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Sample records for surface active molecules

  1. c-Met and Other Cell Surface Molecules: Interaction, Activation and Functional Consequences

    Directory of Open Access Journals (Sweden)

    Giuditta Viticchiè

    2015-01-01

    Full Text Available The c-Met receptor, also known as the HGF receptor, is one of the most studied tyrosine kinase receptors, yet its biological functions and activation mechanisms are still not fully understood. c-Met has been implicated in embryonic development and organogenesis, in tissue remodelling homeostasis and repair and in cancer metastasis. These functions are indicative of the many cellular processes in which the receptor plays a role, including cell motility, scattering, survival and proliferation. In the context of malignancy, sustained activation of c-Met leads to a signalling cascade involving a multitude of kinases that initiate an invasive and metastatic program. Many proteins can affect the activation of c-Met, including a variety of other cell surface and membrane-spanning molecules or receptors. Some cell surface molecules share structural homology with the c-Met extracellular domain and can activate c-Met via clustering through this domain (e.g., plexins, whereas other receptor tyrosine kinases can enhance c-Met activation and signalling through intracellular signalling cascades (e.g., EGFR. In this review, we provide an overview of c-Met interactions and crosstalk with partner molecules and the functional consequences of these interactions on c-Met activation and downstream signalling, c-Met intracellular localization/recycling and c-Met degradation.

  2. Mobility of chemisorbed molecules and surface regeneration of active centers during dehydration of isopropanol on aluminium oxide and aluminosilicate

    International Nuclear Information System (INIS)

    Makhlis, L.A.; Vasserberg, V.Eh.

    1976-01-01

    By a differential isotope method involving 14 C the authors have investigated the surface mobility of chemisorbed molecules of isopropanol during its dehydration in an adsorption layer on aluminium oxide and aluminosilicate. The chemisorbed alcohol molecules possess marked surface mobility which plays a decisive part in the mechanism of surface regeneration of the active catalyst centers in the process of dehydration. The cessation of the reaction long before the adsorbed alcohol is completely used up is explained by the hypothesis that there is local overpopulation of the active sectors by water formed by the reaction; this hinders further surface regeneration and repetition of the elementary events of dehydration

  3. Understanding the adsorption behavior of surface active molecules on ZnO nanostructures by experimental and first-principles calculations.

    Science.gov (United States)

    Singh, Baljinder; Singh, Satvinder; Singh, Janpreet; Saini, G S S; Mehta, D S; Singh, Gurinder; Tripathi, S K; Kaura, Aman

    2015-11-11

    Zinc oxide (ZnO) nanostructures with different morphologies are prepared in the presence of surface active molecules such as sodium dodecyl sulphate (SDS), Tween 80 and Triton X-100 by a chemical method. The experimental and first principles methods are employed to understand the microscopic origin of the asymmetric growth mechanism of ZnO in the presence of various surface active molecules. Effect of increase in the amount of surface active molecules and temperature is studied on the growth morphology of ZnO. An innovative method is developed to synthesize ZnO nanowires (NWs) in the presence of SDS. Spherical nanoparticles (NPs) to spherical clusters are obtained in the presence of Triton X-100 and Tween 80. These results are then supported by first principles calculations. The adsorption of the -OH functional group on both polar and nonpolar surfaces of ZnO is modelled by using density functional theory (DFT). The calculated binding energy (BE) is almost equivalent on both the surfaces with no preference on any particular surface. The calculated value of BE shows that the -OH group is physio-adsorbed on both the surfaces. This results in the spherical morphology of nanoparticles prepared in the presence of Tween 80. Bader charge analysis shows that the charge transfer mainly takes place on top two layers of the ZnO(101[combining macron]0) surface. The absence of high values of electron localization function (ELF) reflects the lack of covalent bonding between the -OH group and the ZnO(101[combining macron]0) surface.

  4. Influence of the water molecules near surface of viral protein on virus activation process

    Energy Technology Data Exchange (ETDEWEB)

    O, Shepelenko S; S, Salnikov A; V, Rak S; P, Goncharova E; B, Ryzhikov A, E-mail: shep@vector.nsc.r, E-mail: shep@ngs.r [Federal State Research Institution State Research Center of Virology and Biotechnology VECTOR of the Federal Service for Surveillance in Consumer Rights Protection and Human Well-being (FSRI SRC VB VECTOR) Koltsovo, Novosibirsk Region (Russian Federation)

    2009-06-01

    The infection of a cell with influenza virus comprises the stages of receptor binding to the cell membrane, endocytosis of virus particle, and fusion of the virus envelope and cell endosome membrane, which is determined by the conformational changes in hemagglutinin, a virus envelope protein, caused by pH decrease within the endosome. The pH value that induces conformation rearrangements of hemagglutinin molecule considerably varies for different influenza virus strains, first and foremost, due to the differences in amino acid structure of the corresponding proteins. The main goal of this study was to construct a model making it possible to assess the critical pH value characterizing the fusogenic activity of influenza virus hemagglutinin from the data on hemagglutinin structure and experimental verification of this model. Under this model, we assume that when the electrostatic force between interacting hemagglutinin molecules in the virus envelop exceeds a certain value, the hemagglutinin HA1 subunits are arranged so that they form a cavity sufficient for penetration of water molecules. This event leads to an irreversible hydration of the inner fragments of hemagglutinin molecule in a trimer and to the completion of conformational changes. The geometry of electrostatic field in hemagglutinin trimer was calculated taking into account the polarization effects near the interface of two dielectrics, aqueous medium and protein macromolecule. The critical pH values for the conformational changes in hemagglutinin were measured by the erythrocyte hemolysis induced by influenza virus particles when decreasing pH. The critical pH value conditionally separating the pH range into the regions with and without the conformational changes was calculated for several influenza virus H1N1 and H3N2 strains based on the data on the amino acid structure of the corresponding hemagglutinin molecules. Comparison of the theoretical and experimental values of critical pH values for

  5. Influence of the water molecules near surface of viral protein on virus activation process

    International Nuclear Information System (INIS)

    O, Shepelenko S; S, Salnikov A; V, Rak S; P, Goncharova E; B, Ryzhikov A

    2009-01-01

    The infection of a cell with influenza virus comprises the stages of receptor binding to the cell membrane, endocytosis of virus particle, and fusion of the virus envelope and cell endosome membrane, which is determined by the conformational changes in hemagglutinin, a virus envelope protein, caused by pH decrease within the endosome. The pH value that induces conformation rearrangements of hemagglutinin molecule considerably varies for different influenza virus strains, first and foremost, due to the differences in amino acid structure of the corresponding proteins. The main goal of this study was to construct a model making it possible to assess the critical pH value characterizing the fusogenic activity of influenza virus hemagglutinin from the data on hemagglutinin structure and experimental verification of this model. Under this model, we assume that when the electrostatic force between interacting hemagglutinin molecules in the virus envelop exceeds a certain value, the hemagglutinin HA1 subunits are arranged so that they form a cavity sufficient for penetration of water molecules. This event leads to an irreversible hydration of the inner fragments of hemagglutinin molecule in a trimer and to the completion of conformational changes. The geometry of electrostatic field in hemagglutinin trimer was calculated taking into account the polarization effects near the interface of two dielectrics, aqueous medium and protein macromolecule. The critical pH values for the conformational changes in hemagglutinin were measured by the erythrocyte hemolysis induced by influenza virus particles when decreasing pH. The critical pH value conditionally separating the pH range into the regions with and without the conformational changes was calculated for several influenza virus H1N1 and H3N2 strains based on the data on the amino acid structure of the corresponding hemagglutinin molecules. Comparison of the theoretical and experimental values of critical pH values for

  6. Surface enhanced Raman optical activity of molecules on orientationally averaged substrates: theory of electromagnetic effects.

    Science.gov (United States)

    Janesko, Benjamin G; Scuseria, Gustavo E

    2006-09-28

    We present a model for electromagnetic enhancements in surface enhanced Raman optical activity (SEROA) spectroscopy. The model extends previous treatments of SEROA to substrates, such as metal nanoparticles in solution, that are orientationally averaged with respect to the laboratory frame. Our theoretical treatment combines analytical expressions for unenhanced Raman optical activity with molecular polarizability tensors that are dressed by the substrate's electromagnetic enhancements. We evaluate enhancements from model substrates to determine preliminary scaling laws and selection rules for SEROA. We find that dipolar substrates enhance Raman optical activity (ROA) scattering less than Raman scattering. Evanescent gradient contributions to orientationally averaged ROA scale to first or higher orders in the gradient of the incident plane-wave field. These evanescent gradient contributions may be large for substrates with quadrupolar responses to the plane-wave field gradient. Some substrates may also show a ROA contribution that depends only on the molecular electric dipole-electric dipole polarizability. These conclusions are illustrated via numerical calculations of surface enhanced Raman and ROA spectra from (R)-(-)-bromochlorofluoromethane on various model substrates.

  7. HIV Aspartic Peptidase Inhibitors Modulate Surface Molecules and Enzyme Activities Involved with Physiopathological Events in Fonsecaea pedrosoi

    Directory of Open Access Journals (Sweden)

    Vanila F. Palmeira

    2017-05-01

    Full Text Available Fonsecaea pedrosoi is the main etiological agent of chromoblastomycosis, a recalcitrant disease that is extremely difficult to treat. Therefore, new chemotherapeutics to combat this fungal infection are urgently needed. Although aspartic peptidase inhibitors (PIs currently used in the treatment of human immunodeficiency virus (HIV have shown anti-F. pedrosoi activity their exact mechanisms of action have not been elucidated. In the present study, we have investigated the effects of four HIV-PIs on crucial virulence attributes expressed by F. pedrosoi conidial cells, including surface molecules and secreted enzymes, both of which are directly involved in the disease development. In all the experiments, conidia were treated with indinavir, nelfinavir, ritonavir and saquinavir (100 μM for 24 h, and then fungal cells were used to evaluate the effects of HIV-PIs on different virulence attributes expressed by F. pedrosoi. In comparison to untreated controls, exposure of F. pedrosoi cells to HIV-PIs caused (i reduction on the conidial granularity; (ii irreversible surface ultrastructural alterations, such as shedding of electron dense and amorphous material from the cell wall, undulations/invaginations of the plasma membrane with and withdrawal of this membrane from the cell wall; (iii a decrease in both mannose-rich glycoconjugates and melanin molecules and an increase in glucosylceramides on the conidial surface; (iv inhibition of ergosterol and lanosterol production; (v reduction in the secretion of aspartic peptidase, esterase and phospholipase; (vi significant reduction in the viability of non-pigmented conidia compared to pigmented ones. In summary, HIV-PIs are efficient drugs with an ability to block crucial biological processes of F. pedrosoi and can be seriously considered as potential compounds for the development of new chromoblastomycosis chemotherapeutics.

  8. Single Molecule Instrument for Surface Enhanced Raman Optical Activity of Biomolecules Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Stereochemistry is an essential element of our organic life. Only certain enantiomers are useful as drugs for the human body. Raman Optical Activity (ROA) and...

  9. Single Molecule Instrument for Surface Enhanced Raman Optical Activity of Biomolecules, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — Stereochemistry is an essential element of our organic life. Only certain enantiomers are useful as drugs for the human body. Raman optical activity (ROA) provides...

  10. Single Molecule Instrument for Surface Enhanced Raman Optical Activity of Biomolecules, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Stereochemistry is an essential element of our organic life. Only certain enantiomers are useful as drugs for the human body. Raman Optical Activity (ROA) and...

  11. Dynamics of Activated Molecules

    Energy Technology Data Exchange (ETDEWEB)

    Mullin, Amy S. [Univ. of Maryland, College Park, MD (United States)

    2016-11-16

    Experimental studies have been performed to investigate the collisional energy transfer processes of gas-phase molecules that contain large amounts of internal energy. Such molecules are prototypes for molecules under high temperature conditions relevant in combustion and information about their energy transfer mechanisms is needed for a detailed understanding and modeling of the chemistry. We use high resolution transient IR absorption spectroscopy to measure the full, nascent product distributions for collisions of small bath molecules that relax highly vibrationally excited pyrazine molecules with E=38000 cm-1 of vibrational energy. To perform these studies, we developed new instrumentation based on modern IR light sources to expand our experimental capabilities to investigate new molecules as collision partners. This final report describes our research in four areas: the characterization of a new transient absorption spectrometer and the results of state-resolved collision studies of pyrazine(E) with HCl, methane and ammonia. Through this research we have gained fundamental new insights into the microscopic details of relatively large complex molecules at high energy as they undergo quenching collisions and redistribute their energy.

  12. Modelling of energetic molecule-surface interactions

    International Nuclear Information System (INIS)

    Kerford, M.

    2000-09-01

    This thesis contains the results of molecular dynamics simulations of molecule-surface interactions, looking particularly at fullerene molecules and carbon surfaces. Energetic impacts of fullerene molecules on graphite create defect craters. The relationship between the parameters of the impacting molecule and the parameters of the crater axe examined and found to be a function of the energy and velocity of the impacting molecule. Less energetic fullerene molecules can be scattered from a graphite surface and the partitioning of energy after a scattering event is investigated. It is found that a large fraction of the kinetic energy retained after impact is translational energy, with a small fraction of rotational energy and a number of vibrational modes. At impact energies where the surface is not broken and at normal incidence, surface waves axe seen to occur. These waves axe used to develop a method of desorbing molecules from a graphite surface without damage to either the surface or the molecules being desorbed. A number of fullerene molecules are investigated and ways to increase the desorption yield are examined. It is found that this is a successful technique for desorbing large numbers of intact molecules from graphite. This technique could be used for desorbing intact molecules into a gas phase for mass spectrometric analysis. (author)

  13. Coaggregation of the T-cell receptor with CD4 and other T-cell surface molecules enhances T-cell activation

    DEFF Research Database (Denmark)

    Owens, T; Fazekas de St Groth, B; Miller, J F

    1987-01-01

    and the TCR to stabilize TCR complexes and so to enhance T-cell activation. A related but less specific accessory role for other T-cell surface molecules is also suggested. We propose that the cellular interaction that leads to physiological T-cell activation not only achieves TCR ligation but also promotes......The CD4 molecule, expressed by T cells restricted by class II major histocompatibility complex (MHC) molecules, is believed to play a role in T-cell activation. We have previously suggested that CD4 interacts with the T-cell receptor for antigen (TCR) and with class II MHC and that this dual...... interaction stabilizes the bond between the TCR and antigen in association with MHC. To investigate the contribution of CD4-TCR interaction, we have used the murine monoclonal anti-TCR V beta 8 antibody F23.1 to activate cloned T cells. Weak activation by soluble biotinylated F23.1 was markedly enhanced...

  14. Electrocatalytic activation of small molecules

    OpenAIRE

    Liu, YuPing

    2017-01-01

    Electrochemsitry and electrocatalysis are useful techniques for energy conversion and energy storage applications. In this project, the electrocatalytic activation of small molecules, H₂O, methanol and ethanol, and CO₂, has been studied as potential methods for energy storage and conversion. A hexaniobate Lindqvist ion assisted Co and Ni nanostructure deposition method has been developed. Efficient catalytic activity towards water oxidation has been observed with high TOF values obtained ...

  15. A study on the influence of surface active agent molecules on the AFM scanning and imaging of SWCNTs

    Energy Technology Data Exchange (ETDEWEB)

    Xu Ke; Yu Haibo; Tian Xiaojun; Dong Zaili [State Key Laboratory of Robotics, Shenyang Institute of Automation, CAS, Shenyang 110016 (China); Wu Chengdong [Northeastern University, Shenyang 110004 (China)], E-mail: xuke08@sia.cn

    2009-09-01

    The paper proposed a preprocessing method for scanning samples based on rinsing technology, and solved the effective fabrication problem of AFM scanning samples based on facilitated dispersing SWCNTs with SDS surface active agents. First, the ultrasonication oscillation method was applied, and the uniform alignment of SWCNTs in SDS was realized. Then, SDS solution of different concentrations was scanned and imaged with AFM, the influence of SDS solution on the imaging quality of SWCNTs was analyzed, and the method to effectively fabricate scanning samples after dispersing SWCNTs was found. The results of the experiments showed that the preprocessing of the SWCNTs solution scanning samples was the decisive factor to influence SWCNTs imaging quality, that the result of rinsing SWCNTs scanning samples for 5s at 0.1ml/s with di-ionized water was the best, and that with the same rinsing rate and angle, the rinsing di-ionized water quantity would influence the alignment degree of SWCNTs on the substrates and SDS macromolecules' residual quantity on SWCNTs scanning samples.

  16. A study on the influence of surface active agent molecules on the AFM scanning and imaging of SWCNTs

    International Nuclear Information System (INIS)

    Xu Ke; Yu Haibo; Tian Xiaojun; Dong Zaili; Wu Chengdong

    2009-01-01

    The paper proposed a preprocessing method for scanning samples based on rinsing technology, and solved the effective fabrication problem of AFM scanning samples based on facilitated dispersing SWCNTs with SDS surface active agents. First, the ultrasonication oscillation method was applied, and the uniform alignment of SWCNTs in SDS was realized. Then, SDS solution of different concentrations was scanned and imaged with AFM, the influence of SDS solution on the imaging quality of SWCNTs was analyzed, and the method to effectively fabricate scanning samples after dispersing SWCNTs was found. The results of the experiments showed that the preprocessing of the SWCNTs solution scanning samples was the decisive factor to influence SWCNTs imaging quality, that the result of rinsing SWCNTs scanning samples for 5s at 0.1ml/s with di-ionized water was the best, and that with the same rinsing rate and angle, the rinsing di-ionized water quantity would influence the alignment degree of SWCNTs on the substrates and SDS macromolecules' residual quantity on SWCNTs scanning samples.

  17. Energy redistribution in diatomic molecules on surfaces

    International Nuclear Information System (INIS)

    Asscher, M.; Somorjai, G.A.

    1984-04-01

    Translational and internal degrees of freedom of a scattered beam of NO molecules from a Pt(111) single crystal surface were measured as a function of scattering angle and crystal temperature in the range 450 to 1250K. None of the three degrees of freedom were found to fully accommodate to the crystal temperature, the translational degree being the most accommodated and the rotational degree of freedom the least. A precursor state model is suggested to account for the incomplete accommodation of translational and vibrational degrees of freedom as a function of crystal temperature and incident beam energy. The vibrational accommodation is further discussed in terms of a competition between desorption and vibrational excitation processes, thus providing valuable information on the interaction between vibrationally excited molecules and surfaces. Energy transfer into rotational degrees of freedom is qualitatively discussed

  18. Bonding and interaction of molecules with surfaces

    International Nuclear Information System (INIS)

    Ellis, D.E.

    1988-01-01

    In this lecture it is intended to discuss some general features of bonding and interaction of molecules with surfaces. The geometry of surface complexes is sufficiently difficult and the interaction mechanisms are sufficiently subtle. That all possible theoretical models need to be exploited such as: i) Semiempirical - including Huckel molecular orbital theory; ii)first principles including self-consistent-field Hartree-Fock and Local Density approaches; iii)explicitly correlated, including C.I., Generalized Valence Bond, Coupled Cluster Perturbation Theory and Many Body Perturbation Theory. (A.C.A.S.) [pt

  19. Cloning and expression of the receptor for human urokinase plasminogen activator, a central molecule in cell surface, plasmin dependent proteolysis

    DEFF Research Database (Denmark)

    Roldan, A.L.; Cubellis, M.V.; Masucci, M.T.

    1990-01-01

    , and therefore the capacity of cells to migrate and invade neighboring tissues. We have isolated a 1.4 kb cDNA clone coding for the entire human uPAR. An oligonucleotide synthesized on the basis of the N-terminal sequence of the purified protein was used to screen a cDNA library made from SV40 transformed human......, a size very close to that of the cloned cDNA. Expression of the uPAR cDNA in mouse cells confirms that the clone is complete and expresses a functional uPA binding protein, located on the cell surface and with properties similar to the human uPAR. Caseinolytic plaque assay, immunofluorescence analysis...... fibroblasts [Okayama and Berg (1983) Mol. Cell Biol., 3, 280-289]. The cDNA encodes a protein of 313 amino acids, preceded by a 21 residue signal peptide. A hydrophobicity plot suggests the presence of a membrane spanning domain close to the C-terminus. The cDNA hybridizes to a 1.4 kb mRNA from human cells...

  20. Orientating lipase molecules through surface chemical control for enhanced activity: A QCM-D and ToF-SIMS investigation.

    Science.gov (United States)

    Joyce, Paul; Kempson, Ivan; Prestidge, Clive A

    2016-06-01

    Bio-active materials consisting of lipase encapsulated within porous silica particles were engineered to control the adsorption kinetics and molecular orientation of lipase, which play critical roles in the digestion kinetics of triglycerides. The adsorption kinetics of Candida antartica lipase A (CalA) was monitored using quartz crystal microbalance with dissipation (QCM-D) and controlled by altering the hydrophobicity of a silica binding support. The extent of adsorption was 2-fold greater when CalA was adsorbed onto hydrophobic silica compared to hydrophilic silica. Time-of-flight secondary ion mass spectrometry (ToF-SIMS) fragmentation patterns, in conjunction with multivariate statistics, demonstrated enhanced exposure of the lipase's catalytic domain, specifically the histidine group responsible for activity, when CalA was adsorbed on hydrophilic silica. Consequently, lipid digestion kinetics were enhanced when CalA was loaded in hydrophilic porous silica particles, i.e., a 2-fold increase in the pseudo-first-order rate constant for digestion when compared to free lipase. In contrast, digestion kinetics were inhibited when CalA was hosted in hydrophobic porous silica, i.e., a 5-fold decrease in pseudo-first-order rate constant for digestion when compared to free lipase. These findings provide valuable insights into the mechanism of lipase action which can be exploited to develop smarter food and drug delivery systems consisting of porous lipid-based materials. Copyright © 2016 Elsevier B.V. All rights reserved.

  1. Leukocytes-depleting filters preferentially remove activated leukocytes and reduce the expression of surface adhesion molecules during the simulated extracorporeal circulation of human blood.

    Science.gov (United States)

    Alexiou, Christos; Sheppard, Stuart; Tang, Augustine; Rengarajan, Arvind; Smith, David; Haw, Marcus; Gibbs, Roz

    2006-01-01

    The effect of leukocyte-depleting filters on the total and activated leukocyte counts and the expression of surface adhesion molecules CD11b, CD18, and CD62L during the in vitro extracorporeal circulation of human blood was studied. A 200 ml blood sample was taken from 10 patients undergoing CABG surgery. The blood was circulated for 60 minutes within an experimental extracorporeal circuit. A leukocyte-depleting filter was attached in five circuits (filtered group). In five other circuits, no filter was used (controls). Total leukocyte counts were determined manually. Activated leukocytes were identified using nitroblue tetrazolium staining. The expression of CD11b, CD18, and CD62L was measured with flow cytometry. At 60 minutes, total leukocyte counts were reduced by 49% from the baseline values in the filtered group and 10% in the control group (p filtered group and increased by 116% in the control group (p filtered group, the expression of CD11b, CD18, and CD612L decreased by 60%, 21%, and 79%, respectively, and in the control group it increased by 24%, 6%, and 28% (p filters preferentially remove activated leukocytes and reduce the expression of CD11b, CD18, and CD62L during the in vitro extracorporeal circulation of human blood.

  2. Modeling adsorption and reactions of organic molecules at metal surfaces.

    Science.gov (United States)

    Liu, Wei; Tkatchenko, Alexandre; Scheffler, Matthias

    2014-11-18

    response effects enables reliable modeling of structure and stability for a broad class of organic molecules adsorbed on metal surfaces. This method was demonstrated to achieve quantitative accuracy for aromatic hydrocarbons (benzene, naphthalene, anthracene, and diindenoperylene), C60, and sulfur/oxygen-containing molecules (thiophene, NTCDA, and PTCDA) on close-packed and stepped metal surfaces, leading to an overall accuracy of 0.1 Å in adsorption heights and 0.1 eV in binding energies with respect to state-of-the-art experiments. An unexpected finding is that vdW interactions contribute more to the binding of strongly bound molecules on transition-metal surfaces than for molecules physisorbed on coinage metals. The accurate inclusion of vdW interactions also significantly improves tilting angles and adsorption heights for all the studied molecules, and can qualitatively change the potential-energy surface for adsorbed molecules with flexible functional groups. Activation barriers for molecular switches and reaction precursors are modified as well.

  3. Raman Optical Activity of Biological Molecules

    Science.gov (United States)

    Blanch, Ewan W.; Barron, Laurence D.

    Now an incisive probe of biomolecular structure, Raman optical activity (ROA) measures a small difference in Raman scattering from chiral molecules in right- and left-circularly polarized light. As ROA spectra measure vibrational optical activity, they contain highly informative band structures sensitive to the secondary and tertiary structures of proteins, nucleic acids, viruses and carbohydrates as well as the absolute configurations of small molecules. In this review we present a survey of recent studies on biomolecular structure and dynamics using ROA and also a discussion of future applications of this powerful new technique in biomedical research.

  4. Electrospray deposition of organic molecules on bulk insulator surfaces.

    Science.gov (United States)

    Hinaut, Antoine; Pawlak, Rémy; Meyer, Ernst; Glatzel, Thilo

    2015-01-01

    Large organic molecules are of important interest for organic-based devices such as hybrid photovoltaics or molecular electronics. Knowing their adsorption geometries and electronic structures allows to design and predict macroscopic device properties. Fundamental investigations in ultra-high vacuum (UHV) are thus mandatory to analyze and engineer processes in this prospects. With increasing size, complexity or chemical reactivity, depositing molecules by thermal evaporation becomes challenging. A recent way to deposit molecules in clean conditions is Electrospray Ionization (ESI). ESI keeps the possibility to work with large molecules, to introduce them in vacuum, and to deposit them on a large variety of surfaces. Here, ESI has been successfully applied to deposit triply fused porphyrin molecules on an insulating KBr(001) surface in UHV environment. Different deposition coverages have been obtained and characterization of the surface by in-situ atomic force microscopy working in the non-contact mode shows details of the molecular structures adsorbed on the surface. We show that UHV-ESI, can be performed on insulating surfaces in the sub-monolayer regime and to single molecules which opens the possibility to study a variety of complex molecules.

  5. Self-assembly patterning of organic molecules on a surface

    Energy Technology Data Exchange (ETDEWEB)

    Pan, Minghu; Fuentes-Cabrera, Miguel; Maksymovych, Petro; Sumpter, Bobby G.; Li, Qing

    2017-04-04

    The embodiments disclosed herein include all-electron control over a chemical attachment and the subsequent self-assembly of an organic molecule into a well-ordered three-dimensional monolayer on a metal surface. The ordering or assembly of the organic molecule may be through electron excitation. Hot-electron and hot-hole excitation enables tethering of the organic molecule to a metal substrate, such as an alkyne group to a gold surface. All-electron reactions may allow a direct control over the size and shape of the self-assembly, defect structures and the reverse process of molecular disassembly from single molecular level to mesoscopic scale.

  6. Reaction dynamics of small molecules at metal surfaces

    CERN Document Server

    Samson, P A

    1999-01-01

    directed angular distributions suggest the influence of a trapping mechanism, recombining molecules scattering through a molecularly adsorbed state, with a transition state of large d sub N sub N responsible for the product vibrational excitation. Although N sub 2 dissociation on Fe(100) forms a simple overlayer structure, on Fe(110), molecular chemisorption does not occur at or above room temperature and the sticking is extremely small (approx 10 sup - sup 6 to 10 sup - sup 7). Activated nitrogen bombardment can be used to prepare a 'surface nitride' with a structure related to the geometry of bulk Fe sub 4 N. Scanning tunnelling microscopy yields atomic scale features that cannot be explained by simple overlayers. It is proposed that the uppermost iron layer reconstructs to generate quasi-octahedral sites between the top two layers, with sub-surface nitrogen in these sites forming a model for the 'surface nitride' structure. The dissociation-desorption dynamics of D sub 2 upon the Sn/Pt(111) surface alloy a...

  7. Imaging prototypical aromatic molecules on insulating surfaces: a review

    Science.gov (United States)

    Hoffmann-Vogel, R.

    2018-01-01

    Insulating substrates allow for in-plane contacted molecular electronics devices where the molecule is in contact with the insulator. For the development of such devices it is important to understand the interaction of molecules with insulating surfaces. As substrates, ionic crystals such as KBr, KCl, NaCl and CaF2 are discussed. The surface energies of these substrates are small and as a consequence intrinsic properties of the molecules, such as molecule–molecule interaction, become more important relative to interactions with the substrates. As prototypical molecules, three variants of graphene-related molecules are used, pentacene, C60 and PTCDA. Pentacene is a good candidate for molecular electronics applications due to its high charge carrier mobility. It shows mainly an upright standing growth mode and the morphology of the islands is strongly influenced by dewetting. A new second flat-lying phase of the molecule has been observed. Studying the local work function using the Kelvin method reveals details such as line defects in the center of islands. The local work function differences between the upright-standing and flat-lying phase can only be explained by charge transfer that is unusual on ionic crystalline surfaces. C60 nucleation and growth is explained by loosely bound molecules at kink sites as nucleation sites. The stability of C60 islands as a function of magic numbers is investigated. Peculiar island shapes are obtained from unusual dewetting processes already at work during growth, where molecules ‘climb’ to the second molecular layer. PTCDA is a prototypical semiconducting molecule with strong quadrupole moment. It grows in the form of elongated islands where the top and the facets can be molecularly resolved. In this way the precise molecular arrangement in the islands is revealed.

  8. Surface functionalization of aluminosilicate nanotubes with organic molecules

    Directory of Open Access Journals (Sweden)

    Wei Ma

    2012-02-01

    Full Text Available The surface functionalization of inorganic nanostructures is an effective approach for enriching the potential applications of existing nanomaterials. Inorganic nanotubes attract great research interest due to their one-dimensional structure and reactive surfaces. In this review paper, recent developments in surface functionalization of an aluminosilicate nanotube, “imogolite”, are introduced. The functionalization processes are based on the robust affinity between phosphate groups of organic molecules and the aluminol (AlOH surface of imogolite nanotubes. An aqueous modification process employing a water soluble ammonium salt of alkyl phosphate led to chemisorption of molecules on imogolite at the nanotube level. Polymer-chain-grafted imogolite nanotubes were prepared through surface-initiated polymerization. In addition, the assembly of conjugated molecules, 2-(5’’-hexyl-2,2’:5’,2’’-terthiophen-5-ylethylphosphonic acid (HT3P and 2-(5’’-hexyl-2,2’:5’,2’’-terthiophen-5-ylethylphosphonic acid 1,1-dioxide (HT3OP, on the imogolite nanotube surface was achieved by introducing a phosphonic acid group to the corresponding molecules. The optical and photophysical properties of these conjugated-molecule-decorated imogolite nanotubes were characterized. Moreover, poly(3-hexylthiophene (P3HT chains were further hybridized with HT3P modified imogolite to form a nanofiber hybrid.

  9. Reactions of substituted aromatic molecules on the silicon(001) surface

    Science.gov (United States)

    Coutler, Sarah Kathryn

    Organic molecules possess unique physical and electronic properties that could be incorporated as components in new technologies, such as molecular electronics, biosensors and DNA chip arrays. While the properties of individual molecules often can be measured and predicted, the technological value of organic molecules for these types of applications requires the ability to understand and manipulate how physical and electronic properties are affected by bonding to a surface. Consequently, integration of organic systems with existing silicon-based technology necessitates a thorough investigation of the interfacial chemistry involved in adsorption processes. On a molecular scale, the delocalized electrons of a conjugated system could be used to carry charge from one point to another. Therefore, the interaction of pi-conjugated molecules with the technologically important Si(001) surface is of particular interest. X-ray Photoelectron Spectroscopy (XPS), Scanning Tunneling Microscopy (STM) and Fourier Transform Infrared (FTIR) Spectroscopy were used to investigate the bonding selectivity of several model aromatic molecules. Analysis of the infrared spectra of benzene, toluene and xylene suggest that these simple aromatic molecules covalently bond with the Si(001) surface, resulting in a loss of aromaticity. Studies of aromatic rings with other, more reactive substituent groups containing sulfur, oxygen, nitrogen, iodine or carbon atoms, indicate that the majority of these molecules preferentially adsorb to the surface through the substituent group. Careful consideration of the role played by both the electron-rich substituent groups and the silicon dimers in controlling selectivity leads to new insights regarding adsorption mechanisms. This knowledge, in turn, provides a method for selecting and designing molecules that will preferentially chemisorb on the Si(001) surface in a highly predictable manner. Preliminary studies correlating the chemical identity of the

  10. Design of New Antibacterial Active Molecules

    OpenAIRE

    Vavříková, Eva

    2010-01-01

    The main task of the thesis was a design and synthesis of new potential antimycobacterial active molecules. Presently, the appearance of MDR-TB strains is alarming and the development of new therapeutical agents is necessary. The work is divided into two parts; first one is related to aminopolysaccharide chitosan and its connection with appropriate antimycobacterial drugs or dyes, second part is concerned with modifications of current antituberculotics. Due to the structure and physico-chemic...

  11. Mechanics of active surfaces

    Science.gov (United States)

    Salbreux, Guillaume; Jülicher, Frank

    2017-09-01

    We derive a fully covariant theory of the mechanics of active surfaces. This theory provides a framework for the study of active biological or chemical processes at surfaces, such as the cell cortex, the mechanics of epithelial tissues, or reconstituted active systems on surfaces. We introduce forces and torques acting on a surface, and derive the associated force balance conditions. We show that surfaces with in-plane rotational symmetry can have broken up-down, chiral, or planar-chiral symmetry. We discuss the rate of entropy production in the surface and write linear constitutive relations that satisfy the Onsager relations. We show that the bending modulus, the spontaneous curvature, and the surface tension of a passive surface are renormalized by active terms. Finally, we identify active terms which are not found in a passive theory and discuss examples of shape instabilities that are related to active processes in the surface.

  12. DFT study of water adsorption on lignite molecule surface.

    Science.gov (United States)

    Gao, Zhengyang; Ding, Yi; Yang, Weijie; Han, Wentao

    2017-01-01

    High moisture content is a main characteristic of low-rank coal, such as lignite. Numerous oxygen containing functional groups in lignite make it represent some special properties, and these functional groups affect the adsorption mechanisms of water molecules on lignite surface. This study reports some typical water · · · lignite conformations, along with a detailed analysis of the geometry, electrostatic potential distribution, reduced density gradient of interaction, and interaction energy decomposition. The results show that water molecules tend to aggregate around functional groups, and hydrogen bonds play a dominant role in the interaction. The adsorption energy of water cluster on lignite surface is larger than that of isolated water molecule, a good linear relationship between the interaction distance and adsorption energy of layers has been found. Since water is a polar molecule, the local minima and maxima of electrostatic potential in conformations increase along with more water adsorbing on lignite surface. Reduced density gradient analysis shows that H-bonds, van der Waals interaction, and a little steric make up the interaction between water cluster and lignite molecule. In these studied conformations which mainly are H-bond complexes, electrostatic and exchange repulsion play a dominant role, whereas polarization and dispersion make relatively small contribution to the interaction. Attractive and repulsive interaction both affect the stability of water · · · lignite conformations.

  13. Surface-confined electroactive molecules for multistate charge storage information.

    Science.gov (United States)

    Mas-Torrent, M; Rovira, C; Veciana, J

    2013-01-18

    Bi-stable molecular systems with potential for applications in binary memory devices are raising great interest for device miniaturization. Particular appealing are those systems that operate with electrical inputs since they are compatible with existing electronic technologies. The processing of higher memory densities in these devices could be accomplished by increasing the number of memory states in each cell, although this strategy has not been much explored yet. Here we highlight the recent advances devoted to the fabrication of charge-storage molecular surface-confined devices exhibiting multiple states. Mainly, this goal has been realized immobilizing a variety (or a combination) of electroactive molecules on a surface, although alternative approaches employing non-electroactive systems have also been described. Undoubtedly, the use of molecules with chemically tunable properties and nanoscale dimensions are raising great hopes for the devices of the future in which molecules can bring new perspectives such as multistability.

  14. Fundamental properties of molecules on surfaces. Molecular switching and interaction of magnetic molecules with superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Hatter, Nino

    2016-12-14

    In this thesis, we investigate individual molecular switches and metal-organic complexes on surfaces with scanning tunneling microscopy (STM) and spectroscopy (STS) at low temperatures. One focus addresses the switching ability and mechanism of diarylethene on Ag(111). The other focus lies on resolving and tuning magnetic interactions of individual molecules with superconductors. 4,4'-(4,4'-(perfluorocyclopent-1-ene-1,2-diyl)bis (5-methylthiophene-4,2-diyl)dip yridine (PDTE) is a prototypical photochromic switch. We can induce a structural change of individual PDTE molecules on Ag(111) with the STM tip. This change is accompanied by a reduction of the energy gap between the occupied and unoccupied molecular orbitals. Density functional theory (DFT) calculations reveal that the induced switching corresponds to a ring-closing reaction from an open isomer in a flat adsorption configuration to a ring-closed isomer with its methyl groups in a cis configuration. The final product is thermodynamically stabilized by strong dispersion interactions with the surface. A linear dependence of the switching threshold with the tip-sample distance with a minimal threshold of 1.4 V is found, which we assign to a combination of an electric-field induced process and a tunneling-electron contribution. DFT calculations suggest a large activation barrier for a ring-closing reaction from the open flat configuration into the closed cis configuration. The interaction of magnetic molecules with superconductors is studied on manganese phthalocyanine (MnPc) adsorbed on Pb(111). We find triplets of Shiba states inside the superconducting gap. Different adsorption sites of MnPc provide a large variety of exchange coupling strengths, which lead to a collective energy shift of the Shiba triplets. We can assign the splitting of the Shiba states to be an effect of magnetic anisotropy in the system. A quantum phase transition from a ''Kondo screened'' to a &apos

  15. Internal state distributions of molecules scattering and desorbing from surfaces

    International Nuclear Information System (INIS)

    Auerbach, D.J.

    1983-01-01

    Attempts are made to interpret scattering experiments of NO molecules on Ag(111) where a (rotational) state-specific detector has been used. A model using an anisotropic potential is proposed to explain the observed incoming energy- and angle dependence. The so-called rotational rainbows are explained. It is concluded, that in this way information on intermolecular potentials and the transfer of translational to rotational energy in the dynamics of trapping and sticking of molecules on surfaces can be extracted. (G.Q.)

  16. Low-energy electron scattering from molecules, biomolecules and surfaces

    CERN Document Server

    Carsky, Petr

    2011-01-01

    Since the turn of the 21st century, the field of electron molecule collisions has undergone a renaissance. The importance of such collisions in applications from radiation chemistry to astrochemistry has flowered, and their role in industrial processes such as plasma technology and lighting are vital to the advancement of next generation devices. Furthermore, the development of the scanning tunneling microscope highlights the role of such collisions in the condensed phase, in surface processing, and in the development of nanotechnology.Low-Energy Electron Scattering from Molecules, Biomolecule

  17. Interactions between nitrogen molecules and barium atoms on Ru (0001) surface

    International Nuclear Information System (INIS)

    Zhao Xinxin; Mi Yiming; Xu Hongxia; Wang Lili; Ren Li; Tao Xiangming; Tan Mingqiu

    2011-01-01

    We had performed first principles calculations on interactions between nitrogen molecules and barium atoms on Ru (0001) surface using density function theory methods. It was shown that effects of barium atoms weakened the bond strength of nitrogen molecules. The bond length of nitrogen molecule increases from 0.113 nm on Ru (001)-N 2 to 0.120 nm on Ru (001)-N 2 /Ba surface. While stretch vibrational frequency of nitrogen molecule decreased from 2222 cm -1 and charge transfer toward nitrogen molecule increased from 0.3 e to 1.1 e. Charge was mainly translated from 6 s orbitals of barium atoms to 4 d orbitals of substrate, which enhanced the hybridization between 4 d and 2 π orbitals and increased the dipole moment of 5 σ and d π orbitals of nitrogen molecule. The molecular dipole moment of nitrogen molecule was increased by -0.136 e Anstrom. It was suggested that barium had some characters to be an electronic promoter on the process of activating nitrogen molecules on Ru (0001) surface. (authors)

  18. Preparation and single molecule structure of electroactive polysilane end-grafted on a crystalline silicon surface

    Science.gov (United States)

    Furukawa, Kazuaki; Ebata, Keisuke

    2000-12-01

    Electrically active polysilanes of poly(methylphenylsilane) (PMPS) and poly[bis(p-n-butylphenyl)silane] (PBPS), which are, respectively, known as a good hole transporting material and a near-ultraviolet electroluminescent material, are end-grafted directly on a crystalline silicon surface. The single polysilane molecules are clearly distinguished one from the other on the surface by means of atomic force microscopy observations. End-grafted single molecules of PMPS are observed as dots while end-grafted PBPS appear as worms extending for more than 100 nm on the crystalline silicon surface.

  19. DNA origami as biocompatible surface to match single-molecule and ensemble experiments

    Science.gov (United States)

    Gietl, Andreas; Holzmeister, Phil; Grohmann, Dina; Tinnefeld, Philip

    2012-01-01

    Single-molecule experiments on immobilized molecules allow unique insights into the dynamics of molecular machines and enzymes as well as their interactions. The immobilization, however, can invoke perturbation to the activity of biomolecules causing incongruities between single molecule and ensemble measurements. Here we introduce the recently developed DNA origami as a platform to transfer ensemble assays to the immobilized single molecule level without changing the nano-environment of the biomolecules. The idea is a stepwise transfer of common functional assays first to the surface of a DNA origami, which can be checked at the ensemble level, and then to the microscope glass slide for single-molecule inquiry using the DNA origami as a transfer platform. We studied the structural flexibility of a DNA Holliday junction and the TATA-binding protein (TBP)-induced bending of DNA both on freely diffusing molecules and attached to the origami structure by fluorescence resonance energy transfer. This resulted in highly congruent data sets demonstrating that the DNA origami does not influence the functionality of the biomolecule. Single-molecule data collected from surface-immobilized biomolecule-loaded DNA origami are in very good agreement with data from solution measurements supporting the fact that the DNA origami can be used as biocompatible surface in many fluorescence-based measurements. PMID:22523083

  20. Novel approaches for single molecule activation and detection

    CERN Document Server

    Benfenati, Fabio; Torre, Vincent

    2014-01-01

    How can we obtain tools able to process and exchange information at the molecular scale In order to do this, it is necessary to activate and detect single molecules under controlled conditions. This book focuses on the generation of biologically-inspired molecular devices. These devices are based on the developments of new photonic tools able to activate and stimulate single molecule machines. Additionally, new light sensitive molecules can be selectively activated by photonic tools. These technological innovations will provide a way to control activation of single light-sensitive molecules, a

  1. Preservation of organic molecules at Mars' near-surface

    Science.gov (United States)

    Freissinet, Caroline

    2016-07-01

    One of the biggest concerns for the in situ detection of organics on extraterrestrial environment is the preservation potential of the molecules at the surface and subsurface given the harsh radiation conditions and oxidants they are exposed to. The Mars Science Laboratory (MSL) search for hydrocarbons is designed to understand taphonomic windows of organic preservation in the Mars' near-surface. The Sample Analysis at Mars (SAM) instrument on the MSL Curiosity rover discovered chlorohydrocarbon indigenous to a mudstone drilled sample, Cumberland (CB). The discovery of chlorohydrocarbons in the martian surface means that reduced material with covalent bonds has survived despite the severe degrading conditions. However, the precursors of the chlorohydrocarbons detected by pyrolysis at CB remain unknown. Organic compounds in this ancient sedimentary rock on Mars could include polycyclic aromatic hydrocarbons and refractory organic material, either formed on Mars from igneous, hydrothermal, atmospheric, or biological processes or, alternatively, delivered directly to Mars via meteorites, comets, or interplanetary dust particles. It has been postulated that organic compounds in near-surface rocks may undergo successive oxidation reactions that eventually form metastable benzenecarboxylates, including phthalic and mellitic acids. These benzenecarboxylates are good candidates as the precursors of the chlorohydrocarbons detected in SAM pyrolysis at CB. Indeed, recently, SAM performed a derivatization experiments on a CB sample, using the residual vapor of N-methyl-N-tertbutylsilyltrifluoroacetamide (MTBSTFA) leaking into the system. The preliminary interpretations are compatible with the presence of benzocarboxylates, coincidently with long chain carboxylic acids and alcohols. The analysis of this interesting data set to identify these derivatization products, as well as future SAM measurements on Mt Sharp, should shed additional light on the chemical nature and the

  2. Amphoteric surface active agents

    OpenAIRE

    Eissa, A.M. F.

    1995-01-01

    2-[trimethyl ammonium, triethyl ammonium, pyridinium and 2-amino pyridinium] alkanoates, four series of surface active agents containing carbon chain C12, C14, C16 and C18carbon atoms, were prepared. Their structures were characterized by microanalysis, infrared (IR) and nuclear magnetic resonance (NMR). Surface and interfacial tension, Krafft point, wetting time, emulsification power, foaming height a...

  3. Structure determination by photoelectron diffraction of small molecules on surfaces

    International Nuclear Information System (INIS)

    Booth, N.A.

    1998-05-01

    The synchrotron radiation based technique of Photoelectron Diffraction (PhD) has been applied to three adsorption systems. Structure determinations, are presented for each system which involve the adsorption of small molecules on the low index {110} plane of single crystal Cu and Ni substrates. For the NH 3 -Cu(110) system PhD was successful in determining a N-Cu bondlength of 2.05 ± 0.03 A as well as values for the anisotropic vibrational amplitudes of the N and an expansion of the 1st to 2nd Cu substrate layer spacing from the bulk value of 0.08 ± 0.08 A. The most significant and surprising structural parameter determined for this system was that the N atom occupies an asymmetric adsorption site. Rather than being situated in the expected high symmetry atop site the N atom was found to be offset parallel to the surface by 0.37 ± 0.12 A in the [001] azimuth. In studying the glycine-Cu(110) system the adsorption structure of an amino-acid has been quantified. The local adsorption geometries of all the atoms involved in the molecule to surface bond have been determined. The glycine molecule is found to be bonded to the surface via both its amino and carboxylate functional groups. The molecule straddles two [11-bar0] rows of the Cu substrate. The two O atoms are found to be in identical sites both approximately atop Cu atoms on the [11-bar0] rows offset parallel to the surface by 0.80 ± 0.05 A in the [001] azimuth, the O-Cu bondlength was found to be 2.03 ± 0.05 A. The N atom was also found to adsorb in an approximately atop geometry but offset parallel to the surface by 0.24 ± 0.10A in the [11-bar0] direction, the N-Cu bondlength was found to be 2.05± 0.05 A. PhD was unsuccessful in determining the positions of the two C atoms that form a bridge between the two functional groups bonded to the surface due to difficulties in separating the two inequivalent contributions to the final intensity modulation function. For the CN-Ni(110) system both PhD and Near Edge

  4. Surface chemical reactions induced by molecules electronically-excited in the gas

    DEFF Research Database (Denmark)

    Petrunin, Victor V.

    2011-01-01

    and alignment are taking place, guiding all the molecules towards the intersections with the ground state PES, where transitions to the ground state PES will occur with minimum energy dissipation. The accumulated kinetic energy may be used to overcome the chemical reaction barrier. While recombination chemical...... beams inducing the reaction can be used to distinguish the new process we try to investigate from chemical reactions induced by photoexcitation within adsorbed molecules and/or gas phase photolysis.......We present a model suggesting high chemical activity of electronically-excited molecules colliding with an isolator surface. Initial photochemical event is accounted for as the result of molecular evolution on the electronically-excited potential energy surface (PES), where acceleration...

  5. Template Synthesis of Tubular Nanostructures for Loading Biologically Active Molecules.

    Science.gov (United States)

    Karatas, Aysegul; Algan, Aslıhan Hilal

    2017-01-01

    The template synthesis is a low cost, simple and versatile nanofabrication method to produce cylindrical/tubular nanostructures with controllable dimensions such as length, diameter and aspect ratio. This method utilizes nanoporous membranes such as anodized aluminum oxide (AAO) or polycarbonate (PC) as templates which have nanosized specific, cylindrical and uniform inner pores to be coated with the desired material. Template synthesized nanotubular structures have been produced from variety of materials including ceramics, polymers and proteins for loading biologically active molecules. Available procedures of material deposition into the template nanopores consist of several techniques like wetting (melt or solution wetting), layer-by-layer (LbL) assembly and sol-gel chemistry. Template synthesis enables not only control of the geometry of the resulting nanostructures but also provides nanovehicles having separated inner and outer surfaces which can be variously functionalized. Tubular nanostructures fabricated by this method have numerous potential applications including delivery of biologically active molecules such as drugs, gene, enzymes and proteins. In this review we aimed to present up-to-date works on the template based synthesis which has greatly facilitated the fabrication of polymer and protein tubular nanostructures, principally. The strategies regarding the synthesis and designing of these promising tubular nanostructures together with recent approaches relevant of drug delivery was also presented. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  6. Coupling of therapeutic molecules onto surface modified coralline hydroxyapatite.

    Science.gov (United States)

    Murugan, R; Ramakrishna, S

    2004-07-01

    Surface modification and coupling of therapeutic molecules, tetracycline, onto coralline hydroxyapatite (CHA) and their in vitro evaluations were described in this study. Initially, CHA was graft polymerized with glycidylmethacrylate (GMA) using redox initiators and subsequently coupled to tetracycline through epoxy groups. The CHA grafted with polyGMA (CHA-g-PGMA) was characterized by Fourier transform infrared spectroscopy and powder X-ray diffraction (XRD) for proof of grafting. The absorption peaks pertaining to epoxy and ester carbonyl groups were observed for the graft polymer due to PGMA grafting. The XRD results signified that there was no secondary phase in the apatite lattice and crystallinity was also not affected by grafting, which suggested that the PGMA chains were grafted only on the surface of CHA. Drug loading and releasing was evaluated and found that CHA-g-PGMA exhibited higher loading efficiency than CHA. The in vitro release of tetracycline was performed in phosphate buffered saline under physiological condition and the release profiles showed that the tetracycline-containing graft polymer releases the drug for prolonged period as compared to CHA. Based on the experimental results, CHA-g-PGMA appears to be a promising biomaterial for drug delivery.

  7. Amphoteric surface active agents

    Directory of Open Access Journals (Sweden)

    Eissa, A.M. F.

    1995-10-01

    Full Text Available 2-[trimethyl ammonium, triethyl ammonium, pyridinium and 2-amino pyridinium] alkanoates, four series of surface active agents containing carbon chain C12, C14, C16 and C18carbon atoms, were prepared. Their structures were characterized by microanalysis, infrared (IR and nuclear magnetic resonance (NMR. Surface and interfacial tension, Krafft point, wetting time, emulsification power, foaming height and critical micelle concentration (cmc were determined and a comparative study was made between their chemical structure and surface active properties. Antimicrobial activity of these surfactants was also determined.

    Se prepararon cuatro series de agentes tensioactivos del tipo 2-[trimetil amonio, trietil amonio, piridinio y 2-amino piridinio] alcanoatos, que contienen cadenas carbonadas con C12, C14, C16 y C18 átomos de carbono.
    Se determinaron la tensión superficial e interfacial, el punto de Krafft, el tiempo humectante, el poder de emulsionamiento, la altura espumante y la concentración critica de miscela (cmc y se hizo un estudio comparativo entre la estructura química y sus propiedades tensioactivas. Se determinó también la actividad antimicrobiana de estos tensioactivos. Estas estructuras se caracterizaron por microanálisis, infrarrojo (IR y resonancia magnética nuclear (RMN.

  8. Molecules with multiple switching units on a Au(111) surface: self-organization and single-molecule manipulation

    Science.gov (United States)

    Mielke, Johannes; Selvanathan, Sofia; Peters, Maike; Schwarz, Jutta; Hecht, Stefan; Grill, Leonhard

    2012-10-01

    Three different molecules, each containing two azobenzene switching units, were synthesized, successfully deposited onto a Au(111) surface by sublimation and studied by scanning tunneling microscopy at low temperatures. To investigate the influence of electronic coupling between the switching units as well as to the surface, the two azo moieties were connected either via π-conjugated para-phenylene or decoupling meta-phenylene bridges, and the number of tert-butyl groups was varied in the meta-phenylene-linked derivatives. Single molecules were found to be intact after deposition as identified by their characteristic appearance in STM images. Due to their mobility on the Au(111) surface at room temperature, the molecules spontaneously formed self-organized molecular arrangements that reflected their chemical structure. While lateral displacement of the molecules was accomplished by manipulation, trans-cis isomerization processes, typical for azobenzene switches, could not be induced.

  9. Investigating the conformation of polymeric dispersant molecules on nanoparticle surface

    International Nuclear Information System (INIS)

    Yasin, S.; Luckham, P.F.; Iqbal, T

    2016-01-01

    Block copolymers are widely used as stabilizers in industrial dispersions. These polymers adsorb on surfaces by an anchor chain and extend by a hydrophilic chain. Scaling model or de Gennes theory has been used to determine the grafting density of the block copolymers. By implementing this theory to the block copolymers, conformation of the polymer molecules as a function of distance between adjacent anchor chains can be determined. The scaling model was applied to a selection of block copolymers (PE/F 103, PE/F 108, NPE1800, Triton X100, Triton X405, Lugalvan BNO12, Hypermer LP1, Hypermer B246 and OLOA 11000) in this study. The cross sectional area sc, distance s (square root of sc) and the Flory radius (end to end dimension of polymer), Rf, for all the polymers was determined. The cross sectional area per PEO (Poly Ethylene Oxide) chain (nm2) was found to be increasing with the size of stabilizing chain. Triton X100 and Lugalvan BNO12 has the smaller stabilizing chains so occupy smaller cross sectional areas whereas PE/F108 and triton X405 have larger number of PEO units and occupy a larger cross sectional area. This shows that stabilizing chain regulates the adsorption amounts that are lower in case of lower number of EO units. The application of de Gennes theory to experimental results suggested brush configuration of adsorbed polymer molecules in case of PE/F 103, PE/F 108, Triton X100, Triton X405, NPE1800, Lugalvan BNO12, Hypermer B246 and OLOA 11000. Whereas, Hypermer LP1 is more likely found to be adsorbed on graphitic carbon black in loops and trains. (author)

  10. Single-molecule conductivity of non-redox and redox molecules at pure and gold-mined Au(111)-electrode surfaces

    DEFF Research Database (Denmark)

    Zhang, Jingdong; Chi, Qijin; Ulstrup, Jens

    media supported by comprehensive theoretical frames, have emerged as core approaches in these exciting areas. Single-molecule redox electrochemistry is rooted in two major areas. One is the preparation of well-defined (atomically planar) electrode surfaces modified by molecular monolayers (SAMs). High...... to surface-mined Au-atoms. In addition the SAMs ensure protein/enzyme immobilization gentle enough that the proteins retain electron transfer or enzyme activity in a variety of local environments. The second area is the mapping and control of the immobilized redox molecules and metalloproteins themselves...

  11. Differential Expression of Osteo-Modulatory Molecules in Periodontal Ligament Stem Cells in Response to Modified Titanium Surfaces

    Directory of Open Access Journals (Sweden)

    So Yeon Kim

    2014-01-01

    Full Text Available This study assessed differential gene expression of signaling molecules involved in osteogenic differentiation of periodontal ligament stem cells (PDLSCs subjected to different titanium (Ti surface types. PDLSCs were cultured on tissue culture polystyrene (TCPS, and four types of Ti discs (PT, SLA, hydrophilic PT (pmodPT, and hydrophilic SLA (modSLA with no osteoinductive factor and then osteogenic activity, including alkaline phosphatase (ALP activity, mRNA expression of runt-related gene 2, osterix, FOSB, FRA1, and protein levels of osteopontin and collagen type IA, were examined. The highest osteogenic activity appeared in PDLSCs cultured on SLA, compared with the TCPS and other Ti surfaces. The role of surface properties in affecting signaling molecules to modulate PDLSC behavior was determined by examining the regulation of Wnt pathways. mRNA expression of the canonical Wnt signaling molecules, Wnt3a and β-catenin, was higher on SLA and modSLA than on smooth surfaces, but gene expression of the calcium-dependent Wnt signaling molecules Wnt5a, calmodulin, and NFATc1 was increased significantly on PT and pmodPT. Moreover, integrin α2/β1, sonic hedgehog, and Notch signaling molecules were affected differently by each surface modification. In conclusion, surface roughness and hydrophilicity can affect differential Wnt pathways and signaling molecules, targeting the osteogenic differentiation of PDLSCs.

  12. Friction mediated by redox-active supramolecular connector molecules.

    Science.gov (United States)

    Bozna, B L; Blass, J; Albrecht, M; Hausen, F; Wenz, G; Bennewitz, R

    2015-10-06

    We report on a friction study at the nanometer scale using atomic force microscopy under electrochemical control. Friction arises from the interaction between two surfaces functionalized with cyclodextrin molecules. The interaction is mediated by connector molecules with (ferrocenylmethyl)ammonium end groups forming supramolecular complexes with the cyclodextrin molecules. With ferrocene connector molecules in solution, the friction increases by a factor of up to 12 compared to control experiments without connector molecules. The electrochemical oxidation of ferrocene to ferrocenium causes a decrease in friction owing to the lower stability of ferrocenium-cyclodextrin complex. Upon switching between oxidative and reduction potentials, a change in friction by a factor of 1.2-1.8 is observed. Isothermal titration calorimetry reveals fast dissociation and rebinding kinetics and thus an equilibrium regime for the friction experiments.

  13. Formation of self-assembled monolayer of curcuminoid molecules on gold surfaces

    International Nuclear Information System (INIS)

    Berlanga, Isadora; Etcheverry-Berríos, Álvaro; Mella, Andy; Jullian, Domingo; Gómez, Victoria Alejandra; Aliaga-Alcalde, Núria; Fuenzalida, Victor; Flores, Marcos

    2017-01-01

    Highlights: • Thiophene curcuminoid molecules deposited on a gold surface by immersion. • Molecular dynamic studies of the molecular arrangement approaching the surface. • XPS and STM studies showing different arrangement of the molecules on the surface. • Molecular Interaction with surface depends on the sulfur position in thiophene rings. • Temporal evolution of the molecular arrangement on the surface. - Abstract: We investigated the formation of self-assembled monolayers of two thiophene curcuminoid molecules, 2-thphCCM (1) and 3-thphCCM (2), on polycrystalline gold substrates prepared by immersion of the surfaces in a solution of the molecules during 24 h. The functionalized surfaces were studied by scanning tunneling microscopy (STM) and X-ray photoelectron spectroscopy (XPS). Despite the fact that both molecules have the same composition and almost the same structure, these molecules exhibit different behavior on the gold surface, which can be explained by the different positions of the sulfur atoms in the terminal aromatic rings. In the case of molecule 1, the complete formation of a SAM can be observed after 24 h of immersion. In the case of molecule 2, the transition from flat-lying to upright configuration on the surface is still in process after 24 h of immersion. This is attributed to the fact that molecule 2 have the sulfur atoms more exposed than molecule 1.

  14. Formation of self-assembled monolayer of curcuminoid molecules on gold surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Berlanga, Isadora [Departamento de Física, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Av. Blanco Encalada 2008, Santiago (Chile); Etcheverry-Berríos, Álvaro; Mella, Andy; Jullian, Domingo [Departamento de Ciencia de los Materiales, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Beaucheff 851, Santiago (Chile); Gómez, Victoria Alejandra [Departamento de Física, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Av. Blanco Encalada 2008, Santiago (Chile); Aliaga-Alcalde, Núria [ICREA (Institució Catalana de Recerca i Estudis Avançats), Passeig Lluís Companys, 23, 08018, Barcelona (Spain); CSIC-ICMAB (Institut de Ciència dels Materials de Barcelona), Campus de la Universitat Autònoma de Barcelona, 08193 Bellaterra (Spain); Fuenzalida, Victor [Departamento de Física, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Av. Blanco Encalada 2008, Santiago (Chile); Flores, Marcos, E-mail: mflorescarra@ing.uchile.cl [Departamento de Física, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Av. Blanco Encalada 2008, Santiago (Chile); and others

    2017-01-15

    Highlights: • Thiophene curcuminoid molecules deposited on a gold surface by immersion. • Molecular dynamic studies of the molecular arrangement approaching the surface. • XPS and STM studies showing different arrangement of the molecules on the surface. • Molecular Interaction with surface depends on the sulfur position in thiophene rings. • Temporal evolution of the molecular arrangement on the surface. - Abstract: We investigated the formation of self-assembled monolayers of two thiophene curcuminoid molecules, 2-thphCCM (1) and 3-thphCCM (2), on polycrystalline gold substrates prepared by immersion of the surfaces in a solution of the molecules during 24 h. The functionalized surfaces were studied by scanning tunneling microscopy (STM) and X-ray photoelectron spectroscopy (XPS). Despite the fact that both molecules have the same composition and almost the same structure, these molecules exhibit different behavior on the gold surface, which can be explained by the different positions of the sulfur atoms in the terminal aromatic rings. In the case of molecule 1, the complete formation of a SAM can be observed after 24 h of immersion. In the case of molecule 2, the transition from flat-lying to upright configuration on the surface is still in process after 24 h of immersion. This is attributed to the fact that molecule 2 have the sulfur atoms more exposed than molecule 1.

  15. Spontaneous dissociation of a conjugated molecule on the Si(100) surface

    DEFF Research Database (Denmark)

    Lin, Rong; Galili, Michael; Quaade, Ulrich

    2002-01-01

    The adsorption mechanism of alpha-sexithiophene (alpha-6T) on the clean Si(100)-(2x1) surface has been investigated using scanning tunneling microscopy (STM) and first principles electronic structure calculations. We find that at submonolayer coverage, the alpha-6T molecules are not stable...... coverage, the STM images show the existence of complete alpha-6T molecules. In addition, results of the adsorption behavior of alpha-6T molecules on the H-passivated Si(100)-(2x1) surface are reported. On this surface the molecules are highly mobile at room temperature due to the weak molecule...

  16. Small-molecule allosteric activators of sirtuins.

    Science.gov (United States)

    Sinclair, David A; Guarente, Leonard

    2014-01-01

    The mammalian sirtuins (SIRT1-7) are NAD(+)-dependent lysine deacylases that play central roles in cell survival, inflammation, energy metabolism, and aging. Members of this family of enzymes are considered promising pharmaceutical targets for the treatment of age-related diseases including cancer, type 2 diabetes, inflammatory disorders, and Alzheimer's disease. SIRT1-activating compounds (STACs), which have been identified from a variety of chemical classes, provide health benefits in animal disease models. Recent data point to a common mechanism of allosteric activation by natural and synthetic STACs that involves the binding of STACs to a conserved N-terminal domain in SIRT1. Compared with polyphenols such as resveratrol, the synthetic STACs show greater potency, solubility, and target selectivity. Although considerable progress has been made regarding SIRT1 allosteric activation, key questions remain, including how the molecular contacts facilitate SIRT1 activation, whether other sirtuin family members will be amenable to activation, and whether STACs will ultimately prove safe and efficacious in humans.

  17. Theory of coherent molecule to surface electron injection: An ...

    Indian Academy of Sciences (India)

    Administrator

    erogeneous electron transfer from a molecule to a semiconductor occurs before full vibrational relaxa- tion of the excited molecule is achieved. 5,6. Accor- dingly, theoretical description of the decay of the initial state has been formulated to include vibra- tional coherence in the transfer process. 4. 2. Analytical model.

  18. Effective medium potentials for molecule-surface interactions: H2 on Cu and Ni surfaces

    DEFF Research Database (Denmark)

    Nørskov, Jens Kehlet

    1989-01-01

    outside metal surfaces and the applicability is illustrated for H2 adsorbing on various Cu and Ni surfaces. Although very approximate, the calculated potentials seem to include a number of features observed experimentally: Ni is more active in dissociating H2 than Cu, and open surfaces are more active...... than close-packed ones. Moreover, the method is simple enough that one can contemplate studying variations in dissociation pathways over the surface unit cell. For the Cu surfaces these variations are substantial accounting for at least part of the variation of the sticking coefficient with the kinetic...

  19. Selectivity by Small-Molecule Inhibitors of Protein Interactions Can Be Driven by Protein Surface Fluctuations

    Science.gov (United States)

    Johnson, David K.; Karanicolas, John

    2015-01-01

    Small-molecules that inhibit interactions between specific pairs of proteins have long represented a promising avenue for therapeutic intervention in a variety of settings. Structural studies have shown that in many cases, the inhibitor-bound protein adopts a conformation that is distinct from its unbound and its protein-bound conformations. This plasticity of the protein surface presents a major challenge in predicting which members of a protein family will be inhibited by a given ligand. Here, we use biased simulations of Bcl-2-family proteins to generate ensembles of low-energy conformations that contain surface pockets suitable for small molecule binding. We find that the resulting conformational ensembles include surface pockets that mimic those observed in inhibitor-bound crystal structures. Next, we find that the ensembles generated using different members of this protein family are overlapping but distinct, and that the activity of a given compound against a particular family member (ligand selectivity) can be predicted from whether the corresponding ensemble samples a complementary surface pocket. Finally, we find that each ensemble includes certain surface pockets that are not shared by any other family member: while no inhibitors have yet been identified to take advantage of these pockets, we expect that chemical scaffolds complementing these “distinct” pockets will prove highly selective for their targets. The opportunity to achieve target selectivity within a protein family by exploiting differences in surface fluctuations represents a new paradigm that may facilitate design of family-selective small-molecule inhibitors of protein-protein interactions. PMID:25706586

  20. Theoretical studies of inelastic molecule-surface and resonant electron-atom and electron-molecule scattering

    International Nuclear Information System (INIS)

    Mowrey, R.C. Jr.

    1985-01-01

    In part I, two problems in the inelastic scattering of molecules from nonvibrating surfaces are discussed. First, the close coupling (CC) method is used to study the orientational dependence of the transition probabilities for vibrationally and rotationally inelastic scattering of H 2 and N 2 from flat surfaces. The dependence of vibrational transition probabilities on the orientation of the molecule is strong but decreases as the energy increases. Second, a new approximation to the CC method for treating scattering of molecules from corrugated surfaces is discussed. The proposed local normal model of j/sub z/ conservation assumes that the component of the rotational angular momentum of the incident molecule which is parallel to the normal to the surface at the impact point is conserved during a collision. In part II, the use of the complex basis function method to study two shape resonances in electron scattering is discussed. The complex self-consistent-field (CSCF) method was used to obtain the position and width of the 2 D shape resonance in electron-calcium scattering. Comparison with experimental results shows that the lifetime is influenced by correlation effects. The CSCF and complex configuration interaction (CCI) methods were used to obtain the complex potential energy function for nuclear motion for the 2 Σ/sub u/ + resonance state of H 2 -

  1. Organic Molecules On the Surfaces of Iapetus and Phoebe

    Science.gov (United States)

    Pendleton, Yvonne J.; Dalle Ore, Cristina M.; Clark, Roger N.; Cruikshank, Dale P.

    2017-01-01

    Absorption bands of both aliphatic and aromatic organic molecules are found in the reflectance spectra of Saturn satellites Iapetus, Phoebe, and Hyperion obtained with the Cassini Visible-Infrared Mapping Spectrometer (VIMS). The VIMS data do not fully resolve the individual bands of C-H functional groups specific to particular molecules, but instead show absorption envelopes representing blended clusters of the bands of aromatic (approximately 3.28 microns) and aliphatic (approximately 3.4 microns) hydrocarbons known in spectra of interstellar dust. In Cruikshank et al. (2014), we matched components of the unresolved hydrocarbon band envelopes with clusters of bands of a range of functional groups in specific types of organic compounds (e.g., normal and N-substituted polycyclic aromatic hydrocarbons, olefins, cycloalkanes, and molecules with lone-pair interactions of N and O with CH3+). In the work reported here, we revisit the spectra of Iapetus and Phoebe using VIMS data processed with improved radiometric and wavelength calibration (denoted RC19). The band envelopes of both aromatic and aliphatic hydrocarbons are now more clearly defined, corroborating the provisional assignment of specific classes of molecules in Cruikshank et al. 2014, but permitting a more reliable quantitative assessment of the relative contributions of those classes, and a revision to the earlier estimate of the ratio of the abundances of aromatic to aliphatic molecules.

  2. Electrically driven directional motion of a four-wheeled molecule on a metal surface

    NARCIS (Netherlands)

    Kudernac, Tibor; Ruangsupapichat, Nopporn; Parschau, Manfred; Macia, Beatriz; Katsonis, Nathalie; Harutyunyan, Syuzanna R.; Ernst, Karl-Heinz; Feringa, Ben L.

    2011-01-01

    Propelling single molecules in a controlled manner along an unmodified surface remains extremely challenging because it requires molecules that can use light, chemical or electrical energy to modulate their interaction with the surface in a way that generates motion. Nature's motor proteins(1,2)

  3. Strategies For Immobilization Of Bioactive Organic Molecules On Titanium Implant Surfaces – A Review

    Directory of Open Access Journals (Sweden)

    Panayotov Ivan V.

    2015-03-01

    Full Text Available Numerous approaches have been used to improve the tissue-implant interface of titanium (Ti and titanium alloy (Ti6Al4V. They all aim at increasing cell migration and attachment to the metal, preventing unspecific protein adsorption and improving post-implantation healing process. Promising methods for titanium and titanium alloy surface modification are based on the immobilization of biologically active organic molecules. New and interesting biochemical approaches to such surface modification include layer-by-layer deposition of polyelectrolyte films, phage display-selected surface binding peptides and self-assembled DNA monolayer systems. The present review summarizes the scientific information about these methods, which are at in vitro or in vivo development stages, and hopes to promote their future application in dental implantology and in oral and maxillofacial surgery.

  4. Surface formation routes of interstellar molecules : a laboratory study

    NARCIS (Netherlands)

    Sergio, Ioppolo

    2010-01-01

    It has been a long standing problem in astrochemistry to explain how molecules can form in a highly dilute environment as the interstellar medium. In recent years it has become clear that solid state reactions on icy grains play an important role in the formation of both simple and rather complex

  5. Incident energy dependence of scattering behavior of water molecules on Si (100) and graphite surfaces

    Science.gov (United States)

    Kihara, G.; Kotsubo, Y.; Yoshimoto, Y.; Kinefuchi, I.; Takagi, S.

    2016-11-01

    The interaction between water molecules and solid surfaces has a great impact on water vapor flows in nanostructures. We conduct molecular beam scattering experiments covering the incident energy range corresponding to the thermal energy at room temperature to investigate the scattering behavior of water molecules on silicon and graphite surfaces. The incident energy dependence of the scattering distributions exhibits opposite trends on these surfaces. Molecular dynamics simulations reveal that the difference is caused by the inertia effect of the incident molecules and the surface corrugations.

  6. Adsorption Mechanism of Inhibitor and Guest Molecules on the Surface of Gas Hydrates.

    Science.gov (United States)

    Yagasaki, Takuma; Matsumoto, Masakazu; Tanaka, Hideki

    2015-09-23

    The adsorption of guest and kinetic inhibitor molecules on the surface of methane hydrate is investigated by using molecular dynamics simulations. We calculate the free energy profile for transferring a solute molecule from bulk water to the hydrate surface for various molecules. Spherical solutes with a diameter of ∼0.5 nm are significantly stabilized at the hydrate surface, whereas smaller and larger solutes exhibit lower adsorption affinity than the solutes of intermediate size. The range of the attractive force is subnanoscale, implying that this force has no effect on the macroscopic mass transfer of guest molecules in crystal growth processes of gas hydrates. We also examine the adsorption mechanism of a kinetic hydrate inhibitor. It is found that a monomer of the kinetic hydrate inhibitor is strongly adsorbed on the hydrate surface. However, the hydrogen bonding between the amide group of the inhibitor and water molecules on the hydrate surface, which was believed to be the driving force for the adsorption, makes no contribution to the adsorption affinity. The preferential adsorption of both the kinetic inhibitor and the spherical molecules to the surface is mainly due to the entropic stabilization arising from the presence of cavities at the hydrate surface. The dependence of surface affinity on the size of adsorbed molecules is also explained by this mechanism.

  7. Molecules on vicinal Au surfaces studied by scanning tunnelling microscopy

    International Nuclear Information System (INIS)

    Kroeger, J; Neel, N; Jensen, H; Berndt, R; Rurali, R; Lorente, N

    2006-01-01

    Using low-temperature scanning tunnelling microscopy and spectroscopy we investigated the adsorption characteristics of 3,4,9,10-perylenetetracarboxylic-dianhydride and fullerenes on Au(788), Au(433), and Au(778). On Au(788) and Au(778), 3,4,9,10-perylenetetracarboxylic-dianhydride exhibits three coexisting superstructures, which do not reflect the periodicity of the hosting substrate. The adsorption on Au(433) leads to the formation of molecule chains along the step edges after annealing the sample. Fullerene molecules on Au(788) arrange in a mesh of islands, which extends over several hundreds of nanometres with an extraordinarily high periodicity. A combination of fullerene adsorption and annealing leads to facetting of Au(433) and the formation of extraordinarily long fullerene stripes

  8. Role of Adhesion Molecules in Eosinophil Activation: A Comparative Study on the Effect of Adhesion Molecules on Eosinophil Survival

    Directory of Open Access Journals (Sweden)

    Kazutoshi Yamaguchi

    2004-01-01

    Conclusions: The regulation of adhesion molecules, by not only preventing eosinophil adhesion but also eosinophil activation, may be a potential target in the treatment of allergic inflammatory disorders.

  9. Predicting receptor functionality of signaling lymphocyte activation molecule for measles virus hemagglutinin by docking simulation.

    Science.gov (United States)

    Suzuki, Yoshiyuki

    2017-05-01

    Predicting susceptibility of various species to a virus assists assessment of risk of interspecies transmission. Evaluation of receptor functionality may be useful in screening for susceptibility. In this study, docking simulation was conducted for measles virus hemagglutinin (MV-H) and immunoglobulin-like variable domain of signaling lymphocyte activation molecule (SLAM-V). It was observed that the docking scores for MV-H and SLAM-V correlated with the activity of SLAM as an MV receptor. These results suggest that the receptor functionality may be predicted from the docking scores of virion surface proteins and cellular receptor molecules. © 2017 The Societies and John Wiley & Sons Australia, Ltd.

