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131.
The setting of back-up zones in distance relays has to deal with fault current infeeds between the relay and remote faults. Traditional approaches to this problem are conservative, some times leaving portions of a power system without sensitive or selective back-up protection. In this paper, a probabilistic model for the relay errors resulting from the variation of the infeeds is developed. Other measurement inaccuracies are also considered in order to build a probabilistic approach to setting all zones of distance relays. The developed concepts are associated to automatic tools for computer aided protection coordination and applied to the Portuguese transmission grid 相似文献
132.
Mnica Mendes Fbris Kossoski Ana I. Lozano Joo Pereira-da-Silva Rodrigo Rodrigues Joo Ameixa Nykola C. Jones Sren V. Hoffmann Filipe Ferreira da Silva 《International journal of molecular sciences》2021,22(12)
We report absolute photoabsorption cross sections for gas-phase 2- and 5-bromopyrimidine in the 3.7–10.8 eV energy range, in a joint theoretical and experimental study. The measurements were carried out using high-resolution vacuum ultraviolet synchrotron radiation, with quantum chemical calculations performed through the nuclear ensemble approach in combination with time-dependent density functional theory, along with additional Franck–Condon Herzberg–Teller calculations for the first absorption band (3.7–4.6 eV). The cross sections of both bromopyrimidines are very similar below 7.3 eV, deviating more substantially from each other at higher energies. In the 7.3–9.0 eV range where the maximum cross-section is found, a single and broad band is observed for 5-bromopyrimidine, while more discernible features appear in the case of 2-bromopyrimidine. Several π* ← π transitions account for the most intense bands, while weaker ones are assigned to transitions involving the nitrogen and bromine lone pairs, the antibonding σ*Br orbital, and the lower-lying Rydberg states. A detailed comparison with the available photo-absorption data of bromobenzene is also reported. We have found significant differences regarding the main absorption band, which is more peaked in bromobenzene, becoming broader and shifting to higher energies in both bromopyrimidines. In addition, there is a significant suppression of vibrational structures and of Rydberg states in the pair of isomers, most noticeably for 2-bromopyrimidine. 相似文献
133.
3-D Container Packing Heuristics 总被引:5,自引:0,他引:5
In this paper, we study the 3-D container packing problem. The problem is divided into box selection, space selection, box orientation and new space generation sub-problems. As a first step, a basic heuristic is devised. From results using this heuristic, problems are categorized as homogeneous and heterogeneous. Two augmenting heuristics are then formulated to deal with these categories. They are complementary in their capabilities in dealing with a range of practical problems, and in terms of their computational consumption. Results using our algorithmsexceed the benchmark by 4.5% on average. 相似文献
134.
Selecting Al Alloys for Light Weight Heat Exchanger Fins Aluminium usage for heat exchangers for the motor car industry has increased significantly in recent years. The intrinsic advantage of aluminium alloys has enabled the replacement of traditional heat exchanger materials such as brass and copper. Alloy development has enabled the aluminium industry to prepare a range of alloys in different conditions and gauges that can meet the requirements of heat exchanger designers. This paper refers to the background for choice of available alloys and to development trends on a fitness for purpose basis. 相似文献
135.
Albuquerque Gabriela B. M. L. Silva Valdir P. Rodrigues Joo Paulo C. 《Fire Technology》2022,58(2):737-775
Fire Technology - Reinforced concrete beams lose resistance at high temperatures and so as to guarantee their good performance, it is mandatory to consider this accidental action in design. As an... 相似文献
136.
