Residues of ¹4C-ethion along the extraction and refining process of maize oil, and the bioavailability of bound residues in the cake for experimental animals.

Maize seeds obtained from ¹4C-ethion treated plants contained about 0.01 % of the originally applied radioactivity 1 month following the last pesticide application. Hexane and methanol extracts of the seeds accounted for 35 % and 22.5 % of the radioactive residues, respectively, with 40 % remaining in the seed cake. Commercial processing procedures resulted in a gradual decrease in the total amount of ¹4C-residues in oils with aged residues. The refined oil contained ¹4C-residues that amounted to about 30 % of the amount that was originally present. The major residues in processed oil are ethion monooxon, O,O-diethyl phosphorothioate and O,O-diethyl S-hydroxymethyl phosphorodithioate, in addition to one unknown compound. After feeding rats with the cake containing ethion bound residues, a substantial amount (71 %) of ¹4C-residues was eliminated in the urine, while about 12 % was excreted in the feces. About 5 % of the radioactive residues were distributed among various organs. The bound residue was quite readily bioavailable to the rats.

Tungsten carbide@graphene nanoflakes: Preparation, characterization and electrochemical activity for capacitive deionization technology.

In this present work, tungsten carbide (WC) nanoparticles were intercalated between graphene nanoflakes (GNFs) using sonication followed by hydrothermal treatment. Pristine WC, GNFs and a series of WC@GNFs nanomaterials were physically characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET) and water contact angle measurements. Cyclic voltammetry and electrochemical impedance studies were operated to investigate the electrochemical performance of these nanocomposites as efficient capacitive deionization (CDI) electrodes with improved electrochemical characteristics and specific capacitances in NaCl solution. Among the synthesized nanomaterials, WC@GNFs containing 10% WC displayed appreciable specific capacitance [580.00 F g-1], salt removal efficiency [95.50%], electrosorptive capacity [22.155 mg g-1] and charge efficiency [0.356] values. Accordingly, the measured results in this study indicate that WC@GNFs nanomaterials are suitable electrodes with an easy preparation route for efficient CDI technology.

Influence of support material on the electrocatalytic activity of nickel oxide nanoparticles for urea electro-oxidation reaction.

Nickel oxide nanoparticles were deposited on different carbon supports including activated Vulcan XC-72R carbon black (NiO/AC), multi-walled carbon nanotubes (NiO/MWCNTs), graphene (NiO/Gr) and graphite (NiO/Gt) through precipitation step followed by calcination at 400 °C. To determine the crystalline structure and morphology of prepared electrocatalysts, X-ray diffraction (XRD) and transmission electron microscopy (TEM) were employed. The electrocatalytic activity of NiO/carbon support electrocatalysts was investigated towards urea electro-oxidation reaction in NaOH solution using cyclic voltammetry, chronoamperometry and electrochemical impedance spectroscopy. Urea oxidation peak current density was increased in the following order: NiO/AC < NiO/MWCNTs < NiO/Gr < NiO/Gt. Chronoamperometry test also showed an increased steady state oxidation current density for NiO/Gt in comparison to other electrocatalysts. The increased activity and stability of NiO/Gt electrocatalyst encourage the application of graphite as an efficient and cost-saving support to carry metal nanoparticles for urea electro-oxidation reaction.

Enhanced ethanol electro-oxidation reaction on carbon supported Pd-metal oxide electrocatalysts.

Various Pd-metal oxide/C electrocatalysts were fabricated using ethylene glycol as a reducing agent in modified microwave-assisted polyol process. The crystal structure and surface morphology were studied using X-ray diffraction and transmission electron microscopy. All prepared Pd-metal oxide/C electrocatalysts exhibited a shift of Pd diffraction planes in the positive direction in relation to that of Pd/C. Highly dispersed palladium nanoparticles were formed on different metal oxide/C supports. The electrocatalytic performance of these electrocatalysts for ethanol oxidation was examined in NaOH solution using cyclic voltammetry, chronoamperometry and electrochemical impedance spectroscopy. An improvement in electrochemical parameters including onset potential, oxidation current density and If/Ib values was recorded at different Pd-metal oxide/C electrocatalysts, especially Pd-NiO/C. Three folds increment in steady state oxidation current density value was also displayed by investigated Pd-metal oxide/C electrocatalysts when contrasted to that of Pd/C to reflect their enhanced stability behavior.

NiO nanoparticles on graphene nanosheets at different calcination temperatures as effective electrocatalysts for urea electro-oxidation in alkaline medium.

NiO nanoparticles were supported on graphene nanosheets (NiO/Gr) through coprecipitation step of Ni(OH)2 species, followed by calcination at different temperature values. The formed nanocomposites were characterized by employing X-ray diffraction (XRD) and transmission electron microscopy (TEM) to investigate their crystalline structure and morphology. The effect of varying the calcination temperature during the preparation of NiO/Gr electrocatalyst on some kinetic parameters in 0.5M NaOH solution was studied. The electrocatalytic activity of synthesized electrocatalysts was examined for urea electro-oxidation reaction in alkaline solution using cyclic voltammetry, chronoamperometry and electrochemical impedance spectroscopy. Among the fabricated NiO/Gr electrocatalysts, the one that was heated at 200°C exhibited the highest urea oxidation current density value with most stable performance for long time.

Amperometric glucose sensor based on nickel nanoparticles/carbon Vulcan XC-72R.

A stable non-enzymatic glucose sensor was constructed by chemical deposition of nickel nanoparticles on carbon Vulcan XC-72R using microwave irradiation technique. The mode and time of microwave irradiation during nickel salt reduction were varied. This was found to affect the morphology of formed Ni/C powder as evidenced by TEM analysis. Nickel nanoparticles aggregation becomes more serious at longer microwave irradiation times. The electrocatalytic activity of different Ni/C samples towards glucose oxidation was studied in KOH solution by employing cyclic voltammetry and chronoamperometry techniques. Ni/C sample, prepared by pulse mode with total operating time of 150s, showed the highest oxidation current density. An excellent sensitivity value of 1349.7µAmM(-1)cm(-2) with a detection limit of 0.232µM was gained by Ni/C sensor. It also exhibits good reproducibility and long-term stability, as well as high selectivity with insignificant interference from ascorbic acid.

Development of Cu2O/Carbon Vulcan XC-72 as non-enzymatic sensor for glucose determination.

A novel and stable non-enzymatic glucose sensor was developed based on the chemical reduction of Cu(2)O nanoparticles on Carbon Vulcan XC-72 using NaBH(4) as the reducing agent via the impregnation method. Different molar ratios of NaBH(4) to the copper salt were employed during the reduction step. This was found to affect the morphology; composition and structure of the prepared samples as investigated by TEM, EDX and XRD analyses. Cyclic voltammetry and chronoamperometry were applied to examine the electrocatalytic activity of the different samples of Cu(2)O/Carbon Vulcan XC-72 towards glucose oxidation in alkaline medium. The 'x70' sample got the highest oxidation current density and the lowest oxidation potential. The performance of this sensor was evaluated showing a wide linear range up to 6mM with sensitivity of 629 µA cm(-2)mM(-1) and detection limit of 2.4 µM. Its good tolerance to ascorbic acid with long-term stability elects Cu(2)O/Carbon Vulcan XC-72 as a promising glucose sensor.