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.     

The molecular basis for A-site mutations conferring aminoglycoside resistance: relationship between ribosomal susceptibility and X-ray crystal structures

Aminoglycoside antibiotics target the 16S ribosomal RNA (rRNA) bacterial A site and induce misreading of the genetic code. Point mutations of the ribosomal A site may confer resistance to aminoglycoside antibiotics. The influence of bacterial mutations (introduced by site-directed mutagenesis) on ribosomal drug susceptibility was investigated in vivo by determination of minimal inhibitory concentrations. To determine the origin of the various resistance phenotypes at a molecular level, the in vivo results were compared with the previously published crystal structures of paromomycin, tobramycin, and geneticin bound to oligonucleotides containing the minimal A site. Two regions appear crucial for binding in the A site: the single adenine residue at position 1408 and the non-Watson-Crick U1406.U1495 pair. The effects of mutations at those positions are modulated by the nature of the substituent at position 6' (either hydroxy or ammonium group) on ring I, by the number of positive charges on the antibiotic, and by the linkage between rings I and III (either 4,5 or 4,6). In particular, the analysis demonstrates: 1) that the C1409-G1491 to A1409-U1491 polymorphism (observed in 15 % of bacteria) is not associated with resistance, which indicates that it does not affect the stacking of ring I on residue 1491, 2) that the high-level resistance to 6'-NH3+ aminoglycosides exhibited by the A1408G mutation most probably results from the inability of ring I forming a pseudo base pair with G1408, which prevents its insertion inside the A site helix, and 3) that mutations of the uracil residues forming the U1406.U1495 pair either to cytosine or to adenine residues mostly confer low to moderate levels of drug resistance, whereas the U1406C/U1495A double mutation confers high-level resistance (except for neomycin), which suggests that aminoglycoside binding to the wild-type A site and its functional consequences strongly depend on a particular geometry of the U1406.U1495 pair. The relationships between the resistance phenotypes observed in vivo and the interactions described at the molecular level define the biological importance of the different structural interactions observed by X-ray crystallography studies.     

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.     

High energy resolution five-crystal spectrometer for high quality fluorescence and absorption measurements on an x-ray absorption spectroscopy beamline

Fluorescence detection is classically achieved with a solid state detector (SSD) on x-ray absorption spectroscopy (XAS) beamlines. This kind of detection however presents some limitations related to the limited energy resolution and saturation. Crystal analyzer spectrometers (CAS) based on a Johann-type geometry have been developed to overcome these limitations. We have tested and installed such a system on the BM30B/CRG-FAME XAS beamline at the ESRF dedicated to the structural investigation of very dilute systems in environmental, material and biological sciences. The spectrometer has been designed to be a mobile device for easy integration in multi-purpose hard x-ray synchrotron beamlines or even with a laboratory x-ray source. The CAS allows to collect x-ray photons from a large solid angle with five spherically bent crystals. It will cover a large energy range allowing to probe fluorescence lines characteristic of all the elements from Ca (Z = 20) to U (Z = 92). It provides an energy resolution of 1-2 eV. XAS spectroscopy is the main application of this device even if other spectroscopic techniques (RIXS, XES, XRS, etc.) can be also achieved with it. The performances of the CAS are illustrated by two experiments that are difficult or impossible to perform with SSD and the complementarity of the CAS vs SSD detectors is discussed.     

Terthiophene-cyanovinylene π-conjugated polymers as donor material for organic solar cells

Conjugated polymers of hybrid structure containing cyanovinylene linkages have been synthesized by Knoevenagel condensation of diformyl terthienyls with para-dicyanomethylbenzene. UV–vis and cyclic voltammetric data show that these polymers combine reduced band gap, improved light-harvesting properties and low lying HOMO level. Whereas the very low solubility of the polymers did not allow the fabrication of bulk heterojunction solar cells, bilayer heterojunction solar cells have been realized using thermally evaporated films of fullerene C₆₀ as acceptor material. The best devices show a maximum external quantum efficiency of ～20% and a power conversion efficiency of 0.40% under simulated AM 1.5 solar illumination.     

The effect of zirconia substitution on the high-temperature transformation of the monoclinic-prime phase in yttrium tantalate

Amorphous yttrium tantalate, as well as solid solutions containing zirconia, transform on heating to a monoclinic-prime phase and then, with further heating, to a crystalline tetragonal (T) solid solution phase at ～1450?°C. On subsequent cooling the tetragonal phase converts by a second-order displacive transformation to a different monoclinic phase not to the monoclinic-prime phase. On subsequent reheating and cooling, the phase transformation occurs between the monoclinic (M) and tetragonal phases, and the monoclinic-prime phase cannot be recovered. The limit of zirconia solubility in both the monoclinic-prime and monoclinic phases lies between 25 and 28?m/o ZrO₂, consistent with previous first-principles calculations. The monoclinic-prime phase is stable up to at least 1400?°C for 100?h for zirconia concentrations from 0 to ～60?m/o ZrO₂. This temperature exceeds the temperature of the equilibrium M-T phase transformation suggesting that the monoclinic-prime phase transforms directly to the tetragonal phase by a reconstructive transformation and is unaffected by the zirconia in solid solution.