نتایج جستجو برای: ionization
تعداد نتایج: 38104 فیلتر نتایج به سال:
change of the tautomeric preference for radical cation of pyruvic acid. dft studies in the gas phase
keto-enol tautomerism was investigated for ionized pyruvic acid using the dft(b3lyp) method and the larger basis sets [6-31++g(d,p), 6-311++g(3df, 3pd) and aug-cc-pvdz]. change of the tautomeric preference was observed when going from the neutral to ionized tautomeric mixture. ionization favors the enolization process (ketoenol) of pyruvic acid, whereas the ketonization (ketoenol) is preferred ...
a time-of-flight mass spectrometer (tof-ms) developed in our laboratory at isfahan university of technology is described here. the tof-ms instrument uses laser as the ionization source which provides an opportunity to investigate the ions formed in laser ablation or desorption. the tof-ms has an ionization chamber containing an accelerator and an ion lens to focus the ions into a one meter line...
Background and purpose: Protein binding (PB) is an important pharmacokinetic parameter in drug discovery and development. In past years Abraham parameters were used to predict some physicochemical and pharmacokinetic properties of drugs. But in these cases, the ionization of drugs in blood pH (7.4) was ignored. Recently, Abraham parameters of chemical compounds in ionized form are proposed. Als...
According to International Atomic Energy Agency (IAEA) recommendations, the calibration of ionization chambers used for radiotherapy dosimetry follows the substitution method which demands the use of a reference ionization chamber. This work introduces the Design and fabrication of cylindrical ionization chamber for dosimetry to be used by standard dosimetry laboratories. The result of the qual...
The ability of the present semiempirical quantum mechanics methods are surveyed for reproducing the transannular interaction in the bifunctional N-phenyl-5-azocanones. The AM1 method is the best with the order of reliability being Am1, PM3, MNDO and MINDO/3. AM1 calculations were then carried out for quantification of transannular interaction. The n(o) ionization potential has be...
the term electronegativity .was introduced by linus pauling, who characterized on the basis ofthermodynamic data from the energies of the single bonds. in present study, the density functional theory(dft) was used to calculate electronegativity of atoms. the base of calculation is similar to pauling andmulliken methods. the results indicate that the largest value of electronegativity for fluori...
Change of the tautomeric preference for radical cation of pyruvic acid. DFT studies in the gas phase
Keto-enol tautomerism was investigated for ionized pyruvic acid using the DFT(B3LYP) method and the larger basis sets [6-31++G(d,p), 6-311++G(3df, 3pd) and aug-cc-pVDZ]. Change of the tautomeric preference was observed when going from the neutral to ionized tautomeric mixture. Ionization favors the enolization process (ketoenol) of pyruvic acid, whereas the ketonization (ketoenol) is preferred ...
introduction: delivering maximum dose to tumor and minimum dose to normal tissues is the most important goal in radiotherapy. according to icru, the maximum acceptable uncertainty in the delivered dose compared to the prescribed dose should be lower than 5%, and this is because of the relationship between absorbed dose, tumor control and normal tissue damage. absorbed dose accuracy is investiga...
Paper spray (PS) ionization, an ambient ionization method, has previously been explored as a direct and fast method for mass spectrometric analysis of complex mixtures. It has been applied to the analysis of a wide variety of compounds, mostly small molecules. The work reported here extends the application of PS ionization to noncovalent protein complexes on an ion mobility tandem mass spectrom...
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