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Rates and processes affecting As speciation and mobility in lake sediments during aging

Journal of Environmental Sciences 2018年第4期30卷 338-347页

作者： Alan Lock Dirk Wallschlager nelson belzile Graeme Spiers Celine Gueguen Environmental and Life Sciences Graduate Program Trent University School of the Environment Department of Chemistry and Water Quality CentreTrent University Department of Chemistry Laurentian University School of the Environment Departments of Earth Sciences and BiologyLaurentian University School of the Environment and Chemistry Department Trent University

Sediments from an arsenic（As） contaminated groundwater vent site were used to investigate As（ Ⅲ） binding, transformation and redistribution in native and iron oxide amended lake sediments using aging spiked batch reactions and a sequential extraction procedure that maintains As（V） and As（ Ⅲ） speciation. In the native sediments, fractionation analysis revealed that 10% of the spiked As（ Ⅲ） remained intact after a 32-day aging experiment and was predominantly adsorbed to the strongly sorbed（NH4H2PO4 extractable） and amorphous Fe oxide bound（H3PO4 extractable） fractions. Kinetic modelling of the experimental results allowed identifying the dominant reaction path for depletion of dissolved As（ Ⅲ） to As（ Ⅲ）absorbed on to the solid phase, followed by oxidation in the solid phase. Arsenite was initially adsorbed primarily to the easily exchangeable fraction（（NH4）2SO4 extractable）, then rapidly transformed into As（V） and redistributed to the strongly sorbed and amorphous Fe oxide bound fractions. Oxidation of As（ Ⅲ） in recalcitrant fractions was less efficient. The iron oxide amendments illustrated the controls that iron oxides can have on As（ Ⅲ） binding and transformation rates. In goethite amended samples As（ Ⅲ） oxidation was faster and primarily occurred in the strongly sorbed and amorphous Fe oxide bound fractions. In these samples,19.3 μg Mn was redistributed（compared to the native sediment） from the easily exchangeable and crystalline Fe oxide bound fractions to the strongly sorbed and amorphous Fe oxide bound fractions, indicating that goethite may act as a catalyst for Mn（Ⅱ） oxidation, thereby producing sorbed Mn（ Ⅲ/Ⅳ ）, which then appears to be involved in rapidly oxidizing As（ Ⅲ）.

关键词： Arsenite Oxidation Fractionation Redistribution Modelling

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Function and dysfunction of GEMIN5:understanding a novel neurodevelopmental disorder

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Neural Regeneration Research 2024年第11期19卷 2377-2386页

作者： Charles H.nelson Udai B.Pandey Department of Pediatrics Division of Child NeurologyChildren’s Hospital of PittsburghUniversity of Pittsburgh Medical CenterPittsburghPAUSA Children’s Neuroscience Institute Children’s Hospital of PittsburghUniversity of Pittsburgh Medical CenterPittsburghPAUSA

The recent identification of a neurodevelopmental disorder with cerebellar atrophy and motor dysfunction(NEDCAM)has resulted in an increased interest in GEMIN5,a multifunction RNA-binding protein.As the largest member of the survival motor neuron complex,GEMIN5 plays a key role in the biogenesis of small nuclear ribonucleoproteins while also exhibiting translational regulatory functions as an independent protein.Although many questions remain regarding both the pathogenesis and pathophysiology of this new disorder,considerable progress has been made in the brief time since its discovery.In this review,we examine GEMIN5 within the context of NEDCAM,focusing on the structure,function,and expression of the protein specifically in regard to the disorder itself.Additionally,we explore the current animal models of NEDCAM,as well as potential molecular pathways for treatment and future directions of study.This review provides a comprehensive overview of recent advances in our understanding of this unique member of the survival motor neuron complex.

关键词： cerebellar atrophy GEMIN5 neurodevelopmental disorder neurological disease SMN complex

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Recent Developments in Metallic Degradable Micromotors for Biomedical and Environmental Remediation Applications

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Nano-Micro Letters 2024年第3期16卷 1-35页

作者： Sourav Dutta Seungmin Noh Roger Sanchis Gual Xiangzhong Chen Salvador Pané Bradley J.nelson Hongsoo Choi Department of Robotics and Mechatronics Engineering Daegu Gyeongbuk Institute of Science and Technology(DGIST)Daegu 42988Republic of Korea DGIST‑ETH Microrobotics Research Center DGISTDaegu 42988Republic of Korea Multi‑Scale Robotics Lab Institute of Robotics and Intelligent SystemsETH Zurich8092 ZurichSwitzerland Institute of Optoelectronics State Key Laboratory of Photovoltaic Science and TechnologyShanghai Frontiers Science Research Base of Intelligent Optoelectronics and PerceptionFudan UniversityShanghai 200433People’s Republic of China

