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https://www.readbyqxmd.com/read/28426983/constraining-the-temporal-variations-of-ra-isotopes-and-rn-in-the-groundwater-end-member-implications-for-derived-sgd-estimates
#1
Marc Cerdà-Domènech, Valentí Rodellas, Albert Folch, Jordi Garcia-Orellana
Submarine groundwater discharge (SGD) has been recognized as an important supplier of chemical compounds to the ocean that may influence coastal geochemical cycles. Radium isotopes ((223)Ra, (224)Ra, (226)Ra,(228)Ra) and radon ((222)Rn) have been widely applied as tracers of SGD. Their application requires the appropriate characterization of both the concentrations of tracers in the discharging groundwater and their distribution in the coastal water column. This study evaluates the temporal evolution of Ra isotopes and (222)Rn concentrations in a dynamic subterranean estuary of a microtidal Mediterranean coastal aquifer that experiences large displacements of the fresh-saltwater interface as a necessary initial step in evaluating the influence of SGD in coastal waters...
April 17, 2017: Science of the Total Environment
https://www.readbyqxmd.com/read/28424662/untangling-genomes-of-novel-planctomycetal-and-verrucomicrobial-species-from-monterey-bay-kelp-forest-metagenomes-by-refined-binning
#2
John Vollmers, Martinique Frentrup, Patrick Rast, Christian Jogler, Anne-Kristin Kaster
The kelp forest of the Pacific temperate rocky marine coastline of Monterey Bay in California is a dominant habitat for large brown macro-algae in the order of Laminariales. It is probably one of the most species-rich, structurally complex and productive ecosystems in temperate waters and well-studied in terms of trophic ecology. However, still little is known about the microorganisms thriving in this habitat. A growing body of evidence suggests that bacteria associated with macro-algae represent a huge and largely untapped resource of natural products with chemical structures that have been optimized by evolution for biological and ecological purposes...
2017: Frontiers in Microbiology
https://www.readbyqxmd.com/read/28424337/physical-and-chemical-gradients-in-the-tumor-microenvironment-regulate-tumor-cell-invasion-migration-and-metastasis
#3
Madeleine J Oudin, Valerie M Weaver
Cancer metastasis requires the invasion of tumor cells into the stroma and the directed migration of tumor cells through the stroma toward the vasculature and lymphatics where they can disseminate and colonize secondary organs. Physical and biochemical gradients that form within the primary tumor tissue promote tumor cell invasion and drive persistent migration toward blood vessels and the lymphatics to facilitate tumor cell dissemination. These microenvironment cues include hypoxia and pH gradients, gradients of soluble cues that induce chemotaxis, and ions that facilitate galvanotaxis, as well as modifications to the concentration, organization, and stiffness of the extracellular matrix that produce haptotactic, alignotactic, and durotactic gradients...
April 19, 2017: Cold Spring Harbor Symposia on Quantitative Biology
https://www.readbyqxmd.com/read/28419899/the-long-term-tsunami-impact-evolution-of-iron-speciation-and-major-elements-concentration-in-tsunami-deposits-from-thailand
#4
Lidia Kozak, Przemyslaw Niedzielski
The article describes the unique studies of the chemical composition changes of new geological object (tsunami deposits in south Thailand - Andaman Sea Coast) during four years (2005-2008) from the beginning of formation of it (deposition of tsunami transported material, 26 December 2004). The chemical composition of the acid leachable fraction of the tsunami deposits has been studied in the scope of concentration macrocompounds - concentration of calcium, magnesium, iron, manganese and iron speciation - the occurrence of Fe(II), Fe(III) and non-ionic iron species described as complexed iron (Fe complex)...
April 15, 2017: Chemosphere
https://www.readbyqxmd.com/read/28419340/extremely-thick-cell-walls-and-low-mesophyll-conductance-welcome-to-the-world-of-ancient-living
#5
Linda-Liisa Veromann-Jürgenson, Tiina Tosens, Lauri Laanisto, Ülo Niinemets
Mesophyll conductance is thought to be an important photosynthetic limitation in gymnosperms, but they currently constitute the most understudied plant group in regard to the extent to which photosynthesis and intrinsic water use efficiency are limited by mesophyll conductance. A comprehensive analysis of leaf gas exchange, photosynthetic limitations, mesophyll conductance (calculated by three methods previously used for across-species comparisons), and the underlying ultra-anatomical, morphological and chemical traits in 11 gymnosperm species varying in evolutionary history was performed to gain insight into the evolution of structural and physiological controls on photosynthesis at the lower return end of the leaf economics spectrum...
