Search results for "Helium"
showing 10 items of 1689 documents
A luminal glycoprotein drives dose-dependent diameter expansion of the Drosophila melanogaster hindgut tube
2012
An important step in epithelial organ development is size maturation of the organ lumen to attain correct dimensions. Here we show that the regulated expression of Tenectin (Tnc) is critical to shape the Drosophila melanogaster hindgut tube. Tnc is a secreted protein that fills the embryonic hindgut lumen during tube diameter expansion. Inside the lumen, Tnc contributes to detectable O-Glycans and forms a dense striated matrix. Loss of tnc causes a narrow hindgut tube, while Tnc over-expression drives tube dilation in a dose-dependent manner. Cellular analyses show that luminal accumulation of Tnc causes an increase in inner and outer tube diameter, and cell flattening within the tube wall,…
Glaucomatous Maculopathy: Thickness Differences on Inner and Outer Macular Layers between Ocular Hypertension and Early Primary Open-Angle Glaucoma U…
2020
The purpose of this study was to compare the thickness of all inner and outer macular layers between ocular hypertension (OHT) and early primary open-angle glaucoma (POAG) using spectral domain optical coherence tomography (SD-OCT) 8 × 8 posterior pole algorithm (8 × 8 PPA). Fifty-seven eyes of 57 OHT individuals and fifty-seven eyes of 57 early POAG patients were included. The thickness of macular retinal nerve fiber layer (mRNFL), ganglion cell layer (GCL), inner plexiform layer (IPL), inner nuclear layer (INL), outer plexiform and nuclear layer, photoreceptor layer (PRL) and retinal pigment epithelium were obtained in 64 cells for each macular layer and mean thickness of superior and inf…
3He/4He Ratio in Olivines from Linosa, Ustica, and Pantelleria Islands (Southern Italy)
2011
We report helium isotope data for 0.03–1Ma olivine-bearing basaltic hawaiites from three volcanoes of the southern Italy magmatic province (Ustica, Pantelleria, and Linosa Islands). Homogenous 3He/4He ratios (range: 7.3–7.6 Ra) for the three islands, and their similarity with the ratio of modern volcanic gases on Pantelleria, indicate a common magmatic end-member. In particular, Ustica (7.6 ± 0.2Ra) clearly differs from the nearby Aeolian Islands Arc volcanism, despite its location on the Tyrrhenian side of the plate boundary. Although limited in size, our data set complements the large existing database for helium isotope in southern Italy and adds further constraints upon the spatial exte…
A PTFE membrane for the in situ extraction of dissolved gases in natural waters: Theory and applications
2005
A new method for extracting dissolved gases in natural waters has been developed and tested, both in the laboratory and in the field. The sampling device consists of a polytetrafluroethylene (PTFE) tube (waterproof and gas permeable) sealed at one end and connected to a glass sample holder at the other end. The device is pre-evacuated and subsequently dipped in water, where the dissolved gases permeate through the PTFE tube until the pressure inside the system reaches equilibrium. A theoretical model describing the time variation in partial gas pressure inside a sampling device has been elaborated, combining the mass balance and "Solution-Diffusion Model" (which describes the gas permeation…
Diagnostics of a charge breeder electron cyclotron resonance ion source helium plasma with the injection of 23 Na 1+ ions
2016
This work describes the utilization of an injected 23Na1þ ion beam as a diagnostics of the helium plasma of a charge breeder electron cyclotron resonance ion source. The obtained data allows estimating the upper limit for the ion-ion collision mean-free path of the incident sodium ions, the lower limit of ion-ion collision frequencies for all charge states of the sodium ions and the lower limit of the helium plasma density. The ion-ion collision frequencies of high charge state ions are shown to be at least on the order of 1–10 MHz and the plasma density is estimated to be on the order of 1011 cm−3 or higher. The experimental results are compared to simulations of the 23Na1þ capture into th…
Deep-sourced fluids released in central-western Europe: new evidences of active degassing in Serbia region
2021
Identification of transfer of mantle-derived fluids (e.g. CO2, N2, noble gases) in continental regions is critical for developing exploration strategies of natural resources (i.e., hydrocarbons, ore deposits, heat sources) and also to investigate the processes that control the deep and shallow evolution of Earth such as subduction, volcanism, natural degassing vs. active tectonic and earthquakes (e.g., O’Nions & Oxburgh, 1988; Caracausi et al., 2013; Labidi et al., 2020). Recently the outgassing of deep-mantle volatiles has been verified in different crustal segments of central-western Europe, but the geological and tectonic controls on migration of these deep fluids remain to be fully …
Mantle-derived fluids in Central Mediterranean: Geochemical and geophysical constrains on sources of fluids and migration
2013
The geodynamics of the central Mediterranean is characterized by the interaction between the European plate and the African’s. In this setting Sicily is a sector of the Appenine-Maghrebide accretionary prism, which is located between two areas affected by extensional tectonics (Sicily Channel to the south and the Thyrrenian back arc basin to the north). Significant mantle-derived helium (0.4<R/Ra<2.8; R=3He/4He in the sample, Ra in atmosphere) is found in the CH4 and N2-CO2 rich fluids released in central western Sicily, a region without evidence of recent magmatism. CH4- dominated gases are released from mud volcanoes localized in an area of both low heat flow and seismicity. On the contra…
Minimum detection limits and applications of proton and helium induced X-ray emission using transition-edge sensor array
2017
Abstract We have determined minimum detection limits, MDLs, for elements 14 ⩽ Z ⩽ 86 using a transition-edge sensor array, TES array, and as a comparison using an Amptek X-123SDD silicon drift detector, SDD. This was done using a 3 MeV proton beam and a 5.1 MeV helium beam. MDLs were determined for a thin film sample on top of C substrate, and for a bulk sample containing mostly Al. Due to the higher peak-to-background ratio, lower detection limits were obtainable using the TES array for most of the elements. However, for elements 30 ⩽ Z ⩽ 45 the performance of the TES array was not as good as the SDD performance. This is due to the limitations of the TES used at energies >10 keV. The great…
Endothelial cells loss to the hyperopic pacients during phacoemulsification
2018
Introduction The phacoemulsification cataract surgery is the most frequently performed surgery and it generally improves vision in over 90% of the patients. Hyperopic patients are a challenge during phacoemulsification especially because of their short eyeball and shallow anterior chamber. A shallow anterior chamber is associated with overall reduction of the safe zone, which may lead to difficulty in creating the corneal incisions, harder capsulorhexis performing, or endothelial complications. Purpose The aim of the study was to present the endothelial cells loss after the phacoemulsification procedure in the hyperopic patients. Material and methods A number of 1775 patients operated in th…
NG-monomethyl-L-arginine and NG-nitro-L-arginine inhibit endothelium-dependent relaxations in human isolated omental arteries.
1991
Abstract The L-arginine analogues NG-monomethyl-l-arginine (l-NMMA, 10−4 m) and NG-nitro-L-arginine methyl ester (l-NAME, 10−4 m), which specifically inhibit the synthesis of nitric oxide from l-arginine, significantly reduced acetylcholine-induced endothelium-dependent relaxations in rings of human omental arteries. The inhibitory potency of l-NMMA and l-NAME was similar. Addition of l-NMMA or l-NAME to the organ bath did not induce any significant changes in the resting tension of the tissues. The effects of l-NMMA were reversed by l-arginine (3 × 10−4 m). The l-NMMA enantiomer, d-NMMA (10−4 m), did not influence either the basal tone of the preparation or the relaxing effects of acet…