Preparation and in situ characterization of surfaces using soft landing in a Fourier transform ion cyclotron resonance mass spectrometer

Mass-selected peptide ions produced by electrospray ionization were deposited onto fluorinated self-assembled monolayer surfaces (FSAM) surfaces by soft landing using a Fourier transform ion cyclotron resonance mass spectrometer (FT-ICR MS) specially designed for studying interactions of large ions with surfaces. Analysis of the modified surface was performed in situ by combining 2-keV Cs+ secondary ion mass spectrometry with FT-ICR detection of the sputtered ions (FT-ICR-SIMS). Regardless of the initial charge state of the precursor ion, the SIMS mass spectra included singly protonated peptide ion, peptide fragment ions, and peaks characteristic of the surface in all cases. In some experiments, multiply protonated peptide ions and [M + Au]+ ions were also observed upon SIMS analysis of modified surfaces. For comparison with the in situ analysis of the modified surfaces, ex situ analysis of some of the modified surfaces was performed by 25-keV Ga+ time-of-flight-secondary ion mass spectrometry (TOF-SIMS). The ex situ analysis demonstrated that a significant number of soft-landed peptide ions remain charged on the surface even when exposed to air for several hours after deposition. Charge retention of soft-landed ions dramatically increases the ion yields obtained during SIMS analysis and enables very sensitive detection of deposited material at less than 1% of monolayer coverage. Accumulation of charged species on the surface undergoes saturation due to coulomb repulsion between charges at close to 30% coverage. We estimated that close to 1 ng of peptide could be deposited on the spot area of 4 mm2 of the FSAM surface without reaching saturation.     

Direct-dynamical Entanglement–Discord relations

In this article, by considering Bell-diagonal two-qubit initial states under local dynamics generated by the Phase Damping, Bit Flip, Phase Flip, Bit Phase Flip, and Depolarizing channels, we report some elegant direct-dynamical relations between geometric measures of Entanglement and Discord. The complex scenario appearing already in this simplified case study indicates that a similarly simple relation shall hardly be found in more general situations.     

Independence of EPR and PAP tests performed on resistance spot welding joints

In the present paper, the possible relationships among the variables of the potentiodynamic anodic polarisation (PAP) test and the electrochemical potentiokinetic reactivation (EPR) test, both performed on resistance spot welding joints of AISI 304 stainless steel, are investigated. Results show that PAP variables are statistically independent from those of EPR, which implies independence between the pitting corrosion behaviour and the degree of sensitisation of the material. Parameters from PAP test are dependent among them, but this association is found noisy since the current density along the passive zone is not exactly constant. The parameters from the EPR test are confirmed as very related, presenting a linear relationship and a high coefficient of determination.     

Groundwater Recharge Assessment in an Arid,Coastal, Middle Mountain Copper Mining District,Coquimbo Region,North-central Chile

Groundwater recharge processes operating in a portion of the western slope of the Chilean Coastal Cordillera (30°S) were assessed. The study takes advantage of the presence of the Cerro Brillador Mine (CBM), currently part of the Universidad de La Serena mining research center. Six factors—slope, solar exposure, drainage density, lineament density, geology and vegetation were characterized in a 12 km × 12 km area around the mine to identify the zones of greatest and least potential for groundwater recharge. The analysis indicates that approximately 66% of the total area presents favorable conditions for recharge. At a more local scale, the work focused on the CBM itself, an experimental facility where structural measurements in the interior and exterior of the mine, monitoring of the water level in the shaft, and sampling of mine water for chemical and isotopic composition were carried out. The chemical analysis highlighted the lack of acid drainage, despite the existence of pyrite (FeS₂) and copper-sulfate mineralization in the mine. The isotopic analysis showed that the groundwater has a similar signature to local precipitation. From this information, a simple conceptual model for the hydrogeology is proposed, in which precipitation rapidly recharges the mine along faults and joints with a preferential N-S strike, but is impounded by the Urrutia fault, which facilitates the storage of groundwater in the underground workings by acting as a flow barrier. A simple analysis suggests a recharge rate on the order of 5% of the average annual precipitation for the CBM area.

     

Geological risks in slag heaps of roofing slate in Spain

Abstract

Roofing slate exploitations in Spain are concentrated within the regions of Valdeorras and La Cabrera. These progressively increased their production in the early sixties, and generated great volumes of wastes, which are now deposited in slag heaps, and owing to their effect on the drainage system currently constitute a geological risk, similar to that which happened in the floods of 1976. These risks have been evaluated both qualitatively, through a cause-effect matrix, and quantitatively following the methodology of the Master Plan of California on geological risks. Corrective solutions have been studied in order to mitigate the actual risks, and protect the affected riverbeds. Future performance measures have also been taken to minimize the wastes produced, and relocate them on suitable slag heaps, and even re-use them     

Uncertainty Measures in Expert Systems

Abstract: In classic logic, premises, conclusions, and rules are treated deterministically, i.e., they are considered as either true or false. However, when dealing with reality, one finds that all these elements must be considered as uncertain. Thus classic logic must be extended to cover real situations. One possible extension is given by uncertainty measures together with aggregation formulas that combine the uncertainty of premises with that of the rules to obtain the uncertainty of conclusions. This paper describes different uncertainty measures, giving the physical meaning of the implied axioms and their limitations, illustrated by some examples. Finally, a classification of some of the well-known uncertainty measures, such as belief and plausibility functions, probabilities, necessities, and possibilities, is given.     

Automatic recognition of hematite grains under polarized reflected light microscopy through image analysis

The recognition of hematite grains is an intermediate task that aids the texture characterization of iron ores. Hematite is a strongly anisotropic mineral. Thus, the combined use of a polarizer and an analyzer in reflected light microscopy (RLM) can be used to obtain images that present sufficient contrast to differentiate grains. The present work proposes a methodology for recognizing hematite grains in images obtained with RLM. Three images per field are acquired in different conditions: without polarization in common bright field arrangement; and with polarization under two symmetrical polarizer/analyzer angles. These images are automatically registered. Then, the hematite grains are recognized through a modified region growing segmentation method based on reflectance and textural information. An optimal value for the polarization angle was determined. The results are promising. The vast majority of grains was correctly recognized. The automatically segmented images were compared to edited versions in which all crystals were correctly discriminated. A statistical comparison of crystal size and shape showed no statistical differences, to within 99% confidence, between automatic and edited segmentation results.     

Electrochemical phagemid assay for the specific detection of bacteria using Escherichia coli TG-1 and the M13KO7 phagemid in a model system

We describe a reporter phagemid system for the specific amperometric detection of bacteria. We constructed a phagemid a bacteriophage containing a bacterial plasmid using the M13KO7 helper phage and a commercial plasmid, pFLAG-ATS-BAP, which contains a gene encoding for a reporter enzyme, alkaline phosphatase. In the bacteria, the enzyme reacts with the substrate, p-aminophenyl phosphate, in the periplamic space that separates the outer plasma membrane from the cell wall. Thus, the activity of the reporter enzyme can be measured directly in an electrochemical cell without further treatment. The product of the enzymatic activity, p-aminophenol, diffuses out and is oxidized at the working electrode with an applied potential of 220 mV vs the reference electrode Ag/AgCl. The lower detection limit was 1 cfu/mL E. coli TG1 in less than 3 h in a very specific manner. The use of plasmid alkaline phosphatase as the reporter increased the sensitivity by 10-fold over our earlier electrochemical lytic phage method. Such a system can be used for the rapid detection of any strain of bacteria using the appropriate bacteriophage and reporter gene.