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1.
Sci Total Environ ; 930: 172666, 2024 Jun 20.
Artigo em Inglês | MEDLINE | ID: mdl-38653415

RESUMO

The net effect of forest disturbances, such as fires and harvesting, on soil greenhouse gas fluxes is determined by their impacts on both biological and physical factors, as well as the temporal dynamics of these effects post-disturbance. Although harvesting and fire may have distinct effects on soil carbon (C) dynamics, the temporal patterns in soil CO2 and CH4 fluxes and the potential differences between types of disturbances, remain poorly characterized in boreal forests. In this study, we measured soil CO2 and CH4 fluxes using a off-axis integrated cavity output spectroscopy system in snow-free seasons over two years in post-harvest and post-fire chronosequence sites within a mixedwood boreal forest in northwestern Ontario, Canada. Soil CO2 efflux showed a post-disturbance peak, with differing dynamics depending on the disturbance type: post-harvest stands exhibited a nearly tenfold increase (from ∼1 to ∼11 µmol CO2.m-2.s-1) from 1 to 9-10 years post-disturbance, followed by a steep decline; post-fire stands showed a more gradual increase, peaking at ∼6-7.2 µmol CO2.m-2.s-1 after ∼12-15 years. The youngest post-harvest stands were net sources of CH4,whereas post-fire stands were never net CH4 sources. In both disturbance types, the strength of the CH4 sink increased with stand age, approaching ∼2.4 nmol.m-2.s-1 by 15 years post-disturbance. Volumetric water content, bulk density, litter depth, and pH were significant predictors of CO2 fluxes; for CH4 fluxes, litter depth, pH, and the interaction of VWC and soil temperature were significant predictors in both disturbance types, with EC also showing a relationship in post-harvest stands. Our findings indicate that while soil CH4 oxidation rapidly recovers following disturbance, both post-harvest and post-fire stands show a multi-decade release of soil CO2 that is too large to be offset by C gains over this period.

2.
Sci Total Environ ; 922: 171302, 2024 Apr 20.
Artigo em Inglês | MEDLINE | ID: mdl-38428607

RESUMO

Green roofs have been increasingly used to improve stormwater management, but poor vegetation performance on roof systems, varying with vegetation type, can degrade discharge quality. Biochar has been suggested as an effective substrate additive for green roofs to improve plant performance and discharge quality. However, research on the effects of biochar and vegetation on discharge quality in the long term is lacking and the underlying mechanisms involved are unclear. We examined the effects of biochar amendment and vegetation on discharge quality on organic-substrate green roofs with pre-grown sedum mats and direct-seeded native plants for three years and investigated the key factors influencing discharge quality. Sedum mats reduced the leaching of nutrients and particulate matter by 6-64% relative to native plants, largely due to the higher initial vegetation cover of the former. Biochar addition to sedum mat green roofs resulted in the best integrated water quality due to enhanced plant cover and sorption effects. Structural equation modeling revealed that nutrient leaching was primarily influenced by rainfall depth, time, vegetation cover, and substrate pH. Although biochar-amended sedum mats showed better discharge quality from organic-substrate green roofs, additional ecosystem services may be provided by native plants, suggesting future research to optimize plant composition and cover and biochar properties for sustainable green roofs.


Assuntos
Carvão Vegetal , Sedum , Qualidade da Água , Ecossistema , Conservação dos Recursos Naturais/métodos , Chuva , Plantas
3.
J Environ Manage ; 350: 119068, 2024 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-37821334

