Effect of Extraction Methods on the Properties of Althea Officinalis L. Fibers

In this study, the effect of extraction methods on the properties of Althea officinalis l. (marshmallow) fibers was investigated. For this purpose, obtaining the fibers from stem was done by water and chemical extraction. After the extraction process, mechanical and thermal properties of althea fibers were investigated and morphological structure was examined. Crystallinity indexes (CI) of fibers were determined. Scanning electron microscopy results revealed that extraction of althea officinalis fibers by alkali boiling in 5% NaOH solution led to removal of surface impurities and also according to X-ray diffraction results, crystallinity index of fibers was improved by 14%. Chemically extracted fibers showed 37% higher tensile strength when compared to water extracted fibers. Density measurements revealed that chemically retted fibers have higher density. Also, Fourier Transform Infrared Spectroscopy analysis showed that chemical extraction caused change of chemical composition by decreasing and/or disappearing of some peaks which belong to hemicellulose and lignin.     

Multivariate Statistical Analysis of Data and ICP-MS Determination of Heavy Metals in Different Brands of Spices Consumed in Kayseri,Turkey

The concentrations of Cr, Mn, Fe, Co, Ni, As, Cd, Pb, and Zn in 19 different spices from 11 different brands (in total 69 samples) collected from Kayseri, Turkey, were determined by inductively coupled plasma mass spectrometry (ICP-MS) after microwave digestion. Multivariate and univariate statistical techniques such as principal component analysis (PCA), cluster analysis (CA), correlation analysis, and one way ANOVA were applied for the interpretation of the obtained data. Three principal components explain 79.6% of the total variance. They are as follows: PC1 with Cr, Fe and Pb; PC2 with Mn, As, and Cd; and PC3 with Ni and Co. The spices were classified into their different types and brands by PCA and CA. The certified reference material (GBW07605 Tea Leaves) was analyzed to confirm the accuracy of the method.     

Microstructural,mechanical, and electrical characterization of directionally solidified Al–Cu–Mg eutectic alloy

The composition of an Al–Cu–Mg ternary eutectic alloy was chosen to be Al–30 wt% Cu–6 wt % Mg to have the Al₂Cu and Al₂CuMg solid phases within an aluminum matrix (α-Al) after its solidification from the melt. The alloy Al–30 wt % Cu–6 wt % Mg was directionally solidified at a constant temperature gradient (G = 8.55 K/mm) with different growth rates V, from 9.43 to 173.3 μm/s, by using a Bridgman-type furnace. The lamellar eutectic spacings (λ_E) were measured from transverse sections of the samples. The functional dependencies of lamellar spacings λ_E (\({\lambda _{A{l_2}CuMg}}\) and \({\lambda _{A{l_2}Cu}}\) in μm), microhardness H _V (in kg/mm²), tensile strength σ_T (in MPa), and electrical resistivity ρ (in Ω m) on the growth rate V (in μm/s) were obtained as \({\lambda _{A{l_2}CuMg}} = 3.05{V^{ - 0.31}}\), \({\lambda _{A{l_2}Cu}} = 6.35{V^{ - 0.35}}\), \({H_V} = 308.3{\left( V \right)^{ - 0.33}}\); σ_T= 408.6(V)^0.14, and ρ = 28.82 × 10^–8(V)^0.11, respectively for the Al–Cu–Mg eutectic alloy. The bulk growth rates were determined as \(\lambda _{A{l_2}CuMg}^2V = 93.2\) and \(\lambda _{A{l_2}Cu}^2V = 195.76\) by using the measured values of \({\lambda _{A{l_2}CuMg}}\), \({\lambda _{A{l_2}Cu}}\) and V. A comparison of present results was also made with the previous similar experimental results.     

Investigation of wind shear coefficients and their effect on electrical energy generation

Wind measurements are generally performed below wind turbine hub heights due to higher measurement and tower costs. In order to obtain the wind speed at the hub height of the turbine, the measurements are extrapolated, assuming that the wind shear is constant. This assumption may result in some critical errors between the estimated and actual energy outputs. In this paper wind data collected in Bal?kesir from October 2008 to September 2009, has been used to show the effects of wind shear coefficient on energy production. Results of the study showed that, the difference between wind energy production using extrapolated wind data and energy production using measured wind data at hub height may be up to 49.6%.     

Comparison of ASCE/SEI Standard and modal pushover-based ground motion scaling procedures for pre-tensioned concrete bridges

Complex analysis methods such as non-linear time-history analyses (NTHA) are often required for the design of non-standard bridges. The selection of the ground motions for the NTHA is a crucial task as the results of the analyses show a wide variability according to the selected records. In order to predict the demand in accordance with the seismic hazard conditions of the site, the selected motions are usually modified by scaling procedures. Within this context, the performance of two scaling methods, namely the Modal Pushover Based Scaling (MPS) and ASCE/SEI procedures, are compared for the NTHA of a large bridge, the Demirtas Viaduct (longitude 29.10°, latitude 40.28°), in this study. The system comprised of 28 spans was idealised with two different analytical models in order to assess the effect of the modelling on the scaling procedures results. The effects of the hazard level on the scaling results were evaluated. The required number of motions for conducting effective analyses, i.e. the minimum number of motions for estimating the target goals, was investigated at different hazard levels. MPS reduced the dispersion considerably more than the ASCE scaling, indicating sets can be formed with fewer motions to predict the target levels.     

Water-in-Water Emulsion Based Synthesis of Hydrogel Nanospheres with Tunable Release Kinetics

Poly(ethylene glycol) (PEG) micro/nanospheres have several unique advantages as polymer based drug delivery systems (DDS) such as tunable size, large surface area to volume ratio, and colloidal stability. Emulsification is one of the widely used methods for facile synthesis of micro/nanospheres. Two-phase aqueous system based on polymer–polymer immiscibility is a novel approach for preparation of water-in-water (w/w) emulsions. This method is promising for the synthesis of PEG micro/nanospheres for biological systems, since the emulsion is aqueous and do not require organic solvents or surfactants. Here, we report the synthesis of nano-scale PEG hydrogel particles using w/w emulsions using phase separation of dextran and PEG prepolymer. Dynamic light scattering (DLS) and scaning electron microscopy (SEM) results demonstrated that nano-scale hydrogel spheres could be obtained with this approach. We investigated the release kinetics of a model drug, pregabalin (PGB) from PEG nanospheres and demonstrated the influence of polymerization conditions on loading and release of the drug as well as the morphology and size distribution of PEG nanospheres. The experimental drug release data was fitted to a stretched exponential function which suggested high correlation with experimental results to predict half-time and drug release rates from the model equation. The biocompatibility of nanospheres on human dermal fibroblasts using cell-survival assay suggested that PEG nanospheres with altered concentrations are non-toxic, and can be considered for controlled drug/molecule delivery.