An efficient synthesis of a highly potent and selective IP (PGI(2) receptor) agonist that is not structurally analogous to PGI(2) is described. This synthesis is accomplished through the following key steps: Nucleophilic ring-opening of 3-(4-chlorophenyl)-oxazolidin-2-one prepared by a one-pot procedure with 4-piperidinol and selective O-alkylation of 1-(2-(4-chlorophenylamino)ethyl)piperidin-4-ol. The obtained compound is a potent and selective IP agonist displaying a long duration of action. 相似文献
The effects of the low-energy electron beam on ZnO single crystals were investigated by cathodoluminescence (CL), Time-of-Flight Electron Stimulated Desorption (TOF-ESD) and Temperature Programmed Desorption (TPD). Under e-beam irradiation, the ultraviolet (UV) emission decreases exponentially for O-face, while it increases and then decreases for Zn-face. Meanwhile, a large desorption of H+ is observed by TOF-ESD for both O- and Zn-faces. On the other hand, an increase of H in the irradiated volume is observed after stopping the e-beam irradiation. Similar H2 desorption is found by TPD for both faces. These data suggest that the decrease of the UV intensity is related to H desorption. 相似文献
An antireflective structure with two-dimensional 300-nm periodicity was fabricated on a phosphate glass surface using an imprinting process with a SiC mold. The optimized structure designed using RCWA calculation was a convex circular cone sharing the ridge line of adjacent cones. The SiC mold was fabricated using electron beam drawing and subsequent reactive ion etching with CHF3 and O2 gases. The glass’ surface reflectance was estimated as 0.2% at 530 nm wavelength, which was approximately 1/20 that of the optically polished surface. 相似文献
The bicyclic depsipeptide histone deacetylase (HDAC) inhibitors spiruchostatins A and B, 5′′‐epi‐spiruchostatin B and FK228 were efficiently synthesized in a convergent and unified manner. The synthetic method involved the following crucial steps: i) a Julia–Kocienski olefination of a 1,3‐propanediol‐derived sulfone and a L ‐ or D ‐malic acid‐derived aldehyde to access the most synthetically challenging unit, (3S or 3R,4E)‐3‐hydroxy‐7‐mercaptohept‐4‐enoic acid, present in a D ‐alanine‐ or D ‐valine‐containing segment; ii) a condensation of a D ‐valine‐D ‐cysteine‐ or D ‐allo‐isoleucine‐D ‐cysteine‐containing segment with a D ‐alanine‐ or D ‐valine‐containing segment to directly assemble the corresponding seco‐acids; and iii) a macrocyclization of a seco‐acid using the Shiina method or the Mitsunobu method to construct the requisite 15‐ or 16‐membered macrolactone. The present synthesis has established the C5′′ stereochemistry of spiruchostatin B. In addition, HDAC inhibitory assay and the cell‐growth inhibition analysis of the synthesized depsipeptides determined the order of their potency and revealed some novel aspects of structure–activity relationships. It was also found that unnatural 5′′‐epi‐spiruchostatin B shows extremely high selectivity (ca. 1600‐fold) for class I HDAC1 (IC50=2.4 nM ) over class II HDAC6 (IC50=3900 nM ) with potent cell‐growth‐inhibitory activity at nanomolar levels of IC50 values. 相似文献
This paper represents the hydrothermal synthesis of new isomorphous lanthanide–vanadium complexes with one-dimensional coordination polymers: [Pr2(VO2)2(dipic)4(H2O)9] · nH2O with dipic = pyridine-2,6-dicarboxylic acid and n = 7.75. The structure determination shows a unique one-dimensional structure in which three types of chains run along the c-axis: the chain of positively charged praseodymium complexes bridged by a dipic ligand ([Pr(dipic)(H2O)5]+), the chain of negatively charged, stacked vanadium complexes ([VO2(dipic)]−), and the chain of neutral praseodymium complexes with a bridged dipic ligand and a coordinating dipic ligand ([Pr(dipic)[VO2(dipic)](H2O)4]). Such one-dimensional chains provide open channels which can accommodate water molecules. Not only accommodated water molecules but also ones coordinated to praseodymium ions were easily removed and absorbed upon heating at 200 °C and exposure of humidity at room temperature, respectively. 相似文献
After decades of efforts by many researchers, we have succeeded in realizing a near‐ideal polymer network. This network, the Tetra network, is made by cross‐end‐coupling of tetra‐arm polymer modules. The mechanical energy dissipation was extremely low (tan δ ≈ 10−4). The macroscopic stress–strain relationship of the Tetra network was in good agreement with that of microscopic elastic blobs. The maximum breaking strength was extremely high (≥27 MPa). These results indicate that the Tetra network is closer to an ideal polymer network than any other conventional model networks. Because the Tetra network can be treated as uniformly packed elastic blobs, it should help apply the knowledge of single polymer chains seamlessly to the design of polymer materials and help further develop the theory of rubber elasticity.
