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RISS 인기검색어
- 검색키워드
- 저자 : Alyssa Matthews (검색결과 3 건)
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Cooperative self-assembly: producing synthetic polymers with precise and concise primary structures
Avestro, Alyssa-Jennifer,Belowich, Matthew E.,Stoddart, J. Fraser The Royal Society of Chemistry 2012 Chemical Society reviews Vol.41 No.18
<P>The quest to construct mechanically interlocked polymers, which present precise monodisperse primary structures that are produced both consistently and with high efficiencies, has been a daunting goal for synthetic chemists for many years. Our ability to realise this goal has been limited, until recently, by the need to develop synthetic strategies that can direct the formation of the desired covalent bonds in a precise and concise fashion while avoiding the formation of unwanted kinetic by-products. The challenge, however, is a timely and welcome one, as a consequence of, primarily, the potential for mechanically interlocked polymers to act as dynamic (noncovalent) yet robust (covalent) new materials for a wide array of applications. One such strategy which has been employed widely in recent years to address this issue, known as Dynamic Covalent Chemistry (DCC), is a strategy in which reactions operate under equilibrium and so offer elements of “proof-reading” and “error-checking” to the bond forming and breaking processes such that the final product distribution always reflects the thermodynamically most favourable compound. By coupling DCC with template-directed protocols, which utilise multiple weak noncovalent interactions to pre-organise and self-assemble simpler small molecular precursors into their desired geometries prior to covalent bond formation, we are able to produce compounds with highly symmetric, robust and complex topologies that are otherwise simply unobtainable by more traditional methods. Harnessing these strategies in an iterative, step-wise fashion brings us ever so much closer towards perfecting the controlled synthesis of high order main-chain mechanically interlocked polymers. This <I>tutorial review</I> focuses (i) on the development of DCC—namely, the formation of dynamic imine bonds—used in conjunction with template-directed protocols to afford a variety of mechanically interlocked molecules (MIMs) and ultimately (ii) on the synthesis of highly ordered poly[<I>n</I>]rotaxanes with high conversion efficiencies.</P> <P>Graphic Abstract</P><P>Emergent positive cooperativity accelerates the efficient template-directed assembly of mechanically interlocked molecules with contiguous [π···π] stacks in high yields. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c2cs35167f'> </P>
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Diagnosis and Management of Gastric Intestinal Metaplasia: Current Status and Future Directions
Robert J. Huang,Alyssa Y. Choi,Camtu D. Truong,Matthew M. Yeh,Joo Ha Hwang 거트앤리버 소화기연관학회협의회 2019 Gut and Liver Vol.13 No.6
Gastric intestinal metaplasia (GIM) is a known premalignant condition of the human stomach along the pathway to gastric cancer (GC). Histologically, GIM represents the replacement of normal gastric mucosa by mucin-secreting intestinal mucosa. Helicobacter pylori infection is the most common etiologic agent of GIM development worldwide. The prevalence of GIM is heterogeneous among different regions of the world and correlates with the population endemicity of H. pylori carriage, among other environmental factors. GC remains the third leading cause of cancer-related mortality globally. GIM is usually diagnosed by upper endoscopy with biopsy, and histologic scoring systems have been developed to riskstratify patients at highest risk for progression to GC. Several recent endoscopic imaging modalities may improve the optical detection of GIM and early GC. Appropriate surveillance of GIM may be cost effective and represents an opportunity for the early diagnosis and therapy of GC. Certain East Asian nations have established population-level programs for the screening and surveillance of GIM; guidelines regarding GIM surveillance have also recently been published in Europe. By contrast, few data exist regarding the appropriateness of surveillance of GIM in the United States. In this review, we discuss the pathogenesis, epidemiology, diagnosis, and management of GIM with an emphasis on the role of appropriate endoscopic surveillance.
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