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https://www.readbyqxmd.com/read/28437947/hard-x-ray-scanning-imaging-achieved-with-bonded-multilayer-laue-lenses
#1
Xiaojing Huang, Weihe Xu, Evgeny Nazaretski, Nathalie Bouet, Juan Zhou, Yong S Chu, Hanfei Yan
We report scanning hard x-ray imaging with a monolithic focusing optic consisting of two multilayer Laue lenses (MLLs) bonded together. With optics pre-characterization and accurate control of the bonding process, we show that a common focal plane for both MLLs can be realized at 9.317 keV. Using bonded MLLs, we obtained a scanning transmission image of a star test pattern with a resolution of 50 × 50 nm<sup>2</sup>. By applying a ptychography algorithm, we obtained a probe size of 17 × 38 nm<sup>2</sup> and an object image with a resolution of 13 × 13 nm<sup>2</sup>...
April 17, 2017: Optics Express
https://www.readbyqxmd.com/read/28437744/fe-%C3%A2-ions-enhanced-catalytic-properties-of-bio-2co3-nanowires-and-mechanism-study-for-complete-degradation-of-xanthate
#2
Yujiao Guo, Kuixin Cui, Mingyi Hu, Shengming Jin
The wire-like Fe(3+)-doped (BiO)2CO3 photocatalyst was synthesized by a hydrothermal method. The photocatalytic property of Fe(3+)-doped (BiO)2CO3 nanowires was evaluated through degradation of sodium isopropyl xanthate under UV-visible light irradiation. The as-prepared Fe(3+)-doped (BiO)2CO3 nanowires were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), UV-visible diffuse reflectance spectroscopy (UV-vis DRS), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) in detail...
April 17, 2017: Chemosphere
https://www.readbyqxmd.com/read/28437706/three-phases-in-ph-dependent-heme-abstraction-from-myoglobin
#3
Sohini Mukherjee, Manjistha Mukherjee, Sabyasachi Bandyopadhyay, Abhishek Dey
The extent of heme extraction from myoglobin (Mb) by methylethyl ketone is found to be pH dependent and show three distinct phases. Parallel investigations of the protein using resonance Raman (rR) and circular dichroism (CD) across these pH regions indicate that these phases correspond to three different protonation steps in holoMb as the pH of the solution changed. The first transition occurs between pH5-6 and is due to the protonation of one of the heme propionate groups which disrupts its H-bonding with Arg 45 in the loop...
April 9, 2017: Journal of Inorganic Biochemistry
https://www.readbyqxmd.com/read/28437697/catalytic-polymer-clay-composite-for-enhanced-removal-and-degradation-of-diazinon
#4
Itamar A Shabtai, Yael G Mishael
It is well established that organophosphate pesticides, such as diazinon, pose environmental and health risks. Diazinon is prone to rapid acidic hydrolysis, forming the less toxic compound 2-isopropyl-6-methyl-4-pyrimidinol (IMP). In this study, diazinon surface catalyzed hydrolysis was achieved by its adsorption to a composite, based on protonated poly (4-vinyl-pyridine-co-styrene) (HPVPcoS) and montmorillonite (MMT) clay. The adsorption affinity and kinetics of diazinon to HPVPcoS-MMT were significantly higher than those obtained to the deprotonated PVPcoS-MMT, emphasizing the importance of hydrogen bonding...
April 6, 2017: Journal of Hazardous Materials
https://www.readbyqxmd.com/read/28437687/use-of-tourmaline-as-a-potential-petrogenetic-indicator-in-the-determination-of-host-magma-crs-xrd-and-ped-xrf-methods
#5
Bahattin Gullu, Yusuf Kagan Kadioglu
Tourmaline defines a group of complex borosilicate forms as accessory mineral in igneous and metamorphic rocks and they act an important role in the interpretation of the chemical composition changes of the composition of the host fluid of the magma. The variety of tourmaline can be identified by using optical microscopy, X-Ray Diffraction (XRD) and by determining its chemical composition through Polarized Energy Dispersive X-Ray Fluorescence (PED-XRF) methods. However, microscopic investigations and XRD analyses are not quite adequate for detailed determination of tourmaline sub-groups...
