Evaluation of Elastin-Fibrin biomaterial in experimental pancreatic surgery

Artificial connective soft tissue, so-called Elastin-Fibrin biomaterial, was investigated to reinforce a pancreato-jejunum anastomosis in the dog. The ambiguous results invite us, however, to improve the quality of the material, especially against proteolytic degradation: elastinolysis and fibrinolysis. Antibiotic was also added. The improved material was tested, first in rabbit then in dog, to repair a large loss of substance in the duodenum, just in front of the Wirsung duct. In view of the successful results, we are now attempting an evaluation in humans, for all indications throughout the digestive system.     

Unclogging improvement based on interdate and interreach comparison of water release monitoring (Durance,France)

Large‐scale flow release experiments are becoming common for improving aquatic habitat quality downstream of dams. Because of the naturally high fine sediment load in the Durance River, France due to inputs from torrential tributaries draining badlands, unpredictable high flow events with dam overspill are not always sufficient to prevent clogging, which can lead to habitat degradation (especially spawning habitats) in bypassed reaches. Therefore, large‐scale flow experiments were conducted on four reaches to test the efficacy of clear‐water releases to improve aquatic habitat conditions. Continuous measurements of water depth, suspended sediment concentrations, and turbidity were conducted during twelve releases and compared on nine. Before and after each release, superficial clogging was measured. The study shows that there is a link between the volume of suspended sediments carried by water releases and the initial clogging. The volumes carried were low compared with the river's annual transport. The effect on clogging can vary significantly from one release to another. In particular, the hydrological context surrounding the releases has a significant influence on clogging. Comparisons of monitoring showed that releases are more effective on reaches that are more severely regulated (high hydrological control) than on those that are less well‐controlled. The areas with the highest initial clogging tend to unclog more than those with lower initial clogging; however, the latter zones are most impacted by ineffective releases. Performing a release on environments with low initial clogging can therefore be environmentally damaging. To ensure that releases are successful and that intervention is warranted, initial clogging should be measured in the field and releases should only be performed if the clogging is judged to be unfavourable.     

Fair multi-agent task allocation for large datasets analysis

MapReduce is a design pattern for processing large datasets distributed on a cluster. Its performances are linked to the data structure and the runtime environment. Indeed, data skew can yield an unfair task allocation, but even when the initial allocation produced by the partition function is well balanced, an unfair allocation can occur during the reduce phase due to the heterogeneous performance of nodes. For these reasons, we propose an adaptive multi-agent system. In our approach, the reducer agents interact during the job and the task reallocation is based on negotiation in order to decrease the workload of the most loaded reducer and so the runtime. In this paper, we propose and evaluate two negotiation strategies. Finally, we experiment our multi-agent system with real-world datasets over heterogeneous runtime environment.     

Piezoresistive encoders for ratcheting actuation systems

This paper introduces piezoresistive encoders that can provide information on the performance of ratcheting actuation systems, and may be useful in future applications that require position determination. One unique feature of the encoders is that they gain their piezoresistance from the bulk properties of polycrystalline silicon without additional fabrication steps. In this study, two encoders are considered: a parallel-guiding encoder in an on-chip Wheatstone bridge, and a piezoresistive microdisplacement transducer (PMT) encoder in an on-chip Wheatstone bridge. In tests, the encoders each generated measurable signals, with the PMT encoder providing the best sensitivity. The PMT encoder operated at actuation frequencies up to 920 Hz and produced a signal between 2 V and 3.2 V (applied gain of 1000). The PMT encoder produced unique signals corresponding to distinct ideal and non-ideal behaviors of a ratchet wheel actuation system.     

Effect of the Cold-Sprayed Aluminum Coating-Substrate Interface Morphology on Bond Strength for Aircraft Repair Application

This article is dealing with the effects of surface preparation of the substrate on aluminum cold-sprayed coating bond strength. Different sets of AA2024-T3 specimens have been coated with pure Al 1050 feedstock powder, using a conventional cold spray coating technique. The sets were grit-blasted (GB) before coating. The study focuses on substrate surface topography evolution before coating and coating-substrate interface morphology after coating. To study coating adhesion by LASAT^® technique for each set, specimens with and without preceding GB treatment were tested in load-controlled conditions. Then, several techniques were used to evaluate the effects of substrate surface treatment on the final coating mechanical properties. Irregularities induced by the GB treatment modify significantly the interface morphology. Results showed that particle anchoring was improved dramatically by the presence of craters. The substrate surface was characterized by numerous anchors. Numerical simulation results exhibited the increasing deformation of particle onto the grit-blasted surface. In addition, results showed a strong relationship between the coating-substrate bond strength on the deposited material and surface preparation.     

