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The present work deals with the numerical simulations of 3D incompressible flow through periodic porous structures, consisting of cubic cells with different strut geometry and structure tilting with respect to the flow direction. Simulation results are obtained for different porosities, while covering a range of Reynolds numbers from laminar-steady flow (Darcy regime) up to the transition to laminar-unsteady flow (moderate Forchheimer regime). These results are post-processed in order to characterize the influence of the periodic porous structures on the flow statistics related to the Darcy-Forchheimer law. Based on this analysis, along with 3D simulation results previously obtained for different random foams, correlations for the Darcy and Forchheimmer permeability coefficients are developed from a theoretical background, being expressed only as functions of the cell geometrical parameters and tortuosity estimation. However, the influences of flow tortuosity and cell orientation on the Darcy coefficient are found to cancel each other. The proposed correlation for the Darcy coefficient performs very well for both periodic and random porous structures, when compared with recent correlations available in the literature. The performance of the correlation proposed for the Forchheimmer coefficient is found to be satisfactory, however, different correlation constants were found for periodic and random structures. The proposed correlation for the Forchheimer permeability coefficient depends on the flow tortuosity inside the porous structure, which must be estimated either through 3D fluid flow simulations or using tortuosity correlations. In this respect, a correlation is proposed for predicting the flow tortuosity inside porous structures, as an alternative for avoiding 3D simulations.

The development of new amine systems for CO2 capture is a topic of high interest because of the limitations current aqueous amine systems have for capturing CO2 at large scale. Having a robust and systematic approach for describing the absorption of CO2 would help accelerating the discovery of high performance amine solvents. In this contribution, a molecular-based equation of state is applied to describe the absorption of CO2 in aqueous solutions of single and blended amines at conditions of relevance for post-combustion CO2 capture. A scheme of implicit reactions is used to describe the formation of carbamate and/or bicarbonate products resulting from the chemical reactions between CO2 and five amines of practical industrial interest. This procedure eliminates the need to specify the detailed equilibrium reactions and significantly reduces the number of parameters required to represent the absorption process. A maximum of two adjustable model parameters (one of which with a linear temperature dependence), optimised for a fixed amine concentration, suffices to represent the absorption of CO2 in aqueous solutions of single amines over a broad range of temperatures (298–413 K) and partial pressures of CO2 (0.1–1000 kPa). The extrapolation capabilities of the model are tested by predicting the absorption of CO2 in aqueous solutions of single amines for different amines concentrations (∼8.5–35 wt%), with modelling results showing good quantitative agreement with solubility, speciation and enthalpy of absorption data available in literature. Furthermore, without introducing any new model parameter, the absorption of CO2 in various amine blends is satisfactorily predicted by considering competing interactions for the reactive sites in the model of CO2. The developed models are then used to assess the CO2 capture performance of selected amine systems in terms of two key process parameters: solvent cyclic capacity and regeneration energy. Results for systems with the same total amine mass concentration show that the highest molar cyclic capacities are obtained for 30 wt% piperazine (0.45 mol CO 2 .mol Amine - 1 ), whereas the greatest energy savings for solvent regeneration are estimated for 30 wt% methyldiethanolamine (2.3 GJ .tCO 2 - 1 ). Moreover, two piperazine–promoted blends showed the potential for reducing up to ∼26% the energy consumption for solvent regeneration and separating up to ∼41% more CO2 in a molar basis when compared to the benchmark 30 wt% monoethanolamine. Altogether, these results demonstrate the feasibility of the developed approach as a reliable platform for the screening of amine solvents as function of key process parameters, and as a valuable tool for process modelling.

This work deals with stochastic calculations for the dynamics of granular flows in rotating cylindrical drums, using the discrete element method (DEM). The drum is 100 mm in diameter and 35% filled with 3-millimetrediameter spheres rotating at various speeds. The deterministic model is extensively validated through reported studies in terms of the dynamic repose angle and spatial velocity fields. The stochastic simulation study focuses on the uncertainties related to the physical particle characteristics that simultaneously influence the granular flow interactions, such as friction coefficients, restitution coefficients, Young's modulus, Poisson's ratios and others input parameters. The uncertainty propagation from the model input parameters to the output stochastic solution is quantified using non-intrusive chaos expansion. Throughout this work, the study focuses on the behaviour of particles within a rotating drum, as many industries use this type of configuration for their processes. This method allows for the determination of stochastic solutions from a set of deterministic simulations. The simulation variables (such as particle velocities and dynamic angles of repose) are characterized in terms of the stochastic mean, probability density function and error bar. For the uncertainty propagation, the random friction coefficient is the most dominant input variable for the granular flow dynamics in a horizontal drum.

The development of new alkanolamines/amines is a topic which has attracted a great deal research interest, particularly as absorbents for the removal of acid gases from industrial sources and CO2 capture applications. One of the major challenges when evaluating the techno-economic performance of selected new single amines or blends is the lack of experimental data on the thermophysical properties required for a reliable process design and simulation. In this contribution, a robust theoretical framework for the description of key thermophysical properties of aqueous solutions of single and mixed alkanolamines/amines at relevant gas separation process conditions is proposed. The approach is based on the coupling of the Free-Volume Theory and the Density Gradient Theory with a molecular-based equation of state (soft-SAFT) for the integrated modelling of phase behaviour, enthalpies, densities, viscosities and interfacial tensions. The alkanolamines and amines investigated differ in their family and structure, and included primary (monoethanolamine), secondary (diethanolamine), tertiary (methyldiethanolamine), sterically hindered (2-amino-2-methyl-1-propanol) and cyclic amines (piperazine). The study was performed in a systematic manner, starting from the development of the models for the pure amines, the description of their thermophysical properties, and the properties of the aqueous mixtures. Compared to other models described in literature, the present modelling approach preserves the effects due the chemical structure and key intermolecular interactions of the examined alkanolamines/amines through a set of molecular parameters obtained from pure substance data, whenever available, or transferred from substances of different chemical families. This enabled the development of a consistent modelling framework which can provide reliable thermodynamic property predictions of both single and blended amine solutions over a broad range of temperatures (298–373 K) and compositions (0–50 wt% amine). The proposed approach is well-suited for implementation and extension to other alkanolamines and amines, making it a valuable tool for having reliable process simulations as well as for the screening and discovery of new amine systems, which will be required for the deployment of more economical acid gas removal processes.

