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https://www.readbyqxmd.com/read/28922641/structural-luminescence-thermodynamic-and-theoretical-studies-on-mononuclear-complexes-of-eu-iii-with-pyridine-monocarboxylate-n-oxides-in-aqueous-solution
#1
Rama Mohana Rao Dumpala, Neetika Rawat, Anil Boda, Sk Musharaf Ali, B S Tomar
The mononuclear complexes formed by Eu(III) with three isomeric pyridine monocarboxylate-N-oxides namely picolinic acid-N-oxide (PANO), nicotinic acid-N-oxide (NANO) and isonicotinic acid-N-oxide (IANO) in aqueous solutions were studied by potentiometry, luminescence spectroscopy and isothermal titration calorimetry (ITC) to determine the speciation, coordination, luminescence properties and thermodynamic parameters of the complexes formed during the course of the reaction. More stable six membered chelate complexes with stoichiometry (MLi, i=1-4) are formed by Eu(III) with PANO while non chelating ML and ML2 complexes are formed by NANO and IANO...
September 9, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
https://www.readbyqxmd.com/read/28922636/effects-of-mutations-on-active-site-conformation-and-dynamics-of-rna-dependent-rna-polymerase-from-coxsackievirus-b3
#2
Hujun Shen, Mingsen Deng, Yachao Zhang
Recent crystal structures of RNA-dependent RNA polymerase (3D(pol)) from Coxsackievirus B3 (CVB3) revealed that a tyrosine mutation at Phe364 (F364Y) resulted in structures with open active site whereas a hydrophobic mutation at Phe364 (F364A) led to conformations with closed active site. Besides, the crystal structures showed that the F364W mutation had no preference between the open and closed active sites, similar to wild-type. In this paper, we present a molecular dynamics (MD) study on CVB3 3D(pol) in order to address some important questions raised by experiments...
September 12, 2017: Journal of Molecular Graphics & Modelling
https://www.readbyqxmd.com/read/28922604/a-comparative-study-on-the-performance-of-inert-and-functionalized-spheres-coated-with-solid-dispersions-made-of-two-structurally-related-antifungal-drugs
#3
Naila A Mugheirbi, Peter O'Connell, Dolores R Serrano, Anne Marie Healy, Lynne S Taylor, Lidia Tajber
Fluid bed coating offers potential advantages as a formulation platform for amorphous solid dispersions (ASDs) of poorly soluble drugs, being a one-step manufacturing process which could reduce the risk of phase separation associated with multiple step manufacturing approaches. However, the impact of the physicochemical nature of carrier spheres on the properties and drug release from the ASDs has not been studied in detail. In this work, tartaric acid (TAP) and microcrystalline cellulose (CEL) spheres were chosen as examples of functional and inert beads, respectively...
September 18, 2017: Molecular Pharmaceutics
https://www.readbyqxmd.com/read/28922450/structural-insight-into-the-xtacc3-xmap215-interaction-from-cd-and-nmr-studies-on-model-peptides
#4
Angélica Partida-Hanon, Miguel A Treviño, Miguel Mompeán, Ma Ángeles Jiménez, Marta Bruix
TACC3 is a centrosomal adaptor protein that plays important roles during mitotic spindle assembly. It interacts with chTOG/XMAP215, which catalyzes the addition of tubulin dimers during microtubule growth. A 3D coiled-coil model for this interaction is available but the structural details are not well described. To characterize this interaction at atomic resolution, we have designed a simplified version of the system based on small peptides. Four different peptides have been studied by circular dichroism and nuclear magnetic resonance both singly and in all possible combinations; namely, five peptide pairs and two trios...
September 18, 2017: Biopolymers
https://www.readbyqxmd.com/read/28922400/protein-folding-misfolding-and-aggregation-the-importance-of-two-electron-stabilizing-interactions
#5
Andrzej Stanisław Cieplak
Proteins associated with neurodegenerative diseases are highly pleiomorphic and may adopt an all-α-helical fold in one environment, assemble into all-β-sheet or collapse into a coil in another, and rapidly polymerize in yet another one via divergent aggregation pathways that yield broad diversity of aggregates' morphology. A thorough understanding of this behaviour may be necessary to develop a treatment for Alzheimer's and related disorders. Unfortunately, our present comprehension of folding and misfolding is limited for want of a physicochemical theory of protein secondary and tertiary structure...
