Solute Mass Transfer Research Articles

Revealing the intricacies of natural convection: A key factor in aqueous zinc battery design

Aqueous zinc-based batteries offer high safety, abundant resources, low cost, and environmental friendliness, making them a promising alternative to lithium-ion batteries for large-scale energy storage markets. However, the natural convection in the electrolyte during operation, which can greatly affect the battery performance, is overlooked for a long time. Through particle tracing experiments, this study demonstrates that in the vertical placement of the battery, natural convection occurs due to the variation of electrolyte density, whereas it does not happen when the cathode is on top. Besides, there is a significant difference in electrochemical performance between these two configurations, with a voltage difference of up to 0.25 V at 10 mA cm⁻² and a peak current difference of up to 3.4 mA in linear sweep voltammetry. Simulation results show that convective mass transfer can be up to 100 times greater than diffusive mass transfer in a bulk solution. This highlights the importance of considering natural convection to improve model accuracy. Further, to increase energy density, batteries are scaled up in practical applications to reduce the weight of the casing. This work simulates mass transfer conditions under various scenarios, illustrating the trade-off between current density and battery size, and offering new guidance for the design of aqueous zinc-based batteries.

Mechanistic definition and prediction of the mass exchange coefficient between rivers and hyporheic zones: The [formula omitted] of two [formula omitted]s

Solute transport in interconnected rivers and hyporheic zones is typically modeled through dual-domain models where first-order solute mass transfer between the two domains, ΩR and ΩHZ, is represented by a coefficient α. The transient storage model (TSM) is an example of such an approach. In practice, α is determined by fitting the tails of solute tracer breakthrough curves using a TSM. This approach has led to ambiguity regarding α’s physical meaning and transferability. Here, we investigated the physical basis for α and tested it with virtual experiments through the fully coupled multiphysics model hyporheicFoam for the ΩR−ΩHZ system. hyporheicFoam explicitly simulated coupled flow and solute transport over a kilometer with centimeter-scale resolution. Model results were analyzed to calculate α following its theoretical definition directly. Using the determined α within a TSM enables accurate reproduction of solute transport, underscoring α’s physical relevance and precision.

Effect of Fine Particle Content on Solution Flow and Mass Transfer of Ion-Adsorption-Type Rare Earth Ores

Fine particle content significantly affects the in situ leaching of ion-adsorption-type rare earth ores. This study investigated the effect of fine particle content on solution flow and mass transfer in leaching. The results showed that with the increase in fine particle content, the peak concentration and peak time of rare earth increased. When the fine particle content exceeded 20%, all ion-exchangeable-phase rare earth ions could be replaced with a low dosage of the leaching solution. The leachate flow rate exhibited multi-stage variation, influenced by solution permeation, ion exchange, and fluctuations in accumulated liquid height. A mass transfer analysis showed that a higher fine particle content corresponded to a smaller plate height and a larger plate number of theoretical plates. As fine particle content increased, the final rising height of capillary water decreased, with rising rates varying across different stages for the samples. Moreover, an increase in fine particle content from 5% to 20% resulted in a 94% decrease in the samples’ permeability coefficients. A mechanism analysis showed that when the fine particle content was higher, the fine particles were embedded in the gaps between coarse particles, and the ore particles in the sample were arranged continuously, resulting in a lower permeability coefficient. Then, the leaching solution could penetrate uniformly, which was beneficial for reducing leaching blind spots and improving leaching efficiency. However, excessive fine particle content might have detrimental effects. Based on these results and considering actual mining conditions, the optimal fine particle content for rare earth leaching is 20%.

