Projeto de sistema de informação para o laboratório de microbiologia agrícola e ambiental da Embrapa Clima Temperado.

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Corrosion behavior of dental implants immersed into human saliva: Preliminary results of an in vitro study

Over the years, dif- ferent implant surfaces have been used to try to maximize bone to implant contact. The aim of this study was to compare levels of metallic ions and particles dissolution collected from two dif- ferent dental implants surfaces immersed into human saliva. PATIENTS AND METHODS: A total of 60 den- tal implants were tested. Group A: sanded with aluminium oxide medium grade particles and ac- id-etched; Group B: micro-sanded with calcium phosphate powders and acid-etched. Forty im- plants were immersed in 20 ml of human saliva, twenty, as a control, in sterile saline solution. ICP-MS was performed to detect any metallic ions released from dental implants at T0, on day 1 (T1), on day 3 (T2), after one week (T3), on day 14 (T4), after 3 months (T5) and after 6 months (T6). RESULTS: Dissolution of metallic particles of titanium and nickel, absent in human saliva (T0), were found after one week (T3) for Group B and after 3 months (T5) for Group A. Vanadium was already detected in small concentrations in either group after 1 day, with an exponential growth for Group B. CONCLUSIONS: Preliminary results reported signi cant values of Ti, Ni and V released by Group B, showing for the rst time statistically signi cant values of vanadium

Time walkers and spatial dynamics of ageing information

The distribution of information is essential for living system's ability to coordinate and adapt. Random walkers are often used to model this distribution process and, in doing so, one effectively assumes that information maintains its relevance over time. But the value of information in social and biological systems often decay and must continuously be updated. To capture the spatial dynamics of ageing information, we introduce time walkers. A time walker moves like a random walker, but interacts with traces left by other walkers, some representing older information, some newer. The traces forms a navigable information landscape. We quantify the dynamical properties of time walkers moving on a two-dimensional lattice and the quality of the information landscape generated by their movements. We visualise the self-similar landscape as a river network, and show that searching in this landscape is superior to random searching and scales as the length of loop-erased random walks

Aptidão agrícola das terras do Campo Experimental dos Cerrados da Embrapa Amapá, Estado do Amapá.

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From time-series to complex networks: Application to the cerebrovascular flow patterns in atrial fibrillation

A network-based approach is presented to investigate the cerebrovascular flow patterns during atrial fibrillation (AF) with respect to normal sinus rhythm (NSR). AF, the most common cardiac arrhythmia with faster and irregular beating, has been recently and independently associated with the increased risk of dementia. However, the underlying hemodynamic mechanisms relating the two pathologies remain mainly undetermined so far; thus the contribution of modeling and refined statistical tools is valuable. Pressure and flow rate temporal series in NSR and AF are here evaluated along representative cerebral sites (from carotid arteries to capillary brain circulation), exploiting reliable artificially built signals recently obtained from an in silico approach. The complex network analysis evidences, in a synthetic and original way, a dramatic signal variation towards the distal/capillary cerebral regions during AF, which has no counterpart in NSR conditions. At the large artery level, networks obtained from both AF and NSR hemodynamic signals exhibit elongated and chained features, which are typical of pseudo-periodic series. These aspects are almost completely lost towards the microcirculation during AF, where the networks are topologically more circular and present random-like characteristics. As a consequence, all the physiological phenomena at microcerebral level ruled by periodicity - such as regular perfusion, mean pressure per beat, and average nutrient supply at cellular level - can be strongly compromised, since the AF hemodynamic signals assume irregular behaviour and random-like features. Through a powerful approach which is complementary to the classical statistical tools, the present findings further strengthen the potential link between AF hemodynamic and cognitive decline.Comment: 12 pages, 10 figure

Antiparasitic activity of chicory (Cichorium intybus) and its natural bioactive compounds in livestock: a review