Dr. Ricardo Ferraz Prof. João Costa‐Rodrigues Prof. Maria H. Fernandes Dr. Miguel M. Santos Dr. Isabel M. Marrucho Prof. Luís Paulo N. Rebelo Prof. Cristina Prudêncio Prof. João Paulo Noronha Dr. Željko Petrovski Dr. Luís C. Branco 《ChemMedChem》2015,10(9):1480-1483
Significant antiproliferative effects against various tumor cell lines were observed with novel ampicillin salts as ionic liquids. The combination of anionic ampicillin with appropriate ammonium, imidazolium, phosphonium, and pyridinium cations yielded active pharmaceutical ingredient ionic liquids (API‐ILs) that show potent antiproliferative activities against five different human cancer cell lines: T47D (breast), PC3 (prostate), HepG2 (liver), MG63 (osteosarcoma), and RKO (colon). Some API‐ILs showed IC50 values between 5 and 42 nM , activities that stand in dramatic contrast to the negligible cytotoxic activity level shown by the ampicillin sodium salt. Moreover, very low cytotoxicity against two primary cell lines—skin (SF) and gingival fibroblasts (GF)—indicates that the majority of these API‐ILs are nontoxic to normal human cell lines. The most promising combination of antitumor activity and low toxicity toward healthy cells was observed for the 1‐hydroxyethyl‐3‐methylimidazolium–ampicillin pair ([C2OHMIM][Amp]), making this the most suitable lead API‐IL for future studies. 相似文献
137.
Caio L. C. Carvalho Anna T. B. Silva Lucyano J. A. Macedo Roberto A. S. Luz José M. Moita Neto Ubirajara P. Rodrigues Filho Welter Cantanhêde 《International journal of molecular sciences》2015,16(7):14594-14607
Supramolecular self-assembly has been demonstrated to be a useful approach to developing new functional nanomaterials. In this work, we used a cobalt Prussian blue analogue (PBA, Co3[Co(CN)6]2) compound and a β-cyclodextrin (CD) macrocycle to develop a novel host-guest PBA-CD nanomaterial. The preparation of the functional magnetic material involved the self-assembly of CD molecules onto a PBA surface by a co-precipitation method. According to transmission electronic microscopy results, PBA-CD exhibited a polydisperse structure composed of 3D nanocubes with a mean edge length of 85 nm, which became shorter after CD incorporation. The supramolecular arrangement and structural, crystalline and thermal properties of the hybrid material were studied in detail by vibrational and electronic spectroscopies and X-ray diffraction. The cyclic voltammogram of the hybrid material in a 0.1 mol·L−1 NaCl supporting electrolyte exhibited a quasi-reversible redox process, attributed to Co2+/Co3+ conversion, with an E1/2 value of 0.46 V (vs. SCE), with higher reversibility observed for the system in the presence of CD. The standard rate constants for PBA and PBA-CD were determined to be 0.07 and 0.13 s−1, respectively, which suggests that the interaction between the nanocubes and CD at the supramolecular level improves electron transfer. We expect that the properties observed for the hybrid material make it a potential candidate for (bio)sensing designs with a desirable capability for drug delivery. 相似文献
138.
Different bacterial models for in vitro induction of non‐cavitated enamel caries‐like lesions: Microhardness and polarized light miscroscopy analyses 下载免费PDF全文
Priscila Hernández De Campos Mariane Emi Sanabe Jonas Almeida Rodrigues Danilo Antonio Duarte Maria Teresa Botti Rodrigues Santos Renata Oliveira Guaré cristiane Duque Adrian Lussi Michele Baffi Diniz 《Microscopy research and technique》2015,78(6):444-451
The aim of this study was to compare different bacterial models for in vitro induction of non‐cavitated enamel caries‐like lesions by microhardness and polarized light microscopy analyses. One hundred blocks of bovine enamel were randomly divided into four groups (n = 25) according to the bacterial model for caries induction: (A) Streptococcus mutans, (B) S. mutans and Lactobacillus acidophilus, (C) S. mutans and L. casei, and (D) S. mutans, L. acidophilus, and L. casei. Within each group, the blocks were randomly divided into five subgroups according to the duration of the period of caries induction (4–20 days). The enamel blocks were immersed in cariogenic solution containing the microorganisms, which was changed every 48 h. Groups C and D presented lower surface hardness values (SMH) and higher area of hardness loss (ΔS) after the cariogenic challenge than groups A and B (P < 0.05). As regards lesion depth, under polarized light microscopy, group A presented significantly lower values, and groups C and D the highest values. Group B showed a higher value than group A (P < 0.05). Groups A and B exhibited subsurface caries lesions after all treatment durations, while groups C and D presented erosion‐type lesions with surface softening. The model using S. mutans, whether or not it was associated with L. acidophilus, was less aggressive and may be used for the induction of non‐cavitated enamel caries‐like lesions. The optimal period for inducing caries‐like lesions was 8 days. Microsc. Res. Tech. 78:444–451, 2015. © 2015 Wiley Periodicals, Inc. 相似文献
139.
