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91.
Mitsuhiro Ebara Takao Aoyagi Kiyotaka Sakai Teruo Okano 《Journal of polymer science. Part A, Polymer chemistry》2001,39(3):335-342
Aqueous gel deswelling rates for copolymer hydrogels comprising N‐isopropylacrylamide (IPAAm) and 2‐carboxyisopropylacrylamide (CIPAAm) in response to increasing temperatures were investigated. Compared with pure IPAAm‐based gels, IPAAm–CIPAAm gels shrink very rapidly in response to small temperature increases across their lower critical solution temperature (their volume is reduced by five‐sixths within 60 s). Shrinking rates for these hydrogels increase with increasing CIPAAm content. In contrast, structurally analogous IPAAm–acrylic acid (AAc) copolymer gels lose their temperature sensitivity with the introduction of only a few mole percent of AAc. Additionally, deswelling rates of IPAAm–AAc gels decrease with increasing AAc content. These results indicate that IPAAm–CIPAAm copolymer gels behave distinctly from IPAAm–AAc systems even if both comonomers, CIPAAm and AAc, possess carboxylic acid groups. Thus, we propose that the sensitive deswelling behavior for IPAAm–CIPAAm gels results from strong hydrophobic chain aggregation maintained between network polymer chains due to the similar chemical structures of CIPAAm and IPAAm. This structural homology facilitates aggregation of chain isopropylamide groups for both IPAAm and CIPAAm sequences with increasing temperature. The incorporation of AAc, however, shows no structural homology to IPAAm, inhibiting chain aggregation and limiting collapse. A functionalized temperature‐sensitive poly(N‐isopropylacrylamide) hydrogel containing carboxylic acid groups is possible with CIPAAm, producing rapid and large volume changes in response to smaller temperature changes. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 335–342, 2001 相似文献
92.
93.
The zero‐viscosity limit for an initial boundary value problem of the linearized Navier‐Stokes equations of a compressible viscous fluid in the half‐plane is studied. By means of the asymptotic analysis with multiple scales, we first construct an approximate solution of the linearized problem of the Navier‐Stokes equations as the combination of inner and boundary expansions. Next, by carefully using the technique on energy methods, we show the pointwise estimates of the error term of the approximate solution, which readily yield the uniform stability result for the linearized Navier‐Stokes solution in the zero‐viscosity limit. © 1999 John Wiley & Sons, Inc. 相似文献
94.
Rena Haruki Hironori Kouno Masanori Hosoyamada Taku Ogawa Nobuhiro Yanai Nobuo Kimizuka 《化学:亚洲杂志》2019,14(10):1723-1728
Molecular self‐assembly is a powerful means to construct nanoscale materials with advanced photophysical properties. Although the protection of the photo‐excited states from oxygen quenching is a critical issue, it still has been in an early phase of development. In this work, we demonstrate that a simple and typical molecular design for aqueous supramolecular assembly, modification of the chromophoric unit with hydrophilic oligo(ethylene glycol) chains and hydrophobic alkyl chains, is effective to avoid oxygen quenching of triplet–triplet annihilation‐based photon upconversion (TTA‐UC). While a TTA‐UC emission is completely quenched when the donor and acceptor are molecularly dispersed in chloroform, their aqueous co‐assemblies exhibit a clear upconverted emission in air‐saturated water even under extremely low chromophore concentrations down to 40 μm . The generalization of this nano‐encapsulation approach offers new functions and applications using oxygen‐sensitive species for supramolecular chemistry. 相似文献
95.