Coarsening transitional kinetics of γ′ precipitates in a nickel-based single crystal superalloy during thermal exposure

The microstructural stability and coarsening kinetics of γ′ precipitates in a nickel-based single crystal superalloy (Ni-SX) were thoroughly investigated under various thermal exposure treatments. The evolutions of characteristic parameters including γ′ size, morphology, area fraction, and γ channel width were documented. Coarsening rate constants and particle size distributions (PSDs) were calculated and recorded based on measured precipitate sizes at temperatures ranging from 800 ℃ to 1100 ℃ and durations ranging from 100 h to 1010 h. The experimentally derived rate constants were compared with the calculated theoretical values from two mainstream models: matrix-controlled diffusion (LSW model) and interface-controlled diffusion (TIDC model). Notably, transitional coarsening kinetics of γ′ precipitates from the LSW model to the TIDC model was observed at high temperatures over time. Through a comprehensive consideration of key coarsening kinetics parameters such as elemental diffusivity, trans-interface diffusion coefficient, coarsening rate constant, γ/γ′ interfacial area, and solute mass transfer, the transformation of the coarsening kinetics from matrix-controlled diffusion to interface-controlled diffusion was quantitatively discussed. The emergence of the TIDC model as the dominant mechanism was attributed to relatively smaller solute mass transfer through the interface. Moreover, the degradation of γ/γ′ interfacial energy and interfacial area, coupled with the increase in solute diffusion coefficient in the matrix, facilitated the trans-interface diffusion to act as a limiting factor throughout the coarsening process.

Interfacial Instabilities During Interphase Mass Transfer of Propionic Acid

We present a numerical study of the transient two-dimensional solutal Marangoni convection which occurs at the interface of a two isothermal layers’ system made of two immiscible liquids. The solute is propionic acid and is transferred through the interface from the organic phase to the aqueous phase under gravity condition. The unsteady state of this interfacial convection problem is mathematically described by the Navier-Stokes and solute mass transfer equations in both phases. The Hele Shaw approximation was incorporated in these equations and the resulting equations were solved using the COMSOL Multiphysics software. The latter is based on the finite elements’ method. The results obtained are in good agreement with the experiments and suggest that the mass transfer rate is stronger when the acid diffusion and the instability occur together.

Clarifying sequential electron-transfer steps in single-nanoparticle electrochemical process for identifying the intrinsic activity of electrocatalyst

Single-nanoparticle collision electrochemistry (SNCE) is an effective method for determining the intrinsic activity of electrocatalysts at the single-nanoparticle (NP) level. Despite fruitful advancements in the SNCE field, determining a quantitative relationship between the NP structure and its activity has remained difficult because of an unclear understanding of SNCE. In this study, we successfully uncovered the essential roles of the sequential electron-transfer steps in the SNCE system in regulating the apparent electrocatalytic activity of single NPs. By monitoring the oxygen reduction reaction of individual Pt NPs, significantly distinct apparent activities were observed at different electrodes owing to the rate-determining step-controlled electron transfer process. Furthermore, a new theoretical model is proposed for treating the electrochemical current, which involves NP-electrode electron transfer, heterogeneous electron transfer, and mass transfer in solution as sequential steps in the SNCE system. The combination of theoretical simulations and high-resolution electrochemical measurements allows for the corresponding parameters (contact resistance, heterogeneous kinetic constants, and adsorption possibility) of sequential electron-transfer steps to be quantified, resulting in the identification of a rate-determining step for improving the intrinsic activity of electrocatalysts. This work provides a clear picture for determining the intrinsic activity of single NPs in SNCE measurements and introduces a new conceptual route for the quantification of structure-activity relationships, which ultimately guide the rational design and optimization of electrocatalytic nanomaterials.

