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Strong shape-dependence of Morin transition in α-Fe2O3 single-crystalline nanostructures

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Nano Research 2015年第6期8卷 1906-1916页

作者： JunWang victor aguilar Le Li Fa-gen Li Wen-zhong Wang Guo-meng Zhao Department of Physics Faculty of Science Ningbo University Ningbo China Department of Physics and Astronomy California State University Los Angeles CA 90032 USA School of Science Minzu University of China Beijing 100081 China

Single-crystalline hematite （α-Fe2O3） nanorings （short nanotubes） and nanotubes were synthesized by a hydrothermal method. High-resolution transmission electron microscopy and selected-area electron diffraction confirm that the axial directions of both the nanorings and nanotubes are parallel to the crystalline c-axis. Intriguingly, the Morin transition occurs at about 210 K in the short nanotubes with a mean tube length of about 115 nm and a mean outer diameter of about 169 nm. However, it does not occur in the nanotubes with a mean tube length of about 317 nm and a mean outer diameter of about 148 nm. Detailed analysis of magnetization data, X-ray diffraction patterns, and room-temperature M6ssbauer spectra demonstrates that this very strong shape-dependence of Morin transition is intrinsic to hematite. We explain this intriguing shape- dependence quantitatively, in terms of the opposite signs of the surface mag- netic anisotropy constants of the surface planes parallel and perpendicular to the c-axis.

关键词： hematite nanostructures Morin transition shape-dependence surface magneticanisotropy

Mass Spectrometric Analyses Reveal a Central Role for Ubiquitylation in Remodeling the Arabidopsis Proteome during Photomorphogenesis

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Molecular Plant 2017年第6期10卷 846-865页

作者： victor aguilar-Hernandez Do-Young Kim Robert J. Stankey Mark Scalf Lloyd M. Smith Richard D. Vierstra Department of Biology Washington University in St. Louis Campus Box 1137 One Brookings Drive St. Louis MO 63130 USA Department of Genetics 425-G Henry Mall Department of Chemistry 1101 University Avenue University of Wisconsin-Madison Madison WI 53706 USA Advanced Bio Convergence Center Pohang Technopark Gyeong-Buk South Korea 37668

The switch from skotomorphogenesis to photomorphogenesis is a key developmental transition in the life of seed plants. While much of the underpinning proteome remodeling is driven by light-induced changes in gene expression, the proteolytic removal of specific proteins by the ubiquitin-26S proteasome system is also likely paramount. Through mass spectrometric analysis of ubiquitylated proteins affinity-purified from etiolated Arabidopsis seedlings before and after red-light irradiation, we identified a number of influential proteins whose ubiquitylation status is modified during this switch. We observed a substantial enrichment for proteins involved in auxin, abscisic acid, ethylene, and brassinosteroid signaling, peroxisome function, disease resistance, protein phosphorylation and light perception, including the phytochrome （Phy） A and phototropin photoreceptors. Soon after red-light treatment, PhyA becomes the dominant ubiquitylated species, with ubiquitin attachment sites mapped to six lysines. A PhyA mutant protected from ubiquitin addition at these sites is substantially more stable in planta upon photoconversion to Pfr and is hyperactive in driving photomorphogenesis. However, light still stimulates ubiquitylation and degradation of this mutant, implying that other attachment sites and/or proteolytic pathways exist. Collectively, we expand the catalog of ubiquitylation targets in Arabidopsis and show that this post- translational modification is central to the rewiring of plants for photoautotrophic growth.

关键词： Arabidopsis ubiquitin mass spectrometry photomorphogenesis phytochrome degradation

Heating of nanoparticles and their environment by laser radiation and applications

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Nanotechnology and Precision Engineering 2024年第1期7卷 78-115页

作者： victor K.Pustovalov Belarusian National Technical University Pr.Independency65Minsk 220013Belarus

This review considers the fundamental dynamic processes involved in the laser heating of metal nanoparticles and their subsequent *** particular interest are the absorption of laser energy by nanoparticles,the heating of a single nanoparticle or an ensemble thereof,and the dissipation of the energy of nanoparticles due to heat exchange with the *** goal is to consider the dependences and values of the temperatures of the nanoparticles and the environment,their time scales,and other parameters that describe these *** results and analytical studies on the heating of single metal nanoparticles by laser pulses are discussed,including the laser thresholds for initiating subsequent photothermal processes,how temperature inﬂuences the optical properties,and the heating of gold nanoparticles by laser *** studies of the heating of an ensemble of nanoparticles and the results of an analytical study of the heating of an ensemble of nanoparticles and the environment by laser radiation are *** methods for nanoparticles under laser heating are considered,including changes in the refractive indices of metals and spectral thermometry of optical scattering of nanoparticles,Raman spectroscopy,the thermal distortion of the refractive index of an environment heated by a nanoparticle,and thermochemical phase transitions in lipid bilayers surrounding a heated *** the sequence of events after radiation absorption and their time scales underlies many applications of *** applicationﬁelds for the laser heating of nanoparticles are reviewed,including thermochemical reactions and selective nanophotothermolysis initiated in the environment by laser-heated nanoparticles,thermal radiation emission by nanoparticles and laser-induced incandescence,electron and ion emission of heated nanoparticles,and optothermal chemical *** of the laser heating of nanoparticles in la

