Full characterization of the quantum linear-zigzag transition in atomic chains

A string of repulsively interacting particles exhibits a phase transition to a zigzag structure, by reducing the transverse trap potential or the interparticle distance. The transition is driven by transverse, short wavelength vibrational modes. Based on the emergent symmetry Z_2 it has been argued that this instability is a quantum phase transition, which can be mapped to an Ising model in transverse field. We perform an extensive Density Matrix Renormalization Group analysis of the behaviour at criticality and evaluate the critical exponents and the central charge with high precision. We thus provide strong numerical evidence confirming that the quantum linear-zigzag transition belongs to the critical Ising model universality class. These results show that structural instabilities of one-dimensional interacting atomic arrays can simulate quantum critical phenomena typical of ferromagnetic systems.Comment: 5 pages, 4 figure

A Novel Method for the Quantification of White Wine Mannoproteins by a Competitive Indirect Enzyme-Linked Lectin Sorbent Assay (CI-ELLSA)

Mannoproteins (MPs) are cell wall proteoglycans released in wine by yeast during fermentation and ageing on lees, a procedure used for the production of several wines to enrich them in these components with consequences from both a technological and sensory point of view. Given the significance that wine MPs have for wine quality, winemakers would welcome a simple and accurate method for their quantification, as this would allow them to have a better control of this aspect at different winemaking stages. This study develops and validates a novel, simple and accurate method for MPs quantification in white wines based on a competitive indirect enzyme-linked lectin sorbent assay (CI-ELLSA), using the highly mannosylated yeast invertase as the standard. The method utilizes the lectin concanavalin A (ConA) as the immobilized ligand for MPs, and peroxidase, an enzyme rich in mannose, as the competitor for ConA. After addition of the peroxidase substrate, the intensity of the signal produced by the activity of this enzyme (absorbance at 450 nm) is inversely proportional to the amount of mannosylated proteins in the sample. Results have been validated on several wine styles including still, sparkling and sweet wines

Micro-imaging VIS-IR spectroscopy of Martian meteorites in support of the future MaMIss spectrometer measurements

In the view of the future ExoMars 2020 mission, an activity of VIS-IR spectral investigations on terrestrial and extraterrestrial Mars Analogues is ongoing, in support of the Ma Miss in situ measurements. Ma_Miss is an imaging spectrometer that works in the range 0.4-2.2 μm with 20nm spectral sampling and that will observe the lateral wall of the borehole generated by ExoMars Rover's drill (Coradini et al., 2001). In this abstract, we describe some results about the spectral properties and characterization of mineral grains of the slabs of two Martian meteorites by means of the SPIM imaging spectrometer. SPIM works in the 0.22-5.05 μm spectral range, with a spatial resolution of 38x38 μm on the sample and represents the spare of the spectrometer on Dawn spacecraft (De Angelis et al., 2015). The meteorites investigated are North West Africa 8657 (NWA8657) and Dar Al Gani 489 (DAG489), basaltic shergottites. The average spectrum of the NWA8657 slab, in comparison with spectral measurements on other martian meteorites (Mcfadden & Cline, 2005) shows low reflectance values and 1 and 2 μm spectral absorptions indicating the strong presence of Ca-pyroxenes. The successive pixel by pixel analyses for the pyroxenes spectral speciation showed a great variability of clinopyroxenes in NWA8657. In fact, the 2 μm absorption at longer wavelength in some pixel does not always correspond to the 1 μm feature at longer wavelength. The average spectrum of DAG 489 is marked by a signature typical of low-Ca pyroxenes. Pixel by pixel analyses of DAG489 shows a more homogeneous composition of the pyroxenes characterized by the two major features centered at 0.98-0.99 and 1.98-2 μm. Further spectral absorptions related to sulfates, phosphates and carbonates were detected that are being validated by SEM-BSD to constrain the formation hystories of these two shergottites

Smoking Cessation in Mice Does Not Switch off Persistent Lung Inflammation and Does Not Restore the Expression of HDAC2 and SIRT1

Once COPD is established, pulmonary lesions can only progress and smoking cessation by itself is not sufficient to switch off persistent lung inflammation. Similarly, in former-smoker mice, neutrophil inflammation persists and lung lesions undergo progressive deterioration. The molecular mechanisms underlying disease progression and the inefficiency of smoking cessation in quenching neutrophilic inflammation were studied in male C57 Bl/6 mice after 6 months of rest from smoking cessation. As compared with the mice that continued to smoke, the former-smoker mice showed reduced expression of histone deacetylases HDAC2 and SIRT1 and marked expression of p-p38 MAPK and p-Ser10. All these factors are involved in corticosteroid insensitivity and in perpetuating inflammation. Former-smoker mice do show persistent lung neutrophilic influx and a high number of macrophages which account for the intense staining in the alveolar structures of neutrophil elastase and MMP-9 (capable of destroying lung scaffolding) and 8-OHdG (marker of oxidative stress). "Alarmins" released from necrotic cells together with these factors can sustain and perpetuate inflammation after smoking cessation. Several factors and mechanisms all together are involved in sustaining and perpetuating inflammation in former-smoker mice. This study suggests that a better control of COPD in humans may be achieved by precise targeting of the various molecular mechanisms associated with different phenotypes of disease by using a cocktail of drug active toward specific molecules

