Designing nanoparticles during the drawing step

International audienceNanoparticles in the core of optical fibres are widely studied due to the opportunity they give to tailor spectroscopic properties. Such fibres are usually obtained by drawing at high temperature a preform containing nanoparticles. This study focuses on the effect of the fibre drawing on nanoparticles. We fabricated an MCVD optical preform by doping the porous layer with nanoparticles. The optical fibre was studied by a FIB/SEM tomography.Figure 1 is the volume reconstruction of the core of the optical fibre. The yellow phase represents nanoparticles inside the core of the optical fibre. This reconstruction shows evidences of break-up, elongation and coalescence of particles. These features will be discussed according to phenomena well known from the rheology of emulsions and polymers. It comes from a competition between viscous stresses of the flow and surface tension.Observation of these size-controlling phenomena occuring during fibre drawing offer new perspectives to tailor the size of nanoparticles and are therefore of great interest for light scattering issues

Credibility and adjustment: gold standards versus currency boards

It is often maintained that currency boards (CBs) and gold standards (GSs) are alike in that they are stringent monetary rules, the two basic features of which are high credibility of monetary authorities and the existence of automatic adjustment (non discretionary) mechanism. This article includes a comparative analysis of these two types of regimes both from the perspective of the sources and mechanisms of generating confidence and credibility, and the elements of operation of the automatic adjustment mechanism. Confidence under the GS is endogenously driven, whereas it is exogenously determined under the CB. CB is a much more asymmetric regime than GS (the adjustment is much to the detriment of peripheral countries) although asymmetry is a typical feature of any monetary regime. The lack of credibility is typical for peripheral countries and cannot be overcome completely even by “hard” monetary regimes.http://deepblue.lib.umich.edu/bitstream/2027.42/40078/3/wp692.pd

Structural Characterization of Magnetic Nano-particles Suspensions, Using Magnetic Measurements

P curves, Magnetic fluids, Ferrofluids, Nanostructural characterization, Magnetic powders, Hysteresis curve, Magnetic nanocomposite materialsThe paper describes some characteristics of the “P” curves for structural characterization of magnetic nano-particles suspensions (complex fluids, complex powders, complex composite materials, or living biological materials having magnetic properties). In the case of these materials, the magnetic properties are conferred to various carrier liquids by artificially integrating in their structure ferromagnetic particles of different sizes. The magnetic properties are usually shown by the hysteresis curve. The structure can be seen on (electronic) micrography. The P curves offer another possibility to determine the structure of the magnetic component of a complex fluid by numerical analysis of the magnetization curve experimentally obtained. The paper presents a detailed approach of the P curves and some limitations in their use

Pharmacological analysis of transmission activation of two aphid-vectored plant viruses, turnip mosaic virus and cauliflower mosaic virus

Turnip mosaic virus (TuMV, family Potyviridae) and cauliflower mosaic virus (CaMV, family Caulimoviridae) are transmitted by aphid vectors. They are the only viruses shown so far to undergo transmission activation (TA) immediately preceding plant-to-plant propagation. TA is a recently described phenomenon where viruses respond to the presence of vectors on the host by rapidly and transiently forming transmissible complexes that are efficiently acquired and transmitted. Very little is known about the mechanisms of TA and on whether such mechanisms are alike or distinct in different viral species. We use here a pharmacological approach to initiate the comparison of TA of TuMV and CaMV. Our results show that both viruses rely on calcium signaling and reactive oxygen species (ROS) for TA. However, whereas application of the thiol-reactive compound N-ethylmaleimide (NEM) inhibited, as previously shown, TuMV transmission it did not alter CaMV transmission. On the other hand, sodium azide, which boosts CaMV transmission, strongly inhibited TuMV transmission. Finally, wounding stress inhibited CaMV transmission and increased TuMV transmission. Taken together, the results suggest that transmission activation of TuMV and CaMV depends on initial calcium and ROS signaling that are generated during the plant's immediate responses to aphid manifestation. Interestingly, downstream events in TA of each virus appear to diverge, as shown by the differential effects of NEM, azide and wounding on TuMV and CaMV transmission, suggesting that these two viruses have evolved analogous TA mechanisms

Revealing hidden species diversity in closely related species using nuclear SNPs, SSRs and DNA sequences - a case study in the tree genus Milicia

