Conversion of hydrocarbon gases in dielectric barrier discharge in the presence of water

The conversion of C₁–C₄ hydrocarbons into gaseous and liquid products in a dielectric barrier discharge plasma in the presence of water has been studied. The formation of a deposit on the electrode surface is prevented by introducing water in the liquid state into a gaseous hydrocarbon stream, a finding that has been confirmed by IR spectroscopic study of the electrode surface. Hydrogen and C₂₊ hydrocarbons have been detected among the gaseous products of conversion, the liquid products being represented by C₆–C₁₀₊ alkanes. The total liquid products have amounted to 13.4, 26.0, or 36.6% for the methane, propane, or n-butane conversion, respectively. A 10% propane or butane admixture to methane increases the yield of the liquid products to make 22.0 and 31.7% for the methane–propane and the methane–butane mixture, respectively.     

Complex-forming and ion-selective properties of bis(2-diphenylphosphorylalkyl)phenyl ethers of ethylene glycols. Crystal structures of cadmium complexes

New complexes of cadmium iodide with 1,3-bis[2-(diphenylphosphoryl)phenoxy]propane [CdL⁰I₂], 1,2-bis[2-(diphenylphosphorylethyl)phenoxy]ethane [CdL^{1, 2}I₂], and 1,8-bis[2-(diphenylphosphorylethyl) phenoxy]-3,6-dioxaoctane [CdL^{3, 2}I₂] are synthesized and their IR spectra and crystal structures are studied. Electroanalytical characteristics of membranes of ion-selective electrodes based on L⁰, L^{1, 2}, L^{3, 2}, and known crown ethers are compared for cations of alkali, alkaline-earth, and transition metals. Ligand L^{3, 2} is the first podand with terminal diphenylphosphoryl fragments to exhibit selectivity with respect to the cadmium cation.     

Effect of dielectric medium on angiotensin converting enzyme inhibitors binding to Zn<Superscript>2+</Superscript>

The Becke3LYP density functional was used to study structural and thermodynamic parameters of bivalent zinc cation complexes with selected substrates and ACE inhibitors (H₂O/OH⁻, neutral forms of captopril, zofenoprilat, omapatrilat, CH₃CONHCH₃, and N-terminal anions of captopril, zofenoprilat, omapatrilat, enalaprilat, perindoprilat, trandolaprilat, and fosinoprilat). The combination of DFT and the conductor-like polarizable continuum model (CPCM) were employed to compute the Gibbs interaction energies (ΔG) between Zn²⁺ and the selected ACE inhibitors for dielectric media with ɛ = 5 (to simulate the protein environment) and for water media (ɛ = 78.39) for comparison purposes. The results show that ΔG is sensitive to the dielectric constant of the environment and that lower dielectric medium favors the binding of inhibitors to the zinc cation.     

Mechanical properties of silica hydrogels prepared and aged at physiological conditions: testing in the compression mode

The mechanical properties for silica hydrogel prepared at physiological conditions are reported in this paper. The mechanical testing was performed in the compression mode determining the mechanical characteristics as a function of aging time in TRIS buffer up to 14 days. In addition to a typically used gradient method for Young’s modulus determination from the stress–strain curves, a new phenomenological model was proposed to describe the experimental data. The mechanical properties were stabilized after 2 days of aging, which was concluded from an increase in Young’s modulus between 90 and 400 kPa, an increase in stress at break between 50 and 100 kPa and by a decrease in relative deformation at break from 0.26 to 0.16. The height of samples was constant in the first three days of aging followed by a decrease by ~20%. Dissolving of silica hydrogel characterized through determination of silica content in TRIS buffer employing the molybdenum method was not found to be responsible for this phenomenon. The phenomenological model is proposed to be used for a reliable evaluation of mechanical properties of silica as well as other hydrogels exhibiting low Young’s modulus.     

Effect of methanol on the dissolution of neodymium oxide in hydrochloric acid solutions

The effect of methanol on the solubility of Nd₂O₃ in HCl medium in the temperature range of 25–55°C were studied. HCl-CH₃OH was observed to be a better solvent than HCl-CH₃OH-H₂O and hydrochloric acid for the dissolution of Nd₂O₃ mainly due to prevention of neodymium hydroxide and dissolution increased with increase of HCl concentration even at high HCl concentrations. Presence of methanol in the medium was determined to cause corresponding decreases in conductivity, E_SCE, pH values with corresponding increase in E_R values. Neodymium compounds formed in HCl-CH₃OH medium at 25°C were isolated and identified using X-ray diffraction, thermal and chemical analysis methods and their thermal behaviour were investigated between 25–1100°C. NdCl₃ × x ₁CH₃OH and NdCl₃ × x ₂CH₃OH × 4.14H₂O (x ₁ + x ₂ = 2.8) were formed in non-aqueous medium and these compounds were converted into NdCl₃, NdCl_2.37 and NdCl₃ × 0.47CH₃OH with complete and partial loss of water and methanol around 240°C respectively. Methanol was completely removed around 390°C with formation of NdCl_2.37 (77.5%) and NdOCl (22.5%) and NdOCl was detected as the major stable phase above 700°C.     

