分类: 生物学 >> 生物物理学 提交时间: 2016-05-18
摘要: A novel amphiphilic homopolymer (PAGC(8)), containing two hydrophilic head groups and double hydrophobic tails in each repeat unit, has been prepared by solution polymerization and named as "a geminized amphiphilic homopolymer" in this paper, which is capable of self-assembling into various nanoobjects depending on the solution concentration and solvent properties. Characterization of the self-assembly behaviors was carried out by steady-state fluorescence, transmission electron microscopy and nuclear magnetic resonance techniques. Particular emphasis was dedicated to the environmental responsiveness of the assemblies. The morphologies were observed to transform from micelle-type to vesicles on adding a certain amount of ethanol. It is noteworthy that the assemblies were able to trap hydrophilic (rhodamine B) and hydrophobic (Sudan Red) molecules. Subsequently different nanoobjects were found after the encapsulation. To probe the effect of the topological structure on the self-assembly behaviors, the properties of an additional homopolymer with single charge pendant architecture on the backbone were investigated for comparison. Significant differences in structure between the two architectures brought out remarkable variations in aggregates, which were non-responsive to the solvent environment, or encapsulation of molecules. Based on the experimental results, we proposed a possible mechanism of the morphological transitions of the assemblies.
分类: 核科学技术 >> 核探测技术与核电子学 提交时间: 2023-06-18 合作期刊: 《Nuclear Science and Techniques》
摘要: Hefei Light Source (HLS)-II is a vacuum ultraviole (VUV) synchrotron light source. A major upgrade of the light source was finished at the end of 2014. The timing system was rebuilt using compact peripheral component interconnect (cPCI) event-driven hardware to meet synchronization requirements of the machine. In the new system, the cPCI event-driven products manufactured by the micro-research finland (MRF) Oy are employed to achieve about 100 output signals with different interfaces. Device supports and drivers developed for common Experimental Physics and Industrial Control System (EPICS) records are used to access the registers on the timing modules. Five cPCI-bus input/output controllers (IOCs) distributed in different areas of the light source host timing modules for various subsystems. The delay resolution of this system is 9.8 ns for most channels and 9 ps for the channels used for triggering the electron gun and the injection kickers. The measured rms jitter of the output signal is less than 27 ps. Using the bucket chooser, this system enables the HLS-II to fill the storage ring with any designated bunch pattern. Benefitting from this upgrade, brightness and performance of the light source are significantly improved.
分类: 生物学 >> 生物物理学 提交时间: 2016-05-11
摘要: Maize chlorotic mottle virus (MCMV) is the only member of the Machlomovirus genus in the family Tombusviridae. Here, we obtained the Cryo-EM structure of MCMV by single particle analysis with most local resolution at approximately 4 angstrom. The C alpha backbone was built based on residues with bulky side chains. The resolved C-terminus of the capsid protein subunit and obvious openings at the 2-fold axis demonstrated the compactness of the asymmetric unit, which indicates an important role in the stability of MCMV. The Asp116 residue from each subunit around the 5-fold and 3-fold axes contributed to the negative charges in the centers of the pentamers and hexamers, which might serve as a solid barrier against the leakage of genomic RNA. Finally, the loops most exposed on the surface were analyzed and are proposed to be potential functional sites related to MCMV transmission. (C) 2015 Elsevier Inc. All rights reserved.