Synthesis of polyaniline nanostructures in micellar solutions

Polymerization of aniline nanoparticles was carried out in aqueous micellar solutions of surfactants, including anionic (sodium dodecyl sulfate), nonionic (nonyl phenol ethoxylate), and cationic (cetyltrimethyl ammonium bromide) surfactants. The size and morphology of these synthesized PANI nanoparticles strongly depended on the structure of the surfactants used in the formation of micelles, as shown by transmission electron microscopy. Scanning electron microscopy, Fourier transform infrared spectroscopy, and X‐ray diffraction were used in the characterization of the synthesized PANI nanoparticles. The PANI nanoparticles revealed enhanced conductivity compared to conventional bulk PANI. In addition PANI–poly(methyl methacrylate) (PMMA) nanocomposites were synthesized. The results revealed that the PMMA nanoparticles retarded thermal decomposition and enhanced the conductivities compared with pristine PANI nanoparticles. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Design and optimization of multi‐band Wilkinson power divider

In this paper, a general and easy procedure for designing the symmetrical Wilkinson power divider that achieves equal‐power split at N arbitrary frequencies is introduced. Each quarter‐wave branch in the conventional Wilkinson divider is replaced by N sections of transmission lines, and the isolation between the output ports is achieved by using N resistors. The design parameters are the characteristic impedances and lengths of the N transmission line sections, and the N isolation resistors. The even–odd modes of analysis are used to derive the design equations. Closed‐form expressions, which are suitable for CAD purposes, are derived for the dual‐band divider. For N ≥ 3, closed‐form expressions are not available, and therefore, the powerful particle swarm optimization method is used to obtain the design parameters. Examples of the dual‐, triple‐, and quad‐band dividers are presented to validate the proposed design procedure, and the results are compared, wherever possible, with published results using other methods. © 2007 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2008.     

Diabetic gastroparesis]

OBJECTIVES: This study was undertaken to determine the clinical usefulness of nuclear matrix protein 22 (NMP22) as a novel urine marker for urothelial cancer, particularly, to substitute for voided-urine cytology. METHODS: NMP22 values were determined for 280 patients and 20 healthy volunteers by NMP22 Test Kit based on an enzyme-linked immunosorbent assay. RESULTS: When the cut-off value was set at 10 U/ml, the positive rate of urinary NMP22 for urothelial cancer was 80.9% (38/47), whereas that for posttreatment cases and benign diseases was 35.7% (74/207). When urinary NMP22 and voided-urine cytology were compared, the test for urinary NMP22 showed higher sensitivity than cytology in patients with urothelial cancer. When urinary NMP22 values were determined pre- and postoperatively in patients with urothelial cancer, the postoperative value decreased in all patients, and were below the cut-off value in all except one patient. CONCLUSIONS: Urinary NMP22 is a useful diagnostic marker as a substitute for voided-urine cytology for the surveillance of urothelial cancer.     

Genome search in celiac disease

Celiac disease (CD), a malabsorption disorder of the small intestine, results from ingestion of gluten. The HLA risk factors involved in CD are well known but do not explain the entire genetic susceptibility. To determine the localization of other genetic risk factors, a systematic screening of the genome has been undertaken. The typing information of 281 markers on 110 affected sib pairs and their parents was used to test linkage. Systematic linkage analysis was first performed on 39 pairs in which both sibs had a symptomatic form of CD. Replication of the regions of interest was then carried out on 71 pairs in which one sib had a symptomatic form and the other a silent form of CD. In addition to the HLA loci, our study suggests that a risk factor in 5qter is involved in both forms of CD (symptomatic and silent). Furthermore, a factor on 11qter possibly differentiates the two forms. In contrast, none of the regions recently published was confirmed by the present screening.     

A “Globally” Convergent Controller for Multi-Machine Power Systems Using Structure-Preserving Models

The design of excitation controllers to improve transient stabilization of power systems is a topic of renewed interest in the control community. Existence of a state-feedback stabilizing law for multi-machine aggregated reduced network models has recently been established. In this paper we extend this result in two directions: first, in contrast with aggregated models, we consider the more natural and widely popular structure-preserving models that preserve the identity of the network components (generators, loads and lines) and allow for a more realistic treatment of the loads. Second, we explicitly compute a control law that, under a detectability assumption, ensures that all trajectories converge to the desired equilibrium point, provided that they start and remain in the region where the model makes physical sense.     

