Spatial coherence in strongly scattering media

We study the spatial coherence of an optical beam in a strongly scattering medium confined in a slab geometry. Using the radiative transfer equation, we study numerically the behavior of the transverse spatial coherence length in the different transport regimes. Transitions from the ballistic to the diffusive regimes are clearly identified.     

Total Oxidation of Dichloromethane Over Metal Oxide Catalysts

Three different transition metals (V, Mn and Cu) supported on TiO₂, MgO and CeO₂, were investigated for their performances in dichloromethane oxidation (500 ppm, 704,867 h^?1) in moist conditions as a model reaction for the destruction of chlorinated volatile organic compounds. The catalysts were prepared by sol–gel method followed by wet impregnation of V, Mn or Cu precursors. The activities were evaluated in the temperature range from 100 to 500 °C with 5 °C min^?1 temperature rise. The orders of activity and selectivity to HCl of the catalysts is CuTi > VMg > CuCe > CuMg. A correlation between acidic properties of support and performances was observed as the activity of copper catalysts followed the acidity order of supports.     

Dynamics of inertial dewetting

The dynamics of fast dewetting is considered in both unidirectional and axisymmetric dewetting cases. The analysis provides the front and dewetting velocities along with the wave speed (Froude number larger than 1) based on the momentum and continuity equations. The model does not require any fitting parameter. In the unidirectional case, the present model results are direct, while in the axisymmetric case, a simple trial-and-error procedure is required. Culick’s law (derived for the rupture of soap films and extended to unidirectional fast dewetting velocity by other investigators) is found to be a limiting case for both the dewetting and front velocities at small values of the film thickness for both unidirectional and axisymmetric dewetting geometries. The proposed model results show favorable agreement with published experimental front velocity data at large values of the film thickness.     

Effect of surface roughness and complex indices of refraction on polarized thermal emission

We present a series of measurements characterizing the dependence of polarized thermal emission on surface roughness. In particular, we measure the spectrally resolved degree of linear polarization (DOLP) for a series of roughened borosilicate (Pyrex) glass substrates as a function of the roughness parameter Ra, the root-mean-square slope distribution, and observation angle theta. Also measured are a series of smooth glass substrates coated with two particular polymers of interest, i.e., a common commercially available Krylon paint and a chemical-agent-resistant coating paint. The DOLP is measured over a 4-13 microm wave band by using a modified Fourier transform IR spectrometer in which a wire-grid polarizer and a quarter-wave Fresnel rhomb are used in conjunction to measure all four Stokes parameters. In addition, we show an enhanced DOLP due to anomalous dispersion exhibited by the surface material.     

Perspectives for 10 terabits/in2 magnetic recording

Magnetic recording technology has come a long way, since the introduction of the first hard disk drives (HDD) in 1956. The areal density has grown by a factor of 200 million times and the HDD has stayed as a main candidate for mass storage of information. In order to maintain its lead over other competing technologies, HDD industry continues to invent several technologies. Having introduced perpendicular recording technology in the last 5 years, the industry is looking at introducing bit-patterned media or heat-assisted magnetic recording in the next five years. The researchers--looking at a longer term--are investigating 10 Tbits/in2 as the next major milestone. The issues and probable candidates for 10 Tbits/in2 magnetic recording technology are described from a material perspective.     

A Robust Approach for Locating and Assessing Mechanical Faults in an Actual Transformer Winding Using the State Space of Its Lumped Equivalent Model

Russian Journal of Nondestructive Testing - Transfer function and state-space model are two powerful complementary tools have been used to monitoring the physical system. These two ways can be very...     

Methyl Ester ofp-Coumaric Acid: A Phytoalexin-Like Compound from Long English Cucumber Leaves

Methanolic extracts from long English cucumber leaves were fractionated and tested for their fungitoxicity by direct bioassay againstCladosporium cucumerinum on TLC plates. After separation by several preparative TLCs and flash chromatography and purification through reverse-phase HPLC, a crystalline compound possessing antifungal properties was isolated and identified asp-coumaric acid methyl ester. This antifungal compound was found to increase following infection and treatment with Milsana^®, which could explain in part the prophylactic properties of the natural inducer. As such,p-coumaric acid methyl ester is the first identified compound to be associated with phytoalexin-like behavior in cucumber.