Turbo EP-based Equalization: a Filter-Type Implementation

This manuscript has been submitted to Transactions on Communications on September 7, 2017; revised on January 10, 2018 and March 27, 2018; and accepted on April 25, 2018 We propose a novel filter-type equalizer to improve the solution of the linear minimum-mean squared-error (LMMSE) turbo equalizer, with computational complexity constrained to be quadratic in the filter length. When high-order modulations and/or large memory channels are used the optimal BCJR equalizer is unavailable, due to its computational complexity. In this scenario, the filter-type LMMSE turbo equalization exhibits a good performance compared to other approximations. In this paper, we show that this solution can be significantly improved by using expectation propagation (EP) in the estimation of the a posteriori probabilities. First, it yields a more accurate estimation of the extrinsic distribution to be sent to the channel decoder. Second, compared to other solutions based on EP the computational complexity of the proposed solution is constrained to be quadratic in the length of the finite impulse response (FIR). In addition, we review previous EP-based turbo equalization implementations. Instead of considering default uniform priors we exploit the outputs of the decoder. Some simulation results are included to show that this new EP-based filter remarkably outperforms the turbo approach of previous versions of the EP algorithm and also improves the LMMSE solution, with and without turbo equalization

Mixing properties of fibre-enriched wheat bread doughs: A response surface methodology study

8 pages, 2 figures, 5 tables.-- Published online 29 December 2005.-- The original publication is available at www.springerlink.comFibre-enriched baked goods have increasingly become a convenient carrier for dietary fibre. However, the detrimental effect of fibres on dough rheology and bread quality continuously encourages food technologists to look for new fibres. The effect of several fibres (Fibruline, Fibrex, Exafine and Swelite) from different sources (chicory roots, sugar beet and pea) on dough mixing properties when added singly or in combination has been investigated by applying a response surface methodology to a Draper-Lin small composite design of fibre-enriched wheat dough samples. Major effects were induced on water absorption by Fibrex that led to a significant increase of this parameter, accompanied by a softening effect on the dough, more noticeable when an excess of mixing was applied. Conversely, Exafine increased water absorption without affecting the consistency and stability of dough, which even improved when combined with Swelite. Fibruline showed little effect on dough mixing parameters, but showed synergistic effects with pea fibres. The overall result indicates that the use of an optimised combination of fibres in the formulation of fibre-enriched dough allow improving dough functionality during processing.Peer reviewe

Antimicrobial composite wound dressing

Nowadays, a wound dressing is no longer a passive material, it must interact with the wound and improve the healing process. In fact, the actual requirements for a wound dressing are quite challenging. To achieve these demanding goal, wound dressing’ research have been focus on the development of composites that combine the best of two or more polymeric materials. Thus, our group developed a composite material of cotton functionalized with hydroxypropyl methylcellulose / cyclodextrins hydrogel to be used as antimicrobial wound dressing. Hydrogel polymer will improve the wearability and the drug delivery capacity of cotton textiles. And cotton will enhance the mechanical properties of hydrogel, facilitating the handle process. The composite synthesis was performed by one-step chemical crosslinking. The reaction parameters, such as crosslinker concentration and polymeric solution concentration, were optimized. The obtained composites were characterized base on their physicochemical and biological properties. To the best of our knowledge, loading and release of gallic acid (as antibacterial agent) into composites wound dressings, and its release for control wound infections, have not been evaluated until now. The developed composites have the combined properties of cotton and hydrogel. The gallic acid was successfully loaded into the polymeric network, and it release was sustained for 48 h. The loaded composites can destroy bacterial cells preserving the gallic acid antibacterial activity. Thus, the developed composites showed suitable properties for the incorporation of gallic acid and utilization as antibacterial wound dressing.TSSiPRO—NORTE-01-0145-FEDER-000015—supported by the regional operational program NORTE 2020, under the PORTUGAL 2020 Partnership Agreement, through the European Regional Development Fund;info:eu-repo/semantics/publishedVersio

