Effect of Channel Width Variation on Electrical Characteristics of Double Lateral Gate Junctionless Transistors; A Numerical Study

In this paper, the effect of channel width variation on performance of double lateral gate junctionless transistors in the depletion and accumulation regimes is investigated. The characteristics of the device with various channel widths is comprehensively examined through analysis of on and off state current, threshold voltage (V _th), transconductance (g _m) and drain conductance (g _D) variation in each operating regime. The carriers’ density distribution, electric field components and mobility are investigated through 3-D numerical simulations of the device to illustrate the variation of output characteristics. The results show that as the width decreases, the off-current (I _OFF) decreases significantly as a result of better electrostatic control of the lateral gates over the channel. The on-current (I _ON) is also decreased mainly due to the doping-dependent mobility degradation.It is also indicated that between the flat-band and fully depleted (pinch off) variation of the majority carriers is the main parameter that modifies the characteristics of the device, while the mobility variation is recognized as the basic factor in the accumulation regime.     

Effect of seed layers on low-temperature,chemical bath deposited ZnO nanorods-based near UV-OLED performance

Low-temperature wet chemical bath deposition (CBD) method is one of the most efficient and least hazardous solution-based techniques which is widely employed to grow ZnO NRs. In CBD method, a seed layer is usually deposited on the substrate. In this paper, high quality ZnO and aluminum doped ZnO (AZO) seed layers are sputtered on the indium tin oxide (ITO) coated glass. In continue, aligned ZnO NRs are grown on the AZO and ZnO seed layers via CBD technique. The effect of the growth time and seed layer on the physical properties of as-grown ZnO NRs are investigated. According to the results, the seed layer plays an essential role on the growth orientation and growth rate of the ZnO NRs. The ZnO NRs grown on AZO seed layer are more aligned rather than ZnO seed layer due to their higher texture coefficients. The relative photoluminescence (PL) intensity ratio of near band emission (NBE) to deep level emission (DLE) (I_NBE/I_DLE) for the ZnO NRs grown on AZO and ZnO seed layers are calculated as 7.45 and 2.62, respectively. To investigate the performance of the as-grown ZnO NRs, near ultraviolet organic light-emitting diodes (UV-OLEDs) using ZnO NRs array as n-type material and poly [2-methoxy-5-(2-ethyl-hexyloxy)-1,4-phenylene-vinylene] (MEH-PPV) conjugated polymer as p-type material have been fabricated. The total concentration of traps ($N_t$), the characteristic energies ($E_t$) and the turn-on voltages for the devices with the structures of ITO/AZO/ZnO NRs/MEH-PPV/Al (device A) and ITO/ZnO/ZnO NRs/MEH-PPV/Al (device B) are attained 7.65 × 10¹⁶ and 7.75 × 10¹⁶ cm^?3, 0.232 and 0.206 eV, 23 and 21 V, respectively. Moreover, based on the electroluminescence (EL) spectra, the NBE peaks for device A and B are obtained nearly in the wavelengths of 382 and 388 nm, respectively. Finally, various charge carrier transportation processes of prepared UV-OLEDs have been studied, systematically.     

An energy-efficient method for mitigating membrane fouling: A novel embodiment of the inverse fluidized bed

A novel inverse fluidized bed (IFB) was developed to improve membrane fouling mitigation vis-à-vis the conventional aeration method. The fluidized media, whose density was less than water and oleophilic, were more effective than bubbles for both feeds containing oil and particulates due to their greater inertia. The key highlights are (i) for all the conditions investigated, IFB consistently gave a lower trans-membrane pressure (TMP) than aeration at the same energy requirement; (ii) IFB performed better even when the energy input was reduced by 87.5%; (iii) IFB provided an impressive enhancement of up to 54 times that of dead-end filtration.     

All-optical 6- and 8-channel demultiplexers based on photonic crystal multilayer ring resonators in Si/C rods

In this paper, we employed multilayer ring resonators in a silicon rod base structure to realize 6-channel and 8-channel demultiplexers based on two-dimensional photonic crystals. Both the main rings and basic structures are composed of silicon rods, and the interior rings of the multilayer rings are composed of carbon. Employing silicon and carbon rods of different radii in multilayer ring resonators enhanced the coupling efficiency between the rings and waveguides. The average quality factor and power transmission efficiency were 4320 and 93%, respectively. Crosstalk values from \(-11\) to ?46 dB in conjunction with the mentioned characteristics suggest the use of the device for optical communication applications. The compact size of the proposed structure and the materials used make the proposed demultiplexer suitable for optical integrated circuits.     

Synthesis of sulfides via reaction of aryl/alkyl halides with S8 as a sulfur-transfer reagent catalyzed by Fe3O4-magnetic-nanoparticles-supported L-Histidine-Ni(II)

One-pot synthesis of symmetrical diaryl/alkyl sulfides in high yields from the reaction between aryl/alkyl halides and S₈ can be carried out in a short period, using Fe₃O₄@SiO₂@His@Ni(II) as a reusable catalyst. The present approach offers the advantages of a clean reaction, simple methodology and high efficiency, and avoids the use of a toxic catalyst.     