RESUMO

Deforestation in the Amazon has resulted in large areas of depleted soils on abandoned pastures and agricultural sites that present a restoration challenge central to protecting biodiversity and ecosystem function in the region. Biochar - charcoal made from waste materials - can improve soil physical, chemical, and biological properties, but the few tropical field trials to date do not give consistent results regarding tree growth. This study presents three years of soil performance and tree growth of a secondary forest shading nontimber forest product (NTFP) plantations of Ocotea quixos (Lauraceae), Myroxylon balsamum (Fabaceae), and their mixture. Open kiln and traditional mound biochars were added at 10 t ha-1 at two sites with contrasting soil types. Biochar additions resulted in pronounced effects on soil properties that varied over time and with depth in the soil profile. Biochar additions generally increased soil organic matter, electrical conductivity, and plant nutrients (in particular K, Ca, and N), but there were interactive effects of NTFP treatments, and stronger responses on the poorer soil type. Biochar amendments resulted in increased tree growth, with a 29 ± 12% increase in aboveground biomass (AGB) on plots amended with kiln biochar and a 23 ± 9% increase in plots with mound biochar compared to controls. Tree species also varied in growth responses to biochar additions, with the largest increases observed in Jaccaranda copaia and Piptocoma discolor. Significant interactions between biochar and NTFP treatments were also seen for tree growth responses, such as Cecropia spp., which only showed increased biomass on mound biochar plots planted with Ocotea quixos. Overall, our results demonstrate a stronger effect of biochar in less favorable soil conditions, and an overriding effect of the legume NTFP in richer soils, and suggest that additions of biochar and legumes are important options to increase productivity and ecological resilience in tropical forest restoration.


Assuntos
Fabaceae , Solo , Solo/química , Ecossistema , Carvão Vegetal/química , Equador , Florestas , Árvores , Verduras
4.
Nutrients ; 15(21)2023 Nov 05.
Artigo em Inglês | MEDLINE | ID: mdl-37960343

RESUMO

Type 2 diabetes mellitus (T2DM) remains a global health concern. Emerging clinical trial (CT) evidence suggests that probiotic intervention may promote a healthy gut microbiome in individuals with T2DM, thereby improving management of the disease. This systematic literature review summarizes thirty-three CTs investigating the use of oral probiotics for the management of T2DM. Here, twenty-one studies (64%) demonstrated an improvement in at least one glycemic parameter, while fifteen studies (45%) showed an improvement in at least one lipid parameter. However, no article in this review was able to establish a uniform decrease in glycemic, lipid, or blood pressure profiles. The lack of consistency across the studies may be attributed to differences in probiotic composition, duration of probiotic consumption, and probiotic dose. An interesting finding of this literature review was the beneficial trend of metformin and probiotic co-administration. Here, patients with T2DM taking metformin demonstrated enhanced glycemic control via the co-administration of probiotics. Taken together, the overall positive findings reported across the studies in combination with minimal adverse effects constitute ground for further quality CTs. This review provides recommendations for future CTs that may address the shortcomings of the current studies and help to extract useful data from future investigations of the use of probiotics in T2DM management.


Assuntos
Diabetes Mellitus Tipo 2 , Metformina , Probióticos , Humanos , Diabetes Mellitus Tipo 2/tratamento farmacológico , Glicemia , Probióticos/uso terapêutico , Lipídeos
5.
Environ Sci Technol ; 57(41): 15475-15486, 2023 10 17.
Artigo em Inglês | MEDLINE | ID: mdl-37788297

RESUMO

Urbanization has degraded ecosystem services on a global scale, and cities are vulnerable to long-term stresses and risks exacerbated by climate change. Green infrastructure (GI) has been increasingly implemented in cities to improve ecosystem functions and enhance city resilience, yet GI degradation or failure is common. Biochar has been recently suggested as an ideal substrate additive for a range of GI types due to its favorable properties; however, the generality of biochar benefits the GI ecosystem function, and the underlying mechanisms remain unclear. Here, we present a global meta-analysis and synthesis and demonstrate that biochar additions pervasively benefit a wide range of ecosystem functions on GI. Biochar applications were found to improve substrate water retention capacity by 23% and enhance substrate nutrients by 12-31%, contributing to a 33% increase in plant total biomass. Improved substrate physicochemical properties and plant growth together reduce discharge water volume and improve discharge water quality from GI. In addition, biochar increases microbial biomass on GI by ∼150% due to the presence of biochar pores and enhanced microbial growth conditions, while also reducing CO2 and N2O emissions. Overall results suggest that biochar has great potential to enhance GI ecosystem functions as well as urban sustainability and resilience.


