Experimental study of resistive bistability in metal oxide junctions

We have studied resistive bistability (memory) effects in junctions based on metal oxides, with a focus on sample-to-sample reproducibility, which is necessary for the use of such junctions as crosspoint devices of hybrid CMOS/nanoelectronic circuits. Few-nm-thick layers of NbO _x , CuO _x and TiO _x have been formed by thermal and plasma oxidation, at various deposition and oxidation conditions, both with and without rapid thermal post-annealing. The resistive bistability effect has been observed for all these materials, with particularly high endurance (over 10³ switching cycles) obtained for single-layer TiO₂ junctions, and the best reproducibility reached for multi-layer junctions of the same material. Fabrication optimization has allowed us to improve the OFF/ON resistance ratio to about 10³, but the sample-to-sample reproducibility is so far lower than that required for large-scale integration.     

A model for simulation of crowd behaviour in the evacuation from a smoke-filled compartment

The modelling of crowd evacuation from a building has been studied over the past decades. In this study, a numerical model based on cellular automaton is proposed to simulate the human behaviour termed “flow with the stream” in emergency evacuation from a large smoke-filled compartment. In the model, the smoke effect in the context of visibility is considered since visibility range can affect the human behaviour significantly. To simulate the reality that the smoke concentration in a fire compartment is not constant, the proposed model is developed to deal with the scenario in which the visibility range varies in the course of time. An empirical formula is incorporated into the proposed model to estimate the visibility range. The results of numerical tests show that the proposed model can also be used to investigate the effect of the number of guiders through case study.     

Performance of a satellite-to-ground downlink coherent lasercom system with random tracking error of receiver

We analyze the performance of a satellite-to-ground downlink coherent lasercom system taking into account the combined effects of atmospheric wavefront aberration and tracking error of the receiver. We revise the wavefront phase variance in the case where the tracking error of the receiver terminal is present. We consider the example of the BPSK modulation scheme and show that the tracking error of the receiver terminal greatly increases the bit error probability of the coherent system. We show the optimum aperture diameter of the receiver. This study can benefit the satellite-to-ground downlink coherent lasercom system design.     

Electrochemical characterization of the redox couple of Fe(III)/Fe(II) mediated by grafted polymer electrode

A new grafted polymer electrode (GPE) (polystyrene as polymer) was grafted with acrylonitrile as a monomer using gamma irradiation to produce a new grafted polymer. The redox process of K₃Fe(CN)₆ during cyclic voltammetry was studied by the new GPE. The ratio of Ipc/Ipa >1 of GPE to GCE Ipc/Ipa = 1.7, indicating that this electrode is a reversible electrode and can be used in conductivity studies by voltammetric analysis. The physical properties of the new electrode GP have good hardness, insolubility, and stability at different high temperatures and at different pH. Also, the sensitivity under conditions of cyclic voltammetry is significantly dependent on pH, electrolyte, and scan rate. At different scan rates, two oxidation peaks and two reduction peaks of Fe(III) were observed in a reversible process: Fe(III) Fe(II), and Fe(II) Fe(0). Interestingly, the redox reaction of Fe(III) solution using GPE remained constant even after 15 cycles. It is therefore evident that the GPE possesses some degree of stability. The potential use of the grafted polymer as a useful electrode material is therefore clearly evident.     

A one-pot tandem synthesis of various 1,2-disubstituted benzimidazoles

A facile method to synthesize various 1,2-disubstituted benzimidazoles is developed. It is suggested that formation of a Meisenheimer adduct between the substrate, amine, and solvent aids the N-arylation process. The generality of the protocol is demonstrated by the efficient reactions involving numerous substituents ranging from electron-withdrawing groups to electron-donating groups.     

Synthesis of 2‐Arylbenzoxazoles from Flash Vacuum Pyrolysis of 2‐Methoxy‐N‐(arenylidene)anilines

Flash vacuum pyrolysis of 2‐methoxy‐N‐(arenylidene)anilines 2a‐g at 700 °C and 1 × 10^‐2 Torr gave the corresponding 2‐arylbenzoxazoles 1a‐g .     

A novel eudesmene sesquiterpenoid from <Emphasis Type="Italic">Schisandra sphenanthera</Emphasis> stems

Chemical investigation on the stems of Schisandra sphenanthera has afforded a novel eudesmene-type sesquiterpenoid, schisansphene A (1), and a known compound, alismol (2). Their structures and configurations were elucidated by spectroscopic methods, including 2D NMR techniques.     

A Facile Oxidation of Thiols to Disulfides Catalyzed by CoSalen

Abstract

A convenient and facile catalytic oxidation of thiols to the corresponding disulfides is described using CoSalen as the catalyst and air as the oxidizing agent. This new approach provides an efficient method for the preparation of symmetrical disulfides in high yields and under mild conditions.

[Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements for the following free supplemental resource: Spectroscopic Identification of Products 3a–3l.]     

Numerical Study on the Dynamics and Oxygen Uptake of Healthy and Malaria-Infected Red Blood Cells

Red blood cells (RBCs) are very important due to their role of oxygen transport from lungs. As the malaria parasite grows in the malaria-infected red blood cells (IRBCs), the properties of the cells change. In the present work, the oxygen uptake by RBCs and IRBCs at the pulmonary capillaries is simulated using a numerical technique based on the two-dimensional immersed interface method. The results for the oxygen uptake by a stationary single RBC have fair agreements with the previously reported results. The numerical results show that the malaria infection could significantly cause deterioration on the oxygen uptake by red blood cells. The results also suggest that the oxygen uptake by individual stationary RBC/IRBC would not be significantly affected by the neighboring cells provided the separation distance is about the dimension of the cell. Furthermore, it appears that the oxygen uptake by both RBCs and IRBCs is dominated by mass diffusion over the convection although the Peclet number is of the order of unity.