The effect of the preliminary deformation and heat treatment by all-round forging under conditions of short-term high-temperature creep on the microstructure and mechanical properties of a composite ...material based on a high-strength aluminum alloy of the Al–Cu–Mg–Zn system (Al7075) strengthened with SiC particles (10 wt %) is investigated. The most effective regime of short-term high-temperature creep is established experimentally. It is found that an avalanche-like increase in the rate of relative deformation occurs upon heating to temperatures above 500°C. This increase is due to the local appearance of a liquid phase at the boundaries between the needle-like particles of the
S
-phase and an Al based solid solution in the composite matrix in accordance with the eutectic transformation α-Al +
S
(Al
2
CuMg) →
L
. After deformation and heat treatment, reinforcing SiC particles are redistributed and the structure of the composite is transformed from a cellular to a uniform configuration. At the same time, the micromechanical properties are leveled over the volume of the composite. The maximum value of the resistance to deformation in the axial compression test increases.
The microstructural transformation of an aluminum matrix composite (AMC) under the conditions of short-term high-temperature creep at temperatures in the range 470–570°C has been studied. The ...possibility of its nondestructive deformation predominantly under compressive stresses at pressures below the creep limit has been established. It has been shown that structural transformations in the aluminum matrix (Al–6Zn–2.5Mg–2Cu alloy) are promotive for essential deformability of this material. At temperatures above 530°C, an increase in the deformation rate and true strain value is caused by the local formation of a liquid phase by the eutectic reaction α +
S
(Al
2
CuMg) →
L
. Under compressive stresses at a deformation temperature of 540–570°C, the formed alloy flows into the micropores between SiC filler particles. In this case, silicon carbide partially dissolves in the aluminum matrix to strengthen the bonds between the matrix and the filler.
The corrosion resistance of SAF 2507 duplex stainless steel and 254 SMO superaustenitic steel is studied in aggressive sulfuric-acid solutions (mother liquor) from sulfate departments; in aggressive ...media from arsenic–soda desulfurization; and in coke-shop media (from the quenching car and quenching tower). Gravimetric tests are conducted in accordance with State Standard GOST 9.908–85. The research is conducted both at coke plants and in the laboratory. It follows from gravimetric tests and cyclic volt–ampere measurements that these materials are highly resistant to point and pitting corrosion in the aggressive media considered. Such corrosion processes are provoked by the presence of activators (H
2
S, HCN, HCNS, and Cl
–
). These findings are confirmed by the considerable life of passive films of molybdenum-bearing steel. Research shows that SAF 2507 (
#Kh25H7AM4#
) duplex steel and Avesta 254S MO superaustenitic steel are highly resistant to point and slot corrosion and outperform the ordinary
#0Kh23N28M3D3T, 10Kh17N13M2T,#
and
#12Kh18M10T#
steels used for heat-exchanger production.
Data obtained by modeling the responses of cardiomyocytes in a state of simulated fi brillation to bipolar depolarizing half-sinusoidal defibrillation pulses with different second-phase relative ...amplitudes were used to construct plots of the relationship between the proportion of the fi brillation cycle in which the defibrillation pulse caused long-lasting lengthening of the cardiomyocyte refractory period (the defibrillation completeness index) and defibrillation pulse energy. These plots showed that bipolar defibrillation pulses provide greater defibrillation completeness indices at lower energy than monopolar pulses.
Abstract
The iThemba Laboratory for Accelerator Based Sciences (iThemba LABS) is a centre of expertise and innovation in the field of nuclear-structure physics and is a leader in several high-impact ...studies. One of the highlights of these nuclear-structure experiments is the study of the broad structure of the IsoVector Giant Dipole Resonance (IVGDR) in the rare-earth region. Proton inelastic scattering experiments with
E
p
= 200 MeV were performed on the even-even Nd isotope chain and
152
Sm at very forward scattering angles including zero degrees with the K600 magnetic spectrometer. The evolution of the shape of the IVGDR in the transition from spherical to deformed nuclei was investigated. One of the goals of this highlighted study was to confirm the
K
-splitting observed in previous photo-absorption measurements from Saclay. Significant discrepancies were found between the direct (γ, xn) data obtained at Saclay and the equivalent photo-absorption cross sections obtained using (p, p′) data from the K600. Furthermore, discrepancies exist for several nuclei between photo-absorption data taken at the Saclay and Livermore laboratories. These discrepancies, possible reasons for them and future investigations will be presented and discussed.
The T-11M lithium program is focused to find solutions for technological issues of a steady-state tokamak. A recent lithium activity in T-11M was focused on three directions: investigation of ...different Li-limiters, investigations of long-term effects of lithium behavior in hydrogen plasmas and development of a new kind of CPS limiters. The new so-called R limiter has been used as Li collector for investigation of lithium fluxes near the plasma boundary and chamber walls. It was shown, that the Li circulation near the limiter exceeds up to four times the primary lithium flux from limiters. 90% of primary flux is collected by lateral sides of limiter and only 10% arrives at the chamber wall. The deuterium glow discharge was used to test the long-term lithium degradation under the deuterium bombardment. It was shown that such degradation is small. That means that the Li-limiter can be used as Li-emitter in steady-state tokamak operation. A new vertical lithium limiter was successfully tested in T-11M.
