Dynamic Rheological Behavior of Chitosan/collagen Mixtures

Chitosan and collagen are naturally-derived materials with multiple applications, but their mixtures present phase separation phenomena. This shortcoming in relation to the mixture processing and, obviously, the applications can be overcome by choosing the appropriate composition. Rheological methods have been used to study collagen - chitosan mixtures to highlight their compatibility conditions in solution. Through the use of oscillatory rheometry, the viscoelastic behavior of collagen-chitosan mixtures in 0.5M acetic acid solution was analysed. The storage modulus (G`) was used to describe the elasticity of the material, while the loss modulus (G`) provided information on the viscous behavior of the mixtures.

Analysis and structural characterization of pigments and materials used in Nicolae Grigorescu heritage paintings

The combination of various mobile, non-invasive techniques (IR reflectography technique, optical microscopy, XRF, Raman and NIR spectroscopies) and lab-based devices (FTIR and XPS spectroscopies, SEM-EDX microscopy) lead to the first exhaustive investigation of pigments and materials used by the famous Romanian painter Nicolae Grigorescu in three cultural heritage paintings. The study of a large number of spots and samples allowed a rigorous analysis and a far-reaching insight into his work.

Functional silsesquioxane-based hierarchical assemblies for antibacterial/antifungal coatings

This paper reports the first study on functional silsesquioxane-based hierarchical assemblies containing an ordered distribution of silver nanoparticles with a large number of {111} facets, obtained through sol–gel reaction, intended for antibacterial/antifungal coatings.

Siloxane-based polymers as protective coatings against SO2 dry deposition

The present research was focused on investigating the ability of different siloxane-based polymeric coatings to provide environmental protection to monumental limestone (Repedea from Romania) used in the north-eastern part of Romania for the construction of many stone monuments. Three siloxane-based polymers used throughout the world in protecting stone monuments, namely Lotexan-N, Silres® BS 290 and Tegosivin HL 100 and a newly designed hybrid nanocomposite containing silsesquioxane units (TMSPMA) were selected as polymeric coatings. The ability of the coatings to protect the stone from dry SO2 deposition in the presence of humidity in a standardized accelerated ageing test was determined. A comparative study of the obtained results indicates that the stone samples treated with the new hybrid siloxane-based nanocomposite exhibited improved resistance to degradation after being exposed to a SO2 saturated atmosphere.

Effect of SO2 Dry Deposition on Porous Dolomitic Limestones

The present study is concerned with the assessment of the relative resistance of a monumental dolomitic limestone (Laspra – Spain) used as building material in stone monuments and submitted to artificial ageing by SO₂ dry deposition in the presence of humidity. To investigate the protection efficiency of different polymeric coatings, three commercially available siloxane-based oligomers (Lotexan-N, Silres BS 290 and Tegosivin HL 100) and a newly synthesized hybrid nanocomposite with silsesquioxane units (TMSPMA) were used. A comparative assessment of the data obtained in this study underlines that a better limestone protection was obtained when treated with the hybrid nanocomposite with silsesquioxane units.

Silsesquioxane-based Hybrid Nanocomposite with Self-assembling Properties for Porous Limestones Conservation

The study was concerned with the synthesis and characterization of a silsesquioxane-based hybrid nanocomposite with self-assembling properties intended for monumental porous limestone conservation. Radical polymerization of 3-(trimethoxysilyl)propyl methacrylate in the presence of a primary amine surfactant yielded a new type of hybrid nanocomposite, in which silica was dispersed as domains with typical sizes in the nanometer range. The self-assembling properties of the synthesized composite have been ascribed to the supramolecular assembling abilities of the surfactant, as well as to the combination of linear, ladder, and cage-like fragments of silsesquioxane type. This new sol—gel approach, in which the surfactant makes the pore size of the network more coarse and uniform, avoids cracking while drying inside the stone and thus provides an effective alternative for porous limestone conservation.

Molekulare Reaktionen in kalten Methan-Wasser-Plasmen und die Wirkung von UV-Bestrahlung / Molecular Reactions in Cold Methane-Water Plasma and the Effect of UV Irradiation

After passage of methane-water mixtures through the state of a cold plasma, numerous products were identified, especially aldehydes, ketones, alcohols and acids. Their concentration was dependent on the methane/water ratio. Irradiation with UV light during or after the process gave transformations of the above compounds to more complex combinations. For the formation of ketones, aldehydes, alcohols and acids a detailed mechanism is proposed.