Design and fabrication of a high-efficiency extreme-ultraviolet binary phase-only computer-generated hologram

As the development of extreme-ultraviolet (EUV) lithography progresses, interest grows in the extension of traditional optical components to the EUV regime. The strong absorption of EUV by most materials and its extremely short wavelength, however, make it very difficult to implement many components that are commonplace in the longer wavelength regimes. One such component is the diffractive optical element used, for example, in illumination systems to efficiently generate modified pupil fills. The fabrication and characterization of an EUV binary phase-only computer-generated hologram is demonstrated, allowing arbitrary far-field diffraction patterns to be generated. Based on reflective architecture, the fabricated device is extremely efficient. Based on an identically fabricated null hologram, the absolute efficiency into one diffracted order of 22% has been demonstrated. In the case where axially symmetric diffraction patterns are desired (both positive and negative diffraction orders can be used), the efficiency can be twice as high.     

A hybrid discontinuous spectral element method and filtered mass density function solver for turbulent reacting flows

Abstract

We present a novel hybrid scheme for the large eddy simulation (LES) of turbulent reacting flows. The scheme couples the discontinuous spectral element method (DSEM) solver for the unsteady compressible Navier-Stokes equations with a Monte Carlo particle filtered mass density function (FMDF) solver for the transport of reacting species. The method is capable of high-order simulations on unstructured grids. Mean particle estimate construction mimics the DSEM numerical procedure and utilizes variable basis functions. The scheme is tested on non-reacting and reacting Taylor-Green vortex flows. Studies of varying polynomial order, different basis functions for constructing particle estimates, and varying particle quantities are conducted. We demonstrate that a tent kernel, in conjunction with high polynomial order, produces the most accurate results. The chemically reacting simulations validate the hybrid scheme and demonstrate its applicability across a range of reaction regimes. The hybrid scheme's computational cost is 2.1 times the DSEM-LES solver.     

Polymerization of Triazolinediones with trans-3,3-Dichloro-1-phenyl-1-propene

The reaction of 4-phenyl-1,2,4-triazoline-3,5-dione (PhTD) ( 2 ) with trans-3,3-dichloro-1-phenyl-1-propene ( 4 ) was investigated at room and reflux temperatures in methylene chloride solution. Although the reaction is slow, it gives quantitative yield. This reaction leads to the formation of two 2:1 adducts via double Diels–Alder and Diels–Alder-Ene reactions in a ratio of about 1: 7. The major product was isolated by means of fractional crystallization as a pure compound and was characterized by infra-red (IR), ¹H nuclear magnetic resonance (NMR), ¹³C NMR, mass spectra and elemental analysis. The structure of the minor product was determined by IR and ¹H NMR. These compounds were used as models for the polymerization reactions. The reaction of bistriazolinediones (1,6-bis-(3,5-dioxo-1,2,4-triazoline-4-yl)hexane and bis-(p-3,5-dioxo-1,2,4-triazoline-4-ylphenyl)methane) with ( 4 ) was carried out in dimethylformamide (DMF). The reactions gave novel polymers via repetitive double Diels–Alder and Diels–Alder-Ene polyaddition reactions, with the major component being a Diels–Alder-Ene structure. These polymers have intrinsic viscosities in a range from 0·08 to 0·18dlg^-1 in DMF. The physical properties and structural characterization of these polymers have been studied and are reported. © of SCI.     

The era of sustainable agricultural development in Africa: Understanding the benefits and constraints

Sustainable agriculture has the potential to address some of the fundamental challenges facing agricultural practices in Africa especially in Sub-Saharan Africa (SSA). The agriculture sector plays an important role as the engine of economic growth in SSA. In this article, we ask the following key question: Can sustainable agriculture save Africa from poverty and food insecurity? To address this fundamental question, we examine and critique evidence of the benefits and challenges associated with the adoption of sustainable agricultural practices in Africa. Improving agricultural sustainability is fundamental to food security and poverty reduction, particularly in achieving elements of the sustainable development goals (SDGs) by 2030, but it will not solve all these problems alone. In consort, African governments and the international community must increase their efforts in tackling problems such as conflicts, civil war, political instability, and disease. Therefore, agricultural policy at the national, regional, and local levels and institutional reforms must be designed to benefit food security, poverty reduction, and income growth at the household level.     

Numerical simulation of steady natural convection heat transfer in a 3-dimensional single-ended tube subjected to a nanofluid

In this paper, 3-dimensional numerical simulation of steady natural convective flow and heat transfer are studied in a single-ended tube with non-uniform heat input. Apart from some other applications, it serves as a simplified model of the single-ended evacuated solar tube of a water-in-glass evacuated tube solar water heater. It is assumed that the sealed end of tube to be adiabatic and also the tube opening to be subjected to copper–water nanofluid. Governing equations are derived based on the conceptual model in the cylindrical coordinate system. The governing equations have been then approximated by means of a fully implicit finite volume control method (FVM), using SIMPLE algorithm on the collocated arrangement. The study has been carried out for solid volume fraction 0 ≤ φ ≤ 0.05 and maximum heat flux 100 ≤ q_m ≤ 700. Considering that the driven flow in the tube is influenced by the dimensions and the inclination angle of the solar tube, the flow patterns and temperature distributions are presented on different cross sectional planes and longitudinal sections, when the tube is positioned at different orientations.