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11.
Based on non-linear response in phase transition events exhibiting a sharp transmittance change, an intelligent chiral sensor capable of chirality amplification in aqueous media was designed and constructed as poly(N-isopropylacrylamide) having chiral pseudo-18-crown-6. Both sensitivity and selectivity of the sensor surmount the limitation due to the law of mass action. 相似文献
12.
Several kinds of liposomes were sterilized at 121 degrees C for 20 min. They tended to aggregate after heat sterilization (HS) in saline, while no aggregation was observed in an isotonized sugar or polyol solution. The dispersions containing egg phosphatidylcholine (EggPC) with a high peroxide value (POV) turned slightly yellowish after HS. This color change was prevented by using EggPC with a low POV, hydrogenated EggPC (H-EggPC) or dipalmitoylphosphatidylcholine (DPPC). Nitrogen gas bubbling at neutral pH also prevented the color change, but vitamin E did not. The particle size of the EggPC liposomes extruded through a 0.4 micron membrane filter did not change significantly after HS, whereas the H-EggPC or DPPC liposomes extruded through a 0.8 micron membrane filter tended to be reduced in size. On this change the type of medium had a considerable influence. The anionic 6-carboxyfluorescein leaked from the negatively charged liposomes (EggPC/cholesterol (Chol)/egg phosphatidylglycerol) during HS, while no leakage was observed from the positively charged liposomes (EggPC/Chol/stearylamine) not only during HS but also during a long period of storage. It was suggested that sterilization of liposomes by heating was practicable as well as that by filtration, if the liposomes were prepared as follows: the charged liposomes made of lipids with low POV's were dispersed in a sugar or polyol solution adjusted to nearly pH 6.5, where the amount of dissolved oxygen was minimized. An ionic water-soluble drug had to be encapsulated in the oppositely charged liposomes. 相似文献
13.
Ueno Y Tate A Niwa O Zhou HS Yamada T Honma I 《Analytical and bioanalytical chemistry》2005,382(3):804-809
The gas selectivities of highly ordered mesoporous silicates and commercially-obtained porous silicates with respect to benzene, toluene and xylene were studied. After studying the porosities, pore uniformities, and surface silanol structures of the silicates and their relationships to gas selectivity in detail, we found that we could achieve high benzene selectivity by controlling the micropore size (less than 1 nm). Concluding that mesoporous silicate has a suitable micropore size and structure for benzene selectivity, we also observed that mesoporous silicate SBA-16 exhibited a high (>6) benzene selectivity from toluene and xylene even in a pseudo-atmospheric environment. A benzene detection limit of about 100 ppb was achieved by introducing SBA-16 into a microfluidic device originally developed for the separate detection of benzene, toluene, and xylene gases. 相似文献
14.
[reaction: see text] A new strategy directed toward the total synthesis of stachyflin, a potent and novel anti-influenza A virus agent isolated from a microorganism, has been presented through the enantioselective synthesis of the tetracyclic core structure. The synthetic method features a BF(3) x Et(2)O-induced domino epoxide-opening/rearrangement/cyclization reaction as the key step. 相似文献
15.
