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991.
José Elias Claudio Arroyo Ana Amélia de Souza Pereira 《The International Journal of Advanced Manufacturing Technology》2011,55(5-8):741-753
This paper presents a multi-objective greedy randomized adaptive search procedure (GRASP)-based heuristic for solving the permutation flowshop scheduling problem in order to minimize two and three objectives simultaneously: (1) makespan and maximum tardiness; (2) makespan, maximum tardiness, and total flowtime. GRASP is a competitive metaheuristic for solving combinatorial optimization problems. We have customized the basic concepts of GRASP algorithm to solve a multi-objective problem and a new algorithm named multi-objective GRASP algorithm is proposed. In order to find a variety of non-dominated solutions, the heuristic blends two typical approaches used in multi-objective optimization: scalarizing functions and Pareto dominance. For instances involving two machines, the heuristic is compared with a bi-objective branch-and-bound algorithm proposed in the literature. For instances involving up to 80 jobs and 20 machines, the non-dominated solutions obtained by the heuristic are compared with solutions obtained by multi-objective genetic algorithms from the literature. Computational results indicate that GRASP is a promising approach for multi-objective optimization. 相似文献
992.
993.
Fausto L. Catto T. Yonamine Claudio S. Kiminami Conrado R.M. Afonso Walter J. Botta Claudemiro Bolfarini 《Journal of Alloys and Compounds》2011
This paper describes results obtained by spray forming three iron-based alloys, namely [(Fe0.6Co0.4)0.75B0.2Si0.05]96Nb4, Fe65B30Nb4Ti1 and Fe63B29Nb4Ti4, whose compositions derive from rapid solidification studies, in an attempt to obtain metallic glasses. The [(Fe0.6Co0.4)0.75B0.2Si0.05]96Nb4 alloy presented higher glass-forming ability and showed a high fraction of amorphous phase formation up to a depth of 4 mm in the deposit. On the other hand, the spray formed deposits of the Fe65B30Nb4Ti1 and Fe63B29Nb4Ti4 alloys showed fully crystalline microstructure, despite the fact that the melt spun ribbons were fully amorphous. 相似文献
994.
Polyamides (PAs) containing fluorene, oxyether, and diphenyl‐silane moieties in the repeating unit were synthesized in > 85% yield by direct polycondesation between a diamine and four dicarboxylic acids. Alternatively, one PA was synthesized from an acid dichloride. The diamine 4‐[4‐[9‐[4‐(4‐aminophenoxy)‐3‐methyl‐phenyl]fluoren‐9‐yl]‐2‐methyl‐phenoxy]aniline ( 3 ) was obtained from the corresponding dinitro compound, which was synthesized by nucleophilic aromatic halogen displacement from p‐chloronitrobenzene and 9,9‐bis (4‐hydroxy‐3‐methyl‐phenyl)fluorene ( 1 ). Monomers and polymers were characterized by FTIR and 1H, 13C, and 29Si‐NMR spectroscopy and the results were in agreement with the proposed structures. PAs showed inherent viscosity values between 0.14 and 0.43 dL/g, indicative of low molecular weight species, probably of oligomeric nature. The glass transition temperature (Tg) values were observed in the 188–211°C range by DSC analysis. Thermal decomposition temperature (TDT10%) values were above 400°C due to the presence of the aromatic rings in the diamine. All PAs showed good transparency in the visible region (>88% at 400 nm) due to the incorporation of the fluorene moiety. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011 相似文献
995.
Stefano Giulitti Claudio Cinquemani Alberto Quaranta Sara Spilimbergo 《The Journal of Supercritical Fluids》2011,58(3):385-390
This article investigates the inactivation mechanism of high-pressure food treatment, considered as alternative to conventional biocidal processes. We aimed to determine intracellular pH decrease under CO2 and N2O pressure, so far postulated as one of the main causes of inactivation. Working with a lab-scale bioreactor in mild conditions – 25 °C and pressures up to 8 MPa – we monitored – for the first time during pressurization – cytoplasmic pH variations of Listeria innocua labeled with pH-sensitive fluorophores based on fluorescein.We show that carbonic acid, due to solubilization of CO2 into the aqueous phase, causes a rapid pH drop in the cytosol, reaching pH 4.8 at 1 MPa and falls below the detection limit of the indicator fluorophore of pH 4.0. This correlates with a reduced viability (below 90%) in all the pressure ranges investigated. Contrarily, treatment under N2O pressure reduces cell viability without significant pH-drop neither of intra- nor extra-cellular liquid at any pressure investigated. The pH value remains between 7 and 6 while an inactivation of more than 80% is achieved at 8 MPa.Our data clearly demonstrate that, as a critical pressure is achieved, microbial inactivation is mainly due to pressure-induced membrane permeation – stimulated by non-acidifying fluids as well, rather then cytoplasmic acidification, as widely argued so far. A definitive understanding of the microbial inactivation mechanism due to CO2/N2O under pressure has been advanced significantly. 相似文献
996.
