Zeitschriftenartikel: „Assembly characterization“

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Ghosh, Tarini Shankar, Varun Mehra und Sharmila S. Mande. „Grid-Assembly: An oligonucleotide composition-based partitioning strategy to aid metagenomic sequence assembly“. Journal of Bioinformatics and Computational Biology 13, Nr. 03 (15.05.2015): 1541004. http://dx.doi.org/10.1142/s0219720015410048.

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Metagenomics approach involves extraction, sequencing and characterization of the genomic content of entire community of microbes present in a given environment. In contrast to genomic data, accurate assembly of metagenomic sequences is a challenging task. Given the huge volume and the diverse taxonomic origin of metagenomic sequences, direct application of single genome assembly methods on metagenomes are likely to not only lead to an immense increase in requirements of computational infrastructure, but also result in the formation of chimeric contigs. A strategy to address the above challenge would be to partition metagenomic sequence datasets into clusters and assemble separately the sequences in individual clusters using any single-genome assembly method. The current study presents such an approach that uses tetranucleotide usage patterns to first represent sequences as points in a three dimensional (3D) space. The 3D space is subsequently partitioned into "Grids". Sequences within overlapping grids are then progressively assembled using any available assembler. We demonstrate the applicability of the current Grid-Assembly method using various categories of assemblers as well as different simulated metagenomic datasets. Validation results indicate that the Grid-Assembly approach helps in improving the overall quality of assembly, in terms of the purity and volume of the assembled contigs.

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Delbianco, Martina, und Peter H. Seeberger. „Materials science based on synthetic polysaccharides“. Materials Horizons 7, Nr. 4 (2020): 963–69. http://dx.doi.org/10.1039/c9mh01936g.

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Robb, Bruce W., Hiroshi Wachi, Theresa Schaub, Robert P. Mecham und Elaine C. Davis. „Characterization of an In Vitro Model of Elastic Fiber Assembly“. Molecular Biology of the Cell 10, Nr. 11 (November 1999): 3595–605. http://dx.doi.org/10.1091/mbc.10.11.3595.

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Elastic fibers consist of two morphologically distinct components: elastin and 10-nm fibrillin-containing microfibrils. During development, the microfibrils form bundles that appear to act as a scaffold for the deposition, orientation, and assembly of tropoelastin monomers into an insoluble elastic fiber. Although microfibrils can assemble independent of elastin, tropoelastin monomers do not assemble without the presence of microfibrils. In the present study, immortalized ciliary body pigmented epithelial (PE) cells were investigated for their potential to serve as a cell culture model for elastic fiber assembly. Northern analysis showed that the PE cells express microfibril proteins but do not express tropoelastin. Immunofluorescence staining and electron microscopy confirmed that the microfibril proteins produced by the PE cells assemble into intact microfibrils. When the PE cells were transfected with a mammalian expression vector containing a bovine tropoelastin cDNA, the cells were found to express and secrete tropoelastin. Immunofluorescence and electron microscopic examination of the transfected PE cells showed the presence of elastic fibers in the matrix. Biochemical analysis of this matrix showed the presence of cross-links that are unique to mature insoluble elastin. Together, these results indicate that the PE cells provide a unique, stable in vitro system in which to study elastic fiber assembly.

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Clévy, Cédric, Ion Lungu, Kanty Rabenorosoa und Philippe Lutz. „Positioning accuracy characterization of assembled microscale components for micro-optical benches“. Assembly Automation 34, Nr. 1 (28.01.2014): 69–77. http://dx.doi.org/10.1108/aa-02-2013-011.

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Purpose – This paper aims to deal with the measurement of positioning accuracies of microscale components assembled to fabricate micro-optical benches (MOB). Design/methodology/approach – The concept of MOB is presented to explain how to fabricate optical MEMS based on out-of-plane micro-assembly of microcomponents. This micro-assembly platform includes a laser sensor that enables to measure the position of the microcomponent after its assembly. The measurement set-up and procedure is displayed and applied on several micro-assembly sets. Findings – The measurement system provides results with maximum deviation smaller than ±0.005°. Based on this measurement system and micro-assembly procedure displayed in the article, it is shown that it is possible to obtain a positioning accuracy up to 0.009°. Originality/value – These results clearly show that micro-assembly is a possible way to fabricate complex, heterogeneous and 3D optical MEMS with very good optical performances.

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Liu, Xiao Jun, Li Yun Song, Zong Cheng Zhan, Hong He, Xue Hong Zi und Wen Ge Qiu. „2D Assembly of Palladium Nanoparticles and AFM Characterization“. Advanced Materials Research 887-888 (Februar 2014): 161–66. http://dx.doi.org/10.4028/www.scientific.net/amr.887-888.161.

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The two-dimensional (2D) assembly of the palladium nanoparticles (Pd NPs) was studied in this work. The cubic Pd NPs were successfully synthesized and assembled on mica and silicon wafer in the dip-coating way. The morphology of the Pd NPs and the topography of the Pd NPs assembly on the substrates were characterized with transmission electron microscopy (TEM) and atomic force microscopy (AFM). In the process of the fabrication, the excess cetyltrimethylammonium bromide (CTAB) was removed with the deposition-redispersion strategy, the UV-vis spectra and zeta-potential of the Pd NPs colloid were measured. It was found that the assembly and AFM characterization of the Pd NPs were affected negatively by the presence of excess CTAB. The hydrophilic property of the substrate is the crucial factor to control the 2D assembly of the Pd NPs. Compared with the washed silicon wafer, mica is ultra-hydrophilic and can attract more Pd NPs.

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Li, Cai Xia, Qing Lv, Jie Song, Dan Yu Jiang und Qiang Li. „Preparation and Characterization of Nano-Films Materials“. Key Engineering Materials 492 (September 2011): 160–63. http://dx.doi.org/10.4028/www.scientific.net/kem.492.160.

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Nano-sheets are two-dimensional sheet materials exfoliated from the inorganic layered compounds by various physical and chemical methods. Their unique characteristics insertion reaction and excellent physical and chemical properties have attracted more and more researchers' widespread interests. Selecting quartz glass as the substrate, using layer by layer self-assembly technology, different nano-films materials are prepared. UV/Vis spectroscopy confirmed nano-films materials have been successfully assembled using LBL self-assembly technique. Raman spectrum are mainly used to analyze and characterize the structure of nano-films materials.

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Reyes-Aldrete, Emilio, Erik A. Dill, Cecile Bussetta, Michal R. Szymanski, Geoffrey Diemer, Priyank Maindola, Mark A. White, Wlodzimierz M. Bujalowski, Kyung H. Choi und Marc C. Morais. „Biochemical and Biophysical Characterization of the dsDNA Packaging Motor from the Lactococcus lactis Bacteriophage Asccphi28“. Viruses 13, Nr. 1 (23.12.2020): 15. http://dx.doi.org/10.3390/v13010015.

