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Anirban Basu, Gopinatha Suresh Kumar
Interaction of proflavine with hemoglobin (Hgb) was studied employing spectroscopy, calorimetry, and atomic force microscopy. The equilibrium constant was found to be of the order 10(4)M(-1). The quenching of Hgb fluorescence by proflavine was due to the complex formation. Calculation of the molecular distance (r) between the donor (β-Trp37 of Hgb) and acceptor (proflavine) suggested that energy can be efficiently transferred from the β-Trp37 residue at the α1β2 interface of the protein to the dye. Proflavine induced significant secondary structural changes in Hgb...
October 12, 2016: Journal of Photochemistry and Photobiology. B, Biology
Nicolas Renaud, Michelle A Harris, Arunoday P N Singh, Yuri A Berlin, Mark A Ratner, Michael R Wasielewski, Frederick D Lewis, Ferdinand C Grozema
Charge transport through the DNA double helix is of fundamental interest in chemistry and biochemistry, but also has potential technological applications such as for DNA-based nanoelectronics. For the latter, it is of considerable interest to explore ways to influence or enhance charge transfer. In this Article we demonstrate a new mechanism for DNA charge transport, namely 'deep-hole transfer', which involves long-range migration of a hole through low-lying electronic states of the nucleobases. Here, we demonstrate, in a combined experimental and theoretical study, that it is possible to achieve such transfer behaviour by changing the energetics of charge injection...
November 2016: Nature Chemistry
Michael P Grubb, Philip M Coulter, Hugo J B Marroux, Balazs Hornung, Ryan S McMullen, Andrew J Orr-Ewing, Michael N R Ashfold
Spectroscopically observing the translational and rotational motion of solute molecules in liquid solutions is typically impeded by their interactions with the solvent, which conceal spectral detail through linewidth broadening. Here we show that unique insights into solute dynamics can be made with perfluorinated solvents, which interact weakly with solutes and provide a simplified liquid environment that helps to bridge the gap in our understanding of gas- and liquid-phase dynamics. Specifically, we show that in such solvents, the translational and rotational cooling of an energetic CN radical can be observed directly using ultrafast transient absorption spectroscopy...
November 2016: Nature Chemistry
Koichiro Saito, Ichiro Tanabe, Tetsu Tatsuma
Plasmon-induced charge separation (PICS) at the interface between a plasmonic nanoparticle and semiconductor is now widely used for photovoltaics and photocatalysis. Here we take advantage of PICS for site-selective nanoetching of silver nanocubes on TiO2 beyond the diffraction limit. A silver nanocube exhibits two resonance modes localized at the top and bottom of the nanocube (distal and proximal modes, respectively) when it is placed on TiO2. We achieved selective etching at the top and the bottom of the nanocubes by PICS based on the distal and proximal modes, respectively...
October 21, 2016: Journal of Physical Chemistry Letters
Ivan Ljubic, Aleksandar Sabljic, Marija Bonifacic
The reactions of α-hydroxyalkyl radicals in aqueous medium are of interest because they exhibit a rich variety of fundamentally important competing mechanisms, such as proton-coupled electron transfer (PCET), hydrogen atom transfer, free radical substitutions, abstractions and additions etc. We present a theoretical study of the mechanism and kinetics of the aqueous reactions of α-hydroxyisopropyl (2-propanol) radical with four halogenated organic substrates: iodoacetate (IAc), iodoacetamide (IAm), 5-bromouracil (5-BrU), and carbon tetrachloride (CCl4)...
October 21, 2016: Journal of Physical Chemistry. B
Miles A White, Gordon J Miller, Javier Vela
The first example of polytypism in the I-II-V semiconductors has been demonstrated with the synthesis of cubic LiZnSb by low temperature solution phase methods. This phase exhibits a unique coloring pattern that is novel for this class of compounds. The choice of site configuration has considerable impact on the band structure of these materials which, in turn, effects the transport properties. While the hexagonal polytype has been suggested as a promising n-type and extremely poor p-type thermoelectric material, the cubic analogue is calculated to have high efficiencies at 600K for both n- and p-type derivatives of 1...
October 21, 2016: Journal of the American Chemical Society
Mingzhu Xia, Yuting Chu, Tianyi Wang, Wu Lei, Fengyun Wang
As a kind of promising energetic materials, the double furazan-based and furoxan-based compounds have raised concerns of many researchers in recent years. In this paper, the optimized structures, energetic properties, heat of formation (HOF), detonation properties, and bond dissociation energies of these compounds were calculated by density functional theory (DFT) method. The results show that the N-O bond, which is close to the adjacent coordinated oxygen atom in furoxan ring, is more fragile than the other N-O bonds in the ring...
