1,043 research outputs found
Experimental study of ceramic coated tip seals for turbojet engines
Ceramic gas-path seals were fabricated and successfully operated over 1000 cycles from flight idle to maximum power in a small turboshaft engine. The seals were fabricated by plasma spraying zirconia over a NiCoCrAlX bond boat on the Haynes 25 substrate. Coolant-side substrate temperatures and related engine parameters were recorded. Post-test inspection revealed mudflat surface cracking with penetration to the ceramic bond-coat interface
High temperature x ray diffraction determination of the body-centered-cubic-face-centered-cubic transformation temperature in (Fe 70Ni 30) 88Zr 7B 4Cu 1 nanocomposites
In situ high-temperature x ray diffraction and magnetization measurements were performed on a melt-spun (Fe70Ni30)88Zr7B4Cu1 amorphous alloy to follow its structural evolution. At 728 K, a bcc-FeNi phase was observed as the primary crystallization product followed by transformation to an fcc phase rv773 K. During cooling to room temperature, the fcc-to-bcc transformation was not observed, and the metastable fcc-NiFe phase was retained at room temperature
Adolescent Burmese Refugees Perspectives on Determinants of Health
Over 70,000 Burmese refugees have resettled in the United States in the past decade. While Burmese adolescents quickly acculturate into American society, their perspectives on health are not well-known. The purpose of this study was to identify adolescent Burmese refugee perspectives on determinants of health and health-related experiences after resettlement. In this qualitative study, Burmese adolescents took photographs depicting health-related experiences that were used as elicitation tools during focus groups. These discussions were recorded, transcribed, and analyzed for themes. Participants described positive determinants of health, including family and church. Rampant tobacco use was identified by the participants as a determinant of poor health within the Burmese community. Notably, the participants were proud to serve as liaisons within their community, despite the stressful nature of this role. Our results highlight the need to screen this population for anxiety, secondary to serving as a liaison for their community, as well as tobacco use
Hole Doping Effects on Spin-gapped Na2Cu2TeO6 via Topochemical Na Deficiency
We report the magnetic susceptibility and NMR studies of a spin-gapped
layered compound
Na2Cu2TeO6 (the spin gap 250 K), the hole doping effect on the
Cu2TeO6 plane via a topochemical Na deficiency by soft chemical treatment, and
the static spin vacancy effect by nonmagnetic impurity Zn substitution for Cu.
A finite Knight shift at the Te site was observed for pure
Na2Cu2TeO6.
The negative hyperfine coupling constant is an evidence for
the existence of a superexchange pathway of the Cu-O-Te-O-Cu bond. It turned
out that both the Na deficiency and Zn impurities induce a Curie-type magnetism
in the uniform spin susceptibility in an external magnetic field of 1 T, but
only the Zn impurities enhance the low-temperature Na nuclear
spin-lattice relaxation rate whereas the Na deficiency suppresses it. A spin
glass behavior was observed for the Na-deficient samples but not for the
Zn-substituted samples. The dynamics of the unpaired moments of the doped holes
are different from that of the spin vacancy in the spin-gapped Cu2TeO6 planes.Comment: 4 pages, 7 figures, to be published in J. Phys. Soc. Jpn. Vol. 75,
No. 8 (2006
From Opportunity to Necessity: Development of an Asynchronous Online Interprofessional Learning Experience
Incorporating interprofessional collaboration competencies into both undergraduate pre-licensure and graduate health science students poses challenges for academic health science centers. Certain student groups may have less opportunity to participate in interprofessional learning experiences due to demands of individual programs of study and conflicts in scheduling time with other disciplines. A group of interprofessional higher education faculty members created an innovative online asynchronous interprofessional experience with the primary goals of meeting accreditation standards for specific programs and providing interprofessional education (IPE) to students who were unable to participate in traditional face-to-face IPE experiences already established at the institution. This guide will highlight the process of design and development of the learning opportunity, from conception to implementation. The pilot of the asynchronous online IPE experience served as a model for the transition of the original in-person model to virtual IPE during the COVID-19 pandemic
