An expanded palette of fluorogenic HaloTag probes with enhanced contrast for targeted cellular imaging

We report on new fluorogenic HaloTag probes based on a molecular rotor design. Thanks to their viscosity-sensitive emission, the probes light-up upon reaction with the protein self-labeling tag HaloTag. The palette of probes cover an emission range from green to red and exhibit remarkably low non-specific signal that enabled wash-free targeted imaging of intracellular organelles and proteins with good contrast in live Hela cells.

Assessing the Potential of Molecular Imaging for Myelin Quantification in Organotypic Cultures

Ex vivo models for the noninvasive study of myelin-related diseases represent an essential tool to understand the mechanisms of diseases and develop therapies against them. Herein, we assessed the potential of multimodal imaging traceable myelin-targeting liposomes to quantify myelin in organotypic cultures. Methods: MRI testing was used to image mouse cerebellar tissue sections and organotypic cultures. Demyelination was induced by lysolecithin treatment. Myelin-targeting liposomes were synthetized and characterized, and their capacity to quantify myelin was tested by fluorescence imaging. Results: Imaging of freshly excised tissue sections ranging from 300 µm to 1 mm in thickness was achieved with good contrast between white (WM) and gray matter (GM) using T2w MRI. The typical loss of stiffness, WM structures, and thickness of organotypic cultures required the use of diffusion-weighted methods. Designed myelin-targeting liposomes allowed for semiquantitative detection by fluorescence, but the specificity for myelin was not consistent between assays due to the unspecific binding of liposomes. Conclusions: With respect to the sensitivity, imaging of brain tissue sections and organotypic cultures by MRI is feasible, and myelin-targeting nanosystems are a promising solution to quantify myelin ex vivo. With respect to specificity, fine tuning of the probe is required. Lipid-based systems may not be suitable for this goal, due to unspecific binding to tissues.

Epoxy/alumina composite coating on welded steel 316L with excellent wear and anticorrosion properties

The main purpose of this study is to elaborate anticorrosive coatings for the welded steel 316L, since this later is widely used in industrial field. Hence, within this work we have studied the electrochemical behaviour of different zones of the welded steel 316 in 1 M HCl media. The macrography study of the welded steel has revealed the different areas with a good contrast. We have stated three different zones, namely; melted zone (MZ), heat affected zone (HAZ) and base metal zone (BM). Impedance studies on welded steel 316L were conducted in 1 M HCl solution, coating of Epoxy/Alumina composite was applied on different zones, in order to reveal the anti-corrosion efficiency in each zone. Scanning electron microscopy (SEM) analysis was undertaken in order to check how far the used coating in such aggressive media protects the studied zones and these findings were assessed by water contact angle measurements. The choice of this coating is based on the cost and the safety. We concluded that the Epoxy/Alumina composite has a good protecting effect regarding welded steel in aggressive media.

Artifact-Free Single Image Defogging

In this paper, we present a novel defogging technique, named CurL-Defog, with the aim of minimizing the insertion of artifacts while maintaining good contrast restoration and visibility enhancement. Many learning-based defogging approaches rely on paired data, where fog is artificially added to clear images; this usually provides good results on mildly fogged images but is not effective for difficult cases. On the other hand, the models trained with real data can produce visually impressive results, but unwanted artifacts are often present. We propose a curriculum learning strategy and an enhanced CycleGAN model to reduce the number of produced artifacts, where both synthetic and real data are used in the training procedure. We also introduce a new metric, called HArD (Hazy Artifact Detector), to numerically quantify the number of artifacts in the defogged images, thus avoiding the tedious and subjective manual inspection of the results. HArD is then combined with other defogging indicators to produce a solid metric that is not deceived by the presence of artifacts. The proposed approach compares favorably with state-of-the-art techniques on both real and synthetic datasets.

Negative-tone molecular glass photoresist for high-resolution electron beam lithography

A low molecular weight organic compound containing bis-phenol A backbone (BPA-6OH) is reported as a negative-tone photoresist. This material has a high glass transition temperature and excellent thermal stability. A good contrast, well-resolved line pattern around 73.4 nm and sensitivity of 52 µC cm −2 can be received for negative-tone molecular glass photoresist upon exposure in electron beam lithography system. It indicates that the negative-tone molecular glass photoresist is one of the promising candidates for use in electron beam lithography.

