Вплив електролітично абсорбованого сталлю водню на параметри сигналів магнетоакустичної емісії

This paper presents preliminary results of study on the applicability of magnetoacoustic emission (MAE) method as a tool for sensing the presence of electrolytically absorbed hydrogen in low carbon steel. It is clearly presented that for the employed laboratory settings a MAE signal parameter, which is the sum of amplitudes of MAE signal impulses, is strongly dependent on the presence of hydrogen in the bulk of the material. It is noted that for the low cathodic current there is a delay in time required, probably, for the removal of the corrosion products from the steel surface and providing the conditions for the sufficient amount of hydrogen to be absorbed by the near-the-surface volume of the sample. The results are shortly discussed regarding the issues connected to the applicability of MAE method for nondestructive evaluation (NDE) of hydrogen absorbed by structural materials.Наведено попередні результати досліджень щодо можливості використання методу мегнетоакустичної емісії (МАЕ) для виявлення водню електролітично абсорбованого низьковуглецевою сталлю. Наведені результати переконливо свідчать, що за зазначених умов проведення експерименту параметр сигналу МАЕ, яким є сума амплітуд імпульсів МАЕ, дуже залежить від наявності водню в об’ємі матеріалу. Зазначено, що для низьких катодних струмів спостерігається затримка в часі, необхідна, вірогідно, для відновлення продуктів корозії на поверхні сталі та забезпечення умов для абсорбування достатньої кількості водню приповерхневими шарами металу. Результати коротко обговорені з огляду на перспективність застосування методу МАЕ як засобу неруйнівного контролю водню абсорбованого конструкційними матеріалами

Super fast plasma streams as drivers of transient and anomalous magnetospheric dynamics

Abstract. We present multi spacecraft measurements in the magnetosheath (MSH) and in the solar wind (SW) by Interball, Cluster and Polar, demonstrating that coherent structures with magnetosonic Mach number up to 3 – Supermagnetosonic Plasma Streams (SPS) – generate transient and anomalous boundary dynamics, which may cause substantial displacements of the magnetospheric boundaries and the riddling of peripheral boundary layers. In this regard, for the first time, we describe a direct plasma penetration into the flank boundary layers, which is a candidate for being the dominant transport mechanism for disturbed MSH periods. Typically SPS's have a ram pressure exceeding by several times that of the SW and lead to long-range correlations between processes at the bow shock (BS) and at the magnetopause (MP) on one side and between MSH and MP boundary layers on the other side. We demonstrate that SPS's can be observed both near the BS and near the MP and argue that they are often triggered by hot flow anomalies (HFA), which represent local obstacles to the SW flow and can induce the SPS generation as a means for achieving a local flow balance. Finally, we also discuss other causes of SPS's, both SW-induced and intrinsic to the MSH. SPS's appear to be universal means for establishing a new equilibrium between flowing plasmas and may also prove to be important for astrophysical and fusion applications

Вплив деформації на параметри магнетоакустичних сигналів

This paper presents results on the study of the effect of elastic and plastic deformation of low-carbon steel on magnetoacoustic emission (MAE) performed with the measuring system MAE-1L. Generally, the observed tendencies of reduction of MAE with deformation of iron-based alloys confirm those published in the literature. The reproducibility of measurements in the ealstic region is very high. As to the plastic region it demands further investigations. These measurements confirmed the perspectiveness of the method MAE for nondestructive evaluation (NDE) of plastically damaged parts of operated equipment or structures. MAE-1L system exhibited an appropriate service performance.Наведено результати досліджень впливу пружної та пластичної деформацій низьковуглецевої сталі на мегнетоакустичну емісію (МАЕ) із використанням вимірювальної системи MAE-1L. Виявлені тенденції зниження МАЕ із деформуванням сплавів на основі заліза загалом збігаються із опублікованими даними. Відтворюваність вимірювань на ділянці пружних деформацій є дуже висока. Щодо пластичної ділянки, необхідні подальші дослідження. Наведені результати підтверджують перспективність методу МАЕ для неруйнівного контролю ділянок діючого обладнання та споруд, які зазнали пластичного деформування. Система МАЕ-1L продемонструвала належну працездатність

Experimental study of nonlinear interaction of plasma flow with charged thin current sheets: 1. Boundary structure and motion

