نتایج جستجو برای: activation enthalpy
تعداد نتایج: 433132 فیلتر نتایج به سال:
We derive exact expressions for the local entanglement entropy epsilon in the ground state of the one-dimensional Hubbard model at a quantum phase transition driven by a change in magnetic field h or chemical potential mu. The leading divergences of delta epsilon/delta h and delta epsilon/delta mu are shown to be directly related to those of the zero-temperature spin and charge susceptibilities...
A study of the influence of the moisture and the grain size on the gelatinization temperature (Tp1) of starch from four industrial maize flours as well as an unprocessed maize sample is presented. The gelatinization is a phase transition that can be observed using Differential Scanning Calorimetry (DSC), and it is manifest as an endothermic peak in the DSC thermogram. Results show that for 60, ...
Butters, margarines and table spreads are water-in-oil emulsions. Melting characteristics of these products are important for flavor release and consumer acceptance. One characteristic that is believed to discriminate butters from margarines is a cooling sensation perceived in-mouth while consuming these products. Here, we investigated different methods to characterize sensorically and analytic...
To determine the effectiveness of the ribosome as a catalyst, we compared the rate of uncatalyzed peptide bond formation, by the reaction of the ethylene glycol ester of N-formylglycine with Tris(hydroxymethyl)aminomethane, with the rate of peptidyl transfer by the ribosome. Activation parameters were also determined for both reactions, from the temperature dependence of their second-order rate...
Kinetics of solid state stability of seven derivatives of 3,5-disubstituted tetrahydro-2H-1,3,5-thiadiazine-2-thione (THTT) of glycine as a model for amino acids and peptide drugs were studied using differential scanning calorimetry (DSC). Each DSC curve for each derivative showed an endothermic peak followed by an exothermic one, which could be attributed to the melting and decomposition, resp...
The intensity of tropical cyclones is sensitive to the rates at which enthalpy and momentum are transferred between sea and air in the high-wind core of the storm. Present models of the wind dependence of these transfer rates suggest that the effective drag coefficient is more than twice the effective enthalpy transfer coefficient at wind speeds above 25 m s21. Using this ratio in numerical mod...
in this study at first , an azo dye, 2,7- naphthalenediol, 2-[(4-bromophenyl)azo (bpand) as a ligand has been synthesized by addition of p-bromoaniline to the modified montomorillonite k10 clay. this ligand was characterized using 1h-nmr, uv-vis and ir spectroscopies. subsequently, its interaction with calf thymus deoxyribonucleicacid ,ct-dna was investigated in 5 mm phosphate buffer solution, ...
The enthalpy of hydrolysis of the 3’-bond of several cyclic 3’,5’-nucleotides and of the 2’-bond of several cyclic 2’,3’nucleotides has been measured calorimetrically. In each case, the enthalpy was indicative of a high energy bond, although values for different compounds varied from -7.7 to 14.1 kcal mole-‘. The enthalpy of hydrolysis of the cyclic 3’,5’-nucleotides, but not that of the cyclic...
Constitutive equations are derived for enthalpy recovery in polymeric glasses after thermal jumps. The model is based on the theory of cooperative relaxation in a version of the trapping concept. It is demonstrated that some critical temperature Tcr and some critical degree of crystallinity fcr exist in a semicrystalline polymer above which the energy landscape becomes homogeneous and structura...
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