Fibronectin/phosphorylcholine coatings on fluorocarboned surfaces: a study upon adsorption and grafting processes

Depuis ces dernières décennies, le domaine des biomatériaux a connu un essor considérable, évoluant de simples prothèses aux dispositifs les plus complexes pouvant détenir une bioactivité spécifique. Outre, le progrès en science des matériaux et une meilleure compréhension des systèmes biologiques a offert la possibilité de créer des matériaux synthétiques pouvant moduler et stimuler une réponse biologique déterminée, tout en améliorant considérablement la performance clinique des biomatériaux. En ce qui concerne les dispositifs cardiovasculaires, divers recouvrements ont été développés et étudiés dans le but de modifier les propriétés de surface et d’améliorer l’efficacité clinique des tuteurs. En effet, lorsqu’un dispositif médical est implanté dans le corps humain, son succès clinique est fortement influencé par les premières interactions que sa surface établit avec les tissus et les fluides biologiques environnants. Le recouvrement à la surface de biomatériaux par diverses molécules ayant des propriétés complémentaires constitue une approche intéressante pour atteindre différentes cibles biologiques et orienter la réponse de l’hôte. De ce fait, l’élucidation de l’interaction entre les différentes molécules composant les recouvrements est pertinente pour prédire la conservation de leurs propriétés biologiques spécifiques. Dans ce travail, des recouvrements pour des applications cardiovasculaires ont été créés, composés de deux molécules ayant des propriétés biologiques complémentaires : la fibronectine (FN) afin de promouvoir l’endothélialisation et la phosphorylcholine (PRC) pour favoriser l’hémocompatibilité. Des techniques d’adsorption et de greffage ont été appliquées pour créer différents recouvrements de ces deux biomolécules sur un polymère fluorocarboné déposé par traitement plasma sur un substrat en acier inoxydable. Dans un premier temps, des films de polytétrafluoroéthylène (PTFE) ont été utilisés en tant que surface modèle afin d’explorer l’interaction de la PRC et de la FN avec les surfaces fluorocarbonées ainsi qu’avec des cellules endothéliales et du sang. La stabilité des recouvrements de FN sur l’acier inoxydable a été étudiée par déformation, mais également par des essais statiques et dynamiques sous-flux. Les recouvrements ont été caractérisés par Spectroscopie Photoéléctronique par Rayons X, immunomarquage, angle de contact, Microscopie Électronique de Balayage, Microscopie de Force Atomique et Spectrométrie de Masse à Ionisation Secondaire à Temps de Vol (imagerie et profilage en profondeur). Des tests d’hémocompatibilité ont été effectués et l’interaction des cellules endothéliales avec les recouvrements a également été évaluée. La FN greffée a présenté des recouvrements plus denses et homogènes alors que la PRC quant à elle, a montré une meilleure homogénéité lorsqu’elle était adsorbée. La caractérisation de la surface des échantillons contenant FN/PRC a été corrélée aux propriétés biologiques et les recouvrements pour lesquels la FN a été greffée suivie de l’adsorption de la PRC ont présenté les meilleurs résultats pour des applications cardiovasculaires : la promotion de l’endothélialisation et des propriétés d’hémocompatibilité. Concernant les tests de stabilité, les recouvrements de FN greffée ont présenté une plus grande stabilité et densité que dans le cas de l’adsorption. En effet, la pertinence de présenter des investigations des essais sous-flux versus des essais statiques ainsi que la comparaison des différentes stratégies pour créer des recouvrements a été mis en évidence. D’autres expériences sont nécessaires pour étudier la stabilité des recouvrements de PRC et de mieux prédire son interaction avec des tissus in vivo.

How can geographical information systems and spatial analysis inform a response to prescription opioid misuse? a discussion in the context of existing literature

