Nanodiamond powder was annealed at each of the following temperatures: 300, 600, 800, 1000, and 1150 °C, for an hour in flowing argon ambient. The variations of x-ray diffraction patterns and Raman spectra of the powder with different annealing temperatures were studied. While being annealed at temperatures higher than 800 °C, the powder can undergo a phase-transition process from cubic diamond to graphite. In addition, the size of nanodiamond crystallites decreased from ∼50 to ∼25 Å. The physical mechanism responsible for the variation in Raman spectra is discussed using a phonon-confinement model.

High-rate biological conversion of sulfide and nitrate in synthetic wastewater to, respectively, elemental sulfur (S(0)) and nitrogen-containing gas (such as N(2)) was achieved in an expanded granular sludge bed (EGSB) reactor. A novel strategy was adopted to first cultivate mature granules using anaerobic sludge as seed sludge in sulfate-laden medium. The cultivated granules were then incubated in sulfide-laden medium to acclimate autotrophic denitrifiers. The incubated granules converted sulfide, nitrate, and acetate simultaneously in the same EGSB reactor to S(0), N-containing gases and CO(2) at loading rates of 3.0 kg S m(-3) d(-1), 1.45 kg N m(-3) d(-1), and 2.77 kg Ac m(-1) d(-1), respectively, and was not inhibited by sulfide concentrations up to 800 mg l(-1). Effects of the C/N ratio on granule performance were identified. The granules cultivated in the sulfide-laden medium have Pseudomonas spp. and Azoarcus sp. presenting the heterotrophs and autotrophs that co-work in the high-rate EGSB-SDD (simultaneous desulfurization and denitrification) reactor.

This study studied the cultivation of granules from an expanded granular sludge bed reactor that simultaneously transforms sulfates, nitrates, and oxygen to elementary sulfur, nitrogen gas, and carbon dioxides, respectively. The living cells accumulate at the granule outer layers, as revealed by the multicolor staining and confocal laser scanning microscope technique. The microbial community comprises sulfate-reducing bacteria (SRB, Desulfomicrobium sp.), heterotrophic (Pseudomonas aeruginosa and Sulfurospirillum sp.), and autotrophic denitrifiers (Sulfurovum sp. and Paracoccus denitrificans) whose population dynamics at different sulfate and nitrate loading rates are monitored with the single-strand conformation polymorphism and denaturing gradient gel electrophoresis technique. The Desulfomicrobium sp. presents one of the dominating strains following reactor startup. At high sulfate and nitrate loading rates, the heterotrophic denitrifiers overcompete autotrophic denitrifiers to reduce SRB activities. Conversely, suddenly reducing nitrate loading rates completely removes the heterotrophic denitrifier Sulfurospirillum sp. from the granules and activates the autotrophic denitrifiers. The physical fixation of different groups of functional strains in granules fine-tunes the strains' activities, and hence the reactor performance.

pH-Triggered smart drug release for the treatment of bacterial infection.