138 research outputs found

    The application of soil gas technique to geothermal exploration:

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    Geochemical studies were conducted throughout soil gas and flux surveying for locating both permeable zones in buried reservoirs and the presence of possible gaseous haloes linked to active geothermal systems. In this work we focused our interest on the distribution of soil gas concentrations (Rn, Th, He, H2, O2, N2, CO2, CH4 and H2S) in the soil air of the Tetitlan area considered a potential thermal field and characterized by scarcity of surface manifestations. Radon is used as a tracer gas to provide a qualitative idea of gas transfer (velocity and flux), carbon dioxide and methane are believed to act as carriers for other gases (i.e., Rn and He), helium and hydrogen are used as shallow signals of crustal leaks along faults (Ciotoli et al., 2005). Methane is also considered both a characteristic biogenic indicator of organic matter deposits and a tracer of major crustal discontinuity. A total of 154 soil gas samples were collected in an area of about 80 square kilometres. The same area was investigated throughout a total of 346 of CO2 and CH4 flux measurements

    The application of soil gas technique to geothermal exploration:study of “hidden” potential geothermal systems

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    Geochemical studies were conducted using soil-gas and flux surveyings for locating both permeable zones in buried reservoirs and the presence of possible gaseous haloes linked to active geothermal systems. In this work we focused our interest on the distribution of soil-gas concentrations (Rn, Th, He, H2, O2, N2, CO2, CH4 and H2S) in the soil air of the Tetitlan area (Nayarit, Mexico) considered a potential thermal field and characterized by scarcity of surface manifestations. A total of 154 soil-gas samples and 346 CO2 and CH4 flux measurements were collected in an area of about 80 square kilometres. The performed soil-gas and flux geochemical surveys highlighted a general rising patterns linked to local fault system, with the important implication that the highest CO2 and CH4 fluxes, as well as Rn concentrations, could be used in undeveloped geothermal systems to identify main upflow regions and areas of increased and deep permeability

    Concomitant dehiscences of the temporal bone: a case-based study

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    Otic capsule dehiscences create a pathological third window in the inner ear that results in a dissipation of the acoustic energy consequent to the lowered impedance. Superior semicircular canal dehiscence (SSCD) was identified by Minor et al. in 1998 as a syndrome leading to vertigo and inner ear conductive hearing loss. The authors reported the relation between the dehiscence and pressure- or sound-induced vertigo (Tullio phenomenon). The pathophysiology of this entity still remains controversial. Prevalence rates of SSCD in anatomical studies range from 0.4 to 0.7 % with a majority of patients being asymptomatic. The observed association with other temporal bone dehiscences, as well as the propensity toward a bilateral or contralateral near-dehiscence, raises the question of whether a specific local bone demineralization or systemic mechanisms could be considered. The present report regards a case of a patient with a previous episode of meningitis, with a concomitant bilateral SSCD and tegmen tympani dehiscence from the side of meningitis. The patient was affected by dizziness, left moderate conductive hearing loss and pressure/sound-induced vertigo. Because of disabling vestibular symptoms, the patient underwent surgical treatment. A middle cranial fossa approach allowed to reach both dehiscences on the symptomatic side, where bone wax and fascia were used. At 6 months from the procedure, hearing was preserved and the vestibular symptoms disappeared

    Epigallocatechin-3-gallate Delivered in Nanoparticles Increases Cytotoxicity in Three Breast Carcinoma Cell Lines

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    The anticancer act i v i t y of epigallocatechin-3-gallate (EGCG), orally administrated, is limited by poor bioavailabi l i t y , absorption, and unpredictable distribution in human tissues. EGCG charged nanoparticles may represent an opportunity to overcome these limitations. We assayed two different kinds of lipid nanoparticles (LNPs and LNPs functionalized with folic acid) charged with EGCG on three breast carcinoma cell lines (MCF-7, MDA-MB-231, and MCF-7TAM) and the human normal MCF10A mammary epithelial cells. Both LNPs loaded with EGCG, at low concentrations, induced a significant cytotoxicity in the three breast carcinoma cells but not in MCF10A cells. In view of a future application, both LNPs and LNPs-FA were found to be very suitable for in vitro studies and usef u l to improve EGCG administration in vivo. Since they are produced by inexpensive procedures using bioavailable, biocompatible, and biodegradable molecules, t h e y represent an applicable tool for a more rationale use of EGCG as an anti-cancer agent

