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Energy storage devices are the hub of a multi-energy complementary distributed energy system. Hydrated salts are the most suitable phase change material for energy storage devices, but subcooling is the main obstacle to their application. Nucleation requires a driving force so the use of nucleating agents alone does not reduce subcooling to a very low level. To address this issue, this paper first screened nucleating agents and then further reduced the subcooling of sodium acetate trihydrate in conjunction with stirring or direct current. The effects of rotor mass, rotational speed, direct current voltage, and electrode material on nucleation were analyzed. Finally, the stability of the composite phase change material in the presence of simultaneous stirring and energization was analyzed. The results showed that the addition of 1.5% in weight of disodium hydrogen phosphate dodecahydrate to sodium acetate trihydrate can reduce the subcooling to about 2.3°C. Continued addition of stirring or electricity can reduce the subcooling of sodium acetate trihydrate to within 0.5°C or even eliminate it. The higher the momentum of the stirring, the better the improvement in subcooling, phase separation, and thermal conductivity. The higher the direct current voltage, the better the nucleation effect, but the electrode life will be lower. The silver electrode has the best nucleation effect. No new material was produced in the solution after 100 cycles in the presence of both stirring and direct current. The melting point of the phase change material was increased by 0.2°C and the latent heat value decreased by 1.8%, still with good stability. The trace of deionized water should be added to the phase change material in subsequent studies to compensate for the consumption of water by the anodic elution. [ABSTRACT FROM AUTHOR]

Bacterial cellulose (BC) and chitosan (Chi) are biopolymers that play a vital role in various industrial applications due to their unique properties, such as biodegradability, biocompatibility, flexibility, and excellent physical properties. Combined, these two materials can create composites with exceptional characteristics, which can be tailored for specific applications. This study aimed to evaluate the effect of different ultrasonication and stirring treatments on the synthesis of BC/Chi composites, focusing on their chemical, physical, and mechanical properties. Based on the results of microscopy, SEM-EDS, and FTIR analysis, it was found that ultrasonication treatment provides a more effective dispersion process, resulting in higher physical and mechanical properties than BC/Chi stirring.

We study the stirring process with N − 1 species on a generic graph G = (V , E) with reservoirs. The multispecies stirring process generalizes the symmetric exclusion process, which is recovered in the case N = 2. We prove the existence of a dual process defined on an extended graph G ~ = (V ~ , E ~) which includes additional sites in V ~ ∖ V where dual particles get absorbed in the long-time limit. We thus obtain a characterization of the non-equilibrium steady state of the boundary-driven system in terms of the absorption probabilities of dual particles. The process is integrable for the case of the one-dimensional chain with two reservoirs at the boundaries and with maximally one particle per site. We compute the absorption probabilities by relying on the underlying g l (N) symmetry and the matrix product ansatz. Thus one gets a closed-formula for (long-ranged) correlations and for the non-equilibrium stationary measure. Extensions beyond this integrable set-up are also discussed. [ABSTRACT FROM AUTHOR]

Distinctive synoptic‐scale (∼1,500 km) flow features are identified within the core of the stratospheric polar‐night vortex at stratopause altitudes (∼50 km). Typically they comprise a train or a complex pattern of transient vortices, each characterized by enhanced values of potential vorticity (PV) and relative vorticity but with a weaker thermal signal. In the MERRA‐2 (and two other) reanalysis fields these cyclone‐like features persist for several days, occur episodically, and form essentially within the core of the polar‐night vortex itself. Their origin is plausibly linked to a form of barotropic instability associated with a radiatively‐induced annular ring of enhanced PV. Moreover, their ubiquity and dynamics carries possible implications for: ‐ the structure of the larger‐scale polar vortex and its preconditioning ahead of a Sudden Stratospheric Warming event; the distribution of trace‐constituents within the core; and the features representation in extended range/seasonal prediction and climate models. Plain Language Summary: In wintertime the earth's stratospheric polar vortex extends from a height of around 15 km to well above 50 km and equatorward to around 30° from the pole. At its edge, winds can be significantly in excess of 100 m s−1 whilst the vortex's core has been viewed as an enclosed containment vessel partially insulated from exterior influences. In contrast it is shown that, within the core, spatially rich patterns of synoptic‐scale (∼1,500 km) cyclone‐like features occur at stratopause altitudes (∼50 km). Their scale and structure indicates that their origin is linked to the large latitudinal temperature gradient that can develop across the polar‐night twilight zone. Their ubiquity suggests that they:‐ could contribute to the well‐mixed distribution of chemical constituents within the vortex's core; influence the overall structure of the polar vortex itself; impact upon the breakdown of the vortex during events of Sudden Stratospheric Warming; and need to be adequately represented in seasonal prediction and climate models. Key Points: Distinctive synoptic‐scale cyclone‐like features are identified within the core of the polar‐night vortex at stratopause altitudesAn account is given of their space‐time character and dynamics, and evidence adduced of their presence in three Reanalysis schemesTheir existence carries possible ramifications for seasonal and climate models and for the structure of the polar vortex itself [ABSTRACT FROM AUTHOR]

To elucidate the effect of solution viscosity on the synthesis of Ni-phyllosilicate, polyacrylamide was incorporated to create a viscous aqueous medium containing of sodium metasilicate, nickel nitrate and NH 4 F. The enhanced viscosity promotes the dispersion of the initial formed crystal seeds and the growth of Ni-phyllosilicate, culminating in a Ni-rich NiPs-RT-6 of a high Ni content of up to 55.2 wt%. Residual polyacrylamide elimination was accomplished via calcination, concurrently enhancing metal-support interaction. The as-synthesized samples display a nanoflower morphology with nanospheres overlaid with numerous thin nanosheets. The relatively small Ni particles around 5.7 nm were obtained after reduction even at a very high Ni loading, owing to its strong metal-support interaction. NiPs-RT-6 achieves a CO 2 conversion of 75.9% at 450 °C, 0.1 MPa, 60 L g−1·h−1, which closely approximates thermodynamic equilibrium. The turn over frequency for CO 2 (TOF CO2) was substantial, calculated at 3.7 × 10−3 s−1, accompanied by activation energy (E a) of 80.6 kJ·mol–1. In-situ Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) further disclosed that m -HCOO– serves as a crucial intermediate following a formate reaction pathway. With its high Ni content, finely distributed Ni particles, and strong metal-support interaction, NiPs-RT-6 demonstrates promising catalytic activity in CO 2 methanation. [Display omitted] • The room-temperature synthesis of Ni-phyllosilicate was achieved. • A viscous solvent of polyacrylamide significantly promoted the synthesis of Ni-phyllosilicate. • The reduced Ni-phyllosilicate retained small Ni particles at a high Ni content. • Polyacrylamide improved the catalytic performance of CO 2 methanation. [ABSTRACT FROM AUTHOR]

