Individuation of characteristic parameters of “glass paste” of Meridional Etruria by the use of scientific methodologies

The individuation of parameters that characterize decorations in “glass paste” of Etruscan jewels in Meridional Etruria area, by the use of scientific methodologies, has the aim to collocate this typology of manufacts in a historical and geographical context and to improve the knowledge of the technology connected with their realization. The term “glass paste” is widely used in humanistic literature to describe different materials, all based on a “glass like” composition, but its definition is lacking or confusing if the term is not referred to a scientific meaning.The glass analysis is difficult owing to the complexity of the elements that compose the various classes of vitreous materials. For this reason the interpretation of the composition table containing the values of the numerous glass elements, induces the use of statistical methods for the elaboration of the results. The multivariate analysis can be a valid tool for an immediate lecture of the common characteristics of the different typologies of vitreous materials.In this work, the application of the Principal Component Analysis (PCA), has been applied for the elaboration of chemical composition data obtained by electronic microanalysis (SEM-EDS) on findings coming from Etruscan archaeological sites of Nepi and Cerveteri, and on pearls of a necklace from Castellani's Collection. Besides, an attempt has been made to compare the chemical elements found in the vitreous materials of the jewelry with the elements of sands from probable sites along the rivers present in the Etruscan sites by following the indications reported by historical fonts.The obtained results furnished information in various directions, either for the characterization of each historical sample analyzed or the validation of the applied statistical methodology for the composition data elaboration, besides it has been possible to contribute in the knowledge of the possible existence of glass production sites in the Meridional Etruria, more specifically for the realization of decoration in glass paste.     

Conventional and unconventional infrared spectrometry and their quantitative interpretation

In condensed matter, optical properties can be described by a dielectric function (DF), and the structures observed in spectra are then related to the poles and zeros of the DF. As an example, model functions are calculated by a fit to measured spectroscopic data for polystyrene and silica. The first material shows weak, narrow bands and the latter strong, broad bands and a negative real part of the DF.Based on these model DFs, spectra are simulated which are expected to be obtained by “conventional” methods such as transmittance or reflectance measurements, or by “unconventional” methods such as reflectance at oblique incidence, diffuse reflectance, photoacoustic spectroscopy and attenuated total reflectance. A variety of simulated, typical spectra are plotted as a small “atlas”. Conditions are discussed that allow a straightforward procedure for interpreting the spectra quantitatively, i.e., the evaluation of the resonance frequency and the concentration of the oscillators under consideration.It is shown that for systems characterized by weak, narrow oscillator lines, mostly an intuitive interpretation is possible, looking only at the position and strength of “lines” in the spectra. Materials showing strong polar vibrations, however, require more sophisticated procedures for interpreting the spectra.     

Pigment identification on “Pietà” of Barletta, example of Renaissance Apulian sculpture: A Raman microscopy study

A study of the original painting layer of the “Pietà” of Barletta, a polychrome statue, important example of Renaissance Apulian sculpture, was performed by μ-Raman spectroscopy. Vermilion was identified in the original layer of the blood drops on Jesus knee. Lazurite was identified as the original blue pigment on Our Lady's veil and lace, currently a yellow ochre-like color. The use of lazurite demonstrates the historical-artistic importance of this polychrome statue, and supports the hypothesis that this artwork was probably commissioned by Our Lady's devotees to itinerant artists inspired by the more precious Vesperbilder model.     

Application of receptor models to airborne particulate matter

The human activities in their various aspects cause a change in the natural air quality. This change results more marked in very populated and in high industrialized areas. Some pollutants emitted are typical of a particular activity. Each source of pollution is identified by its profile in the composition of the emissions in the environment. Multivariate receptor models can be used in order to apportion pollutants to the different sources assessing the contribution of each source to the total pollution.This paper deals with the application of Absolute Principal Component Scores (APCS) receptor model to data obtained from the automatic network of air quality monitoring in the city of Bari (South Italy). The parameters monitored by automatic networks, as bihourly values, are PM₁₀, NO_x, CO, Benzene, Toluene, Xilene. The data shown in this paper concerning 1 month almost of sampling in different monitoring stations of Bari Municipality during the period of time from January 2005 to April 2006. Moreover preliminary results obtained applying the APCS model to daily PM_2.5 samples collected during SITECOS PRIN project are shown. The results concerning data collected in corso Cavour (Bari) during the month of October 2005.The results obtained by APCS receptor model seem to suggest a poor contribution of the “vehicular traffic source” and a relevant contribution of the “secondary particulate source” to particulate matter concentrations.     

