3,322 research outputs found
Simple and efficient furfural production from xylose in media containing 1-Butyl-3-Methylimidazolium hydrogen sulfate
The acidic 1-butyl-3-methylimidazolium hydrogen sulfate ([bmim][HSO4]) ionic liquid was explored as both a reaction medium and a catalyst in the furfural production from xylose. Preliminary experiments were carried out at 100–140 °C for 15–480 min in systems containing just xylose dissolved in [bmim][HSO4] in the absence of externally added catalysts. More than 95% xylose conversion was achieved when operating at 120 or 140 °C for 300 and 90 min, respectively; but just 36.7% of the initial xylose was converted to furfural. Operation in biphasic reaction systems (in the presence of toluene, methyl-isobutyl ketone or dioxane as extraction solvents) at 140 °C under selected conditions resulted in improved furfural production (73.8%, 80.3%, and 82.2% xylose conversion to furfural for the cited extraction solvents, respectively)
Quantification and mapping of coastal flooding extension for Bissau, Guinea-Bissau: a climate change scenario perspective
RESUMO: A inundação costeira (IC) constitui um dos impactos mais
significativos da elevação do nível do mar (ENM) resultante das alterações
climáticas.Acidade de Bissau, que alberga ~25% da população da Guiné-Bissau,
já é afetada pela IC devido às marés e tempestades, esperando-se um
agravamento devido à ENM. Este artigo avaliou a vulnerabilidade à IC em
cenário de ENM na cidade de Bissau, através do modelo de superfície de
inundação única, considerando um valor único de inundação, aquireferido como
nível total de água (NTA) e uma superfície topográfica.Aextensão da inundação
foi quantificada e cartografada usando o NTA estimado para 2100 (5,2 m). Os
resultados indicam que a área potencialmente inundada corresponde a 29,3%
do total da área de estudo. A zona Sudoeste da cidade é a mais exposta à
inundação, devido à baixa altitude e ocupação desordenada de terrenos, tornando
esta região mais vulnerável num cenário de alterações climáticas.ABSTRACT: Coastal flooding (CF), enhanced by climate change, is one of
the most significant impacts of sea level rise (SLR). Bissau city, home to
~25% of Guinea-Bissau population is already affected by CF due to tides
and storms. It is anticipated that the situation will deteriorate in coming
decades with the expected scenarios of SLR. This article evaluated the
vulnerability to coastal flooding of Bissau, using the single-value model,
which considers two variables: inundation value and a topographic surface.
The inundation value, here referred as total water level (TWL) was
estimated by the sum of three vertical components: astronomical tide (AT),
storm surge (SS) and the SLR estimation for the considered scenario. Thus,
the inundation extension was quantified and mapped using a TWL estimated
for the year 2100, and a high-precision global Digital Elevation Model
(DEM – TanDEM-X) of the Bissau region. The results indicate that the land
potentially to be flooded corresponds to 29.3% of the study area (94.9 km²).
The Southwest zone of Bissau presents greater exposure to flooding, due
to its low altitude. Also, the disorderly anthropogenic occupation of flooded
lands, makes these areas more vulnerable in a climate change scenario.info:eu-repo/semantics/publishedVersio
Quantificação e cartografia da extensão de inundação costeira em Bissau, Guiné-Bissau: perspetiva em cenário de alterações climáticas
Coastal flooding (CF), enhanced by climate change, is one of
the most significant impacts of sea level rise (SLR). Bissau city, home to
~25% of Guinea-Bissau population is already affected by CF due to tides
and storms. It is anticipated that the situation will deteriorate in coming
decades with the expected scenarios of SLR. This article evaluated the
vulnerability to coastal flooding of Bissau, using the single-value model,
which considers two variables: inundation value and a topographic surface.
The inundation value, here referred as total water level (TWL) was
estimated by the sum of three vertical components: astronomical tide (AT),
storm surge (SS) and the SLR estimation for the considered scenario. Thus,
the inundation extension was quantified and mapped using a TWL estimated
for the year 2100, and a high-precision global Digital Elevation Model
(DEM – TanDEM-X) of the Bissau region. The results indicate that the land
potentially to be flooded corresponds to 29.3% of the study area (94.9 km²).
