Rodney S. Ruoff

Bio: Rodney S. Ruoff is an academic researcher from Ulsan National Institute of Science and Technology. The author has contributed to research in topics: Graphene & Graphene oxide paper. The author has an hindex of 164, co-authored 666 publications receiving 194902 citations. Previous affiliations of Rodney S. Ruoff include Texas State University & North Carolina State University.

Large‐Area Uniform 1‐nm‐Level Amorphous Carbon Layers from 3D Conformal Polymer Brushes. A “Next‐Generation” Cu Diffusion Barrier?

Abstract: A reliable method for preparing a conformal amorphous carbon (a‐C) layer with a thickness of 1‐nm‐level, is tested as a possible Cu diffusion barrier layer for next‐generation ultrahigh‐density semiconductor device miniaturization. A polystyrene brush of uniform thickness is grafted onto 4‐inch SiO2/Si wafer substrates with “self‐limiting” chemistry favoring such a uniform layer. UV crosslinking and subsequent carbonization transforms this polymer film into an ultrathin a‐C layer without pinholes or hillocks. The uniform coating of nonplanar regions or surfaces is also possible. The Cu diffusion “blocking ability” is evaluated by time‐dependent dielectric breakdown (TDDB) tests using a metal−oxide−semiconductor (MOS) capacitor structure. A 0.82 nm‐thick a‐C barrier gives TDDB lifetimes 3.3× longer than that obtained using the conventional 1.0 nm‐thick TaNx diffusion barrier. In addition, this exceptionally uniform ultrathin polymer and a‐C film layers hold promise for selective ion permeable membranes, electrically and thermally insulating films in electronics, slits of angstrom‐scale thickness, and, when appropriately functionalized, as a robust ultrathin coating with many other potential applications.

Scanning tunneling microscopy and spectroscopy of carbon nanotubes

Abstract: Scanning tunneling microscopy (STM) and spectroscopy have been used to obtain images and current-voltage (I–V) curves of carbon nanotubes. The nanotubes are 5–7 nm in diameter and up to 1 in length. The I–V curves indicate that carbon nanotubes with diameters of approximately 5.0 nm are metallic. This observation is consistent with recent theoretical predictions concerning the electronic structure of carbon nanotubes in relation to their diameter and helicity. Using STM, we also observe graphene sheets in the carbon soot that is produced during the arc discharge. The STM images of nanotubes are in good agreement with transmission electron microscopy images. Potential applications of carbon nanotubes include novel nanometer-size electronic devices and fiber-reinforced materials.

(NH4)3C60: A New C60 Superconductor?

Abstract: The enthalpy of formation (ΔHf) of the ionic solid (NH4+)3C603- is assessed. The solid is found to be stable with respect to the standard state reactants (N2(g), H2(g), and C60(s)), with a ΔHf of −1.82 eV/mol. For comparison, this enthalpy of formation is less than the enthalpy of formation of, e.g., K3C60 (−6.27 eV/mol). There are several attractive features of (NH4+)3C603- as a new ionic solid and potential superconductor, if it can be synthesized. It is well-known that the size of the NH4+ cation is almost exactly the same as that of Rb+. Among the M3C60 superconductors, Rb3C60 has the second highest superconducting transition temperature, with Tc = 28 K, which suggests that the Tc of a superconducting (NH4)3C60 could be higher than yet achieved for C60 superconductors, of which Cs3C60(s) has the highest Tc of 40 K. There is a 28% relative mass change when the NH4+ countercation is replaced by 15ND4+, which is a much larger relative change than can be achieved with the alkali metal atoms, which is impo...

The Energy Return on Investment for Algal Biocrude: Results for a Research Production Facility

Abstract: This study is an experimental determination of the energy return on investment (EROI) for algal biocrude production at a research facility at the University of Texas at Austin (UT). During the period of this assessment, algae were grown at several cultivation scales and processed using centrifugation for harvesting, electromechanical cell lysing, and lipid separation in an enhanced coalescence membrane. The separated algal lipids represent a biocrude product that could be refined into fuel. To determine the EROI, a second order analysis was conducted, which includes direct and indirect energy flows, but does not consider capital energy expenses. At the time that the data in this study was collected, the research program was focused on improving biomass and lipid productivity. As a result, some higher efficiency processing steps were replaced by lower efficiency ones to permit other experiments. Although the production process evaluated here was energy negative, the majority of the energy consumption resulted from non-optimized growth conditions. Therefore, the experimental results do not represent an expected typical case EROI for algal fuels, but rather outline the important parameters to consider in such an analysis. The results are the first known experimental energy balance for an integrated algal biocrude production facility. A Reduced Case is presented that speculates the energy use for a similar system in commercial-scale production. In addition, an analytical model that is populated with data that have been reported in the literature is presented. For the experiments, the Reduced Case, and Literature Model, the estimated EROI was 1.3 × 10−3 , 0.13, and 0.57, respectively (refining energy requirements are not included in the experimental or Reduced Case EROI value). These results were dominated by growth inputs (96.59%, 94.15%, and 76.32% of the total energy requirement, respectively). For the experiments and Literature Model, lipid separation was the most energy intensive processing step (2.47% and 10.06%, respectively), followed by harvesting, refining, and then electromechanical cell lysing.Copyright © 2010 by ASME

The rise of graphene

Abstract: 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.

Fast parallel algorithms for short-range molecular dynamics

Abstract: 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.

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

Abstract: 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。

Measurement of the Elastic Properties and Intrinsic Strength of Monolayer Graphene

Abstract: 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.