November 2016: Journal of Molecular Modeling
Yue Liao, Chih-Ping Chou, Jimi Huh, Adam Leventhal, Genevieve Dunton
Current knowledge about the relationship of physical activity with acute affective and physical feeling states is informed largely by lab-based studies, which have limited generalizability to the natural ecology. This study used ecological momentary assessment to assess subjective affective and physical feeling states in free-living settings across 4 days from 110 non-physically active adults (Age M = 40.4, SD = 9.7). Light physical activity (LPA) and moderate-to-vigorous physical activity (MVPA) were measured objectively by an accelerometer...
October 20, 2016: Journal of Behavioral Medicine
Yong-An Feng, Hao Qiu, Sa-Sha Yang, Jiang Du, Tong-Lai Zhang
In order to obtain high-performance energetic materials, in this work, carbonyl groups (C[double bond, length as m-dash]O) have been newly introduced as sole bridging groups in the field of energetic materials. To this end, two tailored green methods for the synthesis of carbonyl-bridged energetic compounds have been developed for the first time. One is a biomimetic synthesis, in which the conversion route of heme to biliverdin has been used to obtain metal-containing energetic compounds. The other one is an organocatalysis, in which guanidinium serves as an energetic catalyst to afford other energetic compounds...
October 21, 2016: Dalton Transactions: An International Journal of Inorganic Chemistry
Sohag Biswas, Bhabani S Mallik
We present the characteristic proton transfer process from water to the pyrazole anion, infrared signatures of hydroxyl groups and the free energy profile of the process in aqueous solution combining first principles simulations, wavelet analysis and metadynamics. Our results show that the presence of minimum three water molecules in the gas phase cluster with a particular arrangement is sufficient to facilitate the proton transfer process from water to the anion. The overall reaction is very rapid in aqueous solution, and the free energy barrier for this process is found to be 4...
October 21, 2016: Physical Chemistry Chemical Physics: PCCP
Daniela Albanesi, Diego de Mendoza
Phospholipids and fatty acids are not only one of the major components of cell membranes but also important metabolic intermediates in bacteria. Since the fatty acid biosynthetic pathway is essential and energetically expensive, organisms have developed a diversity of homeostatic mechanisms to fine-tune the concentration of lipids at particular levels. FapR is the first global regulator of lipid synthesis discovered in bacteria and is largely conserved in Gram-positive organisms including important human pathogens, such as Staphylococcus aureus, Bacillus anthracis, and Listeria monocytogenes...
2016: Frontiers in Molecular Biosciences
Casey T Clark, Alyson H Fleming, John Calambokidis, Nicholas M Kellar, Camryn D Allen, Krista N Catelani, Michelle Robbins, Nicole E Beaulieu, Debbie Steel, James T Harvey
Understanding reproductive rates of wild animal populations is crucially important for management and conservation. Assessing pregnancy status of free-ranging cetaceans has historically been difficult; however, recent advances in analytical techniques have allowed the diagnosis of pregnancy from small samples of blubber tissue. The primary objectives of this study were as follows: (i) to test the efficacy of blubber progesterone assays as a tool for diagnosing pregnancy in humpback whales (Megaptera novaeangliae); (ii) to estimate the pregnancy rate of humpback whales in Monterey Bay, California; and (iii) to investigate the relationship between stable isotopes and reproductive status of these whales...
2016: Conservation Physiology
Patrycja Podlaszczuk, Maciej Kamiński, Radosław Włodarczyk, Krzysztof Kaczmarek, Tomasz Janiszewski, Piotr Minias
BACKGROUND: Moult is one of the most costly activities in the annual cycle of birds and most avian species separate moult from other energy-demanding activities, such as migration. To this end, young birds tend to undergo the first post-juvenile moult before the onset of migration, but in some species the time window for the pre-migratory feather replacement is too narrow. We hypothesized that in such species an increased investment in the structural quality of juvenile feathers may allow to retain juvenile plumage throughout the entire migratory period and delay moult until arriving at wintering grounds, thus avoiding a moult-migration overlap...
