Solute Dispersion Research Articles

Green synthesis of N-doped-carbon dots/ZnO for enhanced photocatalytic degradation of methylene blue dye: optimization of reaction parameters.

In this research work, nitrogen-doped carbon dots (N-CDs) adorned zinc oxide nanoparticles (N-CDs/ZnO) were successfully synthesized by a simple and cost-effective solution dispersion method and later on used as photocatalyst for decontamination of aqueous methylene blue (MB) dye on irradiation of UV light (300 W, 320-400nm) at room temperature. Both the N-CDs and ZnO were prepared through green technique utilizing non-toxic, inexpensive and eco-friendly precursors, namely Foeniculum vulgare and Psidium guajava leaf extract, respectively. All the synthesized samples exhibited crystalline nature with average diameter of particle 4.42nm, 12.38nm and 14.11nm corresponding to N-CDs, ZnO and N-CDs/ZnO, respectively. Further, band gap energy value (Eg) of 3.43, 2.76 and 2.49eV for N-CDs, ZnO and N-CDs/ZnO, respectively, were obtained by using Tauc's plot. The photocatalytic capability of the sample N-CDs/ZnO was compared with bare ZnO nanoparticles, utilizing identical experimental conditions. The results demonstrated that the composite exhibited notably higher photocatalytic degradation efficiency than bare ZnO nanoparticles up to 15.54%. Lower band gap value of N-CDs/ZnO was the major factor for exhibiting this behaviour, decreasing the recombination rate and thus enhancing the efficiency. Furthermore, N-CDs/ZnO exhibited 98.17% MB degradation under optimized conditions (0.03g, 5ppm, pH 10). The resultant N-CDs/ZnO exhibited good stability and decontamination efficiency up to five cycles with efficiency loss of only 7.89%. Along with, trapping experiments was conducted to analyze the role of active species involved for deep understanding of mechanism. The order of efficiency of active constituents was observed to be: •O2- > h+ > •OH. The study analyzed the non-toxic nature of treated water, revealing normal plant growth, suggesting its potential use in irrigation of parks and roadside areas. Overall, present research work obeys the green chemistry principles with the fabrication of highly efficient, eco-friendly, cost-effective photocatalyst N-CDs/ZnO by utilizing the green precursors for the whole research work.

Tailorable Fluorescent Perovskite Quantum Dots for Multiform Manufacturing via Two-Step Thiol-Ene Click Chemistry.

In practical applications, fluorescent perovskite quantum dots (PQDs) must exhibit high efficiency, stability, and processibility. So far, it remains a challenge to synthesize PQDs with stable dispersibility in tailorable monomers both before and after photocuring. In this work, a novel strategy of UV-induced two-step thiol-ene "click chemistry" is proposed to prepare PQDs with these attributes. The first step aims to epitaxially grow a shell around the PQD core to ensure stable dispersibility in a thiol-ene monomer solution. The second step is to achieve stable dispersibility in the photocured thiol-ene matrixes for multiform manufacturing processes. The tailorable PQDs (T-PQDs) not only have the highest photoluminescence quantum yield (PLQY) to ≈100% for green emission and over 96% for red emission, but also exhibit remarkable stability under severe conditions, including "double 85" aging, water exposure, and mechanical stress. Moreover, their exceptional processability allows for various processing techniques, including slot-die coating, inkjet printing, direct-laser writing, UV-light 3D printing, nanoimprinting, and spin coating. The high efficiency and stability of T-PQDs facilitate their multiform manufacturing for a wide range of applications.

Aramid nanofiber-modified carbon paper to enhance adaptability and performance of proton exchange membrane fuel cells

