Candidates For Experimental Investigation Research Articles

Silicene-terminated surface of calcium and strontium disilicides: properties and comparison with bulk structures by computational methods

The bulk and surface structures of calcium and strontium disilicides are investigated by computational methods using density functional theory. The investigated structures are R6, R3 and P1-CaSi2 and P1-SrSi2. The investigated properties are the cleavage energy at the silicene sheet, buckling of the bulk and surface silicene layers, charge transfer from calcium to silicon, band structure of bulk and surface-terminated structures and adsorption energies on H atoms and H2 molecules on the silicene-terminated surface of the R3 phase. The cleavage energy at the silicene surface is low in all cases. Structures P1-CaSi2 and R3-CaSi2 contain silicene sheets with different coordination to Ca, while R6-CaSi2 contains both types of the sheets. It is shown that the properties of the two types of silicene-like sheets in R6-CaSi2 are similar to those of the corresponding sheets in P1-CaSi2 and R3-CaSi2, and the thermodynamically stable R6 phase is a good candidate for experimental investigation of silicene-terminated surface in calcium disilicide.

Cervid herpesvirus 2 and not Moraxella bovoculi caused keratoconjunctivitis in experimentally inoculated semi-domesticated Eurasian tundra reindeer

BackgroundInfectious keratoconjunctivitis (IKC) is a transmissible disease in semi-domesticated Eurasian reindeer (Rangifer tarandus tarandus). It is regarded as multifactorial and a single causative pathogen has not yet been identified. From clinical outbreaks we have previously identified Cervid herpesvirus 2 (CvHV2) and Moraxella bovoculi as candidates for experimental investigations. Eighteen reindeer were inoculated in the right eye with CvHV2 (n = 5), M. bovoculi (n = 5), CvHV2 and M. bovoculi (n = 5) or sterile saline water (n = 3; controls).ResultsAll animals inoculated with CvHv2, alone or in combination with M. bovoculi, showed raised body temperature, increased lacrimation, conjunctivitis, excretion of pus and periorbital oedema; clinical signs that increased in severity from day 2 post inoculation (p.i.) and throughout the experiment, until euthanasia 5–7 days p.i. Examination after euthanasia revealed corneal oedema, and three animals displayed a corneal ulcer. CvHV2 could be identified in swab samples from both the inoculated eye and the control eye from most animals and time points, indicating a viral spread from the inoculation site.ConclusionsThis study showed that CvHV2 alone and in combination with M. bovoculi was able to cause the characteristic clinical signs of IKC in reindeer, whereas inoculation of M. bovoculi alone, originally isolated from a reindeer with IKC, did not produce clinical signs. Previous studies have suggested that herding procedures, animal stress and subsequent reactivation of latent CvHV2 infection in older animals is a plausible mechanism for IKC outbreaks among reindeer calves and young animals in reindeer herds. However, further studies are needed to fully understand the infection biology and epidemiology associated with IKC in reindeer.

Quantum dynamics of a four-well Bose-Hubbard model with two different tunneling rates

We consider a theoretical model of a four-mode Bose-Hubbard model consisting of two pairs of wells coupled via two processes with two different rates. The model is naturally divided into two subsystems with strong intra-system coupling and much weaker coupling between the two subsystems and has previously been introduced as a model for Josephson heat oscillations by Strzys and Anglin [\pra {\bf 81}, 043616 (2010) ]. We examine the quantum dynamics of this model for a range of different initial conditions, in terms of both the number distribution among the wells and the quantum statistics. We find that the time evolution is different to that predicted by a mean-field model and that this system exhibits a wide range of interesting behaviours. We find that the system equilibriates to a maximum entropy state and is thus a useful model for quantum thermalisation. As our model may be realised to a good approximation in the laboratory, it becomes a candidate for experimental investigation.

Structure Stability of Lytic Peptides During Their Interactions With Lipid Bilayers

In this work, molecular dynamics simulations were used to examine the consequences of a variety of analogs of cecropin A on lipid bilayers. Analog sequences were constructed by replacing either the N- or C-terminal helix with the other helix in native or reverse sequence order, by making palindromic peptides based on both the N- and C-terminal helices, and by deleting the hinge region. The structure of the peptides was monitored throughout the simulation. The hinge region appeared not to assist in maintaining helical structure but help in motion flexibility. In general, the N-terminal helix of peptides was less stable than the C- terminal one during the interaction with anionic lipid bilayers. Sequences with hydrophobic helices tended to regain helical structure after an initial loss while sequences with amphi- pathic helices were less able to do this. The results suggests that hydrophobic design pep- tides have a high structural stability in an anionic membrane and are the candidates for experimental investigation.

Besides N(2), What Is the Most Stable Molecule Composed Only of Nitrogen Atoms?

Polynitrogen molecules have been studied systematically at high levels of ab initio and density functional theory (DFT). Besides N(2), the thermodynamically most stable N(n)() molecules, located with the help of a newly developed energy increment system, are all based on pentazole units. The geometric, energetic, and magnetic criteria establish pentazole (2) and its anion (3) to be as aromatic as their isoelectronic analogues, e.g., furan, pyrrole, and the cyclopentadienyl anion. The bond lengths in 2 and 3 are equalized; both have large aromatic stabilization energies (ASE) and also substantial magnetic susceptibility exaltations (Lambda). The C(s)() symmetric azidopentazole (14), a candidate for experimental investigation, is the lowest energy N(8) isomer but is still 196.7 kcal/mol higher in energy than four N(2) molecules. Octaazapentalene (12) with 10 pi electrons also is aromatic. The D(2)(d)() symmetric bispentazole (21) is the lowest energy N(10) minimum but is 260 kcal/mol higher in energy than five N(2) molecules. For strain-free molecules, the average deviation is +/-2.6 kcal/mol between the DFT energies and those based on the increment scheme. The increment scheme also provides estimates of the strain energies of polynitrogen compounds, e.g., tetraazatetrahedrane (8, 48.2 kcal/mol), octaazacubane (11, 192.6 kcal/mol), and N(20) (27, 294.6 kcal/mol), and is useful in searching for new high-energy-high-density materials.