Specialized Study on Morphological Features of Tungsten Carbide Thin Film Synthesis by HFCVD

Tungsten carbide (WC) thin film was fabricated by the hot filament chemical vapor deposition method for 10 min as time deposition at the substrate temperature of 400 and 600 °C, under vacuum in the atmospheres of 95 % argon and 5 % methane gas mixture. In this work, the substrate temperature dependence of the WC properties was discussed. X-ray diffraction was used to identify the growth of structural properties of WC thin film on the Si (100) substrate. In order to investigate the morphological features of samples; raman scattering, field emission scanning electron microscopy and cross-sectional scanning electron microscopy (cross-sectional SEM) were used. Atomic force microscopy, mountains map premium (64-bit version) and Gwyddion software analysis were also used for further investigation. In this study, the analysis of the Minkowski functionals, the motifs, the depth histograms, the statistical parameters, the texture direction and the peak count histograms of the nanostructure surface of samples were implemented. According to the analyses, the WC films had a good crystal quality without any deformity and a low residual stress. The results of this study can accurately be used for a better comprehension of the WC thin film structures and characteristics.     

Castor oil transesterification reaction: A kinetic study and optimization of parameters

In this paper, parameters affecting castor oil transesterification reaction were investigated. Applying four basic catalysts including NaOCH₃, NaOH, KOCH₃ and KOH the best one with maximum biodiesel yield was identified. Using Taguchi method consisting four parameters and three levels, the best experimental conditions were determined. Reaction temperature (25, 65 and 80 °C), mixing intensity (250, 400 and 600 rpm), alcohol/oil ratio (4:1, 6:1 and 8:1) and catalyst concentration (0.25, 0.35 and 0.5%) were selected as experimental parameters. It was concluded that reaction temperature and mixing intensity can be optimized. Using the optimum results, we proposed a kinetic model which resulted in establishing an equation for the beginning rate of transesterification reaction. Furthermore, applying ASTM D 976 correlation, minimum cetane number of produced biodiesel was determined as 37.1.     

An efficient one-pot synthesis of tetrahydrothiazolo[3,2-a]quinolin-6-one derivatives

The cysteamine hydrochloride as a practical precursor of 2-(nitromethylene)thiazolidine in the one-pot synthesis of thiazoloquinoline derivatives from aromatic aldehydes and dimedone is described. This protocol involved Michael reaction, imine–enamine tautomerization, and cyclization sequence. Simple operation under mild conditions, easy accessibility of reactants, short reaction times, simple workup procedure, high atom economy, and the use of ethanol/water as a green medium make this approach attractive for the synthesis of variety of such derivatives.     

Blends of photovoltaic-grade ethylene–vinylacetate copolymers and low-density ethylene–octene copolymers,their morphology and their thermal,mechanical, and rheological properties

Blends of photovoltaic-grade ethylene–vinyl acetate copolymer (EVA), defined by high VA-content and low crystallinity, and low-density ethylene–octene copolymer (EO) have been investigated with regard to their processing, thermal and mechanical properties as well as their morphology. It was found that the amount of EO in the blend has a strong influence on the shear thinning behavior, melt viscosity and therefore the required extrusion temperature and resulting ability to incorporate temperature-sensitive additives like a peroxidic crosslinking agent. A phase separated morphology was found for all blend compositions, though partial miscibility leading to co-crystallization was observed for EVA rich blends. EO rich blends show lower glass transition and higher melting point compared to neat EVA and exhibit higher elastic modulus at elevated temperatures as well as greater elongation at break during tensile testing while the light transmission is diminished. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47714.     

Free vibration of magneto-electro-elastic nanobeams based on modified couple stress theory in thermal environment

In this paper, the size-dependent free vibration of magneto-electro-elastic (MEE) nanobeams in thermal environment is investigated. Size effects are taken into account using the modified couple stress theory, which is capable of accounting for higher-order electromechanical coupling, and the equations are developed on the basis of Euler–Bernoulli beam model and using von Karman nonlinear strain. The vibration of hinged–hinged nanobeams is investigated by way of example. Effects of various parameters such as temperature, thickness, and length on natural frequencies are demonstrated, and it is indicated that increased length and decreased thickness lead to decreased nanobeam natural frequencies.     

Solvent-free synthesis of Cu-Cu2O nanocomposites via green thermal decomposition route using novel precursor and investigation of its photocatalytic activity

In the present study, Cu-Cu₂O binary nanocomposites were successfully synthesized through a one-pot, cost-effective and green thermal decomposition route using PMP-Cu(II), extracted from pomegranate marc peels (PMP) by Cu(II), as a novel starting reagent for the first time. The morphology, crystalline structure, and composition of as-prepared Cu-Cu₂O nanocomposites were extensively characterized by SEM, XRD, EDS and HRTEM. Effect of reaction parameters such as time, temperature and precursor type on product composition and morphology was evaluated. Moreover, methylene blue (MB) was used as a model of organic dye pollutant and photodegradation experiments were conducted by UV-vis spectrophotometry. The as-synthesized Cu-Cu₂O binary nanocomposites demonstrated their potential as an excellent photocatalyst for degradation of MB under visible-light irradiation and Cu-Cu₂O photocatalyst with higher content of Cu₂O (prepared in air) exhibits the highest photocatalytic efficiency (～99% degradation of MB in <150 min).     

The rich photonic world of plasmonic nanoparticle arrays

Metal nanoparticle arrays that support surface lattice resonances have emerged as an exciting platform for manipulating light–matter interactions at the nanoscale and enabling a diverse range of applications. Their recent prominence can be attributed to a combination of desirable photonic and plasmonic attributes: high electromagnetic field enhancements extended over large volumes with long-lived lifetimes. This Review will describe the design rules for achieving high-quality optical responses from metal nanoparticle arrays, nanofabrication advances that have enabled their production, and the theory that inspired their experimental realization. Rich fundamental insights will focus on weak and strong coupling with molecular excitons, as well as semiconductor excitons and the lattice resonances. Applications related to nanoscale lasing, solid-state lighting, and optical devices will be discussed. Finally, prospects and future open questions will be described.     

Robust control of speed and temperature in a power plant gas turbine

In this paper, an H(∞) robust controller has been designed for an identified model of MONTAZER GHAEM power plant gas turbine (GE9001E). In design phase, a linear model (ARX model) which is obtained using real data has been applied. Since the turbine has been used in a combined cycle power plant, its speed and also the exhaust gas temperature should be adjusted simultaneously by controlling fuel signals and compressor inlet guide vane (IGV) position. Considering the limitations on the system inputs, the aim of the control is to maintain the turbine speed and the exhaust gas temperature within desired interval under uncertainties and load demand disturbances. Simulation results of applying the proposed robust controller on the nonlinear model of the system (NARX model), fairly fulfilled the predefined aims. Simulations also show the improvement in the performance compared to MPC and PID controllers for the same conditions.     

A 0.8 μm BiCMOS Gate Driver for IGBT Power Switch

This paper discusses the design and implementation of a monolithic gate driver for an Insulated Gate Bipolar Transistor (IGBT). The objective is to implement a high voltage (25 V) monolithic gate driver with a novel protection circuit in a conventional low-voltage (5 V) high-density (0.8 m) BiCMOS process. Extended drain MOS-FETs are used to implement the high-voltage capability in this design.