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Assessing the utility of dissolved organic matter photoreactivity as a predictor of in situ methylmercury concentration

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journal of Environmental Sciences 2018年第6期30卷 160-168页

作者： sara j.klapstein Susan E.Ziegler David A.Risk Nelson j.O'Driscoll Environmental Science Program Memorial University of Newfoundland Department of Earth Sciences St. Francis Xavier University Department of Earth and Environmental Science Acadia University

Methylmercury（MeHg） bioaccumulation is a growing concern in ecosystems worldwide. The absorption of solar radiation by dissolved organic matter（DOM） and other photoreactive ligands can convert MeHg into less toxic forms of mercury through photodemethylation. In this study, spectral changes and photoreactivity of DOM were measured to assess the potential to control photoreactions and predict in situ MeHg concentration. Water samples collected from a series of lakes in southwestern Nova Scotia in june, August, and September were exposed to controlled ultraviolet-A（UV-A） radiation for up to 24 hr. Dissolved organic matter photoreactivity, measured as the loss of absorbance at 350 nm at constant UV-A irradiation, was positively dependent on the initial DOM concentration in lake waters（r^2=0.94）. This relationship was consistent over time with both DOM concentration and photoreactivity increasing from summer into fall across lakes. Lake in situ MeHg concentration was positively correlated with DOM concentration and likely catchment transport in june（r = 0.77） but not the other sampling months. Despite a consistent seasonal variation in both DOM and Fe, and their respective correlations with MeHg, no discernable seasonal trend in MeHg was observed. However, a 3-year dataset from the 6 study lakes revealed a positive correlation between DOM concentration and both Fe（r = 0.91） and MeHg concentrations（r = 0.51） suggesting a more dominant landscape mobility control on *** DOM-MeHg relationships observed in these lakes highlights the need to examine DOM photoreactivity controls on MeHg transport and availability in natural waters particularly given future climate perturbations.

关键词： Methylmercury Dissolved organic carbon Photoreactions Kejimkujik National Park Freshwater lakes

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Mercury photoreduction and photooxidation in lakes：Effects of filtration and dissolved organic carbon concentration

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journal of Environmental Sciences 2018年第6期30卷 151-159页

作者： Nelson j.O’Driscoll Emma Vost Erin Mann sara klapstein Robert Tordon Matthew Lukeman Department of Earth & Environmental Science Acadia University Wolfville B4P 2R6 Nova Scotia Canada Environment Canada Dartmouth Nova Scotia Canada Department of Chemistry Acadia University Wolfville B4P 2R6 Nova Scotia Canada

Mercury is a globally distributed, environmental contaminant. Quantifying the retention and loss of mercury is integral for predicting mercury-sensitive ecosystems. There is little information on how dissolved organic carbon（DOC） concentrations and particulates affect mercury photoreaction kinetics in freshwater lakes. To address this knowledge gap,samples were collected from ten lakes in Kejimkujik National Park, Nova Scotia（DOC： 2.6–15.4 mg/L）. Filtered（0.2 μm） and unfiltered samples were analysed for gross photoreduction, gross photooxidation, and net reduction rates of mercury using pseudo first-order curves. Unfiltered samples had higher concentrations（p = 0.04） of photoreducible divalent mercury（Hg（II）RED）（mean of 754 ± 253 pg/L） than filtered samples（mean of 482 ± 206 pg/L）;however, gross photoreduction and photooxidation rate constants were not significantly different in filtered or unfiltered samples in early summer. DOC was not significantly related to gross photoreduction rate constants in filtered（R2= 0.43; p = 0.08） and unfiltered（R2= 0.02; p = 0.71） samples; DOC was also not significantly related to gross photooxidation rate constants in filtered or unfiltered samples. However, DOC was significantly negatively related with Hg（Ⅱ）RED in unfiltered（R2= 0.53; p = 0.04）, but not in filtered samples（R2= 0.04;p = 0.60）. These trends indicate that DOC is a factor in determining dissolved mercury photoreduction rates and particles partially control available Hg（Ⅱ）RED in lake water. This research also demonstrates that within these lakes gross photoreduction and photooxidation processes are close to being in balance. Changes to catchment inputs of particulate matter and DOC may alter mercury retention in these lakes and could partially explain observed increases of mercury accumulation in biota.

