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.

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Nanostructures in Biodiagnostics

We demonstrate here rapid, efficient and reliable fabrication and replication of high density arrays of polymeric structures using ultrathin layer-mediated processes. Highly uniform polymeric structures with submicrometer to nanometer radius-of-curvatures and consistent vertical profiles could be achieved via sequential replication cycles. Highly controllable dry surface treatment has been used to create a chemically inert and stable interfacial zone between two polymers of the same chemical identities to allow simple replica molding and rapid intact release of highly flexible molded polymeric structures. The approach could, in principle, be extended to other systems with appropriate modification of interfacial surface properties.

High Density Array Matrices of Polymeric Structures by Ultrathin Interfacial Layer-Mediated Double Replication Approach

Future miniaturized devices, beyond the Moore's law era of silicon, are expected to rely on new, ingenious methods to implement spatially controlled and highly functional nanoscale components synthesized by inexpensive chemistry. Chip technology based on self-assembly would enhance performance and packing density by orders of magnitude, deliver rich on-chip functionality, and operate at molecular level. Low-dimensional semiconductor nanostructues and organic molecules, which offer unique possibilities such as extremely low power dissipation, quantum effects, surface sensitivity and low synthesis cost, could be the building blocks for next-generation electronics. In this paper we discuss the potential successors of the silicon CMOS technology at the end of the ITRS Roadmap (in ∼15 years). The disruptive technologies, rooted in nanoscale science, would aid in the continued advancement of integrated circuit technology - not necessarily through straightforward transistor geometry scaling - in several mainstream applications such as computing and data storage.

Nanotechnology : Role in emerging nanoelectronics

The continual scaling down of semiconductors to 100 nm and below necessitates a characterization technique to resolve high aspect ratio features in the nanoscale regime. This paper reports the use of atomic force microscope coupled with high aspect ratio multi-walled carbon nanotube scanning probe tip for the purpose of imaging surface profile of photoresists. Multi-walled carbon nanotube tips used in this work are 5-10 nm in diameter and about a micron long. Their exceptional mechanical strength and ability to reversibly buckle enable to resolve steep, deep nanometer-scale features. Images of photoresist patterns generated by 257 nm interference lithography as well as 193 nm lithography are presented to demonstrate multi-walled carbon nanotube scanning probe tip for applications in metrology.

Carbon nanotube scanning probe for surface profiling of DUV and 193-nm photoresist pattern

The development of display scan drivers is an essential step in the effort to develop transparent and flexible display devices based on nanowire transistors. Here we report a transparent nanowire-based shift register that functions as the standard logic circuit of a display scan driver. To form the shift register circuits using only n-type nanowire transistors, a novel circuit structure was introduced to avoid the output voltage drop typical of purely n-type circuits. A circuit simulation based on the measured nanowire transistor characteristics was developed in the planning phase to verify the circuit operation of the shift register. The shift register successfully produced an output of 0–3 V without an output voltage drop while applying an input of 3 V peak to peak. In addition, the shift register was designed to have multiple channels with a randomly oriented nanowire placement method to enhance the operation yield.

A nanowire-based shift register for display scan drivers

Terrestrial radiation is ubiquitous. Alpha particle radioactive contamination is often found in semiconductor packaging materials, and neutrons generated by cosmic rays constantly approach the ground. Historically, these radiations are regarded as a source of soft-error. We are in the era of aggressive device miniaturization, operation voltage scaling and increasing frequency. Herein, we present that the terrestrial radiation-induced single event can potentially result in hard-error. As a result, radiation hard-error hardening might be necessary in the near future even in consumer electronics.

Meyya Meyyappan

Papers

High Density Array Matrices of Polymeric Structures by Ultrathin Interfacial Layer-Mediated Double Replication Approach

Nanotechnology : Role in emerging nanoelectronics

Carbon nanotube scanning probe for surface profiling of DUV and 193-nm photoresist pattern

A nanowire-based shift register for display scan drivers

Single Event Hard Error due to Terrestrial Radiation