Stirring Procedure Research Articles

Natural Deep Eutectic Solvents as a Novel Bio-Based Matrix for Ready-to-Use Natural Antioxidants-Enriched Ingredients: Extraction and Formulation Optimization

The escalating consumer demand for sustainable cosmetic ingredients poses distinct challenges, particularly concerning their stability within the final formulation. Although natural resources offer a pool of antioxidant molecules with diverse structures and polarities, achieving stabilization combined with a comprehensive antioxidant profile often proves incompatible with practical preformulation considerations. Notably, Calendula, which is rich in both polar (glycosylated flavonoids) and nonpolar (carotenoids) antioxidants, is a standout candidate. Nevertheless, the market lacks an ingredient embodying this diversity, primarily due to the limited polarity range of available usable solvents. Natural deep eutectic solvents (NaDESs) emerge as a promising solution. This study explores NaDES technology with the goal of developing a unique Calendula extract enriched in both polarities of antioxidants, a composition that is unattainable with traditional solvents. A screening of 12 NaDESs with varying polarities highlighted a NaDES based on betaine and glycerol as particularly effective, outperforming ethanol. Leveraging response surface methodology, an optimal mechanical stirring procedure for extraction was identified. The resulting extract showed a total flavonoid content of 45.42 ± 0.85 mg eq rutin/g of biomass and a total carotenoid content of 383.54 ± 4.73 µg/g biomass. It was then incorporated into a sustainable cream (1% and 10%wt) using an innovative mixing technology. The resulting creams demonstrated stability over 90 days, with no significant deviations in pH or rheological properties compared to the control, and a droplet size that was inferior to 10 µm. This study lays the foundation for pioneering natural antioxidant cocktail-loaded ingredients that are suitable for eco-friendly cosmetic formulations, substantiating the viability of integrating environmentally friendly ingredient-based solvents.

Potency of emulsifiable concentrate and nanoemulsion formulations as green insecticides against two insects, Aphis craccivora and Liriomyza trifolii

The current research aims to develop emulsifiable concentrates (EC) and nanoemulsions derived from the plant essential oils of Salvia officinalis (L.) and Melissa officinalis (L.) at a concentration of 5%. The toxicity of the prepared formulations was evaluated against two insect species, the cowpea aphid, Aphis craccivora (Koch), and the broad bean leafminer, Liriomyza trifolii (Burgess). EC preparations were formed by mixing the essential oils with Tween 80, vegetable, and mineral oils. The nanoemulsions were manufactured by mixing different ratios of the essential oils and the surfactant (Tween 80) into an aqueous solution, followed by an ultrasonic emulsification process. The results showed that both EC and nanoemulsions with a ratio of essential oil to Tween 80 of 1:2 after 10 min of sonication passed the physical characteristics. The particle droplet size, zeta potential, and transmission electron microscopy (TEM) were measured for the successful nanoemulsion formulations. The ultrasonication and stirring procedures lowered the amounts of essential oils during preparations of S. officinalis and M. officinalis nanoemulsions to 17% and 20%, respectively. The laboratory trials elucidated that EC formulations were more potent than nanoemulsions for two insect species after a short period of time. While the field experiments showed that nano-formulations were more efficient than EC formulations with time elapsing. The results suggested that the prepared nanoemulsions can be used as eco-friendly alternatives to synthetic insecticides for controlling A. craccivora and L. trifolii infestations.

Highly Improved Acetone Gas Sensing Performance of Mesoporous Cobaltosic Oxide Nanoparticles and Physical Mechanism