In this work, CuO mixed lemon peel dielectric is used along with the 3D printed aluminium electrodes to enhance the electrical discharge machining (EDM) performance. This work mainly focuses on improving the surface quality by optimizing the powder concentration and stirring velocity. A full factorial of 27 experiments is carried out with input parameters such as pulse off time with 3 levels (28, 58 and 98 μs), powder concentration with 3 levels (1, 2 and 3 g/L) and stirring velocity with 3 levels (900, 1800 and 2700 rpm), while keeping the current, pulse on and voltage as constant. For all trials, the output responses viz. surface roughness (SR) and material removal rate (MRR) are noted. It is evidenced that EDM performance is influenced by the stability of powder mixed dielectric. To understand the most influential input parameter and its level, analysis of variance (ANOVA) and grey relational analysis (GRA) are carried out. The output analysis exhibited that powder concentration of 2 g/L, stirring velocity of 1800 rpm and pulse off time of 28 μs as the best combination for the best quality of finish (4.72 μm) with high MRR (0.0035 g/min) than the 1 g/L PC with 900 rpm SV for the best quality finish (5.87 μm) along high MRR (0.0029 g/min) and 3 g/L PC with 2700 rpm SV for the best quality finish (5.38 μm) with high MRR (0.0030 g/min) having pulse off time of 28 μs. The experimental findings are validated with a 3D surface plot and SEM images taken on the machined surface. Also, a simulation model is built to understand the flow velocity profiles. This helps ensure the minimum stirring velocity to be maintained to enhance the stability of powder mixed dielectric.

Light emissions from cavitating liquids serve as a diagnostic tool for chemical activity, bubble collapse conditions, or excited species. Here we demonstrate the influence of mechanical stirring on sonoluminescence (SL) and sonochemiluminescence (SCL) emissions emerging in the presence of dissolved sodium salts and luminol in different sonicated liquids. In the systems investigated, driven in the 20–40 kHz range, stirring can change the spatial distribution of blue/white broadband SL emissions and of the orange sodium D-line emission, as well as their relative intensities. In many cases, an amplification of sodium emission is observed under stirring, but striking exceptions appear as well. SCL emission from luminol is mainly quenched by the mechanical agitation. The liquids under study comprise water, ethylene glycol, and phosphoric acid, all with dissolved argon or krypton, and partly xenon. From the stirring-induced changes in sonoluminescence and from high-speed video recordings, we try to draw conclusions on the actual effects of the induced rapid bulk liquid flow on the cavitating systems. Main effects seem to be enhanced gas diffusion and bubble separation or de-clustering, possibly by a separative impact of the stirring flow on populations of smaller and larger bubbles, respectively. As a consequence, large bubbles with extremely bright sonoluminescence flashes appear in phosphoric acid under stirring. Overall, a certain sensitivity of stirring effects on further system parameters has to be stated.

Chitosan-triphosphate (TPP) nanogels are widely studied drug delivery carrier systems, typically prepared via a simple mixing process. However, the effects of the processing factors on nanogel production have not been extensively explored, despite the importance of understanding and standardising such factors to allow upscaling and commercial usage. This study aims to systematically evaluate the effects of various fabrication and processing factors on the properties of nanogels using a Design of Experiment approach. Hydrodynamic size, polydispersity index (PDI), zeta potential, and encapsulation efficiency were determined as the dependent factors. The temperature, stirring rate, chitosan grade, crosslinker choice, and the interaction term between temperature and chitosan grade were found to have a significant effect on the particle size, whereas the effect of temperature and the addition rate of crosslinker on the PDI was also noteworthy. Moreover, the addition rate of the crosslinker and the volume of the reaction vessel were found to impact the encapsulation efficiency. The zeta potential of the nanogels was found to be governed by the chitosan grade. The optimal fabrication conditions for the development of medium molecular weight chitosan and TPP nanogels included the following: the addition rate for TPP solution was set at 2 mL/min, while the solution was then stirred at a temperature of 50 °C and a stirring speed of 600 rpm. The volume of the glass vial used was 28 mL, while the stirrer size was 20 mm. The second aim of the study was to evaluate the potential for scaling up the nanogels. Size and PDI were found to increase from 128 nm to 151 nm and from 0.232 to 0.267, respectively, when the volume of the reaction mixture was increased from 4 to 20 mL and other processing factors were kept unchanged. These results indicate that caution is required when scaling up as the nanogel properties may be significantly altered with an increasing production scale. [ABSTRACT FROM AUTHOR]

Bacterial cellulose (BC) and chitosan (Chi) are biopolymers that play a vital role in various industrial applications due to their unique properties, such as biodegradability, biocompatibility, flexibility, and excellent physical properties. Combined, these two materials can create composites with exceptional characteristics, which can be tailored for specific applications. This study aimed to evaluate the effect of different ultrasonication and stirring treatments on the synthesis of BC/Chi composites, focusing on their chemical, physical, and mechanical properties. Based on the results of microscopy, SEM-EDS, and FTIR analysis, it was found that ultrasonication treatment provides a more effective dispersion process, resulting in higher physical and mechanical properties than BC/Chi stirring. [ABSTRACT FROM AUTHOR]

