Atomic motion of guest atoms inside semiconducting clathrate cages is considered an important source for glasslike thermal behavior. 69Ga and 71Ga nuclear magnetic resonance studies on type I Ba8Ga16Sn30 show a clear ...
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Atomic motion of guest atoms inside semiconducting clathrate cages is considered an important source for glasslike thermal behavior. 69Ga and 71Ga nuclear magnetic resonance studies on type I Ba8Ga16Sn30 show a clear low-temperature relaxation peak attributed to the influence of Ba rattling dynamics on the framework-atom resonance, with a quadrupolar relaxation mechanism as the leading contribution. Data are analyzed using a two-phonon Raman process, according to a recent theory involving localized anharmonic oscillators. Excellent agreement is obtained using this model, with the parameters corresponding to a uniform array of localized oscillators with very large anharmonicity.
We have developed a microfluidic reactor array enabling systematic assessment of bacterial cells in a batch culture condition. This system enables creating a series of different growth conditions by preserving differe...
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ISBN:
(纸本)9781618395955
We have developed a microfluidic reactor array enabling systematic assessment of bacterial cells in a batch culture condition. This system enables creating a series of different growth conditions by preserving different growth factors inside nanoliter reactors and cultivating bacterial cells inside the reactors. From a single on-chip experiment, we determined the effects of carbon sources on bacterial phenotypes, i.e. the pattern of growth curves with Escherichia coli K-12. We demonstrated the systematic assessment of inhibition effect of antibiotics on the growth of Pseudomonas aeruginosa. The present system could be used for systematic phenotypic study of different types of bacterial cells.
A divacancy (DV) is one of the most abundant and most important defects in irradiated graphene, which modifies electronic and chemical properties of graphene. In this paper, we present ab initio calculations to study ...
A divacancy (DV) is one of the most abundant and most important defects in irradiated graphene, which modifies electronic and chemical properties of graphene. In this paper, we present ab initio calculations to study the dynamics and stability of DVs in graphene. Divacancies in graphene have various reconstructed structures, such as triple pentagon-triple heptagon (555-777) and pentagon-octagon-pentagon (5-8-5) patterns. A direct observation of the structural transformations between these reconstructions was recorded in transmission electron microscope images reported by Girit et al. in science 323, 1705 (2009). We clarify the atomic structures of DVs observed in the experiment and investigate the atomic processes and energetics for the observed dynamical motions in great detail. It is found that a series of Stone–Wales-type transformations are responsible for the migration and structural transformations of DVs and that a pentagon-heptagon-heptagon-pentagon (5-7-7-5) defect appearing as an intermediate structure during the dynamical process plays an important role in the transformations of DVs.
We report results of the study of the low-frequency noise in thin films of bismuth selenide topological insulators, which were mechanically exfoliated from bulk crystals via “graphene-like” procedures. From the resi...
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We report results of the study of the low-frequency noise in thin films of bismuth selenide topological insulators, which were mechanically exfoliated from bulk crystals via “graphene-like” procedures. From the resistance dependence on the film thickness, it was established that the surface conduction contributions to electron transport were dominant. It was found that the current fluctuations have the noise spectral density SI ∞ 1/ f (where f is the frequency) for the frequency range up to 10 kHz. The obtained noise data are important for transport experiments with topological insulators and for any proposed device applications of these materials.
Natural and synthetic hydroxyapatite (HA) scaffolds for potential load-bearing bone implants were fabricated by two methods. The natural scaffolds were formed by heating bovine cancellous bone at 1325°C, which re...
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Natural and synthetic hydroxyapatite (HA) scaffolds for potential load-bearing bone implants were fabricated by two methods. The natural scaffolds were formed by heating bovine cancellous bone at 1325°C, which removed the organic and sintered the HA. The synthetic scaffolds were prepared by freeze-casting HA powders, using different solid loadings (20–35 vol.%) and cooling rates (1–10°C/min). Both types of scaffolds were infiltrated with polymethylmethacrylate (PMMA). The porosity, pore size, and compressive mechanical properties of the natural and synthetic scaffolds were investigated and compared to that of natural cortical and cancellous bone. Prior to infiltration, the sintered cancellous scaffolds exhibited pore sizes of 100–300 μm, a strength of 0.4–9.7 MPa, and a Young’s modulus of 0.1–1.2 GPa. The freeze-casted scaffolds had pore sizes of 10–50 μm, strengths of 0.7–95.1 MPa, and Young’s moduli of 0.1–19.2 GPa. When infiltrated with PMMA, the cancellous bone- PMMA composite showed a strength of 55 MPa and a Young’s modulus of 4.5 GPa. Preliminary data for the synthetic HA-PMMA composite showed a strength of 42 MPa and a modulus of 0.8 GPa.
Single crystal SmMnO3 has been grown by the floating-zone method. We have measured the magnetization and specific heat in magnetic fields oriented along three principal crystal axes of precisely oriented single crysta...
Single crystal SmMnO3 has been grown by the floating-zone method. We have measured the magnetization and specific heat in magnetic fields oriented along three principal crystal axes of precisely oriented single crystals. Below TN of the Mn3+-ion array, the magnetic moments of the Sm3+ ions are progressively oriented antiparellel to the weak canted-spin ferromagnetic moment of the antiferromagnetic (AF) Mn3+-ion array due to an internal exchange field Hin ∥ c. On cooling through a compensation temperature Tcomp ≈ 9 K, the dominant moment parallel to c changes from the canted-spin Mn3+ ions to the Sm3+ moments. A spin reversal in an Hc ≥ 1 T changes the magnetic field splitting of the Kramers doublet on the Sm3+ ions from Hin − Hc to Hin + Hc, where Hc is a field applied along the c axis. This change, monitored by the Schottky contribution to the specific heat, creates an abrupt change at Tt = Tcomp ± δ. We have found no evidence that the transition at Tt is first-order despite its abrupt nature.
We report on multilayered optical storage in Sm(DBM)2Phen-doped and un-doped polymethylmethacrylate read out by fluorescence and reflection modes. The detection of fluorescence signal enables retrieval of the stored b...
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