Encapsulation of phase change materials with alginate modified by nanostructured sodium carbonate and silicate

The encapsulation of phase change materials (PCMs) as thermal energy storage materials is a big issue. PCM is usually encapsulated to avoid spillage, flammability and its reaction with the surrounding environment to improve its application. In the last decade, various methods have been employed and all kinds of microencapsulated PCM are produced. In this paper, we present a facile route to produce an encapsulated PCM with an organic and inorganic shell. The encapsulated phase change material (PCM) was prepared using a coaxial micro-fluidic system combined with an ionic cross-linking process. The alginate was used as the basic shell and a range of capsules was obtained by modifying the original shell using two inorganic components such as sodium carbonate and sodium silicate. Various samples, each with a different surrounding layer, were prepared by combining alginate calcium (Alg–Ca) as an organic shell with an inorganic component such as alginate calcium carbonate (Alg–CaCO3) and alginate calcium silicate (Alg–CaSiO3). In these experimental works, we have investigated the compatibility and the stability of capsules modified with the inorganic component. The scanning electron microscopy (SEM) technique and optical microscopy were utilized to study the capsule morphology. The chemical composition of the shell was evaluated by Fourier transform infrared spectroscopy (ATR-FTIR), thermogravimetry analysis and SEM coupled with the EDX analysis, and the capsule stability was estimated under an accelerated thermal cycling.     

Correction to: Encapsulation of phase change materials with alginate modified by nanostructured sodium carbonate and silicate

Iranian Polymer Journal - The article listed above was initially published with typo error in first author name.     

Morphological and structural changes in reducing and steam atmospheres of SiO2-supported Rh catalysts

Reduced centres are formed at the silica surface during the pretreatment of Rh/SiO₂ catalysts at high temperatures (500-900°C). These centres can be titrated with steam according to the reaction: reduced centre + H₂O → oxidized centre + H₂. The selective formation of H₂ when catalysts pretreated in D₂ are reacted with H₂O confirms that steam is decomposed during the titration reaction. XRD, TEM and EDX were used to investigate the morphological and structural changes in the catalysts. Owing to the formation of Rh₂Si alloy, the number of reduced centres formed on SiO₂ is much greater than the number found with Rh/Al₂O₃ reduced under similar conditions. This revised version was published online in July 2006 with corrections to the Cover Date.     

Selective steam reforming of aromatic hydrocarbons: IV. Steam conversion and hydroconversion of selected monoalkyl- and dialkyl-benzenes on Rh catalysts

Steam conversion and hydroconversion of a series of monoalkylbenzenes (C₆H₅R, R = C₂H₅, n-C₃H₇, i-C₃H₇, tert-C₄H₉) and of dialkylbenzenes (o- and p-xylenes) are studied at 713 K and atmospheric pressure on supported rhodium catalysts ($\text{Rh}\text{Al}{}_2\text{O}{}_3$, $\text{Rh}\text{SiO}{}_2$ and $\text{Rh}\text{TiO}{}_2$), and compared to the toluene steam dealkylation previously studied on the same catalysts. Three types of reaction, namely dealkylation (CC rupture on the side chain), dehydrogenation (on the side chain), and degradation (i.e., ring opening) account for virtually the whole product spectrum. Isomerization, transalkylation, and dehydrocyclization reactions may, in general, be discounted. In the presence of steam, the main initial product of monoalkylbenzene dealkylation is invariably benzene, but the splitting of the CC bonds in the middle or end of the side chain always increases with conversion. As a rule, the specific activities (per metal site) in dealkylation decrease with the degree of substitution in the alkyl group (primary > secondary > tertiary > quaternary carbon). On the other hand, the specific activities in ring opening remain constant for all the hydrocarbons and even for the benzene. In the presence of hydrogen, multiple CC bond splittings are invariably observed and benzene is no longer, in general, the principal initial product. The activities in ring opening are equally constant, but at a lower level than in steam conversion. These results are in overall agreement with the model of the dual active sites: sites I appear operative for dealkylation and dehydrogenation, whereas ring opening takes place at sites II with a high probability, independent of the alkyl group size. Possible adsorbed species on each type of site are described. An attempt is made to rationalize the effects of assorted selectivity-determining factors (metal particle size, support effects, selective poisons such as S and CO) in terms of electronic or geometric effects.     

