Generation of multifrequency laser emission quasi equally spaced throughout the entire visible region

A circularly polarized, monochromatic laser beam is focused into a Raman cell, which contains hydrogen to generate rotational stimulated Raman emission. After linear polarization, this two-color (separated by 587 cm(-1)) laser beam is focused several times into a second Raman cell that is filled with hydrogen to generate a multifrequency laser emission. Many rotational and vibrational lines are generated efficiently by this multipass effect. Eighteen colors that are quasi equally spaced with a rather flat intensity distribution are generated throughout the entire visible region. The present multifrequency laser emission may be advantageously used for illumination in a higher-grade display, such as a laser light show.     

Analysis of PD-generated SF/sub 6/ decomposition gases adsorbed on carbon nanotubes

Chemical byproducts analysis has been recognized as a powerful diagnosis method for SF₆ gas-insulated switchgear (GIS). The authors have previously demonstrated that a carbon nanotube (CNT) gas sensor could detect partial discharge (PD) generated in SF₆ gas. However, PD-generated decomposition gas species, which were responsible for the CNT gas sensor response, have not been identified yet. In this paper, two kinds of experiments were conducted in order to identify the responsible decomposition gas species. At first, the decomposition gas molecules adsorbed on CNTs were analyzed by Fourier transformation infrared (FTIR) spectroscopy. FTIR absorbance was observed around 735 cm^-1 after CNTs were exposed to PD generated in SF₆. In the second experiment, the CNT gas sensor responses to typical SF₆ decomposition products (HF and SF₄) were examined. The CNT gas sensor responded to these gases in the same way as to PD generated in SF₆. SF₄ response was larger than HF response. Based on these results, SF ₄ and SOF₂ emerged as candidates for the responsible decomposition gases. Electrochemical interactions between adsorbed gas molecules and CNT were discussed based on theoretical predictions of molecular orbital calculations. The calculation results suggested that both of SOF₂ and SF₄ could increase the CNT gas sensor conductance     

An agent architecture for strategy-centric adaptive QoS control in flexible videoconference system

In this paper, we propose an agent architecture to improve flexibility of a videoconference system with strategy-centric adaptive QoS (Quality of Service) control mechanism. The proposed architecture realizes more flexibility by changing their QoS control strategies dynamically. To switch the strategies, system considers the properties of problems occurred on QoS and status of problem solving process. This architecture is introduced as a part of knowledge base of agent that deals with cooperation between software module of videoconference systems. We have implemented the mechanism, and our prototype system shows its capability of flexible problem solving against the QoS degradation, along with other possible problems within the given time limitation. Thus we confirmed that the proposed architecture can improve its flexibility of a videoconference system compared to traditional systems. Takuo Suganuma, Dr.Eng.: He is a research associate of Research Institute of Electrical Communication of Tohoku University. He received a Dr.Eng. degree from Chiba Institute of Technology in 1997. His research interests include agent-based computing and design methodology for distributed systems. He is a member of IPSJ, IEICE and IEEE. SungDoke Lee: He is a Ph.D. Student in the Graduate School of Information Sciences in Tohoku University. He received his MEng degree at Chonbuk National University, Korea in 1991. His research interests include Flexible Network and Knowledge of Agent. Tetsuo Kinoshita, Dr.Eng.: He is an associate professor of Research Institute of Electrical Communication of Tohoku University. He received a Dr.Eng. degree in information engineering from Tohoku University, Japan. His research interests include knowledge engineering, cooperative distributed processing and agent-based computing. He received the the IPSJ Best Paper Award in 1997, etc. He is a member of IPSJ, IEICE, JSAI, AAAI, ACM and IEEE. Norio Shiratori, Dr.Eng.: After receiving his Dr.Eng degree at Tohoku University, he joined the Research Institute of Electrical Communication of Tohoku University in 1977, and is now a professor at the same University. He has been engaged in research on distributed processing system, and flexible intelligent network. He received the 25th Anniversary of IPSJ Memorial Prize-Winning Paper Award in 1985, the 6th Telecommunications Advancement Foundation Incorporation Award in 1991, the Best Paper Award of ICOIN-9 in 1994, the IPSJ Best Paper Award in 1997, etc. He has been named a Fellow of the IEEE for his contributions to the field of computer communication networks.     

Combustion of Aluminum Particles near the Burning Surface in AP/AN Composite Propellants

Aluminum (Al) particles are commonly used in ammonium perchlorate (AP) composite propellants of solid rockets for increasing performance. When propellants including Al particles burn, Al particles easily agglomerate on the burning surface of the propellant. The diameters of agglomerated Al particles are greater than those of mixed particles. The combustion efficiency of the propellant decreases with increasing burning time of the agglomerated Al particles. Therefore, it is important to observe how the agglomerated Al particles burn on the burning surface of AP composite propellant. A lot of researchers have studied Al agglomerate characteristics. Previous studies clarified the relation between the agglomerated Al particle diameter and luminous flame diameter around Al particles near the burning surface. The shapes of luminous flames around agglomerated Al particles are spherical or elliptical. This study evaluates the shapes of the luminous flame around agglomerated Al particles at a constant diameter or a different diameter. When the proportion of the luminous flame diameter (D_f) to the diameter of agglomerated Al particles (D₀) is 1.54–1.71 at a constant D₀, the luminous flames are almost perfectly spherical. Otherwise, the luminous flames are elliptical at a constant D₀. Furthermore, when D_f/D₀ is close to the mean value, the luminous flame is more spherical than elliptical at different D₀. The evaporation rate and the burning rate of Al vapor are inversely proportional to D₀. The oxidation gas temperatures were changed and the activation energy of Al vapor was obtained as 39.2 kJ mol⁻¹.     

