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21.
超子中子星性质的温度效应 总被引:2,自引:0,他引:2
从相对论平均场理论出发,考虑核子、超子和介子的相互作用,研究了温度对中子星组成粒子、状态方程和中子星质量等的影响.发现温度越高,超子在中子星内部出现时的重子数密度越低.当密度较高时,中子星的核心区主要由超子组成,即中子星转变成以奇异粒子为主要成分的超子星,并且这种转变受到温度的影响,温度越高,转变密度越低.由于超子的出现,中子星核心高密度区域的状态方程,对于不同温度,差别不大,所以有限温度中子星的最大质量都在1.8M⊙附近.这与观测结果相符. 相似文献
22.
简要叙述了稠密等离子体聚焦装置作为中子发生器的工作原理,对影响稠密等离子体聚焦装置放电出中子产额及其稳定性的一些因素和改进措施进行了简单讨论.通过使用不同电极形状的场畸变开关很好地提高了焦点装置的运行,使装置输出中子的起伏得到明显的改善.通过对腔内电极的清洁,在不更换气体的条件下,聚焦装置放电出中子产额稳定.The principle of dense plasma focus(DPF) as neutron generator has been investigated in this paper. We have stated briefly some factors that mainly influnce the DPF s neutron yield and some methods improving the stability of neutron yields on the dense plasma focus. It is showed that the fluctuation of DPF output neutron becomes smaller by using different types of field-distortion elements. Over 100 consecutive shots without purging the test gas the neutron yields has no obvious change. 相似文献
23.
This note investigates two long-standing conjectures on the Krull dimension of integer-valued polynomial rings and of polynomial rings in the context of (locally) essential domains.
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25.
Keka Chakraborty S K Paranjpe V Siruguri O D Jayakumar S K Kulshreshtha 《Pramana》1997,48(6):1115-1122
Neutron diffraction and M?ssbauer measurements have been carried out on the cubic Laves phase intermetallic TbMnFe. The magnetic
moment on the transition metal atom is found to be low, 0.2μ
B, at room temperature. This moment is temperature independent down to 10 K. Magnetic moment on the rare earth atom varies
from 2.5μ
B at 296 K to 7.27μ
B at 10 K. M?ssbauer spectra recorded at 298 K and 78 K have magnetic character but there is a large distribution of hyperfine
field values. Both these features arise due to magnetic frustration created in the sample due to the competing ferro and antiferromagnetic
interactions between the transition metal atoms. 相似文献
26.
Y. D. Kolekar S. B. Kulkarni Keka Chakraborty A. Das S. K. Paranjpe P. B. Joshi 《Pramana》2004,63(2):189-197
Nd2Sn2O7 pyrochlores with the substitution of Zr4+ were prepared by conventional ceramic double sintering technique. The single-phase formation was confirmed by X-ray diffraction
and neutron diffraction techniques. Relative intensity calculations for X-ray diffraction analysis were performed for oxygen
positional parametersx = 0.331 and 0.375, while Rietveld refinements were employed for neutron diffraction data. The neutron diffraction study revealed
that there are only two anion sites with 48f and 8b positions. This indicates that the 8a site, i.e. O(3) sublattice, is completely
vacant and the structure is a perfect cubic pyrochlore with space group Fd3m (O
h
7
). From the conductivity measurements, it is observed that the electronic conductivity dominates from room temperature up
to about 525 K and forT > 525 K, the oxygen ion conduction dominates the charge transport in these compositions. Complex impedance spectroscopy indicates
the existence of grain and grain boundary as two separate elements. 相似文献
27.
Yozo Miura Hiroyuki Dote Hiroyuki Kubonishi Kenichi Fukuda Tomoko Saka 《Journal of polymer science. Part A, Polymer chemistry》2007,45(6):1159-1169
A dendritic macroinitiator having 16 TEMPO‐based alkoxyamines, Star‐16 , was prepared by the reaction of a dendritic macroinitiator having eight TEMPO‐based alkoxyamines, [G‐3]‐OH , with 4,4′‐bis(chlorocarbonyl)biphenyl. The nitroxide‐mediated radical polymerization (NMRP) of styrene (St) from Star‐16 gave 16‐arm star polymers with PDI of 1.19–1.47, and NMPR of 4‐vinylpyridine from the 16‐arm star polymer gave 16‐arm star diblock copolymers with PDI of 1.30–1.43. The ring‐opening polymerization of ε‐caprolactone from [G‐3]‐OH and the subsequent NMRP of St gave AB8 9‐miktoarm star copolymers with PDI of 1.30–1.38. The benzyl ether linkages of the 16‐arm star polymers and the AB8 9‐miktoarm star copolymers were cleaved by treating with Me3SiI, and the resultant poly(St) arms were investigated by size exclusion chromatography (SEC). The SEC results showed PDIs of 1.23–1.28 and 1.18–1.22 for the star polymers and miktoarm stars copolymers, respectively, showing that they have well‐controlled poly(St) arms. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1159–1169, 2007. 相似文献
28.
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Small‐Angle Neutron Scattering has been performed from poly(ethylene oxide) in deuterated water at temperature ranging from 10 to 80 °C. A simple fitting model was used to obtain a correlation length and a Porod exponent. The correlation length L characterizes the average distance between entanglements in the semidilute region and is proportional to the individual coil sizes in the dilute region. L was found to increase with temperature in the semidilute region but it decreases with temperature in the dilute region. This decrease is the precursor to the single‐chain collapse which applies to very dilute polymer solutions. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 2196–2200, 2007 相似文献
30.