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^(15)N tracers and microbial analyses reveal in situ N_(2)O sources in contrasting water regimes of a drained peatland forest

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pedosphere 2024年第4期34卷 749-758页

作者： Mohit MASTA Mikk ESpENBERG Laura KUUSEMETS jaan p.rn Sandeep THAYAMKOTTU Holar SEpp Kalle KIRSIMÄE Fotis SGOURIDIS Kuno KASAK Kaido SOOSAAR Ülo MANDER Institute of Ecology and Earth Sciences University of TartuVanemuise Street 46Tartu 51003Estonia School of Geographical Sciences University of BristolUniversity RoadBristol BS81SSUK

Managed peatlands are a significant source of nitrous oxide(N_(2)O),a powerful greenhouse gas and stratospheric ozone *** to the complexity and diversity of microbial N_(2)O processes,different methods such as tracer,isotopomer,and microbiological technologies are required to understand these *** combined application of different methods helps to precisely estimate these processes,which is crucial for the future management of drained peatlands,and to mitigate soil degradation and negative atmospheric *** this study,we investigated N_(2)O sources by combining tracer,isotopomer,and microbial analysis in a drained peatland forest under flooded and drained *** average,the nitrification genes showed higher abundances in the drained treatment,and the denitrification genes showed higher abundances in the flooded *** is consistent with the underlying chemistry,as nitrification requires oxygen while denitrification is *** observed significant differences in labelled N_(2)O fluxes between the drained and flooded *** emissions of N_(2)O from the flooded treatment were nearly negligible,whereas the N_(2)O evolved from the nitrogen-15(^(15)N)-labelled ammonium(^(15)NH4+)in the drained treatment peaked at 147μg ^(15)N m^(-2) h^(-1).This initially suggested nitrification as the driving mechanism behind N_(2)O fluxes in drained peatlands,but based on the genetic data,isotopic analysis,and N_(2)O mass enrichment,we conclude that hybrid N_(2)O formation involving ammonia oxidation was the main source of N_(2)O emissions in the drained *** on the ^(15)N-labelled nitrate(^(15)NO3-)tracer addition and gene copy numbers,the low N_(2)O emissions in the flooded treatment came possibly from complete denitrification producing inert *** atomic level,we observed selective enrichment of mass 45 of N_(2)O molecule under ^(15)NH4+amendment in the drained treatment and enrichment of both masses 45 and 46 under

关键词： denitrification nitrification N_(2)O quantitative polymerase chain reaction

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Impact of ethnicity on the outcomes of acute pancreatitis:insights from US National Inpatient Sample

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Journal of pancreatology 2024年第1期7卷 86-89页

作者： Ali jaan Sheza Malik Joel E.McFarland Erik T.Olson Byron Cryer Department of Internal Medicine Rochester General HospitalRochesterNY Department of Gastroenterology Rochester General HospitalRochesterNY Department of Gastroenterology Baylor University Medical CenterDallasTX

Introduction Acute pancreatitis(Ap),characterized by inflammation of the pancreas,is a critical medical condition with potentially life-threatening consequences.[1]Despite significant advancements in medical science,the prognosis of Ap remains challenging and is influenced by a multitude of *** these factors,ethnicity has emerged as a compelling variable that may play a pivotal role in determining the outcomes and severity of Ap.[2]Understanding the influence of ethnicity on Ap outcomes has immense significance for several ***,it provides a unique opportunity to gain critical insights into the pathophysiology of the disease.

关键词： pancreatitis insight consequences

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Method of cells-based multiscale modeling of elastic properties of filament wound C/C-SiC including free Si and matrix porosity

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Journal of Materials Science & Technology 2019年第12期35卷 2906-2918页

作者： Evan J.pineda Marek Fassin Stefanie Reese jaan-Willem Simon NASA Glenn Research Center 21000 Brookpark RoadMS 49/7ClevelandOH 44135United States Institute for Applied Mechanics RWTH Aachen UniversityMies-van-der-Rohe-Str.152074 AachenGermany

Three different multiscale models, based on the method of cells(generalized and high fidelity) micromechanics models were developed and used to predict the elastic properties of C/C-SiC composites. In particular, the following multiscale modeling strategies were employed: Concurrent modeling of all phases using the generalized method of cells, synergistic(two-way coupling in space) multiscale modeling with the generalized method of cells, and hierarchical(one-way coupling in space) multiscale modeling with the high fidelity generalized method of cells. The three models are validated against data from a hierarchical multiscale finite element model in the literature for a repeating unit cell of C/***, the multiscale models are used in conjunction with classical lamination theory to predict the stiffness of C/C-SiC plates manufactured via a wet filament winding and liquid silicon infiltration process recently developed by the German Aerospace Institute. Finally, un-reacted Si(or free Si) and porosity in the C matrix are included in the multiscale model, and the effect of these new phases on the stiffness and local stresses are considered.

