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As part of the evaluation of the French plan for the elimination of measles and rubella, we conducted a seroprevalence survey in 2013, aimed at updating seroprevalence data for people 18–32 years old. A secondary objective was to estimate measles incidence in this population during the 2009–2011 outbreak, and thus estimate the exhaustiveness of measles mandatory reporting. We used a cross-sectional survey design, targeting blood donors 18–32 years old, living in France since 2009, who came to give blood in a blood collecting site. We included 4647 people in metropolitan France, 806 people in Réunion Island and 496 in the French Caribbean. A further 3942 individuals were interviewed in the south-east region of metropolitan France to estimate the exhaustiveness of measles mandatory reporting. One of the main findings of this survey is that the proportion of people 18–32 years old susceptible to both measles and rubella infections remained high in France in 2013, 9.2% and 5.4%, respectively, in metropolitan France, even after the promotion campaigns about vaccination catch-up during and following the major measles epidemic in 2009–2011. Applying our results to French census data would suggest that around 1 million people aged 18–32 years old are currently susceptible to measles in France, despite this age group being one of the vaccination targets of the national measles elimination plan. Another important finding is that only an estimated 45% of the true number of cases in this age group was actually notified, despite notification being mandatory.
The wheat dwarf disease is among the most damaging diseases in cereals. Its aetiological agent is the Wheat dwarf virus (WDV), which is exclusively transmitted from plant to plant by leafhoppers from the genus Psammotettix (Hemiptera, Cicadellidae). The parameters linked to the WDV/Psammotettix pathosystem are still poorly understood. We studied Psammotettix individuals collected in wheat and barley fields in France and, as a comparison, from grassland at agroecological interface in West Slovenia. Species identity of males and females has been determined using multiple criteria. In the first step, the characterization of the collected individuals included recordings of vibrational signals used in mating behaviour and morphometric analyses. In addition, a 442 nt sequence of the mitochondrial cytochrome oxydase I (COI) gene was obtained for some individuals and compared to COI sequences of the Psammotettix leafhoppers available in public databases. In the cereal fields in France, Psammotettix alienus was the most numerous species; however, it sometimes occurred together with Psammotettix confinis, while in the grasslands in Slovenia, the third syntopic species in Psammotettix community was Psammotettix helvolus. The temporal parameters of the P. alienus male calling song that were measured in this study were very similar to those measured in a previous study. The local biotic and/or abiotic parameters most likely influence the life history of Psammotettix leafhoppers, and the proportion of viruliferous individuals collected in cereal fields was 14.9%, while leafhoppers collected in Slovenia were virus-free. Taken together, results show that more detailed information on population structure of Psammotettix leafhoppers is crucial for providing an insight into the epidemiology of wheat dwarf disease.
Firstly, a brief overview will be given on different models that are able to describe the behaviour of wave propagation as a function of specific frequency ranges. Each range corresponds to different heating systems, namely, 20–100 MHz for the ion cyclotron resonant heating, 2–20 GHz for lower-hybrid heating or current drive, and 100–250 GHz for electron cyclotron resonant heating or current drive systems. The specification of every system will be explained in detail, including the typical set of equations and the assumptions needed to describe the properties of these heating or current drive systems, as well as their specific domains of validity. In these descriptions, special attention will be paid to the boundary conditions. A review of specific physical problems associated with the wave heating systems will also be provided. The review will detail the role of simulation in answering questions that arise from experiments on magnetized plasma devices devoted to fusion. A few examples that will be covered are the impact of edge turbulence on wave propagation and its consequences on heating system performance, the effects of fast particles and ponderomotive effects, among others. A study that is more focused on radio-frequency sheath effects will also be discussed. It shows that such simulations require very sophisticated tools to gain a partial understanding of the observations undertaken in dedicated experiments. To conclude this review, an overview will be given about the requirements and progress necessary to obtain relevant predictive simulation tools able to describe the wave heating systems used in fusion devices.
