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Kevin S Stanley, Dylan J Meyer, Craig Gatto, Pablo Artigas
The Na(+),K(+)-ATPase (NKA or Na/K pump) hydrolyzes one ATP to exchange three intracellular Na+ (Na(+)i) for two extracellular K+ (K(+)o) across the plasma membrane by cycling through a set of reversible transitions between phosphorylated and dephosphorylated conformations, alternately opening ion-binding sites externally (E2) or internally (E1). With subsaturating [Na(+)]o and [K(+)]o, the phosphorylated E2P conformation passively imports protons generating an inward current (IH), which may be exacerbated in NKA-subunit mutations associated with human disease...
December 6, 2016: Biophysical Journal
Christina Grønberg, Oleg Sitsel, Erik Lindahl, Pontus Gourdon, Magnus Andersson
Cu(+)-specific P-type ATPase membrane protein transporters regulate cellular copper levels. The lack of crystal structures in Cu(+)-binding states has limited our understanding of how ion entry and binding are achieved. Here, we characterize the molecular basis of Cu(+) entry using molecular-dynamics simulations, structural modeling, and in vitro and in vivo functional assays. Protein structural rearrangements resulting in the exposure of positive charges to bulk solvent rather than to lipid phosphates indicate a direct molecular role of the putative docking platform in Cu(+) delivery...
December 6, 2016: Biophysical Journal
Eliedonna Cacao, Francis A Cucinotta
Radiation-induced impairment of neurogenesis in the hippocampal dentate gyrus is a concern due to its reported association with cognitive detriments after radiotherapy for brain cancers and the possible risks to astronauts chronically exposed to space radiation. Here, we have extended our recent work in a mouse model of impaired neurogenesis after exposure to low-linear energy transfer (LET) heavy ion radiation. To our knowledge, this is the first report of a predictive mathematical model of radiation-induced changes to neurogenesis for a variety of radiation types after acute or fractionated irradiation...
December 7, 2016: Radiation Research
J Lasne, A Noblet, C Szopa, R Navarro-González, M Cabane, O Poch, F Stalport, P François, S K Atreya, P Coll
In 1976, the Viking landers carried out the most comprehensive search for organics and microbial life in the martian regolith. Their results indicate that Mars' surface is lifeless and, surprisingly, depleted in organics at part-per-billion levels. Several biology experiments on the Viking landers gave controversial results that have since been explained by the presence of oxidizing agents on the surface of Mars. These oxidants may degrade abiotic or biological organics, resulting in their nondetection in the regolith...
December 7, 2016: Astrobiology
J M Little, E Y Choueiri
Electron cooling in a magnetically expanding plasma, which is a fundamental process for plasma flow and detachment in magnetic nozzles, is experimentally investigated using a radio frequency plasma source and magnetic nozzle (MN). Probe measurements of the plasma density, potential, and electron temperature along the center line of the MN indicate that the expansion follows a polytropic law with exponent γ_{e}=1.15±0.03. This value contradicts isothermal electron expansion, γ_{e}=1, which is commonly assumed in MN models...
November 25, 2016: Physical Review Letters
Swagato Mukherjee, Raju Venugopalan, Yi Yin
Exploiting the universality between the QCD critical point and the three-dimensional Ising model, closed form expressions derived for nonequilibrium critical cumulants on the crossover side of the critical point reveal that they can differ in both magnitude and sign from equilibrium expectations. We demonstrate here that key elements of the Kibble-Zurek framework of nonequilibrium phase transitions can be employed to describe the dynamics of these critical cumulants. Our results suggest that observables sensitive to critical dynamics in heavy-ion collisions should be expressible as universal scaling functions, thereby providing powerful model-independent guidance in searches for the QCD critical point...
November 25, 2016: Physical Review Letters
S Weidt, J Randall, S C Webster, K Lake, A E Webb, I Cohen, T Navickas, B Lekitsch, A Retzker, W K Hensinger
Trapped ions are a promising tool for building a large-scale quantum computer. However, the number of required radiation fields for the realization of quantum gates in any proposed ion-based architecture scales with the number of ions within the quantum computer, posing a major obstacle when imagining a device with millions of ions. Here, we present a fundamentally different approach for trapped-ion quantum computing where this detrimental scaling vanishes. The method is based on individually controlled voltages applied to each logic gate location to facilitate the actual gate operation analogous to a traditional transistor architecture within a classical computer processor...