  10. Single OR molecule and OR atomic circuit logic gates interconnected on a Si(100)H surface

    International Nuclear Information System (INIS)

    Ample, F; Joachim, C; Duchemin, I; Hliwa, M

    2011-01-01

    Electron transport calculations were carried out for three terminal OR logic gates constructed either with a single molecule or with a surface dangling bond circuit interconnected on a Si(100)H surface. The corresponding multi-electrode multi-channel scattering matrix (where the central three terminal junction OR gate is the scattering center) was calculated, taking into account the electronic structure of the supporting Si(100)H surface, the metallic interconnection nano-pads, the surface atomic wires and the molecule. Well interconnected, an optimized OR molecule can only run at a maximum of 10 nA output current intensity for a 0.5 V bias voltage. For the same voltage and with no molecule in the circuit, the output current of an OR surface atomic scale circuit can reach 4 μA.

  11. Confined Catalysis in the g-C3N4/Pt(111) Interface: Feasible Molecule Intercalation, Tunable Molecule-Metal Interaction, and Enhanced Reaction Activity of CO Oxidation.

    Science.gov (United States)

    Wang, Shujiao; Feng, Yingxin; Yu, Ming'an; Wan, Qiang; Lin, Sen

    2017-09-27

    The deposition of a two-dimensional (2D) atomic nanosheet on a metal surface has been considered as a new route for tuning the molecule-metal interaction and surface reactivity in terms of the confinement effect. In this work, we use first-principles calculations to systematically explore a novel nanospace constructed by placing a 2D graphitic carbon nitride (g-C 3 N 4 ) nanosheet over a Pt(111) surface. The confined catalytic activity in this nanospace is investigated using CO oxidation as a model reaction. With the inherent triangular pores in the g-C 3 N 4 overlayer being taken advantage of, molecules such as CO and O 2 can diffuse to adsorb on the Pt(111) surface underneath the g-C 3 N 4 overlayer. Moreover, the mechanism of intercalation is also elucidated, and the results reveal that the energy barrier depends mainly on the properties of the molecule and the channel. Importantly, the molecule-catalyst interaction can be tuned by the g-C 3 N 4 overlayer, considerably reducing the adsorption energy of CO on Pt(111) and leading to enhanced reactivity in CO oxidation. This work will provide important insight for constructing a promising nanoreactor in which the following is observed: The molecule intercalation is facile; the molecule-metal interaction is efficiently tuned; the metal-catalyzed reaction is promoted.

  12. Single molecule studies of surface-induced secondary structure in a model peptide

    Science.gov (United States)

    English, Douglas S.; Cunningham, Joy A.; Wehri, Sarah C.; Petrik, Amy F.; Okamoto, Kenji

    2004-10-01

    We have proposed using single molecule fluorescence resonant energy transfer (SM-FRET) to investigate the induction of secondary structure in model, surface-active peptides upon binding at an interface. The ability for SM-FRET to distinguish structural heterogeneity will offer a distinct advantage over traditional biophysical methods in these types of studies. Ensemble methods mask heterogeneity and only provide an average measure of secondary structural features. Because secondary structure contributes greatly to the energetics of dehydrating the amide backbone, detailed information of conformational distributions is crucial to the understanding of the thermodynamic cycle involved. Here we present results from our first efforts at using SM-FRET to study an amphipathic α-helix forming peptide immobilized at the solid-liquid interface between an aqueous solution and an octadecylsilane modified glass surface. This system serves as a model for future studies of peptide partitioning to lipid bilayers and other relevant interfaces.

  13. Active Particles on Curved Surfaces

    OpenAIRE

    Fily, Yaouen; Baskaran, Aparna; Hagan, Michael F.

    2016-01-01

    Recent studies have highlighted the sensitivity of active matter to boundaries and their geometries. Here we develop a general theory for the dynamics and statistics of active particles on curved surfaces and illustrate it on two examples. We first show that active particles moving on a surface with no ability to probe its curvature only exhibit steady-state inhomogeneities in the presence of orientational order. We then consider a strongly confined 3D ideal active gas and compute its steady-...

  14. Vibrational excitation in molecule--surface collisions due to temporary negative molecular ion formation

    International Nuclear Information System (INIS)

    Gadzuk, J.W.

    1983-01-01

    Inelastic electron scattering from gaseous and physisorbed diatomic molecules results in greatly enhanced vibrational overtone excitation if the incident electron has the appropriate energy to form a shape-resonance-induced temporary negative molecular ion. It is proposed here that due to the image potential lowering of the electron affinity level of a diatomic molecule in interaction with a metal surface, somewhere outside the surface an incident molecule would find its affinity level degenerate with or lower than the substrate Fermi level at which point a substrate electron could hop onto the molecule, in analogy with gas phase harpooning processes. A negative molecular ion is thus formed which remains until the molecular ion reflects from the surface and the affinity level rises above the Fermi level, thus permitting reverse electron hopping back into the metal. The lifetime of the molecular ion can be controlled by varying both the kinetic energy of the incident molecule and also the substrate work function. In analogy with the electron scattering events, greatly enhanced vibrational excitation of overtones is expected in the molecules of the scattered beam. Induced fluorescence probing of the vibrational state distribution should then yield fundamental information pertaining to the dynamics of charge transfer reactions and nonadiabatic effects in molecule--surface interactions. A theory of this phenomenon is here presented together with the numerical consequences for a model system designed to simulate N 2 or NO scattering from standard surface science metal surfaces

  15. DFT study on the interaction of TiO2 (001) surface with HCHO molecules

    Science.gov (United States)

    Wu, Guofei; Zhao, Cuihua; Guo, Changqing; Chen, Jianhua; Zhang, Yibing; Li, Yuqiong

    2018-01-01

    The interactions of formaldehyde (HCHO) molecule with TiO2 (001) surface were studied using density functional theory calculations. HCHO molecules are dissociated by the cleavage of Csbnd H bonds after adsorption on TiO2 surface. The strong interactions between HCHO melecules and TiO2 surface are largely attributed to the bonding of hydrogen of HCHO and oxygen of TiO2 surface, which is mainly from the hybridization of the H 1s, O 2p and O 2s. The newly formed Hsbnd O bonds cause the structure changes of TiO2 surface, and lead to the cleavage of Osbnd Ti bond of TiO2 surface. The Csbnd O bond that the dissociated remains of HCHO and newly formed Hsbnd O bond can be oxidized to form carbon dioxide and water in subsequent action by oxygen from the atomosphere. The charges transfer from HCHO to TiO2 surface, and the sum amount of the charges transferred from four HCHO molecules to TiO2 surface is bigger than that from one HCHO molecule to TiO2 surface due to the combined interaction of four HCHO molecules with TiO2 surface.

  16. Selection of conformational states in surface self-assembly for a molecule with eight possible pairs of surface enantiomers

    DEFF Research Database (Denmark)

    Nuermaimaiti, Ajiguli; Schultz-Falk, Vickie; Lind Cramer, Jacob

    2016-01-01

    Self-assembly of a molecule with many distinct conformational states, resulting in eight possible pairs of surface enantiomers, is investigated on a Au(111) surface under UHV conditions. The complex molecule is equipped with alkyl and carboxyl moieties to promote controlled self-assembly of lamel...... moieties in mirror-image domains of the lamellae structures, leading to selection of three out of the eight possible enantiomeric pairs....

  17. Surface topography of immunoglobulin molecules. I. Accessibility of aromatic chromophores of rabbit IgG.

    Science.gov (United States)

    Białkowska, H; Morawiecki, A

    1978-01-01

    Non-ionic detergent, Tween-20, was used in solvent perturbation studies of accessibility of aromatic amino acid residues in rabbit IgG molecules. It has been found that surface aromatic residues are localized in cervices inaccessible to perturbant molecules larger than ca. 10 A in diameter.

  18. Adsorption configuration effects on the surface diffusion of large organic molecules

    DEFF Research Database (Denmark)

    Sato, F.; Legoas, S.B.; Hummelink, F.

    2010-01-01

    results show that it has its physical basis on the interplay of the molecular hydrogens and the Cu(110) atomic spacing, which is a direct consequence of the matching between molecule and surface dimensions. This information could be used to find new molecules capable of displaying lock-and-key behavior...

  19. Interactions of molecules with surfaces. Progress report, 1 February 1985-31 January 1986

    International Nuclear Information System (INIS)

    Greene, E.F.

    1986-01-01

    The angular distributions of beams of Ne and Ar atoms scattered nearly elastically from LiF (100) at 294 K show structure that is obscured by inelastic scattering when the whole range of velocities leaving the crystal is recorded. Increased fluxes of neutral species in beams from an effusive source of alkali halide vapor observed when a beam of electrons is coaxial with the neutral beam are shown to be well accounted for by a model involving electron stimulated desorption of alkali atoms. A simple model is proposed for the compensation observed for changes of the preexponential factor and activation energy in rate coefficients for the desorption of molecules from surfaces undergoing surface phase transitions. The isomerization of perfluoroDewarbenzene to perfluorobenzene can be produced in yields of 10% after single energetic collisions with a surface of polytetrafluoroethylene. The yield of ions produced when a beam of Na atoms strikes a Si(111) surface is increased over the equilibrium value observed for thermal beams by a factor of 10 or more when the kinetic energy of the incoming atoms is increased to 14 eV. The yield is sensitive to the dynamics of electron exchange between the surface and the ion. 12 refs., 1 fig

  20. Renormalization of Optical Excitations in Molecules near a Metal Surface

    DEFF Research Database (Denmark)

    García Lastra, Juan Maria; Thygesen, Kristian Sommer

    2011-01-01

    The lowest electronic excitations of benzene and a set of donor-acceptor molecular complexes are calculated for the gas phase and on the Al(111) surface using the many-body Bethe-Salpeter equation. The energy of the charge-transfer excitations obtained for the gas phase complexes are found...... consequence we find that close to the metal surface the optical gap of benzene can exceed its quasiparticle gap. A classical image charge model for the screened Coulomb interaction can account for all these effects which, on the other hand, are completely missed by standard time-dependent density functional...

  1. Surface plasmon-enhanced optical trapping of quantum-dot-conjugated surface molecules on neurons cultured on a plasmonic chip

    Science.gov (United States)

    Miyauchi, Kohei; Tawa, Keiko; Kudoh, Suguru N.; Taguchi, Takahisa; Hosokawa, Chie

    2016-06-01

    Living neurons in a complex neuronal network communicate with each other through synaptic connections. The molecular dynamics of cell surface molecules localized at synaptic terminals is essential for functional connections via synaptic plasticity in the neuronal network. Here, we demonstrate surface-plasmon-resonance-based optical trapping using a plasmonic chip toward realizing effective manipulation of molecules on the surface of neurons. Surface-plasmon-enhanced optical trapping was evaluated by the fluorescence analysis of nanoparticles suspended in water and neural cell adhesion molecules (NCAMs) labeled with quantum dots (Q-dots) on rat hippocampal neurons. The motion of nanoparticles in water and the molecular dynamics of NCAMs on neuronal cells cultured on a plasmonic chip were constrained at the laser focus more effectively than those on a glass substrate because of the surface plasmon resonance effect.

  2. Nanocoating of titanium implant surfaces with organic molecules. Polysaccharides including glycosaminoglycans

    DEFF Research Database (Denmark)

    Gurzawska, Katarzyna Aleksandra; Svava, Rikke; Jørgensen, Niklas Rye

    2012-01-01

    Long-term stability of titanium implants are dependent on a variety of factors. Nanocoating with organic molecules is one of the method used to improve osseointegration. Nanoscale modification of titanium implants affects surface properties, such as hydrophilicity, biochemical bonding capacity...... with focus on polysaccharides including glycosaminoglycans, and how these molecules change surface properties, cell reactions and affect on osseointegartion. The included in vitro studies demonstrated increased cell adhesion, proliferation and mineralization of a number of the tested polysaccharide...

  3. Desorption dynamics of deuterium molecules from the Si(100)-(3x1) dideuteride surface.

    Science.gov (United States)

    Niida, T; Tsurumaki, H; Namiki, A

    2006-01-14

    We measured polar angle (theta)-resolved time-of-flight spectra of D2 molecules desorbing from the Si(100)-(3x1) dideuteride surface. The desorbing D2 molecules exhibit a considerable translational heating with mean desorption kinetic energies of approximately 0.25 eV, which is mostly independent of the desorption angles for 0 degreesdynamics of deuterium was discussed along the principle of detailed balance to predict their adsorption dynamics onto the monohydride Si surface.

  4. Signaling lymphocytic activation molecules Slam and cancers: friends or foes?

    Science.gov (United States)

    Fouquet, Gregory; Marcq, Ingrid; Debuysscher, Véronique; Bayry, Jagadeesh; Rabbind Singh, Amrathlal; Bengrine, Abderrahmane; Nguyen-Khac, Eric; Naassila, Mickael; Bouhlal, Hicham

    2018-03-23

    Signaling Lymphocytic Activation Molecules (SLAM) family receptors are initially described in immune cells. These receptors recruit both activating and inhibitory SH2 domain containing proteins through their Immunoreceptor Tyrosine based Switch Motifs (ITSMs). Accumulating evidence suggest that the members of this family are intimately involved in different physiological and pathophysiological events such as regulation of immune responses and entry pathways of certain viruses. Recently, other functions of SLAM, principally in the pathophysiology of neoplastic transformations have also been deciphered. These new findings may prompt SLAM to be considered as new tumor markers, diagnostic tools or potential therapeutic targets for controlling the tumor progression. In this review, we summarize the major observations describing the implications and features of SLAM in oncology and discuss the therapeutic potential attributed to these molecules.

  5. In Situ Detection of Organic Molecules on the Martian Surface With the Mars Organic Molecule Analyzer (MOMA) on Exomars 2018

    Science.gov (United States)

    Li, Xiang; Brinckerhoff, William B.; Pinnick, Veronica T; van Amerom, Friso H. W.; Danell, Ryan M.; Arevalo, Ricardo D., Jr.; Getty, Stephanie; Mahaffy, Paul R.

    2015-01-01

    The Mars Organic Molecule Analyzer (MOMA) investigation on the 2018 ExoMars rover will examine the chemical composition of samples acquired from depths of up to two meters below the martian surface, where organics may be protected from radiative and oxidative degradation. The MOMA instrument is centered around a miniaturized linear ion trap (LIT) that facilitates two modes of operation: i) pyrolysisgas chromatography mass spectrometry (pyrGC-MS); and, ii) laser desorptionionization mass spectrometry (LDI-MS) at ambient Mars pressures. The LIT also enables the structural characterization of complex molecules via complementary analytical capabilities, such as multi-frequency waveforms (i.e., SWIFT) and tandem mass spectrometry (MSMS). When combined with the complement of instruments in the rovers Pasteur Payload, MOMA has the potential to reveal the presence of a wide range of organics preserved in a variety of mineralogical environments, and to begin to understand the structural character and potential origin of those compounds.

  6. Manipulating individual dichlorotin phthalocyanine molecules on Cu(100) surface at room temperature by scanning tunneling microscopy

    International Nuclear Information System (INIS)

    Li, Chao; Xiang, Feifei; Wang, Zhongping; Liu, Xiaoqing; Jiang, Danfeng; Wang, Li; Wang, Guang; Zhang, Xueao; Chen, Wei

    2014-01-01

    Single molecule manipulations have been achieved on dichlorotin phthalocyanine(SnCl 2 Pc) molecules adsorbed on Cu (100) at room temperature. Scanning tunneling microscopy observations directly demonstrate that the individual SnCl 2 Pc molecules can be moved along the [100] direction on Cu(100) surface by employing a scanning tunneling microscope tip fixed at the special position of the molecules. The orientation of the molecule can be switched between two angles of ±28° with respect to the [011] surface direction in the same way. Dependences of the probability of molecular motion on the distances between the tip and the molecules reveal that the mechanism for such manipulation of a SnCl 2 Pc molecule is dominated by the repulsive interactions between the tip and the molecules. With the assistance of this manipulation process, a prototype molecular storage array with molecular orientation as information carrier and an artificial hydrogen bonded supramolecular structure have been constructed on the surface. (paper)

  7. Surface Chemistry Dependence of Mechanochemical Reaction of Adsorbed Molecules-An Experimental Study on Tribopolymerization of α-Pinene on Metal, Metal Oxide, and Carbon Surfaces.

    Science.gov (United States)

    He, Xin; Kim, Seong H

    2018-02-20

    Mechanochemical reactions between adsorbate molecules sheared at tribological interfaces can induce association of adsorbed molecules, forming oligomeric and polymeric products often called tribopolymers). This study revealed the role or effect of surface chemistry of the solid substrate in mechanochemical polymerization reactions. As a model reactant, α-pinene was chosen because it was known to readily form tribopolymers at the sliding interface of stainless steel under vapor-phase lubrication conditions. Eight different substrate materials were tested-palladium, nickel, copper, stainless steel, gold, silicon oxide, aluminum oxide, and diamond-like carbon (DLC). All metal substrates and DLC were initially covered with surface oxide species formed naturally in air or during the oxidative sample cleaning. It was found that the tribopolymerization yield of α-pinene is much higher on the substrates that can chemisorb α-pinene, compared to the ones on which only physisorption occurs. From the load dependence of the tribopolymerization yield, it was found that the surfaces capable of chemisorption give a smaller critical activation volume for the mechanochemical reaction, compared to the ones capable of physisorption only. On the basis of these observations and infrared spectroscopy analyses of the adsorbed molecules and the produced polymers, it was concluded that the mechanochemical reaction mechanisms might be different between chemically reactive and inert surfaces and that the chemical reactivity of the substrate surface greatly influences the tribochemical polymerization reactions of adsorbed molecules.

  8. The topological molecule: Its finite fluxes, exchange stability and minimal surfaces

    Science.gov (United States)

    Thomas, Gerald F.

    2016-03-01

    Molecules have at least one nontrivial topological property in common: their minimal surfaces of finite flux. This is why they are stable aggregates of atoms mutually engaged to varying degrees via Coulombic and exchange interactions in fealty to quantum mechanics on otherwise passive nuclear scaffolds. Isolated atoms do not have minimal surfaces but they do undergo exchange interactions. All surfaces implicitly defined by a molecule’s charge density are shown to have zero mean curvature and are consequently minimal surfaces. This finding extends to any potential of a molecule. The minimal surface is of importance in that it is indicative of a vanishing mean curvature whose measurement serves as a way of gauging the charge density or electrostatic potential’s local reliability, a quality assurance protocol absent in conventional crystallography but available to scanning force microscopy. The smaller the mean curvature of an atom, the more bonded is that atom in a molecule. The basis for this discovery is that implicit surfaces admit finite flux to cross them regardless of atomic affiliation, thus engendering exchange, correlation, and chemical bonding between the atoms in the underlying nuclear framework of a molecule. Finite flux in the charge density is a necessary condition for chemical bonding and the stability of molecules and is what makes the electron localization function (ELF) and the exchange-correlation functional (BLYP) useful.

  9. CHEMICAL ACTIVATION OF MOLECULES BY METALS: EXPERIMENTAL STUDIES OF ELECTRON DISTRIBUTIONS AND BONDING; FINAL

    International Nuclear Information System (INIS)

    LICHTENBERGER, DENNIS L.

    2002-01-01

    This research program is directed at obtaining detailed experimental information on the electronic interactions between metals and organic molecules. These interactions provide low energy pathways for many important chemical and catalytic processes. A major feature of the program is the continued development and application of our special high-resolution valence photoelectron spectroscopy (UPS), and high-precision X-ray core photoelectron spectroscopy (XPS) instrumentation for study of organometallic molecules in the gas phase. The study involves a systematic approach towards understanding the interactions and activation of bound carbonyls, C-H bonds, methylenes, vinylidenes, acetylides, alkenes, alkynes, carbenes, carbynes, alkylidenes, alkylidynes, and others with various monometal, dimetal, and cluster metal species. Supporting ligands include -aryls, alkoxides, oxides, and phosphines. We are expanding our studies of both early and late transition metal species and electron-rich and electron-poor environments in order to more completely understand the electronic factors that serve to stabilize particular organic fragments and intermediates on metals. Additional new directions for this program are being taken in ultra-high vacuum surface UPS, XPS, scanning tunneling microscopy (STM) and atomic force microscopy (AFM) experiments on both physisorbed and chemisorbed organometallic thin films. The combination of these methods provides additional electronic structure information on surface-molecule and molecule-molecule interactions. A very important general result emerging from this program is the identification of a close relationship between the ionization energies of the species and the thermodynamics of the chemical and catalytic reactions of these systems

  10. CHEMICAL ACTIVATION OF MOLECULES BY METALS: EXPERIMENTAL STUDIES OF ELECTRON DISTRIBUTIONS AND BONDING

    Energy Technology Data Exchange (ETDEWEB)

    LICHTENBERGER, DENNIS L.

    2002-03-26

    This research program is directed at obtaining detailed experimental information on the electronic interactions between metals and organic molecules. These interactions provide low energy pathways for many important chemical and catalytic processes. A major feature of the program is the continued development and application of our special high-resolution valence photoelectron spectroscopy (UPS), and high-precision X-ray core photoelectron spectroscopy (XPS) instrumentation for study of organometallic molecules in the gas phase. The study involves a systematic approach towards understanding the interactions and activation of bound carbonyls, C-H bonds, methylenes, vinylidenes, acetylides, alkenes, alkynes, carbenes, carbynes, alkylidenes, alkylidynes, and others with various monometal, dimetal, and cluster metal species. Supporting ligands include -aryls, alkoxides, oxides, and phosphines. We are expanding our studies of both early and late transition metal species and electron-rich and electron-poor environments in order to more completely understand the electronic factors that serve to stabilize particular organic fragments and intermediates on metals. Additional new directions for this program are being taken in ultra-high vacuum surface UPS, XPS, scanning tunneling microscopy (STM) and atomic force microscopy (AFM) experiments on both physisorbed and chemisorbed organometallic thin films. The combination of these methods provides additional electronic structure information on surface-molecule and molecule-molecule interactions. A very important general result emerging from this program is the identification of a close relationship between the ionization energies of the species and the thermodynamics of the chemical and catalytic reactions of these systems.

  11. Switching behavior of double-decker single molecule magnets on a metal surface

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Yingshuang; Schwoebel, Joerg; Hoffmann, Germar; Brede, Jens; Wiesendanger, Roland [University of Hamburg, Hamburg (Germany); Dillulo, Andrew [Ohio University, Athens (United States); Klyatskaya, Svetlana [Karlsruhe Institute of Technology, Karlsruhe (Germany); Ruben, Mario [Karlsruhe Institute of Technology, Karlsruhe (Germany); Universite de Strasbourg, Strasbourg (France)

    2011-07-01

    Single molecule magnets (SMM) are most promising materials for spin based molecular electronics. Due to their large magnetic anisotropy stabilized by inside chemical bonds, SMM can potentially be used for information storage at the single molecule level. For applications, it is of importance to adsorb the SMM onto surfaces and to study their subsequent conformational, electronic and magnetic properties. We have investigated the adsorption behavior of Tb and Dy based double-decker SMM on an Ir(111) surface with low temperature scanning tunneling microscopy and spectroscopy. It is found that Tb double-decker molecules bind tightly to the Ir(111) surface. By resonantly injecting tunneling electrons into its LUMO or HOMO state, the Tb double-decker molecule can be switched from a four-lobed structure to an eight-lobed structure. After switching, energy positions of the HOMO and LUMO states both shift closer to the Fermi level. Dy double-decker molecules also exhibit the same switching properties on the Ir(111) surface. The switching behavior of the molecules is tentatively attributed to a conformational change of the double-decker molecular frame.

  12. Influence of TiO{sub 2} Surface Properties on Water Pollution Treatment and Photocatalytic Activity

    Energy Technology Data Exchange (ETDEWEB)

    Zeng, Min [Southwest Univ. of Science and Technology, Mianyang (China)

    2013-03-15

    The titania surface showed different characteristics depending on the charge of the dye molecules. Compared with the MB molecules, the negatively charged MO molecules strongly adsorbed on the titania surface. Furthermore, the decomposition kinetics of the dye molecules by the photocatalytic activity also deepened with the charge of the dye molecules. The relation between the UV irradiation time and the molar ratio of the decomposed dye molecules followed the Avrami equation. According to the results of the analysis by using the Avrami equation, the MO molecules were decomposed on the titania particle surface. In contrast, the MB molecules were decomposed in the aqueous solution. The difference in kinetics was related to the interaction of the dye molecules and the titania surface. These preferential adsorption and decomposition characteristics will improve its applications in water pollution treatment.

  13. On-Demand Final State Control of a Surface-Bound Bistable Single Molecule Switch.

    Science.gov (United States)

    Garrido Torres, José A; Simpson, Grant J; Adams, Christopher J; Früchtl, Herbert A; Schaub, Renald

    2018-04-12

    Modern electronic devices perform their defined action because of the complete reliability of their individual active components (transistors, switches, diodes, and so forth). For instance, to encode basic computer units (bits) an electrical switch can be used. The reliability of the switch ensures that the desired outcome (the component's final state, 0 or 1) can be selected with certainty. No practical data storage device would otherwise exist. This reliability criterion will necessarily need to hold true for future molecular electronics to have the opportunity to emerge as a viable miniaturization alternative to our current silicon-based technology. Molecular electronics target the use of single-molecules to perform the actions of individual electronic components. On-demand final state control over a bistable unimolecular component has therefore been one of the main challenges in the past decade (1-5) but has yet to be achieved. In this Letter, we demonstrate how control of the final state of a surface-supported bistable single molecule switch can be realized. On the basis of the observations and deductions presented here, we further suggest an alternative strategy to achieve final state control in unimolecular bistable switches.

  14. Surface single-molecule dynamics controlled by entropy at low temperatures

    Science.gov (United States)

    Gehrig, J. C.; Penedo, M.; Parschau, M.; Schwenk, J.; Marioni, M. A.; Hudson, E. W.; Hug, H. J.

    2017-02-01

    Configuration transitions of individual molecules and atoms on surfaces are traditionally described using an Arrhenius equation with energy barrier and pre-exponential factor (attempt rate) parameters. Characteristic parameters can vary even for identical systems, and pre-exponential factors sometimes differ by orders of magnitude. Using low-temperature scanning tunnelling microscopy (STM) to measure an individual dibutyl sulfide molecule on Au(111), we show that the differences arise when the relative position of tip apex and molecule changes by a fraction of the molecule size. Altering the tip position on that scale modifies the transition's barrier and attempt rate in a highly correlated fashion, which results in a single-molecular enthalpy-entropy compensation. Conversely, appropriately positioning the STM tip allows selecting the operating point on the compensation line and modifying the transition rates. The results highlight the need to consider entropy in transition rates of single molecules, even at low temperatures.

  15. Attenuated total reflectance spectroscopy of coumarin organosilane molecules adsorbed on a fused silica surface

    International Nuclear Information System (INIS)

    Bratescu, Maria Antoaneta; Saito, Nagahiro; Takai, Osamu

    2010-01-01

    Attenuated total reflectance (ATR) spectroscopy was used to investigate the adsorption of coumarin organosilane molecules onto a fused silica surface. The difference between the absorption spectra of the molecules on the surface and in solution was explained by the interaction of the adsorbed coumarin organosilane molecules with the hydroxyl groups on the fused silica surface. This interaction produces a perturbation of the π electron distribution and the electronic transitions of the coumarin chromophore of the organosilane molecules adsorbed on the surface. From the kinetics adsorption curves, the calculated enthalpy values of 74.8 ± 5.2 kJ mol -1 and free energy of -38.22 ± 0.70 kJ mol -1 at 23 deg. C indicates a chemisorption process. The high sensitivity of ATR spectroscopy allows the detection of a monolayer formed by a 10 nM concentration of coumarin organosilane molecules, which covers more than half of the maximum surface coverage at 60 deg. C.

  16. A theoretical model for the scattering of I2 molecule from a perfluoropolyeter liquid surface

    Directory of Open Access Journals (Sweden)

    Leal Alexandre S.

    1999-01-01

    Full Text Available In order to simulate experimental results of scattering of an I2 beam from liquid perfluorpolyeter ( PFPE surface we developed a model potential for the gas-polymer interaction at the liquid surface and solved the dynamics of the collision process by the classical trajectory method. The energy transferred in the process to the vibrational mode of the I2 molecule and to the liquid surface was investigated as a function of potential parameters.

  17. Adsorption Study of a Water Molecule on Vacancy-Defected Nonpolar CdS Surfaces

    Science.gov (United States)

    2017-01-01

    A detailed understanding of the water–semiconductor interface is of major importance for elucidating the molecular interactions at the photocatalyst’s surface. Here, we studied the effect of vacancy defects on the adsorption of a water molecule on the (101̅0) and (112̅0) CdS surfaces, using spin-polarized density functional theory. We observed that the local spin polarization did not persist for most of the cationic vacancies on the surfaces, unlike in bulk, owing to surface reconstructions caused by displaced S atoms. This result suggests that cationic vacancies on these surfaces may not be the leading cause of the experimentally observed magnetism in CdS nanostructures. The surface vacancies are predominantly nonmagnetic except for one case, where a magnetic cationic vacancy is relatively stable due to constraints posed by the (101̅0) surface geometry. At this particular magnetic defect site, we found a very strong interaction with the H2O molecule leading to a case of chemisorption, where the local spin polarization vanishes concurrently. At the same defect site, adsorption of an O2 molecule was also simulated, and the results were found to be consistent with experimental electron paramagnetic resonance findings for powdered CdS. The anion vacancies on these surfaces were always found to be nonmagnetic and did not affect the water adsorption at these surfaces. PMID:28539988

  18. Active Free Surface Density Maps

    Science.gov (United States)

    Çelen, S.

    2016-10-01

    Percolation problems were occupied to many physical problems after their establishment in 1957 by Broadbent and Hammersley. They can be used to solve complex systems such as bone remodeling. Volume fraction method was adopted to set some algorithms in the literature. However, different rate of osteoporosis could be observed for different microstructures which have the same mass density, mechanical stimuli, hormonal stimuli and nutrition. Thus it was emphasized that the bone might have identical porosity with different specific surfaces. Active free surface density of bone refers the used total area for its effective free surface. The purpose of this manuscript is to consolidate a mathematical approach which can be called as “active free surface density maps” for different surface patterns and derive their formulations. Active free surface density ratios were calculated for different Archimedean lattice models according to Helmholtz free energy and they were compared with their site and bond percolation thresholds from the background studies to derive their potential probability for bone remodeling.

  19. Surface-Attached Molecules Control Staphylococcus aureus Quorum Sensing and Biofilm Development

    Science.gov (United States)

    Kim, Minyoung Kevin; Zhao, Aishan; Wang, Ashley; Brown, Zachary Z.; Muir, Tom W.; Stone, Howard A.; Bassler, Bonnie L.

    2017-01-01

    Bacteria use a process called quorum sensing to communicate and orchestrate collective behaviors including virulence factor secretion and biofilm formation. Quorum sensing relies on production, release, accumulation, and population-wide detection of signal molecules called autoinducers. Here, we develop concepts to coat surfaces with quorum-sensing-manipulation molecules as a method to control collective behaviors. We probe this strategy using Staphylococcus aureus. Pro- and anti-quorum-sensing molecules can be covalently attached to surfaces using click chemistry, where they retain their abilities to influence bacterial behaviors. We investigate key features of the compounds, linkers, and surfaces necessary to appropriately position molecules to interact with cognate receptors, and the ability of modified surfaces to resist long-term storage, repeated infections, host plasma components, and flow-generated stresses. Our studies highlight how this surface approach can be used to make colonization-resistant materials against S. aureus and other pathogens and how the approach can be adapted to promote beneficial behaviors of bacteria on surfaces. PMID:28530651

  20. Interface properties of organic molecules on metal surfaces; Grenzflaecheneigenschaften organischer Molekuele auf Metalloberflaechen

    Energy Technology Data Exchange (ETDEWEB)

    Karacuban, Hatice

    2010-01-28

    In this work, the growth of the archetype molecules CuPc and PTCDA was investigated on Cu(111). PTCDA was also studied on NaCl/Cu(111). The main experiments were carried out with a scanning tunneling microscope. Structural analysis of CuPc on Cu (111) is only possible at low temperatures, since at room temperature the molecules exhibit a high surface mobility. For the investigation of these structures and especially to enable scanning tunneling spectroscopy, a low-temperature scanning tunneling microscope was developed. Using this home built STM the experiments could be carried out at about 10 K. After the adsorption of CuPc on Cu (111) a substrate-induced symmetry reduction of the molecules can be observed in scanning tunneling microscopy. When the occupied states of the molecules are imaged, a switching between two distinct levels is found. These modifications are determined by the adsorption geometry of the molecules. Based on high resolution STM data, an on-top adsorption geometry of the CuPc-molecules on Cu (111)-substrate can be deducted. At low temperatures, two new superstructures of PTCDA on Cu(111) are observed. The molecules within these superstructures are tilted with respect to the substrate. Intermolecular interactions may be the crucial factor for the realignment of the molecules. If PTCDA molecules are adsorbed on a NaCl/Cu (111) substrate, at room temperature, also two new superstructures on the copper substrate were found. They indicate the formation of a metall-organic-complex. On top of the NaCl layer the molecules exclusively grow at polar NaCl step edges. This is an indication for electrostatic interaction between the PTCDA molecules and the NaCl layer. When the molecule density is further increased, a Vollmer-Weber growth sets in. If both molecules PTCDA and CuPc are present on the sample at the same time, local spectroscopy provides information on the metal-organic interface in direct comparison. The STS-results of CuPc/PTCDA on Cu (111

  1. Small Molecule Inhibitors Targeting Activator Protein 1 (AP-1)

    Science.gov (United States)

    2015-01-01

    Activator protein 1 (AP-1) is a pivotal transcription factor that regulates a wide range of cellular processes including proliferation, apoptosis, differentiation, survival, cell migration, and transformation. Accumulating evidence supports that AP-1 plays an important role in several severe disorders including cancer, fibrosis, and organ injury, as well as inflammatory disorders such as asthma, psoriasis, and rheumatoid arthritis. AP-1 has emerged as an actively pursued drug discovery target over the past decade. Excitingly, a selective AP-1 inhibitor T-5224 (51) has been investigated in phase II human clinical trials. Nevertheless, no effective AP-1 inhibitors have yet been approved for clinical use. Despite significant advances achieved in understanding AP-1 biology and function, as well as the identification of small molecules modulating AP-1 associated signaling pathways, medicinal chemistry efforts remain an urgent need to yield selective and efficacious AP-1 inhibitors as a viable therapeutic strategy for human diseases. PMID:24831826

  2. Desorption dynamics of deuterium molecules from the Si(100)-(3×1) dideuteride surface

    OpenAIRE

    Niida, T; Tsurumaki, Hiroshi; Namiki, Akira

    2006-01-01

    We measured polar angle ()-resolved time-of-flight spectra of D2 molecules desorbing from the Si(100)-(3×1) dideuteride surface. The desorbing D2 molecules exhibit a considerable translational heating with mean desorption kinetic energies of 0.25 eV, which is mostly independent of the desorption angles for 0°30°. The observed desorption dynamics of deuterium was discussed along the principle of detailed balance to predict their adsorption dynamics onto the monohydride Si surface.

  3. Ureaplasma diversum Genome Provides New Insights about the Interaction of the Surface Molecules of This Bacterium with the Host.

    Directory of Open Access Journals (Sweden)

    Lucas M Marques

    Full Text Available Whole genome sequencing and analyses of Ureaplasma diversum ATCC 49782 was undertaken as a step towards understanding U. diversum biology and pathogenicity. The complete genome showed 973,501 bp in a single circular chromosome, with 28.2% of G+C content. A total of 782 coding DNA sequences (CDSs, and 6 rRNA and 32 tRNA genes were predicted and annotated. The metabolic pathways are identical to other human ureaplasmas, including the production of ATP via hydrolysis of the urea. Genes related to pathogenicity, such as urease, phospholipase, hemolysin, and a Mycoplasma Ig binding protein (MIB-Mycoplasma Ig protease (MIP system were identified. More interestingly, a large number of genes (n = 40 encoding surface molecules were annotated in the genome (lipoproteins, multiple-banded antigen like protein, membrane nuclease lipoprotein and variable surface antigens lipoprotein. In addition, a gene encoding glycosyltransferase was also found. This enzyme has been associated with the production of capsule in mycoplasmas and ureaplasma. We then sought to detect the presence of a capsule in this organism. A polysaccharide capsule from 11 to 17 nm of U. diversum was observed trough electron microscopy and using specific dyes. This structure contained arabinose, xylose, mannose, galactose and glucose. In order to understand the inflammatory response against these surface molecules, we evaluated the response of murine macrophages J774 against viable and non-viable U. diversum. As with viable bacteria, non-viable bacteria were capable of promoting a significant inflammatory response by activation of Toll like receptor 2 (TLR2, indicating that surface molecules are important for the activation of inflammatory response. Furthermore, a cascade of genes related to the inflammasome pathway of macrophages was also up-regulated during infection with viable organisms when compared to non-infected cells. In conclusion, U. diversum has a typical ureaplasma genome and

  4. Ureaplasma diversum Genome Provides New Insights about the Interaction of the Surface Molecules of This Bacterium with the Host.

    Science.gov (United States)

    Marques, Lucas M; Rezende, Izadora S; Barbosa, Maysa S; Guimarães, Ana M S; Martins, Hellen B; Campos, Guilherme B; do Nascimento, Naíla C; Dos Santos, Andrea P; Amorim, Aline T; Santos, Verena M; Farias, Sávio T; Barrence, Fernanda  C; de Souza, Lauro M; Buzinhani, Melissa; Arana-Chavez, Victor E; Zenteno, Maria E; Amarante-Mendes, Gustavo P; Messick, Joanne B; Timenetsky, Jorge

    2016-01-01

    Whole genome sequencing and analyses of Ureaplasma diversum ATCC 49782 was undertaken as a step towards understanding U. diversum biology and pathogenicity. The complete genome showed 973,501 bp in a single circular chromosome, with 28.2% of G+C content. A total of 782 coding DNA sequences (CDSs), and 6 rRNA and 32 tRNA genes were predicted and annotated. The metabolic pathways are identical to other human ureaplasmas, including the production of ATP via hydrolysis of the urea. Genes related to pathogenicity, such as urease, phospholipase, hemolysin, and a Mycoplasma Ig binding protein (MIB)-Mycoplasma Ig protease (MIP) system were identified. More interestingly, a large number of genes (n = 40) encoding surface molecules were annotated in the genome (lipoproteins, multiple-banded antigen like protein, membrane nuclease lipoprotein and variable surface antigens lipoprotein). In addition, a gene encoding glycosyltransferase was also found. This enzyme has been associated with the production of capsule in mycoplasmas and ureaplasma. We then sought to detect the presence of a capsule in this organism. A polysaccharide capsule from 11 to 17 nm of U. diversum was observed trough electron microscopy and using specific dyes. This structure contained arabinose, xylose, mannose, galactose and glucose. In order to understand the inflammatory response against these surface molecules, we evaluated the response of murine macrophages J774 against viable and non-viable U. diversum. As with viable bacteria, non-viable bacteria were capable of promoting a significant inflammatory response by activation of Toll like receptor 2 (TLR2), indicating that surface molecules are important for the activation of inflammatory response. Furthermore, a cascade of genes related to the inflammasome pathway of macrophages was also up-regulated during infection with viable organisms when compared to non-infected cells. In conclusion, U. diversum has a typical ureaplasma genome and metabolism, and

  5. Imbalanced expression of functional surface molecules in regulatory and effector T cells in systemic lupus erythematosus

    International Nuclear Information System (INIS)

    Mesquita Júnior, D.; Cruvinel, W.M.; Araujo, J.A.P.; Salmazi, K.C.; Kallas, E.G.; Andrade, L.E.C.

    2014-01-01

    Regulatory T (TREG) cells play an important role in maintaining immune tolerance and avoiding autoimmunity. We analyzed the expression of membrane molecules in TREG and effector T cells in systemic lupus erythematosus (SLE). TREG and effector T cells were analyzed for the expression of CTLA-4, PD1, CD28, CD95, GITR, HLA-DR, OX40, CD40L, and CD45RO in 26 patients with active disease, 31 with inactive disease, and 26 healthy controls. TREG cells were defined as CD25 +/high CD127 Ø/low FoxP3 + , and effector T cells were defined as CD25 + CD127 + FoxP3 Ø . The ratio of TREG to effector T cells expressing GITR, PD1, HLA-DR, OX40, CD40L, and CD45RO was determined in the three groups. The frequency of TREG cells was similar in patients with SLE and controls. However, SLE patients had a decreased frequency of CTLA-4 + TREG and CD28 + TREG cells and an increased frequency of CD40L + TREG cells. There was a decrease in the TREG/effector-T ratio for GITR + , HLA-DR + , OX40 + , and CD45RO + cells, and an increased ratio of TREG/effector-T CD40L + cells in patients with SLE. In addition, CD40L + TREG cell frequency correlated with the SLE disease activity index (P=0.0163). In conclusion, our findings showed several abnormalities in the expression of functionally critical surface molecules in TREG and effector T cells in SLE that may be relevant to the pathogenesis of this disease

  6. Imbalanced expression of functional surface molecules in regulatory and effector T cells in systemic lupus erythematosus

    Energy Technology Data Exchange (ETDEWEB)

    Mesquita Júnior, D. [Disciplina de Reumatologia, Departamento de Medicina, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, SP (Brazil); Cruvinel, W.M. [Disciplina de Reumatologia, Departamento de Medicina, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, SP (Brazil); Departamento de Biomedicina, Universidade Católica de Goiás, Goiânia, GO (Brazil); Araujo, J.A.P. [Disciplina de Reumatologia, Departamento de Medicina, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, SP (Brazil); Salmazi, K.C.; Kallas, E.G. [Disciplina de Imunologia Clínica e Alergia, Departamento de Clínica Médica, Faculdade de Medicina, Universidade de São Paulo, São Paulo, SP (Brazil); Andrade, L.E.C. [Disciplina de Reumatologia, Departamento de Medicina, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, SP (Brazil)

    2014-08-22

    Regulatory T (TREG) cells play an important role in maintaining immune tolerance and avoiding autoimmunity. We analyzed the expression of membrane molecules in TREG and effector T cells in systemic lupus erythematosus (SLE). TREG and effector T cells were analyzed for the expression of CTLA-4, PD1, CD28, CD95, GITR, HLA-DR, OX40, CD40L, and CD45RO in 26 patients with active disease, 31 with inactive disease, and 26 healthy controls. TREG cells were defined as CD25{sup +/high}CD127{sup Ø/low}FoxP3{sup +}, and effector T cells were defined as CD25{sup +}CD127{sup +}FoxP3{sup Ø}. The ratio of TREG to effector T cells expressing GITR, PD1, HLA-DR, OX40, CD40L, and CD45RO was determined in the three groups. The frequency of TREG cells was similar in patients with SLE and controls. However, SLE patients had a decreased frequency of CTLA-4{sup +}TREG and CD28{sup +}TREG cells and an increased frequency of CD40L{sup +}TREG cells. There was a decrease in the TREG/effector-T ratio for GITR{sup +}, HLA-DR{sup +}, OX40{sup +}, and CD45RO{sup +} cells, and an increased ratio of TREG/effector-T CD40L{sup +} cells in patients with SLE. In addition, CD40L{sup +}TREG cell frequency correlated with the SLE disease activity index (P=0.0163). In conclusion, our findings showed several abnormalities in the expression of functionally critical surface molecules in TREG and effector T cells in SLE that may be relevant to the pathogenesis of this disease.

  7. Adsorption of the water molecule on monolayer graphene surface has effect on its optical properties

    International Nuclear Information System (INIS)

    Peng, Y F; Wang, J; Lu, Z S; Han, X Y

    2015-01-01

    The adsorption of water molecules on the surface of a monolayer graphene can be studied with the Materials Studio software and be applied density function theory from first principles. By studying the interaction of graphene with water molecule, it uses DFT (density function theory) with the PBE-GGA (the generalized gradient approximation of Perdew- Burke-Ernzerhof) and Periodic plane model, on the one hand working out the adsorption energy, and on the other hand getting related optical properties. It is shown that a single water molecule on graphene has very small adsorption energy, mainly owning to the van der Waals interactions. Graphene has high hydrophobic; adsorbed water molecule has little effect on the electronic structure of the graphene. The optical properties of the graphene have changed after the adsorption. (paper)

  8. Surface structures from low energy electron diffraction: Atoms, small molecules and an ordered ice film on metal surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Materer, Nicholas F. [Univ. of California, Berkeley, CA (United States)

    1995-09-01

    We investigated the surface bonding of various adsorbates (0, S, C2H3 and NO) along with the resulting relaxation of the Pt(111) surface using low energy electron diffiraction (LEED). LEED experiments have been performed on these ordered overlayers along with theoretical structural analysis using automated tensor LEED (ATLEED). The resulting surface structures of these ordered overlayers exhibit similar adsorbate-induced relaxations. In all cases the adsorbate occupies the fcc hollow site and induces an approximately 0.1 A buckling of the metal surface. The three metal atoms directly bonded to the adsorbate are ``pulled`` out of the surface and the metal atom that is not bound to the adsorbate is `pushed`` inward. In order to understand the reliability of such details, we have carried out a comprehensive study of various non-structural parameters used in a LEED computation. We also studied the adsorption of water on the Pt(lll) surface. We ordered an ultra thin ice film on this surface. The film`s surface is found to be the (0001) face of hexagonal ice. This surface is apparently terminated by a full-bilayer, in which the uppermost water molecules have large vibrational amplitudes even at temperatures as low as 90 K. We examined two other metal surfaces besides Pt(111): Ni(111) and Fe(lll). On Ni(111), we have studied the surface under a high coverage of NO. On both Ni(111) and Pt(111) NO molecules occupy the hollow sites and the N-0 bond distances are practically identical. The challenging sample preparation of an Fe(111) surface has been investigated and a successful procedure has been obtained. The small interlayer spacing found on Fe(111) required special treatment in the LEED calculations. A new ATLEED program has been developed to handle this surface.

  9. Theory of the reaction dynamics of small molecules on metal surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Jackson, Bret [Univ. of Massachusetts, Amherst, MA (United States)

    2016-09-09

    The objective of this project has been to develop realistic theoretical models for gas-surface interactions, with a focus on processes important in heterogeneous catalysis. The dissociative chemisorption of a molecule on a metal is a key step in many catalyzed reactions, and is often the rate-limiting step. We have explored the dissociative chemisorption of H2, H2O and CH4 on a variety of metal surfaces. Most recently, our extensive studies of methane dissociation on Ni and Pt surfaces have fully elucidated its dependence on translational energy, vibrational state and surface temperature, providing the first accurate comparisons with experimental data. We have explored Eley-Rideal and hot atom reactions of H atoms with H- and C-covered metal surfaces. H atom interactions with graphite have also been explored, including both sticking and Eley-Rideal recombination processes. Again, our methods made it possible to explain several experiments studying these reactions. The sticking of atoms on metal surfaces has also been studied. To help elucidate the experiments that study these processes, we examine how the reaction dynamics depend upon the nature of the molecule-metal interaction, as well as experimental variables such as substrate temperature, beam energy, angle of impact, and the internal states of the molecules. Electronic structure methods based on Density Functional Theory are used to compute each molecule-metal potential energy surface. Both time-dependent quantum scattering techniques and quasi-classical methods are used to examine the reaction or scattering dynamics. Much of our effort has been directed towards developing improved quantum methods that can accurately describe reactions, as well as include the effects of substrate temperature (lattice vibration).

  10. Non-additivity of molecule-surface van der Waals potentials from force measurements

    Science.gov (United States)

    Wagner, Christian; Fournier, Norman; Ruiz, Victor G.; Li, Chen; Müllen, Klaus; Rohlfing, Michael; Tkatchenko, Alexandre; Temirov, Ruslan; Tautz, F. Stefan

    2014-11-01

    Van der Waals (vdW) forces act ubiquitously in condensed matter. Despite being weak on an atomic level, they substantially influence molecular and biological systems due to their long range and system-size scaling. The difficulty to isolate and measure vdW forces on a single-molecule level causes our present understanding to be strongly theory based. Here we show measurements of the attractive potential between differently sized organic molecules and a metal surface using an atomic force microscope. Our choice of molecules and the large molecule-surface separation cause this attraction to be purely of vdW type. The experiment allows testing the asymptotic vdW force law and its validity range. We find a superlinear growth of the vdW attraction with molecular size, originating from the increased deconfinement of electrons in the molecules. Because such non-additive vdW contributions are not accounted for in most first-principles or empirical calculations, we suggest further development in that direction.

  11. Non-additivity of molecule-surface van der Waals potentials from force measurements.

    Science.gov (United States)

    Wagner, Christian; Fournier, Norman; Ruiz, Victor G; Li, Chen; Müllen, Klaus; Rohlfing, Michael; Tkatchenko, Alexandre; Temirov, Ruslan; Tautz, F Stefan

    2014-11-26

    Van der Waals (vdW) forces act ubiquitously in condensed matter. Despite being weak on an atomic level, they substantially influence molecular and biological systems due to their long range and system-size scaling. The difficulty to isolate and measure vdW forces on a single-molecule level causes our present understanding to be strongly theory based. Here we show measurements of the attractive potential between differently sized organic molecules and a metal surface using an atomic force microscope. Our choice of molecules and the large molecule-surface separation cause this attraction to be purely of vdW type. The experiment allows testing the asymptotic vdW force law and its validity range. We find a superlinear growth of the vdW attraction with molecular size, originating from the increased deconfinement of electrons in the molecules. Because such non-additive vdW contributions are not accounted for in most first-principles or empirical calculations, we suggest further development in that direction.

  12. Hydroxamic acid surface active agents

    Directory of Open Access Journals (Sweden)

    El-Sawy, A. A.

    2001-10-01

    Full Text Available p-Hydroxy phenyloctadecanol and p-hydroxy phenyloctadecanoic acid were used as new precursors for the preparation of surface active hydroxamic acid including different moles of propylene oxide. The hydroxamic acid was prepared by the reaction of propenoxylated products with sodium chloroacetate, followed by methyl esterification and the resultant product reacted with hydroxyl amine hydrochloride to give the hydroxamic acid. The structures of prepared hydroxamic acid were confirmed by spectroscopic study. The surface activity of prepared hydroxamic acid was studied; the results revealed that, the prepared hydroxamic acid has pronounced surface activity, the alcohol substrate shows a surface activity superior than the acid substrate.Se han utilizado el p-hidroxifeniloctadecanol y el ácido p-hidroxifeniloctadecanoico como nuevos precursores para la preparación de tensioactivos derivados del ácido hidroxámico, que incluyen diferentes moles de óxido de propileno. El ácido hidroxámico se preparó por reacción de los productos propenoxilados con cloroacetato sódico, seguido de la formación de ésteres metílicos, y los productos resultantes se hicieron reaccionar con clorhidrato de hidroxilamina para dar los derivados del ácido hidroxámico. Las estructuras de los derivados preparados del ácido hidroxámico, se confirmaron por técnicas espectroscópicas, estudiándose su actividad superficial cuyos resultados mostraron que dichos compuestos tenían un alto valor. La actividad superficial del sustrato alcohólico fue mayor que la del sustrato ácido.

  13. Marangoni Convection Assisted Single Molecule Detection with Nanojet Surface Enhanced Raman Spectroscopy.

    Science.gov (United States)

    Chang, Te-Wei; Wang, Xinhao; Mahigir, Amirreza; Veronis, Georgios; Liu, Gang Logan; Gartia, Manas Ranjan

    2017-08-25

    Many single-molecule (SM) label-free techniques such as scanning probe microscopies (SPM) and magnetic force spectroscopies (MFS) provide high resolution surface topography information, but lack chemical information. Typical surface enhanced Raman spectroscopy (SERS) systems provide chemical information on the analytes, but lack spatial resolution. In addition, a challenge in SERS sensors is to bring analytes into the so-called "hot spots" (locations where the enhancement of electromagnetic field amplitude is larger than 10 3 ). Previously described methods of fluid transport around hot spots like thermophoresis, thermodiffusion/Soret effect, and electrothermoplasmonic flow are either too weak or detrimental in bringing new molecules to hot spots. Herein, we combined the resonant plasmonic enhancement and photonic nanojet enhancemnet of local electric field on nonplanar SERS structures, to construct a stable, high-resolution, and below diffraction limit platform for single molecule label-free detection. In addition, we utilize Marangoni convection (mass transfer due to surface tension gradient) to bring new analytes into the hotspot. An enhancement factor of ∼3.6 × 10 10 was obtained in the proposed system. Rhodamine-6G (R6G) detection of up to a concentration of 10 -12 M, an improvement of two orders of magnitude, was achieved using the nanojet effect. The proposed system could provide a simple, high throughput SERS system for single molecule analysis at high spatial resolution.

  14. Adsorption and dissociation of oxygen molecules on Si(111)-(7×7) surface

    International Nuclear Information System (INIS)

    Niu, Chun-Yao; Wang, Jian-Tao

    2013-01-01

    The adsorption and dissociation of O 2 molecules on Si(111)-(7×7) surface have been studied by first-principles calculations. Our results show that all the O 2 molecular species adsorbed on Si(111)-(7×7) surface are unstable and dissociate into atomic species with a small energy barrier about 0.1 eV. The single O 2 molecule adsorption tends to form an ins×2 or a new metastable ins×2* structure on the Si adatom sites and the further coming O 2 molecules adsorb on those structures to produce an ad-ins×3 structure. The ad-ins×3 structure is indeed highly stable and kinetically limited for diving into the subsurface layer to form the ins×3-tri structure by a large barrier of 1.3 eV. Unlike the previous views, we find that all the ad-ins, ins×2, and ad-ins×3 structures show bright images, while the ins×2*, ins×3, and ins×3-tri structures show dark images. The proposed oxidation pathways and simulated scanning tunneling microscope images account well for the experimental results and resolve the long-standing confusion and issue about the adsorption and reaction of O 2 molecules on Si(111) surface

  15. Multiple atomic scale solid surface interconnects for atom circuits and molecule logic gates

    International Nuclear Information System (INIS)

    Joachim, C; Martrou, D; Gauthier, S; Rezeq, M; Troadec, C; Jie Deng; Chandrasekhar, N

    2010-01-01

    The scientific and technical challenges involved in building the planar electrical connection of an atomic scale circuit to N electrodes (N > 2) are discussed. The practical, laboratory scale approach explored today to assemble a multi-access atomic scale precision interconnection machine is presented. Depending on the surface electronic properties of the targeted substrates, two types of machines are considered: on moderate surface band gap materials, scanning tunneling microscopy can be combined with scanning electron microscopy to provide an efficient navigation system, while on wide surface band gap materials, atomic force microscopy can be used in conjunction with optical microscopy. The size of the planar part of the circuit should be minimized on moderate band gap surfaces to avoid current leakage, while this requirement does not apply to wide band gap surfaces. These constraints impose different methods of connection, which are thoroughly discussed, in particular regarding the recent progress in single atom and molecule manipulations on a surface.

  16. Syntenin-1 and ezrin proteins link activated leukocyte cell adhesion molecule to the actin cytoskeleton

    NARCIS (Netherlands)

    Tudor, Cicerone; te Riet, J.; Eich, C.; Harkes, R.; Smisdom, N.; Bouhuijzen Wenger, J.; Ameloot, M.; Holt, M.; Kanger, Johannes S.; Figdor, Carl; Cambi, A.; Subramaniam, Vinod

    2014-01-01

    Activated leukocyte cell adhesion molecule (ALCAM) is a type I transmembrane protein member of the immunoglobulin superfamily of cell adhesion molecules. Involved in important pathophysiological processes such as the immune response, cancer metastasis, and neuronal development, ALCAM undergoes both

  17. Synthesis of molecular complexes for small molecule activation

    International Nuclear Information System (INIS)

    Andrez, Julie

    2016-01-01

    The redox chemistry of f-elements is drawing the attention of inorganic chemists due to their unusual reaction pathways. Notably low-valent f-element complexes have been shown to be able to activate small molecules such as CO 2 and N 2 in mild conditions. Compared to d-block metals, f-elements present a coordination chemistry dominated by electrostatic interactions and steric constraints. Molecular complexes of f-elements could thus provide new catalytic routes to transform small molecules into valuable chemicals. However the redox chemistry of low valent f-elements is dominated by single-electron transfers while the reductions of CO 2 and N 2 require multi-electronic processes. Accordingly the first approach of this PhD work was the use of redox active ligands as electron reservoir to support f-element centres increasing the electron number available for reduction events. The coordination of uranium with tridentate Schiff base ligand was investigated and led to isolation of a dinuclear electron-rich species able to undertake up to eight-electron reduction combining the redox activity of the ligands and the uranium centres. In order to obtain electron-rich compounds potentially able to polarize the C=O bond of CO 2 , the synthesis of hetero-bimetallic species supported by salophen Schiff base ligand was also studied. In a second approach we have used bulky ligands with strong donor-character to tune the reducing abilities of low valent f-elements. In this case a bimolecular electron-transfer process is often observed. The reactivity of the U(III) siloxid complex [U(OSi(OtBu) 3 ) 4 K] was further investigated. Notably, reaction with Ph 3 PS led to the formation of a terminal U(IV) sulfide complex with multiple U-S bond which was analysed by DFT studies to better understand the bonding nature. Preliminary studies on the role of the counter-cation (M) in the system [U(OSi(OtBu) 3 ) 4 M] on the outcome of the reactivity with CS 2 and CO 2 have also been performed. The

  18. Single-Molecule Protein Folding: A Study of the Surface-Mediated Conformational Dynamics of a Model Amphipathic Peptide

    Science.gov (United States)

    Cunningham, Joy; English, Douglas

    2004-03-01

    Most surface-active polypeptides, composed of 10-50 amino acids, are devoid of well-defined tertiary structure. The conformation of these proteins is greatly dependent upon their environment and may assume totally different characteristics in an aqueous environment, in a detergent micelle, or in an organic solvent. Most antimicrobial peptides are helix-forming and are activated upon interaction with a membrane-mimicking environment. We are seeking to physically characterize the mechanism of membrane-peptide interaction through studying a simple model peptide, MT-1. MT-1 was designed as a nonhomologous analogue of melittin, the principle component in bee venom. We are using single molecule spectroscopy to examine the induction of secondary structure upon interaction of MT-1 with various membrane-mimicking interfaces. Specifically, we monitor coil-to-helix transition through single molecule fluorescence resonance energy transfer (sm-FRET) to determine conformational distributions of folded and unfolded peptides at an interface. Studies with MT-1 will focus upon the biologically relevant issues of orientation, aggregation, and folding at surfaces using both ensemble and single molecule experiments.

  19. Single molecule analysis of B cell receptor motion during signaling activation

    Science.gov (United States)

    Rey Suarez, Ivan; Koo, Peter; Zhou, Shu; Wheatley, Brittany; Song, Wenxia; Mochrie, Simon; Upadhyaya, Arpita

    B cells are an essential part of the adaptive immune system. They patrol the body for signs of infection in the form of antigen on the surface of antigen presenting cells. B cell receptor (BCR) binding to antigen induces a signaling cascade that leads to B cell activation and spreading. During activation, BCR form signaling microclusters that later coalesce as the cell contracts. We have studied the dynamics of BCRs on activated murine primary B cells using single particle tracking. The tracks are analyzed using perturbation expectation-maximization (pEM), a systems-level analysis, which allows identification of different short-time diffusive states from single molecule tracks. We identified four dominant diffusive states, two of which correspond to BCRs interacting with signaling molecules. For wild-type cells, the number of BCR in signaling states increases as the cell spreads and then decreases during cell contraction. In contrast, cells lacking the actin regulatory protein, N-WASP, are unable to contract and BCRs remain in the signaling states for longer times. These observations indicate that actin cytoskeleton dynamics modulate BCR diffusion and clustering. Our results provide novel information regarding the timescale of interaction between BCR and signaling molecules.

  20. Surface-enhanced Raman spectroscopy of dyes: from single molecules to the artists' canvas.

    Science.gov (United States)

    Wustholz, Kristin L; Brosseau, Christa L; Casadio, Francesca; Van Duyne, Richard P

    2009-09-14

    This perspective presents recent surface-enhanced Raman spectroscopy (SERS) studies of dyes, with applications to the fields of single-molecule spectroscopy and art conservation. First we describe the development and outlook of single-molecule SERS (SMSERS). Rather than providing an exhaustive review of the literature, SMSERS experiments that we consider essential for its future development are emphasized. Shifting from single-molecule to ensemble-averaged experiments, we describe recent efforts toward SERS analysis of colorants in precious artworks. Our intention is to illustrate through these examples that the forward development of SERS is dependent upon both fundamental (e.g., SMSERS) and applied (e.g., on-the-specimen SERS of historical art objects) investigations and that the future of SERS is very bright indeed.

  1. Mechanochemistry at Solid Surfaces: Polymerization of Adsorbed Molecules by Mechanical Shear at Tribological Interfaces.

    Science.gov (United States)

    Yeon, Jejoon; He, Xin; Martini, Ashlie; Kim, Seong H

    2017-01-25

    Polymerization of allyl alcohol adsorbed and sheared at a silicon oxide interface is studied using tribo-tests in vapor phase lubrication conditions and reactive molecular dynamics simulations. The load dependences of product formation obtained from experiments and simulations were consistent, indicating that the atomic-scale processes observable in the simulations were relevant to the experiments. Analysis of the experimental results in the context of mechanically assisted thermal reaction theory, combined with the atomistic details available from the simulations, suggested that the association reaction pathway of allyl alcohol molecules induced by mechanical shear is quite different from chemically induced polymerization reactions. Findings suggested that some degree of distortion of the molecule from its equilibrium state is necessary for mechanically induced chemical reactions to occur and such a distortion occurs during mechanical shear when molecules are covalently anchored to one of the sliding surfaces.

  2. Manipulating lipid bilayer material properties using biologically active amphipathic molecules

    Science.gov (United States)

    Ashrafuzzaman, Md; Lampson, M. A.; Greathouse, D. V.; Koeppe, R. E., II; Andersen, O. S.

    2006-07-01

    Lipid bilayers are elastic bodies with properties that can be manipulated/controlled by the adsorption of amphipathic molecules. The resulting changes in bilayer elasticity have been shown to regulate integral membrane protein function. To further understand the amphiphile-induced modulation of bilayer material properties (thickness, intrinsic monolayer curvature and elastic moduli), we examined how an enantiomeric pair of viral anti-fusion peptides (AFPs)—Z-Gly-D-Phe and Z-Gly-Phe, where Z denotes a benzyloxycarbonyl group, as well as Z-Phe-Tyr and Z-D-Phe-Phe-Gly—alters the function of enantiomeric pairs of gramicidin channels of different lengths in planar bilayers. For both short and long channels, the channel lifetimes and appearance frequencies increase as linear functions of the aqueous AFP concentration, with no apparent effect on the single-channel conductance. These changes in channel function do not depend on the chirality of the channels or the AFPs. At pH 7.0, the relative changes in channel lifetimes do not vary when the channel length is varied, indicating that these compounds exert their effects primarily by causing a positive-going change in the intrinsic monolayer curvature. At pH 4.0, the AFPs are more potent than at pH 7.0 and have greater effects on the shorter channels, indicating that these compounds now change the bilayer elastic moduli. When AFPs of different anti-fusion potencies are compared, the rank order of the anti-fusion activity and the channel-modifying activity is similar, but the relative changes in anti-fusion potency are larger than the changes in channel-modifying activity. We conclude that gramicidin channels are useful as molecular force transducers to probe the influence of small amphiphiles upon lipid bilayer material properties.

  3. Measuring binding kinetics of aromatic thiolated molecules with nanoparticles via surface-enhanced Raman spectroscopy

    Science.gov (United States)

    Devetter, Brent M.; Mukherjee, Prabuddha; Murphy, Catherine J.; Bhargava, Rohit

    2015-05-01

    Colloidal plasmonic nanomaterials, consisting of metals such as gold and silver, are excellent candidates for advanced optical probes and devices, but precise control over surface chemistry is essential for realizing their full potential. Coupling thiolated (R-SH) molecules to nanoprobe surfaces is a convenient and established route to tailor surface properties. The ability to dynamically probe and monitor the surface chemistry of nanoparticles in solution is essential for rapidly manufacturing spectroscopically tunable nanoparticles. In this study, we report the development of surface-enhanced Raman spectroscopy (SERS) as a method to monitor the kinetics of gold-thiolate bond formation on colloidal gold nanoparticles. A theoretical model combining SERS enhancement with the Beer-Lambert law is proposed to explain ensemble scattering and absorption effects in colloids during chemisorption. In order to maximize biological relevance and signal reproducibility, experiments used to validate the model focused on maintaining nanoparticle stability after the addition of water-soluble aromatic thiolated molecules. Our results indicate that ligand exchange on gold nanoparticles follow a first-order Langmuir adsorption model with rate constants on the order of 0.01 min-1. This study demonstrates an experimental spectroscopic method and theoretical model for monitoring binding kinetics that may prove useful for designing novel probes.Colloidal plasmonic nanomaterials, consisting of metals such as gold and silver, are excellent candidates for advanced optical probes and devices, but precise control over surface chemistry is essential for realizing their full potential. Coupling thiolated (R-SH) molecules to nanoprobe surfaces is a convenient and established route to tailor surface properties. The ability to dynamically probe and monitor the surface chemistry of nanoparticles in solution is essential for rapidly manufacturing spectroscopically tunable nanoparticles. In this

  4. Studies Relevent to Catalytic Activation Co & other small Molecules

    Energy Technology Data Exchange (ETDEWEB)

    Ford, Peter C

    2005-02-22

    Detailed annual and triannual reports describing the progress accomplished during the tenure of this grant were filed with the Program Manager for Catalysis at the Office of Basic Energy Sciences. To avoid unnecessary duplication, the present report will provide a brief overview of the research areas that were sponsored by this grant and list the resulting publications and theses based on this DOE supported research. The scientific personnel participating in (and trained by) this grant's research are also listed. Research carried out under this DOE grant was largely concerned with the mechanisms of the homogeneous catalytic and photocatalytic activation of small molecules such as carbon monoxide, dihydrogen and various hydrocarbons. Much of the more recent effort has focused on the dynamics and mechanisms of reactions relevant to substrate carbonylations by homogeneous organometallic catalysts. A wide range of modern investigative techniques were employed, including quantitative fast reaction methodologies such as time-resolved optical (TRO) and time-resolved infrared (TRIR) spectroscopy and stopped flow kinetics. Although somewhat diverse, this research falls within the scope of the long-term objective of applying quantitative techniques to elucidate the dynamics and understand the principles of mechanisms relevant to the selective and efficient catalytic conversions of fundamental feedstocks to higher value materials.

  5. Structure-property relationship of quinuclidinium surfactants--Towards multifunctional biologically active molecules.

    Science.gov (United States)

    Skočibušić, Mirjana; Odžak, Renata; Štefanić, Zoran; Križić, Ivana; Krišto, Lucija; Jović, Ozren; Hrenar, Tomica; Primožič, Ines; Jurašin, Darija

    2016-04-01

    Motivated by diverse biological and pharmacological activity of quinuclidine and oxime compounds we have synthesized and characterized novel class of surfactants, 3-hydroxyimino quinuclidinium bromides with different alkyl chains lengths (CnQNOH; n=12, 14 and 16). The incorporation of non conventional hydroxyimino quinuclidinium headgroup and variation in alkyl chain length affects hydrophilic-hydrophobic balance of surfactant molecule and thereby physicochemical properties important for its application. Therefore, newly synthesized surfactants were characterized by the combination of different experimental techniques: X-ray analysis, potentiometry, electrical conductivity, surface tension and dynamic light scattering measurements, as well as antimicrobial susceptibility tests. Comprehensive investigation of CnQNOH surfactants enabled insight into structure-property relationship i.e., way in which the arrangement of surfactant molecules in the crystal phase correlates with their solution behavior and biologically activity. The synthesized CnQNOH surfactants exhibited high adsorption efficiency and relatively low critical micelle concentrations. In addition, all investigated compounds showed very potent and promising activity against Gram-positive and clinically relevant Gram-negative bacterial strains compared to conventional antimicrobial agents: tetracycline and gentamicin. The overall results indicate that bicyclic headgroup with oxime moiety, which affects both hydrophilicity and hydrophobicity of CnQNOH molecule in addition to enabling hydrogen bonding, has dominant effect on crystal packing and physicochemical properties. The unique structural features of cationic surfactants with hydroxyimino quinuclidine headgroup along with diverse biological activity have made them promising structures in novel drug discovery. Obtained fundamental understanding how combination of different functionalities in a single surfactant molecule affects its physicochemical

  6. Average local ionization energies computed on the surfaces of some strained molecules

    International Nuclear Information System (INIS)

    Murray, J.S.; Seminario, J.M.; Politzer, P.; Sjoberg, P.

    1990-01-01

    An ab initio self-consistent-field molecular orbital (SCF-MO) procedure has been used to compute the average local ionization energies [bar I(r)] of some strained molecules on three-dimensional surfaces defined by the contour of electronic density equal to 0.002 electrons/bohr 3 . bar I(r) is rigorously defined within the framework of SCF-MO theory and can be interpreted as the average energy needed to ionize an electron at any point in the space of a molecule. Thus, the positions of the smallest (bar IOr) values (bar I S,min ) on the surfaces of molecules are the sites expected to be the most reactive to electrophiles. We find bar I S,min near the C-C bond midpoints of saturated three-membered, but not four-membered hydrocarbon rings. These bar I S,min are interpreted as reflecting the σ-aromatic character of the former. Our (bar IOr) data effectively provide a fingerprint characterizing saturated three-membered rings, which is useful, for example, in analyzing molecules such as [1.1.1]propellane. Our results for the latter are consistent with the interpretation of it having a biradical character, as has been suggested earlier

  7. Adsorption of squaraine molecules to Au(111) and Ag(001) surfaces

    Science.gov (United States)

    Luft, Maike; Groß, Boris; Schulz, Matthias; Lützen, Arne; Schiek, Manuela; Nilius, Niklas

    2018-02-01

    The adsorption of anilino squaraines, an important chromophore for the use in organic solar cells, to Ag(001) and Au(111) has been studied with scanning tunneling microscopy. Self-assembly into square building blocks with eight molecules per unit cell is revealed on the Ag surface, while no ordering effects occur on gold. The squaraine-silver interaction is mediated by the carbonyl and hydroxyl oxygens located in the center of the molecule. The intermolecular coupling, on the other hand, is governed by hydrogen bonds formed between the terminal isobutyl groups and oxygen species of adjacent molecules. The latter gets maximized by rotating the molecules by a few degrees against a perfect square alignment. A similar molecular pattern does not form on Au(111) due to symmetry mismatch. Moreover, the high electronegativity of gold reduces the directing effect of oxygen-metal bonds that trigger the ordering process on silver. As a consequence, only frustrated three-fold symmetric units that do not expand into an ordered molecular network are present on the gold surface.

  8. Exogenous cathepsin G upregulates cell surface MHC class I molecules on immune and glioblastoma cells.

    Science.gov (United States)

    Giese, Madleen; Turiello, Nadine; Molenda, Nicole; Palesch, David; Meid, Annika; Schroeder, Roman; Basilico, Paola; Benarafa, Charaf; Halatsch, Marc-Eric; Zimecki, Michal; Westhoff, Mike-Andrew; Wirtz, Christian Rainer; Burster, Timo

    2016-11-15

    Major histocompatibility complex (MHC) class I molecules present antigenic peptides to cytotoxic T cells. During an adaptive immune response, MHC molecules are regulated by several mechanisms including lipopolysaccharide (LPS) and interferon gamma (IFN-g). However, it is unclear whether the serine protease cathepsin G (CatG), which is generally secreted by neutrophils at the site of inflammation, might regulate MHC I molecules. We identified CatG, and to a higher extend CatG and lactoferrin (LF), as an exogenous regulator of cell surface MHC I expression of immune cells and glioblastoma stem cells. In addition, levels of MHC I molecules are reduced on dendritic cells from CatG deficient mice compared to their wild type counterparts. Furthermore, cell surface CatG on immune cells, including T cells, B cells, and NK cells triggers MHC I on THP-1 monocytes suggesting a novel mechanism for CatG to facilitate intercellular communication between infiltrating cells and the respective target cell. Subsequently, our findings highlight the pivotal role of CatG as a checkpoint protease which might force target cells to display their intracellular MHC I:antigen repertoire.

  9. Interface formation between hydrocarbon ring molecules and III-V semiconductor surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Passmann, Regina

    2008-08-15

    In this work a systematical study to investigate the adsorption structures of small hydrocarbon ring shaped molecules on III-V semiconductor surfaces with Photo-Emission Spectroscopy (PES), Reflectance Anisotropy Spectroscopy (RAS), Scanning Tunneling Microscopy (STM) as well as Low Electron Energy Diffraction (LEED) was performed. To investigate the influence of the surface structure in detail the surface dimer configuration to the adsorption process of organic molecules GaAs(001) surfaces, the c(4 x 4), the (2 x 4) and the (4 x 2) have been investigated as well as the adsorption of cyclopentene on the InP(001)(2 x 4) reconstructed surface. In the direct comparison it is shown that cyclopentene bonds to the InP(001)(2 x 4) surface via a cycloaddition like reaction. During this adsorption the double bond splits which is in contrast to the adsorption of cyclopentene on the GaAs(001) surfaces. Therefrom it is concluded that the surface geometry has an influence on the resulting adsorption structure. In order to investigate the influence of the intra-molecular double bonds, cyclopentene (one double bond), 1,4-cyclohexadiene (two double bonds) and benzene (three double bonds) were used for the characterization of the interface formation. With the investigations on the GaAs(001) reconstructed surfaces it was shown that a dependency of the bonding configuration on the intra-molecular double bonds exists. During the adsorption of cyclopentene no evidence was found that the double bond has to be involved in the interface formation while during the adsorption of 1,4-cyclohexadiene and benzene the double bonds are involved. Furthermore it was found that a bonding to As atoms of the surface is more likely than a bonding to Ga atoms. (orig.)

