Hardness and electrical resistivity of Al–13 wt % Mg<Subscript>2</Subscript>Si pseudoeutectic alloy

In the present work, effect of growth rates on microhardness, electrical properties and microstructure for directionally solidified Al–13 wt % Mg₂Si pseudoeutectic alloy at a constant temperature gradient were studied. Directional solidification process were carried out with five different growth rates (V = 8.33–175.0 μm/s) at a constant temperature gradient (G = 6.68 K/mm) by using a Bridgman type directional solidification furnace. Microstructure of directionally solidified Al–13 wt % Mg₂Si pseudoeutectic alloy was observed as Mg₂Si coral-like structure phase dispersed into primary α-Al phase matrix. The electrical resistivity for Al–13 wt % Mg₂Si pseudoeutectic alloy, were measured by the d.c. four-point probe method. The dependency ofmicrohardness and electrical resistivity on growth rates were obtained as HV = 135.7 (V)^0.09 and ρ = 17.30 × 10^?8(V)^0.08, respectively for Al–Mg₂Si pseudoeutectic alloy. The results obtained in present work were compared with the previous similar experimental results.     

SH3-Binding Glutamic Acid Rich-Deficiency Augments Apoptosis in Neonatal Rat Cardiomyocytes

Congenital heart disease (CHD) is one of the most common birth defects in humans, present in around 40% of newborns with Down’s syndrome (DS). The SH3 domain-binding glutamic acid-rich (SH3BGR) gene, which maps to the DS region, belongs to a gene family encoding a cluster of small thioredoxin-like proteins sharing SH3 domains. Although its expression is confined to the cardiac and skeletal muscle, the physiological role of SH3BGR in the heart is poorly understood. Interestingly, we observed a significant upregulation of SH3BGR in failing hearts of mice and human patients with hypertrophic cardiomyopathy. Along these lines, the overexpression of SH3BGR exhibited a significant increase in the expression of hypertrophic markers (Nppa and Nppb) and increased cell surface area in neonatal rat ventricular cardiomyocytes (NRVCMs), whereas its knockdown attenuated cellular hypertrophy. Mechanistically, using serum response factor (SRF) response element-driven luciferase assays in the presence or the absence of RhoA or its inhibitor, we found that the pro-hypertrophic effects of SH3BGR are mediated via the RhoA–SRF axis. Furthermore, SH3BGR knockdown resulted in the induction of apoptosis and reduced cell viability in NRVCMs via apoptotic Hippo–YAP signaling. Taking these results together, we here show that SH3BGR is vital for maintaining cytoskeletal integrity and cellular viability in NRVCMs through its modulation of the SRF/YAP signaling pathways.     

Life cycle evaluation of hydrogen and other potential fuels for aircrafts

In the present study, hydrogen and some other alternative fuels (such as ammonia, methanol, ethanol, liquefied natural gas) are considered for aviation applications under a comprehensive life cycle assessment study and are evaluated comparatively with the conventional kerosene based jet fuel for various impact categories. Therefore, this study is performed with a well-to-wake approach to evaluate the overall life cycle of an aircraft running on these conventional and alternative fuels. Both conventional and renewable fuel routes are considered for the production of ammonia and hydrogen fuels. Although there are modifications required to fulfill the aviation fuel specifications for such alternative fuels, the long term viability and environmental sustainability make them attractive solutions for the future of aviation industry. This study uses a life cycle assessment of an average aircraft utilizing various alternative aviation fuels to determine the relative environmental impact of each life cycle phase. The life cycle phases included in the analyses are as follows: (i) production, operation and maintenance of the aircraft, (ii) construction, maintenance and disposal of the airport, (iii) production, transportation and utilization of the aviation fuel in the aircraft. The results show that hydrogen and liquefied natural gas represent more environmentally benign alternatives although fuel costs are higher compared to ammonia, jet fuel and methanol. The total GHG emissions from hydropower based ammonia and hydrogen are calculated to be about 0.24 kg CO₂ eq. per traveled tonne-km and 0.03 kg CO₂ eq. per traveled tonne-km, respectively. Renewable based ammonia and hydrogen fueled aircrafts can further decrease the overall environmental impact in many categories allowing a brighter future for aviation industry.     

