride tetrahydrate, thioacetamide, and copper chloride at 180 °C for 18 h. Among these, Zn_5.7Cu_0.3In₂S₉ exhibited a hydrogen-producing activity of 1660 μmol/g·h, which was approximately five times higher than that of pristine indium zinc sulfide. Therefore, the catalyst was characterized to investigate the effect of Cu addition. PL results revealed that the incorporation of Cu reduced the fluorescence intensity, indicating suppressed recombination of photogenerated electron–hole pairs. DRS showed that the Cu addition enhanced optical absorption in the visible-light region and narrowed the band gap. These findings suggest that the incorporation of copper into indium zinc sulfide improves its photocatalytic activity. Full article

Biodegradable magnesium-based composites show potential application in orthopedic implants, with excellent biocompatibility, low density, and biodegradable characteristics inside the human body. In this study, the stir casting procedure was employed to produce magnesium–zinc MMCs (metal matrix composites) reinforced with MgO nanoparticles, and they were characterized intensively. The analyzed compositions were Mg/4Zn, Mg/4Zn/0.4MgO, and Mg/4Zn/0.6MgO. Their mechanical properties, corrosion resistance, and microstructure were then investigated employing tensile, impact, hardness, wear, and corrosion tests, supplemented with SEM analysis. The results indicate that the Mg-4Zn-0.6MgO composite exhibited the highest performance among the tested formulations, with a tensile strength of 150 MPa, a hardness of 65 HRE (Rockwell Hardness, E-scale), and enhanced corrosion resistance. These improvements are attributed to the uniform dispersion of MgO nanoparticles and the formation of a protective Mg(OH)₂ layer, which together contribute to mechanical reinforcement and controlled degradation behavior. The combination of superior mechanical properties and customizable biodegradability verifies the engineered Mg/4Zn/0.6MgO composite as a promising candidate for a biodegradable orthopedic fixation plate without secondary surgery. Full article

Final electromagnetic stirring (F-EMS) effectively improves macrosegregation and central porosity in round bloom continuous casting, while the flow and solidification of molten steel under F-EMS have a direct impact on metallurgical properties. Fluid flow and solidification behavior in a 600 mm round bloom continuous casting process with F-EMS were simulated. The influence of the liquid fraction model on strand temperature distribution was investigated. The flow of molten steel was analyzed under both continuous and alternate stirring modes. The results indicated that in continuous stirring mode, the stirring velocity fluctuates between peaks and troughs over a specific period. The closer the F-EMS is to the meniscus, the larger the mushy zone area and the higher the stirring velocity. Due to the 10+ s rise time for current intensity, a 25 s forward and reverse stirring duration is recommended for Φ600 mm round bloom continuous casting with F-EMS. Full article

Compared with traditional immunoassay methods, microfluidic immunoassay restricts the immune response in confined microchannels, significantly reducing sample consumption and improving reaction efficiency, making it worthy of widespread application. This paper proposes an exciting multi-frequency electrothermal flow (MET) technique by applying combined standing-wave and traveling-wave voltage signals with different oscillation frequencies to a three-period quadra-phase discrete electrode array, achieving rapid immunoreaction on functionalized electrode surfaces within straight microchannels, by virtue of horizontal pumping streamlines and transverse stirring vortices induced by nonlinear electrothermal convection. Under the approximation of a small temperature rise, a linear model describing the phenomenon of MET is derived. Although the time-averaged electrothermal volume force is a simple superposition of the electrostatic body force components at the two frequencies, the electro-thermal-flow field undergoes strong mutual coupling through the dual-component time-averaged Joule heat source term, further enhancing the intensity of Maxwell–Wagner smeared structural polarization and leading to mutual influence between the standing-wave electrothermal (SWET) and traveling-wave electrothermal (TWET) effects. Through thorough numerical simulation, the optimal working frequencies for SWET and TWET are determined, and the resulting synthetic MET flow field is directly utilized for microfluidic immunoassay. MET significantly promotes the binding kinetics on functionalized electrode surface by simultaneous global electrokinetic transport along channel length direction and local chaotic stirring of antigen samples near the reaction site, compared to the situation without flow activation. The MET investigated herein satisfies the requirements for early, rapid, and precise immunoassay of test samples on-site, showing great application prospects in remote areas with limited resources. Full article

