Defect‐induced ferrimagnetism in the half‐metallic Co2CrAl and Co2CrSi compounds

Co₂CrAl and Co₂CrSi are amongst the most studied Heusler alloys due to their half‐metallic character. These compounds are also well‐known to present ferromagnetism with high Curie temperatures. We show using first‐principles calculations that the creation of Cr antisites (Cr atoms at the Co sites) induces ferrimagnetism in these compounds without destroying the half‐metallic character of these alloys. The reduction of the total spin moment causes lower external fields and thus smaller energy losses in realistic magnetoelectronic, also known as spintronic, devices. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Experimental investigation of impinging jet arrays

We report on measurements of the velocity field and turbulence fluctuations in a hexagonal array of circular jets, impinging normally on a plane wall, using particle image velocimetry (PIV). Results for mean velocity and turbulent stresses are presented in various horizontal and vertical planes. From the measurements, we have identified some major features of impinging jet arrays and we discuss their mutual interaction, collision on the plate, and consequent backwash, which generate recirculating motion between the jets. The length of the jet core, the production of turbulence kinetic energy, and the model of the exhaust mechanisms for spent fluid are also discussed. The measurements indicated that the interaction between the self-induced cross flow and the wall jets resulted in the formation of a system of horseshoe-type vortices that circumscribe the outer jets of the array. The instantaneous snapshots of the velocity field reveal some interesting features of the flow dynamics, indicating a breakdown of some of the jets before reaching the plate, which may have consequences on the distribution of the instantaneous heat transfer.List of symbols D_m Nozzle diameter in multiple jet array nozzle plate (m) - D_s Pipe diameter in single jet rig (m) - H Distance between nozzle and impingement plate (m) - k Turbulent kinetic energy (m²/s²) - L Pipe length (m) - P_k Production of turbulent kinetic energy (m²/s³) - P_uu , P_vv Normal components of P_k (m²/s³) - P_uv Shear component of P_k (m²/s³) - s Pitch (m) - U_bulk Surface-averaged exit velocity (single jet) (m/s) - U_CL Center line jet exit velocity (jet array), m/s - u, v Mean velocity components in x and y directions (m/s) - u, v, w Instantaneous velocity in x, y, and z directions (m/s) - u, v, w Velocity fluctuation in x, y, and z directions (m/s) - u², v², w² Reynolds normal stress components (m²/s²) - uv Reynolds shear stress component (m²/s²) - x, z Coordinates parallel to impingement plate (m) - y Coordinate perpendicular to impingement plate (m)     

KALMAN-FILTER-BASED OBSERVER DESIGN AROUND OPTIMAL CONTROL POLICY FOR GAS PIPELINES

Seeking the optimal operating policy by an off-line controller for pipelines carrying natural gas has an inherent state estimation problem associated with deviations from demand forecast. This paper presents a Kalman-filter-based observer for the real-time estimation of deviations from the states previously obtained by an off-line controller optimally, around an expected demand function. The observer is based on the linearized form of the non-linear partial differential equations which are the state space representation of isothermal and unidirectional gas flow through a pipeline. Data for the observer are produced by a dynamic simulator. The simulator and linearized observer equations are solved using an implicit finite element method. The observer has been tested on a pipeline subject to certain deviations from demand forecast. It converge s in a short span of time. © 1997 by John Wiley & Sons, Ltd.     

Nonswellable and swellable ethylene glycol dimethacrylate-acrylic acid copolymer microspheres

In this study, nonswellable and swellable poly(ethylene glycol dimethacrylate/acrylic acid) copolymer microspheres, in the size range of 50–150 μm, were produced by conventional and modified suspension copolymerizations of the respective monomers, i.e., ethyleneglycol dimethacrylate (EGDMA) and acrylic acid (AA) in aqueous media. Poly(vinyl alcohol) and benzoyl peroxide were used as the stabilizer and the initiator. The diluent, i.e., toluene was included in the polymerization recipe of the modified suspension polymerization. The microspheres were characterized by optical microscopy, FTIR, and FTIR-DRS, and potentiometric titrations. Highly crosslinked, transparent, and nonswellable poly(EGDMA/AA) microspheres were obtained with the conventional suspension polymerization procedure. The modified suspension polymerization provided swellable, opaque, and crosslinked copolymer microspheres. Acrylic acid incorporation into the copolymeric microspheres were significantly higher in the modified procedure, relative to the conventional procedure. © 1996 John Wiley & Sons, Inc.     

