Distribution of free amino acids,polyphenols and sugars of Ziziphus jujuba pulps harvested from plants grown in Tunisia

Ziziphus jujuba pulps are very much appreciated by the inhabitants and have been recently exported. This article reports on the chemical composition (amino acids, polyphenols and sugars) of the pulps of four Z. jujuba ecotypes (Choutrana, Mahdia, Mahres and Sfax). The major amino acids identified were proline, aspartic acid and glutamic acid. Among these, proline was the most abundant amino acid (17.4 mol). Considerable differences in total phenolic contents (15.85 mg/L) were found. Predominant phenols identified by using HPLC were rutin (1.09 mg/L) and chlorogenic acid (2.57 mg/100 g). Sugars isolated from Ziziphus pulps were found at a rate of 43.52%. Using HPLC method, three sugars from the pulp extract were identified: glucose, galactose and sucrose. The Mahdia ecotype was the richest in these sugars with 0.45, 136.51 and 113.28 mg/L, respectively.     

Bifurcations in the wake of a thick circular disk

Using DNS, we investigate the dynamics in the wake of a circular disk of aspect ratio χ = d/w = 3 (where d is the diameter and w the thickness) embedded in a uniform flow of magnitude U ₀ perpendicular to its symmetry axis. As the Reynolds number Re = U ₀ d/ν is increased, the flow is shown to experience an original series of bifurcations leading to chaos. The range Re ${\in}$ [150, 218] is analysed in detail. In this range, five different non-axisymmetric regimes are successively encountered, including states similar to those previously identified in the flow past a sphere or an infinitely thin disk, as well as a new regime characterised by the presence of two distinct frequencies. A theoretical model based on the theory of mode interaction with symmetries, previously introduced to explain the bifurcations in the flow past a sphere or an infinitely thin disk (Fabre et al. in Phys Fluids 20:051702, 2008), is shown to explain correctly all these results. Higher values of the Reynolds number, up to 270, are also considered. Results indicate that the flow encounters at least four additional bifurcations before reaching a chaotic state.     

Using GPU parallelization to perform realistic simulations of the LPCTrap experiments

We performed classical molecular dynamics (MD) simulations in order to search the conditions for efficient sympathetic cooling of highly charged ions (HCIs) in a linear Paul trap. Small two-component ion Coulomb crystals consisting of laser-cooled ions and HCIs were characterized by the results of the MD simulations. We found that the spatial distribution is determined by not only the charge-to-mass ratio but also the space charge effect. Moreover, the simulation results suggest that the temperature of HCIs do not necessarily decrease with increasing the number of laser-cooled ions in the cases of linear ion crystals. We also determined the cooling limit of sympathetically cooled ¹⁶⁵Ho¹⁴⁺ ions in small linear ion Coulomb crystals. The present results show that sub-milli-Kelvin temperatures of at least 10 Ho¹⁴⁺ ions will be achieved by sympathetic cooling with a single laser-cooled Be⁺.     

Precision measurements with LPCTrap at GANIL

The experimental achievements and the results obtained so far with the LPCTrap device installed at GANIL are presented. The apparatus is dedicated to the study of the weak interaction at low energy by means of precise measurements of the β ? ν angular correlation parameter in nuclear β decays. So far, the data collected with three isotopes have enabled to determine, for the first time, the charge state distributions of the recoiling ions, induced by shakeoff process. The analysis is presently refined to deduce the correlation parameters, with the potential of improving both the constraint deduced at low energy on exotic tensor currents (⁶He¹⁺) and the precision on the V _{u d} element of the quark-mixing matrix (³⁵Ar¹⁺ and ¹⁹Ne¹⁺) deduced from the mirror transitions dataset.     

Nonreciprocal devices in integrated optics

This article reviews the solutions that have been studied for the implementation of nonreciprocal devices in integrated optics. These components, either isolators or circulators, use the nonreciprocal interaction between light and a magnetic medium. The only two isolators that have been experimented on to date are described in detail with their advantages and drawbacks, and some solutions are proposed to overcome the difficulties encountered.     

