Gauge Gravitational Field in a Fractal Space-Time

Considering the fractal structure of space-time, the scale relativity theory in the topological dimension DT = 2 is built. In such a conjecture, the geodesics of this space-time imply the hydrodynamic model of the quantum mechanics. Subsequently, the gauge gravitational field on a fractal space-time is given. Then, the gauge group, the gauge-covariant derivative, the strength tensor of the gauge field, the gauge-invariant Lagrangean, the field equations of the gauge potentials and the gauge energy-momentum tensor are determined. Finally, using this model, a Reissner- Nordstrom type metric is obtained.     

Computing Topological Entropy in a Space of Quartic Polynomials

This paper adds a computational approach to a previous theoretical result illustrating how the complexity of a simple dynamical system evolves under deformations. The algorithm targets topological entropy in the 2-dimensional family P ^Q of compositions of two logistic maps. Estimation of the topological entropy is made possible by the correspondence between P ^Q and a subfamily of sawtooth maps P ^T , and is based on the well-known fact that the kneading-data of a map determines its entropy. A complex search for kneading-data in P ^T turns out to be computationally fast and reliable, delivering good entropy estimates. Finally, the algorithm is used to produce a picture of the entropy level-sets in P ^Q , as illustration to theoretical results such as Hu (Ph.D. thesis, CUNY, 1995) and Radulescu (Discrete Cont. Dyn. Syst. 19(1):139–175, 2007).     

High-Resolution Tandem Mass Spectrometry Identifies a Particular Ganglioside Pattern in Early Diabetic Kidney Disease of Type 2 Diabetes Mellitus Patients

Considering the valuable information provided by glycosphingolipids as molecular markers and the limited data available for their detection and characterization in patients suffering from Type 2 diabetic kidney disease (DKD), we developed and implemented a superior method based on high-resolution (HR) mass spectrometry (MS) and tandem MS (MS/MS) for the determination of gangliosides in the urine of DKD patients. This study was focused on: (i) testing of the HR MS and MS/MS feasibility and performances in mapping and sequencing of renal gangliosides in Type 2 DM patients; (ii) determination of the changes in the urine gangliosidome of DKD patients in different stages of the disease—normo-, micro-, and macroalbuminuria—in a comparative assay with healthy controls. Due to the high resolution and mass accuracy, the comparative MS screening revealed that the sialylation status of the ganglioside components; their modification by O-acetyl, CH₃COO⁻, O-fucosyl, and O-GalNAc; as well as the composition of the ceramide represent possible markers for early DKD detection, the assessment of disease progression, and follow-up treatment. Moreover, structural investigation by MS/MS demonstrated that GQ1d(d18:1/18:0), GT1α(d18:1/18:0) and GT1b(d18:1/18:0) isomers are associated with macroalbuminuria, meriting further investigation in relation to their role in DKD.     

Development of a routine analysis of 4-mercapto-4-methylpentan-2-one in wine by stable isotope dilution assay and mass tandem spectrometry

The 4-mercapto-4-methylpentan-2-one (4MMP) is a key aroma compound in wines, especially in Sauvignon Blanc ones. Its accurate quantification is quite difficult due to its traces levels and its reactivity in wine conferred by the thiol function. In this paper, we proposed a new method for its quantification in wine without any sample preparation, based on automated derivatization procedure by methoximation and SIDA–SPME–GC–MS/MS analysis. The derivatization procedure was adapted from a previously published method in order to decrease the amount of reagents and the volume of wine (only 3 mL are required). The use of SPME and the detection conditions have also been optimized to reach the best sensitivity as possible. The method was then validated according to the International Organization of Vine and Wine recommendations and exhibited excellent performances. Indeed, this method allowed us to quantify the 4MMP in wine at traces levels (LOD = 0.19 ng L⁻¹) with reproducible results (RSD < 15%) and a very good accuracy (recovery = 102%).     

Three soliton contribution to the specific heat in sine-Gordon systems

The three soliton contribution to the specific heat of a classical easy-plane ferromagnet chain is calculated using asymptotic methods from the theory of differential equations depending on a large parameter.     

