Detection of gamma irradiated fig seeds by analysing electron spin resonance

Seeds of fig produced in Turkey were studied by electron spin resonance (ESR) technique for detection purposes. Unirradiated fig seeds (control) exhibited a weak ESR singlet at g = 2.0052 ± 0.0003 (native signal). Irradiation induced at least one additional intense singlet overlapping to the control signal and caused a significant increase in signal intensity without any changes in spectral patterns. Variation of ESR signal intensity of irradiated samples at room temperature with time in a long-term showed that free radicals responsible from the ESR spectrum of fig seeds were not stable but detectable after 80 days. Annealing studies at five different temperatures were used to determine the kinetic behaviour and activation energy of the radiation-induced radicals in fig seeds. A study on microwave saturation characteristics and thermal behaviour of the ESR singlet (g = 2.0052) in irradiated and unirradiated fig seed samples was also carried out by using ESR technique. These preliminary results indicate that microwave saturation characteristics of the ESR signal at room and low temperatures may be useful method to distinguish irradiated fig seeds from unirradiated ones.     

A critical review on progress of the electrode materials of vanadium redox flow battery

Nowadays, renewable energy sources are taken great attention by the researchers and the investors around the world due to increasing energy demand of today's knowledge societies. Since these sources are non-continuous, the effective storage and re-use of the energy produced from renewable energy sources have great importance. Although classical energy storage systems such as lead acid batteries and Li-ion batteries can be used for this goal, the new generation energy storage system is needed for large-scale energy storage applications. In this point, vanadium redox flow batteries (VRFBs) are shinning like a star for this area. VRFBs consist of electrode, electrolyte, and membrane component. The battery electrodes as positive and negative electrodes play a key role on the performance and cyclic life of the system. In this work, electrode materials used as positive electrode, negative electrode, and both of electrodes in the latest literature were complained and presented. From graphene-coated and heteroatom-doped carbon-based electrodes to metal oxides decorated carbon-based electrodes, a large scale on the modification of carbon-based electrodes is available on the electrode materials of the VRFBs. By the discovering of novel electrode components for the battery system, the using of the VRFBs probably increase in a short time for many industrial and residential applications.     

Thermal Fatigue Testing of Plasma Transfer Arc Stellite Coatings on Hot Work Tool Steels under Steel Thixoforming Conditions

The thermal fatigue performance of Stellite 12 coating deposited on X32CrMoV33 hot work tool steel via the plasma transfer arc (PTA) process was investigated under steel thixoforming conditions. Stellite 12 coating has made a favorable impact on the thermal fatigue performance of the X32CrMoV33 hot work tool steel. The latter survived steel thixoforming conditions lasting much longer, for a total of 5000 cycles, when coated with a PTA Stellite 12 layer. This marked improvement is attributed to the higher resistance to oxidation and to temper softening of the Stellite 12 alloy. The Cr-rich oxides, which form during thermal cycling, provide adequate protection to high-temperature oxidation. In contrast to hot work tool steel, Stellite 12 alloy enjoys hardening upon thermal exposure under steel thixoforming conditions. This increase in the strength of the coating is produced by the formation of carbides and contributes to the superior thermal fatigue resistance of the Stellite 12 alloy. When the crack finally initiates, it propagates via the fracture of hard interdendritic carbides. The transformation of M₇C₃ to M₂₃C₆, which is more voluminous than M₇C₃, promotes crack propagation.     

