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Amorphous calcium phosphate-based bioactive polymeric composites for mineralized tissue regeneration
No full textAmorphous calcium phosphate (ACP), a postulated precursor in the formation of biological hydroxyapatite, has been evaluated as a filler phase in bioactive polymeric composites that utilize dental monomers to form the matrix phase on polymerization. In addition to excellent biocompatibility, these composites provided sustained release of calcium and phosphate ions into simulated saliva milieus. In an effort to enhance the physicochemical and mechanical properties and extend the utility of remineralizing ACP composites to a greater variety of dental applications, we have focused on: a) hybridizing ACP by introducing silica and/or zirconia, b) assessing the efficacy of potential coupling agents, c) investigating the effects of chemical structure and compositional variation of the resin matrices on the mechanical strength and ion-releasing properties of the composites, and d) improving the intrinsic adhesiveness of composites by using bifunctional monomers with an affinity for tooth structure in resin formulations. Si- and Zr-modified ACPs along with several monomer systems are found useful in formulating composites with improved mechanical and remineralizing properties. Structure-property studies have proven helpful in advancing our understanding of the remineralizing behavior of these bioactive composites. It is expected that this knowledge base will direct future research and lead to clinically valuable products, especially therapeutic materials appropriate for the healing or even regeneration of defective teeth and bone structures
Review of instrumented indentation
No full textInstrumented indentation, also known as depth-sensing indentation or nanoindentation, is increasingly being used to probe the mechanical response of materials from metals and ceramics to polymeric and biological materials. The additional levels of control, sensitivity, and data acquisition offered by instrumented indentation systems have resulted in numerous advances in materials science, particularly regarding fundamental mechanisms of mechanical behavior at micrometer and even sub-micrometer length scales. Continued improvements of instrumented indentation testing towards absolute quantification of a wide range of material properties and behavior will require advances in instrument calibration, measurement protocols, and analysis tools and techniques. In this paper, an overview of instrumented indentation is given with regard to current instrument technology and analysis methods. Research efforts at the National Institute of Standards and Technology (NIST) aimed at improving the related measurement science are discussed
(Audio Part 1 of 3) Oral history interview of John Hoffman, July 21, 2003
No full textDr. John Hoffman discusses his long career at NIST. His career spanned the years 1954 to 1982, during which time he was in various leadership positions, including Director of the Institute for Materials Research and Director of the National Measurement laboratory
Theodore E. Madey
No full textTHEODORE E. MADEY
NBS/NIST: 1963 - 1988
Birth: October 24, 1937, Wilmington, Delaware
Death: July 27, 2008
Education:
Loyola College, Baltimore: BS (Physics), 1959
University of Notre Dame: PhD (Physics), 1963
Principal fields:
Physics and chemistry of surfaces and interfaces
Positions held at NBS/NIST:
NRC/NBS Postdoctoral Fellow
Physicist, Surface Chemistry Section
Deputy Chief, Surface Science Division
Leader, Surface Structure and Kinetics Group
NBS Fellow
Honors:
U.S. Department of Commerce: Silver Medal, 1973; Gold Medal, 1981
Stratton Award (joint with J.T. Yates, Jr.), 1978
E.U. Condon Award, 1982
Presidential Rank Award, Senior Executive Service, 1988
Medard E. Welch Award, American Vacuum Society, 1985
E.W. Mueller Award, University of Wisconsin, 1991
University of Wroclaw, Poland: Doctor Honoris Causa, 2003
Memberships:
American Physical Society (Fellow)
American Vacuum Society (President, Fellow)
International Union for Vacuum Science, Technique and Applications (Secretary-General, President)