Down-regulation of Bcl-2 and Akt induced by combination of photoactivated hypericin and genistein in human breast cancer cells

Presented experiment considers combination of genistein and photodynamic therapy with hypericin with a view to achieve higher therapeutic outcome in human breast adenocarcinoma cell lines MCF-7 and MDA-MB-231, both identified in our conditions as photodynamic therapy resistant. Since genistein is known to suppress Bcl-2 expression, we predicted that photodynamic therapy with hypericin might benefit from mutual therapeutic combination. In line with our expectations, combined treatment led to down-regulation of Bcl-2 and up-regulation of Bax in both cell lines as well as to suppression of Akt and Erk1/2 phosphorylation induced by photoactivated hypericin in MCF-7 cells. Although Akt and Erk1/2 phosphorylation was not stimulated by photodynamic therapy with hypericin in MDA-MB-231 cells, it was effectively suppressed in combination. Variations in cell death signaling favoring apoptosis were indeed accompanied by cell cycle arrest in G₂/M-phase, activation of caspase-7, PARP cleavage and increased occurrence of cells with apoptotic morphology of nucleus. All these events corresponded with suppression of proliferation and significantly lowered clonogenic ability of treated cells. In conclusion, our results indicate that pre-treatment with tyrosine kinase inhibitor genistein may significantly improve the effectiveness of photodynamic therapy with hypericin in MCF-7 and MDA-MB-231 breast cancer cells.     

Degradation of HER2 Receptor Through Hypericin-mediated Photodynamic Therapy

Current treatment of breast cancer is often affected by resistance to therapeutics, for which the human epidermal growth factor receptor 2 (HER2) may be responsible. Here, we report for the first time the use of hypericin-mediated photodynamic therapy (HY-PDT) in combination with a selective HER2 inhibitor (AG 825) on SKBR-3, a HER2 overexpressing human breast adenocarcinoma cell line. The results demonstrate that HY-PDT is able to degrade HER2 with an impact on its signaling cascade. Combination with AG 825 resulted in increased apoptosis induction, total degradation of HER2 and inhibition of colony formation. Downregulation of HSP90, Mcl-1, Bcl-xL and upregulation of Bax was also observed. This knowledge provides the basis for the possible application of HY-PDT in preclinical and clinical models of breast cancer treatment.     

Estimation of the possibility of internal solid-phase reactions to occur in some oxide systems

We calculated the energy of defect formation and the mobility of defects in cubic ZrO₂-based solid solutions and in nickel and cadmium oxides in a view of developing methods for controlling internal solidphase reacitons in an inert matrix, these reactions being of considerable importance for manufacturing matrix/inclusion composites. The calculations were carried out for an ionic model of chemical bond using GULP software. The frequency factors in the Arrhenius temperature funcitons of diffusion coefficients were estimated for various cationic and anionic defects using circular vibration frequencies of hopping atoms. A frequency factor was estimated as the mean vibration frequency obtained from lattice dynamic calculations also using GULP software followed by the Fourier-transform analysis of the projection of the trajectory of an atom on the direction of transition into an activated state. The results were used to estimate the excess anion concentrations necessary for reaching equal cationic and anionic mobilities at various temperatures; from these estimations, it was inferred that, of the systems under consideration, an internal solid-phase reaction is expected to occur only for NiO.     

Investigation of clinoptilolite rich natural zeolites from Turkey: a combined XRF,TG/DTG,DTA and DSC study

Turkey clinoptilolite-rich tuffs from Gördes and Bigadiç regions of western of Anatolia and their exchanged forms (K⁺, Na⁺, Mg²⁺ and Ca²⁺) were characterized by TG/DTG-DTA, DSC and XRF methods and the surface areas were also determined for both tuffs. TG-DTG and DTA curves of all clinoptilolite samples were measured in the temperature range 30–1000 °C. All clinoptilolite samples had major, rapid mass losses between 30 and 200 °C, with slower and less significant mass losses at higher temperatures. The mass loss of the Natural-G is 9.54% while that of the Natural-B sample is 10.50%. Water content increases in the order of K < Na < Ca < Mg for Bigadiç clinoptilolite samples and in the following sequence K < Na < Mg < Ca for Gördes clinoptilolite samples. One mass loss step for all clinoptilolite samples was observed using differential scanning calorimeter (DSC) in the range of 30–550 °C.