Drying and rehydration behaviors of green bell peppers

In this study, the drying behaviors of green bell peppers were examined in convection dryer. The study was carried out for 3 drying temperatures (55, 65, and 75°C) and for pre-treated samples with ethyl oleate solution against control samples. The pre-treated samples dried faster than the control ones. Drying time decreased with an increase of drying temperature. Rehydration ratio of the pre-treated samples was higher than control samples. Moisture transfer from green bell peppers was described by applying the Fick’s diffusion model and the effective moisture diffusivity (D _eff ) was calculated. The D _eff values for pre-treated and control samples varied between 0.705 and 2.618×10⁻⁹ m²/sec. Activation energy values for moisture diffusion ranged from 41.67 and 52.99 kJ/mol. Drying data was fitted to 4 thin-layer drying models, namely, Lewis, Henderson and Pabis, logarithmic, and Page. The best model, which best represented the green bell peppers drying, was logarithmic.     

Fatty acids of neutral and phospholipids of three endangered trout: Salmo trutta caspius Kessler, Salmo trutta labrax Pallas and Salmo trutta macrostigma Dumeril

Total (TL), neutral (NL) and phospholipid (PL) amounts and fatty acid (FA) composition of female Salmo trutta caspius, Salmo trutta labrax and Salmo trutta macrostigma were investigated during one year. Twenty-three FAs were identified in both NLs and PLs. The principal FAs of both fractions were palmitic acid in saturated fatty acid, oleic acid in monounsaturated fatty acid, docosahexaenoic acid (DHA) in n-3 polyunsaturated fatty acids (n-3 PUFAs) and linoleic acid in n-6 PUFAs. The highest values for TLs, NLs and PLs were found in winter. As a general trend, the highest n-3/n-6 ratios and eicosapentaenoic acid (EPA) + DHA amounts were found in the winter and this coincided with the lowest gonado-somatic index.     

Determination of optimal production parameters for polyacrylonitrile nanofibers

The object of this work is to determine the most suitable values of process and solution parameters for electrospinning of polyacrylonitrile (PAN) nanofibers including solution concentration, applied voltage, and working distance between the needle tip and the collector plate. To investigate the effects of those parameters on the fiber morphology, nanofiber mat samples were produced by changing the value of parameters systematically. The scanning electron microscope images of these samples were analyzed to realize the effects of these parameters on the nanofiber morphology. Our results demonstrate that the diameter of the fibers increases with increasing concentration. However, the diameter reduces as the applied voltage and working distance between needle tip and the collector increase up to a certain value. In addition to this, viscosity and applied voltage have a strong effect on the uniformity and morphology of the nanofibers. Moreover, a relationship between spinning distance, voltage supplied, solution concentration, charge density, bead formation, and the diameter of the electrospun PAN nanofiber were established in the study. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Influences of metallic Co and mechanical alloying on the microstructural and mechanical properties of TiB2 ceramics prepared via pressureless sintering

This study reports the influences of metallic cobalt (Co) and mechanical alloying (MA) on the microstructural and mechanical properties of TiB₂ ceramics prepared by using a combined method of cold pressing and sintering. The effects of Co addition (0, 5, 10 and 20 wt.%) and mechanical alloying duration (0, 3, 6 and 9 h) on the properties of TiB₂ ceramics were investigated. MA experiments were carried out in a Spex? 8000D Mixer/Mill and milled powders were subsequently compacted to cylindrical preforms by uniaxial pressing at 400 MPa. The green compacts were sintered in a controlled atmosphere at 1550 °C for 1 h. Phase and microstructural characterizations of the mechanically alloyed (MA’d) and sintered samples were performed by X-ray diffractometer (XRD), optical microscope (OM) and scanning electron microscope (SEM). Density measurements were conducted using Archimedes method. Vickers hardness, elastic modulus and fracture toughness of the sintered samples were measured using Indentation technique.     

Synthesis and characterization of aromatic and aliphatic ether bridged polymers containing carbazole moieties

In this study, the polymers were synthesized ether bridged containing carbazole moieties via HBr elimination. Also, these polymers include the aliphatic chains at the different lengths and aromatic groups in their structures. However, the polymers were characterized by FT-IR, NMR and UV–vis spectroscopy, and their thermal stabilities were determined via TGA measurements. Fluorescence measurements were performed using N,N′-dimethyl formamide solutions and also, the optimization of the concentrations to obtain maximal emission intensity was investigated in N,N′-dimethyl formamide. The morphologic properties of the polymers were investigated at different particle sizes by using Scanning Electron Microscopy (SEM). Additionally, the number average molecular weight (M_n), weight average molecular weight (M_w) and polydispersity index (PDI) values of the polymers were determined by size exclusion chromatography (SEC) technique. Resultantly, the remarkable properties related to the fluorescence and thermal measurements of the polymers were obtained. Therefore, these polymers could be used in various application fields because of the fluorescent and thermal properties.     

Effect of basic pumice on morphologic properties of interfacial transition zone in load-bearing lightweight/semi-lightweight concretes

The objective of this research is to determine the effect of basic pumice on morphologic properties of interfacial transition zone in load-bearing lightweight/semi-lightweight concretes. In this respect, it has been researched how the chemical and physical structure and the volumetric ratio of basic pumice affected the following three morphologic properties of interfacial transition zone: compactness, width and physical adherence. In accordance with the stated purpose, 15 concrete serials with various properties were produced using basic pumice as aggregate and 670 images were taken from the samples collected from these serials via scanning electron microscope (SEM). Semi-analytical detections were performed based on non-generalizing numeric data obtained in conclusion of the determination of grain limits in these images and comments on visual analysis. In accordance with these detections, it has been concluded that the basic pumice has a high level of potential to contribute to the morphologic properties of interfacial transition zone.     

Influence of high temperature on the properties of concretes made with industrial by-products as fine aggregate replacement

Influence of high temperature on the properties of concrete containing non-ground granulated blast-furnace slag (GBFS) and coal bottom ash (BA) as fine aggregate was presented. Six series of concrete mixtures were prepared by partially replacing fine aggregate separately with GBFS and BA. Replacement percentages were between 10 and 50% with an increment of 10% by dry weight of fine aggregate. Then 0.2% polypropylene fibres (PP) were added to last three mixtures that has the same mixture with the first three series. The first series is control concrete, the second series contained GBFS and the third series contained BA. All the concrete specimens were exposed to 800 °C temperature at the age of 90 days. Tests were conducted to determine loss in weight, compressive strength, and dynamic modulus of elasticity. Also surface crack observations were conducted with microscope. Test results showed that it is possible to partially replace fine aggregate with GBFS or BA even if such concretes were to be subjected to high temperature response. Performance of BA concrete was found to be better than GBFS as replacement material.