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101.
Ronald Millett Henry Schriemer Trevor Hall Karin Hinzer 《Optical and Quantum Electronics》2008,40(14-15):1239-1245
We demonstrate the results of an analysis of laterally coupled distributed feedback (LC-DFB) lasers with higher order gratings, including the effects of radiating partial waves. For a given fabrication resolution, first-order gratings, if they can be reliably manufactured, always provide the strongest coupling. However, at resolutions requiring higher order gratings, if duty cycles of >0.5 are used, the lowest grating order is not always the one with the strongest coupling. An analysis of the rounding of the grating teeth showed that the required threshold gain was increased by nearly 20% when the rectangular grating was rounded in fabrication. 相似文献
102.
Given a multiplicative band of idempotents S in a ring R, for all e,f∈S the ∇-product e
∇
f=e+f+fe−efe−fef is an idempotent that lies roughly above e and f in R just as ef and fe lie roughly below e and f. In this paper we study ∇-bands in rings, that is, bands in rings that are closed under ∇, giving various criteria for ∇ to be associative, thus making the band a skew lattice. We also consider when a given band S in R generates a ∇-band. 相似文献
103.
Karin Odelius Ann‐Christine Albertsson 《Journal of polymer science. Part A, Polymer chemistry》2008,46(4):1249-1264
Star‐shaped homo‐ and copolymers were synthesized in a controlled fashion using two different initiating systems. Homopolymers of ε‐caprolactone, L ‐lactide, and 1,5‐dioxepan‐2‐one were firstly polymerized using (I) a spirocyclic tin initiator and (II) stannous octoate (cocatalyst) together with pentaerythritol ethoxylate 15/4 EO/OH (coinitiator), to give polymers with identical core moieties. Our gained understanding of the versatile and controllable initiator systems kinetics, the transesterification reactions occurring, and the role which the reaction conditions play on the material outcome, made it possible to tailor the copolymer microstructure. Two strategies were used to successfully synthesize copolymers of different microstructures with the two initiator systems, i.e., a more multiblock‐ or a block‐structure. The correct choice of the monomer addition order enabled two distinct blocks to be created for the copolymers of poly(DXO‐co‐LLA) and poly(CL‐co‐LLA). In the case of poly(CL‐co‐DXO), multiblock copolymers were created using both systems whereas longer blocks were created with the spirocyclic tin initiator. © 2008 Wiley Periodicals, Inc. JPolym Sci Part A: Polym Chem 46: 1249–1264, 2008 相似文献
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Erythromycin A is a potent antibiotic long-recognized as a therapeutic option for bacterial infections. The soil-dwelling bacterium Saccharopolyspora erythraea natively produces erythromycin A from a 55 kb gene cluster composed of three large polyketide synthase genes (each ~10 kb) and 17 additional genes responsible for deoxysugar biosynthesis, macrolide tailoring, and resistance. In this study, the erythromycin A gene cluster was systematically transferred from S. erythraea to E. coli for reconstituted biosynthesis, with titers reaching 10 mg/l. Polyketide biosynthesis was then modified to allow the production of two erythromycin analogs. Success establishes E. coli as a viable option for the heterologous production of erythromycin A and more broadly as a platform for the directed production of erythromycin analogs. 相似文献
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109.
Karin Erdmann 《Linear algebra and its applications》2011,434(12):2475-2496
In this paper we evaluate Chebyshev polynomials of the second kind on a class of symmetric integer matrices, namely on adjacency matrices of simply laced Dynkin and extended Dynkin diagrams. As an application of these results we explicitly calculate minimal projective resolutions of simple modules of symmetric algebras with radical cube zero that are of finite and tame representation type. 相似文献
110.