Investigation of drag reduction performance of half NACA 0009 and 0012 airfoils placed over a trailer on the flow around truck-trailer

Journal of Mechanical Science and Technology - The drag reduction performance of a half airfoil attached to a trailer and the roof fairing at different positions was experimentally investigated in...     

Chemical changes of three native Turkish hazelnut varieties (Corylus avellana L.) during fruit development

Three native hazelnut varieties from Turkey, namely, Tombul, Palaz, and Badem, were examined for their proximate composition, minerals, and fatty acid profiles, as well as polyphenol oxidase (PPO), peroxidase (POD), and lipase activities during fruit development stages (early stage: ES, middle stage: MS, and harvest stage: HS). Proximate composition varied considerably (dry weight basis) from ES to MS. Fat was the predominant component at all stages and showed increasing trends. Six essential minerals (calcium, iron, magnesium, phosphorus, potassium, and zinc) were analysed (dry weight basis). Consuming recommended daily amount of 42.5 g hazelnut at HS supplies 23.3–25.0% of phosphorus, 11.6–18.1% of magnesium, 7.0–18.9% of iron, 4.9–8.9% of zinc, 5.1–5.7% of calcium, and 5.1–5.3% of potassium for recommended dietary allowances or adequate intake for adults. Significant (P < 0.05) decreasing trends were found in all mineral contents from early development to maturity, with some exceptions. Sixteen fatty acids were identified, among which 18:1ω9 was by far the most predominant one, followed by 18:2ω6, 16:0, and 18:0. As expected, total monounsaturated fatty acids constituted the main group of fatty acids ranging from 75.51 to 81.07% in Tombul, from 78.21 to 82.71% in Palaz, and from 73.69 to 81.65% in Badem through the maturation stages. In contrast, total polyunsaturated fatty acids showed decreasing trends from ES to HS. No significant changes (P > 0.05) were observed in total saturated fatty acids at different maturation stages. Tombul variety had the lowest PPO activity compared to those of Palaz and Badem. Badem showed highest POD activity compared to Tombul and Palaz at three stages of maturation and significant decreases (P < 0.05) in all hazelnut samples were observed in POD activity from ES to HS. No lipase activity was detected in any hazelnut samples at ES and MS, except in Badem at MS. In contrast, lipase activity was detected in all hazelnut samples at HS. These results suggest that some proximate compositions, minerals, and fatty acids gave good indications during fruit development stages, whereas enzymatic activities of PPO, POD, and lipase behaved differently among varieties and fruit development stages.     

LOW TEMPERATURE MUSHROOM (A. bisporus) DRYING WITH DESICCANT DEHUMIDIFIERS

ABSTRACT

Cultivated mushrooms (Agaricus bisporus) slices of 2·5 and 5 mm thick were dried with dehumidified air at 20°, 30° and 40°C. Rehydration ability of dried mushrooms was used as criteria for the evaluation and determination of optimum conditions. Drying mechanism of the mushroom slices was expressed by unsteady state diffusion and the results were interpreted by Fickian model. Drying temperatures lower than 40°C promoted the production of light coloured mushrooms with high rehydration ratios. Diffusivity constants were in the range of 2·6?12×l0^-11 m²/s and the activation energies varied in the range of 23·5?30·3 kJ/gmol depending on the temperature and sample thickness.     

Antioxidants alleviate electric field-induced effects on lung tissue based on assays of heme oxygenase-1, protein carbonyl content, malondialdehyde, nitric oxide, and hydroxyproline

In order to test whether antioxidants have beneficiary effects on electric field induced damage, we determined the pulmonary levels of heme oxygenase-1 (HO-1), protein carbonyl content (PCO), malondialdehyde (MDA), nitric oxide (NO) and hydroxyproline (HP) under extremely low frequency (ELF) electric (E) field exposure (50 Hz, 12 kV/m, 7 days/for 8 h/day). While PCO levels significantly increased (p < 0.05), insignificant changes (p > 0.05) were observed in HO-1, MDA, NO and HP levels for electric field exposure groups compared to the control group. We have not observed any significant change in these parameters on the electric field group compared to the group where NAC and EGCG were separately applied along with electric field. However, during our previous studies, we have concluded that NAC and EGCG are potent antioxidants and we believe that new studies should be established by way of setting up different experimental conditions.     

Natural-based polymers for antibacterial treatment of absorbent materials

In this study, polypropylene (PP) nonwoven fabric which can be used as topsheet layer of an absorbent hygienic product was modified by natural based antibacterial agents. Antibacterial herbal agents (cinnamaldehyde, geraniol, phenylethyl alcohol) were sprayed by ethanol or applied by means of polylactic acid (PLA) and polycyclohexene oxide (PCHO) based polymers prepared by three different chemical methods. Characterization of synthesized materials was conducted via thermogravimetric analysis (TGA), differential thermal analysis (DTA), and scanning electron microscopy–energy dispersive X–ray spectroscopy (SEM-EDX). Besides characterization, antibacterial and pH buffering performances of antibacterial polymers alone and on PP fabric were tested by antibacterial and pH tests. Effects of antibacterial treatments on air permeability and absorption period of nonwoven fabrics were also analyzed. According to the results, biopolymers changed the thermal stability of PP nonwoven fabric. Antibacterial performances can be ranked as cinnamaldehyde, geraniol, and phenylethyl alcohol from the best. Besides a slight decrease about liquid absorption performance, all of the treated topsheet fabrics are sufficient for an absorbent hygienic product. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48302.     

