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Salter PS Jesacher A Spring JB Metcalf BJ Thomas-Peter N Simmonds RD Langford NK Walmsley IA Booth MJ 《Optics letters》2012,37(4):470-472
We demonstrate an improved method for fabricating optical waveguides in bulk materials by means of femtosecond laser writing. We use an LC spatial light modulator (SLM) to shape the beam focus by generating adaptive slit illumination in the pupil of the objective lens. A diffraction grating is applied in a strip across the SLM to simulate a slit, with the first diffracted order mapped onto the pupil plane of the objective lens while the zeroth order is blocked. This technique enables real-time control of the beam-shaping parameters during writing, facilitating the fabrication of more complicated structures than is possible using nonadaptive methods. Waveguides are demonstrated in fused silica with a coupling loss to single-mode fibers in the range of 0.2 to 0.5 dB and propagation loss <0.4 dB/cm. 相似文献
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Woodyer RD Shao Z Thomas PM Kelleher NL Blodgett JA Metcalf WW van der Donk WA Zhao H 《Chemistry & biology》2006,13(11):1171-1182
Fosfomycin is a clinically utilized, highly effective antibiotic, which is active against methicillin- and vancomycin-resistant pathogens. Here we report the cloning and characterization of a complete fosfomycin biosynthetic cluster from Streptomyces fradiae and heterologous production of fosfomycin in S. lividans. Sequence analysis coupled with gene deletion and disruption revealed that the minimal cluster consists of fom1-4, fomA-D. A LuxR-type activator that was apparently required for heterologous fosfomycin production was also discovered approximately 13 kb away from the cluster and was named fomR. The genes fomE and fomF, previously thought to be involved in fosfomycin biosynthesis, were shown not to be essential by gene disruption. This work provides new insights into fosfomycin biosynthesis and opens the door for fosfomycin overproduction and creation of new analogs via biomolecular pathway engineering. 相似文献
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Co3O4纳米立方体的可控合成及其CO氧化反应性能 总被引:1,自引:0,他引:1
在乙醇和三乙胺的混合溶液中,采用溶剂热法制备了尺寸为10 nm的Co3O4立方体. 考察了钴盐前驱体和溶解氧对Co3O4纳米立方体结构的影响规律,通过对合成过程中不同阶段产物的结构分析和表征,提出了Co3O4纳米立方体的形成机制是溶解再结晶的过程. 将所制备的Co3O4纳米立方体在200 ℃焙烧处理后,尺寸和形貌均可保持稳定,但400 ℃焙烧后,变为球形纳米粒子. 这种主要暴露{100}晶面的Co3O4纳米立方体催化CO氧化反应的活性低于纳米粒子({111}晶面),验证了四氧化三钴纳米材料在CO氧化反应中的晶面效应. 相似文献
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The reaction of benzhnidazole methiodide with ethyl malonate in the existence of base was studied,and a new convenient synthetic method of the β-keto acid was provided. 相似文献
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Many lead compounds in the search for new drugs derive from peptides and polyketides whose similar biosynthetic enzymes have been difficult to engineer for production of new derivatives. Problems with generating multiple analogs in a single experiment along with lack of high-throughput methods for structure-based screening have slowed progress in this area. Here, we use directed evolution and a multiplexed assay to screen a library of >14,000 members to generate three derivatives of the antibacterial compound, andrimid. Another limiting factor in reengineering these mega-enzymes of secondary metabolism has been that commonly used hosts such as Escherichia coli often give lower product titers, so our reengineering was performed in the native producer, Pantoea agglomerans. This integrated in?vivo approach can be extended to larger enzymes to create analogs of natural products for bioactivity testing. 相似文献
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2013年5月2日至5日,第4届国际超声大会(ICU)在新加坡召开。本次会议在国际声学委员会的组织下,由新加坡声学学会主办,由澳大利亚声学学会、印度声学学会、香港声学学会和印度无损检测学会联合承办。会议致力于促进超声不同领域,包括基础研究、工程技术以及生物医学应用等方面的国际交流与合作。 相似文献