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Oriol Lamiel-Garcia, Kyoung Chul Ko, Jin Yong Lee, Stefan T Bromley, Francesc Illas
All electron relativistic density functional theory (DFT) based calculations using numerical atom-centered orbitals have been carried out to explore the relative stability, atomic and electronic structure of a series of stoichiometric TiO2 anatase nanoparticles explicitly containing up to 1365 atoms as a function of size and morphology. The nanoparticles under scrutiny exhibit octahedral or truncated octahedral structures and span the 1- 6 nm size range. Initial structures were obtained from a Wulff construction, thus exhibiting the most stable (101) and (001) anatase surfaces...
February 23, 2017: Journal of Chemical Theory and Computation
Lia Bally, Patrick Kempf, Thomas Zueger, Christian Speck, Nicola Pasi, Carlos Ciller, Katrin Feller, Hannah Loher, Robin Rosset, Matthias Wilhelm, Chris Boesch, Tania Buehler, Ayse S Dokumaci, Luc Tappy, Christoph Stettler
This paper aims to compare the metabolic effects of glucose-fructose co-ingestion (GLUFRU) with glucose alone (GLU) in exercising individuals with type 1 diabetes mellitus. Fifteen male individuals with type 1 diabetes (HbA1c 7.0% ± 0.6% (53 ± 7 mmol/mol)) underwent a 90 min iso-energetic continuous cycling session at 50% VO2max while ingesting combined glucose-fructose (GLUFRU) or glucose alone (GLU) to maintain stable glycaemia without insulin adjustment. GLUFRU and GLU were labelled with (13)C-fructose and (13)C-glucose, respectively...
February 21, 2017: Nutrients
Bote G Bruinsma, James H Avruch, Gautham V Sridharan, Pepijn D Weeder, Marie Louise Jacobs, Kerry Crisalli, Beth Amundsen, Robert J Porte, James F Markmann, Korkut Uygun, Heidi Yeh
BACKGROUND: The ongoing shortage of donor livers for transplantation and the increased use of marginal livers necessitate the development of accurate pretransplant tests of viability. Considering the importance energy status during transplantation, we aimed to correlate peritransplant energy cofactors to posttransplant outcome and subsequently model this in an ex vivo setting. METHODS: Sequential biopsies were taken from 19 donor livers postpreservation, as well as 30 min after portal venous (PVR) and hepatic arterial reperfusion (HAR) and analyzed by LC-MS for energetic cofactors (ATP/ADP/AMP, NADH/NAD, NADPH/NADP, FAD, GSSG/GSH)...
February 23, 2017: Transplantation
Rakesh Rajegowda, Sridhar Kannam, Remco Hartkamp, Sarith P Sathian
Thermal-gradient induced transport of ionic liquid (IL) and water droplets through a carbon nanotube (CNT) is investigated in this study using molecular dynamics simulations. Energetic analysis indicates that IL transport through a CNT is driven primarily by the fluid-solid interaction, while fluid-fluid interactions dominate in water-CNT systems. Droplet diffusion analysis via the Moment Scaling Spectrum reveals sub-diffusive motion of the IL droplet, in contrast to the self-diffusive motion of the water droplet...
February 23, 2017: Nanotechnology
David E Chavez, Damon A Parrish, Lauren Mitchell, Greg H Imler
This study presents the synthesis and characterization of the oxidation products of 3,6-diazido-1,2,4,5-tetrazine (1) and 6-amino-[1,5-b]tetrazolo-1,2,4,5-tetrazine (2). 3,6-Diazido-1,2,4,5-tetrazine-1,4-dioxide was produced from oxidation with peroxytrifluoroacetic acid, and more effectively using hypofluorous acid, and 2 can be oxidized to two different products, 6-amino-[1,5-b]tetrazolo-1,2,4,5-tetrazine mono-N-oxide and di-N-oxide. These N-oxide compounds display promising performance properties as energetic materials...
February 23, 2017: Angewandte Chemie
Paulo R Bueno, David A Miranda
Molecular and supramolecular systems are essentially mesoscopic in character. The electron self-exchange, in the case of energy fluctuations, or electron transfer/transport, in the case of the presence of an externally driven electrochemical potential, between mesoscopic sites is energetically driven in such a manner where the electrochemical capacitance (C[small mu, Greek, macron]) is fundamental. Thus, the electron transfer/transport through channels connecting two distinct energetic (ΔE[small mu, Greek, macron]) and spatially separated mesoscopic sites is capacitively modulated...
