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Journal of Physical Chemistry Letters

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https://www.readbyqxmd.com/read/27936328/segmental-deuteration-of-%C3%AE-synuclein-for-neutron-reflectometry-on-tethered-bilayers
#1
Zhiping Jiang, Frank Heinrich, Ryan P McGlinchey, James M Gruschus, Jennifer C Lee
Neutron reflectometry (NR) is uniquely suited for studying protein interaction with phospholipid bilayers along the bilayer normal on an angstrom scale. However, NR on its own cannot discern specific membrane-bound regions due to a lack of scattering contrast within a protein. Here we report the successful coupling of native chemical ligation (NCL) and NR to study α-synuclein (α-syn), a membrane-binding neuronal protein central in Parkinson's disease. Two α-syn variants were generated where either the first 86 or last 54 residues are deuterated, allowing for region-specific contrast within the protein and the identification of membrane interacting residues by NR...
December 9, 2016: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/27936321/stability-of-a-transient-protein-complex-in-a-charged-aqueous-droplet-with-variable-ph
#2
Myong In Oh, Styliani Consta
Electrospray ionization mass spectrometry (ESI-MS) has the potential to become a high-throughput robust experimental method for the detection of protein-protein equilibrium constants. Poorly understood processes that affect the stability of weak non-covalent protein complexes in the intervening droplet environment is a significant factor that precludes the advancement of the method. We use molecular dynamics to study the stability of a ubiquitin and ubiquitin-associated domain complex (RCSB PDB code 2MRO) in an aqueous droplet with changing size and charge concentration...
December 9, 2016: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/27935718/emergence-of-solvent-separated-na-cl-ion-pair-in-salt-water-photoelectron-spectroscopy-and-theoretical-calculations
#3
Gao-Lei Hou, Cheng-Wen Liu, Ren-Zhong Li, Hong-Guang Xu, Yi Qin Gao, Wei-Jun Zheng
Solvation of salts in water is a fundamental physical chemical process, but the underlying mechanism remains unclear. We investigated the contact ion pair (CIP) to solvent-separated ion pair (SSIP) transition in NaCl(H2O)n clusters with anion photoelectron spectroscopy and ab initio calculations. It is found that the SSIP type of structures show up at n = 2 for NaCl(-)(H2O)n anions. For neutral NaCl(H2O)n, the CIP structures are dominant at n < 9. At n = 9-12, the CIP structures and SSIP structures of NaCl(H2O)n are nearly degenerate in energy, coincident to the H2O:NaCl molar ratio of NaCl saturated solution and implying that the CIP and SSIP structures can coexist in concentrated solutions...
December 9, 2016: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/27935717/the-role-of-unconventional-hydrogen-bonds-in-determining-bii-propensities-in-b-dna
#4
Alexandra Balaceanu, Marco Pasi, Pablo D Dans, Adam Hospital, Richard Lavery, Modesto Orozco
An accurate understanding of DNA backbone transitions is likely to be the key for elucidating the puzzle of the intricate sequence-dependent mechanical properties that govern most of the biologically relevant functions of the double helix. One factor believed to be important in indirect recognition within protein-DNA complexes is the combined effect of two DNA backbone torsions (ε and ζ) which give rise to the well-known BI/BII conformational equilibrium. In this work we explain the sequence-dependent BII propensity observed in RpY steps (R = purine; Y = pyrimidine) at the tetranucleotide level with the help of a previously undetected C-H···O contact between atoms belonging to adjacent bases...
December 9, 2016: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/27935313/on-the-energy-ordering-of-molecular-orbitals
#5
Peter Puschnig, A Daniel Boese, Martin Willenbockel, Marcel Meyer, Daniel Lüftner, Eva Maria Reinisch, Thomas Ules, Georg Koller, Serguei Soubatch, Michael G Ramsey, Frank Stefan Tautz
Orbitals are invaluable in providing a model of bonding in molecules or between molecules and surfaces. Most present-day methods in computational chemistry begin by calculating the molecular orbitals of the system. To what extent have these mathematical objects analogues in the real world? To shed light on this intriguing question, we employ a photoemission tomography study on monolayers of 3,4,9,10-perylene-tetracarboxylic acid dianhydride (PTCDA) grown on three Ag surfaces. The characteristic photoelectron angular distribution enables us to assign individual molecular orbitals to the emission features...