Effect of soil structure on temporal and spatial dynamics of bacteria

Soil is a complex heterogeneous system comprising of highly variable and dynamic micro-habitats that have significant impacts on the growth and activity of resident microbiota. A question addressed in this research is how soil structure affects the temporal dynamics and spatial distribution of bacteria. Using repacked microcosms, the effect of bulk-density, aggregate sizes and water content on growth and distribution of introduced Pseudomonas fluorescens and Bacillus subtilis bacteria was determined. Soil bulk-density and aggregate sizes were altered to manipulate the characteristics of the pore volume where bacteria reside and through which distribution of solutes and nutrients is controlled. X-ray CT was used to characterise the pore geometry of repacked soil microcosms. Soil porosity, connectivity and soil-pore interface area declined with increasing bulk-density. In samples that differ in pore geometry, its effect on growth and extent of spread of introduced bacteria was investigated. The growth rate of bacteria reduced with increasing bulk-density, consistent with a significant difference in pore geometry. To measure the ability of bacteria to spread thorough soil, placement experiments were developed. Bacteria were capable of spreading several cm’s through soil. The extent of spread of bacteria was faster and further in soil with larger and better connected pore volumes. To study the spatial distribution in detail, a methodology was developed where a combination of X-ray microtopography, to characterize the soil structure, and fluorescence microscopy, to visualize and quantify bacteria in soil sections was used. The influence of pore characteristics on distribution of bacteria was analysed at macro- and microscales. Soil porosity, connectivity and soil-pore interface influenced bacterial distribution only at the macroscale. The method developed was applied to investigate the effect of soil pore characteristics on the extent of spread of bacteria introduced locally towards a C source in soil. Soil-pore interface influenced spread of bacteria and colonization, therefore higher bacterial densities were found in soil with higher pore volumes. Therefore the results in this showed that pore geometry affects the growth and spread of bacteria in soil. The method developed showed showed how thin sectioning technique can be combined with 3D X-ray CT to visualize bacterial colonization of a 3D pore volume. This novel combination of methods is a significant step towards a full mechanistic understanding of microbial dynamics in structured soils.

Incoherent solitons and condensation processes

We show that coherent phase effects may play a relevant role in the nonlinear propagation of partially incoherent waves, which lead to unexpected processes of condensation, or incoherent soliton generation in instantaneous response nonlinear media. © 2005 OSA.

Study of the ecophysiological stress effects on HPG and HPI axes, immunity system and reproduction processes in Persian sturgeon (Acipenser persicus)

The ecophysiological effects of stress in female Persian sturgeon, Acipenser persicus brood fishes during catch, transport and their confinement in the Kurenski ponds at the Shahid Dr. Beheshti Fish Propagation and Rearing Center were studied. The brood fishes under study were caught at three catch stations located at the Sefidrud River, Sefidrud River estuary and Gorganrud River estuary and were held in ponds at the Shahid Marjani Fish Propagation and Rearing Center.

Interactions between Late Quaternary volcanic and sedimentary processes in the Naples Bay, Southern Tyrrhenian sea

The interactions between Late Quaternary volcanic and sedimentary processes in the Naples Bay, Southern Tyrrhenian sea, are here discussed through the results of the marine geological survey at the scale 1:25.000. The example of the geological map n. 465 “Isola di Procida”, herein presented, has put in evidence the stratigraphy of marine Quaternary deposits and related volcanic seismic units. The volcanic deposits cropping out in the Procida island have been explained as the result of eruptions of local eruptive centres. The geological survey carried out onshore indicates the occurrence of several pyroclastic units linked to the eruptive activity of the Ischian and Phlegrean volcanic complexes, interstratified with the products erupted by local volcanic centres. The occurrence in the pyroclastic sequences of Ischia and Procida islands of several marker horizons and their stratigraphic correlations have allowed to reconstruct the volcanological evolution of the two islands and the interactions with sedimentary processes at the scale of the whole Tyrrhenian margin. Four geological maps at the scale 1:25.000 covering the whole Naples Bay have been reconstructed based on the interpretation of marine geological and geophysical data. The stratigraphic relationships between the seismic units and the eruptive deposits have testified the activity of several monogenetic volcanic centers, whose products are interstratified with marine and continental deposits of the Late Quaternary depositional sequence.

Continuum tensor network field states, path integral representations and spatial symmetries

A natural way to generalize tensor network variational classes to quantum field systems is via a continuous tensor contraction. This approach is first illustrated for the class of quantum field states known as continuous matrix-product states (cMPS). As a simple example of the path-integral representation we show that the state of a dynamically evolving quantum field admits a natural representation as a cMPS. A completeness argument is also provided that shows that all states in Fock space admit a cMPS representation when the number of variational parameters tends to infinity. Beyond this, we obtain a well-behaved field limit of projected entangled-pair states (PEPS) in two dimensions that provide an abstract class of quantum field states with natural symmetries. We demonstrate how symmetries of the physical field state are encoded within the dynamics of an auxiliary field system of one dimension less. In particular, the imposition of Euclidean symmetries on the physical system requires that the auxiliary system involved in the class' definition must be Lorentz-invariant. The physical field states automatically inherit entropy area laws from the PEPS class, and are fully described by the dissipative dynamics of a lower dimensional virtual field system. Our results lie at the intersection many-body physics, quantum field theory and quantum information theory, and facilitate future exchanges of ideas and insights between these disciplines.

