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.     

“Model-free” kinetic analysis?

All kinetic analyses aim to determine a sufficient number of kinetic parameters, usually at least an apparent Arrhenius activation energy and pre-exponential factor, and a conversion function or kinetic model (making up a ‘kinetic triplet’), so that accurate extrapolations of kinetic behaviour can be made. “Model-free” methods of kinetic analysis postpone the problem of identifying a suitable kinetic model until an estimate of the activation energy has been made. A major reason for doing this is that misidentification of the kinetic model has a marked effect on the values obtained for the Arrhenius parameters in both isothermal and non-isothermal kinetic analyses. Some aspects of this problem are discussed.

The non-parametric kinetics (NPK) method [1 and 2] is a “model-free” method of kinetic analysis that does not seem to have received the attention that it deserves. This is probably because of its mathematical sophistication and the fact that the matrix and non-linear regression calculations involved are not readily automated. The principle of the method appears to be that of “forcing” a set of non-isothermal data into the set which should have been obtained if the experiments had been carried out isothermally. The method deserves wider testing and also raises some interesting aspects of the philosophy behind non-isothermal kinetic analysis.     

Syntheses of heparin - like pentamers containing “opened” uronic acid moieties

The syntheses of four analogues of pentasaccharide Ia, which corresponds to the minimal AT III binding region of heparin, are presented and the biological activities of these analogues will be discussed. Three of these analogues (i.e. compounds II, III and IV) contain an R-glyceric acid oxymethylene residue (i.e. B in fig.3) instead of -L-iduronic acid and in the other analogue (i.e. compound V) the β-D-glucuronic acid unit has been replaced by an s-glyceric acid oxymethylene residue (i.e. A in fig3). The R and S-glyceric acid oxymethylene residues represent an “opened” iduronic acid unit and an “opened” glucuronic acid unit, respectively, containing the essential carboxylate function in the appropriate configuration. The crucial step in the syntheses of these “opened” uronic acid pentamer analogues, was the preparation of the required glyceric acid oxymethylene residues 8a, 8b and 8c.

Analogues II and III, containing an “opened” iduronic acid moiety, display a significant AT III mediated Xa activity. Compound III contains two extra sulphate groups at unit 2. Removal of the contributing O-sulphate groups at position 3 and 6 of unit 6 of compound II (i.e. compound IV) results in a seven-fold drop in Xa activity. Replacement of the β-D-glucuronic acid unit by an S-glyceric acid oxymethylene residue (i.e. compound V) leads to almost a complete loss of Xa activity, notwithstanding the fact that all the essential and contributing charged groups are present in the molecule.     

“Superpermeability” and “pumping” of atomic hydrogen through palladium membranes

Permeation of atomic as well as molecular hydrogen through palladium membranes has been investigated experimentally in the temperature range from room temperature to 200 °C and at a higher incident flux of hydrogen atoms on palladium surface than in previous studies. The results demonstrate that phenomena of ‘superpermeability’ and ‘pumping’ of atomic gases through metal membranes are of a common nature. A theoretical model based on chemical thermodynamics and diffusion theory adequately describes the quantitative relationships observed in experiments. It was found that permeability of atomic hydrogen depends strongly on the magnitude of surface incident flux and membrane temperature.     

A novel “green” synthesis of starch-capped CdSe nanostructures

This paper reports a “green” facile, room temperature, one-pot synthesis of starch-capped CdSe nanostructures with an obvious quantum confinement effect via a novel non-organometallic method. It is found that by simply tuning the Cd:Se molar ratio, dots and elongated particles of high aspect ratio could be prepared selectively in the presence of the same ligand concentration without any post-treatment. Spherical particles were produced at 1:1 ratio, while elongated particles were produced at 0.5:1 Cd:Se ratio. The X-ray diffraction (XRD) analysis showed that the particles were predominantly of wurtzite structure, with sharp diffraction patterns regardless of their size and shapes. We inferred that the elongated particles are formed by self-reorganisation occurring via adhesion between the spherical nanoparticles as a result of dipole–dipole interactions.     

