Synthesis and Characterization of Indium-borate Glass-ceramics Containing Ho0.01Ce0.74Zr0.25O1.995 Nanorods via Incorporation Method

Glasses in the system 5In₂O₃·94Na₂B₄O₇ were fabricated via melt quenching technique. The amorphous nature of the quenched glasses was confirmed by X‐ray powder diffraction studies, and the infrared spectra of the glasses show no boroxol ring formation in the structure of these glasses. Differential thermal analysis is shown glass transition temperature 696°C and crystallization temperature 1151°C. A cerium‐zirconium mixed oxide Ce_0.75Zr_0.25O₂ and Ho‐doped cerium‐zirconium mixed oxide were obtained by solid‐state method. Then glass powder and Ho‐doped cerium‐zirconium mixed oxide were mixed. The mixture was heated in a crucible. The glass‐ceramic sample was obtained by pouring the melts on stainless steel. Obtained samples were annealed at 450°C for 1 h to remove thermal strain. Differential thermal analysis for glass‐ceramic sample is shown glass transition temperature 668°C and crystallization temperature 1159°C. The scanning electron microscopy study for glass‐ceramic indicates that the crystallized glass consists of rod‐like crystals with average diameter of about 38 nm dispersed in the glassy regions.     

Biotransformation of naringenin to eriodictyol by Saccharomyces cerevisiea functionally expressing flavonoid 3' hydroxylase

To increase the biological activities of flavonoids and to enhance their stability and solubility by functionalization reactions (polymerization, esterification, alkylation, glycosylation and acylation), an increase in the number of hydroxyl groups in these molecules is needed. Hydroxylation reactions may be achieved using either chemical or enzymatic methods, the latter being more highly specific than the former. In our study, the flavonoid 3' hydroxylase (F3'H) from Gerbera hybrid, functionally expressed in Saccharomyces cerevisiae, was used to hydroxylate naringenin (the first flavonoid core synthesized in plants). Furthermore, we studied factors that may affect naringenin hydroxylation by recombinant cell-like yeast growth on selective or rich media and plasmid stability. The whole recombinant cells hydroxylated naringenin at position 3' to give eriodictyol. In a selective media, the yeast failed to grow to high cell densities (maximum 5 g/L), but the plasmid stability was nearly 90%, and naringenin hydroxylation reached 100%. In a rich complex media, the biomass reached 10 g/L, but the yield of naringenin hydroxylation reached only 71%, and the plasmid stability decreased. When yeast functionally expressing F3'H from Gerbera hybrid was used, in a selective media, 200 mg/L of eriodictyol from naringenin was produced.     

Ethyl 3‐[1‐(5,5‐dimethyl‐2‐oxo‐1,3,2‐dioxaphosphorin‐2‐yl)propan‐2‐ylidene]carbazate: a combined X‐ray and density functional theory (DFT) study

In the title compound, C₁₁H₂₁N₂O₅P, one of the two carbazate N atoms is involved in the C=N double bond and the H atom of the second N atom is engaged in an intramolecular hydrogen bond with an O atom from the dimethylphosphorin‐2‐yl group, which is in an uncommon cis position with respect to the carbamate group. The cohesion of the crystal structure is also reinforced by weak intermolecular hydrogen bonds. Density functional theory (DFT) calculations at the B3LYP/6‐311++g(2d,2p) level revealed the lowest energy structure to have a Z configuration at the C=N bond, which is consistent with the configuration found in the X‐ray crystal structure, as well as a less stable E counterpart which lies 2.0 kcal mol⁻¹ higher in potential energy. Correlations between the experimental and computational studies are discussed.     

Design of an Imipramine‐Selective Electrode Based on an Ion‐Pair and its Application to Pharmaceutical Analysis

Ion‐selective electrodes play an important role in pharmaceutical analysis due to their simplicity, rapidity and accuracy over some other analytical methods. This research introduces the design of an ion‐pair of imipramine‐tetraphenyl borate (IMP‐TPB) based PVC membrane sensor for IMP hydrochloride determination. Effect of the membrane composition, the pH influence and the effect of lipophilic anionic additives on the response characteristics of the electrode were investigated. After a series of experiments, the best electrode performance was accomplished with a membrane composition of 30% PVC, 63% DBP, 5% (IMP‐TPB) and 2% (NaTPB). This electrode illustrated a fast (15 s), stable and Nernstian response across a relatively wide IMP hydrochloride concentration range (10^?5 to 10^?5 M), in the pH range of (3.0–8.0), and it can be used for at least two months without any measurable change in sensitivity. Additionally, the interference between IMP and several drugs and common inorganic anions was negligible as shown by the potentiometric selectivity coefficient data. The membrane sensor was successfully applied to the determination of IMP in tablets and human urine samples, and very good recovery results were obtained.     

