63 research outputs found
Quantifying colors at micrometer scale by colorimetric microscopy (C-Microscopy) approach
The color is the primal property of the objects around us and is direct manifestation of light-matter interactions. The color information is used in many different fields of science, technology and industry to investigate material properties or for identification of concentrations of substances. Usually the color information is used as a global parameter in a macro scale. To quantitatively measure color information in micro scale one needs to use dedicated microscope spectrophotometers or specialized micro-reflectance setups. Here, the Colorimetric Microscopy (C-Microscopy) approach based on digital optical microscopy and a free software is presented. The C-Microscopy approach uses color calibrated image and colorimetric calculations to obtain physically meaningful quantities i.e., dominant wavelength and excitation purity maps at micro level scale. This allows for the discovery of the local color details of samples surfaces. Later, to fully characterize the optical properties, the hyperspectral reflectance data at micro scale (reflectance as a function of wavelength for a each point) are colorimetrically recovered. The C-Microscopy approach was successfully applied to various types of samples i.e., two metamorphic rocks unakite and lapis lazuli, which are mixtures of different minerals; and to the surface of gold 99.999 % pellet, which exhibits different types of surface features. The C-Microscopy approach could be used to quantify the local optical properties changes of various materials at microscale in an accessible way. The approach is freely available as a set of python jupyter notebooks
Leading Modes of the 3pi0 production in proton-proton collisions at incident proton momentum 3.35GeV/c
This work deals with the prompt pp-->pp3pi0 reaction where the 3pi0 do not
origin from the decay of narrow resonances like \eta(547), \omega(782),
\eta'(958). The reaction was measured for the proton beam momentum of 3.35GeV/c
with the WASA-at-COSY detector setup. The dynamics of the reaction is
investigated by Dalitz and Nyborg plots studies. The reaction is described by
the model assuming simultaneous excitation of two baryon resonances
\Delta(1232) and N*(1440) where resonances are identified by their unique
decays topology on the missing mass of two protons MMpp dependent Dalitz and
Nyborg plots. The ratio
R=\Gamma(N*(1440)->N\pi\pi)/\Gamma(N*(1440)->\Delta(1232)\pi->N\pi\pi)= 0.039
+- 0.011(stat.) +- 0.008(sys.) is measured for the first time in a direct way.
It shows that the {N*(1440)->\Delta(1232)\pi->N\pi\pi} decay is a leading mode
of 3pi0 production. It is also shown that the MMpp is very sensitive to the
structure of the spectral line shape of the N*(1440) resonance as well as on
the interaction between the \Delta(1232) and N*(1440) resonances. The multipion
spectroscopy - a precision tool to directly access the properties of baryon
resonances is considered.
The pp-->pp\eta(3pi0) reaction was also measured simultaneously. It is shown
that the {\eta} production mechanism via N*(1535) is 43.4 +- 0.8(stat.) +-
2.0(sys.) of the total production, for the {\eta} momentum in the CM system
q_\eta^CM=0.45-0.7GeV/c. First time momentum dependence of the {\eta} angular
distribution is seen, the strongest effect is observed for the
cos(\theta_\eta^CM) distribution.Comment: PhD Thesis prepared at the Nuclear Physics Department of the
Jagiellonian University, Cracow, Poland, 201
Physics of EtaPrime->Pi+Pi-Eta and EtaPrime->Pi+Pi-Pi0 decays
The article describes experimental status of EtaPrime->Pi+Pi-Eta and
EtaPrime->Pi+Pi-Pi0 decays. A theoretical framework used for description of the
decays mechanism is also reviewed. The possibilities for the measurements with
WASA-at-COSY are mentioned.Comment: Proceedings from Symposium on Meson Physics at COSY-11 and
WASA-at-COSY, Cracow, 17-22 June 200
Automatic microscopic image analysis by moving window local Fourier Transform and Machine Learning
Analysis of microscope images is a tedious work which requires patience and time, usually done manually by the microscopist after data collection. The results obtained in such a way might be biased by the human who performed the analysis. Here we introduce an approach of automatic image analysis, which is based on locally applied Fourier Transform and Machine Learning methods. In this approach, a whole image is scanned by a local moving window with defined size and the 2D Fourier Transform is calculated for each window. Then, all the Local Fourier Transforms are fed into Machine Learning processing. Firstly, a number of components in the data is estimated from Principal Component Analysis (PCA) Scree Plot performed on the data. Secondly, the data are decomposed blindly by Non-Negative Matrix Factorization (NMF) into interpretable spatial maps (loadings) and corresponding Fourier Transforms (factors). As a result, the microscopic image is analyzed and the features on the image are automatically discovered, based on the local changes in Fourier Transform, without human bias. The user selects only a size and movement of the scanning local window which defines the final analysis resolution. This automatic approach was successfully applied to analysis of various microscopic images with and without local periodicity i.e. atomically resolved High Angle Annular Dark Field (HAADF) Scanning Transmission Electron Microscopy (STEM) image of Au nanoisland of fcc and Au hcp phases, Scanning Tunneling Microscopy (STM) image of Au-induced reconstruction on Ge(001) surface, Scanning Electron Microscopy (SEM) image of metallic nanoclusters grown on GaSb surface, and Fluorescence microscopy image of HeLa cell line of cervical cancer. The proposed approach could be used to automatically analyze the local structure of microscopic images within a time of about a minute for a single image on a modern desktop/notebook computer and it is freely available as a Python analysis notebook and Python program for batch processing
