Effect of multiple forging and annealing on microstructure and mechanical properties of a high-manganese steel

The effect of multiple forging and annealing on the microstructure and mechanical properties of a high-manganese steel is considered. An austenitic high-manganese steel, Fe-0.03C-28Mn-1.5Al (all in wt.%), with an average grain size of about 37 qm was used as th initial material in this study. Multiple forging at room temperature was carried out up to a total true strain of 2. Multiple forging was accompanied by deformation twinning and resulted in significant strengthening. The steel samples subjected to multiple forging demonstrate an increase in the strength properties with an increase in the total strain, while elongation decrease

Optimally shaped terahertz pulses for phase retrieval in a Rydberg atom data register

We employ Optimal Control Theory to discover an efficient information retrieval algorithm that can be performed on a Rydberg atom data register using a shaped terahertz pulse. The register is a Rydberg wave packet with one consituent orbital phase-reversed from the others (the ``marked bit''). The terahertz pulse that performs the decoding algorithm does so by by driving electron probability density into the marked orbital. Its shape is calculated by modifying the target of an optimal control problem so that it represents the direct product of all correct solutions to the algorithm.Comment: 6 pages, 3 figure

Observation of narrow baryon resonance decaying into pKs0pK^0_s in pA-interactions at 70GeV/c70 GeV/c with SVD-2 setup

SVD-2 experiment data have been analyzed to search for an exotic baryon state, the $\Theta^+$-baryon, in a $pK^0_s$ decay mode at $70 GeV/c$ on IHEP accelerator. The reaction $pA \to pK^0_s+X$ with a limited multiplicity was used in the analysis. The $pK^0_s$ invariant mass spectrum shows a resonant structure with $M=1526\pm3(stat.)\pm 3(syst.) MeV/c^2$ and $\Gamma < 24 MeV/c^2$. The statistical significance of this peak was estimated to be of $5.6 \sigma$. The mass and width of the resonance is compatible with the recently reported $\Theta^+$- baryon with positive strangeness which was predicted as an exotic pentaquark ($uudd\bar{s}$) baryon state. The total cross section for $\Theta^+$ production in pN-interactions for $X_F\ge 0$ was estimated to be $(30\div120) \mu b$ and no essential deviation from A-dependence for inelastic events $(\sim A^{0.7})$ was found.Comment: 8 pages, 7 figures, To be submitted to Yadernaya Fizika. v3-v5 - Some references added, minor typos correcte

Properties of Neutral Charmed Mesons in Proton--Nucleus Interactions at 70 GeV

The results of treatment of data obtained in the SERP-E-184experiment "Investigation of mechanisms of the production of charmed particles in proton-nucleus interactions at 70 GeV and their decays" by irradiating the active target of the SVD-2 facility consisting of carbon, silicon, and lead plates, are presented. After separating a signal from the two-particle decay of neutral charmed mesons and estimating the cross section for charm production at a threshold energy {\sigma}(c\v{c})=7.1 \pm 2.4(stat.) \pm 1.4(syst.) \mub/nucleon, some properties of D mesons are investigated. These include the dependence of the cross section on the target mass number (its A dependence); the behavior of the differential cross sections d{\sigma}/dpt2 and d{\sigma}/dxF; and the dependence of the parameter {\alpha} on the kinematical variables xF, pt2, and plab. The experimental results in question are compared with predictions obtained on the basis of the FRITIOF7.02 code.Comment: 9 pages, 9 figures,3 table

In-situ temperatures and thermal properties of the East Siberian Arctic shelf sediments: Key input for understanding the dynamics of subsea permafrost

