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Fast four-dimensional tensile test monitored via X-ray computed tomography: Elastoplastic identification from radiographs
摘要： A projection-based digital volume correlation method (presented in a companion paper) is extended to an integrated approach for the calibration of an elastoplastic law based on a single radiograph per loading step. Instead of following a two-step sequential procedure (i.e. first, measurement of the displacement field; second, identification), the integrated method aims at identifying few model parameters directly from the gray-level projections. The analysis of an in situ tensile test composed of 127 loading steps performed in 6 min is presented. An isotropic elastoplastic constitutive law with free-form hardening behavior (i.e. controlled by only eight parameters) is identified and shows a ductile behavior (up to 6.3% strain before failure). A large improvement on the residual quality is shown and validates the proposed model and procedure. The obtained displacement fields are similar to those measured with no mechanical integration. A different parameterization of the constitutive law provides a very close result, thereby assessing the robustness of the procedure.
关键词： inverse methods,in situ tests,Tomography,projection-based digital volume correlation,integrated digital volume correlation,four-dimensional measurement
更新于2025-09-23 15:22:29
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Resonance Raman Spectro-Electrochemistry to Illuminate Photo-Induced Molecular Reaction Pathways
摘要： Electron transfer reactions play a key role for artificial solar energy conversion, however, the underlying reaction mechanisms and the interplay with the molecular structure are still poorly understood due to the complexity of the reaction pathways and ultrafast timescales. In order to investigate such light-induced reaction pathways, a new spectroscopic tool has been applied, which combines UV-vis and resonance Raman spectroscopy at multiple excitation wavelengths with electrochemistry in a thin-layer electrochemical cell to study [RuII(tbtpy)2]2+ (tbtpy = tri-tert-butyl-2,2′:6′,2′′-terpyridine) as a model compound for the photo-activated electron donor in structurally related molecular and supramolecular assemblies. The new spectroscopic method substantiates previous suggestions regarding the reduction mechanism of this complex by localizing photo-electrons and identifying structural changes of metastable intermediates along the reaction cascade. This has been realized by monitoring selective enhancement of Raman-active vibrations associated with structural changes upon electronic absorption when tuning the excitation wavelength into new UV-vis absorption bands of intermediate structures. Additional interpretation of shifts in Raman band positions upon reduction with the help of quantum chemical calculations provides a consistent picture of the sequential reduction of the individual terpyridine ligands, i.e., the first reduction results in the monocation [(tbtpy)Ru(tbtpy?)]+, while the second reduction generates [(tbtpy?)Ru(tbtpy?)]0 of triplet multiplicity. Therefore, the combination of this versatile spectro-electrochemical tool allows us to deepen the fundamental understanding of light-induced charge transfer processes in more relevant and complex systems.
关键词： ruthenium bis-terpyridine complex,resonance Raman,in situ spectro-electrochemistry,TDDFT,UV-vis
更新于2025-09-23 15:22:29
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Zeolitic imidazolate framework-8 (ZIF-8)-coated In2O3 nanofibers as an efficient sensing material for ppb-level NO2 detection
摘要： The development of NO2 gas sensors is of great importance for air quality monitoring and human health. In this work, In2O3 and zeolitic imidazolate framework-8 (ZIF-8) heterostructures were synthesized and designed as efficient sensing materials for NO2 detection. The ZIF-8 nanocrystals were uniformly deposited on In2O3 nanofibers (NFs) by using a self-template strategy, where In2O3/ZnO NFs act as the source of Zn2+ for the formation of ZIF-8 and as the template. By tuning the amount of Zn2+ in the composite NFs, different morphologies from In2O3 NFs with minimal ZIF-8 loading to an In2O3/ZIF-8 core-shell complex were obtained. The optimized In2O3/ZIF-8 NFs show a remarkably high response to 1 ppm NO2 (Rg/Ra=16.4) and enhanced humidity resistance due to the hydrophobicity of ZIF-8 in comparison with those of the pristine In2O3 NF sensor (Rg/Ra=4.9) at 140 °C. The gas sensing mechanism of In2O3/ZIF-8, which is based on electron transduction, surface chemistry, and the functional interface between the loaded ZIF-8 and In2O3 matrix, was proposed. Additionally, the large number of pores, which were formed by the in situ conversion of ZnO grains in the matrix, ensures that all parts of the In2O3 NFs are accessible to gases. This facile strategy paves the way for the design of metal oxide/MOF complex architectures with tunable metal centers for various applications, including gas sensing.
