Physical,antimicrobial and antibiofilm properties of Zataria multiflora Boiss essential oil nanoemulsion

It was evaluated physical, antibacterial and antibiofilm properties of Zataria multiflora Boiss essential oil (ZEO) and its nanoemulsion. Long‐term stability of nanoemulsion prepared by emulsion phase inversion was satisfying based on low narrow size distribution (polydispersity index ?0.2) and low droplet size (200 nm) over 21 days of storage. Nanoemulsion showed lower minimum inhibitory concentration (MIC) on Listeria monocytogenes (2500 µg mL^?1) than Salmonella Typhimurium (5000 µg mL^?1). Killing kinetics study revealed that nanoemulsion was more effective in inhibiting the growth of bacteria in milk than culture media. Both bacteriostatic and bactericidal effects were observed depending on the type of bacteria, nanoemulsion concentration and the time of exposure. Nanoemulsion at 4×MIC concentration reduced 64% and 75% of one‐day‐old biofilm of L. monocytogenes and S. Typhimurium, respectively. In conclusion, nanoemulsion revealed antimicrobial activity, but converting the ZEO to nanoemulsion did not improve its antibacterial activity; however, antibiofilm properties were enhanced.     

Numerical investigation of structural crash response of thin-walled structures on soft soil

Accident statistics show that although the certification of aircraft structures is based on crash scenarios on hard or rigid surfaces, in reality most of the crash cases occur on soft soil or water. Therefore a structure which is designed for hard surfaces may not be safe enough for a possible crash scenario on water or soft soil. Finite element method (FEM) has been used in several numerical investigations and promising results were obtained. However, since soil is a granular medium this work aims at numerical modeling of the experimentally observed soil behavior using particle-based numerical technique. In this work numerical simulations of the crash tests on idealized cones and hemispheres were used to validate the models and compare FEM-based models with particle-based models. The results of numerical simulations were compared with quasi-static and dynamic test results conducted on coarse sand sample at the Deutsches Zentrum fur Luft- und Raumfahrt e.V (DLR). After obtaining a stable and accurate particle-based numerical model for the soft soil the crash performance of deformable metallic energy absorbers on soft soil ground was investigated and compared with test data and numerical investigations of rigid ground impacts.     

Modeling pressure relationships of inspired air into the human lung bifurcations through simulations

Applied pressure on human lung wall has great importance on setting up protective ventilatory strategies, therefore, estimating pressure relationships in terms of specific parameters would provide invaluable information specifically during mechanical ventilation (MV). A three-dimensional model from a healthy human lung MRI is analyzed by computational fluid dynamic (CFD), and results for pressure are curve fitted to estimate relationships that associate pressure to breathing time, cross section and generation numbers of intended locations. Among all possible functions, it is observed that exponential and polynomial pressure functions present most accurate results for normal breathing (NB) and MV, respectively. For validation, pressure-location curves from CFD and results from this study are compared and good correlations are found. Also, estimated pressure values are used to calculate pressure drop and airway resistance to the induced air into the lung bifurcations. It is concluded that maximum pressure drop appeared in generation number 2 and medium sized airways show higher resistance to air flow and that resistance decreased as cross sectional area increased through the model. Results from this study are in good agreement with previous studies and provide potentials for further studies on influence of air pressure on human lung tissue and reducing lung injuries during MV.     

Effect of carrier types and compositions on the production yield,microstructure and physical characteristics of spray dried sour cherry juice concentrate

In this study, the effect of different carriers including maltodextrin (MD), gum arabic (GA) and whey protein concentrate (WPC) and their combination on the production yield, moisture content, bulk and tapped density, solubility, wettability, flowability indexes (Hausner ratio, compressibility, angle of repose), hygroscopicity and deliquescence process, color index and microstructure of spray dried sour cherry juice concentrate was investigated. The results showed increased powder production yield with a mixture of MD and GA (40:10 weight ratio). Use of 5% WPC in combination with the GA and MD increased powder production yield from 45.66 to 55.66% and 42.23 to 52.86%, respectively. Bulk density, tapped density, solubility and wettability significantly decreased with increasing concentration of WPC. Also, the use of 30% WPC in combination with the MD or GA increased particle size substantially. The surface morphology of the particles (with a smooth, shrunk and dented surfaces) was affected by feed composition.     

Three-stage hybrid osmotic–intermittent microwave–convective drying of apple at low temperature and short time

ABSTRACT

In recent years, intermittent microwave coupled with hot air-drying has been used increasingly, thanks to considerable improvements observed in drying properties. The aim of this study was to investigate the effect of process of drying apple pretreated osmotically with sucrose solution at five concentrations of 0 (control), 10, 30, 50, and 70% (w/w), using intermittent microwave at four power levels of 0 (control), 360, 600, and 900?W, four pulse ratios of 1, 2, 3, and 4, and convective hot air (40°C) on drying kinetics, effective moisture diffusion coefficient, shrinkage, bulk density, rehydration ratio, and energy consumption. Results showed that the three-stage hybrid osmotic–intermittent microwave–convective drying of apple at low temperature yielded higher drying rates (with 41.5% decrease in drying time) and improved quality of final product. The effective moisture diffusion coefficient increased with an increase in power, pulse ratio, and the concentration of osmotic solution. Furthermore, shrinkage, bulk density, and energy consumption of the samples decreased with an increase in power, pulse ratio, and the concentration of osmotic solution. In summary, the use of intermittent microwave coupled with forced convection of hot air (at low temperature) in drying of apple pretreated by sucrose osmotic solution led to products with improved properties in terms of both quality and quantity.     