关键词： Multiscale modeling C/C-SiC Ceramic matrix composites

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population-level performance of Arabidopsis thaliana (L.) Heynh in dense monocultures

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Journal of plant Ecology 2020年第2期13卷 241-246页

作者： Susanna Vain Iris Gielen jaan Liira Kristjan Zobel Department of Botany University of Tartu40 Lai St.51005 TartuEstonia Hugo Treffner Gymnasium 12 Munga St.51007 TartuEstonia

Aims Very little is known about the performance of non-agricultural plant species in monocultures,even though nearly all agricultural species have experienced the transition from multi-species environments to dense monospecific stands during the breeding *** the light of recent work that highlighted the possibility that the weedy species Arabidopsis thaliana can offer novel insight into crop breeding,we aimed to test the effect of sowing density on group and individual performance in different photoperiod environments in *** We studied the performance of *** Cvi-0 *** choice of Cvi-0 was based on a preliminary experiment in which plants of Cvi-0 ecotype exhibited high competitive *** densities used were 17.6,8.8,4.4,2.2 and 1.1 cm^(2) per plant and photoperiod environments 12 or 16 h of day *** Findings In this experiment,populations attained constant total seed yield for all *** interaction effect occurred,as at high sowing density and at longer day length plants produced heavier seeds,whereas at shorter day length seed weight was negatively related to plant *** results shed light on different strategies that annual plants can adopt when they face intense intraspecific competition,and could help to offer new perspectives for breeding crops with enhanced group performance.

关键词： Arabidopsis thaliana constant final yield intraspecific competition monoculture photoperiod

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Shallow sediment transport flow computation using time-varying sediment adaptation length

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International Journal of Sediment Research 2014年第2期29卷 171-183页

作者： jaan Hui pU Khalid HUSSAIN Song-dong SHAO Yue-fei HUANG School of Engineering and Informatics University of Bradford West Yorkshire BD7 1DPUK.Lecturer School of Engineering University of Bradford West Yorkshire BD7 1 DPUK.Head Department of Civil and Structure Engineering University of Sheffield Sheffield S1 3JDUK Senior Lecturer State Key Laboratory of Hydro-Science and Engineering Tsinghua University

Based on the common approach,the adaptation length in sediment transport is normally estimated astemporally ***,this approach might not be theoretically justified as the process of reaching the sediment transport equilibrium stage is affected by the flow conditions in time,especially for fast moving flows,such as scour-hole developing *** this study,the two-dimensional(2D) shallow water formulation together with a sediment continuity-concentration(SCC) model were applied to flow with mobile sediment boundary.A timevarying approach was proposed to determine the sediment transport adaptation length to simulate the sediment erosion-deposition *** proposed computational model was based on the Finite Volume(FV) *** Monotone Upwind Scheme of Conservative Laws(MUSCL)-Hancock scheme was used with the Harten Lax van Leer-contact(HLLC) approximate Riemann solver to discretize the FV *** the flow applications of this paper,a highly discontinuous dam-break,fast sediment transport flow was used to calibrate the proposed timevarying sediment adaptation length *** the calibrated model was further applied to two separate experimental sediment transport flow applications documented in the literature,i.e.a highly concentrated sediment transport flow in a wide alluvial channel and a sediment aggradation *** agreement with the experimental data were obtained with the proposed model *** tests prove that the proposed model,which was calibrated by the discontinuous dam-break bed scouring flow,also performed well to represent rapid bed change and steady sediment mobility conditions.

