ISSN:0031-9228    

DOI:10.1063/1.2180147

出版商:AIP    

年代:1906

数据来源: AIP

ISSN:0031-9228    

DOI:10.1063/1.2180151

出版商:AIP    

年代:1906

数据来源: AIP

ISSN:0031-9228    

DOI:10.1063/1.2180152

出版商:AIP    

年代:1906

数据来源: AIP

ISSN:0031-9228    

DOI:10.1063/1.2180160

出版商:AIP    

年代:1906

数据来源: AIP

ISSN:0031-9228    

DOI:10.1063/1.2180162

出版商:AIP    

年代:1906

数据来源: AIP

摘要:

Graphene, a single, one‐atom‐thick sheet of carbon atoms arranged in a honeycomb lattice, is the two‐dimensional building block for carbon materials of every other dimensionality. It can be stacked into 3D graphite, rolled into 1D nanotubes, or wrapped into 0D buckyballs. But for decades scientists presumed that a single 2D graphene sheet could not exist in its free state; they reasoned that its planar structure would be thermodynamically unstable and possibly curl into carbon soot. The University of Manchester's Andre Geim and colleagues there and at the Institute for Microelectronics Technology in Chernogolovka, Russia, put that presumption to rest a few months ago by isolating single graphene sheets.

ISSN:0031-9228    

DOI:10.1063/1.2180163

出版商:AIP    

年代:1906

数据来源: AIP

摘要:

Nature's simplest atom does not appear in the periodic table. Positronium (Ps), the short‐lived bound system of an electron and its antiparticle, the positron, was independently predicted by Arthur Ruark and John Wheeler after the positron was discovered in 1932. Four years before positronium itself was discovered in 1951, Egil Hylleraas and Aadne Ore had performed a variational calculation and concluded that Ps atoms could combine to form the diatomic moleculePs2.Two Ps atoms can also interact by swapping the spins of their two electrons or positrons.

ISSN:0031-9228    

DOI:10.1063/1.2180164

出版商:AIP    

年代:1906

数据来源: AIP

摘要:

DNA encodes the amino acid sequences of each protein in our bodies, but carries no instructions for how much of each protein to make. Instead, a cell's protein factories, its ribosomes, are set spinning by RNA, DNA's single‐stranded relative. By controlling when and which genes are transcribed from DNA to RNA, a cell regulates its protein production.

ISSN:0031-9228    

DOI:10.1063/1.2180165

出版商:AIP    

年代:1906

数据来源: AIP

摘要:

A little more than a year ago, in the wake of congressional approval of the fiscal year 2005 spending bill, US Office of Science director Raymond Orbach was upbeat. His office within the Department of Energy had received a 4.3&percent; increase in R&D money and Orbach was widely regarded as the big winner in a federal science budget that was mostly flat. The good times were short‐lived, however.

ISSN:0031-9228    

DOI:10.1063/1.2180166

出版商:AIP    

年代:1906

数据来源: AIP

摘要:

If the Gemini and Subaru observatories pull off a proposed joint Wide‐Field Multi‐Object Spectrograph (WFMOS), the collaboration would epitomize nascent trends in astronomy toward both time‐swapping and large “campaign” projects.

ISSN:0031-9228    

DOI:10.1063/1.2180167

出版商:AIP    

年代:1906

数据来源: AIP