Pyrolysis-GC/MS for the identification of macromolecular components in historical recipes.

Analytical pyrolysis with thermally assisted hydrolysis and methylation was employed to investigate ancient ointments collected from Spanish vessels coming from the sixteenth century pharmacies. The ointments were reproduced on the basis of historical recipes and characterization was made in comparison with real samples. Characteristic markers indicate the presence of beeswax, of animal and plant lipids, and of natural resins.

μ-EXAFS, μ-XRF, and μ-PL characterization of a multi-quantum-well electroabsorption modulated laser realized via selective area growth.

In the past few years, strong efforts have been devoted to improving the frequency of optical-fiber communications. In particular, the use of a special kind of integrated optoelectronic device called an electroabsorption modulated laser (EML) allows communication at 10 Gb s(-1) or higher over long propagation spans (up to 80 km). Such devices are realized using the selective area growth (SAG) technique and are based on a multiple quantum well (MQW) distributed-feedback laser (DFB) monolithically integrated with a MQW electroabsorption modulator (EAM).

Mid-IR fiber-optic reflectance spectroscopy for identifying the finish on wooden furniture.

Mid-IR fiber-optic reflectance spectroscopy (FORS) is a totally noninvasive infrared analytical technique allowing the investigation of artworks without the need for any sampling. The development and optimization of this analytical methodology can provide a tool that is capable of supporting conservators during the first steps of their interventions, yielding fast results and dramatically reducing the number of samples needed to identify the materials involved. Furthermore, since reflection IR spectra suffer from important spectral anomalies that complicate accurate spectral interpretation, it is important to characterize known reference materials and substrates in advance.

The iron-related molecular toxicity mechanism of synthetic asbestos nanofibres: a model study for high-aspect-ratio nanoparticles.

Asbestos shares with carbon nanotubes some morphological and physico-chemical features. An asbestos-like behaviour has been recently reported by some authors, though the mechanism of toxicity may be very different. To identify at the atomic level the source of toxicity in asbestos, the effect of progressive iron loading on a synthetic iron-free model nanofibre previously found non-toxic in cellular tests was studied.

Structural and spectroscopic investigation of ZnS nanoparticles grown in quaternary reverse micelles.

ZnS nanoparticles were synthesized in four component "water in oil" microemulsions formed by a cationic surfactant (cetyltrimethylammonium bromide, CTAB), a cosurfactant (pentanol or butanol), n-hexane and water. The effect of various parameters (nature of cosurfactant, water/surfactant W(0), and alcohol/surfactant P(0)) on the formation and stability of ZnS nanoparticles was investigated thoroughly. UV-Vis spectroscopy was employed to directly follow the formation of ZnS systems in the microemulsions.

Vitamin E-stabilized UHMWPE for total joint implants: a review.

Background: Osteolysis due to wear of UHMWPE limits the longevity of joint arthroplasty. Oxidative degradation of UHMWPE gamma-sterilized in air increases its wear while decreasing mechanical strength. Vitamin E stabilization of UHMWPE was proposed to improve oxidation resistance while maintaining wear resistance and fatigue strength.

Affinity of hydroxyapatite (001) and (010) surfaces to formic and alendronic acids: a quantum-mechanical and infrared study.

The affinity of the (001) and of the water reacted (010)WR hydroxyapatite surfaces towards formic and alendronic acids is studied with density functional theory (PBE functional) using periodic boundary conditions based on Gaussian basis set. Structures, energetic of the adsorption and vibrational features of the adsorbates are computed in order to understand at the atomic level both the cariogenic processes (for the formic acid) and the features of anti-osteoporosis drugs (for the alendronic acid). For both molecules the interaction energy is very high on an absolute scale, and for all examined cases, it is higher on the (010)WR HA surface than on the (001) one.

Probing the surfaces of heterogeneous catalysts by in situ IR spectroscopy.

This critical review describes the reactivity of heterogeneous catalysts from the point of view of four simple, but essential for Chemistry, molecules (namely dihydrogen, carbon monoxide, nitrogen monoxide and ethylene) that are considered as probes or as reactants in combination with "in situ" controlled temperature and pressure Infrared spectroscopy. The fundamental properties of H(2), CO, NO and C(2)H(4) are shortly described in order to justify their different behaviour in respect of isolated sites in different environments, extended surfaces, clusters, crystalline or amorphous materials. The description is given by considering some "key studies" and trying to evidence similarities and differences among surfaces and probes (572 references).

X-ray absorption spectroscopies: useful tools to understand metallorganic frameworks structure and reactivity.