  10. Interface formation between hydrocarbon ring molecules and III-V semiconductor surfaces

    International Nuclear Information System (INIS)

    Passmann, Regina

    2008-01-01

    In this work a systematical study to investigate the adsorption structures of small hydrocarbon ring shaped molecules on III-V semiconductor surfaces with Photo-Emission Spectroscopy (PES), Reflectance Anisotropy Spectroscopy (RAS), Scanning Tunneling Microscopy (STM) as well as Low Electron Energy Diffraction (LEED) was performed. To investigate the influence of the surface structure in detail the surface dimer configuration to the adsorption process of organic molecules GaAs(001) surfaces, the c(4 x 4), the (2 x 4) and the (4 x 2) have been investigated as well as the adsorption of cyclopentene on the InP(001)(2 x 4) reconstructed surface. In the direct comparison it is shown that cyclopentene bonds to the InP(001)(2 x 4) surface via a cycloaddition like reaction. During this adsorption the double bond splits which is in contrast to the adsorption of cyclopentene on the GaAs(001) surfaces. Therefrom it is concluded that the surface geometry has an influence on the resulting adsorption structure. In order to investigate the influence of the intra-molecular double bonds, cyclopentene (one double bond), 1,4-cyclohexadiene (two double bonds) and benzene (three double bonds) were used for the characterization of the interface formation. With the investigations on the GaAs(001) reconstructed surfaces it was shown that a dependency of the bonding configuration on the intra-molecular double bonds exists. During the adsorption of cyclopentene no evidence was found that the double bond has to be involved in the interface formation while during the adsorption of 1,4-cyclohexadiene and benzene the double bonds are involved. Furthermore it was found that a bonding to As atoms of the surface is more likely than a bonding to Ga atoms. (orig.)

  11. Revisiting the Challenges in Fabricating Uniform Coatings with Polyfunctional Molecules on High Surface Energy Materials

    Directory of Open Access Journals (Sweden)

    Stephanie Oyola-Reynoso

    2015-12-01

    Full Text Available Modifying the chemistry of a surface has been widely used to influence interfacial properties of a material or nature of interaction between two materials. This article provides an overview on the role of polyfunctional molecules, specifically silanes, in surface modification of polar surfaces (bearing soft nucleophiles. An emphasis on the mechanism of the reaction in the presence of adsorbed water, where the modifying reagents are hydrolysable, is discussed. To highlight the complexity of the reaction, modification of paper with trichlorosilanes is highlighted. Preparation of hydrophobic cellulosic paper, and structure–property relations under different treatment conditions is used to highlight that a monolayer is not always formed during the surface modification. Gel-formation via step-growth polymerization suggests that at the right monomer:adsorbed water ratio, a monolayer will not form but rather self-assembly driven particle formation will occur leading to a textured surface. The review highlights recent work indicating that the focus on monolayer formation, is at the very least, not always the case but gel formation, with concomitant self-assembly, might be the culprit in understanding challenges associated with the use of polyfunctional molecules in surface modification.

  12. The effect of oxygen molecule adsorption on lead iodide perovskite surface by first-principles calculation

    Science.gov (United States)

    Ma, Xia-Xia; Li, Ze-Sheng

    2018-01-01

    Oxygen molecule has a negative effect on perovskite solar cells, which has been investigated experimentally. However, detailed theoretical research is still rare. This study presents a microscopic view to reveal the interaction mechanism between O2 and perovskite based on the first-principles calculation. The results show that O2 is adsorbed on the (100) surface of MAPbI3 perovskite mainly by Van der Waals force. O2 adsorption makes the MAPbI3 surface generate a small number of positive charges, which leads to the increase of the work function of the MAPbI3 surface. This is in agreement with the experimental measurement. And increased work function of MAPbI3 surface is not beneficial to electron transfer from perovskite to electronic extraction layer (such as TiO2). Comparison of the density of states (DOS) of the clean (100) surface and the adsorbed system shows that an in-gap state belonging to O2 appears, which can explain the phenomenon observed from experiments that electron transfers from the surface of perovskite to O2 to form superoxide. The theoretical power conversion efficiency of the system with and without O2 adsorption is evaluated, and it turns out that the power conversion efficiency of the system with O2 adsorption is slightly lower than that of the system without O2 adsorption. This result indicates that avoiding the introduction of O2 molecules between perovskite and electronic extraction layer is beneficial to the perovskite solar cell.

  13. Nano-sensing of the orientation of fluorescing molecules with active coated nano-particles

    DEFF Research Database (Denmark)

    Arslanagic, Samel; Ziolkowski, Richard W.

    2015-01-01

    The potential of using active coated nano-particles to determine the orientation of fluorescing molecules is reported. By treating each fluorescing molecule as an electric Hertzian dipole, single and multiple fluorescing molecules emitting coherently and incoherently in various orientations...... are considered in the presence of active coated nano-particles. It is demonstrated that in addition to offering a means to determine the orientation of a single molecule or the over-all orientation of the molecules surrounding it, the nature of the far-field response from the active coated nano-particles...

  14. Collisions of ideal gas molecules with a rough/fractal surface. A computational study.

    Science.gov (United States)

    Panczyk, Tomasz

    2007-02-01

    The frequency of collisions of ideal gas molecules (argon) with a rough surface has been studied. The rough/fractal surface was created using random deposition technique. By applying various depositions, the roughness of the surface was controlled and, as a measure of the irregularity, the fractal dimensions of the surfaces were determined. The surfaces were next immersed in argon (under pressures 2 x 10(3) to 2 x 10(5) Pa) and the numbers of collisions with these surfaces were counted. The calculations were carried out using a simplified molecular dynamics simulation technique (only hard core repulsions were assumed). As a result, it was stated that the frequency of collisions is a linear function of pressure for all fractal dimensions studied (D = 2, ..., 2.5). The frequency per unit pressure is quite complex function of the fractal dimension; however, the changes of that frequency with the fractal dimension are not strong. It was found that the frequency of collisions is controlled by the number of weakly folded sites on the surfaces and there is some mapping between the shape of adsorption energy distribution functions and this number of weakly folded sites. The results for the rough/fractal surfaces were compared with the prediction given by the Langmuir-Hertz equation (valid for smooth surface), generally the departure from the Langmuir-Hertz equation is not higher than 48% for the studied systems (i.e. for the surfaces created using the random deposition technique).

  15. Sustainable production of biologically active molecules of marine based origin.

    Science.gov (United States)

    Murray, Patrick M; Moane, Siobhan; Collins, Catherine; Beletskaya, Tanya; Thomas, Olivier P; Duarte, Alysson W F; Nobre, Fernando S; Owoyemi, Ifeloju O; Pagnocca, Fernando C; Sette, L D; McHugh, Edward; Causse, Eric; Pérez-López, Paula; Feijoo, Gumersindo; Moreira, Ma T; Rubiolo, Juan; Leirós, Marta; Botana, Luis M; Pinteus, Susete; Alves, Celso; Horta, André; Pedrosa, Rui; Jeffryes, Clayton; Agathos, Spiros N; Allewaert, Celine; Verween, Annick; Vyverman, Wim; Laptev, Ivan; Sineoky, Sergei; Bisio, Angela; Manconi, Renata; Ledda, Fabio; Marchi, Mario; Pronzato, Roberto; Walsh, Daniel J

    2013-09-25

    The marine environment offers both economic and scientific potential which are relatively untapped from a biotechnological point of view. These environments whilst harsh are ironically fragile and dependent on a harmonious life form balance. Exploitation of natural resources by exhaustive wild harvesting has obvious negative environmental consequences. From a European industry perspective marine organisms are a largely underutilised resource. This is not due to lack of interest but due to a lack of choice the industry faces for cost competitive, sustainable and environmentally conscientious product alternatives. Knowledge of the biotechnological potential of marine organisms together with the development of sustainable systems for their cultivation, processing and utilisation are essential. In 2010, the European Commission recognised this need and funded a collaborative RTD/SME project under the Framework 7-Knowledge Based Bio-Economy (KBBE) Theme 2 Programme 'Sustainable culture of marine microorganisms, algae and/or invertebrates for high value added products'. The scope of that project entitled 'Sustainable Production of Biologically Active Molecules of Marine Based Origin' (BAMMBO) is outlined. Although the Union is a global leader in many technologies, it faces increasing competition from traditional rivals and emerging economies alike and must therefore improve its innovation performance. For this reason innovation is placed at the heart of a European Horizon 2020 Strategy wherein the challenge is to connect economic performance to eco performance. This article provides a synopsis of the research activities of the BAMMBO project as they fit within the wider scope of sustainable environmentally conscientious marine resource exploitation for high-value biomolecules. Copyright © 2013 Elsevier B.V. All rights reserved.

  16. Single NdPc2 molecules on surfaces. Adsorption, interaction, and molecular magnetism

    International Nuclear Information System (INIS)

    Fahrendorf, Sarah

    2013-01-01

    They have huge potential for application in molecular-spin-transistors, molecular-spinvalves, and molecular quantum computing. SMMs are characterized by high spin ground states with zero-field splitting leading to high relaxation barriers and long relaxation times. A relevant class of molecules are the lanthanide double-decker phthalocyanines (LaPc 2 ) with only one metal atom sandwiched between two organic phthalocyanine (Pc) ligands. For envisaged spintronic applications it is important to understand the interaction between the molecules and the substrate and its influence on the electronic and magnetic properties. The subject of this thesis is the investigation of the adsorbed neodymium double-decker phthalocyanine (NdPc 2 ) by means of low temperature scanning tunneling microscopy and spectroscopy (STM and STS). The molecules are deposited by sublimation onto different substrates. It is observed that a large fraction of the double-decker molecules decomposes during deposition. The decomposition probability strongly depends on the chosen substrate. Therefore it is concluded that the substrate modifies the electronic structure of the molecule leading to a stabilization or destabilization of the molecular entity. Charge transfer from the surface to the molecule is identified as a potential stabilizing mechanism. The electronic and magnetic properties are investigated in detail for adsorbed NdPc 2 molecules on Cu(100). The results of the experimental study are compared to state-of-the-art density functional theory calculations performed by our colleagues from the Peter Gruenberg Institute (PGI-1) at the Forschungszentrum Juelich. Interestingly, the lower Pc ring of the molecule hybridizes intensely with the substrate leading to strong chemisorption of the molecule, while the upper Pc ring keeps its molecular type electronic states, which can be energetically shifted by an external electric field. Importantly, it is possible to get direct access to the spin

  17. Single NdPc{sub 2} molecules on surfaces. Adsorption, interaction, and molecular magnetism

    Energy Technology Data Exchange (ETDEWEB)

    Fahrendorf, Sarah

    2013-01-24

    They have huge potential for application in molecular-spin-transistors, molecular-spinvalves, and molecular quantum computing. SMMs are characterized by high spin ground states with zero-field splitting leading to high relaxation barriers and long relaxation times. A relevant class of molecules are the lanthanide double-decker phthalocyanines (LaPc{sub 2}) with only one metal atom sandwiched between two organic phthalocyanine (Pc) ligands. For envisaged spintronic applications it is important to understand the interaction between the molecules and the substrate and its influence on the electronic and magnetic properties. The subject of this thesis is the investigation of the adsorbed neodymium double-decker phthalocyanine (NdPc{sub 2}) by means of low temperature scanning tunneling microscopy and spectroscopy (STM and STS). The molecules are deposited by sublimation onto different substrates. It is observed that a large fraction of the double-decker molecules decomposes during deposition. The decomposition probability strongly depends on the chosen substrate. Therefore it is concluded that the substrate modifies the electronic structure of the molecule leading to a stabilization or destabilization of the molecular entity. Charge transfer from the surface to the molecule is identified as a potential stabilizing mechanism. The electronic and magnetic properties are investigated in detail for adsorbed NdPc{sub 2} molecules on Cu(100). The results of the experimental study are compared to state-of-the-art density functional theory calculations performed by our colleagues from the Peter Gruenberg Institute (PGI-1) at the Forschungszentrum Juelich. Interestingly, the lower Pc ring of the molecule hybridizes intensely with the substrate leading to strong chemisorption of the molecule, while the upper Pc ring keeps its molecular type electronic states, which can be energetically shifted by an external electric field. Importantly, it is possible to get direct access to the

  18. Microassay for measurement of binding of radiolabelled ligands to cell surface molecules

    International Nuclear Information System (INIS)

    Woof, J.M.; Burton, D.R.

    1988-01-01

    An improved technique for measuring the binding of radiolabelled ligands to cell surface molecules has been developed by modification of a procedure using centrifugation through a water-immiscible oil to separate free and cell-bound ligand. It maximises the percentage of ligand bound since cell-bound and free ligand can be separated easily and reproducibly even when very small reaction volumes are used. This permits low levels of ligand radiolabelling and relatively low numbers of cells to be used

  19. Toward single-molecule detection with sensors based on propagating surface plasmons

    Czech Academy of Sciences Publication Activity Database

    Kvasnička, Pavel; Chadt, Karel; Vala, Milan; Bocková, Markéta; Homola, Jiří

    2012-01-01

    Roč. 37, č. 2 (2012), s. 163-165 ISSN 0146-9592 R&D Projects: GA AV ČR KAN200670701; GA MŠk OC09058; GA MŠk(CZ) LH11102 Institutional research plan: CEZ:AV0Z20670512 Keywords : optical biosenzor * single molecule * surface plasmon microscopy Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 3.385, year: 2012

  20. SEM visualization of glycosylated surface molecules using lectin-coated microspheres

    Science.gov (United States)

    Duke, J.; Janer, L.; Campbell, M.

    1985-01-01

    There are several techniques currently used to localize glycosylated surface molecules by scanning electron microscopy (Grinnell, 1980; Molday, 1976; Linthicum and Sell, 1975; Nicolson, 1974; Lo Buglio, et al, 1972). A simple and rapid method, using a modification of Grinnell's technique is reported here. Essentially, microspheres coated with Concavalin A are used to bind to glycosylated regions of the palatal shelf epithelium and are visualized in the scanning electron microscope (SEM).

  1. Measuring the force of single protein molecule detachment from surfaces with AFM.

    Science.gov (United States)

    Tsapikouni, Theodora S; Missirlis, Yannis F

    2010-01-01

    Atomic force microscopy (AFM) was used to measure the non-specific detachment force of single fibrinogen molecules from glass surfaces. The identification of single unbinding events was based on the characteristics of the parabolic curves, recorded during the stretching of protein molecules. Fibrinogen molecules were covalently bound to Si(3)N(4) AFM tips, previously modified with 3-aminopropyl-dimethyl-ethoxysilane, through a homobifunctional poly(ethylene glycol) linker bearing two hydroxysulfosuccinimide esters. The most probable detachment force was found to be 210 pN, when the tip was retracting with a velocity of 1400 nm/s, while the distribution of the detachment distances indicated that the fibrinogen chain can be elongated beyond the length of the physical conformation before detachment. The dependence of the most probable detachment force on the loading rate was examined and the dynamics of fibrinogen binding to the surface were found amenable to the simple expression of the Bell-Evans theory. The theory's expansion, however, by incorporating the concept of the rupture of parallel residue-surface bonds could only describe the detachment of fibrinogen for a small number of such bonds. Finally, the mathematical expression of the Worm-Like Chain model was used to fit the stretching curves before rupture and two interpretations are suggested for the description of the AFM curves with multiple detachment events.

  2. Study of the Adsorption of Atoms and Molecules on Silicon Surfaces: Crystallographics and Electronic Structure

    International Nuclear Information System (INIS)

    Bengio, Silvina

    2003-01-01

    This thesis work has been concerned with adsorption properties of silicon surfaces.The atomic and electronic structure of molecules and atoms adsorbed on Si has been investigated by means of photoemission experiments combined with synchrotron radiation.The quantitative atomic structure determination was held applying the photoelectron diffraction technique.This technique is sensible to the local structure of a reference atomic specie and has elemental and chemical-state specificity.This approach has been applied to three quite different systems with different degrees of complexity, Sb/Si(111) √3x √3R30 0 , H 2 O/Si(100)2x1 and NH 3 /Si(111)7x7.Our results show that Sb which forms a ( √3√3)R30 0 phase produces a bulklike-terminated Si(111)1x1 substrate free of stacking faults.Regarding the atomic structure of its interface, this study strongly favours the T4-site milkstool model over the H3 one.An important aspect regarding the H 2 O/Si(100)(2x1) system was establishing the limits of precision with which one can determine not only the location of the adsorbed hydroxyl (OH) species, but also the extent to which this adsorption modifes the asymmetric dimers of the clean surface to which it is bonded.On the Si(111)(7x7) surface the problem is particularly complex because there are several different potentially active sites for NH3 adsorption and fragmentation.The application of the PhD method, however, has shown that the majority of the N atoms are on so-called 'rest atom' sites when deposited at RT.This is consistent with the N in the NH2 chemical state.This investigation represents the first quantitative structural study of any molecular adsorbate on the complex Si(111)(7x7) surface.This atomic structures determination shows the PhD is a powerful tool for the atomic structure determination.The molecular systems interacting with the active sites of the substrate fragments producing a short-range order surface.This long-range disorder is produced by the

  3. Dynamics and mass accommodation of HCl molecules on sulfuric acid-water surfaces.

    Science.gov (United States)

    Behr, P; Scharfenort, U; Ataya, K; Zellner, R

    2009-09-28

    A molecular beam technique has been used to study the dynamics and mass accommodation of HCl molecules in collision with sulfuric acid-water surfaces. The experiments were performed by directing a nearly mono-energetic beam of HCl molecules onto a continuously renewed liquid film of 54-76 wt% sulfuric acid at temperatures between 213 K and 243 K. Deuterated sulfuric acid was used to separate sticking but non-reactive collisions from those that involved penetration through the phase boundary followed by dissociation and recombination with D+. The results indicate that the mass accommodation of HCl on sulfuric acid-water surfaces decreases sharply with increasing acidity over the concentration range 54-76 wt%. Using the capillary wave theory of mass accommodation this effect is explained by a change of the surface dynamics. Regarding the temperature dependence it is found that the mass accommodation of HCl increases with increasing temperature and is limited by the bulk phase viscosity and driven by the restoring forces of the surface tension. These findings imply that under atmospheric conditions the uptake of HCl from the gas phase depends crucially on the bulk phase parameters of the sulfuric acid aerosol.

  4. The specificity of targeted vaccines for APC surface molecules influences the immune response phenotype.

    Directory of Open Access Journals (Sweden)

    Gunnveig Grødeland

    Full Text Available Different diseases require different immune responses for efficient protection. Thus, prophylactic vaccines should prime the immune system for the particular type of response needed for protection against a given infectious agent. We have here tested fusion DNA vaccines which encode proteins that bivalently target influenza hemagglutinins (HA to different surface molecules on antigen presenting cells (APC. We demonstrate that targeting to MHC class II molecules predominantly induced an antibody/Th2 response, whereas targeting to CCR1/3/5 predominantly induced a CD8(+/Th1 T cell response. With respect to antibodies, the polarizing effect was even more pronounced upon intramuscular (i.m delivery as compared to intradermal (i.d. vaccination. Despite these differences in induced immune responses, both vaccines protected against a viral challenge with influenza H1N1. Substitution of HA with ovalbumin (OVA demonstrated that polarization of immune responses, as a consequence of APC targeting specificity, could be extended to other antigens. Taken together, the results demonstrate that vaccination can be tailor-made to induce a particular phenotype of adaptive immune responses by specifically targeting different surface molecules on APCs.

  5. Surface active monomers synthesis, properties, and application

    CERN Document Server

    Borzenkov, Mykola

    2014-01-01

    This brief includes information on the background?of and development of synthesis of various types of surface active monomers. The authors explain the importance of utilization of surface active monomers for creation of surface active polymers? and the various biomedical applications of such compounds . This brief introduces techniques for the synthesis of novel types of surface active monomers, their colloidal and polymerizable properties and application for needs of medicine and biology.

  6. Delta self-consistent field method to obtain potential energy surfaces of excited molecules on surfaces

    DEFF Research Database (Denmark)

    Gavnholt, Jeppe; Olsen, Thomas; Engelund, Mads

    2008-01-01

    is a density-functional method closely resembling standard density-functional theory (DFT), the only difference being that in Delta SCF one or more electrons are placed in higher lying Kohn-Sham orbitals instead of placing all electrons in the lowest possible orbitals as one does when calculating the ground......-photoemission spectroscopy measurements. This comparison shows that the modified Delta SCF method gives results in close agreement with experiment, significantly closer than the comparable methods. For N2 adsorbed on ruthenium (0001) we map out a two-dimensional part of the potential energy surfaces in the ground state...

  7. Transport properties of water molecules confined between hydroxyapaptite surfaces: A Molecular dynamics simulation approach

    Science.gov (United States)

    Prakash, Muthuramalingam; Lemaire, Thibault; Di Tommaso, Devis; de Leeuw, Nora; Lewerenz, Marius; Caruel, Matthieu; Naili, Salah

    2017-10-01

    Water diffusion in the vicinity of hydroxyapatite (HAP) crystals is a key issue to describe biomineralization process. In this study, a configuration of parallel HAP platelets mimicking bone nanopores is proposed to characterize the nanoscopic transport properties of water molecules at HAP-water surface and interfaces using various potential models such as combination of the Core-Shell (CS) model, Lennard-Jones (LJ) potentials with SPC or SPC/E water models. When comparing all these potentials models, it appears that the core-shell potential for HAP together with the SPC/E water model more accurately predicts the diffusion properties of water near HAP surface. Moreover, we have been able to put into relief the possibility of observing hydroxyl (OH-) ion dissociation that modifies the water structure near the HAP surface.

  8. Structural Basis for Selective Small Molecule Kinase Inhibition of Activated c-Met

    Energy Technology Data Exchange (ETDEWEB)

    Rickert, Keith W.; Patel, Sangita B.; Allison, Timothy J.; Byrne, Noel J.; Darke, Paul L.; Ford, Rachael E.; Guerin, David J.; Hall, Dawn L.; Kornienko, Maria; Lu, Jun; Munshi, Sanjeev K.; Reid, John C.; Shipman, Jennifer M.; Stanton, Elizabeth F.; Wilson, Kevin J.; Young, Jonathon R.; Soisson, Stephen M.; Lumb, Kevin J. (Merck)

    2012-03-15

    The receptor tyrosine kinase c-Met is implicated in oncogenesis and is the target for several small molecule and biologic agents in clinical trials for the treatment of cancer. Binding of the hepatocyte growth factor to the cell surface receptor of c-Met induces activation via autophosphorylation of the kinase domain. Here we describe the structural basis of c-Met activation upon autophosphorylation and the selective small molecule inhibiton of autophosphorylated c-Met. MK-2461 is a potent c-Met inhibitor that is selective for the phosphorylated state of the enzyme. Compound 1 is an MK-2461 analog with a 20-fold enthalpy-driven preference for the autophosphorylated over unphosphorylated c-Met kinase domain. The crystal structure of the unbound kinase domain phosphorylated at Tyr-1234 and Tyr-1235 shows that activation loop phosphorylation leads to the ejection and disorder of the activation loop and rearrangement of helix {alpha}C and the G loop to generate a viable active site. Helix {alpha}C adopts a orientation different from that seen in activation loop mutants. The crystal structure of the complex formed by the autophosphorylated c-Met kinase domain and compound 1 reveals a significant induced fit conformational change of the G loop and ordering of the activation loop, explaining the selectivity of compound 1 for the autophosphorylated state. The results highlight the role of structural plasticity within the kinase domain in imparting the specificity of ligand binding and provide the framework for structure-guided design of activated c-Met inhibitors.

  9. Novel Molecular Non-Volatile Memory: Application of Redox-Active Molecules

    OpenAIRE

    Hao Zhu; Qiliang Li

    2015-01-01

    This review briefly describes the development of molecular electronics in the application of non-volatile memory. Molecules, especially redox-active molecules, have become interesting due to their intrinsic redox behavior, which provides an excellent basis for low-power, high-density and high-reliability non-volatile memory applications. Recently, solid-state non-volatile memory devices based on redox-active molecules have been reported, exhibiting fast speed, low operation voltage, excellent...

  10. Molecules-in-molecules fragment-based method for the calculation of chiroptical spectra of large molecules: Vibrational circular dichroism and Raman optical activity spectra of alanine polypeptides.

    Science.gov (United States)

    Jose, K V Jovan; Raghavachari, Krishnan

    2016-12-01

    The molecules-in-molecules (MIM) fragment-based method has recently been adapted to evaluate the chiroptical (vibrational circular dichroism [VCD] and Raman optical activity [ROA]) spectra of large molecules such as peptides. In the MIM-VCD and MIM-ROA methods, the relevant higher energy derivatives of the parent molecule are assembled from the corresponding derivatives of smaller fragment subsystems. In addition, the missing long-range interfragment interactions are accounted at a computationally less expensive level of theory (MIM2). In this work we employed the MIM-VCD and MIM-ROA fragment-based methods to explore the evolution of the chiroptical spectroscopic characteristics of 3 10 -helix, α-helix, β-hairpin, γ-turn, and β-extended conformers of gas phase polyalanine (chain length n = 6-14). The different conformers of polyalanine show distinctive features in the MIM chiroptical spectra and the associated spectral intensities increase with evolution of system size. For a better understanding the site-specific effects on the vibrational spectra, isotopic substitutions were also performed employing the MIM method. An increasing redshift with the number of isotopically labeled 13 C=O functional groups in the peptide molecule was seen. For larger polypeptides, we implemented the two-step-MIM model to circumvent the high computational expense associated with the evaluation of chiroptical spectra at a high level of theory using large basis sets. The chiroptical spectra of α-(alanine) 20 polypeptide obtained using the two-step-MIM model, including continuum solvation effects, show good agreement with the full calculations and experiment. This benchmark study suggests that the MIM-fragment approach can assist in predicting and interpreting chiroptical spectra of large polypeptides. © 2016 Wiley Periodicals, Inc.

  11. Doping effects of surface functionalization on graphene with aromatic molecule and organic solvents

    Science.gov (United States)

    Wu, Guangfu; Tang, Xin; Meyyappan, M.; Lai, King Wai Chiu

    2017-12-01

    Aromatic molecule functionalization plays a key role in the development of graphene field-effect transistors (G-FETs) for bio-detection. We have investigated the doping effects of surface functionalization and its influence on the carrier mobility of graphene. The aromatic molecule (1-pyrenebutanoic acid succinimidyl ester, PBASE), which is widely used as a linker to anchor bio-probes, was employed here to functionalize graphene. Dimethyl formamide (DMF) and methanol (CH3OH) were used as two solvents to dissolve PBASE. Raman spectra showed that both PBASE and these two solvents imposed doping effects on graphene. The PBASE was stably immobilized on the graphene surface, which was confirmed by the new peak at around 1623.5 cm-1 and the disordered D peak at 1350 cm-1. Electrical measurements and Fermi level shift analysis further revealed that PBASE imposes a p-doping effect while DMF and CH3OH impose an n-doping effect. More importantly, CH3OH causes a smaller reduction in the carrier mobility of G-FETs (from 1095.6 cm2/V s to 802.4 cm2/V s) than DMF (from 1640.4 cm2/V s to 5.0 cm2/V s). Therefore, CH3OH can be regarded as a better solvent for the PBASE functionalization. This careful study on the influence of organic solvents on graphene during PBASE functionalization process provides an effective approach to monitor the surface functionalization of graphene.

  12. Diverse redox-active molecules bearing O-, S-, or Se-terminated tethers for attachment to silicon in studies of molecular information storage.

    Science.gov (United States)

    Balakumar, Arumugham; Lysenko, Andrey B; Carcel, Carole; Malinovskii, Vladimir L; Gryko, Daniel T; Schweikart, Karl-Heinz; Loewe, Robert S; Yasseri, Amir A; Liu, Zhiming; Bocian, David F; Lindsey, Jonathan S

    2004-03-05

    A molecular approach to information storage employs redox-active molecules tethered to an electroactive surface. Attachment of the molecules to electroactive surfaces requires control over the nature of the tether (linker and surface attachment group). We have synthesized a collection of redox-active molecules bearing different linkers and surface anchor groups in free or protected form (hydroxy, mercapto, S-acetylthio, and Se-acetylseleno) for attachment to surfaces such as silicon, germanium, and gold. The molecules exhibit a number of cationic oxidation states, including one (ferrocene), two [zinc(II)porphyrin], three [cobalt(II)porphyrin], or four (lanthanide triple-decker sandwich compound). Electrochemical studies of monolayers of a variety of the redox-active molecules attached to Si(100) electrodes indicate that molecules exhibit a regular mode of attachment (via a Si-X bond, X = O, S, or Se), relatively homogeneous surface organization, and robust reversible electrochemical behavior. The acetyl protecting group undergoes cleavage during the surface deposition process, enabling attachment to silicon via thio or seleno groups without handling free thiols or selenols.

  13. Bacteroidales Secreted Antimicrobial Proteins Target Surface Molecules Necessary for Gut Colonization and Mediate Competition In Vivo

    Directory of Open Access Journals (Sweden)

    Kevin G. Roelofs

    2016-08-01

    Full Text Available We recently showed that human gut Bacteroidales species secrete antimicrobial proteins (BSAPs, and we characterized in vitro the first such BSAP produced by Bacteroides fragilis. In this study, we identified a second potent BSAP produced by the ubiquitous and abundant human gut species Bacteroides uniformis. The two BSAPs contain a membrane attack complex/perforin (MACPF domain but share very little sequence similarity. We identified the target molecules of BSAP-sensitive cells and showed that each BSAP targets a different class of surface molecule: BSAP-1 targets an outer membrane protein of sensitive B. fragilis strains, and BSAP-2 targets the O-antigen glycan of lipopolysaccharide (LPS of sensitive B. uniformis strains. Species-wide genomic and phenotypic analyses of B. fragilis and B. uniformis showed that BSAP-producing strains circumvent killing by synthesizing an orthologous nontargeted surface molecule. The BSAP genes are adjacent to the gene(s encoding their target replacements, suggesting coacquisition. Using a gnotobiotic mouse competitive-colonization model, we found that the BSAP surface targets are important for colonization of the mammalian gut, thereby explaining why they are maintained in sensitive strains and why they were replaced rather than deleted in BSAP-producing strains. Using isogenic BSAP-producing, -sensitive, and -resistant strains, we show that a BSAP-producing strain outcompetes a sensitive strain but not a resistant strain in the mammalian gut. Human gut metagenomic datasets reveal that BSAP-1-sensitive strains do not cooccur with BSAP-1-producing strains in human gut microbiotas, further supporting the idea that BSAPs are important competitive factors with relevance to the strain-level composition of the human gut microbiota.

  14. The adsorption and dissociation of water molecule on goethite (010) surface: A DFT approach

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Long, E-mail: shuweixia@ouc.edu.cn [Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Ocean University of China, College of Chemistry and Chemical Engineering (China); Xiu, Fangyuan [Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Ocean University of China, College of Chemistry and Chemical Engineering (China); Qiu, Meng [Qingdao Institute of Bioenergy and Bioprocess Technology (China); Xia, Shuwei; Yu, Liangmin [Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Ocean University of China, College of Chemistry and Chemical Engineering (China)

    2017-01-15

    Graphical abstract: The optimized structure of hydrated goethite (010) surface with medium water coverage (water density about 6.7 H{sub 2}O/nm{sup 2}). - Highlights: • Stable adsorption and dissociation structure of H{sub 2}O on goethite (010) surface was investigated by DFT. • Reasonable path for water dissociation was proposed by transitional state analysis. • The mechanism of water adsorption on goethite and binding nature were revealed by PDOS. - Abstract: Using density functional theory (DFT) calculation, we investigate the configuration, stability and electronic properties of fresh cleaved (010) goethite surface (Pnma) and this surface exposed to water monolayer at low, medium and high coverage. Water is predicted to be chemisorbed to the surface, together with the surface reconstruction. The interaction energy of the most stable configuration of both low and medium coverage per water molecule is almost the same (−1.17 eV), while that of high coverage is much lower (less than 1.03 eV). It indicates that highly hydrated surface is less stable. PDOS analysis reveals the adsorption of H{sub 2}O is due to the formation of Fe−O bond, caused by overlapping of Fe's 3d and O's 2p orbitals. Dissociation processes at low and medium water coverage are non-spontaneous; while at high coverage, it can undertake spontaneously both thermodynamically and dynamically. The dissociation paths of all three water coverage are the similar. The proton from one adsorbed water is likely to dissociate to bind to the vicinal surface μ{sub 3}−O as an intermediate product; the proton belonged to μ{sub 3}−O transferred to the neighbor surface μ{sub 2}−O as the dissociative configuration.

  15. Surface plasmon-coupled emission from shaped PMMA films doped with fluorescence molecules.

    Science.gov (United States)

    Zhang, D G; Moh, K J; Yuan, X-C

    2010-06-07

    Surface plasmon-coupled emission from shaped PMMA films doped with randomly oriented fluorescence molecules was investigated. Experimental results show that for different shapes, such as triangle or circular structures, the SPCE ring displays different intensity patterns. For a given shape, it was observed that the relative position and polarization of an incident laser spot on the shaped PMMA can be used to adjust the fluorescence intensity distribution of the SPCE ring. The proposed method enables controlling the fluorescence emission in azimuthal direction in addition to the radial angle controlled by common SPCE, which will further enhances the fluorescence collection efficiency and has applications in fluorescence sensing, imaging and so on.

  16. Electron collisions with atoms, ions, molecules, and surfaces: Fundamental science empowering advances in technology

    Science.gov (United States)

    Bartschat, Klaus; Kushner, Mark J.

    2016-06-01

    Electron collisions with atoms, ions, molecules, and surfaces are critically important to the understanding and modeling of low-temperature plasmas (LTPs), and so in the development of technologies based on LTPs. Recent progress in obtaining experimental benchmark data and the development of highly sophisticated computational methods is highlighted. With the cesium-based diode-pumped alkali laser and remote plasma etching of Si3N4 as examples, we demonstrate how accurate and comprehensive datasets for electron collisions enable complex modeling of plasma-using technologies that empower our high-technology-based society.

  17. Strategies for creating antifouling surfaces using selfassembled poly(ethylene glycol) thiol molecules

    DEFF Research Database (Denmark)

    Lokanathan, Arcot R.

    2011-01-01

    process. The PEG SAM backfilled with OEG molecules was tested for resistance towards serum adsorption and bacterial attachment, and was found to better resist fouling compared to PEG SAM that had not been backfilled. The second strategy involved PEG grafting using supercritical carbon dioxide (SFC), which...... biofilms forming on the surfaces of equipment to avoid contamination of their products. In addition to posing a health problem, biofilms also pose technical problems, such as corrosion and reduced water flow in technical water systems. Removal of a biofilm is very tedious and sometimes even impossible...

  18. Single-molecule characterization and engineering of the surfaces of nucleic acid sensors

    Science.gov (United States)

    Josephs, Eric Alan

    The advent of personalized medicine will require biosensors capable of reliably detecting small levels of disease biomarkers. In microarrays and sensors for nucleic acids, hybridization events between surface-tethered DNA probes and the nucleic acids of interest (targets) are transduced into a detectable signal. However, target-binding ultimately occurs as a result of molecular motions and interactions between the probe and target at the nanometer scale, and common characterization methods either lack the resolution to characterize the sensors at this scale or provide only limited information about their interactions with their nanoscale chemical environment. In this dissertation I argue that an impediment to the development of more reliable and practical biosensors is the lack of knowledge and control of the nanometer length-scale structure of biosensor surfaces, which has a profound impact on molecular recognition and reactions for detection. After reviewing the fundamental surface chemistry and structural motifs of biosensors in Chapter 1, in Chapter 2 I use electrochemical atomic force microscopy (EC-AFM) to characterize in situ a common class of model nucleic acid sensors---thiolated DNA attached to a gold electrode which has been passivated by an alkanethiol self-assembled monolayer---with single-molecule resolution. This level of detail allows me to observe both the conformations of individual probes and their spatial distribution at the nanoscale, then determine how these are affected by assembly conditions, probe structure, and interactions with co-adsorbates. I also determine how these nanoscale details affect the dynamic response of probes to electric fields, which have been commonly used in sensing schemes, and ultimately the ability of the surface-tethered probes to bind with target nucleic acids. In Chapter 3, I demonstrate and optimize the nanoscale patterning of individual DNA molecules into isolated, chemically well-defined niches on the surface

  19. Method and apparatus for enhanced sequencing of complex molecules using surface-induced dissociation in conjunction with mass spectrometric analysis

    Science.gov (United States)

    Laskin, Julia [Richland, WA; Futrell, Jean H [Richland, WA

    2008-04-29

    The invention relates to a method and apparatus for enhanced sequencing of complex molecules using surface-induced dissociation (SID) in conjunction with mass spectrometric analysis. Results demonstrate formation of a wide distribution of structure-specific fragments having wide sequence coverage useful for sequencing and identifying the complex molecules.

  20. Cell surface adhesion molecules and cytokine profiles in primary progressive multiple sclerosis

    DEFF Research Database (Denmark)

    Ukkonen, Maritta; Wu, Xingchen; Reipert, Birgit

    2007-01-01

    OBJECTIVE: We evaluated the utility of adhesion molecule (AM) and cytokine/chemokine expressions in blood and cerebrospinal fluid (CSF) as markers of disease activity in primary progressive multiple sclerosis (PPMS). METHODS: The expressions of AMs and the levels of 17 cytokines in patients...... with PPMS (n = 25) were compared with those in secondary progressive MS (SPMS) (n = 18) and controls (n =11) and correlated with the volumes of focal and atrophic changes on MRI. RESULTS: The expressions of very late activation antigen 4 (VLA-4), lymphocyte function-associated antigen 1 (LFA-1...

  1. Interaction of mineral surfaces with simple organic molecules by diffuse reflectance IR spectroscopy (DRIFT)

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, Joan E.; Kelley, Michael J.

    2008-06-01

    Diffuse reflectance Fourier-transform infrared spectroscopy (DRIFTS) was used to characterize multi-layers of lysine, glutamic acid and salicylic acid on -alumina and kaolinite surfaces. The results agreed well with those previously obtained by ATR-IR in aqueous media where available, indicating that DRIFT may be regarded as effectively an in-situ spectroscopy for these materials. In the case of salicylic acid adsorption onto γ-alumina, DRIFTS was used to identify monolayer coverage and to detect molecules down to coverage of 3% of a monolayer. The spectroscopic results as to coverage were confirmed by analysis of the solutions used for treatment. The spectra obtained allowed identification of changes in the bonding environment with increasing surface coverage. DRIFTS, offers several advantages in terms of materials, experimental technique and data treatment, motivating further investigations.

  2. A Raman spectroscopy study on the effects of intermolecular hydrogen bonding on water molecules absorbed by borosilicate glass surface

    Science.gov (United States)

    Li, Fabing; Li, Zhanlong; Wang, Ying; Wang, Shenghan; Wang, Xiaojun; Sun, Chenglin; Men, Zhiwei

    2018-05-01

    The structural forms of water/deuterated water molecules located on the surface of borosilicate capillaries have been first investigated in this study on the basis of the Raman spectral data obtained at different temperatures and under atmospheric pressure for molecules in bulk and also for molecules absorbed by borosilicate glass surface. The strongest two fundamental bands locating at 3063 cm-1 (2438 cm-1) in the recorded Raman spectra are assigned here to the Osbnd H (Osbnd D) bond stretching vibrations and they are compared with the corresponding bands observed at 3124 cm-1 (2325 cm-1) in the Raman spectrum of ice Ih. Our spectroscopic observations have indicated that the structure of water and deuterated water molecules on borosilicate surface is similar to that of ice Ih (hexagonal phase of ice). These observations have also indicated that water molecules locate on the borosilicate surface so as to construct a bilayer structure and that strong and weak intermolecular hydrogen bonds are formed between water/deuterated molecules and silanol groups on borosilicate surface. In accordance with these findings, water and deuterated water molecules at the interface of capillary have a higher melting temperature.

  3. A Raman spectroscopy study on the effects of intermolecular hydrogen bonding on water molecules absorbed by borosilicate glass surface.

    Science.gov (United States)

    Li, Fabing; Li, Zhanlong; Wang, Ying; Wang, Shenghan; Wang, Xiaojun; Sun, Chenglin; Men, Zhiwei

    2018-05-05

    The structural forms of water/deuterated water molecules located on the surface of borosilicate capillaries have been first investigated in this study on the basis of the Raman spectral data obtained at different temperatures and under atmospheric pressure for molecules in bulk and also for molecules absorbed by borosilicate glass surface. The strongest two fundamental bands locating at 3063cm -1 (2438cm -1 ) in the recorded Raman spectra are assigned here to the OH (OD) bond stretching vibrations and they are compared with the corresponding bands observed at 3124cm -1 (2325cm -1 ) in the Raman spectrum of ice Ih. Our spectroscopic observations have indicated that the structure of water and deuterated water molecules on borosilicate surface is similar to that of ice Ih (hexagonal phase of ice). These observations have also indicated that water molecules locate on the borosilicate surface so as to construct a bilayer structure and that strong and weak intermolecular hydrogen bonds are formed between water/deuterated molecules and silanol groups on borosilicate surface. In accordance with these findings, water and deuterated water molecules at the interface of capillary have a higher melting temperature. Copyright © 2018. Published by Elsevier B.V.

  4. Do surfaces of positive electrostatic potential on different halogen derivatives in molecules attract? like attracting like!

    Science.gov (United States)

    Varadwaj, Arpita; Varadwaj, Pradeep R; Yamashita, Koichi

    2018-03-15

    Coulomb's law states that like charges repel, and unlike charges attract. However, it has recently been theoretically revealed that two similarly charged conducting spheres will almost always attract each other when both are in close proximity. Using multiscale first principles calculations, we illustrate practical examples of several intermolecular complexes that are formed by the consequences of attraction between positive atomic sites of similar or dissimilar electrostatic surface potential on interacting molecules. The results of the quantum theory of atoms in molecules and symmetry adapted perturbation theory support the attraction between the positive sites, characterizing the F•••X (X = F, Cl, Br) intermolecular interactions in a series of 20 binary complexes as closed-shell type, although the molecular electrostatic surface potential approach does not (a failure!). Dispersion that has an r -6 dependence, where r is the equilibrium distance of separation, is found to be the sole driving force pushing the two positive sites to attract. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  5. Nanometer-scale discernment of field emission from tungsten surface with single carbon monoxide molecule

    Science.gov (United States)

    Matsunaga, Soichiro; Suwa, Yuji; Katagiri, Souichi

    2017-12-01

    Unusual quantized beam fluctuations were found in the emission current from a cold-field emitter (CFE) operating in an extremely high vacuum of 10-10 Pa. To clarify the microscopic mechanism behind these fluctuations, we developed a new calculation method to evaluate the field emission from a heterogeneous surface under a strong electric field of 4 × 109 V/m by using the local potential distribution obtained by a first-principles calculation, instead of by using the work function. As a result of the first-principles calculations of a single molecule adsorbed on a tungsten surface, we found that dissociative adsorption of a carbon monoxide (CO) molecule enhances the emission current by changing the potential barrier in the area surrounding the C and O adatoms when these two atoms are placed at their most stable positions. It is also found that the migration of the O atom from the most stable position reduces the emission current. These types of enhancement and reduction of the emission current quantitatively explain the observed quantized fluctuations of the CFE emission current.

  6. Multi-Chlorine-Substituted Self-Assembled Molecules As Anode Interlayers: Tuning Surface Properties and Humidity Stability for Organic Photovoltaics.

    Science.gov (United States)

    Cheng, Xiaofang; Huang, Liqiang; Zhang, Lifu; Ai, Qingyun; Chen, Lie; Chen, Yiwang

    2017-03-15

    Self-assembled small molecules (SASMs) are effective materials to improve the interfacial properties between a metal/metal oxide and the overlying organic layer. In this work, surface modification of indium tin oxide (ITO) electrode by a series of Cl-containing SASMs has been exploited to control the surface properties of ITO and device performance for organic photovoltaics. Depending on the position and degrees of chlorination for SASMs, we could precisely manipulate the work function of the ITO electrode, and chemisorption of SASMs on ITO as well. Consequently, a power conversion efficiency (PCE) of 9.1% was achieved with tetrachlorobenzoic acid (2,3,4,5-CBA) SASM by a simple solution-processed method based on PTB7-Th-PC 71 BM heterojunction. More intriguingly, we discover that device performance is closely associated with the humidity of ambient conditions. When the humidity increases from 35-55% to 80-95%, device performance with 2,3,4,5-CBA has negligible reduction, in contrast with other SASMs that show a sharp reduction in PCEs. The increased device performance is primarily attributed to a matched work function, stable chemisorption, and beneficial wettability with overlying active layer. These findings suggest an available approach for manufacturing inexpensive, stable, efficient, and environmentally friendly organic photovoltaics by appropriate self-assembled small molecules.

  7. Effects of water molecules on rearrangements of formamide on the kaolinite basal (001) surface.

    Science.gov (United States)

    Nguyen, Huyen Thi; Nguyen, Minh Tho

    2014-08-28

    The effects of kaolinite mineral surfaces on the unimolecular rearrangements of formamide (FM) were investigated using periodic density functional theory in conjunction with pseudopotential plane-wave approach. Surface hydroxyl groups covering the octahedral surface of kaolinite were found to play the role of catalysts in the transformations of FM. They induce a reduction of 31 kcal/mol on the energy barrier for formation of its isomer aminohydroxymethylene (AHM), which is close to the reduction amount calculated for water-catalyzed reactions. This suggests that the kaolinite octahedral surface exerts a catalytic effect similar to that of the water molecule. As the tetrahedral surface does not contain catalytic surface hydroxyl groups, only water-assisted FM transformation was therefore studied on this surface whose energy barrier amounts to ∼17 kcal/mol. The combined effect of both water and kaolinite on FM rearrangements via triple hydrogen transfer reactions does not significantly lower the energy barriers, as compared to those of double hydrogen transfer reactions. The triple hydrogen transfer energy barriers amount to ∼20 and ∼36 kcal/mol, and the double ones are ∼21 and ∼40 kcal/mol for formation of formimic acid and AHM isomers, respectively. However, the energies of the systems in water-catalyzed channels lie below the available energies of the original reactants, and thus these channels are more favored than the water-free ones. With its multiple functions as both a supporting plate-form and a catalyst for FM reactions, kaolinite can thus be regarded as an important natural catalyst for prebiotic synthesis.

  8. Ab initio investigation of the passivation effect of the acrylonitrile molecule on the Si(100)-(2 × 1) surface

    Energy Technology Data Exchange (ETDEWEB)

    Usanmaz, D., E-mail: demetusanmaz@gmail.com [Physics Program, Middle East Technical University, Northern Cyprus Campus, Kalkanlı, Güzelyurt, KKTC, Mersin 10 (Turkey); Srivastava, G.P. [School of Physics, University of Exeter, Stocker Road, Exeter EX4 4QL (United Kingdom)

    2014-08-17

    Highlights: • Different bonding configurations of acrylonitrile molecule on the Si(2 × 1) surface based on reported experimental results have been investigated. • The acrylonitrile molecule has the minimum energy configuration at the on-top adsorption site. • The adsorption of the acrylonitrile molecule passivates the Si(2 × 1) surface both chemically as well as electronically. • The resulting surface structure is passivated both chemically as well as electronically. - Abstract: Based on pseudopotentials and the density functional theory, we have investigated the atomic geometry and electronic structure of the acrylonitrile molecule adsorbed on the Si(100)-(2 × 1) surface. By considering different bonding configurations based on reported experimental results, we have investigated several possible geometries. Our total energy results suggest that the acrylonitrile molecule has the minimum energy configuration at the on-top adsorbtion site. The electronic surface properties of the most stable structure have been discussed. Our results show that the adsorption of this molecule fully passivates the Si(001)(2 × 1) surface.

  9. Inhibitors of pendrin anion exchange identified in a small molecule screen increase airway surface liquid volume in cystic fibrosis.

    Science.gov (United States)

    Haggie, Peter M; Phuan, Puay-Wah; Tan, Joseph-Anthony; Zlock, Lorna; Finkbeiner, Walter E; Verkman, A S

    2016-06-01

    Pendrin (SLC26A4) is a Cl(-)/anion exchanger expressed in the epithelium of inflamed airways where it is thought to facilitate Cl(-) absorption and HCO3 (-) secretion. Studies using pendrin knockout mice and airway epithelial cells from hearing-impaired subjects with pendrin loss of function suggest involvement of pendrin in inflammatory lung diseases, including cystic fibrosis (CF), perhaps by regulation of airway surface liquid (ASL) volume. Here we identified small-molecule pendrin inhibitors and demonstrated their efficacy in increasing ASL volume. A cell-based, functional high-throughput screen of ∼36,000 synthetic small molecules produced 3 chemical classes of inhibitors of human pendrin. After structure-activity studies, tetrahydropyrazolopyridine and pyrazolothiophenesulfonamide compounds reversibly inhibited pendrin-facilitated Cl(-) exchange with SCN(-), I(-), NO3 (-), and HCO3 (-) with drug concentration causing 50% inhibition down to ∼2.5 μM. In well-differentiated primary cultures of human airway epithelial cells from non-CF and CF subjects, treatment with IL-13, which causes inflammation with strong pendrin up-regulation, strongly increased Cl(-)/HCO3 (-) exchange and the increase was blocked by pendrin inhibition. Pendrin inhibition significantly increased ASL depth (by ∼8 μm) in IL-13-treated non-CF and CF cells but not in untreated cells. These studies implicate the involvement of pendrin-facilitated Cl(-)/HCO3 (-) in the regulation of ASL volume and suggest the utility of pendrin inhibitors in inflammatory lung diseases, including CF.-Haggie, P. M., Phuan, P.-W., Tan, J.-A., Zlock, L., Finkbeiner, W. E., Verkman, A. S. Inhibitors of pendrin anion exchange identified in a small molecule screen increase airway surface liquid volume in cystic fibrosis. © FASEB.

  10. M-ficolin, an innate immune defence molecule, binds patterns of acetyl groups and activates complement

    DEFF Research Database (Denmark)

    Frederiksen, Pernille Dorthea; Thiel, Steffen; Larsen, Claus Bindslev

    2005-01-01

    Ficolins play a role in the innate immune defence as pathogen-associated molecular pattern recognition molecules. Three ficolins are found in humans: H-ficolin, L-ficolin and M-ficolin. L-ficolin and H-ficolin circulate in blood in complexes with mannan-binding lectin-associated serine proteases...... (MASPs) and are capable of activating the complement system. L-ficolin shows affinity for acetylated compounds and binds to various capsulated strains of bacteria. H-ficolin has been shown to bind Aerococcus viridans. Less is known about M-ficolin, but it is thought to be present only on monocytes. We...... system. We developed a monoclonal rat anti-human-M/L-ficolin antibody and verified by flow cytometric analysis the presence of ficolin on the surface of peripheral blood monocytes....

  11. Decoration of carbon nano surfaces with hydrogen and hydrogen rich molecules

    International Nuclear Information System (INIS)

    Zöttl, S.

    2013-01-01

    The use of helium nano droplets as a matrix to investigate different atomic and molecular samples is a well established experimental technique. The unique properties of helium allow for different analytical methods and at the same time provide a stable ambient temperature. Cluster growth inside helium nano droplets can be accomplished by repeatedly doping the droplets with sample particles in a controlled environment. The experimental work represented in this thesis was performed using helium nano droplets to create clusters of fullerenes like C 60 and C 70 . The adsorption properties of these fullerene clusters regarding hydrogen and hydrogen rich molecules have been subject to investigation. The observed results suggest that curved carbon nano surfaces offer higher storage densities than planar graphite surfaces. The use of C 60 as a model carbon nano structure provides a well understood molecule for testing and evaluating computational methods to calculate surface properties of various carbon nano materials. The cost effective storage of hydrogen for mobile applications plays a key role in the development of alternatives to fossil fuels. For that reason, the application of carbon nano materials to store hydrogen by adsorption has attracted much scientific attention lately. The insights gained in the presented thesis contribute to the collective efforts and deliver more refined tools to estimate the adsorption properties of future carbon nano materials. In addition to the aforementioned, a time-of-flight mass spectrometer for educational purpose has been designed and constructed in the framework of my PhD thesis. The instrument is successfully used in various lab courses and information on the setup can be found in the Appendix of this work. (author) [de

  12. Biocatalytic Route to Surface Active Lipid

    DEFF Research Database (Denmark)

    Cheong, Ling-Zhi; Xu, Xuebing

    Lipid can be structurally modified in order to attain improved functional properties. This work look into the possibilities of developing surface active lipids with improved functional properties through biocatalytic route. Biocatalytic route to surface active lipid are usually complex involving ...... distinct self assembling property and find useful application in surfactant industry.......Lipid can be structurally modified in order to attain improved functional properties. This work look into the possibilities of developing surface active lipids with improved functional properties through biocatalytic route. Biocatalytic route to surface active lipid are usually complex involving...

  13. Dynamics of water molecules in the active-site cavity of human cytochromes P450

    DEFF Research Database (Denmark)

    Rydberg, Patrik; Rod, Thomas Holm; Olsen, Lars

    2007-01-01

    We have studied the dynamics of water molecules in six crystal structures of four human cytochromes P450, 2A6, 2C8, 2C9, and 3A4, with molecular dynamics simulations. In the crystal structures, only a few water molecules are seen and the reported sizes of the active-site cavity vary a lot. In the...

  14. Surface enhanced Raman optical activity (SEROA)

    DEFF Research Database (Denmark)

    Abdali, Salim; Blanch, E.W.

    2008-01-01

    Raman optical activity (ROA) directly monitors the stereochemistry of chiral molecules and is now an incisive probe of biomolecular structure. ROA spectra contain a wealth of information on tertiary folding, secondary structure and even the orientation of individual residues in proteins and nucleic...

  15. New Approaches to Measuring Sticky Molecules: Improvement of Instrumental Response Times Using Active Passivation.

    Science.gov (United States)

    Roscioli, J R; Zahniser, M S; Nelson, D D; Herndon, S C; Kolb, C E

    2016-03-10

    A novel method has been developed to improve sampling system response times for nominally "sticky" molecules such as HNO3 and NH3. The method reported here makes use of active, continuous passivation, where the instrument interfaces are continuously exposed to 0.01-1 ppm of fluorinated acidic or basic surfactants. To reduce HNO3 response times, perfluoroheptanoic acid and perfluorobutanesulfonic acid vapors are evaluated as passivation species. 1H,1H-perfluorooctylamine is used to improve NH3 response times. The resulting time responses using the perfluoroalkanoic acids are on the order of 0.4-0.7 s for a 75% quantitative recovery of HNO3, and 1-5 s for 90% recovery. Similar response time improvements are seen in detection of NH3 using perfluorooctylamine (measurements of highly polar molecules that have historically been hampered by slow response times due to adsorption on sampling system surfaces. The utility of this approach is demonstrated by field measurements of HNO3 eddy covariance fluxes in a central U.S. prairie.

  16. Effects of an electric field on the adsorption of water molecules on the Cd(0001) surface

    Science.gov (United States)

    Tu, Yu-Bing; Tao, Min-Long; Sun, Kai; Wang, Jun-Zhong

    2018-02-01

    The adsorption of water molecules on the Cd(0001) surface has been systematically investigated in the absence or presence of the electric field using first principles calculations based on density functional theory. It has been determined that the adsorption is enhanced by the electric field. From the geometries and energetics, we find that the water-cadmium interaction become stronger (weaker) under a negative (positive) field in the adsorbed monomer. Otherwise, the formation of the hydrogen bonds makes it difficult for molecules in the water clusters to response the electric field. Most importantly, the stability of the water bilayers depends on the strength of the negative electric field. Instead of the H-up bilayer, the H-down bilayer is more stable when the negative field is sufficiently strong. In this case, the dipole-field interaction is the dominant interaction in the change of stability. These results are helpful in the understanding of the fundamental processes at the water-electrode interfaces.

  17. Structure investigation of organic molecules on Au(111) surfaces; Strukturuntersuchung organischer Molekuele auf Au(111)-Oberflaechen

    Energy Technology Data Exchange (ETDEWEB)

    Kazempoor, Michel

    2009-02-02

    The present work covers two topics namely the coadsorption of formic acid and water on Au(111) and the structure of biphenylalkanthiole SAMs on Au(111) surfaces. The coadsorption of formic acid and water on Au(111) surfaces has been investigated by means of vibrational and photoelectron spectroscopy (HREELS, XPS). Formic acid adsorbs at 90 K molecularly with vibrational modes characteristic for flat lying zig-zag chains in the mono- and multilayer regime, like in solid formic acid. The structure of the flat lying formic acid chains was determined by low energy electron diffraction (LEED) as a (2r3 x r19) unit cell. Annealing results in a complete desorption at 190 K. Sequential adsorption of formic acid and water at 90 K shows no significant chemical interaction. Upon annealing the coadsorbed layer to 140 K a hydrogenbonded cyclic complex of formic acid with one water molecule could be identified using isotopically labelled adsorbates. Upon further annealing this complex decomposes leaving molecularly adsorbed formic acid on the surface at 160 K, accompanied by a proton exchange between formic acid and water. The influence of the alkane spacer chain length on the structure of biphenylalkanethiols on Au(111) surfaces was investigated as well. A systematic study was done on BPn-SAMs deposited from the gas phase. For every chain length a structure was found by LEED. Furthermore the influence of temperature on the structure was investigated in the range from room temperature up to about 400 K. To obviate influences from different preparation methods BP3 and BP4 was deposited from gas phase and from solution. No LEED spots were observed on BP4 SAMs deposited from solution. For BP3 an influence of the preparation could be excluded. For all BPn-SAMs a good agreement between LEED and STM data's was found. Nevertheless different unit cells were determined by LEED and STM consistent structures could be suggested considering the unit cell size given by LEED and the

  18. Coupling of Surface and Volume Dipole Oscillations in C60 Molecules

    Science.gov (United States)

    Brack, M.; Winkler, P.; Murthy, M. V. N.

    We first give a short review of the "local-current approximation" (LCA), derived from a general variation principle, which serves as a semiclassical description of strongly collective excitations in finite fermion systems starting from their quantum-mechanical mean-field ground state. We illustrate it for the example of coupled translational and compressional dipole excitations in metal clusters. We then discuss collective electronic dipole excitations in C60 molecules (Buckminster fullerenes). We show that the coupling of the pure translational mode ("surface plasmon") with compressional volume modes in the semiclasscial LCA yields semi-quantitative agreement with microscopic time-dependent density functional (TDLDA) calculations, while both theories yield qualitative agreement with the recent experimental observation of a "volume plasmon".

  19. Coupling of surface and volume dipole oscillations in C60 molecules

    International Nuclear Information System (INIS)

    Brack, M.; Winkler, P.; Murthy, M.V.N.

    2008-01-01

    We first give a short review of the "local-current approximation" (LCA), derived from a general variation principle, which serves as a semiclassical description of strongly collective excitations in finite fermion systems starting from their quantum-mechanical mean-field ground state. We illustrate it for the example of coupled translational and compressional dipole excitations in metal clusters. We then discuss collective electronic dipole excitations in C 60 molecules (Buckminster fullerenes). We show that the coupling of the pure translational mode ("surface plasmon") with compressional volume modes in the semiclasscial LCA yields semi-quantitative agreement with microscopic time-dependent density functional (TDLDA) calculations, while both theories yield qualitative agreement with the recent experimental observation of a "volume plasmon". (author)

  20. Stabilizing small molecules on metal oxide surfaces using atomic layer deposition.

    Science.gov (United States)

    Hanson, Kenneth; Losego, Mark D; Kalanyan, Berç; Parsons, Gregory N; Meyer, Thomas J

    2013-10-09

    Device lifetimes and commercial viability of dye-sensitized solar cells (DSSCs) and dye-sensitized photoelectrosynthesis cells (DSPECs) are dependent on the stability of the surface bound molecular chromophores and catalysts. Maintaining the integrity of the solution-metal oxide interface is especially challenging in DSPECs for water oxidation where it is necessary to perform high numbers of turnovers, under irradiation in an aqueous environment. In this study, we describe the atomic layer deposition (ALD) of TiO2 on nanocrystalline TiO2 prefunctionalized with the dye molecule [Ru(bpy)2(4,4'-(PO3H2)bpy)](2+) (RuP) as a strategy to stabilize surface bound molecules. The resulting films are over an order of magnitude more photostable than untreated films and the desorption rate constant exponentially decreases with increased thickness of ALD TiO2 overlayers. However, the injection yield for TiO2-RuP with ALD TiO2 also decreases with increasing overlayer thickness. The combination of decreased injection yield and 95% quenched emission suggests that the ALD TiO2 overlayer acts as a competitive electron acceptor from RuP*, effectively nonproductively quenching the excited state. The ALD TiO2 also increases back electron transfer rates, relative to the untreated film, but is independent of overlayer thickness. The results for TiO2-RuP with an ALD TiO2 overlayer are compared with similar films having ALD Al2O3 overlayers.

  1. PREFACE: International Conference on Many Particle Spectroscopy of Atoms, Molecules, Clusters and Surfaces (MPS2014)

    Science.gov (United States)

    Ancarani, Lorenzo Ugo

    2015-04-01

    This volume contains a collection of contributions from the invited speakers at the 2014 edition of the International Conference on Many Particle Spectroscopy of Atoms, Molecules, Clusters and Surfaces held in Metz, France, from 15th to 18th July 2014. This biennial conference alternates with the ICPEAC satellite International Symposium on (e,2e), Double Photoionization and Related Topics, and is concerned with experimental and theoretical studies of radiation interactions with matter. These include many-body and electron-electron correlation effects in excitation, and in single and multiple ionization of atoms, molecules, clusters and surfaces with various projectiles: electrons, photons and ions. More than 80 scientists, from 19 different countries around the world, came together to discuss the most recent progress on these topics. The scientific programme included 28 invited talks and a poster session extending over the three days of the meeting. Amongst the 51 posters, 11 have been selected and were advertised through short talks. Besides, Professor Nora Berrah gave a talk in memory of Professor Uwe Becker who sadly passed away shortly after co-chairing the previous edition of this conference. Financial support from the Institut Jean Barriol, Laboratoire SRSMC, Groupement de Recherche THEMS (CNRS), Ville de Metz, Metz Métropole, Conseil Général de la Moselle and Région Lorraine is gratefully acknowledged. Finally, I would like to thank the members of the local committee and the staff of the Université de Lorraine for making the conference run smoothly, the International Advisory Board for building up the scientific programme, the sessions chairpersons, those who gave their valuable time in carefully refereeing the articles of this volume and last, but not least, all participants for contributing to lively and fruitful discussions throughout the meeting.

  2. Structure-Activity Relation of AMOR Sugar Molecule That Activates Pollen-Tubes for Ovular Guidance.

    Science.gov (United States)

    Jiao, Jiao; Mizukami, Akane G; Sankaranarayanan, Subramanian; Yamguchi, Junichiro; Itami, Kenichiro; Higashiyawma, Tetsuya

    2017-01-01

    Successful fertilization in flowering plants depends on the precise directional growth control of pollen tube through the female pistil tissue toward the female gametophyte contained in the ovule for delivery of nonmotile sperm cells. Cys-rich peptides LUREs secreted from the synergid cells on either side of the egg cell act as ovular attractants of pollen tubes. Competency control by the pistil is crucial for the response of pollen tubes to these ovular attractants. We recently reported that ovular 4-O-methyl-glucuronosyl arabinogalactan (AMOR) induces competency of the pollen tube to respond to ovular attractant LURE peptides in Torenia fournieri. The beta isomer of the terminal disaccharide 4-O-methyl-glucuronosyl galactose was essential and sufficient for the competency induction. However, critical and noncritical structures in the disaccharide have not been dissected deeply. Herein, we report the synthesis of new AMOR analogs and the structure-activity relationships for AMOR activity in the presence of these synthesized analogs. Removal of 4-O-methyl group or -COOH from the glucuronosyl residue of the disaccharide dramatically reduces AMOR activity. The pyranose backbone of the second sugar of disaccharide is essential for the activity but not hydroxy groups. The role of beta isomer of the disaccharide 4-Me-GlcA-β(1,6)-Gal is very specific for competency control, as there was no difference in effect among the sugar analogs tested for pollen germination. This study represents the first structure-activity relationship study, to our knowledge, of a sugar molecule involved in plant reproduction, which opens a way for modification of the molecule without loss of activity. © 2017 American Society of Plant Biologists. All Rights Reserved.

  3. Adhesion molecules levels in blood correlate with MRI activity and clinical activity in multiple sclerosis

    International Nuclear Information System (INIS)

    Millers, A.; Enina, G.; Platkajis, A.; Metra, M.; Kukaine, R.

    2002-01-01

    Research into pathogenesis of multiple sclerosis (MS) has prompted efforts to identify immunological markers associated with disease activity. Adhesion molecules ICAM-1 and VCAM-1 are associated with inflammatory mediated blood-brain barrier (BBB) dysfunction. In this study investigates the correlation between blood level of circulating ICAM-1 and VCAM-1 and magnetic resonance imaging (MRI) activity in different clinical phases of patients with MS. We show that RRMS and SPMS patients in clinically active phase with Gd-enhancing lesions in CNS had higher blood levels of cICAM-1 and cVCAM-1 compared these parameters levers of RRMS patients in remission stage. These results suggest that cICAM-1 and cVCAM-1 is a sensitive indicator of disease activity associated with BBB inflammatory dysfunction. Elevated blood level of cICAM-1 more strongly correlated with clinical activity and BBB damage, than cVCAM-1 and that could be used as biological marker of disease activity. Circulating VCAM-1 as an early indicator of BBB disturbance, may also serve as marker of beneficial activity in relapses phase of MS course. (authors)

  4. Quantum dynamics of STM and laser induced desorption of atoms and molecules from surfaces

    CERN Document Server

    Boendgen, G

    2001-01-01

    The manipulation of atoms and molecules at solid surfaces by electronic excitations with electrons (or holes) emitted from the tip of a scanning tunneling microscope (STM) or with laser radiation is both of applied and fundamental interest, e.g. for micro- and nanostructuring of materials, the clarification of elementary (catalytic) reaction mechanisms and for the question of how to treat the quantum dynamics of a laser or STM driven 'system' (the adsorbate) in contact with a dissipative (energy-withdrawing) 'bath' (the substrate). Desorption induced by electronic transitions (DIET) and its variant DIMET (M = multiple) are among the simplest possible 'reactions' of adsorbate-surface systems; usually involving extremely short-lived electronically excited intermediates. In this thesis, the ultra-short dynamics of directly (localised to the adsorbate-substrate complex) and indirectly (i.e., through the substrate) stimulated DIET and DIMET processes was studied for Si(100)-(2x1):H(D) and Pt(111):NO. Isotope effec...

  5. Features of the electronic structure of the active center of an HbS molecule

    Science.gov (United States)

    Novoselov, D. Yu.; Korotin, Dm. M.; Anisimov, V. I.

    2016-01-01

    Features of the electronic structure of the nonprotein part of the mutant form of the human hemoglobin molecule, HbS, are studied along with the magnetic state of the iron ion that is the "nucleus" of the active center of the molecule. It is found that the mutant form of the HbS molecule differs from a normal hemoglobin molecule by the distortion of the local environment of the iron ion, which changes the energy level splitting by a crystal field. As a result of ab initio calculations, the magnetic transition in the iron atom from the high-spin state to the low-spin state upon the addition of molecular oxygen to hemoglobin molecule is reproduced. It is established for the first time that a change in the crystal and electronic structure of the active center as a result of a mutation can lead to a substantial change in the energy of the bond between the active center of the hemoglobin molecule and an oxygen molecule.

  6. The neuroplastin adhesion molecules are accessory proteins that chaperone the monocarboxylate transporter MCT2 to the neuronal cell surface.

    Directory of Open Access Journals (Sweden)

    Marieangela C Wilson

    Full Text Available The neuroplastins np65 and np55 are two synapse-enriched immunoglobulin (Ig superfamily adhesion molecules that contain 3 and 2 Ig domains respectively. Np65 is implicated in long term, activity dependent synaptic plasticity, including LTP. Np65 regulates the surface expression of GluR1 receptor subunits and the localisation of GABA(A receptor subtypes in hippocampal neurones. The brain is dependent not only on glucose but on monocarboxylates as sources of energy. The. monocarboxylate transporters (MCTs 1-4 are responsible for the rapid proton-linked translocation of monocarboxylates including pyruvate and lactate across the plasma membrane and require association with either embigin or basigin, proteins closely related to neuroplastin, for plasma membrane expression and activity. MCT2 plays a key role in providing lactate as an energy source to neurons.Here we use co-transfection of neuroplastins and monocarboxylate transporters into COS-7 cells to demonstrate that neuroplastins can act as ancillary proteins for MCT2. We also show that Xenopus laevis oocytes contain endogenous neuroplastin and its knockdown with antisense RNA reduces the surface expression of MCT2 and associated lactate transport. Immunocytochemical studies show that MCT2 and the neuroplastins are co-localised in rat cerebellum. Strikingly neuroplastin and MCT2 are enriched in the same parasagittal zebrin II-negative stripes.These data strongly suggest that neuroplastins act as key ancillary proteins for MCT2 cell surface localisation and activity in some neuronal populations, thus playing an important role in facilitating the uptake of lactate for use as a respiratory fuel.

  7. Control of magnetism in dilute magnetic semiconductor (Ga,MnAs films by surface decoration of molecules

    Directory of Open Access Journals (Sweden)

    Hailong eWang

    2016-03-01

    Full Text Available The responses of magnetic moments to external stimuli such as magnetic-field, heat, light and electric-field have been utilized to manipulate the magnetism in magnetic semiconductors, with many of the novel ideas applied even to ferromagnetic metals. Here, we review a new experimental development on the control of magnetism in (Ga,MnAs thin films by surface decoration of organic molecules: Molecules deposited on the surface of (Ga,MnAs thin films are shown to be capable of significantly modulating their saturation magnetization and Curie temperature. These phenomena are shown to originate from the carrier-mediated ferromagnetism in (Ga,MnAs and the surface molecules acting as acceptors or donors depending on their highest occupied molecular orbitals, resembling the charge transfer mechanism in a pn junction in which the equilibrium state is reached on the alignment of Fermi levels.

  8. Function of adhesion molecules lymphocyte function-associated antigen-3 and intercellular adhesion molecule-1 on human epidermal Langerhans cells in antigen-specific T cell activation

    NARCIS (Netherlands)

    Teunissen, M. B.; Rongen, H. A.; Bos, J. D.

    1994-01-01

    In addition to the interaction between the TCR and the MHC/Ag complex on the APC, optimal T cell activation also requires interaction between adhesion molecules on the APC and their ligands on T cells. We determined the presence of adhesion molecules on human epidermal Langerhans cells (LC) and

  9. Full-potential self-consistent linearized-augmented-plane-wave method for calculating the electronic structure of molecules and surfaces: O2 molecule

    International Nuclear Information System (INIS)

    Wimmer, E.; Krakauer, H.; Weinert, M.; Freeman, A.J.

    1981-01-01

    The linearized-augmented-plane-wave (LAPW) method for thin films is generalized by removing the remaining shape approximation to the potential inside the atomic spheres. A new technique for solving Poisson's equation for a general charge density and potential is described and implemented in the film LAPW method. In the resulting full-potential LAPW method (FLAPW), all contributions to the potential are completely taken into account in the Hamiltonian matrix elements. The accuracy of the method: already well known for clean metal surfaces: is demonstrated for the case of a nearly free (noninteracting) O 2 molecule which is a severe test case of the method because of its large anisotropic charge distribution. Detailed comparisons show that the accuracy of the FLAPW results for O 2 exceeds that of existing state-of-the-art local-density linear-combination-of-atomic-orbitals (LCAO)-type calculations, and that taking the full potential LAPW results as a reference, the LCAO basis can be improved by adding off-site functions. Thus the full-potential LAPW is a unified method which is ideally suited to test not only molecular adsorption on surfaces, but also the components of the same system separately, i.e., the extreme limits of the molecule and the clean surface

  10. Investigating organic molecules responsible of auxin-like activity of humic acid fraction extracted from vermicompost

    International Nuclear Information System (INIS)

    Scaglia, Barbara; Nunes, Ramom Rachide; Rezende, Maria Olímpia Oliveira; Tambone, Fulvia; Adani, Fabrizio

    2016-01-01

    This work studied the auxin-like activity of humic acids (HA) obtained from vermicomposts produced using leather wastes plus cattle dung at different maturation stages (fresh, stable and mature). Bioassays were performed by testing HA concentrations in the range of 100–6000 mg carbon L −1 . 13 C CPMAS-NMR and GC–MS instrumental methods were used to assess the effect of biological processes and starting organic mixtures on HA composition. Not all HAs showed IAA-like activity and in general, IAA-like activity increased with the length of the vermicomposting process. The presence of leather wastes was not necessary to produce the auxin-like activity of HA, since HA extracted from a mix of cattle manure and sawdust, where no leather waste was added, showed IAA-like activity as well. CPMAS 13 CNMR revealed that HAs were similar independently of the mix used and that the humification process involved the increasing concentration of pre-existing alkali soluble fractions in the biomass. GC/MS allowed the identification of the molecules involved in IAA-like effects: carboxylic acids and amino acids. The concentration of active molecules, rather than their simple presence in HA, determined the bio-stimulating effect, and a good linear regression between auxin-like activity and active stimulating molecules concentration was found (R 2 = − 0.85; p < 0.01, n = 6). - Highlights: • Vermicomposting converts waste into organic fertilizer. • Vermicomposts can have biostimulating effect for the presence of hormone-like molecules. • Auxine-like activity was associated to the vermicompost humic acid fraction (HA). • HA carboxylic acids and amino acids, were reported to act as auxin-like molecules. • A linear regression was found between molecules and auxin-like activity.

