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Metamorphic disturbances of magnetite chemistry and the Sm-Nd isotopic system of reworked Archean iron formations from NE Brazil

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Geoscience Frontiers 2022年第5期13卷 227-241页

作者： Joice Dias de Moraes Pedro cordeiro Eduardo Abrahão Filho Juliana Rezende Oliveira carlos victor Rios da Silva Filho Instituto de Geociências Universidade de Brasília(UnB)70910-900 BrasíliaDFBrazil department of Mining Engineering Pontifical Catholic University of Chile7820436 SantiagoChile

Iron formations are valuable archives of sedimentary conditions and post-depositional ***,geochemical proxies commonly used to determine genetic characteristics can be variably modified during metamorphism and deformation,hampering their use as records of regional geological *** work focuses on strongly reworked magnetite-quartz-rich rocks from the São Josédo campestre Massif,one of the oldest fragments of preserved crust in South *** genetic classification of these magnetite-quartz-rich rocks is not straightforward because primary assemblages and textures were variably modified by granulite facies metamorphism during a regional Paleoproterozoic migmatization *** address genetic ambiguities,we analyzed their magnetite and pyroxene chemistry,wholerock geochemistry,and Sm-Nd *** chemistry indicates that pyroxene-poor iron formations(Type B)are low in trace elements such as Ti,Al,V,and Mn,suggesting a chemical similarity to iron formations *** contrast,magnetites from pyroxene-enriched Type A iron formations are rich in trace elements and more akin to magnetite crystallized from higher temperature systems,such as skarn and ***^(147)Sm/^(144)Nd of these rocks show substantial variation even at the outcrop scale,indicating a locally-controlled,highly heterogeneous mixture of Archean,Paleoproterozoic,and Neoproterozoic ***,our geochemical tools point out to heterogenous signatures of these magnetitequartz rocks and proxies compatible with both low and high-temperature conditions and age of deposition spanning sources from the Archean to the *** interpret that the studied São Josédo campestre magnetite-quartz rocks represent Archean iron formations with original magnetite chemistry and isotopic signatures variably modified by metamorphism and by at least one deformation-related hydrothermal *** results contrast with similar examples from china and Greenland where iron formation

关键词： Metamorphic disturbances of magnetite chemistry and the Sm-Nd isotopic system of reworked Archean iron formations from NE Brazil

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determination of urine-derived odorous compounds in a source separation sanitation system

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Journal of Environmental Sciences 2017年第2期29卷 240-249页

作者： Bianxia Liu Apostolos Giannis Ailu chen Jiefeng Zhang victor W.c.chang Jing-Yuan Wang .Residues and Resource Reclamation centre(R3c) Nanyang Environment and Water Research InstituteNanyang Technological University1 Cleantech LoopCleanTech OneSingapore 637141Singapore School of civil and Environmental Engineering Nanyang Technological University50 Nanyang AvenueSingapore 639798Singapore

Source separation sanitation systems have attracted more and more attention ***, separate urine collection and treatment could induce odor issues, especially in large scale application. In order to avoid such issues, it is necessary to monitor the odor related compounds that might be generated during urine storage. This study investigated the odorous compounds that emitted from source-separated human urine under different hydrolysis conditions. Batch experiments were conducted to investigate the effect of temperature, stale/fresh urine ratio and urine dilution on odor emissions. It was found that ammonia, dimethyl disulfide, allyl methyl sulfide and 4-heptanone were the main odorous compounds generated from human urine, with headspace concentrations hundreds of times higher than their respective odor thresholds. Furthermore, the high temperature accelerated urine hydrolysis and liquid–gas mass transfer, resulting a remarkable increase of odor emissions from the urine solution. The addition of stale urine enhanced urine hydrolysis and expedited odor emissions. On the contrary, diluted urine emitted less odorous compounds ascribed to reduced concentrations of odorant precursors. In addition,this study quantified the odor emissions and revealed the constraints of urine source separation in real-world applications. To address the odor issue, several control strategies are recommended for odor mitigation or elimination from an engineering perspective.

关键词： Odor emissions Volatile organic compounds(VOcs) Urine hydrolysis Source separation Gas chromatography mass spectrometry(Gc–MS)

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H pylori receptor MHc classⅡcontributes to the dynamic gastric epithelial apoptotic response

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World Journal of Gastroenterology 2006年第33期12卷 4689-4693页

作者： David A Bland Giovanni Suarez Ellen J Beswick Johanna c Sierra victor E Reyes the University of Texas Medical Branch at Galveston TX 77555-0366 United States

