Antibiotic protected silver nanoparticles for microbicidal cotton

Surface coating of metal nanoparticles is one of the major aspects to be optimized in the design of antimicrobial nanoparticles. The novelty of this work is that antimicrobial derivatives have been used as stabilizers to protect silver nanoparticles (Ag NPs). Microbicidal activity studies of fabricated cotton textiles coated with these Ag@Antibio were performed. Protective ligand layers of Ag NPs resulted to be a deterministic factor in their antimicrobial activity. The best bactericidal activity was obtained for Fabric TAM (coated with Ag NPs with triarylmethane derivates in surface, Ag@TAMSH), with a bacterial decrease of 3 log units for the S. aureus strain. Intrinsic antibiotic activity and partial positive charge of the TAMSH probably enhanced their antimicrobial effects. Fabric Eu (coated with Ag NPs with eugenol derivates in surface, Ag@EugenolSH) and Fabric FQPEG (coated with Ag NPs embedded in PEG-fluoroquinolone derivatives in surface, Ag@FQPEG) displayed antibacterial activity for both Staphylococcus aureus and Pseudomonas aeruginosa strains. These coated antimicrobial cotton fabrics can be applied in different medical textiles.     

Markov shifts and topological entropy of families of homoclinic tangles

The existence of a homoclinic orbit in dynamical systems implies chaotic behaviour with positive entropy. In this work, we determine explicitly the Markov shifts associated to certain Smale horseshoe homoclinic orbits which allow us to compute a lower bound for the topological entropy that such a system can have. It is done associating a heteroclinic orbit which belongs to the same isotopy class and then determining the Markov partition of the dynamical core of an end periodic mapping.     

Assessing the antioxidative properties and chemical composition of Linaria vulgaris infusion

The ability of Linaria vulgaris (Scrophulariaceae) infusion to act as a scavenger of 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical, reactive oxygen species (superoxide radical, hydroxyl radical, hypochlorous acid (HOCl)) and nitric oxide was investigated. The obtained data indicate that the infusion has a good scavenging activity against superoxide radical and is a very potent nitric oxide and DPPH scavenger. In hydroxyl radical assay a pro-oxidant capacity was noticed, especially for concentrations higher than 31.25 microg mL(-1). No effect was found against HOCl. A phytochemical study of this extract was also performed. The HPLC/UV analysis allowed the identification and quantification of eight organic acids (oxalic, aconitic, citric, ketoglutaric, ascorbic, malic, shikimic and fumaric acids). The phenolic composition of the lyophilised infusion was also determined by HPLC/DAD and four compounds were quantified, but, despite its high content, only linarin was managed to be identified.     

Dynamic Kinetic Resolution of 2-(Quinolin-8-yl)Benzaldehydes: Atroposelective Iridium-Catalyzed Transfer Hydrogenative Allylation

An atroposelective Ir-catalyzed dynamic kinetic resolution (DKR) of 2-(quinolin-8-yl)benzaldehydes/1-naphthaldehydes by transfer hydrogenative coupling of allyl acetate is disclosed. The allylation reaction takes place with simultaneous installation of central and axial chirality, reaching high diastereoselectivities and excellent enantiomeric excesses when ortho-cyclometalated iridium-DM-BINAP is used as the catalyst. The racemization of the substrates occurs through a designed transient Lewis acid-base interaction between the quinoline nitrogen atom and the aldehyde carbonyl group.     

