Cobalt-doped tin disulfide catalysts for high-capacity lithium-air batteries with high lifetime.

Dual electrolyte lithium-air batteries have received widespread attention for their ultra-high energy density. However, the low internal redox efficiency of these batteries results in a relatively short operating life. SnS2 is widely used in Li-S batteries, Li-ion batteries, photocatalysis, and other fields due to the high discharge capacity in batteries. However, SnS2 suffers from low electrical conductivity and slow redox kinetics. In this study, Co-doped SnS2 is prepared by hydrothermal method for application in dual-electrolyte lithium-air batteries to study its electrochemical performance and its catalytic reaction process by DFT theory. Conductivity tests show that the Co doping enhances the electrical conductivity of the material and high transmission electron microscopy (HRTEM) results demonstrate that the Co doping of SnS2 increases the grain plane spacing and the material indicates that defects are created on the surface of the material, which is more beneficial to the electrochemical performance of the cell. Co-doped SnS2 exhibits excellent good cycling stability and high discharge capacity in a dual electrolyte lithium-air battery, maintaining a 0.7 V overpotential for 120 h at a current density of 0.1 mA cm-2, with a cell life of over 500 h and an initial discharge capacity showing excellent results up to 16 065 mA h g-1. In addition, this study explores the catalytic activity of Co-doped SnS2 based on density flooding theory (DFT). The results show that Co atoms have a synergistic effect with Sn atoms to perturb the lattice parameters. The calculations show that the catalytic activity is enhanced with the increasing of Co doping content and 3Co-Sn exhibits minimal overpotential.

Environmentally stable and stretchable polymer electronics enabled by surface-tethered nanostructured molecular-level protection.

Stretchable polymer semiconductors (PSCs) are essential for soft stretchable electronics. However, their environmental stability remains a longstanding concern. Here we report a surface-tethered stretchable molecular protecting layer to realize stretchable polymer electronics that are stable in direct contact with physiological fluids, containing water, ions and biofluids. This is achieved through the covalent functionalization of fluoroalkyl chains onto a stretchable PSC film surface to form densely packed nanostructures. The nanostructured fluorinated molecular protection layer (FMPL) improves the PSC operational stability over an extended period of 82 days and maintains its protection under mechanical deformation. We attribute the ability of FMPL to block water absorption and diffusion to its hydrophobicity and high fluorination surface density. The protection effect of the FMPL (~6 nm thickness) outperforms various micrometre-thick stretchable polymer encapsulants, leading to a stable PSC charge carrier mobility of ~1 cm2 V-1 s-1 in harsh environments such as in 85-90%-humidity air for 56 days or in water or artificial sweat for 42 days (as a benchmark, the unprotected PSC mobility degraded to 10-6 cm2 V-1 s-1 in the same period). The FMPL also improved the PSC stability against photo-oxidative degradation in air. Overall, we believe that our surface tethering of the nanostructured FMPL is a promising approach to achieve highly environmentally stable and stretchable polymer electronics.

Identification of Genetic Diversity, Pyrrocidine-Producing Strains and Transmission Modes of Endophytic Sarocladium zeae Fungi from Zea Crops.

Genotyping by sequencing (GBS) was used to reveal the inherent genetic variation within the haploid fungi Sarocladium zeae isolated from diverse Zea germplasm, including modern Zea mays and its wild progenitors-the teosintes. In accordance with broad host relationship parameters, GBS analysis revealed significant host lineages of S. zeae genetic diversity, indicating that S. zeae genetic variation may associate with different evolutionary histories of host species or varieties. Based on a recently identified PKS-NRPS gene responsible for pyrrocidine biosynthesis in S. zeae fungi, a novel PCR assay was developed to discriminate pyrrocidine-producing S. zeae strains. This molecular method for screening bioactive strains of S. zeae is complementary to other approaches, such as chemical analyses. An eGFP-labelled S. zeae strain was also developed to investigate the endophytic transmission of S. zeae in Z. mays seedlings, which has further improved our understanding of the transmission modes of S. zeae endophytes in maize tissues.

Coexistence of silver ion and tetracycline at environmentally relevant concentrations greatly enhanced antibiotic resistance gene development in activated sludge bioreactor.

Antibiotic resistance has become a global public health problem. Recently, various environmental pollutants have been reported to induce the proliferation of antibiotic resistance. However, the impact of multiple pollutants (e.g., heavy metals and antibiotics), which more frequently occur in practical environments, is poorly understood. Herein, one widely distributed heavy metal (Ag+) and one frequently detected antibiotic (tetracycline) were chosen to investigate their coexisting effect on the proliferation of antibiotic resistance in the activated sludge system. Results show that the co-occurrence of Ag+ and tetracycline at environmentally relevant concentrations exhibited no distinct inhibition in reactor performances. However, they inhibited the respiratory activity by 42%, destroyed the membrane structure by 218%, and increased membrane permeability by 29% compared with the blank control bioreactor. Moreover, the relative abundances of target antibiotic resistance genes (ARGs) (e.g., tetA, blaTEM-1, and sulII) in effluent after exposure of coexisting Ag+ and tetracycline were increased by 92-1983% compared with those in control reactor, which were 1.1-4.3 folds higher than the sum of the sole ones. These were possibly attributed to the enrichments of antibiotic-resistant bacteria. The results would illumine the coexisting effect of heavy metals and antibiotics on the dissemination of ARGs in activated sludge system.

