The electrochemical properties of a series of sterically hindered
o
-benzoquinones in aprotic solvents were examined. The reaction of O
2
and KO
2
with
o
-benzoquinones and electrogenerated
o
...-semiquinone radical anions was studied. The formation of
o
-semiquinone radical anions in the reactions of KO
2
with the studied
o
-quinones was detected using UV-visible and ESR spectroscopy. The influence of the test compounds on lipid peroxidation was considered at the molecular and tissue levels
in vitro
. In the most cases,
o
-quinones exhibit antioxidant activity, which varies depending on the type of lipid substrate.
New sterically hindered catecholaldimines derived from hydrazine were synthesized in high yields. Two procedures for the synthesis of sterically hindered catecholaldimines were developed: by the ...reaction of 4,6-di-
tert
-butyl-2,3-dihydroxybenzaldehyde with hydrazines (hydrazine hydrate, phenyl-, 1,1-diphenyl-, and (diphenylmethylene)hydrazines, acetyl and benzoyl hydrazides) or by the reaction of 3,5-di-
tert
-butyl-6-(hydrazonomethyl)catechol with a carbonyl compound (the reaction with 4-
N,N
-dimethylaminobenzaldehyde). The X-ray diffraction analysis and IR, UV, and NMR spectroscopic studies showed that these compounds exist in the catecholic form both in solution and the crystalline state.
A one-step procedure was developed for the multigram synthesis of 5,5,8,8-tetramethyl-5,6,7,8-tetrahydronaphthalene-2,3-diol, and its three 1-substituted derivatives and 1-substituted ...5,5,8,8-tetramethyl-5,6,7,8-tetrahydronaphthalene-2,3-dione were obtained.
The kinetics of photoreduction under the action of visible light of the 3,6-di-
tert
-butyl-
o
-benzoquinone moiety in methacrylic monomer, polymer, and in the graft layer on the surface of pores in ...the presence of different
N
,
N
-dimethylanilines has been studied. The reaction is accelerated with the increasing electron-donating ability of the amine. In the presence of
N
,
N
-dimethylaniline at 50-fold molar excess of the amine, the photoreduction in the porous polymer occurs three and four times faster than in the monomer and the polymer, respectively.
A one-step procedure was developed for the multigram synthesis of 5,5,8,8-tetramethyl-5,6,7,8-tetrahydronaphthalene-2,3-diol, and its three 1-substituted derivatives and 1-substituted ...5,5,8,8-tetramethyl-5,6,7,8-tetrahydronaphthalene-2,3-dione were obtained.
We show that the completely bound classical motion of a positive-energy electron is realized in the Coulomb field of a motionless nucleus and a uniform magnetic field. Such a motion exists due to ...conservation of the so-called invariant tori in the phase space of the system for not only the negative, but also for the positive energy of an electron. The completely bound trajectories occupy a much larger interval of the velocity directions compared with free trajectories for the same energy in a range of distances from the nucleus in which the typical time of the electron transit near the nucleus is larger than the cyclotron-gyration period, while the negative energy of Coulomb interaction is larger (in absolute value) than the total electron energy. The indicated range of distances is realized in the case of a low electron energy or a strong magnetic field when the Larmor radius of the electron is smaller than the characteristic impact parameter of the close Coulomb collisions in the absence of a magnetic field. The required conditions are realized in the photospheres of isolated magnetic white dwarfs and in the experiments on creation of antihydrogen.
Growth hormone somatotropin and its membrane receptor GHR, belonging to a superfamily of the type I receptors possessing tyrosine kinase activity, are involved in the intercellular signal ...transduction cascade and regulate a number of important physiological and pathological processes in humans. Binding with somatotropin triggers a transition of GHR between two alternative dimer states, resulting in an allosteric activation of JAK2 tyrosine kinase in the cell cytoplasm. Transmembrane domain of GHR directly involved in this complex conformational transition. It has presumably two dimerization interfaces corresponding to the "unliganded" and the active state of GHR. In order to study the molecular basis of biochemical signal transduction mechanism across the cell membrane, we have developed an efficient cell-free production system of a TM fragment of GHR, which contains its TM domain flanked by functionally important juxtamembrane regions (GHRtm residues 254-298). The developed system allows to obtain -1 mg per 1 ml of reaction mixture of 13C- and 15N-isotope-labeled protein for structural and dynamic studies of the GHR TM domain dimerization in the membrane-mimicking medium by high-resolution heteronuclear NMR spectroscopy.
Background. Nowadays dissolution of uric acid kidney stones is the first line treatment according to existing clinical guidelines. Besides dual-energy CT, which is costly, there is no non-invasive ...tool to predict uric acid stone composition.Aim. To develop a new tool for uric acid stones prediction which will improve patient selection for oral stone dissolution therapy.Materials and methods. We retrospectively analyzed treatment results of 189 patients which were distributed to two groups: with pure uric acid stones - 59 patients and with other composition - 130 patients. Demographic data, results of 24 hour urine analysis and CT scans were analyzed.Results. Among above mentioned parameters the following had the highest significance: body mass, body mass index, urine pH and stone density in Hounsfield Units (p<0.01). Product of multiplication of urine pH and CT-stone density called «Urate index» yielded highest AUC (0.96) which permitted with high accuracy diagnose uric acid stones.Conclusion. «Urate-index» is simple to obtain and has high predictive value which might help choosing target population for kidney stone dissolution.
A reaction of 4,6-di-
tert
-butyl-2,3-dihydroxybenzaldehyde with aliphatic (ethylenediamine, propylene-1,3-diamine, 1,4-diaminobutane) and aromatic (
o
-,
m-
,
p
-phenylenediamines, ...1,8-diaminonaphthalene, benzidine) diamines leads to the Schiff bases containing fragments of sterically hindered catechols in high yields (up to 97%). The products exist in two tautomeric forms in solutions and in the crystalline state. In the case of aliphatic diamines, catecholaldimines exist in solutions in the quinomethide form, whereas in the case of aromatic, in the catechol form. In the crystalline state, the position of the hydrogen atom in the O-H…N fragment is also affected by the intermolecular hydrogen bonds, which promote stabilization of the quinomethide form of catecholaldimines.
In the frame of the FCC study we are designing a 27 TeV hadron collider in the LHC tunnel, called the High Energy LHC (HE-LHC). The HE-LHC can be realized by replacing the LHC's 8.33 T ...niobium-titanium dipole magnets with 16 T niobium-tin magnets developed for FCC-hh. A high-quality beam available from the upgraded LHC injector complex and significant radiation damping allow achieving the challenging target values for both peak and integrated luminosity required by particle physics. Tunnel integration determines the maximum outer size of the magnet cryAPCostat. The HE-LHC arc optics maximizes the dipole filling factor and optimizes the dynamic aperture, while limiting the field strengths of quadrupoles and sextupoles. The low-beta optics for the experimental insertions features a shielded quadrupole triplet even longer than the HL-LHC's, which can support an interaction-point beta function of 25 cm, and survive an integrated luminosity above 10/ab. Other challenges include collimation and extraction. The choice of injection energy and injector is another important element, and so are various collective effects. We here report the HE-LHC design status.
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