A statistical model for unwarping of 1-D electrophoresis gels

A statistical model is proposed which relates density profiles in 1-D electrophoresis gels, such as those produced by pulsed-field gel electrophoresis (PFGE), to databases of profiles of known genotypes. The warp in each gel lane is described by a trend that is linear in its parameters plus a first-order autoregressive process, and density differences are modelled by a mixture of two normal distributions. Maximum likelihood estimates are computed efficiently by a recursive algorithm that alternates between dynamic time warping to align individual lanes and generalised-least-squares regression to ensure that the warp is smooth between lanes. The method, illustrated using PFGE of Escherichia coli O157 strains, automatically unwarps and classifies gel lanes, and facilitates manual identification of new genotypes.     

Electric-Field-Induced Organic Transformations

Experiments showed that the existence of electric fields in non-redox processes may alter the catalytic activity, rate enhancement, and selection of organic reactions. It is expected that the interaction between electric fields and chemical reactions will create new avenues for producing materials with desired properties in several chemical disciplines, including synthetic organic chemistry, catalysis, nanotechnology, membrane technology, and enzyme catalysis. Specifically, in this review, we discuss the elegant experimental investigations carried out using the scanning tunneling microscope, the interfacial electric field, and designed local electric fields. The results of these studies are remarkable, leading to new information on the function of electric fields in controlling chemical reactivity and selectivity in different reactions and offering a glimpse of the great potential of electrostatic fields. This article not only presents the core concepts of field-induced chemical transformations but also illustrates the potential use of electric field catalysis in chemistry and other fields.     

Estimation of power spectral density from laser Doppler data via linear interpolation and deconvolution

Spectral estimation of irregularly sampled velocity data issued from Laser Doppler Anemometry measurements is considered in this paper. A new method is proposed based on linear interpolation followed by a deconvolution procedure. In this method, the analytic expression of the autocorrelation function of the interpolated data is expressed as a linear function of the autocorrelation function of the data to be estimated. For the analysis of both simulated and experimental data, the results of the proposed method is compared with the one of the reference methods in LDA: refinement of autocorrelation function of sample-and-hold interpolated signal method given by Nobach et al. (Exp Fluids 24:499–509, 1998), refinement of power spectral density of sample-and-hold interpolated signal method given by Simon and Fitzpatrick (Exp Fluids 37:272–280, 2004) and fuzzy slotting technique with local normalization and weighting algorithm given by Nobach (Exp Fluids 32:337–345, 2002). Based on these results, it is concluded that the performances of the proposed method are better than the one of the other methods, especially for what concerns bias and variance.     

Determination of rifaximin in rat serum by ionic liquid based dispersive liquid-liquid microextraction combined with RP-HPLC

An efficient and environmental friendly ionic liquid based dispersive liquid-liquid microextraction procedure was optimized for determination of rifaximin in rat serum by reverse phase high-performance liquid chromatography. The effect of ionic liquids, dispersive solvents, extractant/disperser ratio, and salt concentrations on sample recovery and enrichment factors were studied. Among the five ionic liquids studied in the present investigation, 1-butyl-3-methylimidazolium hexafluorophosphate was found to be most effective for extraction of rifaximin. The recovery was found to be more than 98% using 1-butyl-3-methylimidazolium hexafluorophosphate and methanol as extraction and dispersive solvents, at an extractant/disperser ratio of 0.43. The recovery was further enhanced to 99.5% by the addition of 5.0% NaCl solution. A threefold enhancement in detection limit was achieved when compared to protein precipitation. The ionic liquid containing the extracted rifaximin was directly injected into HPLC system. The linear relationship was observed in the range of 0.03-10.0 μg/mL with the correlation coefficient (r(2) ) 0.9998. Limits of detection and quantification were found to be 0.01 and 0.03 μg/mL, respectively. The relative standard deviation was 2.5%. The method was validated and applied to study pharmacokinetics of rifaxmin in rat serum.     