December 9, 2016: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/27809540/chemisorption-of-hydroxide-on-2d-materials-from-dft-calculations-graphene-versus-hexagonal-boron-nitride
#6
Benoit Grosjean, Clarisse Péan, Alessandro Siria, Lyderic Bocquet, Rodolphe Vuilleumier, Marie-Laure Bocquet
Recent nanofluidic measurements revealed strongly different surface charge mea- surements for boron-nitride and graphitic nanotubes when in contact with saline and alkaline water.1,2 These observations contrast with the similar reactivity of a graphene layer and its boron nitride counterpart, using Density Functional Theory (DFT) frame- work, for intact and dissociative adsorption of gaseous water molecules. Here, we in- vestigate by DFT in implicit water single and multiple adsorption of anionic hydroxide on single layers...
November 3, 2016: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/27809539/excimers-in-the-lowest-rotational-quantum-state-in-liquid-helium
#7
Luis Guillermo Mendoza-Luna, Nagham M K Shiltagh, Mark J Watkins, Nelly Bonifaci, Frederic Aitken, Klaus von Haeften
Evidence for helium excimers (He∗_2) in the lowest allowed rotational quantum state in liquid helium is presented. He∗_2 was generated by a corona discharge in the gas and normal liquid phases. Fluorescence spectra recorded in the visible region between 3.8 and 5.0 K and 0.2 and 5.6 bar showed the rotationally resolved d3 Σ+ u → b3 Πg transition of He∗_2. Analysis of the pressure and temperature dependence of lineshifts and line intensities showed features of solvated He∗_2 superimposed on its gas phase spectrum and, in the liquid phase only, pressure-induced rotational cooling...
November 3, 2016: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/27809535/charged-particle-imaging-of-the-deprotonated-octatrienoic-acid-anion-evidence-for-a-photo-induced-cyclization-reaction
#8
Christopher W West, James N Bull, Jan R R Verlet
The photoelectron spectroscopy of the deprotonated octatrienoic acid anion, [C7H9-CO2](-), shows the formation of [C7H9](-) and loss of H(-) at hν = 4.13 eV. Using velocity map imaging, the H(-) fragment was characterized to have a Boltzmann-like kinetic energy distribution consistent with dissociation on a ground electronic state. Similar dynamics were not observed at hν = 4.66 eV even though there is clear evidence for recovery of the ground electronic state of [C7H9-CO2](-). In accord with supporting electronic structure calculations, the production of H(-) at hν = 4...
November 3, 2016: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/27804296/influence-of-perovskite-morphology-on-slow-and-fast-charge-transport-and-hysteresis-in-the-perovskite-solar-cells
#9
Nasim Mohammadian, Ahmad Moshaii, Amirhossein Alizadeh, Saba Gharibzadeh, Raheleh Mohammadpour
We have investigated the influence of perovskite morphology on slow and fast charge transport in the perovskite solar cells. Solar cells with different perovskite cuboid sizes (50-300 nm) have been fabricated using various methylammonium iodide concentrations. Both the low-frequency capacitance and hysteresis are maximum for the cell with the largest perovskite grains (300 nm). The low-frequency capacitance is about three orders of magnitude greater than the intermediate frequency capacitance, indicating the great role of ions on the slow responses and hysteresis...
November 3, 2016: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/27797214/analysis-of-the-hysteresis-behavior-of-perovskite-solar-cells-with-interfacial-fullerene-self-assembled-monolayers
#10
Marta Valles-Pelarda, Bruno Clasen Hames, Inés García-Benito, Osbel Almora, Agustin Molina-Ontoria, Rafael S Sánchez, Germà Garcia-Belmonte, Nazario Martín, Ivan Mora-Sero
The use of self-assembled monolayers (SAMs) of fullerene derivatives reduces the hysteresis of perovskite solar cells (PSCs). We have investigated three different fullerene derivatives observing a decrease on hysteresis for all the cases. Several processes can contribute to the hysteresis behavior on PSCs. We have determined that the reduced hysteresis observed for devices with SAMs is produced by a decrease of the capacitive hysteresis. In addition, with an appropriated functionalization, SAMs can increase photocurrent even when no electron selective contact (ESC) is present and a SAM is deposited just on top of the transparent conductive oxide...
