Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “Preparations”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,225 records · Page 68
All sourcesNASA NTRSDOE OSTI
NASA NTRS1978

Low density bismaleimide-carbon microballoon composites

A process is described for constructing for a composite laminate structure which exhibits a high resistance to heat and flame provides safer interior structures for aircraft and submarine compartments. Composite laminate structures are prepared by the bismaleimide resin preimpregnation of a fiberglass cloth to form a face sheet which is bonded with a bismaleimide hot melt adhesive to a porous core structure selected from the group consisting of polyamide paper and bismaleimide-glass fabric which is filled with carbon microballoons. The carbon microballoons are prepared by pyrolyzing phenolic micro-balloons in the presence of nitrogen. A slurry of the carbon microballoons is prepared to fill the porous core structure. The porous core structure and face sheet are bonded to provide panel structures exhibiting increased mechanical capacities and lower oxygen limit values and smoke density values.

Kourtides, D. A.↗
NASA NTRS1978

Pioneer Venus 1978 mission support

The Tracking and Data System and Deep Space Network preparation and support activities for the Pioneer Venus 1978 Mission are described including prelaunch preparations. The status of multiprobe entry preparations and the differential long base interferometry wind measurement experiment are summarized.

Miller, R. B.↗
NASA NTRS1978

Isomer effects on polyimide properties

Thermally stable polyimide polymers were prepared. Parameters explored include asymmetry of substitution, addition of alkyl substituents to an aromatic ring, and an increase in the number of aromatic rings present in the diamine monomer. It is shown that the use of an asymmetrical diamine in the preparation of a polyimide produces a polymer with a markedly lowered glass transition temperature. This is achieved with little or no sacrifice of thermal stability. An alternate approach taken was to prepare imide monomers which are capable of addition-type polymerization.

Stump, B. L.↗
NASA NTRS1978

Automated clinical system for chromosome analysis

An automatic chromosome analysis system is provided wherein a suitably prepared slide with chromosome spreads thereon is placed on the stage of an automated microscope. The automated microscope stage is computer operated to move the slide to enable detection of chromosome spreads on the slide. The X and Y location of each chromosome spread that is detected is stored. The computer measures the chromosomes in a spread, classifies them by group or by type and also prepares a digital karyotype image. The computer system can also prepare a patient report summarizing the result of the analysis and listing suspected abnormalities.

Castleman, K. R.↗
NASA NTRS1979

Obtaining growth hormone from calf blood

The preparation of a growth hormone from human serum was used for the isolation of the hormone from calf serum. The preparation was biologically active - it increased the quantity of the free fatty acids released in rat plasma by 36.4 percent. Electrophoresis in Veronal buffer, ph 8.6, showed the presence of a single fraction having mobility intermediate between that of alpha and beta globulins. Gel filtration through Sephadex G 100 showed an elutriation curve identical to that obtained by the growth hormone prepared from pituitary glands.

Kalchev, L. A.↗
NASA NTRS1979

Compound oxidized styrylphosphine

A process is described for preparing flame resistant, nontoxic vinyl polymers which contain phosphazene groups and which do not emit any toxic or corrosive products when they are oxidatively degraded. Homopolymers, copolymers, and terpolymers of a styrene based monomer are prepared by polymerizing at least one oxidized styrylphosphine monomer from a group of organic azides, or by polymerizing p-diphenylphosphinestyrene and then oxidizing that monomer with an organoazide from the group of (C6H5)2P(O)N3, (C6H5O)2P(O)N3, (C6H5)2C3N3(N3), and C6H5C3N3(N3)2. Copolymers can also be prepared by copolymerizing styrene with at least one oxidized styrylphosphine monomer.

Paciorek, K. J. L.↗
NASA NTRS1980

Evaluation of high-temperature structural adhesives for extended service

Candidate high-temperature stable resin formulations were evaluated for adhesive properties when bonded to titanium treated with various surface preparations. The adhesive formulations included LARC-13, NR150 A2, NR150 B2, NR056X, FM-34, HR-602, and polyphenylquinoxaline. Eight titanium surface preparations were compared for resulting bond strength with the candidate adhesives. After initial evaluation, three adhesive systems (comprised of adhesive, primer, and titanium surface preparation) were selected for further screening. The screening (still in progress) includes cure-cycle optimization and bond properties from 219 K (-65 F) to 505 K (450 F), after isothermal aging at 505 K (450 F) up to 15,000 hours, and after humidity aging at 322 K 9120 F)/ 95 percent R. H. for up to 2000 hours. Larger-area bond capability of the three adhesive system can be demonstrated by fabrication of 30.5 cm (12 in) square titanium honeycomb sandwich and metal-to-metal bonded panels.