Structural and magnetic properties of “one-dimensional” barium vanadium triselenide

BaVSe₃ has been synthesized and its crystal structure determined at 293(2)°K. The structure was solved in the hexagonal space group P6₃/mmc (D⁴_6h), with a = 6.9990(11) and c = 5.8621(13) Å. Scans (2 Θ) of a polycrystalline sample revealed that BaVSe₃ undergoes a transition to an orthorhombic unit cell (b′ 3^1/2 a, a′ a, c′ c) at 303(5)°K. Magnetic susceptibility measurements between 4 and 300°K indicate that BaVSe₃ is paramagnetic down to 41(1)°K, where magnetic ordering occurs, with a magnetic moment in the ordered phase of 0.2 μ_B per vanadium atom. The orthorhombic lattice distortion may be caused by the “freezing in” of “soft” vibrational modes.     

Surface Activation of Pt Nanoparticles Synthesised by “Hot Injection” in the Presence of Oleylamine

Oleylamine (OA) based “hot injection” colloidal synthesis offers a versatile approach to the synthesis of highly monodisperse metallic and multi‐metallic alloyed nanostructures in the absence of potentially toxic and unstable phosphine compounds. For application in heterogeneous catalysis and electrocatalysis, the adsorbed OA species at the metal surfaces should be effectively removed without compromising the structure and composition of the nanostructures. Herein, we investigate the removal of OA from colloidal Pt nanoparticles through 1) “chemical methods” such as washing in acetic acid or ethanol, and ligand exchange with pyridine; and 2) thermal pre‐treatment between 185 and 400 °C in air, H₂ or Ar atmospheres. The electrochemical reactivity of Pt nanoparticles is acutely affected by the presence of surface organic impurities, making this material ideal for monitoring the effectiveness of OA removal. The results showed that thermal treatment in Ar at temperatures above 400 °C provides highly active particles, with reactivity comparable to the benchmark commercial catalyst, Pt/ETEK. The mechanism involved in thermal desorption of OA was also investigated by thermogravimetric analysis coupled to mass spectrometry (TGA‐MS). Oxidation of HCOOH and adsorbed CO in acidic solution were used as test reactions to assess the Pt electrocatalytic activity.     

Vapor liquid equilibrium modeling of alkane systems with Equations of State: “Simplicity versus complexity”

Two types of Equations of State (EoS), which are characterized here as “simple” and “complex” EoS, are evaluated in this study. The “simple” type involves two versions of the Peng–Robinson (PR) EoS: the traditional one that utilizes the experimental critical properties and the acentric factor and the other, referred to as PR-fitted (PR-f), where these parameters are determined by fitting pure compound vapor pressure and saturated liquid volume data. As “complex” EoS in this study are characterized the EoS derived from statistical mechanics considerations and involve the Sanchez–Lacombe (SL) EoS and two versions of the Statistical Associating Fluid Theory (SAFT) EoS, the original and the Perturbed-Chain SAFT (PC-SAFT).

The evaluation of these two types of EoS is carried out with respect to their performance in the prediction and correlation of vapor liquid equilibria in binary and multicomponent mixtures of methane or ethane with alkanes of various degree of asymmetry. It is concluded that for this kind of systems complexity offers no significant advantages over simplicity. Furthermore, the results obtained with the PR-f EoS, especially those for multicomponent systems that are encountered in practice, even with the use of zero binary interaction parameters, indicate that this EoS may become a powerful tool for reservoir fluid phase equilibria modeling.     

An experimental study on the “sequential order” rules in generalized two-dimensional correlation spectroscopy

Following our theoretical analysis on the “sequential order” rules in generalized two-dimensional (2D) correlation spectroscopy (H. Huang, Anal. Chem. 79 (2007) 8281–8292), an experimental study was conducted to test the “sequential order” rules using the FT-NIR data of poly(3-hydroxybutyrate) (PHB)/poly(l-lactic acid) (PLA) blends under uniaxial elongation and parallel polarization. The local sequential order concept proposed for the generalized two-dimensional (2D) correlation spectroscopy is now more clearly stated; “the intensity change at ν1 occurs predominantly before ν2” means that the starting time of the intensity change at ν1 is prior to that at ν2. It is this local sequential order which reflects the real and intuitive sequential order between two events in generalized situations. It has been found that the integrated/overall sequential order results obtained from the 2D correlation analysis may be contradictory to the intuitive local sequential order. In addition, different integrated/overall sequential orders could be obtained by selection of different sampling intervals from a certain set of experimental data, or choosing different number of the contours for the same sampling interval. These new experimental findings are a perfect reinforcement to our previous theoretical study and have further demonstrated the uncertainty of applying the “sequential order” rules in generalized 2D correlation spectroscopy.     

