The spin-lattice relaxation times
T
1
of an unstable nucleus
19
O (
T
1/2
= 26.9 s,
I
= 5/2) implanted into Y
2
O
3
stabilized ZrO
2
(YSZ), which is a solid oxide fuel cell material, were measured at
...T
= 278 − 333 K by means of the
β
-NMR technique, using a highly spin polarized
19
O beam produced via the heavy ion reaction. The motional correlation times
τ
c
for oxygen motion derived from the
T
1
data are on the same straight line on the Arrhenius plot as those derived from the previous
17
O-NMR data at above the room temperature. This indicates that
19
O ions implanted into YSZ from outside seem to exhibit the same behavior as oxygen ions in the host YSZ material.
We have developed a new and compact β-nuclear magnetic resonance (NMR) system using beta-radioactive nuclei. By using a Halbach array permanent magnet to create a static magnetic field, and a ...scintillating fiber as a detector, we succeeded in significantly reducing the size and weight of the entire system. The performance of the new spectrometer was tested and evaluated by observing an NMR spectrum of
19
O (
T
1/2
= 26.9 s,
I
= 5/2) in TiO
2
.
We measured the energy dependence of the total reaction cross sections (σR) for the proton drip-line nucleus of neon isotopes, 17Ne, with a solid hydrogen target. The σR on a proton target in the ...low- and intermediate-energy regions were provided, where only a few values are available for unstable nuclei. The new data were compared with theoretical calculations using the Glauber model. In the low-energy region (∼100A MeV), the theoretical cross sections overestimate the experimental ones, whereas the theoretical ones significantly underestimate the experimental data in the intermediate energy region (∼300-500A MeV). We discuss several possibilities for solving this discrepancy. This work suggests the necessity of more careful investigations of the energy dependence of σR for various nuclei on a proton target to determine the nuclear size properties precisely.
The technique of laser resonance ionization is employed for an element-selective ionization of multi-nucleon transfer reaction products which are stopped and neutralized in a gas cell filled with ...argon gas at 50kPa. We have been searching for efficient laser ionization schemes for refractory elements of Z=73–78 using a time-of-flight mass-spectrometer (TOF-MS) chamber. To evaluate the isotope shift and ionization efficiency for each candidate of the ionization scheme, isotope separation using the TOF-MS was devised. The TOF-MS was designed to separate the isotopes using two-stage linear acceleration with a mass resolving power M/ΔM of >350. A mass resolving power of 250 was experimentally confirmed by measuring the TOF of laser-ionized tantalum (Z=73) ions with mass number 181. We searched for a laser resonance ionization scheme of tantalum using the TOF-MS.
Nuclear physics experiments with ion storage rings Litvinov, Yu.A.; Bishop, S.; Blaum, K. ...
Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms,
12/2013, Letnik:
317, Številka:
PART B
Journal Article
Recenzirano
Odprti dostop
•Accurate mass measurements of stored exotic nuclei.•Beta decay of highly-charged ions.•In-ring reactions for nuclear structure and astrophysics.•Dielectronic recombination on radioactive ...ions.•Future storage ring projects.
In the last two decades a number of nuclear structure and astrophysics experiments were performed at heavy-ion storage rings employing unique experimental conditions offered by such machines. Furthermore, building on the experience gained at the two facilities presently in operation, several new storage ring projects were launched worldwide. This contribution is intended to provide a brief review of the fast growing field of nuclear structure and astrophysics research at storage rings.
Construction of rare-RI ring at RIKEN RI Beam Factory Yamaguchi, Y.; Wakasugi, M.; Uesaka, T. ...
Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms,
12/2013, Letnik:
317
Journal Article
Recenzirano
An isochronous mass spectroscopy system using a newly constructed storage ring named the “rare-RI ring” is expected to be implemented at the RIKEN Nishina Center to determine the masses of ...short-lived rare nuclei including those in the r-process region with a relative precision of the order of 10-6 even for only one particle. In an isochronous storage ring, the mass is determined by measuring the revolution time of each nucleus. Our rare-RI ring consists of six magnetic sectors, and each sector consists of four bending magnets. To precisely optimize the isochronous conditions of the circulating particles for large acceptance, we install ten trim coils to half of the bending magnets. A fast-response and fast-charging kicker system enables selective and efficient injection of the produced rare nuclei into the ring one by one, along with facilitating efficient extraction of the circulating particles for time-of-flight measurement. Construction of the rare-RI ring was begun in the middle of the fiscal year 2012 at the RIKEN RI Beam Factory, and the ring is expected to be fully functional by 2015.
