Seasonal variation of seaweed components and novel biological function of fucoidan extracted from brown algae in Quebec

Fucus vesiculosus et Ascophyllum nodosum sont des algues brunes comestibles et abondantes au Québec. Cependant, elles ont été négligées en raison de leur valeur potentielle inconnue et de la période de récolte limitée. Afin de valider leur utilité, la composition chimique de ces algues et l’activité inhibitrice des enzymes digestives de l'amidon par les fucoïdanes extraits de ces deux espèces d'algues ont été étudiés en fonction de la saison. Les composants principaux des algues sont dans l’ordre: les polysaccharides> minéraux> protéines> fucoïdane> lipides> > composés phénoliques, et leur quantité est très variable selon la période de récolte. F. vesiculosus contenait une plus grande quantité de protéines et de minéraux, alors que A. nodosum avait relativement plus de polysaccharides. Par conséquent, F. vesiculosus serait plus avantageux comme source d’éléments nutritifs. L’algue A. nodosum récoltée en Juillet a permis d’obtenir le fucoïdane ayant la pureté la plus élevée et le meilleur rendement. Les fucoïdanes extraits des deux espèces d’algues ont inhibé l’activité de l’α-glucosidase alors que seul celui extrait d’A. nodosum a pu, de plus, inhiber l’α-amylase. Le fucoïdane d’A. nodosum était un inhibiteur plus puissant que le fucoïdane de F. vesiculosus pour l’α-glucosidase avec des IC50 variant de 0,013 ~ 0,047 mg/ml, tout comme pour l’α-amylase avec des IC50 de 0,12 ~ 4,62 mg/mL selon le mois. Pour comprendre les facteurs clés expliquant les différences d’inhibition d’α-amylase entre les fucoïdane d’A. nodosum et F. vesiculosus, certaines caractéristiques structurales ont été analysées et comparées à du galactofucoidane qui a servi de contrôle. A partir des résultats obtenus, il est confirmé que la masse moléculaire plus faible (637 kDa) du fucoïdane d’A. nodosum et la présence de sulfates sont liées à son activité inhibitrice. Nous avons émis l’hypothèse que les faibles masses moléculaires permettent d’exposer facilement les groupements sulfate qui peuvent agir sur l’α-amylase par interaction électrostatique, et donc d'inhiber son activité. En conclusion, les algues brunes du Québec présentent un potentiel d’utilisation important pour leur valeur nutritionnelle et leurs composés bioactifs. Le fucoïdane a montré une activité d'inhibition des enzymes digestives de l'amidon (α-amylase et α-glucosidase) et cette activité est différente selon les espèces d'algues et la période de récolte. Une meilleure compréhension du mécanisme inhibiteur par le fucoïdane peut être utile afin de développer un ingrédient fonctionnel permettant de prévenir le diabète de Type-2.Fucus vesiculosus and Ascophyllum nodosum are edible brown seaweed and abundantly available in Quebec. However, they have been neglected because of their unknown value and technical limitation in harvest. In order to validate their usefulness, chemical composition in seaweeds and starch digestive enzyme inhibition activity by fucoidan extracted from two seaweed species were investigated with different seasons. The major components in both seaweeds were in order: polysaccharide > minerals > protein > fucoidan > lipid > phenol, and their quantity was quite variable depending on harvesting timing. F. vesiculosus contained larger amount of proteins and minerals, while A. nodosum had relatively more polysaccharides. Therefore, F. vesiculosus are advantageous as a nutritional source. Especially, from A. nodosum harvested in July, a fucoidan having higher purity and better yield was obtained. Fucoidans from two seaweeds species inhibited α-glucosidase activity while, only fucoidan from A. nodosum could inhibit α-amylase activity. A. nodosum fucoidan was a more potent inhibitor than F. vesiculosus fucoidan for α-glucosidase with IC50 of 0.013 ~ 0.047 mg/mL, and for α-amylase with IC50 of 0.12 ~ 4.62 mg/mL depending on harvest month. To understand the key factors explaining the difference in α-amylase inhibition between A. nodosum fucoidan and F. vesiculosus fucoidan, structural characteristic was analyzed and compared with galactofucoidan as a control. From the obtained results, it is confirmed that smaller molecular weight (637 kDa) of A. nodosum fucoidan and the presence of sulfates are related to its inhibitory activity. It is proposed that small molecular weight permits to expose easily sulfate groups for interaction with α-amylase throughout electrostatic interactions, and therefore inhibiting its activity. In conclusion, brown seaweeds in Quebec have a considerable importance for nutrition and bioactive products. Fucoidan shows the inhibition activity for starch digestive enzymes (α-amylase and α-glucosidase) and its activity is different depending on seaweed species and harvesting period. Further understanding of the inhibitory mechanism by fucoidan can be useful to develop a functional ingredient to help preventing for Type-2 diabetes

