The fate of ochratoxin A during the Pekmez production from mouldy grapes

The grape juices produced from mouldy grapes that are contaminated naturally with OA between 2.1 and 9.8 μg/l were used in pekmez production. In the processing steps of pekmez, changes in OA amount were examined. The amounts of OA in pekmez samples were found to be 5–6 times higher than OA amount of grape juice.

The dry matter (%), total sugar (%) and pH values were 18.93, 17.82 and 3.36 at the beginning of the experiment while they were 71.42, 67.35 and 3.91 at the end of the experiment, respectively.     

Two-dimensional natural convection in a porous triangular enclosure with a square body

A two-dimensional numerical solution for steady-state buoyancy induced convection in a right-triangular enclosure with a square body is obtained using finite difference technique. The solid body is located far from the origin with the distance of 0.3 in both directions. It is considered that the temperature of the bottom wall of triangular enclosure is higher than that of inclined wall while the vertical wall is insulated. To obtain the effects of the presence of a square body on heat transfer and fluid flow inside the enclosure, four different temperature boundary conditions were applied for the body as heated, cooled, neutral and adiabatic at different Ra numbers. It is observed that fluid flow and temperature fields strongly depend on thermal boundary conditions of the body.     

Estimating the uniaxial compressive strength of a volcanic bimrock

Preparation of the standard sized cores from geological mixtures or fragmented rocks such as mélanges, fault rocks, coarse pyroclastic rocks, breccias and sheared serpentinites is often extremely difficult. Therefore, determination of the mechanical parameters such as cohesion, friction angle and UCS is extraordinarily difficult for these types of rocks. This paper presents the results of studies using Ankara Agglomerate to develop an empirical approach for the determination of the UCS for a volcaniclastic mixture of strong andesite blocks within weak tuff matrix, formed from the aggregation of volcanically exploded rock debris mixed with ash fall (tuff), i.e. a bock-in-matrix rock or ‘bimrock’. The uniaxial compressive strength of a volcanic bimrock can be predicted using the conceptual approach within as-yet poorly understood error limits. Therefore, the approach introduced is open to improvement depending on the number of data and cases including different type of bimrocks.     

Rock rupture phenomenon and pillar failure in tuffs in the Cappadocia region (Turkey)

The aim of this study is to investigate the relation between the critical failure stresses for rupture and pillar instabilities observed in tuffs in Cappadocia region and stresses triggering the early crack propagation stages such as crack initiation, systematic cracking and crack coalescence thresholds determined from Brazilian and uniaxial compression tests on rock samples obtained from these instabilities. These failures in the region have been occurring as a result of strength reduction of rocks through time, and long-term strengths of these rocks are achieved by own weight of the rock mass. In this study, these failures were evaluated in order to estimate long-term failure strength of rocks by classical short-term laboratory tests. For this purpose, some cases on rock rupture phenomenon and a pillar failure case were picked from different parts of the region. During the selection of these instabilities, the ones with relatively regular geometries were preferred. Rock block samples were collected from each case, and uniaxial compressive and indirect tensile (Brazilian) tests were carried out on dry and saturated specimens. In these tests, axial deformations and acoustic emission (AE) activity were also recorded in order to identify thresholds of the crack propagation and deformation stages of rock samples. The simplified back-analysis of each case was conducted, and the tensile stresses on rupture surfaces and uniaxial compressive stress on pillar were calculated. Then, stress levels at the thresholds of crack propagation and deformation stages determined by laboratory tests and stress levels determined by back-analyses were compared. Finally, it is concluded that crack initiation and/or systematic cracking thresholds may be a good indicator to determine lower bound of the in-situ strength of these tuffs and can be used as an estimator of their long-term strengths.     

An investigation on the mechanisms of instabilities and safe design of the south slope at a lignite pit (SW Turkey) based on a sensitivity approach

Turkey has significant lignite reserves which are generally being extracted using open pit mining methods. The Hüsamlar pit is one of the operated lignite pits in the well-known Mugla lignite province in SW Turkey. Some local failures and one large failure, which caused the evacuation of the Hüsamlar village located next to the slope crest and interruption in coal production, occurred along the south slope of this pit. This paper outlines the results of the field and laboratory geotechnical investigations associated with the causes and mechanisms of the instabilities, and assessments on the possible modifications in the current and planned final slope geometries to improve the stability of the south slope. Since no sufficient data on groundwater conditions in the pit were available, in order to reduce the uncertainty associated with groundwater, different pore pressure ratios (r _u) were considered and a sensitivity approach was used in the stability assessments. The back-analyses of the observed instabilities including one or more benches in the overburden indicated that the most critical modes of failure for the south slope are circular and composite sliding surfaces. Although kinematical analyses suggested that structurally controlled failures would not be expected, one local planar failure that occurred in the south slope emphasizes that the possibility of local planar sliding should be considered when the dip of bedding planes locally exceed 20° and pore pressure becomes high. In addition, the back-analyses revealed that r _u was probably between 0.3 and 0.4 and the residual shear strength along the bedding planes was critical when slope instabilities occurred along the south slope. The stability assessments for the current and the final south slope, which was planned by the mining organization operating the pit, indicated that some modifications in bench and slope geometries are necessary to achieve a factor of safety of 1.3, which is a commonly used value in open pit practice. In addition, these assessments also suggested that the most critical zone in the overburden was the thinly bedded marl in terms of stability, and at the thickest part of this material (30 m), the overall slope angles satisfying F = 1.3 at r _u values of 0.2, 0.3 and 0.4 should be 18°, 17° and 15°, respectively. Except those in the thinly bedded marl, bench widths in the overburden units and coal seam are reduced and steeper slopes with F ≥ 1.3 were achieved.     