Mass transfer of solute in an oscillating flow in a two-dimensional channel

The effective diffusion of a solute in a rectangular two-dimensional channel is experimentally studied. We experimentally examine the effective diffusion of Rhodamine B dissolved in water oscillating in a rectangular Hele–Shaw cell. The concentration of Rhodamine B in water is measured by the intensity of its fluorescence emission. In particular, we consider two problems: (i) effective diffusion of solute in water oscillating in a two-dimensional rectangular channel (Hele–Shaw cell) and (ii) effective diffusion of solute in pores between monosized hard spheres randomly packed in a rectangular Hele–Shaw cell. It is revealed that the rate of solute mass transfer exceeds the molecular diffusion rate in both cases. It has been demonstrated that when water oscillates between parallel walls, diffusion is accelerated by Taylor dispersion with the effective diffusion coefficient Deff exceeding the molecular diffusion coefficient Dm by 1–2 orders of magnitude. The effective diffusion coefficient Deff depends only on the relative amplitude but not on the frequency of the fluid oscillations in the studied range of frequencies and amplitudes. When the fluid oscillates in the pores of the porous medium, solute transport is faster than in the case of Taylor dispersion. Here, the effective diffusion coefficient depends on both the frequency and amplitude of oscillations. The analysis shows that the experimental data obtained at various frequencies and amplitudes of oscillations are consistent with the relation Deff/Dm∼Pe2 (Pe is the Peclet number). We suggest that the enhanced solute mass transfer is associated with the time-averaged fluid flows that arise due to spatial heterogeneity of the amplitude of water oscillations in the pores between randomly packed hard spheres.

Highly efficient crystallization for sustainable azeotrope separation of formic acid-Water

The cost-effective separation of azeotropes poses a shared challenge. In this work, we utilized a green technique: layer melt crystallization (LMC), to separate the formic acid and water. Characterized by the lower energy consumption and high selectivity, LMC is welcome in high-purity production preparation. Firstly, we discussed the effects of temperature, cooling and heat rates, and time on the separation performance. We discovered that temperatures were important in the solute distribution and impurity migration. Then, the stirring technique is coupled to optimize the separation performance. Under the optimal trajectory, the product purity exceeds 99.7%. Next, to better understand the crystallization process, several theoretical models are established to clarify the intrinsic correlations of process variables and target parameters. Kinetic models are established to clarify the crystal layer growth, and sweating melt flow with the temperature difference-based driving force. Interfacial solute distribution factor and mass transfer coefficient are introduced to give the solute distribution rule and impurity migration mechanisms. At last, a dimensionless number is used to evaluate the sweating intensity, and we also correlated this coefficient with the separation performance of LMC qualitatively. In conclusion, LMC provides a viable approach for separating azeotropes, and the proposed theoretical models can offer valuable support for crystallization design.

Promoting mass transfer by tri-functional carriers for high performance direct electrochemical oxidation process

Direct electrochemical oxidation process was attractive for selective and low energy consumped removal of pollutant. However, it was lengty and low efficient due to limited mass transferation by the slow two-stage mass transfer in solution and the hydrodynamic boundary layer on electrodes. Here, we introduce an innovative single-stage carrier concept to address the identified bottleneck. The carrier, comprised of magnetic biochar nanoparticles, exhibits high conductivity, magnetic separability, and strong adsorption towards 17β-estradiol. Utilizing this carrier, we were able to transfer 93.23 % of 17β-estradiol in solution to the electrodes within a significantly reduced time of 17 min, compared to 187.82 h via diffusion and 1.73 h via convection, thus demonstrating enhanced mass transfer. Furthermore, we achieved a remarkably low energy consumption of 0.11 Wh/g, a fourfold increase in the net oxidation rate, and a 70.28 % improvement in oxidation efficiency compared to processes without carrier involvement. These results underscore the significant potential of carrier usage in enhancing the performance of direct electrochemical oxidation processes by modulating mass transfer.

Rhenium extraction from dilute solution by precipitation flotation and oxidative volatilization techniques

