Singing behavior of fin whales in the Davis Strait with implications for mating, migration and foraging

Most baleen whales undertake migrations between low-latitude breeding grounds and high-latitude feeding grounds. Though little is known about the timing of their migration from the Arctic, fin whales are assumed to undertake a similar migratory pattern. To address questions about habitat use and migrations, the acoustic activity of fin whales in Davis Strait, between Greenland and Canada, was monitored continuously for two years using three bottom-moored acoustic recorders. The acoustic power in the fin whale call frequencies peaked in November-December, showing that fin whales are present in Davis Strait much later in the year than previously expected. The closely timed peaks in song activity and conception time imply that not all fin whales migrate south to mate, but rather start mating at high latitudes rather than or before migrating. Singing activity was strongly linked to daylight hours, suggesting that fin whales might feed during the few daylight hours of the late fall and early Arctic winter. A negative correlation between the advancing sea ice front and power in fin whale frequencies indicates that future changes in sea ice conditions from global warming might change the distribution and migratory patterns of fin whales near the poles.     

焙烧硼钠钙石在高固液比氯化铵溶液中的溶解动力学

Boron is available in the form of metal borates, especially of sodium and calcium, in nature[1]. The production of boron compounds has substantially increased recently due to increasing uses of these compounds in nuclear technology, in rocket engines as f…     

Jahn-Teller distortions and the supershell effect in metal nanowires

A stability analysis of metal nanowires shows that a Jahn-Teller deformation breaking cylindrical symmetry can be energetically favorable, leading to stable nanowires with elliptic cross sections. The sequence of stable cylindrical and elliptical nanowires allows for a consistent interpretation of experimental conductance histograms for alkali metals, including both the electronic shell and supershell structures. It is predicted that for gold, elliptical nanowires are even more likely to form since their eccentricity is smaller than for alkali metals. The existence of certain metastable superdeformed nanowires is also predicted.     

The Effect of the Removal of One Product on the Optimum Yield in an Equilibrium Process

Abstract

Except for a first-order dissociation, complete conversion is not possible in an equilibrium process no matter how efficient the removal of a byproduct may be. In a first-order dissociation process, complete reaction is only possible when the ratio of the rate constants of the forward to the backward reaction is greater than unity.     

Measurement of mean ionic activity coefficients for tetra-n-butyl ammonium salts of PF 6? and [B(C6F5)4]? in tetrahydrofuran and acetonitrile

Osmotic coefficients were measured for tetra-n-butylammonium hexafluorophosphate (TBA PF₆) and tetra-n-butylammonium tetrakis(pentafluorophenyl)borate (TBABARF) in tetrahydrofuran and in acetonitrile. These osmotic coefficients were fit using equations first derived by Pitzer. Mean ionic activity coefficients were determined using the integrated form of the Pitzer equations. Densities were measured for each of the solutions and the results were used to convert mean ionic activity coefficients on the molal scale to the molar scale. Remarkably, over concentrations ranging from 0.1 to 1.0 m in acetonitrile, the behavior of TBABARF is consistent with the simple Debye-Hückel equation. Published in Russian in Elektrokhimiya, 2008, Vol. 44, No. 1, pp. 66–73. The text was submitted by the authors in English.