Hugoniot–Maslov chains of a shock wave in conservation law with polynomial flow

In this paper we give a theoretical foundation to the asymptotical development proposed by V. P. Maslov for shock type singular solutions of conservations laws, in the framework of Colombeau theory of generalized functions. Indeed, operating with Colombeau differential algebra of simplified generalized functions, we proof that Hugoniot–Maslov chains are necessary conditions for the existence of shock waves in conservation laws with polynomial flows. As a particular case, these equations include the Hugoniot–Maslov chains for shock waves in the Hopf equation. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Biocorrosion and biocompatibility of Zr–Cu–Fe–Al bulk metallic glasses

Owing to their unique chemo‐physical and structural characteristics, amorphous bulk metallic glasses (BMGs) are of great demand for fabrication of variety of advanced and innovative products including surgical and biomedical tools and devices. In this study, a series of Ni‐free Zr‐based BMGs in Zr–Cu–Fe–Al system are fabricated using copper‐mold casting technique, and their biocorrosion and biocompatibility are evaluated with respect to their corrosion behavior in the phosphate buffered saline (pH = 7.4) solution. Anodic polarization curves, scanning electron microscopy combined with energy‐dispersive X‐ray, and wettability analyses are conducted to characterize the surfaces of BMG samples. The biocompatibility of the BMG and control samples is studied by comparing cell–substrate interactions among different samples. It is found that Zr₆₀Cu₂₀Fe₁₀Al₁₀ displays a higher passive region compared with that of Zr₆₀Cu_22.5Fe_7.5Al₁₀, but both BMGs exhibit lower corrosion resistance compared with Ti–6Al–4V alloy. By addition of titanium to Zr–Cu–Fe–Al system (Zr₆₀Ti₆Cu₁₉Fe₅Al₁₀), a significant increase in the passive region of the polarization curve is detected. The cell culture experiments reveal that the number of attached and grown cells is significantly higher on the surface of the treated BMGs as compared with Ti–6Al–4V substrates and the culture plate as controls. There is no noticeable difference in cellular morphology among the BMG samples, and no cytotoxicity is detected. We speculate that the interaction of water molecules and matrix proteins with the surfaces of BMGs plays an important role in cell–substrate interactions and improved cell response. Copyright © 2013 John Wiley & Sons, Ltd.     

Selective Sensing Characteristics of Ca Doped BeO Nano-sized Tube toward H20 and NH3

By means of density functional calculations, the structural and electronic properties of chemical modification of pristine and Ca-doped BeO nanotubes were investigated with NH3 and H20 molecules. It was found that the NH3 and H20 molecules can be adsorbed on the Be atom of the tube sidewall with the adsorption energies of about 36.1 and 39.0 kcal/mol, respectively. Density of states analysis shows that the electronic properties of the BeONT are slightly changed after the adsorption processes. Substitution of a Be atom in the tube surface with a Ca atom increases the adsorption energies by about 7.4 and 14.7 kcal/mol for NH3 and H20, respectively. Unlike the pristine tube, the electronic properties of Ca-doped BeONT are sensitive to NH3 and H20 molecules. Also, the Ca-doped tube is much more sensitive to H20 molecule than NH3 one.     

Hugoniot–Maslov Chain for Shock Waves in Buckley–Leverett Equations

Mathematical Notes - In this paper, we apply the asymptotic method developed by V. P. Maslov [1] to obtain the approximated shock-type solutions of the generalized Riemann problem (GRP) to the...     

Electrodeposition of Silver Vanadate Films: A Tale of Two Polymorphs

Two polymorphs of AgVO₃, namely the α- and β- forms, were prepared and their physical, structural, optical, electrochemical, and photoelectrochemical characteristics were compared using a battery of experimental and theoretical tools. A two-step method, previously developed in the our laboratory for the electrodeposition of inorganic semiconductor films, was applied to the electrosynthesis of silver vanadate (AgVO₃) films on transparent, conducting oxide surfaces. In the first step, silver was cathodically deposited from a non-aqueous bath containing silver nitrate. In the second step, the silver film was anodically stripped in an aqueous medium containing ammonium metavanadate. The anodically generated silver ions at the interface underwent a precipitation reaction with the vanadate species to generate the desired product in situ. Each of these steps were mechanistically corroborated via the use of electrochemical quartz crystal microgravimetry, used in conjunction with voltammetry and coulometry. As-deposited films were crystalline and showed p-type semiconductor behavior. Theoretical insights are provided for the electronic origin of the α→β phase transformation in AgVO₃ and the disparate optical band gaps of the two polymorphs. Finally, implications for the application of this material in solar cells are provided.