Improving the Computational Complexity of Artificial Ultrasound Imaging Using a Combination of Independent Component Analysis and Adaptive Filter

Purpose: The artificial aperture imaging method owns a good contrast in the data recording and imaging process. However, this method is very time consuming that prevents its practical implementation. Materials and Methods: In this paper, the separated waveforms are sent by two elements together, instead of a single element, and the combination of the methods of independent component analysis and adaptive filtering both are used to extract different components in the received echoes. The obtained result illustrates that the imaging is performed in less time, and the computational complexity of this method is declined. Results and Conclusion: The proposed algorithm has been evaluated on two sets of simulated data and experimental data. The results indicate that the proposed method in the point phantom mode is only 1.5% worse in the resolution than the conventional artificial aperture method. Also, from the contrasting viewpoint, the proposed method has made the CR parameter worse by about 1.34dB than the conventional artificial aperture method. These adverse points of resolution and contrast in the proposed method are neglected than the conventional artificial aperture method because of a slight decrease in image quality than the artificial aperture method. However, the proposed method improves the computational complexity by 45% than the conventional artificial aperture method. As a result, it has brought the researchers closer to the practical implementation of artificial aperture imaging.

Tetrakis-(N-methyl-4-pyridinium)-porphyrin as a diamagnetic chemical exchange saturation transfer (diaCEST) MRI contrast agent

Easily synthesizable tetrakis-(N-methyl-4-pyridinium)-porphyrin as a diaCEST agent that shows nearly pH independent good contrast in a wide range of pH.

A QUÍMICA DE PRODUTOS NATURAIS APLICADOS A REVELADORES DE IMPRESSÕES DIGITAIS LATENTES

THE CHEMISTRY OF NATURAL PRODUCTS APPLIED TO LATENT FINGERMARK DEVELOPERS. Natural formulations have attracted great interest of many researchers regarding their use as latent fingermark developers powders due their important characteristics as the presence of natural pigments in these materials that offer a good contrast on the applied surface and also luminescent properties, which facilitates the visualization of minutiae in problematic substrates such as multicolored surfaces. In addition, natural powders present low toxicity, are widely available and economically viable. In this sense, the present work addresses the application of several natural products to enhance fingermarks visualization. The natural products were obtained from various sources such as seaweed, spices as well as other sources such as terrestrial and herbaceous plants. The evaluated powders are composed by compounds as chlorophyll, phycocyanins, curcumins, lawsone, fatty acids, coumarins, flavonoids and terpenes. These powders showed good adhesion to latent fingermarks, with similar or superior efficiency to the available powders on different surfaces with clear visualization of the minutiae. The development of new powders applicable to papiloscopy are extremely important since the conventional available powders, besides being expensive, are imported and within the national context there is a great lack of these revealing materials within forensic investigations by the Federal Police and in laboratories of research.

A coded aperture microscope for X-ray fluorescence full-field imaging

The design and construction of an instrument for full-field imaging of the X-ray fluorescence emitted by a fully illuminated sample are presented. The aim is to produce an X-ray microscope with a few micrometers spatial resolution, which does not need to scan the sample. Since the fluorescence from a spatially inhomogeneous sample may contain many fluorescence lines, the optic which will provide the magnification of the emissions must be achromatic, i.e. its optical properties must be energy-independent. The only optics which fulfill this requirement in the X-ray regime are mirrors and pinholes. The throughput of a simple pinhole is very low, so the concept of coded apertures is an attractive extension which improves the throughput by having many pinholes, and retains the achromatic property. Modified uniformly redundant arrays (MURAs) with 10 µm openings and 50% open area have been fabricated using gold in a lithographic technique, fabricated on a 1 µm-thick silicon nitride membrane. The gold is 25 µm thick, offering good contrast up to 20 keV. The silicon nitride is transparent down into the soft X-ray region. MURAs with various orders, from 19 up to 73, as well as their respective negative (a mask where open and closed positions are inversed compared with the original mask), have been made. Having both signs of mask will reduce near-field artifacts and make it possible to correct for any lack of contrast.

The Development of Latent Fingermarks for Visualization by Using AuNPs@AuNCs Core/Shell Nanoparticles

A method for in situ preparation of fluorescent AuNPs@AuNCs core/shell nanoparticles by the template of BSA coated gold nanoparticles was developed. The as-prepared AuNPs@AuNCs core/shell nanoparticles possessed advantages such as uniform size, improved monodispersity and excellent fluorescence. The AuNPs@AuNCs core/shell nanoparticles in powder and suspension form were applied to the detection of latent fingermark due to the above properties. The developed latent fingermarks by AuNPs@AuNCs core/shell powder on various surfaces can exhibit excellent ridge details with good contrast between the fingermarks and the substrate. Moreover, under alternative light sources, the latent fingermarks developed with AuNPs@AuNCs core/shell powder work well.