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1.
Bouchard LS Burt SR Anwar MS Kovtunov KV Koptyug IV Pines A 《Science (New York, N.Y.)》2008,319(5862):442-445
Catalysis is vital to industrial chemistry, and the optimization of catalytic reactors attracts considerable resources. It has proven challenging to correlate the active regions in heterogeneous catalyst beds with morphology and to monitor multistep reactions within the bed. We demonstrate techniques, using magnetic resonance imaging and para-hydrogen (p-H2) polarization, that allow direct visualization of gas-phase flow and the density of active catalyst in a packed-bed microreactor, as well as control over the dynamics of the polarized state in space and time to facilitate the study of subsequent reactions. These procedures are suitable for characterizing reactors and reactions in microfluidic devices where low sensitivity of conventional magnetic resonance would otherwise be the limiting factor. 相似文献
2.
The objectives of our study were to quantify the impact of endogeic earthworms Aporrectodea caliginosa (Savigny) on iron (Fe), manganese (Mn) and zinc (Zn) mobility and availability in soil. Dried rye straw (Cecale cereale L.), clover aboveground parts (Trifolium pratense L.) or calcium carbonate were added to determine the effects on soil micronutrient mobility. To test the importance of soil–water saturation mediated by earthworms, soil samples were modified to 60% (control) and 100% (as in casts) water holding capacity (WHC). To assess availability of micronutrients, a cucumber plant (Cucumis sativus L.) bioassay were used. Earthworm casts had generally higher amounts of water-soluble micronutrients compared with bulk soils regardless of their moisture contents. The increased micronutrient mobility was more pronounced in casts from soil samples amended with plant residues (especially with straw) and was significantly higher than mobility in control soil for at least 1 week after the casts were deposited. Pre-incubation of soils amended with clover or straw with living earthworms for 4 weeks produced an increase in both shoot biomass and translocation rate of micronutrients (Mn, Zn) into xylem sap of cucumber compared to soils not worked by earthworms. The earthworm-mediated plant performances were determined 4 weeks after the earthworms were removed. The results demonstrated that earthworms can significantly impact the formation of mobile and available micronutrients in a soil. The relationship between micronutrient availability to cucumber plants and earthworm contribution to nitrogen (N) mineralization and micronutrient mobility are discussed. 相似文献
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Silaffins are involved in the formation of the cell walls of diatoms. It is known that silaffins can precipitate silica in vitro, forming nano- and micro-particles in the shape of spheres and plates containing many pores. It is important to note that the deposition of silica and the particle morphology in the presence of silaffins affects chemical and physical agents (e.g., peptides, polyamines, phosphate, nitrogen, and the mechanical changes of the reaction mixture). It is believed that silaffins act as an organic matrix for silica-genesis and that silica pore size should reflect the pattern of a matrix. Here, biotechnology related to silaffins is discussed in the context of “a hypothesis of silaffin matrix” and “the LCPA-phosphate model”. We discuss the most promising area of silaffin biotechnology—the development of production methods for silicon structures with desired shapes and nanostructural properties that can be used to create biocompatible materials. 相似文献
5.
Nikolai Bityutskii Helena Davydovskaya Kirill Yakkonen 《Journal of plant nutrition》2017,40(8):1152-1164
Aluminum (Al) negatively interferes with the uptake or transport of different nutrients. The aim of our work was to compare the Al tolerance and micronutrient accumulation: iron (Fe), zinc (Zn) and manganese (Mn), in cereal species (winter wheat, spring wheat, winter rye, oats and barley) contrasting in Fe efficiency. Our previous screening in a calcareous soil showed that oats and barley were more Fe-efficient than spring wheat, winter wheat or winter rye. In Al stress conditions, both oats and barley exhibited more effectiveness in Fe acquisition and translocation from root to shoot in comparison to winter wheat, spring wheat and winter rye. Also, oats and barley responded to Al toxicity by less Al-retarded shoot biomass than other cereal species. A combination of tolerance mechanisms appears to have great importance for Al tolerance including mechanisms underlying Fe efficiency in cereal seedlings. 相似文献
6.
