Martensitic phase transformations in Ni–Ti-based shape memory alloys: The Landau theory

We present a simple Landau free energy functional for cubic-to-orthorhombic and cubic-to-monoclinic martensitic phase transformations. The functional is derived following group–subgroup relations between different martensitic phases – tetragonal, trigonal, orthorhombic and monoclinic – in order to fully capture the symmetry properties of the free energy of the austenite and martensite phases. The derived free energy functional is fitted to the elastic and thermodynamic properties of NiTi and NiTiCu shape memory alloys which exhibit cubic-to-monoclinic and cubic-to-orthorhombic martensitic phase transformations, respectively.     

Study of shrinkage porosity in spheroidal graphite cast iron

This study aims at identifying the relationship between the shrinkage cavities and the solidification structure in spheroidal graphite cast iron. Cast samples specially designed to contain shrinkage cavities were used. The solidification macrostructure was revealed using the Direct Austempering After Solidification method, while the solidification microstructure was revealed by using colour etching. At the midsection of the pieces, the shrinkage cavities and the solidification structure were observed jointly. The study showed that the classification of shrinkage porosity found in literature does not correspond to the ductile iron solidification model recognized by most of the scientific community. Early solidification models, and therefore shrinkage formation mechanisms, were proposed in instances when there was not a thorough knowledge of the morphology of the solid phases during solidification. Nowadays, defects formation mechanisms can be described with higher accuracy. Therefore, an updated classification of shrinkage porosity for spheroidal graphite iron is proposed.     

Multiwavelength all-optical TDM switching using a semiconductoroptical amplifier in a loop mirror

We report simultaneous all-optical switching of multiple wavelengths using an optical loop mirror with an asymmetrically placed semiconductor optical amplifier. Switching is shown for 14-wavelength channels (across 14-nm bandwidth) with switching contrast of 10-23 dB     

Palladium‐Catalyzed [2+1] Cycloadditions Affording Vinylidenecyclopropanes as Precursors of 7‐Membered Carbocycles

Palladium(II) acetate in association with secondary phosphine oxides provides an efficient catalytic system for [2+1] cycloadditions starting from oxanorbornene derivatives and tertiary propargyl esters giving rise to vinylidenecyclopropanes. This reaction is specific to bidentate phosphinito–phosphinous acid ligands generated from secondary phosphine oxides. The [2+1] cycloaddition was found broad in scope with a high tolerance to various functional groups. Moreover, vinylidenecyclopropanes were straightforwardly converted into oxabicyclo[3.2.1]oct‐2‐ene derivatives through a palladium‐catalyzed ring‐expansion. Finally, the oxa bridge cleavage of oxatricyclic compounds yields functionalized 7‐membered carbocycles.

     

Etude de la resistivité de corps pulvérulents à base de carbone en fonction de la compression

Electrical resistance measurements were performed on different varieties of carbon blacks (Sterling Fr, MT, S, Black Pearls 2) under compression up to 660 kgf/cm² to determine the real resistivity of the carbon material. The general shape of the curves log p= - s log P are in good agreement with those reported by Mrozowski. Two theories have been proposed to explain the mechanism of the current flow through the particles. Holm's Contacts and the Tunnel effect between particles. The results for thermal blacks seem to agree with the first interpretation while the behaviour of the Channel blacks rather follows the second.     

Expected locations of digits and letters on ten-button keysets.

In an attempt to find out where people expect to find letters and numbers on each of six configurations of ten keys, 300 Ss were asked to write on keyset diagrams either letters or numbers in arrangements they felt were most natural. Results showed that people expect (1) to find numbers arranged in left-to-right order in horizontal rows starting with the top, (2) to find letters, two or three on a key, in the same arrangement, and (3) to find letters arranged in horizontal rows when numbers already on the keyset are so arranged, but when the numbers are arranged otherwise (e.g., in vertical columns) the Ss divided about equally in arranging the numbers in horizontal rows and in vertical columns. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Assessment of the austemperability of high-silicon cast steels through Jominy hardenability tests

The austemperability of seven high silicon cast steels with different alloy contents was characteri sed. The maximum round bar diameter that can be fully austempered changed from about 10?mm for an unalloyed steel to more than 70?mm for a low-alloy steel. The austemperability was calculated by applying a procedure based on a standard Jominy test and the characterisation of the microstructure along the Jominy sample. The method, which was validated experimentally, creates a relatively simple procedure to measure austemperability. Processing factors such as the ability of the salt bath to extract heat and the austempering temperature are accounted for the method. The metallographic study revealed the influence of microsegregation on hardenability, which is particularly important for cast steels.     