November 3, 2016: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/27758105/bright-perovskite-nanocrystal-films-for-efficient-light-emitting-devices
#11
Xiaoyu Zhang, Chun Sun, Yu Zhang, Hua Wu, Changyin Ji, Yahui Chuai, Peng Wang, Shanpeng Wen, Chunfeng Zhang, William W Yu
The high photoluminescence efficiency, high color purity, and easy tunable bandgap make inorganic perovskite nanocrystals very attractive in luminescent display applications. Here, we report a color-saturated, red light-emitting diode (LED) using an inverted organic/inorganic hybrid structure and perovskite nanocrystals. We demonstrated that through a simple post treatment to the perovskite nanocrystals with polyethylenimine, the surface defects of the perovskite nanocrystals could be well passivated, leading to great enhancements on their absolute photoluminescence quantum yield and photoluminescence lifetime...
November 3, 2016: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/27806576/very-large-pi-conjugation-despite-strong-non-planarity-a-path-for-designing-new-semiconducting-polymers
#12
Alessandro Troisi, Alex Shaw
When two pi-conjugated fragments are connected by a bond between two sp2 carbon atoms, a torsion around this bond is expected to break the overall pi-conjugation. We show that for specially selected monomers the pi-conjugation is insensitive to torsions around a C-C bonds up to about 60 degrees. We provide a number of examples for this very unexpected phenomenon and a simple explanation. We propose that this feature can be incorporated into conjugated polymers to generate semiconducting materials that are extremely insensitive to structural disorder...
November 2, 2016: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/27806567/anisotropic-tuning-on-graphite-thermal-conductivity-by-lithium-intercalation
#13
Xin Qian, Xiaokun Gu, Mildred S Dresselhaus, Ronggui Yang
Understanding thermal transport in lithium-intercalated layered materials is not only important for understanding heat generation and dissipation in lithium ion batteries, but also potentially provides a novel way to design materials with reversibly tunable thermal conductivity. In this work, the thermal conductivity of lithium-graphite intercalation compounds (LixC6) is calculated using the molecular dynamics simulations, as a function of the amount of lithium intercalated. We found that intercalation of lithium has an anisotropic effect on tuning the thermal conductivity: the thermal conductivity in the basal plane decreases monotonically from 1232 W/m·K of pure graphite to 440 W/m·K of the fully lithiated LiC6, while the thermal conductivity along the c-axis decreases first from 6...
November 2, 2016: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/27804302/unexpected-cation-dynamics-in-the-low-temperature-phase-of-methylammonium-lead-iodide-the-need-for-improved-models
#14
Kacper Drużbicki, Roberto Simone Pinna, Svemir Rudic, Marek Jura, Giuseppe Gorini, Felix Fernandez-Alonso
High-resolution inelastic neutron scattering and extensive first-principles calculations have been used to explore the low-temperature phase of the hybrid solar-cell material me-thylammonium lead iodide up to the well-known phase transition to the tetragonal phase at ca. 160 K. Contrary to original expectation, we find that the Pnma structure for this phase can only provide a qualitative description of the geometry and underlying motions of the organic cation. A substantial lowering of the local symmetry inside the perovskite cage leads to an improved atomis-tic model that can account for all available spectroscopic and thermodynamic data, both at low temperatures and in the vicinity of the aforementioned phase transition...
November 2, 2016: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/27804301/correction-to-torsional-dynamics-and-intramolecular-charge-transfer-in-the-s2-1-1-bu-excited-state-of-peridinin-a-mechanism-for-enhanced-mid-visible-light-harvesting
#15
Soumen Ghosh, Jerome D Roscioli, Michael M Bishop, Jason K Gurchiek, Amy M LaFountain, Harry A Frank, Warren F Beck
No abstract text is available yet for this article.
