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81.
Ali Mortezaei Marcelo Godoy Simões Fernando Pinhabel Marafão Josep M. Guerrero Ahmed Al Durra Tiago Davi Curi Busarello 《电力部件与系统》2017,45(8):864-880
This paper investigates selective sharing of load current components among the parallel operation of distributed generators (DGs) in three-phase four-wire stand-alone microgrids. The proposed control method is based on master-slave operation of DGs, and the goal of selective sharing of load current components is to have DGs located in close proximity of the load operating in slave mode, in order to inject their available energy and also compensate the non-active load current components, while the distant DGs might operate in master mode to share the remaining load autonomously. Droop control is employed due to impracticality of communication at remote nodes, and resistive line impedance compensation is adopted to decouple active and reactive power controllers and ensure proper active power sharing among master DGs, irrespective of the mitigation of non-active current components by the slave inverters. The sharing factors for each current component are determined by a higher level control. The Conservative Power Theory (CPT) decompositions provide decoupled power and current references for the inverters, resulting in a selective sharing strategy. The principles supporting the developed control strategy are discussed, and the effectiveness of the control is demonstrated through computational simulations using PSIM software. 相似文献
82.
Tiago Pinheiro Braga Ant?nio Narcísio Pinheiro W. T. Herrera Y. T. Xing E. Baggio-Saitovitch Antoninho Valentini 《Journal of Materials Science》2011,46(3):766-773
Iron oxide nanoparticles dispersed in aluminum (Al) or silicon (Si) oxides were prepared via a polymeric precursor derived
from the Pechini method. The samples were characterized by thermogravimetric analysis, Fourier-transform infrared spectroscopy,
X-ray diffraction, N2 adsorption/desorption isotherms (Brunauer–Emmett–Teller, BET), M?ssbauer spectroscopy, and vibrating sample magnetometry
(VSM). BET analysis shows that the samples are mesoporous materials and have a high surface area. The size of the Fe2O3 nanoparticles in Al2O3 is smaller than that in SiO2. M?ssbauer spectra of the samples show that the Fe2O3 nanoparticles in Al2O3 are non-magnetic at room temperature but magnetic below 50 K. The FeSi samples are magnetic at both room and low temperatures.
The magnetic measurements with VSM confirmed this point. 相似文献
83.
Catarina M. Morais Ana M. Cardoso Ana Rita D. Araújo Ana Reis Pedro Domingues Maria Rosrio M. Domingues Maria C. Pedroso de Lima Amlia S. Jurado 《International journal of molecular sciences》2022,23(21)
Modulation of lipid metabolism is a well-established cancer hallmark, and SCD1 has been recognized as a key enzyme in promoting cancer cell growth, including in glioblastoma (GBM), the deadliest brain tumor and a paradigm of cancer resistance. The central goal of this work was to identify, by MS, the phospholipidome alterations resulting from the silencing of SCD1 in human GBM cells, in order to implement an innovative therapy to fight GBM cell resistance. With this purpose, RNAi technology was employed, and low serum-containing medium was used to mimic nutrient deficiency conditions, at which SCD1 is overexpressed. Besides the expected increase in the saturated to unsaturated fatty acid ratio in SCD1 silenced-GBM cells, a striking increase in polyunsaturated chains, particularly in phosphatidylethanolamine and cardiolipin species, was noticed and tentatively correlated with an increase in autophagy (evidenced by the increase in LC3BII/I ratio). The contribution of autophagy to mitigate the impact of SCD1 silencing on GBM cell viability and growth, whose modest inhibition could be correlated with the maintenance of energetically associated mitochondria, was evidenced by using autophagy inhibitors. In conclusion, SCD1 silencing could constitute an important tool to halt GBM resistance to the available treatments, especially when coupled with a mitochondria disrupter chemotherapeutic. 相似文献
84.
JH Morais Cabral A Lee SL Cohen BT Chait M Li R Mackinnon 《Canadian Metallurgical Quarterly》1998,95(5):649-655
More and more elderly subjects are offered for pulmonary resection. The object of this study was to review the results of excision for cancer in octogenarians. PATIENTS: 51 consecutive patients (44 men, 7 women) with a mean age of 82 years (80-91) were operated on. 31 lobectomies, 2 bilobectomies, 13 pneumonectomies, 1 segmental resection and 4 exploratory thoracotomies were carried out. 17 tumours were classed as stage I, 15 as stage II and 15 as stage III. RESULTS: 38 patients (75%) had uncomplicated post-operative periods; the predicted factors for complication were the existence of weight loss and alteration of respiratory function. 2 patients (4%) died in the post-operative phase. Neither the type of operation, the staging or the existence of cardiovascular dysfunction had any influence on the post-operative phase. The level of the survival at 3 and 5 years was 39% and 16% respectively. 30% of the late deaths were related to intercurrent events. CONCLUSIONS: Pulmonary excision may be envisaged in an octogenarian who is in good physical and intellectual state with a limited tumour. This surgery in general is applied to a population which probably only marginally consists of octogenarians but the results here justify their inclusion in the indications for selection. 相似文献
85.
