Electrophoretic deposition of titanium nitride coatings

Electrophoretic deposition of the titanium nitride (TiN) coatings from suspensions prepared by dispersion of TiN particles in triethanolamine (TEA) containing butanol medium was studied. Effects of the TiN particles concentration (C_TiN) on the weight of the deposited coatings, triethanolamine concentration (C_TEA=0.25, 0.5, 0.75, and 1 mL/L) on the Zeta potential of the TiN particles, suspension electrical conductivity and pH, as well as effects of the deposition voltage (V_d=60, 90, and 120 V) and time (t_d =1, 2, and 3 minutes) on the microstructure and thickness of the deposited coatings were investigated. Variations in deposition current density, effective deposition voltage, electrical resistance, and deposited coating weight versus deposition time were recorded. The morphology of the as‐dried coatings was studied using Scanning Electron Microscope (SEM). The results indicated that by increasing the C_TiN the weight of deposits increases linearly up to 40 g/L. For suspensions containing C_TiN=40 g/L, the optimum C_TEA is obtained to be 0.5 mL/L leading to Zeta potential of 43.25 mV. Uniform and crack‐free as‐dried coatings obtained at V_d and t_d of 90 V and 2 minutes, respectively.     

Modification of electrospun poly(L-lactic acid)/polyethylenimine nanofibrous scaffolds for biomedical application

In this study, modification of poly(L-lactic acid) (PLLA) electrospun nanofibrous scaffolds blending with polyethylenimine (PEI) in different blend ratios was performed. The sample with 85:15 blend ratio revealed most promising results, and was selected for further modification with gelatin. It was found that the presence of PEI could enhanced porosity, mechanical properties, surface/bulk hydrophilicity and also gelatin grafting density about five times with positive effect on cell behavior. The results indicated that the limitations of PLLA electrospun nanofibers for potential application as a functional tissue engineering scaffold (i.e., poor cell adhesion and necrosis of host tissues as a result of providing acidic environment while degradation) could be overcome through blending with PEI and grafting with gelatin.     

Towards Green Capacity in Massive Mimo Based 4G-LTE a Cell Using Beam-Forming Vector Based Sectored Relay Planning

Wireless Personal Communications - In this information age, high data rates and good reliability features are becoming the dominant factors for a successful deployment of commercial networks....     

Gas-liquid flow mass transfer in a T-shape microreactor stimulated with 1.7 MHz ultrasound waves

This paper describes the application of ultrasound waves on hydrodynamics and mass transfer characteristics in the gas-liquid flow in a T-shape microreactor with a diameter of 800 μm.A 1.7 MHz piezoelectric transducer (PZT) was employed to induce the vibration in this microreactor.Liquid side volumetric mass transfer coefficients were measured by physical and chemical methods of CO2 absorption into water and NaOH solution.The approach of absorption of CO2 into a 1 mol· L-1 NaOH solution was used for analysis of interfacial areas.With the help of a photography system,the fluid flow patterns inside the microreactor were analyzed.The effects of superficial liquid velocity,initial concentration of NaOH,superficial CO2 gas velocity and length of microreactor on the mass transfer rate were investigated.The comparison between sonicated and plain microreactors (microreactor with and without ultrasound) shows that the ultrasound wave irradiation has a significant effect on kLa and interfacial area at various operational conditions.For the microreactor length of 12 cm,ultrasound waves improved kLa and interfacial area about 21％ and 22％,respectively.From this study,it can be concluded that ultrasound wave irradiation in microreactor has a great effect on the mass transfer rate.This study suggests a new enhancement technique to establish high interfacial area and kLa in microreactors.     

Buckling and dynamic instability analysis of stiffened shell panels

The static and dynamic instability characteristics of stiffened shell panels subjected to uniform in-plane harmonic edge loading are investigated in this paper. The eight-noded isoparametric degenerated shell element and a compatible three-noded curved beam element are used to model the shell panels and the stiffeners, respectively. As the usual formulation of degenerated beam element is found to overestimate the torsional rigidity, an attempt has been made to reformulate it in an efficient manner. Moreover, the new formulation for the beam element requires five degrees of freedom per node as that of shell element. The method of Hill's infinite determinant is applied to analyze the dynamic instability regions. Numerical results are presented through convergence and comparison with the published results from the literature. The effect of various parameters like shell geometry, stiffening scheme, static and dynamic load factors, stiffener size and position, and boundary conditions are considered in buckling and dynamic instability analysis of stiffened panels subjected to uniform in-plane harmonic loads along the boundaries.     

