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Galvanically induced potentials to enable minimal tribochemical wear of stainless steel lubricated with sodium chloride and ionic liquid aqueous solution

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Friction 2018年第2期6卷 230-242页

作者： tobias AMANN Felix GATTI Natalie OBERLE Andreas KAILER Jürgen RüHE Fraunhofer Institute for Mechanics of Materials IWM Institute for Macromolecular Chemistry University of Freiburg IMTEK-Department of Microsystems Engineering University of Freiburg

The effect of galvanically induced potentials on the friction and wear behavior of a 1 RK91 stainless steel regarding to tribocorrosion was investigated using an oscillating ball-on-disk tribometer equipped with an electrochemical cell. The aim of this investigation is to develop a water-based lubricant. Therefore 1 molar sodium chloride(NaCl) and 1% 1-ethyl-3-methylimidazolium chloride [C_2 mim][Cl] water solutions were used. Tribological performance at two galvanically induced potentials was compared with the non-polarized state: cathodic potential-coupling with pure aluminum- and anodic potential-coupling with pure copper. Frictional and electrochemical response was recorded during the tests. In addition, wear morphology and chemical composition of the steel were analyzed using scanning electron microscopy(SEM) and X-ray photoelectron spectroscopy(XPS), respectively. The galvanically induced cathodic polarization of the stainless steel surface results in electrochemical corrosion protection and the formation of a tribolayer. Cations from the electrolyte(sodium Na^+ and 1-ethyl- 3-methylimidazolium [C_2 mim]^+) interact and adhere on the surface. These chemical interactions lead to considerably reduced wear using 1 NaC l(86%) and 1% 1-ethyl-3-methylimidazolium chloride [C_2 mim][Cl](74%) compared to the nonpolarized system. In addition, mechanical and corrosive part of wear was identified using this electrochemical technique. Therefore this method describes a promising method to develop water-based lubricants for technical applications.

关键词： sliding wear tribochemistry potential controlled friction and wear galvanic coupling ionic liquids tribolayer formation

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Impact of the terrestrial reference frame on the determination of the celestial reference frame

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Geodesy and Geodynamics 2019年第1期10卷 58-71页

作者： Maria Karbon Santiago Belda tobias Nilsson Institute of Geodesy and Geoinformation University of Bonn Image Processing Laboratory (IPL)-Laboratory of Earth Observation (LEO) University of Valencia Lantmateriet

Currently three up-to-date Terrestrial Reference Frames(TRF) are available, the ITRF2014 from IGN, the DTRF2014 from DGFI-TUM, and JTRF2014 from JPL. All use the identical input data of space-geodetic station positions and Earth orientation parameters, but the concept of combining these data is fundamentally different. The IGN approach is based on the combination of technique solutions, while the DGFI is combining the normal equation systems. Both yield in reference epoch coordinates and velocities for a global set of stations. JPL uses a Kalman filter approach, realizing a TRF through weekly time series of geocentric coordinates. As the determination of the CRF is not independent of the TRF and vice versa, the choice of the TRF might impact on the CRF, Within this work we assess this *** find that the estimated Earth orientation parameter(EOP) from DTRF2014 agree best with those from ITRF2014, the EOP resulting from JTRF2014 show besides clear yearly signals also some artifacts linked to certain stations. The estimated source position time series however, agree with each other better than ±1 μas. When fixing EOP and station positions we can see the maximal effect of the TRF on the CRF. Here large systematics in position as well as proper motion arise. In case of ITRF2008 they can be linked to the missing data after 2008. By allowing the EOP and stations to participate in the adjustment,the agreement increases, however, systematics remain.

关键词： Reference frames CRF TRF DTRF2014 JTRF2014 ITRF2014

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Assessing quality of volunteer crowdsourcing contributions:lessons from the Cropland Capture game

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International Journal of Digital Earth 2016年第4期9卷 410-426页

作者： Carl F.Salk tobias Sturn Linda See Steffen Fritz Christoph Perger Ecosystems Services and Management Program International Institute for Applied Systems AnalysisLaxenburgAustria Southern Swedish Forest Research Center Swedish University of Agricultural SciencesAlnarpSweden

