54 research outputs found
Self-Doping of Gold Chains on Silicon: A New Structural Model for Si(111)5x2-Au
A new structural model for the Si(111)5x2-Au reconstruction is proposed and
analyzed using first-principles calculations. The basic model consists of a
"double honeycomb chain" decorated by Si adatoms. The 5x1 periodicity of the
honeycomb chains is doubled by the presence of a half-occupied row of Si atoms
that partially rebonds the chains. Additional adatoms supply electrons that
dope the parent band structure and stabilize the period doubling; the optimal
doping corresponds to one adatom per four 5x2 cells, in agreement with
experiment. All the main features observed in scanning tunneling microscopy and
photoemission are well reproduced.Comment: 4 pages, 4 figures, to appear in Phys. Rev. Lett. (preprint with high
quality figures available at
http://cst-www.nrl.navy.mil/~erwin/papers/ausi111
Solution of Ge(111)-(4Ă—4)-Ag structure using direct methods applied to X-ray diffraction data
H19 Antisense RNA Can Up-Regulate Igf2 Transcription by Activation of a Novel Promoter in Mouse Myoblasts
It was recently shown that a long non-coding RNA (lncRNA), that we named the 91H RNA (i.e. antisense H19 transcript), is overexpressed in human breast tumours and contributes in trans to the expression of the Insulin-like Growth Factor 2 (IGF2) gene on the paternal chromosome. Our preliminary experiments suggested that an H19 antisense transcript having a similar function may also be conserved in the mouse. In the present work, we further characterise the mouse 91H RNA and, using a genetic complementation approach in H19 KO myoblast cells, we show that ectopic expression of the mouse 91H RNA can up-regulate Igf2 expression in trans despite almost complete unmethylation of the Imprinting-Control Region (ICR). We then demonstrate that this activation occurs at the transcriptional level by activation of a previously unknown Igf2 promoter which displays, in mouse tissues, a preferential mesodermic expression (Pm promoter). Finally, our experiments indicate that a large excess of the H19 transcript can counteract 91H-mediated Igf2 activation. Our work contributes, in conjunction with other recent findings, to open new horizons to our understanding of Igf2 gene regulation and functions of the 91H/H19 RNAs in normal and pathological conditions
Strong Carrier Lifetime Enhancement in GaAs Nanowires Coated with Semiconducting Polymer
ADSORPTION SITES AND RELATIVE STABILITIES OF THE 3X1 AND SQUARE-ROOT-3 PHASES OF AG ON SI(111)
Detecting and localizing surface dynamics with STM: a study of the Sn/Ge(111) and Sn/Si(111) alpha-phase surfaces
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