On summability of nonlinear mappings: a new approach

The main goal of this paper is to characterize arbitrary nonlinear (non-multilinear) mappings ${f:X_{1}\times\cdots\times X_{n}\rightarrow Y}$ between Banach spaces that satisfy a quite natural Pietsch Domination-type theorem around a given point ${(a_{1},\ldots,a_{n})\in X_{1}\times\cdots\times X_{n}}$ . As a consequence of our approach a notion of weighted summability arises naturally, which may be an interesting topic for further investigation.     

Optimizing the DMFC operating conditions using a response surface method

The power density of a Direct Methanol Fuel Cell (DMFC) as a function of temperature, methanol concentration, air flow rate, methanol flow rate and air relative humidity was studied using a Response Surface Methodology (RSM). For a DMFC equipped with a membrane of Nafion 112, it was observed that only the temperature, methanol concentration and air flow rate were relevant factors or operating variables. A new design of experiments was done for a narrower range of these variables and the operating values that optimise the power density were obtained using the software JMP 7.0 (SAS). The predicted power density values were in agreement with the experimental results obtained for the optimized operating conditions. Then, the RSM was applied to membranes with different thicknesses, Nafion 112, Nafion 1135 and Nafion 117, and as a function of the temperature and methanol concentration. The DMFC was characterized for the open circuit voltage (OCV), methanol crossover at the OC, power density and global efficiency. The membrane showing the best compromise between power density and efficiency was Nafion 117.     

Spinless Duffin-Kemmer-Petiau Oscillator in a Galilean Non-commutative Phase Space

We examine Galilei-invariant linear wave equations in a non-commutative phase space. Specifically, we establish and solve the Galilean covariant Duffin-Kemmer-Petiau equation for spin-0 fields in a harmonic oscillator potential. We obtain these wave equations with a Galilean covariant approach, based on a (4+1)-dimensional manifold with light-cone coordinates followed by a reduction to a (3+1)-dimensional spacetime. We find the exact wave functions and their energy levels, and we examine the effects of non-commutativity.     

Photorefractive Fourier transform profilometer for the measurement of 3-D object shapes

In the present work dynamic moiré-like fringe patterns, produced by photorefraction with low spatial frequencies, applied for profile determination of small objects is proposed. Basically, a Fourier transform profilometry technique is developed for an automated profile determination. This means, as far as we know, a new experimental procedure that exploits the real time holographic two wave mixing in Bi₁₂TiO₂₀ crystal sample. Besides, the mainly advantages of this procedure are, comparatively to the classical fringe projection method using the Michelson interferometer, best fringe pattern contrast, less speckle noise, absence of noises produced by spurious reflections and, the most significant, a pure sinusoidal shape obtained by dynamic holographic moiré-like process using photorefraction.     

Fourth virial coefficients of asymmetric nonadditive hard-disk mixtures

The fourth virial coefficient of asymmetric nonadditive binary mixtures of hard disks is computed with a standard Monte Carlo method. Wide ranges of size ratio (0.05 ≤ q ≤ 0.95) and nonadditivity (-0.5 ≤ Δ ≤ 0.5) are covered. A comparison is made between the numerical results and those that follow from some theoretical developments. The possible use of these data in the derivation of new equations of state for these mixtures is illustrated by considering a rescaled virial expansion truncated to fourth order. The numerical results obtained using this equation of state are compared with Monte Carlo simulation data in the case of a size ratio q = 0.7 and two nonadditivities Δ = ±0.2.     

Volumetric Properties of the Binary System Trihexyltetradecylphosphonium Bromide (CYPHOS IL 102) + N,N-Dimethylformamide (DMF) at Temperatures from T=293.15 to 313.15 K at Atmospheric Pressure

Volumetric properties for the trihexyltetradecylphosphonium bromide (CYPHOS IL 102) + N,N-dimethylformamide (DMF) binary system were determined at temperatures from T=293.15 to 313.15?K and ambient pressure (p=0.7 atm). Densities were measured by means of a vibrating tube densimeter (VTD). These measurements covered the full range of compositions along with the pure compounds; expansion coefficients, excess molar volumes, and partial molar volumes were calculated from the experimental densities. Excess molar volumes were fitted to a Redlich?CKister type equation. The excess molar volumes exhibit negative deviations from ideal behavior.     

