Properties of a single vortex solution in a rotating Bose Einstein condensate

In this Note, we study the properties of the line energy for a vortex γ in a Bose Einstein condensate rotating at velocity $\text{Ω}$. The global minimizer is either the vortex free solution or U vortices which exist only for $\text{Ω}$ bigger than a critical value. For all values of $\text{Ω}$, we prove the existence of an S type vortex, which is a critical point of the line energy, observed in the experiments. We also prove uniqueness of the minimizer for almost every $\text{Ω}$ and a monotonicity property of the curve γ with respect to $\text{Ω}$. The proofs rely on a related isoperimetric problem. To cite this article: A. Aftalion, R.L. Jerrard, C. R. Acad. Sci. Paris, Ser. I 336 (2003).     

Lowest Landau level approach in superconductivity for the Abrikosov lattice close to $$H_{{c}_{2}}$$

We study the Ginzburg–Landau energy for a superconductor submitted to a magnetic field just below the “second critical field” . When the Ginzburg–Landau parameter ε is small, we show that the mean energy per unit volume can be approximated by a reduced energy on a torus. Moreover, we expand this reduced energy in terms of : when this quantity gets small, the problem amounts to a minimization problem on a finite-dimensional space, equivalent to the “lowest Landau level” in other approaches. The functions in this finite-dimensional space can themselves be expressed via the Jacobi Theta function of a lattice. This connects the Ginzburg–Landau energy to the “Abrikosov problem” of locating vortices optimally on a lattice.      

New acorane sesquiterpenes isolated from the endophytic fungus Colletotrichum gloeosporioides SNB-GSS07

Looking for new anti-glycation compounds, four new acorane sesquiterpenes together with seven known molecules were isolated from Colletrotrichum gloeosporioides, an endophytic fungus of Sabicea cinerea. Their structures were established based on mass spectrometry and NMR, together with circular dichroism for their absolute configurations.     

Photoactive Polyoxometalate/DASA Covalent Hybrids for Photopolymerization in the Visible Range

The synthesis of TBA-DASA-POM-DASA , the first photoactive covalent hybrid polyoxometalate (POM) incorporating a donor–acceptor Stenhouse adduct (DASA) reverse photochrome, is presented. It has been evidenced that in solution the equilibrium between the colorless cyclopentenone and the highly colored triene conformers is strongly dependent not only on the nature of the solvent but also the countercations, allowing to tune its optical properties. This complex has been further associated to photochromic spironaphtoxazine cations, resulting in a material which can be activated by two distinct optical stimuli. Moreover, when combined with N-methyldiethanolamine, TBA-DASA-POM-DASA constitutes a performing photoinitiating system for polyethylene glycol diacrylate polymerization and under visible light irradiation, a promising result in a domain scarcely developed in POM chemistry.     

Novel Synthetic Approach towards Amino-Substituted Polycyclic Aromatic Hydrocarbons through Electrocyclization of Keteniminium Salts

Polycyclic aromatic hydrocarbons (PAHs) are an important family of molecules in science and technology. Amino-substituted PAHs are promising building blocks to create attractive molecules for materials science. However, the synthetic limitations have hampered to produce diverse structures of amino-substituted PAHs. Here we describe a novel efficient synthetic method to access amino-substituted PAHs through the electrocyclization of highly reactive keteniminium species. We demonstrated the synthesis of various amino-substituted PAHs and disclosed some of their photophysical properties. Furthermore, combination with theoretical calculation revealed that the multiple electrocyclization reactions of keteniminium species is a stepwise process and the fusion of additional aromatic ring to the substrate accelerates the electrocyclization.     

Endogenous Synthesis of Tetrahydroisoquinoline Derivatives from Dietary Factors: Neurotoxicity Assessment on a 3D Neurosphere Culture

Tetrahydroisoquinoline (THIQ) alkaloids and their derivatives have a structural similarity to 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), a well-known neurotoxin. THIQs seem to present a broad range of actions in the brain, critically dependent on their catechol moieties and metabolism. These properties make it reasonable to assume that an acute or chronic exposure to some THIQs might lead to neurodegenerative diseases including essential tremor (ET). We developed a method to search for precursor carbonyl compounds produced during the Maillard reaction in overcooked meats to study their reactivity with endogenous amines and identify the reaction products. Then, we predicted in silico their pharmacokinetic and toxicological properties toward the central nervous system. Finally, their possible neurological effects on a novel in vitro 3D neurosphere model were assessed. The obtained data indicate that meat is an alkaloid precursor, and we identified the alkaloid 1-benzyl-1,2,3,4-tetrahydroisoquinoline-6,7-diol (1-benz-6,7-diol THIQ) as the condensation product of phenylacetaldehyde with dopamine; in silico study of 1-benz-6,7-diol-THIQ reveals modulation of dopamine receptor D1 and D2; and in vitro study of 1-benz-6,7-diol-THIQ for cytotoxicity and oxidative stress induction does not show any difference after 24 h contact for all tested concentrations. To conclude, our in vitro data do not support an eventual neurotoxic effect for 1-benz-6,7-diol-THIQ.     

Synthesis of Highly Substituted Cyclobutanones by a One-Pot Keteniminium-Enamine Process

Herein, we describe an effective one-pot sequence for the regio- and stereoselective synthesis of highly substituted cyclobutanones. This process relies on first a [2+2] cycloaddition involving a keteniminium salt intermediate with an alkene followed by isomerization of the resulting cyclobutaniminium salt into its cyclic enamine form and then reaction of the latter with an electrophile. The adduct can be either hydrolyzed or reduced to give the corresponding cyclobutanone or cyclobutanamine, respectively, with excellent diastereocontrol. A variety of electrophiles was tolerated allowing the incorporation of diverse substituents and functionalities onto the cyclobutyl ring. Additionally, the coplanarity of diverse cyclic enamines was investigated through a DFT study.     

Selective Extraction of Sinapic Acid Derivatives from Mustard Seed Meal by Acting on pH: Toward a High Antioxidant Activity Rich Extract

The aim of this paper is to study the effect of the pH on the extraction of sinapic acid and its derivatives from mustard seed meal. Solutions of acidic pH (pH 2), basic pH (pH 12) and distilled water (uncontrolled pH ~ 4.5) were tested at different percentages of ethanol. The maximum extraction yield for sinapic acid (13.22 µmol/g of dry matter (DM)) was obtained with a buffered aqueous solution at pH 12. For ethyl sinapate, the maximum extraction yield reached 9.81 µmol/g _DM with 70% ethanol/buffered aqueous solution at pH 12. The maximum extraction yield of sinapine (15.73 µmol/g _DM) was achieved with 70% ethanol/buffered aqueous solution at pH 2. The antioxidant activity of each extract was assessed by DPPH assay; the results indicated that the extracts obtained at pH 12 and at low ethanol percentages (<50%) exhibit a higher antioxidant activity than extracts obtained at acidic conditions. Maximum antioxidant activity was reached at pH 12 with buffer solution (11.37 mg of Trolox Equivalent/g _DM), which confirms that sinapic acid-rich fractions exhibit a higher antioxidant activity. Thus, to obtain rich antioxidant extracts, it is suggested to promote the presence of sinapic acid in the extracts.