Structural and vibrational properties of Sb2S3: Practical methodologies for accelerated research and application of this low dimensional material.

Recently, the interest for the family of low dimensional materials has increased significantly due to the anisotropic nature of their fundamental properties. Among them, antimony sulfide (Sb2S3) is considered a suitable material for various solid-state devices. Although the main advantages and physicochemical properties of Sb2S3 are known, some doubtful information remains in literature and methodologies to easily assess its critical properties are missing. In this study, an advanced characterization of several types of Sb2S3 samples, involving the Rietveld refinement of structural properties, and Raman spectroscopy analysis, completed with lattice dynamics investigations reveal important insights into the structural and vibrational characteristics of the material. Based on the gathered data, fast, non-destructive, and non-invasive methodologies for assessment of the crystallographic orientation and point defect concentration of Sb2S3 are proposed. With a high resolution in-sample and in-situ assessment, these methodologies will serve for accelerating the research and application of Sb2S3 in the research field.

Confocal Raman imaging and chemometrics applied to solve forensic document examination involving crossed lines and obliteration cases by a depth profiling study.

This article describes a non-destructive analytical method developed to solve forensic document examination problems involving crossed lines and obliteration. Different strategies combining confocal Raman imaging and multivariate curve resolution-alternating least squares (MCR-ALS) are presented. Multilayer images were acquired at subsequent depth layers into the samples. It is the first time that MCR-ALS is applied to multilayer images for forensic purposes. In this context, this method provides a single set of pure spectral ink signatures and related distribution maps for all layers examined from the sole information in the raw measurement. Four cases were investigated, namely, two concerning crossed lines with different degrees of ink similarity and two related to obliteration, where previous or no knowledge about the identity of the obliterated ink was available. In the crossing line scenario, MCR-ALS analysis revealed the ink nature and the chronological order in which strokes were drawn. For obliteration cases, results making active use of information about the identity of the obliterated ink in the chemometric analysis were of similar quality as those where the identity of the obliterated ink was unknown. In all obliteration scenarios, the identity of inks and the obliterated text were satisfactorily recovered. The analytical methodology proposed is of general use for analytical forensic document examination problems, and considers different degrees of complexity and prior available information. Besides, the strategies of data analysis proposed can be applicable to any other kind of problem in which multilayer Raman images from multicomponent systems have to be interpreted.

Advanced lipid systems containing ß-carotene: stability under UV-vis radiation and application on porcine skin in vitro.

Phospholipid-based nanostructures, bicelles and bicosomes, are proposed as carriers of the antioxidant ß-carotene. The stability of these nanostructures and their carotenoid cargo was evaluated in an oxidation environment induced by ultraviolet A, visible and infrared A radiation (UVA-VIS-IRA). Additionally, the effect of these nanoaggregates on non-irradiated and irradiated skin microstructure was studied. The characterization of the lipid systems was performed using dynamic light scattering (DLS) and cryo-transmission electron microscopy (Cryo-TEM) and lipid peroxidation of the systems was determined by thiobarbituric acid (TBARS) assay. Moreover, the stability of ß-carotene in these lipid systems under this radiation was investigated using Raman spectroscopy. The results showed that the particle size of the bicelles did not change due to radiation. However, the size of the bicosomes increased slightly after irradiation. The TBARS assay showed the absence of peroxides in the bicelles and bicosomes, indicating the preservation of the lipid molecules under the radiation used. Raman experiments showed that bicosomes protected ß-carotene from degradation induced by radiation better than liposomes or dissolution in chloroform. With respect to the skin microstructure, no changes after irradiation were observed via freeze substitution transmission electron microscopy (FSTEM). This technique also showed the presence of vesicular structures in the stratum corneum (SC) after treatment with bicosomes.