Dynamically crosslinked thermoplastic elastomer nanocomposites were synthesized as modifier for the bitumen binder-based asphalts. Linear low-density polyethylene (LLDPE) and styrene-butadiene rubber (SBR), with the ratio of 80/20, bitumen, and organically modified clay (OC) were all melt mixed in the presence of the sulfur curing system. The proposed mixing was carried out in an internal mixer at 160 °C with a rotor speed of 120 rpm. To enhance the molecular interactions between the polymer phases and the clay silicate layers, maleic anhydride-grafted LLDPE (PE-g-MA) with the maleiation degree of 50% was also incorporated into the mixture. Observation of the composite samples, using the scanning electron microscopy (SEM), revealed the matrix dispersed type of morphology for all dynamically vulcanized samples. X-ray diffraction (XRD) and transmission electron microscopy (TEM) examinations evidenced the exfoliation of the clay silicate layers with good dispersion. Rheomechanical spectrometry (RMS) was performed on the prepared nanocomposites. All dynamically vulcanized nanocomposites comprising 2.5% of OC exhibited shear-thinning behavior and non-terminal characteristics with a low frequency range. These indicate the formation of three-dimensional physical networks by the clay nanolayers throughout the LLDPE matrix. The presence of the bitumen in the composition of the prepared nanocomposites improved the flowability of the samples. This is a promising feature of the prepared nanocomposites to be used as an elastic and resistant modifier in the composition of the bitumen-based asphalts.
The thermomechanical behavior of micro/nano-alumina (Al2O3) ceramics reinforced with 1-5 wt.% of acid-treated oil fly ash (OFA) was investigated. Composites were sintered using spark plasma sintering (SPS) technique at a temperature of 1400°C by applying a constant uniaxial pressure of 50 MPa. It was evaluated that the fracture toughness of micro- and nanosized composites improved in contrast with the monolithic alumina. Highest fracture toughness value of 4.85 MPam1/2 was measured for the nanosized composite reinforced with 5 wt.% OFA. The thermal conductivity of the composites (nano-/microsized) decreased with the increase in temperature. However, the addition of OFA (1-5 wt.%) in nanosized alumina enhanced the thermal conductivity at an evaluated temperature. Furthermore, a minimum thermal expansion value of 6.17 ppm*K−1 was measured for nanosized Al2O3/5 wt.% OFA composite. Microstructural characterization of Al2O3-OFA composites was done by x-ray diffraction and Raman spectroscopy. Oil fly ash particles were seen to be well dispersed within the alumina matrix. Moreover, the comparative analysis of the nano-/microsized Al2O3/OFA composites shows that the mechanical and thermal properties were improved in nanosized alumina composites. 相似文献
Matrix-assisted laser desorption/ionization (MALDI) time-of-flight (TOF) mass spectrometry (MS) has been used to identify
eight triacylglycerols (TAG) in Vernonia galamensis oil (VO). The TAG include trivernolin, divernoloylstearoylglycerol, divernoloyloleoylglycerol, vernoloyllinoleoylstearoylglycerol,
vernoloyllinoleoyloleoylglycerol, and vernoloyldilinoleoylglycerol. Samples for the MALDI/TOF/MS analysis were prepared with
alpha-cyano-4-hydroxycinnamic acid (matrix) in an acetonitrile/tetrahydrofuran solvent system. A mol ratio of matrix/VO (44:1)
gave reproducible composite spectra, resulting in resolutions greater than 8,000 and signal-to-noise ratios of above 1000
for the most abundant molecular species. 1,3-Dioleoyl-2-stearoylglycerol and 1,2-dioleoyl-3-palmitoylglycerol were used as
calibration standards. 相似文献
Two key decisions in designing cellular manufacturing systems are cell formation and layout design problems. In the cell formation problem, machine groups and part families are determined while in the facility layout problem the location of each machine in each cell (intra-cell layout) and the location of each cell (inter-cell layout) are decided. Owing to the fact that there are interactions between two problems, cell formation and layout design problem must be tackled concurrently to design a productive manufacturing system. In this research, two problems are investigated concurrently. Some important and realistic factors such as inter-cell layout, intra-cell layout, operations sequence, part demands, batch size, number of cells, cell size, and variable process routings are incorporated in the problem. The problem is formulated as a mathematical model. Three different methods are described to solve the problem: multi-objective scatter search (MOSS), non-dominated genetic algorithm (NSGA-II), and the ε-constraint method. The methods are employed to solve nine problems generated and adopted from the literature. Sensitivity analysis is accomplished on the parameters of the problem to investigate the effects of them on objective function values. The results show that the proposed MOSS algorithm performs better than NSGA-II and produces better solutions in comparison to multi-stage approaches. 相似文献
