Pristine halloysite nanotubes (HNTs) were studied by thermogravimetry (TG) up to 800°C. Etching of alumina from inside the tube (causing a significant increase in tube lumen) was realized by treating the material with an acidic H 2 SO 4 solution at 50°C. Both materials were characterized by TG-FTIR techniques and their thermal behaviors were compared with that of kaolinite. The coupling of TG with FTIR enables to detect the gases evolved during the TG experiments, thus confirming that only pristine HNTs undergo dehydration with the loss of interlayer water molecules at around 245°C, while dehydroxylation occurs in all these materials in close temperature ranges around 500°C. TG runs at five different heating rates (2, 5, 10, 15 and 20°C min -1 ), was carried out in the same experimental conditions used for the thermal analysis study with the aim to investigate dehydration and dehydroxylation kinetics using some isoconversional methods recommended by the ICTAC kinetic committee, and thermogravimetric data under a modulated rising temperature program. Finally, the results of the kinetic analysis were discussed and explained in terms of the strengths of the hydrogen bonds broken during these processes.

Halloysite nanotubes (HNTs) and salicylic acid (SA) are natural substances widely used in different fields. HNTs are very promising as nanocarriers because of their biocompatibility, atoxicity, anti-inflammatory properties and capacity to maintain the biological activity of immobilized enzymes. Due to its bactericidal and antiseptic properties, salicylic acid (SA) is used in pharmaceutical formulations, and as an additive for preserving foods and cosmetics. In this study, we set up a procedure for the loading of HNTs with SA for their possible application in active food packaging. Pristine HNTs were studied together with acidic etched HNTs with enlarged internal lumen, and various pH values for the loading solutions were tested in order to obtain the maximum loading. The HNTs - empty and loaded with SA - were characterized by TG-FTIR, FTIR SEM, STEM and nitrogen adsorption/desorption isotherms measurements. We obtained a maximum loading of 10.5% (w/w), using HNTs pretreated with H2SO4 2 M at 25°C for 48h and a solution of sodium salicylate at pH 8. We also characterized the interaction of SA-HNTs at a molecular level by combining ATR-FTIR measurements and periodic density functional theory (DFT) calculations. We believe that the information on the SA/HNT complexes derived from our research should help to improve the current knowledge of SA-clay interactions. In addition, it should be of interest for environmental and earth sciences since SA is used to model natural organic matter (NOM) in both experimental and theoretical studies of NOM adsorption on different kinds of mineral surface

Nanoindentation experiments carried out with atomic force microscopes (AFMs) open the way to understand size-related mechanical effects that are not present at the macro- or micro-scale. Several issues, currently the subject of a wide and open debate, must be carefully considered in order to measure quantities and retrieve trends genuinely associated with the material behaviour. The shape of the nanoindenter (the AFM tip) is crucial for a correct data analysis; we have recently developed a simple geometrical model to properly describe the tip effect in the nanoindentation process. Here, we demonstrate that this model is valid in indentation of both soft and hard, or relatively hard, materials carried out by two distinct, commercially available, AFM probes. Moreover, we implement the model with a data interpretation approach aimed at preventing underestimation of the tip penetration into the material. Experiments on soft polymeric materials (poly(methyl methacrylate) and polystyrene) and hard or relatively hard (Si, Au, Al) materials are reported. The results demonstrate that true hardness data can be attained also in shallow indentations and that the appearance of size effects strongly depends on data interpretation issues. In addition, we report on stiffness data measured on the considered materials during their nanoindentation.

Cocoons produced by different strains of Bombyx mori larvae were investigated by a combination of several high- and low-resolution 1H and 13C solid-state NMR techniques in order to characterize and compare their dynamic behavior at a molecular level. A detailed interpretation in terms of molecular motions in these very complex systems was possible thanks to the integrated analysis of different relaxation measurements and high-resolution selective experiments. Untreated cocoons of all strains were found to be mainly constituted by two different types of rigid domains and by a third one, more mobile, due to physisorbed water molecules. Dynamic processes in the MHz and kHz ranges were characterized by means of different 1H and 13C relaxation times. Cocoons arising from different strains exhibit a different content of physisorbed water and also slightly different dynamic behavior, especially in the MHz regime.

Several experimental techniques have been used to investigate the chemical physical properties of new functionalized ultra-small iron oxide nanoparticles (USPION), which are of interest for biomedical applications. Methods: The chemical composition of oleate-coated iron oxide (OA-NPs) and cystine-coated iron oxide (Cy-NPs) nanoparticles was investigated by means of analytical methods and Fourier Transform Infrared (FT-IR) spectroscopy. Atomic Force Microscopy (AFM) and Transmission Electron Microscopy (TEM) investigations, at high and low resolutions, on both OA-NPs and Cy-NPs, were performed to investigate their morphology. The magnetization and susceptibility behavior of OA-NPs and Cy-NPs were studied by SQUID magnetometry. Results: The combination of different experimental techniques was of help in characterizing the chemical structure of both magnetic core and surface-coating of OA-NPs and Cy-NPs. AFM/TEM images and magnetic measurements were analyzed in terms of crystallinity, polidispersity, average magnetic core size and coating effects of these nanoparticles. Conclusions: These results show that the preparations reported in the present paper are effective in obtaining nanoparticles of 4 nm magnetic core size and the procedure is highly reproducible. The presence of the external cystine shell, fundamental for biomedical applications, does not affect the polidispersity, the crystallinity or the average core size. Moreover, similar values of the average core dimensions have been obtained by three different techniques (AFM and TEM images, magnetic measurements