Nucleation and growtn of polythiophene films on gold electrodes

The nucleation and growth of polythiophene films on gold electrodes has been studied using potentiostatic steps. The mechanism has been deduced and estimates made of the kinetic parameters. Dissolution of the gold substrate at potentials where thiophene polymerisation occurs is suppressed by the initial rapid formation of a monolayer of polymer. The data indicate that formation of bulk film occurs by the instantaneous nucleation and three-dimensional growth of polymer on top of this monolayer. Rate constants for growth parallel to the surface on the bare gold substrate and the covering polymer layer are surprisingly very similar. Growth perpendicular to the surface is slightly more rapid, typically by a factor of 1.5–3, although it is less dependent on potential. The high density of nuclei results in their overlap at an early stage, after which growth is only possible perpendicular to the surface. Within a narrow potential range, the observation of maxima and minima in current-time transients is interpreted in terms of the “death” and “rebirth” of growing centres.     

Diffuse reflectance spectroscopy of powders

Diffuse reflectance (DRIFT) spectra in the mid-IR region, especially of inorganic powders, often reveal inverted or derivative-like structures (“reststrahlen” bands) which make their straightforward interpretation in terms of the Kubelka-Munk theory difficult. A simulation technique based on a combination of single scattering (Mie theory) and radiative transfer (with Kubelka-Munk as a special case) is reported that allows measured DRIFT spectra to be described without use of any free “fit” parameters. The results for silica glass microspheres and silicon carbide powder show that not specular reflectance but prominent structures in the single particle scattering cross-section are responsible for the reststrahlen features which cannot be suppressed even by diluting the powder in an excess of KBr. The efficiency of a “blocker” device in DRIFTS is also discussed.     

Amine groups functionalized gel-type resin supported Pd catalysts: Physicochemical and catalytic properties in hydrogenation of alkynes

Palladium catalysts (0.125–0.5 wt.% Pd) supported by amine groups—functionalized gel-type resin (FCN) were studied in the hydrogenation of alkynes reagents, 2-butyne-1,4-diol and phenylacetylene. The catalysts were prepared by two routes. The first, “OAc” is based on the immobilization of Pd-precursor in the pre-swollen resin from THF solution of Pd(OAc)₂, followed by chemical reduction of the Pd-centers. This method produces Pd particles of size in nano-scale. The second procedure, “aq” implies the deposition of Pd-species on dry resin beads using aqueous solution of PdCl₂. Reduction of these Pd-species gives relatively large Pd particles, dominating are 30–50 nm in size. The SEM studies performed over the cross-section of catalysts grains showed location of Pd in outer shell of polymer beads in both “OAc” and “aq” catalysts; however, thinner layer of Pd appears in “aq” series catalysts. In the presence of all catalysts, prepared by “OAc” and “aq” methods the selectivity towards alkenes is high, above 90%. The catalysts of “aq’ series are much more active and more selective than “OAc” analogues giving selectivity to alkene ca. 94% at almost complete conversion of alkynes. Moreover, catalytic performance of “aq’ series catalyst is unchanged under recycling use. The catalyst was recovered and reused 4 times, maintaining its catalytic efficiency.     

Supramolecular edifices and switches based on metals

Our studies allowed to unravel at least partially, the “so-called” spontaneous self-assembly processes of supramolecular edifices based on metals. The formation of a tricuprous double-stranded helix in solution was found to be driven by thermodynamics via highly distorted intermediates. Dinuclear europium(III) triple-stranded helices were built in solution via alternative “braiding” and “keystone” mechanism. The overall process was also dominated by thermodynamics. Moreover, multipodal ligand with the appropriate binding sites can operate as Cu(II)/Cu(I) molecular switches. Recently, we examined ligands with neighboring binding functionalities (N,N) and (N,O) which confer to the corresponding divalent metal complexes new properties. They could operate as proton-driven multistage molecular switching devices based on region-selective metal binding.     

Preparation and catalytic activity of titanium silicalite-1 zeolite membrane with TPABr as template

The preparation of the supported titanium silicalite-1 (TS-1) zeolite membrane with inexpensive tetrapropylammonium bromide (TPABr)/weak base synthesis system was studied by three methods, and the catalytic activity of the obtained TS-1 zeolite membrane was evaluated with the oxidation of 2-propanol (IPA) under pervaporation condition. It was found that TS-1 zeolite membrane could be successfully prepared with “seeding” or “seeding in situ” method, but could not be achieved with “in situ” method. Adding a little amount of promoter ions of PO₄³⁻ into the synthesis gel was of benefit to the catalytic activity of the prepared TS-1 zeolite membrane, but had no obvious effect on the membrane layer formation on the mullite porous support. For “seeding” method, the membrane prepared with the synthesis gel having molar composition of SiO₂:0.1TPABr:0.9Et₂NH:0.03TiO₂:80H₂O:0.06H₃PO₄ at 150 °C for 48 h showed the highest oxidation conversion of IPA of 72% accompanied by a flux of 0.35 kg/m² h. Further more, much higher IPA oxidation conversion of 76% accompanied by a flux of 0.65 kg/m² h was obtained for the TS-1 zeolite membrane prepared with the same synthesis gel by “seeding in situ” method at 150 °C for 72 h.     

