Improvement of Nanoscale SOI MOSFET Heating Effects by Vertical Gaussian Drain-Source Doping Region

Silicon - This paper presents an efficient method to improve the heating effects in Nanoscale SOI MOSFET with the Vertical Gaussian Doping Profile in Drain and Source regions (D-S-G-SOI). Three...     

Synthesis,characterization, and swelling kinetic study of porous superabsorbent hydrogel nanocomposite based on sulfonated carboxymethylcellulose and silica nanoparticles

New superabsorbent nanocomposite was synthesized by free-radical graft polymerization of sulfonated-carboxymethyl cellulose (SCMC) with acrylic acid (AA) in the presence of polyvinylpyrrolidone (PVP) and silica nanoparticles. Carboxymethyl cellulose (CMC) was first sulfonated using chlorosulfonic acid, and then AA monomers were grafted onto SCMC. FTIR results confirmed that sulfonation of CMC as well as grafting of AA monomers onto SCMC has been performed successfully. Moreover, the presence of silica nanoparticles into superabsorbent nanocomposite was evaluated with EDX analysis. The element mappings show a homogenous distribution of silica nanoparticles throughout the hydrogel nanocomposite. SEM images exhibited porous morphology for hydrogel nanocomposite, which was due to the incorporation of PVP in its network. The experimental findings from TGA analysis indicated that incorporation of PVP and silica nanoparticles into the hydrogel network improved thermal stability of superabsorbent nanocomposite. Swelling kinetic studies revealed that superabsorbent nanocomposite hydrogel had higher equilibrium swelling capacity and swelling rate compared with the neat hydrogel sample. Besides that, superabsorbent nanocomposite depicted excellent salt and pH-sensitive behavior in different saline and pH solutions. As a consequence, this hydrogel nanocomposite acts as useful water reservoir, which might be most profitable in agricultural applications.     

Photocatalytic removal of NOx over immobilized BiFeO<Subscript>3</Subscript> nanoparticles and effect of operational parameters

Perovskite type BiFeO₃ (BFO) was synthesized by sol-gel auto-combustion method. Synthesized BFO was immobilized on the micro slides glass plates by sol-gel dip-coating method. The sample was characterized by XRD, FESEM, UV-Vis DRS, and BET techniques. The XRD pattern confirmed the perovskite structure, and from the Debye-Scherrer equation the average crystalline size was calculated as 19 nm. The FE-SEM images of prepared BFO showed porous structure with low agglomeration. The band gap energy was calculated about 2.13 eV, and the specific surface area (SSA) of prepared BFO nanostructure was obtained 55.1m² g^?1. The photocatalytic activity of prepared pure and immobilized BFO was investigated in the removal of NOx under UV irradiation, in the batch photoreactor. The effects of operational parameters such as initial concentration of NOx, light intensity and amount of coated photocatalyst, under identical conditions, were investigated. The results showed that the highest conversion of NOx was obtained as 35.83% in the 5 ppm of NOx with 1.2 g immobilized BFO and under 15 W illumination lamp.     

Efficient target tracking in directional sensor networks with selective target area’s coverage

Device-to-Device (D2D) communication technology, under the standardization of third generation partnership project and a component of the evolving fifth generation architecture, is mainly aimed to increase system capacity and data rate via providing direct communications between end devices without the use of routing data through the network. Apart from the attracting features, due to the resource sharing between cellular user equipment (CUE) and D2D user equipment (DUE) in such communications, an efficient algorithm for resource and power allocation to DUE, especially for mobile users is necessary to maintain the performance. The current paper introduces a joint mode algorithm for mobile user to choose between cellular and D2D communications and thereby, analyzes resource allocation issues. We propose an efficient algorithm for mobility management of users based on their current connection modes. The locations of D2D pairs are estimated by Levenberg–Marquardt method based on the received signal strength (RSS) from different macrocells. Since the range of D2D communication is much shorter than that of cellular communication, in order to prevent ping-pong handoffs between cellular and D2D modes, we propose the estimation of the next RSS samples in cellular mode prior to switching to D2D mode. In both cellular and D2D modes, the allocated resource block (RB) is the one with the highest signal to interference plus noise ratio (SINR) in order to increase the throughput, under the condition of providing minimum SINR requirement of CUE. This is achieved via transmission power control of the D2D pair. For performance evaluation, we studied the effects of increasing velocity of D2D and cellular users, number of users, and SINR threshold. The results indicate that the proposed solution fairly manages the communication mode of mobile users and incurs improvement in system throughput.     

