Radiation induced lipid oxidation in fish

Summary Oxidative rancidity in herring and redfish was studied as a function of the applied irradiation dose, the storage time and storage temperature and the packaging conditions. — Measurements of the TBA (thiobarbituric acid) value and the peroxide value were used to evaluate the degree of oxidation of lipids, and were related with sensory scores. — Especially for the fatty fish species (herring) irradiation accelerated lipid oxidation and induced oxidative rancidity. Irradiation of vacuum-packed herring fillets and subsequent storage at +2° C seems to be an interesting process. For the experiments conducted on a semi-fatty fish (redfish), oxidative rancidity was never the limiting factor for organoleptic acceptability.

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Bestrahlungsinduzierte Fettoxydation in Fisch

Zusammenfassung Die oxydative Ranzigkeit in Hering und Rotbarsch wurde als eine Funktion der angewandten Bestrahlungsdosis, der Lagerungszeit und-temperatur und der Verpackungsbedingungen studiert. — Die Messung der TBS (Thiobarbitursäure)-Zahl und der Peroxydzahl wurde zur Bewertung des Oxydationszustandes der Lipide benutzt und mit sensorischen Prüfungen verglichen. Besonders bei fetten Fischsorten (Hering) werden durch Bestrahlung die Fettoxydation und die induzierte oxydative Ranzigkeit beschleunigt. Die Bestrahlung von vacuumverpackten Heringfilets mit anschließender Lagerung bei +2° C scheint ein technologisch interessantes Verfahren zu sein. Bei halbfettem Fisch (Rotbarsch) war die oxydative Ranzigkeit niemals der beschränkende Faktor für die sensorische Brauchbarkeit.

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Research partly supported by the International Atomic Energy Agency, Vienna

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Aangesteld Navorser, N.F.W.O. (National Research Foundation)     

Predicting the headspace oxygen level due to oxygen permeation across multilayer polymer packaging materials: A practical software simulation tool

The shelf life of a food product is largely determined by its chemical and microbiological stability. In this respect, the gas composition surrounding a packaged product plays a major role. Modified Atmosphere Packaging (MAP) is a packaging technique that usually reduces the headspace oxygen to a preferable minimum for most food products. Besides the residual oxygen, the O₂-permeability of the packaging material is also important, as it determines the amount of oxygen permeating into the package during storage. This paper describes the development of a practical software simulation tool to predict the amount of oxygen permeating into the headspace during storage for a variety of multilayer packaging configurations. The simulation tool gives access to simulation models for mono- and multilayer films, trays covered with top foils and bottles with caps. The user can compose his/her own (multilayer) packaging material and check the oxygen ingress over time for different temperature conditions for all packaging configurations.Industrial relevanceThe software simulation tool is of industrial relevance to food companies, as they can use it to select or compare different films, but also to underpin their choice for a certain packaging material with regard to the sensitivity of the food product to oxygen and the desirable shelf life. The simulation program also provides food companies with information about the influence of storage conditions, like time and temperature, on the ingress of oxygen in their food package throughout the storage-distribution chain. On the other hand, it can also be used by packaging suppliers to predict the oxygen permeability in the optimization process of new films and as a client support tool.     

Random Field Modeling of Elastic Properties Using Homogenization

This paper addresses the random field characterization of elastic properties. Consistent random field properties of a continuum are derived from a simple stochastic micromechanical model of the continuum. Existing displacement-based techniques to homogenize the discrete microstructure are discussed and a new force-based technique is introduced. The stochastic features of a micromechanically consistent continuum can be considerably different from those based on a straightforward randomization of deterministic constitutive laws. Examples indicate the relevance for structural reliability. The impact of uncertainties associated with selecting micromechanical models is assessed.     

Automatic 3-D segmentation of internal structures of the head in MR images using a combination of similarity and free-form transformations: Part I, Methodology and validation on normal subjects

The study presented in this paper tests the hypothesis that the combination of a global similarity transformation and local free-form deformations can be used for the accurate segmentation of internal structures in MR images of the brain. To quantitatively evaluate our approach, the entire brain, the cerebellum, and the head of the caudate have been segmented manually by two raters on one of the volumes (the reference volume) and mapped back onto all the other volumes, using the computed transformations. The contours so obtained have been compared to contours drawn manually around the structures of interest in each individual brain. Manual delineation was performed twice by the same two raters to test inter- and intrarater variability. For the brain and the cerebellum, results indicate that for each rater, contours obtained manually and contours obtained automatically by deforming his own atlas are virtually indistinguishable. Furthermore, contours obtained manually by one rater and contours obtained automatically by deforming this rater's own atlas are more similar than contours obtained manually by two raters. For the caudate, manual intra- and interrater similarity indexes remain slightly better than manual versus automatic indexes, mainly because of the spatial resolution of the images used in this study. Qualitative results also suggest that this method can be used for the segmentation of more complex structures, such as the hippocampus.     