The large unit cells, the enormous flexibility and variation in structural motifs of MOFs represent a big challenge in the characterization of MOF materials, particularly in cases where single crystal diffraction data are not available. In this critical review it is shown that in cases where only powder diffraction data are available additional structural information, particularly regarding local coordination within the inorganic cluster, are often mandatory in order to solve the structure. There are also cases where the inorganic cluster does not follow the symmetry of the overall structure.

Gas-phase phenol methylation over Mg/Me/O (Me = Al, Cr, Fe) catalysts: mechanistic implications due to different acid-base and dehydrogenating properties.

This contribution reports about an in situ FT-IR investigation and the catalytic reactivity of Mg/Me(3+) mixed oxides (Me = Cr, Fe, or Al; Mg/Me = 2, atomic ratio) in the gas-phase methylation of phenol with methanol. It is the second of two papers concerning the mentioned systems, and its purpose is twofold: to confute the classic and not accurate theory concerning the reaction mechanism, and to propose a novel interpretation based on the combined use of catalytic tests and in situ molecular spectroscopy. Results here reported highlight that: (i) the reaction mechanism in phenol methylation, when catalysed by basic systems, is not a classical electrophylic substitution, as generally reported in the literature, but proceeds through the formation of formaldehyde as an intermediate, and (ii) the catalytic behaviour in respect to both methanol and phenol reactants is strictly dependent on catalyst features.

Spectroscopic CW-EPR and HYSCORE investigations of Cu(2+) and O(2)(-) species in copper doped nanoporous calcium aluminate (12CaO.7Al(2)O(3)).

Continuous wave (CW) and pulse electron paramagnetic resonance in a variant of hyperfine sublevel correlation spectroscopy (HYSCORE) were used for obtaining structural information concerning speciation and local environment of alien Cu(2+) and native O(2)(-) ions encaged in copper doped nanoporous 12CaO.7Al(2)O(3) (mayenite). The samples were prepared by a solid-state reaction and characterized by means of XRD, SEM, and Raman techniques.

Nanocrystalline diamond microelectrode arrays fabricated on sapphire technology for high-time resolution of quantal catecholamine secretion from chromaffin cells.

The quantal release of oxidizable molecules can be successfully monitored by means of polarized carbon fiber microelectrodes (CFEs) positioned in close proximity to the cell membrane. To partially overcome certain CFE limitations, mainly related to their low spatial resolution and lack of optical transparency, we developed a planar boron-doped nanocrystalline diamond (NCD) prototype, grown on a transparent sapphire wafer. Responsiveness to applied catecholamines as well as the electrochemical and optical properties of the NCD-based device were first characterized by cyclic voltammetry and optical transmittance measurements.

Synergistic behavior of bimetallic rhenium cluster catalysts: spectroscopic investigation into the nature of the active site.

Single-site Re nanoparticles were produced by anchoring dirhenium organometallic clusters on to the inner walls of mesoporous silica. The presence of oxophilic atoms (Sb or Bi) is essential to obtain well dispersed Re(0) centers. The interaction between the organometallic cluster and the silica support is critical for the generation of well-defined and isolated Re(0) single sites.

Hydroxyapatite as a key biomaterial: quantum-mechanical simulation of its surfaces in interaction with biomolecules.

Hydroxyapatite is the mineral component of human bones and teeth enamel and is used as synthetic biomaterial. It also grows outside bioglasses as a response of their incorporation in body fluids. The focus is then on understanding the microscopic steps occurring at its surfaces as this allows researchers to understand the key features of biomolecular adhesion.

Role of dispersive interactions in the CO adsorption on MgO(001): periodic B3LYP calculations augmented with an empirical dispersion term.

Empirically dispersion corrected B3LYP method (i.e. B3LYP-D) is demonstrated to give excellent results for structure, adsorption energy and vibrational frequency shift for the CO molecule adsorbed on the MgO(001) surface, a system considered a challenge for current density functional methods.

Preparation of supported Pd catalysts: from the Pd precursor solution to the deposited Pd2+ phase.

The preparation by the deposition-precipitation method (using Na(2)PdCl(4) as a palladium precursor and Na(2)CO(3) as a basic agent) of Pd catalysts supported on gamma-Al(2)O(3) and on two different types of active carbons has been followed by several techniques (UV-vis, EXAFS, XRPD, and TPR). This work consists of four successive parts: the investigation of (i) the palladium precursor liquid solution (in the absence of substrate), (ii) the solid precipitated phase (in the absence of substrate), (iii) the precipitated Pd(2+)-phase on the supports as a function of Pd loading from 0.5 to 5.

Deep-space glycine formation via Strecker-type reactions activated by ice water dust mantles. A computational approach.