Dairy cow systems based on grassland utilization are characterized by a variation of harvested forage quality from 1 year to another and a fluctuation of grass availability and quality during the pasture season. Consequently, the energy supplied by the diet – i.e., concentrates plus hay or silage in winter and grazing in summer, may not always match animal requirements. A modelling approach enables a representation of the complex relationships between the cow and pasture as they interact. A dynamic model of intake and milk production, focused on grassland utilization by the dairy cow, has been developed. The model operates in a deterministic fashion with a daily time step and is capable of dealing with a day-to-day variation in grass availability and quality at grazing as well as a constant feeding regime during the winter. The model has been built based on the theory that milk production is a result of (i) the energy requirements defined by the potential milk production and physiological status of dairy cows; (ii) the variation of energy supply by the diet; (iii) the ability of dairy cows to mobilize or store body reserves. The model was validated by comparing milk production predictions with experimental data (two groups of dairy cows in the winter time and one group at grazing). The model demonstrates a satisfactory range of accuracy (root-mean-square deviation equal to 1·8, 2·1 and 1·4 kg/cow/day). Model validations indicate that milk production predictions are sensitive to the diet offered (forage, grass and concentrate supply) and depend on dairy cow characteristics and their requirements (pMP). This model can be connected to a grass growth model in order to develop whole farm simulations.
Depending on their application temperature thermoelectric (TE) materials are classified in three main categories; as low (up to 250°C), intermediate (up to 550°C) and high (above 600°C) temperature. Currently, Skutterudites (CoSb3) based materials have shown promising results in the intermediate temperature range (300-500°C). This family of material is highly suitable for automotive, marine transportation and industrial power generation applications to recover the waste heat from the exhaust and generate electricity. Conventional TE modules need p- and n-type semiconductor materials and for the skutterudite family, iron (Fe) has proven to be among the best candidates for the substitution of cobalt sites. Additionally, rare earths are introduced as rattlers in the crystal cages of the skutterudite to decrease the thermal conductivity, thus improving the figure of merit ZT of the TE material. For practical application for device fabrication, stability of these materials is of great importance. Compositional stability is being addressed as the material decomposes above certain temperature. Temperature dependent x-ray diffraction study was performed on Fe substituted, Yb-filled skutterudites, using Beam Line I711 at MAX LAB, to observe the crystal structure as a function of temperature. Diffraction patterns were collected from room temperature up to 500°C by utilizing Huber furnace. The results show success in filling process showing almost 80% reduction of the thermal conductivity from bulk. Additionally the thermal expansion coefficient value was within the average value for skutterudites which proves practical application of this powder for industrial applications.
Latest nanotechnology concepts applied in thermoelectric (TE) research have opened many new avenues to improve the ZT value. Low dimensional structures can improve the ZT value as compared to bulk materials by substantial reduction in the lattice thermal conductivity, κL. However, the materials were not feasible for the industrial scale production of macroscopic devices because of complicated and costly manufacturing processes involved. Bulk nanostructured (NS) TEs are normally fabricated using a bulk process rather than a nano-fabrication process, which has the important advantage of producing in large quantities and in a form that is compatible with commercially available TE devices.
We developed fabrication strategies for bulk nanostructured skutterudite materials based on FexCo1-xSb3. The process is based on precipitation of a precursor material with the desired metal atom composition, which is then exposed to thermochemical processing of calcination followed by reduction. The resultant material thus formed maintains nanostructured particles which are then compacted using Spark Plasma Sintering (SPS) by utilizing previously optimized process parameters. Microstructure, crystallinity, phase composition, thermal stability and temperature dependent transport property evaluation has been performed for compacted NS FexCo1-xSb3. Evaluation results are presented in detail, suggesting the feasibility of devised strategy for bulk quantities of doped TE nanopowder fabrication.
We report on the development and capabilities of two new measurement systems developed at Fraunhofer-IPM. The first measurement system is based on an extension of the Van der Pauw method and is suitable for cube-shaped samples. A mapping of the electrical conductivity tensor of a Skutterudite-SPS samples produced at the Instituto de Microelectrónica de Madrid is presented. The second measurement system is a ZTmeter also developed at the Fraunhofer-IPM. It enables the simultaneous measurement of the electrical conductivity, Seebeck coefficient and thermal conductivity up to 900 K of cubes at least 5x5x5 mm3 in size. The capacity of this measurement system for measuring the anisotropy of the transport properties of a (Bi,Sb)2Te3SPS sample produced by KTH is demonstrated by simply rotating the samples.