Abstract Distinctive synoptic‐scale (∼1,500 km) flow features are identified within the core of the stratospheric polar‐night vortex at stratopause altitudes (∼50 km). Typically they comprise a train or a complex pattern of transient vortices, each characterized by enhanced values of potential vorticity (PV) and relative vorticity but with a weaker thermal signal. In the MERRA‐2 (and two other) reanalysis fields these cyclone‐like features persist for several days, occur episodically, and form essentially within the core of the polar‐night vortex itself. Their origin is plausibly linked to a form of barotropic instability associated with a radiatively‐induced annular ring of enhanced PV. Moreover, their ubiquity and dynamics carries possible implications for: ‐ the structure of the larger‐scale polar vortex and its preconditioning ahead of a Sudden Stratospheric Warming event; the distribution of trace‐constituents within the core; and the features representation in extended range/seasonal prediction and climate models.

In the wake of drawbacks of existing processes, electro chemical discharge machining (ECDM) is an evolutionary method for the micromachining of glass. However, poor flushing coupled with insufficient electrolyte replenishment and unstable temperature deteriorates the ECDM performance. Therefore, the present study is an attempt to enhance the performance by controlling the temperature and stirring rate of the electrolyte in ECDM using a magnetic stirrer that is an innovative approach, termed as S-ECDM. The voltage, electrolyte temperature, pulse-on time and electrolyte stirring rate have been considered as the process parameters. The aspect ratio (AR) and heat-affected zone (HAZ) of micro-hole have been considered as the response characteristics. The interaction of electrolyte stirring with other process parameters synergizes the energy generation and channelization behavior at optimal conditions. At optimal conditions, the AR and HAZ were found to be 0.692 and 0.404 mm2, respectively. [ABSTRACT FROM AUTHOR]

Keeping bee colonies is one of the most important sectors of investment in the global agricultural field. Internationally, beekeepers are interested in improving bee feeding methods to maximize the productivity and quality of their products. Whereas the current study aims to develop and evaluate an automatic feeding system that works with solar energy. This technique increases the vertical expansion of beekeeping by designing a multi-shelf mobile apiary for easy transportation as desired. The development process included the inclusion of automated feeders that operate electronically using sensors to provide a nutritional solution for bee colonies without human intervention. Also, the automatic apiary was provided with a sugar solution tank that was equipped with a continuous stirring system that works with a timer. Also, the automatic apiary contains an alarm system and remote mobile contact with the beekeeper in case of depletion of the sugar syrup. The variables under study included three levels of nutritional level volumes of 500, 750, and 1000 ml, respectively, with two stirring periods (3 and 6 times/day) at two concentrations for sugar solution of 50 and 67%. The evaluation process was done during the critical winter period of the year, from December to March. The main results showed that the colonies' strength had an increment ratio over control hives of 30.23% when using the highest variable levels. Also, the seasonal energy consumption ranged from 1.25–2.81 kWh per season. Therefore, beekeepers can benefit from this novel feeding approach. [ABSTRACT FROM AUTHOR]

Allantoin possesses numerous beneficial properties for the skin, like anti-irritant effects, wound healing, skin hydration, and epithelization. In this paper, we investigated a suitable preparation method for an allantoin hydrogel using the Semi-Solid Control Diagram (SSCD) method and characterized its rheological and consistency behavior. To accomplish this, xanthan gum (XG) was selected as a model gelling agent. Briefly, four hydrogels were prepared, two without allantoin (coded M01 and M02) and two with allantoin (M1 and M2). Similarly, the formulations were either prepared through magnetic stirring (M01 and M1) or homogenization in a mortar (M02 and M2). The prepared hydrogels were evaluated using the SSCD for specific parameters and indexes. The Good Quality Index (GQI) shows a higher value for the formulation, M1 = 6.27, compared to M2 = 5.45. This result is also underlined by the value of M01 = 6.45, which is higher than M02 = 6.38. Considering the consistency, the formulation M01 possessed the highest spreadability, followed by M02 and then the allantoin hydrogels M1 and M2. The rheological behavior had a thixotropic pseudoplastic flow for all the formulations. The use of SSCD pictographs outlined the rheological properties that need improvement, the method that is suitable to prepare the allantoin hydrogels, and the influence of the allantoin suspended in the XG hydrogel. [ABSTRACT FROM AUTHOR]

The article focuses on analyzing the utilization of external influences, such as metal modification, vibration, stirring the metal pool, and hot topping of steel ingots. It demonstrates the positive impact of external influences on the conditions of crystallization and solidification in various ingots. A conclusion was made that an effective approach to influencing the molding of a steel ingot can involve a combination of heating and stirring in the hot top by introducing a device into the core of the ingot, setting the liquid metal in motion. [ABSTRACT FROM AUTHOR]

This paper introduces a novel soldering method for joining aluminum foams to aluminum plates. This method uses zinc-based solder material to a rotating aluminum plate to join the aluminum foam. Rotation of the aluminum plate over the solder material drags the solder material, stirring it during the soldering process, and helps the wetting in plate-solder-foam interfaces. The mechanical properties of the joint were investigated. Excellent tensile strength was obtained compared to those samples that were welded with the soldering flux but with no rotation involved. Tensile strength was nearly 100% higher when stirring was used. The method is introduced as flux-less stir soldering (FSS). Scanning electron microscope examinations showed diffusion had occurred between the solder alloy with aluminum foam and the aluminum plate. [ABSTRACT FROM AUTHOR]