Mesoporous Cobaltosic oxide nanoparticles are now widely employed in a variety of applications across the world. It is both environmentally and economically favorable. It was well prepared in this study using a cost-effective thermal stirring procedure. The X-ray diffraction method at ambient temperature was used to explain the formation of single spinel structure, purity, and cat-ion distribution of the material, and the lattice constant of mesoporous Cobaltosic oxide nanoparticles was 8.23 Å. SEM and EDX examination were used to investigate phase formation, elemental content, and surface morphology. The average particle size for primitive mesoporous Cobaltosic oxide nanoparticles is 17nm. DRS determined the band gap for mesoporous Cobaltosic oxide nanoparticles to be 1.48 eV for direct band bending and 2.19 eV for indirect band gap. The sensitivities of the sample are greater due to the mesoporous-structures with a large surface area. Mesoporous Cobaltosic oxide nanoparticles have a greater specific surface area (59.63m2 g− 1), resulting in good acetone gas sensing characteristics at the optimal working temperature of 150°C. Furthermore, the sample exhibits high stability and selectivity against acetone gas. The gas-sensing mechanism is determined by comparing the sensitivity of Mesoporous Cobaltosic oxide nanoparticles to surface oxygen and acetone gas adsorption. It is the best among the top other materials, according to the results.

Vortex generation in stirred binary Bose-Einstein condensates

Binary Bose-Einstein condensates of two distinct atomic species are studied, with interesting effects being verified due to the imbalance of atomic masses. We study the formation of vortices and associated turbulence flows created by stirring two mass-imbalanced coupled Bose-Einstein condensates in the miscible regime. We consider the mixture in the laboratory frame, confined in a pancake-like harmonic trap slightly perturbed elliptically by a time-dependent periodic potential, which introduces turbulent dynamics with final stable patterns of vortices, induced by the periodicity of the perturbation. Derived rotational frequencies are shown to be associated with the observed vortex patterns in the asymptotic regime, with a correspondence between the stirring procedure and a direct time-independent approach being indicated. It was also confirmed that a larger pattern of vortices is supported by the higher mass condensed species at the same frequency. For the experimentally accessible mixtures $^{85}\mathrm{Rb}\text{\ensuremath{-}}^{133}\mathrm{Cs}$ and $^{85}\mathrm{Rb}\text{\ensuremath{-}}^{87}\mathrm{Rb}$, we numerically solve the equations of motion and analyze the system dynamics using a range of measures including energy spectra. In the transient turbulent regime, spectral analysis shows evidence for the characteristic ${k}^{\ensuremath{-}5/3}$ Kolmogorov classical law associated with turbulence, modified by the universal ${k}^{\ensuremath{-}3}$ vortex core scaling in the ultraviolet regime.

Proposal for a Standard Protocol to Assess the Rheological Behavior of Thickening Products for Oropharyngeal Dysphagia

Increasing shear viscosity (ShV) in thickening products (TP) is a valid therapeutic strategy for oropharyngeal dysphagia (OD). However, salivary amylase in the oral phase and shear rate in the pharyngeal phase of swallowing can change the viscosity of TPs when swallowed. This study aims to design and validate a rheological protocol to reproduce the oral and pharyngeal factors that affect the therapeutic effect of TPs and report the viscosity measurements in a standardized scientific and precise manner. We measured (a) the variability of the ShV measurements across several laboratories; (b) the in vitro and ex vivo properties of TPs and (c) the impact of the X-ray contrast Omnipaque, temperature and resting time on the rheological properties of TPs. A common protocol was applied in four international laboratories to assess five ShV values (100, 200, 400, 800 and 1600 mPa·s) for the xanthan-gum TP Tsururinko Quickly (TQ). The protocol included the dose (g/100 mL water), stirring procedure and standing time before measurement. Each value was characterized at the shear rate of 50 and 300 s-1 pre- and post-oral incubation in eight volunteers. The effect of temperature, standing time and Omnipaque was assessed. The main results of the study were: (a) The mean intra-laboratory variability on the ShV at all levels was very low: 0.85%. The mean inter-laboratory variability was higher: 9.3%; (b) The shear thinning of TQ at 300 s-1 was 75-80%. Increasing the temperature or standing time did not affect the ShV, and oral amylase caused a small decrease; (c) Omnipaque slightly decreased the dose of TP and hardly affected the amylase resistance or shear thinning. This study showed that different laboratories can obtain very accurate and similar ShV measurements using this protocol which uses scientific, universal SI units (mPa·s). Our protocol accurately reproduces oral and pharyngeal factors affecting the therapeutic effect of TPs. The addition of X-ray contrast did not produce significant changes.

