Search results for " Glass"
showing 10 items of 409 documents
Watch glasses exposed to 6 MV photons and 10 MeV electrons analysed by means of ESR technique: A preliminary study
2011
Abstract In this work we report a case study of the ESR response of watch glasses exposed to 6 MV photons and to 10 MeV electrons. The choice of watch glasses is justified by the fact that watch glasses are very close to the exposed individual. For both types of radiation beams, the absorbed doses belong to the range between 1 and 20 Gy. The samples have been irradiated in water-equivalent plastic phantom with a linear accelerator used for radiotherapy. After exposure watch glass samples have been cut in small strip-shaped pieces with suitable size to be put into the quartz tube for ESR measurements. The signal induced by radiation (RIS) lies in the g ∼ 2 region and must be discriminated fr…
Structural modifications induced by electron irradiation in SiO2 glass: Local densification measurements
2009
We report a study on the structural modifications induced in amorphous silicon dioxide (a-SiO2) by electron irradiation in the dose range from 1.2?103 to 5?106?kGy. This study has been performed by investigating the properties of the 29Si hyperfine structure of the E '? center by electron paramagnetic resonance (EPR) spectroscopy. Our data suggest that the structural modifications induced by irradiation take place through the nucleation of confined high-defective and densified regions statistically dispersed into the whole volume of the material. In addition, we have estimated that in the high dose limit (D?105?kGy) the degree of densification associated to the local (within the defective r…
Absorption edge in silica glass
2005
Measurements of optical absorption in the v-UV range in a variety of silica glass are used to determine the width of the absorption edge (Urbach energy). Measured values range from 60 meV up to 180 meV. So high a variability over silica types is tentatively ascribed to the different disorder degree, which characterizes different materials.
Dichroic atomic vapor laser lock with multi-gigahertz stabilization range
2016
A dichroic atomic vapor laser lock (DAVLL) system exploiting buffer-gas-filled millimeter-scale vapor cells is presented. This system offers similar stability as achievable with conventional DAVLL system using bulk vapor cells, but has several important advantages. In addition to its compactness, it may provide continuous stabilization in a multi-gigahertz range around the optical transition. This range may be controlled either by changing the temperature of the vapor or by application of a buffer gas under an appropriate pressure. In particular, we experimentally demonstrate the ability of the system to lock the laser frequency between two hyperfine components of the $^{85}$Rb ground state…
JIMWLK evolution of the odderon
2016
We study the effects of a parity-odd "odderon" correlation in JIMWLK renormalization group evolution at high energy. Firstly we show that in the eikonal picture where the scattering is described by Wilson lines, one obtains a strict mathematical upper limit for the magnitude of the odderon amplitude compared to the parity even pomeron one. This limit increases with N_c, approaching infinity in the infinite N_c limit. We use a systematic extension of the Gaussian approximation including both 2- and 3-point correlations which enables us to close the system of equations even at finite N_c. In the large-N_c limit we recover an evolution equation derived earlier. By solving this equation numeric…
Micro-variazioni audiovisive e forma-processo. Analisi semiotica di Koyaanisqatsi di Reggio, Glass e Fricke
2014
Uno degli esiti più importanti del minimalismo storico è l'apertura alle altre arti. Il motivo di questo “contatto”, tra musica minimalista e arti audiovisive (cinema) e performative (teatro, danza, opera) è da ricercare nella struttura stessa della musica minimalista: i suoi specifici stilemi linguistici la rendono particolarmente adatta non solo a supportare immagini e situazioni narrative, ma a divenire vero principio organizzatore di essi, dettando ritmo, continuità, coerenza semantica. Ciò accade ad esempio nel film Koyaanisqatsi, creato a sei mani da Godfrey Reggio (regia), Philip Glass (musiche) e Ron Fricke (fotografia e riprese). Uscito nel 1982, Koyaanisqatsi suscitò l'attenzione …
Tecnologie e valori dello sguardo. Occhiali e discorsività
2021
What is that very special object in our daily lives that is a pair of spectacles all about? It accompanies us faithfully through every moment of the day, it crouches beside us when we do without, or it is stowed away in a bag, momentarily resting on a shelf. But it is always ready to come back and ride our noses and ears in order to perform its inalienable function to the best of its ability. Function? A notion as pernicious as it is indispensable when dealing with a sure design product such as spectacles. An unfortunate, polysemic, inflated term, problematised in a thousand ways; an intrusive and unwelcome guest, with whom one never ends up coming to terms. One sends him away and finds him…
BSA Aggregation in Trehalose-Water Systems
2010
Introduction Recent studies [1] on ternary protein-trehalose-water samples have shown that the protein thermal denaturation temperature is linearly correlated with the glass transition temperature of the system, despite the quite large temperature difference between the two processes. In such studies it is stated that the collective, long range properties of the matrix that regulate the glass transition are strictly correlated with local features on which the denaturation of the protein depends. In order to ascertain whether an analogous correlation exists between the effects of trehalose on the protein’s aggregation process and the glass transition temperature of the system, we performed L…
Bioactive glass ions induce efficient osteogenic differentiation of human adipose stem cells encapsulated in gellan gum and collagen type I hydrogels
2019
Abstract Background Due to unmet need for bone augmentation, our aim was to promote osteogenic differentiation of human adipose stem cells (hASCs) encapsulated in gellan gum (GG) or collagen type I (COL) hydrogels with bioactive glass (experimental glass 2-06 of composition [wt-%]: Na2O 12.1, K2O 14.0, CaO 19.8, P2O5 2.5, B2O3 1.6, SiO2 50.0) extract based osteogenic medium (BaG OM) for bone construct development. GG hydrogels were crosslinked with spermidine (GG-SPD) or BaG extract (GG-BaG). Methods Mechanical properties of cell-free GG-SPD, GG-BaG, and COL hydrogels were tested in osteogenic medium (OM) or BaG OM at 0, 14, and 21 d. Hydrogel embedded hASCs were cultured in OM or BaG OM fo…
A multichannel piezo driver for active mirrors in X-ray telescopes
2016
X-ray astronomy is gaining importance for studying X-ray space sources such as single and binary stars, neutron stars, supernovae and black holes. Due to atmospheric absorption, X-ray telescopes must operate in space on satellites. Among the causes limiting the resolution of modern telescopes are distortions in mirrors shape. An innovative approach for X-ray mirrors aims at correcting the shape errors by means of piezo-ceramic actuators glued to the back of the mirrors, thus creating an “active mirror”. In order to test the viability of shape correction, we fabricated [1] a prototype of a thin glass active mirror, sized 20 cm x 20 cm with a 400 um thickness (Fig. 1). The mirror can allocate…