    Identification by Virtual Screening and In Vitro Testing of Human DOPA Decarboxylase Inhibitors

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    Dopa decarboxylase (DDC), a pyridoxal 5′-phosphate (PLP) enzyme responsible for the biosynthesis of dopamine and serotonin, is involved in Parkinson's disease (PD). PD is a neurodegenerative disease mainly due to a progressive loss of dopamine-producing cells in the midbrain. Co-administration of L-Dopa with peripheral DDC inhibitors (carbidopa or benserazide) is the most effective symptomatic treatment for PD. Although carbidopa and trihydroxybenzylhydrazine (the in vivo hydrolysis product of benserazide) are both powerful irreversible DDC inhibitors, they are not selective because they irreversibly bind to free PLP and PLP-enzymes, thus inducing diverse side effects. Therefore, the main goals of this study were (a) to use virtual screening to identify potential human DDC inhibitors and (b) to evaluate the reliability of our virtual-screening (VS) protocol by experimentally testing the “in vitro” activity of selected molecules. Starting from the crystal structure of the DDC-carbidopa complex, a new VS protocol, integrating pharmacophore searches and molecular docking, was developed. Analysis of 15 selected compounds, obtained by filtering the public ZINC database, yielded two molecules that bind to the active site of human DDC and behave as competitive inhibitors with Ki values ≥10 µM. By performing in silico similarity search on the latter compounds followed by a substructure search using the core of the most active compound we identified several competitive inhibitors of human DDC with Ki values in the low micromolar range, unable to bind free PLP, and predicted to not cross the blood-brain barrier. The most potent inhibitor with a Ki value of 500 nM represents a new lead compound, targeting human DDC, that may be the basis for lead optimization in the development of new DDC inhibitors. To our knowledge, a similar approach has not been reported yet in the field of DDC inhibitors discovery

    Can Directional Resonances Be Used to Map Intensely Deformed Fault Zones of Mt. Etna Volcano ?

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    Mt. Etna is characterized by flank instability of the eastern to south-western portions of the volcanic edifice, producing down-slope movements with rates up to several decimeters in a month during eruptive events of the 2002-2003 activity. The unstable sector is bounded to the North by a E-W transtensive fault (the Pernicana fault system), extending from the NE Rift to the coastline of the Ionian Sea for a length of >18 km. The western portion of the Pernicana fault system (close to Piano Pernicana area) is characterized by the most intense deformation. In this area we have performed volcanic tremor measurements on a dense grid along and across the fault zone. Ambient vibration measurements are also performed along a second fault (Tremestieri fault) which confines the slip of the eastern flank to the south-east. The analysis using both microtremors and local earthquakes recorded in these faults shows persistent polarization of ground motion. Horizontal-to-vertical spectral ratios (HVSR) show large directional resonances of horizontal components within the damaged fault zones. The resonance occurs around 1Hz at Piano Pernicana, and around 4 Hz in the Tremestieri fault zone. The resonance amplitude in the HVSRs seems to be fairly well correlated to soil gas anomalous concentrations (in particular, radon and CO2 both considered tracer gases of major crustal discontinuity) in the two fault zones, suggesting that both the effects are linked to local fracturing conditions. According to previous results on velocity anisotropy in the shallow crust, we believe that a role on polarization could be played by stress-induced anisotropy and micro-fracture orientation in the near-surface lavas. The occurrence of directional resonances, if confirmed in other faults, can be a powerful tool to map buried damaged fault zones on the Mt. Etna volcano
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