In this study the interfacial tension (IFT) between CO2 and brines, in the context of geological storage of CO2, was investigated. Investigations covered both experimental and theoretical aspects of this property over a broad range of conditions, including those found in subsurface formations. Measurements for CO2 + NaCl(aq) systems, of salt molalities 0.98 and 1.98 mol.kg-1, were performed for temperatures and pressures up to 423 K and 69.51 MPa, respectively. Results clearly showed an increase from CO2 + H2O IFT upon the addition of the salt, helping to resolve some discrepancies observed in literature data. Furthermore, a predictive method, based on the Density Gradient Theory, was extended to CO2 + brine systems, with modelled IFT values yielding a good agreement with experiments from this work and literature for brines of single and mixed salts, including NaCl, KCl and CaCl2, and ionic strength up to 2.7 mol.kg−1.

Thermal analysis and management studies are commonly conducted from early design stages of new products by numerical means. However, the application of three-dimensional tools for evaluating the thermal performance of multi-component systems, exhibiting high geometrical and phenomenological complexities may become unpractical in view of the long computational times. Therefore, a methodology for thermal analysis of complex thermal systems is developed to improve the overall numerical convergence rate. The methodology is based on an iterative two-way coupling procedure between two sets of simulations: simulation set where critical components are individual and fully simulated (component-level simulations); and simulation framework where the overall system is considered with hollow components (system-level simulation). A communication strategy between both simulation sets is established. The methodology can be readily applied for performing thermal management studies. A verification procedure for the suggested methodology is firstly carried out. Afterwards, the methodology is applied to investigate the thermal performance at the system-level of a fuel cell based μ - CHP unit, namely regarding the feasibility of components integration. The methodology application allowed the identification of critical hot-spots (with temperatures up to about 400 ° C ) on the surface of the unit internal components, mainly due to an inadequate insulation thickness and shape.

There are several ways to change the final properties of composite materials, but the most common one is by adding different types of modifier fillers to the polymeric matrix. Over the last years, nano fillers have brought some interesting properties to composites. Until now, only few works were published concerning the effective impacts of resin binder modification with nano oxides, on mechanical properties of polymer mortars (PM). In this study, unsaturated polyester based PMs with enhanced mechanical performance are developed through polymer modification with nano-sized Al2O3 and ZrO2 particles. Samples without and with nanoparticles (2.5 resin wt.%) were produced, and their mechanical/physical properties assessed by flexural, compressive and Shore D hardness tests. The PM modified with nano zirconia showed better mechanical performance compared to the unmodified PM; more thorough studies are nevertheless required in order to improve mix design formulations towards further enhancement of mechanical behaviour.

Calculations of continuous glass melting in a single-mode 2.45 GHz microwave oven are reported. The aim of this work is to optimize the microwave heating of the glass raw material to have a controlled and highly efficient oven. The two-way coupling process between electromagnetic and thermal fields is solved using COMSOL software in a 3D transient simulation that includes phase change and surface-to-surface thermal radiation. A methodology was developed and coded to automatically control the microwave energy supply and to maximize the material's microwave absorption during the 3D transient simulation. The developed methodology to achieve high Key Performance Indicators (KPI) was applied to the continuous melting of a glass raw material powder, the results show promising energy consumption reduction and improved task efficiency.

This study deals with the topic of synthesis gas (syngas) production from preheated, rich methane/air mixtures. The examined process is based on non-catalytic partial oxidation within a small-scale porous media based reformer, intended for application in Solid Oxide Fuel Cell (SOFC) based systems. For this purpose, process characteristics like temperature profiles within the porous material and exhaust syngas compositions were experimentally and numerically investigated under conditions that can be encountered in such systems. The soot content of the generated syngas was also measured using the technique of Scanning Mobility Particle Sizing. An important feature of the reformer, which was demonstrated during the experiments for a wide range of thermal loads (380–1895 kW/m2) and equivalence ratios (1.9–2.6), is the ability to operate based on stationary flames. This is achieved using a two-section design. The sections show a conical and a cylindrical geometry, whereas the same porous medium is installed in both of them. For this study, the solid matrix was created as packed bed of Al2O3-Raschig rings (62% open porosity). The process was simulated with a quasi-1D numerical model, which uses a volume-averaged approach. The model solves both the gas- and solid-phase energy balances explicitly and accounts for the radiative heat transport in the solid-phase. Peak temperatures measured within the porous zone provide evidence of superadiabatic combustion, which is also confirmed by the numerically predicted temperature profiles with the model. Syngas compositions reveal a maximum reforming efficiency of 65% based on H2 and CO, while the soot limit of the process was found to lie at φ = 2.2, regardless of thermal load and preheat temperature of the fresh mixture.