Assuntos
Ecossistema , Crescimento Sustentável , Cidades , Carvão Vegetal/química , Solo/química
6.
Sci Total Environ ; 901: 165861, 2023 Nov 25.
Artigo em Inglês | MEDLINE | ID: mdl-37516177

RESUMO

Unique properties of biochar render it appealing for revegetating and decontaminating historic, barren, and chemically complex mine tailings. Bottom ash from bioenergy facilities can contain high levels of charcoal residue, and thus qualify as a type of biochar; the wide availability of this material at low cost makes it of particular interest in the context of tailings remediation. Nevertheless, bottom ash is variable and often contains residual toxic metal/loids that could be phytoabsorbed into plant tissues. We implemented a replicated field trial on historic contaminated metal mine tailings in Northern Ontario (Canada) over a range of high­carbon wood ash biochar (HCWAB) dosages (0-30 t/ha) to evaluate tree and substrate responses. Sapling survivorship and aboveground biomass growth were quantified over a 4-year period; substrate chemical parameters were measured using acid-digestion and ICP-MS, as well as ion exchange resin probes. To assess elemental composition of sapling tissues, we used electron probe microanalysis combined with laser-ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) on intact samples across the range of dosages applied. Survival and growth of saplings peaked at mid-range ash dosages of 3-6 t/ha. Similarly, substrate ion availability of P, K, and Zn were stable at lower dosages, but increased above 6 t/ha. The trace amounts of toxic metal/loids of concern measured in wood ash (As, Cd, Cu, and Pb) did not result in significantly increased sapling tissue concentrations at low to moderate dosages, but in some cases tissue contaminant levels were elevated at the highest dosage examined (30 t/ha). Our findings highlight the potential for high­carbon wood ash biochar to be used for metal mine restoration at low to moderate dosages.

7.
PLoS One ; 18(7): e0288291, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37463169

RESUMO

Declining tree health status due to pollutant impacts and nutrient imbalance is widespread in urban forests; however, chemical fertilizer use is increasingly avoided to reduce eutrophication impacts. Biochar (pyrolyzed organic waste) has been advocated as an alternative soil amendment, but biochar alone generally reduces plant N availability. The combination of biochar and either organic forms of N or Plant Growth Promoting Microbes (PGPMs) as biofertilizers may address these challenges. We examined the effects of two wood biochar types with Bacillus velezensis and an inactivated yeast (IY) biofertilizer in a three-month factorial greenhouse experiment with Acer saccharinum L. (silver maple) saplings grown in a representative urban soil. All treatments combining biochars with biofertilizers significantly increased sapling growth, with up to a 91% increase in biomass relative to controls. Growth and physiological responses were closely related to nutrient uptake patterns, with nutrient vector analyses indicating that combined biochar and biofertilizer treatments effectively addressed nutrient limitations of both macronutrients (N, P, K, Mg, Ca), and micronutrients (B, Fe, Mn, Mo, Na, S, and Zn). Biochar-biofertilizer treatments also reduced foliar concentrations of Cu, suggesting potential to mitigate toxic metal impacts common in urban forestry. We conclude that selected combinations of biochar and biofertilizers have substantial promise to address common soil limitations to tree performance in urban settings.


Assuntos
Acer , Poluentes do Solo , Carvão Vegetal , Nutrientes , Solo , Árvores
8.
Front Oncol ; 13: 1171278, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37213298

RESUMO

Background: Irreversible electroporation (IRE) has been previously investigated in preclinical trials as a treatment for intracranial malignancies. Here, we investigate next generation high-frequency irreversible electroporation (H-FIRE), as both a monotherapy and a combinatorial therapy, for the treatment of malignant gliomas. Methods: Hydrogel tissue scaffolds and numerical modeling were used to inform in-vivo H-FIRE pulsing parameters for our orthotopic tumor-bearing glioma model. Fischer rats were separated into five treatment cohorts including high-dose H-FIRE (1750V/cm), low-dose H-FIRE (600V/cm), combinatorial high-dose H-FIRE + liposomal doxorubicin, low-dose H-FIRE + liposomal doxorubicin, and standalone liposomal doxorubicin groups. Cohorts were compared against a standalone tumor-bearing sham group which received no therapeutic intervention. To further enhance the translational value of our work, we characterize the local and systemic immune responses to intracranial H-FIRE at the study timepoint. Results: The median survival for each cohort are as follows: 31 days (high-dose H-FIRE), 38 days (low-dose H-FIRE), 37.5 days (high-dose H-FIRE + liposomal doxorubicin), 27 days (low-dose H-FIRE + liposomal doxorubicin), 20 days (liposomal doxorubicin), and 26 days (sham). A statistically greater overall survival fraction was noted in the high-dose H-FIRE + liposomal doxorubicin (50%, p = 0.044), high-dose H-FIRE (28.6%, p = 0.034), and the low-dose H-FIRE (20%, p = 0.0214) compared to the sham control (0%). Compared to sham controls, brain sections of rats treated with H-FIRE demonstrated significant increases in IHC scores for CD3+ T-cells (p = 0.0014), CD79a+ B-cells (p = 0.01), IBA-1+ dendritic cells/microglia (p = 0.04), CD8+ cytotoxic T-cells (p = 0.0004), and CD86+ M1 macrophages (p = 0.01). Conclusions: H-FIRE may be used as both a monotherapy and a combinatorial therapy to improve survival in the treatment of malignant gliomas while also promoting the presence of infiltrative immune cells.

