Comparison of different surface orientation in narrow fin MuGFETs

Device performance characteristics are investigated for different surface orientation and doping concentration on accumulation-mode p-type and inversion-mode n-type MuGFETs. Short-channel effects and drain breakdown voltage are better is carrier transport is in the (1 0 0) direction than in the (1 1 0) direction. This is due to the larger Si/SiO₂ interface roughness, the higher density of interface state at (1 1 0) surfaces, and to the difference of effective mass. The mobility in PMOS devices, however, is much higher in the (1 1 0) direction than that in the (1 0 0) direction. For better performance of device, our results show that optimized fin orientation can improve device stability and performance.     

Numerical simulation of planar shear flow passing a rotating cylinder at low Reynolds numbers

Two-dimensional shear flow over a rotating circular cylinder is investigated using lattice Boltzmann method. Simulations are performed at a fixed blockage ratio (B = 0.1) while the Reynolds number, nondimensional shear rate (K) and absolute rotational speed range as 80 ≤ Re ≤ 180, 0 ≤ K ≤ 0.2 and −2 ≤ β ≤ 2, respectively. To verify the simulation, the results are compared to previous experimental and numerical data. Quantitative information about the flow variables such as drag and lift coefficients, pressure coefficient and vorticity distributions on the cylinders is highlighted. It is found that, generally, with the increment in |β|, the absolute value of time average lift coefficient increases and time average drag coefficient decreases, and beyond a certain magnitude of β, the vortex shedding vanishes. It is also revealed that the drag coefficient decreases as the Reynolds number increases while the effect of the Reynolds number on lift is almost negligible. At the end, correlations for drag and lift coefficients ([`(C<sub>D</sub> )] ,[`(C_L )]){(\overline {C_D } ,\overline {C_L })} are extracted from the numerical data.     

Terahertz graphene optics

The magnitude of the optical sheet conductance of single-layer graphene is universal, and equal to e ²/4? (where 2??? = h (the Planck constant)). As the optical frequency decreases, the conductivity decreases. However, at some frequency in the THz range, the conductivity increases again, eventually reaching the DC value, where the magnitude of the DC sheet conductance generally displays a sample- and doping-dependent value between ??e ²/h and 100 e ²/h. Thus, the THz range is predicted to be a non-trivial region of the spectrum for electron transport in graphene, and may have interesting technological applications. In this paper, we present the first frequency domain measurements of the absolute value of multilayer graphene (MLG) and single-layer graphene (SLG) sheet conductivity and transparency from DC to 1 THz, and establish a firm foundation for future THz applications of graphene.      

Boost-wise pre-loaded mixture of experts for classification tasks

A modified version of Boosted Mixture of Experts (BME) is presented in this paper. While previous related works, namely BME, attempt to improve the performance by incorporating complementary features of a hybrid combining framework, they have some drawback. Analyzing the problems of previous approaches has suggested several modifications that have led us to propose a new method called Boost-wise Pre-loaded Mixture of Experts (BPME). We present a modification in pre-loading (initialization) procedure of ME, which addresses previous problems and overcomes them by employing a two-stage pre-loading procedure. In this approach, both the error and confidence measures are used as the difficulty criteria in boost-wise partitioning of problem space.

     

Nanostructured silver fibers: Facile synthesis based on natural cellulose and application to graphite composite electrode for oxygen reduction

The development of cheaper electrocatalysts for fuel cells is an important research area. This work proposes a new, simpler and low-cost approach to develop nanostructured silver electrocatalysts by using natural cellulose as a template. Silver was deposited by reduction of Ag complexes on the surface of cellulose fibers, followed by heat removal of the template to create self-standing nanostructured silver fibers (NSSFs). X-Ray diffraction (XRD) showed fcc silver phase and X-Ray photoelectron spectroscopy (XPS) demonstrated that the surface was partially oxidized. The morphology of the fibers consisted of 50 nm nanoparticles as the building blocks, and they possessed a specific surface area of about 25 m²/g, which is sufficiently high for electrocatalytic applications. The NSSFs were incorporated in a graphite composite electrode. The resulting modified electrode displayed a good electrocatalytic activity for the reduction of dissolved oxygen in basic media. In an O₂-saturated 0.1 M KOH solution, the overpotential to initiate the oxygen reduction reaction reduced and the limiting current increased by increasing the relative amount of silver fibers from 0 to 5 wt%.     

