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排序方式: 共有266条查询结果,搜索用时 15 毫秒
1.
Formation of dityrosine and other fluorescent amino acids by reaction of amino acids with lipid hydroperoxides 总被引:7,自引:0,他引:7
Formation of fluorescence by the reaction of various amino acids with lipid hydroperoxides,i.e., linoleic acid 13-monohydroperoxide, methyl linoleate 13-monohydroperoxide and phosphatidylcholine hydroperoxide, in the
presence of methemoglobin was investigated. Two types of fluorescence were produced: fluorescent dityrosine (3,3′-dityrosine)
from tyrosine, and unidentified fluorophores with α- and ε-amino groups of various amino acids. While the former was stable
after treatment with borohydride, the latter fluorophores were readily destroyed. The rate of dityrosine formation was rapid,
and the yield of dityrosine was dependent on the concentrations of tyrosine and the lipid hydroperoxides. Butylated hydroxytoluene
and tocopherol inhibited the formation of dityrosine, but did not affect the formation of fluorophores on the amino groups.
Dityrosine appears to be formed by radical reaction of the lipid hydroperoxides, while the other fluorophores seem to be created
by nonradical mechanisms. 相似文献
2.
Takashi Hayashi Makoto Mihoya Iwao Yamai Hajime Saito Shin-Ichi Hirano 《Journal of Materials Science》1987,22(4):1305-1309
Needle-like or wool-like Al2O3 whiskers can be grown on a substrate by the hydrolysis of aluminium fluoride vapour. Effects of the growth conditions on the morphology of the crystals and growth processes of the whisker were investigated, and the optimum growth condition of whiskers was examined. Adequate vapour pressure conditions of the reactant gases for the growth of the wool-like whisker were found to be
. Aluminium oxyfluoride was assumed to be the most probable intermediate species for the growth of Al2O3 whiskers. A variety of crystal morphologies are also shown and described with respect to the experimental conditions. 相似文献
3.
Controlling the familywise error rate in functional neuroimaging: a comparative review 总被引:1,自引:0,他引:1
Functional neuroimaging data embodies a massive multiple testing problem, where 100,000 correlated test statistics must be assessed. The familywise error rate, the chance of any false positives is the standard measure of Type I errors in multiple testing. In this paper we review and evaluate three approaches to thresholding images of test statistics: Bonferroni, random field and the permutation test. Owing to recent developments, improved Bonferroni procedures, such as Hochberg's methods, are now applicable to dependent data. Continuous random field methods use the smoothness of the image to adapt to the severity of the multiple testing problem. Also, increased computing power has made both permutation and bootstrap methods applicable to functional neuroimaging. We evaluate these approaches on t images using simulations and a collection of real datasets. We find that Bonferroni-related tests offer little improvement over Bonferroni, while the permutation method offers substantial improvement over the random field method for low smoothness and low degrees of freedom. We also show the limitations of trying to find an equivalent number of independent tests for an image of correlated test statistics. 相似文献
4.
Composite films made of silk fibroin (SF) and polyallylamine (PAA) are prepared that contain various compositional ratios. These materials are analyzed to elucidate the resulting physical properties and to assess their potential toward advanced applications as industrial materials. The composite films are obtained from a SF and PAA binary system by dry casting from aqueous solution. These composite films exhibit excellent processability such as film forming capabilities, and the elongation at break is increased in the wet state. The differential scanning calorimetry (DSC) curves of the composites suggest that a mutual interaction takes place between the SF and PAA. This interaction is believed to occur because the endothermic peak, corresponding to the individual polymer, shifts with increasing SF content. The random coil conformation of the SF is present, regardless of the PAA blending, as confirmed by FTIR and DSC measurements. Additionally, living cells from Antheraea pernyi and Bombyx mori insect tissues are shown to grow effectively on the composite films. Maximum growth levels occur when the cultivation flask is coated with the material in SF/PAA ratios of 75:25 to 25:75. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1963–1970, 2002; DOI 10.1002/app.10491 相似文献
5.
A commericial sample of the oyster,Crassostrea virginica, obtained from Maryland waters of the Chesapeake Bay, contained 31 desmethylesterols and at least eight 4-monomethylsterols.