Computational modelling of reduction and smelting processes in the primary metals industries

Abstract not available

Submarine landform assemblages and sedimentary processes related to glacier surging in Kongsfjorden, Svalbard

High-resolution swath-bathymetry data from inner Kongsfjorden, Svalbard, reveal characteristic landform assemblages formed during and after surges of tidewater glaciers, and provide new insights into the dynamics of surging glaciers. Glacier front oscillations and overriding related to surge activity lead to the formation of overridden moraines, glacial lineations of two types, terminal moraines, associated debris lobes and De Geer moraines. In contrast to submarine landform assemblages from other Svalbard fjords, the occurrence of two kinds of glacial lineations and the presence of De Geer moraines suggest variability in the landforms produced by surge-type tidewater glaciers. All the landforms in inner Kongsfjorden were deposited during the last c. 150 years. Lithological and acoustic data from the innermost fjord reveal that suspension settling from meltwater plumes as well as ice rafting are dominant sedimentary processes in the fjord, leading to the deposition of stratified glacimarine muds with variable numbers of clasts. Reworking of sediments by glacier surging results in the deposition of sediment lobes containing massive glacimarine muds. Two sediment cores reveal minimum sediment accumulation rates related to the Kongsvegen surge from 1948; these were 30 cm a-1 approximately 2.5 km beyond the glacier front shortly after surge termination, and rapidly dropped to an average rate of 1.8 cm a-1 in ∼1950, during glacier retreat.

Temporal and spatial variation in temperature experienced by macrofauna at main endeavour Hydrothermal vent field

A significant focus of hydrothermal vent ecological studies has been to understand how species cope with various stressors through physiological tolerance and biochemical resistance. Yet, the environmental conditions experienced by vent species have not been well characterized. This objective requires continuous observations over time intervals that can capture environmental variability at scales that are relevant to animals. We used autonomous temperature logger arrays (four roughly parallel linear arrays of 12 loggers spaced every 10–12 cm) to study spatial and temporal variations in the thermal regime experienced by hydrothermal vent macrofauna at a diffuse flow vent. Hourly temperatures were recorded over eight months from 2010 to 2011 at Grotto vent in the Main Endeavour vent field on the Juan de Fuca Ridge, a focus area of the Ocean Networks Canada cabled observatory. The conspicuous animal assemblages in video footage contained Ridgeia piscesae tubeworms, gastropods (primarily Lepetodrilus fucensis), and polychaetes (polynoid scaleworms and the palm worm Paralvinella palmiformis). Two dimensional spatial gradients in temperature were generally stable over the deployment period. The average temperature recorded by all arrays, and in some individual loggers, revealed distinctive fluctuations in temperature that often corresponded with the tidal cycle. We postulate that this may be related to changes in bottom currents or fluctuations in vent discharge. A marked transient temperature increase lasting over a period of days was observed in April 2011. While the distributions and behavior of Juan de Fuca Ridge vent invertebrates may be partially constrained by environmental temperature and temperature tolerance, except for the one transient high-temperature event, observed fluid temperatures were generally similar to the thermal preferences for some species, and typically well below lethal temperatures for all species. Average temperatures of the four arrays ranged from 4.1 to 11.0 °C during the deployment, indicating that on an hourly timescale the temperature conditions in this tubeworm community were fairly moderate and stable. The generality of these findings and behavioural responses of vent organisms to predictable rhythmicity and non-periodic temperature shifts are areas for further investigation

Determination of biodiversity and spatial and temporal distribution pattern of demersal fishes in the Oman Sea

In this project, have been studied to determine the appropriate model to spatial, temporal and diversity of demersal fishes in the Sea of Oman, including Trichiuridae, Nemipteridae, Haemulidae, Arridae, Synodontidae, Batoidfishes, Carangidae, Scianidae, Carchariniformes and Serranidae. This research became operational from catch data during 2003 to 2013 (in 2007, due to the lack of ship failed). Processing and calculations was evaluated by using the software Excel, SPSS, Arc GIS and table curve 3D highest biomass and abundance was showed in strata A and C and 10-30 m depth layers was showed the best condition biomass. In other words, highest biomass was showed in the eastern region in the Oman Sea than the central and western regions. Batoidfishes and Trichiuridae had the highest biomass .Depth factors was showed a significant correlation with the biomass. Scianidae, Serranidae and Haemulidae were showed a large decline. Synodontidae was showed a very large increase. The largest of Shannon index belong to central and western region of the Oman Sea. The highest Shannon index was showed 10-20 and 50-100 m, respectively. The Distribution maps based on the biomass was analyzed by using Arc GIS software. So that were identified in the first time in a ten-year period and carefully catch stations any economic of aquatic group. In conclusion, the depth can be found in the pattern of distribution, abundance and diversity of fish from away the beach so that follow specific pattern.

