Digestive alkaline proteases from the Tunisian barbel (Barbus callensis): Characterization and application as a detergent additive, in chicken feather-degradation and as a dehairing agent

Alkaline crude enzymes from the viscera of the Tunisian barbel (Barbus callensis) were extracted and characterized. Proteolytic crude extract from barbel viscera was active and stable in alkaline solution. The optimum pH and temperature were 11.0 and 55 °C, respectively, using casein as a substrate. The crude alkaline protease was extremely stable in the pH range of 5.0-12.0. Zymography activity staining using casein as a substrate showed the presence of at least five distinct proteases. The crude alkaline proteases showed stability towards various surfactants, bleach agents and compatibility with some commercial detergents. Alkaline proteases from the viscera of the barbel were tested in chicken feather-degradation and showed important feather degrading activity. Complete solubilisation of whole feathers was observed after 24h of incubation at 50°C. Additionally, crude alkaline protease demonstrated powerful capabilities of hair removal from skin and the collagen, the major leather-forming protein, was not significantly degraded. Considering its promising properties, alkaline crude enzyme from the viscera of the Tunisian barbel may be considered as a potential candidate for future use in several biotechnological processes

Feasibility of Using Ultra-High Field (7 T) MRI for Clinical Surgical Targeting

The advantages of ultra-high magnetic field (7 Tesla) MRI for basic science research and neuroscience applications have proven invaluable. Structural and functional MR images of the human brain acquired at 7 T exhibit rich information content with potential utility for clinical applications. However, (1) substantial increases in susceptibility artifacts, and (2) geometrical distortions at 7 T would be detrimental for stereotactic surgeries such as deep brain stimulation (DBS), which typically use 1.5 T images for surgical planning. Here, we explore whether these issues can be addressed, making feasible the use of 7 T MRI to guide surgical planning. Twelve patients with Parkinson's disease, candidates for DBS, were scanned on a standard clinical 1.5 T MRI and a 7 T MRI scanner. Qualitative and quantitative assessments of global and regional distortion were evaluated based on anatomical landmarks and transformation matrix values. Our analyses show that distances between identical landmarks on 1.5 T vs. 7 T, in the mid-brain region, were less than one voxel, indicating a successful co-registration between the 1.5 T and 7 T images under these specific imaging parameter sets. On regional analysis, the central part of the brain showed minimal distortion, while inferior and frontal areas exhibited larger distortion due to proximity to air-filled cavities. We conclude that 7 T MR images of the central brain regions have comparable distortions to that observed on a 1.5 T MRI, and that clinical applications targeting structures such as the STN, are feasible with information-rich 7 T imaging

Failure analysis of an automotive shock absorber cup during manufacturing process

A failure investigation was conducted on an automotive shock absorber cup during the manufacturing process. Due to the complexity of the parts, the manufacturing is carried out through multi deep drawing operations. The occurrence of cracks over the hole-flanged edge of the cups was the major problem in the forming process which causes failure. To determine the causes of failure, a detailed method including microscopic and macroscopic inspections were carried out in this study. The mechanical behavior of test specimens was investigated by means of tensile tests and the material was characterized in terms of Vickers micro-hardness. As a result, it was observed that the quality of the cut surface associated with the material work hardening after each sequence of sheet forming is the principal causes of failure. The damage is governed by the generation of micro defects during the punching process. This damage develops further during the hole-flanging step

Compact model and identification process for friction induced damping in a rotational joint with flawed surfaces

International audienceIt is well known that bolted joints have significant influence on the dynamical behavior of assembled structures due to formation of damping. This paper focuses on damping caused by dry friction in a rotational joint. Friction can be either induced by micro-slipping or macro-slipping. This paper describes the design of a new experimental device intended to measure damping caused by friction and partial slip in rotational joints. An original method for measuring dissipated energy in rotational joints with plan-plan contact is proposed. This method is based on Lagrange formalism and allows to measure accurately forces and torques only with accelerometers. These techniques are available for very small displacements that occur in micro-slip and partial slip of surfaces in contact and are still available for large displacements (macro-slip). An analytical compact model based on the Greenwood model is studied. The experimental results and simulations used to quantify the dissipated energy in order to compute the damping ratio are presented and discussed