Constructing hierarchical and ultrathin‐structured metal sulfides is beneficial for achieving high‐efficiency hydrogen evolution catalysts. Herein, ZnIn2S4 (ZIS) hollow nanoflowers (HNFs) composed of ultrathin nanosheets are creatively synthesized via a facile trisodium citrate‐mediated and stirring‐assisted solvothermal method. Experimental results reveal that the synergy effect of ethanol, trisodium citrate, and continuous stirring during solvothermal synthesis process play a significant role in optimizing microstructure as well as physicochemical properties of as‐prepared ZIS samples. Importantly, the fabricated ZIS HNFs with the thinnest nanosheets (2.28 nm) manifest the highest average photocatalytic hydrogen generation rate of 301.5 μmol h−1, which is 2.3 times higher than that of the pristine ZIS microspheres composed of nanoparticles with Pt as the cocatalyst and triethanolamine (TEOA) as the sacrificial agent and outperforms most reported ZnIn2S4‐based materials under similar testing conditions. Moreover, the optimized sample also shows a hydrogen generation rate of 0.53 μmol h−1.in pure water without any cocatalyst. This controllable agitation of the reaction mixture during the hydro/solvothermal synthesis process offers an eco‐friendly and scalable approach for tuning the microstructure of nanomaterials with enhanced performance for various applications. [ABSTRACT FROM AUTHOR]

Chitosan-triphosphate (TPP) nanogels are widely studied drug delivery carrier systems, typically prepared via a simple mixing process. However, the effects of the processing factors on nanogel production have not been extensively explored, despite the importance of understanding and standardising such factors to allow upscaling and commercial usage. This study aims to systematically evaluate the effects of various fabrication and processing factors on the properties of nanogels using a Design of Experiment approach. Hydrodynamic size, polydispersity index (PDI), zeta potential, and encapsulation efficiency were determined as the dependent factors. The temperature, stirring rate, chitosan grade, crosslinker choice, and the interaction term between temperature and chitosan grade were found to have a significant effect on the particle size, whereas the effect of temperature and the addition rate of crosslinker on the PDI was also noteworthy. Moreover, the addition rate of the crosslinker and the volume of the reaction vessel were found to impact the encapsulation efficiency. The zeta potential of the nanogels was found to be governed by the chitosan grade. The optimal fabrication conditions for the development of medium molecular weight chitosan and TPP nanogels included the following: the addition rate for TPP solution was set at 2 mL/min, while the solution was then stirred at a temperature of 50 °C and a stirring speed of 600 rpm. The volume of the glass vial used was 28 mL, while the stirrer size was 20 mm. The second aim of the study was to evaluate the potential for scaling up the nanogels. Size and PDI were found to increase from 128 nm to 151 nm and from 0.232 to 0.267, respectively, when the volume of the reaction mixture was increased from 4 to 20 mL and other processing factors were kept unchanged. These results indicate that caution is required when scaling up as the nanogel properties may be significantly altered with an increasing production scale.

Mixing in a reactor can be achieved mechanically or by the injection of a gas. This can be done by injecting a gas towards the bottom of the tank. The induced flow recirculation and then the stirring quality depends on the bubbles morphology, rising velocity and frequency detachment. This study focus on the case where the stirred fluid exhibits a yield stress. It is in line with previous studies on the gas cavity at the injection point [1], the induced flow recirculation [2] and the numerical simulation [3]. Here we quantified the bubbles diameters, aspect ratios and velocities as a function of the air flow rate, rheological parameters and tank size. Scaling laws and correlations based on the characteristic dimensionless numbers governing the flow have been proposed and validated experimentally. It was found that bubble frequencies and consequently bubble volumes and velocities are mainly governed by the balance between inertial and buoyancy forces. However, viscous and yield stress effects play an important role along buoyancy and inertial in defining the bubble aspect ratios. Weakly inertial flows are characterized by elongated bubbles while high inertial flows produce almost spherical bubbles. These experimental results are of practical interest for the design of reactor or digester where yield stress fluids have to be stirred.

Constructing hierarchical and ultrathin‐structured metal sulfides is beneficial for achieving high‐efficiency hydrogen evolution catalysts. Herein, ZnIn2S4 (ZIS) hollow nanoflowers (HNFs) composed of ultrathin nanosheets are creatively synthesized via a facile trisodium citrate‐mediated and stirring‐assisted solvothermal method. Experimental results reveal that the synergy effect of ethanol, trisodium citrate, and continuous stirring during solvothermal synthesis process play a significant role in optimizing microstructure as well as physicochemical properties of as‐prepared ZIS samples. Importantly, the fabricated ZIS HNFs with the thinnest nanosheets (2.28 nm) manifest the highest average photocatalytic hydrogen generation rate of 301.5 μmol h−1, which is 2.3 times higher than that of the pristine ZIS microspheres composed of nanoparticles with Pt as the cocatalyst and triethanolamine (TEOA) as the sacrificial agent and outperforms most reported ZnIn2S4‐based materials under similar testing conditions. Moreover, the optimized sample also shows a hydrogen generation rate of 0.53 μmol h−1.in pure water without any cocatalyst. This controllable agitation of the reaction mixture during the hydro/solvothermal synthesis process offers an eco‐friendly and scalable approach for tuning the microstructure of nanomaterials with enhanced performance for various applications.

Synthesis of spirooxindole derivatives was achieved by combining Knoevenagel condensation and Michael addition between isatin, malononitrile, and dimedone or cyclohexan-1,3-dione in presence of ammonium acetate by simple stirring in ethanol at room temperature. Spirooxindole derivatives possess promising biological activities like antitumor, antifungal, antimalarial, and anti-HIV. The analytically pure spirooxindoles formed in a concise reaction time without recrystallization or column chromatography. This method is safe and avoids the use of toxic chemicals and excess consumption of energy. [ABSTRACT FROM AUTHOR]

As a reinforcement phase to form metal matrix composites, graphene has attracted more and more attention due to its excellent properties i.e. optical, electrical and mechanical properties. However, the dispersion of graphene has always been an important factor that significantly effects its development. This paper mainly summarizes the physical methods to improve the dispersion of graphene and analyzes its internal mechanism, moreover the advantages and disadvantages of these methods are depicted and compared. Finally, the improvement of the dispersion of graphene and its future applications are prospected. [ABSTRACT FROM AUTHOR]

