Removal of Phenolic and Lignin Compounds from Bleached Kraft Mill Effluent by Fly Ash and Sepiolite

This study aimed to remove phenolic and lignin compounds from paper mill industry (4500 m³/h) wastewaters, which is discharged to sea from a plant located in the western Turkey. As adsorbent, fly ash, raw sepiolite and heat-activated sepiolite were used. The effect of factors such as, particle size, temperature and pH on adsorption process was investigated. From kinetic studies, equilibrium time was found as 1 h for both. The kinetic data supports pseudo-second order model but shows very poor fit for pseudo-first order model. Intraparticle model also shows that there are two separate stages in sorption process, namely, external diffusion and pore diffusion. Adsorption isotherms for fly ash and activated sepiolite were obtained at two different temperatures. From experiments carried out at different pHs, it was observed that pH plays an important role in the adsorption process in removing of both lignin and phenolic compounds, providing both ionizating the compounds and modifying sorbent surfaces. It was also observed that heat-activated sepiolite is more effective than raw sepiolite and fly ash to remove these compounds. Adsorption of lignin and phenolic compounds increases with decreasing particle size. In addition, the efficiency of adsorption decreases with increasing adsorption temperature for both fly ash and untreated sepiolite.     

Higher order boundary value problems on time scales

In this paper we study the existence of solutions for Lidstone boundary value problems on time scale. Firstly, by using Schauder fixed point theorem in a cone, we obtain the existence of solutions to a Lidstone boundary value problem (LBVP). Secondly, existence result for this problem is also given by the monotone method. Finally, by using Krasnosel'skii fixed point theorem, it is proved that the LBVP has a positive solution.     

Transition Metal-Free Synthesis of meta-Bromo- and meta-Trifluoromethylanilines from Cyclopentanones by a Cascade Reaction

Anilines are key constituents in biologically active compounds and often obtained from transition metal-catalyzed coupling of an aryl halide with an amine. In this work, we report a transition metal-free method for the synthesis of meta-bromo- and meta-trifluoromethylanilines starting from 3-tribromomethylcyclopentanone or 3-(2-bromo-2-chloro-1,1,1-trifluoroethyl)cyclopentanone, respectively. The scope of the transformation is shown by application of primary, secondary and aromatic amines. The reaction proceeds in acceptable to high yields (20–81 %), and allows for the synthesis of anilines with substitution patterns otherwise difficult to access.     

Determination of isoniazid and hydrazine by capillary electrophoresis with amperometric detection at a Pt-particle modified carbon fiber microelectrode

Capillary electrpphoresis (CE)/electrochemical detection (EC) for the simultane-ous determination of hydrazine and isoniazid has been developed.The electrochemical method uses a novel modified electrode dispersed with ultrafine platinum particles on the surface of a 30μm carbon fiber microelectrode.The unique characteristic of the Pt-particles modified carbon fiber microelectrode is its excellent stability.The current measurement for hydrazine is more sensitive than that of isoniazid.Selective determination of trace amount of free hydrazine in isoniazid and its formulation can be achieved at applied potential of 0.5V.     

Investigation of AlInN HEMT structures with different AlGaN buffer layers grown on sapphire substrates by MOCVD

We investigate the structural and electrical properties of Al_xIn_1–xN/AlN/GaN heterostructures with AlGaN buffers grown by MOCVD, which can be used as an alternative to AlInN HEMT structures with GaN buffer. The effects of the GaN channel thickness and the addition of a content graded AlGaN layer to the structural and electrical characteristics were studied through variable temperature Hall effect measurements, high resolution XRD, and AFM measurements. Enhancement in electron mobility was observed in two of the suggested Al_xIn_1?xN/AlN/GaN/Al_0.04Ga_0.96N heterostructures when compared to the standard Al_xIn_1–xN/AlN/GaN heterostructure. This improvement was attributed to better electron confinement in the channel due to electric field arising from piezoelectric polarization charge at the Al_0.04Ga_0.96N/GaN heterointerface and by the conduction band discontinuity formed at the same interface. If the growth conditions and design parameters of the Al_xIn_1?xN HEMT structures with AlGaN buffers can be modified further, the electron spillover from the GaN channel can be significantly limited and even higher electron mobilities, which result in lower two-dimensional sheet resistances, would be possible.     

pH‐responsive near‐infrared emitting conjugated polymer nanoparticles for cellular imaging and controlled‐drug delivery