  11. Investigating organic molecules responsible of auxin-like activity of humic acid fraction extracted from vermicompost

    Energy Technology Data Exchange (ETDEWEB)

    Scaglia, Barbara, E-mail: barbara.scaglia@unimi.it [Gruppo Ricicla Labs – DiSAA, Università degli Studi di Milano, Via Celoria 2 (Italy); Nunes, Ramom Rachide; Rezende, Maria Olímpia Oliveira [Laboratório de Química Ambiental, Universidade de São Paulo, Instituto de Química de São Carlos, Avenida Trabalhador São Carlense, 400, São Carlos (Brazil); Tambone, Fulvia [Gruppo Ricicla Labs – DiSAA, Università degli Studi di Milano, Via Celoria 2 (Italy); Adani, Fabrizio, E-mail: fabrizio.adani@unimi.it [Gruppo Ricicla Labs – DiSAA, Università degli Studi di Milano, Via Celoria 2 (Italy)

    2016-08-15

    This work studied the auxin-like activity of humic acids (HA) obtained from vermicomposts produced using leather wastes plus cattle dung at different maturation stages (fresh, stable and mature). Bioassays were performed by testing HA concentrations in the range of 100–6000 mg carbon L{sup −1}. {sup 13}C CPMAS-NMR and GC–MS instrumental methods were used to assess the effect of biological processes and starting organic mixtures on HA composition. Not all HAs showed IAA-like activity and in general, IAA-like activity increased with the length of the vermicomposting process. The presence of leather wastes was not necessary to produce the auxin-like activity of HA, since HA extracted from a mix of cattle manure and sawdust, where no leather waste was added, showed IAA-like activity as well. CPMAS {sup 13}CNMR revealed that HAs were similar independently of the mix used and that the humification process involved the increasing concentration of pre-existing alkali soluble fractions in the biomass. GC/MS allowed the identification of the molecules involved in IAA-like effects: carboxylic acids and amino acids. The concentration of active molecules, rather than their simple presence in HA, determined the bio-stimulating effect, and a good linear regression between auxin-like activity and active stimulating molecules concentration was found (R{sup 2} = − 0.85; p < 0.01, n = 6). - Highlights: • Vermicomposting converts waste into organic fertilizer. • Vermicomposts can have biostimulating effect for the presence of hormone-like molecules. • Auxine-like activity was associated to the vermicompost humic acid fraction (HA). • HA carboxylic acids and amino acids, were reported to act as auxin-like molecules. • A linear regression was found between molecules and auxin-like activity.

  12. Expression of adhesion and activation molecules on lymphocytes during open-heart surgery with cardiopulmonary bypass

    DEFF Research Database (Denmark)

    Toft, P; Tønnesen, Else Kirstine; Zülow, I

    1997-01-01

    -heart surgery and eight with abdominal surgery were studied. The adhesion molecules CD11a/CD18 (LFA-1_, CD11c/CD18 and CD44 and the activation molecules CD25, CD69, CD71 and MHCII were measured, using monoclonal antibodies and flow cytometry. Lymphocytopenia was observed during CPB and for some hours after both...... open-heart and abdominal surgery. The proportion of CD11a/CD18-positive lymphocytes rose from 67.6 +/- 8% to 86.4 +/- 3% after aortic declamping (p ... was associated with increased expression of the adhesion molecule CD11a/CD18 on lymphocytes, while the expression of activation molecules on lymphocytes was unchanged....

  13. Immobilization of Active Bacteriophages on Polyhydroxyalkanoate Surfaces.

    Science.gov (United States)

    Wang, Chanchan; Sauvageau, Dominic; Elias, Anastasia

    2016-01-20

    A rapid, efficient technique for the attachment of bacteriophages (phages) onto polyhydroxyalkanoate (PHA) surfaces has been developed and compared to three reported methods for phage immobilization. Polymer surfaces were modified to facilitate phage attachment using (1) plasma treatment alone, (2) plasma treatment followed by activation by 1-ethyl-3-(3-(dimethylamino)propyl)carbodiimide hydrochloride (EDC) and N-hydroxysulfosuccinimide (sulfo-NHS), (3) plasma-initiated acrylic acid grafting, or (4) plasma-initiated acrylic acid grafting with activation by EDC and sulfo-NHS. The impact of each method on the surface chemistry of PHA was investigated using contact angle analysis and X-ray photoelectron spectroscopy. Each of the four treatments was shown to result in both increased hydrophilicity and in the modification of the surface functional groups. Modified surfaces were immersed in suspensions of phage T4 for immobilization. The highest level of phage binding was observed for the surfaces modified by plasma treatment alone. The change in chemical bond states observed for surfaces that underwent plasma treatment is suspected to be the cause of the increased binding of active phages. Plasma-treated surfaces were further analyzed through phage-staining and fluorescence microscopy to assess the surface density of immobilized phages and their capacity to capture hosts. The infective capability of attached phages was confirmed by exposing the phage-immobilized surfaces to the host bacteria Escherichia coli in both plaque and infection dynamic assays. Plasma-treated surfaces with immobilized phages displayed higher infectivity than surfaces treated with other methods; in fact, the equivalent initial multiplicity of infection was 2 orders of magnitude greater than with other methods. Control samples - prepared by immersing polymer surfaces in phage suspensions (without prior plasma treatment) - did not show any bacterial growth inhibition, suggesting they did not bind

  14. Calculation and fitting of potential energy and dipole moment surfaces for the water molecule: Fully ab initio determination of vibrational transition energies and band intensities

    International Nuclear Information System (INIS)

    Kedziora, G.S.; Shavitt, I.

    1997-01-01

    Potential energy and dipole moment surfaces for the water molecule have been generated by multireference singles-and-doubles configuration interaction calculations using a large basis set of the averaged-atomic-natural-orbital type and a six-orbital-six-electron complete-active-space reference space. The surfaces are suitable for modeling vibrational transitions up to about 11000cm -1 above the ground state. A truncated singular-value decomposition method has been used to fit the surfaces. This fitting method is numerically stable and is a useful tool for examining the effectiveness of various fitting function forms in reproducing the calculated surface points and in extrapolating beyond these points. The fitted surfaces have been used for variational calculations of the 30 lowest band origins and the corresponding band intensities for transitions from the ground vibrational state. With a few exceptions, the results compare well with other calculations and with experimental data. copyright 1997 American Institute of Physics

  15. Cell recognition molecule L1 promotes embryonic stem cell differentiation through the regulation of cell surface glycosylation

    Energy Technology Data Exchange (ETDEWEB)

    Li, Ying [Department of Biochemistry and Molecular Biology, Dalian Medical University, Dalian 116044 (China); Department of Clinical Laboratory, Second Affiliated Hospital of Dalian Medical University, Dalian 116023 (China); Huang, Xiaohua [Department of Biochemistry and Molecular Biology, Dalian Medical University, Dalian 116044 (China); Department of Clinical Biochemistry, College of Laboratory Medicine, Dalian Medical University, Dalian 116044 (China); An, Yue [Department of Clinical Laboratory, Second Affiliated Hospital of Dalian Medical University, Dalian 116023 (China); Ren, Feng [Department of Biochemistry and Molecular Biology, Dalian Medical University, Dalian 116044 (China); Yang, Zara Zhuyun; Zhu, Hongmei; Zhou, Lei [The Key Laboratory of Stem Cell and Regenerative Medicine, Institute of Molecular and Clinical Medicine, Kunming Medical University, Kunming 650228 (China); Department of Anatomy and Developmental Biology, Monash University, Clayton 3800 (Australia); He, Xiaowen; Schachner, Melitta [Keck Center for Collaborative Neuroscience and Department of Cell Biology and Neuroscience, Rutgers University, New Brunswick, NJ (United States); Xiao, Zhicheng, E-mail: zhicheng.xiao@monash.edu [The Key Laboratory of Stem Cell and Regenerative Medicine, Institute of Molecular and Clinical Medicine, Kunming Medical University, Kunming 650228 (China); Department of Anatomy and Developmental Biology, Monash University, Clayton 3800 (Australia); Ma, Keli, E-mail: makeli666@aliyun.com [Department of Biochemistry and Molecular Biology, Dalian Medical University, Dalian 116044 (China); Li, Yali, E-mail: yalilipaper@gmail.com [Department of Biochemistry and Molecular Biology, Dalian Medical University, Dalian 116044 (China); Department of Anatomy, National University of Singapore, Singapore 119078 (Singapore)

    2013-10-25

    Highlights: •Down-regulating FUT9 and ST3Gal4 expression blocks L1-induced neuronal differentiation of ESCs. •Up-regulating FUT9 and ST3Gal4 expression in L1-ESCs depends on the activation of PLCγ. •L1 promotes ESCs to differentiate into neuron through regulating cell surface glycosylation. -- Abstract: Cell recognition molecule L1 (CD171) plays an important role in neuronal survival, migration, differentiation, neurite outgrowth, myelination, synaptic plasticity and regeneration after injury. Our previous study has demonstrated that overexpressing L1 enhances cell survival and proliferation of mouse embryonic stem cells (ESCs) through promoting the expression of FUT9 and ST3Gal4, which upregulates cell surface sialylation and fucosylation. In the present study, we examined whether sialylation and fucosylation are involved in ESC differentiation through L1 signaling. RNA interference analysis showed that L1 enhanced differentiation of ESCs into neurons through the upregulation of FUT9 and ST3Gal4. Furthermore, blocking the phospholipase Cγ (PLCγ) signaling pathway with either a specific PLCγ inhibitor or knockdown PLCγ reduced the expression levels of both FUT9 and ST3Gal4 mRNAs and inhibited L1-mediated neuronal differentiation. These results demonstrate that L1 promotes neuronal differentiation from ESCs through the L1-mediated enhancement of FUT9 and ST3Gal4 expression.

  16. Cell recognition molecule L1 promotes embryonic stem cell differentiation through the regulation of cell surface glycosylation

    International Nuclear Information System (INIS)

    Li, Ying; Huang, Xiaohua; An, Yue; Ren, Feng; Yang, Zara Zhuyun; Zhu, Hongmei; Zhou, Lei; He, Xiaowen; Schachner, Melitta; Xiao, Zhicheng; Ma, Keli; Li, Yali

    2013-01-01

    Highlights: •Down-regulating FUT9 and ST3Gal4 expression blocks L1-induced neuronal differentiation of ESCs. •Up-regulating FUT9 and ST3Gal4 expression in L1-ESCs depends on the activation of PLCγ. •L1 promotes ESCs to differentiate into neuron through regulating cell surface glycosylation. -- Abstract: Cell recognition molecule L1 (CD171) plays an important role in neuronal survival, migration, differentiation, neurite outgrowth, myelination, synaptic plasticity and regeneration after injury. Our previous study has demonstrated that overexpressing L1 enhances cell survival and proliferation of mouse embryonic stem cells (ESCs) through promoting the expression of FUT9 and ST3Gal4, which upregulates cell surface sialylation and fucosylation. In the present study, we examined whether sialylation and fucosylation are involved in ESC differentiation through L1 signaling. RNA interference analysis showed that L1 enhanced differentiation of ESCs into neurons through the upregulation of FUT9 and ST3Gal4. Furthermore, blocking the phospholipase Cγ (PLCγ) signaling pathway with either a specific PLCγ inhibitor or knockdown PLCγ reduced the expression levels of both FUT9 and ST3Gal4 mRNAs and inhibited L1-mediated neuronal differentiation. These results demonstrate that L1 promotes neuronal differentiation from ESCs through the L1-mediated enhancement of FUT9 and ST3Gal4 expression

  17. Study of the Adsorption of Atoms and Molecules on Silicon Surfaces Crystallographics and Electronic Structure

    CERN Document Server

    Bengio, S

    2003-01-01

    This thesis work has been concerned with adsorption properties of silicon surfaces.The atomic and electronic structure of molecules and atoms adsorbed on Si has been investigated by means of photoemission experiments combined with synchrotron radiation.The quantitative atomic structure determination was held applying the photoelectron diffraction technique.This technique is sensible to the local structure of a reference atomic specie and has elemental and chemical-state specificity.This approach has been applied to three quite different systems with different degrees of complexity, Sb/Si(111) sq root 3x sq root 3R30 sup 0 , H sub 2 O/Si(100)2x1 and NH sub 3 /Si(111)7x7.Our results show that Sb which forms a ( sq root 3 sq root 3)R30 sup 0 phase produces a bulklike-terminated Si(111)1x1 substrate free of stacking faults.Regarding the atomic structure of its interface, this study strongly favours the T4-site milkstool model over the H3 one.An important aspect regarding the H sub 2 O/Si(100)(2x1) system was esta...

  18. Ozone kinetics in low-pressure discharges: vibrationally excited ozone and molecule formation on surfaces

    International Nuclear Information System (INIS)

    Marinov, Daniil; Guaitella, Olivier; Booth, Jean-Paul; Rousseau, Antoine; Guerra, Vasco

    2013-01-01

    A combined experimental and modeling investigation of the ozone kinetics in the afterglow of pulsed direct current discharges in oxygen is carried out. The discharge is generated in a cylindrical silica tube of radius 1 cm, with short pulse durations between 0.5 and 2 ms, pressures in the range 1–5 Torr and discharge currents ∼40–120 mA. Time-resolved absolute concentrations of ground-state atoms and ozone molecules were measured simultaneously in situ, by two-photon absorption laser-induced fluorescence and ultraviolet absorption, respectively. The experiments were complemented by a self-consistent model developed to interpret the results and, in particular, to evaluate the roles of vibrationally excited ozone and of ozone formation on surfaces. It is found that vibrationally excited ozone, O 3 * , plays an important role in the ozone kinetics, leading to a decrease in the ozone concentration and an increase in its formation time. In turn, the kinetics of O 3 * is strongly coupled with those of atomic oxygen and O 2 (a 1 Δ g ) metastables. Ozone formation at the wall does not contribute significantly to the total ozone production under the present conditions. Upper limits for the effective heterogeneous recombination probability of O atoms into ozone are established. (paper)

  19. Ozone kinetics in low-pressure discharges: vibrationally excited ozone and molecule formation on surfaces

    Science.gov (United States)

    Marinov, Daniil; Guerra, Vasco; Guaitella, Olivier; Booth, Jean-Paul; Rousseau, Antoine

    2013-10-01

    A combined experimental and modeling investigation of the ozone kinetics in the afterglow of pulsed direct current discharges in oxygen is carried out. The discharge is generated in a cylindrical silica tube of radius 1 cm, with short pulse durations between 0.5 and 2 ms, pressures in the range 1-5 Torr and discharge currents ˜40-120 mA. Time-resolved absolute concentrations of ground-state atoms and ozone molecules were measured simultaneously in situ, by two-photon absorption laser-induced fluorescence and ultraviolet absorption, respectively. The experiments were complemented by a self-consistent model developed to interpret the results and, in particular, to evaluate the roles of vibrationally excited ozone and of ozone formation on surfaces. It is found that vibrationally excited ozone, O_3^{*} , plays an important role in the ozone kinetics, leading to a decrease in the ozone concentration and an increase in its formation time. In turn, the kinetics of O_3^{*} is strongly coupled with those of atomic oxygen and O2(a 1Δg) metastables. Ozone formation at the wall does not contribute significantly to the total ozone production under the present conditions. Upper limits for the effective heterogeneous recombination probability of O atoms into ozone are established.

  20. Electronic coupling effects and charge transfer between organic molecules and metal surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Forker, Roman

    2010-07-01

    We employ a variant of optical absorption spectroscopy, namely in situ differential reflectance spectroscopy (DRS), for an analysis of the structure-properties relations of thin epitaxial organic films. Clear correlations between the spectra and the differently intense coupling to the respective substrates are found. While rather broad and almost structureless spectra are obtained for a quaterrylene (QT) monolayer on Au(111), the spectral shape resembles that of isolated molecules when QT is grown on graphite. We even achieve an efficient electronic decoupling from the subjacent Au(111) by inserting an atomically thin organic spacer layer consisting of hexa-peri-hexabenzocoronene (HBC) with a noticeably dissimilar electronic behavior. These observations are further consolidated by a systematic variation of the metal substrate (Au, Ag, and Al), ranging from inert to rather reactive. For this purpose, 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) is chosen to ensure comparability of the molecular film structures on the different metals, and also because its electronic alignment on various metal surfaces has previously been studied with great intensity. We present evidence for ionized PTCDA at several interfaces and propose the charge transfer to be related to the electronic level alignment governed by interface dipole formation on the respective metals. (orig.)

  1. Flow cytometric investigation of immune-response-related surface molecules on human colorectal cancers

    DEFF Research Database (Denmark)

    Diederichsen, Axel Cosmus Pyndt; Stenholm, A C; Kronborg, O

    1998-01-01

    different colorectal cancers were monitored by multiparameter flow cytometry. Gating on EP4+ cells, the expression of the surface molecules HLA class I, HLA class II, CD80 (B7-1), CD54 (ICAM-I) and CD58 (LFA-3) was evaluated. In 60 of 70 tumours, all tumour cells expressed HLA class I, in 10 tumours 15......Our purpose was to clarify whether human colorectal cancer cells are equipped to present tumour-associated-antigens to the immune system, and whether this ability correlates with lymphoid infiltration, the Dukes' stage and Jass classification. Enzymatically dissociated tumour cells from 70......-96% of the tumour cells expressed HLA class I. In 1 tumour, all tumour cells expressed HLA class II, in 67 tumours some expressed HLA class II, in 2 tumours none expressed HLA class II. Expression of CD58 was heterogeneous, and there was no or only sparse expression of CD80 and CD54. Expression of the HLA class I...

  2. Monocyte and lymphocyte surface molecules in severe sepsis and non-septic critically ill Patients.

    Science.gov (United States)

    Jämsä, Joel; Syrjälä, Hannu; Huotari, Virva; Savolainen, Eeva-Riitta; Ala-Kokko, Tero

    2017-06-01

    The aim of the present study was to investigate whether expression of monocyte and lymphocyte surface molecules differs between patients with severe sepsis and non-septic patients treated in the intensive care unit (ICU). The expression of monocyte CD14, CD40, CD80 and HLA-DR, and lymphocyte CD69 were analyzed using quantitative flow cytometry on three consecutive days in 27 patients with severe sepsis and in 15 non-septic patients. Receiver operating characteristic analyses were performed and each corresponding area under the curve (AUC) was determined. The results showed that the expression levels of CD40 on monocytes and CD69 on CD4+ T cells and on natural killer (NK) cells were highest in patients with severe sepsis (p sepsis and positive blood culture compared with those with negative blood culture (p sepsis detection were 0.836 for CD40, 0.872 for CD69 on NK cells, and 0.795 for CD69 on CD4+ T cells. These findings suggest that monocyte CD40 and CD69 on NK cells and CD4+ T cells could prove useful for new approaches in the identification of severe sepsis in the ICU. © 2017 APMIS. Published by John Wiley & Sons Ltd.

  3. Water molecule network and active site flexibility of apo protein tyrosine phosphatase 1B

    DEFF Research Database (Denmark)

    Pedersen, A.K.; Peters, Günther H.J.; Møller, K.B.

    2004-01-01

    the conformation and flexibility of active-site residues as well as the water-molecule network, is a key issue in understanding ligand binding and enzyme kinetics and in structure-based drug design. A 1.95 Angstrom apo PTP1B structure has been obtained, showing four highly coordinated water molecules in the active......Protein tyrosine phosphatase 1B (PTP1B) plays a key role as a negative regulator of insulin and leptin signalling and is therefore considered to be an important molecular target for the treatment of type 2 diabetes and obesity. Detailed structural information about the structure of PTP1B, including......-site pocket of the enzyme; hence, the active site is highly solvated in the apo state. Three of the water molecules are located at positions that approximately correspond to the positions of the phosphate O atoms of the natural substrate phosphotyrosine and form a similar network of hydrogen bonds. The active...

  4. Small molecule SIRT1 activators for the treatment of aging and age-related diseases.

    Science.gov (United States)

    Hubbard, Basil P; Sinclair, David A

    2014-03-01

    Recent studies in mice have identified single molecules that can delay multiple diseases of aging and extend lifespan. In theory, such molecules could prevent dozens of diseases simultaneously, potentially extending healthy years of life. In this review, we discuss recent advances, controversies, opportunities, and challenges surrounding the development of SIRT1 activators, molecules with the potential to delay aging and age-related diseases. Sirtuins comprise a family of NAD⁺-dependent deacylases that are central to the body's response to diet and exercise. New studies indicate that both natural and synthetic sirtuin activating compounds (STACs) work via a common allosteric mechanism to stimulate sirtuin activity, thereby conferring broad health benefits in rodents, primates, and possibly humans. The fact that two-thirds of people in the USA who consume multiple dietary supplements consume resveratrol, a SIRT1 activator, underscores the importance of understanding the biochemical mechanism, physiological effects, and safety of STACs. Copyright © 2013 Elsevier Ltd. All rights reserved.

  5. High-risk human papillomavirus E7 expression reduces cell-surface MHC class I molecules and increases susceptibility to natural killer cells

    DEFF Research Database (Denmark)

    Bottley, G; Watherston, O G; Hiew, Y-L

    2007-01-01

    a role for E7 in tumour immune evasion. We show that knockdown of E7 expression in HPV16- and HPV18-transformed cervical carcinoma cells by RNA interference increased expression of major histocompatibility complex (MHC) class I at the cell surface and reduced susceptibility of these cells to natural...... killer (NK) cells. Tetracycline-regulated induction of HPV16 E7 resulted in reduced expression of cell surface MHC class I molecules and increased NK cell killing. Our results suggest that, for HPV-associated malignancies, reduced MHC class I expression is the result of an active immune evasion strategy...

  6. Possibility of 1-nm level localization of a single molecule with gap-mode surface-enhanced Raman scattering

    International Nuclear Information System (INIS)

    Choi, Han Kyu; Kim, Zee Hwan

    2015-01-01

    The electromagnetic (EM) enhancement mechanism of surface-enhanced Raman scattering (SERS) has been well established through 30 years of extensive investigation: molecules adsorbed on resonantly driven silver or gold nanoparticles (NPs) experience strongly enhanced field and thus show enhanced Raman scattering. Even stronger SERS enhancement is possible with a gap structure in which two or more NPs form assemblies with gap sizes of 1 nm or less. We have theoretically shown that the measurement of SERS angular distribution can reveal the position of a single molecule near the gap with 1-nm accuracy, even though the spatial extent of the enhanced field is ~10 nm. Real implementation of such experiment requires extremely well-defined (preferably a single crystal) dimeric junctions. Nevertheless, the experiment will provide spatial as well as frequency domain information on single-molecule dynamics at metallic surfaces

  7. The fungal quorum-sensing molecule farnesol activates innate immune cells but suppresses cellular adaptive immunity.

    Science.gov (United States)

    Leonhardt, Ines; Spielberg, Steffi; Weber, Michael; Albrecht-Eckardt, Daniela; Bläss, Markus; Claus, Ralf; Barz, Dagmar; Scherlach, Kirstin; Hertweck, Christian; Löffler, Jürgen; Hünniger, Kerstin; Kurzai, Oliver

    2015-03-17

    important for fungal clearance and protective immunity. We show that farnesol is able to enhance inflammation by inducing activation of neutrophils and monocytes. At the same time, farnesol impairs differentiation of monocytes into immature dendritic cells (iDC) by modulating surface phenotype, cytokine release and migrational behavior. Consequently, iDC generated in the presence of farnesol are unable to induce proper T cell responses and fail to secrete Th1 promoting interleukin 12 (IL-12). As farnesol induced down-regulation of the granulocyte-macrophage colony-stimulating factor (GM-CSF) receptor, desensitization to GM-CSF could potentially explain transcriptional reprofiling of iDC effector molecules. Taken together, our data show that farnesol can also mediate Candida-host communication and is able to act as a virulence factor. Copyright © 2015 Leonhardt et al.

  8. Exploring sets of molecules from patents and relationships to other active compounds in chemical space networks

    Science.gov (United States)

    Kunimoto, Ryo; Bajorath, Jürgen

    2017-09-01

    Patents from medicinal chemistry represent a rich source of novel compounds and activity data that appear only infrequently in the scientific literature. Moreover, patent information provides a primary focal point for drug discovery. Accordingly, text mining and image extraction approaches have become hot topics in patent analysis and repositories of patent data are being established. In this work, we have generated network representations using alternative similarity measures to systematically compare molecules from patents with other bioactive compounds, visualize similarity relationships, explore the chemical neighbourhood of patent molecules, and identify closely related compounds with different activities. The design of network representations that combine patent molecules and other bioactive compounds and view patent information in the context of current bioactive chemical space aids in the analysis of patents and further extends the use of molecular networks to explore structure-activity relationships.

  9. Surface study of organopalladium molecules on S-terminated GaAs

    International Nuclear Information System (INIS)

    Konishi, Tomoya; Toujyou, Takashi; Ishikawa, Takuma; Teraoka, Teruki; Ueta, Yukiko; Kihara, Yoshifumi; Moritoki, Hideji; Tono, Tatsuo; Musashi, Mio; Tada, Takashi; Tsukamoto, Shiro; Nishiwaki, Nagatoshi; Fujikawa, Seiji; Takahasi, Masamitu; Bell, Gavin; Shimoda, Masahiko

    2011-01-01

    Organopalladium species ({Pd}) immobilized on an S-terminated GaAs substrate (S/GaAs) effectively catalyzes C-C bond formation in the Mizoroki-Heck reaction with cycle durability. However, the immobilizing mechanism of {Pd} is unknown. In this study, we deposited Pd(OCOCH 3 ) 2 on S/GaAs in two different methods, namely dry-physical vapor-deposition and wetchemical deposition, and compared the catalytic activities in the Mizoroki-Heck reaction. Also, S-termination and {Pd}-immobilization on GaAs grains were performed by the wet-chemical method to monitor the change in the surface chemical structure during the preparation process with diffuse reflectance Fourier transform infrared spectroscopy (FT-IR). FT-IR measurements implied that the immobilization of catalytic active {Pd} was related to the OH groups on the S-terminated surface. {Pd}-S/GaAs prepared dryphysically showed poor catalytic activity, because {Pd} was not immobilized under absence of OH groups. (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  10. Protein immobilization on epoxy-activated thin polymer films: effect of surface wettability and enzyme loading.

    Science.gov (United States)

    Chen, Bo; Pernodet, Nadine; Rafailovich, Miriam H; Bakhtina, Asya; Gross, Richard A

    2008-12-02

    A series of epoxy-activated polymer films composed of poly(glycidyl methacrylate/butyl methacrylate/hydroxyethyl methacrylate) were prepared. Variation in comonomer composition allowed exploration of relationships between surface wettability and Candida antartica lipase B (CALB) binding to surfaces. By changing solvents and polymer concentrations, suitable conditions were developed for preparation by spin-coating of uniform thin films. Film roughness determined by AFM after incubation in PBS buffer for 2 days was less than 1 nm. The occurrence of single CALB molecules and CALB aggregates at surfaces was determined by AFM imaging and measurements of volume. Absolute numbers of protein monomers and multimers at surfaces were used to determine values of CALB specific activity. Increased film wettability, as the water contact angle of films increased from 420 to 550, resulted in a decreased total number of immobilized CALB molecules. With further increases in the water contact angle of films from 55 degrees to 63 degrees, there was an increased tendency of CALB molecules to form aggregates on surfaces. On all flat surfaces, two height populations, differing by more than 30%, were observed from height distribution curves. They are attributed to changes in protein conformation and/or orientation caused by protein-surface and protein-protein interactions. The fraction of molecules in these populations changed as a function of film water contact angle. The enzyme activity of immobilized films was determined by measuring CALB-catalyzed hydrolysis of p-nitrophenyl butyrate. Total enzyme specific activity decreased by decreasing film hydrophobicity.

  11. Active micromixer using surface acoustic wave streaming

    Science.gov (United States)

    Branch,; Darren W. , Meyer; Grant D. , Craighead; Harold, G [Ithaca, NY

    2011-05-17

    An active micromixer uses a surface acoustic wave, preferably a Rayleigh wave, propagating on a piezoelectric substrate to induce acoustic streaming in a fluid in a microfluidic channel. The surface acoustic wave can be generated by applying an RF excitation signal to at least one interdigital transducer on the piezoelectric substrate. The active micromixer can rapidly mix quiescent fluids or laminar streams in low Reynolds number flows. The active micromixer has no moving parts (other than the SAW transducer) and is, therefore, more reliable, less damaging to sensitive fluids, and less susceptible to fouling and channel clogging than other types of active and passive micromixers. The active micromixer is adaptable to a wide range of geometries, can be easily fabricated, and can be integrated in a microfluidic system, reducing dead volume. Finally, the active micromixer has on-demand on/off mixing capability and can be operated at low power.

  12. Application of Optical Biosensors in Small-Molecule Screening Activities

    Directory of Open Access Journals (Sweden)

    Wolfgang Knecht

    2012-03-01

    Full Text Available The last two decades have seen remarkable progress and improvements in optical biosensor systems such that those are currently seen as an important and value-adding component of modern drug screening activities. In particular the introduction of microplate-based biosensor systems holds the promise to match the required throughput without compromising on data quality thus representing a sought-after complement to traditional fluidic systems. This article aims to highlight the application of the two most prominent optical biosensor technologies, namely surface plasmon resonance (SPR and optical waveguide grating (OWG, in small-molecule screening and will present, review and discuss the advantages and disadvantages of different assay formats on these platforms. A particular focus will be on the specific advantages of the inhibition in solution assay (ISA format in contrast to traditional direct binding assays (DBA. Furthermore we will discuss different application areas for both fluidic as well as plate-based biosensor systems by considering the individual strength of the platforms.

  13. Novel Molecular Non-Volatile Memory: Application of Redox-Active Molecules

    Directory of Open Access Journals (Sweden)

    Hao Zhu

    2015-12-01

    Full Text Available This review briefly describes the development of molecular electronics in the application of non-volatile memory. Molecules, especially redox-active molecules, have become interesting due to their intrinsic redox behavior, which provides an excellent basis for low-power, high-density and high-reliability non-volatile memory applications. Recently, solid-state non-volatile memory devices based on redox-active molecules have been reported, exhibiting fast speed, low operation voltage, excellent endurance and multi-bit storage, outperforming the conventional floating-gate flash memory. Such high performance molecular memory will lead to promising on-chip memory and future portable/wearable electronics applications.

  14. Effect of nontronite smectite clay on the chemical evolution of several organic molecules under simulated Mars surface UV radiation conditions

    Science.gov (United States)

    Poch, Olivier; Dequaire, Tristan; Stalport, Fabien; Jaber, Maguy; Lambert, Jean-François; Szopa, Cyril; Coll, Patrice

    2015-04-01

    The search for organic carbon-containing molecules at the surface of Mars, as clues of past habitability or remnants of life, is a major scientific goal for Mars exploration. Several lines of evidence, including the detection of phyllosilicates, suggest that early Mars offered favorable conditions for long-term sustaining of water. As a consequence, we can assume that in those days, endogenous chemical processes, or even primitive life, may have produced organic matter on Mars. Moreover, exogenous delivery from small bodies or dust particles is likely to have brought fresh organic molecules to the surface of Mars up today. Organic matter is therefore expected to be present at the surface/subsurface of the planet. But the current environmental conditions at the surface - UV radiation, oxidants and energetic particles - generate physico-chemical processes that may affect organic molecules. On the other hand, on Earth, phyllosilicates are known to accumulate and preserve organic matter. But are phyllosilicates efficient at preserving organic molecules under the current environmental conditions at the surface of Mars? We have monitored the qualitative and quantitative evolutions of glycine, urea and adenine interacting with the Fe3+-smectite clay nontronite, one of the most abundant phyllosilicates present at the surface of Mars, under simulated Martian surface ultraviolet light (190-400 nm), mean temperature (218 ± 2 K) and pressure (6 ± 1 mbar) in a laboratory simulation setup. We have tested organic-rich samples which may be representative of the evaporation of a warm little pond of liquid water having concentrated organics on Mars. For each molecule, we have observed how the nontronite influences the quantum efficiency of its photodecomposition and the nature of its solid evolution products. The results reveal a pronounced photoprotective effect of nontronite on the evolution of glycine and adenine: their efficiencies of photodecomposition are reduced by a factor

  15. Technical activities, 1990: Surface Science Division

    International Nuclear Information System (INIS)

    Powell, C.J.

    1991-05-01

    The report summarizes technical activities and accomplishments of the NIST Surface Science Division during Fiscal Year 1990. Overviews are presented of the Division and of its three constituent groups: Surface Dynamical Processes, Thin Films and Interfaces, and Surface Spectroscopies and Standards. These overviews are followed by reports of selected technical accomplishments during the year. A summary is given of Division outputs and interactions that includes lists of publications, talks, committee assignments, seminars (including both Division seminars and Interface Science seminars arranged through the Division), conferences organized, and a standard reference material certified. Finally, lists are given of Division staff and of guest scientists who have worked in the Division during the past year

  16. Interrogating the activities of conformational deformed enzyme by single-molecule fluorescence-magnetic tweezers microscopy

    Science.gov (United States)

    Guo, Qing; He, Yufan; Lu, H. Peter

    2015-01-01

    Characterizing the impact of fluctuating enzyme conformation on enzymatic activity is critical in understanding the structure–function relationship and enzymatic reaction dynamics. Different from studying enzyme conformations under a denaturing condition, it is highly informative to manipulate the conformation of an enzyme under an enzymatic reaction condition while monitoring the real-time enzymatic activity changes simultaneously. By perturbing conformation of horseradish peroxidase (HRP) molecules using our home-developed single-molecule total internal reflection magnetic tweezers, we successfully manipulated the enzymatic conformation and probed the enzymatic activity changes of HRP in a catalyzed H2O2–amplex red reaction. We also observed a significant tolerance of the enzyme activity to the enzyme conformational perturbation. Our results provide a further understanding of the relation between enzyme behavior and enzymatic conformational fluctuation, enzyme–substrate interactions, enzyme–substrate active complex formation, and protein folding–binding interactions. PMID:26512103

  17. Transcriptional tools: Small molecules for modulating CBP KIX-dependent transcriptional activators.

    Science.gov (United States)

    Bates, Caleb A; Pomerantz, William C; Mapp, Anna K

    2011-01-01

    Previously it was demonstrated that amphipathic isoxazolidines are able to functionally replace the transcriptional activation domains of endogenous transcriptional activators. In addition, in vitro binding studies suggested that a key binding partner of these molecules is the CREB Binding Protein (CBP), more specifically the KIX domain within this protein. Here we show that CBP plays an essential role in the ability of isoxazolidine transcriptional activation domains to activate transcription in cells. Consistent with this model, isoxazolidines are able to function as competitive inhibitors of the activators MLL and Jun, both of which utilize a binding interaction with KIX to up-regulate transcription. Further, modification of the N2 side chain produced three analogs with enhanced potency against Jun-mediated transcription, although increased cytotoxicity was also observed. Collectively these small KIX-binding molecules will be useful tools for dissecting the role of the KIX domain in a variety of pathological processes. 2010 Wiley Periodicals, Inc.

  18. The neural cell adhesion molecule L1 is distinct from the N-CAM related group of surface antigens BSP-2 and D2

    DEFF Research Database (Denmark)

    Faissner, A; Kruse, J; Goridis, C

    1984-01-01

    The neural cell adhesion molecule L1 and the group of N-CAM related molecules, BSP-2 and D2 antigen, are immunochemically distinct molecular species. The two groups of surface molecules are also functionally distinct entities, since inhibition of Ca2+-independent adhesion among early post-natal m...

  19. JCMT active surface control system: implementation

    Science.gov (United States)

    Smith, Ian A.

    1998-05-01

    The James Clerk Maxwell Telescope on the summit of Mauna Kea in Hawaii is a 15 meter sub-millimeter telescope which operates in the 350 microns to 2 millimeter region. The primary antenna surface consists of 276 panels, each of which is positioned by 3 stepper motors. In order to achieve the highest possible surface accuracy we are embarking upon a project to actively control the position of the panels adjuster system is based on a 6809 micro connected to the control computer by a GPIB interface. This system is slow and inflexible and it would prove difficult to build an active surface control system with it. Part of the upgrade project is to replace the existing micro with a 68060 VME micro. The poster paper will describe how the temperature of the antenna is monitored with the new system, how a Finite Element Analyses package transforms temperature changes into a series of panel adjuster moves, and how these moves are then applied to the surface. The FEA package will run on a high end Sun workstation. A series of DRAMA tasks distributed between the workstation and the Baja 68060 VxWorks Active Surface Control System micro will control the temperature monitoring, FEA and panel adjustment activities. Users can interact with the system via a Tcl/TK based GUI.

  20. Theoretical studies of molecule surface scattering: Rotationally inelastic diffraction and dissociative dynamics of H2 on metals

    International Nuclear Information System (INIS)

    Cruz Pol, A.J.

    1993-01-01

    The interaction of H 2 and its isotopes with metal surfaces has been the subject of many investigations. The scattering experiments provide data such as the final rotational state distribution, sticking coefficients, kinetic energy distribution, and diffraction data. In the first study of this thesis the author implemented a model for looking at the rotationally inelastic diffraction probabilities for H 2 , HD, and D 2 , as a function of surface temperature. The surface is treated in a quantum mechanical fashion using a recently developed formalism. The center of mass translational motion is treated semiclassically using Gaussian wave packets, and the rotations are described quantum mechanically. The phonon summed rotation-diffraction probabilities as well as the probability distribution for a scattering molecule exchanging an amount of energy ΔE with the surface were computed. In the second and third study of this thesis the author implemented a mixed quantum-classical model to compute the probability for dissociation and rotational excitation for H 2 , HD, and D 2 scattered from Ni(100) dimensionally in dynamics simulations. Of the six degrees of freedom for the dissociative adsorption of a diatomic molecule on a static surface, the author treats Z,d the center of mass distance above the surface plan, r, the internuclear separation, θ, the polar orientation angle, quantum mechanically. The remaining three degrees of freedom, X and Y, the center of mass position on the surface plane, and oe, the azimuthal orientation angle, are treated classically. Probabilities for dissociation and ro-vibrational excitation are computed as a function of incident translational energy. Two sudden approximations are tested, in which either the center of mass translation parallel to the surface or the azimuthal orientation of the molecule are frozen. Comparisons are made between low and high dimensionality results and with fully classical results

  1. Synthesis of molecules of biological interest labelled with high specific activity tritium

    International Nuclear Information System (INIS)

    Petillot, Yves

    1975-01-01

    Labelled molecules are artificial organic compounds possessing one or several radioactive or steady isotopic atoms. Using tritium to label molecules presents several benefits: a raw material easy to obtain with a high purity and at reasonable cost; synthesised labelled molecules displaying high specific activities very interesting in molecular biology; high resolution of radiographies; relatively simple and quick introduction of tritium atoms in complex molecules. Thus, this report for graduation in organic chemistry addresses the synthesis and study of new labelled molecules which belong to families of organic compounds which have fundamental activities in biology: uridine 3 H-5,6 and thymidine 3 H-methyl which are nucleotides which intervene under the form of phosphates in the synthesis of nucleic acids, oestradiol 3 H-2,4,6,7 which is a powerful estrogenic hormone which naturally secreted by the ovary; and noradrenaline 3 H-1,1' and dopamine 3 H-1,2 which are usually secreted by adrenal medulla and have multiple actions on the nervous system

  2. Controlling hydrogenation activity and selectivity of bimetallic surfaces and catalysts

    Science.gov (United States)

    Murillo, Luis E.

    Studies of bimetallic systems are of great interest in catalysis due to the novel properties that they often show in comparison with the parent metals. The goals of this dissertation are: (1) to expand the studies of self-hydrogenation and hydrogenation reactions on bimetallic surfaces under ultra high vacuum conditions (UHV) using different hydrocarbon as probe molecules; (2) to attempt to correlate the surface science findings with supported catalyst studies under more realistic conditions; and (3) to investigate the competitive hydrogenation of C=C versus C=O bonds on Pt(111) modified by different 3d transition metals. Hydrogenation studies using temperature programmed desorption (TPD) on Ni/Pt(111) bimetallic surfaces have demonstrated an enhancement in the low temperature hydrogenation activity relative to that of clean Pt(111). This novel hydrogenation pathway can be achieved under UHV conditions by controlling the structures of the bimetallic surfaces. A low temperature hydrogenation activity of 1-hexene and 1-butene has been observed on a Pt-Ni-Pt(111) subsurface structure, where Ni atoms are mainly present on the second layer of the Pt(111) single crystal. These results are in agreement with previous studies of self-hydrogenation and hydrogenation of cyclohexene. However, a much higher dehydrogenation activity is observed in the reaction of cyclohexene to produce benzene, demonstrating that the hydrocarbon structure has an effect on the reaction pathways. On the other hand, self-hydrogenation of 1-butene is not observed on the Pt-Ni-Pt(111) surface, indicating that the chain length (or molecular weight) has a significant effect on the selfhydrogenation activity. The gas phase reaction of cyclohexene on Ni/Pt supported on alumina catalysts has also shown a higher self-hydrogenation activity in comparison with the same reaction performed on supported monometallic catalysts. The effects of metal loading and impregnation sequence of the metal precursors are

  3. Antimicrobial activity of innate immune molecules against Streptococcus pneumoniae, Moraxella catarrhalis and nontypeable Haemophilus influenzae

    Directory of Open Access Journals (Sweden)

    Teufert Karen

    2004-05-01

    Full Text Available Abstract Background Despite its direct connection to the nasopharynx which harbors otitis media pathogens as part of its normal flora, the middle ear cavity is kept free of these bacteria by as yet unknown mechanisms. Respiratory mucosal epithelia, including those of the middle ear and eustachian tube, secrete antimicrobial effectors including lysozyme, lactoferrin and β defensins-1 and -2. To elucidate the role of these innate immune molecules in the normal defense and maintenance of sterility of respiratory mucosa such as that of the middle ear, we assessed their effect on the respiratory pathogens nontypeable Haemophilus influenzae (NTHi 12, Moraxella catarrhalis 035E, and Streptococcus pneumoniae 3, and 6B. Methods Two assay methods, the radial assay and the liquid broth assay, were employed for testing the antimicrobial activity of the molecules. This was done in order to minimize the possibility that the observed effects were artifacts of any single assay system employed. Also, transmission electron microscopy (TEM was employed to evaluate the effect of antimicrobial innate immune molecules on OM pathogens. For the statistical analysis of the data, Student's t-test was performed. Results Results of the radial diffusion assay showed that β defensin-2 was active against all four OM pathogens tested, while treatment with β defensin-1 appeared to only affect M. catarrhalis. The radial assay results also showed that lysozyme was quite effective against S. pneumoniae 3 and 6B and was partially bacteriostatic/bactericidal against M. catarrhalis. Lysozyme however, appeared not to affect the growth of NTHi. Thus, lysozyme seems to have a more pronounced impact on the growth of the Gram-positive S. pneumoniae as compared to that of Gram-negative pathogens. Lactoferrin on the other hand, enhanced the growth of the bacteria tested. The results of the radial assays were confirmed using liquid broth assays for antimicrobial activity, and showed that

  4. The Cytolytically Inactive Terminal Complement Complex Activates Endothelial Cells to Express Adhesion Molecules and Tissue Factor Procoagulant Activity

    Science.gov (United States)

    Tedesco, Francesco; Pausa, Mario; Nardon, Ermanno; Introna, Martino; Mantovani, Alberto; Dobrina, Aldo

    1997-01-01

    The membrane attack complex of complement (C) in sublytic concentrations stimulates endothelial cells (EC) to express adhesion molecules and to release biologically active products. We have examined the ability of a cytolytically inactive form of this complex, which is incapable of inserting into the cell membrane, to upregulate the expression of adhesion molecules and of tissue factor (TF) procoagulant activity. The inactive terminal C complex (iTCC) was prepared by mixing C5b6, C7, C8, and C9 and was purified by fast protein liquid chromatography on a Superose 12 column. Binding of this complex to EC was found to be dose dependent and was inhibited by anti-C9 antibodies, as assessed both by ELISA using an mAb anti-C9 neoantigen and by measuring cell-bound 125I-labeled iTCC. Exposure of EC to iTCC resulted in a dose- and time-dependent expression of endothelial leukocyte adhesion molecule 1, intercellular adhesion molecule 1, and vascular cell adhesion molecule 1 accompanied by increased levels of the corresponding mRNA, but not in the rapid expression of P-selectin. Inactive TCC also induced increased TF activity evaluated by a chromogenic assay that measures the formation of factor Xa. These effects were inhibited by anti-C9 antibodies. The data support the conclusion that iTCC may induce proinflammatory and procoagulant activities on EC. PMID:9151899

  5. Hydration processes of electrolyte anions and cations on pt(111), Ir(111), Ru(001) and Au(111) surfaces: coadsorption of water molecules with electrolyte ions.

    Science.gov (United States)

    Ito, M; Nakamura, M

    2002-01-01

    Water adsorption on Pt( 111) and Ru(001) treated with oxygen, hydrogen chloride and sodium atom at 20 K has been studied by Fourier transform infrared spectroscopy, scanning tunneling microscopy and surface X-ray diffraction. Water molecules chemisorb predominantly on the sites of the electronegative additives, forming hydrogen bonds. Three types of hydration water molecules coordinate to an adsorbed Na atom through an oxygen lone pair. In contrast, water molecules adsorb on electrode surfaces in a simple way in solution. In 1 mM CuSO4 + 0.5 M H2SO4 solution on an Au(111) electrode surface, water molecules coadsorb not only with sulfuric acid anions through hydrogen bonding but also with copper, over wide potential ranges. In the first stage of underpotential deposition (UPD), each anion is accommodated by six copper hexagon (honeycomb) atoms on which water molecules dominate. At any UPD stage water molecules interact with both the copper atom and sulfuric acid anions on the Au(111) surface. Water molecules also coadsorb with CO molecules on the surface of 2 x 2-2CO-Ru(001). All of the hydration water molecules chemisorb weakly on the surfaces. There appears to be a correlation between the orientation of hydrogen bonding water molecules and the electrode potential.

  6. Single-active-electron potentials for molecules in intense laser fields

    DEFF Research Database (Denmark)

    Abu-Samha, Mahmoud; Madsen, Lars Bojer

    2010-01-01

    Single-active-electron potentials are computed for selected molecules, and molecular wave functions with the correct asymptotic behavior are produced. Asymptotic expansion coefficients are extracted from the wave functions and used to compute alignment-dependent ionization yields from molecular t...

  7. Immune complement activation is attenuated by surface nanotopography

    Directory of Open Access Journals (Sweden)

    Elwing H

    2011-10-01

    Full Text Available Mats Hulander1, Anders Lundgren1, Mattias Berglin1, Mattias Ohrlander2, Jukka Lausmaa3,4, Hans Elwing1 1Department of Cell and Molecular Biology/Interface Biophysics, University of Gothenburg, Medicinaregatan 9E, Gothenburg, 2Bactiguard AB, Stockholm, 3SP Technical Research Institute, Boras, 4Biomatcell, The Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden Abstract: The immune complement (IC is a cell-free protein cascade system, and the first part of the innate immune system to recognize foreign objects that enter the body. Elevated activation of the system from, for example, biomaterials or medical devices can result in both local and systemic adverse effects and eventually loss of function or rejection of the biomaterial. Here, the researchers have studied the effect of surface nanotopography on the activation of the IC system. By a simple nonlithographic process, gold nanoparticles with an average size of 58 nm were immobilized on a smooth gold substrate, creating surfaces where a nanostructure is introduced without changing the surface chemistry. The activation of the IC on smooth and nanostructured surfaces was viewed with fluorescence microscopy and quantified with quartz crystal microbalance with dissipation monitoring in human serum. Additionally, the ability of pre-adsorbed human immunoglobulin G (IgG (a potent activator of the IC to activate the IC after a change in surface hydrophobicity was studied. It was found that the activation of the IC was significantly attenuated on nanostructured surfaces with nearly a 50% reduction, even after pre-adsorption with IgG. An increase in surface hydrophobicity blunted this effect. The possible role of the curvature of the nanoparticles for the orientation of adsorbed IgG molecules, and how this can affect the subsequent activation of the IC, are discussed. The present findings are important for further understanding of how surface nanotopography affects complex protein

  8. Luminescent systems based on the isolation of conjugated PI systems and edge charge compensation with polar molecules on a charged nanostructured surface

    Science.gov (United States)

    Ivanov, Ilia N.; Puretzky, Alexander A.; Zhao, Bin; Geohegan, David B.; Styers-Barnett, David J.; Hu, Hui

    2014-07-15

    A photoluminescent or electroluminescent system and method of making a non-luminescent nanostructured material into such a luminescent system is presented. The method of preparing the luminescent system, generally, comprises the steps of modifying the surface of a nanostructured material to create isolated regions to act as luminescent centers and to create a charge imbalance on the surface; applying more than one polar molecule to the charged surface of the nanostructured material; and orienting the polar molecules to compensate for the charge imbalance on the surface of the nanostructured material. The compensation of the surface charge imbalance by the polar molecules allows the isolated regions to exhibit luminescence.

  9. The detection of small organic molecules based on novel functionalized surface plasmon resonance sensors

    Science.gov (United States)

    Zheng, Rui; Cameron, Brent D.

    2010-02-01

    The objective of this study was to develop rapid, inexpensive, and easily applied in vivo phenotyping strategies for characterizing drug-metabolizing phenotypes with reference to the cytochrome P450 (CYP) enzymes in biological fluids. Therefore, the accurate detection of low concentration of theophylline, which can be used as a probe for cytochrome P450 (CYP450) enzymes (e.g. CYP1A2) activity, could benefit drug-metabolizing studies. In this study, a portable, specific, and sensitive functionalized surface plasmon resonance (SPR) sensor using polyacrylamide molecularly imprinted polymers (MIPs) as the highly specific selector is developed for the detection of low concentration theophylline in the presence of other confounding components, such as, caffeine which has a very similar chemical structure.

  10. Bactericidal activity of biomimetic diamond nanocone surfaces.

    Science.gov (United States)

    Fisher, Leanne E; Yang, Yang; Yuen, Muk-Fung; Zhang, Wenjun; Nobbs, Angela H; Su, Bo

    2016-03-17

    The formation of biofilms on implant surfaces and the subsequent development of medical device-associated infections are difficult to resolve and can cause considerable morbidity to the patient. Over the past decade, there has been growing recognition that physical cues, such as surface topography, can regulate biological responses and possess bactericidal activity. In this study, diamond nanocone-patterned surfaces, representing biomimetic analogs of the naturally bactericidal cicada fly wing, were fabricated using microwave plasma chemical vapor deposition, followed by bias-assisted reactive ion etching. Two structurally distinct nanocone surfaces were produced, characterized, and the bactericidal ability examined. The sharp diamond nanocone features were found to have bactericidal capabilities with the surface possessing the more varying cone dimension, nonuniform array, and decreased density, showing enhanced bactericidal ability over the more uniform, highly dense nanocone surface. Future research will focus on using the fabrication process to tailor surface nanotopographies on clinically relevant materials that promote both effective killing of a broader range of microorganisms and the desired mammalian cell response. This study serves to introduce a technology that may launch a new and innovative direction in the design of biomaterials with capacity to reduce the risk of medical device-associated infections.

  11. High-resolution neutron-scattering study of slow dynamics of surface water molecules in zirconium oxide.

    Science.gov (United States)

    Mamontov, E

    2005-07-08

    We have performed a quasielastic neutron-scattering experiment on backscattering spectrometer with sub-mueV resolution to investigate the slow dynamics of surface water in zirconium oxide using the sample studied previously with a time-of-flight neutron spectrometer [E. Mamontov, J. Chem. Phys. 121, 9087 (2004)]. The backscattering measurements in the temperature range of 240-300 K have revealed a translational dynamics slower by another order of magnitude compared to the translational dynamics of the outer hydration layer observed in the time-of-flight experiment. The relaxation function of this slow motion is described by a stretched exponential with the stretch factors between 0.8 and 0.9, indicating a distribution of the relaxation times. The temperature dependence of the average residence time is non-Arrhenius, suggesting that the translational motion studied in this work is more complex than surface jump diffusion previously observed for the molecules of the outer hydration layer. The observed slow dynamics is ascribed to the molecules of the inner hydration layer that form more hydrogen bonds compared to the molecules of the outer hydration layer. Despite being slower by two orders of magnitude, the translational motion of the molecules of the inner hydration layer may have more in common with bulk water compared to the outer hydration layer, the dynamics of which is slower than that of bulk water by just one order of magnitude.

  12. Activation of interfacial enzymes at membrane surfaces

    DEFF Research Database (Denmark)

    Mouritsen, Ole G.; Andresen, Thomas Lars; Halperin, Avi

    2006-01-01

    A host of water-soluble enzymes are active at membrane surfaces and in association with membranes. Some of these enzymes are involved in signalling and in modification and remodelling of the membranes. A special class of enzymes, the phospholipases, and in particular secretory phospholipase A2 (s...

  13. Plasma-Surface Interaction Activities in KSTAR

    NARCIS (Netherlands)

    Hong, S. H.; Yu, Y.; Kim, K. P.; Bak, J. G.; Park, H. J.; Oh, Y. S.; Chung, J.; Nam, Y. U.; Bang, E. N.; Kim, K. R.; Litnovsky, A.; Hellwig, M.; Matveev, D.; Komm, M.; van den Berg, M. A.; Kim, W. C.; Kim, H. K.; Rho, T. H.; Chu, Y.; Oh, Y. K.; Yang, H. L.; Park, K. R.; Chung, K. S.; Kstar Team,

    2013-01-01

    Selected topics of Plasma-Surface Interaction (PSI) activities in KSTAR are briefly introduced. SOL parameter measurements, particle balance and fuel retention, in-vessel dust research, and finally tungsten R & D are discussed. Some quantitative numbers from the initial phase of the operation

  14. [Progress of methodology for identifying target protein of natural active small molecules].

    Science.gov (United States)

    Tu, Peng-Fei; Zeng, Ke-Wu; Liao, Li-Xi; Song, Xiao-Min

    2016-01-01

    Drug targets are special molecules that can interact with drugs and exert pharmacological functions in human body. The natural active small molecules are the bioactive basis of traditional Chinese medicine, and the mechanism study is a hot topic now, especially for the identification of their target proteins. However, little progress has been made in this field until now. Here, we summarized the recent technologies and methods for the identification of target proteins of natural bioactive small molecules, and introduced the main research methods, principles and successful cases in this field. We also explored the applicability and discussed the advantages and disadvantages among different methods. We hope this review can be used as a reference for the researchers who engaged in natural pharmaceutical chemistry, pharmacology and chemical biology. Copyright© by the Chinese Pharmaceutical Association.

  15. Interaction of an immunodominant epitope with Ia molecules in T-cell activation

    DEFF Research Database (Denmark)

    Adorini, L; Sette, A; Buus, S

    1988-01-01

    but not the binding to I-Ed molecules, whereas, as shown by binding data and competition experiments, an Arg----His substitution at position 114 profoundly impairs the capacity of the peptide to interact with I-Ed molecules. In agreement with these results, [Lys113]HEL-(105-120)-peptide but not [His114]HEL-(105......-120)-peptide binds to I-Ed but not to I-Ad molecules. Conservative or semiconservative substitutions at positions 113 (Asn----Lys), 114 (Arg----His), or 115 (Cys----Ala) abrogate the ability of HEL-(105-120) to activate T cells. Substitutions at residues 113 and 115 affect T-cell recognition...

  16. Mechanotransductive surfaces for reversible biocatalysis activation

    Science.gov (United States)

    Mertz, Damien; Vogt, Cédric; Hemmerlé, Joseph; Mutterer, Jérôme; Ball, Vincent; Voegel, Jean-Claude; Schaaf, Pierre; Lavalle, Philippe

    2009-09-01

    Fibronectin, like other proteins involved in mechanotransduction, has the ability to exhibit recognition sites under mechanical stretch. Such cryptic sites are buried inside the protein structure in the native fold and become exposed under an applied force, thereby activating specific signalling pathways. Here, we report the design of new active polymeric nanoassembled surfaces that show some similarities to these cryptic sites. These nanoassemblies consist of a first polyelectrolyte multilayer stratum loaded with enzymes and capped with a second polyelectrolyte multilayer acting as a mechanically sensitive nanobarrier. The biocatalytic activity of the film is switched on/off reversibly by mechanical stretching, which exposes enzymes through the capping barrier, similarly to mechanisms involved in proteins during mechanotransduction. This first example of a new class of biologically inspired surfaces should have great potential in the design of various devices aimed to trigger and modulate chemical reactions by mechanical action with applications in the field of microfluidic devices or mechanically controlled biopatches for example.

  17. Screening Mixtures of Small Molecules for Binding to Multiple Sites on the Surface Tetanus Toxin C Fragment by Bioaffinity NMR

    Energy Technology Data Exchange (ETDEWEB)

    Cosman, M; Zeller, L; Lightstone, F C; Krishnan, V V; Balhorn, R

    2002-01-01

    The clostridial neurotoxins include the closely related tetanus (TeNT) and botulinum (BoNT) toxins. Botulinum toxin is used to treat severe muscle disorders and as a cosmetic wrinkle reducer. Large quantities of botulinum toxin have also been produced by terrorists for use as a biological weapon. Because there are no known antidotes for these toxins, they thus pose a potential threat to human health whether by an accidental overdose or by a hostile deployment. Thus, the discovery of high specificity and affinity compounds that can inhibit their binding to neural cells can be used as antidotes or in the design of chemical detectors. Using the crystal structure of the C fragment of the tetanus toxin (TetC), which is the cell recognition and cell surface binding domain, and the computational program DOCK, sets of small molecules have been predicted to bind to two different sites located on the surface of this protein. While Site-1 is common to the TeNT and BoNTs, Site-2 is unique to TeNT. Pairs of these molecules from each site can then be linked together synthetically to thereby increase the specificity and affinity for this toxin. Electrospray ionization mass spectroscopy was used to experimentally screen each compound for binding. Mixtures containing binders were further screened for activity under biologically relevant conditions using nuclear magnetic resonance (NMR) methods. The screening of mixtures of compounds offers increased efficiency and throughput as compared to testing single compounds and can also evaluate how possible structural changes induced by the binding of one ligand can influence the binding of the second ligand. In addition, competitive binding experiments with mixtures containing ligands predicted to bind the same site could identify the best binder for that site. NMR transfer nuclear Overhauser effect (trNOE) confirm that TetC binds doxorubicin but that this molecule is displaced by N-acetylneuraminic acid (sialic acid) in a mixture that

  18. Screening Mixtures of Small Molecules for Binding to Multiple Sites on the Surface Tetanus Toxin C Fragment by Bioaffinity NMR

    International Nuclear Information System (INIS)

    Cosman, M; Zeller, L; Lightstone, F C; Krishnan, V V; Balhorn, R

    2002-01-01

    The clostridial neurotoxins include the closely related tetanus (TeNT) and botulinum (BoNT) toxins. Botulinum toxin is used to treat severe muscle disorders and as a cosmetic wrinkle reducer. Large quantities of botulinum toxin have also been produced by terrorists for use as a biological weapon. Because there are no known antidotes for these toxins, they thus pose a potential threat to human health whether by an accidental overdose or by a hostile deployment. Thus, the discovery of high specificity and affinity compounds that can inhibit their binding to neural cells can be used as antidotes or in the design of chemical detectors. Using the crystal structure of the C fragment of the tetanus toxin (TetC), which is the cell recognition and cell surface binding domain, and the computational program DOCK, sets of small molecules have been predicted to bind to two different sites located on the surface of this protein. While Site-1 is common to the TeNT and BoNTs, Site-2 is unique to TeNT. Pairs of these molecules from each site can then be linked together synthetically to thereby increase the specificity and affinity for this toxin. Electrospray ionization mass spectroscopy was used to experimentally screen each compound for binding. Mixtures containing binders were further screened for activity under biologically relevant conditions using nuclear magnetic resonance (NMR) methods. The screening of mixtures of compounds offers increased efficiency and throughput as compared to testing single compounds and can also evaluate how possible structural changes induced by the binding of one ligand can influence the binding of the second ligand. In addition, competitive binding experiments with mixtures containing ligands predicted to bind the same site could identify the best binder for that site. NMR transfer nuclear Overhauser effect (trNOE) confirm that TetC binds doxorubicin but that this molecule is displaced by N-acetylneuraminic acid (sialic acid) in a mixture that

  19. Active colloidal propulsion over a crystalline surface

    Science.gov (United States)

    Choudhury, Udit; Straube, Arthur V.; Fischer, Peer; Gibbs, John G.; Höfling, Felix

    2017-12-01

    We study both experimentally and theoretically the dynamics of chemically self-propelled Janus colloids moving atop a two-dimensional crystalline surface. The surface is a hexagonally close-packed monolayer of colloidal particles of the same size as the mobile one. The dynamics of the self-propelled colloid reflects the competition between hindered diffusion due to the periodic surface and enhanced diffusion due to active motion. Which contribution dominates depends on the propulsion strength, which can be systematically tuned by changing the concentration of a chemical fuel. The mean-square displacements (MSDs) obtained from the experiment exhibit enhanced diffusion at long lag times. Our experimental data are consistent with a Langevin model for the effectively two-dimensional translational motion of an active Brownian particle in a periodic potential, combining the confining effects of gravity and the crystalline surface with the free rotational diffusion of the colloid. Approximate analytical predictions are made for the MSD describing the crossover from free Brownian motion at short times to active diffusion at long times. The results are in semi-quantitative agreement with numerical results of a refined Langevin model that treats translational and rotational degrees of freedom on the same footing.

  20. Surface active properties of lipid nanocapsules.

    Directory of Open Access Journals (Sweden)

    Celia R A Mouzouvi

    Full Text Available Lipid nanocapsules (LNCs are biomimetic nanocarriers used for the encapsulation of a broad variety of active ingredients. Similar to surface active compounds, LNCs contain both hydrophilic and hydrophobic parts in their structure. Moreover, the components of LNCs, macrogol 15 hydroxystearate (MHS and lecithin, are known for their surface active properties. Therefore, the aim of this paper was to investigate the capability of the LNCs to decrease surface tension using two techniques: drop tensiometry and the Wilhelmy plate method. LNCs with diameters ranging from 30 to 100 nm were successfully obtained using a phase inversion technique. The LNCs' properties, such as size and zeta potential, depend on the composition. LNCs exhibit a lower limiting surface tension compared to MHS (34.8-35.0 mN/m and 37.7-38.8 mN/m, respectively, as confirmed by both drop tensiometry and the Wilhelmy plate method. LNCs have exhibited a saturated interfacial concentration (SIC that was 10-fold higher than the critical micellar concentration (CMC of MHS or the SIC of binary and ternary mixtures of LNC ingredients. The SIC of the LNC formulations depended on the mass mixing ratio of the MHS/triglycerides but not on the presence of lecithin. The CMC/SIC values measured by the Wilhelmy plate method were higher than those obtained using drop tensiometry because of the longer duration of the tensiometry measurement. In conclusion, the surfactant-like properties of the LNCs offer new possibilities for medical and pharmaceutical applications.

  1. Chemical activation of molecules by metals: Experimental studies of electron distributions and bonding

    International Nuclear Information System (INIS)

    Lichtenberger, D.L.

    1991-10-01

    The formal relationship between measured molecular ionization energies and thermodynamic bond dissociation energies has been developed into a single equation which unifies the treatment of covalent bonds, ionic bonds, and partially ionic bonds. This relationship has been used to clarify the fundamental thermodynamic information relating to metal-hydrogen, metal-alkyl, and metal-metal bond energies. We have been able to obtain a direct observation and measurement of the stabilization energy provided by the agostic interaction of the C-H bond with the metal. The ionization energies have also been used to correlate the rates of carbonyl substitution reactions of (η 5 -C 5 H 4 X)Rh(CO) 2 complexes, and to reveal the electronic factors that control the stability of the transition state. The extent that the electronic features of these bonding interactions transfer to other chemical systems is being investigated in terms of the principle of additivity of ligand electronic effects. Specific examples under study include metal- phosphines, metal-halides, and metallocenes. Especially interesting has been the recent application of these techniques to the characterization of the soccer-ball shaped C 60 molecule, buckminsterfullerene, and its interaction with a metal surface. The high-resolution valence ionizations in the gas phase reveal the high symmetry of the molecule, and studies of thin films of C 60 reveal weak intermolecular interactions. Scanning tunneling and atomic force microscopy reveal the arrangement of spherical molecules on gold substrates, with significant delocalization of charge from the metal surface. 21 refs

  2. Static force fields simulations of reduced CeO2 (110) surface: Structure and adsorption of H2O molecule

    Science.gov (United States)

    Vives, Serge; Meunier, Cathy

    2018-02-01

    The CeO2(110) surface properties are largely involved in the catalysis, energy and biological phenomenon. The Static Force Fields simulations are able to describe large atomic systems surface even if no information on the electronic structure can be obtained. We employ those simulations to study the formation of the neutral 2 CeCe‧ VO•• cluster. We focus on seven different cluster configurations and find that the defect formation energy is the lower for the 1N-2N configurations. Two geometries are possible, as it is the case for the ab initio studies, the in plane and the more stable bridging one. We evidence the modifications of the surface energy and the Potential Energy Surface due to the presence of the 2 CeCe‧ VO•• defect. The physical adsorption of a water molecule is calculated and the geometry described for all the cluster configurations. The H2O molecule physisorption stabilizes the Ce(110) surface and the presence of the 2 CeCe‧ VO•• defect increases this effect.

  3. First-principles study of the adsorption properties of atoms and molecules on UN2 (001) surface

    Science.gov (United States)

    Xu, Mengjuan; Liu, Guangdong; Ao, Bingyun; Chen, Piheng; Hu, Wangyu; Deng, Huiqiu

    2017-09-01

    Uranium nitrides are one kind of accident-tolerant fuels and have been paid more attention recently. With the first-principles Density-Functional Theory (DFT) calculations, the adsorptions properties of some typical atoms, molecules and radical (including O, H, H2, O2, H2O and OH) adsorbed on the UN2 (001) surface have been studied in the present work. The preferred sites and stable configurations for those adsorbates on the UN2 (001) surface have been obtained. It's found that O or H atom prefers to be adsorbed at the bridge site; O2 adsorption will dissociate into two O atoms and occupy the nearest neighbor bridge sites; the interaction between H2 molecule and the UN2 (001) surface is very weak; OH prefers to occupy the bridge site with its O-H bond vertical to the surface; the surface adsorption of H2O is non-dissociated and adsorption energies are dependent on the initial structures and adsorption modes.

  4. Effects of microwave electric fields on the translational diffusion of dipolar molecules in surface potential: A simulation study

    Science.gov (United States)

    Kapranov, Sergey V.; Kouzaev, Guennadi A.

    2018-01-01

    Variations of effective diffusion coefficient of polar molecules exposed to microwave electric fields in a surface potential are studied by solving coupled stochastic differential equations of motion with a deterministic component of the surface force. Being an essential tool for the simulation interpretation, a theoretical approach to effective diffusion in surface potential is first developed. The effective diffusion coefficient is represented as the product of the normal diffusion coefficient and potential-dependent correction function, whose temperature dependence is close to the Arrhenius form. The analytically found zero-diffusion condition defines the state of thermal equilibrium at the surface. The diffusion of a water-like dipole molecule in the potential of graphite surface is simulated in the field-free conditions and in the presence of the alternating electric fields of various magnitude intensities and frequencies. Temperature dependence of the correction function exhibits field-induced variations of the effective Lennard-Jones energy parameter. It demonstrates maximum departure from the zero-field value at certain frequencies and intensities, which is associated with variations in the rotational dynamics. A concept of the amplitude-frequency resonance put forward to interpret the simulation results is explained using a heuristic reasoning and is corroborated by semi-quantitative considerations in terms of the Dissado-Hill cluster theory of dielectric relaxation.

  5. Expansion Hamiltonian model for a diatomic molecule adsorbed on a surface: Vibrational states of the CO/Cu(100) system including surface vibrations

    Energy Technology Data Exchange (ETDEWEB)

    Meng, Qingyong, E-mail: mengqingyong@dicp.ac.cn [State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Zhongshan Road 457, 116023 Dalian (China); Meyer, Hans-Dieter, E-mail: hans-dieter.meyer@pci.uni-heidelberg.de [Theoretische Chemie, Physikalisch-Chemisches Institut, Ruprecht-Karls Universität Heidelberg, Im Neuenheimer Feld 229, D-69120 Heidelberg (Germany)

    2015-10-28

    Molecular-surface studies are often done by assuming a corrugated, static (i.e., rigid) surface. To be able to investigate the effects that vibrations of surface atoms may have on spectra and cross sections, an expansion Hamiltonian model is proposed on the basis of the recently reported [R. Marquardt et al., J. Chem. Phys. 132, 074108 (2010)] SAP potential energy surface (PES), which was built for the CO/Cu(100) system with a rigid surface. In contrast to other molecule-surface coupling models, such as the modified surface oscillator model, the coupling between the adsorbed molecule and the surface atoms is already included in the present expansion SAP-PES model, in which a Taylor expansion around the equilibrium positions of the surface atoms is performed. To test the quality of the Taylor expansion, a direct model, that is avoiding the expansion, is also studied. The latter, however, requests that there is only one movable surface atom included. On the basis of the present expansion and direct models, the effects of a moving top copper atom (the one to which CO is bound) on the energy levels of a bound CO/Cu(100) system are studied. For this purpose, the multiconfiguration time-dependent Hartree calculations are carried out to obtain the vibrational fundamentals and overtones of the CO/Cu(100) system including a movable top copper atom. In order to interpret the results, a simple model consisting of two coupled harmonic oscillators is introduced. From these calculations, the vibrational levels of the CO/Cu(100) system as function of the frequency of the top copper atom are discussed.

  6. Trafficking of MHC molecules to the cell surface creates dynamic protein patches.

    Science.gov (United States)

    Blumenthal, Daniel; Edidin, Michael; Gheber, Levi A

    2016-09-01

    Major histocompatibility complex class I (MHC-I) molecules signal infection or transformation by engaging receptors on T lymphocytes. The spatial organization of MHC-I on the plasma membranes is important for this engagement. We and others have shown that MHC-I molecules, like other membrane proteins, are not uniformly distributed, but occur in patches in the plasma membrane. Here, we describe the temporal details of MHC-I patch formation and combine them with the spatial details, which we have described earlier, to yield a comprehensive quantitative description of patch formation. MHC-I is delivered to the plasma membrane in clathrin-coated vesicles, arriving at a rate of ∼2.5×10(-3) μm(-1) min(-1) (or about two arrivals per minute over the whole cell). The vesicles dock and fuse at non-random, apparently targeted, locations on the membrane and the newly delivered MHC-I molecules form patches that are a few hundred nanometers in diameter. The patches are maintained at steady state by a dynamic equilibrium between the rate of delivery and the rate of hindered diffusion of MHC-I molecules out of the patches (caused by components of the actin cytoskeleton). © 2016. Published by The Company of Biologists Ltd.

  7. DNA Origami Directed Au Nanostar Dimers for Single-Molecule Surface-Enhanced Raman Scattering.

    Science.gov (United States)

    Tanwar, Swati; Haldar, Krishna Kanta; Sen, Tapasi

    2017-12-06

    We demonstrate the synthesis of Au nanostar dimers with tunable interparticle gap and controlled stoichiometry assembled on DNA origami. Au nanostars with uniform and sharp tips were immobilized on rectangular DNA origami dimerized structures to create nanoantennas containing monomeric and dimeric Au nanostars. Single Texas red (TR) dye was specifically attached in the junction of the dimerized origami to act as a Raman reporter molecule. The SERS enhancement factors of single TR dye molecules located in the conjunction region in dimer structures having interparticle gaps of 7 and 13 nm are 2 × 10 10 and 8 × 10 9 , respectively, which are strong enough for single analyte detection. The highly enhanced electromagnetic field generated by the plasmon coupling between sharp tips and cores of two Au nanostars in the wide conjunction region allows the accommodation and specific detection of large biomolecules. Such DNA-directed assembled nanoantennas with controlled interparticle separation distance and stoichiometry, and well-defined geometry, can be used as excellent substrates in single-molecule SERS spectroscopy and will have potential applications as a reproducible platform in single-molecule sensing.

  8. Osmium Atoms and Os2 Molecules Move Faster on Selenium-Doped Compared to Sulfur-Doped Boronic Graphenic Surfaces.

    Science.gov (United States)

    Barry, Nicolas P E; Pitto-Barry, Anaïs; Tran, Johanna; Spencer, Simon E F; Johansen, Adam M; Sanchez, Ana M; Dove, Andrew P; O'Reilly, Rachel K; Deeth, Robert J; Beanland, Richard; Sadler, Peter J

    2015-07-28

    We deposited Os atoms on S- and Se-doped boronic graphenic surfaces by electron bombardment of micelles containing 16e complexes [Os(p-cymene)(1,2-dicarba-closo-dodecarborane-1,2-diselenate/dithiolate)] encapsulated in a triblock copolymer. The surfaces were characterized by energy-dispersive X-ray (EDX) analysis and electron energy loss spectroscopy of energy filtered TEM (EFTEM). Os atoms moved ca. 26× faster on the B/Se surface compared to the B/S surface (233 ± 34 pm·s(-1) versus 8.9 ± 1.9 pm·s(-1)). Os atoms formed dimers with an average Os-Os distance of 0.284 ± 0.077 nm on the B/Se surface and 0.243 ± 0.059 nm on B/S, close to that in metallic Os. The Os2 molecules moved 0.83× and 0.65× more slowly than single Os atoms on B/S and B/Se surfaces, respectively, and again markedly faster (ca. 20×) on the B/Se surface (151 ± 45 pm·s(-1) versus 7.4 ± 2.8 pm·s(-1)). Os atom motion did not follow Brownian motion and appears to involve anchoring sites, probably S and Se atoms. The ability to control the atomic motion of metal atoms and molecules on surfaces has potential for exploitation in nanodevices of the future.

  9. Effect of nontronite smectite clay on the chemical evolution of several organic molecules under simulated martian surface ultraviolet radiation conditions.

