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Assessing stress conditions and impact velocities in fluidized bed opposed jet mills

Particuology 2020年第6期18卷 12-22页

作者： Alexander Strobel Benedikt Koninger Stefan Romeis Florian Schott Karl-Ernst Wirth wolfgang Peukert Institute of Particle Technology(LFG) Friedrich-Alexander-Universitat Erlangen-NiirnbergCauerstrae 491058 ErlangenGermany

Fluidized bed opposed jet mills are capable of meeting the continuously growing dema nd for contamination-free fine *** this type of jet mill,the solid material is entrained and accelerated by expanding gas jets that are focused onto a focal point in side a fluidized *** resulting particle collisions induce *** process is affected by the relative particle velocities and the number of particle-particle ***,both quantities are ***,to date,neither relative particle velocities nor collision frequencies in such units have been *** present work introduces an innovative method to assess the stressing conditions in jet mills *** this end,mixtures of glass and ductile metal microspheres were used,with the latter employed in small ***-particle collisions between the aluminum and glass spheres lead to the formation of dents on the *** size and number of these dents are associated with the individual collision velocities and overall collision *** correlation between dent size and collision velocity was obtained from finite element calculations based on empirical *** proposed approach was validated using particle image velocimetry during secondary gas injection into a fluidized bed *** this case the effect of the distance between two opposed nozzles was *** a lab-scaled fluidized bed opposed jet mill the effects of gas pressure and hold-up were *** particle velocities were found to be sign ificantly lower tha n the gas velocities,while the nu mber of contacts per particle was determined to be extremely high.

关键词： Fluidized bed opposed jet mill Single particle probes Finite element modeling Stress number distribution Relative velocity distribution

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Koutecky-Levich analysis applied to nanoparticle modified rotating disk electrodes： Electrocatalysis or misinterpretation？

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Nano Research 2014年第1期7卷 71-78页

作者： Justus Masa Christopher Batchelor-McAuley wolfgang Schuhmann Richard G. Compton Department of Chemistry Physical and Theoretical Chemistry Laboratory University of Oxford South Parks Road Oxford OX13QZ UK Analytische Chemie and Center for Electrochemical Sciences-CES Ruhr-Universitat Bochum Universitatsstr 150 D-44780 Bochum Germany

The application of naive Koutecky-Levich analysis to micro- and nano-particle modified rotating disk electrodes of partially covered and non-planar geometry is critically analysed. Assuming strong overlap of the diffusion fields of the particles such that transport to the entire surface is time-independent and one-dimensional, the observed voltammetric response reflects an apparent electrochemical rate o constant koapp, equal to the true rate constant ko describing the redox reaction of interest on the surface of the nanoparticles and the ratio,ψ, of the total electroactive surface area to the geometric area of the rotating disk surface. It is demonstrated that Koutecky-Levich analysis is applicable and yields the expected plots of I-1 versus ω-1 where I is the current and ω is the rotation speed but that the values of the electrochemical rate constants inferred are thereof koapp, not ko. Thus, for ψ 〉 1 apparent electrocatalysis might be naively but wrongly inferred whereas for ψ 〈 1 the deduced electrochemical rate constant will be less than ko. Moreover, the effect of ψ on the observed rotating disk electrode voltammograms is significant, signalling the need for care in the overly simplistic application of Koutecky-Levich analysis to modified rotating electrodes, as is commonly applied for example in the analysis of possible oxygen reduction catalysts.

关键词： rotating disk electrodes nanoparticles electrocatalysis electrode kinetics electro-reduction ofoxygen Koutecky-Levich analysis

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Effects of Saccharomyces cerevisiae or boulardii yeasts on acute stress induced intestinal dysmotility

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World Journal of Gastroenterology 2016年第48期22卷 10532-10544页

作者： Christine West Andrew M Stanisz Annette Wong wolfgang A Kunze McMaster Brain-Body Institute St. Joseph’s Healthcare Department of Biology McM aster University Department of Psychiatry and Behavioural Neurosciences Mc Master University