The Southwest zone of Bissau presents greater exposure to flooding, due
to its low altitude. Also, the disorderly anthropogenic occupation of flooded
lands, makes these areas more vulnerable in a climate change scenario.info:eu-repo/semantics/publishedVersio
Positron annihilation and constant photocurrent method measurements on a-Si:H films: A comparative approach to defect identification
Defect structure of hydrogenated amorphous silicon thin-films was studied by positron annihilation spectroscopy (PAS), whereas the density of states below the Fermi level was measured by constant photocurrent method (CPM). Divacancies and large vacancy clusters were identified as the main defects present in these films, with relative concentrations strongly dependent on the rf-power. Correlation between PAS, CPM results and I(V) characteristics of solar cells suggests the creation of energy levels above the Fermi energy, not observable by CPM, related to large vacancy clusters.http://www.sciencedirect.com/science/article/B6TVT-4JX373P-2/1/af7c69b0fdf17cefb2432fb357d5d86
Excess of naturally occurring fluoride in groundwater discharge in Macaronesia: Brava Island, Cape Verde
A high concentration of fluoride in groundwater poses a risk to human health. One of the best-known problems related to excess fluoride in drinking water is dental fluorosis. The characteristic composition of volcanic rocks in oceanic islands tends to present high concentrations of fluoride in groundwater discharge in springs. This study investigates fluoride content in two springs (Encontro and Ferreiros) on the island of Brava (Cape Verde), with the objective of monitoring the operational control production and distribution of drinking water. Using a spectrophotometric method, the level of fluoride found in the water discharged from the Encontro spring was found to be in the range of 4.8 to 6.5 mg/L, whereas at the Ferreiros spring, it was 5.8 to 6.2 mg/L. These results are far above the threshold limit established in the decree No. 5 of 2017 of the Cape Verdean legislation, whose legal threshold value for fluoride is 1.5 mg/L, the same value established by the World Health Organization (WHO). Due to geological conditions and consequences for the health of the population, the water is not adequate for consumption without proper treatment.info:eu-repo/semantics/publishedVersio
Population Structure and Reproduction of Pseudione elongata africana (Bopyridae, Isopoda)
The population structure and reproductive fitness of Pseudione elongata africana parasitizing the shrimp Palaemon concinnus were studied in two mangroves in Mozambique. About 100 host specimens were sampled every 15 days for 12 months at Costa do Sol, a peri-urban mangrove near Maputo, and at Saco, a near pristine mangrove at Inhaca Island. Parasites were removed from the branchiostegites of the shrimp and measured. Ovigerous females were selected and the eggs and embryos removed from the brood pouch and counted after staging their level of development. At Costa do Sol, the total length of female parasites (FPTL) was about 17% higher than at Saco. Ovigerous females were also more abundant at Costa do Sol in both the dry and wet seasons. The average brood size ranged from 89 to 207 eggs mm-1 FPTL in the Saco and 177 to 357 eggs mm-1 at Costa do Sol. These data provide baseline information on the population structure and reproduction of this parasite in east African mangroves. Comparative data on these parameters in peri-urban and more isolated mangroves may also lay the groundwork for the use of parasite reproduction as an indicator of anthropogenic pressure
Modelling of micro-sources for security studies
International audienceThe interconnection of small, modular generation and storage technologies at the MV and LV distribution level have the potential to significantly impact power system performance. In this paper models of the main micro-generation sources are described. In particular, the models of Microturbines, Fuel Cells, Photovoltaic Systems and Wind Turbines, are described. In addition basic models of their power electronic interfaces are given. The integration of the above models in a steady state and dynamic simulation tool, which is developed in the framework of the EU funded MICROGRIDS project, will provide a simulation test platform, which will be necessary to define and evaluate the developed operational and control strategies
Guidelines for Maritime Spatial Planning in the European Macaronesia: Stakeholder-oriented
Macaronesian Maritime Spatial Planning - MarSPMAMAR-S
The impact of metabolic syndrome on metabolic, pro-inflammatory and prothrombotic markers according to the presence of high blood pressure criterion
OBJECTIVES: We explored whether high blood pressure is associated with metabolic, inflammatory and prothrombotic dysregulation in patients with metabolic syndrome. METHODS: We evaluated 135 consecutive overweight/obese patients. From this group, we selected 75 patients who were not under the regular use of medications for metabolic syndrome as defined by the current Expert Panel on Detection, Evaluation and Treatment of High Blood Cholesterol in Adults criteria. The patients were divided into metabolic syndrome with and without high blood pressure criteria (≥130/≥85 mmHg). RESULTS: Compared to the 45 metabolic syndrome patients without high blood pressure, the 30 patients with metabolic syndrome and high blood pressure had significantly higher glucose, insulin, homeostasis model assessment insulin resistance index, total cholesterol, low-density lipoprotein-cholesterol, triglycerides, uric acid and creatinine values; in contrast, these patients had significantly lower high-density lipoprotein-cholesterol values. Metabolic syndrome patients with high blood pressure also had significantly higher levels of retinol-binding protein 4, plasminogen activator inhibitor 1, interleukin 6 and monocyte chemoattractant protein 1 and lower levels of adiponectin. Moreover, patients with metabolic syndrome and high blood pressure had increased surrogate markers of sympathetic activity and decreased baroreflex sensitivity. Logistic regression analysis showed that high-density lipoprotein, retinol-binding protein 4 and plasminogen activator inhibitor-1 levels were independently associated with metabolic syndrome patients with high blood pressure. There is a strong trend for an independent association between metabolic syndrome patients with high blood pressure and glucose levels. CONCLUSIONS: High blood pressure, which may be related to the autonomic dysfunction, is associated with metabolic, inflammatory and prothrombotic dysregulation in patients with metabolic syndrome
Tradeoffs in the quest for climate smart agricultural intensification in Mato Grosso, Brazil.
Low productivity cattle ranching, with its linkages to rural poverty, deforestation and greenhouse gas (GHG) emissions, remains one of the largest sustainability challenges in Brazil and has impacts worldwide. There is a nearly universal call to intensify extensive beef cattle production systems to spare land for crop production and nature and to meet Brazil?s Intended Nationally Determined Contribution to reducing global climate change. However, different interventions aimed at the intensification of livestock systems in Brazil may involve substantial social and environmental tradeoffs. Here we examine these tradeoffs using a whole-farm model calibrated for the Brazilian agricultural frontier state ofMato Grosso, one of the largest soybean and beef cattle production regions in the world. Specifically, we compare the costs and benefits of a typical extensive, continuously grazed cattle system relative to a specialized soybean production system and two improved cattle management strategies (rotational grazing and integrated soybean-cattle) under different climate scenarios.We found clear tradeoffs in GHG and nitrogen emissions, climate resilience, and water and energy use across these systems. Relative to continuously grazed or rotationally grazed cattle systems, the integreated soybean-cattle system showed higher food production and lower GHG emissions per unit of human digestible protein, as well as increased resilience under climate change (both in terms of productivity and financial returns). All systems suffered productivity and profitability losses under severe climate change, highlighting the need for climate smart agricultural development strategies in the region. By underscoring the economic feasibility of improving the performance of cattle systems, and by quantifying the tradeoffs of each option, our results are useful for directing agricultural and climate policy
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