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41.
Using elastic recoil detection analysis and low energy electron diffraction we have investigated the adsorption process of hydrogen on the
surface. We find that (1) room temperature adsorption of atomic hydrogen induces a structure transformation from the
to Si(111)-1 × 1-Ag(H) structures, (2) a saturation coverage of hydrogen is 1.5 monolayer, which almost coincides with the one on a clean 7 × 7 surface, and (3) thermal desorption of hydrogen from the ordered 1 × 1-Ag(H) surface results in the recovery of the original
surface. 相似文献
42.
Hiroki Hirai Kiichi Nakajima Soichiro Nakatsuka Kazushi Shiren Jingping Ni Shintaro Nomura Toshiaki Ikuta Takuji Hatakeyama 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2015,127(46):13785-13789
The development of a one‐step borylation of 1,3‐diaryloxybenzenes, yielding novel boron‐containing polycyclic aromatic compounds, is reported. The resulting boron‐containing compounds possess high singlet‐triplet excitation energies as a result of localized frontier molecular orbitals induced by boron and oxygen. Using these compounds as a host material, we successfully prepared phosphorescent organic light‐emitting diodes exhibiting high efficiency and adequate lifetimes. Moreover, using the present one‐step borylation, we succeeded in the synthesis of an efficient, thermally activated delayed fluorescence emitter and boron‐fused benzo[6]helicene. 相似文献
43.
Nakajima H Itoh K Otake H Fujimoto K 《Journal of photochemistry and photobiology. B, Biology》2011,104(3):467-472
To determine the characteristics of a Cu-hyperaccumulating moss Scopelophilacataractae and the influence of Cu on its structure and on chlorophyll (Chl), we measured reflectance and fluorescence (FL) spectra of S.cataractae samples with different Cu concentrations before and after wetting and the absorption spectra of Chl extracted from these samples. We found relationships between the spectral properties and Cu concentration. These relationships can be explained as follows. The higher the Cu concentration is, the lower is the plasticity of the cell wall, and the smaller is the increase in illuminated area due to the opening of the leaves after wetting. This results in a smaller increase in absorption and smaller decrease in reabsorption of the FL by Chl itself, and accordingly, a smaller increase in the FL band of Chl after wetting. Moreover, we found that the Chl concentration in S.cataractae is much higher than that in other common mosses and is correlated with an increase in the FL band of Chl after wetting. The remarkable increase in FL seen in S.cataractae and the slight increase in FL observed in other common mosses after wetting can be explained based on these findings. 相似文献
44.
Ogawa T Hattori H Kaneko R Ito K Iwai M Mizutani Y Arinobu T Ishii A Seno H 《Analytical and bioanalytical chemistry》2011,400(7):1959-1965
In this report, a high-throughput and sensitive method for analysis of eight central-acting muscle relaxants in human plasma
by ultra-performance liquid chromatography–tandem mass spectrometry (UPLC-MS/MS) in the positive and negative ionization modes
using tolbutamide as internal standard is presented. After pretreatment of a plasma sample by solid-phase extraction with
an Oasis HLB cartridge, muscle relaxants were analyzed by UPLC with Acquity UPLC BEH C18 column and Acquity TQD tandem quadrupole mass spectrometer equipped with an electrospray ionization interface. The calibration
curves for muscle relaxants spiked into human plasma equally showed good linearities in the nanogram per milliliter order
range. The detection limits (signal-to-noise ratio = 3) was as low as 0.1–2 ng/mL. The method gave satisfactory recovery rates,
accuracy, and precision for quality control samples spiked with muscle relaxants. To further validate the present method,
250 mg of chlorphenesin carbamate was orally administered to a healthy male volunteer, and the concentrations of chlorphenesin
carbamate in plasma were measured 0.5, 1, 2, 4, 6, and 8 h after dosing; their concentrations in human plasma were between
0.62 and 2.44 μg/mL. To our knowledge, this is the first report describing simultaneous analysis of over more than two central-acting
muscle relaxants by liquid chromatography–tandem mass spectrometry. This has been realized by the capability of our instrument
for simultaneous multiple reaction monitoring of the target compounds in both positive and negative ionization modes. Therefore,
the present method seems very useful in forensic and clinical toxicology and pharmacokinetic studies. 相似文献
45.
