Investigation of beta-amyloid peptide by on-line high-performance liquid chromatography coupled to electrospray ionization mass spectrometry

beta(1-39) amyloid peptide is one of the components of the cerebral amyloid deposits that are characteristic of Alzheimer's disease. Solid-phase synthesis of this peptide resulted in a fairly complex crude product containing both the target peptide and a number of side products. High-performance liquid chromatography coupled to electrospray ionization mass spectrometry allowed rapid and reliable identification of both the desired peptide and most of the side products which were found to have relative molecular masses above and below that of the target peptide.     

Adsorption of Dispersants on Zirconia Powder in Tape-Casting Slip Compositions

This paper reports the extension of the more fundamental work of Tormey et al. on the effectiveness of a common dispersant (menhaden fish oil) and a model system (glycerol trioleate) to tape-casting slip formulation. The adsorption isotherms of the two adsorbates on doped zirconia from methyl ethyl ketone—ethanol solutions were measured by thermogravimetric analysis of solutions equilibrated with the powder surface. Viscosity decreased while sintered density increased in tape-cast samples prepared to dispersant concentrations corresponding to points along the adsorption isotherm in a way which follows the isotherm if binder competition for surface sites is considered.     

On replacement models via a fuzzy set theoretic framework

Uncertainty is present in virtually all replacement decisions due to unknown future events, such as revenue streams, maintenance costs, and inflation. Fuzzy sets provide a mathematical framework for explicitly incorporating imprecision into the decision making model, especially when the system involves human subjectivity. This paper illustrates the use of fuzzy sets and possibility theory to explicitly model uncertainty in replacement decisions via fuzzy variables and numbers. In particular, a fuzzy set approach to economic life of an asset calculation as well as a finite-horizon single asset replacement problem with multiple challengers is discussed. Because the use of triangular fuzzy numbers provides a compromise between computational efficiency and realistic modeling of the uncertainty, this discussion emphasizes fuzzy numbers. The algorithms used to determine the optimal replacement policy incorporate fuzzy arithmetic, dynamic programming (DP) with fuzzy rewards, the vertex method, and various ranking methods for fuzzy numbers. A brief history of replacement analysis, current conventional techniques, the basic concepts of fuzzy sets and possibility theory, and the advantages of the fuzzy generalization are also discussed     

Some theoretical and experimental aspects of built-in solar storage

The possibility of using a built-in storage solar water heater in Jordan has been investigated. Experimental and theoretical results were obtained using a 90 × 90 × 10 cm solar heater which was tilted at an angle of 30° to the horizontal.It was found that the efficiency of the built-in storage solar heater may reach as high as 78% with a maximum increase in the water temperature of 70°C and at low cost compared to the conventional flat plate collector. It is therefore expected that such solar system may be used to provide reasonably sufficient hot water in Jordan. Analytical solution, based on the assumption that the water temperature equals that of the plate, was used to solve the governing equations. While a numerical solution was used to solve the equations under the condition that the plate temperature is not equal to that of the water.It was found that the assumption of the temperature of the plate (T_p) is equal to the temperature of water (T_w) is only justifiable at early hours of operation in the morning.     

Structure,nucleation, growth and morphology of secondary carbides in high chromium and Cr-Ni white cast irons

Heat-treated high chromium and Cr-Ni white cast irons are widely used by the mining and mineral industries for impact and abrasion resistance. With certain heat treatments, Fe-Cr carbides are precipitated within the chromium- and carbon-rich austenitic matrix, thereby destabilizing the austenite which transforms substantially to martensite on subsequent cooling. The crystal structures of these carbides were determined indirectly by referring electron microprobe analyses of the austenitic matrix to the appropriate isothermal solid-state sections of the Fe-Cr-C phase diagram and directly by microprobe analyses of exposed secondary carbides. The nucleation, growth and morphology of these carbides were studied by a combination of selective removal of the austenitic matrix and subsequent scanning electron microscopy of the exposed carbides.     

Programmable shaping of femtosecond optical pulses by use of128-element liquid crystal phase modulator

Programmable shaping of femtosecond pulses by using a 128-element liquid crystal modulator to manipulate the phases of optical frequency components which are spatially dispersed within a grating-and-lens pulse shaping apparatus is described. This apparatus makes possible gray-level control of the spectral phases and allows modification of the pulse shape on a millisecond time scale under electronic control. Refinements in the design of the multielement modulator result in pulse shaping fidelity comparable to that which can be achieved with microlithographically fabricated masks. Several examples of pulse shaping operation, including pulse position modulation, programmable pulse compression, and adjustable cubic phase distortion, are described