Browse
Recent Submissions
Now showing 1 - 3 of 3
- ItemCoherence-encoded synthetic aperture for super-resolution quantitative phase imaging(AIP Publishing, 2022-04-01) Ďuriš, Miroslav; Bouchal, Petr; Rovenská, Katarína; Chmelík, RadimQuantitative phase imaging (QPI) has quickly established its role in identifying rare events and screening in biomedicine or automated image data analysis using artificial intelligence. These and many other applications share the requirement for extensive high-quality datasets, which is challenging to meet because the invariance of the space-bandwidth product (SBP) fundamentally limits the microscope system throughput. Here, we present a method to overcome the SBP limit by achieving QPI super-resolution using a synthetic aperture approach in a holographic microscope with a partially coherent broad source illumination. We exploit intrinsic coherence-gating properties of the partially coherent light combined with the oblique illumination provided by the diffraction on a simple phase grating placed in proximity of the specimen. We sequentially coherence gate the light scattered into each grating's diffraction order, and we use the acquired images to synthesize QPI with significantly increased spatial frequency bandwidth. The resolution of QPI is increased substantially beyond Abbe's diffraction limit while a large field of view of low numerical aperture objectives is kept. This paper presents a thorough theoretical treatment of the coherence-gated imaging process supplemented by a detailed measurement methodology. The capability of the proposed method is demonstrated by imaging a phase resolution target and biological specimens. We envision our work providing an easily implementable super-resolution QPI method particularly suitable for high-throughput biomedical applications.
- ItemMicrostructural changes during deformation of AISI 300 grade austenitic stainless steels: Impact of chemical heterogeneity(Elsevier, 2016-06-24) Man, Jiří; Kuběna, Ivo; Man, Ondřej; Weidner, Anja; Chlup, Zdeněk; Polák, JaroslavThe present work points out the importance of chemical heterogeneity on the destabilization of austenitic structure and the formation of deformation induced martensite (DIM) in AISI 300 grade austenitic stainless steels (ASSs) of different level of austenite stability (316L, 304, 301LN). Color etching reveals that the structure of wrought Cr-Ni type steels is never fully chemically homogeneous. Confrontation of distribution and morphology of DIM formed in the volume of material after static and cyclic straining under well controlled different conditions with the characteristic local variations in chemical composition of diverse wrought semi-product forms (plates, sheets, bars) proved prominent and very important role of chemical banding in the destabilization of originally fully austenitic structure. This fact should be considered especially when interpreting the results of hydrogen embrittlement tensile testing of Cr-Ni ASSs with lowered Ni content. An impact of chemical heterogeneity on microstructural changes during production of UFG structure of 301LN and its cyclic straining is highlighted.
- ItemNon-aqueous template-assisted synthesis of mesoporous nanocrystalline silicon orthophosphate(Royal Society of Chemistry, 2015-01-01) Styskalik, Aleš; Škoda, David; Moravec, Zdeněk; Roupcová, Pavla; Barnes, Craig E.; Pinkas, JiříThe first synthesis of mesoporous nanocrystalline silicon orthophosphate Si5P6O25 is presented. The synthetic procedure is based on the non-hydrolytic sol-gel reaction in the presence of Pluronic P123 template and subsequent calcination in air. The condensation of silicon acetate, Si(OAc)(4), and tris(trimethylsilyl) phosphate, OP(OSiMe3)(3) (TTP), in non-aqueous solvents driven by elimination of trimethylsilyl acetate provides a homogeneous network with a high content of Si-O-P bonds and SiO6 moieties. After burning out the template, mesoporous silicon orthophosphate was obtained with surface areas up to 128 m(2) g(-1) and pore sizes around 20 nm. The nanocrystalline Si5P6O25 phase forms relatively easily (500 degrees C, 4 h) in comparison with other synthetic routes. All samples were characterized by SEM, TEM, elemental analysis, TGA, nitrogen adsorption, SAXS, H-1, C-13, Si-29, and P-31 solid-state NMR spectroscopy, and powder XRD. These xerogels showed superior catalytic activity and selectivity in methylstyrene dimerization.