2016: Frontiers in Zoology
Justin M Gorham, William A Osborn, Jeremiah W Woodcock, Keana C K Scott, John M Heddleston, Angela R Hight Walker, Jeffrey W Gilman
To better assess risks associated with nano-enabled products including multiwalled carbon nanotubes (MWCNT) within polymer matrices, it is important to understand how MWCNT are dispersed throughout the composite. The current study presents a method which employs imaging X-ray photoelectron spectroscopy (XPS) to chemically detect spatially segregated MWCNT rich regions at an epoxy composites surface by exploiting differential charging. MWCNT do not charge due to high conductivity and have previously been shown to energetically separate from their insulating surroundings when characterized by XPS...
January 2016: Carbon
Noah T Ashley, Greg E Demas
Multidirectional interactions among the immune, endocrine, and nervous systems have been demonstrated in humans and non-human animal models for many decades by the biomedical community, but ecological and evolutionary perspectives are lacking. Neuroendocrine-immune interactions can be conceptualized using a series of feedback loops, which culminate into distinct neuroendocrine-immune phenotypes. Behavior can exert profound influences on these phenotypes, which can in turn reciprocally modulate behavior. For example, the behavioral aspects of reproduction, including courtship, aggression, mate selection and parental behaviors can impinge upon neuroendocrine-immune interactions...
October 17, 2016: Hormones and Behavior
Christine L Madliger, Oliver P Love
The application of physiological measures to conservation monitoring has been gaining momentum and, while a suite of physiological traits are available to ascertain disturbance and condition in wildlife populations, glucocorticoids (i.e., GCs; cortisol and corticosterone) are the most heavily employed. The interpretation of GC levels as sensitive indicators of population change necessitates that GCs and metrics of population persistence are linked. However, the relationship between GCs and fitness may be highly context-dependent, changing direction, or significance, depending on the GC measure, fitness metric, life history stage, or other intrinsic and extrinsic contexts considered...
July 27, 2016: Ecological Applications: a Publication of the Ecological Society of America
David Samuel Johnson, R Scott Warren, Linda A Deegan, Thomas J Mozdzer
In saltmarsh plant communities, bottom-up pressure from nutrient enrichment is predicted to increase productivity, alter community structure, decrease biodiversity, and alter ecosystem functioning. Previous work supporting these predictions has been based largely on short-term, plot-level (e.g., 1-300 m(2) ) studies, which may miss landscape-level phenomena that drive ecosystem-level responses. We implemented an ecosystem-scale, nine-year nutrient experiment to examine how saltmarsh plants respond to simulated conditions of coastal eutrophication...
July 27, 2016: Ecological Applications: a Publication of the Ecological Society of America
Xiaoyang Shi, Hang Xiao, Klaus Lackner, Xi Chen
A great deal of information exists concerning the hydration of ions in bulk water. Much less noticeable, but equally ubiquitous is the hydration of ions holding on to several water molecules in nanoscopic pores or in natural air at low relative humidity. Such hydration of ions with a high ratio of ions to water molecules (up to 1:1) are essential in determining the energetics of many physical and chemical systems. Here we present a quantitative analysis of the energetics of ion hydration in nanopores based on molecular modeling of a series of basic salts associated with different numbers of water molecules...
October 20, 2016: Chemistry: a European Journal
Assaf Manor, Nimrod Kruger, Tamilarasan Sabapathy, Carmel Rotschild
The maximal Shockley-Queisser efficiency limit of 41% for single-junction photovoltaics is primarily caused by heat dissipation following energetic-photon absorption. Solar-thermophotovoltaics concepts attempt to harvest this heat loss, but the required high temperatures (T>2,000 K) hinder device realization. Conversely, we have recently demonstrated how thermally enhanced photoluminescence is an efficient optical heat-pump that operates in comparably low temperatures. Here we theoretically and experimentally demonstrate such a thermally enhanced photoluminescence based solar-energy converter...
October 20, 2016: Nature Communications
Raquel Fonseca, Rui A Carvalho, Cristina Lemos, Ana C Sequeira, Inês R Pita, Fábio Carvalho, Carlos D Silva, Rui D S Prediger, Ivana Jarak, Rodrigo A Cunha, Carlos A Fontes Ribeiro, Attila Köfalvi, Frederico C Pereira
INTRODUCTION: We recently showed that a single high dose of methamphetamine (METH) induces a persistent frontal cortical monoamine depletion that is accompanied by helpless-like behavior in mice. However, brain metabolic alterations underlying both neurochemical and mood alterations remain unknown. AIMS: Herein, we aimed at characterizing frontal cortical metabolic alterations associated with early negative mood behavior triggered by METH. Adult C57BL/6 mice were injected with METH (30 mg/kg, i...
October 19, 2016: CNS Neuroscience & Therapeutics
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