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A healthy breath is mainly composed of water, carbon dioxide, molecular nitrogen, and oxygen and it contains many species, in small quantities, which are related to the ambient atmosphere and the metabolism. The breath of a person affected by lung cancer presents a concentration of 1-propanol higher than usual. In this context, the development of specific sensors to detect 1-propanol from breath is of high interest. The amount of propanol usually detected on the breath is of few ppb; this small quantity is a handicap for a reliable diagnostic. This limitation can be overcome if the sensor is equipped with a pre-concentrator. Our studies aim to provide an efficient material playing this role. This will contribute to the development of reliable and easy to use lung cancer detectors. For this, we investigate the properties of a few hydrophobic porous materials (chabazite, silicalite-1, and dealuminated faujasite). Hydrophobic structures are used to avoid saturation of materials by the water present in the exhaled breath. Our experimental and simulation results suggest that silicalite −1 (MFI) is the most suitable structure to be used as a pre-concentrator. [ABSTRACT FROM AUTHOR]

In this work tackles experimentally and by COMSOL Multiphysics (C.M) numerical modeling using 3 ω method, the effects of temperature on thermal conductivity of MWCNT/Glycerol and MWCNT/(50 %Water/50 %Glycerol) nanofluids. The experiments were performed at temperatures ranging from 20 °C to 40 °C employing different base fluids (including Water, Glycerol, Ethylene Glycol, 50 %Water/50 %Glycerol) and nanofluids (MWCNT/Glycerol and MWCNT/(50 %Water/50 %Glycerol)), to extract the influence of MWCNT nano-objects on the thermal conductivity behavior of the base fluids. Our approach is based on the heat transfer process between the fluid sample and sinusoidal heating source using synchronous detection to measure the conductive–convective exchange coefficient. We used COMSOL Multiphysics to design the experimental set-up and to reproduce the results of thermal conductivity of the different nanofluid samples. Then the experimental values of thermal conductivity obtained by 3 ω method are compared with those reproduced by COMSOL Multiphysics simulation and semi-empirical models. [ABSTRACT FROM AUTHOR]

Silver nanoparticles (Ag NPs) coated by an aqueous emulsion of copolymer were elaborated in a short time using polyol process and microwave (MW) heating. This approach is based on reducing AgNO3 powder in the presence of two main components; ethylene glycol as a dispersed medium and an industrial copolymer (latex) as protecting agent. The structural, morphological and optical properties of the prepared silver nanoparticles have been investigated by UV–Vis spectroscopy, Infrared Spectroscopy (IR), X Ray Diffraction (XRD) and Transmission Electron Microscopy (TEM). It was found that all these properties are strongly correlated to the latex copolymer concentration and the MW heating process. The absorption band was determined by UV Visible spectra, showing several bands (localized surface Plasmon band) in the visible region at wavelengths between 410 and 430 nm. The TEM analysis of the obtained products indicates the presence of straight nanowires and dispersed, spherical silver nanoparticles with well-controlled size ranging from 7 to 20 nm. The X Ray Diffraction showed that silver nanoparticles synthesized exhibit face centered cubic (fcc) structure. The infrared spectra show the strong coordination between the surface of silver particles and molecules of latex by O–H and C=O groups. Antimicrobial activity of latex/Ag NPs against E. coli, Staphylococcus aureus, and Pseudomonas aeruginosa has been also demonstrated. The results indicated that latex/AgNPs may damage the structure of bacterial cell membrane. [ABSTRACT FROM AUTHOR]