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Double-stranded DNA viruses package their genomes into pre-assembled protein procapsids. This process is driven by macromolecular motors that transiently assemble at a unique vertex of the procapsid and utilize homomeric ring ATPases to couple genome encapsidation to ATP hydrolysis. Here, we describe the biochemical and biophysical characterization of the packaging ATPase from Lactococcus lactis phage asccφ28. Size-exclusion chromatography (SEC), analytical ultracentrifugation (AUC), small angle X-ray scattering (SAXS), and negative stain transmission electron microscopy (TEM) indicate that the ~45 kDa protein formed a 443 kDa cylindrical assembly with a maximum dimension of ~155 Å and radius of gyration of ~54 Å. Together with the dimensions of the crystallographic asymmetric unit from preliminary X-ray diffraction experiments, these results indicate that gp11 forms a decameric D5-symmetric complex consisting of two pentameric rings related by 2-fold symmetry. Additional kinetic analysis shows that recombinantly expressed gp11 has ATPase activity comparable to that of functional ATPase rings assembled on procapsids in other genome packaging systems. Hence, gp11 forms rings in solution that likely reflect the fully assembled ATPases in active virus-bound motor complexes. Whereas ATPase functionality in other double-stranded DNA (dsDNA) phage packaging systems requires assembly on viral capsids, the ability to form functional rings in solution imparts gp11 with significant advantages for high-resolution structural studies and rigorous biophysical/biochemical analysis.

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Yu, Fang, Swati M. Joshi, Yu May Ma, Richard L. Kingston, Martha N. Simon und Volker M. Vogt. „Characterization of Rous Sarcoma Virus Gag Particles Assembled In Vitro“. Journal of Virology 75, Nr. 6 (15.03.2001): 2753–64. http://dx.doi.org/10.1128/jvi.75.6.2753-2764.2001.

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ABSTRACT Purified retrovirus Gag proteins or Gag protein fragments are able to assemble into virus-like particles (VLPs) in vitro in the presence of RNA. We have examined the role of nucleic acid and of the NC domain in assembly of VLPs from a Rous sarcoma virus (RSV) Gag protein and have characterized these VLPs using transmission electron microscopy (TEM), scanning TEM (STEM), and cryoelectron microscopy (cryo-EM). RNAs of diverse sizes, single-stranded DNA oligonucleotides as small as 22 nucleotides, double-stranded DNA, and heparin all promoted efficient assembly. The percentages of nucleic acid by mass, in the VLPs varied from 5 to 8%. The mean mass of VLPs, as determined by STEM, was 6.5 × 107 Da for both RNA-containing and DNA oligonucleotide-containing particles, corresponding to a stoichiometry of about 1,200 protein molecules per VLP, slightly lower than the 1,500 Gag molecules estimated previously for infectious RSV. By cryo-EM, the VLPs showed the characteristic morphology of immature retroviruses, with discernible regions of high density corresponding to the two domains of the CA protein. In spherically averaged density distributions, the mean radial distance to the density corresponding to the C-terminal domain of CA was 33 nm, considerably smaller than that of equivalent human immunodeficiency virus type 1 particles. Deletions of the distal portion of NC, including the second Zn-binding motif, had little effect on assembly, but deletions including the charged residues between the two Zn-binding motifs abrogated assembly. Mutation of the cysteine and histidine residues in the first Zn-binding motif to alanine did not affect assembly, but mutation of the basic residues between the two Zn-binding motifs, or of the basic residues in the N-terminal portion of NC, abrogated assembly. Together, these findings establish VLPs as a good model for immature virions and establish a foundation for dissection of the interactions that lead to assembly.

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Cervantes-Salguero, Keitel, Yair Augusto Gutiérrez Fosado, William Megone, Julien E. Gautrot und Matteo Palma. „Programmed Self-Assembly of DNA Nanosheets with Discrete Single-Molecule Thickness and Interfacial Mechanics: Design, Simulation, and Characterization“. Molecules 28, Nr. 9 (24.04.2023): 3686. http://dx.doi.org/10.3390/molecules28093686.

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DNA is programmed to hierarchically self-assemble into superstructures spanning from nanometer to micrometer scales. Here, we demonstrate DNA nanosheets assembled out of a rationally designed flexible DNA unit (F-unit), whose shape resembles a Feynman diagram. F-units were designed to self-assemble in two dimensions and to display a high DNA density of hydrophobic moieties. oxDNA simulations confirmed the planarity of the F-unit. DNA nanosheets with a thickness of a single DNA duplex layer and with large coverage (at least 30 μm × 30 μm) were assembled from the liquid phase at the solid/liquid interface, as unambiguously evidenced by atomic force microscopy imaging. Interestingly, single-layer nanodiscs formed in solution at low DNA concentrations. DNA nanosheet superstructures were further assembled at liquid/liquid interfaces, as demonstrated by the fluorescence of a double-stranded DNA intercalator. Moreover, the interfacial mechanical properties of the nanosheet superstructures were measured as a response to temperature changes, demonstrating the control of interfacial shear mechanics based on DNA nanostructure engineering. The rational design of the F-unit, along with the presented results, provide an avenue toward the controlled assembly of reconfigurable/responsive nanosheets and membranes at liquid/liquid interfaces, to be potentially used in the characterization of biomechanical processes and materials transport.

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Chen, Hui, Xiao Hui Wang, Dong Li, Yan Zhu Guo und Run Cang Sun. „Preparation and Characterization of Quaternary Chitosan/sodium Alginate Self-Assembled Microcapsules“. Advanced Materials Research 554-556 (Juli 2012): 263–67. http://dx.doi.org/10.4028/www.scientific.net/amr.554-556.263.

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Biocompatible quaternary chitosan/sodium alginate multilayer microcapsules were prepared by layer-by-layer (LBL) self-assembly on the template of monodispersed melamine formaldehyde resin microspheres (MF). The process of self-assembly was monitored by measuring the surface zeta-potential of colloidal particles. The particle size was determined by digital light scattering (DLS) after each deposition, and the average thickness of monolayer film was revealed to be 3.9 nm. Using rhodamine B-labeled quaternary chitosan as the positive polyelectrolyte and sodium alginate as the negative polyelectrolyte, self-assembled multilayer microcapsules with strong red-light emitting were obtained and observed with fluorescence microscope. The fluorescent microcapsules self-assembled from the biocompatible natural polysaccharides may be potentially applied in drug delivery and fluorescence diagnosis.

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Carlotto, J. I., P. Fernandez-Martinez, S. Terzo, J. T. Gonzalez und S. Grinstein. „Characterization of the first RD53A triplet modules assembled at IFAE“. Journal of Instrumentation 17, Nr. 10 (01.10.2022): C10018. http://dx.doi.org/10.1088/1748-0221/17/10/c10018.

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Abstract IFAE is engaged in the production of linear triplet modules for the forthcoming upgrade of the Inner Tracker for the high luminosity phase of the Large Hadron Collider. The pre-production process requires the fabrication of early prototypes (the RD53A chip) to inform the assembly and electrical test methodologies. Module prototypes (also called triplets) include a set of 3 hybrids (sensors connected to readout chips), all of them are mounted in an individual flexible PCB. This document presents the assembly methodologies and main electrical tests results for the first set of 4 modules assembled at IFAE.

