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December 2022
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Interactions in Binary Mixed Solvents of Propylene carbonate +Diethyl carbonate and Propylenecarbonate+Dimethylformamide at 298.15K
Edimeh Agatha, Ekpete Ozioma, Kpee Friday, Ayasen Kemeakegha, Ayasen Kemeakegha
ABSTRACT: In thermodynamics, it is essential to be aware of the various forms of intermolecular interactions taking place in solvent mixtures. The study was carried out to evaluate the interactions in mixed binary organic solvents of propylene carbonate (PC) and Diethyl carbonate (DEC) and Propylene carbonate and Dimethylformamide (DMF) at 298.15K. The densities and viscosities of binary mixed organic solvents, propylene carbonate and Diethyl carbonate and Propylene carbonate and Dimethylformamide were measured at a varied percentage solvent constitution of 298.15K. The excess volumes VE and excess viscosities ��E were calculated from the density and viscosity values obtained fromexperimentst. These were fitted into the Redlich-Kister polynomial equation to obtain the fitting coefficients and the corresponding standard deviations. Excess volume values for PC+DEC mixtures were positive at lower mole fractions of PC and negative at higher mole fractions, while the excess volume values obtained for the PC+DMF mixtures were all negative. The excess viscosities for both PC+DEC and PC+DMF were negative over the whole span of solvent compositions. These behaviors have been attributed to the dominance of weak dispersion forces and strong attractive interactions between the mixed solvent components. As a result, there are more intermolecular interactions than solvent-solvent interactions in solvent systems. The mixed systems could be employed as possible mixed organic electrolyte solvents and other solvent applications, as the data provided can act as a guide.
[ FULL TEXT PDF 1-7 ] DOI: 10.22587/ajbas.2022.16.12.1
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Study of the Ecological Interest of a Rice Husk Ash Mortar
Abbas Tiambo DATCHOSSA1, Valéry K. DOKO2, Kocouvi Agapi HOUANOU3, Emmanul E.T. OLODO4
ABSTRACT: To comply with the requirements of sustainable development, several organizations are studying the possibility of using renewable and ecological materials. This work aims to determine in what context it is ecological to replace cement with rice husk ash partially. To do this, on the one hand, we determined the CO2 mass emitted during the production of cement from the limestone decarbonation equation. On the other hand, we determined the CO2 mass emitted during the production of RHA (rice husk ash) using the complete rice husk combustion equation and Steven's realistic decomposition model. We then compared the quantity of CO2 emitted during the production of cement to that emitted during the combustion of the rice husk. Finally, we partially replaced cement with ground RHA to evaluate the effect of this substitution on the porosity and compressive strength of mortars. According to the findings of this study, cement production emits 0.94 kg of CO2 per kilogram of clinker, compared to 1.72 kg for RHA production, per kilogram of clinker and per kilogram of RHA, respectively. Also, these results show that using RHA leads to an improvement of the porosity up to 10.14%, and 15.59% for the improvement of the compressive strength. It is, therefore not more ecological to produce rice husk ash and replace it with cement. However, using rice husk ashes from energy production furnaces has a double advantage. The first concerns the environmental aspect, and the second concerns the improvement of mortars' durability and compressive strength.
[ FULL TEXT PDF 8-16 ] DOI: 10.22587/ajbas.2022.16.12.2
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A note on the Intra-Capsular Development of Neritina turrita Gmelin 1791
Kroum K. Hristov
ABSTRACT: Background: Neritina turrita Gmelin 1791 is an amphidromous gastropod mollusk found in the tropical coastal swamps. They are popular in the ornamental fish trade, and not successfully bred in captivity. Objective: The work aims to optimise a monitoring protocol for the early stages of N. turrita development in artificial habitat. Method: Long-term observations of N. turrita egg capsules in 5 g/L saline-water at 25oC. Results: 6 observable steps were identified, namely: i) deposition; ii) sinking of the developing embryos after 5 days; iii) movement of the developing trochophores after 9-17 days; iv) growth - packing the limited space of the capsule (18-24 days); v) darkening after the 25th day; and vi) hatching. Viable veligers are produced after day 33, however signs of cachexia due to undernourishment are noticeable between days 84-107. Subsequently, no live veligers were present. The approximate veliger size (length ~ 165-176 um and diameter of ~ 110-122 um), volume (~ 0.0010-0.0014 mm3) and relative density (> 1.3471 g/cm3) were determined, suggesting a possible buoyant depth of ~300 m. Conclusions: 1) N. turrita can be maintained and reproduce in artificial conditions. 2) The monitoring steps of the observable egg capsule changes determined, and related to the morphology of the developing embryo. 3) During their migratory journeys in the ocean they travel on the edge of the photic zone (200 m) or bellow, in the dysphotic zone, where photosynthesis is very limited or not possible, restricting N. turrita veligers’ diet to bacterias, fungi and decaying organic matter.
[ FULL TEXT PDF 17-21 ] 10.22587/ajbas.2022.16.12.3
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