Nickel nanoparticles stabilized in aqueous emulsion of copolymers were prepared in a few minutes using polyol assisted-microwave (MW) process. This approach based on the reduction of metal salt (NiCl2·6H2O) in the presence of low concentration of hydrazine hydrate (N2H4·H2O) using a commercial copolymer (latex) as both, reducing and stabilizing agents. The reaction parameters such as the precursor concentration, copolymer and MW power affect significantly the reaction rate and the shape/size (2.5 nm to 7 nm) of Ni nanoparticles. Ni NPs were stored at room temperature for approximately 6 months without any visible change, which indicate the important role of latex copolymer as a good stabilizer for Ni NPs, The structural and optical properties have been studied separately using UV–Visible spectroscopy, Transmission Electron Microscopy (TEM) and Energy-Dispersive X-ray Spectroscopy (EDXs). TEM images using high magnifications identified the Ni NPs as spherical shapes. The FTIR spectra indicate that Ni nanoparticles attached to the copolymers (latex) at the surface by the stretching vibration of O–H bond, which gives crucial information on the interface structure Ni NPs/Latex marked by a reduced coupling between spins at NPs surfaces. Magnetic properties were demonstrated using SQUID (Quantum Design Squid/VSM). The shift observed in hysteresis loop (M–H) measured at 2 K due to the spin–spin reduced coupling at the nanoparticles surfaces, which gives spin-glass like behavior in the system. In other hand, the zero-field-cooled (ZFC) and the field-cooled (FC) measurements under magnetic field of 100 Oe exhibited the blocking temperature TB that strongly depends on Ni particle sizes. [ABSTRACT FROM AUTHOR]

Palladium nanoparticles were prepared in a few minutes using polyol assisted-microwave process. This synthesis based on the reduction of metal salt (kPdCl) in ethylene glycol medium in presence of an aqueous emulsion of copolymers (latex) as a reducing and stabilizer agent. The products were characterized by UV-Vis spectroscopy infrared spectroscopy transmission electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, selected area electron diffraction patterns, and high-resolution transmission electron micrographs. We have found spherical homogeneous Pd nanoparticles with narrow particles size distributions. In addition, we used Pd-latex-EG nanofluid emulsion for catalyzing organic reactions including Suzuki, Heck and the Sonogashira reactions. As a result, we have successfully demonstrated the crucial effect of latex copolymer for reducing and capping Pd nanoparticle. We point out that the presence of the polymer molecules don't affect the catalytic effect which mainly due to the Pd metallic nanoparticles. [ABSTRACT FROM AUTHOR]

We study calcium silicate glass of composition (CaO)X(SiO2)(1−X), where X = 40–70 mol%, by means of molecular dynamics for different cooling rates between 1011–1013 K s−1. The thermodynamic and kinetic properties of calcium silicate materials are determined, discussed, and correlated to local structures at short and intermediate range orders and to the potential energies of the oxygen atoms. We show that the amount of non-bridging oxygens and the appearance of free oxygens are related to the increase of the glass transition temperature for an increasing CaO content. Our results are analyzed and discussed in connection with the available experimental data. [ABSTRACT FROM AUTHOR]

Silver nanoparticles were synthesized by the reduction of the silver nitrate (AgNO) using the latex copolymer in ethanol solution under microwave (MW) heating. The reaction parameters such as silver precursor concentration (from 0.005 to 0.1 g/l) and MW power (200-800 W) significantly affect the formation rate, shape, size and distribution of the silver nanoparticles. A significant reduction of irradiation time was observed when the MW energy is compared to conventional thermal reduction processes. The prepared silver nanoparticles show uniform and stable sizes from 5 to 11 nm, which can be stored at room temperature for approximately 12 months without any visible change. These peculiarities indicate that the latex copolymer is a good stabilizer for the silver nanoparticles. The optical properties, morphology, and crystalline structure of the silver-latex copolymer nanocomposites were characterized by the Ultraviolet-Visible spectroscopy, transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The study of the TEM images at high magnifications identified the silver nanoparticles as face-centered cubic (fcc) structure with spherical and hexagonal shapes. [ABSTRACT FROM AUTHOR]

