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181.
Olefin Recovery by *BEA-Type Zeolite Membrane: Affinity-Based Separation with Olefin−Ag+ Interaction
Dr. Motomu Sakai Yuto Tsuzuki Naoyuki Fujimaki Prof. Masahiko Matsukata 《化学:亚洲杂志》2021,16(9):1101-1105
Ag+ was introduced into *BEA-type zeolite membrane by an ion-exchange method to enhance olefin selectivity. Ag−*BEA membrane exhibited superior olefin separation performance for both ethylene/ethane and propylene/propane mixtures. Particularly, the separation factor for ethylene at 373 K reached 57 with the ethylene permeance of 1.6×10−7 mol m−2 s−1 Pa−1. Adsorption properties of olefin and paraffin were evaluated to discuss contribution of Ag+ to separation performance enhancement. A strong interaction between olefin and Ag+ in the membrane caused preferential adsorption of olefin against paraffin, leading to selective permeation of olefin. Ag−*BEA membrane also exhibited high olefin selectivities from olefin/N2 mixtures. The affinity-based separation through Ag−*BEA membrane showed a high potential for olefin recovery and purification from various gas mixtures. 相似文献
182.
Perfluoroalkyl and ‐aryl Zinc Ate Complexes: Generation,Reactivity, and Synthetic Application
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Dr. Xuan Wang Dr. Keiichi Hirano Daisuke Kurauchi Hisano Kato Naoyuki Toriumi Dr. Ryo Takita Prof. Dr. Masanobu Uchiyama 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(31):10993-10996
A combination of dimethylzinc, perfluoroalkyl iodide, and LiCl afforded a new type of perfluoroalkyl (RF) zinc ate complex. These complexes show much greater thermal stability than conventional perfluorinated metal species, such as RF–lithium species and Grignard reagents, and they can be used at room temperature or higher. The results of DFT calculations on the origin of the enhanced stability are reported and the synthetic utility of RF‐zincate complexes is demonstrated. 相似文献
183.
A tandem catalytic asymmetric aldol reaction/cyclization of β,γ-didehydro-γ-lactones with aldehydes was achieved using chiral tin dibromide as a chiral precatalyst and sodium alkoxide as a base precatalyst. Optically active trans-β,γ-disubstituted γ-butyrolactones were selectively obtained in moderate to high yields with up to 99% ee from γ-aryl-substituted β,γ-didehydro-γ-butyrolactones and bulky aliphatic aldehydes. 相似文献
184.
A stereoselective synthesis of the core structure of cortistatin A (1), a novel antiangiogenic steroidal alkaloid from Indonesian marine sponge, is described. An 8-oxabicyclo[3.2.1]octene system, a characteristic B-ring structure of 1, was elaborated by a 7-endo selective intramolecular Heck cyclization and a subsequent acid-mediated oxy-Michael reaction. 相似文献
185.
Naoyuki Kotoku Shinichi FujiokaChiaki Nakata Masaki YamadaYuji Sumii Takashi KawachiMasayoshi Arai Motomasa Kobayashi 《Tetrahedron》2011,67(35):6673-6678
Structure-activity relationship of furospinosulin-1 (1), a hypoxia-selective growth inhibitor isolated from marine sponge, was investigated. Concise synthetic method of 1 was developed, and some structurally modified analogues were prepared. Biological evaluation of them revealed that the whole chemical structure was important for the hypoxia-selective growth inhibitory activity of 1. Among prepared, the desmethyl analogue 30 showed excellent hypoxia-selective inhibitory activity similar to that of 1 and also exhibited in vivo anti-tumor activity with oral administration. 相似文献
186.
187.