Gallic acid and cyclodextrins : inclusion complexes and antimicrobial activity

Gallic acid (GA), or 3,4,5-trihydroxybenzoic acid, is the commonest and simplest phenolic acid, with just one aromatic ring. This phenolic molecule has been described as antioxidant, anti-inflammatory and anti-tumour, also, antimicrobial and anti-fungal activity has been attributed to it. Besides all the GA biological activities, this compound is cheap, due to the easy plant extraction, and non-toxic. Thus, this phenolic acid has been widely used in food, drugs and cosmetic industry. GA, as other phenolic compounds, is susceptible to environmental factors which may lead to the losing their structural integrity and bioactivity. This can be overcome by the encapsulation with cyclodextrins (CD). They are cyclic oligosaccharides arising from the degradation of starch; inexpensive and friendly to humans. CD are able to form an inclusion complex with a wide range of bioactive molecules, including hydrophobic ones, protect and modulate their release. In the present work, the formation of an inclusion complex (IC) between βCD, HPβCD (2-Hydroxypropyl-β-cyclodextrin) or MβCD (methyl-β-cyclodextrin) and GA was analysed by UV spectrophotometry. The antimicrobial activity of the complexes was also assessed, by qualitative and quantitative methods. The influence of the buffer and pH on the formation of the IC and on the GA antimicrobial activity was also tested. The IC formation was analysed in 2 buffer solutions (K2HPO4/ KH2PO4 and H3PO4/NaOH). The GA and IC absorbance spectrum showed different appearances depending on the buffer used. When K2HPO4/ KH2PO4 was used, the IC spectrum presented some alterations on the λmax comparatively to the GA spectrum. Since, the GA and ICs spectra obtained for the H3PO4/NaOH were similar, this buffer was selected. The IC formation between GA and βCD, HPβCD or MβCD was analysed at pH 5, 7 and 8. Based on the results it was clear that the pH used affected the IC formation in the conditions tested. The βCD formed IC 1:1 with GA for all pH values, being the pH5 the most favourable. The same was observed for MβCD, but these CD had the lowest values for the association constant, meaning that the IC formation between MβCD and GA is not very efficient. Regarding the HPβCD, in neutral pH the IC formed was 1:2 and for the others pH was 1:1, pH5 was the most favourable for the IC formation and pH7 the least. The antimicrobial activity was assessed for the best combinations of GA/CD (βCD pH5 and pH7; HPβCD pH5 and pH8). For all the IC tested, the antimicrobial activity of GA was improved or alike to the GA without encapsulation. To the authors knowledge, the IC formation between HPβCD or MβCD and GA has not been reported until know, as well as the antimicrobial activity of the IC βCD/GA and HPβCD/GA

Comparative study of silicone-hydrogel contact lenses surfaces before and after wear using atomic force microscopy

Purpose: The aim of this study was to analyze surface changes of three silicone-hydrogel contact lenses after daily wear. The lenses used in this study were balafilcon A, lotrafilcon B (both surface-treated), and galyfilcon A (non surface-treated). Methods: To understand how and where proteins, lipids, and other contaminants change contact lenses, surface roughness was assessed through Atomic Force Microscopy Tapping ModeTM. Roughness parameters were Mean Surface roughness (Ra), Mean-square-roughness (Rq), and Maximum roughness (Rmax). The surface topography of unworn and worn lenses was also mapped in great detail. Results: Contact lenses roughness parameters exhibited different values before and after wear and the surface appearance also changed. After wear, balafilcon A and galyfilcon A showed a significant increase on surface roughness parameters, being this increase more accentuated to galyfilcon A. In lotrafilcon B materials no significant changes were observed with wear. Conclusions: The present study suggests that surface treatment of silicone-hydrogel contact lenses can play a role in the prevention of a significant increase in roughness, and contribute to the better clinical tolerance of these lenses.University of PortoIBM

The effect of lens wear on refractive index of conventional hydrogel and silicone-hydrogel contact lenses: a comparative study

Purpose: The purpose of this work was to evaluate the ability of four silicone-hydrogel contact lenses (galyfilcon A, balafilcon A, lotrafilcon A and lotrafilcon B) to retain their equilibrium water content before and after wear, through measurements of refractive index and compare with that of a conventional disposable hydrogel contact lens (etafilcon A). Methods: The refractive indices of 115 contact lenses were measured using an automated refractometer (CLR 12-70, Index Instruments, Cambridge, U.K.) before and after a schedule of daily wear by 58 patients for 30 days in the case of silicone-hydrogel lenses and 15 days for the conventional contact lenses. Results: In the silicone-hydrogel contact lenses the changes on the refractive indices were not statistically significant, however after being worn the refractive index of the conventional etalfilcon A hydrogel contact lens increased significantly ( p < 0.001). Conclusion: The results presented here show that after being worn the silicone-hydrogel contact lens, show more capacity to retain or to reach their initial equilibrium water content than conventional hydrogel contact lenses. This suggests that the silicone-hydrogel contact lenses are less susceptible to spoilation over time maintaining its biocompatibility and contributing to the clinical success of lens performance.Vision and Johnson & Johnson.Bausch & Lom

Assessment of antimicrobial activity of textiles for wound dressing: methodology optimization