April 19, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
https://www.readbyqxmd.com/read/28437681/predicting-wellbeing-among-people-with-epilepsy-using-illness-cognitions
#6
Kirstie A Salter, Kirsty N Prior, Malcolm J Bond
OBJECTIVE: This study sought to examine the synergistic contribution of illness-related perceptions (stigma, severity, and threat) and illness behavior to wellbeing among people with epilepsy. Poorer wellbeing was expected among those who perceived greater stigma, illness severity, and threat and had more extreme illness behavior. METHODS: Individuals with a diagnosis of epilepsy (N=210), recruited through local and online support groups, completed a questionnaire comprising demographic and epilepsy-specific information, and validated measures of illness perceptions and behavior, epilepsy-related quality of life, and general psychological health...
April 21, 2017: Epilepsy & Behavior: E&B
https://www.readbyqxmd.com/read/28437617/electrostatic-origin-of-red-solvatochromic-shift-of-dfhbdi-in-rna-spinach
#7
Samik Bose, Suman Chakrabarty, Debashree Ghosh
Interactions with environment tune the spectral properties of biological chromophores, e.g. fluorescent proteins. Understanding of the relative contribution of the various types of non-covalent interactions in the spectral shifts can provide rational design principles towards developing new fluorescent probes. In this work, we investigate the origin of the red-shift in the absorption spectra of difluoro hydroxybenzylidene dimethyl imidazolinone (DFHBDI) chromophore in RNA Spinach as compared to the aqueous solution...
April 24, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28437611/dynamical-insights-in-the-decomposition-of-1-2-dioxetane
#8
Morgane Vacher, Anders M Brakestad, Hans O Karlsson, Ignacio Fdez Galván, Roland Lindh
Chemiluminescence in 1,2-dioxetane occurs via a thermally-activated decomposition reaction into two formaldehyde molecules. Both ground state and non-adiabatic dynamics (including singlet excited states) of the decomposition reaction have been simulated, starting from the first O-O bond breaking transition structure. The ground state dissociation occurs between t=30 fs and t=140 fs. The so-called entropic trap leads to frustrated dissociations, postponing the decomposition reaction. Specific geometrical conditions are necessary for the trajectories to escape from the entropic trap and for dissociation to be possible...
April 24, 2017: Journal of Chemical Theory and Computation
https://www.readbyqxmd.com/read/28437597/weight-loss-in-weight-watchers-online-with-and-without-an-activity-tracking-device-compared-to-control-a-randomized-trial
#9
J Graham Thomas, Hollie A Raynor, Dale S Bond, Anna K Luke, Chelsi C Cardoso, Gary D Foster, Rena R Wing
OBJECTIVE: To evaluate a commercial online weight loss program and activity tracker, which are popular but have unknown efficacy. METHODS: Two hundred seventy-nine participants with BMI 27 to 40 kg/m(2) were randomized to 12 months of the Weight Watchers Online program alone (WWO) or with the ActiveLink(®) activity tracking device (WWO+AL) or an online newsletter (Control). RESULTS: Weight losses at 3 months were significantly greater in WWO (2...
April 24, 2017: Obesity
https://www.readbyqxmd.com/read/28437119/synthesis-of-naphthoquinolizinones-through-rh-iii-catalyzed-double-c-sp-2-h-bond-carbenoid-insertion-and-annulation-of-2-aryl-3-cyanopyridines-with-%C3%AE-diazo-carbonyl-compounds
#10
Beibei Zhang, Bin Li, Xinying Zhang, Xuesen Fan
An unprecedented Rh(III)-catalyzed double C(sp(2))-H bond carbenoid insertion and annulation of 2-aryl-3-cyanopyridines with α-diazo carbonyl compounds is presented. Through this cascade reaction, a series of naphthoquinolizinone derivatives with a large π-system were efficiently prepared. The reactions could selectively afford naphthoquinolizinones with either an amine or an amide unit attached on the 11-position depending on the nature of the solvent and the additive used. Compared with literature methods, this is a more efficient, convenient, and atom-economic way to provide polycyclic heteroaromatic compounds through direct π-extension of simple aromatics via inert C-H bond activation and functionalization...
