A two‐grid stabilization method for solving the steady‐state Navier‐Stokes equations

We formulate a subgrid eddy viscosity method for solving the steady‐state incompressible flow problem. The eddy viscosity does not act on the large flow structures. Optimal error estimates are obtained for velocity and pressure. The numerical illustrations agree completely with the theoretical results. © 2005 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2005     

Molecular and crystal structure of 2-{(<Emphasis Type="Italic">E</Emphasis>)-[(4-Methylphenyl)imino]methyl}-4-nitrophenol: A redetermination

The crystal structure of the title compound, C₁₄H₁₂N₂O₃, was recently determined as a mixture of its neutral (OH containing) and zwitterionic (NH containing) forms, in a 0.60 (4): 0.40 (4) ratio using the X-ray determination. In this study, the title compound has been characterized by FT-IR and X-ray diffraction. The redetermination showed that the title compound has only enol (OH) form because of lack of the NH stretching vibration in FT-IR spectrum. In addition, the molecular structure and tautomerism of the title compound have been discussed.     

Propolis-Based Nanofiber Patches to Repair Corneal Microbial Keratitis

In this research, polyvinyl-alcohol (PVA)/gelatin (GEL)/propolis (Ps) biocompatible nanofiber patches were fabricated via electrospinning technique. The controlled release of Propolis, surface wettability behaviors, antimicrobial activities against the S. aureus and P. aeruginosa, and biocompatibility properties with the mesenchymal stem cells (MSCs) were investigated in detail. By adding 0.5, 1, and 3 wt.% GEL into the 13 wt.% PVA, the morphological and mechanical results suggested that 13 wt.% PVA/0.5 wt.% GEL patch can be an ideal matrix for 3 and 5 wt.% propolis addition. Morphological results revealed that the diameters of the electrospun nanofiber patches were increased with GEL (from 290 nm to 400 nm) and Ps addition and crosslinking process cause the formation of thicker nanofibers. The tensile strength and elongation at break enhancement were also determined for 13 wt.% PVA/0.5 wt.% GEL/3 wt.% Ps patch. Propolis was released quickly in the first hour and arrived at a plateau. Cell culture and contact angle results confirmed that the 3 wt.% addition of propolis reinforced mesenchymal stem cell proliferation and wettability properties of the patches. The antimicrobial activity demonstrated that propolis loaded patches had antibacterial activity against the S. aureus, but for P. aeruginosa, more studies should be performed.     

Synthesis and Characterization of Some N-substituted Polypyrrole Derivatives: Towards Glucose Sensing Electrodes

Synthesis and chemical oxidative polymerization of some N-substituted pyrroles ((N-Py)s) were carried out using Clauson-Kaas method and FeCl₃ in CHCl₃ medium, respectively. The produced polymers, N-(p-benzoic acid)polypyrrole (NpbPPy); N-(o-aminophenyl)polypyrrole (NoaPPy); N-(m-nitrophenyl) polypyrrole (NmnPPy), were characterized by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) analysis. An enzymatic glucose biosensor is fabricated through immobilizing glucose oxidase (GOX) into N-substitued polypyrrole matrixes. The parameters affecting the fabrication and experimental conditions of biosensors were optimized. The best biosensor results were obtained for NpbPPy matrix. The sensitivity of the proposed biosensor permitted the determination of glucose in the concentration range of 0–9.2 M with a detection limit of 1× 10^{? 6}. The apparent Michaelis–Menten constant (K_M ^app) for the sensor was found to be 25.95 mM.     

Gross alpha and beta activities of airborne particulate samples from Wawel Royal Castle Museum in Cracow, Poland

PM-10, PM-2.5 and PM-1.0 concentrations were measured over an 8 h period at sites both inside and outside the museum of Wawel Royal Castle in Cracow, Poland. Gross alpha (α) and beta (β) activities seemed to vary across the particle size range with generally higher levels of activities in the PM-2.5 particle fraction, and higher activities in the PM-10 fraction, while both the highest and the lowest beta activities were found in PM-1.0 fraction. However, statistically there was no significant difference. The highly radioactive PM-1.0 fraction comprised mainly ²¹⁰Pb and the ²¹⁰Pb progeny, ²¹⁰Bi and ²¹⁰Po, and can be attributed to anthropogenic sourced outdoor radioactive particles brought indoors by visitors. ²¹⁰Pb is considered to be a good tracer of secondary aerosols produced by gas-to-particle conversion. Inside the Museum, the highest level of gross alpha activity was detected in the PM-10 fraction, and was mainly due to the uranium isotopes (²³⁴U, ²³⁵U and ²³⁸U) and their daughter products (²²⁶Ra, ²³²Th, ²¹⁰Po or ²²⁴Ra), and ¹³⁷Cs. The minimum and maximum total indicative doses per 8 h are caused by ¹³⁷Cs and ²³²Th, respectively.     