This study developed a novel method to enhance the comprehensive performance of carbon paper (CP) by using aramid nanofibers (ANF) modified phenol formaldehyde resin (PF). The effect of ANF modification ratios (0 wt%, 0.6 wt%, 1.2 wt%, 1.8 wt%, 2.4 wt%) on ANF dispersion in PF impregnation solution, PF thermal stability, and PF carbon matrix structure were investigated. Compared to unmodified PF, ANF-modified PF matrix carbon exhibited increasingly regular and ordered structures, with the ID/IG value decreasing from 2.16 to 2.02. Furthermore, with ANF modification ratio increasing, the tensile strength, flexural strength, porosity and gas permeability of CP exhibited a pattern of initial increase followed by a decrease, and when increasing to 1.8 %, reaching the optimal values of 14.28 MPa, 531.61 MPa, 85.94 %, and 2520 L·m−2·s−1, respectively. The limiting power density of proton exchange membrane fuel cells (PEMFCs) assembled with 1.8 wt% ANF-modified CP gradually increased with different assembly torques of 2, 4 and 6 N·m, reaching maximum values of 0.86, 0.98, and 1.1 W·cm−2, respectively. Therefore, the novel ANF modification method of CP provides new insights into enhancing PEMFCs assembly adaptability, potentially addressing issues related to low mechanical stability and poor pore structure affecting PEMFCs performance.

Hydrodynamics of a discrete conservation law

AbstractThe Riemann problem for the discrete conservation law is classified using Whitham modulation theory, a quasi‐continuum approximation, and numerical simulations. A surprisingly elaborate set of solutions to this simple discrete regularization of the inviscid Burgers' equation is obtained. In addition to discrete analogs of well‐known dispersive hydrodynamic solutions—rarefaction waves (RWs) and dispersive shock waves (DSWs)—additional unsteady solution families and finite‐time blowup are observed. Two solution types exhibit no known conservative continuum correlates: (i) a counterpropagating DSW and RW solution separated by a symmetric, stationary shock and (ii) an unsteady shock emitting two counterpropagating periodic wavetrains with the same frequency connected to a partial DSW or an RW. Another class of solutions called traveling DSWs, (iii), consists of a partial DSW connected to a traveling wave comprised of a periodic wavetrain with a rapid transition to a constant. Portions of solutions (ii) and (iii) are interpreted as shock solutions of the Whitham modulation equations.

Exploration of chemical reaction and activation energy role of Jeffery-Hamel Jeffery fluid flow in penetrable non-parallel channels with entropy optimization

Recent research has demonstrated that non-Newtonian fluids exhibit superior heat transfer capabilities compared to conventional fluids. However, current methods for enhancing heat transfer in non-Newtonian fluids have their limitations. This study aims to address these limitations by investigating the influence of chemical reactions and activation energy on heat transfer within convergent/divergent channels, as described by the Buongiorno model. The study highlights several key outcomes like Higher convergence angles lead to pronounced concentration variations and gradients, whereas divergent channels result in more uniform concentration profiles. The parameter reflecting kinetic energy dominance over thermal energy shows that increasing this parameter decreases fluid temperature due to energy conversion to kinetic form. Additionally, a higher value enhances solute dispersion and energy transfer, while entropy generation increases with higher values, indicating greater irreversibility and energy losses. These insights are crucial for optimizing channel design in non-Newtonian fluid applications, aiding in the control of concentration gradients, management of temperature variations, and overall improvement in efficiency. Numerical computations of the proposed model were performed using the BVP4c scheme.

Polymerizable fatty acid surfactant: Encapsulation of organic pigments for excellent colloidal stability in aqueous solution and water-repellent property

Organic pigments are indispensable in various applications due to their vibrant colors and durability, yet their low polarity often hinders their dispersion in an aqueous solution, leading to large aggregation and sedimentation. To address these limitations, dispersants and encapsulation techniques have been explored. In this study, nanoscale encapsulated pigments were synthesized using a novel polymerizable surfactant, sodium 11-methacrylamidoundecanoic acid (NaMAAUA), along with hydrophobic monomer of styrene or butyl methacrylate. NaMAAUA contains a pendant group of amphiphilic fatty acid, and acts as a dispersant and emulsifier, forming a copolymer shell around the pigments. The apolar tail in NaMAAUA provides hydrophobic interaction with pigments, and the polar carboxyl headgroup exposes in the water phase and enables the formation of strong hydrogen bonds with cellulose. Therefore, the resulting encapsulated pigment exhibits excellent dispersion stability, water-repellent property, washing fastness and UV resistance when applied to paper and cotton fabric, expanding the practical utility of organic pigments in an environmentally conscious manner. Characterization via various analytical techniques validates the efficacy of this approach, paving the way for enhanced pigment applications.

