Abstract
Stabilizing active sites of non-iridium-based oxygen evolution reaction (OER) electrocatalysts is crucial, but remains a big challenge for hydrogen production by acidic water splitting. ...Here, we report that non-stoichiometric Ti oxides (TiO
x
) can safeguard the Ru sites through structural-confinement and charge-redistribution, thereby extending the catalyst lifetime in acid by 10 orders of magnitude longer compared to that of the stoichiometric one (Ru/TiO
2
). By exploiting the redox interaction-engaged strategy, the in situ growth of TiO
x
on Ti foam and the loading of Ru nanoparticles are realized in one step. The as-synthesized binder-free Ru/TiO
x
catalyst exhibits low OER overpotentials of 174 and 265 mV at 10 and 500 mA cm
−2
, respectively. Experimental characterizations and theoretical calculations confirm that TiO
x
stabilizes the Ru active center, enabling operation at 10 mA cm
−2
for over 37 days. This work opens an avenue of using non-stoichiometric compounds as stable and active materials for energy technologies.
Non-noble-metal electrocatalysts of transition metal phosphides have been considered as promising catalysts for hydrogen evolution reaction (HER); however, their bifunctional catalytic activities are ...limited by unsatisfactory performance in oxygen evolution reaction (OER). Here we report ultrathin amorphous CoFeP nanosheets derived from CoFe layered double hydroxides (LDHs) as bifunctional electrocatalysts with a simple phosphorization method. The partial phosphating induced by sodium hypophosphite can greatly reduce the thickness of nanosheets and promote the polycrystalline nature of the materials, leading to more active sites exposed and faster electronic transport. The optimal levels of phosphating agents are 1.8 g for OER and 2.4 g for HER, respectively, etched by which the resultant CoFeP materials can exhibit excellent electrocatalytic performances toward OER, HER and overall water splitting in alkaline media. At the current densities of 100 and 20 mA cm−2, ultralow overpotentials of 242 and 80 mV are achieved for OER and HER, individually, which are 128 mV lower than RuO2 and 6 mV slightly lower than Pt, respectively. In a cell voltage of 1.62 V, the CoFeP materials reacted with 1.8 and 2.4 g phosphating agents and used as the anode and the cathode, respectively, can achieve 100 mA cm−2 current density and exhibit extraordinary durability for 30 h in overall water splitting. These superior electrocatalytic properties of ultrathin amorphous CoFeP nanosheets are comparable to those of state-of-the-art noble metal and other reported catalysts for OER, HER and overall water splitting. This work proposes a promising strategy for excellent bifunctional electrocatalysts by tailoring the morphology and crystallinity degree based on LDHs through a facile partial phosphating method.
Partial phosphating was applied to synthesize ultrathin amorphous CoFeP nanosheets as bifunctional electrocatalyst with ultralow potential at high current density. Display omitted
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Bubble-mediated methane (CH4) released from the highly polluted Dalian Bay in China and its effect on the distribution of atmospheric CH4 were observed in summer of 2016. The determined components in ...bubble sample included CH4, carbon dioxide (CO2), nitrous oxide (N2O) and water vapor, etc. Tidal movement was the dominant factor regarding the bubble release rate. The mole fraction of CH4 in the bubbles reached 0.378 mol mol−1, resulting in an ejective flux of 73.52 mmol m−2 d−1, which was 14.8 times of diffusive flux, and probably induce a direct effects on the horizontal and vertical mole fraction distribution of local atmospheric CH4. Thus, bubble-mediated CH4 release from polluted coastal seas is a hot-spot for CH4 emissions, and predominantly caused by long-term human activities.
