New Electrochemistry-Based Approaches to Brandy Quality Evaluation Using Antioxidant Parameters

The electrochemical approaches based on coulometric titration, differential pulse voltammetry (DPV), and chronoamperometry have been tested for applicability to evaluation of brandy quality. The antioxidant properties of samples have been considered as markers of adulteration. Total antioxidant capacity (TAC), ferric reducing power (FRP), as well as ellagic acid equivalent antioxidant capacity (EAE AOC) have been evaluated for ten samples five of which have been recognized as adulteration by gas chromatography. Electrochemical data for adulterations and brandies are significantly different. TAC and FRP values for all adulterated samples are approximately the same (10?±?3 and 6?±?2 C/100 mL for TAC and FRP, respectively) while brandies show TAC in the range of 24–108 and FRP of 20–88 C/100 mL depending on denomination and origin. DPV profile of adulterations is strongly different in comparison with brandy (the required peaks are absent and irrelevant peaks are appeared), allowing sample discrimination. Addition of vanillin-containing flavoring agents has been confirmed. The corresponding EAE AOC of brandies is 8–15-fold higher (depending on denomination) than that for adulterations. Two adulterations did not show EAE AOC, reflecting the absence of aging step during beverage production. Chronoamperometric EAE AOC equals to zero for four investigated adulterations. Standard antioxidant parameters antioxidant activity and total phenolic content can be applied for the preliminary screening only. These parameters are ineffective for adulteration of the beverage age using oak extracts. Electrochemical methods developed are characterized by simplicity, cost-efficiency, and reliability of results and can be successfully applied for the brandy quality control.     

Modelling and characterization of piezoelectric and polarization gradients

A gradient of the piezoelectric properties in monolithic ceramics can be useful to minimize mechanical stresses inside piezoelectric bending actuators or at interfaces between layers with different electromechanical properties, and increase the bandwidth of ultrasonic transducers. Piezoelectric gradients can be prepared by different techniques. We use a powder pressing technique to prepare a gradient of the chemical composition, which is transformed to the piezoelectric gradient by the poling process. Conventional mixed-oxide powders of BaTiO₃ with different amount of Sn from 7.5 up to 15 mol% and Mn-doped BaTiO₃ were used to produce lead-free ceramic samples. We describe the poling process using a equivalent circuit approach. The ferroelectric behavior of the different layers are described by the Preisach model. In the Ba(Ti,Sn)O₃ system the properties can be changed from ferroelectric to paraelectric depending on the Sn content. A gradient of polarization and piezoelectric properties can be observed in monolithic ceramics with a tin gradient. The profile of the polarization distribution was measured by the thermal wave method. A gradient of polarization where the sign of polarization changes can be induced in a system consisting of piezoelectric hard and soft materials. We describe a special poling process using our poling model. The principle is demonstrated in a two layer model system.     

Assessment of Metals Pollution from Tailing Sites in the North Caucuses Region,Russia

The concentrations of metals were determined in the water and bottom sediments of both the Urup and Kuban Rivers near tailings sites in the North Caucasus region of southern Russia. The average concentrations in the Urup followed the order Fe?>?Mn?>?Pb?>?Cu?>?Zn?>?Cd?>?Ni?>?Co, while in the Kuban, the order was Fe?>?Pb?>?Zn?>?Ni?>?Mn?>?Cd, with copper and cobalt not detected. The levels of Zn, Cu, Pb, Cd, and Ni were above Russia’s maximum permissible concentration in both rivers. The water pollution index (WPI) values in Urup ranged from 12.97 to 28.17, indicating that the river is extremely polluted (Class VII), while the WPI value for Kuban ranged from 2.34 to 4.33 downstream of the tailings site, which corresponds to Class IV (contaminated). Calculating the coefficient of accumulation in sediments (CAS) revealed that in Urup, the CAS values for Ni and Cu were 3046 and 11638, respectively, which indicates an emergency environmental situation, while for Co, Fe, and Mn, the situation is high level chronic pollution (CAS?>?10⁴). The Kuban CAS values of Fe and Mn were also >?10⁴, again highly and chronically polluted. Most of the metals in both rivers are bound to the sediments, with minimal mobility. The potential ecological risk is moderate to considerable in Urup, and low in the Kuban River.     

Synthesis of yttrium titanate stannate (Y2Ti2−xSnxO7, x = 0–2) pyrochlore glass–ceramics as potential nuclear waste form

Y₂Ti_2−xSn_xO₇ (x = 0–2) pyrochlore sodium aluminoborosilicate glass–ceramics (GCs) are produced by calcining the pelletized Y–Ti–Sn oxide mixture and glass precursor at 1200 or 1300°C for 4 h. The metal oxide mixture is prepared by a soft chemistry route. X-ray diffraction, Raman spectroscopy, and electron microscopy are employed to investigate the formation of pyrochlore GCs and local crystal structures. Near phase pure Ti-rich pyrochlores are produced with minor phase SnO₂ observed for Sn-rich materials. The cell parameters of the pyrochlore structures refined by Le Bail fitting are in good agreement with the published data and increase linearly with the gradual increment of Sn substitution. With progressively increasing Sn proportion on pyrochlore B-site, Raman characteristic bands of the pyrochlore structure become sharper and well defined. The Raman A_1g peak position and its full width at half-maximum are linearly progressed with increasing x (Sn). The presence of the melting glass facilitates the pyrochlore formation, with ceramic grain sizes ranging from submicron to microns. Transmission electron microscopy and selected area electron diffraction observations indicate the sample possesses a relatively high crystallographic perfection at the atomic level. This new series of pyrochlore GCs and the method disclosed herein may pave the way for further materials development as potential nuclear waste forms.