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  • 1
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    High-resolution scanning x-ray diffraction microscopy (2008)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2008-07-19
    Description: Coherent diffractive imaging (CDI) and scanning transmission x-ray microscopy (STXM) are two popular microscopy techniques that have evolved quite independently. CDI promises to reach resolutions below 10 nanometers, but the reconstruction procedures put stringent requirements on data quality and sample preparation. In contrast, STXM features straightforward data analysis, but its resolution is limited by the spot size on the specimen. We demonstrate a ptychographic imaging method that bridges the gap between CDI and STXM by measuring complete diffraction patterns at each point of a STXM scan. The high penetration power of x-rays in combination with the high spatial resolution will allow investigation of a wide range of complex mesoscopic life and material science specimens, such as embedded semiconductor devices or cellular networks.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Thibault, Pierre -- Dierolf, Martin -- Menzel, Andreas -- Bunk, Oliver -- David, Christian -- Pfeiffer, Franz -- New York, N.Y. -- Science. 2008 Jul 18;321(5887):379-82. doi: 10.1126/science.1158573.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Paul Scherrer Institut, 5232 Villigen PSI, Switzerland. pierre.thibault@psi.ch〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18635796" target="_blank"〉PubMed〈/a〉
    Keywords: Algorithms ; Fourier Analysis ; Image Processing, Computer-Assisted ; Microscopy/instrumentation/*methods ; Nanostructures/*ultrastructure ; Scattering, Small Angle ; *X-Ray Diffraction
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 2
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    Microbial community responses determine how soil–atmosphere exchange of carbonyl sulfide, carbon monoxide, and nitric oxide responds to soil moisture (2019)
    Copernicus
    Details
    Publication Date: 2019-03-25
    Description: Carbonyl sulfide (OCS) plays an important role in the global sulfur cycle and is relevant for climate change due to its role as a greenhouse gas, in aerosol formation and atmospheric chemistry. The similarities of the carbon dioxide (CO2) and OCS molecules within chemical and plant metabolic pathways have led to the use of OCS as a proxy for global gross CO2 fixation by plants (gross primary production, GPP). However, unknowns such as the OCS exchange from soils, where simultaneous OCS production (POCS) and consumption (UOCS) occur, currently limits the use of OCS as a GPP proxy. We estimated POCS and UOCS by measuring net fluxes of OCS, carbon monoxide (CO), and nitric oxide (NO) in a dynamic chamber system fumigated with air containing different mixing ratios [OCS]. Nine soils with different land use were rewetted and soil–air exchange was monitored as soils dried out to assess responses to changing moisture. A major control of OCS exchange was the total amount of available sulfur in the soil. POCS production rates were highest for soils at WFPS (water-filled pore space) 〉60 % and rates were negatively related to thiosulfate concentrations. These moist soils switched from a net source to a net sink activity at moderate moisture levels (WFPS 15 % to 37 %). For three soils we measured NO and CO mixing ratios at different mixing ratios of OCS and revealed that NO and potentially CO exchange rates are linked to UOCS at moderate soil moisture. High nitrate concentrations correlated with maximum OCS release rates at high soil moisture. For one of the investigated soils, the moisture and OCS mixing ratio was correlated with different microbial activity (bacterial 16S rRNA, fungal ITS RNA relative abundance) and gene transcripts of red-like cbbL and amoA.
    Print ISSN: 2199-3971
    Electronic ISSN: 2199-398X
    Topics: Geosciences
    Published by Copernicus on behalf of European Geosciences Union.
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  • 3
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    Reviews and Syntheses: Carbonyl Sulfide as a Multi-scale Tracer for Carbon and Water Cycles (2017)
    Copernicus
    Details
    Publication Date: 2017-10-24
    Description: For the past decade, observations of carbonyl sulfide (OCS or COS) have been investigated as a proxy for carbon uptake by plants. OCS is destroyed by enzymes that interact with CO2 during photosynthesis, namely carbonic anhydrase (CA) and RuBisCO, where CA is the more important. The majority of sources of OCS to the atmosphere are geographically separated from this large plant sink, whereas the sources and sinks of CO2 are co-located in ecosystems. The drawdown of OCS can therefore be related to the uptake of CO2 without the added complication of co-located emissions comparable in magnitude. Here we review the state of our understanding of the global OCS cycle and its applications to ecosystem carbon cycle science. OCS uptake is correlated well to plant carbon uptake, especially at the regional scale. OCS can be used in conjunction with other independent measures of ecosystem function, like solar-induced fluorescence and carbon and water isotope studies. More work needs to be done to generate global coverage for OCS observations and to link this powerful atmospheric tracer to systems where fundamental questions concerning the carbon and water cycle remain.
    Print ISSN: 1810-6277
    Electronic ISSN: 1810-6285
    Topics: Biology , Geosciences
    Published by Copernicus on behalf of European Geosciences Union.
