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Subtle energies

Jingwen Zhu, Emilie-Laure Zins, Mohammad Esmaïl Alikhani
For over a decade, amine-borane has been considered as a potential chemical hydrogen vector in the context of a search for cleaner energy sources. When catalyzed by organometallic complexes, the reaction mechanisms currently considered involve the formation of β-BH agostic intermediates. A thorough understanding of these intermediates may constitute a crucial step toward the identification of ideal catalysts. Topological approaches such as QTAIM and ELF revealed to be particularly suitable for the description of β-agostic interactions...
December 2016: Journal of Molecular Modeling
Juan Jesus Lopez Gonzalez, María Mar Quesada-Moreno, Juan Ramón Avilés-Moreno, Thérèse R Huet, M Eugenia Sanz, Donatella Loru, Natasha Jarman
Monoterpenoids are biogenic volatile organic compounds (BVOCs) that play a major role in atmospheric chemistry, participating in the formation of aerosols. In this work, the monoterpenoid R-(+)-limonene oxide (C₁₀H₁₆O) has been characterized in the gas phase by Fourier transform microwave spectroscopy in a supersonic jet. Five conformers of limonene oxide, four equatorial and one axial considering the configuration of the isopropenyl group, have been unambiguously identified from the analysis of the rotational spectrum...
November 23, 2016: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
John Tenayuca, Kimberley Cousins, Shumei Yang, Lubo Zhang
Cytosine methylation at CpG dinucleotides is a chief mechanism in epigenetic modification of gene expression patterns. Previous studies demonstrated that increased CpG methylation of Sp1 sites at -268 and -346 of protein kinase C  promoter repressed the gene expression. The present study investigated the impact of CpG methylation on the Sp1 binding via molecular modeling and electrophoretic mobility shift assay. Each of the Sp1 sites contain two CpGs. Methylation of either CpG lowered the binding affinity of Sp1, whereas methylation of both CpGs produced a greater decrease in the binding affinity...
November 16, 2016: Current Topics in Medicinal Chemistry
Ravi G Kurumbail, Matthew F Calabrese
AMP-activated protein kinase is a family of heterotrimeric serine/threonine protein kinases that come in twelve different flavors. They serve an essential function in all eukaryotes of conserving cellular energy levels. AMPK complexes are regulated by changes in cellular AMP:ATP or ADP:ATP ratios and by a number of neutraceuticals and some of the widely-used diabetes medications such as metformin and thiazolinonediones. Moreover, biochemical activities of AMPK are tightly regulated by phosphorylation or dephosphorylation by upstream kinases and phosphatases respectively...
2016: EXS
Jeremy D Podolnick, Daniel S Donovan, Nicholas DeBellis, Alejandro Pino
BACKGROUND: Lisfranc (tarsometatarsal joint) injuries are relatively rare, accounting for less than 1% of all fractures, and as many as 20% of subtle Lisfranc injuries are missed at the initial patient presentation. An undiagnosed Lisfranc injury can have devastating consequences to the patient. Therefore, any factor that can raise a clinician's index of suspicion to make this diagnosis is potentially important. The cavus foot has been associated with various maladies of the lower extremity, but to our knowledge, it has not been reported to be associated with Lisfranc injury...
October 28, 2016: Clinical Orthopaedics and related Research
Ricardo Vega Monroy, Guillermo Salazar Cohen
In this work we present a theory, which is able to explain the non-monotonic decreasing behavior (observed in experimental data(1-11)) of the graphene terahertz conductivity with the increase of the field frequency. In this connection, the displacement of the structure of topological states inside the energy band gap, which appears in graphene due to the strong photon-electron coupling, and the narrowing of this gap, as result of electron transitions from bound photon-dressed electron states to extended states outside the energy gap driven by the field frequency, lead to a periodic change of singularities near the edge of the band gap, resulting in subtle quantum oscillations of the dynamical terahertz conductivity...
October 25, 2016: Nano Letters
Mohammad Goli, Shant Shahbazian
Recently, it has been demonstrated that the domain-averaged exchange-correlation energies, V(xc) , are capable of tracing the covalent character of atom-atom interactions unequivocally and thus pave the way for detailed bonding analysis within the context of the quantum theory of atoms in molecules (QTAIM) [M. García-Revilla, E. Francisco, P. L. Popelier, A. Martín Pendás, ChemPhysChem 2013, 14, 1211-1218]. Herein, the concept of V(xc) is extended within the context of the newly developed multicomponent QTAIM (MC-QTAIM)...
