Community analysis of biofilms on flame-oxidized stainless steel anodes in microbial fuel cells fed with different substrates

BackgroundThe flame-oxidized stainless steel anode (FO-SSA) is a newly developed electrode that enhances microbial fuel cell (MFC) power generation; however, substrate preference and community structure of the biofilm developed on FO-SSA have not been well characterized. Herein, we investigated the community on FO-SSA using high-throughput sequencing of the 16S rRNA gene fragment in acetate-, starch-, glucose-, and livestock wastewater-fed MFCs. Furthermore, to analyze the effect of the anode material, the acetate-fed community formed on a common carbon-based electrode—carbon-cloth anode (CCA)—was examined for comparison.ResultsSubstrate type influenced the power output of MFCs using FO-SSA; the highest electricity was generated using acetate as a substrate, followed by peptone, starch and glucose, and wastewater. Intensity of power generation using FO-SSA was related to the abundance of exoelectrogenic genera, namely Geobacter and Desulfuromonas, of the phylum Proteobacteria, which were detected at a higher frequency in acetate-fed communities than in communities fed with other substrates. Lactic acid bacteria (LAB)—Enterococcus and Carnobacterium—were predominant in starch- and glucose-fed communities, respectively. In the wastewater-fed community, members of phylum Planctomycetes were frequently detected (36.2%). Exoelectrogenic genera Geobacter and Desulfuromonas were also detected in glucose-, starch-, and wastewater-fed communities on FO-SSA, but with low frequency (0–3.2%); the lactate produced by Carnobacterium and Enterococcus in glucose- and starch-fed communities might affect exoelectrogenic bacterial growth, resulting in low power output by MFCs fed with these substrates. Furthermore, in the acetate-fed community on FO-SSA, Desulfuromonas was abundant (15.4%) and Geobacter had a minor proportion (0.7%), while in that on CCA, both Geobacter and Desulfuromonas were observed at similar frequencies (6.0–9.8%), indicating that anode material affects exoelectrogenic genus enrichment in anodic biofilm.ConclusionsAnodic community structure was dependent on both substrate and anode material. Although Desulfuromonas spp. are marine microorganisms, they were abundant in the acetate-fed community on FO-SSA, implying the presence of novel non-halophilic and exoelectrogenic species in this genus. Power generation using FO-SSA was positively related to the frequency of exoelectrogenic genera in the anodic community. Predominant LAB in saccharide-fed anodic biofilm caused low abundance of exoelectrogenic genera and consequent low power generation

Effect of Gold Nanoparticle Distribution in TiO2 on the Optical and Electrical Characteristics of Dye-Sensitized Solar Cells

Abstract Photoanodes comprising Au nanoparticles (GNPs) and thin TiO2 layers with a stacked structure were fabricated by repeating the application of TiO2 paste and GNP solutions on conductive glass to vary the distribution of GNPs in the TiO2 layer. The plasmon-enhanced characteristics of dye-sensitized solar cells (DSSCs) with such photoanodes were investigated. Both the absorption of the TiO2 layer and the performance of the DSSC are found to be most increased by plasmonic enhancement when GNPs are concentrated near the position in the TiO2 layer, which is the penetration depth of the incident light of wavelength corresponding to the maximum absorption of the N719 dye (~ 520 nm). When a GNP layer with a relatively high density of 1.3 μg/cm2 density was formed at its position, and two GNP layers with a relatively low density of 0.65 μg/cm2 were formed near the front side of the incident light, the short-circuit current density (Jsc) and energy conversion efficiency (η) of the DSSC were found to be 10.8 mA/cm2 and 5.0%, increases of 15 and 11%, respectively, compared with those of the DSSC without GNPs. Our work suggests that optimization of the distribution of GNPs in the TiO2 layer is very important for improving the performance of DSSCs fabricated by utilizing GNPs

