Patient skin dose measurement and risk of deterministic effect during fluoroscopy cardiac procedures.

This study aimed at assessing patient's peak skin doses (PSD) during fluoroscopy cardiac procedures and proposed a look up table to enhance patient's dose management. Perspex phantom and thermoluminescent dosemeters (TLD) were irradiated for different dose levels with X-ray equipment (Philips Azurion 7). It was found that PSD measures were higher than the kerma at the interventional reference point [K (IRP)] reported with factors 1.55, 1.75 and 2.88 for anterior posterior (AP0o), left anterior oblique (LAO45o) and right anterior oblique (RAO45o), respectively. The equations describing the correlation between the PSD measured kerma area product and cumulative air kerma were found with R-square values of 0.98 and 0.99, respectively. The statistical analysis shows a strong linear correlation between PSD and K (IRP) (P-value = 0.05). It was also found that 27% of the patients population considered in this work, received a skin dose higher than the threshold of deterministic effect of 2 Gy and a look up table with the equation of fitness were proposed to be implemented in the facility for K (IRP) higher than 500 mGy.

Theoretical investigation of the atmospheric implication for the reaction of •OH radical with CF2C(CH3)-CX3, X = H, F.

The atmospheric implication of the hydrofluoroolefines (HFO) CF2C(CH3)-CX3, X=(H,F), through the reactions with •OH radical were assessed using the M06-2X/6-311++G(df,p)//6-31+G(df,p) method. The rate coefficient was calculated over the temperature range 200-500 K, and was accurately expressed in non-Arrhenius form exp(a+bT-1+cT-2) cm3molecule-1s-1, where a, b, and c are real constants. This served to estimate the atmospheric lifetime along with the photochemical ozone creation potential (POCP), which yielded lifetimes of 0.39 and 3.53 days and POCPs of 51.00 and 3.57 for X = H and F, respectively. The radiative forcing efficiencies (RFEs) were also estimated at G96LYP/6-311G(df,p) along with the global warming potentials (GWPs). The results showed negligible impact towards global warming for the HFOs.

Temperature-dependent oxidation of BSCAPE molecule in methanol medium.

Temperature-dependent solvation free energy and oxidation by free energy of ionization of 2-Phenylethyl (2E)-3-(1-benzenesulfonyl-4,5-dihydroxyphenyl) acrylate (BSCAPE) in methanol medium are the concerns of the present work. This molecule is a relevant phenolic acid enclosing multiple bioactivities. The explicit, implicit and discrete-continuum models of solvation were used. The methanol molecules were coordinated to this acid to form cluster complexes. The dual method M06-2X/6-31++G(d,p)//B3LYP/6-31G(d) was employed along with basis set superposition error correction. The results show that, the free energy of coordination and solvation are distant. Both quantities increase with temperature. From discrete-continuum treatment, there is non-spontaneity of solvation process, while coordination yielded spontaneity and non-spontaneity at cold and hot room temperatures, respectively. The ionization potential in gas phase, decreases with temperature. All the solvation models yielded lower ionization potential than that of gas phase. Thus, it follows that, the increase of temperature and methanol medium favours the oxidation of BSCAPE. Consequently, this favours its metabolism processes.

Insight of UV-vis spectra and atmospheric implication for the reaction of ˙OH radical towards glyphosate herbicide and its hydrates.

The rate constant of the reactions of ˙OH radicals with glyphosate (GPS) and its hydrates (GPS(H2O) n=1-3) were evaluated using the dual method M06-2X/6-311++G(df,p)//6-31+G(df,p) over the temperature range of 200-400 K. The results served to estimate the atmospheric lifetime along with the photochemical ozone creation potential (POCP). The calculations yielded an atmospheric lifetime of 2.34 hours and a POCP of 24.7 for GPS. Upon addition of water molecules, there is an increase of lifetime and decrease of POCP for water monomer and water dimer. The POCP for water trimer is slightly above the gaseous GPS. However, the POCPs of GPS and its hydrates are comparable to that of alkanes. The GPS and its hydrates were found to be a potential reservoir of CO2. The acidification potential (AP) of GPS was found to be 0.189 and decreases upon addition of water molecules. This shows negligible contribution to rain acidification as the AP is less than that of SO2. The UV-vis spectra were attained using the M06-L/6-311++G(3df,3pd) method and cover the range 160-260 nm which fits well with experiment.

