Numerical simulation of transient heat transfer for tomato paste in semi rigid aluminum container

In this study, numerical model of heat transfer for tomato paste in semi-rigid aluminum container was developed by Fluent software 6.3.26. Grid independence was recognized. The impact of head space (air and water -vapor) and buoyancy force on heat transfer were investigated. Simulation results showed slowest heating zone (SHZ) located in (?11.676?<?X?<??10.738, 0.183?<?Y?<?1.269 and 4.417?<?Z?<?5.560) for model with air head space and in (?11.166?<?X?<??11.370, 0.762?<?Y?<?1.21 and 5.480?<?Z?<?5.506) for model with water–vapor head space in Cartesian system coordinate. A thermocouple was connected to container at (0, 0, 10 cartesian system coordinate) to get experimental data during process. Comparing temperatures of experimental model and predicted model (with head space) illustrated no significant difference (p?<?0.05).     

Process Optimization,Physical Properties,and Environmental Stability of an α-Tocopherol Nanocapsule Preparation Using Complex Coacervation Method and Full Factorial Design

α-Tocopherol (α-Toc) has valuable biological activity, but its activity is limited when exposed to environmental factors. Nanocapsules can be used to overcome this problem. Using nanocapsules in the range of 100–200 nm is more beneficial. A 2⁴ full factorial design was carried out to optimize the size of nanocapsules using the complex coacervation method. The four factors were the amount of the wall material, the ratio of core material to wall material, the pH of the solution, and the speed of the homogenizer. The smallest nanocapsules (176 nm) were obtained at a wall content (gelatine and pectin) of 0.8 mg, a percentage of core material (α-Toc) to wall material of 20%, a pH = 4.5, and a homogenizer speed of 12,000 rpm. The encapsulation efficiency was 90.6 ± 1.1%, and the encapsulation yield was 83.4 ± 1.6%. Assessment of the stability of α-Toc after 1 month showed that encapsulation could improve its stability in the presence of three influential factors: humidity, light, and temperature.     

Development of ocular drug delivery systems using molecularly imprinted soft contact lenses

Recently, significant advances have been made in order to optimize drug delivery to ocular tissues. The main problems in ocular drug delivery are poor bioavailability and uncontrollable drug delivery of conventional ophthalmic preparations (e.g. eye drops). Hydrogels have been investigated since 1965 as new ocular drug delivery systems. Increase of hydrogel loading capacity, optimization of drug residence time on the ocular surface and biocompatibility with the eye tissue has been the main focus of previous studies. Molecular imprinting technology provided the opportunity to fulfill the above-mentioned objectives. Molecularly imprinted soft contact lenses (SCLs) have high potentials as novel drug delivery systems for the treatment of eye disorders. This technique is used for the preparation of polymers with specific binding sites for a template molecule. Previous studies indicated that molecular imprinting technology could be successfully applied for the preparation of SCLs as ocular drug delivery systems. Previous research, particularly in vivo studies, demonstrated that molecular imprinting is a versatile and effective method in optimizing the drug release behavior and enhancing the loading capacity of SCLs as new ocular drug delivery systems. This review highlights various potentials of molecularly imprinted contact lenses in enhancing the drug-loading capacity and controlling the drug release, compared to other ocular drug delivery systems. We have also studied the effects of contributing factors such as the type of comonomer, template/functional monomer molar ratio, crosslinker concentration in drug-loading capacity, and the release properties of molecularly imprinted hydrogels.     

Practical methods for evaluating the accuracy of the eigenelements of a symmetric matrix

The results of the Householder and QL algorithms for determining the eigenelements of a symmetric matrix, provided by a computer, always contain the errors resulting from floating-point arithmetic round-off error propagation. The Permutation-Perturbation method is a very efficient practical method for evaluating these errors and consequently for estimating the exact significant figures of the eigenelements. But, in the cases of: eigenvalues very close to zero, eigenvalues of widely varying range, and multiple eigenvalues, the Permutation-Perturbation method is not complete. In this paper we propose an algorithm which is able to complete this method.     