Volunteered geographic information(VGI)is the assembly of spatial information based on public *** VGI has proliferated in recent years,assessing the quality of volunteer-contributed data has proven challenging,leading some to question the efficiency of such *** this paper,we compare several quality metrics for individual volunteers’*** data were the product of the‘Cropland Capture’game,in which several thousand volunteers assessed 165,000 images for the presence of cropland over the course of 6 *** compared agreement between volunteer ratings and an image’s majority classification with volunteer self-agreement on repeated images and expert *** also examined the impact of experience and learning on *** self-agreement was nearly always higher than agreement with majority classifications,and much greater than agreement with expert validations although these metrics were all positively *** quality showed a broad trend toward improvement with experience,but the highest accuracies were achieved by a handful of moderately active contributors,not the most active *** results emphasize the importance of a universal set of expert-validated tasks as a gold standard for evaluating VGI quality.

关键词： crowdsourcing volunteered geographic information cropland data quality image classification Geo-Wiki

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UV-LED projection photolithography for high-resolution functional photonic components

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Microsystems & Nanoengineering 2021年第4期7卷 149-159页

作者： Lei Zheng Urs Zywietz tobias Birr Martin Duderstadt Ludger Overrmeyer Bernhard Roth Carsten Reinhardt Hannover Centre for Optical Technologies Leibniz University HannoverHannoverLower Saxony 30167Germany Cluster of Excellence PhoenixD(Photonics Opticsand Engineering-Innovation Across Disciplines)HannoverLower Saxony 30167Germany Laser Zentrum Hannover e.V HannoverLower Saxony 30167Germany Institute of Transport and Automation Technology Leibniz University HannoverGarbsenLower Saxony 30823Germany Bremen University of Applied Science BremenBremen 28199Germany

The advancement of micro-and nanostructuring techniques in optics is driven by the demand for continuous miniaturization and the high geometrical accuracy of photonic devices and integrated ***,UV-LED projection photolithography is demonstrated as a simple and low-cost approach for rapid generation of two-dimensional optical micro-and nanostructures with high resolution and accuracy using standard optics *** developed system enables the projection of structure patterns onto a substrate with 1000-fold *** devices,e.g.,waveguides and microring resonators,on rigid or flexible substrates with varied geometrical complexity and overall structure dimensions from the nanometer to centimeter scale were successfully *** particular,high-resolution gratings with feature sizes down to 150 nm and periods as small as 400 nm were realized for the first time by this *** made of doped laser active materials were fabricated,and their spontaneous emission was *** demonstrated superior performance of the developed approach may find wide applications in photonics,plasmonics,and optical materials science,among others.

关键词： projection resolution optics

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Tuning Ice Nucleation by Mussel-Adhesive Inspired Polyelectrolytes:The Role of Hydrogen Bonding

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CCS Chemistry 2022年第9期4卷 2980-2990页

作者： Jing Chen Yongkang Wang Benjamin Leibauer Takakazu Seki Konrad meister Yuki Nagata Mischa Bonn Department of Chemistry School of ScienceTianjin University of Science&TechnologyTianjin 300457 Max Planck Institute for Polymer Research Mainz 55128 School of Mechanical Engineering Southeast UniversityNanjing 211189 School of Arts&Sciences University of Alaska SoutheastJuneauAlaska 99801

Heterogeneous ice nucleation(HIN)on foreign surfaces plays a crucial role across a wide range of environmental and biological processes,and control of HIN is highly *** surfaces to control HIN poses interesting scientific challenges and holds great potential for technological ***,we combine the ice nucleation tuning capability of polyelectrolytes withmussel-inspired adhesives to obtain robust surface functionalization with HIN control.

关键词： ice nucleation polyelectrolyte catechol sum-frequency generation hydrogen bonding

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Glacier Fluctuations between 1975 and 2008 in the Greater Himalaya Range of Zanskar,Southern Ladakh

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Journal of Mountain Science 2011年第3期8卷 374-389页

作者： Ulrich KAMP Martin BYRNE tobias BOLCH Department of Geography The University of Montana Geographisches Institut Universitt Zürich

