Combining Raman and infrared spectroscopy as a powerful tool for the structural elucidation of cyclodextrin-based polymeric hydrogels

A detailed experimental and theoretical vibrational analysis of hydrogels of b-cyclodextrin nanosponges (b-CDNS), obtained by polymerization of b-cyclodextrin (b-CD) with the cross-linking agent ethylenediaminetetraacetic acid (EDTA), is reported here. Thorough structural characterization is achieved by exploiting the complementary selection rules of FTIR-ATR and Raman spectroscopies and by supporting the spectral assignments by DFT calculations of the spectral profiles. The combined analysis of the FTIR-ATR spectra of the polymers hydrated with H2O and D2O allowed us to isolate the HOH bending of water molecules not involved in symmetrical, tetrahedral environments. The analysis of the HOH bending mode was carried out as a function of temperature, showing the existence of a supercooled state of the water molecules. The highest level of cooperativity of the hydrogen bond scheme was reached at a value of the b-CD/EDTA molar ratio n = 6. Finally, the connectivity pattern of ‘‘uncoupled’’ water molecules bound to the nanosponge backbone was found to be weakened by increasing T. The temperature above which the population of non-tetracoordinated water molecules becomes predominant turned out to be independent of the parameter n

Spectroscopy 16 (2002) 245-250 245 IOS Press Recent results on biomedical problems: A Fourier transform infrared (FT-IR) study

Abstract. In the present work, we report on a vibrational study performed on rat encephalon samples and on human tissue affected by cancer, using Fourier Transform Infrared absorbance spectroscopy. As the brain rat tissue is concerned, the FT-IR measurements, performed in the CH-OH vibrational stretching region (2400-3800 cm −1 ), permitted us to reveal the presence of a very diffuse commercial benzodiazepine: VALIUM R . The comparison between the spectral features of normal brain and the ones of samples with administrated substance has unambiguously showed that the CH stretching region seems not to be affected by any change for the pharmacological treatment, instead the OH band is strongly modified probably due to the presence of a new spectral contribution characteristic of diazepam molecule. In the case of skin tissue the investigation was addressed to characterize the presence of two different pathologies, namely epithelioma and basalioma, and to show clear different spectral features passing from the normal tissue to the malignant one in particular in the region (1500-2000 cm −1 ) which is typical of the lipids vibrational bands

What is the crisis of Western sciences?

© 2016, Springer Science+Business Media Dordrecht. This article is an attempt to formulate a clear definition of the concept of crisis of Western sciences introduced by Husserl in his last work. The attempt will be based on a reading of the Krisis, which will stress its underlying continuity with Husserl’s life-long concerns about the theoretical insufficiency of positive sciences, and downplay the novelty of the idea of crisis itself within Husserl’s work. After insisting on the fact that, according to Husserl, only an account of the shortcomings of the scientificity of Western sciences can justify the claim that they are undergoing a crisis, it will be argued that the common definition of the crisis of the sciences as the loss of their significance for life rests on a misunderstanding. The crisis of Western sciences will be characterized, instead, as the repercussion of the crisis of the scientificity of philosophy (and, specifically, of metaphysics) on the scientificity of positive sciences. The loss of significance of scientific knowledge for our existence will in turn appear as a further, inevitable consequence of the uprooting of the sciences from the soil of a universal philosophy culminating in metaphysics, and thus, as a phenomenon deeply intertwined with the crisis of Western sciences, but not identical to it

New insights to assess the consolidation of stone materials used in built heritage: the case study of ancient graffiti (Tituli Picti) in the archaeological site of Pompeii

Tituli Picti are an ancient form of urban graffiti very common in the archaeological site of Pompeii (Naples, South—Italy). They are generally made of red pigments applied on walls of Campanian ignimbrite. This paper deals with a scientific investigation aimed to their conservation. This is a challenging task since it requires a multidisciplinary approach that includes restorers, archaeologists and conservation scientists. The study has provided suggestions on the proper way to conserve Tituli Picti over time. In the present work, several specimens of Campanian ignimbrite were painted with red earth pigment; lime and Arabic gum have been used as binders as well. Such painted stones were treated with three consolidants: a suspension of reactive nanoparticles of silica, ethyl silicate and an acrylic microemulsion. Treated and untreated specimens were subjected to thermal aging, artificial solar radiation and induced crystallization decay. It has been assessed the colorimetric variations induced by treatments. Moreover, the micromorphologic features of the consolidated surfaces have been highlighted by means of electron microscope observations. The scotch tape test allowed to compare the superficial cohesion induced by the three used products. According to the results, ethyl silicate seems to represent the most successful product

RBS, PIXE, Ion-Microbeam and SR-FTIR Analyses of Pottery Fragments from Azerbaijan

