Elisabetta Bonometti

Volatile Signals During Pregnancy: A Possible Chemical Basis for Mother–Infant Recognition

Human pheromones play a role in regulating relationships and apparently influence partner choice and mother–infant recognition. We analyzed the chemical content of volatiles from sweat patch samples from the para-axillary and nipple–areola regions of women during pregnancy and after childbirth. Solid phase microextraction was used to extract the volatile compounds, which were then characterized and quantified by gas chromatography–mass spectrometry. During pregnancy, women developed a distinctive pattern of five volatile compounds common to the para-axillary and nipple–areola regions (1-dodecanol, 1-1′-oxybis octane, isocurcumenol, α-hexyl-cinnamic aldehyde, and isopropyl myristate). These compounds were absent outside pregnancy and had slightly different patterns in samples from the two body areas. Differentiation of the volatile patterns among pregnant women may help newborns to distinguish their own mothers.

CARBON INFLUENCE IN THE SYNTHESIS OF MgB2 BY A MICROWAVE METHOD

We describe a method to produce MgB2 bulk via a microwave processing, which has not been reported yet for this material. We used two experimental arrangements, which were different in the form of the graphite thermal activator responsible for the microwave absorption. The reaction products have been analyzed from the morphological, structural and electronic point of view. The results show that the critical temperature is decreased by about 4 K when the graphite can diffuse inside the reaction cell and is incorporated in the samples, even if no evidence of carbon substitution in the MgB2 lattice is given by the lattice constants. We point out that excellent conductivity features are achieved for nearly carbon-free samples.

Electrical transport effects due to oxygen content modifications in a Bi2Sr2CaCu2O8+δ superconducting whisker

We report a set of resistivity measurements along the α-axis of a Bι 2 Sr 2 CaCu 2 Ο 8 +δ microscopic superconducting whisker. The effect of the storage environment on sample ageing has been studied, considering both an air atmosphere at 273 K and a helium atmosphere at about 300 K for an overall storage time of about 100 days. It is clearly shown that the material underwent a remarkable resistivity increase of 26% at 260 K accompanied by a decrease in the critical temperature of 0.6 K during the whole ageing period. The helium atmosphere increased the average process rate by about two orders of magnitude. The present results are in agreement with previous findings on room temperature structural modifications in Bι 2 Sr 2 CaCu 2 Ο 8+δ whiskers and can be ascribed to oxygen depletion phenomena from the material.

DC Shielding Properties of Coaxial MgB2/Fe Cups

We investigated the efficiency in magnetic field mitigation of superimposed MgB2/Fe coaxial cups with cylindrical symmetry, subjected to an applied magnetic field parallel to their axis. The MgB2 cup was grown by a microwave-assisted Mg-liquid infiltration technique in a boron preform. This technique allows obtaining samples with a reduced amount of unreacted magnesium, shape chosen before the growth procedure, and easily scalable sizes. Local magnetic induction measurements were carried out by means of a cryogenic Hall probe mounted on a custom-designed stage moveable along the sample axis with micrometric resolution. The measurements were performed at 20 K and 30 K, in magnetic field up to 1.5 T, as a function of the external source field, of the position and of time. At higher magnetic fields the superposition of the Fe cup on the MgB2 one allows obtaining a shielding efficiency 3-4 times higher than that measured with the single superconducting cup. The magnetic induction relaxation rate is also strongly reduced. On the contrary, a decrease of the shielding efficiency of the hybrid system with respect to the MgB2 cup alone turns out at low magnetic field. Numerical simulations indicate a reduction of this worsening by a protrusion of the superconducting cup above the ferromagnetic one.

DC Shielding Properties of Coaxial Cups

We investigated the efficiency in magnetic field mitigation of superimposed MgB2/Fe coaxial cups with cylindrical symmetry, subjected to an applied magnetic field parallel to their axis. The MgB2 cup was grown by a microwave-assisted Mg-liquid infiltration technique in a boron preform. This technique allows obtaining samples with a reduced amount of unreacted magnesium, shape chosen before the growth procedure, and easily scalable sizes. Local magnetic induction measurements were carried out by means of a cryogenic Hall probe mounted on a custom-designed stage moveable along the sample axis with micrometric resolution. The measurements were performed at 20 K and 30 K, in magnetic field up to 1.5 T, as a function of the external source field, of the position and of time. At higher magnetic fields the superposition of the Fe cup on the MgB2 one allows obtaining a shielding efficiency 3-4 times higher than that measured with the single superconducting cup. The magnetic induction relaxation rate is also strongly reduced. On the contrary, a decrease of the shielding efficiency of the hybrid system with respect to the MgB2 cup alone turns out at low magnetic field. Numerical simulations indicate a reduction of this worsening by a protrusion of the superconducting cup above the ferromagnetic one.

Preparation Of Germanium Monosulfide Particles By Microwave Assisted Sublimation

Abstract GeS spherical particles in the μ-nm range can be rapidly obtained by sublimation under inert gas flow from a microwave heated mixture of GeS and graphite. The sublimed material has been characterised by XRD, MS and Raman spectroscopy.

A new heterometallic multiligand 3D coordination polymer: synthesis and structure of [Pb(OH)]n[Ag(SCN)(CN)]n

The synthesis and structural characterization of a new coordination polymer [Pb(OH)]n[Ag(SCN)(CN)]n, formed by an anionic layer [Ag(CN)(μ3-SCN)]nn− linked to the 1D cationic fragment [Pb(OH)]n through a bridging cyanide, is reported. We have obtained a rational combination of the pattern of laurionite-type structures (Pb(OH)X, with X = halogen, SCN) with the 2D hexagonal pattern of the silver thiocyanate. The title compound shows luminescent behaviour, and the analysis of the computed band structure allows us to describe the electronic transitions.