In Situ Electrochemical Fabrication of Ultrasmall Ru-Based Nanoparticles for Robust N2H4 Oxidation.

Ultrasmall Ru nanoparticles is expected as a potential alternative to Pt for efficient hydrazine oxidation (HzOR). However, preparation of ultrasmall and well-distributed Ru nanoparticles usually suffered from the steps of modification of supports, coordination, reduction with strong reducing reagents (e.g., NaBH4) or pyrolysis, imposing the complexity. Based on the self-reducibility of C-OH group and physical adsorption ability of commercial Ketjen black (KB), we developed an efficient, stable and robust Ru-based electrocatalyst (A-Ru-KB) by coupling impregnation of KB in RuCl3 solution and simple in situ electrochemical activation strategy, which endowed the formation of ultrasmall and well-distributed Ru nanoparticles. Benefiting from an enhanced exposure of Ru sites and the faster mass transport, A-Ru-KB achieved 63.4 and 3.9-fold enhancements of mass activity compared with Pt/C and Ru/C, respectively, accompanied by a ∼144 mV lower onset potential and faster catalytic kinetics than Pt/C. In the hydrazine fuel cell, the open-circuit voltage and maximal mass power density of A-Ru-KB was 130 mV and ∼3.8-fold higher than those of Pt/C, respectively, together with the long-term stability. This work would provide a facile and sustainable approach for large-scale production of other robust metal (electro)catalysts with ultrasmall nanosize for various energy conversion and electrochemical organic synthesis.

Integrated measurement of intracellular proteins and transcripts in single cells.

Biological function arises from the interplay of proteins, transcripts, and metabolites. An ongoing revolution in miniaturization technologies has created tools to analyze any one of these species in single cells, thus resolving the heterogeneity of tissues previously invisible to bulk measurements. An emerging frontier is single cell multi-omics, which is the measurement of multiple classes of analytes from single cells. Here, we combine bead-based transcriptomics with microchip-based proteomics to measure intracellular proteins and transcripts from single cells and defined small numbers of cells. The transcripts and proteins are independently measured by sequencing and fluorescent immunoassays respectively, to preserve their optimal measurement modes, and linked by encoding the physical address locations of the cells into digital sequencing space using spatially patterned DNA barcodes. We resolve cell-type-specific protein and transcript signatures and present a path forward to scaling the platform to high-throughput.

Does gibberellin biosynthesis play a critical role in the growth of Lolium perenne? Evidence from a transcriptional analysis of gibberellin and carbohydrate metabolic genes after defoliation.

Global meat and milk production depends to a large extent on grazed pastures, with Lolium perenne being the major forage grass in temperate regions. Defoliation and subsequent regrowth of leaf blades is a major and essential event with respect to L. perenne growth and productivity. Following defoliation, carbohydrates (mainly fructans and sucrose) have to be mobilized from heterotrophic tissues to provide energy and carbon for regrowth of photosynthetic tissues. This mobilization of reserve carbohydrates requires a substantial change in the expression of genes coding for enzymes involved in carbohydrate metabolism. Here we tested the hypothesis that gibberellins (GA) are at the core of the processes regulating the expression of these genes. Thus, we examined the transcript profiles of genes involved in carbohydrate and GA metabolic pathways across a time course regrowth experiment. Our results show that following defoliation, the immediate reduction of carbohydrate concentrations in growing tissues is associated with a concomitant increase in the expression of genes encoding carbohydrate mobilizing invertases, and was also associated with a strong decrease in the expression of fructan synthesizing fructosyltransferase genes. We also show that the decrease in fructan levels is preceded by increased expression of the GA activating gene GA 3-oxidase and decreased expression of the GA inactivating gene GA 2 -oxidase in sheaths. GA 3-oxidase expression was negatively, while GA 2 -oxidase positively linked to sucrose concentrations. This study provides indicative evidence that gibberellins might play a role in L. perenne regrowth following defoliation and we hypothesize that there is a link between gibberellin regulation and sugar metabolism in L. perenne.

Transcript profiling of fructan biosynthetic pathway genes reveals association of a specific fructosyltransferase isoform with the high sugar trait in Lolium perenne.