The present work is aimed at the investigation of the ceramic bulk and pigmented glazed surfaces of ancient potteries dating back to XIX century A.D. and coming from the charming archeological site located in the Medieval Agsu town (Azerbaijan), a geographic area of special interest due to the ancient commercial routes between China, Asia Minor, and Europe. For the purpose of the study, complementary investigation tools have been exploited: non-destructive or micro-destructive investigation at elemental level by ion beam analysis (IBA) techniques, by using Rutherford Backscattering Spectrometry (RBS), Proton-Induced X-ray Emission (PIXE) spectroscopy and ion-microbeam analysis, and chemical characterization at microscopic level, by means of synchrotron radiation (SR) Fourier transform infrared (FTIR) microspectroscopy. The acquired information reveals useful for the identification of the provenance, the reconstruction of the firing technology, and finally, the identification of the pigment was used as a colorant of the glaze

Vibrational density of states and elastic properties of cross-linked polymers: combining inelastic light and neutron scattering

The vibrational dynamics of a new class of cross-linked polymers made up of cyclodextrins is here investigated in the microscopic range by the joint use of light and inelastic neutron scattering experiments. The effect of increasing the connectivity of the polymeric network on the vibrational dynamics of the system is studied by exploiting the complementarity of these two different probes. The derived densities of vibrational states of the polymers evidence the presence of the characteristic anomalous excess of vibrational modes with respect to the Debye level, already observed in the low-frequency Raman spectra and referred to as boson peak (BP). The overall analysis of the spectra suggests an emerging picture in which the motions of hydrogen atoms of the polymers are progressively hampered when the cross-linking degree of the covalent network increases. At the same time, the frequency and intensity of the BP are found to significantly change by increasing the cross-linking degree of the polymeric network, as clearly suggested by the existence of a scaling-law for the BP evolution. These findings support the conclusion that the growing of the covalent connectivity of the system induces a general modifications of the elastic properties of these cyclodextrin-based polymers, which are, once again, modulated by the cross-linking agent/cyclodextrin molar ratio

Synthesis and characterization of a hyper-branched water-soluble β-cyclodextrin polymer

A new hyper-branched water-soluble polymer was synthesized by reacting β-cyclodextrin with pyromellitic dianhydride beyond the critical conditions that allow the phenomenon of gelation to occur. The molar ratio between the monomers is a crucial parameter that rules the gelation process. Nevertheless, the concentration of monomers in the solvent phase plays a key role as well. Hyperbranched β-cyclodextrin-based polymers were obtained performing the syntheses with excess of solvent and cross-linking agent, and the conditions for critical dilution were determined experimentally. A hyper-branched polymer with very high water solubility was obtained and fully characterized both as for its chemical structure and for its capability to encapsulate substances. Fluorescein was used as probe molecule to test the complexation properties of the new material

Relationship between Elastic Properties and Gel-to-Sol Transition in Cyclodextrin-Based Hydrogel

In order to elucidate the effects of the nature of the cross-linker, of the hydration level and of the hydrophobic/hydrophilic balance on the macro- and microscopic properties of a paradigmatic model of polysaccharide hydrogel, an integrated approach based on the combined use of low-frequency Raman scattering and FTIR-ATR absorption has been developed. The proposed methodology aims to explore the stability range of the liquid and gel phase diagram of the system. This approach was applied to cyclodextrin based nanosponges (CDNS), prepared by polymerization of \u3b1-, \u3b2-, and \u3b3-cylcodextrins (CDNS) with an activated derivative of ethylenediamine tetra acetic acid. It revealed successful, on one side, for a comparative analysis of the elasticity, as mesoscopic parameter, of the dry polymeric network, measured by Raman spectroscopy in the low frequency (0 \uf7 150 cm\u20131) range, and, on the other side, for the investigation of the water holding capacity, as macroscopic parameter, through the analysis of the vibrational dynamics of water molecules in the swollen polymers, monitored by FTIR-ATR spectroscopy in two selected wavenumber regions, i.e. 2800 \uf7 3800 cm\u20131 and 1500 \uf7 1800 cm\u20131, where the O-H stretching and H-O-H bending vibrations respectively occur. As main result, the same evolution as a function of the molar ratio n, has been observed for the elasticity on mesoscopic scale, as described by the Boson Peak (\u3c9BP) and the swelling ability on macroscopic scale, expressed by the mass ratio m describing the gel-to-sol transition in these systems. From the results, the way for a rational development of stimuli-responsive systems with specifi performances, by modulating the stability range of the liquid suspension and gel phases properly changing the molar ratio n during the synthesis, is opened

Isolation of NDM-1-producing Pseudomonas aeruginosa sequence type ST235 from a stem cell transplant patient in Italy, May 2013

We describe the first isolation of an NDM-1-producing Pseudomonas aeruginosa in Italy. In May 2013, a patient with acute lymphoblastic leukaemia and history of prior hospitalisation in Belgrad, Serbia, underwent stem cell transplantation at a tertiary care hospital in Rome, Italy. After transplantion, sepsis by NDM-1-producing P. aeruginosa occurred, leading to septic shock and fatal outcome