Search results for "Ultra"

Definition of analytical cleaning procedures for archaeological pottery from underwater environments: The case study of samples from Baia (Naples, So…

2021

Abstract This work is focused on a multidisciplinary study of 13 pottery fragments collected in the submerged archaeological site of Baia (Naples, Italy). Founded by the Romans in the 1st century B.C., this archaeological area represents one of the greatest evidences of Roman architecture and it includes ancient ruins whose structures range from maritime villas and imperial buildings. Several diagnostic tests were carried out in order to characterize the archaeological materials, their structure and properties, as well as the alteration and degradation products. Degradation forms in seawater imply not only a variation in the physico-mechanical and chemical properties of the material but als…

FATIGUE LIFE ANALYSIS OF RAIL-WELDS USING LINEAR ELASTIC FRACTURE MECHANICS

2019

The initiation and growth of fatigue cracking is mainly due to high stress concentration, heterogeneity and poor quality of weld. The detection and rectification of such weld defects are major concerns of rail network managers to reduce potential risk of rail breaks and derailments. To estimate the fatigue life of welded joints and to analyze the progress of fatigue cracks, a fracture mechanics-based analysis and fatigue models were developed using Finite Element Analysis. The initial flaw is obtained from a sample weld using ultrasonic flaw detecting machine test. Linear Elastic Fracture Mechanics (LEFM) approach based on the Paris law was applied to determine critical crack size and the n…

Specific UV and VUV spectra light sources

1997

The report contains information about laboratory made radiofrequency powered electrodeless discharge sources (lamps) of resonance atomic spectra radiation for various elements (e.g. Hg, Cd, Zn, O, S, Se, Te, As, Sb, Bi, J, Br, Kr, Xe, H) having main spectral lines in UV and VUV region. There are known, and can be found a lot of new specific applications of such sources in laboratory made or commercial optical devices.

A theoretical study of the rotational structure of the ϵ(0,0) band of NO

2009

This study has been focused on the ϵ(0,0) band of the nitric oxide molecule, associated with the absorption electronic transition D2Σ+X 2Π, in the energetic vacuum ultraviolet region. A temperature of 295 K has been considered. The Molecular Quantum Defect Orbital (MQDO) methodology, with which reliable spectroscopic data have been reached in the γ(0,0), δ(0,0), and δ(1,0) bands of the same molecule, has also been used for these calculations. We hope that the present results might be of straightforward use in atmospheric and interstellar chemistry. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010

Spin-resolved low-energy and hard x-ray photoelectron spectroscopy of off-stoichiometric Co2MnSi Heusler thin films exhibiting a record TMR

2015

Half-metallic Co2MnSi-based Heusler compounds have attracted attention because they yield very high tunnelling magnetoresistance (TMR) ratios. Record TMR ratios of 1995% (at 4.2 K) are obtained from off-stoichiometric Co2MnSi-based magnetic tunnel junctions. This work reports on a combination of band structure calculations and spin-resolved and photon-polarisation-dependent photoelectron spectroscopy for off-stoichiometric Heusler thin films with the composition Co2Mn1.30Si0.84. Co and Mn are probed by magnetic dichroism in angle-resolved photoelectron spectroscopy at the 2p core level. In contrast to the delocalised Co 3d states, a pronounced localisation of the Mn 3d states is deduced fro…

Electronic structure of large disc-type donors and acceptors

2010

Searching for new pi-conjugated charge-transfer systems, the electronic structure of a new acceptor-donor pair derived from coronene (C(24)H(12)) was investigated by ultraviolet photoelectron spectroscopy (UPS). The acceptor coronene-hexaone (C(24)H(6)O(6), in the following abbreviated as COHON) and the donor hexamethoxycoronene (C(30)H(24)O(6), abbreviated as HMC) were adsorbed as pure and mixed phases on gold substrates. At low coverage, COHON adsorption leads to the appearance of a charge-transfer induced interface state 1.75 eV below the Fermi energy. At multilayer coverage the photoemission intensity of the interface state drops and the valence spectrum of neutral COHON appears. The sa…

Electronic structure of metal‐free phthalocyanine : A valence effective Hamiltonian theoretical study

1988

We present a valence effective Hamiltonian (VEH) nonempirical investigation of the electronic properties of metal‐free phthalocyanine. The valence one‐electron energy levels are related to those of the phthalocyanine components: benzene, pyrrole, and isoindole. From the electronic structure standpoint, phthalocyanine has to be viewed as formed by joining four benzene moieties to the central carbon–nitrogen ring rather than by combining four isoindole units through nitrogen bridges. Comparison of the VEH density‐of‐valence‐states curves with the experimental ultraviolet photoelectron spectroscopy (UPS) data is quantitatively excellent and allows for a complete interpretation of the experimen…

Natural optical anisotropy of h-BN: Highest giant birefringence in a bulk crystal through the mid-infrared to ultraviolet range

2018

The giant birefringence of layered h-BN was demonstrated by analyzing the interference patterns in reflectance and transmittance measurements in the mid-infrared to the deep ultraviolet energy range. The refractive index for polarization perpendicular to the c axis is much higher than the refractive index for polarization parallel to the c axis, and it displays a strong increase in the ultraviolet range that is attributed to the huge excitonic effects arising from the unique electronic structure of h-BN. Thus, h-BN is shown to exhibit a giant negative birefringence that ranges from -0.7 in the visible to -2 in the deep ultraviolet close to the band gap. The electronic dielectric constants f…

Capillary enlargement, not sprouting angiogenesis, determines beneficial therapeutic effects and side effects of angiogenic gene therapy.

2010

Aims Currently, it is still unclear which mechanisms drive metabolic benefits after angiogenic gene therapy. The side-effect profile of efficient angiogenic gene therapy is also currently incompletely understood. In this study, the effects of increasing doses of adenoviral (Ad) vascular endothelial growth factor-A (VEGF-A) were evaluated on vascular growth, metabolic benefits, and systemic side effects. Methods and results Adenoviral vascular endothelial growth factor-A or AdLacZ control was injected intramuscularly (109–1011 vp/mL) or intra-arterially (5 × 1011 vp/mL) into rabbit ( n = 102) hindlimb muscles and examined 6 or 14 days later. Blood flow, tissue oedema, metabolic benefits, and…

2021

Abstract Reliable patient-specific ventricular repolarization times (RTs) can identify regions of functional block or afterdepolarizations, indicating arrhythmogenic cardiac tissue and the risk of sudden cardiac death. Unipolar electrograms (UEs) record electric potentials, and the Wyatt method has been shown to be accurate for estimating RT from a UE. High-pass filtering is an important step in processing UEs, however, it is known to distort the T-wave phase of the UE, which may compromise the accuracy of the Wyatt method. The aim of this study was to examine the effects of high-pass filtering, and improve RT estimates derived from filtered UEs. We first generated a comprehensive set of UE…