Search Results - (Author, Cooperation:T. Oka)

2015-03-21

American Association for the Advancement of Science (AAAS)

0036-8075

1095-9203

Biology

Chemistry and Pharmacology

Computer Science

Medicine

Natural Sciences in General

Physics

2014-05-03

American Association for the Advancement of Science (AAAS)

0036-8075

1095-9203

Biology

Chemistry and Pharmacology

Computer Science

Medicine

Natural Sciences in General

Physics

2011-01-22

American Association for the Advancement of Science (AAAS)

0036-8075

1095-9203

Biology

Chemistry and Pharmacology

Computer Science

Medicine

Natural Sciences in General

Physics

2012-04-27

Nature Publishing Group (NPG)

0028-0836

1476-4687

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

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2018-11-02

American Society of Hematology (ASH)

0006-4971

1528-0020

Biology

Medicine

Immunobiology and Immunotherapy, Lymphoid Neoplasia

1089-7690

AIP Digital Archive

Physics

Chemistry and Pharmacology

The double resonance technique has been applied to a molecular ion. We have observed microwave-infrared double resonance signals of HN+2 produced in a hollow cathode discharge at low pressures (20–200 mTorr). A color center laser with 2–20 mWatts of power provided the infrared signal radiation, and a millimeter wave klystron with ∼400 mWatts of power provided the microwave pump radiation. The frequency of the microwave radiation was swept and the double resonance signal was detected through variation of the infrared power. Using the R(1) and P(1)infrared transitions we have observed the J=1←0 rotational transition in both the ground state and the ν1 state. We have observed not only the direct three-level double resonance signals, but also collision-induced four-level double resonance signals indicating the existence of some selection rules for the Langevin potential dominated ion–neutral interaction. The major results of this paper are: (1) The double resonance method is now applicable to molecular ions and (2) ion–molecule collisions have selection rules.

Electronic Resource

1089-7690

AIP Digital Archive

Physics

Chemistry and Pharmacology

We have investigated collision-induced rotational transitions of HN+2 and HCN using infrared-microwave four-level double resonance spectroscopy. These two isoelectronic molecules were studied in collisions with He, Ar, and N2. For all cases studied, we have observed that the collision-induced rotational transitions exhibit collisional "selection rules.'' The selection rules can be explained using the symmetry properties (i.e., parity) of the dominant terms in the interaction potential. This represents the first observation of selection rules for rotational energy transfer of a molecular ion. This study has allowed us to directly compare the difference between ion–neutral and neutral–neutral collisions which cause rotational transitions. We have experimentally observed that ion–neutral and neutral–neutral collisions differ because of the presence of the Langevin force in the ion–neutral interaction potential, which has two unique effects. The Langevin force produces a charge-induced dipole in the collision partner which is parallel to the ion's electric field. This charge-induced dipole interacts with the electric charge of the molecular ion which creates an attractive force between the ion and neutral. This interaction therefore decreases the ion–neutral distance and produces strong collisions which randomizes the rotational states. The second effect occurs when the molecular ion has a permanent electric moment. The charge-induced dipole in the collision partner will interact with an electric moment of the molecular ion creating a long-range interaction. For HN+2, a molecular ion with a permanent dipole moment, this interaction produces "dipole-type'' collisional selection rules.

Electronic Resource

1089-7690

AIP Digital Archive

Physics

Chemistry and Pharmacology

Infrared–microwave double resonance spectroscopy has been used to study the simple molecular ion HN+2. This is the first application of this powerful method to a molecular ion. The HN+2 ion was produced in a hollow cathode discharge cell, which served two purposes. First, the hollow cathode discharge is capable of producing relatively large concentrations of ions at the low pressures required for saturation. Also, the hollow cathode serves as a waveguide for the propagation of the microwave radiation. A color center laser was used as the infrared source. Its high power was essential in this work for saturation of the infrared transitions. The HN+2 ion was chosen as a test case for double resonance because of the availability of detailed spectroscopic information and its ease of production. We have observed the pure rotational transition J=1←0 in both the ground and ν1 states using the ν1 infrared fundamental. The determined molecular constants are eqQ=−5.88(10) MHz and B=46 586.895(18) MHz for the ground state, and eqQ=−5.71(17) MHz and B=46 208.986(27) MHz for the ν1 state. The high sensitivity of the double resonance technique has also allowed us to study the direct l-type doubling transitions in the ν2 and ν1+ν2 states using the ν1+ν2←ν2 infrared hot band. To the best of our knowledge, this is the first centimeter wave spectrum of a molecular ion. The determined molecular constants are q=254.966(11) MHz and qJ =−2.83(17) kHz for the ν2 state, and q=258.912(32) MHz and qJ =−3.15(65) kHz for the ν1+ν2 state.

