Interaction of heavy metal ions with ammonium humates

Sorption properties of ammonium humates with respect to Fe(III), Cu(II), Al(III), Ni(II), Pb(II), and Zn(II) are studied. The effect of the metal ion concentration on the ammonium humate consumption is examined and the corresponding dependences are analyzed using regression equations. The IR spectra of brown coal humic acids, ammonium humates, as well as Fe, Cu, Ni, Zn, Pb, and Al humates are presented.     

Alkaline hydrolysis of the natural lignin of cottonplant stems in the presence of anthraquinone

The study of a three-stage alkaline hydrolysis of the natural lignin of cottonplant stems has shown that the bulk of the lignin undergoes fragmentation during stage I. The addition of anthraquinone leads to an appreciable increase in the yield of low-molecular-mass hydrolysis products.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Republic of Uzbekistan, Tashkent, fax (3712) 89 14 75. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 743–748, September–October, 1996. Original article submitted March 1, 1993.     

Overlapping spheres multiple scattering Xα calculations of the ionization potentials and electron affinities of nitrogen oxides

The ionization potentials and electron affinities of a series of nitrogen oxygen compounds have been calculated by the overlapping spheres MS Xα method to assess its applicability on a series for which good experimental data is available. The results for the ionization potentials were satisfactory although a straightforward matching of calculated and experimental IP's without consideration of other criterion would have led to some misassignments. The results for the electron affinities are in excellent agreement with experiment.     

On low temperature fluorescence of perylene crystals

At low temperatures, the broad excimer fluorescence band of α-perylene crystals is replaced by a weakly structured emission at higher energy. This emission originates from a new crystal state (Y-state) which is populated independently of the high temperature excimer (E-state). Due to the temperature dependence of its first order decay rate and due to the thermally activated formation of the E-state, the Y-emission grows rapidly at temperatures below 90 K. The Y-emission differs from the fluorescence of the monomeric β-perylene at 5.5 K by its Stokes shift of 1300 cm^?1, the lack of vibronic structure, the long first order decay time of 40 ns and the absence of bimolecular annihilation indicating a localized state. The Y-state is attributed to a less relaxed pair state formed upon contraction of the dimeric crystal lattice.     

Synthese und Röntgenstrukturanalyse des 8π-Elektronenringsystems S4N4O2Sn2(CH3)6 und des magnetische Verhalten von S4N4O2 und S8N8O4

Synthesis and X-Ray Structure Analysis of the 8π-Electron-Ring-System S₄N₄O₂Sn₂(CH₃)₆ and the Magnetic Properties of S₄N₄O₂ and S₈N₈O₄ S₄N₄O₂ reacts with N[Sn(CH₃)₃]₃ in a molar ratio of 1:1 to an eight-membered trimethyltin-substituted 8π-electron skeleton, S₄N₄O₂Sn₂(CH₃)₆. In contrast to known 6π-electronsystems this compound has tin atoms which are tetracoordinated. This was demonstrated on the basis of an x-ray analysis. S₄N₄O₂Sn₂(CH₃)₆ · 1/2 C₆H₆ crystallizes in the space group P2₁/c with a = 1396.0(4), b = 1190.3(4), c = 1256.7(3) pm, and β = 103.46(2)°. It was shown that the ability of coordination at the tin atom depends on the electron density. The magnetic properties of S₄N₄O₂ and S₈N₈O₄ were investigated by the Faraday method. The high diamagnetism in these ring compounds is caused by the π-electrons.     

Automation of the gas analysis of14C-labelled compounds utilizing a piston-type counter tube

In this paper an automatic apparatus designed for the radioactivity measurement of¹⁴C-labelled organic compounds in the gaseous phase is described. The labelled organic compounds are combusted in a mixture of argon and oxygen. After combustion the oxygen content of the gas is eliminated by passing it through a copper packing. The water and heteroelements present are also removed and the radioactive carbon dioxide gas is swept by argon carrier gas into a piston-type counter tube. In the counter tube the piston forming a dividing wall moves forward in accordance with the rate of combustion and sweeping, and thus sucks the gases leaving the combustion tube into the effective tube volume. The anode wire is carried by a reel located in the piston and a spring device ensures its stretched state. At the end of the sweeping period methane is fed into the counter tube and the activity of the argon—methane—carbon dioxide mixture is measured in the limited proportional region. Manual and automatic operation is possible. The piston-type counter tube provides possibility for strandardization by means of extrapolation and for measurement of absolute activities.     

Random peptide synthesis using immobilized enzymes in high concentrations of organic solvents

Trypsin, leucine aminopeptidase, and carboxypeptidase B were separately immobilized on controlled pore glass and reacted with a dipeptide substrate in high concentrations of either acetone or 1-propanol. Hydrolytic activity was demonstrated and evidence for the possible synthesis of peptide polymer is presented. Directed synthesis using amino acids and blocked amino acids as substrates was not successful.     

Optically detected zero-field triplet state magnetic resonance in photosynthetic bacteria

Triplet state transitions of the photosynthetic bacteria Rhodospirillum Rubrum, Rhodopseudomonas Spheroides and Chromatium Vinosum in chemically reduced preparations have been observed by zero-field optical detection of magnetic resonance at 2 K. For each bacterial preparation two sharp, structureless, zero-field EPR transitions were observed as microwave-induced decreases in the fluorescence intensity of the frozen cellular preparations. The depopulating rate constants for the spin sublevels of the triplet states observed in R Rubrum and R Spheroides were also measured. The similarities of the triplet state frequencies, spectral features and intersystem crossing rates suggest a common structure for the reaction centers in the photosynthetic bacteria.     

A study of the process of lignification of one-year willow wood

Conclusions 1. The content of lignin in the wood ofSalix viminalis andSalix acutifolia increases with the growth of the shoots during shortened days and also in drier climatic periods.2. The monosaccharides, glucose, fructose, and arabinose take part in the synthesis of the lignin of young wood ofSalix viminalis andSalix acutifolia. The formation of lignin of one-year willow wood takes place from May to January (with a maximum in June–July). The content of methoxyl groups in it gradually rises.Khimiya Prirodnykh Soedinenii, Vol. 5, No. 6, pp. 546–550, 1969