Unexpected Structures for Intercalation of Sodium in Epitaxial Graphene-SiC Interfaces

We show using scanning tunneling microscopy, spectroscopy, and ab initio calculations that several intercalation structures exist for Na in epitaxial graphene on SiC(0001). Intercalation takes place at room temperature and Na electron-dopes the graphene. It intercalates in-between single-layer graphene and the carbon-rich interfacial layer. It also penetrates beneath the interfacial layer and decouples it to form a second graphene layer. This decoupling is accelerated by annealing and is verified by direct Na deposition onto the interface layer. Our observations show that intercalation in graphene is fundamentally different than in graphite and is a versatile means of electronic control.Comment: 10 pages text, 2 pages, references, and 4 figure page

Observing The Mediterranean Sea from space: 21 years of Pathfinder-AVHRR Sea Surface Temperatures (1985 to 2005). Re-analysis and validation

International audienceThe time series of satellite infrared AVHRR data from 1985 to 2005 has been used to produce a daily series of optimally interpolated SST maps over the regular grid of the operational MFSTEP OGCM model of the Mediterranean basin. A complete validation of this OISST (Optimally Interpolated Sea Surface Temperature) product with in situ measurements has been performed in order to exclude any possibility of spurious trends due to instrumental calibration errors/shifts or algorithms malfunctioning related to local geophysical factors. The validation showed that satellite OISST is able to reproduce in situ measurements with a mean bias of less than 0.1°C and RMSE of about 0.5°C and that errors do not drift with time or with the percent interpolation error

Metabolic Regulation of Neocortical Expansion in Development and Evolution

The neocortex, the seat of our higher cognitive abilities, has expanded in size during the evolution of certain mammals such as primates, including humans. This expansion occurs during development and is linked to the proliferative capacity of neural stem and progenitor cells (NPCs) in the neocortex. A number of cellintrinsic and cell-extrinsic factors have been implicated in increasing NPC proliferative capacity. However, NPC metabolism has only recently emerged as major regulator of NPC proliferation. In this Perspective, we summarize recent insights into the role of NPC metabolism in neocortical development and neurodevelopmental disorders and its relevance for neocortex evolution. We discuss certain human-specific genes and microcephaly-implicated genes that operate in, or at, the mitochondria of NPCs and stimulate their proliferation by promoting glutaminolysis. We also discuss other metabolic pathways and develop a perspective on how metabolism mechanistically regulates NPC proliferation in neocortical development and how this contributed to neocortex evolution.Peer reviewe

N-(4-Methyl­phen­yl)-N′-phenyl­butane­diamide monohydrate

In the title hydrate, C17H18N2O2·H2O, the dihedral angles formed by the aromatic rings of the benzene and methyl­benzene groups with the mean planes of the attached NH—C(O)—CH2 fragments are 12.6 (4) and 23.3 (3)°, respectively, while that between the two aromatic rings is 73.7 (2)°. In the crystal, the water mol­ecule accepts two and makes two hydrogen bonds. The mol­ecules are packed into layers parallel to (101) by O—H⋯O and N—H⋯O hydrogen-bonding inter­actions

N-(2-Chloro­phen­yl)-N′-(2-methyl­phen­yl)succinamide

In the title compound, C17H17ClN2O2, the asymmetric unit contains half a mol­ecule with a centre of symmetry at the mid-point of the central C—C bond. The conformations of the amide O atoms are anti to the methyl­ene atoms. Further, the N—H bonds in the amide fragments are anti to the ortho-chloro/methyl groups in the adjacent benzene rings. The dihedral angle between the benzene ring and the NH—C(O)—CH2 segment in the two halves of the mol­ecule is 62.0 (2)°. In the crystal, a series of N—H⋯O inter­molecular hydrogen bonds link the mol­ecules into column-like infinite chains along the a axis. The methyl and Cl groups are disordered with respect to the ortho positions of the benzene ring, with site-occupation factors of 0.5 each

Towards high resolution mapping of 3-D mesoscale dynamics from observations

The MyOcean R&D project MESCLA (MEsoSCaLe dynamical Analysis through combined model, satellite and in situ data) was devoted to the high resolution 3-D retrieval of tracer and velocity fields in the oceans, based on the combination of in situ and satellite observations and quasi-geostrophic dynamical models. The retrieval techniques were also tested and compared with the output of a primitive equation model, with particular attention to the accuracy of the vertical velocity field as estimated through the <b><i>Q</i></b> vector formulation of the omega equation. The project focused on a test case, covering the region where the Gulf Stream separates from the US East Coast. This work demonstrated that innovative methods for the high resolution mapping of 3-D mesoscale dynamics from observations can be used to build the next generations of operational observation-based products

Mn Interstitial Diffusion in (Ga,Mn)As

We present a combined theoretical and experimental study of the ferromagnetic semiconductor (Ga,Mn)As which explains the remarkably large changes observed on low temperature annealing. Careful control of the annealing conditions allows us to obtain samples with ferromagnetic transition temperatures up to 159 K. Ab initio calculations, and resistivity measurements during annealing, show that the observed changes are due to out-diffusion of Mn interstitials towards the surface, governed by an energy barrier of about 0.7-0.8 eV. The Mn interstitial is a double donor resulting in compensation of charge carriers and suppression of ferromagnetism. Electric fields induced by high concentrations of substitutional Mn acceptors have a significant effect on the diffusion.Comment: 5 pages, 4 figures, submitted to Physical Review Letter