Electronic Resource

1089-7690

AIP Digital Archive

Physics

Chemistry and Pharmacology

The ν3 degenerate vibration–rotation band of the ammonia cation NH+3 was observed and analyzed. The spectrum was detected in direct absorption using a tunable difference frequency spectrometer combined with velocity modulation. The ion was produced in a 6 kHz ac discharge with a gas mixture of He:H2:NH3 (∼250:8:1) and with a total pressure of ∼6 Torr. Spin–rotation splittings for most Q-branch transitions were well resolved and spin–rotation interaction constants were determined. A symmetric rotor Hamiltonian with A1–A2 splittings and l resonance was used to analyze the spectrum. The spectral pattern indicates that NH+3 is a planar molecular with D3h symmetry, consistent with a 2A‘2 ground electronic state.

Electronic Resource

1089-7690

AIP Digital Archive

Physics

Chemistry and Pharmacology

The (2ν2,l=2←ν2), (2ν2,l=0←ν2), and (ν1+ν2←ν1) hot bands of H+3 were observed. The vibrationally hot ions were produced in a liquid nitrogen cooled 6 kHz ac discharge using gas mixtures of H2 and He. The spectra were detected in direct absorption using a newly extended tunable difference frequency spectrometer using both LiNbO3 and LiIO3 crystals as nonlinear optical elements. The range of this spectrometer is now ∼5300–∼1900 cm−1. The positions of the rovibrational transitions compare extremely well with the theoretical predictions of Miller and Tennyson. A vibrational temperature study of the discharge indicates a significant population inversion between the ν1 and ν2 levels.

Electronic Resource

1089-7690

AIP Digital Archive

Physics

Chemistry and Pharmacology

The ν3 band of NH+2 in the X˜ 3B1 ground electronic state was observed in direct absorption with a tunable difference frequency laser spectrometer in the 3 μ region, using velocity modulation detection. NH+2 and NH+3 ions were generated in an ac discharge of He and NH3, or of He, N2, and H2. Fifty-three rovibrational transitions were measured and fit to a triplet A-reduced Hamiltonian to determine rotational, centrifugal distortion, and spin–rotation constants. The band origin was found to be ν0=3359.932 cm−1, in excellent agreement with a recent calculation of Jensen, Bunker, and McLean. Indirect evidence from the spectrum suggested that NH+2 is quasilinear, but selection rules prevented a determination of the A rotational constant.

Electronic Resource

1089-7623

AIP Digital Archive

Physics

Electrical Engineering, Measurement and Control Technology

A fast response calorimeter has been developed for the neutral-beam (NB) shine-through measurement. This calorimeter has the following advantages. (1) Temporal variation of the heat load onto the calorimeter can be measured. (2) Measurement under the relatively high heat flux environment is possible. (3) The calorimetric measurement under continuous and steady-state heat load environment is also possible. The verification of the measurement principle was done using an NB-injection system on the compact helical system (CHS) at the National Institute for Fusion Science (NIFS). The measured NB power densities are compared to the power densities being evaluated by the CHS-NB profile database. It was experimentally confirmed that the time constant of the measurement is about 7 ms. © 2001 American Institute of Physics.

