Tramp Ship Scheduling Problem with Berth Allocation Considerations and Time-dependent Constraints

This work presents a model for the Tramp Ship Scheduling problem including berth allocation considerations, motivated by a real case of a shipping company. The aim is to determine the travel schedule for each vessel considering multiple docking and multiple time windows at the berths. This work is innovative due to the consideration of both spatial and temporal attributes during the scheduling process. The resulting model is formulated as a mixed-integer linear programming problem, and a heuristic method to deal with multiple vessel schedules is also presented. Numerical experimentation is performed to highlight the benefits of the proposed approach and the applicability of the heuristic. Conclusions and recommendations for further research are provided.Comment: 16 pages, 3 figures, 5 tables, proceedings paper of Mexican International Conference on Artificial Intelligence (MICAI) 201

Attaching DNA to Nanoceria: Regulating Oxidase Activity and Fluorescence Quenching

This document is the Accepted Manuscript version of a Published Work that appeared in final form in Applied Materials and Interfaces copyright © American Chemical Society after peer review and technical editing by publisher. To access the final edited and published work see Pautler, R., Kelly, E. Y., Huang, P.-J. J., Cao, J., Liu, B., & Liu, J. (2013). Attaching DNA to Nanoceria: Regulating Oxidase Activity and Fluorescence Quenching. ACS Applied Materials & Interfaces, 5(15), 6820–6825. https://doi.org/10.1021/am4018863Cerium oxide nanoparticles (nanoceria) have recently emerged as a nanozyme with oxidase activity. In this work, we present a few important interfacial properties of nanoceria. First, the surface charge of nanoceria can be controlled not only by adjusting pH but also by adsorption of simple inorganic anions. Adsorption of phosphate and citrate gives negatively charged surface over a broad pH range. Second, nanoceria adsorbs DNA via the DNA phosphate backbone in a sequence-independent manner; DNA adsorption inhibits its oxidase activity. Other anionic polymers display much weaker inhibition effects. Adsorption of simple inorganic phosphate does not have the inhibition effect. Third, nanoceria is a quencher for many fluorophores. These discoveries provide an important understanding for further use of nanoceria in biosensor development, materials science, and nanotechnology.University of Waterloo || Canadian Foundation for Innovation || Natural Sciences and Engineering Research Council || Ontario Ministry of Research and Innovation |

Cerium Oxide Nanoparticles Protect Cardiac Progenitor Cells from Oxidative Stress

Cardiac progenitor cells (CPCs) are a promising autologous source of cells for cardiac regenerative medicine. However, CPC culture in vitro requires the presence of microenvironmental conditions (a complex array of bioactive substance concentration, mechanostructural factors, and physicochemical factors) closely mimicking the natural cell surrounding in vivo, including the capability to uphold reactive oxygen species (ROS) within physiological levels in vitro. Cerium oxide nanoparticles (nanoceria) are redox-active and could represent a potent tool to control the oxidative stress in isolated CPCs. Here, we report that 24 h exposure to 5, 10, and 50 !g/mL of nanoceria did not a!ect cell growth and function in cardiac progenitor cells, while being able to protect CPCs from H2O2-induced cytotoxicity for at least 7 days, indicating that nanoceria in an e!ective antioxidant. Therefore, these "ndings con"rm the great potential of nanoceria for controlling ROS-induced cell damage

Tunable emission properties of CdSe/CdS quantum dots by Ce doping

A facile one-step hydrothermal synthesis to prepare cerium (Ce3+) ion doped CdSe/CdS core/shell quantum dots (QDs) is introduced. The effect of Ce3+ ion doping on structural and optical properties of the CdSe/CdS core/shell QDs is comprehensively investigated. With increasing Ce doping concentration, a linear increase in the lattice parameter is observed, suggesting the successful coupling of Ce3+ ions to the CdSe/CdS QDs. X-ray photoelectron spectroscopy reveals strong peaks of the Ce3+ state, indicating that Ce is initially present mainly in the Ce3+ ion state. In addition, red-shift over the range 538–569 nm is observed in the photoluminescence (PL) spectra of Ce3+ ion doped CdSe/CdS QDs. Results clearly indicates that the PL peak positions of the CdSe/CdS QDs could be controlled by the Ce content. This study highlights a new approach to tune the emission of the QDs

Degradation of orange II dye under dark ambient conditions by MeSrCuO (Me = Mg and Ce) metal oxides

This work investigates the catalytic performance and materials property of ternary metal oxides as Me0.25Sr0.25Cu0.5O (Me = Mg and Ce). The catalysts were tested for the heterogeneous degradation of orange II (OII) azo dye in aqueous solution in the dark at room temperature without any other reagents or energy/light irradiation. The MeSrCuO degraded more than 97% OII in the first 30 min, higher than that of binary metal oxides SrCuO (90.5%) or single metal oxides CeO2 (23.6%) and MgO (23.3%). The degradation pathway predominantly occurred by OII contacting the catalyst surface and resulting in the breakdown of azo bonds and the generation of electrons. Partial mineralization of OII dye occurred thus confirming the generation of radical species. Hence, electrons reacted with dissolved O2 in the OII aqueous solution, leading to the consecutive formation of reactive radical species (e.g., O2[rad]−, HO2[rad], H2O2, [rad]OH). Radical trapping experiment confirmed the presence of radical species. XPS analysis revealed part of Cu2+ underwent irreversible reduction after reaction due to the electron donation from OII with the accompanied increase in Cu+ species in the spent samples. Cycling tests confirmed the reduction of the catalytic activity, clearly indicating that Cu2+ was the active phase in MeSrCuO for the degradation of OII dye.</p

Combining top-down and bottom-up routes for fabrication of mesoporous titania films containing ceria nanoparticles for free radical scavenging

Nanocomposite thin films formed by amorphous mesoporous titania layers loaded with ceria nanoparticles have been obtained by combining bottom-up self-assembly synthesis of titania matrix with top-down hard X-ray lithography of nanocrystalline cerium oxide. At first the titania mesopores have been impregnated with the ceria precursor solution and then exposed to hard X-rays. The X-ray exposure of the films triggers the formation of crystalline cerium oxides within the pores inducing in-situ nanoparticles growing with average size of 4 nm. It has been observed that the type of coordinating agent in the solution plays a primary role in the formation of nanoparticles. Different patterns have been also produced through Deep X-ray Lithography by spatially controlling the nanoparticles growing on the micrometer scale. The radical scavenging role of the nanocomposite films have been tested using the UV photodegradation of rhodamine 6G as benchmark. After impregnation with a rhodamine 6G solution, samples with and without ceria have shown a remarkably different response upon exposure to UV light. The dye photodegradation on the surface of nanocomposite films appears strongly slow down because of the anti-oxidation effect of ceria nanoparticles