Générateurs de l'anneau des entiers d'une extension cyclotomique

Let p be an odd prime and q=pm, where m is a positive integer. Let ζq be a qth primitive root of 1 and Oq be the ring of integers in Q(ζq). In [I. Gaál, L. Robertson, Power integral bases in prime-power cyclotomic fields, J. Number Theory 120 (2006) 372-384] I. Gaál and L. Robertson show that if , where is the class number of , then if α∈Oq is a generator of Oq (in other words Z[α]=Oq) either α is equals to a conjugate of an integer translate of ζq or is an odd integer. In this paper we show that we can remove the hypothesis over . In other words we show that if α∈Oq is a generator of Oq then either α is a conjugate of an integer translate of ζq or is an odd integer.     

Spectromechanical Properties of Polymeric Gel Electrolytes and Blends

In this paper we studied the spectro-mechanical properties of polymer gel electrolytes and blends by means of shear rheology. These electrolytes were obtained by immobilizing EC/PC/LiClO₄ solutions in a polymeric matrix of PEO, PAN and PMMA, respectively. Two structural and thermoreversible transitions, a strong-to-weak gel and a gel-to-sol, were revealed and discussed. Moreover, PMMA-PVdF blends have been studied as a function of the different polymeric ratios in order to obtain the best compromise between ionic conduction and mechanical properties. Interesting mechanical properties were observed at some intermediate blend compositions.     

Complementary Approaches to Imaging Subcellular Lipid Architectures in Live Bacteria Using Phosphorescent Iridium Complexes and Raman Spectroscopy

A family of three neutral iridium(III) tetrazolato complexes are investigated as bacterial imaging agents. The complexes offer a facile tuning of the emission colour from green (520 nm) to red (600 nm) in aqueous media, while keeping the excitation wavelength unchanged. The three complexes do not inhibit the bacterial growth of Bacillus Cereus, used as a model in this study, and exhibit extremely fast cellular uptake. After a minute incubation time, the nontoxic complexes show subcellular localisation in spherical structures identified as lipid vacuoles. Confocal Raman imaging has been exploited for the first time on live bacteria, to provide direct and label-free mapping of the lipid-enriched organelles within B. cereus, complementing the use of luminescent probes. Examination of the Raman spectra not only confirmed the presence of lipophilic inclusions in B. cereus but offered additional information about their chemical composition, suggesting that the lipid vacuoles may contain polyhydroxybutyrate (PHB).     

Breathing Rhythm Variations during Wash-In Do Not Influence Exhaled Volatile Organic Compound Profile Analyzed by an Electronic Nose

E-noses are innovative tools used for exhaled volatile organic compound (VOC) analysis, which have shown their potential in several diseases. Before obtaining a full validation of these instruments in clinical settings, a number of methodological issues still have to be established. We aimed to assess whether variations in breathing rhythm during wash-in with VOC-filtered air before exhaled air collection reflect changes in the exhaled VOC profile when analyzed by an e-nose (Cyranose 320). We enrolled 20 normal subjects and randomly collected their exhaled breath at three different breathing rhythms during wash-in: (a) normal rhythm (respiratory rate (RR) between 12 and 18/min), (b) fast rhythm (RR > 25/min) and (c) slow rhythm (RR < 10/min). Exhaled breath was collected by a previously validated method (Dragonieri et al., J. Bras. Pneumol. 2016) and analyzed by the e-nose. Using principal component analysis (PCA), no significant variations in the exhaled VOC profile were shown among the three breathing rhythms. Subsequent linear discriminant analysis (LDA) confirmed the above findings, with a cross-validated accuracy of 45% (p = ns). We concluded that the exhaled VOC profile, analyzed by an e-nose, is not influenced by variations in breathing rhythm during wash-in.     

Patterning of Polymeric Hydrogels for Biomedical Applications

Surface‐patterned 2‐hydroxyethyl methacrylate hydrogels were produced by using a method similar to the silicon‐rubber stamp fabrication for microcontact printing. Polymerization and network formation were carried out in contact with a micromachined silicon wafer. The polymeric patterns retained their shape during isotropic swelling/deswelling cycles. The use of microstructured hydrogels in tissue engineering can be envisaged.     

