Field Effect Transistors for Terahertz Detection: Physics and First Imaging Applications

Resonant frequencies of the two-dimensional plasma in FETs increase with the reduction of the channel dimensions and can reach the THz range for sub-micron gate lengths. Nonlinear properties of the electron plasma in the transistor channel can be used for the detection and mixing of THz frequencies. At cryogenic temperatures resonant and gate voltage tunable detection related to plasma waves resonances is observed. At room temperature, when plasma oscillations are overdamped, the FET can operate as an efficient broadband THz detector. We present the main theoretical and experimental results on THz detection by FETs in the context of their possible application for THz imaging.     

Single molecular switch based on thiol tethered iron(II)clathrochelate on gold

Molecular electronics has been associated with high density nano-electronic devices. Developments of molecular electronic devices were based on reversible switching of molecules between the two conductive states. In this paper, self-assembled monolayers of dodecanethiol (DDT) and thiol tethered iron(II)clathrochelate (IC) have been prepared on gold film. The electrochemical and electronic properties of IC molecules inserted into the dodecanethiol monolayer (IC-DDT SAM) were investigated using voltammetric, electrochemical impedance spectrpscopy (EIS), scanning tunneling microscopy (STM) and cross-wire tunneling measurements. The voltage triggered switching behaviour of IC molecules on mixed SAM was demonstrated. Deposition of polyaniline on the redox sites of IC-DDT SAM using electrochemical polymerization of aniline was performed in order to confirm that this monolayer acts as nano-patterned semiconducting electrode surface.     

Two-dimensional modelling of deposits formation on platen superheaters in pulverized coal boilers

The 1D modeling of deposits formation is not able to describe properly the gas and particles flow in the vicinity of heat transfer tubes in boilers. Especially, the recirculation zones in the down-stream side of tubes are not possible to reproduce by the 1D models. Known applications of the CFD codes to deposition modelling were able to reproduce only the rate of particles deposition on surfaces, while for practical reasons the most important information is the shape and size of deposits, because it enables prediction of heat transfer abatement with boiler operation time. Paper presents 2D modelling of deposits on platen superheaters in pulverized coal boilers. Particularly, the observed in industrial boilers bridging of the tubes spacing was reproduced by the model in which the particle size dependence of the ash sticking probability was proposed. It has been demonstrated that the ash particles size play important role in the deposits growth mechanism.     

Discovery by Minimal Length Encoding: A Case Study in Molecular Evolution

We apply the Minimal Length Encoding Principle to formalize inference about the evolution of macromolecular sequences. The Principle is shown to imply a combination of Weighted Parsimony and Compatibility methods that have long been used by biologists because of their good practical performance. The background assumptions are expressed as an encoding scheme for the observed data and as heuristic rules for selection of diagnostic positions in the sequences. The Principle was applied to discover new subfamilies of Alu sequences, the most numerous family of repetitive DNA sequences in the human genome.     

Über die morphologie von emulsions-PVC

Some aspects of the morphology of emulsion-type PVC are described, particularly: appearance, surface character and size distribution of grain of selected industrial types of PVC. The morphological investigations are related to plastisole viscosity.     

The effect of molybdenum upon the transformations in the matrix of high-speed steels during austenitizing and quenching

Analysis of the transformations during austenitizing and quenching on model alloys imitating, by means of chemical composition, the matrices of the quenched high-speed steels of various relations Mo/W. Analysis of the volume percentage of carbides, grain size, the temperature of the beginning of partial meltings and retained austenite. Results of the model alloy tests in comparison with the high-speed steels of the 18-0-1 and 6-5-2 types.     

Gas sulphonitriding

A new thermochemical treatment, gas sulphonitriding, is described and comparative tests with the Sulfinuz and Tenifer processes are reported. Applications of the new processes are outlined. The tribological properties of gas-sulphonitrided specimens were superior to those of Tenifer-treated specimens and comparable with those of Sulfinuz-treated specimens.