A chemotaxis chamber has been developed to analyze both the velocity and the directionality of individual T cells in gradients of high molecular mass molecules over long periods of time. Employing this chamber, it is demonstrated that syncytia induced by HIV in SUP-T1 cell cultures release two T cell chemoattractants with approximate molecular masses of 30 and 120 kDa. Neither uninfected single...

Cronobacter spp. are Gram-negative opportunistic food-borne pathogens and are known as rare but important causes of life-threatening neonatal infections. Rapid and reliable identification of Cronobacter species and their differentiation from phenotypically similar, nonpathogenic Enterobacter turicensis, Enterobacter helveticus, and Enterobacter pulveris have become increasingly important. We ev...

Setting appropriate bin sizes to aggregate hyphenated high-resolution mass spectrometry data, belonging to similar mass over charge (m/z) channels, is vital to metabolite quantification and further identification. In a high-resolution mass spectrometer when mass accuracy (ppm) varies as a function of molecular mass, which usually is the case while reading m/z from low to high values, it becomes...

Surface based mass spectrometric approaches fill an important niche in the mass analysis portfolio of tools. The particular niche depends on both the underlying physics and chemistry of molecule ejection as well as experimental characteristics. In this article, we use molecular dynamics computer simulations to elucidate the fundamental processes giving rise to ejection of organic molecules in a...

Recent advances in soft ionization techniques for mass spectrometry of polymeric materials make it possible to determine the mass of intact molecular ions exceeding 1 x 1 OS Da. Developments in high resolution mass spectrometers have additionally led to impressive advances in our ability to characterize polymers. The entire molecular mass distribution of a polymer sample can be accurately measu...

We quantitatively examine the significance of star formation triggered in the swept-up shell around an expanding H II region. If the swept-up molecular gas is sufficiently massive, new OB stars massive enough to repeat the triggering process will form in the shell. We determine the lower limit (Mthr) for the mass of the star that sweeps up the molecular gas, where at least one new star with mas...