ZnO nanopillar arrays with high aspect ratios, such as the one shown in the figure, are fabricated from aqueous solutions at low temperatures using a polymer mold. The shape and dimensions of the ...nanopillars can be tuned by appropriately patterning the polymer mold. A hexagonal ZnO nanopillar array shows photonic bandgaps at visible wavelengths, as predicted by photonic band structure calculations.
A wet-chemical deposition method of synthesizing highly oriented, transparent ZnO films on a crystalline template is described. Multi-nucleation and the subsequent growth of ZnO nanodomains at an ...early stage of wet-chemical deposition leads to the formation of thin hexagonal platelike ZnO crystals spread over the template film. A subsequent temperature increase allows the growth of oriented rods, whose size depends on that of the platelike crystals. Consequently, oriented ZnO films with various microstructures can be synthesized by controlling the size of the ZnO plates at an early stage of deposition.
Total Synthesis of (−)-Coriolin Mizuno, Hajime; Domon, Kei; Masuya, Keiichi ...
Journal of organic chemistry,
04/1999, Letnik:
64, Številka:
8
Journal Article
Recenzirano
An efficient synthetic method for (−)-coriolin has been developed on the basis of a 3+2 cycloaddition reaction of a 1-(methylthio)-2-siloxyallyl cationic species and vinylsulfides. An ...enantiomerically pure C-ring unit was prepared through optical resolution of five-membered allyl ester 6b using a lipase. The first 3+2 cycloaddition reaction of C-ring unit ( S )-7 gave bicyclic ketones 8 and 9, which were easily converted into vinyl sulfide 11. Stereoselective construction of the A-ring was achieved by the second 3+2 cycloaddition reaction of the BC-ring unit. New methods for introduction of the oxygen functional groups to the triquinane skeleton were also developed for the last stages of the total synthesis. Thus, the C7 hydroxyl group was introduced by epoxidation of dienol silyl ether 17, and stereocontrolled construction of the spiro epoxide moiety was accomplished on the basis of a Darzens-type reaction.
A new synthetic method for functionalized cyclopentanones was developed on the basis of a 3+2 cycloaddition reaction of a 1-(methylthio)-2-siloxyallyl cationic species and olefins. Allyl acetates 1a ...and 1b, which are the precursors of the allyl cationic species, are easily prepared in three or four steps from commercially available compounds. Under the influence of EtAlCl2 or AlCl3, 1a or 1b reacted with various kinds of olefins such as enol ethers, vinyl sulfides, styrenes, and trialkylolefins to afford the corresponding cyclopentanones in good yields. It is noteworthy that the sterically more hindered regioisomer was predominantly formed in every case. Furthermore, the reactions of 1b with vinyl sulfides exhibited surprisingly high stereoselectivity, which can be rationalized by the six-membered transition state models involving an orbital interaction between the sulfur atom of the vinyl sulfide and the α-carbon of the allyl cation.
Formal total synthesis of coriolin has been accomplished on the basis of a 3+2 cycloaddition reaction of a vinylsulfide with 3-(methylthio)-2-siloxyallyl cation. A five-membered vinylsulfine as a C ...ring unit was prepared in five steps from commercially available compounds. The first 3+2 cycloaddition reaction gave the BC ring intermediate, which was then converted into a bicyclic vinylsulfide in three steps. The construction of the A ring by the second 3+2 cycloaddition reaction followed by two-step-conversion afforded the tricyclic enone (30% overall yield from isobutyronitrile) which has previously been synthesized and converted into coriolin.
Graphic
Background
: The clinical effect of phototherapy for neonatal hyperbilirubinemia is based on the production and elimination of cyclobilirubin. Generally, the clinical effect of light sources is ...estimated by the reduction in the total serum bilirubin level. One procedure with less invasiveness than blood collecting is urine collection. Whether the effectiveness of light sources used for phototherapy could be assessed using measurements of bilirubin photoisomers in urine was studied.
Methods
: This study was a retrospective analysis of 38 term infants with hyperbilirubinemia who underwent phototherapy. Bilirubin fractions in serum and urine before and 24 h after the phototherapy were measured by high‐performance liquid chromatography. The light sources used for the phototherapy were blue‐white light (n = 11), Biliblanket plus high output (n = 13) or green light (n = 14). The relationships between serum and urine bilirubin photoisomers after phototherapy and whether the levels of urine bilirubin photoisomer are affected by the light sources with different wavelength characteristic were analyzed.
Results
: There was no correlation between serum (ZE)‐bilirubin and urine configurational isomers, but a weak positive correlation between serum (EZ)‐cyclobilirubin and urine structural isomers after phototherapy. Although serum (ZE)‐bilirubin levels depended on the wavelength characteristic of each light source during phototherapy, the urine configurational isomer levels did not depend on it. The increase in serum (EZ)‐cyclobilirubin levels and the urine structural isomer levels were mostly in agreement.
Conclusions
: The urine bilirubin structural isomers may be used to estimate the serum (EZ)‐cyclobilirubin levels and to evaluate the clinical effects of light sources.
A high-fidelity attitude estimation technique for wide and irregular movements is proposed, in which heterogeneous inertial sensors are combined in complementary way. Although the working frequency ...ranges of each sensor are not necessarily complementary, inverse sensor models are utilized in order to restore the original movements. In the case of 3D rotation, the sensor dynamics displays a highly nonlinear property. Even if it is approximated by a linear system, the inverse model of a sensor tends to be non-proper and unstable. An idea is to decouple it into the dynamics compensation part approximated by a linear transfer function and the strictly nonlinear coordinate transformation part. Bandpass filters inserted before the coordinate transformation guarantee that the total transfer function becomes proper and stable. Particularly, the differential operator of a high-pass filter cancels the integral operator included in the dynamics compensation of the rate gyroscope, which causes instability. The proposed method is more beneficial than Kalman filter in terms of the implementation since it facilitates a systematic design of the filter.
