Type Of Agitation Research Articles

Gas hold-up for gas-liquid and biophase-gas-liquid systems agitated in a vessel equipped with vertical tubular baffles

The influence of the agitator type, agitator speed, superficial gas velocity, type of sugar (glucose or sucrose) and the presence of yeast in the system on the gas hold-up in an agitated vessel with 24 vertical tubular baffles (located on the circuit in the vessel) has been presented in this paper. The measurement of gas hold-up was conducted in an agitated vessel with inner diameter of D = 0.288 m and liquid height of H = 0.288 m. Three different agitators were used in the experimental study. Five gas-liquid and two biophase-gas-liquid systems were agitated in an agitated vessel. Air was used as gas. The influence of gas flow number, Weber number, the mass fraction of aqueous sugar solution ci, and mass fraction of yeast suspension ys for gas-liquid and biophase-gas-liquid systems on the gas hold-up ϕ was described mathematically. These equations do not have equivalents in the literature.

Computational Fluid Dynamics Analysis and Optimization of a Doublesuction Turbine Agitator

Background: As one of the essential pieces of chemical equipment, a reactor provides the necessary reaction space and conditions for the materials involved in the reaction during the stirring process. However, under typical operating conditions, issues such as uneven gas distribution, suboptimal gas-liquid mixing, and low product yield often arise in gas-liquid phase reactors. Purpose: To address the issues prevalent in current stirred reactors, a new design for a stirred reactor equipped with a double-suction turbine agitator was developed. Method: In this paper, a stirred reactor equipped with a double-suction turbine agitator was designed, and its three-dimensional modeling was conducted using SolidWorks. Computational Fluid Dynamics (CFD) simulations, based on the Euler-Euler two-phase approach with the RNG k −ε turbulence model, were performed to assess variables such as stirring speed, installation height, blade diameter and agitator inner diameter. The dispersion characteristics and flow field behaviors of the gas-liquid two-phase under varying conditions were comparatively analyzed. Optimizations were conducted across various parameters to enhance the gas mixing efficiency in the liquid phase. Result: The results show that a diameter of 370mm for the double-suction turbine agitator, an installation height of 640mm, a blade diameter of 500mm, and an inner hole diameter of 200mm yield optimal gas-liquid two-phase mixing performance. This configuration results in a broad and uniform gas distribution within the reactor, maintaining a desired high level of gas holdup at specific positions. Conclusion: The double suction turbine agitator is a type of radial agitator. During operation, it induces significant centrifugal forces in the liquid, exerts a robust shear effect, and enhances the mixing of the gas-liquid phases, thereby increasing the production efficiency of the product.

Advances in Bacterial Cellulose Production: A Scoping Review

The versatility, contribution to sustainability, and diversity of applications of bacterial cellulose require large-scale production processes and new alternatives in terms of biological systems that, under controlled conditions, favor the growth and production of this biomaterial. This review article describes the technologies developed and the advances achieved in regard to the production of bacterial cellulose on a small and large scale, according to the findings evidenced in the scientific literature in the last ten years. A review, based on the guidelines in the PRISMA® methodology, of a selection of articles was carried out, with a Cohen’s Kappa coefficient of 0.465; scientific databases, such as Web of Science, SCOPUS, PubMed, Taylor and Francis, and ProQuest, were considered. There is a wide variety of bacterial pulp production systems and the design of such a system is based on the type of cellulose-producing bacteria, oxygen requirements, mixing and agitation, temperature control, sterilization and cleaning requirements, and production scalability. The evolution in the development of bioreactors for bacterial cellulose has focused on improving the production process’s efficiency, productivity, and control, and adapting to the specific needs of bacterial strains and industrial applications.

Comparison of depression with anxious distress and melancholic depression from the perspective of psychomotor disturbance.

