Drivers and extent of surface water occurrence in the Selenga River Delta, Russia.

Study region: Selenga River Delta (SRD), Russia. Study focus: How is water occurrence changing in the SRD, and what are the hydroclimatic drivers behind these changes? The presence of water on the surface in river deltas is governed by land use, geomorphology, and the flux of water to and from the Delta. We trained an accurate image classification of the Landsat satellite imagery during the last 33 years to quantify surface water occurrence and its changes in the SRD. After comparing our estimations with global-scale datasets, we determined the hydrological drivers of these changes. New hydrological insights for the region: We find mild decreases in water occurrence in 51% of the SRD's surface area from 1987-2002 to 2003-2020. Water occurrence in the most affected areas decreased by 20% and in the most water-gaining areas increased by 10%. We find a significant relationship between water occurrence and runoff (R2 = 0.56) that does not exist between water occurrence and suspended sediment concentration (SSC), Lake Baikal's water level, and potential evapotranspiration. The time series of water occurrence follows the peaks in the runoff but not its long-term trend. However, the extremes in SSC do not influence surface water occurrence (R2 < 0.1), although their long-term trends are similar. Contrary to expected, we find that the Delta has a relatively stable long-term water availability for the time being.

Formation and stability of water clusters at the molybdenum disulfide interface: a molecular dynamics simulation investigation.

In this work structural properties and dynamic behavior of a water nano droplet on the molybdenum disulfide were considered. The simulation results show that water molecules form polygon clusters on the interface, and most of which are hexagonal. Structures of water clusters at the interface are seen in two forms of curved and flattened polygons, which result in the formation of hydrogen bonds between and in the adjacent layers, respectively. Most of the clusters have circular flattened structures. Calculations of the lifetime of hydrogen bonds of water molecules at the interface also show that hydrogen bonds between water molecules at the interface have a low stability. This leads to the permanent formation and breaking down of hydrogen bonds of water molecules which can cause movement of water molecules and, consequently, the displacement of the center of mass and droplet motion. Considering the changes in the center of mass of a water droplet at the MoS2 interface display, the water droplet has a significant spontaneous motion.

Structural and dynamical characterization of water on the Au (100) and graphene surfaces: A molecular dynamics simulation approach.

The positioning, adsorption, and movement of water on substrates is dependent upon the chemical nature and arrangement of the atoms of the surface. Therefore the behavior of water molecules on a substrate is a reflection of properties of the surface. Based on this premise, graphene and gold substrates were chosen to study this subject from a molecular perspective. In this work, the structural and dynamical behaviors of a water nanodroplet on Au (100) and the graphene interfaces have been studied by molecular dynamics simulation. The results have shown how the structural and dynamical behaviors of water molecules at the interface reflect the characteristics of these surfaces. The results have demonstrated that residence time and hydrogen bonds' lifetime at the water-Au (100) interface are bigger than at the water-graphene interface. Energy contour map analysis indicates a more uniform surface energy on graphene than on the gold surface. The obtained results illustrate that water clusters on gold and graphene form tetramer and hexamer structures, respectively. Furthermore, the water molecules are more ordered on the gold surface than on graphene. The study of hydrogen bonds showed that the order, stability, and the number of hydrogen bonds is higher on the gold surface. The positioning pattern of water molecules is also similar to the arrangement of gold atoms while no regularity was observed on graphene. The study of dynamical behavior of water molecules revealed that the movement of water on gold is much less than on graphene which is in agreement with the strong water-gold interaction in comparison to the water-graphene interaction.

Ashkan Ghasemi Moghaddam1, Mozafar Razavi Seyed1, Mehrshad Rasouli1, Sajad Hosseinzade1, Mohammad Mehdi Darvishi2, Arash Rakhshanpour3, Mohammad Taghi Rahimi4,5

Objective:To survey the prevalence of cattle ticks in Nur County and prepare a list of tick fauna in this district. Methods: This investigation was carried out on 150 head of cattle ticks of rural areas of Nur city which is located in Mazandaran province during spring and summer seasons of 2011. The collected ticks were identified using light microscope and available systematic keys. Results:A total number of 1 563 ticks were isolated from examined cattle and their genus and numbers including:Ixodes ricinus 51%(111 male and 691 female) and Boophilus annulatus 49%(83 male and 678 female), respectively. Conclusions:Results of the current investigation indicate the presence of two species of acarine ectoparasites which have potential health risk Ixodes ricinus and Boophilus annulatus. More studies are required to increase our data concerning ticks and other ectopreasites of ruminants in other areas of Mazandaran province and should be noted to their ability in transmission of infectious agents.