Evaluation of Antibacterial and Antifungal Effects of Calcium Hydroxide Mixed with Two Different Essential Oils

Background: Calcium hydroxide is a routinely used material for root canal disinfection during root canal treatment. Natural products have great potential in terms of their antibacterial effects. This study aimed to establish an effective alternative intracanal medicament using Origanum dubium (O. dubium) and Mentha spicata (M. spicata) essential oils. Materials and Methods: O. dubium and M. spicata, collected from Lefke, Cyprus, were separately subjected to hydrodistillation. The obtained essential oil compositions were analysed simultaneously by gas chromatography (GC) and gas chromatography/mass spectrometry (GC-MS). The compositions were then divided into groups and mixed with calcium hydroxide at a 1:1 concentration; after that, the pastes were tested on Enterococcus faecalis (E. faecalis) and Candida albicans (C. albicans), which are the most common resistant pathogenic microorganisms in the root canal. The antibacterial activity of the pastes was measured using a disk diffusion assay. Results: The GC and GC-MS analyses revealed that O. dubium and M. spicata had major compositions of carvacrol (75.8%) and carvone (71.3%), respectively. Antimicrobial activity was found to be significantly higher when study groups with O. dubium essential oil were applied to both E. faecalis and C. albicans. The results also show that M. spicata, together with calcium hydroxide, demonstrated a significant antifungal effect on C. albicans when incubated for 72 h. Conclusions: M. spicata was found to be an effective antimicrobial agent on C. albicans, whereas O. dubium was found to be very effective on both E. faecalis and C. albicans. These data demonstrate that these natural essential oils may be promising candidates for alternative intracanal medicament in future routine clinical applications.     

A Highly Selective Poly(thiophene)‐graft‐Poly(methacrylamide) Polymer Modified ITO Electrode for Neuron Specific Enolase Detection in Human Serum

In this study, an impedimetric immunosensor based on polymer poly(thiophene)‐graft‐poly(methacrylamide) polymer (P(Thi‐g‐MAm)) modified indium tin oxide (ITO) electrode is developed for the detection of the Neuron Specific Enolase (NSE) cancer biomarker. First, the P(Thi‐g‐MAm) polymer is synthesized and coated on the ITO electrode by using a spin‐coating technique. P(Thi‐g‐MAm) polymer acts as an immobilization platform for immobilization of NSE‐specific monoclonal antibodies. Anti‐NSE antibodies are utilized as biosensing molecules and they bind to the amino groups of P(Thi‐g‐Mam) polymer via glutaraldehyde cross‐linking. Spin‐coating technique is employed for bioelectrode fabrication and this technique provides a thin and uniform film on the ITO electrode surface. This bioelectrode fabrication technique is simple and it generates a suitable platform for large‐scale loadings of anti‐NSE antibodies. This immunosensor exhibits a wide linear detection range from 0.02 to 4 pg mL^?1 and with an ultralow detection limit of 6.1 fg mL^?1. It reveals a good long‐term stability (after 8 weeks, 78% of its initial activity), an excellent reproducibility (1.29% of relative standard deviation (RSD)), a good repeatability (5.55% of RSD), and a high selectivity. In addition, the developed immunosensor is proposed as a robust diagnostic tool for the clinical detection of NSE and other cancer biomarkers.     

Higgs production in gluon fusion at next-to-next-to-leading order QCD for finite top mass

The inclusive Higgs production cross section from gluon fusion is calculated through NNLO QCD, including its top quark mass dependence. This is achieved through a matching of the 1/M _t expansion of the partonic cross sections to the exact large- $\hat{s}$ limits which are derived from k _T -factorization. The accuracy of this procedure is estimated to be better than 1% for the hadronic cross section. The final result is shown to be within 1% of the commonly used effective theory approach, thus confirming earlier findings.     

Mechanical and lattice dynamical properties of the Re2C compound

In this work, density functional theory calculations on the structural, mechanical, and lattice dynamical properties of Re₂C within ReB₂‐type structure are reported. The generalized gradient approximation has been used for modeling exchange–correlation effects. We have predicted the lattice constants, bulk modulus, bond distances, elastic constants, shear modulus, Young's modulus, Poisson's ratio, hardness, Debye temperature, and sound velocities of this compound. Furthermore, the band structure, phonon dispersion curves and corresponding density of states are computed. The obtained results are in good agreement with the available experimental and other theoretical data. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)