关键词： Mercury Photoreduction Photooxidation Dissolved organic carbon(DOC) Particulates Kejimkujik National Park

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Corrigendum to Mercury photoreduction and photooxidation in lakes:effects of filtration and dissolved organic carbon *** of Environmental Sciences 68(2018)151-159

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journal of Environmental Sciences 2021年第5期33卷 347-350页

作者： Nelson j.O'Driscol Emma Vost Erin Mann sara klapstein Robert Tordon Matthew Lukeman Department o f Earth&Environmental Science.Acadia University WolfuilleNova ScotiaCanada B4P 2R62 Environment Canada DartmouthNova Scotia Department of Chemistry Acadia UniversityWolfuilleNova ScotiaCanada B4P 2R6

"Filtered(0.2μm)and unfiltered samples were analyzed for gross photoreduction,gross photooxidation,and net reduction rates of mercury using pseudo first-order curves.

关键词： lakes Mercury dissolved

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Advanced imaging in surveillance of Barrett’s esophagus: Is the juice worth the squeeze?

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World journal of Gastroenterology 2019年第25期25卷 3108-3115页

作者： sara A Cerrone Arvind j Trindade Division of Gastroenterology Long Island Jewish Medical CenterZucker School of Medicine at Hofstra/NorthwellNorthwell Health System

Esophageal cancer is on the *** known precursor lesion is Barrett’s esophagus(BE).Patients with dysplasia are at higher risk of developing esophageal *** the gold standard for surveillance endoscopy involves taking targeted biopsies of abnormal areas as well as random biopsies every 1-2 cm of the length of the Barrett’*** studies have shown that this surveillance can miss dysplasia and *** imaging technologies have been developed that may help detect dysplasia in *** opinion review discusses advanced imaging in BE surveillance endoscopy and its utility in clinical practice.

关键词： Barrett’s esophagus Advanced imaging Chromoendoscopy Endomicroscopy

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Automatic characterization of spherical metal powders by microscope image analysis:a parallel computing approach

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journal of Iron and Steel Research International 2023年第11期30卷 2293-2300页

作者： Xiang Li Linyi Cui sara Shonkwiler sara McMains University of California BerkeleyBerkeleyCA94720USA The Hong Kong Polytechnic University Hong KongChina

The microstructural characteristics of spherical metal powders play an important role in determining the quality of mechanical parts manufactured by powder metallurgy *** the individual powder particles from their microscopic images is one of the most convenient and cost-efficient methods for the analysis of powder *** numerous image processing algorithms have been developed for automating the powder particle identification process,they perform less accurately in identifying adjacent particles that are heavily overlapped in their image *** propose an automatic algorithm to robustly and accurately identify spherical powder particles,especially heavily overlapped particles,from their microscope images.A parallel computing framework is designed to further enhance the computational efficiency of the proposed *** characteristics such as particle size distribution and the location of potential satellite particles have been derived from our identification *** accuracy and efficiency of our algorithm are validated by real-world scanning electron microscope images,outperforming other existing methods and achieving both precision and recall above 99%.

关键词： computing image overlapped

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The importance of large-diameter trees to the creation of snag and deadwood biomass

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Ecological Processes 2021年第1期10卷 380-393页

作者： james A.Lutz Soren Struckman sara j.Germain Tucker j.Furniss Department of Wildland Resources S.J.and Jessie E.Quinney College of Natural ResourcesUtah State University5230 Old Main HillLoganUT 84322-5230USA