Investigation of photocatalytic properties of TiO2 nanoparticle coating on fly ash and red mud based porous ceramic substrate

Titanium dioxide is one of the best semiconducting photocatalysts available for photocatalytic cleaning applications. Especially nano-sized TiO₂ particles deposited on porous substrates can be utilized as a filter for solid and liquid media. On the other hand, red mud and thermal plant fly ash are hazardous wastes that are produced in large quantities. Recycling/reuse of these waste material in a porous ceramic production would be beneficial both for environmental and economical issues. In the present study, a porous substrate was produced from red mud and fly ash with varying ratios and additives of H₃BO₃, CaCO₃, and MgCO₃ for lowering the melting temperature and porosity formation. Sintered ceramics were then coated with nano-sized TiO₂ particles by the sol-gel method. Ultrasonic dispersion of nano-sized TiO₂ nanoparticles was also utilized as an alternative method for impregnation of nanoparticles into the porous structure of the ceramic substrate. Finally, photocatalytic activities and degradation of methylene blue (MB) under UV radiation of substrates were investigated. According to the SEM investigations, the sol-gel method was observed to be a better way of nanoparticle deposition because deposited particles are homogenous throughout the ceramic body. Also, this method provides lower particle sizes than the ones that were deposited by the ultrasonic dispersion method. This results in higher surface area and better photocatalytic activities.     

Effect of iron and molybdenum addition on photofermentative hydrogen production from olive mill wastewater

Photofermentative hydrogen production from olive mill wastewater (OMW) by Rhodobacter sphaeroides O.U.001 was assessed under iron and molybdenum supplementation. Control cultures were only grown with 2% OMW containing media. The analysis included measurements of biomass accumulation, hydrogen production, pH variations of the medium, and changes in the chemical oxygen demand (COD) of the wastewater. Growth under control and Mo-supplemented experiments yielded about the same amount of biomass (∼0.4 g dry cell weight per L culture). On the other hand, Mo addition slightly enhanced the total volume of H₂ gas production (62 mL H₂), in comparison with the control reactor (40 mL H₂). Fe-supplemented cultures showed a significant increase on H₂ production (125 mL H₂), tough having a longer lag time for the observation of the first H₂ bubbles (24 h), compared to the control (15 h) and Mo-supplemented ones (15 h). Fe-added cultures also yielded better wastewater treatment by achieving 48.1% degradation of the initial chemical oxygen demand (COD) value compared to the control reactor having 30.2% COD removal efficiency. Advances described in this work have the potential to find applications in hydrogen industry while attempting an effective management of cheap feedstock utilization.     

Effect of microbial transglutaminase, sodium caseinate and non-fat dry milk on quality of salt-free, low fat turkey döner kebab

Effects of microbial transglutaminase (MTGase) and its combinations with sodium caseinate (SC) or non-fat dry milk (NFDM) on quality of salt-free, low fat turkey döner kebab were investigated. The purpose of this study was to prevent quality deteriorations (e.g. cooking loss, textural problems) caused by a lack of salt in the product. The results of this study indicated that the use of MTGase can minimize textural quality loss caused by a lack of salt in turkey döner manufacture (p < 0.05). When the enzyme was combined with SC, or NFDM, its effect on texture was enhanced (p < 0.05) and improved cooking yield, moisture and sensory properties compared to the corresponding control manufactured without the enzyme, salt, SC and NFDM. (p < 0.05), however, there was no significant effect on pH and color As a result, the possible quality problems which may occur in salt free, low fat turkey döner can be overcome by the use of combinations of MTGase with SC or NFDM.     

Biological hydrogen production from sugar beet molasses by agar immobilized R. capsulatus in a panel photobioreactor

Biohydrogen production from sugar beet molasses was investigated by using agar immobilized R. capsulatus YO3. A panel photobioreactor (1.4 L) was employed for a long-term hydrogen production in both indoor and outdoor conditions. The impact of several initial molasses concentrations on hydrogen production, yield and productivity were assessed. Indoor studies revealed that initial sucrose concentration in molasses should be kept below 20 mM to prevent inhibition of hydrogen production. The highest hydrogen productivity of 0.64 ± 0.06 mmol H₂ L^?1 h^?1 and yield of 12.2 ± 1.5 mol H₂/mol sucrose were obtained in indoors throughout 20 days of operation. For outdoors, hydrogen production continued for 40 days including consecutive 10 rounds under natural outdoor conditions. In outdoor conditions, the maximum hydrogen productivity and yield were 0.79 ± 0.04 mmol H₂ L^?1 h^?1 and 5.2 ± 0.4 mol H₂/mol sucrose respectively. These results indicate that the proposed system is promising for biohydrogen production from molasses at large-scale natural conditions.     

