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Single particle electron microscopy

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https://www.readbyqxmd.com/read/28094243/linear-and-ultrafast-nonlinear-plasmonics-of-single-nano-objects
#1
Aurelien Crut, Paolo Maioli, Fabrice Vallee, Natalia Del Fatti
Single-particle optical investigations have greatly improved our understanding of the fundamental properties of nano-objects, avoiding the spurious inhomogeneous effects that affect ensemble experiments. Correlation with high-resolution imaging techniques providing morphological information (e.g., electron microscopy) allows a quantitative interpretation of the optical measurements by means of analytical models and numerical simulations. In this topical review, we first briefly recall the principles underlying some of the most commonly used single-particle optical techniques: near-field, dark-field, spatial modulation and photothermal microscopies/spectroscopies...
January 17, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
https://www.readbyqxmd.com/read/28091597/direct-visualization-of-hydrogen-absorption-dynamics-in-individual-palladium-nanoparticles
#2
Tarun C Narayan, Fariah Hayee, Andrea Baldi, Ai Leen Koh, Robert Sinclair, Jennifer A Dionne
Many energy storage materials undergo large volume changes during charging and discharging. The resulting stresses often lead to defect formation in the bulk, but less so in nanosized systems. Here, we capture in real time the mechanism of one such transformation-the hydrogenation of single-crystalline palladium nanocubes from 15 to 80 nm-to better understand the reason for this durability. First, using environmental scanning transmission electron microscopy, we monitor the hydrogen absorption process in real time with 3 nm resolution...
January 16, 2017: Nature Communications
https://www.readbyqxmd.com/read/28089911/atypical-composition-and-structure-of-the-mitochondrial-dimeric-atp-synthase-from-euglena-gracilis
#3
K N Sathish Yadav, Héctor V Miranda-Astudillo, Lilia Colina-Tenorio, Fabrice Bouillenne, Hervé Degand, Pierre Morsomme, Diego González-Halphen, Egbert J Boekema, Pierre Cardol
Mitochondrial respiratory-chain complexes from Euglenozoa comprise classical subunits described in other eukaryotes (i.e. mammals and fungi) and subunits that are restricted to Euglenozoa (e.g. Euglena gracilis and Trypanosoma brucei). Here we studied the mitochondrial F1FO-ATP synthase (or Complex V) from the photosynthetic eukaryote E. gracilis in detail. The enzyme was purified by a two-step chromatographic procedure and its subunit composition was resolved by a three-dimensional gel electrophoresis (BN/SDS/SDS)...
January 12, 2017: Biochimica et Biophysica Acta
https://www.readbyqxmd.com/read/28089412/whaddaya-know-a-guide-to-uncertainty-and-subjectivity-in-structural-biology
#4
REVIEW
Joel P Mackay, Michael J Landsberg, Andrew E Whitten, Charles S Bond
The methods of structural biology, while powerful, are technically complex. Although the Protein Data Bank (PDB) provides a repository that allows anyone to download any structure, many users would not appreciate the caveats that should be considered when examining a structure. Here, we describe several key uncertainties associated with the application of X-ray crystallography, NMR spectroscopy, single-particle electron microscopy (SPEM), and small-angle scattering (SAS) to biological macromolecules. The take-home message is that structures are not absolute truths - they are models that fit the experimental data and therefore have uncertainty and subjectivity associated with them...
January 11, 2017: Trends in Biochemical Sciences
https://www.readbyqxmd.com/read/28088362/molecular-characterization-of-a-novel-orthomyxovirus-from-rainbow-and-steelhead-trout-oncorhynchus-mykiss
#5
William N Batts, Scott E LaPatra, Ryan Katona, Eric Leis, Terry Fei Fan Ng, Marine S O Brieuc, Rachel B Breyta, Maureen K Purcell, Carla M Conway, Thomas B Waltzek, Eric Delwart, James R Winton
A novel virus, rainbow trout orthomyxovirus (RbtOV), was isolated in 1997 and again in 2000 from commercially-reared rainbow trout (Oncorhynchus mykiss) in Idaho, USA. The virus grew optimally in the CHSE-214 cell line at 15°C producing a diffuse cytopathic effect; however, juvenile rainbow trout exposed to cell culture-grown virus showed no mortality or gross pathology. Electron microscopy of preparations from infected cell cultures revealed the presence of typical orthomyxovirus particles. The complete genome of RbtOV is comprised of eight linear segments of single-stranded, negative-sense RNA having highly conserved 5' and 3'-terminal nucleotide sequences...
