28 results on '"SCANNING electron microscopes"'
Search Results
2. Palynotaxonomy of Calea sect. Meyeria (Asteraceae: Neurolaeneae).
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Cartaxo-Pinto, Simone, Vieira, Ilgner Fernando Tavares, Nascimento, Jeane Marinho, Bueno, Vinicius R., Heiden, Gustavo, Mendonça, Cláudia Barbieri Ferreira, and Gonçalves-Esteves, Vania
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POLLEN , *SCANNING electron microscopes , *SECTS , *MICROSCOPES - Abstract
Calea comprises 157 species that occur in the Neotropics. The genus is organized into eight subgenera and 18 sections. Calea sect. Meyeria consists of eight species occurring exclusively in south-central Brazil. In this study, pollen grains from these eight species were sampled from herborized flower buds in pre-anthesis. Pollen samples were acetolyzed, measured, and photographed under a light microscope. Unacetolyzed pollen grains were examined under a scanning electron microscope. The results were used to characterize pollen morphology and construct a palynotaxonomic key for Calea sect. Meyeria. The analyzed pollen grains were monads, isopolar, usually medium-sized, oblate spheroidal, tricolporate, with lalongate endoaperture, the sexine echinate and thicker than the nexine, and six spines in the apocolpium region. The eight species have very similar pollen grains, but some characters are informative for this section, namely pollen size, polar area, sexine ornamentation, and endoaperture characteristics. Despite the similarity of the pollen grains, palynological analysis was able to contribute to the delimitation of Calea species, providing new information for species distinction within Calea sect. Meyeria. [ABSTRACT FROM AUTHOR]
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- 2023
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3. Development of an Epoxy Matrix Hybrid Composite with Astrocaryum Aculeatum (Tucumã) Endocarp and Kaolin from the Amazonas State in Brazil.
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Kieling, Antonio Claudio, de Macedo Neto, José Costa, del Pino, Gilberto Garcia, da Silva Barboza, Ricardo, Diáz, Francisco Rolando Valenzuela, Rivera, José Luis Valin, Fernández, Meylí Valin, Ketterer, Cristobal Galleguillos, Ortega, Alvaro González, and Abarzúa, Roberto Iquilio
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HYBRID materials , *KAOLIN , *POLYMERIC composites , *EPOXY resins , *SCANNING electron microscopes , *LIGNOCELLULOSE - Abstract
Composites with natural lignocellulosic fillers are being cited as a viable and sustainable alternative to conventional materials, as they combine lower costs with lower weight. In many tropical countries, such as Brazil, there is a considerable amount of lignocellulosic waste that is improperly discarded, which causes pollution of the environment. The Amazon region has huge deposits of clay silicate materials in the Negro River basin, such as kaolin, which can be used as fillers in polymeric composite materials. This work investigates a new composite material (ETK) made of epoxy resin (ER), powdered tucumã endocarp (PTE), and kaolin (K), without coupling agents, with the aim of producing a composite with lower environmental impact. The ETK samples, totaling 25 different compositions, were prepared by cold molding. Characterizations of the samples were performed using a scanning electron microscope (SEM) and a Fourier-transform infrared spectrometer (FTIR). In addition, the mechanical properties were determined via tensile, compressive, three-point flexural and impact tests. The FTIR and SEM results showed an interaction between ER, PTE, and K, and the incorporation of PTE and K reduced the mechanical properties of the ETK samples. Nonetheless, these composites can be considered potential materials to be used for sustainable engineering applications in which high mechanical strength is not a main requirement of the material. [ABSTRACT FROM AUTHOR]
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- 2023
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4. Paleomagnetic Constraints From 925 Ma Mafic Dykes in North China and Brazil: Implications for the Paleogeography of Rodinia.
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Hu, Yuyang, Zhao, Xixi, Peng, Peng, Yang, Fengli, D'Agrella‐Filho, Manoel S., Chen, Weiwei, and Xu, Mingchen
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PALEOGEOGRAPHY , *DIKES (Geology) , *REMANENCE , *SCANNING electron microscopes , *GEOLOGICAL time scales , *MAGNETIC measurements ,RODINIA (Supercontinent) - Abstract
Coeval Neoproterozoic mafic dykes with a well‐constrained isotopic age of 925 Ma are distributed in the North China Craton (NCC) of China and São Francisco Craton (SFC) of Brazil. Several recent studies favor the hypothesis that these two cratons were connected during 925 Ma and constituted building cratons for the supercontinent Rodinia. However, the paleo‐positions of the two cratons in Rodinia have not yet been paleomagnetically resolved. This paper presents the paleomagnetic results of these dykes in both NCC and SFC. Detailed thermal and alternating‐field demagnetization revealed that these dykes record stable components of magnetization with unblocking temperatures below the Curie temperature of magnetite. Rock magnetic results and scanning electron microscope analysis further confirm that the major magnetic minerals in dyke samples are pseudo‐single domain titanomagnetites. The mean directions of the characteristic remanent magnetization (ChRM) of the dykes are distinct from those of rocks of different ages in the sampling localities, and are supported by positive baked contact tests, indicating primary remanent magnetization. The ChRM of the SFC dykes also exhibits dual polarity. Our results suggest that the NCC and SFC were in the moderate to high paleolatitudes of the Southern Hemisphere during approximately 925 Ma, suggesting a possible paleogeographic connection between the two cratons. A new paleogeographic reconstruction of both cratons during 925 Ma is proposed, which is supported by other geological evidence. Plain Language Summary: The formation and breakup of the supercontinent Rodinia have played crucial roles in the global tectonic evolution and paleoclimate changes during the Neoproterozoic which lasted from 1.0 billion to 541 million years ago. The exact configuration of the Rodinia remains debatable, including whether the North China Craton (NCC) and São Francisco Craton (SFC) were integral components of the Rodinia. In this paper, we present new results of an integrated investigation, including paleomagnetic and rock magnetic studies and scanning electron microscope analysis, on the well dated coeval 925 Ma mafic dykes in both NCC and SFC. The results of scanning electron microscope and magnetic measurements confirm the major magnetic minerals and the stability of characteristic remanence directions. The results imply that both NCC and SFC were located at moderate to high paleolatitudes of the Southern Hemisphere during approximately 925 Ma, suggesting the possibility of a paleogeographic connection between the two cratons in the Rodinia. The findings of this study help gain improved understanding of paleogeography of the early Earth. Key Points: Characteristic remanence for the 925 Ma dykes in North China Craton and São Francisco Craton is interpreted as primaryBoth cratons were located at moderate–high paleolatitudes, southwest of Rodinia's core at 925 Ma, suggesting a paleogeographic connectionThe possible paleogeographic connection between the two cratons is supported by new paleomagnetic and geological evidence [ABSTRACT FROM AUTHOR]
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- 2022
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5. Chemical and elementary characterization of Spongiophyton nanum: Understanding the phylogeny, paleoenvironment, and fossilization processes of an enigmatic flora.
