Liquid—liquid extraction of metal ions by the sulfide podand 1,12-di-2-thienyl-2,5,8,11-tetrathiadodecane

The sulfide podand (an open-chain neutral mutlidentate ligand with six sulfur donor atoms) 1,12-di-2-thienyl-2,5,8,11-tetrathiadodecane (TTD) was synthesized. Its extracting properties were examined with 1,2-dichloroethane and 4-methylpentan-2-one as solvents. The reagent showed high selectivity for silver(I) and copper(I) ions; mercury(II) was extracted (ca. 97%) under certain conditions. Extraction of silver(I) was studied in detail with ^110mAg tracer. Log D values ?2 were obtained for the range from pH 6 (with perchlorate as counter-ion) to 2 M perchloric acid or 6 M nitric acid. The ratio of Ag:TTD in the complex was 1:1. Silver could be back-extracted with 4–6 M hydrochloric acid.     

Flotation method for separation of elemental Te with Se as collector

Summary A method combining co-precipitation of traces of elemental Te on Se as carrier with organic solvent flotation is described. The best reduction and flotation conditions (hydrochloric and phosphinic acid concentrations, amount of Se, solvent used) were chosen. The recoveries for 100g of Te(IV) (AAS measurement in MIBK) and 2g of Te (radiochemical measurement with¹²⁷Te) were 98% and 84–88%. The method was applied for separation of Te(IV) from copper metallurgy dust and slag.

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Flotationsverfahren zur Abtrennung von elementarem Tellur mit Selen als Kollektor

Zusammenfassung Die Kombination der Mitfällung von Spuren elementaren Tellurs auf Selen als Trägersubstanz mit der Flotation mit Hilfe eines organischen Lösungsmittels wurde beschrieben. Die besten Bedingungen zur Reduktion und Flotation (Salzsäure-und Phosphinsäurekonzentration, Selenmenge, Lösungsmittel) wurden ausgewählt. Die Wiederfindungsraten für 100g Te(IV) (AAS-Bestimmung in MIBK) und 2g Te (radiochemische Messung mit¹²⁷Te) waren 98% bzw. 84–88%. Das Verfahren wurde zur Trennung von Te(IV) aus dem Staub und der Schlacke der Kupfermetallurgie verwendet.

     

Synthesis of polyetherols with isocyanuric ring. Kinetics and mechanisms of reactions,part 1: Reaction between isocyanuric acid and ethylene carbonate

The reaction between isocyanuric acid and ethylene carbonate results in the formation of polyetherols. The kinetic and mechanistic studies revealed that the initial step of the reaction is zero order related to ethylene carbonate. The rate‐limiting step is the decomposition of an intermediating dianion of ethylene dicarbonate into ethane‐1,2‐diolate dianion and carbon dioxide. Imide groups of isocyanuric acid inhibit the reaction. The mechanism of reaction was confirmed by spectroscopic methods. © 2009 Wiley Periodicals, Inc. Int J Chem Kinet 41: 512–522, 2009     

Effect of Gd and Fe doping on magnetic properties of Al87Y5Ni8 amorphous alloy

In this paper we present and discuss magnetic properties of the Al₈₇Y₅Ni₈, Al₈₇Y₄Gd₁Ni₈, Al₈₇Gd₅Ni₈, Al₈₇Y₄Gd₁Ni₄Fe₄ and Al₈₇Gd₅Ni₄Fe₄ amorphous alloys. The examinations have been concentrated on a possible magnetic ordering at low temperatures and its modification by amorphous surroundings as well as different magnetic moment of alloying additions. It was shown that magnetic properties of the Al₈₇Y₅Ni₈ amorphous base alloy correspond to a superparamagnetic body with Ni magnetic clusters. Magnetic moment of Ni atom in amorphous aluminum matrix is found to be 0.3 μ_B that corresponds to less than 50 Ni atoms per one cluster. Gd doping of the base alloy leads to a decrease of the resultant magnetic moment of Ni clusters that can be explained by some antiferromagnetic coupling Ni-Gd and Ni-Ni within magnetic clusters.     

Fast broadcasting and gossiping in radio networks

We establish an O(nlog²n) upper bound on the time for deterministic distributed broadcasting in multi-hop radio networks with unknown topology. This nearly matches the known lower bound of Ω(nlogn). The fastest previously known algorithm for this problem works in time O(n^3/2). Using our broadcasting algorithm, we develop an O(n^3/2log²n) algorithm for gossiping in the same network model.     

Topical Administration of Terpenes Encapsulated in Nanostructured Lipid-Based Systems

Terpenes are a group of phytocompounds that have been used in medicine for decades owing to their significant role in human health. So far, they have been examined for therapeutic purposes as antibacterial, anti-inflammatory, antitumoral agents, and the clinical potential of this class of compounds has been increasing continuously as a source of pharmacologically interesting agents also in relation to topical administration. Major difficulties in achieving sustained delivery of terpenes to the skin are connected with their low solubility and stability, as well as poor cell penetration. In order to overcome these disadvantages, new delivery technologies based on nanostructures are proposed to improve bioavailability and allow controlled release. This review highlights the potential properties of terpenes loaded in several types of lipid-based nanocarriers (liposomes, solid lipid nanoparticles, and nanostructured lipid carriers) used to overcome free terpenes’ form limitations and potentiate their therapeutic properties for topical administration.     

Vindoline and 16‐de­methoxy­vin­doline: two catharanthus‐derived alkaloids

Vindoline, C₂₅H₃₂N₂O₆, and 16‐de­methoxy­vindoline, C₂₄H₃₀N₂O₅, both of which are naturally occurring biologically active products derived from plants, are important as possible starting materials for the synthesis of valuable anticancer antibiotics, viz. vincristine and vinblastine, and other pharmaceuticals. The vindoline framework consists of two five‐ and three six‐membered condensed rings. One of the six‐membered rings adopts a boat conformation, one adopts a sofa conformation and the third is planar. Both five‐membered rings have envelope structures. The intramolecular hydrogen bonds present in the structures are characteristic of vinca alkaloids.     

Long-term stability of soft magnetic properties of amorphous and nanocrystalline alloys based on iron

In the present paper long-term stability of magnetic properties of different amorphous and nanocrystalline alloys was studied. Magnetic properties were measured for annealed samples (300<Ta<900 K) directly after annealing and after long-term aging at room temperature. It was shown that for the Fe_75.3Cu₁Zr_1.7Si₁₃B₉ alloy magnetic permeability of the optimized samples is stable during 8 years aging. For Fe_86−xNb_xB₁₄ alloys the observed long-term instability (3 years aging) is due to annealing out of free volume leading to formations of small iron clusters coherent with the amorphous surroundings.