There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

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

[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

In the last 10 years the field of molecular diagnostics has witnessed an explosion of interest in the use of nanomaterials in assays for gases, metal ions, and DNA and protein markers for many diseases. Intense research has been fueled by the need for practical, robust, and highly sensitive and selective detection agents that can address the deficiencies of conventional technologies. Chemists are playing an important role in designing and fabricating new materials for application in diagnostic assays. In certain cases assays based upon nanomaterials have offered significant advantages over conventional diagnostic systems with regard to assay sensitivity, selectivity, and practicality. Some of these new methods have recently been reviewed elsewhere with a focus on the materials themselves or as subclassifications in more generalized overviews of biological applications of nanomaterials.1-7 We intend to review some of the major advances and milestones in the field of detection systems based upon nanomaterials and their roles in biodiagnostic screening for nucleic acids, * To whom correspondence should be addressed. Phone: 847-4913907. Fax: 847-467-5123. E-mail: chadnano@northwestern.edu. Nathaniel L. Rosi earned his B.A. degree at Grinnell College (1999) and his Ph.D. degree from the University of Michigan (2003), where he studied the design, synthesis, and gas storage applications of metal−organic frameworks under the guidance of Professor Omar M. Yaghi. In 2003 he began postdoctoral studies as a member of Professor Mirkin’s group at Northwestern University. His current research focuses on the rational assembly of DNA-modified nanostructures into larger-scale materials.

/pdf/nanostructures-in-biodiagnostics-5553cs9yqw.pdf

Nanostructures in Biodiagnostics

A gas sensor, fabricated by the simple casting of single-walled carbon nanotubes (SWNTs) on an interdigitated electrode (IDE), is presented for gas and organic vapor detection at room temperature. The sensor responses are linear for concentrations of sub ppm to hundreds of ppm with detection limits of 44 ppb for NO2 and 262 ppb for nitrotoluene. The time is on the order of seconds for the detection response and minutes for the recovery. The variation of the sensitivity is less than 6% for all of the tested devices, comparable with commercial metal oxide or polymer microfilm sensors while retaining the room-temperature high sensitivity of the SWNT transistor sensors and manufacturability of the commercial sensors. The extended detection capability from gas to organic vapors is attributed to direct charge transfer on individual semiconducting SWNT conductivity with additional electron hopping effects on intertube conductivity through physically adsorbed molecules between SWNTs.

/pdf/carbon-nanotube-sensors-for-gas-and-organic-vapor-detection-ip2iitcwf8.pdf

Carbon Nanotube Sensors for Gas and Organic Vapor Detection

Carbon nanotubes (CNTs), due to their unique electronic and extraordinary mechanical properties, have been receiving much attention for a wide variety of applications. Recently, plasma enhanced chemical vapour deposition (PECVD) has emerged as a key growth technique to produce vertically-aligned nanotubes. This paper reviews various plasma sources currently used in CNT growth, catalyst preparation and growth results. Since the technology is in its early stages, there is a general lack of understanding of growth mechanisms, the role of the plasma itself, and the identity of key species responsible for growth. This review is aimed at the low temperature plasma research community that has successfully addressed such issues, through plasma and surface diagnostics and modelling, in semiconductor processing and diamond thin film growth.