Risako Onodera Keiichi Motoyama Hidetoshi Arima 《Journal of inclusion phenomena and macrocyclic chemistry》2011,70(3-4):321-326
Methyl-??-cyclodextrin (M-??-CyD) is widely used as a raft disrupting agent through extraction of cholesterol from lipid rafts which are highly expressed in cell membranes of tumor cells, but it does not have tumor cell-selective action. Meanwhile, the widespread use of folic acid (FA) as a tumor-targeting ligand has been known, because folate receptor (FR) overexpresses in various kinds of epithelial tumor cells. In the present study, in order to obtain more tumor cell-selectivity and antitumor activity of M-??-CyD, we designed folate-appended M-??-CyD (FA-M-??-CyD), and evaluated its physicochemical properties and antitumor activity. The 1H-NMR study demonstrated that FA-M-??-CyD having average degree of substitution of FA (DSF) of 1.0 was prepared. In addition, FA-M-??-CyD (DSF 1.0) was found to be amorphous in a solid state and surface-active. Importantly, FA-M-??-CyD (DSF 1.0) had potent cytotoxicity, compared to M-??-CyD in KB cells, but not in A549 cells. These results suggest that FA-M-??-CyD (DSF 1.0) has the potential as a novel antitumor agent. 相似文献
188.
The effects of the substitution of fluoride ions for oxide ions on the thermal and optical properties of ternary ZnO-Bi2O3-P2O5 glass with low-P2O5 content (20-25 mol%) were investigated. Fluoride ions were introduced into the glass up to about 12 mol% as ZnF2. Raman spectra indicated that fluoride ions were substituted for oxide ions connected with bismuth ions. Deformation and glass transition temperatures decreased monotonically with fluorine concentration. The absorption edge shifted toward higher energies with increasing fluorine concentration by about 0.3 eV for 12 mol% ZnF2 substitution. The blue shift of the absorption edge is attributable to two effects. One was a blue shift of an absorption band which was observed as a peak at 4.7 eV in the reflection spectra and was attributed to the spin forbidden 6s-6p interband transition in Bi3+ ions. The blue shift originates from a change in electron-donating ability through anions as expected from electronegativity or optical basicity. Another is a disappearance of a shoulder at around 4.3 eV in the reflection spectra. The latter was the major reason for the large blue shift of the absorption edge energy, because the band relating to the 4.3 eV shoulder is close to the absorption edge. 相似文献
189.
Kashiwagi T Yamada N Hirayama K Suzuki C Kashiwagi Y Tsuchiya F Arata Y Kunishima N Morikawa K 《Journal of the American Society for Mass Spectrometry》2000,11(1):54-61
Electrospray ionization mass spectrometry (ESI-MS) was applied to the analysis of the dissociation and denaturation processes of a heterodimeric yeast killer toxin SMKT. The two distinct subunits of SMKT noncovalently associate under acidic conditions, but become dissociated and denatured under neutral and basic conditions. In order to understand the unique pH-dependent denaturation mechanism of this protein, a pH titration was performed by utilizing ESI-MS. The molecular ions of the heterodimer which possesses the highly ordered structure, were mainly observed below pH 4.6. However, the two subunits immediately dissociated at this pH. The spectra measured with various settings of the mass spectrometer indirectly demonstrated that the pH-dependent dissociation occurs in the liquid phase. The current result as well as the three-dimensional structure of SMKT suggest that the deprotonation of a specific carboxyl group triggers a cooperative dissociation process of this protein. In conclusion, the pH titration of a protein by ESI-MS is particularly effective, when the unfolding process or the biological function of the protein is related to the interaction with other molecules. 相似文献
190.
An analogue of the Dedekind–Rademacher sum and certain ray class invariants of real quadratic fields
Kazuhiro Onodera 《Journal of Number Theory》2013,133(6):1907-1931
In this paper, we consider a certain product of double sine functions as an analogue of the Dedekind–Rademacher sum. Its reciprocity formulas are established by decomposition of a certain double zeta function. As their applications, we reconstruct and refine a part of Arakawa?s work on ray class invariants of real quadratic fields, and prove directly explicit relations between various invariants which are defined in terms of the double sine function and are related to the Stark–Shintani conjecture. Moreover, in some examples, new expressions of the invariants are revealed. As two appendices, we give a new proof of Carlitz?s three-term relation for the Dedekind–Rademacher sum and a simple proof of Arakawa?s transformation formula for an analogue of the generalized Eisenstein series originated with Lewittes. 相似文献