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Rybka, Jakub, Adam Mieloch, Alicja Plis, Marcin Pyrski, Tomasz Pniewski und Michael Giersig. „Assembly and Characterization of HBc Derived Virus-like Particles with Magnetic Core“. Nanomaterials 9, Nr. 2 (26.01.2019): 155. http://dx.doi.org/10.3390/nano9020155.

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Core-virus like particles (VLPs) assembly is a kinetically complex cascade of interactions between viral proteins, nanoparticle’s surface and an ionic environment. Despite many in silico simulations regarding this process, there is still a lack of experimental data. The main goal of this study was to investigate the capsid protein of hepatitis B virus (HBc) assembly into virus-like particles with superparamagnetic iron oxide nanoparticles (SPIONs) as a magnetic core in relation to their characteristics. The native form of HBc was obtained via agroinfection of Nicotiana benthamiana with pEAQ-HBc plasmid. SPIONs of diameter of 15 nm were synthesized and functionalized with two ligands, providing variety in ζ-potential and hydrodynamic diameter. The antigenic potential of the assembled core-VLPs was assessed with enzyme-linked immunosorbent assay (ELISA). Morphology of SPIONs and core-VLPs was evaluated via transmission electron microscopy (TEM). The most successful core-VLPs assembly was obtained for SPIONs functionalized with dihexadecyl phosphate (DHP) at SPIONs/HBc ratio of 0.2/0.05 mg/mL. ELISA results indicate significant decrease of antigenicity concomitant with core-VLPs assembly. In summary, this study provides an experimental assessment of the crucial parameters guiding SPION-HBc VLPs assembly and evaluates the antigenicity of the obtained structures.

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Wang, Yi, und Graciela W. Padua. „Nanoscale Characterization of Zein Self-Assembly“. Langmuir 28, Nr. 5 (20.01.2012): 2429–35. http://dx.doi.org/10.1021/la204204j.

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Dalton, S., und B. Hopwood. „Characterization of Cdc47p-minichromosome maintenance complexes in Saccharomyces cerevisiae: identification of Cdc45p as a subunit.“ Molecular and Cellular Biology 17, Nr. 10 (Oktober 1997): 5867–75. http://dx.doi.org/10.1128/mcb.17.10.5867.

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Cdc47p is a member of the minichromosome maintenance (MCM) family of polypeptides, which have a role in the early stages of chromosomal DNA replication. Here, we show that Cdc47p assembles into stable complexes with two other members of the MCM family, Cdc46p and Mcm3p. The assembly of Cdc47p into complexes with Cdc46p does not appear to be cell cycle regulated, making it unlikely that these interactions per se are a rate-limiting step in the control of S phase. Cdc45p is also shown to interact with Cdc47p in vivo and to be a component of high-molecular-weight MCM complexes in cell lysates. Like MCM polypeptides, Cdc45p is essential for the initiation of chromosomal DNA replication in Saccharomyces cerevisiae; however, Cdc45p remains in the nucleus throughout the cell cycle, whereas MCMs are nuclear only during G1. We characterize two mutations in CDC47 and CDC46 which arrest cells with unduplicated DNA as a result of single base substitutions. The corresponding amino acid substitutions in Cdc46p and Cdc47p severely reduce the ability of these polypeptides to assemble in a complex with each other in vivo and in vitro. This argues that assembly of Cdc47p into complexes with other MCM polypeptides is important for its role in the initiation of chromosomal DNA replication.

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KRATOCHVÍLOVÁ, IRENA, ADRIANA ZAMBOVA, JEREMIAH MBINDYO, BAHARAK RAZAVI und JOSEF HOLAKOVSKÝ. „CURRENT-VOLTAGE CHARACTERIZATION OF ALKANETHIOL SELF-ASSEMBLED MONOLAYERS IN METAL NANOWIRES“. Modern Physics Letters B 16, Nr. 05n06 (10.03.2002): 161–69. http://dx.doi.org/10.1142/s0217984902003609.

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An electric-field assisted assembly has been used to place rod-shaped, metal-organic, molecule-metal nanowires onto lithographically defined metal pads allowing the electrical characterization of metal-molecule self-assembled monolayer-metal containing nanowires. Our results show that the parameters of metal-molecule metal junctions are close to previously published data, so we have constructed systems containing insulating monolayers with reasonable properties.

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Sarnello, Erik, und Tao Li. „Synthesis and Advanced Characterization of Polymer–Protein Core–Shell Nanoparticles“. Catalysts 11, Nr. 6 (13.06.2021): 730. http://dx.doi.org/10.3390/catal11060730.

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Enzyme immobilization techniques are widely researched due to their wide range of applications. Polymer–protein core–shell nanoparticles (CSNPs) have emerged as a promising technique for enzyme/protein immobilization via a self-assembly process. Based on the desired application, different sizes and distribution of the polymer–protein CSNPs may be required. This work systematically studies the assembly process of poly(4-vinyl pyridine) and bovine serum albumin CSNPs. Average particle size was controlled by varying the concentrations of each reagent. Particle size and size distributions were monitored by dynamic light scattering, ultra-small-angle X-ray scattering, small-angle X-ray scattering and transmission electron microscopy. Results showed a wide range of CSNPs could be assembled ranging from an average radius as small as 52.3 nm, to particles above 1 µm by adjusting reagent concentrations. In situ X-ray scattering techniques monitored particle assembly as a function of time showing the initial particle growth followed by a decrease in particle size as they reach equilibrium. The results outline a general strategy that can be applied to other CSNP systems to better control particle size and distribution for various applications.

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Nanjwade, Basavaraj K. „Development of Nanocolloidosome Based Formulations and Characterization“. Nanomedicine & Nanotechnology Open Access 8, Nr. 4 (2023): 1–19. http://dx.doi.org/10.23880/nnoa-16000268.

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Microencapsulation, 30 year old field is still growing with development of new materials and active ingredient. Encapsulation is an imperative technology used to deliver the component to targeted site in an intact manner with no effect from surrounding environment. Colloidosome a novel class of microcapsule generated from the concept Pickering emulsion which is used for production of microcapsule by fixing the particle assembly at interface. Colloidosomes are hollow spherical capsule developed from controlled self-assembly of colloidal particles on emulsion droplets which reduces total interfacial energy and stabilize the structure. In this droplet act as templates for self-assembly of colloidal particles which develops stable form as per their shapes, surface properties, mass and electrical charge. Different types of emulsions are used to develop the various colloidosomes such as aqueous colloidosomes, hairy colloidosomes, nanoparticle colloidosomes, layer by layer colloidosomes and non-spherical colloidosomes. Structural characterization exhibited that the colloidosomes are most stable structure and intrinsic porosity of colloidosomes can be used for controlled and targeted drug delivery. Study of packing of particle and 3D image revealed the presence of hexagonal and pentagonal patch like soccer ball and C60 fullerenes on the surface of colloidosomes which gives stability without collapsing the structure. Increase in concentration of small particle increases attraction between the colloidosome that causes flocculation. Stability of colloidosomes affected by time required for saturation of large particle. Applications of colloidosomes are mainly useful as encapsulating agent and in controlled drug delivery. Colloidosomes are also valuable in tumor therapy, antifungal, antimicrobial therapy and in DNA delivery. The flexibility in formulation of colloidosomes will be helpful in various applications in future.