Gianluca Gallo Magdalena Korsak Prof. Claudio Luchinat Dr. Jiafei Mao Dr. Enrico Ravera 《Chembiochem : a European journal of chemical biology》2013,14(14):1891-1897
The accumulation of soluble toxic beta‐amyloid (Aβ) aggregates is an attractive hypothesis for the role of this peptide in the pathology of Alzheimer's disease. We have introduced sedimentation through ultracentrifugation, either by magic angle spinning (in situ) or preparative ultracentrifuge (ex situ), to immobilize biomolecules and make them amenable for solid‐state NMR studies (SedNMR). In situ SedNMR is used here to address the kinetics of formation of soluble Aβ assemblies by monitoring the disappearance of the monomer and the appearance of the oligomers simultaneously. Ex situ SedNMR allows us to select different oligomeric species and to reveal atomic‐level structural features of soluble Aβ assemblies. 相似文献
997.
Claudio Pistidda Daphiny Pottmaier Fahim Karimi Sebastiano Garroni Agnieszka Rzeszutek Martin Tolkiehn Maximilian Fichtner Wiebke Lohstroh Marcello Baricco Thomas Klassen Martin Dornheim 《International Journal of Hydrogen Energy》2014
In this work the effect of the ratio of starting reactants on the hydrogen absorption reaction of the system xNaH + MgB2 is investigated. At a constant hydrogen pressure of 50 bar, depending on the amount of NaH present in the system NaH + MgB2, different hydrogen absorption behaviors are observed. For two system compositions: NaH + MgB2 and 0.5NaH + MgB2, the formation of NaBH4 and MgH2 as only crystalline hydrogenation products is achieved. The relation between the ratio of the starting reactants and the obtained hydrogenation products is discussed in detail. 相似文献
998.
Claudio Mura Stefania Fruci Pietro Lamia Miriam Cappello Sara Filippi 《Journal of Energetic Materials》2013,31(2):216-233
In azidic binders for solid propellants, the N3 functionality is introduced by substitution of a halogen or tosyl group, but recently the mesyl group has been suggested as an alternative. The mesylate group has two advantages, mainly related to its small dimensions and low cost. Poly(glycidyl azide) and poly 3-azidomethyl-3-methyl oxetane were prepared by using both tosylate and mesylate precursors. The azidation kinetics were studied at three different temperatures while keeping all other operating parameters the same. The results confirmed the good potential of the mesylate precursors for the production of azidic binders. 相似文献
999.
New processes in the environmental chemistry of nitrite: nitration of phenol upon nitrite photoinduced oxidation 总被引:1,自引:0,他引:1
The role of nitrite as an environmental factor has been widely recognized. Nitrite is a relevant source of *OH in the atmosphere, both in the gas phase via photolysis of gaseous HNO2 and in atmospheric hydrometeors by photolysis of NO2-. In aqueous systems, *OH production through nitrite photolysis can be negligible due to the competition for light absorption by dissolved Fe(III), colloidal iron oxides, and nitrate. These photoexcited oxidants interact with NO2- and HNO2 to form *NO2, either directly or via formation of *OH. As a consequence, nitrite and nitrous acid may act as *NO2 rather than *OH sources. The radical *NO2 is involved in the nitration of many aromatic compounds, of which phenol is a model in this work. Kinetic measurements using 2-propanol as *OH scavenger show that the direct production of *OH by aqueous Fe(III) species decreases as pH increases. At slightly acidic and neutral pH values, oxidation of nitrite occurs by direct electron transfer to photoexcited Fe(III)aq species or colloidal iron oxides, in addition to the *OH-mediated oxidation of NO2-. The reported findings suggest a completely new role of nitrite in aquatic environments. 相似文献
1000.
BACKGROUND: Coffee grounds and tea leaf wastes exhibit strong affinity for metals such as Fe and Zn. The objective of this experiment was to evaluate the effect of top‐dressing application of Fe‐ and Zn‐enriched coffee grounds and tea leaf wastes at the panicle initiation stage on the mineral content of rice grains and the yield of paddy rice. RESULTS: The Fe and Zn contents of brown rice grains increased significantly on application of both coffee and tea waste materials. The concentration of Mn was increased by top‐dressing application of coffee waste material only. For Cu, no significant (P < 0.05) differences were found between the control and ferrous sulfate/zinc sulfate treatment. The application of coffee and tea waste materials led to a significant (P < 0.05) increase in the number of grains per panicle, which was reflected in increases in the total number of grains per hill and in grain yield. CONCLUSION: The top‐dressing application of these materials is an excellent method to recycle coffee grounds and tea wastes from coffee shops. Use of these novel materials would not only reduce the waste going to landfill but would also benefit the mineral nutrition of rice consumers at low cost by increasing Fe and Zn levels of rice grains as well as grain yield. Copyright © 2011 Society of Chemical Industry 相似文献