Spin 0 and Spin 1/2 Particles in a Spherically Symmetric Static Gravity and a Coulomb Field

A relativistic particle in an attractive Coulomb field as well as a static and spherically symmetric gravitational field is studied. The gravitational field is treated perturbatively and the energy levels are obtained for both spin 0 (Klein-Gordon) and spin 1/2 (Dirac) particles. The results are shown to coincide with each other as well as the result of the nonrelativistic (Schr?dinger) equation in the nonrelativistic limit.     

Study of a Generalized Nonlinear Euler-Poisson-Darboux System: Numerical and Bessel Based Solutions

In this paper a nonlinear Euler-Poisson-Darboux system is considered. In a first part, we proved the genericity of the hypergeometric functions in the development of exact solutions for such a systemin some special cases leading to Bessel type differential equations. Next, a finite difference scheme in two-dimensional case has been developed. The continuous system is transformed into an algebraic quasi linear discrete one leading to generalized Lyapunov-Sylvester operators. The discrete algebraic system is proved to be uniquely solvable, stable and convergent based on Lyapunov criterion of stability and Lax-Richtmyer equivalence theorem for the convergence. A numerical example has been provided at the end to illustrate the efficiency of the numerical scheme developed in section 3. The present method is thus proved to be more accurate than existing ones and lead to faster algorithms.     

Analysis of polyvinyl alcohol microbubbles in human blood plasma using capillary electrophoresis

Recently, a new type of ultrasound contrast agent that consists of air‐filled microbubbles stabilized with a shell of polyvinyl alcohol was developed. When superparamagnetic nanoparticles of iron oxide are incorporated in the polymer shell, a multimodal contrast agent can be obtained. The biodistribution and elimination pathways of the polyvinyl alcohol microbubbles are essential to investigate, which is limited with today's techniques. The aim of the present study was, therefore, to develop a method for qualitative and quantitative analysis of microbubbles in biological samples using capillary electrophoresis with ultraviolet detection. The analysis parameters were optimized to a wavelength at 260 nm and pH of the background electrolyte ranging between 11.9 and 12. Studies with high‐intensity ultrasonication degraded microbubbles in water showed that degraded products and intact microbubbles could be distinguished, thus it was possible to quantify the intact microbubbles solely. Analysis of human blood plasma spiked with either plain microbubbles or microbubbles with nanoparticles demonstrated that it is possible to separate them from biological components like proteins in these kinds of samples.     

Ureasil–polyether hybrid blend with tuneable hydrophilic/hydrophobic features based on U-PEO1900 and U-PPO400 mixtures

Urea-cross-linked polyether-siloxane hybrid blends with tuneable hydrophilic/hydrophobic features were prepared from a mixture of poly(ethylene oxide) (PEO1900) and poly(propylene oxide) (PPO400), hybridized by end-chain functionalization with (3-isocyanatopropyl)triethoxysilane. The aim of this study was to demonstrate that the combination of the different polyether phases produces materials with hydrophilic and hydrophobic properties. An anti-fog coating and a transparent monolithic swellable hydrogel were produced from the PEO1900 hybrid. Swellability and drug release profiles could be easily tuned by varying the ureasil–PEO/ureasil–PPO ratio in the hybrid matrix. Differential scanning calorimetry (DSC) and small angle X-ray scattering (SAXS) analyses indicated that the nanostructure of the hybrid blends could be described by the existence of a biphasic mixture of PEO1900-rich and PPO400-rich phases, with a fraction of the lamellar domains being derived from the PEO1900 crystallinity. A correlation between the nanoscopic features and the kinetics of the swelling mechanism is proposed, based on the results of in situ SAXS analyses. In vitro monitoring using UV–Vis spectroscopy indicated that the kinetics of drug release from the PEO1900:PPO400 hybrid blends could be controlled by varying the proportions of the hydrophilic (PEO1900) and hydrophobic (PPO400) hybrids. The response to pH change and to application of a magnetic field to the PEO1900-magnetite nanocomposite indicated that the production of stimuli-responsive delivery devices based on ureasil–PE should be feasible in the near future.