Investigation of the interactions between ginsenosides and amino acids by mass spectrometry and theoretical chemistry

In order to evaluate the essence of the interactions of ginsenosides and proteins which are composed by α-amino acids, electrospray ionization mass spectrometry was employed to study the noncovalent interactions between ginsenosides (Rb₂, Rb₃, Re, Rg₁ and Rh₁) and 18 kinds of α-amino acids (Asp, Glu, Asn, Phe, Gln, Thr, Ser, Met, Trp, Val, Gly, Ile, Ala, Leu, Pro, His, Lys and Arg). The 1:1 and 2:1 noncovalent complexes of ginsenosides and amino acids were observed in the mass spectra. The dissociation constants for the noncovalent complexes were directly calculated based on peak intensities of ginsenosides and the noncovalent complexes in the mass spectra. Based on the dissociation constants, it can be concluded that the acidic and the basic amino acids, Asp, Glu, Lys and Arg, bound to ginsenosides more strongly than other amino acids. The experimental results were verified by theoretical calculations of parameters of noncovalent interaction between ginsenoside Re and Arg which served as a representative example. Two kinds of binding forms, “head–tail” (“H–T”) and “head–head” (“H–H”), were proposed to explain the interaction between ginsenosides and amino acids. And the interaction in “H–T” form was stronger than that in “H–H” form.     

On the ionic conductivity and phase transitions in the Li2SO4---Li2WO4 system and their relation to ion transport mechanism

Secco et al. have performed several measurements of ionic conductivity, which they have considered as “convincing evidence” that the “paddle-wheel” mechanism does not contribute significantly to ion conductivity in Li₂SO₄-based compositions. However, a comparison of their results in the high-conductivity range with those of other investigators suggests that their data are artifacts. The cause of this is that the resistance of their sulfate-rich samples is about 0.1 ohm at high temperatures. Thus, their results are reliable only for “normal,” i.e., low, conductivities. It is briefly summarized why the “paddle-wheel” mechanism for ion transport is superior to a percolation-type mechanism for a few high-conducting phases.     

Preparation of alpha-elastin nanoparticles by gamma irradiation

Nanoparticles were prepared by utilizing the thermosensitive aggregation of alpha-elastin and gamma ray crosslinking. Three different heating process, “Slow heating”, “Fast heating”, and “Heat shock”, were applied for the aggregation of the alpha-elastin and examined to yield nanoparticles by gamma rays crosslinking. As a result, only “Slow heating” process yielded nanoparticles with diameters of about ca. 300 nm above cloud point (CP) and about ca. 100 nm below CP, and a narrow size distribution above 1.0 mg/ml concentration (exclude 1.0 mg/ml).     

Effect of “Hot Termini” and Properties of Organic Compounds. A Quantitative Consideration and Simple Example

Differences in various properties of organic compounds of different classes of the same or similar composition but of different structure, as well as complexes of such compounds and transient complexes in their chemical reactions are associated with different mobility of terminal molecular fragments and can be explained in terms of the “hot termini” effect.__________Translated from Zhurnal Obshchei Khimii, Vol. 75, No. 1, 2005, pp. 82–88.Original Russian Text Copyright © 2005 by Golovanov, Zhenodarova.     

Nanotechnologies for drug delivery: Application to cancer and autoimmune diseases

Polymer-based nanotechnologies are now proposed as an alternative to classical formulations for drug administration, delivery and targeting. Therapeutic applications of the first generation of nanotechnologies include the treatment of cancer liver diseases. Avoiding the recognition by the liver is also possible by developing long circulating polymeric colloidal carriers (“stealth” systems) able to avoid the opsonization process and the recognition by the macrophages. The design of such carriers of second generation is based on the physico-chemical concept of the “steric repulsion”: by grafting polyethyleneglycol chains at the surface of nanoparticles, the adsorption of seric proteins may be dramatically reduced due to steric hindrance. Such an approach allows maintaining the drug carrier for a longer time into the circulation and the resulting extravasation towards non reticuloendothelial-located cancers may become possible. Now, new applications and exciting perspectives are proposed for the delivery of drugs to previously non accessible diseased sanctuaries, like the brain (treatment of glioma and autoimmune diseases of the brain) or the ocular tissues (treatment of the autoimmune uveitis). Finally, the use of nanotechnologies for the delivery of nucleic acids (oligonucleotides) is also discussed in this review.     