A Strecker-type synthesis of glycine by reacting NH(3), H(2)C=O and HCN in presence of ice water (H(2)O-ice) as a catalyst has been theoretically studied at B3LYP/6-31+G(d,p) level within a cluster approach in order to mimic reactions occurring in the interstellar and circumstellar medium (ICM). Results indicate that, despite the exoergonic character of the considered reactions occurring at the H(2)O-ice surface, the kinetics are slow due to relatively high electronic energy barriers (ΔU(0)(≠)=15-45 kcal mol(-1)). Reactions occurring within H(2)O-ice cavities, in which ice bulk effects have been modeled by assuming a dielectric continuum (ε=78), show energy barriers low enough to allow NH(2)CH(2)OH formation but not NH=CH2 (ΔU(0)(≠)= 2 and 21 kcal mol(-1), respectively) thus hindering the NH(2)CH(2)CN formation, i.

Photoactive hybrid nanomaterials: indocyanine immobilized in mesoporous MCM-41 for "in-cell" bioimaging.

Mesoporous silica nanoparticles are being explored as versatile tools for various biomedical and biotechnological applications including disease diagnosis, drug delivery, and intracellular imaging. In this paper, the synthesis and characterization of a fluorescent hybrid mesoporous silica nanomaterial, which is noncytotoxic and shows great potential for "in-cell" bioimaging applications, will be described. The hybrid mesoporous material has been obtained by confining highly fluorescent organic dyes, belonging to the indocyanine family, within the channels of mesoporous MCM-41.

On the compatibility criteria for protein encapsulation inside mesoporous materials.

The properties of the enzyme pepsin, relevant to its incorporation inside the channels of mesoporous silica materials in the preparation of bioinorganic hybrids, are highlighted by molecular dynamics simulations of aqueous solutions of the protein under conditions optimal for encapsulation in SBA-15. The protein size, shape, flexibility and surface properties are calculated with the aim of deriving general accessibility/compatibility criteria favouring encapsulation inside mesoporous systems.

Differential repression by the transcription factor REST/NRSF of the various Ca2+ signalling mechanisms in pheochromocytoma PC12 cells.

Expression of the nerve cell phenotype is orchestrated by the REST/NRSF transcription repressor, working on hundreds of genes recognized at a specific regulatory binding sequence. Most PC12 clones, the most frequently employed neuronal model, maintain low levels of REST; however a few, defective of neurosecretion, express high levels. To investigate the role of REST in Ca2+ signalling we studied the [Ca2+](i) changes in single cells of four clones, two wild-type and two defective, pre-treated for 5 days with NGF.

Direct evidence of adsorption induced Cr(II) mobility on the SiO(2) surface upon complexation by CO.

In situ, temperature dependent, XAFS proved that Cr(II) grafted on SiO(2) is extracted from the surface upon CO adsorption at 100 K: DeltaR(Cr-O) = +0.08 A. CO adsorption evolves into two coverage dependent steps: (i) displacement of weak siloxane ligands (non-classical carbonyls); (ii) relaxation of R(Cr-O) surface bond, R(Cr-CO) optimization and transformation into classical carbonyls.

Advances in identification of plant gums in cultural heritage by thermally assisted hydrolysis and methylation.

Plant gums are present in works of art as binding media for watercolours and adhesives for cellulosic substrates. Thermally assisted hydrolysis and methylation (THM) in combination with analytical pyrolysis coupled to GC/MS has been applied to the characterisation of plant gums typically used in artworks. THM products from standard samples of arabic gum, tragacanth gum and cherry gum were characterised.

Fate of antibacterial spiramycin in river waters.

Spiramycin, a widely used veterinary macrolide antibiotic, was found at traceable levels (nanograms per litre range) in Po River water (N-Italy). The aqueous environmental fate of this antibiotic compound was studied through drug decomposition, the identification of the main and secondary transformation products (TPs), assessment of mineralisation and the investigation of drug TPs toxicity. Initially, laboratory experiments were performed, with the aim of stimulating the antibacterial transformation processes followed in aquatic systems.

Calculation of the dielectric constant epsilon and first nonlinear susceptibility chi((2)) of crystalline potassium dihydrogen phosphate by the coupled perturbed Hartree-Fock and coupled perturbed Kohn-Sham schemes as implemented in the CRYSTAL code.

The high-frequency dielectric varepsilon and the first nonlinear electric susceptibility chi((2)) tensors of crystalline potassium dihydrogen phosphate (KH(2)PO(4)) are calculated by using the coupled perturbed Hartree-Fock and Kohn-Sham methods as implemented in the CRYSTAL code. The effect of basis sets of increasing size on varepsilon and chi((2)) is explored. Five different levels of theory, namely, local-density approximation, generalized gradient approximation (PBE), hybrids (B3LYP and PBE0), and HF are compared using the experimental and theoretical structures corresponding not only to the tetragonal geometry I4d2 at room temperature but also to the orthorhombic phase Fdd2 at low temperature.