Photoelectron angular distribution of the 3s-subshell of atomic aluminum

Hartree-Fock calculations for the photoelectron angular distribution assymmetry parameters β (^1,3P) for the processes Al 3s²3p(²P) + ω → Al⁺ 3s3p(^1,3P) + e^? are carried out neglecting interchannel interactions. While the β's are found to differ from 2, as predicted for open-shell atom s-subshells by Starace, Rast and Manson, the deviations are found to be rather small in Al due to the absence of Cooper minima in the corresponding photoionization cross sections above threshold.     

A comparison study between sodium dodecyl sulfate and sodium dodecyl sulfonate with respect to the thermodynamic properties,micellization, and interaction with poly(ethylene glycol) in aqueous solutions

The density, sound velocity, and conductivity measurements were performed on aqueous solutions of sodium dodecyl sulfate (C₁₂H₂₅SO₄Na) or sodium dodecyl sulfonate (C₁₂H₂₅SO₃Na) in the absence and presence of poly(ethylene glycol) (PEG) at different temperatures. Changes in the apparent molar volumes and isentropic compressibilities upon micellization were derived using a pseudophase-transition approach and the infinite dilution apparent molar properties of the monomer and micellar form of C₁₂H₂₅SO₄Na and C₁₂H₂₅SO₃Na were determined. Variations of the critical micelle concentrations (CMCs) of both surfactants in the solutions investigated with temperature were obtained from which thermodynamic parameters of micellization were estimated. It was found that at low temperature the micelle formation process is endothermic and therefore, this process must be entropically driven. However, upon increasing the temperature, the enthalpic factor becomes more significant and, at temperatures higher than 303.15 K the micellization is enthalpy driven. The interactions between C₁₂H₂₅SO₄Na/C₁₂H₂₅SO₃Na and PEG were studied and it was found that sodium alkyl sulfonates were seen to interact more weakly than their sulfate analogues.     

Investigation of the solvent effect,molecular structure,electronic properties and adsorption mechanism of Tegafur anticancer drug on Graphene nanosheet surface as drug delivery system by molecular dynamics simulation and density functional approach

To understanding the adsorption mechanism and the induced effects of an anticancer drug, Tegafur molecule, on the surface of Graphene nanosheet (GNS) as a drug delivery system, we have performed density functional theory (DFT) and molecular dynamics (MD) methods. DFT calculations give valuable information on the structure, orientation, adsorption energy and charge transfer of nanosheet-molecule in the equilibrium GNS-Tegafur complexes in the gas phase as well as in the aqueous phase, i.e., water. The optimization of GNS-Tegafur geometries shows that drug molecule tends to adsorb via its six-membered aromatic ring to the hexagonal ring of Graphene nanosheet by π–π stacking interaction at the most stable physisorption configuration. Furthermore, the calculated solvation energy (E_sol) represented by a polarizable continuum model show the significant increase in the solubility of GNS after drug adsorption on its surface in the presence of H₂O solvent which leading to the possible applications of GNS in the drug delivery systems. MD simulation is also used to determine the effect of drug concentrations on dynamic properties of Tegafur adsorption on the GNS surfaces in the solution phase. Based on the obtained MD results, it is found that by increasing drug concentration, the van der Waals (vdW) interaction energy becomes more negative and the stabilities of the simulated complexes increase.     

Enhanced Heterotrophic Denitrification: Effect of Dairy Industry Sludge Acclimatization and Operating Conditions

Heterotrophic denitrification of drinking water was enhanced by selection of an anoxic sludge taken from a dairy industry among the sludges taken from various industries, and the effect of carbon sources was examined. Acclimatization to high nitrate concentration was then carried out in a five-stage process. Considering removals of both nitrate and nitrite, the sludge taken from anoxic unit of Tehran Pegah dairy industry was shown to be the superior microbial culture, with ethanol as carbon source as compared to acetate. To enhance the rate of denitrification, acclimatization to nitrate (at 100, 200, 400, 800, and 1,600 mg N-NO₃/L) was carried out in sequencing batch reactors over a 3-month period under anoxic condition, and comparisons were made between the performances of acclimated and non-acclimated sludges at each stage. It was found that acclimatization up to the fourth stage enhanced the specific denitrification rate to a high value of 29.6 mg N-NO₃/h/g mixed liquor suspended solids (MLSS), with no significant nitrite accumulation. Additionally, the effect of initial pH (6, 6.5, 7, and 7.5) and carbon-to-nitrogen (C/N) ratio (1, 1.5, 2, and 3) on the performance of this final acclimated sludge was assessed, where initial pH of 7 and C/N ratio of 1.5 resulted in the best performances considering both nitrate and nitrite removal.     