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Zhao, Binbin, Yunlong Wang, Qingchao Sun, Yuanliang Zhang, Xiao Liang und Xuewei Liu. „Monomer model: an integrated characterization method of geometrical deviations for assembly accuracy analysis“. Assembly Automation 41, Nr. 4 (26.06.2021): 514–23. http://dx.doi.org/10.1108/aa-11-2020-0165.

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Purpose Assembly accuracy is the guarantee of mechanical product performance, and the characterization of the part with geometrical deviations is the basis of assembly accuracy analysis. Design/methodology/approach The existed small displacement torsors (SDT) model cannot fully describe the part with multiple mating surfaces, which increases the difficulty of accuracy analysis. This paper proposed an integrated characterization method for accuracy analysis. By analyzing the internal coupling relationship of the different geometrical deviations in a single part, the Monomer Model was established. Findings The effectiveness of the Monomer Model is verified through an analysis of a simulated rotor assembly analysis, and the corresponding accuracy analysis method based on the model reasonably predicts the assembly deviation of the rotor. Originality/value The Monomer Model realizes the reverse calculation of assembly deformation for the first time, which can be used to identify the weak links that affect the assembly accuracy, thus support the accuracy improvement in the re-assembly stage.

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Folgado, Enrique, Matthias Mayor, Vincent Ladmiral und Mona Semsarilar. „Evaluation of Self-Assembly Pathways to Control Crystallization-Driven Self-Assembly of a Semicrystalline P(VDF-co-HFP)-b-PEG-b-P(VDF-co-HFP) Triblock Copolymer“. Molecules 25, Nr. 17 (03.09.2020): 4033. http://dx.doi.org/10.3390/molecules25174033.

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To date, amphiphilic block copolymers (BCPs) containing poly(vinylidene fluoride-co-hexafluoropropene) (P(VDF-co-HFP)) copolymers are rare. At moderate content of HFP, this fluorocopolymer remains semicrystalline and is able to crystallize. Amphiphilic BCPs, containing a P(VDF-co-HFP) segment could, thus be appealing for the preparation of self-assembled block copolymer morphologies through crystallization-driven self-assembly (CDSA) in selective solvents. Here the synthesis, characterization by 1H and 19F NMR spectroscopies, GPC, TGA, DSC, and XRD; and the self-assembly behavior of a P(VDF-co-HFP)-b-PEG-b-P(VDF-co-HFP) triblock copolymer were studied. The well-defined ABA amphiphilic fluorinated triblock copolymer was self-assembled into nano-objects by varying a series of key parameters such as the solvent and the non -solvent, the self-assembly protocols, and the temperature. A large range of morphologies such as spherical, square, rectangular, fiber-like, and platelet structures with sizes ranging from a few nanometers to micrometers was obtained depending on the self-assembly protocols and solvents systems used. The temperature-induced crystallization-driven self-assembly (TI-CDSA) protocol allowed some control over the shape and size of some of the morphologies.

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Adams, Josephine C. „Characterization of Cell–Matrix Adhesion Requirements for the Formation of Fascin Microspikes“. Molecular Biology of the Cell 8, Nr. 11 (November 1997): 2345–63. http://dx.doi.org/10.1091/mbc.8.11.2345.

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Cell adhesion to thrombospondin-1 (TSP-1) correlates with assembly of cell–substratum contact structures that contain fascin microspikes. In this analysis, cell-matrix requirements for assembly of fascin microspikes were examined in detail. In six cell lines, cell spreading on a TSP-1 substratum correlated with expression of fascin protein and formation of fascin microspikes. Microspikes were not formed by H9c2 cells adherent on fibronectin, vitronectin, collagen IV, or platelet factor 4. However, both fascin microspikes and focal contacts were assembled by cells adherent on laminin-1. Using mixed substrata containing different proportions of TSP-1, and fibronectin, fascin microspike formation by H9c2 and C2C12 cells was found to be reduced on substrata containing 25% fibronectin and abolished on substrata containing 75% fibronectin. Adhesion to intermediate mixtures of TSP-1 and fibronectin resulted in coassembly of fascin microspikes and focal contacts, colocalization of fascin with actin stress fiber bundles and altered distributions of β1 integrins, cortical α-actinin, and tropomyosin. In cells adherent on 50% TSP-1:50% fibronectin, GRGDSP peptide treatment decreased focal contact assembly and altered cytoskeletal organization but did not inhibit microspike assembly. Treatment with chondroitin sulfate A or p-nitrophenol β-d-xylopyranoside decreased microspike formation and modified cytoskeletal organization but did not inhibit focal contact formation. In polarized migratory and postmitotic C2C12 cells, fascin microspikes and ruffles were localized at leading edges and TSP matrix deposition was also concentrated in this region. Depletion of matrix TSP by heparin treatment correlated with decreased microspike formation and cell motility. Thus, the balance of adhesive receptors ligated at the cell surface during initial cell–matrix attachment serves to regulate the type of substratum adhesion contact assembled and subsequent cytoskeletal organization. A role for fascin microspikes in cell motile behavior is indicated.

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Wang, Wanneng, Zongli Hu, Jinzhe Li und Guoping Chen. „Expression characterization and actual function of the second pucBA in Rhodobacter sphaeroides“. Bioscience Reports 29, Nr. 3 (03.03.2009): 165–72. http://dx.doi.org/10.1042/bsr20080061.

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The puc2BA operon of Rhodobacter sphaeroides is highly similar to the original puc1BA operon. Genetic, biochemical and spectroscopic approaches were used to investigate the function of puc2BA; the puc1BA and puc2BA structural genes were amplified and cloned into the pRK415 vector controlled by the puc promoter from R. sphaeroides, which was then introduced into R. sphaeroides mutant strains. The results indicated that puc2BA was normally expressed and puc2BA-encoded polypeptides were assembled into membrane LHII (light-harvesting II) complexes, although the puc2A-encoded polypeptide was much larger than the puc1A-encoded polypeptide. Semi-quantitative RT-PCR (reverse transcription-PCR) and SDS/PAGE indicated that puc1BA and puc2BA were expressed in R. sphaeroides when integrated into the genome or expressed from vectors. Furthermore, the polypeptides from the puc1BA and puc2BA genes were both involved in LHII assembly, and pucC is also necessary to assemble LHII complexes. Nevertheless, the LHII complexes synthesized from puc2BA in R. sphaeroides have blue-shift absorption bands at 801 and 846 nm.

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Liu, Jian She, Yan Fei Zhang, Mei Mei Geng, Jia Zeng und Guan Zhou Qiu. „Research on isc Operon in Acidithiobacillus ferrooxidans ATCC 23270“. Advanced Materials Research 20-21 (Juli 2007): 509–12. http://dx.doi.org/10.4028/www.scientific.net/amr.20-21.509.