关键词： Finite volume model Harten Lax van Leer-contact solver Monotonic upwind scheme Sediment transport Shallow water model Time-varying sediment adaptation length

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Flow turbulence presented by different vegetation spacing sizes within a submerged vegetation patch

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Journal of Hydrodynamics 2023年第6期35卷 1131-1145页

作者： Chukwuemeka Kingsley John jaan H.pu Yakun Guo prashanth R.Hanmaiahgari Manish pandey Faculty of Engineering and Informatics University of BradfordBradfordUK Department of Civil Engineering Indian Institute of TechnologyKharagpurIndia National Institute of Technology(NIT) WarangalIndia

This study presents results from a vegetation-induced flow experimental study which investigates 3-D turbulence structure profiles,including Reynolds stress,turbulence intensity and bursting analysis of open channel *** vegetation densities have been built between the adjacent vegetations,and the flow measurements are taken using acoustic Doppler velocimeter(ADV)at the locations within and downstream of the vegetation *** different tests are conducted,where the first test has compact vegetations,while the second and the third tests have open spaces created by one and two empty vegetation slots within the vegetated *** reveals that over 10%of eddies size is generated within the vegetated zone of compact vegetations as compared with the fewer *** turbulence structures variation is also observed at the points in the non-vegetated *** findings from burst-cycle analysis show that the sweep and outward interaction events are dominant,where they further increase away from the *** effect of vegetation on the turbulent burst cycle is mostly obvious up to approximately two-third of vegetation height where this phenomenon is also observed for most other turbulent structure.

关键词： Velocity profiles acoustic Doppler velocimeter(ADV) turbulent intensities Reynolds stress turbulent bursting vegetated flow vegetation spacing sizes

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TanDEM-X multiparametric data features in sea ice classification over the Baltic sea

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Geo-Spatial Information Science 2021年第2期24卷 313-332,I0009页

作者： Marjan Marbouti Oleg Antropov jaan praks patrick B.Eriksson Vahid Arabzadeh Eero Rinne Matti Leppärant Institute for Atmospheric and Earth System Research/physics Faculty of ScienceUniversity of HelsinkiHelsinkiFinland VTT Technical Research Centre of Finland EspooFinland Aalto University Department of Electronics and NanoengineeringEspooFinland Finnish Meteorological Institute HelsinkiFinland Aalto University Department of Applied PhysicsNew Energy Technologies GroupEspooFinland

In this study,we assess the potential of X-band Interferometric Synthetic Aperture Radar imagery for automated classification of sea ice over the Baltic Sea.A bistatic SAR scene acquired by the TanDEM-X mission over the Bothnian Bay in March of 2012 was used in the *** intensity,interferometric coherence magnitude,and interferometric phase have been used as informative features in several classification *** combinations of classification features were evaluated using Maximum likelihood(ML),Random Forests(RF)and Support Vector Machine(SVM)classifiers to achieve the best possible discrimination between open water and several sea ice types(undeformed ice,ridged ice,moderately deformed ice,brash ice,thick level ice,and new ice).Adding interferometric phase and coherence-magnitude to backscatter-intensity resulted in improved overall classification per-formance compared to using only *** RF algorithm appeared to be slightly superior to SVM and ML due to higher overall accuracies,however,at the expense of somewhat longer processing *** best overall accuracy(OA)for three methodologies were achieved using combination of all tested features were 71.56,72.93,and 72.91%for ML,RF and SVM classifiers,*** to OAs of 62.28,66.51,and 63.05%using only backscatter intensity,this indicates strong benefit of SAR interferometry in discriminating different types of sea *** contrast to several earlier studies,we were particularly able to successfully discriminate open water and new ice classes.

关键词： Sea ice classification Random Forests(RF) Maximum Likelihood(ML) Support Vector Machine(SVM) backscatter coherence sar interferometry Synthetic Aperture Radar(SAR)

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paleo-glacial reconstruction of the Thajwas glacier in the Kashmir Himalaya using 10Be cosmogenic radionuclide dating

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Geoscience Frontiers 2022年第6期13卷 30-40页

作者： Omar jaan paul Shakil Ahmad Romshoo Reyaz Ahmad Dar pankaj Kumar Soumya prakash Dhal Sundeep Chopra Department of Earth Sciences University of KashmirSrinagarIndia Islamic University of Science and Technology(IUST) KashmirIndia Inter-University Accelerator Centre(IUAC) New DelhiIndia Department of Geoinformatics University of KashmirSrinagarIndia