Physiochemical characterizations of hydroxyapatite extracted from bovine bones by three different methods: Extraction of biologically desirable HAp

In the present study, subcritical water and alkaline hydrolysis methods are proposed methodologies for extraction of natural hydroxyapatite bioceramic from bovine bone. In these processes, the bovine bones powder were treated by high pressure water at 250 °C for 1 h and 25% (wt) sodium hydroxide at 250 °C for 5 h, respectively. Also the conventional calcination methodology has been utilized as well (T = 850 °C for 1 h). The obtained apatites from the three treatment processes have been characterized by powder X-ray diffraction analysis (XRD), Fourier transform infrared spectroscopy (FT IR), transmission electron microscopy (TEM), thermal gravimetric analysis (TGA), electron scanning microscopy (SEM), energy dispersive X-ray analysis (EDX) and field emission scanning electron microscopy (FE SEM). FT IR and XRD results affirmed that both the proposed methods and the traditional one can eliminate the collagen and other organic materials present in the bovine bones. The physiochemical characterizations for the obtained apatites have proved that the subcritical water and the alkaline hydrolysis relatively preserve the carbonate content present in the biological apatite, so they yield carbonated hydroxyapatite which is medically preferable. While, the thermal process produces almost hydroxyapatite carbonate-free.     

A new design approach for dual‐band patch antenna serving Ku/K band satellite communications

A printed planar antenna with simple and intelligent geometrical structure has been proposed for Ku/K band satellite communication systems. The radiating patch of the antenna is formed by cutting rectangular slots and extending the radiating element to some extent. The final design of the antenna with optimized parameters is fabricated on ceramic–polytetrafluoroethylene substrate materials of dielectric constant ε_r = 10.2. The antenna is excited through a microstrip feed line and has reduced ground plane that covers only the non‐radiating portion of the antenna. The reduced complexity of the antenna is easy to fabricate and has overall dimension of 40 × 35 × 1.905 mm³. The results from experimental analysis show that the proposed antenna can guarantee a wide bandwidth of 12.0 to 16.4 GHz at lower band, and the upper band covers the frequency in the range of 17.53 to 19.5 GHz. The antenna has achieved appreciable gain in the range of 3.14 to 4.68 dBi for lower band and 2.03 to 3.65 dBi for upper band. The proposed antenna has offered almost symmetrical and directional radiation pattern that is essentially suitable for serving Ku/K band satellite applications. Copyright © 2015 John Wiley & Sons, Ltd.     

Effects of residence time and heating rate on gasification of petroleum residue

Gasification of petroleum residue has been considered as the potential technology due to the advantages of converting the liquid fuels into syngas using partial oxidation. In this paper, we developed a one-dimensional kinetic model to simulate the effects of residence time and heating rate on the gasification characteristics. Results showed that gasification under higher heating rate improves the hydrogen yield and carbon conversion efficiency. It was also found that the residence time plays a major role in the process; higher residence time improves the hydrogen yield and gasification efficiency. The model was validated against the reported data and found to be in good agreement.     

Nonconvulsive status epilepticus: high incidence in dialysis-dependent patients

Nonconvulsive status epilepticus is defined as a mental status change from baseline of at least a 30-min duration associated with constant or near-continuous ictal discharges on an electroencephalogram (EEG). Nonconvulsive status epilepticus is an often-overlooked diagnosis as a cause of acute confusional state. There are few case reports in dialysis patients. We are reporting 5 patients on chronic dialysis treatment who presented with an acute confusional state. Nonconvulsive status epilepticus was diagnosed by EEG and response to intravenous benzodiazepines. We recommend early EEG to be considered in the evaluation of dialysis patients with an acute confusional state.