In this paper, the five parameters of the solar cell single-diode model are analytical and quasi-explicitly extracted for the first time, just using the coordinates of four arbitrary points of the ...characteristic I–V curve and the slopes of the curve in these points. The new method presented, called Analytical and Quasi-Explicit (AQE) method, is exact because no simplifications of the model nor a priori approximations of the parameters are used and, it is quasi-explicit in the sense that all the parameters except one are explicitly given. The unique parameter not explicitly computed is easily obtained by solving a five-degree polynomial equation. Accurate and practical conditions are provided to select which solution of the previous equation is the desired parameter.
It is also introduced a very easy method to obtain, directly from real data measurements, the needed four points of the I–V curve as well as the slopes in these points, without using any kind of sophisticated techniques.
Finally, some experimental results are presented to demonstrate the high accuracy and simplicity of the new method. The results are compared with the well-known analytical five-point method and the recent oblique asymptote method.
Preventing intimate partner violence or dating violence (DV) among adolescents is a public health priority due to its magnitude and damaging short and long-term consequences for adolescent and adult ...health. In our study protocol, we complement prior experiences in DV prevention by promoting protective factors (or assets) against gender violence such as communication skills, empathy and problem-solving capability through "Cinema Voice", a participatory educational intervention based on adolescents' strengths to tackle DV.
A longitudinal quasi-experimental educational intervention addressed to boys and girls ages 13-17 years, enrolled in secondary education schools in Alicante (Spain), Rome (Italy), Cardiff (UK), Iasi (Romania), Poznan (Poland) and Matosinhos (Portugal). Both process and results evaluations will be carried out with 100-120 intervention and 120-150 control group students per city at three time periods: before, after and 6 months after the implementation of the following interventions: 1) Training seminar with teachers to promote knowledge and skills on the core issues of intervention; 2) Workshops with intervention groups, where participants produce their own digital content presenting their perspective on DV; and 3) Short film exhibitions with participants, their families, authorities and other stakeholders with the objective of share the results and engage the community. Outcome measures are self-perceived social support, machismo, sexism, tolerance towards gender violence, social problem-solving and assertiveness as well as involvement in bullying/cyberbullying. Other socio-demographic, attitudes and violence-related co-variables were also included.
This study may provide relevant information about the effectiveness of educational interventions that combine a positive youth development framework with educational awareness about the importance of achieving gender equality and preventing and combating gender violence. To our knowledge, this is the first study that involves six European countries in an educational intervention to promote violence protective assets among enrolled adolescents in secondary schools. This study may provide the needed tools to replicate the experience in other contexts and other countries.
Clinicaltrials.gov: NCT03411564 . Unique Protocol ID: 776905. Date registered: 18-01-2018.
This paper presents a practical implementation of a photovoltaic I-V curves and maximum power point estimation algorithm (IVMPPE). The IVMPPE estimates the I-V curve and sets the operation of the ...solar panels at a voltage that extracts the maximum available power without tracking. The operation is based on solving the parameters of the solar array equivalent electrical model, in real time, only with the measurements of six voltage and current coordinates near the operating point. Moreover, the strategy for selecting the measured points and the discard procedures for incorrect estimated curves are also detailed. To validate the IVMPPE, it has been tested under different operating conditions, and its accuracy has been compared with the classical perturb and observe (P&O) technique. The distinguishing feature of the IVMPPE is that complete I-V model is obtained, not only the MPP, enlarging the capabilities to other fields, e.g., real-time monitoring and prediction.
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•Maleinized hempseed oil (MHO) increases toughness of polylatcide (PLA).•MHO increases thermal stability of PLA.•MHO contributes to high environmentally friendly PLA formulations.•MHO ...minimizes cold crystallization of PLA.•MHO gives balanced mechanical resistance and ductility to PLA.
The present study describes the effect of maleinized hemp seed oil (MHO) on the physical performance of polylactide (PLA) pieces. To this end, PLA pieces with varying MHO contents in the 0–10 wt% range were manufactured by twin-screw extrusion (TSE) followed by injection molding. The resultant pieces were characterized in terms of their mechanical, thermal, and thermomechanical properties. The obtained properties suggested that, unlike typical plasticizers, MHO does not only induce an increment in elongation at break and impact resistance but it also enhances both elastic modulus and tensile strength. In addition, a moderate decrease in the glass transition temperature (Tg) was observed. This was ascribed to simultaneous linear chain-extension, branching, and/or cross-linking phenomena due to the reaction of the multiple maleic anhydride (MAH) groups present in MHO with the terminal hydroxyl groups of the PLA chains. Furthermore, morphology characterization revealed that, though certain phase separation occurred at its highest content, MHO was finely dispersed as submicron droplets within the PLA matrix contributing to improving toughness. The use of multi-functionalized reactive vegetable oils thus represents a highly sustainable solution to reduce the intrinsic brittleness of PLA materials without compromising their mechanical resistance and the toughened biopolymer pieces described herein can find interesting applications in, for instance, rigid packaging.