Platinum Group Organometallics Based on “Pincer” Complexes: Sensors,Switches, and Catalysts

Since the first reports in the late 1970s on transition metal complexes containing pincer‐type ligands—named after the particular coordination mode of these ligands—these systems have attracted increasing interest owing to the unusual properties of the metal centers imparted by the pincer ligand. Typically, such a ligand comprises an anionic aryl ring which is ortho,ortho‐disubstituted with heteroatom substituents, for example, CH₂NR₂, CH₂PR₂ or CH₂SR, which generally coordinate to the metal center, and therefore support the M−C σ bond. This commonly results in a terdentate and meridional coordination mode consisting of two metallacycles which share the M−C bond. Detailed studies of the formation and the properties of a large variety of pincers containing platinum group metal complexes have provided direct access to both a fundamental understanding of a variety of reactions in organometallic chemistry and to a range of new applications of these complexes. The discovery of alkane dehydrogenation catalysts, the mechanistic elucidation of fundamental transformations (for example, C−C bond activation), the construction of the first metallodendrimers for sustainable homogeneous catalysis, and the engineering of crystalline switches for materials processing represent only a few of the many highlights which have emanated from these numerous investigations. This review discusses the synthetic methodologies that are currently available for the preparation of platinum group metal complexes containing pincer ligands and especially emphasizes different applications that have been realized in materials science such as the development and engineering of sensors, switches, and catalysts.     

A new method for “ferrous iron” and “excess oxygen” in rocks, minerals, and oxides

A new method is given whereby oxygen excess or deficiency in many minerals and oxides may be simply determined. The method depends on the stability in phosphoric acid-pyrophosphate mixtures of both Mn^III and Mn^II. The sample is dissolved in a phosphoric acid mixture containing excess Mn^II, with or without the addition of standard oxidant, and Mn^III remaining in solution or produced by reaction with the sample is titrated with ferrous ammonium sulphate, using barium diphenylamine sulphate as indicator. The method is useful in many cases where existing methods are inapplicable or unsatisfactory. Accurate results can be obtained using relatively small samples.     

Fused‐Ring Formation by an Intramolecular “Cut‐and‐Sew” Reaction between Cyclobutanones and Alkynes

The development of a catalytic intramolecular “cut‐and‐sew” transformation between cyclobutanones and alkynes to construct cyclohexenone‐fused rings is described herein. The challenge arises from the need for selective coupling at the more sterically hindered proximal position, and can be addressed by using an electron‐rich, but less bulky, phosphine ligand. The control experiment and ¹³C‐labelling study suggest that the reaction may start with cleavage of the less hindered distal C?C bond of cyclobutanones, followed by decarbonylation and CO reinsertion to enable Rh insertion at the more hindered proximal position.     

Minor and trace element contents in pituitary gland of “normal” humans: an evaluation of analytical data

In the study of trace elements in the different human brain areas, a critical evaluation of the values available in the literature is of great importance in attempting to establish reliable baseline levels, i.e., Reference Values (RVs) for toxicological assessment studies.This paper reviews the published values of minor and trace elements in the pituitary gland (hypophysis) of “normal” humans.Eighteen published papers are taken into account, 15 of which refer to the entire gland, whereas in three of them, only the adenohypophysis is considered.It turns out that essential elements such as Cu, Fe, Se and Zn were more frequently determined, whereas As, Br, Ca, Co, Cr, Cs, K, Mg, Mn, Ni and Rb were seldom investigated.Mercury was determined by several authors because of the concern caused by Hg release from dental amalgam fillings.Most values were obtained by Neutron Activation Analysis (NAA), which appears to have played a pioneer role in this field.Literature data on trace element levels in pituitary gland are at present insufficient to establish RVs; rather, they can be considered only as indicative values.Future investigations based on large populations of control subjects, with standardization of the preanalytical factors and the use of fit-for-purpose Standard or Certified Reference Materials (SRMs, CRMs) should therefore be envisaged.     

Consumer attitudes to radiation and irradiated potatoes at “radiation fair” in Osaka, Japan

“Radiation Fair” has been held in summer vacation season in August for more than 10 years in Osaka, the largest city of western Japan, for the purpose of public education and information transfer of radiation and radiation-related technology. We distributed questionnaires to the visitors for recent 3 years to inquire their status toward radiation and irradiated products including irradiated potatoes as well as impression toward the displays. According to the survey results, more than 60% of the kids visitors were satisfied with this exhibition as informative, more than half of the older visitors (16 years old and upward) indicated that they recognized the word of “radiation” when they were at elementary school and the most significant sources of this information were school lessons and the mass media. Consumer's image toward radiation seems to shift to more “positive” when correct knowledge about radiation is given. More than half of consumers did not know “irradiated potatoes” but the percentage indicating that irradiated potatoes was definitely hazardous was less than 10%.     

