Mixing Time Research Articles

Diseño de un sistema de agitación para un biorreactor de 1m3 de capacidad para la producción de ácido glicérico a partir de glicerol por fermentación microbiana de Acetobacter tropicalis

This work presents the design of an agitation system for a 1m3 capacity bioreactor intended to produce glyceric acid (GA) through microbial fermentation of A. tropicalis using 20% v/v glycerol as the primary substrate. Building on previous studies that evaluated ideal conditions for glyceric acid production, initial data were utilized to identify the impeller type and perform subsequent calculations, including impeller Reynolds number, power consumption, and mixing time. Once the agitator type was specified, standard geometric relationships were employed to size components of the agitation system, such as tank size, baffle plates, and agitator dimensions. Power consumption calculations were compared with results from other studies on fermentation media with similar rheological characteristics. The agitator's power consumption for mixing 1m3 of medium was determined to be 8.35 kW, achieving 95% homogenization in 5.14 seconds, with a mixing time error of approximately 10%, operating at an agitation speed of 500 rpm. Keywords: agitation system; glyceryc acid; bioreactor

Can a gradual weaning and separation process reduce weaning distress in dam-reared dairy calves? A comparison with the 2-step method

The weaning and separation phase remains one of the biggest challenges for cow-calf-contact systems, but a gradual process that better mimics the naturally occurring reduction in milk intake has not yet been scientifically investigated. Therefore, the aim of our study was to compare behavioral and physiological indicators of distress in 3 mo-old dam-reared dairy calves (with previous full-time cow-calf contact) weaned and separated either via gradual reduction of contact time with the dam (GR, 1 week half day contact, 1 week morning contact, 1 week fence-line contact before complete separation, n = 18) or via 2-step weaning using a nose flap (NF, 2 weeks access to dam with a nose flap, 1 week fence-line contact before complete separation, n = 18). Behavior was recorded 1 week before (or for lying 3 weeks before) weaning start and during the 3 week weaning and separation period with direct observations on 4 d per week or via accelerometers (locomotor play, lying behavior). Blood and fecal samples were taken twice per week from weaning start until 3 weeks after weaning start. Calves were weighed weekly. Statistical analysis was conducted using (generalized) linear mixed models. Over the whole weaning and separation phase, NF calves showed a stronger decrease in the number of lying bouts, amount of locomotor play and average daily weight gains, as well as a higher increase in total mixed ration feeding time compared with GR calves, whereas GR calves vocalized more often and showed more searching behavior than NF calves. Also, the neutrophil:lymphocyte ratio of NF calves was elevated on d 3 after insertion of the nose flaps compared with baseline, but showed no change for GR calves on any sampling day. Overall, results point toward a favorable effect of a gradual weaning strategy on reduction of weaning and separation distress in dam-reared dairy calves, but the method requires further improvement from the protocol used in our study.

Development of high-volume fly ash concrete with improved interfacial transition zone

The interfacial transition zone (ITZ) is a vulnerable region in concrete, particularly in high-volume fly ash (HVFA) concrete where a significant portion of fly ash particles remain unreacted. In order to improve the ITZ of HVFA concrete, this work introduces a novel approach by targeted employing slag in the ITZ. Slag-modified cement paste was used to coat coarse aggregate, which was further mixed with other materials to cast HVFA concrete. Various parameters during preparing the coated coarse aggregate, such as the water-to-cementitious material ratio of the cement paste, the slag content in cementitious materials, the mass ratio of coarse aggregate to cement paste, the mixing time of coarse aggregate and cement paste, and the drying time after mixing, were investigated to uncover their influence on the porosity of the ITZ in HVFA concrete. By using the optimized values of these variables of 0.35, 3.8%, 3.2, 10 min and 1 h, respectively, it is feasible to achieve ITZ in HVFA concrete characterized by a porosity of 23.6% and refined pore structure, alongside enhanced compressive strength of the concrete.