April 13, 2017: Journal of Experimental Botany
https://www.readbyqxmd.com/read/28419173/sponge-symbioses-between-xestospongia-deweerdtae-and-plakortis-spp-are-not-motivated-by-shared-chemical-defense-against-predators
#6
Micah Jaarsma Marty, Jan Vicente, Benjamin L Oyler, Allen Place, Russell T Hill
The recently described epizoic sponge-sponge symbioses between Xestospongia deweerdtae and two species of Plakortis present an unusual series of sponge interactions. Sponges from the genus Plakortis are fierce allelopathic competitors, rich in cytotoxic secondary metabolites, and yet X. deweerdtae flourishes as an epizoic encrustation on Plakortis deweerdtaephila and Plakortis symbiotica. Our objective in this study was to evaluate the hypothesis that X. deweerdtae grows epizoic to these two species of Plakortis due to a shared chemical defense against predators...
2017: PloS One
https://www.readbyqxmd.com/read/28415520/tuneable-hydrolytic-degradation-of-poly-l-lactide-scaffolds-triggered-by-zno-nanoparticles
#7
Erlantz Lizundia, Paula Mateos, José Luis Vilas
In this work we fabricate porous PLLA and PLLA/ZnO scaffolds with porosities ranging from 10 to 90% and average pore diameter of 125-250μm by solvent casting/particulate leaching method. The structural evolution of PLLA/ZnO scaffolds during their in vitro degradation in phosphate buffered saline (PBS) at physiological pH (7.4) has been studied as a function of porosity and obtained results were compared to plain PLLA scaffolds. The changes induced upon the hydrolytic degradation of scaffolds have been explored by measuring the pH changes of the medium, the mass loss, thermal transitions, crystalline structure, thermal stability and the morphological changes...
June 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
https://www.readbyqxmd.com/read/28415293/two-component-dark-bright-solitons-in-three-dimensional-atomic-bose-einstein-condensates
#8
Wenlong Wang, P G Kevrekidis
In the present work, we revisit two-component Bose-Einstein condensates in their fully three-dimensional (3D) form. Motivated by earlier studies of dark-bright solitons in the 1D case, we explore the stability of these structures in their fully 3D form in two variants. In one the dark soliton is planar and trapping a planar bright (disk) soliton. In the other case, a dark spherical shell soliton creates an effective potential in which a bright spherical shell of atoms is trapped in the second component. We identify these solutions as numerically exact states (up to a prescribed accuracy) and perform a Bogolyubov-de Gennes linearization analysis that illustrates that both structures can be dynamically stable in suitable intervals of sufficiently low chemical potentials...
March 2017: Physical Review. E
https://www.readbyqxmd.com/read/28415230/scale-invariant-puddles-in-graphene-geometric-properties-of-electron-hole-distribution-at-the-dirac-point
#9
M N Najafi, M Ghasemi Nezhadhaghighi
We characterize the carrier density profile of the ground state of graphene in the presence of particle-particle interaction and random charged impurity in zero gate voltage. We provide detailed analysis on the resulting spatially inhomogeneous electron gas, taking into account the particle-particle interaction and the remote Coulomb disorder on an equal footing within the Thomas-Fermi-Dirac theory. We present some general features of the carrier density probability measure of the graphene sheet. We also show that, when viewed as a random surface, the electron-hole puddles at zero chemical potential show peculiar self-similar statistical properties...
March 2017: Physical Review. E
https://www.readbyqxmd.com/read/28414434/ammonia-activation-h2-evolution-and-nitride-formation-from-a-molybdenum-complex-with-a-chemically-and-redox-non-innocent-ligand
#10
Grant W Margulieux, Mate J Bezdek, Zoë R Turner, Paul J Chirik
Treatment of the bis(imino)pyridine molybdenum η6-benzene complex (iPrPDI)Mo(η6-C6H6) (iPrPDI, 2,6-(2,6-iPr2C6H3N=CMe)2C5H3N) with NH3 resulted in coordination in-duced haptotropic rearrangement of the arene to form (iPrPDI)Mo(NH3)2(η2-C6H6). Analogous η2-ethylene and η2-cyclohexene complexes were also synthesized and the latter crystallo-graphically characterized. All three compounds undergo loss of the η2-coordinated ligand followed by N-H bond activation, bis(imino)pyridine modification and H2 loss...