A new exposure route to trace elements in indoor particulate matter

Concentrations and emission rates of sixteen trace elements in emitted PM during heating soybean oil using three types of pans, including Teflon, granitium, and cast-iron, were investigated. Statistically significant decreases in Mn and Co emission rates were observed when the oil was heated in the cast-iron pan compared to Teflon and granitium pans. Among the released trace elements, Ni, Ba, Zn, and Cr had more contribution to the emission rate. The concentrations of Fe in the emitted PM₁ were found to be higher when cast-iron pan (8.49 ± 3.35 µg/m³) was utilized compared to Teflon (8.05 ± 2.27 µg/m³) and granitium (7.45 ± 1.38 µg/m³). However, these increases were statistically insignificant. The results of our study support the hypothesis that the trace elements translocate from cooking pans into the heated oil and subsequently to the particulate phase. This translocation creates a new inhalation exposure route to trace elements in indoor environments.     

Co-precipitated ZnAl2O4 spinel precursor as potential sintering aid for pure alumina system

Ultra-fine ZnAl₂O₄ spinel hydrogel precursor synthesized from mixed salt solutions of Zn²⁺ and Al³⁺ ions using ammonium hydroxide–hexamethylenetetramine as basic media for co-precipitation was used as bonding material and sintering aid for pure alumina system. The hydrogel powder exhibited some well-defined ZnAl₂O₄ spinel phases at 800 °C. Alumina compacts were fabricated by incorporating small proportions of the precursor in alumina powder and firing at different temperatures (1350–1500 °C). The degree of densification was studied by measurement of fired shrinkage, apparent porosity, bulk density and cold crushing strength. Phase compositions and microstructural features of sintered samples were evaluated by XRD and SEM respectively. Addition of 0.2% hydrogel powder to alumina exhibited remarkable influence on development of high mechanical strength. The in situ formed ZnAl₂O₄ spinel dopant acted as a grain growth inhibitor in the alumina system.     

Quality of service aware traffic scheduling in wireless smart grid communication

The next generation electrical power grid, known as smart grid (SG), requires a communication infrastructure to gather generated data by smart sensors and household appliances. Depending on the quality of service (QoS) requirements, this data is classified into event-driven (ED) and fixed-scheduling (FS) traffics and is buffered in separated queues in smart meters. Due to the operational importance of ED traffic, it is time sensitive in which the packets should be transmitted within a given maximum latency. In this paper, considering QoS requirements of ED and FS traffics, we propose a two-stage wireless SG traffic scheduling model, which results in developing a SG traffic scheduling algorithm. In the first stage, delay requirements of ED traffic is satisfied by allocating the SG bandwidth to ED queues in smart meters. Then, in the second stage, the SG rest bandwidth is going to the FS traffic in smart meters considering maximizing a weighted utility measure. Numerical results demonstrate the effectiveness of the proposed model in terms of satisfying latency requirement and efficient bandwidth allocation.     

Comparison of several methods for obtaining hydrate formation pressure

In petroleum engineering hydrate is referred to as crystalline and snow like compounds Which consists of the capture of gaseous molecules among water molecules. The primary requirement for the prevention of hydrate is to recognize the conditions for its formation. Hydrate formation conditions include the presence of water, small gas molecules and the appropriate conditions of temperature and pressure. Several models have been proposed to determine the hydration pressure and temperature. Van der waals-platteeuw is a model base on statistical thermodynamics. In this model, the determinant is the fugacity of the gas phase. In this paper, the fugacity is obtained with different equations of state and replaced by the pattern provided by Parish and Prasnitz, to obtain the pressure and temperature of hydrate formation. In the end, results are compared with laboratory data and results from the CSMHyd Software and the experimental data to Check the accuracy of the model.     

Modeling and Transport Analysis of Silver Extraction in Porous Membrane Extractors by Computational Methods

A comprehensive two-dimensional mathematical model was developed for the transport of $ {\text{Ag(CN)}}_{ 2}^{ - } $ ions through porous membrane extractors. Extraction of $ {\text{Ag(CN)}}_{ 2}^{ - } $ with n-heptane solution of N,N-bis(2-ethyl hexyl) guanidine as extractant (LIX79) was investigated theoretically. Simulations were done using computational fluid dynamics of momentum and mass transfer in all subdomains of a hollow-fiber membrane extractor by COMSOL Multiphysics software. The latter uses finite element method for numerical simulations. Parabolic velocity profile was used for the aqueous feed in the tube side and the solvent flow in the shell side that was characterized by Happel’s equation. The distribution of concentration was obtained for the solute in the membrane module. Simulation results indicated that increasing feed flow rate reduces the extraction efficiency of silver from aqueous phase to organic phase. Dimensionless concentration distribution (C/C₀) of silver ions in the tube side of membrane extractor in axial and radial direction shows that it moves to the membrane due to the concentration difference, and then it is swept by the moving extractants in the shell.