Electronic Resource

1089-7690

AIP Digital Archive

Physics

Chemistry and Pharmacology

The spectrum of the 5g–4f inter-Rydberg band of H2 has been recorded with a difference frequency laser system and analyzed using multichannel quantum defect theory (MQDT). New transitions have been observed; in addition to the singlet–triplet splittings previously observed, the hyperfine structure of the ortho-hydrogen spectrum is partially resolved in the present experiment. MQDT is used to analyze the data in a two stage process. First, the ab initio MQDT predictions were refined by fitting the quantum defect functions over a range of internuclear separation R. Second, 4f singlet and triplet quantum defects are extracted from the para-hydrogen spectra, i.e., those lines without complicating hyperfine structure. This information was then used to calculate the fine structure of a sample ortho-hydrogen line, R3(2)v+=0. While the spectra are predominantly composed of absorption lines, some transitions from high vibrational levels of the 5g triplet manifold to 4f triplet levels are observed in stimulated emission. © 2000 American Institute of Physics.

Electronic Resource

1089-7690

AIP Digital Archive

Physics

Chemistry and Pharmacology

We present experimental evidence for nuclear spin selection rules in chemical reactions that have been theoretically anticipated by Quack [M. Quack, Mol. Phys. 34, 477 (1997)]. The abundance ratio of ortho-H3+ (I=3/2) and para-H3+ (I=1/2), R=[o-H3+]/[p-H3+], has been measured from relative intensities of their infrared spectral lines in hydrogen plasmas using para-H2 and normal-H2 (75% o-H2 and 25% p-H2). The observed clear differences in the value of R between the p-H2 and n-H2 plasmas demonstrate the spin memory of protons even after ion-neutral reactions, and thus the existence of selection rules for spin modifications. Both positive column discharges and hollow cathode discharges have been used to demonstrate the effect. Experiments using pulsed plasmas have been conducted in the hollow cathode to minimize the uncertainty due to long-term conversion between p-H2 and o-H2 and to study the time dependence of the o-H3+ to p-H3+ ratio. The observed R(t) has been analyzed using simultaneous rate equations assuming the nuclear spin branching ratios calculated from Quack's theory. In p-H2 plasmas, the electron impact ionization followed by the ion-neutral reaction H2++H2→H3++H produces pure p-H3+, but the subsequent reaction between p-H3+ and p-H2 scrambles protons. While the proton hop reaction (rate constant kH) maintains the purity of p-H3+, the hydrogen exchange reaction (rate constant kE) produces o-H3+ and acts as the gateway for nuclear spin conversion. The value of R(t), therefore, depends critically on the ratio of their reaction rates α=kH/kE. From observed values of R(t), the ratio has been determined to be α=2.4. This is in approximate agreement with the value reported by Gerlich using isotopic species. © 2000 American Institute of Physics.

Electronic Resource

1089-7690

AIP Digital Archive

Physics

Chemistry and Pharmacology

A color center laser spectrometer along with velocity modulation detection was used to record the absorption spectrum of H2O+ produced in an AC glow discharge between 3180 and 3390 cm−1 with a gas mixture of He/H2O. The predominant role of the reaction of metastable helium with H2O has been observed. The H2O+ ion is also present in the spectra recorded between 3100 and 3600 cm−1 with a gas mixture of He/H2/O2 and some features are illustrated. The ν1 and ν2+ν3−ν2 bands have been assigned and the previous analysis of the ν3 band [J. Mol. Spectrosc. 127, 1 (1988)] has been extended. The ν1 and ν3 states have been fitted together taking into account the vibration–rotation interaction. The molecular constants have been obtained for the ν1 and ν2+ν3 states and they have been improved in the case of the ν3 and the ground vibrational states. The equilibrium structure has been derived [re=0.9992(6) A(ring), θe=109.30(10)°] and the quadratic and cubic force field constants have been evaluated.

Electronic Resource

1089-7690

AIP Digital Archive

Physics

Chemistry and Pharmacology

The fundamental v=1←0 vibration–rotation band of OD− has been observed using the tunable infrared radiation from a difference frequency laser system and the velocity modulation technique for detection. The band origin is determined to be 2625.332(3) cm−1. The rotational constant B and the centrifugal distortion constant D have been determined for both the ground state and the first excited state. A remarkable similarity between molecular constants of OD− and OD has been noticed and utilized to estimate equilibrium vibration–rotation constants. These vibration–rotation constants were used to estimate the equilibrium bond length and the quadratic, cubic, and quartic force constants.