Background: Species delimitation in closely related plant taxa can be challenging because (i) reproductive barriers are not always congruent with morphological differentiation, (ii) use of plastid sequences might lead to misinterpretation, (iii) rare species might not be sampled. We revisited molecular-based species delimitation in the African genus Milicia, currently divided into M. regia (West Africa) and M. excelsa (from West to East Africa). We used 435 samples collected in West, Central and East Africa. We genotyped SNP and SSR loci to identify genetic clusters, and sequenced two plastid regions (psbA-trnH, trnC-ycf6) and a nuclear gene (At103) to confirm species’ divergence and compare species delimitation methods. We also examined whether ecological niche differentiation was congruent with sampled genetic structure. Results: West African M. regia, West African and East African M. excelsa samples constituted three well distinct genetic clusters according to SNPs and SSRs. In Central Africa, two genetic clusters were consistently inferred by both types of markers, while a few scattered samples, sympatric with the preceding clusters but exhibiting leaf traits of M. regia, were grouped with the West African M. regia cluster based on SNPs or formed a distinct cluster based on SSRs. SSR results were confirmed by sequence data from the nuclear region At103 which revealed three distinct ‘Fields For Recombination’ corresponding to (i) West African M. regia, (ii) Central African samples with leaf traits of M. regia, and (iii) all M. excelsa samples. None of the plastid sequences provide indication of distinct clades of the three species-like units. Niche modelling techniques yielded a significant correlation between niche overlap and genetic distance. Conclusions: Our genetic data suggest that three species of Milicia could be recognized. It is surprising that the occurrence of two species in Central Africa was not reported for this well-known timber tree. Globally, our work highlights the importance of collecting samples in a systematic way and the need for combining different nuclear markers when dealing with species complexes. Recognizing cryptic species is particularly crucial for economically exploited species because some hidden taxa might actually be endangered as they are merged with more abundant species

Introduction to special section: Balancing, restoration, and palinspastic reconstruction

Methods to quantify deformation and reverse the process of strain as a mode to illustrate geologic evolution through time have been previously used for a number of decades. Early efforts on the quantification of bed reconstruction were completed either by manually weighing the sections on delicate balances and obtaining the average height and thickness of strata to be reconstructed by applying a scale factor (Chamberlin, 1910), or by hand-drafting sections with conserved bed length between the folded and faulted sedimentary layers, mainly in a 2D cross section (Bally et al., 1966; Dahlstrom, 1969) or map framework (Dennison and Woodward, 1963). Cross-section techniques initially applied to contractional thrust and fold belts and have proven useful in other structural settings, such as extensional and inverted domains. Development of 3D techniques enabled the analysis of strike-slip and salt tectonics where out-of-plane changes of rock volume could be addressed. Through the years, the widespread application of these techniques to predict fault and horizon geometry at depth has generated newer approaches and more sophisticated algorithms, and it has also demonstrated the potential of structural modeling techniques (e.g., construction of balanced sections, palinspastic reconstruction, kinematic and geomechanical restoration, and forward modeling) in reducing the risk and uncertainty associated with the interpretation of geophysical/geological dat

Improved survival prediction and comparison of prognostic models for patients with hepatocellular carcinoma treated with sorafenib

Background: The ‘Prediction Of Survival in Advanced Sorafenib-treated HCC’ (PROSASH) model addressed the heterogeneous survival of patients with hepatocellular carcinoma (HCC) treated with sorafenib in clinical trials but requires validation in daily clinical practice. This study aimed to validate, compare and optimize this model for survival prediction. Methods: Patients treated with sorafenib for HCC at five tertiary European centres were retrospectively staged according to the PROSASH model. In addition, the optimized PROSASH-II model was developed using the data of four centres (training set) and tested in an independent dataset. These models for overall survival (OS) were then compared with existing prognostic models. Results: The PROSASH model was validated in 445 patients, showing clear differences between the four risk groups (OS 16.9-4.6 months). A total of 920 patients (n = 615 in training set, n = 305 in validation set) were available to develop PROSASH-II. This optimized model incorporated fewer and less subjective parameters: the serum albumin, bilirubin and alpha-foetoprotein, and macrovascul

Fabrication and characterization of micro-inductors deposited on magnetic thin and thick layers

This paper presents two fabrication techniques of spiral integrated inductors based on magnetic materials. For the first one, the magnetic core is a thin film deposited by RF magnetron sputtering, for the second technique the magnetic core is a thick layer of YIG obtained by micromachining. The addition of the magnetic material is expected to improve the performances of the integrated structure with electromagnetic shield. Low and high frequency equipment are used to characterize the manufactured components. A good correlation is obtained between the results by simulation and measurements for the two manufacturing techniques. These results show that the inductance increases when the thickness of the magnetic layer increases, we can double the inductance value for a thickness sufficiently high