Effect of annealing on the functionality of Bambara groundnut (Vigna subterranea) starch–palmitic acid complex

Bambara groundnut is an underutilised African leguminous crop. This study investigated the effect of annealing on the complexing ability and functionality of Bambara groundnut starch with palmitic acid. Corn starch was included as the reference. Annealing created cracks and pores on the surface of Bambara groundnut and corn starches, respectively. Bambara groundnut starch had significantly higher amylose content, higher peak and final viscosities than corn starch. The peak viscosities of native Bambara groundnut and corn starches significantly reduced with palmitic acid addition. Greater reduction in peak viscosities was observed when the annealed starches were complexed with palmitic acid, suggesting that more palmitic acid was complexed after annealing. This was confirmed by XRD peaks and melting enthalpies. Pasting of native Bambara groundnut and corn starches with palmitic acid resulted in the formation of type I V‐amylose complexes, while type II complexes were formed from annealed starches pasted with palmitic acid.     

Studying the cellulolytic activity of microorganisms isolated from stained painted walls with reference to certain factors: a cross sectional study

Investigations of enzymatic activities amongst microbial species on stained painted walls are not common especially in the tropics. Meanwhile, an organism’s enzymatic activity is a key index of its biodegradation potential. We conducted a cross-sectional study to assess the cellulolytic profiles of microorganisms isolated from stained painted buildings. A total of eight microorganisms comprising one bacterium [Pseudomonas aeruginosa CH01 (KY511067.1)] and seven fungi [Meyerozyma guillermondii MB14B1 (LT615287.1), Meyerozyma caribbica CBS:5674 (KY104219.1), Aspergillus aculeatus A1.9 (EU833205.1), Aspergillus sp. SL2 (KC178662.1), Fusarium proliferatum2705 (EU272509.1), Cerrena sp. N10CC2a (FJ010208.1) and Candida tropicalis UZ31_13 (KM361510.1)] were utilized for the study. The results showed that all isolates possessed exoglucanase and endoglucanase activities ranging from 0.174 to 1.554 IU/ml and 0.062 to 2.120 IU/ml, respectively. Analysis of the interplay of organism cellulolytic activity at various environmental conditions showed that endoglucanase activity was optimal in Cerrena sp., while the highest exoglucanase activity was recorded in P. aeruginosa.     

Effect of Deposition Temperature on Some Properties of MOCVD Molybdenum Sulphide Thin Films

Molybdenum sulphide thin films were deposited on sodalime glass, silicon Wafer and stainless steel （AISI 304L） substrates using Metal Organic Chemical Vapour Deposition （MOCVD） technique at temperatures ranging from 360 ℃ to 450 ℃. The films were characterized using Rutherford Backscattering Spectroscopy （RBS）, Ultraviolet-Visible Spectroscopy, Four point probe technique, Scanning Electron Microscopy （SEM） and Atomic Force Microscopy （AFM）. Elemental analysis showed that the S/Mo ratio increases from 1.22 to 2.33 with increasing temperature. The optical band gap varies from 1.69 eV to 1.79 eV as deposition temperature increases. The electrical conductivity ranging from 0.5 Ω-1 cm-1 to 1.30 Ω-1 also depends on deposition temperature. SEM micrographs of the films showed the layered structure of the film with an estimated grain size that increases from 1.6 μm to 2.4 μm as the deposition temperature increases. This study demonstrates that the properties of the films depend on the deposition temperature.