CFD Model of the Density-Driven Bidirectional Flows through the West Crack Breach in the Great Salt Lake Causeway

Stratified flows and the resulting density-driven currents occur in the natural environment and commonly in saline lakes. In the Great Salt Lake, Utah, USA, the northern and southern portions of the lake are divided by an east-to-west railroad causeway that disrupts natural lake currents and significantly increases salt concentrations in the northern section. To support management efforts focused on addressing rising environmental and economic concerns associated with varied saltwater densities throughout the lake, the causeway was recently modified to include a new breach. The purpose of this new breach is to enhance salt exchange between the northern and southern sections of the lake. Since construction, it typically exhibits a strong density-driven bidirectional flow pattern, but estimating flows and salt exchange has proven to be difficult. To obtain much needed insights into the ability of this hydraulic structure to exchange water and salt between the two sections of the lake, a field campaign coupled with CFD modeling was undertaken. Results from this study indicate that the vertical velocity profile in the breach is sensitive to density differences between flow layers along with breach geometry and water surface elevations. The CFD model was able to accurately represent the bidirectional flows through the breach and provides for improved estimates of water and salt exchanges between the north and south sections of the lake.

Secondary hyperaldosteronism and medullary nephrocalcinosis caused by self-administered and uncontrolled laxative use in an adolescent patient

Secondary hyperaldosteronism is respondent aldosterone secretion increase, occurring due to some diseases or drug use. It may be accompanied by normal arterial pressure with/without water retention or arterial hypertension without water retention. Secondary hyperaldosteronism without arterial hypertension and without water retention is usually caused by the use of laxative and diuretic drugs. This condition is characterized by the lack of salt wasting symptoms, presence of myalgia and muscle weakness resulting from hypokalemia, calcium oxalate crystalluria and sonographic signs of medullary nephrocalcinosis. Such characteristics of water-salt exchange and presence of nephrocalcinosis in combination with hypercalciuria are defined as Bartter-like syndrome. Peculiarity of the given clinical case is determined not by a diagnostic difficulty of secondary hyperaldosteronism but concealment of long term self-administered use of laxatives 2 years without medical indications in a female patient, resulting in medullary nephrocalcinosis. A well-informed patient may endanger medical practice, because it is impossible to foresee everything including the uncontrolled self-administered drug use leading to the undesirable consequences.

ARGO-BASED STUDY OF WATER, HEAT, AND SALT EXCHANGE BETWEEN ATLANTIC, NORDIC SEAS, AND ARCTIC OCEAN

The annual mean temperature, salinity, density, and velocity fields for the region of the Nordic Seas were calculated and studied using the Argo-based model for the period of 2005–2014. The mass, heat, and salt transports through the Denmark and Fram Straits, and through the sections separating the Nordic Seas from the Atlantic Ocean and Barents Sea were studied on the climatological, annual, and seasonal time scales. The calculated transports are in good agreement with the previous estimations based on direct velocity measurements. Comparative analysis of transports variations and the North Atlantic Oscillation (NAO) index shows a well pronounced correlation between them. The positive heat budget of the studied region for the period of 2005–2014 was estimated as 92±56 TW.

Design of FeBi nanoparticles for imaging applications

A variety of imaging technologies are now routinely used in the medical field, their use being continuously enlarged through the development of contrast agents. Recently nanoparticles (NPs) proved efficient to improve imaging in vivo by increasing contrast and targeting capabilities. The current trend is now focused on the development of dual contrast agents combining two or more functionalities on the same NP. Motivated by this new challenge we developed FeBi NPs as new nanomaterials with potential application as a contrast agent for MRI and CT imaging. In addition to the well-known use of iron in the development MRI contrast agents, we chose Bi as a CT imaging agent rather than the more documented gold, because it possesses a larger X-ray attenuation coefficient and is much less expensive. Two sets of NPs, with sizes around 150 nm and 14 nm, were synthesized using organometallic approaches. In both cases, the NPs are spherical, and contain distinct domains of Fe and Bi, with the surface being enriched with Fe, and a hydrophobic coating. This coating differs from one sample to the other: the surfaces of the 150 nm large NPs are coated by amine ligands, while those of the 14 nm large NPs are coated by a mixture of an amine and its hydrochloride salt. Exchange of the surface ligands to afford water soluble NPs has been attempted. We show that only the larger NPs could be functionalized with water soluble ligands, which is in agreement with the lability of their initial surface coating. Colloidal aqueous solutions of FeBi NPs with glycoPEG ligands have been obtained.