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https://www.readbyqxmd.com/read/28646653/cryo-em-beyond-the-microscope
#1
REVIEW
Lesley A Earl, Veronica Falconieri, Jacqueline Ls Milne, Sriram Subramaniam
The pace at which cryo-EM is being adopted as a mainstream tool in structural biology has continued unabated over the past year. Initial successes in obtaining near-atomic resolution structures with cryo-EM were enabled to a large extent by advances in microscope and detector technology. Here, we review some of the complementary technical improvements that are helping sustain the cryo-EM revolution. We highlight advances in image processing that permit high resolution structure determination even in the presence of structural and conformational heterogeneity...
June 21, 2017: Current Opinion in Structural Biology
https://www.readbyqxmd.com/read/28646521/enhancing-perovskite-electrocatalysis-of-solid-oxide-cells-through-controlled-growth-of-nanoparticles
#2
Bin Hua, Meng Li, Yi-Fei Sun, Jian-Hui Li, Jing-Li Luo
Perovskite oxides have received a great deal of attentions as promising electrodes in both solid oxide fuel cells (SOFCs) and solid oxide electrolyzer cells (SOECs) because of their reasonable reactivity, impurity tolerance, tunable property, etc. Particular explorations are still required for advancing the perovskite electrodes, which normally suffer from slow kinetics in electrocatalysis. In the past decades, several experimental studies have developed new classes of perovskites with advanced characteristics and electrode kinetics at technical levels...
June 24, 2017: ChemSusChem
https://www.readbyqxmd.com/read/28646222/effects-of-chemical-alternation-on-damage-accumulation-in-concentrated-solid-solution-alloys
#3
Mohammad W Ullah, Haizhou Xue, Gihan Velisa, Ke Jin, Hongbin Bei, William J Weber, Yanwen Zhang
Single-phase concentrated solid-solution alloys (SP-CSAs) have recently gained unprecedented attention due to their promising properties. To understand effects of alloying elements on irradiation-induced defect production, recombination and evolution, an integrated study of ion irradiation, ion beam analysis and atomistic simulations are carried out on a unique set of model crystals with increasing chemical complexity, from pure Ni to Ni80Fe20, Ni50Fe50, and Ni80Cr20 binaries, and to a more complex Ni40Fe40Cr20 alloy...
June 23, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28646173/transmembrane-interactions-of-full-length-mammalian-bitopic-cytochrome-p450-cytochrome-b5-complex-in-lipid-bilayers-revealed-by-sensitivity-enhanced-dynamic-nuclear-polarization-solid-state-nmr-spectroscopy
#4
Kazutoshi Yamamoto, Marc A Caporini, Sang-Choul Im, Lucy Waskell, Ayyalusamy Ramamoorthy
The dynamic protein-protein and protein-ligand interactions of integral bitopic membrane proteins with a single membrane-spanning helix play a plethora of vital roles in the cellular processes associated with human health and diseases, including signaling and enzymatic catalysis. While an increasing number of high-resolution structural studies of membrane proteins have successfully manifested an in-depth understanding of their biological functions, intact membrane-bound bitopic protein-protein complexes pose tremendous challenges for structural studies by crystallography or solution NMR spectroscopy...
June 23, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28646137/three-dimensional-multi-doped-porous-carbon-graphene-derived-from-sewage-sludge-with-template-assisted-fe-pillared-montmorillonite-for-enhanced-oxygen-reduction-reaction
#5
Meiqing Chen, Pingxiao Wu, Liya Chen, Shanshan Yang, Langfeng Yu, Yuefei Ding, Nengwu Zhu, Zhenqing Shi, Zehua Liu
Three-dimensional multi-doped porous carbon/graphene (Fe-Mt-SS-C) was prepared by carbonization of sewage sludge with template-assisted Fe-pillared montmorillonite. The material consisted of nanosheet- and particle- carbon had a high specific surface area (784.46 m(2)·g(-1)) and hierarchical porous structure of micro-, meso- and macropores. The prepared Fe-Mt-SS-C had a high degree of graphitization and large amount of defect atoms. The pyrolysis process made full use of the C, N, Fe, and S by turning them into the carbon framework of the as-obtained material in situ...