Investigation of the soil amplification factor in the Adapazari region

Turkey is located on the highly active Eurasian plate. A very active strike slip fault, the North Anatolian Fault Zone (NAFZ), crosses Turkey from east to west; earthquakes occurred on this fault on August 17, 1999 (Kocaeli) and November 12, 1999 (Düzce). Regional geology and subsoil conditions can significantly change the characteristics of ground motion. For this reason, determining soil amplification during an earthquake, especially for soft soils, is a very important topic for researchers. In this study, one dimensional ground response analyses were performed for selected Adapazari sites using the August 17, 1999 Kocaeli earthquake strong ground motion record with SHAKE2000 software. Soil characteristics and depth to engineering bedrock at the selected sites are different and the observed level of structural damage at these sites during the Kocaeli earthquake was also different. Calculated soil surface response spectrums at these sites were compared with the recommended design spectra of the Turkish Earthquake Code and the Eurocode 8. According to one dimensional ground response analyses, the calculated response spectra of the selected sites exceed the recommended design spectra of the Turkish Earthquake Code and the Eurocode 8. Calculations show that higher amplification ratios occur at higher periods due to soil behaviour. Results of this study indicate that local geological conditions may amplify ground motion at some periods and, due to this amplification, the calculated response spectra may exceed the recommended design spectra. Therefore, it is clear that local site conditions must be considered for earthquake-resistant engineering designs on soft alluvial soil deposits.     

Use of o-phenylene dioxydiacetic acid impregnated in Amberlite XAD resin for separation and preconcentration of uranium(VI) and thorium(IV)

The impregnation of o-phenylene dioxydiacetic acid (OPDA) into a polymeric matrix, Amberlite XAD-2000, is reported and was characterized by infrared spectroscopy. The amount of attached OPDA to the polymer resin was found to be 1.77mmolg(-1) resin. The resin was used for the sorption of U(VI) and Th(IV) from aqueous solution. This sorbent was capable of preconcentrating U(VI) and Th(IV) from weakly acidic or neutral solution. The retained metals were eluted sequentially using 0.25molL(-1) HCl for U(VI) and 1molL(-1) HCl for Th(IV) and determined spectrophotometrically using arsenazo-(III). The capacity of the resin for U(VI) and Th(IV) was found to be 0.121 and 0.113mmolg(-1), respectively. The impregnated resin exhibits a high chemical stability, reusability and fast equilibration. The method was used for the determination of U(VI) and Th(IV) in synthetic samples and rock samples.     

EFFECT OF INITIAL MOISTURE CONTENT ON THE THIN LAYER DRYING CHARACTERISTICS OF HAZELNUTS DURING ROASTING

ABSTRACT

Effect of initial moisture content on the thin layer drying characteristics of hazelnuts during roasting was described for a temperature range of 100-160°C, using several thin layer equations. The effective diffusivity varied from 2.8×10^?7 to 21.5×10^?7m²/s over the temperature and moisture range. Temperature dependence of the diffusivity coefficient was described by Arrhenius-type relationship. The activation energy for moisture diffusion was found to be 2703 kJ/kg, 2289 kJ/kg and 2030 kJ/kg for the initial moisture content of 12.3% db, 6.14% db, and 2.41% db, respectively. Two-term equation gave better predictions than Henderson and Pabis and Thompson equations, and satisfactorily described thin layer drying characteristics of hazelnut roasting. A generalised mathematical model with the linear temperature dependence for moistured, non-treated and pre-dried hazelnuts were also developed.     

Microstructural characterization of corn starch‐based porous thermoplastic composites filled with multiwalled carbon nanotubes

Microstructural characterization of corn starch‐based porous thermoplastic (TPS) composites containing various contents (0.1, 0.5, and 1 wt %) of multiwalled carbon nanotubes (MWCNTs) was performed. Corn starch was plasticized with a proper combination of glycerol and stearic acid. TPS composites with MWCNT were prepared conducting melt extrusion followed by injection molding. TPS containing 1 wt % of MWCNTs exhibited higher tensile strength and elastic modulus values than neat TPS. Moreover, TPS electrical conductivity was determined to increase with increasing content of MWCNTs. X‐ray diffraction measurements revealed that incorporation of MWCNTs increased the degree of TPS crsystallinity to some extent. Scanning electron microscopy examination revealed that MWCNT altered TPS surface morphology and tensile failure modes, significantly. Transmission electron microscopy investigation showed that dispersion characteristics of MWCNTs within TPS were in the form of tiny clusters around micro pores of TPS, which is considered influential on electrical conductivity of the resulting composites. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013