In this paper, an alternating current (AC) magnetic field-assisted device was employed to enhance the preparation process of supersonic plasma spraying coatings. The phase structure and mechanical service characteristics of the five types of coatings were tested. The research found that the porosity of the coating decreased from 3.93% to 1.58%, the hardness increased from 702.88 to 921.12 HV, the bonding strength increased from 26 MPa to 38.3 MPa, and the tribological coefficient decreased from 0.6859 to 0.4670. The mechanism is that the AC magnetic field enhances the internal structure of the coating through electromagnetic stirring, electromagnetic oscillation and other effects. It also stirs the solidification process of the powder particles, improves the melting behaviour of the coating particles at the interface, and enhances the bonding quality of the coating. The improvement of the microstructure and mechanical properties further improves the tribological properties of the coating. At the same time, it is found that the higher the intensity of the AC magnetic field is not necessarily better for the improvement of the coating performance. When the AC magnetic field voltage reaches the peak of the device, the coating formation process is disturbed by the AC magnetic field, and the coating quality formed under the same spraying process is poor. Appropriate control of the AC magnetic field can effectively improve the internal structure and service quality of the coating. This provides a new technical idea and theoretical research basis for the development of advanced equipment surface engineering protection. Full article

Dried shrimp is a popular dietary ingredient that is often included in appetizer soups, stir-fry dishes, or other stews to improve the umami taste. The effects of adding dried shrimp on the sensory characteristics and taste components of sheep bone soup were investigated through sensory evaluation and untargeted approaches. The results of the single-factor and orthogonal experiments showed that the flavor qualities of sheep bone soup were optimal under the following conditions: 30% dried shrimp added, a 1:4.5 material–water ratio, and 2.7 h of stewing time. Sensory analysis showed a significant increase in the aroma, umami, kokumi, and texture intensity of the optimized sheep bone soup with dried shrimp. The untargeted approach combined with multivariate statistical analysis showed that compounds with a sweet taste (Lys and Ser), a umami taste and umami enhancement (Ala-Leu, Glu-Pro, Glu-Glu, Asp-Phe, pyroglutamic acid, and cinnamic acid), a bitter taste (Gly-Leu, Leu-Leu, Ile-Lys, and taurine), a kokumi taste (γ-Glu-Met, γ-Glu-Leu, γ-Glu-Ile, N-acetylmethionine, and N-acetylphenylalanine), a sour taste (malic acid), and a popcorn-like aroma (2-acetylthiazole) contributed significantly to the flavor enhancement of sheep bone soup. In addition, the contribution of Ac-Ser-Asp-Lys-Pro could not be ignored. These results contribute to a better understanding and improvement of the flavor qualities of sheep bone soup. Full article

Protein crystallization is an alternative to well-established but cost-intensive and time-consuming chromatography in biotechnological processes, with protein crystallization defined as an essential unit operation for isolating proteins, e.g., active pharmaceutical ingredients. Crystalline therapeutic proteins attract interest in formulation and delivery processes of biopharmaceuticals due to the high purity, concentration, and stability of the crystalline state. Although improving protein crystallization is mainly achieved by high-throughput screening of crystallization conditions, recent studies have established a rational protein engineering approach to enhance crystallization for two homologous alcohol dehydrogenases from Lactobacillus brevis (LbADH) and Lactobacillus kefiri (LkADH). As generalizing crystallization processes across a wide range of target proteins remains challenging, this study takes a further step by applying the successful crystal contact engineering strategies for LbADH/LkADH to a non-homologous protein, an NADH-binding derivative of the Nostoc sp. PCC 1720 ene reductase (NspER1-L1,5). Here, the focus lies on introducing electrostatic interactions at crystal contacts, specifically between lysine and glutamic acid. Out of the nine tested NspER1-L1,5 mutants produced in E. coli, six crystallized, while four mutants revealed an increased propensity to crystallize in static µL-batch crystallization compared to the wild type: Q204K, Q350K, D352K, and T354K. The best-performing mutant Q204K was selected for upscaling, crystallizing faster than the wild type in a stirred batch crystallizer. Even when spiked with E. coli cell lysate, the mutant maintained increased crystallizability compared to the wild type. The results of this study highlight the potential of crystal contact engineering as a reliable tool for improving protein crystallization as an alternative to chromatography, paving the way for more efficient biotechnological downstream processing. Full article

