Lanthanum Ferrite Ceramic Powders: Synthesis, Characterization and Electrochemical Detection Application

The perovskite-type lanthanum ferrite, LaFeO3, has been prepared by thermal decomposition of in situ obtained lanthanum ferrioxalate compound precursor, LaFe(C2O4)3·3H2O. The oxalate precursor was synthesized through the redox reaction between 1,2-ethanediol and nitrate ion and characterized by chemical analysis, infrared spectroscopy, and thermal analysis. LaFeO3 obtained after the calcination of the precursor for at least 550–800 °C/1 h have been investigated by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), and high-resolution transmission electron microscopy (HRTEM). A boron-doped diamond electrode (BDD) modified with LaFeO3 ceramic powders at 550 °C (LaFeO3/BDD) by simple immersion was characterized by cyclic voltammetry and tested for the voltammetric and amperometric detection of capecitabine (CCB), which is a cytostatic drug considered as an emerging pollutant in water. The modified electrode exhibited a complex electrochemical behaviour by several redox systems in direct relation to the electrode potential range. The results obtained by cyclic voltammetry (CV), differential-pulsed voltammetry (DPV), and multiple-pulsed amperometry proved the electrocatalytic effect to capecitabine oxidation and reduction and allowed its electrochemical detection in alkaline aqueous solution.

Structure and properties of nanocrystalline tetragonal BaTiO3 prepared by combustion solid state synthesis

Barium titanate (BaTiO3) attracts high scientific and technological attention due to good dielectric and electromechanical properties. Although BaTiO3 is one of the most frequently investigated ferroelectric materials, the need for finding new and/or improved synthesis methods of this material still exists. In this paper, a novel, mild synthesis route for producing tetragonal BaTiO3 from barium nitrate and Ti-oxalate precursor is presented. Morphology of the prepared and subsequently sintered BaTiO3 was determined by SEM. Particle size distribution of the as prepared powder was monitored by the laser diffraction. The phase composition, structure and lattice dynamics were investigated by XRD and Raman spectroscopy. Finally, dielectric parameters were determined in the temperature range from 30 to 180?C, and within a variety of frequencies. Curie temperature was detected at 130?C.

Diet-induced oxalate nephropathy

Oxalate nephropathy is a rare condition and may be overlooked due to lack of recognition and understanding of triggers. An 81-year-old man was sent to nephrologist because of significantly increased creatinine (1.5–1.9 mg/dL) noted for 3 months. He had well-controlled diabetes but no history of kidney disease. He had no chronic diarrhoea or intestinal surgery. He was a health-minded individual who had read extensively about benefit of antioxidants. Initial work-up was unrevealing. Within a few weeks after first visit, he developed acute symptomatic worsening kidney injury with nausea, vomiting and creatinine up to 6.8 mg/dL. Repeat examination of the urine sediment revealed casts containing calcium oxalate crystals. A deeper dietary history revealed widespread oxalate precursor consumption. A kidney biopsy confirmed oxalate nephropathy. Restriction of oxalate consumption combined with adequate hydration, oral calcium acetate resulted in partial renal recovery without need for haemodialysis.

Preparation of Iron Carbides Formed by Iron Oxalate Carburization for Fischer–Tropsch Synthesis

Different iron carbides were synthesized from the iron oxalate precursor by varying the CO carburization temperature between 320 and 450 °C. These iron carbides were applied to the high-temperature Fischer–Tropsch synthesis (FTS) without in situ activation treatment directly. The iron oxalate as a precursor was prepared using a solid-state reaction treatment at room temperature. Pure Fe5C2 was formed at a carburization temperature of 320 C, whereas pure Fe3C was formed at 450 °C. Interestingly, at intermediate carburization temperatures (350–375 °C), these two phases coexisted at the same time although in different proportions, and 360 °C was the transition temperature at which the iron carbide phase transformed from the Fe5C2 phase to the Fe3C phase. The results showed that CO conversions and products selectivity were affected by both the iron carbide phases and the surface carbon layer. CO conversion was higher (75–96%) when Fe5C2 was the dominant iron carbide. The selectivity to C5+ products was higher when Fe3C was alone, while the light olefins selectivity was higher when the two components (Fe5C2 and Fe3C phases) co-existed, but the quantity of Fe3C was small.

Synthesis of Rod-Like Porous MgFe2O4 Architectures as a Catalyst for Ammonium Perchlorate Thermal Decomposition

The development of highly active catalysts for the pyrolysis of ammonium perchlorate (AP) is of considerable importance for AP-based composite solid propellant. In the present study, we produced porous MgFe2O4 architectures by using a facile two-step strategy. A rod-like precursor of MgFe2(C2O[Formula: see text]O (diameter: 0.5–2.5[Formula: see text][Formula: see text]m; length: 2–15[Formula: see text][Formula: see text]m) was fabricated under solvothermal conditions using metal sulfates as raw materials and oxalic acid as the precipitant. Subsequently, porous MgFe2O4 architectures were obtained by the thermal treatment of the as-prepared oxalate precursor, during which the mesopores were formed in situ via the liberation of volatile gases, while the rod-like morphology was well preserved. The catalytic performances of the as-synthesized porous rod-like MgFe2O4 architectures with respect to the AP pyrolysis were assessed using differential scanning calorimetry (DSC) techniques. The results indicated that the high thermal decomposition temperature and the apparent activation energy of AP with 2[Formula: see text]wt.% MgFe2O4 addition decreased from 445.4[Formula: see text]C to 386.7[Formula: see text]C and from [Formula: see text] to [Formula: see text][Formula: see text]kJ mol[Formula: see text], respectively. Meanwhile, the decomposition heat of AP with MgFe2O4 as the additive reached up to 1230.6[Formula: see text]J g[Formula: see text], which was considerably higher than that of its neat counterpart (695.8[Formula: see text]J g[Formula: see text]. Thus, porous rod-like MgFe2O4 architectures could be served as the catalyst for the AP pyrolysis.