With the advent of low-cost and high-resolution digital cameras, and sophisticated photo editing software, digital images can be easily manipulated and altered. Although good forgeries may leave no ...visual clues of having been tampered with, they may, nevertheless, alter the underlying statistics of an image. Most digital cameras, for example, employ a single sensor in conjunction with a color filter array (CFA), and then interpolate the missing color samples to obtain a three channel color image. This interpolation introduces specific correlations which are likely to be destroyed when tampering with an image. We quantify the specific correlations introduced by CFA interpolation, and describe how these correlations, or lack thereof, can be automatically detected in any portion of an image. We show the efficacy of this approach in revealing traces of digital tampering in lossless and lossy compressed color images interpolated with several different CFA algorithms.
Magnetic skyrmions are topologically nontrivial particles with a potential application as information elements in future spintronic device architectures. While they are commonly portrayed as two ...dimensional objects, in reality magnetic skyrmions are thought to exist as elongated, tube-like objects extending through the thickness of the host material. The study of this skyrmion tube state (SkT) is vital for furthering the understanding of skyrmion formation and dynamics for future applications. However, direct experimental imaging of skyrmion tubes has yet to be reported. Here, we demonstrate the real-space observation of skyrmion tubes in a lamella of FeGe using resonant magnetic x-ray imaging and comparative micromagnetic simulations, confirming their extended structure. The formation of these structures at the edge of the sample highlights the importance of confinement and edge effects in the stabilisation of the SkT state, opening the door to further investigation into this unexplored dimension of the skyrmion spin texture.
The paper considers a new concept of alloy with high entropy (HEA) for biomedical applications. HEAs are different from the conventional metallic materials by more than five alloying elements, in ...proportions between 5% and 35% at., which may form simple solid solutions with BCC and/or FCC phases instead of complicated intermetallic ones. These specific features provide HEA with excellent mechanical properties (hardness, strength, malleability), oxidation and corrosion resistance, with potential applications in diverse industrial areas. The present tendency in the newest titanium alloys generation is the decrease of elasticity modulus, with the maintaining of high mechanical characteristics. Thus, the paper considers the system TiZrNbTaFe for biomedical applications obtained by powder metallurgy (PM) route, because HEAs prepared by this method show a greater homogeneity in their microstructure compared to the segregated microstructure of melted and cast HEAs. The influence of milling time, compaction and sintering on the microstructure and mechanical and corrosion properties of the new TiZrNbTaFe alloy were investigated. The obtained properties have shown a better mechanical biocompatibility in order to use this high entropy alloy as orthopedic or dental implants. The mechanical properties of the obtained alloys are better than those of biomaterials that are used in present.
We have previously described interstitial Cajal‐like cells (ICLC) in human atrial myocardium. Several complementary approaches were used to verify the existence of ICLC in the interstitium of rat or ...human ventricular myocardium: primary cell cultures, vital stainings (e.g.: methylene blue), traditional stainings (including silver impregnation), phase contrast and non‐conventional light microscopy (Epon‐embedded semithin sections), transmission electron microscopy (TEM) (serial ultrathin sections), stereology, immunohistochemistry (IHC) and immunofluorescence (IF) with molecular probes. Cardiomyocytes occupy about 75% of rat ventricular myocardium volume. ICLC represent ∼32% of the number of interstitial cells and the ratio cardiomyocytes/ICLC is about 70/1. In the interstitium, ICLC establish close contacts with nerve fibers, myocytes, blood capillaries and with immunoreactive cells (stromal synapses). ICLC show characteristic cytoplasmic processes, frequently two or three, which are very long (tens up to hundreds of μm), very thin (0.1‐0.5μm thick), with uneven caliber, having dilations, resulting in a moniliform aspect. Gap junctions between such processes can be found. Usually, the dilations are occupied by mitochondria (as revealed by Janus green B and Mito Tracker Green FM) and elements of endoplasmic reticulum. Characteristically, some prolongations are flat, with a veil‐like appearance, forming a labyrinthic system. ICLC display caveolae (about 1 caveola/1μm cell membrane length, or 2‐4% of the relative cytoplasmic volume, Mitochondria and endoplasmic reticulum (rough and smooth) occupy 5‐10% and 1‐2% of cytoplasmic volume, respectively. IHC revealed positive staining for CD34, EGFR and vimentin and, only in a few cases for CD117. IHC was negative for: desmin, CD57, tau, chymase, tryptase and CD13. IF showed that ventricular ICLC expressed connexin 43. We may speculate that possible ICLC roles might be: intercellular signaling (neurons, myocytes, capillaries etc.) and/or chemomechanical sensors. For pathology, it seems attractive to think that ICLC might participate in the process of cardiac repair/remodeling, arrhythmogenesis and, eventually, sudden death.