With the rapid development of the new energy vehicle market, the demand for efficient, low-noise, low-energy consumption, high-strength, and durable gear transmission systems is continuously increasing. Therefore, it has become imperative to conduct in-depth research into the fluid heat transfer and lubrication dynamics within gearboxes. In gear systems, the interaction between fluids and solids leads to complex nonlinear heat transfer characteristics between gears and lubricants, making the development and resolution of gearbox thermodynamic models highly challenging. This paper proposes a gear lubrication heat transfer dynamics model based on LBM-LES coupling to study the dynamic laws and heat transfer characteristics of the gear lubrication process. The research results indicate that the interaction between gears and the intense shear effects caused by high speeds generate vortices, which are particularly pronounced on larger gears. The fluid mixing effect in these high vortex regions is better, achieving a more uniform heat dissipation effect. Furthermore, the flow characteristics of the lubricant are closely related to speed and temperature. Under high-temperature conditions (such as 100 °C), the diffusion range of the lubricant increases, forming a wider oil film, but its viscosity significantly decreases, leading to greater stirring losses. By optimizing the selection of lubricants and stirring parameters, the efficiency and reliability of the gear transmission system can be further improved, extending its service life. This study provides a comprehensive analytical framework for the thermodynamic characteristics of multi-stage transmission systems, clarifying the heat transfer mechanisms within the gearbox and offering new insights and theoretical foundations for future research and engineering applications in this field. Full article

Recently, intensive research has been conducted on effective and simple systems for delivering active substances deep into the epidermis, e.g., for the treatment of skin inflammation. One possibility can be the use of soluble microneedles in which active compounds are encapsulated. This article describes the preparation of modern carriers, namely microneedles with encapsulated extracts of red beet or parsley leaves, that are rich in active substances with antioxidant and anti-inflammatory properties, specifically betanin and apigenin. The concentration of hyaluronic acid sodium salt, the method of preparing the solution, and the technique of the complete filling of molds were optimized. Plant extracts were obtained with sonication or maceration. In order to characterize the extracts obtained, several techniques were employed, such as UV–Vis, LC–MS, GC–MS, and FTIR-ATR. The analyses performed allowed for confirmation of the presence of selected active substances in the extracts. The most optimal solution of the microneedles’ precursor turned out to be the one with a concentration of 10 wt.% of sodium hyaluronate, prepared by stirring and sonication. The most efficient extraction method for each plant was chosen, and the extracts were introduced into a solution of hyaluronic acid sodium salt. The resulting soluble microneedle patches can be used as an alternative to the traditional methods of delivering anti-inflammatory and antioxidant substances of plant origin. Full article

This study proposes the use of lyophilized powder of purple-fleshed sweet potato (LP) as a new multifunctional ingredient to improve the identity and quality parameters of stirred yogurts. The physical and chemical properties, color, monomeric anthocyanin content, lactic acid bacteria viability, water retention capacity, microstructure, and texture were evaluated for yogurts enriched with LP at the levels of 2% (YLP2), 4% (YLP4), and 6% (YPL6), stored for 30 days under refrigeration (4 °C). The results indicated that LP provided different intensities and shades of pink coloration to yogurt, in addition to increasing (p < 0.05) the water retention capacity and reducing the water activity. No post-acidification processes were observed during storage. YLP2, YLP4, and YLP6 showed higher stability regarding the number of viable lactic acid bacteria cells compared to the control sample (without enrichment) during storage. Interstitially, adding LP improved the microstructures of the yogurts, promoting more cross-linked networks, with greater uniformity and smaller empty zones, regardless of the level used; in addition, the yogurts (YLP4 and YLP6) were firmer and creamier. These findings demonstrate that LP can be used as a multifunctional ingredient to promote technological/functional improvements, being underscored as a promising natural colorant, stabilizer, emulsifier, and thickener for yogurts. Full article