January 11, 2017: Virus Research
https://www.readbyqxmd.com/read/28070848/intravaginal-delivery-of-polyphenon-60-and-curcumin-nanoemulsion-gel
#6
Atinderpal Kaur, Yashaswee Saxena, Rakhi Bansal, Sonal Gupta, Amit Tyagi, Rakesh Kumar Sharma, Javed Ali, Amulya Kumar Panda, Reema Gabrani, Shweta Dang
Polyphenon 60 (P60) and curcumin (CUR) were loaded in a single nanoemulsion system and their combined antibacterial action was studied against uropathogenic Escherichia coli. To enhance availability at target organs and to inhibit enzymatic degradation in gastro intestinal tract, vaginal route of administration was explored. P60 + CUR nanoemulsion (NE) was formulated by ultra-sonication and optimized using Box-Behnken design. Optimized NE showed Z-average of 211.2 nm, polydispersity index of 0.343, and zeta potential of -32...
January 9, 2017: AAPS PharmSciTech
https://www.readbyqxmd.com/read/28067378/hot-electron-driven-hydrogen-evolution-using-anisotropic-gold-nanostructure-assembled-monolayer-mos2
#7
Peng Zhang, Mamoru Fujitsuka, Tetsuro Majima
Plasmonic nanostructures attracting particular interest in plasmon-induced highly energetic electrons, also known as hot electrons, play a fundamental role in photocatalysis for solar energy conversion. Plasmon-induced hot electron excitation, relaxation, transport, and injection to two-dimensional semiconductors are necessary to clearly understand the efficient plasmon-induced chemical reaction. Herein, we use a plasmonic photocatalyst composed of anisotropic gold nanostructures as the electron donor assembled on two-dimensional molybdenum dichalcogenide, monolayer MoS2, as the electron acceptor in order to unveil the plasmon-induced interfacial hot electron transfer for the hydrogen evolution reaction (HER)...
January 9, 2017: Nanoscale
https://www.readbyqxmd.com/read/28065477/quantitative-analysis-of-the-yield-of-avian-h7-influenza-virus-haemagglutinin-protein-produced-in-silkworm-pupae-with-the-use-of-the-codon-optimized-dna-a-possible-oral-vaccine
#8
Kuniaki Nerome, Sayaka Matsuda, Kenichi Maegawa, Shigeo Sugita, Kazumichi Kuroda, Kazunori Kawasaki, Reiko Nerome
In this study, we aimed to quantitatively compare the increased production of three H7 influenza virus-like particle (VLP) haemagglutinin (HA) with the use of a codon-optimized single HA gene in silkworm pupae. Recombinant baculovirus (Korea H7-BmNPV) could produce 0.40 million HA units per pupa, corresponding to 1832μg protein. The yield of the HA produced in larva was estimated to be approximately 0.31 million HA units per larva, and there were no significant differences between the three HA proteins. We could establish efficient recovery system of HA production in larvae and pupae with the use of three cycles sonication methods...
January 5, 2017: Vaccine
https://www.readbyqxmd.com/read/28064392/chemical-composition-structural-properties-and-source-apportionment-of-organic-macromolecules-in-atmospheric-pm10-in-a-coastal-city-of-southeast-china
#9
Yanting Chen, Wenjiao Du, Jinsheng Chen, Youwei Hong, Jinping Zhao, Lingling Xu, Hang Xiao
Particulate matter (PM10) associated with the fractions of organic macromolecules, including humic acid (HA), kerogen + black carbon (KB), and black carbon (BC), was determined during summer and winter at urban and suburban sites in a coastal city of southeast China. The organic macromolecules were characterized by elemental analysis (EA), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR), and their sources were identified by using stable carbon/nitrogen isotope (δ(13)C/δ(15)N) and the Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) Model...
January 7, 2017: Environmental Science and Pollution Research International
https://www.readbyqxmd.com/read/28057460/a-characterization-of-structural-proteins-expressed-by-bombyx-mori-bidensovirus
#10
Peng Lü, Yali Xing, Zhaoyang Hu, Yanhua Yang, Ye Pan, Kangmin Chen, Feifei Zhu, Yajing Zhou, Keping Chen, Qin Yao
Bombyx mori bidensiovirus (BmBDV) is a species of Bidensovirus that has been was placed into a new genus within the new family Bidnaviridae by the International Committee on Taxonomy of Viruses. BmBDV causes fatal flacherie disease in silkworms, which causes large losses to the sericulture industry. BmBDV contains two sets of complementary linear single-stranded DNAs of approximately 6.5 kb (viral DNA 1, VD1) and 6.0 kb (viral DNA 2, VD2). VD1 and VD2 are encapsidated in separate icosahedral non-enveloped capsids, which are similar in size and shape...