Orlova Nataliya Abakumov Evgeny Orlova Elena Yakkonen Kirill Shahnazarova Vlada 《Journal of Soils and Sediments》2019,19(6):2708-2716
Purpose
Biochar is one of the most widely used ameliorants for soil amendment, which is known as factor which rises crop yields and levels of soil biological activity. Nowadays, it is under investigated how biochar application affects the dynamics of the humic components and whole soil organic matter (SOM) and the processes of its alteration. This investigation is aimed to evaluate the influence of biochar on the content, composition, and transformation of humic acids (HAs) as the main component of the SOM.
Materials and methodsThe incubation experiment was carried out on three Podzol Antric soils, with varying amounts of initial total organic carbon. The incubation time was 90 days, using biochar gravimetric doses of 0.1 and 1.0%. The biochar was produced by fast pyrolysis of birch and aspen wood at 550 °С. Humus composition was analyzed for the organic matter fractions extracted with 0.1 M NaOH (containing HAs 1 + fulvic acids (FAs) 1) and 0.1 M Na4P2O7 (containing HAs 1 + FAs 1 + HAs 2 + FAs 2). Isolated HAs were characterized for their elemental composition (C, N, H, and S) and molecular composition with the use of solid-state 13C nuclear magnetic resonance (13C-NMR) techniques.
Results and discussionWe found that 0.1% of biochar amendment does not influence SOM mineralization, but 1.0% of biochar increases the mineralization by 15–18%. This process is accompanied by changes in the composition and properties of the HS. The increased proportion of HA aromatic fragments in biochar indicates an increasing of their stability. However, in soils with high humus content and a significant amount of insoluble matter, the processes of mineralization and the growth of HAs are taking place simultaneously. The replenishment of HAs could be the outcome of both the intensification of the transformation processes (mineralization and humification) of the more sustainable insoluble matter compounds and the humification of the biochar itself.
ConclusionsThe influence of biochar on humification in Podzol Antric soils was revealed on the basis of incubation experiment. Both negative and positive changes under biochar in HS system were demonstrated. The active decrease of humus total contents and also the labile HS ought to qualify as negative changes. The increase of HA chemical maturity that leads to the stability of humus in whole as well as the intensive new HA formation thought to qualify as positive changes.
相似文献7.
Tsiroulnikov K Rezai H Bonch-Osmolovskaya E Nedkov P Gousterova A Cueff V Godfroy A Barbier G Métro F Chobert JM Clayette P Dormont D Grosclaude J Haertlé T 《Journal of agricultural and food chemistry》2004,52(20):6353-6360
Transmissible spongiform encephalopathies are caused by accumulation of highly resistant misfolded amyloid prion protein PrPres and can be initiated by penetration of such pathogen molecules from infected tissue to intact organism. Decontamination of animal meal containing amyloid prion protein is proposed thanks to the use of proteolytic enzymes secreted by thermophilic bacteria Thermoanaerobacter, Thermosipho, and Thermococcus subsp. and mesophilic soil bacteria Streptomyces subsp. Keratins alpha and beta, which resemble amyloid structures, were used as the substrates for the screening for microorganisms able to grow on keratins and producing efficient proteases specific for hydrolysis of beta-sheeted proteic structures, hence amyloids. Secretion of keratin-degrading proteases was evidenced by a zymogram method. Enzymes from thermophilic strains VC13, VC15, and S290 and Streptomyces subsp. S6 were strongly active against amyloid recombinant ovine prion protein and animal meal proteins. The studied proteases displayed broad primary specificities hydrolyzing low molecular mass peptide model substrates. Strong amyloidolytic activity of detected proteases was confirmed by experiments of hydrolysis of PrPres in SAFs produced from brain homogenates of mice infected with the 6PB1 BSE strain. The proteases from Thermoanaerobacter subsp. S290 and Streptomyces subsp. S6 are the best candidates for neutralization/elimination of amyloids in meat and bone meal and other protein-containing substances and materials. 相似文献
8.
