Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 11 de 11
Filter
1.
Int J Biol Macromol ; 202: 453-467, 2022 Mar 31.
Article in English | MEDLINE | ID: mdl-35031317

ABSTRACT

Electrohydrodynamic processing (EHDP) allows the use of a wide range of biopolymers and solvents, including food-grade biopolymers and green solvents, for the development of micro- and nanostructures. These structures present a high surface-area-to-volume ratio and different shapes and morphologies. The aim of this work was to design and produce hydroxypropyl methylcellulose (HPMC)-based micro- and nanostructures through EHD processing using green solvents, while exploring the influence of process and solution parameters, and incorporating a bioactive extracted from a food by-product. Low (LMW) and high (HMW) molecular weight HPMC have been used as polymers. The design-of-experiments methodology was used to determine the effects of process parameters (polymer concentration, flow rate, tip-to-collector distance, and voltage) of EHDP on the particle and fibre diameter, aspect ratio, diameter distribution, aspect ratio distribution, and percentage of fibre breakage. Additionally, melanoidins extracted from spent coffee grounds were encapsulated into the HPCM-based structures at a concentration of 2.5 mg melanoidins/mL of the polymer solution. Polymer solutions were characterised regarding their viscosity, surface tension and conductivity, and showed that the incorporation of melanoidins increased the viscosity and conductivity values of the polymer solutions. The developed structures were characterised regarding their thermal properties, crystallinity and morphology before and after melanoidin incorporation and it was observed that melanoidin incorporation did not significantly influence the characteristics of the produced micro- and nanostructures. Based on the results, it is possible to envision the use of the produced micro- and nanostructures in a wide range of applications, both in food and biomedical fields.


Subject(s)
Nanostructures , Polymers , Electric Conductivity , Hypromellose Derivatives , Polymers/chemistry
2.
Sci Total Environ ; 705: 135843, 2020 Feb 25.
Article in English | MEDLINE | ID: mdl-31822414

ABSTRACT

Wildfires affect vast areas of Mediterranean forests, thereby triggering changes in hydrological and geomorphological processes that can negatively affect both terrestrial and aquatic ecosystems. Although several studies have evaluated the post-fire hydrological and erosive response in burnt forest areas, an important knowledge gap remains with respect to nutrient mobilization by overland flow. To address this gap, a recently burnt area was selected near the Ermida village (north-central Portugal). The study area was instrumented shortly after a wildfire that occurred in July 2010, to evaluate the export of dissolved (nitrate - NO3-N and orthophosphate - PO4-P) and total nitrogen (TN) and phosphorus (TP) forms by overland flow. This was done in two burnt eucalyptus plantations due to their contrasting slope aspects (south-east vs. north-west). Bounded micro-plots were installed in August 2010 and monitored over two years. During this period, overland flow samples were collected on a 1- to 2-weekly basis, depending on the occurrence of rain. Results showed that the north west-facing slope (BE-N) presented higher nutrient losses than the south east-facing slope (BE-S), contradicting the findings of previous studies in the Mediterranean region. A logging operation that had taken place at the BE-N site shortly before the fire might account for these findings, by causing soil compaction and/or reducing the protective vegetation and litter cover. TN and TP exports were particularly pronounced during the first four months following the wildfire. After this initial period, further peaks in TN and TP exports occurred sporadically, mainly associated to intense rainfall events. The observed mid-term post-fire nutrient losses not only suggested a threat to the soil nutrient balance of Mediterranean eucalypt forests but also a potential risk of eutrophication of downstream water bodies.


Subject(s)
Nitrogen/analysis , Phosphorus/analysis , Ecosystem , Mediterranean Region , Portugal
3.
Sci Total Environ ; 551-552: 631-9, 2016 May 01.
Article in English | MEDLINE | ID: mdl-26897406

ABSTRACT

Over the past decades, wildfires have affected vast areas of Mediterranean ecosystems leading to a variety of negative on- and off-site environmental impacts. Research on fire-affected areas has given more attention to sediment losses by fire-enhanced overland flow than to nutrient exports, especially in the Mediterranean region. To address this knowledge gap for post-fire losses of phosphorus (P) by overland flow, a recently burnt forest area in north-central Portugal was selected and instrumented immediately after a wildfire. Three slopes were selected for their contrasting forest types (eucalypt vs. pine) and parent materials (granite vs. schist). The selected study sites were a eucalypt site on granite (BEG), a eucalypt site on schist (BES) and a maritime pine site on schist (BPS). Micro-plots were monitored over a period of six months, i.e. till the construction of terraces for reforestation obliged to the removal of the plots. During this 6-month period, overland flow samples were collected at 1- to 2-weekly intervals, depending on rainfall. Total P and PO4-P losses differed markedly between the two types of forests on schist, being lower at the pine site than at the eucalypt site, probably due to the presence of a protective layer of pine needle cast. Parent material did not play an important role in PO4-P losses by overland flow but it did in TP losses, with significantly lower values at the eucalypt site on granite than that on schist. These differences in TP losses can be attributed to the coarser texture of granite soils, typically promoting infiltration and decreasing runoff. The present findings provided further insights into the spatial and temporal patterns of post-fire soil nutrient losses in fire-prone forest types during the initial stages of the window-of-disturbance, which can be useful for defining post-fire emergency measures to reduce the risk of soil fertility losses.

