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https://www.readbyqxmd.com/read/29147699/strain-relaxation-and-ambipolar-electrical-transport-in-gaas-insb-core-shell-nanowires
#1
Torsten Rieger, Patrick Zellekens, Natalia Demarina, Ali Al Hassan, Franz Josef Hackemüller, Hans Lüth, Ullrich Pietsch, Thomas Schäpers, Detlev Grützmacher, Mihail Ion Lepsa
The growth, crystal structure, strain relaxation and room temperature transport characteristics of GaAs/InSb core-shell nanowires grown using molecular beam epitaxy are investigated. Due to the large lattice mismatch between GaAs and InSb of 14%, a transition from island-based to layer-like growth occurs during the formation of the shell. High resolution transmission electron microscopy in combination with geometric phase analyses as well as X-ray diffraction with synchrotron radiation are used to investigate the strain relaxation and prove the existence of different dislocations relaxing the strain on zinc blende and wurtzite core-shell nanowire segments...
November 17, 2017: Nanoscale
https://www.readbyqxmd.com/read/29144454/dynamics-of-p-type-atpase-transport-revealed-by-single-molecule-fret
#2
Mateusz Dyla, Daniel S Terry, Magnus Kjaergaard, Thomas L-M Sørensen, Jacob Lauwring Andersen, Jens Peter Andersen, Charlotte Rohde Knudsen, Roger B Altman, Poul Nissen, Scott C Blanchard
Phosphorylation-type (P-type) ATPases are ubiquitous primary transporters that pump cations across cell membranes through the formation and breakdown of a phosphoenzyme intermediate. Structural investigations suggest that the transport mechanism is defined by conformational changes in the cytoplasmic domains of the protein that are allosterically coupled to transmembrane helices so as to expose ion binding sites to alternate sides of the membrane. Here, we have used single-molecule fluorescence resonance energy transfer to directly observe conformational changes associated with the functional transitions in the Listeria monocytogenes Ca(2+)-ATPase (LMCA1), an orthologue of eukaryotic Ca(2+)-ATPases...
November 16, 2017: Nature
https://www.readbyqxmd.com/read/29143814/structural-basis-of-nucleotide-sugar-transport-across-the-golgi-membrane
#3
Joanne L Parker, Simon Newstead
Glycosylation is a fundamental cellular process that, in eukaryotes, occurs in the lumen of both the Golgi apparatus and the endoplasmic reticulum. Nucleotide sugar transporters (NSTs) are an essential component of the glycosylation pathway, providing the diverse range of substrates required for the glycosyltransferases. NSTs are linked to several developmental and immune disorders in humans, and in pathogenic microbes they have an important role in virulence. How NSTs recognize and transport activated monosaccharides, however, is currently unclear...
November 15, 2017: Nature
https://www.readbyqxmd.com/read/29142314/magnetoresistance-and-robust-resistivity-plateau-in-moas2
#4
Jialu Wang, Lin Li, Wei You, Tingting Wang, Chao Cao, Jianhui Dai, Yuke Li
We have grown the MoAs2 single crystal which crystallizes in a monoclinic structure with C2/m space group. Transport measurements show that MoAs2 displays a metallic behavior at zero field and undergoes a metal-to-semiconductor crossover at low temperatures when the applied magnetic field is over 5 T. A robust resistivity plateau appears below 18 K and persists for the field up to 9 T. A large positive magnetoresistance (MR), reaching about 2600% at 2 K and 9 T, is observed when the field is perpendicular to the current...
November 15, 2017: Scientific Reports
https://www.readbyqxmd.com/read/29139156/characterization-of-cysteine-thiol-modifications-based-on-protein-microenvironments-and-local-secondary-structures
#5
Akshay Bhatnagar, Debashree Bandyopadhyay
We have demonstrated earlier that protein microenvironments were conserved around disulphide-bridged cystine motifs with similar functions, irrespective of diversity in protein sequences (Bhatnagar et al., 2016; 84:1576-1589) . Here, cysteine thiol modifications were characterized based on protein microenvironments, secondary structures and specific protein functions. Protein microenvironment around an amino acid was defined as the summation of hydrophobic contributions from the surrounding protein fragments and the solvent molecules present within its first contact shell (Bandyopadhyay and Mehler, Proteins 2008; 72:646-659)...