关键词： Nanoparticles Laser Heating Modeling Nanothermometry Applications

Seamless morphing trailing edge flaps for UAS-S45 using high-fidelity aerodynamic optimization

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Chinese Journal of Aeronautics 2024年第2期37卷 12-29页

作者： Mir Hossein NEGAHBAN Musavir BASHIR victor TRAISNEL Ruxandra Mihaela BOTEZ LARCASE Laboratory of Applied Research in Active Controls Avionics and AeroservoelasticityEcole de Technologie SuperieureUniversite du QuebecMontreal H3C1K3Canada

The seamless trailing edge morphing flap is investigated using a high-fidelity steady-state aerodynamic shape optimization to determine its optimum configuration for different flight conditions,including climb,cruise,and gliding descent.A comparative study is also conducted between a wing equipped with morphing flap and a wing with conventional hinged *** optimization is performed by specifying a certain objective function and the flight performance goal for each flight *** the climb rate,extending the flight range and endurance in cruise,and decreasing the descend rate,are the flight performance goals covered in this *** optimum configurations were found for the morphing wing by determining the optimum morphing flap deflection for each flight condition,based on its objective function,each of which performed better than that of the baseline *** was shown that by using optimum configuration for the morphing wing in climb condition,the required power could be reduced by up to 3.8%and climb rate increases by 6.13%.The comparative study also revealed that the morphing wing enhances aerodynamic efficiency by up to 17.8%and extends the laminar ***,the optimum configuration for the gliding descent brought about a 43%reduction in the descent rate.

关键词： Seamless morphing trailing edge flap Aerodynamic optimization Gradient-based optimiza-tion Climb flight condition Gliding descent Flight range Endurance

Dynamics of Low-Viscosity Liquids Interface in an Unevenly Rotating Vertical Layer

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Fluid Dynamics & Materials Processing 2024年第4期20卷 693-703页

作者： victor Kozlov Vladimir Saidakov Nikolai Kozlov Laboratory of Vibrational Hydromechanics Perm State Humanitarian Pedagogical UniversityPerm614990Russia Institut de Mécanique des Fluides de Toulouse Toulouse INPToulouse31400France

The behavior of two immiscible low-viscosity liquids differing in density and viscosity in a vertical flat layer undergoing modulated rotation is experimentally *** layer has a circular axisymmetric *** the absence of modulation of the rotation speed,the interphase boundary has the shape of a short axisymmetric cylinder.A new effect has been discovered,under the influence of rotation speed modulation,the interface takes on a new dynamic equilibrium state.A more viscous liquid covers the end boundaries of the layer in the form of thin films,which have the shape of round spots of almost constant radius;with increasing amplitude of the velocity modulation,the wetting boundary *** is found that upon reaching the critical amplitude of oscillations,the film of a viscous liquid loses stability,and the outer edge of the wetting spot collapses and takes on a feathery *** is shown that this threshold is caused by the development of the Kelvin-Helmholtz oscillatory instability of the *** spreading radius of a spot of light viscous liquid and its stability are studied depending on the rotation rate,amplitude,and frequency of rotation speed *** discovered averaged effects are determined by different oscillatory interaction of fluids with the end-walls of the cell,due to different *** effect of films forming can find application in technological processes to intensify mass transfer at interphase boundaries.

关键词： Rotation oscillations immiscible fluids contact line interface film dynamic equilibrium Nomenclature frot

Using deep neural networks coupled with principal component analysis for ore production forecasting at open-pit mines

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第3期16卷 727-740页

作者： Chengkai Fan Na Zhang Bei Jiang Wei victor Liu Department of Civil and Environmental Engineering University of AlbertaEdmontonAlbertaT6G 2E3Canada Department of Mathematical and Statistical Sciences University of AlbertaEdmontonAlbertaT6G 2G1Canada

Ore production is usually affected by multiple influencing inputs at open-pit ***,the complex nonlinear relationships between these inputs and ore production remain *** becomes even more challenging when training data(*** haulage information and weather conditions)are *** machine learning(ML)algorithms,deep neural network(DNN)is a superior method for processing nonlinear and massive data by adjusting the amount of neurons and hidden *** study adopted DNN to forecast ore production using truck haulage information and weather conditions at open-pit mines as training *** the prediction models were built,principal component analysis(PCA)was employed to reduce the data dimensionality and eliminate the multicollinearity among highly correlated input *** verify the superiority of DNN,three ANNs containing only one hidden layer and six traditional ML models were established as benchmark *** DNN model with multiple hidden layers performed better than the ANN models with a single hidden *** DNN model outperformed the extensively applied benchmark models in predicting ore *** can provide engineers and researchers with an accurate method to forecast ore production,which helps make sound budgetary decisions and mine planning at open-pit mines.

