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In this paper, we examine controllability problems of evolution inclusions with nonlocal conditions. Using the set-valued and single-valued M?nch fixed-point theorem, we establish some sufficient conditions for the controllability...
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In this paper, we examine controllability problems of evolution inclusions with nonlocal conditions. Using the set-valued and single-valued M?nch fixed-point theorem, we establish some sufficient conditions for the controllability under convex and nonconvex orientor fields respectively. Our approach is different from all previous approaches; we do not assume that the evolution system generates a compact semigroup; so, our method is applicable to a wide class of (impulsive) control systems and evolution inclusions in Banach spaces.
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A finite volume, ocean circulation model was applied to the Discovery Islands region of British Columbia and used to simulate the three-dimensional velocity, temperature and salinity fields required by a companion biological trans...
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A finite volume, ocean circulation model was applied to the Discovery Islands region of British Columbia and used to simulate the three-dimensional velocity, temperature and salinity fields required by a companion biological transport model. The circulation model was initialized with a combination of climatological data and recent temperature and salinity observations, and forced with ⅰ) winds measured at seventeen weather stations, ⅱ) the discharges from twelve rivers, and ⅲ) five tidal constituents. A simulation for the period 1 April to 28 April 2010 was evaluated using simultaneous observations from three current meter moorings and the harmonics computed from historical measurements at twenty-four tide gauges. Though the model tidal elevations were shown to be in excellent agreement with the observations, profiles of model tidal speed versus depth generally did not capture observed vertical variations as well. Mean and low-pass filtered flow fields, though reasonably accurate near the surface, were also found to deteriorate farther down the water column. However, near-surface, model current harmonics were shown to be in reasonable agreement with those used to produce annual predictions at five sites in the Canadian Tide and Current Tables. Though the winds were not found to be a significant contributor to mean flow fields over the simulation period, tidal rectification was. Numerous residual and transient eddies that may lead to retentive regions in subsequent Lagrangian studies were predicted by the model. Future work and improvements to overcome model deficiencies are briefly outlined.
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Context . In recent years, coronal loops have been the focus of studies related to the damping of different magnetohydrodynamic (MHD) surface waves and their connection with coronal seismology and wave heating. For a better unders...
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Context . In recent years, coronal loops have been the focus of studies related to the damping of different magnetohydrodynamic (MHD) surface waves and their connection with coronal seismology and wave heating. For a better understanding of wave heating, we need to take into account the effects of different dissipation coefficients such as resistivity and viscosity, the importance of the loop physical characteristics, and the ways gravity can factor into the evolution of these phenomena. Aims . We aim to map the sites of energy dissipation from transverse waves in coronal loops in the presence and absence of gravitational stratification and to compare ideal, resistive, and viscous MHD. Methods . Using the PLUTO code, we performed 3D MHD simulations of kink waves in single, straight, density-enhanced coronal flux tubes of multiple temperatures. Results . We see the creation of spatially expanded Kelvin–Helmholtz eddies along the loop, which deform the initial monolithic loop profile. For the case of driven oscillations, the Kelvin–Helmholtz instability develops despite physical dissipation, unless very high values of shear viscosity are used. Energy dissipation gets its highest values near the apex, but is present all along the loop. We observe an increased efficiency of wave heating once the kinetic energy saturates at the later stages of the simulation and a turbulent density profile has developed. Conclusions . The inclusion of gravity greatly alters the dynamic evolution of our systems and should not be ignored in future studies. Stronger physical dissipation leads to stronger wave heating in our set-ups. Finally, once the kinetic energy of the oscillating loop starts saturating, all the excess input energy turns into internal energy, resulting in more efficient wave heating.
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The current study was undertaken to address the general question of whether there is an environmental advantage for renewable, starch-polyvinyl alcohol (PVOH) biopolymer blends over petrochemical polymers. This was addressed using...
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The current study was undertaken to address the general question of whether there is an environmental advantage for renewable, starch-polyvinyl alcohol (PVOH) biopolymer blends over petrochemical polymers. This was addressed using life cycle assessment (LCA) over a set of multiple case studies based on a consistent set of parameters and methodological background. A group of starch-PVOH blended biopolymers derived from different feedstocks (wheat, potato, maize) were compared with high density polyethylene (HDPE), low density polyethylene (LDPE) and expanded polystyrene (EPS) in a range of applications. The results suggest that a general environmental advantage does not exist for the starch-PVOH blended biopolymers over their petrochemical counterparts in all applications and, instead, a case-by-case approach is necessary to evaluate environmental pros and cons, based on specific comparisons. Overall, starch-PVOH biopolymers were found to offer environmentally superior options to LDPE in thermal packaging applications. However, this was not the case in other applications, where the outcome of comparisons between starch-PVOH biopolymers and HDPE/EPS varied according to various factors, including the specific end-of-life scenarios and the recycled content of the petrochemical polymers. A hierarchy of critical parameters for LCA-based decision-making concerning starch-PVOH biopolymers is suggested as a general outcome of this research.