Fatty acid profile and affective dysregulation in irritable bowel syndrome

Irritable bowel syndrome (IBS) is a functional gastrointestinal disorder with a high co-occurrence with affective dysregulation. Affective disorders have been associated with specific changes in the PUFA and cholesterol profile. In IBS, similar changes may be present as have been reported in patients with affective disorders. This exploratory study investigates (i) the level of affective dysregulation (AD) in IBS patients and healthy controls; (ii) PUFA and cholesterol profiles in IBS patients compared with controls; and (iii) associations between PUFA and cholesterol parameters with the level of AD. Blood samples were obtained for determination of the FA composition of plasma phospholipids and serum cholesterol in 23 diarrheapredominant IBS patients and 23 healthy matched controls. AD was scored using the Symptom Check List depression scale, the Hospital Anxiety and Depression Scale, and the Hamilton Depression Rating Scale. The level of AD was higher in IBS patients compared with controls. PUFA and cholesterol profiles did not differ significantly between groups. Total n−3 PUFA and cholesterol were significantly negatively associated and the ratio of n−6 to n−3 PUFA and the ratio of arachidonic acid to EPA were significantly positively associated with the level of AD. The findings of the present study reveal that AD was higher in IBS patients compared with healthy controls and that changes in PUFA and cholesterol profiles were significantly associated with the level of AD. These results warrant further studies regarding the role of PUFA and cholesterol status in the co-occurrence of AD and functional gastrointestinal disorders.     

Structured prediction with reinforcement learning

We formalize the problem of Structured Prediction as a Reinforcement Learning task. We first define a Structured Prediction Markov Decision Process (SP-MDP), an instantiation of Markov Decision Processes for Structured Prediction and show that learning an optimal policy for this SP-MDP is equivalent to minimizing the empirical loss. This link between the supervised learning formulation of structured prediction and reinforcement learning (RL) allows us to use approximate RL methods for learning the policy. The proposed model makes weak assumptions both on the nature of the Structured Prediction problem and on the supervision process. It does not make any assumption on the decomposition of loss functions, on data encoding, or on the availability of optimal policies for training. It then allows us to cope with a large range of structured prediction problems. Besides, it scales well and can be used for solving both complex and large-scale real-world problems. We describe two series of experiments. The first one provides an analysis of RL on classical sequence prediction benchmarks and compares our approach with state-of-the-art SP algorithms. The second one introduces a tree transformation problem where most previous models fail. This is a complex instance of the general labeled tree mapping problem. We show that RL exploration is effective and leads to successful results on this challenging task. This is a clear confirmation that RL could be used for large size and complex structured prediction problems.     

Negligible Effect of Process-Induced Strain on Intrinsic NBTI Behavior

In this letter, we investigate the effects of process-induced strain on negative bias temperature instability (NBTI) by performing a comparative study of devices with and without process-induced strain for poly-Si/SiON gate stacks. Devices with SiGe source/drain with different processing sequences and devices with a combination of SiGe S/D and compressive contact etch stop layer (CESL) were studied and compared to reference devices. We decouple the effect of processing conditions in order to ensure a correct interpretation of the results. In contrast with the previous reports, which did not consider the impact of processing conditions, this letter demonstrates that, when initial threshold voltage differences are taken into account and comparisons are performed at the same oxide electric field, no significant degradation of intrinsic NBTI behavior is found for devices with a process-induced strain. In addition, we performed an Arrhenius study showing similar activation energies for devices with and without process-induced strain, suggesting similar degradation mechanism. The results indicate that process-induced strain does not create favorable conditions for additional interface state creation     

Removal of Heavy Metal Impurities from Dredged River Sediment

This article shows the results of a study that aims to remove the sediment fraction containing heavy metals from river sediment by flotation. Different parameters such as pH, flotation time, different collectors, distilled water, tap water, and different salts were investigated to achieve a high separation efficiency. Explanations are suggested for the obtained results. Results of flotation revealed that 63 % by weight of the input dredged sediment can be safely and successfully separated, thus, meeting the standard environmental requirement of current Flemish (Belgium) regulation “bodemsaneringsdecreet” (February 1995). This dredged fraction could not be achieved before a flotation time of 15 min. Increasing flotation time would impart less metal content but with a lower yield. In the case of applying the settling technique, 55 % by weight of the dredged sample meeting the same standard specification was obtained. Results are explained in the light of a model, which assumes that sediment contains organic matter together with heavy metals, clay, and sand. Upon aeration, air bubbles are adsorbed on hydrophobic particles, which carry them up to the froth layer with the hydrophilic particles left behind in the pulp. The use of an organic collector has a minor effect on flotation process. Results of the settling technique are discussed.