We propose an optical implementation of a parallel two-step phase-shifting digital holography that utilizes a polarization
technique. The implementation uses a phase-shifting array device consisting of a retarder array attached to an image sensor,
and does not require the optical system to image the phase-shifting array device onto the image sensor required for the previously
reported optical implementation of the parallel two-step phase-shifting digital holography. Then, the proposed implementation
is essentially simple to align and compose. A preliminary experiment showed that the parallel two-step phase-shifting digital
holography based on the proposed implementation can remove the conjugate image clinging to the image reconstructed by Fresnel
transform alone with DC term suppression. Also, when the reconstruction distance was changed, the qualities of the reconstructed
images were quantitatively evaluated by using normalized root-mean-square error. It was clarified that the proposed implementation
was superior to other parallel phase-shifting digital holographies and Fresnel transform alone. Thus, the validity of the
proposed implementation was confirmed. 相似文献
A new three‐dimensional graphics program, SaxsMDView, is described. The program performs a three‐dimensional graphical representation for protein molecules along with the force vector (or vector potential) applying to each atom. The displayed object can be rotated and translated in arbitrary directions by interactive mouse manipulation. While SaxsMDView was originally intended to visualize the result of SAXS_MD, a previously developed program based on the restrained molecular dynamics with small‐angle X‐ray scattering constraints, it can also be useful for graphical representation of other objects such as coarse‐grained molecular models reconstructed by ab initio modelling or solvent site‐dipole field vectors induced around the protein molecule. Some examples of the application of the program including the graphical analyses of the results with SAXS_MD are also presented. 相似文献
The oscillatory profile of diffuse scattering of ordered crystal PbF2 is observed by time-of-flight (TOF) neutron scattering measurement. The theoretical expression of diffuse scattering intensity including the correlation effects among the thermal displacements of atoms is used to analyze the diffuse scattering profile of PbF2. The theoretical expression is effective for the analysis of the diffuse scattering data by the TOF measurement. 相似文献
Initial oxidation of iron and manganese mono-silicides (FeSi and MnSi) surfaces was studied by X-ray photoelectron spectroscopy (XPS). Clean surfaces of these silicides were prepared by fracturing in an ultra high vacuum, and then the fractured surfaces were oxidized by exposing to high-purity oxygen at pressures up to 1.3 Pa. For the clean FeSi surface, positive chemical shifts of the Fe 2p3/2 and Si 2p peaks from elemental Fe and Si were 0.5 eV and 0.1 eV, respectively. For the clean MnSi surface, a negative chemical shift of the Si 2p peak from elemental Si was 0.1 eV. Iron on the FeSi surface was oxidized at an oxygen pressure of 1.3 Pa, whereas the silicon was oxidized under the pressure of 1.3 × 10−6 Pa, indicating that oxidation of silicon occurred prior to that of iron. Manganese and silicon on the MnSi were simultaneously oxidized in the range from 1.3 × 10−6 Pa to 1.3 × 10−3 Pa; however, over the pressure of 1.3 Pa, the oxidation of manganese occurs prior to that of silicon. These oxidation behaviors at low oxygen pressures were similar to those of the FeSi and MnSi fractured in air. 相似文献