American Institute of Physics, Executive Committee of Governing Board
Publications:
Over 360 published papers, including:
Madey, T.E. and J.T. Yates, Jr. “Electron-Stimulated Desorption as a Tool for Studies of Chemisorption: A Review,” J. Vac. Sci. and Technol. 8 (1971) 525
Madey, T.E. “Electron and Photon Stimulated Desorption: Probes of Structure and Bonding at Surfaces,” Science 234 (1986) 316
Thiel, P.S. and T.E. Madey, “The Interaction of Water with Solid Surfaces: Fundamental Aspects,” Surface Science Reports 7 (1987) 21
Carl O. Muehlhause
No full textCarl O. Muehlhause
Inducted: 2003
Citation: For leadership in the design, building, and activation of a long lasting and visionary nuclear research facility
Tenure: 1958-1982
Birth: 1918, Baltimore, Maryland
Death: 2004
Education:
University of Virginia, BS (Physics), 1940
University of Illinois, MS (Physics), 1941; PhD (Physics) 1943
Positions held:
Chief, NBS Research Reactor Program
Chief, Reactor Radiation Division
Director, Center for Radiation Research
Scientific Assistant to the Director, Institute for Applied Technology
Senior Scientific Advisor, Center for Consumer Product Technology
NIST Representative, OST-NBS Risk Analysis Study
Honors:
U.S. Department of Commerce: Gold Medal
Membership:
American Physical Society (Fellow)
Washington Academy of Science (Fellow)
New York Academy of Science (Fellow)
American Nuclear Society, (President, Washington Chapter)
Sigma Xi
Publications:
40 publications in nuclear physics, nuclear engineering, and economics, including:
“Capture Cross Sections for Slow Neutrons: Small Capture Cross Sections,” (with M. Goldhaber), Phys. Rev. (1946)
“On Spin Dependent Nuclear Radii,” Phys. Rev. (1950)
“Antineutrino Flux from a Reactor,” Phys. Rev. (1957)
“Cost-Benefit Framework for Consumer Product-Safety Standards” J. Res. Nat. Bur. Stand. (1978
(Audio Part 2 of 3) Oral history interview of George Porter, March 3, 2003 / by Norm Belecki, Reeves Tilley, and Lisa Greenhouse
No full textGeorge Porter, former head of the Personnel Division of NBS, discusses his nearly 24 years working at the Bureau. Porter came to NBS in 1950 and was Chief of the Personnel Division from 1951-1974. Porter discusses the attitudes of scientists at the Bureau towards the civil service system in the 1950s and 1960s, management and staff relations, and notable events including the AD-X2 controversy. Also mentioned are the NBS Graduate School Program, the relocation of the Bureau from Washington, D.C. to Gaithersburg, and the role of women in the Bureau
Oral history interview of George Porter, March 3, 2003 / by Norm Belecki, Reeves Tilley, and Lisa Greenhouse
No full textGeorge Porter, former head of the Personnel Division of NBS, discusses his nearly 24 years working at the Bureau. Porter came to NBS in 1950 and was Chief of the Personnel Division from 1951-1974. Porter discusses the attitudes of scientists at the Bureau towards the civil service system in the 1950s and 1960s, management and staff relations, and notable events including the AD-X2 controversy. Also mentioned are the NBS Graduate School Program, the relocation of the Bureau from Washington, D.C. to Gaithersburg, and the role of women in the Bureau
Towards high accuracy reflectometry for extreme-ultraviolet lithography
No full textCurrently the most demanding application of extreme ultraviolet optics is connected with the development of extreme ultraviolet lithography. Not only does each of the Mo/Si multilayer extreme-ultraviolet stepper mirrors require the highest attainable reflectivity at 13 nm ( nearly 70 %), but the central wavelength of the reflectivity of these mirrors must be measured with a wavelength repeatability of 0.001 nm and the peak reflectivity of the reflective masks with a repeatability of 0.12 %. We report on two upgrades of our NIST/DARPA Reflectometry Facility that have given us the ability to achieve 0.1 % repeatability and 0.3 % absolute uncertainty in our reflectivity measurements. A third upgrade, a monochromator with thermal and mechanical stability for improved wavelength repeatability, is currently in the design phase