Background:Baseline levels of tree mortality can,over time,contribute to high snag densities and high levels of deadwood(down woody debris)if fire is infrequent and decomposition is *** can be important for tree recruitment,and it plays a major role in terrestrial carbon cycling,but deadwood is rarely examined in a spatially explicit ***:Between 2011 and 2019,we annually tracked all trees and snags≥1 cm in diameter and mapped all pieces of deadwood≥10 cm diameter and≥1 m in length in 25.6 ha of Tsuga heterophylla/Pseudotsuga menziesii *** analyzed the amount,biomass,and spatial distribution of deadwood,and we assessed how various causes of mortality that contributed uniquely to deadwood ***:Compared to aboveground woody live biomass of 481 Mg ha^(−1)(from trees≥10 cm diameter),snag biomass was 74 Mg ha^(−1) and deadwood biomass was 109 Mg ha^(−1)(from boles≥10 cm diameter).Biomass from large-diameter trees(≥60 cm)accounted for 85%,88%,and 58%,of trees,snags,and deadwood,*** aboveground woody live and dead biomass was 668 Mg ha^(−1).The annual production of downed wood(≥10 cm diameter)from tree boles averaged 4 Mg ha^(−1) yr^(−1).Woody debris was spatially heterogeneous,varying more than two orders of magnitude from 4 to 587 Mg ha^(−1) at the scale of 20 m×20 m *** all causes of deadwood creation varied in importance between large-diameter trees and small-diameter *** of standing stems and deadwood had weak inverse distributions,reflecting the long period of time required for trees to reach large diameters following antecedent tree mortalities and the centennial scale time required for deadwood ***:Old-growth forests contain large stores of biomass in living trees,as well as in snag and deadwood biomass pools that are stable long after tree *** biomass(or carbon)in deadwood pools can lead to substantial underestimations of sequestration and stability.

关键词： Carbon sequestration Old-growth forest Pseudotsuga menziesii Tree mortality Tsuga heterophylla Wind River Forest Dynamics Plot

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Enzymatic and chemo-enzymatic strategies to produce highly valuable chiral amines from biomass with ω-transaminases on 2D zeolites

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National Science Review 2022年第9期9卷 10-18页

作者： j.Miguel Carceller Karen S.Arias Maria j.Climent sara Iborra Avelino Corma Instituto de Tecnologia Química (UPV-CSIC) Universitat Politècnica de València

Amino transaminases(ATAs) have been supported on a 2D ITQ-2 zeolite through electrostatic interactions, resulting in a highly stable active biocatalyst to obtain a variety of valuable chiral amines starting from prochiral ketones derived from biomass. We have extended the biocatalyst applications by designing a chemo-enzymatic process that allows, as the first step, prochiral ketones to be obtained from biomass-derived compounds through an aldol condensation–reduction step using a bifunctional metal/base catalyst. The prochiral ketone is subsequently converted into the chiral amine using the immobilized ATA. We show that it is feasible to couple both steps in a semi-continuous process to produce industrially relevant chiral amines with yields of >95% and ～100% enantiomer excess.

关键词： amino transaminase ITQ-2 zeolite chemo-enzymatic process biomass semi-continuous process Pd/MgO

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Decreased bioavailability of aminomethylphosphonic acid(AMPA)in genetically modified corn with activated carbon or calcium montmorillonite clay inclusion in soil

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journal of Environmental Sciences 2021年第2期33卷 131-143页

作者： sara E.Hearon Meichen Wang Thomas j.McDonald Timothy D.Phillips Veterinary Integrative Biosciences Department College of Veterinary Medicine and Biomedical Sciences Texas A&M Uniuersity College StationTx 77845USA Department of Environmental and Occupational Health School of Public Health Texas A&M UniversityCollege Station400 Bizzell St College StationTX 77843USA

The widespread use of pesticides has resulted in detectable residues throughout the environment,sometimes at concentrations well above regulatory ***,the development of safe,effective,field-practical,and economically feasible strategies to mitigate the effects of pesticides is *** is an organophosphorus herbicide that is degraded to aminomethylphosphonic acid(AMPA),a toxic and persistent metabolite that can accumulate in soil and sediment and translocate to *** this study,we investigated the binding efficacy of activated carbon(AC)and calcium montmorillonite(CM)clay to decrease AMPA bioavailability from soil and AMPA translocation to *** isotherms and thermodynamic studies on AC and CM were conducted and showed tight binding(enthalpy values>-20 k j/mol)for AMPA with high capacities(0.25 mol/kg and 0.38 mol/kg,respectively),based on derivations from the Langmuir model.A hydra assay was utilized to indicate toxicity of AMPA and the inclusion of 1%AC and CM both resulted in 90%protection of the hydra(**p≤0.01).Further studies in glyphosate-contaminated soil showed that AC and CM significantly reduced AMPA bioavailability by 53%and 44%,*** in genetically modified(GM)corn showed a conversion of glyphosate to AMPA in roots and sprouts over a 10-day exposure *** of AC and CM reduced AMPA residues in roots and sprouts by 47%-61%.These studies collectively indicate that AC and CM are effective sorbents for AMPA and could be used to reduce AMPA bioavailability from soil and AMPA residues in GM corn plants.

