Polyol Synthesis and Investigation of Ce1−xRExO2−x/2 (RE = Sm,Gd, Nd,La, 0 ≤ x ≤ 0.25) Electrolytes for IT‐SOFCs

In this study, we aimed to examine the effect of dopant type and concentration on the ionic conductivity of ceria‐based electrolytes. Ceria electrolytes doped with samarium (SDC), gadolinium (GDC), neodymium (NDC), and lanthanum (LDC) for solid oxide fuel cells were prepared through the polyol process. Acetate compounds of cerium and dopants were used as starting materials, and triethylene glycol was used as a solvent. Prepared powders and pellets were characterized by TG/DTA, XRD, FTIR, SEM, EIS, and EDS techniques. The results of the TG/DTA and XRD indicated that a single‐phase fluorite structure formed at the relatively low calcination temperature of 500°C. The relative densities of the pellets were higher than 90% and these finding were supported by the SEM images. The lattice parameters of the samples increased with the dopant concentration. According to the electrochemical analysis results, the samples with maximum conductivity values were SDC‐20, GDC‐15, NDC‐15, and LDC‐15. The results of the impedance spectroscopy revealed that the SDC‐20 sample exhibited the highest ionic conductivity with a value of 4.29 × 10^?2 S/cm at 800°C in air.     

Thermal conductivity of MgO-C refractory ceramics: Effects of pyrolytic liquid and pyrolytic carbon black obtained from waste tire

In the present study, thermal conductivity and mechanical properties of MgO-C refractory ceramic bricks were investigated. Pyrolytic liquid and pyrolytic carbon black obtained from pyrolysis of waste tires were used as a resin and carbon source, respectively. The pyrolysis of the tires was conducted in a fixed bed reactor at the temperature of 500?°C with a 15?°C/min heating rate under nitrogen flow (0.5?lt/min). Before using in MgO-C refractory ceramic blends, pyrolytic products were purified with the acidic extraction methods which resulted in 61and 66?wt%. decreases in sulfur and ash contents in pyrolytic carbon, respectively. After this treatment of pyrolytic liquid, the sulfur content was reduced by 24?wt%. Eight different blends of MgO-C refractory ceramics consisting of different pyrolytic product contents were prepared, pressed, and tempered at 250?°C, and then characterized in terms of porosity, thermal conductivity, and density. The mechanical behavior of the samples was tested using a three-point bending test. Archimedes test was employed to determine the porosity and density. Surface properties of the bricks were analyzed by scanning electron microscopy (SEM). The obtained results were compared with a reference consisting of graphite and resin. The results revealed that mechanical and thermal properties of the developed bricks were highly sensitive to the porosity and the carbon source as well as the type of binder.     

Free Radical Scavenging and Cellular Antioxidant Properties of Astaxanthin

Astaxanthin is a coloring agent which is used as a feed additive in aquaculture nutrition. Recently, potential health benefits of astaxanthin have been discussed which may be partly related to its free radical scavenging and antioxidant properties. Our electron spin resonance (ESR) and spin trapping data suggest that synthetic astaxanthin is a potent free radical scavenger in terms of diphenylpicryl-hydrazyl (DPPH) and galvinoxyl free radicals. Furthermore, astaxanthin dose-dependently quenched singlet oxygen as determined by photon counting. In addition to free radical scavenging and singlet oxygen quenching properties, astaxanthin induced the antioxidant enzyme paroxoanase-1, enhanced glutathione concentrations and prevented lipid peroxidation in cultured hepatocytes. Present results suggest that, beyond its coloring properties, synthetic astaxanthin exhibits free radical scavenging, singlet oxygen quenching, and antioxidant activities which could probably positively affect animal and human health.     

Atmospheric deposition of polycyclic aromatic hydrocarbons (PAHs) in mosses (Hypnum cupressiforme) in Hungary

The atmospheric deposition of polycyclic aromatic hydrocarbons (PAHs) was investigated in Hungary by analyzing a moss (Hypnum cupressiforme) species as a bioindicator. In the autumn of 1997, samples were collected at 29 sites distributed across Hungary. The concentrations of total PAH at these sites were in the range of 0.1567-10.45 x 10(4) microg kg(-1) with a mean value of 1.87 x 10(4) microg kg(-1). More than 99% of the total PAHs atmospheric deposition were low molecular weight PAHs (up to 3 ring compounds). The total PAH values showed no correlation with metal concentrations. However, most of the sites in this region showed a positive linear relationship between PAHs levels and traffic volume (r2 = 0.83; P < 0.001) while no relationship existed between PAH levels and population (r2 = 0.01; P > 0.1). Atmospheric deposition of PAHs at different regions in Hungary may be due to incomplete combustion of fuel. The total concentrations of PAHs were compared to the PAH levels in vegetation samples collected from different regions around the world. The highest PAHs concentrations accumulated were found in Hypnum cupressiforme than other vegetation species. A greater affinity for PAH compounds by Hypnum cupressiforme than other moss species probably caused larger amounts of accumulation. A relationship between accumulations of PAH compounds in Hypnum cupressiforme and octanol-air partition coefficients was obtained and is briefly discussed.     