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Gaia, Geovane, Ribeiro, Victor Rodrigues, Ghilardi, Renato Pirani, Sousa, Felipe Nascimento, Llopart, Marta Pereira, and Ricardi-Branco, Fresia
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FOSSILIZATION , *SCANNING electron microscopes , *BOTANY , *PHYLOGENY , *X-ray spectrometers , *CUTICLE - Abstract
The record of thalloid macrofossils in the North-Northwest region of the Paraná Basin is less studied compared to that of invertebrate paleofauna in the same area. Consequently, the lack of important information regarding the niches occupied by thalloid embryophytes during early land colonization in this coastal paleoenvironment is evident. This study presents the first chemical and elemental data on Spongiophyton for this region of the basin, offering insights into its paleoenvironment and fossilization processes and providing considerations about the phylogeny of this enigmatic assemblage Spongiophyton nanum Kräusel emend. Chaloner et al. (1974) collected fragments from an outcropping rock in Jaciara, Mato Grosso, Brazil, and studied them using scanning electron microscope/energy X-ray dispersive spectrometer (EDS) and Fourier transform infrared (FTIR) spectroscopy techniques. The EDS analysis showed the highest elemental concentration of carbon, oxygen, and calcium as the main elements of the cuticle composition. Silicon and aluminum were better represented inside the pores than in other areas of the cuticle. The high carbon concentration in the cuticle suggested an anoxic condition prevalent during the deposition of the fine-grained sediments, which prevented its oxidation before and during diagenesis. The carbon present in the EDS spectra was restricted to the cuticle area, and the FTIR spectra indicated the presence of some functional groups, both related to the original organic matter, possibly cutin. Based on elemental characterization, the fossilization of S. nanum may involve more than one process, such as carbonification and mineralization, and S. nanum has more affinities with lichen groups. • FTIR and EDS confirm organic matter preservation in fossil cuticles. • Spongiophyton nanum fossilization involves carbonification and mineralization. • The presence of calcium and iron is linked to sediment provenance. • Anaerobic sulfur reduction aids iron incorporation in early diagenesis. • S. nanum shares metabolic pathways with lichens. [ABSTRACT FROM AUTHOR]
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- 2023
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6. Impact of acid straightener's pH value in the hair fiber properties.
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Goshiyama, Alessandra Mari, Dario, Michelli Ferrera, Lima, Cibele Rosana Ribeiro de Castro, de Araújo, Gabriel Lima Barros, Baby, André Rolim, and Velasco, Maria Valéria Robles
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COLORIMETRIC analysis , *DIFFERENTIAL scanning calorimetry , *SCANNING electron microscopes , *HAIR , *INFORMATION professionals , *TRYPTOPHAN - Abstract
Background: Acid straightener products are widely used, and it can cause changes in the hair shaft properties. The pH value of these products established by ANVISA (Brazil's National Health Surveillance Agency) as secure is above 2.0. However, the industries are interested in working at lower pH values in order to increase the straightening effect. Unfortunately, there are a lot of products in the market with pH value under the permitted. Objective: Analyze two different pH values (1.0 and 2.0) of acid straightener formulation and the influence of this difference in the hair shaft properties. In order to provide information to professionals as cosmetologists, dermatologists, and hairdressers. Methods: Combing and colorimetric analyses, tensile strength, differential scanning calorimetry (DSC), environmental scanning electron microscope (ESEM), and tryptophan content. Results: The tresses treated at pH 1.0 had a better result in the straightening capacity, improving the combing test in 59.4%, while those at pH 2.0, only in 33.0% compared with virgin hair. However, the tensile strength, at pH 1.0 decreased by 16.0% and 9.0% to the pH 2.0. In addition, the tryptophan content was lower in the tresses treated with formulation at pH 1.0. The DSC analysis showed impairment in the straightened tresses. The images by ESEM, indicated a possible formation of a film around the fiber. Conclusions: It was possible to conclude that the pH value interferes in the hair shaft properties. Tresses treated with pH 1.0 had more modifications than tresses treated with pH 2.0. [ABSTRACT FROM AUTHOR]
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- 2020
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7. REVISIÓN TAXONÓMICA DE URVILLEA (SAPINDACEAE, PAULLINIEAE): UN GÉNERO AMERICANO.
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Ferrucci, Maria Silvia
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OPTICAL microscopes , *SCANNING electron microscopes , *HERBARIA , *POLLEN , *SYNONYMS - Abstract
Background and aims: Urvillea Kunth is a small American genus of climbing shrubs or subshrubs, rarely erect subshrubs or rhizomatous hemicryptophytes. It is distributed from the southwestern United States to central Argentina, being Brazil the main center of diversity. Urvillea is characterized by its duodicogamy, trifoliated leaves and zygomorphic flowers; usually five sepals, four nectariferous lobes, anthers with a more or less conspicuous apical connective extension, and subchartaceous or chartaceous capsular fruits. Although some regional treatments are available, the only published comprehensive treatment of the genus was done by Radlkofer in 1932. The current work is the most up to date taxonomic revision of Urvillea based on modern collections and biosystematic studies. M&M: Taxonomic data were gathered from the literature, including phylogenetic studies, and from field observations, where specimens from 90 herbaria were analyzed. Morpho-anatomical observations were made with stereoscopic, optical and scanning electron microscope. Results: In this revision, 20 species of Urvillea are recognized. Most species have a wider geographical distribution than previously recognized. Nine names (eight at the species level and one form) are here lectotypified; in addition, four new synonyms are proposed. Furthermore, descriptions of pollen morphology are provided for all species. [ABSTRACT FROM AUTHOR]
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- 2020
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8. Valorization of water treatment sludge waste by application as supplementary cementitious material.