Reticular chemistry studies on CuCN derivatives for new luminescent materials

The construction of coordination polymers has been rationalized through the use of database and a topological approach. The reticular chemistry is based on the specific geometry of tectons that, by combination, form a predictable topology. This abstract procedure, in presence of nodes with a specific coordination form and of directional interactions, allows to obtaining a desired topology. This is often connected with the properties of the materials, like porosity, NLO properties and magnetism. Cyanide is a good ligand in reticular chemistry: its linearity in coordination bond makes equivalent both the coordination form and the coordination polyhedron of metal centers, and permits to clarify the derived structures. Although the lot of work done in recent years [1], some systems are very complex and less predictable than others. For example, the Cu(I)CN system is interesting because this salt, that forms linear polymer in the solid state [2], became very complex in presence of ancillary ligands. Cu(I) metal centers can have different coordination numbers and different coordination geometries. On the other hand, the cyanide itself has a multiform behavior in this system: the μ2 bridging mode , the terminal one and the combination of different bridging behaviors have been observed. For this reasons, a clearly predictable nodal geometry and a defined topological derivation is difficult to obtain, and a lot of work has still to be done. We focalized our attention on three different aspects. The first one is the presence of a terminal or briging ligand with different sterical requirements: to obtain some clarifying informations, we synthesized seven new derivatives of substituted and unsubstituted thioureas, and from their characterization and from a statistical analysis of Databases we correlate the nature of the ligand and the topology of the derived compounds. The second aspect is the effect of the partial substitution of Cu(I) with Cu(II) ion on the topology: to pursue a rationalization, we synthesized and structurally characterized six mixed Cu(I)/Cu(II) coordination polymers that will be commented. The third aspect is the presence of bi-chelating ligands of different rigidity and symmetry (2,2’-terpyridine and 2-(2’pyridyl)-1,8-naphthyridine) on the topology of the derived coordination polymers. This family of ligands, differently from the monochelating ones that follow the usual 1D wavy topology typical of terminal ligands, allows to construct interesting 2D-nets with {63} point symbol [3] and the presence of cuphrophilic interaction based on Secondary Building Units. We synthesized and structurally characterized two new compounds and the effects that favour the previous cited topology will be commented. All the previous analysis have been undertaken in the search of optimal luminescence for LED materials, and a full solid state luminescence characterization of all the 16 CuCN derivatives here presented has been done. In this communication, we will comment the principal effects influencing this property.

DC Shielding Properties of Coaxial

We investigated the efficiency in magnetic field mitigation of superimposed MgB2/Fe coaxial cups with cylindrical symmetry, subjected to an applied magnetic field parallel to their axis. The MgB2 cup was grown by a microwave-assisted Mg-liquid infiltration technique in a boron preform. This technique allows obtaining samples with a reduced amount of unreacted magnesium, shape chosen before the growth procedure, and easily scalable sizes. Local magnetic induction measurements were carried out by means of a cryogenic Hall probe mounted on a custom-designed stage moveable along the sample axis with micrometric resolution. The measurements were performed at 20 K and 30 K, in magnetic field up to 1.5 T, as a function of the external source field, of the position and of time. At higher magnetic fields the superposition of the Fe cup on the MgB2 one allows obtaining a shielding efficiency 3-4 times higher than that measured with the single superconducting cup. The magnetic induction relaxation rate is also strongly reduced. On the contrary, a decrease of the shielding efficiency of the hybrid system with respect to the MgB2 cup alone turns out at low magnetic field. Numerical simulations indicate a reduction of this worsening by a protrusion of the superconducting cup above the ferromagnetic one.

\hbox{MgB}_{2}/ \hbox{Fe}

In this article we report for the first time on the preparation of small, amorphous, metastable GeS particles by microwave assisted sublimation. The preparation of spherical small crystal particles (0.1-4.2 mm) of GeS by microwave assisted sublimation of pure GeS has been already reported [22]. Germanium sulfides are semiconductors and they have been studied for their chemical and physical properties in crystal and vitreous state [5]. Preparation of small particles of GeS 2 can be achieved by polycondensation of [(CH 3 ) 4 N] 4 -Ge 4 S 10 under acidic conditions (3) or by sol-gel technique (about 0.4 mm size) [8, 14]. The formation of vitreous GeS 2 , by rapid quenching of liquid GeS 2 , has been reported [10]. Though recently weakened protonated GeS 2 has been prepared by sublimation of GeS 2 + H 2 S at about 1020K and 7·10 Pa, pure molecular GeS 2 can not be obtained in pure form by sublimation of solid GeS 2 because equilibrium reaction (I) is shifted to the right by the temperature increase [19, 20]. Nevertheless equilibrium (I) has been used to calculate the standard molar enthalpy of the formation for GeS 2 (cr) and for the chemical transport of Ge [1, 2]. However no evidence has been found for the formation of vitreous GeS in bulk or particles, although vitreous GeS has been prepared in thin films [11, 12]. Some different spectroscopic properties have been studied in glassy and crystalline GeS 2 as in glassy and crystalline GeS [12, 21]. Preparation of small particles from vapour phase, namely gas to particle conversion, is a widely used technique [9]. It has been obtained by microwave plasma, aerosol pyrolysis, and flame hydrolysis but these techniques have the disadvantage of difficult control of particle agglomeration [15, 16, 17, 18]. These kinds of preparations need high temperatures. To obtain amorphous nanoparticles we started from GeS 2 according to the well known, but probably not well understood reaction (I) [3]: