One-electron states and interband optical absorption in single-wall carbon nanotubes

Explicit expressions for the wave functions and dispersion equation for the band p - electrons in single-wall carbon nanotubes are obtained within the method of zero-range potentials. They are then used to investigate the absorption spectrum of polarized light caused by direct interband transitions in isolated nanotubes. It is shown that, at least, under the above approximations, the circular dichroism is absent in chiral nanotubes for the light wave propagating along the tube axis. The results obtained are compared with those calculated in a similar way for a graphite plane.Comment: 16 pages, 8 figures, 1 tabl

Seasonal hydrological and hydrochemical surveys in the Voevoda Bay (Amur Bay, Japan Sea)

Hydrological and hydrochemical surveys were conducted in the Voevoda Bay in May, August, and October, 2011 and February, 2012, in total 140 stations. Free water exchange of the bay with the Amur Bay is observed, with exception of its inner bights Kruglaya and Melkovodnaya. The water exchange is maintained by anticyclonic circulation with the inflow along the southern coast and outflow along the northern coast of the Voyevoda Bay. However, the opposite cyclonic circulation is observed in the Melkovodanaya Bight because of its coastal line patterns and fresh water discharge by the river. Dissolved oxygen content and partial pressure of CO2 in the bay waters are determined mostly by intensive processes of production and destruction of organic matter. There are three main groups of primary producers there, as diatom algae, sea grass Zostera marina , and periphyton. Specific chemical regime is formed in the Melkovodnaya Bight, in particular in winter when primary production depends on the ice cover and is driven by variations of photosynthetically active radiation passed through the ice. Seasonal variability of production-destruction processes intensity is discussed on the data of chemical parameters changes

Electric dipole moments and the search for new physics

Static electric dipole moments of nondegenerate systems probe mass scales for physics beyond the Standard Model well beyond those reached directly at high energy colliders. Discrimination between different physics models, however, requires complementary searches in atomic-molecular-and-optical, nuclear and particle physics. In this report, we discuss the current status and prospects in the near future for a compelling suite of such experiments, along with developments needed in the encompassing theoretical framework.Comment: Contribution to Snowmass 2021; updated with community edits and endorsement

Entropy-Statistical Analysis of the Air Conditioning System of a Passenger Airplane

This article discusses a static mathematical model of the air conditioning system of a passenger aircraft with moisture control. The model was developed to calculate various operation modes of this system, for one of which the entropy-statistical analysis was performed. In the analysis, the main nodes of the circuit are considered, an assessment of their influence on the overall efficiency of the air conditioning system is carried out, as well as the advantages of the given entropy-statistical analysis method for such systems are evaluated. The mathematical model was developed in the Matlab Simulink software package

Production patterns in the estuary of the Razdolnaya River in period of freezing

Light conditions and nutrients supply, as factors of primary production, are considered for the Razdolnaya River estuary in period of freezing (January-March). Water samples were collected at the water surface and at the bottom for measuring of salinity and concentrations of chlorophyll (Chl), phosphate, nitrite, nitrate, ammonium, and silicate. Profiles of water temperature, conductivity, Chl fluorescence, and turbidity were measured in situ by CTD-probe RBR XR-620; besides, vertical attenuation of PAR was measured at each station. The internal estuary (salinity 5 FTU) and high concentration of humine substances (up to 2 mgC/l) in the river waters. The ice cover lowered light intensity in the river water, too. In the zone close to the river bar with salinity 1-25 ‰, Chl concentration was 0.4-1.7 mg/m3 irrespective of salinity. DIN (dissolved inorganic nitrogen) and DISi (dissolved inorganic silicon) had conservative behaviour in this zone, the DISi : DIN ratio was ≈ 0.7-1.1.These features indicate an absence of significant production or destruction of organic matter in the internal estuary. However, intensive removal of dissolved inorganic phosphorus (DIP) (up to 80 %) was observed in this zone, that’s why the extraordinary high DIN : DIP ratio was observed under salinity 5-20 ‰ (up to 200 : 1, though the usual DIN : DIP ratio in the river water is close to Redfild ratio: DIN : DIP = (21-27) : 1). In the external estuary (salinity15-32 ‰), the water became more transparent ( kd = 0.5-0.3 m-1; zeu ≈ 9-15 m) and both chlorophyll concentration and dissolved oxygen content became higher (Chl up to 20 mg/m3, DO up to 500 mM/kg) as the result of high primary production, whereas nutrients concentrations became lower: DIP were completely removed and DIN and DISi retained 10-25 % of their initial values in the river water. The primary production value was evaluated by two ways: on the data of light intensity and on the data of nutrients removal. The light conditions in the internal estuary in February-March corresponded to the value 20-80 mgC/m2d which declines in 6-13 times and 50-100 times (close to zero) under the ice and under the ice with snow, respectively. In the external estuary, the light conditions in March corresponded to the value 300-600 mgC/m2d in the areas without ice and to the value lower in 6-13 times under the ice. The nutrients removal corresponded to the primary production value ≈ 200-400 mgC/m2d in the external estuary, irrespective of ice cover, that is close to the previous estimation by light conditions. So, the primary production in the Razdolnaya River estuary changes in winter in the range from 0 to 500 mgC/m2d, increasing seaward, the ice and snow are the factors of its limitation by light