Graphene is a rapidly rising star on the horizon of materials science and condensed-matter physics. This strictly two-dimensional material exhibits exceptionally high crystal and electronic quality, and, despite its short history, has already revealed a cornucopia of new physics and potential applications, which are briefly discussed here. Whereas one can be certain of the realness of applications only when commercial products appear, graphene no longer requires any further proof of its importance in terms of fundamental physics. Owing to its unusual electronic spectrum, graphene has led to the emergence of a new paradigm of 'relativistic' condensed-matter physics, where quantum relativistic phenomena, some of which are unobservable in high-energy physics, can now be mimicked and tested in table-top experiments. More generally, graphene represents a conceptually new class of materials that are only one atom thick, and, on this basis, offers new inroads into low-dimensional physics that has never ceased to surprise and continues to provide a fertile ground for applications.

The rise of graphene

Three parallel algorithms for classical molecular dynamics are presented. The first assigns each processor a fixed subset of atoms; the second assigns each a fixed subset of inter-atomic forces to compute; the third assigns each a fixed spatial region. The algorithms are suitable for molecular dynamics models which can be difficult to parallelize efficiently—those with short-range forces where the neighbors of each atom change rapidly. They can be implemented on any distributed-memory parallel machine which allows for message-passing of data between independently executing processors. The algorithms are tested on a standard Lennard-Jones benchmark problem for system sizes ranging from 500 to 100,000,000 atoms on several parallel supercomputers--the nCUBE 2, Intel iPSC/860 and Paragon, and Cray T3D. Comparing the results to the fastest reported vectorized Cray Y-MP and C90 algorithm shows that the current generation of parallel machines is competitive with conventional vector supercomputers even for small problems. For large problems, the spatial algorithm achieves parallel efficiencies of 90% and a 1840-node Intel Paragon performs up to 165 faster than a single Cray C9O processor. Trade-offs between the three algorithms and guidelines for adapting them to more complex molecular dynamics simulations are also discussed.

Fast parallel algorithms for short-range molecular dynamics

다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

We measured the elastic properties and intrinsic breaking strength of free-standing monolayer graphene membranes by nanoindentation in an atomic force microscope. The force-displacement behavior is interpreted within a framework of nonlinear elastic stress-strain response, and yields second- and third-order elastic stiffnesses of 340 newtons per meter (N m(-1)) and -690 Nm(-1), respectively. The breaking strength is 42 N m(-1) and represents the intrinsic strength of a defect-free sheet. These quantities correspond to a Young's modulus of E = 1.0 terapascals, third-order elastic stiffness of D = -2.0 terapascals, and intrinsic strength of sigma(int) = 130 gigapascals for bulk graphite. These experiments establish graphene as the strongest material ever measured, and show that atomically perfect nanoscale materials can be mechanically tested to deformations well beyond the linear regime.

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Measurement of the Elastic Properties and Intrinsic Strength of Monolayer Graphene

Carbon Nanostructures: Covalently Connected Carbon Nanostructures for Current Collectors in Both the Cathode and Anode of Li–S Batteries (Adv. Mater. 41/2016)

The use of single-crystal substrates as templates for the epitaxial growth of single-crystal overlayers has been a primary principle of materials epitaxy for more than 70 years. Here we report our finding that, though counterintuitive, single-crystal 2D materials can be epitaxially grown on twinned crystals. By establishing a geometric principle to describe 2D materials alignment on high-index surfaces, we show that 2D material islands grown on the two sides of a twin boundary can be well aligned. To validate this prediction, wafer-scale Cu foils with abundant twin boundaries were synthesized, and on the surfaces of these polycrystalline Cu foils, we have successfully grown wafer-scale single-crystal graphene and hexagonal boron nitride films. In addition, to greatly increasing the availability of large area high-quality 2D single crystals, our discovery also extends the fundamental understanding of materials epitaxy. 

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Single-crystal two-dimensional material epitaxy on tailored non-single-crystal substrates

Long bundles of defect-free carbon nanotubes can exhibit exceptionally high strength.

Strong bundles based on carbon nanotubes

Graphene has demonstrated broad applications due to its prominent properties. Its molecular structure makes graphene achiral. Here, we propose a direct way to prepare chiral graphene by transferring chiral structural conformation from chiral conjugated amino acids onto graphene basal plane through Π-Π interaction followed by thermal fusion. Using atomic resolution transmission electron microscopy, we estimated an areal coverage of the molecular imprints (chiral regions) up to 64% on the basal plane of graphene (grown by chemical vapor deposition). The high concentration of molecular imprints in their single layer points to a close packing of the deposited amino acid molecules prior to "thermal fusion". Such "molecular chirality-encoded graphene" was tested as an electrode in electrochemical enantioselective recognition. The chirality-encoded graphene might find use for other chirality-related studies and the encoding procedure might be extended to other two-dimensional materials.

Encoding Enantiomeric Molecular Chiralities on Graphene Basal Planes.

Rotational spectra have been observed for eight isotopic species of the diborane–HCl complex with a Balle–Flygare, pulsed nozzle, Fourier transform microwave spectrometer. The dimer has a linear, or at most slightly bent B–B⋅⋅⋅H/DCl equilibrium structure with the H/D end of the HCl attracted symmetrically to a terminal BH2 group of the diborane. Three B2H6–HCl species homonuclear in the boron were observed to tunnel while those with 10B11BH6 or DCl did not. The tunneling splits each rotational transition into two components of comparable intensity, separated by several MHz depending on J and K. The a–dipole transitions are characteristic of a prolate, very near symmetric top; only K=0 and ±1 transitions were found. Rotational constants are reported for all species. The B, DJ, H, (B‐C), and DJK constants determined for 11B2H6–H35Cl are for the A1 tunneling state 1273.364(1) MHz, 5.56(5) kHz, 1.0(8) Hz, 5.3(2) MHz, and −2.1(3) MHz; for the A2 tunneling state 1273.856(1) MHz, 11.64(7) kHz, 33.1(9) Hz, 5.70(...

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Rodney S. Ruoff

Papers

Carbon Nanostructures: Covalently Connected Carbon Nanostructures for Current Collectors in Both the Cathode and Anode of Li–S Batteries (Adv. Mater. 41/2016)

Single-crystal two-dimensional material epitaxy on tailored non-single-crystal substrates

Strong bundles based on carbon nanotubes

Encoding Enantiomeric Molecular Chiralities on Graphene Basal Planes.

Tunneling in a linear B2H6–HCl dimer