The Experimental Observation of the Intramolecular NO2/CO Interaction in Solution

The weak electrostatic interaction between nitro and carbonyl moieties has been observed by means of variable‐temperature NMR spectroscopy. Its energetic contribution was evaluated to be about 3 kcal mol^?1 by DFT calculations, and confirmed by the measurement of internal energy barriers to the rotation of suitable nitroaryl rings.     

Exafs studies of LiYF 4 -LiREF 4 solid solutions

In this work we are investigating dopant environments in LiYF 4 -LiREF 4 (RE=rare-earth cations) solid solutions, via EXAFS. The main aims are to identify the local environmental symmetry and the average lattice distortion as a function of the concentration and the type of the RE ion. LiY 1 m x RE x F 4 (RE=Gd or Lu) (0< x <1) single crystals were grown by the Czochralski technique under argon or CF 4 atmosphere, crystal-pulling rates were 0.6-1 v mm/h for <100>-oriented boules, with 8-25 v rpm rotation rates. Most of the crystals were also codoped with 2.7 v mol% of neodymium in the melt. EXAFS measurements were performed in transmission and fluorescence modes in the synchrotron XAS line of the LNLS, Campinas, Brazil, in and above the L III absorption edges of the RE ions. The samples were prepared as powder films, for the transmission mode measurements, and as powder or single crystals for fluorescence mode measurements. The WINXAS program was used for data reduction and fitting, and the FEFF6 package was used for the simulations of the spectra. The EXAFS oscillation curves were obtained by standard procedure.     

Gelation of charged bio-nanocompartments induced by associative and non-associative polysaccharides

Vesicles composed of sodium oleate (NaO) and monoolein (MO) are adequate candidates for drug nanoencapsulation and controlled release due to their stability and perceived biocompatibility. The object of the present study is to design hydrogels based on those anionic vesicles and polymers of both non-associative and associative type. The selected macromolecules were k-carrageenan (KC), carboxymethyl cellulose (CMC) and hydrophobically modified carboxymethyl cellulose (HMCMC). While the polymer-vesicle association was probed by rheology, the influence of the polymer on the vesicle stability was monitored by cryo-TEM and calorimetric measurements. The effects of the polymer on the rheological properties of surfactant aggregate solutions clearly depend on the polymer type: the storage moduli of the polymer-vesicle mixtures, compared to the vesicles alone, increases around 2 orders of magnitude if the polymer is non-associative and 4 orders of magnitude if the macromolecule is of associative type. As the vesicles are added, the non-associative polymer networks tend to be disrupted, while the networks formed by associative polymer get more robust. These observations can be explained by fundamental changes in electrostatic/hydrophobic interactions: vesicles entrapped in KC networks convert the polysaccharide in a highly charged entity and favor high electrostatic repulsions between the chains; this encourages network collapse. The opposite picture is experienced in HMCMC systems, i.e., such network is stabilized by the presence of vesicles. This is ascribed to the enhanced hydrophobic association, compensating the electrostatic repulsions between vesicles and polymer chains.     

pH-Induced changes in adsorbed cytochrome c. voltammetric and surface-enhanced resonance Raman characterization performed simultaneously at chemically modified silver electrodes

The influence of pH on the redox properties of cytochrome c (cyt c) adsorbed on roughened silver electrodes chemically modified with a self-assembled monolayer (SAM) of 11-mercapto-1-undecanoic acid (MUA) was studied with voltammetric techniques in combination with surface-enhanced resonance Raman scattering (SERRS). The experiments were performed simultaneously on the same electrode sample in a homemade spectroelectrochemical cell suitable for such applications. At pH 7.0 cyt c was found in its native state; at higher pH values (ranging from 8.0 to 9.0) the redox properties of the adsorbed protein varied considerably, featuring a redox behavior which does not resemble the one reported for the alkaline transition. Our results instead indicate the presence of an electrochemically inactive 6cLS species immobilized on MUA at pH 9.0. The pH-induced conformational changes observed for cyt c immobilized on the SAM of MUA were found to be repeatable and chemically reversible, meaning that the recovery of the electrochemical signal due to the native protein occurred instantaneously (on the second time scale) when the electrode was switched back to pH 7.0. The pH-induced changes observed were attributed to a conformational change involving a heme reorientation with respect to the electrode surface.