22 research outputs found
Ultrafast light-driven simultaneous excitation of coherent terahertz magnons and phonons in multiferroic BiFeO3
Ultrafast light-driven simultaneous excitation of coherent terahertz magnons and phonons in multiferroic BiFeO3
The ultrafast switching of magnetization in multiferroic materials by a femtosecond laser could provide various advantages in photonics and magnonics. An efficient approach to control the light-matter interaction is the modulation of ultrafast coherent magnons and phonons in the high-frequency range. Spontaneous Raman andinfraredspectrarevealtheexcitationofmagnonsandopticalphononsinmultiferroicBiFeO3 inthesub-fewterahertz range. However, coherent control of such quasiparticles has not been achieved yet. In this study, we demonstrate that linearly polarized laser pulses simultaneously excite coherent magnons [out-of-plane ( ) and in-plane ( ) cyclone modes] and optical phonon (E mode) in BiFeO3. Experimental results in conjugation with phenomenological theory, by considering three uniformly distributed magnetic domains, reveal that impulsive stimulated Raman scattering is responsible for the generation of coherent magnons and phonons in BiFeO3. The observation of these terahertz magnon and optical phonon modes paves the way for the development of ultrafast magnetoelectro-optical devices
RENAL TRANSPLANTATION IMPROVES CARDIAC FUNCTION
There is mounting evidence that chronic kidney disease is a major contributor to severe cardiac damage. Although renal transplantation (RT) is an effective strategy in patients with end-stage renal disease (ESRD), the effects on cardiac function remain unclear. This study determined the effects of RT on left ventricular (LV) morphology and function in a retrospective longitudinal analysis of echocardiographic data collected in RT (n=17) and maintenance hemodialysis (HD ; n=19) groups from 2003 to 2008.Echocardiographic data obtained within 6 months and at over 3 years were compared with the data before transplantation. Improved blood pressure and anemia were observed with RT, but not HD. In contrast to the HD group, the left ventricular mass index (LVMI) in the RT group was decreased from 195.2 ± 52.1 to 162.5 ± 30.8 g/m2 ( p<0.05). In addition, the LV ejection fraction was improved in the RT group from 63.0 ± 17.1% to 79.5 ± 3.3% ( p<0.01), but not in the HD group. The rate of reduction of LVMI in the RT group was greater in patients with good control of hemoglobin.In conclusion, RT has beneficial effects on LV hypertrophy and function, as well as on ESRD
Controlled/Living Ring-Opening Polymerization of Glycidylamine Derivatives Using <i>t</i>‑Bu‑P<sub>4</sub>/Alcohol Initiating System Leading to Polyethers with Pendant Primary, Secondary, and Tertiary Amino Groups
The combination of <i>t</i>-Bu-P<sub>4</sub> and alcohol
was found to be an excellent catalytic system for the controlled/living
ring-opening polymerization (ROP) of <i>N</i>,<i>N</i>-disubstituted glycidylamine derivatives, such as <i>N</i>,<i>N</i>-dibenzylglycidylamine (DBGA), <i>N</i>-benzyl-<i>N</i>-methylglycidylamine, <i>N</i>-glycidylmorpholine, and <i>N</i>,<i>N</i>-bis(2-methoxyethyl)glycidylamine,
to give well-defined polyethers having various pendant tertiary amino
groups with predictable molecular weights and narrow molecular weight
distributions (typically <i>M</i><sub>w</sub>/<i>M</i><sub>n</sub> < 1.2). The <i>t</i>-Bu-P<sub>4</sub>-catalyzed
ROP of these monomers in toluene at room temperature proceeded in
a living manner, which was confirmed by a MALDI-TOF MS analysis, kinetic
measurement, and postpolymerization experiment. The well-controlled
nature of the present system enabled the production of the block copolymers
composed of the glycidylamine monomers. The polyethers having pendant
primary and secondary amino groups, i.e., poly(glycidylamine) and
poly(glycidylmethylamine), respectively, were readily obtained by
the debenzylation of poly(DBGA) and poly(BMGA), respectively, through
the treatment with Pd/C in THF/MeOH under a hydrogen atmosphere. To
the best of our knowledge, this report is the first example of the
controlled/living polymerization of glycidylamine derivatives, providing
a rapid and comprehensive access to the polyethers having primary,
secondary, and tertiary amino groups
Synthesis of Star- and Figure-Eight-Shaped Polyethers by <i>t</i>‑Bu‑P<sub>4</sub>‑Catalyzed Ring-Opening Polymerization of Butylene Oxide
The synthesis of well-defined four-armed
star-shaped poly(butylene oxide) and figure-eight-shaped poly(butylene
oxide)s (<i>s</i>-PBO and 8-PBO, respectively) with predicted
molecular weights and narrow molecular weight distributions (<i>M</i><sub>w</sub>/<i>M</i><sub>n</sub>s) was achieved
by the <i>t</i>-Bu-P<sub>4</sub>-catalyzed ring-opening
polymerization (ROP) of butylene oxide (BO). The <i>t</i>-Bu-P<sub>4</sub>-catalyzed ROP of BO using 1,2,4,5-benzenetetramethanol
as the initiator produced <i>s</i>-PBOs having number-average
molecular weights (<i>M</i><sub>n,NMR</sub>s) ranging from
ca. 4000 to 12 000 g mol<sup>–1</sup> and narrow <i>M</i><sub>w</sub>/<i>M</i><sub>n</sub>s of <1.03.