4.
Sci Total Environ ; 572: 1281-1288, 2016 Dec 01.
Article in English | MEDLINE | ID: mdl-26765507

ABSTRACT

Over the past decades, wildfires have affected extensive areas of the Mediterranean region with negative impacts on the environment. Most of the studies on fire-affected areas have focused on sediment losses by overland flow, whereas few have addressed post-fire nutrient export. The present study aimed to address this research gap by assessing nitrogen (nitrate and total nitrogen) losses by overland flow in a recently burnt area in north-central Portugal. To this end, three burnt slopes were selected for their contrasting forest types (eucalypt vs. pine) and parent materials (granite vs. schist). The selected study sites were a eucalypt site on granite (BEG), a eucalypt site on schist (BES) and a maritime pine site on schist (BPS). Overland flow samples were collected during the first six months after the wildfire on a 1- to 2-weekly basis, after which this study had to be cancelled due to bench terracing of some of the sites. A peak in total nitrogen concentrations was observed in burnt areas immediately after the first post-fire rainfall event as a response to the erosion of the N-enriched ash layer. After this initial peak, smaller peaks were observed throughout the study period, mainly as a response to overland flow and/or erosion events. Nitrogen export differed strikingly between the two types of forests on schist, being higher at the eucalypt than at the pine site, due to the lack of a protective soil layer. Parent material did not play an important role on nitrogen export by overland flow since no significant differences were found between the eucalypt sites on granite and schist. The present study provides some insight into the differences in post-fire soil fertility losses between forest types and parent materials in the Mediterranean region, which is crucial information for defining post-fire land management measures to reduce soil degradation.

5.
J Food Sci Technol ; 52(12): 8292-9, 2015 Dec.
Article in English | MEDLINE | ID: mdl-26604406

ABSTRACT

In this work five sources of galactomannans, Adenanthera pavonina, Cyamopsis tetragonolobus, Caesalpinia pulcherrima, Ceratonia siliqua and Sophora japonica, presenting mannose/galactose ratios of 1.3, 1.7, 2.9, 3.4 and 5.6, respectively, were used to produce galactomannan-based films. These films were characterized in terms of: water vapour, oxygen and carbon dioxide permeabilities (WVP, O 2 P and CO 2 P); moisture content, water solubility, contact angle, elongation-at-break (EB), tensile strength (TS) and glass transition temperature (T g ). Results showed that films properties vary according to the galactomannan source (different galactose distribution) and their mannose/galactose ratio. Water affinity of mannan and galactose chains and the intermolecular interactions of mannose backbone should also be considered being factors that affect films' properties. This work has shown that knowing mannose/galactose ratio of galactomannans is possible to foresee galactomannan-based edible films properties.

6.
Sci Total Environ ; 524-525: 201-12, 2015 Aug 15.
Article in English | MEDLINE | ID: mdl-25897728

ABSTRACT

The current fire regime in the Mediterranean Basin constitutes a serious threat to natural ecosystems because it drastically enhances surface runoff and soil erosion in the affected areas. Besides soil particles themselves, soil cations can be lost by fire-enhanced overland flow, increasing the risk of fertility loss of the typically shallow and nutrient poor Mediterranean soils. Although the importance of cations for land-use sustainability is widely recognized, cation losses by post-fire runoff have received little research attention. The present study aimed to address this research gap by assessing total exports of Na(+), K(+), Ca(2+) and Mg(2+) in a recently burnt forest area in north-central Portugal. These exports were compared for two types of planted forest (eucalypt vs. maritime pine plantations), two types of parent materials (schist vs. granite) and for two spatial scales (micro-plot vs. hill slope). The study sites were a eucalypt plantation on granite (BEG), a eucalypt plantation on schist (BES) and a maritime pine plantation on schist (BPS). Overland flow samples were collected during the first six months after the wildfire. Cation losses differed strikingly between the two forest types on schist, being higher at the eucalypt than pine site. This difference was evident at both spatial scales, and probably due to the extensive cover of a needle cast from the scorched pine crowns. The role of parent material in cation export was less straightforward as it varied with spatial scale. Cation losses were higher for the eucalypt plantation on schist than for that on granite at the micro-plot scale, whereas the reverse was observed at the hill slope scale. Finally, cation yields were higher at the micro-plot than slope scale, in agreement with the general notion of scaling-effect in runoff generation.