Combustion within porous inert media is an effective way in order to obtain high radiant outputs for a large range of power densities, while simultaneously reducing pollutant emissions. Due to the complex interactions between the different heat transfer modes involved, the parameters that influence the heat transfer process hold much potential in terms of optimization of the porous radiant burner performance. In this respect, advanced 3D-printing techniques allow for the manufacturing of non-conventional porous media configurations, with possibility for tailoring geometric and radiative properties to a specific design demand. A progressive multi-dimensional parametric investigation is conducted with the aim of characterizing the range of different geometric, radiative and operating parameters that yields optimal porous radiant burner operation, with focus on the radiant efficiency and peak solid temperature. A one-dimensional porous media combustion model is employed as a black-box, including coupled gas and solid energy equations, multi-step chemical kinetics and radiative heat transfer. The model input parameters are made independent as much as possible, leaving aside existing property correlations. An application code is developed in order to explore the parametric domain defined by the investigated parameters. It performs the autonomous management of the model simulations, assigning adequate starting estimates in order to facilitate the successful and efficient convergence of parametric simulations. It is found that, among the 8 input parameters investigated, the emissivity, excess air ratio, extinction coefficient and scattering albedo are most determinant parameters for achieving the best porous radiant burner performance, improving the radiant efficiency in more than 50% when compared to the typical values from literature. Moreover, the results from the multi-dimensional parametric study show that an individual sensitivity analysis is not sufficient for getting the best improvement, since the non-linear cross-influence of several parameter is relevant.

The deployment of more efficient and economical extraction methods and processing facilities of oil and gas requires the accurate knowledge of the interfacial tension (IFT) of fluid phases in contact. In this work, the capillary constant a of binary mixtures containing n-decane and common gases such as carbon dioxide, methane and nitrogen was measured. Experimental measurements were carried at four temperatures (313, 343, 393 and 442 K) and pressures up to 69 MPa, or near the complete vaporisation of the organic phase into the gas-rich phase. To determine accurate IFT values, the capillary constants were combined with saturated phase density data measured with an Anton Paar densitometer and correlated with a model based on the Peng–Robinson 1978 equation of state (PR78 EoS). Correlated density showed an overall percentage absolute deviation (%AAD) to measured data of (0.2 to 0.5)% for the liquid phase and (1.5 to 2.5)% for the vapour phase of the studied systems and P–T conditions. The predictive capability of models to accurately describe both the temperature and pressure dependence of the saturated phase density and IFT of 16 (gas + n-alkane) binary mixtures was assessed in this work by comparison with data gathered from the literature and measured in this work. The IFT models considered include the Parachor, the Linear Gradient Theory (LGT) and the Density Gradient Theory (DGT) approaches combined with the Volume-Translated Predictive Peng–Robinson 1978 EoS (VT-PPR78 EoS). With no adjustable parameters, the VT-PPR78 EoS allowed a good description of both solubility and volumetric properties of the mixtures measured in this work, with deviations to measured density data only slightly higher than those of correlated data. The best IFT predictions were obtained with the DGT method with an overall %AAD between (4.9 and 8.3)% for all systems considered and IFT data no lower than 1.5 mN · m−1. Furthermore, the impact of the relative adsorption of gas molecules in the interfacial region on the IFT was further investigated with the DGT.

It is well established that the presence of salt in the aqueous phase raises the interfacial tension (IFT) of gas–water systems when compared to the case of pure water under the same pressure and temperature conditions. However, experimental data for gas–brine systems is still scarce, in particular at high pressure and high temperature (HPHT) conditions. In this communication, IFT data for methane with distilled water were experimentally determined using the pendant drop and bubble rise methods for temperatures ranging from (311–473) K and pressures up to 92 MPa and the results compared against literature data. Moreover, for the first time, the effect of NaCl on the IFT of the methane–water system was investigated in solutions with a maximum salinity of 10 wt% at HPHT conditions. The Cubic-Plus-Association equation of state (CPA EoS) along with the Debye–Huckel activity model was used to describe the effect of salt in the phase behaviour of the methane–water system and bulk properties used to compute the IFT of the studied systems with the Density Gradient Theory (DGT). The modelling results showed that by using only bulk phase properties and one temperature independent binary interaction parameter adjusted to the methane–water system, the DGT was able to predict the impact of NaCl on the IFT with remarkably low deviations from measured values. Furthermore, the impact of the fluids microstructure and the distribution of molecules across the interface on the IFT were evaluated with the DGT.

New experimental data for the surface tension of 6 liquid 1H,1H-perfluoroalcohols (CF3(CF2)nCH2OH, n = 0, 1, 2, 3, 4, 5) was measured as a function of temperature between 260 K and 350 K. The new data fills an important gap in the available literature. The results are interpreted comparing with data from the literature for the equivalent hydrogenated alcohols. Atomistic molecular dynamics simulations were performed providing detailed structural information on the interfaces at the molecular level. The soft-SAFT-DGT equation is used to model the experimental results. In addition to surface tensions, a full characterization of the phase equilibria and bulk properties is performed with soft-SAFT, including second order derivative properties such as vaporization enthalpy, isothermal compressibility and thermal expansion coefficient. Excellent agreement was found between the theoretical predictions and the experimental results.

Asphaltenes analysis still remains a challenge due to their unknown molecular structure and self-associative behavior. FT-ICR MS analyses using five different ionization methods, ESI, APCI, APPI, LDI and MALDI, in both positive and negative mode were performed. A characteristic and typical behavior was observed for the experiments using LDI(±) and MALDI(±)FT-ICR analyses: a broadband mass spectrum ranging from m/z 500 to 3000 was observed with a 24 Da interval. This phenomenon was attributed to fullerene cluster formation. The most abundant allotropic form of fullerene, C 60 , was observed at m/ z 719.99914. These species were not observed in APCI(+)/APPI(+) analyses. This last analysis of asphaltene samples doped with the C 60 solution promptly reveals the typical fullerene ions. LDI(+) analyses of pure C 60 showed condensation products. These results indicate a clusterization of asphaltenes in the LDI/MALDI plume, which showed a highly dependency on the laser power density. The dispersion of LDI results on carbonaceus samples in the literature is associated with the lack of control of these parameters. However, to access the sample composition, APPI and APCI should be more suitable.