Argon Attenuates Multiorgan Failure in Relation with HMGB1 Inhibition

Argon inhalation attenuates multiorgan failure (MOF) after experimental ischemic injury. We hypothesized that this protection could involve decreased High Mobility Group Box 1 (HMGB1) systemic release. We investigated this issue in an animal model of MOF induced by aortic cross-clamping. Anesthetized rabbits were submitted to supra-coeliac aortic cross-clamping for 30 min, followed by 300 min of reperfusion. They were randomly divided into three groups (n = 7/group). The Control group inhaled nitrogen (70%) and oxygen (30%). The Argon group was exposed to a mixture of argon (70%) and oxygen (30%). The last group inhaled nitrogen/oxygen (70/30%) with an administration of the HMGB1 inhibitor glycyrrhizin (4 mg/kg i.v.) 5 min before aortic unclamping. At the end of follow-up, cardiac output was significantly higher in Argon and Glycyrrhizin vs. Control (60 ± 4 and 49 ± 4 vs. 33 ± 8 mL/kg/min, respectively). Metabolic acidosis was attenuated in Argon and Glycyrrhizin vs. Control, along with reduced amount of norepinephrine to reverse arterial hypotension. This was associated with reduced interleukin-6 and HMGB1 plasma concentration in Argon and Glycyrrhizin vs. Control. End-organ damages were also attenuated in the liver and kidney in Argon and Glycyrrhizin vs. Control, respectively. Argon inhalation reduced HMGB1 blood level after experimental aortic cross-clamping and provided similar benefits to direct HMGB1 inhibition.     

Biological Relevance of RGD-Integrin Subtype-Specific Ligands in Cancer

Integrins are heterodimeric transmembrane proteins able to connect cells with the micro-environment. They represent a family of receptors involved in almost all the hallmarks of cancer. Integrins recognizing the Arg-Gly-Asp (RGD) peptide in their natural extracellular matrix ligands have been particularly investigated as tumoral therapeutic targets. In the last 30 years, intense research has been dedicated to designing specific RGD-like ligands able to discriminate selectively the different RGD-recognizing integrins. Chemists′ efforts have led to the proposition of modified peptide or peptidomimetic libraries to be used for tumor targeting and/or tumor imaging. Here we review, from the biological point of view, the rationale underlying the need to clearly delineate each RGD-integrin subtype by selective tools. We describe the complex roles of RGD-integrins (mainly the most studied αvβ3 and α5β1 integrins) in tumors, the steps towards selective ligands and the current usefulness of such ligands. Although the impact of integrins in cancer is well acknowledged, the biological characteristics of each integrin subtype in a specific tumor are far from being completely resolved. Selective ligands might help us to reconsider integrins as therapeutic targets in specific clinical settings.     

Oxidation of Ingested Phenolics in the Tree-Feeding Caterpillar <Emphasis Type="Italic">Orgyia leucostigma</Emphasis> Depends on Foliar Chemical Composition

Tannins are believed to function as antiherbivore defenses, in part, by acting as prooxidants. However, at the high pH found in the midguts of caterpillars, the oxidative activities of different types of tannins vary tremendously: ellagitannins > galloyl glucoses > condensed tannins. Ingested ascorbate is utilized by caterpillars to minimize phenolic oxidation in the midgut. Thus, leaves that contain higher levels of reactive tannins and lower levels of ascorbate were hypothesized to produce higher levels of phenolic oxidation in caterpillars. We tested this hypothesis with eight species of deciduous trees by measuring their foliar phenolic and ascorbate compositions and measuring the semiquinone radical (oxidized phenolic) levels formed in caterpillars that ingested each species. When the generalist caterpillars of Orgyia leucostigma (Lymantriidae) fed on the leaves of tree species in which condensed tannins were predominant (i.e., Populus tremuloides, P. deltoides, and Ostrya virginiana), semiquinone radical levels were low or entirely absent from the midgut contents. In contrast, species that contained higher levels of ellagitannins (or galloyl rhamnoses; i.e., Quercus alba, Acer rubrum, and A. saccharum) produced the highest levels of semiquinone radicals in O. leucostigma. Low molecular weight phenolics contributed relatively little to the overall oxidative activities of tree leaves compared with reactive tannins. Ascorbate levels were lowest in the species that also contained the highest levels of oxidatively active tannins, potentially exacerbating phenolic oxidation in the gut lumen. We conclude that the tannin compositions of tree leaves largely determine the effectiveness of foliar phenolics as oxidative defenses against caterpillars such as O. leucostigma.     

Real-Time Aerosol Density Determination Utilizing a Modified Scanning Mobility Particle Sizer—Aerosol Particle Mass Analyzer System

Real time secondary organic aerosol (SOA) density evolution for m-xylene photo-oxidation and α-pinene ozonolysis was obtained using an Aerosol Particle Mass Analyzer (APM)/Scanning Mobility Particle Spectrometer (SMPS) setup, which has been modified to achieve higher transmission of particles and improved sampling frequency. The aerosol density of SOA generated from α-pinene ozonolysis was found to be 1.24 ± 0.03 g/cm³ while the aerosol generated from m-xylene photo-oxidation was determined to be 1.35 ± 0.03 g/cm³. These results confirm the measurement approach from a combined SMPS and Aerodyne Aerosol Mass Spectrometer (AMS) system and are found to be within good agreement with the effective density measurements.     

Laser machining of GaN-on-diamond wafers

The commercialization of gallium-nitride microwave circuits on diamond substrates requires chip-dicing technology and via formation process compatible with standard semiconductor processes. This paper discusses issues related to dicing and drilling of GaN-on-diamond wafers for RF power transistor applications (die size < 1 mm²) using laser micromachining.