Laser surface modification of a 13.5% Cr, 0.6% C steel

A 13.5% Cr, 0.6% C steel, with an initial microstructure of chromium carbides in a ferrite matrix, was heat-treated by scanning a high-power laser beam over the surface. The aim was to compare the physical and chemical properties produced by this type of selective surface treatment with those resulting from a conventional furnace desensitization and quench-hardening heat treatment. Surface heating homogenized the carbon originally bound in the carbides sufficiently to produce martensite, giving hardening to levels comparable with a conventional heat treatment. Chromium-rich zones, carbides and retained austenite were also detected in the heated microstructure. Surface melting produced complete homogenization of both carbon and chromium, which resulted in the retention of large amounts of austenite in the microstructure on cooling to room temperature. Subsequent refrigeration at — 196 °C transformed some of the austenite to martensite. Pitting corrosion and local reductions in hardness were observed adjacent to treated areas under certain conditions, due to precipitation of secondary carbides and elevated tempering, respectively.     

Digital image correlation techniques to investigate strain fields and cracking phenomena in asphalt materials

This paper is the outcome of a specific task group of the RILEM Technical Committee 241-MCD “Mechanisms of Cracking and Debonding in Asphalt and Composite Pavements”. The group on “Advanced Measurement Techniques” was established in 2011 to investigate DIC applications for non-destructive and non-contact measurements of strain fields during laboratory testing. The paper illustrates different DIC/optical flow applications in measuring strain distribution during laboratory testing. Specific applications of DIC for evaluating crack initiation and crack propagation in asphalt materials are presented.     

Membrane-assisted revelation of the spatial nanoarchitecture of dislocation networks

We propose a method of direct visualization of the spatial nanoarchitecture of dislocation networks which is based on etching away the regions with low density of structural defects from the bulk of GaN epilayers, keeping intact only the threading dislocations and a thin surface film pre-treated with low-energy Ar⁺ ions. The formation of nanometer-thick suspended membrane to which the dislocations are genetically attached provides conditions for the revelation of the spatial nanoarchitecture of dislocation networks using conventional scanning electron microscopy. Complementary monochromatic and panchromatic micro-cathodoluminescence images are presented.     

Synthesis of optical transparent and electrical conductive polymer/nanocarbon composite films by infiltration method

Optical transparent and electrical conductive (PMMA)/nanocarbon composite films can be prepared through the infiltration of the polymer between the carbon aggregates of a preformed percolation cluster. This cluster is prepared by Langmuir-Blodgett technique as a thick film (2-20 μm in thickness). The performed direct current electrical measurements have shown that PMMA/Multiwall Nanotubes present a lower electrical surface resistivity and a higher optical transmittance than PMMA/carbon nanoparticles composite films. Much simpler and cheaper than other methods, the infiltration method allowed us to prepare composite films with a 75% in transparency and 1 MΩ/square in surface electrical resistivity. The composite films prepared by infiltration method have a good adhesion to the glass substrates but in some specific conditions can be integrally removed as free-standing films.     

A new system for computer-aided preoperative planning and intraoperative navigation during corrective jaw surgery.

A new system for computer-aided corrective surgery of the jaws has been developed and introduced clinically. It combines three-dimensional (3-D) surgical planning with conventional dental occlusion planning. The developed software allows simulating the surgical correction on virtual 3-D models of the facial skeleton generated from computed tomography (CT) scans. Surgery planning and simulation include dynamic cephalometry, semi-automatic mirroring, interactive cutting of bone and segment repositioning. By coupling the software with a tracking system and with the help of a special registration procedure, we are able to acquire dental occlusion plans from plaster model mounts. Upon completion of the surgical plan, the setup is used to manufacture positioning splints for intraoperative guidance. The system provides further intraoperative assistance with the help of a display showing jaw positions and 3-D positioning guides updated in real time during the surgical procedure. The proposed approach offers the advantages of 3-D visualization and tracking technology without sacrificing long-proven cast-based techniques for dental occlusion evaluation. The system has been applied on one patient. Throughout this procedure, we have experienced improved assessment of pathology, increased precision, and augmented control.     

An evolutionary procedure for machine learning

We discuss an evolutionary procedure for machine learning and present in detail an application of this procedure to the control of a robot TURTLE; which, beginning from a state of total ignorance, is able to develop the ability to circumnavigate a variety of obstacles.     

High-resolution proton,carbon-13 and nitrogen-15 nuclear magnetic resonance studies of wheat proteins at high magnetic fields: Spectral assignments,changes with concentration and heating treatments of flinor gliadins in solution—comparison with gluten spectra

The first high-field and high-resolution proton, carbon-13 and nitrogen-15 nuclear magnetic resonance (n.m.r.) spectra of gliadin solutions are reported. Collective assignments are proposed based on ‘random coil’ chemical shifts and amino acid analysis of gliadins. Additional information from X-ray diffraction, photoacoustic spectroscopy, dielectric relaxation and electrophoretic measurements is considered in the interpretation of the n.m.r. spectra. Marked changes in the n.m.r. spectra of gliadin solution were observed with increasing concentration or temperature. An interpretation of these effects in molecular terms is proposed and the practical implications of n.m.r. measurements for wheat variety identification and correlation with rheological testing indicated. The relevance of the results to studies of glutens is also noted.     

Modification to the renneting functionality of casein micelles caused by nonionic surfactants

Nonionic emulsifiers of small molecular weight such as polysorbates are widely used in dairy products. Nevertheless, the mechanism of interaction between these surfactants and milk proteins is not yet fully understood. This work investigated the effect of Tween 20 on casein micelles by studying the renneting behavior of skim milk in the presence of different amounts of surfactant. The presence of Tween accelerated both the first and second phase of renneting in skim milk. The gel obtained showed a higher elastic modulus than that of a skim milk gel, but also showed similar brittleness. By varying the size of the surfactant (Tween 20 or Tween 80) as well as the colloidal state of the proteins in solution, it was possible to demonstrate that the surfactant did not have a direct effect on the activity of the enzyme, but rather had a direct effect on the casein micelles. The effect of surfactant on the gelation point was reduced by increasing surfactant size. The presence of Tween caused an increase in the size of the micelles without affecting their stability. In addition, Tween did not alter the amount of caseins free in the serum phase. These findings can contribute to improving our ability to custom design final structures in rennet-induced gels, though further studies are needed to fully understand the mechanism at play when casein micelles are enzymatically cleaved in the presence of nonionic surfactants of small molecular weight.