Self‐curable polyester by a reaction of glycidol with maleic anhydride

The controlled reaction of equimolar quantities of maleic anhydride and glycidol in dimethoxyethane gives soluble polyesters with one hydroxyl group in each repeating unit. The reaction proceeds with stepwise ring opening of the components and gives highly viscous clear solutions in relatively short periods. In the first step, monomaleate ester formation takes place around 80 °C. The ring opening of the oxirane group is the second step, and it occurs at 120 °C. The overall reaction is the formation of soluble polyesters with moderate molecular weights (6000–18,000), without the elimination of water. The soluble polyesters can be crosslinked tightly by direct heating at 190 °C without additional vinyl monomer. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2549–2555, 2003     

Therapeutic Monitoring of Isoniazid, Pyrazinamide and Rifampicin in Tuberculosis Patients Using LC

The objective of this study was to measure plasma concentration of isoniazide (INH), pyrazinamide (PZA) and rifampisin (RIF) in tuberculosis patients by using HPLC. 100 μL of plasma was deproteinized by adding trichloroacetic acid and acetonitrile to yield INH, PZA and RIF respectively. They were analysed by HPLC using a reversed phase C₁₈ pre-column linked to a 4 μm C₁₈ analytical column with a gradient solvent programme, which delivered 3% to 40% (v/v) acetonitrile in phosphate buffer in 20 min at rate of 0.8 mL min^?1. Signals were monitored by diode-array detector. Acetanilide was used as internal standard. The method is reproducible and accurate with lower limits of quantification of 0.6 mg L^?1 for INH, 1.5 mg L^?1 for PZA and 0.7 mg L^?1 for RIF. The plasma of 25 patients receiving daily standard therapy were assayed for INH, PZA and RIF 3 h after administration. Plasma concentration were found between 0.98 and 6.27 mg L^?1 for INH, 11.05 and 47.26 mg L^?1 for PZA, 5.09 and 33.20 mg L^?1 for RIF respectively. Many of the plasma levels were found to be sub therapeutic. This practical method may be used for monitoring drug plasma levels of patients who fail to respond to treatment.     

A review on design criteria for vortex tubes

In this study, the past investigations of the design criteria of vortex tubes were overviewed and the detailed information was presented on the design of them. Vortex tubes were classified and the type of them was described. All criteria on the design of vortex tubes were given in detail using experimental and theoretical results from the past until now. Finally, the criteria on the design of them are summarized.     

Novel strategy for tailoring of SiO2 and TiO2 nanoparticle surfaces with poly(ε-caprolactone)

A novel strategy was developed for tailoring of SiO₂ and TiO₂ nanoparticle surfaces with poly(ε-caprolactone) (PCL). Thus, a self-curable polyester, poly(2-hydroxypropylene maleate) was adsorbed on the nanoparticle surfaces and heated to 180 °C to give a cross-linked polyester layer with residual hydroxyalkyl groups on their surfaces. Surface-initiated polymerization of ε-caprolactone from hydroxyalkyl groups on the surfaces yielded core-shell nanoparticles with cross-linked core and PCL shells (22.2–71.4%). The organic shell layers around the nanoparticle cores were evidenced by transmission electron microscopy, dynamic light scattering, and thermogravimetric analyses techniques. The core-shell nanoparticles were then employed in preparing the stable and the homogenous dispersions with poly(methyl methacrylate-stat-butyl acrylate) solutions. An application of the solutions onto glass substrates yielded uniform and nearly transparent free standing films (40–60 μm) with good homogeneity as inferred from scanning electron microscopy pictures.     