Synthetic micromotor has gained substantial attention in biomedicine and environmental remediation.Metal-based degradable micromotor composed of magnesium(Mg),zinc(Zn),and iron(Fe)have promise due to their nontoxic fuel-free propulsion,favorable biocompatibility,and safe excretion of degradation products Recent advances in degradable metallic micromotor have shown their fast movement in complex biological media,efficient cargo delivery and favorable biocompatibility.A noteworthy number of degradable metal-based micromotors employ bubble propulsion,utilizing water as fuel to generate hydrogen bubbles.This novel feature has projected degradable metallic micromotors for active in vivo drug delivery applications.In addition,understanding the degradation mechanism of these micromotors is also a key parameter for their design and performance.Its propulsion efficiency and life span govern the overall performance of a degradable metallic micromotor.Here we review the design and recent advancements of metallic degradable micromotors.Furthermore,we describe the controlled degradation,efficient in vivo drug delivery,and built-in acid neutralization capabilities of degradable micromotors with versatile biomedical applications.Moreover,we discuss micromotors’efficacy in detecting and destroying environmental pollutants.Finally,we address the limitations and future research directions of degradable metallic micromotors.

关键词： Magnesium Zinc Iron Biodegradable microrobot Biomedical Environmental

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A neural branch-and-price for truck scheduling in cross-docks

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Science China Mathematics 2024年第6期67卷 1341-1358页

作者： Rahimeh Neamatian Monemi Shahin Gelareh nelson Maculan Wei-Kun Chen Sharkey Predictim Globe Villeneuve d’Ascq59650France Département R&T IUT de BéthuneUniversitéd’ArtoisBéthuneF-62000France Federal University of Rio de Janeiro COPPE-PESCRio de JaneiroRJ 21941-972Brazil School of Mathematics and Statistics Beijing Institute of TechnologyBeijing100081China

In this paper,we address the complex problem of dock-door assignment and truck scheduling within cross-docking operations.This is a problem that requires frequent resolution throughout the operational day,as disruptions often invalidate the optimal plan.Given the problem's highly combinatorial nature,finding an optimal solution demands significant computational time and resources.However,the distribution of data across problem instances over a lengthy planning horizon remains consistently stable,with minimal concern regarding distribution shift.These factors collectively establish the problem as an ideal candidate for a learn-to-optimize solution strategy.We propose a Dantzig-Wolfe reformulation,solving it via both a conventional branch-and-price approach and a neural branch-and-price approach,the latter of which employs imitation learning.Additionally,we introduce some classes of valid inequalities to enhance and refine the pricing problem through a branch-and-cut scheme.Our computational experiments demonstrate that this methodology is not only feasible but also presents a viable alternative to the traditional branch-and-price algorithms typically utilized for such challenges.

关键词： cross-docking MILP modeling Dantzig-Wolfe decomposition graph convolutional network

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The Cloud Model for Climate Change

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International Journal of Geosciences 2024年第5期15卷 366-395页

作者： Michael nelson David B. nelson Retired Pleasanton CA USA

In 1995, the Intergovernmental Panel on Climate Change (IPCC) released a thermodynamic model based on the Greenhouse Effect, aiming to forecast global temperatures. This study delves into the intricacies of that model. Some interesting observations are revealed. The IPCC model equated average temperatures with average energy fluxes, which can cause significant errors. The model assumed that all energy fluxes remained constant, and the Earth emitted infrared radiation as if it were a blackbody. Neither of those conditions exists. The IPCC’s definition of Climate Change only includes events caused by human actions, excluding most causes. Satellite data aimed at the tops of clouds may have inferred a high Greenhouse Gas absorption flux. The model showed more energy coming from the atmosphere than absorbed from the sun, which may have caused a violation of the First and Second Laws of Thermodynamics. There were unexpectedly large gaps in the satellite data that aligned with various absorption bands of Greenhouse Gases, possibly caused by photon scattering associated with re-emissions. Based on science, we developed a cloud-based climate model that complied with the Radiation Laws and the First and Second Laws of Thermodynamics. The Cloud Model showed that 81.3% of the outgoing reflected and infrared radiation was applicable to the clouds and water vapor. In comparison, the involvement of CO2 was only 0.04%, making it too minuscule to measure reliably.