关键词： Glyphosate AMPA Activated carbon Calcium montmorillonite Sorbent

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Microphysiological systems for solid tumor immunotherapy:opportunities and challenges

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Microsystems & Nanoengineering 2023年第6期9卷 77-106页

作者： sara Abizanda-Campo María Virumbrales-Muñoz Mouhita Humayun Ines Marmol David j.Beebe Ignacio Ochoa sara Oliván jose M.Ayuso Department of Dermatology University of Wisconsin-MadisonMadisonWIUSA University of Wisconsin Carbone Cancer Center MadisonWIUSA Department of Biomedical Engineering University of WisconsinMadisonWIUSA Tissue Microenvironment Lab(TME lab) Aragón Institute of Engineering Research(I3A)University of ZaragozaZaragozaSpain Instituto de Investigación Sanitaria Aragón(IISA) ZaragozaSpain Centro Investigación Biomédica en Red.Bioingeniería Biomateriales y Nanomedicina(CIBER-BBN)ZaragozaSpain Department of Obstetrics and Gynecology University of Wisconsin-MadisonMadisonWIUSA Department of Biological Engineering Massachusetts Institute of Technology CambridgeCambridgeMAUSA Department of Pathology&Laboratory Medicine University of WisconsinMadisonWIUSA

Immunotherapy remains more effective for hematologic tumors than for solid *** of the main challenges to immunotherapy of solid tumors is the immunosuppressive microenvironment these tumors generate,which limits the cytotoxic capabilities of immune effector cells(e.g.,cytotoxic T and natural killer cells).This microenvironment is characterized by hypoxia,nutrient starvation,accumulated waste products,and acidic ***-hijacked cells,such as fibroblasts,macrophages,and T regulatory cells,also contribute to this inhospitable microenvironment for immune cells by secreting immunosuppressive cytokines that suppress the antitumor immune response and lead to immune ***,there is a strong interest in developing new drugs and cell formulations that modulate the tumor microenvironment and reduce tumor cell immune *** systems(MPSs)are versatile tools that may accelerate the development and evaluation of these therapies,although specific examples showcasing the potential of MPSs remain *** in microtechnologies have led to the development of sophisticated microfluidic devices used to recapitulate tumor *** resulting models,also known as microphysiological systems(MPSs),are versatile tools with which to decipher the molecular mechanisms driving immune cell antitumor cytotoxicity,immune cell exhaustion,and immune cell exclusion and to evaluate new targeted ***,we review existing microphysiological platforms to study immuno-oncological applications and discuss challenges and opportunities in the field.

关键词： immunotherapy versatile solid

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Organotypic hippocampal slices,an emerging tool to model synucleinopathies

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Neural Regeneration Research 2021年第5期16卷 999-1000页

作者： sara Elfarrash Poul Henning jensen Department of Physiology Faculty of MedicineMansoura UniversityMansouraEgypt DANDRITE‑Danish Research Institute of Translational Neuroscience and Department of Biomedicine Aarhus UniversityAarhusDenmark

Parkinson’s disease(PD)is the second most common neurodegenerative disease after Alzheimer’s *** has been traditionally considered a motoric disorder characterized by tremor,rigidity and bradykinesia,however it is now settled that PD also comprises a range of non-motor symptoms like hyposmia,sleep disturbances and cognitive impairments(Tysnes and Storstein,2017).

关键词： Alzheimer impairment settled

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