Implementation of supervisory control using extended finite-state machines

This article aims at bridging the gap between traditional designs to discrete-event control problems and supervisory control theory of Ramadge and Wonham. We propose to implement supervisory control by extending the plant's finite state machine with Boolean variables, guard formulas and updating functions. Boolean variables are used to encode the supervisor's states, event observation is captured by a set of Boolean functions that update the value of variables, and control is introduced by guarding events with Boolean formulas. The framework developed in this work is fundamental in our ongoing research on communication between supervisors in a distributed discrete-event system.     

Effect of nano-sized calcium carbonate on cure kinetics and properties of polyester/epoxy blend powder coatings

Today's strict environmental laws pose significant challenges for coating's formulators to look for eco-friendly products. Powder coatings, particularly polyester/epoxy blends have demonstrated their ability as alternatives to traditional solvent-borne coatings. Recently, the use of nanoparticles such as nano-CaCO₃ (nCaCO₃) has been suggested as a beneficial strategy towards powder coating application with improved properties. Here, we study the effect of nCaCO₃ on morphology, cure behavior, adhesion and hardness of polyester/epoxy systems. The nanoparticles shape, size and dispersion state were investigated through X-ray diffraction (XRD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM) methods. Furthermore, isothermal cure characterization of the neat and filled systems was performed using a torque rheometer. The most important finding based on the rheological studies was the catalytic effect of nCaCO₃ on cure reaction of polyester/epoxy, leading to the shorter curing time. Moreover, the kinetic analyses of rheograms revealed a marked decrease in the activation energy of the cure process upon raising nCaCO₃ content. Interestingly, pull-off adhesion and hardness tests showed that the hardness and adhesion strength were dramatically increased by the addition of nCaCO₃ into the polyester/epoxy system compared to pure blend resin. Therefore, considering the strong competition in powder coating market, the use of nCaCO₃ as a commercial and inexpensive nanofiller is necessary not only to reduce the dwell time which has benefits in terms of the energy consumption and economics, but also to improve the performance of final polyester/epoxy coating.     

A generalised optimal linear quadratic tracker with universal applications – part 1: continuous-time systems

This paper presents a generalised optimal linear quadratic analog tracker (LQAT) with universal applications for the continuous-time (CT) systems. This includes: (1) a generalised optimal LQAT design for the system with the pre-specified trajectories of the output and the control input and additionally with both the input-to-output direct-feedthrough term and known/estimated system disturbances or extra input/output signals; (2) a new optimal filter-shaped proportional plus integral state-feedback LQAT design for non-square non-minimum phase CT systems to achieve a minimum phase-like tracking performance; (3) a new approach for computing the control zeros of the given non-square CT system; and (4) a one-learning-epoch input-constrained iterative learning LQAT design for the repetitive CT system.     

Facile synthesis and characterization of CdTiO<Subscript>3</Subscript> nanoparticles by Pechini sol–gel method

In this work, CdTiO₃ nanoparticles were synthesized through reaction between Cd(CH₃COO)₂.2H₂O, Ti(OC₄H₉)₄, trimesic acid as a new chelating agent and ethanol as solvent by Pechini sol–gel method. X-ray diffraction (XRD) patterns showed that CdTiO₃ nanostructures have rhombohedral structure with diameter of about 35.61 nm. The structure, morphology and size of CdTiO₃ nanoparticles were characterized by FT-IR, XRD, SEM and EDAX. The optical properties of the products were studied by DRS. Based on the results of experiments, it was found that temperature and time of calcination, pH and the solvent of reaction are important parameters for formation of CdTiO₃ nanoparticles. Utilizing trimesic acid (benzene-1,3,5-tricarboxylic acid) as a new chelating agent for preparation of CdTiO₃ nanostructures was initiative of this work.     

Optimisation of probiotic yoghurt production enriched with phytosterols

To optimise the formulation of phytosterol‐enriched probiotic yoghurt, the effect of different concentrations of phytosterols, fat and the probiotic inoculation rate on the survival of Lactobacillus acidophilus LA‐5, Bifidobacterium lactis BB‐12 and physicochemical indices over 14 days of storage was explored. Data analysis showed that the phytosterol concentration and fat content were two crucial factors affecting probiotic viability. Addition of phytosterols had no adverse effect on the overall scores for sensory attributes. Regarding maximisation of viability and storage time, the optimum conditions were found to be fat = 8.07% (w/v), phytosterol = 18 g/L, probiotic inoculation rate = 71.42 mg/L and storage time = 12 days.