November 15, 2017: Proteins
https://www.readbyqxmd.com/read/29137892/role-of-pyrophosphate-in-vascular-calcification-in-chronic-kidney-disease
#6
Daniel Azpiazu, Sergio Gonzalo, Emilio González-Parra, Jesús Egido, Ricardo Villa-Bellosta
Vascular calcification is a pathology characterized by the deposition of calcium-phosphate in cardiovascular structures, mainly in the form of hydroxyapatite crystals, resulting in ectopic calcification. It is correlated with increased risk of cardiovascular disease and myocardial infarction in diabetic patients and in those with chronic kidney disease (CKD). Vascular smooth muscle cells are sensitive to changes in inorganic phosphate (Pi) levels. They are able to adapt and modify some of their functions and promote changes which trigger calcification...
November 11, 2017: Nefrología: Publicación Oficial de la Sociedad Española Nefrologia
https://www.readbyqxmd.com/read/29135241/the-antibiotic-novobiocin-binds-and-activates-the-atpase-that-powers-lipopolysaccharide-transport
#7
Janine M May, Tristan Wold Owens, Michael Dan Mandler, Brent W Simpson, Michael Lazarus, David J Sherman, Rebecca M Davis, Suguru Okuda, Walter Massefski, Natividad Ruiz, Daniel Kahne
Most natural product antibiotics are well known for one mecha-nism of action. Novobiocin is an orally active antibiotic that in-hibits DNA gyrase by binding the ATP-binding site in the ATPase subunit. Although effective against Gram-positive pathogens, novobiocin has limited activity against Gram-negative organisms due to the presence of the lipopolysaccharide-containing outer membrane, which acts as a permeability barrier. Using a novobi-ocin-sensitive Escherichia coli strain with a leaky outer membrane, we identified a mutant with increased resistance to novobiocin...
November 14, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/29134224/substitution-of-re-7-into-camno3-an-efficient-free-electron-generation-dopant-for-tuning-of-thermoelectric-properties
#8
J Felix Shin, Hongjun Niu, Jonathan Alaria, John B Claridge, Matthew J Rosseinsky
Highly dense CaMn1-xRexO3 (0 ≤ x ≤ 0.04) samples were prepared by solid-state synthesis. The effect of Re doping was assessed by the characterisation of crystal structure, oxygen content, and electrical and thermal transport properties. The oxidation state of the substituted Re was determined by X-ray absorption near edge spectra to be Re(7+), and led to expansion of the lattice and an increase in electron carrier concentration due to the formation of Mn(3+). The thermal behaviour of the electrical conductivity and the thermopower over a wide temperature range allowed identification of different conduction mechanisms: (1) below 110 K, 3D variable range hopping, (2) between 110 and 650 K, small polaron transport, and (3) above 650 K, activation of carriers over a mobility edge...
November 14, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/29130898/single-step-synthesis-of-er-3-and-yb-3-ions-doped-molybdate-gd2o3-core-shell-nanoparticles-for-biomedical-imaging
#9
Izabela Kaminska, Danek Elbaum, Bozena Sikora, Przemysław Kowalik, Jakub Mikulski, Zofia Felcyn, Piotr Samol, Tomasz Wojciechowski, Roman Minikayev, Wojciech Paszkowicz, Wojciech Zaleszczyk, Maciej Szewczyk, Anna Konopka, Grzegorz Gruzeł, Mirosława Pawlyta, Mikołaj Donten, Kamil Ciszak, Karolina Zajdel, Małgorzata Baniewicz, Piotr Stępień, Mariusz Łapiński, Grzegorz Wilczyński, Krzysztof Fronc
Nanostructures as color-tunable luminescent markers have become major, promising tools for bioimaging and biosensing. The separated molybdate/Gd2O3 doped rare earth ions (erbium, Er(3+) and ytterbium, Yb(3+)) core-shell nanoparticles (NPs), were fabricated by a one step homogeneous precipitation process. Emission properties were studied by cathodo- and photoluminescence. The scanning electron and transmission electron microscopes were used to visualize and to determine the size and shape of the NPs. The spherical NPs were obtained...
November 13, 2017: Nanotechnology
https://www.readbyqxmd.com/read/29130892/surface-effects-on-ionic-coulomb-blockade-in-nanometer-size-pores
#10
Hiroya Tanaka, Hideo Iizuka, Yuriy V Pershin, Massimiliano Di Ventra
Ionic Coulomb blockade in nanopores is a phenomenon that shares some similarities but also differences with its electronic ounterpart. Here, we investigate extensively this phenomenon using all-atom molecular dynamics of ionic transport through nanopores of about one nanometer in diameter and up to several nanometers in length. Our goal is to better understand the role of atomic roughness and structure of the pore walls in facilitating ionic Coulomb blockade. Our numerical results reveal the following general trends...
