A low-power 2.4-GHz transmitter/receiver CMOS IC

A 2.4-GHz CMOS receiver/transmitter incorporates circuit stacking and noninvasive baseband filtering to achieve a high sensitivity with low power dissipation. Using a single 1.6-GHz local oscillator, the transceiver employs two upconversion and downconversion stages while providing on-chip image rejection filtering. Realized in a 0.25-/spl mu/m digital CMOS technology, the receiver exhibits a noise figure of 6 dB and consumes 17.5 mW from a 2.5-V supply, and the transmitter delivers an output power of 0 dBm with a power consumption of 16 mW.     

One-Pot Three-Component Synthesis of 2,4,5-Triaryl-1H-imidazoles Using Mn2+ Complex of [7-Hydroxy-4-methyl-8-coumarinyl] Glycine as a Heterogeneous Catalyst

Catalysis Letters - A highly efficient and simple synthesis of 2,4,5-trisubstituted imidazoles has been developed using highly reusable support‐free Mn2+complex of...     

Ferrimagnetic Skyrmions in Topological Insulator/Ferrimagnet Heterostructures

Magnetic skyrmions are topologically nontrivial chiral spin textures that have potential applications in next-generation energy-efficient and high-density spintronic devices. In general, the chiral spins of skyrmions are stabilized by the noncollinear Dzyaloshinskii–Moriya interaction (DMI), originating from the inversion symmetry breaking combined with the strong spin–orbit coupling (SOC). Here, the strong SOC from topological insulators (TIs) is utilized to provide a large interfacial DMI in TI/ferrimagnet heterostructures at room temperature, resulting in small-size (radius ≈ 100 nm) skyrmions in the adjacent ferrimagnet. Antiferromagnetically coupled skyrmion sublattices are observed in the ferrimagnet by element-resolved scanning transmission X-ray microscopy, showing the potential of a vanishing skyrmion Hall effect and ultrafast skyrmion dynamics. The line-scan spin profile of the single skyrmion shows a Néel-type domain wall structure and a 120 nm size of the 180° domain wall. This work demonstrates the sizable DMI and small skyrmions in TI-based heterostructures with great promise for low-energy spintronic devices.     

Dissimilar joining of Al/Mg light metals by compound casting process

“Compound casting” was used for production of lightweight Al/Mg couples. In order to prepare the Al/Mg couples using this process, each of the aluminum and magnesium molten metal was cast around solid cylindrical inserts of the other metal. After solidification, the interfacial microstructure and shear strength of the joint were studied. Characterization of Al/Mg interface by an optical microscope and scanning electron microscope showed that in the case of casting aluminum melt around a magnesium insert, a gap is formed at the interface, while in the process of casting magnesium melt around an aluminum insert, a relatively uniform interface composed of three different layers is formed at the interface. The results of the X-ray diffraction, energy dispersive X-ray spectroscopy, wavelength dispersive X-ray spectroscopy, and microhardness analysis of the interface showed that these three layers are mainly composed of high-hardness Al–Mg intermetallic compounds. Furthermore, it was found that the thickness of the interface is not constant throughout Al/Mg joint, and varies gradually from 190 μm at the bottom to 140 μm in the middle and 50 μm at the top of the sample. The results of shear strength tests obviously showed that the strength of the interface depends on the interface thickness and increases by decreasing the thickness of the interface.     

The influence of different plasticisers and fatty acids on functional properties of basil seed gum edible film

In this study, the influence of different concentrations of plasticisers and fatty acids on functional properties of basil seed gum (BSG) films was investigated. The results revealed that glycerol and sorbitol were effective plasticisers for BSG films. Glycerol‐plasticised films exhibited hydrophilic nature with high moisture content (27–49%) and water vapour permeability (4.2–6.5 × 10^?11 g Pa^?1 m^?1 s^?1), moisture uptake higher than 100%, solubility ranging 39–50% and moderate mechanical properties. The films containing sorbitol showed lower moisture content, moisture uptake and percentage elongation compared with glycerol‐plasticised samples. Presence of fatty acids promoted an increase in hydrophobicity of samples, characterised by lower moisture uptake, solubility, water vapour permeability and higher contact angles. Among investigated fatty acids, oleic acid efficiency on improving the characteristics of films was higher than saturated fatty acids (palmitic and stearic acid). Concluding, BSG films showed a substantial potential to be incorporated into food packaging applications, especially for those that require less hydrophilic films.     

Effect of A-site cation size on magnetic and charge-ordering properties of Ln0.5Sr0.5Mn0.9Cu0.1O3 (Ln = La,Pr, Nd,or Ho)

The structural, magnetic, and electrical properties of Ln_0.5Sr_0.5Mn_0.9Cu_0.1O₃ (Ln = La, Pr, Nd, or Ho) perovskite manganites have been investigated to explore the influence of A-site cation radius (〈r_A〉) and the A-site cation size-disorder (σ²) on the various interdependent phenomena such as ferromagnetism (FM), phase separation (PS), and charge ordering (CO). The temperature dependence magnetization (M–T) curve of La-based sample shows four distinct points at ∼269 K, 255 K, 200 K, and 148 K corresponding to strong FM, cluster glass (CG), weak FM, and charged ordered antiferromagnetic (COAFM) transitions, respectively. Our investigation shows that Neel temperatures (T_N) increases, whereas Curie (T_C) and irreversibility temperatures (T_irr) decrease with decreasing 〈r_A〉, i.e., with increasing σ². Furthermore, the value of the magnetization decreases and resistivity increases with decreasing 〈r_A〉. All samples exhibit insulating behavior in the temperature range 77–300 K and above 110 K the electronic conduction mechanism has been described within the framework of the variable range hopping (VRH) model.     

Investigation of combination of finite element formulation and element type on the accuracy of 3D modeling of polymeric fluid flow in an extrusion die

The aim of this work is to investigate the effect of finite element formulation and element type on the accuracy of 3D modeling of generalized Newtonian fluid flow in complex domains. Computer models based on three finite element solution schemes (mixed, continuous, and discrete penalty), and two element types (hexahedral and tetrahedral) in a 3D framework were developed. The well‐known Carreau model was used to reflect the rheological behavior of the fluid. To determine the validity of the developed computer simulations, the flow of two high‐density polyethylene (HDPE) melts with different viscosities through an extrusion die was simulated and compared with experimentally measured data. Comparison showed that the three methods produced nearly the same results with the hexahedral elements. However, continuous penalty method using tetrahedral elements demonstrated an extreme discrepancy from the experimental data. Discrete penalty method was unable to predict secondary variable (pressure) accurately using tetrahedral elements. The best results were obtained by the use of mixed method in conjunction with tetrahedral elements. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011