The unique stature of photographs as a definitive recording of events is being diminished due, in part, to the ease with which digital images can be manipulated and altered. Although good forgeries ...may leave no visual clues of having been tampered with, they may, nevertheless, alter the underlying statistics of an image. For example, we describe how resampling (e.g., scaling or rotating) introduces specific statistical correlations, and describe how these correlations can be automatically detected in any portion of an image. This technique works in the absence of any digital watermark or signature. We show the efficacy of this approach on uncompressed TIFF images, and JPEG and GIF images with minimal compression. We expect this technique to be among the first of many tools that will be needed to expose digital forgeries.
•Uncertainty estimation is of great demand for geotechnics, but DST standards ignore it.•OLS, IWLS and WLOC approaches are not suitable for uncertainty estimation in DST.•Hybrid OLS (HOLS) approach ...is highly recommended for uncertainty estimation in DST.•HOLS addresses correlated errors in both variables, including the heteroscedastic ones.•Determination of MU in DST has a critical role in evaluation of soil improvement rate.
A new Hybrid Ordinary Least Squares method, denoted HOLS, is proposed for the measurement uncertainty estimation in direct shear tests performed in geotechnical laboratories. The HOLS is designed to overcome the shortcoming of the test standards that ignore the measurement uncertainty estimation in the geotechnical laboratory tests. HOLS is in line with the geotechnical laboratory practice, mathematically accessible and easy to deploy its related calculations on common PC software. The HOLS takes into account the correlations among all the measurands used in direct shear test procedure. It provides better results in both cases of the homoscedastic and heteroscedastic data compared to other approaches, as the Ordinary Least Squares largely overestimates measurement uncertainties, while Iterative Weighted Least Squares and Weighted Line of Organic Correlation strongly underestimate them. The proposed method was validated by inter-comparison between published data. The worst-case strategy is advanced in case of feeble knowledge about errors correlations.
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Radio-frequency Plasma Enhanced Chemical Vapour Deposition (in different methane dilutions) was used to synthesize adherent and haemocompatible diamond-like carbon (DLC) films on medical grade ...titanium substrates. The improvement of the adherence has been achieved by interposing a functional buffer layer with graded composition Ti
x
TiC
1−x
(x = 0–1) synthesized by magnetron co-sputtering. Bonding strength values of up to ~67 MPa have been measured by pull-out tests. Films with different sp
3
/sp
2
ratio have been obtained by changing the methane concentration in the deposition chamber. Raman spectroscopy, X-ray photoelectron spectroscopy and X-ray diffraction were employed for the physical–chemical characterization of the samples. The highest concentration of sp
3
-C (~87 %), corresponding to a lower DLC surface energy (28.7 mJ/m
2
)
, was deposited in a pure methane atmosphere. The biological response of the DLC films was assayed by a state-of-the-art biological analysis method (surface enhanced laser desorption/ionization–time of flight mass spectroscopy), in conjunction with other dedicated testing techniques: Western blot and partial thromboplastin time. The data support a cause-effect relationship between sp
3
-C content, surface energy and coagulation time, as well as between platelet-surface adherence properties and protein adsorption profiles.