February 22, 2017: Physical Chemistry Chemical Physics: PCCP
Sergey N Filimonov, Wei Liu, Alexandre Tkatchenko
The design of novel elementary surface processes is important for applications in catalysis, single-molecule junctions, molecular sensors, switches and surface mounted molecular machines. Here we demonstrate by van der Waals inclusive density functional theory calculations that a small and relatively simple heteroaromatic compound s-triazine (C$_3$H$_3$N$_3$) unexpectedly possesses five metastable states when adsorbed on the Pt(111) surface. This diversity of the adsorption states stems from an interplay between versatile molecule/surface chemical bonding and van der Waals interactions and from ``softening'' of the aromatic ring by nitrogen substitution, which makes folding of the aromatic ring energetically much less demanding as compared to benzene...
February 23, 2017: Journal of Physical Chemistry Letters
Martin Rotheut, Peter Quicker
The residence of municipal solid waste within a landfill body results in a significant change of material properties. Experiences with the energetic utilisation of the burnable fractions from formerly landfilled waste are hardly documented, the influence of refuse derived fuels (RDF) from such materials on the performance of modern waste-to-energy plants is not sufficiently described in scientific literature. Therefore this study focuses on the energetic utilisation of refuse derived fuel from landfilled waste, processed in a mechanical waste treatment facility, and the impact of the material on the operation of the incineration plant...
February 19, 2017: Waste Management
Azar Farjamnia, Bret Jackson
A quantum approach based on an expansion in vibrationally adiabatic eigenstates is used to explore the dissociative chemisorption of CO2 on Ni(100). The largest barrier to reaction corresponds to the formation of a bent anionic molecular precursor, bound to the surface by about 0.24 eV. The barrier to dissociation from this state is small. Our computed dissociative sticking probabilities on Ni(100) for molecules in the ground state are in very good agreement with available experimental data, reasonably reproducing the variation in reactivity with collision energy...
February 21, 2017: Journal of Chemical Physics
Ming L Cheuk, Callum M Johnston, June-Chiew Han, Denis S Loiselle, Poul M F Nielsen, Andrew J Taberner, Ming L Cheuk, Callum M Johnston, June-Chiew Han, Denis S Loiselle, Poul M F Nielsen, Andrew J Taberner, June-Chiew Han, Callum M Johnston, Poul M F Nielsen, Ming L Cheuk, Denis S Loiselle, Andrew J Taberner
Heat liberated from isolated cardiac muscle has been used to inform us of thermo-mechanical processes that occur during a contraction. However, for comparisons between different samples to be useful, the heat output needs to be normalized to volume. We have implemented an optical coherence tomograph (OCT), together with a flow-through calorimeter, to accurately determine both muscle volume and heat in the same measurement chamber. The heat rate for multiple stimulation frequencies were recorded and normalized to the volume captured by the OCT...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
Vivian M Lau, William C Pfalzgraff, Thomas E Markland, Matthew W Kanan
Competing pathways in catalytic reactions often involve transition states with very different charge distributions, but this difference is rarely exploited to control selectivity. The proximity of a counterion to a charged catalyst in an ion paired complex gives rise to strong electrostatic interactions that could be used to energetically differentiate transition states. Here we investigate the effects of ion pairing on the regioselectivity of the hydroarylation of 3-substituted phenyl propargyl ethers catalyzed by cationic Au(I) complexes, which forms a mixture of 5- and 7-substituted 2H-chromenes...
February 22, 2017: Journal of the American Chemical Society
Yevgen P Yurenko, Jan Novotný, Radek Marek
The topology and energetics of guanine (G) quadruplexes is governed by supramolecular interactions within their strands. In this work, we performed an extensive QM study of supramolecular interactions shaping the stems of (4+0) parallel (P) and (2+2) antiparallel (AP) systems. The large-scale (~ 400 atoms) models of P and AP were constructed from high-quality experimental structures. The results evidence that each of the P and AP structures is shaped by a distinct network of supramolecular interactions. The analysis of electron topological characteristics of H-bonds in P and AP systems indicates that the P model benefits from the stronger intra-tetrad H-bonding...
February 22, 2017: Chemistry: a European Journal
Jiasheng Lu, Ivan Hung, Andreas Brinkmann, Zhehong Gan, Xianqi Kong, Gang Wu
While NMR and IR spectroscopic signatures and structural characteristics of low-barrier hydrogen bond (LBHB) formation are well documented in the literature, direct measurement of the LBHB energy is difficult. Here, we show that solid-state (17) O NMR spectroscopy can provide unique information about the energy required to break a LBHB. Our solid-state (17) O NMR data show that the HB enthalpy of the O⋅⋅⋅H⋅⋅⋅N LBHB formed in crystalline nicotinic acid is only 7.7±0.5 kcal mol(-1) , suggesting that not all LBHBs are particularly strong...
