Cost-effective fabrication of memristive devices with ZnO thin film using printed electronics technologies

A prototype memristive device has been presented in this paper, for which the top and bottom electrodes have been fabricated through a simple and cost-effective technique, i.e. electrohydrodynamic printing. For deposition of the bottom electrode pattern, a silver ink containing 60 wt% silver by content was subjected to controlled flow through a metal capillary exposed to an electric field at the ambient temperature to generate an electrohydrodynamic jet, thereby depositing uniform patterns of silver on glass substrate at a constant substrate speed. The top electrode has been deposited in a similar fashion. In between the top and bottom electrodes, a uniform layer of ZnO is fabricated using spin-coating technique. The nanoscale ZnO memristor stack has a channel length of 370 μm and channel width of 82 μm. A memristor thus fabricated was characterized and its current voltage curves were analyzed. The device showed a typical nonvolatile resistive switching behavior present in memristor devices thus highlighting the EHD printed patterning as a reliable method for the fabrication of memory devices.     

Effect of heat generation on transient flow of micropolar fluid in a porous vertical channel

The present work is performed to study the effect of heat generation on fully developed flow and heat transfer of micropolar fluid between two parallel vertical plates. The rigid plates are assumed to exchange heat with an external fluid by convection. The governing equations are solved by using Crank–Nicolson implicit finite difference method. The effects of governing parameters such as transient, heat generation, micropolar parameter, Prandtl number, Biot number, and Reynolds number on the velocity and temperature profiles are discussed. It is found that the presence of heat generation enhances the velocity and temperature of the micropolar fluid at the middle of the channel.     

Infrared reflectivity spectra of <Emphasis Type="Italic">η</Emphasis>-Na<Subscript>1.3</Subscript>V<Subscript>2</Subscript>O<Subscript>5</Subscript> in the charge disordered and ordered phase

We have measured the far-infrared reflectivity spectra of the sodium vanadium oxide η-Na_1.3V₂O₅ polycrystals in the wide temperature (80–300 K) and frequency (150–1500 cm⁻¹) range. Appearance of new phonon oscillators, phonon oscillator mode splitting and step-like shift of TO and LO frequencies at low temperatures are correlated with the charge-ordering phase transition, which takes place at about 120 K in this vanadium oxide.     

Low-frequency Raman scattering from CeO<Subscript>2</Subscript> nanoparticles

Raman scattering measurements were performed on CeO₂ nanoparticles at room temperature. Low-frequency modes are assigned to confined acoustic vibrations of spherical CeO₂ nanoparticles. Frequencies of these vibrational modes have been calculated in the elastic continuum approximation, which considers a nanoparticle as a homogeneous elastic sphere. We assumed stress-free boundary conditions. The specific dependence of the vibrational frequency on the particle diameter enables the determination of the particle size from the experimental Raman frequency. The particle size value calculated in this way agrees well with the value acquired from the phonon confinement model. PACS 61.46.Df; 73.63.Bd; 63.22.+m     

Holographic Three-Dimensional Display Using an Electron-Beam-Addressed Spatial Light Modulator

Three-dimensional (3-D) or holographic information extracted by two-dimensional active optical heterodyne scanning has been demonstrated recently. The technique is called optical scanning holography. To reconstruct the obtainable 3-D holographic information, digital techniques have been used and demonstrated. For real-time applications, we need to investigate spatial-light-modulator-based systems. In this paper, we first briefly review optical scanning holography, and then present experimental results of 3-D image reconstruction using an electron-beam-addressed spatial light modulator.     

The sixth Asian Symposium on Visualization

The sixth Asian Symposium on Visualization (ASV6) was successfully held from May 28th to 31st, 2001 in Busan, Korea. The activities of the organizing committee and ASV6 programs are outlined here in retrospect and the philosophy of ASV6 is described.     

Antiferromagnetic order in doped hubbard model under the magnetic field

We investigate the effects of temperature and hole doping on the antiferromagnetic (AF) ground states by considering the system of electrons on a two dimensional square lattice under the external magnetic field. In the mean field calculation of Hubbard Hamiltonian we find out that the magnetic field suppresses the AF order in a unique manner for all parameter values ofT and δ. We obtained the phase diagram of AF order inT-δ plane as a function of Coulomb correlation strength and magnetic field. We find the reentrant behavior of AF order in both the absence and the presence of magnetic field.     

Iron chelator induces MIP-alpha/CCL20 in human intestinal epithelial cells: implication for triggering mucosal adaptive immunity

A previous report by this laboratory demonstrated that bacterial iron chelator (siderophore) triggers inflammatory signals, including the production of CXC chemokine IL-8, in human intestinal epithelial cells (IECs). Microarray-based gene expression profiling revealed that iron chelator also induces macrophage inflammatory protein 3 alpha (MIP-3alpha)/CC chemokine-ligand 20 (CCL20). As CCL20 is chemotactic for the cells involved in host adaptive immunity, this suggests that iron chelator may stimulate IECs to have the capacity to link mucosal innate and adaptive immunity. The basal medium from iron chelator deferoxamine (DFO)-treated HT-29 monolayers was as chemotactic as recombinant human CCL20 at equivalent concentrations to attract CCR6(+) cells. The increase of CCL20 protein secretion appeared to correspond to that of CCL20 mRNA levels, as determined by real-time quantitative RT-PCR. The efficacy of DFO at inducing CCL20 mRNA was also observed in human PBMCs and in THP-1 cells, but not in human umbilical vein endothelial cells. Interestingly, unlike other proinflammatory cytokines, such as TNF-alpha and IL-1beta, a time-dependent experiment revealed that DFO slowly induces CCL20, suggesting a novel mechanism of action. A pharmacologic study also revealed that multiple signaling pathways are differentially involved in CCL20 production by DFO, while some of those pathways are not involved in TNF-alpha-induced CCL20 production. Collectively, these results demonstrate that, in addition to some bacterial products known to induce host adaptive immune responses, direct chelation of host iron by infected bacteria may also contribute to the initiation of host adaptive immunity in the intestinal mucosa.     

Mixed convection of heat generating nanofluid in a lid-driven cavity with uniform and non-uniform heating of bottom wall

Steady state two-dimensional mixed convection in a lid-driven square cavity filled with Cu  –water nanofluid is investigated numerically in the presence of internal heat generation. In the present investigation, bottom wall is uniformly and non-uniformly heated while two vertical walls are fixed and they are thermally insulated. The top wall is moving from left to right at a constant speed. The governing equations are normalized and solved numerically with boundary conditions by finite volume approach using third order accurate upwinding scheme (deferred QUICK). Effects of the pertinent physical parameters are investigated in terms of the flow and temperature fields, as well as Nusselt number distributions. The presented results show that the solid volume fraction plays a significant role on the flow and thermal fields and the Nusselt number distributions for different flow configurations. It is found that Richardson number strongly affect the fluid flow and heat transfer in the cavity. For Ri<1$\mathit{Ri}<1$, the forced convection becomes dominant in the entire cavity, the natural convection relatively weak.