Complete Genome Sequence of Strain SS-5, a Magnetotactic Gammaproteobacterium Isolated from the Salton Sea, a Shallow, Saline, Endorheic Rift Lake Located on the San Andreas Fault in California

ABSTRACT We report the 3.7-Mb genome sequence of strain SS-5, a magnetotactic, sulfur-oxidizing rod and member of the family Chromatiaceae of the class Gammaproteobacteria, which biomineralizes membrane-bound, elongated, prismatic octahedral, magnetite nanocrystals. This genome sequence brings further diversity for understanding the origin and evolution of magnetotaxis and magnetosome biomineralization.

Magnetic-field-assisted synthesis of anisotropic iron oxide particles: Effect of pH

The synthesis of magnetite (Fe3O4) nanorods using reverse co-precipitation of Fe3+ and Fe2+ ions in the presence of a static magnetic field is reported in this work. The phase composition and crystal structure of the synthesized material were investigated using electron diffraction, Raman spectroscopy, and transmission electron microscopy. It was shown that the morphology of the reaction product strongly depends on the amount of OH− ions in the reaction mixture, varying from Fe3O4 nanorods to spherical Fe3O4 nanoparticles. Fe3O4 nanorods were examined using high-resolution transmission electron microscopy proving that they are single-crystalline and do not have any preferred crystallographic orientation along the axis of the rods. According to the data obtained a growth mechanism was proposed for the rods that consists of the dipole–dipole interaction between their building blocks (small hexagonal faceted magnetite nanocrystals), which are formed during the first step of the reaction. The study suggests a facile, green and controllable method for synthesizing anisotropic magnetic nanoparticles in the absence of stabilizers, which is important for further modification of their surfaces and/or incorporation of the nanoparticles into different media.

Complete Genome Sequence of Strain BW-2, a Magnetotactic Gammaproteobacterium in the Family Ectothiorhodospiraceae, Isolated from a Brackish Spring in Death Valley, California

We report the complete 4.1-Mb genome sequence of strain BW-2, a magnetotactic, sulfur-oxidizing rod, belonging to the family Ectothiorhodospiraceae of the class Gammaproteobacteria, that biomineralizes membrane-bounded magnetite nanocrystals in its magnetosomes. This genome sequence, in comparison with those of other magnetotactic bacteria, is essential for understanding the origin and evolution of magnetotaxis and magnetosome biomineralization.

Microwave-Assisted Synthesis of Graphene Supported Hexagonal Magnetite for Applications in Catalysis

Herein, we report a rapid one-step synthetic method using microwave irradiation for growing magnetite nanocrystals on reduced graphene oxide sheets. This developed strategy allows decorating graphene sheets with magnetite nanocrystals of welldefined morphology as cubes using microwave-driven reduction of iron chloride using hydrazine hydrate as a reducing agent. The size and shape control was achieved via fine-tuning of the reaction conditions. The obtained results demonstrate the applicability of this microwave synthetic approach to control the morphology of the magnetite nanocrystals anchored on graphene sheets. Moreover, graphene sheets will enhance the nucleation and growth of magnetite nanoplates anchored on graphene. This approach can be used as a synthetic tool to synthesize a wide variety of metal and metal oxide architectures on graphene. This approach also provides plenty of advantages like catalyst recyclability, mild reaction conditions, easy separation, reproducibility, and minimization of agglomeration effect that cause the decrease in the catalyst catalytic activity

Нанокристаллы магнетита с повышенной константой магнитной анизотропии, наведенной формой частицы

Square-plated magnetite nanocrystals with a high aspect ratio (~ 1/9) are prepared by the co-precipitation from a solution in the presence of arabinogalactan. The magnetic anisotropy constant of particles is several times higher than the constant of spherical magnetite particles, which leads to increased hysteresis properties for specific volume of the particle.