In the DSM-5, it is specified that severe cases of major depressive disorder with anxious distress (ANXD) may be accompanied with motor agitation. Agitation, on the other hand, is one of the main characteristics of major depressive disorder with melancholic features (MEL). The purpose of this study was to compare ANXD and MEL in terms of psychomotor disturbance. A total of 106 patients with major depressive disorder were included in the study. Psychomotor disturbance was assessed using the CORE measure. The associations of ANXD and MEL with the CORE measure subscales of psychomotor retardation, agitation, and noninteractiveness were analyzed using multivariate logistic analysis. Retardation scores (odds ratio [OR] = 0.63, 95% confidence interval [CI] = 0.52-0.77) were associated with fewer diagnoses of ANXD, whereas agitation scores (OR = 2.23, 95% CI = 1.60-3.13) were associated with more diagnoses of ANXD. Both noninteractiveness (OR = 1.23, 95% CI = 1.06-1.42) and agitation (OR = 1.27, 95% CI = 1.02-1.58) scores were associated with increased diagnoses of MEL. Among the characteristics of psychomotor disturbance, agitation is a common feature of both ANXD and MEL, and ANXD and the agitated type of MEL may be overlapping concepts. On the other hand, ANXD is distinguished from the retarded type of MEL by its low level of retardation, whereas MEL but not ANXD is characterized by noninteractiveness.

Improvement of mechanochemical leaching of zinc oxide ore — Optimization of grinding parameters for basket grinder

The mechanochemical leaching (MCL) process presents promising potential for efficiently extracting zinc from zinc oxide ores. This study analyzed the effects of several grinding parameters, including the agitator type, grinding ball size and material, grinding ball addition, and stirring speed, on the zinc leaching. Among them, the agitator type affects the flow form and mass transfer rate of the solution, the grinding ball size and material affects the crushing effect of the mineral powder, the grinding ball addition affects the state of motion of the grinding ball, and the stirring speed affects the grinding effect of the grinding ball on the mineral powder, which in turn affects the extraction of zinc. Experimental results show that optimization of these grinding parameters results in higher zinc leaching rates at lower energy costs. Under optimal conditions, the zinc leaching rate can reach 86.02% through the optimized MCL process, which is 9.38% higher than the conventional leaching process. Analysis techniques, such as XRD, particle size analysis, SEM-EDS, and EPMA, were utilized to examine leaching residues. The leaching mechanism of MCL process is derived under mechanical activation to destroy the insoluble product layer of zinc oxide ores (such as gangue), expose the zinc containing components, change the physical and chemical properties (such as mineral structure, particle size, and specific surface area), and enhance the reactivity of zinc oxide ore, and enhancing zinc leaching. The optimized MCL process offers the benefits of a straightforward process, reduced energy consumption, and eco-friendliness. This process has vast potential in the development and utilization of low-grade refractory zinc oxide ores in the Lanping area.

Microcarrier-based clinical-grade manufacturing of therapeutic Wharton's jelly mesenchymal stromal cells

Due to their immunomodulatory and anti-inflammatory properties, tissue repair capabilities and regenerative potential, Wharton's jelly mesenchymal stem/stromal cells (WJMSCs) have been widely investigated as potential treatment for diverse clinical indications. WJMSCs have been found to be well-tolerated and safe, positioning them as a promising candidate for cellular therapy. To address the commercial need for manufacturing WJMSCs for clinical applications, the production scale should be capable of generating large quantities of cells that retain their expected identity, purity and potency. This study aimed to establish a current Good Manufacturing Practice (cGMP) compliant robust and scalable expansion process representing a critical step towards a cGMP-compliant large-scale production platform for WJMSC-based clinical applications. Using our in-house cGMP-manufactured WJMSCs, which are currently being tested in a Phase Ib clinical trial (NCT03158896) using two-dimensional (2D) planar systems, we optimized various culture parameters including type of microcarrier, seeding density, agitation and culture feed regime in a 3D microcarrier-based culture system in spinner flasks. The results showed that cell adhesion was potentiated under intermittent stirring (3 min of agitation at 25 rpm followed by a period of non-agitation for 30 min), with reduced supplementation (0.05%) during the initial 8 h of cultivation with an initial cell concentration of 0.45 × 105 cells/mL. Microcarrier-based WJMSC expansion in spinner flasks achieved greater cell densities of 1.67 × 106 cells/mL with a maximum of 37-fold expansion, yielding ∼84 × 106 cells after 6 days of culture with a 95% harvest efficiency. Additionally, post 3D expansion, WJMSCs maintained their phenotypic characteristics, differentiation potential, normal karyotype, functional properties and sterility in the culture systems evaluated. This cGMP-compliant expansion process described herein demonstrates a successful transition of an established 2D planar culture process of clinical grade WJMSCs to 3D microcarrier-based suspension process generating higher cell yields, is cost-effective and represents an important step toward fulfilling the commercial demand of clinical grade mesenchymal stromal cells.

