Antioxidant and anticholinesterase evaluation of selected Turkish Salvia species

Since Salvia species (Lamiaceae) have been recorded to be used against memory loss in European folk medicine, we herein examined in vitro anticholinesterase and antioxidant activities of 56 extracts prepared with petroleum ether, chloroform, ethyl acetate and methanol obtained from 14 Salvia species (Salvia albimaculata Hedge and Hub, Salvia aucheri Bentham var. canescens Boiss and Heldr, Salvia candidissima Vahl. ssp. occidentalis, Salvia ceratophylla L., Salvia cryptantha Montbret and Bentham, Salvia cyanescens Boiss and Bal., Salvia frigida Boiss, Salvia forskahlei L., Salvia halophilaHedge, Salvia migrostegia Boiss and Bal., Salvia multicaulis Vahl., Salvia sclarea L., Salvia syriaca L., Salvia verticillata L. ssp. amasiaca) growing in Turkey. The antioxidant activities were assessed by both chemical and enzymatic methods against 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging and xanthine/xanthine oxidase (XO) system generated superoxide anion radical inhibition. Anticholinesterase effect of the extracts was tested against both acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) at concentrations of 0.2 and 1 mg/ml using a microplate-reader assay based on the Ellman method. Most of the extracts did not show any activity against AChE at 0.2 mg/ml, while the chloroform extracts had noticeable inhibition against BChE between 47.7% and 74.7%. The most active extracts at 1 mg/ml for AChE inhibition were observed to be petroleum ether extract of Salvia albimaculata (89.4%) and chloroform extract of Salvia cyanescens (80.2%), whereas ethyl acetate extracts of Salvia frigida and Salvia migrostegia, chloroform extracts of Salvia candidissima ssp. occidentalis and Salvia ceratophylla, as well as petroleum ether extract of Salvia cyanescens were found to inhibit potently BChE (92.2%, 89.6%, 91.1%, 91.3%, and 91.8%, respectively). Particularly, the ethyl acetate and methanol extracts were observed to be highly active against both DPPH and XO. Our data indicates that nonpolar extracts of Salvia species for anticholinesterase activity and the polar extracts for antioxidant activity are worth further phytochemical evaluation for identifying their active components.     

Cost effect of earthquake region and soil type for office buildings in Turkey

In this study, the change in the load-bearing system cost of a reinforced concrete office building has been investigated in relation to the earthquake regions and soil types. Three different office projects each with five stories were investigated. The structural design calculations have been made according to four different soil types and four different earthquake regions. According to each combination, concrete, steel and formwork adopted approximations were calculated to reach the rough cost of each office building. The changes in the cost of projects according to the soil type and earthquake region were examined with multiple regression analysis and analysis of variance. In general, the change in cost has been observed around 22% between first and fourth soil type and 14% between first and fourth earthquake region.     

The effect of par‐baking and frozen storage time on the quality of cup cake

The effects of frozen storage and initial baking time of par‐baked cake on baking loss, volume, moisture, colour and textural properties of cake obtained after thawing and rebaking were investigated. Cakes, par‐baked at 175 °C for 15, 20 and 25 min, were stored at ?18 °C for 3, 6 and 9 months. After storage, par‐baked cakes were thawed and rebaked at 175 °C for 10, 15 and 20 min. Baking loss, moisture content, L and +b colour values, firmness, gumminess and chewiness of the resulting full‐baked cakes were significantly affected by both par‐baking and frozen storage time, while specific volume, cohesiveness, springiness and resilience values were significantly affected by frozen storage time. The increase in the time of frozen storage of the par‐baked cake leads to a decrease in the quality of the rebaked cake, namely an increase of baking loss and cake crumb firmness, and a loss in the moisture content and specific volume. Moisture of cake crumb, L and +b colour values, firmness, gumminess and chewiness significantly increased as the par‐baking time increased. However, regarding baking loss, specific volume, moisture content and textural properties, 3‐month intermediate storage at ?18 °C and 20‐min initial baking time gave the best result among the cakes produced by using the two‐step baking procedure.     

Properties of sol–gel synthesized n-ZnO/n-GaN (0001) isotype heterojunction

The electronic and optical properties of sol–gel synthesized n-ZnO/n-GaN (0001) isotype heterojunction were reported. By incorporating ZnO–GaN with the same wurtzite structure and the similar lattice constant, a heterojunction was fabricated. The junction properties were evaluated by measuring the electrical characteristics. The n-ZnO/n-GaN heterostructure exhibits a non-ideal I–V behavior with the ideality factor greater than unity that could be ascribed to the interfacial layer, interface states and series resistance. The forward turn on voltage is about 0.7 V and the reverse breakdown voltage is more than 2 V. The optical band gaps of the ZnO film and GaN using optical absorption method were found to be 3.272 eV and 3.309 eV, respectively. The fundamental absorption edge in the film is formed by the direct allowed transitions.     