Theoretical modeling of cavity-backed patch antennas using a hybridtechnique

A hybrid technique that combines the method of moments (MoM) and the finite element method (FEM) to analyze cavity-backed patch antennas is presented. This technique features the use of FEM in solving the electromagnetic field distribution in the cavity and the use of MoM in solving integral equations outside the cavity. The results of MoM and FEM are combined through the continuity conditions on the boundary of the cavity. Due to the flexibility of FEM, complex cavities filled with inhomogeneous media can be analyzed by this technique. The results obtained by this hybrid technique are compared to the finite difference time domain (FDTD) results and good agreement is found     

Finite difference time domain analysis of cylindrical coplanar waveguide circuits

There is a growing interest in using cylindrical transmission line structures in microwave applications. In this paper, the finite difference time domain (FDTD) method is used to characterize several three-dimensional cylindrical coplanar waveguide (CCPW) geometries. Specifically, a CCPW series stub and a three-section CCPW filter are studied both theoretically and experimentally. Moreover, CCPW gap is characterized and the FDTD results are compared to those obtained using conformal mapping techniques. Effective absorbing boundary conditions are employed to truncate the FDTD mesh at the end walls and the outer radial boundary.     

Role of mutations in DNA gyrase genes in ciprofloxacin resistance of Pseudomonas aeruginosa susceptible or resistant to imipenem

In Pseudomonas aeruginosa, resistance to imipenem is mainly related to a lack of protein OprD and resistance to fluoroquinolones is mainly related to alterations in DNA gyrase. However, strains cross resistant to fluoroquinolones and imipenem have been selected in vitro and in vivo with fluoroquinolones. We investigated the mechanisms of resistance to fluoroquinolones in 30 clinical strains of P. aeruginosa resistant to ciprofloxacin (mean MIC, >8 micrograms/ml), 20 of which were also resistant to imipenem (mean MIC, >16 micrograms/ml). By immunoblotting, OprD levels were markedly decreased in all of the imipenem-resistant strains. Plasmids carrying the wild-type gyrA gene (pPAW207) or gyrB gene (pPBW801) of Escherichia coli were introduced into each strain by transformation. MICs of imipenem did not change after transformation, whereas those of ciprofloxacin and sparfloxacin dramatically decreased (25- to 70-fold) for all of the strains. For 28 of them (8 susceptible and 20 resistant to imipenem), complementation was obtained with pPAW207 but not with pPBW801. After complementation, the geometric mean MICs of ciprofloxacin and sparfloxacin (MICs of 0.3 microgram/ml and 0.5 microgram/ml, respectively) were as low as those for wild-type strains. Complementation was obtained only with pPBW801 for one strain and with pPAW207 and pPBW801 for one strain highly resistant to fluoroquinolones. These results demonstrate that in clinical practice, gyrA mutations are the major mechanism of resistance to fluoroquinolones even in the strains of P. aeruginosa resistant to imipenem and lacking OprD, concomitant resistance to these drugs being the result of the addition of at least two independent mechanisms.     

Characterization of three-dimensional open dielectric structuresusing the finite-difference time-domain method

Millimeter and submillimeter wave three-dimensional (3-D) open dielectric structures are characterized using the finite-difference time-domain (FDTD) technique. The use of FDTD method allows for the accurate characterization of these components in a very wide frequency range. The first structure characterized through FDTD for validation purposes is a mm-wave image guide coupler. The derived theoretical results for this structure are compared to experimental data and show good agreement. Following this validation, a sub-mm wave transition from a strip-ridge line to a layered ridge dielectric waveguide (LRDW) in open environment is analyzed, and the effects of parasitic radiation on electrical performance are studied. The transition is found to be very efficient over a wide sub-mm frequency band which makes it useful for a variety of applications. In addition to the transition, a sub-mm wave distributed directional coupler made of the LRDW is extensively studied using the FDTD method as an analysis tool. Furthermore, an iterative procedure based on the FDTD models is used to design a 3-dB coupler with a center frequency of 650 GHz and negligible radiation loss. This successful design shows that the FDTD technique can be used not only as an analysis method, but also as a design tool to provide designs which take into account all high frequency parasitic effects     

Design of optimum gain pyramidal horn with improved formulas using particle swarm optimization

In this article, a new method to design an optimum gain horn antenna is presented. This method is based on improving existing design equations along with the use of particle swarm optimization technique. The obtained results are more accurate than those available in the literature since no path length error approximation is involved. Improved horn dimensions, for different 15 designs, are obtained which give the desired gain almost exactly. © 2007 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2007.