October 25, 2016: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
Laura Chasmer, Chris Hopkinson
This study demonstrates linkages between the 1997/1998 El Niño/Southern Oscillation index and a threshold shift to increased permafrost loss within a southern Taiga Plains watershed, Northwest Territories, Canada. Three-dimensional contraction of permafrost plateaus and changes in vegetation structural characteristics are determined from multitemporal airborne Light Detection And Ranging (LiDAR) surveys in 2008, 2011 and 2015. Morphological changes in permafrost cover are compared with optical image analogues from 1970, 1977, 2000 and 2008 and time-series hydro-climate data...
October 22, 2016: Global Change Biology
Elisabeth Therese Ulrikkeholm, Martin Hangaard Hansen, Jan Rossmeisl, Ib Chorkendorff
Gd modified Pt(111) single crystals have been prepared in an ultra high vacuum (UHV). By vacuum deposition of ∼200 Å Gd on a sample heated to 800 °C, a Pt5Gd alloy terminated by a single atomic layer of Pt was formed. Subsequently the surfaces were characterized using low energy electron diffraction (LEED), showing that a highly ordered crystal structure had appeared. To study the molecular dynamics on this surface a detailed study of the CO adsorption on the surface was conducted using temperature programmed desorption (TPD) of CO...
October 19, 2016: Physical Chemistry Chemical Physics: PCCP
Grzegorz Szklarz, Karolina Adrjanowicz, Mateusz Dulski, Justyna Knapik, Marian Paluch
In this work, we have carefully investigated the molecular dynamics in the supercooled liquid and glassy states of the pharmaceutical agent fenofibrate. To do that dielectric relaxation studies at ambient and the elevated pressure were performed. Data collected at atmospheric pressure were found to be in a good agreement with that already reported in the literature. High-pressure studies enable us to distinguish the secondary relaxation processes of the different molecular origin. This includes (i) pressure insensitive $\gamma$-relaxation of the activation energy $E_a$=28 kJ/mol and (ii) $\beta$-relaxation that senses the density increase and originates most probably from the intermolecular movements ($E_a$=77 kJ/mol at 480 MPa)...
October 17, 2016: Journal of Physical Chemistry. B
Tony Rosen, Elizabeth M Bloemen, Jasmin Harpe, Allen M Sanchez, Kevin W Mennitt, Thomas J McCarthy, Refky Nicola, Kieran Murphy, Veronica M LoFaso, Neal Flomenbaum, Mark S Lachs
OBJECTIVE: Elder abuse is underrecognized, and identification of subtle cases requires a high index of suspicion among all health care providers. Because many geriatric injury victims undergo radiographic imaging, diagnostic radiologists may be well positioned to identify injury patterns suggestive of abuse. Little is known about radiologists' experience with elder abuse. Our goal was to describe knowledge, attitudes, training, and practice experience in elder abuse detection among diagnostic radiologists...
December 2016: AJR. American Journal of Roentgenology
Xiaoni Qu, Lianjie Zhai, Bozhou Wang, Qing Wei, Gang Xie, Sanping Chen, Shengli Gao
The persistent challenge in the field of energetic materials is how to synthesize energetic compounds with high density, high heat of detonation and outstanding detonation performance by gathering the maximum number of energetic groups in the smallest volume. The self-assembly of energetic groups with metal ions is crucially influenced by the solvent conditions. Here, the reaction of Cu(NO3)2·3H2O with 3-nitro-1H-1,2,4-triazole (Hntz) in aqueous ammonia under hydrothermal conditions via a self-assembly strategy yielded the Cu(i) energetic compound [Cu(ntz)]n (1)...
October 10, 2016: Dalton Transactions: An International Journal of Inorganic Chemistry
Anja Poblotzki, Jonas Altnöder, Martin A Suhm
Methanol is shown to engage two nearly equivalent solvation sites in 2,5-dimethylfuran, the electron-rich π cloud and the electron-deficient oxygen site. The latter only wins by a slight margin, thanks to the methyl group undergoing secondary interactions with the ring. These secondary attractions reduce the hydrogen bond-induced OH frequency shift of the OH-O contact, whereas the π cloud allows for a combined action of both binding mechanisms in the OH-π arrangement. In total, the hydrophobic character of 2,5-dimethylfuran is well reflected in the weak pair interactions, as judged by the small solvation shifts...
October 5, 2016: Physical Chemistry Chemical Physics: PCCP
Simon J Schreiner, Thomas Kirchner, Michael Wyss, Jiri M G Van Bergen, Frances C Quevenco, Stefanie C Steininger, Erica Y Griffith, Irene Meier, Lars Michels, Anton F Gietl, Sandra E Leh, Adam M Brickman, Christoph Hock, Roger M Nitsch, Klaas P Pruessmann, Anke Henning, Paul G Unschuld
Low episodic memory performance characterizes elderly subjects at increased risk for Alzheimer's disease (AD) and may reflect neuronal dysfunction within the posterior cingulate cortex and precuneus (PCP) region. To investigate a potential association between cerebral neurometabolism and low episodic memory in the absence of cognitive impairment, tissue-specific magnetic resonance spectroscopic imaging at ultrahigh field strength of 7 Tesla was used to investigate the PCP region in a healthy elderly study population (n = 30, age 70 ± 5...