November 25, 2016: Physical Review Letters
Anna Gątarska, Joanna Ciborska, Elżbieta Tońska
Background: Natural mineral waters are purchased and consumed according to consumer preferences and possible recommendations. The choice of appropriate water should take into account not only the general level of mineralization but also the content of individual components, including electrolytes such as sodium and potassium. Sodium is necessary to ensure the proper physiological functions of the body. It is defined as a health risk factor only when its excessive intake occurs. Potassium acts antagonistically towards sodium and calcium ions, contributes to a reduction of the volume of extracellular fluids and at the same time reduces muscle tension and permeability of cell membranes...
2016: Roczniki Państwowego Zakładu Higieny
Pengfei Xu, Yingming Yao, Xin Xu
Three rare-earth aryloxide ion pairs ([L1REOAr]+[B(C6F5)4]-; L1 = CH3C(2,6-iPr2C6H3N)CHC(CH3)(NCH2CH2PPh2); RE = Sc, Y, Lu; Ar = 2,6-tBu2C6H3) are reported, which feature RE/P combinations exhibiting frustrated Lewis pair (FLP)-like 1,4-addition reactions towards conjugated carbonyl substrates e.g. enone, ynone and acrylic substrates. Furthermore, these RE/P complexes are found to be effective catalysts for polymerizations of conjugated polar alkene monomers. Mechanistic studies reveal that the polymerizations are initiated by novel FLP-type 1,4-additions, rather than traditional and ubiquitous covalent RE-E (E = H, C, N, etc...
December 7, 2016: Chemistry: a European Journal
Robin Ion, Aled Jones, Richard Craven
This article considers the issue of poor care and how nurses should respond when they encounter it. Several reports and inquiries into failings in care have called into question the standards of care provided by nurses. Of equal concern is the observation that in some instances, poor care is unreported. While there may be underlying structural and organisational reasons for this, it is contended that nurses have a legal, moral and professional obligation to report poor care when they become aware of it.
December 7, 2016: Nursing Standard
Toshiro Yamanaka, Hiroe Nakagawa, Shigetaka Tsubouchi, Yasuhiro Domi, Takayuki Doi, Takeshi Abe, Zempachi Ogumi
Lithium ion batteries have attracted considerable attention due to their high power density. The change in concentration of salt in the electrolyte solution in lithium ion batteries during operation causes serious degradation of battery performance. In this work, a new method of in situ Raman spectroscopy using ultrafine multi-fiber probes was developed to simultaneously study the concentrations of ions at several different positions in the electrolyte solution in deep narrow spaces between the electrodes in batteries...
December 7, 2016: ChemSusChem
Kai-Hsin Liou, Dun-Yen Kang, Li-Chiang Lin
Water shortage has become a critical issue. To facilitate the large-scale deployment of reverse-osmosis water desalination to produce fresh water, discovering novel membranes is essential. Here, we computationally demonstrate the great potential of single-walled aluminosilicate nanotubes (AlSiNTs), materials that can be synthesized through scalable methods, in desalination. State-of-the-art molecular dynamics simulations were employed to investigate the desalination performance and structure-performance relationship of AlSiNTs...
November 4, 2016: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
Angel Terron, Blas Moreno-Vachiano, Antonio Bauza, Angel Garcia-Raso, Juan J Fiol, Miquel Barcelo-Oliver, Elies Molins, Antonio Frontera
The synthesis of a metalled double-helix containing exclusively silver-mediated C*-C* base pairs is reported herein (C* = N1hexylcytosine). Remarkably, it is the first crystal structure containing infinite and consecutive C*-AgI-C* base pairs that form a double helix. The AgI ion occupies the center between two C* residues with N(3)-Ag bond distances of 2.1 Å and short AgI-AgI distances (3.1 Å) suggesting an interesting argentophilic attraction as a stabilization source of the helical disposition. The solid state structure is further stabilized by metal-mediated base-pairs, hydrogen bonding and π-stacking interactions...
December 7, 2016: Chemistry: a European Journal
Natarajan Karikalan, Chelladurai Karuppiah, Shen-Ming Chen, Murugan Velmurugan, Periyasami Gnanaprakasam
Sodium ion hybrid supercapacitors are the potential energy storage devices and recently received an enormous interest. However, the development of desired cathode material and the use of non-aqueous electrolyte remains a great challenge. Hence, we developed the aqueous Na-ion hybrid supercapacitor based on three dimensional fibrous network of NaMnO2. The described cathode material was synthesized by the electro-oxidation of potassium manganese hexacyanoferrate (KMnHCF) nanocubes. The oxidized compound was confirmed as Na0...
