Polarographic studies on the complexation of cobalt(II), nickel(II) and copper(II) withd-glucosamine andd-galactosamine

D.c. polarography was used to establish the equilibria existing in Cu(II), Ni(II) and Co(II) systems with d-glucosamine and d-galactosamine. The results clearly indicated the formation of 1:1 complexes, ML, and allowed calculation of the stability constants of some complexes. The present results completed very well the potentiometric and spectroscopic data obtained earlier. The reduction mechanisms and the electrochemical behaviour of the formed complexes were also established.     

New SRDN-3 probes with a semi-conductor detector for measuring radon activity concentration in underground spaces

The article presents new Polish probes SRDN-3, developed at the Institute of Nuclear Chemistry and Technology in Warsaw, equipped with a semi-conductor detector used for continuous measurements of ²²²Rn activity concentration. Due to a relatively high lower detection limit, the device is dedicated for use in underground spaces—caves, adits, mines, tourist routes in strongholds, pyramids, etc. Its structure allows for difficult conditions in which the device is transported to the measurement site, as well as hard operating conditions caused chiefly by large ambient relative humidity, reaching up to 100%. The authors present calibration results of these appliances, as well as the results of their work in a cave and an adit in the Sudetes (SW Poland). After almost 2 years of working in difficult conditions, the probes displayed high reliability. No defects of the semi-conductor detectors or the electronics were observed, which ensured problem-free communication of the probe-programmer-PC set. Thanks to this, the authors have a 2 year stock of data, recorded hourly by five probes, at their disposal. The only element that did not withstand the test of extreme operating conditions was one of the combined relative humidity and temperature sensors. No powering problems were observed either, and the batteries were replaced once a year, before the winter season. Also the programmer functioned faultlessly, enabling data transmission to a PC, which, being much more sensitive to operating conditions, had been placed away from the site of probe exposure. After using more sensitive temperature, relative humidity and pressure sensors, SRDN-3 probes will certainly prove an excellent tool for microclimate measurements (including measurement of air-atmosphere exchange) in caves and other underground sites. Even nowadays they are already a satisfactory tool for monitoring ²²²Rn concentration in underground spaces.     

Synthesis and Structural Analysis of Higher Analogs of Sucrose

ABSTRACT

Three sucrose monoalcohols with free hydroxyl groups at C-1', C-6, and C-6' (1, 4, and 6) were prepared selectively and in good yield from 2,3,3',4,4'-penta-O-benzylsucrose. These compounds were oxidized to aldehydes and reacted with stabilized ylide, Ph₃P=CHCO₂Me to afford appropriate α,β-unsaturated esters 10, 11, and 12. Each olefin was cis-hydroxylated with OsO₄/NMO to stereoisomeric diols 13/14, 15/16, and 17/18, configurations of which were assigned by chemical correlation and CD evaluation. Stereoselectivity of the osmylation reaction was surprisingly low (ca 3:2), especially as compared to a similar process performed on simple derivatives of 6,7-unsaturated methyl glycosides for which the ratio of isomeric diols was assigned as 10:1. The osmylation of 11 (derivative homologated by a C₂-unit at the glucose part) did not obey Kishi's rule. Horner-Emmons reaction of sucrose aldehyde 7 with a sugar-derived phosphonate 22 afforded α,β-unsaturated derivative 24, homologated by a C₇-unit at the glucose end.     

Application of anoxic fixed film and aerobic CSTR bioreactor in treatment of nanofiltration concentrate of real textile wastewater

An anoxic fixed film bioreactor (FFB) with biomass immobilized on activated carbon and an aerobic continuous stirred tank bioreactor with overflow were applied to degrade concentrate from nanofiltration of real textile effluents containing Reactive Red 120 (RR-120). The efficiency of color removal was 99 % irrespective of the fraction of nanofiltration concentrate in the feed. An approximate dye balance based on the assessed adsorption capacity of RR-120 by activated carbon indicated that the dye was removed by means of adsorption as well as of biological processes. Aromatic amine released from a dye molecule was fully adsorbed by activated carbon. COD level in the outflow of the system was above that imposed by legislation. Despite an adjustment of the feed pH to 7 this was constantly increasing up to the value above 9 in both reactors. Neither the nanofiltration concentrate nor the effluents from the bioreactors affected the growth of Pseudomonas putida used as toxicity indicator.     

