Evaluation of traditional semi-hard Brazilian cheeses using chemometric tools to identify possible denomination fraud

This study aimed to evaluate and classify some of the main traditional Brazilian semi-hard cheeses, using multivariate tools to determine possible denomination fraud. Fifty-six samples of Minas Artisanal (MA), Colonial (AC), Minas Padrão (MP) and Meia Cura (MC) cheeses were analysed. All the evaluated parameters indicated high variability. PCA and HCA confirmed two groupings (AC and MP; and MA and MC) with high similarity. The DD-SIMCA method classified the cheeses with 83% accuracy. AC (48%) and MA (20%) cheeses were the most well classified in their respective denomination. These results were efficient in classifying groups and demonstrating the lack of authenticity regarding the denominations of these cheeses.     

Unexpected Quasi-Axial Conformer in Thermally Activated Delayed Fluorescence DMAC-TRZ,Pushing Green OLEDs to Blue

Hidden photophysics is elucidated in the very well-known thermally activated delayed fluorescence (TADF) emitter, DMAC-TRZ. A molecule that, based on its structure, is considered not to have more than one structural conformation. However, based on experimental and computational studies, two conformers, a quasi-axial (QA) and a quasi-equatorial (QE) are found, and the effect of their co-existence on both optical and electrical excitation isexplored. The relative small population of the QA conformer has a disproportionate effect because of its strong local excited state character. The energy transfer efficiency from the QA to the QE conformer is high, even at low concentrations, dependent on the host environment. The current accepted triplet energy of DMAC-TRZ is shown to originate from the QA conformer, completely changing the understanding of DMAC-TRZ. The contribution of the QA conformer in devices helps to explain the good performance of the material in non-doped organic light-emitting diodes (OLEDs). Moreover, hyperfluorescence (HF) devices, using v-DABNA emitter show direct energy transfer from the QA conformer to v-DABNA, explaining the relatively improved Förster resonance energy transfer efficiency compared to similar HF systems. Highly efficient OLEDs where green light (TADF-only devices) is converted to blue light (HF devices) with the maximum external quantum efficiency remaining close to 30% are demonstrated.