Hideki Miyaji Takanao Asahi Yoshihisa Miyamoto Kenjiro Asai 《Journal of Polymer Science.Polymer Physics》1987,25(1):159-171
Lattice constants of the monoclinic form of polyethylene under pressures up to 1.8 GPa at 298 K are investigated by x-ray diffraction. The thermal expansion from 100 K to 300 K at atmospheric pressure is also studied. The equation of state is calculated by Pastine's method, taking into account the zero-point vibration, and is compared with experimental results. The calculated results depend largely on the interatomic potential used and the limit of the interatomic distance for summation of the potentials. A change in the angle γ between the a and b axes results in an anisotropic change in the unit cell dimension with both pressure and temperature; the a and b axes change at nearly the same rate. The monoclinic form may have a higher density than the orthorhombic form at pressures above 1.0 GPa. 相似文献
46.
Secondary amines react with carbon disulphide to form stable dialkyldithiocarbamates at high pH in aqueous Triton X-100 solution. The formation rates of dimethyl-, diethyl-, di-n-propyl-, diisopropyl-, di-n-butyl- and diisobutyldithiocarbamates and pyrrolidinedithiocarbamate were measured by a stopped-flow spectrophotometric method. The reaction rates were a function of the pH of the solution and depended on the size and structure of the amines. The rate of isoalkylamines was far slower than that of the n-alkyl analogues. Individual concentrations of amines were determined in a mixture of di-n- and diisopropylamine and in a mixture of diiso- and di-n-butylamine. 相似文献
47.
Shigeru Ikuta 《Chemical physics》1985,95(2):235-242
The most stable conformation of ion-molecule complexes involving a CO molecule were surveyed by the use of Hartree-Fock (HF) MO and third-order Moller-Plesset perturbation (MP3) methods with a 6–31G* basis set ion = H+, Li+, Na+, K+, Bc2+, Mg2+, and Ca2+. The MP3 level of theory reveals the ion-CO conformation in which the ion bonds to a carbon atom of CO to be the most stable; these MP3 results are contrary to the HF ones. Binding energies of ion-molecule complexes involving CO and N2 were computed; MP3 energies are in good agreement with the experimental ones. The computed binding energies of cation-N2 are about one-third of cation-NH3 due to the absence of dipole moment and the smaller polarizability of N2. The decrease in binding energy in cation-CO and -N2 complexes, with increasing cation size, is mainly caused by the decrease of the electrostatic and polarization stabilizations. 相似文献
48.
49.
Kenjiro Maginu 《Journal of Mathematical Analysis and Applications》1978,65(1):85-109
We assume that a constant voltage is applied across a sample of a Gunn diode of finite length. When a periodic boundary condition is assumed, the dynamical behavior of the electric field within the sample is described by a nonlinear integral-partial differential equation. By using this equation, we can study the waveform stability of a traveling high-field domain of solitary-wave type which plays an essential role in the Gunn effect. We obtain simple criteria which the sample length and the applied voltage must satisfy for the existence and stability of the high-field domain. The stability analysis is carried out by using Liapunov's second method. 相似文献
50.
The Ag induced superstructures on the Si(111) surface have been studied by low energy electron diffraction constant momentum transfer averaging (LEED/CMTA) technique. The vertical displacements of the atoms are determined from the analysis of the specularly reflected (00) beam intensities. Unexpected behavior of the Ag atoms is clarified: For the √3 × √3-Ag surface it is verified that the Ag atoms are embedded in the first double layer of Si, leading to a considerable rearrangement of the substrate. In contrast, for the 3 × 1-Ag surface, the Ag atoms are riding on the Si surface and the reconstruction of the substrate is small. 相似文献