Optimization of isolated intersection signal timing and trajectory planning under mixed traffic environment: The flexible catalysis of connected and automated vehicles

With the development of connected and automated vehicles (CAVs) enables real-time interaction between intersection signals and vehicle trajectories. The full use of this technological breakthrough will help traffic managers improve the performance of intersections. Most previous research focuses on the 100% CAV environment and the single lateral or longitudinal optimization of CAVs. Based on the flexible characteristics of CAVs, this paper proposes that CAV is regarded as the catalyst of vehicle platoon in mixed traffic environment and considers the uncertainty of CAVs and CHVs’ interaction in the real-world, which can promote the generation of controllable platoon through the “catalytic” mode of cooperative, accelerated, or direct lane-changing, and cooperative or direct overtaking. Simultaneously, a two-stage optimization model of mixed traffic trajectory and signal timing is proposed. Stage I: Based on the predicted vehicle platoon information, a dynamic NEMA signal timing scheme without duplicate structures is generated to minimize vehicle delays. Stage II: Based on the timing scheme, the generation of controllable and stable platoon and vehicle trajectory optimization model are established to minimize vehicle emissions. Dynamic programming with NEMA signal groups as sub-states is designed to solve the proposed model. The performance of the proposed model under different scenarios is investigated through numerical experiments and compared with benchmark models. Results show that the proposed model will outperform the benchmark models regarding average vehicle delay and emission under more realistic traffic demands. The average vehicle delay can be reduced by 54.32% and 7.33%, and the average vehicle emissions can be reduced by 19.1% and 0.8%, respectively. Meanwhile, the sensitivity analysis of CAV market penetration shows that the proposed model can perform satisfactorily at 20% CAV market penetration. Notedly, with increased market penetration, the proposed model will obtain better performance.

Novel alkaline solid reagent for the preparation of one-part metakaolin-based geopolymers

In recent years, there has been a growing interest in one-part geopolymers due to their simplified preparation process, which involves adding water instead of highly alkaline and corrosive solutions. This study aimed to synthesize a solid reagent (SR) based on NaOH and colloidal silica and investigate its impact on the processing stages and resulting physico-mechanical properties of one-part geopolymers based on metakaolin. After curing the samples at 40 °C, various properties, including elastic modulus, cold crushing strength, apparent porosity, and density, were evaluated. Optimal results were achieved with a mixing time of 20 min and a formulation containing 50 % by weight of SR. Under these conditions, the cured samples exhibited an elastic modulus of 8.2 GPa, a crushing strength of 14.04 MPa, an apparent porosity of 16 %, and a density of 1.51 g/cm3 after one day. These findings highlight the potential application of the developed solid reagent in the design of geopolymers for thermal and acoustic insulation in modern construction projects.

Characterization of Fluoroacrylate Palm Oil Polyurethane (FPOPU) with Different Synthesis Methods Using Fourier-Transform Infra-Red (FTIR)

In this study, fluoroacrylate palm oil polyurethane (FPOPU) was synthesized with different synthesis methods. FPOPU was synthesized stepwise starting with the synthesis of acrylated epoxidized palm oil (AEPO) by a reaction of acrylic acid (AA) and triethylamine (TEA) as the catalyst. Then, palm oil polyurethane (POPU) was formed by the reaction of AEPO with isophorone diisocyanate (IPDI) and hydroxyethyl acrylate (HEA) as an end cap agent. POPU was further added with 1,6 hexanediol diacrylate (HDDA), trimethyloltripropane triacrylate (TMPTA), and heptafluorodecyl methyl-metacrylate (HDFDMA) monomers to form FPOPU. FPOPU synthesis methods were studied by manipulating the sequence of chemicals added, temperature, and mixing time of POPU. The FPOPU mixture was finally cast onto a silicone mold with 1 mm thickness and cured under UV radiation at 120 seconds. Based on the analysis, pre-mixed IPDI with HEA at 60°C for 15 min followed by the addition of AEPO at 60°C and further mixed for 3 hours (Method 2) shows the complete formation of the urethane chain. It is proven by the existence of NH peak at 3500 cm-1 and the disappearance of NCO peak at the range of 2200-2500 cm-1 indicating the NCO functional group has completely reacted with OH group in AEPO. The addition of fluorination also can be proved by the existence of CF stretching at 1012 cm-1. This study provides information regarding comparison between the synthesis method of FPOPU.

