On the basis of structural information for the cyclic hexapeptide endothelin (ET) receptor antagonist, TAK-044, a series of thieno[2,3-d]pyrimidine-2,4-dione derivatives bearing a carboxyl group and aromatic rings that were important for receptor binding were designed, synthesized, and evaluated for ET receptor binding affinities and inhibitory activities against ET-induced vasoconstriction. Optimization of each substituent in the thieno[2,3-d]pyrimidine ring led to the discovery of a novel and potent nonpeptide ET receptor antagonist, 6-(4-methoxymethoxyphenyl)-5-methylsulfonylaminomethyl-1-(2- methylthiobenzyl)-2,4-dioxo-1,2,3,4-tetrahydrothieno[2,3-d]p yrimidine-3- acetic acid (32 g), which binded to human ETA and ETB receptor subtypes with affinities (IC50) of 7.6 and 100 nM, respectively. Compound 32 g effectively antagonized ET-induced vasoconstriction and the inhibitory effect mediated by the ETB receptor was more potent than that of bosentan, while the inhibitory effect mediated by the ETA receptor was slightly less potent than that of bosentan. 相似文献
Oxide semiconductors have been examined to develop NOx sensors for exhaust monitoring. Titania doped with trivalent elements, such as Al3+, Sc3+, Ga3+ or In3+, has a good sensitivity and selectivity to NO between 450 and 550 °C, and shows rapid response. A sensor probe for monitoring exhaust NOx has been fabricated. Many kinds of interference gases, such as C3H6, CO and SO2, have been found to have only a slight influence on the sensor response to NO. The influence of O2 and H2O is also negligible, except for the cases of 0% H2O and fuel-rich conditions. In accordance with these results, the sensor probe operates satisfactority in the exhaust gas of various combustion conditions without interference from the various kinds of gas species in the exhaust gases. 相似文献
The impact of micro-alloying on tensile behavior at strain rates in various ranges is examined using five types of extruded Mg-0.3 at. pct Mn–0.1 at. pct X ternary alloys, where X is selected as a common element, Al, Li, Sn, Y or Zn. Microstructural observations reveal that the average grain size of these extruded alloys is between 1 and 3 μm, and these micro-alloying elements segregate at grain boundaries. In room temperature tensile and compression tests, these results show that the mechanical properties and deformation behavior are influenced by the micro-alloying element, even as a small addition of 0.1 at. pct. Mg–Mn–Y and Mg–Mn-Zn alloys show higher strength and smaller strain rate sensitivity (m-value) among the present alloys, owing to the rate-controlling mechanism as dislocation slip. On the other hand, the Mg–Mn–Li alloy exhibits the largest elongation to failure in tension and the highest strain rate sensitivity, associated with high contribution of grain boundary sliding to deformation. These differences are due to the grain boundary segregation of the micro-alloying elements. Compared to the common Mg alloys, the present ternary alloys also show a trade-off relationship between strength and ductility, which is similar to that of the well-known Mg alloys; however, these properties of the Mg–Mn system ternary alloys could be controlled via the type of micro-alloying elements with a chemical content of 0.1 at. pct.
Summary Polysilanes with an optically active alkoxy group, i.e., (S)-(+)-2-butoxy, (R)-(-)-2-butoxy, (S)-(-)-2-methyl-1-butoxy, and (S)-(+)-3,7-dimethyl-1-octoxy, at the terminal positions, the chiral carbon centers of which were located at the α, β, and γ
positions relative to the oxygen, respectively, were prepared, and the effect of the position of chiral center of the terminal
optically active group on the induction of optical activity in polysilanes was investigated. The circular dichroism (CD) spectra
of these polymers showed positive Cotton signals around 340 nm at temperatures below -20 °C, but the intensities were small,
indicating that the optically active groups at the terminal positions have some ability, albeit small, to induce optical activity
to the polysilanes. Further, the optically active (S)-(+)-2-butoxy and (R)-(-)-2-butoxy groups did not control the helical sense direction of the polymers, despite the different chiral stimuli from
the 2-butoxy groups introduced to the terminal positions. To control the helical structure of polysilanes by the use of optically
active terminal groups, appropriate optically active groups are required. 相似文献
Novel Lu-α-SiAlON ceramics were produced by hot pressing mixtures of Si3N4, Lu2O3, AlN, and Al2O3 at 1950°C for 2 h in a nitrogen atmosphere. The resultant SiAlON was fully dense and possessed a uniform, equiaxed microstructure with a grain size of ∼1 μm, which resulted in a high hardness of >19 GPa. In addition to high hardness, the sample showed very high optical transparency in the visible light region, with >70% transmission at higher wavelengths. This high transparency was attributed to the uniform, dense microstructure and lack of residual grain-boundary phase. 相似文献
The fracture energies of the tape-cast silicon nitride with and without 3 wt% rod-like β-Si3N4 seed addition were investigated by a chevron-notched-beam technique. The material was doped with Lu2O3–SiO2 as sintering additives for giving rigid grain boundaries and good heat resistance. The seeded and tape-cast silicon nitride has anisotropic microstructure, where the fibrous grains grown from seeds were preferentially aligned parallel to the casting direction. When a stress was applied parallel to the fibrous grain alignment direction, the strength measured at 1500°C was 738 MPa, which was almost the same as room temperature strength 739 MPa. The fracture energy of the tape-cast Si3N4 without seed addition was 109 and 454 J/m2 at room temperature and 1500°C, respectively. On the contrary, the fracture energy of the seeded and tape-cast Si3N4 was 301 and 781 J/m2 at room temperature and 1500°C, respectively, when a stress was applied parallel to the fibrous gain alignment. The large fracture energies were attributable primarily to the unidirectional alignment fibrous Si3N4 grains. 相似文献
A W2C-nanoparticle-reinforced Si3N4-matrix composite was fabricated by sintering porous Si3N4 that had been infiltrated with a tungsten solution. During the sintering procedure, nanometer-sized W2C particles grew in situ from the reaction between the tungsten and carbon sources considered to originate mainly from residual binder. The W2C particles resided in the grain-boundary junctions of the Si3N4, had an average diameter of ∼60 nm, and were polyhedral in shape. Because the residual carbon, which normally would obstruct sintering, reacted with the tungsten to form W2C particles in the composite, the sinterability of the Si3N4 was improved, and a W2C–Si3N4 composite with almost full density was obtained. The flexural strength of the W2C–Si3N4 composite was 1212 MPa, ∼34% higher than that of standard sintered Si3N4. 相似文献
The balanced corpus of contemporary written Japanese (BCCWJ) is Japan’s first 100 million words balanced corpus. It consists of three subcorpora (publication subcorpus, library subcorpus, and special-purpose subcorpus) and covers a wide range of text registers including books in general, magazines, newspapers, governmental white papers, best-selling books, an internet bulletin-board, a blog, school textbooks, minutes of the national diet, publicity newsletters of local governments, laws, and poetry verses. A random sampling technique is utilized whenever possible in order to maximize the representativeness of the corpus. The corpus is annotated in terms of dual POS analysis, document structure, and bibliographical information. The BCCWJ is currently accessible in three different ways including Chunagon a web-based interface to the dual POS analysis data. Lastly, results of some pilot evaluation of the corpus with respect to the textual diversity are reported. The analyses include POS distribution, word-class distribution, entropy of orthography, sentence length, and variation of the adjective predicate. High textual diversity is observed in all these analyses. 相似文献