AIM To investigate the capacity of Saccharomyces cerevisiae(S. cerevisiae) and Saccharomyces boulardii(S. boulardii) yeasts to reverse or to treat acute stress-related intestinal *** Adult Swiss Webster mice were stressed for 1 h in a wire-mesh restraint to induce symptoms of intestinal dysmotility and were subsequently killed by cervical dislocation. Jejunal and colon tissue were excised and placed within a tissue perfusion bath in which S. cerevisiae, S. boulardii, or their supernatants were administered into the lumen. Video recordings of contractility and gut diameter changes were converted to spatiotemporal maps and the velocity, frequency, and amplitude of propagating contractile clusters(PCC) were measured. Motility pre- and post-treatment was compared between stressed animals and unstressed controls. RESULTS S. boulardii and S. cerevisiae helped to mediate the effects of stress on the small and large intestine. Restraint stress reduced jejunal transit velocity(mm/s)from 2.635 ± 0.316 to 1.644 ± 0.238, P < 0.001 and jejunal transit frequency(Hz) from 0.032 ± 0.008 to 0.016 ± 0.005, P < 0.001. Restraint stress increased colonic transit velocity(mm/s) from 0.864 ± 0.183 to 1.432 ± 0.329, P < 0.001 and frequency to a lesser degree. Luminal application of S. boulardii helped to restore jejunal and colonic velocity towards the unstressed controls; 1.833 ± 0.688 to 2.627 ± 0.664, P < 0.001 and 1.516 ± 0.263 to 1.036 ± 0.21, P < 0.001, respectively. S. cerevisiae also had therapeutic effects on the stressed gut, but was most apparent in the jejunum. S. cerevisiae increased PCC velocity in the stressed jejunum from 1.763 ± 0.397 to 2.017 ± 0.48, P = 0.0031 and PCC frequency from 0.016 ± 0.009 to 0.027 ± 0.007, P < 0.001. S. cerevisiae decreased colon PCC velocity from 1.647 ± 0.187 to 1.038 ± 0.222, P < 0.001. Addition of S. boulardii or S. cerevisiae supernatants also helped to restore motility to unstressed values in similar capacity. CONCLUSION The

关键词： Intestine Saccharomyces cerevisiae Saccharomyces boulardii Restraint stress Motility

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Formation of transgressive anorthosite seams in the Bushveld Complex via tectonically induced mobilisation of plagioclase-rich crystal mushes

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Geoscience Frontiers 2016年第6期7卷 875-889页

作者： wolfgang D.Maier Bartosz T.Karykowski Sheng-Hong Yang School of Earth and Ocean Sciences Cardiff UniversityUK Oulu Mining School University of OuluFinland

The formation of anorthosites in layered intrusions has remained one of petrology＇s most enduring enigmas. We have studied a sequence of layered chromitite, pyroxenite, norite and anorthosite overlying the UG2 chromitite in the Upper Critical Zone of the eastern Bushveld Complex at the Smokey Hills platinum mine. Layers show very strong medium to large scale lateral continuity, but abundant small scale irregularities and transgressive relationships. Particularly notable are irregular masses and seams of anorthosite that have intrusive relationships to their host rocks. An anorthosite layer locally transgresses several 10 s of metres into its footwall, forming what is referred to as a ＂pothole＂ in the Bushveld Complex. It is proposed that the anorthosites formed from plagioclase-rich crystal mushes that originally accumulated at or near the top of the cumulate pile. The slurries were mobilised during tectonism induced by chamber subsidence, a model that bears some similarity to that generally proposed for oceanic mass flows. The anorthosite slurries locally collapsed into pull-apart structures and injected their host rocks. The final step was down-dip drainage of Fe-rich intercumulus liquid, leaving behind anorthosite adcumulates.

关键词： Anorthosite Layered intrusion Bushveld Complex South Africa Chromitite

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Effects of newly devised plasma lice comb on human hair

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Plasma Science and Technology 2019年第12期21卷 78-84页

作者： Lars TEN BOSCH Andreas HUBER Philipp SAUERBIER Robert KOHLER Georg AVRAMIDIS wolfgang VIOL University of Applied Sciences and Arts HAWK Faculty NVon-Ossietzky-Strasse 99/10037085 GottingenGermany Neaspec GmbH Eglfinger Weg 285540 Munich-HaarGermany Wood Biology and Wood Products Faculty of Forest Sciences and Forest EcologyUniversity of GoettingenBüsgenweg 437077 GottingenGermany

A plasma device was developed showing high potential for a pesticide-free treatment of pediculosis. As a first safety assessment of the device was presented earlier, this present paper focuses on the damage introduced to human hair during a plasma treatment for pediculosis control. Therefore, human hairs were treated repeatedly to assess the possible occurring damage developing with increasing treatment durations. To analyse the inflicted changes on human hair examinations using x-ray photoelectron spectroscopy(XPS/ESCA), scanning nearfield optical microscopy(SNOM) and scanning electron microscopy were conducted, to compare the modifications of surface chemistry and mechanical alterations. The investigations revealed a mild impact on the surface chemistry(XPS/SNOM), while more distinct morphological changes on the hair surface could be observed. The authors conclude that an effect of the plasma comb device on the hair during a real-life treatment is negligible, due to the very short contact times during a standard combing procedure for pediculosis control.

关键词： atmospheric pressure plasma dielectric barrier discharge pediculosis SEM SNOM ESCA XPS hair smoothing plasma based pest management

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Corrosion Protection of AM50 Magnesium Alloy by Nafion/DMSO Organic Coatings

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Journal of Wuhan University of Technology(Materials Science) 2008年第2期23卷 204-206页

作者： SONG Renguo ZHENG Xiaohua BAI Shuju BLAWERT Carsten DIETZEL wolfgang The MOE Key Laboratory of Mechanical Manufacture and Automation Zhejiang University of Technology Hangzhou 310014 China Tieling Base Property Company of NEPPC Tieling 112001 China Institute of Materials Research GKSS-Forschungszentrum Geesthacht GmbH Geesthacht D-21502 Germany

The effectiveness of the corrosion protection of Nafion/Dimethysulfoxid （DMSO） organic coatings for AM50 magnesium alloy prepared by simple immersion and heat treatment was investigated. Its corrosion resistance and morphologies of the Nafion/DMSO organic coatings were studied by electrochemical corrosion testing and optical microscopy. The results show that Nafion/DMSO organic coatings can improve the corrosion resistance of AM50 magnesium alloy effectively. Also, the corrosion resistance increases with the surface density of the organic coatings.

