Petrographic, biological, and chemical techniques used to characterize two tombs in the Protestant Cemetery of Rome (Italy)

In this multidisciplinary contribution, several diagnostic tests were carried out in order to characterize the stone materials, forms of alteration, and protective products applied in the past to two monumental tombs located in the Protestant Cemetery of Rome (Italy).     

The effect of solvent on the morphology of ZnO nanostructure assembly by dielectrophoresis and its device applications

Different zinc oxide nanostructured morphologies were grown on photolithographically patterned silicon/silicon dioxide substrates by dielectrophoresis technique using different solvents, such as water and ethanol, obtaining rod-like and net-like nanostructures, respectively. The formation of continuous nanostructures was confirmed by scanning electron microscopic, atomic force microscopic images, and electrical characterizations. The rod-like zinc oxide nanostructures were observed in the 10 μm gap between the fingers in the pattern, whereas net-like nanostructures were formed independently of microgap. A qualitative study about the mechanism for the assembly of zinc oxide continuous nanostructures was presented. Devices were electrically characterized, at room temperature, in controlled environment to measure the conductance behavior in ultraviolet and humidity environment. Devices based on zinc oxide nanostructures grown in ethanol medium show better responses under both ultraviolet and humidity, because of the net-like structure with high surface-to-volume ratio.     

Layer-by-layer assembled composite films of side-functionalized poly(3-hexylthiophene) and CdSe nanocrystals: electrochemical, spectroelectrochemical and photovoltaic properties

Regioregular poly(3-hexylthiophene) containing one diaminopyrimidine side group per ten repeat units (P3HT-co-P3(ODAP)HT) can form molecular composites with 1-(6-mercaptohexyl)thymine capped CdSe nanocrystals (CdSe(MHT)) via hydrogen bonds directed molecular recognition. Here we report complementary spectroscopic, electrochemical and spectroelectrochemical investigations of both the functionalized poly(thiophene) and its composite with the nanocrystals, the latter being fabricated using the layer-by-layer (LbL) deposition technique. UV-Vis-NIR and Raman spectroelectrochemical investigations unequivocally show that the onset of the first anodic peak in the cyclic voltammogram of the copolymer can be attributed to the oxidation of the pi-conjugated backbone in the polymer chains. For this reason, it is possible to determine the width and the position of its band gap (corresponding to the pi-pi* transition) by UV-Vis spectroscopy combined with cyclic voltammetry. These studies show that the polymer exhibits a slightly larger band gap with the HOMO level insignificantly lower in energy (by 0.03 eV) as compared to the case of regioregular poly(3-hexylthiophene) of comparable degree of polymerization. Hydrogen bond interactions of the polymer with CdSe(MHT) in the molecular composite result in a hypsochromic shift of the band corresponding to the pi-pi* transition from 504 nm to 488 nm. This can be taken as a spectroscopic manifestation of the conformational changes induced by shortening of the conjugation length. The observed spectral modifications are consistent with electrochemically determined lowering of the polymer HOMO level (from -4.91 eV in the pure polymer to -4.99 eV in the composite). Cyclic voltammetry studies supported by spectroelectrochemistry also show that the redox stability of CdSe(MHT) in the molecular composite with P3HT-co-P3(ODAP)HT is lower than that determined for stearate-capped nanocrystals. Their irreversible oxidation starts at E = +0.7 V vs. Ag/0.1 M Ag(+)i.e. at potentials by ca. 0.3 V lower than the oxidation of stearate stabilized CdSe nanocrystals of the same size. We show that-despite these modifications-the alignment of the HOMO and LUMO levels of the composite components remains appropriate for its use in hybrid solar cells, which is demonstrated by the photovoltaic effect observed for the LbL-processed composite sandwiched between two electrodes.     

Solution structure of R(2)Sn(IV)-beta-N-acetyl-neuraminate (R = Me, Bu) complexes in D(2)O and DMSO-d(6): experimental NMR and DFT computational study

Two diorganotin(IV)-NANA complexes (NANA (1) = beta-N-acetyl-Neuraminic Acid = 5-amino-3,5-dideoxy-D-glycero-beta-D-galactononulosic acid) with formula Me(2)Sn(iv)NANA (2) and Bu(2)Sn(IV)NANA (3) were synthesized and characterized by (1)H, (13)C and (119)Sn NMR spectroscopy, both in D(2)O and DMSO-d(6) solutions. The experimental data in DMSO suggested the monosaccharide bidentate chelation via O1 carboxylate and vicinal O2 alkoxide atoms, which, in D(2)O, can be dynamically extended to a third binding site (O8 atom) of the pendant chain. Coordination at the tin atom is discussed on the basis of experimental NMR data and DFT calculation.     

Convenient synthesis of pyrrolo[3,4-g]indazole

The synthesis of a novel class of tetrahydropyrrolo[3,4-g]indazoles is reported, by annelation of the pyrazole ring on the isoindole moiety by means of 5-hydroxymethylene tetrahydroisoindole-4-ones key intermediates, with good regioselectivity. Dihydroderivatives were also obtained by oxidation with DDQ of the corresponding tetrahydropyrrolo[3,4-g]indazoles. The growth inhibitory effect was evaluated at the National Cancer Institute of Bethesda and some derivatives showed modest activity.     

BOLD signal and vessel dynamics: a hierarchical cluster analysis

The aim of the present study was to analyze blood oxygenation level-dependent (BOLD) signal variation during an apnea-based task in order to assess the capability of a functional magnetic resonance imaging (fMRI) procedure to estimate cerebral vascular dynamic effects. We measured BOLD contrast by hierarchical cluster analysis in healthy subjects undergoing an fMRI experiment, in which the task paradigm was one phase of inspirational apnea (IA). By processing the time courses of the fMRI experiment, analysis was performed only on a subclass of all the possible signal patterns; basically, root mean square and absolute variation differences have been calculated. Considering the baseline value obtained by computing the mean value of the initial rest period as reference, particular voxels showed relative important variations during the IA task and during the recovery phase following the IA. We focused our interest on the signal response of voxels that would correspond mainly to white and gray matter regions and that also may be affected by the proximity of large venous vessels. The results are presented as maps of space-temporal distribution of time series variations with two levels of hierarchical clustering among voxels with low to high initial response. Furthermore, we have presented a clustering of the signal response delay, conducting to a partition and identification of specified brain sites.     

Metabolic alteration transients during paroxysmal activity in an epileptic patient with fixation-off sensitivity: a case study

The purpose of this study was to investigate short-time metabolic variations related to continuous epileptic activity elicited by fixation-off sensitivity (FOS). Time-resolved magnetic resonance spectroscopy was performed on a patient on whom previous clinical findings clearly indicated presence of FOS. The epileptic focus was localized with a simultaneous electroencephalographic and functional magnetic resonance imaging study. The results showed a linear increase of the sum of glutamate and glutamine with time of paroxysmal activity in epileptic focus and much greater concentration of choline-containing compounds in focus than in the contralateral side.     

Organic film thickness influence on the bias stress instability in?sexithiophene field effect transistors

In this paper, the dynamics of bias stress phenomenon in Sexithiophene (T6) Field Effect Transistors (FETs) has been investigated. T6 FETs have been fabricated by vacuum depositing films with thickness from 10 to 130 nm on Si/SiO₂ substrates. After the T6 film structural analysis by X-ray diffraction and the FET electrical investigation focused on carrier mobility evaluation, bias stress instability parameters have been estimated and discussed in the context of existing models. By increasing the film thickness, a clear correlation between the stress parameters and the structural properties of the organic layer has been highlighted. Conversely, the mobility values as a result are found to be almost thickness independent.