Increasing drug resistance in gastrointestinal (GI) parasites of livestock and concerns about chemical residues in animal products and the environment are driving the development of alternative control strategies that are less reliant on the use of synthetic drugs. An increasingly investigated approach is the use of bioactive forages with antiparasitic properties as part of the animal’s diet (nutraceuticals) or as potential sources of novel, natural parasiticides. Chicory (Cichorium intybus) is a multi-purpose crop and one of the most promising bioactive forages in temperate regions, and numerous in vivo trials have explored its potential against parasitic nematodes in livestock. However, it is unclear whether chicory can induce a direct and broad activity against various GI parasites in different livestock species, and the levels of chicory in the diet that are required to exert an efficient antiparasitic effect. Moreover, the mechanisms leading to the reported parasiticidal activity of chicory are still largely unknown, and its bioactive phytochemicals have only recently been investigated. In this review, we summarise the progress in the study of the antiparasitic activity of chicory and its natural bioactive compounds against GI parasites in livestock, through examination of the published literature. The available evidence indicates that feeding chicory can reduce faecal egg counts and/or worm burdens of abomasal nematodes, but not infections with intestinal worms, in ruminants. Highly chicory-rich diets (≥ 70% of chicory dry matter in the diet) may be necessary to directly affect abomasal parasitism. Chicory is known to synthesise several bioactive compounds with potential antiparasitic activity, but most research has been devoted to the role of sesquiterpene lactones (SL). Recent in vitro studies have confirmed direct and potent activity of SL-rich extracts from chicory against different GI helminths of livestock. Chicory SL have also been reported to exhibit antimalarial properties and its potential antiprotozoal activity in livestock remains to be evaluated. Furthermore, the detailed identification of the main antiparasitic metabolites of chicory and their pharmacokinetics need further confirmation. Research gaps and perspectives on the potential use of chicory as a nutraceutical forage and a source of bioactive compounds for parasite control in livestock are discussed

Levantamento de reconhecimento de alta intensidade dos solos do município de Ariquemes, Estado de Rondônia.

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Natural attenuation processes in AMD context by mineralogical control: iron oxyhydroxides, oxyhydroxysulfates, and efflorescent sulfates

Acid mine drainage (AMD) is a common problem associated with the weathering of metal sulfide wastes in abandoned mining areas, which can be rich in toxic metals and metalloids. Oxidative dissolution of these minerals may negatively affect the soils and water reservoirs nearby. The formation of secondary mineral phases such as iron oxyhydroxides, oxyhydroxysulfates, and efflorescent sulfates may be a natural attenuation process in these areas because these minerals can scavenge potentially toxic elements. Typically formed by the evaporation (efflorescent salts) or precipitation (ochreous iron-rich oxyhydroxides) these minerals are highly soluble and reactive. Therefore, their characterization and inventory are particularly important for predicting the cycles of retention/contamination or accumulation zones of potential toxic elements (PTE) and acidity in mining contaminated systems. The abandoned mines of Valdarcas and São Domingos were selected for the present study due to their AMD signature and occurrence of some of these secondary minerals. Valdarcas (north of Portugal) is a W-mine associated with a skarn deposit with sulfides that has already been rehabilitated. However, the AMD problems remain in the watercourse that receives leachates from the waste dumps. São Domingos is a Cu-mine composed of massive sulfide deposits that belong to the Iberian Pyrite Belt (south of Portugal). This mining area, which is presently under remediation process, is highly contaminated and AMD is a longlasting problem. The samples collected in these mining areas were characterized by their morphology, size, mineralogy, and chemical composition using different techniques: binocular microscopy, SEM-EDS, TEM, BET, DRX, FTIR, and XPS. In Valdarcas mine area, typical ochreous phases such as schwertmannite and goethite were identified as the dominant secondary phases. These brownish-yellow ferric amorphous and poorly crystalline minerals with high surface area (125 mg2 /m) can remove PTE via adsorption processes, contributing to their retention in the mining environment. In contrast, at São Domingos, efflorescent sulfate salts are more abundant. Melanterite and copiapite were the prevailing salts identified. With different morphologies, these minerals are highly soluble and therefore play a relevant key in the retention/mobilization cycles of hazardous contaminants, such as arsenic (As). This integrative methodologic approach, based on the use of several techniques, allowed a complete characterization of these minerals. In addition to composition, the surface properties that are relevant for the adsorption ability, were also obtained. Therefore, the study revealed a diversity of behaviors for the identified phases, suggesting various roles in increasing the resilience of the contaminated systems