https://iopscience.iop.org/article/10.1088/0963-0252/12/2/312/pdf

Carbon nanotube growth by PECVD: a review

STRUCTURES AND PROPERTIES OF CARBON NANOTUBES, Jie Han Bonding of Carbon Atoms Defect-Free Nanotube Defective Nanotubes Electrical Properties Optical and Optoelectronic Properties Mechanical and Electromechanical Properties Magnetic and Electromagnetic Properties Chemical and Electrochemical Properties Thermal and Thermoelectric Properties COMPUTATIONAL NANOTECHNOLOGY OF CARBON NANOTUBES, Deepak Srivastava Multiscale Simulation Techniques for Computational Nanotechnology Structure and Symmetry Nanomechanics and Thermal Properties Chemical Functionalization, Physisorption, and Diffusion in Carbon Nanotubes Nanoelectronics and Sensors Summary and Outlook GROWTH OF CARBON NANOTUBES BY ARC DISCHARGE AND LASER ABLATION, Alexander P. Moravsky, Eugene M. Wexler, and Raouf O. Loutfy Arc Discharge Production of MWNTs MWNT Production by Laser Ablation of Graphite Arc Discharge Production of SWNTs Arc Discharge Production of DWNTs SWNT Production by Laser Ablation of Carbon-Metal Target Conclusions GROWTH: CVD AND PECVD, M. Meyyappan Growth Apparatus Catalyst Preparation Growth Results Growth Mechanisms Modeling and Diagnostics Challenges and Future Directions CHARACTERIZATION TECHNIQUES IN CARBON NANOTUBE RESEARCH, K. McGuire and A.M. Rao Electron Microscopy Atomic Force and Scanning Tunneling Microscopy Properties Characterization Electrical Conductivity Measurements Thermoelectric Measurements Raman Spectroscopy X-Ray Diffraction Summary APPLICATIONS IN SCANNING PROBE MICROSCOPY, Cattien V. Nguyen Development of the Atomic Force Microscope and the Role of the Scanning Probe Mechanical Properties of Carbon Nanotubes in the Context of SPM Applications Fabrication of Carbon Nanotube Scanning Probes Applications of Carbon Nanotube Probes Summary NANOELECTRONICS APPLICATIONS, Toshishige Yamada Carrier Characterization Doping Methods SWNT FETs Intermolecular Metal-Semiconductor SWNT Heterojunctions SWNT pn Junction as Esaki Diode Single-Electron Tunneling Devices Using SWNTs Other Semiconducting SWNT Devices Transport in Metallic SWNTs General Remarks on NanoFETs FIELD EMISSION, Philippe Sarrazin Structure and Microstructure of CNT Emitters Applications of CNT Emitters Conclusions CARBON NANOTUBE APPLICATIONS: CHEMICAL AND PHYSICAL SENSORS, Jing Li Carbon Nanotube Chemical Sensors Carbon Nanotube Physical Sensors and Actuators Summary and Outlook APPLICATIONS: BIOSENSORS, Jun Li Fabrication of Carbon Nanotube Biosensors Biosensing Applications Summary and Future Directions APPLICATIONS: COMPOSITES, E.V. Barrera, M.L. Shofner, and E.L. Corral Nanotube Superiority Polymer Nanocomposites Nanotube-Metal Composites Ceramic Matrix Composites Summary and Outlook OTHER APPLICATIONS, M. Meyyappan Applications in Integrated Circuit Manufacturing Catalyst Support and Absorbents Storage/Intercalation of Metals Membranes and Separation

Carbon Nanotubes: Science and Applications

Harnessing the potential of single crystal inorganic nanowires for practical advanced nanoscale applications requires not only reproducible synthesis of highly regular one-dimensional (1D) nanowire arrays directly on device platforms but also elegant device integration which retains structural integrity of the nanowires while significantly reducing or eliminating complex critical processing steps. Here we demonstrate a unique, direct, and bottom-up integration of a semiconductor 1D nanowire, using zinc oxide (ZnO) as an example, to obtain a vertical surround-gate field-effect transistor (VSG-FET). The vertical device structure and bottom-up integration reduce process complexity, compared to conventional top-down approaches. More significantly, scaling of the vertical channel length is lithographically independent and decoupled from the device packing density. A bottom electrical contact to the nanowire is uniquely provided by a heavily doped underlying lattice-match substrate. Based on the nanowire-integrated platform, both n- and p-channel VSG-FETs are fabricated. The vertical device architecture has the potential for use in tera-level ultrahigh-density nanoscale memory and logic devices.

Single Crystal Nanowire Vertical Surround-Gate Field-Effect Transistor

A nanoelectrode array based on vertically aligned multiwalled carbon nanotubes (MWNTs) embedded in SiO2 is used for ultrasensitive DNA detection. Characteristic electrochemical behaviors are observed for measuring bulk and surface-immobilized redox species. Sensitivity is dramatically improved by lowering the nanotube density. Oligonucleotide probes are selectively functionalized to the open ends of nanotubes. The hybridization of subattomole DNA targets can be detected by combining such electrodes with Ru(bpy)32+ mediated guanine oxidation.

Meyya Meyyappan

Papers

Carbon Nanotube Sensors for Gas and Organic Vapor Detection

Carbon nanotube growth by PECVD: a review

Carbon Nanotubes: Science and Applications

Single Crystal Nanowire Vertical Surround-Gate Field-Effect Transistor

Carbon Nanotube Nanoelectrode Array for Ultrasensitive DNA Detection