Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has resulted in an unprecedented need for diagnostic testing that is critical in controlling the spread of COVID-19. We propose aportable infrared spectrometer with purpose-built transflection accessory for rapid point-of-care detection of COVID-19 markers in saliva. Initially,p urified virion particles were characterized with Raman spectroscopy, synchrotron infrared (IR) and AFM-IR. Adata set comprising 171 transflection infrared spectra from 29 subjects testing positive for SARS-CoV-2 by RT-qPCR and 28 testing negative, was modeled using Monte Carlo Double Cross Validation with 50 randomized test and model sets.T he testing sensitivity was 93 %( 27/29) with as pecificity of 82 %( 23/28) that included positive samples on the limit of detection for RT-qPCR. Herein, we demonstrate ap roof-of-concept high throughput infrared COVID-19 test that is rapid, inexpensive,portable and utilizes sample self-collection thus minimizing the risk to healthcare workers and ideally suited to mass screening.

Background: Although X-ray fluorescence microscopy is becoming a widely used technique for single-cell analysis, sample preparation for this microscopy remains one of the main challenges in obtaining optimal conditions for the measurements in the X-ray regime. The information available to researchers on sample treatment is inadequate and unclear, sometimes leading to wasted time and jeopardizing the experiment’s success. Many cell fixation methods have been described, but none of them have been systematically tested and declared the most suitable for synchrotron X-ray microscopy. Methods: The HEC-1-A endometrial cells, human spermatozoa, and human embryonic kidney (HEK-293) cells were fixed with organic solvents and cross-linking methods: 70% ethanol, 3.7%, and 2% paraformaldehyde; in addition, HEK-293 cells were subjected to methanol/ C3H6O treatment and cryofixation. Fixation methods were compared by coupling low-energy X-ray fluorescence with scanning transmission X-ray microscopy and atomic force microscopy. Results: Organic solvents lead to greater dehydration of cells, which has the most significant effect on the distribution and depletion of diffusion elements. Paraformaldehyde provides robust and reproducible data. Finally, the cryofixed cells provide the best morphology and element content results. Conclusion: Although cryofixation seems to be the most appropriate method as it allows for keeping cells closer to physiological conditions, it has some technical limitations. Paraformaldehyde, when used at the average concentration of 3.7%, is also an excellent alternative for X-ray microscopy.

In this work, polyvinylidene fluoride (PVDF) aerogels with a tailorable phase composition were prepared by following the crystallization-induced gelation principle. A series of PVDF wet gels (5 to 12 wt.%) were prepared from either PVDF–DMF solutions or a mixture of DMF and ethanol as non-solvent. The effects of the non-solvent concentration on the crystalline composition of the PVDF aerogels were thoroughly investigated. It was found that the nucleating role of ethanol can be adjusted to produce low-density PVDF aerogels, whereas the changes in composition by the addition of small amounts of water to the solution promote the stabilization of the valuable β and γ phases. These phases of the aerogels were monitored by FTIR and Raman spectroscopies. Furthermore, the crystallization process was followed by in-time and in situ ATR–FTIR spectroscopy. The obtained aerogels displayed specific surface areas > 150 m2 g−1, with variable particle morphologies that are dependent on the non-solvent composition, as observed by using SEM and Synchrotron Radiation Computed micro-Tomography (SR-μCT).

Wood polyphenolic extracts, commonly called tannins, are excellent candidates for the production of bioplastics due to their abundance in nature, their commercial availability, and their reactivity. In particular, they were tested as wood adhesives with several hardeners, but their low moisture resistance and their rigidity reduced their technological interest. In the present study, we combined regenerated silk (RS) with tannin-furanic formulations to improve their properties. Three-layer plywood glued with these several fully renewable tannin-silk-furanic adhesives were tested for their mechanical properties: the modulus of elasticity, the modulus of rupture, and both dry and wet shear strength were enhanced when 20 wt % of RS was added. Initially, the cross section of the prepared samples was investigated by scanning electron microscopy, indicating a good dispersion of RS within the tannin-furanic matrix. Afterward, thermomechanical analysis of the adhesive highlighted that RS slows down the polymerization rate, decreasing the cross-linking kinetics of polyfurfuryl alcohol. Chemical investigations through ATR-FTIR and 13C-NMR show the formation of covalent bonds between RS and the furanic matrix. In summary, the combination of bioresources from the vegetal and animal kingdom allows the manufacturing of fully bio-based adhesives with enhanced mechanical properties and water resistance. This represents an important breakthrough in the exploitation of polyphenols, opening perspectives for their application in material science.

Wood surface charring is a treatment method commonly employed to enhance weather protection and aesthetic appearance of building exteriors. This study aims to investigate the differences between two wood surface charring processes: the traditional Japanese method known as Yakisugi and an alternative charring technique industrially manufactured with a gas burner. The objective of the study was to assess whether a thicker layer after Yakisugi treatment has any advantages over a thinner layer after the alternative process. Vibrational spectroscopy techniques including UV resonance Raman (UVRR) and Fourier transform infrared (FTIR) spectroscopy, were utilized in conjunction with X-ray-micro-CT analysis. The findings revealed that ATR-FTIR spectroscopy detected the degradation of carbohydrates and changes in lignin within the charred surface, although both processes exhibited similar vibrational contributions. In contrast, UVRR spectroscopy provided insights into the carbonized layers, revealing spectral differences indicating variations in temperature during the charring processes. X-ray micro-CT analysis visually highlighted significant differences in the coal layers, suggesting distinct combustion profiles. Remarkably, the macrostructure of wood treated with Yakisugi remained intact despite a thicker charred layer compared to the alternative charring techniques. However, further investigations are required to assess the weather stability of the alternative charring method for a comprehensive understanding.

No abstract