Resampling and deconvolution of linear time-of-flight records for enhanced protein profiling

We have developed a peak deconvolution strategy that is applicable to the full mass range of a time-of-flight (TOF) spectrum. This strategy involves resampling a spectrum to create a time series that has equal peak widths (in time) across the entire spectrum, and then using the deconvolution filters we have previously described. We use this technique to deconvolve the protein mass spectra for blood serum and cell lysates acquired on three separate TOF instruments. Following deconvolution, we resolve spectral structures consistent with expected events such as multiply charged ions, matrix adducts and post-translational protein modifications. The deconvolution procedure produces a 40% improvement in the resolution and enhanced experimental sensitivity over the full length of the linear TOF record, up to m/z 150 000. This approach is particularly appropriate for automated data analysis and peak detection in dense TOF spectra.     

The spherical p-harmonic eigenvalue problem in non-smooth domains

We prove the existence of p-harmonic functions under the form $u(r,\sigma )=r^{?\beta }\omega (\sigma )$ in any cone $C_S$ generated by a spherical domain S and vanishing on $?C_S$. We prove the uniqueness of the exponent β and of the normalized function ω under a Lipschitz condition on S.     

The design of a continuous reactor for fluorous biphasic reactions under pressure and its use in alkene hydroformylation

A reactor, into which all reagents can be fed continuously and from which the reaction mixture can be continuously removed to a gravity separator, where product can be continuously removed and the catalyst phase recycled to the reactor, has been constructed and used for the hydroformylation of alkenes in fluorocarbon solvents.     

Loss of Pendimethalin in Surface Runoff from Plots Untilled and Tilled with Tobacco

Abstract

The loss of pendimethalin (N-(ethylpropyl)-2,6-dinitro-3,4-xylidine), a selective herbicide in runoff water was determined on sandy-clay-loam soil plots cultivated with tobacco in relation with the use of ammonium nitrate limestone as fertelizer, for a period of two years, 1990 and 1991. The surface slope of plots was 11% and the use of fertilizer decreased the soil erosion from a value 617 g/m²to 320 g/m². The runoff of surface waters were between 16-24% of the rainfall amounts. Reduction in pendimethalin in waterways results from water loss by infiltration, sediment loss, and by attachment adsorption on vegetative and organic matter. Surface runoff levels were highest for the first runoff event after herbicide application, 1.5 g/10 m² and initial concentrations were related to the time lapse between herbicide application and the date of the first run-off event. Maximum concentrations were 5.95 and 8.54 μg/L in 1990 and 1991 respectively. Persistence studies showed that pendimethalin concentration in runoff of 0.5 cm soil layer decreased by 88.2%, from 2.46 to 0.29 μg/g within 233 days, in 1990 and by 87.6%, from 2.42 to 0.30 μg/g within 235 days in 1991. After 310 day the concentration of pendimethalin was only 0.1 μg/g.     

Comparison of ISO-GUM and Monte Carlo methods for the evaluation of measurement uncertainty: application to direct cadmium measurement in water by GFAAS

The propagation stage of uncertainty evaluation, known as the propagation of distributions, is in most cases approached by the GUM (Guide to the Expression of Uncertainty in Measurement) uncertainty framework which is based on the law of propagation of uncertainty assigned to various input quantities and the characterization of the measurand (output quantity) by a Gaussian or a t-distribution. Recently, a Supplement to the ISO-GUM was prepared by the JCGM (Joint Committee for Guides in Metrology). This Guide gives guidance on propagating probability distributions assigned to various input quantities through a numerical simulation (Monte Carlo Method) and determining a probability distribution for the measurand.In the present work the two approaches were used to estimate the uncertainty of the direct determination of cadmium in water by graphite furnace atomic absorption spectrometry (GFAAS). The expanded uncertainty results (at 95% confidence levels) obtained with the GUM Uncertainty Framework and the Monte Carlo Method at the concentration level of 3.01 μg/L were ±0.20 μg/L and ±0.18 μg/L, respectively. Thus, the GUM Uncertainty Framework slightly overestimates the overall uncertainty by 10%. Even after taking into account additional sources of uncertainty that the GUM Uncertainty Framework considers as negligible, the Monte Carlo gives again the same uncertainty result (±0.18 μg/L). The main source of this difference is the approximation used by the GUM Uncertainty Framework in estimating the standard uncertainty of the calibration curve produced by least squares regression. Although the GUM Uncertainty Framework proves to be adequate in this particular case, generally the Monte Carlo Method has features that avoid the assumptions and the limitations of the GUM Uncertainty Framework.     