Adjacent Infrared Multitarget Detection Using Robust Background Estimation

Small target detection is very important for infrared search and track (IRST) problems. Grouped targets are difficult to detect using the conventional constant false alarm rate (CFAR) detection method. In this study, a novel multitarget detection method was developed to identify adjacent or closely spaced small infrared targets. The neighboring targets decrease the signal-to-clutter ratio in hysteresis threshold-based constant false alarm rate (H-CFAR) detection, which leads to poor detection performance in cluttered environments. The proposed adjacent target rejection-based robust background estimation can reduce the effects of the neighboring targets and enhance the small multitarget detection performance in infrared images by increasing the signal-to-clutter ratio. The experimental results of the synthetic and real adjacent target sequences showed that the proposed method produces an upgraded detection rate with the same false alarm rate compared to the recent target detection methods (H-CFAR, Top-hat, and TDLMS).111Ysciescopu

Clustering of Nodes in Layered-Tree Topology for Wireless Sensor Networks

Wireless sensor network is composed of a large number of sensor nodes of limited energy resource. The node clustering approach can improve the scalability and lifetime of wireless sensor network. In this paper we propose a novel node clustering protocol based on layered-tree topology for self-organizing distributed wireless sensor networks. It decides optimal number of clusters by employing a new approach for setting threshold value, including the probability of optimum number of cluster-heads and residual energy of the nodes. We also introduce a new scheme for layered-tree construction in each cluster. As a result, the proposed scheme can significantly improve the energy efficiency of the network and increase its lifetime. Computer simulation shows that the proposed scheme effectively reduces and balances the energy consumption of the nodes, and thus significantly extends the network lifetime compared to the existing schemes

Perception, Content and Conceptual Engagement: Is there any non-conceptual content?

This thesis aims to compensate for the defects in the forms of conceptualism which John McDowell (1994a) and Bill Brewer (1999) hold: it does this by analysing the conceptual structure of the content of experience using colour experience as the central case. First, the root of the debate between conceptualism and non-conceptualism, as I shall argue, is the different notions of concept and experience used by the two sides. The nonconceptualists’ notion of a concept, or conceptual capacity, has been defined very narrowly, satisfying very restricted conditions, whereas their notion of experience is much wider and more flexible, ranging from a subpersonal state to a personal level. By contrast, conceptualists are quite open to broad notions of a concept, or conceptual capacity, but seem to define the content of experience as belonging only to the personal level. Second, in order to build a bridge between these two different notions of both concept and experience respectively, I will argue that three major types of conceptual capacities can operate in experience. I call this ‘conceptual engagement’. I then suggest that we need to consider two perspectives on colour experience: namely, the functional and the expository. The former concerns ‘how experience physically works’, whereas the latter concerns “what experience has.” Both perspectives will prove useful for explaining perceptual content at the sub-personal and personal level. This distinction is required because what we call the ‘content’ of experience does not belong to just one particular stage of experience. Last, as a final supplementation of previous conceptualism, I will consider the discrimination abilities involved in perception as being themselves a type of conceptual capacity. At this point, I will adopt the notion of receptivity as used by McDowell (1994a), but deny that a conceptualist is committed to spontaneity being involved in receptivity. I will further propose that understanding discriminative abilities as perceptual receptivity could prepare the ground for taking over perceptual contents into the contents of thought. I will argue that perception could be passive and conceptual, hence separate from spontaneity

