Development of a rotating ring-disc electrode for high temperature studies in cryolite-based melts

A compact rotating ring-disc electrode incorporating a molybdenum disc, gold ring and boron nitride insulator has been designed, constructed and evaluated in molten cryolite-based electrolytes at temperatures up to 1000°C and rotation rates between 0 and 2000 rpm. The electrode design is extremely versatile and relatively maintenance free, with no visible evidence of melt leakage at the ring-insulator and disc-insulator interfaces. The operating performance of the gold-molybdenum rotating ring-disc electrode was evaluated from collection efficiency measurements based on the dissolution of the disc surface and subsequent detection of soluble species transported to the ring. The observed collection efficiency was less than the theoretical value determined from the geometry of the electrode, primarily because of noncoplanarity of the electrode surface at the working temperature. The results confirm that the electrode should be useful for mechanistic studies in high temperature molten fluoride electrolytes.     

Electrocatalytic activation of Ni electrode for hydrogen production by electrodeposition of Co and V species

Hydrogen is considered to be the most promising candidate as a future energy carrier. One of the most used technologies for the electrolytic hydrogen production is alkaline water electrolysis. Electrode materials used in alkaline water electrolysis are mainly made from Ni or Ni-based alloys due to their desirable mechanical and chemical stability in hot and alkaline solution. Considerable research effort has been conducted on enhancement of electrocatalytic activity of Ni electrodes.     

Building Many-Core Processor-to-DRAM Networks with Monolithic CMOS Silicon Photonics

Silicon photonics is a promising technology for addressing memory bandwidth limitations in future many-core processors. This article first introduces a new monolithic silicon-photonic technology, which uses a standard bulk CMOS process to reduce costs and improve energy efficiency, and then explores the logical and physical implications of leveraging this technology in processor-to-memory networks.     

Hybrid Radio Resource Management with Co-scheduling for Relay Extended OFDMA Networks

Wireless Personal Communications - In orthogonal frequency division multiple access networks buffer aided non-transparent in-band half duplex decode and forward relay nodes aim to improve coverage...     

Potential Barrier of (Zn,Nb)SnO2‐Films Induced by Microwave Thermal Diffusion of Cr3+ for Low‐Voltage Varistor

The effect of Cr³⁺ on the electrical properties of SnO₂‐based films deposited by electrophoresis on Si/Pt substrate was considered. The films were sintered in a microwave oven at 1000°C/40 min and then the surface was modified with deposition of Cr³⁺ ions by electrophoresis. The diffusion of Cr³⁺ contributes to the modification of the potential barrier formed on the grain boundary improving the electrical properties due to electron acceptor species adsorption on the grain boundary. The influence on the properties of grain boundary was verified by I versus V characterization in as a function of temperature. The films showed nonlinear coefficient over 9, potential barrier height over 0.5 eV and resistivity greater than 10⁷ Ω·cm. 4 samples were prepared at same conditions and presented similar electrical behavior, showing the efficiency of technique on reproducibility to varistor properties control. Thereby the nonlinear coefficient increases while decreasing the conductivity of the system is noticed.     

Preparation of MEMO silane-coated SiO2 nanoparticles under high pressure of carbon dioxide and ethanol

The objective of this study is to investigate and compare methods of nanosilica coating with γ-methacryloxypropyltrimethoxy (MEMO) silane using supercritical carbon dioxide and carbon dioxide-ethanol mixture. Characterization of grafted silane coupling agent on the nanosilica surface was performed by the infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). The d₅₀ value and particle size distribution were determined by laser particle size analyzer (PSA). The operating parameters of silanization process at 40 °C, such as the silica/silane weight ratio, the presence of ethanol, and the pressure, were found to be important for the successful coating of silica particles with minimum agglomeration. The results indicate that presence of ethanol in high-pressure carbon dioxide plays an important role in achieving successful deagglomeration of coated nanoparticles. Dynamic mechanical analysis (DMA) and scanning electron microscopy (SEM) revealed that dispersion of the silica particles in the PMMA matrix and interfacial adhesion between silica particles and polymer matrix were enhanced, when silica nanoparticles treated with silane under high pressure of carbon dioxide and ethanol were used for the nanocomposite preparation.     

Some Experiments and Directions in Molecular Computing and Robotics

In this review I present a chemist’s perspective on molecular computing and molecular robotics. I start with nucleic acid catalysts and then show how the application of some concepts from computer sciences and macroscopic robotics enable engineering of interesting behaviors in molecular systems.     

Carbon monoxide oxidation on Au(1 1 1) surface decorated by spontaneously deposited Pt

Platinum is deposited spontaneously on Au(1 1 1) surface from 1 mM H₂PtCl₆ + 1 M HClO₄ solution using multiple deposition procedure. X-ray photoelectron spectroscopy (XPS) analysis has shown that after immersion into the Pt containing solution and rinsing with water, Pt(OH)₂ resides on the Au(1 1 1) substrate. Consecutive depositions as well as in situ scanning tunneling microscopy (STM) and electrochemical measurements are performed on previously electrochemically reduced Pt/Au(1 1 1) surfaces. Only homogeneous distribution of thus deposited Pt islands is observed by in situ STM. With subsequent depositions, the width of deposited Pt islands increases, but stays lower than 10 nm, while a significant increase of Pt islands height is observed, leading to moderate increase of the coverage. Cyclic voltammetry (CV) profiles of obtained Pt/Au(1 1 1) surfaces, and CO stripping curves are recorded in 0.5 M H₂SO₄ solution. CO oxidation takes place only at higher potentials shifting negatively with increasing coverage. This is discussed with respect to Pt islands width and height distributions and to the influence of the Au(1 1 1) substrate surface.     

Evaluation of optimal bandwidth in optical FSK system influenced bylaser phase noise

In this paper, an optical frequency shift keying (FSK) system with TFS (two-filter structure), also known as dual-filter FSK, is observed in the presence of laser phase noise. Sensitivity of the receiver is shown as a function of intermediate frequency (IF) bandwidth and a bandwidth of the low-pass postdetection filter. It is shown that there is an optimal pair of bandwidths which minimizes required sensitivity; a few figures for different amounts of phase noise are given. The results in this paper are based on truncated Taylor expansion method and a method based on complex analysis is used to evaluate the integrals involved