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131.
Hifumi H Yamaoka S Tanimoto A Citterio D Suzuki K 《Journal of the American Chemical Society》2006,128(47):15090-15091
A new nanoparticulate inorganic-organic hybrid-type positive contrast agent (CA), PGP/dextran-K01, was synthesized based on a GdPO4 inorganic core as a relaxation-time-shortening moiety and a dextran-coating, which generates monodispersibility in water, a high relaxation-time-shortening effect by retaining a large number of water molecules in proximity of the core and toxicity reduction in in-vivo studies. This PGP/dextran-K01 nanoparticle has high r1 and r2 values and a significantly low r2/r1 value, 1.1, which is unprecedented and which is the lowest value among existing nanoparticulate CAs indicating that PGP/dextran-K01 is a positive contrast agent. Because of this low r2/r1 value and the nanoparticulate shape, PGP/dextran-K01 will be a useful clinical substitute for negative CAs based on iron oxides. 相似文献
132.
Intermolecular carbon radical addition to the carbon-nitrogen double bond of ketimines was studied. In the study on the reactivity of various aldimines, we found that the aldimine 7 having a phenolic hydroxyl group shows an excellent reactivity toward nucleophilic carbon radicals. A remarkable effect of phenolic hydroxyl group is assumed to be the stabilization of intermediate aminyl radical provided by a hydroxyl group. The screening of reactive ketimino acceptors showed that ketimines 15, 17, and 19 having a phenolic hydroxyl group exhibit excellent reactivities. The radical addition to ketimines 15, 17, and 19 took place regioselectively at the imino carbon to give the C-alkylated products without the formation of N-alkylated products. Enantioselective ethyl radical addition to ketimine 15 using chiral box ligand and Zn(OTf)2 gave the diethylated product 30 in 80% ee. 相似文献
133.
Tetsuji Yamaoka Ellyana Njatawidjaja Atsushi Kasai Carlos Alberto Agudelo Tomo Ehashi Sachiro Kakinoki Satoshi Kato Atsushi Mahara 《Polymer Degradation and Stability》2013
Tissue adhesions cause severe and life-threatening conditions, including pain, infertility, and heart defects. The purpose of this study is to develop an anti-adhesion membrane that sticks onto the injured tissues or organs in order to avoid the suturing of the membrane which may lead to the unnecessary tissue adhesion. We previously developed poly(lactic acid)-poly(ethylene glycol) (PLA-PEG) multiblock copolymers as soft, water absorbable, and quickly degradable biomaterials. The copolymer with the highest PEG content adsorbs body fluid in vivo and sticks to the tissues. In the present study thin film and nanofiber mat were prepared from the copolymer and evaluated in vitro and in vivo. The hydrophilicity and the degradation rate increased with the increased PEG content of the multiblock copolymers. The copolymer with PEG content of 88% (LE(m)-88) was quickly swollen, become viscous, and rapidly collapsed in PBS, which was suitable feature for adhesion prevention material without suturing. Various double layered membranes with different characteristics were evaluated in vivo by applying onto the cecum scrubbed with abrasive paper, and onto the heart surface after pericardium removal. LE(m)-88 was swollen with tissue fluid and had a hydrogel-like nature. LE(m)-88 film/LE(m)-32 film double layered membrane was found to be the most effective in preventing tissue adhesion in cecum model. This excellent performance was confirmed in the rat heart adhesion model. In both models, the LE(m)-32 support film was detached from the site of application, which leads to the healing without adhesion. 相似文献
134.
Mutsumi Kimura Masaaki HirakoToshifumi Yamaoka Satoshi Tani 《Solid-state electronics》2011,63(1):137-139
We have developed a simulation algorithm of carrier transport subject to Lorentz force in semiconductor films. The Lorentz current is discretized with the drift and diffusion currents, and the simulation algorithm is implemented in finite difference methods. Hall effect around a grain boundary in a polycrystalline semiconductor film is evaluated as a simulation example, and it is found that a high Hall voltage is generated at the grain boundary. 相似文献
135.
We designed a logic-library-friendly SRAM array. The array uses rectangular-diffusion cell (RD cell) and delta-boosted-array-voltage scheme (DBA scheme). In the RD cell, the cell ratio is 1.0, and it reduces the imbalance of the cell ratio. A low supply voltage deteriorates the static noise margin, however, the DBA scheme compensates it. Using the combination of RD cell and DBA scheme, a 32-kB test chip achieves 0.4-V operation at 4.5-MHz frequency, 140-/spl mu/W power dissipation, and 0.9-/spl mu/A standby current. 相似文献
136.
137.
Shinobu Yamaoka Osamu Fukunaga Terumasa Ono Eiichi Iizuka Seiichi Asami 《Journal of solid state chemistry》1973,6(2):280-285
The phase diagram of Li2WO4 has been determined at high pressure up to 160 kbars and a temperature of 800°C. Three new high-pressure phases have been found in the present study. Crystallographic data are given for Li2WO4 III and Li2WO4 IV by means of single crystal and powder X-ray analyses. Li2WO4 III is orthorhombic with the large unit cell containing 16 molecules and having the edges: a0 = 10.12(4) Å, b0 = 10.07(1) Å, c0 = 11.68(6) Å. Li2WO4 IV has an orthorhombic unit cell with the parameters: a0 = 4.96(7) Å, b0 = 9.72(8) Å, c0 = 5.93(8)Å and Z = 4. The total volume decrease is estimated to be 24.8% through the high pressure transformations in Li2WO4. No spinel-like structure could be found in the present study. 相似文献
138.
Yamaoka K 《Colloids and surfaces. B, Biointerfaces》2007,56(1-2):97-Optics
Anomalous electric birefringence signals of a sonicated and column-fractionated medium-size calf thymus DNA sample (bp = 570) in Na+ solutions were measured at 7 °C. The reversing-pulse electric birefringence (RPEB) signal pattern was theoretically calculated in the low electric field region for two axially symmetric models coexisting in equilibrium in solution. The RPEB theory is based on the electric dipole moment due to ion-fluctuation along the longitudinal direction and the electric polarizability anisotropy (Δ′), together with various electric and optical parameters assigned to the models. An analytical method was developed for the steady-state birefringence of the two-component system in a wide range of electric fields. The NaDNA samples exhibit complex RPEB patterns mixed with negative- and positive-going profiles. An experimental RPEB signal of NaDNA at an absorbance (A260) of 8 was fitted to theoretical curve at weak electric fields. The anomalous RPEB signal was attributed to the component 2, which shows a dip in the buildup and another in the reverse processes with a positive sign and a larger relaxation time. For the component 1, a normal DNA profile with negative sign is associated with a narrow dip in the reverse and a faster relaxation time in the decay signal. The field-strength dependence of observed steady-state birefringence δ(∞) could be fitted for NaDNA at A260 = 8 by the SUSID orientation function with saturated ionic and electronic moments. An apparent positive maximum and the sign reversal in δ(∞) at weak electric fields is an interplay between the positive component 2 with positive optical factor Δg and negative Δ′ and the negative component 1 with negative Δg and positive Δ′. Possible conformation of two DNA components involved in solution was estimated. 相似文献
139.
Summary We establish new comparison theorems on the oscillation of solutions of a class of perturbed half-linear differential equations.
These improve the work of Elbert and Schneider [6] in which connections are found between half-linear differential equations
and linear differential equations. Our comparison theorems are not of Sturm type or Hille--Wintner type which are very famous.
We can apply the main results in combination with Sturm's or Hille--Wintner's comparison theorem to a half-linear differential
equation of the general form (|x'|α-1x')' + a(t) |x|α-1x = 0. 相似文献
140.