Dye-Surfactant interaction in the premicellar region

The interaction of safranin-O (SO), a cationic dye, with anionic surfactants [sodium dodecylsulfate (SDS) and sodium dodecylsulfonate (SDSo]) having the same hydrophobic group but different polar groups was studied spectrophotometrically in the premicellar region far below the critical micelle concentration in aqueous media using the method of continuous variations, also called Job's Method. This method was applied to determine the equilibrium complex formation constant (K) as well as the molecular complex formation ratio. Both SDS and SDSo formed stable associations with SO, and the molecular complex formation ratio was determined as 1:1. The data obtained from Job's Method indicated that the equilibrium complex formation constant of SDS is higher than that of SDSo. We also studied the influence of cosolvents such as methanol, dimethylformamide (DMFA), and dioxan (DX) on molecular complex formation between SDS and SO, and observed that the presence of cosolvents inhibited molecular complex formation. This inhibitory effect of cosolvents on molecular complex formation followed the order of methanol>DMFA>DX.     

Prolonged skin retention of clobetasol propionate by bio-based microemulsions: a potential tool for scalp psoriasis treatment

Novel effective and cosmetically acceptable formulations are needed for the treatment of scalp psoriasis, due to the poor efficacy of the current products. The challenge in developing safe, efficient, and convenient delivery systems for this drug was addressed in the present work by formulating clobetasol propionate-loaded W/O microemulsions (MEs). Pseudo-ternary phase diagrams were constructed by using a combination of biocompatible and biodegradable excipients. Characterization studies demonstrated that selected MEs had suitable technological features such as being Newtonian fluids, possessing low viscosity, and high thermodynamic stability. Photomicrographs showed a significant alteration of the skin structure after treatment with MEs, and a preferential concentration of these in the stratum corneum and epidermis. These data, together with ex vivo permeation results, suggested an enhanced topical targeted effect due to an increased drug retention efficacy in the upper skin layers, as desired. Moreover, the bio-based excipients selected could contribute to the healing of the psoriatic scalp. In this way, the improvement of clobetasol efficacy is combined with the useful properties of the microemulsion components and with environmental safety.     

Tuning shades of white light with multi-color quantum-dot-quantum-well emitters based on onion-like CdSe-ZnS heteronanocrystals

We present white light generation controlled and tuned by multi-color quantum-dot-quantum-well emitters made of onion-like CdSe/ZnS/CdSe core/shell/shell heteronanocrystals integrated on InGaN/GaN light-emitting diodes (LEDs). We demonstrate hybrid white LEDs with (x, y) tristimulus coordinates tuned from (0.26, 0.33) to (0.37, 0.36) and correlated color temperatures from 27?413 to 4192?K by controlling the number of their integrated red-green-emitting heteronanocrystals. We investigate the modification of in-film emission from these multi-layered heteronanocrystals with respect to their in-solution emission, which plays a significant role in hybrid LED applications. Our proof-of-principle experiments indicate that these complex heteronanocrystals hold promise for use as nanoluminophors in future hybrid white LEDs.     

Evaluation of SPEEK/PBI blend membranes for possible direct borohydride fuel cell (DBFC) application

Direct Borohydride Fuel Cell (DBFC) is one of the most promising liquid fuel cell technologies. However, similar to the other classes of fuel cells, there are technical problems to be solved and new materials specific to the technology should be developed for each component. The electrolyte membrane is one of the key components for its success similar to the other FC types. Commercial perfluorosulfonic acid type membranes namely Nafion^® is still the first choice in relatively less number of DBFC studies. In this study, less costly blend membranes were fabricated and characterized for comparison of the key properties with Nafion^® especially for DBFC application. For this purpose, the selected base polymer poly ether-ether-ketone (PEEK) was sulfonated up to high degrees of sulfonation (DS) and blended with another base polymer polybenzimidazole (PBI) at various ratios. Key electrolyte membrane properties such as DS, water uptake, ionic conductivity, BH₄⁺ fuel crossover, mechanical strength and glass transition temperature (T_g) were investigated by proton nuclear magnetic resonance spectroscopy (H NMR), electrochemical impedance spectroscopy (EIS), voltammetry, universal testing machine and Differential Scanning Calorimetry (DSC) respectively. Finally single cell test performances were investigated in a DBFC test system. Results showed that the mechanical strength of SPEEK which has a good ionic conductivity value could be improved well beyond the value of Nafion 117 without sacrificing too much of the conductivity. It has been observed that there is a trade-off between the important properties such as ionic conductivity, fuel (borohydride) permeability and mechanical strength at the first sight. The peak power densities obtained for blend membranes are close to the value of the commercial Nafion^® 117 membrane. These results show that these blend membranes have a potential that can be improved for direct borohydride fuel cells.