9.
Ecol Appl ; 33(4): e2832, 2023 06.
Artigo em Inglês | MEDLINE | ID: mdl-36864680

RESUMO

Many invasive and some native tree species in North America exhibit strong allelopathic effects that may contribute to their local dominance. Pyrogenic carbon (PyC; including soot, charcoal, and black carbon) is produced by the incomplete combustion of organic matter and is widespread in forest soils. Many forms of PyC have sorptive properties that can reduce the bioavailability of allelochemicals. We investigated the potential for PyC produced by controlled pyrolysis of biomass ("biochar" [BC]) to reduce the allelopathic effects of black walnut (Juglans nigra) and Norway maple (Acer platanoides), a common native tree species and a widespread invasive species in North America, respectively. Seedling growth of two native tree species (Acer saccharinum [silver maple] and Betula papyrifera [paper birch]) in response to leaf-litter-incubated soils was examined; litter incubation treatments included leaves of black walnut, Norway maple, and a nonallelopathic species (Tilia americana [American basswood]) in a factorial design with varying dosages; responses to the known primary allelochemical of black walnut (juglone) were also examined. Juglone and leaf litter of both allelopathic species strongly suppressed seedling growth. BC treatments substantially mitigated these effects, consistent with the sorption of allelochemicals; in contrast no positive effects of BC were observed in leaf litter treatments involving controls or additions of nonallelopathic leaf litter. Treatments of leaf litter and juglone with BC increased the total biomass of silver maple by ~35% and in some cases more than doubled the biomass of paper birch. We conclude that BCs have the capacity to largely counteract allelopathic effects in temperate forest systems, suggesting the effects of natural PyC in determining forest community structure, and also the applied use of BC as a soil amendment to mitigate allelopathic effects of invasive tree species.


Assuntos
Carvão Vegetal , Árvores , Carvão Vegetal/análise , Prata/análise , Solo , Plântula , Folhas de Planta/fisiologia
10.
Biochar ; 4(1): 61, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36317055

RESUMO

Green roofs are exposed to high winds and harsh environmental conditions that can degrade vegetation and erode substrate material, with negative consequences to ecosystem services. Biochar has been promoted as an effective substrate additive to enhance plant performance, but unprocessed biochars are susceptible to wind and water erosion. Applications of granulated biochars or chemical dust suppressants are suggested as a means to mitigate biochar and substrate erosion; however, research on biochar type and chemical dust suppressant use on biochar and substrate erosion is lacking. Vegetation is a crucial factor that influences substrate erosion, yet plant responses may vary with biochar type and chemical dust suppressant; thus, the effects of possible mitigation measures on biochar and substrate erosion are unclear. We investigated the effects of surface-applied granulated and unprocessed biochars and an organic dust suppressant (Entac™) on biochar and substrate erosion on green roofs with Sedum album L. and a native plant mix. Our results show that 94% of unprocessed biochars were lost from green roofs after 2 years regardless of the Entac™ amendment, likely due to the lightweight nature and fragmentation of biochar particles. In contrast, granulation of biochars reduced the biochar erosion and total substrate erosion by 74% and 39%, respectively, possibly due to enhanced biochar bulk density and particle size and improved moisture retention of biochar-amended substrates. Additionally, Sedum album better reduced biochar and substrate erosion than the native plant mix, likely due to rapid development of high vegetation cover that reduced wind exposure and enhanced substrate moisture retention. We conclude that applications of granulated biochars can substantially reduce biochar and substrate erosion on green roofs, improving green roof sustainability. Supplementary Information: The online version contains supplementary material available at 10.1007/s42773-022-00186-7.