Continuous fermentative hydrogen production from cheese whey wastewater under thermophilic anaerobic conditions

Hydrogen (H₂) production from cheese processing wastewater via dark anaerobic fermentation was conducted using mixed microbial communities under thermophilic conditions. The effects of varying hydraulic retention time (HRT: 1, 2 and 3.5 days) and especially high organic load rates (OLR: 21, 35 and 47 g chemical oxygen demand (COD)/l/day) on biohydrogen production in a continuous stirred tank reactor were investigated. The biogas contained 5–82% (45% on average) hydrogen and the hydrogen production rate ranged from 0.3 to 7.9 l H₂/l/day (2.5 l/l/day on average). H₂ yields of 22, 15 and 5 mmol/g COD (at a constant influent COD of 40 g/l) were achieved at HRT values of 3.5, 2, and 1 days, respectively. On the other hand, H₂ yields were monitored to be 3, 9 and 6 mmol/g COD, for OLR values of 47, 35 and 21 g COD/l/day, when HRT was kept constant at 1 day. The total measurable volatile fatty acid concentration in the effluent (as a function of influent COD) ranged between 118 and 27,012 mg/l, which was mainly composed of acetic acid, iso-butyric acid, butyric acid, propionic acid, formate and lactate. Ethanol and acetone production was also monitored from time to time.To characterize the microbial community in the bioreactor at different HRTs, DNA in mixed liquor samples was extracted immediately for PCR amplification of 16S RNA gene using eubacterial primers corresponding to 8F and 518R. The PCR product was cloned and subjected to DNA sequencing. The sequencing results were analyzed by using MegaBlast available on NCBI website which showed 99% identity to uncultured Thermoanaerobacteriaceae bacterium.     

Study and determination of the herbicide cyclosulfamuron by square wave stripping voltammetry

The voltammeric behavior of the herbicide cyclosulfamuron has been studied by square wave stripping voltammetry (SWSV). Cyclosulfamuron was reduced on a static mercury drop electrode (SMDE) and gave a well-defined peak in the pH range of 3.0-7.0. The peak potential (E_p) shifts to a more negative potential with increasing pH. The ratio ΔE_p/ΔpH over the pH range studied was 59.5 mV/pH. A systematic study of the various experimental parameters that affect the stripping response was studied by SWV. The square wave parameters used were a frequency of 150 Hz, an amplitude of −60 mV and a staircase step of 6.0 mV. The quantifications were performed by the standard addition method, from the SW voltammetric peak obtained at −1348 mV. Calibration curves were linear in the range of 10-350 μg L⁻¹ with a detection limit of 3.5 μg L⁻¹ under the conditions used (pH 6.0 buffer solution, E_acc = −400 mV vs. Ag/AgCl, t_acc = 75 s). The validity of the developed methodology was assessed by recovery experiments at the 25-100 μg L⁻¹ level. The mean results for 3 determinations were 49.7 ± 3.3 μg L⁻¹, which is very close to the amount of cyclosulfamuron added to soil (50 μg L⁻¹), with a recovery of 99.4%. The sufficiently good recoveries and low relative standard deviation (RSD) data reflects the high accuracy and precision of the proposed SW voltammetric method. The possible influences of various inorganic species and other pesticides were also investigated.     

The effects of using transglutaminase,exopolysaccharide‐producing starter culture and milk powder on the physicochemical,sensory and texture properties of low‐fat set yoghurt

This study focused on the effects of transglutaminase (TGase), exopolysaccharide (EPS)‐producing starter culture or skim milk powder addition on some properties of low‐fat set yoghurt. The incorporation of TGase to yoghurt did not affect the acidity of the experimental samples. However, the proteolytic activity of the starter culture significantly decreased in TGase‐treated yoghurt. Addition of TGase to yoghurt with a low dry matter content (11.08%) resulted in low serum separation and gel firmness and viscosity close to those of yoghurt with a higher dry matter content (14.81%). According to the sensory results, it would be possible to produce an acceptable product with a low dry matter and low fat content using TGase. The results shown that the use of EPS‐producing starter cultures for the purpose of improving the texture properties of low dry matter content yoghurt could not be recommended.