A low-cost high-precision measurement method of string motion

The high-precision measurement of a string?s motion requires either the use of an expensive apparatus or the development of a dedicated system. In this paper, a cheaper alternative based on opto-switch sensors combined with a suitable calibration is proposed. A sensitivity model requiring only two straightforward preliminary measurements to determine the parameters is presented. A comparison on a bench test between the opto-switch sensor and a high-speed camera has been performed. Results indicate that the calibrated opto-switch provides more accurate measurements of the string?s motion in quasi-static as well as in dynamic states.     

Electropolymerizable 2,2'-Carboranyldithiophenes. Structure-Property Investigations of the Corresponding Conducting Polymer Films by Electrochemistry, UV-Visible Spectroscopy and Conducting Probe Atomic Force Microscopy

Carborane-functionalized conducting polymer films have been electrogenerated in dichloromethane from the anodic oxidation of ortho- (1), meta- (3) and para-carborane (4) isomers linked to two 2-thienyl units. The corresponding electrochemical response was characterized by a broad reversible redox system corresponding to the p-doping/undoping of the polythiophene backbone, the formal potential of which increased in the order poly(1) < poly(3) < poly(4), from ca. 0.50 to 1.15 V vs Ag/Ag(+) 10(-2) M. From further UV-visible spectroscopy analysis, the optical band gap was estimated at 1.8, 2.0 and 2.2 eV for poly(1), poly(3) and poly(4), respectively. The more conjugated and electroconductive character of poly(1) is ascribed to a more planar conformation of the conjugated backbone resulting from an intramolecular β-β' cyclization reaction in the monomer, consequently yielding a fused conjugated polymer. Molecular modeling calculations using the DFT method support this hypothesis. The surface topography and maps of the conductive domains of the electropolymerized films were evaluated by conducting probe AFM. The three polymers exhibit fairly similar morphological characteristics and a surface roughness of ~2 nm. Current-voltage (I-V) characteristics of conducting AFM tip-carborane polymer-ITO junctions showed that poly(1) had the highest conductivity.     

Novel Nanomaterials Based on Inorganic Molybdenum Octahedral Clusters

In this contribution, we present a review of our recent works about the design of phosphor nanoparticles and materials based on [Mo₆X₁₄]²⁻ cluster units (X = Cl, Br, I) as well as the functionalization of monocrystalline Si(111) surfaces by Mo₆ clusters. Our purpose was to use the specific properties of cluster units found in inorganic solids for the design of new nanomaterials with potential applications in nanotechnologies (e.g. phosphor dyes for bio labelling, light emitting diodes, redox active molecular junctions…) using soft chemistry techniques. Phosphor Cs₂Mo₆X₁₄@SiO₂ nanoparticles emitting in 550–900 nm upon photo-excitation were synthesised using a ‘water in oil’ microemulsion technique. They exhibit a regular shape (~45 nm) and are based on [Mo₆X₁₄]²⁻ cluster units and Cs⁺ counter cations embedded in a silica matrix. ((n–C₄H₉)₄N)₂Mo₆Br₁₄@ZnO colloids and nanopowders are based on the association of ZnO crystalline nano-particles with Mo₆ cluster units adsorbed on their surface. They exhibit a large emission window in the visible region that can be tuned by modulation of the excitation wave length in order to selectively obtain the emission of either clusters units or ZnO nanocrystals or of both entities. Functionalized surfaces were obtained by the attachment of cluster units on a Si(111) surface through pyridine end capped organic chains using a multi-step procedure. Modified surfaces were characterized by X-ray photoemission spectroscopy (XPS), atomic force microscopy (AFM), IR and electrochemical analysis. The surface coverage can be modulated by the controlled introduction of inert organic chains among pyridine end-capped ones before the cluster anchoring step.     

Aspects dynamiques du contact unilatéral entre un fluide et une structure

The unilateral contact between a structure and a fluid is difficult to modelize for several reasons: first of all the wet surface of the structure is an unknown; secondly the coupling with the movements of the structure can be very complex and finally the interaction with the waves (even if the eigenfrequencies of the structure and the one of the fluids are very different) can be at the origin of very stiff solutions. This notes aims at giving a simple mathematical model based on two penalty-integration methods which enables one to reproduce the extreme cases where the energy release rate is 0 or 1. It is proved that this model is well posed and an asymptotic analysis versus the penalty parameter is carried out.