November 2, 2016: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/27804299/dynamics-of-strong-coupling-between-cdse-quantum-dots-and-surface-plasmon-polaritons-in-subwavelength-holes-array
#16
Hai Wang, Hai-Yu Wang, Andrea Toma, Taka-Aki Yano, Qi-Dai Chen, Huailiang Xu, Hong-Bo Sun, Remo Proietti Zaccaria
We have investigated the strong coupling interaction between excitons of CdSe quantum dots (QDs) and surface plasmon polaritons (SPPs) of gold nanoholes array by steady-state spectroscopic method and transient absorption measurements. Numerical and experimental steady-state measurements demonstrate that the SPPs-QDs system can indeed undergo strong coupling, characterized by a Rabi splitting up to 220 meV. In particular, it is found that in the transient absorption spectra, under resonant excitation, the 1S transition bleaching band from uncoupled CdSe QDs is completely separated into two distinctive bleaching bands, remarkably fingerprinting the hybrid SPPs-QDs state...
November 2, 2016: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/27797213/both-inter-and-intramolecular-coupling-of-o-h-groups-determine-the-vibrational-response-of-the-water-air-interface
#17
Jan Schaefer, Ellen H G Backus, Yuki Nagata, Mischa Bonn
Vibrational coupling is relevant not only for dissipation of excess energy after chemical reactions but also for elucidating molecular structure and dynamics. It is particularly important for O-H stretch vibrational spectra of water, for which it is known that in bulk both intra- and intermolecular coupling alter the intensity and line shape of the spectra. In contrast with bulk, the unified picture of the inter/intra-molecular coupling of O-H groups at the water-air interface has been lacking. Here, combining sum-frequency generation experiments and simulation for isotopically diluted water and alcohols, we unveil effects of inter- and intramolecular coupling on the vibrational spectra of interfacial water...
November 2, 2016: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/27791378/what-can-we-learn-about-cholesterol-s-transmembrane-distribution-based-on-cholesterol-induced-changes-in-membrane-dipole-potential
#18
Stanislav G Falkovich, Hector Martinez-Seara, Alexey M Nesterenko, Ilpo Vattulainen, Andrey A Gurtovenko
Cholesterol is abundant in the plasma membranes of animal cells and is known to regulate a variety of membrane properties. Despite decades of research, the transmembrane distribution of cholesterol is still a matter of debate. Here we consider this outstanding issue through atomistic simulations of asymmetric lipid membranes, whose composition is largely consistent with eukaryotic plasma membranes. We show that the membrane dipole potential changes in a cholesterol-dependent manner. Remarkably, moving cholesterol from the extracellular to the cytosolic leaflet increases the dipole potential on the cytosolic side, and vice versa...
November 2, 2016: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/27802054/surface-enhanced-femtosecond-stimulated-raman-spectroscopy-at-1-mhz-repetition-rates
#19
Lauren Elizabeth Buchanan, Natalie L Gruenke, Michael O McAnally, Bogdan Negru, Hannah E Mayhew, Vartkess Ara Apkarian, George C Schatz, Richard P Van Duyne
Surface-enhanced femtosecond stimulated Raman spectroscopy (SE-FSRS) is an ultrafast Raman technique that combines the sensitivity of surface-enhanced Raman scattering with the temporal resolution of femtosecond stimulated Raman spectroscopy (FSRS). Here, we present the first successful implementation of SE-FSRS using a 1 MHz amplified femtosecond laser system. We compare SE-FSRS and FSRS spectra measured at 1 MHz and 100 kHz using both equal pump average powers and equal pump energies to demonstrate that higher repetition rates allow spectra with higher signal-to-noise ratios to be obtained at lower pulse energies, a significant advance in the implementation of SE-FSRS...
November 1, 2016: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/27801594/effects-of-molecular-geometry-on-the-properties-of-compressed-diamondoid-crystals
#20
Fan Yang, Yu Lin, Maria Baldini, Jeremy E P Dahl, Robert M K Carlson, Wendy L Mao
Diamondoids are an intriguing group of carbon-based nanomaterials, which combine desired properties of inorganic nanomaterials and small hydrocarbon molecules with atomic-level uniformity. In this paper, we report the first comparative study on the effect of pressure on a series of diamondoid crystals with systematically varying molecular geometries and shapes, including zero-dimensional (0D) adamantane, one-dimensional (1D) diamantane, [121]tetramantane, [123]tetramantane, and [1212]pentamantane, two-dimensional (2D) [12312]hexamantane, and three-dimensional (3D) triamantane and [1(2,3)4]pentamantane...
November 1, 2016: Journal of Physical Chemistry Letters
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