•Ripples obtained on carbon films after irradiation with visible ps laser pulses.•Amorphous carbon was transformed in nanographite following irradiation.•Ripples had a complex morphology, being made ...of islands of smaller ripples.•Hydrophilic carbon films became hydrophobic after surface structuring.
Thin films of carbon were synthesized by ns pulsed laser deposition in vacuum on silicon substrates, starting from graphite targets. Further on, the films were irradiated with a picosecond laser source emitting in visible at 532nm. After tuning of laser parameters, we obtained a film surface covered by laser induced periodical surface structures (LIPSS). They were investigated by optical, scanning electron and atomic force microscopy. It was observed that changing the irradiation angle influences the LIPSS covered area. At high magnification it was revealed that the LIPSS pattern was quite complex, being composed of other small LIPSS islands, interconnected by bridges of nanoparticles. Raman spectra for the non-irradiated carbon films were typical for a-C type of diamond-like carbon, while the LIPSS spectra were characteristic to nano-graphite. The pristine carbon film was hydrophilic, while the LIPSS covered film surface was hydrophobic.
► We deposit 5-(4-carboxyphenyl)-10,15,20-tris(4-phenoxyphenyl)-porphyrin (CPPOPP) thin films by MAPLE. ► AFM investigations have shown that thin films have a quasi-continuous morphology dependent on ...incident laser fluence. ► Chemical structure of CPPOPP thin films is preserved for laser fluence values within the range 200–300mJ/cm2. ► CPPOPP thin films are appropriate as a single mediator for glucose in the specific case of carbon paste screen-printed electrodes.
We report on the deposition of nanostructured porphyrin-base, 5(4-carboxyphenyl)-10,15,20-tris(4-phenoxyphenyl)-porphyrin thin films by matrix assisted pulsed laser evaporation onto silicon substrates with screen-printed electrodes. AFM investigations have shown that at 400mJ/cm2 fluence a topographical transition takes place from the platelet-like stacking porphyrin-based nanostructures in a perpendicular arrangement to a quasi-parallel one both relative to the substrate surface. Raman spectroscopy has shown that the chemical structure of the deposited thin films is preserved for fluences within the range of 200–300mJ/cm2. Cyclic voltammograms have demonstrated that the free porphyrin is appropriate as a single mediator for glucose in a specific case of screen-printed electrodes, suggesting potential for designing a new class of biosensors.
•Study of spatter generated during laser irradiation of an aluminium nanocomposite.•Number of droplets was 1.5–3 times higher for laser in depth vs surface focused beams.•High speed imaging revealed ...particles exploding in flight similar to a fireworks effect.•Three methods were selected for droplets removal in situ and the results are analyzed.
Spatter generated during laser irradiation of an aluminium alloy nanocomposite (AlMg5 reinforced with Al2O3 nanoparticles) was monitored by high speed imaging. Droplets trajectory and speed were assessed by computerized image analysis. The effects of laser peak power and laser focusing on the plume expansion and expulsed droplet speeds were studied in air or under argon flow. It was found that the velocity of visible droplets expulsed laterally or at the end of the plume emission from the metal surface was not dependent on the plasma plume speed. The neighbouring area of irradiation sites was studied by optical and scanning electron microscopy. Droplets deposited on the surface were classified according to their size and counted using a digital image processing software. It was observed that the number of droplets on surface was 1.5–3 times higher when the laser beam was focused in depth as compared to focused beams, even though the populations average diameter were comparable. Three methods were selected for removing droplets in situ, during plume expansion: an argon gas jet crossing the plasma plume, a fused silica plate collector transparent to the laser wavelength placed parallel to the irradiated surface and a mask placed onto the aluminium composite surface. The argon gas jet was efficient only for low power irradiation conditions, the fused silica plate failed in all tested conditions and the mask was successful for all irradiation regimes.
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