11.
J Environ Manage ; 318: 115506, 2022 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-35753127

RESUMO

Biochar, due to its favourable physiochemical properties, has been promoted as an ideal substrate additive on green roofs, with potential benefits to hydrological function. However, biochar is susceptible to water erosion, which may result in biochar loss and water pollution. The use of granulated biochars or biochars in large particle sizes could potentially alleviate biochar erosion loss, but effects on leachate quality have not been investigated. Also, biochar type and particle size influence plant performance, and effects on discharge quality may vary with vegetation. We assessed the effects of unprocessed and granulated biochars at five (0.25-0.5 mm, 0.5-1 mm, 1-2 mm, 2-2.8 mm, 2.8-4 mm) and four (1-2 mm, 2-2.8 mm, 2.8-4 mm, and 4-6.3 mm) particle size ranges, respectively, on leachate quality on a typical green roof substrate, with presence and absence of vegetation (Agastache foeniculum - a drought-tolerant native forb). We evaluated integrated leachate quality using the CCME Water Quality Index (WQI). Unprocessed biochars reduced nutrient leaching due to increased water retention capacity (WRC) and total porosity. In contrast, granulated biochars, although showing less pronounced mitigation of nutrient leaching, reduced total suspended solids (TSS) and improved WQI in leachate due to enhanced plant performance. In addition, small biochar particles better reduced nutrient leaching and particle loss than large biochar particles, possibly due to increased WRC and formation of water-stable aggregates. The presence of vegetation generally reduced the leaching of nutrients and TSS, consistent with plant nutrient uptake and root substrate stabilization. However, plant biomass was correlated with increased total N leaching, likely due to litter inputs and rapid litter decomposition. We conclude that applications of granulated biochars may best improve discharge quality from green roofs through sorption effects and by enhancing plant performance.


Assuntos
Carvão Vegetal , Qualidade da Água , Biomassa , Carvão Vegetal/química , Tamanho da Partícula , Solo/química
12.
Sci Total Environ ; 813: 152638, 2022 Mar 20.
Artigo em Inglês | MEDLINE | ID: mdl-34968588

RESUMO

Green roofs have been widely promoted as a means to enhance ecosystem services in cities, but roofs present a harsh growing environment for plants. Biochar is suggested to be a highly beneficial substrate additive for green roof systems due to its low weight, high nutrient and water retention capacity, and recalcitrance. However, biochar is susceptible to wind and water erosion, which may result in biochar loss and negative environmental impacts. Applications of biochar as large particles or in granulated form may mitigate biochar erosion potential, but relevant data on plant performance and substrate properties are lacking. We examined the effects of granulated and conventional biochars at a range of particle sizes on plant performance of the drought-tolerant forb Agastache foeniculum. We found that granulated biochar strongly enhanced plant growth, reproduction, and physiological status, acting to neutralize pH and enhance water retention capacity of the substrate. In contrast, although conventional biochar reduced substrate bulk density and enhanced substrate total porosity and water retention capacity, it suppressed plant growth. Our results also suggest that granulated biochar at intermediate particle sizes (2-2.8 mm) best enhanced plant performance. We conclude that use of granulated biochars on green roofs can strongly promote plant performance while increasing water infiltration and retention.


Assuntos
Conservação dos Recursos Naturais , Ecossistema , Carvão Vegetal , Plantas
13.
Biochar ; 3(4): 437-455, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34723131

