Modeling with ANN and effect of pumice aggregate and air entrainment on the freeze–thaw durabilities of HSC

The objective of this work is to calculate the compressive strength, ultrasound pulse velocity (UPV), relative dynamic modulus of elasticity (RDME) and porosity induced into concrete during freezing and thawing. Freeze–thaw durability of concrete is of great importance to hydraulic structures in cold areas. In this paper, freezing of pore solution in concrete exposed to a freeze–thaw cycle is studied by following the change of concrete some mechanical and physical properties with freezing temperatures. The effects of pumice aggregate (PA) ratios on the high strength concrete (HSC) properties were studied at 28 days. PA replacements of fine aggregate (0–2 mm) were used: 10%, 20%, and 30%. The properties examined included compressive strength, UPV and RDME properties of HSC. Results showed that compressive strength, UPV and RDME of samples were decreased with increase in PA ratios. Test results revealed that HSC was still durable after 100, 200 and 300 cycles of freezing and thawing in accordance with ASTM C666. After 300 cycles, HSC showed a reduction in compressive strength between 6% and 21%, and reduction in RDME up to 16%. For 300 cycles, the porosity was increased up to 12% for HSC with PA. In this paper, feed-forward artificial neural networks (ANNs) techniques are used to model the relative change in compressive strength and relative change in UPV in cyclic thermal loading. Then genetic algorithms are applied in order to determine optimum mix proportions subjected to 300 thermal cycling.     

Synthesis,Characterization, and Thermoelectric Properties of Electrospun Boron-Doped Barium-Stabilized Bismuth-Cobalt Oxide Nanoceramics

In this study, the boron-doped barium-stabilized bismuth cobalt oxide thermoelectric nanocrystalline ceramic powders were produced by the polymeric precursor technique. The powders were characterized by X-ray diffraction, scanning electron microscopy, and the physical properties measurement system. The X-ray diffraction results showed that these patterns have mixture of two phases as face-centered cubic and body-centered cubic. Values of the crystallite size, the dislocation density, and the microstrain were calculated by the Scherrer equation. According to these values, the crystallite size decreased from 60 to 51 nm with the boron addition in the boron-undoped and boron-doped samples, respectively. The scanning electron microscope results showed that nanograins are rarely seen in the boron-undoped samples, but nanograins turn into needle-like and layered structures with boron addition. The diameters distribution of nanofibers was calculated. The average diameter of the boron-doped sample is smaller than the boron-undoped sample. The physical properties measurement system values showed that the electrical and thermal conductivity, the Seebeck coefficient, and the figure of merit increased with the temperature rise for both samples. The boron-doping effect increased the electrical and thermal conductivity, decreased the Seebeck coefficient, and decreased the figure of merit.     

Application of GC, GC-MSD, ICP-MS and Spectrophotometric Methods for the Determination of Chemical Composition and In Vitro Bioactivities of Chroogomphus rutilus: The Edible Mushroom Species

Chemical composition of Chroogomphus rutilus, the edible mushroom species, was analyzed by using gas chromatography (GC), gas chromatography mass spectrometry (GC-MSD) and inductively coupled plasma mass spectrometry (ICP-MS). The silylated extract affords 19 components. Xylitol (56.28 %), glucitol (11.08 %), fumaric acid (10.92 %) and mannitol (6.79 %) were identified as the major compounds. The methylated extract possessed 13 fatty acids, and linoleic acid (41.61 %) and oleic acid (35.87 %) were the majors. In addition, the mineral and the heavy metal contents were tested for nine minerals and 12 heavy metals by using ICP-MS. In addition, the extracts were evaluated for cholinesterase inhibitory effects against acetyl-cholinesterase and butyrylcholinesterase which are the chief enzymes of Alzheimer’s disease. The antioxidative effect of the extracts was also determined by using five complimentary assays. Moreover, the hexane extract (IC₅₀, 2.22?±?0.13 μg/ml) and the ethyl acetate extract (IC₅₀, 2.28?±?0.18 μg/ml) exhibited a good lipid peroxidation inhibitory activity while the methanol extract demonstrated good butyrylcholinesterase inhibitory activity (IC₅₀, 45.5?±?1.1 μg/ml). In addition, total phenol and flavonoid contents of the extracts were also determined as pyrocatechol and quercetin equivalents, respectively. Because of its high antioxidant activity, C. rutilus might protect people against lipid peroxidation and free radical damage when consumed. It can be also used in food industry as preservative agents or extension of the shelf-life of foods. Since methanol extract indicated remarkable inhibitory activity being close to that of galantamine, it may be also useful as moderate cholinesterase inhibitory agents, particularly against butyrylcholinesterase.     

