Nested Cantor sets

We give sufficient conditions for two Cantor sets of the line to be nested for a positive set of translation parameters. This problem occurs in diophantine approximations. It also occurs as a toy model of the parameter selection for non-uniformly hyperbolic attractors of the plane. For natural Cantors sets, we show that this condition is optimal.     

Assessment of pharmacokinetic interaction between piracetam and l‐carnitine in healthy subjects

A rapid, sensitive and specific method for quantifying piracetam in human plasma using Piracetam d‐8 as the internal standard (IS) is described. The analyte and the IS were extracted from plasma by one‐step precipitation of protein using an acetonitrile (100%). The extracts were analyzed by high‐performance liquid chromatography coupled with electrospray tandem mass spectrometry (HPLC‐MS/MS). The method had a chromatographic run time of 3.8 min and a linear calibration curve over the range 0.5–50 µg/mL (r > 0.99). This LC‐MS‐MS procedure was used to assess the bioavailability of two piracetam formulations: piracetam + l‐carnitine (Piracar®; 270/330 mg tablet) and piracetam (Nootropil®; 800 mg tablet) in healthy volunteers of both sexes. The geometric means with corresponding 90% confidence interval (CI) for test/reference percentage ratios were 88.49% (90% CI = 81.19 – 96.46) for peak concentration/dose and 102.55% (90% CI = 100.62 – 104.51) for AUC_inf/dose. The limit of quantitation of 0.5 µg/mL is well suited for pharmacokinetic studies in healthy volunteers. It was concluded that piracetam (Piracar®; 270/330 mg tablet) has a bioavailability equivalent to the piracetam (Nootropil®; 800 mg tablet) formulation with regard to both the rate and the extent of absorption. Copyright © 2015 John Wiley & Sons, Ltd.     

Separation of isomeric disaccharides by traveling wave ion mobility mass spectrometry using CO2 as drift gas

The use of CO₂ as a massive and polarizable drift gas is shown to greatly improve peak‐to‐peak resolution (R_p‐p), as compared with N₂, for the separation of disaccharides in a Synapt G2 traveling wave ion mobility cell. Near or baseline R_p‐p was achieved for three pairs of sodiated molecules of disaccharide isomers, that is, cellobiose and sucrose (R_p‐p = 0.76), maltose and sucrose (R_p‐p = 1.04), and maltose and lactose (R_p‐p = 0.74). Ion mobility mass spectrometry using CO₂ as the drift gas offers therefore an attractive alternative for fast and efficient separation of isomeric disaccharides. Copyright © 2012 John Wiley & Sons, Ltd.     

XANES speciation of mercury in three mining districts – Almadén,Asturias (Spain), Idria (Slovenia)

The mobility, bioavailability and toxicity of mercury in the environment strongly depend on the chemical species in which it is present in soil, sediments, water or air. In mining districts, differences in mobility and bioavailability of mercury mainly arise from the different type of mineralization and ore processing. In this work, synchrotron‐based X‐ray absorption near‐edge spectroscopy (XANES) has been taken advantage of to study the speciation of mercury in geological samples from three of the largest European mercury mining districts: Almadén (Spain), Idria (Slovenia) and Asturias (Spain). XANES has been complemented with a single extraction protocol for the determination of Hg mobility. Ore, calcines, dump material, soil, sediment and suspended particles from the three sites have been considered in the study. In the three sites, rather insoluble sulfide compounds (cinnabar and metacinnabar) were found to predominate. Minor amounts of more soluble mercury compounds (chlorides and sulfates) were also identified in some samples. Single extraction procedures have put forward a strong dependence of the mobility with the concentration of chlorides and sulfates. Differences in efficiency of roasting furnaces from the three sites have been found.     

Amine containing cationic methacrylate copolymers as efficient gene delivery vehicles to retinal epithelial cells

Non‐viral gene delivery vectors have emerged as potential alternatives in the field of gene therapy by replacing the biological viral vectors. DNA–cationic polymer complexes are one of the most promising systems to target many inborn or acquired diseases without the utilization of conventional drugs. Despite the excellent binding efficiency of cationic polymers, the gene transfection seems limited to date. In this work, a series of ammonium‐based block‐copolymers with different alkyl side chains (ethyl, butyl, and hexyl) and functionality (alcohol, amine, and alkyl) have been prepared to evaluate their capacity to deliver genetic material. First, different ionic liquid monomers with different pendent functional groups were prepared and characterized. Then, polyplexes elaborated with different polymers at several polymer DNA ratios (w/w) were characterized in terms of size, zeta potential, and DNA binding, release, and protection capacity. Finally, the transfection efficiency and cell viability was evaluated in ARPE19 cells. We found that only the systems containing the amine pendent group were able to transfect ARPE19 cell and, that this amine containing polymer was less cytotoxic even at high polymer/DNA ratios (30:1). In conclusion, our studies suggested that the proper selection of the pendent group substantially impacts overall transfection efficiency of cationic polymers. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 280–287     

