Combination Of Stirring Research Articles

Improvement of the Subcooling Problem of Sodium Acetate Trihydrate by a Combination of Stirring or Internal Electric Field and Nucleating Agent

Improvement of the Subcooling Problem of Sodium Acetate Trihydrate by a Combination of Stirring or Internal Electric Field and Nucleating Agent

Microencapsulation of Tecoma stans Extracts: Bioactive Properties Preservation and Physical Characterization Analysis.

Bioactive compounds from medicinal plants have applications in the development of functional foods. However, since they are unstable, encapsulation is used as a conservation alternative. This work aimed to assess the bioactive properties (antioxidant and hypoglycemic) of different extracts, including the infusion, as well as their spray-dried microencapsulates from Tecoma stans leaves. A factorial design was proposed to determine the best extraction conditions, based on ABTS and DPPH inhibition. Maltodextrin (MD), arabic gum (AG), and a 1:1 blend (MD:AG) were used as encapsulating agents. Moreover, characterization through physicochemical properties, gas chromatography/mass spectrometry (GC-MS) and scanning electron microscopy (SEM) of the best two powders based on the bioactive properties were analyzed. The results showed that the combination of stirring, water, and 5 min provided the highest inhibition to ABTS and DPPH (35.64 ± 1.25 mg Trolox/g d.s. and 2.77 ± 0.01 g Trolox/g d.s., respectively). Spray drying decreased the antioxidant activity of the extract while preserving it in the infusion. The encapsulated infusion with MD:AG had the highest hypoglycemic activity as it presented the lowest glycemic index (GI = 47). According to the results, the microencapsulates could potentially be added in foods to enhance nutritional quality and prevent/treat ailments.

Optimization and Characterization of Centrifugal-Cast Functionally Graded Al-SiC Composite Using Response Surface Methodology and Grey Relational Analysis

In this study, an optimization approach was employed to determine the optimal main parameters that improve the performance of functionally graded composites manufactured using a combination of stirring and horizontal centrifugal casting. Pure aluminum reinforced with silicon carbide particles was used as the material for the composites. The effects of key input parameters such as mold speed, pouring temperature, stirring speed, and radial distance were optimized using a combination of grey relational analysis and response surface methodology. The statistical significance of the predicted grey relational grade model was assessed through an analysis of variance to identify the appropriate main parameters. The results showed that radial distance had the greatest impact on the performance of the composites, followed by pouring temperature. The optimal combination of main parameters was determined to be a mold speed of 1000 rpm, a pouring temperature of 750 °C, a stirring speed of 150 rpm, and a radial distance of 1 mm. Confirmation tests using these optimal values resulted in a 54.69% improvement in the grey relational grade.

Magnetic resonance imaging spectrum of COVID-associated rhino-orbital-cerebral mucormycosis and assessment of anatomical severity.

To describe the extent and imaging findings of COVID-associated rhino-orbital-cerebral mucormycosis on magnetic resonance imaging and to evaluate the value of MRI severity score in grading the extent of involvement. Proven cases of ROCM with a history of concurrent or recently (<6weeks) treated COVID-19 underwent MRI at the initial presentation. Findings were charted for each anatomical structure and the extent of involvement was scored for sinonasal, extra-sinus soft tissues, orbits, and brain. MR severity score was defined by summing up the individual scores of each compartment (sinonasal 20, orbital 20, soft tissue 10, and brain 10) and a total score out of 60 was assigned. A total of 47 patients were included in our study with variable involvement of sinonasal compartment (n = 43), extra-sinus soft tissue (n = 25), orbits (n = 23), and brain (n = 17). In the sinonasal compartment, T2, DWI, and post-contrast T1 were the most useful sequences. A significantly higher mean sinonasal score was associated with mortality (p = 0.007). In the orbits, a combination of STIR (orbital fat and extraconal muscles), DWI (optic nerves), and post-contrast images (superior ophthalmic vein) were the most accurate sequences. A higher mean orbital score was associated with vision loss (p = 0.001). Patients with uncontrolled diabetes had greater extent of cranial involvement. A combination of magnetic resonance sequences is required to correctly evaluate the involvement of individual structures and thus to assign the correct MR scoring. The proposed MR severity score can effectively and objectively evaluate the severity of COVID-associated ROCM.

Magnetic Resonance Imaging in Paediatric Spinal Dysraphism with Comparative Usefulness of Various Magnetic Resonance Sequences.

Spinal dysraphism occurs due to failure of fusion of parts along dorsal aspect of midline structures lying along spinal axis from skin to vertebrae and spinal cord. Congenital spinal anomalies may be minimal and asymptomatic like spinal bifida occulta, or severe with marked neurological deficits like Arnold-Chiari malformation or caudal regression syndrome. Magnetic Resonance Imaging (MRI) is the modality of choice to diagnose mild to severe spinal dysraphism. To diagnose type and extent of clinically suspected spinal anomalies by MRI scan and to compare various sequences for identifying neural tissue and fatty tissue in anomalies. Fifty paediatric patients referred with clinical suspicion of spinal anomalies for MRI scan to radiodiagnosis department and diagnosed as having spinal dysraphism on 1.5 Tesla MRI Scan, were included in this observational analytic study. Various MRI sequences were taken in multiple planes. MRI findings of spinal dysraphism were compared with detailed clinical examination or surgical findings. Osseous anomalies like spina bifida occulta were confirmed by radiographs or CT scan. Out of 50 patients, type II Arnold-Chiari Malformation (34%), Spina Bifida Occulta (22%) and Diastematomyelia (18%) were common anomalies. MRI findings were well correlated with surgical findings in 20 operated cases. Nerve roots with/ without neural placode in thecal sac/outpouching were detected in combination of 3D HASTE myelographic sequence with SE/ TSE T1W sequence in 24 cases; which was significantly high as compared to combinations of SE/TSE T1W sequence with TSE T2W, with STIR and with Single Shot Myelographic sequence {p-value 0.002, < 0.001 and 0.008 respectively}. Fatty component was present in dysraphism in five cases, commonly as isolated anomaly; which was detected by combination of STIR and SE/TSE T1W sequences in all five cases. Paediatric spinal dysraphism and associated malformations are accurately diagnosed on MRI scan. MR myelographic 3D-HASTE and STIR sequences should be a part of protocol to evaluate spinal dysraphism.