November 13, 2017: Nanotechnology
https://www.readbyqxmd.com/read/29130455/structure-magnetism-and-electronic-properties-in-3d-5d-based-double-perovskite-formula-see-text-y-x-2feiro6
#11
K C Kharkwal, A K Pramanik
The 3d-5d based double perovskites are of current interest as they provide model systems to study the interplay between electronic correlation (U) and spin-orbit coupling (SOC). Here, we report detailed structural, magnetic and transport properties of doped double perovskite material ([Formula: see text]Y x )2FeIrO6 with [Formula: see text]. With substitution of Y, the system retains its original crystal structure but structural parameters change with x in nonmonotonic fashion. The magnetization data for Sr2FeIrO6 show antiferromagnetic type magnetic transition around 45 K; however, a close inspection of the data indicates a weak magnetic phase transition around 120 K...
November 13, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
https://www.readbyqxmd.com/read/29129383/the-structure-of-a-conserved-domain-of-tamb-reveals-a-hydrophobic-%C3%AE-taco-fold
#12
Inokentijs Josts, Christopher James Stubenrauch, Grishma Vadlamani, Khedidja Mosbahi, Daniel Walker, Trevor Lithgow, Rhys Grinter
The translocation and assembly module (TAM) plays a role in the transport and insertion of proteins into the bacterial outer membrane. TamB, a component of this system spans the periplasmic space to engage with its partner protein TamA. Despite efforts to characterize the TAM, the structure and mechanism of action of TamB remained enigmatic. Here we present the crystal structure of TamB amino acids 963-1,138. This region represents half of the conserved DUF490 domain, the defining feature of TamB. TamB963-1138 consists of a concave, taco-shaped β sheet with a hydrophobic interior...
November 3, 2017: Structure
https://www.readbyqxmd.com/read/29128838/transfection-of-plasmid-dna-by-nanocarriers-containing-a-gemini-cationic-lipid-with-an-aromatic-spacer-or-its-monomeric-counterpart
#13
María Martínez-Negro, Ana L Barrán-Berdón, Clara Aicart-Ramos, María L Moyá, Conchita Tros de Ilarduya, Emilio Aicart, Elena Junquera
This study performed a biophysical characterization (electrochemistry, structure and morphology) and assessment of the biological activity and cell biocompatibility of GCL/DOPE-pDNA lipoplexes comprised of plasmid DNA and a mixed lipid formed by a DOPE zwitterionic lipid and a gemini cationic lipid N-N'-(1,3-phenylene bis (methylene)) bis (N,N-dimethyl-N-(1-dodecyl) ammonium dibromide (12PH12) containing an aromatic spacer or its monomeric counterpart surfactant, N-benzyl-N,N-dimethyl-N-(1-dodecyl) ammonium bromide (12PH)...
November 8, 2017: Colloids and Surfaces. B, Biointerfaces
https://www.readbyqxmd.com/read/29127253/first-biochemical-and-crystallographic-characterization-of-a-fast-performing-ferritin-from-a-marine-invertebrate
#14
E De Meulenaere, J B Bailey, F A Tezcan, D D Deheyn
Ferritin, a multimeric cage-like enzyme, is integral to iron metabolism across all phyla through the sequestration and storage of iron through efficient ferroxidase activity. While ferritin sequences from around 900 species have been identified, crystal structures from only 50 species have been reported, the majority from bacterial origin. We recently isolated a secreted ferritin from the marine invertebrate Chaetopterus sp. (parchment tubeworm), which resides in muddy coastal seafloors. Here, we present the first ferritin from a marine invertebrate to be crystallized, and its biochemical characterization...
November 10, 2017: Biochemical Journal
https://www.readbyqxmd.com/read/29120611/bulk-kosterlitz-thouless-type-molecular-superconductor-%C3%AE-%C3%A2-bedt-ttf-2-h2o-nh4-2cr-c2o4-3-%C3%A2-18-crown-6
#15
Lee Martin, Jordan R Lopez, Hiroki Akutsu, Yasuhiro Nakazawa, Shusaku Imajo
A new molecular superconductor, β″-(BEDT-TTF)2[(H2O)(NH4)2Cr(C2O4)3]·18-crown-6, has been synthesized from the organic donor molecule BEDT-TTF with the anion Cr(C2O4)3(3-). The crystal structure consists of conducting organic layers of BEDT-TTF molecules which adopt the β″ packing motif (layer A), layers of NH4(+) and Λ-Cr(C2O4)3(3-) (layer B), layers of (H2O)(NH4)18-crown-6 (layer C), and layers of NH4(+) and Δ-Cr(C2O4)3(3-) (layer D) which produce a superstructure with a repeating pattern of ABCDABCDA...
