ascorbic-acid and ceric-oxide

Rod-like CeO

Topics: Ascorbic Acid; Cerium; Luminescence; Luminescent Measurements; Luminol; Nanoparticles; Oxcarbazepine; Pharmaceutical Preparations

Topics: Acetaminophen; Ascorbic Acid; Cerium; Dopamine; Electrochemistry; Electrodes; Green Chemistry Technology; Hydrogen-Ion Concentration; Limit of Detection; Microwaves; Nanoparticles; Nanotechnology; Nanotubes, Carbon; Surface Properties; Time Factors; Uric Acid

Core-shell palladium cube@CeO

Topics: Alkaline Phosphatase; Ascorbic Acid; Benzidines; Catalysis; Cerium; Colorimetry; Coloring Agents; Enzyme Assays; Limit of Detection; Metal Nanoparticles; Oxidation-Reduction; Palladium

The present work reports a study of the electrocatalytic activity of CeO2 nanoparticles and gold sononanoparticles (AuSNPs)/CeO2 nanocomposite, deposited on the surface of a Sonogel-Carbon (SNGC) matrix used as supporting electrode and the application of the sensing devices built with them to the determination of ascorbic acid (AA) used as a benchmark analyte. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were used to investigate the electrocatalytic behavior of CeO2- and AuSNPs/CeO2-modified SNGC electrodes, utilizing different concentrations of CeO2 nanoparticles and different AuSNPs:CeO2 w/w ratios. The best detection and quantification limits, obtained for CeO2 (10.0 mg·mL(-1))- and AuSNPs/CeO2 (3.25% w/w)-modified SNGC electrodes, were 1.59 × 10(-6) and 5.32 × 10(-6) M, and 2.93 × 10(-6) and 9.77 × 10(-6) M, respectively, with reproducibility values of 5.78% and 6.24%, respectively, for a linear concentration range from 1.5 µM to 4.0 mM of AA. The electrochemical devices were tested for the determination of AA in commercial apple juice for babies. The results were compared with those obtained by applying high performance liquid chromatography (HPLC) as a reference method. Recovery errors below 5% were obtained in most cases, with standard deviations lower than 3% for all the modified SNGC electrodes. Bare, CeO2- and AuSNPs/CeO2-modified SNGC electrodes were structurally characterized using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). AuSNPs and AuSNPs/CeO2 nanocomposite were characterized by UV-vis spectroscopy and X-ray diffraction (XRD), and information about their size distribution and shape was obtained by transmission electron microscopy (TEM). The advantages of employing CeO2 nanoparticles and AuSNPs/CeO2 nanocomposite in SNGC supporting material are also described. This research suggests that the modified electrode can be a very promising voltammetric sensor for the determination of electroactive species of interest in real samples.

Topics: Ascorbic Acid; Beverages; Calibration; Carbon; Catalysis; Cerium; Electrochemistry; Electrodes; Gels; Gold; Humans; Infant; Malus; Metal Nanoparticles; Reproducibility of Results; Spectrometry, X-Ray Emission; Spectrophotometry, Ultraviolet; Ultrasonics; X-Ray Diffraction

Previous studies have reported the uptake of cerium oxide nanoparticles (nCeO2) by plants, but their physiological impacts are not yet well understood. This research was aimed to study the impact of nCeO2 on the oxidative stress and antioxidant defense system in germinating rice seeds. The seeds were germinated for 10 days in nCeO2 suspension at 62.5, 125, 250, and 500 mg L(-1) concentrations. The Ce uptake, growth performance, stress levels, membrane damage, and antioxidant responses in seedlings were analyzed. Ce in tissues increased with increased nCeO2 concentrations, but the seedlings showed no visible signs of toxicity. Biochemical assays and in vivo imaging of H2O2 revealed that, relative to the control, the 62.5 and 125 mg nCeO2 L(-1) treatments significantly reduced the H2O2 generation in both shoots and roots. Enhanced electrolyte leakage and lipid peroxidation were found in the shoots of seedlings grown at 500 mg nCeO2 L(-1). Altered enzyme activities and levels of ascorbate and free thiols resulting in enhanced membrane damage and photosynthetic stress in the shoots were observed at 500 mg nCeO2 L(-1). These findings demonstrate a nCeO2 concentration-dependent modification of oxidative stress and antioxidant defense system in rice seedlings.

Topics: Antioxidants; Ascorbic Acid; Cerium; Chlorophyll; Electrolytes; Fluorescence; Germination; Hydrogen Peroxide; Image Processing, Computer-Assisted; Lipid Peroxidation; Nanoparticles; Oryza; Oxidative Stress; Plant Roots; Plant Shoots; Seedlings

Envirox is a scientifically and commercially proven diesel fuel combustion catalyst based on nanoparticulate cerium oxide and has been demonstrated to reduce fuel consumption, greenhouse gas emissions (CO(2)), and particulate emissions when added to diesel at levels of 5 mg/L. Studies have confirmed the adverse effects of particulates on respiratory and cardiac health, and while the use of Envirox contributes to a reduction in the particulate content in the air, it is necessary to demonstrate that the addition of Envirox does not alter the intrinsic toxicity of particles emitted in the exhaust. The purpose of this study was to evaluate the safety in use of Envirox by addressing the classical risk paradigm. Hazard assessment has been addressed by examining a range of in vitro cell and cell-free endpoints to assess the toxicity of cerium oxide nanoparticles as well as particulates emitted from engines using Envirox. Exposure assessment has taken data from modeling studies and from airborne monitoring sites in London and Newcastle adjacent to routes where vehicles using Envirox passed. Data have demonstrated that for the exposure levels measured, the estimated internal dose for a referential human in a chronic exposure situation is much lower than the no-observed-effect level (NOEL) in the in vitro toxicity studies. Exposure to nano-size cerium oxide as a result of the addition of Envirox to diesel fuel at the current levels of exposure in ambient air is therefore unlikely to lead to pulmonary oxidative stress and inflammation, which are the precursors for respiratory and cardiac health problems.

Topics: Adenosine Triphosphate; Animals; Antioxidants; Ascorbic Acid; Catalysis; Cell Line; Cerium; Environmental Pollutants; Epithelial Cells; Gasoline; Glutathione; Glutathione Peroxidase; Humans; Interleukin-8; Lung; Nanoparticles; Oxidation-Reduction; Particle Size; Particulate Matter; Rats; Risk Assessment; Superoxide Dismutase; Time Factors; Tumor Necrosis Factor-alpha; Vehicle Emissions