Thermal, rheological, and structural behaviors of natural and modified cassava starch granules, with sodium hypochlorite solutions

The use of chemically modified starches is widely accepted in various industries, with several applications. In this research, natural cassava starch granules were treated with standard sodium hypochlorite solution at 0.8, 2.0, and 5.0 g Cl/100 g starch. The native and modified starch samples were investigated by means of the following techniques: simultaneous thermogravimetry–differential thermal analysis, which allowed us to verify the thermal decomposition associated with endothermic or exothermic phenomena; and differential scanning calorimetry that was used to determine gelatinization enthalpy as well as the rapid viscoamylographic analysis that provided the pasting temperature and viscosity. By means of non-contact-atomic force microscopy method and X-ray powder patterns diffractometry, it was possible to observe the surface morphology, topography of starch granules, and alterations in the granules’ crystallinity.     

Non-phospholipid liposomes with high sterol content display a very limited permeability

We demonstrate that it is possible to form non-phospholipid fluid bilayers in aqueous milieu with a mixture of palmitic acid (PA),cholesterol (Chol),and cholesterol sulfate (Schol) in a molar proportion of 30/28/42.These self-assemblies are shown to be bilayers in the liquid ordered phase.They are stable between pH 5 and 9.Over this pH range,the protonation/deprotonation of PA carboxylic group is observed but this change does not appear to alter the stability of these bilayers,a behavior contrasting with that observed for binary mixtures of PA/Chol,and PA/Schol.The multilamellar dispersions formed spontaneously from the PA/Chol/Schol mixture could be successfully extruded to form Large Unilamellar Vesicles (LUVs).These LUVs show interesting permeability properties,linked with their high sterol content.These non-phospholipid liposomes can sustain a pH gradient (pH internal 8/pH external 6) 100 times longer than LUVs made of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) and cholesterol,with a molar ratio of 60/40.Moreover,the non-phospholipid LUVs are shown to protect ascorbic acid from an oxidizing environment (1 mM iron(III)).Once entrapped in liposomes,ascorbic acid displays a degradation rate similar to that obtained in the absence of iron(III).These results show the possibility to form novel nanocontainers from a mixture of a monoalkylated amphiphile and sterols,with a good pH stability and showing interesting permeability properties.     

The zwitterionic structure of 2‐hydroxy‐4‐[(2‐hydroxybenzylidene)amino]benzoic acid

The title compound, C₁₄H₁₁NO₄, exists in the solid phase in the zwitterionic form, 2‐{[(4‐carboxy‐3‐hydroxyphenyl)iminiumyl]methyl}phenolate, with the H atom from the phenol group on the 2‐hydroxybenzylidene ring transferred to the imine N atom, resulting in a strong intramolecular N—H...O hydrogen bond between the iminium H atom and the phenolate O atom, forming a six‐membered hydrogen‐bonded ring. In addition, there is an intramolecular O—H...O hydrogen bond between the carboxylic acid group and the adjacent hydroxy group of the other ring, and an intermolecular C—H...O contact involving the phenol group and the C—H group adjacent to the imine bond, connecting the molecules into a two‐dimensional network in the (10) plane. π–π stacking interactions result in a three‐dimensional network. This study is important because it provides crystallographic evidence, supported by IR data, for the iminium zwitterionic form of Schiff bases.<!?tpb=12pt>     

A mixed chloride/trifluoromethanesulfonate ligand species in a ruthenium(II) complex

The compound [2‐(aminomethyl)pyridine‐κ²N,N′][chlorido/trifluoromethanesulfonato(0.91/0.09)][(10,11‐η)‐5H‐dibenzo[a,d]cyclohepten‐5‐amine‐κN](triphenylphosphane‐κP)ruthenium(II) trifluoromethanesulfonate dichloromethane 0.91‐solvate, [Ru(CF₃SO₃)_0.09Cl_0.91(C₆H₈N₂)(C₁₅H₁₃N)(C₁₈H₁₅P)]CF₃SO₃·0.91CH₂Cl₂, belongs to a series of Ru^II complexes that had been tested for transfer hydrogenation, hydrogenation of polar bonds and catalytic transfer hydrogenation. The crystal structure determination of this complex revealed disorder in the form of two different anionic ligands sharing the same coordination site, which other spectroscopic methods failed to characterize. The reduced catalytic activity of the title compound was not fully understood until the crystallographic data provided evidence for the mixed ligand species. The crystal structure clearly shows that the majority of the synthesized material has a chloride ligand present. Only a small portion of the material is the expected complex [Ru^II(OTf)(ampy)(η²‐tropNH₂)(PPh₃)]OTf, where OTf is triflate or trifluoromethanesulfonate, ampy is 2‐(aminomethyl)pyridine and tropNH₂ is 5H‐dibenzo[a,d]cyclohepten‐5‐amine.