Quantum aspects of torsional vibrations in the HO3H, DO3H and DO3D molecules.

The hydrogen trioxide (HT) molecule HOOOH is 1) a prototype for a class of molecules of the form X(ZY)2 with two equivalent internal tops (ZY) and 2) the second representative of the polyoxides series of the form HOnH (n ≥ 2). Due to this, it is the subject of close attention of researchers. In this paper, we performed a group theory analysis of the torsional and spin states of the HOOOH, DOOOH, and DOOOD molecules. The relationships have been established between the symmetry species of the C2V(M) molecular symmetry group to which the HOOOH and DOOOD molecules belong, and the symmetry species of the C2 and CS point groups to which the equilibrium configurations of trans- and cis-conformers of the above molecules belong, respectively. 2D PES and 2D surfaces of kinematic coefficients related to torsional vibrations of hydroxyl groups were calculated at the complete basis set (CBS) limit by extrapolating the results of calculations at the MP2/cc-pVTZ and MP2/cc-pVQZ levels of theory. For all the three molecules, the energies of the stationary torsional states were computed using the Fourier method for a numerical solution of the 2D vibrational Schrödinger equation. Symmetry species of torsional states and the values of quantum numbers defining the types of torsional vibrations were found by analyzing the torsional wave functions. The selection rules for transitions between torsional states in the dipole approximation were also formulated.

Raman spectroscopic and theoretical study of liquid and solid water within the spectral region 1600-2300cm-1.

Raman spectra of liquid water and ice were measured at different temperatures. The intensity of the band assigned to bending vibrations of water molecules was observed to decrease at the liquid-to-solid transition, while the Raman line near 2200cm-1 showed an anomalously high intensity in the solid phase. A tetrahedral model was used for computer analysis of the observed spectral changes. Quantum-chemical calculations of the structure, normal vibrations and Raman spectra in the harmonic approximation, as well as frequencies and intensities of some vibrations using 1D and 2D potential energy surfaces, were carried out using B3LYP with the cc-pVTZ basis set. The influence of the number of hydrogen bonds on the frequency and Raman activity of the bending vibrations was analyzed. The possibility of hydrogen bond weakening upon excitation of the combined bending-rocking vibration due to the large amplitude of this vibration is considered.

Trace cobalt speciation in bacteria and at enzymic active sites using emission Mössbauer spectroscopy.

57Co emission Mössbauer spectroscopy (EMS) allows the chemical state of cobalt, as influenced by its coordination environment, to be monitored in biological samples at its physiological (trace) concentrations. To draw attention to EMS as a valuable tool for speciation of cobalt in biocomplexes, the process of cobalt(II) metabolism in cells of the plant growth-promoting rhizobacterium Azospirillum brasilense Sp245 was investigated using EMS of 57CoII-doped bacterial cells. EMS measurements also showed 57CoII-activated glutamine synthetase (GS, a key enzyme of nitrogen metabolism, isolated from this bacterium) to have two different cobalt(II) forms at its active sites, in agreement with data available on other bacterial GSs. Chemical after-effects following electron capture by the nucleus of the parent 57CoII during the 57Co-->57Fe transition, which contribute to the formation of a stabilised daughter 57FeIII component along with the nucleogenic 57FeII forms, are also briefly considered.

[Electrooptical properties of soil nitrogen-fixing bacterium Azospirillum brasilense: effect of copper ions]. / Elektroopticheskie svoistva kletok pochvennoi azotfiksiruiushchei bakterii Azosporillum brasilense: vliianie ionov medi.

The effects of copper ions on the uptake of some essential metals in the biomass and the electrooptical properties of cell suspensions of the nitrogen-fixing soil bacterium Azospirillum brasilense sp. 245 were studied. Copper cations were shown to be effectively taken up by the cell biomass from the culture medium. The addition of copper ions increased the rate of uptake of some other metals present in the culture medium. This was accompanied by changes in the electrooptical characteristics of cell suspension as measured within the orienting electric field frequency range of 10 to 10,000 kHz. The effects observed during short-term incubation of A. brasilense in the presence of copper cations were less significant than during long-term incubation. These results can be used for rapid screening of microbial cultures for enhanced efficiency of sorption and uptake of metals.

Influence of divalent cations on the catalytic properties and secondary structure of unadenylylated glutamine synthetase from Azospirillum brasilense.

Fully unadenylylated glutamine synthetase (GS) from the endophytic bacterium Azospirillum brasilense Sp245 was isolated and purified. The enzyme was electrophoretically homogeneous and contained strongly bound metal ions, which could not be removed by dialysis. Mn2+, Mg2+, and Co2+ were found to be effective in supporting biosynthetic activity of the A. brasilense GS. Some kinetic properties of Mn2+-activated and Mg2+-activated unadenylylated GS were characterized. Circular dichroism analysis of the enzyme showed that the A. brasilense GS is a highly structured protein: 59% of its residues form alpha-helices and 13% beta-strands. Removal of the metal ions from the A. brasilense GS by treatment with EDTA resulted in alterations in the enzyme secondary structure.

Chemical and biological parameters as tools to evaluate and improve heavy metal phytoremediation.