Infrared spectra of PEHA molecule and its resistance to oxidation in water and methanol media at 298.15 K: solvent cluster size dependency.

The present work investigates the infrared spectra and solvation free energies (SE) of PEHA ((E)-2-(Pyridin-2-yl) ethyl 3-(3,4-dihydroxyphenyl) acrylate) and their impact on the oxidation. The latter was examined through the ionization potential parameter (IP). These investigations were carried out by the DFT method at B3LYP/6-31G(d) for optimization and frequency calculations and corrected for BSSE. X3LYP/6-311++G(2d,2p) was employed for single-point energy calculations. Water and methanol cluster sizes were used for solvation through the explicit solvent model. Thus, the infrared spectra show that the overview frequencies of PEHA compare well with the experimental results. The intense infrared absorptions of complexes are due to the stretching of O-H bonds of solvent clusters in the range 2600-3850 cm-1. The binding energy per solvent molecule of complexes was calculated and shows that water and methanol clusters mimic the liquid state as from 5 to 10 solvent molecules. The SE of PEHA increases with the increase of the cluster size of water and methanol in the direction of the limit. The latter was censured by the solvation done using the combined explicit-implicit solvent model. As for IP parameter, the results are largely above the IP limit and lower than the IP from gas phase. Thus, water and methanol media have an effect of lowering the IP of PEHA compound. Consequently, both media favour the oxidation of PEHA molecule, which facilitates its metabolism in human organism.

DFT Study of Photochemical Properties and Radiative Forcing Efficiency Features of the Stereoisomers cis- and trans-CHCl═CH-CF3.

The accurate assessment of radiative forcing efficiency (RFE) of a greenhouse gas is based on the precise knowledge of its structure and infrared absorption spectrum. The present work investigates the UV-vis absorption spectra and IR absorption spectra that are used for the determination of RFE of the short-lived compounds, cis- and trans-CHCl═CHCF3 (CTFP). These investigations were carried out with six different density functional theory (DFT) methods B3LYP, CAM-B3LYP, M06, M06-2X, TPSS0, and ωB97X-D associated to the basis set 6-31G(3df). Therefrom, the relative populations of the two states cis and trans for temperatures over the range 220-370 K at 1 atm and along the atmospheric altitude were assessed. It turns out that trans-CTFP is the abundant component between the two states. This review reveals that B3LYP and M06 reproduce well the experimental results of UV-vis spectra of trans-CTFP. As for cis-CTFP, EOM-CCSD is not well fitted by DFT methods. The cis- to trans-CTFP isomerization leads to the red shift for DFT methods and to the blue shift in regard to EOM-CCSD and experimental results. The IR absorption spectra are well fitted by B3LYP over the range 500-1600 cm-1 and TPSS0 over 1300-2000 cm-1 for both stereoisomers. Moreover, the root-mean-square errors (RMSEs) of frequencies from experimental data are lower for B3LYP and TPSS0 for both systems. The computed IR absorption band strengths over 500-2000 cm-1 for cis- and over 600-1800 cm-1 for trans-CTFP are consistent with the experiment. The relevant descriptor RFEs of the climate effect were calculated using a narrow band model for a constant vertical profile and then corrected with a lifetime factor for different computational methods. The computed values correlate well with the experimental results for both stereoisomers except M06-2X and TPSS0. It is worth noting that, for both systems, the intense radiative forcing spectra are located at frequencies ranging in 1000-1200 cm-1. The lower forcings of trans-CTFP lying in the atmospheric window region 800-1000 cm-1 are greater than those of cis-CTFP. Therefore, RFE(trans-CTFP) = 1.127 RFE(cis-CTFP).

Thermodynamic of solvation, solute - Solvent electron transfer and ionization potential of BSCAPE molecule and its UV-vis spectra in aqueous solution.

