Sperm motility and morphology as changing parameters linked to sperm count variations

Variations in semen analyses of 177 males over a 1 year period were assessed. The average means of total counts, motility, morphology, total motile count and non-motile % were determined for 5 classes of patients ranging from azoospermic to normospermic. Positive relationships between a falling sperm count, a decrease in motility and total motile counts were seen. Also, increasingly, abnormal forms were found with lower sperm counts.     

Word-identification priming for ignored and attended words

Three experiments examined contributions of study phase awareness of word identity to subsequent word-identification priming by manipulating visual attention to words at study. In Experiment 1, word-identification priming was reduced for ignored relative to attended words, even though ignored words were identified sufficiently to produce negative priming in the study phase. Word-identification priming was also reduced after color naming relative to emotional valence rating (Experiment 2) or word reading (Experiment 3), even though an effect of emotional valence upon color naming (Experiment 2) indicated that words were identified at study. Thus, word-identification priming was reduced even when word identification occurred at study. Word-identification priming may depend on awareness of word identity at the time of study.     

Finite element study of the fibre–matrix interface behaviour of [10°/90°] laminated composites under tensile loading

A three-dimensional unit cell has been developed and modelled using the finite element method to investigate the interface failure behaviour of SiCf/Si3N4 composites under tensile loading at room and elevated temperatures. The model idealizes the composite as a regular rectangular array of fibres in 0° and 90° orientations embedded in the matrix. It introduces three-dimensional contact elements between the fibre and the matrix to simulate the interface conditions between the two phases. Slippage between 0° and 90° layers is also considered by introducing another set of contact elements at the layer separation planes. Two interface conditions, namely, infinitely strong and weakly bonded, are considered to establish the correlation with the experimental data. To simulate the weak interface, the fibre and the matrix are assumed to slide over one another with shear stress through the Coulomb mechanism. The same assumption has been adopted for the layer separation planes. A finite element model utilizing these concepts has been developed. Stress–strain behaviour and the local stress distributions at various ambient temperatures within the unit cell, are presented. The investigation has also been extended to include the effects of residual stresses in the finite element model. It is shown that the model yields results that correlated reasonably well with the experimental data. © 1998 Kluwer Academic Publishers     

Anisotropic behaviour of semiconducting tin monosulphoselenide single crystals

Single crystals of ternary mixed compounds of group IV-VI in the form of a series, SnS_xSe_1-x (wherex = 0, 0.25, 0.50, 0.75 and 1), have been grown using direct vapour transport technique. The grown crystals were characterized by the X-ray diffraction analysis for their structural parameter determination. All the grown crystals were found to be orthorhombic. The microstructure analysis of the grown crystals reveals their layered type growth mechanism. From the Hall effect measurements Hall mobility, Hall coefficient and carrier concentration were calculated with all crystals showingp-type nature. The d.c. electrical resistivity measurements perpendicular toc-axis (i.e. along the basal plane) in the temperature range 303–453 K were carried out for grown crystals using four-probe method. The d.c. electrical resistivity measurements parallel to c-axis (i.e. perpendicular to basal plane) in the temperature range 303–453 K were carried out for the same crystals. The electrical resistivity measurements showed an anisotropic behaviour of electrical resistivity for the grown crystals. The anisotropic behaviour and the effect of change in stoichiometric proportion of S and Se content on the electrical properties of single crystals of the series, SnS_xSe_1-x (wherex = 0, 0.25, 0.50, 0.75 and 1), is presented systematically.     

Numerical and Experimental Studies of Substrate Melting and Resolidification during Thermal Spraying

A good understanding of melting and resolidification of the substrate will help us to achieve better bonding. Anumerical model is developed to investigate the solidification of the droplet, and melting and resolidification of thesubstrate. The molybdenum     

The solidification of metal-matrix particulate composites

The simplicity, economy and flexibility of solidification processes make them attractive methods for the production of particle-reinforced metal-matrix composites. At present, however, there is limited understanding of the phenomena occurring during solidification of these advanced materials. Nucleation and refinement of crystalline phases, physical and chemical interactions between dispersed particles and solidifying interfaces, and buoyancy-driven movement of the particles are areas where a knowledge base is beginning to be formed. Ultimately, the understanding of solidification processes in metal-matrix composites must become complete enough that microstructures can be tailored for specific applications.     

A pictorial index mechanism for model-based matching

We are currently developing unified query processing strategies for image databases. To perform this task, model-based representations of images by content are being used, as well as a hierarchical generalization of a relatively new object-recognition technique called data-driven indexed hypotheses. As the name implies, it is index-based, from which its efficiency derives. Earlier approaches to data-driven model-based object recognition techniques were not capable of handling complex image data containing overlapping, partially visible, and touching objects due to the limitations of the features used for building models. Recently, a few data-driven techniques capable of handling complex image data have been proposed. In these techniques, as in traditional databases, iconic index structures are employed to store the image and shape representation in such a way that searching for a given shape or image feature can be conducted efficiently. Some of these techniques handle the insertion and deletion of shapes and/or image representations very efficiently and with very little influence on the overall system performance. However, the main disadvantage of all previous data-driven implementations is that they are main memory based. In the present paper, we describe a secondary memory implementation of data-driven indexed hypotheses along with some performance studies we have conducted.     

Steady-state methanation kinetics over a Ni/Al2O3 catalyst

Extensive kinetic data for the methanation reaction over a Ni/Al₂O₃ catalyst were obtained in a specially designed gradientless reactor operating at steady state. The reactor pressure was 101.3 kPa, and three temperatures were used, namely, 503, 513 and 523 K. The following three-parameter phenomenological model based on a proposed Langmuir-Hinshelwood mechanism adequately describes the data: r = L² K₃ K₄^0.5 k₅ P^0.5H₂ Pco/ [1 + K₃ (k₅ / k₆)Pco + K₄^0.5 P^0.5H₂ ]² With dissociative adsorption of hydrogen and hydrogen-assisted dissociation of adsorbed carbon monoxide, the postulated mari is the CH surface group, and the rds is the hydrogenation of the surface CH group.