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

Advancing perovskite solar cell technologies toward their theoretical power conversion efficiency (PCE) requires delicate control over the carrier dynamics throughout the entire device. By controlling the formation of the perovskite layer and careful choices of other materials, we suppressed carrier recombination in the absorber, facilitated carrier injection into the carrier transport layers, and maintained good carrier extraction at the electrodes. When measured via reverse bias scan, cell PCE is typically boosted to 16.6% on average, with the highest efficiency of ~19.3% in a planar geometry without antireflective coating. The fabrication of our perovskite solar cells was conducted in air and from solution at low temperatures, which should simplify manufacturing of large-area perovskite devices that are inexpensive and perform at high levels.

http://science.sciencemag.org/content/sci/345/6196/542.full.pdf

Interface engineering of highly efficient perovskite solar cells

A novel non-fullerene electron acceptor (ITIC) that overcomes some of the shortcomings of fullerene acceptors, for example, weak absorption in the visible spectral region and limited energy-level variability, is designed and synthesized. Fullerene-free polymer solar cells (PSCs) based on the ITIC acceptor are demonstrated to exhibit power conversion effi ciencies of up to 6.8%, a record for fullerene-free PSCs.

An electron acceptor challenging fullerenes for efficient polymer solar cells.

Mechanical Behavior of Carbon Nanotube Forests Grown With Plasma Enhanced Chemical Vapor Deposition: Pristine and Conformally Coated

For many flexible electronic and photonic devices, roll-to-roll processing technology has been a novel driving force for their development. This processing technology can also be applied to solar photovoltaic (PV) module packaging. However, to fit its processing needs, there are several challenges. This paper presents surface modification of PET carrier film using UV/Ozone treatment to improve adhesion with the adhesive material. Whereas previous studies also utilized treatment methods to increase the wettability characteristics, in this paper we present the results of a relatively weaker irradiation technique, UV/Ozone treatment at room temperature condition. We found that this treatment method increases the wettability or surface energy by up to 1.4-fold and demonstrates a 28.3% increase in average adhesion strength.

Design and Surface Modification of PET Substrates Using UV/Ozone Treatment for Roll-to-Roll Processed Solar Photovoltaic (PV) Module Packaging

Synthesis of sesquiterpene antitumor lactones. 9. The hydronaphthalene route to pseudoguaianes. Total synthesis of (.+-.)-confertin

Polycrystalline silicon has been a primary material used in development of mocroelectrical mechanical systems due to its attractive structural properties and compatibility with CMOS processing. Among its many applications, polysilicon is currently being employed in MEMS devices that require thermal dissipation or thermal management to ensure functionality (thermal actuators, microengines, etc.). In these applications, heat conduction in polycrystalline silicon becomes a primary factor in the design, performance, and reliability of thermal MEMS.© 2003 ASME

The Effects of Processing Conditions on the Thermal Conductivity of Polycrystalline Silicon Films

Methods used to measure the temperature of Al x Ga 1―x N based ultraviolet light emitting diodes (UV LEDs) are based on optical or electrical phenomena that are sensitive to either local, surface, or average temperatures within the LED. A comparative study of the temperature rise of Al x Ga 1―x N UV LEDs measured by micro-Raman spectroscopy, infrared (IR) thermography, and the forward voltage method is presented. Experimental temperature measurements are provided for UV LEDs with micropixel and interdigitated contact geometries, as well as for a number of different packaging configurations. It was found that IR spectroscopy was sensitive to optical properties of the device layers, while forward voltage method provided higher temperatures, in general. Raman spectroscopy was used to measure specific layers within the LED, showing that growth substrate temperatures in the flip-chip LEDs agreed more closely to IR measurements while layers closer to the multiple quantum wells (MQWs) agreed more closely with Forward Voltage measurements.

Samuel Graham

Papers

Mechanical Behavior of Carbon Nanotube Forests Grown With Plasma Enhanced Chemical Vapor Deposition: Pristine and Conformally Coated

Design and Surface Modification of PET Substrates Using UV/Ozone Treatment for Roll-to-Roll Processed Solar Photovoltaic (PV) Module Packaging

Synthesis of sesquiterpene antitumor lactones. 9. The hydronaphthalene route to pseudoguaianes. Total synthesis of (.+-.)-confertin

The Effects of Processing Conditions on the Thermal Conductivity of Polycrystalline Silicon Films

A Comparative Study of Thermal Metrology Techniques for Ultraviolet Light Emitting Diodes