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81.
Jani Keyriläinen Manuel Fernández Alberto Bravin Marja‐Liisa Karjalainen‐Lindsberg Marjut Leidenius Karl von Smitten Mikko Tenhunen Aki Kangasmäki Petri Sipilä Christian Nemoz Pekka Virkkunen Pekka Suortti 《Journal of synchrotron radiation》2011,18(5):689-696
High‐resolution analyser‐based X‐ray imaging computed tomography (HR ABI‐CT) findings on in vitro human breast cancer are compared with histopathology, mammography, computed tomography (CT) and magnetic resonance imaging. The HR ABI‐CT images provided significantly better low‐contrast visibility compared with the standard radiological images. Fine cancer structures indistinguishable and superimposed in mammograms were seen, and could be matched with the histopathological results. The mean glandular dose was less than 1 mGy in mammography and 12–13 mGy in CT and ABI‐CT. The excellent visibility of in vitro breast cancer suggests that HR ABI‐CT may have a valuable role in the future as an adjunct or even alternative to current breast diagnostics, when radiation dose is further decreased, and compact synchrotron radiation sources become available. 相似文献
82.
Yoshihiko Noguchi Tomoyasu Hirose Yujiro Furuya Aki Ishiyama Kazuhiko Otoguro Satoshi Ōmura Toshiaki Sunazuka 《Tetrahedron letters》2012,53(14):1802-1807
We report the first total synthesis and reassignment of the relative stereochemistry of naturally occurring 16-hydroxy-16,22-dihydroapparicine. Our novel route proceeds by a cascade reaction to efficiently construct a 1-azabicyclo[4.2.2]decane core, along with two stereocenters (C-15 and C-16). The C-16 quaternary carbon was constructed through stereospecific 1,2-addition using an indole nucleophile to an aldehyde or a methylketone. The stereospecific synthesis of two diastereomers of the target product has revealed the true relative stereochemistry of the natural compound. 相似文献
83.
Aki Hayashi Hirokazu Nakayama Taro Eguchi Nobuo Nakamura Mitsutomo Tsuhako 《Molecular Crystals and Liquid Crystals》2013,570(2):573-578
Abstract Two kinds of diethylenetriamine (2E3A) intercalation compounds of α-zirconium phosphate with different interlayer distances could be obtained by regulating the reaction time and temperature. Phase I (d = 10.2 Å) slowly transforms to Phase II(d = 15. 8 Å) with transformation enthalpy of 30 kJ-mol?1 in 2E3A aqueous solution. The conformation of 2E3A in Phase I and Phase II were confirmed to be bent and all trans (straight) forms by31P MAS NMR and XRD measurements. Two phases have different adsorption behavior for gaseous carboxylic acids. Phase II can adsorb considerable amount of carboxylic acids whereas Phase I adsorb a little. 相似文献
84.
Abstract Fibrous titania was synthesized by the solvothermal reactions of H1Ti4O9 nH2in different media. H2Ti4O9·nH2O transformed in steps to H2Ti8O17, monoclinic TiOz, anatase and rutile. The phase transformation temperature and microstructure of the products changed significantly depending on the heating environment. The critical temperature at which anatase appeared in liquid media was much lower than that in air. The titania fibers consisted of nanocrystals of TiO2. The crystallite size and crystallinity of titania decreased with decreasing the dielectric constant of the reaction medium. Consequently, the photocatalytic activity of titania changed with heat treatment media in the following sequence: ethanol, methanol > water > air, i.e., fibrous titania possessing excellent photocatalytic activity could be obtained by the solvothermal reactions using alcohol such as methanol and ethanol. Titania powders crystallized by the solvothermal reaction in methanol also possessed excellent thermal stability. 相似文献
85.
Some new exact distributions on coupon collector’s waiting time problems are given based on a generalized Pólya urn sampling. In particular, usual Pólya urn sampling generates an exchangeable random sequence. In this case, an alternative derivation of the distribution is also obtained from de Finetti’s theorem. In coupon collector’s waiting time problems with $m$ kinds of coupons, the observed order of $m$ kinds of coupons corresponds to a permutation of $m$ letters uniquely. Using the property of coupon collector’s problems, a statistical model on the permutation group of $m$ letters is proposed for analyzing ranked data. In the model, as the parameters mean the proportion of the $m$ kinds of coupons, the observed ranking can be intuitively understood. Some examples of statistical inference are also given. 相似文献
86.