Development of low fat beef patty using <Emphasis Type="Italic">Cucurbita maxima</Emphasis> Duchesne defatted seeds flour paste

The present work aimed at evaluating the Cucurbita maxima Duchesne defatted seeds flour (CDSF) as fat replacer in beef patty. Pastes obtained from CDSF containing 60 and 72 % water were prepared and used to replace fat in beef patty at 25, 50, 75 and 100 % respectively. A control patty was processed using kidney fat from beef. The proximate composition, technological yield, textural and sensorial properties of different samples were evaluated. Results showed that CDSF contains 77.76/100 g proteins based on dried matter. Protein content of patty increased with fat substitution rates (FSR) from 18.82/100 g wet matter (WM) to 23.24/100 g WM respectively for the control (P0) and the sample in which fat was substituted at 100 % with the CDSF paste with a water content of 60 % (P460). The lipid content dropped with the increase in the fat substitution rate and water content of CDSF paste from 10.70/100 to 0.28/100 g WM respectively for the sample in which fat was substituted at 25 % with the CDSF paste with a water content of 60 % (P160) and the sample in which fat was substituted at 100 % with the CDSF paste containing 72 % water (P472). Similarly, hardness dropped from 54.78 N (P0) to 37.56 N (P472) respectively. The cooking yield increased significantly (p < 0.05) with the increase in the water content of the CDSF paste and the fat substitution rate. From the sensory analysis, patties with 75 and 100 % of FSR were the most accepted. Thus, the CDSF paste can be used in beef patty as a fat replacer to reduce the detrimental effect of animal fat consumption.     

Macro and microstructural characterisation of high Si cast steels – Study of microsegregation patterns

In this study the as-cast macro and microstructures of medium C – high Si cast steels of three different levels of alloying are characterised. The application of a colour-etching reagent sensitive to Si segregation effectively revealed the solidification macrostructure, showing that the patterns of macrostructure and microsegregation are governed by the initial precipitation of δ-ferrite dendrites. A study of microsegregation carried out using advanced EDS techniques showed that, for the studied chemical compositions, Si, Mn, Cr, Ni, Mo and Al tend to concentrate at the last liquid to solidify. Accordingly, effective partition coefficients of values below unity were calculated for all alloying elements tested. It was verified that the minimum local Si contents measured on the steels investigated were greater than 1.7%, value above the minimum value (1.5%) necessary to obtain carbide-free bainite after austempering.     

A facile,effective thermal crosslinking to balance stability and proton conduction for proton exchange membranes based on blend sulfonated poly(ether ether ketone)/sulfonated poly(arylene ether sulfone)

The development of hydrocarbon polymer electrolyte membranes with high proton conductivities and good stability as alternatives to perfluorosulfonic acid membranes is an ongoing research effort. A facile and effective thermal crosslinking method was carried out on the blended sulfonated poly (ether ether ketone)/poly (aryl ether sulfone) (SPEEK/SPAES) system. Two SPEEK polymers with ion exchange capacities (IECs) of 1.6 and 2.0 mmol g^?1 and one SPAES polymer (2.0 mmol g^?1) were selected to create different blends. The effect of thermal crosslinking on the fundamental properties of the membranes, especially their physicochemical stability and electrochemical performance, were investigated in detail. The homogeneous and flexible thermally-crosslinked SPEEK/SPAES membranes displayed excellent mechanical toughness (27–46 Mpa), suitable water uptake (<60%), high dimensional stability (swelling ratio < 15%) and large proton conductivity (>120 mS cm^?1) at 80 °C. The thermal crosslinking membranes also show significantly enhanced hydrolytic (<2.5%) and oxidative stability (<2%). Fuel cell with t-SPEEK/SPAES (1:2:2) membrane achieves a power density of 665 mW cm^?2 at 80 °C.