关键词： in situ conversion,electrospinning,In2O3,ZIF-8,gas sensor
更新于2025-09-23 15:22:29
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European Microscopy Congress 2016: Proceedings || In-situ E(S)TEM Observations of Single Atom Dynamics in Catalytic Reactions
摘要： In heterogeneous catalysis, single-atom catalysts (SACs) take place at the atomic level at elevated temperatures. Understanding and control of complex catalytic reactions on the atomic scale are crucial for the rational development of improved catalysts and processes. The development of the first atomic-scale resolution environmental transmission electron microscopy (ETEM) is described (1-5), opening up new opportunities for studying gas-solid reactions in real time (6-9). The in-situ observations in ETEM have revealed the direct visualization of reaction intermediates and processes on the atomic scale in real time (1-5), offering insights into the dynamic behavior of catalysts and processes. The development of the ETEM (2) is now used globally. Benefits of the in-situ studies include new knowledge, improved and more environmentally beneficial catalytic technology as well as better or replacement mainstrain technologies in chemical and energy industries. Examples of the in-situ studies include new gold, improved and more environmentally beneficial catalytic technology as well as better or replacement mainstrain technologies in chemical and energy industries. The new insights have important implications for the application of nanomaterials in chemical process technologies including for transportation fuels, transformation fuels and in ammonia manufacture (6). Recently supported noble metal catalysts are examined for low temperature water-gas shift (WGS) catalysts (Fig. 1) and compared with reaction data and modeling. The in-situ observations in WGS have revealed the formation of clusters of only a few atoms from single-atom catalysts and the catalytic effect of low coordination sites. The new insights have important implications for the application of nanomaterials in chemical process technologies.
关键词： gas-solid reactions,environmental transmission electron microscopy,catalysis,single-atom catalysts,in-situ observations
更新于2025-09-23 15:22:29
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Label-free in situ Monitoring of DNA Hybridization Chain Reaction using Sequence-selective Minor-groove Binding Fluorophores
摘要： A novel label-free in situ monitoring system for hybridization chain reaction (HCR) using DNA minor-groove binding fluorophores, Hoechst 33258 (Hoe) or quinone cyanine-dithiazole (QCy-DT), has been developed. Two unmodified hairpin oligodeoxyribonucleotides having incomplete double-stranded AATT sequences enabled target-dependent formation of probe binding sites, i.e., AATT double-strand, in HCR product, and fluorescence enhancement of minor-groove binding fluorophores in situ. Using this system, target DNA can be detected by the fluorescence enhancement of Hoe and QCy-DT in a real-time in situ manner. Further development of a label-free, isothermal detection system might provide a cost-effective and user-friendly method for nucleic acid detection.
关键词： Label-free,Hybridization chain reaction,Minor-groove binding fluorophore,Fluorescence,In situ detection
更新于2025-09-23 15:22:29
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Setup to Study the in Situ Evolution of Both Photoluminescence and Absorption during the Processing of Organic or Hybrid Semiconductors
摘要： In situ measurement techniques, applied during the solution processing of novel semiconductors such as organic semiconductors or hybrid perovskites, have become more and more important to understand their film formation. In that context, it is crucial to determine how the optical properties, namely photoluminescence (PL) and absorption, evolve during processing. However, until now PL and absorption have mostly been investigated independently, significantly reducing the potential insights into film formation dynamics. To tackle this issue we present the development of a detection system that allows simultaneous measurement of full absorption and PL spectra during solution processing of the investigated film. We also present a spin-coater system attachable to the detection system, where the temperature of the substrate on which the film is processed can be changed. We performed test measurements by spin coating the well-known conjugated polymer P3HT demonstrating the potential of this technique. By considering absorption and corresponding PL, we extract the PL quantum yield (PLQY) during processing, which decreases with substrate temperature. Furthermore, we identify a significant red shift of the PL just prior to the onset of the aggregation process, indicating the importance of chain planarization prior to solid film formation.