April 24, 2017: Organic Letters
https://www.readbyqxmd.com/read/28437118/blue-light-photocatalytic-glycosylation-without-electrophilic-additives
#11
Peng Wen, David Crich
Photocatalytic formation of glycosidic bonds employing stable and readily accessible O-glycosyl derivatives of 2,2,6,6-tetramethylpiperidin-1-ol is presented that employs an iridium-based photocatalyst and blue LEDs. The reaction proceeds at room temperature and in the absence of additives other than 4 Å molecular sieves. Stereoselectivities are modest but nevertheless dependent on the anomeric configuration of the donor, suggesting a substantial degree of concerted character.
April 24, 2017: Organic Letters
https://www.readbyqxmd.com/read/28437102/insights-into-the-complex-photophysics-and-photochemistry-of-the-simplest-nitroaromatic-compound-a-caspt2-casscf-study-on-nitrobenzene
#12
Angelo Giussani, Graham A Worth
Nitrobenzene is the simplest nitroaromatic compound and yet is characterized by a challenging and rich photophysics and photochemistry. In the present contribution the main decay paths undertaken by the system after UV absorption from both the brightest 1(La*) and the lowest 1(nA*) singlet excited states have been characterized by means of CASPT2//CASSCF computations. The obtained results match with the main photophysical properties experimentally reported: the lack of fluorescence and phosphorescence emission is justified by the presence of accessible conical intersections and intersystem crossing regions between respectively the 1(nA*) and 3(nA*) states with the ground state, while the high triplet quantum yield is attributable to the strong coupling between the 1(nA*) and 3(O*) states along the main decay path of the former...
April 24, 2017: Journal of Chemical Theory and Computation
https://www.readbyqxmd.com/read/28437101/ground-state-and-excited-state-tuning-in-ferric-dipyrrin-complexes-promoted-by-ancillary-ligand-exchange
#13
Claudia Kleinlein, Shao-Liang Zheng, Theodore A Betley
Three ferric dipyrromethene complexes featuring different ancillary ligands were synthesized by one electron oxidation of ferrous precursors. Four-coordinate iron complexes of the type ((Ar)L)FeX2 [(Ar)L = 1,9-(2,4,6-Ph3C6H2)2-5-mesityldipyrromethene] with X = Cl or (t)BuO were prepared and found to be high-spin (S = (5)/2), as determined by superconducting quantum interference device magnetometry, electron paramagnetic resonance, and (57)Fe Mössbauer spectroscopy. The ancillary ligand substitution was found to affect both ground state and excited properties of the ferric complexes examined...
April 24, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28437089/%C3%AF-n-c-bond-difunctionalization-in-bridged-twisted-amides-sew-and-cut-activation-approach-to-functionalized-isoquinolines
#14
Feng Hu, Pradeep Nareddy, Roger Lalancette, Frank Jordan, Michal Szostak
A rare example of highly selective σ N-C bond difunctionalization in bridged twisted lactams through N-C cleavage has been achieved. In combination with the intramolecular Heck cyclization, this method affords a two-step bond reorganization event ("sew-and-cut") to access functionalized isoquinoline ring systems directly with high atom economy. C-H bond functionalizations directed by a weakly coordinating bridged amide bond increase scaffold diversity. Preliminary mechanistic studies on the effect of amide distortion and the role of electrophile in this unusual σ N-C amide difunctionalization are described...
April 24, 2017: Organic Letters
https://www.readbyqxmd.com/read/28437085/a-short-covalent-synthesis-of-an-all-carbon-ring-2-rotaxane
#15
Luuk Steemers, Martin J Wanner, Andreas W Ehlers, Henk Hiemstra, Jan H van Maarseveen
While the current supramolecular syntheses of [2]rotaxanes are generally efficient, the final product always retains the functional groups required for non-covalent preorganization. A short and high-yielding covalent-template-assisted approach is reported for the synthesis of a [2]rotaxane. A terephthalic acid template core preorganizes the covalently connected ring precursor fragments to induce a clipping-type cyclization over the thread moiety. Cleavage of the temporary ester bonds that connect the ring and thread fragments liberates the [2]rotaxane...
