Almost f-maps and almost f-rings

In the beginning of the eighties, Buskes and Holland proved that any archimedean almost f-ring is commutative. One decade later, Steinberg showed that if G and H are ? with H archimedean, then any positive bilinear map G × G ${{\begin{array}{ll} B \\ \rightarrow \end{array}}}$ H such that ${x \wedge y = 0}$ implies B(x, y) = 0 is symmetric. At first sight, the Steinberg Theorem might seem to be a considerable generalization of the Buskes and Holland result. It turns out, surprisingly enough, that these two results are equivalent. The main purpose of this paper is to establish this equivalence. A second objective is to apply the aforementioned Steinberg Theorem to prove that if R is an f-ring with a unit element e and S is an archimedean f-ring, then an ?-homomorphism R ${{{\begin{array}{ll} h \\\rightarrow \end{array}}}}$ S is a ring homomorphism if and only if h(e) is idempotent in S. This extends a well-known result by Huijsmans and de Pagter, who obtained the same conclusion for semiprime f-algebras.     

Fast, sensitive and cost-effective detection of nerve agents in the gas phase using a portable instrument and an electrochemical biosensor

The nerve agents are chemical warfare agents known to be used during terrorist attacks. An inexpensive and portable system to be used by first responders and military personnel is of interest owing to the continuing threat of possible terrorist attacks. Amperometric biosensors based on cholinesterase inhibition show such potentialities. In this work butyrylcholinesterase was immobilized onto screen-printed electrodes modified with Prussian blue and the nerve agent detection was performed by measuring the residual activity of enzyme. The optimized biosensor was tested with sarin and VX standard solutions, showing detection limits of 12 and 14 ppb (10% of inhibition), respectively. The enzymatic inhibition was also obtained by exposing the biosensors to sarin in gas phase. Two different concentrations of sarin gas (0.1 and 0.5 mg m⁻³) at different incubation times (from 30 s up to 10 min) were tested. It is possible to detect sarin at a concentration of 0.1 mg m⁻³ with 30-s incubation time, with a degree of inhibition of 34%, which match the legal limits (immediate danger to life and health).     

Propagation of S-wave in a non-homogeneous anisotropic incompressible and initially stressed medium under influence of gravity field

In this paper, propagation of shear waves in a non-homogeneous anisotropic incompressible, gravity field and initially stressed medium is studied. Analytical analysis reveals that the velocity of propagation of the shear waves depends upon the direction of propagation, the anisotropy, gravity field, non-homogeneity of the medium, and the initial stress. The frequency equation that determines the velocity of the shear wave has been obtained. The dispersion equations have been obtained and investigated for different cases. A comparison is made with the results predicted by Abd-Alla et al. [22] in the absence of initial stress and gravity field. The results obtained are discussed and presented graphically.     

Adsorptive properties of X zeolites modified by transition metal cation exchange

The ionic exchange of the NaX zeolite by Ni²⁺ and Cr³⁺ cations was progressively driven and studied by adsorption of nitrogen and carbon dioxide. For each cation-exchanged X zeolite sample, the development of characteristics such as profile of isotherms, RI criterion, isosteric adsorption heat and microporous volume using both the Dubinin–Radushkevich (DR) equation and the t-plot, was followed through the nitrogen adsorption. Results show that the cationic exchange process, in the case of Cr³⁺ introduced at middle degree, is accompanied by a textural damage for Cr(x)X, in contrast to Ni²⁺-exchanged X zeolites. This degradation occurs without significant presence of mesopores, because the RI criterion values were found to be much lower than 2.2. The CO₂ adsorption isotherms were measured at intervals of 30 K from 273 K and the equilibrium pressures ranged from 0.5 to 600 Torr. The experimental data were correlated by the Toth model. The associated three adjustable parameters were estimated by nonlinear least-squares analysis. The effect of temperature on the model parameters and the Henry’s law slope, K _H , represented by the product of Toth parameters, are discussed.     

Scheduling with uncertainties on new computing platforms

New distributed computing platforms (grids) are based on interconnections of a large number of processing elements. A most important issue for their effective utilization is the optimal use of resources through proper task scheduling. It consists of allocating the tasks of a parallel program to processors on the platform and to determine at what time the tasks will start their execution. As data may be subject to uncertainties or disturbances, it is practically impossible to precisely predict the input parameters of the task scheduling problem.     

