Design of efficient power amplifier for low power transmitters

This paper presents a fully integrated, low transmit-power and high-efficiency 2.4 GHz class-E power amplifier (PA) in TSMC 0.18 μm CMOS process for low-power transmitters such as wireless sensor networks (WSN). In this paper, a new output load has been proposed. Also, analytical design equations have been included to design an efficient low power circuit. This PA, employs the pad capacitance and bond-wire inductance of the output node, for satisfying class-E zero-voltage switching (ZVS) condition and matching the antenna’s 50 Ω resistance. By using bond-wire inductance instead of inductor in the output filter, smaller chip size and higher efficiency has been achieved compared to other works for low transmit-power applications. Also, the effectiveness of bulk-drive technique on faster switching and increasing efficiency have been evaluated. It has been proved that this technique leads to increase the efficiency of switching PAs. This PA delivers a range of output power from 2.7 to 7.2 dBm with a supply voltage range from 500 to 850 mV while achieving overall power efficiency range of 57.3–60.7%.     

Selective Removal of Carbon Dioxide from Wet CO2/H2 Mixtures via Facilitated Transport Membranes containing Amine Blends as Carriers

The selective separation of carbon dioxide (CO₂) from a wet gaseous mixture of CO₂/H₂ through facilitated transport membranes containing immobilized aqueous solutions of monoethanolamine (MEA), diethanolamine (DEA), ethylenediamine (EDA) and monoprotonated ethylenediamine (EDAH⁺) and their blends was experimentally investigated. The effect of CO₂ partial pressure, amine concentration, feed side pressure and amine species on the CO₂ and H₂ permeances were studied. The CO₂ permeability through amine solution membranes decreased with increasing CO₂ feed partial pressure but the H₂ permeance was almost independent of the H₂ partial pressure. A comparison of experimental results showed that single or blended amines with low viscosity and a moderate equilibrium constant, i.e., large forward and reverse reaction rate of CO₂‐amine, are suitable for effective separation of CO₂. The permeability of CO₂ generally increased with an increase in amine concentration, although this increase may be compromised by the salting out effect and decrease in diffusivities of species. The results obtained indicated that CO₂ permeance across a variety of amines are in the order of DEA (2 M) > MD (2 M) > MD (1 M) > MEA (2 M) > MEA (4 M) > MD (4 M) > DEA (1 M) > DEA (4 M) > MEA (1 M) for various concentrations of MEA + DEA blend and are in the order of EDAH⁺ (2 M) > DEA (2 M) > MH (2 M) > DH (2 M) > ED (2 M) > EDA (2 M) > MEA (2 M) for various blends of amine.     

Preparation of novel 2-(2-oxo-2H-chromen-4-yl)-3- arylthiazolidin-4-one derivatives using an efficient ionic liquid catalyst

An eco-friendly procedure for synthesis of 2-(2-oxo-2H-chromen-4-yl)-3-arylthiazolidin-4-one derivatives by three-component reaction of 2-oxo-2H-chromene-4-carbaldehydes, aromatic amines and thioglycolic acid, with tetramethylbutane-1,4-diammonium acetate as a low-cost ionic liquid catalyst under reflux condition is described. The use of an ionic liquid as a catalyst has the advantages of high yields, short reaction time and environmentally friendly reaction media.     

Protein Kinases and Parkinson’s Disease

Currently, the lack of new drug candidates for the treatment of major neurological disorders such as Parkinson’s disease has intensified the search for drugs that can be repurposed or repositioned for such treatment. Typically, the search focuses on drugs that have been approved and are used clinically for other indications. Kinase inhibitors represent a family of popular molecules for the treatment and prevention of various cancers, and have emerged as strong candidates for such repurposing because numerous serine/threonine and tyrosine kinases have been implicated in the pathobiology of Parkinson’s disease. This review focuses on various kinase-dependent pathways associated with the expression of Parkinson’s disease pathology, and evaluates how inhibitors of these pathways might play a major role as effective therapeutic molecules.     

New chatter-free sliding mode synchronization of steer-by-wire systems under chaotic conditions

Vehicle safety issues and its systems dependence on electronics are rapidly increasing. In intelligent vehicles, rigid components are replaced with controlled x-by-wire systems including configurable electronic elements. In the paper, through complete modeling of Steer-by-wire (SBW) nonlinear dynamics, the chaotic motion of the system is elucidated by a new yaw stability control method. The designed chatter free Sliding mode controller (SMC) is used to synchronize chaotic motion of the SBW system. Following stability and robustness analysis, computer simulations show that the proposed control system is quite significant for nonlinear systems like the SBW system. Besides, the robustness of the SMC against exogenous disturbance protects vehicle from undesired slide and spin motions.

     

Static and dynamic corrosion behavior of SnO2-doped AZS slip cast refractory in SLS glass

The corrosion behavior of a tin IV oxide-doped AZS-refractory, subject to static and dynamic corrosion testing at 1370˚C in soda-lime-silica glass, was studied considering the effect of the microstructural features on corrosion. The refractory was synthesized by slip cast methods through reaction sintering of alumina and zircon raw materials using SnO₂ as a sintering agent. SnO₂ had a considerable influence in the enhanced alumina/zircon reaction sintering and the subsequently evolved microstructures of an interlocked Zr_(1-x)Sn_(x)O₂ solid solution reinforced alumina-mullite composite. The process kinetics of the refractory corrosion followed reasonably well the predicted dependence on the square root of angular velocity under forced convection corrosion. Glass chemical corrosion and erosion of the refractory, under static and dynamic glass conditions, respectively, revealed the Zr_(1-x)Sn_(x)O₂ solid solution-rich mullite matrix as providing the most corrosion resistance and glass compatibility.     

CFD and artificial neural network modeling of two-phase flow pressure drop

A large number of experiments in a 2 cm diameter and 6 m length tube were carried out in order to study the two-phase flow regimes and pressure drops in it. The two-phase flow in the experimental tube was modeled using commercial CFD code, Fluent 6.2. An Artificial Neural Network (ANN) with three inputs including gas and liquid velocities and tube slope was designed and trained to predict average pressure drop across the tube. The comparison between CFD and ANN predictions of pressure drops with experimental measurements shows that the CFD results are more accurate than the ANN evaluations for new conditions.     

Effect of process variables on product yield distribution in thermal catalytic cracking of naphtha to light olefins over Fe/HZSM-5

The effect of temperature, WHSV and Fe loading over HZSM-5 catalyst in thermal-catalytic cracking (TCC) of naphtha for the production of light olefins has been studied. The response surface defined by three most significant parameters is obtained from Box-Behnken design method and the optimal parameter set is found. The results show that ethylene increases with temperature, while propylene shows an optimum at 650 °C. Moderate WHSV is favorable for maximum production of light olefins. Addition of Fe to HZSM-5 has a favorable effect on the production of light olefins up to 6% of loading. Excess amount of loading decreases the conversion of naphtha, which leads to a drop in light olefin yields. The yield of light olefins (ethylene and propylene) at 670 °C, 44 hr⁻¹ and 6 wt% Fe has been increased to 5.43 wt% compared to the unmodified HZSM-5 and reaches to 42.47 wt%.