Nobumitsu Sakai Masato Takakura Harutoshi Imamura Miki Sugimoto Yasuto Matsui Hirokazu Miyoshi Aki Nakayama Minoru Yoneda 《Journal of nanoparticle research》2012,14(5):849
We analyzed the whole-body distribution of 14C–ADP-labeled silica nanoparticles (14C–ADP–SiO2 nanoparticles) and submicron particles (14C–ADP–SiO2 submicron particles) after intravenous injection into ICR mice. The 14C–ADP–SiO2 nanoparticles and submicron particles were synthesized before the injection and the particle size was 19.6 and 130 nm, respectively.
Similarly, the shape was spherical and the crystallinity was amorphous. After the synthesis, we injected mice with the 14C–ADP–SiO2 nanoparticles or the 14C–ADP–SiO2 submicron particles and dissected tissues after 1, 2, 4, 8 and 24 h. The radioactivity in the tissues was measured with a
liquid scintillation counter. As a result, the retention percentage in bone, skin, lymph nodes, and the digestive mixture
was at least twofold higher in the 14C–ADP–SiO2 nanoparticles-exposed mice, whereas the retention percentage in the kidney was statistically higher in the 14C–ADP–SiO2 submicron particles-exposed mice. Both types of 14C–ADP–SiO2 particles mainly translocated to the muscle, bone, skin, and liver, but hardly translocated to the brain and olfactory bulb.
Furthermore, the 14C–ADP–SiO2 nanoparticles had a higher retention percentage (62.4 %) in the entire body at 24-h post-injection than did the 14C–ADP–SiO2 submicron particles (50.7 %). Therefore, we suggested that the 14C–ADP–SiO2 nanoparticles might be more likely than the 14C–ADP–SiO2 submicron particles to be retained in the body, and consequently they might be gradually accumulated by chronic exposure. 相似文献
87.
Novel highly substituted hydroxy thiophene motifs were designed and synthesized as viable amido phenol and sulfonamido phenol bioisosteres. Hydroxy group-directed regioselective bromination and palladium-catalyzed amination of thienyl bromide via Buckwald protocol are the key elements of the synthetic approach. The hydroxy thiophene-containing compounds displayed good binding inhibitions. 相似文献
88.
Intrauterine devices (IUDs) have been viewed as an effective form of contraception. However, the mechanism by which IUDs disturb fertility remains controversial. This study aimed to evaluate the effects of IUDs on uterine contractility using cine MR. Eleven healthy female volunteers of reproductive age bearing IUDs and 12 women not bearing IUDs were evaluated during the periovulatory phase. MR images were obtained with a 1.5-T magnet, acquiring 60 serial images every 3 s via half-Fourier acquisition single-shot turbo spin echo to be displayed on cine mode. Assessments were based on (a) the presence of peristaltic waves, (b) the frequency and direction of peristaltic waves and (c) the extent of peristaltic waves. Static images were evaluated for thickness of the junctional zone (JZ) and myometrium. A fundo-cervical (FC)-directed peristaltic wave was identified in 4 of 11 IUD-bearing subjects and in only 1 of 12 subjects from the control group. FC waves extended through more than half of the thickness of the myometrium. Peristaltic frequency in IUD users (5.0/3 min) was less than that of the control group (6.5/3 min). The JZ and myometrium were significantly thicker in IUD users. FC-directed waves were more often observed in IUD-bearing subjects, which might explain the inhibition of active sperm transport. 相似文献
89.
Sigeo Aki 《Annals of the Institute of Statistical Mathematics》1999,51(1):1-15
In this paper we study exact distributions of runs on directed trees. On the assumption that the collection of random variables indexed by the vertices of a directed tree has a directed Markov distribution, the exact distribution theory of runs is extended from based on random sequences to based on directed trees. The distribution of the number of success runs of a specified length on a directed tree along the direction is derived. A consecutive-k-out-of-n:F system on a directed tree is introduced and investigated. By assuming that the lifetimes of the components are independent and identically distributed, we give the exact distribution of the lifetime of the consecutive system. The results are not only theoretical but also suitable for computation. 相似文献
90.
Sooner and Later Waiting Time Problems for Runs in Markov Dependent Bivariate Trials 总被引:2,自引:2,他引:0
In this paper we study exact distributions of sooner and later waiting times for runs in Markov dependent bivariate trials. We give systems of linear equations with respect to conditional probability generating functions of the waiting times. By considering bivariate trials, we can treat very general and practical waiting time problems for runs of two events which are not necessarily mutually exclusive. Numerical examples are also given in order to illustrate the feasibility of our results. 相似文献