Papers by MATHEUS MELQUIADES NUNES
Nature Communications
Predictions of the magnitude and timing of leaf phenology in Amazonian forests remain highly cont... more Predictions of the magnitude and timing of leaf phenology in Amazonian forests remain highly controversial. Here, we use terrestrial LiDAR surveys every two weeks spanning wet and dry seasons in Central Amazonia to show that plant phenology varies strongly across vertical strata in old-growth forests, but is sensitive to disturbances arising from forest fragmentation. In combination with continuous microclimate measurements, we find that when maximum daily temperatures reached 35 °C in the latter part of the dry season, the upper canopy of large trees in undisturbed forests lost plant material. In contrast, the understory greened up with increased light availability driven by the upper canopy loss, alongside increases in solar radiation, even during periods of drier soil and atmospheric conditions. However, persistently high temperatures in forest edges exacerbated the upper canopy losses of large trees throughout the dry season, whereas the understory in these light-rich environmen...
Predictions of the magnitude and timing of leaf phenology in Amazonian forests remain highly cont... more Predictions of the magnitude and timing of leaf phenology in Amazonian forests remain highly controversial, which limits our understanding of future ecosystem function with a changing environment. Here, we use biweekly terrestrial LiDAR surveys spanning wet and dry seasons in Central Amazonia to show that plant phenology of old-growth forests varies strongly across strata but that this seasonality is sensitive to disturbances arising from forest fragmentation. In combination with continuous microclimate measurements, we found that when maximum daily temperatures reached 35 °C in the latter part of the dry season, the upper canopy of large trees in undisturbed forests shed their leaves and branches. By contrast, the understory greens-up with increased light availability driven by the upper canopy loss alongside more sunlight radiation, even during periods of drier soil and atmospheric conditions. However, persistently high temperatures on forest edges exacerbated the upper canopy los...
Nature Communications, 2021
The past 40 years in Southeast Asia have seen about 50% of lowland rainforests converted to oil p... more The past 40 years in Southeast Asia have seen about 50% of lowland rainforests converted to oil palm and other plantations, and much of the remaining forest heavily logged. Little is known about how fragmentation influences recovery and whether climate change will hamper restoration. Here, we use repeat airborne LiDAR surveys spanning the hot and dry 2015-16 El Niño Southern Oscillation event to measure canopy height growth across 3,300 ha of regenerating tropical forests spanning a logging intensity gradient in Malaysian Borneo. We show that the drought led to increased leaf shedding and branch fall. Short forest, regenerating after heavy logging, continued to grow despite higher evaporative demand, except when it was located close to oil palm plantations. Edge effects from the plantations extended over 300 metres into the forests. Forest growth on hilltops and slopes was particularly impacted by the combination of fragmentation and drought, but even riparian forests located within...
This work introduces species and respective relative parameters and importance values for each sp... more This work introduces species and respective relative parameters and importance values for each species found in an inventory carried out in Cerrado, Semi-deciduous and Ombrophilous forests in São Paulo State. Additionally, the work presents a stratification method based on the principal component analysis in order to stratify height and diameter classes. Similar groups were formed based on the number of individuals, species and basal area, stratifying diameter and height classes.
Dois procedimentos de preparo de amostra envolvendo digestão assistida por micro-ondas (MAD) e co... more Dois procedimentos de preparo de amostra envolvendo digestão assistida por micro-ondas (MAD) e combustão induzida por micro-ondas (MIC) em frascos fechados foram avaliados para posterior determinação de Cr e V por ICP-MS. Paralelamente foi avaliada a eficiência de dois arranjos instrumentais para a minimização de interferentes poliatômicos com célula dinâmica de reação (DRC) e interface de colisão-reação (CRI). As amostras de petróleo foram extraídas de três poços denominados A, B e C. O forno de micro-ondas Multiwave 3000 foi empregado para os procedimentos de MIC e MAD. Uma massa de 200 mg de amostra foi transferida para o frasco de quartzo e 6,0 mL de ácido nítrico conc. foi adicionado para ambos procedimentos. Entretanto, para o procedimento MIC as amostras foram envolvidas em filmes de polipropileno e colocadas em suporte de quartzo posicionado no frasco reacional. Para iniciar a ignição utilizou-se solução 6 mol/L de nitrato de amônio (50 µL). Os frascos foram fechados e press...