Symmetric negative differential resistance in a molecular nanosilver chain

The electrical transport properties of the molecular nanosilver chain have been investigated. We observed the symmetric negative differential resistance (NDR) in the current-voltage characteristics. The peak voltage (V P) increased but the peak current (I P) decreased upon cooling. The self-capacitance effect of the silver chain crystal is suggested to explain this unconventional NDR phenomenon.open0

Association between polymorphisms of arachidonate 12-lipoxygenase (ALOX12) and schizophrenia in a Korean population

Arachidonic acid (AA), an essential polyunsaturated fatty acid, is one of the major components of neural membranes, which show an altered phospholipid composition in schizophrenia. Arachidonate 12-lipoxygenase (ALOX12), an important enzyme, metabolizes AA to 12-HPETE, which affects catecholamine synthesis. However, research has yet to show the genetic association between ALOX12 and schizophrenia. Therefore, we investigated single nucleotide polymorphisms (SNP) of the ALOX12 gene in schizophrenia, recruiting patients with schizophrenia (n = 289) and normal controls (n = 306) from a Korean population. We selected three SNPs (rs1126667, rs434473, and rs1042357) of the ALOX12 gene and genotyped them by direct sequencing. We reviewed the schizophrenic patients' medical records and assessed them clinically using the Brief Psychiatric Rating Scale (BPRS), the Scale for the Assessment of Negative Symptoms (SANS), and the Operational Criteria Checklist (OPCRIT). Then we statistically analyzed the genetic associations between the SNPs and schizophrenia, finding a genetic association between both rs1126667 and rs1042357 and schizophrenia, in the recessive model (p = 0.015 and 0.015, respectively). We also found an association between rs434473 and negative symptoms, defined through a factor analysis of the OPCRIT data (p = 0.040). Consequently, we suggest that SNPs of the ALOX12 gene might be associated with schizophrenia and negative symptoms in this Korean population. These weak positives require additional study

Photothermal Polymer Nanocomposites of Tungsten Bronze Nanorods with Enhanced Tensile Elongation at Low Filler Contents

We present polymer nanocomposites of tungsten bronze nanorods (TBNRs) and ethylene propylene diene monomers (EPDM). The combination of these components allows the simultaneous enhancement in the mechanical and photothermal properties of the composites at low filler contents. The as-synthesized TBNRs had lengths and diameters of 14.0 +/- 2.4 nm and 2.5 +/- 0.5 nm, respectively, and were capped with oleylamine, which has a chemical structure similar to EPDM, making the TBNRs compatible with the bulk EPDM matrix. The TBNRs absorb a wide range of near-infrared light because of the sub-band transitions induced by alkali metal doping. Thus, the nanocomposites of TBNRs in EPDM showed enhanced photothermal properties owing to the light absorption and subsequent heat emission by the TBNRs. Noticeably, the nanocomposite with only 3 wt% TBNRs presented significantly enhanced tensile strain at break, in comparison with those of pristine EPDM, nanocomposites with 1 and 2 wt % TBNRs, and those with tungsten bronze nanoparticles, because of the alignment of the nanorods during tensile elongation. The photothermal and mechanical properties of these nanocomposites make them promising materials for various applications such as in fibers, foams, clothes with cold weather resistance, patches or mask-like films for efficient transdermal delivery upon heat generation, and photoresponsive surfaces for droplet transport by the thermocapillary effect in microfluidic devices and microengines