Highly catalysis MOFCe supported Ag nanoclusters coupled with specific aptamer for SERS quantitative assay of trace dopamine

A cerium metal organic framework-loaded silver nanocluster (MOFCeAgNC) is synthesized by a facile stirring procedure with trimesic acid, cerium nitrate, silver nitrate and NaBH4, which exhibites strong catalytic activity in the indicated reaction of HAuCl4-sodium lactate (SL). MOFCeAgNC can sensitively detect dopamine (DA) by surface-enhanced Raman scattering (SERS) and resonance Rayleigh scattering (RRS) techniques with a detection concentration range of 0.01–0.25 nmol/L and a detection limit of 0.008 nmol/L. Based on the specific binding of aptamer (Apt)-DA and the catalytic amplification strategy of MOFCeAgNC on HAuCl4-SL, a sensitive and convenient DA platform for dual-mode detection of SERS and RRS is constructed. In addition, the platform is successfully applied to detect DA in human serum with satisfactory recoveries (95.7–102%).

Cold plasma treatment of seeds: deciphering the role of contact surfaces through multiple exposures, randomizing and stirring

Cold plasma technologies are an efficient approach to improve the germination properties of seeds, especially in a stacking configuration within a dielectric barrier device (DBD). In such dry atmospheric plasma priming process, we show that a helium-nitrogen plasma treatment of 20 min can reduce the median germination time of lentil seeds from 1420 min to 1145 min, i.e. a gain in vigor of 275 min (or +19.4%). Considering that this result depends on the plasma-seed interaction and therefore on the contact surfaces between the seeds and the plasma, a topographic modeling of a 100 seeds-stack is performed in the DBD. This model drives to the distinction between the seed–seed contact surfaces (276 contacts standing for a total area of 230.6 mm2) and the seed-wall contact surfaces (134 contacts standing for a total area of 105.9 mm2). It turns out that after a single plasma treatment, the outer envelope of each seed is 92% exposed to plasma: a value high enough to support the relevance of the plasma process but which also opens the way to process optimizations. In this outlook, we propose to replace the single 20 min plasma treatment by a ‘plasma sequence’, i.e. a succession of shorter plasma treatments whose total duration remains 20 min. Between two successive plasma treatments, the seeds can follow either a trapping procedure (seeds in same positions and orientations) or a randomizing procedure (seeds in same positions but reoriented) or a stirring procedure (seeds vigorously shaken). As an example, a sequence of ten plasma treatments (upon 2 min) separated by short stirring procedures leads to a gain in vigor as high as 405 min (+28.5%) vs 275 min (+19.4%) for a single plasma treatment of 20 min. We propose to understand these results by correlating the gain in vigor with the water uptake of the seeds (increase from 29% to 55%) and the wettability state of their coating (decrease of contact angle from 113.5° to about 38°).

Multi -Response optimization of Electric Discharge Machining (EDM) process parameter for Aluminum based Hybrid Metal Matrix Composite using GRA

Aluminum based hybrid metal composite (MMC) have been applied to many various applications in the area of automobiles and aerospace. This research article shows the multi-response optimization of EDM of process parameter for Aluminum based metal matrix hybrid composite (Aluminum 6061/Al2O/TiO2). The optimum process parameter of EDM as like pulse on time (Ton), current (Ip), duty cycle (t), voltage (V) on material removal rate and surface roughness were investigated. Hybrid Aluminum metal matrix composite was machined by using tool which is made of copper materials, of ϕ12 mm for experimentation. The mechanical stirring procedure is used to fabricate the hybrid MMC. The design of experiments was conduct through the Response Surface Methodology (RSM). The experimental result declares that the main influencing input parameter is current.

Study of radioactive particle tracking using MCNP-X code and artificial neural network

Agitators or mixers are highly used in the chemical, food, pharmaceutical and cosmetic industries. During the fabrication process, the equipment may fail and compromise the appropriate stirring or mixing procedure. Besides that, it is also important to determine the right point of homogeneity of the mixture. Thus, it is very important to have a diagnosis tool for these industrial units to assure the quality of the product and to keep the market competitiveness. The radioactive particle tracking (RPT) technique is widely used in the nuclear field. In this paper, a method based on the principles of RPT is presented. Counts obtained by an array of detectors properly positioned around the unit will be correlated to predict the instantaneous positions occupied by the radioactive particle by means of an appropriate mathematical search location algorithm. Detection geometry developed employs eight NaI(Tl) scintillator detectors and a Cs-137 (662 keV) source with isotropic emission of gamma-rays. The modeling of the detection system is performed using the Monte Carlo Method, by means of the MCNP-X code. In this work, a methodology is presented to predict the position of a radioactive particle to evaluate the performance of agitators in industrial units by means of an Artificial Neural Network.

