Indentation Thermal Shock Test for Ceramics

This paper presents an indentation-quench method to determine the resistance of ceramics to thermal cycling. The method defines a critical quench temperature difference, Δ T _c, based on a criterion which includes a minimum amount of crack growth and a minimum fraction of growing cracks. The method is applied to three different materials, which are ranked according to the individual values of Δ T _c. The variation of ΔT_c with different indentation loads and indentation positions is investigated. This technique uses a small number of specimens, avoids subsequent mechanical testing, and provides information about the ΔT C of the materials. The effect of repeated cycling on crack extension is also discussed.     

Discrete Element Method Simulation of Effect of Aggregate Shape on Fragmentation of Particle Composite

How primary particles affect the fragmentation of particle composites using discrete element method simulation is described. Disk‐shaped composite particles consisting of large aggregate particles embedded in a matrix of smaller sand particles have been impacted against a solid surface at range of collision velocities. The results have been analyzed to determine whether the shapes of the aggregates in the mixture have an influence on the fragmentation of particle composites. It has been identified that the fracture depends on the aggregate shapes of the particle composites. Liberation degrees and particle size distributions have also been found to be controlled by the shape of the primary particles. Particle shapes have a remarkable influence on the fragmentation behavior of the specimen, especially at lower velocities.     

In vitro activity of Δ6 and Δ9 desaturases in hepatomas of different growth rates

The in vitro activity of Δ9- and Δ6-desaturases was determined in the microsomal fraction of C3H/S normal mouse liver, SS1K fast growing hepatoma, and SS1H slow growing hepatoma. These tumors are two different sublines of a spontaneous hepatoma transplanted in 1949 by J.W. Wilson, Brown University, Providence, R.I., into C3H/ST W: strain. The activity of the two enzymes showed a parallel decrease in the two studied hepatomas. These alterations could be attributed to a fundamental change in structure or function in the tumors. The fatty acid desaturase activity seems to be independent of cell division in malignant tissues.     

Une structure derivee de celle du spinelle la structure de Fe0.76 Yb2.16 S4

Single crystals of so-called “FeYb₂S₄ spinel” were prepared and their crystal structure was solved. The cubic cell, space group Fd3m, has a lattice constant $\text{a}\text{= 10.69}\text{A}\text{?}$. From X-rays determinations, its content is (Fe_0.76 Yb_2.16 S₄) × 8. Iron is divalent and ytterbium is trivalent. Ytterbium is in two series of octahedral sites, which are partially filled : 0.96 Yb and 0.04 ? on every 16d position, 0.12 Yb and 0.88 ? on every 16c position. Only 0.76 iron atom is in every 8a position of the spinel.     

Early steps on the in vivo incorporation of 1-14C-linoleic acid into liver lipids from normal and essential fatty acid deficient rats

Essential fatty acid (EFA) deficient rats were injected intraportally with a solution of 1-¹⁴C-linoleic acid during a 1 min period. Livers were quickly frozen, pulverized, and the lipids extracted and fractioned by thin layer chromatography. The incorporation of 1-¹⁴C-linoleic acid into liver lipids was measured. The results were compared with those previously obtained from normal rats. No significant differences were observed in the total radioactivity recovered from lipid extracts. While the distribution of radioactivity into the 1–2 diacylglycerol fraction remained unchanged in both groups of rats, in the EFA deficient rats the 1-¹⁴C-linoleic acid incorporation was actually directed to the phospholipid fractions instead of to the triacylglycerol fractions as was observed in the normal rats.     

CORBA for network and service management in the TINA framework

The Common Object Request Broker Architecture (CORBA) specification defines interfaces and services to support interoperability and distribution transparencies for building distributed applications. The Telecommunications Information Networking Architecture (TINA) defines a framework for development of service and network management applications which relies on the use of a distributed processing platform such as CORBA. This approach is presented in the article, which discusses also the interoperation with the current TMN infrastructure     

Analysis of Amadori compounds by high-performance cation exchange chromatography coupled to tandem mass spectrometry

High-performance cation exchange chromatography coupled to tandem mass spectrometry or electrochemical detection was found to be an efficient tool for analyzing Amadori compounds derived from hexose and pentose sugars. The method allows rapid separation and identification of Amadori compounds, while benefiting from the well-known advantages of mass spectrometry, such as specificity and sensitivity. Glucose- and xylose-derived Amadori compounds of several amino acids, such as glycine, alanine, valine, leucine/isoleucine, methionine, proline, phenylalanine, and glutamic acid, were separated or discriminated using this new method. The method is suitable for the analysis of both model reaction mixtures and food products. Fructosylglutamate was found to be the major Amadori compound in dried tomatoes (approximately 1.5 g/100 g) and fructosylproline in dried apricots (approximately 0.2 g/100 g). Reaction of xylose and glycine at 90 degrees C (pH 6) for 2 h showed rapid formation of xylulosylglycine (approximately 12 mol %, 15 min) followed by slow decrease over time. Analysis of pentose-derived Amadori compounds is shown for the first time, which represents a major breakthrough in studying occurrence, formation, and decomposition of these labile Maillard intermediates.     

Scatter correction of transmission near-infrared spectra by photon migration data: quantitative analysis of solids

The scope of this work is a new methodology to correct conventional near-infrared (NIR) data for scattering effects. The technique aims at measuring the absorption coefficient of the samples rather than the total attenuation measured in conventional NIR spectroscopy. The main advantage of this is that the absorption coefficient is independent of the path length of the light inside the sample and therefore independent of the scattering effects. The method is based on time-resolved spectroscopy and modeling of light transport by diffusion theory. This provides an independent measure of the scattering properties of the samples and therefore of the path length of light. This yields a clear advantage over other preprocessing techniques, where scattering effects are estimated and corrected for by using the shape of the measured spectrum only. Partial least squares (PLS) calibration models show that, by using the proposed evaluation scheme, the predictive ability is improved by 50% as compared to a model based on conventional NIR data alone. The method also makes it possible to predict the concentration of active substance in samples with other physical properties than the samples included in the calibration model.     

Least-squares support vector machines modelization for time-resolved spectroscopy

By use of time-resolved spectroscopy it is possible to separate light scattering effects from chemical absorption effects in samples. In the study of propagation of short light pulses in turbid samples the reduced scattering coefficient and the absorption coefficient are usually obtained by fitting diffusion or Monte Carlo models to the measured data by use of numerical optimization techniques. In this study we propose a prediction model obtained with a semiparametric modeling technique: the least-squares support vector machines. The main advantage of this technique is that it uses theoretical time dispersion curves during the calibration step. Predictions can then be performed by use of data measured on different kinds of sample, such as apples.