Removal of Diazinon from aqueous solution by electrocoagulation process using aluminum electrodes

Electrocoagulation (EC) is an electrochemical method to treat polluted wastewaters and aqueous solutions. In this paper, the removal of Diazinon was studied by EC on aluminum electrode. The effect of several parameters such as initial concentration of Diazinon, current density, solution conductivity, effect of pH, and electrolysis time were investigated on EC performance. The obtained results showed that the removal efficiency of EC depends on the current density, initial concentration of Diazinon and electrolysis time. The optimum pH is 3 and also the solution conductivity has no significant effect on removal efficiency.     

LaMer diagram approach to study the nucleation and growth of Cu2O nanoparticles using supersaturation theory

Uptake to cuprous oxide (Cu₂O) nanoparticle synthesis with various particle sizes and shapes via supersaturation chemistry approach (LaMer model) has been conducted. Ascorbic acid and maltodextrine as reducing agents and polyvinylpyrrolidone (PVP) as a surfactant were utilized for synthesis of Cu₂O nanoparticles in aqueous solution. The narrow particle size range was achieved by controlling the kinetics of nucleation and growth of particles to satisfy LaMer theory. This mean was performed utilizing different reducing agents (ascorbic acid and maltodextrin) and also, changing the reducing agent addition condition. The results showed the reducing agent addition condition, varying the size of Cu₂O nanoparticles from 89 nm to 74 nm for drop-wisely and at-once routes, respectively. The samples were characterized by XRD, SEM, and UV-Vis spectroscopy. The results indicate the shape of as-prepared cuprous oxide nanoparticles have close relationship with thermodynamic and kinetic conditions, and also reducing addition condition.     

Bi-supported Ziegler–Natta TiCl4/MCM-41/MgCl2 (ethoxide type) catalyst preparation and comprehensive investigations of produced polyethylene characteristics

Bi-supported Ziegler–Natta catalysts (TiCl₄/MCM-41/MgCl₂ (ethoxide type)) were synthesized to improve the morphology and the properties of polyethylene. The morphology control is a crucial issue in polymerization process, while tailoring the properties of polymers is needed for specific applications. The catalysts were synthesized in different ratios of two supports with impregnation method. The polymerization process was carried out in atmospheric slurry reactor. The catalysts were characterized with scanning electron microscopy - energy dispersive X-ray spectroscopy (SEM–EDX), inductively coupled plasma, Fourier transform infrared spectrometry (FTIR), and Brunauer-Emmett-Teller (BET) methods. The polymers were analyzed with scanning electron microscopy (SEM), thermogravimetric analysis (TGA), differential scanning calorimetry, FTIR, and tensile-strength analyses. Ubbelohde viscometer and frequency sweep measurements showed that the synthesized polymers are ultra-high-molecular-weight polyethylene. Mechanical properties of polymers showed higher Young's modulus in samples containing MCM-41, having higher thermal stability supported by TGA analysis. SEM images of bi-supported catalyst showed a controlled spherical morphology with uniform size distribution. SEM analysis support that the polymers replicate their morphology from catalyst, improving their morphology comparing to MgCl₂-supported catalyst. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48553.     

Polyphenol-rich seaweed (Eucheuma cottonii) extract suppresses breast tumour via hormone modulation and apoptosis induction

The edible red seaweed Eucheuma cottonii is abundantly cultivated for carrageenan production. This study investigated the effects of dietary E. cottonii polyphenol-rich extract (ECME) on breast cancer. In vitro assays showed that ECME was antiproliferative against oestrogen-dependent MCF-7 and oestrogen-independent MB-MDA-231 human breast-cancer cells (IC₅₀ values of 20 and 42 μg/ml, respectively) but was non-toxic to normal cell lines. The ECME (150 and 300 mg/kg BW) was fed to female rats and, after 4 weeks, rat mammary tumour was induced using LA7 cells (inoculated subcutaneously). The ECME inhibited tumour development and erythrocyte lipid peroxidation in the cancer-induced rats, dose-dependently. It showed anti-oestrogenic effects on the rat estrous cycle and serum hormone levels. Electron microscopy and histopathology observations confirmed apoptosis in the rat mammary tumours. The polyphenol-rich ECME was tumour-suppressive via apoptosis induction, downregulating the endogenous oestrogen biosynthesis, and improving antioxidative status in the rats.     

Thermal,mechanical, and corrosion resistance properties of vinyl ester/clay nanocomposites for the matrix of carbon fiber‐reinforced composites exposed to electron beam

Vinyl ester/clay nanocomposites with 1, 3, and 5% nanoclay contents were prepared. X‐ray diffractography patterns and Scanning Electron micrographs showed that nanocomposites with the exfoliated structure were formed. Thermogravimetric analysis, water absorption test, and Tafel polarization method, respectively, revealed the improvements in thermal resistance, water barrier properties, and corrosion resistance properties of the samples with an increase in the amount of the incorporated nanoclay. Tensile tests showed that nanoclay also enhanced the mechanical properties of the polymer, so that the tensile strength of the samples with 5% nanoclay was more than 3 times higher than tensile strength of pure vinyl ester samples. Overall, the best properties were observed for the samples containing 5% nanoclay. Pure vinyl ester and nanocomposite with 5% nanoclay content were exposed to the electron beam radiation and their mechanical properties improved up to 500 kGy irradiation dose. Finally, pure vinyl ester and vinyl ester/nanoclay (5%) matrixes were reinforced with carbon fiber and the effect of electron beam irradiation on their mechanical properties was examined. The tensile strength and the modulus of the samples initially increased after exposure to the radiation doses up to 500 kGy and then a decrease was observed as the irradiation dose rose to 1000 kGy. Moreover, nanoclay moderated the effect of the irradiation. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42393.     