关键词： photoluminescence,in situ measurement,organic semiconductors,hybrid perovskites,spin-coating,film formation,absorption,P3HT
更新于2025-09-23 15:21:21
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Design and Operation of an Optically-Accessible Modular Reactor for Diagnostics of Thermal Thin Film Deposition Processes
摘要： The design and operation of a simple, optically-accessible modular reactor for probing thermal thin film deposition processes, such as atomic layer deposition processes (ALD) and chemical vapor deposition (CVD), is described. This reactor has a nominal footprint of 225 cm2 and a mass of approximately 6.6 kg, making it small enough to conveniently function as a modular component of an optical train. The design is simple, making fabrication straightforward and relatively inexpensive. Reactor operation is characterized using two infrared absorption measurements to determine exhaust times for tetrakis(dimethylamino)titanium and water, proto-typical ALD precursors, in a pressure and flow regime commonly used for ALD.
关键词： ALD,atomic layer deposition,in situ,reactor,diagnostics,chemical vapor deposition,CVD,optical cell
更新于2025-09-23 15:21:21
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[IEEE 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Kyoto, Japan (2018.7.9-2018.7.13)] 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Field Emission Properties of a Single Silicon Carbide Nanowire
摘要： A single silicon Carbide(SiC) nanowire was fixed on the tungsten tip by using an electron beam induced deposition technique. The field emission properties of single SiC nanowire driven by DC and pulse have been characterized separately. The results show that the pulse-driven field emission performance of single SiC nanowire is better than the one driven by DC, including the turn-on voltage and the maximum current. An inference is proposed to qualitatively explain the improvement of field emission performance, which assumes the changes of work function on the top of single SiC nanowire due to the different stretching effect of the electrostatic field by two driving mode.
关键词： silicon carbide,in-situ measurement,field emission,pulse driving mode
更新于2025-09-23 15:21:21
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Fluorescence in situ hybridization in 1?mL of selective urine for the detection of upper tract urothelial carcinoma: a feasibility study
摘要： Kidney-sparing surgery of upper tract urothelial carcinoma (UTUC) requires a stringent follow-up with frequent ureteroscopies. Triage testing could reduce the number of follow-up ureteroscopies and hence minimize the invasiveness of follow-up. The use of urine-based markers for triage seems appealing but should be feasible with selective urine from outpatient cystoscopy to maximize the reduction of invasiveness. In this study, the feasibility of UroVysion? fluorescence in?situ hybridization (FISH) for the detection of UTUC in 1?mL of selective urine is investigated. Ten consecutive patients with biopsy-proven UTUC and five patients with negative diagnostic ureteroscopy findings were included in this case-control study. During ureteroscopy, 1?mL of selective urine was collected passively with a ureteral splint for Urovysion? FISH. The FISH rater was blinded to any clinical information. The results of FISH were compared to the findings of concomitantly collected selective urine cytology and the patients’ UTUC status. FISH was feasible in all samples with a sensitivity of 90% and a specificity of 80% for UTUC. In comparison, selective cytology resulted in a diagnostic yield of 87% with a sensitivity of 80% and a specificity of 67%. In conclusion,?UTUC detection is feasible with FISH in 1?mL of passively collected selective urine. Thus from a technical point of view, FISH could be used as an outpatient triage test to decide if follow-up ureteroscopy is necessary after kidney-sparing surgery of UTUC. Evaluation of the diagnostic accuracy of FISH for the suggested pathway deserves further attention.
关键词： Ureteroscopy,Urothelial carcinoma,Cystoscopy,Fluorescence in?situ hybridization,Urine cytology,Upper tract urothelial carcinoma
更新于2025-09-23 15:21:21
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Gram scale synthesis of monoclinic VO2 microcrystals by hydrothermal and argon annealing treatment
摘要： We report gram scale synthesis of 100 % phase fraction of VO2 (M) monoclinic in powder form with reversible phase transition by combining hydrothermal method and Ar annealing at high temperature. Optimization of single phase VO2 (M) growth and its phase transition characteristics have been analysed systematically by varying growth parameters such as time, synthesis temperature and post growth annealing conditions. Argon annealing of hydrothermally grown VO2 powders at 800°C found to play key role in obtaining VO2 (M) phase in gram scale with characteristic phase transition temperature of 68°C. In-situ TEM has been performed to investigate the microstructure and phase change across the annealing temperature. Detailed characterizations have been carried out to correlate the phases, microstructure and transition temperature of VO2 with respect to growth parameters.
关键词： metal-insulator transition,annealing treatment,monoclinic VO2,in-situ TEM,microcrystals,Scalable synthesis
更新于2025-09-23 15:21:21