It is well known the analytical capability of inductively coupled plasma mass spectrometers (ICP-... more It is well known the analytical capability of inductively coupled plasma mass spectrometers (ICP-MSs) and its wide use in different fields of science. However some drawbacks, such as the occurrence of isobaric and polyatomic interferences and ionic suppression effects, are commonly related to this technique, mainly for ICP-MSs with quadrupole analyzers (ICP-QMS). Consequently, some elements as Cr and V are negatively affected due to polyatomic interferences caused by Ar, C, Cl, N, O and S species. Along the development of this method, different strategies were proposed such as dynamic reaction cell technologies (DRC) and collision reaction interface (CRI) in order to correct for these effects. The goal of the work here described was to evaluate the application of CRI and CCT devices for polyatomic interferences correction for Cr and V determination. Different media containing 1000 and 10000 mg L -1 of C, Cl, N, and S were employed in order to evaluate the polyatomic formation and co...
J. Anal. At. Spectrom., 2014
Laser ablation inductively coupled plasma mass spectrometry has been proven to be useful in life ... more Laser ablation inductively coupled plasma mass spectrometry has been proven to be useful in life sciences as can be observed by the increasing number of publications in this field.
Engenharia Agrícola, 2011
Este trabalho avaliou o efeito da diluição do dejeto de suíno com o efluente tratado a 50% (v/v),... more Este trabalho avaliou o efeito da diluição do dejeto de suíno com o efluente tratado a 50% (v/v), com vistas a aumentar a desnitrificação via fornecimento de carbono ao processo. Considerando-se a diluição estudada, a concentração média de N-NO3- na mistura foi de 47,9 + 14,5 mg L-1, e a DQO da mistura, na faixa de 17.543 + 675 mg L-1, resultando numa relação DQO/N-NO3- de 366, extremamente favorável à ocorrência da atividade desnitrificante no tanque de homogeneização da mistura. A concentração de N-NO3- foi reduzida biologicamente a 0,5 mg L-1 (cerca de 1% da concentração inicial). O procedimento testado promoveu, ainda, uma melhora na etapa de separação sólido-líquido, empregando coagulantes naturais, onde foi observado um consumo de tanino inferior ao esperado.
Science of The Total Environment, 2015
Selective herbicides in paddy rice fields, do not affect water quality. • Zooplankton communities... more Selective herbicides in paddy rice fields, do not affect water quality. • Zooplankton communities show good response with herbicide dissipation. • The use of commercial herbicide mixture has strong effects on freshwater Rotifers.
Revista Brasileira de Botânica, 2009
-(Tree community floristic and structure of alluvial forest fragments in São Sebastião da Bela Vi... more -(Tree community floristic and structure of alluvial forest fragments in São Sebastião da Bela Vista, Minas Gerais, Brazil). Fragments of alluvial forest in the South of Minas Gerais, Brazil, were studied in order to assess the vegetation structure, tree diversity and the most influential environmental variables on vegetation variations. The environment and vegetation data (dbh ≥ 5 cm) were collected in 54, 20 × 10 m, permanents plots allocated in a riverine forest and in five fragments of alluvial forests. In the plots, the survey totalled 2,064 tree individuals, distributed in 51 species. The canonical correspondence analysis detected a tree composition gradient in the first axis, related to Mg, organic matter and H + Al soil content, sand and clay percentage and soil water table level. The CCA second axis was associated with canopy coverage and soil silte percentage. Theses variables caused a plot group formation related to species distribution.
Revista Eletrônica em Gestão, Educação e Tecnologia Ambiental, 2013
Análise multitemporal da dinâmica da cobertura e uso da terra no município de caçapava do sul-rs ... more Análise multitemporal da dinâmica da cobertura e uso da terra no município de caçapava do sul-rs por meio de imagens landsat Multitemporal analysis of dynamics of cover and land use in the Caçapava do Sul city-RS through landsat images
Physiology & Behavior, 2014
The present study investigated the effects of quercetin in the impairment of memory and anxiogeni... more The present study investigated the effects of quercetin in the impairment of memory and anxiogenic-like behavior induced by cadmium (Cd) exposure. We also investigated possible alterations in acetylcholinesterase (AChE), Na(+),K(+)-ATPase and δ-aminolevulinate dehydratase (δ-ALA-D) activities as well as in oxidative stress parameters in the CNS. Rats were exposed to Cd (2.5mg/kg) and quercetin (5, 25 or 50mg/kg) by gavage for 45days. Animals were divided into eight groups (n=10-14): saline/control, saline/Querc 5mg/kg, saline/Querc 25mg/kg, saline/Querc 50mg/kg, Cd/ethanol, Cd/Querc 5mg/kg, Cd/Querc 25mg/kg and Cd/Querc 50mg/kg. Results demonstrated that Cd impaired memory has an anxiogenic effect. Quercetin prevented these harmful effects induced by Cd. AChE activity decreased in the cerebral cortex and hippocampus and increased in the hypothalamus of Cd-exposed rats. The Na(+),K(+)-ATPase activity decreased in the cerebral cortex, hippocampus and hypothalamus of Cd-exposed rats. Quercetin prevented these effects in AChE and Na(+),K(+)-ATPase activities. Reactive oxygen species production, thiobarbituric acid reactive substance levels, protein carbonyl content and double-stranded DNA fractions increased in the cerebral cortex, hippocampus and hypothalamus of Cd-exposed rats. Quercetin totally or partially prevents these effects caused by Cd. Total thiols (T-SHs), reduced glutathione (GSH), and reductase glutathione (GR) activities decreased and glutathione S-transferase (GST) activity increased in Cd exposed rats. Co-treatment with quercetin prevented reduction in T-SH, GSH, and GR activities and the rise of GST activity. The present findings show that quercetin prevents alterations in oxidative stress parameters as well as AChE and Na(+),K(+)-ATPase activities, consequently preventing memory impairment and anxiogenic-like behavior displayed by Cd exposure. These results may contribute to a better understanding of the neuroprotective role of quercetin, emphasizing the influence of this flavonoid in the diet for human health, possibly preventing brain injury associated with Cd intoxication.