2017: PloS One
https://www.readbyqxmd.com/read/28921994/anisotropic-cracking-of-nanocrystal-superlattices
#6
Benjamin T Diroll, Xuedan Ma, Yaoting Wu, Christopher B Murray
The synthesis colloidal nanocrystals in non-polar organic solvents has led to exceptional size- and shape-control, enabling the formation of nanocrystal superlattices isostructural to atomic lattices built with nanocrystals rather than atoms. The long aliphatic ligands (e.g. oleic acid) used to achieve this control separate nanocrystals too far in the solid-state for most charge-transporting devices. Solid-state ligand exchange, which brings particles closer together and enhances conductivity, necessitates large changes in the total volume of the solid (compressive stress), which leads to film cracking...
September 18, 2017: Nano Letters
https://www.readbyqxmd.com/read/28921990/disruption-of-asymmetric-lipid-bilayer-models-mimicking-the-outer-membrane-of-gram-negative-bacteria-by-an-active-plasticin
#7
Jean-Philippe Michel, Yingxiong Wang, Irena Kiesel, Yuri Gerelli, Veronique Rosilio
The outer membrane (OM) of Gram-negative bacteria is a complex and asymmetric bilayer that antimicrobial peptides must disrupt in order to provoke the cell lysis. The inner and external leaflets of the OM are mainly composed of phospholipids (PL), and lipopolysaccharide (LPS), respectively. Supported lipid bilayers are interesting model systems to mimic the lipid asymmetric scaffold of the OM and determine the quantitative and mechanistic effect of antimicrobial agents, using complementary physicochemical techniques...
September 18, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28921989/universal-calibration-of-computationally-predicted-n-1s-binding-energies-for-interpretation-of-xps-experimental-measurements
#8
Jing Zhao, Fei Gao, Sidharam Pundlik Pujari, Han Zuilhof, Andrew Teplyakov
Computationally predicted N 1s core level energies are commonly used to interpret the experimental measurements obtained with X-ray photoelectron spectroscopy. This work compares the application of Koopmans' theorem to core electrons using the B3LYP functional with two commonly used basis sets, analyses the factors relevant to the comparison of the computational with experimental data, and presents several correlations that allow an accurate prediction of the N 1s binding energy. The first correlation is obtained with a series of known nitrogen-containing functional groups on well-characterized organic monolayers...
September 18, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28921960/boron-difluoride-adducts-of-a-flexidentate-pyridine-substituted-formazanate-ligand-property-modulation-via-protonation-and-coordination-chemistry
#9
Stephanie M Barbon, Jasmine V Buddingh, Ryan R Maar, Joe B Gilroy
The synthesis and characterization of a flexidentate pyridine-substituted formazanate ligand and its boron difluoride adducts, formed via two different coordination modes of the title ligand, are described. The first adduct adopted a structure that was typical of other boron difluoride adducts of triarylformazanate ligands and contained a free pyridine subsituent, while the second was formed via the chelation of nitrogen atoms from the formazanate backbone and the pyridine substituent. Stepwise protonation of the pydridine-functionalized adduct, which is essentially nonemissive, resulted in a significant increase in the fluorescence quantum yield up to a maximum of 18%, prompting the study of this adduct as a pH sensor...
September 18, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28921884/structural-characterization-and-functional-analysis-of-cystathionine-%C3%AE-synthase-an-enzyme-involved-in-the-reverse-transsulfuration-pathway-of-bacillus-anthracis
#10
Suneeta Devi, Syed Arif Abdul Rehman, Khaja Faisal Tarique, Samudrala Gourinath
The reverse transsulfuration pathway has been reported to produce cysteine from homocysteine in eukaryotes ranging from protozoans to mammals while bacteria and plants produce cysteine via a de-novo pathway. Interestingly, the bacterium Bacillus anthracis includes enzymes of the reverse transsulfuration pathway viz. cystathionine β-synthase (BaCBS, previously annotated to be an O-acetylserine sulfhydrylase (OASS)) and cystathionine γ-lyase. Here, we report the structure of BaCBS at a resolution of 2.2 Å...
September 16, 2017: FEBS Journal
https://www.readbyqxmd.com/read/28921741/chalcogen-atom-annulated-perylene-diimide-trimers-for-highly-efficient-nonfullerene-polymer-solar-cells
#11
Yuwei Duan, Xiaopeng Xu, Ying Li, Zuojia Li, Qiang Peng
This communication reports the synthesis of two novel chalcogen-atom-annulated perylene diimide (PDI) trimers with twisted structures, TriPDI-S and TriPDI-Se, for efficient nonfullerene polymer solar cells. TriPDI-Se exhibits more compact molecular arrangement due to the stronger intermolecular interactions induced by the selenium atom. This selenium annulation endows TriPDI-Se with improved absorption and crystallinity in its blend film. The resulting devices exhibit enhanced Jsc of 17.15 mA cm(-2) and fill factor (FF) of 66...
