Coherent lattice vibrations in single-walled carbon nanotubes

We have generated and detected coherent lattice vibrations in single-walled carbon nanotubes corresponding to the radial breathing mode (RBM) using ultrashort laser pulses. Because the band gap is a function of diameter, these RBM-induced diameter oscillations cause ultrafast band gap oscillations, thereby modulating the interband excitonic resonances at the phonon frequencies (3-9 THz). Excitation spectra show a large number of pronounced peaks, allowing the determination of the chiralities present in particular samples and relative population differences of particular chiralities between samples.     

LiNbO3 based optical devices for fiber communication

h efficiency wavelength converters.     

Aging of complex heart rate dynamics

We reveal unexpected origins of age induced departure from 1/f-type temporal scaling in healthy human heart rate. Contrary to the widely established view, we provide evidence that age induced dynamical imbalance in the autonomic control is not due to the emergent functional dominance of the sympathetic nervous system (SNS), but due to emerging (age dependent) relative dynamic dominance of the parasympathetic nervous system function. In particular, we demonstrate that the age induced alterations of healthy heart rate dynamics asymptotically resemble those in so-called primary autonomic failure with neurogenic SNS dysfunction and in other neurodegenerative disorders, including Parkinson's disease even without known autonomic abnormalities. Based upon this, we propose a novel picture of "autonomic aging," characterized by an insufficiency of the SNS function to cope dynamically with various environmental stimuli.     

Evaluation of the change in chemical structure of acrylonitrile butadiene rubber after high-pressure hydrogen exposure

The influence of high-pressure hydrogen on the chemical structure of organic materials is essential for designing suitable materials for the safe and efficient use of hydrogen. In this paper, we clarify the cause and mechanism of “explosive failure by decompression” (XDF) in rubber used under high-pressure hydrogen circumstances, and the chemical structure of acrylonitrile butadiene rubber (NBR), which is commonly used for O-rings, was analyzed after exposure to hydrogen at 100 MPa. Solid-state nuclear magnetic resonance (NMR) and liquid-phase NMR for ¹H and ¹³C, as well as infrared and Raman spectroscopy, were employed for the evaluation. The results show no evidence of structural changes in NBR such as hydrogenation of the olefinic bonds in butadiene or of the cyano groups in acrylonitrile.     

Interactions of supported nickel and nickel oxide catalysts with methane and steam at high temperatures

The catalytic performance of cermets made of 10% nickel or nickel oxide supported on YSZ (yttria-stabilized zirconia) for chemical looping combustion (CLC) and steam reforming (SR) of methane at 700 °C is investigated. Steam reforming of methane over the reduced catalyst resulted in a syngas containing more than 70% hydrogen and about 15% carbon monoxide. Chemical looping combustion of methane with insufficient lattice oxygen could potentially lead to 40–65% hydrogen rich gas products. Prolonged induction period (e.g. 30–80 min) in reduction of nickel oxide by methane has been observed in the presence of steam. The span of induction period increases by increasing steam partial pressure. It is hypothesized that the delayed reduction of nickel oxide is related to the retarding effect of steam on autocatalytic reactions of methane and hydrogen with lattice oxygen of nickel oxide and the subsequent reforming reactions.     

Hydrogen trapped at intermetallic particles in aluminum alloy 6061-T6 exposed to high-pressure hydrogen gas and the reason for high resistance against hydrogen embrittlement

Hydrogen (¹H) trapped at intermetallic particles (IPs) in an aluminum alloy, 6061-T6, was visualized with secondary ion mass spectrometry (SIMS) by precisely excluding the false signal which is caused by background hydrogen (H_BG). The interference of the H_BG was avoided by a unique continuous pre-sputtering (pre-digging) by a primary ion beam of SIMS into a sample in combination with silicon sputtering prior to the SIMS measurement of the sample and we succeeded in visualizing the exact signal of ¹H trapped by IPs at subsurface layer of the sample charged in high-pressure hydrogen gas. The thermal desorption analysis clarified that the desorption energy (E_d) of the IPs was 200 kJ/mol or higher, which was extremely higher than E_d for lattice interstice, dislocations, and vacancies. High density hydrogen was concentratedly trapped at IPs in the subsurface layer in contact with the hydrogen gas. This nature causes an extremely low effective hydrogen diffusivity of 6061-T6 of the order of 10^?14 m²/s even at 200 °C and may eventually give a high HE resistance to 6061-T6.     

Phase transition and proton transport characteristics in CsH2PO4/SiO2 composites

The stabilization of superprotonic phase in neat CsH₂PO₄ and CsH₂PO₄/SiO₂ composites as well as the anomalous phase transformation with a large hysteresis was investigated through proton conductivity, thermal analysis and Raman spectroscopy. The reversibility of the transition to the superprotonic phase and the phase transformation between monoclinic phase and cubic phase in neat CsH₂PO₄ at around T_c = 230 °C was confirmed under humidified and sealed conditions. In CsH₂PO₄/SiO₂ composites, a large asymmetric thermal hysteresis in the conductivity appeared, i.e. significant supercooling in the superprotonic phase was induced in silica matrices. A differential thermal analysis revealed that the temperature of a reverse transition from the cubic phase (superprotonic phase) to the monoclinic phase decreased in the composites. This effect became significant with an increase in silica volume fraction. The stabilization of superprotonic phase (cubic phase) in the composites will be induced by shear elastic forces at the interface between CsH₂PO₄ and silica particles. The main origin of the anomalous asymmetric thermal hysteresis in proton conductivity is the phase stability arising from the shear elastic forces and a proton-conducting network in silica matrices.     

Molecular Classification and Overcoming Therapy Resistance for Acute Myeloid Leukemia with Adverse Genetic Factors

The European LeukemiaNet (ELN) criteria define the adverse genetic factors of acute myeloid leukemia (AML). AML with adverse genetic factors uniformly shows resistance to standard chemotherapy and is associated with poor prognosis. Here, we focus on the biological background and real-world etiology of these adverse genetic factors and then describe a strategy to overcome the clinical disadvantages in terms of targeting pivotal molecular mechanisms. Different adverse genetic factors often rely on common pathways. KMT2A rearrangement, DEK-NUP214 fusion, and NPM1 mutation are associated with the upregulation of HOX genes. The dominant tyrosine kinase activity of the mutant FLT3 or BCR-ABL1 fusion proteins is transduced by the AKT-mTOR, MAPK-ERK, and STAT5 pathways. Concurrent mutations of ASXL1 and RUNX1 are associated with activated AKT. Both TP53 mutation and mis-expressed MECOM are related to impaired apoptosis. Clinical data suggest that adverse genetic factors can be found in at least one in eight AML patients and appear to accumulate in relapsed/refractory cases. TP53 mutation is associated with particularly poor prognosis. Molecular-targeted therapies focusing on specific genomic abnormalities, such as FLT3, KMT2A, and TP53, have been developed and have demonstrated promising results.