Large Eddy Simulation and Extended Dynamic Mode Decomposition of Flow-Flame Interaction in a Lean Premixed Low Swirl Stabilized Flame

In this paper, numerical studies are reported on the effect of flow-flame interaction at large and medium scales and its impact on flame stabilization in a lean premixed low swirl stabilized methane/air flame. The numerical simulations are based on a large eddy simulation (LES) approach with a three-scalar flamelet model with equations for mixture fraction and fuel mass fraction and the level-set G-equation to account respectively for stratification of the mixture, fuel leakage at the trailing edge of the flame, and tracking of the flame front. Distinct frequencies, associated with the flame stabilization process, are identified from point data of LES in the outer and inner shear layers of the burner induced flow field. To understand the effect of the spatial structures related to the observed flow frequencies, a dynamic mode decomposition (DMD) is performed. Based on the analysis of LES data, frequency specific coherent flow structures are extracted along with associated flame structures through an extended version of DMD. The inner shear layer generated vortices are associated with recurring frequency specific coherent structures of both flow and flame and contribute to the flame stabilization in the outer regions of the flow.     

Flexure analysis of unsymmetric orthotropic beams with an interlayer

This paper presents a layer-wise stress and deformation analysis of a three-layer beam configuration consisting of two dissimilar orthotropic adherends of different thicknesses that are joined together by a deformable interlayer of finite thickness. Analytical solutions for the case of three-point flexure loading are presented for both compressible and incompressible interlayers. Parametric analysis reveals the influences of asymmetry of moduli and adherend thicknesses, interlayer thickness, and overhang of the beams on the beam compliance. Analytical predictions of beam compliance show very good agreement with finite element results. Experimental measurements of compliance of various unsymmetric beams consisting of aluminum adherends separated by a rubber interlayer were performed in order to validate the analysis. Excellent agreement between measured and predicted compliance values was observed.     

Optimization of peak area precision of a GC–MS drug screening method using a nonparametric sign test

Accreditation and Quality Assurance - The optimization of a number of gas chromatography–mass spectrometry (GC–MS) parameters in order to improve peak area precision through...     

Biaxially Oriented Polypropylene (BOPP) Surface Modification by Nitrogen Atmospheric Pressure Glow Discharge (APGD) and by Air Corona

We compare two surface treatments of biaxially-oriented polypropylene (BOPP), which are carried out in the same dielectric barrier discharge (DBD) apparatus, namely air corona, and N₂ atmospheric pressure glow discharge (APGD). Changes in the surface energy and chemistry are investigated by contact angle measurements, by X-ray photoelectron spectroscopy (XPS) and by attenuated total reflectance infrared spectroscopy (ATR-FTIR). It is shown that N₂ APGD treatment leads to a higher surface energy than air corona treatment, and to the formation of mostly amine, amide, and hydroxyl functional groups at the polypropylene surface. Finally, hydrophobic recovery of the treated film is studied; for both treatment types, the increased surface energy is found to decay in a similar manner with increasing storage time after treatment.     

Multienzyme electrochemical array sensor for determination of phenols and pesticides

The screen-printed four-electrode system was used as the amperometric transducer for determination of phenols and pesticides using immobilised tyrosinase, peroxidase, acetylcholinesterase and butyrylcholinesterase. Acetylthiocholine chloride was chosen as substrate for cholinesterases to measure inhibition by pesticides, hydrogen peroxide served as co-substrate for peroxidase to measure phenols. The compatibility of hydrolases and oxidoreductases working in the same array was studied. The detection of p-cresol, catechol and phenol as well as of pesticides including carbaryl, heptenophos and fenitrothion was carried out in flow-through and steady state arrangements. In addition, the effects of heavy metals (Cu²⁺, Cd²⁺, Fe³⁺), fluoride (NaF), benzene and dimethylsulphoxide on cholinesterase activities were evaluated. It was demonstrated that electrodes modified with hydrolases and oxidoreductases can function in the same array.The achieved R.S.D. values obtained for the flow system were below 4% for the same sensor and less than 10% within a group of five sensors. For the steady state system, R.S.D.s were approximately twice higher. One assay was completed in less than 6 min. The limit of detection for catechol using tyrosinase was equal to 0.35 and 1.7 μM in the flow and steady state systems, respectively. On the contrary, lower limits of detection for pesticides were achieved in the steady state system—carbaryl 26 nM, heptenophos 14 nM and fenitrothion 0.58 μM.     

The immune diversity in a test tube--non-immunised antibody libraries and functional variability in defined protein scaffolds

Technologies to develop and evolve the function of proteins and, in particular, antibodies have developed rapidly since the introduction of phage display. Importantly, it has become possible to identify molecules with binding properties that cannot be found by other means. A range of different approaches to create general libraries that are useful for the selection of such molecules specific for essentially any kind of target have emerged. We herein review some of the most prominent approaches in the field and in particular discuss specific features related to the development of antibody libraries based on single antibody framework scaffolds. This approach not only permits identification of a range of specific binders, but also facilitates further evolution of initially derived molecules into molecules with optimised functions.     

Structural and functional models of the active site of zinc phosphotriesterase

In an attempt to prepare structural and functional models for the active site of the hydrolytic enzyme zinc phosphotriesterase, five new zinc complexes of the ligands 2,6-bis[N-(N-(carboxylmethyl)-N-((1-methylimidazol)methyl)amine)methyl]-4-methylphenolate (BCIMP) and the corresponding asymmetric ligand 2-(N-isopropyl-N-((1-methylimidazolyl)methyl)aminomethyl)-6-(N-carboxylmethyl-N-((1-methylimidazolyl)methyl)aminomethyl)-4-methylphenol (ICIMP) have been synthesized, viz. Na[Zn(2)(BCIMP)Ac(2)] (1), [Zn(2)(BCIMP)(Ph(2)Ac)] (2), [Zn(2)(ICIMP)Ac(2)] (3), [Zn(4)(ICIMP)(2)(Me(3)Ac)(2)][ClO(4)](2) (4), and [Zn(4)(ICIMP)(2)(Ph(2)Ac)(2)][ClO(4)](2) (5). The X-ray structure of complex 5 has been determined and reveals that the complex is a dimer of dimers in the solid state, which in solution dissociates to potent structural models. Studies using NMR show that only one carboxylate coligand bridges the dizinc units in the case of diphenyl acetate and pivalate, while the steric bulk of acetate is sufficiently small to permit the coordination of two acetates/dizinc unit. Functional studies involving the hydrolysis/transesterification of 2-hydroxypropyl p-nitrophenyl phosphate (HPNP) show that the complex with ICIMP (compound 5) has a significantly higher rate of catalysis than the BCIMP complex (compound 2). This is attributed to the vacant/labile coordination site that is available in the ICIMP complex but not the BCIMP complex.