Synthesis of polypyrrole/Fe-kanemite nanocomposite through in situ polymerization: effect of iron exchange,acid treatment,and CO<Subscript>2</Subscript> adsorption properties

This paper focuses on the synthesis of polypyrrole/Fe-kanemite nanocomposites by in situ polymerization of pyrrole. Different percentages of PPy/Fe-kan have been prepared and tested for the CO₂ adsorption. Fe-exchanged kanemite was prepared using various iron contents and used as an oxidant for the preparation of PPy/Fe-kan nanocomposite. The obtained materials were characterized using various techniques such as X-ray diffraction (XRD), Fourier transform infrared spectroscopy, ultraviolet–visible (UV–vis), thermogravimetric analysis TGA, energy dispersive X-ray analysis, scanning and transmission electronic microscopy (SEM, TEM). Based on the XRD and UV–vis analysis, the exchange process leads to the formation of various iron species on the external and internal surface. The thermal stability of PPy/Fe-kan was improved and increased in the following order PPy/Fe-kan (1%) > PPy/Fe-kan (3%) > PPy/Fe-kan (5%) > PPy/Fe-kan (10%) > PPy. SEM and TEM analysis show that the nanocomposite particles have spherical morphology with a high dispersion of the Fe-kanemite in the polymer matrix. CO₂ adsorption at 0 and 15 °C was carried using a volumetric method, and the recorded isotherm indicated that the CO₂ adsorption capacity of PPy/Fe-kan can be enhanced through modification by polypyrrole. The unmodified Na-kanemite has low CO₂ adsorption capacity around 0.05 mmol g^?1 at 15 °C, while the PPy/Fe-kan (5%) nanocomposite presented the best CO₂ adsorption capacity around 1.7 mmol g^?1 at 0 °C under low pressure that is mainly attributable to physical adsorption.     

Plane-compression properties of microcellular injected polypropylene using gas counter pressure and core-back expansion process

Microcellular Polypropylene (PP) was obtained using Chemical Blowing Agents (CBA) in a injection process combined with Gas Counter Pressure (GCP) and core-back expansion molding. Two different types of PP, neat and charged, were mixed with a fixed proportion of CBA and injected into a plate, obtaining structural foams with a foamed core and solid outer skins. After, the plate morphology is analyzed to evaluate the main morphological parameters, such as cell size and thickness of the outer skin. The results show that the type of CBA has a great influence on the cell size. Finally, low velocity plane compression tests were carried out in the structural foams at a fixed strain rate to obtain the Young’s modulus of the foamed core and also the whole structure, using some theoretical approaches to evaluate the effect of foam density in the obtained results.     

A new efficient lightweight and secure image cipher scheme

Multimedia Tools and Applications - The protection of multimedia content has become a key area of research, since very often a user’s privacy and confidentiality can be at risk. Although a...     

Impact of Thermal and Chemical Pretreatments on Physicochemical,Rheological, and Functional Properties of Sweet Potato (Ipomea batatas Lam) Flour

The impact of thermal and chemical pretreatments on the physicochemical, rheological, and functional properties of sweet potato flour was investigated. The chemical pretreatment consisted in dipping peeled sweet potatoes in 1 % (w/v) calcium chloride (CaCl₂), while the thermal pretreatment was achieved by blanching them in tap water at 90 °C for 1 min. Composition in flour moisture, protein, fat, non-reducing sugars, and starch was determined using standard methods. Particle size, color, gelatinization, and rheological properties were analyzed. The water absorption index (WAI) and water solubility index (WSI), as well as the swelling capacity (SC) and sorption isotherms, were determined. The reducing sugar content of sweet potato flour was slightly higher in CaCl₂-pretreated (SSPCaCl₂) samples than that in blanched (SSPB) and control (SSP) samples. However, the lightness of the SSPB sample was lower than that of the SSPCaCl₂ and SSP samples. SSPCaCl₂ sample had the higher value of enthalpy of gelatinization and elasticity modulus G′. The SC was higher in blanched samples. A slight increase in the constant of water binding energy (C _BET) was observed after the CaCl₂ treatment and a marked increase for the blanched sample. Owing to the differences induced by blanching and CaCl₂ pretreatments, CaCl₂-pretreated flour samples are more suitable for bread-making processes and can also be used in food formulations.     

