Effect of ozonation on chemical oxygen demand fractionation and color profile of textile wastewaters

Filtration and ultrafiltration with a size range of 2–1600 nm were used to evaluate the effect of ozonation on the particle size distribution‐based chemical oxygen demand (COD) and color profiles of textile wastewater before and after biological treatment. Ozonation induced a net effect of 9% COD reduction in the influent and 15% in the effluent. However, a more in‐depth evaluation based on particle size distribution and mass balance for the influent revealed different mechanisms of ozonation, which were interpreted as total oxidation in the soluble range, replenishment of soluble COD through solubilization of organics into simpler compounds and polymerization towards the upper size range (>220 nm). For the biological treatment effluent, the greatest effect of ozonation was in the lower particle size range (<8 nm). Ozone was very effective for color removal, giving 80–93% optical density reductions in the influent and 96–99% in the effluent, depending on the excitation wavelength selected. Ozonation of the influent removed practically all color fractions, except in the particulate range. In the effluent, the particulate fraction was removed by biological treatment and settling and consequently the remaining color were almost entirely removed by ozonation. Copyright © 2005 Society of Chemical Industry     

The effect of 1.5 T and 3 T magnetic resonance imaging on microleakage of amalgam restorations

The aim of this article is to compare the effects of 1.5 T and 3 T MRI on microleakage of amalgam restorations. A total of 90 extracted molar teeth were used in this study. Amalgam was used to restore standard Class V preparations (5 × 3 × 2 mm). Following the restoration, the teeth were divided into three groups according to magnetic resonance imaging (MRI) protocol (Group I: Control, Group II: 1.5 T MRI, and Group III: 3 T MRI). A total of 6,000 thermal cycles at 5°C–55°C were applied on all samples. Microleakage values were measured in millimeters using the ImageJ program. Microleakage values were higher in the gingival region compared to the occlusal region in all groups and the differences were statistically significant (p < .05). Microleakage values were not statistically different among the groups in the occlusal region (p > .05), while there were statistically significant differences among the groups with respect to microleakage values in the gingival region (p < .01). The highest mean microleakage amount in the gingival region was measured in Group III (1.192 ± 0.941 mm). This was followed by Group II (0.519 ± 0.813 mm) and Group I (0.347 ± 0.726 mm), respectively. Within the limitations of this in vitro study, we observed that higher microleakage values in amalgam restored teeth in which were exposed to MRI procedure. We also found that the teeth exposed to the stronger magnetic field showed higher microleakage amount.     

Photofermentative hydrogen production using dark fermentation effluent of sugar beet thick juice in outdoor conditions

In the present study, photofermentative hydrogen production on thermophilic dark fermentation effluent (DFE) of sugar beet thick juice was investigated in a solar fed-batch panel photobioreactor (PBR) using Rhodobacter capsulatus YO3 (hup⁻) during summer 2009 in Ankara, Turkey. The DFE was obtained by continuous dark fermentation of sugar beet thick juice by extreme thermophile Caldicellulosiruptor saccharolyticus and it contains acetate (125 mM) and NH₄⁺ (7.7 mM) as the main carbon and nitrogen sources, respectively. The photofermentation process was done in a 4 L plexiglas panel PBR which was daily fed at a rate of 10% of the PBR volume. The DFE was diluted 3 times to adjust the acetate concentration to approximately 40 mM and supplemented with potassium phosphate buffer, Fe and Mo. In order to control the temperature, cooling was provided by recirculating chilled water through a tubing inside the reactor. Hydrogen productivity of 1.12 mmol/L_c/h and molar yield of 77% of theoretical maximum over consumed substrate were attained over 15 days of operation. The results indicated that Rb. capsulatus YO3 could effectively utilize the DFE of sugar beet thick juice for growth and hydrogen production, therefore facilitating the integration of the dark and photo-fermentation processes for sustainable biohydrogen production.     

Enhancement of hydrogen storage capacity of multi-walled carbon nanotubes with palladium doping prepared through supercritical CO2 deposition method

Pd doped Multi-Walled Carbon Nanotubes were prepared via supercritical carbon dioxide deposition method in order to enhance the hydrogen uptake capacity of carbon nanotubes at ambient conditions. A new bipyridyl precursor that enables reduction at moderate conditions was used during preparation of the sample. Both XRD analyses and TEM images confirmed that average Pd nanoparticle size distribution was around 10 nm. Hydrogen adsorption and desorption experiments at room temperature with very low pressures (0–0.133 bar) were conducted together with temperature programmed desorption (TPD) and reduction (TPR) experiments on undoped and doped materials to understand the complete hydrogen uptake profile of the materials. TPD experiments showed that Pd nanoparticles increased the hydrogen desorption activity at moderate temperatures around at 38 °C while for undoped materials it was determined around at 600 °C. Moreover, a drastic enhancement of hydrogen storage was recorded from 44 μmol/g sample for undoped material to 737 μmol/g sample for doped material through adsorption/desorption isotherms at room temperature. This enhancement, also verified by TPR, was attributed to spillover effect.     