An approximation algorithm for the location of dairy enterprises under time constraints

The facility location problem constitutes a major part of the strategic planning of a dairy enterprise. The decision making process for such a long term investment is rather complicated, with many of the issues involved belonging to the NP – Hard class of algorithms and therefore the challenge for operational researchers who attempt to mathematically model the problem is significant. A number of models have appeared in the last few years in an attempt to find a solution to the problem. This paper introduces a model pertaining to saturated and competitive markets, which include a high investment risk as well as a small margin for incorrect decisions of the newcomers. Time is a crucial element, especially for sensitive products with a limited life span cycle. An approximation algorithm is used and the solution is then compared with the optimal one. Emphasis was given to the running time of the software program, both in the designing and the implementation of the algorithm.     

A Cu/Pt near-surface alloy for water-gas shift catalysis

The primary route to hydrogen production from fossil fuels involves the water-gas shift (WGS) reaction, and an improvement in the efficiency of WGS catalysts could therefore lead to a major leap forward in the realization of hydrogen economy. On the basis of a combination of high-resolution scanning tunneling microscopy, X-ray photoelectron spectroscopy, and density functional theory (DFT) calculations, we suggest the existence of a new thermodynamically stable Cu/Pt near-surface alloy (NSA). Temperature-programmed desorption and DFT reveal that this Cu/Pt NSA binds CO significantly more weakly than does Pt alone, thereby implying a considerable reduction in the potential for CO poisoning of the Cu/Pt NSA surface as compared to that of pure Pt. In addition, DFT calculations show that this Cu/Pt NSA is able to activate H2O easily, which is the rate-determining step for the WGS on several metal surfaces, and, at the same time, to bind the products of that reaction and formate intermediates rather weakly, thus avoiding possible poisoning of the catalyst surface. The Cu/Pt NSA is thus a promising candidate for an improved WGS catalyst.     

Heavy-metal-ion capture, ion-exchange, and exceptional acid stability of the open-framework chalcogenide (NH(4))(4)In(12)Se(20)

The hydrothermal synthesis of the purely inorganic open-framework indium selenide (NH(4))(4)In(12)Se(20) (1) is reported. Compound 1 exhibits a unique three-dimensional open-framework structure. The framework of 1 shows an unusual, for a chalcogenide compound, rigidity arising from the unprecedented connection mode of its building blocks. Compound 1 possesses ion exchange capacity for Cs(+), Rb(+), NH(4) (+), but it has selectivity against Na(+) and Li(+). It also showed exceptional stability in relatively concentrated hydrochloric acid. Ion exchange of 1 with hydrochloric water solutions can produce its solid acid analogue H(2)(NH(4))(2)In(12)Se(20). The maximum cation-exchange capacity of 1 was found equal to two equivalents per mol, which is consistent with an exchange mechanism taking place in the 1D-channels formed by the largest cavities. In addition, 1 can do ion-exchange with heavy-metal ions like Hg(2+), Pb(2+), and Ag(+). The capacity of 1 to clean water solutions from heavy-metal ions was preliminarily investigated and found very high. Specifically, 1 can remove 99.9 % of Hg(2+), 99.8 % of Ag(+), and 94.9 % of Pb(2+) from aqueous solutions of each of these ions. Using different synthetic conditions, we isolated compound (NH(4))(2)In(12)Se(19) (2), which also has as good an acid stability as 1, but no ion-exchange properties. Overall, this work provides new hydrothermal synthetic approaches for isolation of all-inorganic open-framework chalcogenides.