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Godoy, Luis Gabriel Graupner de, Rohden, Abrahão Bernardo, Garcez, Mônica Regina, Costa, Eugênio Bastos da, Da Dalt, Silvana, and Andrade, Jairo José de Oliveira
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WATER treatment plant residuals , *SEWAGE sludge , *WATER treatment plants , *SEWAGE sludge digestion , *SCANNING electron microscopes , *PARTICLE size distribution , *CALCINATION (Heat treatment) - Abstract
• WTS waste used as raw material to the production of new SCM. • WTS waste processed by flash calcination and electrical muffle furnace. • Different temperature and residence time investigated. • Characterization performed to verify the potential pozzolanic activity. • Calcined WTS shows great potential to the production of a new SCM. This paper investigates the potential of using calcined water treatment sludge to the development of supplementary cementitious material. Sludge samples have been collected in the drying beds of a water treatment plant located in Southern Brazil and calcined in the laboratory. Chemical and mineralogical characterization has been performed through energy dispersive X-ray spectrometry, thermogravimetric analysis, and X-ray diffraction with crystalline phases quantified by Rietveld refinement. Morphological analysis has been supported by scanning electron microscope images. Physical characterization has been carried out through specific surface area, particle size distribution, and pozzolanic activity performance with Portland cement. Results have shown that the water treatment sludge is a non-hazardous and non-inert waste without environmental restrictions for use in construction. Considering technical, environmental and economic aspects related to energy consumption, sludge samples calcined at 600 °C for 1 h present the most promising results regarding the production of supplementary cementitious material equivalent to a normal pozzolan, while highly active pozzolan requires 750 °C for 1 h. Calcined water treatment sludge showed great technical and environmental potential to be used as an alternative source of supplementary cementitious material in the near future. [ABSTRACT FROM AUTHOR]
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- 2019
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9. Caracterização e alterações morfológicas em grãos de pólen de fisális (Physalis peruviana L. (Solanaceae)) cultivada sob diferentes espectros luminosos.
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Fernandes da Silva, Daniel, Villa, Fabíola, Sabini da Silva, Luciana, Menegazzo da Silva, Giordana, and Felipe Eckert, Alesson
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POLLEN , *SCANNING electron microscopes , *CAPE gooseberry , *CULTIVATED plants , *SHADES & shadows , *GRAIN , *SOLANACEAE - Abstract
Physalis peruviana L. is a species of commercial interest belonging to the Solanaceae family, cultivated preferentially in shaded environment, which still has cultivation restricted to small areas in Brazil and therefore requires further studies. Plants are directly affected by environmental factors such as drought, temperature, radiation, among others. These factors affect not only the vegetative organs, but also reproductive structures, which may cause damage to agronomically explored plants. With the need for shading presented by the crop, the present work aimed to characterize the pollen grain and to verify the influence of shade nets used in shading on the morphology of pollen grains of this species. The work was developed at the Lavras Federal University, where three replications of two plants were cultivated under full sun and under shadenets white, blue, red and black. Flower anthesis pollen was collected, processed and photographed by scanning electron microscope (SEM). Polar diameter, equatorial diameter and pollen area were measured in ten pollen grains. The results showed that P. peruviana pollen grains are isopolar, radial, prolato-spheroidal in shape and medium in size. There was also an increase in pollen grain area when cultivated in shading with white shade net and in full sun. [ABSTRACT FROM AUTHOR]
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- 2019
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10. Avaliação do padrão de qualidade microscópica em amostras comerciais de achocolatados.
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Câmara Januário, Andressa Carvalho, Medeiros Assis, Nadinne, Ribeiro Ruback, Camilla, Almeida Nery, Ivanilton, and Alexandre Marques, Carlos
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COCOA products ,SCANNING electron microscopes ,FRAUD ,MICROSCOPY ,CHEMICAL elements ,COCOA ,CACAO beans - Abstract
Copyright of Segurança Alimentar e Nutricional is the property of Universidade Estadual de Campinas - Portal de Periodicos Eletronicos Cientificos and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
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- 2021
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11. The fingerprint of imperial topaz from Ouro Preto region (Minas Gerais state, Brazil) based on cathodoluminescence properties and composition.
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Gauzzi, Teodoro, Graça, Leonardo Martins, Lagoeiro, Leonardo, de Castro Mendes, Isolda, and Queiroga, Gláucia Nascimento
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CATHODOLUMINESCENCE , *INDUCTIVELY coupled plasma mass spectrometry , *ELECTRON probe microanalysis , *RAMAN spectroscopy , *SCANNING electron microscopes , *LASER ablation , *OPTICAL microscopes - Abstract
A study of the cathodoluminescence (CL) properties of imperial topaz from Ouro Preto region (Minas Gerais state, Brazil) and its relation with trace-element composition was conducted, using scanning electron microscope cathodoluminescence (SEM-CL), optical microscope cathodoluminescence (OM-CL), cathodoluminescence-spectrometry (CL-spectrometry), electron microprobe analysis (EMPA), laser ablation inductively-coupled plasma mass spectrometry (LA-ICP-MS) and Raman spectrometry. Each analytical technique allowed characterization of the imperial topaz fingerprint. SEM-CL panchromatic images show different crystal growth and resorption events in imperial topaz crystals. Colour CL images indicate only blue to violet emissions. The CL-spectra indicate a broad emission band with low intensity peak at ~417 nm and a broad emission band with high intensity and major peaks at 685, 698, 711 and 733 nm. The EMPA indicates high OH content, in which the OH/(OH + F) ratio ranges between 0.35–0.43 (0.72 ≤ OH ≤ 0.86 apfu). High Cu and Zn concentrations (LA-ICP-MS) were measured in the high luminescence areas of SEM-CL images, suggesting both elements as CL-activators in imperial topaz. Raman and CL-spectra indicate high Cr concentrations, corroborated by EMPA and LA-ICP-MS results. The high Cr caused strong luminescence intensities that enabled their superimposition over the OH stretching mode (~3650 cm–1) of topaz in all Raman spectra. Among trace elements, the concentrations of Ti, V, Cr, Mn, Fe, Cu, Zn, Ga and Ge provide the fingerprint of imperial topaz. [ABSTRACT FROM AUTHOR]
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- 2018
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12. Small but not trivial: Nothostigma sepeensis sp. nov., a lycopsid from the Cisuralian (early Permian) of the Paraná Basin, Brazil.