Study of the development and evolution of seasonal thermocline and turbulent processes in the northern parts of Persian Gulf using numerical modeling

The Persian Gulf (PG) is a semi-enclosed shallow sea which is connected to open ocean through the Strait of Hormuz. Thermocline as a suddenly decrease of temperature in subsurface layer in water column leading to stratification happens in the PG seasonally. The forcing comprise tide, river inflow, solar radiation, evaporation, northwesterly wind and water exchange with the Oman Sea that influence on this process. In this research, analysis of the field data and a numerical (Princeton Ocean Model, POM) study on the summer thermocline development in the PG are presented. The Mt. Mitchell cruise 1992 salinity and temperature observations show that the thermocline is effectively removed due to strong wind mixing and lower solar radiation in winter but is gradually formed and developed during spring and summer; in fact as a result of an increase in vertical convection through the water in winter, vertical gradient of temperature is decreased and thermocline is effectively removed. Thermocline development that evolves from east to west is studied using numerical simulation and some existing observations. Results show that as the northwesterly wind in winter, at summer transition period, weakens the fresher inflow from Oman Sea, solar radiation increases in this time interval; such these factors have been caused the thermocline to be formed and developed from winter to summer even over the northwestern part of the PG. The model results show that for the more realistic monthly averaged wind experiments the thermocline develops as is indicated by summer observations. The formation of thermocline also seems to decrease the dissolved oxygen in water column due to lack of mixing as a result of induced stratification. Over most of PG the temperature difference between surface and subsurface increases exponentially from March until May. Similar variations for salinity differences are also predicted, although with smaller values than observed. Indeed thermocline development happens more rapidly in the Persian Gulf from spring to summer. Vertical difference of temperature increases to 9 centigrade degrees in some parts of the case study zone from surface to bottom in summer. Correlation coefficients of temperature and salinity between the model results and measurements have been obtained 0.85 and 0.8 respectively. The rate of thermcline development was found to be between 0.1 to 0.2 meter per day in the Persian Gulf during the 6 months from winter to early summer. Also it is resulted from the used model that turbulence kinetic energy increases in the northwestern part of the PG from winter to early summer that could be due to increase in internal waves activities and stability intensified through water column during this time.

Transfer function-noise modeling and spatial interpolation to evaluate the risk of extreme (shallow) water-table levels in the Brazilian Cerrados

Water regimes in the Brazilian Cerrados are sensitive to climatological disturbances and human intervention. The risk that critical water-table levels are exceeded over long periods of time can be estimated by applying stochastic methods in modeling the dynamic relationship between water levels and driving forces such as precipitation and evapotranspiration. In this study, a transfer function-noise model, the so called PIRFICT-model, is applied to estimate the dynamic relationship between water-table depth and precipitation surplus/deficit in a watershed with a groundwater monitoring scheme in the Brazilian Cerrados. Critical limits were defined for a period in the Cerrados agricultural calendar, the end of the rainy season, when extremely shallow levels (< 0.5-m depth) can pose a risk to plant health and machinery before harvesting. By simulating time-series models, the risk of exceeding critical thresholds during a continuous period of time (e.g. 10 days) is described by probability levels. These simulated probabilities were interpolated spatially using universal kriging, incorporating information related to the drainage basin from a digital elevation model. The resulting map reduced model uncertainty. Three areas were defined as presenting potential risk at the end of the rainy season. These areas deserve attention with respect to water-management and land-use planning.

Coarse-graining and renormalisation group methods for the elucidation of the kinetics of complex nucleation and growth processes

We review our work on generalisations of the Becker-Doring model of cluster-formation as applied to nucleation theory, polymer growth kinetics, and the formation of upramolecular structures in colloidal chemistry. One valuable tool in analysing mathematical models of these systems has been the coarse-graining approximation which enables macroscopic models for observable quantities to be derived from microscopic ones. This permits assumptions about the detailed molecular mechanisms to be tested, and their influence on the large-scale kinetics of surfactant self-assembly to be elucidated. We also summarise our more recent results on Becker-Doring systems, notably demonstrating that cross-inhibition and autocatalysis can destabilise a uniform solution and lead to a competitive environment in which some species flourish at the expense of others, phenomena relevant in models of the origins of life.

Transportation and spatial development : an overview and a future direction