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81.
82.
Ana Isabel Gonzlez-Hernndez Loredana Scalschi Begonya Vicedo Emilio Luis Marcos-Barbero Rosa Morcuende Gemma Camaes 《International journal of molecular sciences》2022,23(6)
Putrescine (Put) is the starting point of the polyamines (PAs) pathway and the most common PA in higher plants. It is synthesized by two main pathways (from ornithine and arginine), but recently a third pathway from citrulline was reported in sesame plants. There is strong evidence that Put may play a crucial role not only in plant growth and development but also in the tolerance responses to the major stresses affecting crop production. The main strategies to investigate the involvement of PA in plant systems are based on the application of competitive inhibitors, exogenous PAs treatments, and the most efficient approaches based on mutant and transgenic plants. Thus, in this article, the recent advances in understanding the role of this metabolite in plant growth promotion and protection against abiotic and biotic stresses will be discussed to provide an overview for future research. 相似文献
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84.
Composition and behaviour of cerium films on galvanised steel 总被引:9,自引:0,他引:9
The composition and corrosion performance of galvanised steel treated by immersion in cerium nitrate solution was investigated by electrochemical techniques and surface analysis. The surface film consists of a mixture of Ce(III) and Ce(IV) compounds, being very rich in Ce(III) in the first instants of the deposition process and becoming gradually enriched in the more oxidised form, Ce(IV). The presence of this film on the surface hinders the corrosion reaction by reducing the rate of both the cathodic and the anodic reactions. The film becomes thicker but more uneven when the time of film growth increases, with the development of defects in the film, which in contact with electrolyte behaves anodic with respect to the covered areas of the surface. These thicker films have revealed lower resistance to corrosion initiation. 相似文献
85.
Fabrício A.M. Moura José R. Camacho Marcelo L.R. Chaves Geraldo C. Guimarães 《Electric Power Systems Research》2010
The main task in this paper is to present a performance analysis of a distribution network in the presence of an independent power producer (IP) synchronous generator with its speed governor and voltage regulator modeled using TACS – Transient Analysis of Control Systems, for distributed generation studies. Regulators were implemented through their transfer functions in the S domain. However, since ATP-EMTP (Electromagnetic Transient Program) works in the time domain, a discretization is necessary to return the TACS output to time domain. It must be highlighted that this generator is driven by a steam turbine, and the whole system with regulators and the equivalent of the power authority system at the common coupling point (CCP) are modeled in the “ATP-EMTP – Alternative Transients Program”. 相似文献
86.
Members of Aspergillus section Nigri are distributed worldwide, being considered as common food spoilage fungi. Some species of this section produce ochratoxin A (OTA), mainly Aspergillus carbonarius and several members of the Aspergillus niger aggregate. Detection of ochratoxigenic A. niger aggregate strains is important to prevent OTA contamination in foodstuffs. A new Real Time PCR procedure has been developed for the rapid and specific detection and quantification of ochratoxin A-producing strains of the A. niger aggregate. Two specific primers delimiting a 120 bp fragment and a probe were designed and directed to a polyketide synthase (PKS) from A. niger CBS 513.88 genome. This PKS has a strong similarity to PKS of A. ochraceus fragment involved in ochratoxin biosynthesis. Specificity was confirmed by testing primers towards purified DNA from 91 fungal strains, including reference and food isolates. The SYBR-Green and the TaqMan approaches developed allowed the specific detection only of ochratoxigenic strains of the A. niger aggregate. All other analyzed food related fungi gave negative results. This is the first report on a Real Time PCR system for the detection of OTA-producing strains of the A. niger aggregate. 相似文献
87.
João M. M. Ferra Adélio M. Mendes Mário Rui N. Costa Luisa H. Carvalho Fernão D. Magalhães 《应用聚合物科学杂志》2010,118(4):1956-1968
Urea‐formaldehyde (UF) resins present a swollen colloidal phase dispersed within a continuous water phase containing soluble oligomers. The main goal of the present investigation is to clarify the physical and chemical nature of those two phases and elucidate their impact on the bonding process. Optical and electronic microscopy has provided information on the morphology of the colloidal phase, showing primary particles and particle agglomerates. Mechanisms are suggested for the colloidal stabilization and dilution‐induced flocculation. Three commercial UF resins with different F/U molar ratios were studied using particle size distribution (PSD) analysis. The results showed the influence of the resin's degree of condensation and the aging status on the size of the colloidal structures. Gel permeation chromatography analysis was performed on samples of different resins and of the respective continuous and dispersed phases, separated by centrifugation. The quantified fraction of insoluble molecular aggregates present in the chromatograms was related to the resins synthesis conditions and age. Differential scanning calorimetry and tensile shear strength tests were performed to evaluate the reactivity and adhesive performance of each phase. It is suggested that the colloidal phase acts as a reactive filler at the wood joint interfaces, contributing for the resins bonding performance. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 相似文献
88.
Ana Paula Rodrigues Brasil Sebastio Tavares de Rezende Maria do Carmo Gouveia Pelúzio Valria Monteze Guimares 《Food chemistry》2010,118(2):251-255
The objectives of this work were to establish a safe and economically viable process for the removal of raffinose oligosaccharides (RO) from soy flour and compare the effects of RO elimination from diets with regard to nutritional parameters by testing in Wistar rats. Debaryomyces hansenii UFV-1 was cultivated in suspension of defatted soy flour (1:10 w/v). An increase in α-galactosidase activity was observed in the medium, with a consequent decrease in the RO concentration. A total reduction of RO was achieved at 36 h of incubation. The diet containing soy flour free of RO presented higher digestibility, 91.28%, in relation to the diet containing soy flour with RO, 87.14%. However, the removal of the oligosaccharides from the diet did not promote a significant improvement in the values of weight gain, and other nutritional parameters tested on rats, during the experimental period of 14 days. 相似文献
89.
90.
Nuno Lopes Paulo Vila Real Luís Simões da Silva Jean-Marc Franssen 《Fire Technology》2010,46(1):91-108
In this paper, the structural response of stainless steel thin-walled elements submitted to fire is analysed numerically by
means of the geometrically and materially non-linear Finite Element program SAFIR, including imperfections. In order to make
these simulations, two main changes in the program were made: (i) the code was changed in order to deal with the stainless
steel 2D material constitutive law to be used with shell elements and (ii) the possibility of the program to take into account
residual stresses with shell finite elements was introduced. The stainless steel stress–strain relationship at high temperatures
was based on the one presented in part 1.2 of Eurocode 3. To model the strain hardening exhibited by the stainless steels,
using the shell element formulation, an approximation to the Eurocode 3 constitutive law was needed. Local and global geometrical
imperfections were considered in the simulations. The paper shows the influence of the residual stresses on the ultimate load-carrying
capacity of thin-walled stainless steel structural elements in case of fire. 相似文献