Search results for "DAMAGE"
showing 10 items of 1289 documents
Genotoxicity investigations on nanomaterials: methods, preparation and characterization of test material, potential artifacts and limitations--many q…
2008
Nanomaterials display novel properties to which most toxicologists have not consciously been exposed before the advent of their practical use. The same properties, small size and particular shape, large surface area and surface activity, which make nanomaterials attractive in many applications, may contribute to their toxicological profile. This review describes what is known about genotoxicity investigations on nanomaterials published in the openly available scientific literature to-date. The most frequently used test was the Comet assay: 19 studies, 14 with positive outcome. The second most frequently used test was the micronucleus test: 14 studies, 12 of them with positive outcome. The A…
A hybrid virtual–boundary element formulation for heterogeneous materials
2021
Abstract In this work, a hybrid formulation based on the conjoined use of the recently developed Virtual Element Method (VEM) and the Boundary Element Method (BEM) is proposed for the effective computational analysis of multi-region domains, representative of heterogeneous materials. VEM has been recently developed as a generalisation of the Finite Element Method (FEM) and it allows the straightforward employment of elements of general polygonal shape, maintaining a high level of accuracy. For its inherent features, it allows the use of meshes of general topology, including non-convex elements. On the other hand, BEM is an effective technique for the numerical solution of sets of boundary i…
Seismic Performance of Earthquake-Resilient RC Frames Made with HSTC Beams and Friction Damper Devices
2021
Seismic behavior of RC frames with hybrid steel-trussed concrete beams is affected by panel zone damage due to a large amount of longitudinal reinforcement. Here the seismic efficiency of innovative frames characterized by friction damper devices (FDDs) at beam-to-column connections is compared against traditional frame. Three configurations are investigated: FDDs alone; FDDs with column-to-foundation connections having preloaded threaded bars and disk springs; FDDs with self-centering friction devices. Non-linear analyses show that FDDs alone prevent plastic hinge formation at beam ends and beam–column joint damage. FDDs with self-centering friction devices effectively limit both peak and …
Computer modelling of radiation damage in cation sublattice of corundum
1998
Results of quantum chemical computer simulations of close Frenkel defects in corundum crystals are presented and discussed. The conclusion is drawn that the energy barrier for a back recombination up to fourth nearest neighbours is less than 0.3 eV, i.e. such pairs should be unstable at temperatures above 40 K.
Congenital reduction in number of nephrons accelerates renal damage, and limits proximal tubular growth response to release of neonatal partial urete…
2012
Aim: to analyze the evolution of the response to persistent partial ureteral obstruction (PUO) and obstruction/release (PUO/Rel) in mice with 50% reduction in the number of nephrons from 21 days of age (time of weaning) to 42 days of age (adulthood). Methods: C57/BL6 wild-type (WT) and mice with oligosyndactylism and 50% reduction of nephron number (Os/+), were subjected to sham operation or PUO in the first 2 days of life. Additional mice underwent release of obstruction at 7 days (PUO-Rel). The study was performed in kidneys harvested at 21 and 42 days. Using histomorphometry, glomerular area (GA) was determined by PAS staining, and fractional proximal tubular (PT) mass and intact glomeru…
A symmetric nonlocal damage theory
2003
The paper presents a thermodynamically consistent formulation for nonlocal damage models. Nonlocal models have been recognized as a theoretically clean and computationally efficient approach to overcome the shortcomings arising in continuum media with softening. The main features of the presented formulation are: (i) relations derived by the free energy potential fully complying with nonlocal thermodynamic principles; (ii) nonlocal integral operator which is self-adjoint at every point of the solid, including zones near to the solid's boundary; (iii) capacity of regularizing the softening ill-posed continuum problem, restoring a meaningful nonlocal boundary value problem. In the present app…
A review of colour center and nanostructure creation in LiF under heavy ion irradiation
2015
A study of radiation damage in LiF crystals under irradiation with MeV–GeV energy ions, from 12C to 238U, at temperatures varying from 8 to 300 K, depending on the ion energy, energy loss and irradiation temperature, is presented. For light ions (12C, 14N) at low fluences, it is mainly color centers that are created. Increasing the fluence leads to the overlapping of tracks and the creation of more complex color centers, defect aggregates and dislocations. For ions with an energy loss above a threshold value (dE/dx = 10 keV nm−1) the tracks exhibit a central core damage region with a radius of 1–2 nm, surrounded by an extended halo which mainly contains single color centers. In this case, i…
Familial hypercholesterolæmia in children and adolescents: Gaining decades of life by optimizing detection and treatment
2015
Contains fulltext : 155263.pdf (Publisher’s version ) (Open Access) Familial hypercholesterolaemia (FH) is a common genetic cause of premature coronary heart disease (CHD). Globally, one baby is born with FH every minute. If diagnosed and treated early in childhood, individuals with FH can have normal life expectancy. This consensus paper aims to improve awareness of the need for early detection and management of FH children. Familial hypercholesterolaemia is diagnosed either on phenotypic criteria, i.e. an elevated low-density lipoprotein cholesterol (LDL-C) level plus a family history of elevated LDL-C, premature coronary artery disease and/or genetic diagnosis, or positive genetic testin…
Ozone-induced reductions in below-ground biomass: an anatomical approach in potato
2010
[EN] Potato plants were grown in open-top chambers under three ozone concentrations during two complete cropping seasons (93 and 77 d in 2004 and 2005, respectively). The effects of chronic exposure to ozone on leaf anatomy, cell ultrastructure and crop yield were studied. Severe cell damage was found, even at ambient ozone levels, mainly affecting the spongy parenchyma and areas near the stomata. Damage to the cell wall caused loss of cell contact, and loss of turgor pressure due to tonoplast disintegration, contributed to cell collapse. Phloem sieve plates were obstructed by callose accumulation, and damaged mesophyll cells increased their starch stores. Tuber yield fell sharply (24–44%),…
Adaptive Planning in-Service Inspections of Fatigued Structures in Damage Tolerance Situations via Observations of Crack Growth Process
2017
From an engineering standpoint the fatigue life of a fatigued structure consists of two periods: (i) crack initiation period, which starts with the first load cycle and ends when a technically detectable crack is presented, and (ii) crack propagation period, which starts with a technically detectable crack and ends when the remaining cross section can no longer withstand the loads applied and fails statically. The main aim of this paper is to present more accurate innovative stochastic fatigue model for adaptive planning inspections of fatigued structures in damage tolerance situations via observations of crack growth process during a crack propagation period. A new crack growth equation is…