ABSTRACT
The potential of saprophytic yeasts (Cryptococcus neoformans, Rhodoturula rubra and Toruiopsis candida) isolated from the apparently healthy fruits of lime fruits, orange and tomatoes for the control of postharvest yam (Discorea rotundata) rot caused by fungi was investigated. Treatments comprising three isolated pathogenic fungi (Aspergillus niger, Aspergillus flavus and Penicillium notatum) from rotten yams, each paired was set up in dual culture with one of the potential antagonists (saprophytic yeasts). The extent of rot reduction was evaluated by calculating the mean percentage (%) inhibition of the pathogens by antagonists. Pathogenicity test showed that A. niger, A. flavus and P. notatum induced rot in healthy yam tubers after fourteen days of inoculation at room temperature (28±2oC) with A. niger being the most virulent. The growth reduction or inhibition of A. niger, A. flavus and P. notatum was highest and significantly different (P<0.05) in C. neoformans (51.1, 51.7 and 50.0) and least in R. rubra (5.6, 4.9 and 6.4) respectively. The three biological antagonists could be used to control the rot of postharvest yam tubers. However, the field efficacies still need to be further investigated.
Keywords: Saprophytic yeast, Pathogenic, Antagonist, Postharvest, Discorea rotundata
ABSTRACT
The phonon and thermodynamic properties of fccYtterbium (Yb) rare-earth metal is investigated by performing density functional theory (DFT) and density functional perturbation theory (DFTP) calculations within the quasi harmonic approximation (QHA). Phonon dispersion and phonon density of states (DOS) were computed as well as linear thermal expansion as a function of temperature and constant volume specific heat as a function of temperature. Our calculated lattice constant for Yb is in general agreement with both theoretical and experimental results. Our result for phonon dispersion curve is in good agreement with available experimental result. Specific heat capacity of 46.89 J/mol.K is predicted for rare earth fccYb metal based on the thermodynamic properties computed within QHA from phonon DOS.
Keywords: Ytterbium, DFPT, Phonon, DOS, Specific heat capacity
ABSTRACT
This paper reports a sixteen month investigation of the pattern of variation of the physico-chemical parameters of Osse River was carried out from January 2003 to April 2004.Water samples for physical and chemical analysis were collected into a 250ml container and analyzed using standard methods. Results obtained showed marked seasonal fluctuations in the measured parameters with the rainy season months recording higher values than the dry season months. All parameters studied where significantly different among the stations investigated (P<0.05) except pH. There was strong positive correlation between total dissolved solids (TDS) and Electrical Conductivity (EC) and Salinity. Similar trend of correlation was also recorded between TDS on one hand and sulphate, calcium and turbidity. Chloride was also positively correlated with electrical conductivity and salinity.
KEYWORDS: Physicochemical parameters, water quality, seasonality, Osse River