Characterization of Magnesium‐Doped Hydroxyapatite Prepared by Sol‐Gel Process

Pure and doped hydroxyapatite (HA) nanocrystalline powders (Ca_10‐xMg_x(PO₄)₆OH₂) were synthesized using sol‐gel process. For this, calcium nitrate tetrahydrate, magnesium nitrate hexahydrate, and phosphorous pentoxide were used as precursors for Ca, Mg, and P, respectively. Calculated amounts of magnesium ions (Mg⁺²) especially from 0 to 10% (molar ratio) were incorporated as dopant into the calcium sol solution. The structure and morphology of the gels obtained after mixing the phosphorous and (calcium + magnesium) sol solution were different, and their condensations in time depend on the quantities of magnesium added. The several powders resulting from the gels dried and sintered at 500°C for 1 h were characterized by thermogravimetry (TG), Fourier transform infrared spectroscopy (FTIR), X‐ray diffraction (XRD), and inductively coupled plasma (ICP). Additionally, their agglomeration, morphology, and particle size were investigated using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The specific surface area of each sample was measured by the Brunauer–Emmett–Teller (BET) gas adsorption technique. The results of XRD, FTIR, and ICP values ranged between 0.45 and 2.11 mg/L indicated that the magnesium added in the calcium solution was incorporated in the lattice structure of HA so prepared, while those obtained by SEM and TEM confirmed the influence of Mg on their morphology (needle and irregular shape) and crystallite size, which is about 30–60 nm. The as‐prepared powders had a specific surface area ranged between 6.37 and 27.60 m²/g.     

Thermal buckling behavior of two-dimensional imperfect functionally graded microscale-tapered porous beam

This article presents a study on the thermal buckling behavior of two-dimensional functionally graded microbeams made of porous materials. The material composition varies along thickness and length of the microbeam based on the power law distribution. The microbeam is modeled within the framework of Euler–Bernoulli beam theory. The microbeam is considered having variable material composition along thickness. The equations are derived using the modified couple stress theory and the solving process is based on the generalized differential quadrature method. The validity of the results is shown through comparison of the results with the results of other published research.     

Immobilization of glucose oxidase on 3D graphene thin film: Novel glucose bioanalytical sensing platform

Electrochemical biosensors are responsible for quantification of analytes for medical diagnostics applications. They are considered as a promising means to investigate the content of a biological sample owing to the direct exchange of a biological process to an electronic output signal. Novel characteristics of nanocarbon materials attracted much attention for fabrication of numerous electrochemical biosensors with developed analytical capacities. This paper aims to provide perceptions of 3D graphene-based electrochemical biosensors and to demonstrate its application in glucose detection. The developed glucose biosensing platform exhibits excellent catalytic activity towards glucose detection over a wide linear range of up to 6 mM with sensitivity of 1.63 μA mM^?1 cm^?2 and the stability of electrode is around 76.9% after one month. The facile and easy electrochemical approach used for the preparation of 3DG–GOD modified GCE may open up new horizons in the production of cost-effective biosensors.     

Immobilized copper ions on MWCNTS-Chitosan thin film: Enhanced amperometric sensor for electrochemical determination of diclofenac sodium in aqueous solution

A simple and effective electrochemical sensor was designed by the drop cast method for the detection of Diclofenac Sodium (DS), a widely used painkiller, by combining the significant catalytic property of multi-walled carbon nanotubes (MWCNTs), excellent adsorption capacity and film forming ability of Chitosan and synergistic catalytic effect of Chitosan-copper complex. The characteristics of newly proposed composite (MWCNTs/CTS-Cu/GCE) were investigated by different techniques like Fourier Transform Infrared Spectroscopy (FTIR), Field emission scanning electron microscopy (FESEM) and Energy dispersive X-ray analysis (EDX). The electrochemical performance of the newly modified composite was studied by using Cyclic voltammetry (CV), Electrochemical impedance spectroscopy (EIS), Square wave voltammetry (SWV). Under the optimum conditions, the anodic peak current for Diclofenac sodium (DS) was linear and the range is between 0.3 and 200 μmol L^?1 with the detection limit of 0.021 μmol L^?1 at pH 4.0. Finally, this modified composite exhibit good selectivity, sensitivity and stability for the detection of Diclofenac sodium (DS) from the pharmaceutical dosage form and real samples.     