August 31, 2016: Neurobiology of Aging
Karthika Suresh, Shivprasad Patil, Pattuparambil Ramanpillai Rajamohanan, Guruswamy Kumaraswamy
Subtle variations in the preparation of ice-templated nanoparticle assemblies yield monoliths that are chemically identical, but that exhibit qualitatively different mechanical behavior. We ice template aqueous dispersions to prepare macroporous monoliths comprising largely of silica nanoparticles held together by a crosslinked polymer mesh. When the polymer is crosslinked in the presence of ice crystals, we obtain an elastic sponge that is capable of recovery after imposition of large compressive strains (up to 80%)...
October 7, 2016: Langmuir: the ACS Journal of Surfaces and Colloids
James J P Stewart
A new method for predicting the energy contributions to substrate binding and to specificity has been developed. Conventional global optimization methods do not permit the subtle effects responsible for these properties to be modeled with sufficient precision to allow confidence to be placed in the results, but by making simple alterations to the model, the precisions of the various energies involved can be improved from about ±2 kcal mol(-1) to ±0.1 kcal mol(-1). This technique was applied to the oxidized nucleotide pyrophosphohydrolase enzyme MTH1...
November 2016: Journal of Molecular Modeling
Mireia Díaz-Lobo, Alda Lisa Concia, Livia Gómez, Pere Clapés, Ignacio Fita, Joan J Guinovart, Joan C Ferrer
Glycogen synthase (GS) and glycogen phosphorylase (GP) are the key enzymes that control, respectively, the synthesis and degradation of glycogen, a multi-branched glucose polymer that serves as a form of energy storage in bacteria, fungi and animals. An abnormal glycogen metabolism is associated with several human diseases. Thus, GS and GP constitute adequate pharmacological targets to modulate cellular glycogen levels by means of their selective inhibition. The compound 1,4-dideoxy-1,4-imino-d-arabinitol (DAB) is a known potent inhibitor of GP...
September 26, 2016: Organic & Biomolecular Chemistry
Anthony Cirri, Alexey Silakov, Lasse Jensen, Benjamin J Lear
Thiolate-protected gold nanoparticles have a rich history as model systems for understanding the physical and chemical properties of metallic nanoscale materials that, in turn, form the basis for applications in areas such as molecular electronics, photocatalytic systems, and plasmonic solar cells. It is well known that the electronic properties of gold nanoparticles can be tuned by modifying the geometry, size and dielectric surrounding of the particle. However, much less is known of how modifications to the surface chemistry modulates the electronic properties of gold nanoparticles...
September 14, 2016: Physical Chemistry Chemical Physics: PCCP
Keith Izod, Peter Evans, Paul G Waddell, Michael R Probert
A rare P-E π interaction between the lone pair of a planar P center and the vacant p orbital at the Ge or Sn center provides efficient stabilization for P-substituted tetrylenes (R2P)2E (E = Ge, Sn) and enables isolation of the first example of a compound with a crystallographically authenticated P═Sn bond. Subtle changes in the electronic properties of the bulky aryl substituents in these compounds change the preference for planar versus pyramidal P centers in the solid state; however, variable-temperature NMR spectroscopy indicates that in solution these species are subject to a dynamic equilibrium, which interconverts the planar and pyramidal P centers...
October 17, 2016: Inorganic Chemistry
Rory P Wilson, Mark D Holton, James S Walker, Emily L C Shepard, D Mike Scantlebury, Vianney L Wilson, Gwendoline I Wilson, Brenda Tysse, Mike Gravenor, Javier Ciancio, Melitta A McNarry, Kelly A Mackintosh, Lama Qasem, Frank Rosell, Patricia M Graf, Flavio Quintana, Agustina Gomez-Laich, Juan-Emilio Sala, Christina C Mulvenna, Nicola J Marks, Mark W Jones
BACKGROUND: We are increasingly using recording devices with multiple sensors operating at high frequencies to produce large volumes of data which are problematic to interpret. A particularly challenging example comes from studies on animals and humans where researchers use animal-attached accelerometers on moving subjects to attempt to quantify behaviour, energy expenditure and condition. RESULTS: The approach taken effectively concatinated three complex lines of acceleration into one visualization that highlighted patterns that were otherwise not obvious...
2016: Movement Ecology
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