NO scavenging through reductive nitrosylation of ferric Mycobacterium tuberculosis and Homo sapiens nitrobindins

Ferric nitrobindins (Nbs) selectively bind NO and catalyze the conversion of peroxynitrite to nitrate. In this study, we show that NO scavenging occurs through the reductive nitrosylation of ferric Mycobacterium tuberculosis and Homo sapiens nitrobindins (Mt-Nb(III) and Hs-Nb(III), respectively). The conversion of Mt-Nb(III) and Hs-Nb(III) to Mt-Nb(II)-NO and Hs-Nb(II)-NO, respectively, is a monophasic process, suggesting that over the explored NO concentration range (between 2.5 × 10-5 and 1.0 × 10-3 M), NO binding is lost in the mixing time (i.e., NOkon ≥ 1.0 × 106 M-1 s-1). The pseudo-first-order rate constant for the reductive nitrosylation of Mt-Nb(III) and Hs-Nb(III) (i.e., k) is not linearly dependent on the NO concentration but tends to level off, with a rate-limiting step (i.e., klim) whose values increase linearly with [OH-]. This indicates that the conversion of Mt-Nb(III) and Hs-Nb(III) to Mt-Nb(II)-NO and Hs-Nb(II)-NO, respectively, is limited by the OH--based catalysis. From the dependence of klim on [OH-], the values of the second-order rate constant kOH- for the reductive nitrosylation of Mt-Nb(III)-NO and Hs-Nb(III)-NO were obtained (4.9 (±0.5) × 103 M-1 s-1 and 6.9 (±0.8) × 103 M-1 s-1, respectively). This process leads to the inactivation of two NO molecules: one being converted to HNO2 and another being tightly bound to the ferrous heme-Fe(II) atom

Anaesthetics modulate tumour necrosis factor α: effects of L-carnitine supplementation in surgical patients. Preliminary results.

Both anaesthetics and surgical trauma could strongly affect the production of tumour necrosis factor α (TNFα). During in vitro experiments the authors found that anaesthetics modulate the production of TNFα by peripheral blood mononuclear cells. Notably, Pentothal strongly increased the production of the cytokine as compared to both lipopolysacchride treated and control mononuclear cells, whereas in supernatants from Leptofen driven mononuclear cells TNFα was strongly reduced. On the other hand, Pavulon did not significantly affect the cytokine production. In the in vivo study, in an attempt to ameliorate the metabolic response to surgical trauma, L-carnitine was administered to 20 surgical patients, then the circulating TNFα was measured. The results indicate that the levels of circulating TNFα were strongly increased following surgery and that L-carnitine administration resulted in a strong reduction of TNFα. Thus, the data suggest that L-carnitine could be helpful in protecting surgical patients against dysmetabolism dependent on dysregulated production of TNFα

Sensibilidade in vitro de dermatófitos à uréia

OBJECTIVE: Urea is commonly used as a keratolytic substance in the treatment of onychomycoses to improve the penetration of antifungal drugs in the lesion sites. The aim of the present study was to investigate the inhibitory action of urea on samples of dermatophytes in vitro. METHOD: Minimum inhibitory concentration of urea was determined for 31 samples of dermatophytes cultured in Sabouraud-dextrose broth containing different concentrations (7.5% up to 40%) of urea. Absence of growth was the criterion adopted to determine the minimum inhibitory concentration. RESULTS: The majority of samples (87%) were sensitive to urea at 12.5%, or less. 2 isolates of Trichophyton tonsurans and 2 of Trichophyton rubrum required 30%, and 40% urea, respectively, to be completely inhibited. CONCLUSION: In vitro results demonstrate inhibitory activity of urea on dermatophytes, suggesting that it could be used as an adjuvant in topical treatments.OBJETIVO: A uréia é comumente usada como substância queratolítica no tratamento das onicomicoses no intuito de melhorar a penetração das drogas antifúngicas. O objetivo deste estudo foi investigar a ação inibitória in vitro da uréia em amostras de dermatófitos MÉTODOS: A concentração inibitória mínima da uréia foi determinada para trinta e uma amostras de dermatófitos semeadas em meio de cultura Sabouraud-dextrose contendo diferentes concentrações (7,5% até 40%) de uréia. Ausência de crescimento foi o critério adotado para a determinação da concentração inibitória mínima. RESULTADOS: A maioria das amostras (87%) foi sensível à uréia em concentrações de 12,5% ou menos. Apenas dois isolados de Trichophyton tonsurans e dois de Trichophyton rubrum foram inibidos completamente na presença de 30% e 40% de uréia, respectivamente. CONCLUSÃO: Os resultados in vitro demonstraram atividade inibitória da uréia sobre os dermatófitos, sugerindo que possa ser usada como um adjuvante em tratamentos tópicos