Quantitative glacial chronologies of past glaciations are sparse in the Himalaya, and mostly absent in the Kashmir Himalaya. We used cosmogenicBe exposure dating, and geomorphological mapping to reconstruct glacial advances of the Thajwas Glacier(TG) in the Great Himalayan Range of the Kashmir Himalaya. FromBe exposure dating of ten moraine boulders, four glacial stages with ages ~20.77 ±2.28 ka, ~11.46 ± 1.69 ka, ~9.12 ± 1.39 ka and ~4.19 ± 0.78 ka, were identified. The reconstructed cosmogenic radionuclide ages confirmed the global Last Glacial Maximum(g LGM), Younger Dryas, Early Holocene, and Neoglaciation episodes. As per area and volume change analyses, the TG has lost 51.1 km~2 of its area and a volume of 2.64 km~3 during the last 20.77 ± 2.28 ka. Overall, the results suggested that the TG has lost 64% of area and 73% of volume from the Last glacial maximum to Neoglaciation and about 85.74% and 87.67% of area and volume, respectively, from Neoglaciation to the present day. The equilibrium line altitude of the TG fluctuated from 4238 m a.s.l present to3365 m a.s.l during the g LGM(20.77 ± 2.28 ka). The significant cooling induced by a drop in mean ambient temperature resulted in a positive mass balance of the TG during the g LGM. Subsequently the melting accelerated due to the continuing rise of the global ambient temperature. paleo-glacial history reconstruction of the Kashmir Himalaya, with its specific geomorphic and climatic setting, would help close the information gap about the chronology of past regional glacial episodes.

关键词： Glacier reconstruction Cosmogenic 10Be gLGM Kashmir Himalaya Equilibrium Line Altitude

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Submerged flexible vegetation impact on open channel flow velocity distribution: An analytical modelling study on drag and friction

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Water Science and Engineering 2019年第2期12卷 121-128页

作者： jaan H. pu Awesar Hussain Ya-kun Guo Nikolaos Vardakastanis prashanth R. Hanmaiahgari Dennis Lam Faculty of Engineering and Informatics University of BradfordBradford BD7 1DPUK Department of Civil Engineering Indian Institute of TechnologyKharagpur 721302India

In this paper,an analytical model that represents the streamwise velocity distribution for open channel flow with submerged flexible vegetation is *** the present vegetated flow modelling,the whole flow field has been separated into two layers vertically: a vegetated layer and a non-vegetated free-water *** the vegetated layer,an analysis of the mechanisms affecting water flow through flexible vegetation has been *** the non-vegetated layer,a modified log-law equation that represents the velocity profile varying with vegetation height has been *** on the studied analytical model,a sensitivity analysis has been conducted to assess the influences of the drag (CD) and friction (Cf ) coefficients on the flow *** investigated ranges of CD and Cf have also been compared to published *** findings suggest that the CD and Cf values are non-constant at different depths and vegetation densities,unlike the constant values commonly suggested in *** phenomenon is particularly clear for flows with flexible vegetation,which is characterised by large deflection.

关键词： Analytical model Flexible vegetation Flow velocity Friction Drag Submerged vegetation

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Development of a novel electrospun nanofibrous delivery system for poorly water-soluble β-sitosterol

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Asian Journal of pharmaceutical Sciences 2016年第4期11卷 500-506页

作者： Urve paaver Ivo Laidmae Hélder A.Santos Jouko Yliruusi jaan Aruvali Karin Kogermann Jyrki Heinamaki Faculty of Medicine Department of PharmacyUniversity of TartuNooruse150411 TartuEstonia Faculty of pharmacy Division of Pharmaceutical Chemistry and TechnologyUniversity of HelsinkiViikinkaari 5EFI-00014HelsinkiFinland Institute of Ecology and Earth Sciences University of TartuRavila 14a50411 TartuEstonia

Electrospinning was used as a novel technique for fabricating polymeric nanofibers of a serum cholesterol lowering and poorly water-soluble plant sterol, β-sitosterol. Chitosan was used as a stabilizer/carrier polymer. The mean diameters of nanofibers ranged from 150 nm to218 nm. β-sitosterol was in an amorphous form and homogeneously dispersed in the nanofibers. The β-sitosterol-loaded nanofibers were freely water-soluble and exhibited very short lag-time in releasing the plant sterol. The dissolution was associated with an immediate recrystallization of β-sitosterol in submicron level. In conclusion, electrospinning is a promising future technology for the formulation of poorly water-soluble plant sterols.

关键词： Electrospinning plant sterol β-sitosterol Nanofibers Solid-state properties Dissolution

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