CHAMOMILE (Matricaria recutita) EXTRACT AS A CORROSION INHIBITOR FOR MILD STEEL IN HYDROCHLORIC ACID SOLUTION

The corrosion inhibition of mild steel in hydrochloric acid solution by chamomile (Matricaria recutita) extract (CE) was investigated through electrochemical (polarization, EIS) and surface analysis (optical microscopy/AFM/SEM) techniques. The effects of inhibitor concentration, temperature, and pH were evaluated. Thermodynamic parameters were calculated and adsorption studies were carried out. Finally, the surface morphology was investigated. The electrochemical studies showed that CE acts as a mixed-type corrosion inhibitor with predominantly anodic behavior. CE was adsorbed physically on the metal surface and obeyed the Langmuir adsorption isotherm. It impeded the corrosion processes by changing the activation energy. In the presence of CE, the metal surface was more uniform than the surface in the absence of inhibitor. Maximum inhibition efficiency (IE) was 93.28%, which was obtained at 22°C in 7.2 g/L of inhibitor in 1 M HCl solution.     

Development of a microfluidic-chip system based on parallel flow for intensified Gd(III) extraction from nitrate media using cationic extractant

Microfluidic solvent extraction (micro SX) of gadolinium was conducted using a mono- and di-ester mixture (MDEHPA) as the cationic extractant. A microfluidic YY channel was fabricated using CO₂-laser technique in a glass microchip used as the extraction system. Compared with batch extraction, extraction kinetic is found fast, and extraction equilibrium is attained within 15 s. Stoichiometry of the extracted complex is found to be Gd(NO₃)₃·3MDEHPA using log–log plot method. Additionally, the operating parameters and overall volumetric mass transfer coefficient $\left(k_{\mathrm{L}}\alpha \right)$ were investigated to determine the mass transfer performance. Optimal condition of microextraction for gadolinium using response surface methodology was determined (feed solutions 31 mg/L adjusted to pH value 2.5, extractant concentration 2.9 vol% and extraction time 13.5 s). In optimal condition, gadolinium extraction yield is obtained 95.5%. Findings of this study approve simplicity, portability, effectiveness, swiftness, and environmental friendliness microfluidic solvent extraction process and reveal that micro SX is useful in the field of extraction strategic metals present at low concentrations, which are otherwise not technically amenable or economically feasible to extract using current traditional methods.     

Local RBF-DQ method for two-dimensional transient heat conduction problems

The meshless local radial basis function-based differential quadrature (RBF-DQ) method is applied on two-dimensional heat conduction for different irregular geometries. This method is the combination of differential quadrature approximation of derivatives and function approximation of radial basis function. Four different geometries with regular and irregular boundaries are considered, and numerical results are compared with those gained by finite element (FE) solution achieved by COMSOL commercial code. Outcomes prove that current technique is in very good agreement with FEM and this fact that RBF-DQ method is an accurate and flexible method in solution of heat conduction problems.     

A new long term load management model for asset governance of electrical distribution systems

Long term load management (LTLM) is one of the key factors in making decisions regarding new investments in distribution systems. However, none of the previous studies have investigated the effect of external factors such as governance, urban planning and social behavior factors on LTLM. In this paper, a new LTLM model is proposed to determine the influence of external factors on LTLM. Distribution system development indices have been used to obtain asset governance targets; these indices can help Distribution Companies (DISCOs) compromise between reliability and running the system economically. Capacity utilization and the number of maneuver points are used here to do LTLM and improve asset governance. Numerical studies on a real distribution system (city with population about 200,000) have been conducted and sensitivity analysis of maneuver points and capacity utilization level with respect to external factors is studied and analyzed. The results show the feasibility of the proposed LTLM to obtain higher efficiency from the viewpoint of cost and quality service compared to conventional LTLM.     