Homogeneous and stable carbon nanotube dispersion assisted by cellulose in NaOH/thiourea aqueous solution

Carbon nanotubes (CNTs) have been proposed as next-generation lightweight structural materials, yet their application is facing challenges due to the poor dispersity in most solvents, especially in aqueous solution. Here, we report a facile and robust strategy for the rapid and scalable preparation of homogeneous and stable CNT dispersion assisted by cellulose in NaOH/thiourea aqueous solution. The whole process only needs a mild stirring procedure at ice-bath without any pre-treatment of raw materials. It is demonstrated that the suitability of the CNT dispersion for aqueous self assembly of various functional materials, ranging from zero-dimensional (0D) microsphere to three-dimensional (3D) monolith through various molding techniques. Also, the CNT dispersion can be used as ink to prepare CNT-based paper and textile through simply dyeing commercial filter paper and textile, and to directly write on the paper by syringe, indicating the great potential for flexible and wearable devices.

Analysis and Optimal Velocity Control of a Stochastic Convective Cahn\u2013Hilliard Equation

A Cahn–Hilliard equation with stochastic multiplicative noise and a random convection term is considered. The model describes isothermal phase-separation occurring in a moving fluid, and accounts for the randomness appearing at the microscopic level both in the phase-separation itself and in the flow-inducing process. The call for a random component in the convection term stems naturally from applications, as the fluid’s stirring procedure is usually caused by mechanical or magnetic devices. Well-posedness of the state system is addressed, and optimisation of a standard tracking type cost with respect to the velocity control is then studied. Existence of optimal controls is proved, and the Gâteaux–Fréchet differentiability of the control-to-state map is shown. Lastly, the corresponding adjoint backward problem is analysed, and the first-order necessary conditions for optimality are derived in terms of a variational inequality involving the intrinsic adjoint variables.

Development of a stirring–assisted ferrofluid–based liquid phase microextraction method coupled with dispersive liquid–liquid microextraction for the extraction of some widely used pesticides from herbal distillates

ABSTRACT In present study, a new sample pretreatment method based on the combination of stirring-assisted ferrofluid-based liquid phase microextraction and dispersive liquid–liquid microextraction has been developed for the extraction of some pesticides (diazinon, deltamethrin, fenpropathrin, phosalone, prometryn, simazine, and terbutryn) from herbal distillate samples. In this method, a few microlitre of a synthesised ferrofluid as an extraction solvent is added into the sample solution containing the analytes and the mixture is stirred at a high rate to increase the contact area between the ferrofluid and sample solution. Then the stirring procedure is stopped and the ferrofluid droplets containing the analytes are collected on the surface of stir bar. In the next step, the stir bar is washed with acetonitrile. In the following, the obtained mixture of acetonitrile and ferrofluid is rapidly injected into deionised water. The ferrofluid droplets are settled down at the bottom of a conical test tube and after back-extraction of the analytes into n-hexane, an aliquot of the extractant phase is injected into gas chromatography–mass spectrometry. Under optimum conditions, the introduced method offered high enrichment factors (1643−1884) and extraction recoveries (82–94%), low limits of detection (3.1–7.3 ng L–1) and quantification (10.3–24.3 ng L–1), and an acceptable repeatability (relative standard deviation ≤ 7.9%).