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In this study, pre-cracked cubic specimens of concrete materials were especially prepared in a concrete laboratory to study the breaking process of brittle solids. Then, the linear elastic fracture mechanics concept of the stress ...
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In this study, pre-cracked cubic specimens of concrete materials were especially prepared in a concrete laboratory to study the breaking process of brittle solids. Then, the linear elastic fracture mechanics concept of the stress intensity factor and the experimental methods were used to investigate the failure mechanism of pre-cracked concrete specimens under compression. The crack propagation mechanism and the ultimate strengths of these specimens were obtained in the laboratory. Several numerical analyses were also carried out on the pre-cracked specimens, using the finite element method and ABAQUS software package. The damage location and convergence diagram of the differential evolutionary algorithm under mode I, II, III or IV loading conditions were investigated for the cubic pre-cracked concrete specimens containing a single center crack with different inclination angles. The crack propagation mechanisms obtained numerically were compared with the corresponding experimental ones proving the proposed method's feasibility.
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The corrosion behaviour of magnesia-chromite refractory by an alumina-rich (15-20 wt. percent) stainless steelmaking slag is investigated by rotating finger tests in a vacuum induction furnace. The influence on the refractory wear...
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The corrosion behaviour of magnesia-chromite refractory by an alumina-rich (15-20 wt. percent) stainless steelmaking slag is investigated by rotating finger tests in a vacuum induction furnace. The influence on the refractory wear, of the process temperature, corrosion time and, in particular, the high Al_2O_3 content in the slag, is discussed. Two distinct mechanisms cause primary chromite degradation: FeO_x and Cr_2O_3 decomposition because of low oxygen potentials and dissolution by infiltrated slag due to the high Al_2O_3 slag content. Upon decomposition, small metallic particles and pores are homogeneously generated inside the primary chromite. At the refractory/slag interface, a relatively continuous solid (Mg,Mn)[Al,Cr]_2O_4 spinel layer is formed. Its density and stability decreases with higher temperatures and more turbulent conditions. The spinel formation arises through heterogeneous in situ precipitation from a slag rich in spinel forming compounds. Higher Al_2O_3 levels in the slag promote the spinel layer formation, which may limit slag infiltration. Finally, it is shown that the present experimental procedure is an excellent tool to simulate refractory wear in industrial processes, diminishing the risks associated with plant trials.
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Porcine enteric calicivirus (PEC/Cowden) causes diarrhea in pigs, grows in cell culture, and is morphologically and genetically similar to the Sapporo-like human caliciviruses. Genetic analysis revealed that the tissue culture-ada...
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Porcine enteric calicivirus (PEC/Cowden) causes diarrhea in pigs, grows in cell culture, and is morphologically and genetically similar to the Sapporo-like human caliciviruses. Genetic analysis revealed that the tissue culture-adapted (TC) Cowden PEC has one distant and three clustered amino acid substitutions in the capsid region and 2 amino acid changes in the RNA polymerase region compared to wild-type (WT) PEC (M. Guo, K.-O. Chang, M. E. Hardy, Q. Zhang, A. V. Parwani, and L. J. Saif, J. Virol. 73:9625–9631, 1999). In this study, the TC PEC, passaged in a porcine kidney cell line, and the WT PEC, passaged in gnotobiotic (Gn) pigs, were used to orally inoculate 13 4- to 6-day-old Gn pigs. No diarrhea developed in the TC-PEC-exposed pigs, whereas moderate diarrhea developed in the WT-PEC orally inoculated pigs, persisting for 2 to 5 days. Fecal virus shedding persisting for at least 7 days was detected by both reverse transcription (RT)-PCR and antigen-enzyme-linked immunosorbent assay (antigen-ELISA) in both TC-PEC and WT-PEC orally inoculated pigs but not in mock-inoculated pigs. The PEC particles were detected by immunoelectron microscopy (IEM) in intestinal contents from all the WT-PEC-inoculated pigs, but not from the TC-PEC-inoculated pigs. Mild (duodenum and jejunum) or no (ileum) villous atrophy was observed in histologic sections of the small intestines of TC-PEC-inoculated pigs, whereas WT PEC caused mild to severe (duodenum and jejunum) villous atrophy and fusion. Scanning electron microscopy confirmed mild shortening and blunting of villi in the duodenum and jejunum of the TC-PEC-inoculated pigs, in contrast to moderate to severe villous shortening and blunting in the duodenum and jejunum of WT-PEC-inoculated pigs. Higher numbers of PEC antigen-positive villous enterocytes were detected by immunofluorescent (IF) staining in the proximal small intestine of the WT-PEC-inoculated pigs, in contrast to low numbers of PEC antigen-positive enterocytes in only one of four TC-PEC-inoculated pigs. No PEC antigen-positive cells were observed in the colon or extraintestinal tissues of all inoculated pigs or in the small intestine of one mock-inoculated pig. Thus, the TC PEC was at least partially attenuated (no diarrhea, mild lesions) after serial passage in cell culture. In further experiments, three 4- to 6-day-old Gn pigs were intravenously (i.v.) inoculated with WT PEC, and all pigs developed diarrhea and villous atrophy in the small intestines resembling that observed in the orally inoculated pigs. Fecal viral shedding persisting for 8 days was detected by both RT-PCR and antigen-ELISA, and PEC was detected by IEM in feces or intestinal contents. The PEC RNA and antigens (at low titers) were detected in acute-phase sera from all the WT-PEC i.v.