Optimizing the formulation of a natural soft drink based on biophysical properties using mixture design methodology

Physical stability during storage is one of the main factors which affect drink quality and has undeniable effect on its marketing success. Whey protein drink sweetened with Iranian date syrup (DS), stabilized with soluble fraction of Persian gum (SFPG), fortified with caffeine and vitamin C was produced. Mixture design method was used to evaluate and optimize the combined effects of SFPG, DS and whey protein concentrate (WPC) as the main variable components on the biophysical properties of the drink. Serum separation, zeta-potential, microstructure and rheological characteristics were studied. SFPG showed the highest effect on the flow behavior index (n) and consistency coefficient (k) value of the drink. The minimum apparent viscosity belonged to the samples without SFPG and DS. The lowest serum separation occurred at maximum concentration of SFPG. Generally zeta-potential increased in the presence of SFPG significantly (P?<?0.05). Considering the results optimum values of SFPG, DS and WPC in the mixture design were predicted to be 1.5, 6.5 and 12%, respectively. Consistency coefficient, flow behavior index, apparent viscosity, serum separation, and zeta potential values of the optimized sample were 0.085 (Pa sⁿ), 0.7, 68.54 (Pa s), 3.9% and ??33 (mV), respectively.     

Tensile and water vapour properties of calcium‐crosslinked alginate‐cashew tree gum films

In this study, sodium alginate films were blended with cashew tree gum (CTG) and immersed in CaCl₂ solution. The influence of CTG concentration and immersion time in CaCl₂ on tensile properties, water vapour permeability and water solubility (WS) of alginate films was evaluated. Glycerol‐plasticized alginate/CTG films were cast on glass plates, which were then immersed in a 2% CaCl₂ solution to crosslink alginate. CTG concentration in the film solution and immersion time in CaCl₂ bath were varied according to a central composite design. Tensile strength, Young′s modulus, WS and water vapour barrier of the films were favoured by higher immersion times in CaCl₂ and lower CTG concentrations. The negative CTG effects on such properties have been attributed to competition between the polysaccharides for interactions with calcium ions, reducing crosslinking density and loosening the film structure. On the other hand, this loosening effect resulted in higher film flexibility at higher CTG concentrations.     

Improvement of electrical arc furnace operation with an appropriate model

Electrical arc furnaces are commonly employed in industry to produce molten steel by melting iron and scrap steel. Furnace control is a necessary operation for production optimization. The principal parameters to be controlled are: maximum productivity requirements, minimum power off time, good power quality and safety. The aim of this study is to achieve all these objectives. Hence, because of the stochastic and dynamic behaviour of the arc during the melting process, a proposed model is checked with measurements at an industrial electrical arc furnace. How electrodes position and transformer taps can affect X and R arc function are discussed in detail. This new operating strategy has been determined taking into account Flicker, melting stages and electrode positions. It is shown that optimum efficiency can be reached by the integration of the proposed model in regulation loop.     

Influence of processing on composition and antinutritional factors of chickpea protein concentrates produced by isoelectric precipitation and ultrafiltration

