Search

Large dams disrupt river ecosystems, causing negative effects on fish assemblages. Few studies, however, have investigated how Neotropical fish diversity responds to river regulation in longer temporal scales. In this study, we used a multi-metric approach to investigated temporal changes in taxonomic and functional fish diversity over 15 years-period following the construction of a large dam in the Upper Tocantins River, Amazon. We analyzed biological and environmental data collected in the impounded area before (2000–2002) and after (2003–2014) river regulation. Diversity metrics responded differently to the impoundment. Some metrics were not affected, as they showed little variation over years, such as fish abundance, species, and trait richness. Other metrics changed significantly between periods, such as taxonomic composition, temporal beta diversity, and trait abundance. Species with traits that are sensitive to hydrological alterations declined in the impoundment, while sedentary species were favored. Assemblage trajectories were variable, but community structure developed into a different state in the impoundment. Landscape variables explained changes in fish dissimilarity over time. In general, our study supports the notion that fish diversity in Amazonian rivers is vulnerable to river damming, but also indicates that different metrics show particular responses to this disturbance.

In recent years, new designing of components provided by electronics and automotive industries has required higher mechanical properties and electrical conductivity. Some of the examples are mobile phone frames, automotive powertrain components and new aluminum (Al) housing components. Silver (Ag) and Al have similarities in terms of crystal lattices and atoms diameters. Consequently, the addition of Ag in Al alloys may result in improved properties. The present research focuses on better understanding of the effects of Ag additions and cooling rate variations on the length scale of the dendritic microstructure constituting a Al-5 wt.% Si alloy. One of the factors to be considered during examination of as-cast Al-Si(-Ag) alloys microstructures is the interdendritic spacing. This factor, in combination with the second phases and solid solution, is able to control the application properties. In the present investigation, the ultimate tensile strength increases from 142 MPa for the Al-5 wt.% Si-0.1 wt.% Ag alloy to 154 MPa for the Al-5 wt.% Si-2.0 wt.% Ag alloy. This difference is not observed for ductility, which is preserved essentially unchanged into an improved value of 22% for both Ag-containing alloys. The less Ag-modified alloy samples (0.1 Ag) enhanced electrical conductivity by about 2% and 4% IACS as compared to those of the Al-5 wt.% Si and the Al-5 wt.% Si-2.0 wt.% Ag alloys samples, respectively.

Deforestation of riparian areas is a major driver of biodiversity loss in aquatic ecosystems. Thus, we investigated the influence of forest cover and physical and chemical characteristics of streams on zooplankton communities in the southeastern Amazon. We addressed the following questions: (1) Are environmental factors (water physical and chemical characteristics and landscape variables) and dispersive processes (reflected in the spatial structure among sampling sites) efficient predictors of zooplankton communities in different hydrologic seasons? (2) Can zooplankton species be indicators of watersheds’ forest-cover levels? We sampled 15 streams located in nine rural settlements in northern Mato Grosso, Brazil, in the dry (August) and rainy (March) seasons of 2017. The forest-cover level had a significant effect on the physical and chemical characteristics (conductivity, dissolved oxygen, and temperature) of streams and also on the structure and composition of zooplankton communities, mainly of rotifers and testate amoebae. Areas with low vegetation cover had seasonal changes in species richness, individuals density, and zooplankton community structure. Environmental and spatial variables had no significant effect on the structure of zooplankton communities, which may indicate the strong influence of stochastic factors. Species from three zooplankton groups (rotifers, microcrustaceans, and testate amoebae) were indicators of forest-cover classes. This study provided valuable contributions to the conservation of riparian ecosystems and the use of biological indicators in environmental monitoring programs.

In the face of increasing human impacts, biomonitoring emerges as an approach to evaluate the status of these ecosystems. Our purpose was to evaluate the publications on biomonitoring in limnic environments and to answer the following questions: (i) What are the approaches in biomonitoring studies around the world? (ii) Are the countries' human development index (HDI) and the available water volume capable to influence publications on biomonitoring? (iii) How are distributed biomonitoring publications by biological groups (e.g., fish, plants, phytoplankton, zooplankton, periphyton, insects) and by environments (lotic and lentic)? To access the publications about biomonitoring in limnic environments, we performed a search in the Web of Science database, restricted between 1991 and 2016. The scientific interest in biomonitoring in limnic environments showed an increasing trend over the years. Furthermore, the countries that presented the highest number of biomonitoring publications had also high HDI values, which reflected high investments in research and development or specific legislation for water quality monitoring. Despite the significant relationship, the water volume was not a major factor influencing the research development. Our study revealed that fish, macroinvertebrates, and lotic environments were the most used for biological monitoring purposes.

The integration of species dispersal dynamics with environmental predictors has become indispensable to understanding the pattern of communities’ organization. Thus, we evaluated the relative importance of environmental and spatial variables on the structure of zooplankton metacommunities in 20 Brazilian Cerrado streams. In multivariate models, we used the Partial Redundancy Analysis and found that space is mostly responsible for determining the structuring of the zooplankton community. However, the environmental predictors did not present a significant explanation. Our results indicate that space might act as a co-variable that explains and filters spatial variation when tested between species distributions and environmental factors. We understand that metacommunity studies with stream zooplankton demand more attention because space explained only a minor part of the variation of the zooplankton community. Therefore, advances in the research for environmental variables that can predict zooplankton in the Cerrado streams are important to understand the effects of anthropogenic change on aquatic communities.

