Flexible Thermoelectric Polymer Composites Based on a Carbon Nanotubes Forest

Polymer‐based composites are of high interest in the field of thermoelectric (TE) materials because of their properties: abundance, low thermal conductivity, and nontoxicity. In applications, like TE for wearable energy harvesting, where low operating temperatures are required, polymer composites demonstrate compatible with the targeted specifications. The main challenge is reaching high TE efficiency. Fillers and chemical treatments can be used to enhance TE performance of the polymer matrix. The combined application of vertically aligned carbon nanotubes forest (VA‐CNTF) is demonstrated as fillers and chemical post‐treatment to obtain high‐efficiency TE composites, by dispersing VA‐CNTF into a poly (3,4‐ethylenedioxythiophene) polystyrene sulfonate matrix. The VA‐CNTF keeps the functional properties even in flexible substrates. The morphology, structure, composition, and functional features of the composites are thoroughly investigated. A dramatic increase of power factor is observed at the lowest operating temperature difference ever reported. The highest Seebeck coefficient and electrical conductivity are 58.7 µV K^?1 and 1131 S cm^?1, respectively. The highest power factor after treatment is twice as high in untreated samples. The results demonstrate the potential for the combined application of VA‐CNTF and chemical post‐treatment, in boosting the TE properties of composite polymers toward the development of high efficiency, low‐temperature, flexible TEs.     

Si-As合金平界面凝固过程实验数据的新阐释

建立一个分析模型来描述Si?As合金在测得的界面速率范围内的凝固过程。分析表明：在低界面速率下,凝固发生在初始瞬态。因考虑了在高界面速率下的局部非平衡效应和在低界面速率下的稳态效应,这个模型与实验数据吻合较好。局部非平衡扩散效应缩小了初始瞬态过程,并导致了高界面速率下的无扩散凝固。     

Versatile levitation facility for structural investigations of liquid metals

A versatile levitation facility for structural investigations of liquid metals was developed. It consists of a vacuum-tight process chamber containing a nozzle for aerodynamic levitation and a coil for inductive heating. The chamber is designed for structural investigations by x-ray diffraction and by x-ray absorption. The levitation facility has been used on beamline ID15 at ESRF in Grenoble. High Energy X-Ray diffraction measurements of liquid Al-based alloys using an image plate detector were performed. This paper discusses the experimental set-up for diffraction measurements, and presents first results obtained on liquid Al25at%Ni. The short range order was studied as a function of temperature and composition. Nearest neighbour distances as well as coordination numbers were determined. A pronounced prepeak in the scattering function S(Q) was found.     

Erbium implanted silicon rich oxide thin films suitable for slot waveguides applications

Thin (50 nm) erbium implanted silicon rich oxide films suitable for slot waveguides applications have been produced and studied by means of optical spectroscopy and structural characterisation techniques. Comparison between different deposition techniques in terms of light emitting properties of erbium ions is presented. Special attention is given to the efficiency improvement of the energy transfer from silicon nanoclusters to erbium ions where the type of annealing treatment is proven to be of crucial importance.     

Morphology- and magnetism-controlled electrodeposition of Ni nanostructures on TiO2 nanotubes for hybrid Ni/TiO2 functional applications

We investigate magnetic properties of nickel nanoparticles electrodeposited on TiO₂ nanotubes by different techniques including direct current (DC) and cyclic voltammetry (CV) deposition. TiO₂ nanotubes were fabricated by anodic oxidation from an organic electrolyte under constant voltage on Ti substrates. Using scanning and transmission electron microscopies, we observe that each technique provides different morphologies: DC electrodeposition makes large coalesced Ni nanoparticles mostly accumulated on top surface and mouths of the nanotubes, whereas CV deposition produces a homogenous dispersion of Ni nanoparticles across the nanotubes. The variation of coercivity and saturation magnetization values recorded is consistent with our scenario, though owing to large number of nanoparticles with size and shape varieties. The first order reversal curve (FORC) diagrams help to reveal the magnetic behavior of nanoparticle ensembles in relation to their morphology and crystal structure.     

Silica coating of Fe3O4 magnetic nanoparticles with PMIDA assistance to increase the surface area and enhance peptide immobilization efficiency

The high efficiency of using N-(phosphonomethyl)iminodiacetic acid (PMIDA) as a surfactant for formation of a silica coating on Fe₃O₄ magnetic nanoparticles (MNPs) with a large surface area has been demonstrated. The coating of PMIDA-stabilized MNPs with silica and their further APS-functionalization significantly increased the specific area (up to 203 m² g^?1) and the number of amino groups (up to 1.12 mmol/g) grafted on their surface compared to nanomaterials synthesized without preliminary SiO₂-coating. The comparative study of the peptide modification efficiency, using as an example pH-low insertion peptide (pHLIP), of MNPs coated with 3-aminopropylsilane (APS) or SiO₂/APS was carried out. It has been shown that silica coating of PMIDA-stabilized MNPs leads to a significant increase in the degree of immobilization of the peptide (up to 22 μmol per g of MNPs). Comprehensive characterization of the obtained materials at each stage of the synthesis was carried out using scanning electron microscopy (SEM), energy dispersive X-ray fluorescence spectroscopy (EDX), BET analysis, ATR Fourier transformed infrared spectroscopy (FTIR), termogravimetric analysis (TGA), CHN-elemental analysis, dynamic light scattering (DLS), and vibrating sample magnetometry (VSM). The proposed approach to applying SiO₂-coating of MNPs can be useful for design of new materials for biomedical and chemical purposes.     

Organometallic radical-adducts of fullerenes C60, C70, and single-walled carbon nanotubes derived from (cyclopentadienyl)molybdenumtricarbonyl dimer

Interaction of the metal-centered free radicals [CpMo(CO)3]* generated photochemically from the corresponding dimer [CpMo(CO)3]2 with fullerenes C60, C70, or single-walled carbon nanotubes in toluene results in the radical-adducts investigated by using TGA, ESR, Raman and X-ray Photo-electron spectroscopy. Comparison was made with the chromium analogues previously studied.     

Robust fractional order singular Kalman filter

In this article, the state estimation problem of linear fractional order singular (FOS) systems subject to matrix uncertainties is investigated where a recursive robust algorithm is derived. Considering an uncertain discrete-time linear FOS system with added process and measurement noises, we aim to design a robust Kalman-type state estimation algorithm based on an optimal data fitting approach with a given sequence of observations. As a substitute for the stochastic formulation, this general filter is obtained by minimizing a completely deterministic regularized residual norm in its worst-possible form at each step over admissible uncertainties. Analysis of the algorithm shows that not only does the proposed robust filter cover the traditional robust Kalman filters (KFs), but it also represents an extension of the nominal fractional singular KF (FSKF) when the system is not subject to uncertainties. Furthermore, besides giving a sufficient condition for the existence of the robust filter, we derive conditions for the asymptotic properties of the filter, where we demonstrate that the filter and the Riccati equation are stable and converge when an equivalent system is detectable and stabilizable. A numerical example is included to demonstrate the performance of the introduced filter.