Solvent crazing of “dry” polystyrene and “dry” crazing of plasticized polystyrene

The critical strain ε_c for crazing of polystyrene in each of a variety of organic liquids has been measured along with the degree of swelling of the polymer by the liquid and the attendant reduction in the glass transition temperature T_g of the polymer. The critical strain for the crazing in air and the T_g of each of a set of specimens molded from mixtures of o-dichlorobenzene and polystyrene have also been determined. Correlations of ε_c with T_g in the two cases are identical within experimental error for the first 40°C of T_g reduction; these results imply (1) that organic liquids do not exercise a significant surface energy role in solvent crazing and (2) that their only roles are associated with flow processes. Correlation of solvent crazing ε_c with solubility parameter of the crazing fluid is very poor for several reasons that are discussed.     

“Hole-burning spectra”. A new method for obtaining fine structure in absorption spectra of organic molecules

A new method is proposed for obtaining fine structure in broad-band absorption spectra of organic molecules in solid solutions at low temperature. This method is based on the laser burning of a series of narrow gaps in inhomogeneously broadened absorption spectra. A special spectral set-up has been developed for the measurement of the differential spectrum (a “hole-burning spectrum”) of “burnt” and “unburnt” samples. As an example the hole-burning spectrum of Zn-tetraphenylporphine in ethanol has been considered.     

Investigation of coherence transfer between “CH3” and “CH2” groups in ethanol with time-resolved multiplex CARS technique

The coherence transfer between stretching vibration modes of C–H bonds in the ethanol is detected by time-resolved multiplex CARS technique and it occurs via “through-bond transfer” pathway. The time scale and velocity of coherence transfer are estimated at 90 fs and 1670 m/s. Moreover, coherence transfer process requires vibrational modes of acceptor and donor are different.     

“intelligent” polymers in medicine and biotechnology

One can define “intelligent” polymers as those polymers which respond with large property changes to small physical or chemical stimuli. These polymers may be in various forms, such as in solution, on surfaces, or as solids. One may also combine “intelligent” aqueous polymer systems with biomolecules, to yield a large family of polymers which respond “intelligently” to physical, chemical or biological stimuli. This article overviews such interesting and versatile polymer systems.     

Comment on “chiral discrimination in spherical tops”

The difference in the interaction energies of two co-rotating, and two counter-rotating, spherical-top molecules is of second order in the rotational constant B, and not first order. Co- and counter-spinning alkali-metal atoms exhibit a similar but numerically much larger “chiral” discrimination.     

Applications of “Hot” and “Cold” Bis(thiosemicarbazonato) Metal Complexes in Multimodal Imaging

The applications of coordination chemistry to molecular imaging has become a matter of intense research over the past 10 years. In particular, the applications of bis(thiosemicarbazonato) metal complexes in molecular imaging have mainly been focused on compounds with aliphatic backbones due to the in vivo imaging success of hypoxic tumors with PET (positron emission tomography) using ⁶⁴CuATSM [copper (diacetyl‐bis(N4‐methylthiosemicarbazone))]. This compound entered clinical trials in the US and the UK during the first decade of the 21^st century for imaging hypoxia in head and neck tumors. The replacement of the ligand backbone to aromatic groups, coupled with the exocyclic N's functionalization during the synthesis of bis(thiosemicarbazones) opens the possibility to use the corresponding metal complexes as multimodal imaging agents of use, both in vitro for optical detection, and in vivo when radiolabeled with several different metallic species. The greater kinetic stability of acenaphthenequinone bis(thiosemicarbazonato) metal complexes, with respect to that of the corresponding aliphatic ATSM complexes, allows the stabilization of a number of imaging probes, with special interest in “cold” and “hot” Cu(II) and Ga(III) derivatives for PET applications and ¹¹¹In(III) derivatives for SPECT (single‐photon emission computed tomography) applications, whilst Zn(II) derivatives display optical imaging properties in cells, with enhanced fluorescence emission and lifetime with respect to the free ligands. Preliminary studies have shown that gallium‐based acenaphthenequinone bis(thiosemicarbazonato) complexes are also hypoxia selective in vitro, thus increasing the interest in them as new generation imaging agents for in vitro and in vivo applications.