Despite the socio-environmental importance of ichthyofauna, global fish biodiversity has decreased, and the damming of rivers is one anthropogenic activity that causes this reduction. This scientometric study evaluates the main determinants, directions, and gaps of scientific research on the biodiversity of fishes that are influenced by dams. Between 1991 and 2016, there was an increase in the number of studies about this topic, in proportion to the total number of studies that were evaluated. The distribution of these studies among countries is not random, since some socioeconomic and environmental factors (e.g., gross domestic product, number of researchers, number of large dams) determine the distribution of research. Moreover, these studies mostly address the negative impacts of dams on fish communities on a local scale; several studies have shown the importance of mitigating these impacts. In this particular study, we emphasize the need to research the effects of fishing, cascading dams and the phylogenetic diversity of ichthyofauna. We find that the relationship between dams and fish has become popular among researchers, in particular those who are willing to understand the causes, consequences, and severity of these changes on the ichthyofauna.

Biomonitoring programs need to balance accurate responses in assessments of changes in biological communities with sampling that is fast and low cost. In this study, we evaluated the concordance among fish and phytoplankton communities of streams. We tested the cross-taxa surrogacy, taxonomic, numerical resolution and ecological substitute group (habitat use and trophic guilds) resolution with Procrustes analyses aim of simplifying the biomonitoring process. We collect a total fish abundance of 8,461 individuals, represented by the ecological classes of habitat, including benthic, nektonic, nektobenthic, marginal and trophic guilds by detritivore, terrestrial invertivore, aquatic invertivore, piscivore, algivore and herbivore. We sampled a phytoplankton total density of 1,466.68 individuals/ml, represented by four Morphology-Based Functional Groups and nine Reynolds Functional Groups. Our results don’t support the use of substitute groups among fish and phytoplankton. For fish, habitat use and trophic guild are good surrogates for species-level data. Additionally, our results don’t support the use of functional groups as surrogates for phytoplankton. We suggest the use of higher taxonomic levels (genus and family) and record only the occurrence of species and/or genus for fish and phytoplankton. Our findings contribute to decreasing the costs and time of biomonitoring programs assessments and/or conservation plans on fish and phytoplankton communities of headwater streams.

An experimental study is reported on heat treating rapid solidified Al-12 wt% Si alloy with 355–425 μm powder size. Fast heat treatments at 813 K revealed morphological shifts of eutectic Si from the as-atomized condition to those after annealing. The Si network of the as-atomized samples showed a fine dispersed coral fibrous architecture. This feature via rapid cooling brings the prospect of quickly disintegrating and spheroidizing Si in a few minutes without chemical modification. By adopting different exposure times, it was possible to investigate fragmentation and coarsening of the eutectic Si. The integrity of the Si network is very sensitive to the Si spheroidization treatment transforming into a network of round Si particles. It is also seen that the material softens in the earlier stages of heat treatment, especially after 2 min of heat treatment. The breakdown in Si rods in a rapidly solidified alloy is shown to take place with a mixed mechanism of interface or internal rod diffusion and diffusion of supersaturated Si through the α primary phase to the Si rods in the eutectic. The quantitative analysis of the microstructures coupled with an analytical strengthening model resulted in good agreement between experimental and calculated data.

Functional-approach studies are currently increasing in ecology. However, for zooplankton communities, studies are mostly concentrated in marine environments. This study provides a systematic review to reveal the trends and gaps in scientific literature regarding zooplankton functional-approach in continental aquatic environments, including its main groups (testate amoebas, cladocerans, copepods, and rotifers). We focused on determining which functional traits were evaluated for these groups and whether they were based on direct measurements or on literature. We found that despite the recent increase in publications, most studies were limited to Canada, USA, Brazil, and Italy. Publications have been increasing over the last 3 years, representing an advance toward the understanding of the dynamics of these organisms in relation to environmental variations. Most studies used size-related functional traits. Nonetheless, other studies that deal with dietary and feeding strategies have improved the understanding of the dynamics of these organisms. Therefore, we highlight that the use of functional approach is an important tool to understand ecosystem processes and thus to contribute to the knowledge of biodiversity conservation and ecosystem dynamics.

Ternary Al–15 wt% Cu–7 wt% Si and Al–22 wt% Cu–7 wt% Si alloy specimens were generated by transient directional solidification (DS) and rapid solidification (RS) techniques. The microstructures are constituted by an α-Al dendritic matrix surrounded by two eutectic, that is, a binary eutectic (Si + α-Al) and a bimodal eutectic, consisting of cellular-type binary eutectic colonies (α-Al + Al2Cu) in a ternary eutectic matrix consisting of α-Al + Al2Cu + Si. The bimodal eutectic exists at cooling rates from 0.5 to 250 K/s. The secondary dendritic spacing, λ2, of the DS samples varied from 5 to 20 µm and from 10 to 18 µm for both examined alloys. The λ2 from 2.7 to 4.0 µm characterized the RS samples. Mechanical properties have been determined for various samples related to different dendritic spacing values. Based on the evaluation of the rapidly solidified microstructures, it was possible to assess the cooling rates.

