物質・反物質化合物の研究：反水素化分子における自発転位

要約のみTohoku University木野康志課

Development of an Evolutionary Three-Dimensional Scroll Compressor

A novel three-dimensional scroll compressor was developed. The authors have produced 3D scroll compressor since 2004. The 3D scroll is able to compress refrigerant in axial direction as well as in existing radial direction by employing steps at the bottom and the tip of the scroll which change the height of compression chamber on the middle of the compression process. For the purpose of further performance improvement, the authors developed an evolutionary three-dimensional compression mechanism, named e-3D scroll . The e-3D scroll is equipped with a sloped tip and a sloped end plate in each scroll instead of the steps in the conventional 3D scroll. The height of compression chamber decreases continuously with progression of compression by the sloped shape. The e-3D scroll achieved considerable efficiency improvement compared to the conventional 3D scroll since there is no leakage loss in the steps while keeping the advantages of high compression ratio, large capacity and small size by the sloped tip and end plate. In addition, the noise and vibration of the e-3D scroll compressor reduced significantly since the rate of change of cylinder volume throughout the compression process and the torque variation in the rotation became smaller than the conventional 3D scroll. This article describes the compression mechanism and the performance improvement technology in the e-3D scroll

Pump-power-controlled L-band wavelength-tunable mode-locked fiber laser utilizing all polarization maintaining nonlinear polarization rotation

For the first time, we present the pump power-controlled wavelength-tunable mode-locked fiber laser in the L-band (1565 nm to 1625 nm), achieved by all-polarization maintaining (all-PM) nonlinear polarization rotation (NPR). The wavelength of the laser can be tuned over 20 nm, from 1568.2 nm to 1588.9 nm simply by controlling the pump power from 45 mW to 115 mW. In contrast to conventional wavelength tuning mechanisms such as optical bandpass filters, our tuning method is non-mechanical and electrically controllable, featuring simplicity and cost-effectiveness in a superior all-fiber design.Comment: 5 pages, 4 figure

Simple way of finding Ba to Si deposition rate ratios for high photoresponsivity in BaSi2 films by Raman spectroscopy

Since the photoresponsivity of BaSi2 is sensitive to a Ba-to-Si deposition rate ratio (R Ba/R Si), there is a need to determine the optimum value of R Ba/R Si. We grew 0.5 μm thick BaSi2 films with R Ba/R Si varied from 1.1–3.6 at 580 °C and 0.4–4.7 at 650 °C. The photoresponsivity reached a maximum at R Ba/R Si = 2.2 and 1.2, respectively. Raman spectroscopy revealed that the crystalline quality of BaSi2 became better with decreasing R Ba/R Si. However, as R Ba/R Si decreased further beyond these values, excess Si precipitated, showing that the optimum value of R Ba/R Si should be as small as possible without causing Si precipitates to form

Investigation of native defects in BaSi2 epitaxial films by electron paramagnetic resonance

We investigated photoresponse, photoluminescence (PL), and electron paramagnetic resonance (EPR) spectra of 0.5 μm thick BaSi2 films grown by molecular beam epitaxy using various Ba-to-Si deposition rate ratios (R Ba/R Si). BaSi2 films (R Ba/R Si = 2.2) showed the highest photoresponsivity at room temperature. In contrast, BaSi2 films with R Ba/R Si away from 2.2 showed low photoresponsivity but intense sub-bandgap PL at 9 K. An anisotropic EPR line was observed below 20 K for such BaSi2 films. The EPR line disappeared for BaSi2 films passivated with atomic hydrogen. Thereby, the PL and EPR signals are interpreted to originate from native defects in the BaSi2 films

Circulatory C-type natriuretic peptide reduces mucopolysaccharidosis-associated craniofacial hypoplasia in vivo

Skeletal alterations in the head and neck region, such as midfacial hypoplasia, foramen magnum stenosis and spinal canal stenosis, are commonly observed in patients with mucopolysaccharidosis (MPS). However, enzyme replacement therapy (ERT), one of the major treatment approaches for MPS, shows limited efficacy for skeletal conditions. In this study, we analysed the craniofacial morphology of mice with MPS type VII, and investigated the underlying mechanisms promoting jaw deformities in these animals. Furthermore, we investigated the effects of C-type natriuretic peptide (CNP), a potent endochondral ossification promoter, on growth impairment of the craniofacial region in MPS VII mice when administered alone or in combination with ERT. MPS VII mice exhibited midfacial hypoplasia caused by impaired endochondral ossification, and histological analysis revealed increased number of swelling cells in the resting zone of the spheno-occipital synchondrosis (SOS), an important growth centre for craniomaxillofacial skeletogenesis. We crossed MPS VII mice with transgenic mice in which CNP was expressed in the liver under the control of the human serum amyloid-P component promoter, resulting in elevated levels of circulatory CNP. The maxillofacial morphological abnormalities associated with MPS VII were ameliorated by CNP expression, and further prevented by a combination of CNP and ERT. Histological analysis showed that ERT decreased the swelling cell number, and CNP treatment increased the width of the proliferative and hypertrophic zones of the SOS. Furthermore, the foramen magnum and spinal stenoses observed in MPS VII mice were significantly alleviated by CNP and ERT combination. These results demonstrate the therapeutic potential of CNP, which can be used to enhance ERT outcome for MPS VII-associated head and neck abnormalities

L-band fiber laser mode-locked by all-polarization maintaining nonlinear polarization rotation

For the first time in the soliton regime, we demonstrated an L-band fiber laser mode-locked by all polarization-maintaining nonlinear polarization rotation. The self-starting laser centered at 1586.4 nm with long-term stability