In this work, low pressure glow discharge O2 plasma has been used to increase wettability in a LDPE film in order to improve adhesion properties and make it useful for technical applications. Surface ...energy values have been estimated using contact angle measurements for different exposure times and different test liquids. In addition, plasma-treated samples have been subjected to an aging process to determine the durability of the plasma treatment. Characterization of the surface changes due to the plasma treatment has been carried out by means of Fourier transformed infrared spectroscopy (FTIR) to determine the presence of polar species such as carbonyl, carboxyl and hydroxyl groups. In addition to this, atomic force microscopy (AFM) analysis has been used to evaluate changes in surface morphology and roughness. Furthermore, and considering the semicrystalline nature of the LDPE film, a calorimetric study using differential scanning calorimetry (DSC) has been carried out to determine changes in crystallinity and degradation temperatures induced by the plasma treatment. The results show that low pressure O2 plasma improves wettability in LDPE films and no significant changes can be observed at longer exposure times. Nevertheless, we can observe that short exposure times to low pressure O2 plasma promote the formation of some polar species on the exposed surface and longer exposure times cause slight abrasion on LDPE films as observed by the little increase in surface roughness.
To explore the effect of the school feeding program purchase criteria on the quantity, variety and origin of food products acquired for school meals in a municipality in Brazil.
Analysis of purchase ...lists for two years prior and two years after implementation of the purchase criteria (2010). The origin (family farms (FF)/other providers (OP)) and nutritional characteristics (recommended/controlled) of food products were studied, registering annual varieties (n) and daily quantities (kg/day); contrast of proportions was applied.
The acquisition of recommended products increased, and the quantity of controlled products decreased (p = 0.005). Purchase of legumes and vegetables (p < 0.05) increased and high sugar foods decreased (p = 0.02). The majority of food products in 2010 and 2011 were acquired from OP (64% and 61%), although FF provided the greatest proportion of legumes and vegetables. Ten new varieties of recommended products were incorporated, 9 of which were acquired from FF.
The criteria of direct purchase from family farms resulted in an increase in the variety and quantity of healthy foods in the schools in the municipality.
•The criteria of direct purchase of food from local family farms contributes to increases in quantity and variety of healthy foods.•The direct purchase from local farmers can promote healthy feeding programs in schools.
Background and AimsThis study aims to determine the role that both direct effects of fire and subsequent daily temperature fluctuations play in the seed bank dynamics of obligate seeders from the ...Mediterranean Basin. The short yet high soil temperatures experienced due to passage of fire are conflated with the lower, but longer, temperatures experienced by daily fluctuations which occur after removing vegetation. These germination cues are able to break seed dormancy, but it is difficult to assess their specific level of influence because they occur consecutively after summer fires, just before the flush of germination in the wet season (autumn).MethodsBy applying experimental fires, seed treatments were imposed that combined fire exposure/non-fire exposure with exposure to microhabitats under a gradient of disturbance (i.e. gaps opened by fire, mechanical brushing and intact vegetation). The seeds used were representative of the main families of obligate seeders (Ulex parviflorus, Cistus albidus and Rosmarinus officinalis). Specifically, an assessment was made of (1) the proportion of seeds killed by fire, (2) seedling emergence under field conditions and (3) seeds which remained ungerminated in soil.Key ResultsFor the three species studied, the factors that most influenced seedling emergence and seeds remaining ungerminated were microhabitats with higher temperature fluctuations after fire (gaps opened by fire and brushing treatments). The direct effect of fire decreased the seedling emergence of U. parviflorus and reduced the proportion of seeds of R. officinalis remaining ungerminated.ConclusionsThe relevance of depleting vegetation (and subsequent daily temperature fluctuation in summer) suggests that studies focusing on lower temperature thresholds for breaking seed dormancy are required. This fact also supports the hypothesis that the seeding capacity in Mediterranean Basin obligate seeders may have evolved as a response to a wide range of disturbances, and not exclusively to fire.
Superoxide dismutases (SODs) are antioxidant enzymes that protect cells from oxidation. Three SODs have been identified in mammals, but there is limited information in teleosts. This study ...investigates SODs in the European eel and their expression patterns during testis maturation. Phylogenetic and synteny analyses revealed SODs paralogs and their evolution in vertebrates. The eel possesses one SOD1 and two SOD2/3 (a and b), indicating SOD2 and SOD3 duplication in elopomorphs. SODs expression were then evaluated in various male and female tissues. SOD1 is more expressed in females, while SOD2a and SOD2b dominate brain-pituitary-gonad tissues in both sexes. SOD3a showed predominant expression in the ovary and the male livers, whereas SOD3b was found in the pituitary and brain of both sexes. The effects of different maturation protocols (standard hormonal treatment vs. same protocol preceded with cold seawater pre-treatment) on SODs expression during testis maturation were evaluated. Salinity increase at the onset of standard treatment at 20 °C, simulating early migration, upregulated SOD1, SOD2a, and SOD2b, coinciding with spermatogonia type A differentiated cells dominance. Thereafter, SOD2a and SOD3a decreased, while SOD2b increased during hormonal treatment-induced spermatogenesis. Pre-treatment with seawater at 10 °C, mimicking the conditions at the beginning of the seawater migration, downregulated SOD1 but increased SOD3a expression. Finally, the standard hormonal treatment, replicating spawning at higher temperatures, downregulated SOD1 in eels without any pre-treatment while SOD2a expression increased in pre-treated eels. This study revealed tissue-specific, sex-dependent, and maturation-related SOD expression patterns, predicting SODs dynamic expression profiles during their reproductive migration.
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•Phylogenetic and synteny analyses enabled to identify five SOD genes in the European eel;•Tissue-specific and gender-dependent SODs expression was found;•Different SODs expression patterns were observed through eel spermatogenesis;•Temperature and/or salinity influenced SODs levels at the testis level.
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