This work explored and contrasted the effect of microstructure on the tensile properties of AlSi10Mg alloys generated by transient directional solidification depending on variations in cooling rate and Magnesium (Mg) content (i.e., 0.45 and 1wt.% Mg), with a focus on understanding the dendritic growth and phases constitution. Optical and Scanning electron (SEM) microscopies, CALPHAD and thermal analysis were used to describe the microstructure, forming phases and resulting tensile properties. The findings showed that the experimental evolution of the primary dendritic spacing is very similar when both directionally solidified (DS) Al-10wt.% Si-0.45wt.% Mg and Al-10wt.% Si-1wt.% Mg alloys samples are compared. The secondary dendritic spacing was lower for the alloy with more Mg, especially considering the range of high growth velocities. Moreover, a greater fraction of (Al+Si+Mg2Si) ternary eutectic islands surrounding the -Al dendritic matrix was noted for the alloy with 1wt.% Mg. As a result of primary dendritic spacings greater than 180 m related to lower cooling rates, slightly higher tensile properties were attained for the Al-10wt.% Si-0.45wt.% Mg alloy. In contrast, combining dendritic refining (< 150 m) and larger Mg2Si fraction, fast solidified DS Al-10wt.% Si-1wt.% Mg samples exhibited higher tensile strength and elongation. The control of cooling rate and fineness of the dendritic array provided a new insight related to the addition of Mg in slightly higher levels than conventional ones, capable of achieving a better balance of tensile properties in AlSi10Mg alloys.

Made available in DSpace on 2021-06-25T10:34:39Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-05-01 Objective: To evaluate the effect of treatment with fluoridated toothpaste supplemented with a combination of sodium trimetaphosphate (TMP) and casein phosphopeptide-amorphous calcium phosphate (MI Paste Plus®) on the demineralization of dental enamel. Methods: Bovine enamel blocks selected by initial surface hardness (SHi) were randomly allocated into six groups (n = 12), according to the test toothpastes: (1) without F-TMP-MI Paste Plus® (Placebo); (2) 1100 ppm F (1100F); (3) MI Paste Plus®; (4) 1100F + MI Paste Plus® (1100F-MI Paste Plus), (5) 1100F + 3 % TMP (1100F-TMP); and (6) 1100F-TMP + MI Paste Plus® (1100F-TMP-MI Paste Plus). Blocks were treated two times per day with slurries of toothpaste (1 min), and groups 4 and 6 received an application of MI Paste Plus (3 min). Next, the samples were subjected to five pH cycles (demineralizing/remineralizing solutions) at 37 °C, to produce subsurface enamel lesions.Thereafter, the blocks were maintained for 2 days in fresh remineralizing solution. After pH cycling, the following were obtained: percentage of surface hardness loss (%SH); integrated loss of subsurface hardness (ΔKHN); profile analysis and lesion depth subsurface through polarized light microscopy (PLM); scanning electron microscopy (SEM); and fluoride (F), calcium (Ca), and phosphorus (P) in the enamel. The data were subjected to ANOVA (1-criterion), followed by the Student–Newman–Keuls test (p < 0.001). Results: The 1100F-TMP-MI Paste Plus group showed better results for SHR, ΔKHN, and PLM (p < 0.001). The F concentration was similar among all groups (p > 0.001). The 1100F-TMP-MI Paste Plus group showed the highest concentration of Ca and P in the enamel (p < 0.001). Conclusion: The application of 1100F-TMP-MI Paste Plus promoted a higher inhibitory effect against enamel demineralization. Clinical significance: The combination of treatments with F, TMP, and MI Paste Plus® can be an effective alternative to improve the oral health of individuals, especially those with high activity of dental caries and at high risk for its development. Department of Preventive and Restorative Dentistry São Paulo State University (UNESP) School of Dentistry Araçatuba, Rua José Bonifácio 1193 Department of Materials Engineering Federal University of São Carlos - UFSCar Feinberg School of Medicine Ann and Robert Lurie Children’s Hospital Northwestern University School of Dentistry University of Ribeirão Preto—UNAERP Department of Preventive and Restorative Dentistry São Paulo State University (UNESP) School of Dentistry Araçatuba, Rua José Bonifácio 1193

There is continuing interest to develop lightweight and strong alloys for the aerospace sector. The advent of 3D printing has spurred a search for alloys developed for these processes. One such alloy of interest is the Al–10 wt%Si–0.45 wt%Mg–0.4 wt%Sc that has been developed and used in laser powder bed 3D printing. This study is focused on characterizing the microstructures of the atomized Al-10 wt%Si–0.45 wt%Mg–0.4 wt%Sc alloy to provide a basis for understanding the microstructural evolution of this alloy during processing. The atomized powders were separated into four size ranges. Each range was quantitatively characterized by determining its dendritic length scale and hardness. Mean spacing values from 1.5 μm to 5.5 μm could be associated with hardnesses from 105 HV to 120 HV, with higher hardness related to lower spacing. The 3D Si growth morphologies were found to fall into two distinct groupings. The first was a mixture of skeletal Si plates and in-plane Si rods for the largest particle sizes. The second grouping was related more specifically to powders with

Given the need to understand the current approaches to Environmental Education (EE) in the world, we answer the following questions: (i) Have the studies directed to EE received attention from the scientific community? (ii) what are the trends in EE publications? In the past years, there has been an increase in the number of publications on EE. Brazil stood out in the number of publications, reflecting the concern of Brazilian researchers to promote sustainability and biodiversity maintenance. As for the approaches, the studies are broad, ranging from the influence of policies on environmental protection to the importance of reflection at a global level, proposing international agreements. However, regarding the EE application, given the multiple existing currents, it is worth emphasizing the importance of the teaching-learning process to take place critically so that there is no favoring of the contents promoted and supported by a hegemonic class.