Normally, the skin is capable of restore the tissue integrity, after wound injury. However, the deposition of bacteria on the wound site results on infection causing pain and healing delay. To control bacteria proliferation, antimicrobial textiles have been developed, and the assessment of their activity is a required step. Although, several standard methods were published to assess textiles antimicrobial activity, they are time and material consuming and have some shortcomings with regard to the real conditions of use. Therefore, the aim of this work was to optimize the method described on JIS L 1902:2008-Testing for antibacterial activity and efficacy on textile products, the most commonly used standard. Two textile samples were used: A-cotton without treatment (control) and B-cotton with 10% of the recommend concentration of Ruco-bac AGP. The microorganism used was Staphylococcus aureus-ATCC 6538. The first improvement was sample size. On the qualitative method, square samples with 1x1cm2 were used instead 2.5x2.5cm2 (suggested by the standard). For sample A no antimicrobial activity was observed and for sample B the halo size was similar for both sizes used. For the quantitative method, the samples used had 0.4g (standard suggestion) and 0.1g. Sample A had the same bacterial growth before and after contact with the fabric and sample B had no bacterial growth. With this improvement, the amount of sample and solutions need for the test was reduced four times. To reduce the use of disposable material, instead of 50mL falcons, 6 well plates were used. In this case, no bacteria were recovered from the sample A after incubation period on 6 well plates. These means, that the centrifugation is a crucial step to detach all bacteria from the fabric. The effect of the bacterial inoculum volume was also assessed. Three inoculum volumes (250, 100 and 50µL) were added to 0,1g samples. No significant differences were observed for both samples. A healthy skin has 105bacteria/cm2 and up to this value it is considered that the skin is infected. Therefore, 3 inoculum concentrations were tested-3x105, 3x106, 3x107cell/mL. The results showed that the inoculum concentration had no significant changes for both samples after the incubation period. In conclusion, it is possible to use samples 4 times smaller than the standard suggestion, use higher inoculum volume to simulate wound exudate and higher concentration, to accurately predict the sample behaviour on an infected skin

The effect of silicone-hydrogel and conventional hydrogel contact lenses wear on the tear film: a comparison between de lenses

Purpose: The aim of this study was to evaluate the effect of one conventional hydrogel and four silicone-hydrogel contact lenses of 6-months daily wear on the quantity and stability of the tear film. The tests were performed with a group of patients with no previous contact lenses experience before and after wear on 96 eyes. Methods: The contact lenses tested were: 19 Galyfilcon A (Acuvue® Advance™), 15 Balafilcon A (PureVision™), 20 Lotrafilcon A (Focus® Night & Day™), 14 Lotrafilcon B (O2Optix™) and 28 Etalfilcon A (Acuvue®). Each silicone-hydrogel contact lens was used for 1 month and the conventional hydrogel for 15 days. Every patient used a different lens in each eye. Tear film stability was monitored by tear Break-up-time (BUT) and Non Invasive Break Up Time (NiBUT) and tear volume was measured by the Total Tear Meniscus Height and the Red Phenol Test. Results: The following tables summarize the difference between the measurements obtained in the first and in the last day of wear of each contact lens brand and the results were analyzed comparing the conventional hydrogel and the siliconehydrogel contact lenses (Table 1, 2, and 3), the lenses belonging to the first generation of silicone-hydrogel contact lenses (table 4) and the lenses belonging to the second generation of silicone-hydrogel (Table 5). The significance (p value) of 0.05 is considered statistically significant. Conclusions: Although there are some differences between the lenses, there are no statistically significant differences between the lenses and measurements obtained before and after contact lenses wear on the tear film tests.Objectivo: Avaliar o efeito de 6 meses de uso diário de uma lente de contacto de hidrogel convencional e quatro lentes de contacto de silicone-hidrogel na qualidade e estabilidade do filme lacrimal. Os testes foram realizados num grupo de pacientes (96 olhos) sem experiência prévia de uso de lentes de contacto, antes e depois do período de uso das lentes. Material e Métodos: As lentes de contacto estudadas foram: 19 Galyfilcon A (Acuvue® Advance™), 15 Balafilcon A (PureVision™), 20 Lotrafilcon A (Focus® Night & Day™), 14 Lotrafilcon B (O2Optix™) e 28 Etalfilcon A (Acuvue®). Cada lente de silicone-hidrogel foi usada durante 1 mês e a lente de hidrogel convencional durante 15 dias. Todos os pacientes usaram uma lente diferente em cada olho. A estabilidade do filme lacrimal foi avaliada pelo teste de ruptura lacrimal (BUT) e pelo teste de ruptura lacrimal não invasivo (NIBUT). O volume lacrimal foi medido pala altura total do menisco lacrimal e pelo teste vermelho fenol (Red Phenol Test) Resultados: Nas tabelas seguintes apresenta-se a diferença entre as medidas obtidas no 1º e último dia de uso para cada marca de lente de contacto e os resultados foram analisados comparando a lente de contacto hidrogel convencional com as lentes de silicone-hidrogel (Tabela 1, 2 e 3), as lentes pertencentes à 1ª geração de lentes de silicone-hidrogel (Tabela 4) e as lentes que pertencem à 2ª geração das lentes de silicone-hidrogel (Tabela 5). O valor da significância (p) é considerada estatisticamente significativa quando ≤0.05. Conclusões: Embora existam algumas diferenças entre as lentes de contacto estudadas, não há diferenças estatisticamente significativas entre os valores obtidos nos testes de avaliação do filme lacrimal antes e depois do uso das lentes de contacto

Alterações na transmitância UV-Visível induzidas pelo uso de lentes de contacto de silicone-hidrogel

Fundação para a Ciência e a Tecnologia (FCT) through Centro de Física da U