One-dimensional (1D) nanostructures of metals, semiconductors and conductive polymers, such as nanowires and nanorods, are very attractive because of their unique electrical, optical, magnetic, and mechanical properties, as well as their potential applications in nanodevices. [1] The synthesis of these nanostructures has been explored by many processes, which are all based on point-initiated uniaxial growth of the crystal or the polymer. One-dimensional arrangements of metal nanoparticles using templates, such as DNA or polymers, have been generated successfully. [2,3] Nickel nanochains were, for instance, synthesized in a solution of poly-(vinyl pyrrolidone). [4] Because of dipolar magnetic interactions, 1D self-assembly is typical for magnetic nanoparticles. [5] We recently reported that Chini clusters (of general formula [Pt 3 (CO) 6 ] m 2À , m = 6) when deposited on flat sup-ports, self-assemble into nanowires. [6] On the other hand, porous hard templates and liquid crystalline phases have been widely used to obtain nanostructured materials. [7][8][9][10][11][12][13][14][15][16][17][18][19][20] In this communication, we first report the 1D self-assembly of platinum nanoparticles in very dilute solution and then show that the organization of much more concentrated nanoparticles into larger nanostructures (fibers or lamellae) can be controlled by using liquid crystals as templates.Platinum nanoparticles are very attractive materials for catalytic and electrocatalytic applications. Ichikawa et al. synthesized platinum and palladium nanowires in mesoporous silica FSM-16. [10,11] These platinum nanowires exhibit unique properties in carbon monoxide (CO) chemisorption and catalysis as well as in magnetism, due to the specific morphology provided by the confinement in the mesoporous channels of the mesostructured silica.To synthesize small Pt nanoparticles, CO reduction of platinum salt (H 2 PtCl 6 ) in aqueous solutions was conducted. At low Pt concentration (up to 10 À3 m) during the slow reduction process the yellow solution turned to pink and the UV-visible (UV/Vis) spectrum displayed a maximum absorption at 537 nm, which increased in intensity until the reduction was complete. Quite unexpectedly, at low Pt concentration, we found that self-assembly of 1.5-2 nm Pt particles into nanofibers (with diameters in the range 5-20 nm) occurred (Figure 1 a). The maximum absorption at 537 nm ( Figure 2) is different from the known plasmon band of individual spherical Pt nanoparticles located around 215 nm. [21,22] The peculiar spectrum shape is probably due to the rodlike assembly of the Pt nanoparticles and their mutual interaction. The spectrum evolution associated with TEM observations at different steps of the reduction process showed that the nanoparticles spontaneously self-as-Figure 1. TEM images of Pt self-assemblies and nanostructured materials obtained by CO reduction of platinum salts in solution or in swollen liquid crystals (SLCs): a,b) in water at concentrations of 5 10 À4 m and 2.5 10 À3 m, respectively, c)...

Résumé -Agrégats bimétalliques Au-Pd et Ag-Pd synthétisés par réduction radiolytique : étude des relations réactivité/structure en hydrogénation sélective du buta-1,3-diène -Des catalyseurs Ag-Pd et Au-Pd (sous forme d'alliage ou de structure coeur-coquille) ont été synthétisés par réduction radiolytique (rayons gamma ou faisceau d'électrons). L'étude de l'hydrogénation sélective de buta-1,3-diène par ces différents nanoagrégats déposés sur alumine a permis de déterminer les effets de la composition et de la structure sur les performances catalytiques. Les nanoagrégats Au-Pd et Ag-Pd montrent des propriétés catalytiques très différentes : alors que l'activité en hydrogénation est modifiée dans des systèmes Au-Pd sans changement de sélectivité dans la formation des butènes, d'importantes variations de sélectivité sont observées pour les nanoagrégats Ag-Pd déposés sur alumine. Abstract -Bimetallic Au-Pd and Ag-Pd Clusters Synthesised by γ γ or Electron Beam Radiolysis and