    Science.gov (United States)

    Poch, Olivier; Jaber, Maguy; Stalport, Fabien; Nowak, Sophie; Georgelin, Thomas; Lambert, Jean-François; Szopa, Cyril; Coll, Patrice

    2015-03-01

    Most of the phyllosilicates detected at the surface of Mars today are probably remnants of ancient environments that sustained long-term bodies of liquid water at the surface or subsurface and were possibly favorable for the emergence of life. Consequently, phyllosilicates have become the main mineral target in the search for organics on Mars. But are phyllosilicates efficient at preserving organic molecules under current environmental conditions at the surface of Mars? We monitored the qualitative and quantitative evolutions of glycine, urea, and adenine in interaction with the Fe(3+)-smectite clay nontronite, one of the most abundant phyllosilicates present at the surface of Mars, under simulated martian surface ultraviolet light (190-400 nm), mean temperature (218 ± 2 K), and pressure (6 ± 1 mbar) in a laboratory simulation setup. We tested organic-rich samples that were representative of the evaporation of a small, warm pond of liquid water containing a high concentration of organics. For each molecule, we observed how the nontronite influences its quantum efficiency of photodecomposition and the nature of its solid evolution products. The results reveal a pronounced photoprotective effect of nontronite on the evolution of glycine and adenine; their efficiencies of photodecomposition were reduced by a factor of 5 when mixed at a concentration of 2.6 × 10(-2) mol of molecules per gram of nontronite. Moreover, when the amount of nontronite in the sample of glycine was increased by a factor of 2, the gain of photoprotection was multiplied by a factor of 5. This indicates that the photoprotection provided by the nontronite is not a purely mechanical shielding effect but is also due to stabilizing interactions. No new evolution product was firmly identified, but the results obtained with urea suggest a particular reactivity in the presence of nontronite, leading to an increase of its dissociation rate.

  10. Infrared active thermography for surface layer characterization

    International Nuclear Information System (INIS)

    Semerok, A.; Fomichev, S.; Farcage, D.; Sortais, C.; Courtois, X.

    2006-05-01

    Deposited layer characterization was stated as the main goal of our studies for 2006. The investigations by DRFC/SIPP/GCFP (CEA Cadarache) were performed with the procedure of surface temperature measurements based on infrared thermography with synchronous demodulation (Lock-in Thermography). It was applied to provide the temperature surface monitoring during the modulated heating by illumination. The obtained 2D-cartography revealed the zones with a weak heat transfer resulting from a low layer/surface adhesion or poor layer thermal conductivity. The obtained lock-in cartography data should be regarded only as qualitative. For deposited layers characterization (layer depth, adhesion with the substrate), the active laser pyrometer measurements with the developed experimental device were made in LILM laboratory (CEA Saclay). Active surface pyrometry with repetitive laser heating can provide both qualitative and quantitative data on the first layer and the interface with the substrate. A 3D-numerical model of graphite deposited layer heating by a pulsed high repetition rate laser beam was developed to determine the heated surface temperature with a high temporal and spatial resolution. The theoretical data obtained with 3D-numerical model for surface heating were compared with the experimental results. It was demonstrated that for the given optical and thermo-physical parameters of materials, the theoretical temperatures may be fitted with the experimental results to assess certain unknown parameters of the layer (thermal contact resistance, diffusivity, thickness, porosity, ). Based on the comparison of the obtained experimental and theoretical results, the deposited layer characterization was made. The results of the investigations on Active Laser Pyrometry and Lock-in Thermography demonstrated that the methods can provide qualitative and quantitative data on the deposited layer and on the layer/substrate interface. The correlation and cross-check of the results

  11. Adsorption of acetyl halide molecules on the surface of pristine and Al-doped graphene: Ab initio study

    Energy Technology Data Exchange (ETDEWEB)

    Rad, Ali Shokuhi, E-mail: a.shokuhi@gmail.com [Department of Chemical Engineering, Qaemshahr Branch, Islamic Azad University, Qaemshahr (Iran, Islamic Republic of); Kashani, Omid Razaghi [Department of Polymer Engineering, Qaemshahr Branch, Islamic Azad University, Qaemshahr (Iran, Islamic Republic of)

    2015-11-15

    Graphical abstract: - Highlights: • The adsorption of acetyl chloride and acetyl fluoride on Al-doped graphene were investigated. • The doped Al induces some changes in the electronic structure of graphene. • Notable orbital hybridizations are achieved upon adsorption. • Al-doped graphene can be used as a superior sensor for Acetyl halides. - Abstract: We have scrutinized the adsorption energy, electronic structure, natural bond analysis (NBO), density of state (DOS) and global indices for adsorption of acetyl chloride (AC) and acetyl fluoride (AF) on the surface of pristine graphene as well as Al-doped graphene. The adsorption energies have been calculated for the most stable configurations of the molecules on the surface of pristine and Al-doped graphene. According to the calculated parameters, there is very weak physical adsorption of AC and AF on pristine graphene while strong adsorption takes place in the case of Al-doped graphene. The charge transfer from adsorbed molecules to Al-doped graphene surface was confirmed by the natural bond orbital as well as the Mulliken population analysis while there is no charge transfer with pristine graphene. Additionally, the density of states results reveal that orbital hybridization takes place between above-mentioned molecules and Al-doped graphene sheet, whereas there is no hybridization between the molecules and the pristine graphene. Our calculated adsorption energies for the most stable position configurations of AC and AF on Al-doped graphene were −68.8 kJ mol{sup −1} (−52.6 kJ mol{sup −1} BSSE corrected energy) and −78.4 kJ mol{sup −1} (−64.3 kJ mol{sup −1} BSSE corrected energy) which are correspond to chemisorptions process respectively. These results point to the appropriateness of Al-doped graphene as a powerful adsorbent for practical applications.

  12. Single Molecule and Nanoparticle Imaging in Biophysical, Surface, and Photocatalysis Studies

    Energy Technology Data Exchange (ETDEWEB)

    Ha, Ji Won [Iowa State Univ., Ames, IA (United States)

    2013-01-01

    A differential interference contrast (DIC) polarization anisotropy is reported that was successfully used for rotational tracking of gold nanorods attached onto a kinesin-driven microtubule. A dual-wavelength detection of single gold nanorods rotating on a live cell membrane is described. Both transverse and longitudinal surface plasmon resonance (SPR) modes were used for tracking the rotational motions during a fast dynamic process under a DIC microscope. A novel method is presented to determine the full three-dimensional (3D) orientation of single plasmonic gold nanorods rotating on live cell membranes by combining DIC polarization anisotropy with an image pattern recognition technique. Polarization- and wavelength-sensitive DIC microscopy imaging of 2- m long gold nanowires as optical probes in biological studies is reported. A new method is demonstrated to track 3D orientation of single gold nanorods supported on a gold film without angular degeneracy. The idea is to use the interaction (or coupling) of gold nanorods with gold film, yielding characteristic scattering patterns such as a doughnut shape. Imaging of photocatalytic activity, polarity and selectivity on single Au-CdS hybrid nanocatalysts using a high-resolution superlocalization fluorescence imaging technique is described.

  13. Electronic and magnetic properties of Mn{sub 12} single-molecule magnets on the Au(111) surface

    Energy Technology Data Exchange (ETDEWEB)

    Voss, Soenke; Burgert, Michael; Fonin, Mikhail; Groth, Ulrich; Ruediger, Ulrich [Universitaet Konstanz (Germany); Michaelis, Christian; Brihuega, Ivan; Kern, Klaus [Max-Planck-Institut fuer Festkoerperforschung, Stuttgart (Germany); Dedkov, Yury S. [Institut fuer Festkoerperphysik, Technische Universitaet Dresden (Germany)

    2008-07-01

    The paramount interest in single-molecule magnets (SMMs) like Mn{sub 12}-acetate and its derivatives was inspired by numerous experimental and theoretical insights indicating the feasibility of addressing quantum effects of magnetism on a molecular scale. Due to its relatively high blocking temperature ({proportional_to}3 K) combined with the ability to identify well-defined spin states, Mn{sub 12} still remains the most favoured SMM possibly allowing the detection of magnetic fingerprints in transport properties of a single molecule. In this work, the electronic properties of Mn{sub 12} molecules chemically grafted on Au(111) surfaces have been studied by means of low temperature as well as room temperature scanning tunneling microscopy and spectroscopy (STS), X-ray absorption spectroscopy and photoelectron spectroscopy. The results revealed signatures from most probably intact Mn{sub 12} molecules while STS measurements in magnetic fields indicate the possibility to identify magnetic fingerprints in scanning tunneling spectra. The results will be discussed with respect to previous attempts to perform transport measurements on Mn{sub 12} SMMs.

  14. A small-molecule activator of kinesin-1 drives remodeling of the microtubule network.

    Science.gov (United States)

    Randall, Thomas S; Yip, Yan Y; Wallock-Richards, Daynea J; Pfisterer, Karin; Sanger, Anneri; Ficek, Weronika; Steiner, Roberto A; Beavil, Andrew J; Parsons, Maddy; Dodding, Mark P

    2017-12-26

    The microtubule motor kinesin-1 interacts via its cargo-binding domain with both microtubules and organelles, and hence plays an important role in controlling organelle transport and microtubule dynamics. In the absence of cargo, kinesin-1 is found in an autoinhibited conformation. The molecular basis of how cargo engagement affects the balance between kinesin-1's active and inactive conformations and roles in microtubule dynamics and organelle transport is not well understood. Here we describe the discovery of kinesore, a small molecule that in vitro inhibits kinesin-1 interactions with short linear peptide motifs found in organelle-specific cargo adaptors, yet activates kinesin-1's function of controlling microtubule dynamics in cells, demonstrating that these functions are mechanistically coupled. We establish a proof-of-concept that a microtubule motor-cargo interface and associated autoregulatory mechanism can be manipulated using a small molecule, and define a target for the modulation of microtubule dynamics.

  15. Theoretical Analysis of the Relative Significance of Thermodynamic and Kinetic Dispersion in the dc and ac Voltammetry of Surface-Confined Molecules

    KAUST Repository

    Morris, Graham P.

    2015-05-05

    © 2015 American Chemical Society. Commonly, significant discrepancies are reported in theoretical and experimental comparisons of dc voltammograms derived from a monolayer or close to monolayer coverage of redox-active surface-confined molecules. For example, broader-than-predicted voltammetric wave shapes are attributed to the thermodynamic or kinetic dispersion derived from distributions in reversible potentials (E0) and electrode kinetics (k0), respectively. The recent availability of experimentally estimated distributions of E0 and k0 values derived from the analysis of data for small numbers of surface-confined modified azurin metalloprotein molecules now allows more realistic modeling to be undertaken, assuming the same distributions apply under conditions of high surface coverage relevant to voltammetric experiments. In this work, modeling based on conventional and stochastic kinetic theory is considered, and the computationally far more efficient conventional model is shown to be equivalent to the stochastic one when large numbers of molecules are present. Perhaps unexpectedly, when experimentally determined distributions of E0 and k0 are input into the model, thermodynamic dispersion is found to be unimportant and only kinetic dispersion contributes significantly to the broadening of dc voltammograms. Simulations of ac voltammetric experiments lead to the conclusion that the ac method, particularly when the analysis of kinetically very sensitive higher-order harmonics is undertaken, are far more sensitive to kinetic dispersion than the dc method. ac methods are therefore concluded to provide a potentially superior strategy for addressing the inverse problem of determining the k0 distribution that could give rise to the apparent anomalies in surface-confined voltammetry.

  16. Identification of small-molecule antagonists that inhibit an activator: coactivator interaction.

    Science.gov (United States)

    Best, Jennifer L; Amezcua, Carlos A; Mayr, Bernhard; Flechner, Lawrence; Murawsky, Christopher M; Emerson, Beverly; Zor, Tsaffrir; Gardner, Kevin H; Montminy, Marc

    2004-12-21

    Phosphorylation of the cAMP response element binding protein (CREB) at Ser-133 in response to hormonal stimuli triggers cellular gene expression via the recruitment of the histone acetylase coactivator paralogs CREB binding protein (CBP) and p300 to the promoter. The NMR structure of the CREB:CBP complex, using relevant interaction domains called KID and KIX, respectively, reveals a shallow hydrophobic groove on the surface of KIX that accommodates an amphipathic helix in phospho (Ser-133) KID. Using an NMR-based screening approach on a preselected small-molecule library, we identified several compounds that bind to different surfaces on KIX. One of these, KG-501 (2-naphthol-AS-E-phosphate), targeted a surface distal to the CREB binding groove that includes Arg-600, a residue that is required for the CREB:CBP interaction. When added to live cells, KG-501 disrupted the CREB: CBP complex and attenuated target gene induction in response to cAMP agonist. These results demonstrate the ability of small molecules to interfere with second-messenger signaling cascades by inhibiting specific protein-protein interactions in the nucleus.

  17. Identification of intrinsic catalytic activity for electrochemical reduction of water molecules to generate hydrogen

    KAUST Repository

    Shinagawa, Tatsuya

    2015-01-01

    Insufficient hydronium ion activities at near-neutral pH and under unbuffered conditions induce diffusion-limited currents for hydrogen evolution, followed by a reaction with water molecules to generate hydrogen at elevated potentials. The observed constant current behaviors at near neutral pH reflect the intrinsic electrocatalytic reactivity of the metal electrodes for water reduction. This journal is © the Owner Societies.

  18. Rabies virus expressing dendritic cell-activating molecules enhances the innate and adaptive immune response to vaccination.

    Science.gov (United States)

    Wen, Yongjun; Wang, Hualei; Wu, Hua; Yang, Fuhe; Tripp, Ralph A; Hogan, Robert J; Fu, Zhen F

    2011-02-01

    Our previous studies indicated that recruitment and/or activation of dendritic cells (DCs) is important in enhancing the protective immune responses against rabies virus (RABV) (L. Zhao, H. Toriumi, H. Wang, Y. Kuang, X. Guo, K. Morimoto, and Z. F. Fu, J. Virol. 84:9642-9648). To address the importance of DC activation for RABV vaccine efficacy, the genes for several DC recruitment and/or activation molecules, e.g., granulocyte-macrophage colony-stimulating factor (GM-CSF), macrophage-derived chemokine (MDC), and macrophage inflammatory protein 1α (MIP-1α), were individually cloned into RABV. The ability of these recombinant viruses to activate DCs was determined in vitro and in vivo. Infection of mouse bone marrow-derived DCs with each of the recombinant viruses resulted in DC activation, as shown by increased surface expression of CD11c and CD86 as well as an increased level of alpha interferon (IFN-α) production compared to levels observed after infection with the parent virus. Intramuscular infection of mice with each of the viruses recruited and/or activated more DCs and B cells in the periphery than infection with the parent virus, leading to the production of higher levels of virus-neutralizing antibodies. Furthermore, a single immunization with recombinant RABV expressing GM-CSF or MDC protected significantly more mice against intracerebral challenge with virulent RABV than did immunization with the parental virus. Yet, these viruses did not show more virulence than the parent virus, since direct intracerebral inoculation with each virus at up to 1 × 10(7) fluorescent focus units each did not induce any overt clinic symptom, such as abnormal behavior, or any neurological signs. Together, these data indicate that recombinant RABVs expressing these molecules activate/recruit DCs and enhance protective immune responses.

  19. A new multiplexing single molecule technique for measuring restriction enzyme activity

    Science.gov (United States)

    Harbottle, Allison; Cavanaugh, Jillian; Gordon, Wendy; Loparo, Joseph; Price, Allen

    2012-02-01

    We present a new multiplexing single molecule method for observing the cleavage of DNAs by restriction enzymes. DNAs are attached to a surface at one end using a biotin-streptavidin link and to a micro bead at the other end via a digoxigenin-antidigoxigenin link. The DNAs are stretched by applying a flow. After introduction of the restriction enzyme, the exact time of cleavage of individual DNAs is recorded with video microscopy. We can image hundreds to thousands of DNAs in a single experiment. We are using our technique to search for the signature of facilitated diffusion in the measured rate dependence on ionic strength.

  20. Supported gold catalysis: from small molecule activation to green chemical synthesis.

    Science.gov (United States)

    Liu, Xiang; He, Lin; Liu, Yong-Mei; Cao, Yong

    2014-03-18

    With diminishing natural resources, there is an ever-increasing demand for cost-effective and sustainable production of fine and commodity chemicals. For this purpose, there is a need for new catalytic methods that can permit efficient and targeted conversion of fossil and biorenewable feedstocks with lower energy requirements and environmental impact. A significant number of industrial catalytic processes are performed by platinum-group-metal (PGM)-based heterogeneous catalysts capable of activating a range of important small molecules, such as CO, O2, H2, and N2. In contrast, there is a general feeling that gold (Au) cannot act as an efficient catalyst because of its inability to activate most molecules, which is essential to any catalytic processes. As a consequence, researchers have long neglected the potential for use of gold as a catalyst. In recent years, however, chemists have put forth tremendous effort and progress in the use of supported gold catalysts to facilitate a variety of useful synthetic transformations. The seminal discovery by Haruta in 1987 that suitably prepared Au-based catalysts were surprisingly active for CO oxidation even at 200 K initiated rapid development of the field. Since then, researchers have widely employed Au-based catalysts in many types of mild chemical processes, with special focus on selective reactions involving small molecules (for example, CO, H2O, O2, or H2) as a reactant. That gold in the form of tiny nanoparticles (NPs, generally less than 5 nm in diameter) can subtly activate the reactant molecules under mild conditions has been evoked to explain the superior effectiveness of gold compared with conventional PGMs. In this context, Au-based catalysts are gaining great significance in developing new green processes with improved selectivity and energy minimization. In this Account, we describe our efforts toward the development of a range of green and selective processes largely through the appropriate choice of Au

  1. Bayesian optimization for constructing potential energy surfaces of polyatomic molecules with the smallest number of ab initio calculations

    Science.gov (United States)

    Vargas-Hernandez, Rodrigo A.; v Krems, Roman

    2017-04-01

    We examine the application of kernel methods of machine learning for constructing potential energy surfaces (PES) of polyatomic molecules. In particular, we illustrate the application of Bayesian optimization with Gaussian processes as an efficient method for sampling the configuration space of polyatomic molecules. Bayesian optimization relies on two key components: a prior over an objective function and a mechanism for sampling the configuration space. We use Gaussian processes to model the objective function and various acquisition functions commonly used in computer science to quantify the accuracy of sampling. The PES is obtained through an iterative process of adding ab initio points at the locations maximizing the acquisition function and re-trainig the Gaussian process with new points added. We sample different PESs with one or many acquisition functions and show how the acquisition functions affect the construction of the PESs.

  2. Ab initio molecular dynamics calculations on reactions of molecules with metal surfaces

    NARCIS (Netherlands)

    Nattino, Francesco

    2015-01-01

    Reactions on metal surfaces are of scientific interest due to the tremendous relevance of heterogeneous catalysis. Single crystal surfaces under controlled physical conditions are generally employed as a model for the real catalysts, with the aim of improving the fundamental understanding of the

  3. Early-Late Heterobimetallic Complexes Linked by Phosphinoamide Ligands. Tuning Redox Potentials and Small Molecule Activation

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, Christine M. [Brandeis Univ., Waltham, MA (United States)

    2015-08-01

    Recent attention in the chemical community has been focused on the energy efficient and environmentally benign conversion of abundant small molecules (CO2, H2O, etc.) to useful liquid fuels. This project addresses these goals by examining fundamental aspects of catalyst design to ultimately access small molecule activation processes under mild conditions. Specifically, Thomas and coworkers have targetted heterobimetallic complexes that feature metal centers with vastly different electronic properties, dictated both by their respective positions on the periodic table and their coordination environment. Unlike homobimetallic complexes featuring identical or similar metals, the bonds between metals in early/late heterobimetallics are more polarized, with the more electron-rich late metal center donating electron density to the more electron-deficient early metal center. While metal-metal bonds pose an interesting strategy for storing redox equivalents and stabilizing reactive metal fragments, the polar character of metal-metal bonds in heterobimetallic complexes renders these molecules ideally poised to react with small molecule substrates via cleavage of energy-rich single and double bonds. In addition, metal-metal interactions have been shown to dramatically affect redox potentials and promote multielectron redox activity, suggesting that metal-metal interactions may provide a mechanism to tune redox potentials and access substrate reduction/activation at mild overpotentials. This research project has provided a better fundamental understanding of how interactions between transition metals can be used as a strategy to promote and/or control chemical transformations related to the clean production of fuels. While this project focused on the study of homogeneous systems, it is anticipated that the broad conclusions drawn from these investigations will be applicable to heterogeneous catalysis as well, particularly on heterogeneous processes that occur at interfaces in

  4. Homochirality in space – Selective enrichment of chiral molecules on chiral surfaces

    Directory of Open Access Journals (Sweden)

    Marloie G.

    2014-02-01

    $\\left\\{ {10\\,\\overline {10} } \\right\\}$ and the chiral molécule is lactic acid, HOCH(CH3COOH. In this theoretical work we rely on numerical simulations based on Density Functional Theory (DFT that proved efficient in the super-molecule and periodic approaches to this category of phenomena. In view of the different types of adsorption sites, a statistical treatment was necessary; it shows that (S-lactic acid is preferentially adsorbed with a selectivity of ~0.7 kcal/mol with respect to the (R isomer.

  5. Topoisomerase I as a Biomarker: Detection of Activity at the Single Molecule Level

    DEFF Research Database (Denmark)

    Proszek, Joanna; Roy, Amit; Jakobsen, Ann-Katrine

    2014-01-01

    of hTopI cleavage-religation activity at the single molecule level, may be used to detect posttranslational enzymatic differences influencing CPT response. These differences cannot be detected by analysis of hTopI gene copy number, mRNA amount, or protein amount, and only become apparent upon measuring......Human topoisomerase I (hTopI) is an essential cellular enzyme. The enzyme is often upregulated in cancer cells, and it is a target for chemotherapeutic drugs of the camptothecin (CPT) family. Response to CPT-based treatment is dependent on hTopI activity, and reduction in activity, and mutations...... in hTopI have been reported to result in CPT resistance. Therefore, hTOPI gene copy number, mRNA level, protein amount, and enzyme activity have been studied to explain differences in cellular response to CPT. We show that Rolling Circle Enhanced Enzyme Activity Detection (REEAD), allowing measurement...

  6. Theoretical investigation of the degradation mechanisms in host and guest molecules used in OLED active layers

    KAUST Repository

    Winget, Paul

    2014-10-08

    A feature of OLEDs that has to date received little attention is the prediction of the stability of the molecules involved in the electrical and optical processes. Here, we present computational results intended to aid in the development of stable systems. We identify degradation pathways and define new strategies to guide the synthesis of stable materials for OLED applications for both phosphorescent emitters and organic host materials. The chemical reactivity of these molecules in the active layers of the devices is further complicated by the fact that, during operation, they can be either oxidized or reduced (as they localize a hole or an electron) in addition to forming both singlet and triplet excitons. © (2014) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.

  7. Generation of murine tumor cell lines deficient in MHC molecule surface expression using the CRISPR/Cas9 system.

    Science.gov (United States)

    Das, Krishna; Eisel, David; Lenkl, Clarissa; Goyal, Ashish; Diederichs, Sven; Dickes, Elke; Osen, Wolfram; Eichmüller, Stefan B

    2017-01-01

    In this study, the CRISPR/Cas9 technology was used to establish murine tumor cell lines, devoid of MHC I or MHC II surface expression, respectively. The melanoma cell line B16F10 and the murine breast cancer cell line EO-771, the latter stably expressing the tumor antigen NY-BR-1 (EO-NY), were transfected with an expression plasmid encoding a β2m-specific single guide (sg)RNA and Cas9. The resulting MHC I negative cells were sorted by flow cytometry to obtain single cell clones, and loss of susceptibility of peptide pulsed MHC I negative clones to peptide-specific CTL recognition was determined by IFNγ ELISpot assay. The β2m knockout (KO) clones did not give rise to tumors in syngeneic mice (C57BL/6N), unless NK cells were depleted, suggesting that outgrowth of the β2m KO cell lines was controlled by NK cells. Using sgRNAs targeting the β-chain encoding locus of the IAb molecule we also generated several B16F10 MHC II KO clones. Peptide loaded B16F10 MHC II KO cells were insusceptible to recognition by OT-II cells and tumor growth was unaltered compared to parental B16F10 cells. Thus, in our hands the CRISPR/Cas9 system has proven to be an efficient straight forward strategy for the generation of MHC knockout cell lines. Such cell lines could serve as parental cells for co-transfection of compatible HLA alleles together with human tumor antigens of interest, thereby facilitating the generation of HLA matched transplantable tumor models, e.g. in HLAtg mouse strains of the newer generation, lacking cell surface expression of endogenous H2 molecules. In addition, our tumor cell lines established might offer a useful tool to investigate tumor reactive T cell responses that function independently from MHC molecule surface expression by the tumor.

  8. Generation of murine tumor cell lines deficient in MHC molecule surface expression using the CRISPR/Cas9 system.

    Directory of Open Access Journals (Sweden)

    Krishna Das

    Full Text Available In this study, the CRISPR/Cas9 technology was used to establish murine tumor cell lines, devoid of MHC I or MHC II surface expression, respectively. The melanoma cell line B16F10 and the murine breast cancer cell line EO-771, the latter stably expressing the tumor antigen NY-BR-1 (EO-NY, were transfected with an expression plasmid encoding a β2m-specific single guide (sgRNA and Cas9. The resulting MHC I negative cells were sorted by flow cytometry to obtain single cell clones, and loss of susceptibility of peptide pulsed MHC I negative clones to peptide-specific CTL recognition was determined by IFNγ ELISpot assay. The β2m knockout (KO clones did not give rise to tumors in syngeneic mice (C57BL/6N, unless NK cells were depleted, suggesting that outgrowth of the β2m KO cell lines was controlled by NK cells. Using sgRNAs targeting the β-chain encoding locus of the IAb molecule we also generated several B16F10 MHC II KO clones. Peptide loaded B16F10 MHC II KO cells were insusceptible to recognition by OT-II cells and tumor growth was unaltered compared to parental B16F10 cells. Thus, in our hands the CRISPR/Cas9 system has proven to be an efficient straight forward strategy for the generation of MHC knockout cell lines. Such cell lines could serve as parental cells for co-transfection of compatible HLA alleles together with human tumor antigens of interest, thereby facilitating the generation of HLA matched transplantable tumor models, e.g. in HLAtg mouse strains of the newer generation, lacking cell surface expression of endogenous H2 molecules. In addition, our tumor cell lines established might offer a useful tool to investigate tumor reactive T cell responses that function independently from MHC molecule surface expression by the tumor.

  9. Structure-activity relationship studies of indole-based compounds as small molecule HIV-1 fusion inhibitors targeting glycoprotein 41.

    Science.gov (United States)

    Zhou, Guangyan; Sofiyev, Vladimir; Kaur, Hardeep; Snyder, Beth A; Mankowski, Marie K; Hogan, Priscilla A; Ptak, Roger G; Gochin, Miriam

    2014-06-26

    We previously described indole-containing compounds with the potential to inhibit HIV-1 fusion by targeting the hydrophobic pocket of transmembrane glycoprotein gp41. Here we report optimization and structure-activity relationship studies on the basic scaffold, defining the role of shape, contact surface area, and molecular properties. Thirty new compounds were evaluated in binding, cell-cell fusion, and viral replication assays. Below a 1 μM threshold, correlation between binding and biological activity was diminished, indicating an amphipathic requirement for activity in cells. The most active inhibitor 6j exhibited 0.6 μM binding affinity and 0.2 μM EC50 against cell-cell fusion and live virus replication and was active against T20 resistant strains. Twenty-two compounds with the same connectivity displayed a consensus pose in docking calculations, with rank order matching the biological activity. The work provides insight into requirements for small molecule inhibition of HIV-1 fusion and demonstrates a potent low molecular weight fusion inhibitor.

  10. Structure–Activity Relationship Studies of Indole-Based Compounds as Small Molecule HIV-1 Fusion Inhibitors Targeting Glycoprotein 41

    Science.gov (United States)

    2015-01-01

    We previously described indole-containing compounds with the potential to inhibit HIV-1 fusion by targeting the hydrophobic pocket of transmembrane glycoprotein gp41. Here we report optimization and structure–activity relationship studies on the basic scaffold, defining the role of shape, contact surface area, and molecular properties. Thirty new compounds were evaluated in binding, cell–cell fusion, and viral replication assays. Below a 1 μM threshold, correlation between binding and biological activity was diminished, indicating an amphipathic requirement for activity in cells. The most active inhibitor 6j exhibited 0.6 μM binding affinity and 0.2 μM EC50 against cell–cell fusion and live virus replication and was active against T20 resistant strains. Twenty-two compounds with the same connectivity displayed a consensus pose in docking calculations, with rank order matching the biological activity. The work provides insight into requirements for small molecule inhibition of HIV-1 fusion and demonstrates a potent low molecular weight fusion inhibitor. PMID:24856833

  11. Intense Visible Luminescence in CdSe Quantum Dots by Efficiency Surface Passivation with H2O Molecules

    Directory of Open Access Journals (Sweden)

    Hyeoung Woo Park

    2012-01-01

    Full Text Available We have investigated the effect of water (H2O cooling and heat treatment on the luminescence efficiency of core CdSe quantum dots (QDs. The photoluminescence (PL quantum yield of the CdSe QDs was enhanced up to ~85%, and some periodic bright points were observed in wide color ranges during the heat treatment of QDs mixed with H2O. The PL enhancement of QDs could be attributed to the recovery of QDs surface traps by unreacted ligands confined within the hydrophilic H2O molecule containers.

  12. MO LCAO approximation in solid state approach for calculations of electronic structure of a crystal surface and chemisorbed molecule

    International Nuclear Information System (INIS)

    Tapilin, V.M.

    1982-01-01

    A scheme of calculation of the electronic structure of a solid state surface and chemisorbed molecules is discussed. The method of the Green's function and MO LCAO approximation are used which permits to perform calculations, taking into account the whole crystal but not its fragment only, with the accuracy adopted by quantum chemistry. Results of model calculations are presented: chemisorption of hydrogen-like atom on the (100) face of the one-band crystal model and dispersion curves for the density of states of nickel (100) face. (Auth.)

  13. 3D nanostar dimers with a sub-10-nm gap for single-/few-molecule surface-enhanced raman scattering

    KAUST Repository

    Chirumamilla, Manohar

    2014-01-22

    Plasmonic nanostar-dimers, decoupled from the substrate, have been fabricated by combining electron-beam lithography and reactive-ion etching techniques. The 3D architecture, the sharp tips of the nanostars and the sub-10 nm gap size promote the formation of giant electric-field in highly localized hot-spots. The single/few molecule detection capability of the 3D nanostar-dimers has been demonstrated by Surface-Enhanced Raman Scattering. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Virus-based surface patterning of biological molecules, probes, and inorganic materials.

    Science.gov (United States)

    Ahn, Suji; Jeon, Seongho; Kwak, Eun-A; Kim, Jong-Man; Jaworski, Justyn

    2014-10-01

    An essential requirement for continued technological advancement in many areas of biology, physics, chemistry, and materials science is the growing need to generate custom patterned materials. Building from recent achievements in the site-specific modification of virus for covalent surface tethering, we show in this work that stable 2D virus patterns can be generated in custom geometries over large area glass surfaces to yield templates of biological, biochemical, and inorganic materials in high density. As a nanomaterial building block, filamentous viruses have been extensively used in recent years to produce materials with interesting properties, owing to their ease of genetic and chemical modification. By utilizing un-natural amino acids generated at specific locations on the filamentous fd bacteriophage protein coat, surface immobilization is carried out on APTES patterned glass resulting in precise geometries of covalently linked virus material. This technique facilitated the surface display of a high density of virus that were labeled with biomolecules, fluorescent probes, and gold nanoparticles, thereby opening the possibility of integrating virus as functional components for surface engineering. Copyright © 2014 Elsevier B.V. All rights reserved.

  15. Manipulating Magnetism at Organic/Ferromagnetic Interfaces by Molecule-Induced Surface Reconstruction.

    Science.gov (United States)

    Pang, Rui; Shi, Xingqiang; Van Hove, Michel A

    2016-03-30

    Fullerenes have several advantages as potential materials for organic spintronics. Through a theoretical first-principles study, we report that fullerene C60 adsorption can induce a magnetic reconstruction in a Ni(111) surface and expose the merits of the reconstructed C60/Ni(111) spinterface for molecular spintronics applications. Surface reconstruction drastically modifies the magnetic properties at both sides of the C60/Ni interface. Three outstanding properties of the reconstructed structure are revealed, which originate from reconstruction enhanced spin-split π-d coupling between C60 and Ni(111): (1) the C60 spin polarization and conductance around the Fermi level are enhanced simultaneously, which can be important for read-head sensor miniaturization; (2) localized spin-polarized states appear in C60 with a spin-filter functionality; and (3) magnetocrystalline anisotropic energy and exchange coupling in the outermost Ni layer are reduced enormously. Surface reconstruction can be realized simply by controlling the annealing temperature in experiments.

  16. Determination of surface concentrations of individual molecule-layers used in nanoscale biosensors by in situ ATR-FTIR spectroscopy

    KAUST Repository

    Punzet, Manuel

    2012-01-01

    For the development of nanowire sensors for chemical and medical detection purposes, the optimal functionalization of the surface is a mandatory component. Quantitative ATR-FTIR spectroscopy was used in situ to investigate the step-by-step layer formation of typical functionalization protocols and to determine the respective molecule surface concentrations. BSA, anti-TNF-α and anti-PSA antibodies were bound via 3-(trimethoxy)butylsilyl aldehyde linkers to silicon-oxide surfaces in order to investigate surface functionalization of nanowires. Maximum determined surface concentrations were 7.17 × 10 -13 mol cm -2 for BSA, 1.7 × 10 -13 mol cm -2 for anti-TNF-α antibody, 6.1 × 10 -13 mol cm -2 for anti-PSA antibody, 3.88 × 10 -13 mol cm -2 for TNF-α and 7.0 × 10 -13 mol cm -2 for PSA. Furthermore we performed antibody-antigen binding experiments and determined the specific binding ratios. The maximum possible ratio of 2 was obtained at bulk concentrations of the antigen in the μg ml -1 range for TNF-α and PSA. © 2012 The Royal Society of Chemistry.

  17. Interaction of an immunodominant epitope with Ia molecules in T-cell activation

    DEFF Research Database (Denmark)

    Adorini, L; Sette, A; Buus, S

    1988-01-01

    The amino acid sequence corresponding to residues 107-116 of hen egg-white lysozyme (HEL) has been identified as containing an immunodominant T-cell epitope recognized in association with the I-Ed molecule. The immunodominance of this epitope in HEL-primed H-2d mice was demonstrated by analysis...... of the T-cell proliferative response induced by synthetic peptides covering almost the entire HEL sequence. All the T-cell hybridomas from H-2d mice analyzed recognize the HEL sequence 107-116 in association with the I-Ed molecule. Correlating with the restriction of T-cell recognition, HEL-(105......-120)-peptide binds to I-Ed but not to I-Ad molecules. Conservative or semiconservative substitutions at positions 113 (Asn----Lys), 114 (Arg----His), or 115 (Cys----Ala) abrogate the ability of HEL-(105-120) to activate T cells. Substitutions at residues 113 and 115 affect T-cell recognition...

  18. Electrochemistry of Single Metalloprotein and DNA‐Based Molecules at Au(111) Electrode Surfaces

    DEFF Research Database (Denmark)

    Salvatore, Princia; Zeng, Dongdong; Karlsen, Kasper Kannegård

    2013-01-01

    have been primary targets, with a view on stabilizing the ds‐ONs and improving voltammetric signals of intercalating electrochemical redox probes. Voltammetric signals of the intercalator anthraquinone monosulfonate (AQMS) at ds‐DNA/Au(111) surfaces diluted by mercaptohexanol are significantly...

  19. Performance of a Microfluidic Device for In Situ ToF-SIMS Analysis of Selected Organic Molecules at Aqueous Surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Li; Zhu, Zihua; Yu, Xiao-Ying; Thevuthasan, Suntharampillai; Cowin, James P.

    2013-04-03

    Time-of-flight secondary ion mass spectrometry (ToF-SIMS) is a unique surface analysis technique because it can provide molecular recognition for organic and biological molecules. However, analyzing aqueous solution surfaces by ToF-SIMS is difficult, because ToF-SIMS is a high-vacuum technique, while the vapor pressure of water is about 2.3 kPa at room temperature (20 C). We designed and fabricated a self-contained microfluidic device, enabling in situ analysis of aqueous surfaces by scanning electron microscope (SEM) and ToF-SIMS, which has been briefly reported.1,2 In this study, we report more performance data, focusing on the performance of this device for in situ analysis of organic molecules at aqueous surfaces using ToF-SIMS. Three representative organic compounds (formic acid, glycerol, and glutamic acid) were tested, and their molecular signals were successfully observed. The device can be self-running in vacuum for 8 hours, and SIMS measurements are feasible at any time in this time range. The stability of this device under primary ion beam bombardment is also impressive. High fluence (6 × 1012 ions cm-2 s-1) measurements can be operated continuously for up to 30 minutes without any significant damage to the aperture. However, extra-high fluence measurements (>1 × 1014 ions cm-2 s-1) may lead to liquid bumping in the aperture, and the aqueous solutions may spread out quickly. Signal reproducibility is reasonably good, and relative standard deviation (RSD) for molecular ion signals can be controlled to be smaller than ±15% for consecutive measurements. Measurements at long time intervals (e.g., 60 min) show RSDs of ±40-50%. In addition, the detection limits of formic acid, glycerol, and glutamic acid are estimated to be 0.04%, 0.008%, and 0.002% (weight ratio), respectively.

  20. In vitro and in vivo activity of a novel antifungal small molecule against Candida infections.

    Directory of Open Access Journals (Sweden)

    Sarah Sze Wah Wong

    Full Text Available Candida is the most common fungal pathogen of humans worldwide and has become a major clinical problem because of the growing number of immunocompromised patients, who are susceptible to infection. Moreover, the number of available antifungals is limited, and antifungal-resistant Candida strains are emerging. New and effective antifungals are therefore urgently needed. Here, we discovered a small molecule with activity against Candida spp. both in vitro and in vivo. We screened a library of 50,240 small molecules for inhibitors of yeast-to-hypha transition, a major virulence attribute of Candida albicans. This screening identified 20 active compounds. Further examination of the in vitro antifungal and anti-biofilm properties of these compounds, using a range of Candida spp., led to the discovery of SM21, a highly potent antifungal molecule (minimum inhibitory concentration (MIC 0.2-1.6 µg/ml. In vitro, SM21 was toxic to fungi but not to various human cell lines or bacterial species and was active against Candida isolates that are resistant to existing antifungal agents. Moreover, SM21 was relatively more effective against biofilms of Candida spp. than the current antifungal agents. In vivo, SM21 prevented the death of mice in a systemic candidiasis model and was also more effective than the common antifungal nystatin at reducing the extent of tongue lesions in a mouse model of oral candidiasis. Propidium iodide uptake assay showed that SM21 affected the integrity of the cell membrane. Taken together, our results indicate that SM21 has the potential to be developed as a novel antifungal agent for clinical use.

  1. MRD-CI potential surfaces using balanced basis sets. IV. The H2 molecule and the H3 surface

    International Nuclear Information System (INIS)

    Wright, J.S.; Kruus, E.

    1986-01-01

    The utility of midbond functions in molecular calculations was tested in two cases where the correct results are known: the H 2 potential curve and the collinear H 3 potential surface. For H 2 , a variety of basis sets both with and without bond functions was compared to the exact nonrelativistic potential curve of Kolos and Wolniewicz [J. Chem. Phys. 43, 2429 (1965)]. It was found that optimally balanced basis sets at two levels of quality were the double zeta single polarization plus sp bond function basis (BF1) and the triple zeta double polarization plus two sets of sp bond function basis (BF2). These gave bond dissociation energies D/sub e/ = 4.7341 and 4.7368 eV, respectively (expt. 4.7477 eV). Four basis sets were tested for basis set superposition errors, which were found to be small relative to basis set incompleteness and therefore did not affect any conclusions regarding basis set balance. Basis sets BF1 and BF2 were used to construct potential surfaces for collinear H 3 , along with the corresponding basis sets DZ*P and TZ*PP which contain no bond functions. Barrier heights of 12.52, 10.37, 10.06, and 9.96 kcal/mol were obtained for basis sets DZ*P, TZ*PP, BF1, and BF2, respectively, compared to an estimated limiting value of 9.60 kcal/mol. Difference maps, force constants, and relative rms deviations show that the bond functions improve the surface shape as well as the barrier height

  2. Ultra-stable Molecule-Surface Architectures at Metal Oxides: Structure, Bonding, and Electron-transfer Processes

    Energy Technology Data Exchange (ETDEWEB)

    Hamers, Robert John

    2013-12-07

    Research funded by this project focused on the development of improved strategies for functionalization of metal oxides to enhance charge-transfer processes relevant to solar energy conversion. Initial studies included Fe2O3, WO3, TiO2, SnO2, and ZnO as model oxide systems; these systems were chosen due to differences in metal oxidation state and chemical bonding types in these oxides. Later studies focused largely on SnO2 and ZnO, as these materials show particularly promising surface chemistry, have high electron mobility, and can be readily grown in both spherical nanoparticles and as elongated nanorods. New molecules were synthesized that allowed the direct chemical assembly of novel nanoparticle ?dyadic? structures in which two different oxide materials are chemically joined, leading to an interface that enhances the separation of of charge upon illumination. We demonstrated that such junctions enhance photocatalytic efficiency using model organic compounds. A separate effort focused on novel approaches to linking dye molecules to SnO2 and ZnO as a way to enhance solar conversion efficiency. A novel type of surface binding through

  3. Does Titan have an Active Surface?

    Science.gov (United States)

    Nelson, R.

    2009-12-01

    ammonia, a compound expected in Titan’s interior. This, combined with the previous evidence from VIMS and RADAR images, creates a strong case for Titan having a presently active surface, possibly due to cryovolcanism. Cassini encountered Titan at very close range on 2008-11-19-13:58 and again on 2008-12-05-12:38. These epochs are called T47 and T48. Comparison of earlier lower resolution data (T5) with the recent T47 and T48 data reveal changes of the surface reflectance and morphology in the Hotei region. This is the first evidence from VIMS that confirms the RADAR report that Hotei Reggio has morphology consistent with volcanic terrain. It has not escaped our attention that ammonia, in association with methane and nitrogen, the principal species of Titan’s atmosphere, closely replicates the environment at the time that live first emerged on earth. If Titan is currently active then these results raise the following questions: What is the full extent of current geologic activity? What are the ongoing processes? Are Titan’s chemical processes today supporting a prebiotic chemistry similar to that under which life evolved on Earth? This work done at JPL under contract with NASA. Refs: [1]R. M. Nelson et al., Icarus 199 (2009) 429-441. [2]R. M. Nelson et al., GRL, VOL. 36, L04202, doi:10.1029/2008GL036206, 2009. [3]S. D. Wall GRL, VOL. 36, L04203, doi:10.1029/2008GL036415, 2009

  4. Using Thermogenic Beige Cells to Identify Biologically Active Small Molecules and Peptides.

    Science.gov (United States)

    Wu, Ling; Xu, Bin

    2017-01-01

    Incorporating molecular libraries in chemical biology screenings in cultured cells has been successfully used for gene discovery in many cellular processes. It has the unique potential to uncover novel mechanisms of complex cellular biology through the screening of small molecules and protein biologics in relevant cell-based assays. Recent development in the understanding and generation of thermogenic adipocytes provides opportunities for potential anti-obesity therapeutics discovery. In this chapter, we describe screening methods using thermogenic beige cells to identify novel compounds and peptides that activate adipocyte thermogenesis.

  5. Activation of stress signaling molecules in bat brain during arousal from hibernation.

    Science.gov (United States)

    Lee, Moonyong; Choi, Inho; Park, Kyoungsook

    2002-08-01

    Induction of glucose-regulated proteins (GRPs) is a ubiquitous intracellular response to stresses such as hypoxia, glucose starvation and acidosis. The induction of GRPs offers some protection against these stresses in vitro, but the specific role of GRPs in vivo remains unclear. Hibernating bats present a good in vivo model to address this question. The bats must overcome local high oxygen demand in tissue by severe metabolic stress during arousal thermogenesis. We used brain tissue of a temperate bat Rhinolopus ferrumequinum to investigate GRP induction by high metabolic oxygen demand and to identify associated signaling molecules. We found that during 30 min of arousal, oxygen consumption increased from nearly zero to 11.9/kg/h, which was about 8.7-fold higher than its active resting metabolic rate. During this time, body temperature rose from 7 degrees C to 35 degrees C, and levels of TNF-alpha and lactate in brain tissue increased 2-2.5-fold, indicating a high risk of oxygen shortage. Concomitantly, levels of GRP75, GRP78 and GRP94 increased 1.5-1.7-fold. At the same time, c-Jun N-terminal protein kinase (JNK) activity increased 6.4-fold, and extracellular signal-regulated protein kinase (ERK) activity decreased to a similar degree (6.1-fold). p38 MAPK activity was very low and remained unchanged during arousal. In addition, survival signaling molecules protein kinase B (Akt) and protein kinase C (PKC) were activated 3- and 5-fold, respectively, during arousal. Taken together, our results showed that bat brain undergoes high oxygen demand during arousal from hibernation. Up-regulation of GRP proteins and activation of JNK, PKCgamma and Akt may be critical for neuroprotection and the survival of bats during the repeated process.

  6. Small molecule activators of SIRT1 replicate signaling pathways triggered by calorie restriction in vivo

    Directory of Open Access Journals (Sweden)

    Lavu Siva

    2009-03-01

    Full Text Available Abstract Background Calorie restriction (CR produces a number of health benefits and ameliorates diseases of aging such as type 2 diabetes. The components of the pathways downstream of CR may provide intervention points for developing therapeutics for treating diseases of aging. The NAD+-dependent protein deacetylase SIRT1 has been implicated as one of the key downstream regulators of CR in yeast, rodents, and humans. Small molecule activators of SIRT1 have been identified that exhibit efficacy in animal models of diseases typically associated with aging including type 2 diabetes. To identify molecular processes induced in the liver of mice treated with two structurally distinct SIRT1 activators, SIRT501 (formulated resveratrol and SRT1720, for three days, we utilized a systems biology approach and applied Causal Network Modeling (CNM on gene expression data to elucidate downstream effects of SIRT1 activation. Results Here we demonstrate that SIRT1 activators recapitulate many of the molecular events downstream of CR in vivo, such as enhancing mitochondrial biogenesis, improving metabolic signaling pathways, and blunting pro-inflammatory pathways in mice fed a high fat, high calorie diet. Conclusion CNM of gene expression data from mice treated with SRT501 or SRT1720 in combination with supporting in vitro and in vivo data demonstrates that SRT501 and SRT1720 produce a signaling profile that mirrors CR, improves glucose and insulin homeostasis, and acts via SIRT1 activation in vivo. Taken together these results are encouraging regarding the use of small molecule activators of SIRT1 for therapeutic intervention into type 2 diabetes, a strategy which is currently being investigated in multiple clinical trials.

  7. Design and fabrication of structural color by local surface plasmonic meta-molecules

    International Nuclear Information System (INIS)

    Ma Ya-Qi; Shao Jin-Hai; Lu Bing-Rui; Zhang Si-Chao; Chen Yi-Fang; Zhang Ya-Feng; Sun Yan; Qu Xin-Ping

    2015-01-01

    In this paper, we propose a new form of nanostructures with Al film deposited on a patterned dielectric material for generating structural color, which is induced by local surface plasmonic resonant (LSPR) absorption in sub-wavelength-indented hole/ring arrays. Unlike other reported results obtained by using focus ion beam (FIB) to create metallic nanostructures, the nano-sized hole/ring arrays in Al film in this work are replicated by high resolution electron beam lithography (EBL) combined with self-aligned metallization. Clear structural color is observed and systematically studied by numerical simulations as well as optical characterizations. The central color is strongly related to the geometric size, which provides us with good opportunities to dye the colorless Al surface by controlling the hole/ring dimensions (both diameter and radius), and to open up broad applications in display, jewelry decoration, green production of packing papers, security code, and counterfeits prevention. (paper)

  8. Virtual screening and statistical analysis in the design of new caffeine analogues molecules with potential epithelial anticancer activity.

    Science.gov (United States)

    Costa, Josivan da Silva; Costa, Karina Da Silva Lopes; Cruz, Josiane Viana; Ramosb, Ryan da Silva; Silva, Luciane Barros; Barros Brasilc, Davi Do Socorro; Henrique Tomich de Paula da Silva, Carlos; Santos, Cleydson Breno Rodrigues Dos; Macêdoe, Williams Jorge da Cruz

    2017-07-11

    About 132 thousand cases of melanoma (more severe type of skin cancer) were registered in 2014 according to the world health organization. This type of cancer significantly affects the quality of life of individuals. Caffeine has shown potential inhibitory effect against epithelial cancer. In this study, it was proposed to obtain new caffeine-based molecules with potential epithelial anticancer activity. For this, a training set of 21 molecules was used for pharmacophore perception procedures. Multiple linear regression analyses were used to propose mono-, bi-, tri-, and tetra-parametric models applied in the prediction of the activity. The generated pharmacophore was used to select 350 molecules available at the ZINCpharmer server, followed by reduction to 24 molecules, after selection using the Tanimoto index, yielding 10 molecules after final selection by predicted activity values > 1.5229. These ten molecules had better pharmacokinetic properties than the other ones used as reference and within the clinically significant limits. Only two molecules show minor hits of toxicity and were submitted to molecular docking procedures, showing BFE (binding free energy) values lower than the reference values. Statistical analyses indicated strong negative correlations between BFE and pharmacophoric properties (high influence on BFE lowering) and practically null correlation between BFE and BBB. The two most promising molecules can be indicated as candidates for further in vitro and in vivo analyzes. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  9. Surface and interface electronic structure: Three year activity report

    International Nuclear Information System (INIS)

    Kevan, S.D.

    1992-01-01

    The 3-year activity report covers surface structure and phonon anomalies (surface reconstruction on W(001) and Mo(001), adsorbate lateral ordering, surface Fermi contours and phonon anomalies on Pt(111) and Pd(001)), adsorbate vibrational damping, charge transfer in momentum space: W(011)-K, surface states and resonances (relativistic effects ampersand computations, surface resonances)

  10. Assessing the reliability of predictive activity coefficient models for molecules consisting of several functional groups

    Directory of Open Access Journals (Sweden)

    R. P. Gerber

    2013-03-01

    Full Text Available Currently, the most successful predictive models for activity coefficients are those based on functional groups such as UNIFAC. In contrast, these models require a large amount of experimental data for the determination of their parameter matrix. A more recent alternative is the models based on COSMO, for which only a small set of universal parameters must be calibrated. In this work, a recalibrated COSMO-SAC model was compared with the UNIFAC (Do model employing experimental infinite dilution activity coefficient data for 2236 non-hydrogen-bonding binary mixtures at different temperatures. As expected, UNIFAC (Do presented better overall performance, with a mean absolute error of 0.12 ln-units against 0.22 for our COSMO-SAC implementation. However, in cases involving molecules with several functional groups or when functional groups appear in an unusual way, the deviation for UNIFAC was 0.44 as opposed to 0.20 for COSMO-SAC. These results show that COSMO-SAC provides more reliable predictions for multi-functional or more complex molecules, reaffirming its future prospects.

  11. Photoelectron diffraction of C6H8/Si(001) : A model case for photoemission study of organic molecules adsorbed on silicon surfaces

    Science.gov (United States)

    Gunnella, R.; Shimomura, M.; D'Amico, F.; Abukawa, T.; Kono, S.

    2006-06-01

    The core-level photoemission of 1,4-cyclohexadiene molecules on the quasi-single-domain 2×1-Si(001) surface below the saturation condition was studied. Taking advantage of core-level-shift photoelectron diffraction of the C 1s core level, the details of the surface structure were found. The model was essentially constituted by an unbuckled (planar) molecule chemisorbed on the surface, inclined at an angle of about 18° with respect to the surface normal, keeping one double bond unsaturated. An accurate analysis of the line shape parameters of the strongly asymmetric C 1s core level was mandatory for the structural study. Conversely, the success of the structural determination represented a confirmation of the correct deconvolution procedure. Such a feedback loop was decisive in reducing the indeterminacy affecting the analysis of core-level photoemission in the case of complex molecules adsorbed on surfaces.

  12. Design and fabrication of structural color by local surface plasmonic meta-molecules

    Science.gov (United States)

    Ma, Ya-Qi; Shao, Jin-Hai; Zhang, Ya-Feng; Lu, Bing-Rui; Zhang, Si-Chao; Sun, Yan; Qu, Xin-Ping; Chen, Yi-Fang

    2015-08-01

    In this paper, we propose a new form of nanostructures with Al film deposited on a patterned dielectric material for generating structural color, which is induced by local surface plasmonic resonant (LSPR) absorption in sub-wavelength-indented hole/ring arrays. Unlike other reported results obtained by using focus ion beam (FIB) to create metallic nanostructures, the nano-sized hole/ring arrays in Al film in this work are replicated by high resolution electron beam lithography (EBL) combined with self-aligned metallization. Clear structural color is observed and systematically studied by numerical simulations as well as optical characterizations. The central color is strongly related to the geometric size, which provides us with good opportunities to dye the colorless Al surface by controlling the hole/ring dimensions (both diameter and radius), and to open up broad applications in display, jewelry decoration, green production of packing papers, security code, and counterfeits prevention. Project partially supported by the National Natural Science Foundation of China (Grant No. 61205148).

  13. Application of an efficient asymptotic analysis method to molecule-surface scattering

    Science.gov (United States)

    Mowrey, R. C.; Kroes, G. J.

    1995-07-01

    An improved method for performing asymptotic analysis developed by Balint-Kurti et al. [J. Chem. Soc. Faraday Trans. 86, 1741 (1990)] was used with the close-coupling wave packet (CCWP) method. S-matrix elements are computed from the time dependence of the wave packet amplitude at a dividing surface in the asymptotic region. The analysis technique can be combined in a natural way with the use of an optical potential to absorb the scattered wave function beyond the dividing surface and with a technique in which the initial wave function is brought in on a separate, one-dimensional grid, thereby allowing the use of a smaller grid. The use of the method in conjunction with the Chebyshev and short-iterative Lanczos propagation techniques is demonstrated for a model problem in which H2 is scattered from LiF(001). Computed S-matrix elements are in good agreement with those obtained using a time-independent close-coupling method.

  14. Influence of the crystallographic structure of the electrode surface on the structure of the electrical double layer and adsorption of organic molecules

    International Nuclear Information System (INIS)

    Kochorovski, Z.; Zagorska, I.; Pruzhkovska-Drakhal, R.; Trasatti, S.

    1995-01-01

    The results of systematic investigation of influence of crystal structure of Bi-, Sb- and Cd-electrode surfaces on regularities of double electric layer structure in aqueous and nonaqueous solutions of surface-nonactive electrolyte are given. Influence of electrode surface characteristics on adsorptive behaviour of different organic molecules has been studied. General regularities of of chemical nature influence and surface crystallographic structure on the double layer structure and on organic compounds adsorption have been established. 57 refs., 7 figs., 4 tabs

  15. Development of Small Molecule Activators of Protein Phosphotase 2A (SMAPs) for the Treatment of Castration Resistant Prostate Cancer

    Science.gov (United States)

    2016-10-01

    recently developed a series of small molecules that activate PP2A and thereby exert anticancer effects in cell culture and xenograft models. This...molecules that activate PP2A and thereby exert anticancer effects in cell culture and xenograft models. This proposal focuses on a third generation...months. 9 Changes that had a significant impact on expenditures Significant changes in use or care of human subjects, vertebrate animals

  16. Small Molecule-Induced Allosteric Activation of the Vibrio Cholerae RTX Cysteine Protease Domain

    Energy Technology Data Exchange (ETDEWEB)

    Lupardus, P.J.; Shen, A.; Bogyo, M.; Garcia, K.C.

    2009-05-19

    Vibrio cholerae RTX (repeats in toxin) is an actin-disrupting toxin that is autoprocessed by an internal cysteine protease domain (CPD). The RTX CPD is efficiently activated by the eukaryote-specific small molecule inositol hexakisphosphate (InsP{sub 6}), and we present the 2.1 angstrom structure of the RTX CPD in complex with InsP{sub 6}. InsP{sub 6} binds to a conserved basic cleft that is distant from the protease active site. Biochemical and kinetic analyses of CPD mutants indicate that InsP{sub 6} binding induces an allosteric switch that leads to the autoprocessing and intracellular release of toxin-effector domains.

  17. A small-molecule inhibitor of the ubiquitin activating enzyme for cancer treatment.

    Science.gov (United States)

    Hyer, Marc L; Milhollen, Michael A; Ciavarri, Jeff; Fleming, Paul; Traore, Tary; Sappal, Darshan; Huck, Jessica; Shi, Judy; Gavin, James; Brownell, Jim; Yang, Yu; Stringer, Bradley; Griffin, Robert; Bruzzese, Frank; Soucy, Teresa; Duffy, Jennifer; Rabino, Claudia; Riceberg, Jessica; Hoar, Kara; Lublinsky, Anya; Menon, Saurabh; Sintchak, Michael; Bump, Nancy; Pulukuri, Sai M; Langston, Steve; Tirrell, Stephen; Kuranda, Mike; Veiby, Petter; Newcomb, John; Li, Ping; Wu, Jing Tao; Powe, Josh; Dick, Lawrence R; Greenspan, Paul; Galvin, Katherine; Manfredi, Mark; Claiborne, Chris; Amidon, Benjamin S; Bence, Neil F

    2018-02-01

    The ubiquitin-proteasome system (UPS) comprises a network of enzymes that is responsible for maintaining cellular protein homeostasis. The therapeutic potential of this pathway has been validated by the clinical successes of a number of UPS modulators, including proteasome inhibitors and immunomodulatory imide drugs (IMiDs). Here we identified TAK-243 (formerly known as MLN7243) as a potent, mechanism-based small-molecule inhibitor of the ubiquitin activating enzyme (UAE), the primary mammalian E1 enzyme that regulates the ubiquitin conjugation cascade. TAK-243 treatment caused depletion of cellular ubiquitin conjugates, resulting in disruption of signaling events, induction of proteotoxic stress, and impairment of cell cycle progression and DNA damage repair pathways. TAK-243 treatment caused death of cancer cells and, in primary human xenograft studies, demonstrated antitumor activity at tolerated doses. Due to its specificity and potency, TAK-243 allows for interrogation of ubiquitin biology and for assessment of UAE inhibition as a new approach for cancer treatment.

  18. Discovery of novel small molecule activators of β-catenin signaling.

    Directory of Open Access Journals (Sweden)

    Folkert Verkaar

    Full Text Available Wnt/β-catenin signaling plays a major role in embryonic development and adult stem cell maintenance. Reduced activation of the Wnt/β-catenin pathway underlies neurodegenerative disorders and aberrations in bone formation. Screening of a small molecule compound library with a β-galactosidase fragment complementation assay measuring β-catenin nuclear entry revealed bona fide activators of β-catenin signaling. The compounds stabilized cytoplasmic β-catenin and activated β-catenin-dependent reporter gene activity. Although the mechanism through which the compounds activate β-catenin signaling has yet to be determined, several key regulators of Wnt/β-catenin signaling, including glycogen synthase kinase 3 and Frizzled receptors, were excluded as the molecular target. The compounds displayed remarkable selectivity, as they only induced β-catenin signaling in a human osteosarcoma U2OS cell line and not in a variety of other cell lines examined. Our data indicate that differences in cellular Wnt/β-catenin signaling machinery can be exploited to identify cell type-specific activators of Wnt/β-catenin signaling.

  19. Novel small-molecule AMPK activator orally exerts beneficial effects on diabetic db/db mice

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yuan-Yuan; Yu, Li-Fang; Zhang, Li-Na; Qiu, Bei-Ying; Su, Ming-Bo; Wu, Fang; Chen, Da-Kai; Pang, Tao; Gu, Min; Zhang, Wei; Ma, Wei-Ping; Jiang, Hao-Wen; Li, Jing-Ya, E-mail: jyli@mail.shcnc.ac.cn; Nan, Fa-Jun, E-mail: fjnan@mail.shcnc.ac.cn; Li, Jia, E-mail: jli@mail.shcnc.ac.cn

    2013-12-01

    AMP-activated protein kinase (AMPK), which is a pivotal guardian of whole-body energy metabolism, has become an attractive therapeutic target for metabolic syndrome. Previously, using a homogeneous scintillation proximity assay, we identified the small-molecule AMPK activator C24 from an optimization based on the original allosteric activator PT1. In this paper, the AMPK activation mechanism of C24 and its potential beneficial effects on glucose and lipid metabolism on db/db mice were investigated. C24 allosterically stimulated inactive AMPK α subunit truncations and activated AMPK heterotrimers by antagonizing autoinhibition. In primary hepatocytes, C24 increased the phosphorylation of AMPK downstream target acetyl-CoA carboxylase dose-dependently without changing intracellular AMP/ATP ratio, indicating its allosteric activation in cells. Through activating AMPK, C24 decreased glucose output by down-regulating mRNA levels of phosphoenolpyruvate carboxykinase (PEPCK) and glucose-6-phosphatase (G6Pase) in primary hepatocytes. C24 also decreased the triglyceride and cholesterol contents in HepG2 cells. Due to its improved bioavailability, chronic oral treatment with multiple doses of C24 significantly reduced blood glucose and lipid levels in plasma, and improved the glucose tolerance of diabetic db/db mice. The hepatic transcriptional levels of PEPCK and G6Pase were reduced. These results demonstrate that this orally effective activator of AMPK represents a novel approach to the treatment of metabolic syndrome. - Highlights: • C24 activates AMPK through antagonizing autoinhibition within α subunit. • C24 activates AMPK in hepatocytes and decreases glucose output via AMPK. • C24 exerts beneficial effects on diabetic db/db mice. • C24 represents a novel therapeutic for treatment of metabolic syndrome.

  20. Novel small-molecule AMPK activator orally exerts beneficial effects on diabetic db/db mice

    International Nuclear Information System (INIS)

    Li, Yuan-Yuan; Yu, Li-Fang; Zhang, Li-Na; Qiu, Bei-Ying; Su, Ming-Bo; Wu, Fang; Chen, Da-Kai; Pang, Tao; Gu, Min; Zhang, Wei; Ma, Wei-Ping; Jiang, Hao-Wen; Li, Jing-Ya; Nan, Fa-Jun; Li, Jia

    2013-01-01

    AMP-activated protein kinase (AMPK), which is a pivotal guardian of whole-body energy metabolism, has become an attractive therapeutic target for metabolic syndrome. Previously, using a homogeneous scintillation proximity assay, we identified the small-molecule AMPK activator C24 from an optimization based on the original allosteric activator PT1. In this paper, the AMPK activation mechanism of C24 and its potential beneficial effects on glucose and lipid metabolism on db/db mice were investigated. C24 allosterically stimulated inactive AMPK α subunit truncations and activated AMPK heterotrimers by antagonizing autoinhibition. In primary hepatocytes, C24 increased the phosphorylation of AMPK downstream target acetyl-CoA carboxylase dose-dependently without changing intracellular AMP/ATP ratio, indicating its allosteric activation in cells. Through activating AMPK, C24 decreased glucose output by down-regulating mRNA levels of phosphoenolpyruvate carboxykinase (PEPCK) and glucose-6-phosphatase (G6Pase) in primary hepatocytes. C24 also decreased the triglyceride and cholesterol contents in HepG2 cells. Due to its improved bioavailability, chronic oral treatment with multiple doses of C24 significantly reduced blood glucose and lipid levels in plasma, and improved the glucose tolerance of diabetic db/db mice. The hepatic transcriptional levels of PEPCK and G6Pase were reduced. These results demonstrate that this orally effective activator of AMPK represents a novel approach to the treatment of metabolic syndrome. - Highlights: • C24 activates AMPK through antagonizing autoinhibition within α subunit. • C24 activates AMPK in hepatocytes and decreases glucose output via AMPK. • C24 exerts beneficial effects on diabetic db/db mice. • C24 represents a novel therapeutic for treatment of metabolic syndrome

  1. Exploring surface landscapes with molecules: rotationally induced diffraction of H2on LiF(001) under fast grazing incidence conditions.

    Science.gov (United States)

    Del Cueto, M; Muzas, A S; Somers, M F; Kroes, G J; Díaz, C; Martín, F

    2017-06-28

    Atomic diffraction by surfaces under fast grazing incidence conditions has been used for almost a decade to characterize surface properties with more accuracy than with more traditional atomic diffraction methods. From six-dimensional solutions of the time-dependent Schrödinger equation, we show that diffraction of H 2 molecules under fast grazing incidence conditions could be even more informative for the characterization of ionic surfaces, due to the large anisotropic electrostatic interaction between the quadrupole moment of the molecule and the electric field created by the ionic crystal. Using the LiF(001) surface as a benchmark, we show that fast grazing incidence diffraction of H 2 strongly depends on the initial rotational state of the molecule, while rotationally inelastic processes are irrelevant. We demonstrate that, as a result of the anisotropy of the impinging projectile, initial rotational excitation leads to an increase in intensity of high-order diffraction peaks at incidence directions that satisfy precise symmetry constraints, thus providing a more detailed information on the surface characteristics than that obtained from low-order atomic diffraction peaks under fast grazing incidence conditions. As quadrupole-ion surface potentials are expected to accurately represent the interaction between H 2 and any surface with a marked ionic character, our analysis should be of general applicability to any of such surfaces. Finally, we show that a density functional theory description of the molecule-ion surface potential catches the main features observed experimentally.

  2. Water adsorption on non polar ZnO surfaces: from single molecules to multilayers

    Science.gov (United States)

    Kenmoe, Stephane; Biedermann, P. Ulrich

    2015-03-01

    The interface between water and ZnO plays an important role in many domains of technological relevance. Following the vital role of adsorbed water on substrate properties and the fascinating properties of interfacial water, there is a great interest in characterizing this interface. We use DFT to study the possible aggregation regimes that can form on the ZnO non-polar low-index (1010) and (1120) surfaces. We study the adsorption of water monomers, small water clusters like water dimers, water chains, ladder-like water structures, water thin films and water multilayers. Based on this, trends in binding energy as well as the binding mechanisms are analyzed to understand the driving forces and the nature of the fundamental interactions that stabilize the adsorbed layers.

  3. Inhibition of Host Cell Lysosome Spreading by Trypanosoma cruzi Metacyclic Stage-Specific Surface Molecule gp90 Downregulates Parasite Invasion.

    Science.gov (United States)

    Rodrigues, João Paulo Ferreira; Sant'ana, Guilherme Hideki Takahashi; Juliano, Maria Aparecida; Yoshida, Nobuko

    2017-09-01

    Successful infection by Trypanosoma cruzi , the agent of Chagas' disease, is critically dependent on host cell invasion by metacyclic trypomastigote (MT) forms. Two main metacyclic stage-specific surface molecules, gp82 and gp90, play determinant roles in target cell invasion in vitro and in oral T. cruzi infection in mice. The structure and properties of gp82, which is highly conserved among T. cruzi strains, are well known. Information on gp90 is still rather sparse. Here, we attempted to fill that gap. gp90, purified from poorly invasive G strain MT and expressing gp90 at high levels, inhibited HeLa cell lysosome spreading and the gp82-mediated internalization of a highly invasive CL strain MT expressing low levels of a diverse gp90 molecule. A recombinant protein containing the conserved C-terminal domain of gp90 exhibited the same properties as the native G strain gp90: it counteracted the host cell lysosome spreading induced by recombinant gp82 and exhibited an inhibitory effect on HeLa cell invasion by CL strain MT. Assays to identify the gp90 sequence associated with the property of downregulating MT invasion, using synthetic peptides spanning the gp90 C-terminal domain, revealed the sequence GVLYTADKEW. These data, plus the findings that lysosome spreading was induced upon HeLa cell interaction with CL strain MT, but not with G strain MT, and that in mixed infection CL strain MT internalization was inhibited by G strain MT, suggest that the inhibition of target cell lysosome spreading is the mechanism by which the gp90 molecule exerts its downregulatory role. Copyright © 2017 Rodrigues et al.

  4. Peptidomimetic Small Molecules Disrupt Type IV Secretion System Activity in Diverse Bacterial Pathogens

    Directory of Open Access Journals (Sweden)

    Carrie L. Shaffer

    2016-04-01

    Full Text Available Bacteria utilize complex type IV secretion systems (T4SSs to translocate diverse effector proteins or DNA into target cells. Despite the importance of T4SSs in bacterial pathogenesis, the mechanism by which these translocation machineries deliver cargo across the bacterial envelope remains poorly understood, and very few studies have investigated the use of synthetic molecules to disrupt T4SS-mediated transport. Here, we describe two synthetic small molecules (C10 and KSK85 that disrupt T4SS-dependent processes in multiple bacterial pathogens. Helicobacter pylori exploits a pilus appendage associated with the cag T4SS to inject an oncogenic effector protein (CagA and peptidoglycan into gastric epithelial cells. In H. pylori, KSK85 impedes biogenesis of the pilus appendage associated with the cag T4SS, while C10 disrupts cag T4SS activity without perturbing pilus assembly. In addition to the effects in H. pylori, we demonstrate that these compounds disrupt interbacterial DNA transfer by conjugative T4SSs in Escherichia coli and impede vir T4SS-mediated DNA delivery by Agrobacterium tumefaciens in a plant model of infection. Of note, C10 effectively disarmed dissemination of a derepressed IncF plasmid into a recipient bacterial population, thus demonstrating the potential of these compounds in mitigating the spread of antibiotic resistance determinants driven by conjugation. To our knowledge, this study is the first report of synthetic small molecules that impair delivery of both effector protein and DNA cargos by diverse T4SSs.

  5. Mytilus galloprovincialis myticin C: a chemotactic molecule with antiviral activity and immunoregulatory properties.

    Directory of Open Access Journals (Sweden)

    Pablo Balseiro

    Full Text Available Previous research has shown that an antimicrobial peptide (AMP of the myticin class C (Myt C is the most abundantly expressed gene in cDNA and suppressive subtractive hybridization (SSH libraries after immune stimulation of mussel Mytilus galloprovincialis. However, to date, the expression pattern, the antimicrobial activities and the immunomodulatory properties of the Myt C peptide have not been determined. In contrast, it is known that Myt C mRNA presents an unusual and high level of polymorphism of unidentified biological significance. Therefore, to provide a better understanding of the features of this interesting molecule, we have investigated its function using four different cloned and expressed variants of Myt C cDNA and polyclonal anti-Myt C sera. The in vivo results suggest that this AMP, mainly present in hemocytes, could be acting as an immune system modulator molecule because its overexpression was able to alter the expression of mussel immune-related genes (as the antimicrobial peptides Myticin B and Mytilin B, the C1q domain-containing protein MgC1q, and lysozyme. Moreover, the in vitro results indicate that Myt C peptides have antimicrobial and chemotactic properties. Their recombinant expression in a fish cell line conferred protection against two different fish viruses (enveloped and non-enveloped. Cell extracts from Myt C expressing fish cells were also able to attract hemocytes. All together, these results suggest that Myt C should be considered not only as an AMP but also as the first chemokine/cytokine-like molecule identified in bivalves and one of the few examples in all of the invertebrates.

  6. Nuclear factor kappaB-mediated down-regulation of adhesion molecules: possible mechanism for inhibitory activity of bigelovin against inflammatory monocytes adhesion to endothelial cells.

    Science.gov (United States)

    Nam, Kung-Woo; Oh, Goo Taeg; Seo, Eun-Kyoung; Kim, Kyeong Ho; Koo, Uk; Lee, Sung-Jin; Mar, Woongchon

    2009-06-22

    The flowers of Inula britannica L. var. chinensis (Rupr.) Reg. (Compositae) are used in traditional medicine to treat asthma, chronic bronchitis, and acute pleurisy in China and Korea. However, the pharmacological actions of Inula britannica L. var. chinensis on endothelial cells and inflammatory monocytes are not clear. In this study, we investigated whether bigelovin, a sesquiterpene lactone isolated from the flowers of Inula britannica L. var. chinensis, inhibits monocyte adhesion and adhesion molecule expression in brain endothelial cells. We measured tumor necrosis factor-alpha (TNF-alpha)-enhanced Raw264.7 monocyte binding to brain endothelial cells and the levels of cell adhesion molecules, including vascular adhesion molecule-1 (VCAM-1), intracellular adhesion molecule-1 (ICAM-1), and endothelial-selectin (E-selectin) on the surface of brain endothelial cells. Bigelovin significantly inhibited these in a dose-dependent manner without affecting cell viability. Furthermore, bigelovin suppressed the nuclear factor kappaB (NF-kappaB) promoter-driven luciferase activity, NF-kappaB activation, and degradation of NF-kappaB inhibitor protein alpha (IkappaBalpha). These results indicate that bigelovin inhibits inflammatory monocyte adhesion to endothelial cells and the expression of VCAM-1, ICAM-1, and E-selectin by blocking IkappaBalpha degradation and NF-kappaB activation.

  7. Theoretical estimation of optical hyperpolarizability appearance in fullerene molecule and carbon nanotubes interacting with ionic crystal surface

    Science.gov (United States)

    Mestechkin, M. M.

    2007-05-01

    The first hyperpolarizability (HP) of fullerene and finite length carbon nanotubes (FCN), attached to the neutral surfaces of SiO 2 (1 1 0), CdS(1 1 2 0), and CdTe(1 1 0) crystals, is calculated in the framework of the semi-empirical version of the time-dependent Hartree-Fock theory (TDHF). The norm of β-vector invariant, induced by the substrate, is of the same order as in some organic molecules with the observed nonlinear optical properties. The orthogonal to the substrate β-component is responsible for generation of the second harmonic by fullerene according to Hoshi and co-authors [H. Hoshi, N. Nakamura, Y. Maruyama, T. Nakagawa, S. Suzuki, H. Shiromaru, Y. Achiba, Jpn. J. Appl. Phys. 30 (1991) L1397]. The calculated value of this component is shown sufficient for the weak generation. It is found that zig-zag FCN, in contrast to armchair FCN, are characterized by the resonant behaviour of HP for second harmonic generation (SHG) at low frequencies due to the existence of quasi-degenerate (hyperbolic) levels in the close vicinity of the Fermi level. This ability is created by the external ionic crystal potential and affected by mutual electron interaction of molecules in the layer.