Fuel Processing Technology, 2014
(AAM) is copyrighted and published by Elsevier. It is posted here by agreement between Elsevier a... more (AAM) is copyrighted and published by Elsevier. It is posted here by agreement between Elsevier and the University of Turin. Changes resulting from the publishing process-such as editing, corrections, structural formatting, and other quality control mechanisms-may not be reflected in this version of the text. The definitive version of the text was subsequently published in FUEL PROCESSING TECHNOLOGY, 126, 2014, 10.1016/j.fuproc.2014.05.031. You may download, copy and otherwise use the AAM for non-commercial purposes provided that your license is limited by the following restrictions: (1) You may use this AAM for non-commercial purposes only under the terms of the CC-BY-NC-ND license. (2) The integrity of the work and identification of the author, copyright owner, and publisher must be preserved in any copy.
CERNE, 2011
Neste estudo, objetivou-se conhecer os padrões de dinâmica da comunidade de árvores em fragmentos... more Neste estudo, objetivou-se conhecer os padrões de dinâmica da comunidade de árvores em fragmentos florestais aluviais nos períodos de 2005-2007 e 2007-2009. Para isso, foi estudado um fragmento de floresta ciliar e cinco fragmentos de floresta aluvial, no interior da planície de inundação do rio Sapucaí, em São Sebastião da Bela Vista, MG, inventariados, inicialmente, em 2005 e avaliados novamente em 2007 e em 2009. Os resultados demonstraram padrões diferenciados entre os fragmentos e os períodos de tempo. Nos fragmentos onde foi observada, em estudos anteriores, maior influência de enchentes e encharcamento do solo, a mortalidade de árvores foi maior no período de 2007-2009 do que no de 2005-2007. As taxas de mortalidade foram, de forma geral, maiores que as taxas de recrutamento, ocasionando a perda de indivíduos e a perda em área basal. Observando-se o histórico da área, é possível supor que essas perdas estão ocorrendo pela interação de dois fatores: i) excesso hídrico após uma...
Ultrasonics Sonochemistry, 2014
(AAM) is copyrighted and published by Elsevier. It is posted here by agreement between Elsevier a... more (AAM) is copyrighted and published by Elsevier. It is posted here by agreement between Elsevier and the University of Turin. Changes resulting from the publishing process-such as editing, corrections, structural formatting, and other quality control mechanisms-may not be reflected in this version of the text. The definitive version of the text was subsequently published in ULTRASONICS SONOCHEMISTRY, 21, 2014, 10.1016/j.ultsonch.2013.04.009. You may download, copy and otherwise use the AAM for non-commercial purposes provided that your license is limited by the following restrictions: (1) You may use this AAM for non-commercial purposes only under the terms of the CC-BY-NC-ND license. (2) The integrity of the work and identification of the author, copyright owner, and publisher must be preserved in any copy.
