Search results for "COMPOSITE"
showing 10 items of 4584 documents
Influence of Mn site doping on electrical resistivity of polycrystalline La1-yAyMn1-xBxO3 (A=Ba, Sr; B=Cu, Cr, Co) Manganites
2008
We have the measured electrical resistivity of La1-yBayMn1-xCuxO3 (0.17?y?0.30; 0.04?x?0.10), La1-ySryMn1-xCrxO3 and La1-ySryMn1-xCoxO3 (0.270?y?0.294; 0.02?x?0.10) polycrystalline samples in the 25-325 K temperature range. The increase of Mn site doping concentration leads to an increase of the electrical resistivity of the samples and the appearance of a ?double-peak? structure in the electrical resistivity versus temperature graphs. The first peak represents the insulator-metal transition in vicinity of the paramagnetic-ferromagnetic transition (TC). We have found that the intensity of the second peak increases with an increase of concentration of Mn substituents, due to the hole scatter…
Bisfenola A saturošo zobārstniecības kompozītu genotoksicitāte
2019
Daži zobārstniecībā izmantojamie sveķu kompozīti satur monomērus ar BPA kā bāzes elementu, kas izraisa dzīvo šūnu genotoksicitāti un spēj izraisīt dzīvo šūnu nāvi. Šie monomēri spēj noārdīties cilvēka siekalās esošo esterāžu iedarbībā, tādējādi izdalot toksiskos noārdīšanās produktus mutes dobumā. Izdalītie monomēri pat var iekļūt asinsritē, izejot cauri zoba struktūrām uz pulpu. Šī pētījuma mērķis bija izpētīt zobārstniecības kompozīta materiālu ietekmi uz cilvēka asins šūnām, tieši uz limfocītiem, un novērtēt šūnu DNS bojājumu līmeni. Lai izpētītu šo jautājumu, 4 dažādi komerciāli pieejamie zobārstniecības kompozīta materiālu fragmenti tika izmērcēti izolētās cilvēka perifēro asiņu mononu…
Strain Measurement on Composites: Effects due to Strain Gauge Misalignment
2011
The present work analyses the errors affecting the strains measured by misaligned strain gauges installed on orthotropic-composite laminae. Various analytical relationships are derived showing that, besides the fibre and strain gauge orientations, the misalignment error in unidirectional off-axis orthotropic composite samples depends also on the lamina stiffness properties (E(1), E(2), nu(12), G(12)). If the fibres are aligned with the loading axis, it is found that the higher Poisson's ratio nu(12) is the only elastic property influencing the misalignment error. Experimental results are shown confirming the theoretical predictions.
Atmospheric pressure non-equilibriumplasma for the production of composite materials
2014
In the evolving field of tissue engineering, continuous advances are required to improve scaffold design and fabrication to obtain biomimetic supports for cell adhesion, proliferation, penetration and differentiation. Both electrospun fibrous scaffolds and hydrogels are used in this field since they well reproduce the structure of the extracellular matrix (ECM) of many biological tissues. Limitations of these two types of materials can be overcome through their combination, by developing composite structures combining enhanced mechanical properties (provided by the fibrous components) and improved cell penetration (provided by the gel phase) in a superior ability to mimic natural ECM that i…
Photoreforming of organics in aqueous suspension of Nb2O5/C3N4 composites to obtain H2
2023
Photocatalysis based on the use of semiconductors has gained, during the recent years, increased attention as promising sustainable process for H2 and fine chemicals production, given the possibility of activating such photocatalysts by visible light radiation. The photo-reforming activity in this work has been measured under both UV-LED irradiation and natural sunlight illumination. Moreover, the presence of metallic Pt as co-catalysts has been studied. Carbon nitride (C3N4) based materials are good candidates for solar energy conversions. The choice of C3N4 and Nb2O5 arises from the fact that their heterojunction can lead to lower recombination between the photo-generated electrons and ho…
Postbuckling analysis of cracked stiffned plates by pb–2 Rayleigh-Ritz method
2015
A Rayleigh-Ritz approach for the analysis of buckling and post-buckling behavior of cracked composite stiffened plates is presented. The structure is thought as the assembly of plate elements modeled by the first order shear deformation theory. Continuity along the edges common to contiguous elements are enforced by using penalty techniques, which also allow to straightforwardly implement efficient crack modeling strategies. General symmetric and unsymmetric stacking sequences are considered and numerical procedures have been developed and used to validate the present solution by comparison with FEA results. Original results are also presented for post-buckling solution of multilayered stif…
Complex composite structures with integrated piezoelectric transducers
2016
International audience; Nowadays, in different industrial fields as transport or aerospace, a research effort is conducted to reduce the structural weight. One of the most promising solutions is the use of composite structures due to their high stiffness, their low mass density and their low damping factor. At the same time, there is an intensification of the operational dynamic environment and an increase of durability requirements. These different expectations seem to be contradictory. One solution to manage these points is to design and manufacture smart composite structures with a fully distributed set of integrated piezoelec-tric transducers. These structures are able to modify their m…
Piezoelectric patches for the active repair of delaminated structures
2009
The Durability of Composite Wood-Steel Systems
2010
Nell’ambito della valutazione e del controllo della qualità tecnologica in edilizia, la conoscenza del comportamento nel tempo dei prodotti e componenti complessi per l’edilizia, risulta aspetto fondamentale, in particolare per quei prodotti tecnologicamente “innovativi” per i quali la normativa non prevede ancora prove specifiche per valutarne la durabilità. In particolare, oggi risulta sempre più diffuso l’impiego di sistemi assemblati o con connessioni tra materiali di diversa natura, tra cui i sistemi legno-acciaio, ottenuti rinforzando le travi in legno lamellare con piastre in acciaio forate, incollati mediante una resina epossidica bicomponente. Tali sistemi, che sono stati già ogget…
Advanced Composites and Applications: Book of abstracts
2023
The section ‘Advanced Composites and Applications’ was organized by the Institute for Mechanics of Materials of the University of Latvia (LU MMI) on 16.02.2023 as a part of the annual 81th scientific conference of the University of Latvia. It was organized remotely in Zoom. The official language of the section was English. The duration of the presentation was 10 minutes. The section was devoted to the discussion of the recent results within following topics: structure and properties of polymers and polymer-based composites, long-term properties, creep, and environmental ageing, composites for advanced applications, mechanical aspects of technology, and multifunctional properties.