Dirichlet-to-Neumann semigroup acts as a magnifying glass

The first aim of this paper is to illustrate numerically that the Dirichlet-to-Neumann semigroup represented by P. Lax acts as a magnifying glass. In this perspective, we used the finite element method for discretizing of the correspondent boundary dynamical system using the implicit and explicit Euler schemes. We prove by using the Chernoff’s Theorem that the implicit and explicit Euler methods converge to the exact solution and we use the (P1)-finite elements to illustrate this convergence through a FreeFem++ implementation which provides a movie available online. In the Dirichlet-to-Neumann semigroup represented by P. Lax the conductivity \(\gamma \) is the identity matrix \(I_n\) , but for a different conductivity \(\gamma \) , the authors of Cornean et al. (J Inverse Ill-posed Prob 12:111–134, 2006) supplied an estimation of the operator norm of the difference between the Dirichlet-to-Neumann operator \(\Lambda _\gamma \) and \(\Lambda _1\) , when \(\gamma =\beta I_n\) and \(\beta =1\) near the boundary \(\partial \Omega \) (see Lemma 2.1). We will use this result to estimate the accuracy between the correspondent Dirichlet-to-Neumann semigroup and the Lax semigroup, for \(f\in H^{1/2}(\partial \Omega )\) .     

Uranium(VI) and Thorium(IV) Adsorption Studies on Chelating Resin Containing Pentaethylenehexamine as a Functional Group

A new chelating resin (glycidyl methacrylate/divinylbenzene/pentaethylenehexamine (GMA/DVB/PEHA)) for uranium(VI) and thorium(IV) has been developed by functionalizing GMA/DVB with PEHA. The adsorption of U(VI) and Th(IV) ions onto the functionalized GMA/DVB/PEHA were investigated as a function of pH value, contact time, and temperature using batch adsorption technique. The results showed that U(VI) and Th(IV) adsorption onto GMA/DVB/PEHA was strongly dependent on pH. Kinetic studies revealed that the adsorption process achieved equilibrium within 15 and 90 minutes for Th(IV) and U(VI), respectively, and followed a pseudo-second-order rate equation. The isothermal data correlated with the Langmuir model better than the Freundlich model. Thermodynamic data indicated the spontaneous and endothermic nature of the process. The maximum adsorption capacity of U(VI) and Th(IV) were found to be 114 and 78 mg/g, respectively. Quantitative recovery of uranium and thorium were achieved by desorbing the loaded GMA/DVB/PEHA with 0.5 M HNO₃      

Coupling of Ultrafast LC with Mass Spectrometry by DESI

Recently we reported a desorption electrospray ionization (DESI) interface to combine liquid chromatography (LC) with mass spectrometry (MS) using a new LC eluent splitting strategy through a tiny orifice on LC capillary tube [J. Am. Soc. Mass Spectrom. 25, 286 (2014)]. The interface introduces negligible dead volume and back pressure, thereby allowing “near real-time” MS detection, fast LC elution, and online MS-directed purification. This study further evaluates the LC/DESI-MS performance with focus of using ultra-fast LC. Using a monolithic C₁₈ column, metabolites in urine can be separated within 1.6 min and can be online collected for subsequent structure elucidation (e.g., by NMR, UV, IR) in a recovery yield up to 99%. Using a spray solvent with alkaline pH, negative ions could be directly generated for acidic analytes (e.g., ibuprofen) in acidic LC eluent by DESI, offering a novel protocol to realize “wrong-way around” ionization for LC/MS analysis. In addition, DESI-MS is found to be compatible with ultra-performance liquid chromatography (UPLC) for the first time.      

Development of a Novel Electrochemical Sensor Based on Functionalized Carbon Black for the Detection of Guanine Released from DNA Hydrolysis

In this work, we reported a new strategy based on DNA strands hydrolysis in combination with the employment of functionalized carbon black modified screen-printed electrode (f-CB/SPE) for guanine detection. Using glass microbeads as a solid substrate of ssDNA probe fixation, and under appropriate conditions of temperature, time, and hydrochloric acid concentration, DNA hydrolysis has been successfully used to release the guanine, allowing its oxidation at f-CB/SPE using differential pulse voltammetry. The selectivity was successfully tested with a non-complementary sequence, and a detection limit of 0.7 nM of the target DNA has been reached.     

Theoretical study of the νO–H IR spectra for the hydrogen bond dimers from the polarized spectra of glutaric and 1-naphthoic acid crystals: Fermi resonances effects

A full quantum theoretical model is proposed to study the ν_O–H experimental IR line shapes of polarized crystalline glutaric and 1-naphthoic acid dimer crystals at room and liquid nitrogen temperatures. This work is an application of a previous model [M. E-A. Benmalti, D. Chamma, P. Blaise, and O. Henri-Rousseau, J. Mol. Struct. 785 (2006) 27–31] by accounting for Fermi resonances. The approach is dealing with the strong anharmonic coupling, Davydov coupling, multiple Fermi resonances between the first harmonics of some bending modes and the first excited state of the symmetric combination of the two ν_O–H modes and the quantum direct and indirect relaxation.Numerical results show that mixing of all these effects allows to reproduce satisfactorily the main features of the experimental IR line shapes of crystalline hydrogenated and deuterated glutaric and 1-naphthoic acid crystals and are expected to provide efficient of Fermi resonances effects.