A new method for sampling and chemical analysis of alphacypermethrin in workplace air has been described. Air samples were taken using a glass tube filled with silica gel with chemically bounded octadecyl phase. Chromatographic determinations were conducted using an HP-5 capillary column (10 m x 0.53 mm) and an electron-capture detector. Alphacypermethrin recovery was 100.15%. The calculated de...

where R is the radius of the mica cylinders used for the measurement, Do=1.2 nm and Co=30 mN/m. Hydrophobic forces have also been observed with other cationic surfactants, such as dodecylammoniumhydrochloride (DAHCl), octadecyl-ammoniumhydrochloride (OAHCl) and dihexadecyl-dimethyl ammonium acetate (DHDAA), in equilibrium with mica and silica surfaces (2,3). The Co and Do values obtained with t...

A conflict-free coloring for a given set of disks is a coloring of the disks such that for any point p on the plane there is a disk among the disks covering p having a color different from that of the rest of the disks that covers p. In the dynamic offline setting, a sequence of disks is given, we have to color the disks one-by-one according to the order of the sequence and maintain the conflic...

solid phase extraction (spe) cartridge embedded with octadecyl c18 chain bounded to silica particles were used for the isolation and trace enrichment of pesticides from water samples collected from cotton, rice growing and municipal areas. the eluents were analyzed with high performance liquid chromatography (hplc) using methanol (100%) as mobiles phase at different uv-visible wavelengths. ddt ...

We investigate the evolution of ∼ 3 Myr-old MIPS-detected circumstellar disks in IC 348 that may be in an intermediate stage between primordial, optically-thick disks of gas/dust and debris disks characteristic of the final stages of planet formation. We demonstrate that these anemic disks are not a homogenous class of objects corresponding to a unique evolutionary state. Rather, such disks aro...

A procedure for separation and preconcentration of trace amounts of Zn(II) from aqueous media is proposed. The procedure is based on the adsorption of Zn2+ on octadecyl bonded silica membrane disk modified with N,N’-disalicylidene-1,2-phenylendiamine at pH 7. The retained zinc ions were then stripped from the disk with a minimal amount of 1.5 mol L-1 hydrochloric acid solution as eluent, and de...

By using event-driven molecular dynamics simulation, we investigate effects of varying the area fraction of the smaller component on structure, compressibility factor, and dynamics of the highly size-asymmetric binary hard-disk liquids. We find that the static pair correlations of the large disks are only weakly perturbed by adding small disks. The higher-order static correlations of the large ...

We study local stability of self-gravitating fluid and stellar disk in the context of modified gravity theories which predict a Yukawa-like term in the gravitational potential of a point mass. We investigate the effect of such a Yukawa-like term on the dynamics of self-gravitating disks. More specifically, we investigate the consequences of the presence of this term for the local stability of t...