Modeling and optimization of dyeing process of polyamide 6 and woolen fabrics with plum-tree leaves using artificial intelligence

The dyeing process of textile materials is inherently intricate, influenced by a myriad of factors, including dye concentration, dyeing time, pH level, temperature, type of dye, fiber composition, mechanical agitation, salt concentration, mordants, fixatives, water quality, dyeing method, and pre-treatment processes. The intricacy of achieving optimal settings during dyeing poses a significant challenge. In response, this study introduces a novel algorithmic approach that integrates response surface methodology (RSM), artificial neural network (ANN), and genetic algorithm (GA) techniques for the precise fine-tuning of concentration, time, pH, and temperature. The primary focus is on quantifying color strength, represented as K/S, as the response variable in the dyeing process of polyamide 6 and woolen fabric, utilizing plum-tree leaves as a sustainable dye source. Results indicate that ANN (R2 ~ 1) performs much better than RSM (R2 > 0.92). The optimization results, employing ANN-GA integration, indicate that a concentration of 100 wt.%, time of 86.06 min, pH level of 8.28, and a temperature of 100 °C yield a K/S value of 10.21 for polyamide 6 fabric. Similarly, a concentration of 55.85 wt.%, time of 120 min, pH level of 5, and temperature of 100 °C yield a K/S value of 7.65 for woolen fabric. This proposed methodology not only paves the way for sustainable textile dyeing but also facilitates the optimization of diverse dyeing processes for textile materials.

Physiological Profiling of Agitation in Dementia: Insights From Wearable Sensor Data.

The number of people with dementia is expected to triple to 152 million in 2050, with 90% having accompanying behavioral and psychological symptoms (BPSD). Agitation is among the most critical BPSD and can lead to decreased quality of life for people with dementia and their caregivers. This study aims to explore objective quantification of agitation in people with dementia by analyzing the relationships between physiological and movement data from wearables and observational measures of agitation. The data presented here is from 30 people with dementia, each included for 1 week, collected following our previously published multimodal data collection protocol. This observational protocol has a cross-sectional repeated measures design, encompassing data from both wearable and fixed sensors. Generalized linear mixed models were used to quantify the relationship between data from different wearable sensor modalities and agitation, as well as motor and verbal agitation specifically. Several features from wearable data are significantly associated with agitation, at least the p < .05 level (absolute β: 0.224-0.753). Additionally, different features are informative depending on the agitation type or the patient the data were collected from. Adding context with key confounding variables (time of day, movement, and temperature) allows for a clearer interpretation of feature differences when a person with dementia is agitated. The features shown to be significantly different, across the study population, suggest possible autonomic nervous system activation when agitated. Differences when splitting the data by agitation type point toward a need for future detection models to tailor to the primary type of agitation expressed. Finally, patient-specific differences in features indicate a need for patient- or group-level model personalization. The findings reported in this study both reinforce and add to the fundamental understanding of and can be used to drive the objective quantification of agitation.