Mitsutoshi Kimura Akiyuki Iwata Masahiro Itoh Kazuki Yamada Tsutomu Kimura Noriyuki Sugiura Masaru Ishida Shinzi Kato 《Helvetica chimica acta》2006,89(4):747-783
A series of [(thioacyl)thio]‐ and (acylseleno)antimony and [(thioacyl)thio]‐ and (acylseleno)bismuth, i.e., (RCSS)xMR and (RCOSe)xMR (M = Sb, Bi, R1 = aryl, x = 1–3), were synthesized in moderate to good yields by treating piperidinium or sodium carbodithioates and ‐selenoates with antimony and bismuth halides. Crystal structures of (4‐MeC6H4CSS)2Sb(4‐MeC6H4) ( 9b′ ), (4‐MeOC6H4COSe)2Sb(4‐MeC6H4) ( 12c′ ), (4‐MeOC6H4COS)2Bi(4‐MeC6H4) ( 15c′ ), and (4‐MeOC6H4CSS)2BiPh ( 18c ) along with (4‐MeC6H4COS)2SbPh ( 6b ) and (4‐MeC6H4COS)3Sb ( 7b ) were determined (Figs. 1 and 2). These compounds have a distorted square pyramidal structure, where the aryl or carbothioato (= acylthio) ligand at the central Sb‐ or Bi‐atom is perpendicular to the plane that includes the two carbodithioato (= (thioacyl)thio), carboselenato (= acylseleno), or carbothioato ligand and exist as an enantiomorph pair. Despite the large atomic radii, the C?S ??? Sb distances in (RCSS)2MR1 (M = As, Sb, Bi; R1 = aryl) and the C?O ??? Sb distances in (RCOS)xMR (M = As, Sb, Bi; x = 2, 3) are comparable to or shorter than those of the corresponding arsenic derivatives (Tables 2 and 3). A molecular‐orbital calculation performed on the model compounds (MeC(E)E1)3?xMMex (M = As, Sb, Bi; E = O, S; E1 = S, Se; x = 1, 2) at the RHF/LANL2DZ level supported this shortening of C?E ??? Sb distances (Table 4). Natural‐bond‐orbital (NBO) analyses of the model compounds also revealed that two types of orbital interactions nS → σ and nS → σ play a role in the (thioacyl)thio derivatives (MeCSS)3?xMMex (x = 1, 2) (Table 5). In the acylthio‐MeCOSMMe2 (M = As, Sb, Bi), nO → σ contributes predominantly to the orbital interactions, but in MeCOSeSbMe2, none of nO → σ and nO → σ contributes to the orbital interactions. The nS → σ and nS → σ orbital interactions in the (thioacyl)thio derivatives are greater than those of nO → σ and nO → σ in the acylthio and acylseleno derivatives (MeCOE)3?xMMex (E = S, Se; M = As, Sb, Bi; x = 1, 2). ?The reactions of RCOSeSbPh2 (R = 4‐MeC6H4) with piperidine led to the formation of piperidinium diphenylselenoxoantimonate(1?) (= piperidinium diphenylstibinoselenoite) (H2NC5H10)+Ph2SbSe?, along with the corresponding N‐acylpiperidine (Table 6). Similar reactions of the bis‐derivatives (RCOSe)2SbR1 (R, R1 = 4‐MeC6H4) with piperidine gave the novel di(piperidinium) phenyldiselenoxoantimonate(2?) (= di(piperidinium) phenylstibonodiselenoite), [(H2NC5H10)+]2(PhSbSe2)2?, in which the negative charges are delocalized on the SbSe2 moiety (Table 6). Treatment of RCOSeSbR (R, R1 = 4‐MeC6H4) with N‐halosuccinimides indicated the formation of Se‐(halocyclohexyl) arenecarboselenoates (Table 8). Pyrolysis of bis(acylseleno)arylbismuth at 150° gave Se‐aryl carboselenoates in moderate to good yields (Table 9). 相似文献
16.
Tamao Ishida Yuta Onuma Kota Kinjo Akiyuki Hamasaki Hironori Ohashi Tetsuo Honma Tomoki Akita Takushi Yokoyama Makoto Tokunaga Masatake Haruta 《Tetrahedron》2014
Palladium nanoparticles (Pd NPs) encapsulated by conjugated microporous polymers (CMPs) were prepared by the Pd-catalyzed polymerization followed by a thermal treatment with N2 or H2. The Pd catalysts were embedded in the porous network during polymerization and used as a precursor for the generation of Pd NPs in CMP. Although no Pd NPs were formed in the as-synthesized Pd/CMPs, Pd NPs with 1.6–3.5 nm size were formed after the thermal treatment. The obtained Pd/CMP-N2 and -H2 catalysts were highly selective in the hydrogenation of 4-nitrostyrene to 4-ethylnitrobenzene, whereas Pd NPs supported on carbon (Ketjen black) gave a fully reduced product, 4-ethylaniline. Substituents in CMP framework could change the catalytic activity of Pd NPs; hydroxy-substituted CMP encapsulated Pd NPs showed higher catalytic activity than Pd/CMP-H2 for benzyl alcohol oxidation. 相似文献
17.