In order to clarify the generation and decomposition characteristics of methane hydrate and its influencing factors, a high-pressure fully transparent double-reactor test platform was designed and built to conduct initial and secondary generation and decomposition tests of methane hydrate with high-purity methane and deionized water as the study objects. During the tests, the samples were stirred or not stirred to make a comparison. The experimental results showed that the hydrate generation included four stages: induction, rapid generation, slow generation and stabilization. Stirring could promote the hydrate generation. At the speed of 400 r / min, the lower reactor consumed 93. 6% more methane than the upper reactor. Meanwhile, the memory effect was more obvious, and the induction time in the secondary generation was shortened by 62. 5 %, and the methane consumption was increased by 254. 0% compared with the primary generation. There is much for reference of the study for the development of hydrate. [ABSTRACT FROM AUTHOR]

Characteristics of sand, which is a raw material of silicate and clay bricks, glass and mineral fibers, are given. Sand is a part of ceramic products used for the manufacture of refractory products. A number of means for collecting dust-forming materials are proposed. A means of transport is developed for collecting sand in a quarry. A fluidized bed drying unit for drying wet sand with detailed description of its operation is proposed. [ABSTRACT FROM AUTHOR]

In this paper, mechanical stirring and ultrasonic treatment are used to separate graphite electrode materials from copper foils in recycling spent lithium-ion batteries (LIBs). Firstly, the effects of ultrasonic power (60–180 W), ultrasonic time (1–8 min), stirring speed (420–2000 rpm), and stirring time (1–8 min) on the abscission rate of active material on copper foil were studied. It was found that the peeling-off ratio of electrode material under ultrasonic treatment was 91.34% compared with stirring treatment (84.22%). The removal of electrode material from copper foil during stirring was mainly through mechanical scrubbing. As a comparison, the generation of the microjets induced by ultrasound, the local high-temperature and high-pressure environment, and the free radicals during ultrasonic treatment are the key factors to further improve electrode material removal efficiency. An integrated ultrasound-mechanical stirrer technique can achieve a high-efficient separation performance (approximately 100% peeling-off ratio) of anode electrode materials from copper foils. The effects of mechanical stirring speed, temperature, and treatment time on the peeling-off ratios of the ultrasound-mechanical stirrer-assisted system were investigated. Finally, the results of XRF (X-ray fluorescence spectrometer), XRD (X-ray diffraction), and SEM-EDS (scanning electron microscopy coupled with energy dispersive X-ray spectroscopy) showed that the as-separated graphite electrode material had high purity and contained almost no copper foil impurities. Numerical simulation analyses briefly showed that the difference between pressure and ultrasonic temperature changes in the boundary between different anode layers (graphite on copper foil in aqueous solution) was the main effective factor in the considerable separation of graphite from copper anode foil under ultrasonic-assisted delamination. [ABSTRACT FROM AUTHOR]

Sessile droplets play a crucial role in the microreactors of biochemical samples. Acoustofluidics provide a non-contact and label-free method for manipulating particles, cells, and chemical analytes in droplets. In the present study, we propose a micro-stirring application based on acoustic swirls in sessile droplets. The acoustic swirls are formed inside the droplets by asymmetric coupling of surface acoustic waves (SAWs). With the merits of the slanted design of the interdigital electrode, the excitation position of SAWs is selective by sweeping in wide frequency ranges, allowing for the droplet position to be customized within the aperture region. We verify the reasonable existence of acoustic swirls in sessile droplets by a combination of simulations and experiments. The different periphery of the droplet meeting with SAWs will produce acoustic streaming phenomena with different intensities. The experiments demonstrate that acoustic swirls formed after SAWs encountering droplet boundaries will be more obvious. The acoustic swirls have strong stirring abilities to rapidly dissolve the yeast cell powder granules. Therefore, acoustic swirls are expected to be an effective means for rapid stirring of biomolecules and chemicals, providing a new approach to micro-stirring in biomedicine and chemistry. [ABSTRACT FROM AUTHOR]

A digital-twin-model-based optimal control system is presented for the steel continuous casting process. The system is designed for the coordinated optimization and dynamic control of secondary cooling and final electromagnetic stirring (FEMS), and involves three related parts. Firstly, a three dimensional real-time heat transfer model is established as the digital twin of the heat transfer process of continuous casting; for high accuracy, it is calibrated offline and calibrated online using measurements of the surface temperatures and shell thicknesses (only offline). Secondly, according to metallurgical rules, cooling and stirring are optimized coordinatively, based on the established digital-twin model and chaos particle swarm optimization algorithm. Thirdly, cooling and stirring are further dynamically controlled for quality stability. Finally, the system is applied in a bloom caster with model errors ≤ ±10 °C and control errors ≤ ±4 °C, which reduces the macro-segregation over grade 1.5 from 11% to 3.3%. [ABSTRACT FROM AUTHOR]

Phosphorus and ammonium can both be recovered in the presence of magnesium through struvite (MgNH4PO4·6H2O) crystallization. The present work aimed to optimize struvite crystallization at turbulent solution flow. Struvite was crystallized by magnetic stirring at different initial phosphorus concentrations between 200 and 800 mg·L−1 and high stirring rates between 100 and 700 rpm. The crystals obtained were analyzed by powder X-ray diffraction, Fourier-transform infrared spectroscopy, and scanning electron microscopy. For all experiments, the only phase detected was struvite. It was shown that for an initial phosphorus concentration of 200 mg·L−1, increasing the stirring rate to 500 rpm accelerated the precipitation of struvite, improved the phosphorus removal efficiency, and obtained larger struvite crystals. A decrease in the phosphorus removal efficiency and smaller struvite crystals were obtained at higher stirring rates. This was attributed to the solution turbulence. The limiting effect of turbulence could be overcome by enhancing the initial phosphorus concentration or by lowering the stirring rate. The highest phosphorus removal efficiency (~99%) through large struvite crystals (~400 μm in size) was obtained for an initial phosphorus concentration of 800 mg·L−1 and a stirring rate of 100 rpm. [ABSTRACT FROM AUTHOR]