Effect of modified multi-walled carbon nanotubes on mechanical properties and microscopic mechanism of lithium slag geopolymers

This study aims to examine the impact of multi-walled carbon nanotubes (MWCNTs) on the mechanical properties and micro-mechanisms of lithium slag geopolymer (LSG), a novel environmentally friendly building material. Two distinct dispersion methods, which used ultrasonication or added sodium dodecyl sulfate (SDS) dispersants, were employed to disperse both pristine and modified MWCNTs. Subsequently, these dispersed MWCNT solutions were mixed with waste lithium slag and stirred to prepare LSG. Based on the experiments, it is concluded that all of these demonstrated the most significant enhancement of LSG mechanical properties at a 0.1 % mass fraction of modified MWCNTs. In comparison with the reference LSG, the compressive and bending strengths of LSG with modified MWCNTs experienced improvements of 23.29 % and 13.76 %, respectively, after a curing period of 28 days. This was also evident from a microscopic perspective. The LSGs doped with modified MWCNTs and SDS exhibited stronger Ai-O-Si and Si-O-Si vibrational bands, as well as broader N-A-S-H and C-S-H characteristic peaks compared to the pristine LSGs. The porosity of LSG samples mixed with a mass fraction of 0.1 % MWCNTs and SDS was 37.08 % lower than that of pristine LSG. FESEM electron micrographs revealed that the modified MWCNTs functioned as fillers, bridges, and extractors of cracks in the hydration products of LSG. The aforementioned results suggest that well-dispersed modified MWCNTs have a beneficial impact on the mechanical properties and microscopic characteristics of LSG.

Effect of plasma nitriding on microstructure and wear behavior of electrodeposited FeCoNiCr coating

An (FeCoNiCr)N high-entropy alloy coating with a single FCC phase was fabricated on 304 stainless steel by electrodeposition and plasma nitriding. The results indicated that the FeCoNiCr coating exhibited typical granular morphologies and a nearly equiatomic ratio of four elemental compositions. After nitriding, the coating primarily consisted of a high-entropy solid solution phase and a CrN phase, with the microstructure of the (FeCoNiCr)N coating being significantly refined due to the effect of crystallization. The microhardness of the (FeCoNiCr)N coating was 781.30 ± 20.3 HV0.5, considerably higher than that of the FeCoNiCr coating, which was 496.48 ± 21.82 HV0.5. Additionally, the (FeCoNiCr)N coating demonstrated a low friction coefficient and a wear rate of 0.59 and 6.8 × 10−8 mm3/N mm, respectively. The fine microstructure and high resistance to plastic deformation, attributed to solid solution strengthening and dispersion strengthening, were the primary factors contributing to the excellent wear performance of the (FeCoNiCr)N coating.

Unsteady solute dispersion in large arteries under periodic body acceleration

The present study investigates the effect of periodic body acceleration on solute dispersion in blood flow through large arteries. Transport coefficients (i.e., exchange, convection, and dispersion coefficients) and mean concentration of the solute are analyzed in the presence of wall absorption. The solute is quickly transported to the wall of arteries with a smaller radius, whereas the opposite is true for arteries with a larger radius. In the presence of body acceleration, the amplitude of fluctuations of the convection coefficient K1(t) increases significantly as the radius of the artery increases. In contrast, an opposite scenario exists for the dispersion coefficient K2(t). The solute dispersion process becomes more effective in arterial blood flow as the radius of the artery decreases. More interestingly, in large arteries with body acceleration, the solute is convected, dispersed, and distributed more toward the upstream direction owing to flow reversal during the diastolic phase of pressure pulsation. Note that this important feature of flow reversal is solely due to periodic body acceleration. For an artery with a small radius, under the influence of periodic body acceleration, the mean concentration of solute Cm is the minimum, and more axial spread is noticed in the axial direction. In contrast, an opposite scenario arises in the artery with a large radius. Additionally, the effect of body acceleration on the shear-induced diffusion of red blood cells is discussed in blood flow.

