Kinetics of the oxidation of metals: Parallel circuit for point defects diffusion

A model is proposed for the oxidation of metals including both bulk crystal lattice diffusion and short-circuit diffusion paths. Assuming local equilibrium between point defects in the bulk and in grain boundaries, we obtain an effective parabolic rate constant k_eff=k_bulk [1+ exp-(H/RT],where H is the enthalpy for the reaction between point defects in the bulk and in short circuits, is the fraction of the short-circuit area, and T is temperature. In the case of the high-temperature oxidation of nickel coated with a thin film of vanadium pentoxide, this model yields to a rate law with a critical oxygen pressure P _c. The nickel vanadium oxide located in the short circuits of the growing oxide NiO is liquid below P_c, leading to a rapid short-circuit diffusion. Above this value, a vanadate precipitates and acts as diffusion blocks for migrating Ni ions.     

Virtual reconstruction of archeological vessels using expert priors and intrinsic differential geometry information

This paper presents a method to assist in the tedious task of reconstructing ceramic vessels from unearthed archeological shards (fragments) using 3D computer vision-enabling technologies. The method exploits the shards surface intrinsic differential geometry information (one of many possible tools) coupled with a series of generic models to produce a virtual reconstruction and rendition of what the original vessel may have looked like. Generic models are constructed based on a host of factors including expert historical knowledge of the period, provenance of the artifact, and site location. The generic models need not to be identical to the original vessel, but they must be within a geometric transformation of it in most of its parts. The method is suited for ceramic vessels with some relief (i.e., surface with molding, carving, or stamping), as this method exploits surface intrinsic features for alignment. The alignment of the shards against the generic model uses a novel set of 3D weighted curve moments. The transformation is computed from corresponding parabolic contours on the shard and the generic model. A distance error metric is used to access the accuracy of alignment of a fragment to a given generic vessel model. The method is also extendable to surface markings. For a vessel that has no relief, color information or surface breaks can be used for the alignment. The method is tested on a subset of 3D scanned Independence National Historical Park (INDE) ceramic artifacts and the generic models created by experts. This work is part of an ongoing research activity in computational archeology that exploits many different tools and features to help in the mending process. Only the use of surface differential geometry information is reported here. This aspect is complementary to various other tools reported elsewhere by us and others, such as surface breaks, texture, color, etc.     

New functional legume foods by germination: effect on the nutritive value of beans, lentils and peas

The effect of different conditions of germination at a semi-pilot scale on the content of available soluble sugars, alpha-galactosides, vitamins B₁ and B₂, and inositol phosphates of beans, lentils and peas have been studied. Results obtained indicated that germination modified the nutritional composition of legumes depending on the type of legume and germination conditions. The storage compounds present in dry seeds (alpha-galactosides and higher forms of inositol phosphates) decreased because they were hydrolysed to glucose, fructose, IP₄ and IP₃, compounds that can serve as a source of energy for the new plant. Vitamin B₂ suffered an important increase after germination whereas vitamin B₁ did not change significantly. To achieve legume flours with enhanced nutritive value, 6 days of germination in the presence of light for beans and lentils, and in darkness for peas can be suggested.     

Losses and Parasitic Torques in Electric Motors Subjected to PWM Waveforms

Some aspects of the theoretical performance of an electric motor, supplied by an unfiltered pulsewidth modulated (PWM) inverter are studied. The stator copper losses and the winding insulation lifetime are emphasized. An induction motor system is assumed and the creation of low-frequency parasitic torques are described. Their relative importance are estimated. It is shown that PWM supplies may have a negative impact on the motor performance and lifetime and can make a modification of the motor design more desirable than in the case where a ``simpler' inverter system is used.     

A hypothesis about the biological basis of expert intuition.

