Post-buckling behavior of carbon fiber epoxy composite plates

In this study, the pre-buckling and post-buckling behaviors of layered composite plates which were made of woven carbon fiber fabric with a circular hole in the middle were investigated experimentally and numerically. Firstly, load-displacement graphs of composite plates with different hole diameters were experimentally obtained under compressive load. Then the numerical load-displacement graphs of the plates were found with the ANSYS package program which used the finite element method. As a result, after linear buckling experimental and numerical results were found to be compatible with each other. In addition, damage behavior of plates after buckling with the aid of Tsai-Wu damage criterion was obtained similar to experimental results. The increase in hole diameter did not change the load-displacement behavior characteristics of the plates after buckling. However, it has reduced maximum damage load and maximum failure displacement. The stress at the perimeter of the hole increased significantly with the increase of the vertical displacement with immediately after the buckling but later was not significantly affected by this increase.

     

Investigation of flow properties in natural streams using the entropy concept

This paper examines the discharge and velocity distributions in natural open channel flows using the entropy theory. Flow measurements were carried out at four different cross‐sections in central Turkey. The mean and maximum velocities at these stations exhibited a linear distribution and the entropy parameter was calculated to be M=1.31. Using this value, discharges for all flow conditions were calculated as a function of the measured maximum velocities (u_max). It was observed that the u_max/H and z_max/H ratios remained relatively constant when 0.2≤y/T≤0.8, especially for the wider channels. Using these constant values for each station, u_max and z_max could be determined solely as a function of the water depth H. Although the calculated velocities were higher than those measured at some verticals, the entropy‐based approach presents an attractive alternative to the traditional flow‐measurement techniques for the determination of flow properties because of its simplicity and quick application.     

Controlled synthesis of transition metal/conducting polymer nanocomposites

A novel displacement reaction has been observed to occur between conducting polymers (CP) and metal salts which can be used to fabricate nanostructured CP-metal composites in a one-pot manner. Vanadium pentoxide (V (2)O(5)) nanofiber is used during the synthesis as the reactive seeds to induce the nanofibril CP-metal network formation. The CP-metal nanocomposites exhibit excellent sensory properties for hydrogen peroxide (H(2)O(2)) detection, where both high sensitivity and a low detection limit can be obtained. The sensory performance of the CP-metal composite can be further enhanced by a facile microwave treatment. It is believed that the CP-metal nanofibril network can be converted to a carbon-metal network by a microwave-induced carbonization process and result in the sensory enhancement.     

Synthesis of Cherry Stalk Extract Based Organic@Inorganic Hybrid Nanoflowers as a Novel Fenton Reagent: Evaluation of Their Antioxidant,Catalytic, and Antimicrobial Activities

First time in this study, organic@inorganic hybrid copper nanoflowers (Cu NFs) were synthesized by using cherry stem extract as an organic component and Cu²⁺ ion as an inorganic component. For this purpose, cherry stalk extracts were obtained by using ethanol and water solvents. Cu NFs were synthesized in different amounts of extract (100–1000 µl) and under various pH (7.4–9) conditions. The morphologies of the synthesized Cu NFs were evaluated by field emission scanning electron microscope (FE-SEM). The functional groups in the cherry stem extract, which play an active role for the synthesis process, and the crystal structure of NFs were investigated by Fourier transform ?nfrared spectroscopy and X-ray diffraction techniques, respectively. It has been determined by the FE-SEM analysis that ethanol and water based cherry stem extracts are suitable for Cu NFs synthesis in a wide range of pH (7.4–9). This data is crucial for overcoming important limitations for NF synthesis, such as narrow-range medium pH. The catalytic, antioxidant, and antimicrobial activities of Cu NFs were evaluated. It was revealed that Cu NFs have catalytic, antioxidant, and antimicrobial activities. It is recommended that, cherry stem extract and different inorganic components are functional to synthesize numerous NFs and to evaluate the adequacy of use in biomedical fields.

     

Microwave Dehydration of Borax: Characterization,Dehydration Kinetics,and Modelling

Glass Physics and Chemistry - In the present study, borax (Na2B4O7·10H2O) was dehydrated using microwave radiation and the dehydration rate curves were calculated. The kinetic parameters and...     

One step densification of SDC—Na2CO3 nano-composite electrolytes for SOFC applications by cold sintering process

Sm_0.2Ce_0.8O_1.9- 30% Na₂CO₃ (Sm doped ceria (SDC)-30N) nano-composite electrolytes were densified in a single step via cold sintering process (CSP). At 200°C and 450 MPa of uniaxial pressure, samples up to 97% of their theoretical density could be obtained. The effect of processing parameters, such as temperature, uniaxial pressure, processing duration, and moisture content, on the densification of the nano-composite electrolytes was investigated. The thermal, microstructural, and electrical properties of nano-composites were investigated by differential scanning calorimetry, X-ray diffractometer, scanning electron microscope, and EIS analysis. SDC crystallite sizes were found to be around 25 nm, barely coarsened after CSP by which the true nano nature of the nano-composite could be preserved. Because, by conventional processing high density values could not be attained and high processing temperatures in excess of 600°C had to be used, promoting particle coarsening. The highest total electrical conductivity was found to be 2.2 × 10⁻² S cm⁻¹ at 600°C, with an activation energy of 0.83 eV for SDC-30N nano-composites. The present investigation revealed that the implementation of cold sintering technique resulted in significant enhancements in the densification of nano-composite electrolytes, thereby rendering them suitable for efficient utilization in SOFC applications, as compared to the conventional production methods.