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The highly conserved operon iron–sulfur cluster (iscSUA) is essential for the general biogenesis and transfer of iron–sulfur proteins in bacteria. In this study, expression, purification and characterization of the proteins of the isc operon (iscSUA) of Acidithiobacillus ferrooxidans ATCC 23270 was studied. Assembly and transfer of [Fe4S4] in vitro during the isc proteins and other iron sulfur proteins was studied in order to detect the pathway and mechanism of [Fe4S4] assembly and transfer in vivo. The [Fe4S4] cluster was successfully assembled in iron-sulfur proteins in vitro in the presence of Fe2+ and sulfide, and it was successfully transferred from IscA or IscU to iron- sulfur proteins. Our results support and extend certain models of iron-sulfur clusters assembly and transfer.

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Bailly, Nathalie, Gwenaelle Pound-Lana und Bert Klumperman. „Synthesis, Characterization, and Self-Assembly of Poly(N-vinylpyrrolidone)-block-poly(vinyl acetate)“. Australian Journal of Chemistry 65, Nr. 8 (2012): 1124. http://dx.doi.org/10.1071/ch12185.

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Poly(N-vinylpyrrolidone)-block-poly(vinyl acetate) (PVP-b-PVAc) block copolymers of varying molar mass and hydrophobic block lengths were synthesized by xanthate-mediated radical polymerization. In order to control the molar mass of the hydrophilic PVP block, a xanthate chain transfer agent, S-(2-cyano-2-propyl) O-ethyl xanthate, was used. The PVP-b-PVAc block copolymer is composed of a hydrophilic and hydrophobic segment, and has the ability to self-assemble in aqueous solution. The PVP-b-PVAc block copolymers were characterized by 1H NMR spectroscopy to confirm their self-assembly in water. The critical micelle concentration was determined by fluorescence spectroscopy. A combination of dynamic light scattering, transmission electron microscopy, and static light scattering was used to further characterize the self-assembly of the block copolymers in water.

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Simon, Gerold, und Marina Sokcic-Kostic. „Famos III, burn-up measurement system suitable for la Hague acceptance criteria control“. Nuclear Technology and Radiation Protection 17, Nr. 1-2 (2002): 68–70. http://dx.doi.org/10.2298/ntrp0202068s.

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Fuel Assembly Monitoring System (FAMOS) was developed to set up a NDA method for the characterization of light water reactor fuel assemblies. The applied active/passive monitoring system made total characterization of fuel assemblies possible, without any previous knowledge of fuel assembly data or reactor operating data. FAMOS III measurement system was especially developed for the determination of fuel assembly burn-up which is suitable for the control of the acceptance criteria in the so-called La Hague measurements.

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Croitoriu, Alexandra, Loredana Elena Nita, Alina Gabriela Rusu, Alina Ghilan, Maria Bercea und Aurica P. Chiriac. „New Fmoc-Amino Acids/Peptides-Based Supramolecular Gels Obtained through Co-Assembly Process: Preparation and Characterization“. Polymers 14, Nr. 16 (17.08.2022): 3354. http://dx.doi.org/10.3390/polym14163354.

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One of the methods of obtaining supramolecular gels consists of the possibility of self-assembly of low molecular weight gelators (LMWGs). However, LMWG-based gels are often difficult to handle, easy to destroy and have poor rheological performance. In order to improve the gels’ properties, the LMWGs molecules are co-assembled, which induces more cross-links with more stable structures. Starting from these aspects, the present study refers to the preparation of a bionic hydrogel stabilized with a physiologically occurring, bifunctional biomolecule, L-lysine, co-assembled with other amino acids or peptides (such as a modified amino acid (Fmoc-serine or Fmoc-glutamic acid) or a tripeptide (Fmoc-Gly-Gly-Gly)) with the potential to support the repair of injuries or the age-related impaired structures or functions of living tissues. The introduction of a copartner aims to improve hydrogel characteristics from a morphological, rheological and structural point of view. On the other hand, the process will allow the understanding of the phenomenon of specific self-association and molecular recognition. Various characterization techniques were used to assess the ability to co-assemble: DLS, FT-IR, SEM and fluorescence microscopy, rheology and thermal analysis. Studies have confirmed that the supramolecular structure occurs through the formation of inter- and intramolecular physical bonds that ensure the formation of fibrils organized into 3D networks. The rheological data, namely the G′ > G″ and tan δ approximately 0.1–0.2 gel-like behavior observed for all studied samples, demonstrate and sustain the appearance of the co-assembly processes and the ability of the samples to act as LMWG. From the studied systems, the Fmoc–Lys–Fmoc_ Fmoc–Glu sample presented the best rheological characteristics that are consistent with the observations that resulted from the dichroism, fluorescence and SEM investigations.

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Strasser, Stefan, Albert Zink, Wolfgang M. Heckl und Stefan Thalhammer. „Controlled Self-Assembly of Collagen Fibrils by an Automated Dialysis System“. Journal of Biomechanical Engineering 128, Nr. 5 (12.03.2006): 792–96. http://dx.doi.org/10.1115/1.2264392.

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In vitro self-assembled collagen fibrils form a variety of different structures during dialysis. The self-assembly is dependent on several parameters, such as concentrations of collagen and α1-acid glycoprotein, temperature, dialysis time, and the acid concentration. For a detailed understanding of the assembly pathway and structural features like banding pattern or mechanical properties it is necessary to study single collagen fibrils. In this work we present a fully automated system to control the permeation of molecules through a membrane like a dialysis tubing. This allows us to ramp arbitrary diffusion rate profiles during the self-assembly process of macromolecules, such as collagen. The system combines a molecular sieving method with a computer assisted control system for measuring process variables. With the regulation of the diffusion rate it is possible to control and manipulate the collagen self-assembly process during the whole process time. Its performance is demonstrated by the preparation of various collagen type I fibrils and native collagen type II fibrils. The combination with the atomic force microscope (AFM) allows a high resolution characterization of the self-assembled fibrils. In principle, the represented system can be also applied for the production of other biomolecules, where a dialysis enhanced self-assembly process is used.

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Gaspar, Andrew H., und Hung Ton-That. „Assembly of Distinct Pilus Structures on the Surface of Corynebacterium diphtheriae“. Journal of Bacteriology 188, Nr. 4 (15.02.2006): 1526–33. http://dx.doi.org/10.1128/jb.188.4.1526-1533.2006.

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ABSTRACT Different surface organelles contribute to specific interactions of a pathogen with host tissues or infectious partners. Multiple pilus gene clusters potentially encoding different surface structures have been identified in several gram-positive bacterial genomes sequenced to date, including actinomycetales, clostridia, corynebacteria, and streptococci. Corynebacterium diphtheriae has been shown to assemble a pilus structure, with sortase SrtA essential for the assembly of a major subunit SpaA and two minor proteins, SpaB and SpaC. We report here the characterization of a second pilus consisting of SpaD, SpaE, and SpaF, of which SpaD and SpaE form the pilus shaft and SpaF may be located at the pilus tip. The structure of the SpaDEF pilus contains no SpaABC pilins as detected by immunoelectron microscopy. Neither deletion of spaA nor sortase srtA abolishes SpaDEF pilus formation. The assembly of the SpaDEF pilus requires specific sortases located within the SpaDEF pilus gene cluster. Although either sortase SrtB or SrtC is sufficient to polymerize SpaDF, the incorporation of SpaE into the SpaD pili requires sortase SrtB. In addition, an alanine in place of the lysine of the SpaD pilin motif abrogates pilus polymerization. Thus, SpaD, SpaE, and SpaF constitute a different pilus structure that is independently assembled and morphologically distinct from the SpaABC pili and possibly other pili of C. diphtheriae.

