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排序方式: 共有157条查询结果,搜索用时 328 毫秒
71.
Mutations in DNAH5 cause primary ciliary dyskinesia and randomization of left-right asymmetry. 总被引:19,自引:0,他引:19
Heike Olbrich Karsten H?ffner Andreas Kispert Alexander V?lkel Andreas Volz Gürsel Sasmaz Richard Reinhardt Steffen Hennig Hans Lehrach Nikolaus Konietzko Maimoona Zariwala Peadar G Noone Michael Knowles Hannah M Mitchison Maggie Meeks Eddie M K Chung Friedhelm Hildebrandt Ralf Sudbrak Heymut Omran 《Nature genetics》2002,30(2):143-144
72.
In nature, helical macromolecules such as collagen, chitin and cellulose are critical to the morphogenesis and functionality of various hierarchically structured materials. During tissue formation, these chiral macromolecules are secreted and undergo self-templating assembly, a process whereby multiple kinetic factors influence the assembly of the incoming building blocks to produce non-equilibrium structures. A single macromolecule can form diverse functional structures when self-templated under different conditions. Collagen type I, for instance, forms transparent corneal tissues from orthogonally aligned nematic fibres, distinctively coloured skin tissues from cholesteric phase fibre bundles, and mineralized tissues from hierarchically organized fibres. Nature's self-templated materials surpass the functional and structural complexity achievable by current top-down and bottom-up fabrication methods. However, self-templating has not been thoroughly explored for engineering synthetic materials. Here we demonstrate the biomimetic, self-templating assembly of chiral colloidal particles (M13 phage) into functional materials. A single-step process produces long-range-ordered, supramolecular films showing multiple levels of hierarchical organization and helical twist. Three distinct supramolecular structures are created by this approach: nematic orthogonal twists, cholesteric helical ribbons and smectic helicolidal nanofilaments. Both chiral liquid crystalline phase transitions and competing interfacial forces at the interface are found to be critical factors in determining the morphology of the templated structures during assembly. The resulting materials show distinctive optical and photonic properties, functioning as chiral reflector/filters and structural colour matrices. In addition, M13 phages with genetically incorporated bioactive peptide ligands direct both soft and hard tissue growth in a hierarchically organized manner. Our assembly approach provides insight into the complexities of hierarchical assembly in nature and could be expanded to other chiral molecules to engineer sophisticated functional helical-twisted structures. 相似文献
73.
Suppression of inflammation by a synthetic histone mimic 总被引:1,自引:0,他引:1
Nicodeme E Jeffrey KL Schaefer U Beinke S Dewell S Chung CW Chandwani R Marazzi I Wilson P Coste H White J Kirilovsky J Rice CM Lora JM Prinjha RK Lee K Tarakhovsky A 《Nature》2010,468(7327):1119-1123
74.
Hyerim Han Sang Hyeon Koh Bo Young Han Yeong Jin Chung Sang Chul Shin 《南京林业大学学报(自然科学版)》2010,34(4):175-175
以往研究认为,2006年前在韩国唯一的传播松材线虫的天牛是松褐天牛,但是最近的研究发现云杉花墨天牛也能传播松材线虫。对于两种天牛携带和传播线虫种类,特别是对拟松材线虫的携带和传播途径需要进一步研究。拟松材线虫分为欧洲型和东亚型,在韩国两种生物型都存在。笔者的研究表明大部分云杉花墨天牛携带的是欧洲型的拟松材线虫。 相似文献
75.
