Chemical fate of iron in a peatland developing in the southern Espinhaço chain,Brazil

A peatland (geographical coordinates of the sampling site, 18° 05′ 43.6″ S, 43° 47′ 6.4″ W; altitude 1,330 m asl) in São João da Chapada, municipality of Diamantina, state of Minas Gerais, was sampled at different depths of two profiles with different vegetation coverings (namely, field grassland and bush) in order to collect materials that might reflect changes of the chemical states of iron over the peat formation coming from original minerals like basic rock very likely influenced by hematitic phyllite surrounding the boggy pedon. Mössbauer spectroscopy spectra at room temperature and chemical composition analysis reveal that the iron contents for the peatlands under both vegetations decreases on going from the surface downwards. Also, a central doublet of (super)paramagnetic ferric chemical species, even for samples from deeper positions on the profile, where the reducing chemical potential of the pedoenvironment is thought to be higher, dominates the spectral patterns for all samples. In agreement with the Mössbauer results, magnetic measurements give evidence that the magnetic response of the surface samples is the highest, displaying a sharp decrease below 15 cm and a slight but steady increase with depth down along the profile.     

Quantum chemical properties investigation and molecular docking analysis with DNA topoisomerase II of β-carboline indole alkaloids from Simaba guianensis: a combined experimental and theoretical DFT study

Structural Chemistry - A theoretical and experimental DFT study of the vibrational, structural, and quantum properties of 9-methoxy-canthin-6-one (I) and...     

Novel green strategy to improve the hydrophobicity of cellulose nanocrystals and the interfacial elasticity of Pickering emulsions

The development of Pickering emulsions as ecologically correct stabilized with bio-based material by substituting synthetic petroleum-derived tensoactives assumed a very attractive level, representing the current guideline of the global market for homecare industry, food and beverage applications. In this wor, cellulose nanocrystals (CNCs), a hierarchically advanced biomaterial, were produced to stabilize innovative emulsions formulated with western soapberry Sapindus saponaria L. oil (SO). Besides, green surfactants (triterpene saponins extracted from S. saponaria L. pericarp; SAP) were also investigated to stabilize the oil/water interface. The synergistic combination between cellulose nanowhiskers and the bioactive glycosides has never been reported in the literature. Dynamic interfacial tensions of SAP and SO were firstly investigated, and their capacity to form a plastic membrane at oil/water interface was revealed. Response surface methodology (RSM) was employed to study the influence of the binary systems (CNC:SAP) on the stability of emulsified systems, such as size and zeta potential. In addition, a new calculation was proposed to determine the coverage of the oil droplets formed by the mixture of cellulose crystallites and natural surfactants. The optimal nanoemulsion composition was determined to be 60 w/w (%) of water, 23.905 w/w % of SO, 5 w/w % of CNC and 8.095 w/w% of SAP to produce of smallest droplet (165.1 nm) combined with higher zeta potential module (?46.7 mV). Results highlight the potential of Sapindus saponins and cellulose nanowhiskers for efficient producing label-friendly nanoemulsions applicable for drug, cosmeceutical or edible delivery systems.

Graphical abstract

     

Reduction Methods for Total Reaction Cross Sections

The most frequently used methods to reduce fusion and total reaction excitation functions were investigated in a very recent paper Canto et al. (Phys Rev C 92:014626, 2015). These methods are widely used to eliminate the influence of masses and charges in comparisons of cross sections for weakly bound and tightly bound systems. This study reached two main conclusions. The first is that the fusion function method is the most successful procedure to reduce fusion cross sections. Applying this method to theoretical cross sections of single channel calculations, one obtains a system independent curve (the fusion function), that can be used as a benchmark to fusion data. The second conclusion was that none of the reduction methods available in the literature is able to provide a universal curve for total reaction cross sections. The reduced single channel cross sections keep a strong dependence of the atomic and mass numbers of the collision partners, except for systems in the same mass range. In the present work we pursue this problem further, applying the reduction methods to systems within a limited mass range. We show that, under these circumstances, the reduction of reaction data may be very useful.