CQDs@NiO: An Efficient Tool for CH4 Sensing

A composite material based on carbon quantum dots (CQDs) and NiO was prepared and tested for methane sensing. The synthesis procedure is simple and foresees the preparation of the CQDs by citric acid pyrolysis and NiO by hydrothermal synthesis. A phase sonication and stirring procedure yielded the composite CQDs@NiO at different loads. The composites were characterized by X-ray diffraction, ultraviolet–visible light (UV–Vis) spectroscopy, SEM microscopy, energy-dispersive spectroscopy (EDS) mapping, and surface area, porosity, and impedance measurements. A gas sensor was built in-house and used to probe the response of the synthesized samples to CH4 detection, at constant environmental humidity. The CQDs@NiO at 1% weight load displayed excellent performances in terms of gas response both vs. temperature and vs. concentration, whereas higher loads resulted in CQD aggregation and diminished output. Response/recovery times of the 1%CQDs@NiO sample were good, as well as the selectivity and the stability over time and for variable environmental humidity. The estimated limit of detection was 0.1 ppm.

Proximate stochastic chiral symmetry breaking is mechanically tunable: formation of enantiomeric hetero-double-helices and aggregates from racemic oxymethylenehelicene oligomers.

A mixture of oxymethylenehelicene (P)-hexamer and (M)-hexamer in solution exhibited chiral symmetry breaking, which was induced by mechanical stirring, during the formation of enantiomeric hetero-double-helices and their aggregates. A racemic 50 : 50 mixture was heated to 90 °C to form a dissociated state, and then cooled to 25 °C. Mechanical stirring with a magnetic stirrer at 2000 rpm for 100 h resulted in the exhibition of a strong negative Cotton effect at 322 nm. Repeated experiments provided negative Cotton effects, which is due to the deterministic chiral symmetry breaking. No change in the Cotton effect occurred in the absence of stirring. The (P)-hexamer to (M)-hexamer mixing molar fraction was varied, and a positive Cotton effect appeared at molar fractions between 40 : 60 and 46 : 54 and a negative Cotton effect at molar fractions between 48 : 52 and 60 : 40, which was reversed at 47 : 53. The slight deviation of symmetry from that at 50 : 50 was termed proximate stochastic chiral symmetry breaking. The process of chiral symmetry breaking could be tuned by varying the procedures of mechanical stirring and mixing procedures for solutions of (P)-hexamer and/or (M)-hexamer.

A Greener Approach to Prepare Natural Deep Eutectic Solvents

AbstractNatural deep eutectic solvents (NADES) is one of the hottest issues in the field of green chemistry. However, it is possible to make them greener? Herein we propose a new microwave (MW) assisted preparation demanding only seconds. The MW‐NADES were challenged with those obtained by the classical Heating & Stirring procedure in terms of green analytical metrics and physical parameters. Indeed, the following analytical applications were tested: a) extraction media for phenolics and alkaloids from plant, b) enhancers for electrochemical detection of phenolic compounds. Our results demonstrate outstanding environmental advantages as the dramatic decrease of synthesis time (the shortest time to date, 60 minutes to 20 seconds) and energy consumption (650 times lower). The analytical performance and physicochemical parameters were comparable with the traditional NADES.

A simple polyethylenimine-salicylaldehyde fluorescence probe: sensitive and selective detection of Zn2+ and Cd2+ in aqueous solution by adding S2− ion

A novel polyethylenimine (PEI)-salicylaldehyde (SA) fluorescence probe, simply prepared by stirring procedure, can sensitively detect Zn2+ (25nM) and Cd2+ (10nM) in aqueous solution. Formation of metal-to-ligand complexes (Zn2+@PEI-SA and Cd2+@PEI-SA) between ions and Schiff base generate a new emission at 454nm, which increase with the concentration of the ions (turn-on). Furthermore, after adding S2− into the complexes, we can distinguish them due to the fluorescence quenching for Cd2+@PEI-SA (turn-off). Both response times for turning on and off the fluorescence are less than 1min.

EMPIRICAL EVALUATION OF STIRRING PROCEDURES IN THE PRODUCTION OF BIODIESEL FROM CASTOR OIL

Aiming to evaluate how stirring procedures impact biodiesel production from castor oil, this work employed a fractional factorial design to study the influence of some parameters on the alkaline catalytic transesterification of castor oil for biodiesel production. Biodiesel was produced in a pilot plant equipped with a stirring tank reactor and a thermostatic bath. The study used a 27-2 factorial design. The variables were stirring rate, presence or absence of deflection, impeller type, oil/methanol molar ratio, reaction time, temperature, and catalyst type. Gas chromatography afforded the reaction yields. Analysis of each variables as well as evaluation of binary interactions helped to determine how the parameters affected biodiesel production. The best conditions for a yield of 99.3 % were: turbine impeller, absence of deflection in the reactor, stirring rate of 500 rpm, 1:7 oil/alcohol molar ratio, sodium hydroxide as catalyst, reaction time of 30 min, and temperature of 50 °C.

