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781.
782.
The piston-driven ultra rapid pressure swing adsorption (URPSA) equipment was developed and oxygen enrichment from air was examined as an example. The adsorbent bed is directly connected to the cylinder where a piston moves at high frequency. Thus pressurization and depressurization in the bed are driven by mechanical piston motion, which can achieve far more rapid cycles compared with the conventional pressure swing operation using valves. The cycle time is usually on the order of seconds or sub seconds. Oxygen enrichment from air up to about 60% or higher of oxygen concentration was achieved by small-scale equipment using zeolite 5A with a oxygen production capacity of 100 Nm3-product gas/m3-zeolite/hr, which is about ten times larger than those of commercialized PSAs for this purpose.A simplified numerical model describing the mass transfer taking place in URPSA was developed. The model could simulate fairly well the air separation characteristics in terms of oxygen concentration, oxygen production capacity and oxygen yield. The proposed model helps in the understanding of the basic nature of URPSA and possible applications. This novel PSA is promising as a compact yet high-capacity PSA to be utilized in a wide variety of applications. 相似文献
783.
H Oyama M Endoh M Yoneda M Matsuki A Satoh S Nishida M Horino 《Journal of chromatography. A》1985,338(1):71-78
A successful application of high-performance liquid chromatography for analysis of urinary C-peptide is described. Samples (1.0 ml of human urine) were first subjected to gel chromatography to remove interfering substances, and then applied to a reversed-phase column (LiChrosorb RP-18, 7 micron). The detection of C-peptide was performed using a highly specific radioimmunoassay. With the newly developed techniques, at least four forms of immunoreactive C-peptide were detected in human urine. One of these peptides was indistinguishable from authentic C-peptide. The present study has clearly demonstrated the heterogeneity of urinary C-peptide. 相似文献
784.
The magnetic phase transition of the amorphous ferromagnetic alloys Fe80P13C7, Fe70Cr10P13C7 and Fe70Ni10P13C7 has been investigated by magnetization and specific heat measurements. From the field dependence of the isothermal magnetization, the critical exponents and the Curie temperature (TC) of Fe80P13C7 were obtained to be β = 0.38 ± 0.02, γ = 1.30 ± 0.05, θ = 4.47 ± 0.05 and Tc = 586.55 ± 0.1°K. These exponents sufficiently satisfy the static scaling law. The specific heat of Fe80P13C7 showed an approximate logarithmic singularity at Tc. The specific heat from Fe70Ni10P13C7 shows fairly broad peak and the peak almost smears out for Fe70Cr10P13C7. 相似文献
785.
Sound localization can be controlled by using head related transfer functions (HRTFs), which are related to the size of the head, the ears and so on. Since HRTFs are characterized by source directions and subjects, it is necessary to conduct measurements in all directions for all subjects. However, such measurement is expensive and time-consuming. In this paper, we propose a simpler and more useful method that investigates the relationship between HRTFs and physical size by multiple regression analysis. The estimated HRTFs are evaluated by objective and subjective measures. For objective results, the average spectral distortion score is 4.0 dB in a bandwidth ranging from 0 to 8 kHz. Subjective results indicate no significant difference between the measured and the estimated HRTFs in that frequency range. These results support the hypothesis that the proposed method is effective for estimating HRTFs. 相似文献
786.
Takafumi Saito Kenshu Fujiwara Yusuke Sano Takuto Sato Yoshihiko Kondo Uichi Akiba Yusuke Ishigaki Ryo Katoono Takanori Suzuki 《Tetrahedron letters》2018,59(14):1372-1376
In our previously reported method for the construction of the IJKLM-ring of ciguatoxin 3C (CTX3C), the lengthy synthetic process for the intermediate C42–C52 (L-ring) segment was problematic. Therefore, a new and improved procedure for the C42–C52 segment, having modified protecting groups, was developed. The new route includes a chirality transferring Ireland-Claisen rearrangement for the construction of the vicinal dimethyl branching at C47–48, a one-pot cyclization process for the establishment of the stereocenters at C45 and C46 as well as the γ-hydroxy δ-lactone framework corresponding to the L-ring, and Brown’s asymmetric crotylboration for the installation of the stereocenters at C43 and C44. The new C42–C52 segment was successfully coupled with the previously reported C32–C41 (I-ring) segment to produce the IJKLM-ring. 相似文献
787.
788.
Jinseok Kim Juwon Oh Takanori Soya Tomoki Yoneda Seongchul Park Manho Lim Atsuhiro Osuka Dongho Kim 《Angewandte Chemie (International ed. in English)》2020,59(13):5129-5134
Expanded porphyrins with appropriate metalation provide an excellent opportunity to study excited‐state aromaticity. The coordinated metal allows the excited‐state aromaticity in the triplet state to be detected through the heavy‐atom effect, but other metalation effects on the excited‐state aromaticity were ambiguous. Herein, the excited‐state aromaticity of gold(III) hexaphyrins through the relaxation dynamics was revealed via electronic and vibrational spectroscopy. The SQ states of gold [26]‐ and [28]‐hexaphyrins showed interconvertible absorption and IR spectra with those of counterparts in the ground‐state, indicating aromaticity reversal. Furthermore, while the T1 states of gold [28]‐hexaphyrins also exhibited reversed aromaticity according to Baird's rule, the ligand‐to‐metal charge‐transfer state of gold [26]‐hexaphyrins contributed by the gold metal showed non‐aromatic features arising from the odd‐number of π‐electrons. 相似文献
789.
Dr. Yusuke Ishigaki Takumi Hashimoto Kazuma Sugawara Prof. Dr. Shuichi Suzuki Prof. Dr. Takanori Suzuki 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(16):6643-6646
Thermally switchable redox properties have been reported to be due to a change in the spin state of newly designed overcrowded ethylenes, which can adopt closed-shell folded and open-shell twisted forms. In this study, tetrathienylanthraquinodimethane derivatives were designed to be in thermal equilibrium between a more stable folded form and less stable but more donating twisted diradical in solution, so that the oxidation potential can be controlled by heating/cooling. This is the first example of a switching of redox properties based on a thermally equilibrated twisted diradical, which can be more readily oxidized to the twisted dication. 相似文献
790.
Takuya Shimajiri Prof. Dr. Takanori Suzuki Dr. Yusuke Ishigaki 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(49):22436-22441
Since carbon–carbon (C−C) covalent bonds are rigid and robust, the bond length is, in general, nearly constant and depends only on the bond order and hybrid orbitals. We report herein direct visualization of the reversible expansion and contraction of a C(sp3)−C(sp3) single bond by light and heat. This flexibility of a C−C bond was demonstrated by X-ray analysis and Raman spectroscopy of hexaphenylethane (HPE)-type hydrocarbons with two spiro-dibenzocycloheptatriene units, the intramolecular [2+2] photocyclization of which and thermal cleavage of the resulting cyclobutane ring both occur in a single-crystalline phase. The force constant of the contracted C−C bond is 1.6 times greater than that of the expanded bond. Since formation of the cyclobutane ring and contraction of the C−C bond lower the HOMO level by approximately 1 eV, the oxidative properties of these HPEs with a flexible C−C bond can be deactivated/activated by light/heat. 相似文献