3,054 research outputs found
Evaluation of an advanced directionally solidified gamma/gamma'-alpha Mo eutectic alloy
An attempt was made to improve on the properties of the candidate jet engine turbine blade material AG-60, a gamma/gamma prime-alpha Mo eutectic composite. Alloy 38 (AG-170) was evaluated in the greatest detail. This alloy, Ni-5.88 A1-29.74 Mo-1.65 V-1.2C Re (weight percent), represents an improvement beyond AG-60, based on mechanical testing of the transverse and/or longitudinal orientations over a range of temperatures in tension, shear, rupture, and rupture after thermal exposure. It is likely that other alloys in the study represent a similar improvement
A CONNECTION BETWEEN MORAL IMPERATIVE AND WOMEN’S LEADERSHIP?
This paper describes a qualitative study of two school districts’ efforts to support school leaders in developing the knowledge and skills to analyze, understand, and transform system inequities. The results suggest that, despite being armed with knowledge and skills, leaders may be reluctant to act even when doing so is within the scope of their authority. This work draws from Fullan’s (2003) concept of moral imperative and examines the connection between moral imperative and women’s ways of leading. The findings have implications for educational leadership programs that seek to prepare school leaders capable of challenging and changing inequitable systems
Bonded Cumomer Analysis of Human Melanoma Metabolism Monitored by 13C NMR Spectroscopy of Perfused Tumor Cells.
A network model for the determination of tumor metabolic fluxes from (13)C NMR kinetic isotopomer data has been developed and validated with perfused human DB-1 melanoma cells carrying the BRAF V600E mutation, which promotes oxidative metabolism. The model generated in the bonded cumomer formalism describes key pathways of tumor intermediary metabolism and yields dynamic curves for positional isotopic enrichment and spin-spin multiplets. Cells attached to microcarrier beads were perfused with 26 mm [1,6-(13)C2]glucose under normoxic conditions at 37 °C and monitored by (13)C NMR spectroscopy. Excellent agreement between model-predicted and experimentally measured values of the rates of oxygen and glucose consumption, lactate production, and glutamate pool size validated the model. ATP production by glycolytic and oxidative metabolism were compared under hyperglycemic normoxic conditions; 51% of the energy came from oxidative phosphorylation and 49% came from glycolysis. Even though the rate of glutamine uptake was ∼50% of the tricarboxylic acid cycle flux, the rate of ATP production from glutamine was essentially zero (no glutaminolysis). De novo fatty acid production was ∼6% of the tricarboxylic acid cycle flux. The oxidative pentose phosphate pathway flux was 3.6% of glycolysis, and three non-oxidative pentose phosphate pathway exchange fluxes were calculated. Mass spectrometry was then used to compare fluxes through various pathways under hyperglycemic (26 mm) and euglycemic (5 mm) conditions. Under euglycemic conditions glutamine uptake doubled, but ATP production from glutamine did not significantly change. A new parameter measuring the Warburg effect (the ratio of lactate production flux to pyruvate influx through the mitochondrial pyruvate carrier) was calculated to be 21, close to upper limit of oxidative metabolism
Rancang Bangun dan Pengujian Pengering Jamur Tiram dengan Satu Kolektor Surya
Indonesia merupakan negara tropis yang memiliki iklim yang baik untuk pertanian. Di Indonesia terdapat dua musim yaitu musim panas dan musim hujan. Hasil pertanian tentunya negara yang mayoritas agraris dan memiliki zona iklim tropis Jamur merupakan tumbuhan alami yang tidak mengandung klorofil. Dimana pada alat terjadi dua jenis perpindahan panas yaitu secara radiasi dan konveksi. Perancangan alat dilakukan dengan langkah pertama yaitu membuat kerangka, rangka utama berukuran 1443 x 2379 x 1254 mm dan kolektor berukuran 1014 x 500 x 35 mm, kemudian untuk menyusun kolektor mulai dari ACP, styrofoam, rockwoll, plat absorber, dan ditutup dengan kaca, dan rak penampung yang berukuran 500 x 400 x 35 mm. dimana prinsip kerja mesin yaitu mengalirkan panas yang telah diserap melalui kolektor tepat nya pada plat absorber dan dialirkan kedalam ruang pengering. Berdasarkan hasil pengujian maka disimpulkan bahwa rak ke 4 merupakan rak yang paling cepat panas dengan kadar air yang tersisa 2,94 %, dan rak 1 merupakan rak yang paling lambat panas dengan kadar air yang tersisa 22,87 %
Fishery dynamics of the California market squid (Loligo opalescens), as measured by satellite remote sensing
Novel data on the spatial and temporal distribution of fishing effort and population abundance are presented for the market squid fishery (Loligo opalescens) in the Southern California Bight, 1992−2000. Fishing effort was measured by the detection of boat lights by the Defense Meteorological Satellite Program (DMSP) Operational Linescan System (OLS). Visual confirmation of fishing vessels by nocturnal aerial surveys indicated that lights detected by satellites are reliable indicators of fishing effort. Overall, fishing activity was concentrated off the following Channel Islands: Santa Rosa, Santa Cruz, Anacapa, and Santa Catalina. Fishing activity occurred at depths of 100 m or less. Landings, effort, and squid abundance (measured as landings per unit of effort, LPUE) markedly declined during the 1997−98 El Niño; landings and LPUE increased afterwards. Within a fishing season, the location of fishing activity shifted from the northern shores of Santa Rosa and Santa Cruz Islands in October, the typical starting date for squid fishing in the Bight, to the southern shores by March, the typical end of the squid season. Light detection by satellites offers a source of fine-scale spatial and temporal data on fishing effort for the market squid fishery off California, and these data can be integrated with environmental data and fishing logbook data in the development of a management plan
The Nainital-Cape Survey -- II:Report for pulsation in five chemically peculiar A-type stars and presentation of 140 null results
To search photometric variability in chemically peculiar A type stars in the
northern hemisphere. High-speed photometric observations of Ap and Am star
candidates have been carried out from ARIES (Manora Peak, Nainital) using a
three-channel fast photometer attached to the ARIES 104-cm Sampurnanand
telescope. This paper presents three new variables: HD 113878, HD 118660 and HD
207561. During the time span of the survey (1999 December to 2004 January)
pulsations of the Sct type were also found for the two evolved Am
stars HD 102480 and HD 98851, as reported in Joshi et al. (2002, 2003).