Skutterudites are known to be efficient thermoelectric (TE) materials in the temperature range from 600 K to 900 K. Dimensionless figure of merit (ZT) for filled skutterudite TE materials have been reported as ca. 1 at 800 K. Novel nano- engineering approaches and filling of the skutterudites crystal can further improve the transport properties and ultimately the ZT. Although classified among the promising TE materials, research on their large-scale production via bottom up synthetic routes is rather limited. In this work, large quantity of cobalt antimonide (CoSb3) based skutterudites nanopowder (NP) was fabricated through a room temperature co-precipitation precursor method. Dried precipitates were process by thermo-chemical treatment steps including calcination (in air) and reduction (in hydrogen). CoSb3 NPs were then mixed with silver (Ag) nanoparticles at different weight percentages (1%, 5% and 10% by wt) to form nanocomposites. Skutterudite NP was then consolidated by Spark Plasma Sintering (SPS) technique to produce highly dense compacts while maintaining the nanostructure. Temperature dependent TE characteristics of SPS’d CoSb3 and Ag containing nanocomposite samples were evaluated for transport properties, including thermal conductivity, electrical conductivity and Seebeck coefficient over the temperature range of 300 - 900 K. Physicochemical, structural and microstructural evaluation results are presented in detail.
(Bi,Sb)2Te3 + 4 mol%PbTe was quenched in water and on a rotating copper wheel (melt spinning). It was found that PbTe was immiscible in (Bi,Sb)2Te3 when the material is quenched in water and that the thermoelectric figure of merit increases by annealing. Natural nanostructures (nns) were found in melt-spun (Bi,Sb)2Te3, whereas they were hard to detect in (Bi,Sb)2Te3 alloyed with PbTe. There is a correlation between the orientation of the strain field and the nns. Within the grains of melt-spun (Bi,Sb)2Te3 alloyed with PbTe, the chemical composition was homogeneous. An enrichment of Pb was found at the grain boundaries. Quenched (Bi,Sb)2Te3 alloyed with 0.3 wt%PbTe have been spark plasma sintered (SPS). After optimization, the Seebeck coefficients of the melt-spun SPS (MS-SPS) materials were larger than for materials quenched in water and sintered (QW-SPS) materials. In addition, the mobility increases with the carrier concentration in MS-SPS materials, whereas it decreases in QW-SPS materials.
Les traitements de surface, leurs choix et leurs performances souvent rassemblés dans la
terminologie «ingénierie des surfaces» sont un large domaine, primordial pour obtenir les
performances et les propriétés recherchées sur les composants réalisés à partir d’alliages
métalliques. Après avoir rappelé l’importance de la phase de préparation et les différents
mécanismes intervenant lors de la fabrication d’un revêtement ou dépôt ainsi que les
objectifs justifiant l’application de ces derniers, un classement basé sur les
technologies utilisées est proposé en rappelant les principes, les principales
applications et propriétés ainsi que les dernières évolutions de chacun des domaines. En
dernière partie une réflexion sur les évolutions annoncées des traitements de surface est
proposée, elle s’appuie sur les exigences réglementaires et sur les nouvelles technologies
disponibles. En guise de conclusion, la synthèse d’une étude prospective à l’horizon 2015
et 2020 réalisée par le CETIM et la FIM (Centre technique des industries mécaniques;
Fédération des industries mécaniques) est proposée.
With electrostatic probes, the electric field component E∥ along the magnetic field B was comprehensively investigated in a collisionless plasma, the density of which was of the order of 1010 cm-3. The plasma in the experiment has several properties in common with the plasma of the ionosphere/magnetosphere scaled to laboratory dimensions. It is produced by means of electron cyclotron resonance in a microwave cavity located in the magnetic field gradient in one half of a magnetic mirror field. The magnetic field strength is 3600G in the resonance zone and 1800G in the middle of the mirror field. The measurements show that a stationary E∥ exists everywhere in the plasma, where the magnetic field gradient grad11 B in the direction of the field is different from zero. The direction of E‖ is opposite to that of grad‖B. The total potential drop along B between the resonance zone and the midplane of the mirror field is of the order of kilovolts. E‖ accelerates ions along B to energies of the order of kilo electron volts. Experimental parameters of importance for the production of E‖ are the neutral gas pressure p (normally a few times 10− Torr), the microwave power (usually about 2kW), and the mirror ratio γ in the mirror region opposite to the cavity side, γ was normally <2. For γ>2·3, an instability develops and no stationary E‖ remains. As p is increased, E‖ decreases successively. In terms of the mean free path λ, it is found that λ>5−10L is a necessary condition for the existence of E‖. L is twice the distance between the cavity and the midplane of the mirror field. In the experiment, the ion and electron pitch angle distributions are forced to be different; the ion velocity is mainly parallel to B, and the electron velocity essentially perpendicular to JB, and as consequence E‖ is created. In this way an experimental demonstration is presented of the theoretically predicted relation between E‖ and the pitch angle distributions. When imposing sufficiently strong radial electric fields Er (fields perpendicular to B), the distribution of the potential along B is deformed, probably due to changes in the particle distributions caused by E‖. We think that our results strongly support the idea that Et is produced in the magnetosphere, and is at least sometimes an important mechanism for the acceleration and precipitation of auroral particles.
