“Lossless” compression of high resolution mass spectra of small molecules

Fourier transform ion cyclotron resonance (FTICR) provides the highest resolving power of any commercially available mass spectrometer. This advantage is most significant for species of low mass-to-charge ratio (m/z), such as metabolites. Unfortunately, FTICR spectra contain a very large number of data points, most of which are noise. This is most pronounced at the low m/z end of spectra, where data point density is the highest but peak density low. We therefore developed a filter that offers lossless compression of FTICR mass spectra from singly charged metabolites. The filter relies on the high resolving power and mass measurement precision of FTICR and removes only those m/z channels that cannot contain signal from singly charged organic species. The resulting pseudospectra still contain the same signal as the original spectra but less uninformative background. The filter does not affect the outcome of standard downstream chemometric analysis methods, such as principal component analysis, but use of the filter significantly reduces memory requirements and CPU time for such analyses. We demonstrate the utility of the filter for urinary metabolite profiling using direct infusion electrospray ionization and a 15 tesla FTICR mass spectrometer

Effect of CNFs content on the tribological behaviour of spark plasma sintering ceramic-CNFs composites

Alumina-carbon nanofibres (CNFs) and silicon carbide-CNFs nanocomposites with different volume fraction of CNFs (0-100vol.%) were obtained by spark plasma sintering. The effect of CNFs content on the tribological behaviour in dry sliding conditions on the ceramic-carbon nanocomposites has been investigated using the ball-on-disk technique against alumina balls. The wear rate of ceramic-CNFs nanocomposites decreases with CNFs increasing content. The friction coefficient of the Al 2O 3/CNFs and SiC/CNFs nanocomposites with high CNFs content was found to be significantly lower compared to monolithic Al 2O 3 and SiC due to the effect of CNFs and unexpectedly slightly lower than CNFs material. The main wear mechanism in the nanocomposite was abrasion of the ceramic and carbon components which act in the interface as a sort of lubricating media. The experimental results demonstrate that the addition of CNFs to the ceramic composites significantly reduces friction coefficient and wear rate, resulting in suitable materials for unlubricated tribological applications. © 2011.This work has been carried out with financial support of National Plan Projects MAT2006-01783 and MAT2007-30989-E and the Regional Project FICYT PC07-021. A. Borrell acknowledges the Spanish Ministry of Science and Innovation for her FPI Ph.D. grant. We would like to thank the people from Institute Technological of Materials (ITM) of the Polytechnic University of Valencia for helping us with the tribology experiments during A. Borrell's short stay in 2009.Borrell Tomás, MA.; Torrecillas, R.; Rocha, VG.; Fernandez, A.; Bonache Bezares, V.; Salvador Moya, MD. (2012). Effect of CNFs content on the tribological behaviour of spark plasma sintering ceramic-CNFs composites. Wear. 274:94-99. https://doi.org/10.1016/j.wear.2011.08.013S949927

Molecular hierarchical release using hydrogenated graphene origami under electric field

In recent years, drug delivery has progressively become one of the main research areas in the field of biomedicine. However, the graded drug release remains a serious challenge at the nano-scales. Herein, we successfully simulated the graded release of C60 and C180 from the graphene box inspired by the origami technique under the control of an external electric field via molecular dynamics (MD) simulations. Our results provide a feasible scheme for hierarchical drug delivery at the nano-scales. The graphene origami was generated through the folding of graphene guided by its creases which were created by combining carbon atoms with hydrogen atoms and transforming sp2 to sp3 bonds at the combination line. We can construct complex graphene origami by designing reasonable hydrogen atoms distribution on graphene. This provides a simple and practicable program for designing complex graphene-based nanodevices for drug delivery