关键词： Climate Change Greenhouse Gas CO2 Clouds Model Thermodynamics

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Decoupling CO₂ from Climate Change

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International Journal of Geosciences 2024年第3期15卷 246-269页

作者： Michael nelson David B. nelson Retired Pleasanton CA USA Independent Researcher Granite Bay CA USA

This study determines if there is a correlation between rising carbon dioxide levels and global warming. Historical data were reviewed from three different time periods spanning 500 million years. It showed that the curves and trends were too dissimilar to establish a connection. Observations from CO2/temp ratios showed that the CO2 and the temperature moved in opposite directions 42% of the time. Many ratios displayed zero or near zero values, reflecting a lack of response. As much as 87% of the ratios revealed negative or near zero values, which strongly negate a correlation. The infrared spectra showed the Greenhouse Gases had an exceptionally low absorption band between 11.67 μm to 9.1 μm, which is a zone called the infrared atmospheric window. Most of the Greenhouse Gases absorb little infrared inside that zone. And that zone is where the Earth’s surface emits almost all infrared radiation. Even with minimal absorbance, water vapor captures the most infrared radiation. It absorbs 84 times more than CO2, 407 thousand times more than methane, 452 thousand times more than ozone and 2.3 million times more than nitrous oxide. The Intergovernmental Panel on Climate Change (IPCC) and the United States EPA excluded water vapor because it was not associated with man-made activities. They reported that water vapor and clouds were simply feedback mechanisms from CO2. Clouds reflect radiation from the sun. The Northern Hemisphere is 2.7°F warmer than the Southern Hemisphere because of clouds. The world cloud cover has gone down 4.1% from 1982 to 2018. Calculations show that this could be responsible for 2.4°F of the 2.7°F. The research shows that most of the recent increase in temperature (89.9%) is because of fewer clouds.

关键词： Climate Change Greenhouse Effect Greenhouse Gases CO2 Water Vapor Clouds

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Seasonal variations of phosphorus species in the Tuohe River, China. Part Ⅰ. Sediments

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Journal of Oceanology and Limnology 2018年第6期36卷 1950-1961页

作者：徐青余晓平郭亚飞邓天龙 CHEN Yu-Wei nelson belzile Tianjin Key Laboratory of Marine Resources and Chemistry College of Chemical Engineering and Materials ScienceTianjin University of Sciences and Engineering School of Architecture and Civil Engineering Chengdu University Department of Chemistry and Biochemistry Laurentian University

Sediment cores were collected at an upstream site(Jintang) and a downstream site(Neijiang) in summer and winter in the Tuohe River, which is one of the five largest tributaries of the Changjiang(Yangtze) River in China. A sequential leaching procedure was applied to determine the concentrations of the different forms of solid phosphorus, including exchangeable phosphorus(Exc-P) as well as phosphorus associated with iron oxides(Fe-P), with aluminum oxides(Al-P), with apatite(Ca-P) and with the residual fraction(Res-P), as correlated with water content and total organic carbon. The seasonal variations and the vertical distributions of phosphorus species in sediments at both sampling sites demonstrated that: 1) total phosphorus(TP) in summer and winter were ranged between 1 313–2 330, 1 491–2 228 mg/kg in Jintang and 543–2 128, 603–1 175 mg/kg in Neijiang, respectively. It can predicated the pollution of TP in Jintang is serious than that in Neijiang both in summer and winter; 2) total inorganic phosphorus(TIP) was the dominant form of TP; 3) Ca-P was the main chemical forms of TIP in the sediments. Based on the profiles in sediments and bio-available phosphorus data, it revealed that bio-available phosphorus(BAP) represented only a minor portion(0.61%–3.59%) of TP, and the vertical distribution of soluble reactive phosphorus(SRP) in corresponding porewaters was more abundant in the upper layer of the sediment, which suggests that BAP may be converted to non-bioavailable phosphorus in deeper layer of the sediment of this dynamic system.

关键词： phosphorus species vertical distribution seasonal variation Tuohe River

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Decoding complexity: the need to enhance precision and streamline spatial understanding in neuroscience

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Neural Regeneration Research 2025年第3期20卷 801-802页

作者： Sameehan Mahajani Armita Salahi Brenda Gonzalez Charlotte nelson Frank Hsiung Biology&Applications Division NodexusSan JoseCAUSA

Neuroscience is the ultimate frontier in our quest for a comprehensive understanding of human behavior. Since its launch in 2009, the Human Connectome Project has emerged as a pioneering force, making heroic strides i... 详细信息

关键词： behavior frontier dating

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Determining the effective elastic thickness through cross-correlation between isostatic disturbances

