Synthesis of styrene maleic anhydride copolymer grafted graphene and its dispersion in aqueous solution.

In this study, three simple methods were described to synthesize covalently functionalized graphene nanoplatelets (GNPs) with poly(styrene-co-maleic anhydride) (SMA) via ester linkages. Furthermore, the dispersibility of modified GNPs in aqueous solution was characterized by several techniques. Anchoring of SMA long-chains on GNPs via chemical bonds was confirmed by Fourier transform infrared spectroscopy. Furthermore, field emission scanning electron microscopy analysis indicated that the SMA unevenly covered the surface and edges of the GNPs. Solubility measurements showed that the modified GNPs prepared by the designed method had excellent dispersibility in aqueous solution, and the grafting rate of modified GNPs showed an obvious positive correlation with the concentration in aqueous solution as revealed by ultraviolet absorbency and thermogravimetric analysis results. Markedly, the modified GNPs during ultrasonic treatment exhibited better dispersibility and grafting rate compared to others. Moreover, the experimental results confirmed that GNP concentration reached up to 0.32 mg mL-1 in aqueous solution and the grafting rate was 18.02%. The content of SMA had little effect on grafting rate; however, the ultrasonic duration significantly affected the process.

A multivariate approach using attenuated total reflectance mid-infrared spectroscopy to measure the surface mannoproteins and ß-glucans of yeast cell walls during wine fermentations.

Yeast cells possess a cell wall comprising primarily glycoproteins, mannans, and glucan polymers. Several yeast phenotypes relevant for fermentation, wine processing, and wine quality are correlated with cell wall properties. To investigate the effect of wine fermentation on cell wall composition, a study was performed using mid-infrared (MIR) spectroscopy coupled with multivariate methods (i.e., PCA and OPLS-DA). A total of 40 yeast strains were evaluated, including Saccharomyces strains (laboratory and industrial) and non-Saccharomyces species. Cells were fermented in both synthetic MS300 and Chardonnay grape must to stationery phase, processed, and scanned in the MIR spectrum. PCA of the fingerprint spectral region showed distinct separation of Saccharomyces strains from non-Saccharomyces species; furthermore, industrial wine yeast strains separated from laboratory strains. PCA loading plots and the use of OPLS-DA to the data sets suggested that industrial strains were enriched with cell wall proteins (e.g., mannoproteins), whereas laboratory strains were composed mainly of mannan and glucan polymers.