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KIM, TAE-HO, und O. OK PARK. „FABRICATION AND CHARACTERIZATION OF SPIN SELF-ASSEMBLED PPV/MONTMORILLONITE MULTILAYER THIN FILMS“. Journal of Nonlinear Optical Physics & Materials 13, Nr. 03n04 (Dezember 2004): 581–86. http://dx.doi.org/10.1142/s0218863504002298.

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Multilayer nanostructural thin films through a layer-by-layer spin self-assembly method were prepared using poly(p-phenylene vinylene)/montmorillonite. Sodium montmorillonite particles exfoliated into single sheets and cationic PPV precursor and such anionic MMT plates were spin self-assembled by electrostatic attraction. Self-assembled MMT layers blocked the penetration of oxygen and moisture and they reduced the photo-oxidation of the emitting material. Spin self-assembled films showed higher environmental stability and luminescence, and their PL spectra were somewhat different from that of bulk PPV films.

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Hur, Yoon Hyung, Seung Won Song, Jimmy Mays, YongJoo Kim, Beom-Goo Kang und Yeon Sik Jung. „Synthesis of poly(styrene-b-4-(tert-butyldimethylsiloxy)styrene) block copolymers and characterization of their self-assembled patterns“. Molecular Systems Design & Engineering 2, Nr. 5 (2017): 589–96. http://dx.doi.org/10.1039/c7me00085e.

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Burns, R. G. „Assembly of chick brain MAP2-tubulin microtubule protein. Characterization of the protein and the MAP2-dependent addition of tubulin dimers“. Biochemical Journal 277, Nr. 1 (01.07.1991): 231–38. http://dx.doi.org/10.1042/bj2770231.

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The principle proteins present in twice-cycled chick brain microtubule protein were characterized. The protein consists of a stoichiometric mixture of MAP2 and tubulin, together with a number of minor components. Its composition remains unaltered after a third cycle of assembly in a buffer supplemented with 67 mM-NaCl, with the exception of the phosphorylation of MAP2 to a low level (congruent to 1 mol.mol-1). The inclusion of 67 mM-NaCl dissociates the MAP2-tubulin oligomers, and restricts the assembly to the MAP2-dependent addition and loss of tubulin dimers, such that the assembly kinetics approximate to a simple pseudo-first-order reaction. The assembled microtubules exhibit dynamic instability, with no evidence for end-to-end annealing.

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Huang, Yuan Ming. „Self-Assembled Optical Gratings with Banana-Shaped Liquid Crystals“. Key Engineering Materials 428-429 (Januar 2010): 12–23. http://dx.doi.org/10.4028/www.scientific.net/kem.428-429.12.

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We demonstrated that a homologous series of banana-shaped liquid crystals, 1,3-phenylene bis(4-alkyloxybenzylideneamine), could assemble themselves into various kinds of groove-free diffraction gratings when their isotropic melts were slowly cooled into mesophases between two pieces of glass substrates. The groove-free diffraction gratings included one-dimensional parallel gratings, two-dimensional crossed gratings, two-dimensional fan-shaped gratings and two-dimensional circular gratings. Characterization by means of polarized optical microscopy showed that a pattern of periodic modulation of the refractive index was developed in the thin films formed by the banana-shaped compound. Our laser light diffraction experiments confirmed that these groove-free gratings could effectively diffract the incident red light from a helium-neon laser. On the basis of the diffraction equations derived for the self-assembled groove-free optical gratings, the diffraction patterns were simulated for the parallel gratings, orthogonally crossed gratings, fan-shaped gratings and circular gratings, respectively, and good agreement was achieved. The mechanisms on the self-assembly of the banana-shaped molecules were discussed in terms of intermolecular interactions. Our work provides an alternative method for manufacturing diffraction gratings by harnessing the self-assembly of banana-shaped molecules.

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Subrahmanyam, Vishnu B., und Dwayne R. Speer. „Deep-Bed Fiberglass Filter Assembly Radiological Characterization“. Nuclear Technology 86, Nr. 2 (August 1989): 207–13. http://dx.doi.org/10.13182/nt89-a34272.

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Cheng, Bowen, Dirk De Bruyker, Chris Chua, Kunal Sahasrabuddhe, Ivan Shubin, John E. Cunningham, Ying Luo, Karl F. Bohringer, Ashok V. Krishnamoorthy und Eugene M. Chow. „Microspring Characterization and Flip-Chip Assembly Reliability“. IEEE Transactions on Components, Packaging and Manufacturing Technology 3, Nr. 2 (Februar 2013): 187–96. http://dx.doi.org/10.1109/tcpmt.2012.2213250.

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Chen, Sihai, Zhiyong Fan und David L. Carroll. „Silver Nanodisks: Synthesis, Characterization, and Self-Assembly“. Journal of Physical Chemistry B 106, Nr. 42 (Oktober 2002): 10777–81. http://dx.doi.org/10.1021/jp026376b.

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Mohapatra, Himansu Shekhar, Arobindo Chatterjee und Pramod Kumar. „Characterization of Fibrous Assembly from Lime Peel Extract“. International Journal of Pharmacology, Phytochemistry and Ethnomedicine 1 (Dezember 2015): 27–36. http://dx.doi.org/10.18052/www.scipress.com/ijppe.1.27.

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The present research focuses on the development of anti-oxidant and antimicrobial polymeric fibrous material based on lime peel extract which contains many bioactive compounds having medicinal and healthcare properties. The aim of the present research is to generate fibrous assembly from lime peel extract and characterize the newly developed fibrous assembly in terms of chemical group identification, burning behavior, solubility behavior, thermal behavior, moisture absorbency and microscopic behavior. The antibacterial activity is also studied for possible application in the suitable area of medical textiles. The fibrous assembly primarily composed of about lignin, cellulose, hemicelluloses and different polyphenolic compounds such as flavonoid, shows excellent moisture absorbency and antimicrobial property against E. coli and S. aureus strains. The fibrous assembly has potential for applications in the wound dressing and healthcare sector.

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Matarranz, Beatriz, Angel Sampedro, Constantin G. Daniliuc und Gustavo Fernández. „Self-Assembly of a Carboxyl-Functionalized BODIPY Dye via Hydrogen Bonding“. Crystals 8, Nr. 11 (20.11.2018): 436. http://dx.doi.org/10.3390/cryst8110436.

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We report the synthesis, characterization, and self-assembly behavior of a 4,4-Difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) dye functionalized at the meso-position with a butyric acid group. Various spectroscopic investigations (UV-Vis, emission, and Fourier-transform infrared spectroscopy (FTIR) studies) supported by X-ray analysis revealed the formation of self-assembled structures in the solid state with translationally stacked BODIPY units driven by hydrogen bonding between the carboxyl groups.