-inoculated pigs and also from seven of nine of the WT-PEC orally inoculated pigs. Oral or i.v. inoculation of four additional pigs with the PEC-positive acute-phase sera induced diarrhea, small intestinal lesions, PEC shedding in feces, and seroconversion to PEC, confirming the occurrence of viremia during PEC infection, with infectious PEC present in acute-phase sera. No diarrhea, histopathologic changes, or IF staining in the small intestine or fecal or serum detection of PEC was evident in two pigs i.v. mock-inoculated or a pig inoculated i.v. with inactivated WT PEC. To our knowledge, this is the first report of an attenuated enteric calicivirus, the induction of diarrhea, and intestinal lesions in Gn pigs caused by i.v. inoculation of WT PEC and the presence of viremia following PEC infection.
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A life cycle assessment (LCA) approach was used to explore fossil energy profiles of current and future scenarios for the production of the biopolymer polyhydroxybutyrate-valerate (PHBV). The study was based on primary data collec...
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A life cycle assessment (LCA) approach was used to explore fossil energy profiles of current and future scenarios for the production of the biopolymer polyhydroxybutyrate-valerate (PHBV). The study was based on primary data collected from industry sources and laboratory research, focused on evaluating the long-term quantitative and qualitative depletion of fossil fuel resources associated with the production of PHBV. The results show that corn farming and corn-glucose production were the dominant contributors to fossil fuel depletion (expressed in MJ surplus energy) over the life cycle of PHBV produced under the current production scale. However, PHBV is presently undergoing substantial development in comparison with the well-developed petrochemical alternatives. The results of forward-looking scenarios under an expanded production scale indicate that the use of renewable resources for process energy requirements for PHBV and glucose production coupled with improved C-utilization efficiency have the potential to reduce fossil fuel depletion by over 50% compared with its current production scale. The use of appropriate lignocellulosic feedstocks and processing technology for glucose production offers potential for further improvement. These results with PHBV support the view that it will be possible with future developments to move to biopolymer production systems that are largely independent of fossil fuels.
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AbstractBackground: Sertoli cells (SCs) have been described as the ‘nurse cells’ of the testis whose primary function is to provide essential growth factors and create an appropriate environment for development of other cells [for...
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AbstractBackground: Sertoli cells (SCs) have been described as the ‘nurse cells’ of the testis whose primary function is to provide essential growth factors and create an appropriate environment for development of other cells [for example, germinal and nerve stem cells (NSCs), used here]. However, the greatest challenge at present is that it is difficult to obtain sufficient SCs of normal physiological function for cell transplantation and biological medicine, largely due to traditional static culture parameter difficult to be monitored and scaled up.
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The corrosion behaviour of a pitch-bonded magnesia-carbon refractory by an Al_2O_3 rich (approx 15 wt. percent) stainless steelmaking slag was investigated by rotating ringer tests in a vacuum induction furnace at high temperature...
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The corrosion behaviour of a pitch-bonded magnesia-carbon refractory by an Al_2O_3 rich (approx 15 wt. percent) stainless steelmaking slag was investigated by rotating ringer tests in a vacuum induction furnace at high temperature (>1650 deg C) and low oxygen partial pressure (1.5-4.3 x 10~(-10) atm). This study confirms the poor slagline behaviour of MgO-C bricks industrially observed in VOD ladles. Higher temperatures and longer exposure times lead to more severe slag infiltration and direct MgO dissolution. The intrinsic MgO-C reaction is the major decarburisation mechanism, while extrinsic decarburisation by oxygen from the atmosphere and/or reducible slag components (CrO_x, FeO_x) was limited. Three kinds of metallic particles with different size, shape, location, composition and origin were observed in the refractory specimens. Concurrently, the thermodynamic conditions for the formation of a protective Mg(Al,Cr)_2O_4 spinel layer at the slag/refractory interface are investigated. The industrial relevance of this spinel layer formation is discussed with respect to the chosen Al_2O_3 level. Guidelines are proposed to minimise MgO refractory dissolution in VOD slaglines.
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