DNA strand break dependence on Tris and arginine scavenger concentrations under ultra-soft X-ray irradiation: the contribution of secondary arginine radicals.

In this study, we used a bench-top cold-cathode ultra-soft X-ray (USX) generator to expose aqueous DNA plasmid solutions to low-LET radiation under various scavenging conditions. Single- and double-strand breaks were assessed using classic gel electrophoresis quantification of linear, circular and supercoiled plasmid DNA topologies. With their very low penetration range in water, USX can only interact with matter up to short distances, of the order of 50 μm. We validated a stirring procedure which makes it possible to expose 100 µL of aqueous samples (2 mm thick). The scavenging of OH radicals by Tris buffer was studied at ambient temperature under aerobic conditions and compared to data gathered in the literature. A very good agreement was found with the rare data dealing with DNA plasmid exposed to Al Kα photons at low temperature (T ≤ 277 K), which therefore validated the experimental procedure. The yields for DNA single-strand breaks determined during this study enabled the ratio of indirect to direct effects to be determined at 96.2%, in good agreement with the value of 97.7% stemming from a study based on γ-ray irradiation of frozen solutions of plasmid DNA. Then, arginine was used both to create a "biological-like" chemical environment around the DNA plasmids and as an OH radical scavenger, in vitro. Although arginine has a greater scavenging (protecting) power than Tris, surprisingly, it led to higher rates of strand breakage. Based on the specific binding modes of arginine to DNA, we suggest that the side effects observed are due to the presence of arginine near to, but also inside, the DNA double helix.

Zn–HA–TiO2 nanocomposite coatings electrodeposited on a NiTi shape memory alloy

In this work, zinc–hydroxyapatite (Zn–HA) and zinc–hydroxyapatite–titania (Zn–HA–TiO2) nanocomposite coatings were electrodeposited onto a NiTi shape memory alloy, using a chloride zinc plating bath. The structure of the composite coatings was characterized by X-ray diffraction, scanning electron microscopy and high-resolution transmission electron microscopy. According to the results, the Zn–HA–TiO2 coating exhibited a plate-like surface morphology, where the addition of the nanoparticles caused to an increase in roughness. It was also found that due to applying a proper stirring procedure during co-deposition, a homogenous dispersion of the nanoparticles in the coatings was achieved. Also, the addition of the TiO2 nanoparticles to the Zn–HA–TiO2 coating enhanced the microhardness and wear resistance. Copyright © 2014 John Wiley & Sons, Ltd.

A facile bio-replicated synthesis of SnO2 motifs with porous surface by using pollen grains of Peltophorum pterocarpum as a template

A bio-economical route for synthesizing highly crystalline SnO2 motifs with porous structures have been developed with the help of naturally obtained Peltophorum pterocarpum pollen grains. Fresh and dried pollen grains were directly used for the synthesis after rinsing with anhydrous ethanol. Stirring procedure with tin (IV) chloride pentahydrate solution followed by a suitable heat treatment provided a well-structured pollen morphology to the inorganic SnO2 motifs. The synthesized micro porous SnO2 motifs were characterized by DSC-TGA, XRD, UV–visible spectroscopy, SEM and TEM, BET and electron energy loss spectroscopy (EELS). The SnO2 motifs had a tetragonal rutile crystal structure and its maximum band gap was found to be 4.26 eV. The motifs were made up of SnO2 nanoparticles of size in the range from 16 to 25 nm as obtained from TEM analysis. The maximum BET surface area was found to be 82.72 m2g−1. The EELS analysis provided the elemental composition present in SnO2 motifs. A facile method for the production of micro porous SnO2 motifs along with their characteristics is elucidated in this report.