Cultivation Of Spirulina Platensis for carbon dioxide bio sequestration in hybrid photobioreactor with real-time monitoring system

Innovative methods for effectively sequestering significant amounts of carbon dioxide (CO2) are required to address the ongoing problem of greenhouse gas emissions, which have increased in tandem with industrial development. Optimisation of the performance of the photobioreactor remains a challenge, despite the potential of using photobioreactors and cyanobacteria for bio sequestration. A potential solution lies in the development of a hybrid photobioreactor design. Thus, this study aims to develop a hybrid design of the photobioreactor equipped with tailor-made real-time monitoring system known as FCB2022 for cultivating Spirulina platensis. The performance is evaluated by monitoring real-time data such as pH, dissolved oxygen (DO), and temperature, alongside assessing the growth kinetic of cyanobacterium, CO2 sequestration, oxygen release rate and mass carbon balance. These assessments are conducted under varying photon flux densities (PFD) of 100µmol/ (m2.s), 200µmol/ (m2.s), and 300µmol/ (m2.s). The result demonstrates that FCB2022 exhibited high hydrodynamic performance with parameters like mixing time, circulation time, Reynold number, and empty bed residence time showing favourable values. The optimal ranges for temperature, pH, and dissolved oxygen are determined to be between 23.56 and 29.11 ⁰C, 9.03–9.58, and 6.57–6.89 mgO2/L, respectively. Under the conditions of 15% CO2 and PFD of 300µmol/ (m2.s), the specific growth rates reach 0.36±0.004 /day and maximum biomass concentration attains 1.52±0.03 kg/m3. Notably, the PFD of 300µmol/ (m2.s) yields the highest conversion of carbon into biomass, ranging from 1.09×10−02 kg to 1.26×10−02 kg, representing the yield of 31–83% in each CO2 injection treatment.

Glu-A3b allelinin rekombinant kendilenmiş hat popülasyonunda ekmeklik buğdayın gluten kalitesi üzerinde önemli bir etkisi vardır

In this study, a total of 147 wheat lines with variying low molecular weight glutenin subunits (LMW-GS), obtained by crossing Tosunbey and Tahirova2000 bread wheats, were included. Milling, protein, dough-mixing properties of the genotypes were measured and their relations with LMW-GS were investigated in eight different environments. As the LMW-GS of the parents were quite different; milling, protein and dough-mixing properties of the lines were significantly influenced. In this regard, presence of rye translocation (Glu-B3j) reduced flour yield and increased damaged starch and protein contents. In terms of protein quality, Glu-A3b+Glu-B3b allellic combinations were better than GluA3b+Glu-B3j or Glu-A3e +Glu-B3j allellic combinations. It was observed that negative effects of rye translocation could be minimized by selecting proper Glu-3 alleles, such as Glu-A3b instead of Glu-A3e. LMW-GS combinations of the lines influenced mixolab mixing and thermorheological properties. In this respect, the lines with Glu-A3b or Glu-B3b allelles showed increased mixing time and stability as compared to the lines with Glu-A3e or Glu-B3j allelles. The effect of LMW-GS alleles on gluten quality and dough strength was statistically bb > eb > bj > ej. In terms of myxolab stability value related to bread volume; 1 = 2*, 7 + 9 > 17 +18, b > e and b > j; in terms of mixing time; 1 > 2*, 7 + 9 < 17 +18, b > e and b > j. As a result, the Glu-A3b allele can be used to increase gluten quality, and the Glu-B3j allele can be used to increase protein content. Proper allellic combinations of LMW-GS in wheat can be developed for a given bakery product.

Study on the development and performance optimization of gussasphalt containing high percent of fine reclaimed asphalt pavement

Currently, the utilization rate of fine reclaimed asphalt pavement (FRAP) in hot recycled asphalt mixtures is low. Therefore, this study focuses on the development and performance optimization of recycled gussasphalt (RGA) with a FRAP content of 38.5%. The total content of reclaimed asphalt pavement (RAP) is 50%. The impact of various factors on the pavement performance of RGA, including modifier dosage, asphalt content, type of asphalt, rejuvenating agent, mixing time, and RAP preheating temperature was analyzed. The results show that RGA has good workability and fatigue resistance. Its high- and low-temperature performance meets the requirements of the Chinese specification for gussasphalt, but it is still slightly inferior to gussasphalt made from virgin materials. Increasing the preheating temperature of RAP and extending the mixing time of RGA can enhance the performance of RGA. But excessive increases will cause asphalt aging, which negatively affects RGA's low-temperature performance and fluidity. More attention should be given to improving the low-temperature performance of RGA, which can be improved by selecting asphalt with better resistance to aging or by incorporating a rejuvenating agent. RGA offers significant economic benefits, with a cost reduction of approximately 27% compared to GA.

