Novel polysiloxane and polycarbosilane aerogels via hydrosilylation of preceramic polymers

We report new polysiloxane and polycarbosilane aerogels, which have been obtained by crosslinking Si–H-containing polymers with a CC-containing crosslinker via hydrosilylation reactions. The crosslinking reaction has been carried out in a highly diluted solution using up to 97 vol% of solvent. The obtained aerogels have a colloidal structure with meso- and macropores. Density as low as 0.17 g cm−3 has been reached, which implies a porosity of ca. 84 vol%

In vitro evaluation of granules obtained from 3D sphene scaffolds and bovine bone grafts: chemical and biological assays

Sphene is an innovative bone graft material. The aim of this study was to investigate and compare the physicochemical and biological properties of Bio-Oss® (BO) and in-lab synthesized and processed sphene granules. BO granules of 1000-2000 μm (BO-L), 250-1000 μm (BO-S) and 100-200 μm (BO-p) for derived granules, and corresponding groups of sphene granules obtained from 3D printed blocks (SB-L, SB-S, SB-p) and foams (SF-L, SF-S and SF-p) were investigated. The following analyses were conducted: morphological analysis, specific surface area and porosity, inductively coupled plasma mass spectrometry (ICP-MS), cytotoxicity assay, Alizarin staining, bone-related gene expression, osteoblast migration and proliferation assays. All pulverized granules exhibited a similar morphology and SF-S resembled natural bone. Sphene-derived granules showed absence of micro- and mesopores and a low specific surface area. ICP-MS revealed a tendency for absorption of Ca and P for all BO samples, while sphene granules demonstrated a release of Ca. No cellular cytotoxicity was detected and osteoblastic phenotype in primary cells was observed, with significantly increased values for SF-L, SF-S, BO-L and BO-p. Further investigations are needed before clinical use can be considered

Porphyrin-containing polyimide films deposited by high vacuum co-evaporation

Abstract Thin films of porphyrin-containing polyimide were produced by high vacuum co-evaporation of 4,4′-hexafluoroisopropylidene diphthalic anhydride (6FDA), 3,3′-diaminodiphenyl sulfone (DDS) and 5,10,15,20 meso-tetraphenyl porphyrin (TPP). The films were characterized by FT-IR analysis, optical absorption and emission spectroscopy. FT-IR analysis shows that the film matrix is comprised of only unreacted monomers. The conversion of monomers to polyamic acid and the following condensation to polyimide were studied by curing the samples at temperatures up to 240 °C. The amount of polyamic acid increases from room temperature to 120 °C, while at higher temperature it starts to condense to polyimide. Optical analysis shows that TPP is incorporated in the film matrix and its chemical state is determined by the interaction with the monomers, polyamic acid and polyimide. After curing the TPP molecules are finely dispersed in the polyimide matrix and their absorption and fluorescence properties are wholly preserved

Optical and Scintillation Properties of Polydimethyl-Diphenylsiloxane Based Organic Scintillators

Polysiloxane based scintillators with high light yield have been synthesized. The polymer consists in cross-linked polydimethyl-co-diphenylsiloxane with different molar percentages of phenyl units. 2,5-diphenyl oxazole (PPO) and 2,5-bis(5-ter-butyl-2-benzoxazolyl)thiophene (BBOT) have been dispersed in the polymer as dopants. The energy transfer and scintillation capabilities have been investigated, for two different amounts of phenyl groups in the polymer network and for different concentrations of dye molecules, by means of fluorescence spectroscopy, ion beam induced luminescence (IBIL) and scintillation yield measurements with ? particles from an 241Am source. The luminescence features and the scintillation yields have been correlated to the composition of the scintillators

Soluble phthalocyanines as optical gas sensing materials

A novel soluble phthalocyanine compound, i.e zinc phthalocyanine (sulfonamide) has been synthesized by chemical substitution of zinc phthalocyanine and used to produce thin solid films by means of the spin coating technique. The chemical structure of the spin coated films has been investigated by FT-IR analysis. Atomic Force Microscopy (AFM) has been used to characterize the film morphology and to measure the film thickness. The spin coated films have been tested as optical sensing materials of volatile organic compounds such as methanol, ethanol and 2-propanol. The change of optical reflectance of the films upon exposure to alcohol-vapour-containing atmospheres has been measured versus alcohol concentration and exposure time. The films exhibit a fast and reproducible response, with a complete and fast recovery in methanol and ethanol-containing atmospheres, while diffusion-driven effects appear during exposure to 2-propanol. The response and sensitivity of the films to ethanol vapour is higher than to methanol and 2-propanol

Novel Correlations between Spectroscopic and Morphological Properties of Activated Carbons from Waste Coffee Grounds

Massive quantities of spent coffee grounds (SCGs) are generated by users around the world. Different processes have been proposed for SCG valorization, including pyrolytic processes to achieve carbonaceous materials. Here, we report the preparation of activated carbons through pyrolytic processes carried out under different experimental conditions and in the presence of various porosity activators. Textural and chemical characterization of the obtained carbons have been achieved through Brunauer–Emmett–Teller (BET), ESEM, 13C solid state NMR, XPS, XRD, thermogravimetric and spectroscopic determinations. The aim of the paper is to relate these data to the preparation method, evaluating the correlation between the spectroscopic data and the physical and textural properties, also in comparison with the corresponding data obtained for three commercial activated carbons used in industrial adsorption processes. Some correlations have been observed between the Raman and XPS data

Siloxane-Based Nanocomposites Containing 6LiF Nanocrystals for Thermal Neutrons Detection

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New investigations on the 32S(3He,d)33Cl reaction at 9.6 MeV bombarding energy

The 32S(3He,d)33Cl one-proton transfer reaction is a powerful tool to investigate the spectroscopy of low-lying states in the proton-rich 33Cl nucleus. However, the extraction of firm differential cross-section data at various angles to benchmark and constrain theoretical models is made challenging by the presence of competitive reactions on target contaminants. In this paper we report on arecent measurement using a new generation hodoscope of silicon detectors, capable to detect and identify emitted deuterons down to energies of the order of 2 MeV. The high angular segmentation of our hodoscope combined with a suitable target to control possible contaminants, allowed to unambiguously disentangle the contribution of various states in 33Cl, in particular the 2.352 MeV state lying just few tens of keV above the proton separation energy