Microwave heating processes are highly sensitive to variability in the operating frequency and usually there are high uncertainties associated with measurements of the material's imaginary permittivity. Therefore, the harmonic Maxwell's equations and time dependent heat equation are considered for the simulation of high temperature ceramic microwave heating with uncertain operating frequency and dielectric constants. To analyze the uncertainty of the system, the Non-Intrusive Spectral Projection Method (NISP) is used based on the Polynomial Chaos expansion. The conclusions of this work indicate that 13 Gauss collocation points and a polynomial degree of 11 must be used with the NISP in order to obtain accurate results. Furthermore it also adds that uncertainty in frequency leads to high values of variability in the stochastic solution. The uncertainty in the material's imaginary part of permittivity has only a significant impact for high temperatures of the material. Temperature probability density functions, error bars and standard deviations characterize the material heating up to high temperatures.

The impact of the catalyst internal structure on the conversion rates of CO oxidation is investigated using a 3D multi-scale bottom-up approach for transport and reaction modeling in isothermal porous catalyst layers. The multi-scale methodology is employed to evaluate effective diffusion coefficients that are further compared with the values predicted with the random pore model. Multi-scale reaction–diffusion simulations are performed and compared with the results of the 1D pseudo-homogeneous, continuum approach. CO oxidation described by a single-step reaction mechanism is used to demonstrate the methodology, although it is extensible to any set of catalytic reactions. Digital reconstruction techniques are employed to generate porous media with specific structural properties representative of two different length scales (nano and micro). On the nano-scale level, diffusion simulations along the mesopore network are carried out to evaluate effective diffusivity values that are further exported to the micro-scale level where diffusion and reaction–diffusion simulations are considered. Several washcoat layers were reconstructed varying only the grain size distribution and the partial overlapping between micro-particles. Multi-scale diffusion simulations showed that the random pore model is only suitable for specific porous structures. Furthermore, the comparison between the results of the multi-scale and 1D reaction–diffusion models also showed that by providing an accurate estimation of the effective diffusivity data for the 1D model, namely through multi-scale diffusion simulations, instead of the random pore model results, a significant agreement is verified between both models.

A clean, efficient and facile one-pot protocol was developed for the synthesis of a series of new aminonaphthoquinones derived from 2-hydroxy-1,4-naphthoquinone (lawsone) by three-component Mannich reaction using catalytic amount of p-TsOH in CH3CN, at room temperature. At the present work, we improved the yield and significantly reduced the reaction time for several Mannich reactions with different amine and aromatic aldehydes using a non-expensive, mild catalyst and suitable solvent.

Although the term “naphthenic acids” was originally used to describe acids that contain naphthenic rings, today this term is used in a more general sense and refers to all components in the acid extractable fraction. In crude oil, naphthenic acids exist as a complex mixture of compounds with broad polydispersity with respect to both molecular weight and structure. There has been increasing interest in the naphthenic acids in crude oil because of the corrosion problems that cause during oil refining. Herein, two powerful analytical tools, negative-ion electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry, ESI(-)FT-ICR MS and atomic force microscopy (AFM), were combined to monitor the thermal degradation of naphthenic acids and their corrosion effects on AISI 1020 steel, respectively. Two different acidic crude oils (TAN = 2.38 and 4.79 mg KOH g −1 , and total sulfur = 0.7993 and 1.0220 wt%) have been submitted to thermal treatment at 280, 300 and 350 °C during 2, 4 and 6 h, and characterized by ESI(-)-FT-ICR MS, total acid number (TAN), and total sulfur. The AISI 1020 steel was analyzed by scanning electron microscopy (SEM) and AFM. Generally, heating the crude oil at 350 °C in a period of 6 h, it was observed that a high efficiency (≅80%) and selectivity of thermal decarboxylation process was monitored by decay of TAN (4.79 → 0.44 mg KOH g −1 ). ESI(-)-FT-ICR MS results showed that naphthenic acid species remained after the heating have DBE ranging 1–12 and carbon number from C 15 to C 45 . AFM topographic profile evidenced that the naphthenic acid corrosion of the crude oil with TAN of 4.73 mg KOH g −1 on AISI 1020 steel was profoundly altered and a marked reduction in peak to peak height values (obtained by subtracting the value of the lowest peak by the highest peak in the topographic area examined). Optical images and microphotographs confirmed the presence of irregularities, characterizing the corrosion mechanism as pitting type. The naphthenic corrosion was also evidenced in samples with low TAN value (0.44 mg KOH g −1 ).

The role of the reactor geometry for catalytic partial oxidation of methane is numerically investigated to improve catalyst thermal stability and at the same time to achieve high fuel conversion and reforming efficiency. The performance of cylindrical-shaped foam monolith reactors is compared with that of conical-shaped foam monolith reactors. A quasi-1D heterogeneous mathematical model was developed to account for a variable reactor cross-sectional area and for a variety of chemical and transport steps. Radiative heat transfer within the cellular structure was properly accounted for with the zone method. The results suggest that converging conical-shaped reactors allow a significant decrease of the maximum surface temperatures and high reforming performance.

Methane Thermal Partial Oxidation (TPOX) within a small scale Inert Porous Media (IPM) based reactor was investigated numerically in order to explore the operating conditions and possible procedures for maximizing the reforming efficiency and minimizing the soot formation. A quasi-1D model of the TPOX reactor was validated and further used to study the process. The model considers detailed chemistry and solves the energy balances for both gas and solid phases, including radiative heat transfer in the solid phase. The parametric results of the reactor operation show that the optimal air–fuel ratio is a compromise between soot formation and reforming efficiency. Moreover, a high preheating temperature of the reactants is found to be always beneficial for the process, and the effect of power input is negligible for the reforming efficiency. The numerical investigations also suggest that shorting the IPM length, as well as mixing small amounts of water vapor with the reactants, appear to be effective procedures for improving the operation performance of the TPOX reactor.