April 24, 2017: Organic Letters
https://www.readbyqxmd.com/read/28437083/dual-plug-and-display-synthetic-assembly-using-orthogonal-reactive-proteins-for-twin-antigen-immunization
#16
Karl Brune, Can Buldun, Yuanyuan Li, Iona Taylor, Florian Brod, Sumi Biswas, Mark Howarth
Engineering modular platforms to control biomolecular architecture can advance both the understanding and manipulation of biological systems. Icosahedral particles uniformly displaying single antigens stimulate potent immune activation and have been successful in various licensed vaccines. However, it remains challenging to display multiple antigens on a single particle, to induce broader immunity protective across strains or even against distinct diseases. Here we design a dually-addressable synthetic nanoparticle, by engineering the multimerizing coiled-coil IMX313 and two orthogonally-reactive split proteins...
April 24, 2017: Bioconjugate Chemistry
https://www.readbyqxmd.com/read/28437068/observing-the-overgrowth-of-a-second-metal-on-silver-cubic-seeds-in-solution-by-surface-enhanced-raman-scattering
#17
Yun Zhang, Jingyue Liu, Jaewan Ahn, Ting-Hui Xiao, Zhi-Yuan Li, Dong Qin
We report the development of an isocyanide-based molecular probe for in situ characterizing the overgrowth of a second metal on silver nanocrystal seeds in solution by surface-enhanced Raman scattering (SERS). As the first demonstration, we elucidate that the vibrational frequency of 2,6-dimethylphenyl isocyanide (2,6-DMPI) can serve as a distinctive reporter for capturing the nucleation of Pt on the edges of Ag nanocubes in the aqueous solution containing a Pt precursor, ascorbic acid, and poly(vinylpyrrolidone) under ambient condition...
April 24, 2017: ACS Nano
https://www.readbyqxmd.com/read/28437066/electric-field-driven-direct-desulfurization
#18
Bogdana Borca, Tomasz Michnowicz, Rémi Pétuya, Marcel Pristl, Verena Schendel, Ivan Pentegov, Ulrike Kraft, Hagen Klauk, Peter Wahl, Rico Gutzler, Andrés Arnau, Uta Schlickum, Klaus Kern
The ability to elucidate the elementary steps of a chemical reaction at the atomic scale is important for the detailed understanding of the processes involved which is key to uncover avenues for improved reaction paths. Here, we track the chemical pathway of an irreversible direct desulfurization reaction of tetracenothiophene adsorbed on the Cu(111) closed-packed surface at the submolecular level. Using the precise control of the tip position in a Scanning Tunneling Microscope and the electric field applied across the tunnel junction, the two carbon-sulfur bonds of a thiophene unit are successively cleaved...
April 24, 2017: ACS Nano
https://www.readbyqxmd.com/read/28437027/reprogrammable-assembly-of-molecular-motor-on-solid-surfaces-via-dynamic-bonds
#19
Li Yu, Jian Sun, Qian Wang, Yan Guan, Le Zhou, Jingxuan Zhang, Lanying Zhang, Huai Yang
Controllable assembly of molecular motors on solid surfaces is a fundamental issue for providing them to perform physical tasks. However, it can hardly be achieved by most previous methods due to their inherent limitations. Here, a general strategy is designed for the reprogrammable assembly of molecular motors on solid surfaces based on dynamic bonds. In this method, molecular motors with disulfide bonds can be remotely, reversibly, and precisely attached to solid surfaces with disulfide bonds, regardless of their chemical composition and microstructure...
April 24, 2017: Small
https://www.readbyqxmd.com/read/28436822/distinguishing-homogeneous-heterogeneous-degradation-of-norfloxacin-in-a-photochemical-fenton-like-system-fe3o4-uv-oxalate-and-the-interfacial-reaction-mechanism
#20
Mingjie Huang, Tao Zhou, Xiaohui Wu, Juan Mao
This study demonstrated the efficient degradation of a typical bio-refractory antibiotic norfloxacin (NOR) in a photochemical iron oxides/oxalate system adopting magnetic catalyst (Fe3O4/UV/Ox). It was found that the in-situ generated HO was the main reactive oxygen species (ROS) but CO2(-) could also participate in the NOR degradation to form formylate organic intermediates. Besides, NOR would be degraded via an interesting pathway comprising an initial lag and a subsequent rapid period, where the former could be eliminated by introducing the pre-dissolution of Fe3O4 particles...
March 6, 2017: Water Research
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