Silanization of natural Na+-maghnite algerian clay pre-intercalated with a cationic alkylphosphonium salt

In this investigation sodium Maghnite (Na⁺-Mag) clay was functionalized by the combination of two consecutive treatments. The first treatment was the intercalation of the clay by means of a cationic surfactant; namely: 1-butyl (triphenyl)phosphonium chloride (BTPPC). In the second step, the alkylphosphonium-modified clay was functionalized with three silane coupling agents; namely: N-(2-Aminoethyl)-3-aminopropyltrimethoxysilane (AEAPTMS), 3-methacryloxypropyltrimethoxysilane (MPTMS) and 3-glycidoxypropyltrimethoxysilane (GPTMS) in order to introduce functional groups on the silicate layers. The modified clays were fully characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), solid state ²⁹Si NMR and contact angle measurements. The FT-IR results demonstrated the presence of alkylphosphonium cations and the grafting of the silane coupling agents on the clay surface. The XRD analysis showed an increase of the d₀₀₁ value with the introduction of alkylphosphonium cations (d-value～2?nm). Nevertheless, no variation of the interlayer distance was observed after the silanization processes. Furthermore, the TGA characterization indicated a successful intercalation and silanization of the clay. The ²⁹Si NMR analysis of the different modified materials showed the presence of two additional resonance signals T³ and T² corresponding to [RSi*(OSi)₃] and [RSi*(OSi)₂(OH)] species respectively, which confirmed the successful grafting of the silanes on the clay surface. The contact angle results revealed that the polar and specific components of the surface energy of the clay can be enhanced after the silanization treatment.     

Preparation of dendrimer polyol/mesoporous silica nanocomposite for reversible CO2 adsorption: Effect of pore size and polyol content

This paper focuses on the synthesis of polyol/MCM-48 nanocomposite materials with different percentages of polyalcohol dendrimer H20. The obtained materials were used for CO₂ adsorption. CO₂-TPD analysis showed that the samples containing 1 and 3 wt% of H20 dendrimer have low CO₂ adsorption capacity due to the occupation of active sites, The sample prepared with 0.5 wt% of H20 dendrimer exhibited higher adsorption capacity and thermal stability. The affinity toward CO₂ was found to be mainly due to the presence of organic moiety within the MCM-48 pores.     

An ASPIRE-based method for quality requirements identification from business goals

Quality requirements are the main drivers for modeling and evaluating software quality at an early stage, and ASPIRE is an engineering method designed to elicit and document the quality requirements of embedded systems. This paper proposes an extension to ASPIRE to identify quality requirements from the business goals of the organization and ensure their traceability. This extension includes a set of added components created from the main concepts of the SOQUAREM methodology, including the BMM (business motivation model), derivation rules, the quality attribute utility tree, the quality attribute scenario template, the quality attribute documentation template, and ISO 9126. The applicability of the extended method is illustrated with a wireless plant control system as an example.     

Parameters identification of photovoltaic solar cells and module using the genetic algorithm with convex combination crossover

To design a high-performance photovoltaic (PV) system, the parameters extraction of solar cell models is exceedingly crucial. A new variant of the genetic algorithm (GA) called Genetic Algorithm with Convex Combination Crossover (GACCC) is proposed to identify the unknown electrical parameters of different solar cell models, i.e. single diode, double diode, and PV module. GACCC is achieved by integrating a new crossover operation to maintain a good balance between the intensification of the best solutions and the diversification of the search space. To test the proposed GACCC, we have compared it to the basic GA and with other literature techniques. The results indicate a high performance of developed approach GACCC and a high accuracy of estimated parameters. In addition, the efficiency of the results is confirmed by the good agreement between the experimental I-V data and the simulated results in all cases.     

Analysis and mapping of the heating and cooling degree-days for Morocco at variable base temperatures

The purpose of this study is to evaluate, analyse and draw up maps of the heating and cooling degree-days (CDD) for Morocco. Data from 37 weather stations around Morocco during 10 years (2000–2009) were used. The mean heating and CDD at base temperatures of 18°C and 21°C, respectively, were presented. The effect of the geographical conditions such as latitude, longitude and elevation on the heating and CDD was investigated using the regression approach and the counter maps were performed using the digital elevation model of Morocco. To provide more accurate information to building designers and engineers, the heating and CDD were also calculated and tabulated for cities representing the six Moroccan climatic regions at different base temperatures varying from 12°C to 20°C for heating and from 20°C to 28°C for cooling, with a step of 1°C.     

Comparative behaviour of goat β and αs1-caseins at the air–water interface and in solution

Here we present a comparative study of caprine β- and α_s1-caseins behaviours at the air–water interface and in solution. Both caseins were purified from the milk of a single goat homozygous at the α_s1- and β-Cn loci, with a high degree of purity (98%). Physical measurements (ellipsometry, surface pressure and surface rheology) were performed at the air–water interface, whereas SAXS measurements were performed on casein solutions. Our results clearly show that self-organizations, both at the air–water interface and in solution are different for β- and α_s1-caseins. β-casein is unfolded in solution and forms a network at the interface, while α_s1-casein forms compact objects in solution and is organised in fluid domains at the interface. We also show that the presence of Ca²⁺ in the subphase strongly disturbs the interfacial layer formed by the caseins. It is elsewhere worth noting that in solution, the aggregation of α_s1-casein induced by calcium ions is associated with a pronounced change in the molecular structural organisation of the protein, which seems to adopt, in these conditions, an unfolded structure.     

Human Body Communication In-Vivo Measurement Using Different Test Equipment

Human body communication is non-radio frequency technique of wireless body area network, wherein the human body is used as a communication medium in two coupling methods namely: capacitive and galvanic coupling. HBC is relatively new method and in full development, given the large number of scientific publishing works depending on different setup and equipment. Even that it remains controversial with no consensus in terms of propagation characteristics and behavior mechanism. This paper deals with the common used test equipment and configuration attempting to provide a complementary information about HBC channel characterization issue. For that, in vivo measurements were carried out using several assembling of equipment in different scenarios, considering the conventional inspected parameters (channel length, transverse distance and balun insertion scenarios). The measurements were conducted in both frequency and time domain using primarily spectrum/vector network analyzer and digital oscilloscope respectively. Thus, in addition to transmission losses between transceivers across the channel (calculated path loss factor), phase angle information are considered over the operating frequency band to assert the non-dispersive HBC channel nature. Further harmonic distortion effect is shown, then high transmission power for the signal of interest is attributed to HBC methods according to the calculated total harmonic distortion THD metric, even harmonics resulting from the channel non-linearity characteristics or transceivers signal/apparatus imperfections. The experimental setups highlights the important to consider the precise criteria for measurement purpose, thus leading using the most appropriate test apparatus.