Search results for "Helium"
showing 10 items of 1689 documents
Enhanced Permeability and Retention-like Extravasation of Nanoparticles from the Vasculature into Tuberculosis Granulomas in Zebrafish and Mouse Mode…
2018
The enhanced permeability and retention (EPR) effect is the only described mechanism enabling nanoparticles (NPs) flowing in blood to reach tumors by a passive targeting mechanism. Here, using the transparent zebrafish model infected with Mycobacterium marinum we show that an EPR-like process also occurs allowing different types of NPs to extravasate from the vasculature to reach granulomas that assemble during tuberculosis (TB) infection. PEGylated liposomes and other NP types cross endothelial barriers near infection sites within minutes after injection and accumulate close to granulomas. Although similar to 100 and 190 nm NPs concentrated most in granulomas, even similar to 700 nm liposo…
On the correlation between mechanical and TEM studies of the aging of palladium during tritium storage
2005
Abstract Tritium has considerable technological applications in nuclear industry. Since it is a radioactive element, its storage is often considered in the form of tritides which ensure the required safety. However, the decay of tritium into 3 He alters the tritide properties during aging. With the aim of understanding the aging mechanisms of palladium tritide, a macroscale approach coupled with a microscopic study was performed on palladium aged up to eight months after tritium loading. The macroscale investigation based on the vibration of microcantilevers allowed the mechanical response of the material to be followed during its aging. The microscopic study was performed by Transmission E…
Novel method for determination of tritium depth profiles in metallic samples
2019
Tritium accumulation in fusion reactor materials is considered a serious radiological issue, therefore a lot of effort has been concentrated on the development of radiometric techniques. A novel method, based on gradual dissolution, for the determination of the total tritium content and its depth profiles in metallic samples is demonstrated. This method allows for the measurement of tritium in metallic samples after their exposure to a hydrogen and tritium mixture, tritium containing plasma or after irradiation with neutrons resulting in tritium formation. In this method, successive layers of metal are removed using an appropriate etching agent in the controlled regime and the amount of evo…
Development of antennal sensilla during moulting inNeomysis integer (Leach) (Crustacea, Mysidacea)
1980
The sensilla are associated with 6 enveloping cells. The innermost enveloping cell (e 1) secretes the dendritic sheath (=thecogen cell). All other enveloping cells are involved in the formation of the outer cuticular apparatus in secreting the cuticle of a definite region of the new hair shaft. The development of the new sensilla begins when an exuvial space expands between old cuticle and epithelium. The newly forming hair shafts lie folded back in an invagination of the epidermal tissue. Only a distal shaft part projects into the free exuvial space. The cuticle of the distal and middle shaft region is secreted by the three middle enveloping cells (e 2–e 4) (=trichogen cells), which are ar…
Fabry Disease, a Complex Pathology Not Easy to Diagnose
2015
Fabry disease is a multisystemic lysosomal storage disorder, inherited in an X-linked manner. It is a defect of metabolism of the glycosphingolipids, due to the reduction or absence of the activity of lysosomal enzyme α-galactosidase A. This reduction of activity causes the storage of globotriaosylceramide and derivatives in the lysosomes, triggering a cascade of cellular events, mainly in vascular endothelium. These events are the responsible for the systemic clinical manifestations and the renal, cardiac and cerebrovascular complications, or a combination of them. The symptomatology can lead to the premature death of patient between the fourth or fifth decade of life. The first symptoms c…
Heat rectification in He II counterflow in radial geometries
2018
Abstract We consider heat rectification in radial flows of turbulent helium II, where heat flux is not described by Fourier's law, but by a more general law. This is different from previous analyses of heat rectification, based on such law. In our simplified analysis we show that the coupling between heat flux and the gradient of vortex line density plays a decisive role in such rectification. Such rectification will be low at low and high values of the heat rate, but it may exhibit a very high value at an intermediate value of the heat rate. In particular, for a given range of values for the incoming heat ow, the outgoing heat flow corresponding to the exchange of internal and external tem…
Growth of beryllium oxide nano-structures during thermal treatment of neutron irradiated beryllium
2015
Beryllium oxide nano-structures grown during high temperature oxidation of neutron irradiated beryllium has been investigated. Oxidation of non - irradiated and neutron irradiated beryllium was performed in differential thermal analyzer in an atmosphere of air and its mixture with helium at temperatures up to 1050°C. Structure of beryllium and its oxide was studied by the means of scanning electron microscopy. The growth of beryllium oxide nano-structures – “labyrinth type” layers and nano-rods on the inner surfaces of neutron irradiated beryllium were observed by means of Scanning Electron Microscopy. The size of the rods was 10-100 nm in diameter and up to few micrometers in length. There…
How cancer cells cross lymphatic endothelium?
2014
The lymphatic microcirculation is a key component of metastatic spread providing a pathway for cancer cell dissemination, and the endothelium seems to enhance or promote the invasiveness of certain cancer cells. Furthermore, some tumors secrete lymphangiogenic growth factors acting on the lymphatic vasculature to facilitate metastasis. This study, based on 875 ultrastructural serial sections and 9 three-dimensional reconstructions of 28 initial lymphatics, clarify the transmigration mechanism of cancer cells from the extravascular matrix to the lumen of initial lymphatics. The lymphatic identification and distribution were assessed by transmission electron microscopy and immunohistochemistr…
Elemental and isotope covariation of noble gases in mineral phases from Etnean volcanics erupted during 2001–2005, and genetic relation with peripher…
2008
Abstract During 2001–2005, Mount Etna was characterized by intense eruptive activity involving the emission of petrologically different products from several vents, which involved at least two types of magma with different degrees of evolution. We investigated the ratios and abundances for noble-gas isotopes in fluid inclusions trapped in olivines and pyroxenes in the erupted products. We confirm that olivine has the most efficient crystalline structure for preserving the pristine composition of entrapped gases, while pyroxene can suffer diffusive He loss. Both the minerals also experience noble gas air contamination after eruption. Helium isotopes of the products genetically linked to the …