Dual‐polarized high gain resonant cavity antenna for radio frequency energy harvesting

A Fabry pérot antenna with a multilayer superstrate having nonuniform unit cells has been investigated as a receiving antenna for radio frequency (RF) energy harvesting applications. Here, the primary radiator is selected as a dual‐polarized aperture coupled microstrip antenna with a double‐layer superstrate. This antenna excites orthogonal polarizations, vertical (V) and horizontal (H) in the frequency band of 6.2 and 5.8 GHz, respectively, due to the presence of two orthogonal H‐shaped slots in its ground plane. The proposed antenna provides a gain enhancement of 9.8 and 10.1 dBi at the respective frequencies. The rectifying circuit is designed for a frequency of 5.8 GHz using a voltage doubler topology. The circuit provides a power conversion efficiency of 41% at 0 dBm input power.     

A Comparative Study of Superconductivity and Thermally Activated Flux Flow of YBa2Cu3O7-δ and YBa2Cu3O7-δ/La1-x-yPrxCayMnO3 Bilayers

Journal of Superconductivity and Novel Magnetism - YBa2Cu3O7-δ/La1-x-yPrxCayMnO3 (YBCO/LPCMO) (x?~?0.31, y?~?0.35) bilayers with fixed ferromagnetic layer thickness...     

A New Energy Efficient Clustering Protocol for a Novel Concentric Circular Wireless Sensor Network

Wireless Personal Communications - Researchers concentrate on big data. Wireless sensor network is one of the sources of big data. Wireless sensor network has hundreds of sensor nodes with limited...     

An Efficient Encoder Architecture Design for Cognitive Radio Networks

Wireless Personal Communications - Interference formation between received symbols in Cognitive Radio (CR) network system is the main problem which reduces the performance of the CR networks. In...     

Effect of phosphotungstic acid blending on properties of sulfonated poly(ether ether ketone)–poly(ethylene glycol) crosslinked membranes

This study shows the effect of phosphotungstic acid (PWA) blended into a sulfonated poly(ether ether ketone) (SPEEK) and poly(ethylene glycol) (PEG) crosslinked membrane on the membrane's electrochemical and mechanical properties. The PWA weight percentage was varied from 0 to 50%. All of the membranes were equilibrated with water at room temperature (27 °C) and elevated temperature (60 °C), and their properties were investigated. A scanning electron microscope with energy dispersive X‐ray was used to ascertain the tungsten concentration remaining in the membrane after water treatment. A systematic decrease in tungsten concentration was seen with the increase in the initial PWA percentage. The membrane blended with 10% PWA showed the best properties, having the highest conductivity (0.11 S cm^?1), mechanical strength, and chemical stability. Membranes with 10% PWA and without PWA were studied in a H₂/O₂ fuel cell. The membrane blended with 10% PWA gave 33% more power density than the membrane without PWA. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46667.     

[Zn(<Emphasis Type="SmallCaps">l</Emphasis>-proline)<Subscript>2</Subscript>] Catalyzed One-Pot Synthesis of Propargylamines Under Solvent-Free Conditions

A simple, one-pot, three-component, green synthesis of a wide range of propargylamines is reported by A³-coupling (aldehyde, alkyne and amine) via C–H activation of alkynes using [Zn(l-proline)₂] as an efficient and reusable heterogeneous catalyst. High catalytic activity was achieved in comparatively low temperature under solvent-free conditions. All reactions were carried out in an open atmosphere without the use of any co-catalyst/additive.