Subject(s)
Cations/analysis , Environmental Monitoring , Fires , Forests , Conservation of Natural Resources , Ecosystem , Portugal
7.
Eur J Cancer Care (Engl) ; 24(6): 929-37, 2015 Nov.
Article in English | MEDLINE | ID: mdl-25752993

ABSTRACT

Focal cryoablation (FC), brachytherapy (B) and active surveillance (AS) were offered to patients diagnosed with very low-risk prostate cancer (VLRPC) in an equal access protocol. Comprehensive validated self-report questionnaires accessed patients' erectile (IIEF-5) and voiding (IPSS) functions, Beck scales measured anxiety (BAI), hopelessness (BHS) and depression (BDI), SF-36 reflected patients' quality of life added to the emotional thermometers including five visual analogue scales (distress, anxiety, depression, anger and need for help). Kruskal-Wallis or ANOVA tests and Spearman's correlations were obtained among groups and studied variables. Thirty patients were included, median follow-up 18 months (15-21). Those on AS (n = 11) were older, presented higher hopelessness (BHS) and lower general health perceptions (SF-36) scores than patients opting for FC (n = 10) and B (n = 9), P = 0.0014, P = 0.0268 and P = 0.0168 respectively. Patients on B had higher IPSS scores compared to those under FC and AC, P = 0.0223. For all 30 included patients, Spearman's correlation (rs ) was very strong between BHS and general health perceptions (rs  = -0.800, P < 0.0001), and weak/moderate between age and BHS (rs  = 0.405, P = 0.026) and age and general health perceptions (rs  = -0.564, P = 0.001). The sample power was >60%. To be considered in patients' counselling and care, current study supports the hypothesis that even VLRPC when untreated undermines psychosocial domains.


Subject(s)
Anxiety/psychology , Brachytherapy/psychology , Cryosurgery/psychology , Depression/psychology , Prostatic Neoplasms/psychology , Stress, Psychological/psychology , Watchful Waiting , Aged , Anger , Digital Rectal Examination , Disease Management , Erectile Dysfunction , Health Status , Hope , Humans , Kallikreins/blood , Magnetic Resonance Imaging , Male , Middle Aged , Prostate-Specific Antigen/blood , Prostatic Neoplasms/blood , Prostatic Neoplasms/diagnostic imaging , Prostatic Neoplasms/therapy , Quality of Life , Surveys and Questionnaires , Urination Disorders
8.
Environ Monit Assess ; 142(1-3): 325-35, 2008 Jul.
Article in English | MEDLINE | ID: mdl-17882523

ABSTRACT

The Antuã River, located in northwestern Portugal, drains a region with a high population density and a strong economic dynamism. These factors, together with a lack of facilities for appropriate treatment of domestic and industrial sewage, are putting increasing pressure on water resources. In this context, the aim of the present study was to identify point sources of pollution and to assess the surface water quality in the Antuã basin by monitoring physicochemical variables. A total of 40 point sources of wastewater, including some with a high pollution load, were detected in the most populated and industrialized areas of the São João da Madeira and Oliveira de Azeméis municipalities. These sources explained the strong degradation of water quality observed in the upper and medium Antuã River and in one of its tributaries, where maxima of 49 mg l(-1) for biochemical oxygen demand, 29 mg l(-1) for Kjeldahl nitrogen and 3.7 mg l(-1) for total phosphorus, were found after five surface water monitoring campaigns. Despite the relevance of pollution problems, a considerable water quality improvement, promoted by favourable reaeration conditions, was observed in the final stretch of the river, giving evidence of a great self-depuration capacity. However, the Antuã is a significant contributor of nutrients to the Ria de Aveiro, the coastal lagoon where the river meets the Atlantic Ocean.