Additionally, we present 140 null results of the survey for this time span. The
star HD 113878 pulsates with a period of 2.31 hr, which is typical of
Sct stars. HD 118660 exhibits multi-periodic variability with a prominent
period of nearly 1 hr. These periods need to be investigated and make HD 118660
a particularly interesting target for further observations. For HD 207561, a
star classified as Am, a probable pulsation with a period of 6 min was found in
the light curves obtained on two consecutive nights. Both HD 102480 and HD
98851 exhibit unusual alternating high and low amplitude maxima, with a period
ratio of 2:1. The analysis of the null results confirms the photometric quality
of the NainitalComment: 14 pages, 13 figures, Accepted for publication in A&
The role of hole transport between dyes in solid-state dye-sensitized solar cells
In dye-sensitized solar cells (DSSCs)
photogenerated positive charges
are normally considered to be carried away from the dyes by a separate
phase of hole-transporting material (HTM). We show that there can
also be significant transport within the dye monolayer itself before
the hole reaches the HTM. We quantify the fraction of dye regeneration
in solid-state DSSCs that can be attributed to this process. By using
cyclic voltammetry and transient anisotropy spectroscopy, we demonstrate
that the rate of interdye hole transport is prevented both on micrometer
and nanometer length scales by reducing the dye loading on the TiO<sub>2</sub> surface. The dye regeneration yield is quantified for films
with high and low dye loadings (with and without hole percolation
in the dye monolayer) infiltrated with varying levels of HTM. Interdye
hole transport can account for >50% of the overall dye regeneration
with low HTM pore filling. This is reduced to about 5% when the infiltration
of the HTM in the pores is optimized in 2 μm thick films. Finally,
we use hole transport in the dye monolayer to characterize the spatial
distribution of the HTM phase in the pores of the dyed mesoporous
TiO<sub>2</sub>
Discovery of a cluster of galaxies behind the Milky Way: X-ray and optical observations
We report the discovery of Cl 2334+48, a rich cluster of galaxies in the Zone
of Avoidance, identified in public images from the XMM-Newton archive. We
present the main properties of this cluster using the XMM-Newton X-ray data,
along with new optical spectroscopic and photometric observations. Cl 2334+48
is located at z = 0.271 +/- 0.001, as derived from the optical spectrum of the
brightest member galaxy. Such redshift agrees with a determination from the
X-ray spectrum (z = 0.263 (+0.012/-0.010)), in which an intense emission line
is matched to the rest wavelength of the Fe Kalpha complex. Its intracluster
medium has a plasma temperature of 4.92 (+0.50/-0.48) keV, sub-solar abundance
(0.38 +/- 0.12 Zsun), and a bolometric luminosity of 3.2 x 10^44 erg/s. A
density contrast delta = 2500 is obtained in a radius of 0.5 Mpc/h70, and the
corresponding enclosed mass is 1.5 x 10^14 Msun. Optical images show an
enhancement of g'-i' > 2.5 galaxies around the central galaxy, as expected if
these were cluster members. The central object is a luminous E-type galaxy,
which is displaced ~ 40 kpc/h70 from the cluster X-ray center. In addition, it
has a neighbouring arc-like feature (~ 22" or 90 kpc/h70 from it), probably due
to strong gravitational lensing. The discovery of Cl 2334+48 emphasises the
remarkable capability of the XMM-Newton to reveal new clusters of galaxies in
the Zone of Avoidance.Comment: 9 pages, 11 figures, Accepted for publication in A&A (on July 12,
2006
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