Stress evolution in plastically deformed austenitic and ferritic steels determined using angle- and energy-dispersive diffraction

In the presented research, the intergranular elastic interaction and the second-order plastic incompatibility stress in textured ferritic and austenitic steels were investigated by means of diffraction. The lattice strains were measured inside the samples by the multiple reflection method using high energy X-rays diffraction during uniaxial in situ tensile tests. Comparing experiment with various models of intergranular interaction, it was found that the Eshelby-Kr\"oner model correctly approximates the X-ray stress factors (XSFs) for different reflections hkl and scattering vector orientations. The verified XSFs were used to investigate the evolution of the first and second-order stresses in both austenitic and ferritic steels. It was shown that considering only the elastic anisotropy, the non-linearity of $\sin^2{\psi}$ plots cannot be explained by crystallographic texture. Therefore, a more advanced method based on elastic-plastic self-consistent modeling (EPSC) is required for the analysis. Using such methodology the non-linearities of $\cos^2{\phi}$ plots were explained, and the evolutions of the first and second-order stresses were determined. It was found that plastic deformation of about 1- 2% can completely exchange the state of second-order plastic incompatibility stresses

Stress evolution in plastically deformed austenitic and ferritic steels determined using angle- and energy-dispersive diffraction

In the presented research, the intergranular elastic interaction and the second-order plastic incompatibility stress in textured ferritic and austenitic steels were investigated by means of diffraction. The lattice strains were measured inside the samples by the multiple reflection method using high energy X-rays diffraction during uniaxial in situ tensile tests. Comparing experiment with various models of intergranular interaction, it was found that the Eshelby-Kr¨oner model correctly approximates the X-ray stress factors (XSFs) for different reflections hkl and scattering vector orientations. The verified XSFs were used to investigate the evolution of the first and second-order stresses in both austenitic and ferritic steels. It was shown that considering only the elastic anisotropy, the non-linearity of sin2ψ plots cannot be explained by crystallographic texture. Therefore, a more advanced method based on elastic-plastic self-consistent modeling (EPSC) is required for the analysis. Using such methodology the non-linearities of cos2φ plots were explained, and the evolutions of the first and second-order stresses were determined. It was found that plastic deformation of about 1–2% can completely exchange the state of second-order plastic incompatibility stresses

Inhibitors of trypanosoma cruzi Sir2 related protein 1 as potential drugs against Chagas disease.

Chagas disease remains one of the most neglected diseases in the world despite being the most important parasitic disease in Latin America. The characteristic chronic manifestation of chagasic cardiomyopathy is the region's leading cause of heart-related illness, causing significant mortality and morbidity. Due to the limited available therapeutic options, new drugs are urgently needed to control the disease. Sirtuins, also called Silent information regulator 2 (Sir2) proteins have long been suggested as interesting targets to treat different diseases, including parasitic infections. Recent studies on Trypanosoma cruzi sirtuins have hinted at the possibility to exploit these enzymes as a possible drug targets. In the present work, the T. cruzi Sir2 related protein 1 (TcSir2rp1) is genetically validated as a drug target and biochemically characterized for its NAD+-dependent deacetylase activity and its inhibition by the classic sirtuin inhibitor nicotinamide, as well as by bisnaphthalimidopropyl (BNIP) derivatives, a class of parasite sirtuin inhibitors. BNIPs ability to inhibit TcSir2rp1, and anti-parasitic activity against T. cruzi amastigotes in vitro were investigated. The compound BNIP Spermidine (BNIPSpd) (9), was found to be the most potent inhibitor of TcSir2rp1. Moreover, this compound showed altered trypanocidal activity against TcSir2rp1 overexpressing epimastigotes and anti-parasitic activity similar to the reference drug benznidazole against the medically important amastigotes, while having the highest selectivity index amongst the compounds tested. Unfortunately, BNIPSpd failed to treat a mouse model of Chagas disease, possibly due to its pharmacokinetic profile. Medicinal chemistry modifications of the compound, as well as alternative formulations may improve activity and pharmacokinetics in the future. Additionally, an initial TcSIR2rp1 model in complex with p53 peptide substrate was obtained from low resolution X-ray data (3.5 Å) to gain insight into the potential specificity of the interaction with the BNIP compounds. In conclusion, the search for TcSir2rp1 specific inhibitors may represent a valuable strategy for drug discovery against T. cruzi

Dysfunctional coping with stress in psychosis. An investigation with the Maladaptive and Adaptive Coping Styles (MAX) questionnaire

Objective: Psychotic episodes have long been conceptualized as inevitable incidents triggered by endogenous biological impairments. It is now well-accepted that the ability of an individual to deal with social and environmental challenges plays an important role in regard to whether or not a vulnerability to psychosis translates into symptoms. For the present study, we examined symptomatic correlates of dysfunctional coping in psychosis and aimed to elucidate a profile of coping strategies that distinguishes patients with schizophrenia from those with depression. Method: The newly devised Maladaptive and Adaptive Coping Styles Scale (MAX) was administered to 75 individuals with psychosis, 100 individuals with depression and 1100 nonclinical controls. Results: Schizophrenia patients showed compromised coping abilities relative to nonclinical controls, particularly a lack of engaging in adaptive coping. Depression was more closely tied to dysfunctional coping than were positive symptoms as indicated by group comparisons and correlational analyses. Correlations between positive symptoms, particularly paranoid symptoms, and avoidance and suppression remained significant when depression was controlled for. Conclusions: Although maladaptive and adaptive coping are unlikely to represent proximal mechanisms for the pathogenesis of positive symptoms, fostering coping skills may reduce positive symptoms via the improvement of depressive symptoms, which are increasingly regarded as risk factors for core psychotic symptoms. Furthermore, the reduction of avoidance and suppression may directly improve positive symptoms

Measurements and Modelling of Nitrogen Species in CH4/O2/N2 Flames Doped with NO, NH3, or NH3+NO

International audienc

A novel approach for nondestructive depth resolved analysis of residual stress and grain interaction in the near surface zone applied to an austenitic stainless steel sample subjected to mechanical polishing

The choice of the grain interaction model is a critical element of residual stress analysis using diffraction methods. For the near surface region of a mechanically polished austenitic steel, it is shown that the application of the widely used Eshelby Kröner model does not lead to a satisfactory agreement with experimental observations. Therefore, a new grain interaction model called tunable free surface is proposed, allowing for the determination of the in depth evolution of the elastic interaction between grains. It has a strong physical justification and is adjusted to experimental data using three complementary verification methods. It is shown that a significant relaxation of the intergranular stresses perpendicular to the sample surface occurs in the subsurface layer having a thickness comparable with the average size of the grain. Using the new type of X ray Stress Factors, the in depth evolution up to the depth of 45 amp; 956;m of residual stresses and of the strain free lattice parameter is determine

Time resolved optical detection for white matter lesion detection: preclinical tests on macaque brains and MRI co-registration

International audienceWe conducted a preclinical assessment on young macaques aimed at detecting white matter lesions. We present the protocol we implemented to achieve the lesions detection using a bedside non-invasive optical-based Time-Resolved instrumentation we have optimized for this purpose. We validated the reconstructed 3D absorption map with co-registration of MRI data. © (2015) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only