A green and efficient dispersive liquid-liquid microextraction method based on a new deep eutectic solvent has been developed for the preconcentration and extraction of cobalt and nickel ions. The deep eutectic solvent is formed by mixing choline chloride (hydrogen bond acceptor) and 4-aminophenol (hydrogen bond donor). Then, it is used as a chelating agent as well as extraction solvent. Under the optimum experimental conditions, the linear ranges for Ni(II) and Co(II) were 0.80–50 and 0.50–50 µgL?1, respectively, by flame atomic absorption spectrometry. The obtained detection limits were 0.30 and 0.22 µg L?1 for Ni(II) and Co(II), respectively. 相似文献
Structural and compositional modification of InSb(0 0 1) single crystal surfaces induced by oblique incidence 2-5 keV Ar and Xe ion irradiation have been investigated by means of scanning tunneling and atomic force microscopies, and time-of-flight mass spectroscopy of secondary ion emission. In general, ion-induced patterns (networks of nanowires, or ripples) are angle of incidence- and fluence-dependent. Temperature dependences (from 300 to 600 K) of the RMS roughness and of the ripple wavelength have been determined for the samples bombarded with various fluences. Secondary ion emission from an InSb(0 0 1) surface exposed to 4.5 keV Ar+ ions has been investigated with a linear TOF spectrometer working in a static mode. Mass spectra of the sputtered In+, Sb+ and In2+ secondary ions have been measured both for the non-bombarded (0 0 1) surface and for the surface previously exposed to a fluence of 1016 ions/cm2. In+ and In2+ intensities for the irradiated sample are much higher in comparison to the non-bombarded one, whereas Sb+ ions show a reversed tendency. This behavior suggests a significant In-enrichment at the InSb(0 0 1) surface caused by the ion bombardment. 相似文献
This paper presents a new and innovative optimization technique, which uses cellular automata for solving multi-objective optimization problems. Due to its ability in simulating the local information while taking neighboring effects into account, the cellular automata technique is a powerful tool for optimization. The fuel-loading pattern in nuclear reactor cores is a major optimization problem. Due to the immensity of the search space in fuel management optimization problems, finding the optimum solution requires a huge amount of calculations in the classical method. The cellular automata models, based on local information, can reduce the computations significantly. In this study, reducing the power peaking factor, while increasing the initial excess reactivity inside the reactor core of VVER-1000, which are two apparently contradictory objectives, are considered as the objective functions. The result is an optimum configuration, which is in agreement with the pattern proposed by the designer. In order to gain confidence in the reliability of this method, the aforementioned problem was also solved using neural network and simulated annealing, and the results and procedures were compared. 相似文献
The coatings of optical fibers are generally characterized by a multi-layer coating structure. In this work, the mathematical modeling of two immiscible non-Newtonian fluids for optical fiber coating inside a straight annular die is developed in the form of a nonlinear differential equation with nonhomogeneous boundary conditions. Two non-Newtonian fluids, namely power law and Phan-Thien–Tanner fluids, are used in the primary and secondary coating dies, respectively. An exact solution is obtained for velocity fields and temperature distributions for the primary and secondary coating resins. The thickness of coated fiber optics is also calculated for both layers. The effect of different emerging parameters on the solution is discussed and sketched. 相似文献
Taxonomy of the genus Berberis is quite complex, due to overlapping morphological characters, making it very difficult to differentiate the species within the genus. In order to resolve this taxonomic complexity, the foliar anatomy of 10 Berberis L. species was carried out, for the first time from Pakistan, using light microscopy (LM). Significant variation in terms of epidermal cells shape, size, cell wall pattern, and stomata type was observed. B. baluchistanica has the largest epidermal cells, Adaxial: length = 45–(53.9 ± 3.6)–62.5 μm; and width = 22.5–(26.3 ± 1.3)–30 μm; Abaxial: length = 37.5–(43.25 ± 2.5)–50 μm; and width = 20–(22.6 ± 0.8)–25. The highest number of stomata was observed in B. glaucocarpa as 62 on the abaxial surface while the lowest number of stomata was recorded in B. baluchistanica as 8 on the adaxial surface. Of 10 investigated species, 6 possess anomocytic type stomata, while 2 species that is, B. aitchisonii and B. parkeriana have both anomocytic and anisocytic stomata while B. baluchistanica and B. calliobotrys have only paracytic type stomata. The highest number of cells per unit area was present on the adaxial surface of B. calliobotrys ranging from 245–(252.4)–260 followed by B. parkeriana with 209–(227.8)–250 on the abaxial surface. Stomatal index (SI) also varied considerably and was the lowest (2.6) percentage in B. baluchistanica and highest (31.9) percentage in B. kunawurensis. A taxonomic key based on micro‐morphological characters is provided for species identification. 相似文献