Effect of TiO2 addition on microstructure and mechanical properties of alumina-based cores prepared by sol-gel method

Alumina-based ceramic cores have widespread applications especially in the investment casting of turbine blades due to chemical inertness with most of the superalloys, capability of machining in the green state, and their mechanical stability at high temperatures. The present work studied the effects of TiO₂ addition to the alumina-based cores. These cores were prepared via the sol-gel method process by mixing alumina powders with NH₄Cl and silica sol. The effects of adding different amounts of titania from 5 to 30 wt% and different sintering procedures on mechanical, physical, thermal, chemical, and microstructural features of the bodies were investigated. According to the results of rheology measurements of the slurries and flexural strength of the green bodies, the suitable amount of solid loading was 45 vol. %. The results showed that there is an optimum content for TiO₂ addition. The specimen contained 15 wt. % titania and sintered at 1400°C for 2 hours had the thermal expansion coefficient as low as 4.8 × 10⁻⁶/°C (25-900°C), suitable mechanical properties as a result of tialite formation, and apparent porosity of 28 vol. %, respectively. The result of creep deformation test showed that this specimen had near zero deformation at 1650°C.     

Antioxidant and antifungal activities of a new chemovar of cumin (Cuminum cyminum L.)

Food Science and Biotechnology - Chemical composition, antifungal and antioxidant properties of essential oil extracted from Cuminum cyminum from Iran was studied. GC–MS analysis revealed the...     

Activated carbon nanofibers as an alternative cathode catalyst to platinum in a two-chamber microbial fuel cell

This paper evaluated the oxygen reduction reaction (ORR) in a microbial fuel cell (MFC) system by using chemically and physically activated electrospun carbon nanofibers (ACNFs) in an MFC and comparing their performance with that of plain carbon paper. The chemical and physical activation was carried out by KOH reagents and CO₂ gas to increase the electrode surface area and the catalytic activity. As a result, it was found that the MFC with the chemically activated carbon nanofibers (ACNFs) exhibited better catalytic activity than that of the physically activated ACNFs. Chemically ACNFs with 8 M KOH were found to be one of the most promising candidates for the ORR and could generate up to 3.17 times more power than that of the carbon paper. The ACNFs with 8 M KOH exhibited 78% more power generation than that of the physically activated ACNFs and exhibited 16% more power generation than the chemically activated ACNFs with 4 M KOH. The power per cost of ACNFs with 8 M KOH is 2.65 times greater than that of the traditionally used platinum cathode. Thus, ACNFs are a good alternative catalyst to Pt for MFCs.     

Fabrication of Novel Membranes for Biomedical Applications via Halidation of Poly(Methacrylic Acid‐co‐Methyl Methacrylate) and Crosslinking of Complementary Groups by PEG

Fabrication of novel, biocompatible and stimuli‐responsive membranes based on the crosslinking of poly(methacrylic acid‐co‐methyl methacrylate) using polyethylene glycol as a crosslinking agent is accomplished in a two‐stage procedure. Membranes are fabricated by casting and curing of the reactive precursors in different reaction compositions and durations according to a three‐level factorial design‐of‐experiments. The resulting membranes were thoroughly characterized using SEM, FTIR spectroscopy, thermal analysis and swelling experiments. The thermal properties were improved and swelling behavior of the hydrogels assures its stimuli‐responsive nature. MTT‐assay and cytotoxicity evaluations of the fabricated membranes elucidate acceptable biocompatibility profiles.     

Comparison of essential oil compositions of Salvia mirzayanii obtained by supercritical carbon dioxide extraction and hydrodistillation methods

Essential oil of Salvia mirzayanii cultivated in Iran was obtained by hydrodistillation and supercritical (carbon dioxide) extraction methods. The oil was analysed by capillary gas chromatography using flame ionization and mass spectrometric detections. The compounds were identified according to their retention indices and mass spectra (EI, 70 eV). The effects of different parameters such as pressure, temperature, modifier volume and extraction times (dynamic and static) on the supercritical fluid extraction (SFE) of S. mirzayanii oil were investigated. The results showed that, under a pressure of 35.5 MPa, temperature of 35 °C, 6% methanol, dynamic extraction time of 50 min and static extraction time of 30 min, extraction was more selective for the linalyl acetate. Thirty four compounds were identified in the hydrodistilled oil. The major components of S. mirzayanii were linalyl acetate (7.6%), 1,8-cineole (8.0%), linalool (9.0%) and 8-acetoxy linalool (11.0%). However, by using supercritical carbon dioxide in optimum conditions, only three components contain more than 63% of the oil. The yield of the obtained oil based on hydrodistillation was 2.20% (v/w). Extraction yield based on the SFE varied in the range of 1.50–9.67% (w/w) under different conditions. The results revealed that, in Iranian S. mirzayanii oil, linalyl acetate is a major component.