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.

Optimization of Graphite Composite Latent Heat Storage Systems

Metalation of N-tert-butylthiophene-2-sulfonamide with n-butyllithium occurs competitively at the 3- and 5-position of the thiophene ring. Equilibration of the initial mixture of carbanions or metalation with lithium diisopropylamide allows selective formation of the N,5-dilithiothiophenesulfonamide 7. This dianion is useful for the preparation of a number of 5-substituted thiophene-2-sulfonamides

Preparation and Utility of Dianions from N-tert-Butylthiophene-2-sulfonamide.

This paper describes the Engineers Without Borders-USA program to educate and train internationally responsible engineers and engineeri ng students. EWB-USA partners with underdeveloped and developing communities to improve their quality of life by implementing sustainable engineering projects using appropriate technology. EWB-USA continues to expand its role in the education community at the universi ty level and has started programs at the pre-college levels. These efforts stress humanitarian, service learning throu gh the application of real world projects, and allow stude nts to confront cultural as well as technological issues. Students have the opportunity to gain a different perspectiv e of their own culture and values through the lens of ot her cultures, and experience the positive and negative interaction between technological and social change .

/pdf/engineers-without-borders-usa-learning-through-humanitarian-1kgo9rnvdp.pdf

Engineers Without Borders - USA, Learning Through Humanitarian Service to Underdeveloped Communities

Probing local thermal conductivity variations in cvd diamond with large grains by time-domain thermoreflectance

PURPOSE: To provide a new polyether deriv. or its pharmaceutically acceptable salt which inhibits a protease coded by human immunodeficiency virus. CONSTITUTION: This compd. is expressed by formula I, and the inhibitor contains the compd. or its pharmaceutically acceptable salt. In formula I, A is H, R 1 -C(=O)-, (wherein R 1 is H, alkyl, aryl or 5- to 6-membered heterocyclic group), R 1 SO 2 , etc.; G is expressed by formula II; B is independent and is not present or expressed by formula, IV. In formula II, Z is O, S, NH; R a 9 , R b 9 are expressed by formula III (wherein (q) is 0 to 5; R 10 is H, OH, alkyl; R 11 is aryl, etc.); Q is -CH(OH)CH 2 -, -CH 2 NH-, etc.). In formula IV, R 20 is a hydrophobic group, J is YR 16 (wherein Y is O, NH; R 16 is H, alkyl, etc.). The compd. is., for example, N-[2-(R)-hydroxy-1(S)-indanyl]-5(S)-(1,1-dimethylethyloxycarbonylamino)-4(S)- hydroxy-2(R)-[4-(1,4,7-trioxaoctyl)phenyl]methyl-6-phenylhexaneamide. COPYRIGHT: (C)1992,JPO

Samuel Graham

Papers

Optimization of Graphite Composite Latent Heat Storage Systems

Preparation and Utility of Dianions from N-tert-Butylthiophene-2-sulfonamide.

Engineers Without Borders - USA, Learning Through Humanitarian Service to Underdeveloped Communities

Probing local thermal conductivity variations in cvd diamond with large grains by time-domain thermoreflectance

Hiv protease inhibitor having polyether substituent