Existing methods based on the diffusion theory have been extended to determine the sediment concentration distribution for large concentrations of sand. The modifications for volumetric concentrations ranging from 4 to 20% include decreased fall velocity, and increased viscosity and specific weight of the suspension. The sediment concentration profiles are sensitive to the velocity profiles and...

BACKGROUND Beach sand can harbor fecal indicator organisms and pathogens, but enteric illness risk associated with sand contact remains unclear. METHODS In 2007, visitors at 2 recreational marine beaches were asked on the day of their visit about sand contact. Ten to 12 days later, participants answered questions about health symptoms since the visit. F+ coliphage, Enterococcus, Bacteroidales...

Previous research has shown that the temperature of underlying permafrost decreases after the ground surface is covered with sand. No significant conclusions have yet been drawn that explain why this happens, because the heat transfer mechanism effects of the sand layer on the underlying permafrost remain unclear. These mechanisms were studied in the present work. We found that the upward short...

In the evolution processes of wind blown sand movement and aeolian geomorphology, it always contains some complex behaviors, for example, the nonlinear character of turbulence and attractors, the stochastic character of wind gust, liftoff and movement of sand, the interaction among wind field, sand movement, electric field in wind blown sand flux and thermal diffusion, multi-scale character fro...

Straw checkerboard barrier (SCB) is the most representative antidesertification measure and plays a significant role in antidesertification projects. Large-eddy simulation and discrete-particle tracing were used to numerically simulate the wind sand movement inside the straw checkerboard barrier (SCB), study the movement characteristics of sand particles, find the transverse velocities of sand ...

The measurements of activity concentration of uranium, thorim and potassium were carried out in radiation shielding bricks, granites, soil, hematite, bricks, and sand by using a high resolution high purity Germanium (HPGe) gamma-ray spectrometer system. The activity concentrations of uranium, thorium and potassium contents are 80 ± 5 Bq/kg, 103±10 Bq/kg and 1014±15 Bq/kg, respectively in radiat...

Evolutionary theory predicts that virulence of parasites for mobile vector insects will be low for natural parasite-host associations that have coevolved. I determined virulence of the malaria parasite of lizards, Plasmodium mexicanum, for its vectors, two species of sand fly (Diptera: Psychodidae), Lutzomyia vexator (Coquillett 1907) and Lutzomyia stewarti (Mangabeira Fo & Galindo 1944), by me...

We study the evolution of a one-dimensional pile, empty at rst, which receives a grain in its rst stack at each iteration. The nal position of grains is singular: grains are sorted according to their parity. They are sorted on trapezoidal areas alternating on both sides of a diagonal line of slope p 2. This is explained and proved by means of a local study. Each generated pile, encoded in heigh...

In this study, transport behaviors of graphene oxide (GO) in saturated uncoated (i.e., clean sand) and goethite-coated sand porous media were examined as a function the phosphate. We found that phosphate enhanced GO over wide range solution chemistry pH 5.0–9.0 presence 10 mmol/L Na+ or 0.5 Ca2+). The results mainly ascribed to increase electrostatic repulsion between nanoparticles media. Meanw...