Enhancement of nitrate reduction in microbial fuel cells by acclimating biocathode potential: Performance, microbial community, and mechanism.

The enhancement of nitrate reduction in microbial fuel cells (MFCs) by acclimating biocathode potential was studied. An MFC system was started up, and measured by cyclic voltammetry to determine a suitable potential region for acclimating biocathode. The experimental results revealed that potential acclimation could efficiently improve denitrification performance by relieving the phenomenon of nitrite accumulation, and optimum performance was obtained at -0.4 V with a total nitrogen removal efficiency of 87.4 %. Subsequently, the characteristics of electron transfer behaviors were measured, suggesting that a positive correlation between nitrate reduction and the contribution of direct electron transfer emerged. Furthermore, a denitrification mechanism was proposed. The results indicated that potential acclimation was conducive to enhancing denitrifying enzyme activity and that the electron transport system activity could be increased by 5.8 times. This study provides insight into the electron transfer characteristics and denitrification mechanisms in MFCs for nitrate reduction at specific acclimatization potentials.

Theoretical calculations and experimental investigation toward the π-conjugated modulation in arylamine derivative-based hole transporting materials for perovskite solar cells.

Excellent hole transporting materials (HTMs) are beneficial to promote the performance of perovskite solar cells (PSCs). Herein, starting from the modulation of the π-conjugated groups of carbazole-diphenylamine derivatives, HTMs CY1 and CY2 were designed and investigated using density functional theory and Marcus theory. Theoretical simulations show that CY1 and CY2 exhibit appropriate HOMO/LUMO energy levels, small recombination energy, good optical properties and molecular stability. Compared with CY1, CY2 with a larger π-conjugated group on its side chain can yield a higher hole mobility and better charge separation. The experimental results confirm that CY2 in PSCs exhibits superior properties such as good hole transporting ability, good film morphology, and efficient charge extraction and dissociation at perovskite/HTM inerfaces. Therefore, a PSC device with CY2 yields a higher efficiency than those of CY1- and Spiro-OMeTAD-based devices. Hence, the results demonstrate that the strategy of the extended π-π conjugation on a side chain is a practicable approach to design potential HTMs for application in PSCs.

Immunoregulatory activity of a low-molecular-weight heteropolysaccharide from Ganoderma leucocontextum fruiting bodies in vitro and in vivo.

The chemical structure of GLP-1, a novel water-soluble heteropolysaccharide purified Ganoderma leucocontextum fruiting bodies, has been characterized in our previous study. This study aimed to investigate the immunostimulatory activity of GLP-1 in vitro and in vivo by using RAW264.7 macrophages and cyclophosphamide-induced immunosuppressed mice model. Results showed that GLP-1 was able to enhance phagocytic activity and promote the production of reactive oxygen species, nitric oxide, tumor necrosis factor-α, interleukin-6, and monocyte chemoattractant protein-1 in RAW264.7 macrophages. Moreover, GLP-1 could activate mitogen-activated protein kinase, phosphatidylinositol-3-kinase/protein kinase B, and nuclear factor-kappa B signaling pathways through toll-like receptor 2 and dectin-1 receptors. Furthermore, GLP-1 increased the thymus index, serum immunoglobulin levels, and percentage of CD3+ T lymphocytes in cyclophosphamide-induced immunosuppressed mice. These results demonstrated that GLP-1 possessed significant immunostimulatory effects in vivo and in vitro and could be developed as an effective immunomodulator for application in functional foods.

Strong Structural Modification of Gd to Co3O4 for Catalyzing N2O Decomposition under Simulated Real Tail Gases.

In this paper, Gd-promoted Co3O4 catalysts were prepared via a facile coprecipitation method for low-temperature catalytic N2O decomposition. Due to the addition of Gd, the crystallite size of Co3O4 in the Gd0.06Co catalyst surprisingly decreased to 4.9 nm, which is much smaller than most additive-modified Co3O4 catalysts. This huge change in the catalyst's textural structure endows the Gd0.06Co catalyst with a large specific surface area, plentiful active sites, and a weak Co-O bond. Hence, Gd0.06Co exhibited superior activity for catalyzing 2000 ppmv N2O decomposition, and the temperature for the complete catalytic elimination of N2O was as low as 350 °C. Meanwhile, compared with pure Co3O4, Ea decreased from 77.4 to 46.8 kJ·mol-1 and TOF of the reaction increased from 1.16 × 10-3 s-1 to 5.13 × 10-3 s-1 at 300 °C. Moreover, Gd0.06Co displayed a quite stable catalytic performance in the presence of 100 ppmv NO, 5 vol % O2, and 2 vol % H2O.

Purification, Physicochemical Properties, and Antioxidant Activities of Two Low-Molecular-Weight Polysaccharides from Ganoderma leucocontextum Fruiting Bodies.

Two low-molecular-weight polysaccharides (GLP-1 and GLP-2) were purified from Ganoderma leucocontextum fruiting bodies, and their physicochemical properties and antioxidant activities were investigated and compared in this study. The results showed that GLP-1 and GLP-2 were mainly composed of mannose, glucose, galactose, xylose, and arabinose, with weight-average molecular weights of 6.31 and 14.07 kDa, respectively. Additionally, GLP-1 and GLP-2 had a similar chain conformation, crystal structure, and molecular surface morphology. Moreover, GLP-1 exhibited stronger antioxidant activities than GLP-2 in five different assays: 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS), hydroxyl radical, superoxide anion radical, ferric reducing antioxidant power (FRAP), and oxygen radical antioxidant capacity (ORAC). The main linkage types of GLP-1 were found to be →4)-α-D-Glcp-(1→, →4)-ß-D-Glcp-(1→, →3)-ß-D-Glcp-(1→, →6)-ß-D-Galp-(1→, →6)-α-D-Glcp-(1→, →4,6)-α-D-Glcp-(1→, and Glcp-(1→ by methylation analysis and nuclear magnetic resonance (NMR) spectroscopy. In addition, GLP-1 could protect NIH3T3 cells against tert-butyl hydroperoxide (tBHP)-induced oxidative damage by increasing catalase (CAT) and glutathione peroxidase (GSH-Px) activities, elevating the glutathione/oxidized glutathione (GSH/GSSG) ratio, and decreasing the malondialdehyde (MDA) level. These findings indicated that GLP-1 could be explored as a potential antioxidant agent for application in functional foods.

Structural characterization and immunomodulatory activity of a water-soluble polysaccharide from Ganoderma leucocontextum fruiting bodies.

Ganoderma leucocontextum is a new species of Ganoderma discovered in 2014. Up to now, the structural characteristics and immunoregulatory activity of its polysaccharides remain virtually unknown. In this study, a water-soluble polysaccharide termed, GLP-3, was purified from G. leucocontextum by ultrafiltration and column chromatography. The results revealed that GLP-3 mainly consisted of glucose (92.7 %) and its weight average molecular weight was 159.7 kDa. The structural analysis indicated that the backbone of GLP-3 was →4)-α-D-Glcp-(1→4,6)-ß-D-Glcp-(1→ with a ß-Glcp-(1→ branch. Atomic force microscopy and Congo red experiments revealed that GLP-3 might possess a globular structure with triple-helix conformation in water. Moreover, GLP-3 was recognized by toll-like receptor 2 (TLR2) and exerted immunomodulatory effects via activating mitogen-activated protein kinases (MAPKs), phosphatidylinositol-3-kinase (PI3K)/Akt and nuclear factor-κB (NF-κB) signaling pathways in RAW 264.7 macrophages. Collectively, these results suggested that GLP-3 could be developed as a potential functional food ingredient for immunomodulation.