Understanding the mechanisms that generate organism distribution patterns from the beta diversity perspective can assist in environmental monitoring strategies. In this study, we emphasized the limnic zooplankton due to the ability of these organisms to respond quickly to environmental variations. Therefore, we evaluated the following questions: (i) Do different regions of the same lake have the same importance in contributing to beta diversity? (ii) Do beta diversity and its components vary over the hydrological cycle? (iii) What is the importance of local and spatial predictors in beta diversity and its components? (iv) Do beta diversity and its components show a consistent pattern throughout the hydrological cycle? We found that the contribution of different sites to diversity was more associated with regions with low abundance and richness of organisms values, such as the littoral and igarapes, which shows the relevance of these areas for biological monitoring and for the delimitation of priority areas for the zooplankton diversity conservation. Despite the peculiarities of each hydrological period and regarding beta diversity components, we verified a species substitution and differences in abundance pattern in the lake. We also found low concordance patterns between the periods and low environmental and spatial variables prediction on beta diversity patterns.

Sn-Bi-based Thermal Interface Materials (TIM) are adequate alloys to promote heat dissipation in power electronics. However, despite the necessary thermal connection, mechanical support for different components and substrates are of prime importance in microelectronic devices. In this framework, the effects of Antimony (Sb) additions on the microstructure and tensile properties of the Sn-52 wt% Bi alloy are investigated. Various Sn-Bi(-Sb) samples solidified at different cooling rates and two levels of Sb-containing alloys allow a comprehensive examination of length scales of either dendritic or eutectic microstructures. A number of experimental techniques are used here to permit a sound analyses of the ternary Sn-Bi(-Sb) alloys: transient directional solidification, optical microscopy (OM), triangle and intercept quantification methods, scanning electron microscopy (SEM), x-ray fluorescence (XRF), x-ray diffraction (XRD), tensile tests and fractography. The addition of Sb enhances the nucleation of primary dendritic trunks, which resulted in a decrease in the primary dendritic arm spacing (λ1) by about 5 times for the Sn-52 wt% Bi-2 wt% Sb alloy as compared to the results for the binary Sn-Bi alloy. The relationships found for tensile properties as a function of the secondary dendritic arm spacing (λ2) demonstrate that Sb additions increase the alloy strength while preserving the ductility. This is due to very thin SnSb intermetallic particles formed in the Sn-rich dendritic matrix. The influence of λ2 variation on both the yield and ultimate strengths is roughly insignificant while the ductility varies strongly between 14.4% and 52% for samples solidified from 0.05 °C/s to 5.0 °C/s respectively. When 2.0 wt% Sb is added, there is a maintenance in the levels of ductility as those found for the binary Sn-Bi alloy. This occurs especially for very refined dendritic and eutectic microstructures samples, which also exhibit a ductile fracture mode.

International audience; Al-based monotectic alloys show an interesting combination of wear resistance and mechanical strength. While self-lubricating bismuth (Bi) guarantees an adequate wear resistance, the modification with copper (Cu) can increase the ability to support load. Tailoring the micromorphology of the α-Al phase as well as the distribution of the inclusions of Bi embedded in the α-Al matrix is of prime importance in order to improve the properties. In this paper, various solidification experiments are performed with the Al-3.2wt.%Bi-3wt.%Cu monotectic alloy. Real-time radiographs could be acquired during solidification by using the laboratory device SFINX (Solidification Furnace with IN situ X-radiography). The processing conditions could be chosen in such a way that both cellular and dendritic morphologies of the α-Al phase could be clearly seen in a single test.Micromorphological transitions from dendrites to cells are recognized for samples solidified from different cooling rates, i.e. 0.025 K/s and 0.01 K/s. Measurements of the α-Al dendrite velocity and growth parameters of the Bi droplets during solidification have also been extensively performed. A comprehensive model for the cellular-to-dendritic (CDT) transition of Al-based monotectic alloys is outlined. The model considers the interactionbetween α-Al and Bi droplets during solidification and its impact on the microstructure.

Al-Si alloys are very important in the automotive industry. This is thanks to their high strength to weight ratio, suitable fluidity, good corrosion resistance and high productivity. The shape of the eutectic Silicon (Si) has been widely studied since it is considered an index of quality regarding many application properties. Understanding the effects of alloy additions on the morphology of Si has drawn researcher’s attention. One of these elements of interest is Bismuth (Bi), which may be part of the composition of Al-Si alloys either as an addictive or a contamination. Hence, the microstructure aspects related to the presence of Bi are important requiring further consideration. In the present study, Al-15wt% Si hypereutectic alloy is modified with 1.0 wt% Bi. The goal is to compare the effect of this addition on the morphology of the phases forming the microstructure and on tensile/wear properties. In order to pursue that comparison, previously available data for the binary Al-15wt% Si alloy will be used. Various samples characterized by distinct cooling rates were generated by transient directional solidification of the ternary Al-Si-Bi alloy. The experimental variations of the eutectic spacing will be compared to each other based on their trends. It was found that the addition of minor Bi content (∼1%) permitted tensile strength and ductility of 195 MPa and 14%. Furthermore, wear resistance was improved thanks to Bi. The reasons for that will be outlined.

The roles of Bismuth (Bi) and Antimony (Sb) additions to hypereutectic Al-Si alloys with significant variation in solidification cooling rates have yet to be unraveled. Both elements are considered of importance in the production chain of Al-based metallurgical products: while Sb is a refiner of the eutectic Si, Bi remains important in applications requiring better levels of alloy machinability. Based on these verified realities, the present research aims to modify the Al-15 wt% Si hypereutectic alloy with 1.0 wt% Bi as well as with 1.0 wt% Sb. The implications of these incorporations on the characteristics of the microstructure phases and the tensile/wear properties are examined. Various samples characterized by distinct solidification rates have been generated through transient directional solidification experiments. Several methods were used to examine and compare the two alloys with each other: microstructure and segregation are investigated by CALPHAD simulations, optical microscopy, scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS), whereas wear and tensile properties have been determined through standardized measurements. While adding Sb provides the growth of broken Si in the form of lamellae and some fraction of fibers for higher solidification rates, Bi alloying preserves lamellar growth for all rates examined. Adding Bi is better than Sb in reaching higher tensile properties, but Sb presence provides greater wear resistance. Both alloying elements ductilize the brittle Al-15 wt% Si alloy.