关键词： corrosion protection magnesium alloy organic coatings

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Electrochemical drag effect on grain boundary motion in ionic ceramics

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npj Computational Materials 2020年第1期6卷 305-311页

作者： K.S.N.Vikrant wolfgang Rheinheimer R.Edwin García School of Materials Engineering Purdue UniversityWest LafayetteIN 47907USA

The effects of drag imposed by extrinsic ionic species and point defects on the grain boundary motion of ionic polycrystalline ceramics were quantified for the generality of electrical,chemical,or structural driving *** the absence of,or for small driving forces,the extended electrochemical grain boundary remains pinned and symmetrically distributed about the structural *** the grain boundary begins to move,charged defects accumulate unsymmetrically about the structural grain boundary *** the critical driving force for motion,grain boundaries progressively shed individual ionic species,from heavier to lighter,until they display no interfacial electrostatic charge and zero Schottky *** p-n junction moving grain boundaries that induce a finite electrostatic potential difference across entire grains are identified for high velocity *** developed theory is demonstrated for Fe-doped SrTiO_(3).The increase in average Fe concentration and grain boundary crystallographic misorientation enhances grain boundary core segregation and results in thick space charge layers,which leads to a stronger drag force that reduces the velocity of the *** developed theory sets the stage to assess the effects of externally applied fields such as temperature,electromagnetic fields,and chemical stimuli to control the grain growth for developing textured,oriented microstructures desirable for a wide range of applications.

关键词： grain boundary ceramics

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Surface Activation of Plane and Curved Automotive Polymer Surfaces by Using a Fittable Multi-Pin DBD Plasma Source

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Plasma Science and Technology 2014年第6期16卷 593-597页

作者： Jrn HEINE Roland DAMM Christoph GERHARD Stephan WIENEKE wolfgang VIL University of Applied Sciences and Arts Laboratory of Laser and Plasma TechnologyVon-Ossietzky-Stra?e 99 37085 Gttingen Germany Fraunhofer Institute for Surface Engineering and Thin Films Application Center for Plasma and Photonic Von-Ossietzky-Stra?e 99 37085 Gttingen Germany

In this work, surface activation of automotive polymers using atmospheric pressure plasmas was investigated. The aim was to increase the polar fraction of the surface energy of both plane and convex polymer devices with a radius in the range of 30 mm. For this purpose, a fittable low temperature atmospheric pressure plasma source based on capacitively coupled multi-pin electrodes was set up and applied. Each single electrode generates a treatment spot of approximately 2 cm2 with a tunable power density of up to 1.4 W/cm2. The surface energy was evaluated by contact angle measurements. After treatment at a low energy density of 1.01 J/cm2, the polar fraction of the surface energy of the investigated polymers was increased by a factor of 3.3 to 132, depending on the polymer materials. It was shown that by applying the presented fittable plasma source, this effect is independent of the surface radius of the polymer sample.

关键词： surface activation atmospheric pressure plasma adhesion lacquering surfaceenergy

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How can neuromorphic hardware attain brain-like functional capabilities?

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National Science Review 2024年第5期11卷 11-13页

作者： wolfgang Maass Computer Science and Biomedical Engineering Graz University of Technology

Research on neuromorphic computing is driven by the vision that we can emulate brain-like computing capability, learning capability, and energy-efficiency in novel hardware. Unfortunately, this vision has so far been pursued in a half-hearted manner. Most current neuromorphic hardware (NMHW) employs brain-like spiking neurons instead of standard artificial neurons.

关键词： capabilities attain brain-like functional hardware neuromorphic

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Solving the inverse grating problem by white light interference Fourier scatterometry

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Light(Science & Applications) 2012年第1期1卷 17-23页

作者： Valeriano Ferreras Paz Sandy Peterhansel Karsten Frenner wolfgang Osten Institute of Applied Optics Stuttgart University70569 StuttgartGermany SCoPE—Stuttgart Research Center of Photonic Engineering Stuttgart UniversityStuttgartGermany

Scatterometry is a well-established,fast and precise optical metrology method used for the characterization of sub-lambda periodic *** Fourier scatterometry method,by analyzing the Fourier plane,makes it possible to collect the angle-resolved diffraction spectrum without any mechanical *** improve the depth sensitivity of this method,we combine it with white light *** show the exemplary application of the method on a silicon line *** characterize the sub-lambda features of the grating structures,we apply a model-based reconstruction approach by comparing simulated and measured *** simulations are based on the rigorous coupled-wave analysis method.

关键词： Fourier scatterometry inverse problem optical sub-lambda metrology RCWA white light interference

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