The interplay of transverse and longitudinal fluctuations of a stripe is analyzed using bosonization techniques. We show the existence of a charge-density-wave instability for quarter-filled stripes if the underlying lattice potential has a zigzag symmetry. Our results are in accordance with the observation of static stripes formation in underdoped La2–x–y
Nd
y
Sr
X
CuO4 exactly at the onset of the low-temperature-tetragonal transition. 相似文献
86.
Cristiane MS Barbosa Harriman A Morais Fernanda M Delvivo Herman S Mansur Mnica C De Oliveira Marialice PC Silvestre 《Journal of the science of food and agriculture》2004,84(14):1891-1900
Some reaction parameters were tested in the hydrolysis of casein by papain, in order to prepare hydrolysates with high oligopeptide contents, for either dietetic or pharmaceutical purposes. Five casein hydrolysates were prepared and then fractionated by size‐exclusion HPLC. The rapid correct fraction area method was used for quantifying peptides and free amino acids. Among the five reaction conditions tested, three produced similar peptide profiles. However, the use of a temperature of 37°C and an E:S ratio of 2% is probably the most economical condition for use in large‐scale manufacture. With the aim of masking the bitterness of these preparations, a new method, based on the encapsulation in lipospheres, was used. Also, second derivative spectrophotometry was used for the first time to measure the extent of encapsulation of protein hydrolysates, which changed from 50% to 83%. Moreover, the efficiency of this system was evaluated by analysing other parameters, which showed a reduction of hydrophobicity and bitterness of all samples, as well as good chemical stability during 60 days of storage under refrigeration. The electron microscopical analysis of liposheres showed an average size around 5.0 ± 1.0 µm. Copyright © 2004 Society of Chemical Industry 相似文献
87.
Tiago M. Dias Daniel F. Ferber Cid C. de Souza Arnaldo V. Moura 《International Transactions in Operational Research》2003,10(3):245-265
Several heuristics, based on evolutive algorithms and local search, are used to solve the nurse scheduling problem at a large hospital. Due to several intricate and specific restrictions imposed on the schedules, the problem is a difficult one to solve by hand. Moreover, some of the restrictions have a subjective value attached to them, and this constrains the use of exact methods that search for global optima. In order to facilitate the use of the solver modules by the hospital staff, a user interface was also implemented. 相似文献
88.
This paper describes the development and implementation of a tool for the diagnosis of faults in power transformers through the analysis of dissolved gases in oil. The computational system approach is based on the combined use of some traditional criteria of the dissolved gas analysis published in standards, an artificial neural network, and a fuzzy logic system. The objective of the tool is to provide the user with an answer obtained from analysis not only of the traditional methods already consolidated in the technical literature, but also via artificial-intelligence techniques, reaching a higher degree of reliability with respect to each technique individually. The results obtained with this tool are promising in the diagnosis of incipient faults in transformers, reaching success levels of more than 80%. 相似文献
89.
A lateral flow immunoassay (LFIA) was developed in the competitive reaction format and applied to test sulphathiazole (STZ) residues in honey samples. To prepare the assay test, a hapten conjugate and goat antirabbit antiserum as capture and control reagent, respectively, were dispensed on nitrocellulose membrane. Polyclonal antiserum against sulphathiazole was conjugated to colloidal gold nanoparticles and used as the detection reagent. The visual limit of detection (cut-off value) of the sulphathiazole LFIA was 15 ng/g, reaching qualitative results within 10 min. The assay was evaluated with STZ spiked honey samples from different geographical origins (n = 25). The results were in good agreement with those obtained from liquid chromatography separation and mass spectroscopy detection (LC–MS), indicating that the LFIA test might be used as a qualitative method for the determination of sulphathiazole residues without expensive equipment. The test was also highly specific, showing no cross-reactivity to other chemically similar antibiotics. To our knowledge, this is the only work where a development of LFIA tests for the detection of sulphathiazole residues is performed. 相似文献
90.
Adriana Andrade Carvalho Daiane Finger Christiane Schinieder Machado Eduardo Morgado Schmidt Patrícia Marçal da Costa Ana Paula Negreiros Nunes Alves Thamires Maria Fontenele Morais Maria Goretti Rodrigues de Queiroz Sueli Pércio Quináia Marcos Roberto da Rosa Julio Murilo Trevas dos Santos Cláudia Pessoa Manoel Odorico de Moraes Letícia Veras Costa-Lotufo Alexandra Christine Helena Frankland Sawaya Marcos Nogueira Eberlin Yohandra Reyes Torres 《Food chemistry》2011
The present study aimed to evaluate in vivo and in vitro the antitumoural activity of a propolis extract obtained with edible vegetable oil and its fractions and also to investigate its chemical composition by LC–MS and LC–MS/MS. To evaluate the toxicological aspects related to the propolis extract treatment, hematological, biochemical, histopathological and morphological analyses of treated animals were performed. All propolis extracts showed an in vivo antitumour activity in the experimental model with a moderate toxicity effect at experimental exposure levels. The oil extract was as effective as the ethanolic extract at inhibiting tumour growth. In vitro assays showed that the whole oil extract produced better inhibition of tumour cells than its fractions. LC–MS and LC–MS/MS identified four phenolic acids and three flavonoids. The anticancer potential of the oil extract of propolis has been demonstrated and the edible vegetable oil was shown as an attractive alternative solvent to extract bioactive natural propolis components. 相似文献