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Single particle electron microscopy

Zhongbo Zhou, Yiting Tan, Yeyuan Roger Xiao, David C Stuckey
The distribution, composition and morphological structure of sub-visible particles and colloids (0.01-10 µm) in the supernatant of a lab-scale submerged anaerobic membrane reactor (SAnMBR), and their role in membrane fouling, was investigated. Photometric analysis showed that the supernatant and membrane foulants were dominated by particles and colloids (0.45-10 µm), which accounted for over 90% of the total organics (proteins and polysaccharides). Excitation-emission matrix (EEM) fluorescence spectra and monosaccharide analysis showed that these particles and colloids were rich in fluorescent proteins, rhamnose, ribose and arabinose, all of which could be related to cellular and extracellular substances...
October 26, 2016: Environmental Science & Technology
Nivethaa E A K, Dhanavel S, Narayanan V, Stephen A
Fluorescent CS/Ag-Au (chitosan/silver-gold) nanocomposite containing different weight percentage of Ag and Au was synthesized using the chemical reduction method. 5-Fluorouracil (5-FU) encapsulated nanocomposite was also synthesized and its cytotoxicity towards breast cancer cell lines (MCF-7) studied. The XRD pattern of the nanocomposite shows peaks of chitosan, silver and gold. The peaks corresponding to gold and silver indicate the face centered cubic structure of silver and gold nanoparticles. The polymer matrix nanocomposite structure with chitosan as the matrix and silver-gold as the filler phase is evident from the high resolution transmission electron microscopy (HRTEM) images and an increase in particle size from∼5nm to about 12nm is noticeable on encapsulation of 5-Fluorouracil (5-FU)...
October 20, 2016: International Journal of Biological Macromolecules
Payam Hayati, Ali Reza Rezvani, Ali Morsali, Pascal Retailleau, S García-Granda
Nanoparticles of two new coordination compounds, [Hg2(L)2(Br)4]n (1) and [Hg(L')(SCN)2] (2), (L=2-amino-4-methylpyridine, L'=2,6-pyridinedicarboxlic acid), have been synthesized by use of a sonochemical process and characterized by scanning electron microscopy (SEM), field emission scanning electron microscopy(FESEM), X-ray powder diffraction (XRPD), Fourier transform infrared spectroscopy (FTIR) spectroscopy and elemental analyses. The single crystal X-ray data of compounds 1 and 2 imply that the Hg(II) ions are four and five coordinated, respectively...
January 2017: Ultrasonics Sonochemistry
Ahmad Reza Bagheri, Mehrorang Ghaedi, Arash Asfaram, Ali Akbar Bazrafshan, Ramin Jannesar
The present study the ultrasound assisted adsorption of dyes in single system onto Fe3O4 magnetite nanoparticles loaded on activated carbon (Fe3O4-MNPs-AC) was described following characterization and identification of this adsorbent by conventional techniques likes field emission scanning electron microscopy, transmission electron microscopy, particle-size distribution, X-ray diffraction and Fourier transform infrared spectroscopy. A central composite design in conjunction with a response surface methodology according to f-test and t-test for recognition and judgment about significant term led to construction of quadratic model which represent relation among responses and effective terms...
January 2017: Ultrasonics Sonochemistry
Payam Hayati, Ali Reza Rezvani, Ali Morsali, Pascal Retailleau
Two new potassium coordination supramolecular compounds (2D and 1D), [K(H3L)(H2L)(H2O)]n·H2O (1) and [K(H2L')(HL')(H2O)2]·H2O (2), (L=1,3,5-tricarboxylic acid, L'=2,6-pyridinedicarboxylic acid), have been synthesized under different experimental conditions. Micrometric crystals (bulk) or nano-sized materials have been obtained depending on using the branch tube method or sonochemical irradiation. All materials have been characterized by field emission scanning electron microscopy (FE-SEM), scanning electron microscopy (SEM), powder X-ray diffraction (PXRD), FT-IR spectroscopy and elemental analyses...
January 2017: Ultrasonics Sonochemistry
Payam Hayati, AliReza Rezvani, Ali Morsali, Pascal Retailleau, Roberto Centore
Nanoparticles of two new 0D, lead(II) coordination supramolecular compounds, [Pb(L)2(I)2] (1) and [Pb(L)(L(/))(H2O)]·3H2O (2), (L=1,10-phenanthroline monohydrate, L(/)=2,6-pyridinedicarboxlic acid), have been synthesized by a sonochemical process and characterized by scanning electron microscopy (SEM), field emission scanning electron microscopy (FE-SEM), X-ray powder diffraction (XRPD), FT-IR spectroscopy and elemental analyses. The single crystal X-ray data of compounds show that the Pb ion is six coordinated in both 1 and 2...