Effect of factors on phytochemical compound extraction from Asystasia gangetica through factorial analysis

This study aims to identify the phytochemical compounds of Asystasia gangetica and to investigate the best extraction conditions to maximize phytochemical concentration. The factors affecting the concentration of total phenolic compound (TPC), total flavonoid content (TFC) and antioxidant activity (AA) of Asystasia gangetica were evaluated through the two-level factorial analysis including types of solvent (methanol and ethanol), solvent percentage (70 and 85%), extraction times (2 and 5 hours), temperature (50 and 80℃) and agitation (absent or present) to determine the most significant factor. The results show that solvent percentage contributed most to the TPC and agitation in TFC extraction. Meanwhile, the temperature, agitation and solvent percentage were significant for AA. The overall best conditions for phytochemical extraction were found at 5-hour extraction times, 70% methanol, 80℃ temperatures with agitation. At this condition, the highest recorded TPC, TFC and AA were 0.2149, 0.3281 and 6.6360 respectively. Acknowledging the suitable range of processing factors during phytochemical extraction could significantly affect the yields. The factorial analysis could be useful to tailor the range of factors chosen to obtain the desired outcome.

Biochar-based polymeric film as sustainable and efficient sorptive phase for preconcentration of steroid hormones in environmental waters and wastewaters

BackgroundThe environmental impact of sample preparation should be minimized through simplification of the procedures and the use of natural, renewable and/or reusable materials. In such scenario, thin-film microextraction fulfils the former criteria, as it enables few steps and miniaturization, thus small amount of extraction phase. At the same time, the use of sorbents such as biochars obtained from biomass waste is even more promoted due to their availability at low cost and increased life-cycle in a circular economy vision. However, it is not always easy to combine these criteria in sample preparation. ResultsA thin film microextraction was developed for the determination of steroids in aqueous samples, entailing a membrane made of cellulose triacetate and a wood-derived biochar (Nuchar®) as carbon precursor. Different characterization techniques showed the successful preparation, whereas the sorption kinetics experiments demonstrated that biochar is responsible for the extraction with the polymer acting as a smart support. After a study about membranes’ composition in terms of biochar amounts (4 %, 10 %, 16 % wt) and type of synthesis set up, the ceramic 3D-mold was selected, achieving reproducible and ready-to-use membranes with composition fixed as 10 %. Different elution conditions, viz. type and time of agitation, type, composition and volume of eluent, were evaluated. The final microextraction followed by HPLC-MS/MS quantification was successfully validated in river and wastewater treatment plant effluent samples in terms of accuracy (R% 64–123 %, RSD<19 % in river; R% 61–118 %, RSD <18 % in effluent, n = 4), sensitivity (MQLs 0.2–8.5 ng L−1) and robustness. SignificanceThis novel biochar-based polymeric film proved to be a valid and sustainable sorbent, in terms of extraction capability, ease of preparation and greenness. By comparison with literature and the greenness evaluation with the most recent metric tools, this method expands the potential applicability of the thin-film microextraction and opens up innovative scenarios for sustainable procedures entailing the use of biochars entrapped in bio-polymers.

Analyzing of hydrodynamic stress and mass transfer requirements of a fermentation process carried out in a coaxial bioreactor: a scale-up study.

Fluid hydrodynamic stress has a deterministic effect on the morphology of filamentous fungi. Although the coaxial mixer has been recognized as a suitable gas dispersion system for minimizing inhomogeneities within a bioreactor, its performance for achieving enhanced oxygen transfer while operating at a reduced shear environment has not been investigated yet, specifically upon scale-up. Therefore, the influence of the impeller type, aeration rate, and central impeller retrofitting on the efficacy of an abiotic coaxial system containing a shear-thinning fluid was examined. The aim was to assess the hydrodynamic parameters, including stress, mass transfer, bubble size, and gas hold-up, upon conducting a scale-up study. The investigation was conducted through dynamic gassing-in, tomography, and computational fluid dynamics combined with population balance methods. It was observed that the coaxial bioreactor performance was strongly influenced by the agitator type. In addition, coaxial bioreactors are scalable in terms of shear environment and oxygen transfer rate.