Asphaltenes can be considered like the ‘bad guys‘ when heavy petroleum are transported or upgraded. These compounds are not classified by the their chemical structures but by the solubility class, that is defined as solubles in aromatic solvents, such as toluene, and insolubles in n -alkanes, such as n -heptane. Here, we analyze three crude oil samples (classified as extra-heavy, heavy and asphaltic having API degree of 17.3, 22.0 and 13.5, respectively) and their asphaltenes by atmospheric pressure photoionization (APPI) coupled to Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) in positive and negative ionization modes, APPI(±)-FT-ICR MS. We apply the DBE (double bond equivalent) versus carbon number (CN) plots as the aim of to predict the aromaticity of crude oil and their asphaltenes. Additionally, average molecular weight, M w , heteroatomic-containing compounds profile and van Krevelen diagrams were constructed to visualize and interpret the MS data. MS data were compared and discussed with aromaticity parameters obtained from elemental analyses and 1 H NMR measurements. For three crude oils analyzed with different magnitude of the viscosities (III > II > I), the amount of the asphaltene extracted follower the behavior analogous (7.63 ± 0.65 wt%; 2.23 ± 0.25 wt%; and 0.41 ± 0.01 wt%, respectively). The aromatic hydrogen content ( H ar , in molar%) was determined from 1 H NMR, where the heavier crude oil and its asphaltene ( H ar = 4.90 and 27.3 M%, respectively) were slightly more aromatic than other. An inverse correlation was observed between H ar values and the N and O concentrations determined from elemental analyses. For APPI(±)FT-ICR MS data, the values of M w observed for asphaltenes ( m / z 200–650) were significantly distinct, being correlated with the physico-chemical characteristics of their parent crude oil. Using the concept of planar limited, the line generated by connecting maximum DBE values at given CN in the DBE versus carbon number plots, it was possible to extract the aromaticity degree from APPI FT-ICR MS data. The slopes of these lines determined by DBE/carbon number ratio were calculated by linear regression for protonated hydrocarbons (HC[H]) and basic nitrogen (N[H]) compounds classes. We observed an increase in slopes in function of an increasing of the H ar values.

In this work, electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI(±)-FT-ICR MS) was applied in the chemical characterization of polar compounds. These compounds were identified as the oxygen-containing compound classes (naphthenic acids, O2 class, and phenols, O1 class), the sulfur-containing compound classes (mainly sulfides, S1 class), and the basic and non-basic nitrogen-containing compound classes (carbazoles and pyridines, N class). For access the sulfur-containing compounds were employed the methylation reactions. As the increasing of distillation cut temperature, the amount of O2 compounds increased (from 9 for cut 2 to 66 for cut 12), and the average molecular weight distribution, Mw, shifted to higher m/z values (Mw = 169 → 321 Da). These results were consistent with the increase of TAN with the boiling point. Plots of the DBE versus the carbon number for the O2 class of heavy distillation cuts (cuts 4–12) suggested a maximum abundance of the carbon numbers located at C12–C18 with a constant DBE of 3. For the nitrogen-containing compounds, 100 compounds were detected with m/z ranging from 160 to 414. Similar to O2 class, the amount of nitrogen species increased, and the Mw shifted for high values in function of distillation cut temperature: 6 species and Mw = 206 Da for cut 3; and 64 species and Mw = 340 Da for cut 12. The structures and the connectivity of naphthenic acids, phenols and pyridines were confirmed using ESI(±)-MS/MS. The most abundant sulfur compounds in heavy distillation cuts presented a carbon number of C23 (for cut 11) and C25 (for cut 12) with constant DBE of 3. Results of ESI(±)-FT-ICR MS contributed to the understanding of the chemical composition of Brazilian crude oil and the establishment of a correlation with the corrosion process.

Nanocomposites of ultra-high molecular weight polyethylene reinforced with multiwalled carbon nanotubes (UHMWPE/MWCNT) have been prepared with different volume fractions of MWCNTs: 0.2, 0.4, 0.6, 0.8 and 1.0%. DMTA experiments were carried out using a TA Instruments Q800 equipment and the samples were cut from the compressed sheets of polymer and composites. The experiments were conducted on each sample at 12 different frequencies varying from 0.1 Hz to 100 Hz over the temperature range of 22-82 degrees C at an interval of 5 degrees C where the reference temperature was kept at 37 degrees C. It was verified that both horizontal and vertical shifts are necessary to superimpose the dynamic modulus/frequency curves of all cases. The MWCNT did not seem to change the viscoelastic nature of the UHMWPE, i.e. incorporation of up to I wt.% of MWCNTs has negligible influence on the viscoelastic behaviour of the UHMWPE. Hence the same analytical model is applicable for the viscoelastic description of the nanocomposites.

The kinetic behaviours of two commercial epoxy resin systems subjected to manufacturer’s recommended cure cycles (MRCC) were studied in detail. The two systems were characterized through differential scanning calorimetry (DSC) using both isothermal and dynamic test conditions. The kinetic parameters were determined and two original kinetic models were established for these resin systems subjected to the “real” processing conditions. In this paper the experimental procedure is described, together with its results and the original kinetic models developed.