Allantoin possesses numerous beneficial properties for the skin, like anti-irritant effects, wound healing, skin hydration, and epithelization. In this paper, we investigated a suitable preparation method for an allantoin hydrogel using the Semi-Solid Control Diagram (SSCD) method and characterized its rheological and consistency behavior. To accomplish this, xanthan gum (XG) was selected as a model gelling agent. Briefly, four hydrogels were prepared, two without allantoin (coded M01 and M02) and two with allantoin (M1 and M2). Similarly, the formulations were either prepared through magnetic stirring (M01 and M1) or homogenization in a mortar (M02 and M2). The prepared hydrogels were evaluated using the SSCD for specific parameters and indexes. The Good Quality Index (GQI) shows a higher value for the formulation, M1 = 6.27, compared to M2 = 5.45. This result is also underlined by the value of M01 = 6.45, which is higher than M02 = 6.38. Considering the consistency, the formulation M01 possessed the highest spreadability, followed by M02 and then the allantoin hydrogels M1 and M2. The rheological behavior had a thixotropic pseudoplastic flow for all the formulations. The use of SSCD pictographs outlined the rheological properties that need improvement, the method that is suitable to prepare the allantoin hydrogels, and the influence of the allantoin suspended in the XG hydrogel.

Xylitol is a promising phase change material for thermal energy storage at low and medium temperatures, but its supercooling and low crystallization rate can hinder its performance in actual systems. This problem can be overcome with the application of external stimuli that promotes the nucleation and subsequent crystallization of the supercooled xylitol. Seeding combined with mechanical stirring or air-bubbling, the techniques used in this study, are proven to achieve the crystallization (and the release of the stored latent heat) of xylitol, but the effect was not instantaneous. Rheological measurements were performed firstly to study the influence of shear and temperature in the crystallization of xylitol. Then, the use of different mechanisms to promote the crystallization of the material was evaluated by two different laboratory-scale prototypes; one of them included a mechanical stirring system while the other employed a gas-bubbling mechanism. Thermal power and discharged energy of xylitol were evaluated in the bubbling system prototype and the influence of supercooling in both discharged power and energy were also studied. A methodology to calculate induction time is proposed to evaluate crystallization systematically in both systems. This new systematic evaluation proposed in this work is different from that of the literature and aims to be used to compare different crystallization systems.

The 2021 Tajogaite eruption of Cumbre Vieja (La Palma, Spain) was typified by the emission of low viscosity lavas that flowed at high velocities and inundated a large area. We experimentally investigated the rheological evolution of melt feeding the eruption through concentric cylinder viscometry to understand the exceptional flowing ability of these lavas and constrain its emplacement dynamics. We conducted a set of cooling deformation experiments at different cooling rates (from 0.1 to 10 °C/min), and isothermal deformation experiments at subliquidus dwell temperatures between 1225 and 1175°C. All experiments were conducted at a shear rate of 10 s−1. Results show that disequilibrium crystallization and its timescale fundamentally control the rheological evolution of the melt, resulting in different rheological response to deformation of the crystal‐bearing magmatic suspension. Integrating rheological data with field observations allows us to shed light on the mechanisms that govern the high flowability of these lavas. Plain Language Summary: Understanding and modeling the mechanisms controlling the inundation ability of lava flows is pivotal for hazard assessment and mitigation of related risk. Lavas flowing across the Earth's surface experience different cooling conditions. These conditions are related to the thermal gradients generated at various levels within the flow's thickness. Especially for extremely fluid magmas such as those erupted at Cumbre Vieja, the different cooling paths (and different disequilibrium conditions) that lava flows experience strongly influence the crystallization processes. Both cooling and crystallization produce an increase of lava viscosity, hindering lava flowability. If crystallization occurs over timescales shorter than those of cooling, the presence of crystals may give rise to more complex flow behavior and emplacement style, including flow rupture and separation. Such conditions may favor the development of flow decoupling and lava tunnel formation. In this study we experimentally investigate the viscosity evolution of the Tajogaite lavas and the transition from pure viscous flow to more complex responses to deformation. Then, we use our data set in concert with field observation to constrain the dynamics governing the emplacement style of these lavas. Key Points: High‐T deformation experiments characterize the rheology of Cumbre Vieja lavas under both disequilibrium and equilibrium conditionsTwo different rheological responses are observed in relation to the increased disequilibrium conditions at which the melt is subjectedIntegration of experimental and field data permits to understand the mechanisms that enhance the flowing ability of these lavas [ABSTRACT FROM AUTHOR]

The recent shoot-up in demand for lightweight materials with tailored properties has increased the interest of researchers, metallurgical and materials engineers towards aluminium matrix composites (AMCs). AMCs are light and rich in properties like corrosion, strength and wear. Moreover, AMCs are among the most economical compared to their counterparts due to the low cost and availability of aluminium. AMCs are gaining employment in many engineering sectors including power, construction, automobile and aerospace. Selection of suitable base materials and compatible reinforcement is of prime importance. Therefore, in the current study, an attempt has been made to develop an effective and economical silicon carbide-reinforced AMCs through stirring-assisted squeeze casting. Mechanical, metallurgical and wear investigations were done on the developed AMCs to determine the influence of ceramic addition on the base matrix. Microstructural investigations revealed grain refinement with even dispersion of silicon carbide in aluminium matrix. The ceramic reinforcement has also led to an increase of about 62% in ultimate tensile strength and 30% in microhardness of composites over the base matrix. Improvement in properties and microstructure can be attributed to grain refinement, reduction in porosity and strengthening of the aluminium matrix by the reinforcement particles. In addition, the tribological behaviour of the fabricated composites showed significant improvement with a reduction in wear rate and friction coefficient. [ABSTRACT FROM AUTHOR]