  8. Machine learning of single molecule free energy surfaces and the impact of chemistry and environment upon structure and dynamics.

    Science.gov (United States)

    Mansbach, Rachael A; Ferguson, Andrew L

    2015-03-14

    The conformational states explored by polymers and proteins can be controlled by environmental conditions (e.g., temperature, pressure, and solvent) and molecular chemistry (e.g., molecular weight and side chain identity). We introduce an approach employing the diffusion map nonlinear machine learning technique to recover single molecule free energy landscapes from molecular simulations, quantify changes to the landscape as a function of external conditions and molecular chemistry, and relate these changes to modifications of molecular structure and dynamics. In an application to an n-eicosane chain, we quantify the thermally accessible chain configurations as a function of temperature and solvent conditions. In an application to a family of polyglutamate-derivative homopeptides, we quantify helical stability as a function of side chain length, resolve the critical side chain length for the helix-coil transition, and expose the molecular mechanisms underpinning side chain-mediated helix stability. By quantifying single molecule responses through perturbations to the underlying free energy surface, our approach provides a quantitative bridge between experimentally controllable variables and microscopic molecular behavior, guiding and informing rational engineering of desirable molecular structure and function.

  9. Comparison between the classical interaction energy and periodic Hartree-Fock binding energies for the interaction between molecules and surfaces

    International Nuclear Information System (INIS)

    Chacon-Taylor, M.R.; McCarthy, M.I.

    1995-01-01

    The energetics of the H 2 O/MgO(001), HCl/MgO(001), and NH 3 /MgO(001) interface were investigated using the ab initio periodic Hartree-Fock LCAO method and a classical interaction energy model. The QM calculations treated a system that was periodic in two dimensions with the adsorbate approaching a three-layer slab of MgO(001). The authors used an approximation to the classical interaction energy, where the surface is represented by its potential, electric field, and electric field derivatives at the positions of the molecule center of mass, and the molecule is described by its charge, electric dipole, electric quadrupole and polarizability. The potential, electric field and electric field gradient are obtained for the clean three-layer slab using the ab initio periodic Hartree-Fock LCAO method (CRYSTAL) and an optimized split valence basis 8-61G on Mg and 8-51G on O. The charge, electric dipole, and electric quadrupole are calculated using ab initio Hartree-Fock theory (GAUSSIAN-92) with a 6-31G* basis set while the SCF polarizability is determined analytically using the same basis set

  10. Desorption Dynamics, Internal Energies and Imaging of Organic Molecules from Surfaces with Laser Desorption and Vacuum Ultraviolet (VUV) Photoionization

    Energy Technology Data Exchange (ETDEWEB)

    Kostko, Oleg; Takahashi, Lynelle K.; Ahmed, Musahid

    2011-04-05

    There is enormous interest in visualizing the chemical composition of organic material that comprises our world. A convenient method to obtain molecular information with high spatial resolution is imaging mass spectrometry. However, the internal energy deposited within molecules upon transfer to the gas phase from a surface can lead to increased fragmentation and to complications in analysis of mass spectra. Here it is shown that in laser desorption with postionization by tunable vacuum ultraviolet (VUV) radiation, the internal energy gained during laser desorption leads to minimal fragmentation of DNA bases. The internal temperature of laser-desorbed triacontane molecules approaches 670 K, whereas the internal temperature of thymine is 800 K. A synchrotron-based VUV postionization technique for determining translational temperatures reveals that biomolecules have translational temperatures in the range of 216-346 K. The observed low translational temperatures, as well as their decrease with increased desorption laser power is explained by collisional cooling. An example of imaging mass spectrometry on an organic polymer, using laser desorption VUV postionization shows 5 mu m feature details while using a 30 mu m laser spot size and 7 ns duration. Applications of laser desorption postionization to the analysis of cellulose, lignin and humic acids are briefly discussed.

  11. Effects of the small molecule HERG activator NS1643 on Kv11.3 channels.

    Directory of Open Access Journals (Sweden)

    Arne Bilet

    Full Text Available NS1643 is one of the small molecule HERG (Kv11.1 channel activators and has also been found to increase erg2 (Kv11.2 currents. We now investigated whether NS1643 is also able to act as an activator of Kv11.3 (erg3 channels expressed in CHO cells. Activation of rat Kv11.3 current occurred in a dose-dependent manner and maximal current increasing effects were obtained with 10 µM NS1643. At this concentration, steady-state outward current increased by about 80% and the current increase was associated with a significant shift in the voltage dependence of activation to more negative potentials by about 15 mV. In addition, activation kinetics were accelerated, whereas deactivation was slowed. There was no significant effect on the kinetics of inactivation and recovery from inactivation. The strong current-activating agonistic effect of NS1643 did not result from a shift in the voltage dependence of Kv11.3 channel inactivation and was independent from external Na(+ or Ca(2+. At the higher concentration of 20 µM, NS1643 induced clearly less current increase. The left shift in the voltage dependence of activation reversed and the voltage sensitivity of activation dramatically decreased along with a slowing of Kv11.3 channel activation. These data show that, in comparison to other Kv11 family members, NS1643 exerts distinct effects on Kv11.3 channels with especially pronounced partial antagonistic effects at higher concentration.

  12. Occurrence of Surface Active Agents in the Environment

    Directory of Open Access Journals (Sweden)

    Ewa Olkowska

    2014-01-01

    Full Text Available Due to the specific structure of surfactants molecules they are applied in different areas of human activity (industry, household. After using and discharging from wastewater treatment plants as effluent stream, surface active agents (SAAs are emitted to various elements of the environment (atmosphere, waters, and solid phases, where they can undergo numerous physic-chemical processes (e.g., sorption, degradation and freely migrate. Additionally, SAAs present in the environment can be accumulated in living organisms (bioaccumulation, what can have a negative effect on biotic elements of ecosystems (e.g., toxicity, disturbance of endocrine equilibrium. They also cause increaseing solubility of organic pollutants in aqueous phase, their migration, and accumulation in different environmental compartments. Moreover, surfactants found in aerosols can affect formation and development of clouds, which is associated with cooling effect in the atmosphere and climate changes. The environmental fate of SAAs is still unknown and recognition of this problem will contribute to protection of living organisms as well as preservation of quality and balance of various ecosystems. This work contains basic information about surfactants and overview of pollution of different ecosystems caused by them (their classification and properties, areas of use, their presence, and behavior in the environment.

  13. ADSORPTION OF ASSOCIATING FLUIDS AT ACTIVE SURFACES: A DENSITY FUNCTIONAL THEORY

    Directory of Open Access Journals (Sweden)

    S.Tripathi

    2003-01-01

    Full Text Available We present a density functional theory (DFT to describe adsorption in systems where molecules of associating fluids can bond (or associate with discrete, localized functional groups attached to the surfaces, in addition to other fluid molecules. For such systems as water adsorbing on activated carbon, silica, clay minerals etc. this is a realistic model to account for surface heterogeneity rather than using a continuous smeared surface-fluid potential employed in most of the theoretical works on adsorption on heterogeneous surfaces. Association is modelled within the framework of first order thermodynamic perturbation theory (TPT1. The new theory accurately predicts the distribution of bonded and non-bonded species and adsorption behavior under various conditions of bulk pressure, surface-fluid and fluid-fluid association strengths. Competition between the surface-fluid and fluid-fluid association is analyzed for fluids with multiple association sites and its impact on adsorption is discussed. The theory, supported by simulations demonstrates that the extent and the nature of adsorption (e.g. monolayer vary with the number of association sites on the fluid molecules.

  14. Surface diffusion of long chainlike molecules: The role of memory effects and stiffness on effective diffusion barriers

    DEFF Research Database (Denmark)

    Hjelt, T.; Vattulainen, Ilpo Tapio

    2000-01-01

    studies with chains of different lengths lead to a conclusion that, for a single diffusing chain, the memory contribution in E-A(T) decreases along with an increasing chain length and is almost negligible in the case of very long chains. Finally, we close this work by discussing our results in light......We study the coverage dependence of surface diffusion for chainlike molecules by the fluctuating-bond model with a Monte Carlo dynamics. The model includes short-ranged excluded volume interactions between different chains as well as an intrachain bond angle potential to describe the chain...... stiffness. Our primary aim is to consider the role played by chain stiffness and the resulting memory effects in tracer diffusion, and in particular their role in the effective tracer diffusion barrier E-A(T) extracted from the well-known Arrhenius form. We show that the memory effects in tracer diffusion...

  15. Surface-supported Ag islands stabilized by a quantum size effect: Their interaction with small molecules relevant to ethylene epoxidation

    Energy Technology Data Exchange (ETDEWEB)

    Shao, Dahai [Iowa State Univ., Ames, IA (United States)

    2013-05-15

    This dissertation focuses on how QSE-stabilized, surface-supported Ag nanoclusters will interact with ethylene or oxygen. Experiments are performed to determine whether the QSE-mediated Ag islands react differently toward adsorption of ethylene or oxygen, or whether the adsorption of these small molecules will affect the QSE-mediated stability of Ag islands. Studies of the interaction of oxygen with Ag/Si(111)-7×7 were previously reported, but these studies were performed at a low Ag coverage where 3D Ag islands were not formed. So the study of such a system at a higher Ag coverage will be a subject of this work. The interaction of ethylene with Ag/Si(111)-7×7, as well as the interaction of oxygen with Ag/NiAl(110) are also important parts of this study.

  16. Accurate adsorption energies of small molecules on oxide surfaces: CO-MgO(001).

    Science.gov (United States)

    Boese, A Daniel; Sauer, Joachim

    2013-10-21

    A hybrid MP2:DFT + D optimization method is applied using a 3 × 3 × 2 cluster model (Mg9O9) embedded in a 4 × 4 × 4 slab model. The calculated CO-Mg(2+) distance is 248 pm, and the calculated CO frequency (blue) shift is 20 cm(-1), 6 cm(-1) larger than the experimental value. For the structure obtained, MP2 calculations with basis set extrapolation on a series of cluster models of increasing size are performed. Taking into account the difference in the periodic limit at the DFT + D level, 20.9 ± 0.7 kJ mol(-1) is obtained as the estimate for the full periodic MP2 limit for the energy of CO desorption from the MgO(001) surface. CCSD(T) corrections are evaluated for the Mg9O9 cluster model using an augmented double-zeta basis set. Basis set extension effects are examined for smaller models. For a loading of Θ = 1/8, the estimated CCSD(T) value is 21.0 ± 1.0 kJ mol(-1), which is 0.4 ± 1.0 kJ mol(-1) larger than the (electronic) desorption energy derived in this study from TPD desorption barriers reported in the literature.

  17. Screening of pharmacologically active small molecule compounds identifies antifungal agents against Candida biofilms

    Directory of Open Access Journals (Sweden)

    Takao eWatamoto

    2015-12-01

    Full Text Available Candida species have emerged as important and common opportunistic human pathogens, particularly in immunocompromised individuals. The current antifungal therapies either have toxic side effects or are insufficiently effect. The aim of this study is develop new small-molecule antifungal compounds by library screening methods using C. albicans, and to evaluate their antifungal effects on Candida biofilms and cytotoxic effects on human cells. Wild-type C. albicans strain SC5314 was used in library screening. To identify antifungal compounds, we screened a small-molecule library of 1,280 pharmacologically active compounds (LOPAC1280TM using an antifungal susceptibility test (AST. To investigate the antifungal effects of the hit compounds, ASTs were conducted using Candida strains in various growth modes, including biofilms. We tested the cytotoxicity of the hit compounds using human gingival fibroblast (hGF cells to evaluate their clinical safety. Only 35 compounds were identified by screening, which inhibited the metabolic activity of C. albicans by >50%. Of these, 26 compounds had fungistatic effects and 9 compounds had fungicidal effects on C. albicans. Five compounds, BAY11-7082, BAY11-7085, sanguinarine chloride hydrate, ellipticine and CV-3988, had strong fungicidal effects and could inhibit the metabolic activity of Candida biofilms. However, BAY11-7082, BAY11-7085, sanguinarine chloride hydrate and ellipticine were cytotoxic to hGF cells at low concentrations. CV-3988 showed no cytotoxicity at a fungicidal concentration.Four of the compounds identified, BAY11-7082, BAY11-7085, sanguinarine chloride hydrate and ellipticine, had toxic effects on Candida strains and hGF cells. In contrast, CV-3988 had fungicidal effects on Candida strains, but low cytotoxic effects on hGF cells. Therefore, this screening reveals agent, CV-3988 that was previously unknown to be antifungal agent, which could be a novel therapies for superficial mucosal

  18. The Potential of Stimuli-Responsive Nanogels in Drug and Active Molecule Delivery for Targeted Therapy

    Directory of Open Access Journals (Sweden)

    Marta Vicario-de-la-Torre

    2017-05-01

    Full Text Available Nanogels (NGs are currently under extensive investigation due to their unique properties, such as small particle size, high encapsulation efficiency and protection of active agents from degradation, which make them ideal candidates as drug delivery systems (DDS. Stimuli-responsive NGs are cross-linked nanoparticles (NPs, composed of polymers, natural, synthetic, or a combination thereof that can swell by absorption (uptake of large amounts of solvent, but not dissolve due to the constituent structure of the polymeric network. NGs can undergo change from a polymeric solution (swell form to a hard particle (collapsed form in response to (i physical stimuli such as temperature, ionic strength, magnetic or electric fields; (ii chemical stimuli such as pH, ions, specific molecules or (iii biochemical stimuli such as enzymatic substrates or affinity ligands. The interest in NGs comes from their multi-stimuli nature involving reversible phase transitions in response to changes in the external media in a faster way than macroscopic gels or hydrogels due to their nanometric size. NGs have a porous structure able to encapsulate small molecules such as drugs and genes, then releasing them by changing their volume when external stimuli are applied.

  19. Expression of adhesion molecules and the proliferative activity of carcinosarcoma of the ovary.

    Science.gov (United States)

    Hirano, Hiroshi; Kizaki, Tomohiko; Ito, Takashi; Okimura, Akira; Yamanegi, Koji; Nakasho, Keiji

    2014-12-01

    To clarify the mechanism underlying the formation of a sarcomatous component of ovarian carcinosarcoma, we investigated the expression of adhesion molecules and the proliferative activity of carcinosarcomas. We immunohistochemically examined the expression of E-cadherin and β-catenin, and the Ki-67 labeling index (Ki-67 LI) in six carcinosarcomas containing endometrioid carcinoma as a carcinomatous component. The sarcomatous components of the carcinosarcomas did not express E-cadherin or β-catenin. All carcinomatous components expressed these molecules but the expression was reduced compared to that in endometrioid ovarian carcinomas. In five of the six carcinosarcomas, the Ki-67 LI of the sarcomatous component was less than that of the carcinomatous component. The present results suggest that a carcinomatous component transforms more easily than an ordinary endometrioid carcinoma from the viewpoint of the cell adhesion, and cells in a carcinomatous component continuously transform into sarcomatous cells during the growth of carcinosarcoma. Copyright© 2014 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved.

  20. Changes in lymphocyte subpopulations and adhesion/activation molecules following endotoxemia and major surgery

    DEFF Research Database (Denmark)

    Toft, P; Hokland, Marianne; Hansen, Tom Giedsing

    1995-01-01

    Major surgery as well as endotoxin-induced sepsis is accompanied by lymphocytopenia in peripheral blood. The purpose of this study was to investigate the redistribution of lymphocyte subpopulations and adhesion/activation molecules on lymphocytes. Twenty-four rats were included in the investigation....... Eight rats received an intraperitoneal injection of E. coli endotoxin (2 mg kg-1), eight rats had a sham operation performed while eight rats received isotonic saline and served as a control group. Blood samples were obtained by making an incision in the tail before and 2 and 5 h after surgery...... or administration of endotoxin or saline. After isolation of lymphocytes by gradient centrifugation, flow-cytometric immunophenotyping was performed using CD2, CD3, CD4, CD8, CD11/CD18, CD20, CD44 and MHC II monoclonal antibodies. Endotoxemia and surgery were both accompanied by increased serum cortisol...

  1. Osteogenic Activity of Locally Applied Small Molecule Drugs in a Rat Femur Defect Model

    Directory of Open Access Journals (Sweden)

    Jessica A. Cottrell

    2010-01-01

    Full Text Available The long-term success of arthroplastic joints is dependent on the stabilization of the implant within the skeletal site. Movement of the arthroplastic implant within the bone can stimulate osteolysis, and therefore methods which promote rigid fixation or bone growth are expected to enhance implant stability and the long-term success of joint arthroplasty. In the present study, we used a simple bilateral bone defect model to analyze the osteogenic activity of three small-molecule drug implants via microcomputerized tomography (micro-CT and histomorphometry. In this study, we show that local delivery of alendronate, but not lovastatin or omeprazole, led to significant new bone formation at the defect site. Since alendronate impedes osteoclast-development, it is theorized that alendronate treatment results in a net increase in bone formation by preventing osteoclast mediated remodeling of the newly formed bone and upregulating osteoblasts.

  2. Effect of polymer surface activity on cavitation nuclei stability against dissolution

    Science.gov (United States)

    Porter, Tyrone M.; Crum, Lawrence A.; Stayton, Patrick S.; Hoffman, Allan S.

    2004-08-01

    The persistence of acoustic cavitation in a pulsed wave ultrasound regime depends upon the ability of cavitation nuclei, i.e., bubbles, to survive the off time between pulses. Due to the dependence of bubble dissolution on surface tension, surface-active agents may affect the stability of bubbles against dissolution. In this study, measurements of bubble dissolution rates in solutions of the surface-active polymer poly(propyl acrylic acid) (PPAA) were conducted to test this premise. The surface activity of PPAA varies with solution pH and concentration of dissolved polymer molecules. The surface tension of PPAA solutions (55-72 dynes/cm) that associated with the polymer surface activity was measured using the Wilhelmy plate technique. Samples of these polymer solutions then were exposed to 1.1 MHz high intensity focused ultrasound, and the dissolution of bubbles created by inertial cavitation was monitored using an active cavitation detection scheme. Analysis of the pulse echo data demonstrated that bubble dissolution time was inversely proportional to the surface tension of the solution. Finally, comparison of the experimental results with dissolution times computed from the Epstein-Plesset equation suggests that the radii of residual bubbles from inertial cavitation increase as the surface tension decreases.

  3. Activation energy of fractional vortices and spectroscopy of a vortex molecule in long Josephson junction

    International Nuclear Information System (INIS)

    Buckenmaier, Kai

    2010-01-01

    This thesis is divided into two parts, the measurement of the activation energy of a fractional vortex and the spectroscopy of a vortex-molecule. Fractional vortices can be studied in long 0-κ Josephson junctions, where a jump of the Josephson phase is created artificially with a pair of tiny current injectors. To compensate for this phase discontinuity, a ρ vortex is formed. Here, ρ describes the vortex's so called topological charge. The ρ vortices are pinned at the discontinuity and they carry the fraction (ρ/2).Φ 0 of magnetic flux, with the magnetic flux quantum Φ 0 2.07.10 -15 . Two stable vortex configurations are possible, a direct Vortex and a complementary one. ρ depends on the injector current. When the bias current of the junction exceeds a characteristic threshold, which dependents on ρ, the Lorentz force is bigger than the pinning force of the vortex and a fluxon is pulled away. In this case a complementary (ρ-2π) vortex is left behind. This switching of the ρ vortex and the resulting emission of a fluxon can be described as a Kramers like escape of a particle out of a tilted washboard potential. The washboard potential is tilted to the point where the barrier is small enough, so that the particle can escape via thermal or quantum fluctuations. In the case of thermal fluctuations the barrier height is called activation energy. The activation energy can be determined by measuring the junction's switching current statistics. In this thesis, the activation energy, necessary for the vortex escape, was measured as a function of ρ and a homogenous external magnetic field perpendicular to the junction. The main focus was the investigation of 0-π junctions. The temperature dependence of the activation energy was investigated, too. It turns out, that the transition-state-theory is convenient to describe the switching probability of the standard Nb-AlO x -Nb junctions at 4.2 K. For the measurements at 0.5 K a model of low to intermediate damping

  4. Phase properties of elastic waves in systems constituted of adsorbed diatomic molecules on the (001) surface of a simple cubic crystal

    Science.gov (United States)

    Deymier, P. A.; Runge, K.

    2018-03-01

    A Green's function-based numerical method is developed to calculate the phase of scattered elastic waves in a harmonic model of diatomic molecules adsorbed on the (001) surface of a simple cubic crystal. The phase properties of scattered waves depend on the configuration of the molecules. The configurations of adsorbed molecules on the crystal surface such as parallel chain-like arrays coupled via kinks are used to demonstrate not only linear but also non-linear dependency of the phase on the number of kinks along the chains. Non-linear behavior arises for scattered waves with frequencies in the vicinity of a diatomic molecule resonance. In the non-linear regime, the variation in phase with the number of kinks is formulated mathematically as unitary matrix operations leading to an analogy between phase-based elastic unitary operations and quantum gates. The advantage of elastic based unitary operations is that they are easily realizable physically and measurable.

  5. Atomic force microscopy imaging and single molecule recognition force spectroscopy of coat proteins on the surface of Bacillus subtilis spore.

    Science.gov (United States)

    Tang, Jilin; Krajcikova, Daniela; Zhu, Rong; Ebner, Andreas; Cutting, Simon; Gruber, Hermann J; Barak, Imrich; Hinterdorfer, Peter

    2007-01-01

    Coat assembly in Bacillus subtilis serves as a tractable model for the study of the self-assembly process of biological structures and has a significant potential for use in nano-biotechnological applications. In the present study, the morphology of B. subtilis spores was investigated by magnetically driven dynamic force microscopy (MAC mode atomic force microscopy) under physiological conditions. B. subtilis spores appeared as prolate structures, with a length of 0.6-3 microm and a width of about 0.5-2 microm. The spore surface was mainly covered with bump-like structures with diameters ranging from 8 to 70 nm. Besides topographical explorations, single molecule recognition force spectroscopy (SMRFS) was used to characterize the spore coat protein CotA. This protein was specifically recognized by a polyclonal antibody directed against CotA (anti-CotA), the antibody being covalently tethered to the AFM tip via a polyethylene glycol linker. The unbinding force between CotA and anti-CotA was determined as 55 +/- 2 pN. From the high-binding probability of more than 20% in force-distance cycles it is concluded that CotA locates in the outer surface of B. subtilis spores. Copyright (c) 2007 John Wiley & Sons, Ltd.

  6. Probing the interactions of organic molecules, nanomaterials, and microbes with solid surfaces using quartz crystal microbalances: methodology, advantages, and limitations.

    Science.gov (United States)

    Huang, Rixiang; Yi, Peng; Tang, Yuanzhi

    2017-06-21

    Quartz crystal microbalances (QCMs) provide a new analytical opportunity and prospect to characterize many environmental processes at solid/liquid interfaces, thanks to their almost real-time measurement of physicochemical changes on their quartz sensor. This work reviews the applications of QCMs in probing the interactions of organic molecules, nanomaterials (NMs) and microbes with solid surfaces. These interfacial interactions are relevant to critical environmental processes such as biofilm formation, fate and transport of NMs, fouling in engineering systems and antifouling practices. The high sensitivity, real-time monitoring, and simultaneous frequency and dissipation measurements make QCM-D a unique technique that helps reveal the interaction mechanisms for the abovementioned processes (e.g., driving forces, affinity, kinetics, and the interplay between surface chemistry and solution chemistry). On the other hand, QCM measurement is nonselective and spatially-dependent. Thus, caution should be taken during data analysis and interpretation, and it is necessary to cross-validate the results using complementary information from other techniques for more quantitative and accurate interpretation. This review summarizes the general methodologies for collecting and analyzing raw QCM data, as well as for evaluating the associated uncertainties. It serves to help researchers gain deeper insights into the fundamentals and applications of QCMs, and provides new perspectives on future research directions.

  7. Multivalent adhesion molecule 7 clusters act as signaling platform for host cellular GTPase activation and facilitate epithelial barrier dysfunction.

    Directory of Open Access Journals (Sweden)

    Jenson Lim

    2014-09-01

    Full Text Available Vibrio parahaemolyticus is an emerging bacterial pathogen which colonizes the gastrointestinal tract and can cause severe enteritis and bacteraemia. During infection, V. parahaemolyticus primarily attaches to the small intestine, where it causes extensive tissue damage and compromises epithelial barrier integrity. We have previously described that Multivalent Adhesion Molecule (MAM 7 contributes to initial attachment of V. parahaemolyticus to epithelial cells. Here we show that the bacterial adhesin, through multivalent interactions between surface-induced adhesin clusters and phosphatidic acid lipids in the host cell membrane, induces activation of the small GTPase RhoA and actin rearrangements in host cells. In infection studies with V. parahaemolyticus we further demonstrate that adhesin-triggered activation of the ROCK/LIMK signaling axis is sufficient to redistribute tight junction proteins, leading to a loss of epithelial barrier function. Taken together, these findings show an unprecedented mechanism by which an adhesin acts as assembly platform for a host cellular signaling pathway, which ultimately facilitates breaching of the epithelial barrier by a bacterial pathogen.

  8. The role of outer surface/inner bulk Brønsted acidic sites in the adsorption of a large basic molecule (simazine) on H-Y zeolite.

    Science.gov (United States)

    Sannino, Filomena; Pansini, Michele; Marocco, Antonello; Bonelli, Barbara; Garrone, Edoardo; Esposito, Serena

    2015-11-21

    The simple means adopted for investigating H-Y zeolite acidity in water is the pH-dependence of the amount of a basic molecule adsorbed under isochoric conditions, a technique capable of yielding, under equilibrium conditions, an estimate of the pKa value of the involved acidic centres: the behaviour with temperature of adsorbed amounts yields instead some information on thermodynamics. Simazine (Sim, 2-chloro-4,6-bis(ethylamino)-s-triazine) was chosen as an adsorbate because its transverse dimension (7.5 Å) is close to the opening of the supercage in the faujasite structure of H-Y (7.4 Å). In short term measurements, Sim adsorption at 25 °C occurs only at the outer surface of H-Y particles. Two types of mildly acidic centres are present (with pKaca. 7 and ca. 8, respectively) and no strong one is observed. Previous adsorption of ammonia from the gas phase discriminates between the two. The former survives, and shows features common with the silanols of amorphous silica. The latter is suppressed: because of this and other features distinguishing this site from silanol species (e.g. the formation of dimeric Sim2H(+) species, favoured by coverage and unfavoured by temperatures of adsorption higher than ambient temperature) a candidate is an Al based site. We propose a Lewis centre coordinating a water molecule, exhibiting acidic properties. This acidic water molecule can be replaced by the stronger base ammonia, also depleting inner strong Brønsted sites. A mechanism for the generation of the two sites from surface Brønsted species is proposed. Long term adsorption measurements at 25 °C already show the onset of the interaction with inner strongly acidic Brønsted sites: because of its size, activation is required for Sim to pass the supercage openings and reach inner acidic sites. When adsorption is run at 40-50 °C, uptake is much larger and increases with temperature. Isochoric measurements suggest a pKa value of ca. 3 compatible with its marked acidic

  9. In-situ Evaluation of Soil Organic Molecules: Functional Group Chemistry Aggregate Structures, Metal and Surface Complexation Using Soft X-Ray

    International Nuclear Information System (INIS)

    Myneni, Satish C.

    2008-01-01

    Organic molecules are common in all Earth surface environments, and their composition and chemistry play an important role in a variety of biogeochemical reactions, such as mineral weathering, nutrient cycling and the solubility and transport of contaminants. However, most of what we know about the chemistry of these molecules comes from spectroscopy and microscopy studies of organic molecules extracted from different natural systems using either inorganic or organic solvents. Although all these methods gave us clues about the composition of these molecules, their composition and structure change with the extraction and the type of ex-situ analysis, their true behavior is less well understood. The goal of this project is to develop synchrotron instrumentation for studying natural organics, and to apply these recently developed synchrotron X-ray spectroscopy and microscopy techniques for understanding the: (1) functional group composition of naturally occurring organic molecules; (2) macromolecular structures of organic molecules; and (3) the nature of interactions of organic molecules with mineral surfaces in different environmental conditions.

  10. Crystallographic structure of a small molecule SIRT1 activator-enzyme complex

    Science.gov (United States)

    Dai, Han; Case, April W.; Riera, Thomas V.; Considine, Thomas; Lee, Jessica E.; Hamuro, Yoshitomo; Zhao, Huizhen; Jiang, Yong; Sweitzer, Sharon M.; Pietrak, Beth; Schwartz, Benjamin; Blum, Charles A.; Disch, Jeremy S.; Caldwell, Richard; Szczepankiewicz, Bruce; Oalmann, Christopher; Yee Ng, Pui; White, Brian H.; Casaubon, Rebecca; Narayan, Radha; Koppetsch, Karsten; Bourbonais, Francis; Wu, Bo; Wang, Junfeng; Qian, Dongming; Jiang, Fan; Mao, Cheney; Wang, Minghui; Hu, Erding; Wu, Joe C.; Perni, Robert B.; Vlasuk, George P.; Ellis, James L.

    2015-07-01

    SIRT1, the founding member of the mammalian family of seven NAD+-dependent sirtuins, is composed of 747 amino acids forming a catalytic domain and extended N- and C-terminal regions. We report the design and characterization of an engineered human SIRT1 construct (mini-hSIRT1) containing the minimal structural elements required for lysine deacetylation and catalytic activation by small molecule sirtuin-activating compounds (STACs). Using this construct, we solved the crystal structure of a mini-hSIRT1-STAC complex, which revealed the STAC-binding site within the N-terminal domain of hSIRT1. Together with hydrogen-deuterium exchange mass spectrometry (HDX-MS) and site-directed mutagenesis using full-length hSIRT1, these data establish a specific STAC-binding site and identify key intermolecular interactions with hSIRT1. The determination of the interface governing the binding of STACs with human SIRT1 facilitates greater understanding of STAC activation of this enzyme, which holds significant promise as a therapeutic target for multiple human diseases.

  11. High pressure chemistry of red phosphorus by photo-activated simple molecules

    International Nuclear Information System (INIS)

    Ceppatelli, M; Bini, R; Caporali, M; Peruzzini, M; Fanetti, S

    2014-01-01

    High pressure (HP) is very effective in reducing intermolecular distances and inducing unexpected chemical reactions. In addition the photo-activation of the reactants in HP conditions can lead to very efficient and selective processes. The chemistry of phosphorus is currently based on the white molecular form. The red polymeric allotrope, despite more stable and much less toxic, has not attracted much attention so far. However, switching from the white to the red form would benefit any industrial procedure, especially from an environmental point of view. On the other side, water and ethanol are renewable, environmental friendly and largely available molecules, usable as reactants and photo-activators in HP conditions. Here we report a study on the HP photo-induced reactivity of red phosphorus with water and ethanol, showing the possibility of very efficient and selective processes, leading to molecular hydrogen and valuable phosphorus compounds. The reactions have been studied by means of FTIR and Raman spectroscopy and pressure has been generated using membrane Diamond (DAC) and Sapphire (SAC) anvil cells. HP reactivity has been activated by the two-photon absorption of near-UV wavelengths and occurred in total absence of solvents, catalysts and radical initiators, at room T and mild pressure conditions (0.2–1.5 GPa).

  12. Assessing the Antimicrobial Activity of Polyisoprene Based Surfaces

    Directory of Open Access Journals (Sweden)

    Hope Badawy

    2015-02-01

    Full Text Available There has been an intense research effort in the last decades in the field of biofouling prevention as it concerns many aspects of everyday life and causes problems to devices, the environment, and human health. Many different antifouling and antimicrobial materials have been developed to struggle against bacteria and other micro- and macro-organism attachment to different surfaces. However the “miracle solution” has still to be found. The research presented here concerns the synthesis of bio-based polymeric materials and the biological tests that showed their antifouling and, at the same time, antibacterial activity. The raw material used for the coating synthesis was natural rubber. The polyisoprene chains were fragmented to obtain oligomers, which had reactive chemical groups at their chain ends, therefore they could be modified to insert polymerizable and biocidal groups. Films were obtained by radical photopolymerization of the natural rubber derived oligomers and their structure was altered, in order to understand the mechanism of attachment inhibition and to increase the efficiency of the anti-biofouling action. The adhesion of three species of pathogenic bacteria and six strains of marine bacteria was studied. The coatings were able to inhibit bacterial attachment by contact, as it was verified that no detectable leaching of toxic molecules occurred.

  13. Plasma technology of the surface polymer activation

    International Nuclear Information System (INIS)

    Dutra, Jorge C.N.; Mello, Sandra C.; Massi, Marcos; Otani, Choyu; Maciel, Homero S.; Bittencourt, Edison

    2005-01-01

    A number of polymers, especially rubbers, require surface treatment to achieve a satisfactory level of adhesion. The surface of EPDM rubber vulcanized is high hydrophobicity and is not suited for a number of potential applications, in particular, for adhering to the polyurethane liner of solid rocket propellants. In this case, plasma treatment can be a very attractive process because it can efficiently increase the surface energy attributed to surface oxidation with the introduction of polar groups 1, 2. In order to investigate the influence of the parameters on the modifications of the treated surface samples of EPDM rubber by plasma generated by gas oxygen and argon, the water and methylene iodide contact angles were measured at room temperature with an image analyzing using the sessile drop technique 3 - 6 . (author)

  14. Ground-state thermodynamics of bistable redox-active donor-acceptor mechanically interlocked molecules.

    Science.gov (United States)

    Fahrenbach, Albert C; Bruns, Carson J; Cao, Dennis; Stoddart, J Fraser

    2012-09-18

    Fashioned through billions of years of evolution, biological molecular machines, such as ATP synthase, myosin, and kinesin, use the intricate relative motions of their components to drive some of life's most essential processes. Having control over the motions in molecules is imperative for life to function, and many chemists have designed, synthesized, and investigated artificial molecular systems that also express controllable motions within molecules. Using bistable mechanically interlocked molecules (MIMs), based on donor-acceptor recognition motifs, we have sought to imitate the sophisticated nanoscale machines present in living systems. In this Account, we analyze the thermodynamic characteristics of a series of redox-switchable [2]rotaxanes and [2]catenanes. Control and understanding of the relative intramolecular movements of components in MIMs have been vital in the development of a variety of applications of these compounds ranging from molecular electronic devices to drug delivery systems. These bistable donor-acceptor MIMs undergo redox-activated switching between two isomeric states. Under ambient conditions, the dominant translational isomer, the ground-state coconformation (GSCC), is in equilibrium with the less favored translational isomer, the metastable-state coconformation (MSCC). By manipulating the redox state of the recognition site associated with the GSCC, we can stimulate the relative movements of the components in these bistable MIMs. The thermodynamic parameters of model host-guest complexes provide a good starting point to rationalize the ratio of GSCC to MSCC at equilibrium. The bistable [2]rotaxanes show a strong correlation between the relative free energies of model complexes and the ground-state distribution constants (K(GS)). This relationship does not always hold for bistable [2]catenanes, most likely because of the additional steric and electronic constraints present when the two rings are mechanically interlocked with each other

  15. Endothelial juxtaposition of distinct adult stem cells activates angiogenesis signaling molecules in endothelial cells.

    Science.gov (United States)

    Mohammadi, Elham; Nassiri, Seyed Mahdi; Rahbarghazi, Reza; Siavashi, Vahid; Araghi, Atefeh

    2015-12-01

    Efficacy of therapeutic angiogenesis needs a comprehensive understanding of endothelial cell (EC) function and biological factors and cells that interplay with ECs. Stem cells are considered the key components of pro- and anti-angiogenic milieu in a wide variety of physiopathological states, and interactions of EC-stem cells have been the subject of controversy in recent years. In this study, the potential effects of three tissue-specific adult stem cells, namely rat marrow-derived mesenchymal stem cells (rBMSCs), rat adipose-derived stem cells (rADSCs) and rat muscle-derived satellite cells (rSCs), on the endothelial activation of key angiogenic signaling molecules, including VEGF, Ang-2, VEGFR-2, Tie-2, and Tie2-pho, were investigated. Human umbilical vein endothelial cells (HUVECs) and rat lung microvascular endothelial cells (RLMECs) were cocultured with the stem cells or incubated with the stem cell-derived conditioned media on Matrigel. Following HUVEC-stem cell coculture, CD31-positive ECs were flow sorted and subjected to western blotting to analyze potential changes in the expression of the pro-angiogenic signaling molecules. Elongation and co-alignment of the stem cells were seen along the EC tubes in the EC-stem cell cocultures on Matrigel, with cell-to-cell dye communication in the EC-rBMSC cocultures. Moreover, rBMSCs and rADSCs significantly improved endothelial tubulogenesis in both juxtacrine and paracrine manners. These two latter stem cells dynamically up-regulated VEGF, Ang-2, VREGR-2, and Tie-2 but down-regulated Tie2-pho and the Tie2-pho/Tie-2 ratio in HUVECs. Induction of pro-angiogenic signaling in ECs by marrow- and adipose-derived MSCs further indicates the significance of stem cell milieu in angiogenesis dynamics.

  16. Electrocatalytic activity of surface adsorbed ruthenium-alizarin complexone toward the oxidation of benzyl alcohol

    Energy Technology Data Exchange (ETDEWEB)

    Marques, Aldalea Lopes Brandes; Li Weihua; Marques, Edmar Pereira; Zhang Jiujun

    2004-03-01

    The surface electrochemical behavior of an adsorbed alizarin complexone (abbreviated as AC) and its surface coordination with Ru(II) were studied in aqueous solution at a pH range of 0-6. The surface complex of ruthenium with AC displays strong electrocatalytic activities toward benzyl alcohol. Based on the rotating disk electrode measurement, it is believed that the electrocatalytic oxidation of benzyl alcohol is a two-electron and two-proton process with benzaldehyde as a major product. On the other hand, ruthenium-AC surface complex has also shown catalytic activities toward electro-oxidation of several small organic molecules such as methanol, formic acid, formaldehyde, ethanol, and acetaldehyde.

  17. Quantum tunneling in real space: Tautomerization of single porphycene molecules on the (111) surface of Cu, Ag, and Au

    Science.gov (United States)

    Kumagai, Takashi; Ladenthin, Janina N.; Litman, Yair; Rossi, Mariana; Grill, Leonhard; Gawinkowski, Sylwester; Waluk, Jacek; Persson, Mats

    2018-03-01

    Tautomerization in single porphycene molecules is investigated on Cu(111), Ag(111), and Au(111) surfaces by a combination of low-temperature scanning tunneling microscopy (STM) experiments and density functional theory (DFT) calculations. It is revealed that the trans configuration is the thermodynamically stable form of porphycene on Cu(111) and Ag(111), whereas the cis configuration occurs as a meta-stable form. The trans → cis or cis → trans conversion on Cu(111) can be induced in an unidirectional fashion by injecting tunneling electrons from the STM tip or heating the surface, respectively. We find that the cis ↔ cis tautomerization on Cu(111) occurs spontaneously via tunneling, verified by the negligible temperature dependence of the tautomerization rate below ˜23 K. Van der Waals corrected DFT calculations are used to characterize the adsorption structures of porphycene and to map the potential energy surface of the tautomerization on Cu(111). The calculated barriers are too high to be thermally overcome at cryogenic temperatures used in the experiment and zero-point energy corrections do not change this picture, leaving tunneling as the most likely mechanism. On Ag(111), the reversible trans ↔ cis conversion occurs spontaneously at 5 K and the cis ↔ cis tautomerization rate is much higher than on Cu(111), indicating a significantly smaller tautomerization barrier on Ag(111) due to the weaker interaction between porphycene and the surface compared to Cu(111). Additionally, the STM experiments and DFT calculations reveal that tautomerization on Cu(111) and Ag(111) occurs with migration of porphycene along the surface; thus, the translational motion couples with the tautomerization coordinate. On the other hand, the trans and cis configurations are not discernible in the STM image and no tautomerization is observed for porphycene on Au(111). The weak interaction of porphycene with Au(111) is closest to the gas-phase limit and therefore the absence

  18. Discovery of Novel Small Molecules that Activate Satellite Cell Proliferation and Enhance Repair of Damaged Muscle.

    Science.gov (United States)

    Billin, Andrew N; Bantscheff, Marcus; Drewes, Gerard; Ghidelli-Disse, Sonja; Holt, Jason A; Kramer, Henning F; McDougal, Alan J; Smalley, Terry L; Wells, Carrow I; Zuercher, William J; Henke, Brad R

    2016-02-19

    Skeletal muscle progenitor stem cells (referred to as satellite cells) represent the primary pool of stem cells in adult skeletal muscle responsible for the generation of new skeletal muscle in response to injury. Satellite cells derived from aged muscle display a significant reduction in regenerative capacity to form functional muscle. This decrease in functional recovery has been attributed to a decrease in proliferative capacity of satellite cells. Hence, agents that enhance the proliferative abilities of satellite cells may hold promise as therapies for a variety of pathological settings, including repair of injured muscle and age- or disease-associated muscle wasting. Through phenotypic screening of isolated murine satellite cells, we identified a series of 2,4-diaminopyrimidines (e.g., 2) that increased satellite cell proliferation. Importantly, compound 2 was effective in accelerating repair of damaged skeletal muscle in an in vivo mouse model of skeletal muscle injury. While these compounds were originally prepared as c-Jun N-terminal kinase 1 (JNK-1) inhibitors, structure-activity analyses indicated JNK-1 inhibition does not correlate with satellite cell activity. Screening against a broad panel of kinases did not result in identification of an obvious molecular target, so we conducted cell-based proteomics experiments in an attempt to identify the molecular target(s) responsible for the potentiation of the satellite cell proliferation. These data provide the foundation for future efforts to design improved small molecules as potential therapeutics for muscle repair and regeneration.

  19. Inhibition of Streptococcus mutans polysaccharide synthesis by molecules targeting glycosyltransferase activity

    Directory of Open Access Journals (Sweden)

    Zhi Ren

    2016-04-01

    Full Text Available Glycosyltransferase (Gtf is one of the crucial virulence factors of Streptococcus mutans, a major etiological pathogen of dental caries. All the available evidence indicates that extracellular polysaccharide, particularly glucans produced by S. mutans Gtfs, contribute to the cariogenicity of dental biofilms. Therefore, inhibition of Gtf activity and the consequential polysaccharide synthesis may impair the virulence of cariogenic biofilms, which could be an alternative strategy to prevent the biofilm-related disease. Up to now, many Gtf inhibitors have been recognized in natural products, which remain the major and largely unexplored source of Gtf inhibitors. These include catechin-based polyphenols, flavonoids, proanthocyanidin oligomers, polymeric polyphenols, and some other plant-derived compounds. Metal ions, oxidizing agents, and some other synthetic compounds represent another source of Gtf inhibitors, with some novel molecules either discovered by structure-based virtual screening or synthesized based on key structures of known inhibitors as templates. Antibodies that inhibit one or more Gtfs have also been developed as topical agents. Although many agents have been shown to possess potent inhibitory activity against glucan synthesis by Gtfs, bacterial cell adherence, and caries development in animal models, much research remains to be performed to find out their mechanism of action, biological safety, cariostatic efficacies, and overall influence on the entire oral community. As a strategy to inhibit the virulence of cariogenic microbes rather than eradicate them from the microbial community, Gtf inhibition represents an approach of great potential to prevent dental caries.

  20. Membrane Active Small Molecules Show Selective Broad Spectrum Antibacterial Activity with No Detectable Resistance and Eradicate Biofilms.

    Science.gov (United States)

    Hoque, Jiaul; Konai, Mohini M; Gonuguntla, Spandhana; Manjunath, Goutham B; Samaddar, Sandip; Yarlagadda, Venkateswarlu; Haldar, Jayanta

    2015-07-23

    Treating bacterial biofilms with conventional antibiotics is limited due to ineffectiveness of the drugs and higher propensity to develop bacterial resistance. Development of new classes of antibacterial therapeutics with alternative mechanisms of action has become imperative. Herein, we report the design, synthesis, and biological evaluations of novel membrane-active small molecules featuring two positive charges, four nonpeptidic amide groups, and variable hydrophobic/hydrophilic (amphiphilic) character. The biocides synthesized via a facile methodology not only displayed good antibacterial activity against wild-type bacteria but also showed high activity against various drug-resistant bacteria such as methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus faecium (VRE), and β-lactam-resistant Klebsiella pneumoniae. Further, these biocides not only inhibited the formation of biofilms but also disrupted the established S. aureus and E. coli biofilms. The membrane-active biocides hindered the propensity to develop bacterial resistance. Moreover, the biocides showed negligible toxicity against mammalian cells and thus bear potential to be used as therapeutic agents.

  1. Surface composition of carburized tungsten trioxide and its catalytic activity

    International Nuclear Information System (INIS)

    Nakazawa, M.; Okamoto, H.

    1985-01-01

    The surface composition and electronic structure of carburized tungsten trioxide are investigated using x-ray photoelectron spectroscopy (XPS). The relationship between the surface composition and the catalytic activity for methanol electro-oxidation is clarified. The tungsten carbide concentration in the surface layer increases with the carburization time. The formation of tungsten carbide enhances the catalytic activity. On the other hand, the presence of free carbon or tungsten trioxide in the surface layer reduces the activity remarkably. It is also shown that, the higher the electronic density of states near the Fermi level, the higher the catalytic activity

  2. Human Secretory IgM Antibodies Activate Human Complement and Offer Protection at Mucosal Surface.

    Science.gov (United States)

    Michaelsen, T E; Emilsen, S; Sandin, R H; Granerud, B K; Bratlie, D; Ihle, O; Sandlie, I

    2017-01-01

    IgM molecules circulate in serum as large polymers, mainly pentamers, which can be transported by the poly-Ig receptor (pIgR) across epithelial cells to mucosal surfaces and released as secretory IgM (SIgM). The mucosal SIgM molecules have non-covalently attached secretory component (SC), which is the extracellular part of pIgR which is cleaved from the epithelial cell membrane. Serum IgM antibodies do not contain SC and have previously been shown to make a conformational change from 'a star' to a 'staple' conformation upon reaction with antigens on a cell surface, enabling them to activate complement. However, it is not clear whether SIgM similarly can induce complement activation. To clarify this issue, we constructed recombinant chimeric (mouse/human) IgM antibodies against hapten 5-iodo-4-hydroxy-3-nitro-phenacetyl (NIP) and in addition studied polyclonal IgM formed after immunization with a meningococcal group B vaccine. The monoclonal and polyclonal IgM molecules were purified by affinity chromatography on a column containing human SC in order to isolate joining-chain (J-chain) containing IgM, followed by addition of excess amounts of soluble SC to create SIgM (IgM J+ SC+). These SIgM preparations were tested for complement activation ability and shown to be nearly as active as the parental IgM J+ molecules. Thus, SIgM may offer protection against pathogens at mucosal surface by complement-mediated cell lysis or by phagocytosis mediated by complement receptors present on effector cells on mucosa. © 2016 The Foundation for the Scandinavian Journal of Immunology.

  3. Activity of autoinducer two (AI-2) in bacteria isolated from surface ripened cheeses

    DEFF Research Database (Denmark)

    Gori, Klaus; Jespersen, Lene

    A large number of Gram-positive and Gram-negative bacteria have been found to produce the signaling molecule autoinducer two (AI-2), which is used for interspecies communication. In this study, AI-2 activity was for the first time determined in Arthrobacter nicotianae, Brevibacterium linens (BL2......). Corynebacterium casei, Microbacterium barkeri, Microbacterium gubbeenense and S. equorum subsp. linens (all isolated from the smear of surface ripened cheeses) using the AI-2 bioluminescence assay. This indicates that AI-2 signaling could take place between bacteria found in the smear of surface ripened cheeses....

  4. Antiviral activity of a small molecule deubiquitinase inhibitor occurs via induction of the unfolded protein response.

    Directory of Open Access Journals (Sweden)

    Jeffrey W Perry

    Full Text Available Ubiquitin (Ub is a vital regulatory component in various cellular processes, including cellular responses to viral infection. As obligate intracellular pathogens, viruses have the capacity to manipulate the ubiquitin (Ub cycle to their advantage by encoding Ub-modifying proteins including deubiquitinases (DUBs. However, how cellular DUBs modulate specific viral infections, such as norovirus, is poorly understood. To examine the role of DUBs during norovirus infection, we used WP1130, a small molecule inhibitor of a subset of cellular DUBs. Replication of murine norovirus in murine macrophages and the human norovirus Norwalk virus in a replicon system were significantly inhibited by WP1130. Chemical proteomics identified the cellular DUB USP14 as a target of WP1130 in murine macrophages, and pharmacologic inhibition or siRNA-mediated knockdown of USP14 inhibited murine norovirus infection. USP14 is a proteasome-associated DUB that also binds to inositol-requiring enzyme 1 (IRE1, a critical mediator of the unfolded protein response (UPR. WP1130 treatment of murine macrophages did not alter proteasome activity but activated the X-box binding protein-1 (XBP-1 through an IRE1-dependent mechanism. In addition, WP1130 treatment or induction of the UPR also reduced infection of other RNA viruses including encephalomyocarditis virus, Sindbis virus, and La Crosse virus but not vesicular stomatitis virus. Pharmacologic inhibition of the IRE1 endonuclease activity partially rescued the antiviral effect of WP1130. Taken together, our studies support a model whereby induction of the UPR through cellular DUB inhibition blocks specific viral infections, and suggest that cellular DUBs and the UPR represent novel targets for future development of broad spectrum antiviral therapies.

  5. Evaluation of the differential energy distribution of systems of non-thermally activated molecules

    International Nuclear Information System (INIS)

    Rogers, E.B.

    1986-01-01

    A non-thermally activated molecule may undergo pressure dependent deactivation or energy dependent decomposition. It should be possible to use the pressure dependent stabilization/decomposition yields to determine the energy distribution in non-thermal systems. The numerical technique of regularization has been applied to this chemical problem to evaluate this distribution. The resulting method has been tested with a number of simulated distributions and kinetic models. Application was then made to several real chemical systems to determine the energy distribution resulting from the primary excitation process. Testing showed the method to be quite effective in reproducing input distributions from simulated data in all test cases. The effect of experimental error proved to be negligible when the error-filled data were first smoothed with a parabolic spline. This method has been applied to three different hot atom activated systems. Application to 18 F-for-F substituted CH 3 CF 3 generated a broad distribution extending from 62 to 318 kcal/mol, with a median energy of 138 kcal/mol. The shape of this distribution (and those from the other applications) indicated the involvement of two mechanisms in the excitation process. Analysis of the T-for-H substituted CH 3 CH 2 F system showed a more narrow distribution (56-218 kcal/mol) with a median energy of 79.8 kcal/mol. The distribution of the T-for-H substituted CH 3 CH 2 Cl system, extending from 54.5 to 199 kcal/mol was seen to be quite similar. It was concluded that this method is a valid approach to evaluating differential energy distributions in non-thermal systems, specifically those activated by hot atom substitution

  6. Probing the rate-determining region of the potential energy surface for a prototypical ion-molecule reaction.

    Science.gov (United States)

    Xie, Changjian; Liu, Xinguo; Sweeny, Brendan C; Miller, Thomas M; Ard, Shaun G; Shuman, Nicholas S; Viggiano, Albert A; Guo, Hua

    2018-03-13

    We report a joint experimental-theoretical study of the F -  + HCl → HF + Cl - reaction kinetics. The experimental measurement of the rate coefficient at several temperatures was made using the selected ion flow tube method. Theoretical rate coefficients are calculated using the quasi-classical trajectory method on a newly developed global potential energy surface, obtained by fitting a large number of high-level ab initio points with augmentation of long-range electrostatic terms. In addition to good agreement between experiment and theory, analyses suggest that the ion-molecule reaction rate is significantly affected by shorter-range interactions, in addition to the traditionally recognized ion-dipole and ion-induced dipole terms. Furthermore, the statistical nature of the reaction is assessed by comparing the measured and calculated HF product vibrational state distributions to that predicted by the phase space theory.This article is part of the theme issue 'Modern theoretical chemistry'. © 2018 The Author(s).

  7. Ozonation of benzothiazole saturated-activated carbons: Influence of carbon chemical surface properties

    International Nuclear Information System (INIS)

    Valdes, H.; Zaror, C.A.

    2006-01-01

    The combined or sequential use of ozone and activated carbon to treat toxic effluents has increased in recent years. However, little is known about the influence of carbon surface active sites on ozonation of organic adsorbed pollutants. This paper presents experimental results on the effect of metal oxides and oxygenated surface groups on gaseous ozonation of spent activated carbons. Benzothiazole (BT) was selected as a target organic compound in this study due to its environmental concern. Activated carbons with different chemical surface composition were prepared from a Filtrasorb-400 activated carbon. Pre-treatment included: ozonation, demineralisation, and deoxygenation of activated carbon. Ozonation experiments of BT saturated-activated carbons were conducted in a fixed bed reactor loaded with 2 g of carbon samples. The reactor was fed with an O 2 /O 3 gas mixture (2 dm 3 /min, 5 g O 3 /h), for a given exposure time, in the range 10-120 min, at 298 K and 1 atm. Results show that extended gaseous ozonation of activated carbon saturated with BT led to the effective destruction of the adsorbate by oxidation reactions. Oxidation of BT adsorbed on activated carbon seemed to occur via both direct reaction with ozone molecules, and by oxygen radical species generated by catalytic ozone decomposition on metallic surface sites

  8. Investigation of multi-state charge-storage properties of redox-active organic molecules in silicon-molecular hybrid devices for DRAM and Flash applications

    Science.gov (United States)

    Gowda, Srivardhan Shivappa

    Molecular electronics has recently spawned a considerable amount of interest with several molecules possessing charge-conduction and charge-storage properties proposed for use in electronic devices. Hybrid silicon-molecular technology has the promise of augmenting the current silicon technology and provide for a transitional path to future molecule-only technology. The focus of this dissertation work has been on developing a class of hybrid silicon-molecular electronic devices for DRAM and Flash memory applications utilizing redox-active molecules. This work exploits the ability of molecules to store charges with single-electron precision at room temperature. The hybrid devices are fabricated by forming self-assembled monolayers of redox-active molecules on Si and oxide (SiO2 and HfO2) surfaces via formation of covalent linkages. The molecules possess discrete quantum states from which electrons can tunnel to the Si substrate at discrete applied voltages (oxidation process, cell write), leaving behind a positively charged layer of molecules. The reduction (erase) process, which is the process of electrons tunneling back from Si to the molecules, neutralizes the positively charged molecular monolayer. Hybrid silicon-molecular capacitor test structures were electrically characterized with an electrolyte gate using cyclic voltammetry (CyV) and impedance spectroscopy (CV) techniques. The redox voltages, kinetics (write/erase speeds) and charge-retention characteristics were found to be strongly dependent on the Si doping type and densities, and ambient light. It was also determined that the redox energy states in the molecules communicate with the valence band of the Si substrate. This allows tuning of write and read states by modulating minority carriers in n- and p-Si substrates. Ultra-thin dielectric tunnel barriers (SiO2, HfO2) were placed between the molecules and the Si substrate to augment charge-retention for Flash memory applications. The redox response was

  9. Surface activity of thymol: implications for an eventual pharmacological activity.

    Science.gov (United States)

    Sánchez, Mariela E; Turina, Anahí del V; García, Daniel A; Nolan, M Verónica; Perillo, María A

    2004-03-15

    In the present work, we studied the ability of thymol to affect the organization of model membranes and the activity of an intrinsic membrane protein, the GABA(A) receptor (GABA(A)-R). In this last aspect, we tried to elucidate if the action mechanism of this terpene at the molecular level, involves its binding to the receptor protein, changes in the organization of the receptor molecular environment, or both. The self-aggregation of thymol in water with a critical micellar concentration approximately = 4 microM and its ability to penetrate in monomolecular layers of soybean phosphatidylcholine (sPC) at the air-water interface, even at surface pressures above the equilibrium, lateral pressure of natural bilayers were demonstrated. Thymol affected the self-aggregation of Triton X-100 and the topology of sPC vesicles. It also increased the polarity of the membrane environment sensed by the electrochromic dye merocyanine. A dipolar moment of 1.341 Debye was calculated from its energy-minimized structure. Its effect on the binding of [3H]-flunitrazepam ([3H]-FNZ) to chick brain synaptosomal membranes changed qualitatively from a tendency to the inhibition to a clear activatory regime, up on changing the phase state of the terpene (from a monomeric to a self-aggregated state). Above its CMC, thymol increased the affinity of the binding of [3H]-FNZ (K(d-control)= 2.9, K(d-thymol)= 1.7 nM) without changing the receptor density (B(max-control)= 910, B(max-thymol)= 895 fmol/mg protein). The activatory effect of thymol on the binding of [ [3H]-FNZ was observed even in the presence of the allosteric activator gamma-aminobutyric acid (GABA) at a concentration of maximal activity, and was blocked by the GABA antagonist bicuculline. Changes in the dipolar arrangement and in the molecular packing of GABA(A)-R environment are discussed as possible mediators of the action mechanism of thymol.

  10. Adsorption mechanism of H2O molecule on the Li4SiO4 (0 1 0) surface from first principles

    Science.gov (United States)

    Kong, Xianggang; Yu, You; Ma, Shenggui; Gao, Tao; Xiao, Chengjian; Chen, Xiaojun

    2018-01-01

    The adsorption and dissociation behaviors of molecular H2O on the Li4SiO4 (0 1 0) surface have been systematically studied by first-principles calculations. It is found that the adsorbed H2O molecule mainly interacts with the O and Li atoms of the surface, that is, H atom bonds with O atoms of the surface while O atom bonds with the surface Li atoms due to the hydrogen bond effect. According to the different adsorption energies and vibrational frequencies of H2O, different adsorption types can be classified. These results may explain the origin of multiple desorption peaks in TDS experiments.

  11. Kinetics of T cell-activation molecules in response to Mycobacterium tuberculosis antigens

    Directory of Open Access Journals (Sweden)

    Antas Paulo RZ

    2002-01-01

    Full Text Available The phenotypic features acquired subsequent to antigen-specific stimulation in vitro were evaluated by means of the kinetic expressions of CD69 and CD25 activation molecules on T lymphocytes and assayed by flow cytometry in response to PPD, Ag85B, and ferritin in PPD-positive healthy control individuals. In response to PHA, CD69 staining on both CD4+ and CD8+ T cells became initially marked after 4 h, peaked at 24 h, and quickly decreased after 120 h. For CD25, a latter expression was detected around 8 h, having increased after 96 h. As expected, the response rate to the mycobacterial antigens was much lower than that to the mitogen. Positive staining was high after 96 h for CD25 and after 24 h for CD69. CD69 expression was significantly enhanced (p < 0.05 on CD8+ as compared to CD4+ T cells. High levels were also found between 96-120 h. Regarding Ag85B, CD25+ cells were mostly CD4+ instead of CD8+ T cells. Moreover, in response to ferritin, a lower CD25 expression was noted. The present data will allow further characterization of the immune response to new mycobacterial-specific antigens and their evaluation for possible inclusion in developing new diagnostic techniques for tuberculosis as well in a new vaccine to prevent the disease.

  12. Dimeric aluminum-phosphorus compounds as masked frustrated Lewis pairs for small molecule activation.

    Science.gov (United States)

    Roters, Steffi; Appelt, Christian; Westenberg, Hauke; Hepp, Alexander; Slootweg, J Chris; Lammertsma, Koop; Uhl, Werner

    2012-08-14

    Hydroalumination of aryldialkynylphosphines RP(C≡C-(t)Bu)(2) (R = Ph, Mes) with equimolar quantities of diethylaluminum hydride afforded mixed alkenyl-alkynyl cyclic dimers in which the dative aluminum-phosphorus bonds are geminal to the exocyclic alkenyl groups. Addition of triethylaluminum to isolated 1 (R = Ph) or to the in situ generated species (R = Mes) caused diethylaluminum ethynide elimination to yield the arylethylphosphorus dimers 2 and 3. These possess a chair-like Al(2)C(2)P(2) heterocycle with intermolecular Al-P interactions. The boat conformation (4) was obtained by the reaction of (t)Bu-P(C≡C-(t)Bu)(2) with di(tert-butyl)aluminum hydride. Despite being dimeric, 2 behaves as a frustrated Lewis pair and activates small molecules. The reaction with carbon dioxide gave cis/trans isomeric AlPC(2)O heterocycles that differ only by the configuration of the exocyclic alkenyl unit. Four isomers resulted from the reaction with phenyl isocyanate. This is caused by cis/trans isomerization of the initial C=O adduct and subsequent rearrangement to the AlPC(2)N heterocycle, being the C=N adduct.

  13. Evaluation of Activated Leukocyte Cell Adhesion Molecule as a Biomarker for Breast Cancer in Egyptian Patients

    International Nuclear Information System (INIS)

    El-Shepiny, M.S.E.M.

    2013-01-01

    In this study, serum activated leukocyte cell adhesion molecule (ALCAM) levels were evaluated in 41 primary breast cancer patients and 20 healthy females, and its diagnostic value was quantified, and compared with those of carbohydrate antigen 15-3 (CA15-3) and carcinoembryonic antigen (CEA). Also, its prognostic value was examined. Serum ALCAM levels were also evaluated before and after surgical treatment. Serum levels of ALCAM and CA 15-3 were significantly higher in breast cancer patients than healthy controls (P=0.002, P=0.043 respectively), but the difference in serum CEA levels did not reach statistical significance. Serum ALCAM levels had significant area under the curve (AUC) (P=0.002), but serum levels of CA 15-3 and CEA had nonsignificant AUCs, and various combinations between them did not result in any improvement. A significant association was found between serum levels of ALCAM and CEA with age and menopausal status in breast cancer patients. Non-significant difference was shown in serum levels of ALCAM, CA 15-3 and CEA before and after surgical treatment. In conclusion, this study suggests that serum ALCAM may represent a novel diagnostic bio marker for breast cancer

  14. Identification of 2-Cys Peroxiredoxin (BmTPx-2 as Antioxidant Active Molecule from Babesia microti

    Directory of Open Access Journals (Sweden)

    Xunan Hai

    2017-10-01

    Full Text Available Peroxiredoxins (Prxs are a family of antioxidant enzymes that reduce peroxides in the presence of thioredoxin, thioredoxin reductase, and nicotinamide adenine dinucleotide phosphate (NADPH to resist oxidative stress. In this study, we identified and isolated a 2-Cys Prx designated as ‘BmTPx-2’ from Babesia microti, with a full-length cDNA of 826 bp and an open reading frame of 756 bp, which encodes a 251-amino acid protein. BLAST analysis demonstrated that BmTPx-2 shows the typical features of members of the 2-Cys Prx family, which includes harboring two conserved VCP motifs with Cys101 and Cys221 conserved cysteine residues. Recombinant BmTPx-2 was expressed in Escherichia coli and analyzed by western blot. The antioxidant activity of BmTPx-2 was demonstrated using a mixed-function oxidation system and oxidation of NADPH. Furthermore, BmTPx-2 mRNA expression level in parasites at the erythrocytes and tick stages were analyzed by real-time fluorescence quantitative PCR. Peak BmTPx-2 mRNA transcription was detected 8 days after infection at the erythrocyte stage, but not at the tick stage. Taken together, this study characterized BmTPx-2 from B. microti as an antioxidant molecule that was specifically transcribed at the erythrocyte stage.

  15. Small-molecule MAPK inhibitors restore radioiodine incorporation in mouse thyroid cancers with conditional BRAF activation

    Science.gov (United States)

    Chakravarty, Debyani; Santos, Elmer; Ryder, Mabel; Knauf, Jeffrey A.; Liao, Xiao-Hui; West, Brian L.; Bollag, Gideon; Kolesnick, Richard; Thin, Tin Htwe; Rosen, Neal; Zanzonico, Pat; Larson, Steven M.; Refetoff, Samuel; Ghossein, Ronald; Fagin, James A.

    2011-01-01

    Advanced human thyroid cancers, particularly those that are refractory to treatment with radioiodine (RAI), have a high prevalence of BRAF (v-raf murine sarcoma viral oncogene homolog B1) mutations. However, the degree to which these cancers are dependent on BRAF expression is still unclear. To address this question, we generated mice expressing one of the most commonly detected BRAF mutations in human papillary thyroid carcinomas (BRAFV600E) in thyroid follicular cells in a doxycycline-inducible (dox-inducible) manner. Upon dox induction of BRAFV600E, the mice developed highly penetrant and poorly differentiated thyroid tumors. Discontinuation of dox extinguished BRAFV600E expression and reestablished thyroid follicular architecture and normal thyroid histology. Switching on BRAFV600E rapidly induced hypothyroidism and virtually abolished thyroid-specific gene expression and RAI incorporation, all of which were restored to near basal levels upon discontinuation of dox. Treatment of mice with these cancers with small molecule inhibitors of either MEK or mutant BRAF reduced their proliferative index and partially restored thyroid-specific gene expression. Strikingly, treatment with the MAPK pathway inhibitors rendered the tumor cells susceptible to a therapeutic dose of RAI. Our data show that thyroid tumors carrying BRAFV600E mutations are exquisitely dependent on the oncoprotein for viability and that genetic or pharmacological inhibition of its expression or activity is associated with tumor regression and restoration of RAI uptake in vivo in mice. These findings have potentially significant clinical ramifications. PMID:22105174

  16. Identification of an antioxidant small-molecule with broad-spectrum antiviral activity.

    Science.gov (United States)

    Panchal, Rekha G; Reid, St Patrick; Tran, Julie P; Bergeron, Alison A; Wells, Jay; Kota, Krishna P; Aman, Javad; Bavari, Sina

    2012-01-01

    The highly lethal filoviruses, Ebola and Marburg cause severe hemorrhagic fever in humans and non-human primates. To date there are no licensed vaccines or therapeutics to counter these infections. Identifying novel pathways and host targets that play an essential role during infection will provide potential targets to develop therapeutics. Small molecule chemical screening for Ebola virus inhibitors resulted in identification of a compound NSC 62914. The compound was found to exhibit anti-filovirus activity in cell-based assays and in vivo protected mice following challenge with Ebola or Marburg viruses. Additionally, the compound was found to inhibit Rift Valley fever virus, Lassa virus and Venezuelan equine encephalitis virus in cell-based assays. Investigation of the mechanism of action of the compound revealed that it had antioxidant properties. Specifically, compound NSC 62914 was found to act as a scavenger of reactive oxygen species, and to up-regulate oxidative stress-induced genes. However, four known antioxidant compounds failed to inhibit filovirus infection, thus suggesting that the mechanistic basis of the antiviral function of the antioxidant NSC 62914 may involve modulation of multiple signaling pathways/targets. Published by Elsevier B.V.

  17. Complement activating soluble pattern recognition molecules with collagen-like regions, mannan-binding lectin, ficolins and associated proteins

    DEFF Research Database (Denmark)

    Thiel, Steffen

    2007-01-01

    Mannan-binding lectin (MBL), L-ficolin, M-ficolin and H-ficolin are all complement activating soluble pattern recognition molecules with recognition domains linked to collagen-like regions. All four may form complexes with four structurally related proteins, the three MBL-associated serine...... proteases (MASPs), MASP-1, MASP-2 and MASP-3, and a smaller MBL-associated protein (MAp19). The four recognition molecules recognize patterns of carbohydrate or acetyl-group containing ligands. After binding to the relevant targets all four are able to activate the complement system. We thus have a system...... where four different and/or overlapping patterns of microbial origin or patterns of altered-self may be recognized, but in all cases the signalling molecules, the MASPs, are shared. MASP-1 and MASP-3 are formed from one gene, MASP1/3, by alternative splicing generating two different mRNAs from a single...

  18. Surface functionalization of bioactive glasses with natural molecules of biological significance, part II: Grafting of polyphenols extracted from grape skin

    Science.gov (United States)

    Zhang, Xin; Ferraris, Sara; Prenesti, Enrico; Verné, Enrica

    2013-12-01

    Polyphenols, as one of the most important family of phytochemicals protective substances from grape fruit, possess various biological activities and health-promoting benefits, for example: inhibition of some degenerative diseases, cardiovascular diseases and certain types of cancers, reduction of plasma oxidative stress and slowing aging. The combination of polyphenols and biomaterials may have good potential to reach good bioavailability and controlled release, as well as to give biological signaling properties to the biomaterial surfaces. In this research, conventional solvent extraction was developed for obtaining polyphenols from dry grape skins. The Folin&Ciocalteu method was used to determine the amount of total polyphenols in the extracts. Surface functionalization of two bioactive glasses (SCNA and CEL2) was performed by grafting the extracted polyphenols on their surfaces. The effectiveness of the functionalization was tested by UV spectroscopy, which analyzes the amount of polyphenols in the uptake solution (before and after functionalization) and on solid samples, and XPS, which analyzes the presence of phenols on the material surface.

  19. Hypercrosslinked large surface area porous polymer monoliths for hydrophilic interaction liquid chromatography of small molecules featuring zwitterionic functionalities attached to gold nanoparticles held in layered structure

    OpenAIRE

    Lv, Yongqin; Lin, Zhixing; Svec, Frantisek

    2012-01-01

    A novel approach to porous polymer monoliths hypercrosslinked to obtain large surface areas and modified with zwitterionic functionalities through the attachment of gold nanoparticles in a layered architecture has been developed. The capillary columns were used for the separation of small molecules in hydrophilic interaction liquid chromatography mode. First, a monolith with a very large surface area of 430 m2/g was prepared by hypercrosslinking from a generic poly(4-methylstyrene-co-vinylben...

  20. Mechanisms of transcriptional regulation and prognostic significance of activated leukocyte cell adhesion molecule in cancer

    Directory of Open Access Journals (Sweden)

    Chen Hairu

    2010-10-01

    Full Text Available Abstract Background Activated leukocyte cell adhesion molecule (ALCAM is implicated in the prognosis of multiple cancers with low level expression associated with metastasis and early death in breast cancer. Despite this significance, mechanisms that regulate ALCAM gene expression and ALCAM's role in adhesion of pre-metastatic circulating tumor cells have not been defined. We studied ALCAM expression in 20 tumor cell lines by real-time PCR, western blot and immunochemistry. Epigenetic alterations of the ALCAM promoter were assessed using methylation-specific PCR and bisulfite sequencing. ALCAM's role in adhesion of tumor cells to the vascular wall was studied in isolated perfused lungs. Results A common site for transcription initiation of the ALCAM gene was identified and the ALCAM promoter sequenced. The promoter contains multiple cis-active elements including a functional p65 NF-κB motif, and it harbors an extensive array of CpG residues highly methylated exclusively in ALCAM-negative tumor cells. These CpG residues were modestly demethylated after 5-aza-2-deoxycytidine treatment. Restoration of high-level ALCAM expression using an ALCAM cDNA increased clustering of MDA-MB-435 tumor cells perfused through the pulmonary vasculature of ventilated rat lungs. Anti-ALCAM antibodies reduced the number of intravascular tumor cell clusters. Conclusion Our data suggests that loss of ALCAM expression, due in part to DNA methylation of extensive segments of the promoter, significantly impairs the ability of circulating tumor cells to adhere to each other, and may therefore promote metastasis. These findings offer insight into the mechanisms for down-regulation of ALCAM gene expression in tumor cells, and for the positive prognostic value of high-level ALCAM in breast cancer.

  1. Sperm cell surface dynamics during activation and fertilization

    NARCIS (Netherlands)

    Boerke, A.|info:eu-repo/dai/nl/304822922

    2013-01-01

    Before the sperm cell can reach the oocyte it needs to be activated and to undergo a series of preparative steps. The sperm surface dynamics was studied in relation to this activation process and the modifications and removal of sperm surface components havebeen investigated. Bicarbonate-induced

  2. Temperature effects on surface activity and application in oxidation ...

    Indian Academy of Sciences (India)

    Keywords. Surface activity; cetyl trimethylammonium bromide; sodium dodecyl sulfate; temperature; oxidation. ... Catalytic effect on oxidation of toluene derivatives with potassium permanganate follows the order CTAB-SDS > SDS > CTAB. This is not caused by the dissociative effect of CTAB-SDS with low surface activity at ...

  3. An enzymatic deconjugation method for the analysis of small molecule active drugs on antibody-drug conjugates.

    Science.gov (United States)

    Li, Yi; Gu, Christine; Gruenhagen, Jason; Yehl, Peter; Chetwyn, Nik P; Medley, Colin D

    2016-01-01

    Antibody-drug conjugates (ADCs) are complex therapeutic agents that use the specific targeting properties of antibodies and the highly potent cytotoxicity of small molecule drugs to selectively eliminate tumor cells while limiting the toxicity to normal healthy tissues. Two critical quality attributes of ADCs are the purity and stability of the active small molecule drug linked to the ADC, but these are difficult to assess once the drug is conjugated to the antibody. In this study, we report a enzyme deconjugation approach to cleave small molecule drugs from ADCs, which allows the drugs to be subsequently characterized by reversed-phase high performance liquid chromatography. The model ADC we used in this study utilizes a valine-citrulline linker that is designed to be sensitive to endoproteases after internalization by tumor cells. We screened several proteases to determine the most effective enzyme. Among the 3 cysteine proteases evaluated, papain had the best efficiency in cleaving the small molecule drug from the model ADC. The deconjugation conditions were further optimized to achieve complete cleavage of the small molecule drug. This papain deconjugation approach demonstrated excellent specificity and precision. The purity and stability of the active drug on an ADC drug product was evaluated and the major degradation products of the active drug were identified. The papain deconjugation method was also applied to several other ADCs, with the results suggesting it could be applied generally to ADCs containing a valine-citrulline linker. Our results indicate that the papain deconjugation method is a powerful tool for characterizing the active small molecule drug conjugated to an ADC, and may be useful in ensuring the product quality, efficacy and the safety of ADCs.