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Kutrovskaya, Stella, Vlad Samyshkin, Anastasia Lelekova, Alexey Povolotskiy, Anton Osipov, Sergey Arakelian, Alexey Vitalievich Kavokin und Alexey Kucherik. „Field-Induced Assembly of sp-sp2 Carbon Sponges“. Nanomaterials 11, Nr. 3 (17.03.2021): 763. http://dx.doi.org/10.3390/nano11030763.

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The formation of macroscale carbon structures characterised by an sp-sp2-hybridization is realised by self-assembly in colloidal solutions under an effect of laser irradiation and electromagnetic fields. The sponge-like morphology, sculptured with gold nanoparticles (NPs) was revealed by Scanning Electron Microscopy (SEM) imaging. Full structural and defect characterization of the self-assembled sponges was provided using the micro-Raman spectroscopic technique. The synthesized clusters manifest themselves in the presence of a strong spectral band in the visible range of the photoluminescence spectra that is quite unusual for ordered sp2-carbon systems.

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Costagli, Simone, Linda Abenaim, Giulia Rosini, Barbara Conti und Roberto Giovannoni. „De Novo Genome Assembly at Chromosome-Scale of Hermetia illucens (Diptera Stratiomyidae) via PacBio and Omni-C Proximity Ligation Technology“. Insects 15, Nr. 2 (17.02.2024): 133. http://dx.doi.org/10.3390/insects15020133.

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Hermetia illucens is a species of great interest for numerous industrial applications. A high-quality reference genome is already available for H. illucens. However, the worldwide maintenance of numerous captive populations of H. illucens, each with its own genotypic and phenotypic characteristics, made it of interest to perform a de novo genome assembly on one population of H. illucens to define a chromosome-scale genome assembly. By combining the PacBio and the Omni-C proximity ligation technologies, a new H. illucens chromosome-scale genome of 888.59 Mb, with a scaffold N50 value of 162.19 Mb, was assembled. The final chromosome-scale assembly obtained a BUSCO completeness of 89.1%. By exploiting the Omni-C proximity ligation technology, topologically associated domains and other topological features that play a key role in the regulation of gene expression were identified. Further, 65.62% of genomic sequences were masked as repeated sequences, and 32,516 genes were annotated using the MAKER pipeline. The H. illucens Lsp-2 genes that were annotated were further characterized, and the three-dimensional organization of the encoded proteins was predicted. A new chromosome-scale genome assembly of good quality for H. illucens was assembled, and the genomic annotation phase was initiated. The availability of this new chromosome-scale genome assembly enables the further characterization, both genotypically and phenotypically, of a species of interest for several biotechnological applications.

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Gordon, Emile B., Christopher J. Knuff und Bentley A. Fane. „Conformational Switch-Defective ϕX174 Internal Scaffolding Proteins Kinetically Trap Assembly Intermediates before Procapsid Formation“. Journal of Virology 86, Nr. 18 (03.07.2012): 9911–18. http://dx.doi.org/10.1128/jvi.01120-12.

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Conformational switching is an overarching paradigm in which to describe scaffolding protein-mediated virus assembly. However, rapid morphogenesis with small assembly subunits hinders the isolation of early morphogenetic intermediates in most model systems. Consequently, conformational switches are often defined by comparing the structures of virions, procapsids and aberrantly assembled particles. In contrast, ϕX174 morphogenesis proceeds through at least three preprocapsid intermediates, which can be biochemically isolated. This affords a detailed analysis of early morphogenesis and internal scaffolding protein function. Amino acid substitutions were generated for the six C-terminal, aromatic amino acids that mediate most coat-internal scaffolding protein contacts. The biochemical characterization of mutant assembly pathways revealed two classes of molecular defects, protein binding and conformational switching, a novel phenotype. The conformational switch mutations kinetically trapped assembly intermediates before procapsid formation. Although mutations trapped different particles, they shared common second-site suppressors located in the viral coat protein. This suggests a fluid assembly pathway, one in which the scaffolding protein induces a single, coat protein conformational switch and not a series of sequential reactions. In this model, an incomplete or improper switch would kinetically trap intermediates.

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Sandefur, Stephanie, Rita M. Smith, Vasundhara Varthakavi und Paul Spearman. „Mapping and Characterization of the N-Terminal I Domain of Human Immunodeficiency Virus Type 1 Pr55Gag“. Journal of Virology 74, Nr. 16 (15.08.2000): 7238–49. http://dx.doi.org/10.1128/jvi.74.16.7238-7249.2000.

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ABSTRACT Human immunodeficiency virus (HIV) type 1 particles assemble at the plasma membrane of cells in a manner similar to that of the type C oncoretroviruses. The Pr55Gag molecule directs the assembly process and is sufficient for particle assembly in the absence of all other viral gene products. The I domain is an assembly domain that has been previously localized to the nucleocapsid (NC) region of Gag. In this study we utilized a series of Gag-green fluorescent protein (GFP) fusion proteins to precisely identify sequences that constitute the N-terminal I domain of Pr55Gag. The minimal sequence required for the I domain was localized to the extreme N terminus of NC. Two basic residues (arginine 380 and arginine 384) within the initial seven residues of NC were found to be critical for the function of the N-terminal I domain. The presence of positive charge alone in these two positions, however, was not sufficient to mediate the formation of dense Gag particles. The I domain was required for the formation of detergent-resistant complexes of Gag protein, and confocal microscopy demonstrated that the I domain was also required for the formation of punctate foci of Gag proteins at the plasma membrane. Electron microscopic analysis of cells expressing Gag-GFP fusion constructs with an intact I domain revealed numerous retrovirus-like particles (RVLPs) budding from the plasma membrane, while I domain-deficient constructs failed to generate visible RVLPs. These results provide evidence that Gag-Gag interactions mediated by the I domain play a central role in the assembly of HIV particles.

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Schulze, Benjamin M., Davita L. Watkins, Jing Zhang, Ion Ghiviriga und Ronald K. Castellano. „Estimating the shape and size of supramolecular assemblies by variable temperature diffusion ordered spectroscopy“. Org. Biomol. Chem. 12, Nr. 40 (2014): 7932–36. http://dx.doi.org/10.1039/c4ob01373e.

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Reported is characterization of the self-assembly of π-conjugated oligomers, molecules studied recently in photovoltaic devices, using variable temperature diffusion ordered spectroscopy; the approach has allowed estimation of assembly size, shape, and molecularity.

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Bormashenko, Edward, Mark Frenkel, Alla Vilk, Irina Legchenkova, Alexander Fedorets, Nurken Aktaev, Leonid Dombrovsky und Michael Nosonovsky. „Characterization of Self-Assembled 2D Patterns with Voronoi Entropy“. Entropy 20, Nr. 12 (11.12.2018): 956. http://dx.doi.org/10.3390/e20120956.

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The Voronoi entropy is a mathematical tool for quantitative characterization of the orderliness of points distributed on a surface. The tool is useful to study various surface self-assembly processes. We provide the historical background, from Kepler and Descartes to our days, and discuss topological properties of the Voronoi tessellation, upon which the entropy concept is based, and its scaling properties, known as the Lewis and Aboav–Weaire laws. The Voronoi entropy has been successfully applied to recently discovered self-assembled structures, such as patterned microporous polymer surfaces obtained by the breath figure method and levitating ordered water microdroplet clusters.