This review provides an overview of concepts and approaches for the quantification of passive, non-reactive solute mixing in steady uniform porous media flows across scales. Mixing in porous media is the result of the interaction of spatial velocity fluctuations and diffusion or local-scale dispersion, which may lead to the homogenization of an initially segregated system. Velocity fluctuations are induced by spatial medium heterogeneities at the pore, Darcy or regional scales. Thus, mixing in porous media is a multiscale process, which depends on the medium structure and flow conditions. In the first part of the review, we discuss the interrelated processes of stirring, dispersion and mixing, and review approaches to quantify them that apply across scales. This implies concepts of hydrodynamic dispersion, approaches to quantify mixing state and mixing dynamics in terms of concentration statistics, and approaches to quantify the mechanisms of mixing. We review the characterization of stirring in terms of fluid deformation and folding and its relation with hydrodynamic dispersion. The integration of these dynamics to quantify the mechanisms of mixing is discussed in terms of lamellar mixing models. In the second part of this review, we discuss these concepts and approaches for the characterization of mixing in Poiseuille flow, and in porous media flows at the pore, Darcy and regional scales. Due to the fundamental nature of the mechanisms and processes of mixing, the concepts and approaches discussed in this review underpin the quantitative analysis of mixing phenomena in porous media flow systems in general. [ABSTRACT FROM AUTHOR]

This study proposes a purification method for aluminum alloys based on vacuum and stirring. The data shows that when the vacuum degree ranges from -10 Pa to -1000 Pa and the stirring speed of the melt varies between 30 rpm and 50 rpm, the hydrogen content in the alloy fluctuates slightly around 0.099 cm3/100g, while the oxygen content fluctuates around 24 ppm. Compared to the alloy under other processing conditions, the hydrogen and oxygen content in the alloy at this time are the lowest. Furthermore, compared to the untreated alloy, the purified alloy showed significant improvements in mechanical properties. The tensile strength and elongation of the alloy reach 200.1 ± 4.3 MPa and 0.71 % ± 0.02 %, respectively. The changes in mechanical properties are related to the decrease in hydrogen content and oxide reduction in the melt. Stirring generates bubbles in the melt, which adsorb oxides from the melt. Subsequently, vacuum causes these bubbles to expand. These expanded bubbles can rapidly absorb hydrogen in the melt. When bubbles with oxides rise to the melt surface, the melt is purified to a certain extent. Additionally, the attachment of oxides to the bubbles is observed through transmission electron microscopy. • Using computer tomography scanning to characterize the size of pores in alloys. • Investigating the purification process of molten metal under the treatment of vacuum and stirring simultaneously. • Exploring the influence of defects on the mechanical properties of alloys. [ABSTRACT FROM AUTHOR]

[Display omitted] • 78.5–103.9 µg/kg of furan was found in commercialized vegetable-based infant meals (VBIMs). • SHS-GC-Q Exactive-Orbitrap MS was validated for quantification of furan, 2-MF and 3-MF in VBIMs. • Significant mitigation of furan, 2-MF, and 3-MF was shown when VBIMs were stirred after reheating. • Four other furan derivatives were also significantly mitigated when VBIMs were stirred after reheating. • Despite mitigation by home practices of up to 69%, the risk from furan in VBIMs still cannot be ruled out. This study assessed the impact of current home practices including reheating, standing, and stirring on mitigation of furan and its derivatives in vegetable-based infant meals. Three vegetable-based infant meals (vegetables alone, with fish, with meat) underwent different home practices including reheating, post-reheating standing (60, 120 and 240 s) and post-reheating stirring (30, 60, 120 and 240 s). Targeted quantification of furan, 2-methylfuran (2-MF) and 3-methylfuran (3-MF) and exploration of additional furan derivatives were undertaken in treated and untreated vegetable-based infant meals using SHS-GC-Q Exactive-Orbitrap-MS. For the three compounds, the quality of the measurements was first validated with suitable linearity, limits of quantification, precision and recoveries. A second step highlighted high concentrations of furan (78.5–103.9 µg/kg), 2-MF (4.8–10.1 µg/kg) and 3-MF (3.4–5.8 µg/kg) in the three vegetable-based infant meals before preparation and the assessment of the cumulative risk related to these three furan compounds confirmed the relevance of studying home mitigation strategies. The third step showed that post-reheating stirring was the most effective home practice for mitigation, with maximum observed reductions of 66.3, 59.9 and 57.7 % for furan, 2-MF and 3-MF, respectively. In a fourth step, a suspect screening approach carried out on SHS-GC-Q Exactive-Orbitrap MS data revealed the presence of 2-ethyl-, 2-ethyl-5-methyl-, 2-butyl- and 2-vinyl-furan in vegetable-based meals and showed a similar mitigation trend of home practices on the relative concentrations of these four additional furan derivatives. Finally, despite a significant mitigation reaching 69 % of the furan concentration, the combined effect of home practices on furan compounds was not sufficient to rule out the risk associated with the consumption of vegetable-based infant foods and additional options are discussed. [ABSTRACT FROM AUTHOR]

[Display omitted] • Efficient zeolite synthesis from lithium extraction residue (aluminosilicate) • Exceptional sorption capacity of zeolite NaP1 from aluminosilicate residues. • Successful scale-up of synthesis of zeolite NaP. • Techno-economic viability of zeolite synthesis. • Highly profitable hydrothermal synthesis of zeolite NaP. The processing of spodumene ore for lithium extraction produces large quantities of aluminosilicate residues that need to be properly managed. This paper focuses on the scale-up feasibility and performance evaluation (i.e. zeolite properties, mass balance, operating costs) of a hydrothermal process developed to synthesize zeolite from these aluminosilicate residues. The chemical composition, ion exchange capacity and mineralogical analysis (scanning electron microscopy, X-ray diffraction) of the synthesized product were carried out. Laboratory-scale experimental results showed that the addition of stirring during the aging phase increases the ion-exchange capacity of the final product by around 36 %, and leads to a modification of the zeolite structure, while facilitating its recovery. In addition, a zeolite with a structure like NaP zeolite was produced with a very good ion exchange capacity (80 mg Ca/g). Based on the most performant conditions obtained at laboratory scale, a large-scale production process was performed. It was found that the characteristics of the zeolite produced at laboratory and scale up were quite similar, which highlighted the robustness of the proposed process. Besides, the mass balance analysis results showed that the zeolite production yield was around 94.8 % of the initial mass of aluminosilicate residues. In addition, the percentage of Al originating from the aluminosilicate residues recovered in the final zeolite is 84 %, however only 56 % of Si is recovered in zeolite. Finally, a techno-economic analysis of the zeolite synthesis process was performed using SuperPro Designer v.12 software for a plant capacity of 5 tons of aluminosilicate residues per hour and a sale value of the zeolite produced of US$ 1.00/kg. The production cost for zeolite was determined at US$ 0.62/kg. It was found that the production of zeolite from these residues proves to be economically profitable with a payback period of 4.5 years and net present value (NPV) (at 7 % interest) of US k$ 48,108. [ABSTRACT FROM AUTHOR]