Performance prediction of PEM fuel cell with wavy serpentine flow channel by using artificial neural network

Effects of serpentine flow channel having sinusoidal wave at the rib surface on performance of PEMFC having 25 cm² active area are investigated at different flow rates, three different amplitudes changing from 0.25 mm to 0.75 mm and three different cell operation temperatures. A proton exchange membrane fuel cell (PEMFC) is modeled for the prediction of the output current by using artificial neural network (ANN) that is utilized the aforementioned experimental parameters. Effect of hydrogen and air flow rate, the fuel cell temperature, amplitude of channel is tested. The results indicated that model C1 having lowest amplitude is enhanced maximum power output up to 20.15% as compared to indicated conventional serpentine channel (model C4) for 0.7 SLPM H₂ and 1.5 SLPM air and also model C1 has better performance than C2, C3 and C4 models. The maximum power output is augmented with increasing the cell temperature due to raising the fuel and oxidant diffusion ratio. Cell temperature, amplitude, H₂ and air flow rate and input voltage is used as input variables in train and test of the developing ANN model. MAPE of training and testing is determined as 2.89 and 2.059, respectively. Prediction results of developed ANN model including two hidden layer shows similar trend with experimental results. Developed ANN model can be used to both decrease the number of required experiments and find the optimum operation condition within the range of input parameters.     

Synthesis and Characterization of New Metal–Organic Frameworks Based on Tetracyanoplatinate(II) and N,N′-bis(2-hydroxyethyl)ethylenediamine: Single Crystal Structures of ZnII and CdII Complexes Along with Magnetic Properties of NiII and CuII Complexes

Characterization and synthesis of novel cyano bridged coordination compounds [Ni(bishydeten)Pt(CN)₄] (1), [Cu(bishydeten)Pt(CN)₄] (2), [Zn(bishydeten)Pt(CN)₄] (3), [Cd(bishydeten)Pt(CN)₄] (4) [bishydeten = N,N′-bis(2-hydroxyethyl)ethylenediamine (C₆H₁₆N₂O₂)] were reported herein. The IR spectra of these coordination compounds verified the formation of aforementioned complexes. The ground state of the paramagnetic electron in the Cu^II located in tetragonal distorted octahedral sites (D _4h ) was found to be d_x2−y2 for complex 2. As for complex 1, an EPR signal was not observed because of diamagnetic property of the Pt^II and momentary relaxation times of the Ni^II. All complexes followed identical decomposition mechanism in thermal analysis and thermal stabilities of complexes changed in the order of 1 > 4 > 3 > 2. Both 3 and 4 exhibit polymeric structure according to X-ray single structure analysis. While bishydeten coordinated with three donor atoms (N,N′, and O) in complex 3, it acts as a bidentate ligand (N, and N′) in complex 4. Magnetic properties of complexes 1–2 at 15–300 K temperature range were determined as antiferromagnetic with Weiss constants = −2.619 and −0.847 K respectively.     

Two Novel Bimetallic Cyano-Bridged Coordination Polymers Containing the 2,2′-(Ethylenedioxy)bis (Ethylamine): Syntheses,Structural, Thermal and Magnetic Properties

