Volt-Watt Sensitivity of Semimetal <Emphasis Type="Italic">BiSb</Emphasis> Film Thermocouple Sensors in the 8 mm Wavelength Range

The paper considers the experimental and analytical data on volt-watt characteristics of metal-semimetal BiSb film point contacts in 8 millimeter wavelength range. Analytical expressions have been obtained for the volt-watt sensitivity and the resistance of the metal-semimetal BiSb film point contacts. A thermoelectric millimeter wave range detector has been designed on the basis of the sensors; the performance is illustrated by experimentally determined volt-watt relations.     

Cross-correlation frequency-resolved optical gating for studying ultrashort-pulse nonlinear dynamics in arbitrary fibers

We describe a cross-correlation frequency-resolved optical-gating system specifically designed for studying nonlinear pulse-propagation dynamics in fibers of arbitrary length at telecommunication wavelengths. The formation of optical solitons and the appearance of temporal phase slips are observed in 100 m of fiber. The wide phase-matching bandwidth and high sensitivity of this system allow us to visualize femtosecond-pulse evolution in a range of linear and nonlinear propagation regimes.     

Mode propagation in optical nanowaveguides with dielectric cores and surrounding metal layers

The mode spectrum in an optical nanowaveguide consisting of a dielectric-core layer surrounded by two identical metal layers is investigated. A simple model based on mode matching to predict the properties of mode propagation in such optical nanowaveguides is proposed. It is shown that quasi-TM00 and quasi-TM10 modes supported by an optical microstrip line do not have a cutoff frequency, regardless of the size of the metal strips, the thickness of the dielectric slab, and the cross-sectional shape. The transverse size of the TM00 mode supported by a nanosized microstrip line was found to be approximately equal to the transverse dimension of the microstrip line. In closed rectangular and elliptical nanowaveguides, i.e., in which all dielectric surfaces are covered with metal films, the cross-sectional shape of the waveguide should be stretched along one side to produce propagation conditions for the fundamental mode.     

A method for measuring tissue-equivalent dose using a pin diode and activation foil in epithermal neutron beams with EN < 100 keV

Silicon (Si) pin diodes can be used for neutron dosimetry by observing the change in forward bias voltage caused by neutron induced displacement damage in the diode junction. Pin diode energy response depends on Si displacement damage KERMA (K(Si)). It is hypothesised that tissue-equivalent (TE) neutron dose could be expressed as a linear combination of K(Si) and foil activation terms. Monte Carlo simulations (MCNP) of parallel monoenergetic neutron beams incident on a cylindrical TE phantom were used to calculate TE dose, K(Si) and Au, Cu and Mn foil activations along the central axis of the phantom. For spectra with neutron energies <100 keV, it is possible to estimate the TE kerma based on silicon damage kerma and Cu or Mn foil measurements. More accurate estimates are possible for spectra where the maximum neutron energy does not exceed 30 keV.     

Calibration of X-Ray Diffraction Instruments for Residual-Stress Measurement

Russian Engineering Research - The deficiencies of existing standard iron and nickel samples for calibration by means of X-ray diffraction are noted. These standards cannot be used in calibration...     

Application of the contact potential difference technique for on-line rubbing surface monitoring (review)

The Kelvin technique for measuring contact potential differences has been adapted for continuous non-destructive monitoring of changes in the electron work function of a rubbing surface. The method can be used to investigate tribological materials for a wide range of conditions, including changes in load, sliding speed, and environment, with or without lubrication. It relies on the sensitivity of the work function to the various events which accompany friction, e.g., plastic deformation, creation of new surface material, adsorption, oxidation, phase changes and redistribution of alloy components. At present, this is the only method which is sensitive to both surface and near-surface defects and permits study of one of the two interacting surfaces during sliding. Current work emphasizes two aspects of sliding behavior: (1) critical points with respect to changes in normal load, with relevance to materials selection and optimization, and (2) the kinetics of friction processes, including periodic changes which may be related to those in fatigue. This revised version was published online in June 2006 with corrections to the Cover Date.     

Iron-bearing silicon nitride composite materials made from powders milled in a planetary mill

The effect of milling in an AGO-3 centrifugal planetary activator with steel milling balls on the properties of Si₃N₄ powders, the conditions of sintering, and the phase composition, structure, and properties of composite materials based on them is described. The possibility of and the process conditions for obtaining dense shock-resistant composite materials based on preliminarily milled β-Si₃N₄ (SHS) powder and additives that activate the sintering and consist of AlN, Al₂O₃, and ZrO₂ powders are studied. It is established that in the sintered materials the presence of FeSi formed due to the interaction of Si₃N₄ and Fe that appears in the milling process does not worsen appreciably the thermomechanical properties of the composite materials.     

Molecular plasmonics with tunable exciton-plasmon coupling strength in J-aggregate hybridized Au nanorod assemblies

Controlling coherent electromagnetic interactions in molecular systems is a problem of both fundamental interest and important applicative potential in the development of photonic and opto-electronic devices. The strength of these interactions determines both the absorption and emission properties of molecules coupled to nanostructures, effectively governing the optical properties of such a composite metamaterial. Here we report on the observation of strong coupling between a plasmon supported by an assembly of oriented gold nanorods (ANR) and a molecular exciton. We show that the coupling is easily engineered and is deterministic as both spatial and spectral overlap between the plasmonic structure and molecular aggregates are controlled. We think that these results in conjunction with the flexible geometry of the ANR are of potential significance to the development of plasmonic molecular devices.     

Polyphenols Fingerprinting in Olive Oils Through Maximum-Quantum NMR Spectroscopy

An NMR protocol based on multiple-quantum spectroscopy is presented for an analytical screening of polyphenols in olive oils. Three Italian olive oils with different total polyphenols content were used as study case. A total of 24 compounds were identified as follows: 1 polyphenol in the 5Q–1Q, 15 more in the 4Q–1Q, and 8 components in the 3Q–1Q spectra, consisting of organic phenols, secoiridoids, lignans, and flavonols. In the three Italian olive oils investigated here, the polyphenols profile turned out to be significantly different, with specific characteristics going beyond simple considerations based on the total polyphenol content. The approach presented here can be easily extended for rapid qualitative and semi-quantitative screening of the polyphenol composition in many food products.