Hendricks, C. L.↗
NASA NTRS1981

Investigations related to evaluation of ultramicrofluorometer

High resolution emission and excitation fluorescent spectra were obtained for several samples in an effort to determine the optimum operational design for the instrument. The instrument was used to determine the required nature of a sample which could be detected, and in so doing, several different sample preparation techniques were considered. Numerous experiments were performed to determine the capabilities of the instrument with regard to the detection of suitably prepared virus specimens. Significant results were obtained in several areas. The fluorescent spectra indicated that substantial changes in the laser might be used advantageously to greatly improve the performance of the instrument. In the existing configuration, the instrument was shown to be capable of detecting the presence of suitably prepared virus samples.

Whitcomb, B.↗
NASA NTRS1981

Ultrapure glass optical waveguide development in microgravity by the sol-gel process

Multicomponent, homogeneous, noncrystalline oxide gels can be prepared by the sol-gel process and these gels are promising starting materials for melting glasses in the space environment. The sol-gel process referred to here is based on the polymerization reaction of alkoxysilane with other metal alkoxy compounds or suitable metal salts. Many of the alkoxysilanes or other metal alkoxides are liquids and thus can be purified by distillation. The use of gels offers several advantages such as high purity and lower melting times and temperatures. The sol-gel process is studied for utilization in the preparation of multicomponent ultrapure glass batches for subsequent containerless melting of the batches in space to prepare glass blanks for optical waveguides.

Mukherjee, S. P.↗
NASA NTRS1979

Low dimensional magnetic solids and single crystal elpasolites: Need for improved crystal growing techniques

The need for extensive crystal growing experiments to develop techniques for preparing crystals suitable for magnetic anisotropy measurements and detailed X-ray and neutron diffraction studies is rationalized on the basis of the unique magnetic properties of the materials and their hydrogen bonded structures which have many features in common with metalloenzyme and metalloprotein active sites. Single crystals of the single and mixed lanthanide species are prepared by the Bridgeman technique of gradient solidification of molten samples. The effects of crystal imperfections on the optical properties of these materials are an important part of the projected research. A series of a-amido acid complexes of first row transition metals were prepared which crystallize as infinite linear chains and exhibit low dimensional magnetic ordering (one or two) at temperature below 40 K.

Good, M. L.↗
NASA NTRS1982

Synthesis of perfluorinated polyethers

A series of highly fluorinated acetylenes was prepared and their cyclization reactions were studied. A series of perfluoropolytriazines with -CF2I pendent groups were prepared. These materials can be cured thermally or photochemically to an elastomeric gum. Perfluoropolytriazines with -CN pendent groups were prepared. These materials can be crosslinked by reaction with terephthalonitrile oxide.

Depasquale, R. J.↗
NASA NTRS1982

Critical technology limits to silicon material and sheet production

Earlier studies have indicated that expenditures related to the preparation of high-purity silicon and its conversion to silicon sheet represent from 40 to 52 percent of the cost of the entire panel. The present investigation is concerned with the elements which were selected for study in connection with the Flat-Plate Solar Array (FSA) Project. The first of two technologies which are being developed within the FSA Project involves the conversion of metallurgical-grade silicon through a silane purification process to silicon particles. The second is concerned with the conversion of trichlorosilane to dichlorosilane, and the subsequent production of silicon using modified rod reactors of the Siemens type. With respect to silicon sheet preparation, efforts have been focused both on the preparation of ingots, followed by wafering, and the direct crystallization of molten silicon into a ribbon or film.

Leipold, M. H.↗
NASA NTRS1982

Gels and gel-derived glasses in the Na2O-B2O3-SiO2 system

The containerless melting of high-purity multicomponent homogeneous gels and gel-monoliths offers a unique approach to making ultrapure multicomponent optical glasses in the reduced gravity environment of space. Procedures for preparing and characterizing gels and gel-derived glasses in the Na2O-B2O3-SiO2 system are described. Preparation is based on the polymerization reactions of alkoxysilane with trimethyl borate or boric acid and a suitable sodium compound. The chemistry of the gelling process is discussed in terms of process parameters and the gel compositions. The physicochemical nature of gels prepared by three different procedures were found to be significantly different. IR absorption spectra indicate finite differences in the molecular structures of the different gels. The melting of the gel powders and the transformation of porous gel-monoliths to transparent 'glass' without melting are described.