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Geodesy and Geodynamics 2024年第3期15卷 241-251页

作者： nelson Ribeiro-Filho Cristiano Mendel Martins Raissa Moraes Baldez Ivaldevingles Rodrigues de Souza Júnior Franck Eitel Kemgang Ghomsi Instituto Federal do Pará(IFPA) AltamiraParáBrazil Universidade Federal do Pará(UFPA) BelemParáBrazil Nansen-Tutu Center for Marine Environmental Research Department of OceanographyUniversity of Cape TownSouth Africa Geodesy Research Laboratory National Institute of CartographyYaoundeCameroon

The elastic thickness parameter was estimated using the mobile correlation technique between the observed isostatic disturbance and the gravity disturbance calculated through direct gravimetric modeling. We computed the vertical flexure value of the crust for a specific elastic thickness using a given topographic dataset. The gravity disturbance due to the topography was determined after the calculation. A grid of values for the elastic thickness parameter was generated. Then, a moving correlation was performed between the observed gravity data(representing actual surface data) and the calculated data from the forward modeling. The optimum elastic thickness of the particular point corresponded to the highest correlation coefficient. The methodology was tested on synthetic data and showed that the synthetic depth closely matched the original depth, including the elastic thickness value. To validate the results, the described procedure was applied to a real dataset from the Barreirinhas Basin, situated in the northeastern region of Brazil. The results show that the obtained crustal depth is highly correlated with the depth from known models. Additionally, we noted that the elastic thickness behaves as expected, decreasing from the continent towards the ocean. Based on the results, this method has the potential to be employed as a direct estimate of crustal depth and elastic thickness for any region.

关键词： Isostasy Elastic thickness Isostatic disturbance Moho depth Cross-correlation

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SMXL5 attenuates strigolactone signaling in Arabidopsis thaliana by inhibiting SMXL7 degradation

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Molecular Plant 2024年第4期17卷 631-647页

作者： Qingtian Li Haiyang Yu Wenwen Chang Sunhyun Chang Michael Guzman Lionel Faure Eva-Sophie Wallner Heqin Yan Thomas Greb Lei Wang Ruifeng Yao David C.nelson Department of Botany and Plant Sciences University of CaliforniaRiversideRiversideCA 2521USA Yazhouwan National Laboratory Sanya 572025China Hainan Seed Industry Laboratory Sanya 57205China State Key Laboratory of Chemo/Biosensing and Chemometrics Hunan Provincial Key Laboratory of Plant Functional Genomics and Developmental RegulationCollege of BiologyHunan UniversityChangsha 410082China Key Laboratory of Seed Innovation Center for Agricultural Resources ResearchInstitute of Genetics and Developmental BiologyChinese Academy of SciencesShijiazhuangHebei 050021China University of Chinese Academy of Sciences Beijing 10004China School of the Sciences Biology DivisionTexas Woman’s UniversityDentonTX 76204USA Centre for Organismal Studies(COS) Heidelberg University6120 HeidelbergGermany

Hormone-activated proteolysis is a recurring theme of plant hormone signaling mechanisms.In strigolactone signaling,the enzyme receptor DWARF14(D14)and an F-box protein,MORE AXILLARY GROWTH2(MAX2),mark SUPPRESSOR OF MAX21-LIKE(SMXL)family proteins SMXL6,SMXL7,and SMXL8 for rapid degradation.Removal of these transcriptional corepressors initiates downstream growth responses.The homologous proteins SMXL3,SMXL4,and SMXL5,however,are resistant to MAX2-mediated degradation.We discovered that the smxl4 smxl5 mutant has enhanced responses to strigolactone.SMXL5 attenuates strigolactone signaling by interfering with AtD14-SMXL7 interactions.SMXL5 interacts with AtD14 and SMXL7,providing two possible ways to inhibit SMXL7 degradation.SMXL5 function is partially dependent on an ethylene-responsive-element binding-factor-associated amphiphilic repression(EAR)motif,which typically mediates interactions with the TOPLESS family of transcriptional corepressors.However,we found that loss of the EAR motif reduces SMXL5-SMXL7 interactions and the attenuation of strigolactone signaling by SMXL5.We hypothesize that integration of SMXL5 into heteromeric SMXL complexes reduces the susceptibility of SMXL6/7/8 proteins to strigolactone-activated degradation and that the EAR motif promotes the formation or stability of these complexes.This mechanism may provide a way to spatially or temporally fine-tune strigolactone signaling through the regulation of SMXL5 expression or translation.

关键词： Arabidopsis typically inhibiting

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