Dispersion of solute in a packed cylindrical tube with wall reaction

Abstract The study aims to investigate the transport of solute in a packed cylindrical tube, analytically. At the wall, the solute experiences an irreversible chemical reaction of order-one.The combined action of moments method with integral transform technique has been introduced to employ the Gill’s generalized dispersion model. The main goal is to investigate a full time evaluation of various transport coefficients in different superficial flow through porous media together with wall reaction. This study provides a perspective on how porous media influences the migration of solutes in the presence of wall reactions. Exchange coefficient is shown to be solely dependent on wall absorption. In the presence of porosity, wall absorption causes an increase in the advection coefficient's magnitudes; however, the dispersion coefficient exhibits the reverse behavior. Fluid velocity is always suppressed by damping factor, and thus advection and dispersion coefficients both controlled by damping factor. Increase in porosity parameter will reduces the axial concentration distribution. This work could have applications in areas such as groundwater flow, contaminant transport, or chemical reactions within porous materials.

Evolution of concentration distribution and removal of a solute in magnetohydrodynamics channel flow: effects of buoyancy-driven force and induced magnetic field

The dispersion of reactive solutes in various flow geometries has significant implications for ecological and environmental applications. Researchers such as Poddar et al . (Poddar et al . 2021 Proc. R. Soc. A 477 , 20200830 (doi: 10.1098/rspa.2020.0830 ) and Dhar et al . (Dhar et al . 2021 Phys. Fluids. 33 , 083609) have extensively studied solute transport in magnetohydrodynamics (MHD) channel flow, focusing on the applied magnetic field. However, the impact of the induced magnetic field on solute dispersion between two parallel plates remains poorly understood. This article presents an analytical investigation using Mei’s multi-scale homogenization approach to examine the effects of the Hartmann number, Grashof number and absorption parameter on the multi-dimensional concentration distribution and removal efficiency of a reactive solute in MHD laminar channel flow. The findings provide insights into concentration behaviour, such as the decrease in the Taylor transport coefficient with an increase in the induced magnetic field. These insights have practical implications for improving sewage and wastewater treatment by effectively separating desired particles from contaminants, contributing to advancements in environmental purification techniques.

Construction of 2-azidacetic acid functionalized high-crystallinity fluorescent covalent organic framework: Applications in mitoxantrone and Fe3+ sensing and adsorption

Due to the dual functions of fluorescence detection and adsorption, fluorescent covalent organic frameworks (COFs) have attracted significant attention. However, common fluorescent COFs often exhibit unsatisfactory fluorescence properties and selectivity, coupled with poor solution dispersibility, which limit their effectiveness in detection and adsorption applications. In response, a novel post-modified fluorescent COF (named AZC-COF) was synthesized by connecting a fluorescent COF (COF-TB) with 2-azidacetic acid through a copper-catalyzed aide-alkyne cycloaddition (CuAAC) reaction. AZC-COF demonstrated excellent solution dispersibility and robust green fluorescence, boasting an absolute fluorescence quantum yield (QY) of 7.58%, which was 13.5 times higher than that of COF-TB. Furthermore, leveraging the active carboxylic acid and triazole sites, AZC-COF exhibited remarkable binding abilities for mitoxantrone (MIX) and Fe3+, enabling sensitive detection and efficient adsorption of them. In contrast, due to the absence of these functional sites, COF-TB showed poor detection and enrichment capabilities for MIX and Fe3+. The impressive detection and adsorption efficiencies of MIX and Fe3+ in environmental water, aquatic organism (fish) and plasma samples underscore the potential of AZC-COF as a detection-adsorption platform. Additionally, AZC-COF demonstrated low toxicity and hemolytic activity, alongside promising potential for cell imaging and detection of MIX and Fe3+, highlighting its considerable application prospect in biological systems.

Hybridization of Tannic Acid With Technol PG Liposomes

Objective: This study aims to create a complex of Technol PG-based liposomes with tannic acid (TA). Method: Technol PG-based liposome using a gentle hydration method was designed, and the hybridization with TA was achieved by the interaction between the surface of Technol PG-based liposome and TA. Results: Technol PG was highly soluble in methanol and ethanol, and Technol PG-based liposome could be prepared using a gentle hydration method for the film from the ethanol dispersion. Upon addition of TA, it was hybridized with Technol PG liposome, and TA-hybridized Technol PG liposome showed high dispersibility in an aqueous solution. Conclusion: This work would provide a new type of TA-conjugated liposome-based biomaterials.