Ultrasonics Sonochemistry, 2009
A procedure using ultrasonic irradiation is proposed for sulfur removal of a petroleum product fe... more A procedure using ultrasonic irradiation is proposed for sulfur removal of a petroleum product feedstock. The procedure involves the combination of a peroxyacid and ultrasound-assisted treatment in order to comply with the required sulfur content recommended by the current regulations for fuels. The ultrasound-assisted oxidative desulfurization (UAOD) process was applied to a petroleum product feedstock using dibenzothiophene as a model sulfur compound. The influence of ultrasonic irradiation time, oxidizing reagents amount, kind of solvent for the extraction step and kind of organic acid were investigated. The use of ultrasonic irradiation allowed higher efficiency for sulfur removal in comparison to experiments performed without its application, under the same reactional conditions. Using the optimized conditions for UAOD, the sulfur removal was about 95% after 9 min of ultrasonic irradiation (20 kHz, 750 W, run at 40%), using hydrogen peroxide and acetic acid, followed by extraction with methanol.
Talanta, 2010
A microwave-induced combustion (MIC) procedure was applied for coal digestion for subsequent dete... more A microwave-induced combustion (MIC) procedure was applied for coal digestion for subsequent determination of As, Cd and Pb by inductively coupled plasma mass spectrometry (ICP-MS) and Hg using cold vapor (CV) generation coupled to ICP-MS. Pellets of coal (500 mg) were combusted using 20 bar of oxygen and ammonium nitrate as aid for ignition. The use of nitric acid as absorbing solution (1.7, 3.5, 5.0, 7.0 and 14 mol L −1) was evaluated. For coal samples with higher ash content, better results were found using 7.0 mol L −1 HNO 3 and an additional reflux step of 5 min after combustion step. For coal samples with ash content lower than 8%, 5.0 mol L −1 nitric acid was suitable to the absorption of all analytes. Accuracy was evaluated using certified reference material (CRM) of coal and spikes. Agreement with certified values and recoveries was better than 95 and 97%, respectively, for all the analytes. For comparison of results, a procedure recommended by the American Society of Testing and Materials (ASTM) was used. Additionally, a conventional microwave-assisted digestion (MAD) in pressurized vessels was also performed. Using ASTM procedure, analyte losses were observed and a relatively long time was necessary for digestion (>6 h). By comparison with MAD procedure, higher sample mass can be digested using MIC allowing better limits of detection. Additionally, the use of concentrated acids was not necessary that is an important aspect in order to obtain low blank levels and lower limits of detection, respectively. The residual carbon content in digests obtained by MAD and MIC was about 15% and <1%, respectively, showing the better digestion efficiency of MIC procedure. Using MIC it was possible to digest completely and simultaneously up to eight samples in only 25 min with relatively lower generation of laboratory effluents.
Revista Árvore, 2011
Com o objetivo de avaliar o impacto de uma enchente de grandes proporções sobre os indivíduos arb... more Com o objetivo de avaliar o impacto de uma enchente de grandes proporções sobre os indivíduos arbóreos, foi realizada, no ano de 2007, a avaliação de uma área aluvial localizada em São Sebastião da Bela Vista, MG, onde foram amostrados cinco fragmentos aluviais e uma floresta ciliar, inventariados inicialmente em 2005. Os resultados indicaram que, após a enchente, a dinâmica no curto-prazo foi caracterizada por taxa de mortalidade superior à de recrutamento e taxa de perda maior do que a de ganho em área basal. Entretanto, a estrutura da comunidade não foi alterada, pois a frequência de indivíduos sobreviventes e de mortos nas classes diamétricas foi proporcional ao número inicial de indivíduos em cada classe. Os resultados permitiram concluir que, apesar de não terem sido observadas alterações na estrutura diamétrica, a dinâmica da comunidade arbórea refletiu o distúrbio causado pela enchente.
Parasitology, 2011
SUMMARYThe aim of this study was to evaluate the activity of delta-aminolevulinate dehydratase (δ... more SUMMARYThe aim of this study was to evaluate the activity of delta-aminolevulinate dehydratase (δ-ALA-D) in red blood cells of rats infected with Trypanosoma evansi and establish its association with haematocrit, serum levels of iron and zinc and lipid peroxidation. Thirty-six male rats (Wistar) were divided into 2 groups with 18 animals each. Group A was non-infected while Group B was intraperitoneally infected, receiving 7·5×106 trypomastigotes per animal. Each group was divided into 3 subgroups of 6 rats and blood was collected during different periods post-infection (p.i.) as follows: day 5 (A1 and B1), day 15 (A2 and B2) and day 30 PI (A3 and B3). Blood samples were collected by cardiac puncture to estimate red blood cell parameters (RBC), δ-ALA-D activity and serum levels of iron, zinc and thiobarbituric acid reactive substances (TBARS). Rats in group B showed a significant (P<0·05) reduction of RBC count, haemoglobin concentration and haematocrit at days 5 and 15 p.i. The ...
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Papers by MATHEUS MELQUIADES NUNES