It is well established that intuition plays an important role in experts' decision making and thinking generally. However, the theories that have been developed at the cognitive level have limits in their explanatory power and lack detailed explanation of the underlying biological mechanisms. In this paper, we bridge this gap by proposing that Hebb's (1949) concept of cell assembly is the biological realization of Simon's (1974) concept of chunking. This view provides mechanisms at the biological level that are consistent with both biological and psychological findings. To further address the limits of previous theories, we introduce emotions as a component of intuition by showing how they modulate the perception-memory interaction. The idea that intuition lies at the crossroads between perception, knowledge, and emotional modulation sheds new light on the phenomena of expertise and intuition. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Changes in scopoletin concentration in cassava chips from four varieties during storage

BACKGROUND: The use of the root crop cassava (Manihot esculenta Crantz) is constrained by its rapid deterioration after harvesting. Chemical and spectroscopic examination earlier revealed the accumulation of the four hydroxycoumarins esculetin, esculin, scopolin and scopoletin derived from the phenylpropanoid pathway, during the time course of postharvest deterioration. In this investigation the scopoletin level in parenchymal samples of four cassava cultivars used in Benin, i.e. Kpaki kpika, Kpaki soan, Logoguesse kotorou and BEN 86052, was investigated by high‐performance liquid chromatography (HPLC). RESULTS: Presence was shown in all four varieties with a mean in fresh roots between 4.1 and 11.1 mg kg^?1 dry weight. A strong increase in the content of scopoletin was noticed after a peeling and drying process (6 days) for chip production, the mean content reaching 242.5 mg kg^?1 dry weight in the cultivar BEN 86052. After 3 months of storage this had decreased to 0.7 mg kg^?1 dry weight. CONCLUSION: Strong accumulation of scopoletin in cassava roots used for chip production in Benin is followed by a decrease in its concentration. Copyright © 2011 Society of Chemical Industry     

The contents of the neuro-excitatory amino acid β-ODAP (β-N-oxalyl-l-α,β-diaminopropionic acid), and other free and protein amino acids in the seeds of different genotypes of grass pea (Lathyrus sativus L.)

The free and protein amino acids of nine different genotypes of grass pea (Lathyrus sativus L.) seeds were analysed by HPLC with pre-column PITC (phenyl isothiocyanate) derivatisation. Among the free amino acids, homoarginine was quantitatively the most important (up to 0.8% seed weight) and stable while the neuro-excitatory amino acid β-ODAP (β-N-oxalyl-l-α,β-diaminopropionic acid) showed highest variation (0.02–0.54%) in the nine genotypes examined. Among protein amino acids, glutamic acid was quantitatively most significant, followed by aspartic acid, arginine, leucine, lysine and proline. The sulphur amino acid, methionine, showed the lowest concentration in all the L. sativus genotypes, and also in lentil (Lens culinaris) and in soybean (Glycine max) seeds analysed at the same time.     

Alternative to the Conradson carbon residue test

A rapid test has been developed for determination of the coke forming tendency of petroleum materials in the range < 0.1–50% coke residue. The test, identified as the microcarbon residue (MCR) method, produces the same results as the Conradson carbon residue test (ASTM D189-76). The MCR method requires only milligram quantities of sample, and permits simultaneous analysis of 4–15 samples, one of which can be a standard.     

Kinetics of free protein amino acids, free non-protein amino acids and trigonelline in soybean (Glycine max L.) and lupin (Lupinus angustifolius L.) sprouts

A contribution for a better nutritional knowledge of lupin (Lupinus angustifolius L. var. zapaton) and soybean (Glycine max L. var. merit and var. jutro) sprouts about free protein amino acids (FPAA), free non-protein amino acids (FNPAA such as β-N-oxalyl-l-α,β-diaminopropionic acid (β-ODAP), α-aminoadipic acid, γ-aminobutyric acid (GABA) and β-alanine) and trigonelline content has been carried out. Seeds were germinated at 20 °C and darkness during several days in order to obtain good appearance sprouts. The content of FPAA and FNPAA varied among species and varieties. FPAA increased dramatically during germination and the lowest concentrations were found for G. max L. var. jutro. Cys was not detected as FPAA in seeds and seedlings of both legumes. Asn was present in the highest amounts in soybean and lupin seedlings. The α-aminoadipic acid gliotoxin, which was not present in raw soybean seeds, appeared in low amounts during germination. Later stages of germination caused significant increases of β-alanine and GABA, amino acids with beneficial properties. Germination also affected the content of the multifunctional plant hormone trigonelline and slight changes were observed. Highest levels of FPAA, beneficial FNPAA and trigonelline were found at 4, 6 and 9 days of germination for G. max L. var. jutro, G. max L. var. merit and L. angustifolius L. var. zapaton, respectively. Furthermore, these selected germination conditions showed low levels of the gliotoxic α-aminoadipic acid ensuring nutritional safety of the studied seedlings.