Lolium perenne cultivars with elevated levels of fructans in leaf blades (high sugar-content grasses) have been developed to improve animal nutrition and reduce adverse environmental impacts of pastoral agricultural systems. Expression of the high sugar trait can vary substantially depending on genotype×environment (G×E) interactions. We grew three potential high sugar-content and a control cultivar in three temperature regimes and quantified water soluble carbohydrates (WSCs) and the expression of all functionally characterised L. perenne fructan pathway genes in leaf tissues. We also analysed the distribution, expression and sequence variation of two specific isoforms of Lp6G-FFT (fructan: fructan 6G-fructosyltransferase). Our study confirmed a significant G×E interaction affecting the accumulation of fructans in the high sugar-content cultivar AberDart, which accumulated higher levels of high DP (degree of polymerisation) fructans in blades compared to the control cultivar only when grown at 20°C (day)/10°C (night) temperatures. The cultivar Expo on the other hand accumulated significantly higher levels of high DP fructans in blades independent of temperature. Fructan levels in pseudostems were higher than in blades, and they increased markedly with decreasing temperature, but there was no consistent effect of cultivar in this tissue. The expression of the high sugar trait was generally positively correlated with transcript levels of fructosyltransferases. Presence and expression of only one of the two known 6G-FFT isoforms was positively correlated with high fructan biosynthesis, while the second isoform was associated with low fructan concentrations and positively correlated with fructan exohydrolase gene expression. The presence of distinct 6G-FFT sequence variants appears to be associated with the capacity of high sugar-content grasses to accumulate higher fructan levels particularly at warmer temperatures. These findings might be exploited for the selection and breeding of 'warm-effective' high sugar-content grasses to overcome some of the limitations of current high sugar-content ryegrass cultivars.

Transcriptional regulation of phosphate transporters from Lolium perenne and its mycorrhizal symbionts in response to phosphorus supply.

Phosphate (P) uptake is critical for plant growth, but to date little is known about P uptake and transport in the pasture grass Lolium perenne L. We have identified a putative P transporter (PT) from L. perenne mycorrhizal roots (LpPT1) and assessed its transcriptional regulation by soil P availability and mycorrhizal colonisation. We also investigated transcript levels of fungal PTs from the two arbuscular mycorrhizal species Rhizophagus intraradices and Funneliformis mosseae. Our analyses indicated that LpPT1 codes for a high affinity PT most likely responsible for direct P uptake from the soil. LpPT1 is highly expressed in roots of plants grown at low P, whereas high P repressed its expression. LpPT1 was not expressed in above-ground plant tissues. Colonisation with R. intraradices did not affect expression of LpPT1 significantly. Transcript levels of the R. intraradices PT were not affected by P availability but the F. mosseae PT was repressed by high P supply, particularly in intraradical hyphae. Our study could assist in deciphering the molecular mechanisms of P uptake in the pasture grass L. perenne.

Functional characterisation and transcript analysis of an alkaline phosphatase from the arbuscular mycorrhizal fungus Funneliformis mosseae.

Alkaline phosphatases (ALP) in arbuscular mycorrhizal (AM) fungi have been suggested to be involved in transfer of phosphate from the mycorrhizal fungus to the host plant, but exact mechanisms are still unknown, partially due to the lack of molecular information. We isolated a full-length cDNA (FmALP) from the AM fungus Funneliformis mosseae (syn. Glomus mosseae) showing similarity with putative ALP genes from Rhizophagus intraradices (syn. Glomus intraradices) and Gigaspora margarita. For functional characterisation FmALP was expressed heterologously in the yeast Pichia pastoris. The recombinant FmALP protein had a pH optimum of 9.5, and catalysed the hydrolysis of glycerolphosphate and, to a lesser extent of glucose-1- and 6-phosphate, confirming it to be an alkaline phosphatase belonging to the family of alkaline phosphomonoesterases (EC 3.1.3.1). FmALP did not catalyse the hydrolysis of ATP or polyP. Relative FmALP transcript levels were analysed in intra- and extraradical hyphae isolated from F. mosseae infected ryegrass (Lolium perenne) using reverse transcription-quantitative polymerase chain reaction (RT-qPCR). FmALP was highly expressed in intraradical hyphae at low P(i) supply, and its expression was repressed by high P(i) supply. Taken together this study provides evidence for mycorrhizal alkaline phosphatases playing a role in P mobilisation from organic substrates under P starvation conditions.

One-step hydrotreatment of vegetable oil to produce high quality diesel-range alkanes.

A one-step hydrotreatment of vegetable oil combining deoxygenation and isomerization to directly produce low cloud point, high quality diesel is devised. The Pt/zeolite bifunctional catalysts prepared by using SAPO-11 and ZSM-22 zeolites as supports are used in this process. Catalytic reactions are conducted in a fixed-bed reactor under a hydrogen atmosphere. Over the bifunctional catalyst, 100 % conversion of soybean oil is obtained at 357 °C, 4 MPa, and 1 h(-1), and 80 % organic liquid yield is achieved, which is close to the maximum theoretical liquid yield. In the organic products, the alkanes selectivity is 100 % with an i-alkanes selectivity above 63 %. NH(3)-temperature programmed desorption (TPD), pyridine IR spectroscopy, and other characterization techniques are used to study the effect of the support acidity on the reaction pathway. Over the Pt/zeolite bifunctional catalyst with less strong Lewis acid sites, the reaction proceeds via the decarboxylation plus decarbonylation pathway. This one-step method provides a new strategy to produce low cloud point, high quality diesel from biomass feedstock in a more economic and attractive way.