RESUMO

A number of processes for post-production treatment of "raw" biochars, including leaching, aeration, grinding or sieving to reduce particle size, and chemical or steam activation, have been suggested as means to enhance biochar effectiveness in agriculture, forestry, and environmental restoration. Here, I review studies on post-production processing methods and their effects on biochar physio-chemical properties and present a meta-analysis of plant growth and yield responses to post-processed vs. "raw" biochars. Data from 23 studies provide a total of 112 comparisons of responses to processed vs. unprocessed biochars, and 103 comparisons allowing assessment of effects relative to biochar particle size; additional 8 published studies involving 32 comparisons provide data on effects of biochar leachates. Overall, post-processed biochars resulted in significantly increased average plant growth responses 14% above those observed with unprocessed biochar. This overall effect was driven by plant growth responses to reduced biochar particle size, and heating/aeration treatments. The assessment of biochar effects by particle size indicates a peak at a particle size of 0.5-1.0 mm. Biochar leachate treatments showed very high heterogeneity among studies and no average growth benefit. I conclude that physiochemical post-processing of biochar offers substantial additional agronomic benefits compared to the use of unprocessed biochar. Further research on post-production treatments effects will be important for biochar utilization to maximize benefits to carbon sequestration and system productivity in agriculture, forestry, and environmental restoration. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s42773-021-00115-0.

14.
Nat Commun ; 12(1): 889, 2021 02 09.
Artigo em Inglês | MEDLINE | ID: mdl-33563999

RESUMO

A key uncertainty in quantifying dead wood carbon (C) stocks-which comprise ~8% of total forest C pools globally-is a lack of accurate dead wood C fractions (CFs) that are employed to convert dead woody biomass into C. Most C estimation protocols utilize a default dead wood CF of 50%, but live tree studies suggest this value is an over-estimate. Here, we compile and analyze a global database of dead wood CFs in trees, showing that dead wood CFs average 48.5% across forests, deviating significantly from 50%, and varying systematically among biomes, taxonomic divisions, tissue types, and decay classes. Utilizing data-driven dead wood CFs in tropical forests alone may correct systematic overestimates in dead wood C stocks of ~3.0 Pg C: an estimate approaching nearly the entire dead wood C pool in the temperate forest biome. We provide for the first time, robust empirical dead wood CFs to inform global forest C estimation.


Assuntos
Carbono/análise , Madeira/química , Biodegradação Ambiental , Carbono/metabolismo , Ciclo do Carbono , Clima , Florestas , Estruturas Vegetais/química , Estruturas Vegetais/classificação , Árvores/química , Árvores/classificação , Madeira/metabolismo
15.
Nature ; 579(7797): 80-87, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-32132693

RESUMO

Structurally intact tropical forests sequestered about half of the global terrestrial carbon uptake over the 1990s and early 2000s, removing about 15 per cent of anthropogenic carbon dioxide emissions1-3. Climate-driven vegetation models typically predict that this tropical forest 'carbon sink' will continue for decades4,5. Here we assess trends in the carbon sink using 244 structurally intact African tropical forests spanning 11 countries, compare them with 321 published plots from Amazonia and investigate the underlying drivers of the trends. The carbon sink in live aboveground biomass in intact African tropical forests has been stable for the three decades to 2015, at 0.66 tonnes of carbon per hectare per year (95 per cent confidence interval 0.53-0.79), in contrast to the long-term decline in Amazonian forests6. Therefore the carbon sink responses of Earth's two largest expanses of tropical forest have diverged. The difference is largely driven by carbon losses from tree mortality, with no detectable multi-decadal trend in Africa and a long-term increase in Amazonia. Both continents show increasing tree growth, consistent with the expected net effect of rising atmospheric carbon dioxide and air temperature7-9. Despite the past stability of the African carbon sink, our most intensively monitored plots suggest a post-2010 increase in carbon losses, delayed compared to Amazonia, indicating asynchronous carbon sink saturation on the two continents. A statistical model including carbon dioxide, temperature, drought and forest dynamics accounts for the observed trends and indicates a long-term future decline in the African sink, whereas the Amazonian sink continues to weaken rapidly. Overall, the uptake of carbon into Earth's intact tropical forests peaked in the 1990s. Given that the global terrestrial carbon sink is increasing in size, independent observations indicating greater recent carbon uptake into the Northern Hemisphere landmass10 reinforce our conclusion that the intact tropical forest carbon sink has already peaked. This saturation and ongoing decline of the tropical forest carbon sink has consequences for policies intended to stabilize Earth's climate.