September 7, 2016: Ultrasonics Sonochemistry
K N Sathish Yadav, Dmitry A Semchonok, Lukáš Nosek, Roman Kouřil, Geoffrey Fucile, Egbert J Boekema, Lutz A Eichacker
Photosystem I (PSI) is a pigment-protein complex required for the light-dependent reactions of photosynthesis and participates in light-harvesting and redox-driven chloroplast metabolism. Assembly of PSI into supercomplexes with light harvesting complex (LHC) II, cytochrome b6f (Cytb6f) or NAD(P)H dehydrogenase complex (NDH) has been proposed as a means for regulating photosynthesis. However, structural details about the binding positions in plant PSI are lacking. We analyzed large data sets of electron microscopy single particle projections of supercomplexes obtained from the stroma membrane of Arabidopsis thaliana...
October 15, 2016: Biochimica et Biophysica Acta
Katarzyna Szot-Karpińska, Piotr Golec, Adam Lesniewski, Barbara Palys, Frank Marken, Joanna Niedziółka-Jönsson, Grzegorz Wegrzyn, Marcin Łoś
With the advent of nanotechnology, carbon nanomaterials such as carbon nanofibers (CNF) have aroused substantial interest in various research fields including energy storage and sensing. Further improvement of their properties might be achieved via application of viral particles such as bacteriophages. In this report we present a filamentous M13 bacteriophage, with a point mutation in gene VII (pVII-mutant-M13), that selectively binds to the carbon nanofibers to form 3D structures. The phage-display technique was utilized for the selection of the pVII-mutant-M13 phage from the phage display peptide library...
October 17, 2016: Bioconjugate Chemistry
Christopher J Benjamin, Kyle J Wright, Scott C Bolton, Seok-Hee Hyun, Kyle Krynski, Mahima Grover, Guimei Yu, Fei Guo, Tamara L Kinzer-Ursem, Wen Jiang, David H Thompson
We report the fabrication of transmission electron microscopy (TEM) grids bearing graphene oxide (GO) sheets that have been modified with N(α), N(α)-dicarboxymethyllysine (NTA) and deactivating agents to block non-selective binding between GO-NTA sheets and non-target proteins. The resulting GO-NTA-coated grids with these improved antifouling properties were then used to isolate His6-T7 bacteriophage and His6-GroEL directly from cell lysates. To demonstrate the utility and simplified workflow enabled by these grids, we performed cryo-electron microscopy (cryo-EM) of His6-GroEL obtained from clarified E...
October 17, 2016: Scientific Reports
W Yu, Y Jiang, J Yang, Z L Dun, H D Zhou, Z Jiang, P Lu, W Pan
A three-dimensional (3D) Dirac semimetal (DS) is an analogue of graphene, but with linear energy dispersion in all (three) momentum directions. 3D DSs have been a fertile playground in discovering novel quantum particles, for example Weyl fermions, in solid state systems. Many 3D DSs were theoretically predicted and experimentally confirmed. We report here the results in exfoliated ZrTe5 thin flakes from the studies of aberration-corrected scanning transmission electron microscopy and low temperature magneto-transport measurements...
October 14, 2016: Scientific Reports
Igor Orlov, Alexander G Myasnikov, Leonid Andronov, S Kundhavai Natchiar, Heena Khatter, Brice Beinsteiner, Jean-François Ménétret, Isabelle Hazemann, Kareem Mohideen, Karima Tazibt, Rachel Tabaroni, Hanna Kratzat, Nadia Djabeur, Tatiana Bruxelles, Finaritra Raivoniaina, Lorenza di Pompeo, Morgan Torchy, Isabelle Billas, Alexandre Urzhumtsev, Bruno P Klaholz
After gradually moving away from preparation methods prone to artefacts such as plastic embedding and negative staining for cell sections and single particles, the field of cryo electron microscopy is now heading off at unprecedented speed towards high-resolution analysis of biological objects of various sizes. This "revolution in resolution" is happening largely thanks to new developments of new-generation cameras used for recording the images in the cryo electron microscope which have much increased sensitivity being based on CMOS devices...
October 12, 2016: Biology of the Cell
Juyeong Kim, Matthew R Jones, Zihao Ou, Qian Chen
We use liquid phase transmission electron microscopy (LP-TEM) to characterize the structure and dynamics of a solution-phase superlattice assembled from gold nanoprisms at the single particle level. The lamellar structure of the superlattice, determined by a balance of inter-prism interactions, is maintained and resolved under low-dose imaging conditions typically reserved for biomolecular imaging. In this dose range, we capture dynamic structural changes in the superlattice in real time, where contraction and smaller steady-state lattice constants are observed at higher electron dose rates...