Formation mechanisms of local structures in language networks

The small-world property has recently been observed in several language networks generated in terms of word co-occurrence. However, a syntactic interpretation of this universal property has not yet been clarified. This study aims to reveal the formation mechanism of local structures involving small-world properties of co-occurrence language networks. We analyse local structures of language networks with directed edges generated from five different languages, where the directed edges provide word-order information. The results show that the following three syntactic properties play a leading role in the formation of the local structure of a language network: i) agglutination of words, ii) changes in the positions of words, and iii) basic word orders of languages. We further show that a common formation mechanism exists in local structures, even though the syntactic rules vary between the considered languages. These syntactic properties potentially drive the small-world property of language networks

Additional file 2: Figure S2. of Effect of Gold Nanoparticle Distribution in TiO2 on the Optical and Electrical Characteristics of Dye-Sensitized Solar Cells

(a) Jsc and (b) η of the DSSCs with varying the density of GNPs. GNP layers were formed at the interface between the conductive glass and TiO2 layers of 1.4 μm (3rd and 4th lots) and 1.8 μm (5th lot) thicknesses, respectively. (PDF 278 kb

Community analysis of biofilms on flame-oxidized stainless steel anodes in microbial fuel cells fed with different substrates

Abstract Background The flame-oxidized stainless steel anode (FO-SSA) is a newly developed electrode that enhances microbial fuel cell (MFC) power generation; however, substrate preference and community structure of the biofilm developed on FO-SSA have not been well characterized. Herein, we investigated the community on FO-SSA using high-throughput sequencing of the 16S rRNA gene fragment in acetate-, starch-, glucose-, and livestock wastewater-fed MFCs. Furthermore, to analyze the effect of the anode material, the acetate-fed community formed on a common carbon-based electrode—carbon-cloth anode (CCA)—was examined for comparison. Results Substrate type influenced the power output of MFCs using FO-SSA; the highest electricity was generated using acetate as a substrate, followed by peptone, starch and glucose, and wastewater. Intensity of power generation using FO-SSA was related to the abundance of exoelectrogenic genera, namely Geobacter and Desulfuromonas, of the phylum Proteobacteria, which were detected at a higher frequency in acetate-fed communities than in communities fed with other substrates. Lactic acid bacteria (LAB)—Enterococcus and Carnobacterium—were predominant in starch- and glucose-fed communities, respectively. In the wastewater-fed community, members of phylum Planctomycetes were frequently detected (36.2%). Exoelectrogenic genera Geobacter and Desulfuromonas were also detected in glucose-, starch-, and wastewater-fed communities on FO-SSA, but with low frequency (0–3.2%); the lactate produced by Carnobacterium and Enterococcus in glucose- and starch-fed communities might affect exoelectrogenic bacterial growth, resulting in low power output by MFCs fed with these substrates. Furthermore, in the acetate-fed community on FO-SSA, Desulfuromonas was abundant (15.4%) and Geobacter had a minor proportion (0.7%), while in that on CCA, both Geobacter and Desulfuromonas were observed at similar frequencies (6.0–9.8%), indicating that anode material affects exoelectrogenic genus enrichment in anodic biofilm. Conclusions Anodic community structure was dependent on both substrate and anode material. Although Desulfuromonas spp. are marine microorganisms, they were abundant in the acetate-fed community on FO-SSA, implying the presence of novel non-halophilic and exoelectrogenic species in this genus. Power generation using FO-SSA was positively related to the frequency of exoelectrogenic genera in the anodic community. Predominant LAB in saccharide-fed anodic biofilm caused low abundance of exoelectrogenic genera and consequent low power generation

Multicenter Analysis of mFOLFOX6 with Oxaliplatin Stop-and-Go Strategy Using Oral Uracil-Tegafur with Leucovorin for Unresectable Colorectal Cancer in Elderly Patients

International audience(Civ. 3e, 12 juin 1991, Bull. civ. III, n° 173, p. 102 ; Defrénois 1991, p. 1014, obs. H. Souleau.