Abstract The 2021 Tajogaite eruption of Cumbre Vieja (La Palma, Spain) was typified by the emission of low viscosity lavas that flowed at high velocities and inundated a large area. We experimentally investigated the rheological evolution of melt feeding the eruption through concentric cylinder viscometry to understand the exceptional flowing ability of these lavas and constrain its emplacement dynamics. We conducted a set of cooling deformation experiments at different cooling rates (from 0.1 to 10 °C/min), and isothermal deformation experiments at subliquidus dwell temperatures between 1225 and 1175°C. All experiments were conducted at a shear rate of 10 s−1. Results show that disequilibrium crystallization and its timescale fundamentally control the rheological evolution of the melt, resulting in different rheological response to deformation of the crystal‐bearing magmatic suspension. Integrating rheological data with field observations allows us to shed light on the mechanisms that govern the high flowability of these lavas.

The use of a glucose biosensor in the bioconversion processes is challenging due to a long period of intensive stirring that is required to mix the heterogenous substants together. In this work, a glucose biosensor was developed to be accurate and robust for an extended period of measuring time in agitated conditions. The sensor probe was fabricated by electro-polymerization of polyaniline (PANI) nanostructures on a gold wire before putting in gold nanoparticles (AuNPs) and carrageenan (carr) solution to make an PANI-carr-AuNPs layer. Then the probe was soaked in PQQ-Glucose dehydrogenase (GDH) solution before coating with polyurethane (PU) to prevent the enzymes from leaching away from the sensor. The sensor probe showed a sensitivity of 0.85 μA/mg/ml of glucose with R2 of 0.9973. The storage stability of the probe was up to 4 days with stable signal. In agitated condition of 150 rpm, steady signals from the sensor were continuously obtained for 72 h. In sugarcane bagasse hydrolysis with speed at 150 rpm for 72 h, the biosensor continuously displayed signals which were not significantly different in glucose concentration to the results from the HPLC method. This biosensor displayed promising applications in bioconversion processes.

Electrochemical micro-machining (ECMM) is widely used for machining small-sized components, intricate shapes, and hard materials. Fabrication of micro-holes in stainless steel 316L (SS 316L) can be effortlessly achieved by the ECMM process rather than other machining methods, owing to its favorable machining characteristics and advantages. This paper tries to elucidate the performance of ECMM on the machining of SS 316L using an eco-friendly citric acid as an electrolyte medium, and the results are compared with copper metal powder suspended in a citric acid electrolyte (suspended electrolyte) and copper metal powder suspended in a citric acid electrolyte with the assistance of a mechanical overhead stirrer (suspended electrolyte with stirrer effect). The output performance parameters such as MRR and overcut are calculated by varying the input response parameters such as machining voltage, duty cycle, and electrolyte concentration. From the experimental results at higher parameter levels, the highest MRR and moderate overcut are obtained for suspended electrolyte with stirrer effect. For suspended electrolyte, moderate MRR and the highest overcut are detected. The least MRR and reduced overcut are found for citric acid electrolyte. SEM and EDAX analysis have been carried out to see the machined micro-hole and the composition present in the specimen. [ABSTRACT FROM AUTHOR]

Uneven drying is a prominent problem in the performance of Flatbed type grain dryer. An effort to move around the materials during the drying process is needed in order to get a uniformed drying rate. This paper investigates the conditions of an evenly distributed reduction of materials' water content during drying, using a flatbed dryer and a stirring mechanization system. It is found that ≥ 4rpm stirring rotation produces a relatively even drying result after 1 hour, and that there exists a second airflow that leaked due to the stirring process moving around with the motion of the stirrer. [ABSTRACT FROM AUTHOR]

This paper describes how macroscopic stirring of a reaction mixture can be used to produce nanostructures exhibiting properties not readily achievable via other protocols. In particular, it is shown that by simply adjusting the stirring rate, a standard glutathione-based method-to date, used to produce only marginally stable fluorescent silver nanoclusters, Ag NCs-can be boosted to yield nanoclusters retaining fluorescence for unprecedented periods of over 2 years. This enhancement derives not simply from increased homogenization of the reaction mixture but mainly from an appropriately timed delivery of oxygen from above the reaction mixture. In effect, oxygen serves as a reagent that dictates size, structure, stability, and functional properties of the growing nanoobjects., (© 2024 The Author(s). Small published by Wiley‐VCH GmbH.)

The paper starts with a detailed investigation of the boundary conditions at free and fixed boundaries of any second gradient material and clarifies whether a surface tension is to be expected. The classical approach to the reaction stresses of higher gradient materials leaves a vast indeterminacy in most boundary value problems. An advanced approach is presented that yields much more definite distributions of the reaction stresses and consequently also of the surface tension. It starts from a compressible fluid the stiffness and bulk viscosity of which tend to infinity. Furthermore, the complete set of restrictions on the material parameters of linear incompressible second gradient fluids is derived from the postulate of nonnegative dissipation. Finally, a stirring process with a free surface is studied as an example. The results are based on the numerical solution of the boundary value problems of three partial differential equations of second, fourth and sixth order, respectively. [ABSTRACT FROM AUTHOR]