Preparation and properties of chemically reduced graphene oxide/copolymer-polyamide nanocomposites

Liu, Xin; Shao, Xiao Yu; Fang, Guan; He, Hai Feng; Wan, Zhen

doi:10.1515/epoly-2016-0094

Cited by 24 publications

(9 citation statements)

References 26 publications

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“…Ultra-thin slices of B. subtilis bacteria cultured at different Mg/Ca ratios and in the liquid culture medium without any Mg 2+ and Ca 2+ ions were prepared according to the literature [40]. The ultra-thin slices of B. subtilis bacteria were analyzed by HRTEM (H-7650, Hitachi, Tokyo, Japan) [90], SAED, and STEM (Tecnai G 2 F20, FEI, Hillsboro, OR, USA).…”

Section: Analyses Of Intracellular Biomineralizationmentioning

confidence: 99%

Mechanism of Biomineralization Induced by Bacillus subtilis J2 and Characteristics of the Biominerals

et al. 2019

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Biomineralization induced by microorganisms has become a hot spot in the field of carbonate sedimentology; however, the mechanisms involved still need to be explored. In this study, the bacterium Bacillus subtilis J2 (GenBank MG575432) was used to induce the precipitation of calcium carbonate minerals at Mg/Ca molar ratios of 0, 3, 6, 9, and 12. Bacillus subtilis J2 bacteria released ammonia to increase pH, but the ammonia released only made the pH increase to 8.25. Carbonic anhydrase was also produced to catalyze the hydration of carbon dioxide, and this process released carbonate and bicarbonate ions that not only increased pH but also elevated carbonate supersaturation. The biominerals formed at a Mg/Ca molar ratio of 0 were spherulitic, elongated, dumbbell-shaped, and irregularly rhombohedral calcite; at a Mg/Ca molar ratio of 3, the biominerals were calcite and aragonite, the weight ratio of calcite decreased from 26.7% to 15.6%, and that of aragonite increased from 73.3% to 84.4% with increasing incubation time. At higher Mg/Ca molar ratios, the biominerals were aragonite, and the crystallinity and thermal stability of aragonite decreased with increasing Mg/Ca molar ratios. FTIR results showed that many organic functional groups were present on/within the biominerals, such as C–O–C, N–H, C=O, O–H, and C–H. HRTEM-SAED examination of the ultra-thin slices of B. subtilis J2 bacteria showed that nano-sized minerals with poor crystal structure had grown or been adsorbed on the EPS coating. The EPS of the B. subtilis J2 strain contained abundant glutamic acid and aspartic acid, which could be deprotonated in an alkaline condition to adsorb Ca2+ and Mg2+ ions; this made EPS act as the nucleation sites. This study may provide some references for further understanding of the mechanism of biomineralization induced by microorganisms.

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Section: Analyses Of Intracellular Biomineralizationmentioning

confidence: 99%

Mechanism of Biomineralization Induced by Bacillus subtilis J2 and Characteristics of the Biominerals

et al. 2019

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“…At last, 30% epoxy resin solution was added to embed the cells. The ultrathin slices were analyzed by high-resolution transmission electron microscopy (HRTEM, H-7650, Hitachi, Tokyo, Japan) [57,58,[62][63][64][65], scanning transmission microscopy (STEM, Tecnai G 2 F20, FEI, Hillsboro, OR, USA) and EDS. The parameters of these instruments are given in articles [66][67][68][69][70].…”

Section: Analysis Of the Ultrathin Slices Of B Licheniformismentioning

confidence: 99%

Extracellular and Intracellular Biomineralization Induced by Bacillus licheniformis DB1-9 at Different Mg/Ca Molar Ratios

et al. 2018

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Biomineralization has become a research hotspot and attracted widespread attention in the field of carbonate sedimentology. In this study, precipitation of carbonate minerals was induced by Bacillus licheniformis DB1-9 bacteria, (identity confirmed with its phylogenetic tree), to further explore the biomineralization mechanisms. During experiments, lasting up to 24 days with varying Mg/Ca molar ratios and regular monitoring of conditions, ammonia and carbonic anhydrase are released by the bacteria, resulting in a pH increase. Carbonic anhydrase could have promoted carbon dioxide hydration to produce bicarbonate and carbonate ions, and so promoted supersaturation to facilitate the precipitation of carbonate minerals. These include rhombohedral, dumbbell-shaped, and elongated calcite crystals; aragonite appears in the form of mineral aggregates. In addition, spheroidal and fusiform minerals are precipitated. FTIR results show there are organic functional groups, such as C–O–C and C=O, as well as the characteristic peaks of calcite and aragonite; these indicate that there is a close relationship between the bacteria and the minerals. Ultrathin slices of the bacteria analyzed by HRTEM, SAED, EDS, and STEM show that precipitate within the extracellular polymeric substances (EPS) has a poor crystal structure, and intracellular granular areas have no crystal structure. Fluorescence intensity and STEM results show that calcium ions can be transported from the outside to the inside of the cells. This study provides further insights to our understanding of biomineralization mechanisms induced by microorganisms.

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“…100%(15 min), at last 30% epoxy resin solution was added to embed the cells. The completed ultra-thin slices were analyzed with TEM (JEM-2100, Japan)[81,[88][89][90][91], HRTEM (H-7650, Hitachi, Japan)…”

mentioning

confidence: 99%

The Significant Role of Different Magnesium: Carbonate Minerals Induced by Moderate Halophile <em>Staphylococcus epidermis</em> Y2

Han¹,

Yu²,

Zhao³

et al. 2018

Preprint

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Carbonate precipitation induced by microorganism has become a hot spot in the field of carbonate sedimentology, while the effect of different magnesium on biominerals has rarely been studied. Therefore, magnesium sulfate and magnesium chloride were used to investigate the significant role played on carbonate minerals. In this study, Staphylococcus epidermidis Y2 was isolated and identified by 16S rDNA homology comparison. The ammonia, pH, carbonic anhydrase, carbonate and bicarbonate ions were investigated. The mineral phase, morphology and elemental composition were analyzed by XRD and SEM-EDS. The ultrathin slices of bacteria were analyzed by HRTEM-SAED and STEM. The result showed that this bacterium could release ammonia and carbonic anhydrase to increase pH, and elevate the supersaturation via a large number of carbonate and bicarbonate ions released through carbon dioxide hydration catalyzed by carbonic anhydrase. The crystal cell density of monohydrocalcite was lower in magnesium chloride medium than that in magnesium sulfate medium. The crystal grew in a mode of spiral staircas in magnesium sulfate medium, while in a concentric circular pattern in magnesium chloride medium. There was no obvious intracellular biomineralization. This study may be helpful to further understand the biomineralization mechanism, may also provide some references for the reconstruction of paleogeological environment.

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Preparation and properties of chemically reduced graphene oxide/copolymer-polyamide nanocomposites

Cited by 24 publications

References 26 publications

Mechanism of Biomineralization Induced by Bacillus subtilis J2 and Characteristics of the Biominerals

Mechanism of Biomineralization Induced by Bacillus subtilis J2 and Characteristics of the Biominerals

Extracellular and Intracellular Biomineralization Induced by Bacillus licheniformis DB1-9 at Different Mg/Ca Molar Ratios

The Significant Role of Different Magnesium: Carbonate Minerals Induced by Moderate Halophile <em>Staphylococcus epidermis</em> Y2

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