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Spiekermann, Rafael, Jasper, André, Pozzebon-Silva, Ândrea, Carniere, Júlia Siqueira, Benício, José Rafael W., Guerra-Sommer, Margot, and Uhl, Dieter
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SCANNING electron microscopes ,GONDWANA (Continent) - Abstract
This study deals with lycopsid axes from Cisuralian strata of the São Sepé outcrop in southern Brazil, belonging to the Glossopteris flora. Their gross morphology is described using standard palaeobotanical techniques. They lack cuticles, but the description is complemented using vinyl polysiloxane replicas of their leaf cushions, which reveal imprints of their epidermal features under the scanning electron microscope. The specimens are distinct from other lycopsid fossil-taxa found so far in Permian post-glacial strata including elements of the Glossopteris flora. They resemble Nothostigma Doweld, a common fossil-genus of lycopsids that flourished in Gondwana during the Mississippian pre-glacial stage. Based on their morphology, we propose the new fossil-taxon Nothostigma sepeensis sp. nov., increasing the knowledge of the so far often neglected lycopsid diversity from the Permian of Gondwana. •Description of lycopsid fossils from Cisularian strata of Brazil belonging to the Glossopteris flora. • The specimens are distinct from other lycopsid fossil-genera from the Gondwanan Glossopteris flora. • The fossils resemble lycopsids that flourished in Gondwana during a Mississippian pre-glacial stage. • The new fossil-taxon Nothostigma sepeensis sp. nov. Is proposed. [ABSTRACT FROM AUTHOR]
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- 2023
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13. Holocene vegetation, climate, sea-level oscillation, and human impact inferred from the archaeological site Cabeludo in Maranhão State, NE Brazil.
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de Moraes, Caio Alves, da Costa, Marcondes Lima, Navarro, Alexandre Guida, Negrão, Leonardo Boiadeiro Ayres, da Silva Valente, Glayce Jholy Souza, Pöllmann, Herbert, and Behling, Hermann
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ARCHAEOLOGICAL excavations , *MANGROVE plants , *HOLOCENE Epoch , *X-ray powder diffraction , *MARINE transgression , *SCANNING electron microscopes , *RUNOFF - Abstract
This study provides an environmental reconstruction of an archaeological site in the northern part of northeastern Brazil. To understand how the climate, relative sea-level (RSL), and human activities triggered environmental changes in Maranhão State during the Holocene, a multi-proxy analysis has been done in a 450 cm long sediment core. The core has been radiocarbon dated and analyzed by its content of pollen, spores, micromorphological and spot chemical analyzes by Scanning Electron Microscope (SEM), multi-element chemical analyzes, X-ray Powder Diffraction (XRD), charcoal, Loss on Ignition (LOI), and sedimentary characteristics. The site was a tidal channel, part of an estuarine system surrounded by mangrove vegetation between 7920 and 7500 cal yr BP. For this period, the mineralogical and chemical composition showed sediments inputs also coming from marine sources, indicating a transgression of the ocean. The combination of marine transgression and dry environmental conditions allowed mangroves to colonize areas further inland. From 7500 to 1800 cal yr BP, the study site turned into the current freshwater tributary river surrounded by lowlands arboreal and herbaceous vegetation while the Amazon biome expanded. The moister conditions and the RSL regression displaced the mangroves to the current coastal bays about 120 km to the north. The sediment run-off was predominantly continental, as showed by mineralogical and chemical analysis. After 1800 cal yr BP, human influence is noted by increased charcoal and fragmented ceramics in the sediment. Archaeological studies at this region showed that Amerindians built stilt-house villages upon the rivers and lakes, which played stronger role in the environment. These pre-colonial stilt-houses Maranhão lowland are the only ones found South America. • ∼8000 years of environmental dynamics in the coastal northern NE Brazil. • Mangrove dynamics as a consequence of sea level and climate changes in Maranhão State. • Palaeoecological study developed in archaeological site in northern NE Brazil. • Human stilt house community and their influence on the environment in South America. [ABSTRACT FROM AUTHOR]
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- 2022
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14. Bioaccumulation of potentially toxic elements in Ammonia tepida (foraminifera) from a polluted coastal area.
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Castelo, Wellen F.L., Alves Martins, Maria Virginia, Martínez-Colón, Michael, da Silva, Layla C., Menezes, Celma, Oliveira, Thales, Helena de M Sousa, Silvia, Aguilera, Orangel, Laut, Lazaro, Laut, Vanessa, Duleba, Wânia, Frontalini, Fabrizio, Bouchet, Vincent M.P., Armynot du Châtelet, Eric, Francescangeli, Fabio, Geraldes, Mauro C., Reis, António T., and Bergamashi, Sérgio
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POISONS , *MARINE food chain , *PALEOENVIRONMENTAL studies , *BIOACCUMULATION , *SCANNING electron microscopes , *MERCURY , *BIOINDICATORS - Abstract
This work documents the presence of potentially toxic elements (PTEs) in the sediment and in tests of Ammonia tepida, one of the most common benthic foraminifera species in coastal environments worldwide. It aims to analyze if the presence of PTEs in the carbonate test of this species is related to metals concentration in the sediment aiming its application in paleoenvironmental studies. Three chambers of fifty A. tepida specimens from contaminated and uncontaminated sediments from the Sepetiba Bay, one of the most polluted coastal systems from the SE Brazil, were analyzed using an Environmental Scanning Electron Microscope coupled with an X-ray Dispersive Energy Spectrometer. The results reveal the presence of lithogenic elements and PTEs in the tests of A. tepida. Relatively high values of Pb, Hg and Sn were found in specimens recovered from both polluted and unpolluted sediment layers. The bioaccumulation index revealed higher enrichment of Cd and Cr in tests from sediments moderately to heavily polluted by Cd and to a lesser extent by Cr. The results suggest that the incorporation of metals might be controlled and affected by several factors, such as the water residence time, availability of the metals, and biogeochemical processes. As a result, applications of this method utilizing A. tepida for paleoenvironmental studies do not appear to be feasible without further research. • Environmental stressors, namely pollution by potentially toxic elements (PTEs). • Concentration of PTEs in the sediment and in Ammonia tepida tests. • Complex relationship between the PTEs present in the sediment and A. tepida tests. • Ammonia tepida accumulates PTEs that could be transferred through marine food chains. [ABSTRACT FROM AUTHOR]
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- 2022
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15. From the micromorphology of paleoweathering fronts to paleoenvironmental analysis: A case study of the Cretaceous dune fields of Sanfranciscana Basin, Brazil.