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Cubic‐Like Bimolecular Crystal Evolution and over 12% Efficiency in Halogen‐Free Ternary Solar Cells

In this study, the solubility properties of a given ternary blend set, with two donors (poly(4,8‐bis(5‐(2‐ethylhexyl)thiophen‐2‐yl)benzo[1,2‐b;4,5‐b′]dithiophene‐2,6‐diyl‐alt‐(4‐(2‐ethylhexyl)‐3‐fluorothieno[3,4‐b]thiophene‐)‐2‐carboxylate‐2‐6‐diyl (PTB7‐Th) and benzo[1,2‐b;4,5‐b′]dithiophene‐based small molecule (DR3TSBDT)) and one acceptor ([6,6]‐phenyl‐C₇₁‐butyric acid methyl ester (PC₇₁BM)), in a series of solvents are determined, and active material–solvent interactions are used as an aid for finding suitable nonchlorinated solvents to achieve effective ternary organic solar cells (OSCs) based on PTB7‐Th:DR3TSBDT:PC₇₁BM. An exceptional power conversion efficiency (PCE) as high as 12.3% (certified 11.94%) is obtained using the developed nonhalogenated processing system. In‐depth investigations (morphology, charge mobility, recombination dynamics, and OSC characteristics) uncover the underlying structure–property relationships as a function of the chosen nonhalogenated systems. Another intriguing finding of this study is the formation of a cubic bimolecular crystal structure of PTB7‐Th:PC₇₁BM in a nonhalogenated system, which is the first such demonstration in blend films. This sheds light upon the fact that the physical properties of a material applied from different solutions may surpass the variation in the properties between two material having totally different molecular structure. Therefore, this work not only offers important scientific insights into developing highly efficient and eco‐friendly OSCs but also improves our understanding of achievable bimolecular crystals with an intercalated structure.     

Synthesis, spectroscopic characterization, and thermal decomposition kinetics of some lanthanide(Ⅲ) nitrate complexes of 2-(N-o-hydroxyacetophenone) amino-3-carboxyethyl-4,5,6,7-tetrahydrobenzo[b]thiophene

Complexes of La(Ⅲ), Ce(Ⅲ), Pr(Ⅲ), Nd(Ⅲ), Sm(Ⅲ), Eu(Ⅲ), Gd(Ⅲ), Dy(Ⅲ), Yb(Ⅲ), and Lu(Ⅲ) with 2-(N-o- hydroxyacetophenone)amino-3-carboxyethyl-4,5,6,7-tetrahydrobenzo[b]thiophene (HAAT) formed by the condensation of o-hydroxyacetophenone and 2-amino-3-carboxyethyl-4,5,6,7-tetrahydrobenzo[b]thiophene were synthesized and characterized on the basis of elemental analyses, molar conductance measurements, magnetic susceptibility data, UV-Visible, IR, and NMR spectral studies. The spectral data revealed that the ligand acted as a neutral tridentate coordinating to the metal ion through ONO donor sequence. A coordination number nine was proposed for the complexes. Thermal decomposition studies of the ligand and lanthanum(Ⅲ) complex were carried out and kinetic parameters were calculated using Coats-Redfern equation. The decomposition reactions followed random nucleation mechanism with one nucleus on each particle.     

Surface ultrastructure of gills in relation to the feeding ecology of an angler catfish Chaca chaca (Siluriformes,Chacidae)

Surface ultrastructure of the gills of the angler catfish Chaca chaca was investigated to unravel the adaptive modifications associated with the feeding ecology of the fish. The fish is often found in mud or in soft substrates where they remain buried both for protection and to feed. Gill rakers present on the gill arch in most fish species are absent in this fish. The absence of gill rakers are associated with the feeding habit of the fish and is considered to facilitate the swallowing of captured prey smoothly without any hindrance. Highly corrugated surface of the gill arch and gill filaments could be associated to retain water/mucus to prevent dessicassion of the fish. Papillae like epithelial protuberances each bearing a taste bud at its summit toward the pharyngeal side of the gill arch is associated with the sorting of the food. Large number of mucous goblet cells on the gill arch epithelium are considered to secret copious mucus to lubricate the prey for easy swallowing. In C. chaca the gill septa between gill filaments are reduced. This could enhance the flexibility and permit the free movement of the gill filaments. Extensive secondary lamellae and infrequent mucous goblet cells on secondary lamellae are associated to increase the surface area to enhance efficiency of gaseous exchange.