Preformulation studies on solid self-emulsifying systems in powder form containing magnesium aluminometasilicate as porous carrier
The influence of alkaline and the neutral grade of magnesium aluminometasilicate as a porous solid carrier for the liquid self-emulsifying formulation with ibuprofen is investigated. Ibuprofen is dissolved in Labrasol, then this solution is adsorbed on the silicates. The drug to the silicate ratio is 1:2, 1:4, and 1:6, respectively. The properties of formulations obtained are analyzed, using morphological, porosity, crystallinity, and dissolution studies. Three solid self-emulsifying (S-SE) formulations containing Neusilin SG2 and six consisting of Neusilin US2 are in the form of powder without agglomerates. The nitrogen adsorption method shows that the solid carriers are mesoporous but they differ in a specific surface area, pore area, and the volume of pores. The adsorption of liquid SE formulation on solid silicate particles results in a decrease in their porosity. If the neutral grade of magnesium aluminometasilicate is used, the smallest pores, below 10 nm, are completely filled with liquid formulation, but there is still a certain number of pores of 40–100 nm. Dissolution studies of liquid SEDDS carried out in pH = 1.2 show that Labrasol improves the dissolution of ibuprofen as compared to the pure drug. Ibuprofen dissolution from liquid SE formulations examined in pH of 7.2 is immediate. The adsorption of the liquid onto the particles of the silicate causes a decrease in the amount of the drug released. Finally, more ibuprofen is dissolved from S-SE that consist of the neutral grade of magnesium aluminometasilicate than from the formulations containing the alkaline silicate
Nanostructure phase and interface engineering via controlled Au self-assembly on GaAs(001) surface
We have investigated the temperature-dependent morphology and composition
changes occurring during a controlled self-assembling of thin Au film on the
Gallium arsenide (001) surface utilizing electron microscopy at nano and atomic
levels. It has been found that the deposition of 2 ML of Au at a substrate
temperature lower than 798 K leads to the formation of pure Au nanoislands. For
the deposition at a substrate temperature of about 798 K the nanostructures of
the stoichiometric AuGa phase were/had been grown. Gold deposition at higher
substrate temperatures results in the formation of octagonal nanostructures
composed of an AuGa2 alloy. We have proved that the temperature-controlled
efficiency of Au-induced etching-like of the GaAs substrate follows in a
layer-by-layer manner leading to the enrichment of the substrate surface in
gallium. The excess Ga together with Au forms liquid droplets which, while
cooling the sample to room temperature, crystallize therein developing
crystalline nanostructures of atomically-sharp interfaces with the substrate.
The minimal stable cluster of 3 atoms and the activation energy for the surface
diffusion Ed=0.816+-0.038eV was determined. We show that by changing the
temperature of the self-assembling process one can control the phase, interface
and the size of the nanostructures formed
Synthesis of new metastable nanoalloys of immiscible metals with a pulse laser technique
The generation of nanoalloys of immiscible metals is still a challenge using conventional methods. However, because these materials are currently attracting much attention, alternative methods are needed. In this article, we demonstrate a simple but powerful strategy for the generation of a new metastable alloy of immiscible metals. Au_{1-X}Ni_{X} 3D structures with 56 at% of nickel in gold were successfully manufactured by the pulsed laser irradiation of colloidal nanoparticles. This technology can be used for preparing different metastable alloys of immiscible metals. We hypothesise that this technique leads to the formation of alloy particles through the agglomerations of nanoparticles, very fast heating, and fast cooling/solidification. Thus, we expect that our approach will be applicable to a wide range of inorganic solids, yielding even new metastable solids that fail to be stable in the bulk systems, and therefore do not exist in Nature
Density functional theory study of Au-fcc/Ge and Au-hcp/Ge interfaces
In recent years, nanostructures with hexagonal polytypes of gold have been synthesised, opening new possibilities in nanoscience and nanotechnology. As bulk gold crystallizes in the fcc phase, surface effects can play an important role in stabilizing hexagonal gold nanostructures. Here, we investigate several heterostructures with Ge substrates, including the fcc and hcp phases of gold that have been observed experimentally. We determine and discuss their interfacial energies and optimized atomic arrangements, comparing the theory results with available experimental data. Our DFT calculations for the Au-fcc(011)/Ge(001) junction show how the presence of defects in the interface layer can help to stabilize the atomic pattern, consistent with microscopic images. Although the Au-hcp/Ge interface is characterized by a similar interface energy, it reveals large atomic displacements due to significant mismatch. Finally, analyzing the electronic properties, we demonstrate that Au/Ge systems have metallic character, but covalent-like bonding states between interfacial Ge and Au atoms are also present
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