NASA Scientific and Technical Aerospace Reports

program with emphasis on the advanced technologies that form the foundation of the program.
Author
Aircraft Noise; Supersonic Aircraft; Noise Reduction
20040111475 Houston Univ., TX
Chemical Emulation of Radiation Pinning Center Geometries in High Temperature Superconductors
Weinstein, Roy; Jul. 31, 2004; 11 pp.; In English
Contract(s)/Grant(s): DAAD19-01-1-0535
Report No.(s): AD-A425418; ARO-41890.14-MS; No Copyright; Avail: CASI; A03, Hardcopy
Discovery of sub-micron size deposits of (U, Zr, Nd, Ba, 0) in Nd123 enabled application of the U/n method to Nd123,
resulting in world record J(sub c). Discovery of an entire class of 200-400 nm size, double perovskite pinning centers,
(A,B)REBa(sub 2)O(sub 6), led to ^20 new chemical ‘point’ pinning centers, and enabled replacement of successful but
expensive and radioactive (U(sub 0.6)Pt(sub 0.4))REBa(sub 2)O(sub 6) pinning centers with inexpensive, non-radioactive
(W(sub 0.5),Zr(sub 0.5()REBa(sub 2)O(sub 6). Additional studies proved that the parent compound used for additives strongly
effect the critical parameter of pinning center size. Theoretical studies of the cause of decreasing J(sub c), when large ion
fluences are used to induce pinning, led to postulating a new class of pinning centers based on multiple- in-line-damage
(MILD). Achievement of self-assembling chemical columnar structures in YBCO proved the feasibility of our ultimate goal
of producing such chemical pinning centers in small enough diameter to play the role of ideal pinning centers.
DTIC
High Temperature Superconductors; Pinning
20040111511 Academy of Sciences (USSR), Pushchino
Assessment of the Genotoxic Effects of High Peak- Power Pulsed Electromagnetic Fields
Chemeris, Nikolai; Jun. 2003; 29 pp.; In English
Report No.(s): AD-A425489; ISTC-RN-2350; No Copyright; Avail: CASI; A03, Hardcopy
This report results from a contract tasking Russian Academy of Sciences as follows: Because of the widespread increase
in man-made sources of electromagnetic fields (EMFs), including high peak-power pulsed EMF (HPPP EMF), it has become
important to study the health consequences, including possible genotoxic effects of such fields. Because of the simultaneous
increase in other environmental toxins, it is difficult to isolate the effects of EMFs in natural human populations. Therefore,
this question must be studied under controlled laboratory conditions. The objective of the proposed project is the detection of
possible HPPP EMF effects on biological systems at the subcellular and molecular levels. The primary effort will be to assess
the effects of HPPP EMF on the genetic material and on intracellular biochemical processes that regulate DNA replication.
In doing so, the researchers will develop and modify special methods for the analysis of nucleoid DNA structure on the basis
of the single cell gel electrophoresis (comet) assay. Improvements in this method will raise its sensitivity, reliability, and
rapidity, as well as decrease its cost. The researchers plan to computerize the method using digital imaging and image analysis
techniques. Results will help determine the basic biological effects of HPPP EMF and help provide a broader basis for setting
appropriate safety standards.
DTIC
Electromagnetic Fields; Toxicity; Toxins and Antitoxins
20040111572 New York Univ., New York, NY
Investigation of Electromagnetic Field Propagation in Reverse Saturable Absorbers
McLaughlin, David W.; Potasek, Mary; Jul. 5, 2004; 50 pp.; In English
Contract(s)/Grant(s): F49620-01-1-0086
Report No.(s): AD-A425624; No Copyright; Avail: CASI; A03, Hardcopy
We have developed and implemented a numerical technique for the propagation of the electromagnetic field in a five-level
reverse saturable absorber medium, which includes the nonlinear Kerr effect and dispersion. The numerical method combines
a split step beam propagation method with the Crank- Nicholson method. Our numerical results and calculations enable the
prediction of nonlinear absorption using experimentally measurable material parameters such as the absorption cross-sections
and decay rates. We also investigated the interplay between the optical pulse properties such as the temporal pulse width,
spatial radius, incident energy and the carrier dynamics, and nonlinear absorption of the reverse saturable absorber.
DTIC
Electromagnetic Fields; Electromagnetic Wave Transmission
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