The molecular system 2-Phenylethyl (2E)-3-(1-benzenesulfonyl-4,5-dihydroxyphenyl) acrylate (BSCAPE) is a phenolic acid that covers a large spectrum of biological properties. The investigations of solvation and oxidation processes of BSCAPE molecule by computational means were the challenge of this present work. Water was required for solvation throughout the work. The explicit H2O were sequentially added to form the complexes BSCAPE(H2O)n=0-11. The discrete - continuum model was at the heart of this work. DFT and TD-DFT both associated to the continuum model SMD were required. Hence, the structures, the solvation energies, the energies of solute - solvent electron transfer (SSET), the ionisation potential (IP), and the UV-vis spectra were studied. It comes out that, the structure of the CAPE part included in BSCAPE agrees well with the available experimental values of CAPE but with a minor influence due to the presence of benzensulfonyl group. The enthalpy and free energy of solvation increase linearly with nH2O. The global reactivity indexes were assessed to appreciate the oxidation of BSCAPE. The latter quality was strongly assessed by the enthalpy and free energy of SSET and IP. The SSET potential increase with nH2O and the size of water clusters. The values 723.16 and 711.62 kJ/mol were found for enthalpy and free energy of IP respectively. Then in aqueous solution, the results fall down and upon addition of nH2O, they approach gas phase value for 11H2O and still are not stabilized. Therefore, the resistance to oxidation starts to raise at this level. Elsewhere, the UV-vis spectra of BSCAPE present four important peaks about 279.3, 234.8, 208.4 and 199.4 nm in gaseous state. The excitation shifts to the red as the number of H2O increase. Their oscillator strengths also increase with solvation.

Structure, antioxidative potency and potential scavenging of OH and OOH of phenylethyl-3,4-dihydroxyhydrocinnamate in protic and aprotic media: DFT study.

DFT methods including B3LYP, B3PW91 and M05-2x associated to 6-31+G(d,p) were used for the structural and antioxidant potency studies of phenylethyl-3,4-dihydroxy-hydrocinnamate (PDH). Solvents were employed according to their protric and aprotic character. So, calculated structures agree with the experimental data. O4H4 is propitious to scavenge radicals whatever the medium except in water where O3H3 and O4H4 are competitive. The explicit solvents of dichloromethane (DCM) and water present a disparity of OH bond dissociation enthalpy and free energy (BDE and BDFE). These parameters are low in continuum except in water. The ionization potentials (IP) and potential affinities (PA) are low in solvents. BDE, IP and PA are each, approximatively constant in mixed solvent treatment in water using n-H2O (n=3,5,8). Elsewhere, H-atom transfer (HAT) mechanism is favoured in vacuum and DCM, whereas sequential proton loss electron transfer (SPLET) is likely in protic solvents. A discord between HAT and SPLET in benzene is observed. The PDH compound is more antioxidant and resistant to oxidation than caffeic acid phenethyl ester (CAPE). The potential of scavenging of OH and OOH whatever the reaction channel shows that they decay rapidly in any media through HAT. PDH is easily deprotonated in the protic solvents and the resulting product is the most antioxidant and the least resistant to oxidation.

Determination of (226)Ra, (232)Th, (40)K, (235)U and (238)U activity concentration and public dose assessment in soil samples from bauxite core deposits in Western Cameroon.

Determination of activity concentrations in twenty five (25) soil samples collected from various points in bauxite ore deposit in Menoua Division in Western of Cameroon was done using gamma spectrometry based Broad Energy Germanium (BEGe6530) detector. The average terrestrial radionuclides of (40)K, (226)Ra, (232)Th, (235)U and (238)U were measured as 671 ± 272, 125 ± 58, 157 ± 67, 6 ± 3 and 99 ± 69 Bq kg(-1), respectively. The observed activity concentrations of radionuclides were compared with other published values in the world. The outdoor absorbed dose rate in air varied from 96.1 to 321.2 nGy h(-1) with an average of 188.2 ± 59.4 nGy h(-1). The external annual effective dose rate and external hazard index were estimated as 0.23 ± 0.07 mSv year(-1) for outdoor, 0.92 ± 0.29 mSv year(-1) for indoor and 1.13 for the external hazard index, respectively. These radiological safe parameters were relatively higher than the recommended safe limits of UNSCEAR. Consequently, using of soil as building material might lead to an increase the external exposure to natural radioactivity and future applications research need to be conducted to have a global view of radioactivity level in the area before any undergoing bauxite ore exploitation.