Capacitive behaviors for surface-sulfonated polyaniline nanofibers in different acidic electrolytes

Abstract Unique surface-sulfonated polyaniline nanofibers (PANI-S) were fabricated through one-pot polymerization to evaluate the feasibility of their applications as electrode materials for high-performance supercapacitors that can be operated in relatively weak acidic electrolytes. Benefiting from the self-doping effect and improved dispersion in aqueous solution for the nanofibers, as well as the effective buffering function of the electrolyte, the PANI-S exhibits excellent capacitive performance across a broad pH value range in acidic electrolytes. More clearly, the specific capacitance of the PANI-S remains remarkably stable, ranging from 752.4 to 754.4 F g−1 at a scan rate of 5 mV s−1 and from 575.4 to 536.8 F g−1 at a current density of 1 A g−1, as the pH value of the electrolyte varies from 0 to 6. However, the capacity retention rate of PANI-S gradually decreases from 79.2% to 37.2% as the current density increases from 1 A g−1 to 20 A g−1, with the pH of the buffered solution increasing from 0 to 6. The excellent electrochemical activity in low acidic electrolytes for PANI nanofibers can be attributed to the compensation effects of the self-doped local proton reservoir.

High-performance triboelectric nanogenerator with aminated barium titanate composite nanoparticles for early Parkinson’s disease diagnosis

High dielectric constant nanoparticles into polymer matrices have attracted much attention because this process can improve the nanofriction generator performance. However, the dispersion of the developed materials remains a challenge. In this paper, we present a novel high-performance nanofriction generator (FBT-TENG) based on composite nanoparticles of Amino-functionalized barium titanate and functionalized graphite oxide (FGO/ABTO) with Polyimide (PI) as substrate, which can be used as a sensor for intelligent monitoring systems. Specifically, we introduced amino groups on the surface of barium titanate to improve its dispersion in the PI solution, and the dual effect composite with functionalized graphite oxide improved the TENG performance of the PI film. Due to the FGO/ABTO synergy, the FBT-TENG can generate high output voltages, currents and power densities of 75 V, 13 µA and 4.6 W/m2, respectively, which is a 9 times increase in power density compared to the original PI film. FBT-TENG is capable of powering capacitors. In addition, the FBT-TENG can be used as a sensor to build an early Parkinson’s disease detection system, which provides a more convenient option for the early diagnosis of Parkinson’s patients and has the potential for a wide range of medical applications.

Microgravity influenced unsteady dispersion during magnetic drug targeting in an inclined tumor-stenosed microvessel with slip effects

Introduction:Recent cancer research into microgravity or altered gravity environments has gained attention for its potential to disrupt cancer cell growth and proliferation while reducing the risk of chemoresistance—a major challenge in conventional chemotherapy. Aim of the study:Motivated by the emerging applications of microgravity in cancer research, the current study aimed to mathematically investigate the potential of the microgravity-enhanced environment in combination with magnetic drug targeting (MDT) to optimize drug delivery and dispersion. Methodology:The particle velocity, including microgravity’s influence in the presence of an external applied magnetic field alongside fluid pressure, was computed analytically while the solute dispersion model was numerically evaluated using the Crank–Nicolson method. Results:Findings show that microgravity lowers particle concentration in the tumor, however, improved drug-loaded magnetic nanoparticle properties, and magnetic field strength reveal a positive impact on nanoparticle accumulation. Also, altered stenosis height, inclination angle, slip velocity, and other control parameters such as Peclet number, magnetic-tumor distance, drug source term, elimination, and local skin friction revealed significant differences in particle dispersion behavior before, within, and after the stenosis region. Conclusion:Our results suggest potential future therapeutic applications of altered gravity in combination with MDT phenomena to improve drug delivery for noninvasive therapeutic strategies.

Features of High-Precision Photothermal Analysis of Liquid Systems by Dual-Beam Thermal Lens Spectrometry.

Thermal lens spectrometry is a high-sensitivity method for measuring the optical and thermal parameters of samples of different nature. To obtain both thermal diffusivity and absorbance-based signal measurements with high accuracy and precision, it is necessary to pay attention to the factors that influence the trueness of photothermal measurements. In this study, the features of liquid objects are studied, and the influence of optical and thermal effects accompanying photothermal phenomena are investigated. Thermal lens analysis of dispersed solutions and systems with photoinduced activity is associated with a large number of side effects, the impact of which on trueness is not always possible to determine. It is necessary to take into account the physicochemical properties and optical and morphological features of the nanophase and components exhibiting photoinduced activity. The results obtained make it possible to reduce systematic and random errors in determining the thermal-diffusivity-based and absorbance-based photothermal signals for liquid objects, and also contribute to a deeper understanding of the physicochemical processes in the sample.