Assuntos
Dióxido de Carbono/metabolismo , Sequestro de Carbono , Florestas , Árvores/metabolismo , Clima Tropical , África , Atmosfera/química , Biomassa , Brasil , Secas , História do Século XX , História do Século XXI , Modelos Teóricos , Temperatura
16.
Cancers (Basel) ; 11(12)2019 Nov 23.
Artigo em Inglês | MEDLINE | ID: mdl-31771214

RESUMO

Treatment of intracranial disorders suffers from the inability to accumulate therapeutic drug concentrations due to protection from the blood-brain barrier (BBB). Electroporation-based therapies have demonstrated the capability of permeating the BBB, but knowledge of the longevity of BBB disruption (BBBD) is limited. In this study, we quantify the temporal, high-frequency electroporation (HFE)-mediated BBBD in an in vivo healthy rat brain model. 40 male Fisher rats underwent HFE treatment; two blunt tipped monopolar electrodes were advanced into the brain and 200 bursts of HFE were delivered at a voltage-to-distance ratio of 600 V/cm. BBBD was verified with contrast enhanced T1W MRI (gadopentetate dimeglumine) and pathologically (Evans blue dye) at time points of 1, 24, 48, 72, and 96 h after HFE. Contrast enhanced T1W scans demonstrated BBBD for 1 to 72 h after HFE but intact BBB at 96 h. Histologically, tissue damage was restricted to electrode insertion tracks. BBBD was induced with minimal muscle contractions and minimal cell death attributed to HFE. Numerical modeling indicated that brief BBBD was induced with low magnitude electric fields, and BBBD duration increased with field strength. These data suggest the spatiotemporal characteristics of HFE-mediated BBBD may be modulated with the locally applied electric field.

17.
Front Microbiol ; 10: 1929, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31507554

RESUMO

Glycerol is an important by-product of the biodiesel industry and its transformation into value-added products like keto acids is being actively pursued in order to improve the efficacy of this renewable energy sector. Here, we report that the enhanced production of α-ketoglutarate (KG) effected by Pseudomonas fluorescens in a mineral medium supplemented with manganese (Mn) is propelled by the increased activities of succinate semialdehyde dehydrogenase (SSADH), γ-aminobutyric acid aminotransaminase (GABAT), and isocitrate lyase (ICL). The latter generates glyoxylate and succinate two key metabolites involved in this process. Fumarate reductase (FRD) also aids in augmenting the pool of succinate, a precursor of succinate semialdehyde (SSA). The latter is then carboxylated to KG with the assistance of α-ketoglutarate decarboxylase (KDC). These enzymes work in tandem to ensure copious secretion of the keto acid. When incubated with glycerol in the presence of bicarbonate ( H C O 3 - ), cell-free extracts readily produce KG with a metabolite fingerprint attributed to glutamate, γ-aminobutyric acid (GABA), succinate and succinate semialdehyde. Further targeted metabolomic and functional proteomic studies with high-performance liquid chromatography (HPLC), nuclear magnetic resonance (NMR) and gel electrophoresis techniques provided molecular insights into this KG-generating machinery. Real-time quantitative polymerase chain reaction (RT-qPCR) analyses revealed the transcripts responsible for ICL and SSADH were elevated in the Mn-supplemented cultures. This hitherto unreported metabolic network where ICL and SSADH orchestrate the enhanced production of KG from glycerol, provides an elegant means of converting an industrial waste into a keto acid with wide-ranging application in the medical, cosmetic, and chemical sectors.

18.
Sci Total Environ ; 664: 363-373, 2019 May 10.
Artigo em Inglês | MEDLINE | ID: mdl-30743128

RESUMO

Bamboo-derived biocarbon (BA900) and wood-derived biocarbon (THOC700) have exhibited graphite-like characteristics through transmission electron microscopy, X-ray diffraction (XRD), and Attenuated Total Reflectance (ATR) spectroscopy analysis. Lightweight composites of biocarbons were manufactured by a mechanism of shear controlled melt-phase mixing, ensuring the preservation of biocarbon pore structures and simultaneously taking full advantage of low density polyolefin substrates. Effective tensile strength was improved by approximately 10% in the polypropylene-based bamboo carbon composite, whereas no appreciable improvement was observed in the tensile and impact strength of bamboo-derived biocarbon formulations compared to neat polymer. However, the tensile and flexural moduli and flexural strength of the THOC700-PP composites were significantly enhanced, by 56%, 67%, and 19%, respectively, compared to neat polymer. The most significant finding of the investigation was the retention of density in polyolefin polymer (ρPP = 0.91; ρTHOC = 0.95; ρBA900 = 0.99), with enhanced mechanical performance useful for lightweighting applications. Bamboo biocarbon provides a viable alternative to another abundantly available industrial carbon feedstock, reclaimed carbon fiber (RCF), in manufacturing thermoplastic composites. The origin of the carbon plays an important role in defining ultimate composite performance. A mechanism for retaining lightweight structural performance has been proposed in this original work, paving the way to develop next-generation lightweight thermoplastic structures for transportation and other industrial and consumer products.


