Effects of reaction conditions on laccase‐catalyzed α‐naphthol polymerization

Enzymatic oxidative polymerization of α‐naphthol was carried out batch‐wise with the laccase enzyme, produced by Trametes versicolor (ATCC 200801). The polymerization reaction was conducted in a closed, temperature controlled system containing acetone (solvent) and sodium acetate buffer for pH control. The effects of the organic solvent (acetone) composition, monomer (α‐naphthol) and enzyme concentrations, buffer pH and temperature on the polymerization rate were investigated with respect to initial reaction conditions and depletion rate of dissolved oxygen. The optimum acetone composition, pH, monomer, dissolved oxygen and enzyme concentrations were determined as 50% (v/v), 5, 3409 gm⁻³, 20.3 gm⁻³ and 0.173 U cm⁻³, respectively; these values provided the most desirable conditions for initial reaction rate. Temperature rise supported the rate increase up to 37 °C, after which the rate tended to be stable due to a drop in dissolved oxygen concentration. The product polymer, poly(α‐naphthol), with an average molecular weight of 4920 Da was soluble in common organic solvents. © 2000 Society of Chemical Industry     

Experimental Investigation of the Effect of Fire Protection Lobby on Stair Pressurization System in a High-Rise Building

In this study, the stair pressurization system in a 40-storey high office building in Istanbul is investigated through field tests, in order to understand the effect of the presence of a non-pressurized vestibule (fire protection lobby, FPL) before entering the stair at each floor. The building without FPL is simulated by keeping only one of the two doors (of the stair and FPL) open at each floor. This method gave an opportunity to fix other parameters affecting the stair pressurization system and check solely the effect of FPL. Two different cases are taken into account, where the first one (all doors closed) analyses the condition that all stair doors are kept closed and the second one (critical doors are open) is conducted when the stairwell is opened to the floor on a given level (fire floor) and the stair termination door at the discharge floor is kept open. For both cases, the availability of the FPL is investigated by using the aforementioned arrangement. Under the conditions with approximately the same pressurized air flow rate at all doors closed condition, it is found that the availability of FPL increases the pressure difference between the stairwell and the corridor by a factor of approximately 2.2. This is also justified by using empirical formulations available in literature, where this ratio is calculated as 2.0. The results of this study showed that the FPL arrangement improves the effectiveness of pressurization system in a very high-rise building, despite some tolerable drawbacks.     

Adsorption of trypsin onto magnetic ion‐exchange beads of poly(glycidylmethacrylate‐co‐ethyleneglycoldimethacrylate)

Magnetic beads were prepared from glycidyl methacrylate (GMA), and ethyleneglycol dimethylmethacrylate (EGDMA) in the presence of Fe₃O₄ nano‐powder via suspension polymerization. The magnetic beads were characterized by surface area measurement, electron spin resonance (ESR), and scanning electron microscopy (SEM). ESR data revealed that the beads were highly super‐paramagnetic. The effects of contact time, pH, ionic strength, and temperature on the adsorption process have been studied. Adsorption equilibrium was established in about 120 min. The maximum adsorption of trypsin on the magnetic beads was obtained as 84.96 mg g^?1 at around pH 7.0. At increased ionic strength, the contribution of the electrostatic component to the overall binding decreased, and so the adsorption capacity. The experimental equilibrium data obtained trypsin adsorption onto magnetic beads fitted well to the Langmuir isotherm model. The result of kinetic analyzed for trypsin adsorption onto magnetic ion‐exchange beads showed that the second order rate equation was favorable. It was observed that after six adsorption–elution cycle, magnetic beads can be used without significant loss in trypsin adsorption capacity. Finally, the magnetic beads were used for separation of bovine serum albumin (BSA) and trypsin from binary solution in a batch system. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

High-Performance Liquid Chromatography Analysis and Assessment of Benzoic Acid in Yogurt, Ayran, and Cheese in Turkey

Among food sources, particular attention is paid to milk and dairy products, due to its nutritional importance. Benzoic acid is extensively used in the preservation of foods. A reliable method for the determination of benzoic acid in some dairy products, such as yogurt, ayran, and cheese using high-performance liquid chromatography and UV detection was validated. The peak of benzoic acid was measured at a wavelenght of 226 nm. Samples were purchased from supermarkets in Turkey in the period 2009–2010. All dairy product samples were produced from cow’s milk. The levels of benzoic acid in cheese, yogurt, and ayran samples were in the range of 3.17 to 56.77 mg kg⁻¹, 8.94 to 28.30 mg kg⁻¹, and 1.54 to 16.57 mg L⁻¹, respectively. The results show that benzoic acid widely occurs in milk products in Turkey at the low levels.     