The low mass transfer effect of dilute solution results in low recovery efficiency of critical metal Re ions from ultralow-concentration metallurgical industrial effluents. Bubble driving was an effective measure to enhance the mass transfer in the dilute solution, and bubble flotation technology was adapted to enrich and recover metal ions. In this work, the extraction of critical metal Re from dilute solutions by a precipitation flotation process was investigated. The precipitation flotation process includes ion precipitation by CTAB and ammonium salt, flocculation by PAM and air bubble flotation separation. The effects of technical parameters on Re recovery were systematically investigated. In the precipitation stage, NH4+ with a positive charge firstly reacts with the rhenate (ReO4-) with a negative charge via electrostatic action and then further reacts with CTAB to form fine CTAB(NH4ReO4) precipitate through complexation coordination. In the flocculation procedure, the particle size of precipitate flocs is elevated due to the physical polymerization of PAM polymer. In the flotation procedure, the long carbon chains on the surface of the flocs have a foaming effect due to their strong hydrophobicity, and they are trapped by the upfloated bubbles and rapidly enriched in the foams. Under the optimized conditions, the recovery efficiency of Re is 99.5% and qualified circulating water with a turbidity of 9.8 is obtained. Eventually, highly purified Re oxides (99.8%) are prepared from the Re froth product via oxidizing volatilization since the utilized organic CTAB and PAM can be burned completely during the oxidizing calcination process.

The Influence of Solvent Selection upon the Crystallizability and Nucleation Kinetics of Tolfenamic Acid Form II.

The influence of the solution environment on the solution thermodynamics, crystallizability, and nucleation of tolfenamic acid (TFA) in five different solvents (isopropanol, ethanol, methanol, toluene, and acetonitrile) is examined using an integrated workflow encompassing both experimental studies and intermolecular modeling. The solubility of TFA in isopropanol is found to be the highest, consistent with the strongest solvent-solute interactions, and a concomitantly higher than ideal solubility. The crystallizability is found to be highly dependent on the solvent type with the overall order being isopropanol < ethanol < methanol < toluene < acetonitrile with the widest solution metastable zone width in isopropanol (24.49 to 47.41 °C) and the narrowest in acetonitrile (8.23 to 16.17 °C). Nucleation is found to occur via progressive mechanism in all the solvents studied. The calculated nucleation parameters reveal a considerably higher interfacial tension and larger critical nucleus radius in the isopropanol solutions, indicating the higher energy barrier hindering nucleation and hence lowering the nucleation rate. This is supported by diffusion coefficient measurements which are lowest in isopropanol, highlighting the lower molecular diffusion in the bulk of solution compared to the other solutions. The TFA concentration and critical supersaturation at the crystallization onset is found to be directly correlated with TFA/isopropanol solutions having the highest values of solubility and critical supersaturation. Intermolecular modeling of solute-solvent interactions supports the experimental observations of the solubility and crystallizability, highlighting the importance of understanding solvent selection and solution state structure at the molecular level in directing the solubility, solute mass transfer, crystallizability, and nucleation kinetics.

An Electrochemical Immunosensor for Sensitive Detection of Cardiac Troponin I Based on the Amplification Effect of Asymmetric Bowl-Shaped Mesoporous Nanospheres

Here, a sandwich-type electrochemical immunosensor was constructed to detect cardiac troponin I (cTnI) via asymmetric bowl-shaped PdAgFe mesoporous nanospheres (PdAgFe ABMS) as signal amplification label and core–shell cubic Au/Co-LDH@ZIF-67 as substrate material. PdAgFe ABMS prepared by dual-template directional anisotropic island growth method has abundant mesoporous channels to accelerate molecular mass transfer in solution. In particular, the asymmetric bowl-like structure allows more active sites to be exposed, which improves the utilization of atoms to stabilize and high current response signals. The synergistic effect between PdAgFe increased the activation energy of the catalytic reaction and further amplified the current signal. In addition, the biosensing interface based on Au/Co-LDH@ZIF-67 not only exhibits a high electron transfer rate, but also can capture more bioactive molecules. Under the optimal conditions, the constructed immunosensor was detected to exhibit a low limit of detection (LOD, 4.47 fg ml−1) and a wide detection range (10 fg ml−1–100 ng ml−1). This work provides an accurate and convenient scheme for the clinical detection of cTnI.