The melt spinning technique (MST) combined with post annealing processes is evaluated for the development of thermoelectric nanocomposites. The evaluated ones are based on two components almost immiscible in solid state but with crystallographic correlation. One is taken from the V-VI-components system and the other one from the IV-VI-components system. This concept was applied to p-(Bi0,2Sb0,8)2Te3 and to p-[(Bi0,2Sb0,8)2Te3]1-xPbTex composites. MST samples of all types were characterised for some structural and thermoelectric properties. All V-VI materials are clearly textured after MST and show no deterioration concerning the thermoelectric properties even after subsequent annealing processes. Structural analysis of p-[(Bi0,2Sb0,8)2Te3]1-xPbTex composites gave significant hints for oriented precipitates of a IV-VI-rich phase incorporated into the V-VI-rich matrix. The thermoelectric figure of merit of the evaluated composites could be enhanced by suitable annealing procedures of both the quenched bulk materials and the melt spin material.
N-type conduction was observed in epitaxial Pb1-xSnxSe and Pb1-xSnxTe thin films grown by MBE with an increasing charge carrier concentration as well as an increasing thermopower value related to an increasing tin content reaching up to 12at%. The lattice thermal conductivity decreases as expected due to alloy scattering but the carrier mobility is almost stable. All these effects increase strongly the thermoelectric properties of Pb1-xSnxSe and Pb1-xSnxTe. The n-type conduction arises from a metal excess in the stoichiometry range. The same type of conduction has also been found in bulk samples. Bulk single crystals of Pb1-xSnxSe and Pb1-xSnxTe are grown by the unseeded vapor growth technique. A rather constant mobility and a decreasing thermal conductivity with increasing tin content are measured in the n-type bulk samples. A figure of merit of ZT=0.9 was measured at 325°C for a Pb0,965Sn0,035Se sample with a carrier concentration of about 9.3E18 cm-3, i.e. already better than known n-type PbTe-based materials for this temperature range.
This paper reports the integration of poled 10μm +/- 1μm P(VDF-TrFe) copolymer thin films with an adapted non-volatile, foundry-compatible CMOS structure (CνMOS) for the potential purposes of in-vivo piezoelectric and pyroelectric sensing. This structure allows for direct, reliable interaction between the sensing transducer and the highly sensitive MOSET gate stack without the need for an external reference electrode or chopper, as other designs may require.
The heavy steel plates (100 - 300 mm) require a good geometric stability during
the manufacturing operations by end users. This stability depends on the residual
stress state inherited from the manufacturing process. This residual stress state is
assessed by an ultrasonic testing method : the acoustical birefringence. The first tests
carried out on representative heavy plates allowed to define the most suitable measurement
configurations and to identify the residual stress states that could generate shape
defects. Then, this method was applied to industrial heavy plates with success.
Lead telluride thin films have been grown on BaF2(111) substrates by pulsed laser deposition from a Nd:YAG laser (λ = 532 nm) at very low temperature (150°C). The chemical composition, the morphology and the crystallographic structure of the layers depend strongly on the deposition conditions. Post-annealing treatments of the films also affect their microstructure. Preliminary electrical properties, conducted in the temperature range of 5 to 350 K, revealed that all the samples were n-type with Hall mobility values greater than 104 cm2/V.s at low temperatures.