Effect of surface treatments and aging on phase transformation and flexural strength of different Y-TZP ceramics

This study aimed to evaluate the influence of surface treatments and artificial aging on surface roughness (Ra), phase transformation, and flexural strength of yttria-stabilized tetragonal zirconia polycrystalline (Y-TZP) ceramics. Two-hundred and eighty specimens from four types of Y-TZP were divided into seven groups, according to the surface treatments and aging used: control, air-abrasion, air-abrasion + aging, grinding, grinding + aging, erbium: yttrium-aluminum-garnet (Er:YAG) laser, Er:YAG laser + aging. The Ra values were measured using a profilometer. X-ray diffraction (XRD) analysis was performed to determine phase transformation. Specimens were subjected to a three-point bending test and loaded until fracture. Scanning electron microscope (SEM) and atomic force microscope (AFM) analyses were performed on one specimen per group. Grinding and air-abrasion groups exhibited higher Ra values than the others (P < 0.05). The differences in the roughness and flexural strength values between the laser and control groups were not significant. For all materials, the highest amount of monoclinic phase was found after air-abrasion. Grinding groups showed lower flexural strength values compared with the control groups (P < 0.05), while there was no significant difference between the control and air-abrasion groups. Aging did not affect the roughness and flexural strength (P > 0.05). The grinding process is not recommended in clinical usage for Y-TZP because of the remarkable decrease in flexural strength and reliability.     

In vitro antimicrobial activity of essential oil from endemic Origanum minutiflorum on ciprofloxacin-resistant Campylobacter spp.

This study evaluated the antimicrobial activities of an essential oil of Origanum minutiflorum (O. Schwarz and P.H. Davis) against ciprofloxacin-resistant Campylobacter spp., by broth microdilution and agar well-diffusion methods. Moreover, O. minutiflorum oil was analyzed by gas chromatography/mass spectrometry (GC/MS). Twenty-nine components were identified, representing 98.7 of the oil. The oil yield from the plants was 4.0–4.4% v/w. The major components of O. minutiflorum oil were carvacrol (73.9%) and p-cymene (7.20%). The oil has lower contents of carvacrol methyl ether (0.05%), heptadecanol (0.06%) and carvacryl acetate (0.06%). Twenty-one Campylobacter spp. (12 C. jejuni, 5 C. lari and 4 C. coli) strains using in this study were selected among 300 isolates according to their resistance to ciprofloxacin. The minimum inhibitory concentration (MIC) values for bacterial strains, which were sensitive to the essential oil of O. minutiflorum, were in the range of 7.8–800 μg/ml. The essential oil obtained showed strong antimicrobial activity against all of the tested ciprofloxacin-resistance Campylobacter spp. These results suggest that the essential of O. minutiflorum may be used as a natural preservative in food against food-born disease, such as Campylobacteriosis.     

Kinetics of adsorption in bi-porous molecular sieves. Part II: Comparison of theory and experiment for batch systems

Experimental kinetic uptake curves for two sorbates (cis-2-butene from the gas phase and n-heptane from the liquid phase) have been measured in a variety of 5A molecular sieve pellets. Conditions were selected to fulfil either the linear isotherm approximation of the Ruckenstein⁽³⁾ model or the rectangular isotherm approximation of the preceding paper. For these systems both macropore and micropore diffusional resistances are significant and it is shown that the theoretical models provide a satisfactory interpretation of the experimental uptake curves. Time constants for both macropore and micropore diffusion, calculated by matching experimental and theoretical uptake curves, are consistent with independently measured values.