Repair of neonatal tetralogy of Fallot (TOF) has low mortality. Debate continues regarding the initial management of cyanotic or duct-dependent infants with TOF and adverse risk factors. While repair ...can and has been performed in these patients, it is associated with increased morbidity.
We review the effectiveness of right ventricular outflow tract (RVOT) stenting in the symptomatic young infant with TOF.
Clinical, echocardiographic, angiographic and haemodynamic data were reviewed for nine patients who underwent 11 RVOT stenting procedures from October 1994 to August 2007.
The pulmonary valve was deemed unsalvageable in all patients (median valve diameter 3.7 mm (range 2.7-4.2), Z-score -6.7 (range -9.7 to -5.4). RVOT stenting improved arterial oxygen saturation from a median of 73% (60-85%) to 94% (90-98%) (p = 0.008). Median Z-score for the left pulmonary artery increased from -4.9 (-7.8 to -2.4) before stent implantation to -1.5 (-4.2 to -0.2) (p = 0.02) before surgical repair. Median Z-score for the right pulmonary artery increased from -3.7 (-6.8 to -1.9) to -0.8 (-2.5 to 0.1) (p = 0.008). Median Nakata index increased from 56 mm(2)/m(2) (21-77) to 150 mm(2)/m(2) (123-231) (p = 0.008). There were no procedural complications. Six patients have undergone successful repair. There were no deaths.
In the symptomatic young infant with TOF, stenting of the RVOT provides a safe and effective management strategy, improving arterial oxygen saturation and encouraging pulmonary artery growth.
Delay-line PPAC for high-energy light ions Kumagai, H.; Ozawa, A.; Fukuda, N. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
09/2001, Letnik:
470, Številka:
3
Journal Article
Recenzirano
We have developed a delay-line parallel-plate avalanche counter (PPAC) with high detection efficiency for high-energy light ions. A large signal-to-noise ratio was achieved by a newly designed ...pre-amplifier and the usage of C
3F
8 gas at a pressure of
30
Torr
. The counter has been tested with beams of
90
A
MeV
7
Li
at RIKEN,
340
A
MeV
12
C
at GSI, and
254
A
MeV
8
B
at GSI. We achieved high detection efficiencies (>95%) for all of these ions. Furthermore, we achieved reasonable position and timing resolutions.
Isochronous Mass Spectrometry (IMS) in heavy-ion storage rings is an excellent experimental method for precision mass measurements of exotic nuclei. In the IMS, the storage ring is tuned in a special ...isochronous ion-optical mode. Thus, the mass-over-charge ratios of the stored ions are directly reflected by their respective revolution times in first order. However, the inevitable momentum spread of secondary ions increases the peak widths in the measured spectra and consequently limits the achieved mass precision. In order to achieve a higher mass resolving power, the ring aperture was reduced to 60 mm by applying a mechanical slit system at the dispersive straight section. The momentum acceptance was reduced as well as better isochronous conditions were achieved. The results showed a significant improvement of the mass resolving power reaching 5.2×105, though at the cost of about 40% ion loss.
Histamine is an important mediator in immune responses, but it is unclear whether periodontal tissues express histamine receptors and are able to respond to histamine. We hypothesized that histamine, ...inflammatory cytokines, and bacterial components released in inflamed periodontal tissues may be synergistically involved in periodontitis. The present study showed that human gingival fibroblasts mainly express histamine receptor H1R, and responded to histamine to produce interleukin (IL)-8. Stimulation of gingival fibroblasts with tumor necrosis factor-α, IL-1α, and lipopolysaccharide markedly induced IL-8 production, and the IL-8 production was synergistically augmented in the presence of or pre-treatment with histamine. Selective inhibitors of mitogen-activated protein kinases (MAPKs), nuclear factor (NF)-κB, and phospholipase C (PLC) significantly inhibited the synergistic effect. These results indicate that histamine induces IL-8 production from gingival fibroblasts through H1R, and synergistically augments the inflammatory stimuli by amplification of the MAPK and NF-κB through H1R-linked PLC.Abbreviations used: HDC, histidine decarboxylase; LPS, lipopolysaccharide; IL, interleukin; TNF, tumor necrosis factor; HR, histamine receptor; PLC, phospholipase C; MAPK, mitogen-activated protein kinase; NF, nuclear factor; ERK, extracellular signal-related kinase; JNK, c-Jun N-terminal kinase; R, receptor; TLR, Toll-like receptor; α-MEM, alpha-minimum essential medium; FCS, fetal calf serum; RT-PCR, reverse-transcriptase polymerase chain-reaction; ELISA, enzyme-linked immunosorbent assay; SD, standard deviation; LDH, lactate dehydrogenase.
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