2-Absorbing and Weakly 2-Absorbing Elements in Multiplicative Lattices

In this article we study weakly 2-absorbing elements and 2-absorbing elements in C-lattices. Next we characterize C-lattices in which every nonzero proper element is a (weakly) 2-absorbing element. We also establish a new characterization for principal element domains in terms of 2-absorbing elements.     

Removal of Pb2+ and Cd2+ ions from aqueous solutions using guanidine modified hydrogels

In this study, experimental measurements have been made on the batch adsorption of cadmium and lead ions from aqueous solutions using poly(guanidine modified 2‐acrylamido‐2‐methylpropan sulfonic acid/acrylic acid/N‐vinylpyrrolidone/2‐Hydroxyethyl methacrylate), P(AMPSG/AAc/NVP/HEMA) hydrogels. The guanidyl end group bearing AMPSG monomer was synthesized from the reaction of AMPS and guanidine. The hydrogels were prepared by UV‐curing technique. The morphology of the dry H10‐hydrogel sample was examined by SEM. The influence of the uptake conditions, such as pH, functional monomer per cent, contact time, initial feed concentration, and foreign metal ions on the metal ion binding capacity of hydrogel, was also tested. The selectivity of the hydrogel toward the different metal ions tested was Hg(II) > Pb(II) > Au(III) > Cd(II). The adsorption isotherm models were applied to the experimental data, and it was seen that the Langmuir isotherm model was the best fit for the adsorption of Cd(II) and Pb(II) ions on P(AMPSG/AAc/NVP/HEMA) hydrogel. It was found that adsorbed lead and cadmium ions on P(AMPSG/AAc/NVP/HEMA) hydrogel can be effectively desorbed by acid leaching and the regenerated P(AMPSG/AAc/NVP/HEMA) hydrogel can be reused almost five times less without any loss of adsorption capacity. Copyright © 2009 John Wiley & Sons, Ltd.     

Influences of Electrolytes, Polymers and a Surfactant on Rheological Properties of Bentonite–Water Systems

Characteristic rheological properties, such as viscosity, shear stress, yield point, gel strength and thixotropy, of natural Ca- bentonite and Na-peptized bentonite were studied after adding LiCl, KCl, CaCl2, MgCl2·6H2O electrolytes; (NaPO3)n, polyvinyl pyrolidone (PVP) polymers and an anionic surfactant (linear alkyl benzene sulphonate, LABS). Changes in flow properties under the influence of various additives at different quantities were investigated in these slurries. The experimental results are discussed in terms of bentonite forms, types and concentrations of additives and influence of exchangeable cations. Bivalent and monovalent cations display entirely different rheological properties in two groups of muds. Furthermore, the difference in the degree of activity of PVP polymer on the viscosity of two mud systems depend on the clay mineral structure. The slurry prepared with Na-bentonite contains a minimum number of tactoids and a maximum number of sheet-bearing clay particles, which reduces the surface area of the clay minerals and increases viscosity by adding PVP polymer.     

The role of iron and zinc in chemotherapy-induced alopecia

Chemotherapy-induced alopecia is a common and distressing side effect in children with cancer. Iron and zinc are the well known trace elements which are associated with hair shedding. In this study, we investigated the hair content of iron and zinc in children with cancer consists of two groups: group A, newly diagnosed patients; group B, the patients received a course of chemotherapy. We compared the results between each others and healthy controls. Hair content of iron and zinc was not different between the patient groups. Iron concentrations of patient samples, either at diagnosis or after chemotherapy, were significantly lower than healthy controls. However, there was no statistically significant difference between the groups regarding the zinc values. In conclusion, hair content of iron and zinc do not have a role in chemotherapy-induced alopecia.     

Boundary-layer flow about a vertical spinning cone under mixed thermal boundary conditions and a magnetic field

A similarity analysis was performed to investigate the laminar boundary-layer flow in the presence of a transverse magnetic field over a down-pointing and spinning cone with mixed thermal boundary conditions. Boundary layer velocity and temperature profiles were determined numerically for various values of the magnetic and spin parameters and the Prandtl number. The spin of the cone compresses the velocity profiles towards the surface by inducing an upward flow and decreases the surface temperature. The magnetic field suppresses the velocity profiles and increases the surface temperature. A transformation relating the similarity solutions of the boundary-layer velocity and temperature profiles associated with different values of the mixed thermal boundary condition parameter was obtained.     