Utilization of Waste Yarns in Hair Interlining Industry

There has been an innovation need for utilizing fine yarn wastes nowadays. In this study, probability of using yarn wastes in hair interlining industry has been investigated. Information about hair interlining was given and production problems were investigated. It was underlined that by using wastes these problems can be solved environment-consciously. Mass per unit area, breaking strength, elongation at break, fiber blending ratio, circular bending stiffness, and dimensional change of standard and environment-friendly interlinings were tested and comparatively investigated. Consequentially, environment-friendly hair interlinings produced from different yarn wastes have lower shrinkage results. It was found that breaking strength, elongation at break, and circular bending stiffness results of the two fabrics had no remarkable difference. With this study, suitable utilizing area for waste yarns were found and singeing and sizing steps of the production were eliminated. In every sense, this study brings innovations for hair interlining production and makes contributions to the environment.     

Carotid-jugular arteriovenous fistula and cerebrovascular infarct: a case report of an iatrogenic complication following internal jugular vein catheterization

Central venous catheterization is frequently performed for perioperative management and long-term intravenous access. Although complications associated with central venous catheter insertion have been widely reported, there are few reports of carotid-jugular arteriovenous fistula formation. Endovascular procedures are associated with a risk of immediate and delayed thromboembolic and ischemic complications. We describe a case of a carotid-jugular arteriovenous fistula and a cerebrovascular infarct following the insertion of a double-lumen catheter for hemodialysis access. We provide recommendations for the prevention and the early detection of this iatrogenic complication.     

Determination of optimum operating conditions and simulation of drying in a textile drying process

In this study, drying behavior of viscose yarn bobbins was investigated experimentally to specify the optimum drying conditions and a drying model was proposed for simulation of drying. The experiments were conducted in a pressurized hot-air bobbin dryer, which was designed and manufactured based on the dryers used in the textile industry. Drying process was performed for various drying parameters: bobbin diameter, drying temperature, drying pressure, and volumetric flow rate of drying air. The results show that total drying time is strongly dependent on drying pressure, drying temperature, and volumetric flow rate and increase at these parameters shortens the drying time considerably. The results also show that the minimum energy consumption is for lower values of drying temperature and drying pressure and modest and higher values of volumetric flow rate. Simulation results show that the most appropriate model in describing the drying curves of viscose yarn bobbins is the stretched exponential model.     

Assessment of the antioxidant potential and fatty acid composition of four Centaurea L. taxa from Turkey

This paper focused on the assessment of antioxidant property and fatty acid composition of four Centaurea species. The antioxidant activity of its methanol extract was evaluated by several in vitro experiments including phosphomolybedum assay, DPPH assay, β-carotene/linoleic acid, ferric and cupric reducing power. Total phenolic and flavonoid contents were also evaluated. The methanol extract of Centaurea pulcherrima var. pulcherrima showed the superior free radical scavenging activity, linoleic acid inhibition capacity, reducing power and also had the highest total phenolic content. A significant relationship between antioxidant capacity and total phenolic components was found. The oils of Centaurea taxa were also analysed for fatty acid concentration by gas chromatography. The principal fatty acids in the species were palmitic acid (23.38–30.49%) and linoleic acid (20.19–29.93%). These findings suggest that the Centaurea species could be used as a potential source of new natural antioxidants and unsaturated fatty acids in food industry, cosmetics and pharmaceutical preparations.     

Screening of Possible In Vitro Neuroprotective,Skin Care,Antihyperglycemic, and Antioxidative Effects of Anchusa undulata L. subsp. hybrida (Ten.) Coutinho from Turkey and Its Fatty Acid Profile

The aim of this work was to determine antioxidant capacities, neuroprotective, skin care, antidiabetic effects, and fatty acid composition of Anchusa undulata subsp. hybrida. The antioxidant activity was screened by four different test systems including total antioxidant, antiradical, reducing power, and metal chelating activities. Neuroprotective potential was determined by anticholinesterase inhibitor assay. Tyrosinase inhibitory activity was tested to detect skin care effect. Antidiabetic effects were evaluated with α-amylase and α-glucosidase inhibitory assays. Inhibitory activities on acetycholinesterase, butyrylcholinesterase, tyrosinase, α-amylase, and α-glucosidase enzymes were observed as 2.238 and 1.239 μmol GALAEs/g, 0.339 mmol KAEs/g, 0.193, and 0.219 mmol ACEs/g extract, respectively. Amount of total phenolics and flavonoids were found as 80.34 μg GAEs/mg and 25.09 μg QEs/mg in the extract, respectively. Twenty-three fatty acids were found in the aerial parts, being oleic acid (24.30 g/100 g of total fatty acids) the most abundant, followed by linoleic (21.19 g/100 g of total fatty acids) and palmitic acids (17.50 g/100 g of total fatty acids).