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Lead isotope evolution of the Central European upper mantle:Constraints from the Bohemian Massif

Geoscience Frontiers 2020年第3期11卷 925-942页

作者： Simona Krmíckova lukas Krmícek Rolf L.Romer Jaromír Ulrych Department of Geological Sciences Faculty of ScienceMasaryk UniversityKotlarska 2CZ-61137BrnoCzech Republic Institute of Geology of the Czech Academy of Sciences Rozvojova 269CZ-16502Prague 6Czech Republic Brno University of Technology Faculty of Civil EngineeringAdMaS CentreVeverí95CZ-60200BrnoCzech Republic Deutsches GeoForschungsZentrum GFZ TelegrafenbergD-14473PotsdamGermany

The Pb isotope composition of the upper mantle beneath Central Europe is heterogeneous due to the subduction of regionally contrasting material during the variscan and Alpine *** variscan to Cenozoic mantlederived melts allow mapping this heterogeneity on a regional scale for the last ca.340 *** Cretaceous and Cenozoic anorogenic magmatic rocks of the Bohemian Massif(lamprophyres,volcanic rocks of basanite/tephrite and trachyte/phonolite series) concentrate mostly in the Eger *** ultramafic lamprophyres yielded the most radiogenic Pb isotope signatures reflecting a maximum contribution from metasomatised lithospheric mantle,whereas Tertiary alkaline lamprophyres originated from mantle with less radiogenic ^(206)Pb/^(204)b ratios suggesting a more substantial modification of lithospheric source by interaction with asthenosphericderived *** volcanic rocks of the basanite/tephrite and trachyte/phonolite series define a linear mixing trend between these components,indicating dilution of the initial lithospheric mantle signature by upwelling asthenosphere during *** Pb isotope composition of Late Cretaceous and Cenozoic magmatic rocks of the Bohemian Massif follows the same Pb growth curve as variscan orogenic lamprophyres and lamproites that formed during the collision between Laurussia,Gondwana,and associated *** implies that the crustal Pb signature in the post-variscan mantle is repeatedly sampled by younger anorogenic *** Cenozoic mantle-derived rocks of Central Europe show similar Pb isotope ranges as the Bohemian Massif.

关键词： Lead isotopes Lamprophyres volcanic rocks Mantle components Bohemian massif variscan orogeny

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Off-the-shelf deep learning is not enough,and requires parsimony,Bayesianity,and causality

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npj Computational Materials 2021年第1期7卷 133-138页

作者： Rama K.vasudevan Maxim Ziatdinov lukas v.cek Sergei.v.Kalinin Center for Nanophase Materials Sciences Oak RidgeTN 37831USA Computational Sciences and Engineering Division Oak RidgeTN 37831USA Materials Science and Technology Division Oak Ridge National LaboratoryOak RidgeTN 37831USA Present address:Bayer St.LouisMO 63141USA

Deep neural networks(‘deep learning’)have emerged as a technology of choice to tackle problems in speech recognition,computer vision,finance,***,adoption of deep learning in physical domains brings substantial challenges stemming from the correlative nature of deep learning methods compared to the causal,hypothesis driven nature of modern *** argue that the broad adoption of Bayesian methods incorporating prior knowledge,development of solutions with incorporated physical constraints and parsimonious structural descriptors and generative models,and ultimately adoption of causal models,offers a path forward for fundamental and applied research.

关键词： learning enough finance

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Corrosion Behavior of AZ31 Magnesium Alloy in Highly Alkaline Environment

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Acta Metallurgica Sinica(English Letters) 2017年第4期30卷 367-375页

作者： Somi Doja lukas Bichler Simon Fan School of Engineering University of British ColumbiaOkanagan 3333 University Way Kelowna BC V1V 1VTCanada ZincNyx Energy Solutions Vancouver BC V6P 6T3 Canada

Industrial components made with a magnesium-aluminum alloy AZ31 are often used in diverse engineering applications where component weight, strength, and durability are critical. Similarly as other Mg alloys, however, the AZ31 is susceptible to corrosion in alkaline environments. In this work, corrosion of commercial grade AZ31 alloy plate was examined in potassium hydroxide （KOH） using immersion and potentiodynamic studies. The results suggest that the concentration of A1 and Mn in the alloy may govern the kinetics of micro-galvanic corrosion and the initiation of corrosion pits. Further, trace amounts of Ni in the AZ31 alloy were seen to enable formation of Ni（OH）2 surface layer, which may have further accelerated alloy corrosion due to its cracking and void coalescence. The effect of pH on the corrosion behavior of AZ31 was studied with reference to Pourbaix diagrams.