Determination of motility forces of bovine sperm cells using an "optical funnel"

An optical funnel, a new technique for the evaluation of the force of a microorganism, was applied to the determination of the motility force of bovine sperm cells. In this approach, sperm cells, suspended in an aqueous solution, are introduced into a flow cell, to which radiation pressure is applied from the direction opposite to a medium flow. The sperm cell, which is moving in a stream, is captured by radiation pressure and forced to move to the position at which the force induced by the laser radiation is equal to the force induced by a medium flow. The sperm cell then escapes by its own power on the way to this equilibrium (entrapping) position. The radiation force increases with decreasing distance from the focal point, and as a result, the force of the sperm cell can be determined by measuring the position where the sperm cell escaped against the laser irradiation field. The motility force of the sperm cell was measured in aqueous solution at different pH values and potassium ion concentrations. It was possible to measure more than 250 sperm cells in 3 h. Thus, the optical funnel has potential for use as a rapid and repetitive means for the determination of the motility force of the sperm cell.     

Supersonic jet/multiphoton ionization/mass spectrometry of dioxins formed by the thermal reaction of phenols in the absence and presence of an FeCl3 catalyst

Dioxins, which are thermally produced from several precursor molecules, were investigated by supersonic jet/multiphoton ionization/time-of-flight mass spectrometry (SSJ/MPI/TOF-MS). Dibenzofuran and dibenzo-p-dioxin were efficiently generated from o-chlorophenol and also from phenol after a chlorination reaction with FeCl3. The present technique was employed for the continuous monitoring of a specified isomer, e.g., m-chlorophenol, which is formed at relatively low temperatures by chlorination of phenol with FeCl3. A dimerization reaction that forms a dibenzo-p-dioxin, e.g., dichlorodibenzo-p-dioxin from 2,4-dichlorophenol, at relatively high temperatures was also investigated. The number of chlorine atoms in the dioxin molecule was largely correlated with the number of chlorine atoms in the precursor molecule. However, some unexpected compounds, which probably occur by dechlorination and rearrangement reactions, were also found. Thus, the SSJ/MPI/TOF-MS technique represents a sensitive, as well as selective, analytical method for monitoring thermally generated dioxins.     

Production of functional substances from black rice bran by its treatment in subcritical water

Black rice bran was treated by water and subcritical water at temperatures ranging from 20 to 260 °C for 5 min and at 200 and 260 °C for 5-120 min. The bran extracts were analyzed for their radical scavenging activity, protein and carbohydrate contents, molecular-mass distribution, antioxidation activity, emulsifying activity, and emulsion-stabilizing activity. The radical scavenging activity and the protein content of the extract were higher at higher treatment temperature. The carbohydrate content also increased with increasing temperature up to 200 °C, then steeply decreased at the temperatures higher than 200 °C. The bran extracts treated at 260 °C for 5 min exhibited a suppressive activity toward autoxidation of linoleic acid with the increasing the weight ratio of the bran extract to linoleic acid. The bran extracts prepared at 40-200 °C for 5 min showed the emulsifying- and emulsion-stabilizing activities, while the extracts prepared at 220-260 °C were low in the activities.     

Enhancement of thermostability of kojibiose phosphorylase from Thermoanaerobacter brockii ATCC35047 by random mutagenesis

Random mutation by error-prone PCR was introduced into kojibiose phosphorylase from Thermoanaerobacter brockii ATCC35047. One thermostable mutant enzyme, D513N, was isolated. The D513N mutant enzyme showed an optimum temperature of 67.5-70 degrees C (the wild type, 65 degrees C), and thermostability up to 67.5 degrees C (the wild type, up to 60 degrees C). The half-lives of D513N were estimated to be 135 h at 60 degrees C, 110 min at 70 degrees C and 6 min at 75 degrees C, respectively. They were about 1.6-fold, 7-fold and 6-fold longer than those of the wild-type enzyme, respectively.     

Micro-/nanostructural investigation of laser-cut surfaces of single- and polycrystalline diamonds

Micrometer- to nanometer-scale structures of the cut surfaces of single- and polycrystalline diamonds by a pulsed ultraviolet laser have been thoroughly investigated by scanning and transmission electron microscopy. Within the laser-cut grooves, the processed diamond surfaces are extensively covered with laser-modified debris which consists of complex layered units of graphite with various crystallinities. The units consist of 1) highly oriented graphite, 2) corrugated graphite, and 3) nanocrystalline graphite, which are sequentially located from the surface of the underlying diamond substrate to the center of the grooves. Detailed textural examinations revealed that the highly oriented graphite unit is a product of the initial graphitization of diamond by a solid-state diffusion process, whereas the latter two units are deposition products from the liquid and/or vapor phases of carbon in the later stage. The present study demonstrates that the laser-cutting of diamonds proceeds in a two-step process: 1) extensive graphitization of laser-scanning path and 2) subsequent sublimation of the pre-formed graphite. These processes are basically identical among the three different types of diamonds (single crystal type Ib, single crystal type IIa and nano-polycrystalline aggregate) tested in this study.