Dynamics of Newtonian Liquids with Distinct Concentrations Due to Time-Varying Gravitational Acceleration and Triple Diffusive Convection: Weakly Non-Linear Stability of Heat and Mass Transfer

One of the practical methods for examining the stability and dynamical behaviour of non-linear systems is weakly non-linear stability analysis. Time-varying gravitational acceleration and triple-diffusive convection play a significant role in the formation of acceleration, inducing some dynamics in the industry. With an emphasis on the natural Rayleigh–Bernard convection, more is needed on the significance of a modulated gravitational field on the heat and mass transfer due to triple convection focusing on weakly non-linear stability analysis. The Newtonian fluid layers were heated, salted and saturated from below, causing the bottom plate’s temperature and concentration to be greater than the top plate’s. In this study, the acceleration due to gravity was assumed to be time-dependent and comprised of a constant gravity term and a time-dependent gravitational oscillation. More so, the amplitude of the modulated gravitational field was considered infinitesimal. The case in which the fluid layer is infinitely expanded in the x-direction and between two concurrent plates at z=0 and z=d was considered. The asymptotic expansion technique was used to retrieve the solution of the Ginzburg–Landau differential equation (i.e., a system of non-autonomous partial differential equations) using the software MATHEMATICA 12. Decreasing the amplitude of modulation, Lewis number, Rayleigh number and frequency of modulation has no significant effect on the Nusselt number proportional to heat-transfer rates (Nu), Sherwood number proportional to mass transfer of solute 1 (Sh1) and Sherwood number proportional to mass transfer of solute 2 (Sh2) at the initial time. The crucial Rayleigh number rises in value in the presence of a third diffusive component. The third diffusive component is essential in delaying the onset of convection.

Using 3D-printed fluidics to study the role of permeability heterogeneity on miscible density-driven convection in porous media

Miscible density-driven convection in porous media has important implications to the long-term security of geological carbon sequestration. Laboratory investigations of miscible density-driven convection in heterogeneous porous media have been greatly limited due to the challenge in constructing well-controlled heterogeneous permeability fields. In this study, three-dimensional (3D) printing was used to solve the challenge. Particularly, elementary sediment blocks were 3D printed to construct heterogeneous permeability fields having the desired mean, standard deviation, and spatial correlation length of permeability. A methanol-ethylene-glycol (MEG) solution was placed at the top of the permeability field to trigger miscible density-driven downward convection. Results showed that permeability heterogeneity caused noticeable uncertainty in the total MEG mass transferred into the permeability field, and the uncertainty increased with increasing correlation length of the permeability field. In a heterogeneous permeability field with a larger spatial correlation length, a larger effective vertical permeability is in general favorable for solute mass transfer into the underlying porous medium. Conversely, in a heterogeneous permeability field with a shorter spatial correlation length, a larger effective vertical permeability does not necessarily lead to a higher mass transfer rate. This is because mass transfer across the top boundary through miscible density-driven convection depends on the flow recirculation near the interface. A large effective vertical permeability does not necessarily lead to fast flow recirculation because the former is measured in the vertical direction whereas the latter depends more on the internally-connected, high-permeability streaks within the domain. The 3D-printed elementary sediment blocks can be re-distributed to construct another permeability field easily, which greatly reduces the experimental time and thus significantly increases the total number of experiments that can be conducted, thereby approaching the ergodicity requirement when a large number of random permeability fields is needed.

Advances in seed oil extraction using ultrasound assisted technology: A comprehensive review

