Wear dynamics of fragments in the lower part of a fuel assembly with unattached rods

The dynamic characteristics and wear of unattached fuel rods in the lower supporting lattice are investigated. The vibrational eigenfrequencies and dynamic rigidity of the fuel rods in different configurations are determined. The vibrational wear at contact between the fuel rods and the spacing elements is studied.     

Seismic isolators for petroleum and gas platforms of the “Sakhalin-2” project

Friction pendulum bearings have universal properties satisfying various demands when supporting buildings, bridges, and industrial facilities. The oscillation period of the bearing, vertical carrying capacity, damping, displacement ability, and ability to receive tensile load can be chosen independently. Dynamic oscillation periods from 1 to 5 s, shifts of up to 1.5 m, high carrying capacity and damping can be provided. Bearings can endure vertical loads of up to 13 500 tons and have minimal construction costs. Data are given on the influence of earthquakes and other force effects on the thermal state and characteristics of frictional pendulum bearings used as seismic isolators on petroleum and gas platforms of the “Sakhalin-2” project.     

Functional interaction of mammalian valyl-tRNA synthetase with elongation factor EF-1alpha in the complex with EF-1H

In mammalian cells valyl-tRNA synthetase (ValRS) forms a high Mr complex with the four subunits of elongation factor EF-1H. The beta, gamma, and delta subunits, that contribute the guanine nucleotide exchange activity of EF-1H, are tightly associated with the NH2-terminal polypeptide extension of valyl-tRNA synthetase. In this study, we have examined the possibility that the functioning of the companion enzyme EF-1alpha could regulate valyl-tRNA synthetase activity. We show here that the addition of EF-1alpha and GTP in excess in the aminoacylation mixture is accompanied by a 2-fold stimulation of valyl-tRNAVal synthesis catalyzed by the valyl-tRNA synthetase component of the ValRS.EF-1H complex. This effect is not observed in the presence of EF-1alpha and GDP or EF-Tu.GTP and requires association of valyl-tRNA synthetase within the ValRS.EF-1H complex. Since valyl-tRNA synthetase and elongation factor EF-1alpha catalyze two consecutive steps of the in vivo tRNA cycle, aminoacylation and formation of the ternary complex EF-1alpha.GTP. Val-tRNAVal that serves as a vector of tRNA from the synthetase to the ribosome, the data suggest a coordinate regulation of these two successive reactions. The EF-1alpha.GTP-dependent stimulation of valyl-tRNA synthetase activity provides further evidence for tRNA channeling during protein synthesis in mammalian cells.     

The nature of the changes in the immunity of the women who worked in the cleanup of the sequelae of the accident at the Chernobyl Atomic Electric Power Station and were evacuated from the radioactively contaminated area

During examination of 37 women taking part in elimination of consequences of Chernobyl's disaster was revealed, that complex of disaster factors action resulted the formation of disbalance in the system of immunocompetence cells and caused the oppression of functional activity of neutrophils. In 110 women living on the radioactive contaminated zone (5-40 Ci/km) the phenomena of the secondary immunodeficiency in the form of defeat as cellular as humoral factors of immunity and nonspecific resistance system was diagnosed.     

The observation of chaperone-ligand noncovalent complexes with electrospray ionization mass spectrometry

Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) was applied for the study of noncovalent chaperone SecB-ligand complexes produced in solution and examined in the gas phase with the aid of electrospray ionization (ESI). Since chaperone proteins are believed to recognize and bind only with ligands with nonnative tertiary structure, this work required careful unfolding of the ligand and subsequent reaction with the intact chaperone (the noncovalent tetrameric protein, SecB). A high denaturant concentration was employed to produce nonnative structures of the OppA, and microdialysis of the resulting solutions containing the chaperone-ligand complexes was carried out to rapidly remove the denaturant prior to analysis. Multistage mass spectrometry was essential to the successful study of these complexes since the initial mass spectra indicated extensive adduction that precluded mass measurements, even after microdialysis. However, low energy collisional activation of the ions in the FTICR trap proved useful for adduct removal, and careful control of excitation level preserved the intact complexes of interest, revealing a 1:1 SecB:OppA stoichiometry. To our knowledge, these results present the first direct observation of chaperone-ligand noncovalent complexes and the highest molecular weight heterogeneous noncovalent complex observed to date by mass spectrometry. Furthermore, these results highlight the capabilities of FTICR for the study of such complex systems, and the development of a greater understanding of chaperone interactions in protein export.     

Wear of the pipe-spacing grating pair of a steam generator in a lead heat carrier

The results of the solution of tribological problems emerging when friction units operate in heavy liquid metals as heat carriers in nuclear power plants are presented. An installation has been developed to simulate the vibrational wear of friction units in heat exchanging tubes of interfaced units with spacing gratings in order to simulate resistance to the vibration of the steam generator of a fast neutron reactor with lead heat carriers. A method of study has been developed, samples of tubes and spacing gratings have been tested for vibrational wear, and metallographic and profilometric exploration has been performed. The wear mechanism is described and the tentative life of the steam generator pipes is assessed.     

Determination of the binding frame of the chaperone SecB within the physiological ligand oligopeptide-binding protein

Chaperone proteins demonstrate the paradoxical ability to bind ligands rapidly and with high affinity but with no apparent sequence specificity. To learn more about this singular property, we have mapped the binding frame of the chaperone SecB from E. coli on the oligopeptide-binding protein. Similar studies performed on the maltose-binding and galactose-binding proteins revealed centrally positioned binding frames of approximately 160 aminoacyl residues. The work described here shows that OppA, which is significantly longer than the previously studied ligands, has a binding frame that covers 460 amino acids, nearly the entire length of the protein. We propose modes of binding to account for the data.     

Fluorescein angiography of retinal changes in patients with neurofibromatosis 2

BACKGROUND: Neurofibromatosis 2 (NF2) is a rare autosomal dominant disorder (prevalence 1:37.000) associated with changes in tumor suppressor genes. Intraocular manifestations have been reported as subcapsular cataract, retinal hamartomas, epiretinal membranes, keratopathy in facial palsy, and tumors of the nerves I-V are typical ocular manifestations of NF2. PATIENTS AND MATERIALS: We prospectively examined 7 patients who met the diagnostic criteria of NF2 with regard to retinal changes using fluorescence angiography and red-free fundus photography. RESULTS: In four patients, we found window defects of the pigment epithelium in the macular or paramacular areas. In one patient we observed a combined pigment epithelial and astrocytic hamartoma. A choked papilla was found in two patients. CONCLUSIONS: Presumably, retinal changes in NF2 occur more frequently than has been assumed previously. Our results confirm that in NF2 patients more attention should be paid to abnormalities of the optic disk, the retina and the choroid.