A study of the suppression of the high-temperature helium embrittlement in an oxide-particle dispersion strengthened alloy

In this paper, an investigation on the micro-structure of an Fe-base oxide-dispersion-strengthened (ODS) alloy irradiated with high-energy Ne-20 ions to different doses at a temperature around 0.5T(m) (T-m is the melting point of the alloy) is presented. Investigation with the transmission electron microscopy found that the accelerated growth of voids at grain-boundaries, which is usually a concern in conventional Fe-base alloys under conditions of inert-gas implantation, was not observed in the ODS alloy irradiated even to the highest dose (12000 at.ppm Ne). The reason is ascribed to the enhanced recombination of point defects and strong trapping of Ne atoms at the interfaces of the nano-scale oxide particles in grains. The study showed that ODS alloys have good resistance to the high-temperature inter-granular embrittlement due to inert-gas accumulation, exhibiting prominence of application in harsh situations of considerable helium production at elevated temperatures like in a fusion reactor.

Angular dispersion and deflection function for heavy ion elastic scattering

The differential cross sections for elastic scattering products of F-17 on Pb-208 have been measured. The angular dispersion plots of ln(d sigma/d theta) versus theta(2) are obtained from the angular distribution of the elastic scattering differential cross sections. Systematical analysis on the angular dispersion for the available experimental data indicates that there is an angular dispersion turning angle at forward angular range within the grazing angle. This turning angle can be clarified as nuclear rainbow in classical deflection function. The exotic behaviour of the nuclear rainbow angle offers a new probe to investigate the halo and skin phenomena.

Elastic scattering angular dispersion of weakly bound nucleus F-17

The differential cross-sections for elastic scattering of F-17 and O-17 on Pb-208 have been measured at Radioactive Ion Beam Line at Lanzhou (RIBLL). The variation of the logarithms of differential cross-sections with the square of scattering angles, viz. angulax dispersion plot, shows clearly that there exists a turning point in the range of small scattering angles (6 degrees-20 degrees) for F-17 due to its exotic structure, while no turning point was observed for O-17. The experimental results have been compared with previous data of other groups. Systematical analysis on the available data seems to conclude that there is an exotic behavior of elastic scattering angular dispersion of weakly bound nuclei with halo or skin structure as compared with that of the stable nuclei. Therefore the fact that the turning point of the elastic scattering angular dispersion plot appears at small angle for weakly bound nuclei can be used as a new probe to investigate the halo and skin phenomenon.

Exotic behaviour of angular dispersion of weakly bound nucleus F-17 at small angles

The differential cross sections of F-17 and O-17 elastic scattering products on Pb-208 have been measured at the Radioactive Ion Beam Line at Lanzhou (RIBLL). Two angular dispersion plots of ln(d sigma/d theta) versus theta 2 are obtained from the angular distribution of the elastic scattering differential cross sections. The angular dispersion plot exhibits a clear turning point for F-17 in the range of small scattering angles 6 degrees-20 degrees due to its exotic structure, but for O-17, the turning point is not observed in the same angular range. The experimental results have been compared with previous data of other groups. Systematical analysis on the available data supports the above conclusion that there is an exotic behaviour of the angular dispersion plot of weakly bound nuclei with halo or skin structure as compared with that of the ordinary nuclei near stable line. Therefore the turning point of the angular dispersion plot appears at small angle for weakly bound nuclei with halo or skin structure, and can be used as a new probe to investigate the halo and skin phenomena of weakly bound nuclei.

Multi-phonon gamma-vibrational bands in odd-mass nuclei studied by triaxial projected shell model approach

Inspired by the recent experimental data [J.-G. Wang, et al., Phys. Lett. B 675 (2009) 420], we extend the triaxial projected shell model approach to study the gamma-band structure in odd-mass nuclei. As a first application of the new development, the gamma-vibrational structure of Nb-103 is investigated. It is demonstrated that the model describes the ground-state band and multi-phonon gamma-vibrations quite satisfactorily, supporting the interpretation of the data as one of the few experimentally-known examples of simultaneous occurrence of one- and two-gamma-phonon vibrational bands. This generalizes the well-known concept of the surface gamma-oscillation in deformed nuclei built on the ground-state in even-even systems to gamma-bands based on quasiparticle configurations in odd-mass systems. (c) 2010 Elsevier BM. All rights reserved.