Introduction. The diagnostic efficacy of methods for hepatitis E serodiagnostic varies over a wide range; therefore, the combined use of tests of various formats is recommended. The aim of the ...research was to develop a test system for the detection of IgG antibodies to hepatitis E virus (HEV) in human serum by linear immunoassay (LIA). Material and methods. Serum samples from patients with hepatitis and healthy individuals were tested using commercial enzyme-linked immunosorbent assay systems for the presence of IgG antibodies to viral agents causing hepatitis and other infections associated with liver pathology. Recombinant antigens ORF2 and ORF3 of HEV genotypes 1 and 3 were used. The “RecomLine HEV IgG/IgM” reagent kit (Mikrogen GmbH, Germany) was used as a comparison test system. Results. The first Russian diagnostic kit “Blot-HEV”, designed to detect IgG antibodies to individual HEV proteins in human serum using LIA, was developed. The antigenic base is represented by strips of a nitrocellulose membrane with immobilized recombinant antigens ORF2 (aa 406–660) and ORF3 (aa 1–113) of HEV genotypes 1 and 3, and control antigens in the form of discrete lines. The conjugate was mouse monoclonal antibodies to human class G immunoglobulins labeled with horseradish peroxidase. The chromogen solution contained the 3,3’,5,5’-tetramethylbenzidine. A visual and digital recording of results was provided. The analytical sensitivity of the test kit was 0.625 IU/ml for ORF2 antigens and 2.5 IU/ml for ORF3 antigens. The absence of the influence of endogenous interfering substances on the results of the analysis and the absence of cross-reactions with antibodies to hepatitis pathogens of the other etiologies had been shown. The sensitivity of the test system compared to the “RecomLine HEV IgG/IgM” kit was 92%, specificity 97%. Shelf life in condition of storage was determined to be 12 months. Conclusions. The developed test can be used to confirm the results of ELISA in laboratory diagnosis of hepatitis E.
The phenomenon of human aging is the result of a complex interaction among several factors in which the immune system plays a key role. Cortisol is a glucocorticoid secreted by the adrenal gland and ...has a specific secretion pattern. The current study aimed at identifying the cause and pathogenesis of premature aging using biological markers. This study was performed based on the results of clinical and instrumental examinations on 91 middle-aged men aged 45-59 years. VaseraVS-1500 sphygmomanometer based on standard methods was used to measure biological age. The relationship between biological age and circadian rhythms of cortisol secretion was calculated to elucidate the pathophysiological mechanisms of aging development. The recorded data showed that the violation of the circadian rhythms of cortisol secretion characterized by a consistently high level of the hormone throughout the day was typical among individuals with accelerated types of aging. Based on the obtained data, a formula for determining the biological age of the studied groups of patients was prepared by considering the circadian rhythm of cortisol secretion, which can be an additional tool for early detection of aging in men.
We report the first experimental determination of independent isomeric yield ratios using direct ion counting with a Penning trap, which offered such a high resolution in mass that isomeric states ...could be separated. The measurements were performed at the Ion Guide Isotope Separator On-Line (IGISOL) facility at the University of Jyvaskyla. The isomer production ratios of Ge-81, Y-96,Y-97 Sn-128(,1)30, and Sb-129 in the 25-MeV proton-induced fission of U-na(t) and Th-232 were studied. Three isomeric pairs (Ge-81, Y-96, and Sb-129) were measured for the first time for the U-na(t)(p, f) reaction, while all the reported yield ratios for the Th-232(p, f) reaction were determined for the first time. The comparison of the experimentally determined isomeric yield ratios with data available in the literature shows a reasonable agreement, except for the case of Sn-130 for unspecified reasons. The obtained results were also compared with the GEF model, where good agreement can be noticed in most cases for both reactions. Serious discrepancies can only be observed for the cases of Y-96(,)97 for both reactions. Moreover, based on the isomeric yield ratios, the root-mean-square angular momenta (J(r)(ms)) of the fission fragments after scission were estimated using the TALYS code. The experimentally determined isomeric yield ratios, and consequently the deduced J(rms), for Sn-130 are significantly lower compared to Sn-128 for both fissioning systems. This can be attributed to the more spherical shape of the fragments that contribute to the formation of Sn-130, due to their proximity to the N = 82 shell closure. The values of J(rms) for Sb-129 are higher than Sn-128 for both reactions, despite the same neutron number of both nuclides (N = 78), indicating the odd-Z effect where fission fragments with odd-Z number tend to bear larger angular momentum than even-Z fragments. The isomer production ratio for the isotopes of Sn is more enhanced in the U-na(t)(p, f) reaction than in Th-232(p, f). The opposite is observed for Y-96 and Y-97. These discrepancies might be associated to different scission shapes of the fragments for the two fission reactions, indicating the impact that the different fission modes can have on the isomeric yield ratios.
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