Robust multigrid preconditioners for the high‐contrast biharmonic plate equation

We study the high‐contrast biharmonic plate equation with Hsieh–Clough–Tocher discretization. We construct a preconditioner that is robust with respect to contrast size and mesh size simultaneously based on the preconditioner proposed by Aksoylu et al. (Comput. Vis. Sci. 2008; 11 :319–331). By extending the devised singular perturbation analysis from linear finite element discretization to the above discretization, we prove and numerically demonstrate the robustness of the preconditioner. Therefore, we accomplish a desirable preconditioning design goal by using the same family of preconditioners to solve the elliptic family of PDEs with varying discretizations. We also present a strategy on how to generalize the proposed preconditioner to cover high‐contrast elliptic PDEs of order 2k, k>2. Moreover, we prove a fundamental qualitative property of the solution to the high‐contrast biharmonic plate equation. Namely, the solution over the highly bending island becomes a linear polynomial asymptotically. The effectiveness of our preconditioner is largely due to the integration of this qualitative understanding of the underlying PDE into its construction. Copyright © 2010 John Wiley & Sons, Ltd.     

The effect of quaternary element on the thermodynamic parameters and structure of CuAlMn shape memory alloys

In this study, the Cu-based shape memory alloys were produced by arc melting. We have investigated the effects of the alloying elements on the characteristic transformation temperatures, enthalpy, entropy values, and the structure of Cu–Al–Mn ternary system. The evolution of the transformation temperatures was studied by the differential scanning calorimetry. The characteristic transformation temperatures can be controlled by the variations in the aluminum and manganese content. Additionally, the effect of magnesium and iron on the transformation temperatures and thermodynamic parameters was investigated in the Cu–Al–Mn ternary system. The addition of the magnesium decreases the characteristic transformation temperatures of the Cu–Al–Mn system, but that of the iron increases. The structural changes of the samples were studied by X-ray diffraction measurements and optical microscope observations. Due to the low solubility of the magnesium, the magnesium addition into the Cu–Al–Mn system forms precipitates in the matrix. It is evaluated that the transformation parameters of the CuAlMn shape memory alloys can be controlled by the change of the alloying elements and the weight percentages of alloying elements.     

Experimental and numerical investigation of pressure drop coefficient and static pressure difference in a tangential inlet cyclone separator

The aim of this study was to investigate the pressure drop coefficient and the static pressure difference related to the natural vortex length and to evaluate the results for gas-particle applications. CFD simulations were carried out using a numerical technique which had been verified previously. Results obtained from the numerical simulations were compared with the experimental data. Analysis of the results showed that the pressure drop coefficient decreases with the increasing inlet velocity, becoming almost constant above a certain value of the inlet velocity. The reason is that the effect of viscous forces decreases at high Reynolds numbers. The pressure drop coefficient also decreases with the increasing exit pipe diameter and decreasing exit pipe length.     

Improving image quality of diagnostic ultrasound by using the safe use time model with the dynamic safety factor and the effect of the exposure time on the image quality

Resolution and penetration are primary criteria for image quality of diagnostic ultrasound. In theory (and usually in practice), the maximum depth of imaging in a tissue increases as power (pressure) is increased. Alternatively, at a particular effective penetration, an increased power may be used to allow a higher ultrasound frequency for higher resolution and tissue contrast. Recently, Karagoz and Kartal [29] proposed a safety parameter for thermal bioeffects of diagnostic ultrasound; that is, SUT (safe use time). The SUT model is constructed to determine how long one piece of tissue can be insonated safely according to a threshold exposure. Also, Karagoz and Kartal [29] suggested that an increase in acoustic intensity beyond the current US Food and Drug Administration (FDA) limit of intensity can be theoretically possible by using SUT model while staying within the safe limit. The present study was motivated particularly by the goals of higher resolution and/or deeper penetration by using SUT model. The results presented here suggest that the safe use of higher exposure levels than currently allowed by the FDA may be possible for obtaining substantial improvements in penetration depth and/or resolution. Also, the study reveals that image quality can be functionally related to exposure time in addition to acoustic energy and frequency.     

Synthesis of some furo‐thiazolidine derivatives starting from aldimines

Alkyl and aryl substituted furothiazolidine derivatives have been synthesized by the reaction of Wittig reagent with benzylidene derivatives of 4‐thiazolidinones obtained from aldimines and thioglicolic acid.