The lean premixed combustion of hydrogen and carbon monoxide (H2/CO) mixtures within a porous inert media model-burner was investigated for ranges of H2/CO volumetric ratios from 2 to 4, inert volumetric concentrations in the fuel stream from 85% to 90%, thermal loads of 400 kW/m2 (2 kW) and 1000 kW/m2 (5 kW), constant reactants temperature of 673 K and an equivalence ratio of ϕ = 0.5. Experimental measurements and numerical predictions of temperature profiles and temperature gradients along the axial center-line of the combustion zone are presented and the thermal flame thickness is estimated and analyzed for the effect of thermal load, inert components in the fuel stream and H2/CO ratios. The adopted numerical model uses a volume-averaged approach and solves both the gas- and solid-phase energy balances explicitly and accounts for the radiative heat transport in the solid-phase. The thermal flame thickness results are compared with the respective laminar free flame values and differences between the flame thickness of free flames and flames inside a porous inert media are discussed.

Propagation of uncertainty through the physical model has been investigated in the present paper by solving two specific simple stochastic problems using the Non-Intrusive Spectral Projection method. The uncertain parameters are described by either a Gaussian or a LogNormal probability distribution function. For each of the problems, the stochastic and the deterministic mean solutions have been compared and the respective confidence intervals have been obtained. For the deterministic problems, the confidence intervals have been estimated using both one-dimensional and multi-dimensional bound methods. From the results it has been observed that the differences between the stochastic and the deterministic mean solutions are apparent only when large uncertainties are introduced in the random variables. For both the specific problems, considered in the present study, the confidence intervals for the stochastic problems have been exactly predicted by the deterministic limits when uncertainty is introduced only in one of the parameters. For more than one uncertain parameters, the multi-dimensional bound method produces better agreement with the stochastic confidence intervals than the one-dimensional bound method. The findings are expected to be applicable to problems in heat and mass transfer with similar characteristics or input–output relations.

This work presents the use of carbon nanotube (CNT) skeletons and the resin infusion process as a path towards the production of polymer composites with high and well dispersed nanotube content. A general purpose low viscosity epoxy resin was used as matrix in the reported process assessment. Thin CNT papers, called skeletons, were initially produced to obtain CNT networks. The impregnation was made by infiltrating the non-diluted resin through the carbon nanotube structure. The results show the proposed processing approach as one capable of producing well dispersed nanocomposites with high CNT loading (more than 15 wt% CNT by composite weight), which are important for developing high performance structures based on carbon nanotubes with good thermal and electrical conductivity. The absolute mechanical performance was lower than expected, and discussed in light of manufacturing problems detected by microscopy observations under scanning electron microscopy (SEM).

This paper focuses on the numerical simulations of methane thermal partial oxidation reforming process within inert porous media and their comparison with experiments. In order to produce hydrogen rich mixtures and for the sake of reaction stability, the reformer consists on a diffuser filled with porous media. The validity of using a quasi-1D approach to model this system is explored based on 3D simulations of the isothermal fluid flow through the porous solid structure. Several fluid flow cases were taken into account as well as two different porous materials, Al2O3 fiber lamellae and SiSiC foam. The detailed fluid flow information obtained from the 3D study was used to provide the realistic cross-sectional area variation of the quasi-1D model. The quasi-1D 12-steps reduced chemistry model predictions are in very satisfactory agreement with the temperature and concentration fields measured within the diffuser porous reformer.

This article presents a statistical approach called hypothesis testing. This is based upon information collected from a random sample following which results are generalised for the entire population. Some general concepts and terminology of the methodology are briefly described including statistical hypotheses, types of errors, one- or two-tailed tests and an example of an application is given. Hypothesis testing is a fundamental process in making a decision about populations of interest in research.

The preparation of new layered double hydroxides/unsaturated polyester (LDH/UP) nanocomposites was performed and the effect of LDH on the resin properties was studied. Two different organo-LDHs have been prepared, adipate-LDH (A-LDH) and 2-methyl-2-propene-1-sulfonate-LDH (S-LDH); in order to evaluate the influence of these nanofillers, samples with two different concentrations were dispersed in the matrix. The physical, thermal, mechanical and fire reaction properties of nanocomposites were studied. Intercalated layered structures were observed for the different organo-LDH loadings (1 and 5 wt%). Mechanical properties studied under flexural tests show that incorporation of organo-LDH in the resin reduces the flexural strength of polyester resin while the flexural modulus is unchanged for the S-LDH/UP composites and increased with 1 wt% of A-LDH. Adding 1 wt% of A-LDH to the resin produces an important reduction on the flexural strength, but an increase of the flexural modulus. The study of fire reaction properties, using cone calorimeter, suggested a significant reduction in the UP flammability, by 46 and 32%, by incorporating 1 wt% of A-LDH and 5 wt% S-LDH, respectively. Mass loss curves show enhanced char formation with the different loads tested while the amount of evolved smoke remains quite unchanged.

A natural Brazilian montmorillonite clay was submitted to organophilization treatments to evaluate the effect of these treatments on the flame retardancy potential of polymer composites containing an intumescent ammonium polyphosphate and pentaerythritol formulation. An ethylene–butyl acrylate copolymer was used as the polymer matrix. Natural or organophilic clays were added both to the pure polymer and to the polymer containing the intumescent mixture. The influence of these mineral fillers, and of their organophilization treatments, on flame retardancy was investigated by thermogravimetric analysis (TGA), limiting oxygen index (LOI), UL-94 rating standard, heating microscopy, rheological measurements and cone calorimetry. The results show that these inorganic additives have a synergistic effect on composites containing the intumescent formulation.

