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91.
Beam shaping and homogenization techniques are essential to optimize a large number of laser-material processing applications and laser-material interaction studies. In this paper, we present an innovative approach for modeling laser beam homogenization by means of the integration method. The numerical results are compared with experimental data, and the influence of the measurement technique is discussed. The enhancement of the homogenization capability using an asymmetric divider is also presented and discussed. 相似文献
92.
Kana Yamamoto Kaustav BiswasChristoph Gaul Samuel J. Danishefsky 《Tetrahedron letters》2003,44(16):3297-3299
Ring closing metathesis (RCM) has emerged as a powerful tool to construct macrocyclic ring systems. However, the product distribution of monomer and oligomers is often a problem in the formation of medium to large rings. In the course of synthetic studies on the natural product radicicol and its analogs, we have found that the reaction temperature, along with concentration, has significant impact on the outcome of the product ratio. Specifically, carrying out the RCM reaction in refluxing toluene (110°C) at higher dilution affords improved yields of the monomeric macrocycle. Similar observations for another family of macrolactone natural products, the epothilones, are also reported. 相似文献
93.
We study the monodromies at infinity of confluent A-hypergeometric functions introduced by Adolphson [2]. In particular, we extend the result of [38] for non-confluent A-hypergeometric functions to the confluent case. The integral representation by rapid decay homology cycles proved in [9] will play a central role in the proof. 相似文献
94.
Kana Matsudaira Yuki Mimura Junichi Hotei Prof. Dr. Shigeyuki Yagi Dr. Ken-ichi Yamashita Prof. Dr. Michiya Fujiki Prof. Dr. Yoshitane Imai 《化学:亚洲杂志》2021,16(8):926-930
The magnetic circularly polarized luminescence (MCPL) and photoluminescence (PL) spectra of achiral (2,3,7,8,12,13,17,18-octaethylporphyrinato)platinum(II), PtOEP , and [2-(4′,6′-difluorophenyl)pyridinato-N,C2′]platinum(II) acetylacetonate-O,O, F2-ppyPt(acac) , in toluene and dichloromethane solutions were recorded under an external magnetic field of 1.6 T with N-up and S-up Faraday geometries. The MCPL signs of PtOEP and F2-ppyPt(acac) were controlled solely by changing the N-up and S-up geometries. The MCPL/PL wavelengths of F2-ppyPt(acac) in solutions were varied by the ratio of the monomeric and excimeric species. 相似文献
95.
Yuefan Wang Hanjing Peng Zufeng Guo Brett R. Ullman Kana Yamamoto Sam Y. Hong Jun O. Liu 《Chemical science》2021,12(34):11484
Rapadocin is a novel rapamycin-inspired polyketide–tetrapeptide hybrid macrocycle that possesses highly potent and isoform-specific inhibitory activity against the human equilibrative nucleoside transporter 1 (hENT1). Rapadocin contains an epimerizable chiral center in phenylglycine and an olefin group, and can thus exist as a mixture of four stereoisomers. Herein, we report the first total synthesis of the four stereoisomers of rapadocin using two different synthetic strategies and the assignment of their structures. The inhibitory activity of each of the four synthetic isomers on both hENT1 and hENT2 was determined. It was found that the stereochemistry of phenylglycine played a more dominant role than the configuration of the olefin in the activity of rapadocin. These findings will guide the future design and development of rapadocin analogs as new modulators of adenosine signaling.Rapadocin is a novel rapamycin-inspired polyketide–tetrapeptide hybrid macrocycle that possesses highly potent and isoform-specific inhibitory activity against the human equilibrative nucleoside transporter 1 (hENT1). 相似文献
96.
Vidyasagar A Handore K Sureshan KM 《Angewandte Chemie (International ed. in English)》2011,50(35):8021-8024
Sweet and low: Two sugar-based supergelators can congeal oils to produce highly transparent gels with glass-like refractive indices showing low UV transmittance and high visible transmittance and remarkable self-healing properties. This unique blend of properties can be exploited to make soft optical devices from these gels. 相似文献
97.
98.
J.B. Kana Kana J.M. Ndjaka B.D. Ngom N. Manyala A.C. Beye 《Applied Surface Science》2008,254(13):3959-3963
The novel physical vapor deposition called inverted cylindrical magnetron sputtering (also known as hollow cathode sputtering) is commonly used to coat wires, fibers, ribbons as well as all sides of three-dimensional substrates. It is a reproducible method for the production of nano-structured systems onto complex shapes substrates. This paper reports the first synthesis and feasibility of reliably reproduced stoichiometric pure textured VO2 nano-structures by the rf-inverted cylindrical magnetron sputtering. Morphological, structural, elemental analysis and optical properties of synthesized VO2 under optimized conditions are reported. 相似文献
99.
Sureshan KM Murakami T Miyasou T Watanabe Y 《Journal of the American Chemical Society》2004,126(30):9174-9175
An unusual thermal isomerization of 1,2;3,4-di-O-isopropylidene-myo-inositol to 1,2;5,6-di-O-isopropylidene-myo-inositol was observed in the solid state. A detailed study revealed that this ketal migration is a topochemically driven one. X-ray structure revealed that strong intermolecular hydrogen bonding in the crystal preorganizes the hydroxyl and ketal carbon in a transition-state-like arrangement favorable for the reaction. The 5-OH of each molecule faces the trans ketal carbon of a neighboring molecule at a close distance and an angle of approach near to linearity, making a trigonal-bipyramidal-like arrangement in the crystal, which could facilitate the reaction. This is the first report of a topochemical transketalization reaction. 相似文献
100.
Miyake H Yoshida K Sugimoto H Tsukube H 《Journal of the American Chemical Society》2004,126(21):6524-6525
The helical chirality of a Co(II) complex with a chiral tetradentate ligand is completely inverted from Lambda to Delta by the addition of achiral NO3- anion as an external stimulus. 相似文献