Polycondensation using alkyl chlorosilanes/silicon tetrachloride: Preparation of poly(1,4-benzamide)

Mixtures of alkyl chlorosilane and silicon tetrachloride were used as condensation agents for the preparation of poly(1,4-benzamide). Both high yield of polyamide and soluble side products were obtained. This method may be used to regulate the surface structure and the particle size of silicon dioxide side product if a minimum amount of trimethyl chlorosilane was added to silicon tetrachloride catalyst.     

Hydrothermal Synthesis of Xenotime-Type Gadolinium Orthophosphate

Xenotime-type GdPO₄ (tetragonal, I 4₁/ amd ) has been synthesized hydrothermally at 400°C. X-ray powder data have been presented, and the lattice parameters have been calculated as a = 0.6969(2) nm and c = 0.6095(3) nm.     

Analytical solution to the bending of a nonlinearly hardening wide curved bar

An analytical solution to the partially plastic deformation of a nonlinearly hardening wide curved bar is derived. The bar considered has a narrow rectangular cross-section and is under pure bending. The analytical treatment is based on Tresca’s yield criterion, its associated flow rule and a Swift-type nonlinear hardening law. Taking numerical limits, the complete solution is verified in comparison to the linear hardening solution available in the literature.     

Development of cellulose acetate based antimicrobial food packaging materials for controlled release of lysozyme

Antimicrobial packaging materials were obtained by incorporation of lysozyme into cellulose acetate (CA) films. In order to achieve controlled release of lysozyme, the structure of the films was changed from highly asymmetric and porous to dense by modulating the composition of the initial casting solution. The highest release rate, soluble lysozyme activity and antimicrobial activity were obtained with the film prepared from 5% CA solution including 1.5% lysozyme. Increasing CA content in the casting solution decreased the porosity of the films, hence, reduced the release rate, maximum released lysozyme activities and the antimicrobial activities of the films. In contrast, immobilized lysozyme activities and the tensile strength of the films increased. The incorporation of lysozyme did not cause significant reductions in tensile strength and elongation at break values except in films prepared with 15% CA. This study showed the good potential of asymmetric CA films to achieve controlled release in antimicrobial packaging.     

Solar irradiation polygon concept and application in Turkey

Classical approaches based on the Angström equation for expressing the solar global irradiation in terms of sunshine durations are abundant in the literature. However, all of them include mostly linear and to a lesser extent nonlinear relationships between these variables. The parameters in these relationships are determined invariably by the least squares technique leading to regression lines or curves as models. None of these models provides within year variations in the parameters and they are all very rigid in the application yielding to a single solar global irradiation estimate for a given sunshine duration value. This paper presents a solar irradiance polygon (SIP) concept for evaluating both qualitatively and quantitatively the within year variations in the solar energy variables. On the basis of SIPs, monthly, seasonal and annual parameters of the classical Angström equation are calculated.     

Evaluation of antioxidant and antimicrobial potential of strawberry tree (<Emphasis Type="Italic">Arbutus Unedo</Emphasis> L.) leaf

In present study, antioxidant and antimicrobial activities of strawberry tree (Arbutus unedo L.) leaves were investigated. Antioxidant activity was determined by methods of DPPH scavenging, β-carotene bleaching, reducing power, metal chelating, superoxide anion scavenging, and hydrogen peroxide scavenging activity. Total phenolic content were determined to be 197.16±1.43 mg GAE/g extract in aqueous extract. The EC₅₀ value of methanolic extracts was found to be 0.423 mg/mL. The extracts of leaves showed nearly 1/4 metal chelating capacity of standard EDTA, high reducing power, superoxide anion scavenging, and hydrogen peroxide scavenging activities. While the strawberry tree leaves exhibited antibacterial activity against Staphylococcus aureus, there was no inhibitory effect against Escherichia coli and Salmonella enteritidis. The strawberry tree leaves exhibited antifungal effect against 2 aflatoxigenic molds namely Aspergillus parasiticus NRRL 2999 and NRRL 465. These results suggest that the strawberry tree leaves may be used as an antioxidant source for pharmaceutical application, nutraceutical and functional food industries.     

Adsorption properties of a natural zeolite–water pair for use in adsorption cooling cycles

The equilibrium adsorption capacity of water on a natural zeolite has been experimentally determined at different zeolite temperatures and water vapor pressures for use in an adsorption cooling system. The Dubinin–Astakhov adsorption equilibrium model is fitted to experimental data with an acceptable error limit. Separate correlations are obtained for adsorption and desorption processes as well as a single correlation to model both processes. The isosteric heat of adsorption of water on zeolite has been calculated using the Clausius–Clapeyron equation as a function of adsorption capacity. The cyclic adsorption capacity swing for different condenser, evaporator and adsorbent temperatures is compared with that for the following adsorbent–refrigerant pairs: activated carbon–methanol; silica gel–water; and, zeolite 13X–water. Experimental results show that the maximum adsorption capacity of natural zeolite is nearly 0.12 kg_w/kg_ad for zeolite temperatures and water vapor pressures in the range 40–150 °C and 0.87–7.38 kPa.     

Effect of partial substitution of caprine milk for ovine milk,dry salting and cured scalding on lipolysis in Urfa cheeses

The objectives of this study were to determine the effect of partial substitution of caprine for ovine milk, dry salting and curd scalding on the free fatty acid (FFA) level of Urfa cheeses. At the end of storage, lauric and linoleic acids were lower in cheese made from milk where up to the 30% partial substitution of caprine milk for ovine milk was made. Dry salted cheeses had higher butyric, lauric, linoleic and linolenic acid levels, and lower palmitic acid levels than their scalded counterpart. A relative increase in short‐chain FFAs occurred during ripening. Palmitic and oleic acids were the most abundant FFAs in fresh and ripened Urfa cheeses.     

Composition of Carotenoids in <Emphasis Type="Italic">Scenedesmus protuberans</Emphasis>: Application of Chromatographic and Spectroscopic Methods

This study aimed to identify and determine the carotenoids from green microalga, Scenedesmus protuberans using analytical techniques. Identification of carotenoids was realized by comparing their absorption and mass spectral data with those of reference standards available and reported values. Chromatographic data were then combined with the spectroscopic information. The separation of carotenoids was achieved by C₃₀ column and high-performance liquid chromatography-diode array detection was used for their determination. In the present work, the carotenoid content of S. protuberans was found to be 1.45 mg/g of violaxanthin, 2.47 mg/g of all-trans-lutein, 0.15 mg/g of all-trans-α-carotene, 0.55 mg/g of all-trans-β-carotene, and 0.20 mg/g of 9 or 9′-cis-β-carotene. Due to lack of their standards, the amount of all-trans-loroxanthin and cis-isomers of other carotenoids could not be quantified. In order to validate the method, Certified Reference Material (BCR 485-Mixed vegetables) was used. In conclusion, this study can serve as a reference for the analysis of carotenoids in other microalgae.