June 23, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28645851/nanotubes-connecting-b-lymphocytes-high-impact-of-differentiation-dependent-lipid-composition-on-their-growth-and-mechanics
#6
Eszter A Tóth, Ádám Oszvald, Mária Péter, Gábor Balogh, Anikó Osteikoetxea-Molnár, Tamás Bozó, Edina Szabó-Meleg, Miklós Nyitrai, Imre Derényi, Miklós Kellermayer, Toshiyuki Yamaji, Kentaro Hanada, László Vígh, János Matkó
Nanotubes (NTs) are thin, long membranous structures forming novel, yet poorly known communication pathways between various cell types. Key mechanisms controlling their growth still remained poorly understood. Since NT-forming capacity of immature and mature B cells was found largely different, we investigated how lipid composition and molecular order of the membrane affect NT-formation. Screening B cell lines with various differentiation stages revealed that NT-growth linearly correlates with membrane ganglioside levels, while it shows maximum as a function of cholesterol level...
June 20, 2017: Biochimica et Biophysica Acta
https://www.readbyqxmd.com/read/28645515/adaptations-in-rod-outer-segment-disc-membranes-in-response-to-environmental-lighting-conditions
#7
Tatini Rakshit, Subhadip Senapati, Vipul M Parmar, Bhubanananda Sahu, Akiko Maeda, Paul S H Park
The light-sensing rod photoreceptor cell exhibits several adaptations in response to the lighting environment. While adaptations to short-term changes in lighting conditions have been examined in depth, adaptations to long-term changes in lighting conditions are less understood. Atomic force microscopy was used to characterize the structure of rod outer segment disc membranes, the site of photon absorption by the pigment rhodopsin, to better understand how photoreceptor cells respond to long-term lighting changes...
June 20, 2017: Biochimica et Biophysica Acta
https://www.readbyqxmd.com/read/28645148/a-soft-environmental-control-effect-of-apatite-doped-with-mineral-traces-in-the-fowl-droppings
#8
M Minamisawa, T Taniai, S Yoshida
Fowl-dropping apatite (Ca10-z[PO4]6-z[OH]2-z) synthesized from carbonized, incinerated fowl droppings contains PO4 and OH groups that are partially substituted by CO32- ions. It shows stronger ion conductivity than commercially available hydroxyapatite in a wide range of temperatures from 23°C to 800°C. Fowl-dropping apatite readily adsorbs NO2 and SO2 gases and, without re-releasing these gases, slowly decomposes them at room temperature under sunlight via ultraviolet-visible (UV-Vis) irradiation. A limited amount of minerals and organics contained in fowl droppings causes light-induced activities in fowl-dropping apatite with a crystal structure that has a developed c face; this initiates excitation-induced atomic transfer on the solid surface derived from PO4 exposed on the c face, which then advances the decomposition reaction...
June 21, 2017: Poultry Science
https://www.readbyqxmd.com/read/28645083/graphene-oxide-nanosheets-induce-dna-damage-and-activate-the-base-excision-repair-ber-signaling-pathway-both-in%C3%A2-vitro-and-in%C3%A2-vivo
#9
Chun-Jiao Lu, Xue-Feng Jiang, Muhammad Junaid, Yan-Bo Ma, Pan-Pan Jia, Hua-Bin Wang, De-Sheng Pei
Graphene oxide (GO) has widespread concerns in the fields of biological sciences and medical applications. Currently, studies have reported that excessive GO exposure can cause cellular DNA damage through reactive oxygen species (ROS) generation. However, DNA damage mediated response of the base excision repair (BER) pathway due to GO exposure is not elucidated yet. Therefore, we exposed HEK293T cells and zebrafish embryos to different concentrations of GO for 24 h, and transcriptional profiles of BER pathway genes, DNA damage, and cell viability were analyzed both in vitro and in vivo...
June 14, 2017: Chemosphere
https://www.readbyqxmd.com/read/28645037/slip-additive-migration-surface-morphology-and-performance-on-injection-moulded-high-density-polyethylene-closures
#10
Nabeen Dulal, Robert Shanks, Thomas Gengenbach, Harsharn Gill, David Chalmers, Benu Adhikari, Isaac Pardo Martinez
HYPOTHESIS: The amount and distribution of slip agents, erucamide, and behenamide, on the surface of high-density polyethene, is determined by integral characteristics of slip agent structure and polymer morphology. A suite of surface analysis techniques was applied to correlate physicochemical properties with slip-additive migration behaviour and their surface morphology. The migration, surface morphology and physicochemical properties of the slip additives, crystallinity and orientation of polyethene spherulites and interaction between slip additives and high-density polyethene influence the surface characteristics...
