the armaticity of 5 methylcytosine tautomers in the gas phase has been studied and the chemical structures of related tautomers are investigated . the electronic energy, enthalpy and free energy of each tautomer are also estimated at the b3lyp/6-31 g* // b3lyp/6-31 g* and mp2 / 6-31 g* // mp2 / 6-31 g* levels

In this study, the first and the second laws of thermodynamics (exergetic analysis) are used to analyse the performance of a single stage ammonia-water absorption cooling system operating under different working conditions. In this analysis, the performance of the system is simulated under various operating temperatures: the condenser and absorber (30 and 40°C), evaporator (-10°C, 0°C and +10°C...

The liquid-phase enthalpy of mixing for Al–Tb alloys is measured for 3, 5, 8, 10, and 20 at% Tb at selected temperatures in the range from 1364 to 1439 K. Methods include isothermal solution calorimetry and isoperibolic electromagnetic levitation drop calorimetry. Mixing enthalpy is determined relative to the unmixed pure (Al and Tb) components. The required formation enthalpy for the Al3Tb pha...

Solid dispersions of artemether and polyethylene glycol 6000 (PEG6000) were prepared in ratio 12 : 88 (group-1). Self-emulsified solid dispersions of artemether were prepared by using polyethylene glycol 6000, Cremophor-A25, olive oil, Transcutol, and hydroxypropyl methylcellulose (HPMC) in ratio 12 : 75 : 5 : 4 : 2 : 2, respectively (group-2). In third group, only Cremophor-A25 was replaced wi...

The unfolding enthalpy of the pH 4 molten globule from sperm whale apomyoglobin has been measured by isothermal titration calorimetry, using titration to acid pH. The unfolding enthalpy is close to zero at 20 degrees C, in contrast both to the positive values expected for peptide helices and the negative values reported for holomyoglobin and native apomyoglobin. At 20 degrees C, the hydrophobic...

The temperature dependence of thermodynamic quantities, such as heat capacity, entropy and free enthalpy, may be obtained by using well-known equations that relate these quantities to the enthalpy of the molecular system of interest at a range of temperatures. In turn, the enthalpy of a molecular system can be estimated from molecular dynamics simulations of an appropriate model. To demonstrate...

Enthalpy (fuel mass fraction and/or temperature) fluctuations in the oncoming mixture are known to have important impacts on premixed combustion and in particular on combustion instability. Theoretical modeling has primarily been following an empirical approach. In Part I of the present study, an asymptotically reduced first-principle theory was derived from the reactive Navier-Stokes equations...

The standard enthalpy of formation and the enthalpy of sublimation of crystalline 2-hydroxyphenazine-di-N-oxide, at T = 298.15 K, were determined from isoperibol static bomb combustion calorimetry and from Knudsen effusion experiments, as -76.7 +/- 4.2 kJ.mol(-1) and 197 +/- 5 kJ.mol(-1), respectively. The sum of these two quantities gives the standard enthalpy of formation in the gas-phase for...

It has long been conjectured that spray ejected from the high-wind ocean surface enhances air/sea enthalpy fluxes, but a lack of observational data, particularly at wind speeds exceeding 20 m s−1, has prevented either confirmation or refutation of this hypothesis. The current study has two aims: first, to provide an estimate of surface enthalpy fluxes obtained from dropsonde data and second, to...