Objectives: Cardiac magnetic resonance (CMR) plays a central role in the diagnosis and follow-up of acute myocarditis (AM). In this study, we aimed to evaluate baseline and follow-up CMR findings and associated factors in children with AM. Methods: A retrospective analysis of CMR in pediatric patients with clinical presentations suggestive of myocarditis was performed. Patients’ demographic characteristics, clinical data, and diagnostic test results, as well as CMR imaging results, were evaluated. Results: All 28 pediatric patients with acute myocarditis included in this study had late gadolinium enhancement (LGE) on initial CMR imaging. Additionally, 14 (50%) patients had increased extracellular volume (ECV), 4 (50%) patients had focal high-intensity areas on T2 STIR images, 15 (53.6%) patients had increased T1 relaxation time, and 17 (60.7%) patients had increased T2 relaxation time. At a median follow-up CMR of 6 months, 24 (85.7%) patients had LGE, 5 (17.9%) patients had increased ECV, and 7 (25%) patients had increased T1 relaxation time, while other parameters showed complete recovery. Baseline troponin and CRP levels, T1 relaxation time, T2 relaxation time, and increased ECV were found to be factors associated with the resolution of LGE. Conclusions: Baseline troponin and CRP levels, as well as T1 relaxation time, T2 relaxation time, and increased ECV, were effective parameters that seemed to predict the resolution of LGE. Larger and multicenter experiences would confirm these hypotheses. Full article

In the quest to design reactors with a higher productivity, their mixing efficiency should be highly improved. The mass transfer coefficient is a parameter that measures the rate of the refining rates and has been extensively investigated in the past; however, most of the correlations developed in steelmaking are based on the effect of the gas flow rate or its alternative form, stirring energy. The gas flow rate can play a big role in mass transfer but there are many more variables involved. This work has investigated the combined effect of five variables on the mass transfer coefficient due to bottom gas injection with two injection devices: the gas flow rate, the radial position and the separation angle of the porous plugs, the slag thickness, and the ladle aspect ratio. A novel expression in a dimensionless form has been developed, which accurately predicts the mass transfer coefficient. The expression proposed indicates that increasing the gas flow rate, the slag thickness, the ladle aspect ratio, and the separation angle also increases the mass transfer coefficient. On the contrary, increasing the radial position away from the center affects mass transfer, especially at high gas flow rates. Based on the experimental data and their practical application, an optimum layout for the injection of gas is suggested to optimize both mass transfer and the mixing intensity of liquid steel. Full article

Butt welding experiments on 6061 Al alloy and Q235B steel of 2 mm thickness were conducted using an ER4047F flux-cored wire as the filler metal, after adding a pulsed magnetic field into the process of cold metal transfer (CMT) welding. The effect of the pulsed magnetic field intensity on the macro morphology, microstructure, tensile strength and corrosion resistance of the welding–brazing joint was analyzed. The results showed that when the pulsed magnetic field intensity increased from 0 to 60 mT, the wettability and spreadability of the liquid metal were improved. As a result, the appearance of the Al alloy/steel joint was nice. However, when the pulsed magnetic field intensity was 80 mT, the stability of the arc and the forming quality of the joint decreased, which resulted in a deterioration in the appearance of the joint. A pulsed magnetic field with different intensities did not alter the microstructure of the joint. All of the joint was composed of θ-Fe₂(Al,Si)₅ and τ₅-Al_7.2Fe_1.8Si at the interface and Al-Si eutectic phase and α-Al solid solution at the weld seam zone. Actually, with the pulsed magnetic field intensity increasing from 0 mT to 60 mT, the IMC thickness in the interfacial layer gradually reduced under the action of electromagnetic stirring. Also, the grain in the weld seam was refined, and elements were distributed uniformly. But when the pulsed magnetic field intensity was 80 mT, the grain in the weld seam began to coarsen, and the intermetallic compound (IMC) thickness was too small, which was unfavorable for the metallurgical bonding of Al alloy and steel. Therefore, with the increase in pulsed magnetic field intensity, the tensile strength of the joints first increased and then decreased, and it reached its maximum of 187.7 MPa with a pulsed magnetic field intensity of 60 mT. Similarly, the corrosion resistance of the joint first increased and then decreased, and it was best when the pulse magnetic field intensity was 60 mT. The Nyquist plot and Bode plot confirmed this result. The addition of a pulsed magnetic field caused less fluctuation in the anode current density, resulting in less localized corrosion of the joint using the scanning vibrating electrode technique (SVET). The XPS analysis showed the Al-Fe-Si compounds replacing the Fe-Al compounds in the joint was the main reason for improving its corrosion resistance under the action of a pulsed magnetic field. Full article