A set of chemical reactions is proposed to account for the formation of pantothenic acid derivatives from a primeval atmosphere composed of ammonia, formaldehyde, propyne, ethyne, hydrogen sulfide, hydrogen and water. Three precursor molecules are initially formed; a di-adduct of propyne and the catalyst Mg.porphin, azetidine2one, and 2-amino ethyl mercaptan. These then react sequentially to fo...

In this study Klason lignins from Eucalyptus grandis (LEUG) and Pinus taeda (LPIT) were characterized using Fourier transform infrared (FTIR) spectroscopy and thermogravimetry (TGA). The degradation kinetic parameters were determined by TGA using the Kissinger method. Thermogravimetric results showed that LPIT had higher thermal stability and also higher activation energy than LEUG. FTIR result...

abstract the aim of this research was to investigate the enthalpy variations of iranian flat breads during storage in room temperature and determining relationship between enthalpy and amount of staling development. for this purpose, the major iranian breads including barbari, taftoon, lavash and sangak beside baguette, were prepared using standard ingredients, specific recipe, and under contro...

During cellulose dissolution in non-derivatizing solvents, the interand intramolecular hydrogen bonds of the polymer are deconstructed. This occurs either by hydrogen bond formation between one or more components of the solvent systems and the hydroxyl groups of the cellulose or by coordination bond formation between the metal ion present in the medium and the hydroxyl group of cellulose molecu...

The hydrogen solubility in zirconia (yttria stabilized zirconia, YSZ) using a tritium imaging plate (IP) technique has been measured in a temperature region ranging from 673K to 973K. The tritium distribution in the zirconia specimens was nearly uniform suggesting an equilibrated dissolution. The hydrogen solubility in specimens were rather low (around ppm or below) and showed Arrhenius type te...

Antioxidants are compounds which can prevent biological and chemical substances from oxidative damage by reactive oxygen species. Flavonoids are the most important class of polyphenolic compounds that because of their antioxidant characters possess biological activities and pharmacological effects. Chrysin-6-C-fucopyranoside and chrysin-3-malonyl-6-C-fucopyranoside are mono C-glycosyl derivativ...

We have synthesized a new metastable metal hydride with promising hydrogen storage properties. Body centered cubic (bcc) magnesium niobium hydride (Mg(0.75)Nb(0.25))H(2) possesses 4.5 wt% hydrogen gravimetric density, with 4 wt% being reversible. Volumetric hydrogen absorption measurements yield an enthalpy of hydride formation of -53 kJ mol(-1) H(2), which indicates a significant thermodynamic...