The combined gas liquid chromatography-mass spectra of the minor components showed the presence of 6 unusual sterols, 24-ethylcholest-22-en-3β
ol, 4α-methyl-24-ethylcholestan-3β-ol, occelasterol, (24E)-24-propylidene-cholest-5-en-3β-ol, (24ZO-24-propylidene-cholest-5-en-3β-ol,
and 24-methylene-cholestanol. The C-24 configuration of 24-ethylcholest-5-enol, 24-methyl-cholesta-5,22-dienol, and 24-ethylcholesta-5,22
dienol were elucidated by 220 MHz nuclear magnetic resonance spectrometry. 相似文献
6.
Sun-Chan Jeong Ichiro Katayama Hirokane Kawakami Yutaka Watanabe Hironobu Ishiyama Nobuaki Imai Yoshikazu Hirayama Hiroari Miyatake Masao Sataka Satoru Okayasu Hiroyuki Sugai Shin-Ichi Ichikawa Katsuhisa Nishio Shinichi Mitsuoka Takamitsu Nakanoya Masahito Yahagi Takanori Hashimoto Kazunori Takada Mamoru Watanabe Tomoko Ishikawa Akihiro Iwase 《Journal of Phase Equilibria and Diffusion》2005,26(5):472-476
For the effective use of short-lived radioactive beams, soon to be available at the Tokai Radioactive Ion Accelerator Complex, the authors have developed a radiotracer method for diffusion studies in solids. The experimental test was performed by the measurement of the diffusion coefficients of Li in a sample of the compound βLiAl using an α-emitting radiotracer of 8Li (T1/2=0.84 s). It was found that the time-dependent yields of the α particles from the diffusing 8Li that was initially implanted in the sample could be used as a measure of the diffusivity of the tracer in a nondestructive way. The method was applied to measure the self-diffusion coefficients of Li in βLiGa, and for investigating how the Li diffusion in the Li ionic conductors is affected by the concentration of atomic defects (i.e., the existence of the atomic vacancies of Li and the defects in Ga sites that are replaced by Li). 相似文献
7.
8.
Real-time traffic will be a predominant traffic type in the next generation networks, and networks with 100% reliability and
availability will be required by real-time premium traffic. It is believed that QoS guarantees could be better provided by
connection oriented networks such as Multi Protocol Label Switching (MPLS). These connection oriented networks are more vulnerable
to network failure. Conventional path protection methods perform re-routing to cope with this. However, re-routing always
causes packet losses and results in service outage. These losses are bursty in nature and highly degrade the QoS of the real-time
premium traffic. Thus, 100% availability cannot be achieved by conventional methods. The novel path protection proposed in
this paper recovers the bursty packet losses due to re-routing by using forward error correction (FEC) path. Therefore, it
can provide network architecture with no service outage for such traffic. The numerical results show that the proposed method
can achieve a very high availability for real-time premium traffic in future IP/MPLS networks.
Mitsuo Hayasaka received B.E. and M.E. degrees from the University of Electro-Communications, Tokyo, Japan in 2000 and 2002, respectively. He is currently a Ph.D. student at the University of Electro-Communications, Tokyo, Japan. His research interests involve QoS controls of real-time multimedia communications, and reliable network architecture. He is a member of IEEE, IEICE and IPSJ. Tetsuya Miki received the B.E. degree from the University of Electro-Communications, Tokyo, Japan in 1965, the M.E. and Ph.D. degrees from Tohoku University, Sendai, Japan in 1967 and 1970, respectively. He joined the Electrical Communication Laboratories of NTT in 1970, where he engaged in the research and development of high-speed digital transmission systems using coaxial cable, fiber-optical transmission systems including the initial WDM technologies, fiber-to-the-home systems, ATM systems, network management systems, and broadband network architecture. He is currently a Professor at the University of Electro-Communications, Tokyo, Japan, and is interested in photonic networks, community networks, access networks, and dependable networks. A fellow of the IEEE and IEICE, he also served as vice-president of the IEEE Communications Society in 1998 and 1999 and as vice-president of IEICE in 2003 and 2004. 相似文献
Mitsuo HayasakaEmail: |
Mitsuo Hayasaka received B.E. and M.E. degrees from the University of Electro-Communications, Tokyo, Japan in 2000 and 2002, respectively. He is currently a Ph.D. student at the University of Electro-Communications, Tokyo, Japan. His research interests involve QoS controls of real-time multimedia communications, and reliable network architecture. He is a member of IEEE, IEICE and IPSJ. Tetsuya Miki received the B.E. degree from the University of Electro-Communications, Tokyo, Japan in 1965, the M.E. and Ph.D. degrees from Tohoku University, Sendai, Japan in 1967 and 1970, respectively. He joined the Electrical Communication Laboratories of NTT in 1970, where he engaged in the research and development of high-speed digital transmission systems using coaxial cable, fiber-optical transmission systems including the initial WDM technologies, fiber-to-the-home systems, ATM systems, network management systems, and broadband network architecture. He is currently a Professor at the University of Electro-Communications, Tokyo, Japan, and is interested in photonic networks, community networks, access networks, and dependable networks. A fellow of the IEEE and IEICE, he also served as vice-president of the IEEE Communications Society in 1998 and 1999 and as vice-president of IEICE in 2003 and 2004. 相似文献
9.
