Perturbative treatment of quasi-resonant proton neutralization at alkali-halide surfaces

A theoretical investigation of proton neutralization by proton scattering from several alkali-halide surfaces is presented. These systems are suitable for a perturbative treatment since no hydrogenic atomic shell is embedded in the valence band of the solid where the neutralizing electron originates, which is a necessary condition for fast convergence of the perturbative expansion for the neutralization probability. The perturbative interaction is modeled by a Fano-Anderson effective potential, and the dependence of the results on the properties of the systems (namely, the width of the valence band of the solid and its position relative to the discrete atomic level) and on the dynamics of the process (determined here by a single parameter which controls the duration of the interaction, i.e., the collision energy) are critically discussed.     

Chemical profile of meta-chlorophenylpiperazine (m-CPP) in ecstasy tablets by easy ambient sonic-spray ionization, X-ray fluorescence, ion mobility mass spectrometry and NMR

Meta-chlorophenylpiperazine (m-CPP) is a new illicit drug that has been sold as ecstasy tablets. Easy ambient sonic-spray ionization mass spectrometry (EASI-MS) and X-ray fluorescence spectrometry (XRF) are shown to provide relatively simple and selective screening tools to distinguish m-CPP tablets from tablets containing amphetamines (mainly 3,4-methylenedioxymethamphetamine (MDMA)). EASI-MS detects the active ingredients in their protonated forms: [m-CPP + H](+) of m/z 197, [MDMA + H](+) of m/z 194, and [2MDMA + HCl + H](+) of m/z 423 and other ions from excipients directly on the tablet surface, providing distinct chemical fingerprints. XRF identifies Cl, K, Ca, Fe, and Cu as inorganic ingredients present in the m-CPP tablets. In contrast, higher Cl concentrations and a more diverse set of elements (P, Cl, Ca, Fe, Cu, Zn, Pt, V, Hf, Ti, Pt, and Zr) were found in MDMA tablets. Principal component analysis applied to XRF data arranged samples in three groups: m-CPP tablets (four samples), MDMA tablets (twenty three samples), and tablets with no active ingredients (three samples). The EASI-MS and XRF techniques were also evaluated to quantify m-CPP in ecstasy tablets, with concentrations ranging from 4 to 40 mg of m-CPP per tablets. The m-CPP could only be differentiated from its isomers (o-CPP and for the three isomers p-CPP) by traveling wave ion mobility mass spectrometry and NMR measurements.     

A chip calorimetry-based method for the real-time investigation of metabolic activity changes in human erythrocytes caused by cell sickling

Journal of Thermal Analysis and Calorimetry - A new calorimetric technique is described which allows the measurement of metabolic heat rates in biological materials which are triggered by changes...