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  • 4
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    Reviews and syntheses: Carbonyl sulfide as a multi-scale tracer for carbon and water cycles (2018)
    Copernicus
    Details
    Publication Date: 2018-06-18
    Description: For the past decade, observations of carbonyl sulfide (OCS or COS) have been investigated as a proxy for carbon uptake by plants. OCS is destroyed by enzymes that interact with CO2 during photosynthesis, namely carbonic anhydrase (CA) and RuBisCO, where CA is the more important one. The majority of sources of OCS to the atmosphere are geographically separated from this large plant sink, whereas the sources and sinks of CO2 are co-located in ecosystems. The drawdown of OCS can therefore be related to the uptake of CO2 without the added complication of co-located emissions comparable in magnitude. Here we review the state of our understanding of the global OCS cycle and its applications to ecosystem carbon cycle science. OCS uptake is correlated well to plant carbon uptake, especially at the regional scale. OCS can be used in conjunction with other independent measures of ecosystem function, like solar-induced fluorescence and carbon and water isotope studies. More work needs to be done to generate global coverage for OCS observations and to link this powerful atmospheric tracer to systems where fundamental questions concerning the carbon and water cycle remain.
    Print ISSN: 1726-4170
    Electronic ISSN: 1726-4189
    Topics: Biology , Geosciences
    Published by Copernicus on behalf of European Geosciences Union.
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  • 5
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    Microbial community responses determine how soil-atmosphere exchange of carbonyl sulfide, carbon monoxide and nitric oxide respond to soil moisture (2018)
    Copernicus
    Details
    Publication Date: 2018-05-16
    Description: Carbonyl sulfide (OCS) plays an important role in the global sulfur cycle and is relevant for climate change due to its role as a greenhouse gas, in aerosol formation and atmospheric chemistry. The similarities of the carbon dioxide (CO2) and OCS molecules within chemical and plant metabolic pathways have led to the use of OCS as a proxy for global gross CO2 fixation by plants (GPP). However, unknowns such as the OCS exchange from soils, where simultaneous OCS production (POCS) and consumption (UOCS) occur, currently limits the use of OCS as a GPP proxy. We estimated POCS and UOCS by measuring net fluxes of OCS, carbon monoxide (CO) and nitric oxide (NO) in a dynamic chamber system fumigated with air containing different [OCS]. Several different soils were rewetted and soil-air exchange monitored as soils dried out to investigate responses to changing moisture levels. A major control of OCS exchange is the total amount of available S in the soil. POCS production rates were highest for soils at WFPS〉60% and rates were negatively related to thiosulfate concentrations. These soils flipped from being net sources to net sinks of OCS at moderate moisture levels (WFPS 15 to 37%). By measuring CO and NO while fumigating soils at different levels of OCS, we could show that CO consumption and NO exchange are linked to UOCS under moderate soil moisture. Based on the OCS:CO flux ratio two different UOCS processes could be separated. For one of the investigated soils, we demonstrated changes in microbial activity and red-like cbbL and amoA genes that suggested shifts in the UOCS processes with moisture and OCS concentration. This supports the view that Ribulose-1,5-Bisphosphate-Carboxylase (RubisCO) plays an important role for UOCS and demonstrates a link to the nitrogen cycle.
    Electronic ISSN: 2199-3998
    Topics: Geosciences
    Published by Copernicus on behalf of European Geosciences Union.
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  • 6
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    Carbonyl sulfide (OCS) exchange between soils and the atmosphere affected by soil moisture and compensation points (2018)
    Copernicus
    Details
    Publication Date: 2018-01-30
    Description: Carbonyl sulfide (OCS) is a chemically quite stable gas in the troposphere (lifetime ~2–6 years) and consequently some of it is transported up to the stratosphere where it contributes to the stratospheric sulfate layer. Due to the similarities in uptake mechanism between OCS and CO2, the use of OCS as a proxy for CO2 in ecosystem gross primary production (GPP) has been proposed. For this application a good understanding of uptake (UOCS) and production (POCS) processes of OCS in an ecosystem is required. A new OCS quantum cascade laser coupled with an automated soil chamber system enabled us to measure the soil-atmosphere OCS exchange of four different soil samples with high precision. The adjustment of the chamber air to different OCS mixing ratios (50, 500, and 1000ppt) allowed us to separate production and consumption processes and to estimate compensation points (CPs) for the OCS exchange. At an atmospheric mixing ratio of 1000ppt, the maximum UOCS was of the order of 22 to 110pmolg−1h−1 for needle forest soil samples and of the order of 3 to 5pmolg−1h−1 for an agricultural mineral soil, both measured at moderate soil moisture. Uptake processes (UOCS) were dominant at all soil moistures for the forest soils, while POCS exceeded UOCS at higher soil moistures for the agricultural soil, resulting in net emission. Hence, our results indicate that in (spruce) forests UOCS might be the dominant process, while in agricultural soils POCS at higher soil moisture and UOCS under moderate soil moisture seem to dominate the OCS exchange. The OCS compensation points (CPs) were highly dependent on soil water content and extended over a wide range of 130ppt to 1600ppt for the forest soils and 450ppt to 5500ppt for the agricultural soil. The strong dependency between soil water content and the compensation point value must be taken into account for all further analyses. The lowest CPs were found at about 20% water filled pore space (WFPSlab), implying the maximum of UOCS under these soil moisture conditions and excluding OCS emission under such conditions. We discuss our results in view of other studies about compensation points and the potential contribution of microbial groups.
    Print ISSN: 1810-6277
    Electronic ISSN: 1810-6285
    Topics: Biology , Geosciences
    Published by Copernicus on behalf of European Geosciences Union.
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