The metabolic profiling of Chinese yam fermented by Saccharomyces boulardii and the biological activities of its ethanol extract in vitro

Chinese yam(Dioscorea opposita Thunb.),as one of the medicinal and edible homologous plants,is rich in various nutrients and functional factors.In this study,Chinese yam fermented by Saccharomyces boulardii was performed to investigate its bioactive components and metabolic profile.And then,the main bioactive components and biological activities of fermented Chinese yam ethanol extract(FCYE)were evaluated.Results showed that there were 49 up-regulated metabolites and 52 down-regulated metabolites in fermented Chinese yam compared to unfermented Chinese yam.Besides,corresponding metabolic pathways analysis initially revealed that the distribution of bioactive substances was concentrated on alcoholsoluble small molecular substances.Ulteriorly,the total polyphenol content and the total flavonoid content in FCYE were significantly increased,and the corresponding antioxidant and immunomodulatory activities in vitro were also significantly enhanced.Our study provided a new reference for the comprehensive utilization of Chinese yam and laid a theoretical foundation for the development and application of natural probiotic-fermented products.

Protective eff ect and mechanism of nanoantimicrobial peptide ND-C14 against Streptococcus pneumoniae infection

BACKGROUND:Streptococcus pneumoniae(S.pneumoniae)is a common pathogen that causes bacterial pneumonia.However,with increasing bacterial resistance,there is an urgent need to develop new drugs to treat S.pneumoniae infections.Nanodefensin with a 14-carbon saturated fatty acid(ND-C14)is a novel nanoantimicrobial peptide designed by modifying myristic acid at the C-terminus of humanα-defensin 5(HD5)via an amide bond.However,it is unclear whether ND-C14 is effective against lung infections caused by S.pneumoniae.METHODS:In vitro,three groups were established,including the control group,and the HD5 and ND-C14 treatment groups.A virtual colony-count assay was used to evaluate the antibacterial activity of HD5 and ND-C14 against S.pneumoniae.The morphological changes of S.pneumoniae treated with HD5 or ND-C14 were observed by scanning electron microscopy.In vivo,mice were divided into sham,vehicle,and ND-C14 treatment groups.Mice in the sham group were treated with 25μL of phosphate-buffered saline(PBS).Mice in the vehicle and ND-C14 treatment groups were treated with intratracheal instillation of 25μL of bacterial suspension with 2×108 CFU/mL(total bacterial count:5×10^(6) CFU),and then the mice were given 25μL PBS or intratracheally injected with 25μL of ND-C14(including 20μg or 50μg),respectively.Survival rates were evaluated in the vehicle and ND-C14 treatment groups.Bacterial burden in the blood and bronchoalveolar lavage fluid were counted.The lung histology of the mice was assessed.A propidium iodide uptake assay was used to clarify the destructive eff ect of ND-C14 against S.pneumoniae.RESULTS:Compared with HD5,ND-C14 had a better bactericidal eff ect against S.pneumoniae because of its stronger ability to destroy the membrane structure of S.pneumoniae in vitro.In vivo,ND-C14 significantly delayed the death time and improved the survival rate of mice infected with S.pneumoniae.ND-C14 reduced bacterial burden and lung tissue injury.Moreover,ND-C14 had a membrane permeation eff ect on S.pneumoniae,and its destructive ability increased with increasing ND-C14 concentration.CONCLUSION:The ND-C14 may improve bactericidal eff ects on S.pneumoniae both in vitro and in vivo.

Modifi cation of wheat bran insoluble and soluble dietary fibers with snail enzyme

Insoluble dietary fiber(IDF)and soluble dietary fiber(SDF)extracted from wheat bran were modifi ed by snail enzyme and their physicochemical properties(water retention capacity and oil retention capacity),functional properties(cholesterol adsorption capacity,glucose adsorption capacity and antioxidant activity)and structural characterizations were evaluated.The results showed that snail enzyme modification led to the significant increase in oil retention capacity of IDF,glucose adsorption capacity and cholesterol adsorption capacity of IDF and SDF.Enzymatic modification also markedly improved the DPPH radical scavenging capacity and reducing power of IDF and SDF.Meanwhile,scanning electron microscopy(SEM)analysis indicated the microstructures of IDF and SDF powders were signifi cantly changed.Fourier transfer-infrared spectrometry(FT-IR)showed that snail enzyme modifi cation could degrade the part of cellulose and hemicellulose of IDF and SDF.All these improved physicochemical and functional properties of IDF and SDF might depend on their structural changes.It suggested that snail enzyme modifi cation could effectively improve physicochemical and functional properties of IDF and SDF from wheat bran.

对外负债与汇率暴跌风险:国际证据

本文使用31个国家2001—2013年的样本数据,对国家间双边对外负债如何影响双边汇率暴跌风险进行了分析。在控制了可能存在的内生性问题后,研究发现两国经济周期非对称性显著增加了汇率暴跌风险,一国对外负债的增加对汇率暴跌风险具有显著的抑制作用。一国金融发展水平的提高有助于减弱对外负债对汇率暴跌的抑制作用。进一步分析发现,对外负债对汇率暴跌的抑制作用在具有融资约束以及一国货币当局对外汇市场的干预程度较高的国家更为显著。

A highly active oxygen evolution electrocatalyst： Ultrathin CoNi double hydroxide/CoO nanosheets synthesized via interface-directed assembly

