Pre-Pegmatite Stage in Peralkaline Magmatic Process: Insights from Poikilitic Syenites from the Lovozero Massif, Kola Peninsula, Russia

The Lovozero peralkaline massif (Kola Peninsula, Russia) is widely known for its unique mineral diversity, and most of the rare metal minerals are found in pegmatites, which are spatially associated with poikilitic rocks (approximately 5% of the massif volume). In order to determine the reasons for this relationship, we have investigated petrography and the chemical composition of poikilitic rocks as well as the chemical composition of the rock-forming and accessory minerals in these rocks. The differentiation of magmatic melt during the formation of the rocks of the Lovozero massif followed the path: lujavrite → foyaite → urtite (magmatic stage) → pegmatite (hydrothermal stage). Yet, for peralkaline systems, the transition between magmatic melt and hydrothermal solution is gradual. In the case of the initially high content of volatiles in the melt, the differentiation path was probably as follows: lujavrite → foyaite (magmatic stage) → urtitization of foyaite → pegmatite (hydrothermal stage). Poikilitic rocks were formed at the stage of urtitization, and we called them pre-pegmatites. Indeed, the poikilitic rocks have a metasomatic texture and, in terms of chemical composition, correspond to magmatic urtite. The reason for the abundance of rare metal minerals in pegmatites associated with poikilitic rocks is that almost only one nepheline is deposited during urtitization, whereas during the magmatic crystallization of urtite, rare elements form accessory minerals in the rock and are less concentrated in the residual solution.

Chemical composition, antioxidant, antimicrobial activity, toxicity, genetic analysis and popular use of Eugenia luschnathiana(O. Berg) Klotzsch ex B.D.Jacks: a literature review

This review describes the geographical distribution, botanical data, popular use, chemical composition, pharmacological activities and genetic aspects related to Eugenia luschnathiana, a native Brazilian plant popularly known as “bay pitomba”. E. luschnathianaleaves are characterized morphologically by the presence of a petiole, an attenuated base, acuminated apex, elliptical shape, and parallel venation. The major chemical compounds found in E. luschnathiana are sesquiterpenes. Literature reports showed that E. luschnathianaextracts have antioxidant properties and antimicrobial activity against Gram-negative and Gram-positive bacteria. The extractsfrom the leaf, fruit and stem, and a concentrated residual solution of its essential oil, displayed negligible toxicity. Lastly, a cytogenetic analysis indicated that some markers can be used for the study of genetic diversity, population structure, and genetic improvements. The information available on E. luschnathianasupports the hypothesis that this plant may be a source of compounds with promising pharmacological activity.

Synthesis of MgFe Layered Double Hydroxide from Iron-Containing Acidic Residual Solution and Its Adsorption Performance

The paper presents a new method of layered double hydroxide (LDH) synthesis starting from secondary sources, namely acidic residual solutions. The iron content of the acidic solution resulting from the pickling step of the hot-dip galvanizing process make it suitable to be used as an iron precursor in LDH synthesis. Here, Mg4Fe–LDH synthesized through the newly proposed method presented structural and morphological characteristics similar to the properties of layered double hydroxides synthesized from analytical-grade reagents. Moreover, the as-synthesized LDH and its calcined product presented efficient adsorption properties in the removal process of Mo(VI) from aqueous solutions. The adsorption studies are discussed from the equilibrium, kinetic, and thermodynamic points of view. The proposed novel technologies present both economic and environmental protection benefits.

Memory effect in tetra-n-butyl ammonium bromide semiclathrate hydrate reformation: the existence of solution structures after hydrate decomposition

The memory effect in TBAB semiclathrate hydrate reformation results from the residual solution structure composed of clusters and cluster aggregates.

