Search results for "CP-MAS NMR"

The Acqualadrone Rostrum: a physical-chemical investigation to understand the Material History

2013

The aim of this work is to define the conservation state and to ascertain the provenance of raw materials used in the construction of the Acqualadrone Rostrum. In 2008 the rostrum (an offensive naval weapon mounted on the prow at the waterline), from an ancient warship was recovered from the Mediterranean near Acqualadrone, Messina, Sicily. The archaeological discovery has led to the need for scientific research in order to plan the conservation treatment of this artefact. The discovery is exceptional because of the presence of a wooden section from the original ship. The physical-chemical investigation, by using some complementary spectroscopic techniques, was focused on the characterizati…

Solid state nmr characterization of the waterlogged wooden part of Acqualadrone roman rostrum

2014

The roman rostrum found in the sea of Acqualadrone (ME) was characterized in our previous papers. In the present work solid state NMR spectroscopy was applied on a wooden sample of the same artefact collected by coring and divided in four parts in order to correlate the conservation state to the depth. Results were compared with those obtained for a modern wood of the same species. A structural study was performed by the acquisition of 13C Cross Polarization Magic Angle Spinning (13C CP MAS NMR) spectra. These spectra were acquired to assign the chemical shifts of the species that are present in the wooden matrix. In addition the spectra analysis allowed us to determine the cellulose crysta…

Physicochemical Characterization Of Ancient Paper And Parchment With Solid State Nuclear Magnetic Resonance

2014

Historical paper and parchment are widely investigated in order to comprehend mechanisms of degradation and to plan proper conservation interventions. NMR spectroscopy is a powerful tool that allows to the changes occurring during the degradation process and to get information on the state of conservation. In this work a Cross Polarization Magic Angle Spinning Nuclear Magnetic Resonance (13C{1H} CP MAS NMR) study of a 16th century book is reported. The physicochemical characterization of paper samples collected from the book was performed through the evaluation of intensity and the changes in line width of signals in the spectra. 13C{1H} CP MAS NMR spectra of paper samples collected from th…

Synthesis, Characterization and Catalytic Activity of mesoporous Mn-MCM-41 materials

2011

MCM-41 has been synthesized at two different pH using cetyl-trimethylammonium bromide (CTAB) surfactant as template and adding the silica precursor to aqueous solutions containing CTAB. The obtained solids were calcined at 600 ◦C for 4 h. Mn-MCM-41 powders with different Mn/Si molar ratios were prepared using the incipient wetness method, followed by calcination at 550 ◦C for 5 h. At the end of the impregnation process the powders colour changed from white to brown whose intensity depends on manganese quantity. The materials characterization was performed by X-ray diffraction, N2 adsorption, 29Si Cross Polarization–Magic Angle Spinning NMR, and X-ray Photoelectron Spectroscopy. The effects …

Chemical and spectroscopic characteristics of the wood of Vitis vinifera cv. Sangiovese affected by esca disease.

2009

Chemical and spectroscopic analyses ((13)C cross-polarization-magic angle spinning NMR and attenuated total reflection Fourier transform infrared spectroscopies) were carried out on the wood of Vitis vinifera cv. Sangiovese with brown-red discoloration and black streaks caused by esca disease. The analyses of the brown-red wood revealed the destruction of hemicelluloses and noncrystalline cellulose as well as modifications in the pectic and ligninic wood fractions. The pectic fraction consisted of carbohydrates associated with polyphenols. The lignin fraction exhibited only a few changes in the aromatic systems and a partial demethylation, and it appeared to be associated with condensed phe…

Pt(II) complex @mesoporous silica: preparation, characterization and study of release

2016

Cisplatin analogs, having cytotoxic activity higher than that exerted by cisplatin, have recently triggered considerable interest by the community. The cis-[PtCl2(DMSO)HL]·2DMSO, where HL = 7-amino-2-(methylthio)[1,2,4]triazolo[1,5-a]pyrimidine-6-carboxylic acid, has shown a potent cytotoxic activity on HepG2 hepatocarcinoma cells, while under identical conditions, it did not affect normal immortalized human liver cells (Chang). In this work, the above complex has been incorporated into MCM41 mesoporous silica, pure and functionalized with amino group, which is considered one of the best host for a drug delivery system for carrying high dosages of a variety of drugs in their mesopores. Sinc…

Ce:Y3Al5O12−Poly(methyl methacrylate) Composite for White-Light-Emitting Diodes

2014

A Ce:YAG-poly(methyl methacrylate) (PMMA) composite was prepared by using the melt compounding method. The structure and morphology were investigated by X-ray diffractometry, transmission electron microscopy, and small-angle X-ray scattering. The optical properties (emission, excitation, and fluorescence decay rate) of the composite were studied by using photoluminescence spectroscopy. The polymer–filler interactions were studied using 13C cross-polarization magic-angle spinning NMR spectroscopy (13C{1H} CP-MAS NMR). The results indicated that Ce:YAG particles are well-dispersed in the PMMA matrix without loss of their luminescence properties or significant spectral shift, thus suggesting t…

Corrigendum to “The effect of silica nanoparticles on the morphology, mechanical properties and thermal degradation kinetics of PMMA [Pol. Degrad. St…

2012

The effect of silica nanoparticles on the morphology, mechanical properties and thermal degradation kinetics of PMMA

2012

Abstract Silica–PMMA nanocomposites with different silica quantities were prepared by a melt compounding method. The effect of silica amount, in the range 1–5 wt.%, on the morphology, mechanical properties and thermal degradation kinetics of PMMA was investigated by means of transmission electron microscopy (TEM), X-ray diffractometry (XRD), dynamic mechanical analysis (DMA), thermogravimetric analyses (TGA), Fourier-transform infrared spectroscopy (FTIR), 13 C cross-polarization magic-angle spinning nuclear magnetic resonance spectroscopy ( 13 C{ 1 H} CP-MAS NMR) and measures of proton spin-lattice relaxation time in the rotating frame ( T 1 ρ ( H )), in the laboratory frame ( T 1 ( H )) a…

Incorporation of Pt(II) complex with [amino-2(methylthio)(1,2,4)triazole-(1,5-a)pyrimidine-6-carboxylic-acid] ligand in MCM41 for controlled release

2015

Drug carriers play a critical role for the loading and the release of the drug. A promising frontier is represented by a new class of innovative medicines that represents directional transport vehicles "drug delivery" and consist of assembled structures carrier (nano)-drug. Silica-based materials, nontoxic, biocompatible, have been used as adjuvant and excipient in pharmaceutical technology. In this class of compounds, the mesoporous materials, such as MCM41, SBA-15 and hexagonal mesoporous silica, have been investigated for medication and drug delivery due to their properties. In fact, these materials show a large specific pore volume made up of regular pores having a diameter in the nanom…