The effect of chickpea processing (i.e. defatting, isoelectric precipitation vs ultrafiltration/diafiltration) on the composition, protein recovery and antinutritional factors of protein concentrates was studied for two varieties (Mylese and Xena). Defatting did not affect significantly the content of antinutritional factors in the flours. However, production of concentrates from defatted flours by isoelectric precipitation resulted in higher phosphorous and phenolic contents compared to the concentrates produced by the same process using the full fat flours as starting material, while trypsin inhibitor content was not affected. When processed by ultrafiltration/diafiltration, protein concentrates produced from defatted flour showed a slightly lower trypsin inhibitor content than the ones produced from full fat flours in most cases, while the inverse was true for the phosphorous content, and for the phenolic content; this effect was a function of chickpea variety. Overall, UF pH 9/DF pH 6 resulted in concentrates with the lowest phosphorous content, while isoelectric precipitation and UF pH 9/DF pH 9 resulted in concentrates with lower phenolic content compared to the ones produced by UF pH 9/DF pH 6; for both processes the trypsin inhibitor content of the concentrates remained high.Industrial relevanceChickpea production is one of the major agricultural sectors of significant importance to Canada. Although chickpeas are grown in Canada for export, very little is exported in the value-added or processed form. Development of new extraction technologies and value-added products such as the ones presented in this paper is of interest for Canada since it would have a significant impact on the growth of the industry domestically, thus, creating opportunities to strengthen rural development in Canada. Successful implementation of these technologies would make interested Canadian companies viable competitors in the global plant protein production industry and would put Canada in a good position to enjoy a large share of this market both locally and internationally.More specifically, we are the first research group to compare the use of isoelectric precipitation and ultrafiltration/diafiltration for the production of chickpea protein concentrates from full fat and defatted flours of Kabuli and Desi chickpea variety, and to quantify the effect of these processes on the composition and on the antinutritional factors (i.e. phytic acid, total phenolics and trypsin inhibitors) of the resulting concentrates. Overall, it was observed that isoelectric precipitation was effective to an extent in producing concentrates with low phosphorous and phenolic contents. UF pH 9/DF pH 9 was also effective to an extent in producing concentrates with low phenolic content, while UF pH 9/DF pH 6 was more efficient in producing concentrates with low phosphorous content. High-quality chickpea protein concentrates with improved nutritional properties and good functional properties could beneficially be combined with other protein sources, such as soy protein, or be used in the formulation of foods, such as meat analogues, dairy, and bakery products.     

Composition and antimicrobial activity of essential oils of Cinnamosma fragrans

Essential oil samples of Cinnamosma fragrans from two regions in Madagascar, Tsaramandroso (38 samples) and Mariarano (30 samples), were analysed by GC/MS. Fifty-seven components were identified, accounting from 88.3% to 99.4% of the oils’ composition. The major components were linalool (72.5 ± 23.3%) in Tsaramandroso and 1,8-cineole (47.3 ± 10.2%) in Mariarano.     

A spatial kinetic model for simulating VVER-1000 start-up transient

An accurate prediction of reactor core behavior in transients depends on how much it could be possible to exactly determine the thermal feedbacks of the core elements such as fuel, clad and coolant. In short time transients, results of these feedbacks directly affect the reactor power and determine the reactor response. Such transients are commonly happened during the start-up process which makes it necessary to carefully evaluate the detail of process. Hence this research evaluates a short time transient occurring during the start up of VVER-1000 reactor. The reactor power was tracked using the point kinetic equations from HZP state (100 W) to 612 kW. Final power (612 kW) was achieved by withdrawing control rods and resultant excess reactivity was set into dynamic equations to calculate the reactor power. Since reactivity is the most important part in the point kinetic equations, using a Lumped Parameter (LP) approximation, energy balance equations were solved in different zones of the core. After determining temperature and total reactivity related to feedbacks in each time step, the exact value of reactivity is obtained and is inserted into point kinetic equations. In reactor core each zone has a specific temperature and its corresponding thermal feedback. To decrease the effects of point kinetic approximations, these partial feedbacks in different zones are superposed to show an accurate model of reactor core dynamics. In this manner the reactor point kinetic can be extended to the whole reactor core which means “Reactor spatial kinetic”. All required group constants in calculations are prepared using the WIMS code. In addition CITATION code was used to calculate the flux, power distribution and core reactivity inside the core. To update the last change in group constants and resultant reactivity in point kinetic equations, these neutronic codes were coupled with a developed dynamic program. This study is applied on a typical VVER-1000 reactor core to show the reactor response in short time transients caused during start-up procedure.