Polarized-Beam High-Energy EDXRF in Geological Samples

Certified reference materials (NIST 1645, BCR 143, IAEA 7, BCR 141, NIES_CRM_02, and IAEA 375) were used for determining the performance of a secondary target energy-dispersive X-ray fluorescence (EDXRF) spectrometer, Epsilon 5 (PANalytical, Almelo, the Netherlands). For the evaluation of the EDXRF spectra with polarized-beam high-energy excitation, the WinAxil software package has been applied. The results showed that Epsilon 5, EDXRF spectrometry is favorable for the determination of elemental concentrations in geological samples, but the sample preparation has the largest influence on the precision. However, they presented good agreement with certified values for most of the elements.     

Some Novel Conducting Polythiophene Derivatives: Theoretical Analysis,Synthesis, Characterization and Electroreological Properties

A series of alternating phylene and symmetrically bithiophene containing repeat units and the respective homopolymers have been synthesized and characterized by combining FTIR, UV-Vis spectroscopy, four probe conductivity measurement, TGA and SEM analysis. Quantum mechanical calculations of the structures and infrared spectra of the monomers and respective dimers were compared with experimental results. The polymers are soluble in N-methyl-pyrrolidone (NMP). The samples have conductivities of 10^?5 S/cm levels. Thermal degradation analysis results indicated that poly-bithiophene derivatives have higher thermal stabilities than poly-monothiophene derivatives. All samples exhibited different surface morphologies. The electrorheological (ER) properties of polymer suspensions in silicone oil were prepared and ER behavior was investigated as a function of shear rate, electric field strength and frequency.     

The natural phenolic compounds and their antioxidant and anticholinesterase potential of herb Leiotulus dasyanthus (K. Koch) Pimenov & Ostr.

Abstract

The presented work reports anticholinesterase and antioxidant activities of extracts, fractions from aerial parts, fruits, flowers, roots and isolated compounds of roots from Leiotulus dasyanthus (bergapten, pimpinellin, umbelliferone, quercetin, rutin and kaempferol). Phenolic contents, antioxidant activities of samples were carried out by Folin-Ciocalteu, DPPH, TBA methods. Anticholinesterase activity was evaluated by Ellman’s method. The highest and lowest total phenolic content were detected in root MeOH extract (88.6?mg GAE g^?1 DW) and aerial part (51.83?mg GAE g^?1 DW), respectively. The highest antioxidant activity among isolated secondary metabolites got coumarins umbelliferone, bergapten and pimpinellin. Pimpinellin (66.55%) and umbelliferone (61.09%) demonstrated strong inhibition towards acetylcholinesterase and butyrylcholinesterase, respectively. Dichloromethane fraction of root demonstrated significant inhibition against AChE (49.66%) and BuChE (92.21%) at 20 µg/mL. Dichloromethane fractions of roots had a notableness antioxidant and anticholinesterase activities. The further studies on roots will be important for development use of this plant for pharmaceutical and food research needs.

     

Crystal Structure of 2-((<Emphasis Type="Italic">E</Emphasis>)-(5-Bromo-2- hydroxybenzylidene)hydrazono)-1,2-diphenylethanone

The molecular structure of the title compound, C₂₁H₁₅Br₁N₂O₂, was characterized by single crystal X-ray diffraction. The compound crystallizes in the triclinic sp. gr. \(P\bar 1\) with Z = 2. The molecule is not planar: the dihedral angle between the planes of two aromatic rings [C1/C6] and [C16/C21] is 84.9(2)°. The other dihedral angle between two aromatic rings [C9/C14] and [C16/C21] is 88.8(2)°. The title compound exists as a phenol-imine tautomer, in which a strong intramolecular O–H···N hydrogen bond is formed. This study verifies the preference of the phenol-imine tautomeric form in the solid state. A π–π stacking interactions are also observed, which may influence crystal stability: the distance between centroids is 3.702(2) Å.     

Molecular and Crystal Structure of 2-{(<Emphasis Type="Italic">E</Emphasis>)-[(5-Chloro-2-methoxyphenyl)imino]methyl}-4-nitrophenol

The molecular structure of the title compound, C₁₄H₁₁ClN₂O₄, was determined by single crystal X-ray diffraction. The compound crystallizes in the monoclinic sp. gr. P2₁/c with Z = 4. The title compound, C₁₄H₁₁ClN₂O₄, is a Schiff base which adopts the phenol-imine tautomeric form in the solid state.The molecule is almost planar and the dihedral angle between the planes of two aromatic ring is 2.2(1)°. The molecular structure is stabilized by intramolecular O–H···N hydrogen bond which generates a six-membered ring. In the crystal structure, the molecules are linked together by intermolecular C–H···O interactions.