Enhancing the efficiency of metals extraction from waste lithium-ion batteries through glycine leaching using response surface methodology for economic feasibility

Recycling of lithium-ion batteries (LiBs) has captured remarkable interest due to its potential to mitigate pollution and conserve natural resources and energy. This study is establishing an environment friendly method for metals leaching from LiBs utilizing glycine (NH2CH2COOH) as a leaching agent. Li dissolution is being investigated as a function of time, pulp density, glycine concentration, and temperature. The results are evincing the leaching of Li (around 94%) using 2 M glycine at 75 °C temperature, 50 g/L pulp density and 120 min mixing time. Response surface methodology (RSM) techniques are being employed to enhance the standard hydrometallurgical process. The kinetics of Li leaching are well fitted with the “chemical reaction-controlled process” equation of the shrinking core model (1 - (1 - x) 1/3 = kt) and the energy of activation is found to be 23.69 kJ/mol. Moreover, the economic evaluation of the leaching process reveals that at optimum conditions, the average profit response for treated metals is 2394.56 USD per tonne of black powder. Therefore, the use of glycine as a green extractant not only augmenting the leaching efficiency but also minimizing the usage of inorganic acids, proffering a better alternative for green recovery of waste LiBs in future.

Quantifying the bitter masking effect of drug-cyclodextrin complexation: NMR-ROESY mixing time approach

Taste, especially unpleasant taste, can be key for patient compliance. In the formulation development process, drug-cyclodextrin (CD) inclusion complexes are often used to improve the solubility of a drug and/or mask its bitterness. This study aimed to evaluate the bitter masking effect of CDs on different drugs using NMR-ROESY analysis, human sensory tests, and e-tongue measurements. The strength of inclusion complex formation between drugs and CDs was investigated by NMR-ROSEY, and these results were compared to human sensory test results. In the sensory test, participants identified which drug-CD inclusion complexes were not bitter. NMR-ROSEY results aligned with the sensory tests; short magnetization transfer times corresponded to masked bitterness. The electrical tongue was not able to detect the taste of any of the drug-CD inclusion complexes. Additionally, we used NMR-ROSEY to determine which drug-CD inclusion complex formed in a system with multiple drug substances present. This research offers valuable insights into the bitter masking effect of CDs on different drugs and presents a comprehensive evaluation approach using various methods. This knowledge has significant implications for the pharmaceutical industry, clinical practice, and patient care, contributing to improved patient compliance and satisfaction with bitter medications.

Effect of Gas Distribution Mode on Bath Stirring and Mixing in a Bottom‐Blown Converter

Currently, converter steelmaking is the main method for steelmaking, the performance of bottom blowing and bath stirring would obviously affect the efficient and stable smelting of high‐quality clean steel. At present, the uniform bottom gas distribution mode is mostly applied in converter steelmaking, which would probably lead to unstable stirring performance and inadequate mixing at the later stage of furnace campaign. Therefore, a nonuniform bottom gas distribution mode is proposed herein, which intends to improve the mixing efficiency. The physical and numerical simulations are carried out to investigate the influence of gas flowrate, nozzle configurations, and bottom gas distribution mode on bath stirring and mixing. In the results, it is shown that the large and asymmetric circulation flow is formed due to the nonuniform gas distribution for each nozzle, which enhances stirring in the horizontal direction and ultimately improves mixing efficiency. Compared with the uniform gas distribution mode, when gas distribution ratio of nonuniform bottom blowing is 3:1, the mixing time is reduced by 29%, the average velocity of liquid steel is increased from 0.0342 to 0.0404 m s−1, the ratio of the dead zone is decreased by 26.23%, and the proportion of active flow region is added by 10.49%.

Mixing time of random walk on dynamical random cluster

We study the mixing time of a random walker who moves inside a dynamical random cluster model on the d-dimensional torus of side-length n. In this model, edges switch at rate μ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\mu $$\\end{document} between open and closed, following a Glauber dynamics for the random cluster model with parameters p, q. At the same time, the walker jumps at rate 1 as a simple random walk on the torus, but is only allowed to traverse open edges. We show that for small enough p the mixing time of the random walker is of order n2/μ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$n^2/\\mu $$\\end{document}. In our proof we construct a non-Markovian coupling through a multi-scale analysis of the environment, which we believe could be more widely applicable.