The elasto-plastic impact analysis of functionally graded circular plates under low-velocities

In this study, three-dimensional elasto-plastic analysis of functionally graded (FG) circular plates under low-velocity impact loads is presented. The FG circular plate is composed of ceramic (SiC) and metal (Al) phases, varying in a predetermined fashion through the plate thickness. The elasto-plastic behaviour of the FG circular plate is described by the TTO model. In the analyses, the ceramic phase is taken to be an isotropic elastic material whereas the metal phase is taken to be elasto-plastic material in accordance with the TTO model. The locally effective material properties were evaluated using homogenization method which is based on the Mori–Tanaka scheme. The effects of compositional gradient exponent and impactor velocity on the elasto-plastic impact response of the FG circular plates are investigated, and results are presented graphical form. The compositional gradient exponent and impactor velocity have significant effects on the elasto-plastic impact response of the FG circular plates. The elasto-plastic impact response of FG circular plates is similar to those of homogeneous plates. Therefore, the TTO model can be used to describe the mechanical behaviour of FG plates beyond the elastic range, assuming that the material response is essentially governed by the spreading of plasticity in the metal phase.     

Adsorptive removal of phenol from aqueous solutions on activated carbon prepared from tobacco residues: equilibrium, kinetics and thermodynamics

This study consists of producing high surface area activated carbon from tobacco residues by chemical activation and its behavior of phenol removal from aqueous solutions. K(2)CO(3) and KOH were used as chemical activation agents and three impregnation ratios (50, 75 and 100 wt.%) were applied on biomass. Maximum BET surface areas of activated carbons were obtained from impregnation with 75 wt.% of K(2)CO(3) and 75 wt.% of KOH as 1635 and 1474 m(2)/g, respectively. Optimum adsorption conditions were determined as a function of pH, adsorbent dosage, initial phenol concentration, contact time and temperature of solution for phenol removal. To describe the equilibrium isotherms the experimental data were analyzed by the Langmuir, Freundlich, Dubinin-Radushkevich (D-R) and Temkin isotherm models. Pseudo-first order, pseudo-second order and intraparticle diffusion kinetic models were used to find out the kinetic parameters and mechanism of adsorption process. The thermodynamic parameters such as ΔG°, ΔH° and ΔS° were calculated for predicting the nature of adsorption. According to the experimental results, activated carbon prepared from tobacco residue seems to be an effective, low-cost and alternative adsorbent precursor for the removal of phenol from aqueous solutions.     

Insights into research on phytochemistry and biological activities of Prunus armeniaca L. (apricot)

Prunus armeniaca L. (Rosaceae) is an important medicinal edible plant species commonly known as “apricot”. Apricot is one of the most delicious and commercially traded fruits in the world. The plant is rich in mono- and polysaccharides, polyphenols, fatty acids and sterol derivatives, carotenoids, cyanogenic glucosides, and volatile components due to its appealing smell. P. armeniaca has been also investigated for various biological activities such as antimicrobial, antimutagenic, inhibitory activity against several enzymes, cardioprotective, anti-inflammatory and antinociceptive as well as antioxidant activity. Among these activities, antioxidant activity of apricot has been studied extensively and the plant displayed a high antioxidant effect in both in vitro and in vivo test systems. In this review, the relevant literature summary is given on phytochemistry and biological activity reports published on apricot. The literature survey for this review was performed using the key words “Prunus armeniaca and apricot” through the search Scopus, ScienceDirect, Pubmed, and Web of Science data bases between 1950 and 2010.     

Determining optimum tilt angles and orientations of photovoltaic panels in Sanliurfa, Turkey

The performance of a photovoltaic (PV) panel is affected by its orientation and its tilt angle with the horizontal plane. This is because both of these parameters change the amount of solar energy received by the surface of the PV panel. A mathematical model was used to estimate the total solar radiation on the tilted PV surface, and to determine optimum tilt angles for a PV panel installed in Sanliurfa, Turkey. The optimum tilt angles were determined by searching for the values of angles for which the total radiation on the PV surface was maximum for the period studied. The study also investigated the effect of two-axis solar tracking on energy gain compared to a fixed PV panel. This study determined that the monthly optimum tilt angle for a PV panel changes throughout the year with its minimum value as 13° in June and maximum value as 61° in December. The results showed that the gains in the amount of solar radiation throughout the year received by the PV panel mounted at monthly optimum tilt angles with respect to seasonal optimum angles and tilt angel equal to latitude were 1.1% and 3.9%, respectively. Furthermore, daily average of 29.3% gain in total solar radiation results in an daily average of 34.6% gain in generated power with two-axis solar tracking compared to a south facing PV panel fixed at 14° tilt angle on a particular day in July in Sanliurfa, Turkey.     

Polymer-immobilized palladium supported on TiO2 (Pd-PVB-TiO2) as highly active and reusable catalyst for hydrogen generation from the hydrolysis of unstirred ammonia-borane solution

Herein we report the preparation, characterization and the catalytic use of the polymer-immobilized palladium catalyst supported on TiO₂ (Pd-PVB-TiO₂) in the hydrolysis of unstirred ammonia-borane solution. The polymer-immobilized palladium catalyst is stable enough to be isolated as solid materials and characterized by XRD, SEM, and EDX. The immobilized palladium catalyst supported on TiO₂ is found highly active, isolable, and reusable in the hydrolysis of unstirred ammonia-borane even at low concentrations and temperature. The work reported here also includes the full experimental details for the collection of a wealth of kinetic data to determine the activation energy (E_a = 55.9 kJ/mol) and the effects of catalyst and substrate concentration on the rate for the hydrolysis of unstirred ammonia-borane solution. Maximum H₂ generation rate of ∼642 mL H₂ min⁻¹ (g Pd)⁻¹ and ∼4367 mL H₂ min⁻¹ (g Pd)⁻¹ was measured by the hydrolysis of AB at 25 °C and 55 ± 0.5 °C, respectively.