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Bostrycoidin is one of the pigments produced by the Fusarium genus of fungi. On the one hand, it has significant pharmacological importance, while on the other hand, it serves as a presence marker of Fusarium infection in useful grain crops, fruits, and soils. In this regard, the structural and optical properties of the bostrycoidin molecule were studied in the framework of density functional theory (DFT). The most stable geometry as well as higher-energy conformers and tautomers were investigated. The lowest-energy tautomer was found to be about 3 kcal/mol higher in energy than the most stable structure, resulting in relatively low population of this state. The obtained conformational rotamers associated with the rotation of the OMe group possess similar energy. The vibrational spectrum was modeled for the most stable conformer, and the most active peaks in the IR absorbance spectrum were assigned. Moreover, the electronic absorption spectrum was simulated within the time-dependent DFT approach. The obtained theoretical spectrum is in good agreement with the experimental data and the theoretically calculated longest-wavelength transition (HOMO–LUMO) was about 498 nm. [ABSTRACT FROM AUTHOR]

Photographic artifacts carry important historical and cultural information. Materials used in photography at the turn of the XIXth and XXth centuries tend to degrade both over time and if the temperature and humidity conditions of storage are violated. In this connection, the question arises of determining the safety degree and monitoring the condition of photographic materials. Close attention should be paid to photographic materials that become flammable as a result of decomposition. This class of objects includes photographic films based on cellulose nitrate. This study was aimed at examining 100 negatives and stereonegatives from the collection of Karl Kosse dating from 1902 to 1917 as typical examples of these hazard class objects. The degradation of individual negatives was accompanied by a significant change in color—yellowing. The base of photographic negatives (cellulose nitrate and camphor) was determined by Raman spectroscopy, and the presence of a gelatin layer was determined by ATR-FTIR spectroscopy. Using chemometric analysis methods based on the RGB components of digital photos of negatives, an approach has been proposed for determining the state of degradation. The use of the support vector machine approach allows for obtaining a decision boundary, which can be later used to analyze a large data array. [ABSTRACT FROM AUTHOR]

The quality of food is one of the emergent points worldwide. Many microorganisms produce toxins that are harmful for human and animal health. In particular, mycotoxins from Fusarium fungi are strictly controlled in cereals. Simple and robust biosensors are necessary for 'in field' control of the crops and processed products. Nucleic acid-based sensors (aptasensors) offer a new era of point-of-care devices with excellent stability and limits of detection for a variety of analytes. Here we report the development of a surface-enhanced Raman spectroscopy (SERS)-based aptasensor for the detection of T-2 and deoxynivalenol in wheat grains. The aptasensor was able to detect as low as 0.17% of pathogen fungi in the wheat grains. The portable devices, inexpensive SERS substrate, and short analysis time encourage further implementation of the aptasensors outside of highly equipped laboratories. [ABSTRACT FROM AUTHOR]

Gold nanoparticles are widely used as local heaters under optical excitation. Hybrid molecular-plasmon nanostructures based on gold nanoparticles and water-soluble porphyrin have been developed. A colloidal solution of gold nanoparticles was obtained by laser ablation of metallic gold in water, ensuring its highest chemical purity. The hybrid nanostructures formation was performed due to the Coulomb interaction of cationic porphyrin and gold nanoparticles. The revealed functional properties of hybrid nanostructures make them promising for controllable nano-heater applications (for example, photothermal therapy). Gold nanoparticles act as heaters, whereas porphyrin serves as a fluorescent thermometer with a single optical excitation. [ABSTRACT FROM AUTHOR]