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Nascimento, Diego Luciano, Martinez, Pedro, Batezelli, Alessandro, Ladeira, Francisco, and Corrêa, Leticia
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SEDIMENTARY structures , *PARTICLE size distribution , *SCANNING electron microscopes , *X-ray fluorescence , *SAND dunes - Abstract
[Display omitted] • Weathering pattern is mainly determined by the bimodality of aeolian deposits. • Dissolution features and booklets of kaolinite reveal monosiallitisation process. • Kaolinization processes suggest an increase in moisture between Albian and Cenomanian. The work investigated the paleoenvironmental significance of kaolinite-rich weathering fronts developed during the Cretaceous in stabilized dune fields of Sanfranciscana Basin in Brazil. To this, was conducted a multi-scale analysis from the outcrops of paleosols to mineral grains and soil pores. The macro and micromorphology of paleoweathering fronts allow recognizing weathering features and estimating the porosity and hydraulic parameters (permeability, capillary pressure, and saturated hydraulic conductivity). Scanning electron microscope analyses were conducted to investigate surface microtextures of quartz grains for weathering process characterization based on dissolution microfeatures. Energy-dispersive X-ray spectrometry was utilized to identify chemical elements of clay minerals. The major and trace elements were analyzed using a Philips X-ray fluorescence (XRF) spectrometer (PW 2440). Our results showed that weathering fronts expand through preferential water paths (pipe and finger flow) in bedding planes in response to textural and porosity contrasts related to the bimodality (i.e., the difference of grain size distribution between overlapped sedimentary structures) of aeolian deposits. The dissolution features present in quartz grains, such as etching, pitting, total dissolution of grains, iron coatings, and booklets of well-developed kaolinite, reveal an increase in humidity and the pedogenetic kaolinization process typical of a humid tropical environment. These weathering patterns coincide with cooling events between the Albian and the Cenomanian report in the literature. Our study indicates that during the Cretaceous, the Sanfransicana Basin underwent climatic amelioration and a rise in water table level, which likely enhanced dune stabilization and the formation of an extensive geomorphic surface. [ABSTRACT FROM AUTHOR]
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- 2022
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16. The role of biological agents in the microstructural and mineralogical transformations in aluminium lateritic deposit in Central Brazil.
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de Oliveira, Fábio Soares, Varajão, Angélica Fortes Drummond Chicarino, Varajão, César Augusto Chicarino, Schaefer, Carlos Ernesto Gonçalves Reynaud, and Boulangé, Bruno
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MICROSTRUCTURE , *SOIL mineralogy , *ALUMINUM in soils , *SCANNING electron microscopes , *PETROLOGY - Abstract
Abstract: Petrological studies using X-ray diffraction (XRD) and micromorphological analyses (Optical Microscopy and SEM), were done to understand the role of biological activity in the evolution of Barro Alto bauxite. The results indicated that this influence came through structural (or microstructural) and mineralogical transformations, namely: I — the bioturbation caused by termites and II — the mechanical degradation and geochemical transformation promoted by roots. In the bioturbation caused by termites were formed: I — a intergrain micro-aggregate structure, characterised by gibbsite crystals from isalteritic bauxite fragmentation on the bottom of the profile and II — a granular structure characterised by a termitic microaggregates with fragments of gibbsite immersed in a kaolinite–gibbsite–goethite–boehmite micromass, formed by bioturbation of the degradation clay with nodules of gibbsite, whose origin is the geochemistry degradation of isalteritic bauxite. The processes associated with geochemical and mechanical degradation caused by roots were responsible for the genesis of: I — a porphyric texture with bauxite fragments surrounded by nonaggregate material and II — fine monic structure where the gibbsite neoformation has the mould cavities left by old roots, generating riziform features. [Copyright &y& Elsevier]
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- 2014
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17. Characterization of the physicochemical and thermal properties of unexplored starches with potential industrial uses from six Brazilian maize landraces.
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Raguzzoni, Josiane Callegaro, Lopes da Silva, José A., Maraschin, Marcelo, and Delgadillo, Ivonne
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STARCH , *CORN , *CRYSTALLINITY , *AMYLOPLASTS , *SCANNING electron microscopes , *GELATION , *THERMAL properties - Abstract
Starches isolated from six maize landraces from Brazil were investigated for their physicochemical, morphological, structural and thermal properties and compared to a commercial maize starch (COM). Similarities (chemical composition) and differences (structural characteristics) were observed. The crystallinity of starches ranged between 18.5 and 25.0%. The swelling power at 65°C ranged between 3.00 g/g Pires (PIR) and 4.82 g/g Mato Grosso (MT), whereas at 90°C varied between 18.8 g/g (PIR) and 23.9 g/g (MT), differing from COM, i.e., 14.6 g/g. The starch granule's morphology and size determined by SEM showed polyhedral and spherical shapes and a heterogeneous size distribution between 1.7 and 25 µm. The gelatinization process studied by DSC showed that transition temperatures ( T0, Tp, Tc) ranged between 61.0-65.9, 67.5-71.7, and 75.2-76.8°C, respectively, and enthalpies (Δ Hgel) between 11.4 and 13.3 (J/g). The retrogradation properties were analyzed after storage for 7, 14, and 40 days at 4°C; the retrogradation degree changed with the time and among the different starches, as well as the transition temperatures and enthalpies, which were lower than those observed for the gelatinization process. Other parameters like gelatinization and retrogradation temperature range ( Rgel, Rret) and PHI were analyzed. Rgel was faster for BR and slower for MT, while Rret was broader than the corresponding gelatinization and PHI was not significantly different among the studied starches, except for the BR (slightly higher value). [ABSTRACT FROM AUTHOR]