Biosorption of Heavy Metals Using Organic Waste from Tequila Processing

In Mexico and in the world, the metallurgical, petroleum and chemical industries, among others, generate large amounts of pollutants, which when deposited in dams or discharged into rivers, ponds or directly into aquifers generate serious problems for the environment. Biosorption is the phenomenon of passive uptake of metal ions with non-living organic materials, known as biomass, which are generally industrial waste. Active uptake with live biomass is called bioaccumulation. Biosorption is based on the property of some types of inactive or dead biomass to uptake and accumulate these elements by different mechanisms. There are several mechanisms that explain the fixation and retention of metals by the biosorbent used: physical adsorption, ion exchange, complexation, chelation etc. In this work the behavior of three organic residues from the tequila production process at Tarimoro plant, the fiber or bagasse obtained from the must from tequila processing, agave leaves and solid tequila vinasse were evaluated. The tests were carried out by contacting the biomass with a solution containing metal cations such as Cu, Fe and Mn. The maximum adsorption capacity was obtained at a pH of 8 (98% copper adsorption) with agave fiber biomass at temperature of 25°C. The samples studied at temperatures of 25°C showed the lowest concentration values ​​of Cu2+ in residual solution. The adsorption process was found dependent on pH and time. The results obtained allow to affirm that organic wastes from the elaboration of tequila are a viable alternative as biomass in the bioremediation process of toxic heavy metals by a biosorption technique.

The fractionation of nitrogen and oxygen isotopes in macroalgae during the assimilation of nitrate

In order to determine and understand the stable isotope fractionation of 18O and 15N manifested during assimilation of NO3− in marine macro-benthic algae, two species (Ulva sp. and Agardhiella sp.) have been grown in a wide range of NO3− concentrations (2–500 μM). Two types of experiments were performed. The first was one in which the concentration of the NO3− was allowed to drift downward as it was assimilated by the algae, between 24 hour replacements of media. These experiments proceeded for periods of between 7 and 10 days. A second set of experiments maintained the NO3− concentration at a low steady-state value by means of a syringe pump. The effective fractionation during the assimilation of the NO3− was determined by measuring the δ15N of both the (i) new algal growth and (ii) residual NO3− in the free-drift experiments after 0, 12, 24 and 48 h. Modelling these data show that the fractionation during assimilation is dependent upon the concentration of NO3− and is effectively 0 at concentrations of less than ~2 μM. The change in the fractionation with respect to concentration is the greatest at lower concentrations (2–10 μM). The fractionation stablizes between 4 and 6‰ at concentrations of between 50 and 500 μM. Although the δ18O and δ15N values of NO3− in the residual solution were correlated, the slope of relationship also varied with respect to NO3− concentration, with slopes of greater than unity at low concentration. These results suggest shifts in the dominant fractionation mechanism of 15N and 18O between concentrations of 1 and 10 μM NO3−. At higher NO3− concentrations (>10–50 μM), fractionation during assimilation will lead to δ15N values in algal biomass lower than the ambient NO3− and 15N enrichments in the residual NO3−.

The fractionation of nitrogen and oxygen isotopes in macroalgae during the assimilation of nitrate

In order to determine and understand the stable isotope fractionation of 18O and 15N manifested during assimilation of NO3− in marine macro-benthic algae, two species (Ulva sp. and Agardhiella sp.) have been grown in a wide range of NO3- concentrations (2–500 μM). Two types of experiments were performed. The first was one in which the concentration of the NO3− was allowed to drift downward as it was assimilated by the algae, between 24 h replacements of media. These experiments proceeded for periods of between seven and ten days. A second set of experiments maintained the NO3− concentration at a low steady state value by means of a syringe pump. The effective fractionation during the assimilation of the NO3− was determined by measuring the δ15N of both the (i) new algal growth, and (ii) residual NO3− in the free drift experiments after 0, 12, 24, and 48 h. Fitting models to these data show that the fractionation during assimilation is dependent upon the concentration of NO3− and is effectively zero at concentrations of less than 1 μM. The change in the fractionation with respect to concentration is the greatest at lower concentrations (1–10 μM). The fractionation determined using the δ15N of the NO3− or the solid algal material provided statistically the same result. Therefore, at typical marine concentrations of NO3−, fractionation during assimilation can probably be considered to be negligible. Although the δ18O and δ15N of NO3− in the residual solution were correlated, the slope of the relationship varied with NO3− concentration, with slopes of greater than unity at low concentration. These results suggest shifts in the dominant fractionation mechanism between 1 and 10 μM NO3−. At typical marine concentrations of NO3−, fractionation during assimilation can be considered to be negligible. However, at higher concentrations, fractionation during assimilation will lead to both δ15N values for algal biomass lower than the NO3− source, but also 15N enrichments in the residual NO3−.