Thermodynamic Evaluation of the Phase Stability and Microstructural Characterization of a Cast B1914 Superalloy

The boron-carbon superalloys (BC alloys) were developed to reduce the carbon content of the alloys to less than 0.02 wt.% and increase the boron content to 0.1 wt.% in some Ni-based superalloys. In this study, we have used characterization techniques, such as DTA, XRD, SEM coupling, and thermodynamic calculation using Thermo-Calc software, to obtain information about the phase transformation reaction temperatures and the elemental compositions of the microstructural constituents encountered in the B1914 superalloy. The microstructure of the B1914 superalloy was composed of a gamma (γ) phase with a dendritic structure and gamma prime (γ′) phase with a cuboidal shape. Precipitates of γ′ and a lamellar eutectic, composed of γ/(Mo,Cr,Ni)₃B₂, were identified in the interdendritic region. The thermodynamic calculation results have shown to be a valuable tool for predicting the transformation temperature, such as liquidus, γ’ solvus, and incipient melting point. These transformations are important parameters used in casting simulation software for determining the heat treatment and welding repair conditions for parts made from this alloy.     

Signal processing aspects of fusion plasma broadband reflectometry

Microwave reflectometry is a radar technique utilized by nuclear fusion diagnostics to evaluate the plasma electron density distribution (density profile) and its local fluctuations in experimental devices, e,g., tokamaks. It exploits the fact that an electromagnetic wave launched into the plasma is reflected at the layer where the refractive index vanishes. By mixing the incident and reflected waves, a phase-modulated reflectometric signal is produced. In O-mode broadband reflectometry, the density profile is determined by sweeping the frequency of the incident wave, estimating the phase-rate of the reflectometric signal and computing its Abel inversion integral. In this paper, a stochastic nonlinear filtering approach is adopted for the estimation problem. The joint phase and phase-rate dynamics is modeled as a vector Gauss-Markov process from which only the first component is observed. A suboptimal nonlinear filter tailored to the features of the problem under study is developed and tested by simulation and applied to real data. This estimator exhibits significant advantages over the extended Kalman-Bucy filter, which is used in this work as a benchmark     

Chemical reagents as probes: Application to fish protein gels and detection of a cysteine TGase in hake

A new concept was applied to fish products. Chemical reagents targeting specific chemical bonds were incorporated in to gel products for assessing the importance of non-covalent (sodium dodecylsulphate, 1.0%, w/w), disulphide (dithiothreitol, 0.2%, w/w) or transglutaminase-catalyzed (N-ethylmaleimide, 0.2%, w/w) bonding. These reagents acting as chemical probes were applied to the study of sea bass and hake protein gels and the effect of MTGase (0.5%, w/w).These reagents were valuable for reaching conclusions. The action of an endogenous cysteine TGase in hake products was detected. It was found that frozen storage and protein denaturation are fundamental not only for explaining differences between raw materials, but also seem to favour a different action mode of MTGase in each raw material. Moreover, this study may help to improve processed products, for instance, the positive interaction between MTGase and the disruption of disulphide bonds in hake gels may find a useful application through incorporation of cysteine + MTGase.     

Antioxidant synergy of α-tocopherol and phospholipids

The prevention of oxidation of a refined sardine oil by α-tocopherol at 0.04%, by several phospholipids [phosphatidylcholine (PC), phosphatidylethanolamine (PE), and cardiolipin (CL)] at 0.5%, as well as by combinations of α-tocopherol with each phospholipid, was investigated. The evolution of the oxidation process during 1 mon at 40±2°C was followed by a series of methods, measuring peroxide value (PV), diene, triene, and polyene index, and absorbance at 430 nm, while α-tocopherol and phospholipid content were being monitoried. Among these indices, PV was found to be the most adequate to follow the process. PC was the most effective individual antioxidant as shown by the PV values obtained at the end of the storage period, which were 54.0, 83.4, 87.9, and 97.7 meq O₂/kg for PC, CL, PE, and α-tocopherol, respectively. The highest synergistic effect was obtained with a mixture of α-tocopherol and PE, and the second and third best by mixtures made with PC and CL, respectively. The corresponding PV values recorded at the end of the period were 27.0, 35.0, and 58.0 meq O₂/kg. The high degree of synergy between PE and tocopherol is probably due to the occurrence of a simultaneous antioxidant mechanism involving Maillard compounds.     

Determination of Young’s modulus in polyester-Al2O3 and epoxy-Al2O3 nanocomposites using the Digital Image Correlation method

Young’s modulus of nano-composite systems composed of unsaturated polyester and epoxy resins with alumina nanoparticles of different sizes has been experimentally estimated. The nanoparticles used were spherical alpha-Al₂O₃ having 30-40 and 200 nm in diameter. Young’s modulus was estimated using an inverse problem that is solved by means of the classical Levenberg-Marquardt technique. A cantilever beam under bending was used in the experiments and the experimental procedure was performed using the Digital Image Correlation method, which is a well-established optical-numerical method for estimating full-field displacement. Experimental results indicate that Young’s modulus increases with increasing nanoparticle volume fraction. Finally, the estimated Young’s moduli were compared with classical theoretical models, showing that the experimental results are in agreement with literature data.     

Morphological spelling strategies: developmental stages and processes

The spelling of many words in English and in other orthographies involves patterns determined by morphology (e.g., ed in past regular verbs). The authors report a longitudinal study that shows that when children first adopt such spelling patterns, they do so with little regard for their morphological basis. They generalize the patterns to grammatically inappropriate words (e.g., sofed for soft). Later these generalizations are confined to the right grammatical category (e.g., keped for kept) and finally to the right group of words (regular verbs). The authors conclude that children first see these spelling patterns merely as exceptions to the phonetic system and later grasp their grammatical significance. The study included two new measures of grammatical awareness, both involving analogies, that predicted success with spelling inflectional morphemes in later sessions.     

Effects of delays to cooling and wrapping on strawberry quality (cv. Sweet Charlie)

‘Sweet Charlie’ strawberries were wrapped with PVC polymeric film, and forced-air precooled after delays of 0, 6 or 8 hours at 30 °C to study the effect of delaying precooling on physical and chemical quality characteristics of the strawberry. Non-wrapped fruits were used as a control. Evaluations were performed after storage for one week at 1 °C plus one day at 20 °C. Delaying the precooling resulted in less attractive fruits and loss of quality characteristics. Wrapped strawberries maintained better appearance and quality than nonwrapped berries.