Probing combinatorial library diversity by mass spectrometry

The feasibility of a "massively parallel" mass spectrometric method for probing combinatorial library diversity is addressed theoretically for the example of computer-generated mass distributions of combinatorially synthesized peptide libraries containing between two and seven amino acids. We study the behavior of several "global" (integral) parameters of such mass distributions [Formula: see text] mass centroid, dispersion, skewness, and kurtosis. The centroid and dispersion are shown to carry information that may characterize the completeness of the synthetic effort. "Local" mass distribution parameters, e.g., "mass density" (number of peptides per mass interval), are also examined. The practical implementation and eventual limitations of such an approach are discussed as well.     

A 64-Channel Data Acquisition System for Heterodyne Interferometric Plasma Density Diagnostics

The backbone of the system is an eight-channel recording module based on a unique circuit of a precision phase detector with a resolution of <0.5 mrad at a 1-MHz carrier frequency and in a 0- to 500-kHz modulation band. The dynamic range of each channel of the recording module varies from –250 to +250 rad.     

Stability of nonlinear waves on the ideal liquid surface in a tangential electric field

The propagation of waves with arbitrary amplitudes on the free surface of the ideal dielectric liquid in a strong tangential electric field is considered. A dispersion relation for the evolution of small perturbations of a stationary wave profile of the surface of a liquid with a large permittivity is obtained using conformal variables. It is established that, irrespective of the wave geometry, the amplitudes of small-scale perturbations do not increase with the time, which is evidence for the stability of wave solutions.     

Vaporization of the components of nickel alloys in a vacuum induction furnace

When nickel alloys are smelted in a vacuum induction furnace, the challenge is to refine the metal and retain the alloying elements and the nickel. In the present work, a model is developed for the behavior of all the components of complex alloys during refining in a vacuum induction furnace. The limiting stage is assumed to be the transfer of the components to the gas phase. In that case, the flux of each alloy component to the gas phase is determined from the Langmuir equation. The model adequately predicts the evaporation of the components of complex nickel alloys during refining in a vacuum induction furnace. The proposed algorithm may be used to calculate the change in mass and composition of nickel alloys over time in the course of refining in a vacuum induction furnace of specific capacity, with specified residual pressure and temperature.     

Predicting the liquidus temperature of complex nickel alloys

The production of steel and alloys ends with the casting of metal in a mold. In casting an alloy, its liquidus temperature must be known. This is especially important in developing a smelting technology for nickel alloys with a large number of alloying elements. In the present work, a model is developed for predicting the liquidus temperature of complex nickel alloys. The regression coefficients of the equations describing the liquidus and solidus lines of binary systems are determined on the basis of literature data regarding the phase diagrams of binary nickel systems with different elements. With increase in the set of data regarding the regression coefficients from 21 to 27 elements, a broad spectrum of complex nickel alloys may be covered. When the model based on data for binary alloys is tested for experimental liquidus temperatures of complex nickel alloys, the conclusion is that the model permits the prediction of the liquidus temperature of such alloys with sufficient precision for practical purposes (±19.8°C).     

Pressure effect on the phase transformations and structure of an Al-12 at % Si alloy

Phase transformations of an Al-12 at % Si alloy have been studied by differential barothermal analysis at temperatures of up to 700°C in argon compressed to 100 MPa. Heating at a rate of 8°C/min under a pressure of 100 MPa has been shown to increase the temperature of the L → (Al) + Si eutectic transformation in the alloy by 4°C. After crystallization of the binary eutectic, the differential thermal analysis cooling curve showed an additional exothermic peak, corresponding to the decomposition of the aluminum-based solid solution (Al) at 547°C and precipitation of silicon particles in the nanometer range. A barothermal scanning cycle reduced numerical porosity characteristics of the alloy, except for the pore number density. The lattice parameter of silicon microparticles in the alloy approaches values in the literature, whereas that of nanoparticles is slightly greater. The lattice parameter of the aluminum remains unchanged during crystallization and cooling in compressed argon. The microhardness of the aluminum matrix of the alloy corresponds to that of pure aluminum.