Thermal fluctuations and x-ray scattering from free-standing smectic-Afilms

2000 ◽  
Vol 62 (1) ◽  
pp. 647-657 ◽  
Author(s):  
L. V. Mirantsev
1996 ◽  
Vol 54 (1) ◽  
pp. 536-549 ◽  
Author(s):  
E. A. L. Mol ◽  
J. D. Shindler ◽  
A. N. Shalaginov ◽  
W. H. de Jeu

1999 ◽  
Vol 86 (12) ◽  
pp. 6763-6769 ◽  
Author(s):  
Markus Rauscher ◽  
Rogerio Paniago ◽  
Hartmut Metzger ◽  
Zoltan Kovats ◽  
Jan Domke ◽  
...  

2000 ◽  
Vol 76 (14) ◽  
pp. 1863-1865 ◽  
Author(s):  
L. S. Matkin ◽  
H. F. Gleeson ◽  
P. Mach ◽  
C. C. Huang ◽  
R. Pindak ◽  
...  

2000 ◽  
Vol 62 (11) ◽  
pp. 7229-7236 ◽  
Author(s):  
J. Stangl ◽  
V. Holý ◽  
T. Roch ◽  
A. Daniel ◽  
G. Bauer ◽  
...  

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Xunliang Hu ◽  
Zhen Zhan ◽  
Jianqiao Zhang ◽  
Irshad Hussain ◽  
Bien Tan

AbstractCovalent triazine frameworks have recently been demonstrated as promising materials for photocatalytic water splitting and are usually used in the form of suspended powder. From a practical point of view, immobilized CTFs materials are more suitable for large-scale water splitting, owing to their convenient separation and recycling potential. However, existing synthetic approaches mainly result in insoluble and unprocessable powders, which make their future device application a formidable challenge. Herein, we report an aliphatic amine-assisted interfacial polymerization method to obtain free-standing, semicrystalline CTFs film with excellent photoelectric performance. The lateral size of the film was up to 250 cm2, and average thickness can be tuned from 30 to 500 nm. The semicrystalline structure was confirmed by high-resolution transmission electron microscope, powder X-ray diffraction, grazing-incidence wide-angle X-ray scattering, and small-angle X-ray scattering analysis. Intrigued by the good light absorption, crystalline structure, and large lateral size of the film, the film immobilized on a glass support exhibited good photocatalytic hydrogen evolution performance (5.4 mmol h−1 m−2) with the presence of co-catalysts i.e., Pt nanoparticles and was easy to recycle.


2018 ◽  
Vol 9 (01) ◽  
pp. 224-228 ◽  
Author(s):  
Dan Ye ◽  
Sintu Rongpipi ◽  
Joshua H. Litofsky ◽  
Youngmin Lee ◽  
Tyler E. Culp ◽  
...  

Abstract


Author(s):  
Eva-Maria Mandelkow ◽  
Eckhard Mandelkow ◽  
Joan Bordas

When a solution of microtubule protein is changed from non-polymerising to polymerising conditions (e.g. by temperature jump or mixing with GTP) there is a series of structural transitions preceding microtubule growth. These have been detected by time-resolved X-ray scattering using synchrotron radiation, and they may be classified into pre-nucleation and nucleation events. X-ray patterns are good indicators for the average behavior of the particles in solution, but they are difficult to interpret unless additional information on their structure is available. We therefore studied the assembly process by electron microscopy under conditions approaching those of the X-ray experiment. There are two difficulties in the EM approach: One is that the particles important for assembly are usually small and not very regular and therefore tend to be overlooked. Secondly EM specimens require low concentrations which favor disassembly of the particles one wants to observe since there is a dynamic equilibrium between polymers and subunits.


Author(s):  
Eva-Maria Mandelkow ◽  
Ron Milligan

Microtubules form part of the cytoskeleton of eukaryotic cells. They are hollow libers of about 25 nm diameter made up of 13 protofilaments, each of which consists of a chain of heterodimers of α-and β-tubulin. Microtubules can be assembled in vitro at 37°C in the presence of GTP which is hydrolyzed during the reaction, and they are disassembled at 4°C. In contrast to most other polymers microtubules show the behavior of “dynamic instability”, i.e. they can switch between phases of growth and phases of shrinkage, even at an overall steady state [1]. In certain conditions an entire solution can be synchronized, leading to autonomous oscillations in the degree of assembly which can be observed by X-ray scattering (Fig. 1), light scattering, or electron microscopy [2-5]. In addition such solutions are capable of generating spontaneous spatial patterns [6].In an earlier study we have analyzed the structure of microtubules and their cold-induced disassembly by cryo-EM [7]. One result was that disassembly takes place by loss of protofilament fragments (tubulin oligomers) which fray apart at the microtubule ends. We also looked at microtubule oscillations by time-resolved X-ray scattering and proposed a reaction scheme [4] which involves a cyclic interconversion of tubulin, microtubules, and oligomers (Fig. 2). The present study was undertaken to answer two questions: (a) What is the nature of the oscillations as seen by time-resolved cryo-EM? (b) Do microtubules disassemble by fraying protofilament fragments during oscillations at 37°C?


1992 ◽  
Vol 2 (6) ◽  
pp. 899-913 ◽  
Author(s):  
Patrick Davidson ◽  
Elisabeth Dubois-Violette ◽  
Anne-Marie Levelut ◽  
Brigitte Pansu

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