Mukherjee, S. P.↗
NASA NTRS1984

Group-type hydrocarbon standards for high-performance liquid chromatographic analysis of middistillate fuels

A new high-performance liquid chromatographic (HPLC) method for group-type analysis of middistillate fuels is described. It uses a refractive index detector and standards that are prepared by reacting a portion of the fuel sample with sulfuric acid. A complete analysis of a middistillate fuel for saturates and aromatics (including the preparation of the standard) requires about 15 min if standards for several fuels are prepared simultaneously. From model fuel studies, the method was found to be accurate to within 0.4 vol% saturates or aromatics, and provides a precision of + or - 0.4 vol%. Olefin determinations require an additional 15 min of analysis time. However, this determination is needed only for those fuels displaying a significant olefin response at 200 nm (obtained routinely during the saturated/aromatics analysis procedure). The olefin determination uses the responses of the olefins and the corresponding saturates, as well as the average value of their refractive index sensitivity ratios (1.1). Studied indicated that, although the relative error in the olefins result could reach 10 percent by using this average sensitivity ratio, it was 5 percent for the fuels used in this study. Olefin concentrations as low as 0.1 vol% have been determined using this method.

Otterson, D. A.↗
NASA NTRS1984

A guideline for heavy ion radiation testing for Single Event Upset (SEU)

A guideline for heavy ion radiation testing for single event upset was prepared to assist new experimenters in preparing and directing tests. How to estimate parts vulnerability and select an irradiation facility is described. A broad brush description of JPL equipment is given, certain necessary pre-test procedures are outlined and the roles and testing guidelines for on-site test personnel are indicated. Detailed descriptions of equipment needed to interface with JPL test crew and equipment are not provided, nor does it meet the more generalized and broader requirements of a MIL-STD document. A detailed equipment description is available upon request, and a MIL-STD document is in the early stages of preparation.

Nichols, D. K.↗
NASA NTRS1983

Gels and gel-derived glasses in the system Na2O-B2O3-SiO2

The containerless melting of high-purity multicomponent homogeneous gels and gel monoliths offers a unique approach to making ultrapure multicomponent optical glasses in the reduced gravity environment of space. Procedures for preparing and characterizing gels and gel-derived glasses in the system Na2O-B2O3-SiO2 are described. Preparation is based on the polymerization reactions of alkoxysilane with trimethyl borate or boric acid and a suitable sodium compound. The chemistry of the gelling process is discussed in terms of process parameters and the gel compositions. The physicochemical nature of gels prepared by three different procedures was found to be significantly different. Infrared absorption spectra indicate finite differences in the molecular structures of the different gels. The melting of the gel powders and the transformation of porous gel monoliths to transparent 'glass' without melting are described.

Mukherjee, S. P.↗
NASA NTRS1984

Homogeneity of gels and gel-derived glasses

The significance and implications of gel preparation procedures in controlling the homogeneity of multicomponent oxide gels are discussed. The role of physicochemical factors such as the structure and chemical reactivities of alkoxides, the formation of double-metal alkoxides, and the nature of solvent(s) are critically analyzed in the context of homogeneity of gels during gelation. Three procedures for preparing gels in the SiO2-B2O3-Na2O system are examined in the context of cation distribution. Light scattering results for glasses in the SiO2-B2O3-Na2O system prepared by both the gel technique and the conventional technique are examined.

Mukherjee, S. P.↗
NASA NTRS1985

Railroad safety program, volume 1

Since 1981, the Federal Railroad Administration (FRA) has annually prepared a National Inspection Plan (NIP) whose purpose is to summarize regional efforts to improve railroad transportation safety. The research concluded on the following tasks including the problems, conclusions and recommendations associated with these tasks is summarized: (1) the preparation of the 1983 NIP, with recommended procedures for improving future NIPs; (2) the development of an outline for the 1984 NIP, including a methodology for the allocation of inspection resources and other specialized regional activities; (3) the management and development of the 1984 NIP; and (4) the development of an instruction manual to be used in the preparation of future NIPs.

Source record↗