Because the Amazon rain forest is ecologically relevant on a global scale, we applied scientometric techniques to integrate studies dealing with mercury research in this unique ecosystem between 1991 and 2017. Using a combination of co-authorship and co-citation analyses, keyword mapping and overlay visualization of topics in the field, this article identified three major areas in the 26-year period of mercury research: (1) human exposure to mercury (artisanal small-scale gold mining-ASGM) and methylmercury through fish consumption, and their respective risks for human health, (2) mercury accumulation in the environment and its relation to ASGM and atmospheric concentration, and (3) mercury geochemistry and its presence in soils, sediments, and water. The paper also identified the leading institutions related to the published research and respective influential scholars in the context of this study. Overall, the analyses revealed patterns of convergence and divergence between authors, specialization, and interdisciplinary engagement in mercury investigation, thus highlighting strengths and weaknesses of research topics in the field. This scientometric approach could be a useful tool to monitor/assess the implementation of the Minamata Convention.

Made available in DSpace on 2021-06-25T10:46:36Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-02-01 Objective: To evaluate the effects of combination of treatments with fluoridated toothpastes supplemented with sodium trimetaphosphate (TMP) and casein phosphopeptide-amorphous calcium phosphate (MI Paste Plus®), on the remineralization of dental enamel. Design: Enamel blocks with artificial caries were randomly allocated into six groups (n = 12), according to the toothpastes: 1) without F-TMP-MI Paste Plus® (Placebo); 2) 1100 ppm F (1100 F), 3) MI Paste Plus®, 4) 1100 F + MI Paste Plus® (1100 F-MI Paste Plus®), 5) 1100 F + 3% TMP (1100 F-TMP) and 6) 1100 F-TMP + MI Paste Plus® (1100 F-TMP-MI Paste Plus®). Blocks were treated 2×/day with slurries of toothpastes (1 min). Furthermore, groups 4 and 6 received the application of MI Paste Plus® for 3 min. After pH cycling, the percentage of surface hardness recovery (%SHR); integrated loss of subsurface hardness (ΔKHN); profile analysis and lesion depth subsurface through polarized light microscopy (PLM), confocal laser scanning microscopy (LSCM), scanning electron microscopy (SEM), fluoride (F), calcium (Ca), phosphorus (P) concentrations in the enamel were determined. The data were analyzed by ANOVA (1-criterion) and Student-Newman-Keuls test (p < 0.001). Results: 1100 F-TMP-MI Paste Plus® group showed the best results of %SHR, ΔKHN and PLM (p < 0.001). F concentration was similar between the 1100 F, 1100 F-MI Paste Plus®, and 1100 F-TMP-MI Paste Plus® groups (p > 0.001). 1100 F-TMP-MI Paste Plus® group showed the highest concentration of Ca and P in the enamel (p < 0.001). Conclusion: The association of 1100 F-TMP and MI Paste Plus® led to a significant increase in the remineralization of initial carious lesions. São Paulo State University (UNESP) School of Dentistry Araçatuba Department of Preventive and Restorative Dentistry, Rua José Bonifácio 1193 Araçatuba Federal University of São Carlos - UFSCar Department of Materials Engineering Northwestern University Feinberg School of Medicine Ann and Robert Lurie Children's Hospital School of Dentistry University of Ribeirão Preto - UNAERP São Paulo State University (UNESP) School of Dentistry Araçatuba Department of Preventive and Restorative Dentistry, Rua José Bonifácio 1193 Araçatuba

The growth of eutectic colonies in Sn–Cu, Sn–Zn and Sn–Ag–Cu eutectic alloys has already been reported in the literature. However, relationships between this kind of microstructure and mechanical properties remain undetermined for solders. The use of water-cooled copper (Cu) and AISI 1020 low-C steel molds and the eutectic Sn-9 wt.%Zn alloy make it possible to address this matter. The samples grown in the Cu mold demonstrated higher solidification rates than those developed in the low-C steel mold. Overall, the microstructure is constituted by Zn-lamellae embedded in a Sn-rich matrix. The Zn lamellae are not only uneven in thickness but also irregularly perforated. Due to Cu dissolution into the alloy, a small fraction of Cu5Zn8 intermetallic particles formed during solidification of the Sn-9 wt.%Zn alloy in the Cu mold. The contamination with Cu appears to be responsible for the improvement in the distribution of Zn-lamellae. The decrease in spacing between broken lamellae measured from SEM images, as well as a higher number of Zn particles per area, explain such occurrence. Ductility and tensile strength of different samples could allow the establishment of relationships among properties vs. eutectic colony spacing. For the Cu mold, the motion of Cu towards the alloy as well as higher solidification rates, allowed microstructures to be formed combining 60% of strain to fracture and 52 MPa of ultimate tensile strength. These achievements are mainly due to the finest spacings of both the eutectic colony (λχ = 36 μm) and the Zn lamellae (λL=0.9 μm), besides homogeneous distribution of Cu across the resulting microstructure.