Radiosynthesis and biodistribution of [^18F]-tetracosactide using a semi-automated [^18F]SFB production module

In order to prepare a specific melanocortin type 2 receptor (MC2R) ligand, b1-24-corticotrophin was pre-pared in one-step reaction with [18F] SFB and b-1-24-corticotrophin pharmaceutical solution (1 mg/mL, pH=6.5). [18F]SFB was prepared in a semi-automated module in two steps with an overall radiochemical yield of 47% to EOB (not-decay corrected) in 90 min. The 18F-labeled intermediates and 18F-labeled peptide was checked by RTLC and HPLC. The results show that the radiochemical purity is >95% and the yield to EOB (not-decay corrected) is 29% for final 18F-labeled peptide at optimized conditions. Preliminary in vivo studies in normal mice were performed to deter-mine biodistribution of the 18F-labeled peptide for 150 min. The results show that the major tracer uptake is consistent with the natural distribution of MC2R receptors in mammals. Testes/blood and testes/muscle ratios for 18F-labeled peptide at 150 min were 184 and 1.56, respectively, and adipocyte/blood and adipocyte/muscle ratios at 120 min were 221 and 142, respectively. The data support the specific receptor binding of the radiolabeled peptide as reported for MC2R receptor accumulation in adipocytes and testes and demonstrates the retention of biological activity of the pep-tide. This tracer can be used in detection of MC2R distribution in malignancies and sex organ diseases.     

Quenching and Partitioning (Q&P) Processing of Martensitic Stainless Steels

Austenite was stabilized in the martensitic stainless steel grade AISI 420 by means of quenching and partitioning (Q&P) processing. The effects of quenching temperature on the microstructure and mechanical properties were investigated. The specimens processed at low quench temperatures (regime I) had a microstructure consisting of tempered martensite and retained austenite. At high quench temperatures (regime II), fresh martensite was present too. The highest austenite fraction of about 0.35 was obtained at the quench temperature delineating regimes I and II. The amount of carbon in retained austenite increased as the quench temperature decreased. The carbon level of austenite was, however, much lower than the carbon concentrations expected from full partitioning assumption. This was mainly due to the extensive cementite formation in the partitioning step. Stabilization of austenite by Q&P processing was found not to be purely chemical. Austenite stabilization was also assisted by locking, because of local carbon enrichment, of potential martensite nucleation sites in the austenite/martensite boundaries and in austenite defects. The importance of the latter stabilization mechanism increased at higher martensite fractions. According to the tensile test results, the Q&P processed specimen with the highest austenite fraction was not associated with the best combination of strength and ductility. The mechanical stability of austenite was found to increase with its carbon concentration being the highest at the lowest quench temperature. The thermal stability, on the other hand, was almost inversely proportional to the retained austenite fraction, being low at intermediate quench temperatures where the retained austenite fraction was high.     

Influences of feeding conditions and objective function on the optimal design of gas flow channel of a PEM fuel cell

Polymer electrolyte membrane fuel cell (PEMFC) is one of the promising electricity generating technologies with a wide range of applicability; however, it needs further improvements to be commercially viable. The design of a PEMFC plays a key role in its viability, and is often reduced to the design of gas flow channel (GFC) at the cathode side. In this study, it is attempted to figure out the optimal dimensions (i.e., width and height) of the rectangular cross sectional area of the cathode GFC of a PEMFC via numerical examination of various sets of dimensions. The optimization procedure is carried out for two different objective functions (the maximization of the maximum power and the maximization of the average power over a range of operating voltages) as well as for different sets of operating conditions (cell temperature, operating pressure, and stoichiometry and relative humidity of inlet gases). To the best of authors' knowledge, the following observations may be considered to be the contributions of the present work to the subject: First, the influence of cross sectional dimensions on the PEMFC performance is considerable, and this considerable influence is not limited to a specific set of operating conditions. Second, the performance of the PEMFC may both deteriorate and improve with the channel width or height, depending on its operating conditions as well as on its current dimensions. Third, there exists no single optimal cross section for different sets of operating conditions. Fourth, the polarization curves of two different cross sections may intersect, and as a result, one cross section may have a greater maximum power but at the same time lower average power in comparison to the other one. And fifth, among all the operating parameters, the relative humidity of inlet gases has the greatest effect on the optimal cross sectional dimensions.     

Effects of bed-load movement on flow resistance over bed forms

The effect of bed-load transport on flow resistance of alluvial channels with undulated bed was experimentally investigated. The experiments were carried out in a tilting flume 250mm wide and 12.5m long with glass-sides of rectangular cross-section and artificial dune shaped floor that was made from Plexi-glass. Steady flow of clear as against sediment-laden water with different flow depths and velocities were studied in the experiments with a fine sand (d ₅₀ = 0.5mm). The results indicate that the transport of fine particles (d ₅₀ = 0.5mm) can decrease the friction factor by 22% and 24% respectively for smooth and rough beds. Increasing the bed-load size (d ₅₀ = 2.84 mm) can decrease the friction factor by 32% and 39% respectively for smooth and rough beds. The decrease in flow resistance is due to filling up of the troughs of dunes. This separation zone is responsible for increasing the flow resistance. On the upstream side of dunes condition is similar to plane bed. Presence of bed-load causes to increase the shear velocity and hence increasing flow resistance. But decreasing in flow resistance is more and it causes to decrease the total flow resistance. Grains saturated the troughs in the bed topography, effectively helping in smoothening of bed irregularities.