关键词： Oil sands production Open-pit mining Deep learning Principal component analysis(PCA) Artificial neural network Mining engineering

Efficient cold atom source from a single-layer atom chip

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Chinese Optics Letters 2024年第6期22卷 103-108页

作者： Petr Skakunenko Darya Bykova Anton Afanasiev Alexey Kalmykov Roman Kirtaev victor Balykin Institute of Spectroscopy Russian Academy of Sciences Moscow 108840Russia Moscow Institute of Physics and Technology Moscow 141700Russia Skolkovo Institute of Science and Technology Moscow 121205Russia National Research University Higher School of Economics Moscow 101000Russia Present affiliation:Emerging Technologies Research Center XPANCEODubaiUnited Arab Emirates

We developed a new single-layer atom chip with an additional U-shaped current-carrying *** new U-shaped microwire creates optimized magnetic field distribution,which increases the trapping volume of a magneto-optical trap(MOT) near the *** approach allows one to localize more atoms,while a setup remains relatively simple (single-layer approach) and consumes low current (up to 10 A). The total number of trapped^(87)Rb atoms in our setup is 5×10^(7).

关键词： atom chip cold atoms laser cooling magneto-optical trap U-MOT

Formation of diffuse and spark discharges between two needle electrodes with the scattering of particles

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Plasma Science and Technology 2024年第9期26卷 32-39页

作者： victor F TARASENKO Dmitry V BELOPLOTOV Alexei N PANCHENKO Dmitry A SOROKIN Institute of High Current Electronics Siberian BranchRussian Academy of SciencesTomsk 634055Russia National Research Tomsk State University Tomsk 634050Russia

The development of a nanosecond discharge in a pin-to-pin gap filled with air at atmospheric pressure has been studied with high temporal and spatial resolutions from a breakdown start to the spark *** and negative nanosecond voltage pulses with an amplitude of tens of kilovolts were ***-resolved images of the discharge development were taken with a fourchannel Intensified Charge Coupled Device(ICCD)*** minimum delay between the camera channels could be as short as≈0.1 *** made it possible to study the gap breakdown process with subnanosecond *** was observed that a wide-diameter streamer develops from the high-voltage pointed *** ionization processes near the grounded pin electrode started when the streamer crossed half of the *** bridging the gap by the streamer,a diffuse discharge was *** development of spark leaders from bright spots on the surface of the pointed electrodes was observed at the next *** was found that the rate of development of the spark leader is an order of magnitude lower than that of the wide-diameter *** thin luminous tracks were observed against the background of a discharge plasma *** has been established that the tracks are adjacent to brightly glowing spots on the electrodes and are associated with the flight of small particles.

关键词： needle electrodes short voltage pulses atmospheric air streamer breakdown diffuse and spark discharges scattering metal particles

New approach for particle size and shape analysis of iron-based oxygen carriers at multiple oxidation states

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Particuology 2024年第7期90卷 493-503页

作者： victor Purnomo Marcelo Dal Belo Takehara Robin Faust Lidiya Abdisa Ejjeta Henrik Leion Division of Energy and Materials Department of Chemistry and Chemical EngineeringChalmers University of TechnologyGöteborg 41258Sweden Division of Energy Science Department of Engineering Sciences and MathematicsLuleåUniversity of TechnologyLuleå97187Sweden

One of the crucial issues in the chemical looping technology lies in its bed material:the oxygen *** size analysis of an oxygen carrier is important since in a fluidized bed the material can only work well within a specific size *** the favorable size ranges for oxygen carrier materials have already been reported,none of the published studies has analyzed the particle size and shape of oxygen carriers in ***,the effect of oxygen carriers'oxidation degree on such properties has not been considered *** study aimed to report the particle size and shape analysis of five iron-based oxygen carriers,one natural ore,one synthetic material,and three residue products,at different oxidation degrees using dynamic image analysis(DIA).The oxygen carriers were prepared at different mass conversion degrees in a fluidized bed batch *** size distribution,sphericity,and aspect ratio of the oxygen carrier particles were examined experimentally using a Camsizer *** results show that the DIA method was successfully able to analyze the particle size and shape of our oxygen carriers with satisfying accuracy for *** oxidation state of the investigated materials seems to only affect the particle size and shape of oxygen carriers to a minor ***,exposures to redox cycles in a fluidized bed reactor may alter the particle size and shape of most oxygen carriers.

关键词： Oxygen carrier Size and shape analysis Dynamic image analysis Oxidation state Fluidized bed Chemical looping