关键词： Magnesium alloy AZ31 KOH

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Carbon monoxide production using a steel mill gas in a combined chemical looping process

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Journal of Energy Chemistry 2022年第5期31卷 811-825页

作者： varun Singh lukas C.Buelens Hilde Poelman Mark Saeys Guy B.Marin vladimir v.Galvita Laboratory for Chemical Technology Technologiepark 125B-9052 GhentBelgium

Up to 9% of the global CO_(2) emissions come from the iron and steel industry. Here, a combined chemical looping process to produce CO, a building block for the chemical industry, from the CO_(2) -rich blast furnace gas of a steel mill is proposed. This cyclic process can make use of abundant Fe_(3)O_(4) and CaO as solid oxygen and CO_(2) carriers at atmospheric pressure. A proof of concept was obtained in a laboratory-scale fixed bed reactor with synthetic blast furnace gas and Fe_(3)O_(4) /CaO = 0.6 kg/kg. CO production from the proposed process was investigated at both isothermal conditions(1023 K) and upon imposing a temperature program from 1023 to 1148 K. The experimental results were compared using performance indicators such as CO yield, CO space time yield, carbon recovery of the process, fuel utilisation, and solids’ *** temperature-programmed CO production resulted in a CO yield of 0.056 ± 0.002 mol per mol of synthetic blast furnace gas at an average CO space time yield of 7.6 mmol kgFe^(-1) s^(-1) over 10 cycles, carbon recovery of 48% ± 1%, fuel utilisation of 23% ± 2%, and an average calcium oxide and iron oxide utilisation of 22% ± 1% and 11% ± 1%. These experimental performance indicators for the temperature-programmed CO production were consistently better than those of the isothermal implementation mode by 20% to 35%. Over 10 consecutive process cycles, no significant losses in CO yield were observed in either implementation mode. Process simulation was carried out for 1 million metric tonnes per year of equivalent CO_(2) emissions from the blast furnace gas of a steel mill to analyse the exergy losses in both modes of operation. Comparison of the exergy efficiency of the temperature-programmed process to the isothermal process showed that the former is more efficient because of the higher CO concentration achievable,despite 20% higher exergy losses caused by heat transfer required to change temperature.

关键词： Steel industry CO_(2)capture Calcium oxide CO_(2)sorbent Reverse water gas shift Circular economy Process intensification

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Carbon nanotube and graphene reinforced magnesium matrix composites:A state-of-the-art review

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镁合金学报(英文) 2023年第6期11卷 1825-1905页

作者： Lava Kumar Pillari Kyle Lessoway lukas Bichler School of Engineering The University of British Columbia-OkanaganKelownaBC V1V 1V7Canada

Magnesium(Mg)composites reinforced with carbon-based nanomaterial(CBN)often exhibit low density,enhanced strength,good conductivity,improved wear resistance,and excellent biocompatibility when compared to current industry Mg *** review aims to critically evaluate recent developments in Mg-CBN composites and is divided into five sections:First,a brief introduction to Mg-CBN composites is provided,followed by a discussion of different fabrication techniques for these composites,including powder metallurgy,casting,friction stir processing,and selective laser melting.A particular focus is on the current processing challenges,including dispersion strategies to create homogeneous Mg-CBN *** effect of processing on the quantifying disorder in CBNs and distinguishing different sp2carbon materials is also ***,the effect of CBN on various properties of Mg-CBN composites is thoroughly analyzed,and the strengthening efficiency of CNTs and graphene in the Mg matrix is ***,the potential applications of Mg-CBN composites in various industries are proposed,followed by a summary and suggestions for future research directions in the field of Mg-CBN composites.

