Comparative Analysis of Flame Characteristics of Castor Oil and Some Other Inorganic Flame Retardants Used in Polyurethane Foam Systems

The flame characteristics of castor oil based foam and that of polyether foam impregnated with inorganic flame retardants (FR) were investigated. The polyether foams were impregnated with measured concentration of Antimony trioxide and Sodium bromide, Ammonium dihydrogen orthophosphate, Diammonium hydrogen orthophosphate, and Castor oil containing zero flame retardant. Incorporating these flame retardants into polyurethane formulations gave variable flame characteristics such as ignition time, flame propagation rate, after glow, char rate, add-on and glow time. These properties were measured as a function of concentration and type of flame retardant incorporated into the formulation. Result showed that ignition time and Add-On showed significant increase in this sequence- Castor oil>Ammonium dihydrogen orthophosphate> Diammonium hydrogen orthophosphate>Antimony trioxide/Sodium bromide, at all the different concentrations, while flame-propagation rate and After-glow decreased in the same sequence for all the FR used at different concentrations. However the %Char increased in a reverse order – Diammonium hydrogen orthophosphate>Ammonium dihydrogen orthophosphate>Antimony trioxide/Sodium bromide>Castor oil. These results show that castor oil is an effective flame retardant compared to the inorganic flame-retardants

The Effect of Trichlia emetica Leaf Extract on the Flammability of Flexible Polyurethane Foam

Due to the health and environmental consequences of conventional flame retardants the incorporation of new plant based flame retardants becomes imperative. Hence the choice of the leaves of Trichlia emetica as a flame retardant on flexible polyurethane foam based on Hausa folklore tradition that it is used as a flame retardant. Analysis of the treated flexible polyurethane foam revealed that add on percentage ranged from 9-21%, Ignition time between ranged within 6-14 sec, flame propagation rate 0.42-0.22 cm/s, after glow time decreased from 12 sec to 2 sec and char formation increased from 18% to 26%. Which indicated a modification of the flammability characteristics of the flexible polyurethane foamKeywords: Add on, After glow, Char, Flame propagation rate, Flame retardants, Ignition time, Polyurethan

Proximate and Mineral Composition of the Pulp of Chrysophyllum albidum Fruit

The proximate composition of Chrysophyllum albidum fruit pulp was determined. Mineral elements were determined using a tri-acid digestion method. The result of the proximate composition of the fruit pulp showed moisture content (64.00 ± 0.02%), ash (3.00 ± 0.02%), lipids (8.50 ± 0.02%), crude fibre (4.00 ± 0.02%), crude protein (0.24 ± 0.03%) and soluble carbohydrate (20.26±0.03%). The energy value of the fruit was found to be (663.12±0.60%kJ/100g) in the fruit pulp. Similarly, mineral analysis revealed potassium with (256.57± 5.77mg/100g), sodium (40.00 ± 0.00mg/100g), phosphorus (2.21 ± 0.03mg/100g), calcium (61.67±5.77mg/100g), magnesium (33.33 ± 20.21mg/100g), copper (0.94 ± 0.20mg/100g), zinc (0.26 + 0.10mg/100g), and iron (3.46+ 0.06). Others include heavy metal such as lead (0.09 ±0.08mg/100g), chromium (6.83± 6.26/100g) and cadmium was not detected. The pulp also contained appreciable amount of vitamin C (3.70 ± 0.17mg/100g). The results showed that the fruit pulp of Chrysophyllum albidum contained essential nutrients and mineral elements.Keywords: Chrysophyllum albidum, minerals, proximat

Intersection of phosphate transport, oxidative stress and TOR signalling in Candida albicans virulence

Phosphate is an essential macronutrient required for cell growth and division. Pho84 is the major high-affinity cell-surface phosphate importer of Saccharomyces cerevisiae and a crucial element in the phosphate homeostatic system of this model yeast. We found that loss of Candida albicans Pho84 attenuated virulence in Drosophila and murine oropharyngeal and disseminated models of invasive infection, and conferred hypersensitivity to neutrophil killing. Susceptibility of cells lacking Pho84 to neutrophil attack depended on reactive oxygen species (ROS): pho84-/- cells were no more susceptible than wild type C. albicans to neutrophils from a patient with chronic granulomatous disease, or to those whose oxidative burst was pharmacologically inhibited or neutralized. pho84-/- mutants hyperactivated oxidative stress signalling. They accumulated intracellular ROS in the absence of extrinsic oxidative stress, in high as well as low ambient phosphate conditions. ROS accumulation correlated with diminished levels of the unique superoxide dismutase Sod3 in pho84-/- cells, while SOD3 overexpression from a conditional promoter substantially restored these cells’ oxidative stress resistance in vitro. Repression of SOD3 expression sharply increased their oxidative stress hypersensitivity. Neither of these oxidative stress management effects of manipulating SOD3 transcription was observed in PHO84 wild type cells. Sod3 levels were not the only factor driving oxidative stress effects on pho84-/- cells, though, because overexpressing SOD3 did not ameliorate these cells’ hypersensitivity to neutrophil killing ex vivo, indicating Pho84 has further roles in oxidative stress resistance and virulence. Measurement of cellular metal concentrations demonstrated that diminished Sod3 expression was not due to decreased import of its metal cofactor manganese, as predicted from the function of S. cerevisiae Pho84 as a low-affinity manganese transporter. Instead of a role of Pho84 in metal transport, we found its role in TORC1 activation to impact oxidative stress management: overexpression of the TORC1-activating GTPase Gtr1 relieved the Sod3 deficit and ROS excess in pho84-/- null mutant cells, though it did not suppress their hypersensitivity to neutrophil killing or hyphal growth defect. Pharmacologic inhibition of Pho84 by small molecules including the FDA-approved drug foscarnet also induced ROS accumulation. Inhibiting Pho84 could hence support host defenses by sensitizing C. albicans to oxidative stress