November 9, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/29120604/molecular-determinants-for-substrate-interactions-with-the-glycine-transporter-glyt2
#16
Jane E Carland, Michael Thomas, Shannon N Mostyn, Nandhitha Subramanian, Megan Louise O'Mara, Renae M Ryan, Robert J Vandenberg
Transporters in the SLC6 family play key roles in regulating neurotransmission and are the targets for a wide range of therapeutics. Important insights into the transport mechanisms and the specificity of drug interactions of SLC6 transporters have been obtained from the crystal structures of a bacterial homolog of the family, LeuTAa, and more recently the Drosophila dopamine transporter and the human serotonin transporter. However, there is disputed evidence that the bacterial leucine transporter, LeuTAa, contains two substrate binding sites that work cooperatively in the mechanism of transport, with the binding of a second substrate being required for the release of the substrate from the primary site...
November 9, 2017: ACS Chemical Neuroscience
https://www.readbyqxmd.com/read/29118749/hoisting-loop-in-bacterial-multidrug-exporter-acrb-is-a-highly-flexible-hinge-that-enables-the-large-motion-of-the-subdomains
#17
Martijn Zwama, Katsuhiko Hayashi, Keisuke Sakurai, Ryosuke Nakashima, Kimie Kitagawa, Kunihiko Nishino, Akihito Yamaguchi
The overexpression of RND-type exporters is one of the main causes of multidrug resistance (MDR) in Gram-negative pathogens. In RND transporters, such as Escherichia coli's main efflux pump AcrB, drug efflux occurs in the porter domain, while protons flow through the transmembrane domain: remote conformational coupling. At the border of a transmembrane helix (TM8) and subdomain PC2, there is a loop which makes a hoisting movement by a random-coil-to-α-helix change, and opens and closes a drug channel entrance...
2017: Frontiers in Microbiology
https://www.readbyqxmd.com/read/29118341/novel-serotonin-transporter-regulators-natural-aristolane-and-nardosinane-types-of-sesquiterpenoids-from-nardostachys-chinensis-batal
#18
Ying-Peng Chen, Shu-Song Ying, Hong-Hong Zheng, Yan-Ting Liu, Zhong-Ping Wang, Hu Zhang, Xu Deng, Yi-Jing Wu, Xiu-Mei Gao, Tian-Xiang Li, Yan Zhu, Yan-Tong Xu, Hong-Hua Wu
Serotonin transporter (SERT) is a classic target of drug discovery for neuropsychiatric and digestive disorders, and against those disorders, plants of Nardostachys genus have been valued for centuries in the systems of Traditional Chinese Medicine, Ayurvedic and Unani. Herein, chemical investigation on the roots and rhizomes of Nardostachys chinensis Batal. led to the isolation of forty sesquiterpenoids including six new aristolane-type sesquiterpenoids and six new nardosinane-type sesquiterprenoids. Their structures were elucidated by extensive spectroscopic methods, combined with analyses of circular dichroism and single-crystal X-ray diffraction data...
November 8, 2017: Scientific Reports
https://www.readbyqxmd.com/read/29117682/constant-ph-molecular-dynamics-reveals-how-proton-release-drives-the-conformational-transition-of-a-transmembrane-efflux-pump
#19
Zhi Yue, Wei Chen, Helen I Zgurskaya, Jana Shen
AcrB is the inner-membrane transporter of E. coli AcrAB-TolC tripartite efflux complex, which plays a major role in the intrinsic resistance to clinically important antibiotics. AcrB pumps a wide range of toxic substrates by utilizing the proton gradient between periplasm and cytoplasm. Crystal structures of AcrB revealed three distinct conformational states of the transport cycle, substrate access, binding and extrusion, or loose (L), tight (T) and open (O) states. However, the specific residue(s) responsible for proton binding/release and the mechanism of proton-coupled conformational cycling remain controversial...
November 9, 2017: Journal of Chemical Theory and Computation
https://www.readbyqxmd.com/read/29117136/magnetic-nanoparticle-assisted-tunable-optical-patterns-from-spherical-cholesteric-liquid-crystal-bragg-reflectors
#20
Yali Lin, Yujie Yang, Yuwei Shan, Lingli Gong, Jingzhi Chen, Sensen Li, Lujian Chen
Cholesteric liquid crystals (CLCs) exhibit selective Bragg reflections of circularly polarized (CP) light owing to their spontaneous self-assembly abilities into periodic helical structures. Photonic cross-communication patterns could be generated toward potential security applications by spherical cholesteric liquid crystal (CLC) structures. To endow these optical patterns with tunability, we fabricated spherical CLC Bragg reflectors in the shape of microshells by glass-capillary microfluidics. Water-soluble magnetofluid with Fe₃O₄ nanoparticles incorporated in the inner aqueous core of CLC shells is responsible for the non-invasive transportable capability...
November 8, 2017: Nanomaterials
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