Cleavage of the linkage between the initiator residue and PBO arms
in <i>s</i>-PBO provided evidence for the homogeneous growth
of each arm during the polymerization. The synthesis of 8-PBO was
carried out through three reaction steps including (1) the synthesis
of a PBO possessing two azido groups at the chain center ((N<sub>3</sub>)<sub>2</sub>-(PBO)<sub>2</sub>) by the ROP of BO using 2,2-bis((6-azidohexyloxy)methy)propane-1,3-diol
as the initiator, (2) the introduction of an ethynyl group at the
two ω-chain ends by etherification using propargyl bromide to
give the ω,ω′-diethynyl poly(butylene oxide) with
two azido groups ((N<sub>3</sub>)<sub>2</sub>-(PBO-CCH)<sub>2</sub>), and (3) the intramolecular click cyclization of (N<sub>3</sub>)<sub>2</sub>-(PBO-CCH)<sub>2</sub> using the copper(I)
bromide/<i><i>N,N</i>,N′,N″,N″</i>-pentamethyldiethylenetriamine catalyst in DMF under high dilution
conditions. Size exclusion chromatography, FT-IR, and <sup>1</sup>H NMR measurements confirmed that the click reaction proceeded in
an intramolecular fashion to give 8-PBOs having <i>M</i><sub>n,NMR</sub>s ranging from ca. 3000 to 12 000 g mol<sup>–1</sup> and narrow <i>M</i><sub>w</sub>/<i>M</i><sub>n</sub>s of <1.06. The viscosity property of <i>s</i>-PBO and 8-PBO was evaluated together with linear and cyclic
PBOs (<i>l</i>-PBO and <i>c</i>-PBO, respectively).
The intrinsic viscosity ([η]) of <i>l</i>-PBO, <i>c</i>-PBO, <i>s</i>-PBO, and 8-PBO decreased in the
order of <i>l</i>-PBO > <i>s</i>-PBO > <i>c</i>-PBO > 8-PBO
Comparison of the occurrence of sleep bruxism under accustomed conditions at home and under polysomnography conditions in a sleep laboratory
Purpose: We aimed to clarify the relationship between the number of sleep bruxism (SB) bursts at home and in a laboratory equipped with polysomnography with audio-video recording (PSG-AV). We applied an identical single-channel wearable electromyography (EMG) device for both types of SB burst scorings. Methods: The subjects were 20 healthy student volunteers (12 men and 8 women; mean age, 21.9 years) who were clinically diagnosed with bruxism based on the criteria set forth by the International Classification of Sleep Disorders (ICSD-2). We used a wearable EMG device attached to the masseteric area (the FLA-500-SD [FLA]), for scoring SB bursts at home and in the laboratory. PSG-AV was set within the laboratory environment as well. The mean interval for both sleep studies was 28.8 days. EMG bursts with amplitudes greater than twice the baseline amplitude and with durations of longer than 0.25 s were selected. EMG bursts with amplitudes >= 5% MVC (maximum voluntary contraction), >= 10% MVC, and >= 20% MVC were selected as well. A cluster of bursts was defined as an episode. Results: In all the conditions for selecting EMG bursts specified above, the number of SB bursts and episodes recorded under laboratory conditions was statistically significantly smaller than that recorded at home. There were no statistically significant differences between the data obtained on the first and second recording days. Conclusion: The results of this study suggest that the unfamiliar environment of a sleep laboratory equipped with PSG-AV affects the emergence of SB as compared with home conditions
AUTOMATIC ACQUISITION OF CT RADIATION DOSE DATA: USING THE DIAGNOSTIC REFERENCE LEVEL FOR RADIATION DOSE OPTIMIZATION
Automatic acquisition of CT radiation dose data: Using the diagnostic reference level for radiation dose optimization
The present work describes that we try to construct a system that collects dose information that performed CT examination from multiple facilities and unified management. The results of analysis are compared with other National diagnostic reference level (DRL), and the results are fed back to each facility and the cause of the abnormal value is investigated for dose optimization. Medical information collected 139 144 tests from 33 CT devices in 13 facilities. Although the DRL of this study is lower than that of Japan DRL, it was higher than the DRL of each country. When collecting all the examination, it is thought that the variation of the dose due to the error other than the intended imaging site is large. In future, we should continue to collect information in order to DRL renewal and we also think that it is desirable to collect information on physique and detailed scan region as well