[en] The 100MeV Linac proton accelerator is planned to be built at Gyungju, Korea by 2012 and a future upgrade of the facility can be considered. For maximizing the utilization of the PEFP accelerator, the following studies on spallation neutron facility and its scientific applications were performed: (i) Introduction and discussion of spallation neutron sciences through oragnization of a neutron session in The 13ICABU conference and organization of the 1st workshop on the development of spallation neutron source using the proton accelerator and its spectrometers, (ii) networking the experts abroad, (iii) the flux history of accelerator-based (spallation) neutron sources and reactor-based (continuous) neutron sources, (v) the features and spectrometers of spallation neutron sources, (vi) discussion on upgrade of the 100MeV PEFP accelerator

[en] Pt nanoparticles dispersed on ceramic powder such as alumina and ceria powder are used as catalyst materials to reduce pollution from automobile exhaust, power plant exhaust, etc. Much effort has been put to investigate the relationship between types of catalyst support materials and reactivity of the supported metallic particles. The surface shape of support materials can also be expected to control the catalysts size with the surface shape of support materials. In this presentation, we show our SANS (small angle neutron scattering) -USANS (ultra small angle neutron scattering) analysis on the structural differences of different shapes of the same γ alumina powder with different loadings of Pt nanoparticles. Then, the reactivity of the prepared catalyst materials are presented and discussed based on the investigation of the structure of the support materials by SANS. The shapes of gamma alumina, rod-like or plate-like shape, were determined from nanometer to micrometer with USANS and SANS analysis. We found that the platelet-like alumina consists of an aggregate of 2 - 3 layers, which further reduce specific surface area and catalytic activity compared to rod-like shape. Rod-like shape shows more than 100% enhancement in the catalytic activities in model three-way-catalyst (TWC) reactions of CO, NO, and C_3H_6 at low temperature around 200 .deg. C

[en] Full text: As part of a wider study into high internal phase emulsions, we have prepared and studied by SANS and USANS the structure of an unstable emulsion consisting of 90% by volume saturated ammonium nitrate dispersed as micron-scale droplets in hexadecane, stabilised by the surfactant Pluronic L92. Similar emulsions produced using polyisobutylene-based surfactants, reported earlier, are highly stabilised by a significant number of surfactant rich reverse micelles a few nanometres in diameter in the oil phase. The aqueous-oil droplet interfaces are coated with a monolayer of surfactant, while a very small amount of surfactant is aggregated into micron-scale surfactant-rich objects. In contrast, the Pluronic emulsion contains insignificant numbers of reverse micelles and a complex multilayered interface between oil and aqueous phases. Now, the great majority of added surfactant is in the form of micron scale, fractally linked, blocks of lamellar phase at the aqueous-oil droplet interfaces. The lamellar phase can be characterised by the Bragg peaks observed in three different isotopic contrasts by SANS. We attribute the shear instability of the Pluronic emulsion to the more hydrophilic nature of the surfactant which causes both depletion of reverse micelles in the oil phase, and aggregation into the blocks of lamellar phase. (authors)

[en] The structure of porous TiO₂ prepared by electrochemical anodization in a fluoride-containing ethylene glycol electrolyte solution was quantitatively studied using small-angle neutron scattering (SANS) and ultra-small-angle neutron scattering (USANS). The cylindrical pores along the coaxial direction were somewhat irregular in shape, were widely distributed in diameter, and seemed to have a broadly pseudo-hexagonal arrangement. The scattering from the pore wall showed a negative deviation from Porod scattering, indicating that the interface between TiO2 and the pore was not sharp. A density gradient of around 40-60 A at the pore wall (i.e. the interface between the pore and the TiO₂ matrix) was estimated using both constant and semi-sigmoidal interface models. This gradient may be due to the presence of fluorine and carbon partially absorbed by the pore wall from the fluoride-containing electrolyte or to sorbed water molecules on the wall. The neutron contrast-matching point between the TiO₂ matrix and the pores filled with liquid H₂O/D₂O mixtures was 51/49%(v/v) H₂O/D₂O, yielding an estimated mass density of 3.32 g cm^-3. The specific surface area of the sample derived from the (U)SANS data was around 939-1003 m² cm^-3 (283-302 m² g^-1). (orig.)

[en] An in situ vapor sorption apparatus has been constructed for use in small-angle neutron scattering (SANS) measurements. The apparatus adapts two independent operating mechanisms, with and without a carrier gas, to control relative or absolute pressure, respectively, in the SANS sorption cell. By controlling the absolute pressure, a target relative vapor pressure between 0% and 90% can be reached within 1-2 min. The short response time makes it possible to correlate diffusion kinetics and/or sorption/desorption isotherms with structure evolution during wetting/drying, which is not possible in gravimetric methods. Also, one can extract diffusion coefficients and interaction parameters. Other uses include the enhancement of scattering contrast in the study of semicrystalline polymers by the preferential vapor sorption of deuterated vapor into the amorphous regions. Thus, one can obtain the same structural information as small-angle x-ray scattering measurements on dry samples. Also, the apparatus has the capability to inject a pore-masking liquid into the sample cell while under vacuum to ensure the filling of all open porosities in a sample. The capability to mix two vapors in various ratios facilitates the determination of a contrast-matching point using a single sample, which also eliminates a major source of systematic error. The performance of the apparatus is demonstrated using a polyelectrolyte membrane and semicrystalline polyethylene. Additionally, technical points relating to controlling the relative vapor pressure, relative humidity, and regarding the vapor distribution in the cell are discussed

[en] Various drug-eluting stents (DESs) have been developed to prevent restenosis after stent implantation. However, DES still needs to improve the drug-in-polymer coating stability and control of drug release for effective clinical treatment. In this study, the cobalt-chromium (Co−Cr) alloy surface was coated with biodegradable poly(D,L-lactide) (PDLLA) and sirolimus (SRL) mixed with hydrophilic Pluronic F127 additive by using ultrasonic spray coating system in order to achieve a stable coating surface and control SRL release. The degradation of PDLLA/SRL coating was studied under physiological solution. It was found that adding F127 reduced the degradation of PDLLA and improved the coating stability during 60 days. The effects of organic solvent such as chloroform and tetrahydrofuran (THF) on the coating uniformity were also examined. It was revealed that THF produced a very smooth and uniform coating compared to chloroform. The patterns of in vitro drug release according to the type of organic solvent and hydrophilic additive proposed the possibility of controllable drug release design in DES. It was found that using F127 the drug release was sustained regardless of the organic solvent used. In addition, THF was able to get faster and controlled release profile when compared to chloroform. The structure of SRL molecules in different organic solvents was investigated using ultra-small angle neutron scattering. Furthermore, the structure of SRL is concentration-dependent in chloroform with tight nature under high concentration, but concentration-independent in THF. These results strongly demonstrated that coating stability and drug release patterns can be changed by physicochemical properties of various parameters such as organic solvents, additive, and coating strategy. - Highlights: • The morphology of sirolimus coating layer was stable without irregularity or roughness under optimal coating conditions. • Sirolimus was sustained release from PDLLA coating layer coated on the stent. • A controllable drug release system was designed using different types of solvents and F127 additive. • The molecular size of sirolimus in THF was larger than that in chloroform. • Provide helpful information for understanding the sirolimus behavior in polymer solution based on organic solvents.