Osamu Kurata Norihiko Iki Takahiro Inoue Takayuki Matsunuma Taku Tsujimura Hirohide Furutani Masato Kawano Keisuke Arai Ekenechukwu Chijioke Okafor Akihiro Hayakawa Hideaki Kobayashi 《Proceedings of the Combustion Institute》2019,37(4):4587-4595
Low-NOx NH3-air combustion power generation technology was developed by using a 50-kWe class micro gas-turbine system at the National Institute of Advanced Industrial Science and Technology (AIST), Japan, for the first time. Based on the global demand for carbon-free power generation as well as recent advances involving gas-turbine technologies, such as heat-regenerative cycles, rapid fuel mixing using strong swirling flows, and two-stage combustion with equivalence ratio control, we developed a low-NOx NH3-air non-premixed combustor for the gas-turbine system. Considering a previously performed numerical analysis, which proved that the NO reduction level depends on the equivalence ratio of the primary combustion zone in a NH3-air swirl burner, an experimental study using a combustor test rig was carried out. Results showed that eliminating air flow through primary dilution holes moves the point of the lowest NO emissions to the lesser fuel flow rate. Based on findings derived by using a test rig, a rich-lean low NOx combustor was newly manufactured for actual gas-turbine operations. As a result, the NH3 single fueled low-NOx combustion gas-turbine power generation using the rich-lean combustion concept succeeded over a wide range of power and rotational speeds, i.e., below 10–40 kWe and 75,000–80,000?rpm, respectively. The NO emissions were reduced to 337?ppm (16% O2), which was about one-third of that of the base system. Simultaneously, unburnt NH3 was reduced significantly, especially at the low electrical power output, which was indicative of the wider operating range with high combustion efficiency. In addition, N2O emissions, which have a large Global Warming Potential (GWP) of 298, were reduced significantly, thus demonstrating the potential of NH3 gas-turbine power generation with low environmental impacts. 相似文献
96.
Synthetic studies of two components of tubulysins, tubulin polymerization inhibitors are described. The highly stereoselective synthesis of tubuvaline methyl ester (2) was accomplished by 1,3-dipolar cycloaddition of nitrone d-6 and acrylic acid derivatives 7 as a key step. The synthesis of tubuphenylalanine (3) was conducted by an aldol reaction of a boron enolate of (S)-4-isopropyl-3-propionyl-2-oxazolidinone (13) with aldehyde 14, readily prepared from phenylalanine, followed by Barton deoxygenation under radical conditions. 相似文献
97.
98.
Ryoji Kobori Tomonori Ohba Takaomi Suzuki Taku Iiyama Sumio Ozeki Michio Inagaki Akihiro Nakamura Masato Kawai Hirofumi Kanoh Katsumi Kaneko 《Adsorption》2009,15(2):114-122
N2 adsorption isotherms of molecular sieve carbon were measured at 77 K and 303 K. The Ar adsorption isotherms of molecular
sieve carbon samples were also measured at 303 K. The grand canonical Monte Carlo (GCMC) simulation technique was applied
to calculate the N2 and Ar adsorption isotherms at 303 K using the ultramicropore volume determined by H2O adsorption. The comparative method of experimental and simulated isotherms of supercritical N2 and Ar at 303 K gave the width of the micropore mouth of the molecular sieve carbon, which can be applied to the ultramicropore
width determination for other noncrystalline porous solids. 相似文献
99.
Consider the stationary Navier–Stokes equations in a bounded domain whose boundary consists of multi-connected components.
We investigate the solvability under the general flux condition which implies that the total sum of the flux of the given
data on each component of the boundary is equal to zero. Based on our Helmholtz–Weyl decomposition, we prove existence of
solutions if the harmonic part of the solenoidal extension of the given boundary data is sufficiently small in L
3 compared with the viscosity constant.
Dedicated to Professor Giovanni P. Galdi on the occasion of his 60th birthday. 相似文献
100.
Aoyagi Y Takahashi Y Fukaya H Takeya K Aiyama R Matsuzaki T Hashimoto S Kurihara T 《Chemical & pharmaceutical bulletin》2006,54(11):1602-1604
Isetexane diterpene analogues were semisynthesized from demethylsalvicanol isolated from Perovskia abrotanoides (Labiatae). The structure and cytotoxic activity relationships (SAR) of the natural parent diterpene, demethylsalvicanol, and its semisynthetic analogues were studied by using P388 murine leukemia cells. 相似文献