We measured firstand second-order Raman scattering in cubic and hexagonal boron nitride using excitation energies in the visible and in the UV. The nonresonant first-order Raman susceptibilities for cubic and hexagonal BN are 1 and 10 Å2, respectively. Raman scattering is thus very powerful in detecting the hexagonal phase in mixed thin boron nitride films. In cubic BN the constant Raman sucsep...

2 • 2 hexagonal structure, two frequency bands can be now placed at the same sheet in contrast to the single hexagonal structure where it can appear only one frequency band. This double hexagonal structure can bring improvements for the operators and may allow them to enhance many new factors. In particular, it can be used to enhance security energy and spacial flexibility in cellular networks....

When the surface of a nominally flat binary material is bombarded with a broad, normally incident ion beam, disordered hexagonal arrays of nanodots can form. Shipman and Bradley have derived equations of motion that govern the coupled dynamics of the height and composition of such a surface [Shipman and Bradley, Phys. Rev. B 84, 085420 (2011)]. We investigate the influence of initial conditions...

Electrophilic ring opening of spiro-cyclopropanecarboxylated sugars followed by reaction with DBU revealed interesting ring-contraction and ring-expansion reactions depending on the substrate and the kind of hydroxyl protective group present adjacent to the spiro center. A stereoselective method for accessing a new class of carbon chain extended keto-furanoses and C-glycosylated bicyclic compou...

Liquid crystalline materials comprised of a cyclic ring core and pendant triphenyl groups have been prepared. Differential scanning calorimetry (DSC) and polarized optical microscopy (POM) were utilized to identify the presence of the mesophases. X-ray diffraction (XRD) techniques confirmed that these liquid crystalline materials were discotic. The hexagonal nature of these triphenyl-based disc...

Embedding non-hexagonal rings into sp2-hybridized carbon networks is considered a promising strategy to enrich the family of low-dimensional graphenic structures. However, non-hexagonal rings are energetically unstable compared to the hexagonal counterparts, making it challenging to embed non-hexagonal rings into carbon-based nanostructures in a controllable manner. Here, we report an on-surfac...

The synthesis and characterization of a fluorene–spirobifluorene alternating copolymer, P(OF-SBF), are described. In the case of the spiro-segment, the two fluorene rings are orthogonally arranged and connected through a tetrahedral bonding carbon atom (the spiro center). As a consequence, the polymer chain periodically zigzags, with an angle of 90u at each spiro center. This structural feature...

Salt-induced fluid lamellar (L alpha) to inverted hexagonal (HII) phase transitions have been studied in diphosphatidylglycerols (cardiolipins) with different acyl chain compositions, using 31P nuclear magnetic resonance (NMR) spectroscopy. Cardiolipins with four myristoyl chains, tetramyristoyl cardiolipin (TMCL), and with four oleoyl chains, tetraoleoyl cardiolipin (TOCL), were synthesized ch...

Hexagonal structure is different from the traditional square structure for image representation. The geometrical arrangement of pixels on hexagonal structure can be described in terms of a hexagonal grid. Uniformly separating image into seven similar copies with a smaller scale has commonly been used for parallel and accurate image processing including image compression on hexagonal structure. ...

We predict the number of hexagonal systems consisting of 24 and 25 hexagons to be H 24 = 122237774262384 and H 25 = 606259305418149, with 6 and 5 signiicant digits, respectively. Further estimates for H n up to n = 31 are also given. Informally speaking, a hexagonal system can be viewed as a connected arrangement of hexagonal cells packed in the same way as the typical honeycomb arrangement in ...