Pharmaceutical and food surfaces of relevant composite materials and the characterization thereof

The main motivation is to understand surface-interface of materials in order to manipulate the systems and then get involved in technology. Particulate and composite materials, used in Pharmaceutical and Food, are subjected to structural modifications during the chain of steps of production and manufacturing processes. The processing objective is often to induce a macroscopic change in order to setup the material for the next processing step. One critical aspect is that the various unit operations meant to adjust the macroscopic properties that invariably induce structural changes at the microscopic scale on the materials. Being unintended, such microscopic changes are also uncontrolled and are the source of the often unpredictable and poorly understood bulk behavior of many particulate materials. It is therefore of critical relevance to develop a fundamental insight at the microscopic structure of such materials, by probing and mapping them at the nanoscale level. This study probes the interface and surfaces of stress-free and stress-induced materials with characterization thereof. Submicron particles are always produced during pharmaceutical and food processing in an uncontrolled and poorly understood manner. The high surface to volume ratio often makes them dominant on the bulk behavior of the in-process materials used for manufacturing. The structural properties controlling in-process response are size dependent, falling over the length scales ranging from nanometers to a few micrometers. In this domain, structural surface mapping is critical to the dispersion and agglomeration control to understand and enable bulk functionality of powders. Working with films has been demonstrated to be an effective way of immobilizing nanoparticulate systems in a dry and uniform manner. The use of polymer–particle composite films results in better reproducibility of in-process systems than the single component counterpart. Therefore, nanoscale mapping of surfaces of such composites results in a more systematic way of characterizing the critical processing attributes of food and pharmaceutical materials that will lead to a higher performance and acceptable shelf-life stability

The catalytic reduction of NO by H-2 on Ru(0001): Observation of NHads species

Adsorption of NO and the reaction between NO and H-2 were investigated on the Ru(0001) surface by X-ray photoelectron spectroscopy (XPS). Surface composition was measured after NO adsorption and after the selective catalytic reduction of nitric oxide with hydrogen in steady-state conditions at 320 K and 390 K in a 30:1 mixture of H-2 and NO (total pressure = 10(-4) mbar). After steady-state NO reduction, molecularly adsorbed NO in both the linear on-top and threefold coordinations, NHads and N-ads species were identified by XPS. The coverage of the NHads and N-ads species was higher after the reaction at 390 K than the corresponding values at 320 K Strong destabilisation of N-ads by O-ads was detected. A possible reaction mechanism is discussed. (c) 2005 Elsevier B.V. All rights reserved

Photon mean free path in the metal nanoparticle system

In the paper comparative evaluation of the photon mean free path in the system of metal nanoparticles and dielectric matrix is performed by means of numerical simulations. As a material of nanoparticles both metals (Ag, Cu) in which the frequency of plasmon resonance falls in the range under study and metals (Al, Ni) in which the plasmon resonance frequency is far from the investigated range have been used. The research has shown that for the studied metals the media based on Al nanoparticles satisfy best the Ioffe-Regel criterion for photons of visible wavelength range

Spectral shaping of lasing active medium with agglomerated nanoparticles of metals and dielectrics

In this paper presented a series of experiments determine the spectral characteristics of random lasing in lasers with agglomerated nanoparticles metals and dielectrics. The data allowed us to establish that, in the active heterogeneous environment, there are various gain effects of lasing the impact of which is determined nanoparticles concentration