A new representative of sterically hindered 3,6-di-
tert
-butyl-
o
-benzoquinones bearing an annulated tetrahydrooxazolo3,2-
d
1,4oxazine moiety—6,9-di-
tert
-butyl-1,2,3
a
,4-tetrahydrobenzo
b
...oxazolo3,2-
d
1,4oxazine-7,8-dione—was synthesized. The structure of the novel compound was confirmed by IR, UV, and NMR spectroscopy and X-ray diffraction. According to the cyclic voltammetry, the first reduction potential of the quinone in acetonitrile is –0.83 V (Ag/AgCl/KCl reference electrode).
The chemical and isotopic characteristics (δ
18
O and δ
2
H) of water from 42 mud volcanoes of the Kerch–Taman region (Crimean–Caucasus district) were analyzed. The formation temperatures of mud ...volcanic waters were estimated using the Mg-Li hydrochemical geothermometer (t(Mg-Li) = 40–134°C). It was revealed that dehydration waters released during the smectite–to-illite transformation play significant role in the total fluid balance of the mud volcanic systems (up to 80% of the total fluid volume). These waters are characterized by low Cl ion contents, δ
18
O from +13 to +17‰, and δ
2
H from –25 to –20‰ relative to VPDB, and high concentrations of
, B, Li, Ba and other trace elements. Correlations between the concentration of HCO
3
, B, δ
18
O, and t(Mg-Li) values were revealed.
The chemical and isotopic signatures of mud volcanic fluids were determined for 42 mud volcanoes of the Kerch–Taman region (Crimea–Caucasus district). The analysis of spatial geochemical trends of ...mud-volcanic waters and gases and estimates of formation temperatures using the Mg–Li geothermometer allowed us to attribute the mud volcanic fluids to sediments of the Maikop Formation, the thickness of which in the studied region varies from 1 to 5–6 km. It was shown that an increase of CO
2
and
concentrations and values of δ
18
O in H
2
O and δ
13
C in CH
4
, as well as a decrease of Cl
–
concentrations and δ
13
C values in
and CO
2
correlate with increasing thickness of the Maikop sediments in the central part of the Kerch–Taman region. At the periphery of this region, in the foothills of the Caucasus and Crimea orogens, this correlation is absent. Active tectonic processes in these areas provided contribution of additional “higher temperature” sources of water and gas to fluids in the mud volcanic systems. Using the Kerch–Taman region gases as an example, it was shown for the first time that the enrichment of mud volcanic fluids in isotopically heavy CO
2
(δ
13
C CO
2
to +22.8‰; δ
13
C HCO
3
to +38.9‰) occurs within a narrow temperature range (40–80°C). At higher temperatures, the accumulation of isotopically heavy CO
2
is ceased. These trends suggest that the high-δ
13
C CO
2
is related to the hydrocarbon biodegradation. Using δ
13
C (in CH
4
and CO
2
) and δ
2
H (in CH
4
) classification, it was shown that at least three methane sources could participate in the CH
4
balance: microbial (primary), connected with “biodegradation” (secondary), and thermogenic. The content of “secondary” methane in some cases can reach almost 100%. In the studied mud volcanic gases, the isotopic composition of molecular nitrogen was determined for the first time. The δ
15
N values vary from –5.2 to –0.1‰ (δ
15
Nav = –2.3 ± 0.9‰,
n
= 35) and indicate a significant admixture of the non-atmospheric nitrogen. A negative correlation between values of δ
15
N in N
2
, δ
13
C in
, and the calculated fluid generation temperatures (t(Mg-Li)) make it possible to attribute the origin of this nitrogen to the transformation of organic matter during the maturation of sediments.