Assuntos
Fibra de Carbono , Materiais de Construção , Carbono , Grafite , Teste de Materiais , Microscopia Eletrônica de Varredura , Microscopia Eletrônica de Transmissão , Polímeros , Polipropilenos , Porosidade , Resistência à Tração , Madeira , Difração de Raios X
19.
Sci Total Environ ; 658: 1344-1354, 2019 Mar 25.
Artigo em Inglês | MEDLINE | ID: mdl-30677995

RESUMO

Charcoal is a ubiquitous legacy of wildfire in terrestrial systems that often contributes to rapid revegetation following disturbance; the use of charcoal soil amendments, or "biochars", to promote plant growth has received recent research attention and increasing applied use. Despite its widespread use, well-resolved quantitative estimates of dose-response relationships for biochar effects on plant growth are nonexistent, and studies of biochar dosage effects on plant ecophysiology are minimal. We investigated the effects of biochar dosage on plant growth and ecophysiology in a glasshouse experiment involving two common early-successional plants, Abutilon theophrasti and Trifolium repens. Plants were grown in disturbed temperate soils with increasing dosages of wood biochars: 0, 2, 4, 6, 8, 10, 20, 30, 40, 50 t/ha. We measured leaf-level gas-exchange traits (Amax, gs, WUE), chlorophyll concentration, and leaf area growth throughout the experiment. At the end of the experiment, we measured biomass, foliar nutrition, and soil properties (pH, EC, C and N). Responses of biomass and physiological traits were highly dose-dependent, followed primarily unimodal forms, and differed in some traits between species. Increases in the uptake of K, P, and Mg, were responsible for accelerated growth. Biochars also generally increased the concentration of micronutrients, especially B. As a result, nutrient stoichiometry shifted substantially: in A. theophrasti, biochars increased C:N, P:N, and K:N ratios, suggesting nitrogen dilution or induced deficiency at higher dosages. This work supports the general hypothesis that ecophysiological responses to biochar are dose-dependent and driven mainly by changes in nutrient availability. Additional work is necessary to understand the broader ecological impacts of heterogeneity in soil pyrogenic C levels to succession and ecosystem function.


Assuntos
Carvão Vegetal/metabolismo , Malvaceae/fisiologia , Nutrientes/metabolismo , Trifolium/fisiologia , Relação Dose-Resposta a Droga , Malvaceae/crescimento & desenvolvimento , Trifolium/crescimento & desenvolvimento
20.
Can J Cardiol ; 34(12): 1688.e21-1688.e23, 2018 12.
Artigo em Inglês | MEDLINE | ID: mdl-30527167

RESUMO

Diaphragmatic eventration in old age is a rare phenomenon. Typically, it is thought to originate as a result of failure of development of the muscles of the diaphragm. Less commonly, it can occur secondary to acquired conditions resulting from spinal cord or phrenic nerve injury and is only detected incidentally when the patient presents with dyspnea, chest infection, or cardiac compression symptoms. Herein, we report a case of right diaphragmatic paralysis in a 58-year-old man with a presentation of marked elevation of the right hemidiaphragm and ascites causing a picture compatible with cardiac tamponade.


Assuntos
Tamponamento Cardíaco/etiologia , Eventração Diafragmática/complicações , Paralisia Respiratória/complicações , Ascite/diagnóstico por imagem , Tamponamento Cardíaco/diagnóstico por imagem , Eventração Diafragmática/diagnóstico por imagem , Ecocardiografia Transesofagiana , Humanos , Masculino , Pessoa de Meia-Idade , Tomografia Computadorizada por Raios X
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