Highly stable and monodispersed silver nanoparticles with uniform morphology have been successfully prepared by microwave (MW) irradiation within a few seconds from the mixture of silver nitrate, ethanol and latex copolymer. The aqueous emulsion of latex copolymer acts as both reducing and stabilizing agent. To the best of our knowledge, it was the first time that the effect of MW irradiation time and latex concentration on the silver nanoparticle preparation and properties was analyzed. The formation of silver nanoparticles was confirmed by Ultraviolet-visible spectroscopy and transmission electron microscopy (TEM). The UV-Vis spectra are marked by the characteristic surface plasmon absorption band in the range 410-420 nm. From TEM images, silver nanoparticles were observed to be spherical with sizes ranging from 4 to 10 nm. Electron diffraction patterns on selected area, indicated that the silver nanoparticles are crystalline with face centered cubic structure. [ABSTRACT FROM AUTHOR]

In this work, we synthesized and characterized mesoporous thin films of SiO2and NiTiO3structured by a surfactant called Brij58. These films were fabricated by the method of dip coating and the best conditions for well-structured thin films were investigated as a function of surfactant concentration and different types of substrates. These films have been characterized by X-ray reflectivity which was calculated using the matrix formalism. We demonstrated that the silicon substrate had a great effect on the structure and porosity of the fabricated films for both SiO2and NiTiO3. Furthermore, we found that mesoporosity has been increased as a function of the surfactant concentration in the solution. This experimental procedure allows also to produce NiTiO3powders which have been characterized by X-ray diffraction. The XRD coupled to the crystallographic software “Maud”shows that the samples are constituted by 98, 2% NiTiO3powders. [ABSTRACT FROM AUTHOR]

TiO2, ZnO and ZnO/TiO2thin films have been prepared by radio frequency magnetron sputtering method under different temperatures. Their photo catalytic activities have been investigated. The structural of the thin films were characterized by X-ray diffraction and Raman spectroscopy. The photo catalytic activities of TiO2and ZnO/TiO2samples were evaluated by the photo decomposition of methylene blue. We note that the structural proprieties of the thin films showed a perfect crystallization along the (002) for ZnO, Rutile (110) for TiO2and Anatase (101) for TiO2. The experimental results show that the bilayer ZnO/TiO2were the most efficient photo catalysts compared to the layer of TiO2. This increased catalytic effect can attributed to the interface between the ZnO layer and the TiO2one, which modify significantly the chemical potential of the bilayer. [ABSTRACT FROM AUTHOR]

DIAM (Dispositif d'Irradiation d'Agrégats Moléculaires) is a new experimental setup devoted to investigate processes induced by irradiation at the nanoscale. The DIAM apparatus is based on a combination of techniques including a particle beam from high-energy physics, a cluster source from molecular and cluster physics, and mass spectrometry form analytical sciences. In this paper, we will describe the first part of the DIAM apparatus that consists of an ExB double spectrometer connected to a cluster ion source based on a continuous supersonic expansion in the presence of ionizing electrons. This setup produces high intensities of energy-and-mass selected molecular cluster ion beams (1000 s of counts s-1). The performance of the instrument will be shown through measurements of 6-8 keV beams of protonated water clusters, (H2O)nH+ (n = 0-21) and mixed protonated (or deprotonated) water-pyridine cluster ions: PyrH+(H2O)n (n = 0-15), Pyr2H+ (H2O)n (n = 0-9), and (Pyr-H)+ (H2O). [ABSTRACT FROM AUTHOR]

Ionization and fragmentation of water and uracil molecules was studied both by electron and proton impact. A special coincidence technique allows on an event by event basis the investigation of product ions formed upon the collision of protons with neutral molecules including the identification of the charge state of the projectile. This enables the characterization of the ionization processes occurring, i.e. direct ionization, single electron capture or double electron capture for 0, 1 or 2 electrons that are transferred from the target to the projectile, respectively. For uracil the fragmentation patterns obtained by electron and proton impact ionization reveal close similarities and indicate a comparable amount of excitation for the two different ionization mechanisms at high enough projectile energies. [ABSTRACT FROM AUTHOR]