AIM： To investigate the role of MHc class Ⅱ in the modulation of gastric epithelial cell apoptosis induced by H pylori infection. METHODS： After stimulating a human gastric epithelial cell line with bacteria or agonist antibodies specific for MHc class Ⅱ and cD95, the quantitation of apoptotic and anti-apoptotic events, including caspase activation, BcL-2 activation, and FADD recruitment, was performed with a fluorometric assay, a cytometric bead array, and confocal microscopy, respectively. RESULTS： Pretreatment of N87 cells with the anti-MHc class ⅡIgM antibody RFD1 resulted in a reduction in global caspase activation at 24 h of H pylori infection. When caspase 3 activation was specifically measured, crosslinking of MHc class Ⅱ resulted in markedly reduced caspase activation, while simple ligation of MHc class Ⅱ did not. crosslinking of MHc class Ⅱ also resulted in an increased activation of the anti-apoptosis molecule BcL-2 compared to simple ligation. confocal microscope analysis demonstrated that the pretreatment of gastric epithelial cells with a crosslinking anti-MHc class Ⅱ IgM blocked the recruitment of FADD to the cell surface. cONcLUSION： The ability of MHc class Ⅱ to modulate gastric epithelial apoptosis is at least partially dependent on its crosslinking. The crosslinking of this molecule has anti-apoptotic effects during the earlier time points of Hpylori infection. This effect is possibly mediated by the ability of MHc class Ⅱ to modulate the activation of the pro-apoptotic receptor Fas by blocking the recruitment of the accessory molecule FADD, and this delay in apoptosis induction could allow for prolonged cytokine secretion by Hpylori-infected gastric epithelial cells.

关键词： Hpylori Epithelium Apoptosis class Ⅱ MHc

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巴黎圣母院

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2016年

作者： victor hugo[]

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A self-stabilised walking gait for humanoid robots based on the essential model with internal states

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IET cyber-Systems and Robotics 2022年第4期4卷 283-297页

作者： Qiuyue Luo christine chevallereau Yongsheng Ou Jianxin Pang victor de-León-Gómez Yannick Aoustin Shenzhen Institutes of Advanced Technology Chinese Academy of SciencesShenzhenChina Research Institute of UBTech Robotics ShenzhenChina Laboratoire des Sciences du Numerique de Nantes(LS2N) CNRSCentrale NantesNantes UniversitéNantesFrance FcA at the Univerdidad Autónoma de coahuila TorreónMéxico

Walking stability is one of the key issues for humanoid robots.A self-stabilised walking gait for a full dynamic model of humanoid robots is *** simplified models,that is,the linear inverted pendulum model and variable-length inverted pendulum model,self-stabilisation of walking gait can be obtained if virtual constraints are properly *** result is extended to the full dynamic model of humanoid robots by using an essential dynamic model,which is developed based on the zero dynamics *** the proposed method,a robust stable walking for a humanoid robot is achieved by adjusting the step timing and landing position of the swing foot automatically,following its intrinsic dynamic *** exempts the robot from the time-consuming high-level control approaches,especially when a full dynamic model is *** different walking patterns/features(i.e.,the swing foot motion,the vertical centre of mass motion,the switching manifold configuration,etc.)affect the stability of the walking gait is *** are conducted on robots Romeo and TALOS to support the results.

关键词： dynamic stability humanoid and bipedal locomotion passive walking

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High efficiency second harmonic generation of nanojoule-level femtosecond pulses in the visible based on BiBO

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High Power Laser Science and Engineering 2019年第1期7卷 82-89页

作者： Mario Galletti hugo Pires victor Hariton celso Paiva Joao Swen Künzel Marco Galimberti Goncalo Figueira GoLP/Instituto de Plasmas e Fusao Nuclear Instituto Superior Técnico Universidade de Lisboa central Laser Facility Science and Technology Facilities Council Rutherford Appleton Laboratory Harwell Science and Innovation Campus

We demonstrate high efficiency second harmonic generation(SHG) of near infrared femtosecond pulses using a BiB3 O6 crystal in a single-pass tight focusing geometry setup. A frequency doubling efficiency of 63% is achieved, which is,to the best of our knowledge, the highest value ever reported in the femtosecond regime for such low energy(nJ-level)pumping pulses. Theoretical analyses of the pumping scheme focusing waist and the SHG efficiency are performed, by numerically solving the three wave mixing coupled equations in the plane-wave scenario and by running simulations with a commercial full 3 D c.de. Simulations show a good agreement with the experimental data regarding both the efficiency and the pulse spectral profile. The simulated SHG pulse temporal profile presents the characteristic features of the group velocity mismatch broadening in a ‘thick' crystal.

关键词： nonlinear process second harmonic generation pumping scheme parametric amplification/oscillators high power laser

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Participatory Early Warning Systems: Youth, citizen Science,and Intergenerational Dialogues on Disaster Risk Reduction in Brazil

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International Journal of Disaster Risk Science 2017年第4期8卷 390-401页

作者： victor Marchezini Rachel Trajber Dbora Olivato Viviana Aguilar Muoz Fernando de Oliveira Pereira Andra Eliza Oliveira Luz cemaden–National Early Warning and Monitoring center of Natural Disasters Distrito de Eugênio de MeloSo JosDos Campos