February 22, 2017: Angewandte Chemie
K McCluskey, J Carlos Penedo
Riboswitches are short RNA motifs that sensitively and selectively bind cognate ligands to modulate gene expression. Like protein receptor-ligand pairs, their binding dynamics are traditionally categorized as following one of two paradigmatic mechanisms: conformational selection and induced fit. In conformational selection, ligand binding stabilizes a particular state already present in the receptor's dynamic ensemble. In induced fit, ligand-receptor interactions enable the system to overcome the energetic barrier into a previously inaccessible state...
February 22, 2017: Physical Chemistry Chemical Physics: PCCP
Susanne Jenni-Eiermann
Migrating birds are known to fly non-stop for thousands of kilometres without food or water intake and at a high metabolic rate thereby relying on energy stores which were built up preceding a flight bout. Hence, from a physiological point of view the metabolism of a migrant has to switch between an active fasting phase during flight and a fuelling phase during stopover. To meet the energetic and water requirements of endurance flight, migratory birds have to store an optimal fuel composition and they have to be able to quickly mobilize and deliver sufficient energy to the working flight muscles...
February 21, 2017: Journal of Comparative Physiology. A, Neuroethology, Sensory, Neural, and Behavioral Physiology
S Rählmann, H Meister
BACKGROUND: In communication situations with multiple speakers, speech recognition is adversely affected by energetic masking (EM) and informational masking (IM). IM characterizes masking effects caused by irrelevant information from competing speakers. This work investigates an approach to assess IM based on the Oldenburg Sentence Test (OLSA). Furthermore, the influence of interaural time differences (ITD) and aging effects on IM are considered. MATERIALS AND METHODS: IM was measured by superimposing two sentences from the OLSA...
February 21, 2017: HNO
E Lalik, G Mordarski, R P Socha, A Drelinkiewicz
A microcalorimetric method has been combined with a potentiostatic method to measure simultaneously the rate of heat evolution and the electrical current in a powdered sample of palladium during thermokinetic oscillations accompanying the sorption of deuterium in the metal. Deterministic chaos has been confirmed in the temporal variations in current (of ca. 1-4 mA) on the onset of both the sorption and the desorption of deuterium from Pd. It has been found that the first derivative of the current in time, dI/dt, turns out to be correlated precisely with the periodicity of thermokinetic oscillations...
February 22, 2017: Physical Chemistry Chemical Physics: PCCP
Gangtao Dai, Zhiqiang Zhong, Xiaofeng Wu, Shiping Zhan, Shigang Hu, Pan Hu, Junshan Hu, Shaobing Wu, Junbo Han, Yunxin Liu
Lanthanide doped upconversion nanoparticles NaGdF4:Yb3+/Er3+ received increasing attention due to their unique optical-magnetic bifunctional properties. Here, we show that the luminescent intensity from NaGdF4:Yb3+/Er3+ nanoparticles decreases monotonously with increasing the applied magnetic field from 0 to 37.1 T, while Plasmon enhanced upconversion luminescence in Au/NaGdF4:Yb3+/Er3+ nanocomposite is independent from a magnetic field lower than 6 T. The surface plasmon resonances could compensate for the energetic mismatching between the excitation light and the energy level gaps induced by magnetic field and enhance the radiative efficiency that are main factors for achieving this stable upconversion emission in this nanocomposite under a magnetic field not higher than 6 T...
February 22, 2017: Nanotechnology
John A Rohde, David D Thomas, Joseph M Muretta
Omecamtiv mecarbil (OM), a putative heart failure therapeutic, increases cardiac contractility. We hypothesize that it does this by changing the structural kinetics of the myosin powerstroke. We tested this directly by performing transient time-resolved FRET on a ventricular cardiac myosin biosensor. Our results demonstrate that OM stabilizes myosin's prepowerstroke structural state, supporting previous measurements showing that the drug shifts the equilibrium constant for myosin-catalyzed ATP hydrolysis toward the posthydrolysis biochemical state...
February 21, 2017: Proceedings of the National Academy of Sciences of the United States of America
Natalia Comino, Javier Cifuente, Alberto Marina, Ane Orrantia, Ander Eguskiza, Marcelo E Guerin
ADP-glucose pyrophosphorylase (AGPase) controls bacterial glycogen and plant starch biosynthetic pathways, the most common carbon storage polysaccharides in nature. AGPase activity is allosterically regulated by a series of metabolites in the energetic flux within the cell. Very recently, we reported the first crystal structures of the paradigmatic AGPase from Escherichia coli (EcAGPase) in complex with its preferred physiological negative and positive allosteric regulators, adenosine-5'-monophosphate (AMP) and fructose-1,6-bisphosphate (FBP), respectively...
February 21, 2017: Journal of Biological Chemistry
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