September 15, 2017: Macromolecular Rapid Communications
https://www.readbyqxmd.com/read/28921684/generation-of-stable-ruthenium-iv-ketimido-complexes-via-oxidative-addition-of-oxime-esters-to-ruthenium-ii-reactivity-studies-based-on-electronic-properties-of-the-ru-n-bond
#12
Takuya Shimbayashi, Kazuhiro Okamoto, Kouichi Ohe
The reaction of an oxime ester with RuX2(PPh3)3 proceeded smoothly at room temperature to afford a stable Ru(IV)-ketimido complex as an oxidative adduct. The structure of the complex was unambiguously determined by X-ray crystallographic analysis, which showed an almost linear Ru-N-C array. The electronic properties of the nitrogen atom were estimated by density functional theory (DFT) calculations, and results suggested the double-bond character of the Ru-N bond. Kinetic studies combined with consideration of the substituent effect on the oxime ester led to proposing the reaction mechanism involving oxidative addition, which could proceed via N,O-chelate coordination to the Ru center prior to N-O bond cleavage...
September 16, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28920669/in-situ-studies-of-solid-electrolyte-interphase-sei-formation-on-crystalline-carbon-surfaces-by-neutron-reflectometry-and-atomic-force-microscopy
#13
Miriam Steinhauer, Michael Stich, Mario Kurniawan, Beatrix-Kamelia Seidlhofer, Marcus Trapp, Andreas Bund, Norbert Wagner, K Andreas Friedrich
The solid electrolyte interphase (SEI) is a complex and fragile passivation layer with crucial importance for the functionality of lithium-ion batteries. Due to its fragility and reactivity, the use of in situ techniques is preferable for the determination of the SEI's true structure and morphology during its formation. In this study, we use in situ neutron reflectometry (NR) and in situ atomic force microscopy (AFM) to investigate the SEI formation on a carbon surface. It was found that a lithium rich adsorption layer is already present at the open circuit voltage on the carbon sample surface and that the first decomposition products start to deposit close to this potential...
September 18, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28920607/tuning-the-electronic-environment-of-zinc-ions-with-a-ligand-for-dendrite-free-zinc-deposition-in-an-ionic-liquid
#14
Zhen Liu, Guozhu Li, Tong Cui, Abhishek Lahiri, Andriy Borodin, Frank Endres
In this work, we report on the influence of an organic ligand on the electrodeposition of Zn from an ionic liquid (IL) electrolyte. Zinc oxide was first dissolved in a protic IL. By introducing a 2-methylimidazole (2-MIm) ligand, the electronic environment of zinc ions, Zn(ii) complexes and the structure of the IL are considerably altered, as verified by both X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. Due to the electron donation effect of the ligand, the zinc ions become less positively charged and exhibit a lower binding energy by -0...
September 18, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28920598/interaction-between-h2o-n2-co-no-no2-and-n2o-molecules-and-a-defective-wse2-monolayer
#15
Dongwei Ma, Benyuan Ma, Zhiwen Lu, Chaozheng He, Yanan Tang, Zhansheng Lu, Zongxian Yang
In this study, the interaction between gas molecules, including H2O, N2, CO, NO, NO2 and N2O, and a WSe2 monolayer containing an Se vacancy (denoted as VSe) has been theoretically studied. Theoretical results show that H2O and N2 molecules are highly prone to be physisorbed on the VSe surface. The presence of the Se vacancy can significantly enhance the sensing ability of the WSe2 monolayer toward H2O and N2 molecules. In contrast, CO and NO molecules highly prefer to be molecularly chemisorbed on the VSe surface with the non-oxygen atom occupying the Se vacancy site...
September 18, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28920434/ultralow-temperature-solution-processed-aluminum-oxide-dielectrics-via-local-structure-control-of-nanoclusters
#16
Jeong-Wan Jo, Yong-Hoon Kim, Joohyung Park, Jae Sang Heo, Seongpil Hwang, Won-June Lee, Myung-Han Yoon, Myung-Gil Kim, Sung Kyu Park
Oxide dielectric materials play a key role in a wide range of high-performance solid-state electronics from semiconductor devices to emerging wearable and soft bio-electronic devices. Although lots of previous advances are noteworthy, their typical processing temperature still far exceeds the thermal limitations of soft materials, impeding their wide utilization in these emerging fields. Here, we report an innovative route to form highly reliable aluminum-oxide dielectric films using an ultralow temperature (< 60 ˚C) solution process with a class of oxide nanocluster precursors...