April 17, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28409427/environment-polluting-conventional-chemical-control-compared-to-an-environmentally-friendly-ipm-approach-for-control-of-diamondback-moth-plutella-xylostella-l-in-china-a-review
#11
Muhammad Shakeel, Muhammad Farooq, Wajid Nasim, Waseem Akram, Fawad Zafar Ahmad Khan, Waqar Jaleel, Xun Zhu, Haichen Yin, Shuzhong Li, Shah Fahad, Saddam Hussain, Bhagirath Singh Chauhan, Fengliang Jin
The diamondback moth, Plutella xylostella, is recognized as a widely distributed destructive insect pest of Brassica worldwide. The management of this pest is a serious issue, and an estimated annual cost of its management has reached approximately US$4 billion. Despite the fact that chemicals are a serious threat to the environment, lots of chemicals are applied for controlling various insect pests especially P. xylostella. An overreliance on chemical control has not only led to the evolution of resistance to insecticides and to a reduction of natural enemies but also has polluted various components of water, air, and soil ecosystem...
April 13, 2017: Environmental Science and Pollution Research International
https://www.readbyqxmd.com/read/28408315/the-corr-hypothesis-for-genes-in-organelles
#12
John F Allen
Chloroplasts and mitochondria perform energy transduction in photosynthesis and respiration. These processes can be described in physico-chemical terms with no obvious requirement for co-located genetic systems, separated from those of the rest of the cell. Accordingly, biochemists once tended to regard endosymbiosis as untestable evolutionary speculation. Lynn Sagan's seminal 1967 paper "On the Origin of Mitosing Cells" outlined the evolution of eukaryotic cells by endosymbiosis of prokaryotes. The endosymbiont hypothesis is consistent with presence of DNA in chloroplasts and mitochondria, but does not assign it a function...
April 10, 2017: Journal of Theoretical Biology
https://www.readbyqxmd.com/read/28407390/enantioselective-chemo-and-biocatalysis-partners-in-retrosynthesis
#13
Erick Moran Carreira, Nicholas Turner, Moritz Hönig, Philipp Sondermann
Recent developments of biocatalytic and chemocata-lytic methods are discussed. The review provides a guide to the use of biocatalytic methods in the area of chemical synthesis with focused attention on retrosynthetic considerations and analysis. The methods presented are organized according to bond disconnections and attendant synthetic methods. The review is expected to lead to better understanding of the charac-teristics and distinctions of the two complementary approaches. It depicts for researchers in bio- and chemocatalysis a road map of challenges and opportunities for the evolution (and at times revolution) in chemical synthesis...
April 13, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28407240/evolution-of-taste-compounds-of-dezhou-braised-chicken-during-cooking-evaluated-by-chemical-analysis-and-an-electronic-tongue-system
#14
Dengyong Liu, Shengjie Li, Nan Wang, Yajun Deng, Lei Sha, Shengmei Gai, Huan Liu, Xinglian Xu
This paper aimed to study the time course changes in taste compounds of Dezhou-braised chicken during the entire cooking process mainly consisting of deep-frying, high-temperature boiling, and low-temperature braising steps. For this purpose, meat samples at different processing stages were analyzed for 5'-nucleotides and free amino acids, and were also subjected to electronic tongue measurements. Results showed that IMP, Glu, Lys, and sodium chloride were the main compounds contributing to the taste attributes of the final product...
April 13, 2017: Journal of Food Science
https://www.readbyqxmd.com/read/28406299/discovery-and-optimization-of-isoquinoline-ethyl-ureas-as-antibacterial-agents
#15
Philippe Panchaud, Thierry Bruyère, Anne-Catherine Blumstein, Daniel Bur, Alain Chambovey, Eric A Ertel, Markus Gude, Christian Hubschwerlen, Loïc Jacob, Thierry Kimmerlin, Thomas Pfeifer, Lars Prade, Peter Seiler, Daniel Ritz, Georg Rueedi
Our strategy to combat resistant bacteria consisted in targeting the GyrB/ParE ATP-binding sites located on bacterial DNA gyrase and topoisomerase IV and not utilized by marketed antibiotics. Screening around the minimal ethyl urea binding motif led to the identification of isoquinoline ethyl urea 13 as promising starting point for fragment evolution. The optimization was guided by structure-based design and focused on antibacterial activity in vitro and in vivo, culminating in the discovery of unprecedented substituents able to interact with conserved residues within the ATP-binding site...
