A method for analysis and profiling of boron,carbon and oxygen impurities in semiconductor wafers by recoil atoms in heavy ion beams

A method based on identification of recoil atoms in heavy ion beams, by using a (ΔE, E) measuring system, is described. The two parameter (ΔE, E) spectra, obtained with the aid of a computer, shows a good separation between carbon and oxygen recoils originating from a 300 μ;m thick silicon wafer bombarded with a 70 MeV sulphur beam. Profiling depths 10–20 μm and sensitivities close to 10¹⁶ atoms/cm are estimated.     

Stabilizing Model Predictive Control of Hybrid Systems

In this note, we investigate the stability of hybrid systems in closed-loop with model predictive controllers (MPC). A priori sufficient conditions for Lyapunov asymptotic stability and exponential stability are derived in the terminal cost and constraint set fashion, while allowing for discontinuous system dynamics and discontinuous MPC value functions. For constrained piecewise affine (PWA) systems as prediction models, we present novel techniques for computing a terminal cost and a terminal constraint set that satisfy the developed stabilization conditions. For quadratic MPC costs, these conditions translate into a linear matrix inequality while, for MPC costs based on 1, infin-norms, they are obtained as norm inequalities. New ways for calculating low complexity piecewise polyhedral positively invariant sets for PWA systems are also presented. An example illustrates the developed theory     

High-Speed TOFMS Detection for Capillary Electrophoresis

A new, high-speed data acquisition system was tested for high storage rate time-of-flight mass spectrometry (TOFMS) detection in capillary electrophoresis (CE). For high spectral acquisition rates of 4 kHz, a spectral storage rate of 80 spectra s(-)(1) was achieved. The resulting detection limit was in the low amol range (10-25 amol) for continuous infusion investigations.     

Sulfate reduction in Lake Agmon, Israel

Lake Agmon, a newly reflooded water body in the southern part of the Hula valley is characterized by a clear phase period in winter with almost no blooms of phytoplankton. Dense macrobenthos and algal blooms form in the lake during summer and autumn. High primary production and chlorophyll-a concentrations were measured in April and during the summer of 1997. Fresh organic matter in the sediments from the degradation and decomposition of the blooms together with high sulfate concentrations, allowed microbial sulfate reduction to occur. Sediment cores taken from different sites (peat and marl) during various seasons in 1997, showed high sulfate reduction rates in June in the marl region, and in September in the peat region (842 and 2834 nmol SO(4)2- reduced ml(-1) day(-1), respectively). In February, corresponding to the development and decline of macrophytes and algal blooms, lower rates of sulfate reduction were recorded (11 nmol SO(4)2- reduced ml(-1) day(-1)). Sulfate reduction is limited by the supply of organic matter and is one of the major processes contributing to the mineralization of organic matter in this lake.     

Manganese mobilization and enrichment during soil aquifer treatment (SAT) of effluents, the Dan Region Sewage Reclamation Project (Shafdan), Israel

The composition of groundwater reclaimed from tertiary soil aquifer treatment systems reflects the dynamic processes taking place in the subsurface, between the infiltration basin and the production wells. At the end of year 2000, following more than a decade of operation, high Mn concentrations (2 micromol L(-1) < or = Mn < or = 40 micromol L(-1)) appeared in the reclaimed effluents of the Dan Region Sewage Reclamation Project (Shafdan), Israel. A mass balance indicates that the high Mn excess originated from the aquifer rocks, most likely following reduction of sedimentary Mn-oxides under suboxic conditions. The subsequent adsorption of the Mn2+ results in a slow Mn2+ front that advances in the direction of groundwater flow only when all the Mn2+ exchangeable sites are saturated. A retardation factor obtained from two independent estimates based on a simple reduction-adsorption-advection model yields a value of about 10. This explains the delayed appearance of the high Mn concentrations at a distance of only -500 m from the infiltration basin.     

Impact of peptide modifications on the isobaric tags for relative and absolute quantitation method accuracy

In this study, the impact of amino acid modifications on the accuracy of the iTRAQ (isobaric tags for relative and absolute quantitation) method was evaluated. MCF-7 breast cancer cells, cultured in the presence of 17β-estradiol and tamoxifen, were used as a model system. The cells were labeled and analyzed by reversed-phase liquid chromatography and pulsed Q dissociation ion trap tandem mass spectrometry detection. Database searching was performed by using various combinations of amino acid modification allowances, i.e, Lys/Tyr/Cys and amino terminal iTRAQ labeling, Lys methylation, acetylation and carbamylation, and Cys/Met oxidation. Other than the intended Lys/amino terminal iTRAQ labeling, such modifications occur as a result of either enzymatic or sample preparation related reactions and are typically ignored in quantitation analysis to minimize the rate of false-positive peptide identifications. The study revealed that the modifications with the greatest impact on protein identification and quantitation pertain to Lys and Tyr amino acid residues, that by enabling such modifications the number and type of identified proteins will change (by up to 10%), and that the rate of false-positive protein identifications can be maintained below an upper threshold of 5% if appropriate data filtering conditions are used. In addition, the interference of possible posttranslational modifications (i.e., phosphorylation) with iTRAQ quantitation was examined.