January 2, 2017: Journal of Invertebrate Pathology
https://www.readbyqxmd.com/read/28055037/advances-in-the-field-of-single-particle-cryo-electron-microscopy-over-the-last-decade
#11
Joachim Frank
In single-particle cryo-electron microscopy (cryo-EM), molecules suspended in a thin aqueous layer are rapidly frozen and imaged at cryogenic temperature in the transmission electron microscope. From the random projection views, a three-dimensional image is reconstructed, enabling the structure of the molecule to be obtained. In this article I discuss technological progress over the past decade, which has, in my own field of study, culminated in the determination of ribosome structure at 2.5-Å resolution. I also discuss likely future improvements in methodology...
February 2017: Nature Protocols
https://www.readbyqxmd.com/read/28039566/the-structure-of-fcpb-a-light-harvesting-complex-in-the-diatom-cyclotella-meneghiniana
#12
Anja Röding, Egbert Boekema, Claudia Büchel
Diatoms possess fucoxanthin chlorophyll proteins (FCP) as light-harvesting systems. These membrane intrinsic proteins bind fucoxanthin as major carotenoid and Chl c as accessory chlorophyll. The relatively high sequence homology to higher plant light-harvesting complex II gave rise to the assumption of a similar overall structure. From centric diatoms like Cyclotella meneghiniana, however, two major FCP complexes can be isolated. FCPa, composed of Fcp2 and Fcp6 subunits, was demonstrated to be trimeric, whereas FCPb, known to contain Fcp5 polypeptides, is of higher oligomeric state...
December 30, 2016: Photosynthesis Research
https://www.readbyqxmd.com/read/28032953/ultrasmall-yig-nanoparticles-with-high-coercivity-at-low-temperature-synthesized-by-laser-ablation-and-fragmentation-of-pressed-powders
#13
Tim Schmitz, Ulf Wiedwald, Carsten Dubs, Bilal Gökce
Pulsed laser ablation of pressed yttrium-ion-garnet powders in water is studied and compared to the ablation of a single crystal target. We find that target porosity is a crucial factor which has far-reaching implications on nanoparticle productivity. Although nanoparticle size distributions obtained by analytical disc centrifugation and transmission electron microscopy (TEM) are in agreement, X-ray diffraction and energy dispersive X-ray analysis show that only nanoparticles obtained from targets with densities close to that of a bulk target lead to comparable properties...
December 29, 2016: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/28011114/in-situ-investigation-of-ordering-phase-transformations-in-fept-magnetic-nanoparticles
#14
James E Wittig, James Bentley, Lawrence F Allard
In situ high-resolution electron microscopy was used to reveal information at the atomic level for the disordered-to-ordered phase transformation of equiatomic FePt nanoparticles that can exhibit outstanding magnetic properties after transforming from disordered face-centered-cubic into the tetragonal L10 ordered structure. High-angle annular dark-field imaging in the scanning transmission electron microscope provided sufficient contrast between the Fe and Pt atoms to readily monitor the ordering of the atoms during in situ heating experiments...
December 11, 2016: Ultramicroscopy
https://www.readbyqxmd.com/read/28008928/cryo-electron-microscopy-structures-of-the-sars-cov-spike-glycoprotein-reveal-a-prerequisite-conformational-state-for-receptor-binding
#15
Miao Gui, Wenfei Song, Haixia Zhou, Jingwei Xu, Silian Chen, Ye Xiang, Xinquan Wang
The global outbreak of SARS in 2002-2003 was caused by the infection of a new human coronavirus SARS-CoV. The infection of SARS-CoV is mediated mainly through the viral surface glycoproteins, which consist of S1 and S2 subunits and form trimer spikes on the envelope of the virions. Here we report the ectodomain structures of the SARS-CoV surface spike trimer in different conformational states determined by single-particle cryo-electron microscopy. The conformation 1 determined at 4.3 Å resolution is three-fold symmetric and has all the three receptor-binding C-terminal domain 1 (CTD1s) of the S1 subunits in "down" positions...