关键词： Magnesium Carbon nanotubes(CNTs) Graphene Nanocomposites Processing Mechanical properties

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Thermodynamics of order and randomness in dopant distributions inferred from atomically resolved imaging

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npj Computational Materials 2021年第1期7卷 397-405页

作者： lukas v.cek Shize Yang Yongji Gong Pulickel Ajayan Wu Zhou Matthew FChisholm Maxim Ziatdinov Rama K.vasudevan Sergei v.Kalinin Materials Science and Technology Division Oak Ridge National LaboratoryOak RidgeTNUSA Joint Institute for Computational Sciences University of TennesseeKnoxvilleOak RidgeTNUSA Center for Functional Nanomaterials Brookhaven National LaboratoryBrookhavenNYUSA School of Materials Science and Engineering Beihang UniversityBeijingChina Department of Materials Science and NanoEngineering Rice UniversityHoustonTXUSA Center for Nanophase Materials Sciences Oak Ridge National LaboratoryOak RidgeTNUSA

Exploration of structure-property relationships as a function of dopant concentration is commonly based on mean field theories for solid ***,such theories that work well for semiconductors tend to fail in materials with strong correlations,either in electronic behavior or chemical *** these cases,the details of atomic arrangements are generally not explored and *** knowledge of the generative physics and chemistry of the material can obviate this problem,since defect configuration libraries as stochastic representation of atomic level structures can be generated,or parameters of mesoscopic thermodynamic models can be *** obtain such information for improved predictions,we use data from atomically resolved microscopic images that visualize complex structural correlations within the system and translate them into statistical mechanical models of structure *** the significant uncertainties about the microscopic aspects of the material’s processing history along with the limited number of available images,we combine model optimization techniques with the principles of statistical hypothesis *** demonstrate the approach on data from a series of atomically-resolved scanning transmission electron microscopy images of Mo_(x)Re_(1-x)S_(2) at varying ratios of Mo/Re stoichiometries,for which we propose an effective interaction model that is then used to generate atomic configurations and make testable predictions at a range of concentrations and formation temperatures.

关键词： atomic resolved dopant

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Magnetic Neutral Points and Electric Lines of Force in Strong Gravity of a Rotating Black Hole

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International Journal of Astronomy and Astrophysics 2013年第3期3卷 18-24页

作者： v.Karas O.Kopácek D.Kunneriath Astronomical Institute Academy of SciencesPragueCzech Republic

Magnetic field can be amplified and twisted near a supermassive black hole residing in a galactic nucleus. At the same time magnetic null points develop near the horizon. We examine a large-scale oblique magnetic field near a rotating (Kerr) black hole as an origin of magnetic layers, where the field direction changes abruptly in the ergosphere region. In consequence of this, magnetic null points can develop by purely geometrical effects of the strong gravitational field and the frame-dragging mechanism. We identify magnetic nulls as possible sites of magnetic reconnection and suggest that particles may be accelerated efficiently by the electric component. The situation we discuss is relevant for starving nuclei of some galaxies which exhibit episodic accretion events, namely, Sagittarius A* black hole in our Galaxy.

关键词： Galaxies:Nuclei Galaxy:Center Black Hole Physics Magnetic Fields

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Evaluation of the expression of sperm proteins in normozoospermic and asthenozoospermic men using monoclonal antibodies

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Asian Journal of Andrology 2016年第1期18卷 108-113页

作者： Jana Capkova Alena Kubatova lukas Ded Olina Tepla Jana Peknicova Laboratory of Reproductive Biology Institute of Biotechnology Academy of Sciences of the Czech Republic v. v. i. Prague Czech Republic Clinic Center IvF ISCARE Prague Czech Republic

Recent studies have shown that infertility affects estimated 15% of all couples. Male infertility is the primary or contributory cause in 60% of these cases. Consequently, the application of assisted reproduction is increasing. These methods could benefit from an extended evaluation of sperm quality. For this reason, we analyzed sperm proteins from 30 men with normal spermiograms and 30 men with asthenozoospermia. Ejaculates of both groups were tested by flow cytometry （FCM） and fluorescence with a set of well-characterized anti-human sperm Hs-monoclonal antibodies （MoAbs）, which were generated in our laboratory. No statistically significant differences were found between normospermics and asthenospermics in the expression of the sperm surface protein clusterin, evaluated with Hs-3 MoAb, and semenogelin, evaluated with Hs-9 MoAb. However, FCM revealed quantitative differences in the acrosomal proteins between normozoospermic and asthenozoospermic men, namely, in glyceraldehyde-3-phosphate dehydrogenase, evaluated with Hs-8 MoAb, valosin-containing protein, evaluated with Hs-14 MoAb, and ATP synthase （cAMP-dependent protein kinase II, PRKAR2A）, evaluated with MoAb Hs-36. Asthenozoospermic men displayed a highly reduced expression of intra-acrosomal proteins, with a likely decrease in sperm quality, and thus a negative impact on successful reproduction. Asthenozoospermia seems to be a complex disorder involving intra-acrosomal proteins.

