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221.
Chenhao Zhang Shize Yang Jingjie Wu Mingjie Liu Sadegh Yazdi Muqing Ren Junwei Sha Jun Zhong Kaiqi Nie Almaz S. Jalilov Zhenyuan Li Huaming Li Boris I. Yakobson Qin Wu Emilie Ringe Hui Xu Pulickel M. Ajayan James M. Tour 《Liver Transplantation》2018,8(19)
Electrochemical reduction of CO2 provides an opportunity to reach a carbon‐neutral energy recycling regime, in which CO2 emissions from fuel use are collected and converted back to fuels. The reduction of CO2 to CO is the first step toward the synthesis of more complex carbon‐based fuels and chemicals. Therefore, understanding this step is crucial for the development of high‐performance electrocatalyst for CO2 conversion to higher order products such as hydrocarbons. Here, atomic iron dispersed on nitrogen‐doped graphene (Fe/NG) is synthesized as an efficient electrocatalyst for CO2 reduction to CO. Fe/NG has a low reduction overpotential with high Faradic efficiency up to 80%. The existence of nitrogen‐confined atomic Fe moieties on the nitrogen‐doped graphene layer is confirmed by aberration‐corrected high‐angle annular dark‐field scanning transmission electron microscopy and X‐ray absorption fine structure analysis. The Fe/NG catalysts provide an ideal platform for comparative studies of the effect of the catalytic center on the electrocatalytic performance. The CO2 reduction reaction mechanism on atomic Fe surrounded by four N atoms (Fe–N4) embedded in nitrogen‐doped graphene is further investigated through density functional theory calculations, revealing a possible promotional effect of nitrogen doping on graphene. 相似文献
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Jinbo Gao Wenjun Zhou Yuntong Liu Jing Zhu Liqing Sha Qinhai Song Hongli Ji Youxing Lin Xuehai Fei Xiaolong Bai Xiang Zhang Yun Deng Xiaobao Deng Guirui Yu Junhui Zhang Xunhua Zheng John Grace Yiping Zhang 《Ecosystems》2018,21(5):1013-1026
Litter inputs are expected to have a strong impact on soil N2O efflux. This study aimed to assess the effects of the litter decomposition process and nutrient efflux from litter to soil on soil N2O efflux in a tropical rainforest. A paired study with a control (L) treatment and a litter-removed (NL) treatment was followed for 2 years, continuously monitoring the effects of these treatments on soil N2O efflux, fresh litter input, decomposed litter carbon (LCI) and nitrogen (LNI), soil nitrate (NO3 ?–N), ammonium (NH4 +–N), dissolved organic carbon (DOC), and dissolved nitrogen (DN). Soil N2O flux was 0.48 and 0.32 kg N2O–N ha?1 year?1 for the L and NL treatments, respectively. Removing the litter caused a decrease in the annual soil N2O emission by 33%. The flux values from the litter layer were higher in the rainy season as compared to the dry season (2.10 ± 0.28 vs. 1.44 ± 0.35 μg N m?2 h?1). The N2O fluxes were significantly correlated with the soil NO3 ?–N contents (P < 0.05), indicating that the N2O emission was derived mainly from denitrification as well as other NO3 ? reduction processes. Suitable soil temperature and moisture sustained by rainfall were jointly attributed to the higher soil N2O fluxes of both treatments in the rainy season. The N2O fluxes from the L were mainly regulated by LCI, whereas those from the NL were dominated jointly by soil NO3 ? content and temperature. The effects of LCI and LNI on the soil N2O fluxes were the greatest in the 2 months after litter decomposition. Our results show that litter may affect not only the variability in the quantity of N2O emitted, but also the mechanisms that govern N2O production. However, further studies are still required to elucidate the impacting mechanisms of litter decomposition on N2O emission from tropical forests. 相似文献
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Solar‐induced chlorophyll fluorescence is strongly correlated with terrestrial photosynthesis for a wide variety of biomes: First global analysis based on OCO‐2 and flux tower observations 下载免费PDF全文
Xing Li Jingfeng Xiao Binbin He M. Altaf Arain Jason Beringer Ankur R. Desai Carmen Emmel David Y. Hollinger Alisa Krasnova Ivan Mammarella Steffen M. Noe Penélope Serrano Ortiz A. Camilo Rey‐Sanchez Adrian V. Rocha Andrej Varlagin 《Global Change Biology》2018,24(9):3990-4008
Solar‐induced chlorophyll fluorescence (SIF) has been increasingly used as a proxy for terrestrial gross primary productivity (GPP). Previous work mainly evaluated the relationship between satellite‐observed SIF and gridded GPP products both based on coarse spatial resolutions. Finer resolution SIF (1.3 km × 2.25 km) measured from the Orbiting Carbon Observatory‐2 (OCO‐2) provides the first opportunity to examine the SIF–GPP relationship at the ecosystem scale using flux tower GPP data. However, it remains unclear how strong the relationship is for each biome and whether a robust, universal relationship exists across a variety of biomes. Here we conducted the first global analysis of the relationship between OCO‐2 SIF and tower GPP for a total of 64 flux sites across the globe encompassing eight major biomes. OCO‐2 SIF showed strong correlations with tower GPP at both midday and daily timescales, with the strongest