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The focus of this note is to investigate the hydraulic conductivity behavior of clay mixed with nanomaterials. Two different nanomaterials--namely, gamma-aluminum oxide powder ([gamma]-[Al.sub.2][O.sub.3]) and nano-copper oxide (CuO)--were selected and mixed with clay at different percentages (i.e., 2%, 4%, and 6%). Hydraulic conductivity tests were carried out in a flexible wall permeameter following the ASTM D5084 standard. Mercury intrusion porosimetry (MIP) tests were also carried out to determine the pore-size distribution. At 2% of [gamma]-[Al.sub.2][O.sub.3] and nano-CuO, the hydraulic conductivity of clay decreased 30% and 45%, respectively. As the proportion of the nanomaterial increases, the reduction of hydraulic conductivity becomes less prominent as flow paths devoid of nanomaterials are unlikely. Reduction of hydraulic conductivity is due to the pores of clay being clogged by the nanomaterial. Pore-size distribution curves show that the largest pore size reduced by 20% when clay was mixed with 4% nano-CuO. Key words: nanomaterial, hydraulic conductivity. Le present note a pour objet principal l'etude de la conductivite hydraulique d'un melange d'argile et de nanomateriaux. Deux nanomateriaux differents, soit de la poudre d'oxyde d'aluminium gamma ([gamma]-[Al.sub.2][O.sub.3]) et des nanoparticules d'oxyde de cuivre (nano-CuO), ont ete selectionnes et melanges fi de l'argile dans differentes proportions (c.-a-d. 2, 4 et 6 %). Des essais de conductivite hydraulique ont ete realises a l'aide d'un permeametre a paroi souple en suivant la norme ASTM D5084. Des essais de porosimetrie a intrusion de mercure (PIM) ont ete egalement effectues afin de determiner la distribution de la taille des pores. Pour des pourcentages [gamma]-[Al.sub.2][O.sub.3] et de nano-CuO de 2 %, la conductivite hydraulique de l'argile a respectivement diminue de 30 et 45 %. Lorsque la proportion de nanomateriaux augmente, la reduction de la conductivite hydraulique devient moins importante, car les voies d'ecoulement exemptes de nanomateriaux sont peu probables. La diminution de la conductivite hydraulique est due a l'obstruction des pores de l'argile par les nanomateriaux. Les courbes de distribution de la taille des pores montrent que la taille de pore la plus elevee est reduite de 20 % lorsque l'argile est melangee avec 4 % de nano-CuO. [Traduit par la Redaction] Mots-cles: nanomateriau, conductivite hydraulique., Introduction Hydraulic conductivity is an important engineering property of soil that is essential in irrigation management, seepage analysis, and stability calculations. Its importance is further increasing due to its vital [...]

The effect of laser beam operation mode on transition of grain morphology is analyzed during surface modification of alumina ceramic. The transition in grain morphology is attributed to different levels of undercooling that is a function of cooling rates encountered in two different modes of laser operation.

The studies were conducted to explore the nonequilibrium carrier dynamics in copper selenide nanowires and nanocrystallites in femto- and picosecond time domains. The direct carrier lifetime measurement by means of femto- and picosecond transient techniques showed values in the range of hundreds of picoseconds for copper selenide nanostructures.

We investigated the charging characteristics of alumina in vacuum with varying surface roughness, and the electric field distribution. The charging on the alumina surface in vacuum is, in general, strongly influenced by field electron emission (FEE) and secondary electron emission avalanche (SEEA). We varied the surface roughness and the electric field distribution on the alumina surface in order to control the FEE and the SEEA. Under these conditions, we measured the 2-dimensional distribution of surface charging potential on the alumina surface. From the measurement results, we quantitatively discussed charge polarity and charge density on the surface for various types of electric field distributions. Finally, we successfully propose a concept of a charging control technique on the alumina insulator in vacuum for the improvement of electrical insulation performance on the alumina surface. Index Terms--Charging characteristics, vacuum, surface roughness, alumina insulator, electric field distribution, secondary electron emission avalanche (SEEA).

The effect of surface roughness of insulator on the secondary electron emission (SEE) coefficients was investigated with changing the incident angle of primary electrons. The SEE coefficients were measured using a scanning electron microscope with a single-pulse electron beam (100 pA, 1 ms). As a result, the SEE coefficients increased with the incident angle for smooth surface, while those of rough surface almost did not change with the incident angle. The SEE coefficients of commercial alumina ceramics with three different surface finishes, i.e. as-sintered, as-ground and mirror-finished samples, were also measured before and after annealing treatments. This treatment was carried out in air at 1400 [degrees]C for 1 h. After annealing, the SEE coefficients were higher than those of unannealed samples. This increase is proposed to be due to the defect recoveries as well as neutralizations of charging, which significantly influence the SEE. For relative low purity (95% or less), the SEE coefficients of annealed alumina became lower after mechanical grinding operations and lower again after mirror-finished operations. The SEE coefficients of 99.7% purity alumina were almost unaffected by the mechanical finishes. Index Terms--Alumina ceramic, secondary electron emission, mechanical finish, grinding, polishing, surface roughness, annealing treatment, rf window material.

By reducing the distance between the dielectric end-fittings of a coaxial pulsed corona reactor to values on the order of millimeters, the efficiency of volatile organic compound (VOC) decontamination of atmospheric pressure air could be increased by a factor of seven over that obtained in reactors with electrode lengths in the centimeter range. The increased efficiency is attributed to the increasing effect of surface streamers with increased electron density compared to streamers in the gas space. Packing the discharge gap of the reactor with catalytically active silica gel pellets further increased the energy efficiency of VOCs decontamination by more than 50% over that obtained in the absence of any packing. Silica gel was shown to remove VOC by adsorption until it became saturated. The adsorption provides a tool for handling surplus VOCs under fluctuating input conditions. Destruction of preadsorbed organics on silica gel was also demonstrated. Aluminum oxide pellets showed no catalytic effect on destruction of VOCs under these conditions. Index Terms--Aluminum oxide, benzene, catalysis, hexane, methane, nonthermal plasma, pulsed corona discharges, silica gel, toluene, volatile organic compounds (VOCs).