Geometric design of slider-crank mechanisms for desirable slider positions and velocities

In problems requiring uniform cutting speeds uniform flow rates etc. slider-crank mechanisms provide economical solutions. Thus, the problem of designing slider-crank mechanisms for desirable slider positions and velocities is handled within a geometric framework in this paper. Here, the rotation of the crank has been related to the translation of the slider through a linear function. A unified methodology comprising the so-called Subdomain, Galerkin methods together with the classical collocation method is implemented to find the values of the parameters involved. The effectiveness of the methodology has been demonstrated on numerical examples. Since more than one solution results from the solution process, it is always possible to form multi-loop mechanisms. Moreover, designs with low velocity errors in the forward stroke exhibit similar feature in the backward stroke too.     

Effect of Graphitic Nanosheets on the Physical Properties of Cyclic Olefin Copolymer Composite Films

In this study, microstructural and physical properties of cyclic olefin copolymer composite films prepared by melt processing method and using of graphitic nanofillers, namely, graphite, graphite oxide, and reduced graphite oxide were investigated. Structural and physical properties of the chemically modified graphites and composite films were characterized by the Fourier transform infrared, X-ray diffractometer, scanning electron microscopy, dynamic mechanical analyzer, and thermogravimetric analyzer methods. It was found that the composite films including reduced graphite oxide exhibited exfoliated structure whereas graphite- and graphite oxide-based films showed intercalated structure. It was also obtained that all composite films showed superior gas barrier performance compared to the cyclic olefin copolymer.     

Neutron Cross Section and Emission Spectra Calculations of Na Nucleus

Flibe (Li₂BeF₄) and Flinabe (LiFNaFBeF₂) are molten salt which are used as a first wall and blanket in advanced power extraction. Since they have low vapor pressure at high temperature and don’t pollute plasma. Moreover, they are used as a coolant material due to their high thermal cycling capacity. There are lots of benefits of using liquid wall such as reducing cost, increasing the reactor power and extending the life time of first steel wall. Being in Flinabe (LiFNaFBeF₂) molten salt, ²³ Na is also considered as a coolant material in fast reactors. Therefore, the reaction including neutron and ²³ Na is getting important. In this study, the cross section calculations of neutron induced reactions for ²³ Na were performed. Using pre-equilibrium and equilibrium models, excitation functions of ²³ Na(n,p)²³ Ne, ²³ Na(n,d)²² Ne, ²³ Na(n,α)²⁰ F, ²³ Na(n,2n)²² Na reactions and ²³ Na(n,xα), ²³ Na(n,xn) emission spectrums were calculated. We calculated alpha emission spectrum obtained when ²³ Na nuclei projectiled with 14.1 MeV neutrons and also neutron emission spectrum emitted when ²³ Na nuclei was bombardment with 14.6 MeV neutrons.     

Thermosonication of peach juice: investigation of PPO and POD activities,physicochemical and bioactive compounds changes,and development of FT-IR–based chemometric models for the evaluation of quality

In this research, the effect of thermosonication on peach juice was investigated. Enzyme inactivation increased with increasing power, temperature, and time. Enzymes were completely inactivated by thermosonication at 60 °C that was lower than the complete inactivation temperature (70 °C) of thermal treatment. Generally, as pH decreased, titratable acidity and °Brix increased by increasing temperature for each thermosonication treatment. The color of peach juice was preserved, and it became lighter. The bioactive components were protected with thermosonication. Fourier transform infrared (FT-IR) spectroscopy with chemometrics was used to evaluate polyphenol oxidase and peroxidase activity and quality attributes during thermosonication treatment. Moreover, the treatment methods were differentiated using principal component analysis, and models that correlated enzyme activity, quality attributes, and bioactive compounds with infrared spectra were constructed using partial least-squares. FT-IR with chemometrics can be used as a reliable method in peach juice quality determination during thermosonication.     

Determination of optimum welding parameters in connecting high alloyed X53CrMnNiN219 and X45CrSi93 steels by friction welding

In this study, different welding parameters were applied to two different steels with high alloys and mechanical and metallographical investigations are performed. Thus, the optimum welding parameters were determined for these materials and working conditions. 12·30 diameter steel bars made up of 1·4871 (X53CrMnNiN219) and 1·4718 (X45CrSi93) steel were used as experimental material. The material loss increased with increase in friction and rotating pressure. No fracture at the welding region was observed and the highest fracture energy was identified in B5 group. Based on micro hardness investigation; the hardness profile reached its minimum value at the welding region.