A charged composite particle in a constant electric field

We consider the motion of a composite charged particle in a constant electric field. Using the billiard formalism, we establish exact laws of motion for such a particle with a small number of internal degrees of freedom and propose using a generalized Schwarz principle to straighten trajectories in the field presence. Within the billiard formalism, we obtain regimes of motion of a composite particle with two internal degrees of freedom in a constant field.     

VPO catalysts synthesized on substrates with modified activated carbons

VPO catalysts were prepared on oxidized and unoxidized activated carbons differing in initial porous structure. Carbons were oxidized under relatively soft (30% H₂O₂, 200 °C) and hard (50% H₂O₂, 350 °C) conditions. Carbon modification was carried out hydrothermally in a traditional autoclave (HTT) or a microwave reactor (MWT). The synthesis was also carried out under hydrothermal (HTS or MWS) conditions. V₂O₅ and NH₄VO₃ were used as precursors. The samples are characterized by diversified porous structure at S_BET = 732-1617 m²/g and V_por = 0.44-0.90 cm³/g, as well as various degree of VPO crystallinity. Possibility of preparation of the VPO catalysts under ecologically appropriate conditions, i.e. in aqueous solutions, was shown.     

New organoelement polyelectrolytes: Protonated poly(alkylaminophosphazenes)

The organoelement polymer bases poly(methylaminophosphazene) and pol(ethylaminophosphazene) have been synthesized by the solid-phase aminolysis of linear ultrahigh-molecular-weight poly(dichlorophosphazene) and characterized. The related cationic polyelectrolytes have been prepared in aqueous solutions in the presence of HCl. As exemplified by the interaction with sodium polystyrenesulfonate and sodium polyphosphate, the polymers form interpolyelectrolyte complexes with anionic polyelectrolytes.     

Performance of DFT in modeling electronic and structural properties of cobalamins

Computational modeling of the enzymatic activity of B12-dependent enzymes requires a detailed understanding of the factors that influence the strength of the Co--C bond and the limits associated with a particular level of theory. To address this issue, a systematic analysis of the electronic and structural properties of coenzyme B12 models has been performed to establish the performance of three different functionals including B3LYP, BP86, and revPBE. In particular the cobalt-carbon bond dissociation energies, axial bond lengths, and selected stretching frequencies have been analyzed in detail. Current analysis shows that widely used B3LYP functional significantly underestimates the strength of the Co--C bond while the nonhybrid BP86 functional produces very consistent results in comparison to experimental data. To explain such different performance of these functionals molecular orbital analysis associated with axial bonds has been performed to show differences in axial bonding provided by hybrid and nonhybrid functionals.     

Birkhoff‐Frink representations as functors

In an earlier article we characterized, from the viewpoint of set theory, those closure operators for which the classical result of Birkhoff and Frink, stating the equivalence between algebraic closure spaces, subalgebra lattices and algebraic lattices, holds in a many‐sorted setting. In the present article we investigate, from the standpoint of category theory, the form these equivalences take when the adequate morphisms of the several different species of structures implicated in them are also taken into account. Specifically, our main aim is to provide a functorial rendering of the Birkhoff‐Frink representation theorems for both single‐sorted algebras and many‐sorted algebras, by defining the appropriate categories and functors, covariant and contravariant, involved in the process (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Photodegradation Products of New Dihydropyridine Derivatives

Photodegradation of two dihydropyridine compounds has been studied in accordance with the recommendations of the first version of the ICH guidelines. Photodecomposition was monitored by UV–visible spectroscopy, LC, and LC–MS. Quantum yields and kinetic data were obtained for the photochemical reactions. The new dihydropyridine derivatives were found to decompose into different numbers of photoproducts with different rate constants. The derivative with two chlorine atoms in the phenyl ring proved to be more stable than the nitro derivative.