AbstractThe application of ultrasonic assisted extraction to extract seed oils for multifaceted food applications is discussed in this study. Seed oils, which are notable sources of health‐promoting characteristics and reservoirs of fatty acids and phytochemicals, are being targeted for effective extraction. Conventional techniques of oil extraction, including mechanical pressing and rendering, have limitations such as low extraction rate, high energy consumption, and low yield. In this context, ultrasonic assisted extraction is green and fast oil extraction technology with a greater extraction rate and low energy consumption. Ultrasound assisted oil extraction is mostly used technique since it is environmentally friendly and can be easily integrated with other extraction processes. Ultrasound‐aided extraction uses less solvent than traditional extraction methods. In this process, cavitation bubbles form in the solvent and burst, causing changes in pressure and temperature that expedite the mass transfer of solutes into solvent. The miscella, including the solvent and oil mixture, is then desolventized using evaporators, followed by steam‐stripping to remove the extracted oil. The current review paper discusses the characteristics of ultrasonic extractions for efficient oil extraction (extraction duration, ultrasound frequency, temperature, solvent employed, and ultrasound type). The conventional and non‐conventional oil extraction methods from sources have been examined in this article, in addition to the ultrasound assisted extraction. Along with traditional and advanced oil extraction techniques, the use of ultrasonication in conjunction with other cutting‐edge techniques is covered in this article.Practical applicationsUltrasound assisted oil extraction extracts oil from vegetables, oilseeds, and nuts by using a suitable carrier. The key parameters influencing ultrasound aided extraction of oilseed include particle shape and size, moisture content of seed, amount of solvent, and extraction time/temperature. The ultimate extraction yield is influenced by the extraction time, operating frequency, operational temperature, solvent type, and proportion, and ultrasonicator design. This technique consumes less energy and requires less maintenance. It is quite efficient and reliable. On this basis, ultrasound aided extraction may be utilized commercially to increase oil extraction rate from oil seeds.

Mass Transfer Enhancement by Solution Pulsing in Laboratory Scale In-Situ Recovery

ABSTRACT Low-permeability deposits currently yield insufficient metal recovery using in-situ recovery (ISR) due to the weak interaction between lixiviant solution and the ore body as a result of low fluid flow and mineral/lixiviant contact. To improve the lixiviant/ore interaction, the use of a solution pulsing method (intermittent rather than continuous pumping) to improve the mass transfer of ions and fluid flow in such deposits could be an option. Solution pulsing alters the solution flow and mass transfer at the microscale between low- and high-permeability regions and can result in a higher overall mass transfer. This paper reports on research in which laboratory-scale solution pulsing-ISR experiments were undertaken to assess the effects of various parameters on lixiviant movement through ideal synthetic core samples. The concentration of lixiviant solution was tracked. The findings revealed that when the pump resting period was too long, the pulsed pumping was inefficient. A short pumping on-and-off time (30 min) was found to be more efficient. The results also confirmed that an increase in the hydrostatic pressure that drives the pumping increased the migration of ions. For the most effective pumping parameters, the effect of synthetic core sample permeability was also measured to confirm that a lower permeability results in a lower ion movement, as is expected from continuous pumping experiments.

Butterfly Baffle-Enhanced Solution Mixing and Mass Transfer for Improved Microalgal Growth in Double-Column Photobioreactor

Butterfly Baffle-Enhanced Solution Mixing and Mass Transfer for Improved Microalgal Growth in Double-Column Photobioreactor

Modeling mass transfer during osmodehydration of apple cubes with sucrose or apple juice concentrate solutions: Equilibrium estimation, diffusion model, and state observer‐based approach

AbstractThis article investigates the modeling aspects of mass transfer during osmodehydration of apple cubes. The obtained experimental data were fitted to three mathematical models: Azuara's equilibrium mass‐transfer model (AM), Fick's second law (FSL), and a Luenberger observer (LO). Two scenarios were considered for the mathematical modeling of mass transfer between the osmotic solution and the apple cubes. First, constant apple volume during the osmodehydration process was assumed. Then we included volume shrinkage in the dehydrated product as part of the model. The effect of the osmotic agent in the apple dehydration was also addressed by considering two different osmotic solutions, apple juice concentrate, and sucrose solutions, with different concentrations (40, 50, and 60 °Brix). The equilibrium parameters estimated with the AM model were similar to the parameters determined experimentally (p &gt; .05). The LO model accurately describes the solute mass transfer dynamics during the osmodehydration process (R2 &gt; .950). The overall findings indicate that considering the volume shrinkage as part of the model strongly influences the parameter estimation. When considering volume shrinkage in the FSL model, the estimated diffusivity parameters ranged from 1.26 to 5.05 × 10−10 m2/s for water and 0.68–19.35 × 10−10 m2/s for solutes, respectively. Not considering product shrinkage in the diffusivity model leads to overestimating both water diffusivity (29.9–76.8%) and solute diffusivity (25.3–52.8%).Practical ApplicationsOsmotic dehydration (OD) refers to a mass transfer process where solutes are transported from a hypertonic solution to a food material, while water moves from the food material towards the solution. OD improves the appearance and taste of dehydrated foods, helps inhibit the growth of dangerous microorganisms, and decreases enzymatic browning in some foods. Sucrose solutions are frequently used as osmotic solutions for food treatment in OD. An alternative to sucrose is to treat food with fruit juice concentrates. Fruit juice concentrates have low water activity and can provide bioactive compounds that enrich the dehydrated product. Understanding the effect of different factors on mass transfer during osmotic dehydration is thus critical for the efficient design, optimization, scaling‐up, and operation of OD food treatment processes. Furthermore, the proper selection of osmodehydration conditions allows us to obtain high‐quality food products with specific composition, textural/sensory properties, and microbiological characteristics. Therefore, osmotic dehydration is a food processing alternative that allows us to obtain high‐quality food products with good nutritional attributes.