relationship observed for daily SIF at the 757 nm (R2 = 0.72, p < 0.0001). Strong linear relationships between SIF and GPP were consistently found for all biomes (R2 = 0.57–0.79, p < 0.0001) except evergreen broadleaf forests (R2 = 0.16, p < 0.05) at the daily timescale. A higher slope was found for C4 grasslands and croplands than for C3 ecosystems. The generally consistent slope of the relationship among biomes suggests a nearly universal rather than biome‐specific SIF–GPP relationship, and this finding is an important distinction and simplification compared to previous results. SIF was mainly driven by absorbed photosynthetically active radiation and was also influenced by environmental stresses (temperature and water stresses) that determine photosynthetic light use efficiency. OCO‐2 SIF generally had a better performance for predicting GPP than satellite‐derived vegetation indices and a light use efficiency model. The universal SIF–GPP relationship can potentially lead to more accurate GPP estimates regionally or globally. Our findings revealed the remarkable ability of finer resolution SIF observations from OCO‐2 and other new or future missions (e.g., TROPOMI, FLEX) for estimating terrestrial photosynthesis across a wide variety of biomes and identified their potential and limitations for ecosystem functioning and carbon cycle studies. 相似文献
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Lipases are physiologically important and ubiquitous enzymes that share a conserved domain and are classified into eight different families based on their amino acid sequences and fundamental biological properties. The Lipase3 family of lipases was reported to possess a canonical fold typical of α/β hydrolases and a typical catalytic triad, suggesting a distinct evolutionary origin for this family. Genes in the Lipase3 family do not have the same functions, but maintain the conserved Lipase3 domain. There have been extensive studies of Lipase3 structures and functions, but little is known about their evolutionary histories. In this study, all lipases within five plant species were identified, and their phylogenetic relationships and genetic properties were analyzed and used to group them into distinct evolutionary families. Each identified lipase family contained at least one dicot and monocot Lipase3 protein, indicating that the gene family was established before the split of dicots and monocots. Similar intron/exon numbers and predicted protein sequence lengths were found within individual groups. Twenty-four tandem Lipase3 gene duplications were identified, implying that the distinctive function of Lipase3 genes appears to be a consequence of translocation and neofunctionalization after gene duplication. The functional genes EDS1, PAD4, and SAG101 that are reportedly involved in pathogen response were all located in the same group. The nucleotide diversity (Dxy) and the ratio of nonsynonymous to synonymous nucleotide substitutions rates (Ka/Ks) of the three genes were significantly greater than the average across the genomes. We further observed evidence for selection maintaining diversity on three genes in the Toll-Interleukin-1 receptor type of nucleotide binding/leucine-rich repeat immune receptor (TIR-NBS LRR) immunity-response signaling pathway, indicating that they could be vulnerable to pathogen effectors. 相似文献
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Double sex and mab‐3 related transcription factor 1 regulates differentiation and proliferation in dairy goat male germline stem cells 下载免费PDF全文
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Xiao-Su Gu Fen Wang Cai-Yi Zhang Cheng-Jie Mao Jing Yang Ya-Ping Yang Sha Liu Li-Fang Hu Chun-Feng Liu 《Neurochemical research》2016,41(11):2923-2936
Paeoniflorin (PF) is the main active component extracted from the roots of Paeonialactiflora, a traditional Chinese medicine used for the treatment of neurodegenerative disorders, especially Parkinson’s disease (PD). The degeneration of dopaminergic (DA-) neurons in PD may be caused by pathological activation of acid-sensing ion channels (ASICs). Thus, we designed a series of experiments to evaluate the therapeutic effects of PF and to test whether its effects are related to its inhibitory effect on ASIC1a. We found that systemic administration of PF or ASICs blockers (psalmotoxin-1 and amiloride) improved behavioral symptoms, delayed DA-neuronal loss and attenuated the reduction of dopamine (DA) and its metabolites in a rat model of 6-hydroxydopamine (6-OHDA)-induced PD. In addition, our data showed that PF, like ASICs blockers, regulated the expression of ASIC1a, decreased the level of α-synuclein (α-SYN), and improved autophagic dysfunction. Further experiments showed that ASIC1a knockdown down-regulated the α-SYN level and alleviated the autophagic injury in the 6-OHDA-treated ASIC1a-silenced PC12 cells. In summary, these findings indicate that PF enhanced the autophagic degradation of α-SYN and, thus, protected DA-neurons against the neurotoxicity caused by 6-OHDA. These findings also provide experimental evidence that PF may be a neuroprotectant for PD by acting on ASIC1a and that ASIC1a may be involved in the pathogenesis of PD. 相似文献