Construction of glycosylated zein-based colloids to simultaneously improve fucoxanthin’s thermal processing adaptability, digestive stability, and oral bioavailability

Fucoxanthin (FX) is a carotenoid found in marine environments with a range of nutritional functions. However, its application in the food industry has been restricted by its vulnerability to deterioration and absorption challenges. This study employed zein to develop hydrophilic colloids to enhance the thermal processing adaptability, gastrointestinal digestive stability, and oral bioavailability of FX. The findings demonstrated that the using glucose for the grafting modification of zein caused a deviation in its isoelectric point, reduced its water contact angle, and altered its secondary structure, resulting in higher hydrophilicity. Using glycosylated zein (GZ) for FX loading yielded homogenous, stable aqueous GZ-FX complex dispersion solutions with an encapsulation efficiency (EE) > 85.00%, a particle size < 210.00nm, a zeta-potential > -30.00mV, and a polydispersity index (PDI) < 0.30. GZ-based encapsulation notably enhanced the thermal stability of FX, retaining approximately 90.00% and 80.00% of the FX at 65 ℃ and 100 ℃, respectively. During in vitro simulated gastrointestinal digestion, GZ-encapsulation of FX demonstrated a retention increase of 30.63% and a 2.31-fold higher micellization rate. The in vivo absorption results showed that GZ-based encapsulation dramatically increased FX oral bioavailability, while its serum, liver, and kidney response levels were 51.49-fold, 5.13-fold and 6.73-fold higher. This study suggests that glycosylated alcohol-soluble proteins are highly effective carriers for delivering carotenoids, with significant application potential in the food industry.

Modeling of the separation process of a two-phase liquid in a high-temperature gas environment

Obtaining a high-quality highly dispersed salt solution can be realized from a salt solution by the method of ultrasonic exposure. As you know, concentrated salt solutions can be presented in the form of a gas-liquid medium. The influence of ultrasound, in the case of wetting a surface vibrating with an ultrasonic frequency by a thin layer, leads to the formation of a cavitation layer in the liquid layer and capillary waves on its surface, from the ridges of which, at a certain intensity of oscillations, finely dispersed aerosol droplets are detached.The detachment of droplets from the vibrating surface leads to the formation of finely dispersed salt aerosol, which saturates the heated air, which is tangentially fed into the cylindrical working chamber with further separation of hydrodynamic processes. Part of the aerosol wets the heated inner surface of the cylindrical chamber with the formation of a thin film, which gravitationally flows down the vertical solid surface and is subjected to active evaporation with the removal of the salt phase, and the second part is subjected to additional grinding and active evaporation in the central turbulent flow and centrifugal turbulent flow of hot air with additional by removing the salt phase. In order to intensify the salt removal process, the surface on which the film is formed can be profiled. Ultrasonic dispersion of the salt solution to a finely dispersed state allows to significantly increase the surface of contact with the heated air, which allows to intensify the diffusion process.

High-strength and wear-resistant Babbitt alloy coatings prepared through in-situ alloying

Babbitt alloy, a commonly used wear-resistant coating material, has a low hardness. This causes severe plastic deformation, detachment or heavy wear to easily occur under low speed and heavy-load service conditions, reducing its service life. To solve these problems and improve the bonding strength and wear resistance of the tin-based Babbitt alloy coating, a higher laser cladding power was adopted to achieve in-situ alloying of the cladding layer and enhance the strength of the coating. The increase in strength was verified through the Fleischer theory and Orowan empirical formula to mainly result from the enhancement of solid solution strengthening and dispersion strengthening. Meanwhile, due to dispersion strengthening and the presence of dendritic FeSn, the occurrence of delamination wear was effectively prevented. The bonding strength of the final sample reached 147 MPa, and the wear rate was as low as 4.24 × 10–5 mm3/N・m. Thus, a high-strength and wear-resistant Babbitt alloy cladding layer was obtained.