Screening of Wood/Forest and Vine By-Products as Sources of New Drugs for Sustainable Strategies to Control Fusarium graminearum and the Production of Mycotoxins

Fusarium graminearum is a fungal pathogen that can colonize small-grain cereals and maize and secrete type B trichothecene (TCTB) mycotoxins. The development of environmental-friendly strategies guaranteeing the safety of food and feed is a key challenge facing agriculture today. One of these strategies lies on the promising capacity of products issued from natural sources to counteract crop pests. In this work, the in vitro efficiency of sixteen extracts obtained from eight natural sources using subcritical water extraction at two temperatures was assessed against fungal growth and TCTB production by F. graminearum. Maritime pine sawdust extract was shown to be extremely efficient, leading to a significant inhibition of up to 89% of the fungal growth and up to 65% reduction of the mycotoxin production by F. graminearum. Liquid chromatography/mass spectrometry analysis of this active extract revealed the presence of three families of phenolics with a predominance of methylated compounds and suggested that the abundance of methylated structures, and therefore of hydrophobic compounds, could be a primary factor underpinning the activity of the maritime pine sawdust extract. Altogether, our data support that wood/forest by-products could be promising sources of bioactive compounds for controlling F. graminearum and its production of mycotoxins.     

Synthetic Organic Design for Solar Fuel Systems

From the understanding of biological processes and metalloenzymes to the development of inorganic catalysts, electro‐ and photocatalytic systems for fuel generation have evolved considerably during the last decades. Recently, organic and hybrid organic systems have emerged to challenge the classical inorganic structures through their enormous chemical diversity and modularity that led earlier to their success in organic (opto)electronics. This Minireview describes recent advances in the design of synthetic organic architectures and promising strategies toward (solar) fuel synthesis, highlighting progress on materials from organic ligands and chromophores to conjugated polymers and covalent organic frameworks.     

Topological solitons in three-band superconductors with broken time reversal symmetry

We show that three-band superconductors with broken time reversal symmetry allow magnetic flux-carrying stable topological solitons. They can be induced by fluctuations or quenching the system through a phase transition. It can provide an experimental signature of the time reversal symmetry breakdown.     

High-field magnetic phases of a two-leg spin ladder: Cu2(C5H12N2)2Cl4

CHCupCl is a two-leg spin-ladder where the Cu⁺⁺ ions are coupled by superexchange. Its magnetic properties change dramatically as a function of a magnetic field. Below the critical field H_c1, there is a singlet ground state separated from the triplet excited state by an energy gap. Between H_c1 and H_c2, several magnetic phases have been observed. Above 1 K, dynamical studies reveal a disordered quantum critical phase. At lower temperatures, a 3-D ordered phase has been observed in specific heat and NMR studies. New NMR results on the 3D-ordered and quantum critical phases are presented in this short report.     

Observation of a motional Stark effect to determine the second-order Doppler effect

The high resolution two-photon spectroscopy of hydrogen is often limited by the second-order Doppler effect. To determine this effect, we apply a magnetic field perpendicular to the atomic beam. This field induces a quadratic motional Stark shift proportional, as the second-order Doppler effect, to v(2) (v atomic velocity). For some magnetic field, these two effects are opposite and the total shift due to the atomic velocity is reduced. We present the first observation of this effect for the 1S-3S transition in hydrogen.     

From Multifractal Measures to Multifractal Wavelet Series

Given a positive locally finite Borel measure μ on R, a natural way to construct multifractal wavelet series is to set , where . Indeed, under suitable conditions, it is shown that the function F_μ inherits the multifractal properties of μ. The transposition of multifractal properties works with many classes of statistically selfsimilar multifractal measures, enlarging the class of processes which have self-similarity properties and controlled multifractal behaviors. Several perturbations of the wavelet coefficients and their impact on the multifractal nature of F_μ are studied. As an application, multifractal Gaussian processes associated with F_μ are created. We obtain results for the multifractal spectrum of the so-called W-cascades introduced by Arnéodo et al.     

Studies of the local structure in LixNi0.7Co0.3O2 (0.5≤x≤1.0) cathode materials

Among the Li_xNi_1−yCo_yO₂ system, LiNi_0.7Co_0.3O₂ is being considered one of the best cathode materials due to its small volume cell expansion upon charge-discharge cycling. In order to study the modifications of structural and physical properties occurring in the cathode materials during charge, different Li_xNi_0.7Co_0.3O₂ samples (0.5 ≥ x ≥ 1.0) were prepared by electrochemical lithium deintercalation in non-aqueous cells. During the first charge of the Li//Li_xNi_0.7Co_0.3O₂ cell, the structural change in the cathode lattice was followed by both x-ray powder diffraction and FTIR spectroscopy at room temperature. A good correlation is found between XRD data and the local environment of the host lattice. Paper presented at the 5th Euroconference on Solid State Ionics, Benalmádena, Spain, Sept. 13–20, 1998     

Physical properties of LiMn2O4 spinel prepared at moderate temperature

A moderate-temperature method of preparation of the spinel LiMn₂O₄ was developed around 500 °C. Physical features of the products were identified by X-ray photoelectron spectroscopy, X-ray diffractometry, Raman scattering and FTIR spectroscopy. The electronic conductivity of LiMn₂O₄ has been studied as a function of annealing temperature. The product LiMn₂O₄ is identified as a micron-sized powder and analysis of the local environment is in good accordance with the classical structural model of Fd3m space group. LiMn₂O₄ exhibits an electrical conductivity of 1.9×10⁻⁵ S/cm at room temperature with an activation energy of 0.16 eV which corresponds to an electron hopping mechanism between the two charge states of Mn³⁺ and Mn⁴⁺ ions. A first-order phase transition is observed at 292 K.