9,234 research outputs found
Interdisciplinary materials research including fundamental physics and chemistry of materials, environmental effects and related problems Semiannual progress report, Sep. 1, 1967 - Feb. 29, 1968
Interdisciplinary materials research in inorganic nonmetallic materials, metallic solids, polymers, and solid state physic
Interdisciplinary Materials Research Program Semiannual Progress Report, 1 Mar. - 31 Aug. 1967
Materials science research on inorganic nonmetallic materials, metallic solids, polymers, and solid state physic
Development of the technology for the fabrication of reliable laminar from control panels
Materials were assessed and fabrication techniques were developed for use in the manufacture of wing surface materials compatible with the application of both aluminum alloys and nonmetallic composites. The concepts investigated included perforations and slots in the metallic test panels and microporosity and perforations in the composite test panels. Perforations were produced in the metallic test panels by the electron beam process and slots were developed by controlled gaps between the metal sheets. Microporosity was produced in the composite test panels by the resin bleed process, and perforations were produced by the fugitive fiber technique. Each of these concepts was fabricated into test panels, and air flow tests were conducted on the panels
Analysis of debris from Spacelab Space Life Sciences-1
Airborne microbiological and particulate contamination generated aboard Spacelab modules is a potential safety hazard. In order to shed light on the characteristics of these contaminants, microbial and chemical/particulate analyses were performed on debris vacuumed from cabin and avionics air filters in the Space Life Sciences-1 (SLS-1) module of the Space Transportation System 40 (STS-40) mission 1 month after landing. The debris was sorted into categories (e.g., metal, nonmetal, hair/fur, synthetic fibers, food particles, insect fragments, etc.). Elemental analysis of particles was done by energy dispersive analysis of x rays (metals) and Fourier transform infrared spectroscopy (nonmetals). Scanning electron micrographs were done of most particles. Microbiological samples were grown on R2A culture medium and identified. Clothing fibers dominated the debris by volume. Other particles, all attributed to the crew, resulted from abrasions and impacts during missions operations (e.g., paint chips, plastic, electronic scraps and clothing fibers). All bacterial species identified are commonly found in the atmosphere or on the human body. Bacillus sp. was the most frequently seen bacterium. One of the bacterial species, Enterobacter agglomerans, could cause illness in crew members with depressed immune systems
Regulation of the burning parameters for energetic materials based on ammonium nitrate and metal nanopowders and nonmetals
The results of study for the influence of metallic and nonmetallic nanopowders on the combustion parameters of mixed energetic materials based on ammonium nitrate are presented and compared with materials, containing micropowders of metals. The catalytic activity rank of the powders is plotted showing their effect on the combustion characteristics of mixed energetic materials
Substrate-induced half-metallic property in epitaxial silicene
For most practical applications in electronic devices, two-dimensional
materials should be transferred onto semiconducting or insulating substrates,
since they are usually generated on metallic substrates. However, the transfer
often leads to wrinkles, damages, contaminations and so on which would destroy
the intrinsic properties of samples. Thus, generating two-dimensional materials
directly on nonmetallic substrates has been a desirable goal for a long time.
Here, via a swarm structure search method and density functional theory, we
employed an insulating N-terminated cubic boron nitride(111) surface as a
substrate for the generation of silicene. The result shows that the silicene
behaves as a ferromagnetic half-metal because of the strong interaction between
silicon and surface nitrogen atoms. The magnetic moments are mainly located on
surface nitrogen sites without bonding silicon atoms and the value is about
0.12 uB. In spin-up channel, it behaves as a direct band gap semiconductor with
a gap of around 1.35 eV, while it exhibits metallic characteristic in spin-down
channel, and the half-metallic band gap is about 0.11 eV. Besides, both the
magnetic and electronic properties are not sensitive to the external
compressive strain. This work maybe open a way for the utility of silicene in
spintronic field
High-Pressure Oxygen Test Evaluations
The relevance of impact sensitivity testing to the development of the space shuttle main engine is discussed in the light of the special requirements for the engine. The background and history of the evolution of liquid and gaseous oxygen testing techniques and philosophy is discussed also. The parameters critical to reliable testing are treated in considerable detail, and test apparatus and procedures are described and discussed. Materials threshold sensitivity determination procedures are considered and a decision logic diagram for sensitivity threshold determination was plotted. Finally, high-pressure materials sensitivity test data are given for selected metallic and nonmetallic materials
Reentry vehicle leading edge Patent
Leading edge design for hypersonic reentry vehicle
Metal-nonmetal transition in LixCoO2 thin film and thermopower enhancement at high Li concentration
We investigate the transport properties of LixCoO2 thin films whose
resistivities are nearly an order of magnitude lower than those of the bulk
polycrystals. A metal-nonmetal transition occurs at ~0.8 in a biphasic domain,
and the Seebeck coefficient (S) is drastically increased at ~140 K (= T*) with
increasing the Li concentration to show a peak of magnitude ~120 \muV/K in the
S-T curve of x = 0.87. We show that T* corresponds to a crossover temperature
in the conduction, most likely reflecting the correlation-induced temperature
dependence in the low-energy excitations
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