95 research outputs found
Superspace Group Approach to the Crystal Structure of Thermoelectric Higher Manganese Silicides MnSi
Design and power generation of tilted Cu/Fe2V(Al0.9Si0.1) multilayers via the transverse thermoelectric effect
Magnetic Full-Heusler Compounds for Thermoelectric Applications
Full-Heusler compounds exhibit a variety of magnetic properties such as non-magnetism, ferromagnetism, ferrimagnetism and anti-ferromagnetism. In recent years, they have attracted significant attention as potential thermoelectric (TE) materials that convert thermal energy directly into electricity. This chapter reviews the theoretical and experimental studies on the TE properties of magnetic full-Heusler compounds. In Section 1, a brief outline of TE power generation is described. Section 2 introduces the crystal structures and magnetic properties of full-Heusler compounds. The TE properties of full-Heusler compounds are presented in Sections 3 and 4. The relationship between magnetism, TE properties and order degree of full-Heusler compounds is elaborated
Enhancement of average thermoelectric figure of merit by increasing the grain-size of Mg_(3.2)Sb_(1.5)Bi_(0.49)Te_(0.01)
Zintl compound n-type Mg_3(Sb,Bi)_2 was recently found to exhibit excellent thermoelectric figure of merit zT (∼1.5 at around 700 K). To improve the thermoelectric performance in the whole temperature range of operation from room temperature to 720 K, we investigated how the grain size of sintered samples influences electronic and thermal transport. By increasing the average grain size from 1.0 μm to 7.8 μm, the Hall mobility below 500 K was significantly improved, possibly due to suppression of grain boundary scattering. We also confirmed that the thermal conductivity did not change by increasing the grain size. Consequently, the sample with larger grains exhibited enhanced average zT. The calculated efficiency of thermoelectric power generation reaches 14.5% (ΔT = 420 K), which is quite high for a polycrystalline pristine material
〈Originals〉Relation between low take-off of the left atrial appendage and thromboembolic events in patients with atrial fibrillation : evaluation with multi-detector CT
[Abstract] The left atrial appendage (LA-Ap) is one of the major sources of cardiac thrombus formation responsible for thromboembolism inpatients with atrial fibrillation (AF). We hypothesized that the particular anatomical characteristics of the LA-Ap may facilitate thrombus formation. Methods : Seventy-four AF patients underwent transesophageal echocardiography (TEE) and multi-detector CT (MDCT) examinations. These patients were divided into two groups, with and without systemic embolism (Emb) [Emb (+) group, 10 patients, male/female =7/3 ; Emb (—) group, 64 patients, male/female = 51/13]. To evaluate the location of the LA-Ap in relation to the left atrium (LA), we determined four distinctive points on MDCT images using two carefully defined orthogonal sections : the superior summit of the mitral annulus (point-A), the anterior and posterior sites of the LA-Ap orifice (point-B and C), and the posterior LA (point-D). Next, we evaluated the relation of the geometrical intervals (A-B, B-C, C-D) to the prior thromboembolism. Results : Using multivariate analysis, a shorter A-B interval was recognized as an independent factor positively associated witha history of thromboembolism. Conclusion : The position of the LA-Ap orifice may affect the hemodynamic state of the LA-Ap, and anterior deviation of the LA-Ap orifice (low take-off of the LA-Ap) may be a risk factor for thrombus formation in LA-Ap and systemic embolism
A Gas Giant Planet in the OGLE-2006-BLG-284L Stellar Binary System
We present the analysis of microlensing event OGLE-2006-BLG-284, which has a
lens system that consists of two stars and a gas giant planet with a mass ratio
of to the primary. The mass ratio of the
two stars is , and their projected separation is AU, while the projected separation of the planet from the primary
is AU. For this lens system to have stable orbits, the
three-dimensional separation of either the primary and secondary stars or the
planet and primary star must be much larger than that these projected
separations. Since we do not know which is the case, the system could include
either a circumbinary or a circumstellar planet. Because there is no
measurement of the microlensing parallax effect or lens system brightness, we
can only make a rough Bayesian estimate of the lens system masses and
brightness. We find host star and planet masses of , , and
, and the -band magnitude of the combined
brightness of the host stars is . The separation
between the lens and source system will be mas in mid-2020, so it
should be possible to detect the host system with follow-up adaptive optics or
Hubble Space Telescope observations
A Gas Giant Planet in the OGLE-2006-BLG-284L Stellar Binary System
We present the analysis of microlensing event OGLE-2006-BLG-284, which has a lens system that consists of two stars and a gas giant planet with a mass ratio of q_p = (1.26 ± 0.19) × 10⁻³ to the primary. The mass ratio of the two stars is q_s = 0.289 ± 0.011, and their projected separation is s_s = 2.1 ± 0.7 au, while the projected separation of the planet from the primary is s_p = 2.2 ± 0.8 au. For this lens system to have stable orbits, the three-dimensional separation of either the primary and secondary stars or the planet and primary star must be much larger than the projected separations. Since we do not know which is the case, the system could include either a circumbinary or a circumstellar planet. Because there is no measurement of the microlensing parallax effect or lens system brightness, we can only make a rough Bayesian estimate of the lens system masses and brightness. We find host star and planet masses of, M_(L1) = 0.35^(+0.30)_(−0.20) M⊙, M_(L2) = 0.10^(+0.09)_(−0.06) M⊙, and m_p = 144^(+126)_(−82) M⊕, and the K-band magnitude of the combined brightness of the host stars is K_L = 19.7^(+0.7)_(−1.0). The separation between the lens and source system will be ~90 mas in mid-2020, so it should be possible to detect the host system with follow-up adaptive optics or Hubble Space Telescope observations
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