Experimental studies on the thermal and hydraulic performance of the fuel stack of the VHTR: Part II. HENDEL multi-channel test rig with twelve fuel rods

Tests on heat transfer and fluid-dynamics of the mock-up fuel stack of the Very High Temperature Gas Cooled Reactor (VHTR) were performed by the multi-channel test rig (T_{1 - M}) of the Helium Engineering Demonstration Loop (HENDEL). The T_{1 - M} simulated one column of the fuel stack in the VHTR core and contained twelve simulated fuel rods. The heat generation rate of each fuel rod was varied to simulate the power distribution of the VHTR core in the horizontal plane. In parallel with this experiment, a three-dimensional thermal analysis code was developed in order to check the experimental temperature distribution of the fuel stack.Experimental results showed that the distribution of the helium gas flow rate was influenced by the temperature distortion in the mock-up fuel stack. The maximum deviation of the helium gas flow rate from the mean value was 10% in the case of an asymmetric power distribution test at a low Reynolds number. The variation of the calculated temperature distribution in the fuel stack was about 17-35°C in each case, indicating that the temperature distortion in the fuel stack was flattened by thermal conduction in the graphite block.     

Transcriptional sequencing: A method for DNA sequencing using RNA polymerase

We have developed a sequencing method based on the RNA polymerase chain termination reaction with rhodamine dye attached to 3'-deoxynucleoside triphosphate (3'-dNTP). This method enables us to conduct a rapid isothermal sequencing reaction in <30 min, to reduce the amount of template required, and to do PCR direct sequencing without the elimination of primers and 2'-dNTP, which disturbs the Sanger sequencing reaction. An accurate and longer read length was made possible by newly designed four-color dye-3'-dNTPs and mutated RNA polymerase with an improved incorporation rate of 3'-dNTP. This method should be useful for large-scale sequencing in genome projects and clinical diagnosis.     

Polymer channel waveguides with low loss at 1.3 mu m

Highly transparent polymers in the 0.6-1.3 mu m wavelength region have been synthesised from deuterated or halogenated methacrylate monomers. Low loss waveguides of less than 0.1 dB/cm at a wavelength of 1.3 mu m have been fabricated using the polymers.<>     

Effect of Goreisan,a Japanese Traditional Medicine,on Cortical Spreading Depolarization in Mice

Goreisan, a traditional Japanese Kampo medicine, is often used to treat headaches, including migraines; however, the underlying mechanisms remain unknown. Therefore, we investigated whether chronic treatment with Goreisan affects cortical spreading depolarization (CSD) in migraines. CSD susceptibility was assessed in male and female C57BL/6 mice by comparing CSD threshold, propagation velocity, and CSD frequency between animals treated with Goreisan for approximately 3 weeks and the corresponding controls with a potassium-induced CSD model. No significant differences were observed in CSD susceptibility between mice that were chronically treated with Goreisan and the control mice. Additionally, no significant differences were observed in other physiological parameters, including body weight, blood gases, and blood pressure. CSD susceptibility was not affected by chronic treatment with Goreisan, which suggests that the drug treats headaches via mechanisms that do not involve CSD modulation.     

Growth and Characterization of Tl2Ba2CuOx(Tl-2201) Single Crystals

A new closed-atmosphere method using a gold crucible has been developed to grow single crystals of the Tl-based cuprate superconductors by a self-flux growth method. This new method can provide us mm-sized single crystals of Tl₂Ba₂CuO_x. It should be noted that the value in the resistivity ratio R(300K)/R(T_c) (RRR) of one of the as-grown crystals is 18.3. This high RRR value indicates that the newly developed method is useful to obtain extremely high-quality single crystals of Tl₂Ba₂CuO_x.     

An 80-ns 1-Mb flash memory with on-chip erase/erase-verifycontroller

An internal erase and erase-verify control system has been implemented in an electrically erasable, reprogrammable, 80-ns 1-Mb flash memory, which is suitable for in-system reprogram applications. The memory utilizes a one-transistor type cell with a cell area of 10.4 μ². The die area is 32.3 mm². An erase mode is initiated by a 50-ns pulse. An erase and erase-verify sequence is automatically conducted in a chip without any further external control. The internal status can be checked through a status-polling mode. The 80-ns access time results from advanced sense amplifiers as well as low-resistance polysilicide word lines and scaled periphery transistors. To realize high-sensitivity, high-speed sense circuits, a pMOS transistor (whose gate is connected to its drain) is used as a load transistor     

Gate CD Control Considering Variation of Gate and STI Structure

We developed a fab-wide advanced process control system to control the critical dimension (CD) of gate electrode length in semiconductors. We also developed a model equation that predicts the gate CD by considering the structures of gate electrode and shallow trench isolation. This prediction model was also used to perform a factor analysis of gate CD variation. The effectiveness of the model in controlling feedforward was evaluated by both simulation and experiment. The CD variation of the wafers was improved from 8.9 nm in its 3 sigma without control to 3.5 nm with lot-to-lot feedforward control.     

Ring resonator composed of low loss polymer waveguides at 1.3 mu m

A channel waveguide ring resonator was successfully fabricated using polymers synthesized from deuterated methacrylate and deuterated fluoromethacrylate. Resonance curves with a finesse of 14.8 and an extinction ratio of 0.83 were obtained at a wavelength of 1.3 mu m. The corresponding waveguide loss was estimated to be 0.10 dB/cm. In addition, the temperature and polarisation characteristics of the resonance were investigated.<>     

Identification of the odour-active cyclic diketone cis-2,6-dimethyl-1,4-cyclohexanedione in roasted Arabica coffee brew

We investigated odour-active trace compounds in roasted Brazilian Arabica coffee. Aroma dilution extract analysis (AEDA) applied to the volatile oil extracted from roasted coffee brew revealed 34 odour-active compounds. Among these, a pungent-smelling unknown odour-active compound was determined. The volatile oil was fractioned by silica gel column chromatography. Gas chromatography–olfactometry (GC–O) and multidimensional gas chromatography–mass spectrometry (MDGC–MS) of the fraction which contained a significant amount of the target unknown compound revealed the cyclic 1,4-diketone, cis-2,6-dimethyl-1,4-cyclohexanedione, which had a pungent odour, and was thus first identified in roasted coffee. Model experiments revealed that cis-2,6-dimethyl-1,4-cyclohexanedione was formed via thermal degradation of sugars, especially monosaccharides, under alkaline conditions. Further, we demonstrated that 2-hydroxy-3-pentanone and 1-hydroxy-2-propanone, thermal degradation products of monosaccharides, were closely related to the formation of cis-2,6-dimethyl-1,4-cyclohexanedione.