- Published
- 2013
- Full Text
- View/download PDF
18. Description of Eggs of Anastrepha curitis and Anastrepha leptozona (Diptera: Tephritidae) Using SEM.
- Author
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DUTRA, VIVIAN S., RONCHI-TELES, BEATRIZ, STECK, GARY J., and SILVA, JANISETE G.
- Subjects
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ANASTREPHA , *FRUIT flies , *SCANNING electron microscopes , *EGGS - Abstract
Egg morphologies of Anastrepha curitis Stone and Anastrepha leptozona Hendel are described using scanning electron microscopy. Eggs were dissected from females captured in McPhail traps in Manaus and Presidente Figueiredo in the state of Amazonas, Brazil. Eggs of A. curitis are very long and have no aeropyles but show a seemingly porous surface on the anterior pole. Eggs of A. leptozona are robust. Eggs of both species are smooth and have no chorion ornamentation, reticulation, or protuberances. The micropyle is located at the apex of the anterior pole of the egg for both species studied. No distinct respiratory horn was detected either in A. curitis or A. leptozona. Diagnostic characters include egg length and presence versus absence of a porous surface on the anterior pole. [ABSTRACT FROM AUTHOR]
- Published
- 2013
- Full Text
- View/download PDF
19. Phenotypic and genotypic characterization of Aeromonas jandaei involved in mass mortalities of cultured Nile tilapia, Oreochromis niloticus (L.) in Brazil.
- Author
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Assane, Inácio Mateus, de Sousa, Elielma Lima, Valladão, Gustavo Moraes Ramos, Tamashiro, Geovana Dotta, Criscoulo-Urbinati, Eduardo, Hashimoto, Diogo Teruo, and Pilarski, Fabiana
- Subjects
- *
NILE tilapia , *PHENOTYPES , *SCANNING electron microscopes , *GENOTYPES , *AEROMONAS , *OXYTETRACYCLINE , *AQUAPONICS - Abstract
Aeromonas jandaei is an emerging fish pathogen associated with massive mortalities in cultured freshwater fish. This study investigated the morphological, biochemical, molecular, virulence, pathogenicity, and antimicrobial susceptibility characteristics of four strains of A. jandaei involved in the occurrence of mass mortalities of cultured Nile tilapia in an earthen pond farm and laboratory fibreglass tanks in Brazil. Isolates were identified by morphological, biochemical, and molecular analyses. Bacteria morphology was assessed under light and scanning electron microscopes, biochemical profile by conventional biochemical tests, and molecular identification by nucleotide sequencing and phylogenetic analysis of the highly conserved 16S rRNA gene, as well as the housekeeping genes, gyrB , and rpoB. The virulence and pathogenicity were confirmed by screening for 12 virulence genes and induced experimental infection. Broth microdilution method was used to assess susceptibility to enrofloxacin, florfenicol, oxytetracycline, and thiamphenicol. All isolates were confirmed as A. jandaei. Haemolysin, temperature-sensitive protease, haemolysin-aerolysin, and nuclease were the most predominant virulence genes. Lateral flagella B and cytolytic enterotoxin/cytotonic enterotoxin were only detected in strains isolated from fish from fibreglass tanks. In the experimental challenge, doses above 4.3 × 107 CFU mL−1 resulted in mass mortality (100%) in a short period (less than 12 h) without remarkable external clinical signs. Typical clinical signs of disease, including lethargy, inappetence, surface swimming, exophthalmia, cloudy eyes, haemorrhagic patches, and redness of the skin, below the opercula, and at the base of all fins, fin rot, and pale body surface were observed in fish challenged with doses below 4.0 × 107 CFU mL−1 (10–100% mortality). The most predominant histopathological changes in the internal organs of diseased fish were melano-macrophage centres, vascular congestion with thrombus, haemorrhage, and necrosis. Strains isolated from fish from the earthen pond farm were resistant to oxytetracycline, while the strains from fibreglass tanks were sensitive to all antimicrobials. This study provides pertinent data on A. jandaei host-pathogen interactions, susceptibility to antimicrobials, morphological, biochemical, and molecular characteristics, and geographical distribution, which may serve as a guideline for A. jandaei isolation and identification in aquaculture. • The multilocus phylogenetic analysis allowed to clarify the phylogenetic relationships of the clinical isolates. • This is the first detailed report of mass mortality caused by Aeromonas jandaei in Brazil. • Florfenicol (10 mg kg−1 bw) and Oxytetracycline (120 mg kg−1 bw) were ineffective to control the outbreak in the fish farm. • A. jandaei killed 100% of fish in less than 12 h without remarkable clinical signs. • Haemolysin, temperature-sensitive protease, haemolysin-aerolysin and nuclease were detected in all clinical isolates. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
