Structure development during flow of polyblends containing liquid crystalline polymers

The microstructure development during capillary flow of polyblends containing Liquid Crystalline Polymers (LCPs) was studied. In the present investigation the wholly aromatic LCP constituent was the minor phase suspended in polycarbonate (PC), poly(butyleneterephthalate) (PBT) or Nylon 6 (N-6), in addition to previously studied amorphous nylon matrix Experimental results showed that the viscous forces acting at the components' interface are predominating the elongational deformation and the resulting structure development of the LCP phase. In cases where the viscosity of the suspending matrix was higher than the LCP one (PC, amorphous nylon) scanning electron micrographs indicated that fibrillar structure developed. In cases where the viscosity of the matrix polymers was lower than the LCP suspended phase, fibrous structures developed only at very high shear rates. Due to velocity rearrangement effects at the capillary exit a skin core morphology was observed. Since the polymers viscosity depends both on shear rate and temperature, the in situ composite structure development depends on the specific processing methods and conditions that the LCP containing polyblends experience.     

Properties of type K expansive cement of pure components I. Hydration of unrestrained paste of expansive component — Results

A mixture of $\text{C}{}_4\text{A}{}_3\text{S}\text{, C}\text{S}\text{H}{}_2\text{and CH}$, in stoichiometric ratio to form ettringite only was paste hydrated at temperatures between 20–50°C. Unrestrained specimens were tested for expansion, porosity, strength and hydration at different times. Expansions started at a critical degree of hydration α_cr, at which total porosity was minimum and strength was maximum. Raising curing temperature reduced α_cr and enhanced expansion and total porosity. Mercury intrusion porosimetry revealed a bimodal pore size distribution.     

Analysis and Automatic Classification of Breath Sounds

Analysis of breath sounds (auscultation) is an important part of the diagnosis of pulmonary diseases. An automatic breathsounds classification scheme is suggested. Types of normal and abnormal breath sounds are classified, with the goal of providing the physician with a diagnostic assist device. The classification is performed in two levels. The first level is based on the linear prediction coefflcients, and the second level on energy envelope features. Seven types of breath sounds were classified. Out of 105 trials, the system exhibited only five errors The system can be implemented on a microprocessor and thus can be offered as a low-cost clinical instrument.     

Tribological and Corrosion Behavior of Vacuum Plasma Sprayed Ti-Zr-Ni Quasicrystalline Coatings

This investigation deals with a study of the friction, wear, and corrosion behavior of vacuum plasma sprayed quasicrystalline (QC) Ti_41.5Zr_41.5Ni₁₇ coatings. During pin on disc experiments, a change in the mode of wear has been found to occur with corresponding changes in normal load and sliding velocity. The low thermal conductivity of quasicrystals and its brittleness play a vital role in determining the friction and wear behavior of such materials. When these coatings are subjected to rubbing for a longer period of time, wear occurs by subsurface crack propagation, and subsequent delamination within the coated layer. By comparing the QC to its polycrystalline counterpart during potentiodynamic measurements according to ASTM G 31, higher currents were found over the whole range of potentials for QC when immersed in 1 M HCl solution. This article is an invited paper selected from presentations at the 2007 International Thermal Spray Conference and has been expanded from the original presentation. It is simultaneously published in Global Coating Solutions, Proceedings of the 2007 International Thermal Spray Conference, Beijing, China, May 14-16, 2007, Basil R. Marple, Margaret M. Hyland, Yuk-Chiu Lau, Chang-Jiu Li, Rogerio S. Lima, and Ghislain Montavon, Ed., ASM International, Materials Park, OH, 2007.     

A Model-Theoretic Approach for Recovering Consistent Data from Inconsistent Knowledge Bases

One of the most significant drawbacks of classical logic is its being useless in the presence of an inconsistency. Nevertheless, the classical calculus is a very convenient framework to work with. In this work we propose means for drawing conclusions from systems that are based on classical logic, although the information might be inconsistent. The idea is to detect those parts of the knowledge base that cause the inconsistency, and isolate the parts that are recoverable. We do this by temporarily switching into Ginsberg/Fitting multivalued framework of bilattices (which is a common framework for logic programming and nonmonotonic reasoning). Our method is conservative in the sense that it considers the contradictory data as useless and regards all the remaining information unaffected. The resulting logic is nonmonotonic, paraconsistent, and a plausibility logic in the sense of Lehmann.     

Mechanisms of Fabric Reinforcement of Cement Matrices

The present paper discusses the mechanisms involve in fabric‐cement composites focusing on the effects of fabric geometry and the properties of the yarns. It was found that the geometry of a given fabric could enhance the bonding and enable one to obtain strain hardening behavior from low modulus yarn fabrics, due to the special shape of the yarn induced by the fabric. On the other hand, variations of the geometry in a fabric could drastically reduce the efficiency, resulting in a lower strengthening effect of the yarns in the fabric, relative to single yarns not in a fabric form. Therefore, in cement composites the fabrics can not be viewed simply as a means for holding together continuous yarns to be readily placed in the matrix, as is the case in composites with polymer matrix.     

Mechanical behavior of reinforced polyurethane foams

The mechanical behavior of three-phase reinforced polyurethane (PU) foam composites was investigated. Chopped-glass fibers, glass beads, and graphite powder were used as reinforcing materials. Emperimental results indicated that chopped-glass fibers enhance the foam mechanical properties in tension, while glass beads and graphite powder tend to improve the mechanical properties in compression. Microscopical observations revealed that the reinforcing filler location is within the cell walls acting as a matrix reinforcement. A modified Kerner equation, based on a model that assumes the superposition of a porous matrix and a rigid particulate filler, was compared with measured elastic moduli of the three-phase composite foams.     

Calmodulin regulation of calcium stores in phototransduction of Drosophila

Phototransduction in Drosophila occurs through the ubiquitous phosphoinositide-mediated signal transduction system. Major unresolved questions in this pathway are the identity and role of the internal calcium stores in light excitation and the mechanism underlying regulation of Ca2+ release from internal stores. Treatment of Drosophila photoreceptors with ryanodine and caffeine disrupted the current induced by light, whereas subsequent application of calcium-calmodulin (Ca-CaM) rescued the inactivated photoresponse. In calcium-deprived wild-type Drosophila and in calmodulin-deficient transgenic flies, the current induced by light was disrupted by a specific inhibitor of Ca-CaM. Furthermore, inhibition of Ca-CaM revealed light-induced release of calcium from intracellular stores. It appears that functional ryanodine-sensitive stores are essential for the photoresponse. Moreover, calcium release from these stores appears to be a component of Drosophila phototransduction, and Ca-CaM regulates this process.     

An efficient synthesis of muscalure from jojoba oil or oleyl alcohol

A four-step synthesis of (Z)-9-tricosene (muscalure), a component of the pheromone of the housefly, from jojoba oil (or three-step from oleyl alcohol) by 3-carbon (or 5-carbon) unit elongation was developed in overall high yield. The sequence of reactions and the purity of the products could be easily followed, with relatively good accuracy, by NMR technique.