关键词： asthenozoospermia flow cytometry fluorescence microscopy monoclonal antibodies sperm proteins

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Sequence-sorted redox-switchable hetero[3]rotaxanes

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Organic Chemistry Frontiers 2022年第1期9卷 64-74页

作者： Marius Gaedke Henrik Hupatz Felix Witte Susanne M.Rupf Clara Douglas Hendrik v.Schröder lukas Fischer Moritz Malischewski Beate Paulus Christoph A.Schalley Institut für Chemie und Biochemie der Freien Universität Berlin Arnimallee 2014195 BerlinGermany Institut für Chemie und Biochemie der Freien Universität Berlin Arnimallee 2214195 BerlinGermany Institut für Chemie und Biochemie der Freien Universität Berlin Fabeckstr.34/3614195 BerlinGermany

From a library of five crown ether macrocycles with different ring sizes and redox-active moieties,such as tetrathiafulvalene(TTF)and naphthalene dimiide(NDI),directional heterocircuit[3]rotaxanes were *** an axle with two binding sites with different steric accessibility,the concept of integrative self-sorting was applied to program the sequence of functional units in heteropseudo[3]*** on binding strength and ring size of the smaller macrocycles,different heteropseudo[3]rotaxane selectivities and stabilities were determined by 2D NMR spectroscopy and tandem mass spectrometry.A heteropseudo[3]rotaxane with rotaxane-like behaviour was isolated chromatographically,displaying electrochemically“frustrated”properties.A robust synthetic procedure was developed allowing the synthesis of four new hetero[3]rotaxanes incorporating specific sequences of functional *** pseudoisomeric rotaxanes which have the naphthalene diimide subunit at two different positions show distinct electrochemical *** calculations suggest that this differences could arise from a folding of the structure,in which the redox-active moieties stack with a stopper *** study presents a blueprint for the construction of hetero[3]rotaxanes with sequential control of the functional units along the track of the axle and paves the way to extend the functionality of mechanically interlocked molecules.

关键词： properties redox Sequence

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Enhancements of SDR-Based FPGA System for v2X-vLC Communications

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Computers, Materials & Continua 2021年第9期68卷 3629-3652页

作者： lukas Danys Radek Martinek Rene Jaros Jan Baros Petr Simonik vaclav Snasel Department of Cybernetics and Biomedical Engineering Faculty of Electrical Engineering and Computer ScienceVSB–Technical University of OstravaOstrava-Poruba70800Czechia Department of Electronics Faculty of Electrical Engineering and Computer ScienceVSB–Technical University of OstravaOstrava-Poruba70800Czechia Department of Computer Science Faculty of Electrical Engineering and Computer ScienceVSB–Technical University of OstravaOstrava-Poruba70800Czechia

This pilot study focuses on a real measurements and enhancements of a software defined radio-based system for vehicle-to everything visible light communication(SDR-v2X-vLC).The presented system is based on a novel adaptive optimization of the feed-forward software defined equalization(FFSDE)methods of the least mean squares(LMS),normalized LMS(NLMS)and QR decomposition-based recursive least squares(QR-RLS)*** parameters of adaptive equalizations are adjusted in real-time to reach the best possible *** were carried out on a conventional LED Octavia III taillight drafted directly from production line and universal software radio peripherals(USRP)from National *** transmitting/receiving elements used multistate quadrature amplitude modulation(M-QAM)implemented in LabvIEW programming *** results were verified based on bit error ratio(BER),error vector magnitude(EvM)and modulation error ratio(MER).Experimental results of the pilot study unambiguously confirmed the effectiveness of the proposed solution(longer effective communication range,higher immunity to interference,deployment of higher state QAM modulation formats,higher transmission speeds etc.),as the adaptive equalization significantly improved BER,MER and EvM *** best results were achieved using the QR-RLS *** results measured on deployed QR-RLS algorithm had significantly better Eb/N0(improved by approx.20 dB)and BER values(difference by up to two orders of magnitude).

关键词： 5G feed-forward software defined equalization multistate quadrature amplitude modulation software defined radio visible light communication

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