Building national people-centered early warning systems(EWS) is strongly recommended by the United Nations International Strategy for Disaster Reduction(UNISDR). Most of the scientific literature is critical of the conventional view of EWS as a linear model with a topdown approach, in which technological features are given more attention than human factors. It is argued that EWS should be people-centered, and used for risk prevention,with an emphasis on resilience, rather than only being triggered when a hazard occurs. However, both the UNISDR and the literature fail to say how a people-centered EWS should be built, and what steps are needed to put EWS into effect. This article examines the obstacles and measures required to promote people-centered EWS,with a focus on the situation in Brazil. After assessing the institutional vulnerability of EWS, we analyze some measures that can be taken to reduce institutional vulnerability,based on experiences with a participatory citizen science educational project that involved high school *** guidelines are developed for adopting a bottom-up approach towards achieving the four elements of EWS—risk knowledge, monitoring, communication of warnings,and response capability—with the help of school curricula.

关键词： Brazil capacity building citizen science Disaster risk reduction Early warning systems Resilient schools

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Effect of homogenization process on the hardness of Zn-Al-cu alloys

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International Journal of Minerals,Metallurgy and Materials 2015年第10期22卷 1076-1081页

作者： Jose D.Villegas-cardenas Maribel L.Saucedo-Munoz victor M.Lopez-Hirata Antonio de Ita-de la Torre Erika O.Avila-Davila Jorge Luis Gonzalez-Velazquez department of Metallurgy and Materials Instituto Politecnico Nacional(IPN-ESIQIE)Mexico City 07300Mexico department of Industrial Engineering Universidad Politecnica del Valle de MexicoMexico CityMexico department of Materials Universidad Autonoma Metropolitana(UAM)Unidad AzcapotzalcoMexico

The effect of a homogenizing treatment on the hardness of as-cast Zn–Al–cu alloys was investigated. Eight alloy compositions were prepared and homogenized at 350 °c for 180 h, and their Rockwell 'B' hardness was subsequently measured. All the specimens were analyzed by X-ray diffraction and metallographically prepared for observation by optical microscopy and scanning electron microscopy. The results of the present work indicated that the hardness of both alloys(as-cast and homogenized) increased with increasing Al and cu contents; this increased hardness is likely related to the presence of the θ and τ′ phases. A regression equation was obtained to determine the hardness of the homogenized alloys as a function of their chemical composition and processing parameters, such as homogenization time and temperature, used in their preparation.

关键词： zinc–aluminum–copper alloys casting hardness homogenization phases microstructure

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Implementation of an analogue model of a memristor based on a light-dependent resistor

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chinese Physics B 2012年第10期21卷 500-507页

作者：王晓媛 Andrew L.Fitch Herbert H.c.Iu victor Sreeram 齐维贵 School of Electrical Engineering Harbin Institute of Technology School of Electrical Electronicand Computer EngineeringThe University of Western Australia 35 Stirling HighwayCrawleyWA 6009Australia

In this paper,an analogue model of a memristor using a light-dependent resistor(LDR) is *** model can be simplified into two parts:a control circuit and a variable *** can be used to easily verify theoretical presumptions about the switching properties of *** LDR-based memristor model can also be used in both simulations and experiments for future research into memristor *** paper includes mathematical models,simulations,and experimental results.

关键词： analogue model light-dependent resistor memristor simulator

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Tunable electrochemistry of gold-silver alloy nanoshells

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Nano Research 2018年第12期11卷 6336-6345页

作者： Lorenzo Russo victor Puntes Arben Merkoci catalan Institute of Nanoscience and Nanotechnology (IcN2) CSIC and BISTCampus UABBellaterra08193BarcelonaSpain Universitat Autonoma de Barcelona (UAB) Campus UABBellaterra08193BarcelonaSpain Vail d'Hebron Institut de Recerca (VHIR) 08035BarcelonaSpain Institucio catalana de Recerca i Estudis Avancats (IcREA) P Llub Companys 2308010BarcelonaSpain

The widespread and increasing interest in enhancing biosensing technologies by increasing their sensitivities and lowering their costs has led to the exploration and application of complex nanomaterials as signal transducers and enhancers. In this work, the electrochemical properties of monodispersed AuAg alloy nanoshells (NSs) with finely tunable morphology, composition, and size are studied to assess their potential as electroactive labels. The controlled corrosion of their silver content, caused by the oxidizing character of dissolved oxygen and chlorides of the electrolyte, allows the generation of a reproducible electrochemical signal that is easily measurable through voltammetric techniques. Remarkably, the underpotential deposition of dissolved Ag+ catalyzed on AuAg NS surfaces is observed and its dependence on the nanoparticle morphology, size, and elemental composition is studied, revealing a strong correlation between the relative amounts of the two metals. The highest catalytic activity is found at Au/Ag ratios higher than ≈ 10, showing how the synergy between both metals is necessary to trigger the enhancement of Ag+ reduction. The ability of AuAg NSs to generate an electrocatalytic current without the need for any strong acid makes them an extremely promising material for biosensing applications.

关键词： Au nanoshells nanoparticles surface chemistry underpotential deposition

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