Establishing the Japan-Store House of Animal Radiobiology Experiments (J-SHARE), a large-scale necropsy and histopathology archive providing international access to important radiobiology data

Purpose: Projects evaluating the effects of radiation, within the National Institutes of Quantum and Radiological Science and Technology (QST), National Institute of Radiological Sciences (NIRS), have focused on risk analyses for life shortening and cancer prevalence using laboratory animals. Genetic and epigenetic alterations in radiation-induced tumors have been also analyzed, with the aim of better understanding mechanisms of radiation carcinogenesis. As well as the economic and practical limitations of repeating such large-scale experiments, ethical considerations make it vital that we store and share the pathological data and samples of the animal experiments for future use. We are now constructing such an archive called the Japan-Storehouse of Animal Radiobiology Experiments (J-SHARE). Methods: J-SHARE records include information such as detailed experimental protocols, necropsy records and photographs of organs at necropsy. For each animal organs and tumor tissues are dissected, and parts are stored as frozen samples at -80 ˚C. Samples fixed with formalin are also embedded in paraffin blocks for histopathological analyses. Digital copies of stained tissues are being systematically saved using a virtual slide system linked to original records by barcodes. Embedded and frozen tissues are available for molecular analysis. Conclusion: Similar archive systems for radiation biology have been also under construction in the USA and Europe, the Northwestern University Radiation Archive (NURA), and STORE at the BfS, respectively. The J-SHARE will be linked with the sister-archives and made available for collaborative research to institutions and universities all over the world

Intranasal Delivery of Cholera Toxin Induces Th17-Dominated T-Cell Response to Bystander Antigens

Cholera toxin (CT) is a potent vaccine adjuvant, which promotes mucosal immunity to protein antigen given by nasal route. It has been suggested that CT promotes T helper type 2 (Th2) response and suppresses Th1 response. We here report the induction of Th17-dominated responses in mice by intranasal delivery of CT. This dramatic Th17-driving effect of CT, which was dependent on the B subunit, was observed even in Th1 or Th2-favored conditions of respiratory virus infection. These dominating Th17 responses resulted in the significant neutrophil accumulation in the lungs of mice given CT. Both in vitro and in vivo treatment of CT induced strongly augmented IL-6 production, and Th17-driving ability of CT was completely abolished in IL-6 knockout mice, indicating a role of this cytokine in the Th17-dominated T-cell responses by CT. These data demonstrate a novel Th17-driving activity of CT, and help understand the mechanisms of CT adjuvanticity to demarcate T helper responses

ZCS interleaved boost converter with saturable inductors for reverse-recovery reduction

Conventional DC-DC step-up converters present problems of low efficiency and low power density because of: 1. High power losses caused by hard-switching and reverse-recovery phenomenon. 2. High conduction losses produced by large peak currents when the converter has to operate at a high duty cycle. 3. Bulky and heavy cooling systems needed to dissipate the semiconductors losses. And, 4. Big and heavy capacitors and inductors required for smoothing and decoupling. Therefore, a novel Zero-Current-Switching two-phase interleaved boost converter with saturable inductors for reverse-recovery reduction is proposed. This converter can reduce the switching losses in the semiconductors due to the effect of the saturable inductors. Moreover, downsizing of the inductors and the output capacitor can be achieved due to the interleaving technique and the use of saturable inductors. In addition, high step-up operation can be achieved due to the presence of tapped-inductors. In this paper, the circuit configuration and the operation principle of the proposed converter and the reverse-recovery reduction behavior are presented. Finally, the effectiveness of the proposed converter is experimentally validated with a 600W prototype where a recovery-reduction of 58% was achieved.status: publishe

Coupling Coefficient Improvement and Electromagnetic Induced Noise Reduction using Short-Circuited Winding for Loosely Coupled Inductor

© 2016 The Institute of Electrical Engineers of Japan. A loosely coupled inductor for interleaved power converters has attracted interest for downsizing magnetic components. Although the loosely coupled inductor is usually designed by adjusting the coupling coefficient in order to meet the design specifications, the coupling coefficient is saturated by the fringing fluxes in the central leg and the external leakage fluxes in the case of the EE or EI magnetic core structures. It is a matter of concern that these fluxes are causes of electromagnetic induced noise and reduction in the downsizing performance. To solve this problem, this paper proposes a short-circuited winding for the coupled inductor in order to reduce the external leakage flux in the windings. The effectiveness of the coupled inductor with a short-circuit ring is evaluated with experimental tests.status: publishe

Analysis of Output Capacitor Voltage Ripple of the Three-Phase Transformer-Linked Boost Converter

© 2015 EPE Association and IEEE. The techniques of interleaving phases and magnetic coupling in power converters are effective downsizing the capacitive components as well as the inductive components in certain configurations. These techniques help tackle the problem of large mass and volume in autonomous electric vehicles as the use of the transformer-linked method in interleaved converters facilitates the miniaturization of the inductor, the output capacitor and the cooling system. Consequently, the analysis of all the characteristics of each component in the converter should be taken into account. This study presents the analysis of the output capacitor voltage ripple in the three-phase interleaved boost converter with coupled inductor (Transformer-linked). In this paper, the operating principle of the three-phase interleaved boost converter with coupled inductor is presented, then the output voltage ripple analysis is conducted for each mode of the operating principle, and finally the voltage ripple analysis is validated by experimental tests of a 1kW prototype.status: publishe