  4. Activation of Relaxin Family Receptor 1 from different mammalian species by relaxin peptide and small molecule agonist ML290

    Directory of Open Access Journals (Sweden)

    Zaohua eHuang

    2015-08-01

    Full Text Available Relaxin peptide (RLN, which signals through the relaxin family peptide 1 (RXFP1 GPCR receptor, has shown therapeutic effects in an acute heart failure clinical trial. We have identified a small molecule agonist of human RXFP1, ML290; however, it does not activate the mouse receptor. To find a suitable animal model for ML290 testing and to gain mechanistic insights into the interaction of various ligands with RXFP1, we have cloned rhesus macaque, pig, rabbit, and guinea pig RXFP1s and analyzed their activation by RLN and ML290. HEK293T cells expressing macaque or pig RXFP1 responded to relaxin and ML290 treatment as measured by an increase of cAMP production. Guinea pig RXFP1 responded to relaxin but had very low response to ML290 treatment only at highest concentrations used. The rabbit RXFP1 amino acid sequence was the most divergent, with a number of unique substitutions within the ectodomain and the 7-transmembrane domain (7TM. Two splice variants of rabbit RXFP1 derived through alternative splicing of the forth exon were identified. In contrast to the other species, rabbit RXFP1s were activated by ML290, but not with human, pig, mouse, or rabbit relaxins. Using FLAG-tagged constructs, we have shown that both rabbit RXFP1 variants are expressed on the cell surface. No binding of human Eu-labeled relaxin to rabbit RXFP1 was detected, suggesting that in this species RXFP1 might be non-functional. We used chimeric rabbit-human and guinea pig-human constructs to identify regions important for RLN or ML290 receptor activation. Chimeras with the human ectodomain and rabbit 7TM domain were activated by RLN, whereas substitution of part of the guinea pig 7TM domain with the human sequence only partially restored ML290 activation, confirming the allosteric mode of action for the two ligands. Our data demonstrate that macaque and pig models can be used for ML290 testing.

  5. Coordinated surface activities in Variovorax paradoxus EPS

    Directory of Open Access Journals (Sweden)

    Gregory Glenn A

    2009-06-01

    Full Text Available Abstract Background Variovorax paradoxus is an aerobic soil bacterium frequently associated with important biodegradative processes in nature. Our group has cultivated a mucoid strain of Variovorax paradoxus for study as a model of bacterial development and response to environmental conditions. Colonies of this organism vary widely in appearance depending on agar plate type. Results Surface motility was observed on minimal defined agar plates with 0.5% agarose, similar in nature to swarming motility identified in Pseudomonas aeruginosa PAO1. We examined this motility under several culture conditions, including inhibition of flagellar motility using Congo Red. We demonstrated that the presence of a wetting agent, mineral, and nutrient content of the media altered the swarming phenotype. We also demonstrated that the wetting agent reduces the surface tension of the agar. We were able to directly observe the presence of the wetting agent in the presence and absence of Congo Red, and found that incubation in a humidified chamber inhibited the production of wetting agent, and also slowed the progression of the swarming colony. We observed that swarming was related to both carbon and nitrogen sources, as well as mineral salts base. The phosphate concentration of the mineral base was critical for growth and swarming on glucose, but not succinate. Swarming on other carbon sources was generally only observed using M9 salts mineral base. Rapid swarming was observed on malic acid, d-sorbitol, casamino acids, and succinate. Swarming at a lower but still detectable rate was observed on glucose and sucrose, with weak swarming on maltose. Nitrogen source tests using succinate as carbon source demonstrated two distinct forms of swarming, with very different macroscopic swarm characteristics. Rapid swarming was observed when ammonium ion was provided as nitrogen source, as well as when histidine, tryptophan, or glycine was provided. Slower swarming was observed

  6. Radioimmunoassay for platelet activation specific protein GMP-140 on the platelet surface and in plasma

    International Nuclear Information System (INIS)

    Wu Guoxin; Li Jianyong; Ruan Changgeng

    1991-08-01

    Using monoclonal antibody (McAb) SZ-51 which is specific for an alpha-granule membrane protein (GMP-140) on the surface of human activated platelets, the platelet GMP-140 expression in fixed whole blood was measured by direct radioimmunoassay and GMP-140 microparticles in plasma was measured by sandwich method. The GMP-140 molecules per platelet or milliliter (mL) were calculated for the following subjects; acute myocardial infarction; cerebro thrombosis; diabetic mellitus; asthma attack; epidemic hemorrhagic fever etc.. By comparing with the concentration of thromboxane B 2 (TXB 2 ) and von Willebrand factor (vWF) in plasma, it is confirmed that the measurement of GMP-140 molecules is better than that of TXB 2 and vWF. It is a sensitive and specific method for evaluating the platelet activation degree in vivo. The establishment of this method will be useful to diagnosing the thrombotic disorders and studying the pathogenesis of some other diseases

  7. Activation and adsorption of CO{sub 2} on copper surfaces and clusters

    Energy Technology Data Exchange (ETDEWEB)

    Gautam, Seema; Dharmvir, Keya, E-mail: keya@pu.ac.in [Department of Physics, Center of Advanced Studies, Panjab University, Chandigarh- 160014 (India); Goel, Neetu [Department of Chemistry, Center of Advanced Studies, Panjab University, Chandigarh-160014 (India)

    2014-04-24

    The activation and adsorption of CO{sub 2} over Cu{sub n} clusters have been investigated by first principle calculations. Results of these calculations are compared with the previous studies of adsorption of CO{sub 2} on Cu (hkl) surfaces [Wang et al. Surface Science 570 (2004) 205–217]. We find that CO{sub 2} is preferentially adsorbed over the clusters in comparison with Cu (hkl) surfaces. The Cu13 cluster in particular dissociates the CO{sub 2} molecule adsorbed on the one of the caps of the icosahedron into CO and atomic oxygen. This activated configuration can act as a precursor to reactions leading to hydrocarbon fuels from CO{sub 2}.

  8. Neurite outgrowth induced by a synthetic peptide ligand of neural cell adhesion molecule requires fibroblast growth factor receptor activation

    DEFF Research Database (Denmark)

    Rønn, L C; Doherty, P; Holm, A

    2000-01-01

    The neural cell adhesion molecule NCAM is involved in axonal outgrowth and target recognition in the developing nervous system. In vitro, NCAM-NCAM binding has been shown to induce neurite outgrowth, presumably through an activation of fibroblast growth factor receptors (FGFRs). We have recently...

  9. The endothelial adaptor molecule TSAd is required for VEGF-induced angiogenic sprouting through junctional c-Src activation

    NARCIS (Netherlands)

    Gordon, Emma J; Fukuhara, Daisuke; Weström, Simone; Padhan, Narendra; Sjöström, Elisabet O; van Meeteren, Laurens; He, Liqun; Orsenigo, Fabrizio; Dejana, Elisabetta; Bentley, Katie; Spurkland, Anne; Claesson-Welsh, Lena

    2016-01-01

    Activation of vascular endothelial growth factor (VEGF) receptor 2 (VEGFR2) by VEGF binding is critical for vascular morphogenesis. In addition, VEGF disrupts the endothelial barrier by triggering the phosphorylation and turnover of the junctional molecule VE-cadherin, a process mediated by the

  10. Differing activation status and immune effector molecule expression profiles of neonatal and maternal lymphocytes in an African population.

    NARCIS (Netherlands)

    Engelmann, I.; Moeller, U.; Santamaria, A.; Kremsner, P.G.; Luty, A.J.F.

    2006-01-01

    Higher susceptibility of newborns to infections has been attributed to the hypo-responsiveness of their cellular immune system. Here we compared the activation status and expression of cytokines and cytotoxic molecules of cord versus maternal peripheral blood mononuclear cells in an African

  11. Designing active template molecules by combining computational de novo design and human chemist's expertise.

    Science.gov (United States)

    Lameijer, Eric-Wubbo; Tromp, Reynier A; Spanjersberg, Ronald F; Brussee, Johannes; Ijzerman, Adriaan P

    2007-04-19

    We used a new software tool for de novo design, the "Molecule Evoluator", to generate a number of small molecules. Explicit constraints were a relatively low molecular weight and otherwise limited functionality, for example, low numbers of hydrogen bond donors and acceptors, one or two aromatic rings, and a small number of rotatable bonds. In this way, we obtained a collection of scaffold- or templatelike molecules rather than fully "decorated" ones. We asked medicinal chemists to evaluate the suggested molecules for ease of synthesis and overall appeal, allowing them to make structural changes to the molecules for these reasons. On the basis of their recommendations, we synthesized eight molecules with an unprecedented (not patented) yet simple structure, which were subsequently tested in a screen of 83 drug targets, mostly G protein-coupled receptors. Four compounds showed affinity for biogenic amine targets (receptor, ion channel, and transport protein), reflecting the training of the medicinal chemists involved. Apparently the generation of leadlike solutions helped the medicinal chemists to select good starting points for future lead optimization, away from existing compound libraries.

  12. Machine learning models identify molecules active against the Ebola virus in vitro [version 3; referees: 2 approved

    Directory of Open Access Journals (Sweden)

    Sean Ekins

    2017-01-01

    Full Text Available The search for small molecule inhibitors of Ebola virus (EBOV has led to several high throughput screens over the past 3 years. These have identified a range of FDA-approved active pharmaceutical ingredients (APIs with anti-EBOV activity in vitro and several of which are also active in a mouse infection model. There are millions of additional commercially-available molecules that could be screened for potential activities as anti-EBOV compounds. One way to prioritize compounds for testing is to generate computational models based on the high throughput screening data and then virtually screen compound libraries. In the current study, we have generated Bayesian machine learning models with viral pseudotype entry assay and the EBOV replication assay data. We have validated the models internally and externally. We have also used these models to computationally score the MicroSource library of drugs to select those likely to be potential inhibitors. Three of the highest scoring molecules that were not in the model training sets, quinacrine, pyronaridine and tilorone, were tested in vitro and had EC50 values of 350, 420 and 230 nM, respectively. Pyronaridine is a component of a combination therapy for malaria that was recently approved by the European Medicines Agency, which may make it more readily accessible for clinical testing. Like other known antimalarial drugs active against EBOV, it shares the 4-aminoquinoline scaffold. Tilorone, is an investigational antiviral agent that has shown a broad array of biological activities including cell growth inhibition in cancer cells, antifibrotic properties, α7 nicotinic receptor agonist activity, radioprotective activity and activation of hypoxia inducible factor-1. Quinacrine is an antimalarial but also has use as an anthelmintic. Our results suggest data sets with less than 1,000 molecules can produce validated machine learning models that can in turn be utilized to identify novel EBOV inhibitors in

  13. Machine learning models identify molecules active against the Ebola virus in vitro [version 1; referees: 2 approved

    Directory of Open Access Journals (Sweden)

    Sean Ekins

    2015-10-01

    Full Text Available The search for small molecule inhibitors of Ebola virus (EBOV has led to several high throughput screens over the past 3 years. These have identified a range of FDA-approved active pharmaceutical ingredients (APIs with anti-EBOV activity in vitro and several of which are also active in a mouse infection model. There are millions of additional commercially-available molecules that could be screened for potential activities as anti-EBOV compounds. One way to prioritize compounds for testing is to generate computational models based on the high throughput screening data and then virtually screen compound libraries. In the current study, we have generated Bayesian machine learning models with viral pseudotype entry assay and the EBOV replication assay data. We have validated the models internally and externally. We have also used these models to computationally score the MicroSource library of drugs to select those likely to be potential inhibitors. Three of the highest scoring molecules that were not in the model training sets, quinacrine, pyronaridine and tilorone, were tested in vitro and had EC50 values of 350, 420 and 230 nM, respectively. Pyronaridine is a component of a combination therapy for malaria that was recently approved by the European Medicines Agency, which may make it more readily accessible for clinical testing. Like other known antimalarial drugs active against EBOV, it shares the 4-aminoquinoline scaffold. Tilorone, is an investigational antiviral agent that has shown a broad array of biological activities including cell growth inhibition in cancer cells, antifibrotic properties, α7 nicotinic receptor agonist activity, radioprotective activity and activation of hypoxia inducible factor-1. Quinacrine is an antimalarial but also has use as an anthelmintic. Our results suggest data sets with less than 1,000 molecules can produce validated machine learning models that can in turn be utilized to identify novel EBOV inhibitors in

  14. Serum activated leukocyte cell adhesion molecule and intercellular adhesion molecule-1 in patients with gastric cancer: Can they be used as biomarkers?

    Science.gov (United States)

    Erturk, Kayhan; Tastekin, Didem; Bilgin, Elif; Serilmez, Murat; Bozbey, Hamza Ugur; Sakar, Burak

    2016-02-01

    Cellular adhesion molecules might be used as markers in diagnosis and prognosis in some types of malignant tumors. The purpose of this study was to determine the clinical significance of the serum levels of activated leukocyte cell adhesion molecule-1 (ALCAM) and intercellular adhesion molecule-1 (ICAM-1) in gastric cancer (GC) patients. Fifty-eight GC patients and 20 age- and sex-matched healthy controls were enrolled into this study. Pretreatment serum markers were determined by the solid-phase sandwich enzyme-linked immunosorbent assay (ELISA). The median age at diagnosis was 59.5 years (range 32-82 years). Tumor localizations of the majority of the patients were antrum (n=42, 72.4%) and tumor histopathologies of the majority of the patients were diffuse (n=43, 74.1%). The majority of the patients had stage IV disease (n=41, 70.7%). Thirty six (62.1%) patients had lymph node involvement. The median follow-up time was 66 months (range 1-97.2 months). At the end of the observation period, 26 patients (44.8%) were dead. The median survival for all patients was 21.4±5 months (%95 CI, 11.5-31.3). The 1-year survival rates were 66.2%. The baseline serum ALCAM levels of the patients were significantly higher than those of the controls (p=0.001). There was no significant difference in the serum levels of ICAM-1 between the patients and controls (p=0.232). No significant correlation was detected between the levels of the serum markers and other clinical parameters (p>0.05). Tumor localization (p=0.03), histopathology (p=0.05), and response to chemotherapy (p=0.003) had prognostic factors on survival. Neither serum ALCAM levels nor serum ICAM-1 levels were identified to have a prognostic role on overall survival (ICAM-1 p=0.6, ALCAM p=0.25). In conclusion, serum levels of ALCAM were found to have diagnostic value in GC patients. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

  15. Non-adiabatic effects within a single thermally averaged potential energy surface: thermal expansion and reaction rates of small molecules.

    Science.gov (United States)

    Alonso, J L; Castro, A; Clemente-Gallardo, J; Echenique, P; Mazo, J J; Polo, V; Rubio, A; Zueco, D

    2012-12-14

    At non-zero temperature and when a system has low-lying excited electronic states, the ground-state Born-Oppenheimer approximation breaks down and the low-lying electronic states are involved in any chemical process. In this work, we use a temperature-dependent effective potential for the nuclei which can accommodate the influence of an arbitrary number of electronic states in a simple way, while at the same time producing the correct Boltzmann equilibrium distribution for the electronic part. With the help of this effective potential, we show that thermally activated low-lying electronic states can have a significant effect in molecular properties for which electronic excitations are oftentimes ignored. We study the thermal expansion of the Manganese dimer, Mn(2), where we find that the average bond length experiences a change larger than the present experimental accuracy upon the inclusion of the excited states into the picture. We also show that, when these states are taken into account, reaction-rate constants are modified. In particular, we study the opening of the ozone molecule, O(3), and show that in this case the rate is modified as much as a 20% with respect to the ground-state Born-Oppenheimer prediction.

  16. Effect of methylprednisolone on the oxidative burst activity, adhesion molecules and clinical outcome following open heart surgery

    DEFF Research Database (Denmark)

    Toft, P; Christiansen, K; Tønnesen, Else Kirstine

    1997-01-01

    Following cardiac surgery with cardiopulmonary bypass (CPB), activated granulocytes may be involved with ischaemia/ reperfusion injury. The purpose of this study was to investigate whether steroids could reduce the oxidative burst activity of granulocytes, the expression of adhesion molecules...... and the control group regarding the expression of adhesion molecules or the oxidative burst activity. In the steroid group the fluid gain during extracorporeal circulation (ECC) was 683 ml (median) compared to 1488 ml in the control group. Steroids prevented hyperthermia in the postoperative period but did...... not improve the weaning from the ventilator or reduce the stay in the intensive-care unit. In conclusion, treatment with steroids prevented hyperthermia following open heart surgery with CPB and reduced capillary leak during ECC. Methylprednisolone, however, did not reduce the oxidative burst activity...

  17. Sorption Characteristics of Mixed Molecules of Glutaraldehyde from Water on Mesoporous Acid-Amine Modified Low-Cost Activated Carbon: Mechanism, Isotherm, and Kinetics

    Directory of Open Access Journals (Sweden)

    Mukosha Lloyd

    2015-01-01

    Full Text Available The environmental discharge of inefficiently treated waste solutions of the strong biocide glutaraldehyde (GA from hospitals has potential toxic impact on aquatic organisms. The adsorption characteristics of mixed polarized monomeric and polymeric molecules of GA from water on mesoporous acid-amine modified low-cost activated carbon (AC were investigated. It was found that the adsorption strongly depended on pH and surface chemistry. In acidic pH, the adsorption mechanism was elaborated to involve chemical sorption of mainly hydroxyl GA monomeric molecules on acidic surface groups, while in alkaline pH, the adsorption was elaborated to involve both chemical and physical sorption of GA polymeric forms having mixed functional groups (aldehyde, carboxyl, and hydroxyl on acidic and amine surface groups. The optimum pH of adsorption was about 12 with significant contribution by cooperative adsorption, elucidated in terms of hydrogen bonding and aldol condensation. Freundlich and Dubinin-Radushkevich models were fitted to isotherm data. The adsorption kinetics was dependent on initial concentration and temperature and described by the Elovich model. The adsorption was endothermic, while the intraparticle diffusion model suggested significant contribution by film diffusion. The developed low-cost AC could be used to supplement the GA alkaline deactivation process for efficient removal of residual GA aquatic toxicity.

  18. Active Surface Compensation for Large Radio Telescope Antennas

    Science.gov (United States)

    Wang, Congsi; Li, Haihua; Ying, Kang; Xu, Qian; Wang, Na; Duan, Baoyan; Gao, Wei; Xiao, Lan; Duan, Yuhu

    2018-03-01

    With the development of radio telescope antennas with large apertures, high gain, and wide frequency bands, compensation methods, such as mechanical or electronic compensation, are obviously essential to ensure the electrical performance of antennas that work in complex environments. Since traditional compensation methods can only adjust antenna pointing but not the surface accuracy, which are limited for obtaining high surface precision and aperture efficiency, active surface adjustment has become an indispensable tool in this field. Therefore, the development process of electrical performance compensation methods for radio telescope antennas is introduced. Further, a series of analyses of the five key technologies of active surface adjustment is presented. Then, four typical large antennas that have been designed with active main reflector technology are presented and compared. Finally, future research directions and suggestions for reflector antenna compensation method! s based on active surface adjustment are presented.

  19. Phosphate Activation via Reduced Oxidation State Phosphorus (P. Mild Routes to Condensed-P Energy Currency Molecules

    Directory of Open Access Journals (Sweden)

    Claire R. Cousins

    2013-07-01

    Full Text Available The emergence of mechanisms for phosphorylating organic and inorganic molecules is a key step en route to the earliest living systems. At the heart of all contemporary biochemical systems reside reactive phosphorus (P molecules (such as adenosine triphosphate, ATP as energy currency molecules to drive endergonic metabolic processes and it has been proposed that a predecessor of such molecules could have been pyrophosphate [P2O74−; PPi(V]. Arguably the most geologically plausible route to PPi(V is dehydration of orthophosphate, Pi(V, normally a highly endergonic process in the absence of mechanisms for activating Pi(V. One possible solution to this problem recognizes the presence of reactive-P containing mineral phases, such as schreibersite [(Fe,Ni3P] within meteorites whose abundance on the early Earth would likely have been significant during a putative Hadean-Archean heavy bombardment. Here, we propose that the reduced oxidation state P-oxyacid, H-phosphite [HPO32−; Pi(III] could have activated Pi(V towards condensation via the intermediacy of the condensed oxyacid pyrophosphite [H2P2O52−; PPi(III]. We provide geologically plausible provenance for PPi(III along with evidence of its ability to activate Pi(V towards PPi(V formation under mild conditions (80 °C in water.

  20. Structure determination of disordered organic molecules on surfaces from the Bragg spots of low-energy electron diffraction and total energy calculations

    International Nuclear Information System (INIS)

    Poon, H.C.; Weinert, M.; Saldin, D.K.; Stacchiola, D.; Zheng, T.; Tysoe, W.T.

    2004-01-01

    We show that an analysis of the intensity versus energy variation of Bragg spots due to low-energy electron diffraction from a disordered overlayer of molecules on a crystal surface allows a much more convenient method of determining the local adsorption geometries of such molecules than previously analyzed weak diffuse diffraction patterns. For the case of methanol on Pd(111), we show that the geometry determined by this means from experimental diffraction data is in excellent agreement with the predictions of density functional total energy calculations

  1. Bacteria-induced neo-biosynthesis, stabilization, and surface expression of functional class I molecules in mouse dendritic cells

    OpenAIRE

    Rescigno, Maria; Citterio, Stefania; Thèry, Clotilde; Rittig, Michael; Medaglini, Donata; Pozzi, Gianni; Amigorena, Sebastian; Ricciardi-Castagnoli, Paola

    1998-01-01

    Here, we show that bacteria induce de novo synthesis of both major histocompatability complex (MHC) class I and II molecules in a mouse dendritic cell culture system. The neo-biosynthesis of MHC class I molecules is delayed as compared with that of MHC class II. Furthermore, bacteria stabilize MHC class I molecules by a 3-fold increase of their half-life. This has important consequences for the capacity of dendritic cells to present bacterial antigens in the draining lymph nodes. In addition,...

  2. Conformational, spectroscopic and nonlinear optical properties of biologically active N,N-dimethyltryptamine molecule: a theoretical study.

    Science.gov (United States)

    Öner, Nazmiye; Tamer, Ömer; Avcı, Davut; Atalay, Yusuf

    2014-12-10

    The effective psychoactive properties of N,N-dimethyltryptamine (DMT) known as the near-death molecule have encouraged the imagination of many research disciplines for several decades. Although there is no theoretical study, a number of paper composed by experimental techniques have been reported for DMT molecule. In this study, the molecular modeling of DMT was carried out using B3LYP and HSEh1PBE levels of density functional theory (DFT). Our calculations showed that the energy gap between HOMO and LUMO is low, demonstrating that DMT is a biologically active molecule. Large hyperconjugation interaction energies imply that molecular charge transfer occurs in DMT. Moreover, NLO analysis indicates that DMT can be used an effective NLO material. Copyright © 2014 Elsevier B.V. All rights reserved.

  3. Acid-base characteristics of powdered-activated-carbon surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Reed, B.E. (West Virginia Univ., Morgantown (United States)); Jensen, J.N.; Matsumoto, M.R. (State Univ. of New York, Buffalo (United States))

    Adsorption of heavy metals onto activated carbon has been described using the surface-complex-formation (SCF) model, a chemical equilibrium model. The SCF model requires a knowledge of the amphoteric nature of activated carbon prior to metal adsorption modeling. In the past, a single-diprotic-acid-site model had been employed to describe the amphoteric nature of activated-carbon surfaces. During this study, the amphoteric nature of two powdered activated carbons were investigated, and a three-monoprotic site surface model was found to be a plausible alternative. The single-diprotic-acid-site and two-monoprotic-site models did not describe the acid-base behavior of the two carbons studied adequately. The two-diprotic site was acceptable for only one of the study carbons. The acid-base behavior of activated carbon surfaces seem to be best modeled as a series of weak monoprotic acids.

  4. Supramolecular self-assembly on the B-Si(111)-(√3x√3) R30° surface: From single molecules to multicomponent networks

    Science.gov (United States)

    Makoudi, Younes; Jeannoutot, Judicaël; Palmino, Frank; Chérioux, Frédéric; Copie, Guillaume; Krzeminski, Christophe; Cleri, Fabrizio; Grandidier, Bruno

    2017-09-01

    Understanding the physical and chemical processes in which local interactions lead to ordered structures is of particular relevance to the realization of supramolecular architectures on surfaces. While spectacular patterns have been demonstrated on metal surfaces, there have been fewer studies of the spontaneous organization of supramolecular networks on semiconductor surfaces, where the formation of covalent bonds between organics and adatoms usually hamper the diffusion of molecules and their subsequent interactions with each other. However, the saturation of the dangling bonds at a semiconductor surface is known to make them inert and offers a unique way for the engineering of molecular patterns on these surfaces. This review describes the physicochemical properties of the passivated B-Si(111)-(√3x√3) R30° surface, that enable the self-assembly of molecules into a rich variety of extended and regular structures on silicon. Particular attention is given to computational methods based on multi-scale simulations that allow to rationalize the relative contribution of the dispersion forces involved in the self-assembled networks observed with scanning tunneling microscopy. A summary of state of the art studies, where a fine tuning of the molecular network topology has been achieved, sheds light on new frontiers for exploiting the construction of supramolecular structures on semiconductor surfaces.

  5. Surface coverage dictates the surface bio-activity of D-amino acid oxidase.

    Science.gov (United States)

    Herrera, Elisa; Giacomelli, Carla E

    2014-05-01

    This work presents a systematic study on the relationship between the adsorption mechanism and the surface bio-activity of D-amino acid oxidase (pkDAAO). This rational approach is based on measuring the characteristic filling and relaxation times under different experimental conditions. With such a goal, real-time adsorption-desorption experiments at different degrees of surface coverage were performed tuning the electrostatic and hydrophobic interactions by changing the pH condition for the adsorption and the substrate properties (silica or gold). Surface bio-activity was measured in situ by amperometry using the bio-functional surface as the working electrode and ex situ by spectrophotometry. On both solid substrates, pkDAAO adsorption is a transport-controlled process, even under unfavorable electrostatic interactions (charged protein and substrate with the same sign) due to the high percentage of basic amino acids in the enzyme. On silica, the relaxation step is electrostatic in nature and occurs in the same time-scale as filling the surface when the substrate and the enzyme are oppositely charged at low surface coverage. Under unfavorable electrostatic conditions, the relaxation (if any) occurs at long time. Accordingly, the bio-activity of the native pkDAAO is preserved at any surface coverage. On gold, this step is driven by hydrophobic interactions (pH-independent) and the surface bio-activity is highly dependent on the degree of surface coverage. Under these conditions, the surface bio-activity is preserved only at high surfaces coverage. Our results clearly indicate that pkDAAO bio-functionalized surfaces cannot be coupled to amperometry because the analyte interferes the electrochemical signal. However, this simple bio-functionalized strategy can be joined to other detection methods. Copyright © 2014 Elsevier B.V. All rights reserved.

  6. Fibroblast adhesion and activation onto micro-machined titanium surfaces.

    Science.gov (United States)

    Guillem-Marti, J; Delgado, L; Godoy-Gallardo, M; Pegueroles, M; Herrero, M; Gil, F J

    2013-07-01

    Surface modifications performed at the neck of dental implants, in the manner of micro-grooved surfaces, can reduce fibrous tissue encapsulation and prevent bacterial colonization, thereby improving fibrointegration and the formation of a biological seal. However, the applied procedures are technically complex and/or time consuming methods. The aim of this study was to analyse the fibroblast behaviour on modified titanium surfaces obtained, applying a simple and low-cost method. An array of titanium surfaces was obtained using a commercial computerized numerical control lathe, modifying the feed rate and the cutting depth. To elucidate the potential ability of the generated surfaces to activate connective tissue cells, a thorough gene (by real time - qPCR) and protein (by western blot or zymography) expression and cellular response characterization (cell morphology, cell adhesion and cell activation by secreting extracellular matrix (ECM) components and their enzyme regulators) was performed. Micro-grooved surfaces have statistically significant differences in the groove's width (approximately 10, 50 and 100 μm) depending on the applied advancing fixed speed. Field emission scanning electron microscopy images showed that fibroblasts oriented along the generated grooves, but they were only entirely accommodated on the wider grooves (≥50 μm). Micro-grooved surfaces exhibited an earlier cell attachment and activation, as seen by collagen Iα1 and fibronectin deposition and activation of ECM remodelling enzymes, compared with the other surfaces. However, fibroblasts could remain in an activated state on narrower surfaces (micro-grooved surfaces could improve implant integration at the gingival site with respect to polished surfaces. Micro-grooved surfaces enhance early fibroblast adhesion and activation, which could be critical for the formation of a biological seal and finally promote tissue integration. Surfaces with wider grooves (≥50 μm) seem to be more

  7. Novel Schiff-base molecules as efficient corrosion inhibitors for mild steel surface in 1 M HCl medium: experimental and theoretical approach.

    Science.gov (United States)

    Saha, Sourav Kr; Dutta, Alokdut; Ghosh, Pritam; Sukul, Dipankar; Banerjee, Priyabrata

    2016-07-21

    In order to evaluate the effect of the functional group present in the ligand backbone towards corrosion inhibition performances, three Schiff-base molecules namely, (E)-4-((2-(2,4-dinitrophenyl)hydrazono)methyl)pyridine (L(1)), (E)-4-(2-(pyridin-4-ylmethylene)hydrazinyl)benzonitrile (L(2)) and (E)-4-((2-(2,4-dinitrophenyl)hydrazono)methyl)phenol (L(3)) were synthesized and used as corrosion inhibitors on mild steel in 1 M HCl medium. The corrosion inhibition effectiveness of the studied inhibitors was investigated by weight loss and several sophisticated analytical tools such as potentiodynamic polarization and electrochemical impedance spectroscopy measurements. Experimentally obtained results revealed that corrosion inhibition efficiencies followed the sequence: L(3) > L(1) > L(2). Electrochemical findings showed that inhibitors impart high resistance towards charge transfer across the metal-electrolyte interface and behaved as mixed type inhibitors. Scanning electron microscopy (SEM) was also employed to examine the protective film formed on the mild steel surface. The adsorption as well as inhibition ability of the inhibitor molecules on the mild steel surface was investigated by quantum chemical calculation and molecular dynamic (MD) simulation. In quantum chemical calculations, geometry optimized structures of the Schiff-base inhibitors, electron density distribution in HOMO and LUMO and Fukui indices of each atom were employed for their possible mode of interaction with the mild steel surfaces. MD simulations revealed that all the inhibitors molecules adsorbed in parallel orientation with respect to the Fe(110) surface.

  8. Adsorption of small molecules at the cobalt-doped SrTiO3(001) surface: A first-principles investigation

    Science.gov (United States)

    Carlotto, Silvia; Natile, Marta Maria; Glisenti, Antonella; Vittadini, Andrea

    2015-03-01

    The cobalt-doped SrTiO3 (001) surface and its interaction with small molecules (CO, NO and O2) is investigated by DFT and DFT + U calculations. Structural, electronic, and chemical changes induced by the presence of the cobalt impurity are studied. Similar to what is found for the bulk SrTiO3, cobalt impurities promote the formation of oxygen vacancies and tend to cluster with them. The presence of impurities has a strong influence on adsorption and in particular it gives rise i) to an enhancement of the adsorption energies and ii) to an inversion of the π electron flux from a surfacemolecule to a moleculesurface donation. Furthermore, the examined molecular probes have different affinities with surface defects/impurities: whereas the vacancy site is favored for O2and CO, NO is preferentially adsorbed at the Co impurity site. The obtained results provide the basis for further studies of the catalytic properties of Co-doped SrTiO3.

  9. Genome-Scale Architecture of Small Molecule Regulatory Networks and the Fundamental Trade-Off between Regulation and Enzymatic Activity.

    Science.gov (United States)

    Reznik, Ed; Christodoulou, Dimitris; Goldford, Joshua E; Briars, Emma; Sauer, Uwe; Segrè, Daniel; Noor, Elad

    2017-09-12

    Metabolic flux is in part regulated by endogenous small molecules that modulate the catalytic activity of an enzyme, e.g., allosteric inhibition. In contrast to transcriptional regulation of enzymes, technical limitations have hindered the production of a genome-scale atlas of small molecule-enzyme regulatory interactions. Here, we develop a framework leveraging the vast, but fragmented, biochemical literature to reconstruct and analyze the small molecule regulatory network (SMRN) of the model organism Escherichia coli, including the primary metabolite regulators and enzyme targets. Using metabolic control analysis, we prove a fundamental trade-off between regulation and enzymatic activity, and we combine it with metabolomic measurements and the SMRN to make inferences on the sensitivity of enzymes to their regulators. Generalizing the analysis to other organisms, we identify highly conserved regulatory interactions across evolutionarily divergent species, further emphasizing a critical role for small molecule interactions in the maintenance of metabolic homeostasis. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

  10. Ground-state kinetics of bistable redox-active donor-acceptor mechanically interlocked molecules.

    Science.gov (United States)

    Fahrenbach, Albert C; Bruns, Carson J; Li, Hao; Trabolsi, Ali; Coskun, Ali; Stoddart, J Fraser

    2014-02-18

    The ability to design and confer control over the kinetics of theprocesses involved in the mechanisms of artificial molecular machines is at the heart of the challenge to create ones that can carry out useful work on their environment, just as Nature is wont to do. As one of the more promising forerunners of prototypical artificial molecular machines, chemists have developed bistable redox-active donor-acceptor mechanically interlocked molecules (MIMs) over the past couple of decades. These bistable MIMs generally come in the form of [2]rotaxanes, molecular compounds that constitute a ring mechanically interlocked around a dumbbell-shaped component, or [2]catenanes, which are composed of two mechanically interlocked rings. As a result of their interlocked nature, bistable MIMs possess the inherent propensity to express controllable intramolecular, large-amplitude, and reversible motions in response to redox stimuli. In this Account, we rationalize the kinetic behavior in the ground state for a large assortment of these types of bistable MIMs, including both rotaxanes and catenanes. These structures have proven useful in a variety of applications ranging from drug delivery to molecular electronic devices. These bistable donor-acceptor MIMs can switch between two different isomeric states. The favored isomer, known as the ground-state co-conformation (GSCC) is in equilibrium with the less favored metastable state co-conformation (MSCC). The forward (kf) and backward (kb) rate constants associated with this ground-state equilibrium are intimately connected to each other through the ground-state distribution constant, KGS. Knowing the rate constants that govern the kinetics and bring about the equilibration between the MSCC and GSCC, allows researchers to understand the operation of these bistable MIMs in a device setting and apply them toward the construction of artificial molecular machines. The three biggest influences on the ground-state rate constants arise from

  11. Dynamics of cyanophenyl alkylbenzoate molecules in the bulk and in a surface layer adsorbed onto aerosil. Variation of the lengths of the alkyl chain

    Energy Technology Data Exchange (ETDEWEB)

    Frunza, Stefan [National Institute of Materials Physics, R-077125 Magurele (Romania); Schoenhals, Andreas [BAM Federal Institute of Materials Research and Testing, D-12205 Berlin (Germany); Frunza, Ligia, E-mail: lfrunza@infim.ro [National Institute of Materials Physics, R-077125 Magurele (Romania); Beica, Traian; Zgura, Irina; Ganea, Paul [National Institute of Materials Physics, R-077125 Magurele (Romania); Stoenescu, Daniel [Telecom-Bretagne, Departement d' Optique, Technopole Brest-Iroise 29238 Cedex (France)

    2010-06-16

    Graphical abstract: The temperature dependence of the molecular mobility in composites shows an Arrhenius-type regime at low temperature and a glassy-type one at higher temperature separated by a crossover phenomenon. - Abstract: The molecular mobility of 4-butyl- and 4-pentyl-4'-cyanophenyl benzoate (CP4B, CP5B) and their composites prepared from aerosil A380 was investigated by broadband dielectric spectroscopy in a large temperature range. Thermogravimetric and infrared investigations were additionally performed. High silica density (larger than 7 g aerosil/1 g of liquid crystal) was selected to observe a thin layer adsorbed on the surface of the silica particles. The data were compared with those of the member of the series with six carbon atoms in the alkyl tail. Bulk CP4B and CP5B show the dielectric behaviour expected for liquid crystals. For the composites one relaxation process is observed at frequencies much lower than those for the corresponding bulk, which was assigned to the dynamics of the molecules in a surface layer. The temperature dependence of the relaxation rates (and of the dielectric strength) shows a crossover behaviour with two distinguished regimes. At higher temperatures the data obey the Vogel-Fulcher-Tammann law, whereas an Arrhenius law is observed at lower temperature, in a close similarity to the behaviour of a constrained dynamic glass transition. The estimated Vogel and crossover temperature is independent on the tail length, while the activation energy for the low temperature branch increases weakly with increasing the alkyl tail.

  12. Unequal Activities of Enantiomers via Biological Receptors: Examples of Chiral Drug, Pesticide, and Fragrance Molecules

    Science.gov (United States)

    Mannschreck, Albrecht; Kiesswetter, Roland; von Angerer, Erwin

    2007-01-01

    A molecule coming from outside an organism can form a ligand-receptor complex. Upon its formation, a message is transmitted, for example, to certain cells. In this way, two enantiomers can emit messages that differ, either quantitatively or qualitatively. In the present article, these facts are taken as a common basis for the actions of chiral…

  13. Surface activity of Acinetobacter calcoaceticus sp. 2CA2

    Energy Technology Data Exchange (ETDEWEB)

    Neufeld, R.J.; Zajic, J.E.

    1984-01-01

    The hydrocarbon metabolizing Acinetobacter calcoaceticus sp. 2CA2 reduces the surface tension of the culture broth during growth on liquid hydrocarbons. This activity, which is not evident during growth on soluble substrates, is associated with the whole cells. Removing the cells from the culture broth increases the surface tension of the liquid phase. The cells when resuspended in water result in a dramatic lowering of the surface tension. Acinetobacter sp. 2CA2 tends to partition between the two liquid phases during growth on hydrocarbons. Both the hydrocarbon bound and nonadhering cells are equally surface active. The whole cells are also able to form and stabilize kerosene-water emulsions. This ability is not related to the lowering of the liquid surface or interfacial tension, since both surface active and nonsurface active cells demonstrated the same emulsifying properties. An extracellular lipopeptide produced during growth on hydrocarbons is not surface active but effectively forms and stabilizes kerosene-water emulsions. The cells and extracellular lipopeptide are also effective in de-emulsifying surfactant stabilized test emulsions. The cells and extracellular lipopeptide are also effective in de-emulsifying surfactant stabilized test emulsions. The lipopeptide product reduced the half-life of a Tween-Span (TS) stabilized kerosene-water emulsion from 650 to 0.4 h at product concentrations of less than 1% (w/v).

  14. Cell-contact-dependent activation of CD4+T cells by adhesion molecules on synovial fibroblasts.

    Science.gov (United States)

    Mori, Masato; Hashimoto, Motomu; Matsuo, Takashi; Fujii, Takao; Furu, Moritoshi; Ito, Hiromu; Yoshitomi, Hiroyuki; Hirose, Jun; Ito, Yoshinaga; Akizuki, Shuji; Nakashima, Ran; Imura, Yoshitaka; Yukawa, Naoichiro; Yoshifuji, Hajime; Ohmura, Koichiro; Mimori, Tsuneyo

    2017-05-01

    To determine how cell-cell contact with synovial fibroblasts (SF) influence on the proliferation and cytokine production of CD4 +  T cells. Naïve CD4 +  T cells were cultured with SF from rheumatoid arthritis patients, stimulated by anti-CD3/28 antibody, and CD4 +  T cell proliferation and IFN-γ/IL-17 production were analyzed. To study the role of adhesion molecules, cell contact was blocked by transwell plate or anti-intracellular adhesion molecule-1 (ICAM-1)/vascular cell adhesion molecule-1(VCAM-1) antibody. To study the direct role of adhesion molecules for CD4 +  T cells, CD161 +  or CD161 - naïve CD4 +  T cells were stimulated on plastic plates coated by recombinant ICAM-1 or VCAM-1, and the source of IFN-γ/IL-17 were analyzed. SF enhanced naïve CD4 +  T cell proliferation and IFN-γ/IL-17 production in cell-contact and in part ICAM-1-/VCAM-1-dependent manner. Plate-coated ICAM-1 and VCAM-1 enhanced naïve CD4 +  T cell proliferation and IFN-γ production, while VCAM-1 efficiently promoting IL-17 production. CD161 +  naïve T cells upregulating LFA-1 and VLA-4 were the major source of IFN-γ/IL-17 upon interaction with ICAM-1/VCAM-1. CD4 +  T cells rapidly expand and secrete IFN-γ/IL-17 upon cell-contact with SF via adhesion molecules. Interfering with ICAM-1-/VCAM-1 may be beneficial for inhibiting RA synovitis.

  15. Experimental and QSAR study on the surface activities of alkyl imidazoline surfactants

    Science.gov (United States)

    Kong, Xiangjun; Qian, Chengduo; Fan, Weiyu; Liang, Zupei

    2018-03-01

    15 alkyl imidazoline surfactants with different structures were synthesized and their critical micelle concentration (CMC) and surface tension under the CMC (σcmc) in aqueous solution were measured at 298 K. 54 kinds of molecular structure descriptors were selected as independent variables and the quantitative structure-activity relationship (QSAR) between surface activities of alkyl imidazoline and molecular structure were built through the genetic function approximation (GFA) method. Experimental results showed that the maximum surface excess of alkyl imidazoline molecules at the gas-liquid interface increased and the area occupied by each surfactant molecule and the free energies of micellization ΔGm decreased with increasing carbon number (NC) of the hydrophobic chain or decreasing hydrophilicity of counterions, which resulted in a CMC and σcmc decrease, while the log CMC and NC had a linear relationship and a negative correlation. The GFA-QSAR model, which was generated by a training set composed of 13 kinds of alkyl imidazoline though GFA method regression analysis, was highly correlated with predicted values and experimental values of the CMC. The correlation coefficient R was 0.9991, which means high prediction accuracy. The prediction error of 2 kinds of alkyl imidazoline CMCs in the Validation Set that quantitatively analyzed the influence of the alkyl imidazoline molecular structure on the CMC was less than 4%.

  16. Transmembrane α-Helix 2 and 7 Are Important for Small Molecule-Mediated Activation of the GLP-1 Receptor

    DEFF Research Database (Denmark)

    Underwood, Christina Rye; Møller Knudsen, Sanne; Schjellerup Wulff, Birgitte

    2011-01-01

    Glucagon-like peptide-1 (GLP-1) activates the GLP-1 receptor (GLP-1R), which belongs to family B of the G-protein-coupled receptors. We previously identified a selective small molecule ligand, compound 2, that acted as a full agonist and allosteric modulator of GLP-1R. In this study......, the structurally related small molecule, compound 3, stimulated cAMP production from GLP-1R, but not from the homologous glucagon receptor (GluR). The receptor selectivity encouraged a chimeric receptor approach to identify domains important for compound 3-mediated activation of GLP-1R. A subsegment of the GLP-1R...... transmembrane domain containing TM2 to TM5 was sufficient to transfer compound 3 responsiveness to GluR. Therefore, divergent residues in this subsegment of GLP-1R and GluR are responsible for the receptor selectivity of compound 3. Functional analyses of other chimeric receptors suggested that the existence...

  17. Laser activation of diamond surface for electroless metal plating

    Science.gov (United States)

    Pimenov, S. M.; Shafeev, G. A.; Laptev, V. A.; Loubnin, E. N.

    1994-04-01

    Selective area electroless nickel and copper deposition onto the surface of diamond single crystals and polycrystalline diamond films has been realized. Three methods of laser-assisted activation of diamond surface were applied: (i) prenucleation of diamond surface with a thin layer of palladium catalyst via laser-induced decomposition of a palladium acetyl-acetonate [Pd(acac)2] solid film; (ii) deposition of palladium by means of the decomposition of Pd(acac)2 dissolved in dimethylformamide; (iii) laser-induced damage of diamond surface.

  18. The binding of monoclonal antibodies to cell surface molecules. Quantitative analysis of the reactions and cross-reactions of an antibody (MB40.3) with four HLA-B molecules.

    Science.gov (United States)

    Parham, P

    1984-11-10

    The MB40.3 monoclonal antibody binds to four distinct HLA-B molecules; B7, B40, B40*, and B27. With Fab' fragments only the interaction with B7 and B40 was detected and the affinity for both was the same (1-2 X 10(8) M-1) suggesting the epitope is shared by the two molecules. Unlike many antibodies for which low affinity is due to a high-dissociation constant, that of MB40.3 results from a very low-association rate constant, coupled with a low-dissociation constant. In consequence, the affinity and avidity of Fab', F(ab')2, and IgG for B7 and B40 were found to be of a similar magnitude, soluble B7 was a more efficient competitor for antibody than cell surface B7 and in practice antibody bivalency was of little importance. The forward rate constant could be increased by removing Fc from the antibody or by removing sialic acid from the cells by treatment with neuraminidase. The neuraminidase treatment also produced an increase in the number of detectable cell surface HLA-A,B molecules. The affinity of MB40.3 for B40* and B27 was estimated to be less than 4 X 10(6) as no binding with Fab' was detected due to a high-dissociation rate. For these two HLA-B molecules bivalent attachment was critical, and it increased the strength of interaction with cell surface B40* and B27 to a point where the avidities were comparable to those obtained with B7 and B40, with B40* interacting more strongly than B27. The epitopes recognized by MB40.3 on B40* and B27 were thus shown to be structurally different from each other and from those on B7 and B40. The properties of this antibody contrast with those of other anti-HLA-A,B we have studied (Ways, J.P., and Parham, P. (1983) Biochem. J. 216, 423-432).

  19. Directed assembly of optoelectronically active alkyl-π-conjugated molecules by adding n-alkanes or π-conjugated species

    Science.gov (United States)

    Hollamby, Martin J.; Karny, Maciej; Bomans, Paul H. H.; Sommerdjik, Nico A. J. M.; Saeki, Akinori; Seki, Shu; Minamikawa, Hiroyuki; Grillo, Isabelle; Pauw, Brian R.; Brown, Paul; Eastoe, Julian; Möhwald, Helmuth; Nakanishi, Takashi

    2014-08-01

    Supramolecular assembly can yield ordered structures by taking advantage of the cumulative effect of multiple non-covalent interactions between adjacent molecules. The thermodynamic origin of many self-assembled structures in water is the balance between the hydrophilic and hydrophobic segments of the molecule. Here, we show that this approach can be generalized to use solvophobic and solvophilic segments of fully hydrophobic alkylated fullerene molecules. Addition of n-alkanes results in their assembly—due to the antipathy of C60 towards n-alkanes—into micelles and hexagonally packed gel-fibres containing insulated C60 nanowires. The addition of pristine C60 instead directs the assembly into lamellar mesophases by increasing the proportion of π-conjugated material in the mixture. The assembled structures contain a large fraction of optoelectronically active material and exhibit comparably high photoconductivities. This method is shown to be applicable to several alkyl-π-conjugated molecules, and can be used to construct organized functional materials with π-conjugated sections.

  20. Structures of Clostridium Botulinum Neurotoxin Serotype A Light Chain Complexed with Small-Molecule Inhibitors Highlight Active-Site Flexibility

    Energy Technology Data Exchange (ETDEWEB)

    Silvaggi,N.; Boldt, G.; Hixon, M.; Kennedy, J.; Tzipori, S.; Janda, K.; Allen, K.

    2007-01-01

    The potential for the use of Clostridial neurotoxins as bioweapons makes the development of small-molecule inhibitors of these deadly toxins a top priority. Recently, screening of a random hydroxamate library identified a small-molecule inhibitor of C. botulinum Neurotoxin Serotype A Light Chain (BoNT/A-LC), 4-chlorocinnamic hydroxamate, a derivative of which has been shown to have in vivo efficacy in mice and no toxicity. We describe the X-ray crystal structures of BoNT/A-LC in complexes with two potent small-molecule inhibitors. The structures of the enzyme with 4-chlorocinnamic hydroxamate or 2,4-dichlorocinnamic hydroxamate bound are compared to the structure of the enzyme complexed with L-arginine hydroxamate, an inhibitor with modest affinity. Taken together, this suite of structures provides surprising insights into the BoNT/A-LC active site, including unexpected conformational flexibility at the S1' site that changes the electrostatic environment of the binding pocket. Information gained from these structures will inform the design and optimization of more effective small-molecule inhibitors of BoNT/A-LC.

  1. Coamorphous Active Pharmaceutical Ingredient-Small Molecule Mixtures: Considerations in the Choice of Coformers for Enhancing Dissolution and Oral Bioavailability.

    Science.gov (United States)

    Newman, Ann; Reutzel-Edens, Susan M; Zografi, George

    2018-01-01

    In the recent years, coamorphous systems, containing an active pharmaceutical ingredient (API) and a small molecule coformer have appeared as alternatives to the use of either amorphous solid dispersions containing polymer or cocrystals of API and small molecule coformers, to improve the dissolution and oral bioavailability of poorly soluble crystalline API. This Commentary article considers the relative properties of amorphous solid dispersions and coamorphous systems in terms of methods of preparation; miscibility; glass transition temperature; physical stability; hygroscopicity; and aqueous dissolution. It also considers important questions concerning the fundamental criteria to be used for the proper selection of a small molecule coformer regarding its ability to form either coamorphous or cocrystal systems. Finally, we consider various aspects of product development that are specifically associated with the formulation of commercial coamorphous systems as solid oral dosage forms. These include coformer selection; screening; methods of preparation; preformulation; physical stability; bioavailability; and final formulation. Through such an analysis of coamorphous API-small molecule coformer systems, against the more widely studied API-polymer dispersions and cocrystals, it is believed that the strengths and weaknesses of coamorphous systems can be better understood, leading to more efficient formulation and manufacture of such systems for enhancing oral bioavailability. Copyright © 2018 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

  2. Single molecule measurements of DNA helicase activity with magnetic tweezers and t-test based step-finding analysis

    Science.gov (United States)

    Seol, Yeonee; Strub, Marie-Paule; Neuman, Keir C.

    2016-01-01

    Magnetic tweezers is a versatile and easy to implement single-molecule technique that has become increasingly prevalent in the study of nucleic acid based molecular motors. Here, we provide a description of the magnetic tweezers instrument and guidelines for measuring and analyzing DNA helicase activity. Along with experimental methods, we describe a robust method of single-molecule trajectory analysis based on the Student’s t-test that accommodates continuous transitions in addition to the discrete transitions assumed in most widely employed analysis routines. To illustrate the single-molecule unwinding assay and the analysis routine, we provide DNA unwinding measurements of Escherichia coli RecQ helicase under a variety of conditions (Na+, ATP, temperature, and DNA substrate geometry). These examples reveal that DNA unwinding measurements under various conditions can aid in elucidating the unwinding mechanism of DNA helicase but also emphasize that environmental effects on DNA helicase activity must be considered in relation to in vivo activity and mechanism. PMID:27131595

  3. Activation of CO2 and Related Small Molecules by Neopentyl-Derivatized Uranium Complexes

    OpenAIRE

    Schmidt, Anna-Corina

    2015-01-01

    The world´s concern about the environment has continued to intensify as the effects of greenhouse gases or complicated work-up and disposal of radioactive substances become more obvious and profound. Unsurprisingly, the number of publications related to the solution of these issues has greatly increased in the last 15 years. Thus, a basic understanding of the specific properties and behavior of small molecules is crucial for the reduction of greenhouse gases, which may be realized through act...

  4. Quantum chemical investigation of the interaction between a hydrogen molecule and a solid surface using the partitioning technique

    International Nuclear Information System (INIS)

    Kuenne, L.D.

    1984-01-01

    The partitioning technique is used to investigate the chemisorption of hydrogen. Including non-zero overlap between atomic orbitals the developed formulation of the problem is valid in any LCAO-approximation. Its extension to the problem of chemisorption of other molecules is briefly discussed. (author)

  5. Allelic imbalance modulates surface expression of the tolerance-inducing HLA-G molecule on primary trophoblast cells

    DEFF Research Database (Denmark)

    Djurisic, S; Teiblum, S; Tolstrup, C K

    2015-01-01

    The HLA-G molecule is expressed on trophoblast cells at the feto-maternal interface, where it interacts with local immune cells, and upholds tolerance against the semi-allogeneic fetus. Aberrant HLA-G expression in the placenta and reduced soluble HLA-G levels are observed in pregnancy complicati...

  6. Surface tension prevails over solute effect in organic-influenced cloud droplet activation

    Science.gov (United States)

    Ovadnevaite, Jurgita; Zuend, Andreas; Laaksonen, Ari; Sanchez, Kevin J.; Roberts, Greg; Ceburnis, Darius; Decesari, Stefano; Rinaldi, Matteo; Hodas, Natasha; Facchini, Maria Cristina; Seinfeld, John H.; O' Dowd, Colin

    2017-06-01

    The spontaneous growth of cloud condensation nuclei (CCN) into cloud droplets under supersaturated water vapour conditions is described by classic Köhler theory. This spontaneous activation of CCN depends on the interplay between the Raoult effect, whereby activation potential increases with decreasing water activity or increasing solute concentration, and the Kelvin effect, whereby activation potential decreases with decreasing droplet size or increases with decreasing surface tension, which is sensitive to surfactants. Surface tension lowering caused by organic surfactants, which diminishes the Kelvin effect, is expected to be negated by a concomitant reduction in the Raoult effect, driven by the displacement of surfactant molecules from the droplet bulk to the droplet-vapour interface. Here we present observational and theoretical evidence illustrating that, in ambient air, surface tension lowering can prevail over the reduction in the Raoult effect, leading to substantial increases in cloud droplet concentrations. We suggest that consideration of liquid-liquid phase separation, leading to complete or partial engulfing of a hygroscopic particle core by a hydrophobic organic-rich phase, can explain the lack of concomitant reduction of the Raoult effect, while maintaining substantial lowering of surface tension, even for partial surface coverage. Apart from the importance of particle size and composition in droplet activation, we show by observation and modelling that incorporation of phase-separation effects into activation thermodynamics can lead to a CCN number concentration that is up to ten times what is predicted by climate models, changing the properties of clouds. An adequate representation of the CCN activation process is essential to the prediction of clouds in climate models, and given the effect of clouds on the Earth’s energy balance, improved prediction of aerosol-cloud-climate interactions is likely to result in improved assessments of future

  7. Surface tension prevails over solute effect in organic-influenced cloud droplet activation.

    Science.gov (United States)

    Ovadnevaite, Jurgita; Zuend, Andreas; Laaksonen, Ari; Sanchez, Kevin J; Roberts, Greg; Ceburnis, Darius; Decesari, Stefano; Rinaldi, Matteo; Hodas, Natasha; Facchini, Maria Cristina; Seinfeld, John H; O' Dowd, Colin

    2017-06-29

    The spontaneous growth of cloud condensation nuclei (CCN) into cloud droplets under supersaturated water vapour conditions is described by classic Köhler theory. This spontaneous activation of CCN depends on the interplay between the Raoult effect, whereby activation potential increases with decreasing water activity or increasing solute concentration, and the Kelvin effect, whereby activation potential decreases with decreasing droplet size or increases with decreasing surface tension, which is sensitive to surfactants. Surface tension lowering caused by organic surfactants, which diminishes the Kelvin effect, is expected to be negated by a concomitant reduction in the Raoult effect, driven by the displacement of surfactant molecules from the droplet bulk to the droplet-vapour interface. Here we present observational and theoretical evidence illustrating that, in ambient air, surface tension lowering can prevail over the reduction in the Raoult effect, leading to substantial increases in cloud droplet concentrations. We suggest that consideration of liquid-liquid phase separation, leading to complete or partial engulfing of a hygroscopic particle core by a hydrophobic organic-rich phase, can explain the lack of concomitant reduction of the Raoult effect, while maintaining substantial lowering of surface tension, even for partial surface coverage. Apart from the importance of particle size and composition in droplet activation, we show by observation and modelling that incorporation of phase-separation effects into activation thermodynamics can lead to a CCN number concentration that is up to ten times what is predicted by climate models, changing the properties of clouds. An adequate representation of the CCN activation process is essential to the prediction of clouds in climate models, and given the effect of clouds on the Earth's energy balance, improved prediction of aerosol-cloud-climate interactions is likely to result in improved assessments of future

  8. Surface-activated joining method for surveillance coupon reconstitution

    International Nuclear Information System (INIS)

    Kaihara, Shoichiro; Nakamura, Terumi

    1993-01-01

    As nuclear power plants approach the end of their license periods and license renewal is contemplated, there is an increasing need to expand the data base of mechanical properties obtainable from archival surveillance specimens. A new joining method for reconstituting broken Charpy specimens is being developed, the objective being to retain the original properties of the material in the process. The new method is called surface-activated joining (SAJ). It is designed to obtain a good junction without applying extra heating and deformation. In particular, the purpose of SAJ is to minimize the width of the heat-affected zone (HAZ) and to decrease the maximum temperature experienced by the specimen during reconsolidation of the two pieces. Generally, machined metal surfaces are contaminated with films of oxide, adsorbed gas, oil, or other vapors that impede bonding of surfaces during joining. However, if surface contamination is removed and the two surfaces are mated as closely as possible, joining can be achieved at low temperatures and modest stress levels. In order to apply the SAJ method, the following requirements must be met: (1) inert atmosphere to protect the surfaces from atmospheric gases and oxidation; (2) removal of the existing contamination layers to activate the surfaces; and (3) method for bringing the two surfaces into very intimate contact prior to joining

  9. Surface activity, lipid profiles and their implications in cervical cancer.

    Directory of Open Access Journals (Sweden)

    Preetha A

    2005-01-01

    Full Text Available Background: The profiles of lipids in normal and cancerous tissues may differ revealing information about cancer development and progression. Lipids being surface active, changes in lipid profiles can manifest as altered surface activity profiles. Langmuir monolayers offer a convenient model for evaluating surface activity of biological membranes. Aims: The aims of this study were to quantify phospholipids and their effects on surface activity of normal and cancerous human cervical tissues as well as to evaluate the role of phosphatidylcholine (PC and sphingomyelin (SM in cervical cancer using Langmuir monolayers. Methods and Materials: Lipid quantification was done using thin layer chromatography and phosphorus assay. Surface activity was evaluated using Langmuir monolayers. Monolayers were formed on the surface of deionized water by spreading tissue organic phase corresponding to 1 mg of tissue and studying their surface pressure-area isotherms at body temperature. The PC and SM contents of cancerous human cervical tissues were higher than those of the normal human cervical tissues. Role of PC and SM were evaluated by adding varying amounts of these lipids to normal cervical pooled organic phase. Statistical analysis: Student′s t-test (p < 0.05 and one-way analysis of variance (ANOVA was used. Results: Our results reveals that the phosphatidylglycerol level in cancerous cervical tissue was nearly five folds higher than that in normal cervical tissue. Also PC and sphingomyelin SM were found to be the major phospholipid components in cancerous and normal cervical tissues respectively. The addition of either 1.5 µg DPPC or 0.5 µg SM /mg of tissue to the normal organic phase changed its surface activity profile to that of the cancerous tissues. Statistically significant surface activity parameters showed that PC and SM have remarkable roles in shifting the normal cervical lipophilic surface activity towards that of cancerous lipophilic

  10. HLA-F is a surface marker on activated lymphocytes.

    Science.gov (United States)

    Lee, Ni; Ishitani, Akiko; Geraghty, Daniel E

    2010-08-01

    Of the three nonclassical class I antigens expressed in humans, HLA-F has been least characterized with regard to expression or function. In this study, we examined HLA-F expression focusing on lymphoid cells, where our previous work with homologous cell lines had demonstrated surface HLA-F expression. HLA-F protein expression was observed by Western blot analysis in all resting lymphocytes, including B cells, T cells, NK cells, and monocytes, all of which lacked surface expression in the resting state. Upon activation, using a variety of methods to activate different lymphocyte subpopulations, all cell types that expressed HLA-F intracellularly showed an induction of surface HLA-F protein. An examination of peripheral blood from individuals genetically deficient for TAP and tapasin expression demonstrated the same activation expression profiles for HLA-F,but with altered kinetics post-activation. Further analysis of CD41+CD25+1 Treg showed that HLA-F was not upregulated on the major fraction of these cells when they were activated,whereas CD41+CD25- T cells showed strong expression of surface HLA-F when activated under identical conditions. These findings are discussed with regard to possible functions for HLA-F and its potential clinical use as a marker of an activated immune response.

  11. Synthesis and surface active properties of cationic surface active agents from crude rice bran oil

    Directory of Open Access Journals (Sweden)

    El-Dougdoug, W. I. A.

    1999-10-01

    Full Text Available Cationic surfactants of 2-hidroxy-3-(2- alkylamidopolyethyl amino propane-1-triethylammonium hydroxides (ix-xuia-d were prepared from fatty acids (ia-d [palmitic, stearic, oleic, linoleic acid] and mixed fatty acids of crude rice bran oil ie [RBO]. The reaction of these acids with ethylenediamine, diethylenetriamine, triethylenetetramine andletraethylenepentamine (iia-d produced (iii-viia-d. The produced amidopolyethylamine (iii-viia-d reacted with 2-epoxypropylenetriethylammonium chloride (viii to give the cationic surfactants (ix-xiiia-d . The produced derivatives were purified and characterized by microanalysis, molecular weight determination, infra-red (IR, and proton nuclear magnetic resonance (1H NMR spectra. The surface active properties and inhibition efficiency of the prepared cationic surfactants were determined.

    Se han preparado tensioactivos catiónicos de hidróxidos de! 2-hidroxi-3-(2-alquilamidopolietilamino propano-1;trietilamonio (ix-xiiia-d a partir de los ácidos grasos (ia-d [ácido palmítico, esteárico, oleico y linoleico] y mezclas de ácidos grasos de aceite de germen de arroz crudo ie [RBO]. La reacción de estos ácidos con etilenodiamina, dietilenotriamina, trietilenotetramina y tetraetilenopentamina (iia-d produjo los compuestos (iv-viia-d . Los amidopolietilaminos producidos (iii-viia-d reaccionaron con el cloruro de 2-epoxipropilenotrietilamonio (viii para dar los tensioactivos catiónicos (ix-xiiia-d. Los derivados producidos se purificaron y caracterizaron por microanálisis, determinación del peso molecular, espectros de infrarrojo (IR y resonancia magnética nuclear de protón (1H NMR. Se determinaron las propiedades tensioactivas y la eficacia de inhibición de los tensioactivos cati

  12. Staphylococcus-mediated T-cell activation and spontaneous natural killer cell activity in the absence of major histocompatibility complex class II molecules

    Science.gov (United States)

    Chapes, S. K.; Hoynowski, S. M.; Woods, K. M.; Armstrong, J. W.; Beharka, A. A.; Iandolo, J. J.; Spooner, B. S. (Principal Investigator)

    1993-01-01

    We used major histocompatibility complex class II antigen-deficient transgenic mice to show that in vitro natural killer cell cytotoxicity and T-cell activation by staphylococcal exotoxins (superantigens) are not dependent upon the presence of major histocompatibility complex class II molecules. T cells can be activated by exotoxins in the presence of exogenously added interleukin 1 or 2 or in the presence of specific antibody without exogenously added cytokines.

  13. Mechanochemical activation and gallium and indiaarsenides surface catalycity

    Science.gov (United States)

    Kirovskaya, I. A.; Mironova, E. V.; Umansky, I. V.; Brueva, O. Yu; Murashova, A. O.; Yureva, A. V.

    2018-01-01

    The present work has been carried out in terms of determining the possibilities for a clearer identification of the active sites nature, intermediate surface compounds nature, functional groups during adsorption and catalysis, activation of the diamond-like semiconductors surface (in particular, the AIIIBV type) based on mechanochemical studies of the “reaction medium (H2O, iso-C3H7OH) - dispersible semiconductor (GaAs, InAs)” systems. As a result, according to the read kinetic curves of dispersion in water, both acidification and alkalinization of the medium have been established and explained; increased activity of the newly formed surface has been noted; intermediate surface compounds, functional groups appearing on the real surface and under H2O adsorption conditions, adsorption and catalytic decomposition of iso-C3H7OH have been found (with explanation of the origin). The unconcealed role of coordinatively unsaturated atoms as active sites of these processes has been shown; the relative catalytic activity of the semiconductors studied has been evaluated. Practical recommendations on the preferred use of gallium arsenide in semiconductor gas analysis and semiconductor catalysis have been given in literature searches, great care should be taken in constructing both.

  14. Siloxides as supporting ligands in uranium(III)-mediated small-molecule activation

    Energy Technology Data Exchange (ETDEWEB)

    Mougel, Victor; Camp, Clement; Pecaut, Jacques; Mazzanti, Marinella [Laboratoire de Reconnaissance Ionique et Chimie de Coordination, SCIB, UMR-E3 CEA-UJF, INAC, CEA-Grenoble (France); Coperet, Christophe [Laboratory of Inorganic Chemistry, ETH Zurich (Switzerland); Maron, Laurent; Kefalidis, Christos E. [LPCNO, CNRS and INSA, UPS, Universite de Toulouse (France)

    2012-12-03

    Siloxides can support U..in the reduction of small molecules with uranium complexes. The treatment of [U{N(SiMe_3)_2}{sub 3}] with HOSi(OtBu){sub 3} (3 equiv) yielded a novel homoleptic uranium(III) siloxide complex 1, which acted as a two-electron reducing agent toward CS{sub 2} and CO{sub 2}. Complex 1 also reduced toluene to afford a diuranium inverted-sandwich complex. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  15. In silico Screening and Evaluation of the Anticonvulsant Activity of Docosahexaenoic Acid-Like Molecules in Experimental Models of Seizures.

    Science.gov (United States)

    Gharibi Loron, Ali; Sardari, Soroush; Narenjkar, Jamshid; Sayyah, Mohammad

    2017-01-01

    Resistance to antiepileptic drugs and the intolerability in 20-30% of the patients raises demand for developing new drugs with improved efficacy and safety. Acceptable anticonvulsant activity, good tolerability, and inexpensiveness of docosahexaenoic acid (DHA) make it as a good candidate for designing and development of the new anticonvulsant medications. Ten DHA-based molecules were screened based on in silico screening of DHA-like molecules by root-mean-square deviation of atomic positions, the biological activity score of Professional Association for SQL Server, and structural requirements suggested by pharmacophore design. Anticonvulsant activity was tested against clonic seizures induced by pentylenetetrazole (PTZ, 60 mg/kg, i.p.) and tonic seizures induced by maximal electroshock (MES, 50 mA, 50 Hz, 1 ms duration) by intracerebroventricular (i.c.v.) injection of the screened compounds to mice. Among screened compounds, 4-Phenylbutyric acid, 4-Biphenylacetic acid, phenylacetic acid, and 2-Phenylbutyric acid showed significant protective activity in pentylenetetrazole test with ED50 values of 4, 5, 78, and 70 mM, respectively. In MES test, shikimic acid and 4-tert-Butylcyclo-hexanecarboxylic acid showed significant activity with ED50 values 29 and 637 mM, respectively. Effective compounds had no mortality in mice up to the maximum i.c.v. injectable dose of 1 mM. Common electrochemical features and three-dimensional spatial structures of the effective compounds suggest the involvement of the anticonvulsant mechanisms similar to the parent compound DHA.

  16. Atomic and molecular layer activation of dielectric surfaces

    Science.gov (United States)

    Senkevich, John Joseph

    Strong interaction between the material deposit and substrate is critical to stable deposits and interfaces. The work presented here focuses on the surface activation of dielectric surfaces and oxidized metal surfaces to promote the chemisorption of palladium (II) hexafluoroacetylacetonate (PdII (hfac)2). The goal is to develop reliable, robust metallization protocols, which enable strong interactions between the metal and substrate. SiO2, air exposed Ta, Trikon, and SiLK were activated with sulfur or phosphorus. Two types of activations were developed; one based on self-assembled chemistry, and the other a plasma-assisted process. Activation of the surface using self-assembly techniques was carried out using mercaptan-terminated silane and tetrasulfide silane. The resulting films were characterized by variable angle spectroscopic ellipsometry, contact angle goniometry, and X-ray photoelectron spectroscopy. Tetrasulfide silane sources films exhibit self-limiting behavior, even in the presence of water vapor; whereas mercaptan-terminated silane sourced films tend to be thicker. The surface activations using atomic layers of sulfur and phosphorus were carried out in a rf plasma chamber using hydrogen sulfide and phosphine sources, respectively. The activations were studied as functions of rf power, system pressure, and substrate material. Results show that higher rf powers and lower system pressures promote greater surface coverages by sulfur with a reduced oxidation state. The activated dielectrics show evidence of PdII(hfac)2 chemisorption, in contrast to non-activated surfaces. The binding energy shift of the Pd3d 5/2 XPS peak towards elemental Pd provides evidence for the dissociative chemisorption of PdII(hfac)2. The extent of dissociation depends on the substrate temperature and the activation method used. The conclusions of the work presented here have implications for metallization using highly polarizable transition metals. Specifically, it can be applied to

  17. Surprising phenomena at the surface of solids: complex molecule emission after impact of ions or of energetic photons

    International Nuclear Information System (INIS)

    Le Beyec, Y.

    1990-01-01

    The vanishing of large mass molecules, by particle or photon impact is an unexpected behavior of the matter which allows to study the medium answer to the interaction. This phenomenon has several applications and gives rise development of analysis scientific instrumentation for non volatile compounds as the time of flight mass spectrometers. - In this report, the point is made about the induced desorption by rapid heavy ions [fr

  18. Functioned silver nanoparticle loaded activated carbon for the recovery of bioactive molecule from bacterial fermenter for its bactericidal activity

    Science.gov (United States)

    Arivizhivendhan, Villalan; Mahesh, Mannacharaju; Boopathy, Ramasamy; Karthikeyan, Sekar; Mary, Rathanasamy Regina; Sekaran, Ganesan

    2018-01-01

    A novel continuous production and extraction of bacterial bioactive prodigiosin (PG) from fermented using silver nanoparticle impregnated functioned activated carbon composite is proposed for cost-effective and ecofriendly microbial technique. Hence, in this investigation silver nanoparticle was impregnated onto functioned activated carbon ([AC]F) as a support matrix and to enable the separation of PG conjugated silver nanoparticle from the fermented medium. A laboratory scale experiment was carried out to evaluate the continuous production and recovery of PG using [AC@Ag]F. Ag nanoparticle impregnated [AC]F ([AC@Ag]F) characterized by FT-IR, XRD, TGA, DSC and SEM. Instrumental analyses confirmed that Ag nanoparticles significantly impregnated on AC through the functionalization of AC with diethanolamine and it enhances the binding capacity between AC and Ag. The various process parameters, such as contact time, pH, and mass of [AC@Ag]F, were statistically optimized for the recovery of PG using Response Surface Methodology (RSM). The maximum extraction of PG in [AC@Ag]F was found to be 16.2 ± 0.2 mg g-1, its twofold higher than [AC]F. Further, PG conjugated [AC@Ag]F and ([AC@Ag]F-PG) were checked for the growth inhibition of gram negative and gram positive bacteria without formation of biofilm upto 96 h. Hence, the developed matrix could be eco-friendly, viable and lower energy consumption step for separation of the bacterial bioactive PG from fermented broth. In additionally, [AC@Ag]F-PG was used as an antifouling matrix without formation of biofilm.

  19. Charge-controlled fixation of DNA molecules on silicon surface and electro-physical properties of Au–DNA–Si interface

    Energy Technology Data Exchange (ETDEWEB)

    Bazlov, N.V., E-mail: nikolay.bazlov@gmail.com [V.A. Fok Institute of Physics, Saint-Petersburg State University, Ulyanovskaya 1, 198504 Saint-Petersburg (Russian Federation); Vyvenko, O.F.; Sokolov, P.A.; Kas’yanenko, N.A.; Petrov, Yu V. [V.A. Fok Institute of Physics, Saint-Petersburg State University, Ulyanovskaya 1, 198504 Saint-Petersburg (Russian Federation)

    2013-02-15

    Light-induced fixation of DNA molecules on silicon surface was done and electro-physical properties of Schottky diodes with DNA on interfaces were investigated. Thymus DNA molecules were deposited on silicon from a water solution. Fixed molecular structures were observed with helium ionic microscopy and atomic force microscopy and then they were covered with thermal sputtered gold film. Obtained structures Au–DNA–(n-Si) were examined with current–voltage and frequency dependent admittance measurements. In darkness immobilizing of molecules leaded to form DNA ropes with thickness up to 10 nm and distances between them about 1 mkm. Fixation under illumination resulted in forming of single DNA mesh with thickness about 1 nm and cell size about 100 nm. Presence of molecular mesh on interface leaded to increasing of charge density controlled by metal Fermi level and improved diode quality. Presence of molecular ropes resulted in increasing of charge density controlled by semiconductor. From the estimation of interface state density values the origin of the states at the interface between DNA and silicon substrate is suggested to be DNA phosphate groups contacting or being close to the substrate surface.

  20. High sensitivity surface plasmon resonance biosensor for detection of microRNA and small molecule based on graphene oxide-gold nanoparticles composites.

    Science.gov (United States)

    Li, Qing; Wang, Qing; Yang, Xiaohai; Wang, Kemin; Zhang, Hua; Nie, Wenyan

    2017-11-01

    A versatile and sensitive surface plasmon resonance (SPR) biosensor based on two layers of graphene oxide-gold nanoparticles (GO-AuNPs) composites was designed for the detection of microRNA (miRNA) and small molecule adenosine. The bottom layer, which acted as a functionalized substrate on the sensor chip, provided a high specific surface area convenient for the immobilization of capture DNA molecules. The upper layer served as a signal-amplification element. By employing these two layers of GO-AuNPs composites, the dual amplification strategy was achieved so that a measurement of miRNA-141 with a detection limit of 0.1fM was obtained. Moreover, the developed SPR biosensor showed decent selectivity toward miRNA-200 family members. Especially, the SPR biosensor demonstrated its applicability for the detection of miRNA-141 in cancer cell extractions, and the results obtained were consistent with those obtained by qRT-PCR. Interestingly, small molecule adenosine could also be detected using this SPR biosensor in combination with a split aptamer. Considering the superior sensitivity, selectivity and generality, this work promised much potential for the detection of various biomolecules. Copyright © 2017 Elsevier B.V. All rights reserved.