Zooplankton plays a key role in aquatic food chains. In the present study we aimed to evaluate the trends of zooplankton studies in the scientific literature published between 1991 and 2015 and also to answer the following questions: (i) Has the number of studies increased? (ii) Which are the main countries and journals that publish papers about zooplankton? (iii) Is it possible to identify temporal trends? We used the ISI Web of Science database to find articles that had the word “ zooplankton ” or its groups (“ copepods ”, “ cladocerans ”, “ rotifers ”, “ testate amoebae ”) in their title, abstract or keywords. The number of zooplankton publications increased over the years, but, when we removed the effect of total publications, the number of publications on copepods decreased, while publications on testate amoebae increased. The country with the most published studies was the USA and the journal was the Hydrobiologia . The keywords formed four groups, evidencing a temporal change in the main interest of the studies on zooplankton community. The oldest articles showed the interest of researches in zooplankton species description. In subsequent years, the main concern was still species description, but also ecology and other aspects. Recently, studies concerned to environmental issues, preservation and sustainability became more frequent. Keywords: systematic review, scientific interest, limnology, water, food chain.

Ternary Al-11wt %Si-(xwt %)Cu alloys are highly recommended as commercial filler metals for aluminum brazing alloys. However, very little is known about the functional inter-relations controlling the solidified microstructures characterizing processes such as torch and furnace brazing. As such, we evaluated two commercial brazing alloys, which are the Al-11wt %Si-3.0wt %Cu and Al-11wt %Si-4.5wt %Cu alloys: Cu contents typically trend in between the suitable alloying spectrum. We analyzed the effects of solidification kinetics over features such as the dendrite arm spacing and the spacing between particles constituting the eutectic mixture. Also, tensile properties were determined as a function of the dendrite microstructure dimensions. The parameters concerned for translating the solidification kinetics were either the cooling rate, or growth velocity related to the displacement of the dendrite tip, or the eutectic front. The relevant scaling laws representing the growth of these brazing alloys are outlined. The experimental results demonstrated that a 50% increase in Cu alloying (from 3.0 to 4.5 wt %) could be operated in order to obtain significant variations in the dendritic length-scale of the microstructure across the produced parts. Overall, the microstructures were constituted by an &alpha, Al dendritic matrix surrounded by a ternary eutectic consisting of &alpha, Al + Al2Cu + Si. The scale measurements committed to the Al2Cu eutectic phase pointed out that the increase in Cu alloying has a critical role on refining the ternary eutectic.

Current applications of Al–Fe–Ni alloys include Alnico permanent magnets, industrial furnaces, and cladding of nuclear fuel plates. In spite of industrial interest, limited knowledge regarding to inter-relations between microstructure and mechanical resistance can be noted to date. Thus, the aim of the present contribution is, firstly, to analyze the microstructure features of α-Al phase (size and morphology) during atomization of the ternary Al-1wt%Fe-1wt%Ni alloy, including determination of cooling rates and hardness of the obtained powders. Secondly, the nature, size and distribution of intermetallic compounds (IMC), strength and ductility of hot consolidated bulks by extrusion from two different ranges of Al-Fe-Ni powder size (powder size between 75 and 106 μm and powder size up 106 μm and less 180 μm) are examined. The sequence of processes includes nitrogen gas atomization followed by compaction and hot extrusion consolidation at both 350 °C and 400 °C. The procedures to characterize the samples involve X-ray diffraction (XRD), optical microscopy, scanning electron microscopy (SEM), Vickers hardness and mechanical tensile tests. Al-rich cells prevailed for either smaller or larger Al-1wt%Fe-1wt%Ni atomized powders with formation of IMCs not only in the cell walls but also precipitated within the α-Al matrix. Strength and ductility of as-extruded samples are found to be consistent with their microstructures.

Aim: In order to contribute to the knowledge about the simplification of biological surveys, this study evaluated the use of substitute groups, numeric and taxonomic resolution for the three main groups of zooplankton (cladocerans, copepods and rotifers) in a Hydropower Plant (UHE). The following issues were addressed: (i) the patterns of spatial and/or temporal ordering generated between each zooplankton group are in concordance? (ii) The concordance is maintained using presence/absence data instead of density data? (iii) The identification of organisms to the species level can be replaced by genus or family level? Methods Samples were taken in seven sample units over five campaigns between 2009 and 2010 in the UHE Serra da Mesa (Goiás, Brazil). To evaluate the correlation between each pair of matrices was used the Mantel test. Results The results demonstrate that the replacements should not be made among the zooplanktonic groups, requiring the monitoring of three groups (copepods, cladocerans and rotifers). Furthermore, the results suggest the use of density data of individuals rather than just presence/absence of species. Finally, the results of this study indicate the possibility to use data at species level instead of data at genus or family level. Conclusion For zooplankton community monitoring purposes only the use of taxonomic resolution showed to be efficient for this area of study, not being recommended the use of surrogate groups or numerical resolution. Resumo Objetivo: A fim de contribuir para o conhecimento a respeito da simplificação de levantamentos biológicos, o presente estudo avaliou o uso de grupos substitutos, resolução taxonômica e numérica para os três principais grupos da comunidade zooplanctônica (cladóceros, copépodes e rotíferos) em uma Usina Hidrelétrica (UHE). As seguintes questões foram abordadas: (i) Os padrões de ordenação espacial e/ou temporal gerados entre cada grupo zooplanctônico são concordantes? (ii) A concordância se mantém utilizando dados de presença e ausência em substituição a dados de densidade? (iii) A identificação dos organismos em nível de espécie pode ser substituída por gênero ou família? Métodos Foram realizadas coletas em sete unidades amostrais ao longo de cinco campanhas entre os anos de 2009 e 2010 na UHE de Serra da Mesa (Goiás, Brasil). Para avaliar a correlação entre cada par de matrizes foi utilizado o teste de Mantel. Resultados Não se deve realizar substituições entre os grupos zooplanctônicos, sendo necessário o monitoramento dos três grupos (copépodes, cladóceros e rotíferos). Além disso, sugerimos a utilização de dados de densidade de indivíduos ao invés de apenas dados de presença/ausência de espécies. Por fim, os resultados deste estudo indicam a possibilidade de dados em nível de espécies serem substituídos por dados em nível de gênero ou família. Conclusão Para fins de monitoramento da comunidade zooplanctônica, apenas o uso da resolução taxonômica mostrou-se eficiente para esta área de estudo, não sendo recomendado o uso de substitutos nem resolução numérica entre os grupos.