Significant reserves of methane (CH4) are held in the Arctic shelf, but the release of CH4 to the overlying ocean and, subsequently, to the atmosphere has been believed to be restricted by impermeable subsea permafrost, which has sealed the upper sediment layers for thousands of years. Our studies demonstrate progressive degradation of subsea permafrost which controls the scales of CH4 release from the sediment into the water-atmospheric system. Thus, new knowledge about the thermal state of subsea permafrost is crucial for better understanding of the permafrost -hydrate system and associated CH4 release from the East Siberian Arctic Shelf (ESAS) – the broadest and shallowest shelf in the World Ocean, which contains about 80% of subsea permafrost and giant pools of hydrates. Meanwhile, the ESAS, still presents large knowledge gaps in many aspects, especially with respect to subsea permafrost distribution and physical properties of bottom sediments. New field data show that the ESAS has an unfrozen (ice-free) upper sediment layer, which in-situ temperature is −1.0 to −1.8 °C and 0.6оС above the freezing point. On one hand, these cold temperature patterns may be related to the presence of subsea permafrost, which currently primarily occurs in the part of the ESAS that is shallower than 100 m, while ice-bearing sediments may also exist locally under deeper water in the Laptev Sea. On the other hand, the negative bottom sediment temperatures of −1.8 °C measured on the Laptev Sea continental slope sediments underlying water columns as deep as down to 330 m may result from dissociation of gas hydrates or possibly from dense water cascading down from the shelf. In contrast, data collected on recent expeditions in the northern Laptev shelf, zones of warmer bottom temperatures are coinciding with methane seeps, likely induced by seismic and tectonic activity in the area. These warm temperatures are not seen in the East Siberian Sea area, not even in areas of methane seeps, yet with little seismic activity. The thermal conductivity and heat capacity of bottom sediments recorded in the database of thermal parameters for the ESAS areas mainly depend on their lithification degree (density or porosity), moisture content, and particle size distribution. The thermal conductivity and heat capacity average about 1.0 W/(m·K) and 2900 kJ/(m3·K), with ±20% and ±10% variance, respectively, in all sampled Arctic sediments to a sub-bottom interval of 0–0.5 m

Comparative morphological characteristics of the uteroplacental area in abnormal placentation

The aim. To carry out a comparative morphological characteristic of the uteroplacental area with abnormal placentation – pl. accreta, pl. increta, pl. percreta. Materials and methods. The study included 47 patients with atypical placentation; the comparison group included 10 healthy pregnant women with uterine scar after a previous caesarean section. A histological study of uteroplacental area samples was performed with hematoxylin and eosin, methylene blue staining. An immunohistochemical study with primary antibodies to cytokeratin 7 (CK7), Hif2a, vascular endothelial growth factor, α-SMA was carried out. The differences between the compared values were considered to be statistically significant at p &lt; 0.05. The results of the study. Pl. accreta was determined in 12 (25.5 %), pl. increta – in 30 (63.9 %), pl. percreta – in 5 (10.6 %) patients. In all patients of the main group, the decidua was completely or partially absent in the area of abnormal placentation or was replaced by an uneven layer of fetal fibrinoid. Cases when placental villi unevenly penetrated into the thickness of myometrium in the form of “tongues” or “coves” bordered by fetal fibrinoid and often located intermuscularly were defined as pl. increta (n = 26). Cases with the placental villi ingrowth to the serous membrane were considered as pl.  percreta (n  =  5). In cases with deep variants of  ingrowth (pl. increta and pl. percreta) (n = 31), the villi were visualized in the lumen of the vessels and the thinning of the lower uterine segment with the presence of stretched muscle bundles was revealed. Aseptic necrosis of  the myometrium was  found: in 2 (16.7 %) of 12 women with pl. accreta, in 26 (86.7 %) of 30 women with pl. increta and in 5 (100 %) women with pl. percreta. There were no areas of necrosis in the myometrium of the women of comparison group. Conclusion. The appearance and increase of myometrial necrosis zones in response to an increase in the depth of placental villus ingrowth were detected. Myometrial necrosis zones could be the cause of activation of angiogenic factors and an important stimulus for the development of abnormal vascularization in placenta accreta spectrum