We study plasma transport at a thin magnetopause (MP), described hereafter as a thin current sheet (TCS), observed by Cluster at the southern cusp on 13 February 2001 around 20:01 UT. The Cluster observations generally agree with the predictions of the Gas Dynamic Convection Field (GDCF) model in the magnetosheath (MSH) up to the MSH boundary layer, where significant differences are seen. We find for the MP a normal roughly along the GSE x-axis, which implies a clear departure from the local average MP normal, a ~90 km thickness and an outward speed of 35 km/s. Two populations are identified in the MSH boundary layer: the first one roughly perpendicular to the MSH magnetic field, which we interpret as the &quot;incident&quot; MSH plasma, the second one mostly parallel to <b>B</b>. Just after the MP crossing a velocity jet is observed with a peak speed of 240 km/s, perpendicular to <b>B</b>, with <i>M_A</i>=3 and &beta;>10 (peak value 23). The magnetic field clock angle rotates by 70&deg; across the MP. <i>E_x</i> is the main electric field component on both sides of the MP, displaying a bipolar signature, positive on the MSH side and negative on the opposite side, corresponding to a ~300 V electric potential jump across the TCS. The <i>E</i>&times;<i>B</i> velocity generally coincides with the perpendicular velocity measured by CIS; however, in the speed jet a difference between the two is observed, which suggests the need for an extra flow source. We propose that the MP TCS can act locally as an obstacle for low-energy ions (&lt;350 eV), being transparent for ions with larger gyroradius. As a result, the penetration of plasma by finite gyroradius is considered as a possible source for the jet. The role of reconnection is briefly discussed. The electrodynamics of the TCS along with mass and momentum transfer across it are further discussed in the companion paper by Savin et al. (2006)

MIR376A is a regulator of starvation-induced autophagy

Background: Autophagy is a vesicular trafficking process responsible for the degradation of long-lived, misfolded or abnormal proteins, as well as damaged or surplus organelles. Abnormalities of the autophagic activity may result in the accumulation of protein aggregates, organelle dysfunction, and autophagy disorders were associated with various diseases. Hence, mechanisms of autophagy regulation are under exploration. Methods: Over-expression of hsa-miR-376a1 (shortly MIR376A) was performed to evaluate its effects on autophagy. Autophagy-related targets of the miRNA were predicted using Microcosm Targets and MIRanda bioinformatics tools and experimentally validated. Endogenous miRNA was blocked using antagomirs and the effects on target expression and autophagy were analyzed. Luciferase tests were performed to confirm that 3’ UTR sequences in target genes were functional. Differential expression of MIR376A and the related MIR376B was compared using TaqMan quantitative PCR. Results: Here, we demonstrated that, a microRNA (miRNA) from the DlkI/Gtl2 gene cluster, MIR376A, played an important role in autophagy regulation. We showed that, amino acid and serum starvation-induced autophagy was blocked by MIR376A overexpression in MCF-7 and Huh-7 cells. MIR376A shared the same seed sequence and had overlapping targets with MIR376B, and similarly blocked the expression of key autophagy proteins ATG4C and BECN1 (Beclin 1). Indeed, 3’ UTR sequences in the mRNA of these autophagy proteins were responsive to MIR376A in luciferase assays. Antagomir tests showed that, endogenous MIR376A was participating to the control of ATG4C and BECN1 transcript and protein levels. Moreover, blockage of endogenous MIR376A accelerated starvation-induced autophagic activity. Interestingly, MIR376A and MIR376B levels were increased with different kinetics in response to starvation stress and tissue-specific level differences were also observed, pointing out to an overlapping but miRNA-specific biological role. Conclusions: Our findings underline the importance of miRNAs encoded by the DlkI/Gtl2 gene cluster in stress-response control mechanisms, and introduce MIR376A as a new regulator of autophagy

Small RNA analysis in Sindbis virus infected human HEK293 cells

In contrast to the defence mechanism of RNA interference (RNAi) in plants and invertebrates, its role in the innate response to virus infection of mammals is a matter of debate. Since RNAi has a well-established role in controlling infection of the alphavirus Sindbis virus (SINV) in insects, we have used this virus to investigate the role of RNAi in SINV infection of human cells