September 18, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28920424/nanotubular-iridium-cobalt-mixed-oxide-crystalline-architectures-inherited-from-cobalt-oxide-for-highly-efficient-oxygen-evolution-reaction-catalysis
#17
Areum Yu, Chongmok Lee, Myung Hwa Kim, Youngmi Lee
We report the unique transformation of one-dimensional tubular mixed oxide nanocomposites of iridium (Ir) and cobalt (Co) denoted as IrxCo1-xOy, where x is the relative Ir atomic content to the overall metal content. The formation of a variety of IrxCo1-xOy (0 ≤ x ≤ 1) crystalline tubular nanocomposites was readily achieved by electrospinning and subsequent calcination process. Structural characterizations clearly confirmed that IrxCo1-xOy polycrystalline nanocomposites had a tubular morphology consisting of Ir/IrO2 and Co3O4; and Ir, Co and O were homogeneously distributed throughout the entire nanostructures...
September 18, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28919740/low-toxic-maghemite-nanoparticles-for-theranostic-applications
#18
Elena A Kuchma, Peter V Zolotukhin, Anna A Belanova, Mikhail A Soldatov, Tatiana A Lastovina, Stanislav P Kubrin, Anatoliy V Nikolsky, Lidia I Mirmikova, Alexander V Soldatov
BACKGROUND: Iron oxide nanoparticles have numerous and versatile biological properties, ranging from direct and immediate biochemical effects to prolonged influences on tissues. Most applications have strict requirements with respect to the chemical and physical properties of such agents. Therefore, developing rational design methods of synthesis of iron oxide nanoparticles remains of vital importance in nanobiomedicine. METHODS: Low toxic superparamagnetic iron oxide nanoparticles (SPIONs) for theranostic applications in oncology having spherical shape and maghemite structure were produced using the fast microwave synthesis technique and were fully characterized by several complementary methods (transmission electron microscopy [TEM], X-ray diffraction [XRD], dynamic light scattering [DLS], X-ray photoelectron spectroscopy [XPS], X-ray absorption near edge structure [XANES], Mossbauer spectroscopy, and HeLa cells toxicity testing)...
2017: International Journal of Nanomedicine
https://www.readbyqxmd.com/read/28919442/structural-and-functional-analysis-of-the-c-terminal-region-of-flig-an-essential-motor-component-of-vibrio-na-driven-flagella
#19
Yohei Miyanoiri, Atsushi Hijikata, Yuuki Nishino, Mizuki Gohara, Yasuhiro Onoue, Seiji Kojima, Chojiro Kojima, Tsuyoshi Shirai, Masatsune Kainosho, Michio Homma
The flagellar motor protein complex consists of rotor and stator proteins. Their interaction generates torque of flagellum, which rotates bidirectionally, clockwise (CW) and counterclockwise. FliG, one of the rotor proteins, consists of three domains: N-terminal (FliGN), middle (FliGM), and C-terminal (FliGC). We have identified point mutations in FliGC from Vibrio alginolyticus, which affect the flagellar motility. To understand the molecular mechanisms, we explored the structural and dynamic properties of FliGC from both wild-type and motility-defective mutants...
September 6, 2017: Structure
https://www.readbyqxmd.com/read/28919419/binding-mode-of-metal-ions-to-the-bacterial-iron-import-protein-efeo
#20
Kanate Temtrirath, Kenji Okumura, Yukie Maruyama, Bunzo Mikami, Kousaku Murata, Wataru Hashimoto
The tripartite EfeUOB system functions as a low pH iron importer in Gram-negative bacteria. In the alginate-assimilating bacterium Sphingomonas sp. strain A1, an additional EfeO-like protein (Algp7) is encoded downstream of the efeUOB operon. Here we show the metal binding mode of Algp7, which carries a M_75 metallopeptidase motif. The Algp7 protein was purified from recombinant E. coli cells and was subsequently characterized using differential scanning fluorimetry, fluorescence spectrometry, atomic absorption spectroscopy, and X-ray crystallography...
September 14, 2017: Biochemical and Biophysical Research Communications
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