Freshwater transport between the Kara, Laptev, and East-Siberian seas.

The Kara and Laptev seas receive about one half of total freshwater runoff to the Arctic Ocean from the Ob, Yenisei, and Lena rivers. Discharges of these large rivers form freshened surface water masses over wide areas in these seas. These water masses, i.e., the Ob-Yenisei and Lena river plumes, generate an eastward buoyancy boundary current that accounts for the large-scale zonal freshwater transport along the Siberian part in the Arctic Ocean. In this study we investigate spreading of the Ob-Yenisei plume from the Kara Sea to the Laptev Sea through the Vilkitsky Strait and of the Lena plume from the Laptev Sea to the East-Siberian Sea through the Laptev and Sannikov straits during ice-free season. Large horizontal density gradient between freshened plume water and salty ambient sea water is the main driver of these processes, however, their intensity strongly depends on local wind forcing. The Ob-Yenisei plume is spreading to the Laptev Sea in a narrow alongshore current which is induced by strong and long-term southwesterly winds. Under other wind forcing the plume does not reach the Vilkitsky Strait. The Lena plume is almost constantly spreading to the East-Siberian Sea as a large-scale surface water mass which intensity is governed by eastward Ekman transport and is prone to large synoptic variability.

The antitumor effect of magnetic nanodisks and DNA aptamer conjugates.

Here we describe a method of forming large arrays (up to 10(9) pieces) of free magnetic Ni-nanodisks 50 nm thick coated on both sides with layers of 5 nm thick Au. The antitumor effect of the magnetic nickel gold-coated nanodisks and DNA aptamer conjugates was evaluated in vivo and in vitro. Under the influence of rotating magnetic field, the studied nanodisks can cause the death of Ehrlich ascites carcinoma cells.

New composites of betulin esters with arabinogalactan as highly potent anti-cancer agents.

Betulin and its esters are the natural compounds with high in vitro cytotoxicity toward many cancer cells. However, the poor water solubility of these compounds has limited their applications. We prepared new composites of betulin esters using two methods, namely ball-milling of the mixtures of betulin esters with arabinogalactan and preparation of thin films of these mixtures by evaporating the aqueous solutions. These composites revealed higher water solubility as compared with the initial substances without losing the structural integrity and functionality. As a result, the new composites have shown much higher inhibitory effects against different cancer cell lines such as Ehrlich ascites carcinoma cells and lung carcinoma cells (A549) in comparison with the initial substances. The cell viability studies based on Annexin V and Propidium iodide probes have confirmed the high proapoptotic effect of betulin ester derivatives against cancer cells.