January 2017: Cell Research
https://www.readbyqxmd.com/read/28007449/structural-studies-of-influenza-virus-rnps-by-electron-microscopy-indicate-molecular-contortions-within-np-supra-structures
#16
John R Gallagher, Udana Torian, Dustin M McCraw, Audray K Harris
Ribonucleoprotein (RNP) complexes of influenza viruses are composed of multiple copies of the viral nucleoprotein (NP) that can form filamentous supra-structures. RNPs package distinct viral genomic RNA segments of different lengths into pleomorphic influenza virions. RNPs also function in viral RNA transcription and replication. Different RNP segments have varying lengths, but all must be incorporated into virions during assembly and then released during viral entry for productive infection cycles. RNP structures serve varied functions in the viral replication cycle, therefore understanding their molecular organization and flexibility is essential to understanding these functions...
December 19, 2016: Journal of Structural Biology
https://www.readbyqxmd.com/read/28005321/in-situ-observation-of-single-au-triangular-nanoprism-etching-to-various-shapes-for-plasmonic-photocatalytic-hydrogen-generation
#17
Zaizhu Lou, Sooyeon Kim, Peng Zhang, Xiaowei Shi, Mamoru Fujitsuka, Tetsuro Majima
In situ etching of single Au triangular nanoprism (TNP) was successfully monitored by the plasmonic photoluminescence (PL) spectra using single-particle microscopy, which provides clear results to understand the geometric and anisotropic dependence of surface plasmon resonance in Au nanostructures. Various Au nanostructures (TNP, obtuse TNP (O-TNP) and nanodisk) were obtained to synthesize anisotropic Pt-Au as plasmonic photocatalyts for hydrogen generation. Single-particle PL spectra and finite-difference time-domain simulations demonstrate that the Pt-edged Au O-TNP has larger tip area and higher plasmon enhanced electrical field for hot electron transfer and charge separation, leading to more efficient photocatalytic hydrogen generation...
December 28, 2016: ACS Nano
https://www.readbyqxmd.com/read/28001409/shape-engineering-driven-by-selective-growth-of-sno2-on-doped-ga2o3-nanowires
#18
Manuel Alonso-Orts, Ana M Sánchez, Steven A Hindmarsh, Iñaki López, Emilio Nogales, Javier Piqueras, Bianchi Méndez
Tailoring the shape of complex nanostructures requires control of the growth process. In this work, we report on the selective growth of nanostructured tin oxide on gallium oxide nanowires leading to the formation of SnO2/Ga2O3 complex nanostructures. Ga2O3 nanowires decorated with either crossing SnO2 nanowires or SnO2 particles have been obtained in a single step treatment by thermal evaporation. The reason for this dual behavior is related to the growth direction of trunk Ga2O3 nanowires. Ga2O3 nanowires grown along the [001] direction favor the formation of crossing SnO2 nanowires...
December 23, 2016: Nano Letters
https://www.readbyqxmd.com/read/27995796/tracking-nanoparticle-diffusion-and-interaction-during-self-assembly-in-a-liquid-cell
#19
Alexander S Powers, Hong-Gang Liao, Shilpa N Raja, Noah D Bronstein, A Paul Alivisatos, Haimei Zheng
Nanoparticle self-assembly has been well studied theoretically, but it remains challenging to directly observe and quantify individual nanoparticle interactions. With our custom image analysis method, we track the trajectories of nanoparticle movement with high precision from a stack of relatively noisy images obtained using liquid cell transmission electron microscopy. In a time frame of minutes, Pt-Fe nanoparticles self-assembled into a loosely packed hcp lattice. The energetics and stability of the dynamic assembly were studied quantitatively...
December 20, 2016: Nano Letters
https://www.readbyqxmd.com/read/27991917/a-chikungunya-fever-vaccine-utilizing-an-insect-specific-virus-platform
#20
Jesse H Erasmus, Albert J Auguste, Jason T Kaelber, Huanle Luo, Shannan L Rossi, Karla Fenton, Grace Leal, Dal Y Kim, Wah Chiu, Tian Wang, Ilya Frolov, Farooq Nasar, Scott C Weaver
Traditionally, vaccine development involves tradeoffs between immunogenicity and safety. Live-attenuated vaccines typically offer rapid and durable immunity but have reduced safety when compared to inactivated vaccines. In contrast, the inability of inactivated vaccines to replicate enhances safety at the expense of immunogenicity, often necessitating multiple doses and boosters. To overcome these tradeoffs, we developed the insect-specific alphavirus, Eilat virus (EILV), as a vaccine platform. To address the chikungunya fever (CHIKF) pandemic, we used an EILV cDNA clone to design a chimeric virus containing the chikungunya virus (CHIKV) structural proteins...
December 19, 2016: Nature Medicine
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