Transformation of 5-hydroxymethylene-5H-6,7-dihydrodibenzo[a,c]cyclohepten-6-one over Ru-containing BEA zeolites

Ru–BEA catalysts with 1.0–2.5 wt.% Ru were prepared by ion exchange. The acidic properties of these catalysts were investigated using deuterated acetonitrile, pyridine, and 2,6-di-tert-butyl-pyridine. The deposited Ru was studied by CO-FTIR spectroscopy. The materials were tested as catalysts in the hydrogenation of a conjugated cyclic keto–enol, namely, 5-hydroxymethylene-5H-6,7-dihydrodibenzo[a,c]cyclohepten-6-one. Beside hydrogenation, hydrogenolysis products were identified by GC–MS and ¹H NMR techniques. Relations were sought between the selectivity and some physicochemical properties of the catalyst.     

Chemogenetic protein engineering: an efficient tool for the optimization of artificial metalloenzymes

Artificial metalloenzymes, based on the incorporation of a catalytically active organometallic moiety within a host protein, lie at the interface between organometallic and enzymatic catalysis. In terms of activity, reaction repertoire, substrate range and operating conditions, they take advantage of the versatility of the organometallic chemistry. In contrast, the enantioselectivity is determined by the biomolecular scaffold, which provides a well defined second coordination sphere to the organometallic moiety, reminiscent of enzymes. The attractive feature of such systems is their optimization potential, which combines chemical and genetic methods (i.e. chemogenetic) to screen diversity space. This feature article describes the implementation of such an optimization protocol for artificial transfer hydrogenases, for which we have the most detailed understanding.     

Magnetic beads-based immunoassay as a sensitive alternative for atrazine analysis

A new immunoassay strategy for sensitive atrazine determination based on magnetic beads is reported. The immuno-method is a competitive solid-phase immunoassay where the anti-atrazine antibody is immobilized on the magnetic beads surface and fixed at the reaction cell bottom using a simple magnet, which generates a magnetic field. Analyte and HRP (horseradish peroxidase) tracer compete for active sites of antibody. After the immunointeractions antibody-analyte and antibody-tracer, atrazine quantification from the sample is performed by injection of the chemiluminescence substrate (luminol, hydrogen peroxide and p-iodophenol). Different antibodies (polyIgG anti-atrazine Ab I and affinity purified polyIgG anti-atrazine AbI) were tested in this configuration. Also, optimum concentration of antibody-covered magnetic beads was set up (8 mg/l Ab II). Finally, the performance of magnetic beads-based immunoassay for atrazine determination was evaluated demonstrating that the magnetic beads-based immunoassay is one of the most sensitive method for atrazine determination (LoD = 3 pg/l, IC₅₀ = 37 pg/l, DR = 10-1000 pg/l).     

Identification of S-methylmethionine in Petit Manseng grapes as dimethyl sulphide precursor in wine

A procedure for the extraction of free amino acids was applied to isolate S-methylmethionine (SMM) from late harvest Petit Manseng grapes. Grapes were destemmed and crushed, and the obtained clarified must was percolated through cation-exchange resins (Dowex 50 WX4-100). The retained compounds were eluted with ammonia solution and the extract was finally concentrated. Taking into account the potential DMS (PDMS using heat-alkaline treatment assay) of the initial grape juice used (51.5 nmol mL⁻¹) and the concentration factor of the extract (17.9-fold), the PDMS of the final extract (678 nmol mL⁻¹) gave an overall recovery of 73.5% for juice SMM. This compound was identified and quantified (484.5 nmol mL⁻¹ relatively to [²H₃]-SMM used as internal standard) by its selective detection in this extract without derivatization by MALDI-TOF-MS using instrumentation and procedures previously reported to analyze SMM in complex natural extracts. SMM and 22 other amino acids in the initial must and in the final SMM extract were also determined using a Biochrom 30 amino acid analyser with post-column ninhydrin derivatization. SMM peak identification and quantification (401.2 nmol mL⁻¹ relatively to norleucine used as internal standard) were carried out by comparison with commercial SMM.