A Bacia do Rio Araguaia é uma região cujos ambientes mostram-se marcados pelas variações anuais de inundação. A caracterização da cobertura da terra tem o potencial de caracterização do funcionamento ecossistêmico, bem como, avaliar possíveis modificações antrópicas. O presente trabalho teve como objetivo avaliar as variações espectrais de classes de uso e cobertura da terra da Ottobacia 6951, localizada no Médio curso do Rio Araguaia, no ano de 2017. Foram utilizadas imagens de reflectância da superfície terrestre do sensor Operational Land Imager (OLI) do satélite Landsat 8, referente aos períodos de transição chuva-seca (maio), seca (julho) e transição seca-chuva (outubro) de 2017. Para cada data foram geradas imagens-fração, através da técnica de mistura espectral, considerando três membros finais (natural, pastagem e água), evidenciando as mudanças da cobertura. Também foram gerados índices de vegetação para cada período, evidenciado os aspectos biofísicos da cobertura da terra. Para essa avaliação foram estabelecidos 50 pontos aleatórios para cada classe considerando a bacia inteira, cada unidade geomorfológica e uso e cobertura da terra. A avaliação dos padrões temporais da cobertura da terra considerou, especialmente, as relações de significância entre os fatores “cobertura” e “período”, para a realização de Análise Multivariada de Permutação (PERMANOVA). A avaliação de agrupamentos foi realizada por meio da Análise de Componentes Principais (ACP), que proporciona a redução da dimensionalidade dos dados. A cobertura da terra foi a variável de maior significância das mudanças intra-anuais da Ottobacia. A classe pastagem apresentou a maior variação intra-anual, expressando um comportamento mais sensível à sazonalidade. A B S T R A C TThe Araguaia River Basin is an area whose environments are marked by annual flood variations. The characterization of the land cover has the potential to characterize the ecosystem functioning, as well as to evaluate possible anthropic changes. The objective of this work was to evaluate the spectral variations of land use and land cover classes of Ottobacia 6951, located in the middle course of the Araguaia River, in the year 2017. Land surface reflectance images of the Operational Land Imager (OLI) ) of the Landsat 8 satellite, referring to the rainy-dry (May), dry (July) and dry-rainy transition (October) periods of 2017. For each date fractional images were generated, using the spectral mixing technique, considering three final members (natural, pasture and water), evidencing changes in coverage. Vegetation indexes were also generated for each period, evidencing the biophysical aspects of the land cover. For this evaluation were established 50 random points for each class considering the entire basin, each geomorphological unit and land use and coverage. The evaluation of temporal patterns of land cover considered, especially, the relations of significance between the factors "coverage" and "period", for the realization of Multivariate Analysis of Permutation (PERMANOVA). The clustering evaluation was performed through the Principal Component Analysis (PCA), which provides a reduction in the dimensionality of the data. Land cover was the most significant variable of Ottobacia's intra-annual changes. The pasture class had the highest intra-annual variation, expressing a behavior more sensitive to seasonality.Keyworks: river geomorphology, land cover seasonality, spectral mixing, vegetation indices, land use and cover.

O mundo está em alerta em relação às mudanças ambientais globais, seus efeitos sobre a biodiversidade e na capacidade de resiliência dos ecossistemas, o que leva à necessidade de pesquisas que proponham medidas mitigatórias, principalmente do setor industrial, para esses impactos antrópicos. Por meio de uma avaliação cienciométrica, as tendências globais de publicações sobre o clima em um contexto industrial foram investigadas. Nos últimos anos, um crescente número de pesquisas aborda as contribuições do setor industrial nas mudanças climáticas e as propostas de políticas públicas para mitigação dessas alterações. Esses resultados mostram que apesar das barreiras para a implementação dessas medidas de redução na emissão de gases de efeito estufa e inúmeras incertezas, mudanças nos modelos de produção industrial e nos padrões de consumo da sociedade, em nível global, são indispensáveis para o futuro do planeta.