Electronic Resource

1089-7690

AIP Digital Archive

Physics

Chemistry and Pharmacology

The observation of the high-resolution absorption spectrum of the H2D+ molecular ion in the region 2010–2610 cm−1 in discharges through mixtures of H2 and D2 gases is reported. Two types of tunable monochromatic sources are employed, either a diode laser (in Ottawa) or a difference-frequency laser system (in Chicago), and the sensitivity is improved by using either discharge modulation or Doppler velocity modulation techniques. A total of 66 new lines of H2D+ have been measured and assigned, mostly on the basis of ground-state combination differences, to specific rotational transitions of the ν2 and ν3 bands. These data, as well as the two known microwave lines, are fitted by means of two theoretical models, either an effective Hamiltonian model including a Padé representation of a conventional A-reduced centrifugal Hamiltonian for each vibrational level together with Coriolis and higher rotational interactions between ν2 and ν3, or a supermatrix model in which the matrix of the untransformed Hamiltonian is set up in a large vibration-rotation basis and diagonalized directly. In the supermatrix model most of the vibrationally off-diagonal matrix elements are constrained to values derived from Carney's ab initio calculations, while the ν1 parameters are fitted to the observed lines of Amano. Because of the large number of parameters required in the effective Hamiltonian, the less flexible supermatrix model was valuable as a check of the assignments. The results of these fits make it possible to assign seven of the nine lines reported by Shy, Farley, and Wing in 1981. The observed band origins, ν2=2205.87 cm−1 and ν3=2335.45 cm−1, as well as the rotational constants, are in good agreement with ab initio predictions. With the use of one calculated term value to relate the stacks of levels with even and odd values of K‘a, a table of observed term values of the lower rotational levels of the ground state and the ν2 and ν3 states is constructed.

Electronic Resource

1750-3841

Blackwell Publishing Journal Backfiles 1879-2005

Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Process Engineering, Biotechnology, Nutrition Technology

Free amino acids and related compounds in the nonprotein nitrogen (NPN) fraction of winged bean seeds and sprouts were quantitatively determined. The proportion of NPN to total nitrogen was low in the seeds (9%) and in the cotyledons of the sprouts (11%), and relatively high in the epicotyls of the sprouts (54%). About 6% and 40% NPN were attributable to free amino acid nitrogen in the seeds and the sprouts, respectively. The free amino acid profile of seeds was characterized by the presence of sizable amounts of γ-L-glutamyl-L-tyrosine and γ-L-glutamyl-L-phenylalanine, indicating similarities to that of soybean seeds. Accumulation of free amino acids, particularly nonprotein amino acids such as α-aminoadipic acid and γ-aminobutyric acid, were demonstrated in the sprouts. No canavanine was detected in either seeds or sprouts.

Electronic Resource

1600-0714

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Localization of IgA, secretory component (SC) and J chain was investigated immunocytochemically in minor salivary glands of the lip and palate to define the mechanism involved in the transport of immunoglobulin A (slgA) into the saliva from the minor salivary glands. SC synthesis was detected in mucous acinar cells and ductal epithelial cells. Free SC is secreted into the saliva through secretory granules in the mucous acinar cells. Dimeric IgA containing J chain is translocated through these cells as slgA by a SC-medialed transport mechanism involving cytoplasmic vesicles.

Electronic Resource

1365-2133

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

A case of cutaneous angiosarcoma occurring in a 51-year-old male renal transplant patient is reported. Multiple violaceous nodules surrounded by poorly demarcated red to purple discoloration were found on his scalp. Immunosuppressants consisting of azathioprine and prednisolone had been administered during the 12-year period since the renal transplantation. We diagnosed the lesion clinically as a cutaneous angiosarcoma and performed a wide surgical excision. The histopathological findings confirmed the diagnosis and showed tumour cells in the peripheral margin. Postoperatively, the patient started immunotherapy with systemic administration of recombinant interleukin-2 (rIL-2), but he refused to continue it because of the acute rejection of the transplanted kidney induced by the rIL-2. Instead he received radiation therapy (total 7000 rad) of the scalp. Although no recurrence was noticed for 15 months after the completion of radiation, he died due to lung metastasis from angiosarcoma. We review the seven cases, including ours, of angiosarcoma after renal transplantation that are reported in detail in the literature.

Electronic Resource