1,295 research outputs found
End water content determines the magnitude of N2O pulse from nitrifier denitrification after rewetting a fluvo-aquic soil
No full textLarge nitrous oxide (N2O) emissions pulses have been observed after rewetting dry soil. However, few studies have uncoupled the effects of drought severity from the degree to which the soil is saturated. In this study, we conducted three aerobic incubation experiments to investigate the effects of soil rewetting on N2O emissions from a dryland soil. The results showed that, at constant soil moisture, total N2O emissions in soil with 90% water-holding capacity (WHC) were significantly higher than those in 30%, 45%, 60% and 75% WHC treatments. In the dry–wet group, the soil moisture content was adjusted from 30%, 45% and 60% WHC to the end content of 75% and 90% WHC, respectively; the cumulative N2O emissions in the 30–90%, 45–90% and 60–90% WHC nitrogen (N) treatments were significantly higher than those in the 30–75%, 45–75% and 60–75% WHC N treatments. Regarding fertilizer N types, there was no significant difference in N2O emissions from soil at 90% WHC when (NH4)2SO4 or urea was applied. Nitrification inhibitor significantly reduced N2O emissions in soil applied with NH4+-N fertilizer, indicating that nitrification played a major role in N2O emissions from soils. The contribution of denitrification was negligible, according to the low emission rate of soils with only NO3− additions. High N2O emissions occurred in soil treated with NO2−, accounting for about 83.6% of those of the NH4+ treatment. Therefore, in this study we concluded that the end water content of soil was more important than the role of drought severity in the dry-wet process and that nitrifier denitrification was probably the main pathway of N2O production under the condition of 90% WHC moisture after rewetting soil
Orography‐induced atmospheric small‐scale waves during Bora using lidar observations and numerical simulations
No full textAtmospheric flow of cold air over mountain barriers in the Alpine region often gives a rise to
strong and gusty downslope wind, Bora. Such flows are often accompanied by atmospheric waves, generated by the flow passing an elevated barrier. Such phenomenon can only rarely be observed visually and can generally not be reliably reproduced by simplified numerical models. Orography‐induced atmospheric small‐scale waves were experimentally observed on 25 January 2019 during a Bora outbreak in the Vipava valley, Slovenia. A vertical scanning lidar, positioned at the lee side of the Trnovski gozd mountain and a fixed direction lidar, 5 km apart in the Vipava valley, were used to characterize the density field. The flow exhibited a stationary jump after the mountain ridge and, superimposed, an oscillatory flow pattern. High‐resolution numerical simulations complemented the observations and supported experimental results on the flow periodicity but also on the wave structures and propagation characteristics
Steam reforming of biomass raw fuel gas over NiO-MgO solid solution cordierite monolith catalyst
No full textThe NiO-MgO solid solution cordierite monolith catalyst was prepared by impregnation. 60 h steam reforming tests were carried out at 1023 K TC was used to analyze the carbon deposition on the catalyst. GC and GC-MS were used to analyze the component of biomass fuel gas and tar. The results show that steam reforming can effectively improve the quality of fuel gas, H(2)/CO ratio can be adjusted by steam reforming, The addition of steam can also increase the activity and stability of the catalyst dramatically. The CH(4) conversion reached 94%. TG shows that the addition of steam can decrease the carbon deposition on the catalyst. GC-MS result shows that most of the tar was converted to H(2), CO and trace lighter component. Steam reforming can eliminate the biomass tar species more deeply than dry reforming. (C) 2009 Elsevier Ltd. All rights reserved
Aqueous-phase catalytic process for production of pentane from furfural over nickel-based catalysts
No full textSupported nickel catalysts for aqueous-phase catalytic hydrogenation/dehydration of furfural were prepared using impregnation method with different supporting materials. Effects of supporting materials, nickel loading and reaction temperature on conversion rate of furfural as well as selectivity for desired product C(5) were systematically studied. Experiments showed that catalytic activity of Ni/SiO(2)-Al(2)O(3) was obviously higher than that of Ni/gamma-Al(2)O(3). The conversion of furfural over 14 wt.%Ni/SiO(2)-Al(2)O(3) catalyst was 62.99% under the temperature of 140 degrees C and the cold pressure of H(2) 3.0 MPa, while that was 19.19% over 14 wt.%Ni/gamma-Al(2)O(3) under the same conditions. Conversion rate of furfural increased with temperature, but selectivity for desired product decreased with temperature. Tentative reaction mechanisms of hydrogenation/dehydration were proposed. In order to investigate catalyst recyclability, a batch of Ni/SiO(2)-Al(2)O(3) was reused three times and analyzed by Thermogravimetry (TG). It was found that considerable amount of coke formed on Ni/SiO(2)-Al(2)O(3) surface and deteriorated its activity dramatically after second use. (C) 2010 Elsevier Ltd. All rights reserved
Direct Selective Hydrogenation of Phenol and Derivatives over Polyaniline-Functionalized Carbon-Nanotube-Supported Palladium
No full textInvited for this months cover are the groups of Prof. Jinzhu Chen and Prof. Longlong Ma from the Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences. The image shows a bifunctional stabilizing mechanism of the composite support PANI/CNT on palladium nanoparticles in the catalyst PdPANI/CNT, and how the PANI/CNT can play a role in controlling the conversion and selectivity in the direct hydrogenation of phenol to cyclohexanone