Subject(s)
Environmental Monitoring/methods , Rivers/chemistry , Water Pollution, Chemical/analysis , Portugal , Rain
9.
Environ Monit Assess ; 111(1-3): 297-306, 2005 Dec.
Article in English | MEDLINE | ID: mdl-16311833

ABSTRACT

The aim of this study was to evaluate the water quality of the Cértima River basin (Central Portugal). For that purpose, surface water samples were collected in March, May and July 2003, at 10 selected sampling sites, and were analysed for physicochemical parameters, namely temperature, conductivity, pH, total suspended solids, dissolved oxygen, biochemical oxygen demand (BOD(5)), Kjeldahl nitrogen and total phosphorus. Results revealed an acceptable water quality during the spring season. Maxima of 64 mg dm(-3) for BOD(5), 39 mg dm(-3) for Kjeldahl nitrogen, and 5.2 mg dm(-3) for total phosphorus, were recorded during summer, indicating a significant degradation of the water quality in a river stretch located downstream of the town of Mealhada. These values, which did not comply with the objectives of minimum quality for surface waters prescribed by the Portuguese legislation, were related to domestic wastewater discharges and runoff waters from a cattle farm. Besides their effects on the middle stretch of the river, these pollution sources were the most likely cause of the high nutrient load in downstream waters, and thus may have a major impact on the trophic status of Pateira de Fermentelos, a sensitive wetland area located in the lower Cértima basin.


Subject(s)
Rivers , Water Pollutants, Chemical/analysis , Animal Husbandry , Animals , Cattle , Environmental Monitoring , Hydrogen-Ion Concentration , Nitrogen/analysis , Oxygen/analysis , Phosphorus/analysis , Portugal , Sewage , Temperature , Water Movements
10.
Sci Total Environ ; 313(1-3): 49-60, 2003 Sep 01.
Article in English | MEDLINE | ID: mdl-12922060

ABSTRACT

Atmospheric concentrations of volatile organic compounds were measured at two rural sites in central Portugal. The sites were chosen to be in line with the summer northwesterly sea breezes in order to study the evolution of the chemical composition of air masses during transport to inland areas. The most abundant non-oxygenated hydrocarbon in the ambient air was isoprene and the monoterpenes alpha-pinene, beta-pinene and 1,8 cineol. The maximum isoprene levels (6-7 ppb) were recorded at the most inland site, suggesting an enrichment of coastal air masses with biogenic emissions during transport over eucalyptus forests. Formaldehyde was the most prominent carbonyl compound in the atmosphere but acetaldehyde and acrolein were also abundant. Concentrations of carbonyl compounds had a tendency to be higher inland, particularly for glyoxal, methyl glyoxal, methyl vinyl ketone, metacrolein and pentanal. The observed increases indicate that carbonyls were produced by photochemical oxidation of biogenic hydrocarbons in aged air masses with coastal origin. Isoprene, monoterpenes and various carbonyls exhibited pronounced diurnal variations, which are explained on the basis of emissions from vegetation, oxidation pathways of biogenic hydrocarbons and meteorological conditions.


Subject(s)
Environmental Monitoring , Hydrocarbons/analysis , Agriculture , Plants , Portugal , Volatilization
11.
Arq Neuropsiquiatr ; 54(4): 595-600, 1996 Dec.
Article in Portuguese | MEDLINE | ID: mdl-9201340

ABSTRACT

Myotonia is the phenomenon of decrease of muscular relaxation rate, after either a contraction or a mechanical or electrical stimulus. Congenital myotonias are hereditary affections and do not present muscular dystrophy. The current trend is to group them as ionic channels diseases, together with the periodic paralysis. The authors accompanied the cases of seven patients, six males and one female, with ages ranging from 16 to 48 years (average 27 years) and onset of symptoms between 1 and 10 years (average 5 years). These patients presented a myotonic phenomenon unleashed by intensive contraction and global muscular hypertrophy. Three patients were diagnosed as cases of Becker type generalized myotonia because they presented a recessive autosomic heredity and/or transient episodes of muscular weakness. Two patients fitted the description of Thomsen congenital myotonia, with a pattern of dominating autosomic heredity and/or absence of weakness episodes or worsening factors for their condition. Two patients presented fluctuating myotonia, which because worse in cold weather or at potassium intake. The clinical diagnosis was confirmed through complementary tests (electroneuromyography, muscle biopsy and DNA study). Each of the patients made use of different drugs, in the search of optimal lessening of their myotonia. There were five reports of amelioration with the use of diphenilhydantoine; one report with the use of carbamazepine; three reports with the use of acetazolamide; one report with the use of a calcium channel blocker; one report with the use of a beta-adrenergic; one report with the use of thiazide; and none with the use of quinidine/procainamide.


Subject(s)
Myotonia Congenita/diagnosis , Adolescent , Adult , Female , Humans , Male , Middle Aged , Myotonia Congenita/drug therapy
SELECTION OF CITATIONS
SEARCH DETAIL
...