The Effect of Solvent Ratio and Extraction Time on Antioxidant Activity and Flavonoid Concentration of Kedawung Leaf (Parkia Biglobosa) Through Microwave-Assisted Extraction

Kedawung (Parkia biglobosa) contains various ingredients such as alkaloids, saponins, tannins, flavonoids, and terpenoids. The flavonoid content in Kedawung is thought to have an antioxidant effect. Antioxidants are able to counteract free radicals that enter the body by donating electrons and binding them. Currently, the microwave-assisted extraction (MAE) method is widely used because the solute mass transfer from the sample matrix into the solvent is higher than the Soxhlet method. The following study aimed to know the effect of solvent ratio and extraction time on the extraction yield, flavonoid concentration, and antioxidant activity of kedawung leaf through microwave-assisted extraction. In this method, we used 40% ethanol to make the varied solute: solvent ratio such as 1:20, 1:30, 1:40, and 1:50. The extraction time used in this method was 4-7 minutes respectively. Microwave-assisted extraction has good performance to extract the active substance in Kedawung leaves. The highest yield 16.36%, total flavonoid content (57.32±2,2 mg QE/g extract), and DPPH scavenging activity (88.87±1.062%) was obtained in the extraction with a solids-solvent ratio of 1:40 g/mL, at an extraction time of 6 minutes. This method promises to take the active substance in a short time.

Deformed Vein Sets as a Record of Synmetamorphic Volume Change: Quantifying Solution Mass Transfer in Subduction‐Type Metasediments of the Del Puerto Canyon Region, Franciscan Belt, USA

AbstractThe volume change component of deformation is often ignored or assumed to be zero in tectonic studies of metamorphic belts. However, when estimating the original geometries of deformed regions, the volume change is just as important as the other two components of deformation, finite strain, and rotation. Major permanent volume change in metamorphic rocks is accomplished by solution transfer facilitated by H2O fluids and estimates of volume change can be combined with solubilities to provide required time‐integrated volumes of fluid flow. Previously applied methods for estimating rock volume change are based on absolute stretch or changes in whole‐rock chemical compositions. Estimates based on absolute stretches generally indicates large volume reductions whereas geochemical measurements generally imply limited volume change. These contrasting results exist even when the two methods are applied to the same region. In this study, we develop a largely unexplored method for estimating volume change using the direction and deformation type of deformed mineral veins. The assumptions in this method are few and appropriate uncertainties can be estimated. Application of the new method to the metagreywacke in the Del Puerto Canyon of the Franciscan belt constrains the syn‐metamorphic volume change to be greater than 7 vol.%, contrasting with previous proposals for large volume‐loss in the same region. The results of previous studies can be modified by taking into account grain rigid body rotation and grain boundary sliding. The final result of our approach yields a volume change of 7–21vol.% and implies large amounts of water‐rich fluid must have passed through the rock.