Synthesis of star-shaped CuO nanoparticles supported on magnetic functionalized graphene: Catalytic and antibacterial activity

In this study, graphene oxide was modified during consecutive functionalization steps with 1,4-diphenylamine, cyanuric chloride, and ethylenediamine. Then, star-shaped CuO nanoparticles were synthesized on modified graphene oxide using the seed-mediated growth method in which nucleation, growth stages, and reduction of graphene oxide to graphene occurred simultaneously. After ensuring successful synthesis of CuO nanoparticles and to facilitate recycling, a magnetization process was utilized by adding iron oxide nanoparticles. This nanocomposite was characterized by transmission electron microscopy, X-ray powder diffraction, scanning electron microscopy, and Fourier transform infrared spectroscopy. The prepared heterogeneous catalyst was investigated for the reduction of organic dyes in the presence of NaBH₄ as a reducing reagent. The kinetic data obtained for the reduction of methyl orange (MO), methylene blue (MB), 4-nitrophenol (4-NP), and rhodamine 6G (Rh6G) were fitted to first-order rate equations, and the calculated rate constants for the reduction of MO, MB, 4-NP and Rh6G were as follows: −0.091, −0.071, −0.045, and 0.040, respectively. As star-shaped CuO nanoparticles showed a higher antibacterial effect compared to spherical-shaped CuO nanoparticles, the antibacterial activity of star-shaped CuO nanoparticles immobilized on magnetic functionalized graphene was evaluated against Gram-positive and Gram-negative bacteria through an agar well diffusion assay and demonstrated more antibacterial activity against gram-positive bacteria.     

Analysis of the structures,energetics, and vibrational frequencies for the hydrogen-bonded interaction of nucleic acid bases with Carmustine pharmaceutical agent: a detailed computational approach

In the present study, it is attempted to scrutinize the hydrogen bonding interaction between Carmustine drug and DNA pyrimidine bases by means of density functional theory calculations regarding their geometries, binding energies, vibrational frequencies, and topological features of the electron density in the gas phase and the water solution. Based on the density functional theory results, it is found that the process of intermolecular interaction between Carmustine drug and nucleobases is exothermic and all of the optimized configurations are stable. Furthermore, the negative stability energy represented by a polarizable continuum model shows the significant increase in the solubility of the nucleobase after hydrogen bonding intermolecular interaction in the presence of water solvent. It is also found that the intermolecular hydrogen bonds between drug and the nucleobases play the significant role in the stability of the physisorption configurations. Hydrogen bond energies for hydrogen-bonded complexes are obtained from Espinosa method and the atoms-in-molecules theory are also applied to get a more precise insight into the nature of the intermolecular hydrogen bond interactions.     

Phytotherapeutic inhibition of supragingival dental plaque

Antimicrobial activities and biofilm-formation preventive properties of Mentha piperita and Cuminum cyminum essential oils and chlorhexidine were assessed against Streptococcus mutans and Streptococcus pyogenes. Gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS) analysis led to the identification of 26 and 32 compounds in the essential oils of M. piperita and C. cyminum, respectively. Minimal bactericidal concentrations (MBC) of the oils and chlorhexidine and microbial decimal reduction time (D value) were determined. Antibacterial and in vivo biofilm preventive efficacies of all the concentrations of M. piperita oil were significantly (p<0.001) higher. The biofilm inhibitory properties in planktonic cultures were in M. piperita > chlorhexidine > C. cyminum order. In vivo experiments conducted on male and female volunteers who brushed with essential oil blended toothpastes indicated that lower concentrations of the oils, in particular the M. piperita oil, were significantly higher (p<0.001) and effective during the course of the study as compared to chlorhexidine. In conclusion, there may be a potential role for essential oils in the development of novel anticaries treatments.     

Synthesis and characterization of Ni(II) complex functionalized silica-based magnetic nanocatalyst and its application in C–N and C–C cross-coupling reactions

Molecular Diversity - A new magnetically recoverable silica-based nickel(II) nanocatalyst was synthesized by a simple cost-effective procedure, which was characterized by TEM, SEM, XRD, VSM...     

Determination of trace elements in blood samples of patients affected by multiple sclerosis from Iran by neutron activation analysis

Multiple sclerosis (MS) is a neurological autoimmune disease in which the immune system attacks the central nervous system for unknown reasons and causes several damages to human body by demyelinating the nerve cells. One of the possible cause of this disease is the abnormality levels of some trace elements such as Br, Fe, Rb, Sb, As, and Zn in human body. This study attempts to measure the levels of four trace elements of Br, Fe, Rb, and Zn in the patients?? blood samples and compare them with control samples from healthy individuals. It should be noted that the objectives set out partly met. According to the obtained results, the differences between the levels of Br, Fe, and Rb in patients?? blood samples and control was not significant (P?>?0.05). However, the average level of Zn between samples and controls showed a significant difference (P?<?0.05). Therefore the lower level of Zn in blood is likely to be a major cause of MS emergence. Furthermore, by using the concentration level of Zn as indicator, it was revealed that the risk of MS infection rises as the number of pregnancies increase.