20. Experimental investigation of needles, syringes and techniques for intravitreal injections.
- Author
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De Stefano, Vinicius S, Abechain, Jose JK, de Almeida, Luiz FS, Verginassi, Diego M, Rodrigues, Eduardo B, Freymuller, Edna, Maia, Maurício, Magalhaes, Octaviano, Nguyen, Quan D, and Farah, Michel E
- Subjects
- *
ENUCLEATION of the eye , *DRUG administration , *SCANNING electron microscopes , *INJECTIONS , *SYRINGES - Abstract
To assess the techniques and materials used in intravitreal injections. Descriptive study realized at the Vision Institute of the Federal University of São Paulo, Brazil. Different brands of needles and syringes, as well as enucleated porcine eyeballs. The ultra-structures of commonly used needles were analysed by scanning electron microscope, and they were compared using different criteria, such as irregularities and debris from the lubrication process. The scleral incision was also assessed using needles of different brands and sizes. Accuracies in drug administration were studied by comparing the residual and delivered volume of needles and also by the analysis of reflux after intravitreal injections. Efficiency and quality of materials used in intravitreal injections. Ultra-structure analyses showed that all needles had different types of irregularities. Some photographs showed debris from the lubrication process, especially in BD needles. Scleral incision analysis showed a tendency of reducing the ocular damage with increasing gauge ( P = 0.024). The investigation of delivery accuracy showed that almost all needles underdosed the amount injected ( P < 0.05), and that the reflux could be minimized by tunnelled injections with thinner needles. Needles used in intravitreal injections possess many irregularities in their structures, which may cause different injection outcomes. Analyses of scleral incisions showed that the larger the needle gauge, the lesser the scleral damage and the risk of complications. Moreover, drug administration inaccuracies might be one of the causes for some unsuccessful attempts of treatment. [ABSTRACT FROM AUTHOR]
- Published
- 2011
- Full Text
- View/download PDF
21. The Infection Process of Pestalotiopsis Longisetula Leaf Spot on Strawberry Leaves.
- Author
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Rodrigues, Fabrício A., Silva, Ivanete Tonole, Antunes Cruz, Maria Fernanda, and Carré‐Missio, Vivian
- Subjects
- *
PHYTOPATHOGENIC microorganisms , *PESTALOTIA , *STRAWBERRIES , *LEAF spots , *TRACHEARY cells , *FRUIT rots , *SCANNING electron microscopes - Abstract
Pestalotia leaf spot, caused by the fungus Pestalotiopsis longisetula Guba, has become the major disease affecting strawberry production in Brazil. Strawberry seedlings with 4-5 leaves were inoculated with a conidial suspension of P. longisetula (2 × 105 conidia/ml), and leaf samples were collected at 48, 72, 96 and 144 h after inoculation (hai) for observation in the scanning electron microscope. Conidia germinated within 48 hai. At 72 hai, conidia had formed very long germ tubes over the epidermal cells without any evidence of appressorial formation nor direct penetration. At 96 hai, fungal hyphae grew inter- and intracellularly in the lacunous parenchyma and also through tracheary elements. Pycnidia were first observed on the leaf surface at 96 hai. At 144 hai, conidia of P. longisetula were first liberated from the pycnidia. This study adds new information to better understand of the infection process of P. longisetula that may help in developing more effective disease control strategies. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
- View/download PDF
22. Proposal for an Environmentally Sustainable Beneficiation Route for the Amphibolitic Itabirite from the Quadrilátero Ferrífero-Brazil.
- Author
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Gonçalves, Gizele Maria Campos and Lima, Rosa Malena Fernandes
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IRON ores , *SCANNING electron microscopes , *MICROSCOPY , *SCANNING electron microscopy , *GOETHITE , *MAGNETITE , *QUARTZ , *HEMATITE - Abstract
The high world demand for iron ores opposed to the rapid exhaustion of high-grade deposits from the main producing regions around the world has motivated the search and/or improvement of beneficiation routes, which enable the economic use of iron formations previously considered marginal ores, which have the potential to considerably increase mineable reserves due to their large volume. In this study, a sample of amphibolitic itabirite from the eastern region of the Quadrilátero Ferrífero, Minas Gerais, Brazil was characterized, aiming at its use in the industrial pelletizing circuit. The main physical characteristics of this ore are moisture = 10% and specific weight = 3710 kg/m3. The ore has a high grade of loss on ignition—LOI (6.7%) and P (0.14%). Through X-ray diffractometry (XRD), optical microscopy and scanning electron microscope—SEM, the ore was found to consist of 64.5% goethite (amphibolitic, alveolar, massive and earthy); 6.8% hematite (martitic, granular and lamellar) and 0.9% magnetite. The main gangue mineral is quartz (25.5%). Based on the results of concentration tests (magnetic and flotation) performed with the studied sample, the magnetic concentration route of deslimed sample followed by the addition of slimes in magnetic concentrate can be incorporated into the pelletizing process. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
23. Micrometric characterization of implant surfaces of the five largest companies in the Brazilian market. Part II: Biomet 3i BoneLike implants.
- Author
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ROSA, Márcio Borges, ALBREKTSSON, Tomas, FRANCISCHONE, Carlos Eduardo, SCHWARTZ FILHO, Humberto Osvaldo, and WENNERBERG, Ann
- Subjects
DENTAL implants ,DENTURES ,ORAL surgery ,SCANNING electron microscopes ,ELECTRON microscopes - Abstract
Introduction: The quality of the bone-implant interface is directly influenced by implant surface roughness and a roughness average, with the Sa between 1 to 2μm, has demonstrated better clinical and laboratory results. In Brazil, are installed more than two million implants per year, where 79% are manufactured by domestic companies. However, very little is known or published about the characterization of surfaces of these implants, on the micrometer level. Objective: The aims of this study are to evaluate and characterize numerically the surface of the implants BoneLike, of Biomet 3i do Brasil company, one of the five largest companies in the Brazilian market. Methods: Were evaluated a total of 6 implants, purchased directly on the market, of two different designs (BoneLike-HE and BoneLike-CM) and different batches, using light interferometry. Were performed 9 measurements randomly chosen for each unit, 3 on the tops, 3 on the valleys and 3 on the flanks of the threads. The same pattern was followed for evaluation by scanning electron microscope. Results: The analyzed implants from this company showed S
a values of 0.47μm for BoneLike-HE and 1.01μm for BoneLike-CM. Comparing the batches, both designs showed statistically significant differences between them. Conclusions: The roughness values found herein categorize the surfaces of BoneLike-HE implants as smooth, and BoneLike-CM implants as moderately rough, with Sa values quite close to a smooth surface. [ABSTRACT FROM AUTHOR]- Published
- 2012
24. Micrometric characterization of implant surfaces of the five largest companies in the Brazilian market. Part I: Neodent implants.
