Flame retardance-donated lignocellulose nanofibers (LCNFs) by the Mannich reaction with (amino-1,3,5-triazinyl)phosphoramidates and their properties.

Nitrogen/phosphorus-containing melamines (NPCM), a durable flame-retardant, were prepared by the successive treatment of ArOH (Ar = Br n C6H5-n , n = 0, 1, 2, and 3) with POCl3 and melamine monomer. The prepared flame-retardants were grafted through the CH2 unit to lignocellulose nanofibers (LCNFs) by the Mannich reaction. The resulting three-component products were characterized using FT-IR (ATR) and EA. The thermal behavior of the NPCM-treated LCNF fabric samples was determined using TGA and DSC analyses, and their flammability resistances were evaluated by measuring their Limited Oxygen Index (LOI) and the UL-94V test. A multitude of flame retardant elements in the fabric samples increased the LOI values as much as 45 from 20 of the untreated LCNFs. Moreover, the morphology of both the NPCM-treated LCNFs and their burnt fabrics was studied with a scanning electron microscope (SEM). The heat release lowering effect of the LCNF fabric against the water-based paint was observed with a cone calorimeter. Furthermore, the mechanical properties represented as the tensile strength of the NPCM-treated LCNF fabrics revealed that the increase of the NPCM content in the PP-composites led to an increased bending strength with enhancing the flame-retardance.

Isolation of a Leptothrix strain, OUMS1, from ocherous deposits in groundwater.

Leptothrix species in aquatic environments produce uniquely shaped hollow microtubules composed of aquatic inorganic and bacterium-derived organic hybrids. Our group termed this biologically derived iron oxide as "biogenous iron oxide (BIOX)". The artificial synthesis of most industrial iron oxides requires massive energy and is costly while BIOX from natural environments is energy and cost effective. The BIOX microtubules could potentially be used as novel industrial functional resources for catalysts, adsorbents and pigments, among others if effective and efficient applications are developed. For these purposes, a reproducible system to regulate bacteria and their BIOX productivity must be established to supply a sufficient amount of BIOX upon industrial demand. However, the bacterial species and the mechanism of BIOX microtubule formation are currently poorly understood. In this study, a novel Leptothrix sp. strain designated OUMS1 was successfully isolated from ocherous deposits in groundwater by testing various culture media and conditions. Morphological and physiological characters and elemental composition were compared with those of the known strain L. cholodnii SP-6 and the differences between these two strains were shown. The successful isolation of OUMS1 led us to establish a basic system to accumulate biological knowledge of Leptothrix and to promote the understanding of the mechanism of microtubule formation. Additional geochemical studies of the OUMS1-related microstructures are expected provide an attractive approach to study the broad industrial application of bacteria-derived iron oxides.

Nanometer-scale visualization and structural analysis of the inorganic/organic hybrid structure of Gallionella ferruginea twisted stalks.

The so-called Fe/Mn-oxidizing bacteria have long been recognized for their potential to form extracellular iron hydroxide or manganese oxide structures in aquatic environments. Bacterial species belonging to the genus Gallionella, one type of such bacteria, oxidize iron and produce uniquely twisted extracellular stalks consisting of iron oxide-encrusted inorganic/organic fibers. This paper describes the ultrastructure of Gallionella cells and stalks and the visualized structural and spatial localization of constitutive elements within the stalks. Electron microscopy with energy-dispersive X-ray microanalysis showed the export site of the stalk fibers from the cell and the uniform distribution of iron, silicon, and phosphorous in the stalks. Electron energy-loss spectroscopy revealed that the stalk fibers had a central carbon core of bacterial exopolymers and that aquatic iron interacted with oxygen at the surface of the carbon core, resulting in deposition of iron oxides at the surface. This new knowledge of the structural and spatial associations of iron with oxygen and carbon provides deeper insights into the unique inorganic/organic hybrid structure of the stalks.

Chemical modification of biogenous iron oxide to create an excellent enzyme scaffold.

The biogenous iron oxide (BIO) from Leptothrix ochracea was transformed to an organic-inorganic hybrid support to prepare an excellent immobilized enzyme showing high catalytic performance.