Search results for "SAMPLE"
showing 10 items of 2270 documents
Three-dimensional real-time darkfield imaging through Fourier lightfield microscopy
2020
We report a protocol that takes advantage of the Fourier lightfield microscopy concept for providing 3D darkfield images of volumetric samples in a single-shot. This microscope takes advantage of the Fourier lightfield configuration, in which a lens array is placed at the Fourier plane of the microscope objective, providing a direct multiplexing of the spatio-angular information of the sample. Using the proper illumination beam, the system collects the light scattered by the sample while the background light is blocked out. This produces a set of orthographic perspective images with shifted spatial-frequency components that can be recombined to produce a 3D darkfield image. Applying the ade…
Nanosensors and other techniques for detecting nanoparticles in the environment
2014
Abstract: Detecting nanomaterials in the environment is a demanding task, not only because of the extremely small size of the particles and their potential sequestration and agglomeration, but also because of their unique physical and chemical characteristics. The aim of this review is to recommend a way forward on tackling the challenge of engineered nanomaterial detection in the environment. An overview will be presented of the available analytical techniques used for the detection and characterization of nanoparticles in environmental matrices including particle-size analysis, particle-fraction concentration counts, surface-area analysis, morphology, and particle chemical composition ana…
Removing striping artifacts in light-sheet fluorescence microscopy: a review
2022
Abstract In recent years, light-sheet fluorescence microscopy (LSFM) has found a broad application for imaging of diverse biological samples, ranging from sub-cellular structures to whole animals, both in-vivo and ex-vivo, owing to its many advantages relative to point-scanning methods. By providing the selective illumination of sample single planes, LSFM achieves an intrinsic optical sectioning and direct 2D image acquisition, with low out-of-focus fluorescence background, sample photo-damage and photo-bleaching. On the other hand, such an illumination scheme is prone to light absorption or scattering effects, which lead to uneven illumination and striping artifacts in the images, oriented…
Sample building orientation effect on porosity and mechanical properties in Selective Laser Melting of Ti6Al4V titanium alloy
2022
Abstract In recent decades, the focus of research has shifted towards new production technologies with the aim of optimizing production and reducing costs. These innovative technologies include additive manufacturing processes as Selective Laser Melting (SLM). The analysis of the literature on the identification of optimal building orientation to maximize the mechanical properties and minimize porosity of the final products highlights contrasting results, denoting that the thermomechanical complexity of the process, as associated with the variation of the building orientation, has not been fully clarified. A study in which the building orientation effect was evaluated together with the geom…
Determination of90Sr in environmental samples with resonance ionization spectroscopy in collinear geometry
1994
A new, fast technique for trace analysis of the radioactive isotopes89Sr and90Sr in environmental samples has been developed. Conventional mass separation is combined with resonance ionization spectroscopy in collinear geometry, which provides high selectivity and sensitivity. In addition, a chemical separation procedure for sample preparation has been developed. The described technique was used to determine the90Sr content in ≈ 870 m3 air samples collected near Munich during and shortly after the Chernobyl reactor accident in April 1986. The content of90Sr was measured to be 1.4 mBq per m3, corresponding to 1.6 × 109 atoms of90Sr per sample. This value is in good agreement with the results…
Formation of Optical Gradient in Chemical Solution-Derived PbZr[sub 0.52]Ti[sub 0.48]O[sub 3] Thin Films: Spectroscopic Ellipsometry Investigation
2009
Investigation using a variable angle spectroscopic ellipsometer revealed the influence of sample preparation conditions on sol-gel PbZr 0.52 Ti 0.48 O 3 (PZT 52/48) thin-film homogeneity that allows identification and further optimization of thin-film performance. Separate crystallization of the layers determined the optical gradient appearance, irrespective of the chemical solvents used in this work. A more refined analysis showed that a refractive index gradient was apparent in the samples in which lattice parameters strongly changed with thickness. For these films, energy-dispersive X-ray spectroscopy analysis showed significant variation in Pb and Zr. Additionally, complex dielectric fu…
X-ray powder diffraction and LIESST-effect of the spin transition material [Fe(bpp)2](NCS)2·2H2O
2006
Abstract We have studied the X-ray powder diffraction of the spin transition material [Fe(bpp)2](NCS)2 · 2H2O (bpp: 2,6-bis(pyrazol-3-yl)pyridine) at room temperature. Two crystallographic phases have been observed depending on the sample history of this material. The results obtained corroborate the earlier observations from magnetic and calorimetric studies. Relatively prolonged exposure of the sample to X-rays caused a structural change. LIESST and Reverse-LIESST effects, characterised by 57Fe Mossbauer spectroscopy, have been observed in this material.
Femtosecond digital lensless holographic microscopy to image biological samples
2013
The use of femtosecond laser radiation in digital lensless holographic microscopy (DLHM) to image biological samples is presented. A mode-locked Ti:Sa laser that emits ultrashort pulses of 12 fs intensity FWHM, with 800 nm mean wavelength, at 75 MHz repetition rate is used as a light source. For comparison purposes, the light from a light-emitting diode is also used. A section of the head of a drosophila melanogaster fly is studied with both light sources. The experimental results show very different effects of the pinhole size on the spatial resolution with DLHM. Unaware phenomena on the field of the DLHM are analyzed.
Computer vision profilometer: equipment and evaluation of measurements
1991
Abstract This paper describes a new equipment that measures roughness values by a computer vision (CV) technique. Measurements carried out by a CV profilometer are also evaluated. A laser source (power 2 mW), a cylindrical lens and a charge coupled device (CCD) TV-camera with a suitable optical system form an image of the profile of the sample under inspection. This image is then transformed into a binary image by thresholding and the line that divides the bright zone from the dark zone is the sample profile. From this line the characteristic roughness values can be calculated. The roughness measurements are carried out both by the CV profilometer and a stylus profilometer on eight specimen…
Transillumination imaging through biological tissue by single-pixel detection
2015
One challenge that has long held the attention of scientists is that of clearly seeing objects hidden by turbid media, as smoke, fog or biological tissue, which has major implications in fields such as remote sensing or early diagnosis of diseases. Here, we combine structured incoherent illumination and bucket detection for imaging an absorbing object completely embedded in a scattering medium. A sequence of low-intensity microstructured light patterns is launched onto the object, whose image is accurately reconstructed through the light fluctuations measured by a single-pixel detector. Our technique is noninvasive, does not require coherent sources, raster scanning nor time-gated detection…