TiO2 nanoparticles synthesized by the sol-gel method and doped with Ag were characterized by SEM, EDAX, FTIR, BET, XRD and TEM, then tested in the photocatalytic degradation of methylene blue (MB) under UV irradiation. The experimental results indicate that the average size of the raw particles was 10 nm, and their size was increased by calcination. The photocatalytic degradation of MB on nanostructured TiO2-Ag shows a high degradation efficiency upon the addition of a photosensitizer. A parametric study of the process was performed and has revealed the optimal value of the photocatalyst dose (0.3 g L−1) at a MB concentration of 4 ppm. Afterwards, the effect of acetone as a photosensitizer was studied. A MB degradation mechanism was proposed to explain the synergy between the TiO2 and the silver nanoparticles in the degradation performance. Under the optimal experimental conditions, at photosensitizer doses of 0.1 and 0.2%, yields of 92.38% and 97.25% MB degradation were achieved, respectively. Kinetic models showed that, at 0.1% acetone concentration, the data fit the pseudo-first-order model, while at 0.2% acetone, the photodegradation mechanism fits a second-order model. The values of the apparent rate constants indicate that the reaction rate increased between 24 and 40 times in the presence of acetone on TiO2 and TiO2-Ag. The addition of acetone modified the photodegradation mechanism and the Ag-doped samples became more active. The results of recycling tests using calcined TiO2-Ag material clearly show that the material was highly photocatalytically stable for the MB degradation. According to experimental results, the dye degradation decreased from 97.25% to 92.39% after four consecutive cycles. This simple approach could be applied for the advanced cleaning of wastewater contaminated with dyes, in the perspective of its reuse.

The effect of storage time on the composition of the olive and sunflower oils has been investigated. It were studied parameters like free fatty acids (FFA), anisidine value (AV), iodine value (IV), saponification number (SN) and identification of the molecular structure through FT-IR method. During storage (48 months) an increasing in the values of parameters FFA and AV took place that measures the oxidative degradation of oils. The oxidative stability of olive oil stored at room temperature was less than of sunflower oil. Also, significant differences were found among the olive oil and sunflower oil during storage period.

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CeO2/ZnO-based photocatalytic materials were synthesized by the sol-gel method in order to establish heterojunctions that increase the degradation efficiency of some types of antibiotics by preventing the recombination of electron–hole pairs. The synthesized materials were analysed by XRD, SEM, EDAX, FTIR, and UV-Vis. After several tests, the optimal concentration of the catalyst was determined to be 0.05 g‧L−1 and 0.025 g‧L−1 for chlortetracycline and 0.05 g‧L−1 for ceftriaxone. CeO2/ZnO assemblies showed much better degradation efficiency compared to ZnO or CeO2 tested individually. Sample S3 shows good photocatalytic properties for the elimination of ceftriaxone and tetracycline both from single solutions and from the binary solution. This work provides a different perspective to identify other powerful and inexpensive photocatalysts for wastewater treatment.

A new catalytic mixture of nanosized dioxide (CeO 2 ) and zinc oxide (ZnO) powders have been synthesized by surfactant-assisted solvo-thermal route, characterized and evaluated for photocatalytic activity. The prepared catalysts were characterized by TG, XRD, SEM and EDAX methods. SEM analysis showed that the catalyst particles have spheroidal shape and their sizes range from 50 to 80 nm, organised as uniform distributed aggregates with large surface area, leading to the existence of a large number of defects. The photocatalytic activity of these materials was evaluated by UV-Vis spectroscopy for degradation of methylene blue (MB) and 4'-(1-methyl-benzimidazoyl-2)-phenylazo-2"-(8"-amino-1"-hydroxy-3",6"-disulphonic)-naphthalene acid (PMBH) in water.

The kinetics of the ion-exchange process with iron on pretreated analcime has been investigated in different conditions of temperature, time and concentration of the exchange solution. The performances of the catalyst were analyzed using the Table Curve software. The mathematical model corresponding to the characteristic equation provides a good arrangement of the experimental points on the responding surface, simplicity of the characteristic equation and a good determination coefficient that is near unity.