Bruno R. S. Paula Davila Zampieri J. Augusto R. Rodrigues Paulo J. S. Moran 《Advanced Synthesis \u0026amp; Catalysis》2016,358(22):3555-3571
(Z)‐3‐Acetoxymethyl‐4‐R‐3‐buten‐2‐ones (R=aryl, alkyl) and (Z)‐3‐methyl‐4‐R‐3‐buten‐2‐ones (R=aryl) were synthesized and submitted to reduction by the yeast Saccharomyces cerevisiae producing the (R)‐ and (S)‐4‐R‐3‐methybutan‐2‐ones, respectively. This stereochemistry control strategy was applied in the syntheses of (R)‐ and (S)‐Tropional® with moderate to high enantiomeric excesses. Other (Z)‐3‐acyloxymethyl‐4‐phenyl‐3‐buten‐2‐ones showed similar behavior to the (Z)‐3‐acetoxymethyl counterpart, and the acylated Morita–Baylis–Hillman adduct 1‐acetoxy‐2‐methylene‐1‐phenylbutan‐3‐one produced a mixture of products, with and without the acetoxy group, via three different reaction pathways. In addition to experiments employing whole cells, those in which isolated enereductases were used suggested that the main pathway through which the loss of the acetoxy group occurs during the biocatalytic cascade is an SN2′‐type reaction, rather than formal hydrogen addition followed by acetic acid elimination. Finally, related ethyl enones were reduced enantioselectively by the yeast Candida albicans, producing both (R)‐ and (S)‐reduction products, depending on the presence of the acetoxy group in the starting material.
140.
Chemical, Microbiological, and Sensory Quality of Cod Products Salted in Different Brines 总被引:1,自引:0,他引:1
Maria J. Rodrigues Peter Ho Maria E. López-Caballero Narcisa M. Bandarra Maria L. Nunes 《Journal of food science》2005,70(1):M1-M6
ABSTRACT: Studies were carried out on the effect of different brines containing high concentrations of calcium chloride (CaCl2 , 0.8%w/w), magnesium chloride (MgCl2 , 0.4%w/w), and potassium chloride (KCl, 50%) on the chemical (chloride and moisture contents), microbial (total viable counts, total coliforms, enterococci, and staphylococci), and sensory quality of salted cod. The brines were prepared from combinations of the Ca, Mg, and K ions and sodium chloride (NaCl) at pH 6.5 and 8.5. Additionally, 3 salts (one composed solely of NaCl, another commercial sea salt from the southern Europe and, finally, a natural salt from northern Europe) were also tested. Principal component analysis structured the chemical and microbiology data in 3 clusters: (1) an extreme cluster, formed by cod brined in the commercial sea salt, which achieved the highest microbiological counts, namely 4.1 log CFU/g on plate count agar (PCA) and 1250 coliforms/g; (2) an intermediate cluster composed of cod salted in brine containing 50% NaCl, 0.4% MgCl2 , and 49.6% KCl (pH 6.5); and (3) a central cluster, including all the other treatments, which presented the lowest microbiological counts, namely 2.4 log CFU/g on PCA and 20 coliforms/g. Although the batches of the intermediate cluster presented slightly higher total viable and staphylococci counts than the central cluster, the presence of Mg and K ions improved the color of the salted product. In the assayed concentrations, CaCl2 , MgCl2 , and KCl can be used in the brining of cod without adversely affecting the microbiological and sensory quality of the salted cod. 相似文献