A mixture of bulk hexagonal boron nitride (h-BN) with hydrazine, 30% H(2)O(2), HNO(3)/H(2)SO(4), or oleum was heated in an autoclave at 100 °C to produce functionalized h-BN. The product formed stable colloid solutions in water (0.26-0.32 g L(-1)) and N,N-dimethylformamide (0.34-0.52 g L(-1)) upon mild ultrasonication. The yield of "soluble" h-BN reached about 70 wt%. The dispersions contained few-layered h-BN nanosheets with lateral dimensions in the order of several hundred nanometers. The functionalized dispersible h-BN was characterized by IR spectroscopy, X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, UV/Vis spectroscopy, X-ray diffraction (XRD), dynamic light scattering (DLS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and atomic force microscopy (AFM). It is shown that h-BN preserves its hexagonal structure throughout the functionalization procedure. Its exfoliation into thin platelets upon contact with solvents is probably owing to the attachment of hydrophilic functionalities.

Bacteriophage phiKZ was investigated by atomic force microscopy (AFM) and transmission electron microscopy (TEM). The well-known phage T4 was used as a reference sample. Reproducible contact mode AFM images of native and partially disintegrated particles of bacteriophage phiKZ in air were obtained. It was demonstrated that the heads of phiKZ and T4 phages were compressed differently and depended on adsorption onto highly ordered pyrolytic graphite and mica. We have established a procedure to partially disintegrate the viral particles after which the internal protein body, which is a helical structure with a cylinder-like form, was easily observable inside the bacteriophage phiKZ head.

No abstract

The chemical vapor deposition of pyrolytic boron nitride from borazine (the B3N3H6–N2 system) in the temperature range of 1300–1800 °C and chamber pressures of 1–10 Torr has been studied using a cold-wall reactor. The density, phase composition and B/N ratio of the samples (0.2–0.8 mm thick) have been measured. The deposition process from borazine is controlled by diffusion and produces stoichiometric boron nitride with a high fraction of the hexagonal phase of boron nitride in the samples. Employing borazine as a precursor reduces the temperature of formation of h-BN in comparison with the well-known BCl3–NH3–N2 system.

No abstract