In this article, pH‐responsive near‐infrared emitting conjugated polymer nanoparticles (CPNs) are prepared, characterized, and their stabilities are investigated under various conditions. These nanoparticles have capacity to be loaded with water insoluble, anticancer drug, camptothecin (CPT), with around 10% drug loading efficiency. The in vitro release studies demonstrate that the release of CPTs from CPNs is pH‐dependent such that significantly faster drug release at mildly acidic pH of 5.0 compared with physiological pH 7.4 is observed. Time and dose‐dependent in vitro cytotoxicity tests of blank and CPT‐loaded nanoparticles are performed by real‐time cell electronic sensing (RT‐CES) assay with hepatocellular carcinoma cells (Huh7). The results indicate that CPNs can be effectively utilized as vehicles for pH‐triggered release of anticancer drugs. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 114–122     

Rolling resistance moment of microspheres on surfaces

In the current work, for the first time, the existence of a rolling moment of resistance of an adhesion bond between a microsphere and flat surface subjected to external dynamic force has been experimentally demonstrated. The rotational motion of spherical particles deposited on a wafer is excited in the 0–3.5?MHz range using a piezoelectric transducer. The approach is based on (i) the observation that the contribution of the rotational (rocking) motion to the axial displacement of the particle are few orders of magnitude higher than those of the purely axial motion and (ii) the existence of a relationship between the rotational natural frequency of the adhesion bond and the work of adhesion. The natural frequency of the rotational (rocking) motion is extracted from the low frequency components of the transient response of the particle in the axial direction, which is measured by a laser interferometer. The existing theoretical adhesion models for rolling resistance moment are evaluated using the experimental results. Good agreement between the theoretical predictions and experimental values is found.     

Effect of exopolymeric substances on the kinetics of sorption and desorption of trivalent chromium in soil

Laboratory batch sorption-desorption and column experiments were performed to better understand the effects of microbial exopolymeric substances (EPS) on Cr(III) sorption/desorption rates in the soil-water system. The experiments were carried out in two different modes: one mode (sorption) in which Cr(III) and EPS were applied simultaneously, and the other (desorption) included the sequential application of Cr(III) and EPS to the soil-water system. The batch sorption and desorption experiments showed that, while chromium(III) desorption was significantly enhanced in the presence of EPS relative to non-EPS-containing systems, the desorption rates were much smaller than the sorption rates, and the fraction dissolved by EPS accounted for only a small portion of the total chromium initially sorbed onto soil minerals. Similarly, the column experiments suggested that, while the microbial EPS led to an increase in Cr dissolution relative to non-EPS-containing systems, only a small portion of the total chromium initially added to the soil was mobilised. The differences observed in Cr sorption and desorption rates can be explained through the very low solubility and strong interactions of chromium species with soil minerals as well as the mass transfer effects associated with low diffusion rates. The overall results suggest that, while microbial EPS may play an important role in microbial Cr(VI) treatment in sub-surface systems due to the formation of soluble Cr-EPS complexes, the extent and degree of Cr mobilisation are highly dependent on the type of initial Cr sorption.     

New method and treatment technique applied to interband transition in GaAs<Subscript>1−<Emphasis Type="Italic">x</Emphasis></Subscript>P<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript> ternary alloys

In this paper we presented a new method (Eigen-Coordinates (ECs)) that can be used for calculations of the critical points (CPs) energy of the interband-transition edges of the heterostructures. This new method is more accurate and complete in comparison with conventional ones and has a wide range of application for the calculation of the fitting parameters related to nontrivial functions that initially have nonlinear fitting parameters that are difficult to evaluate. The new method was applied to determine the CPs energies from the dielectric functions of the MBE grown GaAs_1−xP _x ternary alloys obtained using spectroscopic ellipsometry (SE) measurements at room temperature in the 0.5-5 eV photon energy region. The obtained results are in good agreement with the results of the other methods.     

Investigating the vortex melting phenomenon in BSCCO crystals using magneto-optical imaging technique

Using a novel differential magneto-optical imaging technique we investigate the phenomenon of vortex lattice melting in crystals of Bi₂Sr₂CaCu₂O₈ (BSCCO). The images of melting reveal complex patterns in the formation and evolution of the vortex solid-liquid interface with varying field (H)/temperature (T). We believe that the complex melting patterns are due to a random distribution of material disorder/inhomogeneities across the sample, which create fluctuations in the local melting temperature or field value. To study the fluctuations in the local melting temperature/field, we have constructed maps of the melting landscape T _m(H, r), viz., the melting temperature (T _m) at a given location (r) in the sample at a given field (H). A study of these melting landscapes reveals an unexpected feature: the melting landscape is not fixed, but changes rather dramatically with varying field and temperature along the melting line. It is concluded that the changes in both the scale and shape of the landscape result from the competing contributions of different types of quenched disorder which have opposite effects on the local melting transition.