•Components in bubbles released from the highly polluted Dalian Bay included CH4, CO2, N2O, and water vapor, etc.•The dominant factor affecting the bubble release rate was tidal movements in summer.•The mole fraction of CH4 in bubbles reached 0.378 mol mol−1.•The sea-to-air CH4 flux of bubble ebullition was 14.8 times of diffusive flux.•The distribution of CH4 in boundary air could be influenced directly by bubble-mediated CH4.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Peroxyacetyl nitrate (PAN), a major secondary pollutant in the atmosphere, has received much concern for its particular importance in atmospheric chemistry and adverse effects on human and plants. ...Atmospheric PAN and PPN were measured by using a gas chromatograph equipped with electron capture detector (GC-ECD) from June to September 2010, and the source and major sink for PAN were firstly studied in Beijing. The distinct diurnal variations of PAN and PPN with maximum in the afternoon were observed, and the mean and maximum values were 2.61 ± 2.57 ppbv (N = 839) and 12.5 ppbv for PAN and 0.52 ± 0.38 ppbv (N = 152) and 2.16 ppbv for PPN during the measuring period, respectively. Good correlation (R = 0.85) between PAN and PPN with a slope (ΔPPN/ΔPAN) of 0.134 indicated that anthropogenic volatile organic compounds (AVOCs) dominated the photochemical formation of PANs in Beijing. Further, we found acetaldehyde was the predominant carbonyl precursor of PAN with the contribution of 59.7% to the total peroxyacetyl (PA) radical. Methyl glyoxal, methacrolein, acetone, methyl vinyl ketone, and biacetyl contributed 7.1%, 8.8%, 19.7%, 3.4%, and 1.3% to total PA radical, respectively. Anti-correlation between PAN concentrations and the NO/NO2 ratios was found during the whole investigating period. In addition, the amount of PAN lost by thermal decomposition (TPAN) accounted for remarkable fractions of PAN observed under high temperature during both daytime and nighttime.
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•Atmospheric PANs were measured by using GC-ECD during summertime in Beijing.•High pollution levels of PAN and PPN were found.•Acetaldehyde was the predominant precursor of PAN in the investigating period.•Thermal decomposition of PAN played an important role in its chemical process.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Diet is a key player in gut-liver axis. However, the effect of different dietary patterns on gut microbiota and liver functions remains unclear. Here, we used rodent standard chow and purified diet ...to mimic two common human dietary patterns: grain and plant-based diet and refined-food-based diet, respectively and explored their impacts on gut microbiota and liver. Gut microbiota experienced a great shift with notable increase in Desulfovibrio, gut bile acid (BA) levels elevated significantly, and liver inflammation was observed in mice fed with the purified diet. Liver inflammation and elevated gut BA levels also occurred in mice fed with the chow diet after receiving Desulfovibrio desulfuricans ATCC 29,577 (DSV). Restriction of sulfur-containing amino acids (SAAs) prevented liver injury mainly through higher hepatic antioxidant and detoxifying ability and reversed the elevated BA levels due to excess Desulfovibrio. Ex vivo fermentation of human fecal microbiota with primary BAs demonstrated that DSV enhanced production of secondary BAs. Higher concentration of both primary and secondary BAs were found in the gut of germ-free mice after receiving DSV. In conclusion, Restriction of SAAs in diet may become an effective dietary intervention to prevent liver injury associated with excess Desulfovibrio in the gut.Diet is a key player in gut-liver axis. However, the effect of different dietary patterns on gut microbiota and liver functions remains unclear. Here, we used rodent standard chow and purified diet to mimic two common human dietary patterns: grain and plant-based diet and refined-food-based diet, respectively and explored their impacts on gut microbiota and liver. Gut microbiota experienced a great shift with notable increase in Desulfovibrio, gut bile acid (BA) levels elevated significantly, and liver inflammation was observed in mice fed with the purified diet. Liver inflammation and elevated gut BA levels also occurred in mice fed with the chow diet after receiving Desulfovibrio desulfuricans ATCC 29,577 (DSV). Restriction of sulfur-containing amino acids (SAAs) prevented liver injury mainly through higher hepatic antioxidant and detoxifying ability and reversed the elevated BA levels due to excess Desulfovibrio. Ex vivo fermentation of human fecal microbiota with primary BAs demonstrated that DSV enhanced production of secondary BAs. Higher concentration of both primary and secondary BAs were found in the gut of germ-free mice after receiving DSV. In conclusion, Restriction of SAAs in diet may become an effective dietary intervention to prevent liver injury associated with excess Desulfovibrio in the gut.