June 13, 2017: Journal of Colloid and Interface Science
https://www.readbyqxmd.com/read/28644908/photoactive-surface-grafted-polymer-brushes-with-phthalocyanine-bridging-groups-as-an-advanced-architecture-for-light-harvesting
#11
Michał Szuwarzyński, Karol Wolski, Agata Pomorska, Tomasz Uchacz, Arkadiusz Gut, Łukasz Łapok, Szczepan Zapotoczny
Surface-grafted polymer brushes of novel ladder-like architecture were proposed for inducing ordering of chromophores embedded therein. The brushes with acetylene side groups were obtained by surface-initiated photoiniferter-mediated polymerization. The acetylene moieties reacted then via "click" process with an axially azide-bifunctionalized silicon phthalocyanine bridging the neighboring chains that inherently adopt extended conformations in dense brushes. FTIR, quartz crystal microbalance, atomic force microscopy were used to study formation and structure of the photoactive brushes varying in grafting densities...
June 23, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28644811/applying-pattern-recognition-to-high-resolution-images-to-determine-cellular-signaling-status
#12
Michael F Lohrer, Darrin M Hanna, Yang Liu, Kang-Hsin Wang, Fu-Tong Liu, Ted A Laurence, Gang-Yu Liu
Two frequently used tools to acquire high-resolution images of cells are scanning electron microscopy (SEM) and atomic force microscopy (AFM). The former provides a nanometer resolution view of cellular features rapidly and with high throughput, while the latter enables visualizing hydrated and living cells. In current practice, these images are viewed by eye to determine cellular status, e.g. activated versus resting. Automatic and quantitative data analysis is lacking. This work develops an algorithm of pattern recognition that works very effectively for AFM and SEM images...
June 21, 2017: IEEE Transactions on Nanobioscience
https://www.readbyqxmd.com/read/28644655/formation-of-vacancies-in-si-and-ge-based-clathrates-role-of-electron-localization-and-symmetry-breaking
#13
Amrita Bhattacharya, Christian Carbogno, Bodo Böhme, Michael Baitinger, Yuri Grin, Matthias Scheffler
The formation of framework vacancies in Si- and Ge-based type-I clathrates is studied using density-functional theory as a function of filling the cages with K and Ba atoms. Our analysis reveals the relevance of structural disorder, geometric relaxation, and electronic saturation as well as vibrational and configurational entropy. In the Si clathrates, we find that vacancies are unstable, but very differently, in Ge clathrates, up to three vacancies per unit cell can be stabilized. This contrasting behavior is largely driven by the different energy gain on populating the electronic vacancy states, which originates from the different degree of localization of the valence orbitals of Si and Ge...
June 9, 2017: Physical Review Letters
https://www.readbyqxmd.com/read/28644653/dielectric-anisotropy-of-the-gap-si-001-interface-from-first-principles-theory
#14
Pankaj Kumar, Charles H Patterson
First-principles calculations of the dielectric anisotropy of the GaP/Si(001) interface are compared to the anisotropy extracted from reflectance measurements on GaP thin films on Si(001) [O. Supplie et al., Phys. Rev. B 86, 035308 (2012)PRBMDO1098-012110.1103/PhysRevB.86.035308]. Optical excitations from two states localized in several Si layers adjacent to the interface result in the observed anisotropy of the interface. The calculations show excellent agreement with experiment only for a gapped interface with a P layer in contact with Si and show that a combination of theory and experiment can reveal localized electronic states and the atomic structure at buried interfaces...
June 9, 2017: Physical Review Letters
https://www.readbyqxmd.com/read/28644612/suppressing-isomerization-of-phosphine-protected-au9-cluster-by-bond-stiffening-induced-by-a-single-pd-atom-substitution
#15
Seiji Yamazoe, Shota Matsuo, Satoru Muramatsu, Shinjiro Takano, Kiyofumi Nitta, Tatsuya Tsukuda
The fluxional nature of small gold clusters has been exemplified by reversible isomerization between [Au9(PPh3)8](3+) with a crown motif (Au9(C)) and that with a butterfly motif (Au9(B)) induced by association and dissociation with compact counteranions (NO3(-), Cl(-)). However, structural isomerization was suppressed by substitution of the central Au atom of the Au9 core in [Au9(PPh3)8](3+) with a Pd atom: [PdAu8(PPh3)8](2+) with a crown motif (PdAu8(C)) did not isomerize to that with a butterfly motif (PdAu8(B)) upon association with the counteranions...
