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Dhananjai Saranadhi, Dayong Chen, Justin A Kleingartner, Siddarth Srinivasan, Robert E Cohen, Gareth H McKinley
Skin friction drag contributes a major portion of the total drag for small and large water vehicles at high Reynolds number (Re). One emerging approach to reducing drag is to use superhydrophobic surfaces to promote slip boundary conditions. However, the air layer or "plastron" trapped on submerged superhydrophobic surfaces often diminishes quickly under hydrostatic pressure and/or turbulent pressure fluctuations. We use active heating on a superhydrophobic surface to establish a stable vapor layer or "Leidenfrost" state at a relatively low superheat temperature...
October 2016: Science Advances
Jingbo Wei, Kun Liu, Gianmarco Radice
This paper presents a novel and simple method to analyze the absolute stability and the rotor speed stable region of a magnetically suspended rotor (MSR). At the beginning of the paper, a complex variable is introduced to describe the movement of the MSR and a complex coefficient transfer function is obtained accordingly. The equivalent stability relationship between this new variable and the two traditional deflection angles is also demonstrated in a simple way. The detailed characteristics of the open-loop MSR system with time delay are studied carefully based on the characteristics of its Nyquist curve...
October 13, 2016: ISA Transactions
G André Ng
Antiarrhythmic drug therapy has seen significant challenges over the past 3 decades with unexpected results from clinical trials such as CAST, SWORD and more recently PALLAS showing harm in patients whom antiarrhythmic drugs were given based on their intended antiarrhythmic actions and previously demonstrated efficacy. These results question whether the precise mechanism of action of the drugs was understood and highlight the complexity of the situation where there is the combination of multiple actions of the antiarrhythmic drugs on various molecular systems, some of which may be unknown with associated adverse outcome, and their interaction with pre-existing abnormality in disease states in patients treated...
October 12, 2016: Pharmacology & Therapeutics
M Bitter, V Milner
The periodically kicked rotor is a paradigm system for studying quantum effects on classically chaotic dynamics. The wave function of the quantum rotor localizes in angular momentum space, similarly to Anderson localization of the electronic wave function in disordered solids. Here, we observe dynamical localization in a system of true quantum rotors by subjecting nitrogen molecules to periodic sequences of femtosecond pulses. Exponential distribution of the molecular angular momentum-the hallmark of dynamical localization-is measured directly by means of coherent Raman scattering...
September 30, 2016: Physical Review Letters
Stephen O Evans, Michael B Jameson, Ray T M Cursons, Linda M Peters, Steve Bird, Gregory M Jacobson
DNA damage quantitation assays such as the comet assay have focused on the measurement of total nuclear damage per cell. The adoption of PCR-based techniques to quantify DNA damage has enabled sequence- and organelle-specific assessment of DNA lesions. Here we report on an adaptation of a qPCR technique to assess DNA damage in nuclear and mitochondrial targets relative to control. Novel aspects of this assay include application of the assay to the Rotor-Gene platform with optimized DNA polymerase/fluorophore/primer set combination in a touchdown PCR protocol...
October 8, 2016: Biology
Tomohiko G Sano, Kiyoshi Kanazawa, Hisao Hayakawa
This study numerically and analytically investigates the dynamics of a rotor under viscous or dry friction as a nonequilibrium probe of a granular gas. In order to demonstrate the role of the rotor as a probe for a nonequilibrium bath, the molecular dynamics (MD) simulation of the rotor is performed under viscous or dry friction surrounded by a steady granular gas under gravity. A one-to-one map between the velocity distribution function (VDF) of the granular gas and the angular distribution function for the rotor is theoretically derived...
September 2016: Physical Review. E
Lauren Peruffo, Janice D Boyd, Sharman Hoppes, Donald J Brightsmith
Blood biochemical values are useful as indicators of disease in veterinary practice and for health assessments of free-ranging animal populations. We analyzed blood biochemical values for free-living nestling and adult scarlet macaws ( Ara macao macao) in southeastern Peru with an Abaxis VetScan VS2 portable analyzer with Avian/Reptilian Profile Plus rotors. The resulting data were used to create provisional age-independent reference intervals for this instrument for wild scarlet macaw nestlings, calculate blood biochemical ranges for this instrument for wild adults, and examine age-related trends in nestlings...