Gradient Origami Metamaterials for Programming Out-of-Plane Curvatures

Origami structures are a traditional Japanese art that have recently found their way into engineering applications due to their powerful capability to transform flat 2D structures into complex 3D structures along their creases. This has given a rise to their application as designer materials with unprecedented mechanical characteristics, also known as metamaterials. Herein, gradient Miura-ori origami metamaterials are introduced as a method to preprogram out-of-plane curvatures. Several types of unit cell distributions in the origami lattice structure including checkered, linear gradient, concave radial gradient, convex radial gradient, and striped are considered. The results show that these distributions of Miura-ori origami can create single- or double curvatures including twisting, saddling, bending, local inflation, local twisting, local bending, and wavy shapes, when the origami metamaterial is loaded in compression. All the Gaussian curvatures (negative, positive, and zero) can be achieved using the proposed models. The approach helps tailoring complex preprogrammed surface geometries by employing linearly varying gradient distributions of Miura-ori origami.     

A Robust Intrinsically Green Fluorescent Poly(Amidoamine) Dendrimer for Imaging and Traceable Central Nervous System Delivery in Zebrafish

Intrinsically fluorescent poly(amidoamine) dendrimers (IF‐PAMAM) are an emerging class of versatile nanoplatforms for in vitro tracking and bio‐imaging. However, limited tissue penetration of their fluorescence and interference due to auto‐fluorescence arising from biological tissues limit its application in vivo. Herein, a green IF‐PAMAM (FGP) dendrimer is reported and its biocompatibility, circulation, biodistribution and potential role for traceable central nervous system (CNS)‐targeted delivery in zebrafish is evaluated, exploring various routes of administration. Key features of FGP include visible light excitation (488 nm), high fluorescence signal intensity, superior photostability and low interference from tissue auto‐fluorescence. After intravenous injection, FGP shows excellent imaging and tracking performance in zebrafish. Further conjugating FGP with transferrin (FGP‐Tf) significantly increases its penetration through the blood–brain barrier (BBB) and prolongs its circulation in the blood stream. When administering through local intratissue microinjection, including intracranial and intrathecal injection in zebrafish, both FGP and FGP‐Tf exhibit excellent tissue diffusion and effective cellular uptake in the brain and spinal cord, respectively. This makes FGP/FGP‐Tf attractive for in vivo tracing when transporting to the CNS is desired. The work addresses some of the major shortcomings in IF‐PAMAM and provides a promising application of these probes in the development of drug delivery in the CNS.     

Emerging Biofabrication Strategies for Engineering Complex Tissue Constructs

The demand for organ transplantation and repair, coupled with a shortage of available donors, poses an urgent clinical need for the development of innovative treatment strategies for long‐term repair and regeneration of injured or diseased tissues and organs. Bioengineering organs, by growing patient‐derived cells in biomaterial scaffolds in the presence of pertinent physicochemical signals, provides a promising solution to meet this demand. However, recapitulating the structural and cytoarchitectural complexities of native tissues in vitro remains a significant challenge to be addressed. Through tremendous efforts over the past decade, several innovative biofabrication strategies have been developed to overcome these challenges. This review highlights recent work on emerging three‐dimensional bioprinting and textile techniques, compares the advantages and shortcomings of these approaches, outlines the use of common biomaterials and advanced hybrid scaffolds, and describes several design considerations including the structural, physical, biological, and economical parameters that are crucial for the fabrication of functional, complex, engineered tissues. Finally, the applications of these biofabrication strategies in neural, skin, connective, and muscle tissue engineering are explored.     

Fatigue behaviour of additive manufactured materials: An overview of some recent experimental studies on Ti‐6Al‐4V considering various processing and loading direction effects

Although additive manufacturing (AM) has gained significant attention due to the advantages it offers and is currently a focus of much research, design of critical load carrying components utilizing such processes is still at its infancy. This is due to the fact that most of the load carrying components made by AM processes are subjected to cyclic loads, and fatigue behaviour of AM metals is far less understood as compared with those made by conventional methods, such as wrought and cast metals. To better understand the fatigue behaviour of AM metals, a wide range of issues that affect the behaviour in a synergistic manner must be considered. These include the effects of defects, residual stresses, surface finish, geometry and size, layer orientation, and heat treatment. Additionally, due to the multiaxial nature of the loading and/or complex geometries typically manufactured by AM processes, the stress state is often multiaxial including both normal and shear stresses. In this paper, the aforementioned effects influencing the fatigue resistance of AM parts, including torsion and multiaxial fatigue behaviour, are briefly discussed using some recently generated experimental data on Ti‐6Al‐4V by the authors.