Methodology to evaluate variations in piezoelectric constants after aging process

ABSTRACT

Piezoelectric ceramic properties change with time. Detected aging effects for PZT ceramics are; the difference in the value of the dielectric constants diminishes, whereas dielectric losses and elastic stiffness increases. In this work, an optimisation technique based on adjusting a finite element model to reproduce the complex impedance curves of a resonant piezoceramic disk is analysed aiming to detect changes due to aging. This technique allows estimating all material parameters, both their real and imaginary parts. The optimisation uses the constitutive equations of the piezoelectric effect in the linear regime. The evolution of elastic, piezoelectric and dielectric constants is evaluated after 5 years of aging. To compute the ten complex parameters, the piezoelectric model is adjusted to minimise the difference between finite element simulations and the experimental data. Results presented here, show that the proposed technique is sensitive enough to detect changes in the individual parameters due to aging process.     

Application of β-Sitosterol + γ-Oryzanol-Structured Organogel as Migration Barrier in Filled Chocolate Products

Oil migration in filled pralines is a phenomenon that is highly correlated with the occurrence of chocolate bloom. In this study the potential to suppress or prevent oil migration by incorporation of sterol/sterolster-structured organogels was evaluated. Different quantities, 2.5 or 14% (w/w), of gel with structurant levels of either 10 or 25% (w/w) were studied in a layered model system. The gel was either a part of the nougat or of the chocolate phase, or as a separate layer. Samples were monitored regularly for a period of 24 weeks at storage temperatures of 10, 18 and 28 °C. The amount of migrated oil was determined via DSC analysis of a surface sample. The results indicate that, despite the additional oil brought into the system via the oleogel, the level of oil found in the chocolate layer is reduced through the presence of the gel. In particular, the three-layer system and gelled chocolate appear to be promising routes to either suppress oil migration or improve nutritional profiles by incorporation of liquid oils.     

Fruits and vegetables intake and characteristics associated among adolescents from Southern Brazil

Background

Pseudomonas aeruginosa adhesion to animal/human cells for infection establishment involves adhesive proteins, including its galactose- and fucose-binding lectins PA-IL (LecA) and PA-IIL (LecB). The lectin binding to the target-cell receptors may be blocked by compatible glycans that compete with those of the receptors, functioning as anti-adhesion glycodecoys. The anti-adhesion treatment is of the utmost importance for abrogating devastating antibiotic-resistant P. aeruginosa infections in immunodeficient and cystic fibrosis (CF) patients. This strategy functions in nature in protecting embryos and neonates. We have shown that PA-IL, PA-IIL, and also CV-IIL (a PA-IIL homolog produced in the related pathogen Chromobacterium violaceum) are highly useful for revealing natural glycodecoys that surround embryos in diverse avian eggs and are supplied to neonates in milks and royal jelly. In the present study, these lectins were used as probes to search for seed embryo-protecting glycodecoys.

Methods

The lectin-blocking glycodecoy activities were shown by the hemagglutination-inhibition test. Lectin-binding glycoproteins were detected by Western blotting with peroxidase-labeled lectins.

Results

The present work reports the finding - by using PA-IL, PA-IIL, and CV-IIL - of rich glycodecoy activities of low (< 10 KDa) and high MW (> 10 kDa) compounds (including glycoproteins) in extracts of cashew, cocoa, coffee, pumpkin, and tomato seeds, resembling those of avian egg whites, mammal milks, and royal jelly.

Conclusions

Edible seed extracts possess lectin-blocking glycodecoys that might protect their embryos from infections and also might be useful for hampering human and animal infections.     

Characterization of Oleogels Based on Waxes and Their Hydrolyzates

In this paper, the structuring of liquid oils, also known as oleogelation, is systematically investigated for the first time using a quasi-quaternary mixing system approach. Native waxes with different quantities of wax esters (WE), n-alkanes (hydrocarbons (HC)), fatty acids (FA), and fatty alcohols (FaOH) are applied in mixtures with hydrolyzed waxes to systematically change the composition. Hydrolyzed waxes contain high levels of FA and FaOH. The model systems are investigated on microscopic level (brightfield light microscopy (BFM), cryogenic scanning electron microscopy (cryo-SEM)) as well as on their macroscopic properties (rheology, gel hardness) and calorimetric behavior (differential scanning calorimetry (DSC)). It is found that sunflower wax (SFW)-based gels (12% structurant) become less hard on any admixture. Beeswax (BW)-based gels show significant increases in hardness when 25% and 50% (w/w) hydrolyzate are admixed. This could be related to stepwise crystallization. Further analysis reveals that the dissolution/melting behavior of the wax ester mixtures can be surprisingly well described as ideal solubility of a single pseudocomponent. The approach to unravel the individual contributions of the different species present in waxes is successful and marks a first step to better understand the systematic of wax functionality as oleogelators. Practical Application: The substitution of hardstock fats in structured oil phases is of interest for two reasons. The improved nutritional profile oleogels offer are beneficial for public health while the elimination of palm oil based ingredients appears to be a general public desire. Among the technical solutions for non-TAG oil structuring waxes are very promising. This is primarily due to their availability, prior consumption, potentially low cost for functionality. Currently waxes are technically and scientifically wrongly treated as single components. In order to better utilize the potential of waxes and design future sourcing strategies it is necessary to understand the wax functionality at a compositional/molecular level. This contribution marks the first step into this direction by considering classes of molecules with respect to their contribution to functionality. This understanding is considered as a key for future compositional design.     