Electrospun core-shell nanofibers based on polyethylene oxide reinforced by multiwalled carbon nanotube and silicon dioxide nanofillers: A novel and effective solvent-free electrolyte for lithium ion batteries

Insertion of conductive fillers into solvent-free polymer electrolytes enhances electrochemical behavior of the electrolyte membranes leading to higher ionic conductivity, lower capacity fading, and so on. Although, the presence of the conductive fillers in the polymer matrixes increases the risk of electrical shorting, herein, polyethylene oxide (PEO)-based core-shell nanofibers were prepared via a simple electrospinning method. In the core-shell electrospun fibers, ethylene carbonate (EC) and lithium perchlorate (LiClO₄) were used as a plasticizer and as a lithium salt, respectively. The core component was enwrapped by the PEO/EC/LiClO₄ shell part incorporated with SiO₂ nanoparticles. Various properties of the fabricated membranes were evaluated by changing the ratio of multiwall carbon nanotubes (MWCNTs) in the core part of the nanofibers. The morphology and core-shell structure of the electrospun fibers were studied by FESEM and TEM images. According to FTIR and XRD results, addition of the EC plasticizer and the fillers into the as-spun fibers increased the fraction of free ions and the amorphous regions. From electrochemical impedance spectroscopy studies, the ionic conductivity enhanced by insertion of the plasticizer molecules and the filler particles into the core-shell structures. The highest ionic conductivities of 0.09 and 0.21 mS.cm⁻¹ were obtained for the free-filler and the filler-loaded nanofibrous membranes, respectively. The prepared mats obeyed the Arrhenius behavior ( R²~1 ). Dielectric studies confirmed the obtained data from the ionic conductivities. Furthermore, the capacity residual was enhanced from 69% to 85% by incorporation of the MWCNTs filler into the core component of the electrospun nanofibers. The presented results may facilitate development of versatile nanofibrous membranes embedded with the conductive fillers as solvent-free electrolytes applicable in lithium-ion batteries.     

On the encapsulation of natural pesticide using polyvinyl alcohol/alginate–montmorillonite nanocomposite for controlled release application

A representative pesticide, NeemAzal was encapsulated into polyvinyl alcohol/alginate‐montmorillonite (PVA/Alg‐MMT) nanocomposite by cross‐linking with glutaraldehyde. Different formulations of capsule beads containing NeemAzal were prepared with different concentration of materials. Evidence of cross‐linking of PVA and Alg was obtained by comparison of the Fourier transform infrared spectra of the initial substrates and capsule beads. X‐ray diffraction and transmission electron microscopy techniques confirmed the intercalated structure of capsule bead nanocomposites. In addition the swelling behavior of capsule beads was investigated. Results showed that swelling ratio of capsule beads decreases with introduction of MMT as well as increase of PVA content in capsule bead formulations. The release characteristics of NeemAzal from capsule beads were monitored using UV–visible spectrophotometer in distilled water. The addition of sodium MMT to these formulations was found to have a profound inhibitory effect on the release of NeemAzal. Furthermore, the release data were fitted to several empirical equations to estimate the kinetic parameters. The NeemAzal encapsulated PVA/Alg‐MMT nanocomposite capsule beads, designed and discussed in this work, have the potential for controlled release of pesticide. POLYM. ENG. SCI., 54:2707–2714, 2014. © 2013 Society of Plastics Engineers     

Room temperature oxidative intercalation with chalcogen hydrides: Two-step method for the formation of alkali-metal chalcogenide arrays within layered perovskites

A two-step topochemical reaction strategy utilizing oxidative intercalation with gaseous chalcogen hydrides is presented. Initially, the Dion-Jacobson-type layered perovskite, RbLaNb₂O₇, is intercalated reductively with rubidium metal to make the Ruddlesden-Popper-type layered perovskite, Rb₂LaNb₂O₇. This compound is then reacted at room-temperature with in situ generated H₂S gas to create RbS layers within the perovskite host. Rietveld refinement of X-ray powder diffraction data (tetragonal, a = 3.8998(2) Å, c = 15.256(1) Å; space group P4/mmm) shows the compound to be isostructural with (Rb₂Cl)LaNb₂O₇ where the sulfide resides on a cubic interlayer site surrounded by rubidium ions. The mass increase seen on sulfur intercalation and the refined S site occupation factor (～0.8) of the product indicate a higher sulfur content than expected for S^2? alone. This combined with the Raman studies, which show evidence for an HS stretch, indicate that a significant fraction of the intercalated sulfide exists as hydrogen sulfide ion. Intercalation reactions with H₂Se_(g) were also carried out and appear to produce an isostructural selenide compound. The utilization of such gaseous hydride reagents could significantly expand multistep topochemistry to a larger number of intercalants.     

Stress/strain development around a spherical inclusion in a polymeric matrix: The effects of particle and matrix mechanical characteristics and thermal expansivity difference

For a spherical inclusion embedded in an infinite polymeric matrix, the Goodier Model, combined with thermal stress contribution, is applied to establish the stress/strain fields around a spherical particle in different particle/matrix combinations, including TiO₂, alumina, silica, steel, polystyrene, and polyvinyl butyral particles embedded in a range of polymeric matrices. This approach provides the basis for examining the effects of different parameters such as Young's modulus and Poisson's ratio of the particle and matrix, and the thermal history of samples on the failure‐initiation criteria. An explanation is provided for divergent results obtained for very soft and elastic particles. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012