December 7, 2016: Chemistry: a European Journal
Arnab Mukherjee, Joseph Hawthorne, Jason C White, Jason W Kelsey
Although the use of engineered nanomaterials continues to increase, an understanding of how these materials interact with co-existing contaminants in the environment is largely unknown. Here, the effect of Ag in bulk, ionic, and nanoparticle (NP; bare and polyvinyl pyrrolidone coated) form at 3 concentrations (0, 500, 1000, 2000 mg/kg; ion at 69, 138, 276 mg/kg) on the accumulation of field weathered chlordane and dichlorodiphenyldichloroethylene + metabolites (DDX) by Eisenia fetida (earthworm) was investigated...
December 7, 2016: Environmental Toxicology and Chemistry
Max Herzog, Dennis Konnerup, Ole Pedersen, Anders Winkel, Timothy David Colmer
Floods and salinization of agricultural land adversely impact global rice production. We investigated whether gas films on leaves of submerged rice delay salt entry during saline submergence. Two-week-old plants with leaf gas films (+GF) or with gas films experimentally removed (-GF) were submerged in artificial floodwater with 0 or 50 mM NaCl for up to 16 d. Gas films were present > 9 d on + GF plants after which gas films were diminished. Tissue ion analysis (Na(+) , Cl(-) and K(+) ) showed that gas films caused some delay of Na(+) entry, as leaf Na(+) concentration was 36-42% higher in -GF leaves than + GF leaves on d 1-5...
December 7, 2016: Plant, Cell & Environment
Yan Li, Xin Chen, Rhonda Dzakpasu, Katherine Conant
Oscillatory activity occurs in cortical and hippocampal networks with specific frequency ranges thought to be critical to working memory, attention, differentiation of neuronal precursors, and memory trace replay. Synchronized activity within relatively large neuronal populations is influenced by firing and bursting frequency within individual cells, and the latter is modulated by changes in intrinsic membrane excitability and synaptic transmission. Published work suggests that dopamine (DA), a potent modulator of learning and memory, acts on dopamine receptor 1-like dopamine receptors (D1Rs) to influence the phosphorylation and trafficking of glutamate receptor subunits, along with long-term potentiation (LTP) of excitatory synaptic transmission in striatum and prefrontal cortex...
December 7, 2016: Journal of Neurochemistry
Peter Comba, Markus Enders, Michael Großhauser, Markus Hiller, Dennis Müller, Hubert Wadepohl
Reported are the syntheses, structures and magnetic properties, also by NMR spectroscopy in solution, of a series of 13 linear trinuclear 3d-4f compounds with a lanthanide(iii) surrounded by two Ni(II) ions, NiLn(III), where the central Ln(III) is hexacoordinate. For three of the crystal structures, an additional H2O molecule is coordinated to the central Ln(III) ion, leading to a monocapped trigonal prismatic structure. However, NMR spectroscopy indicates that in solution, these complexes also have a hexacoordinate Ln(III) center...
December 7, 2016: Dalton Transactions: An International Journal of Inorganic Chemistry
Kazim Gorgulu, Abdullah Gok, Mehmet Yilmaz, Kagan Topalli, Necmi Bıyıklı, Ali K Okyay
Absorbing infrared radiation efficiently is important for critical applications such as thermal imaging and infrared spectroscopy. Common infrared absorbing materials are not standard in Si VLSI technology. We demonstrate ultra-broadband mid-infrared absorbers based purely on silicon. Broadband absorption is achieved by the combined effects of free carrier absorption, and vibrational and plasmonic absorption resonances. The absorbers, consisting of periodically arranged silicon gratings, can be fabricated using standard optical lithography and deep reactive ion etching techniques, allowing for cost-effective and wafer-scale fabrication of micro-structures...
December 7, 2016: Scientific Reports
Wei-Guang Li, Ming-Gang Liu, Shining Deng, Yan-Mei Liu, Lin Shang, Jing Ding, Tsan-Ting Hsu, Qin Jiang, Ying Li, Fei Li, Michael Xi Zhu, Tian-Le Xu
Acid-sensing ion channel 1a (ASIC1a) has been shown to play important roles in synaptic plasticity, learning and memory. Here we identify a crucial role for ASIC1a in long-term depression (LTD) at mouse insular synapses. Genetic ablation and pharmacological inhibition of ASIC1a reduced the induction probability of LTD without affecting that of long-term potentiation in the insular cortex. The disruption of ASIC1a also attenuated the extinction of established taste aversion memory without altering the initial associative taste learning or its long-term retention...
December 7, 2016: Nature Communications
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