Glaciers in the Himalaya are often heavily covered with supraglacial debris,making them difficult to study with remotely-sensed imagery *** methods such as band ratios can be used effectively to map clean-ice glaciers;however,a thicker layer of debris often makes it impossible to distinguish between supraglacial debris and the surrounding ***,a morphometric mapping approach employing an ASTER-derived digital elevation model has been used to map glaciers in the Khumbu Himal and the Tien *** study on glaciers in the Greater Himalaya Range in Zanskar,southern Ladakh,aims (i) to use the morphometric approach to map large debris-covered glaciers;and (ii) to use Landsat and ASTER data and GPS and field measurements to document glacier change over the past four *** work was carried out in the summers of *** clean ice,band ratios from the ASTER dataset were used to distinguish glacial *** debris-covered glaciers,topographic features such as slope were combined with thermal imagery and supervised classifiers to map glacial *** method is promising for large glaciers,although problems occurred in the distal and lateral parts and in the fore field of the glaciers.A multi-temporal analysis of glaciers in Zanskar showed that in general they have receded since at least the mid-to ***,some few glaciers that advanced or oscillated - probably because of specific local environmental conditions - do exist.

关键词： Glacier Mapping Himalaya Ladakh Monitoring Zanskar

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[Y(dbm)_(3)(H_(2)O)]:Synthesis,thermal behavior and spin-coating precursor for Y_(2)O_(3)layer formation

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Journal of Rare Earths 2017年第12期35卷 1248-1254页

作者： Elaheh Pousaneh Andrea Preuβ Khaybar Assim Julian Noll Alexander Jakob tobias Rüffer Heinrich Lang Technische Universitat Chemnitz Faculty of Natural SciencesInstitute of ChemistryInorganic Chemistry

The synthesis,structure and thermal behavior of [Y（dbm）3（H2 O）]（3）（dbm = 1,3-diphenyl-1,3-propandionate） and its use as a spin-coating precursor for Y2 O3 deposition is reported. Complex 3 was prepared by the reaction of [Y（NO3）3·6 H2 O]（1） with 3 equiv of Hdbm（2） in presence of NaOH. The molecular structure of 3 in the solid-state was determined by single X-ray crystal diffraction. Both C1 symmetric crystallographically independent species of 3 possess a YO7 coordination setup with minor deviation from an ideal capped octahedron coordination geometry（∧ enantiomer）. Complex 3 forms a1 D chain, due to intermolecular hydrogen bonds between the coordinated H2 O molecule and the 0 atom of the dbm ligand, respectively. The thermal decomposition behavior of 3 was investigated by thermogravimetric studies in the temperature range of 40-800 ℃ and 40-1300 ℃ under an oxygen and argon atmosphere, respectively. Powder X-ray diffraction（PXRD） measurements of the residues confirmed the formation of Y2 O3. Complex 3 was applied as a spin-coating precursor for yttrium oxide film formation on either Si wafers with a continuous 100 nm thick SiO2 film, or with a native oxide *** as-deposited Y2 O3 layers are smooth, conformal, dense and transparent and are of a thickness of 27 and 30 nm, respectively.

关键词： Yttrium β-Diketonate Yttrium oxide Spin-coating Solid-state structure Vapor pressure

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Dynamics of Submersible Mussel Rafts in Waves and Current

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China Ocean Engineering 2015年第3期29卷 431-444页

作者： WANG Xin-xin M.Robinson SWIFT tobias DEWHURST Igor TSUKROV Barbaros CELIKKOL Carter NEWELL Center for Ocean Engineering and Mechanical Engineering Department University of New Hampshire Laboratory of Fisheries Engineering Fisheries College Ocean University of China Pemaquid Mussel Farms

To investigate the dynamics of submersible mussel rafts, the finite element program Aqua-FETM, developed by the University of New Hampshire（UNH）, was applied to rafts moored at the surface and submerged. The submerged configuration is used to reduce wave forcing and to avoid contact with floating ice during winters in northern waters. Each raft consists of three pontoons connected by a grid framework. Rafts are intended to support densely spaced mussel ropes hung from the framework. When submerged, the pontoons are flooded, and the raft is held vertically by floats attached by lines. The computer models were developed in Aqua-FE？ to simulate the effects of waves and current. They were validated by comparison with wave tank results by use of a 1/10 scale raft physical model. Comparisons showed good agreement for the important heave（vertical） and pitch（rotational） motions, though there was a tendency towards conservative results for wave and current drag. Full-scale simulations of surface and submerged single raft and two rafts connected in tandem were performed. Submerged raft wave response was found to be reduced relative to that at the surface for both the single and two-raft configurations. In particular, the vertical motion of mussel rope connection points was significantly reduced by submergence, resulting in reduced potential for mussel drop-off. For example, the maximum vertical velocities of mussel rope attachment points in the submerged two raft case were 7%-20% of the corresponding velocities when at the surface.