A multi-spectral non-local (MSN) method is developed for advanced retrieval of boundary layer cloud properties from remote sensing data, as an alternative to the independent pixel approximation (IPA) method. The non-local method uses data at both the target pixel and neighboring pixels to retrieve cloud properties such as pixel-averaged cloud optical thickness and effective droplet radius. Radiance data to be observed from space were simulated by a three-dimensional (3D) radiation model and a stochastic boundary layer cloud model with two-dimensional (horizontal and vertical) variability in cloud liquid water and effective radius. An adiabatic assumption is used for each cloud column to model the geometrical thickness and vertical profiles of cloud liquid water content and effective droplet radius, neglecting drizzle and cloud brokenness for simplicity. The dependence of radiative smoothing and roughening on horizontal scale, optical thickness and single scattering albedo are investigated. Then, retrieval methods using 250-m horizontal resolution data onboard new generation satellites are discussed. The regression model for the MSN method was trained based on datasets from numerical simulations. The training was performed with respect to various domain averages of optical thickness and effective radius, because smoothing and roughening effects are strongly dependent on the two variables. Retrieval accuracy is discussed here with datasets independent of those used in the training, towards assessing the generality of the technique. It is demonstrated that retrieval accuracy of cloud optical thickness, which is often retrieved from single-spectral visible-wavelength data, is improved the most using neighboring pixel data and secondly using multi-spectral data, and ideally with both. When the IPA retrieval method is applied to optical thickness and effective radius, the root-mean-square relative errors can be 15-90%, depending on solar and view directions. In contrast, the MSN method has errors of 4-10%, which is smaller than IPA by a factor of 2-10. It is also suggested that the accuracy of the MSN method is insensitive to some assumptions in the inhomogeneous cloud input data used to train the regression model. 相似文献
10.
Hideyuki Inui Toshimasa Itoh Keiko Yamamoto Shin-Ichi Ikushiro Toshiyuki Sakaki 《International journal of molecular sciences》2014,15(8):14044-14057
Polychlorinated dibenzo-p-dioxins (PCDDs) and coplanar polychlorinated biphenyls (PCBs) contribute to dioxin toxicity in humans and wildlife after bioaccumulation through the food chain from the environment. The authors examined human and rat cytochrome P450 (CYP)-dependent metabolism of PCDDs and PCBs. A number of human CYP isoforms belonging to the CYP1 and CYP2 families showed remarkable activities toward low-chlorinated PCDDs. In particular, human CYP1A1, CYP1A2, and CYP1B1 showed high activities toward monoCDDs, diCDDs, and triCDDs but no detectable activity toward 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-tetraCDD). Large amino acids located at putative substrate-recognition sites and the F-G loop in rat CYP1A1 contributed to the successful metabolism of 2,3,7,8-tetraCDD. Rat, but not human, CYP1A1 metabolized 3,3'',4,4'',5-pentachlorobiphenyl (CB126) to two hydroxylated metabolites. These metabolites are probably less toxic than is CB126, due to their higher solubility. Homology models of human and rat CYP1A1s and CB126 docking studies indicated that two amino acid differences in the CB126-binding cavity were important for CB126 metabolism. In this review, the importance of CYPs in the metabolism of dioxins and PCBs in mammals and the species-based differences between humans and rats are described. In addition, the authors reveal the molecular mechanism behind the binding modes of dioxins and PCBs in the heme pocket of CYPs. 相似文献