September 2016: Journal of Avian Medicine and Surgery
Tomislav Suhina, Saeed Amirjalayer, Benedetta Mennucci, Sander Woutersen, Michiel Hilbers, Daniel Bonn, Albert Manfred Brouwer
The fluorescence intensity of molecular rotors containing the dicyanomethylenedihydrofuran (DCDHF) motif increases strongly with solvent viscosity. Single-bond and double-bond rotations have been proposed as pathways of non radiative decay for this and related molecular rotors. We show here that both are involved in the case of DCDHF rotors: fluorescence is quenched by rotation around the dicyanomethylene double bond in non polar solvents, but in a sufficiently polar environment rotation about a formally single bond leads to a dark internal charge transfer state...
October 13, 2016: Journal of Physical Chemistry Letters
Abraham Colin-Molina, Salvador Pérez-Estrada, Arian E Roa, Alvin Villagrana-Garcia, Simón Hernández-Ortega, Mario Rodríguez, Stuart E Brown, Braulio Rodríguez-Molina
Liquid-like dynamics of a covalent 1,4-phenylene rotator have been unveiled in 1 with a brominated stator showing type-II halogen bonds. This singular rotation is favored by synergistic molecular changes in stacked molecules, according to VT solid state NMR, (1)H T1 relaxometry and VT X-ray experiments of this highly crystalline compound.
October 3, 2016: Chemical Communications: Chem Comm
Georgette M Lang, Dirk Skaper, Frank Hampel, John A Gladysz
Three routes are explored to the title halide/cyanide complexes trans-Fe(CO)(NO)(X)(P((CH2)14)3P) (9c-X; X = Cl/Br/I/CN), the Fe(CO)(NO)(X) moieties of which can rotate within the diphosphine cages (ΔH(‡)/ΔS(‡) (kcal mol(-1)/eu(-1)) 5.9/-20.4 and 7.4/-23.9 for 9c-Cl and 9c-I from variable temperature (13)C NMR spectra). First, reactions of the known cationic complex trans-[Fe(CO)2(NO)(P((CH2)14)3P)](+) BF4(-) and Bu4N(+) X(-) give 9c-Cl/-Br/-I/-CN (75-83%). Second, reactions of the acyclic complexes trans-Fe(CO)(NO)(X)(P((CH2)mCH[double bond, length as m-dash]CH2)3)2 and Grubbs' catalyst afford the tris(cycloalkenes) trans-Fe(CO)(NO)(X)(P((CH2)mCH[double bond, length as m-dash]CH(CH2)m)3P) (m/X = 6/Cl,Br,I,CN, 7/Cl,Br, 8/Cl,Br) as mixtures of Z/E isomers (24-41%)...
October 18, 2016: Dalton Transactions: An International Journal of Inorganic Chemistry
Gaurav Jerath, Prakash Kishore Hazam, Shashi Shekhar, Vibin Ramakrishnan
Polypeptide chain has an invariant main-chain and a variant side-chain sequence. How the side-chain sequence determines fold in terms of its chemical constitution has been scrutinized extensively and verified periodically. However, a focussed investigation on the directive effect of side-chain geometry may provide important insights supplementing existing algorithms in mapping the geometrical evolution of protein chains and its structural preferences. Geometrically, folding of protein structure may be envisaged as the evolution of its geometric variables: ϕ, and ψ dihedral angles of polypeptide main-chain directed by χ1, and χ2 of side chain...
2016: PloS One
Wenchang Zhou, Vanessa Leone, José D Faraldo-Gómez
Recent years have witnessed a renewed interest in the ATP synthase as a drug target against human pathogens. Indeed, clinical, biochemical and structural data indicate that hydrophobic inhibitors targeting the membrane-embedded proton-binding sites of the c-subunit ring could serve as last-resort antibiotics against multi-drug resistant strains. However, because inhibition of the mitochondrial ATP synthase in humans is lethal, it is essential that these inhibitors be not only potent but also highly selective for the bacterial enzyme...
October 7, 2016: Journal of Physical Chemistry. B
Matthew J Murray, Hannah M Ogden, Carlos Toro, Qingnan Liu, Amy S Mullin
We report state-resolved collision dynamics for CO molecules prepared in an optical centrifuge and measured with high resolution transient IR absorption spectroscopy.Time-resolved polarization-sensitive measurements of excited CO molecules in the J=29 rotational state reveal that oriented angular momentum of CO rotors is relaxed by impulsive collisions.Translational energy gains for molecules in the initial plane of rotation are 3-fold larger than for randomized angular momentum orientations, indicating the presence of anisotropic kinetic energy...