Using spherical harmonics to solve the Boltzmann equation: an operator-based approach

ABSTRACT The transport of charged particles or photons in a scattering medium can be modelled with a Boltzmann equation. The mathematical treatment for scattering in such scenarios is often simplified if evaluated in a frame where the scattering centres are, on average, at rest. It is common therefore to use a mixed coordinate system, wherein space and time are measured in a fixed inertial frame, while momenta are measured in a ‘co-moving’ frame. To facilitate analytical and numerical solutions, the momentum dependence of the phase-space density may be expanded as a series of spherical harmonics, typically truncated at low order. A method for deriving the system of equations for the expansion coefficients of the spherical harmonics to arbitrary order is presented in the limit of isotropic, small-angle scattering. The method of derivation takes advantage of operators acting on the space of spherical harmonics. The matrix representations of these operators are employed to compute the system of equations. The computation of matrix representations is detailed and subsequently simplified with the aid of rotations of the coordinate system. The eigenvalues and eigenvectors of the matrix representations are investigated to prepare the application of standard numerical techniques, e.g. the finite volume method or the discontinuous Galerkin method, to solve the system.

Activated carbon treated with different chemical agents for pertechnetate adsorption

The study investigated the adsorption behaviour of different activated carbon samples for pertechnetate under diverse conditions. Characterizations of A-CF-F and A-CF-Z samples were done using BET, FTIR, XRD, XRF and SEM–EDX methods. In batch experiments, maximum adsorption occured at pH 2, with a swift process and an optimal phase mixing time determined as 1 h for all of the samples. Analyzing experimental data using Langmuir and Freundlich adsorption models revealed coefficients of determination R2 exceeding 90%. The Freundlich isotherm was found to be more suitable for describing the adsorption process.

Nano‐Calcium Carbonate with Core–Shell Structure was Prepared by Dopamine Chelation Using Pluronic F‐127 as Template

AbstractHerein, a new template carbonization method is used to prepare calcite‐type nano‐calcium carbonate (CaCO3) with a core–shell structure using calcium hydroxide as a solute and Pluronic F‐127 as a templating and pore‐forming agent. Dopamine hydrochloride is added to control the size of calcium hydroxide particles. The morphology, particle size, and crystal type of CaCO3 are characterized via transmission electron microscopy, X‐ray diffraction, nanoparticle size, and zeta potentiometer. The creation of core–shell calcium carbonate nanoparticles is examined in relation to reaction circumstances (i.e., additive sequence, additive amount, and additive mixing time), carbonization temperature, liquid flow rate, and templates with varying chain lengths. Furthermore, a discussion is held regarding the formation mechanism of spherical core–shell calcium carbonate that is created using the innovative template carbonization method. The results show that the order, amount, liquid flow rate, and template type of additives have a significant effect on the crystal shape of calcium carbonate nanoparticles. The mixing time of additives has a significant effect on the particle size of calcium carbonate nanoparticles. Interestingly, the thickness of the shell depends on the carbonization temperature, and too slow or too fast flow rate will lead to the formation of cyclic calcium carbonate nanoparticles.

Streamlining regular liquid chromatography with MALDI-TOF MS and NMR spectroscopy using automatic full-contact splitless spotting interface and flash-tap fractioning collection

BackgroundHigh-resolution matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS) and nuclear magnetic resonance (NMR) spectroscopy are powerful tools to identify unknown psychoactive substances. However, in complex matrices, trace levels of unknown substances usually require additional fractionation and concentration. Specialized liquid chromatography systems are necessary for both techniques. The small flow rate of nano LC, typically paired with MALDI-TOF MS, often results in prolonged fractionation times. Conversely, the larger flow rate of semi-preparative LC, used for NMR analysis, can be time-consuming and labor-intensive when concentrating samples. To address these issues, we developed an integrated automatic system that integrated to regular LC. ResultAutomatic spot collector (ASC) and automatic fraction collector (AFC) were present in this study. The ASC utilized in-line matrix mixing, full-contact spotting and real time heating (50 °C), achieving great capacity of 5 μL droplet on MALDI plate, high recovery (76–116%) and rapid evaporation in 2 min. The analytes were concentrated 4–8 times, forming even crystallization, reaching the detection limit at the concentration of 50 μg L−1 for 12 psychoactive substances in urine. The AFC utilizes flexible tubing which flash-tapped the microtube's upper rim (3 mm depth) instead of reaching the bottom. This method prevents sample loss and minimizes the robotic arm's movement, providing a high fractionating speed at 6 s 12 psychoactive compounds were fractionated in a single round analysis (recovery: 81%–114%). Methamphetamine and nitrazepam obtained from drug-laced coffee samples were successful analyzed with photodiode array (PDA) after one AFC round and NMR after five rounds. SignificanceThe ASC device employed real-time heating, in-line matrix mixing, and full-contact spotting to facilitate the samples spotting onto the MALDI target plate, thereby enhancing detection sensitivity in low-concentration and complex samples. The AFC device utilized the novel flash-tapping method to achieve rapid fractionation and high recovery rate. These devices were assembled using commercially available components, making them affordable (400 USD) for most laboratories while still meeting the required performance for advanced commercialized systems.