Alpha 2 agonists for sedation to produce better outcomes from critical illness (A2B trial): protocol for a mixed-methods process evaluation of a randomised controlled trial

IntroductionAn association between deep sedation and adverse short-term outcomes has been demonstrated although this evidence has been inconsistent. The A2B (alpha-2 agonists for sedation in critical care) sedation trial is...

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

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

Comparative study of heat transfer in apparatuses with turbine and blade agitators

In the framework of this research, modeling of flows and heat transfer in apparatuses with turbine and blade agitators using the ANSYS CFX software package has been carried out. The purpose of the work is to create digital prototypes of apparatuses with stirring devices to improve the effectiveness of technological processes of various chemical and petrochemical industries. Modeling was carried out on the basis of three different objectives, including the processes of water heating and mixture of water with glycerol. In each objective, the heating and circulation characteristics of the liquid during mixing using turbine and blade agitators were investigated. The effects of parameters such as apparatus wall temperature, water and mixture flow rate, rotation speed and agitator type on the time characteristics of reaching steady-state were evaluated. The simulation results demonstrated that turbine and blade agitators provide more efficient mixing and heating of the liquid compared to blade agitators, all other conditions being equal. Fluid temperatures reached higher values in a shorter time when turbine agitators were used, making them preferable for processes where intensive mixing and rapid heating are required. This approach can be useful to optimize mixing processes on production lines and improve the energy efficiency of production facilities.

Numerical insight into heat transfer enhancement by granules inner-migration in a moving bed: A performance comparison between slanted-stick and plow-shaped agitator

Waste heat recovery of high-temperature granules is one of the most promising sustainable energy supply and carbon reduction ways for industry. A moving bed indirect heat exchanger (MBIHE) with inner-migration was proposed for granular heat recovery. Granule migration and the enhanced heat transfer induced by two types of agitators (i.e., agitator with slanted stick As and with plow-shaped surface Ap) in the MBIHE are analyzed based on DEM coupled with CFD. Owing to the effective agitation, the average heat transfer coefficient in the granule side is enhanced to ∼3 times compared to that without agitation. The heat recovery efficiency in the moving bed reached more than 70% with the agitations of either As or Ap. The heat efficiency of As is ∼7% higher than that of Ap, but with at least 60% greater rotational torque. To ensure reliable agitation, the Ap is suggested to be adopted in the MBIHE to induce granule migration.

Bioactivity of crude extract produced by endophytic fungi isolated from Ziziphus spina-christi (Nabq) leaves for antimicrobial evaluation as well as optimization of culture medium conditions

Twenty fungal endophytes were isolated from Nabq, and plug diffusion screening revealed four of those isolates to be promising. These isolates were identified molecularly as Aspergillus sp. of Sect. Flavi (ZSEFL2) and Sec. Niger (ZSEFL14), and Penicillium spp. closest related to Penicillum crustosum (ZSEFL15, 19). Investigations were conducted to determine the effects of culture parameters, such as the type of culture medium, incubation temperature, initial pH and agitation, on the production of antimicrobial metabolites in a culture filtrate extract. Using the disk diffusion technique, antimicrobial metabolite synthesis was evaluated. In comparison to the other three distinct culture media (PDB-y, rice, and Cz), PDB demonstrated to be the best culture medium for the four tested fungal endophytes, exhibiting high levels of the Antimicrobial Index (AI). Also, a restricted range of incubation temperatures resulted in the formation of bioactive metabolites, but raising the incubation temperatures from 25 to 30 °C increased the amount of bioactive metabolites produced. Moreover, the best initial hydrogen concentration typically ranged from pH 5 to 6. Finally, when the conditions changed from stationary to shaking, the bioactive secondary metabolite's antimicrobial efficacy reduced. The behavior of the four examined fungal isolates was consistent, and they all required the same conditions to produce the most bioactive metabolites. Moreover, ethyl acetate extract's MIC values against the investigated bacterial and fungal human pathogens ranged from 0.19 to 6.25 mg/mL.

