| 1. |
- de Oliveira, P. T. G., et al.
(författare)
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Comparative analysis of techniques for extrinsic characterization of CAD/CAM ceramics
- 2023
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Ingår i: Ceramics International. - : Elsevier BV. - 0272-8842. ; 49:10, s. 15044-15054
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Tidskriftsartikel (refereegranskat)abstract
- The present study aims to evaluate surface roughness and color stability of lithium disilicate and leucite ceramics after conventional and a novel surface finish techniques. Ceramic blocks (n = 84) of lithium disilicate and leucite were prepared and divided into 3 groups, being group 1: polished ceramic (negative control) (NC); group 2: stained (pigmented) ceramic followed by glaze (positive control) (PC) and group 3: simultaneous application of staining and glaze (experimental technique) (ET). Changes in luminosity and surface roughness were evaluated at 4 different time-points after a simulated brushing cycling test. Multivariate test results showed that there was a triple interaction effect between applied material, finish technique and time on their average roughness (p < 0.001) and luminosity (p < 0.05). There was no statistically significant difference in the mean roughness considering NC and ET groups for the leucite and lithium disilicate ceramics, but there was an increase in roughness mean at t1 for the PC and ET groups. Considering luminosity (materials vs. time), there was a statistically significant difference in leucite PC group. The NC and ET groups did not differ statistically from each other. There was a luminosity reduction in NC lithium disilicate ceramics for PC and NC groups. Also, analysis of color variation (Delta E) revealed significant differences for disilicate but not for the leucite groups. In leucite-based ceramic groups, surface roughness showed intermediate values between ET and the other groups at all times. Correlation analysis between roughness and luminosity presented significant results for leucite (r = 0.331; p < 0.001) and non-significant for lithium disilicate groups (r = 0.068; p > 0.05). Results suggested the possible application of the experimental technique (ET) for reduction of clinical time compared to conventional techniques, by the use of less ceramic firing cycles, with no prejudice in terms of surface roughness and luminosity over the studied time.
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| 2. |
- Leandro, S. M., et al.
(författare)
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Copepod production estimated by combining in situ data and specific temperature-dependent somatic growth models
- 2014
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Ingår i: Hydrobiologia. - : Springer Science and Business Media LLC. - 0018-8158 .- 1573-5117. ; 741:1, s. 139-152
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Tidskriftsartikel (refereegranskat)abstract
- Although growth in adult copepods is frequently assumed to be similar to juvenile growth, some evidence have pointed out that under in situ conditions, it can be lower, with, as a consequence, underestimation of secondary production. In addition, under field conditions, juvenile growth in copepods is close to maximum rates estimated at food-saturated conditions. Based on previous assumptions, this study aimed to test the applicability of a new approach for copepod production estimate, derived from temperature-dependent growth models and in situ data, such as seawater temperature and copepod biomass. For this purpose, site-specific copepod juvenile growth models, defined for Acartia tonsa and A. clausi populations from a Southern European estuary (Canal de Mira, Ria de Aveiro, Portugal), were used and copepod biomass was taken from zooplankton samples collected during 2 years at six sampling stations. By comparing the obtained results with published data, the feasibility of the approach for copepod secondary production estimates and its applicability in worldwide marine ecosystems was confirmed. Future studies should combine the estimates of adult and juvenile production in order to evaluate its relative contribution and to obtain a more precise estimate of secondary production.
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| 3. |
- Leandro, S. M., et al.
(författare)
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Growth and development of nauplii and copepodites of the estuarine copepod Acartia tonsa from southern Europe (Ria de Aveiro, Portugal) under saturating food conditions
- 2006
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Ingår i: Marine Biology. - : Springer Science and Business Media LLC. - 0025-3162 .- 1432-1793. ; 150:1, s. 121-129
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Tidskriftsartikel (refereegranskat)abstract
- A temperature-dependent growth model is presented for nauplii and copepodites of the estuarine calanoid copepod Acartia tonsa from southern Europe (Portugal). Development was followed from egg to adult in the laboratory at four temperatures (10, 15, 18 and 22 degrees C) and under saturating food conditions (> 1,000 mu g C l(-1)). Development times versus incubation temperature were fitted to a Belehradek's function, showing that development times decreased with increasing incubation temperature: at 10 degrees C, A. tonsa need 40.3 days to reach adult stage, decreasing to 8.9 days when reared at 22 degrees C. ANCOVA (homogeneity of slopes) showed that temperature (P < 0.001) and growth phase (P < 0.01) had a significant effect on the growth rate. Over the range of temperatures tested in this study, highest weight-specific growth rates were found during naupliar development (NI-NVI) and varied from 0.185 day(-1) (10 degrees C) to 0.880 day(-1) (22 degrees C) with a Q (10) equal to 3.66. During copepodite growth (CI-CV), the weight-specific growth rates ranged from 0.125 day(-1) (10 degrees C) to 0.488 day(-1) (22 degrees C) with a Q (10) equal to 3.12. The weight-specific growth rates (g) followed temperature (T) by a linear relationship and described as ln g=-2.962+0.130 T (r(2)=0.99, P < 0.001) for naupliar stages and ln g=-3.134+0.114T (r(2)=0.97, P < 0.001) for copepodite stages. By comparing in situ growth rates (juvenile growth and fecundity) for A. tonsa taken from the literature with the temperature-dependent growth model defined here we suggest that the adult females of A. tonsa are more frequently food limited than juveniles.
