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The refinement-tree partition for parallel solution of partial differential equations
No full textDynamic load balancing is considered in the context of adaptive multilevel methods for partial differential equations on distributed memory multiprocessors. An approach that periodically repartitions the grid is taken. The important properties of a partitioning algorithm are presented and discussed in this context. A partitioning algorithm based on the refinement tree of the adaptive grid is presented and analyzed in terms of these properties. Theoretical and numerical results are given
Acid-assisted consolidation of silver alloys for direct fillings
No full textSilver-rich metal powders cold-welded by consolidation have been investigated as possible direct dental filling material. The surface of the silver powder must undergo an acid treatment to remove existing contaminants and prevent formation of new surface contaminants during consolidation. This study was designed to investigate the effect of the acid treatment on the strength of the consolidated alloy, its reactivity with the surrounding tooth structure, and its reactions with certain cavity liners. This study investigated the effects of pH and concentration of fluoboric acid on the flexural strength of silver powder consolidated into rectangular beams in a partial 4 x 4 design. The study also assessed, by visible and scanning electron microscopy, what effect the acid-treated powders had on dentin that had been pre-coated with different cavity liners. Mean flexural strengths for beams consolidated using dental hand instruments were in the range (77.0 +/- 9.28) MPa to (166.1 +/- 17.6) MPa, where the quoted uncertainties are standard uncertainties (i.e., one standard deviation estimates). ANOVA indicated that fluoboric acid pH was highly significant (p <0.0001) with lower pH values resulting in higher flexural strength. Concentration alone was not a significant factor for flexural strengths, but there was a significant interaction between concentration and pH (p < 0.0001). Microscopy revealed that the acid-treated silver powder demineralized approximately 2 micro-m of dentin when used with no liner. The use of copal or polyamide varnishes eliminated most of this demineralization, but the use of a dentin adhesive liner resulted in some dislodgment and breakdown of the adhesive film by the acid. The results of this study indicate that this silver powder when treated with dilute fluoboric acid at a pH of approximately 1.0 can result in a filling material with strength equivalent to currently used conventional amalgam. The demineralization of tooth structure appears to be minimal and can be eliminated with the use of cavity liners
Richard Jackson
No full textRichard Jackson (January 7, 1998).
From the NIST photographer portrait photos collection
(Audio Part 3 of 7) Oral history interview of Marilyn E. Jacox, February 11, 1998 / by Karmal Beal
No full textMaryilyn Jacox begins her discussion with her early interest in science, her education in chemistry and physics, her teaching position at the Mellon Institute and her 15 year collaboration with Dick Milligan. She also recalls her work in free radicals at NBS/NIST (including F-atom reactions in solids and H-atom detachment and acetylene), her mandate to build a laboratory in 1962 upon her arrival at NBS, the Arturim Leonardi Prize which she shared with Dick Milligan, and the Infrared Spectroscopy Glidden Conference
(Audio Part 1 of 3) Oral history interview of Gregory Linteris, March 3, 1998 / with Karma Beal.
No full textGreg Linteris discusses his work in fire suppressants and microgravity research at NIST. He also gives an extensive account of his application and acceptance into the NASA Space Flight Program and his training and work as a payload specialist astronaut onboard the Space Shuttle
(Transcript) Oral history interview of Gregory Linteris, March 3, 1998 / with Karma Beal.
No full textGreg Linteris discusses his work in fire suppressants and microgravity research at NIST. He also gives an extensive account of his application and acceptance into the NASA Space Flight Program and his training and work as a payload specialist astronaut onboard the Space Shuttle
Henry M. Rosenstock
No full textHENRY M. ROSENSTOCK
NBS: 1960 -1982
Birth: February 15, 1928, Mannheim, Germany
Death: September 14, 1982, Portugal
EDUCATION:
City College of New York, BS (Chemistry), 1949
University of Utah, PhD (Physical Chemistry), 1952
PRINCIPAL FIELDS:
Mass spectrometry; gaseous ion energetics and kinetics; Standards Reference Data
POSITIONS HELD AT NBS:
Chief, Mass Spectrometry Section
Chief, Elementary Processes Section
Chief, Chemical Dynamics Section
Institute Scientist, Institute for Materials Research
Senior Scientist, Center for Radiation Research
Director, Ion Energetics Data Center
Senior Scientist, Center for Chemical Physics, Chemical Thermodynamics Division
HONORS:
U.S. Department of Science Silver Medal, 1966
Elected to Phi Beta Kappa, Sigma Xi and Sigma Pi Sigma
MEMBERSHIPS:
Washington Academy of Sciences (Fellow)
PUBLICATIONS:
Authored or co authored 73 technical papers and five books
(Audio Part 2 of 4) Oral history interview of Howard F. McMurdie, January 28, 1998 / by Karma Beal.
No full textHoward McMurdie discusses his 38 year career at NBS. He arrived in 1928 and began work in the Lime and Gypsum Section. Mc Murdie recalls his work in x-ray diffraction, dry cells, jewel bearings, phase equilibria and Portland cement. McMurdie also talks about his research in the Glass Section making synthetic quartz, and his work in the Polymer Division investigating various rubbers and wool fibers. At the end of the interview McMurdie discusses the work of Weir and Van Valhenburg and the history of the diamond cell. He also gives his impressions of the various Directors he served under, the buildings at the "old site" in Van Ness, the Senior Lunch Club, and women and the early days of the Bureau
(Audio Part 2 of 3) Oral History Interviews with Elio Passaglia, July 19, 1988 /by Karma Beal
No full textElio Passaglia recalls his education and industry experience prior to his arrival at NBS. He then highlights his distinguished career at NBS beginning with his work in the Division of Organic and Fibrous Materials. During the reorganization in 1962, he became Chief of the Polymer Physics Section, and collaborated on a very popular ellipsometry textbook. Passaglia also discusses his relationships with Drs. Huntoon and Astin, Earl Schoonover, Rob Thompson and Ernest Ambler. Passaglia talks about the joint efforts between NBS and NIH, the laser and high temperature materials work in the ARPA program, his Visiting Professorship at the University of Colorado, and his important work in the Flammable Fabrics Program
(Audio Part 6 of 7) Oral history interview of Marilyn E. Jacox, February 11, 1998 / by Karmal Beal
No full textMarilyn Jacox discussses the many awards she received in her NBS/NIST career. The awards include: Utica College Outstanding Alumnus Award, Physical Sciences Award from the Washington Academy of Sciences, the Department of Commerce Gold Medal Award, the Federal Woman's Award, the Stratton Award (with Dick Milligan) for ion studies, the Lippincott Award, The Hillebrand Prize of the Chemical Society of Washington, the WISE Lifetime Achievement Award (which requires the recepient to do something of sustained importance to the status of women), the Syracuse University honorary ScD. Marilyn also talks about the changes she observed in the organizational structure of NBS/NIST during her career. Jacox recalls the 1964 reorganization, her time as Section Chief of Photochemistry and the 1991 reorganization of John Lyons