Comparison of chemometric methods for brand classification of cigarettes by near-infrared spectroscopy

The combinations of NIR spectroscopy and three classification algorithms, i.e., multi-class support vector machine (BSVM), k-nearest neighbor (KNN) and soft independent modeling of class analogies (SIMCA), for discriminating different brands of cigarettes, were explored. The influence of the training set size on the relative performance of each algorithm was also investigated. A NIR spectral dataset involving the classification of cigarettes of three brands was used for illustration. Three performance criteria based on “correctly classified rate (CCR)”, i.e., “Average CCR”, “95 percentile of CCR” and “S.D. of CCR”, were defined to compare different algorithms. It was revealed that BSVM is significantly better than KNN or SIMCA in the statistical sense, especially in cases where the training set is relatively small. The results suggest that NIR spectroscopy together with BSVM could be an alternative to traditional methods for discriminating different brands of cigarettes.     

Reply to “Comments on the paper entitled ‘The formulation and modelling of the anodic dissolution of zinc through adsorbed intermediates’ ” by C. Cachet et al.

The points raised in the paper entitled “Comments on the paper entitled ‘The formulation and modelling of the anodic dissolution of zinc through adsorbed intermediates”’ have been discussed. It has been shown that, in contrast to the statements in the “Comments”, most of the papers concerning the reaction schemes suggested for the interpretation of the dissolution or deposition of metals, which were considered as a support for the opinion of the Authors of the “Comments”, support the views expressed in our original paper [J. Electroanal. Chem. 583 (2005) 148]. On the other hand, it has been stressed again that the criticism expressed in the original paper refers to dubious conclusions drawn on the basis of transient measurements.     

Metal Nanoparticles on Polymer Surfaces: 5. Catalytic Activity of Colloidal Platinum Films Incorporated in Polystyrene Surface Layer

The fundamental possibility to enlarge Pt nanoparticles in monolayer ensembles formed on polystyrene surfaces by the adsorption from hydrosol in solution of isopropanol and K₂PtCl₄ is demonstrated for the first time. The enlargement of “seeding” nanoparticles is performed after their preliminary incorporation (partial embedding) into the polymer surface layer by the annealing of a system within the range between “surface” and “bulk” glass transition temperatures of polystyrene. It is shown that a colloidal film of metallic platinum with a thickness up to 200 nm is formed in the course of enlargement and it is mechanically fixed in the polymer surface layer. Such a system exhibits, over a long time, high catalytic activity in the model reaction of methyl viologen reduction with hydrogen.__________Translated from Kolloidnyi Zhurnal, Vol. 67, No. 3, 2005, pp. 398–403.Original Russian Text Copyright © 2005 by Rudoy, Sukhov, Dement’eva, Abkhalimov, Vereshchagina, Kartseva, Ershov.     

Reminiscences and lessons on the occasion of a silver jubilee

This paper, written to commemorate the publication of Walsh's classical paper on the potentialities of atomic absorption spectroscopy (AAS) 25 years ago, contains nothing new. It is a personal recollection of the work done independently at our laboratory prior to 1955 which resulted in the construction of a “negative filter” (for use in atomic emission spectroscopy) and an “absorption flame photometer.” Some lessons are drawn from the historical development of AAS about the inventing of new analytical methods in general.     

Optimization of lipospheres production by factorial design and their performances on a dielectrophoretic lab-on-a-chip platform

Aim of this study was to investigate the effect of the preparation parameters on the characteristics of lipospheres that would optimally fit to a lab-on-a-chip platform. Lipospheres were produced by melt dispersion technique using different lipid mixture heated to 70 °C and then emulsified into an external aqueous phase. The initial part of the work was devoted to the selection of the best lipid composition by a classical intuitive approach while the optimization and the screening of the experimental parameters were conducted through a “design of experiments”. Once the best preparation parameters were selected, they were adopted also for the production of cationic lipospheres (CLS). The second part of the study describes the analysis of the lipospheres performances when applied to a DEParray™Chip. The loading, distribution, movement and separation of neutral and cationic lipospheres were investigated. The obtained data show that both neutral and cationic lipospheres can be efficiently used in association with DEParray™Chip.     

A thermodynamic interpretation of the behavior of higher fatty alcohols and acids upon the chromatographic paper

An idea was presented of treating the chromatographed substance as a “solute,” and the chromatographic system, composed of the stationary and the mobile phase as a “solvent.” Moreover the concept of “local equilibrium” was introduced, allowing to regard a given chromatographic spot as a “binary solution.” Thus a possibility arose to apply the classical thermodynamic approach, normally used for binary solutions, and namely: μ_i = μ_i + RT ln x_iƒ_i, where μ_i—chemical potential of the “i”-th compound in the solution, μ_i—chemical potential of the pure “i”-th compound, x_i-molar fraction of the “i”-th compound, ƒ_i—its activity coefficient, in a modified form, suitable for the chromatographic purpose.