Reverse-Recovery Current Reduction in a ZCS Boost Converter with Saturable Inductors using Nanocrystalline Core Materials

© 2016 IEEE and EPE Association. Electric Vehicles demand high efficiency power converter in their powertrains in order to use the energy of the storage unit in a better way. Specifically, the power converters, that interface the storage unit with the motors, are usually composed of high-losses components. Moreover, the topologies used in these systems present conditions of hard switching and reverse recovery phenomena that reduce the total efficiency in the vehicle. This work analyzes the recovery-less boost converter that can achieve Zero-Current Switching, reverse-recovery reduction and softening of the switching transition. Due to the technique of using two saturable inductors. In addition, the use of next-generation magnetic materials for increasing the efficiency and reducing the reverse recovery current is studied. In this paper, the circuit configuration, the operating principle and the reverse-recovery reduction of the recovery-less converter is reviewed. Moreover, the comparison of ferrites and nanocrystalline soft magnetic materials is presented. Finally, the effectiveness of the proposed comparison is validated by experimental tests. As a result, reduction of the peak recovery current and increase of the efficiency are confirmed, achieving a 71% of reduction of the recovery current and 0.25% of efficiency increase at 1kW of output power.status: publishe

Gate Drive Circuit Suitable for a GaN Gate Injection Transistor

A GaN gate injection transistor (GIT) has great potential as a power semiconductor device. However, a GaN GIT has a diode characteristic at the gate-source, and a corresponding gate drive circuit is thus required. Several studies in the literature have proposed the gate drive circuits with the speed-up capacitors, but adding these capacitors complicates the gate drive circuit, and increases both the drive and reverse conduction losses. Moreover, driving a GaN GIT with such gate drive circuits becomes more susceptible to the false turn-on. In this paper, a gate drive circuit suitable for a GaN GIT without a speed-up capacitor is proposed. This type can provide the high-speed switching, and exhibit the low gate drive loss and reverse conduction loss. The proposed circuit also has high immunity against the false turn-on and stable gate-source voltage before and after startup. The drive loss of the proposed type is calculated and its validity is confirmed experimentally. Furthermore, the drive loss of the proposed type is compared with the conventional circuits. The result shows that the drive loss of the proposed type is improved by up to 50 %, compared with the conventional type. Finally, the proposed type is experimentally tested to drive a buck converter at the switching frequency of 150 kHz. The entire loss of the converter can be reduced by up to 9.2% at 250 W, compared with the conventional type

High Step-Up Interleaved Converter for Renewable Energy and Automotive Applications

High step-up DC-DC converters are widely used in many industrial appliances and recently introduced in renewable energy systems and automotive applications due to their high voltage gain capability. Nevertheless, current high step-up converters often employ additional circuitry with the purpose of increasing the voltage gain. Consequently, the converter will be bulky, heavy and expensive, because the use of these additional passive and active components influences the power density and the cost of the whole application. Therefore, the well-known techniques of interleaving phases and magnetic coupling are applied in a novel high step-up converter with the purpose of helping tackle these problems. Using these techniques, high voltage gain and reduction of circuit elements can be achieved. In this paper, the operating principle of this converter is summarized and the voltage gain is analyzed. Moreover, the analyzed topology is compared with several outstanding high step-up converters recently proposed that use the concept of interleaving phases and magnetic coupling. Finally, the analyzed converter was experimentally tested and the effectiveness in terms of higher voltage gain and number of components than the current topologies is validated.status: publishe

Effect of inductor parasitic resistances on the voltage gain of high step-up DC-DC converters for electric vehicle applications

© The Institution of Engineering and Technology 2018. Reconfiguration, sizing and downsizing of the storage unit, in electrically propelled vehicles, are techniques that have been reported effective to improve the shelf life and performance of the storage cells. However, these solutions might decrease the rated voltage of the storage unit and therefore DC-DC converters with high voltage gain are suitable solutions to connect these low-voltage units to the motor drive, keeping a good performance of the vehicle. Moreover, parasitic resistances presented in the components of these converters have proved to influence the efficiency and the voltage gain of the converter. The ideal voltage gain of four high step-up converters is analysed, derived, and compared. These converters were selected because of their potential to be applied in electric mobility and their similarity in the techniques that use to achieve high voltage gain: interleaving phases and magnetic integration. One of the analysed topologies is proposed by the authors. Afterwards, the parasitic resistance effect is analysed to obtain the non-ideal voltage gain and the efficiency of these four topologies. Finally, the topology that presents the best trade-off between the non-ideal voltage gain and the efficiency is experimentally tested with a 100 W prototype.status: publishe