Structural Aspects of Copper‐Mediated Atom Transfer Radical Polymerization with a Novel Tetradentate Bisguanidine Ligand

This contribution reports the synthesis of the novel tetradentate bisguanidine ligand 2′,2′‐[ethane‐1, 2‐diylbis(methylazanediyl)]bis(ethane‐2, 1‐diyl)bis(1, 1, 3, 3‐tetramethylguanidine) ( L1 , TMG₂dmtrien), which combines two weak amine and two strong guanidine donor functions. Two new copper(II) complexes were isolated and structurally characterized as complexes [Cu(TMG₂dmtrien)][Br]₂ · 3MeCN ( C1 [Br]₂ · 3MeCN) and [Cu(TMG₂dmtrien)][Cl]₂ · 3MeCN ( C2 [Cl]₂ · 3MeCN). The cations C1 and C2 [Cu(TMG₂dmtrien)]²⁺ show a square‐planar coordination environment and are chiral with both enantiomers being observed in the unit cell. We investigated the application of L1 in copper‐mediated styrene ATRP. L1 shows with CuBr and PEBr as initiator a high polymerization activity according to the polymerization rate. First order kinetics confirm the living character of the polymerization. However, the deviation of molecular weights from theoretical molecular weights and the broad molecular weight distributions hint for a low controlled ATRP. The ATRP with further copper(I) salts {CuCl, [Cu(MeCN)₄]BF₄ and [Cu(MeCN)₄]PF₆} and PECl and PEBr as initiators were investigated as well. Herein the use of [Cu(MeCN)₄]PF₆ with PECl led to promising results.     

Determination of quinolones in milk samples using a combination of magnetic solid-phase extraction and capillary electrophoresis

A magnetic solid-phase extraction (MSPE) method combined with capillary electrophoresis for the simultaneous determination of seven quinolones (QNs) (danofloxacin, ciprofloxacin, marbofloxacin, enrofloxacin, difloxacin, oxolinic acid, and flumequine), using (S)-(+)-6-methoxy-α-methyl-2-naphthaleneacetic acid as internal standard, in milk samples was developed. The variables involved in the preconcentration magnetic procedure were: the composition of the magnetic support composition, the sample pH, and the weight of magnetic adsorbent used. The variables were optimized using a simplex-lattice design. Different magnetite covered with octyl-phenyl silica adsorbents were synthesized by varying the molar ratio of phenyltrimethylsilane and octyltrimethoxysilane; the solids were evaluated for QN preconcentration. Under optimal conditions, a linear range was obtained from 27 to 1000 μg L(-1) with limits of detection ranging from 9 to 12 μg L(-1) for the seven QNs. The absolute recoveries of the seven QNs at three different spiked levels (40, 150, and 400 μg L(-1) ) ranged from 74% to 98% with a relative standard deviation less than 10% in all cases. The proposed method was applied to analyze 20 whole milk samples of different brands. All samples were positive for the presence of QN residues; in some cases, extract dilution was required. The concentrations found are in the range from 31.1 to 5047.3 μg L(-1) . Marbofloxacin was the most frequently found. The method proposed offers advantages in terms of simplicity, sensitivity, efficiency, cost, and analysis time making it an alternative for the analysis of QNs in whole milk samples.     

Characterization of Polyurethanes from Vegetable Oils by TG/DTG,DMA and FT-IR

Summary: Given the demand for renewable resources by industries and the promising potential of vegetable oils for this purpose, the current study aims to evaluate the properties of polyurethanes (PUs) obtained from linseed (Linum usitatissimun L.) oil (PULO) and passion fruit (Passiflora edulis Sims f. flavicarpa Degener) oil (PUPFO), by thermogravimetry (TG), derivative thermogravimetry (DTG), dynamic mechanical analysis (DMA) and Fourier transform infrared (FT-IR). The results showed that PULO is more thermally stable than PUPFO, suggesting that the first presents more urethane linkages. The DMA analysis showed that both prepared PUs have uneven porosity, causing the loss of the elastic plateau. It was found as well that PUPFO exhibits a higher value of glass transition temperature (T_g), signifying that it seems to be more crosslinked than PULO. The analysis by FT-IR showed that the curing reaction of PUs was successful.     

Electrochemical Determination of Inorganic Contaminants in Automotive Fuels

This article critically reviews the electroanalytical methods developed for the determination of inorganic contaminants in automotive fuels. Topics include the methods applied to the analysis of liquid biofuels and liquid fossil fuels for which different strategies were developed based on analytes and sample matrices. Special attention is given to electrodes, detection techniques, and sample preparation protocols (when required). Analytes include anions such as chloride, sulfate and phosphate, and mainly metallic species such as sodium, potassium, magnesium, calcium, cadmium, copper, iron, lead, manganese, mercury, nickel, platinum, tin, vanadium, and zinc. Suggestions for future research are also presented.