June 23, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28644563/gas-phase-dissociation-study-of-erythrinian-alkaloids-by-electrospray-ionization-mass-spectrometry-and-computational-methods
#16
T Guaratini, L G P Feitosa, D B Silva, N P Lopes, J L C Lopes, R Vessecchi
Alkaloids from plants of the genus Erythrina display important biological activities, including anxiolytic action. Characterization of these alkaloids by mass spectrometry (MS) has contributed to the construction of a spectral library, has improved understanding of their structures, and has supported the proposal of fragmentation mechanisms in light of density functional calculations (DFT). In this study, we have used low- and high-resolution MS(n) analyses to investigate the fragmentation patterns of erythrinian alkaloids; we have employed the B3LYP/6-31+G(d,p) model to obtain their reactive sites...
June 23, 2017: Journal of Mass Spectrometry: JMS
https://www.readbyqxmd.com/read/28644553/structural-insights-into-the-inclusion-complexes-between-clomiphene-citrate-and-%C3%AE-cyclodextrin-the-mechanism-of-preferential-isomeric-selection
#17
Arti Maheshwari, Harish Saraswat, Santosh Kumar Upadhyay
A major challenge in pharmaceuticals for clinical applications is to alter the solubility, stability, and toxicity of drug molecules in living systems. Cyclodextrins (CDs) have the ability to form host-guest inclusion complexes with pharmaceuticals for further development of new drug formulations. The inclusion complex of clomiphene citrate (CL), a poorly water-soluble drug, with native β-cyclodextrin (β-CD) was characterized by a one and two-dimensional nuclear magnetic resonance (NMR) spectroscopic approach and also by molecular docking techniques...
June 23, 2017: Chirality
https://www.readbyqxmd.com/read/28644502/au3-%C3%AE-3-s-0e-elementary-block-new-insights-into-ligated-gold-clusters-with-%C3%AE-3-sulfido-motifs
#18
Wen Wu Xu, Xiao Cheng Zeng, Yi Gao
An understanding of the structural stability and formation mechanism of ligated gold nanoclusters with triply coordinated μ3-sulfido (μ3-S) motifs is important not only for gold chemistry but also for the design of more effective catalysts or drug carriers for various applications. In this article, a new elementary block Au3(μ3-S) with zero valence electrons [referred to as Au3(μ3-S)(0e)] has been identified, which describes all crystallized ligated gold clusters with μ3-S motifs, in conjunction with the previously reported Au3(2e) and Au4(2e) elementary blocks, in a grand unified model (GUM)...
June 23, 2017: Nanoscale
https://www.readbyqxmd.com/read/28644475/post-translational-modification-of-ribosomally-synthesized-peptides-by-a-radical-sam-epimerase-in-bacillus-subtilis
#19
Alhosna Benjdia, Alain Guillot, Pauline Ruffié, Jérôme Leprince, Olivier Berteau
Ribosomally synthesized peptides are built out of L-amino acids, whereas D-amino acids are generally the hallmark of non-ribosomal synthetic processes. Here we show that the model bacterium Bacillus subtilis is able to produce a novel type of ribosomally synthesized and post-translationally modified peptide that contains D-amino acids, and which we propose to call epipeptides. We demonstrate that a two [4Fe-4S]-cluster radical S-adenosyl-L-methionine (SAM) enzyme converts L-amino acids into their D-counterparts by catalysing Cα-hydrogen-atom abstraction and using a critical cysteine residue as the hydrogen-atom donor...
July 2017: Nature Chemistry
https://www.readbyqxmd.com/read/28644474/%C3%AF-electron-s%C3%A2-%C3%A2-%C3%A2-quantum-spin-liquid-state-in-an-ionic-polyaromatic-hydrocarbon
#20
Yasuhiro Takabayashi, Melita Menelaou, Hiroyuki Tamura, Nayuta Takemori, Takashi Koretsune, Aleš Štefančič, Gyöngyi Klupp, A Johan C Buurma, Yusuke Nomura, Ryotaro Arita, Denis Arčon, Matthew J Rosseinsky, Kosmas Prassides
Molecular solids with cooperative electronic properties based purely on π electrons from carbon atoms offer a fertile ground in the search for exotic states of matter, including unconventional superconductivity and quantum magnetism. The field was ignited by reports of high-temperature superconductivity in materials obtained by the reaction of alkali metals with polyaromatic hydrocarbons, such as phenanthrene and picene, but the composition and structure of any compound in this family remained unknown. Here we isolate the binary caesium salts of phenanthrene, Cs(C14H10) and Cs2(C14H10), to show that they are multiorbital strongly correlated Mott insulators...
July 2017: Nature Chemistry
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