October 6, 2016: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
Luyi Zong, Yujun Xie, Can Wang, Jian-Rong Li, Qianqian Li, Zhen Li
Unlike normal ACQ-to-AIE conversion by the introduction of aromatic rotors accompanying the realization of a twisted conformation and a prolonged π-system, in this communication, the adjustment of the flexible chains can reach this point with the tunable packing modes while the original π-system core and related properties of the aromatic naphthalene diimide remain nearly unchanged, providing an alternative approach for the inhibition of unwanted π-π stacking.
September 20, 2016: Chemical Communications: Chem Comm
Aruna K Mora, Prabhat K Singh, Birija S Patro, Sukhendu Nath
PicoGreen, a cyanine based ultrafast molecular rotor, shows high affinity towards amyloid fibrils and scores a much better sensitivity than Thioflavin-T, a gold standard probe for amyloid fibrils. Detailed spectroscopic and molecular docking studies have been performed to understand the mode of interaction between PicoGreen and amyloid fibrils.
October 6, 2016: Chemical Communications: Chem Comm
Jacek T Mika, Alexander J Thompson, Michael R Dent, Nicholas J Brooks, Jan Michiels, Johan Hofkens, Marina K Kuimova
The viscosity is a highly important parameter within the cell membrane, affecting the diffusion of small molecules and, hence, controlling the rates of intracellular reactions. There is significant interest in the direct, quantitative assessment of membrane viscosity. Here we report the use of fluorescence lifetime imaging microscopy of the molecular rotor BODIPY C10 in the membranes of live Escherichia coli bacteria to permit direct quantification of the viscosity. Using this approach, we investigated the viscosity in live E...
October 4, 2016: Biophysical Journal
Klaus Suhling
No abstract text is available yet for this article.
October 4, 2016: Biophysical Journal
Massimo Mella, E Curotto
We study the adsorption energetics and quantum properties of the molecular hydrogen isotopes H2, D2, and T2 onto the surface of rigid ammonia nanoclusters with quantum simulations and accurate model potential energy surfaces (PES). A highly efficient diffusion Monte Carlo (DMC) algorithm for rigid rotors allowed us to accurately define zero-point adsorption energies for the three isotopes, as well as the degree of translational and rotational delocalization that each affords on the surface. From the data emerges that the quantum adsorption energy (Eads) of T2 can be up to twice the one of H2 at 0 K, suggesting the possibility of exploiting some form of solid ammonia to selectivity separate hydrogen isotopes at low temperatures (≃20 K)...
October 5, 2016: Journal of Physical Chemistry. A
Ivan N Meshkov, Véronique Bulach, Yulia G Gorbunova, Nathalie Kyritsakas, Mikhail S Grigoriev, Aslan Yu Tsivadze, Mir Wais Hosseini
A new cationic molecular turnstile based on a P(V) porphyrin backbone bearing two pyridyl interaction sites, one at the meso position of the porphyrin and the other on the handle connected to the porphyrin through P-O bonds, was designed and synthesized. The dynamic behavior of the turnstile 2, investigated by 1D and 2D (1)H NMR techniques, showed that in the absence of an effector, the turnstile is in its open state and undergoes a free rotation of the rotor (the handle) around the stator (the porphyrin backbone)...
October 5, 2016: Inorganic Chemistry
Jian Lu, Yaqing Zhang, Harold Y Hwang, Benjamin K Ofori-Okai, Sharly Fleischer, Keith A Nelson
Ultrafast 2D spectroscopy uses correlated multiple light-matter interactions for retrieving dynamic features that may otherwise be hidden under the linear spectrum; its extension to the terahertz regime of the electromagnetic spectrum, where a rich variety of material degrees of freedom reside, remains an experimental challenge. We report a demonstration of ultrafast 2D terahertz spectroscopy of gas-phase molecular rotors at room temperature. Using time-delayed terahertz pulse pairs, we observe photon echoes and other nonlinear signals resulting from molecular dipole orientation induced by multiple terahertz field-dipole interactions...
October 4, 2016: Proceedings of the National Academy of Sciences of the United States of America
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