Determination and identification of isoflavonoids in Radix astragali by matrix solid-phase dispersion extraction and high-performance liquid chromatography with photodiode array and mass spectrometric detection

The isoflavonoids in Radix astragali were determined and identified by HPLC-photodiode array detection-MS after extraction employing matrix solid-phase dispersion (MSPD). As a new sample preparation method for R. astragali, the MSPD procedure was optimized, validated and compared with conventional methods including ultrasonic and Soxhlet extraction. The amounts of two major components in this herb, formononetin (6) and ononin (2), were determined based on their authentic standards. Four major isoflavonoids, formononetin (6), ononin (2), calycosin (5) and its glycoside (1), and three minor isoflavonoids, (6aR,11aR)-3-hydroxy-9, 10-dimethoxypterocarpan (7), its glycoside (3), and (3R)-7,2'-dihydroxy-3',4'-dimethoxyisoflavone-7-O-beta-D-glycoside (4), were identified based on their characteristic two-band UV spectra and [M + H](+), [aglycone + H](+) and [A1 + H](+) ions, etc. The combined MSPD and HPLC-DAD-MS method was suitable for quantitative and qualitative determination of the isoflavonoids in R. astragali. (C) 2003 Elsevier B.V. All rights reserved.

Blue electroluminescent polymers with dopant-host systems and molecular dispersion features: polyfluorene as the deep blue host and 1,8-naphthalimide derivative units as the light blue dopants

We developed a series of highly efficient blue electroluminescent polymers with dopant-host systems and molecular dispersion features by selecting 1,8-naphthalimide derivatives as the light blue emissive dopant units, choosing polyfluorene as the deep blue emissive polymer host and covalently attaching the dopant units to the side chain of the polymer host. The polymers' EL spectra exhibited both deep blue emission from the polymer host and light blue emission from the dopant units because of the energy transfer and charge trapping from the polymer host to the dopant units.

Highly efficient red electroluminescent polymers with dopant/host system and molecular dispersion feature: polyfluorene as the host and 2,1,3-benzothiadiazole derivatives as the red dopant

By selecting polyfluorene as the polymer host, choosing 2,1,3-benzothiadiazole derivative moieties as the red dopant units and covalently attaching 0.3 mol% of the dopant units to the side chain of the polymer host, we developed a novel series of red electroluminescent polymers of dopant/host system with molecular dispersion feature. Their EL spectra exhibited predominant red emission from the dopant units because of the energy transfer and charge trapping from the polymer backbone to the dopant units. The emission wavelength of the polymers could be tuned by modifying the chemical structures of the dopant units.

Conducting polyaniline film from aqueous dispersion: Crystallizable side chain forced lamellar structure for high conductivity

Aqueous conducting polyaniline dispersion was prepared employing acidic phosphate ester bearing hydrophilic ethylene glycol segment as dopant, and conducting film with electrical conductivity of 25 S/cm was obtained from the dispersion. Ordered self-assembly lamellar structure with interlamellar distance of 1.2 nm was observed in the film, which consisted of alternating layers of rigid polyaniline chain and flexible phosphate ester side chains, where the phosphate side chain layer was separated by two rigid polyaniline layers. The lamellar structure leading to high conducting film was formed due to the confinement of polyaniline chain by crystallizable phosphate side chain, since the electrical conductivity decreased by four orders of magnitude once the dopant side chain crystalline was destroyed. The crystallizable side chain forced lamellar structure is expected to be a new chance for highly conducting polyaniline.

Individual dispersion of synthetic imogolite nanotubes via droplet evaporation

Morphology of synthetic imogolite nanotubes formed in droplet evaporation was investigated by transmission electron microscopy and electron diffraction. The nanotubes form a dense entangled network at higher concentrations, while at lower concentrations the nanotubes are liable to form oriented bundles. Under enthanol atmosphere, individual dispersion of nanotubes was observed for the first time, which reveals the length polydispersity of synthetic imogolite nanotubes.

An investigation on the dispersion of montmorillonite (MMT) primary particles in PP matrix

A novel path of preparing PP/o-MMT nanocomposites, which pay attention to the breaking up of MMT original agglomerates and dispersing of its primary particles, rather than the intercalation or exfoliation degree of o-MMT, was reported. The method of predispersing the o-MMT particles into a polar poly(vinyl alcohol) (PVA) matrix and then melt blending the pre-treated PVA/o-MMT hybrids with PP was studied. 3-isopropenyl-alpha,alpha-dimethylbenzene-isocyanate (TMI) was used as a modifier of PVA to improve the compatibility between PVA and PP matrix. Pre-disperse o-MMT with TMI modified PVA was proved to be an effective way to get a composite with fine o-MMT particles dispersion. But the method, which is pre-dispersing o-MMT with non modified PVA and then using TMI to modify such PVA/o-MMT hybrid, would largely reduce the reaction degree between TMI and PVA because of the relatively lower reaction temperature. Although the latter method also can obtain finer dispersion composites than that with using PP-g-MAH as compatibilizer, the relatively higher degradation degree of PP matrix in this method will limit the use of this nanocomposite.