Air vent in water chamber and surface coating on liner slides concerning auxiliary cooling system for the high temperature engineering test reactor

Experimental study was made to confirm the validity of new designs of the auxiliary cooling system for the high temperature engineering test reactor (HTTR). First, it is necessary to vent residence air in outlet side of water chamber of the auxiliary heat exchanger for the HTTR. Accordingly, we have proposed to mount a proper bend duct in the outlet side of the water chamber. Air vent is done by difference between pressures at both ends of the bend duct caused by the forced water circulation using the water pumps. From flow tests, it was confirmed that it is capable of venting the air through the bend duct by circulating the water in maximum capacity of the water pumps. Second, it is essential to prevent seizure and excessive wear of the liner slides of the auxiliary concentric hot gas duct for the HTTR at a service temperature of 950°C. Therefore, we have put forward to coat titanium nitride (TiN) on the surface of the liner slides made of nickel-based superalloy Hastelloy XR using the thermochemical vapor deposition method. As a result of seizure and wear tests, it was confirmed that the TiN coating film of 3 μm on the surface of Hastelloy XR is sufficient.     

The generalized boundary element approach to Burgers' equation

The generalized boundary element method is presented for the numerical solution of Burgers' equation. The new method is based on the set of boundary integral equations derived for each subdomain by using the fundamental solution for the linearized differential operator of the equation. The resulting system of quasi-non-linear equations is solved implicitly with use of a simple iterative procedure. The adaptability and the accuracy of the proposed method are demonstrated by three examples and a comparison of the numerical results with the exact solution or other existing solutions is shown for the first example.     

Ti-Containing Silsesquioxane Gels with Tunable Porosity: Preparation and Catalytic Activity for the Epoxidation of Cyclooctene by Aqueous Hydrogen Peroxide

Novel Ti-containing silsesquioxane gel catalysts were prepared by the hydrosilylative condensation of Ti-containing silsesquioxanes together with cubic silsesquioxanes and spherosilicates. The porosity of gels was controlled by changing the composition and the mixing order of the starting materials. Both porous and nonporous gels were found to act as excellent heterogeneous catalysts towards the selective epoxidation of cyclooctene by the use of aqueous hydrogen peroxide as an oxidant.     

Elastic basket switching

This paper proposes a new integrated switching system, ‘elastic basket switching’, for broadband and multimedia communications, including voice and high-speed data. In elastic basket switching (EBS), it is possible flexibly and efficiently to handle multimedia information by adaptively assigning communication resources according to communication requests and bandwidth of switched information. For continuous information, such as voice, EBS functions just as a circuit switching system, and for burst data it achieves high-efficiency bandwidth usage equivalent to a packet switching system by demand-assign type time-slot assignment. The detail of EBS and its application to a departmental system-orientated PBX are described. The traffic handling capability and details of the hardware structure are presented. The experimental system, including use of LSIs in the main parts of EBS is also described.     

Development of a micro total analysis system incorporating chemiluminescence detection and application to detection of cancer markers

We developed a micro total analysis system (mu-TAS) incorporating chemiluminescence detection, in which the chemiluminescence reaction of isoluminol isothiocyanato (ILITC) (as a chemiluminescence reagent for labeling)-microperoxidase (as a catalyst)-hydrogen peroxide (as an oxidant) was adopted. The analysis system performed the following three processes on a microchip: immune reaction for high selectivity, electrophoresis for formation and transportation of the sample plug, and chemiluminescence detection for high sensitivity. The three processes were compactly integrated onto the microchip to give the mu-TAS. The microchip contained two microchannels that crossed at an intersection, while the ends of the microchannels accessed four reservoirs. As the first process, the immune reaction was performed using an antibody-immobilized glass bead. The glass bead was placed in one of the reservoirs along with antigen (analyte) and a known amount of ILITC-labeled antigen to set up a competitive immune reaction. For electrophoresis, as the second process, the reactant after the immune reaction was fed electrophoretically into the intersection resulting in a sample plug. The sample plug was then moved into another reservoir containing hydrogen peroxide solution. At this point, chemiluminescence detection was performed as the third process: the labeled antigen mixed with the hydrogen peroxide and the catalyst included in the migration buffer to produce chemiluminescence. Chemiluminescence was detected by a photomultiplier tube located under the reservoir. The mu-TAS described here was capable of determining, with high selectivity and sensitivity, human serum albumin or immunosuppressive acidic protein as a cancer marker in human serum.     

Kinetic study of thermostable L-threonine dehydrogenase from an archaeon Pyrococcus horikoshii

In the genome data base of the hyperthermophilic archaeon Pyrococcus horikoshii, an open reading frame with sequence homology to a gene encoding alcohol dehydrogenase was found. It was demonstrated that the encoded enzyme was a thermostable L-threonine dehydrogenase which can oxidize the hydroxy alkyl residue of L-threonine associated with the reduction of NAD+ or NADP+. This enzyme is a member of the zinc-containing L-threonine dehydrogenase family. One enzyme molecule contained one zinc atom, and this metal was considered to contribute to the hyperthermostablility of the enzyme. The reaction of the enzyme proceeded via a sequential mechanism. The Michaelis constants (Km) for L-threonine and NAD+ were 0.013 and 0.010 mM, respectively, and the maximum reaction rate (Vmax) was 1.75 mmol NADH formed/min/mg-protein at 65 degrees C. The Km values for both L-threonine and NADP+ were larger than those for L-threonine and NAD+ with a similar Vmax value. These results indicate that the enzyme has lower affinity to NADP+ than to NAD+, and the binding affinity for L-threonine depends on the coenzymes.