  1. Effects of Surface Treatment of Activated Carbon on Its Surface and Cr(VI) Adsorption Characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Park, Soo Jin; Jang, Yu Sin [Advanced Materials Division., Korea Research Institute of Chimical Technology, Taejon (Korea)

    2001-04-01

    In this work, the effect of surface treatments on activated carbons (ACs) has been studied in the context of gas and liquid adsorption behaviors. The chemical solutions used in this experiment were 35% sodium hydroxide, and these were used for the acidic and basic treatments, respectively. The surface properties have been determined by pH, acid-base values, and FT-IR. The adsorption isotherms of Cr(VI) ion on activated carbons have been studied with the 5 mg/l concentration at ambient temperature. N{sub 2} adsorption isotherm characteristics, which include the specific surface area, micro pore volume, and microporosity, were determined by BET and Boer's-plot methods. In case of the acidic treatment of activated carbons, it was observed that the adsorption of Cr(VI) ion was more effective due to the increase acid value (or acidic functional group) of activated carbon surfaces. However, the basic treatment on activated carbons was caused no significant effects, probably due to the decreased specific surface area and total pore volume. 27 refs., 7 figs., 4 tabs.

  2. Magnetic susceptibility of oxygen adsorbed on the surface of spherical and fibrous activated carbon.

    Directory of Open Access Journals (Sweden)

    Kiyoshi Kawamura

    2009-02-01

    Full Text Available The magnetic susceptibilities of oxygen adsorbed on the surface of bead-shaped activated carbon and activated carbon fibers were evaluated as a function of temperature between 4.2 K and 300 K, and found to exhibit a sharp peak at around 50 K. This implies that the adsorbed oxygen molecules form an antiferromagnetic state. The relation between the susceptibility and the adsorbed mass suggest that the thickness of the adsorbed oxygen is thin enough to consider a two-dimensional structure for bead–shaped activated carbon and carbon fibers across the fiber axis but thick enough to regard it as three-dimensional along the fiber axis. The result is discussed with reference to the study on one-dimensional oxygen array.

  3. Response surface optimisation for activation of bentonite with microwave irradiation

    Directory of Open Access Journals (Sweden)

    Rožić Ljiljana S.

    2011-01-01

    Full Text Available In this study, the statistical design of the experimental method was applied on the acid activation process of bentonite with microwave irradiation. The influence of activation parameters (time, acid normality and microwave heating power on the selected process response of the activated bentonite samples was studied. The specific surface area was chosen for the process response, because the chemical, surface and structural properties of the activated clay determine and limit its potential applications. The relationship of various process parameters with the specific surface area of bentonite was examined. A mathematical model was developed using a second-order response surface model (RSM with a central composite design incorporating the above mentioned process parameters. The mathematical model developed helped in predicting the variation in specific surface area of activated bentonite with time (5-21 min, acid normality (2-7 N and microwave heating power (63-172 W. The calculated regression models were found to be statistically significant at the required range and presented little variability. Furthermore, high values of R2 (0.957 and R2 (adjusted (0.914 indicate a high dependence and correlation between the observed and the predicted values of the response. These high values also indicate that about 96% of the result of the total variation can be explained by this model. In addition, the model shows that increasing the time and acid normality improves the textural properties of bentonites, resulting in increased specific surface area. This model also can be useful for setting an optimum value of the activation parameters for achieving the maximum specific surface area. An optimum specific surface area of 142 m2g-1 was achieved with an acid normality of 5.2 N, activation time of 7.38 min and microwave power of 117 W. Acid activation of bentonite was found to occur faster with microwave irradiation than with conventional heating. Microwave

  4. Linear response theory of activated surface diffusion with interacting adsorbates

    Energy Technology Data Exchange (ETDEWEB)

    Marti' nez-Casado, R. [Department of Chemistry, Imperial College London, South Kensington, London SW7 2AZ (United Kingdom); Sanz, A.S.; Vega, J.L. [Instituto de Fi' sica Fundamental, Consejo Superior de Investigaciones Cientificas, Serrano 123, 28006 Madrid (Spain); Rojas-Lorenzo, G. [Instituto Superior de Tecnologi' as y Ciencias Aplicadas, Ave. Salvador Allende, esq. Luaces, 10400 La Habana (Cuba); Instituto de Fi' sica Fundamental, Consejo Superior de Investigaciones Cienti' ficas, Serrano 123, 28006 Madrid (Spain); Miret-Artes, S., E-mail: s.miret@imaff.cfmac.csic.es [Instituto de Fi' sica Fundamental, Consejo Superior de Investigaciones Cienti' ficas, Serrano 123, 28006 Madrid (Spain)

    2010-05-12

    Graphical abstract: Activated surface diffusion with interacting adsorbates is analyzed within the Linear Response Theory framework. The so-called interacting single adsorbate model is justified by means of a two-bath model, where one harmonic bath takes into account the interaction with the surface phonons, while the other one describes the surface coverage, this leading to defining a collisional friction. Here, the corresponding theory is applied to simple systems, such as diffusion on flat surfaces and the frustrated translational motion in a harmonic potential. Classical and quantum closed formulas are obtained. Furthermore, a more realistic problem, such as atomic Na diffusion on the corrugated Cu(0 0 1) surface, is presented and discussed within the classical context as well as within the framework of Kramer's theory. Quantum corrections to the classical results are also analyzed and discussed. - Abstract: Activated surface diffusion with interacting adsorbates is analyzed within the Linear Response Theory framework. The so-called interacting single adsorbate model is justified by means of a two-bath model, where one harmonic bath takes into account the interaction with the surface phonons, while the other one describes the surface coverage, this leading to defining a collisional friction. Here, the corresponding theory is applied to simple systems, such as diffusion on flat surfaces and the frustrated translational motion in a harmonic potential. Classical and quantum closed formulas are obtained. Furthermore, a more realistic problem, such as atomic Na diffusion on the corrugated Cu(0 0 1) surface, is presented and discussed within the classical context as well as within the framework of Kramer's theory. Quantum corrections to the classical results are also analyzed and discussed.

  5. Low Energy Surface Activation of Zirconia Based Restorations.

    Science.gov (United States)

    Aboushelib, Moustafa N

    2016-03-01

    To evaluate the influence of low energy surface activation technique on the biaxial flexure strength of zirconia frameworks. Zirconia discs were prepared by cutting CAD/CAM zirconia blocks. Sintered discs were airborne particle abraded using one of the following particles: 30 μm alumina particles, 50 μm alumina particles, or modified round edges 30 μm alumina particles at low pressure. Scanning electron microscopy, x-ray diffraction analysis, surface roughness, and biaxial flexure strength tests were performed (n = 20). Fractured specimens were fractographically analyzed (α = 0.05). Low energy surface activation resulted in 7% monoclinic crystallographic transformation, increasing surface roughness from 0.05 to 0.3 μm and in significant increase in biaxial flexure strength (1718 MPa) compared 30 μm (1064 MPa), 50 μm (1210 MPa), and as-sintered specimens (1150 MPa). Low energy surface activation of zirconia specimens improved the biaxial flexure strength of zirconia frameworks without creation of surface damage. Clinical implications: by controlling particle size and shape of alumina, the flexure strength of zirconia restorations could be increased usinglow pressure particle abrasion.

  6. Particle surface area and bacterial activity in recirculating aquaculture systems

    DEFF Research Database (Denmark)

    Pedersen, Per Bovbjerg; von Ahnen, Mathis; Fernandes, Paulo

    2017-01-01

    Suspended particles in recirculating aquaculture systems (RAS) provide surface area that can be colonized by bacteria. More particles accumulate as the intensity of recirculation increases thus potentially increasing the bacterial carrying capacity of the systems. Applying a recent, rapid, cultur...... for determining bacterial activity might provide a means for future monitoring and assessment of microbial water quality in aquaculture farming systems......Suspended particles in recirculating aquaculture systems (RAS) provide surface area that can be colonized by bacteria. More particles accumulate as the intensity of recirculation increases thus potentially increasing the bacterial carrying capacity of the systems. Applying a recent, rapid, culture......-independent fluorometric detection method (Bactiquant®) for measuring bacterial activity, the current study explored the relationship between total particle surface area (TSA, derived from the size distribution of particles >5 μm) and bacterial activity in freshwater RAS operated at increasing intensity of recirculation...

  7. Active surface system for the new Sardinia Radiotelescope

    Science.gov (United States)

    Orfei, Alessandro; Morsiani, Marco; Zacchiroli, Giampaolo; Maccaferri, Giuseppe; Roda, Juri; Fiocchi, Franco

    2004-09-01

    In this paper we'll describe the active surface system that will be provided on the new Italian radiotelescope being in the phase of erection in the Sardinia Island. SRT (Sardinia Radiotelescope) will be a 64m shaped dish working up to 100GHz by exploiting the active surface facility designed by the authors. This facility will overcome the effects of gravity deformations on the antenna gain and will also be used to re-shape in a parabolic form the primary mirror, in order to avoid large phase error contribution on the antenna gain for the highest frequencies placed on the primary focus. Together with the description of the SRT system, a wide overview will be given regarding our previous installation of an active surface system, that can be seen like a prototype for SRT, mounted on the 32m dish of the Noto antenna.

  8. Electronic energy transfer from molecules to metal and semiconductor surfaces, and chemisorption-induced changes in optical response of the nickel (111) surface

    Energy Technology Data Exchange (ETDEWEB)

    Whitmore, P.M.

    1982-10-01

    The evolution of molecular excited states near solid surfaces is investigated. The mechanisms through which energy is transferred to the surface are described within a classical image dipole picture of the interaction. More sophisticated models for the dielectric response of the solid surface add important new decay channels for the energy dissipation. The predictions and applicability of three of these refined theories are discussed.

  9. Electronic energy transfer from molecules to metal and semiconductor surfaces, and chemisorption-induced changes in optical response of the nickel (111) surface

    International Nuclear Information System (INIS)

    Whitmore, P.M.

    1982-10-01

    The evolution of molecular excited states near solid surfaces is investigated. The mechanisms through which energy is transferred to the surface are described within a classical image dipole picture of the interaction. More sophisticated models for the dielectric response of the solid surface add important new decay channels for the energy dissipation. The predictions and applicability of three of these refined theories are discussed

  10. Normal patterns of spontaneous activity are required for correct motor axon guidance and the expression of specific guidance molecules.

    Science.gov (United States)

    Hanson, M Gartz; Landmesser, Lynn T

    2004-09-02

    Rhythmic spontaneous electrical activity occurs in many parts of the developing nervous system, where it plays essential roles in the refinement of neural connections. By blocking or slowing this bursting activity, via in ovo drug applications at precise developmental periods, we show that such activity is also required at much earlier stages for spinal motoneurons to accurately execute their first major dorsal-ventral pathfinding decision. Blockade or slowing of rhythmic bursting activity also prevents the normal expression patterns of EphA4 and polysialic acid on NCAM, which may contribute to the pathfinding errors observed. More prolonged (E2-5) blockade resulted in a downregulation of LIM homeodomain transcription factors, but since this occurred only after the pathfinding errors and alterations in guidance molecules, it cannot have contributed to them.

  11. Effect of surface wettability caused by radiation induced surface activation on leidenfrost condition

    Energy Technology Data Exchange (ETDEWEB)

    Takamasa, T.; Hazuku, T.; Tamura, N.; Okamoto, K. [Tokyo Univ., Tokyo (Japan); Mishima, K. [Kyoto Univ., Kyoto (Japan); Furuya, M. [Central Research Institute of Electric Power Industry, Tokyo (Japan)

    2003-07-01

    Improving the limit of boiling heat transfer or critical heat flux requires that the cooling liquid can contact the heating surface, or a high-wettability, highly hydrophilic heating surface, even if a vapor bubble layer is generated on the surface. From this basis, we investigated surface wettability and Leidenfrost condition using metal oxides irradiated by {gamma}-rays. In our previous study, contact angle, an indicator of macroscopic wettability, of a water droplet on metal oxide at room temperature was measured by image processing of the images obtained by a CCD video camera. The results showed that the surface wettability on metal oxide pieces of titanium, Zircaloy No. 4, SUS-304, and copper was improved significantly by the Radiation Induced Surface Activation (RISA) phenomenon. To delineate the effect of Radiation Induced Surface Activation (RISA) on heat transferring phenomena, the Leidenfrost condition and quenching of metal oxides irradiated by {gamma}-rays were investigated. In the Leidenfrost experiment, when the temperature of the heating surface reached the wetting limit temperature, water-solid contact vanished because a stable vapor film existed between the droplet and the metal surface; i.e., a Leidenfrost condition obtained. The wetting limit temperature increased with integrated irradiation dose. After irradiation, the wet length and the duration of contact increased, and the contact angle decreased. In the quenching test, high surface wettability, or a highly hydrophilic condition, of a simulated fuel rod made of SUS was achieved, and the quenching velocities were increased up to 20-30% after 300 kGy 60Co {gamma}-ray irradiation.

  12. In Situ Mapping of the Molecular Arrangement of Amphiphilic Dye Molecules at the TiO 2 Surface of Dye-Sensitized Solar Cells

    KAUST Repository

    Voïtchovsky, Kislon

    2015-05-27

    © 2015 American Chemical Society. Amphiphilic sensitizers are central to the function of dye-sensitized solar cells. It is known that the cell\\'s performance depends on the molecular arrangement and the density of the dye on the semiconductor surface, but a molecular-level picture of the cell-electrolyte interface is still lacking. Here, we present subnanometer in situ atomic force microscopy images of the Z907 dye at the surface of TiO2 in a relevant liquid. Our results reveal changes in the conformation and the lateral arrangement of the dye molecules, depending on their average packing density on the surface. Complementary quantitative measurements on the ensemble of the film are obtained by the quartz-crystal microbalance with dissipation technique. An atomistic picture of the dye coverage-dependent packing, the effectiveness of the hydrophobic alkyl chains as blocking layer, and the solvent accessibility is obtained from molecular dynamics simulations. (Figure Presented).

  13. Molecule Matters

    Indian Academy of Sciences (India)

    is a very stable and inert molecule due to the formation of a triple bond between the two atoms. Surpris- ingly isoelectronic molecules are quite reactive making dinitrogen very useful and unique. Dinitrogen (N. 2. ) is such an innocuous molecule that you might not think it worthy of special attention. We take this molecule for.

  14. Mechanism of Hydrophilicity by Radiation-Induced Surface Activation

    Science.gov (United States)

    Honjo, Yoshio; Furuya, Masahiro; Takamasa, Tomoji; Okamoto, Koji

    When a metal oxide is irradiated by gamma rays, the irradiated surface becomes hydrophilic. This surface phenomenon is called as radiation-induced surface activation (RISA) hydrophilicity. In order to investigate gamma ray-induced and photoinduced hydrophilicity, the contact angles of water droplets on a titanium dioxide surface were measured in terms of irradiation intensity and time for gamma rays of cobalt-60 and for ultraviolet rays. Reciprocals of the contact angles increased in proportion to the irradiation time before the contact angles reached its super-hydrophilic state. The irradiation time dependency is equal to each other qualitatively. In addition, an effect of ambient gas was investigated. In pure argon gas, the contact angle remains the same against the irradiation time. This clearly indicates that certain humidity is required in ambient gas to take place of RISA hydrophilicity. A single crystal titanium dioxide (100) surface was analyzed by X-ray photoelectron spectrometry (XPS). After irradiation with gamma rays, a peak was found in the O1s spectrum, which indicates the adsorption of dissociative water to a surface 5-fold coordinate titanium site, and the formation of a surface hydroxyl group. We conclude that the RISA hydrophilicity is caused by chemisorption of the hydroxyl group on the surface.

  15. Siloxides as supporting ligands in uranium(III)-mediated small-molecule activation

    Energy Technology Data Exchange (ETDEWEB)

    Mougel, Victor; Camp, Clement; Pecaut, Jacques; Mazzanti, Marinella [CEA-Grenoble (France). Lab. de Reconnaissance Ionique et Chimie de Coordination; Coperet, Christophe [ETH Zuerich (Switzerland). Lab. of Inorganic Chemistry; Maron, Laurent; Kefalidis, Christos E. [Toulouse Univ. (France). LPCNO, CNRS et INSA, UPS

    2012-12-03

    Siloxides support the reduction of small molecules with uranium complexes. The treatment of [U{N(SiMe_3)_2}{sub 3}] with HOSi(OtBu){sub 3} (3 equiv.) yielded a novel homoleptic uranium(III) siloxide complex 1, which acted as a two-electron reducing agent toward CS{sub 2} and CO{sub 2}. Uranium(III) siloxide complex 1 also reduced toluene to afford a diuranium inverted-sandwich complex. [German] Siloxide unterstuetzen die Reduktion kleiner Molekuele durch Uran-Komplexe. Die Behandlung von [U{N(SiMe_3)_2}{sub 3}] mit HOSi(OtBu){sub 3} (3 Aequiv.) liefert den neuartigen homoleptischen Uran(III)-Siloxid-Komplex 1, der als Zwei-Elektronen-Reduktionsmittel fuer CS{sub 2} und CO{sub 2} (siehe Schema) wirkt. Komplex 1 reduziert ausserdem Toluol und bildet einen invertierten Diuran-Sandwichkomplex.

  16. Activation of CO{sub 2} and related small molecules by neopentyl-derivatized uranium complexes

    Energy Technology Data Exchange (ETDEWEB)

    Schmidt, Anna-Corina

    2015-06-18

    This work reports the newly synthesized neopentyl derivatized tris(aryloxide) U{sup III} complex [(({sup nP,Me}ArO){sub 3}tacn)U{sup III}] (1) and its reactivity with small molecules like nitrous oxide (N{sub 2}O), carbon dioxide (CO{sub 2}), and sulfur dioxide (SO{sub 2}). Additionally, a deeper insight into covalency of U-R bonds with R = O, N and the participation of the f-orbitals to bonding are discussed. For this purpose, a large number of characterization methods were used, such as X-ray diffraction analysis, U{sup V}/vis/NIR, IR vibrational, Raman, X-ray absorption, EPR, and {sup 1}H, {sup 15}N, {sup 13}C and {sup 19}F NMR spectroscopy, cyclic voltammetry, SQUID magnetization measurements and DFT calculations. Moreover, all compounds were checked for purity by elemental analysis.

  17. Surface activation of dyed fabric for cellulase treatment.

    Science.gov (United States)

    Schimper, Christian B; Ibanescu, Constanta; Bechtold, Thomas

    2011-10-01

    Surface activation of fabric made from cellulose fibres, such as viscose, lyocell, modal fibres and cotton, can be achieved by printing of a concentrated NaOH-containing paste. From the concentration of reducing sugars formed in solution, an increase in intensity of the cellulase hydrolysis by a factor of six to eight was observed, which was mainly concentrated at the activated parts of the fabric surface. This method of local activation is of particular interest for modification of materials that have been dyed with special processes to attain an uneven distribution of dyestuff within the yarn cross-section, e.g., indigo ring-dyed denim yarn for jeans production. Fabrics made from regenerated cellulose fibres were used as model substrate to express the effects of surface activation on indigo-dyed material. Wash-down experiments on indigo-dyed denim demonstrated significant colour removal from the activated surface at low overall weight loss of 4-5%. The method is of relevance for a more eco-friendly processing of jeans in the garment industry. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Xalpha-DVM investigation of double water molecule interactions with active sites of alpha- and beta-subunits of hemoglobin

    Science.gov (United States)

    Yuryeva, Elmira I.

    In this work, the results of Xalpha-discrete variation method calculations of the electronic structure and interatomic parameters of chemical bonding between iron (II) and oxygen molecule with and without extra electrons and protons in active site (AS) of alpha- and beta-subunits of oxyhemoglobin are presented. The Skulachev model of O2 molecule existing in respiration medium in the 2H2O form was used. The introduction of extra electrons does not change considerably the interaction of the iron atom with the O2 oxygen molecule, but strengthens the repulsion in the Fe bond N bonds. In this case, the estimated effective charge of the iron atom is +1.8/1.5e for AS of alpha-/beta-subunits of oxyhemoglobin, and the magnetic moment of iron atoms becomes zero. The deoxygenation effect of the AS of the alpha- and beta-subunits of oxyhemoglobin is due to the ability of extra protons to break down covalent attraction between the iron atom and the nearest oxygen atom and also to weakening of the repulsive component of the covalent Fe bond N interactions.

  19. A fiber-modified adenoviral vector interacts with immunoevasion molecules of the B7 family at the surface of murine leukemia cells derived from dormant tumors

    Directory of Open Access Journals (Sweden)

    Rogée Sophie

    2011-08-01

    Full Text Available Abstract Tumor cells can escape the immune system by overexpressing molecules of the B7 family, e.g. B7-H1 (PD-L1 or CD86, which suppresses the anti-tumor T-cell responses through binding to the PD-1 receptor, and similarly for B7.1 (CD80, through binding to CTLA-4. Moreover, direct interactions between B7-H1 and B7.1 molecules are also likely to participate in the immunoevasion mechanism. In this study, we used a mouse model of tumor dormancy, DA1-3b leukemia cells. We previously showed that a minor population of DA1-3b cells persists in equilibrium with the immune system for long periods of time, and that the levels of surface expression of B7-H1 and B7.1 molecules correlates with the dormancy time. We found that leukemia cells DA1-3b/d365 cells, which derived from long-term dormant tumors and overexpressed B7-H1 and B7.1 molecules, were highly permissive to Ad5FB4, a human adenovirus serotype 5 (Ad5 vector pseudotyped with chimeric human-bovine fibers. Both B7-H1 and B7.1 were required for Ad5FB4-cell binding and entry, since (i siRNA silencing of one or the other B7 gene transcript resulted in a net decrease in the cell binding and Ad5FB4-mediated transduction of DA1-3b/d365; and (ii plasmid-directed expression of B7.1 and B7-H1 proteins conferred to Ad5FB4-refractory human cells a full permissiveness to this vector. Binding data and flow cytometry analysis suggested that B7.1 and B7-H1 molecules played different roles in Ad5FB4-mediated transduction of DA1-3b/d365, with B7.1 involved in cell attachment of Ad5FB4, and B7-H1 in Ad5FB4 internalization. BRET analysis showed that B7.1 and B7-H1 formed heterodimeric complexes at the cell surface, and that Ad5FB4 penton, the viral capsomere carrying the fiber projection, could negatively interfere with the formation of B7.1/B7-H1 heterodimers, or modify their conformation. As interactors of B7-H1/B7.1 molecules, Ad5FB4 particles and/or their penton capsomeres represent potential therapeutic agents

  20. Manipulating magnetism and conductance of an adatom-molecule junction on a metal surface: An ab initio study

    DEFF Research Database (Denmark)

    Tao, Kun; Stepanyuk, V.S.; Bruno, P.

    2008-01-01

    The state of the art ab initio calculations reveal the effect of a scanning tunneling microscopy tip on magnetic properties and conductance of a benzene-adatom sandwich on Cu(001). We concentrate on a benzene-Co system interacting with a Cr tip. Our studies give a clear evidence that magnetism...... and conductance in molecule-adatom junctions can be tailored by the STM tip. Varying the tip-substrate distance the magnetic moment of the Co adatom can be switched on/off. The interplay between spin-polarized electron transport through the junction and its magnetic properties is demonstrated. A spin...

  1. Active screen plasma nitriding enhances cell attachment to polymer surfaces

    International Nuclear Information System (INIS)

    Kaklamani, Georgia; Bowen, James; Mehrban, Nazia; Dong, Hanshan; Grover, Liam M.; Stamboulis, Artemis

    2013-01-01

    Active screen plasma nitriding (ASPN) is a well-established technique used for the surface modification of materials, the result of which is often a product with enhanced functional performance. Here we report the modification of the chemical and mechanical properties of ultra-high molecular weight poly(ethylene) (UHMWPE) using 80:20 (v/v) N 2 /H 2 ASPN, followed by growth of 3T3 fibroblasts on the treated and untreated polymer surfaces. ASPN-treated UHMWPE showed extensive fibroblast attachment within 3 h of seeding, whereas fibroblasts did not successfully attach to untreated UHMWPE. Fibroblast-coated surfaces were maintained for up to 28 days, monitoring their metabolic activity and morphology throughout. The chemical properties of the ASPN-treated UHMWPE surface were studied using X-ray photoelectron spectroscopy, revealing the presence of C-N, C=N, and C≡N chemical bonds. The elastic modulus, surface topography, and adhesion properties of the ASPN-treated UHMWPE surface were studied over 28 days during sample storage under ambient conditions and during immersion in two commonly used cell culture media.

  2. From Molecules to Surfaces: Radical-Based Mechanisms of Si-S and Si-Se Bond Formation on Silicon.

    Science.gov (United States)

    Buriak, Jillian M; Sikder, Md Delwar H

    2015-08-05

    The derivatization of silicon surfaces can have profound effects on the underlying electronic properties of the semiconductor. In this work, we investigate the radical surface chemistry of silicon with a range of organochalcogenide reagents (comprising S and Se) on a hydride-terminated silicon surface, to cleanly and efficiently produce surface Si-S and Si-Se bonds, at ambient temperature. Using a diazonium-based radical initiator, which induces formation of surface silicon radicals, a group of organochalcogenides were screened for reactivity at room temperature, including di-n-butyl disulfide, diphenyl disulfide, diphenyl diselenide, di-n-butyl sulfide, diphenyl selenide, diphenyl sulfide, 1-octadecanethiol, t-butyl disulfide, and t-butylthiol, which comprises the disulfide, diselenide, thiol, and thioether functionalities. The surface reactions were monitored by transmission mode Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy, and time-of-flight secondary ionization mass spectrometry. Calculation of Si-Hx consumption, a semiquantitative measure of yield of production of surface-bound Si-E bonds (E = S, Se), was carried out via FTIR spectroscopy. Control experiments, sans the BBD diazonium radical initiator, were all negative for any evident incorporation, as determined by FTIR spectroscopy. The functional groups that did react with surface silicon radicals included the dialkyl/diphenyl disulfides, diphenyl diselenide, and 1-octadecanethiol, but not t-butylthiol, diphenyl sulfide/selenide, and di-n-butyl sulfide. Through a comparison with the rich body of literature regarding molecular radicals, and in particular, silyl radicals, reaction mechanisms were proposed for each. Armed with an understanding of the reaction mechanisms, much of the known chemistry within the extensive body of radical-based reactivity has the potential to be harnessed on silicon and could be extended to a range of technologically relevant semiconductor

  3. Expression of costimulatory molecules in antigen-activated peritoneal macrophages treated with either ovalbumin or palmitoyl-ova conjugates

    OpenAIRE

    Oliveira, Flávia Márcia; Ruiz-de-Souza, Valéria; Campana-Pereira, Maria Aparecida; Gontijo, Cristiano Machado

    2013-01-01

    One of the mechanisms by which adjuvants are believed to promote T-cell activation and prevent induction of oral tolerance is by up-regulating the expression of co-stimulatory molecules on antigen presenting cells. Mice treated orally with palmitoyl-ovalbumin conjugates become immunized, while those treated with native ovalbumin (Ova) become tolerant. Cells from the peritoneal cavity of B6D2F1 mice were cultured in the presence of 0.01, or 0.1 mg/100ml of either Ova, or palmitoyl-Ova and test...

  4. Stabilization of the activated alphaMbeta2 integrin by a small molecule inhibits leukocyte migration and recruitment.

    Science.gov (United States)

    Björklund, Mikael; Aitio, Olli; Stefanidakis, Michael; Suojanen, Juho; Salo, Tuula; Sorsa, Timo; Koivunen, Erkki

    2006-03-07

    Integrins are potential targets for the development of antiinflammatory agents. Here we develop a novel high-throughput assay by allowing a chemical library to compete with phage display peptide binding and identify a novel small-molecule ligand to the leukocyte-specific alpha(M)beta(2) integrin. The identified thioxothiazolidine-containing compound, IMB-10, had an unexpected activity in that it stabilized binding of alpha(M)beta(2) to its endogenous ligands proMMP-9 and fibrinogen. Single amino acid substitutions in the activity-regulating C-terminal helix and the underlying region in the ligand-binding I domain of the integrin suppressed the effect of IMB-10. A computational model indicated that IMB-10 occupies a distinct cavity present only in the activated form of the integrin I domain. IMB-10 inhibited alpha(M)beta(2)-dependent migration in vitro and inflammation-induced neutrophil emigration in vivo. Stabilization of integrin-mediated adhesion by a small molecule is a novel means to inhibit cell migration and may have a utility in treatment of inflammatory diseases involving leukocyte recruitment.

  5. Effect of methylprednisolone on the oxidative burst activity, adhesion molecules and clinical outcome following open heart surgery

    DEFF Research Database (Denmark)

    Toft, P; Christiansen, K; Tønnesen, Else Kirstine

    1997-01-01

    Following cardiac surgery with cardiopulmonary bypass (CPB), activated granulocytes may be involved with ischaemia/ reperfusion injury. The purpose of this study was to investigate whether steroids could reduce the oxidative burst activity of granulocytes, the expression of adhesion molecules...... on granulocytes and improve clinical outcome. Sixteen patients undergoing open heart surgery participated in the study. Eight were randomized to receive methylprednisolone (30 mg/kg intravenously) at the start of anaesthesia while eight patients served as a control group. The oxidative burst was measured flow...... not improve the weaning from the ventilator or reduce the stay in the intensive-care unit. In conclusion, treatment with steroids prevented hyperthermia following open heart surgery with CPB and reduced capillary leak during ECC. Methylprednisolone, however, did not reduce the oxidative burst activity...

  6. Small-molecule inhibitors of SREBP activation – potential for new treatment of metabolic disorders

    OpenAIRE

    Watanabe, Mizuki; Uesugi, Motonari

    2013-01-01

    Sterol regulatory element-binding proteins (SREBPs) are transcriptional factors that control lipid and cholesterol metabolism. Activation of SREBPs in response to a decrease in cellular sterols results in acceleration of the synthesis of fatty acids, triglycerides, and cholesterol. Aberrant SREBP activity has been linked to metabolic disease states, such as obesity, fatty liver, insulin resistance, hyperlipidemia, and atherosclerosis. Thus, inhibition of SREBP activation is a potential therap...

  7. Using Force to Probe Single-Molecule Receptor-Cytoskeletal Anchoring Beneath the Surface of a Living Cell

    DEFF Research Database (Denmark)

    Evans, Evan; Kinoshita, Koji

    2007-01-01

    , K. (2005). Nano-to-micro scale dynamics of P-selectin detachment from leukocyte interfaces: I. Separation of PSGL-1 from the cell cytoskeleton. Biophys. J. 88, 2288-2298]. Retracting cells from receptor-surface attachments at many different speeds revealed that the kinetic rate for receptor......The ligation of cell surface receptors often communicates a signal that initiates a cytoplasmic chemical cascade to implement an important cell function. Less well understood is how physical stress applied to a cell surface adhesive bond propagates throughout the cytostructure to catalyze...... or trigger important steps in these chemical processes. Probing the nanoscale impact of pulling on cell surface bonds, we discovered that receptors frequently detach prematurely from the interior cytostructure prior to failure of the exterior adhesive bond [Evans, E., Heinrich, V., Leung, A., and Kinoshita...

  8. Spectroscopic Study of the Surface Oxidation of Mechanically Activated Sulphides

    Czech Academy of Sciences Publication Activity Database

    Godočíková, E.; Baláž, P.; Bastl, Zdeněk; Brabec, Libor

    2002-01-01

    Roč. 200, č. 1 (2002), s. 36-47 ISSN 0169-4332 Institutional research plan: CEZ:AV0Z4040901 Keywords : mechanical activation * surface oxidation * sulphide minerals Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.295, year: 2002

  9. Temperature effects on surface activity and application in oxidation ...

    Indian Academy of Sciences (India)

    Unknown

    Surface activity; cetyl trimethylammonium bromide; sodium dodecyl sulfate; temperature; oxidation. 1. Introduction. Cationic systems show strong synergism in their so- lutions and display physicochemical properties that differ distinctly from those of individual surfactants,1 due to their electrostatic interaction between oppo-.

  10. Improved efficiency of budesonide nebulization using surface-active agents

    NARCIS (Netherlands)

    Heijstra, M. P.; Schaefer, N. C.; Duiverman, E. J.; LeSouef, P. N.; Devadason, S. G.

    2006-01-01

    Our aim was to improve the efficiency of nebulised budesonide using surface-active agents. Cationic, anionic, and nonionic detergents were added to commercial budesonide suspension, and the particle size distribution during nebulization was measured using both cascade impaction and laser

  11. Design of an NF-kB Activation-Coupled Apoptotic Molecule for Prostate Cancer Therapy

    National Research Council Canada - National Science Library

    Yang, Wannian

    2008-01-01

    ...), that couples activation of NF-kB to activation of Caspase-3, thus to apoptosis. During the eighteen months, we constructed 32 plasmids for testing the function of NACAM and determined the expression of the plasmids in HEK293 cells...

  12. Activation of toll-like receptors and dendritic cells by a broad range of bacterial molecules

    NARCIS (Netherlands)

    Boele, L.C.L.; Bajramovic, J.J.; Vries, A.M.M.B.C. de; Voskamp-Visser, I.A.I.; Kaman, W.E.; Kleij, D. van der

    2009-01-01

    Activation of pattern recognition receptors such as Toll-like receptors (TLRs) by pathogens leads to activation and maturation of dendritic cells (DC), which orchestrate the development of the adaptive immune response. To create an overview of the effects of a broad range of pathogenic bacteria,

  13. High quality, small molecule-activity datasets for kinase research [version 3; referees: 2 approved

    Directory of Open Access Journals (Sweden)

    Rajan Sharma

    2016-10-01

    Full Text Available Kinases regulate cell growth, movement, and death. Deregulated kinase activity is a frequent cause of disease. The therapeutic potential of kinase inhibitors has led to large amounts of published structure activity relationship (SAR data. Bioactivity databases such as the Kinase Knowledgebase (KKB, WOMBAT, GOSTAR, and ChEMBL provide researchers with quantitative data characterizing the activity of compounds across many biological assays. The KKB, for example, contains over 1.8M kinase structure-activity data points reported in peer-reviewed journals and patents. In the spirit of fostering methods development and validation worldwide, we have extracted and have made available from the KKB 258K structure activity data points and 76K associated unique chemical structures across eight kinase targets. These data are freely available for download within this data note.

  14. High quality, small molecule-activity datasets for kinase research [version 1; referees: 2 approved

    Directory of Open Access Journals (Sweden)

    Rajan Sharma

    2016-06-01

    Full Text Available Kinases regulate cell growth, movement, and death. Deregulated kinase activity is a frequent cause of disease. The therapeutic potential of kinase inhibitors has led to large amounts of published structure activity relationship (SAR data. Bioactivity databases such as the Kinase Knowledgebase (KKB, WOMBAT, GOSTAR, and ChEMBL provide researchers with quantitative data characterizing the activity of compounds across many biological assays. The KKB, for example, contains over 1.8M kinase structure-activity data points reported in peer-reviewed journals and patents. In the spirit of fostering methods development and validation worldwide, we have extracted and have made available from the KKB 258K structure activity data points and 76K associated unique chemical structures across eight kinase targets. These data are freely available for download within this data note.

  15. High quality, small molecule-activity datasets for kinase research [version 2; referees: 2 approved

    Directory of Open Access Journals (Sweden)

    Rajan Sharma

    2016-07-01

    Full Text Available Kinases regulate cell growth, movement, and death. Deregulated kinase activity is a frequent cause of disease. The therapeutic potential of kinase inhibitors has led to large amounts of published structure activity relationship (SAR data. Bioactivity databases such as the Kinase Knowledgebase (KKB, WOMBAT, GOSTAR, and ChEMBL provide researchers with quantitative data characterizing the activity of compounds across many biological assays. The KKB, for example, contains over 1.8M kinase structure-activity data points reported in peer-reviewed journals and patents. In the spirit of fostering methods development and validation worldwide, we have extracted and have made available from the KKB 258K structure activity data points and 76K associated unique chemical structures across eight kinase targets. These data are freely available for download within this data note.

  16. Identification of novel orosensory active molecules in cured vanilla Beans (Vanilla planifolia).

    Science.gov (United States)

    Schwarz, Bernd; Hofmann, Thomas

    2009-05-13

    Sequential application of solvent extraction, gel permeation chromatography, and HPLC in combination with taste dilution analyses, followed by LC-MS and 1D/2D NMR experiments, led to the discovery of seven velvety mouth-coating molecules in cured beans of Vanilla planifolia . Among these, 5-(4-hydroxybenzyl)vanillin, 4-(4-hydroxybenzyl)-2-methoxyphenol, 4-hydroxy-3-(4-hydroxy-3-methoxybenzyl)-5-methoxybenzaldehyde, (1-O-vanilloyl)-(6-O-feruloyl)-beta-d-glucopyranoside, americanin A, and 4',6'-dihydroxy-3',5-dimethoxy-[1,1'-biphenyl]-3-carboxaldehyde were previously not reported in vanilla beans. Sensory studies revealed human recognition thresholds for the velvety mouth-coating sensation between 1.0 and 5.0 mumol/kg (water). Interestingly, the biphenyl derivatives were found to enhance the perception of creaminess and fatty body of sweetened skim milk, among which 4',6'-dihydroxy-3',5-dimethoxy-[1,1'-biphenyl]-3-carboxaldehyde showed the lowest threshold level of 5 mumol/kg. Quantitative analysis of these compounds in cured vanilla beans from different origins as well as in noncured beans revealed that, with the exception of americanin A, all of the other taste compounds are not present in the green vanilla beans and are formed during the bean curing process.

  17. Remarkable enhancement of O₂ activation on yttrium-stabilized zirconia surface in a dual catalyst bed.

    Science.gov (United States)

    Richard, Mélissandre; Can, Fabien; Duprez, Daniel; Gil, Sonia; Giroir-Fendler, Anne; Bion, Nicolas

    2014-10-13

    Yttrium-stabilized zirconia (YSZ) has been extensively studied as an electrolyte material for solid oxide fuel cells (SOFC) but its performance in heterogeneous catalysis is also the object of a growing number of publications. In both applications, oxygen activation on the YSZ surface remains the step that hinders utilization at moderate temperature. It was demonstrated by oxygen isotope exchange that a dual catalyst bed system consisting of two successive LaMnO3 and YSZ beds without intimate contact drastically enhances oxygen activation on the YSZ surface at 698 K. It can be concluded that LaMnO3 activates the triplet ground-state of molecular oxygen into a low-lying singlet state, thereby facilitating the activation of the O2 molecule on the YSZ oxygen vacancy sites. This phenomenon is shown to improve the catalytic activity of the LaMnO3-Pd/YSZ system for the partial oxidation of methane. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Activity of catalase adsorbed to carbon nanotubes: effects of carbon nanotube surface properties.

    Science.gov (United States)

    Zhang, Chengdong; Luo, Shuiming; Chen, Wei

    2013-09-15

    Nanomaterials have been studied widely as the supporting materials for enzyme immobilization. However, the interactions between enzymes and carbon nanotubes (CNT) with different morphologies and surface functionalities may vary, hence influencing activities of the immobilized enzyme. To date how the adsorption mechanisms affect the activities of immobilized enzyme is not well understood. In this study the adsorption of catalase (CAT) on pristine single-walled carbon nanotubes (SWNT), oxidized single-walled carbon nanotubes (O-SWNT), and multi-walled carbon nanotubes (MWNT) was investigated. The adsorbed enzyme activities decreased in the order of O-SWNT>SWNT>MWNT. Fourier transforms infrared spectroscopy (FTIR) and circular dichrois (CD) analyses reveal more significant loss of α-helix and β-sheet of MWNT-adsorbed than SWNT-adsorbed CAT. The difference in enzyme activities between MWNT-adsorbed and SWNT-adsorbed CAT indicates that the curvature of surface plays an important role in the activity of immobilized enzyme. Interestingly, an increase of β-sheet content was observed for CAT adsorbed to O-SWNT. This is likely because as opposed to SWNT and MWNT, O-SWNT binds CAT largely via hydrogen bonding and such interaction allows the CAT molecule to maintain the rigidity of enzyme structure and thus the biological function. Copyright © 2013 Elsevier B.V. All rights reserved.

  19. A bioassay-guided fractionation system to identify endogenous small molecules that activate plasma membrane H+-ATPase activity in Arabidopsis.

    Science.gov (United States)

    Han, Xiuli; Yang, Yongqing; Wu, Yujiao; Liu, Xiaohui; Lei, Xiaoguang; Guo, Yan

    2017-05-17

    Plasma membrane (PM) H+-ATPase is essential for plant growth and development. Various environmental stimuli regulate its activity, a process that involves many protein cofactors. However, whether endogenous small molecules play a role in this regulation remains unknown. Here, we describe a bio-guided isolation method to identify endogenous small molecules that regulate PM H+-ATPase activity. We obtained crude extracts from Arabidopsis seedlings with or without salt treatment and then purified them into fractions based on polarity and molecular mass by repeated column chromatography. By evaluating the effect of each fraction on PM H+-ATPase activity, we found that fractions containing the endogenous, free unsaturated fatty acids oleic acid (C18:1), linoleic acid (C18:2), and linolenic acid (C18:3) extracted from salt-treated seedlings stimulate PM H+-ATPase activity. These results were further confirmed by the addition of exogenous C18:1, C18:2, or C18:3 in the activity assay. The ssi2 mutant, with reduced levels of C18:1, C18:2, and C18:3, displayed reduced PM H+-ATPase activity. Furthermore, C18:1, C18:2, and C18:3 directly bound to the C-terminus of the PM H+-ATPase AHA2. Collectively, our results demonstrate that the binding of free unsaturated fatty acids to the C-terminus of PM H+-ATPase is required for its activation under salt stress. The bio-guided isolation model described in this study could enable the identification of new endogenous small molecules that modulate essential protein functions, as well as signal transduction, in plants. © The Author 2017. Published by Oxford University Press on behalf of the Society for Experimental Biology.

  20. Cardiac-Specific SOCS3 Deletion Prevents In Vivo Myocardial Ischemia Reperfusion Injury through Sustained Activation of Cardioprotective Signaling Molecules.

    Directory of Open Access Journals (Sweden)

    Takanobu Nagata

    Full Text Available Myocardial ischemia reperfusion injury (IRI adversely affects cardiac performance and the prognosis of patients with acute myocardial infarction. Although myocardial signal transducer and activator of transcription (STAT 3 is potently cardioprotective during IRI, the inhibitory mechanism responsible for its activation is largely unknown. The present study aimed to investigate the role of the myocardial suppressor of cytokine signaling (SOCS-3, an intrinsic negative feedback regulator of the Janus kinase (JAK-STAT signaling pathway, in the development of myocardial IRI. Myocardial IRI was induced in mice by ligating the left anterior descending coronary artery for 1 h, followed by different reperfusion times. One hour after reperfusion, the rapid expression of JAK-STAT-activating cytokines was observed. We precisely evaluated the phosphorylation of cardioprotective signaling molecules and the expression of SOCS3 during IRI and then induced myocardial IRI in wild-type and cardiac-specific SOCS3 knockout mice (SOCS3-CKO. The activation of STAT3, AKT, and ERK1/2 rapidly peaked and promptly decreased during IRI. This decrease correlated with the induction of SOCS3 expression up to 24 h after IRI in wild-type mice. The infarct size 24 h after reperfusion was significantly reduced in SOCS3-CKO compared with wild-type mice. In SOCS3-CKO mice, STAT3, AKT, and ERK1/2 phosphorylation was sustained, myocardial apoptosis was prevented, and the expression of anti-apoptotic Bcl-2 family member myeloid cell leukemia-1 (Mcl-1 was augmented. Cardiac-specific SOCS3 deletion led to the sustained activation of cardioprotective signaling molecules including and prevented myocardial apoptosis and injury during IRI. Our findings suggest that SOCS3 may represent a key factor that exacerbates the development of myocardial IRI.

  1. Surface enhanced Raman scattering activity of dual-functional Fe3O4/Au composites

    Science.gov (United States)

    Wang, Li-Ping; Huang, Yu-Bin; Lai, Ying-Huang

    2018-03-01

    There is a high demand for multifunctional materials that can integrate sample collection and sensing. In this study, magnetic Fe3O4 clusters were fabricated using a simple solvent-thermal method. The effect of the reductant (sodium citrate, SC) on the structure and morphology of Fe3O4 was examined by the variation in the reagent amount. The resulting Fe3O4 clusters were functionalized with 3-aminopropyltriethoxysilane (APTES) to anchor Au nanoparticles to its surface. The fabricated composites were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and a superconducting quantum interference device (SQUID) magnetometer. Dual-functional Fe3O4/Au clusters were obtained, effectively combining magnetic and plasmonic optical properties. The magnetic Fe3O4 cluster cores permitted the adsorption of the probe molecules, while sample concentration and collection were carried out under an external magnetic field. In addition, 4-nitrothiophenol (4-NTP) was chosen as the probe molecule to examine the analyte concentration ability and surface-enhanced Raman scattering (SERS) activity of the Fe3O4/Au composites. The results indicated that the Fe3O4/Au clusters exhibit a prominent SERS effect. The best 4-NTP detection limit obtained was 1 × 10-8 M, with a corresponding SERS analytical enhancement factor (AEF) exceeding 2 × 105.

  2. Isolation and Molecular Characterization of Biofouling Bacteria and Profiling of Quorum Sensing Signal Molecules from Membrane Bioreactor Activated Sludge

    Directory of Open Access Journals (Sweden)

    Harshad Lade

    2014-02-01

    Full Text Available The formation of biofilm in a membrane bioreactor depends on the production of various signaling molecules like N-acyl homoserine lactones (AHLs. In the present study, a total of 200 bacterial strains were isolated from membrane bioreactor activated sludge and screened for AHLs production using two biosensor systems, Chromobacterium violaceum CV026 and Agrobacterium tumefaciens A136. A correlation between AHLs production and biofilm formation has been made among screened AHLs producing strains. The 16S rRNA gene sequence analysis revealed the dominance of Aeromonas and Enterobacter sp. in AHLs production; however few a species of Serratia, Leclercia, Pseudomonas, Klebsiella, Raoultella and Citrobacter were also identified. The chromatographic characterization of sludge extract showed the presence of a broad range of quorum sensing signal molecules. Further identification of sludge AHLs by thin layer chromatography bioassay and high performance liquid chromatography confirms the presence of C4-HSL, C6-HSL, C8-HSL, 3-oxo-C8-HSL, C10-HSL, C12-HSL, 3-oxo-C12-HSL and C14-HSL. The occurrence of AHLs in sludge extract and dominance of Aeromonas and Enterobacter sp. in activated sludge suggests the key role of these bacterial strains in AHLs production and thereby membrane fouling.

  3. Isolation and molecular characterization of biofouling bacteria and profiling of quorum sensing signal molecules from membrane bioreactor activated sludge.

    Science.gov (United States)

    Lade, Harshad; Paul, Diby; Kweon, Ji Hyang

    2014-02-04

    The formation of biofilm in a membrane bioreactor depends on the production of various signaling molecules like N-acyl homoserine lactones (AHLs). In the present study, a total of 200 bacterial strains were isolated from membrane bioreactor activated sludge and screened for AHLs production using two biosensor systems, Chromobacterium violaceum CV026 and Agrobacterium tumefaciens A136. A correlation between AHLs production and biofilm formation has been made among screened AHLs producing strains. The 16S rRNA gene sequence analysis revealed the dominance of Aeromonas and Enterobacter sp. in AHLs production; however few a species of Serratia, Leclercia, Pseudomonas, Klebsiella, Raoultella and Citrobacter were also identified. The chromatographic characterization of sludge extract showed the presence of a broad range of quorum sensing signal molecules. Further identification of sludge AHLs by thin layer chromatography bioassay and high performance liquid chromatography confirms the presence of C4-HSL, C6-HSL, C8-HSL, 3-oxo-C8-HSL, C10-HSL, C12-HSL, 3-oxo-C12-HSL and C14-HSL. The occurrence of AHLs in sludge extract and dominance of Aeromonas and Enterobacter sp. in activated sludge suggests the key role of these bacterial strains in AHLs production and thereby membrane fouling.

  4. Activation of Apoptotic Signal in Endothelial Cells through Intracellular Signaling Molecules Blockade in Tumor-Induced Angiogenesis

    Directory of Open Access Journals (Sweden)

    Hossein Bazmara

    2015-01-01

    Full Text Available Tumor-induced angiogenesis is the bridge between avascular and vascular tumor growth phases. In tumor-induced angiogenesis, endothelial cells start to migrate and proliferate toward the tumor and build new capillaries toward the tumor. There are two stages for sprout extension during angiogenesis. The first stage is prior to anastomosis, when single sprouts extend. The second stage is after anastomosis when closed flow pathways or loops are formed and blood flows in the closed loops. Prior to anastomosis, biochemical and biomechanical signals from extracellular matrix regulate endothelial cell phenotype; however, after anastomosis, blood flow is the main regulator of endothelial cell phenotype. In this study, the critical signaling pathways of each stage are introduced. A Boolean network model is used to map environmental and flow induced signals to endothelial cell phenotype (proliferation, migration, apoptosis, and lumen formation. Using the Boolean network model, blockade of intracellular signaling molecules of endothelial cell is investigated prior to and after anastomosis and the cell fate is obtained in each case. Activation of apoptotic signal in endothelial cell can prevent the extension of new vessels and may inhibit angiogenesis. It is shown that blockade of a few signaling molecules in endothelial cell activates apoptotic signal that are proposed as antiangiogenic strategies.

  5. Surface active complexes formed between keratin polypeptides and ionic surfactants.

    Science.gov (United States)

    Pan, Fang; Lu, Zhiming; Tucker, Ian; Hosking, Sarah; Petkov, Jordan; Lu, Jian R

    2016-12-15

    Keratins are a group of important proteins in skin and hair and as biomaterials they can provide desirable properties such as strength, biocompatibility, and moisture regaining and retaining. The aim of this work is to develop water-soluble keratin polypeptides from sheep wool and then explore how their surface adsorption behaves with and without surfactants. Successful preparation of keratin samples was demonstrated by identification of the key components from gel electrophoresis and the reproducible production of gram scale samples with and without SDS (sodium dodecylsulphate) during wool fibre dissolution. SDS micelles could reduce the formation of disulphide bonds between keratins during extraction, reducing inter-molecular crosslinking and improving keratin polypeptide solubility. However, Zeta potential measurements of the two polypeptide batches demonstrated almost identical pH dependent surface charge distributions with isoelectric points around pH 3.5, showing complete removal of SDS during purification by dialysis. In spite of different solubility from the two batches of keratin samples prepared, very similar adsorption and aggregation behavior was revealed from surface tension measurements and dynamic light scattering. Mixing of keratin polypeptides with SDS and C 12 TAB (dodecyltrimethylammonium bromide) led to the formation of keratin-surfactant complexes that were substantially more effective at reducing surface tension than the polypeptides alone, showing great promise in the delivery of keratin polypeptides via the surface active complexes. Neutron reflection measurements revealed the coexistence of surfactant and keratin polypeptides at the interface, thus providing the structural support to the observed surface tension changes associated with the formation of the surface active complexes. Copyright © 2016. Published by Elsevier Inc.

  6. Microstructure and surface properties of lignocellulosic-based activated carbons

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez-Garcia, P., E-mail: pegonzal@quim.ucm.es [Departamento de Quimica Inorganica, Facultad de Ciencias Quimicas, Universidad Complutense, E-28040, Madrid (Spain); Centeno, T.A. [Instituto Nacional del Carbon-CSIC, Apartado 73, E-33080 Oviedo (Spain); Urones-Garrote, E. [Centro Nacional de Microscopia Electronica, Universidad Complutense, E-28040, Madrid (Spain); Avila-Brande, D.; Otero-Diaz, L.C. [Departamento de Quimica Inorganica, Facultad de Ciencias Quimicas, Universidad Complutense, E-28040, Madrid (Spain)

    2013-01-15

    Highlights: Black-Right-Pointing-Pointer Activated carbons were produced by KOH activation at 700 Degree-Sign C. Black-Right-Pointing-Pointer The observed nanostructure consists of highly disordered graphene-like layers with sp{sup 2} bond content Almost-Equal-To 95%. Black-Right-Pointing-Pointer Textural parameters show high surface area ( Almost-Equal-To 1000 m{sup 2}/g) and pore width of 1.3-1.8 nm. Black-Right-Pointing-Pointer Specific capacitance reaches values as high as 161 F/g. - Abstract: Low cost activated carbons have been produced via chemical activation, by using KOH at 700 Degree-Sign C, from the bamboo species Guadua Angustifolia and Bambusa Vulgaris Striata and the residues from shells of the fruits of Castanea Sativa and Juglans Regia as carbon precursors. The scanning electron microscopy micrographs show the conservation of the precursor shape in the case of the Guadua Angustifolia and Bambusa Vulgaris Striata activated carbons. Transmission electron microscopy analyses reveal that these materials consist of carbon platelet-like particles with variable length and thickness, formed by highly disordered graphene-like layers with sp{sup 2} content Almost-Equal-To 95% and average mass density of 1.65 g/cm{sup 3} (25% below standard graphite). Textural parameters indicate a high porosity development with surface areas ranging from 850 to 1100 m{sup 2}/g and average pore width centered in the supermicropores range (1.3-1.8 nm). The electrochemical performance of the activated carbons shows specific capacitance values at low current density (1 mA/cm{sup 2}) as high as 161 F/g in the Juglans Regia activated carbon, as a result of its textural parameters and the presence of pseudocapacitance derived from surface oxygenated acidic groups (mainly quinones and ethers) identified in this activated carbon.

  7. Nano-Hydroxyapatite Bone Substitute Functionalized with Bone Active Molecules for Enhanced Cranial Bone Regeneration.

    Science.gov (United States)

    Teotia, Arun Kumar; Raina, Deepak Bushan; Singh, Chandan; Sinha, Neeraj; Isaksson, Hanna; Tägil, Magnus; Lidgren, Lars; Kumar, Ashok

    2017-03-01

    The aim of this study was to synthesize and characterize a nano-hydroxyapatite (nHAP) and calcium sulfate bone substitute (NC) for cranioplasty. The NC was functionalized with low concentrations of bone morphogenetic protein-2 (BMP-2) and zoledronic acid (ZA) and characterized both in vitro and in vivo. In vitro studies included MTT, ALP assays, and fluorescent staining of Saos-2 (human osteoblasts) and MC3T3-E1 (murine preosteoblasts) cells cultured on NC. An in vivo study divided 20 male Wistar rats into four groups: control (defect only), NC, NC + ZA, and NC + ZA + rhBMP-2. The materials were implanted in an 8.5 mm critical size defect in the calvarium for 12 weeks. Micro-CT quantitative analysis was carried out in vivo at 8 weeks and ex vivo after 12 weeks. Mineralization was highest in the NC + ZA + rhBMP-2 group (13.0 ± 2.8 mm 3 ) compared to the NC + ZA group (9.0 ± 3.2 mm 3 ), NC group (6.4 ± 1.9 mm 3 ), and control group (3.4 ± 1.0 mm 3 ) after 12 weeks. Histological and spectroscopic analysis of the defect site provided a qualitative confirmation of neo-bone, which was in agreement with the micro-CT results. In conclusion, NC can be used as a carrier for bioactive molecules, and functionalization with rhBMP-2 and ZA in low doses enhances bone regeneration.

  8. Characterization of Heme Proteins Involved in Microbial Exoelectric Activity and Small Molecule-Sensing

    KAUST Repository

    Vogler, Malvina M.

    2018-01-01

    Heme proteins, also termed cytochromes, are a widespread class of metalloproteins containing an Fe-protoporphyrin IX cofactor. They perform numerous functions in nature such as oxygen-transport by hemoglobin, monooxygenation reactions catalyzed by Cytochrome P-450, and electron transfer reactions during photosynthesis. The differences between proteincofactor binding characteristics and the cofactor environment greatly influence the extensive range of functions. In this dissertation, proteins from the Mtr pathway of Shewanella oneidensis are characterized. These c-type cytochromes contain multiple heme cofactors per protein molecule that covalently attach to the protein amino acid sequence and are involved in electron transfer to extracellular metal oxides during anaerobic conditions. Successful recombinant expression of pathway components MtrC and MtrA is achieved in Escherichia coli. Heme-dependent gel staining and UV/Vis spectroscopy show characteristic c-type cytochrome characteristics. Mass spectrometry confirms that the correct extensive post-translational modifications were performed and the ten heme groups were incorporated per protein of MtrC and MtrA and the correct lipid-anchor was attached to extracellular MtrC. Raman spectroscopy measurements of MtrA provide intriguing structural information and highlight the strong influence of the heme cofactors within the protein structure. Next, an Arabidopsis thaliana protein is analyzed. It was previously identified via a motif search of the plant genome, based on conserved residues in the H4 NOX pocket. Here, the incorporation of a heme b cofactor is confirmed. UV/Vis spectroscopy under anaerobic conditions demonstrates reversible binding of nitric oxide to the heme iron and depicts the previously published characteristic absorption maxima for other H-NOX proteins.

  9. Characterization of Functionalized Self-Assembled Monolayers and Surface-Attached Interlocking Molecules Using Near-Edge X-ray Absorption Fine Structure Spectroscopy

    International Nuclear Information System (INIS)

    Willey, T; Willey, T

    2004-01-01

    Quantitative knowledge of the fundamental structure and substrate binding, as well as the direct measurement of conformational changes, are essential to the development of self-assembled monolayers (SAMs) and surface-attached interlocking molecules, catenanes and rotaxanes. These monolayers are vital to development of nano-mechanical, molecular electronic, and biological/chemical sensor applications. This dissertation investigates properties of functionalized SAMs in sulfur-gold based adsorbed molecular monolayers using quantitative spectroscopic techniques including near-edge x-ray absorption fine structure spectroscopy (NEXAFS) and x-ray photoelectron spectroscopy (XPS). The stability of the gold-thiolate interface is addressed. A simple model SAM consisting of dodecanethiol adsorbed on Au(111) degrades significantly in less than 24 hours under ambient laboratory air. S 2p and O 1s XPS show the gold-bound thiolates oxidize to sulfinates and sulfonates. A reduction of organic material on the surface and a decrease in order are observed as the layer degrades. The effect of the carboxyl vs. carboxylate functionalization on SAM structure is investigated. Carboxyl-terminated layers consisting of long alkyl-chain thiols vs. thioctic acid with short, sterically separated, alkyl groups are compared and contrasted. NEXAFS shows a conformational change, or chemical switchability, with carboxyl groups tilted over and carboxylate endgroups more upright. Surface-attached loops and simple surface-attached rotaxanes are quantitatively characterized, and preparation conditions that lead to desired films are outlined. A dithiol is often insufficient to form a molecular species bound at each end to the substrate, while a structurally related disulfide-containing polymer yields surface-attached loops. Similarly, spectroscopic techniques show the successful production of a simple, surface-attached rotaxane that requires a ''molecular riveting'' step to hold the mechanically attached

  10. Surface barrier silicon detectors with a large active area

    International Nuclear Information System (INIS)

    Kim, Y.; Husimi, K.; Ikeda, Y.; Kim, C.; Ohkawa, S.; Sakai, T.

    1985-01-01

    Surface barrier silicon detectors with a large active area have been produced by using high resistive n-type silicon crystals, diameters of which are 3 to 5 inches. High quality detectors with a low leakage current and a low noise were achieved by developing the improved surface treatment. Characteristics of detectors obtained are good in energy resolution compared with conventional large area Si(Li) detectors. It has also been confirmed that local dead region is not found from measuring results of photo-pulse injection

  11. The Adsorption Geometry and Electronic Structure of Organic Dye Molecule on TiO2(101 Surface from First Principles Calculations

    Directory of Open Access Journals (Sweden)

    Niu Mang

    2017-01-01

    Full Text Available Using density functional theory (DFT, we have investigated the structural and electronic properties of dye-sensitized solar cells (DSSCs comprised of I-doped anatase TiO2(101 surface sensitized with NKX-2554 dye. The calculation results indicate that the cyanoacrylic acid anchoring group in NKX-2554 has a strong binding to the TiO2(101 surface. The dissociative and bidentate bridging type was found to be the most favorable adsorption configuration. On the other hand, the incorporations of I dopant can reduce the band gap of TiO2 photoanode and improve the of NKX-2554 dye, which can improve the visible-light absorption of anatase TiO2 and can also facilitate the electron injection from the dye molecule to the TiO2 substrate. As a result, the I doping can significantly enhance the incident photon-to-current conversion efficiency (IPCE of DSSCs.

  12. Nanostructured surface topographies have an effect on bactericidal activity.

    Science.gov (United States)

    Wu, Songmei; Zuber, Flavia; Maniura-Weber, Katharina; Brugger, Juergen; Ren, Qun

    2018-02-28

    Due to the increased emergence of antimicrobial resistance, alternatives to minimize the usage of antibiotics become attractive solutions. Biophysical manipulation of material surface topography to prevent bacterial adhesion is one promising approach. To this end, it is essential to understand the relationship between surface topographical features and bactericidal properties in order to develop antibacterial surfaces. In this work a systematic study of topographical effects on bactericidal activity of nanostructured surfaces is presented. Nanostructured Ormostamp polymer surfaces are fabricated by nano-replication technology using nanoporous templates resulting in 80-nm diameter nanopillars. Six Ormostamp surfaces with nanopillar arrays of various nanopillar densities and heights are obtained by modifying the nanoporous template. The surface roughness ranges from 3.1 to 39.1 nm for the different pillar area parameters. A Gram-positive bacterium, Staphylococcus aureus, is used as the model bacterial strain. An average pillar density at ~ 40 pillars μm -2 with surface roughness of 39.1 nm possesses the highest bactericidal efficiency being close to 100% compared with 20% of the flat control samples. High density structures at ~ 70 pillars μm -2 and low density structures at bactericidal efficiency to almost the level of the control samples. The results obtained here suggests that the topographical effects including pillar density and pillar height inhomogeneity may have significant impacts on adhering pattern and stretching degree of bacterial cell membrane. A biophysical model is prepared to interpret the morphological changes of bacteria on these nanostructures.

  13. Molecule nanoweaver

    Science.gov (United States)

    Gerald, II; Rex, E [Brookfield, IL; Klingler, Robert J [Glenview, IL; Rathke, Jerome W [Homer Glen, IL; Diaz, Rocio [Chicago, IL; Vukovic, Lela [Westchester, IL

    2009-03-10

    A method, apparatus, and system for constructing uniform macroscopic films with tailored geometric assemblies of molecules on the nanometer scale. The method, apparatus, and system include providing starting molecules of selected character, applying one or more force fields to the molecules to cause them to order and condense with NMR spectra and images being used to monitor progress in creating the desired geometrical assembly and functionality of molecules that comprise the films.

  14. Energy expenditure and muscular activation patterns through active sitting on compliant surfaces

    Directory of Open Access Journals (Sweden)

    D. Clark Dickin

    2017-06-01

    Conclusion: Compliant surfaces resulted in higher levels of muscular activation in the lower extremities facilitating increased caloric expenditure. Given the increasing trends in sedentary careers and the increases in obesity, this is an important finding to validate the merits of active sitting facilitating increased caloric expenditure and muscle activation.

  15. Infrared absorption by molecular gases as a probe of nanoporous silica xerogel and molecule-surface collisions: Low-pressure results

    Science.gov (United States)

    Vander Auwera, J.; Ngo, N. H.; El Hamzaoui, H.; Capoen, B.; Bouazaoui, M.; Ausset, P.; Boulet, C.; Hartmann, J.-M.

    2013-10-01

    Transmission spectra of gases confined (but not adsorbed) within the pores of a 1.4-cm-thick silica xerogel sample have been recorded between 2.5 and 5 μm using a high-resolution Fourier transform spectrometer. This was done for pure CO, CO2, N2O, H2O, and CH4 at room temperature and pressures of a few hectopascals. Least-squares fits of measured absorption lines provide the optical-path lengths within the confined (LC) and free (LF) gas inside the absorption cell and the half width at half maximum ΓC of the lines of the confined gases. The values of LC and LF retrieved using numerous transitions of all studied species are very consistent. Furthermore, LC is in satisfactory agreement with values obtained from independent measurements, thus showing that reliable information on the open porosity volume can be retrieved from an optical experiment. The values of ΓC, here resulting from collisions of the molecules with the inner surfaces of the xerogel pores, are practically independent of the line for each gas and inversely proportional to the square root of the probed-molecule molar mass. This is a strong indication that, for the studied transitions, a single collision of a molecule with a pore surface is sufficient to change its rotational state. A previously proposed simple model, used for the prediction of the line shape, leads to satisfactory agreement with the observations. It also enables a determination of the average pore size, bringing information complementary to that obtained from nitrogen adsorption porosimetry.

  16. Vibrational analysis of pyramidal XY3-type molecules based on high-level ab initio potential energy surfaces: application to NH3

    Science.gov (United States)

    Lin, H.; Thiel, W.; Yurchenko, S. N.; Carvajal, M.; Jensen, P.

    Variational calculations of the vibrational energies of the non-rigid and semirigid XY3 molecules, as ammonia and phosphine respectively, have been carried out [1,2]. In the procedure used is emphasized the umbrella motion due to the corresponding coordinate, for pyramidal non-rigid XY3 molecules, is the responsible of the torsional tunneling between different minima of the Potential Energy Surfaces. For the NH3 analytical potential energy surfaces were constructed from CCSD(T)/aug-cc-pVTZ ab initio data augmented by the results obtained by extrapolating CCSD(T)/aug-cc-pVXZ (X=T,Q,5) results to the complete basis set limit and adding corrections for core-valence correlation and relativistic effects. The vibrational energies were calculated by employing a kinetic energy operator expressed in terms of linearized internal coordinates. The exact internal coordinates were expressed as sixth-order Taylor expansions in the linearized coordinates. In the present work we show the latter improvement in the calculated vibrational energies with respect to the latter report [1]. This work is supported by the European Commission through contract no. HPRN-CT-2000-00022 ``Spectroscopy of Highly Excited Rovibrational States''.

  17. Density functional theory modeling of the adsorption of small analyte and indicator dye 9-(diphenylamino)acridine molecules on the surface of amorphous silica nanoparticles.

    Science.gov (United States)

    Chashchikhin, Vladimir; Rykova, Elena; Bagaturyants, Alexander

    2011-01-28

    The adsorption of small analyte molecules (H(2)O, NH(3), C(2)H(5)OH, and (CH(3))(2)CO) and an indicator dye, 9-(diphenylamino)acridine (DPAA), on the surface of amorphous silica particles is studied using electronic structure calculations at the DFT-D level of theory taking into account explicit corrections for van der Waals forces. Cluster models of three different types are used; two of them have been constructed using classical MD methods. The effect of particle size, local environment, and the choice of the exchange-correlation functional and basis set on the adsorption energies is studied, and adsorption energies are extrapolated to nanosized clusters. It is shown that the dye is more strongly bound to amorphous silica particles than the studied analyte molecules and that the energy of DPAA adsorption increases with the particle size, being at least twice as high as the energy of analyte adsorption for nanosized clusters. Electrostatic interactions play an important role in the adsorption of acridine dyes on the surface of silica nanoparticles.

  18. Modeling Nonreactive Molecule-Surface Systems on Experimentally Relevant Time and Length Scales: Dynamics and Conductance of Polyfluorene on Au(111).

    Science.gov (United States)

    Li, Zhi; Tkatchenko, Alexandre; Franco, Ignacio

    2018-03-01

    We propose a computationally efficient strategy to accurately model nonreactive molecule-surface interactions that adapts density functional theory calculations with the Tkatchenko-Scheffler scheme for van der Waals interactions into a simple classical force field. The resulting force field requires just two adjustable parameters per atom type that are needed to capture short-range and polarization interactions. The developed strategy allows for classical molecular dynamics simulation of molecules on surfaces with the accuracy of high-level electronic structure methods but for system sizes (10 3 to 10 7 atoms) and timescales (picoseconds to microseconds) that go well beyond what can be achieved with first-principles methods. Parameters for H, sp 2 C, and O on Au(111) are developed and employed to atomistically model experiments that measure the conductance of a single polyfluorene on Au(111) as a continuous function of its length. The simulations qualitatively capture both the gross and fine features of the observed conductance decay during initial junction elongation and lead to a revised atomistic understanding of the experiment.

  19. Telomerase activated thymidine analogue pro-drug is a new molecule targeting hepatocellular carcinoma

    Science.gov (United States)

    Tarocchi, Mirko; Polvani, Simone; Peired, Anna Julie; Marroncini, Giada; Calamante, Massimo; Ceni, Elisabetta; Rhodes, Daniela; Mello, Tommaso; Pieraccini, Giuseppe; Quattrone, Alessandro; Luchinat, Claudio; Galli, Andrea

    2014-01-01

    Background & Aims Hepatocellular carcinoma (HCC) is one of the most common malignancies worldwide. Although hepatectomy and transplantation have significantly improved survival, there is no effective chemotherapeutic treatment for HCC and its prognosis remains poor. Sustained activation of telomerase is essential for the growth and progression of HCC, suggesting that telomerase is a rational target for HCC therapy. Therefore, we developed a thymidine analogue pro-drug, acycloguanosyl-5′-thymidyltriphosphate (ACV-TP-T), which is specifically activated by telomerase in HCC cells and investigated its anti-tumour efficacy. Methods First, we verified in vitro whether ACV-TP-T was a telomerase substrate. Second, we evaluated proliferation and apoptosis in murine (Hepa1-6) and human (Hep3B, HuH7, HepG2) hepatic cancer cells treated with ACV-TP-T. Next, we tested the in vivo treatment efficacy in HBV transgenic mice that spontaneously develop hepatic tumours, and in a syngeneic orthotopic murine model where HCC cells were implanted directly in the liver. Results In vitro characterization provided direct evidence that the pro-drug was actively metabolized in liver cancer cells by telomerase to release the active form of acyclovir. Alterations in cell cycle and apoptosis were observed following in vitro treatment with ACV-TP-T. In the transgenic and orthotopic mouse models, treatment with ACV-TP-T reduced tumour growth, increased apoptosis, and reduced the proliferation of tumour cells. Conclusions ACV-TP-T is activated by telomerase in HCC cells and releases active acyclovir that reduces proliferation and induces apoptosis in human and murine liver cancer cells. This pro-drug holds a great promise for the treatment of HCC. PMID:24862448

  20. Direct instrumental identification of catalytically active surface sites

    Science.gov (United States)

    Pfisterer, Jonas H. K.; Liang, Yunchang; Schneider, Oliver; Bandarenka, Aliaksandr S.

    2017-09-01

    The activity of heterogeneous catalysts—which are involved in some 80 per cent of processes in the chemical and energy industries—is determined by the electronic structure of specific surface sites that offer optimal binding of reaction intermediates. Directly identifying and monitoring these sites during a reaction should therefore provide insight that might aid the targeted development of heterogeneous catalysts and electrocatalysts (those that participate in electrochemical reactions) for practical applications. The invention of the scanning tunnelling microscope (STM) and the electrochemical STM promised to deliver such imaging capabilities, and both have indeed contributed greatly to our atomistic understanding of heterogeneous catalysis. But although the STM has been used to probe and initiate surface reactions, and has even enabled local measurements of reactivity in some systems, it is not generally thought to be suited to the direct identification of catalytically active surface sites under reaction conditions. Here we demonstrate, however, that common STMs can readily map the catalytic activity of surfaces with high spatial resolution: we show that by monitoring relative changes in the tunnelling current noise, active sites can be distinguished in an almost quantitative fashion according to their ability to catalyse the hydrogen-evolution reaction or the oxygen-reduction reaction. These data allow us to evaluate directly the importance and relative contribution to overall catalyst activity of different defects and sites at the boundaries between two materials. With its ability to deliver such information and its ready applicability to different systems, we anticipate that our method will aid the rational design of heterogeneous catalysts.

  1. Activity of processes on the visible surface of planets of Solar system

    Science.gov (United States)

    Vidmachenko, A. P.

    2016-05-01

    According to modern concepts bodies of the solar system formed from a single cloud of gas and dust. Calculations show that in the protoplanetary nebula where the temperature is lowered to 1600 K - appeared the first type of metal (aluminum and titanium) and metal oxides in the form of dust particles. With further decreasing temperature of the nebula to 1400 K - appeared also dust of iron and iron-nikel alloy; at 1300 K - appear solid silicates; magnesium minerals formed at T 1200 K. These components are material for the formation of basaltic rocks. At temperatures T 300 K begins to form water molecules. At 100-200 K in a remote part of the nebula - ammonia, methane and their ice are formed. In the outer part of Solar system this ices are now preserved in comet nuclei and in the icy satellites of giant planets. During T 400 million years after the formation of the Sun, at first - from dust component of the protoplanetary cloud was formed many intermediate bodies with the size of hundreds kilometers. Their gravitational interaction was reinforced in process of their grow. The bodies, which were growing fastest, they became the embryos of the future planets. All bodies of the solar system in different degrees show manifestations of different types of activity processes on the surface or at the level of the visible clouds. This activity depends on the distance of a particular body from the Sun, surface chemical composition, physical conditions at the surface and so on. The farther away from the Sun is the object, the temperature of its visible surface is lower, and by that more interesting is the set of processes, of chemical and physical transformations that there is possible to register. The surface of each planets of Solar system is very active in a variety of set temperature and chemical composition

  2. Design parameters for measurements of local catalytic activity on surfaces

    DEFF Research Database (Denmark)

    Johansson, Martin; Johannessen, Tue; Jørgensen, Jan Hoffmann

    2006-01-01

    Computational fluid dynamics in combination with experiments is used to characterize a gas sampling device for measurements of the local catalytic activity on surfaces. The device basically consists of a quartz capillary mounted concentrically inside an aluminum tube. Reactant gas is blown toward...... the catalytic surface through the annulus between the tubes, and the gas is sampled close to the surface by the capillary. The influence of various design parameters on the lateral resolution and sensitivity of the measurements is investigated. It is found that the cuter diameter of the annulus sets the upper......, the limits of the range in reaction rate, which can be Studied are estimated. (c) 2005 Elsevier B.V. All rights reserved....

  3. Single-molecule analysis of ligand efficacy in beta(2)AR-G-protein activation

    DEFF Research Database (Denmark)

    Gregorio, G. Glenn; Masureel, Matthieu; Hilger, Daniel

    2017-01-01

    G-protein-coupled receptor (GPCR)-mediated signal transduction is central to human physiology and disease intervention, yet the molecular mechanisms responsible for ligand-dependent signalling responses remain poorly understood. In class A GPCRs, receptor activation and G-protein coupling entail ...

  4. Study of surface activity of piroxicam at the interface of palm oil esters and various aqueous phases.