Current tools used in the reconstruction of ancestral gene orders often fall into event-based and adjacency-based methods according to the principles they follow. Event-based methods such as GRAPPA ...are very accurate but with extremely high complexity, while more recent methods based on gene adjacencies such as InferCARsPro is relatively faster, but often produces an excessive number of chromosomes. This issue is mitigated by newer methods such as GapAdj, however it sacrifices a considerable portion of accuracy. We recently developed an adjacency-based method in the probabilistic framework called PMAG to infer ancestral gene orders. PMAG relies on calculating the conditional probabilities of gene adjacencies that are found in the leaf genomes using the Bayes' theorem. It uses a novel transition model which accounts for adjacency changes along the tree branches as well as a re-rooting procedure to prevent any information loss. In this paper, we improved PMAG with a new method to assemble gene adjacencies into valid gene orders, using an exact solver for traveling salesman problem (TSP) to maximize the overall conditional probabilities. We conducted a series of simulation experiments using a wide range of configurations. The first set of experiments was to verify the effectiveness of our strategy of using the better transition model and re-rooting the tree under the targeted ancestral genome. PMAG was then thoroughly compared in terms of three measurements with its four major competitors including InferCARsPro, GapAdj, GASTS and SCJ in order to assess their performances. According to the results, PMAG demonstrates superior performance in terms of adjacency, distance and assembly accuracies, and yet achieves comparable running time, even all TSP instances were solved exactly. PMAG is available for free at http://phylo.cse.sc.edu.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Gene order changes, under rearrangements, insertions, deletions and duplications, have been used as a new type of data source for phylogenetic reconstruction. Because these changes are rare compared ...to sequence mutations, they allow the inference of phylogeny further back in evolutionary time. There exist many computational methods for the reconstruction of gene-order phylogenies, including widely used maximum parsimonious methods and maximum likelihood methods. However, both methods face challenges in handling large genomes with many duplicated genes, especially in the presence of whole genome duplication.
In this paper, we present three simple yet powerful methods based on maximum-likelihood (ML) approaches that encode multiplicities of both gene adjacency and gene content information for phylogenetic reconstruction.
Extensive experiments on simulated data sets show that our new method achieves the most accurate phylogenies compared to existing approaches. We also evaluate our method on real whole-genome data from eleven mammals. The package is publicly accessible at http://www.geneorder.org .
Our new encoding schemes successfully incorporate the multiplicity information of gene adjacencies and gene content into an ML framework, and show promising results in reconstruct phylogenies for whole-genome data in the presence of massive duplications.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Ulcerative colitis (UC), one of the typical inflammatory bowel diseases caused by dysregulated immunity, still requires novel therapeutic medicine with high efficacy and low toxicity.
has been widely ...used to treat different health problems especially gastrointestinal sickness in China for thousands of years. Here, we isolated, purified, and characterized a novel low weight polysaccharide (HEP10, Mw: 9.9 kDa) from the mycelia of
in submerged culture. We explored the therapeutic effect of HEP10 on UC and explored its underlying mechanisms. On one hand, HEP10 suppressed the production of TNF-α, IL-1β, IL-6, inducible iNOS, and COX-2 in LPS challenged murine macrophage RAW264.7 cells, as well as in colons from DSS-induced colitis mice. On the other hand, HEP10 treatment markedly suppressed the activation of NLRP3 inflammasome, NF-κB, AKT, and MAPK pathways. Moreover, HEP10 reversed DSS-induced alternation of the gut community composition and structure by significantly increasing
and also promoting functional shifts in gut microbiota. Structural equation modeling also highlighted that HEP10 can change widely through gut microbiota. In conclusion, HEP10 has a better prebiotic effect than the crude polysaccharides of
, which can be used as a novel dietary supplement and prebiotic to ameliorate colitis.
Changes of gene orderings have been extensively used as a signal to reconstruct phylogenies and ancestral genomes. Inferring the gene order of an extinct species has a wide range of applications, ...including the potential to reveal more detailed evolutionary histories, to determine gene content and ordering, and to understand the consequences of structural changes for organismal function and species divergence. In this study, we propose a new adjacency-based method, PMAG + , to infer ancestral genomes under a more general model of gene evolution involving gene insertions and deletions (indels), in addition to gene rearrangements. PMAG + improves on our previous method PMAG by developing a new approach to infer ancestral gene contents and reducing the adjacency assembly problem to an instance of TSP. We designed a series of experiments to extensively validate PMAG + and compared the results with the most recent and comparable method GapAdj. According to the results, ancestral gene contents predicted by PMAG + coincides highly with the actual contents with error rates less than 1 percent. Under various degrees of indels, PMAG + consistently achieves more accurate prediction of ancestral gene orders and at the same time, produces contigs very close to the actual chromosomes.
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