Grover’s algorithm and the secant varieties

In this paper we investigate the entanglement nature of quantum states generated by Grover’s search algorithm by means of algebraic geometry. More precisely we establish a link between entanglement of states generated by the algorithm and auxiliary algebraic varieties built from the set of separable states. This new perspective enables us to propose qualitative interpretations of earlier numerical results obtained by M. Rossi et al. We also illustrate our purpose with a couple of examples investigated in details.     

Influence of various chemical treatments on the interactions between hemp fibres and a lime matrix

In this paper, results presented concern both the chemical and physical behaviours of hemp fibres in lime-based mineral matrix in order to better understand the role of chemical modifications of cellulosic fibres in the evolution of the macroscopic properties, essentially mechanical ones, of such composite materials. The role of fibres surface treatment has been also studied through various chemical treatments applied on hemp fibres. In a first step, the influence of such treatments on the fibre characteristics has been investigated by several means, such as scanning electron microscopy, thermal analysis, X-ray diffraction and FTIR spectroscopy, in order to evaluate their consequences on the fibre behaviour itself. Secondly, an attempt to characterise the influence of the various chemical treatments of fibres on the mechanical behaviour of hemp reinforced lime-based composites has been completed by a three points bending testing campaign. According to the results, it seems that the modifications induced by specific chemical treatments (EDTA, NaOH) on fibres play a major role in the strengthening of the lime/fibres interface but also in the improvement of the overall stiffness of the composite (with respect to the one reinforced by untreated fibres) most probably related to a specific stiffening process of the fibre itself.     

Synthesis of the RuSr2GdCu2O8±z Compound at Ambient Pressure Through a Solid State Reaction, Melts and Sol-Gel by Acrylamide Polymerization Methods

The RuSr₂GdCu₂O_8±z (Ru-1:2:1:2) compound, was synthesized at ambient pressure by solid-state reaction, melts, and sol-gel by acrylamide polymerization methods with the following intervals of temperature reaction: T= 960–1015°C, T=1450°C, 135–980°C respectively. Differential Thermal Analysis (DTA) result gave us an idea about the temperature interval where the Ru-1:2:1:2 compound was formed. Results of X-Ray powder Diffraction (XRD) data show the formation of the Ru-1:2:1:2 phase, which crystallizes in a tetragonal structure with a space group P4/mmm. The synthesis of the Ru-1:2:1:2 compound by the melts route was found to be faster than the other synthesis methods. Studies by the Scanning Electron Microscopy (SEM) technique gives a particle size around 1–6 μm. The chemical compositions of the samples were obtained by Energy Dispersive X-ray (EDX) spectroscopy. The resistance vs. temperature data of the samples annealed in oxygen flux for 6, 12, 41 and 64 h, at T=960°C, shows a semiconductor behavior.     

Interferometric method for the analysis of dendrite growth and shape in 3D extended patterns in transparent alloys

In the frame of the DECLIC project of the French Space Agency (CNES), a specific device dedicated to the in situ and real time observation of directional solidification of transparent systems in 3D configuration has been developed. A method based on interferometric analysis is presented to quantitatively characterize the shape and growth of dendrites so that measurements of critical parameters such as tip radius and growth rate of individual dendrites belonging to extended patterns are enabled. First results obtained on a succinonitrile ? 0.1 wt% camphor alloy are analysed. The accuracy of measurements and quality of the shape reconstruction are discussed through the comparison of the dendrite contours obtained with different modellings of the dendritic shape (parabolic, parabolic corrected by a 4^th order term, power-law).     

Propagation D'un Rayon Lumineux à Travers Un Milieu Isotrope Inhomogène Mobile

Abstract

A l'aide d'une méthode géométrique que l'on démontre être équivalente au traitement physique dans un espace plat, nous obtenons une solution rigoureuse donnant la trajectoire d'un rayon lumineux se propageant dans un milieu inhomogène mobile.