Failure of a Vertical Drainage System Installed to Fight the Rise of Groundwater in El-Oued Valley (SE Algeria): Causes and Proposed Solutions

El-Oued Valley suffers from the problem of rising groundwater which affects agricultural and urban areas and degrades all aspects of the socioeconomic life of its inhabitants. This problem, which appeared in the 1980s, is primarily a result of overexploitation of deep groundwater, lack of sanitation network, and discharge of wastewater directly into the unconfined aquifer. To solve this problem, a megaproject was carried out, based on the principle of sewerage, to drain and evacuate excess water after treatment to a discharge site 70 km north of the region. In this project, the blade of groundwater above elevation of 60 m should be drained through wells of a vertical drainage system. However, the expected results have not been achieved in most affected cities, where the groundwater level continues to rise. Herein, we propose a solution to this problem, based on a new explanation of the hydrogeological structure of the unconfined aquifer that drives the rising groundwater to the surface. The main part of this research is based on interpretation of well tests carried out in wells of the vertical drainage system.     

Nonlinear forced vibration of damped plates coupling asymptotic numerical method and reduction models

This work concerns the computation of the nonlinear solutions of forced vibration of damped plates. In a recent work (Boumediene et al. in Comput Struct 87:1508–1515, 2009), a numerical method coupling an asymptotic numerical method (ANM), harmonic balance method and Finite Element method was proposed to resolve this type of problem. The harmonic balance method transforms the dynamic equations to equivalent static ones which are solved by using a perturbation method (ANM) and the finite element method. The numerical results presented in reference (Boumediene et al. in Comput Struct 87:1508–1515, 2009) show that the ANM is very efficient and permits one to obtain the nonlinear solutions with few matrix triangulation numbers compared to a classical incremental iterative method. However, putting a great number of harmonics (6 or greater) into the load vector leads to tangent matrices with a great size. The computational time necessary for the triangulation of such matrices can then be large. In this paper, reduced order models are proposed to decrease the size of these matrices and consequently the computational time. We consider two reduced bases. In the first one, the reduced basis is obtained by the resolution of a classical eigenvalue problem. The second one is obtained by using the nonlinear solutions computed during the first step of the calculus which is realized with the ANM. Several classical benchmarks of nonlinear damped plates are presented to show the efficiency of the proposed numerical methods.     

Unusual radiological diagnosis of pleurisy

Although embolectomy by Fogarty's manoeuvre is the therapy of choice for cardio-arterial and arterio-arterial embolism it might be followed by complications. Our patient showed progressive arterial occlusive disease caused by intimal proliferation. So the decision whether embolectomy or a different therapeutic procedure should be applied must always be done individually. Especially with young female patients the intervention is to be carried out carefully. Alternative methods like percutaneous aspiration embolectomy and fibrinolytic therapy should always be considered.     

Robustness testing of the juice extraction process using a pulsed electrical field

As robustness of any industrial process is an important issue, a standard procedure is used to determine the set point and to minimize the process variability of juice extraction to changes in values of some critical factors. This paper reports work to analyse the efficiency of the pulsed electrical fields carrot juice extraction process even when the control factors undergo slight random variation. The experiments were carried out on a laboratory experimental bench. The work concerned the choice of three factors which are the high voltage level V (kV), the number of pulses and the pulse duration T. Three ‘one-factor-at-a-time experiments’, followed by two factorials designs (one composite, the other fractional), were performed following a well-defined experimental procedure: (1) Fixing the variation domain of the input variables; (2) seeking the optimum set point and (3) analysing the robustness of the process i.e. testing whether the performance of the system remains high even when the factors vary slightly around the set point.     

Triboelectrostatic separation of granular plastics mixtures from waste electric and electronic equipment

The efficiency of the electrostatic separation of insulating granular mixtures depends on the electric charge carried by the particles. The first objective of this work was to characterize the tribocharging properties of various plastic materials in the composition of waste electric and electronic equipment: polyvinyl chloride (PVC), “high-impact” polystyrene (HIPS), acrylonitrile butadiene styrene (ABS), “high-density” polyethylene (HDPE), polycarbonate (PC), polyamide (PA). Thus, in a first series of experiments, 15 samples composed of binary mixtures of above plastics were initially charged in a fluidized bed device, then separated using a free-fall electrostatic separator. The six plastics could be ordered in a specific triboelectric series: PVC, HIPS, ABS, PEHD, PC, PA. The second objective was to evaluate the efficiency of three tribocharging devices: a static charger, a fluidized bed, and a fan-type device. The triboelectrostatic separation experiments performed with four different binary mixtures (PVC/PA, PC/PA, HIPS/PA, and HIPS/ABS) showed that the fluidized bed is the most effective.