High speed electric motors based on high performance novel soft magnets
Novel Co-based soft magnetic materials are presented as a potential substitute for electrical steels in high speed motors for current industry applications. The low losses, high permeabilities, and good mechanical strength of these materials enable application in high rotational speed induction machines. Here, we present a finite element analysis of Parallel Path Magnetic Technology rotating motors constructed with both silicon steel and Co-based nanocomposite. The later achieved a 70% size reduction and an 83% reduction on NdFeB magnet volume with respect to a similar Si-steel design.Fil: Silveyra, Josefina MarÃa. Universidad de Buenos Aires. Facultad de Ingenieria. Departamento de Fisica. Laboratorio de Sólidos Amorfos; Argentina. Consejo Nacional de Investigaciones CientÃficas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de TecnologÃas y Ciencias de la IngenierÃa; Argentina; ArgentinaFil: Leary, A. M.. University Of Carnegie Mellon; Estados UnidosFil: DeGeorge, V.. University Of Carnegie Mellon; Estados UnidosFil: Simizu, S.. Advanced Materials Corporation; Estados UnidosFil: McHenry, M. E.. University Of Carnegie Mellon; Estados Unido
The effect of distributed exchange parameters on magnetocaloric refrigeration capacity in amorphous and nanocomposite materials
The temperature dependent magnetization of nanocomposite alloys has been fit with a modified Handrich-Kobe equation with an asymmetric exchange fluctuation parameter combined with the Arrott-Noakes equation. The two equations of state are combined to calculate the entropy change in the magnetocaloric effect associated with the ferromagnetic to paramagnetic phase transformation. The complete fit for the M(T) of (Fe70Ni30)88Zr7B4Cu nanocomposite powder is accomplished by combining the two theories. We investigate the broadening of the second-order transition arising from asymmetric exchange parameters and resulting from the fluctuations of interatomic spacing found in an amorphous matrix and the asymmetric dependence of exchange energy on interatomic spacing. The magnetic entropy curve revealed extra broadening with a refrigeration capacity (RC) value of 135 J/kg at 5 T, which is comparable to (Fe76Cr8-xMoxCu1B15) ribbons, which have a RC value of 180 J/kg for the same applied field. Broadening of the magnetic entropy can lead to larger RC values and a wider working temperature range, making nanocomposite alloys promising for magnetocaloric applications
Nano granular metallic Fe - oxygen deficient TiO composite films: A room temperature, highly carrier polarized magnetic semiconductor
Nano granular metallic iron (Fe) and titanium dioxide (TiO) were
co-deposited on (100) lanthanum aluminate (LaAlO) substrates in a low
oxygen chamber pressure using a pulsed laser ablation deposition (PLD)
technique. The co-deposition of Fe and TiO resulted in 10 nm
metallic Fe spherical grains suspended within a TiO matrix. The
films show ferromagnetic behavior with a saturation magnetization of 3100 Gauss
at room temperature. Our estimate of the saturation magnetization based on the
size and distribution of the Fe spheres agreed well with the measured value.
The film composite structure was characterized as p-type magnetic semiconductor
at 300 K with a carrier density of the order of . The
hole carriers were excited at the interface between the nano granular Fe and
TiO matrix similar to holes excited in the metal/n-type
semiconductor interface commonly observed in Metal-Oxide-Semiconductor (MOS)
devices. From the large anomalous Hall effect directly observed in these films
it follows that the holes at the interface were strongly spin polarized.
Structure and magneto transport properties suggested that these PLD films have
potential nano spintronics applications.Comment: 6 pages in Latex including 8 figure
Spin Dynamics near the Superconductor-to-Insulator Transition in Impurity-Doped YBa2Cu4O8
We studied low-frequency spin dynamics near the impurity-induced
superconductor-to-insulator transition for underdoped high-Tc superconductor
YBa2(Cu1-xMx)4O8 (M=Ni, Zn) using the Cu nuclear quadrupole resonance (NQR)
spin-echo technique. We observed remarkable suppression of the normal-state
pseudo spin-gap and a loss of Cu NQR spectrum intensity at low temperatures
around the critical impurity concentration.Comment: 6 pages, 4 figures. To be published in J. Phys. Soc. Jpn. Vol.70,
No.7 (2001
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