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| 4. |
- Leandro, S. M., et al.
(författare)
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Spatial and temporal scales of environmental forcing of Acartia populations (Copepoda: Calanoida) in the Canal de Mira (Ria de Aveiro, Portugal)
- 2014
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Ingår i: Ices Journal of Marine Science. - : Oxford University Press (OUP). - 1054-3139 .- 1095-9289. ; 71:3, s. 585-596
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Tidskriftsartikel (refereegranskat)abstract
- Zooplankton and hydrological data were collected from August 2000 and June 2002 at six stations distributed throughout Canal de Mira (Ria de Aveiro, Portugal). The abundance of Acartia clausi and Acartia tonsa adults and juveniles of Acartia spp. for each station and month were combined in a three-way data matrix, which was decomposed into three two-way matrices corresponding to different modes: biological, time, and space. Cluster analysis applied on the space mode revealed the existence of three different zones as a consequence of zooplankton composition. At each mode, principal component analysis showed strong seasonal variations in zones 1 and 2. A different spatial pattern was found between the periods November 2000April 2001 and November 2001April 2002, with the displacement of the highest abundance levels from the middle estuary to near the mouth. The congeneric populations were segregated in space: the A. clausi population was restricted to downstream stations (zone 1), whereas the A. tonsa population dominated the middle estuary. Significant correlations between hydrological parameters and copepod abundance were found to differ from zone to zone. The statistical methodology was a valuable tool to (i) discriminate spatial and seasonal distribution patterns, (ii) define estuarine sections based on the faunistic composition, and (iii) evaluate delayed effects of phytoplankton.
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| 5. |
- Leandro, S. M., et al.
(författare)
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Temperature-dependent development and somatic growth in two allopatric populations of Acartia clausi (Copepoda : Calanoida)
- 2006
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Ingår i: Marine Ecology-Progress Series. - : Inter-Research Science Center. - 0171-8630 .- 1616-1599. ; 322, s. 189-197
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Tidskriftsartikel (refereegranskat)abstract
- This study compares the effect of temperature on the post-embryonic development time and weight-specific growth rate in 2 populations of Acartia clausi from different biogeographic areas (northern and southern Europe). Development was followed from nauplius 1 to adult at 3 temperatures (10, 15 and 18 degrees C) at saturating food conditions. The relationship between development time and temperature was established by fitting Belehradek's function. The northern population had a shorter generation time at all temperatures. At 10 degrees C, the development time was estimated to be 33.9 and 36.4 d decreasing to 16.3 and 17.4 d at 18 degrees C for the northern and southern populations, respectively. Prosome length decreased with temperature, and the southern population had longer individuals at all temperatures. ANCOVA revealed a significant (p < 0.001) positive effect of temperature on the growth rates, and nauplii grew faster than copepodites (except at 18 degrees C in the southern population and 20 degrees C in the northern population). Significant differences between populations were noted during larval growth, with nauplii from the north growing faster at high temperatures (18 degrees C). The results indicate that the 2 A. clausi allopatric populations subjected to different temperature regimes have different temperature responses, in particular at high temperatures.
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| 6. |
- Tenore, K. R., et al.
(författare)
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Characterizing the role benthos plays in large coastal seas and estuaries: A modular approach
- 2006
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Ingår i: Journal of Experimental Marine Biology and Ecology. - : Elsevier BV. - 0022-0981. ; 330:1, s. 392-402
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Tidskriftsartikel (refereegranskat)abstract
- Ecologists studying coastal and estuarine benthic communities have long taken a macroecological view, by relating benthic community patterns to environmental factors across several spatial scales. Although many general ecological patterns have been established, often a significant amount of the spatial and temporal variation in soft-sediment communities within and among systems remains unexplained. Here we propose a framework that may aid in unraveling the complex influence of environmental factors associated with the different components of coastal systems (i.e. the terrestrial and benthic landscapes, and the hydrological seascape) on benthic communities, and use this information to assess the role played by benthos in coastal ecosystems. A primary component of the approach is the recognition of system modules (e.g. marshes, dendritic systems, tidal rivers, enclosed basins, open bays, lagoons). The modules may differentially interact with key forcing functions (e.g. temperature, salinity, currents) that influence system processes and in turn benthic responses and functions. Modules may also constrain benthic characteristics and related processes within certain ecological boundaries and help explain their overall spatio-temporal variation. We present an example of how benthic community characteristics are related to the modular structure of 14 coastal seas and estuaries, and show that benthic functional group composition is significantly related to the modular structure of these systems. We also propose a framework for exploring the role of benthic communities in coastal systems using this modular approach and offer predictions of how benthic communities may vary depending on the modular composition and characteristics of a coastal system. (C) 2006 Elsevier B.V. All rights reserved.
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