The use of substitute groups in biomonitoring programs has been proposed to minimize the high financial costs and time for samples processing. The objectives of this study were to evaluate the correlation between (i) the spatial distribution among the major zooplankton groups (cladocerans, copepods, rotifers, and testaceans protozoa), (ii) the data of density and presence/absence of species, and (iii) the data of species, genera, and families from samples collected in the Lago Grande do Curuai, Pará, Brazil. A total of 55 sample of the zooplanktonic community was collected, with 28 samples obtained in March and 27 in September, 2013. The agreement between the different sets of data was assessed using Mantel and Procrustes tests. Our results indicated high correlations between genus level and species level and high correlations between presence/absence of species and abundance, regardless of the seasonal period. These results suggest that zooplankton community could be incorporated in a long-term monitoring program at relatively low financial and time costs. O uso de grupos substitutos em programas de biomonitoramento tem sido proposto para minimizar os altos custos financeiros e tempo para processamento das amostras. Os objetivos deste estudo foram avaliar a correlação entre (i) a distribuição espacial nos principais grupos zooplanctônicos (cladóceros, copépodes, protozoários testáceos e rotíferos), (ii) os dados de densidade e presença/ausência de espécies, e (iii) os dados de espécies, gêneros e famílias a partir de amostras coletadas no Lago Grande do Curai, Pará, Brasil. Um total de 55 amostras da comunidade zooplanctônica foi coletada, sendo 28 em março e 27 em setembro de 2013. A concordância entre os diferentes conjuntos de dados foi avaliada por meio dos testes de Mantel e Procrustes. Nossos resultados indicam alta correlação entre nível de gênero e espécies e entre a presença/ausência de espécies e abundância, independentemente do período sazonal. Estes resultados sugerem que a comunidade zooplanctônica pode ser incorporada em programas de monitoramento a longo prazo com custos financeiros e de tempo relativamente menores.

Dissertação (mestrado)—Universidade de Brasília, Faculdade UnB Planaltina, Programa de Pós-Graduação em Meio Ambiente e Desenvolvimento Rural, 2015. Diversos estudos evidenciam os efeitos do pulso sobre as características físicas, químicas e biológicas da água nas planícies de inundação. Nesse aspecto, não há como negligenciar a importância da Amazônia em termos de disponibilidade de recursos hídricos e biodiversidade. No presente estudo foi dada ênfase aos quatro principais grupos da comunidade zooplanctônica (cladóceros, copépodes, protozoários testáceos e rotíferos), sendo avaliados os efeitos do pulso de inundação sobre as características ambientais e biológicas, além do uso de grupos substitutos e resoluções numéricas e taxonômicas. Portanto, os objetivos do primeiro capítulo foram avaliar: (1.1) o efeito do pulso de inundação sobre as características ambientais e biológicas, (1.2) a variação da similaridade ambiental e biológica no ecossistema lacustre entre os períodos de enchente e vazante, (1.3) como os organismos zooplanctônicos respondem aos gradientes ambientais. Para atingir tais objetivos foram realizadas: (1.1) Análises de Componentes Principais (PCA), Análises de Escalonamento Multidimensional Não-Métrico e Análise de Similaridade (Anosim); (1.2) Betadisper; (1.3) Análise de Correspondência Canônica (CCA). Os objetivos do segundo capítulo deste estudo foram avaliar a correlação entre (2.1) a distribuição espacial nos principais grupos zooplanctônicos (cladóceros, copépodes, protozoários testáceos e rotíferos), (2.2) os diferentes níveis numéricos (dados de densidade e presença/ausência de espécies), e (2.3) os níveis taxonômicos (espécies, gêneros e famílias); Para isso foram realizadas análises de Mantel e Procrustes, permitindo uma comparação entre as diferentes matrizes a partir dos dados coletados no Lago Grande do Curai, Pará, Brasil. Os resultados evidenciaram que os grupos do zooplâncton respondem efetivamente às variações no pulso de inundação, porém apenas copépodes e rotíferos apresentaram maior dispersão durante o período da enchente. Além disso muitos táxons foram capazes de responder efetivamente às variações ambientais. Adicionalmente, os resultados do segundo capítulo, mostraram ser fracas as correlações entre os grupos do zooplâncton quando se objetiva compreender a dinâmica ecológica dos mesmos, porém, os resultados para substituições numéricas e taxonômicas (nível de gênero) mostraram alta correlação. Several studies show the effects of the pulse on the physical, chemical and biological characteristics of water in the floodplains. In this respect, there is no way neglect the importance of the Amazon in terms of availability of water resources and biodiversity. In this study the emphasis was on four main groups of the zooplankton (cladocerans, copepods, rotifers and testate protozoa), as well as evaluating the effects of the flood pulse on environmental and biological characteristics, and the use of substitute groups and numerical and taxonomic resolutions. Therefore, the objectives of the first chapter were to assess: (1.1) the effects of the flood pulse on environmental and biological characteristics, (1.2) the variation in environmental and biological similarity in the lake ecosystem between periods of flooding and flushing, (1.3) and how the zooplankton organisms respond to environmental gradients. To realize those goals were performed: (1.1) Principal Component Analysis (PCA), Non-Metric Multidimensional Scaling and Similarity Analysis (ANOSIM); (1.2) Betadisper; (1.3) Canonical Correspondence Analysis (CCA). The objectives of the second chapter of this study were to evaluate the correlation between (2.1) the spatial distribution among the major zooplankton groups (cladocerans, copepods, rotifers, and testaceans protozoa), (2.2) the different numerical levels (data of density and presence/absence of species), and (2.3) the taxonomic levels (species, the genera, and families); For this, Mantel and Procrustes analyzes were performed, allowing a comparison between the different matrices from the data collected in the Lago Grande do Curuai, Pará, Brazil. The results showed that the zooplankton groups effectively respond to changes in the flood pulse, but only copepods and rotifers presented higher dispersion during the flushing period. Also many taxa were able to respond effectively to environmental variations. Additionally, the second chapter results, shown to be weak correlations between zooplankton groups when the aim is to understand the ecological dynamics of these, however, the results for numerical and taxonomic substitutions (genus level) showed high correlation.