Monte Carlo simulation of cluster kinetics in three-dimensional Ising model

Simulations in lattices of size 100³ at the critical point of the three-dimensional Glauber kinetic Ising model indicate that the 1935 Becker-Doring equation no longer works there: The growth rates decay in time. These conclusions confirm those in two dimensions.     

A note on the thermodynamics of dimanganese and dirhenium decacarbonyls

The results of low temperature heat capacity studies on Mn₂(CO)₁₀(s) and Re₂(CO)₁₀(s) are compared with literature reports. It is shown that the values of vaporization enthalpies and entropies correspond with those of the low temperature stable phase.     

Übergangsmetall-thioketen-komplexe: VII. Erzeugung eines vinyliden-liganden aus einem thioketen durch schwefelabspaltung

The thioketene iron cluster (CH₃)₄C₆H₆CS(PPh₃)₂(CO)₄Fe₂S (I) reacts with thioketene in excess quantitatively to a vinylidene complex, as confirmed by X-ray analysis.     

A natural 15N approach to determine the biological fixation of atmospheric nitrogen by biological soil crusts of the Negev Desert

Biological soil crusts are important cryptogamic communities covering the sand dunes of the north-western Negev. The biological crusts contain cyanobacteria and other free-living N(2)-fixing bacteria and are hence able to fix atmospheric nitrogen (N). This is why they are considered to be one of the main N input pathways into the desert ecosystem. However, up to now, in situ determinations of the N(2) fixation in the field are not known to have been carried out. We examined the natural (15)N method to determine the biological N(2) fixation by these soil crusts under field conditions. This novel natural (15)N method uses the lichen Squamarina with symbiotic green algae--which are unable to fix N(2)--as a reference in order to determine N(2) fixation. Depending on the sampling location and year, the relative biological fixation of atmospheric nitrogen was estimated at 84-91% of the total N content of the biological soil crust. The cyanobacteria-containing soil lichen Collema had a fixation rate of about 88%. These fixation rates were used to derive an absolute atmospheric N input of 10-41 kg N ha(-1) year(-1). These values are reasonable results for the fixation of atmospheric N(2) by the biological crusts and cyanolichens and are in agreement with other comparable lab investigations. As far as we are aware, the results presented are the first to have been obtained from in situ field measurements, albeit only one location of the Negev with a small number of samples was investigated.