We report the identification of two distinct homologues of the 70-kDa mitochondrial heat shock protein (mtHSP70) from Leishmania chagasi/Leishmania infantum (Lc2.1 and Lc2.2). In Leishmania species, multiple genes encoding Lc2.2 are present whilst single genes encode Lc2.1. Strikingly, genes encoding Lc2.1-like proteins are absent from Trypanosoma species. Lc2.2 is characterized by a poly-glutamine rich C-terminus, absent from Lc2.1 or mtHSP70 homologues outside the trypanosomatids. Lc2.1 displays unique substitutions within its peptide-binding domain which modify amino acids strictly conserved in cytoplasmic and mitochondrial HSP70 proteins alike. Affinity purified antibodies recognize mainly a single protein in extracts from promastigotes/epimastigotes of various Leishmania/Trypanosoma species. Upon differentiation of Leishmania amazonensis into amastigotes a second protein (presumably Lc2.1) is induced and becomes the predominant mtHSP70 homologue expressed. Subcellular localization of these proteins was investigated and ratified a distribution throughout the mitochondrial matrix. Our results imply novel mtHSP70 functions which evolved within the genus Leishmania.

We report a study about the structural properties of polycrystalline samples of nominal composition Gd 5 Ge 2 (Si 1− x Sn x ) 2 ( x =0.23, 0.40) that closely influence their physical behavior particularly related to electric resistivity and magnetocaloric (MCE) effect. The samples were characterized by X-ray diffraction (XRD) using the Rietveld refinement method, metallographic analyses, 119 Sn Mossbauer spectroscopy, DC magnetization and electrical transport measurements. It was identified a Gd 5 Si 2 Ge 2 -monoclinic phase for x =0.23 and a Sm 5 Sn 4 -orthorhombic phase (type II) for x =0.40, both with two non-equivalent crystallographic sites for the Sn ions. We were able to infer on the role of tin on the magnetic and transport properties in these compounds.

Medium-density fiberboard (MDF) is a wood-based panel manufactured from wood fibers with a synthetic adhesive through the conduction of heat from the hot platens. One alternative is the use of high-frequency (HF) heating, which has the advantage of reducing the press cycle, the platens temperature and the post-curing time, with constancy of resin formulation. For this approach, an electromagnetic (EM) heating model was developed and coupled with a three-dimensional model for heat and mass transfer and resin polymerization already existent. A solution of the Maxwell equations is used to determine the spatial distribution of the electric field inside the material and the absorbed power. MDF mat was assumed as a porous and homogeneous material at macroscopic level and a dielectric mixture at microscopic level (volume of control). The mat dielectric properties (wood fibers/particles and UF resin) were estimated using a “rule of mixture” and depend on local temperature and moisture content during the heating process. This dynamic model was used to predict the evolution of the local variables related to heat and mass transfer (temperature and moisture content), as well as the variable connected to the EM behavior (dielectric properties of the mat). The model performance was analyzed using the experimental results of HF ( 13.56 MHz ) MDF heating. It was concluded that the model could suitably predict the evolution of the internal mat temperature during heating.

AUTOSOMAL dominant amyloidoses characterized so far are most commonly associated with transthyretin (TTR), a plasma protein synthesized by the liver. The single gene for TTR is located on human chromosome 18; more than 70 TTR mutations have been documented. The most common type of hereditary amyloidosis is familial amyloid polyneuropathy type I (FAP, Portuguese type), a neuropathic form associated with a substitution of methionine for valine at position 30 of the TTR gene, TTR Val30Met. The largest number of patients and families with this mutation has been identified in Portugal, but now it has been recognized worldwide. FAP in Portugal usually begins in the third or fourth decade of life with death occuring about 11 years later. The clinical disease usually starts as a sensory neuropathy in the lower extremities, but autonomic and gastrointestinal features may occur early. Motor neuropathy usually manifests itself later with cardiac conduction disturbances frequently leading to the need for artificial pacing. Vitreous deposits of amyloid have been reported, most particularly in Swedish families. Cachexia has been described as a significant factor in mortality. Orthotopic liver transplantation (OLT) is widely recommended for patients affected by FAP; it is recognized as the only specific treatment for this disease. Virtually all TTR is produced by the liver, and, therefore, OLT halts the supply of variant amyloidogenic TTR (ATTR). Amyloid proteins have different organ specificity, leading to variations in clinical features. Classically, nephropathic and nonneuropathic autosomal dominant amyloidoses are associated with apolipoprotein A-I and A-II, fibrinogen A -chain, and lysozyme. Renal amyloidosis also has been described in FAP. In Portugal, approximately one third of FAP patients have clinical renal features with varying degrees of proteinuria and renal failure. The progression to end-stage renal disease (ESRD) occurs in 10% of Portuguese patients, more than 10 years after the onset of symptoms (Lobato et al, unpublished data). Although dialysis may prolong life, it does not prevent the progression of systemic amyloid involvement; death occurred, on average, at 22 months after renal replacement therapy. The cause was infection in one half of the patients (Lobato et al, unpublished data). The first successful renal transplantation in a patient with renal amyloidosis was reported in 1968, but until now this treatment has been associated with poor graft and patient survival. Most published series concerning renal transplantation in amyloidosis deal with familial Mediterranean fever or other forms of reactive amyloidosis (AA type). The results of kidney transplantation in ATTR have not been described. In patients with FAP undergoing dialysis, the potential advantages of simultaneous liver-kidney transplantation instead of isolated kidney transplantation are to avoid the progression of systemic manifestations and the recurrence of renal amyloidosis. The obstacles to renal transplantation