IR spectroscopic analyses of amyloid fibril formation of β2-microglobulin using a simplified procedure for its in vitro generation at neutral pH

β2-microglobulin (β2m) is known to be the major component of fibrillar deposits in the joints of patients suffering from dialysis-related amyloidosis. We have developed a simplified procedure to convert monomeric recombinant β2m into amyloid fibrils at physiological pH by a combination of stirring and heating, enabling us to follow conformational changes associated with the assembly by infrared spectroscopy and electron microscopy. Our studies reveal that fibrillogenesis begins with the formation of relatively large aggregates, with secondary structure not significantly altered by the stirring-induced association. In contrast, the conversion of the amorphous aggregates into amyloid fibrils is associated with a profound re-organization at the level of the secondary and tertiary structures, leading to non-native like parallel arrangements of the β-strands in the fully formed amyloid structure of β2m. This study highlights the power of an approach to investigate the formation of β2m fibrils by a combination of biophysical techniques including IR spectroscopy.

Removal of cadmium from aqueous medium under ultrasound assistance using olive leaves as sorbent

In this work, the leaves of olive tree ( Olea europaea) are proposed as a novel low-cost non-conventional sorbent for the removal of cadmium from aqueous solutions with and without the assistance of ultrasound and by associating simultaneously ultrasonic irradiation and stirring. Sorption kinetics and isotherms were investigated. The operating variables studied were initial cadmium concentration, sorbent dosage, temperature and ultrasonic power. The sorption was significantly increased in the presence of ultrasound. The amount of cadmium sorption with the assistance of ultrasound was improved with the increase of sorbate initial concentration and temperature, and with the decrease of sorbent dosage. The acoustic power was an important factor for the enhancement of the removal of cadmium. The combination of stirring and ultrasound leads to an intensification of the removal of cadmium. Sorption isothermal data could be well simulated by Freundlich model, and then Temkin and Langmuir models. Langmuir simulation showed that the monolayer sorption capacities of olive leaves were 42.19, 55.87 and 64.94 mg g −1 for the conventional method, the ultrasound-assisted method and the combined method, respectively. The kinetic data fitted very well the pseudo-second-order kinetic model.

Ultrasound-assisted removal of malachite green from aqueous solution by dead pine needles

The dead needles of Aleppo pine (Pinus halepensis) were tested as a possible sorbent for the removal of malachite green from aqueous solutions in the absence and presence of ultrasound. Batch process was employed for sorption kinetic and equilibrium studies. Sorption experiments indicated that the sorption capacity was dependent of operating variables. Both the rate and the amount of malachite green sorption are markedly increased in the presence of the ultrasonic field. The dye removal with the assistance of ultrasound was enhanced with the increase of sorbate initial concentration and temperature, and with the decrease of sorbent dosage and ionic strength. The combination of stirring and ultrasound leads to an improvement of the removal of dye. The sorption kinetics was controlled by the intraparticle diffusion. The intraparticle diffusion coefficient increased 1.7 times in the presence of ultrasound and up to 3.6 times in the combined process. The sorption capacity, estimated according to the Freundlich model, indicates that ultrasound enhanced the sorption properties of the sorbent. The effect of ultrasound on the improvement of dye sorption is due to a variety of physical and mechanical effects as well as to thermal properties. The combination of ultrasound and stirring for the sorption process was shown to be of interest for the treatment of wastewaters contaminated with malachite green.

Crude oil contaminated soil washing in air sparging assisted stirred tank reactor using biosurfactants

This study investigated the removal of crude oil from soil using air sparging assisted stirred tank reactors. Two surfactants (rhamnolipid and sodium dodecyl sulfate, SDS) were tested and the effects of different parameters (i.e. temperature, surfactant concentrations, washing time, volume/mass ratio) were investigated under varying washing modes namely, stirring only, air sparging only and the combination of stirring and air sparging. The results showed that SDS removed more than 80% crude oil from non-weathered soil samples, whist rhamnolipid showed similar oil removal at the third and fourth levels of the parameters tested. The oil removal ability of the seawater prepared solutions were better than those of the distilled water solutions at the first and second levels of temperature and concentration of surfactant solutions. This approach of soil washing was noted to be effective in reducing the amount of oil in soil. Therefore we suggested that a field scale test be conducted to assess the efficiency of these surfactants.

The Effects of Surface Treatment for ZnS:Ag,Cl Using a Combination of Stirring and Ultrasonication in KOH Solutions

A commercially available blue emitting ZnS:Ag,Cl phosphor was surface-treated with a combination of stirring and ultrasonication in KOH solutions. The stirring and ultrasonication (SUST) enhanced the cathodoluminescence efficiency by 58%. From surface analyses, it was confirmed that ions were physisorbed on the surface of the phosphor, and they formed an additional electrical field on the surface into the E-beam induced field present in cathodoluminescent mode of operation. We observed that the maximum increase of phosphor efficiency at low applied voltages was around 800 V, that the recombination rate of the nonequilibrium charge carriers increased over two times, and that the diffusion-drift length was reduced after SUST. This can be explained by the formation of the increased electrical fields induced by physisorbed ions on the phosphor surface. © 2004 The Electrochemical Society. All rights reserved.