Vibration of a variable cross-section beam

Vibration of an isotropic beam which has a variable cross-section is investigated. Governing equation is reduced to an ordinary differential equation in spatial coordinate for a family of cross-section geometries with exponentially varying width. Analytical solutions of the vibration of the beam are obtained for three different types of boundary conditions associated with simply supported, clamped and free ends. Natural frequencies and mode shapes are determined for each set of boundary conditions. Results show that the non-uniformity in the cross-section influences the natural frequencies and the mode shapes. Amplitude of vibrations is increased for widening beams while it is decreased for narrowing beams.     

Investigation of the spontaneous emission rate of perylene dye molecules encapsulated into three-dimensional nanofibers via FLIM method

The decay dynamics of perylene dye molecules encapsulated in polymer nanofibers produced by electrospinning of polymethyl methacrylate are investigated using a confocal fluorescence lifetime imaging microscopy technique. Time-resolved experiments show that the fluorescence lifetime of perylene dye molecules is enhanced when the dye molecules are encapsulated in a three-dimensional photonic environment. It is hard to produce a sustainable host with exactly the same dimensions all the time during fabrication to accommodate dye molecules for enhancement of spontaneous emission rate. The electrospinning method allows us to have a control over fiber diameter. It is observed that the wavelength of monomer excitation of perylene dye molecules is too short to cause enhancement within nanofiber photonic environment of 330 nm diameters. However, when these nanofibers are doped with more concentrated perylene, in addition to monomer excitation, an excimer excitation is generated. This causes observation of the Purcell effect in the three-dimensional nanocylindrical photonic fiber geometry.     

Ionic Liquid Modified Single‐use Electrode Developed for Voltammetric Detection of miRNA‐34a and its Application to Real Samples

The ionic liquid (IL) modified chemically activated (CA) pencil graphite electrodes (PGEs) were developed for label‐free voltammetric detection of miRNA‐34a, and implemented to the real samples. Firstly, the electrochemical characterization of unmodified PGE, CA‐PGE, IL‐PGE and IL‐CA‐PGE was performed by cyclic voltammetry (CV) as well as their DNA binding capacity was studied by electrochemical impedance spectroscopy (EIS) technique. The microscopic characterization of the surface of each electrodes was investigated by scanning electron microscopy (SEM). Differential pulse voltammetry (DPV) technique was used for measuring the oxidation signal of guanine in order to perform a label‐free voltammetric monitoring of a full‐match hybridization specific to miRNA‐34a. The selectivity of biosensor was tested against to miRNA‐155, miRNA‐660 as well as to the mismatch sequence of miRNA‐34a. The further selectivity of this proposed biosensor was studied in the mixture of samples containing miRNA‐34a with other miRNAs (1 : 1). The voltammetric detection of miRNA‐34a was also explored in the artificial serum medium as fetal bovine serum (FBS) and also in total RNA samples isolated from HUH‐7 human hepatocellular carcinoma cell line.     

Application of carbon arc‐generated Mo‐ and W‐based catalyst systems to the ROMP of norbornene

This study focuses on the application of the carbon arc‐generated molybdenum‐ and tungsten‐based catalyst systems, MoCl₅? C and WCl₆? C, to effect ring‐opening metathesis polymerization (ROMP) of bicyclo[2.2.1]hept‐2‐ene (norbornene). The results are compared with those previously obtained by the electrochemically generated MoCl₅? ē? Al? CH₂Cl₂ and WCl₆? ē? Al? CH₂Cl₂ systems. The polymer products are characterized using ¹H and ¹³C NMR, gel permeation chromatography, differential scanning calorimetry and thermo gravimetric analysis. According to NMR spectra analyses, the molybdenum‐based catalyst system produced polynorbornene with ca 48% cis structure whereas tungsten system produced ca 56% cis structure polynorbornene and in both cases the polynorbornene had a blocky distribution. Copyright © 2009 John Wiley & Sons, Ltd.