We propose, on the basis of our first principles density functional based calculations, a new isomer of graphane, in which the C-H bonds of a hexagon alternate in 3-up, 3-down fashion on either side of the sheet. This 2D puckered structure called 'stirrup' has got a comparable stability with the previously discovered chair and boat conformers of graphane. The physico-chemical properties of this third conformer are found to be similar to the other two conformers of graphane with an insulating direct band gap of 3.1 eV at the Γ point. Any other alternative hydrogenation of the graphene

We report the results of thermoelectric power ͑TEP͒ of a Cr doped La 0.5 Pb 0.5 Mn 1Ϫx Cr x O 3 (xϭ0 -0.45) system measured both in the presence and the absence of magnetic field (Bϭ1.5 T). The small field dependence of the Seebeck coefficient is observed around the metal-semiconductor transition ͑MST͒ temperature (T p ) of the samples. The field dependence of TEP is stronger in the undoped sample. It is noticed from the TEP data that the small polaron hopping conduction mechanism is valid for all these samples ͑for TϾT p ). The polaron radius r p is found to decrease with increase of magnetic field. Low-temperature ͑below T p ) fielddependent and field-independent TEP data can be fitted with SϭS 0 ϩS 3/2 T 3/2 ϩS 4 T 4 suggesting that the electron-magnon scattering strongly affects the low-temperature ͑ferromagnetic phase͒ TEP data of the manganites. Activation energy gradually increases with increasing Cr concentration both in the presence and the absence of magnetic field. Field-dependent thermopower also indicates the importance of spin fluctuations affecting the phonon scattering. Power factor (S 2 /) estimated from the Seebeck coefficient ͑S͒ and resistivity () ͑at zero and 1.5 T field͒ showed a minimum around the MST temperature similar to the field-dependent thermal conductivity data.

Hydrogenation of graphene [1] called "graphane" [2, 3] is a hot pursuit today because of its various interesting properties [3 -5]. The impressive progress in graphene research has motivated scientists to explore various other 2D planar materials [6]. h-BN sheet has been cited as the possible analogue of graphene in various ways because of its similar lattice parameters [7]. BN sheet has been experimentally synthesized in single and multiple layers [7 -10]. It is worth looking into the possibility of hydrogenation of BN sheet, in the same spirit as graphane and study their structural and electronic properties. In recent past, there have been various reports on semi or fully hydrogenated BN sheet [11 -15]. In fully hydrogenated BN sheet (BHNH), each of the B and N atoms are bonded to one H atom and in some specific manners that give rise to various conformations of the sheet. These conformers show reasonably high stability and can also exist in single layer (with negligible or low interlayer binding). As in the case of graphane [2], here also we have the possibility of having 'chair ' and 'boat' conformers [15]. The objective of this letter is to propose a new conformer called "stirrup" [16] and compare its electronic structure and ground state properties with the existing BHNH conformers. The "stirrup" conformer resembles the structure of cubic BN (100) surface and is found to have higher stability than the previously reported conformers [11][12][13][14][15].We have carried out density functional theory (DFT) [17,18] based calculations using VASP [19] code with projected augmented wave (PAW) potential [20]. The GGA calculations have been performed using exchangecorrelation functional of Perdew et al. [21,22]. An energy cut-off of 600 eV was used. The k-mesh was generated by Monkhorst-Pack [23] method and all results were tested for convergence with respect to mesh size. In all our calculations, self-consistency has been achieved with 0.0001 eV convergences in total energy. For optimizing the ground state geometry [24,25] atomic forces were converged to less than 0.001 eV/Å via conjugate gradient minimization. In view of the fact that GGA does not satisfactorily describe the inter-layer interactions, we have used LDA calculations with Ceperley-Alder exchange -correlation [26] to estimate the inter-layer binding between various BHNH conformers.BN sheet can be looked upon as a 2D array of repetitive hexagonal BN units where each B (N) atom is bonded to three N (B) atoms [27]. The hydrogenation of BN sheet gives rise to various conformers (with formula unit BHNH) in which each of the B and N atoms of the sheet is bonded to one H atom in different orientations. All three BHNH conformers have stable symmetrically puckered zigzag 2D structure. The chair and boat BHNH conformers resemble in structure to those of graphane [2] (Fig. 1a -d).We report, using first principles density functional calculations, the relative stabilities, structural and electronic properties of various conformers of hydrogenated BN sheet (BHNH). T...

An unprecedented single crystal-to-single crystal transformation occurs when a binuclear oxovanadium(V) compound [V(V)(2)O(2)(L)(2)] 1 involving 2,6-bis(hydroxymethyl)-p-cresol (H(3)L) as a bridging ligand is exposed simultaneously to white light and aerial oxygen to generate an oligomeric compound [V(IV)(2)O(2)(L*)(2)] 2 (H(2)L* is 3-hydroxymethyl-5-methylsalicylaldehyde). Each vanadium(V) center in 1 is reduced to vanadium(IV) in 2 at the expense of a two-electron alcohol-to-aldehyde oxidation in the coordinated ligand. The additional electron being released is possibly consumed by molecular oxygen to generate hydrogen peroxide.

Species-specific identification of Vibrio fluvialis by PCR targeted to the conserved transcriptional activation and variable membrane tether regions of the toxR gene Vibrio fluvialis has been reported to cause sporadic infections and outbreaks of diarrhoea in humans (