DFT study of the effect of solvent on the H-atom transfer involved in the scavenging of the free radicals (·)HO2 and (·)O2(-) by caffeic acid phenethyl ester and some of its derivatives.

H-atom transfer from caffeic acid phenethyl ester (CAPE), MBC (3-methyl-2-butenyl caffeate), BC (benzoic caffeate), P3HC (phenethyl-3-hydroxycinnamate), and P4HC (phenethyl-4-hydroxycinnamate) to the selected free radicals (·)HO2 and (·)O2(-) was studied. Such a transfer can proceed in three different ways: concerted proton-coupled electron transfer (CPCET), electron transfer followed by proton transfer (ET-PT), and proton transfer followed by electron transfer (PT-ET). The latter pathway is sometimes competitive with SPLET (sequential proton loss electron transfer) in polar media. Analyzing the thermodynamic descriptors of the reactions of CAPE and its derivatives with co-reactive species-in particular, the free energies of reactions, the activation barrier to the CPCET mechanism, and their rate constants-appears to be the most realistic method of investigating the H-atom transfers of interest. These analyses were performed via DFT calculations, which agree well with the data acquired from experimental studies (IC50) and from CBS calculations. The CPCM solvation model was used throughout the work, while the SMD model-employed as a reference-was used only for CAPE. The main conclusion drawn from the analysis was that SPLET is the mechanism that governs the reaction of phenolic acids with (·)HO2, while PT-ET governs the reaction of phenols with (·)O2(-). In kinetic investigations of the CPCET process, the rate constant decreases as the solvent polarity increases, so the reaction velocity slows down.

Structures of protonated methanol clusters and temperature effects.

The accurate evaluation of pKa's, or solvation energies of the proton in methanol at a given temperature is subject to the determination of the most favored structures of various isomers of protonated (H(+)(MeOH)n) and neutral ((MeOH)n) methanol clusters in the gas phase and in methanol at that temperature. Solvation energies of the proton in a given medium, at a given temperature may help in the determination of proton affinities and proton dissociation energies related to the deprotonation process in that medium and at that temperature. pKa's are related to numerous properties of drugs. In this work, we were interested in the determination of the most favored structures of various isomers of protonated methanol clusters in the gas phase and in methanol, at a given temperature. For this aim, the M062X/6-31++G(d,p) and B3LYP/6-31++G(d,p) levels of theory were used to perform geometries optimizations and frequency calculations on various isomers of (H(+)(MeOH)n) in both phases. Thermal effects were retrieved using our homemade FORTRAN code. Thus, we accessed the relative populations of various isomers of protonated methanol clusters, in both phases for temperatures ranging from 0 to 400 K. As results, in the gas phase, linear structures are entropically more favorable at high temperatures, while more compact ones are energetically more favorable at lower temperatures. The trend is somewhat different when bulk effects are taken into account. At high temperatures, the linear structure only dominates the population for n ≤ 6, while it is dominated by the cyclic structure for larger cluster sizes. At lower temperatures, compact structures still dominate the population, but with an order different from the one established in the gas phase. Hence, temperature effects dominate solvent effects in small cluster sizes (n ≤ 6), while the reverse trend is noted for larger cluster sizes.

Solvation Energies of the Proton in Methanol.

pKa's, proton affinities, and proton dissociation free energies characterize numerous properties of drugs and the antioxidant activity of some chemical compounds. Even with a higher computational level of theory, the uncertainty in the proton solvation free energy limits the accuracy of these parameters. We investigated the thermochemistry of the solvation of the proton in methanol within the cluster-continuum model. The scheme used involves up to nine explicit methanol molecules, using the IEF-PCM and the strategy based on thermodynamic cycles. All computations were performed at B3LYP/6-31++G(dp) and M062X/6-31++G(dp) levels of theory. It comes out from our calculations that the functional M062X is better than B3LYP, on the evaluation of gas phase clustering energies of protonated methanol clusters, per methanol stabilization of neutral methanol clusters and solvation energies of the proton in methanol. The solvation free energy and enthalpy of the proton in methanol were obtained after converging the partial solvation free energy of the proton in methanol and the clustering free energy of protonated methanol clusters, as the cluster size increases. Finally, the recommended values for the solvation free energy and enthalpy of the proton in methanol are -257 and -252 kcal/mol, respectively.