Two new cyano bridged bimetallic polymeric complexes, [Ni(edbea)Ni(CN)₄]·1/2H₂O (1) and [Cu(μ-edbea)(μ-CN)₂ Ni(CN)₂]·H₂O (2) [edbea = 2,2′-(ethylenedioxy)bis(ethylamine)] have been synthesized by adding metal chloride (M = Ni^II and Cu^II), and edbea into [Ni(CN)₄]²⁻ in water–ethanol solution and then characterized by elemental analysis, infrared (IR) and electron paramagnetic resonance (EPR) (for only complex 2) spectra, variable temperature magnetic measurement, and thermal gravimetric analysis. The X-ray diffraction crystal structure of complex 2 shows a 2D polymeric chain –edbea(N5,O1)–Cu1–N1C1–Ni(CN)2–C4N6–Cu1–(N6,O2) edbea– in which the Cu^II centers are linked by two cyano and one edbea. The powder EPR spectrum of the complex 2 has shown that Cu^II ions are located in rhombically distorted octahedral sites. The magnetic properties of the coordination polymers have been studied in temperature range of 15–300 K. The magnetic behaviors investigation of complexes 1 and 2 indicated the presence of a very weak antiferromagnetic interaction.     

The effect of cutting parameters and cutting tools on machining performance of carbon graphite material

Abstract

The present study focuses on the effects of cutting speed, feed rate and cutting tool material on the machining performance of carbon graphite material. Polycrystalline Diamond (PCD) cutting tools are used in machining experiments and its performance is compared with the tungsten carbide (WC) and Cubic Boron Nitride (CBN) tools. Machining performance criteria such as flank and nose wear and resulting surface topography and roughness of machined parts were studied. This study illustrates that feed rate and cutting tool material play a dominant role in the progressive wear of the cutting tool. The highest feed rate and cutting speed profoundly reduce the tool wear progression. The surface roughness and topography of specimens are remarkably influenced from the tool wear. Major differences are found in the wear mechanisms of PCD and WC and CBN cutting tools.     

Thermally curable benzoxazine-modified vegetable oil as a coating material

In this article, a new synthetic approach for the modification of partial glycerides (PG) obtained from sunflower oil with thermally curable benzoxazine units and its potential use as a coating material are described. For this purpose, hydroxyl-containing benzoxazine monomer was first prepared by conventional ring-forming reaction of phenol with paraformaldehyde in the presence of 6-amino-1-hexanol. The subsequent urethane reaction between PG and the benzoxazine monomer using toluene diisocyanate yields corresponding modified oil. The structures of the intermediates, and the modified triglycerides are confirmed by FTIR and ¹H NMR spectral analysis. Thermally activated curing behaviors of the precursor and the modified oil in the absence of any catalyst were studied by differential scanning calorimetry. Thermal and film properties of the cured products were also investigated.     

Diffraction of homogeneous and inhomogeneous plane waves by a planar junction between perfectly conducting and impedance half-planes

The problem of diffraction of homogeneous and inhomogeneous plane waves at the discontinuity formed by perfectly conducting and impedance half-planes is examined by the method of modified theory of physical optics (MTPO). The MTPO integral of the reflected scattered waves by the perfectly conducting half-plane is reconstructed in order to include the effect of the diffracted wave coming from the edge of the impedance half-plane. The integrals are evaluated by a uniform asymptotic method. The results are plotted numerically and compared with the literature.     

Electrochemically grown ZnO nanorods for hybrid solar cell applications

A hybrid solar cell is designed and proposed as a feasible and reasonable alternative, according to acquired efficiency with the employment of zinc oxide (ZnO) nanorods and ZnO thin films at the same time. Both of these ZnO structures were grown electrochemically and poly(3-hexylthiophene):phenyl-C61-butyric acid methyl ester; (P3HT:PCBM) was used as an active polymer blend, which was found to be compatible to prepared indium-tin-oxide (ITO) substrate base. This ITO base was introduced with mentioned ZnO structure in such a way that, the most efficient configuration was optimized to be ITO/ZnO film/ZnO nanorod/P3HT: PCBM/Ag. Efficiency of this optimized device is found to be 2.44%. All ZnO works were carried out electrochemically, that is indeed for the first time and at relatively lower temperatures.