Screening of the most consumed beverages and spices for their bioactive non-nutrient contents

The present research emphasizes on the bioactive non-nutrient components of the frequently consumed food products daily. The most popular beverages (instant, filter and Turkish coffee, green, black, sage, apple, rosehip, linden and fennel tea infusions) and herbal spices (cinnamon thyme, cumin, mint, sweet pepper, chili pepper, sumac, black pepper and clove) were investigated to evaluate the antioxidant capacities of the samples. Amount of total biophenols (TB) and total flavonoids (TF) were measured by Folin–Ciocalteu and Aluminum chloride colorimetric methods, respectively. CUPRAC (The cupric ion reducing antioxidant capacity) assay and DPPH (α, α-diphenyl-β-picrylhydrazyl) free radical scavenging method were applied to determine the antioxidant activity (AA) of the products. Antimicrobial analyses of the samples were also conducted based on in vitro study. Furthermore, the main biophenol of each sample was identified through high performance liquid chromatography (HPLC). The outcome of the present study will be a useful guidance for the researchers looking for the health benefits of these daily consumed food products.     

Prevalence of β‐Lactamase Producing Escherichia coli from Retail Meat in Turkey

Extended spectrum β‐lactamase (ESBL) and plasmid‐mediated AmpC β‐lactamase (pAmpC) producing Escherichia coli have been shown to be present in humans and animals representing a significant problem worldwide. This study aimed to search the presence of ESBL and/or AmpC‐producing E. coli in retail meats (chicken and beef) in Turkey. A total of 88 β‐lactamase‐producing E. coli were isolated from chicken (n = 81/100) and beef meat (n = 7/100) samples and their susceptibility to several antimicrobials were tested using disc diffusion method. E. coli isolates were further characterized for their phylogenetic groups. β‐Lactamase encoding (bla_TEM, bla_SHV, bla_OXA, bla_CTX‐M, and bla_AmpC) and quinolone resistance genes (qnrA, qnrB, qnrS, qepA, and acc(6′)‐Ib‐cr) were also secreened by polymerase chain reaction (PCR). However, in regard to β‐lactamase genes, 84 of 88 isolates were positive for bla_CTX‐M‐1 (n = 39), bla_CTX‐M‐3 (n = 5), bla_CTX‐M‐15 (n = 4), bla_TEM‐1b (n = 2), bla_SHV‐12 (n = 1), bla_CTX‐M‐1/bla_TEM‐1b (n = 10), bla_CTX‐M‐1/bla_TEM‐1b/bla_SHV‐5 (n = 1), bla_CTX‐M‐1/bla_CMY‐2 (n = 1) and bla_TEM‐1b/bla_CMY‐2 (n = 6), bla_CTX‐M‐15/bla_SHV‐12 (n = 1), bla_CTX‐M‐15/bla_TEM‐1b (n = 1), bla_TEM‐1b/bla_SHV‐12 (n = 1)_, and bla_CMY‐2 (n = 12) genes. Resistance to cefuroxime (75.6% and 85.7%), nalidixic acid (89% and 85.7%), tetracycline (91.4% and 100%), streptomycin (40.2% and 100%), and trimethoprim‐sulfamethoxazole (36.6% and 85.7%) was observed among strains isolated from chicken and beef, respectively. However, all isolates were found to be susceptible to amikacin, imipenem, and cefepime. Resistance to ampicillin and cefoxitin was significantly linked to bla_CMY‐2 gene, while there was a significant correlation between CTX‐M type ESBL and antimicrobial resistance to cefuroxime and streptomycin (P < 0.05). The results of this study suggest that raw chicken retail meats are highly contaminated with ESBL‐producing E. coli implementing a great risk to human health in Turkey.     

Biohydrogen production from beet molasses by sequential dark and photofermentation

Biological hydrogen production using renewable resources is a promising possibility to generate hydrogen in a sustainable way. In this study, a sequential dark and photofermentation has been employed for biohydrogen production using sugar beet molasses as a feedstock. An extreme thermophile Caldicellulosiruptor saccharolyticus was used for the dark fermentation, and several photosynthetic bacteria (Rhodobacter capsulatus wild type, R. capsulatus hup⁻ mutant, and Rhodopseudomonas palustris) were used for the photofermentation. C. saccharolyticus was grown in a pH-controlled bioreactor, in batch mode, on molasses with an initial sucrose concentration of 15 g/L. The influence of additions of NH₄⁺ and yeast extract on sucrose consumption and hydrogen production was determined. The highest hydrogen yield (4.2 mol of H₂/mol sucrose) and maximum volumetric productivity (7.1 mmol H₂/L_c.h) were obtained in the absence of NH₄⁺. The effluent of the dark fermentation containing no NH₄⁺ was fed to a photobioreactor, and hydrogen production was monitored under continuous illumination, in batch mode. Productivity and yield were improved by dilution of the dark fermentor effluent (DFE) and the additions of buffer, iron-citrate and sodium molybdate. The highest hydrogen yield (58% of the theoretical hydrogen yield of the consumed organic acids) and productivity (1.37 mmol H₂/L_c.h) were attained using the hup⁻ mutant of R. capsulatus. The overall hydrogen yield from sucrose increased from the maximum of 4.2 mol H₂/mol sucrose in dark fermentation to 13.7 mol H₂/mol sucrose (corresponding to 57% of the theoretical yield of 24 mol of H₂/mole of sucrose) by sequential dark and photofermentation.