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Here, we report on the in vitro binding properties of the known pyridine dicarboxamide G-quadruplex ligand 360A and a new dimeric analogue (360A)2A to human telomeric DNA higher-order G-quadruplex (G4) structures. This study points to original binding features never reported for G4 ligands, and reveals a greater efficiency for the dimeric ligand to displace RPA (a ssDNA binding protein involved in telomere replication) from telomeric DNA. [ABSTRACT FROM AUTHOR]

Thin foils are used extensively in space plasma spectrometers, for example, for generation of a coincidence measurement via secondary electron emission in time-of-flight mass spectrometers and charge conversion of energetic neutral atoms (ENAs) in ENA imagers. An ion or neutral atom passing through the carbon foil experiences energy loss and straggling that can degrade the energy resolution or mass resolution. These effects need to be quantified in order to permit efficient instrument development and modeling. We present measurements of energy loss and energy loss straggling for H, He, C, N, O, Ne, and Ar ions between 1 and 50 keV passing through carbon foils of different thicknesses (nominally between 0.5 and 3.0 μg/cm2). We derive empirical relationships for the energy loss and energy loss straggling as a function of foil thickness, ion species, and ion energy. In particular, below ∼10 keV the energy loss of hydrogen seems to vary with foil thickness and the energy loss straggling seems to vary with the square root of the thickness. Our results apply equally well to ions and neutral atoms. [ABSTRACT FROM AUTHOR]

We have developed a compact partially ferromagnetic electromagnet to produce an Ioffe-Pritchard trap for neutral atoms. Our structure permits strong magnetic confinement with low power consumption. Compared to the previous iron-core electromagnet [B. Desruelle, V. Boyer, P. Bouyer, G. Birkl, M. Lécrivain, F. Alves, C. Westbrook, and A. Aspect, Eur. Phys. J. D 1, 255 (1998)], it allows for easy compensation of remnant fields and very high stability, along with cost-effective realization and compactness. We describe and characterize our apparatus and demonstrate trapping and cooling of 87Rb atoms to quantum degeneracy. Pure Bose-Einstein condensates containing 106 atoms are routinely realized on a half-minute cycle. In addition we test the stability of the magnetic trap by producing atom lasers. [ABSTRACT FROM AUTHOR]