Analysis of molecular hydrogen formation on low-temperature surfaces in temperature programmed desorption experiments

The study of the formation of molecular hydrogen on low-temperature surfaces is of interest both because it enables the exploration of elementary steps in the heterogeneous catalysis of a simple molecule and because of its applications in astrochemistry. Here, we report results of experiments of molecular hydrogen formation on amorphous silicate surfaces using temperature-programmed desorption (TPD). In these experiments, beams of H and D atoms are irradiated on the surface of an amorphous silicate sample. The desorption rate of HD molecules is monitored using a mass spectrometer during a subsequent TPD run. The results are analyzed using rate equations, and the energy barriers of the processes leading to molecular hydrogen formation are obtained from the TPD data. We show that a model based on a single isotope provides the correct results for the activation energies for diffusion and desorption of H atoms. These results are used in order to evaluate the formation rate of H2 on dust grains under the actual conditions present in interstellar clouds. It is found that, under typical conditions in diffuse interstellar clouds, amorphous silicate grains are efficient catalysts of H2 formation when the grain temperatures are between 9 and 14 K. This temperature window is within the typical range of grain temperatures in diffuse clouds. It is thus concluded that amorphous silicates are good candidates to be efficient catalysts of H2 formation in diffuse clouds.     

Analytical Assessment of Bioelements in Various Types of Black Teas from Different Geographical Origins in View of Chemometric Approach

A comprehensive approach to the mineral composition of black teas of different origins was studied using the Flame Atomic Absorption Spectrometry (FAAS) method, supported by chemometric tools including Principal Component Analysis PCA) and Classification and Regression Trees (CART). Significant differences between the teas from seven countries (Japan, Nepal, Kenya, Iran, Sri Lanka, India, and China) were shown. K was the main element determined in all teas, with an average concentration of 11,649 mg/kg, followed by Ca, Mg and Mn. In general, regarding all investigated black teas, the element content was ranked in the following order: K > Ca > Mg > Mn > Fe > Na > Zn > Cu. The applied chemometric methods allowed us to recognize black tea clusters based on their mineral composition and place of cultivation, and allowed us to find correlations between particular elements in black teas. The performed analyses revealed interesting correlations between the concentration of various elements in black teas: K was negatively correlated with Na, Fe, Mn and Cu; K was positively correlated with the content of Ca and Mg. Significant positive correlations between Mn and Fe and Mn and Zn in the studied black tea samples were also revealed. It was shown that mineral composition may be a significant factor regarding the origin of the black tea, not only considering the country, but also the region or province.     

On the Hahn-Banach Theorem in Certain Linear Quasi-uniform Structures

A Hahn-Banach type theorem in the frame of quasi-normed spaces (a class of linear spaces with a quasi-uniform structure that contains all linear lattices) is given. The classical result for positive functionals follows as a particular case.     

Three Redox States of Nitrosyl: NO+, NO., and NO−/HNO Interconvert Reversibly on the Same Pentacyanoferrate(II) Platform

Not so elusive : [Fe^II(CN)₅(HNO)]^3? has been characterized spectroscopically after the two‐electron reduction of nitroprusside (see scheme). The complex is stable at pH 6, slowly decomposing to [Fe(CN)₆]^4? and N₂O. It is deprotonated at increasing pH value with oxidation of bound NO^? to [Fe^II(CN)₅(NO)]^3?. [Fe^II(CN)₅(HNO)]^3? is the first non‐heme iron–nitroxyl complex prepared in aqueous solution that is reversibly redox‐active under biologically relevant conditions.

     

Dimeric (isoquinoline)(N‐salicylidene‐d,l‐glutamato)copper(II) ethanol solvate

The title racemic complex, bis[μ‐N‐(2‐oxidobenzylidene)‐d ,l ‐glutamato(2−)]bis[(isoquinoline)copper(II)] ethanol disolvate, [Cu₂(C₁₂H₁₁NO₅)₂(C₉H₇N)₂]·2C₂H₆O, adopts a square‐pyramidal Cu^II coordination mode with a tridentate N‐salicylideneglutamato Schiff base dianion and an isoquinoline ligand bound in the basal plane. The apex of the pyramid is occupied by a phenolic O atom from the adjacent chelate molecule at an apical distance of 2.487 (3) Å, building a dimer located on the crystallographic inversion center. The Cu...Cu spacing within the dimers is 3.3264 (12) Å. The ethanol solvent molecules are hydrogen bonded to the dimeric complex molecules, forming infinite chains in the a direction. The biological activity of the title complex has been studied.