Venom immunotherapy (VIT) is an effective treatment for most subjects who are allergic to hymenoptera venom. We have studied 22 patients (16 honey bee venom allergic and 6 vespula sp. venom allergic) subjected to immunotherapy with aqueous extract of pure venom from Allbay, Dome-Hollister-Stier. In one group of 12 patients, VIT was performed according to a rush protocol and we measured specific IgE and IgG4 during a 4-year follow-up period. We observed a decrease in specific IgE and an increase in specific IgG4 in all patients. In order to determine the safety of ultra-rush protocols (3.5 h) we have recently selected one other group of 10 patients in whom we measured tryptase release during the 24 h (at 2, 3, 4, 6, 8, 10, 12 and 24 h) after the beginning of the ultra-rush schedule. We observed no increase in adverse reactions during the induction or maintenance phase relative to rush protocols. Regarding tryptase levels, we observed no significant differences between basal and the several measurements performed during the ultra-rush VIT schedule. These results suggest that an increase in specific IgG4 is correlated with the protective effect of immunotherapy and that ultra-rush VIT is not associated with significant mast cell activation. Ultra-rush protocols are clinically safe, with a rate of systemic reactions similar to rush protocols and with less local reactions. There is no evidence of ultra-rush VIT induced mast-cell degranulation, and serum tryptase levels have not shown significant variations during ultra-rush VIT.

Specific immunotherapy (SIT) is effective in the treatment of allergic rhinitis but its mechanisms of action are still not completely understood, particularly in regard to eosinophil activation mechanisms. The purpose of this research was to study if the inhibition of eosinophil activation, demonstrated through the reduction of eosinophil cationic protein [ECP] release, is involved in the therapeutic actions of specific immunotherapy. We analyzed ECP concentrations in nasal lavage fluid of 21 patients with allergic rhinitis, before and after specific nasal provocation. These results were compared to controls, treated without specific immunotherapy. ECP concentrations in nasal lavage fluid were significantly reduced after two years of specific injectable immunotherapy. These reductions were demonstrated both in pre-provocation [basal] values and after specific nasal provocation. Specific immunotherapy can reduce ECP in nasal lavage fluid of in house dust mite allergic rhinitis patients, both before and after allergen nasal challenge, with significant changes in the kinetic of ECP release, a fact which suggests that specific immunotherapy can influence eosinophil activation or its releasability.

Chloride channels play an important role in the physiology and pathophysiology of epithelia, but their pharmacology is still poorly developed. We have chemically synthesized a series of substituted benzo[c]quinolizinium (MPB) compounds. Among them, 6-hydroxy-7-chlorobenzo[c]quinolizinium (MPB-27) and 6-hydroxy-10-chlorobenzo[c]quinolizinium (MPB-07), which we show to be potent and selective activators of the cystic fibrosis transmembrane conductance regulator (CFTR) chloride channel. We examined the effect of MPB compounds on the activity of CFTR channels in a variety of established epithelial and nonepithelial cell systems. Using the iodide efflux technique, we show that MPB compounds activate CFTR chloride channels in Chinese hamster ovary (CHO) cells stably expressing CFTR but not in CHO cells lacking CFTR. Single and whole cell patch clamp recordings from CHO cells confirm that CFTR is the only channel activated by the drugs. Ussing chamber experiments reveal that the apical addition of MPB to human nasal epithelial cells produces a large increase of the short circuit current. This current can be totally inhibited by glibenclamide. Whole cell experiments performed on native respiratory cells isolated from wild type and CF null mice also show that MPB compounds specifically activate CFTR channels. The activation of CFTR by MPB compounds was glibenclamide-sensitive and 4, 4'-diisothiocyanostilbene-2,2'-disulfonic acid-insensitive. In the human tracheal gland cell line MM39, MPB drugs activate CFTR channels and stimulate the secretion of the antibacterial secretory leukoproteinase inhibitor. In submandibular acinar cells, MPB compounds slightly stimulate CFTR-mediated submandibular mucin secretion without changing intracellular cAMP and ATP levels. Similarly, in CHO cells MPB compounds have no effect on the intracellular levels of cAMP and ATP or on the activity of various protein phosphatases (PP1, PP2A, PP2C, or alkaline phosphatase). Our results provide evidence that substituted benzo[c]quinolizinium compounds are a novel family of activators of CFTR and of CFTR-mediated protein secretion and therefore represent a new tool to study CFTR-mediated chloride and secretory functions in epithelial tissues.

Objective:To correlate B-mode ultrasound findings to carotid plaque histology.Design:European multicentre study (nine centres).Material and Methods:Clinical presentation and risk factors were recorded and preoperative ultrasound Duplex scanning with special emphasis on B-mode imaging studies was performed in 270 patients undergoing carotid endarterectomy. Perioperatively, macroscopic plaque features were evaluated and the removed specimens were analysed histologically for fibrous tissue, calcification and ‘soft tissue’ (primarily haemorrhage and lipid).Results:Males had more soft tissue than females (p = 0.0006), hypertensive patients less soft tissue than normotensive (p = 0.01) and patients with recent symptoms more soft tissue than patients with earlier symptoms (p = 0.004). There was no correlation between surface description on ultrasound images compared to the surface judged intraoperatively by the surgeon. Echogenicity on B-mode images was inversely related to soft tissue (p = 0.005) and calcification was directly related to echogenicity (p < 0.0001). Heterogeneous plaques contained more calcification than homogeneous (p = 0.003), however, there was no difference in content of soft tissue.Conclusion:Ultrasound B-mode characteristics are related to the histological composition of carotid artery plaques and to patient's history. These results may imply that patients with distant symptoms may be regarded and treated as asymptomatic patients whereas asymptomatic patients with echolucent plaques should be considered for carotid endarterectomy.

An antibody raised against a peptide in the first nucleotide-binding domain (NBD) of CFTR [1], incorporated into intact rat submandibular acini by hypotonic swelling, inhibited beta-adrenergic stimulated mucin secretion, without affecting cyclic AMP rise. The data are the first to show that a CFTR-antibody-containing cell results in defective stimulation of mucin secretion, as is seen in CF cells, and that this can be reversed by an excessive increase in cyclic AMP.