In this paper, we analyze a linearized model for incompressible transversely isotropic dispersive fiber-reinforced materials in which both the elastic and dispersive properties depend on the direction of the fibers. We investigate the motions in bodies made of these materials that are subjected to prescribed shear or normal action on part of the rigid boundaries. In the case where the motion is induced by shear stresses acting at the boundary, we provide the analytical solution for the displacement field from which we derive the components of the stress tensor. In the case where the motion is due to the action of normal stresses at the boundary, the initial and boundary value problem is solved using a projection algorithm based on spectral methods. In both cases, we quantify how anisotropic dispersion and material stiffness affect the displacement field.
Malaxation is essential in the extra virgin olive oil (EVOO) processing to induce several phenomena, but algorithms based on kinetic approach for predicting the effect of malaxation operating conditions on both oil process yield and EVOO quality are lacking. The kinetics phenolic compounds (PC) and positive volatile organic compounds (i.e., (E)-2-hexenal) were studied in lab scale at different time-temperature malaxation treatments under low oxidative operating conditions. The kinetics were also linked with the literature kinetics data of both negative volatile organic compounds (i.e., 2+3-methylbutanal) formation and oil process yield indices. A first computer program (MalaxAction 2.1) was set up to design malaxation by planning time-temperature conditions to maximize or select combined levels of (E)-2-hexenal content, PC total content and apparent extraction yield, without exceeding threshold value of 2+3-methylbutanal contents. A second computer program (MalaxAction 2.2) was set up to control malaxation by determining effects of both every time-temperature condition and unsteady heat transfer on the above EVOO quality characteristics and oil process yield. An opposite effect on increase of both phenolic compounds and pleasant volatile organic compounds was predicted without oil sensory defect by the MalaxAction 2.1. A maximization of extraction yield can be also consistently reached increasing PC total content, but not increasing the (E)-2-hexenal content. However, the designed time-temperature conditions have less applicability if the heat transfer resistance of malaxers are not considered. MalaxAction 2.2 program was able to both check feasibility of actual malaxation temperature profile and, if necessary, adjust it to reach the designed goal.
Accurate yet computationally efficient treatment of combustion chemistry remains a major challenge in largescale reactive-flow simulations, particularly in industrial applications where long transient calculations and high spatial resolution are required. Analytically Reduced Chemistry (ARC) addresses this challenge through a multi-step reduction strategy combining skeletal reduction, species/reaction lumping, and Quasi-Steady-State Assumption (QSSA) in order to reduce both the number of transported species and the stiffness of the chem ical source-term system while retaining kinetic fidelity. This study presents the development, validation, and first integration of an ARC mechanism within the ANSYS (R) Fluent commercial solver, which is widely used as a Large-Eddy Simulation (LES) reference tool for gas turbine combustor design and analysis. The mechanism is specifically developed for industrial natural-gas combustion applications involving elevated-pressure opera tion, hydrogen enrichment, and diluted-reactant conditions. The reduction workflow, supported by intermediate validation in Cantera, is outlined, followed by the implementation of the ARC formulation within Fluent's species-transport framework. ARC accuracy is assessed against experimental laboratory flame data, while stiffness and computational cost are evaluated against skeletal mechanisms on an industrial test rig. Results show that ARC maintains strong predictive capability while markedly reducing the dimensionality and stiffness of the trans ported chemistry system, yielding substantial gains in numerical robustness and computational efficiency that make it suitable for high-fidelity industrial reactive LES workflows.
Leafy greens are susceptible to contamination by human pathogens, and because ready-to-eat salads cannot undergo thermal decontamination, even initial contamination poses a food safety risk. To understand early bacterial colonization, we combined high-resolution fluorescence microscopy with Generalized Additive Models (GAMs) to investigate development of Escherichia coli micro-colonies on the leaves of romaine lettuce (Lactuca sativa L. var. longifolia) and wild lettuce (Lactuca serriola L.). Green Fluorescent Protein labelled bacteria were used as experimental tracers to visualize colonization dynamics under controlled conditions. Bacterial proliferation was quantified through fluorescence area, representing spatial expansion, and fluorescence intensity, reflecting aggregation; their combined metric provided a reliable proxy for micro-colony development. Over the 24 h incubation period, romaine lettuce consistently supported higher colonization than wild lettuce, reflecting differences in leaf surface micro-morphology. Maximum surface roughness emerged as a structural factor associated with bacterial proliferation. GAMs captured nonlinear growth patterns and species-specific responses, with romaine models explaining up to 91% of the observed variance. Comparison with Colony Forming Units (CFU) counts showed that fluorescence imaging resolved early spatial aggregation and colony expansion, whereas CFU measurements assessed culturability but lost spatial information due to tissue homogenization. Although fluorescence imaging based on genetically labelled bacteria is not directly applicable to post-harvest monitoring, it provides a platform for establishing predictive relationships between leaf surface traits and microbial growth. GAMs represent the transferable outcome of the study, enabling quantitative evaluation of temporal and morphological predictors of colonization dynamics and supporting approaches for improving microbiological safety in fresh-cut salad production systems.
Urban roadside environments are characterized by altered microclimate and soil conditions that impose recurrent drought stress on trees, affecting their physiological performance and adaptive capacity. Understanding species-specific physiological and structural responses to drought stress is crucial for selecting tree species that are suitable for urban environments. In the present study, we investigated the species-specific and temporal (monthly) patterns of the in situ leaf physiological status and structural traits of two riparian tree species, Quercus robur L. and Carpinus betulus L., cultivated as urban roadside trees in Novi Sad, Serbia, throughout the growing season (from June to September). This was achieved by assessing leaf gas exchange and rapid light curves of chlorophyll a fluorescence together with leaf structural traits. Under drought stress, Q. robur exhibited sustained photosynthetic activity and transpiration rates due to reduced stomatal sensitivity, indicative of a more anisohydric behavior with respect to its water relations strategy. In contrast, C. betulus exhibited tighter stomatal regulation and showed lower assimilation rates accompanied by reduced cooling capacity, indicating stricter, more conservative water-balance management indicative of isohydric species. Fluorescence indices revealed contrasting behavior: C. betulus showed enhanced NPQ values accompanied by a decline in photosynthetic efficiency, while Q. robur exhibited lower NPQ, suggesting better maintenance of photosynthetic performance and electron transport in PSII under the observed drought stress. These patterns were further supported by higher stomatal density combined with smaller stomatal size, indicating faster stomatal response rates in C. betulus compared to Q. robur. Overall, these results suggest that C. betulus is a more promising riparian tree species for urban landscapes, particularly under drought-prone conditions and predicted climate changes, in comparison to Q. robur.