—
This paper presents the experimental results of rare earth element and yttrium (REY) biosorption in natural surface waters and groundwater in the presence of different concentrations of living and ...inactivated organotrophic bacteria (
Curtobacterium
sp.,
Ralstonia
sp.,
Pseudomonas
sp.,
Bacillus
sp.,
Brevibacterium
sp.,
Microbacterium
sp.,) under different environmental pH conditions. We found that the biosorption process is mainly regulated by two factors: the pH of the aqueous solution and the species of bacteria. The acidity significantly affected the sorption capacity of bacteria for all of the studied strains. We found a decrease in REY sorption with an increase in pH due to lower absorption of REY on the cell walls of bacteria. The process of REY biosorption was more intensive in the living bacteria than inactivated microorganisms. At neutral pH values, all studied bacterial strains more actively adsorbed light REYs (lanthanum, praseodymium, and neodymium), in more acidic solutions (pH 2), an increase in
K
d
values for heavy REY (lutetium and europium) was observed. The effect of bacterial biomass concentration on REY biosorption was demonstrated. The REY sorption decreased with an increase in the concentration of the live and inactivated bacteria.
This paper reports the results of the experimental determination of the coefficient of sorption of rare-earth elements and yttrium (REY) under conditions of acidic pH using several strains of ...heterotrophic bacteria (
Microbacterium
sp.,
Curtobacterium
sp.,
Bacillus subtilis
,
Pseudomonas putida
, and
Bacillus pumilis
) that are widespread in natural and technogenic waters of the Far East (Russia). Insignificant fractionation between heavy and light rare-earth elements, negative cerium and dysprosium anomalies, and a positive europium anomaly were revealed. The selectivity of REY biosorption by gram-positive and gram-negative bacteria, as well as inertia of the biosorption process under more acidic conditions of the medium, were shown.
Computations of screening masses in finite-temperature QCD at finite density are plagued by the sign problem and have been performed so far with an imaginary chemical potential. Here, we use a dual ...formulation of a Polyakov-loop model which allows the determination of screening masses at real baryon chemical potential. This is a second paper in a series devoted to a detailed study of dual Polyakov-loop models at finite density. While the first paper was mainly devoted to establishing the phase diagram of the model, here we compute correlation functions of the Polyakov loops and the second-moment correlation length at non-zero chemical potential. This enables us to evaluate numerically the screening masses from correlations of the real and imaginary parts of the Polyakov loops. We also compute these masses in the mean-field approximation and compare with numerical results. In addition, we provide a quantitative improvement of the general phase diagram presented in the first paper.
Three-quark potentials are studied in great details in the three-dimensional SU(3) pure gauge theory at finite temperature, for the cases of static sources in the fundamental and adjoint ...representations. For this purpose, the corresponding Polyakov loop model in its simplest version is adopted. The potentials in question, as well as the conventional quark–anti-quark potentials, are calculated numerically both in the confinement and deconfinement phases. Results are compared to available analytical predictions at strong coupling and in the limit of large number of colours N. The three-quark potential is tested against the expected Δ and Y laws and the 3q string tension entering these laws is compared to the conventional qq¯ string tension. As a byproduct of this investigation, essential features of the critical behaviour across the deconfinement transition are elucidated.
Many Polyakov loop models can be written in a dual formulation which is free of sign problem even when a non-vanishing baryon chemical potential is introduced in the action. Here, results of ...numerical simulations of a dual representation of one such effective Polyakov loop model at finite baryon density are presented. We compute various local observables such as energy density, baryon density, quark condensate and describe in details the phase diagram of the model. The regions of the first order phase transition and the crossover, as well as the line of the second order phase transition, are established. We also compute several correlation functions of the Polyakov loops.
Geological and hydrogeological characteristics of the Lozovy ridge (Southern Primorye) are studied, as far as karst phenomena are widely distributed within its boundaries. Water-bearing rocks of the ...karst water source "Silver Spring" ("Serebryany Klyuch"), which is located near the bottom of the "Bear's fang" ("Medvezhiy klyk") cave, are investigated. It is found that karst rocks are presented by calcite (CaCO3), and an accessory mineral is barite (BaSO4). It is determined that among the trace elements forming the composition of carbonate water-bearing rocks the maximum concentrations are typical for Sr, Ba, Fe, Al, Za, Mn, Cu, and Ni. Also, the chemical composition of the waters taken from the "Silver Spring" water source is studied. These waters are fresh, hydrocarbonate, calcium, and weakly alkaline. Among the elements of the spring, such elements as Sr, Ba, Fe, Al, Zn, Mn, Cu, and Ni have the maximum concentration. The other elements have concentrations less than 1 µg/l.
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