In this review, chemical and biological parameters are discussed that strongly influence the speciation of heavy metals, their availability to biological systems and, consequently, the possibilities to use bioremediation as a cleanup tool for heavy metal polluted sites. In order to assess heavy metal availability, a need exists for rapid, cost-effective systems that reliably predict this parameter and, based on this, the feasibility of using biological remediation techniques for site management and restoration. Special attention is paid to phytoremediation as an emerging technology for stabilization and remediation of heavy metal pollution. In order to improve phytoremediation of heavy metal polluted sites, several important points relevant to the process have to be elucidated. These include the speciation and bioavailability of the heavy metals in the soil determined by many chemical and biological parameters, the role of plant-associated soil microorganisms and fungi in phytoremediation, and the plants. Several options are described how plant-associated soil microorganisms can be used to improve heavy metal phytoremediation.

[Destruction of chlorinated derivatives of phenol: ortho-chlorophenol, para-chlorophenol, and 2,4-dichlorophenoxyacetic acid by bacteria communities in anaerobic sludge]. / Destruktsiia khlorproizvodnykh fenola: orto-chlorfenola, para-chlorofenola i 2,4-dikhlorfenoksiuksusnoi kisloty bakteral'nym soobshchestvom anaérobnogo ila.

The bacterial community of anaerobic sludge could degrade ortho-chlorophenol, para-chlorophenol, and 2,4-dichlorophenoxyacetic acid at concentrations as high as 100 mg/l. The time needed for the degradation of a given chlorinated phenol derivative increased 1.5- to 2-fold upon a twofold increase in its concentration (from 50 to 100 mg/l). The duration of the adaptation period depended on the compound studied and on its concentration. The degradation of 2,4-dichlorophenoxyacetic acid proceeded via 2,4-dichlorophenol and p-chlorophenol as intermediates; the degradation of o-chlorophenol occurred with the formation of phenol. The dynamics of p-chlorophenol degradation and chloride ion accumulation were studied.

Mössbauer spectroscopic study of the interaction of indole-3-acetic acid with iron(III) in aqueous solution.

The data of Mössbauer spectroscopic measurements in rapidly frozen 57FeIII nitrate solutions containing indole-3-acetic acid (IAA) are presented. The results obtained provide direct evidence that iron(III) is gradually reduced by IAA with the formation of soluble iron(II) complex. It has been found that further drying of the solution in air results in complete re-oxidation of iron(II) with the formation of iron(III) complex. The structure of the complexes obtained and their possible role in solubilization and transformation of iron species in soil in the presence of IAA secreted by soil microorganisms into the environment are also discussed.

Spectroscopic characterization of the uptake of essential and xenobiotic metal cations in cells of the soil bacterium Azospirillum brasilense.

The results of flame (FAAS) or graphite furnace atomic absorption spectrometric (GFAAS) analyses are presented and discussed on the accumulation of essential metals (Mg, Ca, Mn and Fe contained in the cultivation medium) and traces of each one of the conventionally xenobiotic elements from the group V, Co, Ni, Cu, Zn or Pb, added to the medium in concentrations (0.2 mM) which do not essentially suppress growth of the bacterial culture, in cells of the plant root-associated nitrogen-fixing bacterium Azospirillum brasilense. Along with the essential cations assimilated by the bacterium, Zn and Cu were found to effectively accumulate in the biomass from the environment. The uptake of Co and Ni was significantly less pronounced, whereas Pb and V appeared to be present in cells in much lower concentrations than in the cultivation medium evidently showing no tendency to be assimilated by azospirilla. The effect of the above xenobiotics on the uptake level of the four essential elements provided evidence that they may compete for the formation of biologically active complexes with substances of both intracellular and extracellular localization. The analytical data obtained are compared with Fourier transform infrared (FTIR) spectra of intact vacuum-dried bacterial cells grown in a standard medium and under the conditions of an increased metal uptake.

Spectroscopic study of nickel(II) hydroxide surface modifications induced by a small iron(III) addition.

Comparative Auger electron spectroscopic data on the surface composition and depth profiling for beta-Ni(OH)(2) and Ni(OH)(2) coprecipitated with iron(III) (3 at.%) are given showing a non-uniform distribution of the latter. They are considered together with their structural characteristics obtained using Fourier transform infrared spectroscopy (both samples) and Mössbauer spectroscopy (Fe-containing sample). The results obtained provide an explanation for the specific behaviour of the Fe(III)-doped nickel(II) hydroxide in heterogeneous processes (adsorption, electrocatalysis).

Spectroscopic characterization of mineral crystals produced by the bacterium Azospirillum brasilense.

The results of spectroscopic structural and trace elemental analyses of mineral crystals produced by the soil nitrogen-fixing bacterium Azospirillum brasilense cultivated in a synthetic medium are presented and discussed. The mineral formed is shown to have a structure close to struvite (MgNH(4)PO(4) x 6H(2)O; ASTM file No. 15-762) with some differences which may be attributed to the presence of isomorphic admixtures of other cations (struvite is known to have a variety of forms). AAS/AES and ion chromatography analyses for a number of biologically important microelements and their role in the formation of the crystal structure, as well as some questions related to biomineralization are also discussed.