- Author
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ROSA, Marcio Borges, ALBREKTSSON, Tomas, FRANCISCHONE, Carlos Eduardo, SCHWARTZ FILHO, Humberto Osvaldo, and WENNERBERG, Ann
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DENTAL implants ,ARTIFICIAL implants ,INTERFEROMETERS ,SCANNING electron microscopes ,ELECTRON microscopes - Abstract
Introduction: The quality of the bone-implant interface is directly influenced by implant surface roughness and a roughness average, with the Sa between 1 to 2 μm, has demonstrated better clinical and laboratory results. In Brazil, are installed more than two million implants per year, where 79% are manufactured by domestic companies. However, very little is known or published about the characterization of surfaces of these implants, on the micrometer level. The aims of this study are to evaluate and characterize numerically the surface of the implants of Neodent company, one of the five largest companies in the Brazilian market. Methods: Were evaluated a total of 9 implants, purchased directly on the market, of 3 different designs and different batches of the company, using a light interferometer. Were performed 9 measurements randomly chosen for each unit, 3 on the tops, 3 on the valleys and 3 on the flanks of the threads. The same pattern was followed for evaluation by scanning electron microscope. Results: In general, implants analyzed in this company, showed Sa values of 0.75 μm, 0.67 μm and 0.65 μm, respectively, for each design. Comparing the batches, all designs presented statistically significant differences between at least one batches in relation to other. Conclusions: The roughness values found, classify the surfaces of the three implants evaluated as minimally rough. [ABSTRACT FROM AUTHOR]
- Published
- 2012
25. Morphology and ecology of Thalassiosira Cleve (Bacillariophyta) species rarely recorded in Brazilian coastal waters.
- Author
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Garcia, M. and Odebrecht, C.
- Subjects
THALASSIOSIRA ,PHYTOPLANKTON ,MICROSCOPES ,SCANNING electron microscopes ,COASTS ,ESTUARIES - Abstract
Copyright of Brazilian Journal of Biology is the property of Instituto Internacional de Ecologia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2009
- Full Text
- View/download PDF
26. Diatom Epibionts on Amphipod Crustaceans: A Possible Vector for Co-introductions?
- Author
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Desiderato, Andrea, Beermann, Jan, Haddad, Maria Angelica, and Fernandes, Luciano Felicio
- Subjects
AMPHIPODA ,DIATOMS ,CRUSTACEA ,INTRODUCED species ,SCANNING electron microscopes ,ECOSYSTEMS - Abstract
Epibiotic associations can result in co-introductions of non-indigenous species, which may affect ecosystems in several ways. In fouling communities of three estuaries in southern Brazil, a number of amphipods was found to harbour a dense coverage of epibionts. Three different species, the two globally widespread caprellids Caprella equilibra and Paracaprella pusilla, as well as the ischyrocerid Jassa valida, had been colonised by diatoms. Further scanning electron microscope analyses assigned these diatoms to 14 different species that had previously been reported from benthic habitats. This is one of the scarce records of diatoms attached to amphipods. The occurrence of the diatom Amphora helenensis represents the first report for Brazilian waters as well as the second record for the whole SW Atlantic Ocean. As some diatoms were associated with common fouling amphipods, a possible regional spread aided by these crustaceans seems likely. Possible effects of this amphipod-diatom association on the animals and their implications for the underlying ecosystems of this remain to be elucidated. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
27. Remarkable fossil crickets preservation from Crato Formation (Aptian, Araripe Basin), a Lagerstätten from Brazil.
- Author
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Dias, Jaime Joaquim and Carvalho, Ismar de Souza
- Subjects
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MICROBIAL mats , *INSECT collection & preservation , *FOSSILS , *SCANNING electron microscopes , *ALIMENTARY canal , *OVARIAN follicle , *ZYGAPOPHYSEAL joint - Abstract
The paleoentomofauna recorded in the Crato Formation laminated limestones (Araripe Basin, Aptian) represents one of the most important Konservat-Lagerstätten deposits globally documented. Among the insects, the high morphological fidelity, abundance and diversity of the Grylloidea superfamily allows a more refined study of the external and internal cuticular morpho-anatomical features and preserved soft tissues. Scanning electron microscope analysis with coupled energy dispersion x-ray spectroscopy (SEM/EDS) show that the carcasses of the grylloids are predominantly replaced by three distinct mineral phases with occurrence of features hardly preserved in the fossil record such as the ommatidia's polygonal facets of compound eyes, cuticular layers differentiation (epi and procuticle), internal anatomical microstructures of digestive tract, ovarian fragments, eggs, and visceral and locomotor muscle tissues. The identification of significant microbial evidence associated with the cricket's carcasses allow us to interpret that the main factor responsible for the exceptional cricket's preservation is the influence of microbial mats in the fossilization process. Image 1 • We analyzed 178 specimens of fossil crickets from the Lagerstätten Crato Formation (Aptian), Araripe Basin, Brazil. • Morpho-anatomical features of the compound eyes, cuticle, digestive tract, muscles, ovaries and eggs were preserved. • The carcasses are predominantly replaced by three distinct mineral phases. • The main factor responsible for the exceptional preservation of these insects is the influence of microbial mats. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
28. "Medusa quartz" with gilalite inclusions.
- Author
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Rondeau, Benjamin and Macri, Michele
- Subjects
- *
QUARTZ inclusions , *X-ray diffraction , *X-ray diffractometers , *ANALYTICAL chemistry , *X-ray spectroscopy , *SCANNING electron microscopes - Abstract
The article discusses the gemological properties of the medusa quartz with gilalite inclusions found in Paraíba State, Brazil in August 2004. The stone exhibited jelly fish-like inclusions which were identified using an Inel CPS 120 X-ray powder diffractometer with a curved detector, combined with a Gandoli single-crystal camera and copper Kα1 emission. Chemical analysis using a Jeol JSM 840A scanning electron microscope equipped with an Oxford Link energy-dispersive detector revealed that the acicular and jelly fish-like inclusions contained silicon and copper.
- Published
- 2005
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