Novel bionanomaterial based on Spirulina maxima algae and graphene oxide for lead microextraction and determination in water and infant beverages.

A new hybrid bionanomaterial composed of graphene oxide (GO) and Spirulina maxima (SM) algae was synthesized and applied to develop a preconcentration method based on the dispersive micro-solid phase extraction (D-μ-SPE) technique for the determination of Pb in water and infant beverages. In this work, Pb(II) was extracted with 3mg of the hybrid bionanomaterial (GO@SM) followed by a back-extraction step using 500 µL of 0.6mol L-1 HCl. Then, a 1.5 × 10-3mol L-1 dithizone solution was added to the sample containing the analyte to form a purplish red-colored complex for its detection by UV-Vis spectrophotometry at 553nm. An extraction efficiency of 98% was obtained after optimization of experimental variables such as GO@SM mass, pH, sample volume, type, and time of agitation. A detection limit of 1μg L-1 and a relative standard deviation of 3.5% (at 5μg L-1 Pb(II), n = 10) were achieved. The calibration linear range was obtained between 3.3 and 95µg L-1 Pb(II). The proposed method was successfully applied for the preconcentration and determination of Pb(II) in infant beverages. Finally, the greenness degree of the D-µ-SPE method was evaluated using the Analytical GREEnness calculator (AGREE), obtaining a score of 0.62.

Design and analysis of horizontal crystallizer for agro-chemical industries

Crystallization is a process in which hot solution is allowed to cool in a shell to form crystals at the end of the process. Crystallization is predominantly used in chemical industries. In most of the industries vertical crystallizer are used for continuous crystallization. The proposed project is horizontal crystallizer used for batch crystallization. In this project we have tried to solve problem wherein blades were subjected to impact load and produced a greater number of vibrations in the crystallizer, due to which blades were failing at the location where blades were connected to the shaft end because of more stresses. Also, the blades will be subjected to elevated temperature for some period. To solve this problem some research about various types of agitators is available. Designing of two types of blades those are single helical blades and double helical blades has been done. These blades will be suitable for mixing viscous solution and these blades works on the principle of shearing the solution and pushing it. These blades will produce fewer vibrations as compared to pedal blades used in the industries. Static structural analysis and Steady State Thermal Analysis on blades as well as on Shell has been done. The Stresses and deformation pattern are produced within safety limits. After performing the Design and Analysis of Shell and Blades, a model which has a capacity of 440 Litres has been fabricated and the results are interpreted. The fabricated crystallizer is implemented in the chemical industry which is providing better crystals as compared with the already in use crystallizer.

Evaluation modified luffa with silver nanoparticles (LF/AgNPs) for removal of a nonsteroidal anti-inflammatory (IBUPROFEN) from aqueous media

This study has investigated luffa as a natural adsorbent modified with silver nanoparticles to sequestrate ibuprofen from aqueous media. Adsorption ibuprofen as an environmental pollutant from aqueous media was studied by various factors such as agitation type, pH, initial drug concentration, contact time, agitation rate, and adsorbent dosage. The optimized experimental parameters were achieved by a one-at-a-time method in 60 min employing vortex in pH = 5, initial concentration of 200 µg/mL, and adsorbent dosage of 25 mg. Isotherms were fitted best to the Freundlich model. Kinetics shows that the adsorption of the drug follows a pseudo-second-order model. According to the obtained results, the adsorption capacity of the prepared adsorbate was 71 mg/g, and 92% of the ibuprofen was removed in the aqueous solutions under optimal conditions. Due to the modification of luffa by silver nanoparticle, the surface charge has been changed and also active sites of adsorbent has been increased. Consequences, π-metal interaction, hydrogen bonding, electrostatic interactions and π-π stacking were involved in the advancement the adsorption mechanism. The results confirmed that the modified luffa is a suitable adsorbent for removing ibuprofen from aqueous solutions.