Identification of tet(M) in two Lactococcus lactis strains isolated from a Spanish traditional starter-free cheese made of raw milk and conjugative transfer of tetracycline resistance to lactococci and enterococci

Specific PCR and sequencing showed that a tet(M) gene was present in two tetracycline-resistant Lactococcus lactis strains isolated from a raw milk, starter-free cheese. Hybridisation experiments using as a probe an internal segment of the gene obtained by PCR associated tet(M) with plasmids of around the same size (30 kbp) in both strains. Molecular analysis of the tetracycline resistance loci, including the upstream and downstream regions of the genes, showed them to be identical to one other and to the tet(M) encoded by the conjugative transposon Tn916. Amplification of Tn916-derived segments suggested the transposon was complete in the two L. lactis strains. Further, curing of the tetracycline resistance was accompanied by a reduction in size of the plasmids comparable to that expected for Tn916. Tetracycline resistance could be transferred by conjugation to plasmid-free Lactococcus and Enterococcus strains. However, no plasmid DNA was detected among the transconjugants while both tet(M) and transposon-related sequences were amplified by PCR. This suggested that only the transposon was mobilized.     

Pipeline Heating Method Based on Optimal Control and State Estimation

In the production of oil and gas in deep waters, the flow of the produced hydrocarbon through pipelines is a challenging problem. High hydrostatic pressures and low seabed temperatures may result in the formation of solid deposits, which in critical operating conditions like unplanned shutdowns can cause pipeline blockages. One of the possible methods for flow assurance, which can be jointly used with other approaches, is to heat the pipeline. This design concept aims at heating the produced fluid, if needed, to above a safe reference temperature in order to avoid the formation of solid deposits. The objective of this article is to utilize the particle filter method for the solution of a state estimation problem, in which the state variables are considered as the transient temperatures within a pipeline cross section. In addition, the minimum temperature in the region, predicted with the particle filter method, is used in the optimal control theory as a design tool for a typical heating system, during simulated shutdown conditions. An application example is presented to illustrate the control of the minimum temperature in the region, from an observer based on the particle filter method, where temperature measurements are assumed to be available on the external surface of the pipeline.     

Characterization of red wines from South America based on sensory properties and antioxidant activity

BACKGROUND: It is widely accepted that red wines constitute one of the most important sources of dietary polyphenolic antioxidants. However, it is still not known how some variables such as variety, vintage, country of origin, and retail price are associated with the antioxidant activity and sensory profile of South American red wines. In this regard, 80 samples produced in Brazil, Chile and Argentina were assessed in relation to their sensory properties, color and in vitro antioxidant activity, and results were subjected to multivariate statistical techniques. RESULTS: Samples were grouped in clusters, characterized by high, intermediate and low in vitro antioxidant activity, sensory properties and prices. It was possible to observe that wines with high antioxidant activity were associated to high retail prices and overall perception of sensory quality. CONCLUSION: South American wines produced from Vitis vinifera such as Syrah, Malbec and Cabernet Sauvignon had higher in vitro antioxidant activity and also higher sensory quality than wines produced from Vitis labrusca. This result was independent of vintage (2002‐2010), corroborating the idea that the same grape varietal, even when produced in different years, displays similar sensory characteristics and antioxidant activity. Copyright © 2011 Society of Chemical Industry     

CFL-Violating Numerical Schemes for a Two-Fluid Model

In this paper we propose a class of linearly implicit numerical schemes for a two-phase flow model, allowing for violation of the CFL-criterion for all waves. Based on the Weakly Implixit Mixture Flux (WIMF) approach [SIAM J. Sci. Comput., 26 (2005), pp. 1449–1484], we here develop an extension denoted as Strongly Implicit Mixture Flux (SIMF). Whereas the WIMF schemes are restricted by a weak CFL condition which relates time steps to the fluid velocity, the SIMF schemes are able to break the CFL conditions corresponding to both the sonic and advective velocities. The schemes possess some desirable features compared to current industrial pressure-based codes. They allow for sequential updating of the momentum and mass variables on a nonstaggered grid by solving two sparse linear systems. The schemes are conservative in all convective fluxes and consistency between the mass variables and pressure is formally maintained. Numerical experiments are presented to shed light on the inherent differences between the WIMF and SIMF families of schemes. In particular, we demonstrate that the WIMF scheme is able to give an exact resolution of a moving contact discontinuity. The SIMF schemes do not possess the “exact resolution” property of WIMF, however, the ability to take larger time steps can be exploited so that more efficient calculations can be made when accurate resolution of sharp fronts is not essential, e.g. to calculate steady state solutions.     

3D reconstruction based on hard tissue microtome cross-section pictures in dentistry

The aim of this study was to examine the accuracy of the computerized 3D surface analyzing and volume measuring method in dentistry. Two different types of test objects were used in the first part of the measurements. Each sample of the two groups was cross-sectioned using a hard tissue microtome. The sections were photographed on both sides and were projected on a graphical tablet and analyzed using a computer program. The measured and calculated parameters were compared. In the second part, 200 microm thick horizontal sections were prepared from 11 human incisor roots using the hard tissue microtome. This way, five sections were prepared from the apical 2 mm of each root. The effects of section thickness and number were modeled by decreasing the inclusion rate of the obtained number of sections from 10 to 2 and its influence on the calculated results was determined. This method was suitable for the approximation and analysis of 3D parameters. The results indicated that using 200-300 microm section thickness, the measured values were approximately 8-21% lower than the real parameters.