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A new physical scheme for femtosecond X-ray lasers, where the upper lasing is pumped by X-ray photons and the lower lasing level is depopulated via a Coster-Kronig radiationless transition, is analyzed for Ca. The transition wavelength is 4.1 nm, which is inside the water window. The peak spectral brightness of the X-ray laser output at 4.1 nm is predicted to be as large as 5 x l025photons/sec./(mm2mrad20.1% bandwidth), which is 4 to 5 orders of magnitude brighter than a typical undulator radiation in the similar spectral region. In addition to the high flux, the expected duration of X-ray lasing of ~ 3 fs. will be useful for the study of fast dynamics in physical and biological sciences.

AbstractOne of the main missions of KSTAR is to develop long-pulse operation capability relevant to the production of fusion energy. After a full metal wall configuration was decided for ITER, a major upgrade for KSTAR was planned, to a tungsten first wall similar to the JET ITER-like wall (coatings and bulk tungsten plasma-facing components). To accomplish the upgrade, tungsten bonding technology has been developed and tested. Since the leading edges of each castellation structure have to be protected, shaping of tungsten blocks has been studied by ANSYS simulation, and the miniaturized castellation has been exposed to Ohmic plasma to confirm the simulation results. It is found that a shaped castellation block has more heat handling capability than a conventional block. For more dedicated experiments, a multipurpose castellation block is fabricated and exposed to Ohmic, L- and H-mode plasmas and observed by IR camera from the top. During the fabrication and assembly of the blocks, leading edges caused by “naturally misaligned” blocks due to engineering limits with a maximum level up to 0.5 mm have been observed, and these have to be minimized for the future fusion machine.

AbstractThe tritium metering, assay, recovery and storage (TriMARS) facility of KEPCO Research Institute has been installed to develop expertise in the tritium handling technology and to support the tritium control system in Korea. The major systems and equipment of the facility consisted of a tritium assaying and dispensing system, a tritium recovery system, a purge gas recombiner system, a tritium calorimeter, a gas chromatograph, tritium monitors, a high integrity glove box and air purged enclosures. The annual tritium usage is restricted below 11.5 PBq of tritium. The tritium dispensing and loading would be carried out by batch transfers. Tritium metering is based on accurate pressure-volume-temperature measurements and GC analysis. Three metering tanks were provided to measure 0.37 TBq to 185 TBq of T2gas at sub-atmospheric pressure. Three uranium beds were installed to store tritium from outside and to recover the tritium residual of process equipment in the facility. Tritium recovery systems, secondary enclosures and tritium monitors were provided to protect workers from tritium exposure. For tritium accountancy for all shipments in and out at the facility, a dedicated twin cell tritium calorimeter was installed and demonstrated.

The continuously variable damper is widely used in the semi-active suspension system since it can yield various damping forces at a given damper velocity. By applying an appropriate control scheme to the damper, satisfaction of both ride comfort and driving safety can be realised. For successful development of the semi-active suspension system, a model that accurately describes the complex and nonlinear behaviour of the continuously variable damper is crucial. In this research, a modelling technique for the continuously variable damper has been studied. Various damper components have been analysed and their effects upon damper characteristics have been closely investigated. The effects of the damper characteristics change upon ride comfort and driving safety have also been investigated via simulations.

Abstract:  A novel type of bioreactor was successfully developed for the production of taxol and its precursors by culturing cells of Taxus cuspidata (Japanese yew) on a pilot-scale. Rapidly growing cell lines were selected from callus cultures derived from immature embryos of yew. The cells were inoculated in 20-l capacity bioreactors of different types to test the growth performance. The models of small-scale bioreactors incorporated in this study included a balloon-type bubble bioreactor (BTBB), a bubble-column bioreactor (BCB), a BCB with a split-plate internal loop, a BCB with a concentric draught-tube internal loop, a BCB with a fluidized bed bioreactor, and two different models of stirred tank reactors. Among the reactors, BTBB appeared to be the most efficient in promoting cell growth. The doubling time of cell growth in BTBB was 12 days with a 30% inoculation cell density. The optimum time for medium replacement or feeding was 12–15 days after inoculation as determined by monitoring both the levels of sugars and medium conductivity. When yew tree cells were grown in different sizes (100–500-l) of BTBBs, more than 70% cell viability was recorded at the time of harvest. The growth pattern of the cells in the pilot-scale BTBB appeared to be the same as that of cells in the 20-l bioreactors. Approximately 3 mg/l of taxol and 74 mg/l total taxanes were obtained after 27 days of culture.

In order to describe the degree of interaction of a molecule with its environments by descriptors, several three-dimensional descriptors have been proposed. With the physical properties calculated around a molecule, scalar, vector, and tensor (zeroth, first, and second moments) of the physical properties were calculated and were used as descriptors for calculating the similarity index between the molecules. The tensors contain the information on the spatial distribution of those physical properties around the molecule. Hydration Free Energy Density (HFED) proposed by No et al. was used to calculate HFED tensor. The descriptors were used for the similarity index calculations between substituted benzenes and between lead compounds of HIV-1 protease inhibitors. The substituted benzenes are grouped according to the similarity indices. The grouping seems reasonable from the viewpoint of a chemical sense. The lead fragments of the HIV-1 protease inhibitors have a high similarity among themselves though their chemical formulas are not very similar, the lead fragments are diverse. Although the chemical formulas are diverse, the spatial distribution of the physical properties around the molecules is similar. The descriptors have high discriminating power in the similarity calculation between the molecules.

1,1‐Diphenylethylene (Ia) undergoes radical‐induced dimerization in the presence of aminium hexachloroantimonates to give the indan (II).