Passivity and corrosion behaviour of Ti-10Mo-4Zr and Ti-6Al-4V alloys after long-term ageing in Ringer’s solution at 37 °C

Journal of Solid State Electrochemistry - The influence of long-term ageing in the Ringer’s solution at 37 °C on the passivity and corrosion behaviour of Ti–10Mo–4Zr...     

Can we use the CO2 concentrations determined by continuous‐flow isotope ratio mass spectrometry from small samples for the Keeling plot approach?

A common method to estimate the carbon isotopic composition of soil‐respired air is to use Keeling plots (δ¹³C versus 1/CO₂ concentration). This approach requires the precise determination of both CO₂ concentration ([CO₂]), usually measured with an infrared gas analyser (IRGA) in the field, and the analysis of δ¹³C by isotope ratio mass spectrometry (IRMS) in the laboratory. We measured [CO₂] with an IRGA in the field (n = 637) and simultaneously collected air samples in 12 mL vials for analysis of the ¹³C values and the [CO₂] using a continuous‐flow isotope ratio mass spectrometer. In this study we tested if measurements by the IRGA and IRMS yielded the same results for [CO₂], and also investigated the effects of different sample vial preparation methods on the [CO₂] measurement and the thereby obtained Keeling plot results. Our results show that IRMS measurements of the [CO₂] (during the isotope analysis) were lower than when the [CO₂] was measured in the field with the IRGA. This is especially evident when the sample vials were not treated in the same way as the standard vials. From the three different vial preparation methods, the one using N₂‐filled and overpressurised vials resulted in the best agreement between the IRGA and IRMS [CO₂] values. There was no effect on the ¹³C‐values from the different methods. The Keeling plot results confirmed that the overpressurised vials performed best. We conclude that in the cases where the ranges of [CO₂] are large (>300 ppm; in our case it ranged between 70 and 1500 ppm) reliable estimation of the [CO₂] with small samples using IRMS is possible for Keeling plot application. We also suggest some guidelines for sample handling in order to achieve proper results. Copyright © 2008 John Wiley & Sons, Ltd.     

A Characterization of Mixed Unit Interval Graphs

We give a complete characterization of mixed unit interval graphs, the intersection graphs of closed, open, and half‐open unit intervals of the real line. This is a proper superclass of the well‐known unit interval graphs. Our result solves a problem posed by Dourado, Le, Protti, Rautenbach, and Szwarcfiter (Mixed unit interval graphs, Discrete Math 312, 3357–3363 (2012)).     

Non Thermal Plasma Functionalized 2D Carbon–Carbon Composites as Supports for Co Nanoparticles

Novel two-dimensional carbon–carbon composites made of carbon nanofibers (CNFs) supported on a carbon preform were functionalized by non thermal plasma treatment (room temperature, atmospheric pressure, humid air), before being used as supports for metallic cobalt nanoparticles. It was shown that the degree of functionalization of the carbon nanofibers depends on the plasma power input, the treatment time and the CNF loading. The size of the cobalt nanoparticles generated after subsequent reduction of the Co-containing plasma treated CNF/C composites under hydrogen flow seems to be independent of the amount of supported cobalt. Changes in surface characteristics were analyzed using thermogravimetric analyses coupled to a mass spectrometer, X-ray photoelectron spectroscopy analyses and Raman spectroscopy. Transmission electron microscopy was used to complementary characterize the final size, dispersion and location of the so generated Co nanoparticles.     

Direct Sensing of 5‐Methylcytosine by Polymerase Chain Reaction

The epigenetic control of genes by the methylation of cytosine resulting in 5‐methylcytosine (5mC) has fundamental implications for human development and disease. Analysis of alterations in DNA methylation patterns is an emerging tool for cancer diagnostics and prognostics. Here we report that two thermostable DNA polymerases, namely the DNA polymerase KlenTaq derived from Thermus aquaticus and the KOD DNA polymerase from Thermococcus kodakaraensis, are able to extend 3′‐mismatched primer strands more efficiently from 5 mC than from unmethylated C. This feature was advanced by generating a DNA polymerase mutant with further improved 5mC/C discrimination properties and its successful application in a novel methylation‐specific PCR approach directly from untreated human genomic DNA.     

Schwerl?slichkeit des neutralen oxalsauren Ammoniaks in Ammonsalzl?sungen

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