A review of thermal-chemical conversion of lignocellulosic biomass in China
No full text
Biomass, a renewable, sustainable and carbon dioxide neutral resource, has received widespread attention in the energy market as an alternative to fossil fuels. Thermal-chemical conversion of biomass to produce biofuels is a promising technology with many commercial applications. This paper reviewed the state-of-the-art research and development of thermal-chemical conversion of biomass in China with a special focus on gasification, pyrolysis, and catalytic transformation technologies. The advantages and disadvantages, potential of future applications, and challenges related to these technologies are discussed. Conclusively, these transformation technologies for the second-generation biofuels with using non-edible lignocellulosic biomass as feedstocks show prosperous perspective for commercial applications in near future. (C) 2012 Elsevier Inc. All rights reserved.</p
Upgrading of fast pyrolysis liquid fuel from biomass over Ru/gamma-Al2O3 catalyst
No full text
Biomass is one of the important renewable energy. More attention has been paid on conversion of biomass and the upgrading of its products. In this paper, the bio-oil was prepared by pyrolysis of pine sawdust in fast pyrolysis installation. A series of ruthenium catalysts were prepared for the upgrading of bio-oil. The catalytic activity was evaluated by the reaction of the model compound (acetic acid) under 3 MPa hydrogen pressure. The effects of Ru-loading and second metal addition on the catalytic activity were investigated. The 0.5Ru/gamma-Al2O3 catalyst with 0.5%Co addition exhibited the highest activity, giving the highest conversion of acetic acid (30.98%). After upgrading over this catalyst, the properties of the pyrolysis bio-oil were improved. The content of the esters increased by 2-fold in the upgraded oil than in the raw one. The GC-MS spectrometry analysis showed that not only the hydrogenation but also the esterification happened in the bio-oil over the CoRu/gamma-Al2O3 catalyst. Results indicate that it is possible to improve the properties of bio-oil by hydrotreating and esterifying carboxyl groups. (C) 2011 Elsevier Ltd. All rights reserved.</p
Biochemical analysis of HDAC6-mediated Influenza A virus uncoating and its targeting by small artificial proteins
No full textHDAC6 is a member of the histone deacetylases (HDACs) family and has a unique structure, with tandem catalytic domains and a conserved ubiquitin (Ub)-binding zinc finger (ZnF) domain. While the deacetylase activity is important for cell motility, stress response, cancer progression, among others, HDAC6 function also depends on its ZnF domain which engages Ub in many cases. For example, it is important for the formation of cellular granules, such as aggresome and stress granules. In particular, the aggresome/HDAC6 pathway can be hijacked by exogenous pathogens, like influenza A virus (IAV), to facilitate the infection: the HDAC6 ZnF domain is indispensable for virion uncoating, but the molecular details are still missing.
The goal of this thesis has been (i) to gain additional details about the cellular components recruited by the HDAC6 ZnF domain and involved in the viral uncoating and (ii) to use small artificial proteins to interfere with this recruitment.
Analysis by immunoprecipitations and biochemical assays allowed me to show that the recruitment of Ub by the HDAC6 ZnF is essential to allow the formation of a complex involving components of the actomyosin system, in particular myosin 10 and actin. Unanchored Ub chains form a bridge between HDAC6 and myosin 10. This also has an impact on the recruitment of another motor system, dynein: recruitment of dynein by HDAC6 is increased when Ub cannot be recruited. These biochemical data were combined with mathematical analysis of the system by our colleagues at D-BSSE, to model the uncoating of IAV. This allowed developing a tug-of-war model of uncoating which realistically depicts the biological observations. Besides, results from clinical samples could be obtained; in particular, two IAV strains, H1N1 and H3N2, show a different dependency on the HDAC6/aggresome pathway. We could show that this relates to their M1 matrix protein having different affinities (H1N1 > H3N2) for interaction with HDAC6. This information could also be integrated into the model and allowed to further refine it (Arctibasova*, Wang* et al., submitted).
Above we demonstrated the importance of HDAC6 ZnF-Ub interaction during IAV infection, we decided to target this protein-protein interaction, as it might be valuable therapeutically. To achieve this, we screened out multiple DARPins (Designed Ankyrin Repeat Proteins) which bind specifically to HDAC6 ZnF. One of the DARPins, F10, could be shown to efficiently block the HDAC6-Ub interaction by in vitro pull-down and split-GFP assays in cells. X-ray crystallographic data (with a resolution of 2.55 Å) showed that F10 occupies the pocket where Ub engages. We established cell lines for expression and conditional degradation of DARpin F10; this allowed us to show that IAV infection is greatly inhibited by F10 expression. Investigation of IAV M1 protein release by microscopy convinced us that the uncoating step is interrupted. Furthermore, we showed that another RNA virus, ZIKA, is also impaired by DARPin F10. Other cellular pathways, like aggresome and stress granule formation, are inhibited as well (Wang et al., submitted). Considering that stress granule and aggresome are both potentially pathological granules in neurodegenerative diseases (e.g. Amyotrophic lateral sclerosis and Parkinson diseases), we have shown that the HDAC6 ZnF domain is a targetable site for drug discovery, with potential for patients who are suffering from severe virus infection or as neurodegenerative diseases
- …
