Variational solution of the Gross-Neveu model; 2, finite-N and renormalization

We show how to perform systematically improvable variational calculations in the O(2N) Gross-Neveu model for generic N, in such a way that all infinities usually plaguing such calculations are accounted for in a way compatible with the renormalization group. The final point is a general framework for the calculation of non-perturbative quantities like condensates, masses, etc..., in an asymptotically free field theory. For the Gross-Neveu model, the numerical results obtained from a "two-loop" variational calculation are in very good agreement with exact quantities down to low values of N

DC conduction mechanism of some new lower rim substituted calixarenes derivatives in thin films

Date du colloque : 09/2014International audienc

Prophylactic heparin and risk of orotracheal intubation or death in patients with mild or moderate COVID-19 pneumonia

Prophylactic low molecular weight heparin (pLMWH) is currently recommended in COVID-19 to reduce the risk of coagulopathy. The aim of this study was to evaluate whether the antinflammatory effects of pLMWH could translate in lower rate of clinical progression in patients with COVID-19 pneumonia. Patients admitted to a COVID-hospital in Rome with SARS-CoV-2 infection and mild/moderate pneumonia were retrospectively evaluated. The primary endpoint was the time from hospital admission to orotracheal intubation/death (OTI/death). A total of 449 patients were included: 39% female, median age 63 (IQR, 50–77) years. The estimated probability of OTI/death for patients receiving pLMWH was: 9.5% (95% CI 3.2–26.4) by day 20 in those not receiving pLMWH vs. 10.4% (6.7–15.9) in those exposed to pLMWH; p-value = 0.144. This risk associated with the use of pLMWH appeared to vary by PaO_{2}/FiO_{2} ratio aHR 1.40 (95% CI 0.51–3.79) for patients with an admission PaO_{2}/FiO_{2} ≤ 300 mmHg and 0.27 (0.03–2.18) for those with PaO_{2}/FiO_{2} > 300 mmHg; p-value at interaction test 0.16. pLMWH does not seem to reduce the risk of OTI/death mild/moderate COVID-19 pneumonia, especially when respiratory function had already significantly deteriorated. Data from clinical trials comparing the effect of prophylactic vs. therapeutic dosage of LMWH at various stages of COVID-19 disease are needed

In vitro antifungal activity of some plant extracts against Fusarium oxysporum in blackcurrant (Ribes nigrum L.)

There were tested and screened, in vitro, nine plant extracts manufactured by Hofigal S.A., against Fusarium oxysporum (strain Fo 18) isolated from blackcurrant plants (Ribes nigrum L.). The highest in vitro activity (efficacy 78.6%) was recorded for Allium sativum extract, followed by Satureja hortensis and Valeriana officinalis extracts (71.4% efficacy), at 20% concentration. A good inhibitory activity on mycelial growth has been observed for Mentha sp., Rosmarinus officinalis, Hyssopus officinalis and Artemisia dracunculus ‘Sativa’ (62.8%, 58.6%, 57.1% and, respectively, 50% efficacy). Achillea millefolium extract had no effect on radial growth of F. oxysporum isolate. This report is the first in Romania regarding the in vitro antifungal activity of some plant extracts on F. oxysporum in blackcurrant. These data are very useful for plant protection practice, particularly for medicinal plants, as blackcurrant, which demands for non pollutant and environmental friendly alternative methods to fungicides. Locally plant extracts could have important roles in sustainable based management strategies of Fusarium disease in blackcurrant

Electron spin resonance spectroscopy investigations of carbon nanotubes - epoxy composites

Electron spin resonance investigations on carbon nanotubes-epoxy composites containing 1%, 2%, and 3% multiwalled nanotubes with a length of 10 pm are reported. The observed resonance spectrum is dominated by a strong line with a peak to peak width of about 14 Gauss, located at g=2.023, and characterized by a negligible asymmetry. It was found that the resonance line position (g factor), resonance line width, and double integral of the resonance line are essentially temperature independent in the range 150 K - 250 K. This resonance line was assigned to uncoupled electronic spins delocalized over carbon nanotubes

UV irradiation influence on the structural and optical properties of CdO thin films

Polycrystalline Cd thin films were evaporated in a vacuum onto glass substrates at Cd source temperature of 770 K. The as-deposited Cd films were subjected to a gradual heating at the rate of 5 K/min, up to a temperature of 650 K and were then maintained at this temperature for 5 min. Then, the respective samples were cooled down to room temperature at the same rate. The obtained CdO thin films were UV irradiated for 2 h (150 W mercury lamp, 3.18–3.65 eV). By means of XRD, AFM and XPS techniques, the structural characteristics of the typical obtained CdO samples before and after UV treatment were investigated. The obtained results indicate that the UV treatment induces a recrystallization process: changes in sample morphology, surface roughness and crystallite size and orientation. XRD and XPS studies evidenced an improvement in crystalline structure and stoichiometry. UV irradiated sample shows photo-catalytic properties

Electrical conduction properties of Co-doped ZnO nanocrystalline thin films

WOS: 000300317500015The temperature dependent conductivity behavior of 15% Co and 25% Co-doped ZnO nanocrystalline thin films prepared by spin-coating method was examined. It was found that the conductivity shows a change when the Co concentration varies from 15 to 25%. The observed increase of conductivity with increasing Co concentration was interpreted through the grain boundary conduction model. The temperature dependent conductivity of the films was analyzed in term of formulas in consistence with grain boundary conduction model. With rising temperature for 25% Co doped ZnO, a transition from the region in which crystallites are only partially depleted to the region in which the crystallites are entirely depleted was observed around 375 K. Some improtant electrical parameters were determined for the films.[POSDRU/89/1.5/S/49944]; [PN II 12-128/2008 ELOTRANSP]We are thankful to dr. V. Nica for carrying out XRD measurements. This work was supported by the research projects POSDRU/89/1.5/S/49944 and PN II 12-128/2008 ELOTRANSP

Ni doping effect on electrical conductivity of ZnO nanocrystalline thin films

WOS: 000293773500047The electrical conductivity behavior of undoped and Ni-doped ZnO nanocrystalline thin films prepared by spin-coating method was investigated as a function of temperature. The films were found to have polycrystalline structure. Grain size and the conductivity of the films were found to decrease significantly with increase in Ni concentration. This behavior was well explained by the grain boundary conduction model that takes into account electron trapping in surface states. It was observed that by increasing the Ni-doping level the surface trap density increases and implicitly the conductivity decreases.[POSDRU/89/1.5/S/49944]; [PN II 12-128/2008 ELOTRANSP]We are thankful to B.F. Oprea for carrying out XPS measurements. This work was supported by the research projects POSDRU/89/1.5/S/49944 and PN II 12-128/2008 ELOTRANSP