Akiyuki Takahashi Nasr M. Ghoniem 《Journal of the mechanics and physics of solids》2008,56(4):1534-1553
A new computational method for the elastic interaction between dislocations and precipitates is developed and applied to the solution of problems involving dislocation cutting and looping around precipitates. Based on the superposition principle, the solution to the dislocation-precipitate interaction problem is obtained as the sum of two solutions: (1) a dislocation problem with image stresses from interfaces between the dislocation and the precipitate, and (2) a correction solution for the elastic problem of a precipitate with an initial strain distribution. The current development is based on a combination of the parametric dislocation dynamics (PDD) and the boundary element method (BEM) with volume integrals.The method allows us to calculate the stress field both inside and outside precipitates of elastic moduli different from the matrix, and that may have initial coherency strain fields. The numerical results of the present method show good convergence and high accuracy when compared to a known analytical solution, and they are also in good agreement with molecular dynamics (MD) simulations. Sheared copper precipitates (2.5 nm in diameter) are shown to lose some of their resistance to dislocation motion after they are cut by leading dislocations in a pileup. Successive cutting of precipitates by the passage of a dislocation pileup reduces the resistance to about half its original value, when the number of dislocations in the pileup exceeds about 10. The transition from the shearable precipitate regime to the Orowan looping regime occurs for precipitate-to-matrix elastic modulus ratios above approximately 3-4, with some dependence on the precipitate size. The effects of precipitate size, spacing, and elastic modulus mismatch with the host matrix on the critical shear stress (CSS) to dislocation motion are presented. 相似文献
18.
High benzene selectivity of uniform sub-nanometre pores of self-ordered mesoporous silicate 总被引:1,自引:0,他引:1
Ueno Y Tate A Niwa O Zhou HS Yamada T Honma I 《Chemical communications (Cambridge, England)》2004,(6):746-747
The high benzene gas selectivity of mesoporous silicate (SBA-15) was observed in the sub-nanometre micropore condensation region. The benzene/toluene ratios of the adsorbed amount were >100 and >6 in ideal and pseudo-atmospheric environments, respectively. 相似文献
19.
Yamamoto S Hisatomi O Hasegawa A Kobayashi Y Tokunaga F 《Photochemistry and photobiology》2007,83(1):35-39
Unlike other vertebrates, teleosts have rod- and cone-specific phosducins (PD-R and PD-C) in the retina. To evaluate the teleost Gbetagamma-PD systems, we isolated cDNAs encoding medaka Gbeta1 and GbetaC, which selectively expressed rods and cones. Immunohistochemical studies showed that the strong reactivity of GbetaC but not PD-C was detected in cone outer segments. In rod outer segments (ROS), PD-R reactivity was stronger in light-adapted retina than in dark-adapted retina. Western blot analyses of fractions torn from the cryosections showed that the PD-R concentration was low in dark-adapted ROS. It is suggested that PD-R is translocated to ROS and effectively downregulates the phototransduction cascade in light-adapted rods. 相似文献
20.
Chen WT Guo GC Wang MS Xu G Cai LZ Akitsu T Akita-Tanaka M Matsushita A Huang JS 《Inorganic chemistry》2007,46(6):2105-2114
Two structural series, including seven isomorphous heterodinuclear complexes, [Ln(DMSO)4(H2O)3(mu-CN)M(CN)5].H2O ([La-Fe] (1), [Pr-Fe] (2), [Pr-Co] (3), [Nd-Fe] (4), [Nd-Co] (5), [Sm-Fe] (6) and [Sm-Co] (7)), and seven isostructural 2-D stair-like cyano-bridged bimetallic assemblies, [Ln(DMSO)2(H2O)(mu-CN)4M(CN)2]n ([La-Fe]n (8), [Pr-Fe]n (9), [Pr-Co]n (10), [Nd-Fe]n (11), [Nd-Co]n (12), [Sm-Fe]n (13) and [Sm-Co]n (14)) (DMSO = dimethylsulfoxide), have been rationally prepared by a facile approach, a ball-milling method, and characterized by X-ray diffraction and magnetic measurements. The isomorphous structures, in conjunction with the diamagnetism of the Co(3+) and La(3+) ions, allow an approximation to the nature of coupling between the iron(III) and lanthanide(III) ions in the Ln(3+)-Fe(3+) complexes. The Ln(3+)-Fe(3+) interaction is ferromagnetic for the dinuclear [Pr-Fe] (2), [Nd-Fe] (4), and [Sm-Fe] (6) systems and for the 2-D [Pr-Fe]n (9), [Nd-Fe]n (11), and [Sm-Fe]n (13) assemblies. 相似文献