关键词： mussel raft submersible mussel ropes finite element model waves and current storm response

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Versatile multiplexed super-resolution imaging of nanostructures by Quencher-Exchange-PAINT

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Nano Research 2018年第12期11卷 6141-6154页

作者： tobias Lutz Alexander H.Clowsley Ruisheng Lin Stefano Pagliara Lorenzo Di Michele Christian Soeller Living Systems Institute & Biomedical Physics University of ExeterExeter EX44QDUK Cavendish Laboratory University of CambridgeCambridge CB30HEUK

The optical super-resolution technique DNA-PAINT (Point Accumulation Imaging in Nanoscale Topography) provides a flexible way to achieve imaging of nanoscale structures at ∼10-nanometer resolution. In DNA-PAINT, fluorescently labeled DNA “imager” strands bind transiently and with high specificity to complementary target “docking” strands anchored to the structure of interest. The localization of single binding events enables the assembly of a super-resolution image, and this approach effectively circumvents photobleaching. The solution exchange of imager strands is the basis of Exchange-PAINT, which enables multiplexed imaging that avoids chromatic aberrations. Fluid exchange during imaging typically requires specialized chambers or washes, which can disturb the sample. Additionally, diffusional washout of imager strands is slow in thick samples such as biological tissue slices. Here, we introduce Quencher-Exchange-PAINT—a new approach to Exchange-PAINT in regular open-top imaging chambers—which overcomes the comparatively slow imager strand switching via diffusional imager washout. Quencher-Exchange-PAINT uses “quencher” strands, i.e., oligonucleotides that prevent the imager from binding to the targets, to rapidly reduce unwanted single-stranded imager concentrations to negligible levels, decoupled from the absolute imager concentration. The quencher strands contain an effective dye quencher that reduces the fluorescence of quenched imager strands to negligible levels. We characterized Quencher-Exchange-PAINT when applied to synthetic, cellular, and thick tissue samples. Quencher-Exchange-PAINT opens the way for efficient multiplexed imaging of complex nanostructures, e.g., in thick tissues, without the need for washing steps.

关键词： super-resolution microscopy fluorescence imaging DNA nanotechnology DNA-PAINT fluorescence quencher

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Assessment of stricturing Crohn's disease:Current clinicalpractice and future avenues

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World Journal of Gastroenterology 2016年第3期22卷 1008-1016页

作者： Dominik Bettenworth tobias M Nowacki Friederike Cordes Boris Buerke Frank Lenze Department of Medicine B University Hospital of Muenster48149 MuensterGermany Department of Clinical Radiology University Hospital of Muenster48149 MuensterGermany

Crohn's disease(CD) is a chronic remittent idiopathic disease. Although the early phase of the disease is commonly characterized by inflammation-driven symptoms, such as diarrhea, the frequency of fibrostenotic complications in patients with CD increases over the long-term course of the disease. This review presents the current diagnostic options for assessing CD-associated strictures. In addition to the endoscopic evaluation of CD strictures, this review summarizes the currently available imaging modalities, including ultrasound and cross-sectional imaging techniques. In addition to stricture detection, differentiating between the primarily inflammatory strictures and the predominantly fibrotic ones is essential for selecting the appropriate treatment strategy(anti-inflammatory medical treatment vs endoscopical or surgical approaches). Therefore, recent imaging advances, such as contrast-enhanced ultrasound and ultrasound elastography, contribute to the development of noninvasive non-radiating imaging of CD-associated strictures. Finally, novel magnetic resonance imaging techniques, such as diffusion-weighted, motility and magnetization transfer imaging, as well as 18F-FDG PET/CT, molecular imaging approaches and biomarkers, are critically reviewed with regard to their potential role in assessing stricturing CD.

关键词： Crohn's disease Inflammatory bowel disease Intestinal stricture Endoscopy Magnetic resonanceimaging Ultrasound Computed tomography 18F-FDGPET/CT CEUS Elastography

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