Valentin Golosov Alexander Koiter Maxim Ivanov Kirill Maltsev Artyom Gusarov Aidar Sharifullin Irina Radchenko 《Journal of Soils and Sediments》2018,18(12):3388-3403
Purpose
Forest–steppe and the southern forest ecotones of European Russia (ER) are the most productive agricultural areas in Russia. Both climate and land use changes have occurred within the ER during last 30 years. These changes can lead to changes in the timing, magnitude, and spatial distribution of soil erosion rates on cultivated lands. The objective of this research was to assess the trends in soil erosion rates since the 1960s for two agricultural regions of ER.Materials and methods
Rates of soil erosion were estimated for two time windows (1963–1986 and 1986–2015) within the two agricultural regions. Both regions are characterized by a high proportion of cropland (>?60%), and within each region, one river basin and one 1st–3rd-order agricultural catchment were selected for a detailed assessment of soil erosion rates. Erosion models and visual interpretation of satellite images were used for the evaluation of the erosion rates for the river basins. Sediment budget assessments, 137Cs dating, geomorphologic mapping, and erosion models were used for the evaluation of the sediment redistribution for the two time windows in agricultural catchments.Results and discussion
At the river basin scale, the mean annual erosion rate did not change in the western part of forest–steppe ecotone; however, there was a weak negative trend in the mean annual erosion rate for the eastern part of the southern forest ecotone. A large negative trend in the erosion rate was found for both small agricultural catchments. In all cases, the reduction in the erosion rates was mainly associated with a decrease of surface runoff during snowmelt, as a result of an increase in both the air and soil temperatures during winter season. The soil loss reduction during snowmelt was counteracted by an equal increase in rainfall erosion due to increase of rainfall intensity in western part of forest–steppe ecotone.Conclusions
Reduction of surface runoff during spring snowmelt was the main reason the erosion rates declined on cultivated lands within the forest–steppe and southern forest ecotones of ER. Evaluation of ephemeral gully erosion rate was not incorporated into State Hydrological Institute erosion model used for the evaluation of the soil losses during snowmelt. This has led to an underestimation of the total soil losses for the 1963–1986 time window for all study sites.9.
Johannessen OM Khvorostovsky K Miles MW Bobylev LP 《Science (New York, N.Y.)》2005,310(5750):1013-1016
A continuous data set of Greenland Ice Sheet altimeter height from European Remote Sensing satellites (ERS-1 and ERS-2), 1992 to 2003, has been analyzed. An increase of 6.4 +/- 0.2 centimeters per year (cm/year) is found in the vast interior areas above 1500 meters, in contrast to previous reports of high-elevation balance. Below 1500 meters, the elevation-change rate is -2.0 +/- 0.9 cm/year, in qualitative agreement with reported thinning in the ice-sheet margins. Averaged over the study area, the increase is 5.4 +/- 0.2 cm/year, or approximately 60 cm over 11 years, or approximately 54 cm when corrected for isostatic uplift. Winter elevation changes are shown to be linked to the North Atlantic Oscillation. 相似文献
10.
Tarassov K Messier V Landry CR Radinovic S Serna Molina MM Shames I Malitskaya Y Vogel J Bussey H Michnick SW 《Science (New York, N.Y.)》2008,320(5882):1465-1470
Protein interactions regulate the systems-level behavior of cells; thus, deciphering the structure and dynamics of protein interaction networks in their cellular context is a central goal in biology. We have performed a genome-wide in vivo screen for protein-protein interactions in Saccharomyces cerevisiae by means of a protein-fragment complementation assay (PCA). We identified 2770 interactions among 1124 endogenously expressed proteins. Comparison with previous studies confirmed known interactions, but most were not known, revealing a previously unexplored subspace of the yeast protein interactome. The PCA detected structural and topological relationships between proteins, providing an 8-nanometer-resolution map of dynamically interacting complexes in vivo and extended networks that provide insights into fundamental cellular processes, including cell polarization and autophagy, pathways that are evolutionarily conserved and central to both development and human health. 相似文献