Experimental and computational investigation of chaotic advection mixing in laminar rectangular stirred tanks

The phenomenon of chaotic advection mixing in laminar stirred tanks, particularly when handling high-viscosity fluids, represents a common and challenging issue in various chemical and biochemical industrial processes. The effectiveness of these mixing processes is often constrained by the stretching, folding, and squeezing of fluid particles. Previous research efforts have predominantly concentrated on the design and/or optimization of impellers and operation modes to increase the stretching and folding of fluid particles. However, the mechanism of triggering chaos through the squeezing of fluid particles remains comparatively less explored. This study endeavors to address the intricate problem of laminar mixing by proposing the utilization of unbaffled rectangular stirred tanks. Via a combined approach of experimental and computational investigations, we illustrate that the implementation of rectangular stirred tanks yields significant improvements in chaotic mixing within laminar flow regimes. This type of tank not only enhances the convective transport of fluids but also distorts or completely eliminates the segregation regions by squeezing. Remarkably, as the tank L/W ratio increases from 1 to 2.5, the observed asymptotic area coverage from a frontal perspective escalates from approximately 55 % to about 85 %. Concurrently, the dimensionless mixing time decreased significantly from 1950 to 350. Of particular note, macroscopic homogeneous mixing is observed in stirred tanks with L/W ratios of 2 and 2.5 at Re = 29, with dimensionless mixing times of 550 and 350, respectively. This work highlights the potential of rectangular stirred tanks as a simple and cost-effective system for laminar mixing applications. Furthermore, it also hints at the broader applicability of the approach in various industrial mixing contexts, such as the suspension of floating granules, entrainment of air, and others.

Electrospun PLLA/PEI nanofibers for controlled drug release behaviors and antibacterial efficiency

This study focused on the poly(L-lactic acid) (PLLA) polymer matrices by adding branched polyethyleneimine (PEI) as an aminolysis agent. Electrospun nanofibers were made by blending PLLA and PEI at various weight ratios (85-15, 75-15, and 65-35) and mixing times (0.5 h, 1 h, and 2 h). Amine groups were introduced into the nanofiber matrices, as confirmed by Fourier-transform infrared (FTIR) spectroscopy. The PLLA-PEI reaction was affected by mixing time, as shown by rheological measurements of absolute viscosity and surface tension. As a result, the nanofiber diameters decreased up to 42% and 89% with longer mixing time and higher PEI content, respectively. The aminolysis reaction rate increased up to 6.6 times with more PEI. Furthermore, the nanofibers had improved host-guest interactions, as demonstrated by contact angle, drug release, dye adsorption and water adsorption tests. The drug-loading capacity of the nanofibers was enhanced by PEI modification, as indicated by the release profile of tetracycline hydrochloride. The nanofibers also revealed more than 99.99% antibacterial activity due to the presence of the amine groups in PEI. Optimum mixing time and polymer ratio were proved to be substantial parameters to reach appropriate nanofiber and improve spinnability for further biomedical applications.

Investigation of mixing miscible liquids with high viscosity contrasts in turbulently stirred vessels using electrical resistance tomography

The time required to attain a sufficient degree of homogeneity i.e., mixing time, is an important parameter in mixing processes. This paper presents results from a study employing an experimental approach to estimate mixing times for a miscible Newtonian liquid mixture system with high viscosity contrasts in a turbulent stirred vessel. An Electrical Resistance Tomography (ERT) based technique has been adopted to monitor dimensionless mixing time across a range of additive viscosities, impeller designs, sizes, and speed. Dimensional analysis has been used to interpret these mixing time results in terms of the magnitude of the bulk inertia forces relative to the initial viscous forces within the added fluid. Critical non-dimensional numbers, uniting the properties of the two liquids, have been proposed as the criterion for avoiding undesirable operating conditions under which the mixing time is much longer than that required for mixing fluids with similar properties. The work proposes novel correlations for mixing time and incorporates a new dimensionless group, thereby enabling a more nuanced and accurate characterisation of mixing behaviours. This research stands to contribute to energy saving and waste minimisation efforts in the industry. It provides insights for process designers and simulation engineers, propelling a leap forward in the design and operation of mixing processes when dealing with liquid systems that have significant viscosity differences.