A cost-efficient and stable oxygen evolution electrocatalyst is essential for improving energy storage and conversion efficiencies. Herein, 2D nanosheets with randomly cross-linked CoNi layered double hydroxide （LDH） and small CoO nanocrystals were designed and synthesized via in situ reduction and interface- directed assembly in air. The formation of CoNi LDH/CoO nanosheets was attributed to the strong extrusion of hydrated metal-oxide clusters driven by the interfacial tension. The obtained loose and porous nanosheets exhibited low crystallinity due to the presence of numerous defects. Owing to the orbital hybridization between metal 3d and O 2p orbitals, and electron transfer between metal atoms through Ni-O-Co, a number of Co and Ni atoms in the CoNi LDH present a high ＋3 valency. These unique characteristics result in a high density of oxygen evolution reaction （OER） active sites, improving the affinity between OH- and catalyst, and resulting in a large accessible surface area and permeable channels for ion adsorption and transport. Therefore, the resulting nanosheets exhibited high catalytic activity towards the OER. The CoNi LDH/CoO featured a low onset potential of 1.48 V in alkaline medium, and required an overpotential of only 300 mV at a current density of 10 mA.cm-2, while displaying good stability in accelerated durability tests.

Co-vacancy-rich CO1-xS nanosheets anchored on rGO for high-efficiency oxygen evolution

Developing cost-efficient electrocatalysts for oxygen evolution is vital for the viability of H2 energy generated via electrolytic water. Engineering favorable defects on the electrocatalysts to provide accessible active sites can boost the sluggish reaction thermodynamics or kinetics. Herein, Col_xS nanosheets were designed and grown on reduced graphene oxide （rGO） by controlling the successive two-step hydrothermal reaction. A belt-like cobalt-based precursor was first formed with the assistance of ammonia and rGO, which were then sulfurized into Col_xS by L-cysteine at a higher hydrothermal temperature. Because of the non-stoichiometric defects and ultrathin sheet-like structure, additional cobalt vacancies （V^o） were formed/exposed on the catalyst surface, which expedited the charge diffusion and increased the electroactive surface in contact with the electrolyte. The resulting Col_xS/rGO hybrids exhibited an overpotential as low as 310 mV at 10 mA.cm-2 in an alkaline electrolyte for the oxygen evolution reaction （OER）. Density functional theory calculations indicated that the Vco on the Col_xS/rGO hybrid functioned as catalytic sites for enhanced OER. They also reduced the energy barrier for the transformation of intermediate oxygenated species, promoting the OER thermodynamics.

Hybridized triboelectric-electromagnetic nanogenerators and solar cell for energy harvesting and wireless power transmission

Energy harvesting and power transmission is a significant challenge for the self-powered technologies towards mobile electronic devices.Here,we propose a hybridized energy harvester to complement each other's strengths for simultaneously scavenging multiple types of energy and then wirelessly transmit the power.The harvester consists of electromagnetic-triboelectric nanogenerator units for collecting rotational energy and a commercial water-proof flexible solar cell.At a rotation rate of 500 rpm,the output current of electromagnetic-triboelectric nanogenerator units can reach about 630 mA through energy management.Moreover,the power harvested by hybridized energy harvester can be wirelessly transmitted up to a distance of about 100 cm in real time to charge mobile phone,anemometer,and hygrometer based on self-resonant coils.The hybridized energy harvester with wireless power transmission has potential applications in large-scale energy collection,long-distance wireless power transmission and sustainably driving mobile electronic devices.

Paper triboelectric nanogenerator designed for continuous reuse and quick construction

Along with the unceasing growth of worldwide economic and the associated issues on resources,energy and environment,clean energy generating technologies that are based on recyclable materials,if possible,may become the future trend of development.Here,we report the design of a cheap,lightweight,and recyclable single-electrode triboelectric nanogenerator(TENG)that utilizes waste paper as the triboelectric material.Under the current strategy,we successfully developed green energy machines without vastly increasing the mining of various critical minerals around the world.The as-designed TENG could not only collect and convert mechanical energy into electricity with sound efficiency,but also has the merit for continuous reuse and quick construction.The maximum output power density is as high as 171 mW·m^(-2) at a resistance of 130 MQ and could be integrated into a book for monitoring reading actions,thus providing a new approach to the low-cost,green and sustainable self-powered electronic systems.

Characterization of physicochemical properties,microbial diversity and volatile compounds of traditional fermented soybean paste in Henan province of China

This study aimed to investigate the changes in microbial diversity,and volatile compounds of traditional fermented soybean paste originated from Henan province of China using 16S rRNA sequencing,headspace solid phase microextraction-gas chromatography/mass spectrometry(HS-SPME-GC/MS),and electronic nose(E-nose).The amino acid nitrogen and reducing sugar contents ranged between 1.18 and 1.58 g/100 g and 2.29 and 3.74 mg/g,respectively.The results showed that fermented soybean paste exhibited the highest amount of glutamate and aspartate amino acids.Approximately 112 volatile compounds were detected in all SP samples comprising 10 alcohols,19 esters,10 acidic compounds,and 21 heterocyclic compounds.Furthermore,16S rRNA sequencing indicated that Enterobacter,Bacillus,Staphylococcus,and Enterococcus were the predominant bacteria in fermented soybean paste samples.Moreover,network analysis revealed that Klebsiella,Bacillus,and Lactobacillus positively correlated with H-fluorendimethyl,octenol,and benzaldehyde.These findings helped in understanding the formation of volatile flavoring compounds during SP fermentation.