Vinko SM Ciricosta O Cho BI Engelhorn K Chung HK Brown CR Burian T Chalupský J Falcone RW Graves C Hájková V Higginbotham A Juha L Krzywinski J Lee HJ Messerschmidt M Murphy CD Ping Y Scherz A Schlotter W Toleikis S Turner JJ Vysin L Wang T Wu B Zastrau U Zhu D Lee RW Heimann PA Nagler B Wark JS 《Nature》2012,482(7383):59-62
Matter with a high energy density (>10(5)?joules per cm(3)) is prevalent throughout the Universe, being present in all types of stars and towards the centre of the giant planets; it is also relevant for inertial confinement fusion. Its thermodynamic and transport properties are challenging to measure, requiring the creation of sufficiently long-lived samples at homogeneous temperatures and densities. With the advent of the Linac Coherent Light Source (LCLS) X-ray laser, high-intensity radiation (>10(17)?watts per cm(2), previously the domain of optical lasers) can be produced at X-ray wavelengths. The interaction of single atoms with such intense X-rays has recently been investigated. An understanding of the contrasting case of intense X-ray interaction with dense systems is important from a fundamental viewpoint and for applications. Here we report the experimental creation of a solid-density plasma at temperatures in excess of 10(6) kelvin on inertial-confinement timescales using an X-ray free-electron laser. We discuss the pertinent physics of the intense X-ray-matter interactions, and illustrate the importance of electron-ion collisions. Detailed simulations of the interaction process conducted with a radiative-collisional code show good qualitative agreement with the experimental results. We obtain insights into the evolution of the charge state distribution of the system, the electron density and temperature, and the timescales of collisional processes. Our results should inform future high-intensity X-ray experiments involving dense samples, such as X-ray diffractive imaging of biological systems, material science investigations, and the study of matter in extreme conditions. 相似文献
76.
Dye-sensitized solar cells based on titanium dioxide (TiO(2)) are promising low-cost alternatives to conventional solid-state photovoltaic devices based on materials such as Si, CdTe and CuIn(1-x)Ga(x)Se(2) (refs 1, 2). Despite offering relatively high conversion efficiencies for solar energy, typical dye-sensitized solar cells suffer from durability problems that result from their use of organic liquid electrolytes containing the iodide/tri-iodide redox couple, which causes serious problems such as electrode corrosion and electrolyte leakage. Replacements for iodine-based liquid electrolytes have been extensively studied, but the efficiencies of the resulting devices remain low. Here we show that the solution-processable p-type direct bandgap semiconductor CsSnI(3) can be used for hole conduction in lieu of a liquid electrolyte. The resulting solid-state dye-sensitized solar cells consist of CsSnI(2.95)F(0.05) doped with SnF(2), nanoporous TiO(2) and the dye N719, and show conversion efficiencies of up to 10.2 per cent (8.51 per cent with a mask). With a bandgap of 1.3 electronvolts, CsSnI(3) enhances visible light absorption on the red side of the spectrum to outperform the typical dye-sensitized solar cells in this spectral region. 相似文献
77.
78.
79.
Shot noise measurements have been used to measure the charge of quasiparticles in the fractional quantum Hall (FQH) regime. To induce shot noise in an otherwise noiseless current of quasiparticles, a barrier is placed in its path to cause weak backscattering. The measured shot noise is proportional to the charge of the quasiparticles; for example, at filling factor v=1/3, noise corresponding to q=e/3 appears. For increasingly opaque barriers, the measured charge increases monotonically, approaching q=e asymptotically. It was therefore believed that only electrons, or alternatively, three bunched quasiparticles, can tunnel through high-potential barriers encountered by a noiseless current of quasiparticles. Here we investigate the interaction of e/3 quasiparticles with a strong barrier in FQH samples and find that bunching of quasiparticles in the strong backscattering limit depends on the average dilution of the quasiparticle current. For a very dilute current, bunching ceases altogether and the transferred charge approaches q=e/3. This surprising result demonstrates that quasiparticles can tunnel individually through high-potential barriers originally thought to be opaque for them. 相似文献
80.
设f是紧度量空间上的连续自映射。本文证明,如果f的所有非渐近周期的非游荡点的集合的基数是可列的,则f的遍历测度是它的周期轨道原子测度,且f的拓扑熵为零。作为推论还得到,逐点周期映射有零拓扑熵。另外,当f没有周期点时,其非游荡点的集合的基数是不可列的。 相似文献