Explicit group USSOR method for solving elliptic partial differential equations

This paper presents a new 4-points Explicit Group Unsymmetric Successive Overrelaxation (USSOR) iterative method to approximate the solution of the linear systems derived from the discretisation of self-adjoint elliptic partial equations. Several studies have been carried out by many researchers on the USSOR iterative method, for example, the analysis of its convergence [1], an upper bound for its error [2] and recently a special case of the USSOR, namely the SSOR method has been used to approximate the solution of augmented systems [4] and [8]. The computational behaviour of this new method and a comparison with its point version is presented

A 31P nuclear magnetic resonance study of phosphate levels in roots of ectomycorrhizal and nonmycorrhizal plants of Castanea sativa Mill.

31P-Nuclear Magnetic Resonance (NMR) was used to assess phosphate distribution in ectomycorrhizal and nonmycorrhizal roots of Castanea sativa Mill. as well as in the mycorrhizal fungus Pisolithus tinctorius in order to gain insight into phosphate trafficking in these systems. The fungus P. tinctorius accumulated high levels of polyphosphates during the rapid phase of growth. Mycorrhizal and nonmycorrhizal roots accumulate orthophosphate. Only mycorrhizal roots presented polyphosphates. The content in polyphosphates increased along the 3 months of mycorrhiza formation. In mycorrhizal roots of plants cultured under axenic conditions, the orthophosphate pool decreased along the culture time. In nonmycorrhizal roots the decrease in the orthophosphate content was less pronounced. The level of orthophosphate in mycorrhizal roots was significantly lower than in nonmycorrhizal ones, which indicates that this system relies upon the fungal polyphosphates as a major source of phosphate

The explicit group TOR method

The numerical methods for solving partial differential equations have been one of the significant achievements made possible by the digital computers. With the advent of parallel computers, many studies have been performed and a number of new techniques have been investigated in order to develop new methods that are suitable for these computers. One of these techniques is the explicit group iterative methods which have been extensively studied and analysed in the last two decades. The explicit group iterative methods for the numerical solution of self-adjoint elliptic partial differential equations have been introduced (Evans & Biggins, 1982; Yousif & Evans, 1986) and has been shown to be computationally superior in comparison with other iterative methods. These methods were found to be suitable for parallel computers as they possess independent tasks (Evans & Yousif, 1990). Martins, Yousif & Evans (2002) introduced a new explicit 4-points group accelerated overrelaxation (EGAOR) iterative method, a comparison with the point AOR method has shown its computational advantages. The point TOR method was developed and a number of papers related to the TOR method and its convergence have been presented (Kuang & Ji, 1988; Chang, 1996; Chang, 2001; Martins, Trigo & Evans 2003). In this paper, we formulate a new group method from the TOR family, the explicit 4-points group overrrelaxation (EGTOR) iterative method, the derivation of the new method is presented. Numerical experiments have been carried out and the results obtained confirm the superiority of the new method when compared to the point TOR method

A variant of the AOR method for augmented systems

A variant of the AOR method for augmented system

Atividade antioxidante e antimicrobiana de extratos de plantas de Pterospartum tridentatum (L.) Willk. in vitro e silvestres

Atividade antioxidante e antimicrobiana de extratos de plantas de Pterospartum tridentatum (L.) Willk. in vitro e silvestres.info:eu-repo/semantics/publishedVersio

Natural extracts from Pterospartum tridentatum at different vegetative stages: extraction yiels, phenolic content and antioxidant activity

The aerial parts of Pterospartum tridentatum, a wild growing species in Portugal used in traditional medicine and gastronomy, were harvested at different stages (vegetative phase, flowering phase and beginning of dormancy) in two locations in Portugal (Malcata and Gardunha mountains), and the respective aqueous extracts have been studied. The influence of the seasonal variation in the extraction yield, total phenolic content and antioxidant activity was evaluated. The extraction was carried out in boiling water in consecutive steps. After each step, the aqueous extract was separated and fresh water was added maintaining the same plant material. The procedure was repeated seven times, within an overall time period of 180 minutes. Higher extraction yields were achieved with plant stems collected at the vegetative phases, either from Malcata or Gardunha regions. The total phenolic content of the extracts from Malcata plants ranged from 273 mg to 400 mg gallic acid equivalent/g dry matter, which was quite similar to that determined for extracts from Gardunha (245 to 394 mg gallic acid equivalent/g dry matter). The antioxidant activity was determined by the radical scavenging activity method using 2,2-diphenyl-1-picrylhydrazyl radical (DPPH). The greatest radical scavenging activity was observed in the flowers extracts, even though all extracts produced presented a good antioxidant activity. Furthermore, the antioxidant activity was not affected by the exposure of the plant material at 100ºC for long periods of time (180 min). The results show that Pterospartum tridentatum has a great potential to be used as a new source of natural antioxidants for the food industry

Identificação de compostos bioativos em plantas silvestres e plantas in vitro de Pterospartum tridentatum (L.) Willk.

Identificação de compostos bioativos em plantas silvestres e plantas in vitro de Pterospartum tridentatum (L.) Willk.info:eu-repo/semantics/publishedVersio

Wild mushroom extracts potentiate the action of standard antibiotics against multi-resistant bacteria

The indiscriminate use of antibiotics and chemotherapeutic agents and the genetic ability of bacteria to transmit and acquire resistance resulted in the development of resistant species. In the last few years, several studies have been conducted in different countries to demonstrate the efficacy of natural products, not only studying their direct antimicrobial activity but also their capacity as resistance-modifying agents. The main objective of the present work was to evaluate the capacity of five wild mushroom extracts to potentiate the action of standard antibiotics, through synergisms that allow a decrease in their therapeutic doses and ultimately contribute to the reduction of resistances.The authors are grateful to Portuguese Foundation for Science and Technology (FCT) and COMPETE/QREN/EU for the financial support through the research project PTDC/AGR-ALI/110062/2009, and to CHTMAD – Hospital Center of Trás-os-Montes e Alto Douro and Siemens for all the supportinfo:eu-repo/semantics/publishedVersio

Total fat content and fatty acid profile of pseudocereals

Amaranth, quinoa, and buckwheat are called “pseudocereals” since they produce starch-rich seeds like cereals but they are dicotyledonous plants (and not monocotyledonous as cereals). According to some phylogenetic classifications, amaranth (Amaranthus) and quinoa (Chenopodium) genera belong to the order Caryophyllales, whereas buckwheat (Fagopyrum) belongs to Polygonales [1]. Pseudocereals have recently gained more popularity as a part of human diet thanks to their chemical composition, particularly as a source of protein, vitamins of B group, minerals and also for their gluten-free flour [2].The authors are grateful to the Foundation for Science and Technology (FCT, Portugal) and FEDER under Programme PT2020 for financial support to CIMO (UID/AGR/00690/2013); Roberts and Santa are also grateful to Latvia University of Agriculture and to the ERAMUS+ Mobility programme for the financial support.info:eu-repo/semantics/publishedVersio