ORCID Profile
0000-0002-7306-0835
Current Organisations
Universidade Federal do Estado do Rio de Janeiro
,
Deakin University
Does something not look right? The information on this page has been harvested from data sources that may not be up to date. We continue to work with information providers to improve coverage and quality. To report an issue, use the Feedback Form.
Related Links
Publications
Polyacrylonitrile-based precursors and carbon fibers derived from advanced RAFT technology and conventional methods – The 1st comparative study
Publisher: Elsevier BV
Date: 12-2016
Patterns of periphyton are determined by cascading trophic relationships in two neotropical streams
Publisher: CSIRO Publishing
Date: 2010
DOI: 10.1071/MF08326
Abstract: Indirect foodweb interactions often determine the dynamics of aquatic ecosystems. Predators may reduce the activity of herbivores, which, in turn, may cause basal resources to increase. We studied the patterns of distribution of periphyton (organic and inorganic mass and chlorophyll) on rocks in pools in two Atlantic rainforest coastal streams that varied with respect to the presence or absence of fish. A steep waterfall apparently prevented most fish species from colonising the upper parts of one stream the other stream was apparently naturally without most species of fish. When fish were present, atyid shrimps and baetid mayflies were less abundant compared with parts of the streams without fish. Concomitant with this, the quantity of periphyton organic and inorganic masses was much greater in the presence of fish. Previous experiments showed that atyid shrimps (Potimirim glabra) and baetid mayflies could reduce the quantity of periphyton by grazing and bioturbation. We deduce that fish inhibit the grazing and bioturbing activities of Potimirim and baetid mayflies, which resulted in larger quantities of inorganic and organic mass of periphyton in parts of streams with fish. Cascading interactions may be common in Atlantic coastal forest streams.
Photoprotection by silk cocoons
Publisher: American Chemical Society (ACS)
Date: 19-09-2013
DOI: 10.1021/BM401023H
Abstract: A silk cocoon protects a silkworm during its pupal stage from various threats. We systematically investigated the role of fiber, sericin, and embedded crystals in the UV protection of a silk cocoon. Diffuse reflectance and UV absorbance were measured and free radicals generated during exposure to UV radiation were quantified using photoinduced chemiluminescence (PICL). We identified the response to both UV-A and UV-B radiations by silk materials and found that sericin was primarily responsible for UV-A absorption. When sericin was removed, the photoinduced chemiluminescence intensity increased significantly, indicating higher UV-A-induced reactions of cocoons in the absence of sericin. There is progressively higher sericin content toward the outer part of the cocoon shell that allows an effective shield to pupae from UV radiation and resists photodegradation of silk fibers. The study will inspire development of advanced organic photoprotective materials and designing silk-based, free-radical-scavenging antioxidants.
Effects of ephemeropterans and shrimps on periphyton and sediments in a coastal stream (Atlantic forest, Rio de Janeiro, Brazil)
Publisher: University of Chicago Press
Date: 12-2004
Chemiluminescence from UVA–exposed skin: Separating photo-induced chemiluminescence from photophysical light emission
Publisher: Elsevier BV
Date: 09-2012
DOI: 10.1016/J.JPHOTOBIOL.2012.05.022
Abstract: Several previous studies have reported luminescence emission from skin following exposure to UVA radiation in air. We show that UVA irradiation of biomaterials and polymers in oxygen, including bovine stratum corneum, followed by photon counting results in a complex emission due to a combination of photophysical processes together with photo-induced chemiluminescence (PICL). The photophysical processes include fluorescence, phosphorescence and charge-recombination luminescence. By irradiating materials in an inert atmosphere such as nitrogen and allowing photophysical light emission to fully decay before admitting oxygen, the weak photo-induced chemiluminescence generated via free radical reactions with oxygen can be separated and analysed. PICL emission from bovine stratum corneum is weaker than for wool keratin and bovine skin collagen, probably due to its higher water content, and the presence of the natural antioxidants ascorbate and tocopherol.
Rheology of polyacrylonitrile‐based precursor polymers produced from controlled (RAFT) and conventional polymerization: Its role in solution spinning
Publisher: Wiley
Date: 19-08-2016
DOI: 10.1002/APP.44273
A comparative interlaboratory study on photocatalytic activity of commercial ZnO and CeO2 nanoparticles
Publisher: Springer Science and Business Media LLC
Date: 11-09-2014
Related Organisations
University Of Southampton
Location: United Kingdom of Great Britain and Northern Ireland
Universidade Federal Do Estado Do Rio De Janeiro
Location: No location found
CEGB, Berkeley Nuclear Laboratories
Location: United Kingdom of Great Britain and Northern Ireland
University Of Warwick
Location: United Kingdom of Great Britain and Northern Ireland
Related Funding Activities
No related grants have been discovered for Roberto Silveira.