http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
- 中文 을 입력하시려면 zhongwen을 입력하시고 space를누르시면됩니다.
- 北京 을 입력하시려면 beijing을 입력하시고 space를 누르시면 됩니다.
RISS 인기검색어
- 검색키워드
- 저자 : Kieffer, Robert (검색결과 4 건)
- 무료
- 기관 내 무료
- 유료
-
Complex Multicolor Tilings and Critical Phenomena in Tetraphilic Liquid Crystals
Zeng, X.,Kieffer, R.,Glettner, B.,Nurnberger, C.,Liu, F.,Pelz, K.,Prehm, M.,Baumeister, U.,Hahn, H.,Lang, H.,Gehring, G. A.,Weber, C. H. M.,Hobbs, J. K.,Tschierske, C.,Ungar, G. American Association for the Advancement of Scienc 2011 Science Vol.331 No.6022
<P>T-shaped molecules with a rod-like aromatic core and a flexible side chain form liquid crystal honeycombs with aromatic cell walls and a cell interior filled with the side chains. Here, we show how the addition of a second chain, incompatible with the first (X-shaped molecules), can form honeycombs with highly complex tiling patterns, with cells of up to five different compositions ('colors') and polygonal shapes. The complexity is caused by the inability of the side chains to separate cleanly because of geometric frustration. Furthermore, a thermoreversible transition was observed between a multicolor (phase-separated) and a single-color (mixed) honeycomb phase. This is analogous to the Curie transition in simple and frustrated ferro- and antiferromagnets; here spin flips are replaced by 180° reorientations of the molecules.</P>
-
-
조영민,Rhonda D. Wideman,Timothy J. Kieffer 대한내분비학회 2013 Endocrinology and metabolism Vol.28 No.4
Glucagon-like peptide 1 (GLP-1) is secreted from enteroendocrine L-cells in response to oral nutrient intake and elicits glucosestimulated insulin secretion while suppressing glucagon secretion. It also slows gastric emptying, which contributes to decreased postprandial glycemic excursions. In the 1990s, chronic subcutaneous infusion of GLP-1 was found to lower blood glucose levels in patients with type 2 diabetes. However, GLP-1’s very short half-life, arising from cleavage by the enzyme dipeptidyl peptidase 4 (DPP-4) and glomerular filtration by the kidneys, presented challenges for clinical use. Hence, DPP-4 inhibitors were developed,as well as several GLP-1 analogs engineered to circumvent DPP-4-mediated breakdown and/or rapid renal elimination. Three categories of GLP-1 analogs, are being developed and/or are in clinical use: short-acting, long-acting, and prolonged-acting GLP-1 analogs. Each class has different plasma half-lives, molecular size, and homology to native GLP-1, and consequently different characteristic effects on glucose metabolism. In this article, we review current clinical data derived from each class of GLP-1 analogs, and consider the clinical effects reported for each category in recent head to head comparison studies. Given the relatively brief clinical history of these compounds, we also highlight several important efficacy and safety issues which will require further investigation.
-
Ungar, Goran,Tschierske, Carsten,Abetz, Volker,Holyst, Robert,Bates, Martin A.,Liu, Feng,Prehm, Marko,Kieffer, Robert,Zeng, Xiangbing,Walker, Martin,Glettner, Benjamin,Zywocinski, Andrzej WILEY‐VCH Verlag 2011 Advanced functional materials Vol.21 No.7
<P><B>Abstract</B></P><P>The diversity of phase morphologies observed recently in star‐branched liquid‐crystalline and polymeric compounds containing at least three immiscible segments is reviewed. Bolaamphiphiles and facial amphiphiles with rodlike aromatic cores, two end‐groups, and one (T‐shape) or two (X‐shape) chains attached laterally to the core, form numerous honeycomblike liquid‐crystal phases, as well as a variety of novel lamellar and 3D‐ordered mesophases. Molecular self‐organization is described in bulk phases and in thin films on solid and liquid surfaces, as well as in Langmuir–Blodgett films. The remarkably reversible formation of mono‐ and trilayer films is highlighted. In the bulk, T‐shaped “rod–coil” molecules without appended end‐groups form predominantly lamellar phases if the core is a straight rod, but the bent‐core variety forms hexagonal honeycombs. Furthermore, self‐assembly of “Janus”‐type molecules, is discussed. Also covered is the diversity of morphologies observed in miktoarm star terpolymers, i.e., polymers with three different and incompatible arms of well defined lengths. Similarities and differences are highlighted between the liquid‐crystal morphologies on the 3–15 nm scale and the polymer morphologies on the scale of 10–100 nm. A separate section is dedicated to computer simulations of such systems, particularly those using dissipative particle and molecular dynamics. Of special interest are the recently synthesised X‐shaped tetraphilic molecules, where two different and incompatible side‐chains are attached at opposite sides of the rodlike core. The tendency for their phase separation produces liquid‐crystal honeycombs with cells of different compositions that can be represented as a plane paved with different colored tiles. The independent variation of chain length and “color” creates the potential for developing a considerable range of complex new 2D and 3D soft nanostructures. Analogous X‐shaped rod–coil compounds with unequal side groups are also of considerable interest, forming tubular lyotropic structures capable of confining strings of guest molecules.</P>
연관 검색어 추천
이 검색어로 많이 본 자료
활용도 높은 자료