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Roberts, Douglas G. W., Mary Rose Lamb und Carol L. Dieckmann. „Characterization of the EYE2 Gene Required for Eyespot Assembly in Chlamydomonas reinhardtii“. Genetics 158, Nr. 3 (01.07.2001): 1037–49. http://dx.doi.org/10.1093/genetics/158.3.1037.

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Abstract The unicellular biflagellate green alga Chlamydomonas reinhardtii can perceive light and respond by altering its swimming behavior. The eyespot is a specialized structure for sensing light, which is assembled de novo at every cell division from components located in two different cellular compartments. Photoreceptors and associated signal transduction components are localized in a discrete patch of the plasma membrane. This patch is tightly packed against an underlying sandwich of chloroplast membranes and carotenoid-filled lipid granules, which aids the cell in distinguishing light direction. In a prior screen for mutant strains with eyespot defects, the EYE2 locus was defined by the single eye2-1 allele. The mutant strain has no eyespot by light microscopy and has no organized carotenoid granule layers as judged by electron microscopy. Here we demonstrate that the eye2-1 mutant is capable of responding to light, although the strain is far less sensitive than wild type to low light intensities and orients imprecisely. Therefore, pigment granule layer assembly in the chloroplast is not required for photoreceptor localization in the plasma membrane. A plasmid-insertion mutagenesis screen yielded the eye2-2 allele, which allowed the isolation and characterization of the EYE2 gene. The EYE2 protein is a member of the thioredoxin superfamily. Site-directed mutagenesis of the active site cysteines demonstrated that EYE2 function in eyespot assembly is redox independent, similar to the auxiliary functions of other thioredoxin family members in protein folding and complex assembly.

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Ren, Guolian, Pei Chen, Jiaqi Tang, Wenju Guo, Rongrong Wang, Ning Li, Yujie Li, Guoshun Zhang, Ruili Wang und Shuqiu Zhang. „In vivo and in vitro evaluation of dihydroartemisinin prodrug nanocomplexes as a nano-drug delivery system: characterization, pharmacokinetics and pharmacodynamics“. RSC Advances 10, Nr. 29 (2020): 17270–79. http://dx.doi.org/10.1039/d0ra02150d.

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To develop new, more effective and lower toxicity antitumor dihydroartemisinin (DHA) nanocomplexes, a DHA prodrug synthesized in this study was used to prepare DHA prodrug self-assembled nanocomplexes (DHANPs) by molecular self-assembly technology.

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Hernández, Laura P., Almudena González-Álvarez, Ana I. Oliva und Pablo Ballester. „Metal-mediated multiporphyrin functional assemblies“. Journal of Porphyrins and Phthalocyanines 13, Nr. 04n05 (April 2009): 481–93. http://dx.doi.org/10.1142/s1088424609000693.

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During the last ten years, our research group has been applying metal-mediated self-assembly processes to the construction of multiporphyrin functional assemblies. The construction of well-defined and discrete supramolecular structures resulting from self-assembly requires the use of multiple and separated connections operating in one or more closed loops. Consequently, the great majority of the multiporphyrin assemblies that we have prepared are of cyclic nature. We have placed special emphasis not only on the characterization in solution of the formed assemblies but also on the thermodynamic characterization of the assembly process and in the assessment of cooperativity. Finally, we also present examples in which functionality has been derived from the three-dimensional structures of multicomponent assemblies.

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Du, Xuewen, Jie Zhou, Xinming Li und Bing Xu. „Self-assembly of nucleopeptides to interact with DNAs“. Interface Focus 7, Nr. 6 (20.10.2017): 20160116. http://dx.doi.org/10.1098/rsfs.2016.0116.

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As a novel class of biomaterials, nucleopeptides, via the conjugation of nucleobases and peptides, usually self-assemble to form nanofibres driven mainly by hydrogen bonds. Containing nucleobase(s), nucleopeptides have a unique property—interacting with nucleic acids. Here we report the design and characterization of nucleopeptides that self-assemble in water and are able to interact with single-stranded DNAs (ssDNAs). Containing nucleobases on their side chains, these nucleopeptides bind with the ssDNAs, and the ssDNAs reciprocally affect the self-assembly of nucleopeptides. In addition, the interactions between nucleopeptides and ssDNAs also decrease their proteolytic resistance against proteinase K, which further demonstrates the binding with ssDNAs. The nucleopeptides also interact with plasmid DNA and deliver hairpin DNA into cells. This work illustrates a new and rational approach to create soft biomaterials by the integration of nucleobases and peptides to bind with DNA, which may lead to the development of nucleopeptides for controlling DNA in cells.

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McPherson, D. C., H. Kim, M. Hahn, R. Wang, P. Grabowski, P. Eichenberger und A. Driks. „Characterization of the Bacillus subtilis Spore Morphogenetic Coat Protein CotO“. Journal of Bacteriology 187, Nr. 24 (15.12.2005): 8278–90. http://dx.doi.org/10.1128/jb.187.24.8278-8290.2005.

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ABSTRACT Bacillus spores are protected by a structurally and biochemically complex protein shell composed of over 50 polypeptide species, called the coat. Coat assembly in Bacillus subtilis serves as a relatively tractable model for the study of the formation of more complex macromolecular structures and organelles. It is also a critical model for the discovery of strategies to decontaminate B. anthracis spores. In B. subtilis, a subset of coat proteins is known to have important roles in assembly. Here we show that the recently identified B. subtilis coat protein CotO (YjbX) has an especially important morphogenetic role. We used electron and atomic force microscopy to show that CotO controls assembly of the coat layers and coat surface topography as well as biochemical and cell-biological analyses to identify coat proteins whose assembly is CotO dependent. cotO spores are defective in germination and partially sensitive to lysozyme. As a whole, these phenotypes resemble those resulting from a mutation in the coat protein gene cotH. Nonetheless, the roles of CotH and CotO and the proteins whose assembly they direct are not identical. Based on fluorescence and electron microscopy, we suggest that CotO resides in the outer coat (although not on the coat surface). We propose that CotO and CotH participate in a late phase of coat assembly. We further speculate that an important role of these proteins is ensuring that polymerization of the outer coat layers occurs in such a manner that contiguous shells, and not unproductive aggregates, are formed.

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Liu, W. L., K. Alim, A. A. Balandin, D. M. Mathews und J. A. Dodds. „Assembly and characterization of hybrid virus-inorganic nanotubes“. Applied Physics Letters 86, Nr. 25 (20.06.2005): 253108. http://dx.doi.org/10.1063/1.1952587.

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Mantooth, B. A., und P. S. Weiss. „Fabrication, assembly, and characterization of molecular electronic components“. Proceedings of the IEEE 9, Nr. 11 (November 2003): 1785–802. http://dx.doi.org/10.1109/jproc.2003.818320.

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Liu, Bin, Stéphanie Baudrey, Luc Jaeger und Guillermo C. Bazan. „Characterization of TectoRNA Assembly with Cationic Conjugated Polymers“. Journal of the American Chemical Society 126, Nr. 13 (April 2004): 4076–77. http://dx.doi.org/10.1021/ja031552v.

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