The degree of synchrony of light/dark-adapted Chlamydomonas reinhardtii cell-wall-less cells was analysed by flow cytometry. The
cultures exhibited the classical growth curve reported for synchronously dividing cells. However, analysis of the nuclear DNA content
revealed a partial asynchrony of cell division. This allowed us to determine that cell division lasts only 1 h 15 min. The changes in the
distribution of nuclei in G1 and S phases did not exhibit the DNA peaks expected for highly synchronous cells. However, these peaks
were observed for the G2+M nuclei and reflected the number of cell divisions. Modification of culture conditions including temperature,
photoperiod, quantum irradiance and culture density affected the degree of synchrony but did not completely abolish the asynchrony. An
overlap between the divisions of cells dividing one, two or three times could account for the partial asynchrony observed. In fact, it is
possible that cells perform their divisions synchronously but that the timing and/or the duration of the cell divisions is different for the
three kinds of cells. The synchrony seems to be perturbed when the cells move from the G1 to the S phase. The transduction of the
release signal, allowing cells to pass through the restriction point of the G1 phase, might be too slow and insufficiently homogeneous
between the cells to allow perfect synchronization. Finally, if highly synchronized cells are needed to study Chlamydomonas reinhardtii cell
cycle, other synchronization procedures should be considered.
The thioredoxin action upon the 2-oxoacid dehydrogenase
complexes is investigated by using different thioredoxins,
both wild-type and mutated. The attacking cysteine residue
of thioredoxin is established to be essential for the thioredoxin-dependent
activation of the complexes. Mutation of the buried cysteine
residue to serine is not crucial for the activation, but
prevents inhibition of the complexes, exhibited by the
Clamydomonas reinhardtii thioredoxin m
disulfide. Site-directed mutagenesis of D26, W31, F/W12,
and Y/A70 (the Escherichia coli thioredoxin numbering
is employed for all the thioredoxins studied) indicates
that both the active site and remote residues of thioredoxin
are involved in its interplay with the 2-oxoacid dehydrogenase
complexes. Sequences of 11 thioredoxin species tested biochemically
are aligned. The thioredoxin residues at the contact between
the α3/310 and α1 helices, the length
of the α1 helix and the charges in the α2-β3
and β4-β5 linkers are found to correlate with the
protein influence on the 2-oxoacid dehydrogenase complexes
(the secondary structural elements of thioredoxin are defined
according to Eklund H et al., 1991, Proteins 11:13–28).
The distribution of the charges on the surface of the thioredoxin
molecules is analyzed. The analysis reveals the species
specific polarization of the thioredoxin active site surroundings,
which corresponds to the efficiency of the thioredoxin
interplay with the 2-oxoacid dehydrogenase systems. The
most effective mitochondrial thioredoxin is characterized
by the strongest polarization of this area and the highest
value of the electrostatic dipole vector of the molecule.
Not only the magnitude, but also the orientation of the
dipole vector show correlation with the thioredoxin action.
The dipole direction is found to be significantly influenced
by the charges of the residues 13/14, 51, and 83/85, which
distinguish the activating and inhibiting thioredoxin disulfides.
Thioredoxins are ubiquitous small-molecular-weight proteins (typically
100–120 amino-acid residues) containing
an extremely reactive disulphide bridge with a highly conserved sequence
bacteria and animal cells, thioredoxins participate in multiple reactions
which require reduction of disulphide
bonds on selected target proteins/enzymes. There is now ample biochemical
evidence that thioredoxins exert very
specific functions in plants, the best documented being the redox regulation
of chloroplast enzymes. Another area
in which thioredoxins are believed to play a prominent role is in reserve
protein mobilization during the process of
germination. It has been discovered that thioredoxins constitute a large
multigene family in plants with different
subcellular localizations, a unique feature in living cells so far. Evolutionary
studies based on these molecules will
be discussed, as well as the available biochemical and genetic evidence
to their functions in plant cells.
Eukaryotic photosynthetic plant cells are also unique in that they possess
two different reducing systems, one
extrachloroplastic dependent on NADPH as an electron donor, and the other
one chloroplastic, dependent on
photoreduced ferredoxin. This review will examine in detail the latest
in the area of thioredoxin
structural biology in plants, this protein being an excellent model for
purpose. The structural features of the
reducing enzymes ferredoxin thioredoxin reductase and NADPH thioredoxin
reductase will also be described.
The properties of the target enzymes known so far in plants will be detailed
with special emphasis on the structural
features which make them redox regulatory. Based on sequence analysis,
evidence will be presented that redox
regulation of enzymes of the biosynthetic pathways first appeared in
cyanobacteria possibly as a way to cope with
the oxidants produced by oxygenic photosynthesis. It became more elaborate
in the chloroplasts of higher plants
where a co-ordinated functioning of the chloroplastic and extra
chloroplastic metabolisms is required.