October 10, 2016: ACS Nano
Saravanan Krishnan, Shoba Narayan, Anju Chadha
The cell free extracts of Candida parapsilosis ATCC 7330 are more efficient than the whole resting cells of the yeast in the synthesis of directly usable gold nanoparticles as revealed by this systematic study. Cell free extracts yielded gold nanoparticles of hydrodynamic diameter (50-200 nm). In this study, the total protein concentration influences the nanofabrication and not only the reductase enzymes as originally thought. Powder X-ray diffraction studies confirm the crystalline nature of the gold nanoparticles...
December 2016: AMB Express
R J G Hulswit, C A M de Haan, B-J Bosch
Coronaviruses (CoVs) have a remarkable potential to change tropism. This is particularly illustrated over the last 15 years by the emergence of two zoonotic CoVs, the severe acute respiratory syndrome (SARS)- and Middle East respiratory syndrome (MERS)-CoV. Due to their inherent genetic variability, it is inevitable that new cross-species transmission events of these enveloped, positive-stranded RNA viruses will occur. Research into these medical and veterinary important pathogens-sparked by the SARS and MERS outbreaks-revealed important principles of inter- and intraspecies tropism changes...
2016: Advances in Virus Research
En Ning Saw, Viktoria Grasmik, Christian Rurainsky, Matthias Epple, Kristina Tschulik
The increasing interest in producing bimetallic nanoparticles and utilizing them in modern technologies sets the demand for fast and affordable characterization of these materials. To date Scanning Transmission Electron Microscopy (STEM) coupled to energy dispersive X-ray spectroscopy is usually used to determine the size and composition of alloy nanoparticles, which is time-consuming and expensive. Here electrochemical single nanoparticle analysis is presented as an alternative approach to infer the particle size and composition of alloy nanoparticles, directly in a dispersion of these particles...
September 15, 2016: Faraday Discussions
Matteo Barborini, Sandro Sorella, Massimo Rontani, Stefano Corni
Scanning tunneling microscopy (STM) and spectroscopy probe the local density of states of single molecules electrically insulated from the substrate. The experimental images, although usually interpreted in terms of single-particle molecular orbitals, are associated with quasiparticle wave functions dressed by the whole electron-electron interaction. Here we propose an ab-initio approach based on quantum Monte Carlo to calculate the quasiparticle wave functions of molecules. Through the comparison between Monte Carlo wave functions and their uncorrelated Hartree-Fock counterparts we visualize the electronic correlation embedded in the simulated STM images, high-lighting the many-body features that might be observed...
October 6, 2016: Journal of Chemical Theory and Computation
Fei Zhang, Masanao Inokoshi, Maria Batuk, Joke Hadermann, Ignace Naert, Bart Van Meerbeek, Jef Vleugels
OBJECTIVE: The aim was to evaluate the optical properties, mechanical properties and aging stability of yttria-stabilized zirconia with different compositions, highlighting the influence of the alumina addition, Y2O3 content and La2O3 doping on the translucency. METHODS: Five different Y-TZP zirconia powders (3 commercially available and 2 experimentally modified) were sintered under the same conditions and characterized by X-ray diffraction with Rietveld analysis and scanning electron microscopy (SEM)...
September 30, 2016: Dental Materials: Official Publication of the Academy of Dental Materials
Eva Nogales, Robert K Louder, Yuan He
Single particle cryo-Electron Microscopy (cryo-EM) is a technique that allows the structural characterization of macromolecules without the need for crystallization. For certain type of samples that are ideally suited for cryo-EM studies it has been possible to reach high-resolution structures following relatively standard procedures. Other biological systems remain highly challenging, even for cryo-EM. Challenges may involve the scarcity of the sample, poor stability of the complexes, and most often, the intrinsic flexibility of biological molecules...
September 30, 2016: Current Opinion in Structural Biology
Tanmay A M Bharat, Sjors H W Scheres
Electron cryo-tomography (cryo-ET) is a technique that is used to produce 3D pictures (tomograms) of complex objects such as asymmetric viruses, cellular organelles or whole cells from a series of tilted electron cryo-microscopy (cryo-EM) images. Averaging of macromolecular complexes found within tomograms is known as subtomogram averaging, and this technique allows structure determination of macromolecular complexes in situ. Subtomogram averaging is also gaining in popularity for the calculation of initial models for single-particle analysis...
November 2016: Nature Protocols
Yoshimasa Takizawa, Elad Binshtein, Amanda L Erwin, Tasia M Pyburn, Kathleen F Mittendorf, Melanie D Ohi
Single-particle cryo-electron microscopy (EM) is currently gaining attention for the ability to calculate structures that reach sub-5 Å resolutions; however, the technique is more than just an alternative approach to X-ray crystallography. Molecular machines work via dynamic conformational changes, making structural flexibility the hallmark of function. While the dynamic regions in molecules are essential, they are also the most challenging to structurally characterize. Single-particle EM has the distinct advantage of being able to directly visualize purified molecules without the formation of ordered arrays of molecules locked into identical conformations...
October 6, 2016: Protein Science: a Publication of the Protein Society
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