April 13, 2017: Journal of Medicinal Chemistry
https://www.readbyqxmd.com/read/28406150/one-step-assembly-of-2h-1t-mos2-cu-reduced-graphene-oxide-nanosheets-for-highly-efficient-hydrogen-evolution
#16
H-Y He
The transition metal dichagenides and their metallic 1T structure are attracting contemporary attentions for applications in high-performance devices because their peculiar optical and electrical properties. The single and few layers 1T structure is generally obtained by mechanical or chemical exfoliation. This work presents facile one-step synthesis of 2H-1T MoS2:Cu/reduced graphene oxide nanosheets. The experiment results indicated that the MoS2 and MoS2:Cu prepared by simple chemical solution reaction possessed 2H-1T structures...
April 13, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28403162/maintaining-extensivity-in-evolutionary-multiplex-networks
#17
Chris G Antonopoulos, Murilo S Baptista
In this paper, we explore the role of network topology on maintaining the extensive property of entropy. We study analytically and numerically how the topology contributes to maintaining extensivity of entropy in multiplex networks, i.e. networks of subnetworks (layers), by means of the sum of the positive Lyapunov exponents, HKS, a quantity related to entropy. We show that extensivity relies not only on the interplay between the coupling strengths of the dynamics associated to the intra (short-range) and inter (long-range) interactions, but also on the sum of the intra-degrees of the nodes of the layers...
2017: PloS One
https://www.readbyqxmd.com/read/28402654/control-of-ligand-pka-values-tunes-the-electrocatalytic-dihydrogen-evolution-mechanism-in-a-redox-active-aluminum-iii-complex
#18
Tobias J Sherbow, James C Fettinger, Louise A Berben
Redox-active ligands bring electron- and proton-transfer reactions to main-group coordination chemistry. In this Forum Article, we demonstrate how ligand pKa values can be used in the design of a reaction mechanism for a ligand-based electron- and proton-transfer pathway, where the ligand retains a negative charge and enables dihydrogen evolution. A bis(pyrazolyl)pyridine ligand, (iPr)Pz2P, reacts with 2 equiv of AlCl3 to afford [((iPr)Pz2P)AlCl2(THF)][AlCl4] (1). A reaction involving two-electron reduction and single-ligand protonation of 1 affords [((iPr)HPz2P(-))AlCl2] (2), where each of the electron- and proton-transfer events is ligand-centered...
April 12, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28398435/composition-and-phase-controlled-synthesis-and-applications-of-alloyed-phase-heterostructures-of-transition-metal-disulphides
#19
Kai Yang, Xiaoshan Wang, Hai Li, Bo Chen, Xiao Zhang, Shaozhou Li, Ning Wang, Hua Zhang, Xiao Huang, Wei Huang
The facile tuning of the composition and structures of two-dimensional (2D) transition metal dichalcogenide (TMD) nanosheets is essential for improving their performance in various applications, but remains difficult to realize via a direct solution process. Here, we report the one-step liquid-phase preparation of alloyed Mo1-χWχS2 nanosheets with tunable 1T/2H phase ratios. These alloyed nanosheets showed composition- and phase-dependent electrochemical and electronic properties. By tuning the Mo/W ratio, an optimized combination of high-density active sites for the hydrogen evolution reaction (HER) and low charge transfer resistance can be achieved...
April 20, 2017: Nanoscale
https://www.readbyqxmd.com/read/28398197/emergence-and-evolution-of-an-interaction-between-intrinsically-disordered-proteins
#20
Greta Hultqvist, Emma Åberg, Carlo Camilloni, Gustav N Sundell, Eva Andersson, Jakob Dogan, Celestine N Chi, Michele Vendruscolo, Per Jemth
Protein-protein interactions involving intrinsically disordered proteins are important for cellular function and common in all organisms. However, it is not clear how such interactions emerge and evolve on a molecular level. We performed phylogenetic reconstruction, resurrection and biophysical characterization of two interacting disordered protein domains, CID and NCBD. CID appeared after the divergence of protostomes and deuterostomes 450-600 million years ago, while NCBD was present in the protostome/deuterostome ancestor...
April 11, 2017: ELife
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